Microwave interactive laminate

• US 4,865,921 A
• Filed: 06/10/1988
• Issued: 09/12/1989
• Est. Priority Date: 03/10/1987
• Status: Expired due to Term

• Current Assignee: Graphic Packaging International Incorporated
• Original Assignee: James River Corporation of Virginia (KOCH Industries Incorporated)
• Inventors: Hollenberg, David H., Katz, Leon
• Primary Examiner(s): Buffalow, Edith
• Application Number:
  US07/206,961
• Time in Patent Office: 459 Days
• Field of Search: 428/461, 428/458, 428/688, 426/107, 426/234, 426/243, 427/256
• US Class Current: 428/461
• CPC Class Codes: B32B 27/06 as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a layer of a particular substance B32B9/045; next to a bituminous or tarry layer B32B11/046; next to a water setting substance layer B32B13/12; next to a metal layer B32B15/08; next to a glass layer B32B17/10; next to a layer formed of natural mineral fibres or particles B32B19/045; next to a wood layer B32B21/08; next to a cellulosic plastic layer B32B23/08; next to a natural or synthetic rubber layer B32B25/08
• CPC Class Codes: B65D 2581/3447 Heat attenuators, blocking agents or heat insulators for temperature control
• CPC Class Codes: B65D 2581/3464 Microwave reactive material applied by ink printing
• 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 2581/3479 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: Y10T 428/31681 Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]
• CPC Class Codes: Y10T 428/31692 Next to addition polymer from unsaturated monomers

Abstract

Process for chemically modifying microwave interactive film and chemically modified microwave interactive film, chemically modified microwave interactive laminates and packages containing chemically modified microwave interactive film.

Claims

1. In a microwave heater element which comprises a heat stable plastic film coated with a microwave interactive material to form a microwave interactive film, the improvement which comprises and interactivated area in said microwave interactive material wherein the capability of said inactivated area to generate heat in response to microwave energy has been reduced by treatment with an inactivating chemical selected from the group consisting of aqueous solutions of chelating agents, Zr⁺⁴, amines and hydroxy amines, and dilute bases, dilute acids, metal salts, and mixtures thereof followed by drying.

2. A microwave interactive film as defined in claim 1 wherein said inactivated area of said microwave interactive material has been treated with an inactivating chemical in an amount sufficient to prevent said inactivated area from generating heat in response to microwave energy.

3. A microwave interactive film as defined in claim 1 wherein said microwave interactive material is selected from the group consisting of iron, nickel, copper, silver, carbon, stainless steel, nichrome, magnetite, zinc, tin, tungsten, titanium, and aluminum.

4. A microwave interactive film as defined in claim 3 wherein said inactivating chemical is selected from the group consisting of EDTA, DTPA, and HOEDTA.

5. A microwave interactive film as defined in claim 3 wherein said inactivating chemical is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, choline, and salts of the ethanolamines and choline.

6. A microwave interactive film as defined in claim 3 wherein said inactivating chemical is selected from the group consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium and potassium carbonates, and sodium and potassium phosphates.

7. A microwave interactive film as defined in claim 3 wherein said inactivating chemical is selected from the group consisting of acetic, formic, hydrochloric, hydrofluoric, citric, tartaric, oxalic, and succinic acids and salts thereof.

8. A microwave interactive film as defined in claim 3 wherein said inactivating chemical is selected from the group consisting of ferric chloride, ferric sulphate, ferrous chloide, ferrous ammonium sulphate, ammonium fluoride, sodium fluoride, zinc chloride, and zinc oxide.

9. A microwave interactive film as defined in claim 1 wherein the microwave interactive material is aluminum.

10. A microwave interactive film as defined in claim 9 wherein the inactivating chemical is a base.

11. A microwave interactive film as defined in claim 9 wherein the activating chemical is an alkali metal hydroxide.

12. A microwave interactive laminate which has been treated with an inactivating chemical, comprising:

a microwave interactive film layer which comprises a heat stable plastic film coated with a microwave interactive material having an inactivated area wherein the capability of said inactivated area to generate heat in response to microwave energy has been reduced by treatment with an inactivating chemical selected from the group consisting of aqueous solutions of chelating agents, Zr⁺⁴, amines and hydroxy amines, and dilute bases, dilute acids, metal salts, and mixtures thereof followed by drying, and

a substrate layer bonded to said microwave interactive film layer to form a microwave interactive laminate, wherein said microwave interactive material is disposed between said heat stable plastic film layer and said substrate layer.

13. A microwave interactive laminate as defined in claim 12 wherein said inactivated area of said microwave interactive material has been treated with an inactivating chemical in an amount sufficient to prevent said inactivated area from generating heat in response to microwave energy.

14. A microwave interactive film as defined in claim 13 wherein said microwave interactive material is selected from the group consisting of iron, nickel, copper, silver, carbon, stainless steel, nichrome, magnetite, zinc, tin, tungsten, titanium, and aluminum.

15. A microwave interactive film as defined in claim 14, wherein said inactivating chemical is selected from the group consisting of EDTA, DTPA, and HOEDTA.

16. A microwave interactive film as defined in claim 14 wherein said inactivating chemical is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, choline, and salts of the ethanolamines and choline.

17. A microwave interactive film as defined in claim 14 wherein said inactivating chemical is selected from the group consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium and potassium carbonates, and sodium and potassium phosphates.

18. A microwave interactive film as defined in claim 14 wherein said inactivating chemical is selected from the group consisting of acetic, formic, hydrochloric, hydrofluoric, citric, tartaric, oxalic, and succinic acids and salts thereof.

19. A microwave interactive film as defined in claim 14 wherein said inactivation chemical is selected from the group consisting of ferric chloride, ferric sulphate, ferrous chloride, ferrous ammonium sulphate, ammonium fluoride, sodium fluoride, zinc chloride, and zinc oxide.

20. A microwave interactive laminate as defined in claim 12 wherein said substrate is selected from the group consisting of paperboard, paper, and fiber/polymer composites.

21. A microwave interactive laminate as defined in claim 12 wherein the microwave interactive material is aluminum.

22. A microwave interactive laminate as defined in claim 21 wherein the inactivating chemical is a base.

23. A microwave interactive laminate as defined in claim 21 wherein the inactivating chemical is an alkali metal hydroxide.

24. A microwave laminate as defined in claim 12 wherein said substrate layer is bonded to said microwave interactive film with an adhesive selected from the group consisting of water-based acrylic emulsions, casein emulsions and neoprene emulsions.