US5410135A — Self limiting microwave heaters

Claim 1

Independent Claim 139 words

A self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature from about 300° F. to about 480° F. and said dispersion being near the percolation threshold so that its electrical conductivity drops at least about 1.5 orders of magnitude when above the binder phase transition temperature wherein said conductive material combined with said binder has a surface resistivity ranging from about 25 ohms per square to about 100,000 ohms per square at room temperature.

Claim 2

Dependent Claim 139 words

A self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature from about 300° F. to about 480° F. and said dispersion being near the percolation threshold so that its electrical conductivity drops at least about 1.5 orders of magnitude when above the binder phase transition temperature wherein said conductive material combined with said binder has a surface resistivity ranging from about 25 ohms per square to about 100,000 ohms per square at room temperature.

Claim 3

Dependent Claim 34 words

The dispersion of claim 1 wherein said conductive material combined with said binder will have a surface resistivity ranging from about 100 ohms per square to about 50,000 ohms per square at room temperature.

Claim 4

Dependent Claim 95 words

The dispersion of claim 1 wherein said conductive material consists essentially of carbon black or graphite having a nitrogen surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation.

Claim 5

Dependent Claim 21 words

The dispersion of claim 3 wherein said binder consists essentially of a polycarbonate, methylpentene copolymer, polyvinyl alcohol or a cellulose ester.

Claim 6

Dependent Claim 19 words

The dispersion of claim 3 wherein said self-limiting temperature range is from about 300° F. to about 450° F.

Claim 7

Dependent Claim 19 words

The dispersion of claim 3 wherein said self-limiting temperature range is from about 350° F. to about 400° F.

Claim 8

Dependent Claim 22 words

The dispersion of claim 3 wherein said conductive material is present in an amount from about 15 to about 40% by weight.

Claim 9

Dependent Claim 14 words

The dispersion of claim 7 wherein said conductive material consists essentially of carbon black.

Claim 10

Dependent Claim 13 words

The dispersion of claim 8 wherein said binder consists essentially of a polycarbonate.

Claim 11

Dependent Claim 14 words

The dispersion of claim 9 wherein said polycarbonate consists essentially of a polyphthalate carbonate.

Claim 12

Dependent Claim 40 words

The dispersion of claim 9 wherein said polycarbonate has a Vicat softening point of from about 305° F. to about 315° F. and said microwave heater has a self-limiting temperature range of from about 300° F. to about 350° F.

Claim 13

Dependent Claim 35 words

The dispersion of claim 9 wherein said polycarbonate has a Vicat softening point of from about 320° F. to about 400° F. and a self-limiting temperature range from about 325° F. to about 450° F.

Claim 14

Dependent Claim 14 words

The dispersion of claim 8 wherein said binder consists essentially of a methylpentene copolymer.

Claim 15

Dependent Claim 14 words

The dispersion of claim 8 wherein said binder consists essentially of a polyvinyl alcohol.

Claim 16

Dependent Claim 14 words

The dispersion of claim 8 wherein said binder consists essentially of a cellulose ester.

Claim 17

Dependent Claim 17 words

The dispersion of claim 1 wherein said dispersion is a extrusion composition or solvent cast film composition.

Claim 18

Dependent Claim 13 words

The dispersion of claim 1 wherein said dispersion is a surface coating composition.

Claim 19

Dependent Claim 14 words

The dispersion of claim 17 wherein said dispersion is a liquid surface coating composition.

Claim 20

Dependent Claim 197 words

An article of manufacture comprising a self-limiting microwave heater wherein said heater comprises a film of a self-limiting dispersion of a conductive material in a binder, where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said dispersion being near the percolation threshold so that its electrical conductivity drops at least about 1.5 orders of magnitude when above the binder phase transition temperature, wherein said conductive material consists essentially of carbon black or graphite having a nitrogen absorption surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation, said film being from about 0.1 mils to about 10 mils thick.

Claim 21

Dependent Claim 197 words

An article of manufacture comprising a self-limiting microwave heater wherein said heater comprises a film of a self-limiting dispersion of a conductive material in a binder, where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said dispersion being near the percolation threshold so that its electrical conductivity drops at least about 1.5 orders of magnitude when above the binder phase transition temperature, wherein said conductive material consists essentially of carbon black or graphite having a nitrogen absorption surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation, said film being from about 0.1 mils to about 10 mils thick.

Claim 22

Dependent Claim 23 words

The article of manufacture of claim 19 wherein said dispersion is a thermoplastic solid applied to a microwave transparent substrate by extrusion coating.

Claim 23

Dependent Claim 26 words

The article of manufacture of claim 19 wherein said dispersion is in the form of a thermoplastic film applied to a microwave transparent substrate by lamination.

Claim 24

Dependent Claim 21 words

The article of manufacture of claim 19 wherein said film is applied to a microwave transparent substrate by coating or printing.

Claim 25

Dependent Claim 153 words

An article of manufacture for heating food by microwave energy comprising a self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature from about 300° F. to about 480° F., said dispersion being near the percolation threshold so that its electrical conductivity drops at least from about 1.5 to about 2 orders of magnitude when above the binder phase transition temperature, wherein said conductive material combined with said binder has a surface resistivity ranging from about 25 ohms per square to about 100,000 ohms per square at room temperature.

Claim 26

Dependent Claim 153 words

An article of manufacture for heating food by microwave energy comprising a self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature from about 300° F. to about 480° F., said dispersion being near the percolation threshold so that its electrical conductivity drops at least from about 1.5 to about 2 orders of magnitude when above the binder phase transition temperature, wherein said conductive material combined with said binder has a surface resistivity ranging from about 25 ohms per square to about 100,000 ohms per square at room temperature.

Claim 27

Dependent Claim 33 words

The article of manufacture of claim 23 wherein said conductive material combined with said binder will have a surface resistivity ranging from about 100 ohms per square to about 50,000 ohms per square.

Claim 28

Dependent Claim 97 words

The article of manufacture of claim 23 wherein said conductive material consists essentially of carbon black or graphite having a nitrogen surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation.

Claim 29

Dependent Claim 15 words

The article of manufacture of claim 25 wherein said conductive material is said carbon black.

Claim 30

Dependent Claim 23 words

The article of manufacture of claim 26 wherein said binder consists essentially of a polycarbonate, methylpentene copolymer, polyvinyl alcohol or a cellulose ester.

Claim 31

Dependent Claim 21 words

The article of manufacture as in claims 25, 26 or 27 where said dispersion is applied in patterns on said substrate.

Claim 32

Dependent Claim 23 words

The article of manufacture as in claims 25, 26 or 27 where said dispersion is applied in different coating thicknesses on said substrate.

Claim 33

Dependent Claim 22 words

The article of manufacture of claim 26 wherein said dispersion is a film from about 0.1 mils to about 10 mils thick.

Claim 34

Dependent Claim 18 words

The article of manufacture of claim 30 wherein said dispersion is operatively associated with a microwave transparent substrate.

Claim 35

Dependent Claim 23 words

The article of manufacture of claim 31 wherein said dispersion is a thermoplastic solid applied to a microwave transparent substrate by extrusion coating.

Claim 36

Dependent Claim 26 words

The article of manufacture of claim 31 wherein said dispersion is in the form of a thermoplastic film applied to a microwave transparent substrate by lamination.

Claim 37

Dependent Claim 21 words

The article of manufacture of claims 31 wherein said dispersion is applied to a microwave transparent substrate by coating or printing.

Claim 38

Dependent Claim 17 words

The article of manufacture as in claims 31, 32, 33 or 34 where said substrate is paper.

Claim 39

Dependent Claim 17 words

The article of manufacture as in claims 31, 32, 33 or 34 where said substrate is paperboard.

Claim 40

Dependent Claim 18 words

The article of manufacture as in claims 31, 32, 33 or 34 where said substrate is a thermoplastic

Claim 41

Dependent Claim 17 words

The article of manufacture as in claims 31, 32, 33 or 34 where said substrate is glass.

Claim 42

Dependent Claim 18 words

The article of manufacture as in claims 31, 32, 33 or 34 where said substrate is a ceramic.

Claim 43

Dependent Claim 21 words

The article of manufacture of claim 25 wherein said self-limiting temperature range is from about 300° F. to about 450° F.

Claim 44

Dependent Claim 21 words

The article of manufacture of claim 25 wherein said self-limiting temperature range is from about 350° F. to about 400° F.

Claim 45

Independent Claim 194 words

A method of heating food comprising applying microwave energy to an article of manufacture where said article of manufacture comprises a self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, wherein said conductive material consists essentially of carbon black or graphite having a nitrogen absorption surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 46

Independent Claim 194 words

A method of heating food comprising applying microwave energy to an article of manufacture where said article of manufacture comprises a self-limiting dispersion of a conductive material in a binder where said conductive material consists essentially of a carbon material having a structure selected to have a percolation threshold when dispersed in said binder at a concentration of from about 10 weight percent to about 45 weight percent in said binder, wherein said conductive material consists essentially of carbon black or graphite having a nitrogen absorption surface area of from about 5 to about 160 m 2 /g, a DBP absorption number of from about 30 to about 150 cc/100 gm, and an average particle diameter of from about 15 to about 100 nm, said binder comprising a thermoplastic material selected to go through a first order phase transition or a second order phase transition at a temperature of from about 300° F. to about 480° F. when exposed to microwave radiation, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 47

Dependent Claim 57 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said conductive material is carbon black, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 48

Dependent Claim 58 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture, wherein said binder consists essentially of a polycarbonate, methylpentene copolymer, polyvinyl alcohol or a cellulose ester, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture.

Claim 49

Dependent Claim 68 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture, said article of manufacture having a self-limiting temperature range of from about 300° F. to about 450° F., said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 450° F.

Claim 50

Dependent Claim 69 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture of said article of manufacture having a self-limiting temperature range of from about 350° F. to about 400° F. said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 350° F. to about 400° F.

Claim 51

Dependent Claim 63 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said dispersion is from about 0.1 mils to about 10 mils thick, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 52

Dependent Claim 61 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said dispersion is operatively associated with a microwave transparent substrate, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 53

Dependent Claim 65 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said dispersion is a solid applied to a microwave transparent substrate by extrusion coating, said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 54

Dependent Claim 68 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said dispersion is in the form of a film applied to a microwave transparent substrate by lamination said food being operatively associated with said article of manufacture, said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 55

Dependent Claim 65 words

A method of heating food according to claim 42 comprising applying microwave energy to said article of manufacture wherein said dispersion is applied to a microwave transparent substrate by coating or printing, said food being operatively associated with said article of manufacture, and said microwave energy being sufficient to raise the temperature of said article of manufacture from about 300° F. to about 480° F.

Claim 56

Dependent Claim 84 words

The carbon blacks as in claims 3, 5, 8, 9, 10, 25, 27, 31, 42, 44, or 54, comprising large particle size carbon blacks having a particle size from about 40 nm to about 90 nm blended with small particle size carbon blacks having a particle size from about 20 nm to about 35 nm, the ratio of said large particle size carbon blacks to said small particle size carbon blacks being from about 80/20 percent by weight to about 60/40 percent by weight.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-04-24	1998-10-24	1999-04-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-04-24	2002-10-24	2003-04-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-04-24	2006-10-24	2007-04-25	$7700.00	Window Closed / Lapsed

Self limiting microwave heaters

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