POLYMERS FOR CONTACT LENSES

摘要

The present invention relates to a thermoplastic polyurethane contact lens prepared from a mixture comprising: (a) at least one polyethylene glycol; (b) at least one di-isocyanate; and (c) at least one diol of formula (I): wherein n is an integer from 1 to 25; wherein the polyethylene glycol, di-isocyanate and diol are reacted under substantially anhydrous conditions. Further aspects of the invention relate to a process for preparing a contact lens. 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 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; (iii) injection molding the polyurethane xerogel to form a molded article, (iv) hydrating the xerogel molded article to form a contact lens.