Multilayer Thermoformable Materials and Sanitary Food Containers Made Therefrom

Abstract

A multilayer stack of polymeric sheets can be used in thermoforming processes to make objects wherein each sheet has substantially the same shape. The stack includes at least one sheet of a thermoformable polymer, and can include many such sheets. A barrier layer is interposed between at least an overlapping portion at least two of the polymeric sheets in order to prevent fusion of the sheets in the overlapping portion during the thermoforming process. The barrier layer can include an adhesive that adheres the sheets in the overlapping portion. In formed articles including such an adhesive, the sheets can be manually peeled from one another if a suitable adhesive is selected. The stack (and object formed using the stack) can include polymeric sheets that are not thermoformable, but are adhered to the surface of a thermoformable sheet. The sheets and objects can include multiple separable and/or peelable sheets. The stack can be used, for example, to make peelable, re-usable food service trays. In such trays, a rigid base has multiple peelable sheets adhered to at least one surface thereof, the sheets being peelable from the surface to reveal a sanitary surface amenable to food contact.

Description

BACKGROUND OF THE DISCLOSURE[0001]This disclosure relates generally to multiple-polymeric-layer thermoformable materials and articles formed from such materials. In one aspect, the present disclosure relates generally to containers for hygienically containing food, including containers having multiple peelable layers on a surface which contacts the food, such that the same container can be used multiple times to hygienically contain food without the need to sanitize the food-contacting surface between uses.[0002]The disclosure also relates to other containers having peelable surface layers, such as paint trays.[0003]Paint Trays[0004]Paint is commonly applied to walls and other surfaces with a paint roller comprised of a roll of napped textile material or other paint absorbent substrate carried on a handle, and a metal or plastic paint-holding tray into which the roller is placed to load the roll with paint. While useful in quickly applying a uniform paint coating to large surfaces, ...

AI Technical Summary

Benefits of technology

[0019]In one aspect, the subject matter described herein relates to a peelable, multi-use food service container. The container includes a relatively rigid sheet of a thermoformable polymer and at least one, and preferably a plurality of, second sheets of a polymer, each second sheet having a sanitary face and an adhesion face. A first surface of the rigid sheet has a conformation adapted for holding, supporting, or containing a food service item. Each of the second sheets overlaps the rigid sheet at the first surface and conforms to the shape of the first surface. Interposed between the rigid sheet and the adjacent second sheet is a first barrier composition that adheres (e.g., peelably) the rigid sheet and the adhesion face of the adjacent second sheet. A second barrier composition (identical to or different from the first) is interposed between the adhesion and sanitary faces of adjacent second sheets. The second barrier composition peelably adheres the second sheets to one another. The container thus has one or a plurality of hygienic second sheets peelably adhered to a surface adapted for holding, supporting, or containing a food service item. In one embodiment, the second barrier composition is identical between all second sheets. In another embodiment, a second sheet more distal from the rigid sheet is more easily peeled from the second sheet underlying it than is a second sheet more proximal to the rigid sheet. The container can have a protective coat layer applied atop the uppermost second sheet to prevent contamination of and physical damage to the second sheet(s), such as might occur during manufacture, storage, shipping, or installation of the container.

Problems solved by technology

While useful in quickly applying a uniform paint coating to large surfaces, a major disadvantage of the use of this system is the required messy and time consuming chore of cleaning the roller and tray after use.

While effective in eliminating the need to clean the paint tray, these preformed liners are sufficiently expensive that many users attempt to clean and reuse the liners.

Their thickness adds significantly to environmental waste upon disposal and require significant amounts of energy to produce.

While using less material than preformed tray liners, these sheets are awkward and time consuming to individually hand press into place and do not provide a functional liner that exactly conforms to the tray interior, especially in the corners of the tray.

Regardless of whether reusable or disposable food storage containers are employed, use of the containers typically involves generation of significant quantities of waste.

Disposable containers both preclude cost savings that are realized with re-usable containers (since a new container must be used each time) and generate solid waste which must be disposed of properly.

Although reusable containers avoid the economic waste of single use containers, they require sanitation procedures that are costly, time consuming, and generate significant quantities of (usually liquid) waste materials.

Such liners can be difficult to install and to remove in a sanitary fashion.

Also, they are susceptible to bypass if food products from the interior of the liner are spilled or migrate beneath the liner.

When such liners are not adapted specifically to the food service container, problems of fitting and use arise from the unmatched dimensions of the liners and containers.

For example, non-fitted liners can fold or crease to create pockets in which food products can accumulate or be hidden, leading to spoilage or bacterial growth that can contaminate food products in the remainder of the container.

Fitted liners have the drawback that they fit only a specific container, but not others.

Inserted liners also have the drawback that they tend to move or slide around in the food service container when foodstuffs are manipulated therein.

Furthermore, known liners also have disadvantages stemming from the fact that they are formed (like plastic bags) by welding, adhering, or otherwise sealing plastic sheets along a seam.

The seams can often leak or tear, defeating the purpose of the liner.

Insertable liners also tend to be relatively unsightly and expensive.

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