CH WHEREIN R1 AND R2 INDEPENDENTLY OF EACH OTHER DENOTES A RESIDUE, OBTAINED BY REMOVAL OF THE CARBOXYL GROUPS, OR AN ALIPHATIC OR CYCLOALIPHATIC POLYCARBOXYLIC ACID HAVING 2 TO 4 CARBOXYL GROUPS, A REPRESENTS THE RESIDUE, OBTAINED BY REMOVAL OF THE TWO HYDROXYL GROUPS, OF A POLYALKYLENE GLYCOL OF AVERAGE MOLECULAR WEIGHT OF AT LEAST 200, AND WHEREIN M AND N DENOTE INTEGERS HAVING A VALUE OF AT LEAST 1 AND AT MOST 3, PREFERABLY 1 OR 2.
WHEREIN R1 AND R2 INDEPENDENTLY OF EACH OTHER DENOTES A RESIDUE, OBTAINED BY REMOVING THE CARBOXYL GROUPS, OF AN AROMATIC POLYCARBOXYLIC ACID HAVING 2 TO 6 CARBOXYL GROUPS, A REPRESENTS THE RESIDUE, OBTAINED BY REMOVING THE TWO HYDROYL GROUPS, OF A POLYALKYLENE GLYCOL OR AVERAGE MOLECULAR WEIGHT OF AT LEAST 200 AND WHEREIN M AND N DENOTE INTEGERS HAVING VALUE OF AT LEAST 1 AND AT MOST 3, PREFERABLY 1 AND 2.