Hydroxymethyl-substituted polyfunctional phenols

Hydroxymethyl-substituted polyfunctional phenols, expressed by the following structure: (wherein X represents: bivalent group (a) expressed by the following structure: (wherein R1, R2, R3 and R4 each independently represent a hydrogen atom or an alkyl group with a carbon atom number of 1 through 4); quadrivalent group (b) expressed by the following structure: (wherein R5 and R6 each independently represent a hydrogen atom or an alkyl group with a carbon atom number of 1 through 4); or bivalent group (c) expressed by the following structure: (wherein R7 and R8 each independently represent a hydrogen atom or a monofluoromethyl, difluoromethyl or trifluoromethyl group; however, R7 and R8 cannot be both hydrogen atoms); wherein n takes 2 when X is bivalent group (a), takes 4 when X is quadrivalent group (b), or takes 2 when X is bivalent group (c)).