Polymers for contact lenses

Abstract

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.

Dependencies are inferred from the claim text.