Patent ID: 8440275

Claim:
An insulating microwave material comprising: a dimensionally stable substrate having a first side and a second side; a susceptor film joined to the first side of the dimensionally stable substrate by a substantially continuous layer of adhesive, the susceptor film comprising microwave energy interactive material supported on a first polymer film, wherein the susceptor film is joined to the first side of the dimensionally stable substrate so that the microwave energy interactive material is disposed between the first polymer film and the first side of the dimensionally stable substrate; and a second polymer film at least partially covered by a layer of amorphous polyethylene terephthalate so that the layer of amorphous polyethylene terephthalate is in direct contact with the second polymer film, wherein the layer of amorphous polyethylene terephthalate is directly bonded in a patterned configuration to the second side of the dimensionally stable substrate to define a plurality of closed cells directly between the second side of the dimensionally stable substrate and the layer of amorphous polyethylene terephthalate, so that the closed cells are bounded by the second side of the dimensionally stable substrate and the layer of amorphous polyethylene terephthalate, wherein the closed cells are operative for inflating in response to microwave energy.