tuent, shown by R1 in the general formula [2], when A1 in the general formula [1] is a group shown by the general formula [3], and A2in the above-described general formula [3] is a direct-linkage or a ???C(CF3)2??? group, may be straight chained, branched or cyclic, and includes one having preferably 3 to 8 carbon atoms, which is specifically exemplified by the same as examples of the alkyl group