Patent ID: 7193030

Claim:
An acid anhydride of the formula (4), wherein anhydrides are substituted at sites 3 or sites 4, —O—X—O— is formed of a structure defined by the formula (2), in which R 1 , R 2 , R 3 , R 7 and R 8 may be the same or different and represent a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group and R 4 , R 5 and R 6 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group, —[Y—O]— is an arrangement of one kind of structure defined by the formula (3) or a random arrangement of at least two kinds of structures defined by the formula (3), in which R 9 and R 10 may be the same or different and represent a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group and R 11 and R 12 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group, and each of a and b is an integer of 0 to 30, provided that at least one of a and b is not 0, which acid anhydride is obtained from, as a raw material, a bifunctional phenylene ether oligomer having a number average molecular weight of 500 to 3,000, represented by the formula (1), wherein —O—X—O—, —[Y—O]—, a and b are as defined in the formula [4].