US4190757A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave heating package and method
Assignee: Pillsbury Co
•
Filing: 1978-01-19
•
Granted: 1980-02-26
•
Expires: 1998-01-19
Abstract
Abstract The invention provides a distribution and heating method for foodstuffs and an inexpensive disposable microwave shipping, heating and serving package for food composed of a paperboard carton and a lossy microwave energy absorber which becomes hot when exposed to microwave radiation. The absorber is associated in conductive heat transfer relationship with a food product contained in the package and is usually bonded to a structural supporting sheet such as aluminum foil. The package also includes a shield e.g., a metal foil sheet adapted to reduce by a controlled amount the direct transmission of microwave energy into the food product. The shield may have holes of a selected size to provide a predetermined controlled amount of direct microwave energy to the food product or can be a nonperforated sheet or screen. The absorber heats the adjacent surface of the food by conduction to a sufficiently high temperature to provide searing or browning while controlled microwave exposure heats the inside. The thickness of the absorber is substantially in the range wherein absorber thickness and temperature response are positively correlated.
Inventors
- 👤 Charles H. Turpin
- 👤 Thomas C. Hoese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:42
CPC Classifications
B; B65; B65D; B65D81/00; B65D81/34; B65D81/3446; B65D2581/00; B65D2581/34; B65D2581/3401; B65D2581/3402; B65D2581/3405; B65D2581/3406; B65D2581/3437; B65D2581/3439; B65D2581/3447; B65D2581/3448; B65D2581/3463; B65D2581/3464; B65D2581/3471; B65D2581/3472; B65D2581/3477; B65D2581/3479; B65D2581/3481; B65D2581/3482; B65D2581/3486; B65D2581/3489; B65D2581/3494
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
194 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave absorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being at least about 0.016 inch thick and being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, said sheet being of the minimum thickness that will reach but not exceed a preselected equilibrium operating temperature, a metal sheet in overlying relation to one side of and adjacent to the heating body, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 2
Dependent Claim
194 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave absorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being at least about 0.016 inch thick and being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, said sheet being of the minimum thickness that will reach but not exceed a preselected equilibrium operating temperature, a metal sheet in overlying relation to one side of and adjacent to the heating body, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 3
Dependent Claim
202 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave adsorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, said sheet being of a paint-like layer applied to a metal support structure in sheet form and being bonded thereto on at least one surface thereof, the paint-like layer of adsorptive material being on the order of about 0.016" thick or more and said sheet and support structure being flexible, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 4
Dependent Claim
202 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave adsorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, said sheet being of a paint-like layer applied to a metal support structure in sheet form and being bonded thereto on at least one surface thereof, the paint-like layer of adsorptive material being on the order of about 0.016" thick or more and said sheet and support structure being flexible, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 5
Dependent Claim
198 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave absorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being at least about 0.016" thick and being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, the heating body comprising a multiplicity of particles of microwave absorptive material of different particle sizes and a binder bonding said particles together, a metal sheet in overlying relation to one side of and adjacent to the heating body, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 6
Dependent Claim
198 words
A food heating package adapted to contain a food product comprising a package body formed from microwave transparent non-lossy dielectric sheet material having a cellulosic or plastic resinous base defining a container body and a lossy microwave absorptive heating body connected to the package and associated in heat conductive relationship with said food, said heating body being in sheet form and the thickness of said sheet being at least about 0.016" thick and being substantially within the range wherein the sheet thickness and the temperature response during microwave heating are positively correlated, the heating body comprising a multiplicity of particles of microwave absorptive material of different particle sizes and a binder bonding said particles together, a metal sheet in overlying relation to one side of and adjacent to the heating body, said heating body being characterized by heating when exposed to microwave radiation within a microwave oven to a sufficient temperature to sear, brown or crisp the food and cooling in 30 seconds or less after the oven is turned off to the temperature of the food whereby the package can be used as a dish from which the food can be directly eaten without burning the fingers.
Claim 7
Dependent Claim
23 words
The package of claim 3 wherein at least some of the microwave absorptive particles are iron oxide and the binder is a mineral.
Claim 8
Dependent Claim
21 words
The package of claim 3 wherein the microwave absorptive material comprises Fe 3 O 4 and said binder is sodium silicate.
Claim 9
Dependent Claim
21 words
The package of claim 5 wherein a microwave transparent mineral is mixed with the Fe 3 O 4 as a diluent.
Claim 10
Dependent Claim
19 words
The package of claim 3 wherein the heating body is between about 0.016 and about 0.187 inches in thickness.
Claim 11
Dependent Claim
24 words
The food heating package of claim 4 wherein a microwave transparent material in solid particulate form is mixed with the particles of iron oxide.
Claim 12
Dependent Claim
26 words
The package of claim 3 wherein the microwave absorber sheet is of the minimum thickness that will reach but not exceed a preselected equilibrium operating temperature.
Claim 13
Dependent Claim
195 words
A disposable microwave food heating package adapted to contain a food product comprising an outer container body formed from paperboard, a lossy microwave absorptive heating element comprising a composite sheet mounted within the container, said composite sheet comprising an upper layer of a metal foil and a lower paint-like layer comprising a microwave absorptive substance in particulate form and a binder bonding the particles together and maintaining the absorptive layer in contact with the metal sheet, said paint-like layer being at least about 0.016" thick and being substantially within the range wherein the layer thickness and the temperature response during microwave heating are positively correlated, said container body having a top wall and a microwave opaque shield member comprising an electrically conductive metal sheet bonded to the top wall, said shield at least partially surrounding when the food is placed within the package to provide a predetermined controlled amount of direct microwave energy transmission into the food in an amount less than that which would be received by the food without the shield, whereby the food is simultaneously heated by the dual effect of controlled microwave radiation heating and by conduction from the composite sheet.
Claim 14
Dependent Claim
195 words
A disposable microwave food heating package adapted to contain a food product comprising an outer container body formed from paperboard, a lossy microwave absorptive heating element comprising a composite sheet mounted within the container, said composite sheet comprising an upper layer of a metal foil and a lower paint-like layer comprising a microwave absorptive substance in particulate form and a binder bonding the particles together and maintaining the absorptive layer in contact with the metal sheet, said paint-like layer being at least about 0.016" thick and being substantially within the range wherein the layer thickness and the temperature response during microwave heating are positively correlated, said container body having a top wall and a microwave opaque shield member comprising an electrically conductive metal sheet bonded to the top wall, said shield at least partially surrounding when the food is placed within the package to provide a predetermined controlled amount of direct microwave energy transmission into the food in an amount less than that which would be received by the food without the shield, whereby the food is simultaneously heated by the dual effect of controlled microwave radiation heating and by conduction from the composite sheet.
Claim 15
Dependent Claim
36 words
The package of claim 10 wherein the absorptive substance comprises Fe 3 O 4 in particulate form and an inert mineral filler and said paint-like layer is between about 0.02 inch to 0.187 inch in thickness.
Claim 16
Dependent Claim
26 words
The package according to claim 10 wherein the lossy substance comprises Fe 3 O 4 with an inert mineral filler and the binder comprises sodium silicate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-02-25 | 1983-08-27 | 1984-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-02-25 | 1987-08-27 | 1988-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-02-25 | 1991-08-27 | 1992-02-26 | $7700.00 | Window Closed / Lapsed |