Pouches for packaging flowable materials

• US 6,117,465 A
• Filed: 03/26/1998
• Issued: 09/12/2000
• Est. Priority Date: 09/12/1995
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Falla, Daniel James
• Primary Examiner(s): BHAT, NINA NMN
• Application Number:
  US09/048,769
• Time in Patent Office: 901 Days
• Field of Search: 428/35.2, 428/35.5, 428/192, 428/349, 428/516, 426/127, 426/130, 156/308.4, 156/145, 525/222, 525/240
• US Class Current: 426/127
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2307/41 Opaque
• CPC Class Codes: B32B 2323/046 LDPE, i.e. low density polyethylene
• CPC Class Codes: B32B 2439/02 Open containers
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/08 Copolymers of ethene C08L23/16 takes precedence
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 23/0853 Vinylacetate
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• 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 428/1345 Single layer [continuous layer]
• CPC Class Codes: Y10T 428/24777 Edge feature
• CPC Class Codes: Y10T 428/2826 Synthetic resin or 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 linear ethylene interpolymer and a high pressure low density polyethylene as a seal layer. Also disclosed is a process for making a pouch for packaging flowable materials using a film structure of a blend of a linear ethylene interpolymer and a high pressure low density polyethylene.

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 consisting essentially of:

(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 a 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 less than 10 g/10 minutes, and a molecular weight distribution, Mw/Mn, ratio of greater than 4.0, and a peak melting point greater than 100°

C. as measured by a differential scanning colorimeter, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of a 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, of an ethylene-vinyl acetate copolymer having 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.

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

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

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

10. 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.

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

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

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

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

15. 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.

16. 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.

17. The pouch of claim 1 wherein the melt strength of the polymeric composition is in the range of from 10 to 70 cN.

18. The pouch of claim 1 wherein the thinning in edge region is reduced by less than 25 percent.

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

(I) a layer of polymeric composition consisting essentially of;

(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 a 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 less than 10 g/10 minutes, and a molecular weight distribution, Mw/Mn, ratio of greater than 4.0, and a peak melting point greater than 100°

C. as measured by a differential scanning colorimeter, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of a 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, of an ethylene-vinyl acetate copolymer having 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; and

(II) at least one layer of a 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.

7. The pouch of claim 4 wherein layer (II) is an outer layer, layer (III) is a core layer and layer (I) is a seal layer.

19. A film structure of a polymeric composition for a packaging application consisting essentially of:

(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 a 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 less than 10 g/10 minutes, and a molecular weight distribution, Mw/Mn, ratio of greater than 4.0, and a peak melting point greater than 100°

C. as measured by a differential scanning colorimeter, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of a 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, of an ethylene-vinyl acetate copolymer having 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.

20. The film of claim 19 wherein the density of the linear ethylene copolymer is from 0.916 to 0.940 g/cm³.

21. The film of claim 20 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 85 percent based on the total weight of said composition.

22. The film of claim 20 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 25 percent based on the total weight of said composition.

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

24. 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 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 less than 10 g/10 minutes, and a molecular weight distribution, Mw/Mn, ratio of greater than 4.0, and a peak melting point greater than 100°

C. as measured by a differential scanning calorimeter, 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, of at least one copolymer selected from the group consisting of an ethylene-vinyl acetate copolymer having 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.

25. 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 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 less than 10 g/10 minutes, and a molecular weight distribution, Mw/Mn, ratio of greater than 4.0, and a peak melting point greater than 100°

C. as measured by a differential scanning colorimeter, 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, of at least one copolymer selected from the group consisting of an ethylene-vinyl acetate copolymer having 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;

(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.

26. The process of claim 25 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.