Patent ID: 7704669

Claim:
An acrylic polymer comprising a recurring unit (i) represented by the following formula (1), a recurring unit (ii) represented by the following formula (2), and an acid-labile group-containing recurring unit (iii) which contains at least one unit selected from a recurring unit represented by the following formula (3) and formula (4), wherein, in the formulas (1) to (4), R, R′, R″, and R′″ individually represent a hydrogen atom, methyl group, or trifluoromethyl group, in the formula (1), R 1 represents a hydrogen atom, linear or branched alkyl group having 1-4 carbon atoms, linear or branched alkoxyl group having 1-4 carbon atoms, or linear or branched fluoroalkyl group having 1-4 carbon atoms, in the formula (2), X represents a polyalicyclic hydrocarbon group consisting only of carbon and hydrogen which is one group selected from groups represented by the following formulas (2a) to (2l): in the formula (3), R2 and R3 individually represent a linear or branched alkyl group having 1-4 carbon atoms and R4 represents an alicyclic hydrocarbon group having 4-20 carbon atoms, and in the formula (4), R5 represents a linear or branched alkyl group having 1-4 carbon atoms, R6 and R7 individually represent a hydrogen atom or a linear or branched alkyl group having 1-4 carbon atoms, and n represents an integer of 3-7.