Kit of parts configured to form a corner piece, and a corner piece

Abstract

The disclosure relates to a kit of parts and to a corner piece both comprising: a paper-based blank, and 5 a blank of a cellulose-based low-density material, wherein the paper-based blank comprises a first portion, a second portion, and a connecting panel, wherein the first portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality of inside 10 surfaces of said corner piece, wherein the second portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality outside surfaces of said corner piece, wherein the first portion and the second portion are foldably connected to 15 each other by the connecting panel, wherein the blank of a cellulose-based low-density material comprises three panels folded relative to each other and to positioned between the first portion and the second portion of the paper-based blank such that each of the three panels of the blank of a cellulose-based low-density material is positioned between a 20 respective set of a main panel of the first portion and an associated main panel of the second portion. Elected for publication: Fig 2

Description

[0001] KIT OF PARTS CONFIGURED TO FORM A CORNER PIECE, AND A CORNER PIECE

[0002] Field of invention

[0003] The invention relates to kit of parts configured to form a corner piece. The invention also relates to a corner piece. The corner piece is preferably configured to protect a corner. The corner piece may e.g., be located inside a corner of a package or box, such as a paper-based package or box, and form a protective corner piece between goods and the corner of the package or box.

[0004] Technical Background

[0005] A corner is typically an intersection point of three planes, which often are orthogonally positioned in relation to each other. A corner is thus often more vulnerable than other parts of a product and often therefore need to be protected to a greater extent than other parts of the product.

[0006] When designing a corner piece configured to provide protection, the designer typically takes a plurality of design criteria in consideration. The corner piece should, e.g., be designed such that it makes efficient use of material, is easy to prepare for use, is space efficient during transport and storage, provides a strong structure during use, and provide good shock absorbing properties as well as load distributing properties. During use the corner piece should be able to protect a corner of a product from damage. Currently, corner protection pieces are typically made from plastic materials, such as expanded polystyrene (EPS). When the corner protection pieces are of a pre-formed design, they take up unnecessary space during delivery and storage. Moreover, the use of plastic pieces makes recycling comparably more cumbersome since the packages often are formed of paper and thereby there are two different kinds of materials to be recycled. Protective corner pieces may also be formed of corrugated board. However, it is often difficult to obtain sufficient protective properties using corrugated board unless the corner piece is formed by a complex folding of a complex blank of corrugated board. Often it also requires the use of glue or the like to keep the corner piece of corrugated board in the intended position. Thus, corrugated board corner protection pieces typically become complex and increases the overall packing time.

[0007] In DE2064620A1 there is disclosed a corner piece made from a plastic foam. It is disclosed that the plastic foam is provided with a cover layer to form a blank from a foam layer composite, which is cut and then bent to protect corners or edges. It is disclosed that the cover layer may be of corrugated cardboard and that the cover layer may be provided on both sides or on only one side of the plastic foam. If there is a cover layer on both sides, one of the cover layers are cut through as well as the plastic foam, such that the composite may be folded about the remaining cover layer. However, it may be noted that the cutting and folding will create inherent weak spots of the corner piece thereby reducing its functionality as protective corner.

[0008] Thus, there is still a need for a corner piece adequately addressing at least some of the design criteria mentioned above.

[0009] Summary of invention

[0010] It is an object of the invention to provide a solution concerning how to provide a corner piece which addresses at least some, preferably all, of the problems indicated above and which also addresses at least some, preferably all, of the design criteria stated above. Thus, it is an object of the invention to provide a solution concerning how to provide a corner piece which should, e.g., be designed such that it makes efficient use of material, be easy to prepare for use, be space efficient during transport and storage, be capable of providing a strong structure during use, be capable of providing good shock absorbing properties as well as load distributing properties, and during use be able to protect a corner of a product from damage.

[0011] This object has been achieved by a kit of parts configured to form a corner piece, the kit of parts comprising: a paper-based blank, and a blank of a cellulose-based low-density material, wherein the paper-based blank comprises a first portion, a second portion, and a connecting panel, wherein the first portion comprises three main panels and an optional secondary panel, configured to be folded relative to each other and form a plurality of inside surfaces of said corner piece, wherein the second portion comprises three main panels and an optional secondary panel, configured to be folded relative to each other and form a plurality outside surfaces of said corner piece, wherein the first portion and the second portion are foldably connected to each other by the connecting panel, wherein the blank of a cellulose-based low-density material comprises three panels configured to be folded relative to each other and to be positioned between the first portion and the second portion of the paper-based blank such that each of the three panels of the blank of a cellulose-based low-density material is positioned between a respective set of a main panel of the first portion and an associated main panel of the second portion, when the corner piece is formed.

[0012] An advantage with the invention is that it is possible to store and transport the blanks in a flat laid state. By being provided with a paper-based blank and a blank of a cellulose-based low-density material the invention addresses at least that the corner piece is space efficient during transport and storage since it can be stored in a flat laid state. This will in turn enable efficient stacking of the blanks.

[0013] Another advantage with the invention is that it is easy to prepare to use. By being provided with a first portion, a second portion and a connecting panel, being foldably connected, the corner piece addresses at least the design criteria of being easy to prepare for use. By being provided with a blank of a cellulose-based low- density material configured to be folded, the corner piece addresses at least the design criteria of being easy to prepare for use.

[0014] An advantage with the invention is that it provides a strong structure during use. By being provided with a blank of a cellulose-based low-density material, configured to be, positioned between a respective set of main panels a sandwich structure is formed. The paper-based layers are good to distribute loads while the cellulose-based low-density material is good at absorbing shocks, which addresses at least the design criteria of providing a strong structure during use.

[0015] It may be noted that, the inside surfaces of the corner piece formed by the three main panels and the optional secondary panel of the first portion does not necessarily mean that the three main panels are the very innermost surfaces of the corner piece, nor necessarily that two main panels and the optional secondary panel form the very innermost surfaces of the corner piece. It is conceivable that there are provided additional panels folded to one or more of the three main panels or to the optional secondary panel. The term inside surfaces is more related to the fact that they are located closer to an inside surface of the corner piece compared to the position of the cellulose-based low-density panels. It may for instance be noted that in a preferred embodiment one of the main panels is covered by said secondary panel of the first portion, such that the innermost inside surfaces, i.e. the surfaces facing inwardly when the corner piece is formed, are formed on two sides of two main panels and on a third side at least partly by the secondary panel of the first portion.

[0016] It may be noted that the outside surfaces of the corner piece, formed by the three main panels and the optional secondary panel of the second portion does not necessarily mean that the three main panels are the very outermost surfaces of the corner piece, nor necessarily that two main panels and the optional secondary panel form the very outermost surfaces of the corner piece. It is conceivable that there are provided additional panels folded to one or more of the three main panels or to the optional secondary panel. Outside surfaces is more related to the fact that they are located closer to an outside surface of the corner piece compared to the position of the cellulose-based low-density panels. In a preferred embodiment said optional secondary panel is folded inside of one of the main panels of the second portion, such that the outside surfaces of the corner piece are formed by the three main panels of the second portion. It may be noted that the panels of the blank of a cellulose-based low-density material are preferably connected to each other by a hinge of the cellulose-based low-density material but it is also conceivable that the panels of the blank may be separate from each other. In any case, the panels of the blank of a cellulose-based low-density material are preferably interconnected to each other by being attached to the main panels of the first portion of the paper-based blank.

[0017] In a preferred embodiment, the main panels of the first portion are configured to be folded such that a respective first major surface of the respective main panel are folded towards each other and the blank of a cellulose-based low- density material is positioned on the second major surface of the first portion of the paper-based blank. In a preferred embodiment, the size of the blank of a cellulose- based low-density material is generally equal to the size of the first portion allowing the main panels of the first portion to be folded relative to each other with the blank of a cellulose-based low-density material ending up outside of the thus folded first portion. A major surface generally relates to the surface or surfaces with the greatest surface area of a panel, typically a top or bottom surface such as a surface extending orthogonally in relation to the thickness direction of the panel. It may be noted that the paper-based blank may have additional panels such that the surface area becomes larger. Equal in size refers to that dimensions of features of the first portion that have a corresponding feature of the blank of a cellulose-based low- density material are equal to dimensions of said corresponding feature of the blank of a cellulose-based low-density material. In a preferred embodiment the size of the second portion is larger than the respective size of the first portion and of the blank of a cellulose-based low-density material allowing the folded first portion and folded blank of a cellulose-based low-density material to fit inside the folded second portion. The difference in size is preferably such that there is a resulting distance between the folded first portion and the folded second portion corresponding to a material thickness of the blank of a cellulose-based low-density material.

[0018] Preferably, the blank of a cellulose-based low-density material is formed from a cellulose-based air laid substrate or solid cellulose foam substrate. An advantage with the blank of a cellulose-based low-density material being cellulose based is that it is typically more environmentally friendly compared to a polymer based foam, such as e.g., EPS. A further advantage is that the whole kit, and typically also the package in which the corner piece is to be positioned, will be cellulose based since paper-based materials are cellulose based, whereby recycling is facilitated.

[0019] Preferably the blank of a cellulose-based low-density material has a density of 10-120 kg / m3, preferably 10-80kg / m3, and even more preferably 10-60 kg / m3.

[0020] It may be noted that the density refers to the total density of the blank of a cellulose-based low-density material. The local density such as the density at an edge or a surface of the blank of a cellulose-based low-density material may be greater than the density of the bulk of the blank of a cellulose-based low-density material.

[0021] An advantage of having a density of 10-120 kg / m3, preferably 10-80kg / m3, and even more preferably 10-60 kg / m3, is that the corner piece may have a low weight while maintaining a good structural integrity as well as being easy to prepare for use.

[0022] In an embodiment the blank of a cellulose-based low-density material comprises cellulose fibers and a binder, wherein the binder is provided at a concentration within an interval of from 10% up to 30% by weight of said blank.

[0023] It may be noted that the binder may be a polymeric binder. The binder may be polymer fibers having a length weighted average fiber length from 1mm up to 10mm. This provides a strong, yet light-weight material.

[0024] In an embodiment the blank of a cellulose-based low-density material comprises cellulose fibers, at least one, preferably at least two, surfactants and a soluble thickener, wherein the cellulose fibers is provided at a concentration of at least 70 % by weight and the soluble thickener is provided at a concentration within an interval of 4-24% by weight. The at least one surfactant is preferably a fast-acting surfactant, a suitable surfactant for this purpose is an anionic surfactant, preferably a low-molecular weight anionic surfactant. The other one of the preferably at least two surfactants is preferably a co-surfactant. This provides a strong, yet light-weight material. The thickener is preferably water soluble.

[0025] The secondary panel of the first portion may along a first side thereof be separated from a first, neighboring, main panel and may along a second side thereof be foldable to a second, neighboring, main panel allowing the secondary panel to form a double layer with the first main panel of the first portion.

[0026] This allows for the provision of efficient use of material while also providing a blank which will be easy to prepare for use and which may provide a strong corner protection.

[0027] The first portion of the paper-based blank may comprise a locking tab on a first of said main panels, and a locking slot, wherein the locking tab is configured to be received in the locking slot to aid in keeping the first portion in a folded shape, and wherein preferably the locking slot is positioned in fold line between the secondary panel and a second of said main panels

[0028] It may be noted that the second main panel preferably is a panel that is on the opposite side of the secondary panel relative the separation between the secondary panel and the first main panel, wherein the secondary panel and the first main panel are neighboring panels.

[0029] It may be noted that the locking slot preferably is a through-going slot, through-going in the sense as extending through the thickness, but preferably being an internal slot in the sense that there is material forming the fold line outside of the locking slot as seen along the fold line.

[0030] By having a locking tab and a corresponding locking slot on the first portion is that the paper-based blank may be locked in the folded state.

[0031] The secondary panel of the second portion may along a first side thereof be separated from a first main panel and along a second side thereof foldable to a second main panel allowing the secondary panel to form a double layer with the first main panel of the second portion. This allows for the provision of efficient use of material while also providing a blank which will be easy to prepare for use and which may provide a strong corner protection.

[0032] The second portion of the paper-based blank may comprise a locking tab on a first of said main panels and a locking slot, wherein the locking tab is configured to be received in the locking slot to aid in keeping the first portion in a folded shape, and wherein preferably the locking slot is positioned in a fold line between the secondary panel and a second of said main panels.

[0033] It may be noted that the second main panel preferably is a panel that is on the opposite side of the secondary panel relative the separation between the secondary panel and the first main panel, wherein the secondary panel and the first main panel are neighboring panels

[0034] It may be noted that the locking slot preferably is a through-going slot, through-going in the sense as extending through the thickness, but preferably being an internal slot in the sense that there is material forming the fold line outside of the locking slot as seen along the fold line. By having a locking tab and a corresponding locking slot on the second portion is that the paper-based blank may be locked in the folded state.

[0035] Preferably the blank of a cellulose-based low-density material is attached to the paper-based blank to form a single blank.

[0036] It may be noted that the attachment of the blank of a cellulose-based low- density material and paper-based blank may be made by any available means, such as by an adhesive layer formed of a strip or a glue or by heat sealing.

[0037] Having the blank of a cellulose-based low-density material attached to the paper-based blank makes it easier to transport and to prepare the blank for use.

[0038] More preferably the blank of a cellulose-based low-density material is attached to the first portion of the paper-based blank to form a single blank.

[0039] The panels of the blank of a cellulose-based low-density material may be connected to each other forming a single piece and may be foldably connected by a respective hinge between two adjacent panels. The respective hinge is as seen along a material thickness preferably located on an inside surface of said blank.

[0040] It may be noted that the respective hinges may be part of the blank of a cellulose-based low-density material. The blank of a cellulose-based low-density material may be partially cut through a material thickness direction leaving some material to act as a hinge after the cut.

[0041] It may be noted that the inside surface refers to the inside of the folded blank, such as the surfaces facing inwardly i.e. towards the first portion when in use.

[0042] In the preferred embodiment the cellulose-based low-density material is designed to have a denser surface layer, such as having a skin layer, which can act as a hinge, and with the cellulose-based low-density material preferably being oriented such that the denser surface layer faces inwardly towards the product to be protected by the corner piece. It may be noted that the cellulose-base low-density material may have a denser surface on one major surface or on both major surfaces.

[0043] An advantage of the blank of a cellulose-based low-density material being formed from a single piece is that preparation of such a blank is less complex since fewer parts needs to be aligned and put in their intended positions.

[0044] The respective hinge may be an intermittent hinge interrupted by cuts extending into at least one of said two adjacent panels, preferably extending alternatingly into both adjacent panels.

[0045] An advantage of having an intermittent hinge interrupted by cuts extending into one or both of the panels of the cellulose-based low-density material is that the panels may, when folded, occupy some otherwise unoccupied space, thus being able to act as a more efficient shock absorber. The edges of the corner piece will therefor also be able to make use of the shock absorbing properties of the cellulose-based low-density material.

[0046] The cuts may have a respective extension into the respective panel being smaller than or equal to a material thickness of the cellulose-based low-density material. The cuts may be orthogonal in relation to a surface of the material which is cut, such that a cut with an extension equal to the material thickness may extend through the whole material as seen in a thickness direction. The cuts could be made at an angle in relation to the surface of the material which is cut, further the extension could be greater than the material thickness such that the cut extends through the whole material as seen in a thickness direction. Thus, irrespective of the angle and the extension, the cut may be formed fully through the material or be formed such that there is a thin layer of material forming a hinge.

[0047] It may be noted that the blank of a cellulose-based low-density material, when folded such that the panels of the blank of a cellulose-based low-density material are orthogonally positioned in relation to each other, will at least partially fill a respective outer corner void, the void being defined by a respective fold line of the first portion of the paper-based blank, a respective material thickness of the panels of blank of a cellulose -based low-density material and a respective fold line of the second portion of the paper-based blank.

[0048] An advantage of the cuts having an extension being smaller than or equal to a material thickness of the cellulose-based low-density material is that, in the preferred embodiment, the cellulose-based low-density material will properly fit in between the first and section portion of the paper-based blank, when folded, without the need to have excessively large paper-based blanks.

[0049] The above mentioned object of the invention has also been achieved by a corner piece comprising: a paper-based blank, and a blank of a cellulose-based low-density material, wherein the paper-based blank comprises a first portion, a second portion, and a connecting panel, wherein the first portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality of inside surfaces of said corner piece, wherein the second portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality outside surfaces of said corner piece, wherein the first portion and the second portion are foldably connected to each other by the connecting panel, wherein the blank of a cellulose-based low-density material comprises three panels folded relative to each other and to positioned between the first portion and the second portion of the paper-based blank such that each of the three panels of the blank of a cellulose-based low-density material is positioned between a respective set of a main panel of the first portion and an associated main panel of the second portion.

[0050] The advantages associated with the various features have been discussed above with reference to the kit of parts and those are equally applicable to the corner piece. Moreover, the various preferred embodiments and variants of the kit of parts and the features and associated advantages are also equally applicable to the corner piece.

[0051] It may be noted that the use of first, second, third, fourth, fifth, etc. are mainly to be seen as labels facilitating reading and that it does not necessarily mean that there need to be all the intervening numbers of portions present. However, to facilitate reading, we have consistently used the numbering first, second, third, fourth, etc., as labels, and in a sense based on an embodiment including all conceivable portions.

[0052] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Brief description of the drawings

[0053] The invention will by way of example be described in more detail with reference to the appended schematic drawings, which shows a presently preferred embodiment of the invention.

[0054] Figure 1 discloses a blank of a cellulose-based low-density material on a paper-based blank.

[0055] Figure 2 discloses a corner piece.

[0056] Figure 3a discloses a paper-based blank.

[0057] Figure 3b discloses a blank of a cellulose-based low-density material.

[0058] Figure 4 discloses an exploded view of the blank of a cellulose-based low- density material on top of the paper-based blank.

[0059] Figure 5 discloses a folded state of the blank of a cellulose-based low-density material.

[0060] Figures 6a-h disclose step by step a folding operation of folding the blank of Figure 1 into a corner piece as shown in Figure 2.

[0061] Detailed description of preferred embodiments

[0062] With reference to Fig. 1, there is disclosed a kit of parts comprising a paperbased blank 2 and a blank 10 of a cellulose-based low-density material. Solid lines generally refer to cut lines where the material is cut fully through the respective material thickness and dashed lines generally refer to fold lines.

[0063] The paper-based blank 2 comprises a first portion 20, a second portion 30, and a connecting panel 40. The first portion comprises three main panels 21a-c and a secondary panel 22. The three main panels 21a-c are configured to form a plurality of inside surfaces of said corner piece 1. In the preferred embodiment the secondary panel 22 may in fact be one of the innermost inside surface such as facing inwardly when the corner piece is formed, inwardly here refers to the direction towards a corner when the corner piece is in use. In the preferred embodiment the three main panels 21a-c and the secondary panel 22 is of similar size and shape. The secondary panel 22 of the first portion 20 may along a first side thereof be separated from a first, neighboring, main panel 21c such as being cut or by other means separated. The secondary panel 22 may along a second side thereof be foldable to a second, neighboring, main panel 21a. The three main panels 21a-c are preferably defined by crease lines. The three main panels may also be defined by other indications of where a fold could be located or even just be defined by imaginary lines. The secondary panel 22 is preferably defined relative to one main panel 21a by a crease line and separated from another main panel 21c by a cut.

[0064] The secondary panel 22 may be folded such that it forms a double layer with the first main panel 21c of the first portion 20, or the secondary panel 22 may alternatively be folded to form a double layer with the second main panel 21a.

[0065] The first portion 20 of the paper-based blank 2 may comprise a locking tab on a first panel 21c of said main panels 21a-c, and a locking slot 24 in fold line between the secondary panel 22 and a second panel 21a of said main panels 21a-c. The locking tab 23 may have any suitable shape. The locking tab 23 is preferably formed of a portion being cut-out from the secondary panel 22. The locking tab 23 may have an extension in a direction towards the locking slot 24 where the extension is big enough for the locking tab 23 to be able to be received into the locking slot 24, holding the main panel in place. The locking slot 24 will in turn be wide enough to be able to receive the locking tab 23. The locking slot is preferably located in a fold line between the secondary panel 22 and second main panel 21a. The locking slot 24 could alternatively be located on a main panel or between any fold line.

[0066] The second portion 30 comprises three main panels 31a-c and a secondary panel 32. The three main panels 31a-c are configured to form a plurality of outside surfaces of said corner piece 1. In the preferred embodiment the secondary panel 22 may in fact be one of the outermost outside surface such as facing outwardly when the corner piece is formed, outwardly here refers to the direction away from a corner when the corner piece is in use. In the preferred embodiment the three main panels 31a-c and the secondary panel 32 is of similar size and shape. The three main panels 31a-c are preferably defined by crease lines. The three main panels 31a-c may also be defined by other indications of where a fold could be located or even just be defined by imaginary lines. The secondary panel 32 is preferably defined relative one main panel 31a by a crease line and separated from another main panel by a cut 31c.

[0067] The second portion 30 of the paper-based blank 2 may comprise a locking tab on a first panel 31c of said main panels 31a-c, and a locking slot 34 in a fold line between the secondary panel 32 and a second panel 31a of said main panels 31a-c. The locking tab 33 may have any suitable shape. The locking tab 33 is preferably formed of a portion being cut-out from the secondary panel 32. The locking tab 33 may further have an extension in a direction towards the locking slot 34 where the extension is big enough for the locking tab 33 to be able to be received into the locking slot 34, holding the main panel in place. The locking slot 34 will in turn be wide enough to be able to receive the locking tab 33. The locking slot is preferably located in a fold line between the secondary panel 32 and second main panel 31a. The locking slot 34 could alternatively be located on a main panel or between any fold line.

[0068] In the preferred embodiment the second portion 30 of the paper-based blank 1 has a major surface having a size that is greater than a size of a major surface of the first portion 20 of the paper-based blank. Equally a respective main panel 31a-c of the second portion has a size greater than a size of a respective main panel 21a-c of the first portion.

[0069] The paper-based material is preferably a corrugated board. The flute types of the corrugated board may vary from N to C and could also be double walled such as E / B or other suitable combinations as well. This is applicable for any paper-based layer discussed herein.

[0070] The width w of the connecting panel 40 is equal to or greater than the thickness t of the blank 10 of a cellulose-based low-density material. In the preferred embodiment the connecting panel is foldably connect to both the first portion 20 and second portion 30 of the paper-based blank. The connecting panel may enable the first portion and the second portion of the paper-based blank to be folded into a respective corner piece with a spacing in between. The spacing between the portions is equal to the thickness of the connecting panel, which assist the blank 10 of a cellulose-based low-density material to fit in between the first and second portion, when folded.

[0071] The blank 10 of a cellulose-based low-density material may be referred to as a cellulose-based low-density substrate. The term cellulose-based low-density substrate refers to a low-density substrate comprising cellulose as its main part or constituent. Various such cellulose materials could be comprised in the cellulose- based low-density substrate including, but not limited to, cellulose fibers, particles, and / or cellulose fibrils. The low-density cellulose-based substrate is further characterized by being porous and having the structure of an open cell foam. The density of the cellulose-based low-density substrate is thus low compared to the density of a non-porous cellulose-based substrate with similar dimensions.

[0072] In some embodiments, the density of the cellulose-based low-density substrate is in the range of from 10 to 120 kg / m3, such as from 10 to 80 kg / m3, or from 10 to 60 kg / m3.

[0073] In a preferred embodiment, the cellulose-based low-density substrate comprises cellulose fibers. The cellulose fibers may comprise lignin and / or hemicellulose, or may be free from lignin and hemicellulose. The cellulose fibers can originate from wood, such as hardwood or softwood. The cellulose fibers may also originate from other raw materials such as flax, jute, hemp, cotton, kenaf, bagasse, bamboo, straw or rice husk. Mixtures of fibers originating from different raw materials may also be used.

[0074] Preferably, the cellulose fibers originate from wood, and more preferably the cellulose fibers are pulp fibers produced by pulping processes such as mechanical pulping, chemical pulping and / or chemi-mechanical pulping processes. The pulp fibers may be selected from the group consisting of Kraft pulp, sulfite pulp, dissolving pulp, thermomechanical pulp (TMP), high temperature thermomechanical pulp (HTMP), chemi-thermomechanical pulp (CTMP), mechanical fiber intended for medium density fiberboard (MDF-fiber), high temperature chemi-thermomechanical pulp (HTCTMP) and a combination thereof. The pulp fibers may be bleached or unbleached.

[0075] Length of fibers, such as cellulose fibers, as referred to herein is length weighted average fiber length. Length weighted average fiber length is calculated as the sum of individual fiber lengths squared divided by the sum of the individual fiber lengths as described in e.g., ISO 16065-1 or ISO 16065-2.

[0076] In an embodiment, the cellulose fibers have a length weighted average fiber length of up to 10 mm, or of up to 8 mm, or up to 6 mm, or up to 5 mm. In a particular embodiment, the cellulose fibers have a length weighted average fiber length selected within an interval of from 0.5 mm up to 10 mm, or selected within an interval of from 0.5 mm up to 8 mm, or selected within an interval of from 0.5 mm up to 6 mm, or selected within an interval of from 0.5 mm up to 5 mm. It is also possible to include a fraction of fibers having a weighted average fiber length of 10 mm or more. The aspect ratio, i.e. the ratio of the fiber length to the fiber width, of the cellulose fibers can be at least 5, at least 10, at least 25, at least 50, at least 75, or at least 100.

[0077] In one embodiment the blank 10 of a cellulose-based low-density material, may be formed of an air-laid material. The air-laid material comprises cellulose fibers and a binder. The air-laid material may also comprise one or more additives. The air-laid material is formed by a process known as air-laying, in which cellulose fibers and polymer binders are mixed with air to form a porous fiber mixture deposited onto a support and consolidated or bonded by heating. This air-laid material, sometimes also referred to as dry-laid material, is characterized by being porous, having the character of an open cell foam and being produced in a so-called dry forming method, i.e., generally without addition of water. An air-laying process is e.g., described in U.S. patent no. 3,575,749.

[0078] The cellulose fibers are being provided at a concentration of at least 70 % by weight of the air-laid material. Preferably, the air-laid material comprises the cellulose fibers in a concentration of at least 72.5 %, more preferably at least 75 %, such as at least 77.5 %, at least 80 %, at least 82.5 %, at least 85 % by weight of the air-laid material. In some applications, even higher concentrations of the cellulose fibers may be used, such as at least 87.5 %, or at least 90 %, at least 92.5 %, at least 95 % or at least 96 % by weight of the air-laid material.

[0079] The binder may comprise a polymer binder. The polymer binder being e.g., a thermoplastic polymer binder, may be provided at a concentration selected within an interval of from 2.5 up to 30 % by weight of the air-laid material.

[0080] In one embodiment of the air-laid material, the air-laid material comprises the thermoplastic polymer binder at a concentration selected within an interval of from 10 up to 30 %, such as from 15 up to 30 % by weight of the air-laid material 100. In a particular embodiment, the air-laid material comprises more than 15 % but no more than 30 % by weight of the thermoplastic polymer binder. For instance, the air-laid material may comprise the thermoplastic polymer binder at a concentration selected within an interval of from 15 or 17.5 up to 30 % by weight of the air-laid material. In a particular embodiment, the air-laid material comprises the thermoplastic polymer binder at a concentration selected within an interval of from 15 or 17.5 up to 25 %, such as from 20 up to 25 % by weight of the air-laid material.

[0081] In one embodiment of the air-laid material, the air-laid material comprises the thermoplastic polymer binder at a concentration selected within an interval of from 2.5 up to 15 % by weight of the air-laid material, preferably within an interval of from 4 up to 15 % by weight of the air-laid material, or within an interval of from 7.5 up to 15 % by weight of the air-laid material, and more preferably within an interval of from 10 up to 15 % by weight of the air-laid material. These embodiments are, in particular, suitable for usage with thermoplastic polymer binders that are water soluble, e.g., for usage with thermoplastic polymer fibers made from a material or materials selected from the group consisting of polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly(2-ethyl-2-oxazoline) (PEOX), polyvinyl ether (PVE), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polymethacrylic acid (PMAA) and copolymers and / or mixtures thereof.

[0082] The thermoplastic polymer binder is included in the air-laid material as binder that binds the air-laid material together and preserves its form and structure during use, handling and storage. The thermoplastic polymer binder may also assist in building up a foam-like structure of the air-laid material. The thermoplastic polymer binder is intermingled with the cellulose fibers during the air-laying process forming a fiber mixture. The thermoplastic polymer binder may be added in the form of a powder, but are more often in the form of fibers that are intermingled with the natural fibers in the air-laying process. Alternatively, or in addition, the thermoplastic polymer binder may be added as solution, emulsion or dispersion into and onto the air-laid material during the air-laying process. This latter technique is most suitable for thin air-laid materials.

[0083] The thermoplastic polymer binder may be selected from the group consisting of a thermoplastic polymer powder, thermoplastic polymer fibers and a combination thereof.

[0084] The thermoplastic polymer binder has a softening point not exceeding a degradation temperature of the cellulose fibers.

[0085] In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises thermoplastic polymer fibers cut at a fixed length, which are typically referred to as staple fibers. It is generally preferred for the mixing in the airlaying process and, thereby, for the properties of the formed air-laid material if the length of the thermoplastic polymer fibers is of the same order of magnitude as the length of the cellulose fibers.

[0086] In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises thermoplastic polymer fibers having a length-weighted average fiber length that is selected within an interval of from 75 % up to 300 %, preferably from 80 % up to 250 %, and more preferably from 90 % up to 220 %, such as from 95 % up to 200 % of a length weighted average fiber length of the cellulose fibers. In a particular embodiment, the thermoplastic polymer fibers have a length weighted average fiber length within an interval of from 1 up to 10 mm, preferably within an interval of from 2 up to 8 mm and more preferably within an interval of from 2 up to 6 mm.

[0087] In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises mono-component and / or bi-component thermoplastic polymer fibers. Bi-component thermoplastic polymer fibers, also known as bico fibers, comprise a core and sheath structure, where the core is made from a first polymer, copolymer and / or polymer mixture and the sheath is made from a second, different polymer, copolymer and / or polymer mixture.

[0088] In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises, such as consists of, mono-component thermoplastic polymer fibers made of a material selected from the group consisting of polyethylene (PE), ethylene acrylic acid copolymer (EAA), ethylene-vinyl acetate (EVA), polypropylene (PP), polystyrene (PS), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyethylene terephthalate (PET), polycaprolactone (PCL) and copolymers and / or mixtures thereof. In another embodiment, the thermoplastic polymer binder is or comprises, such as consists of, bi-component thermoplastic polymer fibers having a core and / or sheath made of a material or materials selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL and copolymers and / or mixtures thereof. In a further embodiment, the thermoplastic polymer binder is or comprises, such as consists of, a combination or mixture of mono-component thermoplastic polymer fibers made of a material selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL and copolymers and / or mixtures thereof and bi-component thermoplastic polymer fibers having a core and / or sheath made of a material or materials selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL and copolymers and / or mixtures thereof.

[0089] The thermoplastic polymer binder could be made of a single type of thermoplastic polymer fibers, i.e., made of a same material in the case of monocomponent thermoplastic polymer fibers or made of the same material or materials in the case of bi-component thermoplastic polymer fibers. However, it is also possible to use a thermoplastic polymer binder made of multiple different monocomponent thermoplastic polymer fibers made of different materials and / or multiple different bi-component thermoplastic polymer fibers made of different materials. In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises a thermoplastic polymer powder made of a material selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL and copolymers and / or mixtures thereof.

[0090] Particular examples of material for the thermoplastic polymer binder that could be used according to the present embodiments include PBAT, PBS, PLA, PCL, and copolymers and / or mixtures thereof. In such a case, the thermoplastic polymer binder made of these materials is compostable under industrial conditions.

[0091] Other examples of material for the thermoplastic polymer binder, which are water soluble, are mono-component and / or bi-component thermoplastic polymer fibers made of a material selected from the group consisting of polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly(2-ethyl-2-oxazoline) (PEOX), polyvinyl ether (PVE), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polymethacrylic acid (PMAA) and copolymers and / or mixtures thereof.

[0092] In one embodiment of the air-laid material, the thermoplastic polymer binder is or comprises, such as consists of, mono-component thermoplastic polymer fibers made of a material selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PMAA and copolymers and / or mixtures thereof. In another embodiment, the thermoplastic polymer binder is or comprises, such as consists of, bi-component thermoplastic polymer fibers having a sheath or a sheath and core made of a material or materials selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PM MA and copolymers and / or mixtures thereof. In a particular embodiment, at least the sheath of the bi-component thermoplastic polymer fibers is made of a material selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PMAA and copolymers and / or mixtures thereof. In such a particular embodiment, also the material of the core of the bi-component thermoplastic polymer fibers could be selected from this group. Hence, in one particular embodiment, the bi-component thermoplastic polymer fibers comprise a core component made of a material selected from the group consisting of polyethylene PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL and copolymers and / or mixtures thereof and a sheath component made of a material selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PMAA and copolymers and / or mixtures thereof. In a further embodiment, the thermoplastic polymer binder is or comprises, such as consists of, a combination of mono-component thermoplastic polymer fibers made of a material selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PMAA and copolymers and / or mixtures thereof and bicomponent thermoplastic polymer fibers having a core and / or sheath made of a material or materials selected from the group consisting of PVA, PEG, PEOX, PVE, PVP, PAA, PMAA and copolymers and / or mixtures thereof.

[0093] In another embodiment I blank 10 of a cellulose-based low-density material may be formed of a foam, preferably a cellulose foam. The term "foam", as used herein, refers to a substance made by trapping air or gas bubbles inside a solid or liquid. Typically, the volume of gas is much larger than that of the liquid or solid, with thin films separating gas pockets. Three requirements must be met in order for foam to form. Mechanical work is needed to increase the surface area. This can occur by agitation, dispersing a large volume of gas into a liquid, or injecting a gas into a liquid. The second requirement is that a foam forming agent, typically an amphiphilic substance, a surfactant or surface active component, must be present to decrease surface tension. Finally, the foam must form more quickly than it breaks down.

[0094] The term "cellulose foam", as used herein, refers to a foam comprising cellulose, and other components such as thickeners, surfactants and additives. The main component of the cellulose foam is cellulose, such that cellulose constitutes at least 70 wt% of the dry content of the cellulose foam. Cellulose is in the form of fibers, and the foam can thus also be defined to be a fibrous foam or a cellulose fiber foam. The cellulose foam may be wet or solid.

[0095] The term "wet foam", or "wet cellulose foam", as used herein, refers to a wet foam comprising cellulose, and other components such as thickeners, surfactants and additives. Gas bubbles are present within the wet foam. The wet foam is freestanding and behaves as a viscoelastic solid. This means that the wet foam has both viscous and elastic properties. The wet foam will behave as a solid, and thus be freestanding, unless a large enough force is applied so that it starts to flow and instead behave as a viscous material. Depending on the magnitude and timescale of any applied shear stress, the wet foam can show a predominantly viscous or elastic behavior.

[0096] The term "solid cellulose foam", or "dry cellulose foam", as used herein, refers to a dry porous cellulose material that has been formed from a wet cellulose foam, i.e. a foam formed material. During the drying process, a closed wet cellulose foam is transformed into an open solid cellulose foam. The network of cellulose fibers is prevented from collapsing during drying. The solid cellulose foam will as a result have a shape that to a large extent corresponds to that of the wet cellulose foam. The dry content of the solid cellulose foam is at least 95 wt% as calculated based on the total weight of the solid cellulose foam. The shape and density of the solid cellulose foam is retained also in a non-confined state. The solid cellulose foam has an open cell structure, allowing air to occupy the pores within the foam. The solid cellulose foam can also be described as a porous material or a low-density material. The cellulose foam is a solid cellulose foam, i.e. it is dry and may have a solid content in the range of from 95 to 100 wt%, preferably from 98 to 100 wt%, as calculated on the total weight of the solid cellulose foam.

[0097] The cellulose foam preferably comprises cellulose fibers in a range of from 71 to 95 wt%, such as from 75 to 95 wt%, based on the total dry weight of the cellulose foam, a water-soluble thickener in a range of from 4 to 24 wt%, such as from 5 to 20 wt%, based on the total dry weight of the cellulose foam, and at least two surfactants.

[0098] Preferably, the cellulose fibers are selected from wood pulp, such as softwood Kraft bleached pulp, hardwood pulp, chemical-thermomechanical pulp, and from dissolving pulp, or a combination of one or more of these. More preferably the cellulose pulp fibers are from softwood pulp, chemical-thermomechanical pulp, or dissolving pulp. Most preferably the cellulose pulp fibers are from softwood pulp, such as softwood Kraft bleached pulp. The cellulose fibers may be modified to provide different properties to the final cellulose foam. For example, phosphorylated fibers or periodate oxidized fibers could also be used when producing a cellulose foam according to the present invention.

[0099] The water-soluble thickener may have a molecular weight of from 80000- 250000 g / mol, or from 83 000-197 000 g / mol. Exemplary water-soluble thickeners are selected from carboxy methyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose (HEC), ethyl hydroxyethyl cellulose (EHEC), methyl hydroxypropyl cellulose (MHPC), starch, xanthan, guar gum, and xyloglucan, or mixtures thereof. The fact that the thickener is water-soluble facilitates recycling of the cellulose foam.

[0100] The water-soluble thickener may improve the fiber-fiber bonding strength, primarily through hydrogen bonding, in the cellulose foam, Therefore, the amount of water-soluble thickener will influence the mechanical performance of the cellulose foam, and especially the bulk of the material. A higher content of water- soluble thickener provides for a stiffer material. Thus, the water-soluble thickener enables tailoring of the mechanical properties of the cellulose foam.

[0101] The cellulose foam may also comprise a mixture of at least two surfactants. One of the at least two surfactants is preferably a fast-acting surfactant, a suitable surfactant for this purpose is an anionic surfactant, preferably a low-molecular weight anionic surfactant. The anionic surfactant may have an apparent pKa of from 3.2 to 3.8, preferably from 3.4 to 3.6, or an apparent pKa of 3.5 in a solution having a pH of from 7 to 9, preferably a pH of 8. The low-molecular weight anionic surfactant may be selected from sodium dodecyl sulphate (SDS); potassium dodecyl sulphate, sodium laureth sulphate (SLES); sodium dodecylbenzenesulphonate; sodium cocoyl sarcosinate; sodium lauroyl sarcosinate. The low-molecular weight anionic surfactant is preferably selected from sodium dodecyl sulphate (SDS); sodium p-n- dodecylbenzenesulphonate; sodium cocoyl sarcosinate; and sodium lauroyl sarcosinate. More preferably the low-molecular weight anionic surfactant is sodium cocoyl sarcosinate. The anionic surfactant may be biodegradable. The other one of the at least two surfactants is preferably a co-surfactant.

[0102] The co-surfactant may be selected from the group comprising surfactants having an apparent pKa of at least 8, or at least 9, in a surfactant solution having pH of from 7 to 9, preferably having a pH of 8; and amphoteric betaines. The co-surfactant may have maximum apparent pKa of 10. The co-surfactant preferably has a long carbon chain, more preferably a carbon chain with 14 carbon atoms (C14). The cosurfactant may be selected from high pKa fatty acids, such as from plant derived feedstock, e.g. tetradecanoic acid (myristic acid), sodium oleate, lauric acid, palmitic acid, and stearic acid; glucose based co-surfactants with an aliphatic carbon tail, such as alkyl glycosides, alkylpolyglucosides, alkyl thio-glycosides, and alkyl maltosides; amphoteric betaines, such as cocamidopropyl betaine (CAPB), and sodium cocoiminodipropionate (CADP); polyethylene glycol sorbitan monolaurate, i.e. tween® (e.g. tween® 20, tween® 80 and tween® 85); and polyoxyethylene lauryl ethers, such as polyethylene glycol dodecyl ether, pentaethylene glycol monododecyl ether and octaethylene glycol monododecyl ether.

[0103] Thus, the at least two surfactants used in the cellulose foam preferably comprise a mixture of an anionic surfactant and a co-surfactant. The molar ratio between anionic surfactant to co-surfactant may be from 0.2:l-3:l, preferably from 0.5:1 to 2:1. The total amount of the at least two surfactants together in the cellulose foam may be 0.6-5 wt%, or 0.8-2.0 wt%, as calculated on the total weight of the cellulose foam.

[0104] The cellulose foam can be re-dispersed in water and as a result be recyclable in regular paper recycling streams.

[0105] The cellulose foam may be prepared using a method comprising the following steps: disintegrating cellulose fibers in water to obtain a slurry of cellulose fibers; adding a water-soluble thickener to the slurry to obtain a mixture of thickener and cellulose fibers in water; adding at least two surfactants to the mixture to obtain a fiber suspension; and aerating the fiber suspension to obtain a wet foam, wherein the wet foam comprises 10-38 wt% cellulose fibers, 0.5-10 wt% of the water-soluble thickener, and 0.1-2 wt% surfactants, as calculated on the total weight of the wet foam, and wherein the foam has a density of from 140-500 kg / m3and a yield stress of from 40 to 400 Pa; drying the wet foam to obtain a solid cellulose foam.

[0106] Addition of a water-soluble thickener increase the viscosity of the slurry and enables incorporation of enough air to generate a densely packed foam during aeration. Since the cellulose fibers are mixed in high concentrations a drainage step is not needed, which enables the use of a water-soluble bio-based thickener in high concentrations.

[0107] Addition of a fast-acting surfactant will contribute to the formation of a cellulose foam with a high density and a high viscosity as it will quickly settle at the air-water interphase during aeration. This enables a free-standing wet cellulose foam. Addition of a co-surfactant along with the fast-acting surfactant will further improve the properties of the cellulose foam since it will facilitate the action of the fast-acting surfactant. A co-surfactant having a suitable pKa and a long carbon chain further contributes to a stable fiber suspension and a stable wet cellulose foam.

[0108] Upon aeration the composition comprising cellulose fibers, thickener and at least two surfactants will form a highly stable wet fiber foam. The aeration may be performed by mechanical agitation, and a substantial amount of air is incorporated into the material. The formation of a foam will be promoted by the surfactants. By adjusting the stability of the wet foam with the use of thickeners and surfactant combinations, a free-standing cellulose foam can be made without the use of a cross-linker or fibrillated cellulose. A good stability of the foam prevents ripening, i.e. change in bubble size, and drainage. The obtained wet foam is free-standing and does not require a mould or a forming fabric to retain its shape upon drying. The wet foam can thus be formed into a free-standing foam that is stable enough to be dried in the absence of a supporting mould without collapsing. As a result, objects can be formed and dried without the use of a mould.

[0109] The bubble size in the wet foam is typically below 100 pm. This provides for a homogenous wet foam with good stability that does not flocculate during processing. During processing, and also during the subsequent drying step, the average bubble size is maintained to a large extent and the cellulose fibers remain well dispersed. The resulting solid cellulose foam obtained by drying the wet foam will be homogenous in structure, strong, have good mechanical properties, a smooth surface and no defects. A smooth surface may be beneficial when a coating is to be applied on the foam.

[0110] In comparison, a wet cellulose foam with low stability has a larger average bubble size (i.e. typically above 100 pm) and the bubbles will coalesce faster during processing and drying such that larger bubbles are formed. In addition, the cellulose fibers will form clusters during processing and drying. This results in the wet foam collapsing during drying. The resulting solid cellulose foam will not have a homogenous structure and will also contain defects in the form of cavities resulting from the coalesced bubbles in the wet foam. Such a solid cellulose foam is, due to the defects, weak and has a rough surface.

[0111] Because of the high solid content, the wet foam does not need to be dewatered before it is dried. The foam may be dried by evaporation at room temperature or at an elevated temperature, such as a temperature of from 40 -140 °C. The dry cellulose foam may have a density of from 10 to 80 kg / m3, or from 10 to 60 kg / m3, or from 20 to 50 kg / m3.

[0112] In preferred embodiments the cellulose foam comprises cellulose fibers in a range of from 71 to 95 wt%, such as from 75 to 95 wt%, based on the total dry weight of the cellulose foam, a water-soluble thickener in a range of from 4 to 24 wt%, such as from 5 to 20 wt%, based on the total dry weight of the cellulose foam, and at least two surfactants. A wet cellulose foam having such a composition is homogenous in structure and has a good stability as discussed above. Such a wet cellulose foam can also be dried without prior dewatering.

[0113] The solid cellulose foam may have any shape, such as a block, a cube, a cylinder or any irregular shape.

[0114] In one embodiment of the solid cellulose foam, the solid cellulose foam is provided in the form of a plank having a thickness in the range of from 1 to 20 cm, preferably from 1 to 10 cm, more preferably from 1 to 6 cm. The length and width dimensions of the plank are typically in the range of from 100 to 300 cm. The planks may be cut into smaller pieces and may be split into thinner panels.

[0115] The solid cellulose foam may on at least one outer surface have a densified layer. In embodiments where the cellulose foam is provided in the form of a plank, the cellulose foam has densified layers on at least the top surface and bottom surface, and optionally on the side surfaces.

[0116] The densified layer comprises cellulose fibers that are packed more tightly and partly oriented differently compared to the bulk leading to a higher number of fiber-fiber bonds. The densified layer is formed on the outer surface of the wet foam during drying of the wet foam and remain on the outer surface of the solid cellulose foam when dried. The densified layers have improved mechanical stability and strength as compared to the core of the solid cellulose foam. The core of the solid cellulose foam comprises a homogenous open-cell fiber network. The core is highly porous, and even though the densified layer has a denser structure than the core, it is still porous.

[0117] The densified layer thus provides the solid cellulose foam with increased stability and mechanical strength. In embodiments where the solid cellulose foam is provided in the form of a plank, it is therefore preferable that during cutting of the foam planks, cutting is carried out such that either the thickness of the planks remains the same also after cutting, thus ensuring that the densified layers are still present on the top surface and bottom surface, or such that splitting is performed such that a densified layer is present on one of the major surfaces.

[0118] In the preferred embodiment the blank 10 of a cellulose-based low-density material has a smaller size than the second portion 30 of the paper-based blank 2. Preferably the blank 10 of a cellulose-based low-density material has a size corresponding to the size of the first portion 20 of the paper-based blank 2.

[0119] The blank 10 of a cellulose-based low-density material comprises three panels lla-c configured to be folded. The three panels lla-c of the blank 10 of a cellulose-based low-density material are preferably connected to each other and even more preferably foldably connected to each other. In the preferred embodiment the three panels lla-c are foldably connected by a respective hinge between adjacent panels. The hinge is as seen along a material thickness located on an inside surface. The inside surface is the surface that faces towards the first portion 20 of the paper-based blank, when the corner piece is folded. In an embodiment the hinge may be formed of the blank 10 of a cellulose-based low- density material, such as being some material left after a cut in a thickness direction of the blank 10 of a cellulose-based low-density material. In an embodiment the foam is designed to have a denser outer layer such as having a skin layer which can act as a strong hinge. Further, the hinge may be an intermittent hinge interrupted by cuts extending into both of the panels of the blank 10 of a cellulose-based low- density material, preferably alternatingly into both panels, such as forming a blocklike jigsaw pattern. When folded the jigsaw pattern may be designed as to occupy space that would otherwise be empty space. The jigsaw pattern may strengthen the corner edges of the corner piece by introducing a shock absorber in the form of cellulose-based low-density material. In the preferred embodiment the cuts have an extension into the respective panel being smaller than or equal to a material thickness of the cellulose-based low-density material . The cuts will then produce a jigsaw pattern, which when folded, can strengthen the corner edges of the corner piece without interfering with the folding of the first or second portion of the paperbased blank. The shape of the jigsaw is preferably oblong or square. These shapes will in the preferred embodiment have the possibility to minimize the void space around the edges of the corner piece.

[0120] The blank 10 of a cellulose-based low-density material may be positioned between the first portion 20 and the second portion 30 of the paper-based 2 blank such that each of the three panels of the blank 10 of a cellulose-based low-density material is positioned between a respective set of a main panel 21a-c of the first portion and an associated main panel 31a-c of the second portion, when the corner piece is formed by folding. Figs 6a-h shows steps during folding of the paper-based. The secondary panel 33 of the second portion 30 is as shown in Fig. 6b folded upwardly, inwardly and this folding is continued by folding the next main panel 31a as shown in Fig. 6c such that a tetraedic shape is obtained. This tetraedic shape is then folded downwardly onto the first main panel 31c as shown in Fig. 6d and the locking flap 33 is inserted into the locking slot 34 thus forming a self-supporting outer tetraedic shape as shown in Fig. 6e. Next the secondary panel 23 of the first portion 20 is folded as shown in Fig. 6f and this folding is continued by folding the next main panels 21c and 21b as shown in Fig. 6g such that a tetraedic shape is obtained and the locking tab 23 is inserted into the locking slot 24 such that a self-supporting inner tetraedic shape is obtained. Finally the inner tetradic shape is folded into the outer tetraedic shape as shown in Fig. 6h. It may be noted that in Figures 6a-h, the cellulose-based low- density material has been omitted. The cellulose-based low-density material may be a separate blank being folded to a corresponding tetraedic shape and inserted as a step between Figures 6g and 6h. Alternatively, the blank 10 of a cellulose-based low- density material is an integral part of the first portion 20 and is folded into the tetraedic shape simultaneously as the first portion 20 is folded.

[0121] It is contemplated that there are numerous modifications of the embodiments described herein, which are still within the scope of the invention as defined by the appended claims.

[0122] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS1. Kit of parts configured to form a corner piece (1), the kit of parts comprising: a paper-based blank (2), and a blank (10) of a cellulose-based low-density material, wherein the paper-based blank (2) comprises a first portion (20), a second portion (30), and a connecting panel (40), wherein the first portion comprises three main panels (21a-c) and an optional secondary panel (22) configured to be folded relative to each other and form a plurality of inside surfaces of said corner piece (1), wherein the second portion (30) comprises three main panels (31a-c) and an optional secondary panel (32) configured to be folded relative to each other and form a plurality of outside surfaces of said corner piece, wherein the first portion (20) and the second portion (30) are foldably connected to each other by the connecting panel (40), wherein the blank (10) of a cellulose-based low-density material comprises three panels (lla-c) configured to be folded relative to each other and to be positioned between the first portion (20) and the second portion (30) of the paperbased (2) blank such that each of the three panels (lla-c) of the blank (10) of a cellulose-based low-density material is positioned between a respective set of a main panel (21a-c) of the first portion and an associated main panel (31a-c) of the second portion, when the corner piece (1) is formed.

2. The kit according to claim 1, wherein the blank (10) of a cellulose-based low-density material is formed from a cellulose-based air laid substrate or solid cellulose foam substrate.

3. The kit according to claim 1 or 2, wherein the blank (10) of a cellulose- based low-density material has a density of 10-120 kg / m3, preferably 10-80 kg / m3, and more preferably 10-60 kg / m3.

4. The kit according to claim 1-3, wherein the blank (10) of a cellulose-based low-density material is an air-laid material, and comprises cellulose fibers and a binder, wherein the binder is provided at a concentration within an interval of from 10% up to 30% by weight of the said blank5. The kit according to claim 1-3, wherein the blank (10) of a cellulose-based low-density material comprises cellulose fibers, at least one, preferably at least two, surfactants and a soluble thickener, wherein the cellulose fibers is provided at a concentration of at least 70 % by weight and the soluble thickener is provided at a concentration within an interval of 4-24% by weight.

6. The kit according to claim 1-5, wherein the secondary panel (22) of the first portion (20) is along a first side thereof separated from a first main panel (21c) and along a second side thereof foldable to a second main panel (21a) allowing the secondary panel (22) to form a double layer with the first main panel (21c) of the first portion (20).

7. The kit according to claim 1-6, wherein the first portion (20) of the paperbased blank (2) comprises a locking tab (23) on a first of said main panels (21c) and a locking slot (24), wherein the locking tab (23) is configured to be received in the locking slot (24) to aid in keeping the first portion(20) in a folded shape, and wherein preferably the locking slot (24) is positioned in fold line between the secondary panel (22) and a second (21a) of said main panels (21a).

8. The kit according to claim 1-7, wherein the secondary panel (32) of the second portion (30) is along a first side thereof separated from a first main panel(31c) and along a second side thereof foldable to a second main panel (31a) allowing the secondary panel (32) to form a double layer with the first main panel (31c) of the second portion (30).

9. The kit according to claim 1-8, wherein the second portion (30) of the paper-based blank (2) comprises a locking tab (33) on a first (31c) of said main panels (31a-c) and a locking slot (34), wherein the locking tab (33) is configured to be received in the locking slot (34) to aid in keeping the first portion in a folded shape, and wherein preferably the locking slot is positioned in a fold line between the secondary panel (32) and a second (31a) of said main panels (31a)10. The kit according to claim 1-9, wherein the blank (10) of a cellulose-based low-density material is attached to the paper-based blank (2) to form a single blank.

11. The kit according to claim 10, wherein the blank (10) of a cellulose-based low-density material is attached to the first portion (20) of the paper-based blank (2) to form a single blank.

12. The kit according to claim 1-11, wherein the panels (lla-c) of the blank (10) of a cellulose-based low-density material are connected to each other forming a single piece and are foldably connected by a respective hinge between two adjacent panels, wherein the respective hinge is as seen along a material thickness preferably located on an inside surface of said blank.

13. The kit according to claim 12, wherein the respective hinge is an intermittent hinge interrupted by cuts extending into at least one of said two adjacent panels, preferably alternatingly into both adjacent panels.

14. The kit according to claim 13, wherein the cuts have a respective extension into the respective panel being smaller than or equal to a material thickness of the foam.

15. Corner piece comprising: a paper-based blank, and a blank of a cellulose-based low-density material, wherein the paper-based blank comprises a first portion, a second portion, and a connecting panel, wherein the first portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality of inside surfaces of said corner piece, wherein the second portion comprises three main panels and an optional secondary panel folded relative to each other and forming a plurality of outside surfaces of said corner piece, wherein the first portion and the second portion are foldably connected to each other by the connecting panel, wherein the blank of a cellulose-based low-density material comprises three panels folded relative to each other and positioned between the first portion and the second portion of the paper-based blank such that each of the three panels of the blank of a cellulose-based low-density material is positioned between a respective set of a main panel of the first portion and an associated main panel of the second portion.