Polyester Composition And Method For Preparing Articles By Extrusion Blow Molding

• US 20090264545A1
• Filed: 04/17/2009
• Published: 10/22/2009
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: PepsiCo Incorporated
• Original Assignee: PepsiCo Incorporated
• Inventors: Sequeira, Clarence
• Granted Patent: US 8,404,755 B2
• Time in Patent Office: Days
• US Class Current: 521/48
• CPC Class Codes: B29B 17/0042 for shaping parts, e.g. multilayered parts with at least one layer containing regenerated plastic
• CPC Class Codes: B29B 9/06 in the form of filamentary material, e.g. combined with extrusion
• CPC Class Codes: B29B 9/12 characterised by structure or composition
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/285 Feeding the extrusion material to the extruder
• CPC Class Codes: B29C 48/287 Raw material pre-treatment while feeding B29C48/78 takes precedence
• CPC Class Codes: B29C 49/04 Extrusion blow-moulding
• CPC Class Codes: B29D 22/003 Containers for packaging, storing or transporting, e.g. bottles, jars, cans, barrels, tanks
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/0032 Pigments, colouring agents or opacifiyng agents
• CPC Class Codes: B29K 2105/0038 Plasticisers
• CPC Class Codes: B29K 2105/005 Heat sensitisers or absorbers
• CPC Class Codes: B29K 2105/162 Nanoparticles
• CPC Class Codes: B29K 2105/26 Scrap or recycled material
• CPC Class Codes: B65D 1/00 Containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material, by deep-drawing operations performed on sheet material by winding, bending, or folding paper B65D3/00, B65D5/00; specially constructed to be opened by cutting, piercing, or tearing of wall portions B65D17/00; pallets B65D19/00; details of bottles or of jars B65D23/00; bundles of articles held together by packaging elements for convenience of storage or transport, e.g. portable segregating carriers for plural receptacles such as beer cans, pop bottles, B65D71/00
• CPC Class Codes: C08K 5/053 Polyhydroxylic alcohols
• CPC Class Codes: C08K 5/092 Polycarboxylic acids
• CPC Class Codes: C08L 2203/10 used for bottles
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 2666/18 : Polyesters or polycarbonates according to C08L67/00 - C08L69/00; Derivatives thereof
• CPC Class Codes: C08L 67/02 : Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: C08L 67/03 : the dicarboxylic acids and dihydroxy compounds having the carboxyl- and the hydroxy groups directly linked to aromatic rings
• CPC Class Codes: Y02W 30/62 : Plastics recycling; Rubber recycling
• CPC Class Codes: Y10T 428/1397 : Single layer [continuous layer]

Abstract

Polyester compositions described herein have properties which are particularly suitable for extrusion blow molding (EBM). These properties relate primarily to the rate of crystallization and melt strength or melt viscosity. Articles prepared from the polyester compositions exhibit good clarity, aesthetics, and other physical properties. The polyester compositions also exhibit broad molecular weight distribution (MWD), resulting in improved processability and melt strength. The crystallization rate allows for good drying characteristics while also enabling the use of regrind. In addition, the compositions exhibit improved recyclability, such as in existing PET recycling streams. In one aspect, articles are prepared in an extrusion blow molding method by combining a dry first polyester copolymer component, a dry second polyester component, and a chain extender to form a feed material suitable for extrusion blow molding. In another aspect, a single component co-polyester and a chain extender are combined to form a feed material.

Claims

1. A polyester composition suitable for extrusion blow molding comprising a first polyester copolymer which does not show a peak crystallization time of less than about 45 minutes, a second polyester having a peak crystallization time of less than 45 minutes, and from about 0.1 to about 5 wt % of a chain extender, wherein the first polyester copolymer and the second polyester have a weight ratio of from about 10:

90 to about 90;

10.

2. The composition of claim 1 wherein the first polyester copolymer does not show a peak crystallization time of less than about 60 minutes.

3. The composition of claim 1 wherein the second polyester has a peak crystallization time of less than 15 minutes.

4. The composition of claim 1 wherein the first polyester copolymer comprises a lightly branched and/or unbranched polyethylene terephthalate copolymer of 1,4-cyclohexane-dicarboxylic acid and/or 1,4-cyclohexanedimethanol.

5. The composition of claim 1 wherein the first polyester copolymer comprises a lightly branched and/or unbranched polyethylene terephthalate copolymer of isophthalic acid.

6. The composition of claim 1 wherein the second polyester comprises polyethylene terephthalate.

7. The composition of claim 6 wherein the second polyester comprises up to 100 wt % recycled polyethylene terephthalate.

8. The composition of claim 1 wherein the chain extender is selected from the group consisting of trimellitic anhydride, pyromellitic dianhydride, trimellitic acid, haloformyl derivatives thereof, and combinations thereof.

9. The composition of claim 8 wherein the amount of chain extender ranges from about 0.1 to about 0.5 wt %.

10. The composition of claim 1 further comprising a branching agent selected from the group consisting of pentaerythritol, trimethylolpropane, and combinations thereof.

11. The composition of claim 10 wherein the amount of branching agent ranges from about 0.01 to about 1 wt %.

12. The composition of claim 11 wherein the amount of branching agent ranges from about 0.01 to about 0.1 wt %.

13. A process of extrusion blow molding an article comprising:

combining a dry first polyester copolymer component, a dry second polyester component, and a chain extender to form a feed material suitable for extrusion blow molding; and

feeding the feed material to an extrusion blow molding machine to form an extruded article.

14. The process of claim 13 further comprising combining regrind material with the feed material.

15. The process of claim 14 wherein the regrind material is combined in an amount up to about 90 wt % based on the total weight of the feed material.

16. The process of claim 15 wherein the regrind material is combined in an amount up to about 50 wt % based on the total weight of the feed material.

17. The process of claim 14 wherein the regrind material comprises excess material recovered from the process of extrusion blow molding the article.

18. The process of claim 13 wherein the first polyester copolymer comprises an unbranched or lightly branched polyethylene terephthalate copolymer of 1,4-cyclohexane-dicarboxylic acid, 1,4-cyclohexanedimethanol, isophthalic acid, or combinations thereof.

19. The process of claim 13 wherein the second polyester comprises polyethylene terephthalate.

20. The process of claim 19 wherein the second polyester comprises up to 100 wt % recycled polyethylene terephthalate.

21. The process of claim 13 wherein the chain extender is selected from the group consisting of trimellitic anhydride, pyromellitic dianhydride, trimellitic acid, or haloformyl derivatives thereof.

22. The process of claim 13 further comprising adding a branching agent to the feed material.

23. The process of claim 22 wherein the branching agent is selected from the group consisting of pentaerythritol, trimethylolpropane, and combinations thereof.

24. The process of claim 13 wherein the feed material suitable for extrusion blow molding has a peak crystallization time of less than 60 minutes and at least 8% crystallinity.

25. The process of claim 13 wherein the feed material is produced by combining the dry first polyester copolymer component and a dry second polyester component in an extruder.

26. The process of claim 25 wherein the feed material suitable for extrusion blow molding has a moisture content of less than about 100 ppm.

27. The process of claim 25 wherein the extruder is a twin-screw extruder.

28. The process of claim 27 wherein the extruder has two co-rotating screws and three sets of kneading blocks.

29. The process of claim 28 wherein the extruder has an L/D ratio of at least 20:

1.

30. The process of claim 13 wherein the feed material suitable for extrusion blow molding has a zero shear viscosity of at least 4,000 Pa·

s at a temperature of at least 490°

F.

31. The process of claim 30 wherein the zero shear viscosity is at least 10,000 Pa·

s at a temperature of at least 490°

F.

32. The process of claim 31 wherein the zero shear viscosity is at least 20,000 Pa·

s at a temperature of at least 490°

F.

33. An article formed by the process of claim 13.

34. The article of claim 33 wherein the article has less than 12% haze at an article wall thickness of 30 mils.

35. The article of claim 34 wherein the article may be combined in a PET recycling stream in an amount of at least 10 wt % of the recycling stream and dried at a temperature of 160°

C. in a desiccant dryer for a time of four hours without sticking or bridging.

36. The process of claim 13 wherein the first polyester copolymer component and second polyester component are combined to form a first combination, and a chain extender is added to the first combination to form the feed material suitable for extrusion blow molding.

37. The process of claim 36 wherein a branching agent is added to the first combination to form the feed material suitable for extrusion blow molding.

38. A process of extrusion blow molding an article comprising:

combining a single component co-polyester and a chain extender to form a feed material suitable for extrusion blow molding; and

feeding the feed material to an extrusion blow molding machine to form an extruded article.

39. The process of claim 38 further comprising combining regrind material with the feed material.

40. The process of claim 39 wherein the regrind material is combined in an amount up to about 90 wt % based on the total weight of the feed material.

41. The process of claim 40 wherein the regrind material is combined in an amount up to about 50 wt % based on the total weight of the feed material.

42. The process of claim 39 wherein the regrind material comprises excess material recovered from the process of extrusion blow molding the article.

43. The process of claim 38 wherein the co-polyester comprises an unbranched or lightly branched polyethylene terephthalate copolymer of 1,4-cyclohexane-dicarboxylic acid, 1,4-cyclohexanedimethanol, isophthalic acid, or combinations thereof.

44. The process of claim 38 wherein the chain extender is selected from the group consisting of trimellitic anhydride, pyromellitic dianhydride, trimellitic acid, haloformyl derivatives thereof, and combinations thereof.

45. The process of claim 38 further comprising adding a branching agent to the feed material.

46. The process of claim 45 wherein the branching agent is selected from the group consisting of pentaerythritol, trimethylolpropane, and combinations thereof.

47. The process of claim 38 wherein the feed material suitable for extrusion blow molding has a peak crystallization time of less than 60 minutes and at least 8% crystallinity.

48. The process of claim 38 wherein the feed material suitable for extrusion blow molding has a moisture content of less than about 100 ppm.

49. The process of claim 38 wherein the co-polyester and chain extender are combined in a twin-screw extruder.

50. The process of claim 49 wherein the extruder has two co-rotating screws and three sets of kneading blocks.

51. The process of claim 50 wherein the extruder has an L/D ratio of at least 20:

1.

52. An article formed by the process of claim 38.

53. The article of claim 52 wherein the article has less than 12% haze at an article wall thickness of 30 mils.

54. The article of claim 53 wherein the article may be combined in a PET recycling stream in an amount of at least 10 wt % of the recycling stream and dried at a temperature of 160°

C. in a desiccant dryer for a time of four hours without sticking or bridging.

55. A process of recycling a polyester extrusion blow molded container in a PET recycling stream comprising:

granulating a polyester extrusion blow molded container to form a recycle feed material of particles or flake;

washing the recycle feed material;

drying the recycle feed material; and

further processing the recycle feed material into a form suitable for preparing finished articles.

56. The process of claim 55 wherein the polyester extrusion blow molded container comprises a first polyester copolymer which does not show a peak crystallization time of less than about 45 minutes, a second polyester having a peak crystallization time of less than 45 minutes, and from about 0.1 to about 5 wt % of a chain extender, wherein the first polyester copolymer and the second polyester have a weight ratio of from about 10:

90 to about 90;

10.

57. The process of claim 56 wherein the first polyester copolymer does not show a peak crystallization time of less than 60 minutes.

58. The process of claim 56 wherein the second polyester has a peak crystallization time of less than 15 minutes.

59. The process of claim 56 wherein the first polyester copolymer comprises an unbranched and/or lightly branched polyethylene terephthalate copolymer of 1,4-cyclohexane-dicarboxylic acid and/or 1,4-cyclohexanedimethanol.

60. The process of claim 56 wherein the first polyester copolymer comprises an unbranched and/or lightly branched polyethylene terephthalate copolymer of isophthalic acid.

61. The process of claim 56 wherein the second polyester comprises polyethylene terephthalate.

62. The process of claim 61 wherein the second polyester comprises up to 100 wt % recycled polyethylene terephthalate.

63. The process of claim 56 wherein the amount of chain extender is from about 0.1 to about 0.5 wt %, wherein the chain extender is selected from the group consisting of trimellitic anhydride, pyromellitic dianhydride, trimellitic acid, haloformyl derivatives thereof, and combinations thereof.

64. The process of claim 56 wherein the polyester composition further comprises from about 0.01 to about 1 wt % of a branching agent selected from the group consisting of pentaerythritol, trimethylolpropane, and combinations thereof.

65. The process of claim 55 wherein the polyester extrusion blow molded container comprises a single component co-polyester having a peak crystallization time of less than 15 minutes.