Stabilization of plastic having ester group

PURPOSE: To stabilize ester-containing plastic against the deterioration due to heat and hydrolysis by reacting polyester having a functional group with specific sterically hindered carbodiimide. CONSTITUTION: Polyester-containing plastic having a functional group (A) is reacted with sterically hindered carbodimide represented by formula [wherein A, B and D are each 6-20C aromatic (aliphatic) hydrocarbon and characterized by that a carbodiimide group is bonded to an aromatic ring carbon atom (i) and an aromatic ring position ortho to the carbodiimide group has two or more carbon atoms and substituted by an aromatic, aliphatic and/or cyclic substituent (ii) and, further, A, D are provided so that an NCO group is bonded to an aromatic cyclic carbon and n is 0-3] to stabilize the component A. COPYRIGHT: (C)1993,JPO