Optically clear reinforced silicone elastomers of high optical refractive index and improved mechanical properties for use in intraocular lenses

摘要

Optically clear, reinforced cross-linked silicone elastomers of the invention contain 12 to 18 mol percent of aryl substituted siloxane units of the formula R₄,R₅SiO, end blockers containing silioxane units of the formula R₁R₂R₃SiO, and dialkyl siloxane units of the formula R₆R₇SiO R₁ and R₂ are alkyl, aryl or substituted alkyl or substituted aryl groups, and R₃ is an alkenyl group. R₄ and R₅ are phenyl or mono lower alkyl substituted phenyl groups. R₆ and R₇ are methyl or ethyl groups. The polymer has a degree of polymerization between 100 to 2000, and preferably approximately 250. The polymer also contains trimethyl silyl treated silica as a reinforcer in the weight ratio of approximately 15 to 45 parts of reinforcer to 100 parts of the polymer. After cross-linking, the polymer has properties of an optical refractive index which is at least 1.44, a type A durometer hardness of at least 35, tensile strength of at least 500 psi and tear strength of at least 20 phi. The foregoing properties render the cross-linked polymer especially suitable for forming the bodies of intraocular lenses.