ula (III), general formula (I), ##STR17## wherein R1 and R2 may be the same or different and are hydrogen atoms or methyl groups, and A is the same or different alkylene group, oxyalkylene group, or a group of the following formula which may be substituted, ##STR18## wherein R3 is a hydrogen atom or a methyl group, X is a halogen atom, k and m are integers of from 0 to 1, a is an integer of from 0