CA2195546A1 - Abrasive article - Google Patents

Abstract

An abrasive article comprising a substrate having a first major surface and an adhesive layer having abrasive particles embedded therein coated on the first major surface of the substrate, the adhesive layer comprising a hot melt adhesive comprising a polymer cross-linked via hydrolyzed or condensed silyl groups; and a method of preparing an abrasive article, the method comprising (a) providing a substrate having a first major surface, (b) applying an adhesive layer comprising a moisture-curable hot melt adhesive comprising a polymer having hydrolysable or condensable silyl groups to the first major surface of the substrate, the hot-melt adhesive being in a molten or semimolten state, (c) depositing abrasive particles on the adhesive layer, and (d) curing the hot-melt adhesive.

Description

~O 96~05022 2 1 9 ~ 5 ~ ~ P~ ' 16 I ~ ' ABRASIVE ARTICLE

Field of the Invention This invention relates to an abrasive article uu" ,,u(i~i, ,9 a cured hot melt adhesive and to a method of p, ~Udl dliUn.

Backaround of the Invention Abrasive products are normally prepared by coating one surface of a substrate with a first binder layer having adhesive properties, often referred to in the art as the "make". Particles of abrasive material are 5 applied to the coated substrate and partially e",bedded therein. A layer of a second binder, often referred to as the "size~, is then applied to the material. The thickness of the second binder layer regulates the amount of the abrasive material extending above the binder medium. Anti-loading or anti-static materials having generally been included in a further optional 20 layer, referred to in the art as the asupersize~.
The adhesives used to form the make are generally water- or solvent-based and include phenolic resins, urea-ru,lllaldehyde~ melamine-ro""aldel ,yde and co" ~bi~ ,c,liu, ,~ thereof. Other adhesive which have been used are based on animal hide glue and starch. Similar adhesives have 25 been used for the size.
Many of the known adhesive systems which have been used are of low solids content requiring a high energy input for drying and the careful selection of backing materials. In the case of solvent-based adhesives, apparatus to extract solvent emissions may also be needed. Such 30 extraction apparatus may also extract the fines from the abrasive particles Ieading to p~u~es~ g problems.

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W096/05022 ~195~541,~;,1 j, P.~ ,3~ 6 --British Patent No. GB 2,282,144, discloses an abrasive eiement CUIII,IJI i~ g a substrate bearing layer of a moisture-cured hot melt polyurethane adhesive having abrasive particles ~",bedded therein.
It has been found that the use of a moisture-cured hot melt 5 poiyurethane adhesive as the make in an abrasive element provides a number of advantages over traditional water- and solvent-based systems.
The hot melt adhesive is used at 100% solids content and by suitable selection of the a,), ' " , temperature will maintain the desired U~i~l lldLioo of the abrasive particles The hot melt adhesive is co"",dtible 10 with many size formulations and allows thè ,, I " , of water-based size over the make and abrasive particles, the moisture content of the size pdl Li-,i,Udlil ~g in the curing of the make adhesive ensuring strong bonding between the make and the size; Other sizes may be employed, e.g., hot melt or solvent-based formulations, and may be applied before or after 5 curing the make adhesive coating.
Hot meit adhesives are 100% solid polymeric materials which form bonds on cooling. They are generally composed of a ~" "L,i, IdliOn of resins, waxes and stabilizers. Coating is normally by die coating or extrusion, but can also be by spray coating. Moisture-cured polyurethane 20 coatings comprise isocyanate-ltl""i" ' ' In~poly~ which, after a~ dli~JI 1, are cured by reaction of the residual isocyanate groups with moisture. The amino groups initially formed react with more isocyanate groups to fonm urea linkages.
The moisture curing hot melt polyu;ethane (HMPU) may be applied 25 to any substrate which will withstand the l~,, I " I l~" ,pe, ' ~re of the adhesive. The HMPU may be coated directly on the substrate or a priming or presize layer may be applied prior to its 1, pl " ,. These priming or presize layers rnay be solvent-based, water-based or hot melt. The priming or presize layer is conveniently hot melt since it may readily be 30 applied at the same coating station as the HMPU make. Priming or presize layers are particularb useful on substrates which have rough ~ .
--2-- .

~VO96105022 2~9~i4~ r~ 16 surfaces or surfaces with voids e.g., open-cell foams, and woven and non-woven fabrics, since it assists in s,, loull ,i"g the surface and reduces the amount of HMPU required for the make, which tends to be a more expensive ~Il I~Jont:l ll than the presize material. Priming or presize layers are not normally required on closed-cell foams and other substrates having a sub~ld, lli.,l'y sealed surFace.
Moisture-curing hol melt adhesives in which the cure involves il IN,. d~liUI I~ of silyl groups are known in the literature, and some are available co"""e",; .'j. Such materials can be totally free of isocyanates, lo as described in GB 2237022, WO 92/05226, GB 2197326, EP 0202491, US 4,960,844 and Japanese Published Appiication Nos. 4-202585, ~114078. and 3-149277. Moisture-curing hot melts culllclillil~9 both isocyanate and silyl groups have also been disclosed.

Summarv of the Invention The present invention utilizes alternative hot melt adhesives not requiring the use of isocyanates in the ,ult:,udldlioll of abrasive elements.
One aspect of the present invention relates to an abrasive article cc " ,,u, isi"u a substrate co" ,u, isi"g a first major surface, an adhesive layer ~ 20 on said first major surface of said substrate; said adhesive layer cu, "~,, isi"g a hot melt adhesive c.u" l~n i:,i"g a polymer cross-linked via hydrolyzed or cùndt,nsed silyl groups and abrasive particles adhered therein.

2~ Detailed DescriPtion of the Invention The adhesive used in the present invention is a 100% solids resinous formulation which melts to a fluid state at elevated temperatures r (e.g., in the range 50 to 200~C). At the fluid state, the adhesive may be coated on a substrate by conventional techniques such as extrusion, die ~, 30 coating, spraying etc. On cooling to ambient lellll,~l Ires, the adhesive solidifies and further cures to a cross-linked three-di",t:nsiù"al network via W0 96/05022 ~ r~ 16 the mutual iut~.d~Liul) of silyl groups illculpuldlt:d in the resin, the curing reaction being activated by moisture.
Abrasive articles of the invention may be manufactured by coating a surface of a suitable substrate with the hot melt adhesive as described above, and applying abrasive particles to the molten or semi-molten adhesive coating so that they become adhered therein. The:,; I ' ~ of abrasive particles may be, for example, by drop coating or eleuL,u:.ldli~a:'y coating the particles, both of which are standard techniques in the abrasives industry. The thickness of the adhesive coating and the o di~ iul l~ of the particles are preferably such that most if not all of the particles partially project above the surface of the coating. As the adhesive cools, it solidifies completely and cures to a three-,li" ,ensic, Idl network, and hence bonds the particles firmly to the substrate.
The substrate may comprise any of the materials commonly used as the backing for coated abrasive articles, inc!uding paper, cloth, plastic films, plastic fibers, fibrous bases, woven and nonwoven webs/fabrics, foams, foamed polymeric materials, and laminates etc. The substrate, as described above, optionaliy may be precoated with a suitable resin (=pre-sized") in order to seal the surface, for example, or otherwise modify its surface properties. A pre-size may be beneficial in the case of porous materials and/or irregular surfaces, as in open cell foams, nonwoven webs etc.
Suitable presizes may be applied as solvent- or water-based formulations, or as 1 ûû~/ solids hot melt formulations. Hot melt formulations are preferred and examples include a hot me!t ethylene vinyl acetate uu" " "~" -"y available from Evode, Stafford, stdrrul d~hil ~l United Kingdom, under thè trade cle~ J, IdLiun ~Thel " '' ~w 6876~; a hot melt polyethylene co"""~,uia"y available from r~ "~esotd Mining and t Manufacturing Company, St. Paul, MN, under the trade deai~, Idliul ~
30 "3748"; a hot melt polyamide cc " " ~ ~1 ui~lly available from Mi. "~esuta Mining and Manufacturing Company, St. Paul, MN, under the trade 21g~4~
~0 96/05022 = P._llu~ _~J16 desi~, Idliun "3789~. In some circumstances, a pre-formed plastic fllm may be applied to the substrate, which is a useful option where the substrate is an open cell foam, or a woven or non-woven fabric.
The abrasive article may ad.liliu, ,a"y comprise a size layer. The 5 size layer may comprise any of the materials conventionally used, but preferably comprises a II,t"",ost,lli"g resin (e.g., phenol-ru,,,,aldel,yde or urea-rul " Id~ l ,yde) in the form of an aqueous solution or .li;,~ iu, "
coated and cured according to conventlonal techniques. The water from such a coating serves to activate the curing reaction in the adhesive layer, 10 while the ll ,t:""us~lli"g resin provides additional strength and controls the degree to which the abrasive particles project above the surface. Suitable size materials include a water-based acrylic co"" "e, ~ 'ly available from Evode, Stafford, Stdrru, d:,hi, t7, United Kingdom, under the trade d~;ylldliulMDP-90-41û1"; water-based polyurethanes co"""e" 'Iy 5 available from Baxenden, Droitwich, Wulu~ , United Kingdom, under the trade dea;.~,ldiiun "Wituobond 732', 'Wit~,ubol1d 769" and "W;t~.ubond 788". Other sizes may be employed, e.g., hot melt or solvent-based formulatlons, which may be applied before or after curing the make adhesive coating. Additives such as anti-loading 1,~dll,,c~ , static control 20 agents, etc., may be included in the size layer, or coated in a separate (supersize) layer, in acuc, ddl)(~r3 with known techniques.
The abrasive articles may also comprise a supersize, preferably dllliluddillg supersize of the type disclosed in U.S. Patent No. 5,164,265 and its equivalent, EP-0433031. Particularly preferred supersize 25 ~",,uc,silions comprise calcium stearate and a fluorinated additive, e.g., a fluorinated additive cu, "" ,t:, uially available from Mi. "~esold Mining and Manufacturing Company, St. Paul, MN, under the trade de~ l Idliul~
'FC396n, in a water-based acrylic binder, e.g., a water-based acrylic binder co"""e" 'ly available from Vinamul, Carshalton, Surrey, United Kingdom, 30 under the trade desiy, Idliul MVinacryl'.

; f ~
WO 96105022 ~ , 16 The hot melt adhesives useful in the invention comprise a uoss-linkable polymer having silyl groups, ~,u, t:se, lled by the formula:
-A-Si(R)~m(X)m in which:
A I ~ul t~ l Ib a divalent organic radical, preferably an optionally hstitl lt~d alkylene, alkyleneoxy, alkylene-phenylene, or alkylene-oxy-alkylene chain;
X ,~u, ~:.e, It~ a leaving group ~ .Q,II ~le by hydrolysis, preferably a halogen atom, e.g., chlorine, or a group R'O or R1COO in which R~ is a C,.,0, preferably C1~, alkyl or alkoxyalkyl group;
m is 1, 2, or 3, preferably 2 or 3; and R I tlu~:se~ . a blocking group not ~ ..re..hl~ by hydrolysis, for example, a C14 alkyl group, a cycloalkyl of up to 8 carbon atoms, or an aryl group oF up to 10 carbon atoms.
Such silyl groups are readily hydrolyzed by moisture (from the ~6~w:~,ul~ or extemally supplied) to from silanol groups Si - OH, which condense with one another to form -Si-O-Si- linkages as disclosed, for example, in WO 92/05226, co"~,uulldil,g to U.S. Patent Nos. 5,227,442;
5,296,561; and 5,397,648.
The silyl groups are covalently bonded to one or more of the resin(s) constituting the hot melt adhesive. This may be achieved by grafting reactions carried out on a preformed polymer, or by cu,uûly",eli~dli,)ll with suitable silane-functional l"opu",e~. Both d,U~ ~uaulles are fully documented in the literature, for example, GB 2237022 and WO 92/05226 (~,o"~ .u"di"g to U.S. Patent Nos.
5,227,442; 5,296,561; and 5,397,648). In the resulting polymers, silyl groups are attached to about 0.1 to 20.0 rnol~/O of the repeating units, more commonly about 0.3 to 5.0 mol~h. The remaining repeating units may be derived from any of variety of " ,u, ,u m ~ 1l such as alpha-olefins, acrylates and other vinyl compounds, as described in the prior art.
.

0 96/05022 ~ ~ 9 ~ r~ ,J-6 The hot melt adhesive may comprise additional resins, especially tackifying resins, in order to adjust the physical properties such as melt viscosity. The adhesive may also comprise a catalyst for the curing reaction, the preferred catalyst being an organotin compound or a titanate, 5 such as dibutyltindilaurate or tetrabutyltitanate. Typical catalyst loadings - are in the range 0.1 to 2.5% by weight based on the weight of total solids.
In e"lLodi",t" ,1;, of the invention cu,,,,uri~ ,9 an aqueous size coating, a catalyst may be u""ecessdl y. Hot melt adhesives co, lldil ,i"g a cure catalyst optionally may be used in two-part form, with the catalyst and silane-functional resin supplied separately and mixed i"""edidLely priorto coating or during the coating process e.g., by extrusion through adjacent dies.
A ,,u"""e,~,ia"y available hot melt adhesive suitable for use in the invention was supplied by Swift Adhesives Ltd., Twick~l Ihdl ", United Kingdom, under the trade dt~ , Idliul ~ ~X200/9n. One method for preparing this adhesive is believed to be as follows: combining a silane grafted copolymer in an amount of about 15 parts by weight; a hydl u~ndIud alicylic hy.ll UCdl L,on-solid midblock cu",,udLil,le tackifying resin availablefrom Exxon Chemical Company, Houston, TX, under the trade desiy, IdIion ~Escorez 5380= in an amount of about 40 parts by weight; polybutene -liquid mid-block uo,,,~,dlil,le plasticizer available from BP Chemicals, Cleveland, OH, under the trade desiy, IdIion "Hyvis 30= in an amount of about45partsbyweight;acatalyst",d~ ,bdtil,(1~/Obyweightdibutyltin dilaurate in ethylene vinyl acetate) in an amount of about 1.7 parts by weight; and an dl lliU~iddrll available from Ciba Geigy, Ardsley, NY, under the trade desiy, IdIion ~Irganox 1010" in an amount of about 1 part by weight.
The silane grafted copolymer (i.e., a silane grafted styrene ABA
block copolymer) can be prepared as follows: 100 parts by weight of a styrene-ethylene-butylene-styrene block copolymer available from Shell Chemical Company, Houston, TX, under the trade desiy, IdIion "Kraton WO 96/05022 2 19 ~ 5 ~ 6 ~ 16 G1652" can be reacted with two parts by weight of vinyl trimethoxy silane using 0.17 parts by weight of dicumyl peroxide as a free radical generator and 0.5 parts by weight of an dl lliU)~iddl 11 available under the trade dtssi~" IdLion "Flectol H," from Monsanto. The reaction can be carried out in 5 a PR46 Buss Ko-Kneader with the heater units set at 200~CI240~C/160~C
and the die heater at setting number 7. The material produced can be face cut and air cooled at an output rate of 5.2 kg per hour.
The co,,,,uosiliun can be ho",og~:"i~t:d prior to the addition of the catalyst. The catalyst can then be mixed in and the UU,l~,UO~iliu" can be o filled into a container for a hot melt adhesive applicator. A silica gel sachet may be placed in the filled container before it is sealed. This ~ pd(dlio is esselllially as described in Example 3 of GB 2237022.
The hot melt adhesive used in a given:,, I ' , will be selected according to the particular requirements. As a general guide, hot melt adhesives having viscosities in the range 3,000 to 12,000 mPa.s (Brookfield) at 120~C are suitable, but those exhibiting higher or lower values may be dUUlUU~idll~ in certain circumstances. For example, a less viscous adhesive will normally be required if a lower coating lt:",,ue, ' Ire isto be used, and a more viscous adhesive may be suitable if a higher 20 coating temperature can be tolerated.
The make coating is generally applied by heating the hot melt adhesive to a temperature at which the viscosity is suitable for coating and applying the molten material to the substrate by an extrusion die, or optionally two adjacent dies in the case of two-part cu" "~osiliu". Coating 25 temperatures depend upon the particular adhesive, but are generally in the range 50 to 200~C, usually in the range 120~ to 160~C. The coating weight depends upon the surface of the substrate, the presence or absence of a presize, and the size of the abrasive particles. Coating weights are generally within the range 1 to 250 g/m2, the lower end of the range being 30 applicable to smooth substrates e.g., paper, and to the use of fine grade abrasive particles.

'2195~
~!/O 96105022 ~ P~ J16 ;, ~ ~ .

Hot melt size and presize coatings may be applied in a similar manner to the make coating.
The abrasive particles are generally applied to the coated substrate i"",.- " ' !y a~tem1p, 1 - " 1 of the adhesive e.g., by passing the substrate through a curtain of abrasive particles or by t:le-,ll ualdli-, coating.
- Preferably the abrasive particles are heated prior to "Pr' " ~ e.g., from 30 to 15û~C usually about 50~C.
Individual abrasive particles may be selected from those commonly used in the abrasive art, however, the abrasive particles (size and culll,uo:,iliul)) can be chosen with the d,uplicdliul ~ of the abrasive article in mind. In choosing an a,u~Jlu~ridl~ abrasive particle, ~,hdld~ ,a such as hardness, cc"" "' "'.y with the intended workpiece, particle size, reactivity with the workpiece, as well as heat conductivity may be co,~si.l_, ~cl.
The co",,uosiliù" of abrasive particles useful in the invention can be ~ divided into two classes: natural abrasives and manufactured abrasives.
Examples of natural abrasives include: diamond, conundum, emery, gamet, buhrstone, chert, quartz, sd"d~lu"e, ~.hdl-,e-lully, flint, quartzite, silica, feldspar, pumice and talc. Examples of manufactured abrasive include: boron carbide, cubic boron nitride, fused alumina, ceramic aluminum Dxide, heat treated aluminum oxide, alumina zirconia, glass, silicon carbide, iron oxides, tantalum carbide, cerium oxide, tin oxide, titanium carbide, synthetic diamond", la~dl ,ese dioxide, zirconium oxide, and silicon nitride.
Abrasive particles useful in the invention typically and preferably have a particle size ranging from about 0.1 ~iu~u~ r to about 1500 ~"iu,u",t~ , more preferably ranging from about 0.1 ~iu~u~eler to about 1300 ",iu,u",~ . The abrasive particles preferably have an average particle size ranging from about 0.1 ~ UIII~,'U. to about 700 ,,,i~,,u,,,t:tt~
more preferably ranging from about 1 to about 150 "~iu~u"~
particularly preferably from about 1 to 80 ",i~,, u, llt:Lt:l ~. It is preferred that WO 96/0~5022 2 1 ~ S~i 6 r ~ ,316 abrasive particles used in the invention have a Moh's hardness of at least 8, more preferably about 9; however, for specific,, I ' ,:,, softer particles may be used.
The temm ~abrasive particle" includes ayu~lu,,,eldlus of individual ,~
abrasive particles. An abrasive ay~lullleldLu is formed when a plurality of abrasive particles are bonded together with a binder to form a larger abrasive particle which may have a specific particulate structure. The plurality of particles which form the abrasive agylu,,,u, ' may comprise more than on type of abrasive particle, and the binder used may be the o same as or different from the binders used to bind the agulu,,,e, dLt: to a backing.
A size may be applied directly after: ?.P " ~ of the abrasive particles. The size is préferably water-based and may readily be applied by, e.g., spray-coating or roller-coating. The weight ratio of adhesive to waterisgenerallywithintherange10:1to1:2,preferablyfrom1:1to2:1.
The coating weight is generally in the range from 1 to 250 g/m2 solids and is normally deuu, ,du"l on the grade of abrasive particles.
In absence of water-based size, the material may be sprayed with water or placed in a moist environment to cure the adhesive.
After a,, 1;- ' , of size or water, the material is dried, e.g., by force drying in a tunnel oven with infrared heaters. Suitable drying ~e",,ut:, ~res are about 6ûDC and drying times of about 90 seconds are usually sufficient.
Following drying, the abrasive article is preferably allowed to stand for a period of at least 24 hours to allow thorough curing.
A particularly prefenred product in dUl,UI dance with the invention is an abrasive sponge, e.g., a foam strip of thickness in the range 2 to 15 mm ~ having abrasive particles coated on one major surface. The substrate coated with abrasive particles can be in sheet form or as a web from a roll.
The sponge may be formed in situ in the apparatus upstream of the , .

5 ~
~0 96105022 r~ 16 coating station. Foam blocks, e.g., of a thickness about 25 mm may also be coated with abrasive particles in dCCu~ danu~ with the present invention.
The present invention is not limited to coating a single surface and articles havin~ double sided abrasive coatings, which may be of different abrasive grades, may readily be prepared. Abrasive coating on some or all sides of a substrate is also possible.
The invention will now be illustrated by the following Examples.

ExamDle 1 o A hot melt adhesive co"""e" idlly available from Swift Adhesives Ltd., Twickenham, United Kingdom, under the trade deaiy, IdliUI I "X2ûû/9~
was slot coated at about 14û~C onto paper at coating weights of 22, 32, and 48 grams per square meter, respectively.
Silicon carbide mineral (about 9û grams per square meter), cullllllel.,idlly available from Arendal, Eydehavn, Norway, having the trade deaiyl Idliol, ~P22û' was drop coated on to the tacky, uncured coating at ambient le",~e, ' ~re.
One sample of paper was drop coated after re-heating the adhesive to 1 6û~C for 60 seconds.
All samples showed sufficient adhesion of mineral to further coat with size.
A water-based ures/Fu""ald~hyde size mix COllllllt:l uia 'y available from Dynochem, Duxford, Cdlllblidgeallil~:, United Kingdom, underthe trade desiy"dliùn "CBUL" was coated onto the samples described above.
Drying/curing was effected for two hours at 80~C.
The abrasive grains in the abrasive layer of the resulting product(s) felt sharp. A brief cut test was performed as follows: A sample of the coated abrasive article was converted into a 5.û cm x 15 cm rectangular sheet and weighed. A dry bnush and a sheet of paper were also weighed.
The paper was larger than a wooden panel which was precoated with a water based acrylic lacquer CGIlllll~:l 'ly available from Granyte Surface . -, t~

96/05022 1~ 6 Coatings PLC, Salford, England. The rectangular coated abrasive article was wrapped around a 5 cm x 2.5 cm rubber block having about a 60 degree l"l_" IdIiul ,al Rubber Hardness. In a manual, hand-held, operation, the abrasive article on the rubber block was moved in push-pull strokes 5 against the wooden panel sanding the acrylic lacquer. A stroke was the movement of the operator's hand in a straight line back and forth motion covering about 25 cm ~ 5 cm in each motion. After 60 strokes, the brush was used to transfer any dust on the wooden panel to the paper. The weight of acrylic lacquer removed was tlult" " ,i"ed by, u ..e;~l ,i"g the o coated abrasive, brush, and paper. In this manual test, 0.2 grams of acrylic lacquer was removed in 60 strokes which dt:" ,u, lall dIes the abrasiveness of a coated abrasive article in accol ddl ,ce with the present invention.

F)t~rnple 2 A polyester film was slot coated with a hot melt adhesive uc."""~,.,i~.''y available from Swift Adhesives Ltd., Tv.;_ke"l,a"" United Kingdom, under the trade .lesiy, IdIiull, "X200/9~ at about 140DC using a coating weight of 40 grams per square meter.
Silicon carbide mineral collllllel.. ially available Arendal, Eydehavn, Norway, having the trade clesi~, IdIio n UP220" was drop coated onto the tacky, uncured coating at a mineral weight of 185 grams per square meter.
A water-based phenol-ru, " ,aldel ,yde resin was coated over as a size.
Cure was effected at 11 5~C for five hours, and the product was evaluated 25 as described in Example 1 with similar results.

Claims (43)

CLAIMS:

1. An abrasive article comprising a substrate having a first major surface and an adhesive layer having abrasive particles embedded therein coated on said first major surface of said substrate, the adhesive layer comprising a hot melt adhesive comprising a polymer cross-linked via hydrolyzed or condensed silyl groups.

2. The abrasive article as claimed in claim 1 wherein said silyl groups are represented by:
-A-Si(R)3-m(X)m in which:
A represents a divalent organic radical, X represents a leaving group displaceable by hydrolysis, m is 1, 2, or 3, and R represents a blocking group not displaceable by hydrolysis.

3. The abrasive article as claimed in claim 2 in which A is a moiety selected from the group consisting of alkylene, alkylene-oxy, alkylene-phenylene and alkylene-oxy-alkylene, said moiety may be substituted or unsubstituted.

4. The abrasive article as claimed in claim 2 in which X is halogen, R1O- or R1COO-, wherein R1 is a C1-10 alkyl or alkoxyakyl.

5. The abrasive article as claimed in claim 2 wherein R is an alkyl, cycloalkyl, or aryl group.

6. The abrasive article as claimed in claim 2 wherein m is 2 or 3.

7. The abrasive article as claimed in claim 2 wherein said polymer comprises repeating units and said silyl groups are attached to from 0.1 to 20.0 mol% of said repeating units.

8. The abrasive article as claimed in claim 7 wherein repeating units other than said repeating units having silyl group attached are selected from alpha-olefins, acrylates and other vinyl compounds.

9. The abrasive article as claimed in claim 1 wherein the hot melt adhesive additionally comprises a catalyst.

10. The abrasive article as claimed in claim 9 wherein the catalyst is an organotin compound or a titanate.

11. The abrasive article as claimed in claim 10 wherein the catalyst is dibutyltinlaurate or tetrabutyltitanate.

12. The abrasive article as claimed in claim 1 wherein said abrasive layer is overcoated with a size layer.

13. The abrasive article as claimed in claim 12 wherein the size layer is a water-based coating.

14. The abrasive article as claimed in claim 12 wherein the size layer comprises acrylic, polyurethane, phenol, melamine or urea formaldehyde adhesive, a water based epoxy adhesive, or combinations thereof.

15. The abrasive article as claimed in claim 12 wherein the size layer comprises an acrylic binder and calcium searate.

16. The abrasive article as claimed in claim 12 wherein the size has a coating weight in the range of 1 to 250 g/m2 solids.

17. The abrasive article as claimed in claim 12 further comprising a supersize.

18. The abrasive article as claimed in claim 17 wherein the supersize comprises a binder and calcium stearate.

19. The abrasive article as claimed in claim 1 further comprising a presize layer between the substrate and the hot melt adhesive.

20. The abrasive article as claimed in Claim 19 wherein the presize layer comprises a hot melt adhesive.

21. The abrasive article as claimed in claim 19 wherein the presize layer comprises ethylene vinyl acetate, polyethylene or polyamide.

22. The abrasive article as claimed in claim 1 wherein the hot melt adhesive has a coating weight in the range of 1 to 250 g/m2.

23. The abrasive article as claimed in claim 1 wherein the substrate is selected from paper, plastic fibers, fibrous bases, woven and non-woven fabrics, foams, and laminates thereof.

24. The abrasive article as claimed in claim 23 wherein the substrate is a sponge sheet having a thickness in the range of 2 to 15 mm.

25. A method of preparing an abrasive article, the method comprising (a) providing a substrate having a first major surface, (b) applying an adhesive layer comprising a moisture-curable hot melt adhesive comprising a polymer having hydrolysable or condensable silyl groups to said first major surface of said substrate, said hot-melt adhesive being in a molten or semi-molten state, (c) depositing abrasive particles on said adhesive layer, and (d) curing said hot-melt adhesive.

26. The method as claimed in claim 25, wherein said silyl groups are represented by:
-A-Si(R)3-m(X)m in which:
A represents a divalent organic radical, X represents a leaving group displaceable by hydrolysis, m is 1, 2, or 3, and R represents a blocking group not displaceable by hydrolysis.

27. The method as claimed in claim 25 wherein said adhesive is heated to a temperature of from 50 to 250°C prior to application.

28. The method as claimed in claim 27 wherein said adhesive is heated to a temperature of about 140°C.

29. The method as claimed in claim 25 wherein said adhesive is applied having a coating weight in the range of 1 to 250 g/m2.

30. The method as claimed in claim 25 wherein said adhesive is applied as a one part composition.

31. The method as claimed in claim 25 wherein said adhesive is applied in two part form one part comprising a silane functional resin and a second part comprising a catalyst.

32. The method as claimed in claim 31 wherein the silane functional resin and the catalyst are applied by extrusion through adjacent dies.

33. The method as claimed in claim 25 comprising the additional step of applying a size coat after applying the abrasive particles.

34. The method as claimed in claim 33 in which the size coat is water-based.

35. The method as claimed in claim 33 wherein the size coat comprises acrylic polyurethane phenol melamine or urea formaldehyde adhesive a water based epoxy adhesive or combinations thereof.

36. The method as claimed in claim 33 wherein the size coat has a coating weight in the range of 1 to 250 g/m2 solids.

37. The method as claimed in claim 25 comprising applying a presize layer on the substrate prior to application of the hot melt adhesive.

38. The method as claimed in claim 37 wherein the presize layer comprises a hot melt adhesive which is applied in a molten state.

39. The method as claimed in claim 37 wherein the presize layer comprises ethylene vinyl acetate polyethylene or polyamide.
\

40. The method as claimed in claim 25 wherein the substrate is selected from the group consisting of paper, plastics fibres, fibrous bases, woven and non-woven fabrics, foams, and laminates thereof.

41. The method as claimed in claim 40 wherein the substrate is a foam sheet having a thickness of about 5 mm.

42. The method as claimed in claim 25 wherein the abrasive particles are heated to a temperature of from 35 to 250°C prior to depositing.

43. The method as claimed in claim 42 wherein the abrasive particles are heated to a temperature of about 50°C.