A compound of the formula (1): ##STR00001## wherein PCA represents a polycycloaliphatic hydrocarbon group, ALK represents a divalent aliphatic hydrocarbon group, m is 1 or 2, n is 0 or 1, and R1 and R2 represent independently each other an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group or an aryloxy group.