Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
  • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
  • B24D3/28—Resins or natural or synthetic macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
  • B24D11/001—Manufacture of flexible abrasive materials
  • B24D11/005—Making abrasive webs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
  • B24D18/0072—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for using adhesives for bonding abrasive particles or grinding elements to a support, e.g. by gluing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
  • B24D3/342—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent
  • B24D3/344—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent the bonding agent being organic

Definitions

• the present disclosure relates to abrasive articles including a phenolic binder material and abrasive particles, and methods of making the same.
• Abrasive articles generally comprise abrasive particles (also known as "grains") retained within a binder.
• abrasive particles also known as "grains”
• the abrasive particles are deposited on a binder material precursor in an oriented manner (e.g., by electrostatic coating or by some mechanical placement technique).
• the most desirable orientation of the abrasive particles is substantially perpendicular to the surface of the backing.
• the backing is a relatively dense planar substrate (e.g., vulcanized fiber or a woven or knit fabric, optionally treated with a saturant to increase durability).
• a make layer precursor (or make coat) containing a first binder material precursor is applied to the backing, and then the abrasive particles are partially embedded into the make layer precursor.
• the abrasive particles are embedded in the make layer precursor with a degree of orientation; e.g., by electrostatic coating or by a mechanical placement technique.
• the make layer precursor is then at least partially cured in order to retain the abrasive particles when a size layer precursor (or size coat) containing a second binder material precursor is overlaid on the at least partially cured make layer precursor and abrasive particles.
• a size layer precursor or size coat
• the size layer precursor, and the make layer precursor if not sufficiently cured, are cured to form the coated abrasive article.
• a supersize layer overlays the size layer.
• the coated abrasive product is often manufactured as a continuous web that is dried and cured in festoon ovens, where the web is draped over hanger bars that progress through the oven.
• Flow of the size layer precursor and/or supersize layer due to gravity can be a problem during curing in a festoon oven, especially if the abrasive particles are aligned such that flow is not impeded by the abrasive particles.
• the recent trend toward precise placement and/or orientation of the abrasive particles has increased the need for a solution to the gravity flow problem discussed above.
• the present disclosure overcomes this problem by using a resole phenolic-based curable composition (typically thixotropic) suitable for use in manufacture of an abrasive article.
• the curable composition comprises a liquid phenolic resin and an organic polymeric rheology modifier comprising an alkali-swellable/soluble polymer.
• organic polymeric rheology modifiers are presently discovered to provide better control of size layer precursor flow than the techniques previously used.
• Organic polymeric rheology modifiers are known to give pseudoplastic flow characteristics.
• Alkali-Swellable/soluble Emulsion (ASE) polymers have been used in aqueous compositions for latex paints, personal care products, and drilling muds.
• Alkali-Swellable/soluble Emulsion (ASE) polymers expressly excludes Hydrophobically-modified Alkali-Swellable/soluble Emulsion (HASE) polymers.
• the present disclosure provides a method of making a coated abrasive article comprising: providing a backing having first and second opposed major surfaces, wherein a make layer is disposed on at least a portion of the first major surface and bonds abrasive particles to the backing; coating a size layer precursor over at least a portion of the make layer and the abrasive particles, wherein the size layer precursor comprises a resole phenolic resin and an organic polymeric rheology modifier, wherein the organic polymeric rheology modifier comprises an alkali-swellable/soluble polymer, and, on a solids basis, and wherein the amount of the resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the resole phenolic resin and the organic polymeric rheology modifier, and at least partially curing the size layer precursor to provide a size layer, and optionally coating an optional supersize layer precursor over at least a portion of the size layer and at least partially curing the optional supersize layer precursor to provide an
• the present disclosure provides a coated abrasive article comprising: a backing having first and second opposed major surfaces, a make layer disposed on at least a portion of the first major surface and bonding abrasive particles to the backing; a size layer overlaid on at least a portion of the make layer and the abrasive particles; and an optional supersize layer, wherein at least one of the size layer or the optional supersize layer comprises an at least partially cured resole phenolic resin and an organic polymeric rheology modifier, and wherein the amount of the at least partially cured resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the at least partially cured resole phenolic resin and the organic polymeric rheology modifier.
• alkali-swellable means at least partially swellable in an aqueous solution of a water-soluble base having a pH of greater than 7;
• alkali-swellable/soluble means at least one of alkali-swellable or alkali-soluble (i.e., alkali- swellable and/or alkali-soluble);
• polymer refers to an organic polymer unless otherwise clearly indicated.
• FIG. 1 is a schematic cross-sectional side view of an exemplary coated abrasive article 100 according to the present disclosure.
• FIG. 2 is a schematic perspective view of exemplary precisely-shaped abrasive particle 200.
• coated abrasive article 100 has backing 120 and abrasive layer 130.
• Abrasive layer 130 includes abrasive particles 140 secured to major surface 170 of backing 120 by make layer 150 and size layer 160.
• Optional supersize layer 180 overlays size layer 160.
• Coated abrasive articles according to the present disclosure may include additional layers such as, for example, a backing antistatic treatment layer and/or an attachment layer may also be included, if desired.
• Useful backings include, for example, those known in the art for making coated abrasive articles.
• the backing has two opposed major surfaces, although this is not a requirement.
• the thickness of the backing generally ranges from about 0.02 to about 5 millimeters, desirably from about 0.05 to about 2.5 millimeters, and more desirably from about 0.1 to about 1.0 millimeter, although thicknesses outside of these ranges may also be useful.
• the strength of the backing should be sufficient to resist tearing or other damage during abrading processes.
• the thickness and smoothness of the backing should also be suitable to provide the desired thickness and smoothness of the coated abrasive article; for example, depending on the intended application or use of the coated abrasive article.
• Exemplary backings include dense nonwoven fabrics (e.g., needletacked, meltspun, spunbonded, hydroentangled, or meltblown nonwoven fabrics), knitted fabrics, stitchbonded and/or woven fabrics; scrims; polymer films; treated versions thereof; and combinations of two or more of these materials.
• Fabric backings can be made from any known fibers, whether natural, synthetic or a blend of natural and synthetic fibers.
• useful fiber materials include fibers or yams comprising polyester (e.g., polyethylene terephthalate), polyamide (e.g., hexamethylene adipamide, polycaprolactam), polypropylene, acrylic, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymers, vinyl chloride-acrylonitrile copolymers, graphite, polyimide, silk, cotton, linen, jute, hemp, or rayon.
• Useful fibers may be of virgin materials or of recycled or waste materials reclaimed from garment cuttings, carpet manufacturing, fiber manufacturing, or textile processing, for example.
• Useful fibers may be homogenous or a composite such as a bicomponent fiber (for example, a co-spun sheath-core fiber).
• the fibers may be tensilized and crimped, but may also be continuous filaments such as those formed by an extrusion process.
• the backing may have any suitable basis weight; typically, in a range of from 100 to 1250 grams per square meter (gsm), mote typically 450 to 600 gsm, and even more typically 450 to 575 gsm.
• the backing typically has good flexibility; however, this is not a requirement (e.g., vulcanized fiber discs).
• one or more surfaces of the backing may be modified by known methods including corona discharge, ultraviolet light exposure, electron beam exposure, flame discharge, and/or scuffing.
• the make layer is formed by at least partially curing a make layer precursor comprising a thermosetting/curable compositioa
• suitable thermosetting/curable resins include, for example, free-radically polymerizable monomers and/or oligomers, epoxy resins, acrylic resins, urethane resins, phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, aminoplast resins, cyanate resins, and combinations thereof.
• Useful binder precursors include thermally curable resins and radiation curable resins, which may be cured, for example, thermally and/or by exposure to radiation. Additional details concerning make layer precursors may be found in U.S. Pat.
• the make layer precursor and the make layer may be modified by various additives (e.g., fibers, lubricants, wetting agents, surfactants, pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide, and/or graphite.), coupling agents (e.g., silanes, titanates, zircoaluminates, etc.), plasticizers, suspending agents).
• the make layer precursor comprises a resole phenolic resin and an organic polymeric rheology modifier of a type suitable for use in a size layer and/or supersize layer precursor, and which may aid in preserving the initial placement and orientation of the abrasive particles during manufacture.
• At least one of the size layer precursor and/or the optional supersize layer precursor comprises a resole phenolic resin and an organic polymeric rheology modifier.
• the organic polymeric rheology modifier comprises an alkali-swellable/soluble polymer.
• the amount of the resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the resole phenolic resin and the organic polymeric rheology modifier.
• the size layer precursor may comprise a different thermosetting/curable compositioa
• suitable thermosetting/curable resins include, for example, free- radically polymerizable monomers and/or oligomers, epoxy resins, acrylic resins, urethane resins, phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, aminoplast resins, cyanate resins, and combinations thereof.
• binder precursors include thermally curable resins and radiation curable resins, which may be cured, for example, thermally and/or by exposure to radiation. Additional details concerning size layer precursors may be found in U.S. Pat. No. 4,588,419 (Caul et al.), U.S. Pat. No. 4,751,138 (Tumey et al.), and U.S. Pat. No. 5,436,063 (Follett et al.).
• the size layer precursor may also be modified by various additives such as, for example, fibers, lubricants, wetting agents, surfactants, pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide, and/or graphite), coupling agents (e.g., silanes, titanates, zircoaluminates, etc.), plasticizers, and/or suspending agents.
• additives such as, for example, fibers, lubricants, wetting agents, surfactants, pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide, and/or graphite), coupling agents (e.g., silanes, titanates, zircoaluminates, etc.), plasticizers, and/or suspending agents.
• the supersize layer precursor comprises resole phenolic resin and an organic polymeric rheology modifier
• a supersize layer it may comprise components as described for the size layer precursor, or components known in the art for use as a supersize layer, for example.
• useful supersize layer precursor compositions include metal salts of fatty acids, urea-formaldehyde, novolac phenolic resins, epoxy resins, waxes, mineral oils, and combinations thereof.
• the supersize layer typically has a basis weight of 5 to 1100 grams per square meter (gsm), preferably 50 to 700 gsm, and more preferably 250 to 600 gsm, although this is not a requirement.
• the basis weight of the make layer, size layer, and optional supersize layer typically depend at least in part on the abrasive particle size grade and the particular type of abrasive article.
• Phenolic resins are generally formed by condensation of phenol and formaldehyde, and are usually categorized as resole or novolac phenolic resins. Novolac phenolic resins are acid-catalyzed and have a molar ratio of formaldehyde to phenol of less than 1:1. Resole (also resol) phenolic resins can be catalyzed by alkaline catalysts, and the molar ratio of formaldehyde to phenol is greater than or equal to one, typically between 1.0 and 3.0, thus presenting pendant methylol groups.
• Alkaline catalysts suitable for catalyzing the reaction between aldehyde and phenolic components of resole phenolic resins include sodium hydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide, organic amines, and sodium carbonate, all as solutions of the catalyst dissolved in water.
• Resole phenolic resins are typically coated as a solution with water and/or organic solvent (e.g., alcohol). Typically, the solution includes about 70 percent to about 85 percent solids by weight, although other concentrations may be used. If the solids content is very low, then more energy is required to remove the water and/or solvent. If the solids content is very high, then the viscosity of the resulting phenolic resin is too high which typically leads to processing problems.
• water and/or organic solvent e.g., alcohol
• Phenolic resins are well-known and readily available from commercial sources.
• Examples of commercially available resole phenolic resins useful in practice of the present disclosure include those marketed by Durez Corporation under the trade designation VARCUM (e.g., 29217, 29306, 29318, 29338, 29353); those marketed by Ashland Chemical Co. of Bartow, Florida under the trade designation AEROFENE (e.g., AEROFENE 295); and those marketed by Kangnam Chemical Company Ltd. of Seoul, South Korea under the trade designation PHENOLITE (e.g., PHENOLITE TD-2207).
• VARCUM e.g., 29217, 29306, 29318, 29338, 29353
• AEROFENE e.g., AEROFENE 295
• PHENOLITE e.g., PHENOLITE TD-2207
• the curable composition contains an organic polymeric rheology modifier that comprises an alkali-swellable/soluble polymer.
• the curable composition comprises a resole phenolic resin (typically diluted with water) and an organic polymeric rheology modifier that comprises an alkali-swellable/soluble polymer.
• the amount of the resole phenolic resin comprises from 75 to 99.99 weight percent (preferably 82 to 99.99 weight percent, and even more preferably 88 to 99.99 weight percent) of the combined weight of the resole phenolic resin and the organic polymeric rheology modifier.
• the curable composition contains from 0.01 to 25 weight percent, preferably 0.01 to 18 weight percent, and more preferably 0.01 to 12 weight percent of the organic polymeric rheology modifier, based on the combined weight of the resole phenolic resin and the organic polymeric rheology modifier. Combinations of more than one resole phenolic resin and/or more than one organic polymeric rheology modifier may be used if desired.
• Alkali-swellable/soluble polymers suitable for use as the organic polymeric rheology modifier include, for example, Alkali-Swellable/soluble Emulsion (ASE) organic polymers, Hydrophobically- modified Alkali-Swellable/soluble Emulsion polymers (HASE), and Hydrophobically modified Ethoxy lated URethane polymers (HEUR).
• ASE Alkali-Swellable/soluble Emulsion
• HASE Hydrophobically- modified Alkali-Swellable/soluble Emulsion polymers
• HEUR Hydrophobically modified Ethoxy lated URethane polymers
• the organic polymeric rheology modifier may be chosen from alkali-swellable/soluble acrylic emulsion polymers (ASE), Hydrophobically-modified alkali-swellable/soluble acrylic emulsion polymers (HASE), and Bydrophobically-modified Ethoxy lated URethane (HEUR) organic polymers, for example.
• ASE alkali-swellable/soluble acrylic emulsion polymers
• HASE Hydrophobically-modified alkali-swellable/soluble acrylic emulsion polymers
• HEUR Bydrophobically-modified Ethoxy lated URethane
• Alkali-Swellable/soluble Emulsion (ASE) rheology modifiers are dispersions of insoluble aciylic polymers in water have a high percentage of acid groups distributed throughout their polymer chains.
• the salt that is formed is hydrated.
• the salt either swells in aqueous solutions or becomes completely water-soluble.
• ASE polymers can be synthesized from acid and acrylate co-monomers, and are generally made through emulsion polymerization
• Exemplary commercially available ASE polymers include ACUSOL 810A, ACUSOL 830, ACUSOL 835, and ACUSOL 842 polymers.
• HASE polymers are commonly employed to modify the rheological properties of aqueous emulsion systems. Under the influence of a base, organic or inorganic, the HASE particles gradually swell and expand to form a three-dimensional network by intermolecular hydrophobic aggregation between HASE polymer chains and/or with components of the emulsion. This network, combined with the hydrodynamic exclusion volume created by the expanded HASE chains, produces the desired thickening effect. This network is sensitive to applied stress, breaks down under shear and recovers when the stress is relieved.
• HASE rheology modifiers can be prepared from the following monomers: (a) an ethylenically unsaturated carboxylic acid (b) a nonionic ethylenically unsaturated monomer, and (c) an ethylenically unsaturated hydrophobic monomer.
• Representative HASE polymer systems include those shown in EP 226097 B1 (van Phung et al.), EP 705852 B1 (Doolan et al.), U.S. Pat. No. 4,384,096 (Sonnabend) and U.S. Pat No. 5,874,495 (Robinson).
• Exemplary commercially available HASE polymers include those marketed by Dow Chemical under the trade designations ACUSOL 801S, ACUSOL 805S, ACUSOL 820, and ACUSOL 823.
• ASE and HASE theology modifiers are pB-triggered thickeners. Whether the emulsion polymer in each is water-swellable or water-soluble typically depends on its molecular weight. Both forms are acceptable. Further details concerning synthesis of ASE and HASE polymers can be found for example, in U.S. Pat. No. 9,631,165 (Droege et al.).
• HEUR Ethoxy lated URethane
• HEURs are water-soluble polymers containing hydrophobic groups, and are classified as associative thickeners because the hydrophobic groups associate with one another in water.
• HEURs are nonionic substances and are not dependent on alkali for activation of the thickening mechanism. They develop intra- or intermolecular links as their hydrophobic groups associate with other hydrophobic ingredients in a given formulation. As a general rule, the strength of the association depends on the number, size, and frequency of the hydrophobic capping or blocking units.
• HEURs develop micelles as would a normal surfactant The micelles then link between the other ingredients by associating with their surfaces. This builds a three- dimensional network.
• HEUR polymers include those marketed by Dow Chemical under the trade designations ACUSOL 880, ACUSOL 882, ACRYSOL RM-2020, and ACRYSOL RM-
• HEURs HEURs
• Appl. Publ. No. 2017/0198238 Ken founded et al.
• 2017/0130072 McCulloch et al.
• U.S. Pat. Nos. 7,741,402 Bobsein et al.
• 8,779,055 Rasco et al.
• the make layer, size layer, and optional supersize layer are formed by at least partially curing corresponding precursors (i.e., a make layer precursor, a size layer precursor, a supersize layer precursor).
• the make layer, size layer, and optional supersize layer and their precursors may also contain additives such as fibers, lubricants, wetting agents, surfactants, pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide, and/or graphite), coupling agents (e.g., silanes, titanates, and/or zircoaluminates), plasticizers, suspending agents, and the like.
• additives such as fibers, lubricants, wetting agents, surfactants, pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide, and/or graphite), coupling agents (e.g., silanes, titanates, and/or zircoaluminates), plasticizers, suspending agents, and the like.
• the amounts of these optional additives are selected to provide the preferred properties.
• the coupling agents can improve adhesion to the abrasive particles and/or filler.
• the curable composition may be thermally-cured radiation-cured
• the make layer, size layer, and optional supersize layer and their precursors may also contain filler materials, diluent abrasive particles (e.g., as described hereinbelow), or grinding aids, typically in the form of a particulate material.
• the particulate materials are inorganic materials.
• metal carbonates e.g., calcium carbonate (e.g., chalk, calcite, marl, travertine, marble and limestone), calcium magnesium carbonate, sodium carbonate, magnesium carbonate
• silica e.g., quartz, glass beads, glass bubbles and glass fibers
• silicates e.g., talc, clays, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate
• metal sulfates e.g., calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate), gypsum, vermiculite, wood flour, aluminum trihydrate, carbon black, metal oxides (e.g., calcium oxide (lime), aluminum oxide, titanium dioxide), and metal sulfites (e.g., calcium sulfite).
• Heat energy is commonly applied to advance curing of the thermosetting/curable resins used in the make layer precursor/size layer precursor, and optionally in the supersize layer precursor; however, other sources of energy (e.g., microwave radiation, infrared light, ultraviolet light, visible light, may also be used).
• sources of energy e.g., microwave radiation, infrared light, ultraviolet light, visible light, may also be used.
• the selection will generally be dictated by the particular resin system selected.
• Useful abrasive particles may be the result of a crushing operation (e.g., crushed abrasive particles that have been sorted for shape and size) or the result of a shaping operation (i.e., shaped abrasive particles) in which an abrasive precursor material is shaped (e.g., molded), dried, and converted to ceramic material. Combinations of abrasive particles resulting from crushing with abrasive particles resulting from a shaping operation may also be used.
• the abrasive particles may be in the form of, for example, individual particles, agglomerates, composite particles, and mixtures thereof.
• the abrasive particles should have sufficient hardness and surface roughness to function as crushed abrasive particles in abrading processes.
• the abrasive particles have a Mohs hardness of at least 4, at least 5, at least 6, at least 7, or even at least 8.
• Suitable abrasive particles include, for example, crushed abrasive particles comprising fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M Company, St.
• sol-gel-derived ceramic e.g., alpha alumina
• abrasive particles could comprise abrasive agglomerates such, for example, as those described in U.S. Pat. Nos. 4,652,275 (Bloecher et al.) or 4,799,939 (Bloecher et al.).
• 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 crushed abrasive particles to the binder.
• a coupling agent e.g., an organosilane coupling agent
• other physical treatment e.g., iron oxide or titanium oxide
• the abrasive particles may be treated before combining them with the binder, or they may be surface treated in situ by including a coupling agent to the binder.
• the abrasive particles (and especially the abrasive particles) comprise ceramic abrasive particles such as, for example, sol-gel-derived poly crystalline alpha alumina particles.
• Ceramic abrasive particles composed of crystallites of alpha alumina, magnesium alumina spinel, and a rare earth hexagonal aluminate may be prepared using sol-gel precursor alpha alumina particles according to methods described in, for example, U.S. Pat. No. 5,213,591 (Celikkaya et al.) and U.S. Publ. Pat. Appln. Nos. 2009/0165394 A1 (Culler et al.) and 2009/0169816 Al (Erickson et al.).
• useful abrasive particles may be shaped abrasive particles can be found in U.S. Pat. Nos. 5,201,916 (Berg); 5,366,523 (Rowenhorst (Re 35,570)); and 5,984,988 (Berg).
• U.S. Pat. No. 8,034,137 (Erickson et al.) describes alumina abrasive particles that have been formed in a specific shape, then crushed to form shards that retain a portion of their original shape features.
• the abrasive particles are precisely-shaped (i.e., the particles have shapes that are at least partially determined by the shapes of cavities in a production tool used to make them. Details concerning such abrasive particles and methods for their preparation can be found, for example, in U.S. Pat Nos. 8,142,531 (Adefris et al.); 8,142,891 (Culler et al.); 8,142,532 (Erickson et al.); 9,771,504 (Adefris); and in U.S. Pat. Appl. Publ. Nos.
• One particularly useful precisely-shaped abrasive particle shape is that of a platelet having three-sidewalls, any of which may be straight or concave, and which may be vertical or sloping with respect to the platelet base; for example, as set forth in the above cited references.
• An exemplary such precisely-shaped abrasive particle 200 is shown in FIG. 2.
• Surface coatings on the abrasive particles may be used to improve the adhesion between the abrasive particles and a binder material, or to aid in electrostatic deposition of the abrasive particles.
• surface coatings as described in U.S. Pat. No. 5,352,254 (Celikkaya) in an amount of 0.1 to 2 percent surface coating to abrasive particle weight may be used. Such surface coatings are described in U.S. Pat Nos.
• the surface coating may prevent shaped abrasive particles from capping.
• Capping is the term to describe the phenomenon where metal particles from the workpiece being abraded become welded to the tops of the abrasive particles.
• the abrasive particles may be selected to have a length and/or width in a range of from 0.1 micrometers to 3.5 millimeters (mm), mote 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.
• the abrasive particles may be selected to have a thickness in a range of from 0.1 micrometer to 1.6 mm, more typically from 1 micrometer to 1.2 mm, although other thicknesses may be used.
• abrasive particles may have an aspect ratio (length to thickness) of at least 2, 3, 4, 5, 6, or more.
• Abrasive particles may be independently sized according to an abrasives industry recognized specified nominal grade.
• Exemplary abrasive industry recognized grading standards include those promulgated by ANSI (American National Standards Institute), FEPA (Federation of European Producers of Abrasives), and JIS (Japanese Industrial Standard).
• Such industry accepted grading standards include, for example: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 30, 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; FEPA P8, FEPA P12, FEPA P16, FEPA P24, FEPA P30, FEPA P36, FEPA P40, FEPA P50, FEPA P60, FEPA P80, FEPA P100, FEPA P120, FEPA P150, FEPA P180, FEPA P220, FEPA P320, FEPA P400, FEPA P500, FEPA P600, FEPA P800, FEPA P1000, FEPA P1200; FEPA F8, FEPA F12, FEPA F16, and FEPA F24;.and
• the crushed aluminum oxide particles and the non-seeded sol-gel derived alumina-based abrasive particles are independently sized to ANSI 60 and 80, or FEPA F36, F46, F54 and F60 or FEPA P60 and P80 grading standards.
• the abrasive particles can be graded to a nominal screened grade using U.S. A. Standard Test Sieves conforming to ASTM E-11 "Standard Specification for Wire Cloth and Sieves for Testing Purposes".
• ASTM E-11 prescribes the requirements for the design and construction of testing sieves using a medium of woven wire cloth mounted in a frame for the classification of materials according to a designated particle size.
• a typical designation may be represented as -18+20 meaning that the shaped abrasive particles pass through a test sieve meeting ASTM E-11 specification for the number 18 sieve and ate retained on a test sieve meeting ASTM E-11 specification for the number 20 sieve.
• the shaped abrasive particles have a particle size such that most of the particles pass through an 18 mesh test sieve and can be retained on a 20, 25, 30, 35, 40, 45, or 50 mesh lest sieve.
• the shaped abrasive particles can have a nominal screened grade comprising: -18+20, -20+25, -25+30, -30+35, -35+40, -40+45, -45+50, -50+60, -60+70, -70+80,
• a custom mesh size could be used such as -90+100.
• a grinding aid is a material that has a significant effect on the chemical and physical processes of abrading, which results in improved performance.
• Grinding aids encompass a wide variety of different materials and can be inorganic or organic based. Examples of chemical groups of grinding aids include waxes, organic halide compounds, halide salts and metals and their alloys. The organic halide compounds will typically break down during abrading and release a halogen acid or a gaseous halide compound. Examples of such materials include chlorinated waxes like tetrachloronaphthalene, penlachloronaphthalene, and polyvinyl chloride.
• halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride.
• metals include, tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium
• miscellaneous grinding aids include sulfur, organic sulfur compounds, graphite, and metallic sulfides. A combination of different grinding aids may be used, and in some instances, this may produce a synergistic effect
• Grinding aids can be particularly useful in coated abrasives.
• grinding aid is typically used in a supersize layer, which is applied over the surface of the size layer. Sometimes, however, the grinding aid is added to the size layer.
• the amount of grinding aid incorporated into coated abrasive articles are about 50-800 grams per square meter (g/m 2 ), preferably about 80-475 g/m 2 , however, this is not a requirement.
• coated abrasive articles and methods of their manufacture can be found, for example, inU.S. Pat. Nos. 4,734,104 (Broberg); 4,737,163 (Larkey); 5,203,884 (Buchanan et al.); 5, 152,917 (Pieper et al.); 5,378,251 (Culler et al.); 5,436,063 (Follett et al.); 5,496,386 (Broberg et al.); 5,609,706 (Benedict et al.); 5, 520,711 (Helmin); 5,961,674 (Gagliardi et al.), and 5,975,988 (Christianson).
• Coated abrasive articles according to the present disclosure are useful, for example, for abrading a workpiece.
• Such a method may comprise frictionally contacting an abrasive article according to the present disclosure with a surface of the workpiece, and moving at least one of the coated abrasive article and the surface of the workpiece relative to the other to abrade at least a portion of the surface of the workpiece.
• Methods for abrading with coated abrasive articles according to the present disclosure include, for example, snagging (i.e., high-pressure high stock removal) to polishing (e.g., polishing medical implants with coated abrasive belts), wherein the latter is typically done with finer grades (e.g., ANSI 220 and finer) of abrasive particles.
• snagging i.e., high-pressure high stock removal
• polishing e.g., polishing medical implants with coated abrasive belts
• finer grades e.g., ANSI 220 and finer
• Abrading may be carried out dry or wet
• the liquid may be introduced supplied in the form of a light mist to complete flood.
• Examples of commonly used liquids include water, water- soluble oil, organic lubricant and emulsions.
• the liquid may serve to reduce the heat associated with abrading and/or act as a lubricant.
• the liquid may contain minor amounts of additives such as bactericide, antifoaming agents, and the like.
• workpieces include aluminum metal, carbon steels, mild steels (e.g., 1018 mild steel and 1045 mild steel), tool steels, stainless steel, hardened steel, titanium, glass, ceramics, wood, wood-like materials (e.g., plywood and particle board), paint, painted surfaces, and organic coated surfaces.
• the applied force during abrading typically ranges from about 1 to about 100 kilograms (kg), although other pressures can also be used.
• the present disclosure provides a method of making a coated abrasive article comprising: providing a backing having first and second opposed major surfaces, wherein a make layer is disposed on at least a portion of the first major surface and bonds abrasive particles to the backing; coating a size layer precursor over at least a portion of the make layer and the abrasive particles, wherein the size layer precursor comprises a resole phenolic resin and an organic polymeric rheology modifier, wherein the organic polymeric rheology modifier comprises an alkali-swellable/soluble polymer, and, on a solids basis, and wherein the amount of the resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the resole phenolic resin and the organic polymeric rheology modifier, and at least partially curing the size layer precursor to provide a size layer, and optionally coating an optional supersize layer precursor over at least a portion
• the present disclosure provides a method according to the first embodiment, wherein at least one of said at least partially curing the size layer precursor or said at least partially curing the supersize layer precursor occurs in a festoon oven.
• the present disclosure provides a method according to the first or second embodiment, wherein at least one of the size layer precursor or the optional supersize layer precursor has a basis weight of 5 to 1100 grams per square meter.
• the present disclosure provides a method according to any of the first to third embodiments, wherein the organic polymeric rheology modifier is selected from the group consisting of alkali-swellable/soluble acrylic polymers, hydrophobically-modified alkali-swellable/soluble acrylic polymers, hydrophobically-modified ethoxylated urethane polymers, and combinations thereof.
• the organic polymeric rheology modifier is selected from the group consisting of alkali-swellable/soluble acrylic polymers, hydrophobically-modified alkali-swellable/soluble acrylic polymers, hydrophobically-modified ethoxylated urethane polymers, and combinations thereof.
• the present disclosure provides a method according to any of the first to fourth embodiments, wherein, on a solids basis, the amount of the resole phenolic resin comprises from 85 to 99.99 weight percent of the combined weight of the resole phenolic resin and the organic polymeric rheology modifier.
• the present disclosure provides a method according to any of the first to fifth embodiments, w'hercin the abrasive particles comprise shaped abrasive particles. In a seventh embodiment, the present disclosure provides a method according to the sixth embodiment, wherein the shaped abrasive particles comprise precisely-shaped abrasive particles.
• the present disclosure provides a method according to the sixth embodiment, wherein the shaped abrasive particles comprise precisely-shaped three-sided platelets.
• the present disclosure provides a coated abrasive article comprising: a backing having first and second opposed major surfaces, a make layer disposed on at least a portion of the first major surface and bonding abrasive particles to the backing; a size layer overlaid on at least a portion of the make layer and the abrasive particles; and an optional supersize layer, wherein at least one of the size layer or the optional supersize layer comprises an at least partially cured resole phenolic resin and an organic polymeric rheology modifier, and wherein the amount of the at least partially cured resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the at least partially cured resole phenolic resin and the organic polymeric rheology modifier.
• the present disclosure provides a coated abrasive article according to the ninth embodiment, wherein the organic polymeric rheology modifier is selected from the group consisting of alkali-swellable/soluble acrylic polymers, hydrophobically-modified alkali-swellable/soluble acrylic polymers, hydrophobically-modified ethoxy lated urethane polymers, and combinations thereof.
• the organic polymeric rheology modifier is selected from the group consisting of alkali-swellable/soluble acrylic polymers, hydrophobically-modified alkali-swellable/soluble acrylic polymers, hydrophobically-modified ethoxy lated urethane polymers, and combinations thereof.
• the present disclosure provides a coated abrasive article according to the ninth or tenth embodiment, wherein the amount of the at least partially cured resole phenolic resin comprises from 85 to 99.99 weight percent of the combined weight of the at least partially cured resole phenolic resin and the organic polymeric rheology modifier.
• the present disclosure provides a coated abrasive article according to any of the ninth to eleventh embodiments, wherein the abrasive particles comprise shaped abrasive particles.
• the present disclosure provides a coated abrasive article according to the twelfth embodiment, wherein the shaped abrasive particles comprise precisely-shaped abrasive particles.
• the present disclosure provides a coated abrasive article according to the twelfth embodiment, wherein the shaped abrasive particles comprise precisely-shaped three-sided platelets.
• Examples and comparative examples were prepared by massing all components into 3-Liter or 70-mm diameter polypropylene straight-walled jars according to the amounts indicated in Tables 1-4. Jars or containers were mixed with an overhead stirrer. If the mixture was not used for testing immediately it was stored in a refrigerator at 10 °C until use.
• Inclined Plane Flow Test for Size and Supersize Layer Precursor Examples and Comparative Examples The incline flow rate test involved placing 0.1 gram drop of resin at specified temperature onto horizontal positioned glass slide and then quickly tilting glass slide on incline device set at 48.7° angle from horizontal for one minute. The distance the resin travels in one minute is measured in millimeters (mm). The smaller the distance the less likely size or supersize resin will have excessive flow and cause bottom loop puddling in the festoon curing ovens.
• the incline data for Size Resin examples and comparative examples are reported in Tables 10 and 11. Supersize Resin examples and comparative examples are shown in Table 12.
• the flow characteristics of the phenolic copolymer mixtures were characterized by continuous flow rheometry using a TA Instruments Discovery Hybrid Rheometer 3 (TA Instruments, New Castle, Delaware) equipped with a stainless steel concentric cylinder geometry utilizing a conical end rotor with a 28.01 mm diameter and 41.96mm height, cup with a 30.35 mm diameter, and a TA instruments DHR & AR-Series Smart Swap Concentric Cylinder Peltier jacket for temperature control. Samples approximately 24 milliliters in volume were loaded onto the geometry cup via polypropylene syringe and the rotor was brought to a gap height 5.919 mm.
• a make layer precursor was prepared charging a 17-liter pail with 7812 grams of PF, 6823 grams of FIL4 and 364 grams of water. The resin was mixed with an overhead stirrer for 30 minutes at room temperature.
• Coated abrasive examples and comparative examples were prepared by roll coating make resin (described above) onto a continuous 30.48 cm wide polyester backing (described in Example 12 of U.S. Pat. No. 6,843,815 Thurber et al.) at a coating weight of 210 grams per square meter (gsm) followed by electrostatically coating mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90°C for 90 minutes and at 102°C for 60 minutes. The resultant material was then roll coated with size resin Comparative Example CE-A at a size weight of 567 gsm. The material was final cured at 90°C for 60 minutes and al 102°C for 12 hours.
• Coated abrasive examples and comparative examples were prepared by roll coating make resin (described above) onto a continuous 30.48 cm wide polyester backing (described in Example 12 of U.S. Pat. No. 6,843,815 Thurber et al.) at a coating weight of 210 gsm followed by electrostatically coating mineral SAP1 at a weight of 605 gsm.
• the coated material was cured at 90°C for 90 minutes and at 102°C for 60 minutes.
• the resultant material was then roll coated with size resin Example EX-27 at a size weight of 567 gsm. The material was final cured at 90°C for 60 minutes and at 102°C for 12 hours.
• Example CE-M showed typical bottom loop puddling while Example EX-31 had no observed puddling.
• Coaled abrasive examples and comparative examples were prepared by roll coating make resin (described above) onto a continuous 30.48 cm wide polyester backing (described in Example 12 of U.S. Pat. No. 6,843,815 Thurber et al.) at a coating weight of 210 gsm followed by electrostatically coating mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90°C for 90 minutes and at 102°C for 60 minutes. The resultant material was then roll coated with size resin Comparative Example CE-A at a size weight of 567 gsm. The material was cured at 90°C for 1 hour and at 102°C for 1 hour.
• Coaled abrasive examples and comparative examples were prepared by roll coating make resin (described above) onto a continuous 30.48 cm wide polyester backing (described in Example 12 of U.S. Pat. No. 6,843,815 Thurber et al.) at a coating weight of 210 gsm followed by electrostatically coating mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90°C for 90 minutes and at 102°C for 60 minutes. The resultant material was then roll coated with size resin Comparative Example CE-A at a size weight of 567 gsm. The material was cured at 90°C for 1 hour and at 102°C for 1 hour.
• Example EX-29 was then coated with supersize resin Example EX-29 at coating weight of 462 gsm using a 30.48 cm paint roller.
• the coated abrasive was final cured at 90°C for 60 minutes and at 102°C for 12 hours.

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• 2021
  • 2021-02-01 WO PCT/IB2021/050793 patent/WO2021161129A1/en unknown
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