WO2008028222A1

WO2008028222A1 - Improvements in containment of food

Info

Publication number: WO2008028222A1
Application number: PCT/AU2007/001290
Authority: WO
Inventors: Guido Calkoen
Original assignee: Thermapak Pty. Ltd.
Priority date: 2006-09-05
Filing date: 2007-09-05
Publication date: 2008-03-13

Abstract

The invention provides laminated materials (5, 75, 105, 145), for use in making thermally insulating containers for items of food and containers (10, 40, 50, 100), formed using the laminated materials. The laminated materials comprise in order: a first lamination layer 1, (or 71, 101, 146) comprising a layer of a material adapted to absorb and retain moisture; a second lamination layer 2, (or 72, 102 147) impervious to movement of fluids therethrough and comprising a layer of metallic foil; and a third lamination layer 3 (or 73 or 103 or 148) comprising a layer of thermally insulating material, with the first and second layers being secured to each other over at least a portion of their adjoining surfaces and the second and third layers being secured to each other over at least a portion of their adjoining surfaces. The laminated materials when used in food containers are effective in limiting the rate of cooling of the contained food and avoiding sogginess.

Description

IMPROVEMENTS IN CONTAINMENT OF FOOD

FIELD OF THE INVENTION

The invention described here relates to a laminated material suitable for food containers and to containers made from the laminated material. The invention is applicable to containers for food that is hot.

BACKGROUND ART

It is now common for foods to be bought cooked and still hot and ready for consumption. Such food is often termed "take-away" or "take-out" food. Examples of such foods, which are sold in vast quantities, include fish and chips, pizza, roast chicken, hamburgers and the like.

In the marketing of take-away food, the food is normally provided to the customer in packaging that is adapted to keep the food hot for a reasonable time, rather than allowing the food to cool too quickly so that it has to be reheated or, If reheating is not possible, so that it becomes unappetizing due to its low temperature. Thus thermal insulating qualities are important. It is also desirable that the food in its packaging not become excessively soggy or greasy, and that the packaging itself not deteriorate excessively while the food is in it, as the food may be harmed or oily or greasy exudates may damage surfaces on which the packaging is placed. Finally, reasonably low packaging cost is always desirable.

A particular problem with some foods (fish and chips and, particularly, pizza) is that moisture is released as vapour from the food during and after cooking. This can condense within the packaging and fall onto the food making it soggy and unappetizing. The nature of pizza, which is provided in flat packages, makes its packaging especially prone to this problem. Venting the vapour can cause excessively rapid cooling. Where packaging is of paper, papier mache or cardboard, moisture can also weaken the packaging. Much effort has been devoted to the packaging of pizza containers in particular, but no entirely satisfactory container is known.

The present invention provides an improved packaging material and containers made therefrom, which addresses these problems and is believed to represent a useful alternative in the market. SUMMARY OF THE INVENTION

Throughout this specification, including the appended claims, the word "comprise" and words derived therefrom such as "comprising" and "comprised", when used in relation to a set of integers elements or steps are to be taken as indicating that the elements integers or steps are present but are not to be taken as precluding the possible presence of other elements integers or steps.

According to a first aspect of the invention, there is provided a laminated material for use in making thermally insulating containers for items of food comprising, in order:

(a) a first lamination layer, comprising a layer of a material adapted to absorb and retain moisture;

(b) a second lamination layer, impervious to movement of fluids therethrough and comprising a layer of metallic foil; and

(c) a third lamination layer, comprising a layer of thermally insulating material, the first and second layers being secured to each other over at least a portion of their adjoining surfaces and the second and third layers being secured to each other over at least a portion of their adjoining surfaces.

It has been found surprisingly convenient that the second lamination layer prevents moisture and food exudates from migrating outwardly to the third layer but also enhances the thermal performance of containers incorporating the laminated material, i.e. in limiting the cooling rate of contained food.

The term "lamination layer" as mentioned above may itself consist of one layer of material or of several layers.

The first lamination layer may comprise a layer of unsized paper. The first lamination layer is preferably adapted to absorb and retain in addition to water at least a proportion of greasy or oily foodstuff exudates.

The first lamination layer may comprise a layer of absorbent paper.

The absorbent paper may comprise blotting paper formed using cotton fibres.

The absorbent paper may have a basis weight of about 250 gm/sq. m.

The absorbent paper is preferably capable of absorbing water to a level of approximately 120 ml/sq. m.

The second lamination layer may comprise a layer of aluminium or of an alloy including aluminium.

The metallic foil may have a thickness of about 0.5mm (0.020 inch).

The third lamination layer may comprise a paperboard layer.

The third lamination layer may comprise at least one paperboard layer and at least one layer of, or at least partially comprising, a polymer plastics material. One example only of such a material is described in US Patent 6307192, of which the "B1" publication dated 23 October 2001 is hereby incorporated in its entirety by reference.

The or a said polymer plastics material layer may lie adjacent to the second lamination layer with bonding of the second and third lamination layers being by that polymer plastics material.

In one embodiment the third layer is itself layered and comprises a paper layer and secured thereto a layer of corrugated paper, and wherein the. layer of corrugated paper is adhesively secured to the second lamination layer. In another embodiment the third layer is itself layered and comprises two paper layers and adhesively secured between said two paper layers a third layer comprising corrugated paper, and wherein one of said two paper layers is secured adhesively to the second lamination layer.

The third lamination layer may comprise a papier mache or paperboard layer.

The third lamination layer may comprise an extruded plastics layer having elongate air cells each of which cells is between opposing face sheets and between walls extending between said face sheets. The third lamination layer may comprise a layer of corn starch plastic in sheet form.

In another possible embodiment, the third lamination layer is a lamination layer of flexible sheet material. The following paragraphs (g) to (j) apply to this embodiment.

(g) The flexible sheet material may comprise a non-woven web containing high density polyethylene (HDPE) fibres.

(h) The flexible sheet material may comprise a layer of DuPont "Tyvek" material. (i) The third lamination further may comprise a layer of "bubble pack" material as herein described.

(j) The third lamination layer further may comprise a layer of non-woven fibrous vegetable material, for example derived from coconut fibre or rice husks. In a further aspect the invention provides a food container having a food-holding part with a floor and walls extending peripherally around and upwardly from the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein the food container is formed from a laminated material as disclosed above and the first lamination layer of said laminated material faces inwardly of the said internal space.

The food-holding part and the lid portion may be formed integrally with each other, and hingedly connected to each other, or may be separate.

The food container may be formed from a flat blank of the laminated material.

The invention further provides a food container having a food-holding part with a floor and walls extending peripherally around and upwardly from the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein a first portion only of said food container comprises a laminated material as disclosed herein and wherein a further portion comprises an integral extension of the third lamination layer of said first portion.

The invention still further provides a food container having a food- holding part with a floor and walls extending peripherally around and upwardly frorn the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein a first portion only of said food container comprises a laminated material as disclosed herein and wherein a further portion comprises integral extensions of the second and third lamination layers of said first portion said integral extensions being themselves secured adhesively to each other.

In a further aspect, the invention provides a method for forming a food container including the step of pressing and forming a piece of a laminated material as disclosed herein between opposing shaped platens, preferably with additional application of heat through the platens.

The invention further provides a method for forming a food container including the steps of preparing a flat blank of laminated material as disclosed herein, and forming the food container from the blank by manipulation that includes folding of the blank. The invention still further provides a method for forming a laminated material according to any one of claims 1 to 14 including the steps of firstly placing between each adjacent pair of said lamination layers a quantity of material that on application of heat adheres to both of the lamination layers of each pair and of secondly applying heat to said pairs whereby to bind said pairs of lamination layers together.

In order that the invention may be better understood there will now be described, non-limitingly, preferred embodiments of the invention as shown in the attached Figures, of which:

Figure 1 is a cross-sectional view of a portion of a laminated material according to the invention;

Figure 2 is a perspective view of a first food container according to the invention, in an open condition;

Figure 3 is a sectional view of the container shown in Figure 2, the section being taken at Station 2 - 2; Figure 4 is a perspective view of a second food container according to the invention, in an open condition;

Figure 5 is a perspective view of a third container according to the invention, shown in a part-manufactured condition; Figure 6 is a cross-sectional view of a portion of a further laminated material according to the invention;

Figure 7 is a perspective view of a fourth container according to the invention; Figure 8 is a cross-section through the container shown in Figure 7, nthe section being taken at station 8-8;

Figure 9 is a cross-sectional view of a portion of a still further laminated material according to the invention;

Figure 10 is a view on a face of a flat blank from which the container of Figure 7 may be formed;

Figure 11 is a cross-sectional view of a portion of a yet further laminated material according to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows in section a portion 5 of a laminated material according to the invention that is useful for thermally insulating food containers. Material 5 has three layers.

A first lamination layer 1 is the innermost one in containers formed from material 5, and is a moisture absorbing and retaining layer. As discussed further below, in use of material 5 in food containers, lamination layer 1 acts to absorb and retain moisture that is released as steam and water vapour from food in the container, thereby limiting any tendency for that moisture to re- enter the food making it soggy and unappetizing. In addition, with some combinations of food and layer 1 material, lamination layer 1, where it is below the food, may also tend to absorb and retain at least a proportion of grease or oily liquids that may be exuded from the contained food. One possible material for lamination layer 1 is blotting paper, e.g. cotton-fϊbre- based blotting paper. This is obtainable, for example only, with a basis weight of about 250 g/square metre and the ability to absorb water to a level of about 120 ml/square metre. Second lamination layer 2 of material 5, when material 5 is used in a container, lies outside layer 1 and comprises a layer of metallic foil or a layer of a plastics material such as Mylar, with metailic foil embedded therein. Lamination layer 2 acts as a physical barrier to moisture movement from innermost lamination layer 1 outwardly through material 5. Such movement cah lead to weakening, discolouring and wetting of the outer layers. In addition, it is found that the ability of material 5 to limit cooling of food in containers is enhanced by inclusion of the fpoil layer. A metallic, and in particular aluminium, foil thickness of about 0.020 inches (0.5mm) has been found to be a satisfactory choice in developmental work. However, this statement is not intended to limit the scope of the invention to this thickness or to aluminium foil.

Third lamination layer 3 of material 5 comprises a layer that provides thermal insulation. In some embodiments, as disclosed below, lamination layer 3 also provides enough rigidity to maintain the form of the container. Lamination layer 3 may itself be a laminated material having several layers. Although other possible materials usable for layer 3 will be discussed below, one possible choice for layer 3 is a paperboard-type material of the type having on at least one side a coating or layer of a polymeric material. Such materials are known in the food packaging art, having been developed as formable and ovenable paperboard materials, i.e. materials which can be formed into dished food containers which retain their shape and which can be placed directly into an oven to cook food contained therein. The polymeric layer in such materials is chosen to withstand the temperatures of cooking and to provide a barrier against moisture and grease. Also as disclosed below, a so-called corrugated cardboard layer may be used for the third, outermost layer.

Lamination layers 1 , 2 and 3 are bonded together by means appropriate to the particular materials used for those layers. Where appropriate, a suitable adhesive can be used between any two adjacent layers. A suitable adhesive may be a rubber-based adhesive able to accommodate deflection associated with forming of the material 5. Where the materials of a given pair of lamination layers are such as to allow it, bonding of that pair of lamination layers may occur without the need for a separate adhesive. For example, where lamination layer 3 comprises a paperboard with a polymeric surface layer as mentioned above, it is possible for that polymeric layer to be positioned against layer 2 and to act as an adhesive when heat is applied during lamination of layers 1 to 3/ Bonding of pairs of lamination layers may be made either continuously over the whole area of the pair of layers or in defined areas only of their interface area. Thus, where an adhesive is provided between a pair of lamination layers, it may be applied in a pattern of dot-like areas on one or both of the lamination layers to bond to the adjacent lamination layer.

Figures 2 and 3 show a pizza container 10 made from the material 5. Container 10 comprises a single piece of the laminated material 5, moulded to shape, to form a lower section 11 and an upper section 12 joined by a hinge section 213. Lower section 11 comprises: (a) a bottom wall 9 having an upper surface 13 on which a pizza

(not shown) can be placed;

(b) a wall 14 extending generally upwardly and outwardly from the periphery 15 of bottom surface 13; and

(c) extending outwardly from a top edge 16 of wall 14, a planar flange 17 having an upper surface 18.

Upper section 12 acts in use as a lid, and comprises:

(d) a wall 8 having a surface 19, shown in Figure 2 as facing upward, but that in use faces inwardly and downwardly towards a pizza placed on bottom surface 13; (e) a generally frusto-conical wall 20 extending generally outwardly

(and upwardly as seen in Figure 2) from periphery 23 of surface 19; and (f) extending outward from wall 20 a planar flange 24 of upper section 12.

Manufacture of container 10 from material 5 is carried. out in known manner by moulding between opposing platens. Heat may be applied to assist in this process. Depending on the particular material choices made for lamination layers 1 , 2 and 3, and any adhesive layers therebetween, it may be that one or both pairs of lamination layers 1 , 2 and 3 are actually laminated together in the same process as forming of container 10 itself. Walls 14 and 20 are made sufficiently gentle in slope, and are blended sufficiently smoothly into surrounding parts, to avoid excessive damage to any of lamination layers 1, 2 and 3. In particular, lamination layer 1, when formed of blotting paper, has limited tearing strength and it is then desirable, in those parts of lamination layer 1 that in use lie adjacent to food, that lamination layer 1 wrinkle and crease rather than tear.

Arrow 21 in Figure 3 shows how upper section 12 can be rotated about hinge 213 until surface 25 of flange 24 of upper section 12 abuts surface 18 of flange 17 to close container 10. Container 10 is shown as having no air vents, although that is not to preclude the possibility of providing vents if desired.

When a pizza {not shown) is placed on surface 13 and container 10 is closed, steam or water vapour released from the pizza is at least partially absorbed and retained by inner layer 1 of material 5 from which container 10 is formed. Aluminium layer 2 aids in the thermal insulating function of container 10 and physically prevents any condensed water or oily or greasy material exuded by the pizza from passing through the lower section 11 to its external surface 26. Aluminium layer 2 also prevents migration of moisture absorbed by lamination layer 1 outward through the upper section 12. Two means are shown for holding container 10 in the closed condition, although either may be used alone if required or other closing means substituted. Firstly, upstanding from flange 17 are tapered pegs 28 (formed integrally with the remainder of container 10) that, when upper section 12 is closed over lower section 11 enter cooperating holes 29 in flange 24 and wedge there. Any tendency to tearing of lamination layer 1 during manufacture of container 10 is less important in pegs 28 than in the food- adjoining parts of lamination layer 1.

Secondly, bonded to flange surfaces 18 and 25 are mating areas 30 of a "cohesive" material. A cohesive material here means a material (contact- type adhesive) that sticks to another cohesive material (generally itself) when brought into contact therewith, but not to other materials. These materials are available commercially, and can have the property that the mutually adhering areas are able to be released from, and re-adhered to, each other several times. Thus when container 10 is closed by bringing surfaces 18 and 25 into abutment, areas 30 adhere to each other to hold container 10 closed, releasably and preferably re-sealably.

It will be readily apparent that hinge 213 is not necessary and could be omitted, leaving the upper and lower portions 11 and 12 as separate parts. Thfe use of material 5 in such a two-part food container (not shown) is also advantageous.

Figure 4 shows a further container 40 according to the invention. Container 40 is formed in one piece from the laminated material 5, with lamination layer 1 inward and lamination layer 3 outward when the container 40 is closed, and is shaped to accommodate more compactly-shaped foods (eg roast chicken or fish and/or chips) than pizza. Except for this shape, container 40 is in its function substantially similar to container 10. It has a lower section 41 in which the food can be placed and an upper lid section 42, lower and lid sections 41 and 42 being functionally similar to lower and upper sections 11 and 12 of container 10. Sections 41 and 42 are (optionally) hinged together at an integral hinge 46 and can be closed upon each other, clamshell-fashion as indicated by arrow 47. Cohesive areas 43 are provided (similar to areas 30 of container 10) together with pegs 44 and cooperating holes 45 (similar to pegs 28 and holes 29 of container 10). In use, container 40 also is adapted to slow the cooling of food placed therein, with in addition moisture (steam or water vapour) and greasy or oily exudates coming from the food being absorbed and retained in the inner lamination layer 1. Figure 5 shows still another thermally insulating container 50. Container 50 is formed from a material 75 that is another embodiment of a laminated material according to the invention.

Figure β is a cross-sectional view of a portion of laminated material 75, which unlike material 5 is non-rigid. Material 75 has four lamination layers, 71 - 74, of which lamination layer 71 is made the innermost when material 75 is used in manufacture of a container. Lamination layers 71 and 72 are the same as lamination layers 1 and 2 of material 5, and are as described above in the discussion of material 5.

Lamination layer 73 is (like layer 3 of material 5) a thermally insulating layer, but is flexible. It is formed of so-called "bubble-pack" material, i.e. flexible plastics sheet material having a set of distinct closed, air-filled cells, so as to provide an insulating function.

Lamination layer 74 is outermost in use of material 75 in containers and is optional. Lamination layer 74 comprises a flexible sheet material formed from high density polyethylene (HDPE) fibres, as available for example under the trade name "Tyvek" from E.I. du Pont de Nemours and Company. This material is very strong and resistant to tearing.

As an alternative, given that both lamination layer 72 and lamination layer 73 form moisture/grease barriers, a paper-type layer 74 based on cellulose fibres may be used.

Container 50 is in the form of an envelope or bag, formed as follows. A sheet of laminated material 75 that is rectangular (save for two opening tabs 53 and 54) is first folded on opposing sides to form parallel edges 51 and 52, and is then folded transversely to the initial folds to form a folded edge 55. The folding is such that inner lamination layer 71 of material 75 is on the inside of folded edge 55. These operations define four surfaces 56, 57, 58 and 59 on outer layer 4 of material 5. Surfaces 56 and 57 and surfaces 57 and 58 are then bonded together using a suitable adhesive (not shown) to define an envelope-type container. An adhesive strip 60 is provided to enable edges 61 and 62 to be sealed together, thus closing container 50, and can be torn away (by first grasping a tab 63) to open container 50.

Figures 7 and 8 show another food container 100 made according to the invention. Container 100 is in the form of an approximately square flat- sided box proportioned to be suitable for pizza (not shown), but its proportions may be modified as required to suit other food products.

Figure 9 shows in section a portion 105 of a laminated material from which container 100 is made. Portion 105 has three layers 101 - 103, the layers 101 - 103 being as follows:

1. A first layer 101 that is innermost when the container 100 is formed and that is adapted to absorb and retain water (released as steam or water vapour from the contained food or that condenses within container 100) and to at least some degree grease or oily material exuded from the contained food. As in the case of layer 1 , layer 101 may be formed from blotting or other suitably absorbent paper. A suitable type is cotton-fibre- based blotting paper of about 250g/sq. meter basis weight, able to absorb water to a level of about 120 ml/sq. meter.

2. A second layer 102, impervious to flow of water and oil- and grease-type exudates, of aluminium foil. (Layer 102 (could be plasticized and container a layer a foil.) A suitable thickness of a simple foil layer 102 has been found to be of 0.020 inch (0.5mm).

3. A third layer 103 of so-called corrugated cardboard. This material itself comprises three components, namely paper facing layers 106 and 107 and a corrugated internal paper layer 108. Layer 108 is glued to facing layers 106 and 107 where layer 108 contacts those layers, eg at locations 109 and 110 shown in Figure 9. Material such as layer 103 is well-known in the packaging art, Inexpensive, and has a degree of rigidity and damage tolerance such that it is much used in boxes and cartons. The layers generally comprise cellulosic material, which may be of recycled. Starch type glue is commonly used. A suitable type of corrugated cardboard for pizza containers at least is so called "B-flute" type, which is about 3mm thick.

Layers 1 and 2 are held together over at least a part of their facing surfaces by adhesive (not shown) of any suitable type, as are layers 2 and 3. It is possible to coat layer 102 with a heat-activated adhesive on both sides before it is placed in contact with layers 101 and 103, and subsequently apply heat to activate the adhesive.

Figure 10 shows a flat blank 111 from which container 100 can be formed. Blank 111 is of known type and its design is not of the essence of the present invention. However it is of a type that is believed to be particularly suitable and convenient for use with the laminated material of the present invention. In Figure 10, solid lines, rendered as shown by sample line 112, represent edges of, or cuts in, the blank 111, and lines or parts of lines rendered as shown by sample line 113 represent simple folds. Line sections rendered as shown by sample line 114 are fold lines but also have perforations to ease folding. Blank 111 includes elongate holes 115 and 116 which in the completed container 100 receive tabs 117 and 118 respectively. Similarly, elongate holes 119 and 120 receive tabs 121 and 122 respectively. Hole 123 is a finger hole for opening container 100 and also acts as a vent. Hole 123 is optional. Holes 124 and 125 are vents and are also optional. Section 126, in the completed container 100, is the base of container 100, on whfich in use the food sits, and section 127 is positioned over the food as part of a lid 128 of container 100. Sections 129 form sidewalls of bottom part 130 and sections 131 form sidewalls of lid part 132.

Double fold lines 133 enable a front wall 134 of bottom part 130 to be formed with tabs 135 between sections 136 and 137. Double fold lines 138 enable a front wall 139 of lid part 140 to be formed with tabs 141 and 142 between sections 143 and 144. A container 100 having such double fold lines as 133 and 138 is sometimes referred to as a "double fold" type. Container 100 does not greatly stress the normally comparatively fragile layer 101 , so is particularly suitable for use with such a layer 101.

In practice, material as shown in Figure 9 is prepared and then formed into blanks as shown in Figure 10, for subsequent folding into container 100 on an as-required basis.

Figure 11 shows in section a portion 145 of an alternative layered material which could be used in a container such as container 100, as an alternative to material 105 described above. In material portion 145, the following components are present:

1. A moisture-absorbent first layer 146, corresponding in function to layer 101, and that is innermost in use of the material in a food container;

2. An impervious foil (or foil-containing) layer 147;

3. A third layer 148 that itself comprises a facing paper layer 149 and secured thereon a corrugated paper layer 150. In essence, layer 148 is the same as layer 103, but without facing layer 106. Layers 146 and 147 are adhesively secured to each other and layers

147 and 148 are adhesively secured to each other at locations 200. Layers 146 and 147 together act in the same way as layer 106 of layer 103 so that the material shown in Figure 11 still has a degree of rigidity that with suitable materials and dimensional choices may be made sufficient for its intended use as a food container.

As an alternative to making folded containers such as container 100 from blanks 111 consisting entirely of laminated materials of the type shown in Figure 9, it is possible to make such a blank in which one or two of the three layers are applied only over part of the blank. A blank (not shown) may be made that is the same as blank 111 except that its whole area is made from the corrugated cardboard 103, but absorbent layer 101 and foil layer 102 are applied subsequently and only to the large sections 126 and (optionally but preferably) 127. Although more complex, this approach does reduce the amount of foil and absorbent material required.

It is also possible (not shown) to apply the foil to the whole blank, but to only apply individual pieces of absorbent material subsequently in this way, so that the materials saving is in the absorbent material only.

It will be appreciated that although specific preferred materials have been disclosed above as suitable for lamination layers 1 , 2, 3, 71 , 72 and 73, and 101 - 103, other materials may be substituted in appropriate circumstances. Thus, for example, lamination layer 1 (or 101 or 71) could be, instead of a paper-type material, an open-cell foamed plastics material (eg foamed polyethylene) acting as a "sponge" to absorb and hold moisture. A thickness of 3mm could be appropriate. Some other possibilities for lamination layer 1 or 71 or 101 are felt and absorbent natural fibres such as compressed coconut fibre or rice husk material. Generally, a cellulose based board- or paper —type material that is reasonably absorbent of moisture may be used. Where the container is to be rigid, as in the cases of containers and 100, the moisture absorbent layer (1 or 101 ) could be made of papier mache of the type sometimes used for fluid filter elements.

For lamination layer 2 (or 72 or 102) foils of metal other than Aluminium or Aluminium-containing alloy may be used. Foil secured to or embedded in plastics sheet material other than "Mylar" may also be used. For lamination layer 3 (or 103), where some rigidity is required, a simple papier mache or paper board layer may be used instead of a paperboard/plastic combination as described above. Another possibility is a corrugated cardboard layer of the type used in cardboard shipping cartons, file boxes and the like. Still another possibility is an extruded plastics layer of the known type having elongate parallel air cells between face sheets, the cells being separated by parallel walls extending between the face sheets. Lamination layer 3 (or 103) may have a printable layer or membrane on its outer surface. Where lamination layer 3 (or 103) is of paperboard with more than one plastics layer, one of those plastics layers may be an outside layer and one may abut lamination layer 2. Printed and formable corn starch plastic in sheet form and foamed polyolefins (eg polypropylene or polyethylene) are other possibilities.

For lamination layer 73, a thermally insulating material with flexibility is required. As an alternative to "bubble pack" material, this could be a suitable fabric, or a mat of oellulosic or other flexible insulating fibre. Such a mat of cellulosic or other flexible fibre becomes practicable when supported externally by a lamination layer 74 with some rigidity. The comments above in relation to lamination layer 3 apply to layer 74. At least some of these alternative materials are more expensive than those described earlier, and in many applications, this will be critical.

It should be noted that it is known in the art to form or mould container parts formed of corrugated cardboard, provided care is taken to design those parts and/or to score, or otherwise pretreat, the material so that the forming does not lead to failure (eg by tearing) of the material. Accordingly, a formed container generally similar to that shown in Figures 2 and 3, but made with laminated materials as shown in Figure 9 or 11 , is also within the scope of the present invention as an alternative to the folded container 100.

Many other variations will suggest themselves to persons skilled in the art that are within the scope of the invention.

Claims

1. A laminated material for use in making thermally insulating containers for items of food comprising, in order:

(d) a first lamination layer, comprising a layer of a material adapted to absorb and retain moisture;

(e) a second lamination layer, impervious to movement of fluids therethrough and comprising a layer of metallic foil; and

(f) a third lamination layer, comprising a layer ef thermally insulating material,

the first and second layers being secured to each other over at least a portion of their adjoining surfaces and the second and third layers being secured to each other over at least a portion of their adjoining surfaces.

2. A laminated material according to claim 1 wherein the first lamination layer is adapted to absorb and retain in addition to water at least a proportion of greasy or oily foodstuff exudates.

3. A laminated material according to claim 1 or 2 wherein the first lamination layer comprises a layer of absorbent paper.

4. A laminated material according to claim 3 wherein the absorbent paper comprises blotting paper formed using cotton fibres.

5. A laminated material according to claim 3 or 4 wherein the absorbent paper has a basis weight of about 250 gm/sq. m.

6. '" A laminated material according to any one of claims 3 to 5 wherein the absorbent paper is capable of absorbing water to a level of approximately 120 ml/sq. m.

7. A laminated material according to any one of claims 1 to 6 wherein the second lamination layer comprises a layer of aluminium or of an alloy including aluminium.

8. A laminated material according to claim 1 wherein the metallic foil has a thickness of about 0.5mm (0.020 inch).

9. A laminated material according to any one of claims 1 to 8 wherein the third lamination layer comprises a paperboard layer.

10. A laminated material according to claim 9 wherein the third lamination layer comprises at least one paperboard layer and at least one layer of, or at least partially comprising, a polymer plastics material.

11. A laminated material according to claim 10 wherein the or a said polymer plastics material layer lies adjacent to the second lamination layer and wherein bonding of the second and third lamination layers is by that polymer plastics material.

12. A laminated material according to any one of claims 1 to 8 wherein the third lamination layer comprises a layer of flexible sheet material.

13. A laminated material according to any one of claims 1 to 8 wherein the third layer is itself layered and comprises a paper layer and secured thereto a layer of corrugated paper, and wherein the layer of corrugated paper is adhesively secured to the second lamination layer.

14. A laminated material according to any one of claims 1 to 8 wherein the third layer is itself layered and comprises two paper layers and adhesively secured between said two paper layers a third layer comprising corrugated paper, and wherein one of said two paper layers is secured adhesively to the second lamination layer.

15. A food container having a food-holding part with a floor and walls extending peripherally around and upwardly from the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein the food container is formed from a laminated material according to any one of claims 1 to 14 and the first lamination layer of said laminated material faces inwardly of the said internal space.

16. A food container according to claim 15 wherein the food-holding part and the lid portion are formed integrally with each other, and hingedly connected to each other.

17. A food container according to claim 15 formed from a flat blank of said laminated material.

18. A food container having a food-holding part with a floor and walls extending peripherally around and upwardly from the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein a first portion only of said food container comprises a laminated material according to any one of claims 1 to 14 and wherein a further portion comprises an integral extension of the third lamination layer of said first portion.

19. A food container having a food-holding part with a floor and walls extending peripherally around and upwardly from the floor, and a lid part positionable over the food-holding part to define a substantially enclosed internal space for a food item, wherein a first portion only of said food container comprises a laminated material according to any one of claims 1 to 14 and wherein a further portion comprises integral extensions of the second and third lamination layers of said first portion said integral extensions being themselves secured adhesively to each other.

20. A method for forming a food container including the step of pressing and forming a piece of a laminated material according to any one of claims 1 to 14 between opposing shaped platens, preferably with additional application of heat through the platens.

21. A method for forming a food container including the steps of preparing a flat blank of laminated material according to any one of claims 1 to

14, and forming the food container from the blank by manipulation that includes folding of the blank.

22. A method for forming a laminated material according to any one of claims 1 to 14 including the steps of firstly placing between each adjacent pair of said lamination layers a quantity of material that on application of heat adheres to both of the lamination layers of each pair and of secondly applying heat to said pairs whereby to bind said pairs of lamination layers together.