Patent ID: 7759451

Claim:
A fumaric diester copolymer, comprising: a fumaric diester residue unit represented by the following general formula (1), and a (meth)acrylic ester residue unit represented by the following general formula (2), the copolymer having a number average molecular weight of from 1,000 to 500,000, wherein R 1 and R 2 each independently represents a linear alkyl group having from 1 to 6 carbon atoms, a branched alkyl group having from 1 to 6 carbon atoms, or a cyclic alkyl group having from 3 to 6 carbon atoms, wherein R 3 represents hydrogen or methyl group, R 4 represents hydrogen, a linear alkyl group having from 1 to 4 carbon atoms, or a branched alkyl group having from 1 to 4 carbon atoms, and n is 1 or 2.