JP6000333B2 - Nonwoven abrasive articles containing elastomer-bonded agglomerates of molded abrasive grains - Google Patents

Description

Detailed Description of the Invention

[background]
Nonwoven abrasive articles generally have a nonwoven fibrous web (eg, a bulky and coarse fibrous web), abrasive particles, and a binding material (usually referred to as a “binder”), the binding material being non-woven. The fibers in the woven fiber web are bonded together and the abrasive particles are secured to the fiber web. Examples of non-woven abrasive articles include non-woven abrasive hand pads such as those sold under the trade name “SCOTCH-BRITE” from 3M Company (Saint Paul, Minnesota).

  Other examples of non-woven fabric abrasives include convolution grinding wheels and integrated grinding wheels. Nonwoven grinding wheels typically have abrasive particles distributed through layers of nonwoven fibrous webs that are bonded together by a binder that bonds the layers of nonwoven fibrous webs and also adheres the abrasive particles to the nonwoven fibrous web. Have. The monolithic grinding wheel has individual disks of nonwoven fibrous webs arranged in parallel in a manner that forms a cylinder with a hollow axis. Alternatively, the convolution grinding wheel has a non-woven fibrous web wound spirally around a core member and adhered to the core member.

[Overview]
Cutting of the nonwoven abrasive article and the resulting finish while using the nonwoven abrasive article on the workpiece are important performance attributes. In some applications, it is highly desirable to reduce the resulting surface roughness (finish) of the workpiece while maintaining or even increasing the cutting of the nonwoven abrasive article in use. Surprisingly, it has been found that the nonwoven abrasive articles according to the present invention show a significant improvement in surface finish when evaluated according to the disclosed test methods compared to the alternative nonwoven abrasive articles shown in the examples. It was done.

  Specifically, when forming agglomerates of formed ceramic abrasive particles, it has been found that the use of a flexible binder, such as a polyurethane binder, significantly improves the resulting surface finish of the workpiece. It was done. This discovery was indeed surprising because it was previously thought that the binder for forming the agglomerates did not make a significant contribution to the resulting finish of the nonwoven abrasive article. Until now, when using exactly the same abrasive particle size and amount in each grinding wheel, the resulting surface finish is due to the type of binder (urethane vs. phenolic resin) that binds the nonwoven layers in the grinding wheel. It was something to do. Furthermore, surprisingly, flexible bonded agglomerates of formed abrasive particles have been found to provide a more precise finish than nonwoven abrasive articles made using the exact same formed abrasive particles that are not agglomerated. It was. Previously, agglomerating formed abrasive particles only extended the useful life of the abrasive article, and the resulting finish was thought to be equal to non-aggregated abrasive particles of the same size.

  Accordingly, in one aspect, the present invention provides a nonwoven fibrous web, an agglomerate comprising formed ceramic abrasive particles that are bound by a first flexible binder, and a second that binds the agglomerate to the nonwoven fibrous web. A nonwoven fabric abrasive article comprising a binder.

  Reference signs used repeatedly in the specification and figures are intended to represent the same or similar features or elements of the present disclosure.

The perspective view of the typical nonwoven fabric abrasive article of this invention. 1 is a perspective schematic view of a representative convolution grinding wheel according to one embodiment of the present invention. FIG. FIG. 3 is a perspective schematic view of a representative integrated grinding wheel according to another aspect of the present invention. FIG. 3 is a photomicrograph of one embodiment of an abrasive agglomerate formed from formed abrasive particles. 5 is a photomicrograph of another embodiment of an abrasive agglomerate formed from formed abrasive particles. FIG. 6 is a photomicrograph of another embodiment of an abrasive agglomerate formed from shaped abrasive particles.

[Definition]
As used herein, the variations of the words “comprising”, “having”, and “including” are legally equivalent and not constrained. Thus, in addition to the elements, functions, steps, or restrictions described, there may be additional elements, functions, steps, or restrictions that are not described.

  As used herein, the term “curing” refers to drying (ie, evaporation of the solvent), polymerizing (eg, providing sufficient chain extension of the curable polyurethane prepolymer), or cooling the molten material. Means to cure the substance.

  As used herein, the term "flexible binder" refers to a cured binder material that, unlike a phenolic resin binder that breaks, allows the cured binder material to bend sufficiently without breaking. Means having an elastic modulus. In various embodiments of the present invention, the modulus is less than 28,000 psi (193.05 MPa), or less than 25,000 psi or less than 23,000 psi (less than 172.37 MPa or 158.58 MPa when tested according to ASTM D882. Less). Examples of suitable flexible binders include polyurethane, polyurea, polyisoprene, polybutadiene, polychloroprene, butyl rubber, styrene butadiene copolymer, and nitrile rubber binders.

  As used herein, the term “formed ceramic abrasive particles” refers to abrasive particles having an at least partially replicated shape. A non-limiting process for producing shaped abrasive particles includes forming a precursor ceramic abrasive particle in a mold having a predetermined shape to produce the shaped ceramic abrasive particle, having a predetermined shape. Extruding the precursor ceramic abrasive particles through an orifice, printing the precursor ceramic abrasive particles through an opening in a printing screen having a predetermined shape, or embossing the precursor ceramic abrasive particles into a predetermined shape or pattern. Including. Non-limiting examples of formed ceramic abrasive particles include: US Reissue Patent Nos. 35,570; 5,201,916, and 5,984,998; National Patent Application Publication No. 2009/0169816. 2009/0165394, 2010/0151195, 2010/0151201, 2010/0146867; 2010/0151196, and 2010/0319269. , Molded ceramic abrasive particles such as triangular plates, or elongated ceramic rods / fibers often having a circular cross-section, such as those disclosed in US Pat. No. 5,372,620, manufactured by Saint-Gobain Abrasives. Can be mentioned.

  As used herein, the term “inorganic” means abrasive particles or a mixture of abrasive particles and filler.

[Detailed description]
Various representative abrasive articles according to the present invention, including bulky and coarse nonwoven abrasive articles (eg, webs and sheets), monolithic grinding wheels, and convolution grinding wheels, for example, on nonwoven fiber webs, It can be manufactured through a process that includes steps such as coating a curable composition, typically in slurry form. The curable composition comprises a curable polyurethane prepolymer, an effective amount of an amine curing agent, at least one cationic surfactant, an anionic surfactant, a fluorinated nonionic surfactant, or a non-silicone-based surfactant. Contains an ionic surfactant and a bipodal aminosilane. In the formation of convoluted or monolithic grinding wheels, nonwoven fibrous webs are typically compressed (ie densified) as compared to nonwoven fibrous webs used in bulky and coarse nonwoven fibrous articles. Has been.

Nonwoven Fibrous Web Nonwoven fibrous webs suitable for use in the aforementioned abrasive articles are well known in the abrasive art. Typically, a nonwoven web comprises a web of entangled fibers. The fibers may include continuous fibers, short fibers, or combinations thereof. For example, the nonwoven fibrous web may comprise 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. Shorter fibers and longer fibers (eg, continuous fibers) may also be useful. The fibers may have a fineness or linear density of at least about 1.7 dtex (ie, g / 10000 m), 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. However, fibers having smaller and / or higher linear densities may be useful. Mixtures of fibers having different linear densities may also be useful, for example, to provide an abrasive article that provides a particularly favorable surface finish when in use. When using a spunbond nonwoven, the filaments can be substantially larger in diameter, for example, 2 mm or less in diameter or more.

  Nonwoven webs can be made, for example, by conventional airlaid, carded, stitchbonded, spunbonded, wet laid, and / or meltblown procedures. The airlaid nonwoven fibrous web can be prepared using equipment such as that available from Rando Machine Company (Macedon, New York) under the trade name “RANDO WEBBER”.

  The nonwoven fibrous web is typically selected to be suitable for adhesion between the binder and abrasive particles while being processable in combination with other components of the article, typically curable. It can withstand processing conditions (eg, temperature) such as those used during application and curing of the composition. The fibers can be selected to affect the properties of the abrasive article, such as, for example, flexibility, elasticity, durability or service life, abrasion, and finish characteristics. Examples of fibers that may be suitable include natural fibers, synthetic fibers, and mixtures of natural and / or synthetic fibers. Examples of synthetic fibers include polyester (eg, polyethylene terephthalate), nylon (eg, hexamethylene adipamide, polycaprolactam), polypropylene, acrylonitrile (ie, acrylic), rayon, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymer And those made from vinyl chloride-acrylonitrile copolymers. Examples of suitable natural fibers include cotton, wool, jute, and linen. The fibers may be virgin material or, for example, recovered material or waste material regenerated from cutting, carpet manufacturing, fiber manufacturing, or fiber processing. The fibers can be homogeneous or can be composites such as bicomponent fibers (eg, co-spun core-sheath fibers). The fibers may be stretched and crimped, but may also be continuous filaments such as those formed by an extrusion process. A combination of fibers may be used.

  Prior to impregnation with the curable composition, the nonwoven fibrous web is typically at least about 50 grams per square meter (as measured prior to any coating (eg, with the curable composition or any prebond resin)). gsm), at least about 100 gsm, or at least about 200 gsm, and / or less than about 400 gsm, less than about 350 gsm, or less than about 300 gsm, but with a larger basis weight and smaller basis weight You may use the thing of quantity. Further, prior to impregnation with the curable composition, the fibrous web is typically at least about 5 mm, at least about 6 mm, or at least about 10 mm, and / or less than about 200 mm, less than about 75 mm, or less than about 30 mm. Although having a thickness, thicker and thinner ones may also be useful.

  Further details regarding non-woven abrasive articles, grinding wheels and methods of making them can be found, for example, in US Pat. Nos. 2,958,593 (Hoover et al.), 5,591,239 (Larson et al.), No. 6,017,831 (Beardsley et al.) And US Patent Application Publication No. 2006/0041065 A 1 (Barber, Jr.).

  Often it is useful to apply a prebond resin to the nonwoven fibrous web prior to coating with the curable composition. The prebond resin, for example, helps to maintain the integrity of the nonwoven web during handling and can also promote adhesion of the urethane binder to the nonwoven web. Examples of the prebond resin include phenol resin, urethane resin, glue, acrylic resin, urea formaldehyde resin, melamine formaldehyde resin, epoxy resin, and combinations thereof. The amount of the prebond resin used in this method is typically adjusted to a minimum amount suitable for bonding fibers at a cross-linking contact. If the nonwoven web includes thermally adhesive fibers, thermal bonding of the nonwoven web can also help maintain the integrity of the web being processed.

Abrasive Particles Abrasive particles useful for incorporation into the agglomerates of the present invention are formed ceramic abrasive particles, particularly shaped ceramic abrasive particles. Molded ceramic abrasive particles were prepared according to the disclosure of co-pending US Patent Publication No. 2010/0151196. The molded ceramic abrasive particles are made of, for example, alumina sol gel from a mold hole of an equilateral triangle shaped polypropylene mold having a side length of 0.054 inch (1.37 mm) and a mold depth of 0.012 inch (0.3 mm). Prepared by molding. After drying and firing, the resulting shaped ceramic abrasive particles comprised a triangular plate, which was about 570 micrometers (longest dimension) and passed through a 30 mesh screen.

  The articles of the present invention may also contain conventional (eg, crushed) abrasive particles in addition to the shaped ceramic abrasive particles. Examples of conventional abrasive particles useful for blending with shaped ceramic abrasive particles include any abrasive particles known in the abrasive art. Typical useful abrasive particles include aluminum oxide, ceramic aluminum oxide (which may include one or more metal oxide modifiers and / or seeds or nucleating agents), and heat treated aluminum oxide. Fused aluminum oxide materials, silicon carbide, co-fused alumina-zirconia, diamond, ceria, titanium diboride, cubic boron nitride, boron carbide, garnet, flint, emery, sol-gel derived abrasive particles, and these A mixture is mentioned. The abrasive particles may be in the form of, for example, individual particles, agglomerates, composite particles, and mixtures thereof.

  Conventional abrasive particles 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, less than about 1300 micrometers, or less than about 1000 micrometers. Although larger, smaller and smaller abrasive particles may be used. For example, conventional abrasive particles may have a nominal grade specified by the abrasive industry. Such grade classification standards recognized in the abrasive industry include those known as American Standards Association (ANSI) standards, European Abrasive Manufacturing Association (FEPA) standards, and Japanese Industrial Standards (JIS) standards. It is done. Typical ANSI grade designations (ie, designated as nominal grades) include ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36, ANSI 40, ANSI 50, ANSI 60, ANSI 80, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, and ANSI 600. Typical FEPA grades include P8, P12, P16, P24, P36, P40, P50, P60, P80, P100, P120, P150, P180, P220, P320, P400, P500, 600, P800, P1000, and P1200 is mentioned. As representative JIS grades, 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.

Abrasive particle agglomerates The agglomerates of the present invention comprise a first flexible binder. Examples of suitable flexible binders include those of polyurethane, polyurea, polyisoprene, polybutadiene, polychloroprene, butyl rubber, styrene butadiene copolymer, and nitrile rubber.

  A typical flexible binder for the formation of agglomerates comprising formed ceramic abrasive particles is a polyurethane binder. Examples of useful urethane prepolymers include polyisocyanates and their blocked forms. Typically, blocked polyisocyanates are synthesized under ambient conditions (eg, at a temperature in the range of about 20 ° C. to about 25 ° C.) with isocyanate reactive compounds (eg, amines, alcohols, thiols, etc.). ), But upon application of sufficient thermal energy, the blocking agent is released, thereby reacting with the amine curing agent to produce an isocyanate functional group that forms a covalent bond.

  Useful polyisocyanates include, for example, aliphatic polyisocyanates (eg, hexamethylene diisocyanate or trimethylhexamethylene diisocyanate), alicyclic polyisocyanates (eg, hydrogenated xylene diisocyanate or isophorone diisocyanate), and aromatic polyisocyanates. (Eg, tolylene diisocyanate or 4,4′-diphenylmethane diisocyanate), polyhydric alcohol adducts of any of the aforementioned polyisocyanates (eg, diols, polyester resins containing low molecular weight hydroxy groups, water, etc.), as described above. And adducts of polyisocyanates (for example, isocyanates and biurets) and mixtures thereof.

  Useful commercially available polyisocyanates include, for example, those available under the trade name “ADIPRENE” from Chemtura Corporation (Middlebury, Connecticut) (for example, “ADIPRENE L 0311”, “ADIPRENE L 100”, “ADIPRENE L 167”). , "ADIPRENE L 213", "ADIPRENE L 315", "ADIPRENE L 680", "ADIPRENE LF 1800A", "ADIPRENE LF 600D", "ADIPRENE LFP 1950A", "ADIPRENE LFP 5050", "ADIPRENE LFP 50" ADIPRENE LW 520 "and" ADIPREN PP 1095 ") Polyisocyanates (for example, “MONDUR 1437”, “MONDUR MP-095”, or “MONDUR 448”) available from Bayer Corporation (Pittsburgh, Pennsylvania) under the trade name “MONDUR”, and Air Products Cul. Polyisocyanates available from Pennsylvania under the trade designations “AIRTHANE” and “VERSATHANE” (for example, “AIRTHANE APC-504”, “AIRTHANE PST-95A”, “AIRTHANE PST-85A”, “AIRTHANE PET-91A”, "AIRTHANE PET-75D", "VERSATHANE ST E-95A "," VERSATHANE STE-P95 "," VERSATHANE STS-55 "," VERSATHANE SME-90A ", and" VERSATHANE MS-90A ").

  To extend pot life, polyisocyanates such as those described above can be blocked with blocking agents according to various techniques known in the art. Typical blocking agents include ketoximes (eg 2-butanone oxime), lactams (eg ε-caprolactam), malonic esters (eg dimethyl malonate and diethyl malonate), pyrazoles (eg 3 , 5-dimethylpyrazole), tertiary alcohols (eg, t-butanol or 2,2-dimethylpentanol), phenolic resins (eg, alkylated phenolic resins), and alcohols including mixtures of the alcohols described. Can be mentioned.

  Representative useful commercially available blocked polyisocyanates include the blocked polyisocyanates sold under the trade names “ADIPREN BL 11”, “ADIPREN BL 16”, “ADIPREN BL 31” by Chemtura Corporation. , And Baxen Chemicals, Ltd (Accrington, England) under the trade name "TRIXENE" (eg "TRIXENE BL 7641", "TRIXENE BL 7642", "TRIXENE BL 7772", and "TRIXENE BL 7774"). Polyisocyanates prepared.

  Typically, the amount of urethane prepolymer present in the curable composition is 10-40% by weight, more typically 15-30% by weight, and even more typically, based on the total weight of the curable composition. Specifically, it is 20 to 25% by weight, but an amount outside these ranges may be used.

  Suitable amine curing agents include aromatic, alkyl-aromatic, or alkyl multifunctional amines, preferably primary amines. Examples of useful amine curing agents include 4,4′-methylenedianiline, trade name “CURITHANE 103” commercially available from Dow Chemical Company and “MDA-85 commercially available from Bayer Corporation (Pittsburgh, Pennsylvania). A polymeric methylenedianiline having 1,2 to 4.0 functional groups, including those known as, 1,5-diamine-2-methylpentane, tris (2-aminoethyl) amine, 3- Aminomethyl-3,5,5-trimethylcyclohexylamine (ie, isophoronediamine), trimethylene glycol di-p-aminobenzoate, bis (o-aminophenylthio) ethane, 4,4′-methylenebis (dimethylanthranilate) ) (4-amino-3-ethylphenyl) methane (for example, as sold under the trade name “KAYAHARD AA” by Nippon Kayaku Co., Ltd., Tokyo, Japan) and bis (4-amino-3,5 -Diethylphenyl) methane (such as that sold by Lonza, Ltd. (Basel, Switzerland) as "LONZACURE M-DEA"). If desired, the polyol (s) can be added to the curable composition to alter (eg, delay) the cure rate, for example, depending on the needs of the intended application.

  The amine curing agent should be present in an amount effective to cure the polyisocyanate blocked to the extent required for the intended application (ie, an effective amount), for example, the amine curing agent is a curing agent. And the isocyanate (or blocked isocyanate) stoichiometric ratio is in the range of 0.8 to 1.35, such as 0.85 to 1.20, or 0.90 to 0.95. However, stoichiometric ratios outside these ranges can also be used.

  Typically, the curable composition includes at least one organic solvent (eg, isopropyl alcohol or methyl ethyl ketone) to facilitate coating of the curable composition on the nonwoven fibrous web, although this is not required. Absent. If desired, the curable composition may be mixed with one or more additives and / or the curable composition may contain one or more additives. Typical additives include fillers, plasticizers, surfactants, lubricants, colorants (eg, pigments), bactericides, fungicides, grinding aids, and antistatic agents. Typically, a curable composition in an amount of 1120-2080 gsm, more typically 1280-1920 gsm, and even more typically 1440-1760 gsm (including any solvent that may be present) on the nonwoven fibrous web. ) Are coated, but values outside these ranges can also be used.

  Filler materials other than conventional abrasive particles can be blended with the shaped ceramic abrasive particles in the agglomerates of the present invention. Examples of fillers useful in the present invention include metal carbonates (eg, calcium carbonate, calcium magnesium carbonate, sodium carbonate, magnesium carbonate, etc.), silica (eg, quartz, glass beads, glass spheres, glass fibers, etc.) Silicates (eg talc, clay, montmorillonite, feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate, etc.), metal sulfates (eg calcium sulfate, barium sulfate, sodium sulfate, sodium sulfate) Aluminum, aluminum sulfate, etc.), gypsum, vermiculite, sugar, wood powder, trihydrated alumina, carbon black, metal oxides (eg, calcium oxide, aluminum oxide, tin oxide, titanium dioxide, etc.), metal sulfites (eg, sulfurous acid) Calcium etc.) Thermoplastic particles (eg, polycarbonate, polyetherimide, polyester, polyethylene, poly (vinyl chloride), polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polymer, polyurethane, nylon particles, etc.), and thermosetting Particles (for example, phenol resin bubbles, phenol resin beads, polyurethane foam particles, etc.) can be mentioned. The filler may be a salt such as a halide salt. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluoride, potassium chloride, and magnesium chloride. Examples of metal fillers include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Other miscellaneous fillers include sulfur, organic sulfur compounds, graphite, lithium stearate, and metal sulfides.

  For best results, the size of the agglomerates should be 0.8 mm to 5 mm, or 1.4 mm to 4 mm, or 1.8 to 3 mm maximum diameter (if approximately spherical) or maximum side length (approximately cylindrical) Shape, oval, or other geometric shape), and can be spherical, oval, cylindrical, pyramidal, conical, or any polyhedral Platonic solid (tetrahedron, octahedron, etc.) May be. In order to obtain the best results, the ratio of the shaped abrasive particle size (measured side length of the shaped abrasive particle) divided by the aggregate size (measured the maximum diameter or maximum side length of the aggregate) 0.5 (about 300-2 shaped abrasive particles across the agglomerate), or 0.01-0.33 (about 100-3 shaped abrasive particles across the agglomerate), or 0.05-0.25 ( About 20-4 shaped abrasive particles across the agglomerate). For best results, when filler particles (conventional crushed abrasive particles or diluents) are used, the filler particles have an average particle size that is smaller than the size of the formed ceramic abrasive particles, or the filler particle size (maximum diameter) ) Divided by the shaped abrasive particle size (measuring the maximum diameter or maximum side length of the agglomerates) is 0.001-1.0, or 0.003-0.5, or 0.01-0. 1. An exemplary agglomerate of the present invention comprises a first flexible binder of 30 weight percent (wt%) or less, a first flexible binder of 20 wt% or less, a first flexible binder of 15 wt% or less. Or even 10% by weight or less of the first flexible binder. A typical inventive agglomerate comprises at least 50% by weight formed ceramic abrasive particles. For best results, the formed ceramic abrasive particle content is 50 wt% to 98 wt%, 75 wt% to 96 wt%, or 80 wt% to 94 wt%, and the resin content is 2 wt% % To 20 wt%, 4 wt% to 10 wt%, or 5 wt% to 8 wt%, and the filler particle content is 0 wt% to 40 wt%, 10 wt% to 35 wt%, or 15 wt% % To 30% by weight. It will be appreciated that the above ranges for various properties can be combined or selected in any way to identify the nature of the agglomerates.

Nonwoven Abrasive Web A nonwoven abrasive web is made by adhering the agglomerates of the present invention to a nonwoven fibrous web with a curable second binder. Typically, the coating weight of the abrasive agglomerates (independent of the other components in the curable composition) is, for example, the specific second binder used, the process of applying the abrasive agglomerates, and the polishing It may depend on the size of the agglomerates. For example, the coating weight of the abrasive agglomerate on the nonwoven web (before any compression) is at least 200 g / square meter (g / m), at least 600 g / m, or at least 800 g / m, and / or less than 2000 g / m, It may be less than about 1600 g / m, or less than about 1200 g / m, although heavier or lighter coating weights can also be used.

  Second binders useful for adhering the agglomerates to the nonwoven fibrous web are known in the art and are selected according to the requirements of the final product. Typical binders include polyurethanes, phenolic resins, acrylates, and those containing blends of phenolic resins and acrylates. Polyurethane binder materials and their precursors useful for adhering the agglomerates to the nonwoven fibrous web are described herein above.

  Phenolic materials are useful binder precursors because of their thermal properties, availability, cost, and ease of handling. The resole phenolic resin has a molar ratio of formaldehyde to phenol of 1 or more, typically 1.5: 1.0 to 3.0: 1.0. The novolac phenolic resin has a molar ratio of formaldehyde to phenol of less than 1.0: 1.0. Examples of commercially available phenolic resins include Occidental Chemicals Corp. DUREZ and VARCUM manufactured by Monsanto, Resinox manufactured by Monsanto, Ashland Chemical Co. Manufactured by AROFENE, Ashland Chemical Co. What is known by the product name of AROTAP made by the company is mentioned.

  An emulsion of crosslinked acrylic resin particles can also find utility in the present invention.

  Some binder precursors include a phenolic resin mixed with latex. Examples of such latexes include materials including acrylonitrile butadiene, acrylic, butadiene, butadiene-styrene, and combinations thereof. These latices are commercially available from a wide variety of sources, such as those available from Rohm and Haas Company under the trade names RHOPLEX and ACRYLSOL, and Air Products & Chemicals Inc. under the trade names FLEXCRYL and VALTAC. Commercially available under the trade names of SYNTHEMUL, TYCRYL, and TYLAC. Commercially available from B. under the trade names HYCAR and GOODRITE. F. A product commercially available from Goodrich, under the trade name CHEMIGUM, Goodyear Tire and Rubber Co. That are commercially available from ICI under the trade name NEOCRYL, those that are commercially available from BASF under the trade name BUTAFON, and those that are commercially available from Union Carbide under the trade name RES. It is done.

Nonwoven Abrasive Article The nonwoven abrasive article of the present invention may be in any of a variety of conventional forms. FIG. 1 includes a nonwoven fibrous web, an agglomerate comprising formed ceramic abrasive particles bonded by a first flexible binder, and a second binder that bonds the agglomerate to the nonwoven fibrous web. A nonwoven abrasive article 100 is shown. 4-6 show an abrasive agglomerate comprising shaped ceramic abrasive particles and a first flexible binder. As can be seen, the shaped ceramic abrasive particles comprise a triangular plate.

  A preferred nonwoven abrasive article is in the form of a grinding wheel. Non-woven grinding wheels are typically very small (eg, a cylinder height of a few millimeters) or very large (eg, 1 meter or more), and very small ( For example, in the form of a disc or right cylinder having a diameter that may be several centimeters) or very large (eg several tens of centimeters). The grinding wheel typically has a central opening for support by a suitable shaft or other mechanical holding means to allow the grinding wheel to rotate during use. Grinding wheel dimensions, configurations, support means, and rotation means are all well known in the art.

  A spiral grinding wheel tensions a nonwoven fibrous web impregnated with a curable composition around a core member (eg, a tubular or rod-shaped core member) so that the impregnated nonwoven layer is in a compressed state. In order to provide a polyurethane binder that wraps under and then bonds the abrasive agglomerates to the layered nonwoven fibrous web and bonds the layers of the layered nonwoven fibrous web together, It can be provided by curing. A representative convolution grinding wheel 200 is shown in FIG. 2, in which a lamellar coated with a binder that bonds the abrasive agglomerates to the layered nonwoven fibrous web and bonds the layers of the layered nonwoven fibrous web together. The non-woven fibrous web 210 is arranged in a spiral around the core member 230 and is adhered to the core member 230. If desired, the convolution grinding wheel may be reworked before use to remove surface irregularities using, for example, methods known in the abrasive field.

  A representative monolithic grinding wheel is shown in FIG. 3, which, for example, stratifies the impregnated nonwoven fibrous web 310 (eg, as a layered continuous web or sheet stack), Provided by stamping the resulting abrasive article to compress the nonwoven fiber layer, cure the curable composition (eg, using heat), and provide an integral grinding wheel having a hollow axle 320 can do. When compressing a layer of impregnated nonwoven fibrous web, the layer is typically compressed to form a bun having a density of 1 to 20 times the density of the uncompressed layer. The bun is then typically thermoformed (eg, 2-20 hours) at an elevated temperature (eg, 135 ° C.), depending on the urethane prepolymer and the size of the bun.

  The objects and advantages of this disclosure are further illustrated by the following non-limiting examples. The particular materials and amounts recited in these examples, as well as other conditions and details, should not be construed to unduly limit the present disclosure. Unless otherwise noted, all parts, percentages, and ratios in the examples and the rest of the specification are by weight.

The following abbreviations are used throughout the examples.

Preparation of agglomerate binders Solutions containing agglomerated binders for the examples were prepared by mixing the components described below.

  Binder AR1 was 72.3% BL16, 26.8% K-450S, and 0.9% D-1122.

  Binder AR2 was 63.9% phenolic resin, 27.7% tap water, 7.8% SR511, and 0.6% D-1122.

  Binder AR3 was a free radical curable resin selected from 87% acrylic 1 to acrylic 7 and 13% initiator S.

  Binder AR4 was 61.4% BL16, 22.7% K4-450S, 15.3% PMA, and 0.6% D-1122.

Agglomerate Formation The agglomerate precursor composition comprised inorganic material (abrasive particles with optional fillers) and a binder that were manually mixed using a spatula. The agglomerates formed using AR1, AR2, and AR4 were 94 wt% inorganic based on solids. The agglomerates formed using AR3 were 90 wt% inorganic based on solids.

Method 1
Using a stainless steel putty knife, the agglomerate precursor composition was pushed into the mold cavity of a 15 cm × 86 cm sheet of a finely replicated polypropylene mold. The total thickness of the mold is 2.2mm, with 4.0mm square and 1.6mm deep micro-replicated mold cavities separated by a 1.5mm thick wall. did. The mold was made from the corresponding master roll generally following the procedure of US Pat. No. 6,076,248 (Hoopman et al.).

  In order to cure the agglomerates, the filled polypropylene mold sheets were heated in a forced air oven. The urethane agglomerates were cured at 260 ° F. (127 ° C.) for 20 minutes. The phenolic resin agglomerates were cured at 200 ° F. (91 ° C.) for 90 minutes and then at 215 ° F. (102 ° C.) for 16 hours. Agglomerates containing free radical curable resin were cured at 280 ° F. (138 ° C.) for 30 minutes. The cured agglomerate was removed from the mold by ultrasonic energy. More specifically, the back side of the mold was pulled under tension against the front edge of an ultrasonic horn tapering towards a single end. The horn vibrated with an amplitude of about 130 micrometers at a frequency of 19,100 Hz. The horn contained 6-4 titanium and was driven by a 900 watt 184V Branson output source coupled to a 2: 1 Booster 802 piezoelectric transducer. An example of the resulting abrasive agglomerate is shown in FIG.

Method 2
3000 grams of abrasive particles were thoroughly mixed with 250 grams of AR1 to prepare a friable and sticky agglomerate precursor composition. This agglomerate precursor composition was processed into abrasive agglomerate particles using a crusher obtained under the trade name “QUADRO COMIL” (“Model No. 197”, Quadro Engineering Incorporated, Waterloo, Ontario, Canada). Details of the operation of the crusher can be found in PCT International Publication No. WO 02/32832 A1 granted to Culler et al. This premix was extruded through a 75 mil (1.9 mm) circular opening in a conical screen using an impeller driven at 50-3500 rpm. When the critical length is reached, the agglomerate precursor particles formed in the form of filaments are separated by gravity and fall toward the aluminum collection tray. After the precursor particle monolayer or bilayer was collected in a dish, it was placed in an oven set at 320 ° F. (160 ° C.) for 15 minutes to cure the binder resin. After cooling to room temperature, the abrasive agglomerated particles are passed once through a crusher ("QUADRO COMILL") equipped with a 95 mil (2.4 mm) round perforated conical screen. Reduced the size of The reduced size particles were screened with a 14 mesh (1400 micrometer) screen. Using these particles remaining on the screen, an integrated grinding wheel was produced. An example of an abrasive agglomerate is shown in FIG.

Method 3
A few drops of AR4 were applied to an inorganic bed having a thickness of 1-2 cm to form abrasive grains or agglomerates of abrasive grains and filler. The droplets were created by feeding the solution into a non-pointed 22 gauge hypodermic needle supported in a vertical position approximately 7 cm above the inorganic layer. The resin droplets infiltrated into the inorganic layer within 10 seconds after application and wetted an amount of material depending on the surface area of the inorganic or inorganic / filler blend. The agglomerates were cured at 302 ° F. (150 ° C.) for 30 minutes and then screened with non-agglomerated minerals, which were returned to the agglomerate formation process and recycled. Alternatively, AR2 is dripped onto the inorganic or inorganic / filler layer in a similar manner and cured at 200 ° F. (91 ° C.) for 90 minutes, followed by 215 ° F. (102 ° C.) for 16 hours. Cured. The individual agglomerates weighed 0.033 and 0.076 grams and contained 12-4% resin by weight. An example of the resulting abrasive agglomerate is shown in FIG.

Preparation of an Integrated Grinding Wheel A nonwoven web was molded on an airlaid fiber web molding machine available from Rando Machine Corporation (Macedon, New York) under the trade name "RANDO-WEBBER". Fiber webs are available from 70 denier nylon crimp set fibers (EI du Pont de Nemours & Company (Wilmington, Delaware) with staple lengths of 1 inch and 1/2 inch (25.4 mm and 12.7 mm). Possible). The web weighed about 105 g / square meter (gsm) and the thickness was about 0.4 inches (10 mm). The web was conveyed to a horizontal two roll applicator where the prebond resin was applied at a wet add-on weight of 89 gsm. The prebond resin had the following composition (all percentages based on component weight): 54.1% BL16, 19.9% K450S, 26% PMA. Prebonded resin is cured to a non-tacky condition by passing the coated web through a convection oven for 4.5 minutes at 330 ° F. (166 ° C.) and is a pre-adhered nonwoven having a thickness of about 6 mm and a basis weight of 168 gsm. A fiber web was obtained.

  An integral grinding wheel was prepared from a pre-bonded nonwoven web as follows. A 9 inch (23 cm) square section was cut from a prebonded nonwoven fibrous web and saturated with one of two types of grinding wheel adhesives. Grinding wheel adhesive 1 (WA1) is 44% BL16, 16.4% K-450S, 15.8% PMA, 7% MP-22VF, 6% phenoxy, 9.9% kaolin. , And 0.4% D-1122. Grinding wheel adhesive 2 (WA2) was 60.8% phenolic resin, 31.2% water 7.4% SR511, and 0.6% D-1122. The saturated, prebonded web is then passed through the nip of a roll applicator having a 4 inch (10 cm) diameter rubber roll of 85 Shore A durometer hardness and 0.49 ± 0.035 ounces (14 ± 1 g (14 ± 1 g (14)) 14.5 ± 1.03 mL)) or 0.60 ± 0.035 oz (17 ± 1 g (17.7 ± 1.03 mL)) for WA2 Excess resin was removed until the desired resin add-on weight was obtained. Typically, to reach the target weight, it is necessary to pass the nip multiple times at 11 fpm (3.35 mpm (0.06 m / s)) under a pressure of 10-21 psi (69-145 kPa). there were. For each grinding wheel, seven pieces of prebonded web were coated by the above method. The pre-bonded web coated sections were placed in a forced air oven set at 260 ° F. (127 ° C.) for 1 minute to remove most of the solvent. To form a single, non-woven abrasive monolithic slab, 6 pre-bonded sections were each covered with 42 grams of randomly, uniformly distributed minerals or mineral agglomerates. The six coated sections were then stacked and covered with a prebonded seventh section. Next, a release liner was applied to the top and bottom surfaces of the stack before entering the hydraulic heated platen press. A pressure of 5,000 psi (34.5 MPa) was applied to the platen. The uniform thickness of the integrated slab was maintained by placing a 0.25 inch (0.635 cm) thick metal spacer at each corner of the platen. The stack containing WA1 (urethane) was left in a press set at 260 ° F. (127 ° C.) for 30 minutes. The stack containing WA2 (phenolic resin) was left in the press set at 200 ° F. (93 ° C.) for 5 hours. When the press was opened, the web pieces were fused into a single integrated slab. The slab was then placed in a forced air oven set at 260 ° F. (127 ° C.) for 2 hours (WA1) or 215 ° F. (102 ° C.) for 6 hours (WA2). After removal from the oven, the slab was allowed to cool to room temperature, and Deutsche Vereinigte Schuhmaschinen GmbH & Co. Using an SAMCO SB-25 swing beam press manufactured by (Frankfurt, Germany), a 8.0 inch (20 cm) diameter integrated grinding wheel with a 1.25 inch (3.2 cm) center hole is slabbed. Punched from.

Integrated Grinding Wheel Performance Test A pre-weighed 0.25 inch (6.4 mm) monolithic grinding wheel to be tested has a surface speed at the edge of the grinding wheel of about 3500 feet (1065 meters) per minute. It was mounted in a vertical orientation on the axis of a mechanically driven transmission lathe that was adjusted to be. Edge of a 2 inch x 11 inch (5.08 cm x 27.9 cm) cold rolled carbon steel or T304 stainless steel panel with a thickness of 0.0625 inch (1.59 mm) held horizontally at the height of the shaft Was pushed into the rotating edge of the grinding wheel for 20 seconds with a force of about 5 pounds (22.2 Newtons). The amount of material removed from the panel during the test procedure was referred to as “cut” and was defined as the difference in the weight of the panel before and after the test procedure. The amount of material removed from the grinding wheel during the test procedure was called “wear” and was defined as the difference in weight of the grinding wheel before and after the test procedure.

Finishing test of the integrated grinding wheel Place a 6.4 mm thick grinding wheel on the back stand and adjust the speed so that the surface speed is about 3500 feet (1065 meters) per minute. Produced. A 0.0625 inch (1.59 mm) thick 2 inch x 11 inch (5.08 cm x 27.94 cm) cold-rolled carbon steel or T304 stainless steel panel face with a pressure of about 5 pounds (22.2 Newtons). Polishing while adding. The panel is passed 8 times over the grinding wheel, advanced about 0.25 inches (6.4 mm) between each pass, and moved about 2 inches (5.04 cm) per second to produce a length of 4 inches ( A panel of 10.2 cm) was finished. The finish was measured using a Perometer PRK surface meter (Feinprof GmbH; Gottingen, Germany). Ten measurements were taken on each surface. High and low values were ignored and the remaining 8 data points were averaged.

Measurement of resin modulus Modulus measurement by placing 16 grams of AR1 on a circular stainless steel mold with a diameter of 5.5 inches (14 cm) and a side wall height of 0.12 inches (3 mm). Films for use were prepared. To eliminate most of the solvent, the sample was placed in a forced air oven set at 180 ° F. (82 ° C.) for 1 hour. The oven was then set to 260 ° F. (127 ° C.) for 2 hours to complete the cure. The resulting film, about 0.027 inch (0.69 mm) thick, was removed from the steel formwork. A 1 inch x 4 inch (2.54 cm x 10.2 cm) sample was cut from the film and equipped with an MTS Model QTest equipped with an Advantage ™ 2000 N capacity pneumatic sample grip available from MTS Systems Corporation (Eden Prairie, Minnesota). Measurements were made according to ASTM D882-10 “Standard Test Methods for Tensile Properties of Thin Plastic Sheeting” using an Elite 100 tensile tester.

Examples 1 to 3 and Comparative Examples A to L
A urethane bonded integral grinding wheel was made using the components listed in Table 1 according to the procedure described above in the section on agglomerate formation and integral grinding wheel preparation. This integrated grinding wheel was tested according to the integrated grinding wheel performance test and the finishing test of the integrated grinding wheel. The results are shown in Table 2. For Comparative Examples GL, the cutting and wear data were not collected because the abrasive particle size was small and the amount of cutting was very small. Comparative Examples G-L are presented to show the comparison of the finishes obtained.

  The result is that in a non-woven grinding wheel that is flexible (bonded with urethane), the molded ceramic abrasive grains are aggregated with a flexible binder (urethane) and are not aggregated and have the same shape. It shows that it produces a more precise finish compared to. Furthermore, standard crushed particles of similar particle size result in a rougher finish when agglomerated with the same urethane binder, whether ceramic or aluminum oxide. All abrasive particles tested gave a rougher finish when aggregated with a rigid binder (phenolic resin) compared to their non-agglomerated controls. Finally, the agglomerated shaped ceramic abrasive particles provided further performance improvements (cutting and wear) required for the aggregate abrasive particles in addition to a more precise finish.

^１ ｎ．ｄ．＝測定せず

¹ n. d. = Not measured

Examples 4 to 6 and Comparative Examples M to R
A phenolic resin-bonded integrated grinding wheel was made using the components listed in Table 3 according to the procedure described above in the section on agglomeration and integrated grinding wheel preparation. This integrated grinding wheel was tested according to the integrated grinding wheel performance test and the finishing test of the integrated grinding wheel. The results are shown in Table 4.

  The results show that the trend of the finished data (for non-agglomerated / urethane agglomerates / phenolic resin agglomerates) also applies to non-flexible grinding wheels bonded with a second binder of phenolic resin. Urethane agglomerates provide a finer finish than controls, and phenolic resin agglomerates provide a rougher finish.

Examples 7a, 7b and 7c and Comparative Examples S to Y
The AR1 modulus was measured according to the procedure in the section on measuring resin modulus. Grinding wheels with urethane bonds, containing agglomerates bound by various free radical curable resins, according to the procedure described above in the section on agglomeration and monolithic grinding wheel construction according to Table 5 Prepared using components. The integrated grinding wheel was tested according to the finishing test of the integrated grinding wheel. The results are shown in Table 6.

  The results show that a transition occurs when the elastic modulus value falls below 30,000 psi (206.84 MPa) as measured by ASTM D882 for the purpose of defining the agglomerated binder resin as “flexible” or “rigid”. Shows that the data demonstrates.

^１ 樹脂供給元によって提供された値、ＡＳＴＭ Ｄ８８２を用いて決定。

¹ Value provided by resin supplier, determined using ASTM D882.

Examples 8 and 9, and Examples Z and AA
Examples 8 and 9 and Examples Z and AA were made to demonstrate the effect of the filler on the finish produced by the correctly shaped particle agglomerates. An integral grinding wheel bonded with urethane was made using the components listed in Table 7 according to the procedure described above in the section on the formation of agglomerates and the fabrication of the integral grinding wheel. This integrated grinding wheel was tested according to the integrated grinding wheel performance test and the finishing test of the integrated grinding wheel. Table 8 shows the results.

  The results show that a more precise finish can be obtained by adding fillers (particles other than the formed ceramic abrasive particles) to the flexible binder agglomerates of the formed ceramic abrasive particles.

Examples 10 and 11
Examples 10 and 11 were made to demonstrate that unexpected and improved finishing results are independent of the agglomerate formation method. An integral grinding wheel bonded with urethane was made using the variables listed in Table 9 according to the procedure described above in the section on the formation of agglomerates and the fabrication of the integral grinding wheel. This integrated grinding wheel was tested according to the integrated grinding wheel performance test and the finishing test of the integrated grinding wheel. The results are shown in Table 10.

  The results show that the surprising finish improvement brought about by agglomerating shaped ceramic abrasive particles with a flexible resin is independent of the agglomerate shape. Examples 1 to 7 and Comparative Examples A to Y were formed into squares. Examples 10 and 11 were irregularly shaped.

  Those skilled in the art may make other modifications and changes to the present disclosure without departing from the spirit and scope of the present disclosure more specifically set forth in the appended claims. It should be understood that aspects of the various embodiments may be interchanged or combined in part or in whole with other aspects of the various embodiments. References, patents, or patent applications cited in the above-mentioned applications are hereby incorporated by reference in their entirety in a consistent manner. In the event of a partial discrepancy or inconsistency between these incorporated references and this specification, the information in the preceding description will prevail. The previous description provided to enable one skilled in the art to practice the disclosure of the claims shall be construed as limiting the scope of the disclosure as defined by the claims and all equivalents thereto. Should not.

Claims (4)

A non-woven fiber web;
An agglomerate comprising formed ceramic abrasive particles bonded by a first flexible binder;
A second binder which binds the aggregates to the nonwoven fibrous web, only including,
A nonwoven fabric abrasive article , wherein a ratio of the size of the formed ceramic abrasive particles divided by the size of the agglomerates is 0.0033 to 0.5 .   The nonwoven abrasive article of claim 1, wherein the formed ceramic abrasive particles comprise formed ceramic abrasive particles comprising a triangular plate.   The nonwoven fabric abrasive article according to claim 1 or 2, wherein the elastic modulus of the first flexible binder is less than 28,000 psi (193.05 MPa). The agglomerates contain filler particles;
The content of the formed ceramic abrasive particles is 75 wt% to 96 wt%,
The content of the first flexible binder is 4 wt% to 10 wt%,
The nonwoven fabric abrasive | polishing article of Claim 1 or 2 whose content of the said filler particle is 10 weight%-35 weight%.

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