GB2602124A

GB2602124A - A thermoformed container with paperboard outer

Info

Publication number: GB2602124A
Application number: GB2020156.2A
Authority: GB
Inventors: Reed Harry
Original assignee: Reed Thermoformed Packaging Ltd
Current assignee: Reed Thermoformed Packaging Ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2022-06-22
Anticipated expiration: 2040-12-18
Also published as: GB2602124B; GB202020156D0

Abstract

A thermoformed plastic inner pot (figure 1, 2), shaped to be disposed within and releasably securable to a paperboard outer (figure 1, 3) by at least one mechanical attachment structure, the plastic inner pot having a bottom wall and at least one sidewall extending generally upwardly from the first bottom wall such that the inner surfaces of the bottom wall and at least one sidewall define an open-topped cavity, wherein the thermoformed plastic inner pot is not thermoformed into the paperboard outer. The mechanical attachment structure may be a plurality of integrally formed structures comprising a support flange 8 extending as a protrusion 7 out from an outer surface of the sidewall, on which a paperboard outer can rest, and the container may also comprise at least one nesting flange 11.

Description

A thermoformed container with paperboard outer

Technical Field

The present invention relates to containers, more preferably containers suitable for food packaging which have reduced plastic content, which can easily be recycled, and which can be manufactured cost-effectively.

Background

Thermoformed containers, particularly food containers, are known in the art.

Millions of tonnes of plastic packaging are produced annually, with only a relatively small proportion being recycled (less than 20%). In October 2017, the BBC began broadcasting a TV series, Blue Planet, which raised consumer awareness of the issues surrounding plastic use in packaging. This resulted in an upswing in consumer desire for reduced plastic materials in food packaging. The challenge that is faced by manufacturers is that plastic materials, because of their moisture barrier properties, are particularly well suited to the packaging of foodstuffs, for example chilled ready meals etc. One option for reducing the amount of plastic in packaging such as food packaging is to replace at least some of the plastic material with paperboard material. There are reduced plastic packaging containers which have a thin barrier layer of plastic laminated onto the inner surface of a paperboard container. However, whilst this reduces the amount of plastic in the packaging, the laminated plastic/paperboard then becomes a mixed material that is generally unsuitable for recycling. The same problem is faced when plastic and paperboard are glued together with adhesives.

There are some cups and round-bottomed pots available that do not use laminated plastic on paperboard but have a paperboard outer container which acts as a female mould into which plastic can be directly thermoformed i.e., the plastic pot is directly thermoformed into the outer container as part of the thermo-forming process. This can reduce the amount of plastic used but has the drawback that it requires the plastic to be formed in situ into the correctly shaped paperboard outer and results in a relatively low strength inner plastic structure. As the forming of the plastic cannot occur in the absence of the paperboard outer, the manufacturing costs are relatively high. The machinery and tooling are expensive and typically bespoke, and run speeds tend to be slow (with the process always requiring sequential addition of the outer before the inner can be formed); and it does result in challenges when looking to change the outer, for example to update a design or provide a number of different design outers. This can result in additional production wastage.

It would be understood that it would be desirable to have packaging such as a food container that mitigates or obviates one or more of the problems associated with the prior art.

Throughout the description, the term "thermoforming" refers to a process where a plastic material, typically in a sheet, roll or layer format, is heated and formed into a shape. The term "thermoformed" refers to a product which has been formed by said process. There are various options for forming the material into the required shape. For example, a die, which presses into the plastic sheet, can be used to form the shape (this can be in combination with a shaped mould); a pressurised gas can be applied to the top of the heated plastic material which is then pushed into a shaped mould and/or a vacuum could be applied to draw the heated plastic into a shaped mould. A combination of thermoforming methods could also be used. For example, mechanical pressure can be applied by a die to pre stretch a sheet of heated plastic and then pressure and/or a vacuum is applied to finish the forming operation.

The term "paperboard" refers to any thick paper-based material. Typically, this refers to a paper product which is 200g/m2 or heavier but can encompass paper product which is 160g/m2. Paperboard can be single-ply or multi-ply, most commonly multi-ply. Paperboard is typically made from a wood-based material, but it will be appreciated that other base materials such as hemp, bamboo etc. could be used to form paperboard. Paperboard encompasses cardboard.

References to "plastic" are to any type of suitable plastic that can be thermoformed. Such plastics are well known to a person skilled in the art of thermoforming.

Summary of the Invention

Various further features and aspects of the invention are defined in the claims.

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs.

According to the present invention, there is provided: a thermoformed plastic inner pot, shaped to be disposed within and releasably securable to a paperboard outer by at least one mechanical attachment structure; the plastic inner pot having a bottom wall and at least one sidewall extending generally upwardly from the first bottom wall such that the inner surfaces of the bottom wall and at least one sidewall define an open-topped cavity; wherein the thermoformed plastic inner pot is not thermoformed into the paperboard outer.

Advantageously by combining a plastic inner material with a paperboard outer, less plastic material is required to provide a pot or container which has both appropriate barrier properties and strength. Compared to similar containers there may be 50% less plastic used.

The plastic inner pot acts as a barrier layer ensuring that the container can be used as a food container to contain and or store foodstuff including fresh, chilled and/or frozen foods, whilst the paperboard provides both strength a rigidity to the pot and a surface on which information can easily be printed. As the inner pot is releasably attached to the outer by a mechanical attachment, and particularly as it is thermoformed prior to being releasably secured to the paperboard outer (i.e., it is not thermoformed into the outer) and therefore has sufficient structural strength or rigidity to hold its own shape, it is fully recyclable and very easy to separate the two parts for recycling purposes thus increasing the likelihood that recycling will occur. In particular, the inner pot has sufficient rigidity to be processed in the PET recycling stream, where very low gauge films of less than 100 microns (with less than 200 microns often still being problematic) are too flexible to be granulated and therefore are generally separated out in the recycling stream and go to ERE (energy from waste incineration) or landfill.

Preferably, the mechanical attachment structure extends out from the outer surface of the at least one sidewall and is configured to engage with a corresponding recess in the paperboard outer, the width of the mechanical attachment structure being at least 0.1mm smaller in width or height (preferably width), and preferably at least 0.2mm smaller, than the width or height of the corresponding recess in the paperboard outer.

The width of the mechanical attachment structure being slightly smaller than the aperture into which it will be received assists with locating the outer onto the inner pot, and also assists with the separation of the paperboard outer from the plastic inner. This ease of separation is particularly relevant for increasing the likelihood that either users will separate the component parts (i.e., the paperboard outer from the thermoformed plastic inner) for recycling, or that the separation will occur under the mechanical conditions the packaging will be subjected to during standard household-waste disposal processes. Preferably it is the width of the mechanical attachment structure at its widest point that is at least 0.1mm smaller than the width of the corresponding recess in the paperboard outer.

Preferably, the inner pot is an open topped polyhedron with multiple side walls together surrounding and forming the circumference of the pot around a polygon-shaped (e.g., square, or rectangular) bottom wall.

Alternatively, the inner pot has a rounded, cup-like, shape with a single sidewall forming a circular circumference.

Preferably the top of the at least one sidewall (i.e., the edge of the sidewall furthest away from the bottom wall) comprises a sealing flange which extends outward from the circumference of the inner pot.

The sealing flange provides a flat upper surface to which a sealing film can be heat-sealed. Such heat seal films are well known in the art of food packaging and containers and can act as a gas barrier to improve shelf life when packaging food products.

Typically, the sealing flange is disposed on a substantially horizontal plane in use, which is substantially parallel to the plane formed by the bottom wall of the inner pot.

Preferably the at least one sidewall extends upwards at an obtuse angle from the bottom wall such that the open top of the inner pot has a larger diameter than the diameter of the bottom wall.

Most preferably, the top of the at least one surrounding sidewall is not rolled (i.e., as commonly found at the top rim of a disposable cup, although it may form a 'rollover edge' as is known in the art).

Preferably the mechanical attachment structure is an integrally formed structure.

The mechanical attachment structure is integrally formed with the inner pot (i.e., the wall of the pot and the attachment structure are formed from a single piece of thermoformed plastic).

Preferably there are a plurality of mechanical attachment structures disposed around the outer circumference of the inner pot.

Preferably the mechanical attachment structure is a shaped or formed attachment structure on the inner pot that is configured to engage with a corresponding portion of the paperboard outer.

The mechanical attachment structure is a shaped protrusion. Preferably it is shaped such that it tapers to become narrower as it extends outwards from the at least one sidewall. This can assist with the location of the aperture of the outer onto the shaped protrusion.

Preferably, the mechanical attachment structure comprises a support flange that extends out from the outer surface of the at least one sidewall.

Advantageously, the support or locating flange can act a support on which a paperboard outer can rest or against which a surface of the paperboard outer can abut.

Advantageously, the support flange and the lower surface of the sealing flange on the inner pot together act to mechanically secure the paperboard outer thereto and hold it in position.

As the support flange and the lower surface of the sealing flange are on substantially parallel planes that can retain the walls of a paperboard outer between them. The paperboard outer has some resilience and when the upper and lower edges are located against the support flange and the lower surface of the sealing flange it is held with an interference fit.

Preferably, the support flange extends out from the outer surface of the at least one sidewall on a plane substantially parallel to the plane defined by the bottom wall.

Preferably the support flange is an undercut feature.

Preferably the shaped or formed attachment structure on the inner pot is on the lower half of the at least one surrounding sidewall. More preferably the shaped or formed attachment structure on the inner pot is on the lower third of the at least one surrounding sidewall; yet more preferably the shaped or formed attachment structure on the inner pot is on the lower quarter of the at least one surrounding sidewall; most preferably the shaped or formed attachment structure on the inner pot is substantially at the lower edge of at least one surrounding sidewall adjacent to the bottom wall.

Preferably the inner pot comprises at least one nesting flange.

Preferably, the mechanical attachment structure and the at least one nesting flange are disposed on the at least one side wall, with the nesting flange positioned directly above the mechanical attachment structure such that they together form a de-nesting structure.

Providing a de-nesting structure on the plastic inner pot allows pots to be easily picked by hand or machine so that the container can be easily put together.

Preferably the mechanical attachment structure and the at least one nesting flange are both disposed on the lower portion of the plastic inner pot.

By having both the mechanical attachment structure and nesting flange disposed on the same half, most preferably the lower half, lower third or lower quarter of the plastic inner pot, it ensures that each of these features can be manufactured to have appropriate levels of strength.

Preferably the nesting flange is an integrally formed structure.

The nesting flange is integrally formed with the inner pot (i.e., the wall of the pot and the attachment structure are formed from a single piece of thermoformed plastic).

Preferably there are a plurality of nesting flanges disposed around the inner circumference of the inner pot.

Preferably, the de-nesting structure comprises a nesting flange that extends into the open topped cavity from the inner surface of the at least one sidewall.

Preferably the nesting flange is located directly above the attachment structure.

Advantageously this means that the inner pots can be stacked and the attachment structure from a first pot will rest on the nesting flange of a second pot. This will result in stackable pots which save space for transportation as well as clear separation between the top of the pots and each of the sealing flanges. This ensures the pots can easily be de-nested/de-stacked by either manual handling or by an automated robot.

Preferably the plastic inner pot is food grade material.

It would however be understood that the plastic could be non-food grade depending on the application of the finished container.

Optionally the plastic inner pot is a polyethylene terephthalate (PET) material.

PET is well suited to thermoforming and is relatively readily available as a food grade recycled material.

Preferably the starting plastic sheet material from which the inner pot is made is at least 200 microns Preferably the starting plastic sheet material is a recycled plastic.

Advantageously, if the plastic inner pot is formed from recycled material -when it is attached to a paperboard out the overall package can be at least 50% recycled material.

According to a second aspect of the present invention there is provided a container comprising: a paperboard outer; and the thermoformed inner pot of the first aspect; wherein the thermoformed plastic inner pot is disposed within and releasably secured to the paperboard outer by the least one mechanical attachment structure.

Preferably, the paperboard outer is constructed from a single-sheet foldable blank.

S

Preferably, the paperboard outer comprises at least one paperboard sidewall which is shaped to accurately surround the at least one sidewall of the inner pot.

This provides at least a collar which entirely surrounds the circumference of the inner pot and provides support and rigidity to the wall(s) of the inner pot.

Most preferably, the paperboard outer comprises a paperboard bottom wall and at least one paperboard sidewall extending generally upwardly from the paperboard bottom wall such that the inner surfaces of the paperboard bottom wall and at least one sidewall define an open-topped cavity which is sized to receive the thermoformed inner pot.

It is particularly preferred that the paperboard outer has a base bottom wall and is itself an opened topped container arranged to receive the inner pot within it as this provides additional strength and/or rigidity to both the walls and the base of the pot. The paperboard outer has the same shape as the inner pot and is sized to receive the inner pot therewithin in a close fit, although with an airgap (i.e., not so close as to be difficult to separate as e.g., would occur if the inner pot was thermoformed into the paperboard outer).

Preferably the paperboard outer comprises at least one recess shaped to engage with or receive the attachment structure on the inner pot.

Preferably the at least one recess is an aperture which extends entirely through the paperboard.

Preferably the circumference of the recess is shaped substantially match the circumference of the mechanical attachment structure, with at least 0.1mm, more often at least 0.2mm, clearance on the heigh or width of the recess i.e., the recess is at least 0.1mm, more often at least 0.2mm, wider or higher than the width or height of the mechanical attachment structure, such that the attachment structure can engage with the recess in a close fit.

Preferably, the distance from the upper edge of the paperboard outer to the upper edge of the aperture on the paperboard outer is substantially the same as (or very slightly larger than, e.g., lmm or less,) the distance from the support or locating flange of the inner pot to the underside of the sealing flange at the top of the at least one sidewall of the inner pot.

S

This ensures that the paperboard outer is held by interference fit between the support or locating flange of the inner pot to the underside of the sealing flange at the top of the at least one sidewall of the inner pot Preferably, the upper edge of the paperboard outer comprises a strengthening flange. When the outer is secured to the inner pot, the strengthening flange extends outward from the upper edge of the paperboard outer under the sealing flange of the inner pot.

Advantageously the strengthening flange provides additional strength to the sealing flange which is particularly beneficial when a film is being heat-sealed to said sealing flange.

Typically, the strengthening flange is disposed on a substantially horizontal plane in use, which is substantially parallel to the plane formed by the bottom wall of the inner pot.

According to a third aspect of the present invention there is provided a method of manufacturing the container of the first aspect comprising; obtaining the thermoformed inner pot of the first aspect; obtaining a paperboard outer, shaped such that, when constructed, it will have substantially the same outer profile as the inner pot and be sized so as to receive the inner pot with it in a close fit; mechanically securing the inner pot to the paperboard outer wherein this step is not part of a thermoforming process used to produce the thermoformed inner pot.

Advantageously, as the inner pot is secured to the paperboard outer after it has been thermoformed; it can be more easily separated for recycling purposes and is more economical to manufacture. Further, the process can run on existing standard thermoforming equipment and does not require expensive "in-mould" equipment which has high machinery and tooling costs. The method also provides greater user flexibility as it allows for small batch runs and/or hand assembly at the lower scale end, but the option to run a thermoforming line for inner pots in parallel with an automated assembly line (e.g., an inner pot can be being thermoformed at the same time as an already thermoformed pot is being secured to an outer) at the high volume end.

Preferably the step of obtaining the thermoformed inner pot comprises thermoforming a plastic material on a male mould.

Advantageously, thermoforming on a male mould results in appropriate strength in the mechanical attachment structure and nesting flange.

Preferably the step of thermoforming includes using a moveable tool part to create the undercut profile of the mechanical attachment structure.

Preferably the step of thermoforming includes using a moveable tool part to create the undercut profile of the de-nesting structure.

Optionally the step of receiving the inner pot within the paperboard outer comprises the inner pot being placed into a preformed outer that has been pre-erected into a three-dimensional shape.

Advantageously when the inner pot is placed into the preformed outer, the resilience of the materials is such that the mechanical attachment structure on the inner pot engages with the recess in the paperboard outer. Further the upper edge of the outer locates against the lower surface of the sealing flange of the inner pot and, when present, the strengthening flange sits directly below the sealing flange. The paperboard outer is thus securely attached to the inner.

Alternatively, the step of receiving the inner pot within the paperboard outer comprises the paperboard outer being provided as a flat foldable blank onto which the inner pot is positioned; the edges of the paperboard blank being folded to form a three-dimensional structure which surrounds the inner pot.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, where like parts are provided with corresponding reference numerals and in which:

S

Figure 1 is an image of a tray container according to an embodiment of the present invention; and Figure 2 is an image of an inner pot (inverted) according to an embodiment of the present invention; and Figure 3a is a schematic cross section of a portion of two inner pots in accordance with an embodiment of the present invention that have been stacked together or nested; and Figure 3b is a schematic cross section of a portion of two inner pots in accordance with an embodiment of the present invention that have been stacked together or nested and which include a paperboard outer; and Figure 4 is an image of a cardboard outer blank, which forms the cardboard outer depicted in Figure 1, according to an aspect the present invention; and Figure 5 is an image of an alternative tray container according to an embodiment of the present invention.

Detailed Description

A food tray container 1 in accordance with the present invention is generally depicted in Figure 1. The tray 1 is primarily for the packaging of foodstuff at chilled and ambient temperatures and comprises an open topped thermoformed plastic inner pot 2 with a paperboard outer 3. In use, the inner pot 2 is filled with food and typically a plastic or foil heat seal film (not shown) is heat sealed over the open top. In some cases, a push top lid (not shown) can also be used along with or in place of the heat seal film.

The paperboard outer 3 provides additional rigidity to the inner pot 2 such that a thinner layer of plastic can be used than if the inner port was to be used alone. This ensures that the food tray can give an approximate SO% reduction in volume of plastic used compared to standard plastic trays, and that the recycled content of the food tray can be greater than 30% recycled content and most commonly greater than 50% recycled content.

As can be seen more clearly in the images of the inner pot shown in figures 2 and 3, the inner pot 2 has a bottom wall 4, and four sidewalls 5 which extend upward and outward front the bottom wall 2 to define a cavity 6 and form an open-topped pot. The inner pot has an inverted frusto-pyramidal shape.

It will be appreciated that other shaped pots could be produced, and the number of sidewalls will change accordingly.

The upper edge 12 of the sidewall 5 has a sealing flange 13 which surrounds the entire upper circumference of the inner pot 2. The sealing flange 13 extends outwards from the upper edge 12 to provide a substantially planar surface onto which a film lid (not shown) could be heat sealed. The outside edge of the sealing flange 13 in this embodiment is slanted slightly downwards providing a deflectable downward flange such that the underside of the sealing flange forms an inverted channel 14. It would however be appreciated that the sealing flange 13 could just extend straight out.

The lower part of each sidewall 5 has at least one attachment structure which is in the form of a protrusion 7 from the outer surface of the sidewall 5. In the depicted embodiment of figure land 2, longer walls have two protrusions 7 and the shorter walls one protrusion 7; it would be understood that the number of protrusions 7 could be changed as required but that a larger number would provide additional mechanical securing on larger pots. The protrusion 7 has a substantially flat or planar upper surface in the form of a supporting flange 8 which extends outwards approximately 2-4mm from the sidewall 5 on a plane that is substantially parallel to the plane formed by the bottom wall 4. In this embodiment, the protrusion is at the bottom or lower edge of the sidewall Sand therefore the lower surface 9 of the protrusion 7 is substantially on the same plane as the bottom wall 4. The height (h) (i.e., from the supporting flange 8 to the lower surface 9 of the protrusion 7) of the protrusion is approximately lmm and the depth (d) (i.e., how far it extends out from the sidewall) is approximately 3mm. The width of the protrusion (w) is approximately 8-10mm.

As seen more clearly in the embodiments of figures 1 3a and 3b, the lower part of each sidewall 5 also has at least one nesting flange 11 which extends inwards into the cavity 6 approximately 2-4mm from the sidewall Son a plane that is substantially parallel to the plane formed by the bottom wall 4. The nesting flange 11 extends from the inner surface of the sidewall 5 into the cavity 6. The nesting flange 11, in combination with the lower surface 9 of the protrusion 7 forms a de-nesting structure 10.

The inward extending nesting flange 11 is provided directly above the outwardly extending protrusion 7 in the sidewall 5. In this embodiment the nesting flange 11 is approximately 9mm above the supporting flange 8 of the protrusion 7 and is formed on a substantially parallel plane. This means that a first pot can be stacked inside a second pot and the lower surface 9 of the protrusion 7 will sit on the nesting flange 11 such that they together act as a de-nesting structure. In turn this will mean that the sealing flanges 13 of each of the pots 2 are kept slightly apart even when they are stacked. This ensures the sealing flanges 13 can easily be gripped and the pots 2 de-nested. This is shown most clearly in Figure 3a or 3b which show a portion of two inner pots 2 which have been stacked or nested together.

Notably, as both supporting flange 8 of the protrusion 7 and nesting flange 11 (together being the de-nesting structure 10) are provided at the lower half of the wall, each structure can be thermoformed with an appropriate strength using a male mould.

The paperboard outer 3 is formed from a single piece of paperboard which is shown in a flat unconstructed/unfolded form in figure 4. In this embodiment this is a recycled paperboard material. The paperboard material has some natural resilience in that a wall or base will flex if gentle pressure is applied to its edges and return to its substantially planar configuration when the pressure is released. The single piece of paperboard is in the form of a blank which is shaped and scored such that it can be folded and constructed into an open topped container shape that substantially follows the shape of the inner pot 2 and is sized to receive the inner pot 2 snugly therewithin. The constructed outer 3 has a base wall 15 and four paperboard side walls 16 extending upwardly and outwardly at an obtuse angle therefrom. At the bottom edge of each paperboard side wall 16 there are one or more apertures 17 which are shaped and located to receive the protrusions] of the inner pot 2 when it is placed within the outer 3. The apertures are sized to be 0.1mm wider than the width of the protrusion]. The upper edge of each of the paperboard side walls 16 locates against the underside of the sealing flange 13 within the inverted channel. As the height of the paperboard side wall 16 from the top of the aperture to the upper edge is substantially the same height (or very slightly higher) as the height of the sidewall 5 of the inner pot from the supporting flanges to the upper edge 12 of the sidewall 5, the upper edge 12 of the paperboard side wall 16 will abut the underside of the sealing flange 13. In this manner, each paperboard side wall 16 is mechanically held in place by the protrusion and additional securing is provided as the wall is held between the surfaces of the supporting flange 8 and the underside of the sealing flange 13. The slight resilience of the paperboard is such that it can be push-fit into position. The paper board sidewall is held in a slightly compressed state between the surfaces of the supporting flange 8 and the underside of the sealing flange 13. As the inner pot has been thermoformed prior to attachment and is not thermoformed into the paperboard outer this helps to mechanically attach or secure the paperboard outer to the inner pot.

It will be appreciated that whilst in this embodiment the protrusions] of the inner pot 2 are positioned at the very bottom edge of the inner pot they could in fact be further up the sidewall 5. In this case the apertures 17 would be at a corresponding position on the paperboard side wall 16 of the paperboard outer 3.

In a preferred embodiment, the upper edge of each paperboard side wall 16 is provided with a strengthening flange 18. The strengthening flange 18 extends outwards from the paperboard side wall 16 on a plane substantially parallel to that of the base wall 15 and that of the sealing flange 13 of the inner pot 2. The strengthening flange 18 sits directly below the lower surface of the sealing flange and provides additional strength to the sealing flange when downward pressure is applied thereto e.g., during the heat-sealing process.

As can be seen in Figure 1, in some embodiments the corners of the outer 3 are only held together by the mechanical attachment to the inner pot 2 (without which they will revert to the 2-dimensional formation of a card blank). This embodiment is particularly easy to disassemble for recycling purposes and has the added benefit that, even if the inner pot 2 and paperboard outer 3 are not separated prior to being disposed of, the physical action of the container being sent through the recycling process is likely to result in the mechanical separation of the inner pot 2 from the paperboard outer 3.

However, there are certain other embodiments, such as that depicted in figure 5, where the paperboard outer 3 comprises overlapping sections or tabs arranged such that the corners of the paperboard side walls 16 can overlap and can be joined with adhesive such that the outer can be constructed into a 3 dimensional open-topped structure which is maintained without the presence of the inner pot 2.

Manufacturing options The inner pot is thermoformed before it is mechanically attached or secured to a paperboard outer i.e., there is a two-step process where the inner pot is formed in a first step and the attachment of the inner pot to the outer is a subsequent step. Thermoforming processes known to those skilled in the art are employed.

Typically, the inner pot is manufactured from a 200Rm or higher sheet of PET. In a preferred embodiment, a male mould of the inner pot described above is used and the PET sheet is heated and then thermoformed over the male mould using standard thermoforming technology. As the PET sheet is stretched over a male mould the edges of the sheet that form the open edge of the upper top are thinner than the plastic material closer to the base. The male mould includes shaped portions for the protrusions and the de-nesting structures and the mould is arranged to have movable sections to allow the more complex shapes to be formed. By forming both the protrusions and the de-nesting structures towards the bottom half of the sidewall of the inner pot (i.e., the area closest to the bottom wall, the structures are formed where the plastic material is stronger and as such the structures have appropriate levels of strength and rigidity.

After thermoforming, the inner pot is removed from the mould and is still separate from the outer pot. At this stage, the inner pots can be stacked and sent elsewhere for the outer to be attached, or the outer can be attached straight away. Different outers can be selected as required and it is not necessary to stop or change the inner pot thermoforming process to do so.

If the outer 3 is provided as a flat blank (as shown in figure 4), the inner pot 2 is placed onto the blank such that the bottom wall 4 of the inner pot 2 sits on the base wall 15 of the paperboard outer 3. The paperboard sidewalls 16 are then folded up so that the upper edge of the paperboard outer 3 abuts the lower surface of the sealing flange 13 of the inner pot 2.

The strengthening flange 18 at the top of the paperboard sidewa II 16 then sits in the inverted channel 14 formed under the sealing flange 13. The apertures 17 in the paperboard side walls 16 fit over the protrusions 7, the upper surface of which being the supporting flanges which, together with the abutment of the upper edge of the side wall 16 against the lower surface of the sealing flange 13, mechanically attach the outer 3 to the inner pot 2. As the outer and inner both have some resilient flexibility the outer can effectively be push-fit onto the inner.

Similarly, if the outer 3 is already preformed into a 3-dimensional open topped pot (such as in the alternative embodiment shown in figure 5), the thermoformed inner can be placed into the outer and pushed down until the protrusions 7 engage with the apertures 17. Again, the resilience of one or both other outer 3 and inner pot 2 materials mean that the inner pot 2 can be push fit into the paperboard outer 3, and once the protrusions 7 are aligned with the apertures 17, the protrusion 7 engages with the aperture 17 and the inner is mechanically attached to the outer 3. The paperboard sidewalls 16 of the paperboard outer 3 are then securely held between the lower surface of the sealing flange 13 of the inner pot 2 and the supporting flange 8. This can result in significant productivity gains as it allows the container to be formed in a two-step process and also allows for manual assembly.

In both cases there is an airgap between at least some of the inner wall of the outer and the outer wall of the inner pot.

This differs from processes where an inner plastic material is effectively thermoformed into an outer with the outer acting as a female mould. In these cases, the plastic tends to be thinner and as it is almost laminated onto the inside of the outer (with no space between the inner wall of the paperboard outer and the outer wall of the inner pot) the two materials are difficult to then separate. Any areas where the outer has an aperture results in an extremely close fit which is again very difficult to separate.

In all preferred embodiments no adhesive or permanent fixing is used to bind the inner pot 2 to the paperboard outer 3.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims are generally intended as "open" terms (e.g., the term "including" or "comprising" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations.

However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations).

It will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope being indicated by the following claims.

Claims

CLAIMS1. A thermoformed plastic inner pot, shaped to be disposed within and releasably securable to the paperboard outer by at least one mechanical attachment structure; the plastic inner pot having a bottom wall and at least one sidewall extending generally upwardly from the first bottom wall such that the inner surfaces of the bottom wall and at least one sidewall define an open-topped cavity, wherein the thermoformed plastic inner pot is not thermoformed into the paperboard outer.
2. A thermoformed plastic inner pot as in Claim 1, wherein the mechanical attachment structure extends out from the outer surface of the at least one sidewall and is configured to engage with a corresponding recess in the paperboard outer, the width of the mechanical attachment structure being at least 0.1mm smaller than the width of the corresponding recess in the paperboard outer.
3. A thermoformed plastic inner pot as in any of the previous claims which is an open topped polyhedron with multiple side walls together surrounding and forming the circumference of the pot around a polygon-shaped bottom wall.
4. A thermoformed plastic inner pot as in any of the previous claims wherein the top of the at least one sidewall comprises a sealing flange which extends outward from the circumference of the inner pot to providing a flat upper surface to which a sealing film can be heat-sealed.
5. A thermoformed plastic inner pot as in claim 6, wherein the sealing flange is disposed on a substantially horizontal plane in use, which is substantially parallel to the plane formed by the bottom wall of the inner pot.
6. A thermoformed plastic inner pot as in any of the previous claims wherein the at least one sidewall extends upwards at an obtuse angle from the bottom wall such that the open top of the inner pot has a larger diameter than the diameter of the bottom wall.
7. A thermoformed plastic inner pot as in any of the previous claims wherein the mechanical attachment structure is an integrally formed structure.
8. A thermoformed plastic inner pot as in any of the previous claims wherein there are a plurality of mechanical attachment structures disposed around the outer circumference of the inner pot.
9. A thermoformed plastic inner pot as in any of the previous claims wherein the mechanical attachment structure comprises a support flange, that extends out from the outer surface of the at least one sidewall, on which a paperboard outer can rest.
10. A thermoformed plastic inner pot as in claims 9, wherein the support flange extends out from the outer surface of the at least one sidewall on a plane substantially parallel to the plane defined by the bottom wall.
11. A thermoformed plastic inner pot as in any of claims 9 or 10 wherein the support flange is an undercut feature.
12. A thermoformed plastic inner pot as in any of the previous claims wherein the mechanical attachment structure and an at least one nesting flange are disposed on the at least one side wall with the nesting flange positioned directly above the mechanical attachment structure to provide a de-nesting structure.
13. A thermoformed plastic inner pot as in Claim 12 wherein the mechanical attachment structure and at least one nesting flange are disposed on the lower portion of the plastic inner pot.
14. A thermoformed plastic inner pot as in any of claims 12 or 13 wherein the nesting flange is integrally formed.
15. A thermoformed plastic inner pot as in any of claims 12 to 14 wherein there are a plurality of nesting flanges disposed around the inner circumference of the inner pot.
16. A thermoformed plastic inner pot as in any of claims 12 to 15 wherein the nesting flange extends into the open topped cavity from the inner surface of the at least one sidewall.
17. A container comprising: a paperboard outer; and the thermoformed inner pot of any of claims 1 to 16; wherein the thermoformed plastic inner pot is disposed within and releasably secured to the paperboard outer by the least one mechanical attachment structure, and wherein the inner pot has not been formed by thermoforming it into the paperboard outer.
18. A container as in claim 17 wherein the paperboard outer is constructed from a single-sheet foldable blank.
19. A container as in any of claims 17 or 18 wherein the paperboard outer comprises at least one paperboard sidewall which is shaped to accurately surround the at least one sidewall of the inner pot.
20. A container as in any of claims 17 to 19 wherein the paperboard outer comprises a paperboard bottom wall and at least one paperboard sidewall extending generally upwardly from the paperboard bottom wall such that the inner surfaces of the paperboard bottom wall and at least one sidewall define an open-topped cavity which is sized to receive the thermoformed inner pot.
21. A container as in any of claims 17 to 20 wherein the paperboard outer comprises at least one recess shaped to engage with or receive the mechanical attachment structure on the inner pot.
22. A container as claims 21 wherein the at least one recess is an aperture which extends entirely through the paperboard.
23. A container as in any of claims 17 to 22 wherein the upper edge of the paperboard outer comprises a strengthening flange.
24. A method of manufacturing the container of claims 17 to 23; obtaining the already formed, thermoformed inner pot of claims 1 to 16; obtaining a paperboard outer, shaped such that, when constructed, it will have substantially the same outer profile as the inner pot and be sized so as to receive the inner pot within it; mechanically securing the inner pot to the paperboard outer wherein this step is not part of a thermoforming process used to produce the thermoformed inner pot.
25. A method of manufacturing as in Claim 24 wherein the step of obtaining the thermoformed inner pot comprises thermoforming a plastic material on a male mould.
26. A method of manufacturing as in Claim 24 or 25 wherein the step of thermoforming includes using a moveable tool part to create the undercut profile of either the mechanical attachment structure and/or the de-nesting structure.
27. A method of manufacturing as in any of claims Claim 24 to 26 wherein the step of receiving the inner pot within the paperboard outer comprises the inner pot being placed into a preformed outer that has been pre-erected into a three-dimensional shape.
28. A method of manufacturing as in any of claims Claim 24 to 26 wherein the step of receiving the inner pot within the paperboard outer comprises the paperboard outer being provided as a flat foldable blank onto which the inner pot is positioned; the edges of the paperboard blank being folded to form a three-dimensional structure which surrounds the inner pot.