Inventors:
Helmut Singer - Northboro MA
Ellen Bellantoni - Natick MA
Albert R. LeBoeuf - San Diego CA
Assignee:
CIBA Vision Care Corp. - Atlanta GA
International Classification:
C08J 300
Abstract:
In the particular embodiment described in the specification, a contact lens hydrogel is prepared by copolymerizing 75 parts of N-vinyl pyrrolidone and 23 parts of phenyl ethyl methacrylate together with allyl methacrylate as a crosslinker, t-butyl peroctoate as a thermal initiator and 2,2-dimethoxy-2-phenylacetophenone or benzoin methyl ether as a photoinitiator. The mixture is maintained at a temperature of 5. degree. C. and protected from light prior to photopolymerization which is carried out under ultraviolet radiation. The copolymer is then post-cured thermally. Cloudy or hazy hydrogels are avoided by preventing prepolymerization of the mixture.