Insulating microwave interactive packaging

• US 20080078759A1
• Filed: 10/31/2007
• Published: 04/03/2008
• Est. Priority Date: 02/08/2002
• Status: Active Grant

• Current Assignee: Graphic Packaging International Incorporated
• Original Assignee: Graphic Packaging International Incorporated
• Inventors: Robison, Richard, Lafferty, Terrence, Middleton, Scott, O'Hagan, Brian, Cole, Lorin, Wnek, Patrick
• Granted Patent: US 7,923,669 B2
• Time in Patent Office: Days
• US Class Current: 219/730
• CPC Class Codes: B32B 27/10 of paper or cardboard
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 29/00 Layered products comprising a layer of paper or cardboard
• CPC Class Codes: B65D 2581/344 Geometry or shape factors influencing the microwave heating properties
• CPC Class Codes: B65D 2581/3447 Heat attenuators, blocking agents or heat insulators for temperature control
• CPC Class Codes: B65D 2581/3456 Means for holding the contents at a distance from the base of the package, e.g. raised islands or protrusions B65D2581/3459 takes precedence
• CPC Class Codes: B65D 2581/3458 Convective heating chambers, e.g. hot air channels
• CPC Class Codes: B65D 2581/3462 separate from the package, e.g. separate stands
• 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 2581/3489 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 2585/366 Pizza
• CPC Class Codes: B65D 5/52 External stands or display elements for contents
• CPC Class Codes: B65D 5/5455 the lines of weakness being provided in a closure hinged to an edge of the container body
• CPC Class Codes: B65D 81/3453 Rigid containers, e.g. trays, bottles, boxes, cups
• CPC Class Codes: B65D 81/3461 Flexible containers, e.g. bags, pouches, envelopes
• CPC Class Codes: B65D 81/3823 formed of different materials, e.g. laminated or foam filling between walls
• CPC Class Codes: B65D 81/3893 formed with double walls, i.e. hollow
• CPC Class Codes: H05B 6/6494 : for cooking
• CPC Class Codes: Y10S 99/14 : Induction heating
• CPC Class Codes: Y10T 428/249921 : Web or sheet containing structurally defined element or component

Abstract

The combination of insulating material with microwave interactive food packaging for enhanced cooking properties is disclosed. An insulating microwave packaging material (200) and a method of making the same are also disclosed. In one embodiment, the insulating microwave packaging material (200) is formed by bonding a microwave interactive material substrate (205) that creates sensible heat upon exposure to microwave energy to a second substrate (210) along bond lines (212) arranged in a pattern to form closed cells (214). Upon impingement of the insulating microwave packaging material (200) by microwave energy in a microwave oven, the closed cells (214) expand to form insulating pockets (216). One side of the insulating pocket (216) bulges and lofts above the opposite side. When a food product is situated on the insulating microwave packaging material (200), the insulating pockets (216) insulate the food product from the microwave oven environment.

Claims

1. A microwavable baking surface comprising:

a baking substrate containing an aperture;

a first sheet of an insulating microwave packaging material; and

a second sheet of the insulating microwave packaging material;

wherein

the first sheet and the second sheet are arranged adjacent to each other and substantially cover the aperture,

the insulating microwave packaging material includes

a layer of microwave energy interactive material supported on a first polymer film,

a dimensionally stable substrate joined to the layer of microwave energy interactive material, and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film, and

upon sufficient exposure to microwave energy,

at least some of the closed cells inflate, and

the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film.

2. The microwavable baking surface of claim 1, wherein

the first sheet is adapted to receive a food item for heating, and

the inflated closed cells of the second sheet reduce heat loss from at least one of the food item and the first sheet.

3. The microwavable baking surface of claim 1, wherein the second polymer film of the first sheet faces the second polymer film of the second sheet.

4. The microwavable baking surface of claim 1, wherein

the baking substrate includes a upper surface and a lower surface,

the first sheet and the second sheet each have a peripheral region,

at least a portion of the peripheral region of the second polymer film of the first sheet is joined to the upper surface of the baking substrate, and

at least a portion of the peripheral region of the second polymer film of the second sheet is joined to the lower surface of the baking substrate.

5. The microwavable baking surface of claim 4, wherein at least one of the first sheet and the second sheet is joined to the baking substrate using an adhesive that softens in response to temperature.

6. The microwavable baking surface of claim 1, wherein

upon impingement of the insulating microwave packaging material by microwave energy, the first sheet deforms into a convex canopy with respect to a plane dividing the first sheet and the second sheet, and

a space is created between the first sheet and the second sheet.

7. The microwavable baking surface of claim 1, wherein

upon impingement of the insulating microwave packaging material by microwave energy, the second sheet deforms into a convex canopy with respect to a plane dividing the first sheet and the second sheet, and

a space is created between the first sheet and the second sheet.

space is created between the first sheet and the second sheet.

8. The microwavable baking surface of claim 1, wherein the baking substrate comprises paperboard.

9. The microwavable baking surface of claim 1, wherein the baking substrate comprises a susceptor.

10. The microwavable baking surface of claim 1, wherein the baking substrate comprises an abuse-tolerant microwave packaging material.

11. The microwavable baking surface of claim 1, wherein the baking substrate is disk-shaped.

12. The microwavable baking surface of claim 11, wherein the aperture is circular and concentric with the baking surface.

13. A microwave cooking container comprising:

a body formed from a dimensionally stable material, the body including

at least one wall at least partially covered by a microwave energy interactive material,

a floor adapted to support a food item, and

an opening opposite the floor; and

a base adapted to support the body, the base including a venting aperture.

14. The microwave cooking container of claim 13, wherein

the microwave energy interactive material is supported on a polymer film, and

the polymer film defines at least a portion of an interior surface of the body.

15. The microwave cooking container of claim 13, wherein

the microwave energy interactive material is supported on a first polymer film,

a moisture-containing substrate is joined to the microwave energy interactive material, and

a second polymer film is joined to the moisture-containing substrate in a patterned configuration that defines a plurality of expandable insulating cells.

16. The microwave cooking container of claim 15, wherein upon sufficient exposure to microwave energy, at least some cells of the plurality of expandable insulating cells inflate.

17. The microwave cooking container of claim 13, wherein

the body includes an interior surface and an exterior surface opposite the interior surface, and

the exterior surface comprises a thermal insulating material.

18. The microwave cooking container of claim 13, wherein

the body comprises an upper portion and a lower portion, and

the upper portion and the lower portion are each of separate construction, and

the upper portion is attached to the lower portion at a common interface between the upper portion and the lower portion.

19. The microwave cooking container of claim 18, wherein

the upper portion and the lower portion each include an interior surface, and

the interior surface of at least one of the upper portion and the lower portion is corrugated.

20. The microwave cooking container of claim 18, wherein

the upper portion and the lower portion each independently include a major opening having a rim, and

the upper portion and the lower portion are arranged in an opposed relationship such that the respective major openings of the upper portion and the lower portion cup are adjacent and open to one other.

21. The microwave cooking container of claim 20, wherein

the respective rims of the first cup and the second cup each independently comprise a lip extending outwardly from the exterior surface thereof, and

the respective rims are aligned substantially and in contact with each other.

22. The microwave cooking container of claim 20, wherein

the upper portion and the lower portion each independently include an end distal to the major opening, and

the upper portion and the lower portion are capable of being stacked in a nested configuration with the respective major openings adjacent to one another and the respective ends being adjacent one another.

23. A microwavable package for heating a food item, the package comprising:

a canister having an interior surface, an exterior surface, and a cavity capable of receiving a food item, at least a portion of the interior surface including a microwave energy interactive material,

wherein the canister comprises a first cup and a second cup, the first cup and the second cup each independently including a major opening having a rim, the first cup and the second cup being arranged in an opposed relationship such that the respective major openings of the first cup and the second cup are adjacent and open to one other.

24. The microwavable package of claim 23, wherein the respective rims of the first cup and the second cup are aligned substantially and in contact with each other.

25. The microwavable package of claim 23, wherein the rim of at least one of the first cup and the second cup comprises a lip extending outwardly from the exterior surface thereof.

26. The microwavable package of claim 23, wherein

the respective rims of the first cup and the second cup each independently comprise a lip extending outwardly from the exterior surface thereof, and

the respective rims are aligned substantially and in contact with each other.

27. The microwavable package of claim 23, wherein

the rim of the first cup comprises a flange including a shelf, and

the rim of the second cup is aligned with the shelf of the first cup.

28. The microwavable package of claim 23, wherein the respective rims of the first cup and the second cup are joined separably by an adhesive.

29. The microwavable package of claim 23, wherein the respective rims of the first cup and the second cup are joined separably by a removable plastic tear-tape on at least a portion of the exterior surface of the package.

30. The microwavable package of claim 23, wherein the first cup is joined to the second cup using a plastic shrink-wrap.

31. The microwavable package of claim 23, wherein at least one of the first cup and the second cup includes a flattened end distal the rim thereof.

32. The microwavable package of claim 23, wherein

the first cup and the second cup are arranged in an upright configuration such that one of the first cup and the second cup serves as a bottom cup, and

the bottom cup comprises a flattened end distal the rim thereof.

33. The microwavable package of claim 23, wherein at least one of the first cup and the second cup includes a vent window.

34. The microwavable package of claim 23, wherein the microwave energy interactive material comprises a susceptor.

35. The microwavable package of claim 23, wherein at least a portion of only one of the first cup and the second comprises the microwave energy interactive material.

36. The microwavable package of claim 23, wherein at least a portion of both first cup and the second cup independently comprises the microwave energy interactive material.

37. The microwavable package of claim 23, wherein at least a portion of the exterior surface of the package comprises an insulating material.

38. The microwavable package of claim 23, wherein

at least a portion of the interior surface of at least one of the first cup and the second cup is corrugated, and

at least a portion of the microwave energy active material is deposited on the corrugated surface.

39. The microwavable package of claim 23, wherein

the first cup and the second cup each independently comprise an end distal the major opening, and

the first cup and the second cup are capable of being stacked in a nested configuration with the respective major openings adjacent to one another and the respective ends being adjacent one another.

40. A microwavable package for heating a food item, the package comprising:

a first portion adapted to receive a food item, the first portion having an interior surface at least partially comprising a microwave energy interactive material;

a second portion dimensioned to be gripped by a user; and

a wall separating the first portion and the second portion.

41. The microwavable package of claim 40, wherein at least one of the first portion and the second portion includes a venting feature.

42. The microwavable package of claim 40, wherein the first portion comprises a removable sheet for accessing a food item therein.

43. The microwavable package of claim 40, wherein the first portion and the second portion are arranged in an upright configuration, such that the first portion is an upper portion, the second portion is a lower portion, and the wall separating the first portion and the second portion serves as a floor of the upper portion.

44. The microwavable package of claim 40, wherein the lower portion is tapered from the upper portion towards a bottom end of the lower portion.

45. The microwavable package of claim 40, wherein the bottom end of the lower portion is flattened.

46. A microwave package comprising:

a carton form including

a base with a central fold line,

a first side wall foldably joined to the base along a first fold line, and

a second side wall foldably joined to the base along a second fold line; and

a pouch disposed between the base, the first side wall, and the second side wall of the carton form, the pouch comprising a microwave energy interactive material.

47. The package of claim 46, wherein the carton form and the pouch may be transformed from a first, flattened configuration to a second, erected configuration with the first side wall and the second side wall being maintained in tension by the base.

48. The package of claim 46, wherein

the first fold line and the second fold line are convexly curved, and

in the second configuration, the base of the carton form assumes a, concavely curved form with the first side wall and the second side wall of the carton form being bowed or convexly curved.

49. The package of claim 46, wherein the pouch is affixed to at least one of the first side wall and the second side wall of the carton form.

50. The package of claim 46, wherein the microwave energy interactive material comprises a layer of metal sufficiently thin to convert at least a portion of impinging microwave energy into thermal energy.

51. The package of claim 46, wherein

the microwave energy interactive material comprises a layer of metal,

the layer of metal is supported on a first polymer film,

a dimensionally stable substrate is joined to the layer of metal, and

a second polymer film is joined to the dimensionally stable substrate in a patterned configuration, thereby defining a plurality of closed cells between the second polymer film and the dimensionally stable substrate, wherein at least some of the closed cells inflate in response to microwave energy.

52. The carton of claim 51, wherein when the closed cells inflate in response to microwave energy, the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film.

53. The carton of claim 51, wherein when the closed cells inflate in response to microwave energy, the second polymer film bulges away from the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate.

54. A package for heating a food item in a microwave oven and comfortable handling thereafter, the package comprising:

a flexible pouch at least partially formed from a microwave energy interactive material, wherein the microwave energy interactive material increases in temperature in response to being exposed to microwave energy; and

a dimensionally stable carton at least partially joined to and receiving at least a portion of the sleeve, the carton including at least one area that is substantially transparent to microwave energy, wherein the transparent area remains substantially cool to the touch in response to being exposed to microwave energy.

55. The package of claim 54, wherein the microwave energy interactive material is supported on a polymer film.

56. The package of claim 54, wherein

the pouch comprises an insulating microwave packaging material including a plurality of closed cells that expand in response to exposure to microwave energy, and

the insulating microwave packaging material includes the microwave energy interactive material.

57. The package of claim 56, wherein the insulating microwave packaging material includes

a susceptor comprising the microwave energy interactive material supported on a first polymer film layer,

a moisture-containing layer joined to the microwave energy interactive material, and

a second polymer film layer joined to the moisture-containing layer in a predetermined pattern, thereby forming at least one closed cell between the moisture-containing layer and the second polymer film layer.

58. The package of claim 56, wherein the insulating microwave packaging material includes

the microwave energy interactive material supported on a first substantially vapor impermeable substrate,

a dimensionally stable substrate bonded to the microwave energy interactive material, and

a second substantially vapor impermeable substrate bonded to the dimensionally stable substrate along bond lines formed in a pattern, wherein the bond lines are substantially vapor impermeable, and the pattern defines a plurality of closed cells bounded by the second substantially vapor impermeable substrate, the dimensionally stable substrate, and the bond lines,

wherein upon impingement of the insulating microwave packaging material by microwave energy in a microwave oven, each of the plurality of closed cells expands to form an insulating pocket.

59. The package of claim 58, wherein

the insulating pocket comprises a bulging side and an opposing side,

the bulging side comprises a portion of each of the first substantially vapor impermeable substrate, the microwave energy interactive material, and the dimensionally stable substrate,

the opposing side comprises a portion of the second substantially vapor impermeable substrate, and

the bulging side lofts away from the opposing side.

60. The package of claim 58, wherein

the insulating pocket comprises a bulging side and an opposing side,

the bulging side comprises a portion of the second substantially vapor impermeable substrate,

the opposing side comprises a portion of each of the first substantially vapor impermeable substrate, the microwave energy interactive material, and the dimensionally stable substrate, and

the bulging side lofts away from the opposing side.

61. A microwave energy interactive insulating material comprising:

a layer of microwave energy interactive material supported on a first polymer film;

a dimensionally stable substrate joined to the layer of microwave energy interactive material; and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film,

wherein upon sufficient exposure to microwave energy,

at least some of the closed cells inflate, and

the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film.

62. The insulating material of claim 61, further comprising a paper layer joined to the first polymer film on a side of the first polymer film opposite the microwave energy interactive material.

63. The insulating material of claim 61, wherein the inflated cells are adapted to provide thermal insulation for at least one of a food item adjacent to the insulating material, and the layer of microwave interactive material.

64. The insulating material of claim 61, wherein the first polymer film and the second polymer film are each substantially vapor impermeable.

65. The insulating material of claim 61, wherein upon impingement of the insulating material by microwave energy, the microwave energy interactive layer generates sensible heat that heats and softens the first polymer film.

66. The insulating material of claim 65, wherein upon impingement of the insulating material by microwave energy,

the sensible heat further heats the second polymer film, and

the second polymer film contracts in at least one of an X direction and a Y direction.

67. The insulating material of claim 61, wherein when the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film, the second polymer film remains substantially flat.

68. The insulating material of claim 61, wherein upon impingement of the insulating material by microwave energy, a distance between the second polymer film and the dimensionally stable substrate in a center of at least one of the plurality of closed cells increases by at least an order of magnitude more than the distance before impingement by microwave energy.

69. The insulating material of claim 61, wherein upon impingement of the insulating material by microwave energy, a distance between the second polymer film and the dimensionally stable substrate in a center of at least one of the plurality of closed cells increases by up to 30 times more than the distance before impingement by microwave energy.

70. The insulating material of claim 61, wherein

the microwave energy interactive material comprises aluminum,

the dimensionally stable substrate comprises paper, paperboard, or any combination thereof, and

the second polymer film comprises biaxially-oriented polyester.

71. The insulating material of claim 61, wherein

the first polymer film and the second polymer film are each substantially vapor impermeable,

the second polymer film is joined to the dimensionally stable substrate with an adhesive in a patterned configuration, and

the adhesive penetrates the dimensionally stable substrate to form a substantially vapor impermeable barrier in conjunction with the first polymer film and the second polymer film.

72. The insulating material of claim 71, wherein the microwave energy interactive material is inactivated in a pattern corresponding to the patterned configuration of the adhesive.

73. The insulating material of claim 61, wherein the closed cells have a shape selected from the group consisting of 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.

74. The insulating material of claim 61, wherein the closed cells are substantially square in shape, substantially hexagonal in shape, or any combination thereof.

75. The insulating material of claim 61, wherein the closed cells are substantially elongate in shape.

76. A microwave packaging material comprising:

a susceptor film comprising a microwave energy interactive material supported on a first polymer film layer;

a moisture-containing layer joined to the microwave energy interactive material; and

a patterned adhesive layer joining a second polymer film to the moisture-containing layer, thereby defining at least one, closed cell between the moisture-containing layer and the second polymer film layer.

77. The microwave packaging material of claim 76, wherein the first polymer film layer comprises a biaxially-oriented polyester, the moisture-containing layer comprises a paper, and the second polymer film layer comprises a biaxially-oriented polyester.

78. The microwave packaging material of claim 76, wherein the closed cell expands when the microwave packaging material is exposed to microwave energy.

79. The microwave packaging material of claim 76, wherein the moisture-containing layer releases water vapor when the microwave packaging material is exposed to microwave energy.

80. The microwave packaging material of claim 76, wherein upon exposure to microwave energy, the moisture-containing layer releases water vapor, thereby inflating the closed cell.

81. A microwave packaging material consisting essentially of:

a first polymer film layer;

a microwave energy interactive material layer supported on the first polymer film;

a moisture-containing layer joined to the microwave energy interactive material layer;

a second polymer film layer; and

a patterned adhesive layer disposed between and joining the moisture-containing layer and the second polymer film layer, wherein the patterned adhesive layer defines a plurality of closed cells between the moisture-containing layer and the second polymer film.

82. The microwave packaging material of claim 81, wherein the moisture-containing layer releases water vapor when the microwave packaging material is exposed to microwave energy, thereby inflating at least some of the plurality of closed cells.

83. A microwave energy interactive structure comprising:

a first sheet and a second sheet of microwave energy interactive insulating material adjoined in a superposed, contacting relationship, wherein the microwave energy interactive insulating material includes

a layer of microwave energy interactive material supported on a first polymer film;

a dimensionally stable substrate joined to the layer of microwave energy interactive material; and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film, wherein at least some of the closed cells inflate upon sufficient exposure to microwave energy.

84. The structure of claim 83, wherein when the closed cells inflate, the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film.

85. The structure of claim 84, wherein when the closed cells inflate, the second polymer film remains substantially flat.

86. The structure of claim 84, wherein when the closed cells inflate, the second polymer contracts in at least one of an X direction and a Y direction, the X direction being substantially perpendicular to the Y direction.

87. The structure of claim 84, wherein the second polymer film comprises biaxially oriented polyester.

88. The structure of claim 83, wherein when the closed cells inflate, the second polymer film bulges away from the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate.

89. The structure of claim 88, wherein when the closed cells inflate, the first polymer film remains substantially flat.

90. The structure of claim 88, wherein the second polymer film comprises amorphous polyester.

91. The structure of claim 83, wherein the first sheet and the second sheet are joined such that the second polymer film of the first sheet is in a contacting relationship with the first polymer film of the second sheet.

92. The structure of claim 83, wherein the first sheet and the second sheet are joined such that the second polymer film of the first sheet is in a contacting relationship with the second polymer film of the second sheet.

93. The structure of claim 83, wherein the first sheet and the second sheet are joined such that the first polymer film of the first sheet is in a contacting relationship with the first polymer film of the second sheet.

94. The structure of claim 83, wherein the first sheet and the second sheet are joined along a plurality of points proximate a perimeter of each the first sheet and the second sheet.

95. The structure of claim 83, wherein the first sheet and the second sheet are joined substantially continuously to one another.

96. The structure of claim 95, wherein the first sheet and the second sheet are joined substantially continuously to one another using a substantially continuous layer of adhesive.

97. A microwave energy interactive insulating package comprising a plurality of adjoined panels that define a cavity for receiving a food item,

wherein at least one panel of the plurality of adjoined panels comprises an microwave energy interactive insulating material including

a layer of microwave energy interactive material supported on a first polymer film,

a dimensionally stable substrate joined to the layer of microwave energy interactive material, and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film, and

wherein upon sufficient exposure to microwave energy,

at least some of the closed cells inflate, and

the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge toward the cavity.

98. The package of claim 97, further comprising an interior surface at least partially defined by the first polymer film.

99. The package of claim 97, wherein the plurality of adjoined panels includes a first panel and a second panel in an opposed, facing relationship with the cavity therebetween.

100. The package of claim 99, wherein

the first panel and the second panel each comprise the insulating material, and

the package further comprises an interior surface at least partially defined by the first polymer layer of the first panel and the first polymer layer of the second panel.

101. The package of claim 99, further comprising a third panel joined to the second panel in a facing relationship, wherein the third panel comprises the microwave energy interactive insulating material.

102. A microwavable food carton comprising:

an interior surface; and

a sheet of microwave energy interactive insulating material joined to at least a portion of the interior surface,

wherein the microwave energy interactive insulating material includes

a layer of microwave energy interactive material supported on a first polymer film,

a dimensionally stable substrate joined to the layer of microwave energy interactive material, and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film, wherein at least some of the closed cells inflate in response to microwave energy.

103. The carton of claim 102, wherein when the closed cells inflate in response to microwave energy, the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate bulge away from the second polymer film.

104. The carton of claim 102, wherein when the closed cells inflate in response to microwave energy, the second polymer film bulges away from the first polymer film, the layer of microwave energy interactive material, and the dimensionally stable substrate.

105. The carton of claim 102, wherein

the sheet includes a perimeter, and

the sheet includes at least one slit adjacent to the perimeter, the slit being adapted to allow the sheet to expand or contract in response to microwave energy.

106. A microwave energy interactive insulating material comprising:

a layer of microwave energy interactive material supported on a first polymer film;

a dimensionally stable substrate joined to the layer of microwave energy interactive material; and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film,

wherein upon sufficient exposure to microwave energy,

at least some of the closed cells inflate, and

the second polymer film bulges away from the dimensionally stable substrate, the layer of microwave energy interactive material, and the first polymer film.

107. The insulating material of claim 106, further comprising a paper layer joined to the first polymer film on a side of the first polymer film opposite the microwave energy interactive material.

108. The insulating material of claim 106, wherein the first polymer film and the second polymer film are each substantially vapor impermeable.

109. The insulating material of claim 106, wherein the second polymer film is joined to the dimensionally stable substrate in a patterned configuration by selectively heating a portion the second polymer film in the patterned configuration.

110. The insulating material of claim 106, wherein the portion of the second polymer film that is selectively heated penetrates the dimensionally stable substrate to form a substantially vapor impermeable barrier in conjunction with the first polymer film and the second polymer film.

111. The insulating material of claim 106, wherein upon impingement of the microwave energy interactive material by microwave energy, the microwave energy interactive layer generates sensible heat that heats and softens the second polymer film.

112. The insulating material of claim 106, wherein when the closed cells inflate,

the softened second polymer film bulges away from the first polymer film, and

the first polymer film remains substantially flat.

113. The insulating material of claim 106, wherein upon impingement of the insulating material by microwave energy, a distance between the second polymer film and the dimensionally stable substrate in a center of at least one of the plurality of closed cells increases by at least an order of magnitude more than the distance before such impingement.

114. The insulating material of claim 106, wherein upon impingement of the insulating material by microwave energy, a distance between the second polymer film and the dimensionally stable substrate in a center of at least one of the plurality of closed cells increases by up to 30 times more than the distance before such impingement.

115. The insulating material of claim 106, wherein the inflated cells reduce heat loss from at least one of

a food item adjacent to the insulating material, and

the layer of microwave interactive material.

116. The insulating material of claim 106, wherein

the dimensionally stable substrate comprises a paper, paperboard, or any combination thereof, and

the second polymer film comprises amorphous polyester.

117. A microwave energy interactive package comprising an outer surface at least covered by a microwave energy interactive insulating material including:

a layer of microwave energy interactive material supported on a first polymer film;

a dimensionally stable substrate joined to the layer of microwave energy interactive material; and

a second polymer film joined to the dimensionally stable substrate in a patterned configuration that defines a plurality of closed cells between the dimensionally stable substrate and the second polymer film,

wherein upon sufficient exposure to microwave energy,

at least some of the closed cells inflate, and

the second polymer film bulges away from the dimensionally stable substrate, the layer of microwave energy interactive material, and the first polymer film.

118. The package of claim 117, comprising an outer surface at least partially defined by the second polymer film.

119. The package of claim 118, wherein when the closed cells inflate, the outer surface remains cool to the touch.

120. The package of claim 117, comprising a plurality of adjoined panels, at least one panel including an exterior surface at least partially defined by the second polymer film.

121. The package of claim 120, wherein the closed cells inflate, the outer surface remains cool to the touch.

122. The package of claim 117, wherein the second polymer film is joined to the dimensionally stable substrate in a patterned configuration by selectively heating a portion the second polymer film in the patterned configuration.

123. The package of claim 117, wherein the portion of the second polymer film that is selectively heated penetrates the dimensionally stable substrate to form a substantially vapor impermeable barrier in conjunction with the first polymer film and the second polymer film.

124. The package of claim 117, wherein upon impingement of the microwave energy interactive material by microwave energy, the microwave energy interactive layer generates sensible heat that heats and softens the second polymer film.

125. The insulating material of claim 117, wherein when the closed cells inflate,

the softened second polymer film bulges away from the first polymer film, and

the first polymer film remains substantially flat.

126. The insulating material of claim 117, wherein

the dimensionally stable substrate comprises a paper, paperboard, or any combination thereof, and

the second polymer film comprises amorphous polyester.

127. A package for heating a food item in a microwave oven and comfortable handling thereafter, the package comprising:

an insulating microwave packaging material including a plurality of expandable closed cells, the insulating microwave packaging material including at least one area that is microwave energy active and at least one area that is microwave energy inactivated,

wherein the microwave energy active area increases in temperature upon exposure to microwave energy, and

wherein the microwave energy inactivated area remains substantially cool to the touch upon exposure to microwave energy.

128. The package of claim 127, wherein the insulating microwave packaging material includes

a susceptor film comprising a microwave energy interactive material supported on a first polymeric film layer, wherein the microwave energy interactive material is inactivated in the microwave energy inactivated area,

a moisture-containing layer superposed with the microwave energy interactive material, and

a second polymeric film layer joined to the moisture-containing layer in a predetermined pattern, thereby forming at least one closed cell of the expandable cells between the moisture-containing layer and the second polymeric film layer.

129. The package of claim 127, wherein the insulating microwave packaging material includes

a first substantially vapor impermeable substrate,

a layer of microwave energy interactive material supported by the first substantially vapor impermeable substrate, wherein the microwave energy interactive material is inactivated in the microwave energy inactivated area,

a dimensionally stable substrate bonded to the layer of microwave interactive material, and

a second substantially vapor impermeable substrate bonded to the dimensionally stable substrate along bond lines formed in a pattern, wherein the bond lines are substantially vapor impermeable, and the pattern defines a plurality of closed cells bounded by the second substantially vapor impermeable substrate, the dimensionally stable substrate, and the bond lines,

wherein upon impingement of the insulating microwave packaging material by microwave energy in a microwave oven, each of the plurality of closed cells expands to form an insulating pocket.

130. The package of claim 129, wherein

the insulating pocket includes a bulging side and an opposing side,

the bulging side comprises a portion of each of the first substantially vapor impermeable substrate, the microwave energy interactive material layer, and the dimensionally stable substrate,

the opposing side comprises a portion of the second substantially vapor impermeable substrate, and

the bulging side lofts away from the opposing side.

131. The package of claim 129, wherein

the insulating pocket comprises a bulging side and an opposing side,

the bulging side comprises a portion of the second substantially vapor impermeable substrate,

the opposing side comprises a portion of each of the first substantially vapor impermeable substrate, the microwave energy interactive material layer, and the dimensionally stable substrate, and

the bulging side lofts away from the opposing side.