Polyester resin blends with high-level gas barrier properties

1. A biaxially-oriented article selected from the group consisting of biaxially-oriented films and containers formed by using a material obtained by mixing a melted substance comprising:

a) an aromatic polyester, premixed with a dianhydride of a tetracarboxylic acid in an amount from 0.01 to 3% by weight;

b) a polyamide derived from m-xylylene diamine and from a dicarboxylic acid with 6-22 carbon atoms in an amount from 2 to 50% by weight on the sum of a)+b), wherein the polyamide is dispensed in the polyester in domains with an average size lower than 1 micron.

2. Containers according to claim 1 , in the form of bottles for carbonated beverages.

3. Containers according to claim 1 , obtained by injection blow-molding.

4. Containers according to claim 1 , wherein the aromatic polyester is copolyethylene terephthalate containing up to 25% by weight units or sequences derived from isophthalic acid.

5. Article according to claim 1 , wherein the polyamide is poly m-xylylene adipamide.

6. Article according to claim 1 , wherein the dianhydride of the tetracarboxylic acid is pyromellitic dianhydride.

7. Article according to claim 1 , wherein the starting polyester of the material used to prepare the container has an intrinsic viscosity from 0.3 to 0.8 dl/g.

8. Article according to claim 1 , wherein the material obtained from the melted mixture comprising the polyester, the polyamide and the dianhydride is subjected to solid-state polycondensation for a time and temperature conditions sufficient to increase the intrinsic viscosity of the polyester by at least 0.1 units.

9. Article according to claim 1 , wherein the polyester premixed with the dianhydride is subjected to a solid-state polycondensation treatment thereby the intrinsic viscosity of the initial polyester is increased by 0.1 units.

10. Article according to claim 1 , wherein the melt viscosities of the polyester and the polyamide, determined at the mixing temperature, are in a ratio from 0.2:1 to 4:1.

11. Article according to claim 1 , wherein the mixing of the components is performed in the extruder.

12. Article made of or comprising a material obtained from compositions comprising a polyester resin and a polyamide wherein they have an oxygen permeability of less than 0.065 ml/bottle/day/atm, measured on a 1.5-liter bottle with a thickness of 225 microns obtained by injection blow molding.

13. Films according to claim 5 , obtained by biaxial stretching of films prepared by cast-extrusion.

14. Films according to claim 1 , obtained by blow-molding using the double-bubble method.

15. A polymeric material usable for preparing articles selected from the groups consisting of biaxially-oriented films and containers having high characteristics of resistance to gas CO 2 permeability of less than 7.25 ml/bottle/d/atm, as measured on a 1.5 liter bottle having an average thickness of 225 microns, obtained by mixing a melted material, comprising:

a) an aromatic polyester resin, premixed with a dianhydride of a tetracarboxylic acid, in an amount between 0.01 and 3% by weight;

b) a polyamide derived from m-xylylene diamine and from a dicarboxylic acid with 6-22 carbon atoms wherein the polyamide is dispensed in the polyester in domains with an average size lower than 1 micron.

16. A material according to claim 15 , wherein the polyester resin is copolyethylene terephthalate containing up to 25% by weight of units derived from isophthalic acid.

17. A material according to claim 15 , wherein the polyamide is poly m-xylylene adipamide.

18. A polymeric material according to claim 15 , wherein the dianhydride is pyromellitic dianhydride.

19. A polymeric material according to claim 15 , wherein the material obtained from the melted mixture comprising the components a), b) and c) is subjected to solid-state polycondensation until the intrinsic viscosity of the starting polyester is increased of at least 0.1 units.

20. A polymeric material according to claim 19 , wherein the polyester premixed with the dianhydride is subjected to solid-state polycondensation until the intrinsic viscosity of the initial polyester is increased of at least 0.1 units.

21. A polymeric material according to claim 15 , wherein the polyester and the polyamide have melt viscosities, at the mixing temperature, in a ratio from 0.2:1 to 4:1.

22. Containers whose resistance to oxygen permeability is less than 0.065 ml/bottle/day/atm, measured on a 1.5-liter bottle with a thickness of 225 microns prepared by injection-blow molding obtained from the polymeric material of claim 15 .

23. A polymeric material comprising an aromatic polyester resin and a, poly-m-xylylene adipamide wherein the poly-m-xylylene adipamide is dispersed in a polyester resin matrix in domains with average size from 0.2 to 0.4 micron.

24. A polymeric material according to claim 23 wherein the polyester resin is a copolyethylene terephthalate containing up to 25% by weight of units derived from isophthalic acid and the polyamide is poly-m-xylylene adipamide.

25. Films according to claim 12 obtained by biaxial stretching of films prepared by cast-extrusion.

26. A polymeric material according to claim 23 wherein the polyester resin is a copolyethylene terephthalate containing 1% to 15% by weight units derived from isophthalic acid and wherein the polyamide is poly-m-xylylene adipamide.

27. A polymeric material according to claim 23 which is further comprised of pyromellitic dianhydride.

28. A polymeric material according to claim 26 which is further comprised of pyromellitic dianhydride.

29. A polymeric material according to claim 23 wherein the polymeric material is in the form of a preform.

30. A polymeric material according to claim 24 wherein the polymeric material is in the form of a preform.

31. A polymeric material according to claim 26 wherein the polymeric material is in the form of a preform.

32. A container which is made from the polymeric material specified in claim 23.

33. A container which is made from the polymeric material specified in claim 24.

34. A container which is made from the polymeric material specified in claim 26.

35. A container which is made from the preform specified in claim 29.

36. A container which is made from the preform specified in claim 30.

37. A container which is made from the preform specified in claim 31.

38. A container as specified in claim 32 wherein the container is made by injection-blow molding.

39. A container as specified in claim 33 wherein the container is made by injection-blow molding.

40. A container as specified in claim 34 wherein the container is made by injection-blow molding.

41. A bottle which is made from the polymeric material specified in claim 23.

42. A bottle which is made from the polymeric material specified in claim 24.

43. A bottle which is made from the polymeric material specified in claim 26.

44. A bottle made from the preform specified in claim 29.

45. A bottle made from the preform specified in claim 30.

46. A bottle made from the preform specified in claim 31.

47. A bottle as specified in claim 41 wherein the bottle is made by injection-blow molding.

48. A bottle as specified in claim 42 wherein the bottle is made by injection-blow molding.

49. A bottle as specified in claim 43 wherein the bottle is made by injection-blow molding.

50. A bottle as specified in claim 44 wherein the bottle is made by injection-blow molding.

51. A bottle as specified in claim 45 wherein the bottle is made by injection-blow molding.

52. A bottle as specified in claim 46 wherein the bottle is made by injection-blow molding.

53. A bottle as specified in claim 47 wherein said bottle has a CO 2 permeability of less than 7.25 ml/bottle/d/atm, as measured on a 1.5 liter bottle having an average thickness of 225 microns.

54. A bottle as specified in claim 52 wherein said bottle has a CO 2 permeability of less than 7.25 ml/bottle/d/atm, as measured on a 1.5 liter bottle having an average thickness of 225 microns.