CA1293862C - Coated abrasive products employing nonabrasive diluent grains - Google Patents
Coated abrasive products employing nonabrasive diluent grainsInfo
- Publication number
- CA1293862C CA1293862C CA000603558A CA603558A CA1293862C CA 1293862 C CA1293862 C CA 1293862C CA 000603558 A CA000603558 A CA 000603558A CA 603558 A CA603558 A CA 603558A CA 1293862 C CA1293862 C CA 1293862C
- Authority
- CA
- Canada
- Prior art keywords
- grains
- nonabrasive
- coated abrasive
- abrasive
- abrasive article
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
- B24B3/18—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of taps or reamers
- B24B3/20—Tapering or chamfering taps or reamers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Polishing Bodies And Polishing Tools (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A coated abrasive article comprised of a blend of premium abrasive grains and nonabrasive diluent grains adhered to a backing material by a resinous binder. The article has an unexpected abrading efficiency, performing equal to, or superior to, a coated abrasive article containing only premium abrasive grains.
A coated abrasive article comprised of a blend of premium abrasive grains and nonabrasive diluent grains adhered to a backing material by a resinous binder. The article has an unexpected abrading efficiency, performing equal to, or superior to, a coated abrasive article containing only premium abrasive grains.
Description
6~
, . :
F.N. 41820 CAN 8A
COATED P.BRASIVE PRODUCTS
-EMPLOYIt1G NONABRASIVE DII,UE:NT GRAINS
.
; Technical Field The present invention relates to coated abrasive product which contain~ both abrasive grains and nonabrasive diluent grains and to a method of making the sa~e.
Background Art Coated abrasives typically consist of a backing substrate, abrasive grains, and a bonding system which operates to hold the abrasive grains to the backing. In a lS typ~cal coated abrasive product, the backing is Eirst coated with a layer of adhesive, commonly referred to as a "make coat"/ and then the abrasive grains are applied. The resulting adhe~ive/abrasive composite layer is then generally solidified or set enough to retain the abrasive grains to the backing, so that a second layer of adhe~ive, ; commonly referred to as a "size coat'i, can be applied. The size~coat further reinforces the coated abra6ive product upon setting. Optionally/ a "supersize coat", which may contai~n grinding aids, an be applied over the solidified ~size coat. Once the size coat and supersize coat, if used, has cured, the resulting coated abrasive product can be formed into a variety of convenient articles such as sheets, rolls, helts and discs.
The backing substrate used in coated abrasive 30 ~ products is typically chosen from ~aper, polymeric fiJm, cloth, vulcanized fiber, nonwoven web, combinations :
thereof, or treated versions of these. Commonly used abrasive grains include ~lint, garnet, emery, silicon carbide, fused aluminum oxide, ceramic aluminum oxide, : :
: 35 ~ ~k ' ~ ' - .
-~6Z
fused alumina-zirconia, fused zirconia, diamonds, multl-grain granules. Conventional bond systems typically comprise a glutinous or resillous adhesive such as hide glue, phenolic, epoxy, acrylate, melam;.ne, urethane, urea-formaldehyde or mixtures thereof. Fillers are sometimesadded to the adhesive to reduce the cost and to improve the cured resin's he~t stability and hardness.
For many years fused aluminum oxide and silicon carbide were the primary abrasive grains used in coated abrasives. This has been changed somewhat by the development of "premium" abrasive grains such as fused alumina-zirconia (commercially available from the Norton Company o~ Worcester, Mass. under the trade designation NorZon) and alpha alumina-based ceramic materials ~commercially available from the 3M Company of St. Paul, MN
under the trade designation Cubitronn). Coated abrasive products containing these premium abrasive grains generally perform better in stock ~emoval applications than coated abrafiive products containing fused aluminum oxide or sllicon carbide. Fused alumina-zirconia and alpha alum~na-based ceramic mate~ials are not universally used in coated abrasives, however, due to their high cost ~n comparison to fused aluminum oxide and silicon carbide.
Thus, an incentive exists to reduce the cost of coated 2~ abrasive products csntaining these premium abrasives without ~acrificing their performance.
The present invention achieves this goal by using premium a~raslve grains in combination with nonabrasive inorganic diluent grains whose Knoop hardness is le~s than 200. The addition of the diluent grain provide~ a coated abrasive product o lower cost having equal or improved performance when compared to a coated abrasive product comprised only of the premium abrasive grains.
The blending of two or more types of grains to reduce the cost and/or to improve the performance of an 3~29~3~
abrasive article is well known in the art. Examples disclosing such blending include:
U.S. Patent No. 2,410,506, Kirchner et al, which discloses a coated abrasive article wherein an expensive diamond abrasive grit is diluted with relatively inexpensive silicon carbide abrasive grits.
Assignee's European patent application, EP
228,856 published July 15, 1'3B7, which discloses blendin~ abrasive grits formed of ceramic-conta~ning oxides of alumin~m and yttrium with less expensive conventional abrasive grits or materials which are not noted as abrasive, such as marble, glass and the like, in an abrasive product to reduce cost.
U.S. Patent No. 3,175,894, Foot, which di6closes a bonded abrasive article comprised of an admixture of used alumina abrasive particles and fused zirconia abrasive particles. The combination of the two grains is reported to produce an abrasive article having performance characteristics superior to articles made of either fused alumina or fused zirconia alone.
;~ Additionally, diluting the expensive fused zirconia with less expensive fused alumina abrasive grains lowers the cost of the abrasive article.
U.S. Patent No. 1,830,757, Hartmann, which discloses abrasive articles, both bonded and ~ coated, compri~ed of a mi~ture of abrasive particles having a Moh's hardness of 9 or greater and friable nonabrasive particles having a Moh's hardness below g. The nonabrasive particles reportedly may be any particles of a granular nature that are more friable than th~ abrasive ~ grains and yet firm enough to break out of the :
3~
bonded mass without glazing the surface of the article, or that do not ~orm as firm a union wlth the bond adhesive as do the abrasive particles.
During grinding, the friable grains are said to break apart and leave holes or depressions over the grinding face which results in an open, sharp-cutting surface that improves the abrasive action.
U.S. Patent No. 3,476,537, Markotan, which discloses abrasive articles, both bondsd and coated, in which porosity has been induced by the addition, to the abrasive composition, o a granular agent approximating the abrasive grains in size but softer than the abrasive grains. ~he porosity inducing agent is preferably one that is widely available at very low cost, as compared with that of the abrasive grit material. The ; porosity inducing agent reportedly may be selected from limestone, natural or activated bauxits, and minerals such as olivin~, gypsum, ~ chromite, coquimbite, pyrolusite, molybdenite,; ~ ~ galena, halite and the like, as well as a variety of products~manufactured for a simllar purpose.
It is noted that the materials re~erred to above vary quite widely in hardness on the Moh and Knoop scales, i.e., from Moh' Nos. 1~3 to as high as 6 or 7. These improved abrasive products reportedly will remove more stock than, or at lea~t as much a6, a conventional product.
U. S . ~Patent No. 3,996,702, Leahy, which discloses a coated abrasive product using fused zirconia as the abrasive. It is considered desirable,~however, to include a substantial portion of alumina abrasive grains or other diluent to reduce the cost of the product without ~ ` unduly reducing perormance. The alumina grains ,' .
~ :
;~2~3~
can either be blended with zirconia grains or, fused alumina-zirconia grains may be ~ormed by crushing hardened fused blencls of alu~ina and zirconia. If desired, softel grains such as flint, which function in a manner analogous to a filler or diluent, reportedly may be blended with fused zirconia containing grzlins.
U.S. Patent No. 3,266,878, Timmer et al., which discloses a coated abrasive product wherein 1~ diamond abrasive is diluted with an abrasive material capable of being formed into discrete particles and having a ~oh's hardnes6 withln the range from 4~0 to 8.5. The dilution of the diamond abrasive reportedly increases the out of lS the abrasive surEace and reduces the cost o~ the abra,,ive article.
Canadian Patent No. 802,150, publlshed February 11, 1964, Cadwell, which discloses a coated abrasive product comprising diamond abrasive granules diluted with granules having a Knoop hardness in the range from 200 to 650.
Examples of this invention reportedly removed three times more stock per carat o~ diamond consumed than conventional diamond articles such as described in Kirchner et al. discu sed above.
U.S. Patent No. 4,734,104, Broberg, and U.S.
Patent No. ~,737,163, Larkey, which disclose coated abrasive products wherein the abrasive ~ grains comprise a mixture of expensive "superior"
;~ ~ 30 abrasive grain~, such as co-fused alumina-zi~conia, and alpha alumina~based ceramic grains, with other abrasive grains such as fused alumina. The superior abrasive grains were - concentrated in the coarse fraction of the ; 35 abrasive grain grading sequence while the other abrasive grains were concentrated in the ine .
8~2 fraction. Reportedly, the addition oE the ~uperior abrasive grains improved abrading performance significantly more than would be expected, with products containing the blend of grains performing superiorly, in some case6, to products made with either abrasive grain alons.
It should be clear at this point that Applicant does not contend that he has been the fi~6t to incorporate lC nonabrasive i~organic diluent grains having a Knoop hardnes6 less than 200 into an abrasive article. Markotan discloses abras~ve articles wherein known abrasives are diluted with granular materials such as limestone and gypsum. Rather, the invention is primarily concerned with the unexpected discovery that blending premiu~ abrasive gralns with nonabrasive inorganic diluent grains having a Knoop hardness less than 20~, in a coated abrasive product, not only lowers the cost of the article, but does so without reducing the article's performance.
~; 20 The benefit of a reduced article cost without a corre6ponding reduction in performance for coated abrasive products containing nonabrasive inorganic dilu~nts selected from the class having a ~noop hardness less than 200 is unexpected in view of the state of the art. The prior art ; 25 appears to limit the class of diluents capable of providing this benefit in coated abrasive articles to diluents having greater hardness. For example, Cadwell limits the diluents to those having a Knoop hardness in the range from 200 to 650 and Timmer et al. limit the diluents to those having a ~oh's hardness from 4.0 to 8.5. Thus, the art teaches away rom the use o~ diluents having a Knoop hardness less khan ~ ~ 200 to achieve this benefit in coated abrasives.
; Additionally, although coated abrasive products containing diluents within this class are included within the disclosures of Hartmann and Markotan, these two patents dQal primarily with bonded abrasive products. In fact, all '' :
~, --7~
o the examples disclosed in these two patents showing improved or equal performance by abrasive products containing these diluents used bonded abrasive wheels.
However, due to the difference in mode of operation between bonded and coated abrasives, improved or equal performance in coated abrasive articles would not be expected to follow directly from the improved performance attributable to the incorporation of these diluents in bonded abrasives.
~onded abrasives rely upon the continual breakdown and removal of the abrasive grains on the cutting surface to continually present sharp cutting points to the material being ground. The soft nonabrasive diluents improve the performance of bonded abrasives since they breakdown quickly during the grinding action and leave holes or depre~sions over the grinding face, which aid the breakdown of the abrasive grains and help maintain a sharp-cutting grinding surface. Coated abrasives, on the other hand, have only a single layer of abrasive grains. ~hus, adding soft nonabrasive diluents, which breakdown quickly under grlnding action and aid the breakdown of the abrasive grains, to coated abrasives, would be expected to lead to the removal of the entire cutting surface, thereby reducing the life and performance of the abrasive article.
The present invention provides coated abrasive articles having excellent abrading effectiveness, utilizing the advantages inherent in premium abrasive grains, while minlmizing the quantity of such grains actually employed.
In~eed, in some instances synergistic effects are obtained, the construction actually performing better than coated abrasive products in which only the premium abraslve is present.
The present invention provides a coated abrasive article comprising a blend of premium abra~ive grains and nonabrasive inorganic diluent grains adhered to a backing ~3~
material. As used herein inorganic diluent grains include both individual grains of inorganic diluent and multigrain aggregates of inorganic diluent bound together by means such as fusing, or binders. Binders used to form these multigrain aggregates can be either organic or inorganic.
The nonabrasive inorganic diluent grains have a Knoop hardness less than 200. Useful examples of such nonabrasive diluents include marble, marl, travertine, chalk, coral, coquina, oolite, and gypsum, with marble and gypsum being pre~erred. The premium abrasive grains useful ln the present invention include alpha alumina-based ceramic materials, fused alumina-zirconia, refractory coat~d silicon carbide, diamond, cubic boron nitride, and combinations thereof. The preferred premium abrasive gra~ns are fused alumina-zirconia and alpha alumina-based ceramics.
The incorporation of the nonabrasive inorganic diluent grains into the coated abrasive artlcle of the present invention endows the abrasive article with an unexpected abrading efficiency when compared to a similar coated abrasive containing a full loading of premium abrasive grain~ Coated abrasive articles of the present invention have abrading efficiencies equal to, or superior to, th~ abrading efficiencies of undiluted coated abrasive articles containing a full loading of premium abrasive grains, despite the drastically reduced proportion of abra~ive grains in the coated abrasive article of the present invention. Additionally, since the nonabrasive diluent grains are generally less expensive than the premium abrasive grains, the coated abrasive articles of the present invention are less expensive than coated abrasive articles containing a full loading of premium abrasive grains with no diluent.
3~362 g DETAILED DESCRIPTION
The coated abrasive products of the present invenklon generally include conventional backings and binders and a premium abrasive material which is diluted with a nonabrasive inorganic diluent. Materials used in abrasive articles are often categorized according to their ablllty to abrade a surface. Materials capable o quickly abrading a surface being denoted "premium" while those that ; abrade a surface slowly, or not at all, are denoted "nonabrasive". The designation as premium or nonabrasive involves a considerable degree of subjectivity, and depends to some degree on the type of workpiece and the abrading conditions employed. Nevertheless, for most commercially ~ignificant abrading operations, it has been found that a test involving the abrasion of cold rolled steel with coated abrasive products having only one type o grain, will, when compared to an identical construction involving a di~ferent grain, yield test results which are highly reliable in categorizing abrasives as premium or nonabrasive.
To classi~y materials commonly used in abrasive article~ as premium or nonabrasive, abra~ive di6cs containing Grade 36 abrasive grains (average grain size of 710 ~icrome~ers) were prepared. Conventional coated abrasive making procedures were followed using conventional 0.76 mm thick vulcanized Eiber backings, a conventional calcium carbonate-filled phenolic resin make coat, and a conventional cryolite-filled phenolic resin size coat. The make coat weight was 170 g/m2. ~he make resin was precured for 90 minutes at 88C and the size resin precured for 90 minutes at B8C followed by final curing at 100C for 10 hours. The coatings were applied via conventional techn;ques in a one-trip operation and were cured in a forced air oven. The cured 17.8 cm diameter discs were conventionally flexed to controllably break the hard ; bonding resins, mounted on a beveled aluminum back-up pad, 3~36~2 , ~
and u~ed tG grind a 1.25 cm by 18 cm face o~ a 1018 cold rolled steel workpiece. The disc was driven at 5,500 rpm while the portion of the disc overlying the ~eveled edge of the back-up pad contacted the workpiece at a load of 5.91 kg. Grinding was conducted for one minute time intervals and each disc was u~ed to grind a separate workpi~ce ~or a total of 12 minutes or until no more than 5 grams o metal were removed in any one minute grinding cut, whichever came fir~t. ThiS te6t was performed for different discs, each di~c containing undiluted grains of one of the following materials: fused alumina-zirconia, ceramic aluminum oxide, heat-treated fused aluminum oxide, brown fused aluminum oxide, garnet, and marble. The total amount of metal ttotal cut) removed by using such discs can be found ln Table 1, along with the mineral and size coating weights.
In each case, the total cut figure is the average for at least three discs.
TAsLE 1 .
Coating Wei~ht Grain Designation Grain SizeTotal Cut . .
(g/m2) ~g/m2)(g) Fused alumina-zirconia 920 700 969 - 25 C~ramic aluminum oxide1060 700 1411 Heat treated aluminum oxide 900 530 329 Brown fu~ed aluminum oxide 1060 700 371 G~rnet 1270 700 209 Marble 530 540 22 If the total cut of a coated abrasive disc is greater than 500 grams, the abrasive grain is con~idered premium. ~f the total cut of a coated abrasive disc is less than 50 grams, the grain is considered nonabrasive.
Typically, nonabrasive diluent grains will cut considerably les~ than S0 grams. The stock removal of 1018 steel by nonabrasive diluent grains is not attributed to its cutting power but solely to the mechanical friction o the workpiece rubbing against the nonabrasive diluent grains.
:~2~
The nonabrasive diluent grains defined above should not be confused with the abrasive grains denoted "inferior" in U.S. Patent No. 4,734,104 and U.S. Patent No.
, . :
F.N. 41820 CAN 8A
COATED P.BRASIVE PRODUCTS
-EMPLOYIt1G NONABRASIVE DII,UE:NT GRAINS
.
; Technical Field The present invention relates to coated abrasive product which contain~ both abrasive grains and nonabrasive diluent grains and to a method of making the sa~e.
Background Art Coated abrasives typically consist of a backing substrate, abrasive grains, and a bonding system which operates to hold the abrasive grains to the backing. In a lS typ~cal coated abrasive product, the backing is Eirst coated with a layer of adhesive, commonly referred to as a "make coat"/ and then the abrasive grains are applied. The resulting adhe~ive/abrasive composite layer is then generally solidified or set enough to retain the abrasive grains to the backing, so that a second layer of adhe~ive, ; commonly referred to as a "size coat'i, can be applied. The size~coat further reinforces the coated abra6ive product upon setting. Optionally/ a "supersize coat", which may contai~n grinding aids, an be applied over the solidified ~size coat. Once the size coat and supersize coat, if used, has cured, the resulting coated abrasive product can be formed into a variety of convenient articles such as sheets, rolls, helts and discs.
The backing substrate used in coated abrasive 30 ~ products is typically chosen from ~aper, polymeric fiJm, cloth, vulcanized fiber, nonwoven web, combinations :
thereof, or treated versions of these. Commonly used abrasive grains include ~lint, garnet, emery, silicon carbide, fused aluminum oxide, ceramic aluminum oxide, : :
: 35 ~ ~k ' ~ ' - .
-~6Z
fused alumina-zirconia, fused zirconia, diamonds, multl-grain granules. Conventional bond systems typically comprise a glutinous or resillous adhesive such as hide glue, phenolic, epoxy, acrylate, melam;.ne, urethane, urea-formaldehyde or mixtures thereof. Fillers are sometimesadded to the adhesive to reduce the cost and to improve the cured resin's he~t stability and hardness.
For many years fused aluminum oxide and silicon carbide were the primary abrasive grains used in coated abrasives. This has been changed somewhat by the development of "premium" abrasive grains such as fused alumina-zirconia (commercially available from the Norton Company o~ Worcester, Mass. under the trade designation NorZon) and alpha alumina-based ceramic materials ~commercially available from the 3M Company of St. Paul, MN
under the trade designation Cubitronn). Coated abrasive products containing these premium abrasive grains generally perform better in stock ~emoval applications than coated abrafiive products containing fused aluminum oxide or sllicon carbide. Fused alumina-zirconia and alpha alum~na-based ceramic mate~ials are not universally used in coated abrasives, however, due to their high cost ~n comparison to fused aluminum oxide and silicon carbide.
Thus, an incentive exists to reduce the cost of coated 2~ abrasive products csntaining these premium abrasives without ~acrificing their performance.
The present invention achieves this goal by using premium a~raslve grains in combination with nonabrasive inorganic diluent grains whose Knoop hardness is le~s than 200. The addition of the diluent grain provide~ a coated abrasive product o lower cost having equal or improved performance when compared to a coated abrasive product comprised only of the premium abrasive grains.
The blending of two or more types of grains to reduce the cost and/or to improve the performance of an 3~29~3~
abrasive article is well known in the art. Examples disclosing such blending include:
U.S. Patent No. 2,410,506, Kirchner et al, which discloses a coated abrasive article wherein an expensive diamond abrasive grit is diluted with relatively inexpensive silicon carbide abrasive grits.
Assignee's European patent application, EP
228,856 published July 15, 1'3B7, which discloses blendin~ abrasive grits formed of ceramic-conta~ning oxides of alumin~m and yttrium with less expensive conventional abrasive grits or materials which are not noted as abrasive, such as marble, glass and the like, in an abrasive product to reduce cost.
U.S. Patent No. 3,175,894, Foot, which di6closes a bonded abrasive article comprised of an admixture of used alumina abrasive particles and fused zirconia abrasive particles. The combination of the two grains is reported to produce an abrasive article having performance characteristics superior to articles made of either fused alumina or fused zirconia alone.
;~ Additionally, diluting the expensive fused zirconia with less expensive fused alumina abrasive grains lowers the cost of the abrasive article.
U.S. Patent No. 1,830,757, Hartmann, which discloses abrasive articles, both bonded and ~ coated, compri~ed of a mi~ture of abrasive particles having a Moh's hardness of 9 or greater and friable nonabrasive particles having a Moh's hardness below g. The nonabrasive particles reportedly may be any particles of a granular nature that are more friable than th~ abrasive ~ grains and yet firm enough to break out of the :
3~
bonded mass without glazing the surface of the article, or that do not ~orm as firm a union wlth the bond adhesive as do the abrasive particles.
During grinding, the friable grains are said to break apart and leave holes or depressions over the grinding face which results in an open, sharp-cutting surface that improves the abrasive action.
U.S. Patent No. 3,476,537, Markotan, which discloses abrasive articles, both bondsd and coated, in which porosity has been induced by the addition, to the abrasive composition, o a granular agent approximating the abrasive grains in size but softer than the abrasive grains. ~he porosity inducing agent is preferably one that is widely available at very low cost, as compared with that of the abrasive grit material. The ; porosity inducing agent reportedly may be selected from limestone, natural or activated bauxits, and minerals such as olivin~, gypsum, ~ chromite, coquimbite, pyrolusite, molybdenite,; ~ ~ galena, halite and the like, as well as a variety of products~manufactured for a simllar purpose.
It is noted that the materials re~erred to above vary quite widely in hardness on the Moh and Knoop scales, i.e., from Moh' Nos. 1~3 to as high as 6 or 7. These improved abrasive products reportedly will remove more stock than, or at lea~t as much a6, a conventional product.
U. S . ~Patent No. 3,996,702, Leahy, which discloses a coated abrasive product using fused zirconia as the abrasive. It is considered desirable,~however, to include a substantial portion of alumina abrasive grains or other diluent to reduce the cost of the product without ~ ` unduly reducing perormance. The alumina grains ,' .
~ :
;~2~3~
can either be blended with zirconia grains or, fused alumina-zirconia grains may be ~ormed by crushing hardened fused blencls of alu~ina and zirconia. If desired, softel grains such as flint, which function in a manner analogous to a filler or diluent, reportedly may be blended with fused zirconia containing grzlins.
U.S. Patent No. 3,266,878, Timmer et al., which discloses a coated abrasive product wherein 1~ diamond abrasive is diluted with an abrasive material capable of being formed into discrete particles and having a ~oh's hardnes6 withln the range from 4~0 to 8.5. The dilution of the diamond abrasive reportedly increases the out of lS the abrasive surEace and reduces the cost o~ the abra,,ive article.
Canadian Patent No. 802,150, publlshed February 11, 1964, Cadwell, which discloses a coated abrasive product comprising diamond abrasive granules diluted with granules having a Knoop hardness in the range from 200 to 650.
Examples of this invention reportedly removed three times more stock per carat o~ diamond consumed than conventional diamond articles such as described in Kirchner et al. discu sed above.
U.S. Patent No. 4,734,104, Broberg, and U.S.
Patent No. ~,737,163, Larkey, which disclose coated abrasive products wherein the abrasive ~ grains comprise a mixture of expensive "superior"
;~ ~ 30 abrasive grain~, such as co-fused alumina-zi~conia, and alpha alumina~based ceramic grains, with other abrasive grains such as fused alumina. The superior abrasive grains were - concentrated in the coarse fraction of the ; 35 abrasive grain grading sequence while the other abrasive grains were concentrated in the ine .
8~2 fraction. Reportedly, the addition oE the ~uperior abrasive grains improved abrading performance significantly more than would be expected, with products containing the blend of grains performing superiorly, in some case6, to products made with either abrasive grain alons.
It should be clear at this point that Applicant does not contend that he has been the fi~6t to incorporate lC nonabrasive i~organic diluent grains having a Knoop hardnes6 less than 200 into an abrasive article. Markotan discloses abras~ve articles wherein known abrasives are diluted with granular materials such as limestone and gypsum. Rather, the invention is primarily concerned with the unexpected discovery that blending premiu~ abrasive gralns with nonabrasive inorganic diluent grains having a Knoop hardness less than 20~, in a coated abrasive product, not only lowers the cost of the article, but does so without reducing the article's performance.
~; 20 The benefit of a reduced article cost without a corre6ponding reduction in performance for coated abrasive products containing nonabrasive inorganic dilu~nts selected from the class having a ~noop hardness less than 200 is unexpected in view of the state of the art. The prior art ; 25 appears to limit the class of diluents capable of providing this benefit in coated abrasive articles to diluents having greater hardness. For example, Cadwell limits the diluents to those having a Knoop hardness in the range from 200 to 650 and Timmer et al. limit the diluents to those having a ~oh's hardness from 4.0 to 8.5. Thus, the art teaches away rom the use o~ diluents having a Knoop hardness less khan ~ ~ 200 to achieve this benefit in coated abrasives.
; Additionally, although coated abrasive products containing diluents within this class are included within the disclosures of Hartmann and Markotan, these two patents dQal primarily with bonded abrasive products. In fact, all '' :
~, --7~
o the examples disclosed in these two patents showing improved or equal performance by abrasive products containing these diluents used bonded abrasive wheels.
However, due to the difference in mode of operation between bonded and coated abrasives, improved or equal performance in coated abrasive articles would not be expected to follow directly from the improved performance attributable to the incorporation of these diluents in bonded abrasives.
~onded abrasives rely upon the continual breakdown and removal of the abrasive grains on the cutting surface to continually present sharp cutting points to the material being ground. The soft nonabrasive diluents improve the performance of bonded abrasives since they breakdown quickly during the grinding action and leave holes or depre~sions over the grinding face, which aid the breakdown of the abrasive grains and help maintain a sharp-cutting grinding surface. Coated abrasives, on the other hand, have only a single layer of abrasive grains. ~hus, adding soft nonabrasive diluents, which breakdown quickly under grlnding action and aid the breakdown of the abrasive grains, to coated abrasives, would be expected to lead to the removal of the entire cutting surface, thereby reducing the life and performance of the abrasive article.
The present invention provides coated abrasive articles having excellent abrading effectiveness, utilizing the advantages inherent in premium abrasive grains, while minlmizing the quantity of such grains actually employed.
In~eed, in some instances synergistic effects are obtained, the construction actually performing better than coated abrasive products in which only the premium abraslve is present.
The present invention provides a coated abrasive article comprising a blend of premium abra~ive grains and nonabrasive inorganic diluent grains adhered to a backing ~3~
material. As used herein inorganic diluent grains include both individual grains of inorganic diluent and multigrain aggregates of inorganic diluent bound together by means such as fusing, or binders. Binders used to form these multigrain aggregates can be either organic or inorganic.
The nonabrasive inorganic diluent grains have a Knoop hardness less than 200. Useful examples of such nonabrasive diluents include marble, marl, travertine, chalk, coral, coquina, oolite, and gypsum, with marble and gypsum being pre~erred. The premium abrasive grains useful ln the present invention include alpha alumina-based ceramic materials, fused alumina-zirconia, refractory coat~d silicon carbide, diamond, cubic boron nitride, and combinations thereof. The preferred premium abrasive gra~ns are fused alumina-zirconia and alpha alumina-based ceramics.
The incorporation of the nonabrasive inorganic diluent grains into the coated abrasive artlcle of the present invention endows the abrasive article with an unexpected abrading efficiency when compared to a similar coated abrasive containing a full loading of premium abrasive grain~ Coated abrasive articles of the present invention have abrading efficiencies equal to, or superior to, th~ abrading efficiencies of undiluted coated abrasive articles containing a full loading of premium abrasive grains, despite the drastically reduced proportion of abra~ive grains in the coated abrasive article of the present invention. Additionally, since the nonabrasive diluent grains are generally less expensive than the premium abrasive grains, the coated abrasive articles of the present invention are less expensive than coated abrasive articles containing a full loading of premium abrasive grains with no diluent.
3~362 g DETAILED DESCRIPTION
The coated abrasive products of the present invenklon generally include conventional backings and binders and a premium abrasive material which is diluted with a nonabrasive inorganic diluent. Materials used in abrasive articles are often categorized according to their ablllty to abrade a surface. Materials capable o quickly abrading a surface being denoted "premium" while those that ; abrade a surface slowly, or not at all, are denoted "nonabrasive". The designation as premium or nonabrasive involves a considerable degree of subjectivity, and depends to some degree on the type of workpiece and the abrading conditions employed. Nevertheless, for most commercially ~ignificant abrading operations, it has been found that a test involving the abrasion of cold rolled steel with coated abrasive products having only one type o grain, will, when compared to an identical construction involving a di~ferent grain, yield test results which are highly reliable in categorizing abrasives as premium or nonabrasive.
To classi~y materials commonly used in abrasive article~ as premium or nonabrasive, abra~ive di6cs containing Grade 36 abrasive grains (average grain size of 710 ~icrome~ers) were prepared. Conventional coated abrasive making procedures were followed using conventional 0.76 mm thick vulcanized Eiber backings, a conventional calcium carbonate-filled phenolic resin make coat, and a conventional cryolite-filled phenolic resin size coat. The make coat weight was 170 g/m2. ~he make resin was precured for 90 minutes at 88C and the size resin precured for 90 minutes at B8C followed by final curing at 100C for 10 hours. The coatings were applied via conventional techn;ques in a one-trip operation and were cured in a forced air oven. The cured 17.8 cm diameter discs were conventionally flexed to controllably break the hard ; bonding resins, mounted on a beveled aluminum back-up pad, 3~36~2 , ~
and u~ed tG grind a 1.25 cm by 18 cm face o~ a 1018 cold rolled steel workpiece. The disc was driven at 5,500 rpm while the portion of the disc overlying the ~eveled edge of the back-up pad contacted the workpiece at a load of 5.91 kg. Grinding was conducted for one minute time intervals and each disc was u~ed to grind a separate workpi~ce ~or a total of 12 minutes or until no more than 5 grams o metal were removed in any one minute grinding cut, whichever came fir~t. ThiS te6t was performed for different discs, each di~c containing undiluted grains of one of the following materials: fused alumina-zirconia, ceramic aluminum oxide, heat-treated fused aluminum oxide, brown fused aluminum oxide, garnet, and marble. The total amount of metal ttotal cut) removed by using such discs can be found ln Table 1, along with the mineral and size coating weights.
In each case, the total cut figure is the average for at least three discs.
TAsLE 1 .
Coating Wei~ht Grain Designation Grain SizeTotal Cut . .
(g/m2) ~g/m2)(g) Fused alumina-zirconia 920 700 969 - 25 C~ramic aluminum oxide1060 700 1411 Heat treated aluminum oxide 900 530 329 Brown fu~ed aluminum oxide 1060 700 371 G~rnet 1270 700 209 Marble 530 540 22 If the total cut of a coated abrasive disc is greater than 500 grams, the abrasive grain is con~idered premium. ~f the total cut of a coated abrasive disc is less than 50 grams, the grain is considered nonabrasive.
Typically, nonabrasive diluent grains will cut considerably les~ than S0 grams. The stock removal of 1018 steel by nonabrasive diluent grains is not attributed to its cutting power but solely to the mechanical friction o the workpiece rubbing against the nonabrasive diluent grains.
:~2~
The nonabrasive diluent grains defined above should not be confused with the abrasive grains denoted "inferior" in U.S. Patent No. 4,734,104 and U.S. Patent No.
4,737,163. The designation as a "superior" or "inferior"
abrasive in these two references is a relative measurement between two different abrasive grain types. I a coated abrasive product containing one type of abrasive grain cuts over 10~ more than an identical coated abrasive product containing a diferent type of abrasive grain, under identical test conditions, then the first type of abrasive grain is deemed "superior" and the second type "inferior".
Thus, the designation as "superior" or "lnferiorl' is a characteristic of the pair of abrasive grain types compared, not a measurement of the ultimate abrasiveness of the abrasive grain type so designated. The abrasive grain typas denoted "in~erior" are abrasive nonetheleæs and differ, therefore, from the nonabrasive diluent grains defined above.
Premium abrasive grains useful in the present invention include alpha alumina-based ceramio materials such as those disclosed in U.3. Patents 4,314,~27, 4,518,397, 4,574,003, 4,623,364, 4,744,802 and EP
publication 228,856; fused alumina-zirconia such as disclosed in U.S. Patents 3,781,172, 3,~91,40~ and 3,893,826; refractory coated silicon carbide such as disclosed in U.S. Patent 4,505,720; diamond; cubic boron nitride and combinations thereof.
The nonabrasive inor~anic diluent grains used in the present invention have a hardness less than 200 on the Knoop hardness scale. Typical nonabrasive diluent grains of the invention include limestone and gypsum. Limestone encompasses a whole family of materials whose chemical compo~ition is primarily calcium carbonate. Limestone type materials use~ul in the present invention range from lithographic limestone, whieh is a very fine, even grain variety, to an oolite limestone, which is a coarse rock composed of tiny spherical bodies. Useful materials falling within the limestone ~amily include marble, marl, travertine, chalk, coral, coquina ancl oolite. The limestone type ~aterial preferred in the practice of thls invention is marble (typically consi~;ting of about 99%
calcium carbonate).
Gypsum,~ calcium sulfate dehydrate, CaSO4 2H2O, is another nonabrasive diluent grain useful in the present invention. It is known for its softrless, having MOH's hardne~s between 1.5 and 2Ø Gypsum is available as a natural mineral or as a synthetic by-product of chemical proce~ses 6uch a~ phosphoric acid synthesis, t~tanium oxide synthesi~, citric acid synthesis and stack gas scrubhlng.
The natural mlneral is rarely found in pure form and typically contains calcium carbonate, magnesium carbonate, silica, clay minerals and a variety of soluble ~alts.
The nonabrasive inorgAnic diluent grains o~ the invention should not be con~used with organic diluent~ or inorganic ~illers which are sometimes used in the bond system of coated abrasives. The nonabrasive inorganic diluent grain is significantly larger than inorganic fillers and is a part of the grain layer, not a part of the bond~system.
~ Typically, very soft materials do not function a6 abrasive grains. Thus, the discovery that coated abrasives containing blends of premium abrasive grains with so~t nonabrasive diluent grains exhibit abrading characteristics equal to, or superior to, coated abrasives containing only pre~ium abrasive grains, or blends of premium abrasive grains with other abrasive grains, is unexpected. Even more unexpected, however, is the discovery of the amount by which the premium abrasive grains can be diluted without a reduction in abrading characteristics. It has been found that a ratio as high as 95 parts of nonabrasive diluent 3S g~ains to 5 parts premium abrasive grains by volume produ~e~ a coated abrasive that performs equal to, or superior to, one containing 10n% premium abrasive grains.
3~6~
This re6ult is unexpected since only a minor portion of the total amount of grains, i.e., the premium grains, is actually abrading the workpiece. The preferred range of diluent grains is from about 50~ to about 80% by volume based on a total volume of 100% of all grain. ~owever, coated abrasives containing less than 50% by volume nonabrasive diluent grains still have performance characteristics equal to, or superior to, ones containing lQ0% premium abrasive grains.
The nonabrasive inorganic diluent grains are generally less expensive than conventional abra~ive~ such a~ ~used aluminum oxide and silicon carbide, and significantly less expensive than premium grains such as ~used alumina-zirconia and alpha alumina-based ceramic materials. Thus, the coated abrasives of the present invention are less expensive than coated abrasives made with 10~ premium abrasive grain. In some cases the cost o~ a coated abrasive article of the present invention is equal to, or less than, the cost o~ a coated abrasive article made of conventional abrasive geains, while having an abrading efficiency equal to, or superior to, a coated abrasive article made of premium abrasive grains. The `~ actual costs are difficult to predict, however, due to changing market condltions.
The process for making the coated abrasive product of the invention is essentially the same as what is currently known in the art. The make adhesive coat is applied to the backing, followed by the addition of the grains. The premium abrasive grains and the nonabrasive diluent grains can either be hlende~ together and coated as a single layer or coated in separate layers. In the blending method, the two grains are charged to a mixer and blended; then the grains are electrostatically coated. In the ~econd method, the nonabrasive diluent grains are drop coated onto the make adhesive coat and the premium abrasive grains are electrostatically coated on top of the diluent , a3~62 grains. After the addition of the grains, the make coat is solidl~ied enough to secure the grains to the backing in order for the size adhesive coat to be applied. After sizing, the adhesive is solidified and an optional supersize adhesive, which ~ay contain a grinding ald, can be applied.
Grinding aids, or active fillers, may also be added to the size coat or as a particulate material. The pre~erred gr~nding aid is potassium fluoroborate, although other grind~ng aids such as sodium chloride, sulfur, pota~sium titanium fluoride~ polyvinyl chloride, polyvinylidene chloride, cryolite, and combinations thereof, are also believed to be useful. The preferred amount of grinding aid is on the order of 50 to 300, prePerably 80 to 160, grams per square meter o coated abrasive product.
The preferred coated abrasive construction comprises a polyester cloth backing, a calcium : carbonate-~illed resole phenolic resin as the make coat, fused alumina-zirconia or alpha alumina-ba~ed ceramic materials as the premium abrasive grains, gypsum as the nonabrasive diluent grain, a cryolite-filled resole phenolic resin as the size coat and a potassium ~luoroborate-filled epoxy resin as a supersize coat. The preferred volume ratio of premium abrasive grains to nonabrasive diluent grains ranges from 90:10 to 5:95, and more pre~erably from 50:50 to 20:80.
The invention is further illustrated by the ~ollowing nonlimiting examples wherei~ :all part~ and ~ 30 percentages are by volume unless otherwise stated.
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:~ EX~MPLES
: The following examples describe the various components and steps that were used to fabricate the invention. The coating weights of the make coat, the : abrasive grains, the size coat, and the supersize coat are all ln grams per square meter unless otherwise specified.
3~
5rw: WO~EN Y WEIG~T POLYESTESR ~ACKING. The coated abrasive backing used was a Y weight woven polyester cloth with a four over one weave. The backing was saturated with a lat~x/phenolic resin and then placed in an oven to partially cure the resin. Next, a calcium carbonate-filled latex/phenolic resin coating was applied to the ~ackside of the backing and the coated backing was heated to 120C and maintained at this temperature until the resin had cured to a tack-free state. Finally, a eoating of latex/phenolic resin wa~ applied to the coat ~or front) side of the coated backing and the coated backing was heated to 120C and maintained at this temperature until the resin had cured to a tack-free state. The backing was now completely treated and was ready to receive the make coat.
XW: WOVEN X WEIGHT POLYBSTER ~ACKINGo The coated abrasive backing used was an X weight woven palyester cloth with a ~our over one weave. The backing was prepared in the same manner as described above for the Y weight woven polyester backing. ~fter the backing was completely treated, it was ready to receive the make coat.
YS: STITCHBONDED POLYESTER BACKING. The coated abrasive backing used was a Y weight knitted polyester cloth. The treating system for the backing was the same as described above for the woven polyester backing.
MAKE COAT: The make coat was a calcium carbonate filled resole phenolic resin which was diluted with solvent to 84~ solids. The make coat was applied on top of the coated backing to provide an average weight of 280, unless otherwise specified.
After the make coat was applied, the grains were applied as described below. ~he grains were grade 50 ~average particle size of 430 micrometers) according to ANSI standards.
.
BLEND: BLEND OF GR~INS. In this method, the premium abrasive ~rains were blended with the diluent grains in a specified volume ratio. Then the blend was el~ctro~tatically coated.
.
3~il6 ~ AYERS: GR~INS IN SEPARATE LAYERS. In ~his method, the nonabrasive grains were drop coated on to the make coat, then the premium abrasive grains were electrostatically coated.
S
Immediately after the grains were applied, the sub~trate/grain composite was precurled for 90 minute6 in an oven set at 88C. Next, a size coat was applied wh~ch is detailed below.
CCSC. CALCIUM CARBONATE SIZE COAT. This size coat wa~ a calcium carbonate-filled resole phenolic resin dllut~d with solvent to 78~ solids. The average size coat weight was 285, unless otherwise specified.
CRSC: CRYOLITE SIZE COAT. ThiS size coe,t was a cryolite-~llled resole phenolic resin diluted with solvent to a 76~ solids. The average size coat weight was 285, unless otherwise specified.
~0 KBFSC: POT~SSIUM FLUOROBORATE SIZE COAT. This ~ize coat was potassium fluoroborate-filled epoxy/a~ine curvative resin diIuted with solvent to 72% solids. The average size~coat weight was 155, unless otherwise Specified, A ter size coating, the coated abrasive material rec~ived a precure of 90 ~inutes at 88C and then a final cure of 10 hours at 100C. The coated abrasive material was then flexed.
SUPERSIZE COAT. The supersize coat is an optional coat that is applied over the size coat. It comprised potassium fluoroborate as a grinding aid in an epoxy/amine curvative resin. ~he average supersize coat ~:: we~ght was 155. It was cured in an oven at 8~C for 90 minutes .
~2~3~62 The coated abrasive material was then converted into endless belts which were tested for abrasiveness, as described ln the following test procedure. A pre-weighed, 6tainless steel workpiece (SAE 304) approximately 2.5 x 5 x 18 cm, mounted in a holder, was positioned vertically, with th~ 2.5- x 18- cm face confronting an approximately 36-cm diameter 85 Shore A durometer serrated rubber contact wheel with one on one lands over which was entrained a belt to be te~ted. The workpiece was then reciprocated vertically through an 18 cm path at the rate of 20 cycles per minute, wh~le a spring-loaded plunger urged the workpLece against the belt with a load of 13.6 kg, as the belt was driven at about 2050 meters per minute. After one ~inute of elap~ed grlnding time, the workpiece-holder assembly was removed and reweighed, the amount of stock removed calculated by subtracting the abraded weight from khe original weight, and a new, pre-weighed workpiece and holder was mounted on the equipment.
Examples 1 through 3 ~ Examples l through 3 compare coated abrasives `~ having decreasing ratios of aluminum oxide to marble. The aluminum ox~de was heat treated and is not considered to be a premium abrasive grain. The marble, which is the same marble used in the rest of the examples, was purchased under the trade designation Carthaqe Marble from JM Huber Corp. The backing was XW, the grains were blended together, and the size coat was KBFSC with an average weight of 270. The cut data is reported in Table 2; with the total cut being the amount of material removed in 20 minute~ of grin~ing.
'' ~3~6;~
Tab1e 2 Comparison o~ different ratios of a nonpremium abrasive grain to a nonabrasive diluent grain.
Volume Ratio Grain Total Cut ExampleAluminum Oxide/Marble Wei~ht (grams) ... . . _ .
2 50/50 5~0 639 It can be seen from the above data that as the amount of nonabrasive diluent grain was increa~ed from 25 lS volume percent to 75, and the amount of the nonpremium abrasive grain decreased, the performance decreased.
Examples 4 and 5 Examples 4 and 5 compare the abrasive performance of a coated a~rasive containing 100~ aluminum oxide abrasive grain to one containing a blend oP aluminum oxide abrasive grains with marble diluent grains. The aluminum oxide was fused brown aluminum oxide and is not considered to be a premium abrasive grain. The backing was YW, the grains were blended toqether and the size coat was KBFSC.
The make coat weight was 245, grain weight was 612 and the si~e coat weight was 294. The cut data corresponding to 20 minutes of ~rinding is reported in Table 3.
;.
Table 3 Comparison of different ratios of a nonpremium abrasive grain to a nonabrasive diluent grain.
Volume Ratio Cut Example Aluminum Oxide/Marbl_ (grams) 4 lQ0/~ 854 75/25 ~55 ~2~31~2 These examples demonstrate essentially the same performance, despite the removal o~ 25~ of the abrasi~e grain and its replacement with the nonabrasive marble diluent.
Examples 6_throu~7h_9 Examples 6 through 9 compare coated abrasives o~
the invention having decreasing ratios of ceramic based aluminum oxide containing yttrium oxide premi~m abrasive grain to a marble nonabrasive diluent grain. The premium abrasive grain was made according to European patent application EP 228,856, published July 15, 1987. The backing was XN, the grains were blended together and the ~iæe coat was KBFSC. The grinding was terminated when the 15 flnal cut was approximately less than 60 grams per minute.
The coating weights and test data are reporte~ in Tables 4 and 5, respectively.
Table 4 : ~0 Coating Weights Make Grain Size 6 226 ~24 297 : 7 24~ 561 3û6 8 . 243 566 28i ~ :, Table 5 Comparison of different ratios of a premium ~: 30abrasive grain to a nonabrasive diluent grainO
Volume Ratio Cut ~ Example Premium~Grains/Diluent Grains (grams) : 6tcontrol) 100/0 1295 7 75/25 1~42 .. 8 50/50 1542 9 25/75 162g ~, `:
3 ~ 6 It can be seen ~rom the above data that the abrasive performance increased as the amount of pre~ium abrasive grains replaced by nonabrasive diluent grains increased.
: 5 Examples_10 throu~h 15 .
Examples 10 through 15 compare coated abrasives having decreasing ratios of fused alumina-zirconia premium ~ abrasive grain to gypsum nonabrasive diluent grain. The i 1~ gypsum wa6 industrial gypsum purchased from US Gyp~um and is the same gypsum used in the remainder of the examples.
The backing was YS, the grains were blended togeth~er, and the ~ize coat was CRSC. The make coat weight was 335 and the size coat weight was 286. Grinding wa~ terminated when : 15 the final cut was less than 35 grams in sixty seconds. The cut data is reported in Table 6.
: Table 6 : Comparison between different ratios of : 20 alumina zirconia and gypsum.
. Volume Ratio Grain Total Cut Alumina-Zirconia/Gypsum Welght ~
10 . lO0/0 712 4g5 25 11 :80/20 63~ 6~8 12 60/40 60~ 756 I4 20/80 4~0 1034 In this set of examples the optimum nonabrasive~
: diluent loading is approximatel~ 80% by volume. It is surprising and unexpected that a coated abrasive having only 20~ premium abrasive grain cut over twice as much as a ~ ~35 coated abrasive having 100% premium abrasive gr~in.
``:
~L~9;~362 Examples 16 and 17 Examples 16 and 17 compare the abra~ive per~ormance of grade 50 coated abrasives containing a blend of premium abrasive grains and nonabrasive diluent grains, the abrasive and diluent grains being mixed together and applied as a single layer in one, versus the grains being applied as separate layers in the other. The volume ratio of the fused alumina-zirconia premium abrasive grain to the marble nonabrasive diluent grain was 60:40. The backing w~s YW, the size coat was CRSC and a supersize coat was applied. The grinding test was terminated when the final cut was less than 40 grams in slxty seconds. The coating weights and grinding data are reported in Table 7.
Table 7 Grains ~lended vs. Grains in Separate Layers.
Coating Weights Total Cut 20 Ex~mpleMake Grain Size Supersize (~r~ms) 16 blend 210 557 356 13~ 2330 17 layer~ 281 637 289 159 2617 A performance increase of 12% is shown when the premium abrasive grains and nonabrasive diluent grains are applied in ~eparate layers rather than being blended together and applied as a single layer.
ExamE~s 18 and 19 T~e6e examples compare the coated abrasive performance using marble, versus gypsum, as the nonabrasive diluent in combination with fused alumina-zirconia as the premium abrasive grain. Examples 18 and 19 were fabricated and tested in the same manner as Example 17. Example 18 conta~ned marble as the nonabrasive diluent ~rain and , ~
~LZ~3~36~
.
Example 19 contained gypsum as the nonabrasive diluent : grain. The coating weights and cut results are reported in Table 8.
Table 8 ; Comparison of Marble vs. Gyp6um 10as the Nonabra~ive Diluent Grain Coating Weiyhts Total Cut ExampleMake Grain Size Supersize (grams) 1~ marble210 557 356 123 2330 15lg 9ypsum ld9 507 306 96 2605 A performance increase of 12% is shown when gypsum i8 the nonabrasive diluent grain rather than marb1e.
Examples 20 through 25 : Examples 20 through 25 co~pare the abrasive performance of coated abrasives made using a blend of fuæed alumina-zirconia as the premium abrasive grains with : several diluent:grains of various hardnesses. The backing was YW and the size coat was CCSC. The blend of grains comprised 80% by volume diluent grains and 20% by volume fused alumina-zirconia. The coating weights, nonabrasive diluent~, and the cut data are reported in Table 9. The ~ri~ding test was terminated when the stock removed in 60 ~econds was less than 30 gra~s. A control having no ~ diluent grains is provided ~or comparison.
,:~
:. 35 ' ~2~93~
: Tabl e 9 Comparison of Different Diluents.
Coating Weights Total Cut 5Example Diluent Make Grain Size (~rams) Control 201 708 335 665 21 Gypsum 205 532 285 671 22 Pumice 201 708 218 279 23 Garnet 189 440 253 463 24 Emeey 195 520 226 478 - 25 ~rown 205 532 243 452 Al203 It can be Seen f rom this data that gypsur~ was the be8t diluent grain tested, .' ~
', :
;~ 20 , :
:
~.~ 25 ~: : :
:
: , 3 0 '' ~ 35 :
:'~
. ,
abrasive in these two references is a relative measurement between two different abrasive grain types. I a coated abrasive product containing one type of abrasive grain cuts over 10~ more than an identical coated abrasive product containing a diferent type of abrasive grain, under identical test conditions, then the first type of abrasive grain is deemed "superior" and the second type "inferior".
Thus, the designation as "superior" or "lnferiorl' is a characteristic of the pair of abrasive grain types compared, not a measurement of the ultimate abrasiveness of the abrasive grain type so designated. The abrasive grain typas denoted "in~erior" are abrasive nonetheleæs and differ, therefore, from the nonabrasive diluent grains defined above.
Premium abrasive grains useful in the present invention include alpha alumina-based ceramio materials such as those disclosed in U.3. Patents 4,314,~27, 4,518,397, 4,574,003, 4,623,364, 4,744,802 and EP
publication 228,856; fused alumina-zirconia such as disclosed in U.S. Patents 3,781,172, 3,~91,40~ and 3,893,826; refractory coated silicon carbide such as disclosed in U.S. Patent 4,505,720; diamond; cubic boron nitride and combinations thereof.
The nonabrasive inor~anic diluent grains used in the present invention have a hardness less than 200 on the Knoop hardness scale. Typical nonabrasive diluent grains of the invention include limestone and gypsum. Limestone encompasses a whole family of materials whose chemical compo~ition is primarily calcium carbonate. Limestone type materials use~ul in the present invention range from lithographic limestone, whieh is a very fine, even grain variety, to an oolite limestone, which is a coarse rock composed of tiny spherical bodies. Useful materials falling within the limestone ~amily include marble, marl, travertine, chalk, coral, coquina ancl oolite. The limestone type ~aterial preferred in the practice of thls invention is marble (typically consi~;ting of about 99%
calcium carbonate).
Gypsum,~ calcium sulfate dehydrate, CaSO4 2H2O, is another nonabrasive diluent grain useful in the present invention. It is known for its softrless, having MOH's hardne~s between 1.5 and 2Ø Gypsum is available as a natural mineral or as a synthetic by-product of chemical proce~ses 6uch a~ phosphoric acid synthesis, t~tanium oxide synthesi~, citric acid synthesis and stack gas scrubhlng.
The natural mlneral is rarely found in pure form and typically contains calcium carbonate, magnesium carbonate, silica, clay minerals and a variety of soluble ~alts.
The nonabrasive inorgAnic diluent grains o~ the invention should not be con~used with organic diluent~ or inorganic ~illers which are sometimes used in the bond system of coated abrasives. The nonabrasive inorganic diluent grain is significantly larger than inorganic fillers and is a part of the grain layer, not a part of the bond~system.
~ Typically, very soft materials do not function a6 abrasive grains. Thus, the discovery that coated abrasives containing blends of premium abrasive grains with so~t nonabrasive diluent grains exhibit abrading characteristics equal to, or superior to, coated abrasives containing only pre~ium abrasive grains, or blends of premium abrasive grains with other abrasive grains, is unexpected. Even more unexpected, however, is the discovery of the amount by which the premium abrasive grains can be diluted without a reduction in abrading characteristics. It has been found that a ratio as high as 95 parts of nonabrasive diluent 3S g~ains to 5 parts premium abrasive grains by volume produ~e~ a coated abrasive that performs equal to, or superior to, one containing 10n% premium abrasive grains.
3~6~
This re6ult is unexpected since only a minor portion of the total amount of grains, i.e., the premium grains, is actually abrading the workpiece. The preferred range of diluent grains is from about 50~ to about 80% by volume based on a total volume of 100% of all grain. ~owever, coated abrasives containing less than 50% by volume nonabrasive diluent grains still have performance characteristics equal to, or superior to, ones containing lQ0% premium abrasive grains.
The nonabrasive inorganic diluent grains are generally less expensive than conventional abra~ive~ such a~ ~used aluminum oxide and silicon carbide, and significantly less expensive than premium grains such as ~used alumina-zirconia and alpha alumina-based ceramic materials. Thus, the coated abrasives of the present invention are less expensive than coated abrasives made with 10~ premium abrasive grain. In some cases the cost o~ a coated abrasive article of the present invention is equal to, or less than, the cost o~ a coated abrasive article made of conventional abrasive geains, while having an abrading efficiency equal to, or superior to, a coated abrasive article made of premium abrasive grains. The `~ actual costs are difficult to predict, however, due to changing market condltions.
The process for making the coated abrasive product of the invention is essentially the same as what is currently known in the art. The make adhesive coat is applied to the backing, followed by the addition of the grains. The premium abrasive grains and the nonabrasive diluent grains can either be hlende~ together and coated as a single layer or coated in separate layers. In the blending method, the two grains are charged to a mixer and blended; then the grains are electrostatically coated. In the ~econd method, the nonabrasive diluent grains are drop coated onto the make adhesive coat and the premium abrasive grains are electrostatically coated on top of the diluent , a3~62 grains. After the addition of the grains, the make coat is solidl~ied enough to secure the grains to the backing in order for the size adhesive coat to be applied. After sizing, the adhesive is solidified and an optional supersize adhesive, which ~ay contain a grinding ald, can be applied.
Grinding aids, or active fillers, may also be added to the size coat or as a particulate material. The pre~erred gr~nding aid is potassium fluoroborate, although other grind~ng aids such as sodium chloride, sulfur, pota~sium titanium fluoride~ polyvinyl chloride, polyvinylidene chloride, cryolite, and combinations thereof, are also believed to be useful. The preferred amount of grinding aid is on the order of 50 to 300, prePerably 80 to 160, grams per square meter o coated abrasive product.
The preferred coated abrasive construction comprises a polyester cloth backing, a calcium : carbonate-~illed resole phenolic resin as the make coat, fused alumina-zirconia or alpha alumina-ba~ed ceramic materials as the premium abrasive grains, gypsum as the nonabrasive diluent grain, a cryolite-filled resole phenolic resin as the size coat and a potassium ~luoroborate-filled epoxy resin as a supersize coat. The preferred volume ratio of premium abrasive grains to nonabrasive diluent grains ranges from 90:10 to 5:95, and more pre~erably from 50:50 to 20:80.
The invention is further illustrated by the ~ollowing nonlimiting examples wherei~ :all part~ and ~ 30 percentages are by volume unless otherwise stated.
:` ~
:~ EX~MPLES
: The following examples describe the various components and steps that were used to fabricate the invention. The coating weights of the make coat, the : abrasive grains, the size coat, and the supersize coat are all ln grams per square meter unless otherwise specified.
3~
5rw: WO~EN Y WEIG~T POLYESTESR ~ACKING. The coated abrasive backing used was a Y weight woven polyester cloth with a four over one weave. The backing was saturated with a lat~x/phenolic resin and then placed in an oven to partially cure the resin. Next, a calcium carbonate-filled latex/phenolic resin coating was applied to the ~ackside of the backing and the coated backing was heated to 120C and maintained at this temperature until the resin had cured to a tack-free state. Finally, a eoating of latex/phenolic resin wa~ applied to the coat ~or front) side of the coated backing and the coated backing was heated to 120C and maintained at this temperature until the resin had cured to a tack-free state. The backing was now completely treated and was ready to receive the make coat.
XW: WOVEN X WEIGHT POLYBSTER ~ACKINGo The coated abrasive backing used was an X weight woven palyester cloth with a ~our over one weave. The backing was prepared in the same manner as described above for the Y weight woven polyester backing. ~fter the backing was completely treated, it was ready to receive the make coat.
YS: STITCHBONDED POLYESTER BACKING. The coated abrasive backing used was a Y weight knitted polyester cloth. The treating system for the backing was the same as described above for the woven polyester backing.
MAKE COAT: The make coat was a calcium carbonate filled resole phenolic resin which was diluted with solvent to 84~ solids. The make coat was applied on top of the coated backing to provide an average weight of 280, unless otherwise specified.
After the make coat was applied, the grains were applied as described below. ~he grains were grade 50 ~average particle size of 430 micrometers) according to ANSI standards.
.
BLEND: BLEND OF GR~INS. In this method, the premium abrasive ~rains were blended with the diluent grains in a specified volume ratio. Then the blend was el~ctro~tatically coated.
.
3~il6 ~ AYERS: GR~INS IN SEPARATE LAYERS. In ~his method, the nonabrasive grains were drop coated on to the make coat, then the premium abrasive grains were electrostatically coated.
S
Immediately after the grains were applied, the sub~trate/grain composite was precurled for 90 minute6 in an oven set at 88C. Next, a size coat was applied wh~ch is detailed below.
CCSC. CALCIUM CARBONATE SIZE COAT. This size coat wa~ a calcium carbonate-filled resole phenolic resin dllut~d with solvent to 78~ solids. The average size coat weight was 285, unless otherwise specified.
CRSC: CRYOLITE SIZE COAT. ThiS size coe,t was a cryolite-~llled resole phenolic resin diluted with solvent to a 76~ solids. The average size coat weight was 285, unless otherwise specified.
~0 KBFSC: POT~SSIUM FLUOROBORATE SIZE COAT. This ~ize coat was potassium fluoroborate-filled epoxy/a~ine curvative resin diIuted with solvent to 72% solids. The average size~coat weight was 155, unless otherwise Specified, A ter size coating, the coated abrasive material rec~ived a precure of 90 ~inutes at 88C and then a final cure of 10 hours at 100C. The coated abrasive material was then flexed.
SUPERSIZE COAT. The supersize coat is an optional coat that is applied over the size coat. It comprised potassium fluoroborate as a grinding aid in an epoxy/amine curvative resin. ~he average supersize coat ~:: we~ght was 155. It was cured in an oven at 8~C for 90 minutes .
~2~3~62 The coated abrasive material was then converted into endless belts which were tested for abrasiveness, as described ln the following test procedure. A pre-weighed, 6tainless steel workpiece (SAE 304) approximately 2.5 x 5 x 18 cm, mounted in a holder, was positioned vertically, with th~ 2.5- x 18- cm face confronting an approximately 36-cm diameter 85 Shore A durometer serrated rubber contact wheel with one on one lands over which was entrained a belt to be te~ted. The workpiece was then reciprocated vertically through an 18 cm path at the rate of 20 cycles per minute, wh~le a spring-loaded plunger urged the workpLece against the belt with a load of 13.6 kg, as the belt was driven at about 2050 meters per minute. After one ~inute of elap~ed grlnding time, the workpiece-holder assembly was removed and reweighed, the amount of stock removed calculated by subtracting the abraded weight from khe original weight, and a new, pre-weighed workpiece and holder was mounted on the equipment.
Examples 1 through 3 ~ Examples l through 3 compare coated abrasives `~ having decreasing ratios of aluminum oxide to marble. The aluminum ox~de was heat treated and is not considered to be a premium abrasive grain. The marble, which is the same marble used in the rest of the examples, was purchased under the trade designation Carthaqe Marble from JM Huber Corp. The backing was XW, the grains were blended together, and the size coat was KBFSC with an average weight of 270. The cut data is reported in Table 2; with the total cut being the amount of material removed in 20 minute~ of grin~ing.
'' ~3~6;~
Tab1e 2 Comparison o~ different ratios of a nonpremium abrasive grain to a nonabrasive diluent grain.
Volume Ratio Grain Total Cut ExampleAluminum Oxide/Marble Wei~ht (grams) ... . . _ .
2 50/50 5~0 639 It can be seen from the above data that as the amount of nonabrasive diluent grain was increa~ed from 25 lS volume percent to 75, and the amount of the nonpremium abrasive grain decreased, the performance decreased.
Examples 4 and 5 Examples 4 and 5 compare the abrasive performance of a coated a~rasive containing 100~ aluminum oxide abrasive grain to one containing a blend oP aluminum oxide abrasive grains with marble diluent grains. The aluminum oxide was fused brown aluminum oxide and is not considered to be a premium abrasive grain. The backing was YW, the grains were blended toqether and the size coat was KBFSC.
The make coat weight was 245, grain weight was 612 and the si~e coat weight was 294. The cut data corresponding to 20 minutes of ~rinding is reported in Table 3.
;.
Table 3 Comparison of different ratios of a nonpremium abrasive grain to a nonabrasive diluent grain.
Volume Ratio Cut Example Aluminum Oxide/Marbl_ (grams) 4 lQ0/~ 854 75/25 ~55 ~2~31~2 These examples demonstrate essentially the same performance, despite the removal o~ 25~ of the abrasi~e grain and its replacement with the nonabrasive marble diluent.
Examples 6_throu~7h_9 Examples 6 through 9 compare coated abrasives o~
the invention having decreasing ratios of ceramic based aluminum oxide containing yttrium oxide premi~m abrasive grain to a marble nonabrasive diluent grain. The premium abrasive grain was made according to European patent application EP 228,856, published July 15, 1987. The backing was XN, the grains were blended together and the ~iæe coat was KBFSC. The grinding was terminated when the 15 flnal cut was approximately less than 60 grams per minute.
The coating weights and test data are reporte~ in Tables 4 and 5, respectively.
Table 4 : ~0 Coating Weights Make Grain Size 6 226 ~24 297 : 7 24~ 561 3û6 8 . 243 566 28i ~ :, Table 5 Comparison of different ratios of a premium ~: 30abrasive grain to a nonabrasive diluent grainO
Volume Ratio Cut ~ Example Premium~Grains/Diluent Grains (grams) : 6tcontrol) 100/0 1295 7 75/25 1~42 .. 8 50/50 1542 9 25/75 162g ~, `:
3 ~ 6 It can be seen ~rom the above data that the abrasive performance increased as the amount of pre~ium abrasive grains replaced by nonabrasive diluent grains increased.
: 5 Examples_10 throu~h 15 .
Examples 10 through 15 compare coated abrasives having decreasing ratios of fused alumina-zirconia premium ~ abrasive grain to gypsum nonabrasive diluent grain. The i 1~ gypsum wa6 industrial gypsum purchased from US Gyp~um and is the same gypsum used in the remainder of the examples.
The backing was YS, the grains were blended togeth~er, and the ~ize coat was CRSC. The make coat weight was 335 and the size coat weight was 286. Grinding wa~ terminated when : 15 the final cut was less than 35 grams in sixty seconds. The cut data is reported in Table 6.
: Table 6 : Comparison between different ratios of : 20 alumina zirconia and gypsum.
. Volume Ratio Grain Total Cut Alumina-Zirconia/Gypsum Welght ~
10 . lO0/0 712 4g5 25 11 :80/20 63~ 6~8 12 60/40 60~ 756 I4 20/80 4~0 1034 In this set of examples the optimum nonabrasive~
: diluent loading is approximatel~ 80% by volume. It is surprising and unexpected that a coated abrasive having only 20~ premium abrasive grain cut over twice as much as a ~ ~35 coated abrasive having 100% premium abrasive gr~in.
``:
~L~9;~362 Examples 16 and 17 Examples 16 and 17 compare the abra~ive per~ormance of grade 50 coated abrasives containing a blend of premium abrasive grains and nonabrasive diluent grains, the abrasive and diluent grains being mixed together and applied as a single layer in one, versus the grains being applied as separate layers in the other. The volume ratio of the fused alumina-zirconia premium abrasive grain to the marble nonabrasive diluent grain was 60:40. The backing w~s YW, the size coat was CRSC and a supersize coat was applied. The grinding test was terminated when the final cut was less than 40 grams in slxty seconds. The coating weights and grinding data are reported in Table 7.
Table 7 Grains ~lended vs. Grains in Separate Layers.
Coating Weights Total Cut 20 Ex~mpleMake Grain Size Supersize (~r~ms) 16 blend 210 557 356 13~ 2330 17 layer~ 281 637 289 159 2617 A performance increase of 12% is shown when the premium abrasive grains and nonabrasive diluent grains are applied in ~eparate layers rather than being blended together and applied as a single layer.
ExamE~s 18 and 19 T~e6e examples compare the coated abrasive performance using marble, versus gypsum, as the nonabrasive diluent in combination with fused alumina-zirconia as the premium abrasive grain. Examples 18 and 19 were fabricated and tested in the same manner as Example 17. Example 18 conta~ned marble as the nonabrasive diluent ~rain and , ~
~LZ~3~36~
.
Example 19 contained gypsum as the nonabrasive diluent : grain. The coating weights and cut results are reported in Table 8.
Table 8 ; Comparison of Marble vs. Gyp6um 10as the Nonabra~ive Diluent Grain Coating Weiyhts Total Cut ExampleMake Grain Size Supersize (grams) 1~ marble210 557 356 123 2330 15lg 9ypsum ld9 507 306 96 2605 A performance increase of 12% is shown when gypsum i8 the nonabrasive diluent grain rather than marb1e.
Examples 20 through 25 : Examples 20 through 25 co~pare the abrasive performance of coated abrasives made using a blend of fuæed alumina-zirconia as the premium abrasive grains with : several diluent:grains of various hardnesses. The backing was YW and the size coat was CCSC. The blend of grains comprised 80% by volume diluent grains and 20% by volume fused alumina-zirconia. The coating weights, nonabrasive diluent~, and the cut data are reported in Table 9. The ~ri~ding test was terminated when the stock removed in 60 ~econds was less than 30 gra~s. A control having no ~ diluent grains is provided ~or comparison.
,:~
:. 35 ' ~2~93~
: Tabl e 9 Comparison of Different Diluents.
Coating Weights Total Cut 5Example Diluent Make Grain Size (~rams) Control 201 708 335 665 21 Gypsum 205 532 285 671 22 Pumice 201 708 218 279 23 Garnet 189 440 253 463 24 Emeey 195 520 226 478 - 25 ~rown 205 532 243 452 Al203 It can be Seen f rom this data that gypsur~ was the be8t diluent grain tested, .' ~
', :
;~ 20 , :
:
~.~ 25 ~: : :
:
: , 3 0 '' ~ 35 :
:'~
. ,
Claims (21)
1. A coated abrasive article comprising a backing member having adherently bonded thereto by a bonding material a volume of particles as a layer, said particles consisting essentially of a blend of premium abrasive grains and nonabrasive inorganic diluent grains having a Knoop hardness less than 200.
2. A coated abrasive article comprising a backing member having adherently bonded thereto by a bonding material a volume of particles as a layer, said particles consisting essentially of a blend of premium abrasive grains and nonabrasive inorganic diluent grains having a Knoop hardness less than 200, said coated abrasive article having at least the same abrasive performance as the same abrasive article with all of said volume consisting of particles of said premium abrasive grains.
3. A coated abrasive article as in claim 1 wherein said backing member is selected from the group consisting of paper, polymeric film, cloth, vulcanized fiber, nonwoven web, and combinations thereof.
4. A coated abrasive article as in claim 1 wherein said bonding material is selected from the group consisting of hide glue, phenolic resin, epoxy resin, acrylate resin, melamine resin, urethane resin, urea-formaldehyde resin and combinations thereof.
5. A coated abrasive article as in claim 1 wherein said premium abrasive grain is selected from the group consisting of alpha alumina-based ceramic materials, used alumina-zirconia, refractory coated silicon carbide, diamond, cubic boron nitride, and combinations thereof.
6. A coated abrasive article as in claim 1 wherein said diluent grain is comprised of marble.
7. A coated abrasive article as in claim 1 wherein said diluent grain is comprised of gypsum.
8. A coated abrasive article as in claim 1 wherein said nonabrasive diluent grains comprise 10 to 95 percent of said volume of said particles.
9. A coated abrasive article as in claim 1 wherein said nonabrasive diluent grains comprise 50 to 80 percent of said volume of said particles.
10. A coated abrasive article as in claim 1 wherein said bonding material comprises a make coating of adhesive on one major surface of said backing member and an adhesive size coating overlying said make coating and said particle layer.
11. A coated abrasive article as in claim 10 wherein said size coating contains a grinding aid.
12. A coated abrasive article as in claim 10 wherein said size coating contains a grinding aid selected from the group consisting of potassium fluoroborate, cryolite, sodium chloride, sulfur, potassium titanium fluoride, polyvinyl chloride, polyvinylidene chloride, and mixtures thereof.
13. A coated abrasive article as in claim 10 wherein said bonding material further comprises an adhesive supersize coating overlying said size coating.
14. A coated abrasive article as in claim 13 wherein said supersize coating contains a grinding aid.
15. A coated abrasive article as in claim 13 wherein said supersize coating contains a grinding aid selected from the group consisting of potassium fluoroborate, cryolite, sodium chloride, sulfur, potassium titanium fluoride, polyvinyl chloride, polyvinylidene chloride, and mixtures thereof.
16. A coated abrasive article comprising:
(a) a polyester cloth backing material;
(b) a make coating of calcium carbonate-filled resole phenolic resin on one major surface of said backing material;
(c) a layer of particles of essentially the same grade comprising a blend of 20 to 50% by volume fused alumina-zirconia premium abrasive grains and 80 to 50% by volume gypsum nonabrasive diluent grains adhered to said backing material by said make coating;
(d) a size coating of resole phenolic resin containing cryolite grinding aid overlying said layer of particles; and (e) a supersize coating of epoxy resin containing potassium fluoroborate grinding aid overlying said size coating.
(a) a polyester cloth backing material;
(b) a make coating of calcium carbonate-filled resole phenolic resin on one major surface of said backing material;
(c) a layer of particles of essentially the same grade comprising a blend of 20 to 50% by volume fused alumina-zirconia premium abrasive grains and 80 to 50% by volume gypsum nonabrasive diluent grains adhered to said backing material by said make coating;
(d) a size coating of resole phenolic resin containing cryolite grinding aid overlying said layer of particles; and (e) a supersize coating of epoxy resin containing potassium fluoroborate grinding aid overlying said size coating.
17. A coated abrasive article comprising:
(a) a polyester cloth backing material;
(b) a make coating of calcium carbonate-filled resole phenolic resin on one major surface of said hacking material;
(c) a layer of particles of essentially the same grade comprising a blend of 20 to 50% by volume alpha alumina-based premium abrasive grains and 80 to 50% by volume gypsum nonabrasive diluent grains adhered to said backing material, by said make coating;
(d) a size coating of resole phenolic resin containing cryolite grinding aid overlying said layer of particles; and (e) a supersize coating of epoxy resin containing potassium fluoroborate grinding aid overlying said size coating.
(a) a polyester cloth backing material;
(b) a make coating of calcium carbonate-filled resole phenolic resin on one major surface of said hacking material;
(c) a layer of particles of essentially the same grade comprising a blend of 20 to 50% by volume alpha alumina-based premium abrasive grains and 80 to 50% by volume gypsum nonabrasive diluent grains adhered to said backing material, by said make coating;
(d) a size coating of resole phenolic resin containing cryolite grinding aid overlying said layer of particles; and (e) a supersize coating of epoxy resin containing potassium fluoroborate grinding aid overlying said size coating.
18. A coated abrasive article as in claim 1 wherein said premium abrasive grains and said nonabrasive diluent grains are of the same grade.
19. A method of making a coated abrasive article comprising the steps of:
(a) coating one major surface of a backing material with a layer of uncured adhesive;
(b) applying a layer of particles over said layer of uncured adhesive, said particle layer comprising a blend of premium abrasive grains and nonabrasive inorganic diluent grains having a Knoop hardness less than 200;
(c) partially curing said layer of uncured adhesive;
(d) applying a layer of uncured adhesive over said layer of particles; and (e) completely curing said layers of adhesive.
(a) coating one major surface of a backing material with a layer of uncured adhesive;
(b) applying a layer of particles over said layer of uncured adhesive, said particle layer comprising a blend of premium abrasive grains and nonabrasive inorganic diluent grains having a Knoop hardness less than 200;
(c) partially curing said layer of uncured adhesive;
(d) applying a layer of uncured adhesive over said layer of particles; and (e) completely curing said layers of adhesive.
20. A method as in claim 19 wherein said layer of particles is applied by electrostatically coating an admixture of the premium abrasive grains and the nonabrasive diluent grains.
21. A method as in claim 19 wherein said layer of particles is applied by first drop coating the nonabrasive diluent grains followed by electrostatically coating the premium abrasive grains.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21679988A | 1988-07-08 | 1988-07-08 | |
| US216,799 | 1988-07-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1293862C true CA1293862C (en) | 1992-01-07 |
Family
ID=22808560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000603558A Expired - Lifetime CA1293862C (en) | 1988-07-08 | 1989-06-22 | Coated abrasive products employing nonabrasive diluent grains |
Country Status (2)
| Country | Link |
|---|---|
| KR (1) | KR930007104B1 (en) |
| CA (1) | CA1293862C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US12053857B2 (en) | 2016-12-23 | 2024-08-06 | Saint-Gobain Abrasives, Inc. | Coated abrasives having a performance enhancing composition |
-
1989
- 1989-06-22 CA CA000603558A patent/CA1293862C/en not_active Expired - Lifetime
- 1989-07-08 KR KR1019890009815A patent/KR930007104B1/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US12053857B2 (en) | 2016-12-23 | 2024-08-06 | Saint-Gobain Abrasives, Inc. | Coated abrasives having a performance enhancing composition |
Also Published As
| Publication number | Publication date |
|---|---|
| KR900001462A (en) | 1990-02-27 |
| KR930007104B1 (en) | 1993-07-30 |
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