GB2598282A

GB2598282A - Thermally insulating packaging

Info

Publication number: GB2598282A
Application number: GB2010031.9A
Authority: GB
Inventors: Andrew Midgley Stephen; Mark Baron John; Marsden Ian
Original assignee: John Cotton Group Ltd
Current assignee: John Cotton Group Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2022-03-02
Anticipated expiration: 2040-06-30
Also published as: GB202010031D0; GB2598282B

Abstract

Thermally insulating packaging 100 comprises an arrangement of cellulosic paper layers sewn together with a thread 130. The layers include one or several inner paper layers 110 between first and second outer paper layers 120, and each outer layer has a greater areal density than each inner layer. Preferably, each outer layer also has a greater volumetric mass density than each inner layer. The stitching may go along at least two opposed edges of the packaging. The inner layer may be pleated, and may have an inner paper assembly provided between the first and second outer layers, comprising the pleated inner layer between first and second facing inner paper layers adjacent opposed faces of the pleated inner paper layer. A method of manufacturing the packaging comprises forming the arrangement of cellulosic paper layers and sewing them together with a thread.

Description

THERMALLY INSULATING PACKAGING

TECHNICAL FIELD

The present invention relates to thermally insulating packaging, and more particularly, but not exclusively, to a thermally insulating packaging for use in the storage and transport of foodstuffs, horticultural products and pharmaceuticals.

BACKGROUND

Thermally insulating packaging is used in transporting chilled foodstuffs, pharmaceuticals, heated foodstuffs, and other temperature sensitive products. Users may require to maintain the temperature of the chilled goods below 8°C for 24 to 48 hours, when exposed to particular ambient conditions (e.g. 24°C). In use, the chilled goods are commonly enclosed within the thermally insulating packaging with an ice pack.

Current thermally insulating packing is commonly made with a high percentage of polyester fibres, e.g. recycled polyethylene terephthalate (rPET) from recycled plastic bottles. The fibres may be bound by use of binders, and enclosed within a sheet polyethylene bag. Such products are often not readily recyclable with current curb-side recycling, and unfortunately is commonly disposed of through household waste, for landfill.

SUMMARY OF THE DISCLOSURE

According to a first aspect there is provided a thermally insulating packaging comprising an arrangement of cellulosic paper layers sewn together by stitching with a thread, wherein the cellulosic paper layers comprises one or a plurality of inner paper layers between first and second outer paper layers, and each of the outer paper layers has a greater areal density than each inner paper layer.

According to a second aspect there is provided a method of manufacturing thermally insulating packaging comprising an arrangement of cellulosic paper layers sewn together by stitching with a thread, wherein the cellulosic paper layers comprises one or a plurality of inner paper layers between first and second outer paper layers, and each of the outer paper layers has a greater areal density than each inner paper layer, the method comprising: forming the arrangement cellulosic paper layers; and sewing together the arrangement of cellulosic paper layers with the thread.

The areal mass density of the outer paper layers may be at least 33% greater than the areal mass density of the inner paper layers. The areal mass density of the outer paper layers may be at least 50% greater than the areal mass density of the inner paper layers. The areal mass density of the outer paper layers may be at least 66% greater than the areal mass density of the inner paper layers. The areal mass density of the outer paper layers may be at least 100% greater than the areal mass density of the inner paper layers.

The areal density of the inner paper layers may be 15 to 30 g/m2. The areal density of the inner paper layers may be 18 to 25 g/m2.

The areal density of the outer paper layers may be 40 to 90 g/m2. The areal density of the outer paper layers may be 50 to 80 g/m2.

Each of the outer paper layers may have a greater volumetric mass density than each inner paper layer. The volumetric mass density of the outer paper layers may be at least 25% greater than the volumetric mass density of the inner paper layers. The volumetric mass density of the outer paper layers may be at least 50% greater than the volumetric mass density of the inner paper layers. The volumetric mass density of the outer paper layers may be at least 100% greater than the volumetric mass density of the inner paper layers The volumetric mass density of the inner paper layers may be 200 to 400 kg/m'.

The volumetric mass density of the outer paper layers may be 500 to 1000 kg/m3.

The stitching may extend along at least two opposed edges of the thermally insulating packaging.

The thermally insulating packaging may be a bag in which, the arrangement of cellulosic paper layers is folded into a folded configuration, and stitching retains the plurality of cellulosic paper layers in the folded configuration.

The stitching may extend along each edge of the thermally insulating packaging.

The inner paper layer may be a pleated inner paper layer having a pleating pattern.

An inner paper assembly may be provided between the first and second outer paper layers, comprising the pleated inner paper layer between first and second facing inner paper layers adjacent opposed faces of the pleated inner paper layer.

A plurality of pleated inner paper layers may be provided between the first and second outer paper layers, and wherein there may be an angular offset between the pleating patterns of successive pleated inner paper layers.

The inner paper layer may be an embossed inner paper layer that is embossed with an embossing pattern.

An inner paper assembly may be provided between the first and second outer paper layers, comprising a plurality of embossed inner paper layers in which there is a translational offset between the embossing patterns of successive embossed inner paper layers.

An inner paper assembly may be provided between the first and second outer paper layers, comprising a plurality of embossed inner paper layers in which there is an angular offset between the embossing patterns of successive embossed inner paper layers.

An inner paper assembly may be provided between the first and second outer paper layers, comprising a plurality of embossed inner paper layers in which there is inversion of successive embossed inner paper layers.

The inner paper assembly may be handled in the same manner as an individual paper layer, during construction of the thermally insulating packaging, e.g. the thermally insulating packaging may be constructed by successively laying inner paper assemblies each comprising a plurality of inner paper layers, and is not limited to successively laying individual inner paper layers.

The angular offset may be 7° to 26°. The angular offset may be 12° to 18° The cellulosic paper layers may comprise a plurality of inner paper layers, each having sheer-induced non-planar irregularities. The cellulosic paper layers may comprise a plurality of inner paper assemblies, each having sheer-induced non-planar irregularities.

The cellulosic paper layers may comprise at least 15 inner paper layers between the first and second outer paper layers.

The plurality of cellulosic paper layers may be sewn together by stitching with a linear stitch density of 100 to 250 stitches/m.

The thread may be a cellulosic fibre thread.

The inner paper layer may each have an areal density of 15 to 30 g/m2. The inner paper layer may each have an areal density of 18 to 25 g/m2.

The outer paper layers may each have an areal density of 40 to 90 g/m2. The outer paper layers may each have an areal density of 50 to 80 g/m2.

The cellulosic paper layers may comprise cellulosic fibres from wood pulp. The cellulosic paper layers may consist of cellulosic fibres from wood pulp (e.g. substantially pure wood pulp). The cellulosic wood fibres may be from recycled paper.

The method may comprise layering the plurality of inner paper layers by a cross-lapping process.

The method may comprise pleating the inner paper layer with a pleating pattern by passing the inner paper layer through a pair of crimping rollers.

DESCRIPTION OF THE DRAWINGS

Examples are further described hereinafter with reference to the accompanying drawings, in which: * Figure 1A shows thermally insulating packaging being filled with exemplary chilled foodstuffs; * Figure 1B shows a cross-sectional view through the thermally insulating packaging of Figure 1A, along line X-X;

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* Figure 10 shows a stitched blank during the manufacture of a thermally insulating packaging; * Figure 1D shows a thermally insulating packaging formed by folding and further stitching the blank of Figure 10; * Figure 1E and 1F illustrates further thermally insulating packaging; * Figure 2 illustrates a cross-laying process; * Figure 3 shows the formation of the three-ply assembly with a pleated core; * Figure 4A shows a plan view of an embossing inner paper layer having an embossing pattern; * Figure 4B shows a cross-sectional view through the embossed inner paper layer of Figure 4A, along line Y-Y; and * Figures 4C to 4E show arrangements of successive embossed inner paper layers, in cross-sectional view.

DETAILED DESCRIPTION

Like reference numerals refer to like elements throughout. In the described examples, like features have been identified with like numerals, albeit in some cases having suffix letters; and typographical marks. For example, in different figures, 100, 100' and 100" have been used to indicate thermally insulating packaging, and 130A, 130B, 130C, 130D and 130E have been used to indicate stitching.

Figure 1A shows thermally insulating packaging 100 (e.g. a thermally insulating bag), being filled with exemplary chilled foodstuffs 190, and Figure 1B shows a cross-sectional view through the thermally insulating package along line X-X indicated in Figure 1A.

The thermally insulating packaging 100 is formed from an assembly of layers of cellulosic paper (e.g. each comprising cellulosic fibres from wood pulp, e.g. at least 90% cellulosic wood pulp fibres), in which one or more lighter-weight inner paper layers 110 are sandwiched between heavier-weight outer paper layers 120. The thermally insulating packaging 100 is sewn together by stitching 130 that passes through the inner and outer paper layers 110, 120.

The areal density of the inner paper layers 110 may be 15 to 30 g/m2, or 18 to 25 g/m2. The inner paper layers 110 may be a light-weight tissue grade of paper. The areal density of the outer paper layers 120 may be 40 to 90 g/m2. or 50 to 80 g/m2. The areal mass density of the outer paper layers 120 may be at least 33% greater than the areal mass density of the inner paper layers 110, and may be at least 50%, 66% or 100% greater than the areal mass density of the inner paper layers 110.

The volumetric mass density of the inner paper layers 110 may be 200 to 400 kg/m'. The volumetric mass density of the outer paper layers 110 may be 500 to 1000 kg/m3. The volumetric mass density of the outer paper layers 110 may be at least 25% greater than the volumetric mass density of the inner paper layers 110, and may be at least 50% or 100% greater than the volumetric mass density of the inner paper layers 110.

In the illustrated thermally insulating packaging 100, the inner paper layers 110 have an areal density of 22 g/m2, and the outer paper layers 120 have an areal density of 50 g/m2. The outer paper layers may be a light-weight kraft paper or paperboard (cardboard), which is more rigid that typical writing paper, whilst still able to flex and crease without fracture.

In use, chilled goods 190 (e.g. foodstuffs, horticultural products or pharmaceuticals) are placed into the thermally insulating package 100, e.g. with ice packs (not shown) to assist with regulating the temperature of the chilled goods. Condensation may develop on the exterior of chilled goods and any ice packs. The heavier-weight outer paper 120 provides a moisture barrier that protects the inner paper 110 from moisture damage when the thermally insulating package 100 is in use. Outer paper 120 with a higher volumetric mass density may have a more tightly packed fibre structure, which may better resist penetration by moisture, during use (e.g. 24 to 48 hours), relative to a thicker paper with the same areal mass density. Outer paper 120 with a higher areal mass density may resist penetration by moisture for longer. Additionally, the heavier-weight outer paper protects the inner paper from mechanical damage during in use.

The use of the protective heavier outer paper 120 enables the selection of lighter inner paper 110, which may have a less tightly packed fibre structure, which may have a greater flexibility and elasticity than paper with a higher volumetric mass density, and enables the use of a lower total weight of layers to provide a given level of thermal insulation.

As shown in Figure 10, during manufacture, a blank 102 of the required cellulosic paper layers is prepared to the required size, e.g. by cutting from a larger arrangement of layers, or by layering cellulosic paper layers of the required size.

To prepare the thermally insulating bag 100 illustrated in Figure 1A: * Stitching 130A, 130B is used in a first sewing step to sew together the cellulosic paper layers 110, 120 of the blank 102. The stitching may be adjacent at least one edge 104A of the blank 102, e.g. adjacent two opposed edges 104A, 104B of the blank 102, as shown in Figure 10.

* The blank 102, is folded over along a fold line F between two parts 102A, 102B, e.g. a fold line that is slightly offset from the mid-point between two opposed edges 104A, 104B, to overlap the majority of the two parts of the blank, whilst leaving an exposed flap 106, as shown in Figure 10, for use as a closure, e.g. by adhesive or adhesive label or tape.

* Further stitching 1300, 130D is used in a second sewing step to sew together the overlapping regions of the two parts 102A, 102B of the blank 102, to maintain the folded shape and to produce a bag, e.g. stitching adjacent to two further opposed edges 104C, 1040 of the blank 102, as shown in Figure 10.

Figure 1E illustrates a further thermally insulating packaging 100', which is in the form of a thermally insulating wrap, for wrapping around chilled items. As shown in Figure 10, during manufacture, a blank 102 of the required cellulosic paper layers is prepared to the required size, e.g. by cutting from a larger arrangement of layers, or by layering cellulosic paper layers of the required size.

To prepare the thermally insulating wrap 100' illustrated in Figure 1E, from the blank: * Stitching 130A, 130B is used in a sewing step to sew together the cellulosic paper layers 110, 120 of the blank 102. The stitching may be adjacent at least one edge 104A of the blank 102, e.g. adjacent each edges 104A, 104B, 1040, 1040 of the blank 102, as shown in Figure 1E.

Sewing together the assembly of paper layers enables the stitched regions 130 (e.g. adjacent edges) of the thermally insulating packaging 100 to maintain a significant degree of flexibility. The flexibility of the stitched regions 130 enhances the ability of the assembly of paper layers to conform more closely to the shape of chilled goods 190, in use, compared with an assembly of paper layers in which the successive layers are connected by adhesive. Flexible regions F that conform more closely to the chilled goods 190 reduces the volume of air gaps G between chilled goods and the assembly of paper layers through which convection currents may transport heat, especially next to any opening P for air flow from the exterior. Additionally, the flexibility of the stitched regions 130 enables an increased volume of chilled goods 190 to be enclosed by the thermally insulating packaging 100, e.g. increasing the useable volume of the illustrated bag.

The thread may be less than 1% of the mass of the thermally insulating packaging.

The thread may be a cellulosic fibre thread, e.g. cotton. The cellulosic fibre thread may be recycled through domestic paper recycling or composting. Alternatively, the thread may be polyester, or a mix of polyester and cellulosic fibres (e.g. a polyester-cotton blend).

By use of substantially only cellulosic paper and cellulosic thread, the assembled thermally insulating product may be recycled through domestic paper recycling or composting.

The stitching may have a linear stitch density of 100 to 250 stitches/m (approximately 3 to 6 stitches per inch). This range of linear stitch densities may enable the manufacture of robust thermally insulating packaging that resists water leakage and water penetration.

More closely spaced stitches may substantially weaken the paper layers, risking tearing, like a perforation, when the thermally insulating packaging is used. More closely spaced stitches may increase the transmission of water, through the cellulosic thread, into the inner paper layers, reducing the thermal insulation performance of the thermally insulation packaging.

More widely spaced stitches may enable water within a thermally insulating packaging to escape.

The stitching pattern may be a chain stitch. The stitching may be provided with a lock stitch.

The lock stitch reduces the risk of the stitching unravelling, to maintain the integrity of the thermally insulating packaging.

In the thermally insulating bag 100 illustrated in Figures 1A and 1D, one edge of the bag is provided by the fold of the layers of paper, without requiring stitching.

In some cases (e.g. thick assemblies of cellulosic paper layers), the thickness of the folded layers could lead to the layers bulging apart adjacent the fold, producing a small gap at the stitching, i.e. at the corresponding corners of the interior of the bag, through which water may leak.

Figure 1F illustrates an alternative bag 100", in which additional stitching 130" is provided, adjacent, but spaced apart from and extending along the fold line F. The additional stitching 130E may improve water containment at the corresponding interior corners of the bag 100".

Advantageously, by construction from cellulosic materials (cellulosic paper and cellulosic thread) the thermally insulating packaging may be recycled through domestic paper recycling or domestic composting, providing a lower environmental of footprint than existing rPET thermally insulating packaging, both in manufacturing and in end of life disposal.

The thermally insulating packaging 100, 100' may be formed with a plurality of lighter-weight inner paper layers 110 sandwiched between the heavier-weight outer paper layers 120, providing a greater level of thermal insulation than where only a single inner paper layer is used between the outer paper layers. The plurality of lighter-weight paper layers 110 may be formed by laying separate sheets in a stack, e.g. layering separate, continuously fed ribbons from respective rolls of paper. Alternatively, the plurality of lighter-weight paper layers 110 may be formed from a common, continuously fed ribbon by a cross-laying process.

Figure 2 illustrates a cross-laying process in which a ribbon 110' of lighter-weight paper is fed to a cross-laying mechanism 180 (e.g. a system of belts, running around rollers and forming a reciprocating ribbon laying head). The cross-laying mechanism 180 lays the ribbon onto an underlying conveyor belt 182, with a ribbon laying head that reciprocates R across the conveyor belt. The conveyor belt 182 moves T transversely (e.g. perpendicularly) to the reciprocation direction of the laying head. The laying head overlays the feed of ribbon 110' in a reciprocating pattern, producing multiple layers in a pleated folded arrangement.

However, as the laying head lays the feed of ribbon 110', the conveyor belt 182 simultaneously draws the laid ribbon away from the laying head, so that each layer of ribbon is laid at a divergent angle A to the preceding layer (and at a divergent angle to the reciprocation direction S. e.g. at an angle of A/2 for a symmetrical laying arrangement), which it does not fully overlap, causing the folded ribbon 110" to be distributed along the conveyor belt in a zigzag pattern.

During cross-laying, the transverse movement T of the conveyor belt 180, relative to the reciprocation direction R of the ribbon laying head of the cross-laying mechanism 180 produces sheer forces in the ribbon 110', as it is deposited. The sheer forces introduce non-planar irregularities in the deposited ribbon 110", as shown in Figure 1B, enhancing the trapping of air between the successive paper layers. Cross-laying the inner paper layers may enable a particular thermal insulation performance to be provided with fewer paper layers, reducing the environmental footprint and total weight of the thermally insulating packaging.

The number of layers of the folded ribbon 110" formed at each location, the divergent angle A between successive layers, and the sheer forces in the ribbon 110' as it is deposited, are each dependent upon the ribbon feed speed, the reciprocation speed, and the conveyor belt speed. The divergent angle A (angular offset) between successive layers may be 7° to 26°, and may produce the sheer force induced non-planar irregularities. The illustrated divergent angle A is in the range 12° to 18°. Layers of ribbon that are laid by a cross-laying process are sequentially inverted, as well as being laid with a divergent angle. In the case that the ribbon is patterned (e.g. a feed of pleated or embossed ribbon), the inverted patterns diverge from being anti-parallel by the divergent angle A. The heavier, outer paper layers 120 may be provided on either face of the plurality of lighter-weight paper layers 110 may be after the plurality of lighter-weight papers has been formed. Alternatively, the plurality of lighter-weight papers may be formed onto one of the heavier-weight outer paper layers 120. Where the plurality of lighter-weight paper layers 110 are arranged by cross-laying, a heavier-weight outer paper layer 120 may be provided onto the conveyor belt 182, and the lighter-weight paper layers 110 may be laid onto the heavier-weight outer paper layer 120.

The thermal insulation performance of the thermally insulating packaging may be enhanced by the use of one more or more inner paper layers 110 that are pleated (perpendicular to the plane of the layer) or embossed, to increase the volume of air trapped between the layers of cellulosic paper.

Pleated inner paper layers trap air within their folds. This may enable a particular thermal insulation performance to be provided with fewer paper layers, reducing the environmental footprint and total weight of the thermally insulating packaging.

Where the pleated inner paper layers are sufficiently strong to be able to maintain their pleated shape during manufacturing. One or more individual pleated paper layers may be used, which may be flat-laid or cross-laid.

Alternatively, pleated inner paper layers may be assembled into a multi-ply assembly (e.g. a three-ply assembly), between flat inner paper facing layers, with air trapped between the pleated and each of the flat inner paper facing layers. Friction between the edges of the pleats and the paper facing layers maintains the shape of the pleats, and reduces the risk of the pleats collapsing during manufacturing (handling, e.g. passing through a cross-laying mechanism) and use, enabling the use of lighter weight inner paper layers, with a lower environmental footprint, than would otherwise be required to maintain the pleats during manufacturing and use.

Figure 3 shows the formation of the three-ply assembly 110A with a pleated core. Three ribbons of inner paper 110' are fed through a system of rollers, with crimping rollers CR producing a pleated pattern in the middle ribbon to produce a ribbon of pleated inner paper 110P, which is received between ribbons of facing inner paper. The three-ply assembly 110A is them handled as a single sheet in forming the assembly of cellulosic paper layers in the thermally insulating packaging. For example, the three-ply assembly 110A may be cross-lapped by a cross-lapping mechanism.

A three-ply assembly of a single pleated inner paper layer between facing paper layers has been described. However, other assemblies of inner paper layers may also be used, having more than one pleated inner paper layer, e.g. a five-ply or seven-ply assembly respectively with two or three pleated inner paper layers between flat inner paper facing layers, and with successive pleated inner paper layers separated by flat inner paper separation layers.

Embossed inner paper layers trap air within their pockets formed by the embossing pattern. This may enable a required thermal insulation to be provided with fewer paper layers, reducing the environmental footprint and total weight of the thermally insulating packaging.

The embossed inner paper layers retain the embossing, including during manufacturing and use. Figure 4A shows an exemplary embossed inner paper layer 110E embossed with a repeating pattern of elongate diamonds, defined by two intersecting sets of parallel ridges R extending continuously across the embossed inner paper layer, and Figure 43 shows a cross-sectional view along line Y-Y. The illustrated sets of ridges R intersect with an acute angle of approximately 600.

One or more embossed inner paper layers may be used. VVhere a plurality of embossed layers 110E are used, they may be flat-laid or cross-laid. To prevent intermeshing of the embossing patterns of sequential embossed layers 110E, they may be arranged with one or more of: a translational offset D (parallel to the plane of the layer) between the embossing patterns of successive embossed inner paper layers, as shown in Figure 4C; an angular offset between the embossing patterns of successive embossed inner paper layers, as shown in cross-sectional view in Figure 40; and, inversion of successive embossed inner paper layers, as shown in Figure 4E. Sequential embossed cross-laid layers will be both angularly offset and inverted.

The illustrated embossing pattern has raised ridges R extending continuously across the inner paper layer. However, other patterns may be used, which trap air between successive layers. For example, the embossed paper layers may have a pattern of raised ridges extending across the paper by the same or greater length as the perpendicular spacing between parallel ridges.

The thermally insulating packaging has been described for use in maintaining the temperature of chilled product. However, the thermally insulating packaging may also be used in maintaining the temperature of heated products, e.g. takeaway (takeout) food products.

The figures provided herein are schematic and not to scale Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. 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. The invention is not restricted to the details of any foregoing embodiments. 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.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS1. Thermally insulating packaging comprising an arrangement of cellulosic paper layers sewn together by stitching with a thread, wherein the cellulosic paper layers comprises one or a plurality of inner paper layers between first and second outer paper layers, and each of the outer paper layers has a greater areal density than each inner paper layer.
2. The thermally insulating packaging of claim 1, wherein each of the outer paper layers has a greater volumetric mass density than each inner paper layer.
3. The thermally insulating packaging of claim 1 or claim 2, wherein the stitching extends along at least two opposed edges of the thermally insulating packaging.
4. The thermally insulating packaging of claim 1, claim 2 or claim 3, wherein the thermally insulating packaging is a bag, the arrangement of cellulosic paper layers is folded into a folded configuration, and stitching retains the plurality of cellulosic paper layers in the folded configuration.
5. The thermally insulating packaging of claim 1, claim 2 or claim 3, wherein stitching extends each edge of the thermally insulating packaging.
6. The thermally insulating packaging of any preceding claim, wherein the inner paper layer is a pleated inner paper layer having a pleating pattern.
7. The thermally insulating packaging of claim 6, wherein an inner paper assembly is provided between the first and second outer paper layers, comprising the pleated inner paper layer between first and second facing inner paper layers adjacent opposed faces of the pleated inner paper layer.
8. The thermally insulating packaging of claim 6 or claim 7, wherein a plurality of pleated inner paper layers is provided between the first and second outer paper layers, and wherein there is an angular offset between the pleating patterns of successive pleated inner paper layers.
9. The thermally insulating packaging of any preceding claims 1 to 5, wherein the inner paper layer is an embossed inner paper layer that is embossed with an embossing pattern.
10. The thermally insulating packaging of claim 9, wherein an inner paper assembly is provided between the first and second outer paper layers, comprising a plurality of embossed inner paper layers in which there is one or more of: a translational offset between the embossing patterns of successive embossed inner paper layers; an angular offset between the embossing patterns of successive embossed inner paper layers; and inversion of successive embossed inner paper layers.
11. The thermally insulating packaging of claim 8 or claim 10, wherein the angular offset is 7° to 26°.
12. The thermally insulating packaging of any preceding claim, wherein the cellulosic paper layers comprise a plurality of inner paper layers or inner paper assemblies each having sheer-induced non-planar irregularities.
13. The thermally insulating packaging of any preceding claim, wherein the cellulosic paper layers comprise at least 15 inner paper layers between the first and second outer paper 20 layers.
14. The thermally insulating packaging of any preceding claim, wherein the plurality of cellulosic paper layers are sewn together by stitching with a linear stitch density of 100 to 250 stitches/m.
15. The thermally insulating packaging of any preceding claim, wherein the thread is a cellulosic fibre thread.
16. The thermally insulating packaging of any preceding claim, wherein the inner paper layer or sub-layer has an areal density of 15 to 30 g/m2, and the outer paper layers each have an areal density of 40 to 90 g/m2.
17. The thermally insulating packaging of any preceding claim, wherein the cellulosic paper layers comprise cellulosic fibres from wood pulp.
18. A method of manufacturing thermally insulating packaging comprising an arrangement of cellulosic paper layers sewn together by stitching with a thread, wherein the cellulosic paper layers comprises one or a plurality of inner paper layers between first and second outer paper layers, and each of the outer paper layers has a greater areal density than each inner paper layer, the method comprising: forming the arrangement cellulosic paper layers; and sewing together the arrangement of cellulosic paper layers with the thread.
19. The method of claim 18, comprising layering the plurality of inner paper layers by a cross-lapping process.
20. The method of claim 18 or claim 19, comprising pleating the inner paper layer with a pleating pattern by passing the inner paper layer through a pair of crimping rollers.