Nonwoven abrasive article and method for making same

Abstract

The nonwoven abrasive article includes a prebond composition disposed on a lofty, open nonwoven fibrous web and an abrasive layer disposed and secured on at least a portion of the prebond composition. The abrasive layer includes a binder composition that holds abrasive particles. At least one of the prebond composition and the binder composition includes a reaction product of a polymer having a plurality of oxazolinyl groups. A method of making the nonwoven abrasive article is also disclosed.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to nonwoven abrasive articles and methods of making and using them. [Background technology]

[0002] Nonwoven abrasive articles are known, for example, as described in U.S. Patent No. 2,958,593 (Hoover et al.), and generally comprise fibers formed into a nonwoven web provided as a perforated three-dimensional integrated network structure to which an abrasive layer is attached. The abrasive layer typically comprises abrasive particles held in a crosslinked binder.

[0003] Often the fibers are formed into a lofty, open nonwoven fibrous web, as described, for example, in U.S. Patent No. 5,591,239 (Larson). A prebond coating of abrasive-free curable prebond precursor solution containing one or more of the above resins is coated onto the web and cured (e.g., by exposure to heat) to impart sufficient strength to the nonwoven web for further processing.

[0004] Such nonwoven abrasive articles are useful in individual sheet form as well as in various converted forms, such as, for example, wheels, discs, and flap brushes, etc. In these converted forms, the resulting articles are useful for polishing, cleaning, conditioning, and / or decorating the surfaces of materials such as metals, wood, plastics, glass, ceramics, and composites.

[0005] One known type of nonwoven abrasive product includes an abrasive layer that contains a binder that holds polyamide fibers and abrasive particles. However, the phenolic binder and the polyamide fibers have different physical properties, such as flexibility and composition, and therefore the polyamide fibers and the abrasive layer may delaminate during use, which may cause fraying of the fibers and shorten the product life. Summary of the Invention

[0006] Although various technical solutions have been attempted, to date, there remains a need for a solution to the problem of poor wear performance leading to reduced product life. Advantageously, the present disclosure provides such a new nonwoven abrasive article that exhibits improved wear performance.

[0007] In one aspect, the present disclosure provides a nonwoven abrasive article comprising a lofty, open-weave nonwoven fibrous web, a prebond composition disposed on at least a portion of the lofty, open-weave nonwoven fibrous web, and an abrasive layer disposed and secured on at least a portion of the prebond composition, wherein the abrasive layer comprises a binder composition that holds abrasive particles, and at least one of the prebond composition and the binder composition comprises a reaction product of a polymer having a plurality of oxazolinyl groups.

[0008] In another aspect, the present disclosure provides a method of making a nonwoven abrasive article comprising: disposing a curable prebond precursor composition on at least a portion of a lofty, open-weave nonwoven fibrous web; at least partially curing the curable prebond precursor composition to provide a prebond composition; disposing an abrasive layer precursor composition on at least a portion of the prebond composition, the abrasive layer precursor composition comprising a phenolic resin and abrasive particles; and at least partially curing the abrasive layer precursor composition, wherein at least one of the curable prebond precursor composition and the abrasive layer precursor composition comprises a polymer having a plurality of oxazolinyl groups.

[0009] In another aspect, the present disclosure provides a method of making a nonwoven abrasive article comprising: disposing a curable prebond precursor composition on at least a portion of a lofty, open-weave nonwoven fibrous web; at least partially curing the curable prebond precursor composition to provide a prebond composition; disposing a curable make layer precursor composition on at least a portion of the prebond composition, where the curable make layer precursor composition comprises a phenolic resin; at least partially embedding abrasive particles in the curable make layer precursor composition; and at least partially curing the curable make layer precursor composition to provide an at least partially cured make layer composition, where at least one of the curable prebond precursor composition and the curable make layer precursor composition comprises a polymer having a plurality of oxazolinyl groups.

[0010] In some embodiments, methods according to the present disclosure further include disposing a curable size layer precursor composition on the at least partially cured make layer composition and at least partially curing the curable size layer precursor composition.

[0011] As used herein, "Nonwoven" refers to any web of fibers that is held together by interlocking or bonding (such as by chemical or thermal means) and that is not woven, knitted, or felted.

[0012] "Acrylic polymer" refers to any polymer that contains one or more monomer units corresponding to the residues of (meth)acrylic acid, a (meth)acrylate ester, (meth)acrylonitrile, or an optionally substituted (meth)acrylamide.

[0013] "Polyurethane" refers to a polymer having multiple carbamylene (ie, --OC(.dbd.O)NH--) groups.

[0014] "(Meth)acrylic" means one or both of acrylic and methacrylic.

[0015] The features and advantages of the present disclosure will be further understood by consideration of the detailed description and the appended claims. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic perspective view of an exemplary nonwoven abrasive article 100. [Diagram 2] For convenience, a schematic enlargement of an individual coated fiber within the nonwoven abrasive article 100 shown in FIG.

[0017] Repeat use of reference characters in the specification and drawings is intended to represent the same or similar features or elements of the present disclosure. It is to be understood that those skilled in the art can devise numerous other modifications and embodiments that are within the scope and spirit of the principles of the present disclosure. The figures may not be drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 1, an exemplary nonwoven abrasive article 100 includes a lofty, open nonwoven fibrous web 110 that includes fibers 120. Now referring to FIGURE 2, a prebond composition 130 is disposed on the fibers 120. An abrasive layer 140 is disposed on and secured to at least a portion of the prebond composition 130. The abrasive layer 140 includes a phenolic binder 150 that holds abrasive particles 160.

[0019] Suitable bulky and open nonwoven fiber webs (hereinafter, for convenience, referred to as "nonwoven fiber webs") for use are known in the abrasive art. The fibers may include continuous fibers, staple fibers, or a combination thereof. For example, the fiber web may include staple fibers having a length of at least about 20 millimeters (mm), at least about 30 mm, or at least about 40 mm, and less than about 110 mm, less than about 85 mm, or less than about 65 mm, although shorter and longer fibers (e.g., continuous filaments) may also be useful. The fibers may have a fineness or linear density of at least about 1.7 decitex (dtex, i.e., grams / 10,000 meters), at least about 6 dtex, or at least about 17 dtex, and less than about 560 dtex, less than about 280 dtex, or less than about 120 dtex, although fibers with smaller and / or larger linear densities may also be useful. A mixture of fibers with different linear densities may also be useful, for example, to provide an abrasive article that produces a particularly favorable surface finish when used.

[0020] Nonwoven fibrous webs can be produced, for example, by conventional airlaid, carded, stitchbonded, spunbonded, wetlaid, and / or meltblown procedures. Airlaid fibrous webs can be made, for example, using equipment such as that available from Rando Machine Company (Macedon, New York) under the trade designation "RANDO WEBBER."

[0021] The nonwoven fibrous web is typically selected to be compatible with the adhesive binder and abrasive particles, as well as with other components of the article, and typically can withstand the processing conditions (e.g., temperature) used during application and curing of the curable binder precursor. Although many types of fibers can be included, at least a portion of the fibers in the nonwoven fibrous web include polyamides, preferably aliphatic polyamides. Blends of polyamides with other polymers may also be used. Preferably, at least 50 percent, at least 60 percent, at least 70 percent, at least 80 percent, at least 90 percent, at least 99 percent, or even 100 percent of the fibers, by weight, include at least one polyamide. Exemplary polyamides include aliphatic polyamides such as poly(caprolactam) (i.e., nylon 6), poly(hexamethylene / adipic acid)amide (i.e., nylon 6,6), poly(hexamethylene / sebacic acid)amide (i.e., nylon 6,10), and aliphatic polyamide copolymers; semi-aromatic polyamides such as polyphthalamide (e.g., PPA); and aromatic polyamides such as p-phenylenediamine / terephthalic acid polymers (e.g., available under the trade names Kevlar and Nomex).

[0022] Other fibers can be selected to affect the properties of the nonwoven abrasive article, such as, for example, flexibility, elasticity, durability or service life, abrasion, and finish characteristics. Examples of other fibers that may be suitable include natural fibers, synthetic fibers, and mixtures of natural and / or synthetic fibers. Examples of synthetic fibers include those made from polyester (e.g., polyethylene terephthalate), polypropylene, acrylonitrile (i.e., acrylic), rayon, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymer, and vinyl chloride-acrylonitrile copolymer. Examples of suitable natural fibers include cotton, jute, and linen. The fibers may be from virgin materials or from recycled or waste materials reclaimed, for example, from clothing cuttings, carpet manufacturing, textile manufacturing, or textile processing. The fibers may be homogenous or composite, such as bicomponent fibers (e.g., co-spun sheath-core fibers). The fibers may be stretched and crimped, but also continuous filaments, such as those formed in an extrusion process. Combinations of fibers may be used.

[0023] Prior to coating with the prebond precursor composition, the nonwoven fibrous web typically has a weight per unit area (i.e., basis weight) of at least about 50 grams per square meter (gsm), at least about 100 gsm, or at least about 150 gsm, and / or less than about 600 gsm, less than about 500 gsm, or less than about 400 gsm, measured before any coating (e.g., with a curable binder precursor or optional prebond resin), although larger and smaller basis weights may be used. Further, prior to coating with the prebond precursor composition, the fibrous web typically has a thickness of at least about 3 mm, at least about 6 mm, or even at least about 10 mm, and / or less than about 100 mm, less than about 50 mm, or less than about 25 mm, in any subcombination, although thicker and thinner thicknesses may also be useful.

[0024] It is beneficial to apply a prebond composition to the nonwoven fibrous web before coating with the curable binder precursor. The prebond composition can, for example, help to maintain the integrity of the nonwoven fibrous web during handling and can also promote adhesion of the urethane binder to the nonwoven fibrous web. Examples of prebond resins include phenolic resins, urethane resins, glues, acrylic resins, urea formaldehyde resins, melamine formaldehyde resins, epoxy resins, and combinations thereof. The amount of prebond resin used in this manner is typically adjusted to a minimum amount consistent with bonding the fibers together at the crosslinking junctions. If the nonwoven fibrous web includes thermally bondable fibers, thermal bonding of the nonwoven fibrous web may also be beneficial to maintain the integrity of the web during processing. The prebond composition is formed by at least partially curing, and preferably at least substantially curing, the curable prebond precursor composition.

[0025] In one embodiment, the prebond precursor composition includes a polymer having multiple oxazolinyl groups and a polyurethane having multiple carboxyl groups. On a solids basis, the polymer having multiple oxazolinyl groups and the polyurethane are present in a weight ratio of 1:99 to 8:92 (preferably 1:99 to 7:93). Preferably, at least one of the polymer having multiple oxazolinyl groups, the polyurethane, and the prebond precursor composition, and more preferably all of them, are water-based, although this is not required.

[0026] Useful polymers having multiple oxazolinyl groups can include acrylic polymers, such as methacrylic polymers. Useful (meth)acrylic polymers having multiple oxazolinyl groups can be copolymers of free radically polymerizable oxazoline functional monomers and one or more (meth)acrylic monomers.

[0027] Exemplary free radically polymerizable oxazoline functional monomers include 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, and various substituted derivatives as described in US Pat. No. 3,839,350 (Hunsucker).

[0028] Exemplary (meth)acrylic monomers include (meth)acrylic acid, (meth)acrylonitrile, (meth)acrylamide, (meth)acrylic acid esters (e.g., methyl (meth)acrylate, ethyl methacrylate, 2-hydroxyethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate), isobutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate), (meth)acrylonitrile, or optionally substituted (meth)acrylamides, 2-phenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, allyl (meth)acrylate, lauryl (meth)acrylate. In some embodiments, the (meth)acrylic monomer is an alkyl (meth)acrylate having 1 to 8 carbon atoms.

[0029] In some embodiments, additional non-acrylic free radically polymerizable monomers may be included in the (meth)acrylic polymer having multiple oxazolinyl groups. Exemplary such monomers include styrene and substituted styrenes.

[0030] Suitable commercially available (meth)acrylic polymers having multiple oxazolinyl groups include those sold under the trade name EPOCROS by Nippon Shokubai Co. Ltd., Osaka, Japan. Examples may include WS-based polymers such as WS-300, WS-500, WS-700, which are acrylic water-soluble polymers having multiple oxazolinyl groups. Examples may also include K-2000-based polymers such as K-2010E, K-2020E, K-2035E, which are styrene / acrylic emulsion polymers having multiple oxazolinyl groups.

[0031] The amount of oxazolinyl-containing polymer contained in a composition (either the curable precursor composition or the cured composition) can be expressed as parts per hundred parts of resin (PHR). In this specification, the PHR is calculated based on dividing the non-volatile content in the oxazolinyl-containing polymer by the non-volatile content in the non-oxazolinyl resin in the precursor composition, and the PHR is expressed as parts per hundred parts. For example, if a precursor composition contains 6.01 grams of an oxazolinyl-containing polymer solution having a non-volatile content of 25% and 71.66 grams of a non-oxazolinyl resin solution having a non-volatile content of 70%, a PHR of 3 is obtained.

[0032] In some embodiments, the prebond precursor composition can include a polymer having multiple oxazolinyl groups in an amount of at least 0.5 PHR, 1 PHR, 3 PHR, or 5 PHR. In some embodiments, the prebond precursor composition can include a polymer having multiple oxazolinyl groups in an amount of 20 PHR, 15 PHR, or 10 PHR or less. Advantageously, the nonwoven abrasive article according to the present disclosure provides good cutting and finishing performance while exhibiting less wear and longer abrasive life of the abrasive article.

[0033] Methods for making carboxylated polyurethanes are well known and are described, for example, in Liu et al. "Continuous Production of Water-Borne Polyurethanes: A Review," Polymers 2020, 12, pp. 2875. There are many techniques for producing aqueous carboxylated polyurethane dispersions, including incorporating carboxylic acid moieties into the polyurethane backbone to act as an internal emulsifier. This internal emulsifier can be achieved, for example, by using a carboxylated diol, such as dimethylolpropionic acid (DMPA), which is co-reacted with a polyol and an isocyanate and then neutralized with a base to facilitate dispersion of the polyurethane particles in water. DMPA levels vary from 4% to 8% by weight of the prepolymer weight.

[0034] Many carboxylated polyurethane dispersions are commercially available. Examples include those available under the trade name ADEKA BONTIGHTER HUX-386 from Adeka Corporation, Tokyo, Japan; those available under the trade name HYDRAN HW-110, HYDRAN HW-131, HYDRAN HW-135, HYDRAN HW-320, HYDRAN HW-311, HYDRAN HW-337, HYDRAN 340, HYDRAN WLS-201, and BONDIC 72070, all from DIC Corporation, Tokyo, Japan; those available under the trade name NEOSTECKER 400 and NEOSTECKER 700 from NICCA CHEMICAL CO., LTD., Fukui, Japan; and those available under the trade name VYLONAL MD-1200, VYLONAL MD-1400, and VYLONAL MD-1930 from TOYOBO CO., LTD., Osaka, Japan. Combinations of carboxylated polyurethanes may also be used.

[0035] Useful compositions of the curable prebond precursor composition can include aqueous dispersions of 3% to 85%, 30% to 85%, 51% to 85%, and 70% to 85% by weight solids, although greater and lesser amounts can be used. The curable prebond precursor composition may be applied to the nonwoven fibrous web by any suitable means, such as, for example, roll coating, spray coating, or saturation coating. In some embodiments, the curable prebond precursor composition can also include additional additives, such as, for example, wetting agents, leveling agents, colorants, biocides, fungicides, thixotropic agents, and antioxidants.

[0036] After the curable prebond precursor composition is applied to the nonwoven fibrous web, it is then at least partially cured, preferably at least substantially cured, for example by heating in an oven at high temperature. This helps to provide strength to the nonwoven fibrous web and maintain its bulky, open structure. The selection of temperature may depend on factors such as the particular composition of the curable prebond precursor composition and / or the fibers, and is within the ability of one skilled in the art.

[0037] An abrasive layer is then placed and secured over at least a portion of the prebond composition. The abrasive layer includes a binder composition that holds the abrasive particles. This can be done in at least two ways.

[0038] In the first method, an abrasive layer precursor composition (typically a slurry) containing a curable binder precursor composition and abrasive particles is impregnated into a nonwoven fibrous web or otherwise coated (e.g., by roll coating or spray coating) onto at least a portion of the prebond layer.

[0039] In some embodiments according to the present disclosure, the polishing layer precursor composition comprises a polymer having multiple oxazolinyl groups. Useful polymers having multiple oxazolinyl groups can include acrylic polymers, such as methacrylic polymers. Useful (meth)acrylic polymers having multiple oxazolinyl groups can be copolymers of free radically polymerizable oxazoline functional monomers and one or more (meth)acrylic monomers. Exemplary free radically polymerizable oxazoline functional monomers include 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, and various substituted derivatives described in U.S. Pat. No. 3,839,350 (Hunsucker). Additional non-acrylic free radically polymerizable monomers can be included in the (meth)acrylic polymer having multiple oxazolinyl groups. Exemplary such monomers include styrene and substituted styrenes.

[0040] In some embodiments, the curable binder precursor can include a polymer having multiple oxazolinyl groups in an amount of at least 0.5 PHR, 1 PHR, 3 PHR, or 5 PHR. In some embodiments, the prebond precursor composition can include a polymer having multiple oxazolinyl groups in an amount of up to 20 PHR, 15 PHR, 10 PHR, or 5 PHR. Advantageously, the nonwoven abrasive article according to the present disclosure provides good cutting and finishing performance while exhibiting less wear and longer abrasive life of the abrasive article.

[0041] Examples of suitable curable binder precursors include resole-type phenolic resins, novolac-type phenolic resins, epoxy resins, polymerizable acrylic monomer oligomers and polymers, alkyd resins, cyanate resins, aminoplast resins, urea-formaldehyde resins, urethane resins (one-pack and two-pack), and combinations thereof. Depending on the curable binder precursor system selected, a suitable curing agent (e.g., crosslinker, catalyst, or initiator) may be present. The selection and amount of such suitable curing agent is well known in the abrasives technical field.

[0042] Exemplary curable phenolic resins include novolac and resole phenolic resins. Novolac phenolic resins are acid catalyzed and characterized by a ratio of formaldehyde to phenol of less than 1, typically 0.5:1 to 0.8:1. Resole phenolic resins are alkali catalyzed and characterized by a ratio of formaldehyde to phenol of 1 or more, typically 1:1 to 3:1. Novolac and resole phenolic resins may be chemically modified (e.g., by reaction with an epoxy compound) or unmodified. Exemplary acid catalysts suitable for curing phenolic resins include sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, and p-toluenesulfonic acid. Alkaline catalysts suitable for curing phenolic resins include sodium hydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide, organic amines, and / or sodium carbonate.

[0043] Examples of commercially available phenolic resins include those known under the trade names DUREZ and VARCUM from Durez Corporation, Novi, Michigan; RESINOX from Monsanto Corp., Saint Louis, Missouri; AROFENE and AROTAP from Ashland Chemical Co., Columbus, Ohio; and RUTAPHEN from Momentive, Columbus, Ohio; and PHENOLITE from Kangnam Chemical Company Ltd., of Seoul, South Korea. Examples of commercially available novolac-type resins include those sold as DUREZ 1364 and VARCUM 29302 from Durez Corporation. Examples of commercially available resole-type phenolic resins include the 29217, 29306, 29318, 29338, and 29353 grades of VARCUM resol; AEROFENE 295; and PHENOLITE TD-2207.

[0044] In some embodiments, the curable binder precursor is a urethane prepolymer. Examples of useful urethane prepolymers include polyisocyanates and their blocked forms. Typically, blocked polyisocyanates do not substantially react with isocyanate-reactive compounds (e.g., amines, alcohols, thiols) under ambient conditions (e.g., at temperatures ranging from about 20°C to about 25°C), but upon application of sufficient thermal energy, the blocking agent is released, thereby generating an isocyanate functional group that reacts with an amine curing agent to form a covalent bond.

[0045] The curable binder composition may contain various additives, such as conventional resin fillers (e.g., calcium carbonate or fine fibers), lubricants (e.g., stearic acid and alkali metal salts of light petroleum), grinding aids (e.g., potassium borofluoride), wetting agents or surfactants (e.g., sodium lauryl sulfate), defoamers, pigments, dyes, biocides, coupling agents (e.g., organosilanes), plasticizers (e.g., polyalkylene polyols or phthalates), thickeners, and combinations thereof. Typically, the curable binder precursor contains at least one solvent (e.g., isopropyl alcohol, methyl ethyl ketone, water) to facilitate coating of the curable binder precursor on the nonwoven fibrous web, but this is not a requirement.

[0046] Examples of useful abrasive particles include any abrasive particles known in the abrasives field.Exemplary examples of useful abrasive particles include fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide material such as that commercially available from 3M Company, St.Paul, Minnesota as 3M CERAMIC ABRASIVE GRAIN, brown aluminum oxide, blue aluminum oxide, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, garnet, titanium carbide, diamond, cubic boron nitride, fused alumina zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery, sol-gel derived ceramic (e.g., alpha alumina), and combinations thereof. Examples of sol-gel derived abrasive particles from which the abrasive particles can be isolated and methods of preparation thereof can be found in U.S. Patents 4,314,827 (Leitheiser et al.), 4,623,364 (Cottringer et al.), 4,744,802 (Schwabel), 4,770,671 (Monroe et al.), and 4,881,951 (Monroe et al.). It is also contemplated that the abrasive particles may include abrasive agglomerates such as those described in U.S. Patents 4,652,275 (Bloecher et al.) and 4,799,939 (Bloecher et al.). In some embodiments, the abrasive particles may be surface treated with a coupling agent (e.g., an organosilane coupling agent) or other physical treatment (e.g., iron oxide or titanium oxide) to enhance adhesion of the abrasive particles to, for example, a phenolic binder.

[0047] The abrasive particles may have an average diameter of, for example, at least about 0.1 micrometer, at least about 1 micrometer, or at least about 10 micrometers, and less than about 2000 micrometers, less than about 1300 micrometers, or less than about 1000 micrometers, although larger and smaller abrasive particles may also be used. For example, the abrasive particles may have a nominal grade specified by the abrasives industry. Such abrasives industry-accepted grading standards include those known as the American National Standards Institute (ANSI) standards, the European Abrasives Manufacturers Association (FEPA) standards, and the Japanese Industrial Standards (JIS) standards. Exemplary ANSI grade designations (i.e., the nominal grades designated) include ANSI4, ANSI6, ANSI8, ANSI16, ANSI24, ANSI36, ANSI40, ANSI50, ANSI60, ANSI80, ANSI100, ANSI120, ANSI150, ANSI180, ANSI220, ANSI240, ANSI280, ANSI320, ANSI360, ANSI400, and ANSI600. Exemplary FEPA grade designations include P8, P12, P16, P24, P36, P40, P50, P60, P80, P100, P120, P150, P180, P220, P320, P400, P500, 600, P800, P1000, and P1200. Exemplary JIS grade designations include HS8, JIS12, JIS16, JIS24, JIS36, JIS46, JIS54, JIS60, JIS80, JIS100, JIS150, JIS180, JIS220, JIS240, JIS280, JIS320, JIS360, JIS400, JIS600, JIS800, JIS1000, JIS1500, JIS2500, JIS4000, JIS6000, JIS8000, and JIS10000.

[0048] The abrasive particles may include sol-gel derived polycrystalline alpha alumina particles. Such abrasive particles composed of alpha alumina, magnesium alumina spinel, and rare earth hexagonal aluminate crystallites can be prepared using sol-gel precursor alpha alumina particles by methods described, for example, in U.S. Pat. No. 5,213,591 (Celikkaya et al.) and U.S. Patent Application Publication Nos. 2009 / 0165394(A1) (Culler et al.) and 2009 / 0169816(A1) (Erickson et al.). Further details regarding methods of making sol-gel derived abrasive particles can be found, for example, in U.S. Pat. Nos. 4,314,827 (Leitheiser), 5,152,917 (Pieper et al.), 5,435,816 (Spurgeon et al.), 5,672,097 (Hoopman et al.), 5,946,991 (Hoopman et al.), 5,975,987 (Hoopman et al.), and 6,129,540 (Hoopman et al.), and U.S. Patent Application Publication No. 2009 / 0165394(A1) (Culler et al.).

[0049] The abrasive particles may include shaped abrasive particles having a triangular platelet shape, for example, as can be found in U.S. Patent Nos. 5,201,916 (Berg), 5,366,523 (Rowenhorst (Re 35,570)), and 5,984,988 (Berg). In some embodiments, the shaped abrasive particles are precision shaped (i.e., they have a shape that is determined at least in part by the shape of the mold cavity of the manufacturing tool used to make them). Details regarding such abrasive particles and methods of preparation thereof can be found, for example, in U.S. Patent Nos. 8,142,531 (Adefris et al.), 8,142,891 (Culler et al.), and 8,142,532 (Erickson et al.), as well as U.S. Patent Application Publication Nos. 2012 / 0227333 (Adefris et al.), 2013 / 0040537 (Schwabel et al.), and 2013 / 0125477 (Adefris). One particularly useful precision shaped abrasive particle shape is that of a platelet having three sidewalls, any of which may be straight or concave and may be perpendicular or inclined relative to the platelet base; for example, as described in U.S. Patent Nos. 9,771,504 and 10,301,518 (both to Adefris).

[0050] In some embodiments, the shaped abrasive particles may be selected to have a length and / or width in the range of 0.1 micrometers to 3.5 millimeters (mm), more typically 0.05 mm to 3.0 mm, and more typically 0.1 mm to 2.6 mm, although other lengths and widths may also be used.

[0051] In some embodiments, the shaped abrasive particles may be selected to have a thickness ranging from 0.1 micrometer to 1.6 mm, more typically from 1 micrometer to 1.2 mm, although other thicknesses may be used. In some embodiments, the abrasive particles may have an aspect ratio (length to thickness) of at least 2, 3, 4, 5, 6, or more.

[0052] Typically, the coating weight of the abrasive particles (independent of the other components in the curable composition) can depend, for example, on the particular curable phenolic resin prepolymer used, the process by which the abrasive particles are applied, and the size of the abrasive particles. For example, the coating weight of the abrasive particles on the nonwoven fibrous web can be at least 200 grams per square meter (g / m), at least 600 g / m, or at least 800 g / m, and / or less than 2000 g / m, less than about 1600 g / m, or less than about 1200 g / m, although greater or lesser coating weights can also be used.

[0053] Typically, an amount of 1120 to 2080 gsm, more typically 1280 to 1920 gsm, and even more typically 1440 to 1760 gsm of the curable abrasive layer precursor composition (including any optional solvent that may be present) is coated onto the nonwoven fibrous web, although values ​​outside these ranges can also be used.

[0054] In the second method, a curable make layer precursor composition containing a phenolic resin is impregnated into a nonwoven fibrous web or otherwise coated (e.g., by roll coating or spray coating) onto at least a portion of the prebond layer, and then the abrasive particles are deposited thereon, for example, by electrostatic coating, drop coating or spray coating.

[0055] In some embodiments according to the present disclosure, the curable make layer precursor composition comprises a polymer having multiple oxazolinyl groups. Useful polymers having multiple oxazolinyl groups can include acrylic polymers, such as methacrylic polymers. Useful (meth)acrylic polymers having multiple oxazolinyl groups can be copolymers of free radically polymerizable oxazoline functional monomers and one or more (meth)acrylic monomers. Exemplary free radically polymerizable oxazoline functional monomers include 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, and various substituted derivatives described in U.S. Pat. No. 3,839,350 (Hunsucker). Additional non-acrylic free radically polymerizable monomers can be included in the (meth)acrylic polymer having multiple oxazolinyl groups. Exemplary such monomers include styrene and substituted styrenes. In some embodiments, the curable make layer precursor composition can comprise the polymer having multiple oxazolinyl groups in an amount of at least 0.5 PHR, 1 PHR, 3 PHR, or 5 PHR.

[0056] In either embodiment, the phenolic resin is at least partially cured after the phenolic resin precursor composition is deposited on the prebond layer and any portion of the nonwoven fibrous web. Typically, the phenolic resin is cured by heating (e.g., in an oven or under heat lamps).

[0057] Optionally, and preferably in the second embodiment, a curable size layer precursor can be applied over the at least partially cured make layer precursor and abrasive particles. The size layer precursor may comprise the same or different binder precursor used in the make layer (if present) and / or the slurry layer (if present). The size layer precursor can comprise, for example, adhesives, phenolic resins, aminoplast resins, urea-formaldehyde resins, melamine-formaldehyde resins, urethane resins, free radically polymerizable multifunctional (meth)acrylates (e.g., aminoplast resins with pendant alpha, beta-unsaturated groups, acrylated urethanes, acrylated epoxies, acrylated isocyanurates), epoxy resins (including bis-maleimide and fluorene modified epoxy resins), isocyanurate resins, and mixtures thereof. In a preferred embodiment, the size layer precursor comprises a curable phenolic resin.

[0058] The size layer precursor can be applied by any known coating method for applying a size layer to a backing, including roll coating, extrusion die coating, curtain coating, knife coating, gravure coating, spray coating, etc. If desired, a presize layer precursor or make layer precursor according to the present disclosure can also be used as the size layer precursor.

[0059] Similarly, the size layer precursor may be cured by heating (eg, in an oven or under heat lamps) or by other methods.

[0060] Depending on the intended use, the type of abrasive particles, and the nature of the coated abrasive article being prepared, the basis weight of the size layer will necessarily vary, but will typically range from 1 or 5 gsm to 300, 400, or even 500 gsm or more. The size layer precursor can be applied by any known coating method for applying a size layer precursor (e.g., a size coat) to a backing, including, for example, roll coating, extrusion die coating, curtain coating, and spray coating.

[0061] Optionally, a supersize layer can be added on at least a portion of the size layer. When present, the supersize typically includes a grinding aid and / or an anti-loading material. The optional supersize layer can serve to prevent or reduce the accumulation of chips (material ground from the workpiece) between the abrasive particles, which can dramatically reduce the cutting ability of the coated abrasive article. Useful supersize layers typically include grinding aids (e.g., potassium tetrafluoroborate), metal salts of fatty acids (e.g., zinc stearate or calcium stearate), salts of phosphate esters (e.g., potassium behenyl phosphate), phosphate esters, urea-formaldehyde resins, mineral oils, crosslinked silanes, crosslinked silicones, and / or fluorochemicals. Useful supersize materials are further described, for example, in U.S. Pat. No. 5,556,437 (Lee et al.).

[0062] Typically, the amount of grinding aid incorporated into a coated abrasive product is from about 50 to about 400 gsm, more typically from about 80 to about 300 gsm. The supersize can contain a binder, such as a binder used to prepare the size layer or make layer, but need not have any binder.

[0063] Exemplary nonwoven abrasive articles comprising a high-loft open nonwoven fiber web include nonwoven abrasive webs used to make hand pads, surface conditioning disks and belts, flap brushes, and integrated or convoluted abrasive wheels. In such nonwoven abrasive articles, the gaps between adjacent fibers are not substantially filled with binder composition and abrasive particles, resulting in a composite structure with a very low density having a network on many relatively large interconnected voids. The resulting lightweight, high-loft, extremely open fibrous structures are essentially non-occlusive and non-filling, especially when used with liquids such as water and oil. These structures are also easily cleaned by simple rinsing with a cleaning liquid, dried, and can be reused after being left for a significant period of time. For this reason, the voids of these nonwoven abrasive articles can constitute at least about 75% of the total space occupied by the composite structure, and preferably more than that.

[0064] The nonwoven abrasive article according to the present disclosure is useful, for example, for abrading a workpiece. For example, a method for abrading a workpiece may include bringing a nonwoven abrasive article according to the present disclosure into frictional contact with a surface of the workpiece, and moving at least one of the nonwoven abrasive articles and the surface of the workpiece relative to the other to abrade at least a portion of the surface of the workpiece.

[0065] Sanding can be done dry or wet. For wet sanding, liquid is introduced and may be dispensed in the form of a light mist to completely submerge. Examples of commonly used liquids include water, water-soluble oils, organic lubricants, and emulsions. The liquid may act to reduce the heat associated with sanding and / or act as a lubricant. The liquid may contain small amounts of additives such as germicides, defoamers, etc.

[0066] Examples of workpieces include aluminum metal, carbon steel, mild steel (e.g., 1018 mild steel and 1045 mild steel), tool steel, stainless steel, hardened steel, titanium, glass, ceramic, wood, wood-like materials (e.g., plywood and particle board), paints, painted surfaces, organic coated surfaces, etc. The force applied during abrasion typically ranges from about 1 to about 100 kilograms (kg), although other pressures may be used.

[0067] Objects and advantages of the present disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the disclosure. EXAMPLES

[0068] All parts, percentages, ratios, etc. in the examples and elsewhere in the specification are by weight unless otherwise stated. Materials used in the examples are reported in Table 1 below. [Table 1]

[0069] Preparation of nonwoven abrasive discs: Examples 1 to 5 and Comparative Examples A and B Nonwoven abrasive discs were prepared according to the following procedure using the amounts reported in Table 2 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was roll coated with the prebond precursor composition, and then the coated nonwoven fiber mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fiber mat was coated with the abrasive mixture solution by spraying and cured in an oven at 150° C. for 5 minutes. [Table 2]

[0070] Examples 6 to 10 and Comparative Example B Nonwoven abrasive discs were prepared according to the following procedure, using the amounts reported in Table 3 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was spray coated with a prebond precursor composition (phenolic resin plus colorant) and then the coated nonwoven fibrous mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fibrous mat was cured at 4.2 g / 100 cm using the composition listed in Table 3. 2 ~4.5g / 100cm 2 The coated nonwoven fiber mat was then cured in a 150° C. oven for 5 minutes. [Table 3]

[0071] Examples 11 to 13 and Comparative Examples C and D Nonwoven abrasive discs were prepared according to the following procedure using the amounts reported in Table 4 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was spray coated with a prebond precursor composition (phenolic resin plus colorant) and then the coated nonwoven fiber mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fiber mat was cured at 3.4 g / 100 cm using the composition listed in Table 4. 2 ~4.4g / 100cm 2 The abrasive slurry was spray coated with an abrasive slurry at an add-on weight of 100g / g. In Comparative Example C, which used a silane coupling agent, the aluminum oxide abrasive grain 1 was mixed with an aqueous silane coupling solution and treated at 90°C (194°F) for 18 hours, and then the silane coupled aluminum oxide abrasive grain was mixed with a phenolic resin. The coated nonwoven fiber mat was cured in a 150°C oven for 5 minutes. [Table 4]

[0072] Examples 14 to 18 and Comparative Example E Nonwoven abrasive discs were prepared according to the following procedure using the amounts reported in Table 5 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was spray coated with a prebond precursor composition (phenolic resin plus colorant) and then the coated nonwoven fibrous mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fibrous mat was cured at 3.8 g / 100 cm using the composition listed in Table 5. 2 ~4.2g / 100cm 2 The coated nonwoven fiber mat was then cured in a 150° C. oven for 5 minutes. [Table 5]

[0073] Examples 19 to 22 and Comparative Example F Nonwoven abrasive discs were prepared according to the following procedure using the amounts reported in Table 6 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was spray coated with a prebond precursor composition (phenolic resin plus colorant) and then the coated nonwoven fibrous mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fibrous mat was cured at 4.1 g / 100 cm using the composition listed in Table 6. 2 ~4.4g / 100cm 2 The coated nonwoven fiber mat was then cured in a 150° C. oven for 5 minutes. [Table 6]

[0074] Examples 23 to 27 and Comparative Example G Nonwoven abrasive discs were prepared according to the following procedure using the amounts reported in Table 7 below: A bulky, open-weave nonwoven fiber mat (polyamide fiber, 17 dtex, basis weight = 1.4 g / 100 cm 2 ~1.6g / 100cm 2 ) was spray coated with a prebond precursor composition (phenolic resin plus colorant) and then the coated nonwoven fibrous mat was cured in an oven at 90° C. for 30 minutes. The prebonded nonwoven fibrous mat was cured at 4.2 g / 100 cm using the composition listed in Table 7. 2 ~4.4g / 100cm 2 The coated nonwoven fiber mat was then cured in a 150° C. oven for 5 minutes. [Table 7]

[0075] SCHIEFER Abrasion Test The resulting nonwoven abrasive mat was cut to a size of 10 cm, thickness: 0.87 cm to 1.06 cm, and a Schiefer abrasion test was performed using a polymethyl methacrylate plate (diameter 10.16 cm, thickness 0.3 cm). The nonwoven abrasive article specimens were prepared as 10 cm diameter disks, which were stacked and then secured to a foam back-up pad by hook-and-loop fasteners. The back-up pad / fastener assembly had a Shore durometer OO hardness of 85. The abrasive disk and back-up pad assembly was mounted on a Schiefer Uniform Abrasion Tester (available from Frazier Precision Instrument Company, Inc. Hagerstown, Maryland), and the abrasive disk was used to abrade a disk of polymethyl methacrylate (PMMA) (diameter 10.16 cm, thickness 0.3 cm) from Mitsubishi Chemical Corporation, Tokyo, Japan. The load was 10 lb (4.5 kg). The test duration was 6000 cycles of the abrasive disk. The amount of PMMA polymer removed was measured at the end of the test.

[0076] Tables 8-13 below report the results of the Schiefer abrasion tests. [Table 8] [Table 9] [Table 10] [Table 11] [Table 12] [Table 13]

[0077] All publications, patents, and patent applications cited in this application are incorporated by reference in a consistent manner. In the event of a conflict or inconsistency between any portion of the incorporated reference and this application, the information in this application shall control.

[0078] The preceding description is intended to enable one skilled in the art to practice the disclosure as set forth in the claims and should not be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereof.

Claims

1. A bulky and open nonwoven fiber web; A nonwoven abrasive article comprising: a prebond composition disposed on at least a portion of the lofty, open-weave nonwoven fibrous web; and an abrasive layer disposed and secured on at least a portion of the prebond composition, the abrasive layer comprising a binder composition that holds abrasive particles; A nonwoven abrasive article, wherein at least one of the prebond composition and the binder composition comprises the reaction product of a polymer having a plurality of oxazolinyl groups.

2. The nonwoven abrasive article of claim 1 , wherein the polymer having multiple oxazolinyl groups comprises an acrylic polymer.

3. 3. The nonwoven abrasive article of claim 1 or 2, wherein the polymer having multiple oxazolinyl groups comprises a methacrylic polymer.

4. The nonwoven abrasive article of any one of claims 1 to 3, wherein the polymer having multiple oxazolinyl groups is at least 1 part per 100 parts of resin (PHR).

5. The nonwoven abrasive article of any one of claims 1 to 4, wherein the polymer having multiple oxazolinyl groups is at least 3 parts per hundred parts of resin (PHR).

6. The nonwoven abrasive article of any one of claims 1 to 5, wherein the prebond composition comprises a reaction product of a polyurethane having multiple carboxyl groups, and on a solids basis, the (meth)acrylic polymer and the polyurethane are present in a weight ratio of 1:99 to 8:

92.

7. The nonwoven abrasive article of claim 6, wherein, on a solids basis, the (meth)acrylic polymer having a plurality of oxazolinyl groups and the polyurethane having a plurality of carboxyl groups are present in a weight ratio of 1:99 to 7:

93.

8. The nonwoven abrasive article of any one of claims 1 to 7, wherein the binder composition comprises a phenolic resin.

9. The nonwoven abrasive article of any one of claims 1 to 8, wherein the nonwoven abrasive article comprises a nonwoven abrasive disc.

10. The nonwoven abrasive article of any one of claims 1 to 9, wherein the lofty, open nonwoven fibrous web comprises polyamide.

11. 1. A method of making a nonwoven abrasive article, comprising: disposing a curable prebond precursor composition on at least a portion of a lofty, open nonwoven fibrous web; at least partially curing the curable prebond precursor composition to provide a prebond composition; disposing an abrasive layer precursor composition over at least a portion of the prebond composition, the abrasive layer precursor composition comprising a phenolic resin and abrasive particles; and at least partially curing the abrasive layer precursor composition, The method, wherein at least one of the curable prebond precursor composition and the abrasive layer precursor composition comprises a polymer having a plurality of oxazolinyl groups.

12. 1. A method of making a nonwoven abrasive article, comprising: disposing a curable prebond precursor composition on at least a portion of a lofty, open nonwoven fibrous web; at least partially curing the curable prebond precursor composition to provide a prebond composition; disposing a curable make layer precursor composition over at least a portion of the prebond composition, the curable make layer precursor composition comprising a phenolic resin; at least partially embedding abrasive particles in said curable make layer precursor composition; at least partially curing the curable make layer precursor composition to provide an at least partially cured make layer composition; The method, wherein at least one of the curable prebond precursor composition and the curable make layer precursor composition comprises a polymer having a plurality of oxazolinyl groups.

13. 13. The method of claim 11 or 12, wherein the polymer having multiple oxazolinyl groups comprises an acrylic polymer.

14. The method of any one of claims 11 to 13, wherein the polymer having multiple oxazolinyl groups is at least 1 part per hundred parts of resin (PHR).

15. 15. The method of any one of claims 11 to 14, wherein the curable prebond precursor composition comprises a polyurethane having multiple carboxyl groups, and on a solids basis, the polymer having multiple oxazolinyl groups and the polyurethane are present in a weight ratio of from 1:99 to 8:

92.

16. The method of claim 15, wherein, on a solids basis, the polymer having multiple oxazolinyl groups and the polyurethane are present in a weight ratio of from 1:99 to 7:

93.

17. disposing a curable size layer precursor composition on the at least partially cured make layer composition; The method of any one of claims 11 to 16, further comprising at least partially curing the curable size layer precursor composition.

18. The method of any one of claims 11 to 17, wherein the nonwoven abrasive article comprises a nonwoven abrasive disc.

19. The method of any one of claims 11 to 18, wherein the lofty, open nonwoven fibrous web comprises a polyamide.

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