Patent ID: 6486237
Filing Date: 2002-11-26
Classification: C08G,C08K,C08L

Abstract:
A silicone composition crosslinkable by hydrosilylation into an adhesive and cushioning gel, comprising:(I)â€”at least one polyorganosiloxane POS (I) comprising: end siloxyl units of formula M=(R)2(Hrf)SiO1/2, at a level of 0.1 to 1 molar %, â€ƒwherein: R=CH3 and Hrf=vinyl, and identical or different siloxyl units of formula D=(R1)p(Hrf)qSiO2/2, at a level of 99 to 99.9 molar %, wherein R1=CH3, p=2 and q=0, (II)â€”at least one polyorganosiloxane POS (II) comprising: identical or different siloxyl units of formula R2SiO2/2, wherein R is a linear C1-C6 alkyl group, or an aryl group, optionally substituted, end siloxyl units M=(Hrf)s(R2)tSiO1/2, at a level of 1 to 6 molar %, wherein units Hrf=H, R2=CH3, s=1 and t=2 identical or different siloxyl units D=(Hrf)u(R3)vSiO2/2, at a level of 10 to 50 molar %, wherein units R3=CH3, Hrf=H, u=1 and v=1 â€ƒwith the further proviso that at least one of the D units of the POS (II) carries an Hrf (u=1, v=1), (III)â€”at least one adhesion promoter (III), selected from the group consisting of: extending polyorganosiloxanes POS (III) exhibiting: end siloxyl units M=(Hrf)w(R4)xSiO1/2, at a level of 8 to 20 molar %, wherein units Hrf=H, R4=CH3, w=1 and x=2, with the further proviso that the Hrfs of the POS (III) react at least with the Hrfs of the end M units of the POS (I), that the ratio: r1=number&it;â€ƒ&it;of&it;â€ƒ&it;Hrf&it;â€ƒ&it;groups&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(III)&it;â€ƒnumber&it;â€ƒ&it;of&it;â€ƒ&it;Hrf&it;â€ƒ&it;groups&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(II)&it;â€ƒ&it;and&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(III)Ã—100â€ƒis less than or equal to 95%, and that the ratio: r2=number&it;â€ƒ&it;of&it;â€ƒ&it;Hrf&it;â€ƒ&it;groups&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(II)&it;â€ƒ&it;and&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(III)number&it;â€ƒ&it;of&it;â€ƒ&it;Hrf&it;â€ƒ&it;groups&it;â€ƒ&it;in&it;â€ƒ&it;the&it;â€ƒ&it;POS&it;â€ƒ&it;(I)â€ƒis less than or equal to 0.9; and siloxyl units D=(R5)2SiO2/2, at a level of 80 to 92 molar %, wherein units R5=CH3, organosilanes comprising, per molecule, at least one C2-C6 alkenyl group, of the following formula (III-2-1) â€ƒwherein R1, R2 and R3 are hydrogen or hydrocarbonaceous radicals which are identical to or different from one another, U is a linear or branched C1-C4 alkylene or a divalent group of formula â€”COâ€”O-alkylene- wherein the alkylene group has the definition given above and is connected to the Si atom, R4 and R5, which are identical or different, are a linear or branched C1-C4 alkyl group, xâ€²=0 or 1, x=0 to 2, preferably 0 or 1 and more preferably still 0 and organosilicon compounds comprising at least one epoxy group. (IV)â€”organic hollow microspheres, (V)â€”at least one linear polyorganosiloxane POS (V) comprising end siloxyl units M=(R6)3SiO1/2 and siloxyl units D=(R7)2SiO2/2 wherein R6 and R7 identical different from one another have the same definition as R, and having a lower dynamic viscosity than that of the POS (I), and (VI)â€”an effective amount of hydrosilylation catalyst.