Patent Description:
In the prior art, <CIT> discloses a container in the form of a disposable cup or rolled edge container, in the form of a container for foodstuffs such as yogurt, or in the form of a paint pot with a lid. The container has a shell and a lining that acts as a barrier layer preventing the contents of the container leaking out of the container. The lining is bonded to the internal surfaces of the shell by an adhesive such that after use, the lining may be peeled away from the shell and disposed of separately from the shell.

Other containers and methods of forming a container are known from the prior art, for example in <CIT>, <CIT>, <CIT> and <CIT>.

The invention is defined by a container for heating a food product according to claim <NUM> and by a method of forming a container according to claim <NUM>.

Those skilled in the art will appreciate the above stated advantages and other advantages and benefits of various additional embodiments reading the following detailed description of the embodiments with reference to the below-listed drawing figures.

The present disclosure relates generally to various aspects of containers, constructs, trays, materials, packages, elements, and articles, and methods of making such containers, constructs, trays, materials, packages, elements, and articles.

<FIG> illustrates a blank <NUM> that is used to form a container <NUM> (<FIG> and <FIG>), not according to the invention, having a base layer <NUM> and a liner <NUM>. In one embodiment, the base layer comprises paperboard (e.g., solid bleached sulphate folding boxboard), or other suitable material that can be recyclable, and the liner <NUM> comprises a plastic layer such as polyethylene, PET material, or any other thermoplastic material, or a bioplastic, such as vegetable oil or starch based plastics. The container <NUM> is suitable for heating a food product (not shown) in an oven such as a convection or conventional heating oven or microwave oven. In the illustrated embodiment, the liner <NUM> is adhered to the base layer <NUM> and is in contact with the food product during heating. After heating the food product, the base layer <NUM> and the liner <NUM> can be separated to allow both the base layer <NUM> and the liner <NUM> to be recycled separately.

The blank <NUM> can be formed from a single ply of material, such as but not limited to paperboard, cardboard, paper, or a polymeric sheet, but alternatively, the blank can be formed from a laminate that includes more than one layer. In one embodiment, the blank <NUM> can include a microwave interactive layer (not shown) such as is common in MicroRite® containers available from Graphic Packaging International of Marietta, GA. The microwave interactive layer can be commonly referred to as, or can have as one of its components, a foil, a microwave shield, or any other term or component that refers to a layer of material suitable for shielding microwave energy and/or causing heating in a microwave oven.

As shown in <FIG>, the blank <NUM> has a longitudinal direction L1 and a lateral direction L2. In the illustrated embodiment, the blank <NUM> has a bottom panel <NUM>, a first end panel <NUM> foldably connected to the bottom panel at a lateral fold line <NUM>, a second end panel <NUM> foldably connected to the bottom panel at a lateral fold line <NUM>, a first side panel <NUM> foldably connected to the bottom panel <NUM> at a longitudinal fold line <NUM>, and a second side panel <NUM> foldably connected to the bottom panel at a longitudinal fold line <NUM>. In the illustrated embodiment, the blank <NUM> includes corner panels <NUM>, <NUM>, <NUM>, <NUM> respective foldably connected to the bottom panel <NUM> at respective oblique fold lines <NUM>, <NUM>, <NUM>, <NUM>. As shown in <FIG>, the corner panels <NUM>, <NUM>, <NUM>, <NUM> are disposed between respective adjacent end panels <NUM>, <NUM> and side panels <NUM><NUM>. In one embodiment, the blank <NUM> includes eight panels (the two end panels <NUM>, <NUM>, the two side panels <NUM>, <NUM>, and the four corner panels <NUM>, <NUM>, <NUM>, <NUM>) extending around a perimeter of the bottom panel <NUM> so that the eight fold lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> form an octagonal perimeter of the bottom panel <NUM>. As shown in <FIG>, each of the fold lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be oblique with respect to its respectively adjacent fold lines and can form an obtuse angle with each of its respectively adjacent fold lines.

In the illustrated embodiment, each of the end panels <NUM>, <NUM>, side panels <NUM>, <NUM>, and corner panels <NUM>, <NUM>, <NUM>, <NUM> include respective flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> at least partially defined by respective fold lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> extending in the respective panels. In one embodiment, adjacent flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are configured to at least partially overlap when the blank <NUM> is formed into the container <NUM>.

As shown in <FIG>, the container <NUM> can be formed from the blank <NUM> by folding the end panels <NUM>, <NUM>, the side panels <NUM>, <NUM>, and the corner panels <NUM>, <NUM>, <NUM>, <NUM> upwardly along the respective fold lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to form an octagonal sidewall <NUM> extending around the octagonal perimeter of the bottom panel <NUM>. In one embodiment, the sidewall <NUM> extends obliquely upwardly and outwardly from the bottom panel <NUM> around the perimeter of the container <NUM>. In the illustrated embodiment, the flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are folded along respective fold lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to extend outwardly from the respective end panels <NUM>, <NUM>, side panels <NUM>, <NUM>, and corner panels <NUM>, <NUM>, <NUM>, <NUM> and are generally parallel to the bottom panel <NUM>. As shown in <FIG> and <FIG>, the flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> form a flange <NUM> that extends outwardly from the sidewall <NUM> around the perimeter of the container <NUM>. In one embodiment, the sidewall <NUM> can extend along substantially the entire perimeter of the bottom panel <NUM>, and the flange <NUM> can extend along substantially the entire perimeter of the sidewall <NUM>. As shown in <FIG>, each of the end panels <NUM>, <NUM>, the side panels <NUM>, <NUM>, the corner panels <NUM>, <NUM>, <NUM>, <NUM>, and the flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of the sidewall <NUM> can be oblique with respect to the respectively adjacent panels and can form an obtuse angle with each of the respectively adjacent panels. Also as shown in <FIG>, the sidewall <NUM> and the bottom panel <NUM> define an interior space <NUM> of the container <NUM> and have an inner surface <NUM> extending along the interior space <NUM>. Also, the container <NUM> can have one or more injection-molded features that can reinforce the flange <NUM> and/or other portions of the container without departing from the disclosure.

In the illustrated embodiment, the container <NUM> is further formed by attaching the liner <NUM> to the inner surface <NUM> of the base layer <NUM> formed from the blank <NUM>. As shown in the perspective cross-sectional view of <FIG>, the liner <NUM> can extend over the bottom panel <NUM>, the sidewall <NUM>, and the flange <NUM>. In the illustrated embodiment, the liner <NUM> can be attached to at least a portion of each of the bottom panel <NUM>, the end panels <NUM>, <NUM>, the side panels <NUM>, <NUM>, the corner panels <NUM>, <NUM>, <NUM>, <NUM>, and the flange portions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In one embodiment, the liner <NUM> can at least partially retain the base layer <NUM> in the shape of the sidewall <NUM> and the container <NUM> in general (e.g., can help prevent the end panels <NUM>, <NUM>, the side panels <NUM>, <NUM>, and the corner panels <NUM>, <NUM>, <NUM>, <NUM> from separating from one another). As shown in <FIG> and <FIG>, the thickness of the liner <NUM> is exaggerated in order to illustrate the configuration of the liner <NUM> in the container <NUM>.

<FIG> shows one embodiment of a system <NUM> and method for forming the container <NUM> that has the base layer <NUM> formed from the blank <NUM> and the inner layer <NUM>. As shown in <FIG>, the system includes a stack <NUM> of blanks <NUM> that are conveyed by a conveyor <NUM> to a container forming mechanism <NUM>. In one embodiment, the container forming mechanism <NUM> can be any suitable mechanism or forming tool that can fold and/or press-form the blank <NUM> into the container <NUM>, which can be similar to and have similar features and/or components as conventional forming tools such as are disclosed in <CIT>. Also, the forming tool can have similar features and components such as the forming tool disclosed in <CIT>, or any other suitable forming tool assembly. The mechanism <NUM> folds the end panels <NUM>, <NUM>, side panels <NUM>, <NUM> and corner panels <NUM>, <NUM>, <NUM>, <NUM> relative to the bottom panel <NUM> to form an unlined initial construct <NUM> that comprises the base layer <NUM> only. The initial construct <NUM> can be fed to a lower die <NUM> by a conveyor <NUM> and a PET plastic film sheet <NUM> can be fed from a supply roller <NUM> above the initial construct <NUM>, the film sheet <NUM> having a thickness between approximately <NUM> and <NUM> microns in one exemplary embodiment. In one exemplary embodiment, the liner material can be a PET film having a thickness of approximately <NUM> microns and having a heat seal coating on the side that is attached to the base <NUM>. Alternatively, the film sheet <NUM> could have any suitable thickness.

In one embodiment, the film sheet <NUM> could have perforations or other features (not shown) to help separate the liner material from the remainder of the sheet <NUM> when forming the container <NUM>. An upper die <NUM> has a heater plate surface <NUM> having a PTFE coating, for example a Teflon® coating. Alternatively, the heater plate surface <NUM> could have a coating of any suitable material or the coating could be omitted. In the illustrated embodiment, the lower die <NUM> is raised in the direction of arrow A toward the upper die <NUM> by means of a pneumatic ram <NUM>, and an initial vacuum is applied to ducts <NUM> to draw the film sheet <NUM> toward the upper die <NUM>. In the illustrated embodiment, the upper die <NUM> is heated to a temperature of approximately <NUM> to <NUM> degrees Celsius or any other suitable temperature. At this temperature the liner material portion of the film sheet <NUM> softens and forms a domed shape (not shown) under the influence of the initial vacuum. In one embodiment, the film can at least partially conform to the concave heater plate surface <NUM> to form the domed shape. Instead of, or in addition to, the initial vacuum, air pressure under the film sheet <NUM> can be employed with similar or equal effect.

In the illustrated embodiment, as the film sheet <NUM> is domed, its temperature increases such that it becomes tacky. Subsequently, film sheet <NUM> can be forced against the inner surface <NUM> of the recess <NUM> of the initial construct <NUM> by means of air pressure either now applied to the ducts <NUM> and/or by means of a further vacuum applied from the bottom side of the film sheet <NUM>. This pressure and/or further vacuum causes the dome shape of the liner material to invert, and the now tacky and stretched liner material of the film sheet <NUM> can adhere smoothly to the inner surface <NUM> of the initial construct <NUM> supported on the lower die <NUM>. In one embodiment, the tackiness of the liner material can cause the liner material to adhere to the base layer <NUM>. The PTFE coated surface <NUM> can aid in the release of the now tacky liner material portion of the film sheet <NUM> should the film sheet <NUM> make contact with the surface <NUM>. The excess or waste portion of the film sheet <NUM> is cut form the edges of the container <NUM>, that now includes the base layer <NUM> formed from the construct <NUM> and the liner <NUM> formed from liner material of the film sheet <NUM>, by known means to leave an unused film portion <NUM> with tray sized apertures. In one embodiment, the unused film portion <NUM> has marginal portions that remain intact around the apertures formed by the removal of the inner layer <NUM> from the film <NUM> so that the unused film portion <NUM> can continue to the take-up reel <NUM>. Alternatively, or in addition, the film sheet <NUM> can have a sacrificial carrier layer (not shown) wherein the liner material separates from the carrier sheet when it is attached to the base layer <NUM>.

In the illustrated embodiment, the lower die <NUM> is lowered by reversing the direction of the ram <NUM>, and a product support plate <NUM> can force the lined container <NUM> from the supporting lower die <NUM> as the ram <NUM> is lowered in order to eject the container <NUM> from the lower die <NUM>. In one embodiment, the product support plate <NUM> can include upward extensions <NUM> that extend through the lower die <NUM> and engage the bottom of the container <NUM> due to the relative motion of the product support plate <NUM> and the lower die <NUM> toward one another. In the illustrated embodiment, the upward extensions <NUM> can position the container <NUM> relative to the lower die <NUM> so that a pusher rod, a puff of air, or other suitable mechanism can urge the container <NUM> onto a downstream conveyor <NUM>. The lined container <NUM> then can be conveyed for packaging and/or further processing by the conveyor <NUM>.

In one embodiment, the above mentioned process can be repeated to allow substantially continuous production of the lined containers <NUM>. Since the above mentioned process can be employed in a variety of products and using different materials, it may be necessary to repeat the steps of heating the film and it may be necessary to then further force the film against the tray with air pressure, a vacuum, and/or another suitable mechanism. In particular, where thicker sheets of lining film are used for the inner layer <NUM> and various thicknesses of paperboard or other materials are used for the base layer <NUM>, one or more repeats of the heating and forcing steps may be required in order for the film <NUM> to adhere to the base layer <NUM> tray effectively.

In one embodiment, the container <NUM>, with the corner panels <NUM>, <NUM>, <NUM>, <NUM> that extend obliquely between adjacent end panels <NUM>, <NUM> and side panels <NUM>, <NUM>, generally includes only obtuse angles between the panels and lacks orthogonal angles. This can help enable the liner material that forms the liner <NUM> to come into contact with more of the surface area of the base layer <NUM> (e.g., relative to a base layer with orthogonal or acute angles, wherein it can be more difficult for the liner material to extend into such corners). Accordingly, the octagonal shape of the sidewall <NUM> can help the liner <NUM> to adhere to the entire surface or to substantially the entire surface of the base layer <NUM> of the container. In one embodiment, the octagonal shape of the sidewall <NUM> can more closely approximate a rounded or circular sidewall than a container with four orthogonal sides.

The manufacturing process described above produces a readily sealable tray which is made mainly from readily recyclable materials (e.g. paperboard or cardboard and thermoplastic materials). If required, the paperboard base layer is readily removable from the thermoplastic film liner (e.g., after use of the container to hold a food product during heating in a microwave oven and/or in a conventional oven) because the degree of adherence between the base layer <NUM> and the liner <NUM> is controllable to give sufficient adherence so that the liner and the base layer remain attached before, during, and/or after heating of an item held in the container while allowing selective separation of the base layer and the liner after use. Using the parameters mentioned above, it has been found that the base layer <NUM> and the liner <NUM> of the container <NUM> are separable following heating of food in the container, such that the two peel apart, leaving no more than <NUM>% of the thickness of the material of the base layer <NUM> stuck to the film of the inner layer <NUM> in one exemplary embodiment. The separated paperboard of the base layer <NUM> and the thermoplastic film of the inner layer <NUM> can be more easily recycled in separate waste streams (e.g., one for paper products and one for polymers) while minimizing the contamination of the liner material with paperboard.

Advantageously, the use of the heater plate <NUM> to heat the film sheet <NUM> prior to its application onto the initial construct <NUM> provides control of the temperature of the film sheet <NUM> and thus the strength of its adherence to the initial construct <NUM>. The use of the heater plate <NUM> also allows differential heating, so, for example, the film sheet <NUM> could be heated to a higher temperature in the flange area <NUM> of the container <NUM>, which in turn causes the liner <NUM> to adhere more strongly to the flange <NUM> than to the remainder of the container <NUM> so that a further tray-sealing film applied to the liner <NUM> in the area of the flange has a more secure anchor to the container <NUM>. In one embodiment, no injection molding features are used for the container <NUM> and a thinner plastic film can be employed, which can reduce the non-recyclable material content of the tray.

A PET plastics film <NUM> has been described above, although it will be understood that other plastics films could be used, for example polyester based polymers could be used. Also a polyethylene could be used and is favored for food packaging that is not heated (e.g., sandwich packs). It can be seen that the disclosure provides in one embodiment food packaging having a composite construction of a plastics inner food-contacting layer <NUM>, bonded to an outer recyclable layer <NUM>, the inner and outer layers being separable after use, such that no more than <NUM>% of the thickness of the outer layer is disposed on the inner layer after separation.

In one embodiment, a lid (not shown) can comprise packaging film that is a thin plastic layer used to preserve and protect a food item contained in the tray and can be removably attached to the flange <NUM> of the container <NUM>. Any plastic film, such as polyethylene, polypropylene, polyethylene terephthalate, polyvinylchloride, polyamide, and ethylene vinyl alcohol, or other suitable material, can be used for forming the lid that is sealed against the sealing surface of the flange <NUM>. Further, adhesives can be used between the lid and the sealing surface of the flange <NUM> without departing from the disclosure.

<FIG> is a plan view of a blank <NUM> for forming a container <NUM> (<FIG>) of a second embodiment of the disclosure which is according to the invention. The second embodiment is generally similar to the first embodiment, except for variations noted and variations that will be apparent to one of ordinary skill in the art. Accordingly, similar or identical features of the embodiments have been given like or similar reference numbers. As shown in <FIG>, the blank <NUM> is similar to the blank <NUM> of the first embodiment except that the end panels <NUM>, <NUM>, the side panels <NUM>, <NUM>, and the flange portions <NUM>, <NUM>, <NUM>, <NUM> are shaped somewhat differently than the respective panels and flange portions of the first embodiment. In addition, the corner panels <NUM>, <NUM>, <NUM>, <NUM> are differently shaped than the corner panels of the first embodiment, particularly at the flange portions <NUM>, <NUM>, <NUM>, <NUM>, which have rounded edges as shown in <FIG> and are larger than the flange portions of the first embodiment. As shown in <FIG>, a lateral fold line <NUM>, <NUM> extends across the respective end panels <NUM>, <NUM>, a longitudinal fold line <NUM>, <NUM> extends across the respective side panels <NUM>, <NUM>, and an oblique fold line <NUM>, <NUM>, <NUM>, <NUM> extends across each of the corner panels <NUM>, <NUM>, <NUM>, <NUM>. The blank <NUM> could be otherwise shaped, arranged, and/or configured without departing from the scope of the invention as defined in the claims.

In the illustrated embodiment, the container <NUM> can be formed from the blank <NUM> and the liner material (e.g., the liner material <NUM>) in a similar or the same manner as described above with respect to the first embodiment. Accordingly, the container <NUM> can include the base layer <NUM> formed from the blank <NUM> (e.g., a solid bleached sulphate folding boxboard) and the liner <NUM> formed from the liner material <NUM> (e.g., a PET film with a thickness of approximately <NUM> microns and with a heat seal coating). As shown in <FIG>, each of the corner flange portions <NUM>, <NUM>, <NUM>, <NUM> can overlap a portion of the respectively adjacent flange portions of the end panels and side panels.

As shown in <FIG>, the lateral fold lines <NUM>, <NUM>, the longitudinal fold lines <NUM>, <NUM>, and the oblique fold lines <NUM>, <NUM>, <NUM>, <NUM> cooperate to form an intermediate fold line <NUM> extending around the sidewall <NUM>. In the illustrated inventive embodiment, the sidewall <NUM> has a lower portion and an upper portion each extending from the intermediate fold line <NUM>, wherein the portions of the sidewall <NUM> are oblique with respect to one another. In one embodiment, the upper and lower portions of the sidewall can cooperate to form an obtuse angle, and the lower portion of the sidewall <NUM> can form a more obtuse angle with the bottom panel <NUM> than the angle between the sidewall <NUM> and the bottom panel <NUM> in the first embodiment. The obtuse angles in the sidewall <NUM> can allow the base layer <NUM> to conform with the liner <NUM> more completely, which can increase the contact between the surfaces of the base layer <NUM> and the liner <NUM> (e.g., at the transitions between the panels of the container <NUM>). The container <NUM> could be otherwise shaped, arranged, and/or configured without departing from the scope of the invention as defined in the claims.

Optionally, one or more portions of the blank or other constructs described herein or contemplated hereby may be coated with varnish, clay, or other materials, either alone or in combination. The coating may then be printed over with product advertising or other information or images. The blanks or other constructs also may be selectively coated and/or printed so that less than the entire surface area of the blank or substantially the entire surface area of the blank may be coated and/or printed.

Any of the blanks, containers, or other constructs of this disclosure may optionally include one or more features that alter the effect of microwave energy during the heating or cooking of a food item that is associated with the tray or other construct. For example, the blank, tray, container, or other construct may be formed at least partially from one or more microwave energy interactive elements (hereinafter sometimes referred to as "microwave interactive elements") that promote heating, browning and/or crisping of a particular area of the food item, shield a particular area of the food item from microwave energy to prevent overcooking thereof, or transmit microwave energy towards or away from a particular area of the food item. Each microwave interactive element comprises one or more microwave energy interactive materials or segments arranged in a particular configuration to absorb microwave energy, transmit microwave energy, reflect microwave energy, or direct microwave energy, as needed or desired for a particular construct and food item.

In the case of a susceptor or shield, the microwave energy interactive material may comprise an electroconductive or semiconductive material, for example, a vacuum deposited metal or metal alloy, or a metallic ink, an organic ink, an inorganic ink, a metallic paste, an organic paste, an inorganic paste, or any combination thereof. Examples of metals and metal alloys that may be suitable include, but are not limited to, aluminum, chromium, copper, inconel alloys (nickel-chromium-molybdenum alloy with niobium), iron, magnesium, nickel, stainless steel, tin, titanium, tungsten, and any combination or alloy thereof.

Alternatively, the microwave energy interactive material may comprise a metal oxide, for example, oxides of aluminum, iron, and tin, optionally used in conjunction with an electrically conductive material. Another metal oxide that may be suitable is indium tin oxide (ITO). ITO has a more uniform crystal structure and, therefore, is clear at most coating thicknesses.

Alternatively still, the microwave energy interactive material may comprise a suitable electroconductive, semiconductive, or non-conductive artificial dielectric or ferroelectric. Artificial dielectrics comprise conductive, subdivided material in a polymeric or other suitable matrix or binder, and may include flakes of an electroconductive metal, for example, aluminum.

In other embodiments, the microwave energy interactive material may be carbon-based, for example, as disclosed in <CIT>, <CIT>, <CIT>, and <CIT>.

In still other embodiments, the microwave energy interactive material may interact with the magnetic portion of the electromagnetic energy in the microwave oven. Correctly chosen materials of this type can self-limit based on the loss of interaction when the Curie temperature of the material is reached. An example of such an interactive coating is described in <CIT>.

The use of other microwave energy interactive elements is also contemplated. In one example, the microwave energy interactive element may comprise a foil or high optical density evaporated material having a thickness sufficient to reflect a substantial portion of impinging microwave energy. Such elements typically are formed from a conductive, reflective metal or metal alloy, for example, aluminum, copper, or stainless steel, in the form of a solid "patch" generally having a thickness of from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches), for example, from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches). Other such elements may have a thickness of from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches), for example, <NUM> (<NUM> inches).

In some cases, microwave energy reflecting (or reflective) elements may be used as shielding elements where the food item is prone to scorching or drying out during heating. In other cases, smaller microwave energy reflecting elements may be used to diffuse or lessen the intensity of microwave energy. One example of a material utilizing such microwave energy reflecting elements is commercially available from Graphic Packaging International, Inc. (Marietta, GA) under the trade name MicroRite® packaging material. In other examples, a plurality of microwave energy reflecting elements may be arranged to form a microwave energy distributing element to direct microwave energy to specific areas of the food item. If desired, the loops may be of a length that causes microwave energy to resonate, thereby enhancing the distribution effect. Microwave energy distributing elements are described in <CIT>, <CIT>, <CIT>, and <CIT>.

If desired, any of the numerous microwave energy interactive elements described herein or contemplated hereby may be substantially continuous, that is, without substantial breaks or interruptions, or may be discontinuous, for example, by including one or more breaks or apertures that transmit microwave energy. The breaks or apertures may extend through the entire structure, or only through one or more layers. The number, shape, size, and positioning of such breaks or apertures may vary for a particular application depending on the type of construct being formed, the food item to be heated therein or thereon, the desired degree of heating, browning, and/or crisping, whether direct exposure to microwave energy is needed or desired to attain uniform heating of the food item, the need for regulating the change in temperature of the food item through direct heating, and whether and to what extent there is a need for venting.

By way of illustration, a microwave energy interactive element may include one or more transparent areas to effect dielectric heating of the food item. However, where the microwave energy interactive element comprises a susceptor, such apertures decrease the total microwave energy interactive area, and therefore, decrease the amount of microwave energy interactive material available for heating, browning, and/or crisping the surface of the food item. Thus, the relative amounts of microwave energy interactive areas and microwave energy transparent areas may be balanced to attain the desired overall heating characteristics for the particular food item.

As another example, one or more portions of a susceptor may be designed to be microwave energy inactive to ensure that the microwave energy is focused efficiently on the areas to be heated, browned, and/or crisped, rather than being lost to portions of the food item not intended to be browned and/or crisped or to the heating environment. Additionally or alternatively, it may be beneficial to create one or more discontinuities or inactive regions to prevent overheating or charring of the food item and/or the construct including the susceptor.

As still another example, a susceptor may incorporate one or more "fuse" elements that limit the propagation of cracks in the susceptor, and thereby control overheating, in areas of the susceptor where heat transfer to the food is low and the susceptor might tend to become too hot. The size and shape of the fuses may be varied as needed. Examples of susceptors including such fuses are provided, for example, in <CIT>, <CIT>, <CIT>, and <CIT>.

All dimensional information presented herein is intended to be illustrative of certain aspects, features, etc., of various embodiments of the disclosure, and is not intended to limit the scope of the disclosure. The dimensions of the blanks, containers, forming tools, features, or any other dimension, can be more or less than what is shown and described in this disclosure without departing from the scope of the invention as defined in the claims and can be within the listed ranges of dimensions for each feature or outside the listed ranges of dimensions for each feature without departing from the scope of the invention as defined in the claims.

The blanks according to the present invention can be, for example, formed from coated paperboard and similar materials. For example, the interior and/or exterior sides of the blanks can be coated with a clay coating. The clay coating may then be printed over with product, advertising, price coding, and other information or images. The blanks may then be coated with a varnish to protect any information printed on the blanks. The blanks may also be coated with, for example, a moisture barrier layer, on either or both sides of the blanks.

In accordance with the exemplary embodiments, the blanks may be constructed of paperboard of a caliper such that it is heavier and more rigid than ordinary paper. The blanks can also be constructed of other materials, such as cardboard, hard paper, or any other material having properties suitable for enabling the carton package to function at least generally as described above.

Claim 1:
A container (<NUM>) for heating a food product, the container (<NUM>) comprising:
a base layer (<NUM>) of material and a liner (<NUM>) releasably attached to an inner surface (<NUM>) of the base layer (<NUM>), wherein the liner (<NUM>) is separable from the base layer (<NUM>) after heating the container (<NUM>);
a bottom panel (<NUM>);
characterised in that
the container (<NUM>) comprises:
an end panel (<NUM>, <NUM>) foldably connected to the bottom panel (<NUM>);
a side panel (<NUM>, <NUM>) foldably connected to the bottom panel (<NUM>);
a corner panel (<NUM>, <NUM>, <NUM>, <NUM>) foldably connected to the bottom panel (<NUM>), the corner panel (<NUM>, <NUM>, <NUM>, <NUM>) extending between the end panel (<NUM>, <NUM>) and the side panel (<NUM>, <NUM>);
a sidewall (<NUM>) extending around the bottom panel (<NUM>), wherein the sidewall (<NUM>) comprises the end panel (<NUM>, <NUM>), the side panel (<NUM>, <NUM>), and the corner panel (<NUM>, <NUM>, <NUM>, <NUM>), and the sidewall (<NUM>) and the bottom panel (<NUM>) at least partially define an interior space (<NUM>) of the container (<NUM>); and
a flange (<NUM>) extending outwardly from the sidewall (<NUM>), the flange (<NUM>) extending along a perimeter of the sidewall (<NUM>);
wherein the sidewall (<NUM>) comprises a lower portion foldably connected to an upper portion along an intermediate fold line (<NUM>) extending in the sidewall (<NUM>), the upper portion being oblique with respect to the lower portion,
wherein a lateral fold line (<NUM>, <NUM>) extends across the end panel (<NUM>, <NUM>), a longitudinal fold line (<NUM>, <NUM> ) extends across the side panel (<NUM>, <NUM>), and an oblique fold line (<NUM>, <NUM>, <NUM>, <NUM>) extends across the corner panel (<NUM>, <NUM>, <NUM>, <NUM>), each of the lateral fold line (<NUM>, <NUM>), the longitudinal fold line (<NUM>, <NUM>), and the oblique fold line (<NUM>, <NUM>, <NUM>, <NUM>) being spaced apart from the bottom panel (<NUM>) and from an upper perimeter of the container (<NUM>);
said lateral, longitudinal and oblique fold lines (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) cooperating to form the intermediate fold line (<NUM>), the intermediate fold line (<NUM>) extending around the interior space (<NUM>); and the intermediate fold line (<NUM>) being spaced apart from the bottom panel (<NUM>) and from the upper perimeter of the container (<NUM>).