Pouches for packaging flowable materials

• US 5,879,768 A
• Filed: 10/06/1995
• Issued: 03/09/1999
• Est. Priority Date: 10/06/1995
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Saavedra, Jose V., Falla, Daniel James
• Primary Examiner(s): PEZZUTO, HELEN LEE
• Application Number:
  US08/540,107
• Time in Patent Office: 1,250 Days
• Field of Search: 428/35.7, 428/516
• US Class Current: 428/35.7
• CPC Class Codes: B32B 2307/41 Opaque
• CPC Class Codes: B32B 2307/71 Resistive to light or to UV
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B65D 2565/385 especially suited for or with means facilitating recycling
• CPC Class Codes: B65D 75/008 Standing pouches, i.e. "Standbeutel"
• CPC Class Codes: B65D 75/48 containing liquids, semiliquids, or pastes, e.g. cushion-shaped packages
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 23/04 Homopolymers or copolymers of ethene
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 23/0853 Vinylacetate
• CPC Class Codes: C08L 2314/06 Metallocene or single site catalysts
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: Y10T 428/1334 Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer

Abstract

An environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of a substantially linear ethylene polymer or a homogeneously branched ethylene polymer and a high pressure low density polyethylene as a seal layer. Also disclosed is a process for making the pouch for packaging flowable materials using a film structure described hereinabove.

Claims

1. A pouch containing a flowable material, said pouch being made from a film structure with at least one seal layer of a polymeric composition comprising:

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/α

-olefin interpolymer characterized as having;

(a) a melt flow ratio, I₁₀ /I₂ ≧

5.63;

(b) a molecular weight distribution, Mw/Mn, defined by the equation;

Mw/Mn≦

(I₁₀ /I₂)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm³, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.

3. The pouch of claim 1 wherein said film structure is in a tubular form and said pouch has transversely heat sealed ends.

7. The pouch of claim 3 wherein layer (II) is an outer layer, layer (III) is a core layer and layer (I) is a seal layer.

8. The pouch of claim 1 wherein the homogeneously branched substantially linear ethylene/a-olefin interpolymer is further characterized as having a single melting point as determined by differential scanning calorimetry between -30°

C. and 150°

C.

9. The pouch of claim 1 wherein the homogeneously branched substantially linear ethylene/α

-olefin interpolymer is further characterized as having a critical shear stress at the onset of gross melt fracture of greater than about 4×

10⁶ degrees/cm².

10. The pouch of claim 1 wherein the pouch holds from about 5 mL to about 10,000 mL.

11. The pouch of claim 1 wherein the flowable material is milk.

12. The pouch of claim 1 wherein the copolymer of ethylene has an indicator of molecular weight distribution (I₁₀ /I₂) of from 0.1 to 20.

13. The pouch of claim 1 wherein the film structure contains a slip agent, antiblock agent and, optionally, a processing aid.

14. The pouch of claim 1 wherein the film structure contains a pigment to render the film structure opaque.

15. The pouch of claim 1 wherein the film structure contains an ultraviolet light absorbing additive.

16. The pouch of claim 1 wherein the alpha-olefin of the film structure is 1-octene.

17. The pouch of claim 1 wherein the melt strength of the high pressure low density polyethylene is in the range of from 10 to 40 cN.

18. The pouch of claim 1 wherein the melt strength of the high pressure low density polyethylene is in the range of from 13 to 25 cN.

19. The pouch of claim 1 wherein the melt strength of the polymeric composition is in the range of from 5 to 70 cN.

47. The pouch of claim 1 wherein said ethylene-vinyl acetate copolymer has a weight ratio of ethylene to vinyl acetate from 2.2:

1 to 24;

1 and a melt index of from 0.2 to 10 g/10 minutes.

2. A pouch containing a flowable material, said pouch being made from a multilayer film structure comprising:

(I) a layer of polymeric composition comprising;

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of linear ethylene of at least one homogeneously branched substantially linear ethylene/α

-olefin interpolymer characterized as having;

(a) a melt flow ratio, I₁₀ /I₂ ≧

5.63;

(b) a molecular weight distribution, Mw/Mn, defined by the equation;

Mw/Mn≦

(I₁₀ /I₂)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.

(II) at least one layer of linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having a density from 0.916 to 0.940 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes.

4. The pouch of claim 2 having (III) a layer of a high-pressure polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes.

5. The pouch of claim 2 wherein layer (I) is a seal layer.

6. The pouch of claim 2 wherein layer (II) is an outer layer and layer (I) is a seal layer.

20. A pouch containing a flowable material, said pouch being made from a film structure with at least one seal layer of a polymeric composition comprising:

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm³, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α

-olefin interpolymer.

22. The pouch of claim 20 wherein said film structure is in a tubular form and said pouch has transversely heat sealed ends.

26. The pouch of claim 22 wherein layer (II) is an outer layer, layer (III) is a core layer and layer (I) is a seal layer.

28. The pouch of claim 20 wherein the pouch holds from about 5 mL to about 10,000 mL.

29. The pouch of claim 20 wherein the flowable material is milk.

30. The pouch of claim 20 wherein the copolymer of ethylene has an indicator of molecular weight distribution (I₁₀ /I₂) of from 0.1 to 20.

31. The pouch of claim 20 wherein the film structure contains a slip agent, antiblock agent and, optionally, a processing aid.

32. The pouch of claim 20 wherein the film structure contains a pigment to render the film structure opaque.

33. The pouch of claim 20 wherein the film structure contains an ultraviolet light absorbing additive.

34. The pouch of claim 20 wherein the alpha-olefin of the film structure is 1-octene.

35. The pouch of claim 20 wherein the alpha-olefin of the film structure is 1-butene.

36. The pouch of claim 20 wherein the alpha-olefin of the film structure is 1-hexene.

37. The pouch of claim 20 wherein the alpha-olefin of the film structure is a mixture of at least two all α

-olefins selected from the group consisting of 1-butene, 1-hexene, and 1-octene.

38. The pouch of claim 20 wherein the melt strength of the high pressure low density polyethylene is in the range of from 10 to 40 cN.

39. The pouch of claim 20 wherein the melt strength of the high pressure low density polyethylene is in the range of from 13 to 25 cN.

40. The pouch of claim 20 wherein the melt strength of the polymeric composition is in the range of from 10 to 70 cN.

49. The pouch of claim 20 wherein said ethylene-vinyl acetate copolymer has a weight ratio of ethylene to vinyl acetate from 2.2:

1 to 24;

1 and a melt index of from 0.2 to 10 g/10 minutes.

21. A pouch containing a flowable material, said pouch being made from a multilayer film structure comprising:

(I) a layer of polymeric composition comprising;

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, homogeneously branched linear ethylene polymer and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α

-olefin interpolymer.

(II) at least one layer of linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having a density from 0.916 to 0.940 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes.

23. The pouch of claim 21 having (III) a layer of a high-pressure polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes.

24. The pouch of claim 21 wherein layer (I) is a seal layer.

25. The pouch of claim 21 wherein layer (II) is an outer layer and layer (I) is a seal layer.

27. The pouch of claim 21 wherein the homogeneously branched substantially linear ethylene/α

-olefin interpolymer is further characterized as having a single melting point as determined by differential scanning calorimetry between -30°

C. and 150°

C.

41. A process for preparing a pouch containing a flowable material comprising forming a film structure by either blown tube extrusion or cast extrusion, forming the film structure into a tubular member and transversely heat-sealing opposite ends of the tubular member, said tubular member comprising a film structure for a pouch container with at least one seal layer of a polymeric composition comprising:

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/∝

-olefin interpolymer characterized as having;

(a) a melt flow ratio, I₁₀ /I₂ ≧

5.63;

(b) a molecular weight distribution, Mw/Mn, defined by the equation;

Mw/Mn≦

(I₁₀ /I₂)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.

48. The process of claim 41 wherein the ethylene-vinyl acetate copolymer in the film structure has a weight ratio of ethylene to vinyl acetate from 2.2:

1 to 24;

1 and a melt index of from 0.2 to 10 g/10 minutes.

42. A process for preparing a pouch containing a flowable material comprising forming a film structure by either blown tube extrusion or cast extrusion, forming the film structure into a tubular member and transversely heat-sealing opposite ends of the tubular member, said tubular member comprising:

(I) a layer of polymeric composition comprising;

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/α

-olefin interpolymer characterized as having;

(a) a melt flow ratio, I₁₀ /I₂ ≧

5.63;

(b) a molecular weight distribution, Mw/Mn, defined by the equation;

Mw/Mn≦

(I₁₀ /I₂)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.

(II) at least one layer of linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having a density from 0.916 to 0.0940 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes.

43. The process of claim 42 wherein the film structure includes:

(III) at least one layer of a high-pressure polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes.

44. A process for preparing a pouch containing a flowable material comprising forming a film structure by either blown tube extrusion or cast extrusion, forming the film structure into a tubular member and transversely heat-sealing opposite ends of the tubular member, said tubular member comprising a film structure for a pouch container with at least one seal layer of a polymeric composition comprising:

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm³, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α

-olefin interpolymer.

46. The process of claim 44 wherein the film structure includes:

(III) at least one layer of a high-pressure polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes.

50. The process of claim 44 wherein the ethylene-vinyl acetate copolymer in the film structure has a weight ratio of ethylene to vinyl acetate from 2.2:

1 to 24;

1 and a melt index of from 0.2 to 10 g/10 minutes.

45. A process for preparing a pouch containing a flowable material comprising forming a film structure by either blown tube extrusion or cast extrusion, forming the film structure into a tubular member and transversely heat-sealing opposite ends of the tubular member, said tubular member comprising:

(I) a layer of polymeric composition comprising;

(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm³, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190°

C.; and

(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α

-olefin interpolymer.

(II) at least one layer of linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having a density from 0.916 to 0.0940 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes.