DESCRIPTION

ELECTROPHOTOGRAPHIC PHOTOCONDUCTOR, PRODUCTION METHOD THEREOF, IMAGE FORMING METHOD AND IMAGE FORMINGAPPARATUS USING PHOTOCONDUCTOR, AND PROCESS CARTRIDGE

Technical Field

The present invention relates to a long-lived, high-end

electrophotographic photoconductor (hereinafter may he referred

to as "photoconductor," "latent electrostatic image bearing

member" or "image bearing member") that can provide high-quality

image formation for prolonged periods, a method for producing the

electrophotographic photoconductor, an image forming method, an

image forming apparatus, and a process cartridge.

Background Art

Recently, organic photoconductors (OPC) have been

replacing inorganic photoconductor for their excellent performance

and various advantages, and are often applied to copiers, facsimile

machines, laser printers and complex machines thereof.

Examples of the reasons for this include (l) optical property such

as a wide range of the wavelength of light absorption and a large

amount of light absorption, (2) electric property of high sensitive

and stable charging property, (3) a wide range of material selection,

(4) easiness to produce, (5) low cost, and (6) non-toxicity.

As reducing the diameter of a photoconductor is progressed

by downsizing of image forming apparatuses recently and

high-speed movements and maintenance -free of apparatuses are

followed, highly durable photoconductors are being desired.

Viewed from this point, as a surface layer of the organic

photoconductor contains mainly low molecular charge transport

materials and inactive polymers, the organic photoconductor is

generally soft. Because of this chemical property, the organic

photoconductor has a disadvantage of frequent wearing caused by

mechanical overload through developing systems or cleaning

systems, when the organic photoconductor is repeatedly used in the

electrophotography process. Furthermore, because of increasing

demand of high image quality, rubber hardness and contact

pressure of cleaning blades are increased for the purpose of

improving cleaning with the trend of reducing the diameter of

toner particles, and such a requirement is a cause for accelerating

the wear of the photoconductor. Thus wear of the photoconductor

impairs sensitivity and electric property such as lowering of

charging, and causes lowering of image densities and abnormal

images of dirty backgrounds. Scratches due to localized wears

cause striped-dirt images due to defective cleaning. The

exhaustion of the life of the photoconductor is ratio-determined by

wears and scratches and thereby the photoconductor are led to the

replacement in the present condition.

Thus, for enhancing the durability of the organic

photoconductor (OPC), it is indispensable to lower wear degree and

it is in need of organic photoconductors that not only have a fine

surface for superior cleaning and adding transferring but also have

no long-term dependencies of places over electrophotographic

property and maintain stable high performance. For this reason,

this is the most urgent problem to be solved in the art.

Examples of the technology for improving wear resistance

property of the photosensitive layer include (l) a method for using

curable binder in a surface layer (see Patent Literature l), (2) a

method for using a high- molecular weight charge transport

material in a surface layer (see Patent Literature 2) and (3) a

method for using inorganic fillers dispersed in a surface layer (see

Patent Literature 3). Among these methods, the surface layer .

described in the method (l) has a tendency of lowering the image

density as residual potential is elevated by poor compatibility of

the curable binder with charge transport materials and the

presence of impurities such as a polymerization initiator and

unreacted residues. Although both the surface layer described in

the method (2) that contains a charge transportable polymer

material and the surface layer described in the method (3) that

contains dispersed inorganic fillers can improve wear resistance

property to some extents, the current situation is that fully

satisfactory durability required for organic photoconductors has

not yet been obtained. Additionally, the surface layer described in

the method (3) has a tendency of flowering image densities as

residual potential is elevated by charge traps that exist on the

inorganic filler surface. For this reason, any of these methods (l),

(2), and (3) has not yet succeeded in fully achieving overall

durability, including electric durability and mechanical durability

that are required for organic photoconductors.

For improving wear resistance property and scratch

resistant property of the surface layer described in the method (l),

a photoconductor containing multi-functional curable acrylate

monomers is proposed (see Patent Literature 4). Although this

Patent Literature discloses a photoconductor in which its

protective layer (or surface layer) disposed on the photosensitive

layer contains the multi-functional curable acrylate monomer, it

merely describes the fact that the protective layer may contain a

charge transport material and fails to provide a specific description.

Furthermore, when a low molecular weight charge transport

material is simply contained in the protective layer, its

compatibility with the cured material of the foregoing monomer

becomes a problem. As a result, this may cause deposition of the

low -molecular weight charge transport material and cracking in

the surface layer, and finally lowering its mechanical strength.

This Patent Literature also discloses that a polycarbonate resin is

contained in the surface layer for increased compatibility,' however,

this causes a reduction in the content of the curable acrylic

monomer and thus a sufficient wear resistance has not yet been

obtained with this method. With regards to a photoconductor

with no charge transport materials in the surface layer, the Patent

Literature discloses that the surface layer is made thin for

decreased exposed area potential, this photoconductor, however,

has a short life because of the thin surface layer. Besides, the

environmental stability of the charging potential and the exposed

area potential is poor, and the values of the charging potential and

the exposed area potential significantly fluctuate substantially

depending on the environmental temperature and humidity,

thereby failing to maintain sufficient values.

As an alternative wear resistance technology for the

photosensitive layer, a method for using coating solution

containing monomers having a carbon-carbon double bond, charge

transport materials having a carbon-carbon double bond, and

binder resins to form a charge transport layer is proposed (see

Patent Literature 5). The proposed binder resin is classified into

two types: one reactive to the charge transport materials having a

carbon-carbon double bond and one not reactive to the charge

transport materials having no carbon-carbon double bond. The

photoconductor draws attention because of the simultaneous

achievement of wear resistance property and superior electric

property; however, when a non-reactive binder resin is used, the

compatibility of the binder resin with the cured material produced

by reaction of the monomer with the charge transport material

becomes poor, surface unevenness occurs due to layer separation at

the time of cross -linking, thereby causing the tendency of defective

cleaning. In this case, specifically described one that not only

prevents the binder resin from monomer curing and but also is

used for producing a photoconductor is a bifunctional monomer.'

however, this bifunctional monomer has a small number of

functional groups, thus resulting in failure to obtain a sufficient

cross-linkage density and thereby wear resistance property is not

yet satisfactory. Moreover, even in the case where a reactive

binder is used, due to a small number of functional groups

contained in the monomer and the binder resin, the simultaneous

achievement of the bond amount of the charge transport materials

and cross-linkage density becomes difficult, and thereby electric

property and wear resistance property of the photoconductor are

not satisfactory.

Besides, the photosensitive layer containing a compound of a

cured hole transportable compound having two or more chain

polymerizable functional groups in the same molecule is proposed

(see Patent Literature 6). However, the photosensitive layer of

the proposition generates strain within a curable because a bulky

hole transportable compound has two or more chain polymerizable

functional groups, enhances an internal stress, tends to generate

surface layer roughness, and cracking over time, thereby failing to

achieve sufficient durability.

Besides, the electrophotographic photoconductor having

cured cross-linked layer of a radically polymerizable compound

having three or more functionalities with no charge transport

structure and a radically polymerizable compound having single

functionality with charge transport structure is proposed (see

Patent Literatures 7 to 20 for example). In these propositions,

using a monofunctional radically polymerizable compound with

charge transport structure controls mechanical and electrical

durability and generation of cracking in the photosensitive layer.

However, in case of forming this cross-linked layer, an acrylic

monomer having a multiple number of acrylic functional groups is

cured to achieve high wear resistance. In this case, the acrylic

cured material significantly shrinks in volume; thereby

adhesiveness with photosensitive layer, that is, a lower layer may

become insufficient. Besides, when an image forming apparatus

that poses a high mechanical hazard to the electrophotographic

photoconductor is used, there is an issue of yielding peeling of the

cross-linked layer and the electrophotographic photoconductor

cannot maintain sufficient wear resistance for prolonged periods.

There is no sufficient description about the photoconductor

temperature during curing for the formation of the cross-linked

layer, but there is only disclosed information of controlling the

photoconductor temperature at the time of exposure so as not to

exceed 5O ⁰ C; however, sufficient curing at around 50 ⁰ C of the

photoconductor temperature may not be expected and there is no

description of controlling photoconductor temperature controlling

method, thus there is no way but to shorten the exposure for

preventing the photoconductor temperature from exceeding 50 ⁰ C.

However, if the exposure time is shortened, promotion of sufficient

polymerization reaction may not be expected, thereby high wear

resistance for prolonged periods cannot be maintained.

Furthermore, in case of sufficient polymerization reaction, there is

no discussion about evenness of the photoconductor temperature.

Homogeneous polymerization of the cross-linked layer is undone

with subdued difference between maximum value and minimum

value of the post-exposure electrical potential, and thereby stable

photoconductor property for prolonged periods cannot be achieved.

Besides, there are proposals in which a prescribed

photoconductor temperature at the time of exposure is set by

forming a cross-linked surface layer by curing of a

photopolymerizable monomer (see Patent Literatures 21 and 22).

These propositions have no detailed explanation about the method

for controlling temperature, but only description of temperature

being controlled by air cooling in Examples! however, if air is used

as coolant media, cooling efficiency becomes very low because of its

low thermal conductivity, amount of heat which is generated by

curing with powerful irradiation light cannot be reduced, longtime

exposure becomes impossible, and thereby sufficient

polymerization reaction is not completed. Besides, in case of

method for controlling temperature, fluctuation of flow rate and

cooling efficiency by method becomes bigger and thereby cured

level of a cross-linked surface layer fluctuates. That is, the

dependency of places of wear resistance and electric property is

large, the difference between maximum value and minimum value

of the post-exposure electrical potential with respect to electric

property cannot be stemmed, and thereby stable property for

prolonged periods cannot be maintained.

Consequently, any of electrophotographic photoconductors

having a cross-linked layer which is chemically bonded with charge

transport structure in these conventional technologies has not yet

provided sufficient total property in the present state of affairs.

[Patent Literature 1] Japanese Patent Application Laid-Open

(JP-A) No. 56-48637

[Patent Literature 2] JP-A No. 64-1728

[Patent Literature 3] JP-A No. 04-281461

[Patent Literature 4] Japanese Patent (JP-B) No. 3262488

[Patent Literature 5] JP-B No. 3194392

[Patent Literature 6] JP-A No. 2000-66425

[Patent Literature 7] JP-A No. 2004-302450

[Patent Literature 8] JP-A No. 2004-302451

[Patent Literature 9] JP-A No. 2004-302452

[Patent Literature 10] JP-A No. 2005-099688

[Patent Literature 11] JP-A No. 2005-107401

[Patent Literature 12] JP-A No. 2005-107490

[Patent Literature 13] JP-A No. 2005-115322

[Patent Literature 14] JP-A No. 2005-140825

[Patent Literature 15] JP-A No. 2005-156784

[Patent Literature 16] JP-A No. 2005-157026

[Patent Literature 17] JP-A No. 2005-157297

[Patent Literature 18] JP-A No. 2005-189821

[Patent Literature 19] JP-A No. 2005-189828

[Patent Literature 20] JP-A No. 2005-189835

[Patent Literature 21] JP-A No. 2001-125297

[Patent Literature 22] JP-A No. 2004-240305

Disclosure of Invention

An object of the present invention is to provide a long-lived,

high-end electrophotographic photoconductor that maintains high

wear resistance for prolonged periods, has almost no electric

property fluctuation, has little dependencies of places of wear

resistance and electric property, has excellent durability and stable

electric property, can provide high-quality image forming for

prolonged periods, a method for producing an electrophotographic

photoconductor, an image forming method, an image forming

apparatus, and a process cartridge.

To resolve the problems described above, the present

inventors studied carefully and reached a conclusion that for an

electrophotographic photoconductor having a cross-linked layer

with at least a cured material obtained by irradiation of a radically

polymerizable compound with light, when writing is conducted

under the condition that image static power is 0.53mW and

exposure energy is 4.0erg/cm ² and the difference between the

maximum value of the post-exposure electrical potential and the

minimum value of the post-exposure electrical potential came

within 30V, the problems could be resolved.

The present invention is based on the knowledge by the

present inventors, the means for resolving the issues are as

follows.

<1> An electrophotographic photoconductor, including ^: a

support; and a cross-linked layer formed over the support, wherein

the cross-linked layer includes a cured material of a cross-linked

layer composition containing at least a radically polymerizable

compound, and wherein when the photoconductor is exposed at a

field static power of 0.53mw and exposure energy of 4.0 erg/cm ² ,

the difference between the maximum and minimum values of

post-exposure electrical potential is within 30V.

<2> The electrophotographic photoconductor according to <1>,

wherein the maximum value (Vmax) of the post-exposure electrical

potential is -60V or less.

<3> The electrophotographic photoconductor according to one of

<1> and <2>, wherein the radically polymerizable compound

includes both a radically polymerizable compound with charge

transport structure and the radically polymerizable compound

with no charge transport structure.

<4> The electrophotographic photoconductor according to <3>,

wherein the number of radically polymerizable functional groups

in a radically polymerizable compound with charge transport

structure is 1.

<5> The electrophotographic photoconductor according to one of

<3> and <4>, wherein the number of radically polymerizable

functional groups in the radically polymerizable compound with no

charge transport structure is 3 or more.

<6> The electrophotographic photoconductor according to any one of <1> to <5>, wherein the radically polymerizable functional

group in radically polymerizable compound is any one of

acryloyloxy group and methacryloyloxy group.

<7> The electrophotographic photoconductor according to any

one of <1> to <6>, wherein the cross-linked layer is any one of a

cross-linked surface layer, a cross-linked photosensitive layer, and

a cross-linked charge transport layer.

<8> The electrophotographic photoconductor according to <7>,

wherein a charge generating layer, a charge transport layer, and a

cross-linked surface layer are sequentially disposed over the

support.

<9> A method for producing an electrophotographic

photoconductor including: forming a cross-linked layer by curing at

least a radically polymerizable compound by irradiation with light,

wherein the difference between the maximum and minimum values

of the surface temperature over the entire surface of the

electrophotographic photoconductor, measured just before

completion of curing for the formation of the cross-linked layer, is

within 30°C, and wherein the electrophotographic photoconductor

is an electrophotographic photoconductor according to any one of

<1> to <8>.

<10> The method for producing an electrophotographic

photoconductor according to <9>, wherein the surface temperature

of the electrophotographic photoconductor during curing for the

formation of the cross-linked layer is 20 ⁰ C to 170°C.

<11> The method for producing an electrophotographic

photoconductor according to any one of <9> and <10>, wherein the

electrophotographic photoconductor is a hollow

electrophotographic photoconductor, and a heating medium exists

in the hollow space of the electrophotographic photoconductor

during curing for the formation of the cross-linked layer.

<12> The method for producing an electrophotographic

photoconductor according to <11>, wherein the heating medium is

water.

<13> The method for producing an electrophotographic

photoconductor according to one of <11> and <12>, wherein an

elastic member is closely attached to the inside of the hollow

electrophotographic photoconductor during curing for the

formation of the cross-linked layer and the heating medium exists

inside of the elastic member.

<14> The method for producing an electrophotographic

photoconductor according to <13>, wherein the tensile strength of

the elastic member is 10kg/cm ² to 400kg/cm ² .

<15> The method for producing an electrophotographic

photoconductor according to one of <13> and <14>, wherein JIS-A

hardness of the elastic member is 10 to 100.

<16> The method for producing an electrophotographic

photoconductor according to any one of <13> to <15>, wherein the

thermal conductivity of the elastic member is 0.1W/m-K to lOW/m-

K.

<17> The method for producing an electrophotographic

photoconductor according to any one of <11> to <16>, wherein

during curing for the formation of the cross-linked layer, the hollow

electrophotographic photoconductor is placed so that the length of

the electrophotographic photoconductor is substantially vertical.

<18> The method for producing an electrophotographic

photoconductor according to any one of <11> to <17>, wherein the

heating medium is circulated during curing for the formation of the

cross-linked surface layer in a direction from top to bottom of the

hollow electrophotographic photoconductor.

<19> The method for producing an electrophotographic

photoconductor according to any one of <10> to <18>, wherein the

exposure intensity for light curing is lOOOmW/cm ² or more.

<20> An image forming apparatus including ^: an

electrophotographic photoconductor according to any one of <1> to

<8> ₅ " a latent electrostatic image forming unit to form a latent

electrostatic image on a surface of the electrophotographic

photoconductor; a developing unit configured to develop the latent

electrostatic image using a toner to form a visible image! a

transferring unit configured to transfer the visible image onto a

recording medium; and a fixing unit configured to fix the

transferred image to the recording medium.

<21> An image forming method including ¹ forming a latent

electrostatic image on a surface of an electrophotographic

photoconductor according to any one of <1> to <8>; forming a

visible image by developing the latent electrostatic image using a

toner; transferring the visible image onto a recording medium; and

fixing the visible image to the recording medium.

<22> A process cartridge including- an electrophotographic

photoconductor according to any one of <1> to <8>, and at least one

of a charging unit configured to charge a surface of the

electrophotographic photoconductor, an exposing unit configured to

expose the surface of the exposed photoconductor to form a latent

electrostatic image thereon, a developing unit configured to

develop the latent electrostatic image on the electrophotographic

photoconductor using toner to form a visible image, a transferring

unit, a cleaning unit, and a charge elimination unit.

Brief Description of Drawings

FIG. 1 is a block diagram of potential property evaluation

equipment after exposure.

FIG. 2A is an exemplary schematic sectional view of the

single-layer electrophotographic photoconductor of the present

invention.

FIG. 2B is another exemplary schematic sectional view of

the single-layer electrophotographic photoconductor of the present

invention.

FIG. 3A is an exemplary schematic sectional view of the

laminated electrophotographic photoconductor of the present

invention.

FIG. 3B is another exemplary schematic sectional view of

the laminated electrophotographic photoconductor of the present

invention.

FIG. 4 is an exemplary schematic view of an image forming

apparatus of the present invention.

FIG. 5 is an exemplary schematic view of a process cartridge

of the present invention.

FIG. 6A is a block diagram of a vertical exposing UV lamp

system used in Examples.

FIG. 6B is a block diagram of a horizontal exposing UV lamp

system used in Examples.

Best Mode for Carrying Out the invention

(Electrophotographic Photoconductor)

The electrophotographic photoconductor of the present

invention includes a support, at least a cross-linked surface layer

disposed over the support, and other layers as necessary.

The cross-linked layer is not particularly limited and may

be properly selected according to the application. However, a

laminated photoconductor may include a cross-linked charge

transport layer, a cross-linked surface layer, or the like. A

single-layer photoconductor may suit a cross-linked photosensitive

layer, a cross-linked surface layer, or the like. Of these, the

cross-linked surface layer is particularly preferable to the others.

For the electrophotographic photoconductor, when writing is

conducted under the condition that the image static power is

0.53mW and exposure energy is 4.0erg/cm ² , the difference between

the maximum value of the post-exposure electrical potential and

the minimum value of the post-exposure electrical potential is

within 30V, preferably within 20V, more preferably within 10V.

This leads to obtain an electrophotographic photoconductor that

can have a cross-linked layer having uniform property and

compatibility between wear resistance and stable electrostatic

property for prolonged periods.

If the difference between maximum value and minimum

value is above 30V, uneven density may occur at the time of image

outputting that is easily visible for unevenness of exposed area

potential like half tone. From the viewpoint of wear resistance,

the level of polymerization reaction becomes different from parts

where the post-exposure electrical potential is high to parts where

the post-exposure electrical potential is low, and more specifically,

in parts where exposed area potential is high by promoting

polymerization reaction, the cross-linked surface layer has

property of high hardness, whereas in parts where exposed area

potential is low, hardness becomes low. Therefore, stable wear

resistance cannot be attained under the environment of actual use,

wear volume of parts where hardness is low (parts where exposed

area potential is low) becomes large, indistinctive uneven density

at the initial state becomes clarified over time.

Here, the image static power means exposure that scans in

the main scanning direction only (only polygon mirror rotates) and

does not scan in the vertical scanning direction (photoconductor

does not rotate in the circumferential direction).

For the electrophotographic photoconductor, when writing is

conducted under the condition that the image static power is

0.53mW and exposure energy is 4.0erg/cm ² , the maximum value

(Vmax) of the post-exposure electrical potential is preferably

within -60V, more preferably within -80V. If Vmax exceeds -60V,

polymerization reaction within cross-linked layer may not progress

sufficiently and significant improvement of wear resistance may

not be achieved. Halftone density may be difficult to acquire with

an increase of shrinkage over the thickness of the cross-linked layer.

Here, the post-exposure electrical potential can be measured

using for instance a property evaluation apparatus disclosed in

JP-A No. 2000-275872, which is capable of evaluation of the

sensitivity property of the electrophotographic photoconductor;

however the evaluation apparatus is not limited to this and any

evaluation apparatus which can measure the post-exposure electric

potential can be used.

FIG. 1 shows a configuration example of the property

evaluation apparatus. The property evaluation apparatus for the

electrophotographic photoconductor in FIG. 1 is equipped with a

charging unit 202, an exposure unit 203, and a neutralization unit

204 around a photoconductor 201, is equipped with a surface

potential meter 210 between the charging unit 202 and the

exposure unit 203, is equipped with a surface potential meter 211

between the exposure unit 203 and the neutralization unit 204.

The drum-shaped photoconductor 201 is attached to the

drive mechanism unit so as to be rotatable. The charging unit 202,

the neutralization unit 204, the surface potential meter 210, and

the surface potential meter 211 are installed to a common table so

as to be movable to the circumferential direction, the radial

direction, and the longitudinal direction of the photoconductor 201.

The exposure unit 203 includes a laser writing device, is

movable to the radial direction and the longitudinal direction of

the drum-shaped photoconductor 201 (movable to the

circumferential direction only when the photoconductor is rotated),

wherein the radial direction of the photoconductor 201 is designed

to have an interval by the distance of the photoconductor surface

and the focal length of laser writing fθ lens.

With the property evaluation apparatus having a

configuration as shown in FIG.l, when the sensitivity of the

photoconductor 201 is measured, the surface of the photoconductor

201 is neutralized by a neutralization unit 204 through rotating

the polygon mirror of an exposure unit 203 as well as the

photoconductor 201 at a constant rotating speed, the surface of the

photoconductor 201 is charged until predetermined surface

potential by the charging unit 202 is reached, and laser beam of the

exposure unit 203 is applied to the charged photoconductor 201.

By measuring the surface potential of the charged photoconductor

201 by the surface potential meter 210, by measuring the surface

potential of the exposed photoconductor by the surface potential

meter 211, and by calculating the exposed amount (Reached

energy ) required by potential decay from outer diameter of the

photoconductor, linear speed of the photoconductor, resolution of

the laser scan in the vertical scanning direction, charging time,

deployed position of exposing time and the charging unit in the

circumferential direction, and surface potential of the

photoconductor, the relationship between the calculated exposure

dose and measured exposed potential or electric change amount of

before or after exposure is defined as the sensitivity of

photoconductor.

<Cross-Linked Layer>

The cross-linked layer includes at least a radically

polymerizable compound, and where necessary a cured material of

a cross-linked layer composition containing other ingredient(s).

-Radically Polymerizable Compound-

The radically polymerizable compound preferably contains a

radically polymerizable compound with no charge transport

structure and a radically polymerizable compound with charge

transport structure.

The radically polymerizable compound with charge,

transport structure means a compound which contains no hole

transport structure such as triallyl amine, hydrazone, pyrazoline,

carbazolyl, electron transport structure such as fused polycyclic

quinone, diphenoquinone, and electron attracting aromatic rings

having cyano group or nitro group, etc., and a radically

polymerizable functional group. The radically polymerizable

functional group can be any if the group is radically polymerizable,

i.e., has a carbon-carbon double bond.

Examples of the radically polymerizable functional group

include 1- substituted ethylene functional group and

1,1 -substituted ethylene functional group represented by the

following Formula (a).

(1) Examples of 1-substituted ethylene functional group are

functional groups represented by the following Formula (a). (If

the functional group has no aryl group segment, or arylene group

segment, the functional group is connected to the aryl group

segment or the arylene group segment.

CH ₂ =CH-X ₁ - ( _a ) wherein Xi represents an arylene group such as phenylene

group, naphthylene group, which may be substituted, alkynylene

group which may be substituted, -CO- group, -COO- group, -CON

(R ¹⁰ )- group (wherein R ¹⁰ represents a hydrogen atom, an alkyl

group such as methyl group and ethyl group, ar alkyl group such as

benzyl group, naphthylmethyl group and phenethyl group, or aryl

group such as phenyl group and naphthyl group), or -S- group.

Specific examples of these substituents include vinyl group,

styryl group, 2-methyl-l,3-butadienyl group, vinylcarbonyl group,

acryloyloxy group, acryloylamide group, vinylthioether group.

(2) Examples of 1, 1-substituted ethylene functional group

include those represented by the following Formula (b)

CH ₂ =C(Y)-X ₂ - (b)

wherein Y represents an alkyl group which may be

substituted, aralkyl group which may be substituted, aryl group

such as phenyl group, and naphthyl group which may be

substituted, halogen atom, cyano group, nitro group, alkoxy group

such as methoxy group and ethoxy group, -COOR ¹¹ group (wherein

R ¹¹ represents a hydrogen atom, alkyl group such as methyl group

and ethyl group which may be substituted, aralkyl group such as

benzyl, naphthylmethyl and phenethyl groups which may be

substituted, aryl group such as phenyl group and naphthyl group

which may be substituted), or -CONR ¹² R ¹ S (wherein R ¹² and R ¹³

represent a hydrogen atom, alkyl group such as methyl group and

ethyl group which may be substituted, aralkyl group such as benzyl

group, naphthylmethyl group, and phenethyl group which may be

substituted, aryl group such as phenyl group and naphthyl group

which may be substituted, and may be identical or different), X2

represents a substituent identical to X ₁ in the Formula (a), a single

bond, or alkylene group, provided that at least one of Y and X2 is

oxycarbonyl group, cyano group, alkenylene group, or aromatic

ring.

Specific examples of these substituents include α-chloro

acryloyloxy group, methacryloyloxy group, α-cyanoethylene group,

αrcyanoacryloyloxy group, α-cyanophenylene group,

methacryloylamino group.

Examples of substituents by which the subsituents Xi, X2,

and Y are further substituted include a halogen atom, nitro group,

cyano group, alkyl groups such as methyl group, ethyl group,

alkoxy groups such as methoxy group, ethoxy group, aryloxy

groups such as phenoxy group, aryl groups such as phenyl group,

naphthyl group, and aralkyl groups such as benzyl group, and

phenethyl group.

Among these radically polymerizable functional groups,

acryloyloxy group and methacryloyloxy group are particularly

useful. Compounds having one or more acryloyloxy groups may be

obtained, for example, by ester reaction or ester exchange reaction

using compounds having one or more hydroxy groups in the

molecule, acrylic acid or salt, acrylic acid halide and acrylic acid

ester. Besides, compounds having one or more methacryloyloxy

groups may be obtained similarly. The radically polymerizable

functional group in a monomer having two or more functionalities

may be identical or different. Among these radically

polymerizable functional groups, acryloyloxy group and

methacryloyloxy group are particularly useful. The number of a

radically polymerizable functional group in a single molecule can

be one or more, but the number of a radically polymerizable

functional group is preferably one in general to control internal

stress of the cross-linked surface layer, to easily obtain smooth

surface nature, and to sustain good electric property. By using

charge transport compound having these radically polymerizable

functional groups, both durability improvement and electric

property that is stable for prolonged periods are attained. As

charge transport structure of charge transport compound having a

radically polymerizable functional group, triallyl amine structure

suits from high mobility perspective, and among triallyl amine

structures, compounds shown in the following general Formula (2)

or (3) structure can maintain electric property such as sensitivity

and residual potential in a good condition.

R _l O

Il Ar 3,

CH ₂ = C-CO-(Z)Hi-Ar ₁ - X-Ar ₂ -N ^{' " Ar ₄ (2)}

In Structural Formula (2) and (3), R ₁ represents a hydrogen

atom, a halogen atom, cyano group, nitro group, alkyl group which

may be substituted, aralkyl group which may be substituted, aryl

group which may be substituted, alkoxy group, -COOR ₇ (wherein

R7 represents a hydrogen atom, alkyl group which may be

substituted, aralkyl group which may be substituted, or aryl group

which may be substituted), halogenated carbonyl group, or

CONRδRθ (wherein Rs and R9 each represents a hydrogen atom,

halogen atom, alkyl group which may be substituted, aralkyl group

which may be substituted, or aryl group which may be substituted

and Rs and R9 may be identical or different).

An and Ar2 each represent the substituted or unsubstituted

arylene group which may be identical or different.

Ar3 and Ar4 each represent the substituted or unsubstituted

aryl group, which may be identical or different.

X represents a single bond, substituted or unsubstituted

alkylene group, substituted or unsubstituted cycloalkylene group,

substituted or unsubstituted alkylene ether bivalent group, oxygen

atom, sulfur atom, or vinylene group I Z represents the substituted

or unsubstituted alkylene group, substituted or unsubstituted

alkylene ether bivalent group, or alkyleneoxycarbonyl bivalent

group? ^" "m" and "n" each represents an integer from 0 to 3.

The following are specific examples of compounds

represented by the previous Formulae (2) and (3).

In the substituents of Ri in the general Formulae (2) and (3),

examples of the alkyl groups include methyl group, ethyl group,

propyl group, butyl group, examples of the aryl groups include

phenyl group, naphthyl group, examples of the aralkyl groups

include benzyl group, phenethyl group, naphthylmethyl group,

examples of the alkoxy groups include methoxy group, ethoxy

group, and propoxy group. These groups may be substituted

furthermore with a halogen atom, nitro group, cyano group, alkyl

group such as methyl group, ethyl group etc., alkoxy group such as

methoxy group, ethoxy group, aryloxy group such as phenoxy group,

aryl group such as phenyl group, naphthyl group, aralkyl group

such as benzyl group, phenethyl group.

Hydrogen atom and methyl group are particularly preferable

among substituents of Ri.

Ar3 and Ar ₄ are substituted or unsubstituted aryl groups and

examples of the aryl groups include fused polycyclic hydrocarbon

groups, non-fused cyclic hydrocarbon groups, and heterocyclic

groups.

The fused polycyclic hydrocarbon group is preferably one

having 18 or less carbon atoms for ring formation and examples

thereof include pentanyl group, indenyl group, naphthyl group,

azulenyl group, heptarenyl group, biphenylenyl group,

as-indacenyl group, s-indacenyl group, fluorenyl group,

acenaphthylenyl group, pleiadenyl group, acenaphthenyl group,

phenalenyl group, phenanthryl group, antholyl group,

fluoranthenyl group, acephenanthrylenyl group, aceanthrylenyl

group, triphenylenyl group, pyrenyl group, chrysenyl group, and

naphthacenyl group.

Examples of the non-fused cyclic hydrocarbon groups include

monovalent group for monocyclic hydrocarbon compounds such as

benzene, biphenyl ether, polyethylenediphenyl ether,

diphenylthioether and diphenylsulphone, the monovalent group for

non-fused polycyclic hydrocarbon compounds such as biphenyl,

polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne,

triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane,

polyphenylalkane and polyphenylalkene, or the monovalent group

for cyclic hydrocarbon compounds such as 9,9-diphenylfluorene.

Examples of the heterocyclic groups include monovalent

groups such as carbazole, dibenzofuran, dibenzothiphene,

oxadiazole, and thiadiazole.

The aryl groups represented by Ar3 and Ar ₄ may be

substituted with any of substituent described in (l) to (8) below.

(1) Halogen atom, cyano group, nitro group.

(2) Alkyl groups, preferably straight-chained or branched

alkyl groups of 1 to 12 carbon atoms, more preferably 1 to 8 carbon

atoms, and most preferably 1 to 4 carbon atoms, wherein alkyl

groups may be substituted with a fluorine atom, hydroxy group,

cyano group, alkoxy group for 1 to 4 carbon atoms, phenyl group, or

phenyl group substituted with a halogen atom, alkyl group for 1 to

4 carbon atoms or alkoxy group for 1 to 4 carbon atoms. Specific

examples thereof include methyl group, ethyl group, rrbutyl group,

i-propyl group, t-butyl group, s-butyl group, n-propyl group,

tri-fluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl group,

2-cyanoethyl group, 2-methoxyethyl group, benzyl group,

4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl

group.

(3) Alkoxy groups (-OR2), wherein R2 represents an alkyl

group as described in (2). Specific examples thereof include

methoxy group, ethoxy group, n-propoxy group, i-propoxy group,

t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group,

2-hydroxyethoxy group, benzyloxy group, tri-fluoromethoxy group.

(4) Aryloxy groups

Aryl groups may be phenyl group and naphthyl group, which

may be substituted with alkoxy group for 1 to 4 carbon atoms, alkyl

group for 1 to 4 carbon atoms, or a halogen atom. Specific

examples thereof include phenoxy group, 1-naphthyloxy group,

2-naphthyloxy group, 4-methoxyphenoxy group, 4-methylphenoxy

group .

(5) Alkylmercapto groups or arylmercapto groups

Specific examples thereof include methylthio group,

ethylthio group, phenylthio group, p-methylphenylthio group.

(6) Groups expressed by the following Structural Formula.

R ₃ — N

wherein R3 and B4 each independently represent a hydrogen

atom, alkyl group as described in (2) or aryl group. Examples of

the aryl group include phenyl group, biphenyl group, and naphthyl

group which may be substituted with alkoxy group for 1 to 4 carbon

atoms, alkyl group for 1 to 4 carbon atoms, or a halogen atom. R3

and R4 may form a ring together.

Specific examples thereof include amino group,

diethylamino group, N-methyl-N-phenylamino group,

N,N-diphenylamino group, N, N- di (try 1) amino group,

dibenzylamino group, piperidino group, morpholino group,

pyrrolidino group, .

(7) Alkylenedioxy groups or alkylenedithio groups such as

methylenedioxy group or methylenedithio group..

(8) Substituted or unsubstituted styryl group, substituted or

unsubstituted β-phenylstyryl group, diphenylaminophenyl group,

ditolylaminophenyl group.

The arylene groups represented by Ar ₁ . and Ar2 include

divalent groups derived from aryl groups represented by Are and

X represents a single bond, substituted or unsubstituted

alkylene group, substituted or unsubstituted cycloalkylene group,

substituted or unsubstituted alkylene ether group, oxygen atom,

sulfur atom, or vinylene group.

Examples of the substituted or unsubstituted alkylene

groups are preferably straight-chain or branched-chain alkylene

groups of 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and

more preferably 1 to 4 carbon atoms. The alkylene groups may be

further substituted with a fluorine atom, hydroxy group, cyano

group, and alkoxy groups of 1 to 4 carbon atoms, phenyl group, or

phenyl group substituted with a halogen atom, alkyl group for 1 to

4 carbon atoms, or alkoxy group for 1 to 4 carbon atoms. Specific

examples thereof include methylene group, ethylene group,

n-butylene group, i-propylene group, t-butylene group, s-butylene

group, n-propylene group, trifluoromethylene group,

2-hydroxyethylene group, 2-ethoxyethylene group, 2-cyanoethylene

group, 2-methoxyethylene group, benzylidene group,

phenylethylene group, 4-chlorophenylethylene group,

4-methylphenylethylene group, 4-biphenylethylene group.

Examples of the substituted or unsubstituted cycloalkylene

groups include cyclic alkylene groups of 5 to 7 carbon atoms,

wherein the cyclic alkylene groups may be substituted with a

fluorine atom, hydroxide group, alkyl group for 1 to 4 carbon atoms,

or alkoxy group for 1 to 4 carbon atoms. Specific examples thereof

include cyclohexylidene group, cyclohexylene group,

3,3- dimethylcy clohexylidene group .

Examples of the substituted or unsubstituted alkylene ether

bivalent group include alkyleneoxy bivalent group such as

ethyleneoxy group, propyleneoxy group, di or poly (oxyalkylene)

oxy bivalent group induced from such as diethylene glycol,

tetraethylene glycol, tripropylene glycol, wherein alkylene ether

bivalent group and alkylene group may be substituted with

hydroxyl group, methyl group, ethyl group.

The vinylene group may be represented by the following

Formula.

or

In the Structural Formula, Rs represents a hydrogen atom,

alkyl group that is identical to the one described in (2), or aryl

group that is identical to the one represented by the Ar3 and the

Ar45 "a" represents an integer of 1 or 2, and "b" represents an

integer of 1 to 3.

Z represents the substituted or unsubstituted alkylene

group, substituted or unsubstituted alkylene ether bivalent group,

or alkyleneoxycarbonyl bivalent group. The substituted or

unsubstituted alkylene groups include alkylene groups defined as

X. The substituted or unsubstituted alkylene ether bivalent

groups include alkylene ether bivalent groups defined as X. The

alkyleneoxycarbonyl bivalent groups include caprolactone-modified

bivalent groups.

Examples of the preferable radically polymerizable

compounds with charge transport structure include compounds

which have the structure of the following Structural Formula (4).

In the Structural Formula (4), "o," "p", and "q" each

represents an integer of 0 or 1, Ra represents a hydrogen atom or

methyl group, Rb and Rc may be identical or different, and

represent alkyl groups of 1 to 6 carbon atoms, "s" and "t" each

represents an integer of 0 to 3, and Za represents a single bond,

methylene group, ethylene group, or groups expressed by the

following Formulas '■

In compounds represented by the Structural Formula (4),

substituents of Rb and Rc are preferably a methyl group or an ethyl

group.

The radically polymerizable compounds with charge

transport structure represented by the Structural Formulae (l), (2),

and (3), particularly those represented by the Structural Formula

(4) become incorporated into continuous polymer chains instead of

being a terminal structure because polymerization is accomplished

by opening a carbon-carbon double bond at both sides. The

radically polymerizable compounds exist within cross-linked

polymers formed with radically polymerizable monomers having

three or more functionalities as well as in the cross-linking chain

between main chains. This cross-linking chain contains

intermolecular cross-linking chains between a polymer and other

polymers, and intermolecular cross-linking chains between parts

which have folded main chains within a polymer and other parts

which originate from monomers polymerized in distant positions

from the parts in the main chain. Whether radically

polymerizable compounds having single functionality exist in the

main chain or the cross-linking chain, the triarylamine structure

attached to the chain having at least three aryl groups placed in a

radial direction from the nitrogen atom is bulky; however, three

aryl groups are not directly attached to the chains; instead they are

indirectly attached to the chains through carbonyl group or the like,

so that triarylamine structure is fixed flexibly in

three-dimensional arrangement. Because the triarylamine

structure has appropriate configuration within a molecule, it is

presumed that the intramolecular structural strain is less and

intramolecular structure can relatively escape the disconnection of

charge transport path in the cross-linked surface layer of

photoconductors.

Besides, in the present invention, specific acrylic acid ester

compound represented in the following general Formula (5) may

suit in use as a radically polymerizable compound with charge

transport structure.

In the general Formula (5), Are represents a monovalent or

bivalent group having substituted or unsubstituted aromatic

hydrocarbon skeleton. Examples of aromatic hydrocarbons

include benzene, naphthalene, phenanthrene, biphenyl,

1,2,3,4-tetrahydronaphthalene.

Examples of substituent group include alkyl group of 1 to 12

carbon atoms, alkoxy group of 1 to 12 carbon atoms, benzyl group,

and a halogen atom. The alkyl group, alkoxy group may further

have halogen atom, and/or phenyl group as substituent group.

Are represents a monovalent or bivalent group having

aromatic hydrocarbon skeleton with at least one tert-amino group,

or monovalent or bivalent group having heterocyclic compound

skeleton with at least one tert- amino group. The following

general Formula (A) represents an aromatic hydrocarbons skeleton

having the tert-amino group.

In the general Formula (A), R13 and Ei4 represent an acyl

group, substituted or unsubstituted alkyl group, substituted or

unsubstituted aryl group. Ar ₇ represents an aryl group, and "w"

represents an integer from 1 to 3.

Examples of acyl groups of Ri3 and R ₁₄ include acetyl group,

propionyl group, and benzoyl group.

Substituted or unsubstituted alkyl groups of Ri3, Ru are

similar to those for Ars-

Examples of the substituted or unsubstituted aryl groups for

Ri3 and R ₁₄ include phenyl group, naphthyl group, biphenylyl

group, tert-phenylyl group, pyrenyl group, fluorenyl group,

9,9"dimethyl-2"fluorenyl group, azulenyl group, antholyl group,

triphenylenyl group, chrysenyl group, and functional group

represented by the following general Formula (B).

In the general Formula (B), B represents -O, -S-, -SO-, -SO2-,

^■ CO-, or bivalent group represented by the following Formula.

In the Formula, R21 represents a hydrogen atom, substituted

or unsubstituted alkyl group defined in Ars, alkoxy group, halogen

atom, substituted or unsubstituted aryl group defined in Ri3,

amino group, nitro group, and cyano group. R22 represents a

hydrogen atom, substituted or unsubstituted alkyl group defined in

Ars, and substituted or unsubstituted aryl group defined in Ri3, "i"

represents an integer of 1 to 12, and "j" represents an integer of 1

to 3.

Examples of alkoxy groups for R21 include methoxy group,

ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group,

i-butoxy group, s-butoxy group, t-butoxy group, 2 -hydroxy ethoxy

group, 2-cyanoethoxy group, benzyloxy group, 4-methylbenzyloxy

group, trifluoromethoxy group.

Examples of halogen atom for R21 include fluorine atom,

chlorine atom, bromine atom, iodine atom.

Examples of amino groups for R21 include diphenylamino

group, ditorylamino group, dibenzylamino group, 4-methylbenzyl

group.

Examples of aryl group for Ar ₇ include phenyl group,

naphthyl group, biphenylyl group, tert-phenylyl group, pyrenyl

group, fluorenyl group, 9,9-dimethyl-2-fluorenyl group, azulenyl

group, antholyl group, triphenylenyl group, chrysenyl group, .

Ar ₇ , Ri3, and Hu may be substituted with the alkyl group,

alkoxy group, halogen atom defined in Ars.

Examples of the heterocyclic compound skeleton having a

tert-amino group include heterocyclic compounds having amine

structure such as pyrrol, pyrazole, imidazole, triazole, dioxyazole,

indole, isoindole, benzimidazole, benzotriazole, benzoisoxazine,

carbazolyl, phenoxazine. These may have alkyl group, alkoxy

group, and a halogen atom defined in Ars as a substituent group.

In the general Formula (5), Bi and B2 each represents

acryloyloxy group, methacryloyloxy group, vinyl group, acryloyloxy

group, methacryloyloxy group, alkyl group having vinyl group,

acryloyloxy group, methacryloyloxy group, and alkoxy group

having vinyl group. Alkyl group and alkoxy group are applied to

the Ars aforementioned likewise. Note in the formula that either

Bi or B2 appears? ^' they do not appear at the same time.

In the acrylic acid ester compound shown in the general

Formula (5), compounds represented by the following general

Formula (6) are preferable.

In the general Formula (6), Rs and R9 each represent the

substituted or unsubstituted alkyl group, substituted or

unsubstituted alkoxy group, and a halogen atom. Ar ₇ and Ars

each represents the substituted or unsubstituted aryl group,

arylene group, substituted or unsubstituted benzyl group. Alkyl

group, alkoxy group, and a halogen atom are applied to the Ars

aforementioned likewise.

The aryl group is aryl group defined in R13, Ru likewise.

The arylene group is bivalent group induced from the aryl group.

Bi to B4 are Bi, B2 of the general Formula (5) likewise.

Out of Bi to B4, only one of four exists and existence of two or more

is excluded, "u" represents an integer of 0 to 5 and "v" represents

an integer of 0 to 4.

The specific acrylic acid ester compounds have the following

feature. It is a tert-amine compound having conjugate structure

of stilbene type and has a developed conjugate system. Using the

developed charge transport compound of the conjugate system,

charge injection property of the cross-linked layer interface

improves remarkably, and in case of cross-linking bond being fixed,

intermolecular interaction is hardly interrupted, which charge

mobility is in a good condition as well. It also has a highly

radically polymerizable acryloyloxy group, or methacryloyloxy

group within a molecule, promotes gelation promptly at the time of

radical polymerization, and does not yield extreme cross-linking

strain. Double bonds of stilbene part within molecules join partly

polymerization. In addition, because polymerization property is

lower than that of acryloyloxy group, or methacryloyloxy group, it

prevents maximum strain from occurring by the time difference in

cross-linking reaction. Furthermore, because it is possible to

increase the number of cross-linking reactions per molecular

weight by using a double bond within a molecule, it is possible to

increase the cross-link density and attain further improvement of

wear resistance. The double bond can adjust degree of

polymerization according to cross-linking condition, so that it can

produce optimal cross-linked layer easily. The cross-linking

participation to radical polymerization is a specific property to

acrylic acid ester compound, and does not happen in the described

α-phenyl stilbene type structure.

From the above, the use of a radically polymerizable

compound with charge transport structure shown in the general

Formula (5), especially the general Formula (6), maintains

superior electric property, can form a film of extreme high

cross-link density without involving cracking, whereby it is

possible to satisfy the properties of the photoconductor, to prevent

fine silica particles from sticking to the photoconductor, and to

reduce the occurrence of image failures such as white dots.

The following are non-exclusive examples of the radically

polymerizable compounds with charge transport structure, which

are used in the present invention.

Table 1-1

Table 1-2

Table 1-3

Table 1-4

Table 1-10

Table 1-11

Table 1-12

<Exarαples of Synthesizing Method for Monofunctional Radically

Polymerizable Compound 1 with Charge Transport Structure>

Examples of the synthesizing method for the compound

having a charge transport structure according to the present

invention include a method disclosed in JP-B No. 3164426. An

example thereof is shown as follows. The method for Example

includes the following two steps (l) and (2).

(l) Synthesis of Hydroxy Group -Substituted Triarylamine

Compound (represented by the following Formula (B'))

To 240ml of sulfolane was added 113.85g of a methoxy

group -substituted triarylamine (represented by the following

Formula (A')) and 138g (0.92mol) of sodium iodide, and the

resultant mixture was heated at 60 ⁰ C in a nitrogen gas stream.

To the mixture, 99g (0.91mol) of trimethylchlorosilane was added

dropwise over Ih and the mixture was stirred at about 60°C for

4.5h, thereby completing the reaction. The reaction mixture was

mixed with about 1.5L of toluene and the resultant solution was

cooled to room temperature, followed by washing the solution

repeatedly with water and an aqueous solution of sodium

carbonate. Thereafter, from the toluene solution, the solvent was

distilled off and the resultant residue was purified by column

chromatography (adsorption medium.: silica gel, developing

solvent: mixture of toluene and ethyl acetate in a mixing ratio

(toluene^ ethyl acetate) of 20^1), thereby obtaining an oily

substance. The obtained light-yellow oily substance was mixed

with cyclohexane and crystals were precipitated, thereby obtaining

88.1g (yield = 80.4%) of white crystals of a compound represented

by the following Formula (B'). The compound has the melting

point of 64.0°C to 66.0°C.

Table 2

Each value of the Table 2 represents an elemental analysis

(2) Triarylamino Group - Substituted Acrylate Compound

(Example Compound No. 1 in Table l-l)

In 400ml of tetrahydrofuran was dissolved 82.9g (0.227mol)

of a hydroxyl group -substituted triarylamine compound

(represented by Formula (B')) obtained in (l), and to the resultant

solution, an aqueous solution of sodium hydroxide (prepared by

dissolving 12.4g of sodium hydroxide in 100ml of water) was added

dropwise in a nitrogen gas stream. The resultant solution was

cooled to 5°C and to the solution, 25.2g (0.272mol) of acrylic acid

chloride was added dropwise over 40min, followed by stirring at

5°C for 3hr, thereby completing the reaction. The reaction

product solution was mixed with water and the resultant mixture

was extracted with toluene. The extract was washed repeatedly

with an aqueous solution of sodium bicarbonate and water.

Thereafter, from the toluene solution, the solvent was distilled off

and the resultant residue was purified by a column

chromatography (adsorption medium- silica gel, developing

solvent'- toluene), thereby obtaining an oily substance. The

obtained colorless oily substance was mixed with n-hexane and

crystals were precipitated, thereby obtaining 80.73g (yield =

84.8%) of white crystals of the compound No. 1 in Table 1-1. The

compound has the melting point of 117.5°C to 119.0 ⁰ C.

Table 3

Each, value of the Table 3 represents an elemental analysis

value in percentile.

(3) Synthesis example of acrylic acid ester compound

(Preparation of 2-hydroxybenzylphosphonatediethyl)

To a reaction vessel equipped with an agitation device, a

thermometer and a dripping funnel was added 38.4g of

2-hydroxybenzylalcohol (by Tokyo Chemical Industry Co., Ltd.) and

80ml of o-χylene and 62.8g of triethyl phosphate (by Tokyo

Chemical Industry Co., Ltd.) was slowly added dropwise at 80 ⁰ C in

a nitrogen gas stream for lhr reaction at the same. Thereafter,

the produced ethanoL o-χylene solvent, and unreacted triethyl

phosphate were removed by reduced-pressure distillation, thereby

obtaining 66g of 2-hydroxybenzylphosphonatediethyl (boiling point

= 120.0°C/1.5mmHg) (yield = 90%).

(Preparation of

2-hydroxy-4'-(N,N-bis(4-methylphenyl)amino)stilbene)

To a reaction vessel equipped with an agitation device, a

thermometer and a dripping funnel was added 14.8g of potassium

tert-butoxide and 50ml of tetrahydrofuran, and an aqueous

solution of tetrahydrofuran in which 9.9Og of

2-hydroxybenzylphosphonic acid diethyl and 5.44g of

4-(N,N-bis(4-methylphenyl)amino) benzaldehyde were dissolved

was slowly added dropwise to the reaction vessel at room

temperature in a nitrogen gas stream, followed by 2hr reaction at

the same temperature. The resultant solution was cooled, added

with water, and added with 2N hydrochloric acid solution for

acidification. Thereafter, tetrahydrofuran was removed by an

evaporator, and the crude product was extracted with toluene.

The toluene phase was sequentially washed with water, sodium

hydrogen carbonate solution and saturated saline, and dehydrated

by the addition of magnesium sulfate. After filtration, toluene

was removed to obtain an oily crude product. Then the oily crude

product was purified by column chromatography on silica gel,

crystallized in hexane, thereby obtaining 5.09g of 2-hydroxy4'-(N,

N-bis(4-methylphenyl)amino)stilbene (yield = 72%, melting point =

136.0 ⁰ C to 138.0 ⁰ C).

(Preparation of

4'-(N,N-bis(4-methylphenyl)amino)stilbene2-ylacrylate)

To a reaction vessel equipped with an agitation device, a

thermometer and a dripping funnel was added 14.9g of

2-hydroxy4'-(N, N-bis(4-methylphenyl)amino)stilbene, 100ml of

tetrahydrofuran and 21.5g of 12% sodium hydroxide solution, and

to the resulting solution, 5.17g of acrylic chloride was added

dropwise at 5°C over 30min in a nitrogen gas stream, followed by

reaction for 3hr at the same temperature. The reaction solution

was immersed in water, was subject to toluene extraction, and then

purified by column chromatography on silica gel. The obtained

crude product was re -crystallized with ethanol, thereby obtaining

13. δg of yellow colored, needle-shape crystal

4'-(N,N-bis(4-methylphenyl)amino)stilbene2-ylacrylate (Example

compound No. 34) (yield = 79.8%, melting point = 104.1 ⁰ C to

105.2 ⁰ C).

Results of element analysis are as follows^

Table 4

Each value of the Table 4 represents an elemental analysis

value in percentile.

From the above, by reacting 2-hydroxybenzylphosphonate

ester derivatives and various amino -substituted benzaldehyde

derivatives, many 2-hydroxystilbene derivatives can be

synthesized, and by acrylation or methacrylation of these, various

acrylic acid ester compounds can be synthesized.

In the electrophotographic photoconductor of the present

invention, using a radically polymerizable compound with charge

transport structure and the radically polymerizable compound

with no charge transport structure is preferable. The radically

polymerizable compound with charge transport structure employed

in the present invention is essential for providing a cross-linked

surface layer with charge transport ability. The content of

radically polymerizable compounds is preferably 20% by mass to

80% by mass, more preferably 30% by mass to 70% by mass, based

on the total mass of a cross-linked surface layer. When the

content is below 20% by mass, charge transport property of a

cross-linked surface layer may not be sufficiently maintained, and

causes deterioration of electric property such as sensitivity

reduction and residual potential increase under repeated usages.

When the content of radically polymerizable compounds having

single functionality is more than 80% by mass, the content of

radically polymerizable monomers having three or more

functionalities may become inevitably deficient, reducing the

cross-link density and causing insufficient wear resistance.

Although required electric property and wear resistance differ

depending on the processes, and there is no specific mass

percentage, the content of radically polymerizable compounds is

particularly preferably 30% by mass to 70% by mass when the

balance of two properties is considered.

Example of the radically polymerizable compound with no

charge transport structure includes a radically polymerizable

compound with charge transport structure having a radically

polymerizable functional group. As the radically polymerizable

functional group, acryloyloxy group, and methacryloyloxy group

are preferable. From the viewpoint of the improvement of wear

resistance, radically polymerizable monomers having three or more

of radically polymerizable functional groups of acryloyloxy group,

or methacryloyloxy group suit in use.

A compound having three or more acryloyloxy groups can be

obtained by ester reaction or ester exchange reaction using a

compound having three or more hydroxyl groups within a molecule

for instance, and acrylic acidate, acrylic halide, and acrylic ester.

A compound having three or more methacryloyloxy groups can be

obtained likewise. A radically polymerizable functional group in

monomer having three or more a radically polymerizable functional

groups may be identical or different.

Specific examples of radically polymerizable monomers

having three or more functionalities with no charge transport

structure are not limited, and are properly selected according to

the application but include trimethylol propane triacrylate

(TMPTA), trimethylol propane trimethacrylate,

HPA-modified-trimethylol propane triacrylate,

EO-modified-trimethylol propane triacrylate,

PO-modified-trimethylol propane triacrylate,

caprolactone-modified-trimethylol propane triacrylate,

HPA-modified-trimethylol propane trimethacrylate,

pentaerythrytoltriacrylate, pentaerythrytoltetracrylate (PETTA),

glyceroltriacrylate , E CH-modifie d- glyceroltriacrylate ,

EO-modified-glyceroltriacrylate, PO-modified-glyceroltriaerylate,

tris(acryloxyethyl)isocyanurate, dipentaerythrytolhexaacrylate

(DPHA), caprolactone-modified-dipentaerythrytolhexaacrylate,

dipentaerythrytolhydroxypentacrylate,

alkyl-modified-dipentaerythrytolpentacrylate,

alkyl-modified-dipentaerythrytoltetracrylate,

alkyl-modified-dipentaerythrytoltriacrylate,

dimethylolpropanetetracrylate (DTMPTA),

pentaerythrytolethoxytetracrylate,

EO-modified-phosp hate triacrylate,

2,2,5, δ-tetrahydroxymethylcyclopentanonetetracrylate. These

radically polymerizable monomers may be used alone or in

combination.

As the radically polymerizable monomer having three or

more functionalities with no charge transport structure, to form

densely spaced cross-linking bonds in the cross-linked layer, the

ratio of molecular weight to the number of functional groups in the

monomer (molecular weight/number of functional group) is

preferably 250 or less. If this ratio exceeds 250, a cross-linked

surface layer becomes soft and wear resistance drops to some

extents. Thus, using an extremely long group alone is not

preferable in a monomer having modified group such as HPA, EO,

and PO of the exemplified monomer.

The content of the radically polymerizable monomer having

three or more functional groups with no charge transport structure,

which is used for the cross-linked layer, 20% by mass to 80% by

mass is preferable relative to the total amount of the cross-linked

layer, 30% by mass to 70% by mass is more preferable. If the

content of the monomer is below 20% by mass, a three-dimensional

cross-linking bond density of the cross-linked layer becomes small,

and compared to the case of using a traditional thermoplastic

binder resin, significant improvement of wear resistance is not

achieved. If the content of the monomer is above 80% by mass,

the content of a charge transport compound is reduced and

deterioration of electric property may occur. There is no specific

answer because wear resistance and electric property required for

used process are different, but considering the balance of both

properties, range of 30% by mass to 70% by mass is particularly

preferable.

The cross -linked layer is formed by light-curing at least a

radically polymerizable compound. Furthermore, radically

polymerizable monomers, functional monomers, and radically

polymerizable oligomers having one or two functionalities may be

used simultaneously for viscosity control during coating, stress

relief of a cross-linked surface layer, surface energy degradation,

and friction coefficient reduction. Known monomers and

oligomers can be used.

Examples of radical monomers having single functionality

include 2-ethylhexyl acrylate, 2 -hydroxy ethyl acrylate,

2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate,

2-ethylhexylcarbitol acrylate, 3-methoxybutyl acrylate, benzyl

acrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate,

methoxytriethyleneglycol acrylate, phenoxytetraethyleneglycol

acrylate, cetyl acrylate, isotearyl acrylate, stearyl acrylate, styrene

monomer.

Examples of chain polymerizable monomers having two

functionalities include 1,3-butanediol diacrylate, 1,4-butanediol

diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol

diacrylate, 1,6-hexanediol dimethacrylate, die thy lene glycol

diacrylate, neopentylglycol diacrylate, EO-modified bisphenol B

diacrylate, EO-modified bisphenol F diacrylate,

neopentylglycoldiacrylate .

Examples of functional monomers include fluorinated

monomers such as octafluoropentylacrylate, 2-perfluorooctylethyl

acrylate, 2-perfluorooctylethyl methacrylate,

2-perfluoroisononylethyl acrylate, ; vinyl monomers, acrylate and

methacrylate having polysiloxane group such as

acryloylpolydimethylsiloxaneethyl,

methacryloylpolydimethylsiloxaneethyl,

acryloylpolydimethylsiloxanepropyl,

acryloylpolydimethylsiloxanebutyl,

diacryloylpolydimethylsiloxane diethyl, which have 20 to 70

siloxane repeating units, as described in Japanese Patent

Application Publication (JP-B) Nos. 05-60503 and 06-45770.

Examples of chain polymerizable oligomers include epoxy

acrylates, urethane acrylates, and polyester acrylate oligomers.

However, if the large content of monofunctional and bifunctional

radically polymerizable monomer and radically polymerizable

oligomer are contained, a three-dimensional cross-linking bond

density of a cross-linked surface layer degrades substantially,

resulting wear resistance degradation. For this reason, the

content of these monomers or oligomers is preferably 50 parts by

mass or less and more preferably 30 parts by mass or less relative

to 100 parts by mass of radically polymerizable monomers having

three or more functionalities.

The cross-linked layer is formed by light-curing of at least a

radically polymerizable compound; however, a polymerization

initiator may be used to progress this cross-linking reaction

efficiently as necessary. The polymerization initiator may be any

of heat polymerization initiators and photopolymerization

initiators.

Examples of the thermal polymerization initiator include

peroxides such as 2,5-dimethyl hexane-2,5-dihydro peroxide,

diqumyl peroxide, benzoyl peroxide, t-butylqumyl peroxide,

2,5-dimethyl-2,5-di(peroxybenzoyl)hexane-3, di-t-butyl beroxide,

t-butyl hydroberoxide, cumene hydroberoxide, lauroyl peroxide, etc.

and azo compounds such as azobis isobutylnitrile,

azobiscyclohexane carbonitrile, azobisisobutyricmethyl,

azobisisobutylamidin hydrochloride, 4,4-azobis-4-cyanovaleric

acid.

Examples of the photopolymerizable initiators are not

limited, and can be properly selected according to the application,

but include acetophenone photopolymerizable initiators, ketal

photopolymerizable initiators, benzoinether photopolymerizable

initiators, benzophenone photopolymerizable initiators,

thioxanthone photopolymerizable initiators, and other

photopolymerizable initiators. These may be used alone or in

combination.

Examples of acetophenone, ketal photopolymerization

initiators include diethoxyacetophenone,

2,2-dimethoxy-l,2-diphenyletlian-l-one,

l-hydroxy-cyclohexyl-phenyl-ketone,

4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl) ketone,

2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)butanone"l ,

2-hydroxy-2-methyl-l-phenylpropane-l-one,

2-methyl-2-morpholino(4-methyltliiophenyl)propane-l-one, and

l-phenyl-l,2-propanedione-2-(o-ethoxycarbonyl)oxime.

Examples of benzoinether photopolymerization initiators

include benzoin, benzoinmethyl ether, benzoinethylether,

benzoinisobutylether, and benzoinisopropyl ether.

Examples of benzophenone photopolymerization initiators

include benzophenone, 4-hydroxybenzophenone, methyl

o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl,

4-benzoylphenylether, acrylated benzophenone, and

1 , 4-benzoylbenzene .

Examples of thioxanthone photopolymerization initiators

include such as 2-isopropylthioxanthone, 2-chlorothioxanthone,

2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and

2, 4- dichlorothioxanthone .

Examples of other photopolymerization initiators include

ethylanthraquinone, 2,4,6"trimethylbenzoyldiphenylphosphine

oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide,

bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,

bis(2,4-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,

methylphenylglyoxyester, 9,10-phenantlirene compounds, acridine

compounds, triazine compounds, imidazole compounds.

Besides, compounds that have photopolymerization

promoting effect can be employed alone or together with the

photopolymerization initiators described above?" examples of

photopolymerization promoters include triethanolamine,

methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl

4-dimethylaminobenzoate, (2-dimethylamino)ethylbenzoate,

4, 4 ¹ " dimethylaminobenzophenone .

The content of the polymerization initiator is preferably 0.5

parts by mass to 40 parts by mass; more preferably 1 part by mass

to 20 parts by mass per 100 parts by mass of the total amount of

the entire radically polymerizable compounds.

The coating solution for a cross-linked surface layer of the

present invention may contain various additives such as

plasticizers for the purpose of relieving stress and improving

adhesion, leveling agents, non-reactive lowmolecular charge

transport materials, as necessary. Known coating solution may be

used. Plasticizers usable in the present invention include those

commonly used for conventional resins such as dibutylphthalate,

dioctylphthalate. The added amount is preferably 20% by mass or

less, more preferably 10% by mass or less based on the total solid

content of coating solution.

Examples of leveling agents include silicone oils such as

dimethyl silicone oil, methylphenyl silicone oil, and polymers or

oligomers having perfluoroalkyl group in the side chain. The

added amount of leveling agent is preferably 3% by mass or less.

(Method for Producing an Electrophotographic Photoconductor)

The method for producing an electrophotographic

photoconductor of the present invention is the method to produce

the electrophotographic photoconductor of the present invention,

and at least contains a cross-linked layer forming step in which at

least a radically polymerizable compound is cured by irradiation

with light, further contains additional step(s) as necessary.

<Cross-Linked Layer Forming Step>

The cross-linked layer forming step is to cure a radically

polymerizable compound by irradiation with light to form a

cross-linked layer.

In the cross-linked layer forming step, a cross-linked layer is

formed by preparing a coating solution containing at least a

radically polymerizable compound, applying the coating solution

over the surface of the photoconductor, and by irradiating the

coating solution with light for polymerization.

The coating solution may be diluted with solvent as

necessary before being applied. For the solvent, those with a

saturated vapor pressure of 100mmHg/25°C or less are preferable

in view of improving the adhesiveness of the cross-linked layer.

By using such a solvent, the amount of desolvation is reduced at

the time of forming a coated film of the cross-linked surface layer

for an instance, thereby swelling or some degree of dissolution of a

lower layer, a photosensitive layer surface, may occur, an area

having continuousness in the interface neighborhood of a

cross-linked surface layer and a photosensitive layer is formed

presumptively. By forming these layers, an area involving rapid

property change between a cross-linked surface layer and a

photosensitive layer disappears, adhesiveness is retained more

than satisfactory, and to maintain high durability over the total

area of the cross-linked surface iayer becomes possible.

In the present invention, due to the presence of small

solvent in the coated film at the time of forming the coated film,

radical reactions in the cross-linked layer was progressed by

solvent. As a result, the electrophotographic photoconductor that

became possible to improve even-curing over the entire

cross-linked layer was attained. By diluting the coating solution

with a solvent whose saturated vapor pressure is 100mmHg/25°C

or less, it succeeded in obtaining an electrophotographic

photoconductor having stable electric property for prolonged

periods, wherein the internal stress of the inside cross-linked layer

was not locally stored, even cross-linked layer with no strain could

be formed, and the electrophotographic photoconductor maintained

high durability over the total area of the cross-linked layer and

generated no cracking by securing adhesiveness more than

satisfactory.

The saturated vapor pressure of solvent is preferably

50mmHg/25°C or less, more preferably 20mmHg/25°C or less from

the viewpoint of the residual solvent amount in the coated film at

the time of forming a coated film. It is thought as similar

saturated vapor pressure effect, but in case that the boiling point

of solvent is 60 ⁰ C to 150 ⁰ C, a continuous domain of a cross-linked

surface layer and a lower layer, a photosensitive layer can be well

formed, and adhesiveness can be sufficiently secured. Considered

desolvation step like drying by heating, the boiling point of the

solvent is more preferably 100 ⁰ C to 13O ⁰ C. Of the solvent, the

dissoluble parameter is preferably 8.5 to 11.0, more preferably 9.0

to 9.7. By this, affinity of polycarbonate that is the main

constituent material of a lower layer, a photosensitive layer of a

cross-linked surface layer for the coating solution becomes high,

the compatibility of each constituent material with the other

materials improves in the interface of the cross-linked surface

layer and the photosensitive layer, and forming a cross-linked

surface layer that can retain sufficient adhesiveness becomes

possible.

Examples of the solvent include hydrocarbon solvents such

as heptane, octane, trimethylpentane, isooctane, nonane,

2,2,5-trimethylhexane, decane, benzene, toluene, xylene,

ethylbenzene, isopropylbenzene, styrene, cyclohexane,

methylcyclohexane, ethylcyclohexane, cyclehexene, alcohol

solvent such as methanol, ethanol, 1-propanol, 2-propanol,

1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol,

1-pentanol, 2-pentanol, 3-pentanol, 2-methyl- 1-butanol, tert-pentyl

alcohol, 3-methyl-l-butanol, 3-methyl- 1-butanol,

3-methyl-2"butanol, neopentyl alcohol, 1-hexanol,

2-methyl- 1-pentanol, 4-methyl-2-pentanol, 2-ethyll-butanol,

3-heptanol, allylalcohol, propargylalcohol, benzylalcohol,

cyclohexanol, 1,2-ethanodiol, 1,2-propanediol, phenol solvents such

as phenol, creson, ester solvents such as dipropylether,

diisopropylether, dibutylether, butylvinylether, benzylethylether,

dioxane, anisole, phenetol 1,2-epoxybutane, acetal solvents such as

acetal, 1, 2 -dimethoxy ethane, 1,2-dietoxyethane, ketone solvents

such as methylethylketone, 2-pentanone, 2-hexanone, 2-heptanone,

diisobutylketone, methyloxide, cyclohexanone,

methylcyclohexanone, ethylcyclohexanone, 4-methyl-2-pentanone,

acetylacetone, acetonylacetone, esther solvents such as ethyl

acetate, propyl acetate, butyl acetate, penpyl acetate,

3-methoxybutylacetate, diethyl carbonate, 2-methoxyethylacetate,

halogene solvents such as chlorobenzene, sulfuric compound

solvents such as tetrahydrothiophene, solvents having multi

functional group such as 2-methoxyethanol, 2-ethoxyethanol,

2-butoxyethanol, furfurylalcohol, tetrahydolfurfurylalcohol,

l-methoxy-2-propanol, l-ethoxy-2-propanol, diacetonealcohol,

furfural, 2-methoxyethylacetate, 2-ethoxyethylacetate, propylene

glycol propylether, propylene glycol-l-monomethylether-2-acetate.

These solvents may be used alone or in combination. Of these

solvents, butyl acetate, chlorobenzene, acetylacetone, xylene,

2-methoxyethyl acetate, propylene

glycol-l-monomethylether2-acetate, cyclohexanone are

particularly preferable from the viewpoint of adhesiveness.

The dilution ratio of coating solution depends on the

solubility of the cross-linked layer, the coating method, desired

film thickness, and may be properly selected according to the

application, but the solid concentration of the coating solution is

preferably 25% by mass or less, more preferably 3% by mass to 15%

by mass from the perspective of giving sufficient adhesiveness to

the cross-linked layer while maintaining residual solvent volume

on the coated film at the time of forming the coated film.

Coating methods of the coating solution are not limited, can

be properly selected according to the application. Examples of

coating method include dipping, spray coating, bead coating, ring

coating. Of these, spray coating that can adjust the proper

amount of residual solvent in coated film over coating is

particularly preferable.

After the coating solution for a cross-linked surface layer is

applied, it is cured by exposure to external energy to form a

cross-linked surface layer. In order to attain an uniformed

cross-linked layer of which the difference between maximum value

and minimum value of the post-exposure electrical potential is

within 30V when writing is conducted under the condition that the

image static power is 0.53mW and the exposure energy is

4.0erg/cm ² , the difference of maximum and minimum surface

temperature of photoconductor under light exposure should be

within 30°C, is preferable within 20 ⁰ C, is more preferable within

10 ⁰ C.

Besides, in order to promote a polymerization reaction

promptly, the surface temperature of the photoconductor at the

time of exposing is preferably 2O ⁰ C to 170 ⁰ C, more preferably 30 ⁰ C

to 130 ⁰ C. Furthermore, in order to promote polymerization

reaction more efficiently, an increase by 1O ⁰ C or more in the

surface temperature of the photoconductor in 30sec after exposure

initiation is important. As long as the surface temperature of

photoconductor can be maintained within the range, any method

may be applicable, but method for controlling temperature using a

heating medium is preferable. That is, in case that the

photoconductor has drum-shaped hollow support; there is a method

for enclosing a heating medium inside of the drum-shaped hollow

support and circulating the heating medium. Instead of the

drum-shaped, an endless belt type hollow support may also be used.

In this case, controlling the temperature of the heating medium in

order to control the surface temperature of the photoconductor is

preferable. Although any method may be used to achieve the

desired temperature, the method for controlling the temperature

outside the hollow is preferable to the method for controlling

temperature inside the hollow for easy-to-use. Various methods

for spreading a heating medium inside the hollow can be used, but

the method for providing multiple inlets through which the heating

medium enters to the inside of the hollow and a method having a

mechanism or member of agitating a heating medium inside the

hollow can be used effectively. A known mechanism of circulating

a heating medium can be used, but for easy-to-use, existing pumps

can be used for easy-to-use. Specific examples of the existing

pumps include centrifugal pumps, propeller pumps, viscosity

pumps of non positive displacement, reciprocating pumps, rotary

pumps of positive displacement, and jet pumps, bubble pumps,

water-hammer pumps, submersible pumps, vertical pumps for

others. For circulating a constant amount of a heating medium,

non positive-displacement pumps of a constant delivery can be

used effectively.

If the flow rate is too small, this may cause temperature

variations along the length of the electrophotographic

photoconductor. In contrasts, if the flow rate is too large, curing

may become insufficient because an increase amount of the

photoconductor surface temperature becomes small but from the

viewpoint of the volume of the space in the support, the range of

O.lL/min to 200L/min is preferably selected. As the circulation

direction of a heating medium, a backward current of the

convention flow is preferable when the convection flow rate of a

heating medium is considered.

Specifically, when a hollow photoconductor is placed

vertically so that its length is parallel to the gravity acceleration

(vertical arrangement) for exposure in view of the convenience of

the formation of a photosensitive layer and transfer of the

photoconductor, it is effective to allow a heating medium to

circulate in a direction from top to bottom of the photoconductor

from the viewpoint of its convection flow because temperature

variations along the length of the photoconductor are minimized.

A long exposure lamp is always parallel to the photoconductor,

whether vertical arrangement or horizontal arrangement.

As the heating medium, media that are thermally-stable,

have large heat capacity per unit volume, and have high thermal

conductivity are preferably used, of which media that do not

corrode apparatus, and have no irritant property are preferably.

Examples of media used as a heating medium include gas state a

heating medium such as air and nitrogen, organic a heating media

such as diphenylether, tarphenyl, and polalkyleneglycol medium,

liquid a heating media like water. An organic heating media and

water of a liquid heating medium are preferable in light of

ease-to-control of thermal conductivity and temperature, water is

particularly preferable from the viewpoint of ease-to-use.

Furthermore, to attain the evenness in the photoconductor

surface temperature and at the same time to retain temperature

increase range from the initial exposure, a method for flowing

heating medium directly inside a support, and a method for

providing an elastic member inside the support and circulating the

heating medium inside the elastic member are effective as well.

By using the elastic member, adhesiveness with a support can be

retained sufficiently, uniformity of the photoconductor surface

temperature can be reached, and the temperature increase range of

the photoconductor surface can be controlled by selecting thermal

conductivity of the elastic member.

In view of the elasticity and durability of the elastic member,

the tensile strength of the elastic member is preferably 10kg/cm ² to

400kg/cm ² , more preferably 30kg/cm ² to 300kg/cm ² . JIS-A

hardness of the elastic member is preferably 10 to 100, more

preferably 15 to 70. Moreover, from the viewpoint of temperature

increase ratio, thermal conductivity of the elastic member is

preferably O.lW/m-K to 10W/m-K, more preferably 0.2W/m"K to

5W/m-K.

The tensile strength of the elastic member and JIS-A

hardness can be measured according to "vulcanized rubber

physical testing method" of JIS K6301, "how to measure the tensile

strength of vulcanized rubber and thermoplastic rubber" of JIS

K6252, "how to measure hardness of vulcanized rubber and

thermoplastic rubber" of JIS K6253, wherein the measurements

were conducted under the environment that the temperature was

20 ⁰ G and relative humidity was 55%. The tensile strength can be

obtained by producing a specimen of dumbbell-shaped type 4,

measuring a specimen under 200mm/min of tensile speed using

TE-301 Shopper-type tensile testing device type III by TESTER

SANGYO Co., Ltd., and dividing maximum load which is the value

until the specimen was broken by the cross-section of the specimen.

JIA-A hardness is measured by producing samples of 12mm

or more of the thickness (samples of 12mm or less of the thickness

were laminated to be 12mm or more of the thickness), and using

Digital Rubber Hardness Meter Type DD2-JA by KOUBUNSHI

KEIKI Co., Ltd. Various measuring methods may be used for the

measurement of thermal conductivity, but examples include a laser

flush method, a steady heat current method, plate heat flow meter

method, heat wave method. Here, a sample which has a size of

100mmx50mmx30mm is produced and the sample can be measured

using quick thermal conductivity meter QTM- 500 by KYOTO

ELECTRONICS MANUFACTURING CO., LTD.

Examples of materials for the elastic member include rubber

materials for general use such as natural rubber, silicone rubber,

fluoro silicone rubber, ethylene propylene rubber, chloroprene

rubber, nitrile rubber, hydronitrile rubber, butyl rubber, hypalon,

acryl rubber, urethane. rubber, fluoro rubber, thermal conductivity-

sheet having high thermal conductivity, and thermal conductivity

film. Instead of the elastic member, filter material that can

adjust the amount of a heating medium of support neighborhood

inside the support can be used effectively. Specifically, generally

known filter sheets or sponge materials can be used effectively.

After application of the coating solution, a cross-linked layer

is formed by giving it external light energy and by curing. A high

pressure mercury lamp that has emission wavelength at UV

radiation mainly, an UV light source like a methal halide lamp can

be used as the light energy. Visible light sources can also be

selected depending on the type of the radically polynaerizable

ingredient and/or on the absorption wavelength of the

photopolymerizable initiator. Exposure dose is preferably

50mW/cm ² or more, more preferably 500m W/cm ² or more, most

preferably 1,000m W/cm ² or more. By using exposure light which

the irradiation light quantity is 1,000m W/cm ² or more, the

progression ratio of polymerization reaction is significantly

increased," thereby forming of a more uniform a cross-linked

surface layer becomes possible. In order to reach an even

polymerization reaction, and to form a homogeneous cross-linked

surface layer, given that irradiance where irradiance over

irradiated body is 100%, the irradiance range is at least 70% or

more, preferably 80% or more, more preferably 90% or. more. . By

doing so, the cross-linked layer of small irradiance unevenness

having uniform property can be attained.

Other external energy such as light, heat, and radiation ray

can also be used effectively. The method for adding heat energy is

to heat from the coating surface side or the support side by using

gas such as air, and nitrogen, steam, various types of heating

media, infrared radiation, and electromagnetic wave. The heat

temperature is preferably 100 ⁰ C or more, more preferably 170 ⁰ C or

less. If the heat temperature is below 100 ⁰ C, the reaction rates

slow; thereby the reaction may fail to be completed. On the other

hand, if the heat temperature is above 170 ⁰ C, the reaction may

progress unevenly and a large strain in the cross-linked layer may

occur. For an even curing reaction, a method for heating at

relative low temperature of below 100 ⁰ C and further heating with

above 100 ⁰ C to complete the reaction is also effective. Examples

of the radiation energy include the use of electron beam. Of these

energies, the use of heat and light energy are effective from

ease-to-control reaction speed, and ease-to-use of an apparatus,

and light energy is effective from ease-to-handle, and property of

obtained cross-linked surface layer.

Because the thickness of the cross-linked layer may differ

depending on the layer structure of the photoconductor using the

cross-linked layer, it is described according to the following

explanation of the layer structure.

<Layer Structure of the Electrophotographic Photoconductor>

The electrophotographic photoconductor used in the present

invention will be described with reference to the drawings.

FIG. 2A and FIG. 2B are a cross-sectional view of the

electrophotographic photoconductor of the present invention,

showing a single-layer photoconductor in which a photosensitive

layer 33 having both charge generating function and charge

transport function simultaneously is formed over the support 31.

FIG. 2A represents the case that a cross-linked layer (a

cross-linked photosensitive layer 32) is an overall photosensitive

layer. FIG. 2B represents the case that a cross-linked layer is the

surface part (a cross-linked surface layer 32) of a photosensitive

layer 33.

FIG. 3A and FIG. 3B are laminate-structured

photoconductors which are laminated by a charge generating layer

35 having charge generating function and a charge transport layer

37 having charge transport function over the support 31. FIG. 3A

shows the case that a cross-linked layer (a cross-linked charge

transport layer 32) is a total charge transport layer and FIG. 3B

shows the case that a cross-linked layer (a cross-linked surface

layer 32) is the surface part of a charge transport layer 37.

-Support-

The support is not particularly limited and can be properly

selected according to the application and may be of any having

electric conductivity of volume resistance, 10 ¹⁰ ω' cm or less.

Examples of a support include film-shaped, cylindrically-shaped

plastic or paper covered with metals such as aluminum, nickel,

chromium, nichrome, copper, gold, silver, or platinum or metal

oxides such as tin oxide or indium oxide by vapor deposition or

sputtering. Or the support may be a plate of aluminum,

aluminum alloy, nickel or stainless steel, or a plate formed into a

tube by extrusion or drawing and surface-treating by cut, finish

and polish, etc. The endless nickel belt and the endless stainless

steel belt such as those disclosed in JP-A No. 52-36016 may also be

employed as a support.

In addition to the support described above, those obtained by

dispersing conductive powers in suitable binder resin and applying

the binder resin over the support may be used as the support of the

present invention.

Examples of conductive fine particles include metal powders

such as carbon black, acetylene black, aluminum, nickel, iron,

nichrome, copper, zinc and silver, and metal oxide fine particles

such as of conductive tin oxide and ITO. Examples of

simultaneous use binder resins include thermoplastic resins,

thermosetting resins, or photocoagulating resins such as

polystyrene, styrene acrylonitrile copolymer, styrene butadiene

copolymer, styrene maleic anhydride copolymer, polyester,

polyvinyl chloride, vinyl chloride -vinyl acetate copolymer,

polyvinyl acetate, polyvinylidene chloride, polyacrylate resin,

phenoxy resin, polycarbonate, cellulose acetate resin,

ethyl-cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl

toluene, polyN-vinylcarbazole, acrylate resin, silicone resin, epoxy

resin, melamine resin, urethane resin, phenol resin, alkyd resin,

etc.

The conductive layer can be prepared by dispersing these

conductive fine particles and the binder resin into a suitable

solvent, for example, tetrahydrofuran, dichloromethane, methyl

ethyl ketone, toluene, etc and by applying this coating solution.

Furthermore, supports which are prepared by forming a

conductive layer on a suitable cylindrical base with a

thermal-contractive inner tube made of suitable materials such as

polyvinyl chloride, polypropylene, polyester, polystyrene,

polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon™*

etc. containing conductive fine particles may also be used as the

conductive support in the present invention.

<Photosensitive Layer>

The photosensitive layer may be either a laminated

structure or a singe layer structure. In case of the laminated

structure, a photosensitive layer contains a charge generating

layer and a charge transport layer having charge transport

function. In case of the single-layer, a photosensitive layer is the

layer that has charge generating function and charge transport

function simultaneously.

The following are the description for the laminated structure

photosensitive layer and the single-layer photosensitive layer.

<Photosensitive Layer in Laminated Structure>

The laminated photosensitive layer consists of a charge

generating layer and a charge transport layer.

-Charge Generating Layer-

The charge generating layer is a layer which mainly

contains a charge generating substance having charge generating

function and may also contain a binder resin or other element(s) as

necessary. The charge generating substances may be classified

into inorganic materials and organic materials and both are

suitable for use.

Examples of inorganic materials include crystalline

selenium, amorphous selenium, selenium-tellurium,

selenium-tellurium-halogen, selenium-arsenic compound, and

amorphous silicon. The amorphous silicon may have dangling

bonds terminated with hydrogen atom or a halogen atom, or it may

be doped with boron or phosphorus.

The organic material may be selected from conventional

materials, examples thereof include phthalocyanine pigments such

as metal phthalocyanine, non-metal phthalocyanine, azulenium

salt pigments, squaric acid methine pigment, azo pigments having

a carbazole skeleton, azo pigments having a triphenylamine

skeleton, azo pigments having diphenylamine skeleton, azo

pigments having dibenzothiophene skeleton, azo pigments having

fluorenone skeleton, azo pigments having oxadiazole skeleton, azo

pigments having bisstylbene skeleton, azo pigments having

distyryl oxiadiazole skeleton, azo pigments having

distyrylcarbazole skeleton, pherylene pigments, anthraquinone or

polycyclic quinone pigments, quinone imine pigments,

diphenylmethane or triphenylmethane pigments, benzoquinone or

haphtoquinone pigments, cyanine or azomethine pigments,

indigoido pigments, bisbenzimidazόle pigments. These charge

generating substances may be used alone or in combination.

Examples of binder resins which may be used in a charge

generating layer as necessary include polyamides, polyurethanes,

epoxy resins, polyketones, polycarbonates, silicone resins, acrylic

resins, polyvinyl butyrals, polyvinyl formals, polyvinyl ketones,

polystyrenes, poly-N-vinyl carbazoles, and polyacrylamides.

These binder resins may be used alone or in combination.

As a binder resin for a charge generating layer, in addition

to the binder resins listed above, polymer charge transport

materials having charge transport function can be used such as

polycarbonates having allylamine skeleton, benzydine skeleton,

hydrazone skeleton, carbazolyl skeleton, stilbene skeleton,

pyrazoline skeleton, high-polymer materials such as polyester,

polyurethane, polyether, polysiloxane, acrylic resin, high-polymer

materials having polysilane skeleton.

Specific examples of charge transport high polymer

materials are disclosed in JP-A Nos. 01-001728, 01-009964,

01-013061, 01-019049, 01-241559, 04-011627, 04-175337,

04-183719, 04-225014, 04-230767, 04-320420, 05-232727,

05-310904, 06-234836, 06-234837, 06-234838, 06-234839,

06-234840, 06-234841, 06-239049, 06-236050, 06-236051,

06-295077, 07-056374, 08-176293, 08-208820, 08-211640,

08-253568, 08-269183, 09-062019, 09-043883, 09-71642, 09-87376,

09-104746, 09-110974, 09-110976, 09-157378, 09-221544,

09-227669, 09-235367, 09-241369, 09-268226, 09-272735,

09-302084, 09-302085, 09-328539, etc.

Specific examples of high-molecular weight materials

containing polysilane skeleton are polysilylene polymers disclosed

in JP-A Nos. 63-285552, 05-19497, 05-70595 and 10-73944, etc.

Furthermore, low-molecular weight charge transport

materials can be. incorporated into charge generating layers. The

charge transport materials can be classified into hole transport

substances and electron transport substances.

Examples of an electron transport materials include

electron-accepting substances such as chloroanil, bromoanil,

tetracyanoethylene, tetracyano quinodimethane,

2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone,

2,4,5, 7 - tetranitroxanthone , 2,4, 8 -trinitrothioxanthone ,

2,6,8-trinitro-4H-indino[l,2-b]thiophene-4-on,

l,3,7-trinitro"dibenzothiophene-5,5-dioxide, and dipb.enoqui.none

derivatives. These electron transport substances may be used

alone or in combination.

Examples of hole transporting substances include oxazole

derivatives, oxadiazole derivatives, imidazole derivatives,

monoarylamines, diarylamines, triarylamines, stilbene derivatives,

orphenyl stilbene derivatives, benzidine derivatives,

diarylmethane derivatives, triarylmethane derivatives,

9-styrylanthracene derivatives, pyrazoline derivatives, divinyl

benzene derivatives, hydrazone derivatives, indene derivatives,

butadiene derivatives, pyrene derivatives, bisstylbene derivatives,

enamine derivatives. These hole transporting substances may be

used alone or in combination.

The method for forming a charge generating layer may be

broadly classified into the following two methods ^: vacuum thin-film

deposition, and casting method with solution dispersal.

The vacuum thin-film deposition includes vacuum

evaporation, glow discharge electrolysis, ion plating, sputtering,

reactive-sputtering, and CVD processes, which may form inorganic

materials or organic materials satisfactory.

In order to form a charge generating layer by the casting

method, the charge generating layer can be formed as follows: an

inorganic or organic charge generating substance is dispersed in a

solvent such as tetrahydrofuran, dioxane, dioxolane, toluene,

dichloromethane, monochlorobenzene, dichloroethane,

cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl

ketone, acetone, ethyl acetate, or butyl acetate, together with

binder resin as required, using a ball mill, ATTRITOR, sand mill,

or bead mill using. The resultant dispersion liquid is then

properly diluted and applied by coating. A leveling agent such as

dimethyl silicone oil, methylphenyl silicone oil, or the like may be

added to the dispersion liquid as required. The dispersion liquid

may be applied by way of dip coating, spray coating, bead coating,

ring coating.

The thickness of the charge generating layer is preferably

O.Olμm to 5μm, more preferably O.Oδμm to 2μm.

-Charge Transport Layer-

The charge transport layer is the layer, which has a charge

transport function and the cross-linked layer in the present

invention may be used effectively as the charge transport layer. If

the cross-linked layer is the overall charge transport layer, as

described in the cross-linked layer manufacturing method,

applying the coating solution containing radically polymerizable

composition of the present invention (charge transport compound

having the radically polymerizable compound with no charge

transport structure and a radically polymerizable functional

group ; same as follows) over the charge generating layer, after

drying as necessary, starting curing reaction by external energy,

thereby forming the cross-linked charge transport layer. The

thickness of the cross-linked charge transport layer is preferably

lOμm to 30μm, more preferably lOμm to 25μm. If the thickness is

below lOμm, a sufficient charging potential may not be maintained.

If the thickness exceeds 30μm, peeling with lower layer may be

prone to occur because of the volume constriction at the time of

curing.

If the cross-linked layer is the cross-linked surface layer

formed on the charge transport layer, the charge transport layer is

formed by dissolving or dispersing charge transport materials

having charge transport function and tying resin in a proper

solvent, coating on the charge generating layer, followed by drying.

The cross -linked surface layer is formed b3^ applying the coating

solution containing the radically polymerizable composition of the

present invention on the charge transport layer, cross-linked

curing by external energy.

As for the charge transport materials, the electron transport

substances, hole transport substances, and charge transport

polymers described above may be employed. Particularly, charge

transport polymers are preferable because solubility of the

undercoat layer may be suppressed upon coating of a cross-linked

surface layer.

Examples of the binder resin include polystyrene,

styrene-acrylonitrile copolymers, styrene-butadiene copolymers,

styrene-maleic anhydride copolymers, polyester, polyvinyl chloride,

vinylchloride-vinylacetate copolymers, polyvinyl acetate,

polyvinylidene chloride, polyacrylate resins, phenoxy resins,

polycarbonates, cellulose acetate resins, ethyl- cellulose resins,

polyvinyl butyral, polyvinyl formal, polyvinyl toluene,

poly-N-vinylcarbazole, acrylate resins, silicone resins, epoxy resins,

melamine resins, urethane resins, phenol resins, alkyd resins.

These can be used alone or in combination.

The amount of charge transport materials is preferably 20

parts by mass to 300 parts by mass, more preferably 40 parts by

mass to 150 parts by mass per 100 parts by mass of the binder

resin. When the charge transport material is a polymer, the

charge transport materials may be employed without binder resin.

The solvent used in the coating solution of the charge

transport layer may be the same as those used in the charge

generating layer described above. Preferably, the solvent can

dissolve well in both of charge transport materials and the binder

resin. The solvent can be used alone or in combination. The

same method as used for the charge generating layer may be

applied for charge transport layer formation.

The plasticizer and the leveling agent may be added

depending on the requirements. Specific examples of plasticizers

used concomitantly with the charge transport layer include known

ones that are being used for plasticizing resins such as dibutyl

phthalate, dioctyl phthalate. The added amount of plasticizer is 0

part by mass to 30 parts by mass per 100 parts by mass of binder

resin.

Specific examples of leveling agents used concomitantly with

the charge transport layer include silicone oils such as dimethyl

silicone oil, and methyl phenyl silicone oil; polymers or oligomers

including a perfluoroalkyl group in their side chain. The added

amount of leveling agents is 0 part by mass to 1 part by mass per

100 parts by mass of binder resin.

The thickness of the charge transport layer is preferably

5μm to 40μm, more preferably lOμm to 30μm.

As described in the surface layer producing method, the

cross-linked surface layer is formed by applying the coating

solution containing the radically polymerizable composition of the

present invention on the charge transport layer, drying as

necessary, followed by starting curing reaction by heat or light

external energy.

The thickness of a cross-linked surface layer is preferably

lμm to 20μm, more preferably 2μm to lOμm. If the thickness is

below lμm, durability may vary due to uneven thickness and when

the thickness is more than 20μm, the charge transport layer

become thick and cause image reproducibility degradation due to a

charge diffusion.

<Single -Layer Photosensitive layer>

The single-layer structural a cross-linked photosensitive

layer is the layer that has charge generating function and charge

transport function simultaneously. By containing charge

generating substances having charge generating function, the

cross-linked photosensitive layer having charge transport

structure of the present invention is effectively used as a

single-layer cross-linked photosensitive layer. As described in the

casting forming method for the charge generating layer, the

cross-linked photosensitive layer is formed by dispersing charge

generating substances with the coating solution containing

radically polymerizable composition, drying as necessary, followed

by starting curing reaction by external energy. Either the charge

generating substance or dispersed liquid containing the charge

generating substance with solvent may be added to the coating

solution for the cross-linked photosensitive layer.

The thickness of the cross-linked photosensitive layer is

preferably lOμm to 30μm, more preferably lOμm to 25μm. If the

thickness is below lOμm, sufficient charging potential may not be

maintained. If the thickness exceeds 30μm, separation from an

electrically conductive support undercoat layer may be prone to

occur because of volume constriction at the time of curing.

When the cross-linked surface layer is formed over the

surface of single-layer photosensitive layer, the photosensitive

layer is formed by dissolving or dispersing a charge generating

substance, charge transport materials, and a binder resin in a

proper solvent and applying the resulting coating solution,

followed by drying. A plasticizer, a leveling agent, or the like may

also be added as needed. The dispersion method for charge

generating substances, charge transport materials, plasticizers,

and leveling agents may be the same as those which are used for

the charge generating layers and charge transport layers. As for

the binder resin, in addition to the binder resins described for the

charge transport layer, the binder resins described for the charge

generating layers may be employed in combination. Besides, the

charge transport polymer may be used, which is favorable in

reducing the inclusion of photosensitive composition of a lower

layer into the cross-linked surface layer.

The thickness of the photosensitive layer is preferably 5μm

to 30μm, more preferably lOμm to 25μm.

The cross-linked surface layer is formed over the surface of a

singlβ"layer photosensitive layer, a coating solution containing

radically polymerizable composition and a charge generating

substance is applied on the upper layer of the photosensitive layer,

followed by drying as needed, and curing by the use of external

energy ^: heat or optical energy.

Preferably, the cross-linked surface layer has a thickness of

lμm to 20μm, more preferably 2μm to lOμm. If the thickness is

below lμm, durability may fluctuate due to uneven thickness.

The charge generating substance contained in the

single-layer photosensitive layers is preferably 1% by mass to 30%

by mass. The binder resin contained in the photosensitive layer is

preferably 20% by mass to 80% by mass based on the total amount

of the photosensitive layer. The charge transport materials

contained in the photosensitive layer is preferably 10% by mass to

70% by mass.

For the electrophotographic photoconductor of the present

invention, in case of forming the cross-linked surface layer on the

photosensitive layer, providing the intermediate layer is possible

for the purpose of flower layer ingredient from mixing with the

cross-linked surface layer or of improving adhesiveness with the

lower layer. This intermediate layer is produced by the mixture of

the lower part of the photosensitive layer composition in the

cross-linked surface layer containing radically polymerizable

composition, which prevents inhibition of a curing reaction and

unevenness of the cross-linked surface layer. It is also possible to

improve adhesiveness between lower layer of the photosensitive

layer and the surface cross-linked layer.

The intermediate layer generally uses binder resin as the

major component. Examples of these resins include polyamide,

alcohol- soluble nylon, water-soluble polyvinyl butyral, polyvinyl

butyral, and polyvinyl alcohol. As forming method for the

intermediate layer, a coating method in general use is adopted as

described the above. The thickness of the intermediate layer is

preferably 0.05μm to 2μm.

In the photoconductor of the present invention, an undercoat

layer may be formed between the support and the photosensitive

layer.

The undercoat layer is typically formed of resin. The resin

is preferably highly resistant against general organic solvents

since photosensitive layers are usually applied on the undercoat

layers using organic solvent. Examples of resins include

water-soluble resins such as polyvinyl alcohol, casein and sodium

polyacrylate, alcohol- soluble resins such as copolymer nylon and

methoxymethylated nylon, and curing resins which form

three-dimensional networks such as polyurethane, melamine

resins, phenol resins, alkyd-melamine resins, and epoxy resins.

Metal oxide fine powder pigments such as titanium oxide, silica,

alumina, zirconium oxide, tin oxide or indium oxide may be added

to the undercoat layer for preventing moire patterns and reducing

residual potential.

These undercoat layers may be formed by using suitable

solvents and coating methods as the photosensitive layer. Silane

coupling agents, titanium coupling agents or chromium coupling

agents, etc. can be used as undercoat layer of the present invention.

AI2O3 prepared by anodic oxidation, organic materials such as

polyparaxylylene (parylene) and inorganic materials such as Siθ2,

Snθ2, Tiθ2, ITO, Ceθ2 prepared by vacuum thin-film forming step,

may also be used for the undercoat layer.

The thickness of the undercoat layer is preferably Oμm to

5μm.

For the photoconductor of the present invention, the

antioxidant may be added to each of the cross-linked surface layer,

the photosensitive layer, the protective layer, the charge transport

layer, the charge generating layer, the undercoat layer, and the

intermediate layer, etc. in order to improve environment resistance,

particularly to prevent sensitivity decrease and residual potential

increase.

Examples of the anti-oxidant include phenolic compounds,

p-phenylenediamine compounds, hydroquinone compounds,

organic sulfur compounds, organic phosphorus compounds. These

anti-oxidants may be used alone or in combination.

Examples of the phenolic compounds include

2,6-di-t-butyl-p-cresol, butylated hydroxyanisole,

2,6-di-t-butyl-4-ethylpenol,

stearyl-β-(3,5"di-t-butyl-4-hydroxyphenyl)propionate,

2,2'-methylene-bis-(4-methyl-6-t-butylphenol),

2,2'-methylene-bis-(4-ethyl-6-t-butylphenol),

4,4'-thiobis-(3-methyl-6-t-butylphenol),

4,4'-butylidenebis-(3-methyl-6-t-butylphenol),

l,l,3,-tris-(2-methyl-4-hydroxy-5-t-butylphneyl)butane,

l,3,5-trimethyl-2,4,6-tris)(3,5-di-t-butyl-4-hydroxybenzy l)benzene,

tetrakis"[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)

propionate]methane,

bis[3,3'-bis(4'-hydroxy-3'-t-butylphenyl)butylic acid]glycol ester

and tocopherols.

Examples of the p-phenylenediamine compounds include

N-phenyl-N'-isopropyl-p-phenylenediamine,

N,N'-di-sec-butyl-p-phenylenediamine,

N-phenyl-N-sec-butyl-p-phenylenediamine,

N,N'-di-isopropyl-p-phenylenediamine, and

N,N'-dimethyl-N,N'-di-t-butyl-p-phenylenediamine.

Examples of the hydroquinone compounds include

2,5-di-t-octylhydoquinone, 2,6-didodecylhydroquinone, 2-dodecyl

hydroquinone, 2-dodeeyl-5-chlorohydroquinone,

2-t-oetyl-5-m.ethylhydroquinone, and

2-(2-octadecenyl)-5-methylhydroquinone.

Examples of the organic sulfur compound include

dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate and

ditetradecyl-3,3'-thiodipropionate.

Examples of the organic phosphorus compounds include

triphenylphosphine, tri (nonylphenyl) phosphine, tri

(dinonylphenyl) phosphine, tricresylphosphine and tri

(2,4-dibutylphenoxy) phosphine.

These compounds are known as antioxidants for rubbers,

plastics, oils and fats, etc., and are easily commercially available.

The amount of the anti-oxidant is preferably 0.01% by mass

to 10% by mass, based on the total mass of the layer which includes

the anti-oxidant.

The added amount of the antioxidant is not limited and be

properly selected according to the application, and out of total

amount of adding layer, 0.01% by mass to 10% by mass is

preferable.

(Image Forming Method and Image Forming Apparatus)

The image forming apparatus of the present invention

includes at least a latent electrostatic image forming unit, a

developing unit, a transferring unit, a fixing unit, includes a

cleaning unit preferably, and further includes other units suitably

selected in accordance with the necessity such as a cleaning unit, a

charge elimination unit, a recycling unit, and a controlling unit.

The image forming method for the present invention includes at

least a latent electrostatic image forming unit, a developing unit, a

transferring unit, and a fixing unit and further includes other

units suitably selected in accordance with the necessity such as a

cleaning unit, a charge elimination unit, a recycling unit, and a

controlling unit.

The image forming method for the present invention can be

preferably carried out by means of the image forming apparatus of

the present invention, the formation of a latent electrostatic image

can be carried out by means of the latent electrostatic image

forming unit, the developing can be carried out by means of the

developing unit, the transferring can be carried out by means of

the transferring unit, the fixing can be carried out by means of the

fixing unit, and the other units can be carried out by means of the

other units.

The image forming method and the image forming apparatus

according to the present invention are an image forming method

and an image forming apparatus using an electrophotographic

photoconductor having a cross-linked layer includes units of

charging the photoconductor, exposing the image, developing,

transferring a toner image to an image carrier (transferring paper),

fixing and cleaning the surface of the photoconductor.

An image forming method which an electrostatic latent

image is directly transferred to a transferring medium does not

always the steps.

-Latent Electrostatic Image Forming Unit and Latent Electrostatic

Image Forming Unit-

The latent electrostatic image forming unit is a unit in

which a latent electrostatic image is formed on an

electrophotographic photoconductor.

Materials, shape, structure, and size of the

electrophotographic photoconductor are not limited, and properly

selected from known products, but drum shape can be a good use.

For the electrophotographic photoconductor, the

electrophotographic photoconductor of the present invention can be

used.

The latent electrostatic image can be formed, for example,

by charging the surface of the electrophotographic photoconductor

uniformly and then exposing the surface thereof imagewisely by

means of the latent electrostatic image forming unit. The latent

electrostatic image forming unit is provided with, for example, at

least a charger configured to uniformly charge the surface of the

electrophotographic photoconductor, and an exposure configured to

expose the surface of the electrophotographic photoconductor

imagewisely.

The surface of the electrophotographic photoconductor can

be charged by applying a voltage to the surface of the

electrophotographic photoconductor through the use of, for

example, the charger.

The charger is not particularly limited, may be suitably

selected in accordance with the intended use, and examples thereof

include contact chargers known in the art, for example, which are

equipped with a conductive or semi-conductive roller, a brush, a

film, a rubber blade or the like, and non-contact chargers utilizing

corona discharge such as corotron and scorotron.

The surface of the electrophotographic photoconductor can

be exposed, for example, by exposing the surface of the

electrophotographic photoconductor imagewisely using the

exposing apparatus.

The exposing apparatus is not particularly limited, provided

that the surface of the electrophotographic photoconductor which

has been charged by the charger can be exposed imagewisely, may

be suitably selected in accordance with the intended use, and

examples thereof include various types of the exposing apparatus

such as reproducing optical systems, rod lens array systems, laser

optical systems, and liquid crystal shutter optical systems.

In the present invention, the back light method may be

employed in which exposing is performed imagewisely from the

back side of the electrophotographic photoconductor.

When image forming apparatus is used as a copier or a

printer, image exposure is done by irradiating specula light or

transmitted light to the photoconductor from documents or by

irradiation lights to the photoconductor by laser beam scan, LED

alley drive or liquid crystal shutter alley drive according to the

signals converted by reading documents with sensors.

-Developing and Developing Unit-

The developing unit is a unit in which the latent

electrostatic image is developed using a toner or a developer to

form a visible image.

The visible image can be formed by developing the latent

electrostatic image using, for example, a toner or a developer by

means of the developing unit.

The developing unit is not particularly limited and may be

suitably selected from those known in the art, as long as a latent

electrostatic image can be developed using a toner or a developer.

Preferred examples thereof include the one having at least an

image developing device which houses a toner or a developer

therein and enables supplying the toner or the developer to the

latent electrostatic image in a contact or a non-contact state.

The image developing device normally employs a

dry-developing process. It may be a monochrome color image

developing device or a multi-color image developing device.

Preferred examples thereof include the one having a stirrer by

which the toner or the developer is frictionally stirred to be

charged, and a rotatable magnet roller.

In the image developing device, for example, a toner and the

carrier are mixed and stirred, the toner is charged by frictional

force at that time to be held in a state where the toner is standing

over the surface of the rotating magnet roller to thereby form a

magnetic brush. Since the magnet roller is located near the

electrophotographic photoconductor, a part of the toner

constituting the magnetic brush formed over the surface of the

magnet roller moves to the surface of the electrophotographic

photoconductor by electric attraction force. As a result, the latent

electrostatic image is developed using the toner to form a visible

toner image over the surface of the electrophotographic

photoconductor.

The developer to be housed in the image developing device is

a developer containing a toner, and the developer may be a one

component developer or may be a two-component developer.

Commercially available products can be used for the toner.

-Transferring and Transferring Unit-

In the transferring unit, the visible image is transferred

onto a recording medium, and it is preferably an embodiment in

which an intermediate transfer member is used, the visible image

is primarily transferred to the intermediate transfer member and

then the visible image is secondarily transferred onto the recording

medium. An embodiment of the transferring unit is more

preferable in which two or more color toners are used, an

embodiment of the transferring is still more preferably in which a

full-color toner is used, and the embodiment includes a primary

transferring in which the visible image is transferred to an

intermediate transfer member to form a composite transfer image

thereon, and a secondary transferring in which the composite

transfer image is transferred onto a recording medium.

The transferring can be performed, for example, by charging

a visible image formed over the surface of the electrophotographic

photoconductor using a transfer-charger to transfer the visible

image, and this is enabled by means of the transferring unit. For

the transferring unit, it is preferably an embodiment which

includes a primary transferring unit configured to transfer the

visible image to an intermediate transfer member to form a

composite transfer image, and a secondary transferring unit

configured to transfer the composite transfer image onto a

recording medium.

The intermediate transfer member is not particularly

limited, may be suitably selected from among those known in the

art in accordance with the intended use, and preferred examples

thereof include transferring belts.

The transferring unit (the primary transferring unit and the

secondary transferring unit) preferably includes at least an

image -transfer device configured to exfoliate and charge the visible

image formed on the electrophotographic photoconductor to

transfer the visible image onto the recording medium. For the

transferring unit, there may be one transferring unit or two or

more transferring units.

Examples of the image transfer device include corona image

transfer devices using corona discharge, transferring belts,

transfer rollers, pressure transfer rollers, and adhesion image

transfer units.

The recording medium is typically standard paper. As long

as it is transferable of unfixed image after the development, it is

not limited, and properly selected according to the application, and

PET base for OHP can also be used.

^■ Fixing and Fixing Unit-

The fixing unit is a unit in which a visible image which has

been transferred onto a recording medium is fixed using a fixing

apparatus, and the image fixing may be performed every time each

color toner is transferred onto the recording medium or at a time so

that each of individual color toners are superimposed at the same

time.

The fixing unit is not particularly limited, may be suitably

selected in accordance with the intended use, and heat-pressurizing

units known in the art are preferably used. Examples of the

heat-pressurizing units include a combination of a heat roller and a

pressurizing roller, and a combination of a heat roller, a pressurizing

roller, and an endless belt.

The heating temperature in the heat-pressurizing unit is

preferably 80°C to 200 ⁰ C.

In the present invention, for example, an optical fixing

apparatus known in the art may be used in the fixing unit and the

fixing unit, or instead of the fixing unit.

^■ Cleaning and Cleaning Unit-

The cleaning step is a step in which the electrophotographic

photoconductor is cleaned using a cleaning unit.

Examples of the cleaning unit include cleaning blades,

magnetic brush cleaners, electrostatic brush cleaners, magnetic

roller cleaners, blade cleaners, brush cleaners, web cleaners, .

The charge elimination step is a step in which charge is

eliminated by applying a charge -eliminating bias to the

electrophotographic photoconductor, and it can be suitably

performed by means of a charge -eliminating unit.

The charge-eliminating unit is not particularly limited as

long as a charge-eliminating bias can be applied to the

electrophotographic photoconductor, and may be suitably selected

from among charge -eliminating units known in the art. For

example, a charge-eliminating lamp or the like is preferably used.

The recycling unit is a unit in which the electrophotographic

toner that had been eliminated in the cleaning is recycled in the

developing, and the recycling can be suitably performed by means

of a recycling unit.

The recycling unit is not particularly limited, and examples

thereof include carrying units known in the art.

The controlling unit is a unit in which each of the steps are

controlled, and the each of these steps can be preferably controlled

by using a controlling unit.

The controlling unit is not particularly limited and may be

suitably selected in accordance with the intended use as long as

operations of each of the units can be controlled, and examples

thereof include equipment such as sequencers and computers.

Next, the image forming method and the image forming

apparatus according to the present invention will be described in

detail with reference to the drawings.

FIG. 4 is a schematic view showing an example of the image

forming apparatus. As a charging unit for charging the

photoconductor uniformly, the charging charger 3 is used.

Examples of the charging unit include a conventional unit, such as

a corotron device, a scorotron device, a solid discharging element, a

needle electrode device, a roller charging device and an

electrically-conductive brush device.

The configuration of the present invention is particularly

effective if a charging unit that the photoconductor composition is

dissolved by proximity discharging from charging unit such as

contact charging system or non-contact proximity placement

charging system is used. The term "the contact charging system"

means the charging system in which a charged roller, a charged

brush, a charged blade, directly touches the photoconductor. On

the other hand, proximity charging system is the one that the

charged roller is proximity placed with non-contact state having .

air gap of 200μm or less between the photoconductor surface and

the charging unit for instance. If this air gap is too large,

charging tends to be unstable, whereas if this air gap is too small,

in case that the residual toner exist the photoconductor, a charging

member surface may be contaminated. Consequently, the air gap

is preferably lOμm to 200μm, more preferably lOμm to lOOμm.

Next, for forming an electrostatic latent image in the

photoconductor 1 charged uniformly, the image exposing unit 5 is

used. Examples of the light source of the image exposing unit 5

include a general illuminant, such as a fluorescent light, a

tungsten lamp, a halogen lamp, a mercury vapor lamp, a sodium

lamp, a light emitting diode (LED), a laser diode (LD) and an

electro luminescence (EL). For exposing a light having only a

desired wavelength, various filters, such as a sharp cut filter, a

band pass filter, a near-infrared cutting filter, a dichroic filter, an

interference filter and a color conversion filter can be used.

Next, for visualizing an electrostatic latent image formed on

the photoconductor 1, the developing unit 6 is used. Examples of

the developing method include a one-component developing and a

two-component developing using a dry toner and a wet developing

using a wet toner. By charging the photoconductor 1 positively

(negatively) and by exposing the image in the photoconductor 1, a

positive (negative) electrostatic latent image is formed on the

surface of the photoconductor 1. Further, by developing the

formed latent image with a negative (positive) toner

(voltage-detecting fine particles), a positive image can be obtained

and by developing the formed latent image with a positive

(negative) toner, a negative image can be obtained.

Next, for transferring the visualized toner image in the

photoconductor 1 to the transferring medium 9, the transferring

charger 10 is used. For transferring the toner image more

advantageously, the transferring pre-charger 7 may be also used.

Examples of the transferring method include an electrostatic

transferring method using a transferring charger and a bias roller?

a mechanical transferring method, such as an adhesion

transferring method and a pressing transferring method? and a

magnetic transferring method. The electrostatic transferring

method can use the charging unit.

Next, as an unit for peeling the transferring medium 9 from

the photoconductor 1, the peeling charger 11 and the peeling claw

12 can be used. Examples of the other peeling unit include an

electrostatic adsorption inducing peeling unit, a side belt peeling

unit, a top grip conveying unit and a curvature peeling unit. As

the peeling charger 11, the charging unit can be used.

Next, for cleaning a residual toner on the photoconductor 1

after the transferring, the fur brush 14 and the cleaning blade 15

are used. For cleaning the residual toner more effectively, the

cleaning pre-charger 13 may be also used. Examples of the other

cleaning unit include a web cleaning unit and a magnetic brush

cleaning unit. These cleaning units may be used individually or

in combination.

Next, optionally for removing the latent image formed in the

photoconductor 1, a neutralizing unit is used. Examples of the

neutralizing unit include the neutralizing lamp 2 and a

neutralizing charger. As the neutralizing lamp 2 and the

neutralizing charger respectively, the exposing light source and

charging unit respectively can be used.

As other units, such as a document reading unit, a paper

feeding unit, a fixing unit and a paper discharging unit, which are

arranged distantly from the photoconductor 1, conventional units

may be used.

The present invention is an image forming method and

image forming apparatus using the photoconductor for the

electrophotography of the present invention as the image forming

unit.

The image forming unit may be either fixed and

incorporated in a copying machine, a facsimile machine or a

printer,' or detachably incorporated as a process cartridge

described in the following.

(Process Cartridge)

The process cartridge of the present invention including the

electrophotographic photoconductor of the present invention and

any one of at least-

a charging unit configured to charge the surface of the

electrophotographic photoconductor, an exposing unit configured to

expose the surface of the exposed photoconductor to form latent

electrostatic image, a developing unit configured to develop latent

electrostatic image formed on the electrophotographic

photoconductor using toner to form visible image, a transferring

unit, a cleaning unit, and a charge elimination unit.

An example of the process cartridge is shown in FIG. 5.

The process cartridge includes the photoconductor 101 and at least

one of the charging unit 102, the developing unit 104, the

transferring unit 106, the cleaning unit 107 and a neutralizing unit

(not disclosed in FIG. 5), and the process cartridge is detachably

attached in the main body of the image forming apparatus.

The image forming step using the process cartridge shown in

FIG. 5 includes rotating the photoconductor 101 in the direction

shown by the arrow; charging the photoconductor 101 using the

charging unit 102," exposing the photoconductor 101 using the

exposing unit 103; thereby forming an electrostatic latent. image

corresponding to the exposed image in the surface of the

photoconductor 101; toner-developing the electrostatic latent

image using the developing unit 104; transferring the developed

toner image to the transferring medium 105 using the transferring

unit 106, thereby printing out the image; cleaning the surface of

the photoconductor 101 after the image transferring using the

cleaning unit 107; and neutralizing the photoconductor 101 using a

neutralizing unit (not disclosed in FIG. 5), wherein during the

process, the photoconductor 101 is rotated. This process is

repeated.

As is clear from explanations given above, the

photoconductor for the electrophotography according to the present

invention can be widely applied not only to copying apparatuses for

the electrophotography, but also to electrophotography application

fields, such as laser beam printers, CRT printers, LED printers,

liquid crystal printers and laser plate makings.

Examples

Herein below, with referring to Examples and Comparative

Examples, the present invention is explained in detail and the

following Examples and Comparative Examples should not be

construed as limiting the scope of this invention. All parts are

expressed by mass unless indicated otherwise.

(Example l)

An undercoat layer of 3.5μm in thickness, a charge

generating layer of 0.2μm in thickness, and the charge transport

layer of 23μm in thickness were formed on aluminum cylinder of

30mm in diameter by sequentially applying the coating solution for

undercoat layer of the following, applying the coating solution for

the charge generating layer of the following, applying the coating

solution for the charge transport layer of the following, and

followed by drying.

Then, the surface cross-linked layer of 7μm in thickness was

provided by spraycoating coating solution for a cross-linked

surface layer of the following on the charge transport layer,

exposing under the condition of 150sec exposing time by using UV

lamp system by Fusion shown in FIG. 6A and UV lamp system by

USHIO shown in FIG. 6B, and followed by drying for 20min at

130 ⁰ C. Hereinbefore, the electrophotographic photoconductor of

Example 1 was produced.

Here, FIG. 6A shows a (vertical radiation) UV lamp system

by Fusion, 51 in FIG. 6A denotes a vertically placed photoconductor,

52 is a lamp, and arrows in FIG represent irradiation light. FIG.

6B shows a (horizontal radiation) UV lamp system manufactured

by USHIO, 51 in FIG.6A denotes a horizontally placed

photoconductor, 52 is a lamp, and arrows in FIG represent

irradiation light.

[Composition of Coating solution for Undercoat Layer]

^• Alkyd resin ^{• • •} 6 parts

(Beckosol 1307-60-EL by Dainippon Ink and Chemicals, Inc.)

• Melamine resin • ^{• •} 4 parts

(Super Beckamine G-821-60 by Dainippon Ink and Chemicals,

Inc.)

^• Titanium oxide ^{• • •} 40 parts

• Methyl ethyl ketone ^{• • •} 50 parts

[Composition of Coating Solution for Charge Generating Layer]

• Titanylphthalocyanin • • • 2.5 parts

• Polyvinylbutyral (XYHL by UCC Inc.) • • • 0.5 parts

• Cyclohexanone • • • 200 parts

• Methyl ethyl ketone • • • 80 parts

[Composition of Coating solution for Charge Transport Layer]

^• Bisphenol z-type polycarbonate * • • 10 parts

(Panlight TS-2050 by TEIJIN CHEMICALS LTD.)

• Low-molecule charge transport material expressed by the

following Structural Formula (II) • • • 7 parts

Structural Formula (II)

• Tetrahydrofuran • • • 100 parts

^• Tetrahydrofuran solution of 1% by mass of silicone oil ^{• • •} 0.2

parts

(KF50-100CS by Shinetsu Chemical Co., Ltd.)

[Composition of Coating Solution for a Cross-Linked Surface

Layer]

• A radically polymerizable compound with charge transport

structure • • • 10 parts

Example compound No.54 (molecular weight : 419, number of

functional group • ^" l)

^• Radically polymerizable monomer with no charge transport

structure ^{• •} • 10 parts

Trimethylol propane triacrylate (KAYARAD TMPTA by

Nippon Kayaku Co., Ltd., molecular weight • 296, number of

functional groups ^' ■ 3)

^• Photopolymerizable initiator • • • 1 part

IRGACURABLE 184 (by Nippon Kayaku Co., Ltd., molecular

weight : 204)

• Solvent

Tetrahydrofuran ^{• • •} 90 parts

(boiling point : 66°C, saturated vapor pressure •

176mmHg/25°C)

Butyl acetate (boiling point • 126°C, saturated vapor

pressure : 13mmHg/25°C) • • • 30 parts

[Exposure Condition and Method for Controlling Temperature]

^• Fusion (vertical radiation) UV lamp system

(light intensity ■ ^' 3300W/cm ² )

^• Irradiation chamber atmosphere '• air

^• Heating medium : water (flow rate : 3.5L/min, circulation

direction • top to bottom of the photoconductor)

^• Elastic member : NA

(Example 2)

An electrophotographic photoconductor of Example 2 was

produced similar to that in that in Example 1 except for altering

the composition to the following of the coating solution for a

cross-linked surface layer, exposure condition, and the method for

controlling temperature for Example 1.

[Coating Solution for a Cross-Linked Surface Layer]

• A radically polymerizable compound with charge transport

structure ^{• • •} 10 parts

Example compound No.180 (molecular weight : 591, number

of functional groups : 2)

• Radically polymerizable monomer with no charge transport

structure ^{• • •} 10 parts

Dipentaerythrytolhexalcrylate (by Nippon Kayaku Co., Ltd.,

KAYARAD DPHA, average molecular weight : 536, number of

functional groups • ^' 5.5)

• Photopolymerizable initiator • • • 1 part

IRGACURE 2959 (by Nippon Kayaku Co., Ltd., molecular

weight : 224)

^• Solvent

Tetrahydrofuran ^{• • •} 60 parts

(boiling point : 66°C, saturated vapor pressure :

176mmHg/25°C)

Cyclohexanone • • • 60 parts

(boiling point • 156 ⁰ C, saturated vapor pressure '

3.95mmHg/25°C)

[Exposure Condition and Method for Controlling Temperature]

• UV lamp system by Fusion (light intensity : 2700W/cm ² )

• Irradiation chamber atmosphere • air

• Heating medium • water (flow rate • 3.5L/min, circulation

direction • top to bottom of the photoconductor)

• Elastic member : natural rubber sheet of 3mm thickness

(tensile strength '■ 300kg/cm ² , JIS-A hardness - 50, thermal

conductivity : 0.13W/m-K)

(Example 3)

The electrophotographic photoconductor of Example 3 was

produced similar to that in Example 1 except for altering the

composition to the following of the coating solution for a

cross-linked surface layer, exposure condition, and the method -for

controlling temperature

[Coating Solution for a Cross-Linked Surface Layer]

• A radically polymerizable compound with charge transport

structure • • • 10 parts

Example compound No.105 (molecular weight : 445, number

of functional groups ■ l)

• Radically polymerizable monomer with no charge transport

structure

Dipentaerythrytolhexyacrylate (by Nippon Kayaku Co., Ltd.,

K-AYARAD DPHA, average molecular weight : 536, number of

functional group '■ 5.5) • • • 5 parts

Trimethylol propane trimethacrylate (by Kayaku Sartomer,

SR-350, average molecular weight : 338, number of functional

groups - 3) ^• • ^• 5 parts

• Photopolymerizable initiators • • • 1 part

KAYACURE CTX (by Nippon Kayaku Co., Ltd., molecular

weight •" 204)

• Solvent • • • 120 parts

Tetrahydrofuran (boiling point •" 66°C, saturated vapor

pressure : 176mmHg/25°C)

[Exposure Condition and Method for Controlling Temperature]

• UV lamp system by Fusion (light intensity : 1300W/cm ² )

• Irradiation chamber atmosphere :_ air

• Heating medium : BARRELSAM 200 (by Matsumura Oil,

organic a heating medium oil)

^• Flow rate •" 3.5L/min, circulation direction - top to bottom of

the photoconductor)

• Elastic member ■ silicone rubber sheet of 3mm thickness

(tensile strength : 45kg/cm ² , JIS-A hardness : 48, thermal

conductivity : 0.35W/m-K)

(Example 4)

The electrophotographic photoconductor was produced

similar to that in Example 1 except for altering the composition to

the following of the coating solution for a cross-linked surface layer,

exposure condition, and the method for controlling temperature for

Example 1.

[Coating Solution for a Cross-Linked Surface Layer]

• A radically polymerizable compound with charge transport

structure • • • 10 parts

Example compound No.173 (molecular weight : 628, number

of functional groups : 2)

• Radically polymerizable monomer with no charge transport

structure

Caprolactone-modified-dipentaerythrytol hexaacrylate (by

Nippon Kayaku Co., Ltd., KAYARAD DPCA- 120, average molecular

weight • 1948, number of functional groups : 6) • • • 5 parts

Pentaerythrytoltetracrylate (by KAYAKU Sartomer, SR-295,

average molecular weight - 3528, number of functional groups •

4) • • • 5 parts

^• Photopolymerizable initiator ^{• • •} 1 part

IRGACURE 819 (by Nippon Kayaku Co., Ltd., molecular

weight : 204)

^• Solvent

Tetrahydrofuran (boiling point : 66 ⁰ C, saturated vapor

pressure : 176mmHg/25°C) • ^• • 60 parts

2-propanol (boiling point • 82°C, saturated vapor pressure •

32.4mmHg/25°C) ^{• • •} 60 parts

[Exposure Condition and Method for Controlling Temperature]

^• UV lamp system by Fusion (light intensity : lOOOW/cm ² )

^• Irradiation chamber atmosphere ^' air

^• Heating medium : BARRELSAM 200 (by Matsumura Oil,

organic a heating medium oil, flow rate ^: 3.5L/min, circulation

direction • top to bottom of the photoconductor)

• Elastic member • urethane sponge of 5 mm in thickness

(tensile strength • 0.05kg/cm ² , JIS-A hardness ^' 12, thermal

conductivity : 0.043W/m-K)

(Example 5)

The electrophotographic photoconductor was produced

similar to that in Example 1 except for altering the composition to

the following of the coating solution for a cross-linked surface layer,

exposure condition, and the method for controlling temperature.

[Coating Solution for a Cross-Linked Surface Layer]

- A radically polymerizable compound with charge transport

structure ^{■ • •} 10 parts

Example compound No.135 (molecular weight : 581, number

of functional groups ^' ■ l)

• Radically polymerizable monomer with no charge transport

structure

Caprolactone-modified-dipentaerythrytol hexaacrylate (by

Nippon Kayaku Co., Ltd., KAYARAD DPCA- 120, average molecular

weight : 1948, number of functional groups ^' 6) ^{• • •} 5 parts

Trimethylol propane triacrylate (by Nippon Kayaku Co., Ltd.,

KAYARAD TMPTA, molecular weight : 296, number of functional

groups ^: 3) ^{• •} • 5 parts

• Photopolymerizable initiator ^• • • 1 part

KAYACURE DETX-S (by Nippon Kayaku Co., Ltd., molecular

weight : 268)

^• Solvent • • • 120 parts

Tetrahydrofuran (boiling point • 66°C, saturated vapor

pressure : 176mmHg/25°C)

[Exposure Condition and Method for Controlling Temperature]

• UV lamp system by Fusion (light intensity : 3300W/cm ² )

• Irradiation chamber atmosphere • air

• Heating medium • water (flow rate : 3.5L/min, circulation

direction ^' ■ from top to bottom of the photoconductor)

• Elastic member • radiating silicone rubber sheet of lmm of

the thickness (by Shin-Etsu Chemical Co. Ltd., thermal

conductivity ■ 5.0W/m-K, tensile strength • 20kg/cm ² , JIS-A

hardness : 23)

(Example 6)

The electrophotographic photoconductor of the Example 6

was produced similar to that in the Example 1 except for altering

the composition to the following of the coating solution for a

cross-linked surface layer, exposure condition, and method for

controlling temperature.

[Coating Solution for a Cross-Linked Surface Layer]

^• A radically polymerizable compound with charge transport

structure • • • 10 parts

Example compound No.54 (molecular weight : 419, number of

functional groups • l)

^• Radically polymerizable monomer with no charge transport

structure ^• • ^• 10 parts

Trimethylol propane triacrylate (by Nippon Kayaku Co., Ltd.,

KAYARAD TMPTA, molecular weight : 296, number of functional

groups : 3)

• Photopolymerizable initiator ^{• • •} 1 part

IRGACURE 184 (by Nippon Kayaku Co., Ltd., molecular

weight : 204)

^• Solvent

Tetrahydrofuran (boiling point : 66 ⁰ C, saturated vapor

pressure : 176mmHg/25°C) • • ^• 90 parts

Butyl acetate (boiling point : 126°C, saturated vapor

pressure : 13mmHg/25°C) • • • 30 parts

[Exposure Condition and Method for Controlling Temperature]

• By USHIO (horizontal radiation) UV lamp system (light

intensity : 800W/cm ² )

• Irradiation chamber atmosphere : air

• Heating medium • water (flow rate : 3.5L/min, circulation

direction - left to right of the photoconductor)

• Elastic member '■ NA

(Example 7)

The electrophotographic photoconductor of Example 7 was

produced similar to that in the Example 1 except for altering the

composition to the following of the coating solution for a

cross-linked surface layer, exposure condition, and the method for

controlling temperature.

[Coating solution for a cross-linked surface layer]

• A radically polymerizable compound with charge transport

structure — 10 parts

Example compound No.54 (molecular weight : 419, number of

functional groups • 1)

^• Radically polymerizable monomer with no charge transport

structure • • • 10 parts

Trimethylol propane triacrylate

(by Nippon Kayaku Co., Ltd., KAYAEAD TMPTA, molecular

weight : 296, number of functional groups : 3)

^• Photopolymerizable initiator ^• • ^• 1 part

IRGACURE 184 (by Nippon Kayaku Co., Ltd., molecular

weight : 204)

• Solvent

Tetrahydrofuran • • • 90 parts

(boiling point : 66°C, saturated vapor pressure :

176mmHg/25°C)

Butyl acetate (boiling point • 126°C, saturated vapor

pressure : 13mmHg/25°C) • • * 30 parts

[Exposure Condition and Method for Controlling Temperature]

• UV lamp system by Fusion (light intensity • 3300W/cm ² )

^• Irradiation chamber atmosphere • nitrogen substituted

(oxygen concentration • 1% or less)

• Heating medium '■ water (flow rate : 3.5L/min, circulation

direction ^: top to bottom of the photoconductor)

• Elastic member • NA

(Example 8)

The electrophotographic photoconductor of Example 8 was

produced similar to that in the Example 1 except altering following

composition of the coating solution for a cross-linked surface layer,

exposure condition, and the method for controlling temperature.

[Coating solution for a cross-linked surface layer]

• A radically polymerizable compound with charge transport

structure • • • 10 parts

Example compound No.54 (molecular weight • 419, number of

functional groups '■ l)

• Radically polymerizable monomer with no charge transport

structure • • • 10 parts

Trimethylol propane triacrylate (by Nippon Kayaku Co., Ltd.,

KAYARAD TMPTA, molecular weight : 296, number of functional

group : 3)

• Photopolymerizable initiator • ^• • 1 part

IRGACUE 184 (by Nippon Kayaku Co., Ltd., molecular

weight : 204)

• Solvent

Tetrahydrofuran • • • 90 parts

(boiling point • 66°C, saturated vapor pressure • .

176mmHg/25°C)

Butyl acetate (boiling point - 126°C, saturated vapor

pressure : 13mmHg/25°C) ^• • ^• 30 parts

[Exposure Condition and Method for Controlling Temperature]

• UV lamp system by Fusion (light intensity : 3300W/cm ² )

• Irradiation chamber atmosphere : air

• Heating medium : water (flow rate • 3.5L/min, circulation

direction •" bottom to top of the photoconductor)

• Elastic member •' NA

(Example 9)

The electrophotographic photoconductor of Example 9 was

produced similar to that in the Example 1 except that a radically

polymerizable monomer having no charge transport structure was

changed to ethoxy bis phenol A diacrylate (by SHINNAKAMURA

Co., Ltd., ABE-300).

(Example 10)

The electrophotographic photoconductor of Example 10 was

produced similar to that in the Example 1 except that the exposure

time for the cross-linked surface layer was lOOsec, and the

thickness of the cross-linked surface layer was 5μm.

(Example 11)

The electrophotographic photoconductor of Example 11 was

produced similar to that in the Example 1 except that a

photoconductive coating solution, of which the charge generating

layer and the charge transport layer were the followings were

coated, dried, and the thickness of the photosensitive layer was

23μm.

-Composition of Photosensitive Layer Coating Solution-

• Titanylphthalocyanin • • • 1 part

^• Charge transport material expressed by the following

Structural Formula • • • 30 parts

• Charge transport material expressed by the following

Structural Formula • • • 20 parts

^• Bis phenol Z polycarbonate (Panlight TS-2050, by TEIJIN

CHEMICALS Ltd.) • • • 50 parts

^• Tetrahydroflan • ^• • 400 parts

(Comparative Example 1)

The electrophotographic photoconductor was produced

similar to that in Example 1 except that a cross-linked surface

layer was not provided and the thickness of a charge transport

layer was set to 27μm.

(Comparative Example 2)

The electrophotographic photoconductor was produced

similar to that in the Example 1 except that a cross-linked surface

layer was formed according to Example 1 of JP-A No. 2001-125297.

The air cooling method was used as a method for controlling the

initial surface temperature of photoconductor to be 25°C.

(Comparative Example 3)

The electrophotographic photoconductor was produced

similar to that in Example 1 except that a cross-linked surface

layer was formed according to Example 2 of JP-A No. 2004-302450

of Example 1. The air cooling method was used as a controlling

method for being the surface temperature of photoconductor to be

50 ⁰ C or less.

(Comparative Example 4)

The electrophotographic photoconductor was produced

similar to that in Comparative Example 3 expect that UV exposing

time was 150sec in Comparative Example 3. The air cooling

method was used as a controlling method for the surface

temperature of the photoconductor; however, surface temperature

of photoconductor was 50 ⁰ C or more.

<Surface Observation>

A surface observation of each electrophotographic

photoconductor at 32-fold magnification was conducted using an

optical microscope (by CARL ZEISS). The results were given in

Table 5.

<Temperature Measurement

A surface temperature of photoconductor at the time of

exposure was measured using a thermocouple. The surface

temperature of photoconductor was measured at lcm intervals over

the length of the photoconductor except for areas 3cm away from

both ends of the photoconductor in order to prevent the

measurement area from being direct hit by exposing light.

Surface temperature of photoconductor was measured during the

exposure. Initial temperature of the central part of the

photoconductor, temperature in 30sec after exposure, maximum

temperature, and the difference between maximum temperature

and minimum temperature of photoconductor circuit just before

exposure in all measurement points were shown in Table 6.

<Measurement of the Post-Exposure Electrical Potential >

In the potential property evaluation equipment shown in

FIG.l, the charging unit 202 was the scorotron system which grid

voltage could be reached till ±1500V, and main high-voltage power

supply had ±lOkV of peak voltage. An exposure unit 203 was used

under the condition that the LD scanning system was 780nm of

light source wavelength, fθ lens focal length was 251mm, main

scanning beam diameter was 68.5μm, vertical scanning beam

diameter was 81.5μm, image static power (intensity) was 0.833mW

to 3.3mW (no filter), writing width was 60mm, lighting frequency

was continuous lighting only, number of polygon mirror planes was

6, polygon revolutions was 6,000rpm to 40,000rpm (variable

rotation), and polygon rotation stability time was 5 sec. A

neutralization unit 204 was used under the condition that light

source LED was around 660nm wavelength, maximum intensity

was l,060μW/cm ² (variable intensity), exposing width was 2mm

width on the photoconductor (2mm away from the surface of the

photoconductor) .

In the potential property evaluation equipment shown in

FIG.l, specific measurement conditions were as follows ¹ image

static power was 0.53mW, exposure energy was 4.0erg/cm ² ,

photoconductor linear speed was 251mm/sec, feed size was 210mm,

recurrence interval was 500ms, the charging unit 202 was 0 degree

position, the surface potential meter 210 was 70 degree position ,

the exposure unit 203 was 90 degree position, the surface potential

meter 211 was 120 degree position, the neutralization unit 204 was

270 degree position, and the charging grid bias was -800V. The

surface potential of the photoconductor 201 measured by the

surface potential meter 210 was -800V. Measurement was

conducted at lcm intervals in the longitudinal direction over the

area which 3cm portion from the edge photoconductor was removed.

Maximum value, minimum value of all measurement points, and

the difference between maximum value and minimum value were

shown in Table 7.

<Durability Test>

Initial dark place potential was set to -700V by the altered

image forming apparatus (by Ricoh Company, Ltd., IMAGIO MF

2200 altered machine) where each electrophotographic

photoconductor shown in Examples and Comparative Examples

was attached to a process cartridge, a semiconductor laser of

780nm wavelength was used as the image exposing light source,

and the contact pressure of cleaning blade was altered 1.5 times.

Then, sheet test was provided, thickness was measured and image

quality was evaluated initially and per 10,000 sheets, and 30,000

sheets of A4 size was tested. As electric property at the end of

sheet test, dark space and exposed area potential over the same

places as the initial dark space potential measured part were

measured. The thickness of the photoconductor was measured by

eddycurrent style thickness measurement apparatus (by Fisher

Instrument). The results were given in Table 8.

<Image Quality Evaluation>

The image quality was evaluated by outputting a halftone

image after the durability test, and by four grades of image density

evenness. The results were given in Table 8.

[Evaluation Criteria]

A : no unevenness in image density

B '■ little unevenness in image density

C - a little unevenness in image density

D ' unevenness in image density

Table 5

From the results shown in Table 5, in Examples 1 to 11 and

Comparative Example 1, it is conceivable that the surface had no

unevenness, the surface has good surface smoothness, the surface

temperature of photoconductor at the time of light-curing was

evenly controlled, and an even cross-linked surface layer was

formed. From here onwards, in Examples of the present invention,

it may be said that the surface smoothness was enough to supply

sufficient safety margin for cleaning.

In contrast, in Comparative Examples 2 to 4, it is

conceivable that there seemed to have partial unevenness for some

parts, polymerization reaction was not evenly progressed because

even surface temperature of photoconductor was not accomplished,

thereby uneven cross-linked layers were formed.

Table 6

From the results in Table 6, in Examples 1 to 11, the surface

temperature of the photoconductor was increased by 10 ⁰ C or more

after 30sec of initial exposure, the difference between the

maximum and the minimum temperature was 20 ⁰ C or less, and the

values were smaller than that in Comparative Examples 2 to 4. It

could be thought that the cross-linked layer was formed through

sufficient and an even polymerization reaction. In Comparative

Examples 2 to 4, the temperature increase after 30sec of exposure

was large, the difference between maximum and minimum

temperature exceeded 30 ⁰ C, and thereby the result indicated that

even cross-linked layer was not achieved.

Table 7

From the results shown in Table 7, in Examples 1 to 11, the

difference between maximum and minimum value of the

post-exposure electrical potential was below 30V, it was found out

that electric property of a cross-linked surface layer was even. On

the other hand, in Comparative Examples 2 to 4, the difference

between maximum and minimum value of the post-exposure

electrical potential was 35V or more, thereby a cross ^{^} linked surface

layer did not have even electric property.

Table 8

From the results shown in Table 8, in the

electrophotographic photoconductor of Examples 1 to 11, wear

volume was small, image density unevenness of the image after

prolonged period durability test did not occur, and the

electrophotographic photoconductor having uniform

electrophotographic property and high wear resistance was

attained. On the other hand, in the photoconductor of the

Comparative Example 1 having no protective layer, wear volume

was large, degree of image density unevenness was poor from the

beginning because even cross -linking was not provided in the

photoconductor of Comparative Examples 2, 3, and 4, and distinct

image density unevenness was generated after durability test.

Industrial Applicability

An image forming method, an image forming apparatus, and

a process cartridge using the electrophotographic photoconductor

of the present invention can maintain high wear resistance for

prolonged periods, have little fluctuation of electric property, have

small the dependencies of places of wear resistance and electric

property, provide superior durability and stable electric property,

and can attain high quality image forming for prolonged periods so

that they can be widely used for full color printer, full color laser

printer, and full color standard paper facsimile machine, or these

complex machines using direct or indirect electrophotographic

multiple color image development system.