Abuse-tolerant metallic pattern arrays for microwave packaging materials

• US 6,677,563 B2
• Filed: 12/14/2001
• Issued: 01/13/2004
• Est. Priority Date: 12/14/2001
• Status: Expired due to Term

• Current Assignee: Graphic Packaging International Incorporated
• Original Assignee: Graphic Packaging Corporation
• Inventors: Lai, Laurence M. C.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US10/017,374
• Publication Number:
  US 20030111463A1
• Time in Patent Office: 760 Days
• Field of Search: 219/730, 219/729, 219/728, 219/732, 219/762, 219/725, 219/733, 219/735, 426/107, 426/234, 426/243, 426/109, 426/241, 426/118, 99D/IG.14
• US Class Current: 219/728
• CPC Class Codes: B65D 2581/344 Geometry or shape factors influencing the microwave heating properties
• CPC Class Codes: B65D 2581/3454 Microwave reactive layer having a specified optical density
• CPC Class Codes: B65D 2581/3466 Microwave reactive material applied by vacuum, sputter or vapor deposition
• 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 2581/3487 Reflection, Absorption and Transmission [RAT] properties of the microwave reactive package
• CPC Class Codes: B65D 2581/3489 Microwave reflector, i.e. microwave shield B65D2581/3487 takes precedence
• 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

Abstract

An abuse-tolerant microwave food packaging material includes an array of solid shapes of microwave energy reflective material, for example, of aluminum foil, disposed on a substrate. The an array of shapes of microwave energy reflective material shield microwave energy from a food product while remaining substantially resistant to arcing or burning under abusive cooking conditions in an operating microwave oven.

Claims

1. An abuse-tolerant microwave packaging material comprising:

a substrate; and

a plurality of uniform solid shapes comprised of microwave energy reflective material arranged in an array, wherein said array is supported by said substrate;

wherein each of said plurality of solid shapes further comprises;

a respective predetermined shape; and

a respective predetermined size; and

wherein each of said plurality of solid shapes in said array is spaced apart from each adjacent shape by a respective predetermined spacing; and

wherein a combination of said predetermined shape, said predetermined size, and said predetermined spacing provides substantial resistance to arcing or burning of said packaging material under abusive looking conditions in an operating microwave oven.

2. The abuse-tolerant microwave packaging material as described in claim 1, further comprising a microwave interactive material layer supported by said substrate.

3. The abuse-tolerant microwave packaging material as described in claim 2, wherein said microwave interactive material layer comprises a susceptor film.

4. The abuse-tolerant microwave packaging material as described in claim 3, wherein said susceptor film comprises a deposition of aluminum on a microwave transparent substrate.

5. The abuse-tolerant microwave packaging material as described in claim 1, wherein said microwave energy reflective material comprises a metal foil.

6. The abuse-tolerant microwave packaging material as described in claim 5, wherein said metal foil comprises aluminum foil.

7. The abuse-tolerant microwave packaging material as described in claim 1, wherein said microwave energy reflective material comprises a high optical density evaporated material deposited on a microwave transparent substrate.

8. The abuse-tolerant microwave packaging material as described in claim 7, wherein said high optical density evaporated material comprises aluminum.

9. The abuse-tolerant microwave packaging material as described in claim 1, wherein said predetermined shape comprises a shape selected from the group of shapes comprising:

a circle, an oval, a curvilinear shape, a symmetrical curvilinear shape, a triangle, a square, a rectangle, a polygon, a right polygon, and an equilateral polygon.

10. The abuse-tolerant microwave packaging material as described in claim 9, wherein said equilateral polygon is a hexagon.

11. The abuse-tolerant microwave packaging material as described in claim 1, wherein each of said plurality of solid shapes in said array is nested with each said adjacent shape in said array in a tile-like pattern.

12. The abuse-tolerant microwave packaging material as described in claim 11, wherein said predetermined spacing is a distance of about 1 mm.

13. The abuse-tolerant microwave packaging material as described in claim 1, wherein said predetermined spacing comprises an equal distance apart from and with respect to each said adjacent shape in said array.

14. The abuse-tolerant microwave packaging material as described in claim 1, wherein said predetermined size is about 4 mm in width.

15. The abuse-tolerant microwave packaging material as described in claim 1, wherein said substrate is microwave transparent.

16. The abuse-tolerant microwave packaging material as described in claim 1, wherein said substrate is selected from a group of substrates comprising:

paper, paperboard, plastic, glass, and ceramic.

17. The abuse-tolerant microwave packaging material as described in claim 3, wherein said packaging material reflects between 80 and 85 percent of microwave energy incident upon said microwave packaging material when said microwave packaging material is placed in said operating microwave oven.

18. A method of manufacturing a microwave packaging material comprising:

providing a substrate; and

adhering a microwave energy reflective layer to said substrate;

wherein said microwave energy reflective layer comprises a plurality of uniform solid shapes comprised of microwave energy reflective material arranged in an array; and

wherein each of said plurality of shapes further comprises;

a respective predetermined shape; and

a respective predetermined size; and

wherein each of said plurality of solid shapes in said array is spaced apart from each adjacent shape by a respective predetermined spacing; and

wherein a combination of said predetermined shape, said predetermined size, and said predetermined spacing provides substantial resistance to arcing by or burning of said microwave packaging material under abusive cooking conditions in an operating microwave oven.

19. The method as described in claim 18, further comprising cutting said microwave packaging material into a packaging shape.

20. The method as described in claim 19, further comprising compression molding said microwave packaging material to create a pan or tray with sidewalls.

21. The method as described in claim 18, further comprising adhering a microwave interactive material layer to said microwave energy reflective layer.

22. The method as described in claim 21, wherein said microwave interactive material layer comprises a susceptor film.

23. The method as described in claim 22, wherein said susceptor film comprises a deposition of aluminum on a microwave transparent substrate.

24. The method as described in claim 18, wherein said microwave energy reflective material comprises a metal foil.

25. The method as described in claim 24, wherein said metal foil comprises aluminum foil.

26. The method as described in claim 18, wherein said microwave energy reflective material comprises a high optical density evaporated material deposited on a microwave transparent substrate.

27. The method as described in claim 26, wherein said high optical density evaporated material comprises aluminum.

28. The method as described in claim 18, wherein said predetermined shape comprises a shape selected from the group of shapes comprising:

a circle, an oval, a curvilinear shape, a symmetrical curvilinear shape, a triangle, a square, a rectangle, a polygon, a right polygon, and an equilateral polygon.

29. The method as described in claim 28, wherein said equilateral polygon is a hexagon.

30. The method as described in claim 18, wherein each of said plurality of solid shapes in said array is nested with each said adjacent shape in said array in a tile-like pattern.

31. The method as described in claim 18, wherein said predetermined spacing comprises an equal distance apart from and with respect to each said adjacent shape in said array.

32. The method as described in claim 31, wherein said predetermined spacing is a distance of about 1 mm.

33. The method as described in claim 18, wherein said predetermined size is about 4 mm in width.

34. The method as described in claim 18, wherein said substrate is microwave transparent.

35. The method as described in claim 18, wherein said substrate is selected from a group of substrates comprising:

paper, paperboard, plastic, glass, and ceramic.

36. The method as described in claim 22, wherein said microwave packaging material reflects between 80 and 85 percent of microwave energy incident upon said packaging material when said packaging material is placed in said operating microwave oven.

37. An abuse-tolerant microwave shielding material comprising:

a substrate;

an array of uniform solid shapes of microwave reflective material supported upon said substrate;

wherein each of said solid shapes further comprises;

a respective predetermined shape; and

a respective predetermined size; and

wherein each of said solid shapes in said array is spaced apart from each adjacent solid shape by an equal distance with respect to each adjacent solid shape; and

a susceptor film supported upon said substrate;

wherein said abuse-tolerant microwave shielding material reflects between 80 and 85 percent of microwave energy incident upon said shielding material when said shielding material is placed in an operating microwave oven; and

wherein a combination of said predetermined shape, said predetermined size, and said spacing provides substantial resistance to arcing by or burning of said abuse-tolerant microwave shielding material under abusive cooking conditions in said operating microwave oven.

38. The abuse-tolerant microwave shielding material of claim 37, wherein said predetermined shape comprises a shape selected from the group of shapes comprising:

a circle, an oval, a curvilinear shape, a symmetrical curvilinear shape, a triangle, a square, a rectangle, a polygon, a right polygon, and an equilateral polygon.

39. The abuse-tolerant microwave shielding material as described in claim 38, wherein said equilateral polygon is a hexagon.

40. The abuse-tolerant microwave shielding material as described in claim 37, wherein said substrate is selected from the group comprising:

paper, paperboard, plastic, glass, and ceramic.

41. An improvement to reusable, microwave-safe cookware, the improvement comprising:

an abuse-tolerant microwave shielding material further comprising

a substrate;

an array of uniform solid shapes of microwave reflective material supported upon said substrate;

wherein each of said solid shapes further comprises;

a respective predetermined shape; and

a respective predetermined size; and

wherein each of said solid shapes in said array is spaced apart from each adjacent solid shape by an equal distance with respect to each adjacent solid shape; and

a susceptor film supported upon said substrate;

wherein said abuse-tolerant microwave shielding material is applied to said reusable cookware;

wherein said abuse-tolerant microwave shielding material reflects between 80 and 85 percent of microwave energy incident upon said shielding material when said microwave-safe cookware is placed in an operating microwave oven; and

wherein a combination of said predetermined shape, said predetermined size, and said spacing provides substantial resistance to arcing by or burning of said abuse-tolerant microwave shielding material under abusive cooking conditions in said operating microwave oven.

42. The improvement as described in claim 41, further comprising a microwave interactive material layer supported by said substrate.

43. The improvement as described in claim 41, wherein said reusable cookware comprises ceramic cookware.

44. The improvement as described in claim 41, wherein the reusable cookware comprises glass cookware.

45. The improvement as described in claim 44, wherein:

said glass cookware is further comprised of;

a first layer of glass; and

a second layer of glass; and

wherein said abuse-tolerant microwave shielding material is sandwiched between said first layer of glass and said second layer of glass.