Adhesiveless susceptor films and packaging structures

• US 5,217,768 A
• Filed: 09/05/1991
• Issued: 06/08/1993
• Est. Priority Date: 09/05/1991
• Status: Expired due to Fees

• Current Assignee: Advanced Deposition Technologies, Inc.
• Original Assignee: Advanced Dielectric Technologies, Inc.
• Inventors: Walters, Glenn J., Walters, Gordon E.
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): Bahta, Abraham
• Application Number:
  US07/755,157
• Time in Patent Office: 642 Days
• Field of Search: 426/107, 428/35.08, 428/461, 428/107, 428/323
• US Class Current: 428/35.8
• CPC Class Codes: B32B 2255/12 on paper layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/10 of paper or cardboard
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B65D 2581/3447 Heat attenuators, blocking agents or heat insulators for temperature control
• CPC Class Codes: B65D 2581/3458 Convective heating chambers, e.g. hot air channels
• CPC Class Codes: B65D 2581/3466 Microwave reactive material applied by vacuum, sputter or vapor deposition
• CPC Class Codes: B65D 2581/3472 Aluminium or compounds thereof
• CPC Class Codes: B65D 2581/3474 Titanium or compounds thereof
• CPC Class Codes: B65D 2581/3477 Iron or compounds thereof
• CPC Class Codes: B65D 2581/3478 Stainless steel
• CPC Class Codes: B65D 2581/3479 Other metallic compounds, e.g. silver, gold, copper, nickel
• 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: B65D 81/3853 formed with double walls, i.e. hollow
• CPC Class Codes: Y10T 428/1307 Bag or tubular film [e.g., pouch, flexible food casing, envelope, etc.]
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1355 Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/24074 : Strand or strand-portions
• CPC Class Codes: Y10T 428/24917 : including metal layer
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/31692 : Next to addition polymer from unsaturated monomers

Abstract

A susceptor composite and related packaging devices employing the susceptor composite comprising a plurality of heat sealable layers is disclosed. The susceptor composite is adhesiveless and is used in food packages for heating and cooking food products in a microwave oven. In one preferred embodiment, a first substrate of amorphous polyester has a metallic microwave absorptive layer deposited on one of its surfaces. A dimensionally stable layer that includes a heat sealable material is heat sealed to at least one of the first substrate and microwave absorptive layer. The heat sealable film can be applied in a pattern and can also be applied using different heat-sealing temperatures to provide selective microwave absorption to the susceptor composite of the invention.

Claims

1. A package material for use in microwave packaging and cooking of food, comprising:

a susceptor including;

a first substrate with opposed first and second surfaces, said first substrate formed of a heat-sealable material that is transparent to microwaves and that maintains its heat sealable properties at temperatures up to about 500°

F.; and

a microwave absorptive substrate for receiving microwave energy, the microwave absorptive material covering a sufficient area of the first substrate so that the susceptor will heat when exposed to microwaves; and

a dimensionally stable second substrate including a heat-sealable material, the second substrate heat-sealed to at least the second surface of the first substrate.

2. The package material of claim 1, wherein the heat-sealable polymeric- material is an amorphous polyester.

3. The package material of claim 2, wherein the microwave absorptive material comprises a metal-containing material selected from the group consisting of a single metal, a metal alloy, a metal oxide, a mixture of metal oxides, a dispersion of metals, and any combination of the foregoing.

4. The package material of claim 2, wherein the second substrate is selected from the group consisting of paper, amorphous polyester-coated paper, and clay-coated paper.

6. The package material of claim 1, wherein said dimensionally stable second substrate is heat-sealed to a surface of the first substrate to provide a configuration in which the microwave absorptive layer and first substrate are heat-sealed between layers of dimensionally stable second substrates.

7. The composite of claim 6, wherein the heat-sealable material is an amorphous polyester.

8. The composite of claim 1, wherein said first substrate that is heat-sealed is in the form of a geometric pattern, the pattern providing selective absorption of microwave energy so that only a part of the microwave energy contacting can pass through the composite.

9. The composite of claim 7, wherein the microwave absorptive layer comprises a metal-containing material selected from the group consisting of a single metal, a metal alloy, a metal oxide, a mixture of metal oxides, a dispersion of metals, and any combination of the foregoing.

13. The package material of claim 1, wherein said dimensionally stable second substrate is heat-sealed to a peripheral portion of said first substrate.

5. A composite for use in a microwave oven formed into a shape sufficient to enclose a food product to be cooked, the composite comprising:

a flexible first substrate, the first substrate comprising a heat-sealable polymeric material having opposed first and second surfaces, the material transparent to microwaves; and

a microwave absorptive layer deposited on the first surface of the first substrate, the microwave absorptive layer covering a sufficient area of the first surface so that the composite will heat when microwaves contact the absorptive layer;

a dimensionally stable second substrate comprising a heat-sealable material that is heat-sealed to the microwave absorptive layer.

10. A package for cooking a food product in a microwave oven, comprising:

a first substrate having opposed first and second surfaces, the first substrate comprising a heat-sealable amorphous polyester having the characteristics of Table I;

a microwave absorptive layer affixed to a first surface of the first substrate, the microwave absorptive layer comprising a material that increases in temperature when exposed to microwave energy; and

a dimensionally stable second substrate comprising a material that includes a heat-sealable amorphous polyester having the characteristics of a density of 1.26 (g/cc), a melt point of 265°

C., elongation of 300-500% and secant modulus of 1430 Mpa, the dimensionally stable second substrate heat-sealed to at least the microwave absorptive layer.

11. An adhesiveless susceptor film comprising a plurality of layers, aid adhesiveless susceptor film comprising a first substrate layer that includes an amorphous polyester, said layer having opposed surfaces, said first substrate layer having a microwave energy-absorptive layer deposited on one of said opposed surfaces;

and a dimensionally stable substrate layer containing a heat-sealable material that is heat-sealed to at least said microwave absorptive layer, wherein adjacent layers that are heat-sealed to each other are heat-sealed to each other on only a portion of their respective surface areas.

12. The adhesiveless susceptor of claim 11, wherein said first substrate layer is in the form of a geometric pattern, the pattern providing varying degrees of resistivity of said absorptive layer, so that only a part of the microwave energy can pass through the adhesiveless susceptor film.

14. The susceptor of claim 17, wherein said adjacent layers are heat-sealed to each other at their respective peripheral surfaces.