Patent ID: 6277938
Filing Date: 2001-08-21
Classification: C08F,G02B,G11B

Abstract:
A process for the preparation of a non-birefringent optical resin, which comprises copolymerizing a monomer mixture consisting of the monomers (A) to (E) at such a ratio as to give the resin an absolute value of orientational birefringence of less than 1.times.10.sup.-6, the monomers being:(A) 5 to 40 wt % of a methacrylic or acrylic ester having a C.sub.5 -C.sub.22 aliphatic hydrocarbon group in the ester moiety;(B) 50 to 80 wt % of methyl methacrylate;(C) 5 to 40 wt % of an N-substituted maleimide;(D) 4 to 20 wt % of benzyl methacrylate; and(E) 0 to 10 wt % of a monomer copolymerizable with said monomers.