Air-Laid Blanks and Cushioning Inserts

The present embodiments generally relate to air-laid blanks and methods for producing such air-laid blanks, and in particular air-laid blanks suitable for production of cushioning inserts.

With growing awareness for the environment and humanly induced climate change, the use of single-use plastic items and products has come more and more into question. However, despite this concern the use of these items and products has grown vastly with new trends in lifestyles and consumer habits of the last decade. One reason for this is that more and more goods are transported around the globe and these goods need protection against impact or shock. A common way of protecting the goods is to include cushioning elements or products, such as inserts of suitable form into the packaging. These can be made from different materials but are typically made from a foamed polymer, of which expanded polystyrene (EPS) is by far cheapest and most common. EPS is, however, one of the most questioned plastic materials and many brand owners are looking for more sustainable solutions for these packaging applications. Many countries have also begun to take legislative actions against single use plastic items and products, which increases the pressure to find alternative solutions.

More sustainable alternatives to polymer products exist today, such as inserts made by a process known as pulp molding, where a fiber suspension is sucked against a wire mold by vacuum. Another technique for forming such inserts is described in U.S. patent application no. 2010/0190020, European patent no. 1 446 286 and International application no. 2014/142714, which concern hot pressing of porous fiber mats produced by the process called air-laying into 3D structures with matched rigid molds or by membrane molding.

The above exemplified methods, however, produce cushioning inserts that are adapted to protect a particular product or goods. Hence, the design of the wire mold or the matched molds is selected based on the shape and size of the particular product or goods to be protected by the cushioning inserts. There is, however, a need for a generic cushioning insert that could be used to protect products and goods of various shapes and sizes and that can be manufactured using more environmentally friendly materials than polymer foams, such as EPS.

It is an objective to provide an air-laid blank that can be used to produce generic cushioning inserts.

This and other objectives are met by embodiments of the present invention.

The present invention is defined in the independent claims. Further embodiments of the invention are defined in the dependent claims.

An aspect of the invention relates to an air-laid blank comprising natural fibers and a polymer binder. The air-laid blank comprises a cushioning portion comprising a plurality of cavities extending into the air-laid blank and a frame portion lacking any cavities extending into the air-laid blank. The frame portion encircles the cushioning portion.

Another aspect of the invention relates to a method of producing an air-laid blank. The method comprises introducing natural fibers and a polymer binder and/or a mixture of the natural fibers and the polymer binder into at least one inlet of a forming head, transporting the natural fibers and the polymer binder and/or the mixture to an outlet of the forming head and capturing the natural fibers and the polymer binder and/or the mixture as an unbound air-laid web on a collector arranged in connection with the outlet of the forming head. The method also comprises applying gas pulses onto the unbound air-laid web to form a cushioning portion comprising a plurality of cavities extending into the unbound air-laid web. The cushioning portion is encircled by a frame portion of the unbound air-laid web and the frame portion lacks any cavities extending into the unbound air-laid web. The method further comprises heat treating the unbound air-laid web to at least partly melt the polymer binder and form an air-laid blank.

A further aspect of the invention relates to a method of producing an air-laid blank. The method comprises introducing natural fibers into at least one inlet of a forming head, transporting the natural fibers to an outlet of the forming head, and capturing the natural fibers as a web of natural fibers on a collector arranged in connection with the outlet of the forming head. The method also comprises applying gas pulses onto the web of natural fibers on the collector to form a cushioning portion comprising a plurality of cavities extending into the web of natural fibers. The cushioning portion is encircled by a frame portion of the web of natural fibers and the frame portion lacks any cavities extending into the web of natural fibers. The method further comprises applying a polymer binder onto the natural fibers and heat treating the web of natural fibers and the polymer binder to form an air-laid blank.

Yet another aspect of the invention relates to a cushioning insert made of an air-laid blank comprising natural fibers and a polymer binder. The cushioning insert comprises a cushioning portion comprising a plurality of cavities extending into the cushioning insert and a frame portion lacking any cavities extending into the cushioning insert. The frame portion encircles the cushioning portion.

The invention also relates to a packaging assembly comprising a packaging box having a bottom and at least one side wall attached to the bottom. The bottom and the at least one side wall define a packaging volume. The packaging assembly also comprises a first cushioning insert according to above arranged on the bottom of the packaging box with the plurality of cavities facing away from the bottom of the packaging box.

The present invention relates to air-laid blanks and cushioning inserts made from such air-laid blanks. The cushioning inserts are highly suitable for cushioning of packaged goods providing excellent shock absorbing and damping properties. The air-laid blanks and the cushioning inserts are designed to comprise a deformable cushioning portion comprising a plurality of cavities and where this cushioning portion adapts to various shapes and sizes of packaged goods. The cushioning portion is encircled by a frame portion lacking cavities and thereby providing structural integrity and strength to the air-laid blanks and cushioning inserts, while at the same time constituting a shock absorbing and damping protection for the packaged goods.

The present embodiments generally relate to air-laid blanks, methods, and apparatuses for producing such air-laid blanks, and in particular air-laid blanks suitable for production of cushioning inserts.

Air-laid blanks of the present embodiments are useful for production of cushioning inserts, also referred to as cushioning inlays or cushioning elements in the art, for packaging of products, articles, or goods. These cushioning inserts can then be used as more environmentally friendly replacements to corresponding cushioning inserts made of or from foamed polymers, for instance expanded polystyrene (EPS) or foamed polyurethane (PU). More sustainable alternatives to EPS-or PU-based cushioning inserts have been proposed in the art, such as in U.S. patent application no. 2010/0190020, European patent no. 1 446 286 and International application no. 2014/142714, which concern hot pressing of porous fiber mats produced by the process called air-laying into three dimensional inserts with matched rigid molds or by membrane molding. A significant limitation of these prior art inserts is that they are designed to protect a particular product or goods. Hence, the design of the matched molds is selected based on the shape and size of the particular product or goods to be protected by the cushioning inserts. This is in clear contrast to the present embodiments, which produce generic cushioning inserts that could be used to protect products and goods of various shapes and sizes. Such generic cushioning inserts are in particular desired by companies offering or packing a plurality of different products and goods, such as e-commerce companies.

The cushioning inserts of the present embodiments are formed from an air-laid blank comprising natural fibers and a polymer binder. An air-laid blank, sometimes also referred to as dry-laid blank, air-laid mat, dry-laid mat, air-laid web, or dry-laid web, is formed by a process known as air-laying, in which natural 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 blank 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. The air-laying process was initially described in U.S. Pat. No. 3,575,749.

is a cross-sectional view of a portion of an air-laid blank. The air-laying process typically produces air-laid blankswhere the vast majority of the natural fibers are oriented with their long axis close to parallel to the major surfaces,of the air-laid blank(x-y-plane in) with very little fibers oriented perpendicular to this plane, i.e., along the z-axis in. The fiber structure of the air-laid blank, thus, becomes almost stratified or layered in planes perpendicular to the z-axis. The stratified fiber orientation of air-laid blanksas shown inis good for the strength and stiffness properties of the air-laid blank, which thereby enables production of cushioning inserts with desired strength and stiffness properties from the air-laid blank.

An aspect of the invention relates to an air-laid blank, see the cross-sectional views inand top views in. The air-laid blankcomprises natural fibers and a polymer binder. The air-laid blankcomprises a cushioning portionand a frame portion. The cushioning portioncomprises a plurality of cavitiesextending into the air-laid blank, whereas the frame portionlacks any cavities extending into the air-laid blank. The frame portionfurther encircles the cushioning portion.

The air-laid blank, thus, comprises an internal portion, the cushioning portion, and a peripheral portion, the frame portion. The cushioning portioncomprises a plurality of cavitiesextending into the air-laid blankin this cushioning portion.illustrates one such cavity, whereasillustrates a plurality of cavitiesin the cushioning portion. The cavitiescan be viewed as pores or channels, in particular closed channels, extending from one of the major surfacesof the air-laid blanktowards the opposite major surfaceof the air-laid blank.

The cushioning portionof the air-laid blankcomprises less natural fiber material as compared to the frame portiondue to the presence of the plurality of cavities. This means that this cushioning portionof the air-laid blankis more deformable as compared to the stiffer frame portionand will thereby, in a cushioning insertA,B, see, formed from the air-laid blank, deform and adapt to the particular shape and size of products or goodsto be packaged in and protected by the cushioning insertA,B. The frame portionlacking the cavitiesthen provides structural integrity to the air-laid blankand the formed cushioning insertA,B. Furthermore, the frame portionat the same time constitutes a shock absorbing and damping protection for the packaged products or goods.

In an embodiment, the plurality of cavitiesextend through a portion of a thickness of the air-laid blankfrom a first major surfaceof the air-laid blanktowards a second, opposite major surfaceof the air-laid blank. In a particular embodiment, the plurality of cavities, however, does not extend through the whole thickness of the air-laid blankas shown in. Hence, the cavitiespreferably merely extend down to a portion of the thickness from the first major surface. In an embodiment, the cavities, or at least a majority of the plurality of cavities, extend down to a percentage of the thickness of the air-laid blankfrom the major surface. In a particular embodiment, this percentage is selected within an interval of from 25% up to 90%, preferably within an interval of from 35% up to 90%, more preferably within an interval of from 50% up to 90%, such as within an interval of from 60% up to 80%. In an illustrative, but non-limiting, example the cavities, or at least a majority thereof, extend down to from two thirds up to three quarters of the thickness of the air-laid blankfrom the first major surface.

In an embodiment, at least a majority of the plurality of cavitiesextend through merely a portion of the thickness of the air-laid blankbut not through the whole thickness. In such an embodiment, at least some of the cavitiesmay, though, extend through the whole thickness of the air-laid blankand thereby form channels through the air-laid blankfrom the first major surfaceto the second major surface. It is, though, generally preferred if all or at least a majority of the cavitiesmerely extend through a portion but not the whole thickness. The reason for this is that the cushioning portionwill then comprise a bottomcomprising the natural fibers and polymer binder that will provide cushioning support and protection for products and goods also from “below” of the lower cushioning insertA inand from “above” of the upper cushioning insertB.

The cavitiesmay extend substantially the same distance from the first major surfaceinto the air-laid blank, i.e., may have substantially the same depth. The embodiments are, however, not limited thereto. The cavitiesmay instead have different depths into the air-laid blankto thereby present a distribution of different depths. For instance, the depth of the cavitiesinto the air-laid blankcould be larger (deeper) in the central portion of the cushioning portionto provide the highest deformability in this central portion, whereas the depth of the cavitiesdecrease towards the frame portionto thereby provide more structural support and stiffness at the more peripheral parts of the air-laid blank. In such an embodiment, the depth of the plurality cavitiesgenerally decrease when traveling from the center of the cushioning portiontowards the frame portion. In another embodiment, the depth of the plurality cavitiesgenerally increase when traveling from the center of the cushioning portiontowards the frame portion

The plurality of cavitiesmay, as is further described herein, be achieved by applying gas pulses into the air-laid blank, or more correctly into an unbound or unbonded air-laid web, see, which is formed into the air-laid blankthrough heat treatment, and in particular into the first major surface,of the air-laid blankor unbound air-laid web. The depth of the cavitiesinto the air-laid blankis dependent on the force of the gas pulses. The depth may go from a shallow indentation in the first major surfaceto a deep pore.

In an embodiment, the force of the gas pulses is controlled to not form any channels through the whole thickness of the air-laid blankbut may form cavitiesin the air-laid blank. The force of the gas pulses may also be controlled to achieve different depths of the cavitiesin different parts of the cushioning portion.

Application of gas pulses causes a pile up of natural fiber materialonto the frame portionand partly also onto the partsof the cushioning portionbetween the cavitiesin the unbound air-laid webas schematically shown in. This piled up natural fiber materialwill, during the production process, be flattened out causing a densification of at least a partof the frame portionas shown in. This then means that an average density of the frame portionis higher than an average density of the air-laid blankprior to forming the plurality of cavitiesin the cushioning portion. In other words, an average density of air-laid material in the frame portionis higher than an average density of air-laid material in the cushioning portion. Hence, natural fiber materialblown away from the cushioning portionof the unbound air-laid webwill deposit at the frame portionand will then be pushed into the frame portion. This means that the corresponding frame portionof the air-laid blankwill thereby become denser, i.e., having a higher density of natural fibers, as compared to other parts of the air-laid blank. The higher density further improves the structural and stiffness properties of the frame portion.

The plurality of cavitiesin the cushioning portioncould be distributed to form a regular pattern, such as a pre-determined pattern, in the air-laid blank, such as a regular grid or matrix as shown in. It is also possible to form a denser distribution or pattern of the plurality of cavitiesas compared to a regular grid or matrix, which is shown in. In, the cavitiesare distributed in rows or columns that are displaced relative to each other to reduce the distance between adjacent cavitiesin the cushioning portion.illustrates a distribution of cavitieswith at least partly overlapping or near overlapping cavities. Such a distribution of cavitiessignificantly reduces the amount of air-laid material in the cushioning portionto thereby form pillars or protruding structures, see, in the cushioning portion. This in turn leads to a very deformable and flexible cushioning insertA that well adapts to the shape and size of any products or goodsplaced on the cushioning portionof the cushioning insertA, see.

In an embodiment, a distance between adjacent cavitiesin the cushioning portionis less than twice the largest side length or diameter of the adjacent cavities. In a particular embodiment, the distance is equal to or less than 1.75 times or 1.5 times the largest side length or diameter of the adjacent cavities.

In another embodiment, the distance between adjacent cavitiesin the air-laid blank, i.e., in the cushioning portionof the air-laid blank, is less than twice the average side length or average diameter of the plurality of cavities, or less than twice the largest side length or diameter if having differently sized cavities. In a particular embodiment, the distance is equal to or less than 1.75 times or 1.5 times the average side length or average diameter of the plurality of cavities, or equal to or less than 1.75 times or 1.5 times the largest side length or diameter if having differently sized cavities

The distance between adjacent cavitiesis defined as the center-to-center distance of the adjacent cavitiesparallel with the first and second major surfaces,. Hence, in an embodiment, the distance between the edges of adjacent cavitiesin the cushioning portionis preferably less than the largest side length or diameter of the adjacent cavities. In another embodiment, the distance between adjacent cavitiesin the cushioning portionis preferably less than the average side length or average diameter of the plurality of cavities, or less than the largest side length or diameter if having differently sized cavities.

It may in fact be possible to have even shorter distances between adjacent cavitiesin the cushioning portion. For instance, and as previously mentioned, cavitiesmay in fact at least partly overlap. In such an embodiment, each cavityof at least a portion of the plurality of cavitiesoverlaps with another cavityof at least the portion of the plurality of cavities. Such an embodiment is shown inwith overlapping cavities. In such a case, a plurality of protruding structureswill be formed by the remaining air-laid material, in between the overlapping cavities, which is further described herein.

The (center-to-center) distance between adjacent cavitiesmay be substantially the same throughout the cushioning portion. In another embodiment, one part of the cushioning portioncould have a denser distribution of cavitiesas compared to another part of the cushioning portion. For instance, the distance between adjacent cavitiescould be shorter at the center of the cushioning portionas compared to the peripheral parts of the cushioning portionclose to the frame portion. In such an embodiment, the (center-to-center) distance between adjacent cavitiesgenerally increases when traveling from the center of the cushioning portiontowards the frame portion.

The frame portionencircles the cushioning portionas shown inand thereby surrounds the cushioning portion. This means that the plurality of cavitiesare framed and encircled by a portion of the air-laid blankthat does not comprise cavities.

In an embodiment, a width of the frame portionis preferably at least 10 mm, preferably at least 15 mm, and more preferably at least 20 mm, such as at least 25 mm, at least 30 mm, at least 35 mm or at least 40 mm. Width of the frame portionas used herein corresponds to a distance from an edge of the air-laid blankto the cushioning portionas indicated by a W in.

In an embodiment, the width of the frame portionof the air-laid blankcorresponds to a percentage of the width of the air-laid blankand wherein this percentage is selected within an interval of from 2.5% up to 30%, preferably within an interval of from 2.5% up to 25%, and more preferably within an interval of from 5% up to 25%, such as within an interval of from 7.5% up to 25%, within an interval of from 10% up to 25%, or within an interval of from 10% up to 20%.

In an embodiment, the cushioning portioncomprises a bottomcomprising the natural fibers and the polymer binder and a plurality of protruding structurescomprising the natural fibers and the polymer binder. The protruding structuresmay then be separated from each other and are merely interconnected through the bottomof the cushioning portion. In such a case, the cavitiesare at least partly overlapping. In such an embodiment, the protruding structuresform pillars extending from the bottom. In another embodiment, the protruding structuresmay be interconnected with adjacent protruding structureswith (thin) walls of natural fibers and the polymer binder. In this latter embodiment, the adjacent cavitiesare not overlapping but are rather separated by a (thin) part of the air-laid material. It is also possible to combine these embodiments, i.e., having both separate protruding structuresand protruding structuresinterconnected with (thin) walls and thereby a combination of overlapping cavitiesand non-overlapping cavities.

In an embodiment, the cavitiesmay have an average extension, such as average side length or average diameter, parallel with the first and second major surfaces,that preferably does not exceed 100 mm, preferably does not exceed 75 mm, and more preferably does not exceed 50 mm, such as being equal to or below 40 mm, equal to or below 30 mm or equal to or below 25 mm.

The cavitiesmay have substantially the same extension, such as side length or diameter, or the air-laid blankcould comprise differently sized cavitieshaving different extensions, such as different side lengths or diameters. Furthermore, the overall shape of the cavitiescould be substantially the same, such as having a cylinder shape as an illustrative, but non-limiting, example. The embodiments are, however, not limited thereto. Hence, the cushioning portionof the air-laid blankcould comprise cavitieswith different overall shapes and forms.

It is generally preferred if the natural fibers in the air-laid blankare short at least as compared to the fibers in glass or mineral wool. Having comparatively short natural fibers promotes formation of a porous air-laid blank. In more detail, such short natural fibers are suitable for usage in embodiments of the present invention applying gas pulses onto the air-laid blankto produce cavitiesin the cushioning portionof the air-laid blank.

Length of fibers, such as natural 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 16065-1:2014 Pulps—Determination of fibre length by automated optical analysis—Part 1: Polarized light method or ISO 16065-2:2014 Pulps—Determination of fibre length by automated optical analysis—Part 2: Unpolarized light method.

In an embodiment, the natural fibers have a length weighted average fiber length of up to 10 mm, preferably of up to 8 mm, more preferably of up to 6 mm, and most preferably up to 5 mm. In a particular embodiment, the natural fibers have a length weighted average fiber length selected within an interval of from 1 mm up to 10 mm, preferably selected within an interval of from 1 mm up to 8 mm, more preferably selected within an interval of from 1 mm up to 6 mm, and most preferably selected within an interval of from 1 mm up to 5 mm.

It is also possible to include a minor portion of longer fibers having a length weighted average fiber length of 10 mm or more.

In an embodiment, the air-laid blankcomprises the natural fibers at a concentration of at least 70% by weight of the air-laid blankand the polymer binder at a concentration selected within an interval of from 2.5 up to 30% by weight of the air-laid blank.

In a preferred embodiment, the air-laid blankcomprises the natural 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 blank. In some applications, even higher concentrations of the natural fibers may be used, such as at least 87.5%, or at least 90%, at least 92.5%, at least 95% or at least 97.5% by weight of the air-laid blank.

In some embodiments, the air-laid blankcomprises the polymer binder at a concentration selected within an interval of from 5 up to 30% by weight of the air-laid blank, preferably within an interval of from 10 up to 25%, such as from 12.5 up to 22.5% by weight of the air-laid blank, or within an interval of from 15 up to 20% by weight of the air-laid blankor within an interval of from 17.5 up to 22.5% by weight of the air-laid blank.

In other embodiments, the air-laid blankcomprises the polymer binder at a concentration selected within an interval of from 2.5 up to 15% by weight of the air-laid blank, preferably within an interval of from 2.5 up to 12.5% by weight of the air-laid blank, more preferably within an interval of from 2.5 up to 10% by weight of the air-laid blank, such as within an interval of from 2.5 up to 7.5% by weight of the air-laid blank.

In an embodiment, the natural fibers are or comprise wood fibers. In an embodiment, the natural fibers are or comprise cellulose and/or lignocellulose fibers. Hence, in an embodiment, the natural fibers contain cellulose, such as in the form of cellulose and/or lignocellulose, i.e., a mixture of cellulose and lignin. The natural fibers may also contain lignin, such as in the form of lignocellulose. The natural fibers may additionally contain hemicellulose. In a particular embodiment, the natural fibers are cellulose and/or lignocellulose pulp fibers produced by chemical, mechanical and/or chemi-mechanical pulping of softwood and/or hardwood. For instance, the cellulose and/or lignocellulose pulp fibers are in a form selected from the group consisting of sulfate pulp, sulfite pulp, thermomechanical pulp (TMP), high temperature thermomechanical pulp (HTMP), mechanical fiber intended for medium density fiberboard (MDF-fiber), chemi-thermomechanical pulp (CTMP), high temperature chemi-thermomechanical pulp (HTCTMP), and a combination thereof.

The natural fibers, such as cellulose and/or lignocellulose pulp fibers, may be bleached or unbleached.

The natural fibers can also be produced by other pulping methods and/or from other cellulosic or lignocellulosic raw materials, such as flax, jute, hemp, kenaf, bagasse, cotton, bamboo, straw, or rice husk. It is also possible to use natural fibers that are a mixture of fibers from different raw materials, such as a mixture of wood and any of the materials mentioned above.

The air-laid blankmay also comprise a minor portion of synthetic material or fibers that are mixed with the natural fibers. Such synthetic material or fibers that may be mixed with the natural fibers include, for instance, glass or mineral wool, and/or carbon fibers. Any such synthetic material or fibers may be added at an amount of no more than 10% (w/w) of the air-laid blank 10, preferably no more than 8% (w/w), such as no more than 6% (w/w), or preferably no more than 4% (w/w) of the air-laid blank.