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US 4,518,651 AGranted
Microwave absorber
AssigneeE. I. Du Pont de Nemours and Company
InventorWilliam R. Wolfe, Jr.
Life of this patent
Estimating the term…
Abstract
A flexible composite material is disclosed which exhibits a controlled absorption of microwave energy based on presence of particulate carbon in a polymeric matrix bound to a porous substrate. The material is used in packages for microwave cooking. A process for making the material is also disclosed.
Claims8
A composite material for generation of heat by absorption of microwve energy comprising:
- (a) a porous, dielectric, substrate substantially transparent to microwave radiation;
- (b) an electrically conductive coating on one surface of the substrate comprising;
- (i) electrically conductive particles in
- (ii) a thermoplastic dielectric matrix, wherein, at least some of the matrix is beneath the surface of the substrate, is substantially free of electrically conductive particles, and is intermingled with the substrate;
- and
- (c) a protective layer of polyethylene terephthalate adhered to the electrically conductive coating.
3 more elements
A composite material for generation of heat by absorption of microwave energy comprising:
- (a) a porous, dielectric paperboard substrate substantially transparent to microwave radiation;
- (b) a coating on one surface of the substrate comprising:
- (i) 25 to 60 weight percent finely-divided carbon particles in
- (ii) 40 to 75 weight percent thermoplastic dielectric matrix,
- wherein at least some of the matrix is beneath the surface of the substrate, is substantially free of carbon particles, and is intermingled with the substrate;
- and
- (c) a protective layer of polyethylene terephthalate adhered to the coating.
4 more elements
A process for manufacturing a composite material generation of heat by absorption of microwave energy comprising:
- (a) providing a porous, dielectric, substrate substantially transparent to microwave radiation;
- (b) applying to the substrate a coating of a dispersion of finely-divided, electrically conductive, particles in a thermoplastic dielectric matrix;
- (c) heating the coating and the substrate to a temperature above the softening point of the matrix;
- and
- (d) pressing the heated coating against the substrate at a pressure of 600 to 8700 kilopascals for 0.03 to 200 seconds.
2 more elements
Dependencies are inferred from the claim text.