Patent ID: 6265497
Filing Date: 2001-07-24
Classification: C08G,C08L,C09D

Abstract:
An alkenyl-containing siloxane copolymer prepared by a process comprising:in a first step, reactinga compound (1) having at least three aliphatic double bonds, of the general formulaR.sup.2 (CR.sup.3.dbd.CH.sub.2).sub.xwhereR.sup.2 is a trivalent or tetravalent hydrocarbon radical having 1 to 25 carbon atoms per radical, or is a trivalent or tetravalent silane radical,R.sup.3 is a hydrogen atom or an alkyl radical, andx is 3 or 4 withan organosiloxane (2) having terminal Si-bonded hydrogen atoms in the presence of catalyst (3) which promotes the addition of Si-bonded hydrogen onto aliphatic double bond,the ratio employed of Si-bonded hydrogen in the organosiloxane (2) to aliphatic double bond in organic compound (1) being from 1.3 to 10,in a second step, reactingthe resulting hydrocarbon-siloxane copolymers containing Si-bonded hydrogen atoms withan .alpha.,.omega.-dialkenylsiloxane polymer (4) having an average molecular weight of from 1000 Dalton to 15,000 Daltons in the presence of catalyst (3) which promotes the addition of Si-bonded hydrogen onto aliphatic double bond,the ratio employed of aliphatic double bond in the .alpha.,.omega.-dialkenylsiloxane polymer (4) to Si-bonded hydrogen in the hydrocarbon-siloxane copolymer being from 1.2 to 10,and, if desired, in a third stepequilibrating the resulting alkenyl-containing siloxane copolymers with at least one organopolysiloxane (5) selected from the group consisting of linear organopolysiloxanes containing terminal triorganosiloxy groups, linear organopolysiloxanes containing terminal hydroxyl groups, branched organopolysiloxanes optionally containing hydroxyl groups, cyclic organopolysiloxanes, and copolymers of diorganosiloxane units and monoorganosiloxane units.