AND USING THE SAME

TECHNICAL FIELD

The present disclosure broadly relates to abrasive articles and methods of making and using them.

BACKGROUND

Stroke sanders are used to put specified finishes on large, flat metal parts. A stroke sander is made up basically of three parts: the large table to hold the workpiece, a movable abrasive belt suspended between two wheels, and a movable platen located inside the belt track. The platen can be manually operated or be integrated into the stroke sander. Similarly, file belt sanders often use a graphite platen extension arm. In use, the platen urges the abrasive belt against the workpiece and is usually coated with a low friction material such as, for example, graphite to reduce friction between the backing of the abrasive belt and the platen.

Surface conditioning belts generally have a lofty open nonwoven fiber web needle tacked to a fabric backing and then coated with abrasive particles in a binder material. The process of needle tacking results in some of the fibers of the lofty open nonwoven fiber web being pushed through the backing such that they protrude from the back side. These protruding fibers cause undesirable friction against the platen. To combat this problem, it is known to extrude a thermoplastic polymer such as Nylon 6,6 polyamide onto the entire back side of the fabric backing to render a smooth surface.

SUMMARY

Advantageously, and unexpectedly, surface conditioning articles according to the present disclosure, in endless belt form, are suitable for at least stroke sanding applications and have comparable low friction properties as similar belts with low friction coatings covering the entire back surface of the backing. Moreover, the surface conditioning belts are cheaper to manufacture and reduce waste after the belt is worn out.

In a first embodiment, the present disclosure provides a surface conditioning article comprising: a fabric backing having first and second opposed major sides; a lofty open nonwoven fiber web comprising entangled fibers disposed on and secured to the first major side of the fabric backing, wherein at least some of the entangled fibers extend through the fabric backing from the first side to the second side; abrasive particles secured to the lofty open nonwoven fiber web disposed on the first major side, wherein the abrasive particles are secured to the lofty open nonwoven fiber web by a binder material; and at least one raised feature comprising a at least one raised feature disposed on a minor portion of the second major side of the fabric backing, wherein the entangled fibers extending through the fabric backing have an average diameter, wherein the at least one raised feature has a height of at least 8 times the average diameter, and wherein the at least one raised feature comprises an organic polymer.

In some embodiments, the surface conditioning article is in the form of an endless belt.

In another aspect, the present disclosure provides a method of making a surface conditioning article, the method comprising the steps: providing a fabric backing having first and second opposed major sides; needle tacking a lofty open nonwoven fiber web and the fabric backing, wherein the lofty open nonwoven fiber web comprises entangled fibers, such that some of the entangled fibers extend through the fabric backing from the first side to the second side; disposing a mixture of abrasive particles and a curable binder precursor onto the lofty open nonwoven fiber web adjacent to the first major side of the fabric backing; at least partially curing the curable binder precursor; and disposing at least one raised feature on a minor portion of the second major side of the fabric backing of the fabric backing, wherein the entangled fibers extending through the fabric backing have an average diameter, wherein the at least one raised feature has a height of at least 8 times the average diameter, and wherein the at least one raised feature comprises an organic polymer.

Often, the method further comprises converting the surface conditioning article into an endless belt.

Surface conditioning articles according to the present disclosure are useful, for example, for abrading a workpiece. In typical use, abrasive particles in the surface conditioning article are frictionally contacted with a workpiece moved relative to the workpiece to abrade the workpiece.

As used herein:

"ASTM" refers to ASTM International, West Conshohocken, Pennsylvania; and

"stripe" refers to a relatively long, narrow band of material.

Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of exemplary surface conditioning article 100 according to the present disclosure.

FIG. 2 is a schematic cross-sectional view of surface conditioning article taken along line 2-2 in FIG. 1.

FIG. 3 is a schematic backside view (i.e., opposite the abrading surface) of exemplary surface conditioning article 300 according to the present disclosure.

FIG. 4 is a schematic backside view of exemplary surface conditioning article 400 according to the present disclosure. FIG. 5 is a schematic backside view of exemplary surface conditioning article 500 according to the present disclosure.

FIG. 6 is a schematic backside view of exemplary surface conditioning article 600 according to the present disclosure.

FIG. 7 is a schematic backside view of exemplary surface conditioning article 700 according to the present disclosure.

FIG. 8 is a schematic backside view of exemplary surface conditioning article 800 according to the present disclosure.

Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

Referring now to FIG. 1, surface conditioning article 100 (shown as an endless belt) comprises nonwoven abrasive layer 110, raised features 120 (shown as stripes), fabric backing 130. Fabric backing 130 has first and second surfaces (132, 134). Fibers 165 extend through fabric backing 130. Optionally, but commonly, the belt may further comprise a splice (e.g., a butt splice, not shown). Various types of splices are known in the abrasive belt art.

Referring now to FIG. 2, nonwoven abrasive layer 110 comprises a lofty open nonwoven fiber web and secured to the lofty open nonwoven fiber web by a binder material (not shown), raised features 120, fabric backing 130, and fibers 165 that extend through fabric backing 130.

Useful fabric backings include woven fabrics and knitted fabrics, for example. Exemplary materials to provide the fabric backing include conventional woven cloth backing materials utilized in coated abrasive products. Such woven backing materials include woven or knit nylon, woven or knit polyester, or cotton cloth such as, for example, drills, jeans, or greige cloth fabric with polyester greige cloth being preferred. Such fabrics are typically treated with a sizing agent.

Typically, the fabric backing is porous and stretch-resistant, although this is not a requirement. For example, stretch-resistance may be imparted to a stretchable fabric backing by virtue of the raised features in some embodiments. Often, the fabric backing has a stretch value of less than about 5 percent, preferably less than about 2 percent, if subjected to a stress of 175 x 1(U newtons (N) per lineal meter width. In some embodiments, the fabric backing may comprise a woven stretch-resistant material comprising plain weave fabric having openings between the warp and fill yams of at least about 0.10 millimeter (mm). The fabric should typically be selected so that it is compatible with materials and process conditions utilized in the preparation of the surface conditioning article.

The fabric backing should generally be sufficiently flexible to be useful for at least one abrading process, preferably stroke sanding. Lofty open nonwoven fiber webs suitable for use in the present disclosure are known in the abrasives art. Generally, they comprise a web of fibers. The fibers may comprise continuous fiber, staple fiber, or a combination thereof. For example, the fiber web may comprise staple fibers having a length of at least about 20 mm, at least about 30 mm, or at least about 40 mm, and less than about 110 mm, less than about 85 mm, or less than about 65 mm, although shorter and longer fibers (e.g., continuous filaments) may also be useful. The fibers may have a fineness or linear density of at least about 1.7 decitex (dtex, i.e., grams/10000 meters), at least about 6 dtex, or at least about 17 dtex, and less than about 560 dtex, less than about 280 dtex, or less than about 120 dtex, although fibers having lesser and/or greater linear densities may also be useful. Mixtures of fibers with differing linear densities may be useful, for example, to provide an abrasive article that upon use will result in a specifically preferred surface finish.

The fibers can be made of any suitable material. For example, the fibers can be natural fibers, synthetic fibers, or mixtures of natural and synthetic fibers. Examples of synthetic fibers can include polyester, nylon, polypropylene, acrylonitrile, rayon, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymers, vinyl chloride-acrylonitrile copolymers, or a combination thereof. Examples of suitable natural fibers include cotton, wool, jute, and hemp. The fiber may be of virgin material or of recycled or waste material, for example, reclaimed from garment cuttings, carpet manufacturing, fiber manufacturing, or textile processing. The fiber can be homogenous or a composite such as a bicomponent fiber (e.g., a co-spun sheath-core fiber). The fibers can be continuous filaments such as those formed by an extrusion process.

The fibers can have any suitable shape. The fibers can have a circular cross-section. In some embodiments, the fibers can have a non-circular cross sectional shape or can be a blend of fibers having a circular and a non-circular cross sectional shape. Non-circular cross sectional shapes can include triangular, delta, H-shaped, trilobal, rectangular, square, dog-bone, ribbon-shaped, and oval. The diameter of a fiber having a non-circular cross section is the largest dimension of the non-circular crosssection of the fiber. The fibers can have a substantially uniform diameter, wherein the largest dimension of the cross section of each fiber is substantially the same from one end of the fiber to the other.

The fibers can have a single diameter (e.g., a single uniform diameter). The lofty open nonwoven fiber web can be substantially free of fibers have a different diameter than the single diameter. The single diameter can be about 0.01 denier (e.g., grams per 9000 meters) to about 1000 denier, or about 3 denier to about 40 denier, or about 0.01 denier or less, or less than, equal to, or greater than about 0.1 denier, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900, or about 1000 denier or more.

In some embodiments, the fibers can have more than one diameter. For example, the fibers in the lofty open nonwoven fiber web can include first fibers having a first diameter (e.g., a first uniform diameter), and second fibers having a second diameter (e.g., second uniform diameter), wherein the first diameter is different than the second diameter. In various embodiments, the fibers can include any suitable number of diameters, such as further including third fibers having a third diameter, fourth fibers having a fourth diameter, and the like.

In a lofty open nonwoven fiber web including first fibers and second fibers, the first fibers can form any suitable proportion of the fibers in the nonwoven web. For example, the first fibers can be about 0.001 weight percent to about 99.999 weight percent of the fibers in the nonwoven web, or about 10 weight percent to about 50 weight percent, or about 15 weight percent to about 40 weight percent, or about 0.001 weight percent or less, or less than, equal to, or greater than about 0.01 weight percent, 0.1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 99.9, or 99.99 weight percent, or about 99.999 weight percent or more of the fibers in the nonwoven web. The first fibers can be about 0.01 denier to about 1000 denier, or about 3 denier to about 40 denier, or about 0.01 denier or less, or less than, equal to, or greater than about 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900, or even 1000 denier or more.

In a lofty open nonwoven fiber web including first fibers and second fibers, the second fibers can form any suitable proportion of the fibers in the nonwoven web. For example, the second fibers can be about 0.001 weight percent to about 99.999 weight percent of the fibers in the nonwoven web, or about 50 weight percent to about 90 weight percent, or about 65 weight percent to about 85 weight percent, or about 0.001 weight percent or less, or less than, equal to, or greater than about 0.01 weight percent, 0.1,

I,2,4, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 52, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 88, 90, 95, 96, 97, 98, 99, 99.9, 99.99 weight percent, or about 99.999 weight percent or more of the fibers in the nonwoven web. The second fibers can be about 0.01 denier to about 1,000 denier, or about 3 denier to about 40 denier, or about 0.01 denier or less, or less than, equal to, or greater than about 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900, or 1000 denier or more.

In a lofty open nonwoven web including first fibers and second fibers, the first fibers can have a smaller diameter than the second fibers. For example, the first fibers can have a denier that is about 1 denier to about 500 denier less than the second fibers, or about 5 denier to about 50 denier less than the second fibers, or about 1 denier or less, or less than, equal to, or greater than about 2, 3, 4, 5, 6, 7, 8, 9, 10,

I I, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, or 500 denier or more. In some embodiments, the lofty open nonwoven web includes first fibers having a denier or about 3 that are about 25 weight percent of the fibers in the nonwoven web, and second fibers having a denier of about 15 that are about 75 weight percent of the fibers in the nonwoven web. In some embodiments, the nonwoven web can be substantially free of fibers other than the first fibers and second fibers.

The lofty open nonwoven fiber web may be made, for example, by conventional nonwoven techniques such as, for example, air laid, carded, stitch bonded, spun bonded, wet laid, and/or melt blown procedures. Air laid fiber webs may be prepared using equipment such as, for example, that available as RANDO WEBBER from Rando Machine Company of Macedon, New York.

The lofty open nonwoven fiber web is typically selected to be compatible with adhering binders and abrasive particles while also being compatible with other components of the surface conditioning article, and typically can withstand processing conditions (e.g., temperatures) such as those employed during application and curing of the curable binder precursor. The fibers may be chosen to affect properties of the abrasive article such as, for example, flexibility, elasticity, durability or longevity, abrasiveness, and finishing properties. Examples of fibers that may be suitable include natural fibers, synthetic fibers, and mixtures of natural and/or synthetic fibers. Examples of synthetic fibers include those made from polyester (e.g., polyethylene terephthalate), nylon (e.g., hexamethylene adipamide, polycaprolactam), polypropylene, acrylonitrile (i.e., acrylic), rayon, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymers, and vinyl chloride-acrylonitrile copolymers. Examples of suitable natural fibers include cotton, wool, jute, and hemp. The fiber may be of virgin material or of recycled or waste material, for example, reclaimed from garment cuttings, carpet manufacturing, fiber manufacturing, or textile processing. The fiber may be homogenous or a composite such as a bicomponent fiber (e.g., a co-spun sheath-core fiber). The fibers may be tensilized and crimped but may also be continuous filaments such as those formed by an extrusion process. Combinations of fibers may also be used.

Prior to coating and/or impregnation with a binder precursor composition, the fiber web typically has a weight per unit area (i.e., basis weight) of at least about 50 grams per square meter (gsm), at least about 100 gsm, or at least about 150 gsm; and/or less than about 600 gsm, less than about 500 gsm, or less than about 400 gsm, as measured prior to any coating (e.g., with the curable binder precursor or optional pre-bond resin), although greater and lesser basis weights may also be used. In addition, prior to impregnation with a curable binder precursor, the fiber web typically has a thickness of at least about 3 mm, at least about 6 mm, or at least about 10 mm; and/or less than about 100 mm, less than about 50 mm, or less than about 25 mm, although greater and lesser thicknesses may also be useful.

Frequently, as known in the abrasives art, it is useful to apply a prebond resin to the nonwoven fiber web prior to coating with the curable binder precursor. The prebond resin serves, for example, to help maintain the nonwoven fiber web integrity during handling and may also facilitate bonding of the urethane binder to the nonwoven fiber web. Examples of prebond resins include phenolic resins, urethane resins, hide glue, acrylic resins, urea-formaldehyde resins, melamine-formaldehyde resins, epoxy resins, and combinations thereof. The amount of pre-bond resin used in this manner is typically adjusted toward the minimum amount consistent with bonding the fibers together at their points of crossing contact. In those cases, wherein the nonwoven fiber web includes thermally bondable fibers, thermal bonding of the nonwoven fiber web may also be helpful to maintain web integrity during processing.

The lofty open nonwoven fiber web is at least partially secured to a first major side of the fabric backing by means of needle tacking (i.e., needle punching). Needle tacking is a method of attaching nonwoven webs to a fabric. Barbed needles pass through the nonwoven web and penetrate the fabric, the barbed needles pulling along fibers of the fiber web. The needle thereafter is retracted, leaving individual or collections of fibers of the web penetrating through and extending from the opposite major side of attached to the fabric. Selection of needles and determination of the degree of needle tacking necessary to provide useful abrasive articles is within the capabilities of those having ordinary skill in the art. A conventional needle loom such as, for example, one commercially available from the James Hunter Machine Company is typically useful.

Abrasive particles can be secured to the lofty open nonwoven fiber web, for example, by applying a slurry of abrasive particles in a curable binder precursor. Any suitable coating technique may be used such as for example, roll coating and spray coating. Of these, spray coating is often convenient and effective.

Alternatively, the curable binder precursor may be coated first onto the lofty open nonwoven fiber web followed by application of the abrasive particles (e.g., by drop coating, electrostatic coating, or spray coating).

Any curable (i.e., thermosetting) material may be included in the curable binder precursor. Many are known in the abrasives art, including, for example, glue, phenolic resin, aminoplast resin, ureaformaldehyde resin, melamine-formaldehyde resin, urethane resin, free-radically polymerizable polyfunctional (methjacrylate (e.g., aminoplast resin having pendant a,P-unsaturated groups, acrylated urethane, acrylated epoxy, acrylated isocyanurate), epoxy resin (including bis-maleimide and fluorene- modified epoxy resins), isocyanurate resin, film forming polymer dispersions/latexes (e.g., polyurethane dispersions, poly(ethylene-co-vinyl acetate) dispersions, and acrylic dispersions), and combinations thereof.

Curable binder precursors may further comprise optional additives such as abrasive particle surface modification additives, coupling agents, crosslinking agents, plasticizers, fillers, expanding agents, fibers, antistatic agents, diluents, antioxidants, heat stabilizers, flame retardants, suspending agents, photosensitizers, lubricants, wetting agents, surfactants, pigments, dyes, UV stabilizers, and suspending agents. The amounts of these materials are generally selected to provide the properties desired.

Examples of useful fillers include metal carbonates (such as calcium carbonate, calcium magnesium carbonate, sodium carbonate, magnesium carbonate), silica (such as quartz, glass beads, glass bubbles and glass fibers), silicates (such as talc, clays, montmorillonite, feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate), metal sulfates (such as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum, vermiculite, sugar, wood flour, aluminum trihydrate, carbon black, metal oxides (such as calcium oxide, aluminum oxide, tin oxide, titanium dioxide), metal sulfites (such as calcium sulfite), thermoplastic particles (such as polycarbonate, polyetherimide, polyester, polyethylene, poly(vinyl chloride), polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polymers, polyurethanes, nylon particles) and thermosetting particles (such as phenolic bubbles, phenolic beads, polyurethane foam particles and the like). The filler may also be a salt such as a halide salt. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride. Examples of metal fillers include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Other fillers can include sulfur, organic sulfur compounds, graphite, lithium stearate, and metallic sulfides.

Curing conditions for the curable binder precursor will generally depend on the nature of the binder precursor(s) selected and will be known to those of ordinary skill in the abrasives art. Examples include amine hardeners (e.g., dicyandiamide) for epoxy resins, cationic (photo)catalysts for epoxy resins, free radical polymerization initiators (e.g., thermal initiators such as peroxides and/or photoinitiators such as benzophenones and phosphine oxides). Heat (e.g., from an oven, superheated steam, or infrared lamps) and/or actinic radiation (e.g., from an ultraviolet and/or visible light source) may be used to cure the curable binder precursor. Mere partial curing of the curable binder precursor may be sufficient in some case, but preferably the curable binder precursor is at least substantially cured.

Examples of useful abrasive particles include: fused aluminum oxide, heat treated aluminum oxide, white fused aluminum oxide, black silicon carbide, green silicon carbide, titanium diboride, boron carbide, tungsten carbide, titanium carbide, diamond, cubic boron nitride, garnet, fused alumina zirconia, sol gel abrasive particles, silica, iron oxide, chromia, ceria, zirconia, titania, silicates, metal carbonates (such as calcium carbonate (e.g., chalk, calcite, marl, travertine, marble and limestone), calcium magnesium carbonate, sodium carbonate, magnesium carbonate), silica (e.g., quartz, glass beads, glass bubbles and glass fibers) silicates (e.g., talc, clays, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate) metal sulfates (e.g., calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum, aluminum trihydrate, graphite, metal oxides (e.g., tin oxide, calcium oxide), aluminum oxide, titanium dioxide) and metal sulfites (e.g., calcium sulfite), metal particles (e.g., tin, lead, copper), plastic abrasive particles formed from a thermoplastic material (e.g., polycarbonate, polyetherimide, polyester, polyethylene, polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polymers, polyvinyl chloride, polyurethanes, nylon), plastic abrasive particles formed from crosslinked polymers (e.g., phenolic resins, aminoplast resins, urethane resins, epoxy resins, melamine-formaldehyde, acrylate resins, acrylated isocyanurate resins, urea-formaldehyde resins, isocyanurate resins, acrylated urethane resins, acrylated epoxy resins), and combinations thereof. The abrasive particles may also be agglomerates or composites that include additional components, such as, for example, a secondary binder. Criteria used in selecting abrasive particles used for a particular abrading application typically include abrading life, rate of cut, substrate surface finish, grinding efficiency, and product cost.

Useful abrasive particles may also include shaped abrasive particles (e.g., precisely-shaped abrasive particles). Details concerning such abrasive particles and methods for their preparation can be found, for example, in U.S. Pat. No. 8,142,531 (Adefris et al.); 8,142,891 (Culler et al.); and 8,142,532 (Erickson et al.); and in U.S. Pat. Appl. Publ. No. 2012/0227333 (Adefris et al.); 2013/0040537 (Schwabel et al.); and 2013/0125477 (Adefris).

The amounts of each components to include is within the capability of those of ordinary skill in the art.

Surface conditioning article according to the present disclosure advantageously include at least one raised feature disposed on a minor portion of the major side of the fabric backing that is opposite the lofty open nonwoven fiber web.

Generally, it is desirable to provide the raised feature(s) with sufficient coverage to space the fabric backing away from rollers and/or the platen if stroke sanding. Accordingly, if a single raised feature is present it is preferably substantially coextensive with the second major surface of the fabric backing such as, for example, in the case of a network (e.g., a honeycomb pattern or rectangular array) of ribs that are joined together to form a single raised feature. Often, more than one discrete raised feature will be present. In such cases, the raised features are preferably spaced apart so as to provide a substantially uniform coverage and/or substantially uniform density of raised features across the second major surface (i.e., the backside) of the fabric backing, although this is not a requirement. Generally, any configuration of the raised features that provides separation of the fabric backing and guide rollers, or the platen during stroke sanding, may be used.

FIGS. 3-8 illustrate various configurations of raised features according to the present disclosure.

Referring now to FIG. 3, exemplary surface conditioning article 300 has raised features in a pattern of longitudinal parallel wavy stripes 330.

Referring now to FIG. 4, exemplary surface conditioning article 400 has a single raised feature having a rectangular grid pattern 430.

Referring now to FIG. 5, exemplary surface conditioning article 500 has raised features in a pattern of parallel stripes 530 that are oriented perpendicular to its longitudinal direction.

Referring now to FIG. 6, exemplary surface conditioning article 600 has raised features in a pattern of parallel stripes 630 that are oriented at a bias to its longitudinal direction.

Referring now to FIG. 7, exemplary surface conditioning article 700 has raised features in a pattern of parallel broken stripes 730 that are oriented along its longitudinal direction.

Referring now to FIG. 8, exemplary surface conditioning article 800 has raised features in a pattern of parallel unbroken stripes 830 that are oriented along its longitudinal direction. Other configurations of the raised feature(s) will often be used. For example, the raised feature(s) may comprise a regular or random pattern of raised dots, stripes, geometric and/or artistic designs or text (e.g., a trademark or logo), which may have uniform or varied spacing from adjacent raised features. Often the chosen configuration of the raised feature(s) will take into consideration at least one of the following attributes: i) the amount of material required to form the raised feature(s) and its associated material cost; ii) the technical difficulty required to form the raised feature(s); iii) the process speed for forming the raised feature(s); and any adverse changes to abrading performance that may be caused by the raised feature(s); iv) and the reduction in friction (e.g., the platen during stroke sanding) with the second side of the surface conditioning article during use.

The raised feature(s) may have any length and/or width but must be less than a complete coating of the back side of the fabric backing. Often, the raised feature(s) will have a width of at least 1 millimeter (mm), at least 2 mm, at least 3 mm, at least 4 mm, or even at least 8 mm up to 16 mm, 32 mm, 64 mm, 128 mm, or even 256 mm, although this is not a requirement. Often, the raised feature(s) will have a length of at least 1 mm, at least 16 mm, at least 64 mm, at least 256 mm, or even at least 1000 mm, or even up to the entire length of the surface conditioning article, or more (for example, an oscillating longitudinal stripe) although this is not a requirement.

The distance between raised features may have any value; however, in the case of parallel stripes, elements of a regular array, grid lines in the case of a lattice pattern, a spacing between raised features of 0.25 to 2.0 centimeters, 0.9 to 1.6 centimeters, or even 1.2 to 1.4 centimeters may be desirable.

To ensure sufficient clearance, the raised feature(s) may have a height of at least 0.3 mm, at least 0.6 mm, or even at least 8 times the average diameter of the fibers extending through the fabric backing, although this is not a requirement. In some embodiments, the at least one raised feature extends from 0.2 mm to 2.0 mm, preferably from 0.25 mm to 1.4 mm, and more preferably from 0.3 mm to 0.8 mm away from the second major side of the fabric backing.

Combinations of raised features with different shapes, heights, widths, and/or lengths may also be used.

Often, the raised feature(s) is/are disposed at least 1 percent, but less than 50 percent, less than 40 percent, less than 30 percent, less than 20 percent, or even less than 10 percent of the second major side of the fabric backing, although this is not a requirement.

The raised features comprise an organic polymer. Exemplary polymers include thermosetting polymers as described for the at least partially cured binders hereinbefore and/or thermoplastic organic polymers. For example, thermoplastic raised features may be melt extruded or coated from a needle/nozzle dispenser (e.g., as a mixture in solvent) as continuous stripes onto the back side of the fabric backing. Likewise, a thermosetting polymer or a curable composition containing a thermosetting polymer may be coated from a needle/nozzle dispenser (a hollow needle or nozzle), gravure roll, or rotary stencil). Of these, needle coating, is often preferred, and has the advantage that heating is typically not required, although it may be desired to include a solvent and/or reactive diluent. Such methods are within the capability of those having ordinary skill in the art.

Exemplary thermoplastic polymers include polyamides (e.g., nylon-6, 6, polycaprolactam), polyolefins (e.g., polyethylene, polypropylene), polyesters (e.g., polyethylene terephthalate), fluorinated thermoplastics.

Curable compositions containing thermosetting polymers may include the curable binder precursors, including their optional additives and conditions for curing them, that are described hereinabove.

Optionally, the raised features may further comprise a low-friction additive dispersed in the organic polymer. Examples may include silicones, waxes, graphite, hexagonal boron nitride, and/or fluorinated melt additives.

To maintain sufficient flexibility for use in stroke sanding, the at least one raised feature may exhibit a glass transition temperature that is less than or equal to 60°C according to ASTM test method D418-15 "Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry", although this is not a requirement.

The surface conditioning article may have any desired form such as, for example, a hand pad or a belt, typically an endless belt containing a splice. Splices are well-known in the art and many are commercially available. Such endless belts may be used with a stroke sander to abrade a surface of a workpiece (e.g., a metal workpiece).

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a surface conditioning article comprising: a fabric backing having first and second opposed major sides; a lofty open nonwoven fiber web comprising entangled fibers disposed on and secured to the first major side of the fabric backing, wherein at least some of the entangled fibers extend through the fabric backing from the first side to the second side; abrasive particles secured to the lofty open nonwoven fiber web disposed on the first major side, wherein the abrasive particles are secured to the lofty open nonwoven fiber web by a binder material; and at least one raised feature disposed on a minor portion of the second major side of the fabric backing, wherein the entangled fibers extending through the fabric backing have an average diameter, wherein the at least one raised feature has a height of at least 8 times the average diameter, and wherein the at least one raised feature comprises an organic polymer.

In a second embodiment, the present disclosure provides a surface conditioning article according to the first embodiment in the form of an endless belt.

In a third embodiment, the present disclosure provides a surface conditioning article according to the first or second embodiment, wherein the at least one raised feature extends from 0.70 to 1.04 millimeters away from the second major side of the fabric backing. In a fourth embodiment, the present disclosure provides a surface conditioning article according to any of the first to third embodiments, wherein the organic polymer comprises a thermoset polymer.

In a fifth embodiment, the present disclosure provides a surface conditioning article according to any of the first to fourth embodiments, wherein the organic polymer comprises a thermoplastic polymer.

In a sixth embodiment, the present disclosure provides a surface conditioning article according to any of the first to fifth embodiments, wherein the at least one raised feature further comprises a low friction additive dispersed in the organic polymer.

In a seventh embodiment, the present disclosure provides a surface conditioning article according to any of the first to sixth embodiments, wherein the at least one raised feature comprises stripes.

In an eighth embodiment, the present disclosure provides a surface conditioning article according to the seventh embodiment, wherein the stripes are linear.

In a ninth embodiment, the present disclosure provides a surface conditioning article according to the seventh embodiment, wherein the stripes are wavy.

In a tenth embodiment, the present disclosure provides a surface conditioning article according to any of the seventh to ninth embodiments, wherein the stripes are parallel.

In an eleventh embodiment, the present disclosure provides a surface conditioning article according to any of the first to sixth embodiments, wherein the at least one raised feature comprises an array of discrete elements.

In a twelfth embodiment, the present disclosure provides a surface conditioning article according to any of the first to sixth embodiments, wherein the at least one raised feature comprises a network of interconnected lines.

In a thirteenth embodiment, the present disclosure provides a surface conditioning article according to any of the first to twelfth embodiments, wherein the at least one raised feature exhibits a glass transition temperature that is less than or equal to 60°C according to ASTM test method D418-15 "Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry".

In a fourteenth embodiment, the present disclosure provides a surface conditioning article according to any of the first to thirteenth embodiments, wherein the at least one raised feature is disposed on less than 50 percent of the second major side of the fabric backing.

In a fifteenth embodiment, the present disclosure provides a surface conditioning article according to any of the first to thirteenth embodiments, wherein the at least one raised feature is disposed on less than 10 percent of the second major side of the fabric backing.

In a sixteenth embodiment, the present disclosure provides a method of making a surface conditioning article, the method comprising the steps: providing a fabric backing having first and second opposed major sides; needle tacking a lofty open nonwoven fiber web and the fabric backing, wherein the lofty open nonwoven fiber web comprises entangled fibers, such that some of the entangled fibers extend through the fabric backing from the first side to the second side; disposing a mixture of abrasive particles and a curable binder precursor onto the lofty open nonwoven fiber web adjacent to the first major side of the fabric backing; at least partially curing the curable binder precursor; and disposing at least one raised feature on a minor portion of the second major side of the fabric backing of the fabric backing, wherein the entangled fibers extending through the fabric backing have an average diameter, wherein the at least one raised feature has a height of at least 8 times the average diameter, and wherein the at least one raised feature comprises an organic polymer.

In a seventeenth embodiment, the present disclosure provides a method according to the sixteenth embodiment, further comprising converting the surface conditioning article into an endless belt.

In an eighteenth embodiment, the present disclosure provides a method according to the sixteenth or seventeenth embodiment, wherein the steps are consecutive.

In a nineteenth embodiment, the present disclosure provides a method according to any of the sixteenth to eighteenth embodiments, wherein the organic polymer comprises a thermoset polymer.

In a twentieth embodiment, the present disclosure provides a method according to any of the sixteenth to nineteenth embodiments, wherein the organic polymer comprises a thermoplastic polymer.

In a twenty -first embodiment, the present disclosure provides a method according to any of the sixteenth to twentieth embodiments, wherein the at least one raised feature further comprises a low friction additive dispersed in the organic polymer.

In a twenty-second embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -first embodiments, wherein the at least one raised feature comprises stripes.

In a twenty -third embodiment, the present disclosure provides a method according to the twenty second embodiment, wherein the stripes are linear.

In a twenty -fourth embodiment, the present disclosure provides a method according to the twenty second embodiment, wherein the stripes are wavy.

In a twenty -fifth embodiment, the present disclosure provides a method according to the twenty second embodiment, wherein the stripes are parallel.

In a twenty-sixth embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -first embodiments, wherein the at least one raised feature comprises an array of discrete elements.

In a twenty-seventh embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -first embodiments, wherein the at least one raised feature comprises a network of interconnected lines.

In a twenty-eighth embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -first embodiments, wherein the at least one raised feature exhibits a glass transition temperature that is less than or equal to 60°C according to ASTM test method D418-15 "Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry".

In a twenty -ninth embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -eighth embodiments, wherein the at least one raised feature is disposed on less than 30 percent of the second major side of the fabric backing.

In a thirtieth embodiment, the present disclosure provides a method according to any of the sixteenth to twenty -ninth embodiments, wherein the at least one raised feature is disposed on less than 10 percent of the second major side of the fabric backing.

In a thirty -first embodiment, the present disclosure provides a method according to any of the sixteenth to thirtieth embodiments, wherein said disposing the at least one raised feature comprises providing the at least one raised feature as a solution or dispersion in a liquid vehicle, and wherein the method further comprises removing at least a portion of the liquid vehicle.

In a thirty-second embodiment, the present disclosure provides a method according to any of the sixteenth to thirty -first embodiments, wherein the at least one raised feature extends from 0.70 to 1.04 millimeters away from the second major side of the fabric backing.

Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Table 1 below lists abbreviations and materials used in the examples.

TABLE 1

EXAMPLE 1

An air laid nonwoven web was formed using 192 grams per square meter (g/m ² ) FIB using a web forming machine, available as RANDO- WEBBER from the Rando Machine Corporation of Macedon, New York. The air laid fiber web was then placed upon a polyester greige sateen, heat set, destretched woven cloth which had a basis weight of 260 g/m ² and is available from Milliken, Inc., Spartanburg, South Carolina. The air laid web was then needled into and partially through the greige cloth. The needled composite was roll coated with the resin mixture reported in Table 2 and was then cured in an oven for about 5 minutes at 152 degrees Celsius (°C) to achieve a dry resin weight of 205 g/m ² . TABLE 2

A needle die similar to the coating apparatus shown in FIG. 1 of U.S. Pat. No. 10,357,795 (O'Hare et al.) was then used to coat a plurality of linear stripes with a spacing between stripes of 13 mm on the fabric backing side opposite the air laid nonwoven web using the mixture reported in Table 3. The coating was then cured in an oven at 143 °C for about 5 minutes to achieve an added dry weight of 163 g/m .

TABLE 3

An abrasive slurry mix was then applied at a wet weight of 628 g/m using spray coating to coat the air laid nonwoven web (opposite the cured needle coating side) using the mixture reported in Table 4. The abrasive slurry mix was then cured in an oven at 157 °C for about 5 minutes. TABLE 4

The composite nonwoven abrasive was then slit into 12.7 mm widths and fabricated into 457 mm long endless belts suitable for use on conventional abrasive fde belt sanders. In preparation for making a butt splice, the ends of the 12.7 mm wide strip were cut at an angle of approximately 30° from the perpendicular to the length of the belt. A butt belt splice was then made using a conventional polyurethane splicing adhesive and a heated belt splicing press. The 12.7 mm by 457 mm nonwoven abrasive composite belt of Example 1 was evaluated in comparison to Comparative Example. The belt was mounted on a portable, air-powered, hand-held platen sander (Model 28366, manufactured by 3M, 90 psi (0.62 MPa) inlet pressure 1/2 -inch (1.3 cm) ID air supply) which had a graphite platen extension arm (Model 28368, manufactured by 3M) that supported the belt when the belt was urged against a stainless steel workpiece. The belt was urged against a 12 mm thick 304 stainless steel plate edge with a force of about 8.9 newtons for 15 seconds. The belt of Example 1 did not show any obvious deterioration of the backside fabric portion of the belt.

EXAMPLE 2

The process of Example 1 was repeated, with the exception a plurality of sinusoidal stipes with an amplitude of 10 mm and a wavelength of 40 mm and a spacing between sinusoidal stripes of 13 mm was applied on the fabric backing side opposite the air laid nonwoven web using the mixture reported in Table 3 and the dry resin weight from the needle die was 208 g/m ² . The belt of Example 2 did not show any obvious visible deterioration of the backside fabric portion of the belt when tested.

EXAMPLE 3

The process of Example 2 was repeated, with the exception that the dry resin weight from the needle die was 58 g/m ^2, which gave an interrupted noncontinuous sinusoidal coating. The belt of Example 3 did not show any obvious deterioration of the backside fabric portion of the belt when tested.

COMPARATIVE EXAMPLE A

An air laid nonwoven web was formed using 192 grams per square meter (g/m ) FIB using a web forming machine, available as RANDO-WEBBER from the Rando Machine Corporation of Macedon, New York. The air laid fiber web was then placed upon a polyester greige sateen, heat set, de-stretched woven cloth which bad a basis weight of 260 g/m ² - and is available from Milliken, Inc., Spartanburg, South Carolina. The air laid web was then needled into and partially through the greige cloth. The needled composite was roll coated with the resin mixture reported in Table 2 and was then cured in an oven for about 5 minutes at 152 degrees Celsius (°C) to achieve a dsy resin weight of 205 g/m

An abrasive slurry mix was then applied at a wet weight of 628 g/m using spray coating to coat the air laid nonwoven web (opposite the woven cloth) using the mixture reported in Table 4. The abrasive slurry mix was then cured in an oven at 157 °C for about 5 minutes.

It was observed that the belt of Comparative Example A showed deterioration of the backside fabric portion of the belt when tested. All cited references, patents, and patent applications in this application are incorporated by reference in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in this application shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.