Microwaveable container

Patent metadata

Field	Value
Publication number	US-10244586-B2
Application number	US-201615223132-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jul 29, 2016
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A microwaveable container comprising a pan and a pan cover, the pan comprising a bottom, a continuous wall, a rim, a first heating layer and a first polymeric layer; the pan cover comprising an upper surface, a lower surface, an outer side edge, a second polymeric layer, and a second heating layer, the first heating layer being attached to the pan bottom, the second heating layer being attached to the pan cover, and wherein the first polymeric layer is attached to the rim, the first heating layer and the pan bottom, the second polymeric layer being attached to the pan cover and the second heating layer; the first and second heating layers independently comprising: a susceptor powder selected from manganese zinc ferrite, nickel zinc ferrite, strontium ferrite or mixtures thereof; and a polymer matrix selected from a silicone rubber, a liquid crystal polymer, a polyphenylene sulfide polymer or mixtures thereof.

First claim

We claim:

1. A microwaveable container comprising a pan and a pan cover,
the pan comprising a bottom, a continuous wall, a rim, and a first polymeric layer,
the bottom comprising an upper surface and a lower surface,
the continuous wall projecting upwardly along the periphery of the bottom, and comprising a top, a base, an inner surface and an outer surface,
the rim extending outwardly from the top of the continuous wall, and comprising a top surface, a bottom surface, and an outer side edge, and
the first polymeric layer being attached to the rim top surface, the outer side edge of the rim, and the lower surface of the pan bottom; and

the pan cover comprising an upper surface, a lower surface, an outer side edge, and a second polymeric layer, wherein the pan cover fits within and is slidable vertically up and down within the continuous wall of the pan for contact between the lower surface of the pan cover with food,
the second polymeric layer is attached to the pan cover upper surface and the pan cover side edge,
and wherein both of said pan and said pan cover further includes a heating layer, the heating layer associated with said pan being a first heating layer and the heating layer associated with said pan cover being a second heating layer,
the first heating layer comprising an upper surface and a lower surface, the upper surface of the first heating layer being attached to the lower surface of the bottom of said pan and the lower surface being attached to the first polymeric layer,
the second heating layer comprising an upper surface and a lower surface, the lower surface of the second heating layer being attached to the upper surface of the pan cover and the upper surface being attached to the second polymeric layer.

2. The container of claim 1 wherein each said heating layer independently comprising:
a susceptor powder selected from manganese zinc ferrite, nickel zinc ferrite, strontium ferrite or mixtures thereof; and
a polymer matrix selected from a silicone rubber, a liquid crystal polymer, a polyphenylene sulfide polymer or mixtures thereof,
the susceptor powder being dispersed in the polymer matrix.

3. The container of claim 2 wherein each said heating layer comprises 15 to 85 wt % of the susceptor powder and 85 to 15 wt % of the polymer based on the total weight of the heating layer.

4. The container of claim 3 wherein each said heating layer comprises 70 to 80 wt % of the susceptor powder and 30 to 20 wt % of the polymer based on the total weight of the heating layer.

5. The container of claim 3 wherein the susceptor powder has an average particle diameter from 1 to 500 microns.

6. The container of claim 3 wherein the average particle diameter of the susceptor powder is from 1 to 13 microns.

7. The container of claim 3 wherein the susceptor powder has a Curie Temperature from higher than 175° C. to lower than 260° C.

8. The container of claim 7 wherein the Curie Temperature of the susceptor powder is from 190° C. to 240° C.

9. The container of claim 8 wherein the Curie Temperature of the susceptor powder is from 204° C. to 221° C.

10. The container of claim 3 wherein the susceptor powder is sintered.

11. The container of claim 3 wherein the susceptor is a manganese zinc ferrite.

12. The container of claim 11 wherein the manganese zinc ferrite comprises 5.0 to 27.0 wt % of Mn 3 O 4 ; 4.0 to 25.0 wt % ZnO; and 40.0 to 80.0 wt % of Fe 2 O 3 , based on the total weight of the manganese zinc ferrite.

13. The container of claim 12 wherein the manganese zinc ferrite comprises 18.0 to 27.0 wt % of Mn 3 O 4 ; 8.0 to 15.0 wt % ZnO; and 40.0 to 70.0 wt % of Fe 2 O 3 , based on the total weight of the manganese zinc ferrite.

14. The container of claim 1 wherein the polymer matrix is a silicone rubber.

15. The container of claim 14 wherein the silicone rubber is selected from a liquid silicone rubber or a high consistency rubber.

16. The container of claim 15 wherein the liquid silicone rubber or high-consistency rubber have repeating units of Si—O—Si of the general formula:

wherein
the liquid silicone rubber has a molecular weight of 900 to 7,600, and a degree of polymerization of 10 to 100,
the high consistency rubber has a molecular weight of 370,000 to 740,000 and a degree of polymerization of 5,000 to 10,000,

the degree of polymerization is the sum of x and y, and R is selected from OH, —CH 3 , —CH═CH 2 , or aryl groups.

17. A process for fabricating a microwaveable container, the process comprising:
deep-drawing a first metal blank to form an unfinished pan comprising a bottom, a continuous wall, and a rim;
the bottom comprising an upper surface and a lower surface,
the continuous wall projecting upwardly along the periphery of the bottom, and comprising a top, a base, an inner surface and an outer surface,
the rim extending outwardly from the top of the continuous wall, and comprising a top surface, a bottom surface, and an outer edge,

deep-drawing a second metal blank to form an unfinished pan cover, the pan cover comprising an upper surface, a lower surface, and an outer side edge;
piercing the rim to form a plurality of perforations in the rim of the unfinished pan;
applying a nonstick coating to the pan bottom upper surface, continuous wall inner surface and pan cover lower surface;
over-molding a heating layer comprising a susceptor powder dispersed in a polymer matrix onto both of
the pan bottom lower surface, and
the pan cover upper surface,

over-molding a polymeric layer onto the pan bottom lower surface and pan rim, wherein the outer surface of the continuous wall is bare metal,
over-molding a polymeric layer onto the entire upper surface of the pan cover and just the outside periphery of the lower surface of the pan cover.

18. The process of claim 17 further comprising applying a primer to the pan bottom lower surface prior to over-molding with the heating layer.

19. The process of claim 17 further comprising applying a primer to the pan cover upper surface prior to over molding with the heating layer.

20. A microwaveable container comprising:
a pan comprising:
a first metal layer defining a pan bottom having an upper surface which contacts food and a continuous wall extending upwardly from the pan bottom, thereby defining a cavity for receiving food;
a first heating layer having an upper surface and an opposing lower surface, the upper surface is attached to a surface of the first metal layer opposite the upper surface which contacts food; and
a first polymeric layer covering the lower surface of the first heating layer and in contact with the first metal layer; and

a pan cover comprising:
a second metal layer defining a cover bottom having a lower surface which contacts food;
a second heating layer having an upper surface and an opposing lower surface, the lower surface is attached to a surface of the second metal layer opposite the lower surface which contacts food; and
a second polymeric layer covering the upper surface of the second heating layer and in contact with the second metal layer;

wherein the pan cover fits within the cavity of the pan and is slidable vertically up and down within the cavity for contact between the lower surface of the second metal layer and food.

21. The container of claim 20 , wherein the pan cover defines a vent gap between a side edge of the pan cover a

Assignees

• Dart Ind Inc

Inventors

• Barea Hector J
• Terrill Jr Mark T
• Luo Jianjun

Classifications

• B29C45/1671

  with an insert · CPC title

• B21D51/18

  vessels, e.g. tubs, vats, tanks, sinks, or the like · CPC title

• C04B35/2608

  Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead · CPC title

• A47J36/027 Primary

  Cooking- or baking-vessels specially adapted for use in microwave ovens; Accessories therefor · CPC title

• B29C2045/14327

  anchoring by forcing the material to pass through a hole in the article · CPC title