Patent ID: 7407733

Claim:
A polymeric compound containing at least one monomer unit represented by the following formula (I); wherein R a is a hydrogen atom, a halogen atom, an alkyl group of 1 to 6 carbon atoms or an haloalkyl group of 1 to 6 carbon atoms; each of R 1 and R 2 is identical to or different from a hydrogen atom or a hydrocarbon group, provided that at least one of R 1 and R 2 is a hydrocarbon group; R 1 and R 2 may be bonded together to form a ring with an adjacent carbon atom; and each of R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 9 is identical to or different from a hydrogen atom or a hydrocarbon group, and wherein a content of the monomer unit represented by the formula (I) is 10 to 90 mole-% and a weight-average molecular weight (Mw) of the polymeric compound is 5000 to 50,000.