CN116133794A

CN116133794A - Coated abrasive article and method of making the same

Info

Publication number: CN116133794A
Application number: CN202180059599.4A
Authority: CN
Inventors: 欧内斯特·L·瑟伯; 格雷戈里·P·索伦森; 伊利娅·戈罗迪舍; 托马斯·J·纳尔逊; 李军廷; 丹尼尔·M·伦茨
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2020-07-28
Filing date: 2021-07-20
Publication date: 2023-05-16
Also published as: US20230286112A1; EP4188646A1; WO2022023879A1

Abstract

A coated abrasive article comprising a backing having opposed 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 overlying the make layer and at least a portion of the abrasive particles; and a top adhesive layer arranged on the compound adhesive layer. The supersize layer comprises an at least partially cured water-based epoxy resin and an organic polymer 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 polymer rheology modifier. A method of making the coated abrasive article is also disclosed.

Description

Coated abrasive article and method of making the same

Technical Field

The present disclosure relates to abrasive articles comprising an epoxy top coat binder material and methods of making the same.

Background

Abrasive articles typically comprise abrasive particles (also referred to as "abrasive particles") retained in a binder. During the manufacture of various types of abrasive articles, abrasive particles are deposited on the binder material precursor in an oriented manner (e.g., by electrostatic coating or by some mechanical placement technique). Typically, the most desirable orientation of the abrasive particles is substantially perpendicular to the surface of the backing.

For some coated abrasive articles (e.g., abrasive discs), the backing is a relatively dense planar substrate (e.g., vulcanized fiber or woven or knit fabrics, optionally treated with an impregnating agent to increase durability). A make layer precursor (or make layer) containing a first binder material precursor is applied to the backing, and abrasive particles are then partially embedded in the make layer precursor. In many cases, the abrasive particles are embedded in the make coat precursor in a certain degree of orientation; for example by electrostatic coating or by mechanical placement techniques. The make coat precursor is then at least partially cured to retain the abrasive particles as the make coat precursor (or make coat) containing the second binder material precursor overlies the at least partially cured make coat precursor and the abrasive particles. Next, if the size layer precursor and the make layer precursor are not sufficiently cured, both are cured to form the coated abrasive article.

In some cases, the top glue layer may be formed from a corresponding top glue layer precursor (size layer).

For thermally cured make coat precursors, the coated abrasive product is typically manufactured as a continuous web that is dried and cured in a pendant oven, where the web is overlaid on a hanger bar that is advanced through the oven.

Disclosure of Invention

During curing in a pendant oven, flow of the top coat due to gravity can be a problem, particularly if the abrasive particles are arranged such that flow is not impeded by the abrasive particles. However, the recent trend toward precise placement and/or orientation of abrasive particles has increased the need for solutions to the gravity flow problem described above.

The present disclosure overcomes such problems by using a make coat precursor comprising a water-based curable epoxy resin and a rheology modifier suitable for making abrasive articles. Rheology modifiers include organic polymer rheology modifiers comprising alkali swellable/soluble polymers. It has now been found that these organic polymeric rheology modifiers provide better control of the flow of the make coat precursor than previously used techniques.

Organic polymeric rheology modifiers are known to impart pseudoplastic flow characteristics. 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 for latex paints, personal care products, and drilling muds. As used herein, the term "alkali swellable/soluble emulsion (ASE) polymer" specifically excludes hydrophobically modified alkali swellable/soluble emulsion (HASE) polymers.

In a first aspect, the present disclosure provides a method of making a coated abrasive article, the method comprising:

providing a backing having opposed first and second 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, further wherein a size layer is disposed on at least a portion of the make layer and the abrasive particles;

and

Coating a make layer precursor on at least a portion of the size layer, and at least partially curing the make layer precursor to provide a make layer,

wherein the top coat precursor comprises a water-based epoxy resin and an organic polymer rheology modifier,

wherein the organic polymer rheology modifier comprises an alkali swellable/soluble polymer, and wherein the amount of the water-based epoxy resin is from 75 wt% to 99.99 wt% of the total weight of the water-based epoxy resin and the organic polymer rheology modifier on a solids basis.

In a second aspect, the present disclosure provides a coated abrasive article comprising:

a backing having opposed 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 overlying the make layer and at least a portion of the abrasive particles; and

a top adhesive layer arranged on the compound adhesive layer,

wherein the supersize layer comprises an at least partially cured epoxy resin and an organic polymer 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 polymer rheology modifier.

As used herein:

by "alkali swellable" is meant capable of at least partially swelling in an aqueous solution of a water soluble base having a pH greater than 7;

"alkali-swellable/soluble" means at least one of alkali-swellable or alkali-soluble (i.e., alkali-swellable and/or alkali-soluble);

unless explicitly indicated otherwise, "polymer" refers to an organic polymer; and is also provided with

"Water-based" means dissolved or dispersed in a liquid medium having water as a major component.

A further understanding of the nature and advantages of the present disclosure will be realized when the particular embodiments and the appended claims are considered.

Drawings

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 an exemplary precisely-shaped abrasive particle 200.

FIG. 3 is a digital photograph of a coated abrasive article prepared with comparative make layer precursor CSSR-F.

FIG. 4 is a digital photograph of a coated abrasive article prepared with a make layer precursor ESSR-5.

It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that fall within the scope and spirit of the principles of this disclosure. The figures may not be drawn to scale.

Detailed Description

An exemplary embodiment of a coated abrasive article according to the present disclosure is shown in fig. 1. Referring now to fig. 1, a coated abrasive article 100 has a backing 120 and an abrasive layer 130. The abrasive layer 130 comprises abrasive particles 140 secured to a major surface 170 of the backing 120 by a make coat 150 and a size coat 160. The top glue layer 180 covers the size layer 160.

For example, coated abrasive articles according to the present disclosure may include additional layers such as a backing antistatic treatment layer, and/or may also include an attachment layer, if desired.

For example, useful backings include backings known in the art for use in preparing coated abrasive articles. Typically, but not necessarily, the backing has two opposing major surfaces. 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, although thicknesses outside of these ranges may also be used. Generally, the backing should be strong enough to resist tearing or other damage during the abrading process. 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., needled, melt-spun, spun-bonded, hydroentangled, or melt-blown nonwoven fabrics), knit fabrics, stitch-bonded fabrics, and/or woven fabrics; a scrim; a polymer film; their treated form; and combinations of two or more of these materials.

The fabric backing may be made of any known fibers, whether natural fibers, synthetic fibers, or blends of natural and synthetic fibers. Examples of useful fibrous materials include fibers or yarns comprising polyesters (e.g., polyethylene terephthalate), polyamides (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. Usable fibers may be of natural material or recycled or waste material recovered, for example, from apparel cutting, carpet manufacturing, fiber manufacturing, or textile processing. Useful fibers may be homogenous or be a composite such as bicomponent fibers (e.g., co-spun sheath-core fibers). These fibers may be drawn 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 the range of 100 grams per square meter to 1250 grams per square meter (gsm), more typically in the range of 450gsm to 600gsm, and even more typically in the range of 450gsm to 575 gsm. In many embodiments (e.g., wear strips and plates), the backing typically has good flexibility; however, this is not necessary (e.g., vulcanized fiber discs). To facilitate adhesion of the binder resin to the backing, one or more surfaces of the backing may be modified by known methods, including corona discharge, ultraviolet light irradiation, electron beam irradiation, flame discharge, and/or roughening.

The primer layer is formed by coating a primer layer precursor on a major surface of the backing and at least partially curing the primer layer precursor. The primer layer precursor comprises a thermosetting/curable composition. Examples of suitable thermosetting/curable resins that can be used for the primer layer precursor include, for example, free-radically polymerizable monomers and/or oligomers, epoxy resins, acrylic resins, polyurethane 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 resins can be cured, for example, by heat and/or by exposure to radiation. Depending on the curable resin, the catalyst and/or initiator (e.g., thermal initiator and/or photoinitiator) is typically included in an amount of up to 10 weight percent of the primer layer precursor. The choice of catalyst and/or initiator is within the ability of one of ordinary skill in the art. Additional details regarding primer layer precursors can 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 make coat precursor and make coat 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.

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

The organic polymer rheology modifier comprises an alkali swellable/soluble polymer. The amount of resole is from 75% to 99.99% by weight of the total weight of resole and organic polymer rheology modifier on a solids basis.

Generally, phenolic resins are formed by the condensation of phenol and formaldehyde and are generally classified as resoles or novolac phenolic resins. The novolac phenolic resin is acid catalyzed and the molar ratio of formaldehyde to phenol is less than 1:1. Resole/resole phenolic resins may be catalyzed with basic catalysts and the molar ratio of formaldehyde to phenol is greater than or equal to one, typically between 1.0 and 3.0, so that pendant hydroxymethyl groups are present. Basic catalysts suitable for catalyzing the reaction between the aldehyde and phenol components of the resole resin include sodium hydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide, organic amines, and sodium carbonate, all of which act as catalyst solutions dissolved in water.

Resoles are typically coated as solutions with water and/or organic solvents (e.g., alcohols). Typically, the solution contains solids in an amount of about 70 wt% to about 85 wt%, although other concentrations may 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 viscosity of the resulting phenolic resin is too high, which often leads to processing problems.

Phenolic resins are well known and readily available from commercial sources. Examples of commercially available resoles useful in the practice of the present disclosure include those sold by Du Leici company (Durez Corporation) under the trade names varum (e.g., 29217, 29306, 29318, 29338, 29353); those sold under the trade name AEROFENE (e.g., AEROFENE 295) by a Shi Lande Chemical company of barton, florida (Ashland Chemical co., barnow, florida); and those sold under the trade name PHENOLITE (e.g., PHENOLITE TD-2207) by Jiangnan chemical Co., ltd (Kangnam Chemical Company Ltd. Of Seoul, south Korea) of Korea.

An overview discussion of phenolic resins and their manufacture is given in the following references: kirk-Othmer, encyclopedia of chemical technology,4th edition, john Wiley national publication, 1996, new York, volume 18, pages 603-644 (Kirk-Othmer, encyclopedia of Chemical Technology,4th Ed., john Wiley & Sons,1996,New York,Vol.18,pp.603-644).

In addition to the resole, the curable composition contains an organic polymer rheology modifier comprising an alkali swellable/soluble polymer. The curable composition comprises a resole (typically diluted with water) and an organic polymer rheology modifier comprising an alkali swellable/soluble polymer. Wherein the amount of resole is from 75 wt.% to 99.99 wt.% (preferably from 82 wt.% to 99.99 wt.%, and even more preferably from 88 wt.% to 99.99 wt.%) based on solids, of the total weight of resole and organic polymer rheology modifier. Thus, the curable composition comprises from 0.01 to 25 wt%, preferably from 0.01 to 18 wt%, and more preferably from 0.01 to 12 wt% of the organic polymer rheology modifier, based on the total weight of the resole and the organic polymer rheology modifier. Combinations of more than one resole and/or more than one organic polymer rheology modifier may be used if desired.

Suitable alkali swellable/soluble polymers for use 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).

For example, the organic polymer rheology modifier may be selected from the group consisting of alkali swellable/soluble acrylic emulsion polymer (ASE), hydrophobically modified alkali swellable/soluble acrylic emulsion polymer (HASE), and hydrophobically modified ethoxylated polyurethane (HEUR) organic polymers.

An alkali-swellable/soluble emulsion (ASE) rheology modifier is a dispersion of an insoluble acrylic polymer in water, the insoluble acrylic polymer having a high percentage of acid groups distributed throughout its polymer chain. When these acidic groups are neutralized, the salt formed is hydrated. Depending on the concentration of acidic groups, molecular weight and degree of crosslinking, the salt swells or becomes completely water-soluble in aqueous solution.

As the concentration of neutralized polymer in the aqueous formulation increases, the polymer chains swell, resulting in an increase in viscosity.

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, ACUSOL 835, ACUSOL 842, and acuosol RM-38.

Hydrophobically modified alkali swellable/soluble emulsion (HASE) polymers are commonly used to modify the rheology of aqueous emulsion systems. The HASE particles gradually swell and expand under the influence of a base, organic or inorganic substance by intermolecular hydrophobic packing between HASE polymer chains and/or with emulsion components to form a three-dimensional network. The network combines with the hydrodynamic exclusion volumes created by the swollen HASE chains to create the desired thickening effect. The network is sensitive to applied stresses, breaks down under shear, and recovers upon stress relief.

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 the HASE polymer systems shown in EP 226097B1 (van lug et al), EP 705852B1 (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 HASE polymers sold by Dow Chemical company (Dow Chemical) under the trade names ACUSOL 801S, ACUSOL 805S, ACUSOL and ACUSOL 823.

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. Further details on the synthesis of ASE and HASE polymers can be found, for example, in U.S. Pat. No. 9,631,165 (Droege et al).

Hydrophobically modified ethoxylated polyurethane (HEUR) polymers are generally synthesized from an alcohol, a diisocyanate, and one or more polyalkylene glycols. HEUR is a water-soluble polymer containing hydrophobic groups and is classified as an associative thickener because the hydrophobic groups associate with each other in water. Unlike HASE, HEUR is a nonionic substance and does not rely on a base to activate the thickening mechanism. When their hydrophobic groups associate with other hydrophobic components in a given formulation, they create an intramolecular or intermolecular linkage. The strength of the association is generally dependent on the number, size and frequency of hydrophobic capping or closure units. HEUR will form micelles as with conventional surfactants. The micelle is then linked between the other components by association with its surface. This creates a three-dimensional network.

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.

Further details regarding HEUR can be found, for example, in U.S. patent application publication Nos. 2017/0198238 (Kensicher et al) and 2017/013092 (McCulloch et al) and U.S. patent Nos. 7,741,402 (Bobsein et al) and 8,779,055 (Rabasco et al).

Once the make coat precursor is applied to the backing, and prior to curing, the abrasive particles are partially embedded in the make coat precursor. The cure of the make coat precursor then secures the abrasive particles in the make coat.

Useful abrasive particles can be the result of a crushing operation (e.g., crushed abrasive particles that have been classified according to shape and size) or a shaping operation (i.e., shaped abrasive particles) in which an abrasive precursor material is shaped (e.g., molded), dried, and converted to a ceramic material. Combinations of abrasive particles produced by comminution and abrasive particles produced by a forming operation may also be used. The abrasive particles can 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 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.

Suitable abrasive particles include, for example, crushed abrasive particles comprising: fused alumina, heat treated alumina, white fused alumina, ceramic alumina materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M company of santa paul, minnesota (3M Company,St.Paul,Minnesota), brown alumina, blue alumina, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, garnet, titanium carbide, diamond, cubic boron nitride, garnet, fused alumina-zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, silicon carbide, sol-gel prepared ceramics (e.g., alpha alumina), and combinations thereof. Examples of sol-gel processes from which abrasive particles can be isolated and methods of making the same can be found in U.S. patent 4,314,827 (leigheiser et al); 4,623,364 (Cottringer et al), 4,744,802 (Schwabel), 4,770,671 (Monroe et al) and 4,881,951 (Monroe et al). It is also contemplated that the abrasive particles may include abrasive agglomerates, such as those described, for example, in U.S. Pat. No. 4,652,275 (Bloecher et al) or 4,799,939 (Bloecher et al). In some embodiments, the abrasive particles may be surface treated or otherwise physically treated (e.g., iron oxide or titanium oxide) with a coupling agent (e.g., an organosilane coupling agent) to enhance the adhesion of the crushed abrasive particles to the binder. The abrasive particles may be treated prior to their incorporation into the binder, or they may be surface treated in situ by including a coupling agent into the binder.

Preferably, the abrasive particles (and in particular abrasive particles) comprise ceramic abrasive particles, such as, for example, polycrystalline alpha alumina particles prepared by a sol-gel process. Ceramic abrasive particles composed of crystallites of alpha alumina, magnesia alumina spinel, and rare earth hexaaluminates can be prepared using sol-gel alpha alumina particle precursors according to methods described in, for example, U.S. patent No. 5,213,591 (Celikkaya et al) and U.S. published patent application nos. 2009/0165394A1 (Culler et al) and 2009/0169816A1 (Erickson et al). Further details regarding methods of preparing sol-gel derived abrasive particles can be found, for example, in U.S. Pat. No. 4,314,827 (Leitheiser), U.S. Pat. No. 5,152,917 (Pieper et Al), U.S. Pat. No. 5,435,816 (Spurgeon et Al), U.S. Pat. No. 5,672,097 (Hoopman et Al), U.S. Pat. No. 5,946,991 (Hoopman et Al), U.S. Pat. No. 5,975,987 (Hoopman et Al) and U.S. published patent application No. 6,129,540 (Hoopman et Al), and U.S. published patent application No. 2009/0165394Al (Curer et Al).

In some preferred embodiments, useful abrasive particles (particularly in the case of abrasive particles) can be shaped abrasive particles, which can be found in U.S. Pat. nos. 5,201,916 (Berg), 5,366,523 (rowunhorst (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 formed into a specific shape, which are then crushed to form fragments that retain a portion of their original shape characteristics. In some embodiments, the abrasive particles are precisely shaped (i.e., the shape of the particles is determined at least in part by the shape of the cavities in the production tool used to prepare them). Details about such abrasive particles and methods of making them 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), U.S. patent application publication nos. 2012/0227333 (Adefris et al), 2013/0040537 (Schwabel et al) and 2013/0125777 (Adefris). One particularly useful precisely-shaped abrasive particle shape is a sheet shape having three side walls, any of which may be straight or concave and may be vertical or inclined relative to the sheet base; for example, as described in the references cited above. Fig. 2 illustrates an exemplary such precisely-shaped abrasive particle 200.

The surface coating on the abrasive particles may be used to improve adhesion between the abrasive particles and the binder material, or to aid in electrostatic deposition of the abrasive particles. In one embodiment, the surface coating described in U.S. Pat. No. 5,352,254 (Celikkaya) can be used in an amount of 0.1% to 2% of the surface coating relative to the weight of the abrasive particles. Such surface coatings are described in U.S. Pat. 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). In addition, the surface coating may prevent the shaped abrasive particles from being capped. "capping" is a term describing the phenomenon in which metal particles from a workpiece being abraded are welded to the tops of abrasive particles. Surface coatings that perform the above functions are known to those skilled in the art.

In some embodiments, 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 0.05mm to 3.0mm, and more typically in the range of 0.1mm to 2.6mm, although other lengths and widths may be used.

Abrasive particles having a thickness in the range of 0.1 microns to 1.6 mm, more typically 1 micron to 1.2 mm, may be selected, although other thicknesses may be used. In some embodiments, the abrasive particles can have an aspect ratio (length to thickness ratio) of at least 2, 3, 4, 5, 6, or more.

Abrasive particles can be individually sized according to an abrasive industry accepted prescribed nominal grade. Exemplary abrasive industry accepted grading standards include those promulgated by ANSI (american national standards institute), FEPA (european union of abrasive manufacturers), 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 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, JIS 6000, JIS 8000 and JIS 10,000. More typically, the size of the crushed alumina particles and the seeded sol-gel process prepared alumina-based abrasive particles are independently set to ANSI 60 and 80 or FEPA F36, F46, F54 and F60 or FEPA P60 and P80 classification standards.

Alternatively, the abrasive particles may be formulated using a test sieve conforming to the U.S. standard according to ASTM E-11"Standard Specification for Wire Cloth and Sieves for Testing Purposes (standard specification for sieve cloths and sieves for testing purposes). ASTM E-11 specifies the design and construction requirements of test sieves that use the media of a steel wire mesh woven screen cloth mounted in a frame to classify materials according to specified particle size. By 18+20 is meant that the shaped abrasive particles pass through a test sieve No. 18 conforming to ASTM E-11 specifications, but remain on a test sieve No. 20 conforming to ASTM E-11 specifications. In one embodiment, the shaped abrasive particles have a particle size such that: so that most of the particles pass through an 18 mesh test screen and can remain on a 20, 25, 30, 35, 40, 45 or 50 mesh test screen. In various embodiments, 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, -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.

Size layers are typically formed by coating and at least partially curing a size layer precursor comprising a thermosetting/curable composition over an at least partially cured make layer and abrasive particles, and at least partially curing the size layer precursor. Suitable size layer precursors/sizes layers may have the same or different compositions as those described above for inclusion in the primer layer precursors/sizes layers.

In some embodiments, the size layer precursor comprises a resole phenolic resin and an organic polymer rheology modifier, as described above in the context of the size layer precursor/size layer.

The make coat precursor comprises a water-based epoxy resin and an organic polymer rheology modifier as described above.

Exemplary water-based epoxy resins and their precursors (e.g., water-dispersible epoxy resins) include: epoxy resins sold by Van corporation of Columbus, ohio, such as EPI-Rez Resin WD-510 water dispersible liquid resins, and EPI-REZ resins 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, EPI-REZ Resin 3546-WH-53, EPI-REZ Resin 5520-W-60, EPI-REZ Resin 5522-WY-55, EPI-REZ Resin 5003-W-55, EPI-REZ Resin 2801-RSI-W-68 and EPI-REZ Resin 6006-2806-R < CHEM >; epoxy resins sold under the trade names d.e.r.900, d.e.r.913, d.e.r.915, d.e.r.916 and d.e.r.917 by olympin corporation of Clayton, missouri; and an epoxy resin from the company Allnex Corp, frankfurt, germany under the trade name BECKOPOX VEP 2381W/55 WA. Some preferred water-based epoxy resins include diglycidyl ethers of bisphenol a.

In some embodiments, the top coat is formed from a composition comprising a water-based epoxy resin, a nonionic emulsifier, water, an imidazole curative, a potassium tetrafluoroborate grinding aid, and a dispersant. Once the epoxy dispersion is applied to the coated abrasive product, it can be heated to cause polymerization of the epoxy resin. The heating is typically carried out at a temperature of about 80 ℃ to about 130 ℃, preferably about 105 ℃ to about 115 ℃ for a period of about 10 minutes to about 250 minutes, preferably about 20 minutes to about 50 minutes. Further details regarding water-based epoxy resins and topcoats containing them can be found, for example, in U.S. Pat. No. 5,556,437 (Lee et al).

Typically, the make coat also contains at least one grinding aid, although this is not required.

Grinding aid is a material that significantly affects the chemical and physical processes of grinding, resulting in improved performance. Grinding aids encompass a variety of different materials and may be inorganic or organic based. Examples of chemical groups of grinding aids include waxes, organic halide compounds, halide salts, metals and alloys thereof, and stearates and metal salts of stearates. The organic halide compound will typically decompose during milling and release the haloacid or gaseous halide. 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.

Other miscellaneous grinding aids include sulfur, organosulfur compounds, graphite, and metal sulfides. Combinations of different grinding aids may be used and in some cases this may result in synergistic enhancement.

Grinding aids are particularly useful in coated abrasives. In coated abrasive articles, a grinding aid is typically used in a make coat applied over the surface of the make coat. However, grinding aids are sometimes added to the size layer. Typically, the amount of grinding aid incorporated into the coated abrasive article is from about 50 to 800 grams per square meter (g/m) ² ) Preferably about 80g/m ² To 475g/m ² However, this is not necessarily so.

The top ply typically, but not necessarily, has a basis weight of 5 grams per square meter to 1100 grams per square meter (gsm), preferably 50gsm to 700gsm, and more preferably 250gsm to 600 gsm. The basis weight of the make, size, and optional make layers generally depends at least in part on the grit size grade and the particular type of abrasive article.

The make, size and top coats are formed by at least partially curing the corresponding precursors (i.e., the make, size and top coat precursors).

The make, size and top coats 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, etc.), coupling agents (e.g., silanes, titanates and/or zircoaluminates, etc.), plasticizers, suspending agents, and the like. The amounts of these optional additives are selected to provide the preferred characteristics. The coupling agent may improve adhesion to the abrasive particles and/or filler. The curable composition may be thermally curable, radiation curable, or a combination thereof.

The make, size and top coats and their precursors may also contain filler material, dilute abrasive particles (e.g., as described below), or grinding aid, typically in the form of particulate material. Typically, the particulate material is an inorganic material. Examples of fillers useful in the present disclosure include: metal carbonates (e.g., calcium carbonate (e.g., chalk, calcite, clay, lime, 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, clay, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminate, sodium silicate) metal sulfates (e.g., calcium sulfate, barium 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).

Further details regarding coated abrasive articles and methods of their manufacture can be found, for example, in U.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 (benenect et al), 5,520,711 (Helmin), 5,961,674 (gagiardi et al), and 5,975,988 (Christianson).

Coated abrasive articles according to the present disclosure may be used, for example, to abrade a workpiece. Such methods may include: abrasive particles according to the present disclosure are brought into frictional contact with a workpiece surface, and at least one of the coated abrasive particles and the workpiece surface is moved relative to the other to abrade at least a portion of the workpiece surface. Methods of abrading with coated abrasive articles according to the present disclosure include, for example, barren (i.e., high pressure high cutting) to finish (e.g., polishing medical implants with coated abrasive belts), where the latter are typically accomplished with finer grades (e.g., ANSI 220 and finer grades) of abrasive particles. The size of the abrasive particles for a particular abrading application will be apparent to those skilled in the art.

Grinding may be performed dry or wet. For wet milling, the liquid introduced may be provided in the form of a mist to a complete stream of water. Examples of common liquids include water, water-soluble oils, organic lubricants, and emulsions. These liquids may be used to reduce heat associated with grinding and/or as lubricants. The liquid may contain minor amounts of additives such as bactericides, defoamers and the like.

Examples of workpieces include aluminum metal, carbon steel, low carbon steel (e.g., 1018 low carbon steel and 1045 low carbon steel), tool steel, stainless steel, hardened steel, titanium, glass, ceramic, wood-based materials (e.g., plywood and particle board), paint, painted surfaces, organic-coated surfaces, and the like. The force applied during grinding is typically in the range of about 1 to about 100 kilograms (kg), although other pressures may be used.

Selected embodiments of the present disclosure

In a first embodiment, the present disclosure provides a method of making a coated abrasive article comprising:

and

In a second embodiment, the present disclosure provides the method of the first embodiment, wherein the at least partially curing the make layer precursor is performed in a pendant oven.

In a third embodiment, the present disclosure provides the method of the first or second embodiment, wherein the make layer precursor has a basis weight of 5 grams to 1100 grams per square meter.

In a fourth embodiment, the present disclosure provides the method of any one 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 ethoxylated polyurethane polymers, and combinations thereof.

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

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

In a seventh embodiment, the present disclosure provides the method of the sixth embodiment, wherein the shaped abrasive particles comprise precisely-shaped abrasive particles.

In an eighth embodiment, the present disclosure provides the method of the sixth embodiment, wherein the shaped abrasive particles comprise precisely-shaped triangular flakes.

In a ninth embodiment, the present disclosure provides a coated abrasive article comprising:

a backing having opposed first and second major surfaces;

a top adhesive layer arranged on the compound adhesive layer,

In a tenth embodiment, 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 ethoxylated polyurethane polymers, and combinations thereof.

In an eleventh embodiment, the present disclosure provides a coated abrasive article according to the ninth or tenth embodiment, wherein the amount of the at least partially epoxy resin comprises 85 wt% to 99.99 wt% of the total weight of the at least partially cured epoxy resin and the organic polymer rheology modifier.

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

In a thirteenth embodiment, the present disclosure provides a coated abrasive article according to the twelfth embodiment, wherein the shaped abrasive particles comprise precisely-shaped abrasive particles.

In a fourteenth embodiment, the present disclosure provides a coated abrasive article according to the twelfth embodiment, wherein the shaped abrasive particles comprise precisely-shaped triangular flakes.

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

Examples

All parts, percentages, ratios, etc. in the examples and the remainder of the specification are by weight unless otherwise specified. Table 1 below reports the materials used in the examples.

TABLE 1

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Preparation of the resin

Comparison of top gum layer precursorsCSSR-A

A3 liter plastic container was charged with 438 grams ER, 173 grams water, 8.7 grams ADD4, 55.1 grams ADD 5, 13.8 grams ADD 6, 18.1 grams SF1, 1.9 grams SF2, and 319.4 grams LR, and then mixed with an overhead mechanical stirrer for 10 minutes. Then 1972 g FIL2 were added over a period of 15 minutes. The resulting mixture was stirred with an overhead stirrer for 15 minutes.

Comparison of top gum layer precursorsCSSR-B、CSSR-C、CSSR-DAndCSSR-E

a118 ml glass jar was charged with 99.5 grams CSSR-A and 0.25 grams FIL1. The mixture was stirred with an overhead stirrer for 5 minutes to prepare comparative top gum layer precursor CSSR-B. Comparative top coat precursors CSSR-C, CSSR-D and CSSR-E were prepared in a similar manner and the formulations are described in Table 2.

Top coat precursorESSR-1AndESSR-2

to a 118ml glass vessel was added 99.5 grams CSSR-A and 0.5 grams ADD 2. The mixture was stirred with an overhead stirrer for 5 minutes to prepare a top gum layer precursor 1 (ESSR-1). Exemplary top coat precursor 2 (ESSR-2) was prepared in a similar manner and the formulation is described in Table 2.

Top coat precursorESSR-3AndESSR-4

to a 118ml glass jar was added 99.5 grams CSSR-A and 0.5 grams ADD. The mixture was stirred with an overhead stirrer for 5 minutes to prepare a top gum layer precursor ESSR-3. The top coat precursor ESSR-4 examples were prepared in a similar manner and the formulations are described in Table 2 below.

TABLE 2

Inclined plane flow test

The inclined plane flow test involves placing a drop of 0.1 gram of resin at a specified temperature on a horizontally placed slide, and then rapidly tilting the slide on an inclined device set at an angle of 48.7 deg. for 1 minute (see figures 1, 2 and tables 2, 3). The distance traveled by the resin in millimeters (mm) was recorded in minutes. The smaller the distance, the less likely the resin will flow excessively and cause bottom loop tack in the pendant curing oven (bottom loop puddling). Analysis of the data (FIGS. 1, 2 and Table 2, 3) clearly illustrates the thixotropic properties of ESSR-1, 2, 3 and 4. In fact, these examples show a 10-to 20-fold improvement over the comparative examples (CSSR-A, B, C and D) on a 100% solids basis.

Table 3 below shows the results of inclined plane flow tests of various resins at Room Temperature (RT) and 41 ℃.

TABLE 3 Table 3

Primer resin MR

A 17 liter bucket was charged with 7812 grams PF, 6823 grams FIL1, and 364 grams water to prepare a primer resin. The resin was mixed with an overhead stirrer at room temperature for 30 minutes.

Adhesive resinSR1

To a 17 liter bucket were added 11100 g PF, 5800 g FIL1, 420 g ADD5, and 2000 g water to prepare a size resin. The resin was mixed with an overhead stirrer at room temperature for 30 minutes.

Adhesive resinSR2

To a 17 liter bucket were added 11100 grams of PF, 5800 grams of FIL1, 420 grams of ADD5, 118 grams of ADD3, and 2000 grams of water to prepare a size resin. The resin was mixed with an overhead stirrer at room temperature for 30 minutes.

Top coat precursorESSR-5

An exemplary topstock precursor ESSR-5 was prepared by: into a 17 liter bucket were charged 18180 grams of CSSR-A, 92 grams of ADD2, 92 grams of ADD3, and 614 grams of water, and mixed with an overhead mechanical stirrer for 30 minutes.

Coated abrasive comparative top glueCSSR-F

Coated abrasive examples and comparative examples were prepared by: the primer resin MR was roll coated onto a 30.48cm wide continuous polyester backing (as described in example 12 of U.S. patent No. 6,843,815 by thunber et al) at a coating weight of 210 grams per square meter (gsm), followed by electrostatic coating of mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90 ℃ for 90 minutes and at 102 ℃ for 60 minutes. The resulting material was then roll coated with a size coat resin SR1 at a coating weight of 567 grams per square meter (gsm). The material was cured at 90 ℃ for 60 minutes and at 102 ℃ for 60 minutes. The resulting material was then roll coated with comparative top size layer precursor CSSR-a at a coating weight of 567 grams per square meter (gsm). Finally the material was cured at 90 ℃ for 60 minutes, at 102 ℃ for 12 hours and at 109 ℃ for 1 hour.

Coated abrasive embodiment top dressingESSR-5

Coated abrasive examples and comparative examples were prepared by: the primer resin MR was roll coated onto a 30.48cm wide continuous polyester backing (as described in example 12 of U.S. patent No. 6,843,815 by thunber et al) at a coating weight of 210 grams per square meter (gsm), followed by electrostatic coating of mineral SAP1 at a weight of 605 gsm. The coated material was cured at 90 ℃ for 90 minutes and at 102 ℃ for 60 minutes. The resulting material was then roll coated with size resin SR2 at a coating weight of 567 grams per square meter (gsm). The material was cured at 90 ℃ for 60 minutes and at 102 ℃ for 60 minutes. The resulting material was then roll coated with comparative top coat precursor ESSR-5 at a coating weight of 567 grams per square meter (gsm). Finally the material was cured at 90 ℃ for 60 minutes, at 102 ℃ for 12 hours and at 109 ℃ for 1 hour.

Comparison of coated abrasive top bond line precursors

As shown in fig. 3 and 4, the coated abrasive article prepared using the comparative make layer precursor CSSR-F (shown in fig. 3) exhibited a bottom loop blocking problem, whereas the same coated abrasive article except for the use of the make layer precursor ESSR-5 (shown in fig. 4) did not.

All cited references, patents and patent applications incorporated by reference in this application are incorporated by reference in a consistent manner. In the event of an inconsistency or contradiction between the incorporated reference sections and the present application, the information in the present application shall prevail. The previous description of the disclosure, provided to enable one of ordinary skill in the art to practice the disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the appended claims and all equivalents thereof.

Claims

1. A method of making a coated abrasive article, the method comprising:

providing a backing having opposed first and second 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, further wherein a size layer is disposed on at least a portion of the make layer and the abrasive particles; and

wherein the make coat precursor comprises a water-based epoxy resin and an organic polymer rheology modifier, wherein the organic polymer rheology modifier comprises an alkali-swellable/soluble polymer, and wherein the amount of the water-based epoxy resin is from 75 wt% to 99.99 wt% of the total weight of the water-based epoxy resin and the organic polymer rheology modifier on a solids basis.

2. The method of claim 1, wherein the at least partially curing the top coat precursor is performed in a pendant oven.

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

4. The method of claim 1, wherein the organic polymeric rheology modifier is selected from the group consisting of alkali swellable/soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof.

5. The method of claim 1, wherein the amount of the water-based epoxy resin is 85 to 99.99 weight percent based on solids based on the total weight of the water-based epoxy resin and the organic polymer rheology modifier.

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

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

8. The method of claim 6, wherein the shaped abrasive particles comprise precisely-shaped triangular flakes.

9. A coated abrasive article comprising:

a backing having opposed first and second major surfaces;

a top adhesive layer arranged on the compound adhesive layer,

wherein the top coat comprises an at least partially cured epoxy resin and an organic polymer 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 polymer rheology modifier.

10. The coated abrasive article of claim 9 wherein the organic polymeric rheology modifier is selected from the group consisting of alkali swellable/soluble acrylic polymers, hydrophobically modified ethoxylated polyurethane polymers, and combinations thereof.

11. The coated abrasive article of claim 9, wherein the amount of the at least partially epoxy resin comprises 85 wt% to 99.99 wt% of the total weight of the at least partially cured epoxy resin and the organic polymeric rheology modifier.

12. The coated abrasive article of claim 9, wherein the abrasive particles comprise shaped abrasive particles.

13. The coated abrasive article of claim 12 wherein the shaped abrasive particles comprise precisely-shaped abrasive particles.

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