Field of the Invention
[0001] This invention relates to an abrasive article comprising a cured hot melt adhesive
and to a method of preparation.
Background of the Invention
[0002] 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 applied to the coated substrate and partially
embedded 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 layer,
referred to in the art as the "supersize".
[0003] The adhesives used to form the make are generally water- or solvent-based and include
phenolic resins, urea-formaldehyde, melamineformaldehyde and combinations thereof.
Other adhesive which have been used are based on animal hide glue and starch. Similar
adhesives have been used for the size.
[0004] 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 extraction apparatus may also extract the fines from the abrasive
particles leading to processing problems.
[0005] British Patent No. GB 2,282,144, discloses an abrasive element comprising a substrate
bearing layer of a moisture-cured hot melt polyurethane adhesive having abrasive particles
embedded therein.
[0006] It has been found that the use of a moisture-cured hot melt polyurethane 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 application temperature will maintain the desired
orientation of the abrasive particles. The hot melt adhesive is compatible with many
size formulations and allows the application of water-based size over the make and
abrasive particles, the moisture content of the size participating 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 curing the make adhesive coating.
[0007] Hot melt adhesives are 100% solid polymeric materials which form bonds on cooling.
They are generally composed of a combination of resins, waxes and stabilizers. Coating
is normally by die coating or extrusion, but can also be by spray coating. Moisture-cured
polyurethane coatings comprise isocyanate-terminated prepolymers which, after application,
are cured by reaction of the residual isocyanate groups with moisture. The amino groups
initially formed react with more isocyanate groups to form urea linkages.
[0008] The moisture curing hot melt polyurethane (HMPU) may be applied to any substrate
which will withstand the application temperature of the adhesive. The HMPU may be
coated directly on the substrate or a priming or presize layer may be applied prior
to its application. These priming or presize layers may be solvent-based, water-based
or hot melt. The priming or presize layer is conveniently hot melt since it may readily
be applied at the same coating station as the HMPU make. Priming or presize layers
are particularly useful on substrates which have rough surfaces or surfaces with voids
e.g., open-cell foams, and woven and non-woven fabrics, since it assists in smoothing
the surface and reduces the amount of HMPU required for the make, which tends to be
a more expensive component than the presize material. Priming or presize layers are
not normally required on closed-cell foams and other substrates having a substantially
sealed surface.
[0009] Moisture-curing hot melt adhesives in which the cure involves interactions of silyl
groups are known in the literature, and some are available commercially. Such materials
can be totally free of isocyanates, as described in GB 2237022, WO 92/05226, GB 2197326,
EP 0202491, US 4,960,844 and Japanese Published Application Nos. 4-202585, 4-114078.
and 3-149277. Moisture-curing hot melts containing both isocyanate and silyl groups
have also been disclosed.
Summary of the Invention
[0010] The present invention utilizes alternative hot melt adhesives not requiring the use
of isocyanates in the preparation of abrasive elements.
[0011] One aspect of the present invention relates to an abrasive article comprising a substrate
comprising a first major surface, an adhesive layer on said first major surface of
said substrate; said adhesive layer comprising a hot melt adhesive comprising a polymer
cross-linked via hydrolyzed or condensed silyl groups and abrasive particles adhered
therein.
Detailed Description of the Invention
[0012] The adhesive used in the present invention is a 100% solids resinous formulation
which melts to a fluid state at elevated temperatures (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 coating, spraying etc. On cooling to ambient temperatures,
the adhesive solidifies and further cures to a cross-linked three-dimensional network
via the mutual interaction of silyl groups incorporated in the resin, the curing reaction
being activated by moisture.
[0013] 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 application of abrasive particles may be, for example, by drop coating
or electrostatically coating the particles, both of which are standard techniques
in the abrasives industry. The thickness of the adhesive coating and the dimensions
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-dimensional network, and hence bonds the particles firmly to
the substrate.
[0014] The substrate may comprise any of the materials commonly used as the backing for
coated abrasive articles, including 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, optionally 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.
[0015] Suitable presizes may be applied as solvent- or water-based formulations, or as 100%
solids hot melt formulations. Hot melt formulations are preferred and examples include
a hot melt ethylene vinyl acetate commercially available from Evode, Stafford, Staffordshire,
United Kingdom, under the trade designation "Thermaflow 6876"; a hot melt polyethylene
commercially available from Minnesota Mining and Manufacturing Company, St. Paul,
MN, under the trade designation "3748"; a hot melt polyamide commercially available
from Minnesota Mining and Manufacturing Company, St. Paul, MN, under the trade designation
"3789". In some circumstances, a pre-formed plastic film 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.
[0016] The abrasive article may additionally comprise a size layer. The size layer may comprise
any of the materials conventionally used, but preferably comprises a thermosetting
resin (e.g., phenol-formaldehyde or urea-formaldehyde) in the form of an aqueous solution
or dispersion, coated and cured according to conventional techniques. The water from
such a coating serves to activate the curing reaction in the adhesive layer, while
the thermosetting 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 commercially available from Evode, Stafford, Staffordshire,
United Kingdom, under the trade designation "DP-90-4101"; water-based polyurethanes
commercially available from Baxenden, Droitwich, Worcestshire, United Kingdom, under
the trade designation "Witcobond 732", "Witcobond 769" and "Witcobond 788". Other
sizes may be employed, e.g., hot melt or solvent-based formulations, which may be
applied before or after curing the make adhesive coating. Additives such as anti-loading
treatments, static control agents, etc., may be included in the size layer, or coated
in a separate (supersize) layer, in accordance with known techniques.
[0017] The abrasive articles may also comprise a supersize, preferably antiloading supersize
of the type disclosed in U.S. Patent No. 5,164,265 and its equivalent, EP-0433031.
Particularly preferred supersize compositions comprise calcium stearate and a fluorinated
additive, e.g., a fluorinated additive commercially available from Minnesota Mining
and Manufacturing Company, St. Paul, MN, under the trade designation "FC396", in a
water-based acrylic binder, e.g., a water-based acrylic binder commercially available
from Vinamul, Carshalton, Surrey, United Kingdom, under the trade designation "Vinacryl".
[0018] The hot melt adhesives useful in the invention comprise a cross-linkable polymer
having silyl groups represented by the formula:
-A-Si(R)
3-m(X)
m
in which:
A represents a divalent organic radical, preferably an optionally substituted alkylene,
alkyleneoxy, alkylene-phenylene, or alkylene-oxyalkylene chain;
X represents a leaving group displaceable by hydrolysis, preferably a halogen atom,
e.g., chlorine, or a group R1O or R1COO in which R1 is a C1-10, preferably C1-4, alkyl or alkoxyalkyl group;
m is 1, 2, or 3, preferably 2 or 3; and
R represents a blocking group not displaceable by hydrolysis, for example, a C1-4 alkyl group, a cycloalkyl of up to 8 carbon atoms, or an aryl group of up to 10 carbon
atoms.
[0019] Such silyl groups are readily hydrolyzed by moisture (from the atmosphere or externally
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, corresponding to U.S.
Patent Nos. 5,227,442; 5,296,561; and 5,397,648.
[0020] 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 copolymerization with suitable silane-functional monomers.
Both approaches are fully documented in the literature, for example, GB 2237022 and
WO 92/05226 (corresponding 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 mol% of
the repeating units, more commonly about 0.3 to 5.0 mol%. The remaining repeating
units may be derived from any of variety of monomers, such as alpha-olefins, acrylates
and other vinyl compounds, as described in the prior art.
[0021] 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, 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 embodiments of the invention comprising an aqueous size coating,
a catalyst may be unnecessary. Hot melt adhesives containing a cure catalyst optionally
may be used in two-part form, with the catalyst and silane-functional resin supplied
separately and mixed immediately prior to coating or during the coating process e.g.,
by extrusion through adjacent dies.
[0022] A commercially available hot melt adhesive suitable for use in the invention was
supplied by Swift Adhesives Ltd., Twickenham, United Kingdom, under the trade designation
"X200/9". 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 hydrogenated
alicylic hydrocarbon-solid midblock compatible tackifying resin available from Exxon
Chemical Company, Houston, TX, under the trade designation "Escorez 5380" in an amount
of about 40 parts by weight; polybutene - liquid mid-block compatible plasticizer
available from BP Chemicals, Cleveland, OH, under the trade designation "Hyvis 30"
in an amount of about 45 parts by weight; a catalyst masterbatch (1% by weight dibutyl
tin dilaurate in ethylene vinyl acetate) in an amount of about 1.7 parts by weight;
and an antioxidant available from Ciba Geigy, Ardsley, NY, under the trade designation
"Irganox 1010" in an amount of about 1 part by weight.
[0023] 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
designation "Kraton 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 antioxidant available under the trade designation "Flectol
H," from Monsanto. The reaction can be carried out in a PR46 Buss Ko-Kneader with
the heater units set at 200°C/240°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.
[0024] The composition can be homogenized prior to the addition of the catalyst. The catalyst
can then be mixed in and the composition can be 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 preparation is essentially as described in Example 3 of
GB 2237022.
[0025] The hot melt adhesive used in a given application 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 appropriate in certain circumstances. For example, a
less viscous adhesive will normally be required if a lower coating temperature is
to be used, and a more viscous adhesive may be suitable if a higher coating temperature
can be tolerated.
[0026] 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 composition. Coating 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/m
2, the lower end of the range being applicable to smooth substrates e.g., paper, and
to the use of fine grade abrasive particles.
[0027] Hot melt size and presize coatings may be applied in a similar manner to the make
coating.
[0028] The abrasive particles are generally applied to the coated substrate immediately
after application of the adhesive e.g., by passing the substrate through a curtain
of abrasive particles or by electrostatic coating. Preferably the abrasive particles
are heated prior to application e.g., from 30 to 150°C usually about 50°C.
[0029] Individual abrasive particles may be selected from those commonly used in the abrasive
art, however, the abrasive particles (size and composition) can be chosen with the
application of the abrasive article in mind. In choosing an appropriate abrasive particle,
characteristics such as hardness, compatibility with the intended workpiece, particle
size, reactivity with the workpiece, as well as heat conductivity may be considered.
[0030] The composition of abrasive particles useful in the invention can be divided into
two classes: natural abrasives and manufactured abrasives. Examples of natural abrasives
include: diamond, corundum, emery, garnet, buhrstone, chert, quartz, sandstone, chalcedony,
flint, quartzite, silica, feldspar, pumice and talc. Examples of manufactured abrasive
include: boron carbide, cubic boron nitride, fused alumina, ceramic aluminum oxide,
heat treated aluminum oxide, alumina zirconia, glass, silicon carbide, iron oxides,
tantalum carbide, cerium oxide, tin oxide, titanium carbide, synthetic diamond, maganese
dioxide, zirconium oxide, and silicon nitride.
[0031] Abrasive particles useful in the invention typically and preferably have a particle
size ranging from about 0.1 micrometer to about 1500 micrometers, more preferably
ranging from about 0.1 micrometer to about 1300 micrometers. The abrasive particles
preferably have an average particle size ranging from about 0.1 micrometer to about
700 micrometers, more preferably ranging from about 1 to about 150 micrometers, particularly
preferably from about 1 to 80 micrometers. It is preferred that abrasive particles
used in the invention have a Moh's hardness of at least 8, more preferably about 9;
however, for specific applications, softer particles may be used.
[0032] The term "abrasive particle" includes agglomerates of individual abrasive particles.
An abrasive agglomerate 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 agglomerate
may comprise more than on type of abrasive particle, and the binder used may be the
same as or different from the binders used to bind the agglomerate to a backing.
[0033] A size may be applied directly after application of the abrasive particles. The size
is preferably water-based and may readily be applied by, e.g., spray-coating or roller-coating.
The weight ratio of adhesive to water is generally within the range 10:1 to 1:2, preferably
from 1:1 to 2:1. The coating weight is generally in the range from 1 to 250 g/m
2 solids and is normally dependent on the grade of abrasive particles.
[0034] In absence of water-based size, the material may be sprayed with water or placed
in a moist environment to cure the adhesive.
[0035] After application of size or water, the material is dried, e.g., by force drying
in a tunnel oven with infrared heaters. Suitable drying temperatures are about 60°C
and drying times of about 90 seconds are usually sufficient.
[0036] Following drying, the abrasive article is preferably allowed to stand for a period
of at least 24 hours to allow thorough curing.
[0037] A particularly preferred product in accordance 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 coating station. Foam blocks, e.g., of a thickness about 25 mm may
also be coated with abrasive particles in accordance with the present invention.
[0038] The present invention is not limited to coating a single surface and articles having
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.
[0039] The invention will now be illustrated by the following Examples.
Example 1
[0040] A hot melt adhesive commercially available from Swift Adhesives Ltd., Twickenham,
United Kingdom, under the trade designation "X200/9" was slot coated at about 140°C
onto paper at coating weights of 22, 32, and 48 grams per square meter, respectively.
[0041] Silicon carbide mineral (about 90 grams per square meter), commercially available
from Arendal, Eydehavn, Norway, having the trade designation "P220" was drop coated
on to the tacky, uncured coating at ambient temperature.
[0042] One sample of paper was drop coated after re-heating the adhesive to 160°C for 60
seconds.
[0043] All samples showed sufficient adhesion of mineral to further coat with size.
[0044] A water-based urea/formaldehyde size mix commercially available from Dynochem, Duxford,
Cambridgeshire, United Kingdom, under the trade designation "CBUL" was coated onto
the samples described above. Drying/curing was effected for two hours at 80°C.
[0045] 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 5.0 cm x 15 cm rectangular sheet and weighed. A dry brush 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 commerically available from Granyte
Surface 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 International
Rubber Hardness. In a manual, hand-held, operation, the abrasive article on the rubber
block was moved in push-pull strokes 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 determined by reweighing the coated abrasive, brush, and
paper. In this manual test, 0.2 grams of acrylic lacquer was removed in 60 strokes
which demonstrates the abrasiveness of a coated abrasive article in accordance with
the present invention.
Example 2
[0046] A polyester film was slot coated with a hot melt adhesive commercially available
from Swift Adhesives Ltd., Twickenham, United Kingdom, under the trade designation,
"X200/9" at about 140°C using a coating weight of 40 grams per square meter.
[0047] Silicon carbide mineral commercially available Arendal, Eydehavn, Norway, having
the trade designation "P220" was drop coated onto the tacky, uncured coating at a
mineral weight of 185 grams per square meter. A water-based phenol-formaldehyde resin
was coated over as a size. Cure was effected at 115°C for five hours, and the product
was evaluated as described in Example 1 with similar results.
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 wherein said polymer comprises repeating
units and said silyl groups are attached to from 0.1 to 20.0 mol% of said repeating
units.
4. The abrasive article as claimed in claim 1 wherein the hot melt adhesive additionally
comprises a catalyst.
5. The abrasive article as claimed in claim 1 wherein said abrasive layer is overcoated
with a size layer.
6. The abrasive article as claimed in claim 5 further comprising a supersize.
7. 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.
8. The method as claimed in claim 7, 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.
9. The method as claimed in claim 7 wherein said adhesive is heated to a temperature
of from 50 to 250°C prior to application.
10. The method as claimed in claim 7 wherein said adhesive is applied in two part form,
one part comprising a silane functional resin and a second part comprising a catalyst.
1. Schleifartikel, umfassend ein Substrat mit einer ersten Hauptoberfläche und eine Klebstoffschicht
mit darin eingebetteten Schleifteilchen, die auf die erste Hauptoberfläche des Substrats
aufgetragen ist, wobei die Klebstoffschicht einen Heißschmelzkleber umfaßt, der ein
Polymer umfaßt, das über hydrolysierte oder kondensierte Silylgruppen vernetzt ist.
2. Schleifartikel gemäß Anspruch 1, worin die Silylgruppen durch
-A-Si(R)
3-m(X)
m
dargestellt werden, worin
A einen zweiwertigen, organischen Rest darstellt;
X eine austretende Gruppe darstellt, die durch Hydrolyse austauschbar ist,
m 1, 2 oder 3 ist, und
R eine Blocking-Gruppe darstellt, die nicht durch Hydrolyse austauschbar ist.
3. Schleifartikel gemäß Anspruch 2, worin das Polymer Repetiereinheiten umfaßt, und die
Silylgruppen an 0,1 bis 20,0 Mol-% der Repetiereinheiten gebunden sind.
4. Schleifartikel gemäß Anspruch 1, worin der Heißschmelzkleber zudem einen Katalysator
umfaßt.
5. Schleifartikel gemäß Anspruch 1, worin über die Schleifschicht eine zweite Bindemittelschicht
("size layer") aufgetragen ist.
6. Schleifartikel gemäß Anspruch 5, das weiterhin ein antistatisches Material ("supersize")
umfaßt.
7. Verfahren zur Herstellung eines Schleifartikels, umfassend: (a) die Bereitstellung
eines Substrats mit einer ersten Hauptoberfläche, (b) das Auftragen einer Klebstoffschicht,
die einen bei Feuchtigkeit härtbaren Heißschmelzkleber umfaßt, der ein Polymer mit
hydrolysierbaren oder kondensierbaren Silylgruppen umfaßt, auf die erste Hauptoberfläche
des Substrats, wobei der Heißschmelzkleber in einem geschmolzenen oder halb-geschmolzenen
Zustand vorliegt, (c) das Abscheiden von Schleifteilchen auf der Klebstoffschicht,
und (d) das Härten des Heißschmelzklebers.
8. Verfahren gemäß Anspruch 7, worin die Silylgruppen durch
-A-Si(R)
3-m(X)
m
dargestellt werden, worin
A einen zweiwertigen, organischen Rest darstellt;
X eine austretende Gruppe darstellt, die durch Hydrolyse austauschbar ist,
m 1, 2 oder 3 ist, und
R eine Blocking-Gruppe darstellt, die nicht durch Hydrolyse austauschbar ist.
9. Verfahren gemäß Anspruch 7, worin der Klebstoff vor dem Auftragen auf eine Temperatur
von 50 bis 250 °C erwärmt wird.
10. Verfahren gemäß Anspruch 7, worin der Klebstoff in zweiteiliger Form aufgetragen wird,
ein Teil, der ein silanfunktionelles Harz umfaßt, und ein zweiter Teil, der einen
Katalysator umfaßt.
1. Un article abrasif comprenant un substrat présentant une première surface majeure
et une couche adhésive ayant, englobées à l'intérieur, des particules abrasives, appliquée
sur ladite première surface majeure dudit substrat, la couche adhésive comprenant
un adhésif thermofusible comprenant un polymère réticulé via des groupes silyle hydrolysés
ou condensés.
2. L'article abrasif selon la revendication 1, dans lequel lesdits groupes silyle sont
représentés par :
-A-Si(R)
3-m(X)
m
où :
A représente un radical organique bivalent,
X représente un groupe mobile pouvant être déplacé par hydrolyse,
m est égal à 1, 2 ou 3, et
R représente un groupe bloquant ne pouvant être déplacé par hydrolyse.
3. L'article abrasif selon la revendication 2, dans lequel ledit polymère comprend des
unités répétitives et lesdits groupes silyle sont attachés à 0,1 à 20,0 mol% desdites
unités répétitives.
4. L'article abrasif selon la revendication 1, dans lequel l'adhésif thermofusible comporte
en outre un catalyseur.
5. L'article abrasif selon la revendication 1, dans lequel ladite couche abrasive est
revêtue d'une couche de colle.
6. L'article abrasif selon la revendication 5, comprenant en outre une supercolle.
7. Un procédé de préparation d'un article abrasif, le procédé comprenant les étapes consistant
(a) à fournir un substrat présentant une première surface majeure, (b) à appliquer
une couche adhésive, comprenant un adhésif thermofusible durcissable sous atmosphère
humide, contenant un polymère ayant des groupes silyle pouvant être hydrolysés ou
condensés, sur ladite première surface majeure dudit substrat, ledit adhésif thermofusible
étant à l'état fondu ou semi-fondu, (c) à déposer des particules abrasives sur ladite
couche adhésive, et (d) à faire durcir ledit adhésif thermofusible.
8. Le procédé selon la revendication 7, dans lequel lesdits groupes silyle sont représentés
par :
-A-Si(R)
3-m(X)
m
où :
A représente un radical organique bivalent,
X représente un groupe mobile pouvant être déplacé par hydrolyse,
m est égal à 1, 2 ou 3, et
R représente un groupe bloquant ne pouvant être déplacé par hydrolyse.
9. Le procédé selon la revendication 7, dans lequel ledit adhésif est chauffé jusqu'à
une température comprise entre 50 et 250 ° C avant application.
10. Le procédé selon la revendication 7, dans lequel ledit adhésif est appliqué sous forme
de deux parties, une partie comprenant une résine silane fonctionnelle et une seconde
partie comprenant un catalyseur.