Microwave heating structure comprising an array of shaped elements

• US 5,354,973 A
• Filed: 01/29/1993
• Issued: 10/11/1994
• Est. Priority Date: 01/29/1992
• Status: Expired due to Term

• Current Assignee: Graphic Packaging International Incorporated
• Original Assignee: Beckett Industries, Inc.
• Inventors: Beckett, D. Gregory
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US08/010,803
• Time in Patent Office: 620 Days
• Field of Search: 219/10.55 E, 219/10.55 F, 219/728, 219/729, 219/730, 219/759, 426/107, 426/109, 426/111, 426/234, 426/241, 426/243, 99/DIG. 14
• US Class Current: 219/730
• CPC Class Codes: B65D 2581/344 Geometry or shape factors influencing the microwave heating properties
• CPC Class Codes: B65D 2581/3467 Microwave reactive layer shaped by delamination, demetallizing or embossing
• CPC Class Codes: B65D 2581/3472 Aluminium or compounds thereof
• CPC Class Codes: B65D 2581/3494 Microwave susceptor B65D2581/3487 takes precedence
• CPC Class Codes: B65D 81/3446 specially adapted to be heated by microwaves
• CPC Class Codes: H05B 6/64 Heating using microwaves containers, packaging elements or packages specially adapted to be heated by microwaves B65D81/3446
• CPC Class Codes: Y10S 99/14 Induction heating

Abstract

A novel structure for use in the microwave cooking of foodstuffs for consumption is described. The structure includes an array of individual shapes of flexible electroconductive material normally opaque to microwave radiation supported on a microwave transparent substrate. Each of the individual discrete shapes of flexible electroconductive material has a thickness normally opaque to microwave radiation and is formed in an H-, I- or elongate strip shape. The individual discrete shapes are arranged on the substrate to define a space surrounding the periphery of each individual shape with the spaces defining a continuous aperture extending throughout the array and effective to generate thermal energy in the continuous aperture when the article is exposed to microwave energy and the foodstuff is in contact with or proximate to the aperture. The multiple layer article of manufacture is adapted to be formed into a packaging structure in which a foodstuff may be heated by microwave energy to an edible condition.

Claims

1. A multiple layer article of manufacture, adapted to be formed into a packaging structure in which a foodstuff may be heated by microwave energy to a edible condition, comprising:

a plurality of individual discrete shapes of flexible electroconductive material supported in an array on a substrate layer,

each said individual discrete shapes of flexible electroconductive material having a thickness which is normally opaque to microwave radiation and being formed in an H- or I- outline or elongate-strip shape,

said individual discrete shapes being arranged on said substrate to define a space surrounding the periphery of each individual shape with the spaces surrounding the plurality of shapes defining a continuous aperture extending throughout the array of discrete shape and effective to generate thermal energy in said continuous aperture when said article is exposed to microwave energy and the foodstuff is in contact with or proximate to the aperture,

said substrate layer being formed of microwave energy transparent material and being in adhered structural relationship with said plurality of individual discrete shapes of flexible electroconductive material so that a packaging structure may be formed from said article in which said foodstuff may be positioned.

2. The structure of claim 1 wherein said individual discrete shape of flexible electroconductive material have an H- or I- outline and are interfitted in said array.

3. The structure of claim 2 wherein each of the individual discrete shapes has the same dimensions and are arranged in a uniform array.

4. The structure of claim 3 wherein each of the individual discrete shapes has a pair of arms and at element joining the arms, each individually dimensioned for about 1/64 to about 7 inches.

5. The structure of claim 1 wherein each individual discrete shape of flexible electroconductive material is an elongate strip and are arranged in a uniform array.

6. The structure of claim 5 wherein each strip has a longitudinal dimension and a lateral dimension individually from about 1/64 to about 7 inches and each said strip is laterally and longitudinally spaced apart from each adjacent strip by about 1/64 to about 7 inches.

7. The article of claim 1 wherein said flexible electroconductive material has a thickness of at least about 1 micron.

8. The article of claim 1 wherein electroconductive material is aluminum foil having a thickness of from about 1 to about 15 microns.

9. The article of claim 8 wherein said aluminum foil has a thickness of about 3 to about 10 microns.

10. The article of claim 8 wherein said substrate layer is formed of microwave transparent structural stock material.

11. The article of claim 10 wherein said structural stock material is paper or paperboard.

12. The article of claim 11 wherein said stock material is provided on one side of the layer of electroconductive material and a polymeric film is provided on the other.

13. The article of claim 11 wherein said structural stock material is provided on both sides of the layer of electroconductive material.

14. The article of claim 1 wherein said electroconductive material is laminated between outer layers of polymeric material.

15. The article of claim 14 wherein at least one of said polymeric material layers is formed of rigid moldable material.

16. The article of claim 1 wherein a layer of electroconductive material having a thickness sufficient small as to effect conversion of a portion of incident microwave energy to thermal energy is positioned in engagement with said substrate layer to achieve an augmented heating effect from said array by exposure of said layer of electroconductive material to microwave energy.

17. The article of claim 1 wherein said microwave transparent layer comprises a polymeric film layer to which said electroconductive material is adhered by laminating adhesive.

18. The article of claim 17 wherein said continuous aperture is formed by selective demetallization.

19. The article of claim 18 wherein said electroconductive material is coated with a layer of detackifying material for said laminating adhesive following said selective demetallization.

20. The article of claim 18 wherein a layer of food release material is provided on food-contacting areas of said polymeric film layer on the opposite side thereof from that to which said electroconductive material is adhered.