Pouch for packaging flowable materials

• US 5,360,648 A
• Filed: 06/24/1993
• Issued: 11/01/1994
• Est. Priority Date: 06/24/1993
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Falla, Daniel J., Restaino, Michael C.
• Primary Examiner(s): Nold, Charles R.
• Application Number:
  US08/082,136
• Time in Patent Office: 495 Days
• Field of Search: 428/35.7, 428/34.9, 428/35.1, 428/35.2, 428/213, 428/500, 428/515, 428/518, 383/109, 383/113, 525/240, 526/348.5, 426/127, 426/130, 426/106, 220/569, 220/415, 220/DIG. 11, 206/524.3
• US Class Current: 428/35.2
• CPC Class Codes: B32B 2323/04 Polyethylene
• CPC Class Codes: B32B 2323/046 LDPE, i.e. low density polyethylene
• CPC Class Codes: B32B 2439/46 Bags
• 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: B32B 37/153 at least one layer is extruded and immediately laminated while in semi-molten state
• CPC Class Codes: B65D 75/008 Standing pouches, i.e. "Standbeutel"
• CPC Class Codes: Y10T 428/1328 Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/1334 Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31909 Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/3192 Next to vinyl or vinylidene chloride polymer

Abstract

An environmentally friendly polymer film pouch made from a homogeneously branched substantially linear ethylene interpolymer film structure for the packaging of flowable materials such as milk, is disclosed. A pouch made from a multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one seal layer of a homogeneously branched substantially linear polyethylene is also disclosed.

A process for making a pouch for packaging flowable materials using a homogeneously branched substantially linear ethylene interpolymer film structure is also disclosed.

Claims

1. A pouch made from a film structure in tubular form and having transversely heat sealed ends, the film structure having at least one film layer comprising:

(I) from 10 to 100 percent by weight of at least one homogeneously branched substantially linear ethylene/α

-olefin interpolymer characterized as having;

(a) a melt flow ratio, I₁₀ /I₂, ≧

5.63, and

(b) a molecular weight distribution, M_w /M_n, defined by the equation;

M_w /M_n ≦

(I₁₀ /I₂)-4.63; and

(c) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear ethylene/alpha-olefin interpolymer having about the same I₂ and M_w /M_n

(II) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a heterogeneously branched linear ethylene/C₃ -C₁₈ α

-olefin copolymer, a high-pressure low density polyethylene, and an ethylene-vinyl acetate copolymer.

2. The pouch of claim 1 wherein the film layer comprising (I) and (II) is a seal layer said seal layer having a minimum thickness of about 0.1 mil.

3. The pouch of claim 2 wherein the film structure has an outer layer comprising at least one polymer selected from the group consisting of a heterogeneously branched linear ethylene/C₃ -C₁₈ α

-olefin copolymer, a high-pressure low density polyethylene, and an ethylene-vinyl acetate copolymer.

4. The pouch of claim 3 wherein the film structure has a core layer comprising a high-pressure low density polyethylene.

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

-olefin interpolymer is a copolymer of ethylene and a C₃ -C₂₀ α

-olefin.

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

-olefin interpolymer is a copolymer of ethylene and 1-octene.

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

-olefin interpolymer is a terpolymer of ethylene and at least one C₃ -C₂₀ α

-olefin.

8. The pouch of claim 1 wherein the molecular weight distribution, M_w /M_n, of the homogeneously branched substantially linear ethylene/α

-olefin interpolymer of (I) is from about 1.5 to about 2.5.

9. The pouch of claim 1 wherein the melt flow ratio, I₁₀ /I₂, of the homogeneously branched substantially linear ethylene/α

-olefin interpolymer of (I) is at least about 7.

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

-olefin interpolymer of (I) has a melt index, I₂, from about 0.01 grams/10 minutes to about 10 grams/10 minutes, and a density from about 0.85 grams/cm³ to about 0.94 grams/cm³, a molecular weight distribution, M_w /M_n, from about 1.5 to about 2.5, and a melt flow ratio, I₁₀ /I₂, of at least about 7.

11. The pouch of claim 1 wherein the heterogeneously branched linear ethylene/C₃ -C₁₈ -α

-olefin copolymer of (II) has a density greater than about 0.916 g/cm³ and a melt index from about 0.1 to about 10 g/10 minutes.

12. The pouch of claim 1 wherein the high-pressure low density polyethylene of (II) has a density from about 0.916 to about 0.93 g/cm³ and a melt index from about 0.1 to about 10 g/10 minutes.

13. The pouch of claim 1 wherein the ethylene-vinyl acetate copolymer of (II) has a weight ratio of ethylene to vinyl acetate from 2.2:

1 to 24;

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

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

15. The pouch of claim 1 wherein the pouch contains a flowable material.

16. The pouch of claim 15 wherein the flowable material is milk.