Patent ID: 8481640

Claim:
A water-insoluble hydrophilic polymer network comprising polyorganosiloxane polyoxyalkylene block copolymer moieties of the form PS-(A-PO) m -(A-PS) n or PS-(A-PO-A-PS) n wherein PS represents a polyorganosiloxane block with a degree of polymerization of 10 to 30, PO represents a polyoxyethylene block with a degree of polymerization of from 4 to 40 oxyethylene units, A represents a divalent radical and m and n have a value of at least 1, wherein the sum of the degree of polymerization of the polyorgansiloxane blocks and the degree of polymerization of the polyoxyethylene block in the block copolymer are each in the range 15 to 35, wherein at least three polysiloxane polyoxyalkylene block copolymer moieties are linked to each other through an organosilicon cross-linking moiety selected from a branched siloxane comprising one or more Q units of the formula (SiO 4/2 ), from 0 to 250 D units of the formula R b 2 SiO 2/2 and M units of the formula R a R b 2 SiO 1/2 , wherein the R a and R b substituents are selected from alkyl and alkenyl groups having 1 to 6 carbon atoms, at least three R a substituents in the branched siloxane being alkenyl units, provided that the cross-linking moiety forming the links between polyorganosiloxane polyoxyalkylene block copolymer moieties result from an addition reaction between silicon-bonded hydrogen atoms cross-linking sites present on the polyorganosiloxane polyoxyalkylene block copolymer and the alkenyl groups present on the branched siloxane prior to formation of the hydrophilic polymer network.