CA2264872A1 - Abrasive article and method of making - Google Patents

Abstract

This invention pertains to an abrasive article comprising preci sely shaped particles. The abrasive article may be a coated abrasive article, a bonded abrasive or a nonwoven abrasive article. The precisely shaped particles may further comprise abrasive grits, fillers, grinding aids and lubricants. The precisely shaped particles can be made according to the following method: (a) providing a production tool having a three-dimensional body which has at least one continuous surface, said surface containing at least one opening formed in said continuous surface, said at least one opening providing access to a cavity in said three-dimensional body; (b) providing a dispensing means capable of introducing a binder precursor comprising a thermosetting resin into said at least one cavity through said at least one opening; (c) providing a means, within a curing zone, for at least partially curing said binder precursor; (d) introducing said binder precursor into at least a portion of said at least one cavity; (e) continuously moving said at least one cavity through said curing zone to at least partially cure said binder precursor to provide a solidified, handleable binder having a shape corresponding to that portion of the cavity into which the binder precursor has been introduced; (f) removing said binder from said at least one cavity; and (g) converting said binder to form a precisely shaped particle. Steps (f) and (g) may be conducted simultaneously. The particles can be bonded together to form a shaped mass, e.g., a wheel; alternatively, the particles can be bonded to a backing to form a coated abrasive article; or the particles can be bonded into a fibrous, nonwoven substrate to form a non-woven abrasive article.

Description

CA 02264872 1999-02-23WO 98/10896 PCT/US96ll4570ABRASIVE ARTICLE AND METHOD OF MAKINGBACKGROUND OF THE INVENTION5 1. Field of the Inventionl0152025This invention relates to particulate material comprising a binder, and amethod for making same. When the particulate material further contains abrasivegrits, it can be used in bonded abrasives, coated abrasives, and nonwoven abrasives.2. Discussion ofthe ArtConventional coated abrasive articles typically consist of a layer of abrasivegrits adhered to a backing. Generally only a small fraction of the abrasive grits inthis layer are actually utilized during the useful life of the coated abrasive article. Alarge proportion of the abrasive grits in this layer are wasted. Furthermore, thebacking, one of the more expensive components of the coated abrasive article, mustalso be disposed of before it has worn out.Many attempts have been made to distribute the abrasive grits on thebacking in such a manner so that a higher percentage of abrasive grits are actuallyutilized, thereby extending the useful life of the coated abrasive article. Byextending the life of the coated abrasive article, fewer belt or disc changes arerequired, thereby saving time and reducing labor costs. Merely depositing a thicklayer of abrasive grits on the backing will not solve the problem, because grits lyingbelow the topmost grits are not likely to beiused.Several methods whereby abrasive grits can be distributed in a coatedabrasive article in such a way as to prolong the life of the article are known. Onesuch way involves incorporating abrasive agglomerates in the coated abrasivearticle. Abrasive agglomerates consist of abrasive grits bonded together by meansof a binder to form a mass. The use of abrasive agglomerates having randomshapes and sizes makes it difficult to predictably control the quantity of abrasive-1-W0 98/10896l015202530CA 02264872 1999-02-23PCT/US96/14570grits that come into contact with the surface of a workpiece. For this reason, itwould be desirable to have an economical way to prepare precisely shaped abrasiveagglomerates.SUMMARY OF THE INVENTIONThis invention provides precisely shaped particles and methods for makingthese particles. The particles comprise a binder. In one desirable embodiment, aplurality of abrasive grits is dispersed in the binder.The method of this invention comprises the steps of:(a) providing a production tool having a three—dimensional body whichhas at least one continuous surface, the surface containing at least one openingformed in the continuous surface, with at least one opening providing access to acavity in the three—dimensional body;(b) providing a dispensing means capable of introducing a binderprecursor comprising a thermosetting resin into said at least one cavity through saidat least one opening;(c) providing a means, within a curing zone, for at least partially curingsaid binder precursor;(d) introducing said binder precursor into at least a portion of said atleast one cavity;(e) continuously moving said at least one cavity through said curingzone to at least partially cure said binder precursor to provide a solidified,handleable binder having a shape corresponding to that portion of the cavity intowhich the binder precursor had been introduced; .(t) removing said binder from said at least one cavity; and(g) converting said binder to form a precisely shaped particle.Steps (f) and (g) can be conducted simultaneously.In a preferred embodiment, a plurality of abrasive grits is included with thebinder precursor in step (d), and a binder containing abrasive grits is formed in step(e). The binder that contains abrasive grits is removed from the at least one cavityW0 98/10896IO15202530CA 02264872 1999-02-23PCT/U S96l 14570of the production tool in step (0. Materials other than abrasive grits can beincluded with the binder precursor.The curing zone can contain a source of thermal energy, a source ofradiation energy, or both. Suitable sources of radiation energy include electronbeam, visible light, and ultraviolet light. In a variation of the general method, curingcan be effected by thermal energy or by a combination of radiation energy andthermal energy.In both the general and preferred embodiments, it is preferred that steps ((1),(e), and (f) be carried out on a continuous basis or be carried out in a continuousmanner. For these embodiments, it is preferred that the production tool be anendless web (belt), or a drum, preferably .a cylindrical drum, which will rotate aboutits axis. Alternatively, a web having two ends can be used. Such a two-ended webtravels from an unwind station to a rewind station.production tool have a plurality of cavities.During step (e) of the method, the binder precursor is solidified so as to beconverted into a handleable binder.The binder can be converted into particles by several means. In one means,when the binder is removed from the cavities of the production tool, it is released inthe form of individual particles. These particles can contain additional materials orbe free of additional materials. A typical material that can be included in theseparticles is abrasive grits. The resulting particles preferably have shapes that areessentially the same as the shapes of the cavities of the production tool. Thus, theparticles have shapes that are determined by the shapes of the cavities of theproduction tool. In this first means, steps (0 and (g) are accomplishedsimultaneously, because the shaped particles have their characteristic form whenthey are released from the cavities of the production tool.In a second means, the binder is removed from the major surface of theproduction tool in the form of a sheet comprising shaped portions that are ofessentially of the same size and shape of the cavities of the production tool, butjoined together by a relatively thin connecting layer of the material of the binder. Inthis second means, the sheet is then broken or crushed along the thin connecting'3-3-It is preferred that the‘W0 98/1089610I5202530CA 02264872 1999-02-23PCT/US96/14570layer of binder material to form the particulate material of this invention. Theparticles can be screened or classified to remove any undesired particles. If theconnecting layer of the binder material is carefully broken or crushed, the resultingparticles can have shapes that are essentially the same as those of the cavities of theproduction tool.It is also within the scope of this invention to use a carrier web to deliverbinder precursor to the production tool. The binder precursor can be coated ontoone major surface, e.g., the front surface, of a carrier web and then the resultingcoated carrier web is brought into contact with the continuous surface of theproduction tool that contains the cavities. After at least partial curing, i.e.,solidifying, of the binder precursor in the production tool, the binder, whichpreferentially adheres to the surface of the carrier web, is removed first from theproduction tool and then from the carrier web. Alternatively, the binder precursoris coated onto the continuous surface of the production tool having cavities,whereby such cavities are filled, and the carrier web is brought into contact with thecontinuous surface of the production tool containing the binder precursor in such amanner that the binder precursor contained in the cavities contacts the surface ofthe carrier web. After at least partial curing, i.e., solidifying, of the binderprecursor, the binder adheres to the surface carrier web rather than to theproduction tool. The binder can then be removed from the carrier web.Subsequently, the precisely shaped particles are formed.The precisely shaped particles can be modified by means of additives for usein abrading applications, either by themselves or as a component of an abrasivearticle. The particles of this invention can be used to prepare abrasive articlescomprising a plurality of shaped particles, each of which comprises at least oneabrasive grit and a binder, in which the binder is formed from a binder precursorcomprising a thermosetting resin that can be cured by radiation energy or thermalenergy or both. The particles can be bonded together to form a shaped mass, e.g., awheel; alternatively, the particles can be bonded to a backing to form a coatedabrasive article; or the particles can be bonded into a fibrous, nonwoven substrate toform a non-woven abrasive article.W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/ 14570This invention makes it possible to design particles suitable for specificapplications by varying the shape and composition ofthe particles. The process ofthis invention provides a simple, fast, and economical method for manufacturingparticles, especially abrasive particles having a precise shape. The process of thisinvention makes it possible to accurately make abrasive particles having the samedimensions from batch to batch, thereby leading to more consistent abrasivearticles.Another aspect of the invention pertains to a coated abrasive article,comprising:(a) a backing having a front and back surface;(b) _ a make coat present on the front surface of the backing;(c) an abrasive layer bonded to the front surface of the backing bymeans ofthe make coat, wherein the abrasive layer comprises:(1) a plurality of abrasive grits;(2) a plurality of precisely shaped grinding aid particles , whereinthe precisely shaped grinding aid particles comprise a binder and a plurality ofgrinding aid particulates; and(d) a size coat present over the abrasive layer.In general, it is preferred that the surface area of the abrasive layercomprises 5 to 90 percent, preferably l0 to 75 percent, most preferably 20 to 40percent precisely shaped grinding aid particles.Another aspect of the invention pertains to a bonded abrasive article,comprising:(a) a bonding medium;(b) a plurality of abrasive grits;(c) a plurality of precisely shaped grinding aid particles, wherein theprecisely shaped grinding aid particles comprise a binder and a plurality of grindingaid particulates; and wherein the bonding medium serves to bond the abrasive gritsand precisely shaped grinding aid particles together to form a shaped mass.It is preferred that the bonded abrasive is in the form of a wheel, including acut off wheel. In general, the volume percent of the precisely shaped grinding aid-5-W0 98l108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570particles in a bonded abrasive ranges from about 5 to 85 percent, preferablybetween 5 to 75 percent, more preferably between 5 to 60 percent and mostpreferably between 10 to 60 percent. ‘The precisely shaped grinding aid particles may further comprise abrasivegrits. The abrasive grits will generally have a Moh hardness greater than about 8.However, it is generally preferred that the precisely shaped grinding aid particlesconsist essentially ofthe binder and grinding aid particulates.Still another aspect of the invention pertains to a precisely shaped abrasiveparticle, comprising:(a) a binder, wherein the binder is formed from a binder precursorcomprising a resole phenolic resin and a free radically curable resin;(b) a plurality of abrasive grits distributed in the binder to form theprecisely shaped abrasive particle.This type of precisely shaped abrasive particle can be incorporated into acoated abrasive article, a bonded abrasive article or a nonwoven abrasive article.A further aspect of the invention pertains to an abrasive article comprising:(a) a bonding medium, wherein the bonding medium having a pluralityof precisely shaped filler particles distributed in a cured resinous adhesive, whereinthe precisely shaped filler particles comprise a plurality of filler particles distributedin a binder;(b) a plurality of abrasive grits,wherein the bonding medium serves at least one of the following fiinctions:(1) to bond the abrasive grits to a backing;(2) to bond the abrasive grits into and onto a nonwovensubstrate; and(3) to bond the abrasive grits together to form a shaped mass.Another perspective of the invention pertains to a coated abrasive article,comprising:(a) a backing having a front and back surface;(b) a make coat present on the front surface of the backing:W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96Il4'570(c) a plurality of abrasive grits bonded to the front surface of thebacking by means of the make coat; and(d) a size coat present over the abrasive grits, wherein at least one of themake or size coats comprises a plurality of precisely shaped filler particlesdistributed in a cured resinous adhesive, wherein the precisely shaped filler particlescomprise a plurality of filler particles distributedin a binder.BRIEF DESCRIPTION OF THE DRAWINGSFIGS. 1, 2, and 3 are schematic side views illustrating various methods ofcarrying out the process ofthis invention.FIGS. 4 and 5 are schematic side views in elevation of a coated abrasivearticle that utilizes the particles ofthis invention.FIG. 6 is a perspective view of a segment of the production tool ofFIG. l.The segment illustrated in FIG. 6 is substantially similar to segments of theproduction tools ofFlGS. l, 2, and 3.FIGS. 7 and 8 are schematic side views illustrating other methods ofcarrying out the process ofthis invention.DETAILED DESCRIPTION OF THE INVENTIONAs used herein, the expression "binder precursor" means any material that isconformable or can be made to be conformable by heat or pressure or both and thatcan be rendered non—conformable by means of radiation energy or thermal energy orboth. As used herein, the expression "solidified, handleable binder" means a binderprecursor that has been polymerized or cured to such a degree that it will notsubstantially flow or experience a substantial change in shape. The expression"solidified, handleable binder" does not mean that the binder precursor is alwaysfully polymerized or cured, but that it is sufficiently polymerized or cured to allowremoval thereof from the production tool while the production tool continues tomove, without leading to substantial change in shape of the binder. After the binderis removed from the production tool, the binder can be exposed to an additionalenergy source to provide additional cure or polymerization of the binder. As used-7-W0 98/ 10896l015202530CA 02264872 1999-02-23PCT/US96/14570herein, the term "binder" is synonymous with the expression "solidified, handleablebinder".In one aspect, this invention involves a method of making a particulatematerial. In another aspect, this invention involves precisely shaped particlescomprising a solidified, handleable binder. The term precisely shaped means thatthe binder precursor is cured, polymerized or solidified in a cavity of a productiontool. After the binder precursor is solidified in the cavity, the resulting solidifiedbinder is removed from the cavity. In some instances during this removal process, aparticle is formed and during the removal process, edges of the particle may break.Additionally, when the particles are removed from the cavities, two, three or moreparticles may be interconnected at a common edge or otherwise remain together. Inother instances, a sheet of particles is removed and then this sheet is fiirtherprocessed (eØ, crushing, breaking, ball milling and the like) to form individualparticles. During this process of forming individual particles from a sheet ofparticles, the resulting individual particles may have rounded edges and/or several(i.e., two, three, four or more particles may remain together). It is within the scopeof this invention, that the term precisely shaped covers both broken edge particlesand rounded edge particles. Additionally it is within the scope of this invention,that the term precisely shaped_covers two, three, four or more individual particlesthat interconnect or otherwise remain together.In still another aspect, this invention involves abrasive articles, such asbonded abrasive articles, coated abrasive articles, and nonwoven abrasive articlesthat comprise the precisely shaped particulate material of this invention.FIG. 1 illustrates an apparatus capable of carrying out the method of thisinvention to make the particles of this invention. In apparatus 10, binder precursor12 is fed by gravity from a hopper 14 onto a production tool 16, which is in theform of an endless belt. The belt 16 travels over two rolls 18, 20, at least one ofwhich is power driven. FIG. 6 is a perspective view of a segment of the productiontool 16. As can be seen in FIG. 6, the production tool 16 is a three-dimensionalbody having a continuous surface 21 containing an opening 22 that provides accessto a cavity 23 in the three-dimensional body. The binder precursor 12 fills at least a-3-WO 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570portion of cavity 23. The binder precursor 12 then travels through a curing zone 24where it is exposed to an energy source 25 to at least partially cure the binderprecursor 12 to form a solidified, handleable binder. Particles of precisely shapedbinder material 26 are removed from the production tool 16 and collected in acontainer 28. External means 29, e.g., ultrasonic energy, can be used to helprelease the particles of binder material 26 from the production tool 16. Debris leftin the production tool can be cleaned away before any fresh binder precursor is fedto the production tool.FIG. 2 illustrates another variation of apparatus capable of carrying out themethod of this invention. Apparatus 30 comprises a carrier web 32 which is fedfrom an unwind station 34. Unwind station 34 is in the form ofa roll. The carrierweb 32 can be made ofa material such as paper, cloth, polymeric film, nonwovenweb, vulcanized fibre, combinations thereof and treated versions thereof. Thepreferred material for the carrier web 32 is a polymeric film, such as, for example, apolyester film. In FIG. 2, the carrier web 32 is transparent to radiation. A binderprecursor 36 is fed by gravity from a hopper 38 onto a major surface of the carrierweb 32. The major surface ofthe carrier web 32 containing the binder precursor 36is forced against the surface of a production tool 40 by means of a nip roll 42. Thesurface ofthe production tool 40 that contacts the carrier web is curved, but it isotherwise identical to that of the segment of the production tool shown in FIG. 6.The nip roll 42 also aids in forcing the binder precursor 36 into the cavities of theproduction tool 40. The binder precursor 36 then travels through a curing zone 43where it is exposed to an energy source 44 to at least partially cure the binderprecursor 36 to form a solidified, handleable binder. Next, the carrier web 32containing the solidified, handleable binder is passed over a nip roll 46. There mustbe sufficient adhesion between the carrier web 32 and the solidified, handleablebinder in order to allow for subsequent removal of the binder from the cavities ofthe production tool 40. The particles of binder material 48 are removed from thecarrier web 32 and collected in a container 50. External means 51, e.g., ultrasonicenergy, can be used to help release the particles 48 from the carrier web 32. TheW0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/ 14570carrier web 32 is then recovered at rewind station 52 so that it can be reused.Rewind station 52 is in the form ofa roll.Removal of the particles of binder material from the carrier web can becarried out efficiently by an alternative method. In this alternative, the carrier webcan contain a thin, water-soluble layer on the major surface thereof that receives thebinder precursor 36 from the hopper 38. The water-soluble layer will come intocontact with the binder precursor 36. After the binder precursor 36 is at leastpartially cured, the combination of carrier web 32 and solidified, handleable binderis subjected to a source of water, whereby the water dissolves the water-solublelayer on the carrier web 32, thereby bringing about separation of the particles ofbinder material from the carrier web 32. An example of a water-soluble layer usefulfor this variation is a layer of a water-soluble polymer, e.g., polyvinyl alcohol,polyvinyl pyrrolidone, and cellulose derivatives.FIG, 3 illustrates another variation of an apparatus capable of carrying outthe method of this invention. In apparatus 70, binder precursor 72 is knife coatedfrom a hopper 74 onto a production tool 76. The production tool is in the form ofacylindrical drum and has an axis 78. The continuous surface of the production tool76 is curved, but it is otherwise identical to the segment of the production toolshown in FIG. 6. As the production tool 76 rotates about the axis 78, the binderprecursor 72 travels through a curing zone 79 where it is exposed to an energysource 80 to at least partially cure the binder precursor 72 to form a solidified,handleable binder. Next, the particles of solidified, handleable binder 82 resultingfrom the curing step of the process are removed from the production tool 76 andcollected in a hopper 84. Removal is preferably carried out by mechanical means,e.g., a water jet. It is preferred that any debris remaining in the production tool 76be removed before any fresh binder precursor is introduced. Debris removal can beaccomplished by a brush, an air jet, or any other conventional technique. Althoughnot shown in FIG. 3, additional means can be used to aid in removing the particlesof binder from the production tool 76.FIG. 7 illustrates another variation of an apparatus capable of carrying outthe method of this invention. Apparatus 120 comprised a production tool 122 in_]0-WO 981108961015202530CA 02264872 1999-02-23PCT/US96/14570the form of web, which was fed from a first unwind station 124. Unwind station124 was in the form of a roll. The production tool 122 is preferably made of apolymeric material that was transparent to radiation, more preferably transparent toultraviolet and/or visible light. For example, the production tool can be made of apolymer having a polyethylene backbone and fluoroaliphatic groups attachedthereto. This polymer is further described in W0 92/ 15626, publishedSeptember 17, I990. The ethylene polymer is bonded to polyester. The productiontool can comprise a pattern of cavities in the form of pyramids having square basesand disposed such that the bases were butted up against each other. The surface ofthe production tool containing the cavities can be similar to the segment of theproduction tool shown in FIG. 6. The production tool 122 leaves the unwindstation 124, a carrier web 126 leaves a second unwind station 128. The carrier web126 can be made of a polyvinyl alcohol coated paper, commercially available fromSchoeller Technical Papers, Inc. of Pulaski, New York; stock number 89-84-4. Abinder precursor 130 is applied by means of a coater 132 into the cavities of theproduction tool 122. The portion of the production tool 134 containing the binderprecursor is brought into contact with the carrier web 126 by means of a nip roll136. The portion of the production tool 134 containing the binder precursor and‘the carrier web 126 is forced against a mandrel 138. The mandrel 138 rotates aboutan axis 140. Next, radiation energy from radiation source 141 in a curing zone 142is transmitted through the production tool 122 and into the binder precursor. Thesource of radiation energy can be a medium pressure mercury vapor ultraviolet lampoperating at 600 watts/inch (240 watts/cm). Upon exposure to the energy source,the binder precursor is converted into a solidified, handleable binder. Both theproduction tool containing the solidified, handleable binder and the carrier web arecontinuously moved through the curing zone 142 by means of the mandrel 138.The carrier web 126 is separated from the production tool containing the binder inthe vicinity ofa nip roll 143. The carrier web 126 is rewound on a rewind station144. Relative to FIG. 7, it is also within the scope of this invention to use anultrasonic horn on the backside of the carrier web to facilitate the removal of theparticles from the carrier web, In general, it is preferred that the ultrasonic horn be-1]-W0 98/108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570placed tightly against the back side of the carrier web, while the carrier web is undertension. An example of a commercially available ultrasonic horn commerciallyavailable from Branson under the model number “ lO8”.FIG. 8 illustrates another variation of an apparatus capable of carrying outthe method of this invention. Apparatus 160 comprised a production tool 162 inthe form of an endless belt, which traversed a series of rollers 164, at least one ofwhich is power-driven. A binder precursor 166 is applied by means of a knifecoater 168 into the cavities of the production tool 162. The binder precursor 166then travels through a curing zone 170 where it is exposed to a source of radiationenergy 172. The source of radiation energy can be a medium pressure mercuryvapor ultraviolet lamp operating at 600 watts/inch (240 watts/cm). The process iscontinuous and upon exposure to the ‘energy source l72, the binder precursor 166is converted into a solidified, handleable binder. The particles of binder 178preferentially should adheres to a smooth-surfaced roll 174. Immediately afterleaving the curing zone 170, the particles 178 are removed from thesmooth-surfaced roll 174 by a skiving means 176 and collected by means of vacuum(not shown).The production tool is a three-dimensional body having at least onecontinuous surface. The continuous surface contains at least one opening,preferably a plurality of openings, formed in the continuous surface. Each openingprovides access to a cavity formed in the three-dimensional body. As used in thiscontext, the term "continuous" means characterized by uninterrupted extension inspace; the openings and cavities are features in the continuous surface, but they donot break the surface into a plurality of individual surfaces. The production tool canbe in the form of a web, a belt, e.g., an endless belt, a sheet, a coating roll, or asleeve mounted on a coating roll. It is preferred that the production tool be onethat allows continuous operations, such as, for example, an endless belt or acylindrical coating roll that rotates about an axis. Typically, a cylindrical coatingroll is in the form of a right cylinder, has a diameter of from about 25 to about45cm, and is constructed of a rigid material. Apparatus utilizing a two-ended webcan also be adapted to provide continuous operations. The preferred materials for a-12-W0 98/ 10896l015202530CA 02264872 1999-02-23PCT/US96l 14570production tool are polymers, such as polyolefms, e.g., polypropylene, or metals,such as nickel. The production tool can also be formed from a ceramic material.A production tool made of metal can be fabricated by engraving,photolithography, hobbing, etching, knurling, assembling a plurality of metal partsmachined in the desired configuration, die punching, or other mechanical means, orby electroforming. The preferred method for preparing a metal production tool ormaster tool is diamond turning. Another preferred technique for making the mastertool and/or a metal production tool is to use a cutting knurl process. This cuttingknurl process is further described in PCT Patent Application No. PCT/US95/13074.For example, a cylindrical, eight inch diameter, 28 inch long, 1026 mild steelworkpiece was first plated with a thin layer of bright nickel to prevent corrosion andimprove adhesion to plated copper. Next, 0.050 in. of hard copper, 240 knoop,was plated over the bright nickel. One end ofthe plated workpiece was mounted ina four jaw chuck and the other end supported with a center in the tail stock ofaClausing engine lathe equipped with a low pressure pump and water-based coolant.The workpiece outer surface was faced off smooth, leaving 0.030 in. of hardcopper.A Zeus Cut-Knurling Tool Model No. 209 was provided with a high speedsteel ("HSS") first knurling wheel in the top position. First knurling wheel had a30° left tooth incline relative to the axis of the wheel, 36 teeth per inch ("TPI"),with the teeth having a 90° included angle at the tooth ridge. The tool was alsoprovided with a HSS second knurling wheel in the bottom position. The secondknurling wheel had a 0° tooth incline angle relative to the wheel axis, 36 TPI, with a90° included angle at the tooth ridge. Both wheel orientations were adjusted bysetting the wheel mounting posts to the 200 mm (7.9 inch) workpiece O. D.position. The wheel axes were each approximately 30° relative to the horizontalcenter plane of the Zeus Cut-Knurling Tool. The Cut-Knurling Tool was thenmounted on the cross slide of the clausing lathe. The height of the tool wasadjusted so that both wheels would contact the workpiece at the same time. Thefirst wheel in the top position was then removed. Coolant flow was directed at thesecond wheel to wash away chips as they formed.-13-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/ 145701) Second wheel was engaged with the workpiece. The lathe rotatedthe workpiece in a first direction (surface engaged with second wheel travelingupward) at 80 rpm with a tool feed rate parallel to the axis of the workpiece of0.010 inch/revolution from right to left. The depth of cut of the first wheel wasadjusted to give about 75% ofa full depth knurl.2) The second wheel was then removed and the first wheel wasreinstalled in the top position. The lathe rotated the workpiece in a record direction(surface engaged with first wheel traveling downward) at the same conditions asabove with tool direction from right to left parallel to the workpiece axis.3) The first wheel was removed, and the second wheel was reinstalledin the bottom position. This third step repeated the first step, except the tool wasadjusted to provide full knurl depth4) The second wheel was removed, and the first wheel was reinstalledin the top position. This fourth step repeated the second step, except the tool wasadjusted to provide full knurl depth.5) The first wheel was removed and the second wheel was reinstalled inthe bottom position. This fifth step repeated the third step again at full knurl depth.The resulting knurled workpiece surface was covered with a knurl pattern of‘"36.7 square-based pyramids per inch measured in the direction parallel to an edge ofthe base of the pyramid, having an average height of 0.0099 inches. The tops of thepyramids were rounded corresponding to the rounded valley of the knurl wheels.The peaks of the pyramidal pattern had a ll.5° helix angle with respect to a planeperpendicular to the longitudinal axis ofthe workpiece. The workpiece was coatedwith a protective layer of electroless nickel to prevent corrosion and improvepolymer release characteristics before use.The knurled workpiece described above was used to make a productiontooling. First the workpiece and a nip roll were installed below an extruder. Theknurled workpiece was held at 60°C (l40°F) and the nip roll at 21°C (70°F).Escorene “Polypropylene 3445” at 214°C (417°F) was extruded on to the knurledworkpiece and forced between the workpiece and nip roll as the workpiece and nipA 0.022 thick seamless film was collected atroll were rotated. inch-|4-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/145703.6 meters/minute (l 1.8 fpm). The surface of the film had an uninterrupted patternof pyramidal pockets on its surface which were the inverse of those on the knurledworkpiece. 'Extruding techniques are further described in the Encyclopedia of PolymerScience and Technology, Vol. 8, John Wiley & Sons, Inc. (1968), p. 651-665, andUS. Patent No. 3,689,346, col. 7, lines 30 to S5. The production tool may alsocontain a release coating to permit easier removal of the binder from the cavitiesand to minimize wear of the production tool. Examples of such release coatingsinclude hard coatings such as metal carbides, metal nitrides, metal borides, diamond,or diamond-like carbon. It is also within the scope ofthis invention to use a heatedproduction tool, which is preferably made from metal. A heated tool may alloweasier processing, more rapid curing, easier release ofthe shaped particles from thetool. Further information on production tools can be found in U.S. Patent No."5,435,816.In some instances, a polymeric production tool can be replicated from anoriginal master tool. This is especially preferred when the production tool is in theform ofa belt or web. One advantage of polymeric tools over metal tools is cost.Another advantage of polymeric tools is the capability of allowing radiation to passfrom the radiation source through the production tool and into the binder precursor.A polymeric production tool can be prepared by coating a molten thermoplasticresin, such as polypropylene, onto the master tool. The molten resin can then bequenched to give a thermoplastic replica of the master tool. This polymeric replicacan then be utilized as the production tool. Additionally, the surface of theproduction tool may contain a release coating, such as a silicone-based material or afluorochemical-based material, to improve the releasability of the binder from theproduction tool. It is also within the scope of this invention to incorporate a releaseagent into the polymer from which the production tool is formed. Typical releaseagents include silicone-based materials and fluorochemical-based materials. It iswithin the scope of this invention to prepare production tools from polymers thatexhibit good release characteristics. Such a polymer is described in W0 92/ 15626,published September 17, 1992. That reference describes a fluorochemical grafi-15-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570copolymer comprising: a base polymer comprising polymerized units derived frommonomers having terminal olefinic double bonds, having a moiety comprising afluoroaliphatic group grafted thereto. The grafted fluoroaliphatic group is generallyderived from a fluorochemical olefin comprising a fluoroaliphatic group and apolymerizable double bond.The fluoroaliphatic group ofthe fluorochemical olefin is generally bonded toSuch fluorochemicalthe polymerizable double bond through a linking group.olefins can be represented by the following formula:(Rr)aQ(CR=CH2)hwherein R represents hydrogen, trifluoromethyl, or straight-chain or branched-chainalkyl group containing l to 4 carbon atoms;a represents an integer from I to 10;b represents an integer from 1 to 6;Q represents an (a+b)-valent linking group that does not substantiallyinterfere with free radical polymerization; andRy represents a fluoroaliphatic group comprising a fully fluorinated terminalgroup containing at least seven fluorine atoms.The metal master tool can be made by the same methods that can be used tomake metal production tools. Other methods of preparing production tools aredescribed in U.S. Patent No. 5,435,816.If the production tool is made from a thermoplastic material, the conditionsof the method should be set such that any heat generated in the curing zone doesnot adversely affect the production tool.At least one continuous surface of the production tool contains at least onecavity, preferably a plurality of cavities. The solidified, handleable binder precursorwill acquire a shape corresponding to the shape of the cavity. A cavity can haveany geometric shape such as a pyramid, prism, cylinder, cone, or thin body havingopposed polygonal faces. The geometric shapes can be truncated versions of theforegoing. It is also within the scope of this invention that a given production tool-16-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570may contain a variety of cavities of different shapes or cavities of different sizes orboth. In the case of a web or belt, the cavity can extend completely through theproduction tool. The cavities can abutt or have land areas between them. It ispreferred that the sides of the cavities have a slope associated them to allow easierremoval ofthe binder from the production tool.It is also within the scope of this invention that the cavity may have othergeometric shapes such as a cube, block, sphere and the like.The cavities may all be the same shape with the same dimensions. In thisinstance, the plurality of precisely shaped particles will all have essentially the samesize and shape. Alternatively, the cavities may all be the same shape with differentdimensions. In this instance, there will be a particle size distribution of preciselyshaped particles. In yet another aspect, the cavities may all be the same dimensions,with different shapes. In this instance, the resulting precisely shaped particles willbe the same size, with different shapes. In still another embodiment, the cavitiesmay have different shapes and different sizes. In this instance, the resultingprecisely shaped particles will have different shapes and sizes.Binder precursors suitable for this invention comprise a thermosetting resinthat is capable of being cured by radiation energy or thermal energy. The binderprecursor can polymerize via a condensation curing mechanism or an additionmechanism. The preferred binder precursors polymerize via an addition mechanism.The binder precursor can polymerize via a free radical mechanism or a cationicmechanism or both mechanisms. The binder precursor can be unfilled or cancontain conventional filler material.The binder precursor is preferably capable of being cured by radiationenergy or thermal energy. Sources of radiation energy include electron beamenergy, ultraviolet light, visible light, and laser light. If ultraviolet or visible light isutilized, a photoinitiator is preferably included in the mixture. Upon being exposedto ultraviolet or visible light, the photoinitiator generates a free radical source or acationic source. This free radical source or cationic source then initiates thepolymerization of the binder precursor. A photoinitiator is optional when a sourceof electron beam energy is utilized.-17-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/14570Examples of binder precursors that are capable of being cured by radiationenergy include acrylated urethanes, acrylated epoxies, ethylenically unsaturatedcompounds, aminoplast derivatives having pendant unsaturated carbonyl groups,isocyanurate derivatives having at least one pendant acrylate group, isocyanatederivatives having at least one pendant acrylate group, vinyl ethers, epoxy resins,and combinations thereof. The term acrylate includes both acrylates andmethacrylates.Acrylated urethanes are diacrylate esters of hydroxy terminated isocyanateextended polyesters or polyethers. Examples of commercially available acrylatedurethanes include "UVlTHANE 782", available from Morton Thiokol Chemical,and "CMD 6600", "CMD 8400", and "CMD 8805", available from RadcureSpecialties.Acrylated epoxies are diacrylate esters of epoxy resins, such as thediacrylate esters of bisphenol A epoxy resin. Examples of commercially availableacrylated epoxies include "CMD 3500", "CMD 3600", and "CMD 3700", availablefrom Radcure Specialties.Ethylenically unsaturated compounds include both monomeric andpolymeric compounds that contain atoms of carbon, hydrogen and oxygen, andoptionally, nitrogen and the halogens. Oxygen or nitrogen atoms or both aregenerally present in ether, ester, urethane, amide, and urea groups. Ethylenicallyunsaturated compounds preferably have a molecular weight of less than about 4,000and are preferably esters resulting from the reaction of compounds containingaliphatic monohydroxy groups or aliphatic polyhydroxy groups and unsaturatedcarboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid,isocrotonic acid, maleic acid, and the like. Representative examples of acrylatesinclude methyl methacrylate, ethyl methacrylate, ethylene glycol diacrylate, ethylenediacrylate, triethylene glycol diacrylate,glycol methacrylate, hexanedioltrimethylolpropane triacrylate, glycerol triacrylate, pentaerthyitol triacrylate,pentaerythritol methacrylate, and pentaerythritol tetraacrylate. Other ethylenicallyunsaturated compounds include monoallyl, polyallyl, and polymethylallyl esters andamides of carboxylic acids, such as diallyl phthalate, diallyl adipate, and-18-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/ 14570N,N—diallyladipamide. Still other ethylenically unsaturated compounds includestyrene, divinyl benzene, and vinyl toluene. Other nitrogen-containing, ethylenicallyunsaturated compounds include tris(2—acryloyl-oxyethyl)isocyanurate, 1,3,5-tri(2-methyacryloxyethyl)-s-triazine, acrylamide, methylacrylamide, N-methylacrylamide,N,N-dimethylacrylamide, N-vinylpyrrolidone, and N-vinylpiperidone.The aminoplast resinsTheseThe aminoplast can be monomeric or oligomeric.have at least one pendant oL,B-unsaturated carbonyl group per molecule.ot,B-unsaturated carbonyl groups can be acrylate, methacrylate, or acrylamidegroups. Examples of such resins include N-hydroxymethyl-acrylamide,N,N'-oxydimethylenebisacrylamide, ortho and para acrylamidomethylated phenol,acrylamidomethylated phenolic novolac, and combinations thereof. These materialsare fi1l’Ii‘I6l‘ described in US. Patent Nos. 4,903,440; 5,055,112 and 5,236,472.lsocyanurate derivatives having at least one pendant acrylate group andisocyanate derivatives having at least one pendant acrylate group are furtherdescribed in US. Patent No. 4,652,274. The preferred isocyanurate material is atriacrylate of tris(hydroxyethyl) isocyanurate.Examples of vinyl ethers suitable for this invention include vinyl etherfiunctionalized urethane oligomers, commercially available from Allied Signal underthe trade designations "VB 4010'‘, "VE 4015", "VE 2010", "VE 2020", and"VE 4020". VEpoxies have an oxirane ring and are polymerized by the ring opening.Epoxy resins include monomeric epoxy resins and polymeric epoxy resins. Theseresins can vary greatly in the nature of their backbones and substituent groups. Forexample, the backbone may be of any type normally associated with epoxy resinsand substituent groups thereon can be any group free of an active hydrogen atomthat is reactive with an oxirane ring at room temperature. Representative examplesof substituent groups for epoxy resins include halogens, ester groups, ether groups,sulfonate groups, siloxane groups, nitro groups, and phosphate groups. Examplesof epoxy resins preferred for this invention include 2,2-bis[4-(2,3~epoxypropoxy)phenyl]propane (diglycidyl ether of bisphenol A) and materials underthe trade designation "Epon 828", "Epon 1004" and ”Epon 1001F", commercially-19-WO 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570available from Shell Chemical Co., "DER—331", "DER-332" and "DER-334",commercially available from Dow Chemical Co. Other suitable epoxy resins includeglycidyl ethers of phenol formaldehyde novolac (e.g., "DEN-431" and "DEN-428",commercially available from Dow Chemical Co.). The epoxy resins of the inventioncan polymerize via a cationic mechanism with the addition of an appropriatephotoinitiator(s). These resins are further described in U.S. Patent Nos. 4,318,766and 4,751,138.Examples of photoinitiators that generate a free radical source whenexposed to ultraviolet light include, but are not limited to, those selected from thegroup consisting of organic peroxides, azo compounds, quinones, benzophenones,nitroso compounds, acyl halides, hydrozones, mercapto compounds, pyryliumcompounds, triacrylimidazoles, bisimidazoles, chloroalkytriazines, benzoin ethers,benzil ketals, thioxanthones, and acetophenone derivatives, and mixtures thereofExamples of photoinitiators that generate a free radical source when exposed tovisible radiation are described in U.S. Patent No. 4,735,632.Cationic photoinitiators generate an acid source to initiate thepolymerization of an epoxy resin or a urethane. Cationic photoinitiators can includea salt having an onium cation and a halogen—containing complex anion ofa metal ormetalloid. Other cationic photoinitiators include a salt having an organometalliccomplex cation and a halogen-containing complex anion of a metal or metalloid.These photoinitiators are further described in U.S. Patent No. 4,751,138 (col. 6,line 65 through col. 9, line 45). Another example is an organometallic salt and anonium salt described in US. Patent No. 4,985,340 (col. 4, line 65 through col. 14,line 50); European Patent Applications 306,161; 306,162. Still other cationicphotoinitiators include an ionic salt of an organometallic complex in which the metalis selected from the elements of Periodic Groups IVB, VB, VIB, VIIB, and VIIIB.This photoinitiator is described in European Patent Application 109,581.The binder precursor may also be a condensation curable binder such as aphenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin and the like.There are two types of phenolic resins, resole and novolac. Resole phenolic resinshave a molar ratio of formaldehyde to phenol, of greater than or equal to one to-20-WO 98/10896l015202530CA 02264872 1999-02-23PCT/U S96! 14570one, typically between 15:10 to 30:10. Novolac resins have a molar ratio offormaldehyde to phenol, of less than to one to one. Examples of commerciallyavailable phenolic resins include those known by the tradenames "Durez" and"Varcum" from Occidental Chemicals Corp.; "Resinox" from Monsanto; "Arofene"from Ashland Chemical Co. and "Arotap" from Ashland Chemical Co. Additionaldetails on urea—formaldehyde resins can be found in U.S. Patent No. 5,486,219.It is also within the scope of this invention to use a binder precursor thatcontains a blend of a condensation curable resin a free radical curable resin. Forexample, a resole phenolic resin and an acrylate resin can be blended together toform the binder precursor. One preferred binder precursor comprises an acrylatemonomer such as trimethylol propane triacrylate, an aciylated isocyanurate resinsuch as triacrylate of tris(hydroxyethyl) isocyanurate, trimethylol propane triacrylateor pentaerythritol triacrylate land a resole phenolic resin. To help initiate thepolymerization ofthe acrylate based resins, the binder precursor is exposed to heatand/or a radiation energy source. To help initiate the polymerization of the resolephenolic resin, the binder precursor is typically exposed to heat. For example, thebinder precursor may comprise between about 10 to 90 parts by weight phenolicresin, preferably between 20 to 60 parts by weight phenolic resin and between about10 to 90 parts by weight free radical curable resin, preferably between 20 to 60parts by weight free radical curable resin.In one particularly useful embodiment, the binder precursor ‘may containabrasive grits. The cured binder precursor, i.e., the binder, functions to bond theabrasive grits together to form a precisely shaped abrasive particle. The abrasivegrits typically have an average particle size ranging from about 0.1 to 1500micrometers, preferably from about I to about 1300 micrometers, more preferablyfrom about 1 to about 500 micrometers, and most preferably from about 1 to about150 micrometers. It is preferred that the abrasive grits have a Mohs' hardness of atleast about 8, more preferably above 9. Examples of materials of such abrasive gritsinclude fiised aluminum oxide, ceramic aluminum oxide, white fused aluminumoxide, heat treated aluminum oxide, silica, silicon carbide, green silicon carbide,alumina zirconia, diamond, ceria, titanium diboride, boron carbide, cubic boron-2]-W0 98/108961015202530CA 02264872 1999-02-23PCTIU S96] 14570nitride, garnet, tripoli, and combinations thereof. The ceramic aluminum oxide ispreferably made according to a sol gel process, such as described in U.S. PatentNos. 4,314,827; 4,744,802; 4,623,364; 4,770,671; 4,881,951; 5,011,508; and5,213,591. The ceramic abrasive grit comprises alpha alumina and, optionally, ametal oxide modifier, such as magnesia, zirconia, zinc oxide, nickel oxide, hafnia,yttria, silica, iron oxide, titania, lanthanum oxide, ceria, neodymium oxide, andcombinations thereof. The ceramic aluminum oxide may also optionally comprise anucleating agent, such as alpha alumina, iron oxide, iron oxide precursor, titania,chromia, or combinations thereof. The ceramic aluminum oxide may also have ashape, such as that described in U.S. Patent Nos. 5,201,916 and 5,090,968. Theceramic abrasive grits may also contain a surface coating.The abrasive grit may also have a surface coating. A surface coating ‘canimprove the adhesion between the abrasive grit and the binder in the abrasiveparticle and/or can alter the abrading characteristics of the abrasive grit. Suchsurface coatings are described in US. Patent Nos. 5,011,508; 1,910,444;3,041,156; 5,009,675; 4,997,461; 5,213,591; and 5,042,991. An abrasive grit mayalso contain a coupling agent on its surface, such as a silane coupling agent.The binder precursor can contain a single type of abrasive grit, two or moretypes of different abrasive grits‘, or at least one type of abrasive grit with at least onetype of diluent material. Examples of materials for diluents include calciumcarbonate, glass bubbles, glass beads, greystone, marble, gypsum, polyvinylchloride, clay, SiO2, KBF4, Na2SiF(,, cryolite, organic bubbles, organic beads, andthe like.The binder precursor for use in this invention can further comprise optionaladditives, such as, for example, fillers (including grinding aids), fibers, lubricants,wetting agents, surfactants, pigments, dyes, coupling agents, plasticizers, antistaticagents, and suspending agents. Examples of fillers suitable for this inventioninclude wood pulp, vermiculite, and combinations thereof, metal carbonates, such ascalcium carbonate, e.g., chalk, calcite, marl, travertine, marble, and limestone,calcium magnesium carbonate, sodium carbonate, magnesium carbonate; silica, suchas amorphous silica, quartz, glass beads, glass bubbles, and glass fibers; silicates,-22-W0 98/10896IO15202530CA 02264872 1999-02-23PCT/U S96/ 14570such as talc, clays (montmorillonite), feldspar, mica, calcium silicate, calciummetasilicate, sodium aluminosilicate, sodium silicate; metal sulfates, such as calciumsulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate;gypsum; vermiculite; wood flour; aluminum trihydrate; metal oxides, such ascalcium oxide (lime), aluminum oxide, titanium dioxide, and metal sulfites, such ascalcium sulfite. For example, the precisely shaped particle may comprise by weightbetween about 20 to 100 parts binder, preferably 40 to lOO parts binder and 0 to 80parts filler, preferably 0 to 60 parts filler. In another embodiment, the preciselyshaped particle comprises by weight 20 to 90 parts binder, preferably 25 to 80 partsbinder, more preferably 30 to 70 parts binder; 10 to 80 parts abrasive grits,preferably 20 to 75 parts abrasive grit, more preferably 30 to 70 parts abrasive grit,1 to 60 parts filler, 5 to 50 parts filler and 10 to 40 parts filler.A grinding aid is defined as particulate material the addition of which to anabrasive article has a significant effect on the chemical and physical processes ofabrading, thereby resulting in improved performance. In particular, it is believedthat the grinding aid will (1) decrease the friction between the abrasive grits and theworkpiece being abraded, (2) prevent the abrasive grits from "capping", i.e., preventmetal particles from becoming welded to the tops of the abrasive grits, (3) decreasethe interface temperature between the abrasive grits and the workpiece and/or(4) decrease the grinding forces. In general, the addition of a grinding aid increasesthe useful life of the coated abrasive article. Grinding aids encompass a widevariety of different materials and can be inorganic or organic. Examples of grindingaids include waxes, organic halide compounds, halide salts, and metals and theiralloys. The organic halide compounds will typically break down during abradingand release a halogen acid or a gaseous halide compound. Examples of suchmaterials include chlorinated waxes, such as tetrachloronaphthalene,pentachloronaplithalene, and polyvinyl chloride. Examples of halide salts includesodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassiumtetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride,and magnesium chloride. Examples of metals include tin, lead, bismuth, cobalt,antimony, cadmium, iron, and titanium. Other grinding aids include sulfiir, organic-23-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/14570sulfur compounds, graphite, and metallic sulfides. It is also within the scope ofthisinvention to use a combination of different grinding aids and, in some instances, thismay produce a synergistic effect. The above-mentioned examples of grinding aidsis meant to be a representative showing of grinding aids, and it is not meant toencompass all grinding aids. Additional examples of grinding aids include sodiummetaphosphate, tripotassium phosphate and blends of polyvinyl chloride andpotassium tetrafluoroborate. The precisely shaped grinding aid particle maycomprise by weight between about 5 to 95 parts binder, preferably 25 to 70 partsbinder and 5 to 95 parts grinding aid, preferably 30 to 75 parts grinding aid.It is also within the scope of this invention to employ an acrylated binderthat contains a chlorine group. Examples of such binders include “Ebecryl 436”,“584”, “585”, “586” and “.588”, all commercially available from RadcureSpecialties, Inc. (Louisville, KY). Although not wishing to be bound by any theory,these chlorinated acrylate monomers may function both as a binder and a grindingaid. Under the appropriate abrading conditions the chlorine may be released duringabrading.of coupling suitable for this invention includeExamples agentsorgano-silanes, zircoaluminates, and titanates. A suitable coupling agent may beselected for the abrasive grit and/or the filler. The coupling agent may be applieddirectly into the mixture of binder plus abrasive grit and/or filler. Alternatively, theabrasive grit and/or filler may be pretreated with the coupling agent. Examples ofantistatic agents include graphite, carbon black, conductive polymers, humectants,vanadium oxide, and the like. The amounts of these materials can be adjusted toprovide the properties desired. The binder precursor can optionally include wateror an organic solvent.The precisely shaped particles may further comprise a plasticizer. Examplesof plasticizers include polyvinyl chloride, dibutyl phthalate, alkyl benzyl phthalate,polyvinyl acetate, polyvinyl alcohol, cellulose esters, phthalate esters, silicone oils,adipate and sebacate esters, polyols, polyols derivatives, t-butylphenyl diphenylphosphate, tricresyl phosphate, castor oil, combinations thereof and the like. Theamount of plasticizer can range from about 0 to about 70%, preferably from about-24-W0 98/ 108961015202530CA 02264872 1999-02-23PCTlUS96/145700% to about 65% by weight based on the total weight of the binder, not includingthe optional additives and abrasive particles.Examples of lubricants include waxes, metal salts of fatty acids, sulfiir basedcompounds, graphite, molybdenum disulfide, talc, boron nitride, silicones, siliconeoils, polyglycols, phosphate esters, silicate esters, neopentyl polyol esters andpolyphenyl ethers, fluorochemicals, mineral oils, combinations thereof and the like.The amount of these additives in the precisely shaped particle will depend inpart upon the desired properties. Examples of preferred additives include fillers,grinding aids, coupling agents and wetting agents. For example, for a diluentparticle, the precisely shaped particle may comprise binder and filler particles.Likewise for example, a diluent particle for an abrasive article may comprise binderand grinding aid. Alternatively an abrasive precisely shaped particle may comprisebinder, abrasive grits, optionally filler, optionally grinding aid and optionallycoupling agent.The precisely shaped particle may further contain a loading resistantadditive. "Loading" is a term used to describe the filling of spaces between abrasivegrits with swarf (the material abraded from the workpiece) and the subsequentbuild-up of that material. For example, during wood sanding, swarf comprised ofwood particles becomes lodged in the spaces between abrasive grits, dramaticallyreducing the cutting ability of the abrasive grits. Examples of such loading resistantmaterials include metal salts of fatty acids, urea-formaldehyde, waxes, mineral oils,crosslinked silanes, crosslinked silicones, phosphate esters, fluorochemicals and— combinations thereof. In one aspect of this invention, one or more of these loadingresistant materials can be incorporated into the precisely shaped particle. Theseresulting precisely shaped particles may be incorporated into an abrasive article,along with either abrasive agglomerates or abrasive grits. For example, a coatedabrasive may comprise a backing having a front and back side. A make coat ispresent on the front surface of the backing and this make coat serves to bond anabrasive layer to the front surface of the backing. The abrasive layer comprisesabrasive grits and precisely shaped particles containing a loading resistant material.Over the abrasive layer is a size coat.-25-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/ 14570The binder precursor may optionally further comprise an expanding agent.The expanding agent will typically increase the porosity of the precisely shapedparticle. The expanding agent can be any chemical or material that the presence ofwhich increases the volume of the precisely shaped particle. The expanding agentcan be steam or an organic solvent capable of swelling the particle.The binder precursor may further comprise a surfactant. Examples ofsurfactants include metal alkoxides, fluorochemicals, polyalkylene oxides, salts oflong chain fatty acids and the like. The surfactants may be cationic, anionic ornon-ionic. Examples of preferred surfactants include an anionic dispersing agentcommercially available from Byk Chemie, Wallingford, CT under the tradedesignation “Disperbyk Ill” and a polyethylene oxide based dispersantcommercially available from ICI Chemicals, of Wilmington, DE under the tradedesignation “Hypermer KD2”.If the particle contains abrasive grits, it is preferred that the particle becapable of breaking down during abrading. The selection and amount of the binderprecursor, abrasive grits, and optional additives will influence the breakdowncharacteristics ofthe particle. Additionally, the amount of porosity in the preciselyshaped particle will influence the break down and wear characteristics of theT‘ precisely shaped particle. The level or degree of porosity can be determined by thebinder chemistry, the additives (including abrasive grits), processing conditions andcombinations thereof. Thus, the amount of porosity should be tailored to thedesired break down or wear characteristics for a given use of the precisely shapedparticle. 'In order to form a mixture comprising a binder precursor and othermaterials, such as abrasive grits, the components can be mixed together by anyconventional technique, such as, for example high shear mixing, air stirring, ortumbling. A vacuum can be used on the mixture during mixing to minimizeentrapment of air. Alternatively in some instances it is preferred to entrap air orother gaseous materials into the abrasive slurry during mixing. This entrapped airtends to lead to a more porous precisely shaped particles.W0 98/1089615202530CA 02264872 1999-02-23PCT/US96/14570The binder precursor can be introduced to the cavity of the production toolby a dispensing means that utilizes any conventional technique, such as, forexample, gravity feeding, pumping, die coating, or vacuum drop die coating. Thebinder precursor can also be introduced to the cavities of the production tool bytransfer via a first carrier web. Examples of carrier webs include cloth backings(including untreated cloth backings, greige cloth backings, treated cloth backingsand the like), nonwoven substrates (including paper), polymeric film (includingprimed film, unprimed film, fibrous reinforced film and the like), vulcanized fiber,and any other suitable substrate type backing. The binder precursor can besubjected to ultrasonic energy during the mixing step or immediately prior to thecoating step in order to lower the viscosity ofthe binder precursor.Although the binder precursor is only required to fill a portion of the cavity,the binder precursor preferably completely fills the cavity in the surface of theproduction tool, so that the resulting particulate material will contain few voids orimperfections. These imperfections cause the shape of the particulate material todepart from the desired precise shape. Additionally, when the precisely shapedbinder material is removed from the production tool, an edge may break off, therebycreating an imperfection and detracting from the preciseness of the shape. It ispreferred that care be taken throughout the process to minimize such imperfections.Sometimes, voids or imperfections are desirable, because they create porosity in theresultant particles, thereby causing the particles to have greater erodibility. It is alsopreferred that the binder precursor not extend substantially beyond the plane of thecontinuous surface of the production tool and not extend substantially beyond theopenings ofthe cavities ofthe production tool.It is sometimes preferred that the binder precursor be heated prior to beingintroduced to the production tool, typically at a temperature in the range of fromabout 40 to 90°C. When the binder precursor is heated, its viscosity is reduced withthe result that it can flow more readily into the cavities of the production tool.The step following the introduction of the binder precursor into the cavitiesof the production tool involves at least partially curing the binder precursor byexposing it to radiation energy or thermal energy while it is present in the cavities of-27-WO 98/108961015202530CA 02264872 1999-02-23the production tool. Alternatively, the binder precursor can be at least partiallycured while it is present in the cavities ofthe production tool, and then post-curedafter the binder is removed from the cavities of the production tool. The post-curestep can be omitted. The degree of cure is sufficient that the resulting solidified,handleable binder will retain its shape upon removal from the production tool.Examples of sources of radiation energy for use in the curing zone includeelectron beam, ultraviolet light, visible light, and laser light. Electron beamradiation, which is also known as ionizing radiation, can be used at an energy levelof about 0.1 to about 20 Mrad, preferably at an energy level of about 1 to about10 Mrad.wavelength within the range of about 200 to about 400 nanometers, preferablyUltraviolet radiation refers to non-particulate radiation having awithin the range of about 250 to 400 nanometers. The dosage of radiation canrange from about 50 to about 1000 m]/cmz, preferably from about 100 mJ/cmz toabout 400 mJ/cmz. Examples of lamp sources that are suitable for providing thisamount of dosage provide about 100 to about 600 watts/inch, preferably fromabout 300 to about 600 watts/inch. Visible radiation refers to non-particulateradiation having a wavelength within the range of about 400 to about 800nanometers, preferably in the range of about 400 to about 550 nanometers. Theamount of radiation energy needed to sufficiently cure the binder precursor dependsupon factors such as the depth of the binder precursor while in the cavity, thechemical identity of the binder precursor, and the type of loading material, if any.Conditions for thermal cure range from a temperature of about 50 to about 200°Cand for a time of from fractions to thousands of minutes. The actual amount of heatrequired is greatly dependent on the chemistry of the binder precursor.After being at least partially cured, the resulting solidified, handleable binderwill preferably not strongly adhere to the surface of the production tool. In eithercase, at this point, the solidified binder precursor is removed from the productiontoo].There are several alternative methods for removing the solidified, handleableIn one method, the binder isbinder i.e., the binder, from the production tool.transferred directly from the production tool to a collector, e.g., a hopper. In this-23-PCT/US96I14570W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/14570method, if the production tool is made of a polymeric material, the binder can beremoved from the cavities by ultrasonic energy, a vacuum, an air knife, orcombinations thereof or other conventional mechanical means. If the productiontool is made of metal, the binder can be removed from the cavities by means of awater jet or air jet. If the production tool has cavities that extend completelythrough the production tool, e.g., ifthe production tool is a belt having perforationsextending completely therethrough, the binder can be removed by ultrasonic energy,mechanical force, water jet, air jet, or combinations thereof, or other mechanicalmeans, regardless of the material of construction of the production tool.In another method, the binder can be transferred indirectly from theproduction tool to a collector. In one embodiment, the binder can be transferredfrom the production tool to a smooth roll. The binder exhibits greater adhesion tothe smooth roll than to the production tool. The transferred binder can then be ’removed from the smooth roll by means of skiving, vacuum, water jet, air jet, orother mechanical means. In one particular embodiment, the binder can betransferred from the production tool to a major surface of a second carrier web.The binder exhibits greater adhesion to the major surface of the carrier web than tothe production tool. Examples of carrier webs include cloth backings (includinguntreated cloth backings, greige cloth backings, treated cloth backings and the like),nonwoven substrates (including paper), polymeric film (including primed film,unprimed film, fibrous reinforced film and the like), vulcanized fiber, and any othersuitable substrate type backing. Some preferred examples of carrier webs includecorona treated polyester film and cloth substrates containing a polyamide presizecoating. It is also within the scope of this invention to corona treat the carrier webprior to the precisely shaped particles being transferred to the carrier web.Additionally, the first and second carrier webs may be made from the same materialor a different material.The major surface of the carrier web to which the binder is transferred canbear a layer of material that is soluble in water or an organic solvent. The bindercan easily be removed from the carrier web by merely dissolving the material thatforms the soluble layer. in addition, mechanical means, e.g., skiving, vacuum, or-29-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/ 14570ultrasound, can be used to remove the binder. Ultrasonic energy can be applieddirectly over a major surface ofthe web or offto a side of a major surface of theweb. In another embodiment, the major surface of the carrier web can have aprimer thereon. Examples of primers suitable for the carrier web include ethyleneacrylic acid copolymer, polyvinylidene chloride, crosslinked hexanediol diacrylate,aziridine materials, and the like. The binder will preferentially adhere to the primedcarrier web. The binder can then be removed from the primed carrier web bymechanical means, e.g., skiving, vacuum, or ultrasound.After the binder is removed from the production tool, either by direct orindirect means, it is then converted into particles. In one mode of conversion, thebinder is released from the production tool in the form of particles. A given particlewill have a shape that is essentially the shape of the portion of the cavity of theproduction tool in which the particle was at least partially cured. An advantage ofthis mode is that the particles are already of the proper grade or of the properparticle size distribution for subsequent use, e.g., incorporation into an abrasivearticle. In the conventional manner of making abrasive particles, e. g., agglomerates,the abrasive particles have to be crushed and then screened to obtain proper particlesize distribution.In a second mode of conversion, the binder is released from the productioncomprising precisely shaped binder materialtool as a sheet of materialinterconnected by a thin layer of binder material, The binder is then broken orcrushed along the thin interconnecting portions to form the particles of thisinvention.The process of the invention lends itself to an economical means to makeabrasive particles comprising a plurality of abrasive grits distributed in a binder. Inthe preferred aspect of the invention, the process results in precisely shaped abrasiveparticles. However, it is within the scope of this invention to have an additionalsteps in which these precisely shaped abrasive particles are crushed or broken intorandomly shaped abrasive particles.In a variation, the production tool can be a drum or a belt that rotates aboutan axis. When the production tool rotates about an axis, the process can be-30-WO 98/108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570conducted continuously. When the production tool is stationary, as in processes ofthe prior art, the process is conducted batch-wise. The continuous process of thisinvention is usually more efficient and economical than the batch-wise processes of Vthe prior art.This invention also provides abrasive articles containing abrasive particlesmade according to the process of this invention. These abrasive articles can bebonded abrasive articles, coated abrasive articles, or nonwoven abrasive articles.For a bonded abrasive article, the precisely shaped abrasive particles are bondedtogether by a bonding medium to form a shaped mass, eg, a wheel, a cut-offwheel. Bonded abrasive articles are typically made by a molding process. For acoated abrasive article, the abrasive precisely shaped particles are bonded by abonding medium to a backing. For a nonwoven abrasive article, the abrasiveprecisely shaped particles are bonded by a bonding medium into a nonwoven fibroussubstrate.Backings suitable for preparing coated abrasive articles include polymericfilm, primed polymeric film, cloth, paper, vulcanized fibre, polymeric foam,nonwovens, treated versions thereof, and combinations thereof. Examples ofpolymeric film include polyester film, polyolefin films (polyethylene and propylenefilm), polyamide films, polyimide films and the like. Another example ofa backingis a fibrous reinforced thermoplastic such as that described in described in U.S.Patent No. 5,417,726. One popular coated abrasive backing is a cloth backing.The cloth is composed ofyarns in the warp direction, i.e., the machine direction andyarns in the fill direction, i.e., the cross direction. The cloth backing can be awoven backing, a stitchbonded backing, or a weft insertion backing. Examples ofwoven constructions include sateen weaves of 4 over one weave of the warp yarnsover the fill yarns; twill weave of 3 over one weave; plain weave of one over oneweave and a drill weave of two over two weave. In a stitchbonded fabric or weftinsertion backing, the warp and fill yarns are not interwoven, but are oriented in twodistinct directions from one another. The warp yarns are laid on top ofthe fill yarnsand secured to another by a stitch yarn or by an adhesive. The yarns in the clothbacking can be natural, synthetic or combinations thereof. Examples of natural-3]-W0 98/1089610152025CA 02264872 1999-02-23PCT/US96/14570yarns include cellulosic such as cotton, hemp, kapok, flax, sisal, jute, carbon, manilaand combinations thereof. Examples of synthetic yarns include polyester yarns,polypropylene yarns, glass yarns, polyvinyl alcohol yarns, polyimide yarns, aromaticpolyamide yarns, rayon yarns, nylon yarns, polyethylene yarns and combinationsthereof. The preferred yarns of this invention are polyester yarns, nylon yarns, amixture of polyester and cotton, rayon yarns and aromatic polyamide yarns. Thecloth backing can be dyed and stretch, desized or heat stretched. Additionally theyarns in the cloth backing can contain primers, dyes, pigments or wetting agents.The yarns can be twisted or texturized. The coated abrasive backing may have anoptional saturant coat, presize coat and/or backsize coat. These coats may seal thebacking and/or protect the yams or fibers in the backing. The addition of thepresize coat or backsize coat may additionally result in a "smoother" surface oneither the front or back side of the backing. The backsize coat may contain anantistatic material or a lubricant material.Referring to FIGS. 4 and 5, coated abrasive article 100 contains twocoatings for binding the abrasive particles to the backing. Coating 102, commonlyreferred to as a make coat, is applied over backing 104 and bonds abrasive particles106 to backing 104. Coating 108, commonly referred to as a size coat, is appliedover abrasive particles 106 and reinforces abrasive particles 106. There may also bea third coating 110, commonly referred to as a supersize coat, applied over the sizecoat 108. As mentioned previously, the abrasive particles 106 comprise a pluralityof abrasive grits 1 12 and a binder 1 14. The abrasive particles can be applied to thebacking by conventional techniques, eg, by drop coating or by electrostaticcoating. Depending upon the coating method, the abrasive particles can either beoriented in a non-random manner as in FIG. 4 or oriented in a random manner as inFIG. 5.The material for bonding the abrasive material to a substrate or togethercomprises a cured resinous adhesive and optional additives. Examples of resinousadhesives suitable for this invention include phenolic resins, aminoplast resins,urethane resins, epoxy resins, acrylate resins, aciylated isocyanurate resins,urea-formaldehyde resins, isocyanurate resins, acrylated urethane resins, vinylW0 98/108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570ethers, acrylated epoxy resins, and combinations thereof. The optional additivesinclude fillers (including grinding aids), fibers, lubricants, wetting agents,surfactants, pigments, dyes, coupling agents, plasticizers, and suspending agents.Examples of fillers include talc, calcium carbonate, calcium metasilicate, silica andcombinations thereof. The amounts of these materials are selected to provide theproperties desired.Examples of fillers that can be incorporated into either a coated abrasivearticle, a structured abrasive article, a nonwoven abrasive article or a bondedabrasive article include wood pulp, vermiculite, and combinations thereof, metalcarbonates, such as calcium carbonate, e.g., chalk, calcite, marl, travertine, marble,and limestone, calcium magnesium carbonate, sodium carbonate, magnesiumcarbonate; silica, such as amorphous silica, quartz, glass beads, glass bubbles, andglass fibers; silicates, such as talc, clays (montmorillonite), feldspar, mica, calciumsilicate, calcium metasilicate, sodium aluminosilicate, sodium silicate; metal sulfates,such as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate,aluminum sulfate; gypsum; vermiculite; wood flour; aluminum trihydrate; metaloxides, such as calcium oxide (lime), aluminum oxide, titanium dioxide, and metalsulfites, such as calcium sulfite. For example, the abrasive article bonding mediummay comprise by weight between about 0 to 80 parts filler, preferably 0 to 70 partsfiller and more preferably about 10 to 55 parts filler.Examples of grinding aid that can be incorporated into either a coatedabrasive article, a nonwoven abrasive article or a bonded abrasive article includewaxes, organic halide compounds, halide salts, and metals and their alloys. Theorganic halide compounds will typically break down during abrading and release ahalogen acid or a gaseous halide compound. Examples of such materials includechlorinated waxes, such as tetrachloronaphthalene, pentachloronaphthalene, andpolyvinyl chloride. Examples of halide salts include sodium chloride, potassiumcryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodiumtetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride.Examples of metals include tin, lead, bismuth, cobalt, antimony, cadmium, iron, andtitanium. Other grinding aids include sulfur, organic sulfur compounds, graphite,WO 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570and metallic sulfides. Still other examples of grinding aid include sodiummetaphosphate, tripotassium phosphate and blends of polyvinyl chloride andpotassium tetrafluoroborate. It is also within the scope of this invention to use acombination of different grinding aids and, in some instances, this may produce asynergistic effect. For example, the abrasive article bonding medium may compriseby weight between about 0 to 80 parts grinding aid, preferably 0 to 70 partsgrinding aid and more preferably about 10 to 55 parts grinding aid.Examples of coupling agents that can be incorporated into the bondingmedium for a coated abrasive, nonwoven abrasive or bonded abrasive includeorgano-silanes, zircoaluminates, and titanates. A suitable coupling agent may beselected for the abrasive grit and/or the filler. The coupling agent may be applieddirectly into the mixture of bonding medium plus abrasive grit and/or filler.Alternatively, the abrasive grit and/or filler may be pretreated with the couplingagent.It is also within the scope ofthis invention to incorporate a precisely shapedfiller particle and/or a precisely shaped grinding aid particle into the bondingmedium for the abrasive article. In general, the particle size of these preciselyshaped filler particles and/or precisely shaped grinding particles should be controlledso that the bonding medium can be appropriately processed when the abrasivearticle is manufactured. For example in a coated abrasive or nonwoven -abrasive,the particle size of the precisely shaped filler particles and/or precisely shapedgrinding aid particles should be less than about 100 micrometers, preferably lessthan about 50 micrometers such that the resulting make and/or size coat can beproperly coated.A nonwoven abrasive article comprises an open, porous, fibrous, nonwovensubstrate having a plurality of abrasive particles bonded into the substrate. Thistype of nonwoven abrasive article is described in U.S. Patent No. 2,958,593.Bonded abrasives products typically comprise a plurality of abrasive gritsbonded together by means of a bonding medium to form a shaped mass. Thepreferred bonding medium is typically a cured or crosslinked organic binder. Theshaped mass is preferably in the form a grinding wheel. However, there are-34-W0 98/10896l015202530CA 02264872 1999-02-23PCT/U S96/ 14570numerous forms of bonded abrasives such as honing stones, polishing sticks, sawblades, cutting sticks, mounted points, snagging wheels, dressing tools, cup wheels,honing stones, cut off wheels, depressed center wheels, flap wheels and the like.The grinding wheel can range in diameter from about 0.1 cm to 2 meters andtypically between l cm to 2 meters. The grinding wheel thickness can range fromabout 0.001 cm to about 1 meter, typically between 0.0! cm to 0.5 meter. Thebonded abrasive article may be dressed by any conventional technique during thelife of the bonded abrasive article. Alternatively, the bonded article can beformulated such that the resulting construction does not need to be dressed.The precisely shaped particles ofthe invention may be incorporate into a cutoff wheel. A cut off wheel typically has a diameter between I cm to 500 cm andhas thickness between 0.01 cm to 19 cm. The cut off wheel may also contain areinforcing fabric. Examples of reinforcing substrates include textiles, meshes andthe like. The yarns in the reinforcing substrates may be made from syntheticorganic fibers such as nylon, polyester, rayon, cotton or the like. Alternatively theyarns in the reinforcing substrates may be made of inorganic fibers such asfiberglass, alumina, metal or the like.The bonded abrasive may utilize an organic bonding medium, a vitrifiedbonding medium or a metal bonding medium. The organic bonding mediums aredescribed above, along with the additives that can be incorporated into the organicbonding medium. Other organic bonding mediums include rubber bonds and shellacbonds. Additionally, the bonded abrasive may contain a rubber based bondingmedium. One common bonding medium is a novolac phenolic bonding medium thatis crosslinked with hexamethylenetetramine. Examples of commercially availablephenolic bonding mediums include Varcum 8l2l (liquid resole) and Varcum 7909(powdered novolac) from Varcum Chemical Company, Niagara Falls, NY. If thebonded abrasive is made via a molding process, it is preferred to use a combinationof powdered organic bonding mediums and liquid organic bonding mediums.During molding, the liquid organic bonding medium is first mixed with the abrasivegrits and/or precisely shaped particles. This results in the liquid wetting the surfaceof the abrasive grits and/or precisely shaped particles. Next, the dry or powdered-35-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96l14570bonding mediums are mixed with the liquid bonding medium/abrasive grits. Insome instances, it may be preferred to include reinforcing fibers in the bondingmedium. The addition of these reinforcing fibers may improve the bonded wheelstrength, wear properties or heat resistance properties. Examples of suchreinforcing fibers include glass fibers, metal fibers, organic fibers (e.g., aramidfibers, polyolefin fibers, polyamide fibers, polyester fibers and the like), inorganicfibers (e.g., alumina fibers, silicate fibers and the like).The bonded abrasive article typically contains some form of porosity. Theamount of the porosity strongly influences this break down characteristic. Ingeneral, many bonded abrasives are designed for the desired abrading application.The bonded abrasive can have any range of porosity, for example the porosity insome instances ranges fi'om about I% to 50%, typically 1% to 40% by volume.There are several means to incorporate porosity into a bonded abrasive article. Onesuch means is the use of porous bodies, diluents or other sofi particles. Someexamples of porous bodies include hollow spheres of glass, alumina, metal orpolymers. In some instances, the addition of certain fillers will increase the porosityand/or break down characteristics of the bonded abrasive. Another means is toincorporate an expanding agent in the bonded abrasive and typical expanding agentsare described above. Still another such means is to use fugitive materials thatduring the heating of either the organic or vitreous bonding medium willdecompose, thereby leaving porosity. These fugitives materials are typically utilizedmore in vitrified wheels than in resin bonded wheels. Examples of such fugitivematerials include walnut shells, sugar, diphthalic hydrocarbon, thermoplasticparticles and the like.The bonded abrasive article of the invention may be made by compressionmolding, injection molding or transfer molding or the like. The molding can beeither by hot or cold pressing or any suitable manner well known to those skilled inthe art. After the bonded abrasive article is molded, it is typically heated to helpinitiate the polymerization or curing of the bonding medium. The bonded abrasivemay be made in such a manner that the abrasive grain of the invention is onlypresent in the outer portion or rim of the wheel.-36-WO 98/108961015202530CA 02264872 1999-02-23PCTlUS96/ 14570The depressed center wheels usually grind on the flat face. In the center ofthe wheels is a mounting means to connect this wheel to a tool. The mountingmeans may be a center hole forming an arbor hole. In many instances thesedepressed center wheels contain a flat center or a depressed center. The depressedcenter wheels may be molded to the shape of a shallow dish or saucer with curvedor straight flaring sides. The back side (i.e., the side opposite of the abrasivecoating) of the depressed center wheels may contain a reinforcing fabric, areinforcing paper backing or some other support means such as a metal or plasticplate.During use, the bonded abrasive can be used dry or wet. During wetgrinding, the bonded abrasive is used in conjunction with water, oil based lubricantsor water based lubricants.The abrasive articles of this invention may further contain conventionalabrasive agglomerates or individual abrasive grits or both Conventional abrasiveagglomerates are further described in U.S. Patent Nos. 4,311,489; 4,652,275; and4,799,939. Individual abrasive grits can also be selected to have a precise shape.Examples of individual abrasive grits include fused aluminum oxide, ceramicaluminum oxide, heat treated aluminum oxide, silicon carbide, alumina zirconia,‘ diamond, ceria, cubic boron nitride, garnet, and combinations thereof. At least10%, preferably at least 50%, and most preferably at least 70%, of the abrasivematerial should be the precisely shaped abrasive particles of this invention. In acoated abrasive article, the individual abrasive grits can be disposed over theprecisely shaped abrasive particles. Alternatively, the individual abrasive grits canbe disposed underneath the precisely shaped abrasive particles. The individualabrasive grit can be disposed between two precisely shaped abrasive particles.It is preferred that the precisely shaped particles have no dimension greaterthan 2500 micrometers. It is preferred that the size of the precisely shaped particlesrange from 0.1 to 1500 micrometers, more preferably from 0.1 to 500 micrometersand even more preferably 50 to 500 micrometers. As indicated previously, theprecise shape corresponds to portions of the surface of the production tool, e.g.,cavities formed in the surface of the production tool. The particles of this invention-37-WO 98/10896l015202530CA 02264872 1999-02-23PCT/US96/ 14570have a precise shape. This precise shape is attributable to the binder precursor'sbeing at least partially cured in the cavities of the production tool. There may,however, be minor imperfections in the particles that are introduced when theparticles are removed from the cavities. If the binder precursor is not sufficientlycured in the cavities, the binder precursor will flow, and the resulting shape will notcorrespond to the shape of the cavities. This lack of correspondence gives animprecise and irregular shape to the particle. This precise shape can be anygeometrical shape, such as a cone, triangular prism, cylinder, pyramid, sphere, and abody having two opposed polygonal faces separated by a constant or varyingdistance, i.e., a polygonal platelet. Pyramids preferably have bases having three orfour sides. The abrasive article may contain a variety of abrasive particles havingdifferent shapes. FIG. 7 is a scanning electron photomicrograph taken at about 300magnification of an abrasive particle in the form of a pyramid having a triangularbase.The weight percentages ofthe grinding aid particulate and the binder in theprecisely shaped grinding aid particle will depend on several factors, such as theintended use of the abrasive article and the particle size and distribution of theabrasive grit used in the abrasive article. Typically, the percent by weight grindingaid particulate will range from about 5 to 95 percent and the percent by weightbinder will range from about 95 to 5 percent. Preferably, the percentage, based onweight, of grinding aid particulate ranges from 20 to 75 percent and the percentageof binder ranges from 80 to 25 percent.In another aspect of this invention, the precisely shaped particles do notcontain any abrasive grits. These precisely shaped particles that are free of abrasivegrits can be used in a coated abrasive article as a diluent particle. For example, acoated abrasive article may comprise a backing, and bonded to the backing areabrasive grits and precisely shaped particles that are free of abrasive grits.Alternatively, the coated abrasive article may comprise a backing, a first coat ofcured resinous adhesive (make coat) applied over the front surface of the backing,abrasive grits and precisely shaped particles, wherein the grits and precisely shapedparticles are secured to the backing by means of the make coat. Over the abrasive-3 3-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570grits and precisely shaped particles is a second coat of cured resinous adhesive (sizecoat).The precisely shaped abrasive particles can be coated or placed randomlyonto the backing. Alternatively, the precisely shaped abrasive particles can beoriented on the backing in a specified direction. In the case of precisely shapedparticles having the shapes of pyramids, cones, and prisms (e.g., triangular-shapedprisms), the particles can be oriented so that their bases point toward the backingand their vertexes point away from the backing, as in FIG. 4, or they can beoriented so that their veitexes point toward the backing and their bases point awayfrom the backing, as do four ofthe particles in FIG. 5. With respect to pyramidsand cones, the vertex referred to is the common vertex.In general, the coated abrasive article will comprise a backing having a frontand back surface. Over the front surface of the backing, is a make coat and thismake coat serves to bond an abrasive layer to the backing. Optionally, over theabrasive layer is a size coat. Optionally, over the size coat is a supersize coat. Onepreferred make coat is a crosslinked resole phenolic resin containing filler particlessuch as calcium carbonate. One preferred size coat is a crosslinked resole phenolicresin containing filler particles such as calcium carbonate. Another preferred sizecoat is a crosslinked resole phenolic resin containing grinding aid particles such ascryolite, chiolite or tetrafluoroborate particles. One preferred supersize coat is acrosslinked epoxy resin, optionally a thermoplastic polymer and grinding aidparticles such as cryolite, chiolite or tetrafluoroborate particles. This type ofsupersize coat is further described in European Patent Application No. 486,308 andU.S. Patent No. 5,441,549. The coated abrasive may optionally contain a supersizecoating which prevents the coated abrasive from "loading". The various materialsforming either the make coat, size coat and/or supersize coat will depend in partupon the final coated abrasive product requirements and the intended abradingapplication for the coated abrasive.The precisely shaped particles of the invention may also be incorporated intoa lapping coated abrasive article. This lapping coated abrasive article comprises abacking having a front and back surface and an abrasive coating bonded to the front-3 9-W0 98l108961015202530CA 02264872 1999-02-23PCTIUS96/14570surface of the backing. The abrasive coating comprises a plurality of preciselyshaped abrasive particles distributed throughout a make coat.The precisely shaped particles may also be incorporated into a structuredabrasive article. In general, a structured abrasive article may comprise a plurality ofprecisely shaped abrasive composites bonded to a backing. These abrasivecomposites may include the precisely shaped particles, with or without abrasivegrits in these particles. Relative to a structured abrasive article, it is preferred thatthe particle size of the precisely shaped particle be less than about 50 micrometers,preferably less than about 25 micrometers.The coated abrasive may be converted into a variety of different shapes andforms such as belts, discs, sheets, tapes, daises and the like. The belts may contain asplice or a joint, alternatively the belts may be spliceless such as reported inInternational application W0 93/1291 1. Additionally, the coated abrasive may besecured to a support pad either through a pressure sensitive adhesive or a hook andloop attachment system.In general, the nonwoven abrasive article comprises an open, lofiy, porousnonwoven substrate. The nonwoven substrate comprises fibers and these fibersmay be polyamide fibers (e.g., nylon fibers), polyester fibers, Polyolefm fibers,combinations thereof and the like. The fibers in the nonwoven substrate may begenerally bonded together at their points of mutual contact with a prebond coatingor prebond bonding medium. An abrasive layer is bonded to this open, porousnonwoven substrate. The abrasive layer may consist of a mixture of abrasive gritsand make coat. This abrasive layer is formed by coating (e.g., roll coating or spraycoating) a mixture of the make coat precursor and abrasive grits or precisely shapedabrasive particles. Alternatively, the nonwoven abrasive article may comprise amake coat present in and over the nonwoven substrate, an abrasive layer bonded inand to the nonwoven substrate by means of the make coat. In this nonwovenabrasive article construction, the make coat and abrasive layer are applied indifferent steps. Additionally, an optional size coat may be present over the abrasivelayer for both types of nonwoven abrasive articles. The nonwoven abrasive article-40-WO 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570may be converted into a wide variety of forms including sheets, discs, rolls, handpads, endless belts, wheels and the likeIn general, a bonded abrasive article comprises a plurality of abrasive gritsbonded together by a bonding medium (e.g., cured resinous adhesive) to form ashaped mass. At least a portion of the outer surface of the bonded abrasive isdesigned to contact a workpiece. This outer surface that contacts the workpiececomprises the bonding medium and an abrasive layer. The abrasive layer willcomprise the precisely shaped particles of the invention and optionally otherparticles. These different abrasive layer configurations will be described below.There are many different coated abrasive articles, nonwoven abrasivearticles, structured abrasive articles and bonded abrasive articles that can befabricated using the precisely shaped particles ofthis invention. For example, theabrasive layer may comprise solely just the precisely shaped abrasive particles in‘which these particles consist essentially of abrasive grits and binder. Alternatively,the precisely shaped abrasive particles may comprise abrasive grits, grinding aids,optionally other additives and binder.In another example, the abrasive layer may comprise a mixture of individualabrasive grits and precisely shaped abrasive particles. The individual abrasive gritsand the abrasive grits in the precisely shaped abrasive particles may be the same orthey may be different. The individual abrasive grits may be randomly shaped orhave a shape associated with them, such as a rod or triangular shape. These shapedindividual abrasive grits are further described in U.S. Patent Nos. 5,009,676;5,035,723; 5,090,968; 5,103,598; 5,201,916 and 5,366,523. Likewise the particlesize of the individual abrasive grits and the abrasive grits in the precisely shapedabrasive particles may be the same or they may be different. Analogously, theparticle size of the individual abrasive grits and the particle size of the preciselyshaped abrasive particle may be the same or they may be different.In still another example, the abrasive layer may comprise a mixture ofindividual abrasive grits and precisely shaped grinding aid particles. These preciselyshaped grinding aid particles consist essentially of grinding aid and binder.Similarly, the abrasive layer may comprise a mixture of precisely shaped abrasive-4]-W0 98/1089610I5202530CA 02264872 1999-02-23PCT/US96/14570particles and precisely shaped grinding aid particles. The particle size of theindividual precisely shaped abrasive particles and the particle size of the preciselyshaped grinding aid particles may be the same or they may be different. The surfacearea percentage of the precisely shaped grinding aid particles in the abrasive layermay range from about 5 to 90, preferably 20 to 40. Additionally the method ofmaking the abrasive article may result in the individual abrasive grits either over,under and/or between the precisely shaped grinding aid particles.The precisely shaped grinding aid particles have the potential to be veryadvantageous in abrasive articles. In some instances the bonding medium may notbe compatible with a grinding aid For example, sometimes resole phenolic resinsare used as a precursor for the bonding medium and this resole phenolic resin iscured or crosslinked with basic pH. In some instances, acidic grinding aids may bedesired such as potassium tetrafluoroborate. In these situations, the potassiumtetrafluoroborate may interfere with the polymerization of certain resole phenolicresins. This level of interference will depend in part upon the chemistry of theparticular resole phenolic resin. A precisely shaped grinding aid particle will havethe grinding aid essentially encapsulated within the binder. Thus, the grinding aid inthis particle should have minimal interaction on the curing or polymerization of thebonding medium.It is also within the scope of this invention to have abrasive articlescomprising a plurality of abrasive grits and precisely shaped grinding aid particles inthe abrasive layer and include a grinding aid in the bonding medium. The grindingaid in the bonding medium may be the same or different from the grinding aid in theprecisely shaped grinding aid particle.In yet another example, the abrasive layer may comprise a mixture ofindividual abrasive grits and precisely shaped loading resistant particles. Theseprecisely shaped loading resistant particles comprise loading resistant materials andbinder. The particle size of the individual precisely shaped abrasive particles and theparticle size of the precisely shaped loading resistant particles may be the same orthey may be different. The volume ratio between the individual abrasive grits andthe precisely shaped loading resistant particles may range from about 0.1 to 10 parts-42-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/14570individual abrasive grits to 0.1 to 10 parts precisely shaped loading resistantparticles. Additionally the method of making the abrasive article may result in theindividual abrasive grits either over, under and/or between the precisely shapedloading resistant particles.Similarly, the abrasive layer may comprise a mixture of precisely shapedabrasive particles and precisely shaped filler particles. In a similar example, theabrasive layer may comprise a mixture of individual abrasive grits and preciselyshaped filler particles. These precisely shaped filler particles comprise fillermaterials and binder. The volume ratio between the individual abrasive grits or theprecisely shaped abrasive particles, and the precisely shaped filler particles mayrange from about 0.| to l0 parts individual abrasive grits or precisely shapedabrasive particles to 0.l to 10 parts precisely shaped filler particles. Additionallythe method of making the abrasive article may result in the individual abrasive gritsor precisely shaped abrasive particles either over, under and/or between theprecisely shaped tiller particles.Additionally, the abrasive layer may comprise precisely shaped abrasiveparticles and diluent particles. These diluent particles can be selected from thegroup consisting of: 1) an inorganic particle (non abrasive inorganic particle), 2) anorganic particle, 3) a composite diluent particle containing a mixture of inorganicparticles and a binder and 4) a composite diluent particle containing a mixture oforganic particles and a binder. The particle size ofthese diluent particles can rangefrom about 0.0] to 1500 micrometers, typically between l to 1000 micrometers.The diluent particles may have the same particle size and particle size distribution asthe precisely shaped abrasive particles. Alternatively, the diluent particles may havea different particle size and particle size distribution as the precisely shaped abrasiveparticles. The weight ratio of the precisely shaped abrasive particles to the diluentparticle can range anywhere from about 1 to 99 parts precisely shaped abrasiveparticle ofthe invention to l to 99 parts diluent particle, typically between 10 to 90parts precisely shaped abrasive particle of the invention to 10 to 90 parts diluentparticle, preferably between 25 to 75 parts precisely shaped abrasive particle to 25to 75 parts diluent particle, more preferably between 35 to 65 parts precisely shaped-43-W0 98/10896l015202530CA 02264872 1999-02-23PCT/U S96/ 14570abrasive particle to 35 to 65 parts diluent particle, and most preferably between 50to 50 parts precisely shaped abrasive particle to 50 to 50 parts diluent particle.This representation of different configurations of the precisely shapedparticles in the abrasive layer is not meant to be limiting, but rather exemplary ofdifferent uses of precisely shaped particles in an abrasive article.Another aspect of this invention pertains to a novel coated abrasive articleand a method of making a coated abrasive article. The coated abrasive article,comprises:(a) a backing having a front and back surface;(b) a make coat present on the front surface ofthe backing:(c) an abrasive layer bonded to the front surface of the backing bymeans ofthe make coat, wherein the abrasive layer comprises a plurality of abrasivegrits; and(d) a size coat present over the abrasive layer, wherein the size coatcomprises:(1) a solidified bonding medium and(2) a plurality of precisely shaped grinding aid particles , whereinthe precisely shaped grinding aid particles comprise a binder and a plurality ofgrinding aid particulates.The method of making a coated abrasive article, comprises the steps of:(a) providing a backing having a front and back surface;(b) applying a make coat precursor over the front surface of thebacking; '(C) applying a plurality of abrasive grits into the make coat precursor;(d) subjecting the backing, make coat precursor and abrasive grits toconditions to at least partially solidifying the make coat precursor and to form asolidified make coat;(e) applying a size coat precursor over the abrasive grits;(f) applying a plurality of precisely shaped grinding aid particles into thesize coat precursor, wherein the precisely shaped grinding aid particles comprise abinder and a plurality of grinding aid particulates and-44-WO 98/10896l015202530CA 02264872 1999-02-23PCT/U S96/ 14570(g) subjecting the backing, solidified make coat, abrasive grits and sizecoat precursor to conditions at least partially solidifying the size coat precursor toform a coated abrasive article.The coated abrasive article can be made according to the followingprocedure. A backing having a front surface and a back surface is provided. Thefront surface of the backing is coated with a first curable bonding mediumcomprising a resinous adhesive (commonly referred to as a make coat); then theprecisely shaped grinding aid particles and, optionally, the individual abrasive gritsare coated or applied into the first curable bonding medium. The precisely shapedgrinding aid particles and optional abrasive grits can be drop coated or electrostaticcoated. The first curable bonding medium is then solidified or partially cured toform a cured resinous adhesive. Optionally, a second curable bonding medium(commonly referred to as a size coat) comprising a resinous adhesive can be appliedover the precisely shaped particles and then solidified or cured to form a curedresinous adhesive. The second curable bonding medium can be applied prior to orsubsequent to solidification or curing ofthe first curable bonding medium.Alternately, individual abrasive grits can be first coated or applied into thefirst bonding medium and then the precisely shaped grinding aid particles coated ontop.It is within the scope of this invention to provide a coating on the outer-‘surface of any of the precisely shaped particles. The coating can be continuous ordiscontinuous. Examples of coatings suitable for the particles include metalcoatings, metal oxide coatings, carbide coatings, nitride coatings, boride coatings,carbon coatings, diamond coatings, diamond like carbon coatings, and the like.Alternatively an organic coating can be present on the surface of the particle. Theorganic coating may also contain fillers, coupling agents, antistatic agents, grindingaids, and the like.The selection and amount of the coating will depend upon the desiredproperties of the particle. For instance, some coatings will result in aretro-reflective particle. Alternatively, some coatings will improve adhesion of theparticle to other materials or a substrate.-45-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570It is also within the scope of this invention to use the precisely shaped-particles as a loose abrasive slurry. These abrasive slurries typically comprise amixture of precisely shaped particles and a liquid medium. The precisely shapedparticles may further comprise abrasive grit(s), grinding aid(s), filler(s) orlubricant(s). It is also within the scope of this invention that the precisely shapedparticle may comprise binder, abrasive grit and a grinding aid or lubricant. Theabrasive grits, grinding aids and fillers are described above in detail. Examples oflubricants include waxes, metal salts of fatty acids, sulfur based compounds,graphite, molybdenum disulfide, talc, boron nitride, silicones, silicone oils,polyglycols, phosphate esters, silicate esters, neopentyl polyol esters and polyphenylethers, fluorochemicals, mineral oils, combinations thereof and the like. The liquidmedium is generally water (including deionized water, tap water or distilled water)and sometimes organic solvent. Sometimes, the liquid is a mixture of water andother additives such as lubricants, rust inhibitors, coupling agents, anti-foams,anti-bacterial compounds, de-greasing compounds, oils, grinding aids, emusilifledorganic compounds, cutting fluids, soaps, waxes, combinations thereof and the like.The loose abrasive slurry can be used in sandblasting type operations.Alternatively, the loose abrasive slurry can be used in combination with a lap plateor a polishing pad for lapping or polishing applications. The lap plate may be a rigidmaterial such as a metal plate, ceramic plate or the like. The polishing pad may be aflexible material such as a foam pad (including polyurethane foam pads), apolymeric material (e.g., polyamide material, rubber material and the like) and thelike. The polishing pad may also be a composite ofa relatively rigid substrate (e.g.,rigid plastic or metal) and a polyurethane foam bonded to the rigid substrate. Thelap plate and/or polishing pad have a smooth outer surface or alternatively theirouter surface may be textured, patterned or discontinuous.In still another aspect of the invention pertains to a method of refining aworkpiece outer surface. This method comprises the steps of:(a) providing a plurality of precisely shaped abrasive particles, whereinthe precisely shaped abrasive particles comprise a plurality of abrasive grits-46-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570distributed in a binder, and wherein the binder is formed from a binder precursorcomprising a free radically curable resin;(b) providing at least one workpiece, wherein the workpiece has anouter surface;(c) providing a vessel having a chamber capable of receiving at least oneof said workpiece and said plurality of precisely shaped abrasive particles;(d) causing said workpiece to traverse relative to a portion of saidplurality of precisely shaped abrasive particles such that the precisely shapedabrasive particles refine the outer surface of the workpiece.In yet another aspect of the invention pertains to a method of refining aworkpiece outer surface. This method comprises the steps of:(a) providing a production tool having a three—dimensional body whichhas at least one continuous surface, said surface containing at least one openingformed in said continuous surface, said at least one opening providing access to acavity in said three—dimensional body;(b) providing a dispensing means capable of introducing a binderprecursor comprising a thermosetting resin into said at least one cavity through saidat least one opening;(c) providing a means, within a curing zone, for at least partially curingsaid binder precursor;(d) introducing said binder precursor into at least a portion of said atleast one cavity;(e) continuously moving said at least one cavity through said curingzone to at least partially cure said binder precursor to provide a solidified,handleable binder having a shape corresponding to that portion of the cavity intowhich the binder precursor had been introduced;(0 removing said binder from said at least one cavity;(g) converting said binder to form a plurality of precisely shapedparticles;(h) providing a plurality of said precisely shaped particles, wherein theprecisely shaped particles comprise a binder;-47-CA 02264872 1999-02-23W0 98/ 10896 PCT/US96/14570(i) providing at least one workpiece, wherein the workpiece has anouter surface;(j) providing a vessel having a chamber capable of receiving at least one1015202530of said workpiece and said plurality of precisely shaped particles;(k) causing said workpiece to traverse relative to a portion of saidplurality of precisely shaped particles such that the precisely shaped particles refinethe outer surface of the workpiece.It is preferred that these precisely shaped particles fiirther comprise at leastone of the following materials: abrasive grits, lubricants, fillers, grinding aids andcombinations thereof.The vessel may be any suitable container having a chamber therein. Thechamber is a structure capable of receiving the workpiece and the plurality ofprecisely shaped particles and optionally a liquid medium;sufficient room in the chamber for the precisely shaped particles to effectively refinethe workpiece outer surface.The precisely shaped particles, whether the particles are incorporated into anabrasive article or the particles are employed as a loose slurries, can be designed torefine a portion ofthe outer surface ofa workpiece. The term refine means that theparticles will do at least one ofthe following, remove a portion ofthe outer surfaceof the workpiece (e.g., abrading), remove debris (including unwanted material suchas dirt, oil, grease and the like) from the outer surface of the workpiece (e.g.,cleaning), or reduce the surface finish (i.e., scratch depth) in the workpiece (e.g.,polishing or buffing).The present invention can be used to refine a wide range of workpiecesurfaces. These workpiece surfaces include metal (including mild steel, carbonsteel, stainless steel, gray cast iron, titanium, aluminum and the like), metal alloys(copper, brass and the like), exotic metal alloys, ceramics, glass, wood (includingpine, oak, maple, elm, walnut, hickory, mahogany, cherry and the like), wood likematerials (including particle board, plywood, veneers and the like), composites,painted surface, plastics (including thermoplastics and reinforced thermoplastics),stones (including jewelry, marble, granite, and semi precious stones), magnetic-43-There should be 'W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570media, and the like. Additional examples of glass workpieces include glasstelevision screens, eye glass lenses, glass ophthalmic surfaces, windows (includinghome windows, office windows, car windows, air windows, train windows, buswindows and the like), glass display shelves, mirrors and the like.The workpiece may be flat or may have a shape or contour associated withit. More examples of specific workpieces include metal engine components(including cam shafts, crankshafis, engine blocks and the like), hand tools metalforgings, fiber optic polishing, caskets, furniture, wood cabinets, turbine blades,painted automotive components, magnetic media (including rigid disc texturing,floppy discs and the like) and the like.Depending upon the particular refining application, the force at the abradinginterface can range from about 0.01 kg to over 100 kg, typically between 0.1 to10 kg. Also depending upon the application, there may be a liquid present at theinterface between the abrasive article or the loose particles and the workpiece outersurface. This liquid can be water and/or an organic solvent. The liquid may filrthercomprise additives such as lubricants, rust inhibitors, coupling agents, anti-foams,anti-bacterial compounds, degreasing compounds, oils, grinding aids, emusilifiedorganic compounds, cutting fluids, soaps, waxes, combinations thereof and the like.The abrasive article may oscillate at the refining interface during use.The abrasive article can be used by hand or used in combination with amachine. For example, the abrasive article may be secured to a random orbital toolor a rotary tool. At least one or both of the abrasive article and the workpieceouter surface is moved relative to the other.The coated or nonwoven abrasive article may be converted into any formsuch as sheet, disc, continuous length roll, belt and the like. If the abrasive articledoes move relative to the workpiece, then the abrasive article can move in anydesired fashion and this depends largely in part upon the particular refiningapplication. For example, the abrasive article can transit in a back and forth fashion,rotary fashion, circular fashion, spiral fashion, elliptical fashion or a random motionAdditionally the abrasive article can oscillate and/or vibrate duringfashion.polishing.-49-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/ 14570It is also within the scope ofthis invention for the workpiece outer surfaceto remain stationary during refining or alternatively, the workpiece outer surfacemay move relative to the abrasive article during refining. If the workpiece outersurface does move relative to the abrasive article, then the abrasive article can movein any desired fashion and this depends largely in part upon the particular refiningapplication. For example, the workpiece outer surface can transit in a back andforth fashion, rotary fashion, circular fashion, spiral fashion, elliptical fashion or arandom motion fashion. Additionally the workpiece outer surface can oscillateand/or vibrate during refining.It is also within the scope ofthis invention that the precisely shaped particlesmay be used as a sandblasting media. In this aspect, these particles are projected (atrelatively high speeds) at the outer surface ofthe workpiece. The precisely shapedparticles may consist essentially of only binder. Alternatively the precisely shapedparticles may further comprise abrasive grits, fillers, grinding aids, lubricants orcombinations thereof.Additionally, it is within the scope of this invention to use the preciselyshaped particles in a traction control or slip resistant article. For example, theprecisely shaped particles may be bonded to a backing and the resulting tractioncontrol article is secured to a floor, stair(s), step(s), deck, computer mouse pad,walkway, ramp, catwalk, mat and the like. The traction control article may besecured either by a pressure sensitive adhesive, a removable adhesive, hook andloop attachment or by a permanent adhesive. In this mode, this traction controlarticle does appreciably refine the surface that comes into contact with the preciselyshaped particles, but rather the traction control article typically provides anincreased coefficient of friction to reduce any potential slippage. It is also feasiblethat the traction control article essentially have a similar construction to a coatedabrasive article, i.e., a make and size coats. Alternatively, the precisely shapedparticles may be mixed into an adhesive (preferably a flowable adhesive) and thisresulting composition is applied or coated to a floor, stair(s), step(s), deck,computer mouse pad, walkway, ramp, catwalk, mat and the like. After this tractioncontrol composition is applied to a surface, the adhesive is solidified to form the-50-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570traction control article. The precisely shaped particles to be used in a tractioncontrol article may consist essentially of only binder. Alternatively the preciselyshaped particles may further comprise abrasive grits, fillers, lubricants orcombinations thereof. The traction control article containing the precisely shapedparticles may be used in indoor or outdoor applications.It is also within the scope of this invention to use the precisely shapedparticles in a filament or a bristle. The bristle will typically have a diameter fromabout l5 to 2500 micrometers, typically between about 25 to 2000 micrometers andpreferably between 50 to 1500 micrometers. The bristle may have an aspect ratiogreater than about one, preferably greater than about 5 and more preferably greaterthan about l0. A plurality of these bristles are then fabricated together to form abrush. This brush may be a flat brush or a rotary brush. Examples of brushconfigurations are further described in US. Patent Nos. 3,924,286; 4,627,127 and5,016,311.without abrasive grits in these particles. Relative to a bristle, it is preferred that theThese bristles may include the precisely shaped particles, with orparticle size of the precisely shaped particle be less than about 50 micrometers,preferably less than about 25 micrometers. The bristle may be extruded or injectionmolded. A particularly preferred brush construction comprises a flexible basehaving a plurality of unitary bristles. The brush is injection molded thermoplasticmaterial.Various modifications and alterations ofthis invention will become apparentto those skilled in the art without departing from the scope and spirit of thisinvention, and it should be understood that this invention is not to be unduly limitedto the illustrative embodiments set forth herein.The following non-limiting examples will further illustrate the invention. Allparts, percentages, ratios, etc., in the examples are by weight unless indicatedotherwise.The following abbreviations and trade names described below in Table 1were used throughout the examples.-51-CA 02264872 1999-02-23wo 93/10396 PCT/US96/14570Table 1 Material DesignationsDesignation MaterialTMPTA trimethylolpropane triacrylate commercially available fromSartomer, Exton, PA. under the trade designation "Sartomer 351"TATHEIC triacrylate of tris(hydroxy ethyl) isocyanurate commerciallyavailable from Sartomer, Exton, PA. under the trade designation“Sartomer 368”PH1 2-benzyl-2-N,N-dimethylamino-l -(4-morpholinophenyl)-1-butanone, commercially available from Ciba Geigy Companyunder the trade designation "IRGACURE 369"KBF4 Potassium tetrafluoroborate grinding aid particulate having anaverage particle size of about 10 micrometersCRY Sodium aluminum fluoride grinding aid particulate commerciallyavailable from Washington MillsCAO1 Ceramic aluminum oxide abrasive grain comprising alpha alumina,magnesia and rare earth oxide modifiers, commercially availablefrom 3M Company, St. Paul, MN. under the trade designation“32l Cubitron” abrasive grainMSCA 3-methacryloxypropyl—trimethoxy silane coupling agent,commercially available from Union Carbide Corp. under the tradedesignation "A-174"ASF amorphous silica particles having an average surface area of 50m2/g, commercially available from DeGussa Corp. (Richfield Part,NJ), under the trade designation "OX-50"PVC polyvinylchloride, commercially available from Geon Company,Cleveland, Ohio under the trade designation “Geon 103EPF-76”PETA pentaerythritol triacrylate commercially available from Sartomer,Exton, PA. under the trade designation "Sartomer 444"RPR1 a resole phenolic resin having 74% solids inwater/2-ethoxyethanol, sodium hydroxide catalyzed andapproximately 2,000 centipoise viscosity at 25 CRPR2 a resole phenolic resin having 74% solids in water, potassiumhydroxide catalyzed and approximately 2,000 centipoise viscosityat 25 CPI-I2 2,2—dimethoxy-1-2-dlphenyl-l-ethanone, commercially availablefrom Ciba Geigy Company under the trade designation “Irgacure65]”BAO grade 180 brown fused aluminum oxide abrasive grit from Villach,AustriaGUAM a glycoluril aciylamide resin havine pendant alpha, betaunsaturated carbonyl groups; this material was made in a mannersimilar to that described in U.S. Patent No. 5,055,113 Prepation 5DAP diacryloyloxyethylphthalate; this material was made in a mannersimilar to that described in U.S. Patent No. 3,336,418-52-W0 98/ 10896l01520CA 02264872 1999-02-23PCT/US96/ 14570NPGDAExton, PA. Under the trade designation "Sartomer 247”Q2 an antifoam commercially available from Dow Corning under thetrade designation “Q2”CACO3 calcium carbonate filler having an average particle size of about 15micrometersCASIO; calcium silicate filler having an average particle size of 18micrometersWA a wetting agent commercially available from Byk Chemie USA,Wallingford, CT under the trade designation “Disperbyk 1 1 1”The precisely shaped particles were made according to one of the generalprocedures described below. These precisely shaped particles were incorporatedinto a coated abrasive article according to the General Procedure For Making aCoated Abrasive Article described below. The abrasive articles were testedaccording to one ofthe test procedures described below.General Procedure I for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared on the apparatus similar to thatillustrated in FIG. 8, except that an ultrasonic horn was installed on the back side ofthe carrier web. A production tool was provided, in a continuous web form, thatcomprised a series of cavities with specified dimensions. These cavities werearranged in a predetermined order or array such that the production tool wasessentially the inverse of the desired shape and dimensions of the precisely shapedparticles. The production tool was made from a polypropylene thermoplasticmaterial that had been previously embossed by extruding the polypropylene materialover a master tool. The nickel master tool also contained a series of cavities withspecified dimensions and shape. The nickel master tool was made via a cuttingknurl process. The production tool had a pattern of cavities in the form of pyramidshaving square bases and disposed such that the bases were butted up against eachother. The height of the pyramid was about 560 micrometers and the base length ofeach side of the base was about l490 micrometers. The surface of the productionneopentyl glycol diacrylate commercially available from Sartomer,WO 981108961015202530CA 02264872 1999-02-23PCT/U S96/ 14570tool containing the cavities is similar to the segment ofthe production tool shown inFIG. 6.As the production tool left the unwind station at a tension of about 30 psi, a51 micrometer thick polyester film carrier web left a second unwind station. Thepolyester film contained an ethylene acrylic acid copolymer primer. A binderprecursor was applied by means of a knife over roll coater with a fixed gap of about51 micrometer into the cavities of the production tool. The portion of theproduction tool containing the binder precursor was brought into contact with thecarrier web by means of a nip roll that had a nip pressure of about 60 psi. Theportion of the production tool containing the binder precursor and the carrier webwas forced against a mandrel that rotated about an axis. Next, radiation energy wastransmitted through the production tool and into the binder precursor. The sourceof the radiation energy wasifour ultraviolet lamps commercially available fromFusion, Inc. that contained a “D” bulb and operated at 600 Watts/inch(240 watts/cm). Upon exposure to the energy source, the binder precursor wasconverted into a solidified, handleable binder. Both the production tool containingthe solidified, handleable binder and the carrier web were continuously movedthrough the curing zone by means of the mandrel. The carrier web was separatedfrom the production tool containing the binder in the vicinity of a nip roll. Anultrasonic horn (Model number 108 commercially available from Branson) wasplaced directly behind the carrier web. The ultrasonic horn operated. on high andhelped to facilitate the removal of the particles from the carrier web. Next, thecarrier web was rewound on a rewind station at a tension pressure of about 100 psi.This was a continuous process that operated at about 130 feet per minute(40 meters/minute) to 180 feet per minute (55 meters/minute).These particles were removed from the carrier web in a combination twomanners, i.e., as discrete particles or as a sheet of particles. These discrete particlesalso included doublets or triplets ofindividual particles. It was preferred to removethe particles as discrete particles. If 25% or less than the particles were removedfrom the carrier web as sheets of particles, then the resulting particles (includingdiscrete particles and particle sheets) were first screened to separate the discrete-54..W0 98/1089610152025CA 02264872 1999-02-23PCT/U S96/ 14570particles from the particle sheets. Then the particle sheets were ball milled in acement mixer using steel or ceramic slugs. The slugs were one inch (2.54 cm) longby three quarter inch (1.9 cm) diameter. Care was taken during ball milling to avoiddamage to the discrete particles. After ball milling, the particles were screened asecond time. If about 25% or more of the particles were removed from from thecarrier web as sheets of particles, then the resulting particles were ball milled in aAfter ball milling the particles weremanner similar to that described above.screened.General Procedure II for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure I for Preparing Precisely Shaped Particles except for the following thechanges. The process was conducted at 50 feet per minute (15 meters/minute) andthere was only one ultraviolet lamp.General Procedure lll for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure II for Preparing Precisely Shaped Particles except that the dimensions ofthe cavities were different. The height ofthe pyramid was about 330 micrometersand the base length of each side ofthe base was about 860 micrometers.General Procedure IV for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure I for Preparing Precisely Shaped Particles except that there were twoultraviolet lamps and both lamps operated at 600 Watts/inch (240 Watts/cm).-55-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/U S96] 14570General Procedure V for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure IV for Preparing Precisely Shaped Particles except that the dimensions ofthe cavities were different. The height of the pyramid was about 330 micrometersand the base length of each side of the base was about 860 micrometers.General Procedure VT for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure IV for Preparing Precisely Shaped Particles except that the dimensions ofthe cavities were different. The length of the base of the pyramid was about1384 micrometers with equalaterial sides of about 1295 micrometers and the heightof the pyramid was about 530 micrometers. This type of pattern is illustrated inFIG. 1 of U.S. Patent No. 5,152,917. Additionally, the master tool was made via adiamond turning process and not a cutting knurl process.General Procedure Vll for PreparingPrecisely Shaped ParticlesThe precisely shaped particles were prepared in a manner similar to GeneralProcedure I for Preparing Precisely Shaped Particles except for the following thechanges. The dimensions of the cavities were changed such that the length of thebase of the pyramid was about 706 micrometers and the height of the pyramid wasabout 240 micrometers. Additionally, only two ultraviolet lamps were employedand the run speed was increased to 250 feet per minute (76 meters/minute).General Procedure I for PreparingCoated Abrasive ArticlesThe grinding aid precisely shaped particles were incorporated into a coatedabrasive disc having a backing made of vulcanized fibre. These fibre discs wereindividually made and had a diameter of 17.8 cm with a center hole having a-56-W0 98/10896l015202530CA 02264872 1999-02-23PCT/US96/14570diameter of 2.2 cm. The make coat was a conventional calcium carbonate filledresole phenolic resin (48% resin, 52% CaCO_~.). The precisely shaped particles werefirst drop coated into the make coat precursor. Next, grade 50 CAOI abrasive gritswere electrostatically coated over the grinding aid particles and into the make coatat a weight of about 14 grams/disc. The resulting construction was heated forabout 90 minutes at about 88°C to partially cure the resole phenolic resin. Next, asize coat was brushed over the abrasive grits/precisely shaped particles layer. Thesize coat was also a conventional cryolite filled resole phenolic resin (32% resin,68% cryolite). The resulting construction was heated for about 90 minutes at 93°Cand then 12 hours at 100°C to fully cure the resole phenolic resin. The wet makecoat weight was approximately four grams/disc and the wet size coat weight wasapproximately nine to ten grams/disc. The fibre discs were flexed prior to testingand humidified for 7 days at 45% relative humidity.General Procedure I] for PreparingCoated Abrasive ArticlesThe grinding aid precisely shaped particles were incorporated into a coatedabrasive disc having a backing made of vulcanized fibre. These fibre discs wereindividually made and had a .diameter of l7.8 cm with a center hole having adiameter of 2.2 cm. The make coat was a conventional calcium carbonate filledresole phenolic resin (48% resin, 52% CaCO3). The precisely shaped particles werefirst drop coated into the make coat precursor. Next, CAOI abrasive grits wereelectrostatically coated over the grinding aid particles and into the make coat. Theresulting construction was heated for about 90 minutes at about 88°C to partiallycure the resole phenolic resin. Next, a size coat was brushed over the abrasivegrits/precisely shaped particles layer. The size coat was also a conventional cryolitefilled resole phenolic resin (32% resin, 68% cryolite). The resulting constructionwas heated for about 90 minutes at 93°C and then 12 hours at 100°C to fully curethe resole phenolic resin. Following this a conventional potassium tetrafluoroboratefilled epoxy resin supersize was coated over the size coat and subsequently cured.-57-CA 02264872 1999-02-23W0 98/10896 PCTIU S96/ 14570The coating weights for the make coat, size coat and supersize coat wereconventional coating weights for the particular grade of CAOI.General Procedure III for Preparing5 Coated Abrasive ArticlesThe precisely shaped abrasive particles were incorporated into a coatedabrasive article. The method to make the coated abrasive article was done acontinuous basis and the resulting web of coated abrasive was converted into anendless, spliced abrasive belt. The backing was a conventional Y weight polyester10 backing with a sateen weave. This cloth backing was conventionally treated withphenolic and phenolic/latex cloth treatments to enhance the physical characteristicsof the backing. A make coat precursor was applied to the front surface of thebacking. The make coat was a conventional calcium carbonate filled ‘resolephenolic resin (48% resin, 52% CaCO_:) and the make coat coating weight was15 290 grams/square meter. The precisely shaped abrasive particles were drop coatedinto the make coat precursor. The resulting construction was heated for about 60minutes at about 96°C to partially cure the resole phenolic resin. Next, a size coatwas coated over the abrasive particles. The size coat was also a conventionalcryolite tilled resole phenolic resin (48% resin. 52% cryolite). The resulting20 construction was heated for about 120 minutes at 93°C and then 10 hours at 107°Cto fully cure the resole phenolic resin. The resulting coated abrasive articles wereflexed prior to testing.General Procedure IV for Preparing25 Coated Abrasive ArticlesThe precisely shaped abrasive particles were incorporated into a coatedabrasive article. The method to make the coated abrasive article was done acontinuous basis and the resulting web of coated abrasive was converted into anendless, spliced abrasive belt. The backing was a conventional Y weight polyester30 backing with a sateen weave. This cloth backing was conventionally treated withphenolic and phenolic/latex cloth treatments to enhance the physical characteristics_58-W0 98/ 108961015202530CA 02264872 1999-02-23PCT/US96/14570of the backing. A make coat precursor was applied to the front surface of thebacking. The make coat was a conventional calcium carbonate filled resolephenolic resin (48% resin, 52% CaCO_~,) and the make coat wet coating weight wasapproximately 290 grams/square meter. Next, approximatelly 440 grams of grade36 brown fused aluminum oxide was drop coated into the make coat precursor.Following this, approximately 450 grams/square meter of grade 36 CAOI wereelectrostatically coated over the brown aluminum oxide. The resulting constructionwas heated for about 90 minutes at about 88°C to partially cure the resole phenolicresin. Next, a size coat was coated over the abrasive grits. The size coat was also aconventional calcium carbonate filled resole phenolic resin (48% resin, 52% calciumcarbonate) at a wet weight of approximately 380 grams/square meter. After thesize coat precursor was applied, the precisely shaped grinding aid particles weredrop coated into the wet size coat precursor. The resulting construction was heated‘for about 120 minutes at 93°C and then I0 hours at 100°C to fully cure the resolephenolic resin. The resulting coated abrasive articles were flexed prior to testing.Test Procedure IThe coated abrasive disc was first mounted on a beveled aluminum back-uppad and then used to grind the face of a 1.25 cm by 18 cm 1018 mild steelworkpiece. The disc was driven at 5,500 rpm at no load while the portion of thedisc overlaying the beveled edge of the back-up pad contacted the workpiece at aload of about 5.9 kg. The coated abrasive disc contacted the workpiece at anglebetween 6 to 7 degrees. Each disc was used to grind a separate workpiece for oneminute intervals for a total grinding time of 10 minutes. The amount of metalremoved (i.e. total cut) during the entire test was measured. There were twocoated abrasive discs tested per example.Test Procedure I]The coated abrasive material was attached to the periphery of a 36 cm metalwheel. The effective cutting area ofthe abrasive segment was 2.54 cm by 109 cm.This grinding process used was a conventional surface grinding wherein the-59-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/ 14570workpiece was reciprocated beneath the rotating contact wheel with incrementaldownfeeding between each cycle. The grinding was done under a water flood. Theworkpiece abraded by these segments was 1018 steel, 1.27 cm width by 36 cmlength by 7.6 cm height. Abrading was conducted along the 1.27 cm by 36 cm face.The metal wheel speed was 5830 surface feet per minute (1780 surfacemeters/minute). The table speed, at which the workpiece traversed, was20 feet/minute (6 meters/minute). The downfeed increment of the wheel was0.0127 mm/pass of the workpiece. The cross feed was 0.45 inch/pass(1.14 crn/pass).Test Procedure IIIThe coated abrasive was converted into 7.6 cm by 335 cm endless belt andtested on a constant load surface grinder. A pre-weighed, 304 stainless steelworkpiece approximately 2.5 cm by 5 cm by 18 cm was mounted in a holder. Theworkpiece was positioned vertically, with the 2.5 cm 18 cm face facing anapproximately 36 cm diameter 65 Shore A durometer serrated rubber contact wheelwith one on one lands over which was entrained the coated abrasive belt. Theworkpiece was then reciprocated vertically through an l8 cm path at the rate of 20cycles per minute, while a spring loaded plunger urged the workpiece against thebelt with a load of 11.3 kg as the belt was driven at about 2050 meters per minute.Afier one minute elapsed grinding time, the workpiece holder assembly wasremoved and re-weighed, the amount of stock removed calculated by subtractingthe abraded weight from the original weight, and a new, pre—weighed workpieceand holder were mounted on the equipment. The test endpoint was 40 minutes.Test Procedure IVAn endless coated abrasive belt (7.6 cm by 335 cm) was installed on aconstant load surface grinder. The belt rotated over a 51 cm (20 inch) diameteraluminum contact wheel and an idler wheel at about 2580 surface meters perminute. The workpiece being abraded was a 304 stainless steel rod, which had a1.9 cm diameter face and was about 30 cm long. The face of the rod was forced-60-W0 98/108961015202530CA 02264872 1999-02-23PCT/US96/14570into the abrasive belt at a rate of 0. l 8 cm/second for 5 seconds. The test endpointwas when the coated abrasive dulled, i.e., the coated abrasive did not substantiallyabraded the workpiece.Test Procedure VThe abrasive article was converted into a 203 cm by 6.3 cm endless belt andwas installed on a Thompson grinding machine. The effective cutting area of theabrasive belt was 203 cm by 2.54 cm. The workpiece was 304 stainless steel,2.54 cm width by 17.78 cm length by 10.2 cm height and was mounted on areciprocating table. Abrading was conducted along the 2.54 by 17.78 cm face. Theabrading process used was conventional surface grinding wherein the workpiecewas reciprocated beneath the rotating abrasive belt with incremental downfeedbetween each pass. The abrading conditions were: approximately 254 micrometersdownfeed, 7.6 meters/minute table speed, and a belt speed of about 1710 surfacemeters/second. Between two consecutive passes underneath the abrasive belt, theworkpiece was cooled with a water spray (with 1% rust inhibitor). The testendpoint was when the abrasive belt was no longer effectively cutting.Examples 1 through 6 and Comparative Example AThis set of examples compared the abrading performance of a coatedabrasive article (Examples 1 through 6) containing precisely shaped grinding aidparticles to a coated abrasive article (Comparative Example A) that did not containprecisely shaped grinding aid particles. The precisely shaped grinding aid particleswere made according to General Procedure I for Making Precisely ShapedParticles, except for the following changes. For examples 1 through 3, the primedpolyester film was exposed to a corona source that operated at 20% power prior tocoming in contact with the grinding aid precursor composition. The grinding aidslurries were prepared by first mixing together using a high shear mixer theTMPTA, TATHEIC, PH], MSCA and ASF in the amounts (in parts) listed belowin Table 2. Next, the grinding aid (either KBF4 or CRY) was gradually added thebinder precursor to for the grinding aid slurries. Also included in Table 2, was the-6]-CA 02264872 1999-02-23W0 98/10896 PCT/US96I14570amount (in grams/disc) of precisely shaped grinding aid particles that wereincorporated into the coated abrasive article.Table 2 Formulations of Grinding Aid Slurries5 for Examples 1 Through 6Material Ex‘ 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6TMPTA 50 50 50 70 70 70TATHEIC 50 50 50 30 30 30PHI l l 1 l l 1MSCA 1 l 1 1 1 1ASF l 1 I l l 1KBF4 O ,0 O 49 49 49CRY 50.6 50.6 50.6 0 0 0Amount of grinding 2 5 7 2 5 7aid particlesThe coated abrasive articles for Examples I through 6 were made accordingto General Procedure I for Making the Coated Abrasive Article. The coated10 abrasive article for Comparative Example A was made according to GeneralProcedure 1 for Making the Coated Abrasive Article except that the article did notcontain precisely shaped grinding aid particles.The resulting coated abrasive articles were tested according to TestProcedure 1 and the test results can be found in Table 3.15-52-WO 98/10896 PCT/US96/14570Table 3 Test Procedure 1Examples 1 through 6 and Comparative Example AExample Initial Cut (grams) Total Cut (grams)1 44.6 146.92 45.1 1953 44.3 2214 44.1 136.95 50.4 197.86 48.4 208.5A 32.7 1 11.85 It can be seen from the above data, that the addition ofthe precisely shaped101520CA 02264872 1999-02-23particles improved the abrading characteristics ofthe coated abrasive discs.Note that the initial cut was the amount of stainless steel removed in the firstsixty seconds of grinding. These cut values were an average of two coated abrasivediscs.Examples 7 through 13 and Comparative Examples B through EThis set of examples compared the abrading performance of a coatedabrasive article (Examples 7 through 13) containing precisely shaped grinding aidparticles to a coated abrasive article (Comparative Examples B through E) that didnot contain precisely shaped grinding aid particles. Relative to Examples 7, 8, 10,11 and 12 the precisely shaped particles were made according to GeneralProcedure 11 for Making Precisely Shaped Particles. Relative to Examples 9 and 13the precisely shaped particles were made according to General Procedure III forMaking Precisely Shaped Particles. The grinding aid slurries were prepared by firstmixing together using a high shear mixer the 1700 grams of TMPTA, 30 grams ofASF, 60 grams of MSCA, 1350 grams of KBF4, 1550 grams of PVC and22.5 grams of PHI. The coated abrasive articles for Examples 7 through 13 were-53-CA 02264872 1999-02-23WO 98/10896 PCT/US96ll4570made according to General Procedure ll for Making the Coated Abrasive Article.The coated abrasive article for Comparative Examples B through E were madeaccording to General Procedure 11 for Making the Coated Abrasive Article exceptthat the article did not contain precisely shaped grinding aid particles. The grade of5 the CAO1, amount (in grams/disc) of precisely shaped grinding aid particle and theamount (in grams/disc) ofthe CAO1 for example is listedTable 4 Amount of Materials for Examples 7 through 13and Comparative Examples B through E10 Example Grade of CAO1 grinding aid particle CAO1(grams/disc) (grams/disc).B 24 0 367 24 5 23.58 24 2.5 20.5C 36 0 209 36 12 4D 50 0 2110 50 2.5 201 l 50 ‘ 5 14.212 50 7.5 12.2E 80 0 19.513 80 5 15The resulting coated abrasive articles were tested according to TestProcedure 1 and the test results can be found in Table 5.-64-W0 98/108961015CA 02264872 19399-02-23PCT/US96/14570Table 5 Test Procedure IExamples 7 through l3 and Comparative Examples B through EExample Total Cut (grams)B 2647 3028 320C 12]9 333D 15710 196l l 235I2 255E I 1513 120It can be seen from the above data, that the addition ofthe precisely shapedparticles improved the abrading characteristics of the coated abrasive discs.Examples I4 through 28This set of examples compared the abrading performance of a coatedabrasive article (Examples l4 through 29) containing precisely shaped abrasiveparticles of various binder compositions. Listed below in Table 6 are the abrasiveslurry formulations (the amounts are listed in parts by weight) that were used toprepare the precisely shaped abrasive particles. The precisely shaped abrasiveparticles were made according to a procedure listed in Table 7. The preciselyshaped abrasive particles were incorporated into a coated abrasive article accordingto General Procedure III for Making the Coated Abrasive. The precisely shapedabrasive particle weight and size coat weight for a given example is also listed inTable 7.-55-CA 02264872 1999-02-23WO 98/10896 PCT/US96/14570Table 6 Abrasive Slurry Formulations forExamples [4 through 28Material Ex. 14, 15, I6 Ex. 17, 18 Ex. 19 Ex. 20 Ex. 21TATHEIC 516 0 O 0 0TMPTA 1204 1720 1720 0 0PH2 20 20 20 20 20MSCA 60 60 60 60 60ASF 30 60 60 20 20CRY 1200 1200 0 1200 OBAO 4000 4120 4120 3800 3800KBF4 0 O 1200 O 0GUAM 0 0 0 860 860DAP 0 0 O 516 516NPGDA 0 0 O 344 344Q2 0 O O 1.5 1.5CACO3 0 O 0 O 1200CASIO; O O 0 0 0-55-CA 02264872 1999-02-23W0 98/10896 PCT/US96/14570Table 6 Continued Abrasive Slurry Formulations forExamples 14 through 28Nkuefial Ex.22 Ex.23 Ex 24 Ex 25,26 Ex 27,28TATHEKI 0 0 O 0 OTMPTA O 0 0 0 OPH2 20» 26 26 26 26MSCA 60 60 60 60 60ASF 20 0 0 O OCRY 0 0 0 O OIBAC) 3800 3600 3600 3500 3600\VÂ¥\ 0 0 0 1.5 1.5GUAM 860 O O O 0DAP 516 O O 0 ONPGDA 344 0 O 0 OPETVX 0 860 860 1190 860RPRI 0 0 O 689 1 160RPR2 0 1160 1160 O 0()2 1.5 1.5 1.5 1.5 1.5CACO3 O 1200 O O OCASIO; 1200 0 1200 1200 1200-67-CA 02264872 1999-02-23W0 98/10896 PCT/US96ll4570Table 7 Examples 14 through 28General Procedure for Abrasive ParticleMaking Abrasive weight in Size Weight inExample Particle (grams/square inch) (grams/square inclfi14 IV 0.53 .2515 IV 0.53 .3216 IV 0.53 .4217 V 0.35 .2718 IV 0.53 .3719 IV 0.53 .29920 . IV 0.53 .4121 IV 0.53 .4222 IV 0.53 .4123 IV 0.53 .4224 IV 0.53 .4025 V 0.37 .2726 VI 0.44 .3027 V 0.37 .2628 VI 0.43 .28The coated abrasive belts were tested according, to Test Procedure 11 and5 the test results can be found in Table 8. The total cut is listed in grams of metalremoved.-63-W0 98/1089610CA 02264872 1999-02-23PCT/US96/ 14570Table 8 Test Procedure llExample Total Cut in gramsF 400I4 12015 l42I6 I9017 2ll18 I8019 10820 I5521 13522 15623 18524 3lO25 26826 36727 26528 304Examples 29 through 31 and Comparative Example FThis set of Examples compared a coated abrasive that contained preciselyshaped particles (Examples 29 through 3]) with a coated abrasive that did notcontain a precisely shaped particle. The precisely shaped particles of Example 29were made according to General Procedure VII for Making Precisely ShapedParticles. The precisely shaped particles of Example 30 were made according toGeneral Procedure Vll for Making Precisely Shaped Particles, except that thedimensions of the cavities were changed. For example 30 and 31, the height of thepyramid was about 350 micrometers and the base length of each side of the basewas about 1020 micrometers. The precisely shaped particles of Example 31 were-69-W0 98/ 10896101520CA 02264872 1999-02-23processed at a slower speed, 150 feet per minute (46 meters per minute). Thegrinding aid slurries were prepared by first mixing together using a high shear mixerthe TMPTA, TATHEIC, PHI, MSCA and ASF in the amounts (in parts) listedbelow in Table 9. Next, the grinding aid was gradually added the binder precursorto for the grinding aid slurries.Table 9 Formulations of Grinding Aid Slurriesfor Examples 29 Through 31PCTIUS96/14570Material Ex. 29 Ex. 30 Ex. 31TMPTA 99.01 99.01 99.01PH] 0.99 0.99 0.99MSCA l l 1ASF l l 1KBF4 182 182 OCRY 0 0 136The coated abrasive for Example 29 was made according to General"Procedure IV for Making the Coated Abrasive Article. For example 29, the weightofthe grinding aid particle was approximately 230 grams/square meter.The coated abrasive for Example 30 was made according to GeneralProcedure IV for Making the Coated Abrasive Article, except for the followingchanges. The grinding aid particles were not drop coated into the size coatprecursor. After the size coat precursor was cured, a supersize precursor coatingwas applied over the size coat. The supersize precursor coating was a conventionalcryolite filled phenolic resin. The grinding aid particles were coated into the wetsupersize precursor coating at a weight of approximately 180 grams/square meter.Next, the resulting construction was heated to cure the resin.The coated abrasive for Example 31 was made according to GeneralProcedure IV for Making the Coated Abrasive Article, except for the followingchanges. The grinding aid particles were not drop coated into the wet size coat.-70-WO 98/10896101520CA 02264872 1999-02-23PCT/US96/ 14570The grinding aid particles were drop coated into the make coat precursor at aweight of approximately 1 10 grams/square meter in place of the brown aluminumoxide abrasive grit. Additionally, a conventional supersize precursor coating wasapplied over the size coat and heated to cure the supersize precursor binder. Thesupersize precursor coating was a conventional potassium tetrafluoroborate filledsolvent based epoxy resin.The coated abrasive for Comparative Example F was made according toGeneral Procedure IV for Making the Coated Abrasive Article, except for thefollowing changes. The precisely shaped grinding aid particles were not drop coatedinto the wet size coat precursor. Additionally, a conventional supersize precursorcoating was applied over the size coat and heated to cure the supersize precursorbinder. The supersize precursor coating was a conventional potassiumtetrafluoroborate filled solvent based epoxy resin.The resulting coated abrasives for Examples 29 through 31 andComparative Example F were tested according to Test Procedures 111, IV and V.The test results are listed in Tables 10, 1 l and 12 respectively.Table 10 Test Procedure III.Examples 29 through 3| and Comparative Example FExample Initial Cut (grams) Final Cut (grams) Total Cut (grams)F 113.44 8.68 1316.4429 100.44 14.16 1612.8830 102.72 14.13 1595.7131 121.70 17.15 1910.44-7]-CA 02264872 1999-02-23W0 98/10896 PCT/U S96/ 14570Table 11 Test Procedure IV.Examples 29, 30 and 3| and Comparative Example FExample Total Cut (grams)F 68129 49930 55531 6265 Table 12 Test Procedure V.Examples 29, 30 and 31 and Comparative Example FExample Total Cut (grams)F 266429 228 l30 257431 2672The above grinding data indicated that different levels of abrading10 performance could be achieved with different grinding conditions.Examples 32 through 40This set of examples demonstrated different grinding aid particulates thatwere incorporated into the precisely shaped grinding aid particle. The formulations15 of the compositions to form the precisely shaped grinding aid particles for this set ofexamples are listed in Table 13.CA 02264872 1999-02-23W0 98/10896 PCT/US96/14570Table I3 Formulations of Grinding Aid Slurriesfor Examples 32 Through 40Material Ex. 32 Ex. 33 Ex. 34 Ex. 35 Ex. 36TMPTA 28 31 57 37 37PH] 0.57 0.8 0.58 0.74 0.74KBF4 17.9 0 0 31.13 0CRY 17.9 17.05 0 O 31.13FES* 0 17.05 0 0 0PVC 0 O 42.24 31.13 31.135 Table 13 Formulations of Grinding Aid Slurries (Continued)for Examples 32 Through 40Material Ex. 37 Ex, 38 Ex. 39 Ex. 40TMPTA 29 99.01 99.01 99.01PHI 0.28 0.99 0.99 0.99KBF4 0 182 182 182CRY 70.72 0 O 0FES* 0 0 0 0PVC 0 O 0 0*FES was an iron sulfide grinding aid (FeS2).10 The precisely shaped grinding aid particles for Examples 32 and 37 weremade in the same manner as Example 31, except that the run speed was 100 feet perminute (30.5 meters/minute).The precisely shaped grinding aid particles for Examples 33 were made inthe same manner as Example 31, except that the run speed was 50 feet per minute15 (16 meters/minute).The precisely shaped grinding aid particles for Examples 34, 35 and 36 weremade in the same manner as Example 31, except that the run speed was 100 feet per-73-W0 98/ 108961015CA 02264872 1999-02-23PCT/US96l 14570minute (30.5 meters/minute). Additionally, the particles as they were removed fromthe carrier web tended to come offin sheets, rather than in discrete particles. Thesesheets were ball milled to convert the sheets into discrete particles.The precisely shaped grinding aid particles for Examples 38 were made inthe same manner as Example 29, except that the carrier web was 50 micrometerthick polyester film and the corona treater level was 25%. Additionally, the runspeed was changed to 150 feet per minute (46 meters/minute).The precisely shaped grinding aid particles for Examples 39 were made inthe same manner as Example 30, except that the carrier web was 50 micrometerthick polyester film and the corona treater level was 25%. Additionally, the runspeed was changed to I00 feet per minute (31 meters/minute).The precisely shaped grinding aid particles for Examples 40 were made inthe same manner as Example 39, except that the dimensions of the particles were‘different. The particles were square based pyramids that had a height of about 560micrometers and the base length of each side was about 1490 micrometers.-74-

Claims (42)

Claims:

1. A coated abrasive article, comprising:
(a) a backing having a front and back surface;
(b) a make coat present on the front surface of the backing;
(c) an abrasive layer bonded to the make coat on the backing, wherein the abrasive layer is characterized by either (i) a plurality of abrasive grits and a plurality of precisely shaped grinding aid particles, wherein the precisely shaped grinding aid particles comprise a binder and a plurality of grinding aid particulates, wherein the precisely shaped grinding aid particles occupy from about 5 to 90 percent of thesurface area in the abrasive layer, and wherein the precisely shaped grinding aid particles have a size ranging from about 0.1 to about 500 micrometers; or (ii) a plurality of precisely shaped abrasive particles bonded to the front surface of the backing by means of said make coat, wherein the precisely shaped abrasive particles comprise a plurality of abrasive grits, distributed in a binder, wherein the binder is formed from a binder precursor comprising a blend of a resole phenolic resin and a free radical curable resin, and wherein the weight ratio between the resole phenolic resin and the free radical curable resin ranges from between about 20 to 60 parts by weight phenolic resin to between about 20 to 60 parts by weight free radical curable resin; and (d) a size coat present over the abrasive layer.

2. A coated abrasive article according to claim 1, wherein the precisely shaped grinding aid particles occupy about 20 to 40 percent of the surface area in the abrasive layer.

3. A coated abrasive article according to claim 1, wherein the abrasive grits are selected from the group consisting of fused aluminum oxide, ceramic aluminum oxide, heat treated aluminum oxide, silicon carbide, alumina zirconia, diamond, ceria, cubic boron nitride, garnet, and combinations thereof.

4. A coated abrasive according to claim 1, wherein the precisely shaped grinding aid particles have shapes selected from the group consisting of pyramids, cones, prisms, spheres, and ellipsoids.

5. A coated abrasive according to claim 1, wherein the precisely shaped grinding aid particles are triangular-based pyramids.

6. A coated abrasive according to claim 1, wherein the precisely shaped grinding aid particles are quadrilateral-based pyramids.

7. A coated abrasive article according to claim 1, wherein the binder for the precisely shaped grinding aid particles is formed from a binder precursor selected from the group consisting of acrylated urethane resins, acrylated epoxyresins, ethylenically unsaturated resins, aminoplast resins having pendant unsaturated carbonyl groups, isocyanurate derivatives having at least one pendant acrylate group and isocyanate derivatives having at least one pendant acrylate group.

8. A coated abrasive article according to claim 1, wherein the binder precursor for the precisely shaped abrasive particles further comprises a free radical initiator.

9. A coated abrasive article according to claim 1, wherein the precisely shaped grinding aid particles further comprise at least one additive selected from the group consisting of fillers, fibers, antistatic agents, lubricants, wetting agents, surfactants, pigments, dyes, coupling agents, plasticizers, and suspending agents.

10. A coated abrasive article according to claim 1, wherein the precisely shaped grinding aid particles comprise from 5 to 95% by weight grinding aid particulates and from 95 to 5% by weight binder.

11. A coated abrasive article according to claim 1, wherein the precisely shaped grinding aid particles comprise from 30 to 75% by weight grinding aid particulates and from 25 to 70% by weight binder.

12. A coated abrasive article according to claim 1, wherein the grinding aid particulate is selected from the group consisting of: sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, magnesium chloride, and combinations thereof.

13. A coated abrasive article according to claim 1, wherein the make coat is selected from the group consisting of phenolic resins, epoxy resins, urea-formaldehyde resins, acrylate resins, acrylated epoxy resins, acrylated urethane resins, aminoplast resins having pendant alpha, beta unsaturated carbonyl groups, maleimide resins, and urethane resins.

14. A coated abrasive article according to claim 1, wherein the size coat is selected from the group consisting of phenolic resins, epoxy resins, urea-formaldehyde resins, acrylate resins, acrylated epoxy resins, acrylated urethane resins, aminoplast resins having pendant alpha, beta unsaturated carbonyl groups, maleimide resins, and urethane resins.

15. A coated abrasive article according to claim 1, wherein the backing is selected from the group consisting of paper, nonwoven substrates, polymeric film, primed polymeric film, cloth, vulcanized fiber, combinations thereof, and treated versions thereof.

16. A coated abrasive article according to claim 1, wherein the weight ratio between the resole phenolic resin and the free radical curable resin ranges from between about 20 to 60 parts by weight phenolic resin to between about 20 to 60 parts by weight free radical curable resin.

17. A coated abrasive according to claim 1, wherein the precisely shaped abrasive particles have a size ranging from about 0.1 to about 2500 micrometers.

18. A coated abrasive according to claim 1, wherein the precisely shaped abrasive particles have a size ranging from about 0.1 to about 500 micrometers.

19. A coated abrasive according to claim 1, wherein the precisely shaped abrasive particles have shapes selected from the group consisting of pyramids, cones, prisms, spheres, and ellipsoids.

20. A coated abrasive article according to claim 1, wherein the precisely shaped abrasive particles further comprise at least one additive selected from the group consisting of fillers, fibers, antistatic agents, lubricants, wetting agents, surfactants, pigments, dyes, coupling agents, plasticizers, and suspending agents.

21. A coated abrasive article according to claim 1, wherein the precisely shaped abrasive particles comprise from 5 to 95% by weight abrasive grits and from 95 to 5% by weight binder.

22. A coated abrasive article according to claim 1, wherein the precisely shaped abrasive particles comprise from 25 to 75 percent by weight abrasive grits and from 25 to 75 percent by weight binder.

23. A coated abrasive article according to claim 1, wherein the backing is selected from the group consisting of paper, nonwoven substrates, polymeric film, primed polymeric film, cloth, vulcanized fiber, combinations thereof, and treated versions thereof.

24. A bonded abrasive article comprising a bonding medium characterized by either:
(a) a plurality of precisely shaped abrasive particles, wherein the precisely shaped abrasive particles comprise a plurality of abrasive grits, distributed in a binder, and wherein the binder is formed from a binder precursor comprising a blend of a resole phenolic resin and a free radical curable resin, and wherein the bonding medium forms a shaped mass of the precisely shaped abrasive particles; or (b) a plurality of abrasive grits and a plurality of precisely shaped grinding aid particles, wherein the precisely shaped grinding aid particles comprise a binder and a plurality of grinding aid particulates, wherein the volume percent of the precisely shaped grinding aid particles ranges from about 5 to 85percent, and wherein the bonding medium serves to form a shaped mass of the abrasive grits and precisely shaped grinding aid particles.

25. A bonded abrasive article according to claim 24, wherein the weight ratio between the resole phenolic resin and the free radical curable resin ranges from between about 10 to 90 parts by weight phenolic resin to between about 10 to 90 parts by weight free radical curable resin.

26. A bonded abrasive article according to claim 24, wherein the weight ratio between the resole phenolic resin and the free radical curable resin ranges from between about 20 to 60 parts by weight phenolic resin to between about 20 to 60 parts by weight free radical curable resin.

27. A bonded abrasive according to claim 24, wherein the size of the precisely shaped abrasive particles have a size ranging from about 0.1 to about 2500 micrometers.

28. A bonded abrasive according to claim 24, wherein the size of the precisely shaped abrasive particles have a size ranging from about 0.1 to about 500 micrometers.

29. A bonded abrasive according to claim 24, wherein the precisely shaped abrasive particles have shapes selected from the group consisting of pyramids, cones, prisms, spheres, and ellipsoids.

30. A bonded abrasive article according to claim 24, wherein the binder precursor further comprises a free radical initiator.

31. A bonded abrasive article according to claim 24, wherein the precisely shaped abrasive particles comprise from 5 to 95% by weight abrasive grits and from 95 to 5% by weight binder.

32. A bonded abrasive article according to claim 24, wherein the bonding material is selected from the group consisting of phenolic resins, epoxyresins, urea-formaldehyde resins, acrylate resins, acrylated epoxy resins, acrylated urethane resins, aminoplast resins having pendant alpha, beta unsaturated carbonyl groups, maleimide resins, and urethane resins.

33. A bonded abrasive article according to claim 24, wherein the volume percent of the precisely shaped grinding aid particles ranges from about 5 to 75 percent.

34. A bonded abrasive according to claim 24, wherein the precisely shaped grinding aid particles have a size ranging from about 0.1 to about 2500 micrometers.

35. A bonded abrasive according to claim 24, wherein the precisely shaped grinding aid particles have a size ranging from about 0.1 to about 500 micrometers.

36. A bonded abrasive according to claim 24, wherein the precisely shaped grinding aid particles are triangular-based pyramids.

37. A bonded abrasive according to claim 24, wherein the precisely shaped grinding aid particles are quadrilateral-based pyramids.

38. A bonded abrasive article according to claim 25, wherein the binder for the precisely shaped grinding aid particles is formed from a binder precursor selected from the group consisting of acrylated urethane resins, acrylated epoxyresins, ethylenically unsaturated resins, aminoplast resins having pendant unsaturated carbonyl groups, isocyanurate derivatives having at least one pendant acrylate group and isocyanate derivatives having at least one pendant acrylate group.

39. A bonded abrasive article according to claim 24, wherein the binder precursor for the precisely shaped abrasive particle further comprises a free radical initiator.

40. A bonded abrasive article according to claim 24, wherein the precisely shaped grinding aid particles comprise from 5 to 95% by weight grinding aid particulates and from 95 to 5% by weight binder.

41. A coated abrasive article according to claim 1, wherein the grinding aid particulate is selected from the group consisting of: sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, magnesium chloride, and combination thereof.

42. A method of making a coated abrasive article according to claim 1, comprising the steps of:
(a) providing a backing having a front and back surface;
(b) applying a make coat precursor over the front surface of the backing;
(c) at least partially embedding a plurality of abrasive grits into the make coat precursor;
(d) converting the make coat precursor into a make coat;
(e) applying a size coat precursor over the abrasive grits, the size coat precursor comprising a bonding medium;
(f) at least partially embedding a plurality of precisely shaped grinding aid particles into the size coat precursor, wherein the precisely shaped grinding aid particles have a size ranging from about 0.1 to about 500 micrometers;
and (g) exposing the backing, make coat, abrasive grit and size coat precursor to conditions such that the size coat precursor is converted into a size coat and a coated abrasive article is formed.