Press formed packaging

Abstract

According to an example aspect of the present invention, there is provided a container comprising a continuous element forming a body of the container, the element forming a three-dimensional shape of the container wherein a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container, the element having a repeating, pressed folding pattern, wherein an extent of deployment of the folding pattern is greatest in parts of the element where a distance of the element's material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part.

Description

PRESS FORMED PACKAGINGFIELD

[0001] The present disclosure relates to press-formed containers, such as packaging items, such as, for example, those containers and packaging items of paperboard.BACKGROUND

[0002] Food and other products have been stored in a diverse range of containers, such as glass or ceramic jars, airtight metal cans and different kinds of plastic packaging.

[0003] Single-use containers are frequently made of plastic, which offers attractive qualities such as water and gas-tight closure, which delays spoilage and prevents staining from leaking liquids. While plastics may be prepared from various feed materials, including recycled raw material, plastics are frequently prepared from mineral oil or intermediate materials obtained using mineral oil.SUMMARY

[0004] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims.

[0005] According to a first aspect of the present disclosure, there is provided a container comprising a continuous element forming a body of the container, the element forming a three-dimensional shape of the container wherein a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container, the element having a repeating, pressed folding pattern, wherein an extent of deployment of the folding pattern is greatest in parts of theelement where a distance of the element’s material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part.

[0006] According to a second aspect of the present disclosure, there is provided a method of manufacturing a container, comprising imparting a repeating folding pattern to a continuous planar element, forming the container by employing a compressive process on the continuous planar element after the imparting of the repeating folding pattern, whereby a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container, wherein an extent of deployment of the folding pattern caused by the compressive process is greatest in parts of the element where a distance of the element’s material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIGURE 1 A illustrates phases of container preparation;

[0008] FIGURE IB illustrates phases of container preparation in accordance with at least some embodiments of the present invention;

[0009] FIGURE 2A illustrates an example container in accordance with at least some embodiments of the present invention;

[0010] FIGURE 2B illustrates a rate of change in accordance with at least some embodiments of the present invention;

[0011] FIGURE 3 is a flow graph of a method in accordance with at least some embodiments of the present invention, and

[0012] FIGs. 4A - 4G illustrate an example pressed cup.EMBODIMENTS

[0013] Containers, such as food containers, are obtained as herein described using a planar element, for example paperboard, which is first impressed with a folding pattern and then press formed to obtain a three-dimensional container, for example a single-use plate,cosmetics container, egg cell, food or confectionery package or a sales or shipping package for electronics or cosmetics, for example. In particular, the container may be used to pack meat, sausage, fish, salad or cheese. Using the impressed folding pattern enables performing the press forming of the container with a greater depth of the container, as measured from rim to bottom, and with fewer fractures or other quality defects.

[0014] FIGURE 1 illustrates phases of container preparation. First, on the left, a planar, continuous board is illustrated which is used as material for manufacturing a container. The board is an example of a continuous element. By continuous it is herein meant that the element is of a single piece of material, as opposed to being a composite of plural elements attached to each other. On the right is the board of the image on the left, after pressforming to a container. As the material from which the board is made is not flexible, a fracture is generated during the press forming at the bottom of the container, and a part of the material along the rim has become wrinkled while press-forming with a mould. A fracture is more likely to occur when the material of the board used has a low breaking strain, as is the case, for example, in the case of paperboard. A fracture is also more likely to occur when material is translated, that is, displaced, more from the flat surface compared to when the translation in press forming, moulding or thermoforming is smaller in magnitude.

[0015] In paperboard, with mechanical or chemical fibre modification and suitable additives, or by creping, creasing or embossing that cause a partial breaking of inter-fibre joints, the elongation potential can be improved but the breaking strain still remains typically below 20%, limiting the achievable depth of cups, plates, trays and other 3D containers obtained in a thermoforming process using paperboard as material. Mechanical in-plane compaction is another way to increase the elongation potential of paperboard but this causes significant changes throughout the board structure and not just in local regions.

[0016] FIGURE IB illustrates phases of container manufacture in accordance with at least some embodiments of the present invention. Here again an element used as material is illustrated on the left, and the completed container is shown on the right. Unlike in the case of FIGURE 1A, the material on the left in FIGURE IB has been imparted with a folding pattern before press forming into the container shown in the right. An initial starting material of the process of FIGURE IB may be the material shown on the left-hand-side of FIGURE 1A. Thus a planar element may first be imparted with a folding pattern, and then press formed into shape.

[0017] In general, and not relating only to FIGURE IB, a folding pattern may be imparted to an element used as material in manufacture of a container by pleating, that is, pressing between two moulds of corresponding 3D shapes. Another option is folding by hand or by using roller nip compression. A difference between a folding pattern and other mechanical operations such as in-plane compaction, creping, creasing or embossing is that the depth of a folding pattern is least eight times a thickness of the element. Alternatively, the depth of the folding pattern may be at least twenty times the thickness of the element.

[0018] Differently from the case on the right in FIGURE 1A, in FIGURE IB there is no fracture, since the strain experienced by the material during press forming is significantly reduced due to the presence of the folding pattern. In particular, the strain is reduced by the folding pattern unfolding, at least partly, during the press forming. The unfolding is known as deployment in the art and represents a partial undoing of the folding pattern. This unfolding during press forming is relative to the extent of folding present in the material immediately prior to press forming. In other words, the extent of deployment increases during the press forming.

[0019] In other words, by applying a folding pattern to the material, its elongation potential can be drastically increased. During press forming, the induced stresses lead to an unfolding, or deployment, of the folding pattern, particularly in material regions where large local deformation is required. In this way, the local machine-direction, MD and crossmachine direction, CD, strains of the material may be maintained below the respective breaking strains even for larger macroscopic shape changes. In preliminary tests, this has been observed to lead to a reduction in material fractures and to less wrinkling near comer regions of the resulting container. The extent of deployment may increase also in areas where large local deformation is not needed, such as in areas close to the regions where large local deformation is needed. However, the extent of deployment during press forming is greatest where the deformation takes place, as will be described herein below in more detail.

[0020] The geometric scale and structural features of the folding pattern may be selected based on requirements of each application. This gives some adjustment possibilities as to how a detailed presentation of the eventual 3D container shape is produced. For most cases, a relatively dense folding pattern is optimal. The original folding pattern will remain visible in pressed form in the final container product as an additional design feature, distinguishing the product from other similar products, and acting as a stiffening structurefor the product, enabling lower raw material use, thus unlocking another technical effect of using the folding pattern. Yet further, compared to the in-plane compaction, creping, creasing or embossing, use of folding provides the beneficial technical effect that internal damage to the material occurs to a substantially lesser extent.

[0021] The Miura-ori folding pattern is one example of a folding pattern suitable for use in at least some embodiments of the present invention. Koryo Miura showed in 1970 that a perfectly flat, infinite plate naturally takes the form of a Miura-ori pattern when contracted in both planar directions simultaneously. This surface can be deployed (unfolded to remove the folding) simultaneously in orthogonal directions, which may be aided by the viscoelastic properties of the material itself. In other words, the Miura-ori folding pattern is an ideal pattern when a large deformation potential is sought in both machine and cross-machine directions of e.g. paperboard. Besides planar pattern density, the depth of folds in the material can be varied when they are finished on a production line. Deeper folds enable larger deformations during the press forming without fracturing, but at the same time the stiffness of the final product structure decreases. Therefore, it may beneficial to leave the folds of the folding pattern more shallow than would be possible technically. This may also help to have an even unfolding of the pattern under the compressive load of press forming.

[0022] While discussed herein primarily in terms of press forming, it is to be understood that this term is used herein to refer also to other compressive processes which might elsewhere be referred to as deep drawing, moulding, thermoforming, stamping, vacuum forming, hydroforming or airforming.

[0023] Prior to or after the press forming, a water-resistant coating layer may be attached on a surface of the container, such as on an inner surface, intended to receive a liquid or gel-like substance, such as soup. Such a water-resistant coating may be a plastic film or a liquid-retaining non-fossil fuel based film, such as a cellulose diacetate film, a poly lactic acid film, a starch based film or a recycled-PET based film.

[0024] In the Miura-ori pattern, crease patterns form a tessellation of the surface by parallelograms. In a first direction, the creases lie along straight lines, with each parallelogram forming the mirror reflection of its neighbour across each crease. In a second direction, the creases zigzag, and each parallelogram is the translation of its neighbour across the crease. Each of the zigzag paths of creases consists solely of mountain folds or of valley folds, with mountains alternating with valleys from one zigzag path to the next. Each of thestraight paths of creases alternates between mountain and valley fold. In Miura-ori, either three mountain folds and one valley fold or three valley folds and one mountain fold meet in each vertex.

[0025] The unfolding can be either partial or complete, which also affects the mechanical properties of the final 3D container, such as a soup plate, for example. The optimal geometrical pattern is such where the unfolding is complete in product regions where the material elongation largest, whereas in the other product regions the unfolding remains incomplete. However if a slight extent of folding remains undeployed the qualities of the resulting container are still good.

[0026] Even though Miura-ori is perhaps the most natural folding pattern to begin with, other similar tessellation folding patterns in origami science are also suitable for use with mouldable boards, such as cardboard or paperboard. The Yoshimura pattern and a Kresling pattern are examples of other suitable folding patterns.

[0027] FIGURE 2A illustrates an example container in accordance with at least some embodiments of the present invention. The axes in FIGURE 2A are spatial axes, the vertical axis denoting height of container 210 and the vertical axis denoting width of container 210. Container 210 has been manufactured of material into which the folding pattern described above has been imparted before press forming to obtain the illustrated container 210. While the example container of FIGURE 2A is symmetrical, also asymmetrical containers may be so produced. Container 210 comprises a rim 212, which may be circular, elliptical, square or rectangular, for example, and a central part 214, which acts as a bottom of container 210. A plane 220 is defined by the rim in that the rim is along this plane in space. In the illustrated example plane 220 is parallel to a plane defined by a bottom part of container 210, however embodiments of the herein disclosed container are not limited thereto, as the rim may be higher at one end of container 210 than another end, for example, causing these two planes to intersect. A height 222 of the container represents a spatial extent to which central part 214 has been translated from plane 220 in a direction perpendicular to plane 220, during the press forming.

[0028] Central part 214 may extend at least 10, 15 or 20 percent of a diameter or width of the container from plane 220 in the direction perpendicular to plane 220. In other words, height 222 may be at least 10, 15 or 20 percent of a diameter or width of the container. The repeating, pressed folding pattern may repeat at least 5, 10, 20, 100 or 500 times in onediameter or width of the container. The pressed folding pattern may be a crushed or at least partly crushed folding pattern. When the pattern repeats more, its dimensions are smaller, resulting in a smaller vertical geometrical variation to achieve the required enhancement in the fracture resistance when press forming. Overall the container may have a maximum dimension, such as width or height, of between 10 and 30 centimetres, between 10 and 40 centimetres or between 3 and 20 centimetres.

[0029] The folding pattern may have a depth of at least 8, 9 or 10 times the thickness of the element material. For example, the folding pattern may have a depth of between 8 and 500 times, between 9 and 1000 times, between 10 and 100 times, between 10 and 500 times, between 25 and 500 times or between 10 and 1000 times the thickness of the material. A further example is between 25 and 200 times the thickness of the material.

[0030] As noted above, the material used may be paperboard. Alternatively, however, the principles described herein provide benefit also to containers manufactured from other materials, such as plastic, polymer film, composite, cardboard, fibreboard or paper. In some cases, a metal sheet may also benefit from imparting a folding pattern to it prior to press forming, however metals may be designed with viscoelastic properties which withstand fracturing when press forming.

[0031] It is of interest that in parts of container 210 which are parallel to plane 220 the folding pattern is mechanically pressed during the press forming. However, as the press forming creates the 3D shape of container 210, the folding pattern is at least in part deployed in parts of the material where a distance of the material from plane 220 changes along an axis proceeding from rim 212 toward central part 214. In other words, it is the deviation and deformation in the vertical direction of FIGURE 2A which creates breaking stress in the material, and where this stress is present it is relieved, at least in part, by the unfolding, partial or complete, of the folding pattern. Unfolding may also take place, to a lesser extent, in other parts of the container during press forming owing to the dynamic nature of the pressing. In parts of container 210 where this unfolding does not occur, the folding pattern is merely pressed in the press forming. Where the unfolding is partial, the partially unfolded folding pattern is pressed in the press forming. In case the unfolding is complete in some part of container 210, the press forming will result in this part in a smooth or direct part of container 210 with little trace of the folding pattern.

[0032] Prior to the press forming, the folding pattern is in a state of partial deployment.Prior to the press forming, the extent of partial deployment may be constant throughout the material element which is press formed to form container 210. As described above, in parts of the material the folding pattern is deployed, at least in part, during the press forming, in other words, in these parts of the material the extent of deployment of the folding pattern increases during the press forming. As a result, after press forming, the extent of deployment of the folding pattern is greater in the parts of container 210 where the distance of the material from plane 220 changes along the axis proceeding from rim 212 toward central part 214.

[0033] FIGURE 2B illustrates a rate of change in accordance with at least some embodiments of the present invention. Here the horizontal axis corresponds to that of FIGURE 2A, namely, it is a width axis of container 210, which is in FIGURES 2A and 2B assumed to be rotationally symmetric about central part 214. The vertical axis in FIGURE 2B is a rate of change of a distance of the container’s material from the plane 220 defined by the rim 212 of the container 210, along an axis proceeding from the rim toward the central part. In terms of the container of FIGURE 2A, the rate of change is constant and zero unless the depth of the container changes along the horizontal axis, which corresponds here to a width of the container, as noted above. The two places where the rate of change becomes non-zero are the places 230 where the depth of the container changes, and these are the places where the press forming causes the folding pattern to deploy most. The deployment of the folding pattern reduces stress on the material of container 210, greatly reducing the risk of a fracture during the press forming.

[0034] Using the folding pattern as herein described provides several technical benefits. Firstly, it enables an industrial large-scale production of 3D-formed packaging from normal paperboard. This provides both sustainability and low cost for the product. Secondly, the folded board webs run in existing production lines when the density of the folding pattern is sufficiently high. Thirdly, mechanical properties of contained thus produces can be selected by geometrical details and folding / unfolding depth of the folding pattern together with material properties, such as paperboard grade. Fourthly, the folding pattern adds a visible design feature in the final container product that distinguishes it from other similar solutions. Finally, as noted also above, the folding pattern can also stiffen the product structure, enabling either a reduction in raw material use and / or a stiffer product.

[0035] FIGURE 3 is a flow graph of a method of manufacturing a container in accordance with at least some embodiments of the present invention.

[0036] Phase 310 comprises imparting a repeating folding pattern to a continuous planar element. Phase 320 comprises forming the container by employing a compressive process on the continuous planar element after the imparting of the repeating folding pattern, whereby a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container, wherein an extent of deployment of the folding pattern caused by the compressive process is greatest in parts of the element where a distance of the element’s material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part. In other words, the folding pattern may be pressed in first parts of the container and the folding pattern may be pressed and at least in part deployed in a second part of the container. The first parts may correspond, for example, to rim 212 and central part 214, and the second part may correspond to places 230 where the rate of change is nonzero.

[0037] As noted above, the folding pattern may have a depth of at least 8, 9 or 10 times the thickness of the element material. For example, the folding pattern may have a depth of between 8 and 500 times, between 9 and 1000 times, between 10 and 100 times, between 10 and 500 times, between 25 and 500 times or between 10 and 1000 times the thickness of the material. A further example is between 25 and 200 times the thickness of the material.

[0038] FIGs. 4A - 4G illustrate an example pressed cup. In this example process, a Miura-ork folded sack paper sheet is here pressed with a mechanical mold, such that edges of the ark were allowed to move during the pressing. The end result, FIGs. 4F - 4G, is a cup of about seven centimetres depth. The remaining folds could probably be completely removed by using a smaller Miura-ori geometry than in the example of FIGs. 4A - 4G.

[0039] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0040] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0041] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0042] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0043] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0044] The verbs “to comprise” and “to include” are used in this document as openlimitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

[0045] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.INDUSTRIAL APPLICABILITY

[0046] At least some embodiments of the present invention find industrial application in manufacture of containers, such as of paperboard.ACRONYMS LIST3D three-dimensionalCD cross-machine direction MD machine directionPET Polyethylene terephthalateREFERENCE SIGNS LIST

Claims

CLAIMS:

1. A container comprising:- a continuous element forming a body of the container, the element forming a three- dimensional shape of the container wherein a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container;- the element having a repeating, pressed folding pattern, wherein an extent of deployment of the folding pattern is greatest in parts of the element where a distance of the element’s material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part.

2. The container according to claim 1, wherein the folding pattern is a Miura-ori folding pattern, a Yoshimura pattern, a Kresling pattern or another folded origami tessellation pattern.

3. The container according to claim 1, wherein the central part extends at least 10, 15 or 20 percent of a diameter or width of the container from the plane defined by the rim of the container in the direction perpendicular to the plane defined by the rim of the container.

4. The container according to any of claims 1 - 3, wherein the repeating, pressed folding pattern repeats at least 5, 10, 20, 100 or 500 times in one diameter or width of the container.

5. The container according to any of claims 1 - 4, wherein a depth of the folding pattern, prior to being pressed, exceeds the thickness of the continuous element by a factor of between 8 and 500 times, between 9 and 1000 times, between 10 and 100 times, between 10 and 500, between 25 and 500 or between 10 and 1000 times.

6. The container according to any of claims 1 - 5, wherein the continuous element is one of the following: a continuous paperboard element, such as a cartonboard or containerboard element, a continuous plastic element, a continuous polymer film, a continuous composite, a continuous cardboard element, a continuous fibreboard element, a continuous nonwoven element or a continuous paper element.

7. The container according to any of clams 1 - 6, wherein the container has been manufactured by press-forming, deep drawing, moulding, thermoforming, stamping, vacuum forming, hydroforming or airforming to obtain the three-dimensional shape of the container and press the folding pattern.

8. The container according to any of claims 1 - 7, wherein the container has a maximum dimension of between 10 and 30 centimetres, between 10 and 40 centimetres or between 3 and 20 centimetres.

9. The container according to any of claims 1 - 8, wherein the container further comprises, on the continuous element, a water-resistant coating layer.

10. A method of manufacturing a container, comprising:- imparting a repeating folding pattern to a continuous planar element;- forming the container by employing a compressive process on the continuous planar element after the imparting of the repeating folding pattern, whereby a central part of the element is translated from a plane defined by a rim of the container in a direction perpendicular to the plane defined by the rim of the container, wherein an extent of deployment of the folding pattern caused by the compressive process is greatest in parts of the element where a distance of the element’s material from the plane defined by the rim of the container changes along an axis proceeding from the rim toward the central part.

11. The method according to claim 10, wherein the folding pattern is a Miura-ori folding pattern, a Yoshimura pattern, a Kresling pattern or another folded origami tessellation pattern.

12. The method according to claim 10 or 11, wherein a depth of the folding pattern, prior to being compressed, exceeds the thickness of the continuous element by a factor of between 10 and 100 times, between 10 and 500 times or between 10 and 1000 times.

13. The method according to any of claims 10 - 12, wherein the continuous element is one of the following: a continuous paperboard element, such as a cartonboard or containerboardelement, a continuous plastic element, a continuous polymer film, a continuous composite, a continuous cardboard element, a continuous fibreboard element, a continuous nonwoven element or a continuous paper element.

14. The method according to any of claims 10 - 13, wherein the compressive process comprises press-forming, deep drawing, moulding, thermoforming, stamping, vacuum forming, hydroforming or airforming.

15. The method according to any of claims 10 - 14, wherein the method further comprises providing a barrier layer on the continuous element, such as a water-resistant coating layer, a water vapour resistant coating layer, a moisture resistant coating layer or a grease resistant coating layer.

16. The method according to any of claims 10 - 15, further comprising using the container to pack fast-moving consumer goods, such as food packaging, such as packaging of meat, sausage, fish, salad or cheese.

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