Patent ID: 6908998

Claim:
A method of producing an ultraviolet radiation absorbent, said method comprising Step A, Step B and Step C; said Step A being a process of causing an amidation of anthranilic acid and terephthaloyl dichloride in the presence of a solvent and an alkali to generate N,N′-bis(o-carboxyphenylterephthalamid) and separating a solid component containing N,N′-bis(o-carboxyphenylterephthalamid) generated by said amidation; said Step B being a process of separating a solid component containing cyclic imino ester compound shown by Formula 1 by iminoesterification within the solid component separated in said Step A, in the presence of acetic anhydride and a solvent; and said Step C being a process of treating with an alkaline solution and further washing with water the solid component generated and separated in said Step B to obtain the ultraviolet radiation absorbent for thermoplastic polymers containing the cyclic imino ester compound shown by Formula 1 given below in an amount of over 99.5 weight % and less than 100 weight % and having an acid value in the range of 1×10 −1 -1 KOHmg/g or a chlorine ion content in the range of 1×10 −1 -1×10 3 ppm.