Flexible bottles of polyester resin

1. A flexible bottle capable of being filled with a liquid, where said bottle is comprised of an aromatic polyester resin with an intrinsic viscosity of 0.7 to 0.85 dl/g, said bottle being provided with a closable neck for filling/emptying of the liquid, wherein said bottle has no welded seams, wherein said bottle has a capacity of at least 2 liters, wherein the ratio between the capacity in liters and the weight in grams of the bottle, excluding the neck, is from 0.15 to 0.5 for capacities of up to 2 to 5 liters and from 0.2 to 1.5 for capacities greater than 5 liters and less than 40 liters, and wherein the weight of in grams of the bottle, excluding the neck, includes the weight of the sidewall of the bottle.

2. A bottle according to claim 1 , in which the polyester resin is copolyethylene terephthalate in which from 2 to 20 mol % of the units derived from terephthalic acid are replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

3. A bottle according to claim 1 , in which the polyester resin is blended with an aliphatic polyester resin in a quantity less than 40 wt. % relative to the blend.

4. A bottle according to claim 1 , wherein the bottle has a capacity of greater than 10 liters, and wherein the ratio between capacity in liters and weight in grams is between 0.8 and 1.1.

5. A bottle according to claim 1 wherein the distortion characteristics of the bottle are reduced by thermal stabilization of the bottle.

6. A bottle according to claim 1 , obtained by means of free blowing in the absence of a mold of a parison of aromatic polyester resins having rheological properties such that the parison may be blown until the desired capacity relative to weight is obtained.

7. A bottle according to claim 6 , in which the parison is obtained from a copolyethylene terephthalate with an intrinsic viscosity of 0.7 to 0.85 dl/g, in which from 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

8. A bottle according to claim 7 , in which the intrinsic viscosity of the copolyethylene terephthalate is adjusted to values of 0.7-0.85 dl/g by means of solid phase polycondensation of a copolyethylene terephthalate with an intrinsic viscosity of less than 0.7 dl/g, and the copolyethylene terephthalate contains pyromellitic dianhydride and the pyromellitic dianhydride is present at a level less than 0.1 wt. %.

9. A bottle according to claim 1 , in which the parison is blown inside a rigid container, the geometry of which it assumes.

10. A bottle according to claim 9 , in which the container is a paperboard box.

11. A bottle according to claim 10 , in which the parison is obtained from a copolyethylene terephthalate with an intrinsic viscosity of 0.7 to 0.85 dl/g, in which fromo 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

12. A bottle according to claim 11 , in which the intrinsic viscosity of the copolyethylene terephthalate is adjusted to values of 0.7-0.85 dl/g by means of solid phase polycondensation of a copolyethylene terephthalate with an intrinsic viscosity of less than 0.7 dl/g, and the copolyethylene terephthalate contains pyromellitic dianhydride and the pyromellitic dianhydride is present at a level less than 0.1 wt. %.

13. A bottle according to claim 9 , in which the container is a metal container.

14. A bottle according to claim 13 , in which the parison is obtained from a copolyethylene terephthalate with an intrinsic viscosity of 0.7 to 0.85 dl/g, in which from 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

15. A bottle according to claim 14 , in which the intrinsic viscosity of the copolyethylene terephthalate is adjusted to values of 0.7-0.85 dl/g, by means of solid phase polycondensation of a copolyethylene terephthalate with an intrinsic viscosity of less than 0.7 dl/g, and the copolyethylene terephthalate contains pyromellitic dianhydride and the pyromellitic dianhydrie is present at a level less than 0.1 wt. %.

16. A bottle according to claim 9 , in which the parison is obtained from a copolyethylene terephthalate with an intrinisc viscosity of 0.7 to 0.85 dl/g, in which from 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

17. A bottle according to claim 16 , in which the parison is obtained from a copolyethylene terephthalate with an intrinsic viscosity of 0.7-0.85 dl/g, in which from 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

18. A bottle according to claim 1 , which is inserted into a container having sufficient integrity to withstand the mechanical stresses which the bottles are not capable of withstanding.

19. A bottle according to claim 18 , in which the parison is obtained from a copolyethylene terephthalate with an intrinsic viscosity of 0.7 to 0.85 dl/g, in which from 10 to 15 mol % of terephthalic acid units have been replaced by units derived from isophthalic acid and/or naphthalenedicarboxylic acids.

20. A bottle according to claim 19 , in which the intrinsic viscosity of the copolyethylene terephthalate is adjusted to values of 0.7-0.85 dl/g by means of solid phase polycondensation of a copolyethylene terephthalate with an intrinsic viscosity of less than 0.7 dl/g, and the copolyethylene terephthalate contains pyromellitic dianhydride and the pyromellitic dianhydride is present at a level of less than 0.1 wt. %.