CA2247273A1 - Radiation curable abrasive article with tie coat and method - Google Patents

Abstract

A method of preparing an abrasive article, and the article produced therefrom is provided. The method includes the steps of: providing a backing having a first major surface; coating the first major surface of the backing with a tie coat precursor, wherein the tie coat precursor comprises a first radiation curable component; applying an abrasive slurry to the first major surface of the backing after coating the tie coat precursor thereon, wherein the abrasive slurry comprises a plurality of abrasive particles and a binder precursor, and further wherein the binder precursor comprises a second radiation curable component; at least partially curing the tie coat precursor; and at least partially curing the binder precursor to form an abrasive article, wherein the abrasive article comprises a backing, an abrasive layer, and a tie coat disposed between the backing and the abrasive layer. Preferably, the method provides a structured abrasive article.

Description

W O 97/~3719 PCTrUS97/01322 RADIATION CURABLE ABRASIVE ARTICLE
WITH TIl~ COAT AND METHOD

Back~round of the Invention 5This invention relates to radiation curable abrasive articles, particularly to structured abrasive articles, having a tie coat that çnh~nces adhesion of the abrasive layer to the backing.
For many years, conventional cloth backed coated abrasive articles utilized one or more treatment coats con~i.cting of animal glues, starches, latices, thermally 10 curable resins such as phenolic-based tre~tn çnt coats or phenolic/latex tre~tment coats, and thermally cured phenolic-based binders in the abrasive coating. Thesecombinations result in generally good adhesion between the tre~tment coat(s) andthe fibers in the cloth backing and between the abrasive binder and the tre~tment coat(s). In recent years, some coated abrasive articles, particularly structuredabrasive articles as disclosed in U.S. Patent Nos. 5,152,917 (Pieper et al.) and5,435,816 (Spurgeon et al.), have begun employing radiation cured binder systems, such as acrylate-based binders, in the abrasive layer instead of the phenolic-based binders. For some applications, the adhesion between conventional b~ç~ing treatment coats, e.g., saturant coats, presize coats, and the like, and these new 20 radiation cured binders is not as strong as desired, sometimes res lltinf~ in .ch.olling, depending on the particular abrading application. This is true particularly if acontinuous m~mlf~ctllring process is used for making the abrasive article and relatively high processing speeds are used. Thus, what is needed is a system by which radiation cured binders, such as acrylate-based binders, can be used on 25 treated cloth backings and produced in a continuous m~mlf~cturing process using relatively high processing speeds, with good adhesion.

W 0 971~3719 PCT~US97/01322 Summarv of the Invention The present invention provides a method of plei)a,;l1g an abrasive article, the method comprising: providing a backing having a first major surface; coatingthe first major surface of the backing with a tie coat precursor, wherein the tie coat 5 precursor comprises a first radiation curable component; applying an abrasive slurry to the first major surface of the backing after coating the tie coat precursor thereon, whereill the abrasive slurry comprises a plurality of abrasive particles and a binder precursor, and further wherein the binder precursor col~lp,;ses a second radiation curable component; at least partially curing the tie coat precursor; and at least 10 partially curing the binder precursor to form an abrasive article, wherein the abrasive article comprises a backing, an abrasive layer, and a tie coat disposedbetween the backing and the abrasive layer. Preferably, the curing steps are carried out using radiation energy.
The step of at least partially curing the tie coat precursor can occur prior to 15 the step of applying an abrasive slurry. Alternatively, the steps of at least partially curing the tie coat precursor and at least partially curing the binder precursorcontained in the abrasive slurry occur substantially simultaneously (i.e., during the sarne curing stage of the process). Thus, when the abrasive slurry is applied to the first major surface of the backing, the tie coat precursor can be uncured, at least 20 partially cured, or subst~nti~lly cured. The phrase ~'tie-coated backing" is therefore used herein to refer to the backing when the abrasive slurry is coated thereon, and encompasses the embodimçnt~ wherein the backing is coated with an uncured tie coat precursor, a partially cured tie coat precursor, or a subst~nti~lly cured tie coat.
Preferably, the tie coat precursor and binder precursor include 25 acrylate-functional compounds. More preferably, they each include an acrylatemonomer and an isocyanurate derivative having at least one pendant acrylate group.
In particularly pl e~- l ed embodiments, the tie coat precursor has the same composition as the binder precursor used in the abrasive slurry.
The present invention also provides a method of plepa~h~g an abrasive 30 article, the method comprising: providing a treated cloth backing having a first major surface; coating the first major surface of the treated cloth backing with a tie W O 97/~3719 r ~ rUS97tO1322 coat precursor, wherein the tie coat precursor col.l~lises a first radiation curable component; providing a radiation energy tr~n.~mi~.~ive production tool having a cont~cting surface; applying an abrasive slurry onto the cont~ctin~ surface of the production tool, wherein the abrasive slurry comprises a plurality of abrasive particles and a binder precursor, and further wherein the binder precursor comprises a second radiation curable component; causing the abrasive slurry on the cc)nt~c~in~
surface of the production tool to come into contact with the first major surface of the backing after coating the tie coat precursor thereon; at least partially curing the tie coat precursor; trar-~mitting radiation energy through the production tool to at least partially cure the binder precursor to form a shaped, handleable structure; and sepal~ g the shaped, h~nflle~ble structure from the production tool to forrn an abrasive article, wherein the abrasive article comprises a treated cloth baç~ing, an abrasive layer, and a tie coat disposed between the treated cloth bacl~ing and the abrasive layer. As used herein, a shaped, handleable structure refers to the abrasive slurry when the binder precursor contained therein is at least partially cured, such that it is solidified sufficiently to be removed from the production tool without substantially losing the topographical pattern imparted by the production tool.
Also provided is an abrasive article comprising: a cloth backing having a first major surface; a radiation cured tie coat on the first major surface of the bac~ing; and an abrasive layer on the radiation cured tie coat, wherein the abrasive layer comprises a plurality of abrasive particles dispersed in a radiation curedbinder. Preferably, this article is a structured abrasive article.

Detailed Description The present invention provides a method of preparing an abrasive article having improved adhesion of an abrasive layer to a b~c~ing pler~-~bly a cloth backing, and more preferably a treated cloth backing. The method is preferably carried out as a continuous process, and is particularly advantageous at relatively high run speeds. The method involves coating the backing with a tie coat precursor, applying an abrasive slurry comprising abrasive particles and a binder precursor to this tie-coated backing, at least partially curing the tie coat precursor, W O 971~3719 PCTAUS97/01322 and at least partially curing the binder precursor to form an abrasive article. The tie coat precursor can be at least partially cured prior to the application of the abrasive slurry, or it can be at least partially cured subst~nti~lly ~imlllt~neously with the binder precursor. The tie coat precursor inrludes a radiation curable component, as S does the binder precursor used in the abrasive slurry, which may be the same or dirre~ . Preferably, the tie coat precursor has the same composition as the binder precursor used in the abrasive slurry.
Typically, slurry coated abrasive articles, such as structured abrasive articlesas disclosed in U.S. Patent Nos. 5,152,917 (Pieper et al.) and 5,435,816 10 (Spurgeon et al.), are made using a continuous m~nllf~ctl-ring process. They utilize radiation curable binder systems, such as acrylate-based binder precursors, in the abrasive slurry, that are typically cured with radiation energy during the continuous process. The speed at which this process is run, however, can be limited by the level of adhesion of the cured abrasive slurry (i.e., the abrasive layer) to the backing lS that can be obtained. Typically, speeds of less than 15.5 meters/minute are used to ensure adequate adhesion of the abrasive slurry to the backing. At speeds higherthan this, however, adhesion of the abrasive slurry tends to rlimini~h, which can be undesirable for certain applications.
The use of a tie coat p-~pared from a radiation curable system provides 20 significant improvement in ~-lhesion of the abrasive layer to the b~cl~ing, particularly at abrasive-making line speeds of at least about 25 meters/minute, prere~ably at line speeds of at least about 50 meters/minute, more preferably at least about 75 meters/minute, and even at line speeds as high as about 100 meters/minute, for at least partial cure of the binder precursor in the abrasive slurry and optionally the 25 tie coat precursor. As used herein, "line speed" refers to the rate at which the backing travels through the coating process, which includes applying the abrasive slurry to the backing and at least partially curing the binder precursor of the abrasive slurry. The coating process to which this "line speed" refers may include applying the tie coat precursor and at least partially curing the tie coat precursor.
30 That is, although the tie coat precursor can be applied to the backing and at least partially cured during the process in which the abrasive slurry is applied, these steps W O 97/~3719 PCTrUS97/01322 can be carried out in a previous coating process and the tie-coated b~el~ing stored prior to application of the abrasive slurry.
The abrasive articles produced by this method are prepared from an abrasive slurry coated on a backing to provide a generally con~im-Qus layer of abrasive 5 particles dispersed in a binder. This is referred to herein as a coated abrasive article, and more specifically as a slurry coated abrasive article. To enhance adhesion of the abrasive layer to the backing, a tie coat is disposed between the baç~ing, optionally coated with one or more conventional tre~m~nt coat(s), and the abrasive layer. The abrasive layer may have a smooth, textured, embossed, 10 structured, etc., surface.
One particularly prerel.ed method of making such a slurry coated abrasive article incllldes placing the abrasive slurry into a mold to form a plurality ofindividual shaped abrasive precursor composites, which is then brought into contact with the backing, and subsequently at least partially cured to provide a shaped,15 handleable structure such that the tooling can be removed. The res~llt~nt product is referred to herein as a structured abrasive article comprising shaped abrasive composites. The individual shaped abrasive composites are three-dimensional withwork surfaces that contact the workpiece during grinding.
It is plerelled that these shaped abrasive composites be "precisely" shaped.
20 This means that the shape of the composites is defined by relatively smooth surfaced sides that are bounded and joined by well-defined edges having distinctedge lengths with distinct endpoints defined by the intersections of the varioussides. The terms "bounded" or"boundary" means the exposed surfaces and edges of each composite that delimit and define the actual three-dimensional shape of each 25 abrasive composite. These boundaries are readily visible and discernible when a cross-section of an abrasive article is viewed under a scanning electron microscope.
These boundaries separate and di.~tingllish one abrasive composite from another even if the composites abut each other along a common border at their bases. By comparison, in an abrasive composite that does not have a precise shape, the 30 boundaries and edges are not well defined, e.g., where the abrasive composite sags WO 97/~3719 PCT/US97tO1322 before completion of its curing. In some in~t~nces, it is prefc~ed that these abrasive composites be arranged on the bar~ing in a predetermined pattern or array.
Referring to Figure 1, structured abrasive article 10 inr.l~1des bacl~in~ 11 having front surface 12 and back surface 13. The baçl~in~ can further include 5 optional backfill coat 14 that coats the backing, and optional presize coat 15 applied to the front surface 12 of the backing. To enh~nce adhesion of structured abrasive layer 17 to backing 11, tie coat 16 is disposed between bacl~in~ 11 (optionally coated with either backfill coat 14, presize coat 15, or both) and structured abrasive layer 17. Structured abrasive layer 17 inellldes abrasive composites 18 con,l,.isi-.g 10 a plurality of abrasive particles 19 dispersed in binder 20.

Backing The backing used in the abrasive articles of this invention has a front and back surface (i.e., a first and a second major surface) and can be any suitable 15 material typically used for conventional abrasive baç~ing.c. Examples of suchmaterials include primed and unprimed polymeric film, cloth, paper, vl.lc~ni~:edfibre, nonwoven webs, and combina~ions thereof. The backing may also contain a treatment or ~. eaLl~c~l~s to seal the backing and/or modify the physical properties of the baç1ring These treatm~nt~ are well known in the art, and are ~lisc~ssed in 20 greater detail below.
The prefelled backing of the invention is a cloth backing. The cloth is composed of yarns in the warp direction, i.e., the m~çhine direction and yarns in the fill direction, i.e., the cross direction. The cloth backing can be a woven backing, a stitchbonded backing, or a weft insertion backing. Examples of woven 25 constructions include sateen weaves of four over one weave of the warp yarns over the fill yarns; twill weaves of three over one weave; plain weaves of one over one weave; and drill weaves of two over one weave. In a stitchbonded fabric or weft insertion bac~in~ the warp and fill yarns are not interwoven, but are oriented in two distinct directions from one another. The warp yarns are laid on top of the fill 30 yarns and secured to another by a stitch yarn or by an adhesive.

CA 02247273 l998-08-24 W O 97t~3719 PC~US97/01322 The yarns in the cloth b~ in~ can be natural, synthetic, or cGI~binalions thereof. The yarns can be twisted or te~ e(~ FY~mples of natural yarns include cellulosics such as cotton, hemp, kapok, flax, sisal, jute, manila and conlbilldlions thereof. Examples of synthetic yarns include polyester yarns, polypropylene yarns, 5 glass yarns, polyvinyl alcohol yarns, polyimide yarns, aromatic polyamide yarns, regenelated cellulose yarns such as rayon yarns, nylon yarns, polyethylene yarns, and combinations thereo~ The pr~re-led yarns of this invention are polyester yarns, nylon yarns, a mixture of polyester and cotton, cellulosic yarns, and aromatic polyamide yarns.
Polyester yarns are formed from a long chain polymer made from the reaction of an ester of dihydric alcohol and terephthalic acid. Ple~,~bly, this polymer is a linear polymer of poly(ethylene terephth~l~te). There are three main types of polyester yarns: ring spun; open end; and fil~m~nt. A ring spun yarn ismade by continuously drafting a polyester yarn, twisting the yarn and winding the lS yarn on a bobbin. An open end yarn is made directly from a sliver or roving. A
series of polyester rovings are opened and then all of the rovings are continuously brought together in a spinning appa~ s to form a continuous yarn. A fil~ment yarn is a long continuous fiber; a fil~m~o.nt yarn typically has a very low or non-exi.c~tçnt twist to the polyester fiber.
The denier of the fibers should be less than about 2000, preferably about 100-1500. The yarn size should be within a range of about 1500-12,000 meters/kilogram. For a coated abrasive cloth backing, the weight of the greige cloth, i.e., the untreated cloth or raw cloth, will be within a range of about O.1-ltkg/m2, preferably within a range of about 0.1-0.75 kg/m2. Untreated ~r~
weight cloth typically has a weight of about 130-l9S g/m2, "X' weight cloth typically has a weight of about 200-245 g/m2, and "Y" weight cloth typically has a weight of about 270-330 g/m2. The cloth backing should also have a high surface area.
Coated abrasive cloth b~clring~ can be dyed, stretched, deci7ed~ or heat set.
Additionally, the yarns in the cloth backing can contain primers, dyes, pigments, or wetting agents. The cloth backings can also have a variety of tre~trn~nt coats, such W O 97/~3719 PCTAUS97/01322 as a saturant coat, presize coat, baçkci7.~ coat, subsize coat, bacl~lll coat, frontfill coat, and the like. As used herein, a ~'treated" cloth backing refers to a clothbac~in~ that has at least one such ~re~ll..rnt coat. This does not include cloth that does not have a residual coating thereon, such as cloth that has been desized or heat 5 set.
Preferably, the cloth backing in~ de~ at least one of these treatment coats The purpose of these tre~tm~nt coats is to seal the backing and/or protect the yarns or fibers in the backing, reduce stretch, improve heat re~i~t~nce, improve moisture reci.ct~nce, tailor flexibility, and/or improve adhesion. The addition of one or more 10 of these tre~tm~nt coats may additionally result in a "smoother" surface on either the front or back side of the backing.
Af~er any one of the treatment coats is applied to the cloth bac.~ing the reslllt~nt treated cloth backing can be heat treated or calendered. The heat Llea~ can be carried out in a tenter frame which is in an oven. Additionally the15 backing can be processed through heated hot cans. The calendering step will remove surface roughness and typically increase the surface smoothness.
Conventional cloth l~c~ c, whether they be applied as saturant coats, presize coats, back~i7e coats, backfill coats, frontfill coats, etc., include various starches, gums, dextrins, animal glues, urea-formaldehyde resins, poly(vinyl alcohol) 20 and poly(vinyl acetate) resins and latices, ethyl cellulose, nitrile latices,styrene/butadiene latices, vinyl and rubber latices, epoxies, phenolic resins, acrylate resins, acrylic latices, urethane resins, vinyl ether-functional resins, and c~...hi~-~tions thereof. Pl~relled cloth l,~ enl.~; for use with the radiation curable materials used in the tie coat precursor of the present invention include poly(vinyl acetate) latices, nitrile latices, stryene/butadiene latices, acrylic latices, phenolic resins, and combinations thereof. Particularly pleI~I~ed cloth tre~t~nt.c for use with the radiation curable materials used in the tie coat precursor of the present invention include acrylic latices, phenolic resins, and combinations thereof Suitable ac~ylic latices are those forming films having the following physical properties:
glass transition temperatures of about -50~C to about +40~C, preferably about -5~C
to about +35~C; tensile strength of at greater than about 1.38 MPa, preferably W O 97/~3719 ~ PCTAUS97/01322 greater than about 6.89 MPa, and elongation of greater than about 10%, preferably less than about 5000%, and more preferably about 250-1000%. Such acrylic laticesare commercially avallable from B.F. Goodrich Co., Cleveland, OH, ~to~c North America, Inc., Bristol, PA, Air Products and Chemicals, Inc., Reichhold ChemicalS Co. Suitable phenolic resins are water miscible and forrn continuous homogenous - films with the selected acrylic latex. Such phenolic resins are co~ nt;l~i;all available from Occidçnt~l Chemical Corp., Dallas, TX; Georgia Pacific Resins, Inc Columbus, OH; Ashland Chemical Co., Columbus, OH; ~on~nto, St. Louis, MO;
and l~k~.lite, Letm~th~, Germany.
Tie Coat and Binder Systems The binder system used in the abrasive layer in the abrasive articles of the invention is formed from a binder precursor. The tie coat is forTned from a tie coat precursor. Both comprise a resinous adhesive in an uncured and flowable state that 15 is capable of solidifying. Both can include the same components, or they can be di~elell~, although they both include the following components. The solidific~tion can be achieved by curing (i.e., poly.~ .;n~ and/or cro~slinking) or by drying (e.g., or driving off a liquid) and curing. The binder and tie coat precursors can be organic solvent-borne, water-borne, or 100% solids (i.e., a subst~nti~lly 20 solvent-free) compositions. That is, the binder and tie coat may be formed from a 100% solids formulation or they may be coated out of a solvent (e.g., a ketone, tetrahydrofuran, or water) with subsequent drying and curing. If a solvent is used, it is one that does not react with the other components of the precursors,but can be driven off by heat, for example, although complete elimin~tion is not25 nece.s~rily required. Preferably, both the tie coat precursor and the binde}
precursor are 100% solids formulations that are substantially solvent-free (i.e., contain less than about 1 wt-% solvent).
The binder and tie coat precursors are capable of irreversibly forming a cured oligomeric/polymeric m~ttori~l and are often referred to as "thermosetting"
30 precursors. The term " thermosetting" precursor is used herein to refer to reactive systems that irreversibly cure upon the application of heat and/or other g WO 97/~3719 PCT/US97/01322 sources of energy, such as E-beam, ultraviolet, visible, etc., or with time uponthe addition of a chemical catalyst, moisture, or the like. The term "reactive"
means that the components of the binder and tie coat precursors react with each other (or self react) either by polym~.ri7.in~, cros.~linkin~, or both. These 5 colnpol1ents are often referred to as resins. As used herein, the term "resin" refers to polydisperse systems co~ monomers, oligomers, polymers, or col,lbin~lions thereof.
M~t~ri~l.c suitable for forming the abrasive binder and the tie coat ~e precursors comprising reactive components (i.e., conl~llents capable of being 10 cros~linked and/or polymeri7e~1) that are curable using Mdiation. These are referred to herein as radiation curable m~tPri~ls. As used herein, "radiation curable" refers to curing mech~ni.cm~ that involve polymerization and/or cros.~linking of resin systems upon exposure to ultraviolet radiation, visible radiation, electron bearn radiation, or combinations thereof, optionally with the 15 applop~iate catalyst or initiator. Typically, there are two types of radiation cure me~.h~ni.~m.~ that occur -- free radical curing and cationic curing. These usually involve one stage curing or one type of curing me~h~ni~m Suitable materials for use in the abrasive articles of the present invention are free radical curable materials;
however, mixtures of free radical and cationic materials may also be cured to impart 20 desired properties from both systems. Also possible are dual-cure and hybrid-cure systems, as ~i~c~lssed below, as long as the system incl~lde, a material capable of .
radlatlon curmg.
In cationic systems, cationic photoiniti~tors react upon exposure to ultraviolet/visible light to decompose to yield an acid catalyst (e.g., a protonic acid 25 or Lewis acid). The acid catalyst propagates a cro.c.~linl-ing reaction via an ionic meçh~nism Epoxies, particularly cycloaliphatic epoxies, are the most common resins used in cationic curing, although aromatic epoxies and vinyl ether based oligomers can also be used. Furthermore, polyols can be used in cationic curing with epoxies as chain-transfer agents and flexibilizers. Also, epoxysiloxanes as30 disclosed in Eckberg et al., "W Cure of Epoxysiloxanes," Radiation Curing in Polymer Science and Technolo~y: Volume IV~ Practical Aspects and Applications~

WO 97/~3719 PCT/US97101322 Fouassier and Rabek, eds., Elsevier Applied Science, NY, Chapter 2, 19-49 (1993)can be cured using a cationic photoiniti~tor. The cationic photoinitiators include salts of onium cations. such as arylsulfonium salts, as well as or~ ometalliç salts ~ such as iron arene systems. F~r~mrles of cationic photoinitiators are disclosed in S U.S. Patent Nos. 4,751,138 (Tumey et al.) and 4,985,340 (Palazzotti), and European Patent Application Nos. 306,161 and 306,162.
In free radical systems, radiation provides very fast and controlled generation of highly reactive species that initiate polymerization of unsaturated m~tPri~l~ Examples of free radical curable materials inrl~lde, but are not limited to, acrylate resins, aminoplast derivatives having pendant alpha,beta-unsaturated carbonyl groups, isocyanurate derivatives having at least one pendant acrylate group, isocyanate derivatives having at least one pendant acrylate group, unsaturated polyesters (e.g., the condensation products of organic diacids and glycols), and other ethylenically unsaturated compounds, and mixtures or combinations thereof. These free radical curable systems can be cured using radiation energy, although they can be cured using thermal energy, as long as there is a source of free radicals in the system (e.g., peroxide or azo compounds). Thus, the phrase "radiation curable," and more particularly the phrase "free radical curable," include within their scope systems that also can be cured using thermal energy and that involve a free radical curing meçh~nism In contrast, the phrase "radiation cured" refers to systems that have been cured by exposure to radiation energy.
Suitable acrylate resins for use in the present invention include, but are not limited to, monofunctional and mllltifilnctional acrylate monomers, as well as acrylated urethanes (i.e., urethane acrylates), acrylated epoxies (i.e., epoxy acrylates), acrylated polyesters (i.e., polyester acrylates), acrylated acrylics, and acrylated polyethers (i.e., polyether acrylates). As used herein, the terms "acrylate"
and "acrylate-functional" compound includes both acrylates and meth~crylates, whether they be monomers, oligomers, or polymers.
Examples of suitable monofunctional acrylate monomers include, but are not limited to, ethyl acrylate, ethyl methacrylate, ethyl acrylate, methyl W O 97~3719 PCTrUS97/01322 methacrylate, isooctyl acrylate, oxethylated phenol acrylate, isobornyl acrylate, 2-ethylhexyl acrylate, vinyl pyrrolidone, 2-phenoxyethyl acrylate, 2-(ethoxyethoxy)ethyl acrylate, ethylene glycol m~th~erylate, tetIahydroxy furfuryl acrylate (THF acrylate), caprolactone acrylate, and methoxy ~ opylene S glycol monoacrylate. FY~mrl~.~ of suitable multifunctional acrylate monomers include, but are not limited to, triethylene glycol diacrylate, pent~c~lhliLol triacrylate, trimethylolpropane triacrylate, pentaerythritol trimethAcrylate, glycerol triacrylate, trimethylolpropane trimethAcrylate, trimethylolpropane triacrylate, 1,6-he~AneAiol diacrylate, 1,4-butanediol diacrylate, tetramethylene glycol diacrylate, tripropylene glycol diacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, pentaerythritol tetraacrylate, pentaerythritol tetrAmethacrylate, and 1,6-hexane diacrylate. Such compounds are available under the trade cl~ n~tions EBECRYL from UCB
Radcure Inc., Smyrna, GA; PHOTOMER from Henkel Corp., Hoboken, NJ.;
and SARTOMER from Sartomer Co., West Chester, PA. Preferably, the tie coat and binder ~lecul~or compositions include a multifunctional acrylate monomer.
Acrylated urethanes are diacrylate esters of hydroxy termin~ted isocyanate extended polyesters or polyethers. They can be aliphatic or aromatic, although acrylated aliphatic urethanes are plefelled because they are less susceptible toweathering. Examples of commercially available acrylated urethanes include thoseknown by the trade design~tions PHOTOMER (e.g., PHOTOMER 6010) from Henkel Corp., Hoboken, NJ; EBECRYL 220 (hexafunctional aromatic urethane acrylate of molecular weight 1000), EBECRYL 284 (aliphatic urethane diacrylate of 1200 molecular weight diluted with 1,6-hexanediol diacrylate), EBECRYL 4827 (aromatic urethane diacrylate of 1600 molecular weight), EBECRYL 4830 (aliphatic urethane diacrylate of 1200 molecular weight diluted with tetraethylene glycol diacrylate), EBECRYL 6602 (trifunctional aromatic urethane acrylate of 1300 molecular weight diluted with trimethylolpropane ethoxy triacrylate), and EBECRYL 8402 (aliphatic urethane diacrylate of 1000 molecular weight) from UCB Radcure Inc., Smyrna, GA; SARTOMER (e.g., SARTOMER 9635, 9645, WO 97/~3719 PCT/US97/01322 9655, 963-B80, 966-A80, etc.) from Sartomer Co., West Chester, PA; and WITHANE (e.g., UVITHANE 782) from Morton International, Chicago, IL.
Acrylated epoxies are diacrylate esters of epoxy resins, such as the ~ diacrylate esters of bisphenol A epoxy resin. F.Y~mples of co.,llllelcially available S acrylated epoxies include those known by the trade de~i~n~tions EBECRYL 600 (bisph~on~ l A epoxy diacrylate of 525 molecular weight), EBECRYL 629 (epoxy novolac acrylate of 550 molecular weight), and EBECRYL 860 (epoxidized soya oil acrylate of 1200 molecular weight) from UCB Radcure Inc., Smyrna, GA; and PHOTOMER 3016 (bisphenol A epoxy diacrylate), PHOTOMER 3038 (epoxy 10 acrylate/Ltil)ropylene glycol diacrylate blend), PHOTOMER 3071 (modified bisphenol A acrylate), etc., from Henkel Corp., Hoboken, NJ.
Acrylated polyesters are the reaction products of acrylic acid with a dibasic acid/aliphatic/diol-based polyester. Examples of conll.,elcially available acrylated polyesters include those known by the trade designations PHOTOMER 5007 (hex~filnctional acrylate of 2000 molecular weight), PHOTOMER 5018 (tetrafunctional acrylate of 1000 molecul~r weight), and other acrylated polyesters in the PHOTOMER 5000 series from Henkel Corp., Hoboken, NJ; and EBECRYL
80 (tetrafunctional modified polyester acrylate of 1000 molecular weight), EBECRYL 450 (fatty acid modified polyester hexaacrylate), and EBECRYL 830 (h~filnctional polyester acrylate of 1500 molecular weight) from UCB Radcure Inc., Smyrna, GA.
Acrylated acrylics are acrylic oligomers or polymers that have reactive pendant or terminal acrylic acid groups capable of forming free radicals for subsequent reaction. Examples of commercially available acrylated acrylics include those known by the trade de~ign~tions EBECRYL 745, 754, 767, 1701, and 1755 from UCB Radcure Inc., Smyrna, GA.
Isocyanurate derivatives having at least one pendant acrylate group and isocyanate derivatives having at least one pendant acrylate group are further described in U. S. Patent No. 4,652,274 (Boetcher et al.). Preferred binder precursors and tie coat precursors of the present invention include an isocyanurate WO 97/~3719 PCT/US97/01322 derivative having at least one pendant acrylate group. The plert;lled isocyanurate is a triacrylate of tris(hydroxy ethyl) isocyanurate.
The aminoplast resins have at least one pendant alpha,beta-unsaturated carbonyl group per molecule or oligomer. These unsaturated carbonyl groups can 5 be acrylate, meth~çrylate, or acrylamide type groups. E~amples of resins with aclylamide groups include N-(hydroxymethyl)-acrylamide, N,N'-oxydimethylenebisacrylamide, ortho- and para-aclylamidomethylated phenol, acrylamidomethylated phenolic novolac, glycoluril acIylamide, acrylamidomethylated phenol, and con~ alions thereof. These materials are further described in U.S. Patent Nos. 4,903,440 (Larson et al.), 5,055,113 (Larson et al.), and 5,236,472 (Kirk et al.).
Other suitable ethylenically unsaturated resins include monomeric, oligomeric, and polymeric compounds, typically CO~ ester groups, acrylate groups, and amide groups. Such ethylenically Imc~t~ t~d compounds preferably 15 have a molecular weight of less than about 4,000. They are preferably esters made from the reaction of compounds con~ g aliphatic monohyd,o~y groups or aliphatic polyhydroxy groups and unsaturated carboxylic acids, such as acrylic acid, meth~crylic acid, itaconic acid, maleic acid, and the like. R~l~s~.n~ e examples of acrylates are listed above. Other ethylenically un~d~ul~ted resins 20 include monoallyl, polyallyl, and polymethallyl esters and amides of carboxylic acids, such as diallyl phth~l~te, diallyl adipate, N,N-diallyladipamide, styrene, divinylbenzene, vinyl toluene. Still others include tris(2-acryloyl-oxyethyl)-isocyanurate, 1 ,3,5-tri(2-methyacryloxyethyl)-s-triazine, acrylamide, methylacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, 25 N-vinylpyrrolidone, and N-vinylpiperidone.
In dual-cure resin systems, the polymerization or cro.s.clinkin~ occur in two separate stages, via either the same or ~lir~elelll reaction mech~ni.cms. Inhybrid-cure resin systems~ two mech~ni.cmc of polymerization or croc.clinking occur at the same time on exposure to ultraviolet/visible or E-beam radiation.
30 The chemical curing mech~nicmc that can occur in these systems include, but are not limited to, radical polymerization of acrylic double bonds, radical W O 97133719 PCT~US97/01322 polym~ri7~tion of unsaturated polyesters of styrene or other monomers, and cationic curing of vinyl ethers or epoxies. Thus, the dual-cure and hybrid-cure systems can combine radiation curing with thermal curing, or radiation curing with ml)ic~llre curing, for eY~mrle. A combination of E-beam curing with ultraviolet/visible curing is also possible. Combining curing mech~nicm~ can be accompli~hed, for example, by mixing m~teri~ls with two types of functionality on one structure or by mixing dirr~nt m~t~ri~l~ having one type of functionality. Such systems are ~i~cu~secl in Peeters, ~Overview of Dual-Cure and Hybrid-Cure Systems in Radiation Curing,'~ Radiation Curinp in Polymer Science and Technology: Volume III. Polymer Mech~ni~mc, Fouassier and Rabek, eds., Elsevier Applied Science, NY, Chapter 6, 177-217 (1993).
Of the radiation curable m~t~ri~lc, the acrylates are particularly pr~fell~d for use in the binder and tie coat pr~;.~l~or~ of the present invention. FY~mpl~s of such m~t.ori~lc include, but are not limited to, mono- or multi-functional acrylates (i.e., acrylates and methacrylates), acrylated epoxies, acrylated polyesters, acrylated aromatic or aliphatic ureth~ne.s, acrylated acrylics, acrylated silicones, etc., and combinations or blends thereof. These can be monomers or oligomers (i.e., moderately low molecular weight polymers typically conli1inin~
2-100 monomer units, and often 2-20 monomer units) of varying molecular weight (e.g., 100-2000 weight average molecular weight).
A photoinitiator is typically included in ultraviolet/visible curable precursors of the present invention. Illustrative examples of photopolymt-n7~tion initiators (i.e., photoinitiators) include, but are not limited to, organic peroxides, azo compounds, ~uinones, benzophenon~s nitroso compounds, acryl halides, hydrozones, mercapto compounds, pyrylium compounds, triacrylimidazoles, bisimidazoles, chloroalkytriazines, benzoin ethers, benzil ketals, thioxanthones, and acetophenone derivatives, and mixtures thereof Specific examples include benzil,methyl o-benwate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzophenone/tertiary amine, acetophenones such as 2,2-diethoxyacetophenone, benzyl methyl ketal, l-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-CA 02247273 l998-08-24 W O 97/~3719 ~ ~ AUS97/01322 hydroxy-2-methylpropan- 1 -one, 2-benzyl-2-N,N-dimethylamino- 1 -(4-morpholinophenyl)- 1 -butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-methyl- 1 -4(methylthio), phenyl-2-morpholino- 1 -propanone, bis(2,6--limethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, etc. Such 5 photc-initi~tQrs include those available under the trade dçsi~n~tions DAROCUR
4265 (50:50 blend of 2-hydroxy-2-methyl-1-phe~ ,ropall-1-one and 2,4,6-trimethylbenzoyldiphenylphosphine oxide) and CGI1700 (25:75 blend of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine and 2-hydroxy-2-methyl-l-phenylpropan-l-one) available from Ciba-Geigy Corp., Ardsley, NY. The 10 tie coat precursor and binder precursor include a sufficient amount of photoinitiator to provide the line speeds discussed above. Typically, this is within a range ofabout 0.01-5 wt-%, based on the total composition of the precursor.

Abrasive Particles The abrasive particles typically have a particle size in a range of about 0.1-1500 micrometers, and preferably about 0.1-400 micrometers. It is plertlled that the abrasive particles have a MOH's hardness of at least about 8, more prt;rel~bly at least about 9. ~x~mrles of such abrasive particles inclllde7 but are not limited to, fused alumin-lm oxide which in~l~ldes brown ~ minllm oxide, heat treated ~lllminllm oxide and white ~IIlminllm oxide, green silicon carbide, silicon carbide, chromia, ~IIlmin~ zirconia, di~mon~, iron oxide, ceria, cubic boron nitride, gamet, sol-gel abrasive particles, and combinations thereo~
The temm abrasive particles also encompasses agglomerates wherein single abrasive particles are bonded together Abrasive agglomerates are further described in U.S. Patent Nos. 4,311,489 (Kressner), 4,652,275 (Bloecher et al.), and 4,799,939 (Bloecher et al.).
Abrasive particles used in the abrasive articles and/or made according to the present invention can also include a surface coating. Surface coatings are known to improve the adhesion between the abrasive particles and the binder in abrasive articles. They may also improve the abrading properties of the articles. Such surface coatings are, for example, described in U.S. Patent Nos. 5,011,508 WO 97/;~3719 PCT/US97/01322 (Wald et al.), 5,009,675 (Kunz et al.), 4,997,461 (Markhoff-Matheny et al.), 5,213,951 (Celikkaya et al.), 5,085,671 (Martin et al.), and 5,042,991 (Kunz et al.).
Additionally, the abrasive articles may contain a blend of the abrasive particles with diluent particles. These diluent particles can be selected from the group con~isting of: (1) an inorganic particle (nonabrasive inorganic particle); (2 an organic particle; (3) a composite diluent particle co.~ln;ning a mixture of inorganic particles and a binder; (4) a composite diluent particle co~ g a ~f~lule of organic particles and a binder. The nonabrasive inorganic particles typically include materials having a Moh's hardness of less than about 6. The nonabrasive inorganic particles can include grinding aids, fillers, and the like, which are described below. The particle size of these diluent particles can be within a range of about 0.01-1500 micrometers, typically about 1-l000 micrometers. The diluent particles may have the same particle size and particle size distribution as the abrasive particles, or they may be dirrel enl.
Optional Additives for the Binder System The binder precursor and/or tie coat precursor can further include additives, such as, for example, fillers, grinding aids, fibers, lubricants, wetting agents, thixotropic materials, surf~rt~nts, pigments7 dyes, ~nti~t~tic agents, coupling agents, plasticizers, suspending agents, and the like. The amounts of these materials are selected to provide the desired plopellies. The use of these can affect the erodability of the abrasive composite. In some in~t~n~.çs, an additive is purposely added to make the abrasive composite more erodable, thereby expelling dulled abrasive particles and exposing new abrasive particles.
Fillers and grinding aids may be particulate materials. Examples of particulate materials that act as fillers include metal carbonates, silica, silicates, metal sl-lf~tes, metal oxides, and the like. Examples of materials that act as grinding aids include: halide salts such as sodium chloride, potassium chloride, sodium cryolite, and potassium tetrafluoroborate; metals such as tin, lead, bismuth, cobalt, - 30 antimony, iron, and ti~ninm; organic halides such as polyvinyl chloride and tetrachloronaphthalene; sulfur and sulfur compounds; graphite, and the like. A

WO 97/~3719 PCTIUS97/01322 grinding aid is a material that has a significant effect on the chemical and physical processes of abrading, which results in improved p~lro~ ance. In particular, it is believed in the art that the grinding aid will: (1) decrease the friction between the abrasive particles and the workpiece being abraded; (2) prevent the abrasive particle 5 from "capping", (i.e., prevent metal particles from becollfing welded to the tops of the abrasive particles; (3) decrease the interface temperature between the abrasive partides and the w~.k~iece; or (4) decrease the grinding forces. In a coated abrasive article with a make, size, and supersize coat, a grinding aid is typically used in the size or supersize coat applied over the surface of the abrasive particles.
Typically, if desired, a grinding aid is used in an amount of about 5 300 g/m2 of abrasive article.
Fx~mples of anti~t~tic agents include graphite, carbon black, v~n~ium oxide, humectants and the like. These ~nfi~t~tic agents are disclosed in U.S. Patent Nos. 5,061,294 (Harmer et al.), 5,137,542 (Buch~n~n et al.), and ~,203,884 15 (B~lch~n~n et al.).
A coupling agent can provide an association bridge between the binder precursor and the filler particles or abrasive particles. Examples of coupling agents include silanes, titanates, and zircoalllmin~tes The abrasive slurry preîtl ablyincludes about 0.01-3% by weight coupling agent. There are various means to 20 incorporate the coupling agent. For example, the coupling agent may be added directly to the binder precursor. Alternatively, the coupling agent may be applied to the surface of the filler particles. In still another means, the coupling agent is applied to the surface of the abrasive particles prior to being incorporated into the abrasive article.
2~
Methods of Making the Abrasive Articles The abrasive articles of the invention are prepared by coating the backing with the tie coat precursor at a coating weight of about 4-117 g/m2, pl~felably about 12-63 g/m2, and more preferably about 16-34 g/m2. The tie coat precursor 30 can be applied by a variety of methods, such as knife coating, die coating, gravure coating, squeeze roll coating, spray coating, curtain coating, and other methods that WO 97/~3719 PCTIUS97/01322 can uniformly apply at least a monomolecular layer to the substrate. The abrasive slurry can then be applied to this tie coated-bac~ing by a variety of methods, such as roll co~tin~ gravure coating, knife coating~ spray co~tin~ transfer coatin~ vacuum die coating~ die coating, and the like, or the tie-coated bar,king can be brought into contact with the abrasive slurry in a mold having the inverse of the desired topography.
The tie coat precursor can be at least partially cured prior to application of the abrasive s1urry. Alternatively, the tie coat precursor can be at least partially cured at the same time that the binder precursor of the abrasive slurry is at least partially cured. The term 'partial cure" means that the resin is polymerized and/or crosslinked to such a state that the slurry does not flow from an inverted test tube.
For structured abrasive articles, partial cure of the resin at the int~ ce between the resin and the tooling is important to allow removal of the tooling. Partial cure is accomplished by adjusting the dosage and radiation, as is commonly done by one of skill in the art. If further cure is desired, the resin can then be further cured with time and/or exposure to another energy source, such as a thermal energy source.
Suitable energy sources for use in the curing steps of the invention include therrnal energy, electron beam, ultraviolet light, visible light, or combinalions thereo~ Preferably, radiation energy is used, and more preferably W/visible light is used. Electron beam radiation, which is also known as ionizing radiation, can beused at an energy level of about 0.1 Mrad to about 10 Mrad, and at an accelerating voltage level of about 75 Kev to about 5 mev, preferably at an accelerating voltage level of about 250 Kev to about 300 Kev. Ultraviolet radiation refers to nonparticulate radiation having a wavelength within the range of about 200 nanometers to about 400 nanometers. It is preferred that 118-236 watts/cm ultraviolet lights are used. Visible radiation refers to nonparticulate radiation having a wavelength within the range of about 400 nanometers to about 800 nanometers.
The rate of curing depends on the degree of cure desired, the thickness of the abrasive slurry and tie coat precursor layers (i.e., coating weights), as well as the compositions of these layers. Although some abrasive particles and/or optional additives may absorb the radiation energy to inhibit curing of the binder precursor wo 97/~3719 PCT/US97/01322 and tie coat precursor, higher doses of radiation energy can be employed to the extent needed to compensate for such radiation absorbance. Significantly, however, the abrasive articles are sl~fficiently cured within seconds, and even fractions of a second. This is particularly unexpected because of the thickness of the abrasive5 slurry layer and tie coat precursor layer, which can be about 0.076 cm.
Additionally, after the abrasive articles are cured by radiation energy, they can be post-cured by therrnal energy. Generally, this does not provide advantage to thecuring of the binder precursor or tie coat precursor, but can provide advantage for some conventional cloth treatmPnt coats.
Pl~elled methods of making conventional structured abrasive articles are described in U.S. Patent No. 5,436,816 (Spurgeon et al.). One method involves:
(1) introducing the abrasive slurry (abrasive particles and binder precursor) onto a cont~ctinE surface of a production tool, ~l~erehl the production tool has a cont~cting surface with a specified topography or pattern; (2) introducing a 15 tie-coated backing to the contacting surface of the production tool such that the slurry wets the front surface (i.e., the first major surface) of the tie-coated backing to form an interrne-liate article; (3) at least partially curing the binder precursor and tie coat precursor before the intermediate article departs from the cont~cting surface of the production tool to form a shaped, h~ntlle~ble structure; and (4) 20 removing the shaped, h~n~leable structure with the b~r.~ing thereon (i.e., the structured abrasive article) from the production tool.
Another method involves: (1) introducing the abrasive slurry onto the tie-coated backing such that the abrasive slurry wets the front side (i.e., the first major surface) of the bar~ing to form an interrne~i~te article; (2) introducing the 25 interrnediate article to the contacting surface of a production tool under a sufficient force to cause the abrasive slurry to assume the shape (i.e., the topography or pattern) of the contacting surface of the production tool; (3) at least partially curing the binder precursor and tie coat precursor before the intermediate article departs from the contacting surface of the production tool to form a shaped, handleable 30 structure; and (4) removing the shaped, handleable structure with the backingthereon (i.e., the structured abrasive article) from the production tool. These W O 97/~3719 PCT~US97/01322 methods can be batch processes or continuous processes, preferably, however, they are continuous processes. If a continuous process is used, the~ tie coat precursor can be applied and at least partially cured in line.
If the production tool is made from a transparent material (e.g., a 5 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 binder precursor. This is further described in U.S. Patent No. 5,435,816 (Spurgeon et al.). Alternatively, if the abrasive backing is l~ansparen~ to visible or ultraviolet light, visible or ultraviolet light can be l~n~ ed through the abrasive bacl~inp. ~lefelably, the production tool is radiation tr~n.~mi~.~ive and allowsradiation energy, particularly ultraviolet/visible light, to be tr~n.cmitted therethrough.
The resulting solidifed abrasive slurry (i.e., the shaped, handleable structure or the abrasive composite) has the inverse pattern of the production tool. By atleast partially curing or solidifying on the production tool, the abrasive composite has a precise and predetermined pattern. The binder can be further solidified orcured offthe production tool.
A production tool having a plurality of precisely shaped cavities is used to make the structured abrasive article. These cavities are ec~enti~lly the inverse shape of the abrasive composites and are responsible for generating the shape of the abrasive composites. The dimensions of the cavities are selected to provide the desired shape and dimensions of the abrasive composites.
The production tool can be a belt, a sheet, a continuous sheet or web, a coating roll such as a rotogravure roll, a sleeve mounted on a coating roll, or a die.
The production tool can be composed of metal, (e.g., nickel), metal alloys, or plastic. The metal production tool can be fabricated by any conventional technique such as engraving, hobbing, electroforming, etching, diamond turning, and the like.
One prere,led technique for a metal production tool is diamond turning. It is preferably a thermoplastic production tool made from polypropylene as disclosed in U.S. Patent No. 5,436,816 (Spurgeon et al.). The production tool may also contain a release coating to permit easier release of the abrasive composites from the WO 97t~3719 PCTIUS97/01322 production tooE, such as silicones and fluorochemicals, as disclosed in U.S. Patent No. 5,436,816 (Spurgeon et ai.).

EXAMPLES
The follo~,ving nonlimiting c;"~nplcs will further illustrate the invention. Allpartis, percentages, ratios, etc., are by weight unless otherwise specified. Thefollowing desi~n~tions are used throughout the cxamples.

WAO white fused ~hlminllm oxide abrasive grain, co"lmelcially available under the trade design~tion BZK-B from H.C. Stark Co., Laufenberg, Germany;

MSCA gamma-m~th~rryloxypropyll~ lellloxysilane~ known under the trade design~tion A-174, commercially available from O~i Specialties, Inc., Danbury, CT;

KBF4 potassium tetrafluoroborate, commercially available from Atotech USA, Inc., Cleveland, OH;

ASP amorphous silica particles having an average surface area of 50 m2/g,and average particle size of 40 millimicrometers, commercially available under the trade design~tion OX-50 from Degussa Corp., Ridgefield Park, NJ;

25 TATHEIC triacrylate of tris(hydroxy ethyl) isocyanurate, co".l"ercially available under the trade design~tion SARTOMER 368 from Sartomer, Exton, PA;

TMPTA trimethyolpropane triacrylate, commercially available under the trade deci~n~tion SARTOMER 351 from Sartomer, Exton, PA;

WO 97/~371g PCT/US97101322 PH2 2-benzyl-2-N,N-dimethylamino- 1 -(4-morpholinophenyl)- 1 -butanone, commercially available under the trade de~ien~tion IRGACURE 369 from Ciba-Geigy Corp., Hawthorne, NY;

S BTR Brown ~ mimlm oxide abrasive particles, com,l,ercially available from USEM, U.S. Electrofused Mineral, Inc., Raltimnre, M:D; and GW Green silicon carbide abrasive particles, CCSIIllll~,. cially available under the trade dçcign~tion CARB GW from Exolon-ESK
Company, Tonawanda, NY.

General Procedure for Making Structured Abrasive Articles The abrasive articles employing slurries of the invention were made generally in accordance with U.S. Patent No. 5,436,816 (Spurgeon et al.), with the addition of a tie coat precursor. First, a tie coat precursor was applied to the front surface of the cloth backing. Then, an abrasive slurry composition was prepared by thoroughly mixing abrasive particles with a binder precursor consisting of 39.55%
TMPTA, 16.95% TATHEIC, 0.56% PH2, 1.98% ASP, 1.98% MSCA, and 38.98%
KBF4. The slurry used in each case was coated onto a po}ypropylene production tool with a 0.036 cm high vari-pitch pattern having a pyramidal type pattern such that the slurry filled the tool. The pyramids were placed such that their bases were butted up against one another. The width of the pyramid base was about 530 micrometers and the pyrarnid height was about 353 micrometers. This pattern is illustrated in Figure 1 of PCT Application No. WO 95/07797 (Hoopman).
Next, the tie coated-cloth was pressed against the production tool by means of a nip roll so that the slurry wetted the front surface (i.e., the tie-coated surface) of the cloth. Ultraviolet/visible light was concurrently tr~n.cmitted through the polypropylene tool and into the abrasive slurry cont~inin~ the binder precursor.The ultraviolet/visible light initi~ted the polymerization of the radiation curable resin of the binder precursor, resulting in the abrasive slurry being transformed into an abrasive composite, with the abrasive composite being adhered to the cloth backing.

WO g7/~3719 ' rCT/US97/01322 The ultraviolet/visible light sources used were two bulbs known under the trade desi~n~tion Fusion Systems D bulbs, which operated at 236 wattslcm of bulb width.
Finally, the cloth/abrasive composite was separated from the polypropylene production tool, providing a coated abrasive article.

Test Procedures The following test procedures were used to test structured abrasive articles made according to the examples.

10 90~ Peel Test In order to measure the degree of adhesion of the structured abrasive layer to the bacl~ing, the sheet to be tested was converted into a sample about 8 cm wide by 25 cm long. One-half the length of a wooden board (17.78 cm by 7.62 cm by 0.64 cm thick) was coated with an adhesive. The entire width of, but only the first 15 15 cm of the length of, the coated abrasive sample was coated with an adhesive on the side bearing the abrasive material. The adhesive was 3M Jet Melt Adhesive #3779, which is commercially available from 3M Coll~pally, St. Paul, MN, appliedwith a Polygun II. Then, the side of the sample bearing the abrasive material was at1~checl to the side of the board col-t~ ;n~ the adhesive coating in such a manner 20 that the 10 cm of the abrasive sample not bearing the adhesive overhung from the board. Pressure was applied such that the board and the sample were intim~t~ly bonded, and sufficient time was allowed for the adhesive to cool and solidify.
Next, the sample to be tested was scored along a straight line such that the width of the coated abrasive test specimen was reduced to 5.1 cm. The resulting 25 abrasive sample/board composite was mounted horizontally in a fixture attached to the upper jaw of a tensile testing machine having the trade decign~tion SINTECH,and approximately 1 cm of the overh~nging portion of the abrasive sample was mounted into the lower jaw of the machine such that the distance between jaws was 12.7 cm. The mac.hine separated the jaws at a rate of 0.5 cm/second, with the 30 coated abrasive sample being pulled at an angle of 90~ away from the wooden board so that a portion of the sample separated from the board. Separation occurred WO 97/~3719 PCT/US97tO1322 between layers of the abrasive construction. The machine charted the force per c~ ;,..cter of ~.er; ~..,n width required for separation. The higher the required force, the better the shelling resistance of the abrasive construction.
Some of the articles of the ~Y~mples were tested for 90~ peel adhesion. The 5 force required for separation was ~Al,ressed in kg/cm. The results are set forth in Tables 1-7, and are presented as an average of two test specimens. It is plefe-led that the force value be at least 1.8 kg/cm, more preferably at least 2 kg/cm, because inadequate adhesion and we~kn~ss at the structured abrasive layer-cloth interface will generally results in inferior performance particularly under dynamic conditions.

Rocker Drum Test Unflexed structured abrasive articles were converted into 10.2 cm by 15.2 cm sheets. These samples were installed on a cylindrical steel drum of a testing machine which oscillates (rocks) back and forth in a small arc creating a 1.3-cm by 10.1 cm wear path. The structured abrasive abraded the stationary 1.3 cm by 1.3 cm by 15.2 cm Type 1018 carbon steel wolh~icce. There were applox;,-.~t~ly 60 strokes per minute on this wear path The load applied to the workpiece via a lever arm was 3.6 Kg. The total arnount of carbon steel removed after 500 cycles (i.e., one cycle being one back-and-forth motion) was recorded as 20 the total cut. The results are reported in the tables below as an average of four test specimens. This is referred to herein as a Rocker Drum Test.

Examples Structured abrasive articles were made using either Type J or Type X
25 backings. Type J backing was a cellulosic cloth backing having a blend of an acrylic latex/resole phenolic resin (85 parts acrylic latex and 15 parts phenolic) presize.
Type X backing was a poly/cotton (blend of polyester and cotton) cloth backing having a b}end of an acrylic latex/resole phenolic resin (85 parts acrylic latex and 15 parts phenolic) presize, and a nitrile latex/resole phenolic resin (40 parts latex and 30 60 parts phenolic) backfill.

WO 97/~371g rCTlUS97101322 Fx~mples 1-4 For the data listed in Table 1, the tie coat precursor (No.~ 1) was a 70/30/1 blend of TMPTA, TATIIEIC, and PH2 resin coated by a 3 roll sq~lee7e method. It was at least partially cured using an ultraviolet/visible light source of one bulb under 5 the trade ~e~ign~tion Fusion System D Bulb operated at 157 watts/cm of bulb width, and a line speed of 45.7 meters/minute. The abrasive slurry (No. 1) included 58.9% grade P-320 WAO and 41.1% binder precursor as described above in the General Procedure for Making Structured Abrasive Articles.

Table 1 Abrasive Tie Coat Adhesion ExampleLine Speed Slurly Precursor Force Backing No.(meters/minute) No. No. (Kg/cm) Type J 1 30.5 1 1 2.47 Type J 2 30.5 1 1 2.49 Type J 3 30.5 1 1 2.34 Type J 4 30.5 1 none 1.65 This data shows the reproducibility of three individual rolls coated with the tie coat and processed as ~ cl~sed above. It also signifies the signific~nt improvement in adhesion with the use of the tie coat.
Examples 5- 13 For the data listed in Table 2, the tie coat precursor (No. 2) was 70/30/1 blend of TMPTA, TATHEIC, and PH2 resin coated in-line with a knife over bed method using a 0.003 cm gap onto the backing. The tie coat precursor was not 20 precured before the abrasive slurry was applied and cured. The tie coat precursor (No. 3) was 70130/1 blend of TMPTA, TATHEIC, and PH2 resin coated in-line with a knife over web method using a 0.003 cm gap onto the backing. The tie coatprecursor was not precured before the abrasive slurry was applied and the binderprecursor contained therein was at least partially cured.

wO 97/33719 PCT/US97/01322 Table 2 Line Speed Abrasive Tie Coat Adhesion Rocker Ex. (meters/ Slurry Precursor Force Drum Cut Backing No. minute) No. No. (Kg/cm) (~rams) Type J 5 15.2 1 2 2.19 ntl Type J 6 22.9 1 2 2.10 0.27 Type J 7 30.5 1 2 2.01 0.27 Type J 8 15.2 1 3 2.25 nt Type J 9 30.5 1 3 1.77 0.34 Type J 10 45.7 1 3 1.51 nt Type J 11 15.2 1 none 1.48 nt Type J 12 30.5 1 none 1.65 nt Type J 13 45.7 1 none 1.08-1.612 0.28~0.032 1nt = not tested.
2This represents a number of tests, therefore a range is presçnted This data jnrlic~tes that having back-up support, provided by the knife over bed coating method, when the tie coat precursor is applied is benefici~l in m~int~ining high adhesion values as run speed is increased. It also demon~l,atesthat the tie coat precursor does not need to be cured prior to application of the abrasive slurry.
Examples 14- 17 For the data in Table 3, the abrasive slurry ~o. 2) in~ ded 49% binder precursor and 51% GW grade F-400, the slurry (No. 3) included 46% binder precursor and 54% GW grade F180 The tie coat (No. 4) was coated with the 3 roll squeeze method and 50/50/1 TMPTA, TATHEIC, and PH2 resin.

wo 97/~3719 PCT/US97/01322 Table 3 Line Speed Abrasive TieCoatAdheslon. Rocker Ex. (meterst Slurry PrecursorForce Drum Cut Backing No. minute) No. No. (Kg/cm) (grams) Type J 14 15.2 2 none 0.67 0.08 Type J 15 15.2 2 4 1.04 0.08 Type J 16 15.2 3 none 0.79 0.30 TypeJ 17 22.8 3 4 1.56 0.31 For structured abrasive constructions using GW, the minim~lm acceptable adhesion force for most applications is 0.90 Kg/cm. Use of the tie coat results in 5 acceptable adhesion values at these line speeds.

F.Y~mples 18-29 For the data in Table 4, the abrasive slurries (No. 4) in~l~lded 40.8% binder precursor and 59.2% grade F180 BTR, (No. 5) in~luded 42.62% binder precursor and 57.38% grade F240 BTR, (No. 6) in~.hlded 43% binder precusor and 57%
grade F220 BTR, and (No. 7) inr.hlded 48% binder precursor and 52% grade F360 BTR. The tie coat precursors (Nos.1 and 4) were coated as described above.

wo 97/~3719 PCT/USg7/01322 Table 4 Line Speed Abrasive Tie Coat Adhesion Rocker Ex. (meters/ Slurry Precursor Force Drum Cut Backing No. minute) No. No. (Kg/cm) (grams) Type J 18 30.5 4 none 1.22 0.24 Type J 19 30.5 4 1 2.01 0.36 Type J 20 45.7 4 1 1.99 0.38 Type J 21 76.2 4 4 1.79 0.33 Type J 22 30.5 5 none 1.54 0.26 Type J 23 30.5 5 4 2.19 nt Type J 24 45.7 5 4 2.06 nt Type J 25 30.5 6 none 1.51 0.34 Type J 26 45.7 6 none 1.24 nt Type X 27 30.5 7 none 1.78 0.08 Type X 28 30.5 7 4 2.05 0.09 Type X 29 45 7 7 4 2.12 0.09 nt = Not tested.

This data shows that the tie coat improves adhesion over a broad range of 5 mineral sizes and line speeds. To verify these tests, belts were tested in an actual customer-type application involving the grinding of tit~nil-m-based golf clubs.
Examples 23 and 24 with tie coat showed 25~/n improvement in the number of partsground and ran more evenly from start to finish co~ ,ared to Example 22 belts that did not have the tie coat for grinding the shaped portions of tit~nillm-based golf 10 clubs. The belts from Exarnples 23 and 24 had much less shelling of the abrasive from the backing compared to Example 22 belt, which indicates that the adhesion of the structured abrasive layer to the b~c~ing is improved during actual use of the belt. This substantial improvement in grinding pelrol,llance and life was an unexpected result of having the tie coat in the construction.

W O 97/~3719 PCTAUS97/01322 Examples 30-41 For the data listed in Table 5, the tie coat precursors and abrasive slurries are as listed above. Certain of the sarnples were post cured at 116~C for 12 hours.

Table 5 Line Speed Abrasive TieCoat Adhesion Ex.(meters/ Slurry Precursor Force Post Backing No.minute) No. No. (Kg/cm) Cured Type X 30 45.7 5 4 2.75 yes Type X 31 45.7 5 4 2.7 no Type J 32 45.7 5 4 2.5 yes Type J 33 45.7 5 4 2.29 no Type J 34 15.2 5 1 2.56 yes Type J 35 15.2 5 1 2.44 no Type J 36 30.5 5 1 2.37 yes Type J 37 30.5 5 1 2.41 no Type J 38 45.7 5 1 2.28 yes Type J 39 45.7 5 1 2.11 no Type J 40 61 5 1 1.75 yes Type J 41 61 5 1 1.34 no The data in Table 5 shows that thermal post-curing generally has little effect on adhesion, although thermal post-cure is desirable for curing the backfill co~tin which was on the Type X cloth backing only.
Examples 42-54 For the data listed in Table 6, the tie coat presursor (No. 5) was the same as tie coat precursor (No. 1) except only 0.16 part of PH2 was used. Tie coat precursor (No. 6) was the same as tie coat precursor (No. 1) except only 0.25 part 15 of PH2 was used. Tie coat precursor (No. 7) was the same as tie coat precursor (No. 1) except only 0.5 part of PH2 was used. Tie coat precursor (No. 8) was the W O 97/~3719 PCT~US97~1322 same as tie coat precursor (No. 1) except only 0.75 part of PH2 was used. All were coated and cured in the same manner as was tie coat precursor (No. 1).
F.~mrles 42-54 were prepared by coating the tie coat precursor onto the bar~ing (3.14 cm by 4.72 cm) using a number 24 wire wound rod to spread a 5 uniforrn layer of l.~ resin over the backing. The coated b~c~ing was curedby taping the sample to a metal tray and passing under a Fusion D bulb at 236 watts/cm at the listed line speed and environmçnt~l condition. The treated salll~ s were coated with the structured abrasive slurry with the same method as in Example 1 with the following change. The cloth s~mples, 3.14 cm by 4.72 cm were taped to a 0.008 cm polyethylene terephth~l~te (PET) film that was 3.94 cm wide and the line was run at 15.2 meters/minute.

Table 6 Tie Coat Tie Coat Cure Speed Adhesion Ex.TieCoat Cure (meters/ Slurry Force Backing No.TreatmentEnviron't minute) No. (Kg/cm) Type J 42 4 air 30.5 5 2.01 Type J 43 4 nitrogen 30.5 5 .1.99 Type J 44 4 air 61 5 1.97 Type J 45 4 nitrogen 61 5 2.01 Type J 46 1 air 30.5 5 1.94 Type J 47 1 nitrogen 30.5 5 2.02 Type J 48 1 air 61 5 1.83 Type J 49 1 nitrogen 61 5 2.01 Type J 50 none ~ -- 5 1.66 Type J 51 5 air 30.5 5 1.74 Type J 52 6 air 30.5 5 1.88 Type J 53 7 air 30.5 5 1.97 Type J 54 8 air 30.5 5 2.02 WO 97/~3719 PCT/US97/01322 These results indicate that the adhesion force of the cured structure abrasive slurry to the backing indicates that the run speed studied and the environlllGI.~ under which the tie coat was cured did not effect the reslllting adhesion. The photoinitiator conce.,ll~lion used to cure the tie coat to the backing has an effect on 5 the adhesion of the structured abrasive to the backing being best at concentrations above 0.25 part of the resin system studied.

Examples 55-56 For the data listed in Table 7, no lle~l~..e!~ coat(s) (e.g., presize or backfill 10 coats) were used on the cloth baç~ing~. The tie coat precursor (No. 4) and the abrasive slurry (No. 1) are described above.

Table 7 Adhesion Ex. Line Speed Slurry Force Backing No.Tie Coat(meters/minute) No. (Kg/cm) Type X 55 none 15.9 1 <0.36 (untreated) Type X 56 4 15.9 1 1.47 (untreated) This example shows that a tie coat produces enhanced adhesion values, even when no cloth treatment is present.

Claims (10)

1. A method of preparing an abrasive article, the method comprising (a) coating a first major surface of a backing with a tie coat precursor, wherein the tie coat precursor comprises a first radiation curable component;
   (b) applying an abrasive slurry to the first major surface of the backing after coating the tie coat precursor thereon, wherein the abrasive slurry comprises a plurality of abrasive particles and a binder precursor, and further wherein the binder precursor comprises a second radiation curable component;
   (c) at least partially curing the tie coat precursor; and (d) at least partially curing the binder precursor to form an abrasive article.
2. 2. The method of claim 1 wherein the step of at least partially curing the tie coat precursor occurs prior to the step of applying an abrasive slurry to the first major surface of the backing or wherein the steps of at least partially curing the tie coat precursor and at least partially curing the binder precursor occur substantially simultaneously.
3. 3 The method of claim 1 wherein the steps of at least partially curing the tie coat precursor and at least partially curing the binder precursor comprise exposing both the tie coat precursor and binder precursor to radiation energy
4. 4 The method of claim 1 wherein:
   (a) the step of applying the abrasive slurry to the backing comprises:
   (i) applying the abrasive slurry onto a contacting surface of the production tool; and (ii) contacting the abrasive slurry on the contacting surface of the production tool with the first major surface of the backing; and (b) the step of at least partially curing the binder precursor to form an abrasive article comprises:
   (i) at least partially curing the binder precursor to form a shaped, handleable structure; and (ii) separating the shaped, handleable structure from the production tool to form an abrasive article.
5. 5. A method of claim 4 wherein the production tool is a radiation energy transmissive production tool.
6. 6. The method of claims 1-5 wherein the tie coat precursor and binder precursor each further comprise a photoinitiator.
7. 7. The method of claims 1-6 wherein the tie coat precursor and the binder precursor are acrylate-functional compounds.
8. 8. An abrasive article made by the methods of claims 1-7.
9. 9. An abrasive article comprising:
   (a) a cloth backing having a first major surface;
   (b) a radiation cured tie coat on the first major surface of the backing; and (c) an abrasive layer on the radiation cured tie coat, wherein the abrasive layer comprises a plurality of abrasive particles dispersed in a radiation cured binder.
10. 10. The article of claims 8 and 9 which is a structured abrasive article.