rticularly preferably an acid anhydride group, an epoxy group, an amino group or a carboxylic acid ester group, and Y in the formula (6) is preferably an epoxy group, an amino group or a hydroxyl group. [1411] If X is a hydroxyl group and R3 is a hydrocarbon group of 9 or less carbon atoms, preferably 8 or less carbon atoms, more preferably 7 or less carbon atoms, in the formula (3), the compatibi