Patent ID: 12207378

DETAILED DESCRIPTION

Unless otherwise specified, to the extent used herein, relative positional and orientational terms such as top, bottom, upper, lower, left side, right side, and the like as applied to elements and components of the example embodiments described herein are not intended to be limiting but are used merely for convenience of description and to distinguish among the various elements and components. Persons of ordinary skill in the art will appreciate that the example embodiments described herein and others can be implemented with a variety of different orientations and positions without deviating from the broad concepts embodied therein. Thus, as just one example, those skilled in the art will understand that a reference to a “top” panel of an example embodiment does not necessarily mean that the example embodiment must always be oriented so that the panel is on “top” but is only used to distinguish the panel from other panels, such as another panel referred as a “bottom” panel. Those skilled in the art will understand that in the same example embodiment simply rotated by 180 degrees, the relative positions and orientations of the panels may be reversed but the panels and the described embodiment otherwise remain unchanged.

A. Overview.

FIGS.1A-9illustrate various views of an example biodegradable microwave susceptor10and package or construct50incorporating the susceptor for containing a food item to be heated in a microwave oven.FIGS.12A-21Dillustrate various views of an example biodegradable microwave susceptor10as incorporated in a number of variations of the package or construct50.FIGS.10and11illustrate another example embodiment of a package80incorporating an example biodegradable microwave susceptor10for a food item to rest on at least partially to be heated in a microwave oven.

As shown inFIGS.1A-3and10-11, an example biodegradable microwave susceptor10embodying features of the invention generally comprises a biodegradable substrate15, a susceptor layer20, and an interface layer21. The biodegradable substrate15, susceptor layer20, and interface layer21are arranged in the form of a laminate with the susceptor layer20lying between the biodegradable substrate15and the interface layer21.

The susceptor layer20may have one or more areas of microwave interactive material22and one or more microwave inactive areas24. An area of microwave interactive material22may comprise one or more patterns of microwave interactive material22, e.g., metallized material, corresponding to a pattern or patterns of heat to be applied to a particular food item. A microwave inactive area24is devoid of microwave interactive material, e.g., is demetallized. Other microwave inactive areas26,28,30,32,34,36,38,40,44can be located in areas where it is desired not to apply heat to a food item and in areas where folds or overlaps are to be made to form a construct.

The biodegradable substrate15comprises a biodegradable cellulosic material, preferably a cellophane film. The biodegradable substrate15is arranged on a side of the susceptor layer20that is to be exposed to a food item to apply heat. The biodegradable substrate15may be in contact with the food item in one or more locations where microwave interactive material22and microwave inactive areas24of the susceptor layer20are present in order to distribute the heat to the food item as desired.

The interface layer21is arranged on a side of the susceptor layer20that is opposite to the biodegradable substrate15. To incorporate the susceptor10into a construct, such as example constructs50,80, the interface layer21can be adhered to a flat panel25of paperboard or the like comprising part or all of a blank for forming the construct, thus forming a substantially flat laminate sheet comprising the susceptor10and panel25as best shown inFIGS.1A-3and10-11. Depending on the intended configuration of the construct incorporating the susceptor10, the laminate sheet may be provided with various features such as fold areas48to enable the sheet to be folded or otherwise formed into the desired configuration, as shown and described with respect toFIGS.3-9and12A-21D. Alternatively, if desired based on the nature and shape of a food item to be heated, the laminate sheet may be retained as a substantially flat panel as shown inFIGS.10-11on which a food item can at least partially rest for heating.

B. Biodegradable Substrate.

The biodegradable substrate15of the example biodegradable microwave susceptor10preferably is arranged to cover substantially the entire surface of the susceptor layer20on the side of the susceptor layer20that is exposed to a food item to which heat is to be applied. The biodegradable substrate15preferably comprises a thin film of a biodegradable cellulose-based material or biodegradable polyester, most preferably a cellulose material such as cellophane.

Both metallized and non-metallized cellophane films suitable for use as the biodegradable substrate15are commercially available from various sources. One suitable biodegradable cellophane film is manufactured by Futamura Chemical UK Ltd. in the United Kingdom and is sold under the brand name NATUREFLEX® NVS.

Cellulose-based materials, including cellophane, are manufactured from natural wood fiber and are biodegradable, compostable, and recyclable. This is a major advantage over the thermoplastic polymer materials such as PET and other forms of polyester that have been used previously as substrates for microwave susceptors. Another advantage is that natural cellulose-based materials do not raise the perceived health concerns among consumers that thermoplastic polymer materials do concerning their contact with food items, especially under the extreme temperature conditions of microwave cooking.

As a cellulose product, cellophane has additional properties that are desirable for providing excellent microwave cooking results. In particular, it is capable of generating very high levels of heat as a susceptor substrate without breaking down. This feature can be used to provide improved cooking results essentially limited only by the ability of a food item being cooked to absorb the generated heat. However, while cellophane constitutes a presently preferred material for its desirable properties, it should be understood that other biodegradable high temperature films with similar properties could also be used.

While cellophane's properties make it desirable for use as the biodegradable substrate15for the susceptor layer20, it also has other less favorable attributes that the example embodiments address. For example, unlike PET and other thermoplastic polymer films, cellophane is a non-extensible film. When stressed, it tears like paper rather than stretching. Cellophane also burns like paper under extreme temperature conditions. Thus, a fully metallized cellophane-based susceptor lamination could generate excessive heat and result in scorching or burning of the lamination and construct materials when subjected to microwave heating. In contrast, the thermoplastic polymer films tend to crack or “craze” when subjected to high temperatures. This property acts like a thermostat for a susceptor because as the film surface breaks up, it produces less heat. As a result, the risk of scorching, staining, or charring of the laminate and the construct materials is reduced, as is the risk of ignition.

In addition, cellophane tends to shrink when it is heated. Thus, when areas of microwave interactive material22of the susceptor layer20are present in the fold48and/or overlap areas of a blank from which a construct is formed and the construct is subjected to microwave heating, the heat emitted from the areas of microwave interactive material in those areas can cause the cellophane in those areas to overheat, shrink, and delaminate from the susceptor layer15and the underlying construct panel or blank25. However, it has been discovered that these effects can be prevented by locating microwave inactive areas such as areas26,28,30,34,36,38, and44in the fold48and overlap areas of the laminate comprising the microwave susceptor10and construct panel or blank25. For example, this can be accomplished through the use of selective demetallization of the susceptor layer20in those areas, as described in more detail below, which effectively controls the temperatures generated in those areas. Alternatively, a reduction of the layer of metal or other film used as a microwave interactive material may also prevent excessive heating of the biodegradable substrate15in those areas.

C. Susceptor Layer.

The susceptor layer20of the example biodegradable microwave susceptor10may be comprised of any type of microwave interactive material or materials that absorb electromagnetic energy from microwaves and convert the same to heat for application to a food item. The susceptor layer20is preferably comprised of a suitable metal and more preferably of aluminum. However, various other types of microwave interactive materials may be used including but not limited to ceramics and other materials that have been used previously to construct microwave susceptors.

A metal such as aluminum is particularly preferred for use as a microwave interactive material because of the ease and precision with which it can be manipulated to form defined areas of microwave interactive material22and microwave inactive areas24of the susceptor layer20on the biodegradable substrate15in desired locations and with desired patterns. As described above, metallized cellophane films are commercially available from various sources including Futamura Chemical UK Ltd. in the United Kingdom under the brand name NATUREFLEX® NVS. The metallization layer on these films is suitable for use to construct the susceptor layer20. Alternatively, a conventional thin film vacuum metallization process can be used to initially metallize a surface of the biodegradable substrate15.

Preferably, the susceptor layer20is processed according to the demetallization apparatus and process disclosed in U.S. Pat. No. 6,946,082 to define the areas of microwave interactive material22and microwave inactive areas24of the susceptor layer on the biodegradable substrate15in desired locations and with desired patterns. U.S. Pat. No. 6,946,082 is incorporated herein as if set forth in its entirety. The commercially available films identified above are suitable for use with the apparatus and process of U.S. Pat. No. 6,946,082 to construct the susceptor layer20.

Although other apparatus and methods for processing the susceptor layer20to define and pattern selected areas of microwave interactive material22and microwave inactive areas24devoid of such material will be known to those skilled in the art and could be used if desired, the apparatus and methods described in U.S. Pat. No. 6,946,082 are preferred. Among other things, the process of U.S. Pat. No. 6,946,082 requires a minimal number of steps and provides a simple, rapid, and cost effective means for producing high quality, selectively demetallized microwave susceptor films and microwave susceptor/package laminates.

FIGS.1A,3, and5among others illustrate one embodiment where the susceptor layer20is formed and arranged to have a plurality of different areas where each area has a substantially uniform pattern of microwave interactive material22comprised of a plurality of individual areas of microwave interactive material22isolated from each other by a plurality of microwave inactive areas24. More specifically, in each area the individual areas of microwave interactive material22are substantially uniform square-shaped areas arranged in a substantially symmetrical array and separated by substantially uniform and symmetrical narrow linear microwave inactive areas24. However, those skilled in the art will understand that many pattern variations are possible depending on the configuration of the construct into which the susceptor10is to be integrated, the type and shape of the food item to be heated, the levels and locations of heat to be applied to various portions of the food item, the type of heating to be accomplished, e.g., conduction or infrared, and other considerations.

For example, the individual areas of microwave interactive material22may be shaped as squares, rectangles, circles, triangles, or other regular or irregular geometric shapes. Moreover, the individual areas of microwave interactive material22need not all have the same shape but may include a mix of a plurality of different shapes. Similarly, the individual areas of microwave interactive material22need not all be the same size, and instead the individual areas of microwave interactive material22may have a plurality of different sizes. In the example embodiments illustrated inFIGS.12A-21Dfor instance the individual areas of microwave interactive material22comprise a mix of square and rectangular shapes of different sizes. Similarly, the microwave inactive areas24also may have various uniform or different shapes and sizes and need not be arranged uniformly or symmetrically.

Further, the same pattern of microwave interactive material22and microwave inactive areas24may extend over the entire susceptor layer20or a plurality of different patterns may be present in a plurality of different areas of the susceptor layer20. For example, the surface of one panel of a construct, such as a surface of a top or bottom panel, may correspond to one area of the susceptor layer20and may have one pattern while the surface of another panel, for example a side panel, may comprise another area of the susceptor layer20and may have a different pattern.

Still further, a plurality of different patterns may be present in a plurality of different areas of the susceptor layer20corresponding to different areas or portions of a food item to be heated. For example, one area of susceptor layer20corresponding to one portion of a food item to be heated may have one pattern and a second area of susceptor layer20corresponding to a second portion of the food item may comprise a second pattern. Even further, when the susceptor layer20comprises a plurality of patterns, each pattern may comprise different sized, shaped, and arranged individual areas of microwave interactive material22and microwave inactive areas24.

In this way, a substantial amount of control is gained over the levels, locations, and types of heating to facilitate achieving optimal cooking results. For example, the sizes, shapes, and arrangement of the individual areas of microwave interactive material22making up a first pattern may be selected to direct selected levels of infrared heating to selected surface areas of a food item that are not in contact with the susceptor10but that are exposed to an area of the susceptor10where the first pattern is present. At the same time, different sizes, shapes, and arrangements of the individual areas of microwave interactive material22making up a second pattern may be selected to direct selected level of conduction heating to other selected areas or portions of the food item that are in contact with an area of the susceptor10where the second pattern is present. Alternatively, the sizes, shapes, and arrangements of the individual areas of microwave interactive material22making up a first pattern may be selected to direct a selected level of conduction heating to a selected area or portion of a food item in contact with an area of the susceptor10where the first pattern is present, while the sizes, shapes, and arrangements of the individual areas of microwave interactive material22making up a second pattern are selected to direct another selected level of conduction heating to another selected area or portion of the food item in contact with another area of the susceptor10where the second pattern is present.

Further, referring primarily toFIG.3, the pattern or patterns of microwave interactive material22of susceptor layer20may be interrupted by microwave inactive areas formed in other selected locations of the susceptor layer20. A number of such microwave inactive areas26,28,30,32,34,36,38, and40are illustrated inFIG.3in connection with the laminate comprising the biodegradable microwave susceptor10and a construct panel or blank25.

For example, microwave inactive areas32and40may be selectively formed in the pattern of microwave interactive material22in locations where it desired to form openings in the construct to vent heat or gases as the food item is heated, or in areas where increased microwave passage is desirable to help heat the interior of the food item. Also for example and as described above, microwave inactive areas26,28,30,34,36,38, and44may be selectively formed in locations where the pattern of microwave interactive material22coincide with or correspond to designated fold48or overlap areas of the laminate. These areas are provided to facilitate forming a construct incorporating the susceptor10. However, as described previously, removal of the microwave interactive material22in such areas is effective to prevent potential overheating of the biodegradable substrate15of the susceptor10and possible delamination in those areas. Alternatives to complete removal of the microwave interactive material may include reduction of the layer of metal or other film used as the microwave interactive material in those areas.

D. Interface Layer.

The interface layer21of the example biodegradable microwave susceptor10preferably is arranged to cover substantially the entire surface of the susceptor layer20on the side of the susceptor layer20that is opposite to the biodegradable substrate15. The interface layer21is preferably comprised of a material that is biodegradable and that can be readily adhered to the susceptor layer20on one side and a panel or blank25for a construct on the other side. The interface layer21preferably comprises a biodegradable material, which may be for example a suitable cellulose-based material such as paper or paper-containing material.

The interface layer21can be adhered to the susceptor layer20and to the panel or blank25for a construct using an adhesive that is safe for use around food items and that has suitable adherence and thermal properties when exposed to microwave heating. The biodegradable microwave susceptor10comprising the laminate of biodegradable substrate15, susceptor layer20, and interface layer21is preferably adhered to a panel or blank25for a construct via the interface layer21according to the apparatus and method of U.S. Pat. No. 6,946,082 in order to construct the laminate of the biodegradable microwave susceptor10and construct panel or blank25as shown inFIG.2. The panel or blank25preferably comprises a cellulose-based material such as paper, paperboard, or a similar material suitable for use with the apparatus and method of U.S. Pat. No. 6,946,082 and such material is available from commercial sources.

E. Constructs Incorporating Biodegradable Microwave Susceptor.

Turning now to a description of constructs incorporating the biodegradable microwave susceptor10,FIGS.4-9illustrate an example embodiment of a construct50. Construct50is formed from a substantially flat laminate of the biodegradable microwave susceptor10and the blank25shown inFIG.3. The laminate is shaped and sized to form the construct50with an intended size and configuration. The laminate may be provided with selected fold48and overlap areas to facilitate formation of the construct in the desired configuration. As described above, microwave interactive material may be removed from the fold48and overlap areas so that they comprise microwave inactive areas26,28,30,34,36,38,44. To facilitate partial or complete folding of the laminate in the identified areas, one or more perforations, creases, or the like may be provided in the fold areas48.

In one approach, the example construct50may be formed from the flat laminate shown inFIG.3by folding the laminate in fold areas30,34toward each other by approximately 90 degrees so that the patterns of areas of microwave interactive material22on the surfaces of the folded sections face toward each other. Next, the laminate is folded in fold areas26and38by approximately 90 degrees so that the patterns of areas of microwave interactive material22on the surfaces of the folded sections face downwardly and inwardly and the overlap area of one folded section overlaps and overlies a corresponding portion of the surface of the other folded section that faces outwardly. The overlap area can be permanently attached to the outwardly facing surface of the other folded section using a suitable adhesive. Finally, the laminate may be slightly or partially folded in fold areas28and36to create a slight indent or crease as illustrated inFIGS.4-6.

As formed, construct50is generally comprised of a first panel52, a second panel62, a third panel54, and a fourth panel56. The panels50,52,54, and56are arranged and interconnected to define a space68for a food item. Each of the panels50,52,54, and56has a surface exposed to the space68. The biodegradable microwave susceptor10is preferably present on at least one of the surfaces of the panels50,52,54, and56exposed to the space68and preferably all of them. Accordingly, one or more areas or portions of a food item in the space68may be exposed to and may be in contact with one or more areas of the biodegradable microwave susceptor10. More specifically, one or more areas or portions of the food item may be exposed to and may be in contact with the biodegradable substrate15of the susceptor10in one or more locations where one or more areas of microwave interactive material22and one or more microwave inactive areas24of the susceptor layer20are present.

More specifically, the example construct50has the form of an elongated open-ended sleeve as shown inFIGS.4-6and others. Alternatively, the laminate from which the construct50is formed, may include additional panels and fold areas so that one or both ends of the construct50may be selectively opened and closed, for example by a foldable end flap or end panel.

The sleeve of construct50is comprised of a substantially flat elongated top panel52having an inner surface and an outer surface with substantially parallel longitudinal edges58and60, an opposing substantially flat elongated bottom panel62having inner and outer surfaces with substantially parallel longitudinal edges64and66, and opposing side panels54and56each having inner and outer surfaces. Side panel54connects the longitudinal edges58and64of the top and bottom panels respectively, and side panel56connects the longitudinal edges60and66of the top and bottom panels respectively, thereby forming an elongated open-ended sleeve with an interior space68, which is configured to contain a food item to be heated in a microwave oven.

The biodegradable microwave susceptor10is present on one or more and preferably all of the inner surfaces of each of the top, bottom, and side panels52,54,56,62, with patterns of microwave interactive material22being present on the inner surfaces except where the patterns are interrupted by microwave inactive areas. For example, as previously described and as shown inFIGS.3,5, and others microwave inactive areas26,30,34and38can be seen on the inner surfaces of the side panels54and56in the fold areas48where the side panels54,56connect to the respective longitudinal edges58,60,64, and66of the top and bottom panels52,62. Microwave inactive areas32and40also can be seen on the inner surfaces of the side panels54and56overlapping microwave inactive areas28and36respectively where an inward indent or crease in the side panels54and56may bring the biodegradable microwave susceptor10into contact with a food item in the interior space68of the construct50

It will be appreciated that numerous other construct configurations, including those shown and described in U.S. Pat. Nos. 8,492,690; 8,314,373; 7,807,950; and 7,525,075 by the inventor of the present invention are possible, are suitable for use with the biodegradable microwave susceptor10, and are incorporated herein to that extent. Still other possible construct configurations in which the biodegradable microwave susceptor10is suitable for use are shown and described in Japanese Pub. No. JP2002-347756 to Kato, Japanese Pub. No. JP2003-63565 to Kato, U.S. Pub. No. 2004/0023000 to Young, U.S. Pub. No. 2003/0206997 to Winkelman, U.S. Pub. No. 2004/0101605 to Sigel, U.S. Pat. No. 4,948,932 to Clough and UK Patent Pub. GB2365000 to Somers, which also are incorporated herein to that extent.

FIGS.10-11illustrate another example construct80incorporating biodegradable microwave susceptor10. No folds or overlaps are required to form construct80. Rather the completed construct retains the substantially flat form of the laminate of the biodegradable microwave susceptor10and panel25shown in exploded form inFIG.10and laminated inFIG.11. Construct80provides a substantially flat surface that incorporates the biodegradable microwave susceptor10and that a food item can be placed on and can rest on at least partially as heat is applied to the food item in a microwave. The food item to be heated is preferably placed directly on the surface incorporating the susceptor10but may also be supported by a platform or the like in close proximity to the surface. Construct80is thus well-suited for heating relatively thin and flat food items, such as pizzas. Construct80may have its periphery formed approximately in the shape of the food item to be heated if desired. Although illustrated as a substantially circular shape, it will be readily appreciated that any other shape could also be used.

It will also be appreciated that the pattern or patterns of microwave interactive material areas22and microwave inactive areas24of the susceptor layer20shown inFIGS.10-11may be varied as desired or necessary in the same way as described previously. Similarly, the shapes, spacing, and arrangement of the microwave interactive material areas22and microwave inactive areas24may be varied as desired or necessary in the same manner as described previously. It further will be appreciated that, while not shown inFIGS.10-11, other microwave inactive areas could be formed in selected locations of the susceptor layer20as needed or desired also as previously described.

F. Additional Alternative Embodiments.

FIGS.12A through21Dillustrate various alternative embodiments of a variation of the construct50that does not have a top panel52and instead is open at the top in a tray type of structure having a U-shaped cross sectional shape defining an interior space for receiving the food item to be heated in a microwave. One or both of the ends of the construct50shown inFIGS.12A through21Dmay also be open or closed similar to the prior discussed embodiments. It is preferable that the side panels54,56of the embodiments of the package50shown inFIGS.12A through21Ddo not include any microwave interactive material because the side panels54,56are typically not in contact with the food during heating in a microwave and the side panels54,56will not get hot so a consumer can grasp the side panels54,56easily and comfortably.

FIGS.12A through21Dillustrate various embodiments having a pair of side panels54,56extending longitudinally along and upwardly from the sides of the bottom panel62. The embodiment shown inFIG.21Aillustrates the side panels54,56each having an upper straight edge with two opposing slanted ends. The embodiments shown inFIGS.13A and18Aillustrate the side panels54,56each having upper straight edges extending horizontally and straight vertical opposing ends. The embodiments shown inFIGS.12A,14A,15A,16A,17A,19A and20Aall show various side panels54,56having rounded opposing ends and rounded upper edges. The side panels54,56may have various other shapes and sizes depending on the application and the food item to be heated in the package50.

As shown inFIGS.12B,13B,14B,15B,16B,17B,18B,19B,20B and21Bof the drawings, the bottom panel62has an elongated rectangular shape.FIGS.12B,13B,14B and15Billustrate one version of the bottom panel62having two opposing rounded ends that extend outwardly from the side panels54,56. The bottom panel62may have various other shapes and sizes depending on the application and the food item to be heated in the package50.

As further shown inFIGS.12B,13B,14B,15B,16B,17B,18B,19B,20B and21Bof the drawings, a plurality of areas of microwave interactive material22are formed with microwave inactive areas24between them. As shown inFIG.12B, the areas of microwave interactive material22and the microwave inactive areas24may be arranged to form a grid-like pattern. As further shown inFIG.12B, some or all of the areas of microwave interactive material22extending around the perimeter of the bottom panel62may have a smaller square shape than interior areas of microwave interactive material22. As further shown inFIG.12Bof the drawings, a plurality of middle areas of microwave interactive material22may extend longitudinally in two opposing rows along the side portions with each having an elongated rectangular shape extending longitudinally with the construct50. As further shown inFIG.12B, some or all of the interior areas of microwave interactive material22may have a larger square shape with the plurality of interior areas of microwave interactive material22extending longitudinally in a row within the construct50. The areas of microwave interactive material22may have various other shapes, patterns and sizes depending on the application and the food item to be heated in the construct50.

G. Operation of Embodiments.

In use, a food item to be heated may be placed in the space68of the example sleeve of construct50ofFIGS.3-9or the open tray of the variation of construct50ofFIGS.12A-21D, or placed on or in proximity to the flat surface of the construct80ofFIGS.10-11. The construct with the food item to be heated may be placed in a suitable microwave oven and the microwave oven activated for a period of time suitable to heat the food item as desired or necessary. While the microwave oven is activated, the electromagnetic energy of the microwaves is absorbed by the biodegradable microwave susceptor10incorporated in the construct and converted to heat. Depending on whether the food item being heated is in contact with the surface of the susceptor10or there is an air gap between the surface of the susceptor10and the surface of the food item, the susceptor10will heat the food item by conduction, infrared radiation or a combination of both. Upon completion of the heating process, the food item may be removed from the construct, and the construct may be properly disposed of.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the biodegradable susceptor, suitable methods and materials are described above. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety to the extent allowed by applicable law and regulations. The biodegradable microwave susceptor may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive. Any headings utilized within the description are for convenience only and have no legal or limiting effect.