Pouches for packaging flowable materials in pouches

• US 5,721,025 A
• Filed: 12/05/1995
• Issued: 02/24/1998
• Est. Priority Date: 12/05/1995
• 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): NOLD, CHARLES R
• Application Number:
  US08/567,608
• Time in Patent Office: 812 Days
• Field of Search: 428/35.2, 428/35.5, 428/192, 428/349, 428/516, 426/127, 426/130, 525/222, 525/240, 156/308.4, 156/145, 156/292
• US Class Current: 428/35.2
• CPC Class Codes: B29C 53/38 by bending sheets or strips at right angles to the longitudinal axis of the article being formed and joining the edges
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2307/41 Opaque
• CPC Class Codes: B32B 2439/70 Food packaging
• 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: B65D 65/20 with provision for excluding light of a particular wavelength
• 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: 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
• 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. The film may be a monolayer or multilayer structure, such as two-layer or a three-layer coextruded film containing at least one layer of a blend of an ultra low density polyethylene and a high pressure low density polyethylene as a seal layer having high melt strength. 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 ultra low density polyethylene being a linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having (a) a density from 0.89 g/c.c. to less than 0.916 g/c.c., (b) a melt index (I₂) of less than 10 g/10 minutes, (c) a melt flow ratio, I₁₀ /I₂, greater than 0.1 (d) a molecular weight distribution, Mw/Mn ratio, of greater than 3 (e) 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 at least one high pressure low density-polyethylene having (a) a density from 0.916 g/cc to 0.93 g/cc, (b) a melt index (I₂) of less than 1 g/10 minutes and (c) a 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 a linear low density polyethylene, a high pressure low density polyethylene, and an ethylene-vinyl acetate copolymer.

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 ultra low density polyethylene has an I₁₀ /I₂ 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-butene.

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

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 alpha-olefin of the film structure is a mixture of at least two α

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

18. 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.

19. 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.

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

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 at least one ultra low density polyethylene being a linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having (a) a density from 0.89 g/cc to less than 0.916 g/cc, (b) a melt index (I₂) of less than 10 g/10 minutes, (c) a melt flow ratio, I₁₀ /I₂ greater than 5 (d) a molecular weight distribution, Mw/Mn ratio, of greater than 3 (e) 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 at least one high pressure low density polyethylene having a density from 0.916 to 0.93 g/cc, a melt index (I₂) 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 a linear low density polyethylene, a high pressure low density polyethylene, and an ethylene-vinyl acetate copolymer;

(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/cc 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/cc 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.

21. A film structure of a polymeric composition for a packaging application 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 ultra low density polyethylene being a linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having (a) a density from 0.89 g/cc to less than 0.916 g/cc, (b) a melt index (I₂) of less than 10 g/10 minutes, (c) a melt flow ratio, I₁₀ /I₂ greater than 5 (d) a molecular weight distribution, Mw/Mn ratio, of greater than about 3 (e) 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 0.93 g/cc, a melt index of less than about 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 a linear low density polyethylene, a high pressure low density polyethylene, and an ethylene-vinyl acetate copolymer.

22. The film of claim 21 wherein the density of the linear ethylene copolymer is from 0.916 to 0.94 g/cm³.

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

24. The film of claim 21 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 25 percent based on the total weight of said composition.

25. The film of claim 21 wherein the melt strength of the polymeric composition is in the range from 5 to 70 cN.

26. 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 ultra low density polyethylene being linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having (a) a density from 0.89 g/cc to less than about 0.916 g/cc, (b) a melt index (I₂) of less than 10 g/10 minutes, (c) a melt flow ratio, I₁₀ /I₂ greater than 5 (d) a molecular weight distribution, Mw/Mn ratio, of greater than 3 (e) 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 0.93 g/cc, a melt index (I₂) 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 a linear low density polyethylene, a high pressure low density polyethylene, and an ethylene-vinyl acetate copolymer.

27. 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 ultra low density polyethylene being linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₈ and having (a) a density from 0.89 g/cc to less than about 0.916 g/cc, (b) a melt index (I₂) of less than 10 g/10 minutes, (c) a melt flow ratio, I₁₀ /I₂ greater than 5 (d) a molecular weight distribution, Mw/Mn ratio, of greater than 3 (e) a peak melting point greater than about 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 about 0.916 to 0.93 g/cc, melt index (I₂) of less than 1 g/10 minutes and melt strength greater than about 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 a linear low density polyethylene, a high pressure low density polyethylene, and an ethylene-vinyl acetate copolymer;

(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 0.094 g/cc and a melt index (I₂) of from 0.1 to 10 g/10 minutes.

28. The process of claim 27 wherein the film structure includes:

(III) at least one layer of a high-pressure polyethylene having a density of from 0.916 to 0.93 g/cc and a melt index (I₂) of from 0.1 to 10 g/10 minutes.