Freezable/microwavable packaging films and venting packages

Abstract

Multilayer freezable/microwaveable films and packages having both low temperature resistance to withstand subzero freezer storage temperatures and high temperature resistance to withstand microwave cooking temperatures. The freezable/microwaveable films and packages include, for example, a film having at least three coextruded layers comprising an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent the core layer opposite the heat sealable layer. Preferably, the films and packages further include an outer protective layer laminated to the outer skin layer. The freezable/microwaveable packages can include a venting system, such as vent slits or a vent valve in the package, or vents in at least one seal of the package, to facilitate microwave heating or cooking of the package contents.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter regarded as the present invention, it is believed that the presently described technology will be more fully understood from the following description of various embodiments taken in conjunction with the accompanying figures, in which:

FIG. 1 is a cross-sectional view of a multilayer film of at least one embodiment of the present technology.

FIG. 2 illustrates one embodiment of a microwaveable pouch formed from a multilayer film of the present technology having two vent slits in the pouch.

FIG. 3 illustrates one embodiment of a microwaveable pouch formed from a multilayer film of the present technology having two vent holes in the seal along one side of the pouch.

FIG. 4 illustrates one manner in which the vent holes in the seal of the pouch of FIG. 3 can be made.

FIG. 5 illustrates one embodiment of a microwaveable pouch formed from a multilayer film of the present technology having one embodiment of a vent valve in the pouch.

FIG. 6 illustrates one embodiment of a microwaveable pouch formed from a multilayer film of the present technology, with an exploded view of one embodiment of a vent valve in the pouch.

FIG. 7 illustrates one embodiment of a microwaveable pouch formed from a multilayer film of the present technology having one embodiment of a vent valve in the pouch.

FIG. 8 illustrates a side view of one embodiment of a vent valve of the present technology.

FIG. 9 illustrates one embodiment of a non-woven patch for use in a vent valve of the present technology.

FIG. 10 illustrates one embodiment of a plastic film patch for use in a vent valve of the present technology.

Claims

1. A multilayer freezable, microwaveable film comprising: (a) a polyolefin film comprising an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the at least one core layer, opposite the heat sealable layer; wherein the inner heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 105° C. and a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 105° C.; andwherein the outer skin layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 120° C.; and(b) at least one outer protective layer bonded to the outer skin layer.

2. The multilayer freezable, microwaveable film of claim 1, wherein the outer skin layer comprises a propylene/ethylene copolymer, a propylene/butene copolymer, a propylene/hexene copolymer, a propylene/octene copolymer, a mixture thereof, or a blend thereof.

3. The multilayer freezable, microwaveable film of claim 3, wherein the outer skin layer comprises at least one propylene/ethylene copolymer comprising from about 1% to about 8% by weight of an ethylene comonomer, and wherein the outer skin layer has a melt flow rate from about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.

4. The multilayer freezable, microwaveable film of claim 1, wherein the heat sealable layer comprises an ethylene comonomer in an amount of about 1% to about 8% by weight of the copolymer.

5. The multilayer freezable, microwaveable film of claim 1, wherein the heat sealable layer comprises a blend of polypropylene/alpha-olefin copolymers.

6. The multilayer freezable, microwaveable film of claim 1, wherein the core layer comprises a homopolymer polypropylene, a high density polyethylene, a blend thereof, or a mixture thereof.

7. The multilayer freezable, microwaveable film of claim 6, wherein the homopolymer polypropylene has a melt flow rate of about 0.5 g/10 min. to about 25 g/10 min. at about 230° C.

8. The multilayer freezable, microwaveable film of claim 1, wherein the outer protective layer is a polyethylene terephthalate film, a nylon film, a biaxially oriented polypropylene film, or a biaxially oriented propylene/ethylene copolymer film.

9. The multilayer freezable, microwaveable film of claim 1, wherein the outer protective layer is bonded to the outer skin layer by an adhesive, by heat bonding, or by ultrasonic welding.

10. The multilayer freezable, microwaveable film of claim 1, wherein the polyolefin film is a coextruded blown film, a coextruded cast film, or a laminated film.

11. The multilayer freezable, microwaveable film of claim 1, wherein the freezable, microwaveable film can be exposed to a temperature of from about 0° C. to about −20° C. without fracturing; and wherein the freezable, microwaveable film can be exposed to a temperature of at least about 105° C. or greater without melting or bursting.

12. A multilayer freezable, microwaveable package comprising: (a) a polyolefin film comprising an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the core layer opposite the heat sealable layer; wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 105° C. and a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 105° C.; andwherein the outer skin layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 120° C.; and(b) an outer protective layer bonded to the outer skin layer;wherein parts (a) and (b) form a multilayer freezable, microwaveable package;wherein the freezable, microwaveable film can be exposed to a temperature of from about 0° C. to about −20° C. without fracturing; andwherein the freezable, microwaveable film can be exposed to a temperature of about 105° C. or greater without melting or bursting.

13. A multilayer freezable, microwaveable package comprising: a polyolefin film comprising a heat sealable layer, and an outer protective layer bonded to the polyolefin film;wherein the heat sealable layer of the polyolefin film is sealed to itself to form the package;wherein the package further comprises at least one vent slit through the package, the at least one vent slit having a length from about 2 millimeters to about 12 millimeters; andwherein the package has a peak internal pressure of at least about 0.3 psi during microwave cooking when the internal temperature is at least about 71° C.

14. The multilayer freezable, microwaveable package of claim 13, wherein the at least one vent slit is from about 5 millimeters to about 10 millimeters in length.

15. The multilayer freezable, microwaveable package of claim 13, further comprising at least one back seal, at least one first end seal, and at least one second end seal; wherein the at least one vent slit is a distance of at least abut I centimeter from the at least one back seal, the at least one first end seal, or the at least one second end seal.

16. The multilayer freezable, microwaveable package of claim 13, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the at least one core layer opposite the heat sealable layer, wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 71° C.; andwherein the outer skin layer comprises at least one polyethylene resin having a melt flow index of about 0.50 g/10 min to about 20 g/10 min. at about 190° C.

17. The multilayer freezable, microwaveable package of claim 13, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the at least one core layer opposite the heat sealable layer; wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 105° C. and a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 105° C.; andwherein the outer skin layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 120° C.

18. A multilayer freezable, microwaveable package comprising: a polyolefin film comprising a heat sealable layer, and an outer protective layer bonded to the polyolefin film;wherein the heat sealable layer of the polyolefin film is sealed to itself to form at least one seal; andwherein the at least one seal comprises at least one vent formed by at least one opening in the at least one seal of the package.

19. The multilayer freezable, microwaveable package of claim 18, wherein the wherein the heat sealable layer of the polyolefin film is sealed to itself to form at least one back seal, at least one first end seal, and at least one second end seal; and wherein the at least one vent is formed by at least one opening in the at least one first end seal or the at least one second end seal.

20. The multilayer freezable, microwaveable package of claim 18, wherein the at last one vent is from about 2 millimeters to about 20 millimeters in length.

21. The multilayer freezable, microwaveable package of claim 18, wherein the at last one vent is from about 5 millimeters to about 10 millimeters in length.

22. The multilayer freezable, microwaveable package of claim 18, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the at least one core layer opposite the heat sealable layer, Wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 71° C.; andwherein the outer skin layer comprises at least one polyethylene resin having a melt flow index of about 0.50 g/10 min to about 20 g/10 min. at about 190° C.

23. The multilayer freezable, microwaveable package of claim 18, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the core layer opposite the heat sealable layer; wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 105° C. and a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 105° C.; andwherein the outer skin layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 120° C.

24. A multilayer freezable, microwaveable package comprising: a polyolefin film comprising a heat sealable layer, and an outer protective layer bonded to the polyolefin film;wherein the heat sealable layer of the polyolefin film is heat sealed to itself to form at least one seal; andwherein the package further comprises a vent valve comprising a vent hole, a nonwoven patch, and a plastic patch.

25. The multilayer freezable, microwaveable package of claim 24, wherein the vent hole is circular and has a diameter from about 2 millimeters to about 20 millimeters.

26. The multilayer freezable, microwaveable package of claim 24, wherein the nonwoven patch is circular and has a diameter from about 3 millimeters to about 50 millimeters.

27. The multilayer freezable, microwaveable package of claim 24, wherein the plastic patch is circular and has a diameter from about 3 millimeters to about 50 millimeters.

28. The multilayer freezable, microwaveable package of claim 24, wherein the nonwoven patch covers the vent hole and is bonded to the package by a continuous bond; and wherein the plastic patch is bonded to the nonwoven patch in at least two bonding locations.

29. The multilayer freezable, microwaveable package of claim 24, wherein the nonwoven patch comprises fibers of a polypropylene, a polyethylene, a polyethylene terephthalate polyester, a nylon, a paper, a blend thereof, or a mixture thereof.

30. The multilayer freezable, microwaveable package of claim 24, wherein the plastic patch comprises a polypropylene, a polyethylene, a polyethylene terephthalate polyester, a nylon, a polystyrene, a polyvinyl chloride, a blend thereof, or a mixture thereof.

31. The multilayer freezable, microwaveable package of claim 24, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the core layer opposite the heat sealable layer, wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 71° C.; andwherein the outer skin layer comprises at least one polyethylene resin having a melt flow index of about 0.50 g/10 min to about 20 g/10 min. at about 190° C.

32. The multilayer freezable, microwaveable package of claim 24, wherein the polyolefin film comprises an inner heat sealable layer, at least one core layer adjacent to the heat sealable layer, and an outer skin layer adjacent to the at least one core layer opposite the heat sealable layer; wherein the heat sealable layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 105° C. and a melt flow rate of about 0.5 g/10 min. to about 45 g/10 min. at about 230° C.;wherein the at least one core layer comprises a polymeric material having a melting point of at least 105° C.; andwherein the outer skin layer comprises at least one polypropylene/alpha-olefin copolymer having a melting point of at least about 120° C.