Patent ID: 7592376

Claim:
A prepolymer mixture comprising: a first catalyst component comprising from 1 to 10 parts by weight of a cationic photoinitiator; a second catalyst component comprising from 1 to 10 parts by weight of a free radical photoinitiator chosen from the group consisting of 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2,2-dibutoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxyl-2-methyl-1-phenylpropan-1-one, and 2,2,2-trichloro-1-[4-(1,1-dimethyl)phenyl]ethanone; and a monomer component comprising from 180 to 220 parts by weight, said monomer component consisting essentially of one or more oxetane monomers or epoxide monomers, and wherein the recited parts by weight are based on the total weight of the first catalyst component, the second catalyst component, and the monomer component, and wherein said prepolymer mixture may optionally contain a coloring agent.