Optically clear filled silicone elastomers
AssigneeAmerican Optical Corporation
InventorEdward A. Travnicek
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Abstract
Reinforced silicone elastomers, having improved tensile strength and particularly tear strength, include at least copolymers of aryl siloxanes and alkyl siloxanes, in a ratio of aryl to alkyl substituents providing 6 to 16 mole percent phenyl chosen to provide a refractive index matched to the index of refraction of a silica filler, form optically clear material useful for soft contact lenses. Preferably two copolymers are used and each has methyl groups with 6 to 16 mole percent phenyl groups. One of the two copolymers contains terminal vinyl groups and the other copolymer contains terminal (R).sub.2 HSi--O-- groups. Platinum materials are used to catalyze the vulcanization of the copolymer mix. These elastomers are useful for a variety of optical products, e.g., contact lenses, intraocular implants and the like.
Claims6
An optically clear, reenforced vulcanized silicone elastomer comprising 80 to 95% by weight of
- a. a copolymer comprising
- i. dimethyl siloxane,
- ii. diphenyl siloxane, or phenylmethyl siloxane or mixtures thereof, and
- iii. vinyl siloxane;
- b. a copolymer comprising
- i. dimethyl siloxane,
- ii. diphenyl siloxane or phenylmethyl siloxane or mixtures thereof, and
- iii. siloxane having (R).sub.2 HSiO-- or --O--SiHR--O--
- groups, or both, wherein R is methyl or ethyl;
- with the proviso that each of fractions (a) and (b) has 6 to 16 mole percent phenyl and each contains no Part (iii) of the other;
- c. 5 to 20% of a silica filler, the refractive index of said copolymer being substantially the same as the index of refraction of (c).
Dependencies are inferred from the claim text.