Patent ID: 7452655

Claim:
An acrylic copolymer comprising: a recurring unit of the following formula (1), a recurring unit of the following formula (2), wherein R represents a hydrogen atom or a methyl group; R 1 individually represents a hydrogen atom, hydroxyl group, or —COOR 3 group, wherein R 3 is a hydrogen atom, a linear or branched alkyl group having 1-4 carbon atoms or an alicyclic alkyl group having 3-20 carbon atoms, provided that at least one of R 1 groups is not a hydrogen atom, and a recurring unit of the following formula (3), wherein any two of R 2 groups form, in combination and together with the carbon atom to which the two R 2 groups bond, a divalent alicyclic hydrocarbon group having 4-20 carbon atoms or a derivative thereof, with the remaining R 2 being a linear or branched alkyl group having 1-4 carbon atoms, a monovalent alicyclic hydrocarbon group having 4-20 carbon atoms, or a derivative thereof.