TECHNICAL FIELD

The present disclosure relates to a synthetic paper. The present disclosure also relates to a process for preparation of a synthetic paper. The synthetic paper of present disclosure has high tear resistance and can be used in tag applications. The synthetic paper of present disclosure is printable on both sides by UV offset, water and UV Flexo, and thermal transfer printing processes.

BACKGROUND OF THE INVENTION

The polypropylene based BOPP film material used as a synthetic paper preserving resistance to water, oil and grease as compared to conventional papers. However, there is no patent on laminates of blown and cast film for high tear resistance synthetic paper for tag applications and for UV offset, water, UV Flexo, and thermal transfer printing processes.

US 2018/0134014A1 discloses a synthetic paper including one or more layers of a resin film formed from a composition comprising: a polyolefin resin present in an amount of about 40 percent to about 60 percent by weight of the synthetic paper; and a particulate filler having a mean particle size of about 10 pm to about 30 pm, wherein the synthetic paper has a dead fold angle of about 20° to about 30°.

US 4,663,216 discloses a synthetic paper printable in high gloss comprises (1) a multilayer support, (2) a layer of a transparent film of a thermoplastic resin free from an inorganic fine powder formed on one surface of the support (1), and (3) a primer layer of a specific material. The support (1) comprises (la) a base layer of a biaxially stretched film of a thermoplastic resin and a surface and a back layer (lb) and (1c) composed of a monoaxially stretched film of a thermoplastic resin containing from 8 to 65% by weight of an inorganic fine powder. BOPP and Blown films are different in nature (process, raw material and properties). WO 2014/110657 Al discloses a coextruded multilayer film comprising: a core layer comprising at least one random polypropylene copolymer; at least one skin or intermediate layer adjacent to said core layer; wherein said coextruded multilayer film has improved machine direction tear, as determined by ASTM D-1922, that is at least 30% higher compared with a core layer comprising at least one impact polypropylene copolymer. The multilayer thermoplastic films of WO 2014/110657 Al can be produced using a blown film or a cast film processes.

Existed synthetic papers are not suitable for the tag applications as they are having low tear resistance and lack of balance mechanical properties. The existed synthetic paper to date lacks the film rigidity, tear strength, printability with balanced mechanical proprieties for tag applications. Therefore, there is a need for a synthetic paper with balanced mechanical properties in both MD and TD direction along with high tear resistance and low gloss surface with the printability.

OBJECTIVES OF THE INVENTION

The objective of present disclosure is to provide a synthetic paper.

Another objective of present disclosure is to provide a process for preparation of a synthetic paper.

It is an objective of present disclosure to provide a synthetic paper with balanced mechanical properties in both MD and TD direction along with high tear resistance, high opacity and low gloss surface with the printability.

Further an objective of present disclosure is to provide a synthetic paper which has printing layers printable by UV offset, Water, UV flexo and thermal transfer processes.

SUMMARY OF THE INVENTION

The present disclosure provides a synthetic paper comprising:

(i) a middle layer (A) of thermoplastic blown films; (ii) skin opacifying layers (Bl, B2) of thermoplastic cast films; and

(iii) bonding layers (C 1 , C2) present between the middle layer (A) and skin opacifying layers (Bl, B2).

The present disclosure also provides process for preparation of a synthetic paper comprising: coextruding a middle layer (A) of thermoplastic blown films and a skin opacifying layers (B 1 , B2) of thermoplastic cast films by bonding layers (Cl, C2) between the middle layer (A) and skin opacifying layers (Bl, B2) at a temperature in the range of 45-55 °C.

These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following description. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE FIGURES

The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description and accompanying drawings where:

Fig 1 shows a schematic representation for preparation of a synthetic paper.

Fig 2a shows lamination of balanced stretched blown films with cast films (Laminate of thickness 125 microns).

Fig 2b shows lamination of balanced stretched blown films with cast films (Laminate of thickness 150 microns).

Fig 2c shows lamination of balanced stretched blown films with cast films (Laminate of thickness 200 microns).

Fig 2d shows lamination of balanced stretched blown films with cast films (Laminate of thickness 250 microns).

DETAILED DESCRIPTION OF THE INVENTION The present disclosure provides a synthetic paper comprising:

(i) a middle layer (A) of thermoplastic blown films;

(ii) skin opacifying layers (Bl, B2) of thermoplastic cast films; and

(iii) bonding layers (C 1 , C2) present between the middle layer (A) and skin opacifying layers (Bl, B2).

In another embodiment of the present disclosure, the ratio of thickness of thermoplastic blown films to thermoplastic cast films is in the range of 1:0.5- 1:2. Preferably, the intermediate blown film to outer CPP film ratio is 1: 1.52, 1: 1.08, 1:0.63 and 1:0.44.

In further embodiment of the present disclosure, wherein the bonding layers (Cl, C2) are solvent-less water based polyurethane adhesive.

In an embodiment of the present disclosure, the thermoplastic cast films are coextruded thermoplastic resin containing minute particles of an inorganic filler. The inorganic filler is selected from the group consisting of Titanium dioxide (TiCh), Calcium carbonate (CaCCh), Magnesium silicate (MgChSi), Silicon dioxide (SiC ), Barium sulphate (BaSC ) and lithophone (BaOsS2Zn2) or a combination thereof.

In an embodiment of present disclosure, the thermoplastic blown films comprises an inner layer, an intermediate layer and an outer layer in a ratio in the range of 1-2: 1-2.5: 1.

The thermoplastic blown film comprises 50-70 wt% of a high density polyethylene resin, 10-30 wt% of low density polyethylene, 5-20 wt% of inorganic fillers.

Another embodiment of present disclosure provides that the thermoplastic cast film comprises a 4- 16 wt% of a lamination layer, 70-85 wt% of an intermediate layer and 5-15 wt% of a printing layer. In an embodiment of present disclosure, the lamination layer comprises 4-8 wt% antiblock masterbatch, 95 -98 wt% polypropylene random copolymer. The intermediate layer comprises 85-90 wt% of a polypropylene homopolymer and 5-15 wt% of an inorganic filler. The printing layer comprises 0-95 wt% polypropylene homopolymer, 4-8 wt% antiblock masterbatch, 35-55 wt% polypropylene random copolymer, 45-65 wt% of a high density polypropylene and 5-15 wt% of an inorganic filler.

The present disclosure further provides process for preparation of a synthetic paper comprising: coextruding a middle layer (A) of thermoplastic blown films and a skin opacifying layers (B 1 , B2) of thermoplastic cast films by bonding layers (Cl, C2) between the middle layer (A) and skin opacifying layers (Bl, B2) at a temperature in the range of 45-55 °C.

The thermoplastic blown film are produced with 2.4 - 2.7 blow up ratio. Extrusion temperature range used 185 - 200 deg C. Mesh size used 40/60/80. Winding tension: 18 kg, Air cooling Temp: 20 deg C.

The CPP film produced with casting speed 60m/min. Extrusion temperature range used 225 to 260 deg C. Mesh size used 40/60/80. The die temperate was maintained 240 deg C. The chill roll temperature was maintained 28 to 32 deg C.

The present disclosure includes the lamination of the blown film and cast films to produce the high tear resistance synthetic paper ranges thickness from 50 mic to 250 mic which containing thermoplastic polyolefin and fine inorganic minerals. The blown film was produced by co extrusion of the thermoplastics polyolefin and fine inorganic minerals. The tensile strength elongation, hole tear and stiffness are balance in both MD and TD directions. This is due to balance stretching of the blown films. The cast films were produced by coextruded thermoplastic resin containing minute particles of inorganic filler providing a low gloss printing surface.

EXAMPLES The following examples are given by way of illustration of the present disclosure and should not be construed to limit the scope of present disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the subject matter.

Example 1: Preparation of Blown Film:

The blown film having high tear resistance and balance mechanical properties in both MD and TD directions, is a three-decker, respectively inner layer, intermediate layer and outer layer. Three layers part by weight is 33.32% each. The three layer film made of a composition comprising 100 parts by weight of a resin blend of 50-70 wt% of high density polyethylene, 10-30 wt% of low density polyethylene, 5-20 wt% of TiCh filled masterbatch, 5-20 wt% of CaCOs filled masterbatch. The blown film produced with 2.4 - 2.7 blow up ratio. Extrusion temperature range used 185 - 200 deg C. Mesh size used 40/60/80. Winding tension: 18 kg, Air cooling Temp: 20 deg C.

Example 2: Preparation of Cast Film:

The skin opacifying layer is made from the coextruded thermoplastic resin containing minute particles of inorganic filler providing a printing surface. The significance of this film is printability by UV offset, water & UV Flexo, and thermal transfer printing processes. The cast film is a three-decker, is respectively seal or lamination layer, intermediate layer and printing layer. Three layers part by weight is respectively 12.5%, 78.3%, 9.3%; Printing layer raw material is (0-95 wt%) polypropylene homopolymer, (4-8 wt%) antiblock masterbatch, (35-55 wt%) Polypropylene random copolymer, (45-65 wt%) high density polypropylene and (5-15 wt%) CaCO3 filled filler masterbatch. The intermediate layer raw material is (85-90 wt%) polypropylene homopolymer and (5-15 wt%) TiO2 filled white masterbatch and lamination layer material is (4-8 wt%) antiblock masterbatch, (95 -98 wt%) polypropylene random copolymer.

Example 3: Preparation of laminate/synthetic paper: A schematic representation of preparation of a synthetic paper is given in figure 1. The synthetic paper is prepared by coextruding a middle layer of thermoplastic blown films and a skin opacifying layers of thermoplastic cast films by bonding layers between the middle layer and skin opacifying layers at a temperature in the range of 45-55 °C. The synthetic paper as obtained by this process has a thickness of 125 mircons (Fig. 2(a)) having structure as:

CPP film of thickness 38 microns

Blown film of thickness 50 microns

CPP film of thickness 38 microns.

The Synthetic paper has excellent tear resistance and balance mechanical properties and imparting strength to the laminate. A synthetic

Example 4:

A synthetic paper (fig. 2(b)) prepared by the process as explained in Example 3, having 150 microns thick laminate structure as:

CPP film of thickness 38 microns

Blown film of thickness 70 microns

CPP film of thickness 38 microns.

Example 5:

A synthetic paper (fig. 2(c)) prepared by the process as explained in Example 3, having 200 microns thick laminate structure as:

CPP film of thickness 38 microns

Blown film of thickness 50 microns

Blown film of thickness 70 microns

CPP film of thickness 38 microns.

Example 6:

A synthetic paper (fig. 2(c)) prepared by the process as explained in Example 3, having 250 microns thick laminate structure as: CPP film of thickness 38 microns

Blown film of thickness 50 microns

Blown film of thickness 70 microns

Blown film of thickness 50 microns CPP film of thickness 38 microns.

Example 7:

Experimental details/testing results: The high tear resistance synthetic paper as per the invention is the laminated structure of the blown film and CPP film having balance mechanical properties in MD and TD direction. The high tear resistance and tensile strength is due to balance stretching / orientation in both MD and TD directions in the intermediate blown film. The fast quenching of the outer CPP film particularly with polyolefins increases the elongation. The properties of the laminate structures represented in Figure 2(a-d), are given in Table 1 below:

Table 1: The properties of the laminate structures

Example 8:

Below are the data on tear strength of commercially available synthetic papers and the synthetic paper as per the invention. Table 2: Tear strength of the synthetic paper

From table 2, it is evident that hole tear resistance increases with increase in the thickness and ratio/amount of the blown film. The high tear resistance synthetic paper of present invention is the laminated structure of the blown film and CPP film whereas the commercially available synthetic paper are the single layer structures.

Advantages of laminate of present invention The product has been engineered to be non-tearable, displaying excellent tear resistance and has been designed specifically for tag applications. It is printable on both sides by UV offset, water, UV Flexo, and thermal transfer printing processes. Some of the typical tag applications include garment hang tags, horticulture identification tags, tree tags, cattle identification tags and airport transfer tags. Coextruded white opaque both side matte polyolefin based films laminate which resembles paper in appearance. The synthetic paper as per the invention has good dimensional stability and excellent printability by UV offset, Water and UV flexo and thermal transfer printing process, die punched and perforated.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the subject matter should not be limited to the description of the preferred embodiment contained therein.