Polyester resin blends with high-level gas barrier properties

Abstract

Compositions comprising a polyester resin and a polyamide derived from a dicarboxylic acid with 6-22 carbon atoms and from m-xylylene diamine having high-level gas barrier properties, obtained by mixing in the melted state the polyester resin premixed with a dianhydride of a tetracarboxylic acid and the polyamide, operating under conditions such as to render the polymeric components theologically rheologically compatible with each other. The compositions are suitable for preparing containers and biaxially-orientated films.

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.