. . "y have a hydroxyl group, an ether group, an ester group, a (meth)acryloyl group, an epoxy group or an allyl group, a phenyl group, a phenoxy group and a thiophenoxy group), each of R1 to R5 is a group selected from a hydrogen atom, a hydroxyl group, a C1 -C15 aliphatic group, a halogen atom, a nitro group, an alkoxy group, a phenyl group and a group represented by the formula (5), n is 1 to 4, Z i" . .