Patent ID: 7160936

Claim:
A method of producing an ultraviolet radiation absorbent composition for thermoplastic polymers, said method comprising Step a and Step b; said Step a being a process of iminoesterification of isatoic anhydride and terephthaloyl dichloride in presence of a solvent and an alkali, followed by separating from the reaction mixture a cyclic iminoester compound solid component shown by Formula 1 given below said Step b being a process of treating the solid component separated in said Step a with an alkaline solution and further washing with water to obtain the ultraviolet radiation absorbent composition for thermoplastic polymers containing cyclic imino ester compound shown by Formula 1 in an amount of over 99.5 weight % and less than 100 weight % and having an acid value in the range of 1×10 −3 –1 KOHmg/g and a chlorine ion content in the range of 1×10 −1 –1×10 −3 ppm.