Process for producing a contact lens

Claim 1

A process for producing a contact lens comprising the steps of: polymerizing a monomer mixture containing a siloxanylalkyl ester monomer within Group I shown below, a vinyl monomer within Group II or Group III shown below in the presence of a crosslinking agent within Group IV shown below by exposure to gamma ray radiation at a temperature between -100° C. and 0° C.; and forming resulting polymer into a contact lens by working on a lathe; said Groups I, II, III and IV being defined as follows: Group I: a siloxanylalkyl methacrylate or acrylate monomer represented by the following general formula: ##STR6## where A, R 1 , R 2 , R 3 , R 4 , and R 5 are each a methyl or phenyl group; R 6 is a hydrogen atom or a methyl group; a and b are each an integer of 0. to 3; c and d are each an integer of 0 to 2; and e is 0 or 1; Group II: a methacrylate or acrylate monomer represented by the following formula: ##STR7## where R 1 is a hydrogen atom or a methyl group; R 2 is a methylene or oxymethylene unit; R 3 is one member selected from the group consisting of methyl, ethyl, propyl, cyclohexyl, phenyl, fluorine-containing alkyl and fluorine-containing aryl groups; and n is an integer of 0 to 14; Group III: a compound represented by the following formula, or N-vinylpyrrolidone: ##STR8## where R is a hydrogen atom or a methyl group; and n is an integer of 0 to 14, an m is 0 when n is 0 and 1 when n is more than 1; and Group IV: a crosslinking agent represented by the following formula: ##STR9## where R 1 is a hydrogen atom or a methyl group; R 2 is one member selected from the group consisting of --CH 2 --CH 2 --0--, ##STR10## R 3 is one member selected from the group consisting of CH 3 --, CH 3 CH 2 -- and -CH 2 OH; and y is an integer of 1 to 14.