Polyester resin composition and process for the preparation thereof

1. A polyester resin composition comprising:

a thermoplastic polyester resin and

a polyether compound-treated layered material consisting of polyether and layers respectively exfoliated by one another,

which satisfies at least one of the conditions (i) to (iii) given below:

(i) That said polyether compound is represented by the general formula (2):

 wherein -A- is —O—, —S—, —SO—, —SO 2 —, —CO—, an alkylene group containing 1 to 20 carbon atoms or an arylene group containing 6 to 20 carbon atoms, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 each represents a hydrogen atom, a halogen atom or a univalent hydrocarbon group containing 1 to 5 carbon atom, R 9 and R 10 each represents a bivalent hydrocarbon group containing 1 to 5 carbon atoms, R 11 and R 12 each represents a hydrogen atom or a univalent hydrocarbon group containing 1 to 20 carbon atoms, those may be the same or different, and m and n each represents the number of occurrences of the repeating oxyalkylene group provided that 2≦m+n≦50;

(ii) That said polyester resin composition comprises a phosphorus-containing compound;

(iii) That said polyester resin composition is obtainable by melt-kneading the thermoplastic polyester resin and the polyether compound-treated layer material consisting of polyether and layers respectively exfoliated by one another and then treating the mixture for increasing the molecular weight of the polyester resin.

2. The polyester resin composition according to claim 1 ,

wherein the phosphorus-containing compound comprises at least one member selected from the group consisting of a phosphorus-containing stabilizer and a phosphorus-containing flame retardant.

3. The polyester resin composition according to claim 2 ,

wherein the phosphorus-containing stabilizer is a phosphite compound.

4. The polyester resin composition according to claim 2 ,

wherein the phosphorus-containing flame retardant comprises at least one member selected from the group consisting of a phosphate ester compound and a red phosphorus compound.

5. The polyester resin composition according to claim 1 ,

wherein the polyether compound-treated layered material consisting of polyether and layers respectively exfoliated by one another is obtainable by blending the layered material with the polyether compound in water or a water-containing polar solvent.

6. The polyester resin composition according to claim 1 ,

wherein the polyether compound is soluble in water or a water-containing polar solvent.

7. The polyester resin composition according to claim 1 ,

wherein the layered materials having an equivalent area circle diameter [D] of not larger than 3000 angstroms account for not less than 20% of the layered material in the polyester resin composition.

8. The polyester resin composition according to claim 1 ,

wherein the mean value of the equivalent area circle diameters [D] of the layered materials in the polyester resin composition is not larger than 5000 angstroms.

9. The polyester resin composition according to claim 1 ,

wherein the mean layer thickness of the layered materials in the polyester resin composition is not more than 500 angstroms.

10. The polyester resin composition according to claim 1 ,

wherein the maximum layer thickness of the layered materials in the polyester resin composition is not more than 2000 angstroms.

11. The polyester resin composition according to claim 1 ,

wherein the [N] value of the layered materials in the polyester resin composition is not less than 30,

the [N] value being defined as the number of particles per unit weight proportion of the layered material as occurring in an area of 100 μm 2 of the polyester resin composition.

12. The polyester resin composition according to claim 1 ,

wherein the mean aspect ratio (layer length/layer thickness ratio) of the layered materials in the polyester resin composition is 10 to 300.

13. The polyester resin composition according to claim 1 , wherein the layered material is a layered phyllosilicate.

14. A method of producing a polyester resin composition comprising a thermoplastic polyester resin and a polyether compound-treated layered material consisting of polyether and layers respectively exfoliated by one another

which comprises melt-kneading the thermoplastic polyester resin and the polyether compound-treated layered material consisting of polyether and layers respectively exfoliated by one another

and then treating the mixture for increasing the molecular weight of the polyester resin.

15. The method of producing a polyester resin composition according to claim 14 ,

wherein the layered material is a layered phyllosilicate.

16. The polyester resin composition according to claim 1 , wherein the polyester resin composition comprises an epoxy-containing compound.

17. The polyester resin composition according to claim 16 ,

wherein the epoxy-containing compound has no ester linkage.

18. The polyester resin composition according to claim 1 ,

wherein the polyether compound-treated layered material is in a powder form.