R2, R3, and R4 are each independently an alkyl group which may have a substituent, an aryl group which may have a substituent, or a halogen atom; a and b are each independently an integer of 0 to 4; c and d are each independently an integer of 0 to 3; and l is an integer of 0 or 1, and when l=1, Y is a straight-chain alkylene group having 2 to 12 carbon atoms, a substituted or unsubstituted branch