MULTIPLE LAYER ABRASIVE BACKERS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 63/730,652, filed Dec. 11, 2024, the complete disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

This description generally relates to abrasive backers and structures incorporating abrasive backers such as sanding papers, sanding discs and the like.

BACKGROUND

Abrasive backers for sanding applications typically comprise vulcanized fiber sheets formed from a cotton base that has been partially gelatinized by dissolving some of the cotton cellulose with an acid. These vulcanized fiber sheets are sometimes referred to as resin fiber sanding discs and may be used for sanding harder surfaces, such as metal and wood. While these vulcanized fiber sheets are generally tough and durable, they are also hydroscopic and absorb moisture (e.g., water) readily. Thus, when these sheets are made into a coated abrasive sheet, the surface opposite the grit coating can swell and/or contract, which causes the sheet to change shape with changes in relative humidity.

To avoid some of these drawbacks, abrasive backers have been developed that comprise a polymer-reinforced paper that includes one or more cellulose-based layers or plies that are laminated together. The cellulose fibers may include wood based pulps or other non-wood derived fiber sources. Synthetic fibers are used in conjunction with the cellulose fibers to increase the tear resistance of the fibrous web. The cellulose and synthetic fibers are immersed in a solvent and cured with, for example, a curable latex polymer to create a stronger form of the polymer material.

The cellulose-based plies of abrasive fibers typically include fibers that are unidirectional, i.e., substantially all of the fibers generally extend in the same direction. The direction that fibers are oriented is usually referred to as the machine direction (MD), or the direction that the material unwinds as it is being fed into a press, tunnel or any other device. The cross machine direction (CD) is typically used to refer to the direction at a right angle or 90 degrees from the MD. Thus, these abrasive backers are considered to be substantially anisotropic, wherein more of the fibers are aligned with each other in the MD than in the CD. This creates a structure that may have physical properties, such as tensile, tear and stretch, that are primarily dependent on the direction or orientation of the fibers.

SUMMARY

Abrasive backers and structures incorporating abrasive backers are provided herein. The structures may include abrasive papers, such as sandpaper, sanding discs, and the like. The abrasive backers include multiple layers or plies that are each formed of substantially unidirectional fibers. The layers are stacked in orientations relative to each other that provide at least partial isotropic properties to the backer, which improves the strength, strain and stiffness properties of the backer and the abrasive structure. In addition, this improves the MD/CD ratios of the backer for tensile strength, tear strength and stretch, which improves the directional properties of the material.

In one aspect, an abrasive backer comprises a first layer comprising cellulose fibers and a second layer in contact with the first layer and comprising cellulose fibers. The cellulose fibers in the first layer are substantially arranged in a first fiber orientation and the cellulose fibers in the second layer are substantially arranged in a second fiber orientation that differs from the first fiber orientation.

In various embodiments, the second fiber orientation differs from the first fiber orientation by about 1 degree to about 90 degrees. In certain embodiments, the second fiber orientation differs from the first fiber orientation by about 25 degrees, or about 45 degrees, or about 65 degrees or about 90 degrees.

In various embodiments, the abrasive backer may comprise more than two layers or at least 4 layers, or at least 6 layers, or 8 layers or more. The stacking sequence of the fiber orientations in each layer is preferably selected in a manner that results in the abrasive backer exhibiting at least partial isotropic properties and, in some embodiments, quasi-isotropic properties. Providing at least partial isotropic properties to the backer improves the strength, strain and stiffness properties of the backer. In addition, since the backer has more uniform properties in all directions, this reduces the heat buildup of the abrasive structure when it is rotated in a circular motion, such as occurs with a sanding disc.

In various embodiments, the abrasive backer comprises a third layer in contact with the second layer and comprising cellulose fibers. The cellulose fibers of the third layer are arranged in a third fiber orientation. The third fiber orientation may be parallel to the first fiber orientation, parallel to the second fiber orientation or transverse to both the first and second fiber orientations.

In various embodiments, the abrasive backer further comprises third and fourth layers comprising cellulose fibers. The fibers of the first and third layers are arranged in the first fiber orientation (i.e., substantially parallel to each other) and the fibers of the second and fourth layers are arranged in the second fiber orientation (i.e., substantially parallel to each other). In one such embodiment, the second layer is disposed between the first and third layers and the fourth layer is in contact with the third layer opposite the second layer. The second fiber orientation differs from the first fiber orientation by about 1 degree to about 90 degrees. In certain embodiments, the second fiber orientation differs from the first fiber orientation by about 90 degrees or by about 45 degrees.

In various embodiments, the abrasive backer comprises a fifth layer in contact with the first layer opposite the second layer. The fifth layer may extend in the first fiber orientation, the second fiber orientation or a third orientation transverse to the first and second fiber orientations.

In various embodiments, the plurality of layers further comprises a sixth layer in contact with the fourth layer opposite the third layer. The sixth layer may extend in the first fiber orientation, the second fiber orientation or a third orientation transverse to the first and second fiber orientations.

In various embodiments, the abrasive backer comprises an upper portion and a lower portion. The layers in the upper portion may be oriented in substantially the same direction and the layers in the lower portion may be oriented in substantially the same direction, transverse to the layers in the upper portion.

In various embodiments, the layers of the abrasive backer may alternate such that, for example, the first, third, fifth, etc. layers are oriented in substantially the same direction and the second, fourth, sixth, etc. layers are oriented in substantially the same direction, that differs from the orientation of the first, third and fifth layers.

In various embodiments, each of the layers in the abrasive backer may be oriented in different directions. Alternatively, the upper portion of the abrasive backer may be a mirror image of the lower portion, wherein the layers of the upper portion sequentially differ in orientation and the layers of the lower portion also sequentially differ in orientation with the reverse sequence as the upper portion.

In various embodiments, the abrasive backer has improved MD/CD ratios for tensile, stretch and tear strength, which improves the directional properties of the abrasive backer (i.e., the tensile, stretch and tear strengths are substantially the same in the MD/CD directions).

In embodiments, the abrasive backer has a MD/CD tensile ratio between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9 or about 1.05 or about 0.95 or about 1.

In various embodiments, the abrasive backer has a MD/CD stretch ratio of between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9.

In various embodiments, the abrasive backer has a MD/CD tear ratio of between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9 or about 1.05 or about 0.95 or about 1.

In various embodiments, the layers of the abrasive backer comprise a nonwoven web. The nonwoven web may comprise cellulose fibers and/or synthetic fibers. The layers may include a saturating composition.

Suitable cellulose fibers include, but are not limited to, wood based pulps or other non-wood derived fiber sources, such as softwoods, hardwoods straws and grasses, such as rice, esparto, wheat, rye and sabai; canes and reeds, such as bagasse and bamboos; woody stalks, such as jute, flax, kenaf and cannabis; bast, such as linen and ramic; leaves, such as abaca and sisal; seeds, such as cotton and cotton liners, and combinations thereof.

Suitable synthetic fibers include, but are not limited to, polyolefins, polytetrafluoroethylene, polyesters, polyvinyl acetate, polyvinyl chloride acetate polyvinyl butyral, acrylic resins, polyamides, polyvinyl chloride; polyvinylidene chloride; polystyrene:polyvinyl alcohol; polyurethanes; polylactic acid and combinations thereof.

The saturating composition may include, but is not limited to, a curable latex polymeric binder, a film forming resin and combinations thereof. Suitable latex polymers include, but are not limited to, polyacrylates including polymethacrylates, poly(acrylic acid), poly(methacrylic acid), and copolymers of the various acrylate and methacrylate esters and the free acids; styrene butadiene copolymers; ethylene-vinyl acetate copolymers; nitrile rubbers or acrylonitrile-butadiene copolymers; poly(vinyl chloride); poly(vinyl acetate); ethylene-acrylate copolymers; vinyl acetate-acrylate copolymers; neoprene rubbers or trans-1,4-polychloroprenes; cis-1,4-polyisoprenes; butadiene rubbers or cis- and trans-1,4-polybutadienes; ethylene-propylene copolymers, or mixtures thereof.

In another aspect, an abrasive structure is provided with one of the abrasive backers described above. The abrasive structure comprises an abrasive coating in contact with one of the layers of the backer. The abrasive coating may include a plurality of abrasive particles. The abrasive structure may comprise, for example, a sandpaper, a sanding disc or the like.

In another aspect, an abrasive backer comprises a plurality of layers in contact with each other, each of the plurality of layers comprising cellulose fibers. The plurality of layers are arranged in a fiber orientation sequence configured to provide the backer with at least partial isotropic properties. In certain embodiments, the fiber orientation sequence of the backer is quasi-isotropic.

In various embodiments, the abrasive backer has a MD/CD tensile ratio between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9 or about 1.05 or about 0.95 or about 1.

In various embodiments, the abrasive backer has a MD/CD stretch ratio of between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9.

In various embodiments, the abrasive backer has a MD/CD tear ratio of between about 1.5 to about 0.5, or about 1.25 to about 0.75, or about 1.1 to about 0.9 or about 1.05 or about 0.95 or about 1.

In various embodiments, the abrasive backer comprises 2 plies to about 20 plies, or about 4 plies to about 8 plies, laminated together.

In embodiments, the abrasive backer has a first plurality of layers oriented in a first direction and a second plurality of layers oriented in the second direction, wherein the first direction is oriented about 90 degrees relative to the second direction. In an exemplary embodiment, the first plurality of layers contains a substantially equal number of plies as the second plurality of layers. In this embodiment, the abrasive backer may have a MD/CD tensile ratio of about 1.1 to about 0.9 or about 1.05 or about 0.95 or about 1, a MD/CD stretch ratio of between about 1.1 to about 0.9 and a MD/CD tear ratio of between about 1.05 or about 0.95 or about 1.

In various embodiments, the abrasive backer comprises two or more sub-laminate layers. Each of the sub-laminate layers comprise two or more plies having substantially the same fiber orientation. This allows each of the sub-laminate layers to be laminated simultaneously, thereby increasing the yield of the manufacturing operation.

In one such embodiment, the abrasive backer comprises first and second sub-laminate layers each comprising at least two plies laminated together. The plies of the first sub-laminate layer are arranged in a first fiber orientation and the plies of the second sub-laminate layer are arranged in a second fiber orientation. The first fiber orientation differs from the second fiber orientation.

In various embodiments, the abrasive backer comprises third and fourth sub-laminate layers each comprising at least two plies laminated together. The plies of the third sub-laminate layer are arranged in a third fiber orientation and the plies of the fourth sub-laminate layer are arranged in a fourth fiber orientation. In one such embodiment, the third fiber orientation is substantially parallel to the first fiber orientation and the fourth fiber orientation is substantially parallel to the second fiber orientation. In another embodiment, the third fiber orientation is transverse to the first and the second fiber orientations and the fourth fiber orientation is transverse to the third fiber orientation.

In another aspect, an abrasive structure is provided with one of the abrasive backers described above. The abrasive structure comprises an abrasive coating in contact with one of the layers of the backer. The abrasive coating may include a plurality of abrasive particles. The abrasive structure may comprise, for example, a sandpaper, a sanding disc or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a cross-sectional view of an abrasive backer;

FIG. 2 is a cross-sectional view of an abrasive structure;

FIG. 3 is a schematic view of an abrasive backer with three ply sheets;

FIG. 4 is a schematic view illustrating an abrasive backer with one ply sheet oriented at a 45 degree angle relative to the other ply sheet;

FIG. 5 is a schematic view of an abrasive backer with five ply sheets;

FIG. 6 is a schematic view of an abrasive backer with six ply sheets;

FIG. 7 is a schematic view of an abrasive backer with six ply sheets and three sub-laminate layers;

FIG. 8 is a schematic view of an abrasive backer with eight ply sheets; and

FIG. 9 is a schematic view of an abrasive backer with eight ply sheets and four sub-laminate layers.

DESCRIPTION OF THE EMBODIMENTS

This description and the accompanying drawings illustrate exemplary embodiments and should not be taken as limiting, with the claims defining the scope of the present disclosure, including equivalents. Various mechanical, compositional, structural, and operational changes may be made without departing from the scope of this description and the claims, including equivalents. In some instances, well-known structures and techniques have not been shown or described in detail so as not to obscure the disclosure. Like numbers in two or more figures represent the same or similar elements. Furthermore, elements and their associated aspects that are described in detail with reference to one embodiment may, whenever practical, be included in other embodiments in which they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment and is not described with reference to a second embodiment, the element may nevertheless be claimed as included in the second embodiment. Moreover, the depictions herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated components.

It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

Abrasive backers and structures incorporating abrasive backers are provided herein. The structures may include abrasive papers, such as sanding papers, sanding discs, surface conditioning sanding discs, resin fiber sanding discs, PSA sanding discs, semi-flexible sanding discs and the like. In some embodiments, sanding discs are provided for use in sanding both metal and wood with grit in, for example, the range of P12 to P120, or about P 24 to about P80. The abrasive backers include multiple plies or sheets that are formed of substantially unidirectional fibers which are stacked in orientations that provide a controlled amount of mismatch of the Poisson's ratio of the adjacent plies. This results in an abrasive backer with at least partial isotropic properties, which improves the strength, strain and stiffness properties of the backer and/or the abrasive structure.

Referring now to FIG. 1, an abrasive backer 10 comprises first and second layers or ply sheets 20, 30 laminated together. Ply sheets 20, 30 may have an adhesive layer 40 therebetween. Each of the ply sheets 20, 30 comprise a plurality of fibers that are substantially oriented in one direction, i.e., unidirectional. In some embodiments (discussed below), the ply sheets are formed from a nonwoven web that includes cellulose fibers and/or synthetic fibers. In some embodiments, a top coating (not shown), such as a film forming coating, a barrier coating, a semiporous coating and the like, may be applied to an outer surface 22 of ply sheet 20 and a bottom coating (not shown) may be applied to an outer surface 32 of ply sheet 30. In other embodiments, an additional coating or coatings (not shown) can optionally be present on the top outer surface 22 of the backer 10 and/or the bottom outer surface 32 of the backer 10 to define the exposed surface. Thus, abrasive backer 10 can be further tailored depending on the desired end use of the sheet through additional coatings thereon.

The fibers in ply sheet 20 are substantially oriented in a different direction from the fibers in ply sheet 30. The direction that fibers are oriented may be considered the machine direction (MD), or the direction that the material unwinds as it is being fed into a press, tunnel or any other device. The cross machine direction (CD) is the direction at a right angle or 90 degrees from the MD. In particular, the fibers in ply sheet 20 may be oriented in a first direction or MD while the fibers in ply sheet 30 have an orientation in a second direction or MD of about 1 degree to about 90 degrees relative to the first direction. In some embodiments, the second direction is at least about 15 degrees, or at least about 25 degrees or at least about 45 degrees relative to the first direction. In certain embodiments, the second direction is 45 degrees relative to the first direction. In other embodiments, the second direction is 90 degrees relative to the first direction.

As discussed in more detail below, the number of ply sheets forming abrasive backer 10 may vary depending on the application. The stacking sequence of the ply orientations is preferably selected in a manner that results in backer 10 exhibiting at least partial isotropic properties and in some embodiments, quasi-isotropic properties. The term “isotropic” refers to properties of a material that are substantially identical in all directions. In contrast, the term “anisotropic” refers to properties of a material that are dependent upon the direction of an applied load. Individual ply sheets which include unidirectional fibers are substantially anisotropic in that the modulus of the ply is greater along the length of the fibers than the modulus in a direction transverse to the length of the fibers. In contrast to the anisotropic nature of the individual ply sheets 20, 30, the difference between the transverse and longitudinal modulus of backer 10 may be substantially reduced using a particular ply orientation stacking sequence. The selected stacking sequence renders the backer 10 less anisotropic and more nearly isotropic, a condition which is referred to herein as “quasi-isotropic”.

Providing at least partial isotropic properties to the backer improves the strength, strain and stiffness properties of the backer. For example, the isotropic properties reduces the MD/CD tensile ratio of backer. In certain embodiments, the MD/CD tensile ratio may be reduced by at least about 10%, or about 25% or at least about 30%. For example, in certain embodiments, the backer may have an MD/CD tensile ratio of less than about 1.5, or less than about 1.3 or about 1.1. The isotropic properties of the backer may also increase the stretch MD/CD ratio of the backer. In certain embodiments, the MD/CD stretch ratio may be increased by at least about 50% or at least about 75% or 100% or greater. For example, in certain embodiments, the MD/CD stretch ratio may be at least about 0.4, or at least about 0.75 or at least about 0.84. In addition, the abrasive backer will create out of plane disturbances of lower amplitude when the backer is part of an abrasive structure that is, for example, spun in a circular motion because the composite structure properties have been more equalized in the in-plane directions. This reduces the heat buildup of the abrasive structure during rotation at both high RPMs (e.g., 5,000 to 20,000) and low RPMs (e.g., 500 to 5000).

Ply sheets 20, 30 may comprise a saturated nonwoven web that includes cellulose fibers and a cured saturant composition. In certain embodiments, the ply sheets may also comprise synthetic fibers. The cellulosic material and the synthetic fibers are mixed together to form a fibrous mixture. The amount of synthetic fibers in the fibrous mixture can be controlled such that the resulting nonwoven web retains the paper properties of the cellulosic material with added strength from the synthetic fibers. For example, the fibrous mixture may contain about 4 wt % to about 20 wt % synthetic fibers (e.g., about 7 wt % to about 12 wt %) and about 80 wt % to about 96 wt % of cellulosic fibers (about 88 wt % to about 93 wt %), based on the dried weight of the resulting nonwoven web. Various additives may be applied to the cellulose fibers during formation of the fibrous web, including but not limited to, wet-strength agents, antifoaming agents, pigments, processing aids and dispersing agents. A more complete description of suitable processes for manufacturing the ply sheets herein can be found in US Patent Publication No. 2015/0306739, the complete disclosure of which is incorporated herein by reference for all purposes.

The cellulose fibers may comprise a material that contains wood based pulps or other non-wood derived fiber sources. The pulp may be a primary fibrous material or a secondary fibrous material (i.e., recycled). Suitable pulp fibers include, but are not limited to, softwoods, hardwoods straws and grasses, such as rice, esparto, wheat, rye and sabai; canes and reeds, such as bagasse and bamboos; woody stalks, such as jute, flax, kenaf and cannabis; bast, such as linen and ramic; leaves, such as abaca and sisal; seeds, such as cotton and cotton liners, and combinations thereof.

The synthetic fibers that may be used in conjunction with the cellulose fibers can be formed of any suitable material and to any suitable size and shape such that they serve as high tensile strength fibers. Suitable synthetic fibers include, but are not limited to, polyolefins (e.g., polyethylene, polypropylene, polybutylene and the like); polytetrafluoroethylene; polyesters (e.g., polyethylene terephthalate); polyvinyl acetate; polyvinyl chloride acetate; polyvinyl butyral; acrylic resins (e.g., polyacrylate, polymethacrylate, polymethylmethacrylate etc.); polyamides (e.g., nylon 6, nylon 6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, and nylon 12/12); polyvinyl chloride; polyvinylidene chloride; polystyrene:polyvinyl alcohol; polyurethanes; polylactic acid and combinations thereof.

In an exemplary embodiment, the synthetic fibers are polyester fibers that generally have an average length long enough to add strength to the nonwoven web while being short enough for paper processing of the web. Suitable average lengths for the synthetic fibers are about 0.25 inches to about 1.5 inches. The shape of the fibers may be any suitable shape, such as circular, elliptical, trilobal, flat or the like.

The saturating composition may include, but is not limited to, a curable latex polymeric binder, a film forming resin and combinations thereof. The latex polymer may be, for example, crosslinked upon curing to a suitable film forming resin, such as a styrene maleic anhydride copolymer. Alternatively, the latex polymer may be self-crosslinked with the aid of a suitable crosslinking agent. The saturant composition may include other components, such as antioxidants, particles, fillers, emulsifying agents, surfactants, chemicals for pH adjustments and the like. Suitable latex polymers include, but are not limited to, polyacrylates including polymethacrylates, poly(acrylic acid), poly(methacrylic acid), and copolymers of the various acrylate and methacrylate esters and the free acids; styrene butadiene copolymers; ethylene-vinyl acetate copolymers; nitrile rubbers or acrylonitrile-butadiene copolymers; poly(vinyl chloride); poly(vinyl acetate); ethylene-acrylate copolymers; vinyl acetate-acrylate copolymers; neoprene rubbers or trans-1,4-polychloroprenes; cis-1,4-polyisoprenes; butadiene rubbers or cis- and trans-1,4-polybutadienes; ethylene-propylene copolymers, or mixtures thereof. A more complete description of suitable saturating compositions can be found in previously incorporated US Patent Publication No. 2015/0306739.

The backer 100 may be manufactured by laminating ply sheets from roll goods to sheeted products in either 2-ply or 3-ply configurations. The produce is cut into square sheets with a typical size of about 36″×36″. This structure is termed a “sub-laminated” and the sub-laminates are then moved to a later processing step. The adhesive used for lamination can be a thermoset (hot-melt), water-based adhesive or a solvent based adhesive. In some embodiments, a portion (e.g., 30-50%) of the sheets of the sub-laminates may be cut on a guillotine trimmer at a 45 degree angle (shown in FIG. 4). A sheet to sheet laminator is then used to combine the sub-laminates together in either a one-pass or a two-pass process.

Referring now to FIG. 2, an abrasive structure 100 comprises first and second layers or ply sheets 20, 30 laminated together. Ply sheets 20, 30 may have an adhesive layer 40 therebetween. Each of the ply sheets 20, 30 comprise a plurality of fibers that are substantially oriented in one direction, e.g. unidirectional. As in the previous embodiment, the fibers in ply sheet 20 are substantially oriented in a different direction from the fibers in ply sheet 30 to create a more isotropic structure. In some embodiments (discussed below), the ply sheets are formed from a nonwoven web that includes cellulose fibers and/or synthetic fibers.

Structure 100 further includes a backside coating 60 that defines a backside surface 62 of structure 100 and an abrasive coating 50 that has an abrasive surface 52 for use in, for example, sandpaper, a sanding disc or the like. Backside coating 60 may include any suitable layer or coating on ply sheet 30 that is not configured to have a layer of abrasive particles thereon. Abrasive coating 50 may include abrasive particles 54 within the coating. To attach the abrasive particles to the coated surface of the abrasive backing, an adhesive is applied to the smooth, coated surface of the abrasive backing. Any of the known types of adhesives can be used to bond the abrasive particles to ply sheet 20.

Referring now to FIG. 3, another embodiment of an abrasive backer 200 comprises first, second and third ply sheets 202, 204, 206. In this embodiment, the fibers of the first and third ply sheets 202, 206 are oriented in the substantially the same direction and the fibers in the second ply sheet 204 are oriented in a direction transverse to the direction of sheets 202, 206. In an exemplary embodiment, second ply sheet 204 is oriented in a substantially perpendicular direction to sheets 202, 206. For example purposes only, first and third sheets 202, 206 may have an MD in the direction of arrow 210 and a CD in the direction of arrow 212. Similarly, second sheet 204 may have an MD in the direction of arrow 214 and a CD in the direction of arrow 216.

Referring now to FIG. 4, in some embodiments, at least one of the ply sheets may be oriented at a 45 degrees angle to at least one of the other ply sheets. As shown, an abrasive backer 250 comprises a first ply sheet 252 having an MD in the direction of arrow 260 and a CD in the direction of arrow 262. Backer 250 includes at least one other ply sheet 254 having an MD and a CD at a 45 degree angle to the MD of ply sheet 252. In certain embodiments, ply sheet 254 may be slightly smaller than ply sheet 252, resulting in a slight loss in yield due to the change in orientation.

Referring now to FIG. 5, another embodiment of an abrasive backer 300 comprises at least five ply sheets 302, 304, 306, 308, 310, although it will be recognized that backer 300 may have less than, or more than, five ply sheets. In this embodiment, the ply sheets are oriented so that the MDs and CDs alternate between each individual ply sheet. Thus, ply sheets 302, 306 and 310 have an MD in the direction of arrow 320 and a CD in the direction of arrow 330. Ply sheets 304, 308 are oriented at transverse angle to sheets 302, 306, 310. In an exemplary embodiment, this angle is 90 degrees such that ply sheets 304, 308 each have an MD in the direction of arrow 322 and a CD in the direction of arrow 332, although it will be recognized that ply sheets 304, 308 may be oriented at other angles, such as the 45 degree angle shown in FIG. 4. In addition, it should be recognized that ply sheets 304, 308 may be oriented at different angles from each other. For example, ply sheet 304 may be oriented at a 90 degree angle while ply sheet 308 is oriented at other transverse angles, e.g., 25 degrees, 45 degrees and the like.

Referring now to FIG. 6, another embodiment of an abrasive backer 400 comprises at least six ply sheets 402, 404, 406, 408, 410, 412, although it will be recognized that backer 400 may have less than, or more than, six ply sheets. In this embodiment, the ply sheets are oriented so that the lower ply sheets are oriented in a different direction than the upper ply sheets. This allows, for example, the upper ply sheets (and/or the lower ply sheets) to be laminated simultaneously, which optimizes the yield of the laminating operation. Thus, ply sheets 412, 410, 408 have an MD in the direction of arrow 420 and a CD in the direction of arrow 430. Ply sheets 406, 404, 402 are oriented at transverse angle to sheets 408, 410, 412. In an exemplary embodiment, this angle is 90 degrees such that ply sheets 402, 404, 406 each have an MD in the direction of arrow 422 and a CD in the direction of arrow 432 and ply sheets 408, 410, 412 each have an MD in the direction of arrow 420 and a CD in the direction of arrow 430, although it will be recognized that ply sheets 402, 404, 406 and/or sheets 408, 410, 412 may be oriented at other angles, such as the 45 degree angle shown in FIG. 4. In addition, it should be recognized that ply sheets 402, 404, 406 and/or ply sheets 408, 410, 412 may be oriented at different angles from each other. For example, ply sheet 406 may be oriented at a 90 degree angle while ply sheets 404 and/or 402 are oriented at other transverse angles, e.g., 25 degrees, 45 degrees and the like.

Referring now to FIG. 7, another embodiment of an abrasive backer 500 comprises at least six ply sheets 508, 510, 512, 514, 516 and 518, although it will be recognized that backer 500 may have less than, or more than, six ply sheets. In this embodiment, backer 500 includes sub-laminate layers 502, 504, 506 that include 2 or more individual ply sheets that are oriented in the same direction as each other. This allows each of the sub-laminate layers to be laminated simultaneously, thereby increasing the yield of the manufacturing operation. Thus, for example, sub-laminate layer 502 includes ply sheets 508, 510 having a MD in the direction of arrow 520 and a CD in the direction of arrow 522. In certain embodiments, the ply sheets of sub-laminate layers 504, 506 have fiber orientations that are transverse to the ply sheets of layer 502. These fiber orientations may have any of the above configurations, i.e., alternating between each sub-laminate layer or lower sub-laminate layers having a different orientation that higher sub-laminate layers. In addition, the angle of these orientations may vary from 1 degrees to 90 degrees.

In the exemplary embodiment, layer 504 includes two ply sheets 512, 514 having MD and CD directions oriented at a 45 degree angle to layer 502. Layer 506 includes two ply sheets 516, 518 having MD and CD directions oriented at a 45 degree angle to layer 504 and a 90 degree angle to layer 506. Thus, layer 506 may have a MD in the direction of arrow 530 and a CD in the direction of arrow 532. The 45 degree sub-laminate layer 504 increases the overall isotropic properties of the backer.

Referring now to FIG. 8, another embodiment of an abrasive backer 600 comprises 8 ply sheets 602, 604, 606, 608, 610, 612, 614, 616, although it will be recognized that backer 600 may have less than, or more than, 8 ply sheets. In this embodiment, the upper portion of backer 600 includes ply sheets that alternate from one ply sheet to another and the lower portion of backer 600 is generally the reverse or mirror image of the upper portion.

In an exemplary embodiment, ply sheet 602 has a MD in the direction of arrow 620 and a CD in the direction of arrow 622. Ply sheet 604 is oriented at a 90 degree angle to ply sheet 602. Ply sheet 606 is oriented at a 45 degree angle to ply sheet 604. Ply sheet 608 is oriented at a 90 degree angle to ply sheet 606 and at a 90 degree angle to ply sheet 604. Ply sheet 610 may be oriented at the same angle as ply sheet 608. Similarly, ply sheet 612 is oriented at the same angle as ply sheet 606, ply sheet 614 is oriented at the same angle as ply sheet 604 and ply sheet 616 is oriented at the same angle as ply sheet 602. Thus, the lower portion of backer 600 is a mirror image of the upper portion.

Referring now to FIG. 9, another embodiment of an abrasive backer 700 will now be described. In this embodiment, backer 700 includes sub-laminate layers 702, 704, 706, 708 that each include 2 or more individual ply sheets that are oriented in the same direction as each other. Thus, layer 702 includes ply sheets 710, 712 that have a MD in the direction of arrow 730 and a CD in the direction of arrow 732. Each of the remaining layers may have orientations that are transverse to layer 702. Alternatively, some of the remaining layers may have the same orientation as layer 702.

In an exemplary embodiment, layer 704 includes 2 ply sheets 714, 76 that each have an orientation that is 45 degrees relative to the orientation of layer 702. Layer 706 includes 2 ply sheets 718, 720 that each have an orientation that is 45 degrees relative to layer 704 and 90 degrees relative to layer 702. Layer 708 includes two ply sheets 722, 274 that each have the same orientation as layer 702.

In the following Examples, the test labs were maintained at TAPPI Standard Conditions (T402). Applicant conducted testing according to the following TAPPI Standards: (1) basis weight was measured according to TAPPI T410; (2) caliper was measured according to TAPPI T4111; (3) Sheffield porosity was measured according to TAPPI T536; (5) stretch was measured according to TAPPI T494; (6) tear was measured according to TAPPI T414; and (7) tensile was measured according to TAPPI T494.

Example 1

Applicant conducted testing of two different abrasive backers: (1) a 5-ply backer wherein all of the fibers were aligned in the same direction, i.e., anisotropic (labeled ALL MD); and (2) a 5-ply backer wherein the fibers were orientated in different directions as described above to create a more isotropic product (labeled MD/CD Alt, i.e., the MD and CD directions of each ply sheet alternate in each successive ply sheet). The backers were manufactured as described above (saturated, calendared and then aged). The result of this testing is shown below in TABLE 1.

	TABLE 1
	ALL MD	MD/CD Alt

Basis Weight (1298 ft2)	144.92	145.49
Basis Weight (gsm)	544.90	457.04
Caliper (mil)	28.94	29.41
Caliper (mm)	0.7351	0.7470
Tensile MD (lb./15 mm)	51.51	39.11
Tensile CD (lb./15 mm)	3291	35.62
Tensile MD/CD	1.565	1.098
RMS Tensile (lb./15 mm)	61.13	52.90
Stretch MD (percentage)	4.53	4.99
Stretch, CD (percentage)	11.51	594
Stretch MD/CD	0.394	0.840
Tear MD (grams force)	808	885
Tear CD (grams force)	772	844
Aged Wet Tensile MD (lb./15 mm)	26.12	17.02
Aged Wet Stretch MD (lb./15 mm)	9.09	14.22
Delamination MD (grams)	254	470
Wet Delamination MD, 1 hour (grams)	386	385
Wet Delamination MD, 24 hours (grams)	131	256
Sheffield Porosity	0.10	0.14
Curl	2.9	2.1

As shown in Table 1, the Tensile MD/CD ratio improved from 1.586 to 1.098 in the isotropic backer as compared to the anisotropic backer (a 29.8% improvement). In addition, the Stretch MD/CD ratio improved from 0.394 to 0.840 (a 113.4% improvement). In addition, the Tear MD increased from 808 to 885 and the Tear CD increased from 772 to 844. This testing was based on 1-ply (average of 16 tears or 4/sheet). The Aged Wet Tensile and Stretch MD were measured after soaking the backer for 20 minutes. The Aged Wet Tensile MD decreased from 26.12 to 17.02 and the Aged Wet Stretch MD increased from 9.09 to 14.22.

The delamination MD also improved with the isotropic backer. As shown in Table 1, the initial delamination MD increased from 254 to 270. After soaking the backers for 1 hour in cold city water, the wet delamination was about the same. After soaking the backers for 24 hours in the cold city water, the wet delamination MD improved from 131 to 256.

The porosity of the backers was measured using the Sheffield Porosity test to measure the flow rate of air through a single sheet. The samples were placed into rubber clamping rings and compressed air was passed through a flow measuring device and then directed to the samples. Air that passed through the samples escapes into the atmosphere through holes in the downstream clamping plate and the air flow was measured to determine the air permeance of the samples. As shown, the Sheffield Porosity improved with the isotropic backer from 0.10 to 0.14

One common defect with laminated webs is curl, or the inability of the web to lie flat under no tension. Curl originals from residual stresses in the laminate, often resulting from strain incompatibilities between the laminate. Applicant measure the curl in centimeters as the average tallest curl of the four sheets. The curl reduced from 2.9 cm to 2.1 cm in the isotropic backer.

Example 2

Applicant conducted testing of three different abrasive backers: (1): a 6-ply backer wherein the lower (or upper depending on orientation) three plies were oriented in the MD direction and the upper (or lower depending on orientation) three plies were oriented in the CD direction (labeled 3MD/3CD); and (2) a 6-ply backer with an upper layer, middle layer and a lower layer. The upper layer comprised two adjacent plies oriented in the MD direction, the middle layer comprised two adjacent plies oriented in the CD direction and the lower layer comprised two adjacent plies oriented in the MD direction (labeled 2MD/2CD/2MD); and (3) a 6-ply backer with an upper layer, middle layer and a lower layer. The upper layer comprised two adjacent plies oriented in the CD direction, the middle layer comprised two adjacent plies oriented at a 45 degree angle to the MD and CD directions and the lower layer comprised two adjacent plies oriented in the CD direction (labeled 2MD/2 45/2CD). Sample 1 represents a substantially isotropic material since the number of MD plies were equal to the number of CD plies, whereas Sample 2 included 4 MD plies and only 2 CD plies and Sample 3 includes 2 plies oriented at a 45 degree angle.

The backers were manufactured as described above (saturated, calendared and then aged). The result of this testing is shown below in TABLE 2.

TABLE 2
			2MDD/2
Basis Weight (1298 ft2)	3MD/3CD	2MD/2CD/2MD	45/2CD

Basis Weight (gsm)	274	263	289
Caliper (mil)	49.36	46.67	48.85
Caliper (mm)	1253.744	1185.418	1240.79
Tensile MD (lb./15 mm)	62.53	72.07	58.32
Tensile CD (lb./15 mm)	62.47	57.22	60.08
Tensile MD/CD Ratio	1.001	1.260	0.972
RMS Tensile (lb./15 mm)	88.39	92.02	83.73
Stretch MD (percentage)	9.14	7.8	10.93
Stretch, CD (percentage)	8.30	10.44	9.27
Stretch MD/CD Ratio	1.10	0.75	1.18
Tear MD (grams force)	1244	1640	1421
Tear CD (grams force)	1436	1180	1902
Tear MD/CD Ratio	0.87	1.39	0.75
Aged Wet Tensile MD	45.23	56.17	45.77
(lb./15 mm)
Aged Wet Stretch MD	8.49	10.45	12.42
(lb./15 mm)
Delamination MD (grams)	661	1010	719
Wet Delamination MD,	357	796	391
1 hour (grams)
Wet Delamination MD,	136	19	195
24 hours (grams)
Sheffield Porosity	0.16	0.15	0.17
Curl	0.77	0.43	0.87

As shown in Table 2, the Tensile MD/CD ratio was improved over the anisotropic backer in Table 1 in all three samples. Additionally, Sample 1 (3MD/3CD) demonstrated the best tensile MD/CD ratio of all three samples (1.001 versus 1.260 and 0.971). In addition, the Stretch MD/CD ratio improved over the anisotropic backer in Table 1 in all three samples. In addition, Sample 1 (3MD/3CD) demonstrated the best stretch MD/CD ratio of all three samples (1.10 versus 0.75 and 1.18). In addition, the Tear MD/CD ratio of Sample 1 was superior over the other two samples (0.87 versus 1.39 and 0.75). This testing was based on 1-ply (average of 16 tears or 4/sheet).

Thus, it was demonstrated that the substantially isotropic material (Sample 1) had superior tensile MD/CD ratios, stretch MD/CD ratios and tear MD/CD ratios. In particular, it is noted that the tensile MD/CD ratio was equal to 1.001, meaning that the MD tensile and CD tensile strengths were almost exactly identical to each other.

The Aged Wet Tensile and Stretch MD were measured after soaking the backer for 20 minutes. The Aged Wet Tensile MD of Sample 1 was less than Samples 2 and 3 (45.23 versus 56.17 and 45.77, respectively) and the Aged Wet Stretch MD of Sample 1 was less than Samples 2 and 3 (8.49 versus 10.45 and 12.42, respectively.

The delamination MD also improved with the isotropic backer of Sample 1. As shown in Table 2, the initial delamination MD increased from 254 to 270. After soaking the backers for 1 hour in cold city water, the wet delamination was about the same. After soaking the backers for 24 hours in the cold city water, the wet delamination MD improved from 131 to 256.

The porosity of the backers was measured using the Sheffield Porosity test to measure the flow rate of air through a single sheet. The samples were placed into rubber clamping rings and compressed air was passed through a flow measuring device and then directed to the samples. Air that passed through the samples escapes into the atmosphere through holes in the downstream clamping plate and the air flow was measured to determine the air permeance of the samples. As shown, the Sheffield Porosity improved with the isotropic backer from 0.10 to 0.14

One common defect with laminated webs is curl, or the inability of the web to lie flat under no tension. Curl originals from residual stresses in the laminate, often resulting from strain incompatibilities between the laminate. Applicant measured the curl in centimeters as the average tallest curl of the four sheets. The curl reduced was less than the anisotropic backer in all three samples (i.e., 0.77, 0.43 and 0.87 compared to 2.9).

Example 3

Applicant conducted additional testing of five different abrasive backers that all had the same configuration: the lower (or upper depending on orientation) three plies were oriented in the MD direction and the upper (or lower depending on orientation) three plies were oriented in the CD direction (similar to Sample 1 labeled 3MD/3CD in Example 2). These samples represent a substantially isotropic material since the number of MD plies were equal to the number of CD plies. The backers were manufactured as described above (saturated, calendared and then aged). The result of this testing is shown below in TABLE 3.

	TABLE 3
	SAMPLE	SAMPLE	SAMPLE	SAMPLE	SAMPLE
	1	2	3	4	5	Average	Std. Dev.

Basis Weight	235	234	232	234	233	233.55	1.05
(1298 ft2)
Basis Weight	883,45	878.49	873.52	880.14	875.18	878.16	3.95
(gsm)
Caliper (mil)	41.85	42.54	41.18	41.89	42.12	41.92	0.49
Caliper (mm)	1062.99	1080.516	1045.972	1064.006	1069.848	1064.67	12.56
Tensile MD	60.98	61.06	61.72	58.99	55.96	59.74	2.35
(lb./15 mm)
Tensile CD	59.58	59.71	59.67	60.89	56.11	59.19	1.8
(lb./15 mm)
Tensile	1.023	1.023	1.034	0.969	0.997	1.01	0.03
MD/CD
Ratio
RMS Tensile	85.25	85.40	85.85	84.78	79.25	84.11	2.74
(lb./15 mm)
Stretch MD	9.7	9.66	9.85	8.73	10.19	9.63	0.54
(percentage)
Stretch, CD	8.3	9.69	9.38	9.13	9.81	9.26	0.60
(percentage)
Stretch	1.17	1.00	1.05	0.96	1.04	1.04	0.08
MD/CD
Ratio
Tear MD	1504	1497.6	1491.2	1507.2	1459.2	1491.84	19.25
(grams force)
Tear CD	1465.6	1497.6	1452.8	1507.2	1532.8	1491.2	32.24
(grams force)
Tear MD/CD	1.03	1.00	1.03	1.00	0.95	1.00	0.03
Ratio
Aged Wet	40.69	36.24	36.91	34	30.17	35.60	3.88
Tensile MD
(lb./15 mm)
Aged Wet	12.98	13.34	12.73	12.91	12.07	12.81	0.47
Stretch MD
(lb./15 mm)
Delamination	862	836	721	679	704	760.40	82.76
MD (grams)
Wet	512	669	447	600	468	539.2	93.35
Delamination
MD, 1 hour
(grams)
Sheffield	0.12	0.12	0.09	0.09	0.1	0.10	0.02
Porosity
Curl	0.5	0.5	0.5	0.6	1	0.62	0.22

As shown in Table 3, the Tensile MD/CD ratio was improved over the anisotropic backer in Table 1 in all five samples. The average tensile MD/CD ratio was 1.01 with a standard deviation of 0.03. In addition, the Stretch MD/CD ratio improved over the anisotropic backer in Table 1 in all five samples. The average stretch MD/CD ratio was 1.04 with a standard deviation of 0.08. In addition, the tear MD/CD ratio improved over the anisotropic backer in Table 1 in all give samples. The average tear MD/CD ratio was 1.00 with a standard deviation of 0.03. This testing was based on 1-ply (average of 16 tears or 4/sheet).

Thus, it was further demonstrated that the substantially isotropic material had superior tensile MD/CD ratios, stretch MD/CD ratios and tear MD/CD ratios. In particular, it is noted that the average tensile MD/CD ratio was equal to 1.01, the average stretch MD/CD ratio was equal to 1.04 and the average tear MD/CD ratio was equal to 1.00, meaning that these values were almost exactly equal in the MD/CD directions (i.e., almost completely isotropic).

The Aged Wet Tensile and Stretch MD were measured after soaking the backer for 20 minutes. The porosity of the backers was measured using the Sheffield Porosity test to measure the flow rate of air through a single sheet. The samples were placed into rubber clamping rings and compressed air was passed through a flow measuring device and then directed to the samples. Air that passed through the samples escapes into the atmosphere through holes in the downstream clamping plate and the air flow was measured to determine the air permeance of the samples. As shown, the Sheffield Porosity improved with the isotropic backer from 0.10 to 0.14

Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the embodiment disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the embodiment being indicated by the following claims.

For example, in a first aspect, a first embodiment is an abrasive backer comprising a first layer comprising cellulose fibers and a second layer in contact with the first layer and comprising cellulose fibers. The cellulose fibers in the first layer are substantially arranged in a first fiber orientation and the cellulose fibers in the second layer are substantially arranged in a second fiber orientation. The first fiber orientation differs from the second fiber orientation.

A second embodiment is the first embodiment, wherein the second fiber orientation differs from the first fiber orientation by about 1 degree to about 90 degrees.

A 3rd embodiment is any combination of the first 2 embodiments, wherein the second fiber orientation differs from the first fiber orientation by about 90 degrees.

A 4th embodiment is any combination of the first 3 embodiments, wherein the second fiber orientation differs from the first fiber orientation by about 45 degrees.

A 5th embodiment is any combination of the first 4 embodiments, further comprising a third layer in contact with the second layer and comprising cellulose fibers, wherein the cellulose fibers of the third layer are arranged in a third fiber orientation.

A 6th embodiment is any combination of the first 5 embodiments, wherein the third fiber orientation is parallel to the first fiber orientation.

A 7th embodiment is any combination of the first 6 embodiments, wherein the third fiber orientation is parallel to the second fiber orientation.

An 8th embodiment is any combination of the first 7 embodiments, wherein the third fiber orientation is transverse to the first fiber orientation and the second fiber orientation.

A 9th embodiment is any combination of the first 8 embodiments, further comprising third and fourth layers comprising cellulose fibers, wherein the fibers of the first and third layers are arranged in the first fiber orientation and the fibers of the second and fourth layers are arranged in the second fiber orientation

A 10th embodiment is any combination of the first 9 embodiments, wherein the second layer is disposed between the first and third layers and the fourth layer is in contact with the third layer opposite the second layer.

An 11th embodiment is any combination of the first 10 embodiments, wherein the second fiber orientation differs from the first fiber orientation by about 90 degrees.

A 12th embodiment is any combination of the first 11 embodiments, wherein the plurality of layers further comprises a fifth layer in contact with the first layer opposite the second layer, wherein the fifth layer extends in the first fiber orientation.

A 13th embodiment is any combination of the first 12 embodiments, wherein the plurality of layers further comprises a sixth layer in contact with the fourth layer opposite the third layer, wherein the sixth layer extends in the second fiber orientation.

A 14th embodiment is any combination of the first 13 embodiments, wherein the fibers of the first and second layers are arranged in the first fiber orientation and the fibers of the third and fourth layers are arranged in the second fiber orientation.

A 15th embodiment is any combination of the first 14 embodiments, wherein the first fiber orientation differs from the second fiber orientation by about 90 degrees.

A 16th embodiment is any combination of the first 15 embodiments, wherein the first fiber orientation differs from the second fiber orientation by about 45 degrees.

A 17th embodiment is any combination of the first 16 embodiments, wherein the first and second layers comprise a nonwoven web.

An 18th embodiment is any combination of the first 17 embodiments, wherein the first and second layers each comprise a saturating composition.

A 19th embodiment is any combination of the first 18 embodiments, wherein the saturating composition comprises a curable latex polymer.

A 20th embodiment is any combination of the first 19 embodiments, wherein the first and second layers further comprise synthetic fibers.

A 21st embodiment is any combination of the first 20 embodiments, wherein the synthetic fibers comprises a material selected from the group consisting of polyolefin, polytetrafluoroethylene, polyester, polyvinyl acetate, polyvinyl chloride acetate; polyvinyl butyral, acrylic resin, polyamides, polyvinyl chloride; polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyurethane, polylactic acid and combinations thereof.

A 22nd embodiment is any combination of the first 21 embodiments, further comprising an abrasive coating in contact with the first layer opposite the second layer.

A 23rd embodiment is any combination of the first 22 embodiments, wherein the cellulose fibers comprises hardwood fibers.

A 24th embodiment is any combination of the first 23 embodiments, wherein the abrasive structure has a MD/CD tensile ratio of less than about 1.5.

A 25th embodiment is any combination of the first 24 embodiments, wherein the MD/CD ratio is about 1.1 or less.

A 26th embodiment is any combination of the first 25 embodiments, wherein the first and second layers comprise plies that are laminated together.

In another aspect, an abrasive structure is provided comprising the abrasive backer of any combination of the first 26 embodiments, wherein the abrasive structure comprises a layer of abrasive particles in contact with one of the first and second layers of the abrasive backer.

In another aspect, a sandpaper is providing comprising the abrasive backer of any combination of the first 27 embodiments.

In another aspect, a sanding disc is providing comprising the abrasive backer of any combination of the first 27 embodiments.

In another aspect, a first embodiment is an abrasive backer comprising a plurality of layers in contact with each other, each of the plurality of layers comprising cellulose fibers. The plurality of layers are arranged in a fiber orientation sequence providing the backer with at least partial isotropic properties.

A second embodiment is the first embodiment, wherein the fiber orientation sequence of the backer is quasi-isotropic.

A third embodiment is any combination of the first 2 embodiments, wherein the abrasive backer has a MD/CD tensile ratio of less than about 1.5.

A 4th embodiment is any combination of the first 3 embodiments, wherein the MD/CD ratio is about 1.1 or less.

A 5th embodiment is any combination of the first 4 embodiments, wherein the abrasive backer has a MD/CD stretch ratio of greater than about 0.4.

A 6th embodiment is any combination of the first 5 embodiments, wherein the MD/CD stretch ratio is at least about 0.8.

A 7th embodiment is any combination of the first 6 embodiments, wherein the backer comprises 2 plies to about 20 plies, wherein the plies are laminated together.

An 8th embodiment is any combination of the first 7 embodiments, wherein the backer comprises about 4 plies to about 8 plies.

A 9th embodiment is any combination of the first 8 embodiments, further comprising first and second sub-laminate layers each comprising at least two plies laminated together, wherein the plies of the first sub-laminate layer are arranged in a first fiber orientation and the plies of the second sub-laminate layer are arranged in a second fiber orientation, wherein the first fiber orientation is transverse to the second fiber orientation.

A 10th embodiment is any combination of the first 9 embodiments, further comprising third and fourth sub-laminate layers each comprising at least two plies laminated together, wherein the plies of the third sub-laminate layer are arranged in a third fiber orientation and the plies of the fourth sub-laminate layer are arranged in a fourth fiber orientation.

An 11th embodiment is any combination of the first 10 embodiments, wherein the third fiber orientation is substantially parallel to the first fiber orientation and the fourth fiber orientation is substantially parallel to the second fiber orientation.

A 12th embodiment is any combination of the first 11 embodiments, wherein the third fiber orientation is transverse to the first and the second fiber orientations and the fourth fiber orientation is transverse to the third fiber orientation.

A 13th embodiment is any combination of the first 12 embodiments, wherein each of the plurality of layers comprise a nonwoven web.

A 14th embodiment is any combination of the first 13 embodiments, wherein each of the plurality of layers comprise a saturating composition.

A 15th embodiment is any combination of the first 14 embodiments, wherein the saturating composition comprises a curable latex polymer.

A 16th embodiment is any combination of the first 15 embodiments, wherein each of the plurality of layers further comprise synthetic fibers.

A 17th embodiment is any combination of the first 16 embodiments, wherein the synthetic fibers comprises a material selected from the group consisting of polyolefin, polytetrafluoroethylene, polyester, polyvinyl acetate, polyvinyl chloride acetate; polyvinyl butyral, acrylic resin, polyamides, polyvinyl chloride; polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyurethane, polylactic acid and combinations thereof.

In another aspect, an abrasive structure is provided comprising the abrasive backer of any combination of the first 17 embodiments, wherein the abrasive structure comprising an abrasive coating in contact with one of the plurality of layers.

In another aspect, a sand paper is provided comprising the abrasive backer of any combination of the first 18 embodiments.

In another aspect, a sanding disc is provided comprising the abrasive backer of any combination of the first 18 embodiments.