US Patent 7261845 Plastic lens and process for preparing the lens

A plastic lens which absorbs ultraviolet light having wavelength of about 400 nm and suppresses coloring and a process for producing the lens. A plastic lens may be made from a composition which comprises (A) a lens material monomer comprising diethylene glycol bisallylcarbonate, (B) an organic peroxide-based polymerization initiator, (C) a cobalt compound represented by at least one of CoO.Al2O3 and Co.Al2O4, and (D) at least one ultraviolet light absorbent selected from 2-hydroxy-4-octyloxy-benzophenone, 2,2′,4,4′-tetrahydroxy-4-octyloxybenzophenone and 2,2′,4′-trihydroxy-4-octyloxybenzophenone. A process for producing a plastic lens comprises mixing component (A), component (B), a cobalt fluid comprising component (C) in a dispersant and component (D) and a step of casting the mixed fluid into a mold and polymerizing the fluid to obtain a plastic lens.