Retortable self-heating food container with air access structure
A flexible, self-heating food container capable of withstanding high temperatures is provided. The container comprises a two-layer laminate structure having an air access flap that can be lifted by the consumer to allow air to enter the part of the container where an exothermic reaction takes place.
1. A package having a first compartment, the package comprising:
a flexible laminate film comprising a bottom layer bonded to a top layer with a permanent adhesive, the bottom layer and the top layer being substantially coextensive;
the bottom layer comprising a substrate and a continuous resinous frangible skin layer, wherein the frangible skin layer is disposed between the substrate and the permanent adhesive;
the top layer being precision scored to form an overcut which defines a periphery of a flap;
the substrate being precision scored to form one or more undercuts, each undercut defining a die cut section; wherein
the frangible skin layer is in direct contact with the permanent adhesive and is located on an outer facing surface of the substrate between the substrate and the permanent adhesive and within the flap periphery such that the frangible skin layer connects the die cut sections of the substrate to the permanent adhesive; and
wherein lifting the flap from the bottom layer removes the die cut sections from the bottom layer to create air holes in the bottom layer through which air can pass to the first compartment.
2. The package of claim 1 wherein:
the top layer is an air and oxygen barrier.
3. The package of claim 2 wherein:
the first compartment holds a chemical reagent that causes an exothermic reaction when exposed to air, the package further comprising a second compartment for holding food.
4. The package of claim 3 wherein:
the flap is attached to the top layer along a hinge line.
5. The package of claim 4 wherein:
the undercuts extend through the frangible skin layer but not the permanent adhesive.
6. The package of claim 5 wherein:
the frangible skin layer is a coextruded skin and is bonded to the permanent adhesive during a lamination process.
7. The package of claim 1 wherein:
the laminate film defines a plane; and
the frangible skin layer comprises a resinous material and a contaminant that weakens the resinous material a direction orthogonal to the plane of the laminate film.
8. The package of claim 1 wherein:
the top layer comprises a barrier layer and an ink layer applied to an inner facing surface of the barrier layer.
9. The package of claim 1 wherein:
the frangible skin layer does not significantly degrade upon exposure to retort temperatures.
10. The package of claim 1 wherein:
the frangible skin layer does not significantly degrade upon exposure to 240-250 degree F. temperatures for several minutes.
11. The package of claim 1 wherein:
the frangible skin layer splits apart in areas that do not connect the die cut sections of the substrate to the permanent adhesive when the flap is lifted from the bottom layer, leaving some of the frangible skin layer affixed to both the flap and the bottom layer; and
the frangible skin layer does not split apart in areas connecting the die cut sections of the substrate to the permanent adhesive when the flap is lifted such that the die cut sections are removed from the substrate to create air holes in the substrate.
12. The package of claim 1 wherein:
the overcut forms a pattern in substantial registration with the frangible skin layer.
13. The package of claim 12 wherein:
the overcut terminates in opposing ends which form the ends of a hinge line along which the flap is permanently affixed to the top layer.
14. The package of claim 12 wherein:
the overcut forms a closed two-dimensional shape so that the flap is completely removable from the package.