represented by the formula CH2 ═C(R) --COO--(CH2 CH2 O)m (CH2)p H(I) wherein R is a hydrogen atom or a methyl group, m is an integer of 2 to 24 and p is an integer of 1 to 16, the formula CH2 ═C(R)--COO--(CH2 CH2 O)q --phenyl--(CH2)r H (II) wherein R is a hydrogen atom or a methyl group, q is an integer of 2 to 24 and r is an integer of 0 to 16, and the fo