Patent ID: 8158329

Claim:
A compound represented by the formula (I): wherein P 1 , P 2 , P 3 , P 4 and P 5 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, a C3-C8 cycloalkyl group, a C6-C12 aryl group or a C7-C12 aralkyl group, and P 1 and P 2 may be bonded each other to form a C3-C12 divalent acyclic hydrocarbon group which forms a ring together with the carbon atoms to which they are bonded, and P 4 and P 5 may be bonded each other to form a C3-C12 divalent acyclic hydrocarbon group which forms a ring together with the carbon atom to which they are bonded, and least one selected from the group consisting of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 9 is the group represented by the formula (II): wherein X 1 and X 2 each independently represent a hydrogen atom or a C1-C4 alkyl group, n represents an integer of 1 to 4, Z 1 represents a C1-C6 alkyl group or a C3-C12 cycloalkyl group, and ring Y represents an alicyclic hydrocarbon group, and the others each independently represent a hydrogen atom, a C1-C6 alkyl group or a hydroxyl group.