Concretely speaking, it is desired to use the compounds represented by the following formulas (3), (4) and (5) ##STR14## wherein R1 and R2 are alkyl groups which together may form a cyclohexane ring, and R3 is an alkyl group or a hydrogen atom, ##STR15## wherein R4 is the same or different and is a methyl group, a methoxy group or a chlorine atom, e is 2 or 3, and R5 is phenyl group or methoxy gro