Coated abrasive article and method of making same

Abstract

A coated abrasive article includes a backing having opposite first and second 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 covering at least a portion of the make layer and the abrasive particles; and a top size layer disposed on the size layer. The top size layer comprises an at least partially cured water-based epoxy resin and an organic polymeric rheology modifier, and wherein the amount of the at least partially cured epoxy resin is from 75 wt% to 99.99 wt% of the total weight of the at least partially cured epoxy resin and the organic polymeric rheology modifier. Also disclosed is a method of making a coated abrasive article.

Description

Technical Field

[0001] This disclosure relates to abrasive articles comprising epoxy top adhesive materials and methods for preparing the same. Background Technology

[0002] Abrasive articles typically contain abrasive particles (also known as “abrasive grains”) retained in a binder. During the manufacture of various types of abrasive articles, the abrasive particles are deposited onto a binder material precursor in an oriented manner (e.g., by electrostatic coating or by some mechanical placement technique). Typically, the most desired orientation of the abrasive particles is substantially perpendicular to the surface of the backing.

[0003] For certain coated abrasive articles (e.g., grinding discs), the backing is a relatively dense planar substrate (e.g., vulcanized fiber or woven or knitted fabric, optionally treated with an impregnating agent to increase durability). A primer precursor (or primer layer) containing a first binder material precursor is applied to the backing, and then abrasive particles are partially embedded in the primer precursor. In many cases, the abrasive particles are embedded in the primer precursor with a degree of orientation; for example, by electrostatic coating or by mechanical placement techniques. Then, when a re-adhesive precursor (or re-adhesive layer) containing a second binder material precursor is applied to the at least partially cured primer precursor and abrasive particles, the primer precursor is at least partially cured to retain the abrasive particles. Subsequently, if the re-adhesive precursor and the primer precursor are not sufficiently cured, both are cured to form a coated abrasive article.

[0004] In some cases, the topcoat layer can be formed from a corresponding topcoat layer precursor (adhesive layer).

[0005] For thermosetting topcoat precursors, coated abrasive products are typically manufactured as continuous webs that are dried and cured in a hanging oven, with the webs covering a hanging rod that moves forward through the oven. Summary of the Invention

[0006] During curing in a suspended oven, flow of the top adhesive layer due to gravity can be problematic, especially when the abrasive particles are arranged so that the flow is not obstructed by the particles. However, recent trends toward precise placement and / or orientation of abrasive particles have increased the need for solutions to the aforementioned gravity flow problem.

[0007] This disclosure overcomes these problems by using a topcoat precursor containing a water-based curable epoxy resin and a rheology modifier suitable for manufacturing abrasive articles. The rheology modifier includes an organic polymer rheology modifier comprising an alkali-swellable / soluble polymer. It has been found that these organic polymer rheology modifiers provide better control over the flow of the topcoat precursor compared to previously used techniques.

[0008] Organic polymer rheology modifiers are known to impart pseudoplastic flow properties. In particular, alkali-swellable / soluble emulsion (ASE) polymers, hydrophobically modified alkali-swellable / soluble emulsion (HASE) polymers, and hydrophobically modified ethoxylated polyurethane (HEUR) polymers have been used in aqueous compositions of latex paints, personal care products, and drilling muds. As used herein, the term "alkali-swellable / soluble emulsion (ASE) polymer" explicitly excludes hydrophobically modified alkali-swellable / soluble emulsion (HASE) polymers.

[0009] In a first aspect, this disclosure provides a method for preparing coated abrasive articles, the method comprising:

[0010] A backing having opposite first and second main surfaces is provided, wherein an adhesive base layer is disposed on at least a portion of the first main surface and abrasive particles are bonded to the backing, and further wherein an adhesive overlay is disposed on the adhesive base layer and at least a portion of the abrasive particles;

[0011] as well as

[0012] A topcoat layer precursor is coated onto at least a portion of the adhesive layer, and the topcoat layer precursor is at least partially cured to provide the topcoat layer.

[0013] The topcoat precursor contains a water-based epoxy resin and an organic polymer rheology modifier.

[0014] The organic polymer rheology modifier comprises an alkali-swellable / soluble polymer, and wherein, based on solids, the amount of the water-based epoxy resin accounts for 75% to 99.99% by weight of the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

[0015] In a second aspect, this disclosure provides a coated abrasive article comprising:

[0016] A backing having opposite first and second main surfaces;

[0017] An adhesive base layer is disposed on at least a portion of the first main surface and bonds abrasive particles to the backing.

[0018] A backing layer, which covers at least a portion of the base adhesive layer and the abrasive particles; and

[0019] Top adhesive layer, which is disposed on the top adhesive layer.

[0020] The topcoat layer comprises at least partially cured epoxy resin and an organic polymer rheology modifier, wherein the amount of the at least partially cured epoxy resin is from 75% to 99.99% by weight of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

[0021] As used in this article:

[0022] "Alkali swelling property" means that the plant can at least partially swell in an aqueous solution of a water-soluble alkali with a pH greater than 7.

[0023] "Alkali swelling / solubility" means at least one of alkali swelling or alkali solubility (i.e., alkali swelling and / or alkali solubility);

[0024] Unless otherwise expressly stated, "polymer" refers to organic polymers; and

[0025] "Water-based" means dissolved or dispersed in a liquid medium in which water is the main component.

[0026] The features and advantages of this disclosure will be further understood upon consideration of the specific embodiments and the appended claims. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional side view of an exemplary coated abrasive article 100 according to the present disclosure.

[0028] Figure 2 This is a schematic perspective view of an exemplary, precisely shaped abrasive particle 200.

[0029] Figure 3 This is a digital photograph of a coated abrasive article prepared using the comparative topcoat precursor CSSR-F.

[0030] Figure 4 This is a digital photograph of a coated abrasive product prepared using the topcoat precursor ESSR-5.

[0031] It should be understood that those skilled in the art can devise many other modifications and embodiments that fall within the scope and spirit of the principles of this disclosure. The accompanying drawings may not be drawn to scale. Detailed Implementation

[0032] According to exemplary embodiments of the coated abrasive articles disclosed herein Figure 1 As shown in the image. See now. Figure 1 The coated abrasive article 100 has a backing 120 and an abrasive layer 130. The abrasive layer 130 contains abrasive particles 140 fixed to the main surface 170 of the backing 120 by a base layer 150 and a top layer 160. A top layer 180 covers the top layer 160.

[0033] For example, coated abrasive articles according to this disclosure may include additional layers such as an antistatic backing layer, and / or, if desired, an attachment layer.

[0034] For example, usable backings include those known in the art for preparing coated abrasive articles. Typically, the backing has two opposite main surfaces, but this is not mandatory. The thickness of the backing is typically in the range of about 0.02 mm to about 5 mm, advantageously in the range of about 0.05 mm to about 2.5 mm, and more advantageously in the range of about 0.1 mm to about 1.0 mm, but thicknesses outside these ranges may also be used. Generally, the strength of the backing should be sufficient to resist tearing or other damage during the grinding process. The thickness and smoothness of the backing should also be suitable for providing the desired thickness and smoothness of the coated abrasive article; for example, according to the intended application or use of the coated abrasive article.

[0035] Exemplary backings include: dense nonwoven fabrics (e.g., needle-punched, melt-spun, spunbond, hydroentangled, or melt-blown nonwoven fabrics), knitted fabrics, stitch-knitted fabrics, and / or woven fabrics; loose fabrics; polymer films; their treated forms; and combinations of two or more of these materials.

[0036] The fabric backing can be made from any known fiber, whether natural, synthetic, or a blend of natural and synthetic fibers. Examples of usable fiber materials include fibers or yarns comprising polyester (e.g., polyethylene terephthalate), polyamide (e.g., hexamethylene adipamide, polycaprolactam), polypropylene, acrylic acid, cellulose acetate, polyvinylidene chloride-vinyl chloride copolymer, vinyl chloride-acrylonitrile copolymer, graphite, polyimide, silk, cotton, linen, jute, hemp, or rayon. Usable fibers can be natural materials or recycled or waste materials, for example, recovered from garment cutting, carpet manufacturing, fiber manufacturing, or textile processing. Usable fibers can be homogeneous or composite materials such as bicomponent fibers (e.g., co-spun sheath-core fibers). These fibers can be stretched and crimped, but can also be continuous filaments, such as those formed by extrusion processes.

[0037] The backing can have any suitable basis weight; typically, it ranges from 100 g / m² to 1250 g / m², more typically from 450 g / m² to 600 g / m², and even more typically from 450 g / m² to 575 g / m². In many embodiments (e.g., grinding belts and grinding discs), the backing typically has good flexibility; however, this is not necessary (e.g., vulcanized fiber discs). To promote adhesion of the adhesive resin to the backing, one or more surfaces of the backing can be modified by known methods, including corona discharge, ultraviolet irradiation, electron beam irradiation, flame discharge, and / or texturing.

[0038] The primer layer is formed by applying a primer precursor to the main surface of the backing and at least partially curing the primer precursor. The primer precursor comprises a thermosetting / curable composition. Examples of suitable thermosetting / curable resins that can be used for primer precursors include, for example, free radical polymerizable monomers and / or oligomers, epoxy resins, acrylic resins, polyurethane resins, phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, amino plastic resins, cyanate ester resins, and combinations thereof. Available adhesive precursors include thermosetting resins and radiation-curable resins, which can be cured, for example, by heat and / or by exposure to radiation. Depending on the curable resin, the amount of catalysts and / or initiators (e.g., thermal initiators and / or photoinitiators) typically included is up to 10% by weight of the primer precursor. The selection of catalysts and / or initiators is within the capabilities of those skilled in the art. Additional details regarding the primer precursor can be found in U.S. Patent Nos. 4,588,419 (Caul et al.), 4,751,138 (Tumey et al.), and 5,436,063 (Follett et al.).

[0039] The primer precursor and primer layer can 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, zirconium aluminates, etc.), plasticizers, suspending agents).

[0040] In some embodiments, the primer precursor comprises a methyl phenolic resin and an organic polymer rheology modifier. The organic polymer rheology modifier comprises an alkali-swellable / soluble polymer. The amount of the methyl phenolic resin, on a solids basis, is from 75% to 99.99% by weight of the total weight of the methyl phenolic resin and the organic polymer rheology modifier.

[0041] The organic polymer rheology modifier comprises an alkali-swellable / soluble polymer. On a solids basis, the amount of methyl phenolic resin accounts for 75% to 99.99% by weight of the total weight of the methyl phenolic resin and the organic polymer rheology modifier.

[0042] Generally, phenolic resins are formed through the condensation of phenol and formaldehyde, and are usually classified as resole-type phenolic resins or phenolic varnish resins. Phenolic varnish resins are acid-catalyzed, and the molar ratio of formaldehyde to phenol is less than 1:1. Resole-type phenolic resins can be catalyzed by basic catalysts, and the molar ratio of formaldehyde to phenol is greater than or equal to one, typically between 1.0 and 3.0, thus exhibiting hydroxymethyl side groups. Suitable basic catalysts for catalyzing the reaction between the aldehyde and phenolic components of resole-type phenolic resins include sodium hydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide, organic amines, and sodium carbonate, all of which are catalyst solutions dissolved in water.

[0043] Acetylated phenolic resins are typically coated as solutions containing water and / or organic solvents (e.g., alcohols). Typically, the solution contains solids of about 70% to about 85% by weight, but other concentrations can be used. If the solids content is very low, more energy is required to remove the water and / or solvent. If the solids content is very high, the resulting phenolic resin has excessively high viscosity, which often leads to processing problems.

[0044] Phenolic resins are well known and readily available from commercial sources. Examples of commercially available methyl phenolic resins that can be used to implement this disclosure include those sold by Durez Corporation under the trade name VARCUM (e.g., 29217, 29306, 29318, 29338, 29353); those sold by Ashland Chemical Co., Bartow, Florida under the trade name AEROFENE (e.g., AEROFENE 295); and those sold by Kangnam Chemical Company Ltd. of Seoul, South Korea under the trade name PHENOLITE (e.g., PHENOLITE TD-2207).

[0045] A review discussion of phenolic resins and their manufacture is given in the following reference: Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., John Wiley & Sons, 1996, New York, Vol. 18, pp. 603-644.

[0046] In addition to the methyl phenolic resin, the curable composition contains an organic polymer rheology modifier comprising an alkali-swellable / soluble polymer. The curable composition comprises a methyl phenolic resin (typically diluted with water) and an organic polymer rheology modifier comprising an alkali-swellable / soluble polymer. On a solids basis, the amount of the methyl phenolic resin is 75% to 99.99% by weight (preferably 82% to 99.99% by weight, and even more preferably 88% to 99.99% by weight) of the total weight of the methyl phenolic resin and the organic polymer rheology modifier. Therefore, based on the total weight of the methyl phenolic resin and the organic polymer rheology modifier, the curable composition contains 0.01% to 25% by weight, preferably 0.01% to 18% by weight, and more preferably 0.01% to 12% by weight of the organic polymer rheology modifier. If necessary, a combination of more than one methyl phenolic resin and / or more than one organic polymer rheology modifier may be used.

[0047] Alkali-swellable / soluble polymers suitable as rheology modifiers for organic polymers include, for example, alkali-swellable / soluble emulsion (ASE) organic polymers, hydrophobically modified alkali-swellable / soluble emulsion polymers (HASE), and hydrophobically modified ethoxylated polyurethane polymers (HEUR).

[0048] For example, the organic polymer rheology modifier can be selected from alkali-swellable / soluble acrylic emulsion polymers (ASE), hydrophobically modified alkali-swellable / soluble acrylic emulsion polymers (HASE), and hydrophobically modified ethoxylated polyurethane (HEUR) organic polymers.

[0049] Alkali-swellable / soluble emulsion (ASE) rheology modifiers are dispersions of insoluble acrylic polymers in water, which contain a high percentage of acidic groups throughout their polymer chains. When these acidic groups are neutralized, the resulting salt is hydrated. Depending on the concentration, molecular weight, and degree of crosslinking of the acidic groups, the salt swells or becomes completely water-soluble in the aqueous solution.

[0050] As the concentration of neutralizing polymer in aqueous formulations increases, the polymer chains swell, leading to an increase in viscosity.

[0051] ASE polymers can be synthesized from acid and acrylate comonomers and are typically prepared by emulsion polymerization. Exemplary commercially available ASE polymers include those sold as ACUSOL 810A, ACUSOL 830, ACUSOL 835, ACUSOL 842, and ACRYSOL RM-38.

[0052] Hydrophobically modified alkali-swellable / soluble emulsion (HASE) polymers are commonly used to modify the rheological properties of aqueous emulsion systems. Under the influence of alkali, organic, or inorganic substances, HASE particles gradually swell and expand to form a three-dimensional network through intermolecular hydrophobic aggregation between HASE polymer chains and / or with emulsion components. This network, combined with the hydrodynamic exclusion volume generated by the expanded HASE chains, produces the desired thickening effect. This network is sensitive to applied stress, decomposes under shear, and recovers upon stress relief.

[0053] HASE rheology modifiers can be derived from the following monomers: (a) olefinically unsaturated carboxylic acids, (b) nonionic olefinically unsaturated monomers, and (c) olefinically unsaturated hydrophobic monomers. Representative HASE polymer systems include those shown in EP 226097B1 (van Phung et al.), EP 705852B1 (Doolan et al.), U.S. Patent No. 4,384,096 (Sonnabend), and U.S. Patent No. 5,874,495 (Robinson).

[0054] Exemplary commercially available HASE polymers include those sold by Dow Chemical under the trade names ACUSOL 801S, ACUSOL 805S, ACUSOL 820, and ACUSOL 823.

[0055] ASE and HASE rheology modifiers are pH-triggered thickeners. Whether each emulsion polymer is water-swellable or water-soluble generally depends on its molecular weight. Both forms are acceptable. More details on the synthesis of ASE and HASE polymers can be found, for example, in U.S. Patent No. 9,631,165 (Droege et al.).

[0056] Hydrophobically modified ethoxylated polyurethane (HEUR) polymers are generally synthesized from alcohols, diisocyanates, and one or more polyalkylene glycols. HEURs are water-soluble polymers containing hydrophobic groups and are classified as associative thickeners due to the association of these hydrophobic groups with each other in water. Unlike HASEs, HEURs are nonionic and do not depend on a base for activating their thickening mechanism. When their hydrophobic groups associate with other hydrophobic components in a given formulation, they create intramolecular or intermolecular bonds. Generally, the strength of association depends on the number, size, and frequency of hydrophobic capping or blocking units. HEURs form micelles like ordinary surfactants. These micelles then connect with other components through association with their surfaces. This creates a three-dimensional network.

[0057] Exemplary commercially available HEUR polymers include those sold by Dow Chemical under the trade names ACUSOL 880, ACUSOL 882, ACRYSOL RM-2020, ACRYSOL RM-8W, and ACRYSOL RM-12W.

[0058] Further details about HEUR can be found in, for example, U.S. Patent Application Publication Nos. 2017 / 0198238 (Kensicher et al.) and 2017 / 0130072 (McCulloch et al.) and U.S. Patent Nos. 7,741,402 (Bobsein et al.) and 8,779,055 (Rabasco et al.).

[0059] Once the primer precursor is applied to the backing, and before curing, the abrasive particles are partially embedded in the primer precursor. Then, the curing of the primer precursor fixes the abrasive particles in the primer.

[0060] The abrasive particles available can be the result of a pulverizing operation (e.g., pulverized abrasive particles already classified according to shape and size) or a forming operation (i.e., shaped abrasive particles), wherein the abrasive precursor material is shaped (e.g., molded), dried, and transformed into a ceramic material. A combination of pulverized abrasive particles and forming abrasive particles can also be used. Abrasive particles can be in the form of, for example, single particles, agglomerates, composite particles, and mixtures thereof.

[0061] The abrasive particles should have sufficient hardness and surface roughness to function as pulverizing abrasive particles in the grinding process. Preferably, 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.

[0062] Suitable abrasive particles include, for example, pulverized abrasive particles comprising: molten alumina, heat-treated alumina, white molten alumina, ceramic alumina materials (such as ceramic alumina materials commercially available from 3M Company, St. Paul, Minnesota as 3M CERAMIC ABRASIVE GRAIN), brown alumina, blue alumina, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, garnet, titanium carbide, diamond, cubic boron nitride, garnet, molten alumina-zirconia, iron oxide, chromium oxide, zirconium oxide, titanium dioxide, tin oxide, quartz, feldspar, flint, corundum, ceramics prepared by the sol-gel method (e.g., α-alumina), and combinations thereof. Examples of abrasive particles prepared by a sol-gel method from which abrasive particles can be separated, and methods for preparing such particles, can be found in U.S. Patents 4,314,827 (Leitheiser et al.); 4,623,364 (Cottringer et al.); 4,744,802 (Schwabel); 4,770,671 (Monroe et al.); and 4,881,951 (Monroe et al.). It is also contemplated that the abrasive particles may comprise abrasive agglomerates, such as those described, for example, in U.S. Patent Nos. 4,652,275 (Bloecher et al.) or 4,799,939 (Bloecher et al.). In some embodiments, the abrasive particles may be surface-treated with a coupling agent (e.g., an organosilane coupling agent) or otherwise physically treated (e.g., iron oxide or titanium oxide) to enhance the adhesion of the pulverized abrasive particles to the binder. The abrasive particles may be treated prior to their bonding with the binder, or they may be surface-treated in situ by incorporating the coupling agent into the binder.

[0063] Preferably, the abrasive particles (and especially abrasive particles) comprise ceramic abrasive particles, such as polycrystalline α-alumina particles prepared, for example, by the sol-gel method. Ceramic abrasive particles composed of microcrystals of α-alumina, magnesium aluminum spinel, and rare earth hexaaluminates can be prepared using sol-gel α-alumina particle precursors according to methods described, for example, in U.S. Patent No. 5,213,591 (Celikkaya et al.) and U.S. Patent Application Publication Nos. 2009 / 0165394A1 (Culler et al.) and 2009 / 0169816A1 (Erickson et al.). Further details regarding methods for preparing sol-gel derived abrasive particles can be found, for example, in U.S. Patent Nos. 4,314,827 (Leitheiser), 5,152,917 (Pieper et al.), 5,435,816 (Spurgeon et al.), 5,672,097 (Hoopman et al.), 5,946,991 (Hoopman et al.), 5,975,987 (Hoopman et al.), and 6,129,540 (Hoopman et al.), as well as U.S. Patent Application Publication No. 2009 / 0165394A1 (Culler et al.).

[0064] In some preferred embodiments, the available abrasive particles (particularly in the case of abrasive particles) can be shaped abrasive particles, as seen in U.S. Patent Nos. 5,201,916 (Berg), 5,366,523 (Rowenhorst (Re 35,570)), and 5,984,988 (Berg). U.S. Patent No. 8,034,137 (Erickson et al.) describes alumina abrasive particles that have been shaped to a specific form and then crushed to form fragments that retain a portion of their initial shape characteristics. In some embodiments, the abrasive particles are precisely shaped (i.e., the shape of the particles is at least partially determined by the shape of the cavities in the production tools used to prepare them). Details regarding such abrasive particles and methods for their preparation can be found, for example, in U.S. Patent Nos. 8,142,531 (Adefris et al.), 8,142,891 (Culler et al.), 8,142,532 (Erickson et al.), 9,771,504 (Adefris), and U.S. Patent Application Publications 2012 / 0227333 (Adefris et al.), 2013 / 0040537 (Schwabel et al.), and 2013 / 0125477 (Adefris). A particularly useful, precisely shaped abrasive particle is a sheet shape with three sidewalls, any one of which can be straight or concave and can be vertical or inclined relative to the sheet base; for example, shapes described in the references cited above. Figure 2An exemplary example of such precisely shaped abrasive particles 200 is shown.

[0065] Surface coatings on abrasive particles can be used to improve adhesion between the abrasive particles and the binder material, or to facilitate electrostatic deposition of the abrasive particles. In one embodiment, the surface coating described in U.S. Patent 5,352,254 (Celikkaya) may be used in an amount of 0.1% to 2% of the weight of the abrasive particles. Such surface coatings are described in U.S. Patent Nos. 5,213,591 (Celikkaya et al.), 5,011,508 (Wald et al.), 1,910,444 (Nicholson), 3,041,156 (Rowse et al.), 5,009,675 (Kunz et al.), 5,085,671 (Martin et al.), 4,997,461 (Markhoff-Matheny et al.), and 5,042,991 (Kunz et al.). Additionally, the surface coating can prevent the formed abrasive particles from being capped. "Capping" is a term used to describe the phenomenon where metal particles from a workpiece being ground are welded onto the top of abrasive particles. Surface coatings that perform the above function are known to those skilled in the art.

[0066] In some implementations, the length and / or width of the abrasive particles may be selected to be in the range of 0.1 micrometers to 3.5 millimeters (mm), more typically in the range of 0.05 mm to 3.0 mm, and more typically in the range of 0.1 mm to 2.6 mm, but other lengths and widths may also be used.

[0067] Abrasive particles with a thickness ranging from 0.1 micrometers to 1.6 millimeters, and more typically from 1 micrometer to 1.2 millimeters, can be selected, but other thicknesses are also possible. In some embodiments, the abrasive particles may have an aspect ratio (length to thickness ratio) of at least 2, 3, 4, 5, 6, or greater.

[0068] Abrasive particles can be independently classified by size according to industry-recognized grading standards. Exemplary industry-recognized grading standards include those issued by ANSI (American National Standards Institute), FEPA (Federation of European Abrasive Manufacturers), and JIS (Japanese Industrial Standards). These industry-recognized 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, and FEPA P150. P320, FEPA P400, FEPA P500, FEPA P600, FEPA P800, FEPA P1000, FEPA P1200; FEPA F8, FEPA F12, FEPA F16 and FEPA F24; and JIS 8, JIS 12, JIS 16, JIS 24, JIS 36, JIS 46, JIS 54, JIS 60. JIS 80, JIS 100, JIS 150, JIS 180, JIS 220, JIS 240, JIS 280, JIS 320, JIS 360, JIS 400, JIS 600, JIS 800, JIS 1000, JIS 1500, JIS 2500, JIS 4000, JIS6000, JIS 8000 and JIS 10,000. More typically, the sizes of pulverized alumina particles and alumina-based abrasive particles prepared by seedless sol-gel methods are independently set to ANSI 60 and 80 or FEPA F36, F46, F54 and F60 or FEPA P60 and P80 grading standards.

[0069] Alternatively, the abrasive particles may be tested using ASTM E-11, "Standard Specification for Wire Cloth and Sieves for Testing Purposes." ASTM E-11 specifies the design and construction requirements for test sieves that use a medium of woven wire mesh mounted in a frame to classify materials according to a specified particle size. -18+20 is a typical designation, meaning that the formed abrasive particles can pass through an ASTM E-11 18-mesh test sieve but may remain on an ASTM E-11 20-mesh test sieve. In one embodiment, the formed abrasive particles have a particle size such that most particles pass through an 18-mesh test sieve and may remain on 20, 25, 30, 35, 40, 45, or 50-mesh test sieves. In various implementations, the formed abrasive particles may have nominal sieve grades including: -18+20, -20+25, -25+30, -30+35, -35+40, -40+45, -45+50, -50+60, -60+70, -70+80, -80+100, -100+120, -120+140, -140+170, -170+200, -200+230, -230+270, -270+325, -325+400, -400+450 / -450+500, or -500+635. Alternatively, custom mesh sizes such as -90+100 may be used.

[0070] A re-adhesive layer is generally formed by coating and at least partially curing a re-adhesive layer precursor comprising a thermosetting / curable composition onto a base layer and abrasive particles, and then at least partially curing the re-adhesive layer precursor. Suitable re-adhesive layer precursors / re-adhesive layers may have compositions that are the same as or different from the compositions contained in the base layer precursors / base layers described above.

[0071] In some embodiments, the primer precursor comprises a methyl phenolic resin and an organic polymer rheology modifier, as described above in the case of primer precursor / primer.

[0072] The topcoat precursor comprises a water-based epoxy resin and an organic polymer rheology modifier as described above.

[0073] Exemplary water-based epoxy resins and their precursors (e.g., water-dispersible epoxy resins) include: epoxy resins marketed by Hexion Corporation (Columbus, Ohio), such as EPI-Rez Resin WD-510 water-dispersible liquid resin, and those traded under the names EPI-REZ Resin 3510-W-60 and EPI-REZ Resin 7510-W-60, EPI-REZ Resin 3515-W-60, EPI-REZ Resin 3520-WY-55, EPI-REZ Resin 6520-WH-53, EPI-REZ Resin 7520-WD-52, EPI-REZ Resin 3522-W-60, EPI-REZ Resin 3540-WY-55, and EPI-REZ Resin Resin dispersions of 3546-WH-53, EPI-REZ Resin 5520-W-60, EPI-REZ Resin 5522-WY-55, EPI-REZ Resin 5003-W-55, EPON Resin RSW-2801, EPI-REZ Resin 5108-W-60, and EPI-REZ Resin 6006-W-68; epoxy resins marketed by Olin Corp., Clayton, Missouri under the trade names DER900, DER913, DER915, DER916, and DER917; and epoxy resin marketed by Allnex Corp., Frankfurt, Germany under the trade name BECKOPOX VEP 2381W / 55WA. Some preferred water-based epoxy resins include diglycidyl ether of bisphenol A.

[0074] In some embodiments, the topcoat layer is formed from a composition comprising a water-based epoxy resin, a nonionic emulsifier, water, an imidazole curing agent, a potassium tetrafluoroborate abrasive aid, and a dispersant. Once the epoxy dispersion is applied to the coated abrasive product, it can be heated to induce polymerization of the epoxy resin. Heating is typically carried out at a temperature of about 80°C to about 130°C, preferably about 105°C to about 115°C, for a period of about 10 minutes to about 250 minutes, preferably about 20 minutes to about 50 minutes. Further details regarding the water-based epoxy resin and the topcoat layer containing it can be found, for example, in U.S. Patent No. 5,556,437 (Lee et al.).

[0075] Typically, the top adhesive layer also contains at least one grinding aid, however, this is not mandatory.

[0076] Grinding aids are materials that significantly influence the chemical and physical processes of grinding, thereby improving performance. Grinding aids encompass a wide variety of materials and can be inorganic or organic-based. Examples of chemical groups in grinding aids include waxes, organohalides, halide salts, metals and their alloys, and metal salts of stearates and stearates. Organohalides typically decompose during grinding, releasing halogen acids or gaseous halides. Examples of such materials include chlorinated paraffins, such as naphthalene tetrachloride, naphthalene pentachloride, and polyvinyl chloride. 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 metals include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium.

[0077] Other miscellaneous grinding aids include sulfur, organosulfur compounds, graphite, and metal sulfides. Combinations of different grinding aids can be used, and in some cases, this can produce a synergistic effect.

[0078] Grinding aids are particularly useful in coated abrasives. In coated abrasive articles, grinding aids are typically used in the top coat, which is applied over the surface of the top coat. However, sometimes grinding aids are added to the top coat. Typically, the amount of grinding aid incorporated into coated abrasive articles ranges from about 50 g / m² to 800 g / m². 2 ), preferably about 80g / m 2 Up to 475g / m 2 However, this is not necessarily the case.

[0079] The topcoat typically has a basis weight of 5 g / m² to 1100 g / m², preferably 50 g / m² to 700 g / m², and more preferably 250 g / m² to 600 g / m², but this is not mandatory. The basis weights of the base coat, top coat, and optional topcoat typically depend at least in part on the abrasive grit size and the specific type of abrasive article.

[0080] The base coat, top coat, and top coat are formed by at least partially curing the respective precursors (i.e., the base coat precursor, the top coat precursor, and the top coat precursor).

[0081] The primer, topcoat, and topcoat, as well as 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 zirconate aluminates), plasticizers, suspending agents, etc. The amounts of these optional additives are selected to provide preferred properties. Coupling agents can improve adhesion to abrasive particles and / or fillers. The curable composition may be thermosetting, radiation-curing, or a combination thereof.

[0082] The base coat, top coat, and top coat, as well as their precursors, may also contain filler materials, diluted abrasive particles (e.g., as described below), or grinding aids, typically in the form of particulate materials. Typically, the particulate materials are inorganic. Examples of fillers that can be used in this disclosure include: 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 bulbs, and glass fibers), silicates (e.g., talc, clay, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminate, sodium silicate), metal sulfates (e.g., calcium sulfate, barium sulfate, sodium sulfate, sodium aluminum 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).

[0083] Further details regarding coated abrasive articles and methods of their manufacture can be found, for example, in U.S. Patent 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).

[0084] The coated abrasive articles according to this disclosure can be used, for example, to grind workpieces. Such methods may include: bringing the abrasive particles according to this disclosure into frictional contact with a workpiece surface, and moving at least one of the coated abrasive particles and the workpiece surface relative to the other to grind at least a portion of the workpiece surface. Grinding methods using the coated abrasive articles according to this disclosure range from, for example, rough grinding (i.e., high-pressure high-cutting) to polishing (e.g., polishing medical implants with coated abrasive belts), wherein the latter is typically accomplished using finer grades of abrasive particles (e.g., ANSI 220 and finer grades). The size of the abrasive particles used for a particular grinding application will be apparent to those skilled in the art.

[0085] Grinding can be performed dry or wet. For wet grinding, the introduced liquid can be provided in the form of a light mist to a full stream of water. Examples of commonly used liquids include water, water-soluble oils, organic lubricants, and emulsions. These liquids can be used to reduce the heat associated with grinding and / or as lubricants. The liquid may contain trace amounts of additives, such as bactericides, defoamers, etc.

[0086] Examples of workpieces include aluminum, carbon steel, low-carbon steel (e.g., 1018 and 1045 low-carbon steel), tool steel, stainless steel, hardened steel, titanium, glass, ceramics, wood, wood-based materials (e.g., plywood and particleboard), painted surfaces, varnished surfaces, and organic-coated surfaces. The force applied during grinding is typically in the range of about 1 to about 100 kg, but other pressures may also be used.

[0087] This disclosure selects an implementation scheme.

[0088] In a first embodiment, this disclosure provides a method for preparing coated abrasive articles, the method comprising:

[0089] A backing having opposite first and second main surfaces is provided, wherein an adhesive base layer is disposed on at least a portion of the first main surface and abrasive particles are bonded to the backing, and further wherein an adhesive overlay is disposed on the adhesive base layer and at least a portion of the abrasive particles;

[0090] as well as

[0091] A topcoat layer precursor is coated onto at least a portion of the adhesive layer, and the topcoat layer precursor is at least partially cured to provide the topcoat layer.

[0092] The topcoat precursor contains a water-based epoxy resin and an organic polymer rheology modifier.

[0093] The organic polymer rheology modifier comprises an alkali-swellable / soluble polymer, and wherein, based on solids, the amount of the water-based epoxy resin accounts for 75% to 99.99% by weight of the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

[0094] In a second embodiment, this disclosure provides a method according to the first embodiment, wherein the curing of the at least partially cured topcoat layer precursor is carried out in a suspended oven.

[0095] In a third embodiment, this disclosure provides a method according to a first or second embodiment, wherein the topcoat precursor has a basis weight of 5 to 1100 grams per square meter.

[0096] In a fourth embodiment, this disclosure provides a method according to any one of the first to third embodiments, wherein the organic polymer rheology modifier is selected from alkali-swellable / soluble acrylic polymers, hydrophobically modified alkali-swellable / soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof.

[0097] In a fifth embodiment, this disclosure provides a method according to any one of the first to fourth embodiments, wherein, based on solids, the amount of the water-based epoxy resin is 85% to 99.99% by weight of the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

[0098] In a sixth embodiment, this disclosure provides a method according to any one of the first to fifth embodiments, wherein the abrasive particles comprise shaped abrasive particles.

[0099] In a seventh embodiment, this disclosure provides a method according to a sixth embodiment, wherein the shaped abrasive particles comprise precisely shaped abrasive particles.

[0100] In an eighth embodiment, this disclosure provides a method according to a sixth embodiment, wherein the shaped abrasive particles comprise precisely shaped triangular flakes.

[0101] In a ninth embodiment, this disclosure provides a coated abrasive article comprising:

[0102] A backing having opposite first and second main surfaces;

[0103] An adhesive base layer is disposed on at least a portion of the first main surface and bonds abrasive particles to the backing.

[0104] A backing layer, which covers at least a portion of the base adhesive layer and the abrasive particles; and

[0105] Top adhesive layer, which is disposed on the top adhesive layer.

[0106] The topcoat layer comprises at least partially cured epoxy resin and an organic polymer rheology modifier, wherein the amount of the at least partially cured epoxy resin is from 75% to 99.99% by weight of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

[0107] In a tenth embodiment, this disclosure provides a coated abrasive article according to a ninth embodiment, wherein the organic polymer rheology modifier is selected from alkali-swellable / soluble acrylic polymers, hydrophobically modified alkali-swellable / soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof.

[0108] In the eleventh embodiment, this disclosure provides a coated abrasive article according to the ninth or tenth embodiment, wherein the amount of the at least partially cured epoxy resin is 85% to 99.99% by weight of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

[0109] In the twelfth embodiment, this disclosure provides a coated abrasive article according to any one of the ninth to eleventh embodiments, wherein the abrasive particles comprise shaped abrasive particles.

[0110] In a thirteenth embodiment, this disclosure provides a coated abrasive article according to a twelfth embodiment, wherein the formed abrasive particles comprise precisely shaped abrasive particles.

[0111] In the fourteenth embodiment, this disclosure provides a coated abrasive article according to the twelfth embodiment, wherein the shaped abrasive particles comprise precisely shaped triangular flakes.

[0112] The objects and advantages of this disclosure are further illustrated by the following non-limiting embodiments, but the specific materials and quantities referenced in these embodiments, as well as other conditions and details, should not be regarded as undue limitations on this disclosure.

[0113] Example

[0114] Unless otherwise stated, all parts, percentages, ratios, etc., in the embodiments and the remainder of this specification are by weight. Table 1 below reports the materials used in the embodiments.

[0115] Table 1

[0116]

[0117]

[0118] Resin preparation

[0119] Comparison of topcoat precursors CSSR-A

[0120] To a 3-liter plastic container, combine 438 g ER, 173 g water, 8.7 g ADD4, 55.1 g ADD5, 13.8 g ADD6, 18.1 g SF1, 1.9 g SF2, and 319.4 g LR. Mix with a top-mounted mechanical mixer for 10 minutes. Then, add 1972 g FIL2 over a 15-minute period. Continue mixing with a top-mounted mixer for another 15 minutes.

[0121] Comparison of topcoat precursors CSSR-B 、 CSSR-C 、 CSSR-D and CSSR-E

[0122] 99.5 g of CSSR-A and 0.25 g of FIL1 were added to a 118 ml wide-mouth glass flask. The mixture was stirred for 5 minutes using a top stirrer to prepare the comparative topcoat precursor CSSR-B. Comparative topcoat precursors CSSR-C, CSSR-D, and CSSR-E were prepared in a similar manner, and their formulations are described in Table 2.

[0123] Topcoat precursor ESSR-1 and ESSR-2

[0124] Add 99.5 g of CSSR-A and 0.5 g of ADD 2 to a 118 ml glass container. Stir the mixture for 5 minutes using a top stirrer to prepare topcoat precursor 1 (ESSR-1). Exemplary topcoat precursor 2 (ESSR-2) is prepared in a similar manner, and the formulation is described in Table 2.

[0125] Topcoat precursor ESSR-3 and ESSR-4

[0126] Add 99.5 g of CSSR-A and 0.5 g of ADD to a 118 ml glass jar. Stir the mixture for 5 minutes using a top stirrer to prepare the topcoat precursor ESSR-3. The topcoat precursor ESSR-4 example was prepared in a similar manner, and the formulation is described in Table 2 below.

[0127] Table 2

[0128]

[0129] Inclined plane flow test

[0130] The tilted plane flow test involves placing a drop of 0.1 g of resin onto a horizontally placed glass slide at a specified temperature, and then rapidly tilting the slide for 1 minute on a tilting device set at an angle of 48.7° (see [link to test]). Figure 1 , 2 (See Tables 2 and 3). Record the distance the resin travels in one minute in millimeters (mm). The smaller the distance, the less likely the resin will overflow and cause bottom loop puddling in the hanging curing oven. Data analysis ( Figure 1 , Figure 2 and Table 2, Figure 3 The thixotropic properties of ESSRs-1, 2, 3, and 4 are clearly illustrated. In fact, these examples show an improvement of 10 to 20 times relative to the comparative examples (CSSRs-A, B, C, and D) based on 100% solids weight.

[0131] Table 3 below shows the results of inclined plane flow tests for various resins at room temperature (RT) and 41°C.

[0132] Table 3

[0133]

[0134] Primer resin MR

[0135] Prepare the primer resin by adding 7812 g PF, 6823 g FIL1, and 364 g water to a 17-liter container. Mix the resin at room temperature for 30 minutes using a top-mounted stirrer.

[0136] Composite resin SR1

[0137] To prepare the laminating resin, add 11,100 g PF, 5,800 g FIL1, 420 g ADD5, and 2,000 g water to a 17-liter container. Mix the resin at room temperature for 30 minutes using a top-mounted stirrer.

[0138] Composite resin SR2

[0139] To prepare the laminating resin, add 11,100 g PF, 5,800 g FIL1, 420 g ADD5, 118 g ADD3, and 2,000 g water to a 17-liter container. Mix the resin at room temperature for 30 minutes using a top-mounted stirrer.

[0140] Topcoat precursor ESSR-5

[0141] An exemplary topcoat precursor, ESSR-5, was prepared by adding 18,180 g of CSSR-A, 92 g of ADD2, 92 g of ADD3, and 614 g of water to a 17-liter container and mixing for 30 minutes using a top-mounted mechanical stirrer.

[0142] Coated abrasives are more suitable for top coating CSSR-F

[0143] The coated abrasive examples and comparative examples were prepared as follows: Primer resin MR was roller-coated onto a 30.48 cm wide continuous polyester backing (as described in Example 12 of U.S. Patent No. 6,843,815 by Thurber et al.) at a coating weight of 210 g / m² (gsm), followed by electrostatic coating of mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90°C for 90 min and at 102°C for 60 min. The resulting material was then roller-coated with topcoat resin SR1 at a coating weight of 567 g / m² (gsm). This material was cured at 90°C for 60 min and at 102°C for 60 min. The resulting material was then roller-coated with comparative topcoat precursor CSSR-A at a coating weight of 567 g / m² (gsm). Finally, the material was cured at 90°C for 60 min, at 102°C for 12 h, and at 109°C for 1 h.

[0144] Topcoat of Coated Abrasive Examples ESSR-5

[0145] The coated abrasive examples and comparative examples were prepared as follows: Primer resin MR was roller-coated onto a 30.48 cm wide continuous polyester backing (as described in Example 12 of U.S. Patent No. 6,843,815 by Thurber et al.) at a coating weight of 210 g / m² (gsm), followed by electrostatic coating of 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 resulting material was then roller-coated with topcoat resin SR2 at a coating weight of 567 g / m² (gsm). This material was cured at 90°C for 60 minutes and at 102°C for 60 minutes. The resulting material was then roller-coated with comparative topcoat precursor ESSR-5 at a coating weight of 567 g / m² (gsm). Finally, the material was cured at 90°C for 60 minutes, at 102°C for 12 hours, and at 109°C for 1 hour.

[0146] Comparison of coated abrasive topcoat precursors

[0147] like Figure 3 and Figure 4 As shown, the topcoat precursor CSSR-F was used for comparison. Figure 3 The coated abrasive article prepared as shown in the figure exhibits a bottom loop adhesion problem, while in addition to using the top adhesive layer precursor ESSR-5 ( Figure 4 Other coated abrasive products (as shown in the image) do not have this problem.

[0148] All references, patents, and patent applications cited herein are incorporated in a consistent manner. In the event of any inconsistency or contradiction between the incorporated references and this application, the information in this application shall prevail. The foregoing description, given to enable those skilled in the art to practice this disclosure protected by the claims, should not be construed as limiting the scope of this disclosure, which is defined by the claims and all their equivalents.

Claims

1. A method for preparing coated abrasive articles, the method comprising: A backing having opposite first and second main surfaces is provided, wherein an undercoat layer is disposed on at least a portion of the first main surface and bonds abrasive particles to the backing, and further wherein a topcoat layer is disposed on the undercoat layer and at least a portion of the abrasive particles; as well as A topcoat layer precursor is coated onto at least a portion of the adhesive layer, and the topcoat layer precursor is cured at least partially to provide the topcoat layer. The topcoat precursor comprises a water-based epoxy resin and an organic polymer rheology modifier, wherein the organic polymer rheology modifier is selected from alkali-swellable / soluble acrylic polymers, hydrophobically modified alkali-swellable / soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof, and wherein, based on solids, the amount of the water-based epoxy resin is from 75% to 99.99% by weight of the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

2. The method of claim 1, wherein the curing of the topcoat layer precursor is performed in a suspended oven.

3. The method according to claim 1, wherein the topcoat precursor has a basis weight of 5 to 1100 grams per square meter.

4. The method according to claim 1, wherein, On a solids basis, the amount of the water-based epoxy resin accounts for 85% to 99.99% by weight of the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

5. The method of claim 1, wherein the abrasive particles comprise shaped abrasive particles.

6. The method of claim 5, wherein the shaped abrasive particles comprise precisely shaped abrasive particles.

7. The method of claim 5, wherein the shaped abrasive particles comprise precisely shaped triangular flakes.

8. A coated abrasive article, comprising: A backing having opposite first and second main surfaces; A base layer is disposed on at least a portion of the first main surface and bonds abrasive particles to the backing; A backing layer, the backing layer covering at least a portion of the base adhesive layer and the abrasive particles; and A top adhesive layer, wherein the top adhesive layer is disposed on the top adhesive layer. The topcoat layer comprises at least partially cured epoxy resin and an organic polymer rheology modifier, wherein the organic polymer rheology modifier is selected from alkali-swellable / soluble acrylic polymers, hydrophobically modified alkali-swellable / soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof, and wherein the amount of the at least partially cured epoxy resin is from 75% to 99.99% by weight of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

9. The coated abrasive article according to claim 8, wherein the amount of the at least partially cured epoxy resin is from 85% to 99.99% by weight of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

10. The coated abrasive article according to claim 8, wherein the abrasive particles comprise shaped abrasive particles.

11. The coated abrasive article of claim 10, wherein the shaped abrasive particles comprise precisely shaped abrasive particles.

12. The coated abrasive article of claim 10, wherein the shaped abrasive particles comprise precisely shaped triangular flakes.

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