The aryl group of the aryl group which may have a substituent, shown by R10 and R11 includes one having generally 6 to 16 carbon atoms, preferably 6 to 10 carbon atoms, which is specifically exemplified by the same as examples of the aryl group of the aryl group which may have a substituent, shown by R1 in the above-described general formula [2], and among others, a preferable one includes, for ex