Susceptors capable of balancing stress and effectiveness
View Patent ↗An outer portion of one or more layers of microwave interactive material, which is for becoming hot when exposed to microwave energy, is arranged in a manner that seeks to advantageously control heating, so that the outer portion of the microwave interactive material can safely be adjacent the periphery of a turntable tray. The turntable tray can be heated by the microwave interactive material so that a peak thermally induced stress occurs in the turntable tray at a position proximate the periphery of the tray. The layer(s) of microwave interactive material are configured in a manner so that the peak thermally induced stress is less than a predetermined amount.
1. A method of heating food in a microwave oven having a disk-shaped turntable tray, the method comprising:
placing the food and a construct on the tray in the microwave oven, so that the tray is supporting the construct, and the construct is supporting the food, wherein
the construct comprises a susceptor that is supporting the food,
the susceptor comprises a layer of microwave interactive material mounted to a support layer,
the layer of microwave interactive material is operative for becoming hot when exposed to microwave energy,
the support layer is substantially polygonal-shaped, so that the support layer comprises a plurality of edges and a plurality of corners,
the food extends substantially to the edges of the support layer,
the layer of microwave interactive material comprises a plurality of edges and a plurality of beveled corners that are configured such that the layer of microwave interactive material is generally polygonal-shaped,
the layer of microwave interactive material extends substantially to the edges of the support layer, so that the edges of the layer of microwave interactive material are respectively substantially collinear with the edges of the support layer, comprising
the edges of the layer of microwave interactive material respectively being proximate the edges of the support layer, and
the edges of the layer of microwave interactive material respectively extending along the edges of the support layer,
the beveled corners of the layer of microwave interactive material are respectively adjacent the corners of the support layer,
each beveled corner is inwardly recessed from the respective adjacent corner of the support layer, so that a substantial portion of each of the corners of the support layer is not covered by the layer of microwave interactive material, and
the placing step comprises arranging the construct in a predetermined position on the tray so that each beveled corner is both proximate and inwardly recessed from an outer periphery of the tray; and
operating the microwave oven while the construct is in the predetermined position on the tray, so that
the layer of microwave interactive material is exposed to microwave energy and becomes hot,
the food is heated substantially to the edges of the support layer by the hot layer of microwave interactive material,
the tray is heated by the hot layer of microwave interactive material so that peak thermally induced stresses occur in the tray at locations proximate each beveled corner, and
each of the peak thermally induced stresses is less than a predetermined amount in response to each of the corners of the layer of microwave interactive material being beveled so that each of the corners of the layer of microwave interactive material is inwardly recessed from the outer periphery of the tray.
2. The method according to claim 1 , further comprising providing the construct, wherein the providing step comprises:
optimizing effectiveness of the susceptor, comprising extending the layer of microwave interactive material substantially to the edges of the support layer, so that the edges of the layer of microwave interactive material are respectively substantially collinear with the edges of the support layer, comprising
the edges of the layer of microwave interactive material respectively being proximate the edges of the support layer, and
the edges of the layer of microwave interactive material respectively extending along the edges of the support layer; and
controlling stress in the tray, comprising omitting the layer of microwave interactive material from the substantial portion of each of the corners of the support layer, so that each beveled corner is inwardly recessed from the respective adjacent corner of the support layer.
3. The method according to claim 1 , wherein the tray has a tensile strength, and the predetermined amount is the tensile strength, so that each of the peak thermally induced stresses is less than the tensile strength of the tray.
4. The method according to claim 1 , wherein the arranging step comprises arranging the construct in the predetermined position on the tray so that each corner of the support layer is inwardly recessed from the outer periphery of the tray.
5. The method according to claim 1 , wherein:
the construct is a carton;
the support layer is a polygonal bottom panel of the carton; and
the carton comprises side panels respectively extending upwardly from the edges of the bottom panel.
6. The method according to claim 1 , wherein the layer of microwave interactive material has an optical density of less than about 0.5.
7. The method according to claim 1 , wherein the layer of microwave interactive material has a thickness of less than about 200 angstroms.
8. The method according to claim 1 , wherein inwardly of the outer periphery of the layer of microwave interactive material, the layer of microwave interactive material is substantially continuous throughout all of the area bounded by the outer periphery of the layer of microwave interactive material.
9. The method according to claim 3 , wherein the layer of microwave interactive material comprises interspersed areas that are substantially transparent to microwave energy.
10. The method according to claim 1 , wherein the layer of microwave interactive material extends to within about 0.1 inches of at least one of the edges of the support layer.
11. The method according to claim 1 , wherein for each edge of the plurality of edges of the support layer, the layer of microwave interactive material extends to within about 0.1 inches of the edge.
12. The method according to claim 1 , wherein each beveled corner is curved.
13. The method according to claim 1 , wherein:
the layer of microwave interactive material is a first layer of microwave interactive material;
the susceptor further comprises a patterned layer of microwave interactive material that is operative for becoming hot when exposed to microwave energy; and
the patterned layer of microwave interactive material covers the corners of the support layer.
14. The method according to claim 13 , wherein per unit area, the first layer of microwave interactive material is more absorbent of microwave energy than the patterned layer of microwave interactive material.