Abuse-tolerant metallic packaging materials for microwave cooking

• US 6,204,492 B1
• Filed: 09/20/1999
• Issued: 03/20/2001
• Est. Priority Date: 09/20/1999
• Status: Expired due to Term

• Current Assignee: Graphic Packaging International LLC (Graphic Packaging International Incorporated)
• Original Assignee: Graphic Packaging Corporation (Graphic Packaging International Incorporated)
• Inventors: Russell, Anthony, Zeng, Neilson, Lai, Laurence
• Primary Examiner(s): HOANG, TU BA
• Assistant Examiner(s): Pwu, Jeffrey
• Application Number:
  US09/399,182
• Time in Patent Office: 547 Days
• Field of Search: 219/728, 219/729, 219/730, 219/725, 219/759, 219/734, 219/735, 426/107, 426/109, 426/234, 426/243, 426/241, 99/DIG. 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 2581/3472 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: Y10S 99/14 Induction heating

Abstract

An abuse-tolerant microwave food packaging material includes repeated sets of metallic foil or high optical density evaporated material segments disposed on a substrate. Each set of metallic segments is arranged to define a perimeter having a length equal to a predetermined ratio of the operating, or effective wavelength of a microwave oven. The repeated sets of segments act both as a shield to microwave energy and as focusing elements for microwave energy when used in conjunction with food products yet remaining electrically safe in the absence of the food products.

Claims

1. An abuse-tolerant microwave packaging material comprising

a continuously repeated first set of metallic foil segments on a substrate, wherein each first set of metallic segments defines a first perimeter having a length approximately equal to a predetermined ratio of an operating wavelength of a microwave oven, and wherein each segment in each first set is spaced apart from adjacent segments.

2. The abuse-tolerant microwave packaging material of claim 1 wherein the length of the first perimeter is approximately equal to a multiple of one-half of the operating wavelength of the microwave oven.

3. The abuse-tolerant microwave packaging material of claim 1 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the first perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

4. The abuse-tolerant microwave packaging material of claim 1 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the first perimeter is approximately equal to an effective microwave wavelength for thawed food products.

5. The abuse-tolerant microwave packaging material of claim 1 comprising

a continuously repeated second set of metallic foil segments on the substrate, wherein each second set defines a second perimeter enclosing one of the continuously repeated first sets of metallic segments, the second perimeter having a length approximately equal to the predetermined ratio of the operating wavelength of the microwave oven, and wherein each metallic segment of each second set is spaced apart from adjacent segments.

6. The abuse-tolerant microwave packaging material of claim 5 wherein the length of the second perimeter is approximately equal to a multiple of one-half of the operating wavelength of the microwave oven.

7. The abuse-tolerant microwave packaging material of claim 5 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the second perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

8. The abuse-tolerant microwave packaging material of claim 5 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the second perimeter is approximately equal to an effective microwave wavelength for thawed food products.

9. The abuse-tolerant microwave packaging material of claim 5 wherein each second set of metallic segments defines a hexagonal shape.

10. The abuse-tolerant microwave packaging material of claim 5, wherein each of the second sets of metallic segments is nested with adjacent second sets of metallic segments.

11. The abuse-tolerant microwave packaging material of claim 5 comprising

a continuously repeated third set of metallic foil segments on the substrate, wherein each third set defines a third perimeter enclosing one of the repeated second sets of metallic foil segments, the third perimeter having a length approximately equal to the predetermined ratio of the operating wavelength of the microwave oven, and wherein each segment of each third set is spaced apart from adjacent segments.

12. The abuse-tolerant microwave packaging material of claim 11 wherein the length of the third perimeter is approximately equal to a multiple of one-half of the operating wavelength of the microwave oven.

13. The abuse-tolerant microwave packaging material of claim 11, wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the third perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

14. The abuse-tolerant microwave packaging material of claim 11, wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the third perimeter is approximately equal to an effective microwave wavelength for thawed food products.

15. The abuse-tolerant microwave packaging material of claim 11 wherein each third set of metallic segments defines a hexagonal shape.

16. The abuse-tolerant microwave packaging material of claim 11 wherein each of the third sets of metallic segments is nested with adjacent third sets of metallic segments.

17. The abuse-tolerant microwave packaging material of claim 1 wherein each of the repeated first sets of metallic segments defines a multi-lobe shape.

18. The abuse-tolerant microwave packaging material of claim 17 wherein the multi-lobe shape is a five-lobe flower shape.

19. The abuse-tolerant microwave packaging material of claims 1, 5, or 11 wherein each metallic segment has an area less than 5 mm².

20. The abuse-tolerant microwave packaging material of claim 1 wherein the substrate includes a susceptor film.

21. The abuse-tolerant microwave packaging material of claim 1 wherein the substrate is microwave transparent.

22. The abuse-tolerant microwave packaging material of claim 21 wherein the substrate is a paper based material.

23. The abuse-tolerant microwave packaging material of claims 1, 5, or 11 wherein the metallic segments are formed of aluminum.

47. The abuse-tolerant microwave packaging material of claim 5 wherein each of the seconds sets of metallic segments is nested with adjacent second sets of metallic segments.

24. An abuse-tolerant microwave packaging material comprising

a continuously repeated first set of segments formed of a high optical density evaporated material, the repeated first set of segments located on a substrate, wherein each first set of segments defines a first perimeter having a length approximately equal to a predetermined ratio of an operating wavelength of a microwave oven, and wherein each segment in each first set is spaced apart from adjacent segments.

25. The abuse-tolerant microwave packaging material of claim 24 wherein the length of the first perimeter is approximately equal to a multiple of one-half of an operating wavelength of the microwave oven.

26. The abuse-tolerant microwave packaging material of claim 24 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the first perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

27. The abuse-tolerant microwave packaging material of claim 24 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the first perimeter is approximately equal to an effective microwave wavelength for thawed food products.

28. The abuse-tolerant microwave packaging material of claim 24 comprising

a continuously repeated second set of segments formed of the high optical density evaporated material, the repeated second set of segments located on the substrate, wherein each second set defines a second perimeter enclosing one of the continuously repeated first sets of segments, the second perimeter having a length approximately equal to the predetermined ratio of the operating wavelength of the microwave oven, and wherein each segment of each second set is spaced apart from adjacent segments.

29. The abuse-tolerant microwave packaging material of claim 28 wherein the length of the second perimeter is approximately equal to a multiple of one-half of the operating wavelength of the microwave oven.

30. The abuse-tolerant microwave packaging material of claim 28 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the second perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

31. The abuse-tolerant microwave packaging material of claim 28 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the second perimeter is approximately equal to an effective microwave wavelength for thawed food products.

32. The abuse-tolerant microwave packaging material of claim 28 wherein each second set of segments defines a hexagonal shape.

33. The abuse-tolerant microwave packaging material of claim 28 wherein each of the second set of segments is nested with adjacent second sets of segments.

34. The abuse-tolerant microwave packaging material of claim 28 comprising

a continuously repeated third set of segments formed of a high optical density evaporated material, the third set of segments located on the substrate, wherein each third set defines a third perimeter enclosing one of the repeated second sets of segments, the third perimeter having a length approximately equal to the predetermined ratio of the operating wavelength of the microwave oven, and wherein each segment of each third set is spaced apart from adjacent segments.

35. The abuse-tolerant microwave packaging material of claim 34 wherein the length of the third perimeter is approximately equal to a multiple of one-half of the operating wavelength of the microwave oven.

36. The abuse-tolerant microwave packaging material of claim 34 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the third perimeter is approximately equal to one-half of an effective microwave wavelength for frozen food products.

37. The abuse-tolerant microwave packaging material of claim 34 wherein the operating wavelength of the microwave oven comprises an effective microwave wavelength for a food product, and wherein the length of the third perimeter is approximately equal to an effective microwave wavelength for thawed food products.

38. The abuse-tolerant microwave packaging material of claim 34, wherein each third set of segments defines a hexagonal shape.

39. The abuse-tolerant microwave packaging material of claim 34, wherein each of the third sets of segments is nested with adjacent third sets of segments.

40. The abuse-tolerant microwave packaging material of claim 24 wherein each of the repeated first sets of segments defines multi-lobe shape.

41. The abuse-tolerant microwave packaging material of claim 40 wherein the multi-lobe shape is a five-lobe flower shape.

42. The abuse-tolerant microwave packaging material of claims 24, 28, or 34 wherein each metallic segment has an area less than 5 mm².

43. The abuse-tolerant microwave packaging material of claim 24 wherein the substrate includes a susceptor film.

44. The abuse-tolerant microwave packaging material of claim 24 wherein the substrate is microwave transparent.

45. The abuse-tolerant microwave packaging material of claim 44 wherein the substrate is a paper based material.

46. The abuse-tolerant microwave packaging material of claims 24, 28 or 34 wherein the segments of high optical density evaporated material are formed of aluminum.

48. The abuse-tolerant microwave packaging material of claim 34 wherein each of the third set of segments is nested with adjacent third sets of segments.