JPS6340293A - Microwave cooking tray for controlled energy distribution - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a microwave oven or microwaveable food tray, into which food is placed or placed and heated by the microwave oven. This is how it is.

PRIOR ART Such trays are placed in a horizontal position in a microwave oven, and the trays often include a layer of metal foil, such as aluminum foil, with holes drilled in them to cover multiple predetermined areas of the tray. It controls the amount of microwave energy that passes through, and these areas correspond to the food or predetermined portions of the food on the tray that are to be heated. The holes or openings in the metal foil are typically 2,45
Zero megahertz microwave energy is passed through the holes, while the non-open portions of the metal foil serve to at least partially shield the energy from portions of the food. The metal foil of such metal-shielded or energy-directing trays used in microwave ovens is typically placed on top of the tray and constitutes the top layer of a multilayer tray stack. It has been recognized in the prior art that many aperture arrangements in the metal foil are suitable for the above-described shielding or energy-directing purposes; The outer circumferential edge of the metal foil substantially coincides with the outer circumferential edge of a layer other than the metal foil among the plurality of layers constituting the oven tray together with the metal foil.

[Problem to be Solved by the Invention] It is known that arcing sometimes occurs between the vertically extending walls of microwave ovens and the perimeter of the tray;
This is because the metal foil is close to the vertical wall of the microwave oven. It is also known that arcing can occur between adjacent trays within an oven.

[Means and effects for solving the problems] According to the implementation of the present invention, there is a tray structure in which energy is controlled by metal foil, and the outer peripheral edge of the metal foil is the outer peripheral edge of the other plural layers constituting the tray. Arcing is prevented by the tray structure being spaced apart from each other. This structure also prevents arcing between the vertical wall of the microwave oven and the outer peripheral edge of the metal foil by providing a space between the metal foil and the tray wall. moreover,
The trays of the present invention are provided with downwardly bent ends to prevent arcing between adjacent trays.

[Example] Fig. 1 is a cross-sectional view of an intermediate laminated product, that is, the components of the tray, for forming the tray of the present invention, Fig. 2 is a top view of Fig. 1, and Fig. 3 is a cross-sectional view of the components of the tray of the present invention. FIG. 4 is a top view of FIG. 3, and FIG. 5 is a cross-sectional view of a tray of the present invention.

In FIG. 1, 10 indicates a two-layer intermediate laminate product or tray component constituted by a paperboard layer and a thermoplastic coating. This thermoplastic coating is applied to the inside or top surface of the intermediate product shown in FIG. 12 indicates the bottom of the paperboard and 14 indicates the raised central portion. 16 indicates the sloped side of the paperboard and 18 indicates a horizontally extending flange with a downwardly bent portion 20. 22 indicates a thermoplastic coating, typically polyethylene terephthalate [P, E,
T,] may be used.

Next, reference is made to FIG. The figure illustrates another two-layer intermediate product or tray component, which is formed from an upper layer of aluminum foil and a lower layer of paperboard. 30 indicates the entire aluminum foil-containing intermediate product shown in FIG. This intermediate product has a flat bottom portion 32 with a central raised bottom portion 34 and sloped side walls 36 and a horizontally extending peripheral flange 40. 42 indicates a paperboard layer. The shapes of the two intermediate products shown in FIGS. 1 and 3 are complementary and the intermediate product or stamping 30 can be placed on the lower surface of the intermediate product or stamping 10. A composite microwave oven tray of the present invention is shown in FIG.

In this figure, both die-cuts or intermediate products 10 and 30 are joined together. The intermediate products 10 and 30 are the upper surface (metal foil) of the laminate 30 or the lower surface (metal foil) of the laminate 10.
Just put adhesive on either side of the paperboard and assemble.

These two intermediate products are then pressed together, usually with the application of heat to activate the adhesive. Thus, the microwave oven tray of FIG. 5 is constructed from a four-layer laminate. That is, these four layers, from the top of the tray to the bottom, consist of thermoplastic coating, paperboard, aluminum foil, and paperboard.

As best seen in FIG. 5, the top periphery of the aluminum foil does not extend radially outwardly as far as the flange portion 18 of the outermost periphery of the paperboard.

The function of the downwardly bent flange 20 is to further provide protection against arcing. Arcing sometimes occurs between two microwave trays placed edge-to-edge within a microwave oven. The downwardly bent portion 20 also serves to suppress the scorching effect that can occur due to strong dielectric heating of overlapping edges. This scorching effect occurs independently of arcing. Without the downwardly curved edge 20, the metal foil of one tray would extend only the thickness of the paperboard from the metal foil of an adjacent tray. Thus, the downwardly curved edges 20 space the two trays apart enough to eliminate the possibility of arcing between the two trays in most microwave ovens. This increased spacing also reduces the electric field strength in the region of overlapping edges, thus
The degree of scorching in paperboard baking using dielectric heating is limited.

In the preferred embodiments described so far, the thermoplastic is preferably polyethylene terephthalate (P, E,
T, ). Additionally, it was stated that the aluminum foil is sandwiched between at least two paperboard layers. In keeping with the central idea of the present invention, namely that the outer peripheral edge of the metal foil is separated from the outer peripheral edge of the completed tray, the metal foil may be placed inside the tray so as to occupy an upper position within the tray. Therefore, even when applying the thermoplastic coating 22,
Otherwise, the top, or interior, layer of the tray may be aluminum foil, while the bottom layer of the tray may be paperboard.

[Brief explanation of the drawing]

1 is a cross-sectional view of an intermediate laminate product or tray component for forming a tray of the present invention; FIG. 2 is a top view of FIG. 1; and FIG. 3 is a cross-sectional view of an intermediate laminate product or tray component for forming a tray of the present invention. FIG. 4 is a top view of FIG. 3, and FIG. 5 is a cross-sectional view of a tray of the present invention. 10: Intermediate laminate or tray component; 12: Bottom of the paperboard; 14: Central portion with raised bottom; 16: Slanted sides of the paperboard; 18: Flange; 20: Downwardly bent edge; 22; Thermoplastic coating; Intermediate laminated product containing foil, 34. Central raised bottom part, 36: Slanted side wall (aluminum foil layer), 40: Flange, 42: Paperboard layer. Patent applicant International Paper Company

Claims (1)

[Scope of Claims] 1. A first tray layer made of a material that transmits microwave energy and a second tray layer made of a metal foil.
a two-layer laminate is formed by bonding the first tray layer to the second tray layer, and the outer peripheral edge of the metal foil second tray layer is the outer peripheral edge of the first tray layer. The outer periphery of the second tray layer of metal foil is always away from the vertically extending wall of the microwave oven in which the tray is placed, and thus is spaced apart from the outer periphery of the second tray layer of metal foil. A tray for a microwave oven, characterized in that it prevents arcing between the tray and a vertical wall of the microwave oven. 2. The tray of claim 1, wherein the first tray layer is made of paperboard. 3. The tray of claim 1, wherein the first tray layer is above the metal foil tray layer. 4. a third layer, also formed of a material that is transparent to microwave energy and bonded to the metal foil layer, thereby forming a three-layer laminate with the metal foil therebetween; The tray according to claim 2, which constitutes a tray for a microwave oven. 5. The tray according to claim 4, wherein the third layer is formed of paperboard. 6. The tray of claim 1, wherein the outer peripheral edge of the first tray layer has a horizontally extending flange, the flange terminating in a downwardly extending portion. 7. The tray of claim 5 including a thermoplastic top layer on top of said first tray layer.