POLYMERS FOR CONTACT LENSES

摘要

The present invention relates to a polyurethane prepared from a mixture comprising:
(a) at least one polyethylene glycol;
(b) at least one di-isocyanate;
(c) at least one polydialkyl siloxane diol; and
(d) at least one diol of formula I
wherein n is an integer from 1 to 25;
wherein the polyethylene glycol, di-isocyanate, polydialkyl siloxane diol and diol are reacted under substantially anhydrous conditions. Further aspects of the invention relate to a process for preparing a polyurethane. The invention also relates to a process for preparing a polyurethane xerogel in the form of a molded article, said process comprising the steps of:
(i) preparing a reaction mixture comprising at least one polyethylene glycol,
at least one di-isocyanate, at least one polydialkyl siloxane diol and at least one diol of formula I as described above;
(ii) reacting the reaction mixture formed in step (i) under substantially anhydrous conditions to form a polyurethane xerogel; and
(iii) injection molding the polyurethane xerogel to form a molded article.