Antiloading components for abrasive articles

An abrasive article, for example, a coated, bonded, or nonwoven abrasive article comprising a binder, a plurality of abrasive particles, and an antiloading component in a peripheral coating of the abrasive article.

 

What is claimed is:

1. An abrasive article comprising

(a) a backing having a major surface;

(b) a plurality of abrasive particles;

(c) a binder which adheres the plurality of abrasive particles to the major surface of the backing; and

(d) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof ##STR5## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and ##STR6## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively.

2. An abrasive article comprising

(a) a backing having a major surface;

(b) a plurality of abrasive particles;

(c) a make coat which adheres the plurality of abrasive particles to the major surface of the backing;

(d) a size coat overlaying the make coat and the plurality of abrasive particles; and

(e) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof: ##STR7## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and ##STR8## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively.

3. The abrasive article of claim 1 wherein the binder and the plurality of abrasive particles are present in an abrasive coating.

4. The abrasive article of claim 1 wherein the binder and the plurality of abrasive particles are present in a plurality of abrasive composites.

5. The abrasive article in accordance with claim 1 wherein the antiloading component is selected from the group consisting of octadecyl phosphate, docosyl phosphate, tetradecyl phosphonic acid, hexadecyl phosphate, octadecyl phosphonic acid, hexadecyl phosphonic acid, octadecylammonium phosphate, octadecylammonium phosphite, hexadecyl ammonium phosphate, hexadecylammonium phosphite, docosylammonium phosphate, docosylammonium phosphite, octadecyldimethylammonium phosphate, and octadecyldimethylammonium phosphite.

6. The abrasive article in accordance with claim 1 wherein the antiloading component is present in the peripheral coating in an amount ranging from 95 to 100% by weight, based on a total weight of the peripheral coating.

7. A bonded abrasive comprising

(a) a plurality of abrasive particles;

(b) a binder adhering the plurality of abrasive particles together; and

(c) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof: ##STR9## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a, where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and ##STR10## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a, where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively.

8. A nonwoven abrasive comprising

(a) an open, lofty nonwoven substrate;

(b) a plurality of abrasive particles;

(c) a binder adhering the plurality of abrasive particles into and/or onto the open, lofty nonwoven substrate; and

(d) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof: ##STR11## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a, where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and ##STR12## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively.

9. A method of making an abrasive article comprising:

(a) providing a backing having at least one major surface;

(b) applying a make coat binder precursor over the at least one major surface of the backing;

(c) embedding a plurality of abrasive particles into and/or onto the make coat binder precursor;

(d) at least partially curing the make coat binder precursor to form a make coat;

(e) applying a size coat binder precursor to form a size coat;

(f) curing the size coat binder precursor;

(g) applying a peripheral composition over at least a portion of the size coat, said composition comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof: ##STR13## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and ##STR14## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; and

(h) drying the composition to form a peripheral coating.

10. The method in accordance with claim 9 wherein the antiloading component is present in the peripheral composition in an amount ranging from 1 to 100% by weight, based on the total weight percent of the peripheral composition.

11. The method in accordance with claim 9 wherein the antiloading component is selected from the group consisting of octadecyl phosphate, docosyl phosphate, tetradecyl phosphonic acid, hexadecyl phosphate, octadecyl phosphonic acid, hexadecyl phosphonic acid, octadecylammonium phosphate, octadecylammonium phosphite, hexadecyl ammonium phosphate, hexadecylammonium phosphite, docosylammonium phosphate, docosylammonium phosphite, octadecyldimethylammonium phosphate, and octadecyldimethylammonium phosphite.

12. The method in accordance with claim 9 wherein the peripheral coating further comprises a liquid medium.

13. The method in accordance with claim 12 wherein the liquid medium is an organic solvent or water.

14. The method in accordance with claim 12 wherein the antiloading component is present as a dispersion in the liquid medium.

15. The method in accordance with claim 12 wherein the antiloading component is in solution.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an abrasive article comprising a binder, abrasive grains, and peripheral coating comprising an antiloading component.

2. Discussion of Related Art

There are numerous types of abrasive articles. For example, an abrasive article generally comprises abrasive particles bonded together as a bonded abrasive article, bonded to a backing as a coated abrasive article, or bonded into and/or onto a three-dimensional nonwoven substrate as a nonwoven abrasive article. Each type of abrasive article may also be in a variety of forms. For example, a coated abrasive article can comprise a first layer (also known as a make coat), a plurality of abrasive particles adhered thereto and therein, and a second layer (also known as a size coat). In some instances, a third layer (also known as a supersize coat) may be applied over the size coat. Alternatively, a coated abrasive article may be a lapping coated abrasive comprising an abrasive coating (which also can be referred to as an "abrasive layer") bonded to a backing where the abrasive coating comprises a plurality of abrasive particles dispersed in a binder. In addition, a coated abrasive article may be a structured abrasive comprising a plurality of precisely shaped abrasive composites bonded to a backing. In this instance, the abrasive composites comprise a plurality of abrasive particles.

Abrasives articles are used to abrade a wide variety of substrates or workpieces made from, for example, wood, plastic, fiberglass, or soft metal alloys, or having a layer of enamel or paint. Typically, there is some degree of space between these abrasive particles. During the abrading process, material abraded from the substrate or workpiece, also known as swarf, tends to fill the spaces between abrasive particles. The filling of spaces between abrasive particles with swarf and the subsequent build-up of swarf is known as loading. Loading presents a concern because the life of the abrasive article is reduced and the cut rate of the abrasive article decreases (thus, more force may be required to abrade). In addition, loading is an exponential problem; once swarf begins to fill in the spaces between abrasive particles, the initial swarf acts as a "seed" or "nucleus" for additional loading.

The abrasive industry has sought loading-resistant materials to use in abrasive articles. Examples of loading-resistant materials which have been used include metal salts of fatty acids, urea-formaldehyde resins, waxes, mineral oils, crosslinked silanes, crosslinked silicones, and fluorochemicals. Preferred materials have been zinc stearate and calcium stearate. One theory for the success of metal stearates as an antiloading agent is that the metal stearate coating powders off the coated abrasive surface during the abrading process, which in turn causes the swarf to also powder off of the surface, thus reducing the amount of loading.

Stearate coatings for the prevention of loading have been utilized by the abrasives industry for several decades. It has been common to utilize a binder with the stearate to assist in applying and retaining the coating on the abrasive surface. Some minor improvements over the years have been made by utilizing stearates with higher melting points, for example, calcium or lithium stearate and by incorporating additives to enhance antiloading performance, for example, fluorochemicals.

Specific attempts to solve the problem of loading include those taught in U.S. Pat. Nos. 2,768,886 (Twombly); 2,893,854 (Rinker et al.); and 3,619,150 (Rinker et al.). U.S. Pat. No. 2,768,886 discloses an abrasive article with a coating of small, solid particles consisting essentially of stearates or palmitates. U.S. Pat. No. 2,893,854 discloses a coated abrasive article coated with a continuous film of a resin having uniformly dispersed small, solid particles of a water-insoluble metallic soap of a saturated fatty acid having from 16 to 18 carbon atoms. U.S. Pat. No. 3,619,150 discloses a coated abrasive article having a nonloading coating comprising a mixed resin composition of a thermosetting resin and either a thermoplastic or elastomeric resin and a water-dispersible metallic soap, in particular, a metallic water-insoluble soap of a C16 to C18 saturated fatty acid, dispersed throughout the resin composition.

U.S. Pat. No. 4,609,380 (Barnett) discloses an abrasive wheel having a binder system comprising a binder and a smear-reducing compatible polymer and conventional lubricants including metal stearate salts such as lithium stearate.

U.S. Pat. No. 4,784,671 (Elbel) discloses a process for improving the grinding performance of a porous ceramic or plastic bound grinding or honing body comprising filling the pore spaces at least in part with at least one metal soap, including salts and soaps of the fatty acids of lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid. A grinding performance improvement disclosed is reduction of clogged pores of the body to avoid rewelding and sheet metal jacket formations.

U.S. Pat. No. 4,988,554 (Peterson et al.) discloses a coated abrasive article having a backing having a layer of abrasive grains overcoated with a loading resistant coating comprising a lithium salt of a fatty acid on one side and a pressure-sensitive adhesive on the other side of the backing.

U.S. Pat. No. 4,396,403 (Ibrahim) discloses a coated abrasive article, which does not need a supersize coat of metal stearates or any other material, which instead incorporates phosphoric acids, partial esters of such acids, amine salts of such acids and partial esters, and/or quaternary ammonium salts with at least one long substituent group into amino resin or glue sizing adhesives during the manufacture of the coated abrasive article.

U.S. Pat. No. 4,973,338 (Gaeta et al.) discloses a coated abrasive that has been oversized with an antiloading amount of a quaternary ammonium anti-static compound comprising from about 15 to 35 carbon atoms and having a molecular weight not less than about 300. Examples of the quaternary ammonium compounds include (3-lauramido-propyl)trimethylammonium methyl sulfate, stearamidopropyldimethyl-beta-hydroxyethylammoniumnitrate, N,N-bis(2-hydroxyethyl)-N-(3"-dodecyloxy-2"-hydroxypropyl)methylammonium methosulfate and stearamidopropyl-dimethyl-beta-hydroxyethyl-ammoniumdihydrogen phosphate. Typically, the quaternary ammonium compound is coated out of a solvent, typically an aqueous alcohol solvent system.

U.S. Pat. No. 5,164,265 (Stubbs) discloses an abrasive article having, either applied as a layer coated over existing layers of an abrasive article or incorporated into the coating formulation which will form the outermost layer of the binder, a fluorochemical compound selected from the group consisting of compounds comprising a fluorinated aliphatic group attached to a polar group or moiety and compounds having a molecular weight of at least about 750 and comprising a non-fluorinated polymeric backbone having a plurality of pendant fluorinated aliphatic groups comprising the higher of (a) a minimum of three C--F bonds, or (b) in which 25% of the C--H bonds have been replaced by C--F bonds such that the fluorochemical compounds comprises at least 15% by weight of fluorine.

Although the abrasive industry has widely used metal stearates with a good degree of success, the industry is always looking for improved antiloading components, particularly to lengthen product life. Although there have been a number of improvements recently for backings, bond systems, and minerals of coated abrasives, comparable improvements in antiloading components have not yet been achieved. That is, the industry is still seeking a component which is easy to apply, is relatively inexpensive, and can be utilized during abrading of a variety of workpieces including paint, wood, wood sealers, plastic, fiberglass, composite material, and automotive body fillers and putties.

SUMMARY OF THE INVENTION

In the present invention, an antiloading component for an abrasive article has been developed which meets the needs of the industry, i.e., the present invention relates to an abrasive article construction containing an antiloading component which significantly minimizes loading, is coatable, and is relatively inexpensive.

The present invention relates to an abrasive article comprising (a) a backing having a major surface; (b) a plurality of abrasive particles; (c) a binder which adheres the plurality of abrasive particles to the major surface of the backing; and (d) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof.

The present invention also relates to an abrasive article comprising (a) a backing having a major surface; (b) a plurality of abrasive particles; (c) a make coat which adheres the plurality of abrasive particles to the major surface of the backing; (d) a size coat overlaying the make coat and the plurality of abrasive particles; and (e) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof.

In another embodiment, the present invention relates to a bonded abrasive comprising (a) a plurality of abrasive particles; (b) a binder adhering the plurality of abrasive particles together; and (c) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof.

In yet another embodiment, the present invention relates to a nonwoven abrasive comprising (a) an open, lofty nonwoven substrate; (b) a plurality of abrasive particles; (c) a binder adhering the plurality of abrasive particles into and/or onto the open, lofty nonwoven substrate; and (d) a peripheral coating comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof.

The present invention also relates to a method of making an abrasive article comprising (a) providing a backing having at least one major surface; (b) applying a make coat binder precursor over the at least one major surface of the backing; (c) embedding a plurality of abrasive particles into and/or onto the make coat binder precursor; (d) at least partially curing the make coat binder precursor to form a make coat; (e) applying a size coat binder precursor over the make coat and the plurality of abrasive particles; (f) curing the size coat binder precursor to form a size coat; (g) applying a peripheral composition over at least a portion of the size coat, said composition comprising an antiloading component of any of formulas 1 and 2 or mixtures thereof; and (h) drying the composition to form a peripheral coating.

The antiloading component can be any of formulas 1 and 2 or mixtures thereof: ##STR1## wherein R.sup.1 and R.sup.2 are independently OH or OR,

R is an alkyl group;

X is O, S, NH, or a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group;

p is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively; ##STR2## wherein R.sup.3 and R.sup.4 independently are H or an alkyl group;

Z.sup.- is a monovalent anion;

A is a divalent aliphatic or aromatic linking group having 20 atoms or less and containing carbon and, optionally, nitrogen, oxygen, phosphorus, and/or sulfur in the aliphatic or aromatic group or as a substituent to the aliphatic or aromatic group, with the proviso that the linking group is connected by a carbon atom to N of formula 2;

t is 0 or 1; and

W is an alkyl group, or W is a fluorinated hydrocarbon having a formula C.sub.m H.sub.a F.sub.2m+1-a where a is 0 to 2m and m is 4 to 50, wherein the alkyl group or the fluorinated hydrocarbon may contain oxygen atoms in a backbone of the alkyl group or the fluorinated hydrocarbon, respectively, in an amount ranging from 1 to 1/2 a total number of carbon atoms present in the alkyl group or the hydrocarbon, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of an embodiment of a coated abrasive article in accordance with the present invention.

FIG. 2 is a cross-section of an embodiment of a structured abrasive article in accordance with the present invention.

FIG. 3 is a partial expanded view of a nonwoven abrasive article in accordance with the present invention.

FIG. 4 is a cross-section taken along line 6--6 of FIG. 3.

FIG. 5 is a reduced plan view of a portion of a concatenate of abrasive discs in accordance with the present invention.

FIG. 6 is a greatly reduced perspective view of a roll of coated abrasive material in accordance with the present invention.

FIG. 7 is a cross-section of another embodiment of a coated abrasive article in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Abrasive articles and methods of making and using abrasive articles in accordance with the present invention will be discussed in more detail below.

Abrasive Articles

Abrasive articles typically comprise a plurality of abrasive particles adhered by a bond system comprising a binder which can be derived from a binder precursor. Examples of abrasive articles include coated abrasive articles such as lapping or structured abrasive articles, bonded abrasive articles, and nonwoven abrasive articles.

Abrasive articles generally comprise abrasive particles secured within a binder. In a bonded abrasive, the binder bonds the abrasive particles together in a shaped mass. Typically, this shaped mass is in the form of a wheel and thus it is commonly referred to as a grinding wheel. In nonwoven abrasives, the binder bonds the abrasive particles into and/or onto a lofty, open, fibrous substrate. In coated abrasives, the binder bonds the abrasive particles to a substrate or backing.

Abrasive articles of the present invention comprise an antiloading component in a peripheral coating of the abrasive article capable of contacting a workpiece. The term "peripheral coating" as used herein refers to the outermost coating of an abrasive article which contacts a workpiece to be abraded.

Coated Abrasive Articles

Coated abrasive articles of the invention may be produced with coatable binder precursor compositions, described herein, on a backing. As mentioned above, there are a variety of types of coated abrasive articles.

A backing for a coated abrasive article of the present invention can be any number of various materials conventionally used as backings in the manufacture of coated abrasives, such as paper, cloth, film, polymeric foam, vulcanized fibre, woven and nonwoven materials, and the like, or a combination of two or more of these materials or treated versions thereof. The choice of backing material will depend on the intended application of the abrasive article. The strength of the backing should be sufficient to resist tearing or other damage in use, and the thickness and smoothness of the backing should allow achievement of the product thickness and smoothness desired for the intended application.

The backing may also be a fibrous reinforced thermoplastic, for example, as disclosed in U.S. Pat. No. 5,417,726 (Stout), or an endless spliceless belt, for example, as disclosed in WO 93/12911 (Benedict et al.). Likewise, the backing may be a polymeric substrate having hooking stems projecting therefrom, for example, as disclosed in WO 95/19242 (Chesley et al.). Similarly, the backing may be a loop fabric, for example, as described in WO 95/11111 (Follett et al.).

The backing may be smooth, textured, or perforated and may have a thickness ranging generally from about 25 to about 10,000 micrometers, typically from 25 to 1000 micrometers.

The backing may comprise a polymeric film, cloth, paper sheet, treated versions thereof, a screen made from plastic or metal, and treated or untreated combinations thereof. In some applications it is also preferable that the backing be waterproof. The thickness of the backing should be sufficient to provide the strength desired for the intended application; nevertheless, it should not be so thick as to affect the desired flexibility in the coated abrasive product. The film backing may be made from a thermoplastic material such as polyamides (nylon), polyester, polypropylene, polyethylene, polyurethane, combinations thereof, and the like. The film backing may also be a microvoided film backing. As used herein "microvoided" means that the film has internal porosity. A particularly preferred film is a microvoided polyester (preferably polyethylene terephthalate) film having a thickness ranging from 0.01 mm to 0.25 mm, more preferably 0.05 mm. An example of a microvoided polyester film is one which is commercially available from ICI Limited, United Kingdom under the trade designation "475/200 MELINEX MV". The film backings may be primed or unprimed. The backing may also be a laminate of paper/film, two polymeric films, paper/cloth/film, film/nonwoven material, and the like.

With reference to FIG. 1, a coated abrasive article 10 of the present invention may include a first coating layer 12 (commonly referred to as a make coat) bonded to one side (a major surface) of a backing 11, at least one layer of abrasive particles 13 bonded to the backing 11 by the make coat 12, a second coating layer 16 (commonly referred to as a size coat) overlaying the abrasive particles, and a peripheral coating 14, comprising an antiloading component of the present invention, over at least a portion of the second coating layer 16.

Coated abrasives of the present invention also include lapping abrasive articles and structured coated abrasive articles. A lapping coated abrasive article comprises a backing having an abrasive coating bonded to the backing; the abrasive coating comprising a plurality of abrasive particles distributed in a binder. In some instances, the binder bonds this abrasive coating to the backing. Alternatively, an additional material may be used to bond the abrasive coating to the backing, which may be selected, for example, from the binder precursors described herein and may be the same or different than the binder precursor used to form the abrasive coating. Generally, the particle size of the abrasive particles used in a lapping coated abrasive ranges, on average, from about 0.1 to less than about 200 micrometers, typically, 0.1 to 120 micrometers. The abrasive coating may have a smooth outer surface or a textured outer surface. The abrasive coating may also further comprise additives as discussed herein.

With reference to FIG. 2, a structured abrasive article 20 comprises a backing 32 having a plurality of precisely shaped abrasive composites 31 bonded to a major surface 33 of the backing 32 and a peripheral coating 38, comprising an antiloading component of the present invention, over at least a portion of the plurality of abrasive composites 31. These abrasive composites comprise a plurality of abrasive particles 34 distributed in a binder 35. In some instances, the binder 35 bonds the abrasive composites to the backing. Alternatively, an additional material may be used to bond the abrasive composite to the backing, which may be selected, for example, from the binder precursors described herein and may be the same or different than the binder precursor used to form the abrasive composite.

Generally, the particle size range for abrasive particles used in a structured coated abrasive is the same as that used for a coated abrasive article comprising a make coat and size coat as described herein. The abrasive composites may also comprise additives that are discussed herein.

As described herein, each of the embodiments of a coated abrasive article contains a peripheral coating over at least a portion of the binder and abrasive particles of the abrasive article. For example, the peripheral coating may overlay a size coat, an abrasive coating, or abrasive composites This coating may be referred to as a "supersize coat" for coated abrasive articles having make and size coats.

In some instances, it may be preferred to incorporate a pressure sensitive adhesive onto the back side of the coated abrasive such that the resulting coated abrasive can be secured to a back up pad. Representative examples of pressure sensitive adhesives suitable for this invention include latex crepe, rosin, acrylic polymers and copolymers e.g., polybutylacrylate, polyacrylate ester, vinyl ethers, e.g., polyvinyl n-butyl ether, alkyd adhesives, rubber adhesives, e.g., natural rubber, synthetic rubber, chlorinated rubber, and mixtures thereof. A preferred pressure sensitive adhesive is an isooctylacrylate:acrylic acid copolymer.

Alternatively, the coated abrasive may contain a hook and loop type attachment system to secure the coated abrasive to the back up pad. The loop fabric may be on the back side of the coated abrasive with hooks on the back up pad. Alternatively, the hooks may be on the back side of the coated abrasive with the loops on the back up pad. With reference to FIG. 7, the coated abrasive 70 may include a first coating layer 12 bonded to a major surface of the backing 11, at least one layer of abrasive particles 13 bonded to the backing 11 by the first coating layer 12, and a second coating layer 16 overlaying the abrasive particles, a third coating layer 14 (also referred to as a peripheral coating), comprising an antiloading component of the present invention, over at least a portion of the second coating layer 16, and hooks 17 attached to the backing 11 on the back side, i.e., the side opposite to the major surface of the backing 11 bearing abrasive particles 13.

This hook and loop type attachment system is further described in U.S. Pat. Nos. 4,609,581 and 5,254,194, WO 95/19242 and U.S. Ser. Nos. 08/181,192; 08/181,193; and 08/181,195, all incorporated herein by reference. For example, a make coat precurosr may be coated directly onto a loop fabric, which may be a chenille stitched loop, a stitchbonded loop (for example, as dislcosed in U.S. Pat. No. 4,609,581 (Ott), incorporated herein by reference), or a brushed loop, for example, brushed nylon. The loop fabric may also contain a sealing coat to seal the loop fabric and prevent the make coat precursor from penetrating into the loop fabric. Alternatively, the make coat precursor may be coated directly onto the loop fabric, for example, as disclosed in WO 95/11111 (Follett et al.), incorporated herein by reference. In this arrangement, the loop fabric can releasably engage with hooking stems present on a support pad. The make coat precursor may also be coated directly on a hooking stem substrate, which generally comprises a substrate having a front and back surface. The make coat precursor can then be applied to the front surface of the substrate, the hooking stems protruding from the back surface. In this arrangement, the hooking stems can releasably engage with a loop fabric present on a support pad.

It is also within the scope of this invention to have a binder and plurality of abrasive particles adhered directly to a loop fabric and have the antiloading component present in a peripheral coating.

The coated abrasive can be in the form of a roll of abrasive discs, as described in U.S. Pat. No. 3,849,949 (Steinhauser et al.) incorporated herein by reference.

The coated abrasive may be converted into a variety of different shapes and forms such as belts, discs, sheets, tapes, daisies and the like. The belts may contain a splice or a joint, alternatively the belts may be spliceless such as that taught by in WO 93/12911 incorporated herein by reference. The belt width may range from about 0.5 cm to 250 cm, typically anywhere from about 1 cm to 150 cm. The belt length may range from about 5 cm to 1000 cm, typically 10 cm to 500 cm. The belt may have straight or scalloped edges. The discs may contain a center hole or have no center hole. The discs may have the following shapes: round, oval, octagon, pentagon, hexagon or the like; all of these converted forms are well known in the art. The discs may also contain dust holes, typically for use with a tool containing a vacuum source. The diameter of the disc may range from about 0.1 cm to 1500 cm, typically from 1 cm to 100 cm. The sheets may be square, triangular, or rectangular. The width ranges from about 0.01 cm to 100 cm, typically 0.1 cm to 50 cm. The length ranges from about 1 cm to 1000 cm, typically 10 cm to 100 cm.

For example, FIG. 5 shows a plan view (reduced) of an abrasive article of the invention, a concatenation 50 of edge-connected coated abrasive discs 72 capable of being convolutely wound to form a roll which can be easily unrolled. Alternately, other shapes of coated abrasive can be used. A concatenation of coated abrasive is more fully described in assignee's U.S. Pat. No. 3,849,949, incorporated herein by reference. Each disc 72 preferably has a structure as shown in cross-section, for example, in FIG. 1 and is joined to at least one other similarly constructed disc 72 along a straight edge 74 of the disc formed by removal of a small segment defined by a chord having a length less than 1/2 the radius of the disc. Straight edge 74 is preferably perforated for easy separation of the discs along the chord; however, perforation is not necessary. This concatenation 50 of coated abrasive discs, when wound into a roll, has a peripheral coating (for example, as shown in FIG. 1), containing an antiloading component of the present invention, of one disc 72 in direct, releasable contact with the PSA on the back side of another disc 72 when the concatenation is convolutely wound. The discs can be easily separated from one another when desired.

Alternatively, with reference to FIG. 6, which shows a reduced perspective view of another preferred article of the invention, a packaged roll 60 of coated abrasive employing an antiloading component of the present invention may be used. Roll 60 comprises an elongated sheet of coated abrasive material 82 of the type shown in cross-section in, for example, FIG. 1. The materials of construction suitable for roll 60 can be the same as those used in aforementioned coated abrasive article 10. In FIG. 6, it can be seen that when the coated abrasive material is wound into a roll, a peripheral coating 81 comprising an antiloading component of the present invention will be in direct, releasable contact with a layer of PSA 83. When the user desires to remove a piece of coated abrasive material from roll 60, the user merely unwinds a portion of roll 60 and cuts or tears this portion from the roll.

When a PSA is used, if necessary to prevent transfer of the antiloading component to the PSA or vice versa, a release liner may be used, the roll may be wound loosely, or a binder (in amounts as described herein) may be incorporated along with the antiloading component.

It is also feasible to adhere the abrasive particles to both a major or working surface and the opposite surface of a backing. The abrasive particles can be the same or different from one another. In this aspect, the abrasive article is essentially two sided; one side can contain a plurality of abrasive particles which are different from a plurality of abrasive particles on the other side. Alternatively, one side can contain a plurality of abrasive particles having a different particle size than those on the other side. In some instances, this two sided abrasive article can be used in a manner in which both sides of the abrasive article abrade at the same time. For example, in a small area such as a corner, one side of the abrasive article can abrade the top workpiece surface, while the other side can abrade the bottom workpiece surface.

Nonwoven Abrasive Articles

Nonwoven abrasive articles are also within the scope of the invention and include an open, lofty fibrous substrate having a binder which binds fibers at points where they contact. Optionally, abrasive particles or nonabrasive particles (such as fillers) may be adhered to the fibers by the binder if the manufacturer desires. For example, with reference to FIG. 3, a nonwoven abrasive comprises an open lofty fibrous substrate comprising fibers 50 with nodules 51 thereon; the nodules comprising binder 54, which binds a plurality of abrasive particles 52 to the fibers, and peripheral coating 56, comprising an antiloading component of the present invention, coated over at least a portion of binder 54 and abrasive particles 52. FIG. 4 illustrates a cross-section of nodule 51 showing peripheral coating 56, comprising an antiloading component of the present invention, present over at least a portion of the binder 54 and abrasive particles 52.

Nonwoven abrasives are described generally in U.S. Pat. Nos. 2,958,593 (Hoover et at.) and 4,991,362, which are incorporated herein by reference. In the present invention, an antiloading component is present in a peripheral coating over at least a portion of the binder.

Bonded Abrasive Articles

Bonded abrasive articles are also within the scope of the invention. A bonded abrasive article comprises a binder which adheres abrasive particles together in the form of a molded product. Bonded abrasives are described generally in U.S. Pat. No. 4,800,685 (Haynes), incorporated herein by reference. In the present invention, an antiloading component is present in a peripheral coating over at least a portion of the binder.

Methods of Making Abrasive Articles

Coated Abrasive Articles

Coated abrasive articles of the present invention may be prepared using coatable binder precursors. These binder precursors may be used independently, to form a treatment coating for the backing, for example, a back coating (backsize coat), front coating (presize coat), or saturant coating; a make coat to which abrasive particles are initially anchored; a size coat for tenaciously holding abrasive particles to the backing, or any combination of the aforementioned coatings. In addition, a binder precursor can be used in coated abrasive article embodiments where only a single coating binder is employed, i.e., where a single coating takes the place of a make coat/size coat combination, for example, in a lapping coated abrasive.

When a coatable binder precursor described herein is applied to a backing in one or more treatment steps to form a treatment coating, the treatment coating can be cured, e.g., thermally by passing the treated backing over a heated drum; there is no need to festoon cure the backing in order to set the treatment coating or coatings.

Reference to preparing a coated abrasive article having a make and size coat is set forth. After the backing has been properly treated with a treatment coating, if desired, a make coat binder precursor can be applied. After the make coat binder precursor is applied, abrasive particles can be applied into and over the make coat binder precursor. The abrasive particles can be drop coated or electrostatically coated. Next, the make coat binder precursor, now bearing abrasive particles, can be exposed to a source which generally solidifies or sets the binder sufficiently to hold the abrasive particles to the backing, e.g., a heat source. In some instances, the make coat binder precursor can be partially cured before the abrasive particles are embedded into the make coat as described in U.S. Pat. No. 5,368,618 (Masmar et al.). Then, a size coat binder precursor can be applied. The make coat binder precursor and/or size coat binder precursor can be applied by any suitable method including roll coating, spraying, die coating, curtain coating, and the like. The temperature of the make coat binder precursor and/or size coat binder precursor can be room temperature or higher, preferably from 30.degree. to 60.degree. C., more preferably from 30.degree. and 50.degree. C. The size coat binder precursor/abrasive particle/(at least partially cured) make coat combination can be exposed to a heat source, for example, via a festoon or drum cure, or, alternatively, a radiation source. This process will substantially cure or set the make and size coat binder precursor used in the coated abrasive constructions. Standard thermal cure conditions can be used to effect curing, for example, temperatures between 50.degree. to 150.degree. C., typically 75.degree. to 120.degree. C., preferably 80.degree. to 115.degree. C.

It is also feasible to use a hot melt binder precursor, for example as disclosed in WO 95/11111, incorporated herein by reference, to form a coated abrasive article. The hot melt make coat binder precursor can be prepared by mixing the components of the hot melt resin in a suitable vessel, preferably one that is not transparent to actinic radiation, at an elevated temperature sufficient to liquify the materials so that they may be efficiently mixed but without thermally degrading them (e.g., a temperature of about 120.degree. C.) with stirring until the component(s) are thoroughly melt blended. The components may be added simultaneously or sequentially. One preferred hot melt binder precursor comprises an epoxy-containing material, a polyester component having hydroxyl-containing end groups, and an initiator, preferably a photoinitiator, for example, as disclosed in U.S. Pat. No. 5,436,063 (Follett et al.), incorporated herein by reference.

It is also possible to provide the hot melt make coats as uncured, unsupported rolls of tacky, pressure sensitive adhesive film. Such films are useful in laminating the make coat to an abrasive article backing. It is desirable to roll the tacky film up with a release liner (for example, silicone-coated Kraft paper), with subsequent packaging in a bag or other container that is not transparent to actinic radiation.

The hot melt make coats may be applied to the abrasive article backing by extruding, gravure printing, or coating, (e.g., by using a coating die, a heated knife blade coater, a roll coater, a curtain coater, or a reverse roll coater). When applying by any of these methods, it is preferred that the make coat be applied at a temperature of about 100.degree. to 125.degree. C., more preferably from about 80.degree. to 125.degree. C. Coating is a desirable application method for use with J weight cloth backings and other fabric backings of similar porosity.

The hot melt make coats can be supplied as free standing, unsupported pressure sensitive adhesive films that can be laminated to the backing and, if necessary, die cut to a predefined shape before lamination. Lamination temperatures and pressures are selected so as to minimize degradation of the backing and bleed through of the make coat and may range from room temperature to about 120.degree. C. and about 30 to 250 psi. A typical profile is to laminate at room temperature and 100 psi. Lamination is a particularly preferred application method for use with highly porous backings, for example, as described in WO 95/11111, incorporated herein by reference.

Preferably, the hot melt make coat is applied to the abrasive article backing by any of the methods described herein, and once so applied is exposed to an energy source to initiate the curing of the epoxy-containing material. The epoxy-containing material is believed to cure or crosslink with itself.

In an alternative manufacturing approach, the make coat is applied to the backing and the abrasive particles are then projected into the make coat followed by exposure of the make coat to an energy source.

A size coat may be subsequently applied over the abrasive particles and the make coat as a flowable liquid by a variety of techniques such as roll coating, spray coating or curtain coating and can be subsequently cured by drying, heating, or with electron beam or ultraviolet light radiation. The particular curing approach may vary depending on the chemistry of the size coat.

A structured coated abrasive may be prepared as described in assignees' U.S. Pat. Nos. 5,152,917 (Pieper et al) and 5,435,816 (Spurgeon et al.), both of which are incorporated herein by reference. One method involves 1) introducing the abrasive slurry onto a production tool, wherein the production tool has a specified pattern; 2) introducing a backing to the outer surface of the production tool such that the slurry wets one major surface of the backing to form an intermediate article; 3) at least partially curing or gelling the resinous adhesive before the intermediate article departs from the outer surface of the production tool to form a structured coated abrasive article; and 4) removing the coated abrasive article from the production tool. Another method involves 1) introducing the abrasive slurry onto the backing such that the slurry wets the front side of the backing forming an intermediate article; 2) introducing the intermediate article to a production tool having a specified pattern; 3) at least partially curing or gelling the resinous adhesive before the intermediate article departs from the outer surface of the production tool to form a structured coated abrasive article; and 4) removing the structured coated abrasive article from the production tool. If the production tool is made from a transparent material, e.g., a polypropylene or polyethylene thermoplastic, then either visible or ultraviolet light can be transmitted through the production tool and into the abrasive slurry to cure the resinous adhesive. Alternatively, if the coated abrasive backing is transparent to visible or ultraviolet light, visible or ultraviolet light can be transmitted through the coated abrasive backing. In these two methods, the resulting solidified abrasive slurry or abrasive composite will have the inverse pattern of the production tool. By at least partially curing or solidifying on the production tool, the abrasive composite has a precise and predetermined pattern. The resinous adhesive can be further solidified or cured off the production tool.

A lapping coated abrasive can be prepared by coating an abrasive slurry onto at least one side of a backing. A preferred backing is a polymeric film, such as polyester film that contains a primer. Coating can be accomplished by spraying, rotogravure coating, roll coating, dip coating or knife coating. After the coating process, the slurry can be solidified, to form an abrasive coating, by exposure to an energy source including thermal and radiation energy (e.g., electron beam, ultraviolet light and visible light).

In all coated abrasive article embodiments of the present invention, a peripheral composition, which comprises an antiloading component, is applied over at least a portion of the binder of the coated abrasive article so that the antiloading component is capable of contacting a workpiece. The method of making a peripheral composition and forming a peripheral coating is described herein.

Nonwoven Abrasive Articles

A nonwoven abrasive article may be prepared by combining a binder precursor with abrasive particles and optional additives to form a coatable, binder precursor slurry. The slurry can be coated, for example, by roll coating or spray coating, onto at least a portion of the fibers of a lofty, open, fibrous web, and the resulting structure subjected to conditions sufficient to affect curing of the binder precursor, as described herein.

A general procedure for making lofty, open nonwoven abrasives includes those generally illustrated in U.S. Pat. No. 2,958,593, and those prepared according to the teachings of U.S. Pat. No. 4,991,362 and U.S. Pat. No. 5,025,596, all of which are hereby incorporated by reference.

A peripheral composition comprising an antiloading component is applied over at least a portion of the cured slurry to form a peripheral coating so that the antiloading component of the peripheral coating is capable of contacting a workpiece. The method of making a peripheral composition and forming a peripheral coating is described herein.

Bonded Abrasive Articles

A general procedure for making a bonded abrasive of the invention includes mixing together binder precursor, abrasive particles, and optional additives to form a homogenous mixture. This mixture is then molded to the desired shape and dimensions. The binder precursor is then subjected to conditions, described herein, sufficient to affect curing and/or solidification to form a bonded abrasive.

A peripheral composition comprising an antiloading component is applied over at least a portion of the molded product to form a peripheral coating so that the antiloading component of the coating is capable of contacting a workpiece. The method of making a peripheral composition and forming a peripheral coating is described herein.

Binder System

A binder in accordance with the present invention comprises a cured or solidified binder precursor and serves to adhere a plurality of abrasive particles together (as in a bonded abrasive article) or to a substrate (i.e., a backing for a coated abrasive or a nonwoven for a nonwoven abrasive).

The term "binder precursor" as used herein refers to an uncured or a flowable binder.

Organic binders suitable for an abrasive article of the present invention are formed from an organic binder precursor; it is, however, within the scope of the present invention to use a water-soluble binder precursor or water-dispersible binder precursor, such as hide glue. The binder precursor is preferably a thermosetting resin. Examples of thermosetting resins include phenolic resins, aminoplast resins having pendant .alpha.,.beta.-unsaturated carbonyl groups, urethane resins, epoxy resins, urea-formaldehyde resins, isocyanurate resins, melamine-formaldehyde resins, acrylate resins, acrylated isocyanurate resins, acrylated urethane resins, acrylated epoxy resins, bismaleimide resins, and mixtures thereof.

Phenolic resins are commonly used as an abrasive article binder precursor because of their thermal properties, availability, cost and ease of handling. There are two types of phenolic resins, resole and novolac. Resole phenolic resins have a molar ratio of formaldehyde to phenol, of greater than or equal to one to one, typically between 1.5:1.0 to 3.0:1.0. Novolac resins have a molar ratio of formaldehyde to phenol, of less than one to one. The phenolic resin is preferably a resole phenolic resin. Examples of commercially available phenolic resins include those known under the trade designations "Varcum" and "Durez" from Occidental Chemical Corp., Tonawanda, N.Y.; "Arofene" and "Arotap" from Ashland Chemical Company, Columbus, Ohio; "Resinox" from Monsanto, St. Louis, Mo.; and "Bakelite" from Union Carbide, Danbury, Conn.

It is also within the scope of the present invention to modify the physical properties of a phenolic resin. For example, a plasticizer, latex resin, or reactive diluent may be added to a phenolic resin to modify flexibility and/or hardness of the cured phenolic binder.

A preferred aminoplast resin is one having at least one pendant .alpha.,.beta.-unsaturated carbonyl groups per molecule, which can be prepared according to the disclosure of U.S. Pat. No. 4,903,440 (Larson et al.) which is incorporated herein by reference.

Aminoplast resins have at least one pendant .alpha.,.beta.-unsaturated carbonyl group per molecule or oligomer. These unsaturated carbonyl groups can be acrylate, methacrylate or acrylamide type groups. Examples of such materials include N-hydroxymethyl-acrylamide, N,N'-oxydimethylenebisacrylamide, ortho and para acrylamidomethylated phenol, acrylamidomethylated phenolic novolac and combinations thereof. These materials are further described in U.S. Pat. Nos. 4,903,440; 5,055,113; and 5,236,472 all incorporated herein by reference.

Polyurethanes may be prepared by reacting near stoichiometric amounts of polyisocyanates with polyfunctional polyols. The more common types of polyisocyanates are toluene diisocyanate (TDI) and 4,4'-diisocyanatodiphenylmethane (MDI) which are available under the trade designations "Isonate" from Upjohn Polymer Chemicals, Kalamazoo, Mich. and "Mondur" from Miles, Inc., Pittsburgh, Pa. Common polyols for flexible polyurethanes are polyethers such as polyethylene glycols, which are available under the trade designations "Carbowax" from Union Carbide, Danbury, Conn.; "Voranol" from Dow Chemical Co., Midland, Mich.; and "Pluracol E" from BASF Corp., Mount Olive, N.J.; polypropylene glycols, which are available under the trade designations "Pluracol P" from BASF Corp. and "Voranol" from Dow Chemical Co., Midland, Mich.; and polytetramethylene oxides, which are available under the trade designations "Polymeg" from QO Chemical Inc., Lafayetts, Ind.; "Poly THF" from BASF Corp., Mount Olive, N.J.; and "Tetrathane" from DuPont, Wilmington, Del. Hydroxyl functional polyesters are available under the trade designations "Multranol" and "Desmophene" from Miles, Inc., Pittsburgh, Pa. Virtually all polyurethane formulations incorporate one or more catalysts. Tertiary amines and certain organometallic compounds, especially those based on tin, are most common. Combinations of catalysts may be used to balance the polymer-formation rate.

Epoxy resins have an oxirane ring and are polymerized by the ring opening. Such epoxide resins include monomeric epoxy resins and polymeric epoxy resins. These resins can vary greatly in the nature of their backbones and substituent groups. For example, the backbone may be of any type normally associated with epoxy resins and substituent groups thereon can be any group free of an active hydrogen atom that is reactive with an oxirane ring at room temperature. Representative examples of acceptable substituent groups include halogens, ester groups, ether groups, sulfonate groups, siloxane groups, nitro groups and phosphate groups. Examples of some preferred epoxy resins include 2,2-bis[4-(2,3-epoxypropoxyphenol)propane (diglycidyl ether of bisphenol A)] and commercially available materials under the trade designations, "Epon 828", "Epon 1004", and "Epon 1001F", available from Shell Chemical Co., Houston, Tex.; "DER-331", "DER-332", and "DER-334" available from Dow Chemical Co., Midland, Mich. Other suitable epoxy resins include glycidyl ethers of phenol formaldehyde novolac (e.g., "DEN-431" and "DEN-438" available from Dow Chemical Co., Midland, Mich.). Other epoxy resins include those described in U.S. Pat. No. 4,751,138 (Tumey et al.), incorporated herein by reference.

Urea-aldehyde resins employed in binder precursor compositions of the present invention may be comprised of a reaction product of urea or any urea derivative and any aldehyde which are capable of being rendered coatable, have the capability of curing together at an accelerated rate in the presence of a catalyst, preferably a cocatalyst, and which afford an abrasive article with abrading performance acceptable for the intended use. Urea-formaldehyde resins are generally preferred in the abrasive industry, as noted above, because of their availability, low cost, and ease of handling. Urea-aldehyde resins preferably are 30-95% solids, more preferably 60-80% solids, with a viscosity ranging from about 125 to about 1500 cps (Brookfield viscometer, number 3 spindle, 30 rpm 25.degree. C.) before addition of water and catalyst and have molecular weight (number average) of at least about 200, preferably varying from about 200 to 700. Urea aldehyde resin useful for the present invention include those described in U.S. Pat. No. 5,486,219 (Ford et al.), incorporated herein by reference.

A particularly preferred urea-aldehyde resin for use in the present invention is that known under the trade designation AL3029R, from Borden Chemical. This is an unmodified (i.e. contains no furfural) urea-formaldehyde resin with these characteristics: 65% solids, viscosity (Brookfield, #3 spindle, 30 rpm 25.degree. C.) of 325 cps, a free formaldehyde content of 0.1-0.5%, and a mole ratio of formaldehyde to urea ("F/U ratio") ranging from about 1.4:1.0 to about 1.6:1.0.

Urea resin binder precursor systems preferably employ a cocatalyst system. The cocatalyst may consist essentially of a Lewis acid, preferably aluminum chloride (AlCl.sub.3), and an organic or inorganic salt. A Lewis acid catalyst is defined simply as a compound which accepts an electron pair, and preferably has an aqueous solubility at 15.degree. C. of at least about 50 grams/cc.

Lewis acids (or compounds which behave as Lewis acids) which are preferred are aluminum chloride, iron (III) chloride, and copper (II) chloride. A Lewis acid which is particularly preferred is aluminum chloride in either its non-hydrated form (AlCl.sub.3) or hexahydrate from (AlCl.sub.3 6H.sub.2 O).

The Lewis acid is typically and preferably used in the binder precursor system at an amount ranging from about 0.1 to about 5.0 weight percent of the total weight of binder precursor, as a 20-30% solids aqueous solution. If aluminum chloride (AlCl.sub.3) is used, it has been found that 0.6 weight percent of a 28% solids aqueous solution of AlCl.sub.3 gives preferable results.

Acrylate resins include both monomeric and polymeric compounds that contain atoms of carbon, hydrogen and oxygen, and optionally, nitrogen and the halogens. Oxygen or nitrogen atoms or both are generally present in ether, ester, urethane, amide, and urea groups. Ethylenically unsaturated compounds preferably have a molecular weight of less than about 4,000 and are preferably esters made from the reaction of compounds containing aliphatic monohydroxy groups or aliphatic polyhydroxy groups and unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and the like. Representative examples of acrylate resins include methyl methacrylate, ethyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate and pentaerythritol tetramethacrylate, as well as these unsaturated monomers, for example, styrene, divinylbenzene, vinyl toluene.