Novel polysiloxane-polyurethanes and contact lens thereof

Claim 1

A siloxane-urethane polymer, suitable for use as an oxygen permeable membrane or an ophthalmic device, having based on total urethane groups 50 to 80% of --C--NH--COO--C-- groups and 50 and 20% of --C--NH--COO--Si-- groups, which consists essentially of the polymerization product of (a) 80-95% weight (based on the total polymer) of a poly-isocyanate capped, linear or branched polysiloxane prepolymer, having a molecular weight of about 1000 to about 10,000 and containing at least one isocyanate group per 3000 molecular weight unit of polysiloxane, said isocyanate groups being attached to the polysiloxane through urethane linkages, said polysiloxane prepolymer having the structure A 1 , A 2 and A 3 ##STR8## wherein: R 1 is a linear or branched alkylene group with 2-6 carbon atoms or a polyoxyalkylene group of structures ##STR9## wherein R 3 is hydrogen or methyl and p is an integer from 1-50; R 2 , R a , R b , R c , R d , R e , R f , R g , R h , R i , R j , R k are independently methyl or phenyl; x 1 , x 2 are integers from 1 to 500 with the proviso that the sum of x 1 +x 2 is 12 to 1,000; y 1 is 0 to 4 and y 2 is 2 to 5 with the proviso that the respective ratios of ##EQU3## are not greater than 70, ##STR10## wherein T 1 is A 1 from which X 1 removed, and T 3 is A 3 from which X 3 is removed, R 4 is a di-radical obtained by removing NCO-groups from an aliphatic, cycloaliphatic or aromatic di-isocyanate; and (b) 20-50% by weight (based on the total polymer) of a linear polydialkyl- or polydiphenyl-siloxane disilanol in ##STR11## having a molecular weight from about 240 to about 1000 and containing terminal siloxanol groups, where, n is 2-50 and E a and E b are alkyl of 1 to 4 carbon atoms or phenyl.