Grindable silicone elastomer composition and the use thereof
Temporary adhesive compositions used to adhesively bond a substrate to be abraded or polished onto a substrate are themselves abradable or polishable, and contain a non-reinforcing filler or particulate silicone resin in a curable organopolysiloxane composition, and have defined physical characteristics in addition to being thermally stable.
1. A process for adhesively fastening and finishing workpieces, comprising:
a) applying a crosslinkable silicone-elastomer adhesive to at least one workpiece to be fastened;
b) contacting the workpieces such that the crosslinkable silicone elastomer adhesive is between surfaces of the workpiece to be fastened;
c) curing the crosslinkable silicone elastomer adhesive, wherein the adhesive, following curing, has a ratio of dynamic viscosities at the shear rates of 1 s −1 and 100 s −1 at room temperature of not more than 1.2, the crosslinked silicone rubber has a Shore A hardness according to DIN 53505 of between 30 and 95, a tear propagation resistance according to ASTM D624-B-91 of not more than 4 N/mm, an elongation at break according to DIN 53504-85S1 of not more than 150%, and a tensile strength according to DIN 53504-85S1 of not more than 3 N/mm 2 to form fastened workpieces; and
d) sanding and/or polishing at least a surface of the fastened workpieces having exposed cured adhesive,
e) parting adhesive from the fastened workpieces.
2. The process of claim 1 , wherein the crosslinkable silicone elastomer composition is an addition-crosslinking composition.
3. The process of claim 2 , wherein besides (E) the addition-crosslinking silicone elastomer composition comprises the following components
(A) 20-60% by weight of linear compound(s) containing radicals having aliphatic carbon-carbon multiple bonds,
(B) 1-10% by weight of linear organopolysiloxanes having Si-bonded hydrogen atoms
or instead of (A) and (B)
(C) 30-60% by weight of linear organopolysiloxane(s) containing SiC-bonded radicals having aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms, and
(D) at least one hydrosilylation catalyst.
4. The process of claim 1 , wherein the crosslinkable silicone elastomer composition is a condensation-crosslinking composition.
5. The process of claim 1 , wherein the crosslinkable silicone elastomer composition is a peroxide-crosslinking composition.
6. The process of claim 1 , wherein the cured adhesive has a Shore A hardness between 40 and 80.
7. The process of claim 1 , wherein the crosslinkable silicone elastomer adhesive contains a non-reinforcing filler.
8. The process of claim 7 , wherein the reinforcing filler comprises aluminum oxide.
9. The process of claim 1 , wherein the crosslinkable silicone elastomer adhesive contains a branched silicone resin.