by general formulas vii a to vii e in the formula each of r 91 and r 92 independently represents an alkyl group having 1 to 10 carbon atoms an alkoxy group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms but in general formula vii a the compound in which r 91 represents an alkyl group having 3 carbon atoms and r 92 represents an alkyl group having 2 carbon atoms is excluded in the case where a compound selected from the group represented by general formulas vii a to vii d is contained one kind to 10 kinds thereof are preferably contained one kind to 8 kinds thereof are particularly preferably contained one kind to 5 kinds thereof are particularly preferably contained two kinds or more thereof are also preferably contained and the content in this case is preferably in the range of 5 to 40 still more preferably in the range of 5 to 35 and particularly preferably in the range of 7 to 30 each of r 91 and r 92 preferably independently represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms more preferably represent an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms and in the case where r 91 and r 92 represent alkenyl groups the following structures are preferable in the formula the right terminal is bonded to a ring structure the following structure is particularly preferable in the formula the right terminal is bonded to a ring structure moreover r 91 and r 92 may be the same.