Polyester resin composition

1. A polyester resin composition comprising a compound represented by the following formula (1) and a polyester resin:

wherein

each of R 1a , R 1b , R 1c , R 1d and R 1e independently represents a hydrogen atom or a monovalent substituent excluding OH, at least one substituents represents a substituent having a positive Hammett's σp value, and substituents may combine with each other to form a ring; and

each of R 1g , R 1h , R 1i , R 1j , R 1k , R 1m , R 1n and R 1p independently represents a hydrogen atom or a monovalent substituent, and substituents may combine with each other to form a ring, and

wherein the polyester resin is at least one member selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate.

2. The polyester resin composition as claimed in claim 1 , wherein the monovalent substituent is a halogen atom, a substituted or unsubstituted alkyl group having a carbon number of 1 to 20, a cyano group, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted alkylcarbonyl group, a nitro group, a substituted or unsubstituted amino group, a hydroxy group, an alkoxy group having a carbon number of 1 to 20, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted sulfamoyl group, a thiocyanate group, or a substituted or unsubstituted alkylsulfonyl group, and in the case where the monovalent substituent has a substituent, the substituent is a halogen atom, an alkyl group having a carbon number of 1 to 20, a cyano group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylcarbonyl group, a nitro group, an amino group, a hydroxy group, an alkoxy group having a carbon number of 1 to 20, an aryloxy group, a sulfamoyl group, a thiocyanate group, or an alkylsulfonyl group.

3. The polyester resin composition as claimed in claim 1 , wherein at least one of R 1b , R 1c and R 1d is a substituent having a positive Hammett's σp value.

4. The polyester resin composition as claimed in claim 1 , wherein the Hammett's σp value is from 0.1 to 1.2.

5. The polyester resin composition as claimed in claim 1 , wherein the substituent having a positive Hammett's σp value is a group selected from COOR r , CONR s 2 , CN, CF 3 , a halogen atom, NO 2 , and SO 3 M, wherein each of R r and R s independently represents a hydrogen atom or a monovalent substituent, and M represents a hydrogen atom or an alkali metal.

6. The polyester resin composition as claimed in claim 1 , wherein the substituent having a positive Hammett's σp value is COOR r or CN, wherein R r represents a hydrogen atom or a monovalent substituent.

7. The polyester resin composition as claimed in claim 1 , wherein R 1h or R 1n is a hydrogen atom.

8. The polyester resin composition as claimed in claim 1 , wherein each of R 1g , R 1h , R 1i , R 1j , R 1k , R 1m , R 1n and R 1p is a hydrogen atom.

9. The polyester resin composition as claimed in claim 1 , wherein pKa of the compound represented by formula (1) is from −5.0 to −7.0.

10. The polyester resin composition as claimed in claim 1 , containing the compound represented by formula (1) in an amount of 0.01 to 30% by mass.

11. The polyester resin composition as claimed in claim 1 , further comprising an additive.

12. The polyester resin composition as claimed in claim 1 , wherein the polyester resin is polyethylene terephthalate.

13. The polyester resin composition as claimed in claim 11 , wherein the additive is an ultraviolet absorber, a light stabilizer, an antioxidant, a heat stabilizer, a fluorescent brightener or a flame retardant.

14. A polyester resin molded article comprising the polyester resin composition claimed in claim 1 , wherein the thickness of resin molded article is from 0.1 μm to 25 mm.

15. A photovoltaic backsheet comprising the polyester resin composition claimed in claim 1 .

16. A photovoltaic front sheet comprising the polyester resin composition claimed in claim 1 .

17. A window film comprising the polyester resin composition claimed in claim 1 .

18. A packaging film for food or medical use comprising the polyester resin composition claimed in claim 1 .

19. An agricultural film comprising the polyester resin composition claimed in claim 1 .

20. An optical film comprising the polyester resin composition claimed in claim 1 .

21. A fiber comprising the polyester resin composition claimed in claim 1 .

22. A photovoltaic module comprising the polyester resin composition claimed in claim 1 .

23. The polyester resin composition as claimed in claim 5 , wherein the polyester resin is at least one member selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate.

24. The polyester resin composition as claimed in claim 6 , wherein the polyester resin is at least one member selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate.

25. The polyester resin composition as claimed in claim 5 , wherein the polyester resin is polyethylene terephthalate.

26. The polyester resin composition as claimed in claim 6 , wherein the polyester resin is polyethylene terephthalate.