US20110159794A1

Movatterモバイル変換

Info

Publication number: US20110159794A1
Application number: US12/980,174
Authority: US
Inventors: Mervyn Chung-Fat; Virginie Vaubert; Sergio Rodrigues
Original assignee: Saint Gobain Abrasifs SA; Saint Gobain Abrasives Inc
Current assignee: Saint Gobain Abrasifs SA; Saint Gobain Abrasives Inc
Priority date: 2009-12-29
Filing date: 2010-12-28
Publication date: 2011-06-30
Also published as: WO2011080569A2; FR2954723B1; DE112010005029T5; WO2011080569A4; WO2011080569A3; DE112010005029B4; CA2785429A1; FR2954723A1

Abstract

An abrasive article includes a fabric comprising a front face and a back face. The front face is formed of first knitted yarns. Each yarn of the first knitted yarns includes a plurality of filaments. A plurality of threads intertwines with the first knitted yarns and extending between the front face and the back face. The plurality of threads defines a hollow space between the front face and the back face. The abrasive article also includes abrasive grains adhered to the front face of the fabric.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority from French Patent Application No. 09 06380, filed Dec. 29, 2009, entitled “ABRASIVE ARTICLE WITH OPEN STRUCTURE,” naming inventors Mervyn Chung-Fat, Virginie Vaubert and Sergio Rodrigues, which application is incorporated by reference herein in its entirety.

FIELD OF THE DISCLOSURE

This disclosure, in general, relates to abrasive articles with flexible open structures and to methods for making and using same.

BACKGROUND

Abrading is used in a variety of industries to affect surface properties of a material. For example, abrading is used in industries as diverse as electronic manufacturing, automotive painting, or even furniture manufacturing. In each of these industries, abrasive materials are selected based on material removal rate and the properties imparted to the final surface, but there is often a trade off between material removal rate and surface properties.

One difficulty associated with the abrading process is the removal of swarf or waste material abraded from the surface of a work piece being abraded. Particularly in dry abrasive processes, dust composed of waste material abraded from the surface of a work piece and grains and other material detached from the abrasive article become a problem. The dust, for example, can lodge between the abrasive article and the work piece, influencing surface quality and material removal rates. In particular, particles of hard material, such as cleaved abrasive grains, can lodge between the abrasive article and the work piece, causing scratching on the surface of the work piece. In another example, softer particles and dust can gather between the abrasive article and the work piece, resulting in less contact between the abrasive article and the work piece, reducing the material removal rate. In either case, the abraded waste material can result in a reduced surface quality and performance of the abrasive article.

As such, an improved abrasive article would be desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

FIG. 1 includes an illustration of an exemplary abrasive system.

FIG. 2 andFIG. 3 include illustrations of an exemplary abrasive article.

The use of the same reference symbols in different drawings indicates similar or identical items.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In a particular embodiment, an abrasive article includes a backing having a front face and a back face and adhesive grains adhered to the front face of the backing. In an example, the backing includes a fabric. The front face of the backing is formed of knitted yarns of the fabric. Each yarn of the knitted yarns includes a plurality of filaments. In addition, the fabric can include a plurality of threads intertwined with the knitted yarns and extending between the front face and the back face of the backing. The threads are a single fiber element and can be thicker than the filaments of the yarn. The plurality of threads defines a hollow space between the front face and the back face of the backing. Further, the knitted yarns can form a set of openings or aveoli that permit the flow of waste material and air from the front face of the backing into the hollow space between the front and back face of the backing. In an example, the abrasive grains are adhered to the front face of the backing using a binder that forms a continuous coating over the front face of the backing except over the aveoli.

In an additional embodiment, an abrasive article can be formed by dispensing a fabric including a front face and a back face, applying a binder formulation to the front face of the fabric, and applying abrasive grains to the front face of the fabric. The front face of the fabric is formed of knitted yarns. Each yarn of the knitted yarns includes a plurality of filaments. A plurality of threads is intertwined with the knitted yarns and extends between the front face and the back face. The threads define a hollow space between the front face and the back face. In an example, applying the binder formulation includes calendaring the binder formulation to the front face and the applying the abrasive grains includes depositing the abrasive grains by electrostatic deposition. In another example, the binder formulation and abrasive grains can be mixed and applied together in a slurry.

In use, the abrasive article can be coupled to an abrading device that repetitively moves the abrasive article parallel to a plane. The front face of the abrasive article is contacted with a surface of an article to be abraded and waste material is drawn from the front face of the work piece to the back face through a hollow space defined by the threads and the aveoli defined by the knitted yarns.

FIG. 1 includes an illustration of anexemplary abrading system100. Theabrading system100 includes anabrading device102 and anabrasive article104. In an example, theabrading device102 moves the abrasive article in a motion relative to a plane, such as a plane defined by the major surface of theabrasive article104. The motion of theabrasive device102 can be a circular motion or can be an oscillating motion. In particular, theabrasive article104 includes abacking106 having afront face124 and aback face126. To thefront face124 of thebacking106, a binder coating108 adheresabrasive grains110.

On theopposite surface126, thefabric106 is coupled to theabrasive device102. For example, thefabric106 can be coupled to the abrasive device with amaterial112. In an example, thematerial112 is a hook and loop material, such as Velcro®. In another example, thematerial112 is an adhesive material, such as a pressure sensitive adhesive material. The adhesive material can be applied to theback face126 of thebacking106 in such a manner that permits air flow through theback face126 of thebacking106. For example, a pressure sensitive foam that has an open cell structure can be applied. In another example, a pressure sensitive adhesive can be applied in nodules, lines, or open patterns, only covering a portion of theback face126 of thebacking106.

In an example, thebacking106 includes a fabric including a knittedfront face114 that defines a plurality ofaveoli116. Anaveoli116 is a patterned opening that provides access from thefront surface124 to thehollow space128. The knittedlayer114 is knitted from a plurality of yarns. Each yarn includes a plurality of filaments. In an example, thebinder108 is coated over the knittedlayer114 in a continuous coating without covering theaveoli116.

In addition, the fabric includesthreads118 extending between thefront face124 and theback face126 and defining ahollow space128 between thefront face124 and theback face126. In an example, thethreads118 can be intertwined with the knittedlayer114. In another example, the threads can be adhered to the knittedlayer114.

Optionally, the fabric can include a knittedlayer120. In an example, the knittedlayer120 binds thethreads118 at aback surface126 of thebacking106. The knittedlayer120 can be formed of a plurality of yarns, each including a plurality of filaments. Further, the knittedlayer120 can form a surface onto which thecoupling material112 is disposed. Alternatively, thethreads118 can be adhered together at theback surface126.

In an exemplary use, thefront face124 of theabrasive article104 is placed in contact with a work piece to be abraded, resulting in theabrasive grains110 contacting the work piece. The abradingdevice102 can optionally move theabrasive article104 in a direction parallel to a plane, such as a plane parallel to themajor surface124 of theabrasive article104, for example, in a reciprocating motion, a circular motion, or a combination thereof. Alternatively, a user can facilitate movement of the abrasive article andabrasive device102. As the work piece is abraded, waste material can form. In an example, the waste material can be drawn through theaveoli116 of the knittedlayer114 into thehollow space128 of the abrasive article. In a particular example, theabrasive device102 includes access holes122 through which a vacuum can be applied or air moved. As a result, the waste material can be drawn from thehollow space128 through the optional knittedlayer120 and through the access holes122. In such an example, the waste material is drawn from the work piece and between theabrasive article104 and the work piece through the abrasive article and then to theabrasive device102, preventing dust from being spread into the air or from hindering abrading the work piece.

FIG. 2 andFIG. 3 include illustrations of an exemplaryabrasive article200. Theabrasive article200 includes a knittedlayer202 andthreads204 extending from the knittedlayer202 in a direction opposite an abrasive surface.Abrasive grains212 are secured to the knittedlayer202 by abinder coating210 opposite thethreads204. Optionally, aknitted layer206 is joined to thethreads204 opposite the knittedlayer202.

Theknitted layer202 is formed from a plurality of knitted yarns. Each of the knitted yarns includes a plurality offilaments208. In an example, thefilaments208 are formed of polymeric material, such as a polyamide, a polyester, a polyolefin, polyaramid, polyacrylonitrile, or a combination thereof. An exemplary polyamide includes nylon 6, nylon 6,6, nylon 11, nylon 12, or any combination thereof. In an example, the polyester includes a polyethylene terephthalate. An exemplary polyolefin includes a polyolefin homopolymer, such as polyethylene, polypropylene, polybutene, polypentene, or polymethylpentene; a polyolefin copolymer, such as ethylene-propylene copolymer, ethylene-butene copolymer, or ethylene-octene copolymer; or any combination thereof.

In a particular example, theknitted layer202 forms a set of openings or aveoli316 as illustrated inFIG. 3. The aveoli316 provide access from the front surface of anabrasive article200 to a hollow space defined by thethreads204. In an example, air and waste material can pass through the aveoli316. In particular, the aveoli316 define a pattern of openings. For example, the aveoli316 can be aligned in rows and columns. In another example, the aveoli316 can be aligned in rows that are offset from adjacent rows, as illustrated. Further, the aveoli316 can have a cross section having a shape, such as a triangle, a quadrilateral, a pentagon, hexagon, a heptagon, or another polygon, or any combination thereof. In a further example, the shape can be approximately circular or ovular.

In a further example, the aveoli316 have across dimension320, defined as the longest length across at the opening or aveoli316, in a range of 0.2 mm to 25 mm. For example, the cross dimension can be in a range of 0.2 mm to 10 mm, such as a range of 0.5 mm to 5 mm, or even a range of 0.5 mm to 2 mm. Further, the aveoli316 can be spaced and sized to provide a desired pattern of openings to provide a desirable open area relative to the area defined by the front face of theabrasive article200. For example, the pattern of aveoli316 can provide at least 5% open area relative to the area defined by the front face, such as an open area in a range of 5% to 70%, a range of 15% to 50%, or even a range of 35% to 50% of the area defined by the front face of theabrasive article200.

Thethreads204 define a hollow space on a side of the knittedlayer202 opposite an abrasive surface of theabrasive article200. In an example, thethreads204 are formed of a polymeric material, such as a polyamide, a polyester, a polyolefin, polyaramid, polyacrylonitrile, or a combination thereof. An exemplary polyamide includes nylon 6, nylon 6,6, nylon 11, nylon 12, or any combination thereof. In an example, the polyester includes a polyethylene terephthalate. An exemplary polyolefin includes a polyolefin homopolymer, such as polyethylene, polypropylene, polybutene, polypentene, or polymethylpentene; a polyolefin copolymer, such as ethylene-propylene copolymer, ethylene-butene copolymer, or ethylene-octene copolymer; or any combination thereof.

In particular, thethreads204 are thicker and have a larger cross sectional area than thefilaments208. In an example, thethreads204 can have a diameter at least 50% greater than the diameter of the filaments. For example, the diameter of thethreads204 can be at least 75% greater than the diameter of the filaments, or even at least 100% greater than the diameter of the filaments (e.g., at least twice the diameter of the filaments). A percent increase is calculated relative to the diameter of thefilaments208. In an example, thethreads204 have a diameter in a range of 0.05 mm to 5 mm, such as a range of 0.05 mm to 3 mm, or even a range of 1 mm to 3 mm.

In particular, thethreads204 are joined to theknitted fabric202 mechanically, such as intertwining thethreads204 with theyarns214 of the knittedfabric202. Alternatively, thethreads204 can be punched through theknitted fabric202 and secured to theknitted fabric202 frictionally or with thebinder coating210. In a further alternative example, thethreads204 can be bonded to the knittedlayer202 with an adhesive.

Optional layer

206 can be formed of knitted yarns. In an example, thelayer206 can be knitted to intertwine thethreads204. The yarns of the knittedlayer206 can be yarns similar to the yarns of the knittedlayer202. Alternatively, the yarns of the knittedlayer206 can be different from the yarns of the knittedlayer202. Further, each of the yarns of the knittedlayer206 can be formed of a plurality of filaments. In an alternative embodiment, theknitted layer206 can be knitted with threads, such as threads similar tothreads204 or threads that are different from thethreads204, the threads being a single fiber element as opposed to yarns having a plurality of filaments. Alternatively, theknitted layer206 can be bonded to thethreads204 using an adhesive.

In an example, theknitted layer206 is a loose knit providing porosity for the easy flow of air and dust particles. In an alternative example, theknitted layer206 can be a tight knit construction including additional aveoli.

In a further example, the optional knittedlayer206 forms a surface on which coupling mechanisms can be attached. For example, additional hook or loop structures can be attached to the knittedlayer206 provided that access remains for the passage of air and dust particles. In another example, adhesives can be applied to the optional knittedlayer206.

While not illustrated, additional yarns can extend between the front and back knitted layers (202 or206) through the hollow space of the fabric. Such yarns include a plurality of filaments that have a smaller diameter than thethreads204 that also extend between the front and back knitted layers (202 or206). The optional yarns can be the same as the yarns forming the frontknitted layer202 or the back knittedlayer206. Alternatively, the yarns can be different from the yarns of the knitted layers (202 or206).

Abrasive grains

212 are bonded to the firstknitted layer202 using abinder coating210 opposite thethreads204. In a particular example, thebinder coating210 forms a continuous coating of the knittedlayer202 without covering the aveoli316. For example, thecontinuous surface318 surrounding the aveoli316 can be coated with thebinder coating210 to form a continuous coat of binder. Such a coating is to be differentiated from separated agglomerates which can form a discontinuous layer over a surface. In particular, thebinder coating210 is contiguous with the surface of the frontknitted layer202 formed by the yarns, not including the aveoli.

In an example, the binder is a resin selected from the group consisting of phenolic resin, urea-formaldehyde resin, acrylic resin, epoxy resin, silicone resin, isocyanurate resin, melamine-formaldehyde resin, polyimide resin, or any combination thereof. An exemplary phenolic resin includes resole and novolac. Resole phenolic resins can be alkaline catalyzed and have a ratio of formaldehyde to phenol of greater than or equal to one, such as from 1:1 to 3:1. Novolac phenolic resins can be acid catalyzed and have a ratio of formaldehyde to phenol of less than one, such as 0.5:1 to 0.8:1.

An epoxy resin can include an aromatic epoxy or an aliphatic epoxy. Aromatic epoxies components include one or more epoxy groups and one or more aromatic rings. An example aromatic epoxy includes epoxy derived from a polyphenol, e.g., from bisphenols, such as bisphenol A (4,4′-isopropylidenediphenol), bisphenol F (bis[4-hydroxyphenyl]methane), bisphenol S (4,4′-sulfonyldiphenol), 4,4′-cyclohexylidenebisphenol, 4,4′-biphenol, or 4,4′-(9-fluorenylidene)diphenol. The bisphenol can be alkoxylated (e.g., ethoxylated or propoxylated) or halogenated (e.g., brominated). Examples of bisphenol epoxies include bisphenol diglycidyl ethers, such as diglycidyl ether of Bisphenol A or Bisphenol F. A further example of an aromatic epoxy includes triphenylolmethane triglycidyl ether, 1,1,1-tris(p-hydroxyphenyl)ethane triglycidyl ether, or an aromatic epoxy derived from a monophenol, e.g., from resorcinol (for example, resorcin diglycidyl ether) or hydroquinone (for example, hydroquinone diglycidyl ether). Another example is nonylphenyl glycidyl ether. In addition, an example of an aromatic epoxy includes epoxy novolac, for example, phenol epoxy novolac and cresol epoxy novolac. Aliphatic epoxy components have one or more epoxy groups and are free of aromatic rings. The external phase can include one or more aliphatic epoxies. An example of an aliphatic epoxy includes glycidyl ether of C2-C30 alkyl; 1,2 epoxy of C3-C30 alkyl; mono or multi glycidyl ether of an aliphatic alcohol or polyol such as 1,4-butanediol, neopentyl glycol, cyclohexane dimethanol, dibromo neopentyl glycol, trimethylol propane, polytetramethylene oxide, polyethylene oxide, polypropylene oxide, glycerol, and alkoxylated aliphatic alcohols; or polyols. In one embodiment, the aliphatic epoxy includes one or more cycloaliphatic ring structures. For example, the aliphatic epoxy can have one or more cyclohexene oxide structures, for example, two cyclohexene oxide structures. An example of an aliphatic epoxy comprising a ring structure includes hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, bis(4-hydroxycyclohexyl)methane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, di(3,4-epoxycyclohexylmethyl)hexanedioate, di(3,4-epoxy-6-methylcyclohexylmethyl)hexanedioate, ethylenebis(3,4-epoxycyclohexanecarboxylate), ethanedioldi(3,4-epoxycyclohexylmethyl)ether, or 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,3-dioxane.

An exemplary multifunctional acrylic can include trimethylolpropane triacrylate, glycerol triacrylate, pentaerythritol triacrylate, methacrylate, dipentaerythritol pentaacrylate, sorbitol triacrylate, sorbital hexacrylate, or any combination thereof. In another example, an acrylic polymer can be formed from a monomer having an alkyl group having from 1-4 carbon atoms, a glycidyl group or a hydroxyalkyl group having from 1-4 carbon atoms. Representative acrylic polymers include polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyglycidyl methacrylate, polyhydroxyethyl methacrylate, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyglycidyl acrylate, polyhydroxyethyl acrylate and mixtures thereof.

A silicone resin can, for example, include polyalkylsiloxanes, such as silicone polymers formed of a precursor, such as dimethylsiloxane, diethylsiloxane, dipropylsiloxane, methylethylsiloxane, methylpropylsiloxane, or combinations thereof. In a particular embodiment, the polyalkylsiloxane includes a polydialkylsiloxane, such as polydimethylsiloxane (PDMS). In another example, the silicone polymer can include a polar silicone, such as silicone including halide functional groups, such as chlorine and fluorine, and silicone including phenyls functional groups. For example, the silicone can include trifluoropropylmethylsiloxane polymers. In another exemplary embodiment, the silicone can include polyphenyl methyl siloxane.

Depending upon the catalyzing agents and type of polymer, the binder formulation can be thermally curable or can be curable through actinic radiation, such as UV radiation, to form the binder.

The binder formulation can also include catalysts and initiators. For example, a cationic initiator can catalyze reactions between cationic polymerizable constituents. A radical initiator can activate free-radical polymerization of radically polymerizable constituents. The initiator can be activated by thermal energy or actinic radiation. For example, an initiator can include a cationic photoinitiator that catalyzes cationic polymerization reactions when exposed to actinic radiation. In another example, the initiator can include a radical photoinitiator that initiates free-radical polymerization reactions when exposed to actinic radiation. Actinic radiation includes particulate or non-particulate radiation and is intended to include electron beam radiation and electromagnetic radiation. In a particular embodiment, electromagnetic radiation includes radiation having at least one wavelength in the range of about 100 nm to about 700 nm and, in particular, wavelengths in the ultraviolet range of the electromagnetic spectrum.

Generally, cationic photoinitiators are materials that form active species that, if exposed to actinic radiation, are capable of at least partially polymerizing epoxides or oxetanes. For example, a cationic photoinitiator can, upon exposure to actinic radiation, form cations that can initiate the reactions of cationically polymerizable components, such as epoxies or oxetanes.

An example of a cationic photoinitiator includes, for example, onium salt with anions of weak nucleophilicity. An example includes a halonium salt, an iodosyl salt or a sulfonium salt, a sulfoxonium salt, or a diazonium salt, or any combination thereof. Other examples of cationic photoinitiators include metallocene salt.

In particular examples, the binder formulation includes, relative to the total weight of the composite binder formulation, about 0.1 wt % to about 15 wt % of one or more cationic photoinitiators, for example, about 1 wt % to about 10 wt %.

The binder formulation can optionally include photoinitiators useful for photocuring free-radically polyfunctional acrylates. An example of a free radical photoinitiator includes benzophenone (e.g., benzophenone, alkyl-substituted benzophenone, or alkoxy-substituted benzophenone); benzoin (e.g., benzoin, benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether, benzoin phenyl ether, and benzoin acetate); acetophenone, such as acetophenone, 2,2-dimethoxyacetophenone, 4-(phenylthio)acetophenone, and 1,1-dichloroacetophenone; benzil ketal, such as benzil dimethyl ketal, and benzil diethyl ketal; anthraquinone, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertbutylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone; triphenylphosphine; benzoylphosphine oxides, such as, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; thioxanthone or xanthone; acridine derivative; phenazene derivative; quinoxaline derivative; 1-phenyl-1,2-propanedione-2-O-benzoyloxime; 1-aminophenyl ketone or 1-hydroxyphenyl ketone, such as 1-hydroxycyclohexyl phenyl ketone, phenyl (1-hydroxyisopropyl)ketone and 4-isopropylphenyl(1-hydroxyisopropyl)ketone; or a triazine compound, for example, 4′″-methyl thiophenyl-1-di(trichloromethyl)-3,5-S-triazine, S-triazine-2-(stilbene)-4,6-bistrichloromethyl, or paramethoxy styryl triazine; or any combination thereof.

An exemplary photoinitiator includes benzoin or its derivative such as α-methylbenzoin; U-phenylbenzoin; α-allylbenzoin; α-benzylbenzoin; benzoin ethers such as benzil dimethyl ketal (available, for example, under the trade designation “IRGACURE 651” from Ciba Specialty Chemicals), benzoin methyl ether, benzoin ethyl ether, benzoin n-butyl ether; acetophenone or its derivative, such as 2-hydroxy-2-methyl-1-phenyl-1-propanone (available, for example, under the trade designation “DAROCUR 1173” from Ciba Specialty Chemicals) and 1-hydroxycyclohexyl phenyl ketone (available, for example, under the trade designation “IRGACURE 184” from Ciba Specialty Chemicals); 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (available, for example, under the trade designation “IRGACURE 907” from Ciba Specialty Chemicals); 2-benzyl-2-(dimethlamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (available, for example, under the trade designation “IRGACURE 369” from Ciba Specialty Chemicals); or a blend thereof.

Another useful photoinitiator includes pivaloin ethyl ether, anisoin ethyl ether; anthraquinones, such as anthraquinone, 2-ethylanthraquinone, 1-chloroanthraquinone, 1,4-dimethylanthraquinone, 1-methoxyanthraquinone, benzanthraquinonehalomethyltriazines, and the like; benzophenone or its derivative; iodonium salt or sulfonium salt as described hereinabove; a titanium complex such as bis(η5-2,4-cyclopentadienyl)bis[2,-6-difluoro-3-(1H-pyrrolyl)phenyl)titanium (commercially available under the trade designation “CGI784DC”, also from Ciba Specialty Chemicals); a halomethylnitrobenzene such as 4-bromomethylnitrobenzene and the like; or mono- or bis-acylphosphine (available, for example, from Ciba Specialty Chemicals under the trade designations “IRGACURE 1700”, “IRGACURE 1800”, “IRGACURE 1850”, and “DAROCUR 4265”). A suitable photoinitiator can include a blend of the above mentioned species, such as α-hydroxy ketone/acrylphosphin oxide blend (available, for example, under the trade designation IRGACURE 2022 from Ciba Specialty Chemicals).

A further suitable free radical photoinitiator includes an ionic dye-counter ion compound, which is capable of absorbing actinic rays and producing free radicals, which can initiate the polymerization of the acrylates.

A photoinitiator can be present in an amount not greater than about 20 wt %, for example, not greater than about 10 wt %, or not greater than about 5 wt %, based on the total weight of the binder formulation. For example, a photoinitiator can be present in an amount of 0.1 wt % to 20.0 wt %, such as 0.1 wt % to 5.0 wt %, or 0.1 wt % to 2.0 wt %, based on the total weight of the binder formulation, although amounts outside of these ranges can also be useful. In one example, the photoinitiator is present in an amount at least about 0.1 wt %, such as at least about 1.0 wt % or in an amount 1.0 wt % to 10.0 wt %.

The binder formulation can also include other components such as solvents, plasticizers, crosslinkers, chain transfer agents, stabilizers, dispersants, curing agents, reaction mediators and agents for influencing the fluidity of the dispersion. For example, the binder formulation can also include one or more chain transfer agents selected from the group consisting of polyol, polyamine, linear or branched polyglycol ether, polyester and polylactone.

Theabrasive grains212 can be formed of any one of or a combination of abrasive grains, including silica, alumina (fused or sintered), zirconia, zirconia/alumina oxides, silicon carbide, garnet, diamond, cubic boron nitride, silicon nitride, ceria, titanium dioxide, titanium diboride, boron carbide, tin oxide, tungsten carbide, titanium carbide, iron oxide, chromia, flint, emery, or any combination thereof. For example, theabrasive grains212 can be selected from a group consisting of silica, alumina, zirconia, silicon carbide, silicon nitride, boron nitride, garnet, diamond, cofused alumina zirconia, ceria, titanium diboride, boron carbide, flint, emery, alumina nitride, or a blend thereof. Particular embodiments have been created by use of dense abrasive grains comprised principally of alpha-alumina.

Theabrasive grains212 can also have a particular shape. An example of such a shape includes a rod, a triangle, a pyramid, a cone, a solid sphere, a hollow sphere or the like. Alternatively, theabrasive grain212 can be randomly shaped.

Theabrasive grains212 generally have an average grain size not greater than 2000 microns, such as not greater than about 1500 microns. In another example, the abrasive grain size is not greater than about 750 microns, such as not greater than about 350 microns. For example, the abrasive grain size can be at least 0.1 microns, such as from about 0.1 microns to about 1500 microns, and more typically from about 0.1 microns to about 200 microns or from about 1 micron to about 100 microns. The grain size of theabrasive grains212 is typically specified to be the longest dimension of the abrasive grain. Generally, there is a range distribution of grain sizes. In some instances, the grain size distribution is tightly controlled.

In a blended abrasive slurry including theabrasive grains212 and the binder formulation, theabrasive grains212 provide from about 10% to about 90%, such as from about 30% to about 80%, of the weight of the abrasive slurry.

The binder formulation, abrasive slurry, or abrasive layer can further include a grinding aid to increase the grinding efficiency and cut rate. A useful grinding aid can be inorganic based, such as a halide salt, for example, sodium cryolite, and potassium tetrafluoroborate; or organic based, such as a chlorinated wax, for example, polyvinyl chloride. A particular embodiment includes cryolite and potassium tetrafluoroborate with particle size ranging from 1 micron to 80 microns, and most typically from 5 microns to 30 microns. The weight percent of grinding aid is generally not greater than about 50 wt %, such as from about 0 wt % to 50 wt %, and most typically from about 10 wt % to 30 wt % of the entire slurry (including the abrasive grains).

In addition, the abrasive layer can be treated with a coating of an anti-loading material. An exemplary anti-loading material includes metal silicates, silicas, metal carbonates, metal sulfates or any combination thereof. The metal silicates can include consisting of magnesium silicates, potassium aluminum silicates, aluminum silicates, calcium silicates, or any combination thereof. In one embodiment, the magnesium silicates include talc, the potassium aluminum silicates include micas, the aluminum silicates include clays, and the calcium silicates include wollastonite. The silicas can be selected from the group consisting of fused silica, fumed silica, and precipitated amorphous silica. The metal carbonates can include calcium carbonate. The metal sulfates can include hydrous calcium sulfate or anhydrous calcium sulfate. In a further example, the anti-loading material can include a metal salt of a long chain fatty acid, such as a metal stearate, for example, sodium, calcium, or magnesium stearate.

To form the abrasive article, the fabric of the backing can be dispensed, for example in a continuous process. Alternatively, the process can be a batch process and the fabric can be provided in cut sheets ready for processing. The fabric includes a front face and a back face and the front face includes a set of knitted yarns defining the aveoli. A binder formulation is applied to the front face of the fabric, and abrasive grains are applied to the front face of the fabric over the binder formulation to be adhered with the binder to the front face. In particular, the binder formulation can be applied to form a continuous layer of binder. For example, the binder formulation can be calendared to the front face of the fabric. The abrasive grains can be applied over the binder formulation, and bonded to the fabric. In a particular example, the abrasive grains can be deposited on to the binder, such as through electrostatic deposition.

Alternatively, the binder and abrasive can be applied in combination as a slurry. For example, a slurry including the binder formulation and abrasive grains can be coated on to the front face of the fabric, such as by calendaring. In another example, the binder formulation can be applied using other coating techniques, such as spray coating, dip coating, or any combination thereof.

In particular, the abrasive article has desirable properties resulting from its construction. For example, the abrasive article can have a desirable flow through rate. Air permeability of the abrasive article is evaluated using a Texttest AG (Switzerland) Model 3300 Air Permeability Tester with a test pressure of 200 Pa and a test head area of 20 cm². In an example, the air permeability is at least 1000 mm/s, such as at least 1200 mm/s, at least 1400 mm/s, at least 1600 mm/s, at least 2000 mm/s, or even at least 3000 mm/s. In particular, the air permeability can be in a range of 1000 mm/s to 6000 mm/s, such as a range of 1200 mm/s to 6000 mm/s, a range of 1600 mm/s to 5500 mm/s, or even a range of 2100 mm/s to 5500 mm/s.

In addition, the abrasive article can provide desirable material removal rates. For example, Material Removal Performance is defined as the cumulative material removal over a 10 minute period as determined in accordance with the method of Example 1. The abrasive article can have a Material Removal Performance of at least 1 gram, such as at least 1.5 grams, at least 2.0 grams, at least 3.0 grams, at least 4.0 grams, or even at least 4.2 grams.

In another example, the abrasive article can have a desirable spring back or conformability. The conformable nature of the abrasive article allows it to compensate for moderate curvature within the component being abraded. Springy nature helps to keep the abrasive layers in contact with the surface, particularly an uneven surface, and provides near constant force on the abrasive layers, preventing uneven abrading due to excessive force in one region relative to another.

In particular, the abrasive article has a desirable force to compress at 30% compression and 50% compression. For example, the abrasive article can have a force-to-compress as measured in accordance with ASTM D1667 as modified to receive the compressible construction of the abrasive article and measured instantaneously, of at least 0.5 N/cm²at 50% compression. In an example, the abrasive article has a 50% force-to-compress of at least 1.0 N/cm², such as at least 2.0 N/cm². In a further example, the abrasive article can have a 50% force-to compress of not greater than 12 N/cm², such as not greater than 10 N/cm², not greater than 8 N/cm², or even not greater than 7 N/cm².

In a further example, the force-to-compress at 30% compression can be at least 0.5 N/cm², such as at least 0.7 N/cm², at least 1.1 N/cm², or even at least 1.3 N/cm². In an additional example, the force-to-compress at 30% compression can be not greater than 10 N/cm², such as not greater than 8.5 N/cm², not greater than 5 N/cm², or even not greater than 3 N/cm².

EXAMPLEExample 1

Sample abrasive articles are prepared using either phenolic resin binder or urea-formaldehyde binder and P320 semi-friable aluminum oxide grains. The samples may or may not have an anti-loading layer formed of a metal stearate. Samples are compared with comparative samples of A295 and A277 abrasive articles, available from Saint-Gobain.

To determine Material Removal Performance (MRP), defined as the cumulative material remove after 10 minutes of grinding, expressed in grams, the samples are formed into 100 mm diameter disks and attached to an orbital grinder. Work pieces formed of a plexiglas panel are abraded for 10 minutes and loss in weight measured. The Material Removal Performance is illustrated in Table 1.

TABLE 1

Material Removal Performance of Abrasive Samples

	Material	Anti-loading	MRP (grams)

Sample 1	Phenolic Resin	No	0.32
Sample 2	Urea-formaldehyde	No	0.79
Sample 3	Phenolic Resin	Yes	1.84
Sample 4	Phenolic Resin	Yes	4.23
Sample 5	Urea-formaldehyde	Yes	1.4
A295	Urea-formaldehyde	Yes	3.83
A277	Urea-formaldehyde	Yes	4.18

As illustrated in Table 1, the samples provide desirable MRP of as much as 4.2 grams.

Example 2

Air permeability is evaluated using a Texttest AG (Switzerland) Model 3300 Air Permeability Tester, which measures the rate of air flow through a known area. The air permeability is determined from the pressure drop across the orifice. For the tests, a test pressure of 200 Pa is used with a test head area of 20 cm². The air permeability is expressed as volume of flow per unit surface area per second i.e., as mm/s (=(mm³/mm²)/s).

Open-mesh backings from different suppliers are tested. In addition, samples formed with open-mesh backing and including phenolic resin binder and abrasive grains with a Velcro® layer are tested. Further, Multi-Air and Multi-Air soft-touch products A275 available from Saint-Gobain, and Abranet and Abranet soft products available from Mirka are tested. Table 2 illustrates the air permeability.

TABLE 2

Air Permeability of Backing and Samples.

		Standard
	Air permeability	deviation
	(average; mm/s)	(mm/s)

Open-mesh backing 0	4475	19
Open-mesh backing 1	4493	63
Open-mesh backing 3	5408	17
Open-mesh backing 4	3280	65
Open-mesh backing 5	3478	46
Open-mesh backing 6	4833	139
Open-mesh backing 7	884	123
O-M backing 3 with resin (phenolic)	4475	7
Sample 1 (with O-M 3 + resin + grain +	1667	38
Velcro layer)
Sample 2 (with O-M 4 + resin + grain +	1427	146
Velcro layer)
Sample 3 (with O-M X + resin + grain +	2252	105
Velcro layer)
Multi-air A275 P400	1526	395
Multi-air “Soft-touch” A275 P400	1602	414
Abranet P400	10175	96
Abranet Soft P800	1105	51

As illustrated in Table 2, Samples 1 and 2 exhibit comparable air permeability to commercial comparative samples. Sample 3 exhibits desirably greater air permeability than other commercial samples.

Example 3

Compressibility and spring back of the abrasive articles are determined based on force-to-compress testing at 30% compression and 50% compression. Force-to-compress is measured in accordance with ASTM D1667 as modified to receive a compressible material having a surface area of 650 mm²and measured instantaneously instead of waiting 60 seconds.

Open-mesh backings from different suppliers are tested. In addition, samples formed with open-mesh backing and including phenolic resin binder and abrasive grains with a Velcro® layer are tested. Further, a Multi-Air soft-touch product A975 available from Saint-Gobain is tested. Table 3 illustrates the force-to-compress.

TABLE 3

Force-to-Compress of Samples

	F (N/cm²)	F (N/cm²) 50%
Sample (650 mm²)	30% Compression	Compression

Open-mesh backing 0	6.8	8.3
Open-mesh backing 1	8.5	9.5
Open-mesh backing 2	8.2	9.4
Open-mesh backing 3	0.7	0.9
Open-mesh backing 4	0.7	0.7
Open-mesh backing 5	0.8	1.5
O-M backing 3 with resin (phenolic)	0.7	1.4
Sample 1	0.8	2.1
Sample 3	1.5	2.7
Multi-air Softouch A975 P400	0.4	1.0

As illustrated in Table 3, the sample abrasive articles exhibit greater force-to-compress that then comparative sample, yet are not stiff or rigid. In addition, as illustrated above in Table 2, the samples exhibit similar or greater permeability than the comparative sample.

In a first aspect, an abrasive article includes a fabric comprising a front face and a back face. The front face is formed of first knitted yarns. Each yarn of the first knitted yarns includes a plurality of filaments. A plurality of threads is intertwined with the first knitted yarns and extends between the front face and the back face. The plurality of threads defines a hollow space between the front face and the back face. The abrasive article also includes abrasive grains adhered to the front face of the fabric.

In an example of the first aspect, the abrasive article has a force-to-compress at 50% compression of at least 0.5 N/cm², such as at least 1.0 N/cm², or at least 2.0 N/cm². The force-to-compress at 50% compression can be not greater than 12.0 N/cm², such as not greater than 10 N/cm².

In a further example of the first aspect, the threads have a diameter at least 50% greater than the diameter of the filaments, such as at least 75% greater than the diameter of the filaments, or at least 100% greater than the diameter of the filaments. The diameter can be between 0.05 mm and 5 mm.

In an additional example, the knitted yarns define a pattern of openings. Each opening in the pattern of openings can have a cross-dimension in a range of 0.2 mm to 25 mm, such as a range of 0.2 mm to 10 mm, or a range of 0.5 mm to 5 mm.

In an example, the pattern of openings provides at least 5% open area relative to the area defined by the front face, such as a range of 5% to 70% of the area, a range of 15% to 50% of the area, or a range of 35% to 50% of the area defined by the front face.

In a further example, the threads include polyamide. In another example, the filaments include polyester. In an additional example, the filaments include polyamide.

In an additional example, the abrasive article further includes a binder. The binder adheres to the abrasive grains to the front face. The binder is a resin selected from the group consisting of phenolic resin, ureaformaldahyde resin, acrylic resin, epoxy resin, silicone resin, isocyanurate resin, melamine-formaldehyde resin, polyimide resin, or any combination thereof. For example, the binder is thermally curable. In another example, the binder is radiation curable. In an additional example, the binder forms a layer contiguous with the first knitted yarns of the front face of the fabric.

In a further example, the back face includes second knitted yarns. The plurality of threads is intertwined with the second knitted yarns of the back face.

In a second aspect, an abrasive article includes a fabric including a front face and a back face. The front face is formed of first knitted yarns. Each yarn of the first knitted yarns includes a plurality of filaments. A plurality of threads is intertwined with the first knitted yarns and extends between the front face and the back face. The back face is formed of second knitted yarns. The plurality of threads is intertwined with the second knitted yarns. The threads define a hollow space between the front face and the back face. The abrasive article further includes a binder disposed on the front face of the fabric and abrasive grains adhered to the binder.

In an example of the second aspect, the binder is contiguous with the first knitted yarns. In a further example, the threads have a diameter at least 50% greater than the diameter of the filaments.

In an additional example, the first knitted yarns define a pattern of openings. In another example, the abrasive article has a force-to-compress at 50% compression of at least 0.5 N/cm²or not greater than 12.0 N/cm².

In a third aspect, an abrasive article includes a fabric comprising a front face and a back face. The front face is formed of first knitted yarns. A plurality of threads extends between the front face and the back face. The plurality of threads defines a hollow space between the front face and the back face. The abrasive article further includes abrasive grains adhered to the front face of the fabric. The abrasive article has a force-to-compress at 50% compression of at least 0.5 N/cm². In an example of the third aspect, the abrasive article has a force-to-compress at 50% compression of at least 1.0 N/cm²or not greater than 12.0 N/cm².

In a further example, the first knitted yarns define a pattern of openings. For example, each opening in the pattern of openings has a cross-dimension in a range of 0.2 mm to 25 mm. In an example, the pattern of openings provides at least 5% open area relative to the area defined by the front face.

In an additional example, the abrasive article includes a binder. The binder adheres the abrasive grains to the front face. For example, the binder is a resin selected from the group consisting of phenolic resin, urea-formaldehyde resin, acrylic resin, epoxy resin, silicone resin, isocyanurate resin, melamine-formaldehyde resin, polyimide resin, or any combination thereof.

In another example, the binder forms a layer contiguous with the first knitted yarns of the front face of the fabric. In an example, the back face includes second knitted yarns. The plurality of threads is intertwined with the second knitted yarns of the back face.

In a fourth aspect, a method of forming an abrasive article includes dispensing a fabric comprising a front face and a back face. The front face is formed of first knitted yarns. Each yarn of the first knitted yarns includes a plurality of filaments. A plurality of threads is intertwined with the first knitted yarns and extends between the front face and the back face. The threads define a hollow space between the front face and the back face. The method further includes applying a binder formulation to the front face of the fabric and applying abrasive grains to the front face of the fabric. In an example of the fourth aspect, the back face is formed of second knitted yarns and the plurality of threads is intertwined with the second knitted yarns.

In an example of the fourth aspect, applying the binder formulation includes forming a layer of the binder formulation contiguous with the first knitted yarns. In another example, applying the binder formulation and applying the abrasive includes applying a slurry comprising the abrasive grains and the binder formulation. In an additional example, applying the binder formulation includes calendering the binder formulation to the front face of the fabric. In a further example, applying the abrasive grains includes depositing the abrasive grains by electrostatic deposition.

In a fifth aspect, a method of abrading a work piece includes coupling an abrasive article to an abrading device. The abrading device is to repetitively move the abrasive article parallel to a plane. The abrasive article includes a fabric including a front face and a back face. The front face is formed of first knitted yarns. Each yarn of the first knitted yarns includes a plurality of filaments. A plurality of threads is intertwined with the first knitted yarns and extends between the front face and the back face. The threads defines a hollow space between the front face and the back face. The abrasive article further includes abrasive grains adhered to the front face of the fabric. The method further includes contacting the front face of the abrasive article to a surface of the work piece and drawing abraded material from the front face of the abrasive article to the back face through the hollow space.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed.

In the foregoing specification, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of invention.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

After reading the specification, skilled artisans will appreciated that certain features are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, references to values stated in ranges include each and every value within that range.