Pouch for packaging flowable materials

• US 5,288,531 A
• Filed: 08/09/1991
• Issued: 02/22/1994
• Est. Priority Date: 08/09/1991
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Ross, Allen W., Elliott, Robert S., Falla, Daniel J.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): DYE, RENA
• Application Number:
  US07/742,800
• Time in Patent Office: 928 Days
• Field of Search: 428/35.2, 428/35.4, 428/35.5, 428/192, 428/516, 428/518, 428/349, 426/130, 426/127, 525/240, 525/222
• US Class Current: 428/35.2
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2439/00 Containers; Receptacles
• 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 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: C09J 123/0815 Copolymers of ethene with aliphatic 1-olefins
• 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, including, for example, a pouch made from a multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of ultra low density linear polyethylene, as a seal layer.

Claims

1. A pouch containing a flowable material, said pouch being made from a film in tubular form and having transversely heat sealed ends, said film being made from a material comprising a film structure comprising (a) from 10 to 100 percent by weight of at least one polymeric seal layer of an ultra low density linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₀ and having (1) a density of from about 0.89 g/cm³ to less than 0.915 g/cm³, (2) a melt index of less than 10.0 g/10 minutes and (3) (i) a hot tack or heat seal initiation temperature of less than 100°

C. at a force of at least 1 N/inch (39.4 N/m) or (ii) a hot tack strength of at least 1 N/inch (39.4 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.2 seconds using the DTC Hot Tack Strength Method or a heat seal strength of at least 1 lb_f /inch (175 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.25 seconds using the DTC Heat Seal Strength Method; and

(b) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C₃ -C₁₈ -alpha-olefin having a density of greater than 0.916 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes, a high-pressure low density 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 and 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.

2. The pouch of claim 1 wherein the density of the polymeric seal layer is from about 0.89 g/cm³ to about 0.912 g/cm³.

3. The pouch of claim 1 wherein the pouch holds from about 5 mL to about 5000 mL.

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

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

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

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

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

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

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

(I) (a) from 10 to 100 percent by weight of at least one polymeric seal layer of an ultra low density linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₀ and having (1) a density of from about 0.89 g/cm³ to less than 0.915 g/cm³, (2) a melt index of less than 10.0 g/10 minutes and (3) (i) a hot tack or heat seal initiation temperature of less than 100°

C. at a force of at least 1 N/inch (39.4 N/m) or (ii) a hot tack strength of at least 1 N/inch (39.4 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.2 seconds using the DTC Hot Tack Strength Method or a heat seal strength of at least 1 lb_f /inch (175 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.25 seconds using the DTC Heat Seal Strength Method; and

(b) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C₃ -C₁₈ -alpha-olefin having a density of greater than 0.916 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes, a high-pressure low density 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 and 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 low density ethylene-C₃ -C₁₈ -alpha-olefin copolymer having a density of from about 0.916 to about 0.935 and a melt index of from about 0.1 to about 10 g/10 minutes.

11. The pouch of claim 10 wherein the density of the polymeric seal layer is from about 0.89 g/cm³ to about 0.912 g/cm³.

12. The pouch of claim 10 including (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.

13. The pouch of claim 10 wherein the linear polymer of ethylene has a melt index from less than about 5.0 g/10 minutes.

14. The pouch of claim 10 wherein layer (I) is a seal layer.

15. The pouch of claim 10 wherein layer (II) is an outer layer and layer (I) is a seal layer.

16. The pouch of claim 12 wherein layer (II) is an outer layer, layer (III) is a core layer and layer (I) is a seal layer.

17. A film structure for a pouch container comprising (a) from 10 to 100 percent by weight of at least one polymeric seal layer of an ultra low density linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C₃ -C₁₀ and having (1) a density of from about 0.89 g/cm³ to less than 0.915 g/cm³, (2) a melt index of less than 10.0 g/10 minutes and (3) (i) a hot tack or heat seal initiation temperature of less than 100°

C. at a force of at least 1 N/inch (39.4 N/m) or (ii) a hot tack strength of at least 1 N/inch (39.4 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.2 seconds using the DTC Hot Tack Strength Method or a heat seal strength of at least 1 lb_f /inch (175 N/m) at a seal bar temperature of about 110°

C. and at a time of less than 0.25 seconds using the DTC Heat Seal Strength Method; and

(b) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C₃ -C₁₈ -alpha-olefin having a density of greater than 0.916 g/cm³ and a melt index of from 0.1 to 10 g/10 minutes, a high-pressure low density 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 and 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.

18. The film of claim 17 wherein the density of the polymeric seal layer is from about 0.89 g/cm³ to about 0.912 g/cm³.