EP4688297A1

EP4688297A1 - Production of bonded air-laid blanks

Info

Publication number: EP4688297A1
Application number: EP24784484.8A
Authority: EP
Inventors: Martin MALMQVIST; Maria TÖRNBLOM; Julia BROSZAT; Elisabeth BERGVALL
Original assignee: Stora Enso Oyj
Current assignee: Stora Enso Oyj
Priority date: 2023-04-04
Filing date: 2024-03-27
Publication date: 2026-02-11
Also published as: SE2330150A1; SE547727C2; WO2024209310A1

Abstract

A method and system (100) for producing a bonded air-laid blank (10). Natural fibers and a polymer binder are introduced into a forming head (110) and captured as an unbonded air-laid web (20) on an air- permeable conveyor (120) arranged in connection with an outlet (113) of the forming head (110). The unbonded air-laid web (20) is heated to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank (10). Non-bonded natural fibers are removed from at least one main surface (12, 14) of the bonded air-laid blank (10) by at least one vacuum suction head (162, 164) of an inline vacuum suction system (160). The bonded air-laid blanks (10) produced by the method and system (100) generate less lint or dust in the form of non-bonded natural fibers.

Description

PRODUCTION OF BONDED AIR-LAID BLANKS

TECHNICAL FIELD

The present invention generally relates to bonded air-laid blanks, and in particular to a method and system for producing such bonded air-laid blanks.

BACKGROUND

An air-laid blank, sometimes also referred to as dry-laid or dry-formed blank, air-laid mat, or dry-laid mat, is formed by a process known as air-laying, in which natural fibers and a polymer binder are mixed with air to form a porous fiber mixture deposited onto a support and consolidated or bonded by heating. During the heating the natural fibers are bonded by the polymer binder. The air-laid blank is characterized by being porous, having the character of an open cell foam. Air-laid blanks are produced in a so-called dry forming method, i.e., generally without addition of water. The air-laying process is described in, for instance, U.S. patent no. 6,233,787.

In the production of air-laid blanks, non-bonded natural fibers present on the air-laid blanks or detached therefrom during production, are perceived as lint or dust. Such lint or dust may constitute an aesthetic problem for products formed from the air-laid blanks. Furthermore, in larger quantities, such dust can cause inconvenience and irritations for persons handling the air-laid blanks during and following production.

U.S. patent no. 3,994,047 discloses an apparatus for air laying fibers to form a composite pad. The apparatus comprises a pair of forming heads and a dual carrier system to form two separate layers of the composite pad. A so-called removing means is arranged immediately upstream of the position at which the two separate layers are combined to form composite pads. This removing means operates similar to a vacuum cleaner to shear off peaks of excess material in the separate layers before the layers are joined to form the composite pad.

U.S. publication no. 2002/0066517 discloses webs made of cellulose fibers admixed with thermobonding fibers. The surfaces of the webs are sealed by addition of a binder foam sprayed onto the surfaces.

There is a need to produce air-laid blanks with less lint or dust present on or detaching from outer surfaces of the produced air-laid blanks. SUMMARY

It is a general objective to provide a method and system of producing bonded air-laid blanks having improved linting characteristics.

These and other objectives are met by embodiments as disclosed herein.

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 a method of producing a bonded air-laid blank. The method comprises introducing natural fibers and a polymer binder into a forming head and capturing the natural fibers and the polymer binder as an unbonded air-laid web on an air-permeable conveyor arranged in connection with an outlet of the forming head. The method also comprises heating the unbonded air-laid web to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank. The method further comprises removing non-bonded natural fibers from at least one main surface of the bonded air-laid blank by at least one vacuum suction head of an inline vacuum suction system.

Another aspect of the invention relates to a system for producing a bonded air-laid blank. The system comprises a forming head comprising at least one inlet configured to receive natural fibers and a polymer binder, and an outlet. The system also comprises an air-permeable conveyor arranged in connection with the outlet to capture the natural fibers and the polymer binder as an unbonded air-laid web. The system also comprises a heating device arranged to heat the unbonded air-laid web to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank. The system further comprises an inline vacuum suction system comprising at least one vacuum suction head arranged to remove nonbonded natural fibers from at least one main surface of the bonded air-laid blank.

Generally, in the production of bonded air-laid blanks, non-bonded natural fibers present on the bonded air-laid blanks or detached therefrom during production are perceived as lint or dust. Such lint or dust may constitute an aesthetic problem for products formed from the bonded air-laid blanks. Furthermore, in larger quantities, such dust can cause inconvenience and irritations for persons handling the bonded air-laid blanks during and following production. The lint or dust may also cause problems for electronics and electronic equipment if, for instance, the bonded air-laid blank is employed as cushioning or insulation insert for packaging the electronics or electronic equipment. The present invention removes such nonbonded natural fibers from the bonded air-laid blank during production by an inline vacuum suction system leading to a substantial improvement of the linting behavior of the bonded air-laid blank and products produced therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:

Fig. 1 A is a perspective view of a bonded air-laid blank according to an embodiment;

Fig. 1 B is side-view of a portion of a bonded air-laid blank according to an embodiment;

Fig. 2 is a flow chart illustrating a method of producing an air-laid blank according to an embodiment;

Fig. 3 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to an embodiment;

Fig. 4 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to another embodiment;

Fig. 5 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to a further embodiment;

Fig. 6 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to yet another embodiment;

Fig. 7 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to a further embodiment;

Fig. 8 is a flow chart illustrating an additional, optional step of the method in Fig. 2 according to yet another embodiment;

Fig. 9 is a schematic illustration of a system for producing an air-laid blank according to an embodiment; Fig. 10 is a schematic illustration of a system for producing an air-laid blank according to another embodiment;

Fig. 11 is a schematic illustration of a system for producing an air-laid blank according to a further embodiment;

Fig. 12 is a schematic illustration of a system for producing an air-laid blank according to yet another embodiment;

Fig. 13 is a schematic illustration of a system for producing an air-laid blank according to another embodiment;

Fig. 14 is a schematic illustration of a system for producing an air-laid blank according to a further embodiment;

Fig. 15 schematically illustrates an embodiment of the vacuum suction heads in a side view;

Fig. 16 schematically illustrates another embodiment of the vacuum suction heads in a perspective view;

Fig. 17 schematically illustrates a further embodiment of the vacuum suction heads in a perspective view;

Fig. 18. schematically illustrates yet another embodiment of the vacuum suction heads in a perspective view;

Fig. 19 is a schematic illustration of a system for producing an air-laid blank according to another embodiment; and

Fig. 20 is a schematic illustration of a system for producing an air-laid blank according to a further embodiment.

DETAILED DESCRIPTION

The present invention generally relates to bonded air-laid blanks, and in particular to a method and system for producing such bonded air-laid blanks. Bonded air-laid blanks are characterized by being porous, having the character of an open cell foam. They are resilient and have great damping and insulation capacity. These characteristics of bonded airlaid blanks make the material suitable to replace polymer foams and formed in-place fossil-based materials in packaging solutions. A common way of protecting goods is to include cushioning elements or products, such as inserts of suitable form into the packaging. These cushioning elements or products 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. Bonded air-laid blanks are useful for production of more environmentally friendly replacements to corresponding cushioning inserts made of or from foamed polymers, for instance EPS or foamed polyurethane (PU). Bonded air-laid blanks also find uses where there is a need for providing insulation, such as thermal or sound insulation. Illustrative, but non-limiting examples, of such applications include thermal insulation of heated or cold food products or other articles that need to be kept within defined temperature ranges. Furthermore, sound absorbing panels or elements could be produced from the bonded air-laid blanks.

In the production of bonded air-laid blanks, non-bonded natural fibers present on or in the bonded air-laid blanks or detached therefrom during production are perceived as lint or dust. Such lint or dust may constitute aesthetic problems for products formed from the bonded air-laid blanks. Furthermore, in larger quantities, such dust can cause inconvenience and irritations for persons handling the bonded air-laid blanks during and following production. The lint or dust may also cause problems for electronics and electronic equipment if these are packaged using cushioning elements or inserts made from the bonded air-laid blanks. In such a case, non-bonded natural fibers may cause short circuits if reaching the electronic circuitry within the electronics or electronic equipment. Such non-bonded natural fibers might also be a risk during operation of the electronics or electronic equipment causing heat development that might ignite the non-bonded natural fibers.

It has been found that removal of non-bonded natural fibers from the bonded air-laid blank during production by an inline vacuum suction system, also referred to as inline vacuum cleaning system herein, leads to a substantial improvement of the linting behavior of the bonded air-laid blank and products produced therefrom.

The present invention therefore relates to a method of producing a bonded air-laid blank 10, see Figs. 1A, 1 B, 2, 9-14. The method comprises introducing, in step S1 , natural fibers and a polymer binder into a forming head 110. The natural fibers and the polymer binder are captured in step S2 as an unbonded air-laid web 20 on an air-permeable conveyor 120 arranged in connection with an outlet 113 of the forming head 110. The method also comprises heating, in step S3, the unbonded air-laid web 20 to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank 10. According to the invention, non-bonded natural fibers are removed in step S4 from at least one main surface 12, 14 of the bonded air-laid blank 10 by at least one vacuum suction head 162, 164 of an inline vacuum suction system 160.

The bonded air-laid blank 10 as produced in the method of Fig. 2 has significantly less non-bonded natural fibers following the fiber removal by the inline vacuum suction system 160 in step S4 as compared to the bonded air-laid blank 10 upstream of the inline vacuum suction system 160. This in turn means that the bonded air-laid blank 10 and products produced therefrom, such as cushioning inserts or other packaging elements, will contain less lint and dust. The cleaned bonded air-blank 10 of the invention has a reduced tendency to contaminate packaged goods and other products, including food or beverages, in contact with the bonded air-laid blank 10 or products produced therefrom with such lint and dust. These effects, as achieved by the bonded air-laid blank 10, not only solve any aesthetic problems caused by the lint and dust, but also reduce the risk of any inconvenience that could otherwise be caused by inhaling fine fiber-based lint and dust. Furthermore, the risk of problems with non-bonded natural fibers contaminating sensitive equipment, such as electronics, is reduced by the invention.

U.S. patent no. 3,994,047 discloses an apparatus and process for the production of separate layers that are combined and joined to form a composite pad. A removing means is arranged upstream of the joining process to shear off peaks of excess material in the separate layers. This removing means is, thus, arranged to smooth out the joining surfaces of the two layers to facilitate an even joint between them. This means that only joining surfaces are exposed to the removing means and these joining surfaces will form the internal joint in the composite pad. As a consequence, the external surfaces of the composite pad are not subject to the removing means. This means that the final composite pad will contain nonbonded fiber material on the outer surfaces of the composite pad. This means that bonded air-laid blanks 10 produced according to the invention have significant advantages as compared to the composite pads produced according to U.S. patent no. 3,994,047 in terms of less lint or dust from the surfaces 12, 14 of the bonded air-laid blanks 10.

The vacuum suction system 160 comprising at least one vacuum suction head 162, 164 and used to remove non-bonded natural fibers from the bonded air-laid blank 10 in step S4 is a so-called inline vacuum suction system 160. Inline vacuum suction system 160 as used herein means that the vacuum suction system 160 is arranged to be used within the production process of the bonded air-laid blank 10. Hence, as shown in Figs. 9-14 the inline vacuum suction system 160 forms part of the system 100 for producing a bonded air-laid blank 10 and thereby part of the production line for the bonded air-laid blank 10. This differs from a so-called offline vacuum suction system, which is instead arranged outside of the system 100 and production line, such as at another site or facility or at another location within the production site, to be used to clean already produced bonded air-laid blanks 10 after they have been transported from the system 100 and production line.

The inline vacuum suction system 160 is used in step S4 to remove non-bonded natural fibers from at least one main surface 12, 14 of the bonded air-laid blank 10. As is shown in Fig. 1A, a bonded air-laid blank 10 is typically in the form of a sheet having a length L, a width W and a thickness T. In such a case, the main surfaces 12, 14 of the bonded air-laid blank 10 are the two surfaces defined by the length L and the width W. The main surfaces 12, 14 are substantially parallel with the upper surface of the air- permeable conveyor 120 (Figs. 9-14) or a downstream conveyor 180 (Figs. 10, 12) with one of the main surfaces 14 facing the air-permeable conveyor 120 (Figs. 9-14) or the downstream conveyor 180 (Figs. 10, 12) and being positioned thereon during production of the bonded air-laid blank 10 and with the other main surface 12 facing in a direction opposite to the air-permeable conveyor 120 (Figs. 9-14) or the downstream conveyor 180 (Figs. 10, 12).

The main surfaces 12, 14 of the bonded air-laid blank 10 have a respective surface area that is typically substantially larger than the surface area of the longitudinal sides 11 or end sides 13 of the bonded airlaid blank 10.

The natural fibers and the polymer binder are introduced in step S1 into a forming head 110, also referred to as forming chamber in the art. The natural fibers and the polymer binder are input or introduced into the forming head 110 as one or more discrete input streams and/or as one or more mixed input streams at one or more inlets 111 . For instance, the forming head 110 may, such as in connection with its upper end 112 or further down in the forming head 110, comprise one stream inlet for the natural fibers and one stream inlet for the polymer binder. In another embodiment, the forming head 110 comprises multiple stream inlets for the natural fibers and one stream inlet for the polymer binder, one stream inlet for the natural fibers and multiple stream inlets for the polymer binder or multiple stream inlets for the natural fibers and multiple stream inlets for the polymer binder. In these illustrative examples, the natural fibers and the polymer binder are mixed and blended during the passage through the forming head 110 ultimately forming an unbonded air-laid web 20 on the air-permeable conveyor 120. Instead of, or as a complement to, having one or more input streams for the natural fibers and/or one or more input streams for the polymer binder, a pre-formed mixture of the natural fibers and the polymer binder may be introduced into the forming head 1 10 at one or multiple stream inlets 111. Hence, in an embodiment, step S1 in Fig. 2 comprises introducing a mixture of the natural fibers and the polymer binder into at least one inlet 1 11 of the forming head 110.

The forming head 110 may include equipment arranged inside the forming head 110 to promote separation and mixing of the natural fibers and the polymer binder, and/or the mixture thereof during the passage through the forming head 110. Such equipment may comprise, for instance, rolls with interlocking spikes, one or more drums, such as slit drums, and/or one or more strainers.

The natural fibers and the polymer binder and/or the mixture thereof are(is) transported to the forming head 110 by air and enter(s) the forming head 110 in the at least one inlet 111 , such as arranged in connection with the upper end 112 of the forming head 110, or further down in the forming head 110. The natural fibers and the polymer binder and/or the mixture thereof then pass(es) through the forming head 110 to the outlet 113, such as arranged in connection with a lower end 114 of the forming head 110. The natural fibers and the polymer binder and/or the mixture are(is) then captured on the air-permeable collector 120. In an embodiment, the natural fibers and the polymer binder and/or the mixture are(is) captured at least partly by a vacuum, i.e., an air suction or under-pressure, applied across the air- permeable collector 120 that is disposed in connection with the outlet 113 of the forming head 110. Hence, in an embodiment, the method of Fig. 2 preferably comprises an additional step S10 as shown in Fig. 3. The method then continues from step S1 in Fig. 2. A next step S10 comprises passing the natural fibers and the polymer binder to the outlet 113 of the forming head 110 while applying a gas suction through the air-permeable conveyor 120 in connection with the outlet 113 of the forming head 110.

Such a gas suction or vacuum is applied through the air-permeable conveyor 120. The gas suction or vacuum applied across the air-permeable conveyor 120, thus, draws the natural fibers and the polymer binder down onto the air-permeable conveyor 120. For instance, the air-permeable conveyor 120 could comprise a plurality of openings, through holes or channels allowing air to be sucked or drawn through the air-permeable conveyor 120. As an illustrative, but non-limiting, example, the air-permeable conveyor 120 could be a mesh conveyor, a wire conveyor or a belt conveyor with a belt comprising a plurality of minute through holes. However, any such openings are preferably small enough to prevent the natural fibers and the polymer binder from passing through the air-permeable conveyor 120. Hence, the natural fibers and the polymer binder are instead deposited as a mixture onto the air-permeable conveyor 120 in the form of an unbound air-laid web 20.

In an embodiment, the air-permeable conveyor 120 is an endless air-permeable conveyor. As an example, the air-permeable conveyor 120 could comprise an endless air-permeable conveyor belt 122 running along driver rollers 124, 126 as shown in Figs. 9-14. An endless air-permeable conveyor belt 122 is an air-permeable conveyor belt 122 that has been made into an endless air-permeable belt 122 without joints. Such an endless air-permeable conveyor belt 122 is also referred to as jointless air-permeable conveyor belt in the art.

In an embodiment, step S3 comprises heat treating the unbound air-laid web 20 to at least partly melt the polymer binder and form the bonded air-laid blank 10. The heat treatment applied in step S3 performs a bonding operation, in which the unbound air-laid web 20 is introduced into or otherwise passes a heating device 140, also referred to as a bonding oven, see Figs. 9-14, where heat, such as in the form of heated or hot air, is blown into, sucked into and/or circulated through the unbound air-laid web 20 to melt or partially melt the polymer binder. The polymer binder thereby becomes tacky and adheres to the natural fibers and, thus, holds the fiber material together and thereby results in a bonded air-laid blank 10.

The heat treatment of step S3 causes at least a partial melting of the polymer binder to thereby become tacky and adhere to the natural fibers in the unbound air-laid web 20. As a consequence, the natural fibers and polymer binder hold together and form the bonded air-laid blank 10.

The heating or bonding operation in step S3 may also comprise, and/or be accompanied by, a densification to create a larger number of binding points in the fiber structure and, thus, a stronger and denser bonded air-laid blank 10. Such a densification operation could be applied either before the bonded air-laid blank 10 has been allowed to cool after the heating device 140 or upon renewed heating, such as in a heated calender. It is also possible to perform the densification operation in the heating device 140, e.g., as a combined heating and densification operation. In this latter case, step S3 comprises heat treating the unbound air-laid web 20 to at least partly melt the polymer binder and simultaneously applying pressure onto the unbound air-laid web 20 to form the bonded air-laid blank 10. The densification can include various types of operations including, but not limited to, calendering and/or pressing operations. The inline vacuum suction system 160 is provided in the system 100 to remove non-bonded natural fibers from at least one main surface 12, 14 of the bonded air-laid blank 10 following the heating and bonding in step S3.

The heating as applied in step S3 will partly melt the polymer binder to become tacky and adhere to the natural fibers in the unbounded air-laid web 20 to thereby form the bonded air-laid blank 10. Most of the natural fibers in the unbounded air-laid web 20 will thereby be bonded together by the polymer binder forming the porous, open cell foam like structure of the bonded air-laid blank 10. However, some natural fibers will not be bonded by the polymer binder and thereby remain loose within the bonded air-laid blank 10. Such non-bonded fibers may be present both at the surfaces 11, 12, 13, 14 of the bonded air-laid blank 10 but also within the fiber structure or matrix of the bonded air-laid blank 10. The latter ones, i.e., non-bonded fibers within the bulk of the bonded air-laid blank 10, are usually physically trapped therein by the fiber structure or matrix of the bonded fibers. Hence, those non-bonded fibers most often remain physically trapped within the bulk of the bonded air-laid blank 10 even though they are not efficiently bonded by the polymer binder. However, there is generally a distribution in the dimensions of the natural fibers introduced in step S1 especially if the natural fibers are produced by mechanical pulping processes. Furthermore, some natural fibers may be broken into smaller parts during the production of the bonded air-laid blank 10. Such shorter fibers or indeed fiber particles or debris, also referred to as fines material in the art, may then, if not bonded by the polymer binder following step S3, escape through the fiber structure of the bonded air-laid blank 10. Additionally, natural fibers may be at least partly bonded by the polymer binder, but the bond might be far from sufficient so that such natural fibers become detached from the fiber structure of the bonded air-laid blank 10. This is in particular a problem for the natural fibers present at the surfaces 11, 12, 13, 14 of the bonded air-laid blank 10 as these surface fibers generally have fewer bonds, formed by the polymer binder, to neighboring natural fibers in the bonded air-laid blank 10 as compared to natural fibers present within the bulk of the bonded air-laid blank 10. The fiber particles, fines material or debris will together with detached natural fibers and non-bonded natural fibers at the surfaces H , 12, 13, 14 or within a shallow depth from the surfaces H , 12, 13, 14 be perceived as lint or dust that may constitute an aesthetic problem for products formed from the bonded air-laid blank 10. Furthermore, in larger quantities, such dust can cause inconvenience and irritations for persons handling the bonded air-laid blank 10 during and following production. Accordingly, the present invention solves these problems by removing such non-bonded natural fibers from at least one main surface 12, 14 of the bonded air-laid blank 10 in step S4. Non-bonded natural fibers as used herein thereby constitute not only non-bonded natural fibers, or natural fibers having insufficient bond to neighboring natural fibers in the bonded air-laid blank 10 but also fines materials, such as short fibers or fiber particles. Non-bonded natural fibers as removed in step S4 are as described above and may thereby include, for instance, non-bonded natural fibers at, or at shallow depth from, the surfaces 11 , 12, 13, 14 of the bonded air-laid blank 10, detached natural fibers, fines material, broken fibers and fiber particles.

In an embodiment, non-bonded natural fibers are removed from one main surface 12, 14 of the bonded air-laid blank 10 in step S4 by a vacuum suction head 162, 164 of the inline vacuum suction system 160. Figs. 9-11 , 13 illustrate such an approach, in which the inline vacuum suction system 160 comprises one vacuum suction head 162 arranged to remove non-bonded natural fibers from one main surface 12 of the bonded air-laid blank 10. In Figs. 9-11 , 13, a single such vacuum suction head 162 is arranged to remove non-bonded natural fibers from the main surface 12 facing away from the air-permeable conveyor 120. It is also possible to have multiple, i.e., at least two, consecutive vacuum suction heads 162, 162' arranged to remove non-bonded natural fibers from this main surface 12 as shown in Fig. 14. In such a case, the multiple vacuum suction heads 162, 162' are arranged one after another along the air- permeable conveyor 120.

In a particular embodiment, step S4 of Fig. 2 comprises removing, while the bonded air-laid blank 10 is positioned with a second main surface 14 of the bonded air-laid blank 10 on the air-permeable conveyor 120, see Figs. 9, 11 , 13-14, or a downstream conveyor 180, see Fig. 10, non-bonded natural fibers from a first, opposite main surface 12 of the bonded air-laid blank 10.

This means that the at least one vacuum suction head 162, 162' has direct access to the first main surface 12 of the bonded air-laid blank 10 and the inline vacuum suction system 160 may in fact be in direct, physical contact with the first main surface 12 of the bonded air-laid blank 10, such as through upstream and downstream distance elements 30, 40, which is further discussed herein in connection with Figs. 15 and 16.

In another embodiment, one or multiple vacuum suction heads 164 could be arranged to remove nonbonded natural fibers from the main surface 14 of the bonded air-laid blank 10 facing the air-permeable conveyor 120 or a downstream conveyor 180, see Fig. 12. The at least one vacuum suction head 164 is then arranged on the "underside” of the bonded air-laid blank 10 passing over and past the at least one vacuum suction head 164. In the above-described embodiments, the inline vacuum suction system 160 is provided in the system 100 to remove non-bonded natural fibers from one of the main surfaces 12, 14 of the bonded air-laid blank 10.

This approach may be sufficient in particular if one main surface 12, 14 of the bonded air-laid blank 10 will be exposed in the product made from the bonded air-laid blank 10. For instance, a cushioning insert could be produced from the bonded air-laid blank 10 and designed to fit within a package, such as a box. In such a case, one of the main surfaces of the cushioning insert may mainly face walls of the box whereas the opposite main surface of the cushioning insert faces the goods or article to be put into the box and protected by the cushioning insert. In such an example, it may be sufficient to remove nonbonded natural fibers from one of the main surfaces 12, 14 of the bonded air-laid blank 10. The other main surface of the bonded air-laid blank 10 could then be left unprocessed in step S4 since that surface is intended to face walls of the box and will thereby not be in contact with the goods or article or the user.

In another embodiment, step S4 of Fig. 2 comprises removing non-bonded natural fibers from a first main surface 12 of the bonded air-laid blank 10 by a first vacuum suction head 162 of the inline vacuum suction system 160 and removing non-bonded natural fibers from a second, opposite main surface 14 of the bonded air-laid blank 10 by a second vacuum suction head 164 of the inline vacuum suction system 160. Hence, in a preferred embodiment, non-bonded fibers are removed from both main surfaces 12, 14 of the bonded air-laid blank 10 by different vacuum suction heads 162, 164 arranged on either side of the bonded air-laid blank 10 as shown in Fig. 12. This means that non-bonded fibers are removed from both main surfaces 12, 14 of the bonded air-laid blank 10. As a consequence, a more effective removal of non-bonded natural fibers is achieved in this embodiment as compared to merely removing non-bonded natural fibers from one of the main surfaces 12, 14.

In the above-described embodiments, one or multiple consecutive vacuum suction heads 162, 164 could be arranged to remove non-bonded fibers from one or both main surfaces 162, 164. If multiple such vacuum suction heads 162, 162' are arranged to remove non-bonded natural fibers from one main surface 12 of the bonded air-laid blank 10 then these multiple vacuum suction heads 162, 162' are preferably arranged one after another. For instance, two such vacuum suction heads 162, 162' could be arranged one after another with the first one being an upstream vacuum suction head 162 and the second one being a downstream vacuum suction head 162'. Upstream and downstream as used herein indicates that the first or upstream vacuum suction head 162 is arranged upstream of the second or downstream vacuum suction head 162', and the second or downstream vacuum suction head 162' is, thus, arranged downstream of the first or upstream vacuum suction head 162.

Upstream and downstream as used herein relate to the general direction of movement of the air-laid web 20 and the bonded air-laid blank 10 during production, i.e., from the forming head 110 towards the inline vacuum suction system 160.

If more than two vacuum suction heads 162, 162' are arranged on the same side relative the bonded airlaid blank 10 then one or more intermediate vacuum suction heads could be arranged between the upstream and downstream vacuum suction heads 162, 162'.

In some situations it may be advantageous to include multiple vacuum suction heads 162, 162' one after another in terms of achieving an efficient removal of non-bonded natural fibers from the bonded air-laid blank 10. In such a case, the upstream vacuum suction head 162 could be arranged to provide a rough removal of non-bonded natural fibers, thereby removing the majority of such non-bonded natural fibers from the main surface(s) 12 of the bonded air-laid blank 10. The downstream vacuum suction head 162' would then remove any remaining non-bonded natural fibers, which were not successfully removed by the upstream vacuum suction head 162.

The suction action, i.e., the vacuum or negative pressure, exerted by the multiple suction heads 162, 162' could be substantially the same. In another embodiment, different such suction actions, i.e., vacuum or negative pressures, are exerted by the upstream and downstream suction heads 162, 162'. For instance, the upstream vacuum suction head 162 could provide a larger vacuum or negative pressure than the downstream vacuum suction head 162' to remove most of the non-bonded natural fibers including the larger non-bonded natural fibers. The comparatively lower vacuum or negative pressure of the downstream vacuum suction head 162' would then allow removal of remaining non-bonded natural fibers including smaller fiber particles and debris from the main surface 12 of the bonded air-laid blank 10.

The discussion above and in connection with Fig. 14 applies regardless of whether the multiple vacuum suction heads 162, 162' are arranged as shown in Fig. 14 to remove non-bonded natural fibers from the first or upper main surface 12 of the bonded air-laid blank 10, or arranged to remove non-bonded natural fibers from the second or lower main surface 14 of the bonded air-laid blank 10, or indeed having a first set of multiple vacuum suction heads 162, 162' arranged to remove non-bonded natural fibers from the first or upper main surface 12 of the bonded air-laid blank 10 and a second set of multiple vacuum suction heads 164 arranged to remove non-bonded natural fibers from the second or lower main surface 14 of the bonded air-laid blank 10.

If the inline vacuum suction system 160 comprises first and section vacuum suction heads 162, 164 arranged for removing non-bonded natural fibers from both the main surfaces 12, 14 of the bonded airlaid blank 10, then the first vacuum suction head 162 and the second vacuum suction head 164 are preferably aligned along an axis 15 perpendicular to the first and second main surfaces 12, 14 of the bonded air-laid blank 10 as shown in Fig. 12. This means that aligned portions of both main surfaces 12, 14 are preferably cleaned by the aligned vacuum suction heads 162, 164. As a consequence of such an alignment, vacuum suction will be applied onto opposite and aligned portions of the main surfaces 12, 14 of the bonded air-laid blank 10. Such an approach reduces the risk of the portion of the bonded air-laid blank 10 beneath the vacuum suction head 162 or above the vacuum suction head 164 sightly bulging towards the vacuum suction head 162, 164 due to the applied vacuum or suction pressure. Hence, applying such vacuum or suction pressures on either side of the bonded air-laid blank 10 preferably simultaneously and preferably substantially aligned along the axis 15 as shown in Fig. 12 prevents or at least restricts the bonded air-laid blank 10 from bulging towards a vacuum suction head 162, 164.

The axis 15 as shown in Fig. 12 is perpendicular to the main surfaces 12, 14 of the bonded air-laid blank 10 when positioned on the air-permeable conveyor 120 or the downstream conveyor 180. This means that the axis 15 is also perpendicular to the conveyor belt 122, 182 of the air-permeable conveyor 120 or the downstream conveyor 180. Hence, the axis 15 is substantially parallel to the normal of the main surfaces 12, 14 of the bonded air-laid blank 10 when positioned on the air-permeable conveyor 120 or the downstream conveyor 180. In a typical example, the axis 15 is a vertical axis 15.

The alignment of the first and second vacuum suction heads 162, 164 along the axis 15 is a preferred arrangement if the inline vacuum suction system 160 comprises vacuum suction heads 162, 164 arranged to remove non-bonded fibers from both main surfaces 12, 14 of the bonded air-laid blank 10. The embodiments are, however, not limited thereto. Hence, the first and second vacuum suction heads 162, 164 need not necessarily be aligned but could be displaced relative each other so that one of the first and second vacuum suction heads 162, 164 is arranged closer to the forming head 110 as compared to the other of the first and second vacuum suction heads 162, 164. In such a case, the first vacuum suction head 162 could be arranged upstream of the second vacuum suction head 164 or the second vacuum suction head 164 is arranged upstream of the first vacuum suction head 162. The at least one vacuum suction head 162, 164 is preferably perpendicularly angled relative to the main surface 12, 14 of the bonded air-laid blank 10. The embodiments are, however, not limited thereto. The at least one vacuum suction head 162, 164 could alternatively be angled with an angle larger than 0° but smaller than 90° relative to the main surface 12, 14 of the bonded air-laid blank 10. Such a situation corresponds to having a non-zero angle between the axis 15 and the at least one vacuum suction head 162, 164.

In an embodiment, air turbulence is created during removal of non-bonded natural fibers. Such an embodiment is shown in Fig. 8. The method then continues from step S3 in Fig. 2. A next step S60 comprises creating air turbulence in connection with a portion of the at least one main surface 12, 14 of the bonded air-laid blank 10 in vicinity of the at least one vacuum suction head 162, 164. The creation of the air turbulence in step S60 is preferably performed in parallel with and during removal of non-bonded natural fibers in step S4 in Fig. 2. The air turbulence can be created according to embodiments discussed further below in connection with Figs. 15-16. Briefly, distance elements 30, 40 can be arranged upstream and downstream of a vacuum suction nozzle 161 , 163 of the at least one vacuum suction head 162, 164. Such distance elements 30, 40 may then comprise openings 35, 45, through which air will be sucked as the at least vacuum suction head 162, 164 is operating. This inflow of air creates a turbulence in connection with the portion of the at least one main surface 12, 14 of the bonded air-laid blank 10 in vicinity of the at least one vacuum suction head 162, 164.

Such a turbulence facilitates removal of the non-bonded natural fibers from the bonded air-laid blank 10. Thus, the turbulence reduces the vacuum or suction pressure needed by the at least one vacuum suction head 162, 164 to suck up non-bonded natural fibers from the bonded air-laid blank 10. The turbulence additionally helps in detaching fibers that are insufficiently bonded in the bonded air-laid blank 10, in particular present at or close to the main surface(s) 12, 14 of the bonded air-laid blank 10.

The air turbulence created in step S60 of Fig. 8 in connection with a portion of the at least one main surface 12, 14 of the bonded air-laid blank 10 in vicinity of the at least one vacuum suction head 162, 164 is a turbulence of air induced by the vacuum or suction pressure applied by the at least one vacuum suction head 162, 164. Hence, there is no need for the application of any gas, air or water jet that is sprayed into the bonded air-laid blank 10 in order to achieve the air turbulence. This is a significant advantage of the method and system 100 of the present invention as application of such gas, air or water jets into the bonded air-laid blank 10 requires the arrangement of additional equipment in the system 100. Furthermore, such gas, air or water jets may negatively affect the porous, open cell structure of the bonded air-laid blank 10. Water jets further would mean that the bonded air-laid blank 10 needs to be exposed to an additional drying operation in order to remove any moisture introduced into the bonded air-laid blank 10 by such water jets.

In an embodiment, the method comprises an additional step S20 as shown in Fig. 4. In such an embodiment, the method continues from step S3 to step S20. This step S20 comprises transporting the bonded air-laid blank 10 past the inline vacuum suction system 160 comprising the at least one vacuum suction head 162, 164. The transport of the bonded air-laid blank 10 in step S20 is preferably performed in parallel with and during removal of non-bonded natural fibers in step S4 in Fig. 2.

The transport of the bonded air-laid blank 10 past the vacuum suction head(s) 162, 164 of the inline vacuum system 160 is preferably performed by the air-permeable conveyor 120 or a downstream conveyor 180. For instance, as shown in Figs. 9, 11, 13-14, the air-permeable conveyor 120 could be used to first capture the natural fibers and the polymer binder as an unbonded air-laid web 20 in connection with the outlet 113 of the forming head 110. The air-permeable conveyor 120 then transports the unbonded air-laid web 20 past the heating device 140 to heat the unbonded air-laid web 20 to at least partly melt the polymer binder and bind the natural fibers to form the bonded air-laid blank 10. The bonded air-laid blank 10 is then further transported by the air-permeable conveyor 120 to and past the inline vacuum suction system 160 and its vacuum suction head(s) 162, 164.

Fig. 12 illustrates another embodiment of the system 100 comprising a downstream conveyor 180 in addition to the air-permeable conveyor 120. In such an embodiment, the inline vacuum suction system 160 is preferably arranged between the air-permeable conveyor 120 and the downstream conveyor 180. The bonded air-laid blank 10 is then transported up to the inline vacuum suction system 160 by the air- permeable conveyor 120 and then past the inline vacuum suction system 160 by the air-permeable conveyor 120 and the downstream conveyor 180. Fig. 10 illustrates another embodiment of the system 100 comprising the air-permeable conveyor 120 and a downstream conveyor 180. In this embodiment, the air-permeable conveyor 120 transports the unbonded air-laid web 20 passed the heating device 140, a cooling device 150 and to a cutting device 170. The cut bonded air-laid blank 10 is then transported from the cutting device 170 to the inline vacuum suction system 160 by the downstream conveyor 180.

Fig. 5 is a flow chart illustrating another optional step of the method in Fig. 2 according to an embodiment. In this embodiment, the method continues from step S3 in Fig. 2. A next step S30 comprises moving the at least one vacuum suction head 162, 164 relative the bonded air-laid blank 10. The method then continues to step S4 in Fig. 2. Alternatively, this step S30 can be performed at least partly in parallel with step S4 in Fig. 2. The movement of the at least one vacuum suction head 162, 164 in step S30 is preferably along the longitudinal extension of the bonded air-laid blank 10 as indicated by the hatched arrows in Fig. 11 and/or in a traverse direction, i.e., perpendicular to the direction indicated by the hatched arrows. Fig. 11 schematically illustrates an embodiment of implementing such a process. In this embodiment, the system 100 comprises a transport system 166 arranged to move the vacuum suction head 162. The transport system 166 could, for instance, include a stationary frame or guide 167, to which the vacuum suction head 162 is connected by a movable support 168. The movable support 168 and the vacuum suction head 162 are then movable along the stationary frame or guide 167 as indicated by the hatched arrows in Fig. 11. This means that the vacuum suction head 162 can be moved relative the bonded air-laid blank 10 to remove non-bonded natural fibers therefrom.

In Fig. 11, the transport system 166 is disclosed as allowing a movement of the vacuum suction head 162 along the transport direction of the bonded air-laid blank 10 and thereby along the main longitudinal direction of the air-permeable conveyor 120. This corresponds to a movement of the vacuum suction head 162 along the length L, see Fig. 1A, of the bonded air-laid blank 10. In another embodiment, the transport system 166 is arranged to move the vacuum suction head 162 along a transverse direction substantially perpendicular to the movement as shown in Fig. 11 . In such an embodiment, the movement of the vacuum suction head 162 is substantially along the width W, see Fig. 1A, of the bonded air-laid blank 10. In a further embodiment, the transport system 166 could enable movement of the vacuum suction head 162 both along the longitudinal direction and along the transverse direction. For instance, the vacuum suction head 162 could be attached to and supported by a robot arm freely moveable over the main surface 12 of the bonded air-laid blank 10.

The embodiments described above in connection with Figs. 4 and 5 could be combined. In such a case, the bonded air-laid blank 10 is transported past the inline vacuum suction system 160 by the air- permeable conveyor 120 and/or the downstream conveyor 180 while the transport system 166 moves the at least one vacuum suction head 162 relative the bonded air-laid blank 10. As an example, the transport system 166 could move the vacuum suction head 162 along the transverse direction, such as from one longitudinal side 11 of the bonded air-laid blank 10 towards the opposite longitudinal side 11 , while the bonded air-laid blank 10 is transported by the air-permeable conveyor 120 and/or the downstream conveyor 180 along the longitudinal direction. Fig. 6 is a flow chart illustrating an additional, optional step of the method shown in Fig. 2. In this embodiment, the method continues from step S3. A next step S40 comprises cooling the bonded air-laid blank 10 by blowing a gas or gas mixture through the bonded air-laid blank 10. The method then continues to step S4 in Fig. 2.

In this embodiment, the system 100 comprises a cooling device 150 arranged downstream of the heating device 140 but upstream of the inline vacuum suction system 160. Such a cooling device 150 is then arranged to blow a gas or a gas mixture, typically air, through the bonded air-laid blank 10 to cool the bonded air-laid blank 10 as output from the heating device 140. The cooling device 150 could then cool the air-laid blank 10 to a temperature at or slightly above ambient temperature or to a temperature above ambient temperature but below the temperature inside the heating device 140, such as to a temperature at which the polymer binder solidifies sufficiently.

In an embodiment, the method also comprises cutting, in step S50 as shown in Fig. 7, the bonded airlaid blank 10 prior to and/or after removing the non-bonded natural fibers. Thus, this cutting operation in step S50 could be performed following heating in step S3 of Fig. 2 or, if cooling is applied in step S40, following step S40 and thereby prior to removing the non-bonded natural fibers in step S4. Alternatively, the cutting in step S50 could be performed after removing non-bonded natural fibers in step S4 in Fig. 2.

The cutting operation in step S50 could be performed using any suitable cutter or cutting device 170. Illustrative, but non-limiting examples, of such cutting device 170 include a saw, a punch, a knife, etc.

The cutting in step S50 divides the (continuous) bonded air-laid blank 10 into suitable sizes for downstream handling and processing. The cutting could be across the width of the bonded air-laid blank 10 to get, for instance, rectangular or quadratic bonded air-laid blank pieces.

The cutting in step S50 is preferably performed while the bonded air-laid blank 10 is transported in the production line. Hence, it is generally preferred if the cutting device 170 is moved in synchrony with the bonded air-laid blank 10 during the cutting in step S50. For instance, the cutting device 170 is starting the cutting in step S50 from a start position and then moves in synchrony with the bonded air-laid blank 10 in the longitudinal direction of the bonded air-laid blank 10 until the cutting is completed at a stop position. The cutting device 170 is then preferably transported back to the start position to be ready for a next cutting operation. As shown in Figs. 9, 11-14, 19-20 the air-permeable conveyor 120 (Figs. 9, 11 , 13-14) or the downstream conveyor 180 (Figs. 12, 19-20) could include bend rollers 121 , 181 and one take-up roller 123, 183 (Figs. 9, 1 1-13, 19-20) or multiple, typically two, take-up rollers 123 (Fig. 14) arranged to divert the air- permeable conveyor belt 122 or conveyor belt 182 away from the cutting device 170. This means that the conveyor belt 122, 182 turns away from the cutting device 170 to enable the cutting device 170 to cut through the complete thickness of the bonded air-laid blank 10 without the risk of engaging and damaging the conveyor belt 122, 182. The bend rollers 121 , 181 could be in the form of bend pulleys or bend idlers and the take-up roller(s) 123, 183 could be in the form of take-up pulley (s) or take-up idler(s).

In an embodiment, the cutting device 170 and the bend rollers 121 , 181 and take-up roller(s) 123, 183 are preferably movable relative to the conveyor(s) 120, 180 to be moved, preferably in synchrony, with the bonded air-laid blank 10 transported by the conveyor(s) 120, 180. This is schematically illustrated by the hatched arrow in Figs. 9, 11-14, 19-20.

Fig. 10 illustrates another solution in which the air-permeable conveyor 120 ends upstream of the cutting device 170 and the downstream conveyor 180 starts downstream of the cutting device 170. This means that there will be a gap between the opposite driver rollers 126, 184 and thereby of the two conveyors 120, 180 as shown in the figure. The cutting device 170 can then cut through the complete thickness of the bonded air-laid blank 10 without cutting into or even through the conveyor belts 122, 182.

The embodiment as shown in Fig. 10 is sometimes less preferred as compared to the embodiment of the cutting device 170 with diversion of the air-permeable conveyor belt 122 or conveyor belt 182 away from the cutting device 170 since it will typically not support cutting of the bonded air-laid blank 10 while the bonded air-laid blank 10 is transported. In such a case, the transport of the bonded air-laid blank 10 may optionally be temporarily stopped or at least slowed down to allow the cutting device 170 to cut the bonded air-laid blank 10 and then the air-permeable conveyor 120 could be started again or speeded up to the preferred transport speed.

In an embodiment, a vacuum suction head 169, see Figs. 9 and 10, may be arranged in connection with the cutting device 170 to remove any particles or fibers that may come loose or detach from the bonded air-laid blank 10 during the cutting operation in step S50 of Fig. 7. Such a vacuum suction head 169 could be arranged adjacent the cutting device 170, such as upstream or downstream of the cutting device 170, or indeed having a first or upstream vacuum suction head arranged upstream of the cutting device 170 and a second or downstream vacuum suction head arranged downstream of the cutting device 170. The one or more vacuum suction heads 169 arranged in connection with the cutting device 170 could be of the same type or different type as compared to the at least one vacuum suction head 162, 164 arranged to remove non-bonded natural fibers in step S4 of Fig. 2.

The vacuum suction head(s) 169 arranged in connection with the cutting device 170 is arranged to remove particles or fibers that detach from the bonded air-laid blank 10 during cutting, i.e., mainly from the cut surfaces. The vacuum suction head(s) 169 is(are) typically moved together with the cutting device 170 during the cutting operation. This is in clear contrast to the at least one vacuum suction head 162, 164 of the invention arranged to remove non-bonded natural fibers from the at least one main surface 12, 14 of the bonded air-laid blank 10. Furthermore, the at least one vacuum suction head 162, 164 of the invention is(are) not moved together with the cutting device 170 during the cutting operation. The at least one vacuum suction head 162, 164 of the invention is arranged upstream of or downstream of the cutting device 170 but typically not in connection with the cutting device 170 as the vacuum suction head(s) 169.

Another aspect of the invention relates to a system 100 for producing a bonded air-laid blank 10, see Figs. 9-14. The system 100 comprises a forming head 110 comprising at least one inlet 111 configured to receive natural fibers and a polymer binder. The forming head 110 also comprises an outlet 113. The system 100 also comprises an air-permeable conveyor 120 arranged in connection with the outlet 113 to capture the natural fibers and the polymer binder as an unbonded air-laid web 20. The system 100 further comprises a heating device 140 arranged to heat the unbonded air-laid web 20 to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank 10. An inline vacuum suction system 160 is comprised in the system 100 and comprises at least one vacuum suction head 162, 164 arranged to remove non-bonded natural fiber from at least one main surface 12, 14 of the bonded air-laid blank 10.

Fig. 9 illustrates an embodiment of the system 100. In this embodiment, the forming head 110 comprises an inlet 111 arranged in connection with its upper end 112 of the forming head 110 to receive a mixture of the natural fibers and the polymer binder. As discussed in the foregoing, the embodiment is not limited thereto. In clear contrast, multiple such inlets 111 could be arranged from the upper end 112 towards the bottom end 114 of the forming head 110 to receive the mixture of the natural fibers and the polymer binder or indeed at least one such inlet 111 for the natural fibers and at least one inlet 11 1 for the polymer binder. The outlet 113 of the forming head 110 is typically arranged in connection with the lower end 114 of the forming head 110 and in vicinity of the air-permeable conveyor 120. This means that the natural fibers and polymer binder passing through the forming head 110 are captured as an unbonded air-laid web 20 on the air-permeable conveyor 120.

In an embodiment, the system 100 comprises a vacuum source 130 arranged beneath the air-permeable conveyor 120 to provide a gas suction through the air-permeable conveyor 120 in connection with the outlet 113 of the forming head 110. In such a case, the vacuum source 130 is arranged to draw the natural fibers and polymer binder onto the air-permeable conveyor 120 to deposit them thereon and at least partly compact them forming the unbonded air-laid web 20.

The vacuum source 130 is arranged to apply a vacuum or gas suction over the air-permeable conveyor 120 and, thus, draws the natural fibers and the polymer binder down onto the air-permeable conveyor 120.

The air-permeable conveyor 120 could be any type of conveyor 120, over which a vacuum or gas suction can be applied by the vacuum source 130 and onto which the natural fibers and polymer binder can be captured to form the unbonded air-laid web 20. Typical examples of such air-permeable conveyors 120 that could be used include belt conveyors, in which the belt comprises a plurality of openings, through holes or channels for allowing air to be sucked or drawn through the belt, wire conveyors and mesh conveyors with meshes that are small enough to allow capturing of the natural fibers and polymer binder. In such a case, the belt, wire network or mesh is preferably an endless or jointless belt, wire network or mesh running between drive rollers 124, 126, also referred to as tail pulley 124 and head pulley 126.

The captured air-laid web 20 is then transported by the air-permeable conveyor 120 towards the heating device 140. The heating device 140 may, for instance, be in the form of a bonding oven. The heating device 140 is arranged to provide heat, such as in the form of hot air that is circulated through the unbonded air-laid web 20 to melt or partly melt the polymer binder. The polymer binder thereby becomes tacky and adheres to the natural fibers and, thus, holds the fiber material together and thereby results in the bonded air-laid blank 10.

In a particular embodiment, the heating device 140 is arranged to heat the unbonded air-laid web 20 to a temperature selected within an interval of from 100°C up to 210°C, preferably within an interval of from 100°C up to 190°C, and more preferably within an interval of from 100°C up to 165°C. A too high temperature may damage and deteriorate the natural fibers in the unbonded air-laid web 20.

The heating device 140 may also be arranged to densify the air-laid web 20 to create a larger number of binding points in the fiber structure and, thus, a stronger and denser bonded air-laid blank 10. The heating device 140 could perform such a densification by applying the heat and simultaneously applying pressure onto the unbonded air-laid web 20 to form the air-laid blank 10.

Alternatively, a separate compression device, such as calender, (not shown) could be arranged downstream of the heating device 140 to perform the densification on the bonded air-laid blank 10 before it has been allowed to cool after the heating device 140.

The densification performed by the heating device 140 or the separate compression device can include various types of operations including, but not limited to, calendering and/or pressing operations.

In an embodiment, the system 100 may comprise a cooling device 150 arranged to cool the bonded airlaid blank 10 by blowing gas or a gas mixture through the bonded air-laid blank 10. The cooling device 150 is, thus, arranged downstream of the heating device 140 and the optional bonding device. The cooling device 150 may then blow gas, such as air, through the bonded air-laid blank 10 to reduce the temperature thereof before reaching the inline vacuum suction system 160. The bonded air-laid blank 10 leaving the cooling device 150 preferably has a temperature close to or slightly above ambient temperature, such as room temperature (20-25°C), or at least a temperature below the preferred heating temperature inside the heating device 140, preferably below the softening temperature of the polymer binder.

In the embodiment shown in Fig. 9, the inline vacuum suction system 160 comprises a single vacuum suction head 162 arranged to remove non-bonded natural fibers from the upper main surface 12 of the bonded air-laid blank 10.

In this embodiment, the vacuum suction head 162 is arranged to remove non-bonded natural fibers from a first main surface 12 of the bonded air-laid blank 10, also referred to as upper main surface, positioned with a second, opposite main surface 14 of the bonded air-laid blank 10, also referred to as lower main surface, on the air-permeable conveyor 120, see Fig. 9, or a downstream conveyor 180, see Fig. 10. In an embodiment, the inline vacuum suction system 160 also comprises a controller 165 connected to and arranged to control operation of the vacuum suction head(s) 162 of the inline vacuum suction system 160. The controller 165 could, for instance, control when the vacuum suction head(s) 162 is(are) on or off and optionally also control the vacuum or suction pressure applied by the vacuum suction head(s) 162.

A cutting device 170 is, in this embodiment, arranged downstream of the inline vacuum suction system 160 to cut the bonded air-laid blank 10 after removal of non-bonded fibers from the main surface 12. As mentioned in the foregoing, the cutting device 170 could be any type of cutter that is capable of cutting air-laid blanks. Illustrative, but non-limiting examples, of such cutting devices 170 include a saw, a punch, a knife, etc.

Fig. 10 illustrates another embodiment of the system 100, in which the cutting device 170 is arranged upstream of the inline vacuum suction system 160. In such a case, the inline vacuum suction system 160 is arranged to remove non-bonded natural fibers from the cut bonded air-laid blanks 10. The air- permeable conveyor 120 of the system 100 as shown in Fig. 10 ends upstream of but in the vicinity of the cutting device 170. A downstream conveyor 180 comprising a conveyor belt 182 running between drive rollers 184, 186 (tail pulley 184 and head pulley 186) starts downstream of but in the vicinity of the cutting device 170. The bonded air-laid blank 10 is then transported by the air-permeable conveyor 120 to the cutting device 170 where it is cut. The cut bonded air-laid blank 10 is then transported by the downstream conveyor 180 to and past the inline vacuum suction system 160.

Fig. 11 illustrates an embodiment of the system 100 similar to the one in Fig. 9 but with a transport system 166 arranged to move the at least one vacuum suction head 162 relative the bonded air-laid blank 10.

In an embodiment, the transport system 166 comprises a stationary frame or guide 167, along which a movable support 168 is movable as indicated by the hatched arrows. This movable support 168 is connected to and supports at least one vacuum suction head 162 to transport the at least one vacuum suction head 162 along the stationary frame or guide 167 and relative a main surface 12 of the bonded air-laid blank 10.

The transport system 166 typically comprises a motor (not shown) configured to move the movable support 168 and the at least one vacuum suction head 162. The movement of the movable support 168 and the at least one vacuum suction head 162 could be along the longitudinal direction of the bonded airlaid blank 10 as indicated in Fig. 11 and/or along the transverse direction of the bonded air-laid blank 10.

The embodiments are not limited to the particular transport system 166 as shown in Fig. 11 but can be used with any such transport system 166 that is capable of moving the at least one vacuum suction head 162 relative the bonded air-laid blank 10, such as along the longitudinal extension of the bonded air-laid blank 10, i.e., along the length L, and/or in a transverse direction, i.e., along the width W in Fig. 1A. An example of another type of transport system 166 is to have a movable robot arm, to which the at least one vacuum suction head 162 is attached.

The controller 165 illustrated in Fig. 9 could be arranged to control the movement of the at least one vacuum suction head 162 by the transport system 166 in Fig. 11.

Fig. 12 illustrates an embodiment of the system 100, in which the inline vacuum suction system 160 comprises a first vacuum suction head 162 and a second vacuum suction head 164. The first vacuum suction head 162 is then arranged to remove non-bonded natural fibers from a first main surface 12 of the bonded air-laid blank 10 and the second vacuum suction head 164 is arranged to remove non-bonded natural fibers from a second, opposite main surface 14 of the bonded air-laid blank 10.

In an embodiment, the first vacuum suction head 162 and the second vacuum suction head 164 are aligned along a vertical axis 15 as shown in Fig. 12. Such an embodiment provides oppositely directed vacuum or suction pressures by the two vacuum suction heads 162, 164, which, when applied simultaneously, reduce the risk of the bonded air-laid blank 10 bulging towards any of the vacuum suction heads 162, 164.

In an embodiment, the system 100 comprises a downstream conveyor 180 configured to transport the bonded air-laid blank 10 from the inline vacuum suction system 160. In such an embodiment, the second vacuum suction head 164 is arranged at a position in between the air-permeable conveyor 120 and the downstream conveyor 180.

The downstream conveyor 180 does not need to be air-permeable. Furthermore, the downstream conveyor 180 is arranged to transport the bonded air-laid blank 10 rather than capturing the natural fibers and polymer fibers. This means that also other conveyor solutions than belt, wire or mesh conveyors are available for the downstream conveyor 180 including, but not limited to, roller conveyors. In Fig. 12, the downstream conveyor 180 has been exemplified by a belt conveyor 180 with an endless or jointless belt 182 running between drive rollers 184, 186.

Fig. 13 illustrates another embodiment of the system 100 comprising an upper conveyor 220, preferably an upper air-permeable conveyor 220 arranged above the unbonded air-laid web 20 and the bonded airlaid blank 10. Thus, in this embodiment the system 100 is arranged to sandwich the unbonded air-laid web 20 and at least a portion of the bonded air-laid blank 10 between the air-permeable conveyor 120 and the upper air-permeable conveyor 220. Such an upper air-permeable conveyor 220 is advantageous if the heating device 140 is arranged to blow hot air through the unbonded air-laid web 20 from multiple directions, such as from above and from below. The opposite air-permeable conveyors 120, 220 thereby prevent or at least restrict natural fibers from blowing away from the unbonded air-laid web 20 when blowing hot air into the unbonded air-laid web 20.

In Fig. 13, the upper air-permeable conveyor 220 starts downstream of the forming head 110 and ends upstream of the inline vacuum suction system 160. The embodiments are, however, not limited thereto. It is generally preferred if the upper air-permeable conveyor 220 is at least arranged to extend over the unbonded air-laid web 20 in connection with the heating device 140. It is generally preferred if the upper air-permeable conveyor 220 also extends past the cooling device 150 to reduce the risk of blowing away natural fibers before they have become bonded to each other due to cooling of the polymer binder below its softening temperature. The upper air-permeable conveyor 220 may, though, provide positive effects also in connection with the inline vacuum suction system 160 by restricting the bonded air-laid blank 10 from moving towards the at least one vacuum suction head 162 when applying a vacuum suction, which will be further described in connection with Figs. 17 and 18. The upper air-permeable conveyor 220 could, for instance, be in the form of an air-permeable belt 222 running between drive rollers 224, 226.

Fig. 14 illustrates another embodiment of the system 100, in which the inline vacuum suction system 160 comprises multiple vacuum suction heads 162, 162' arranged one after another above the bonded airlaid blank 10, i.e., an upstream vacuum suction head 162 and a downstream vacuum suction head 162'. Such a solution could achieve a more efficient removal of non-bonded natural fibers from the bonded airlaid blank 10 as compared to merely using a single vacuum suction head. As discussed in the foregoing, the multiple vacuum suction heads 162, 162' could then be arranged or controlled, by the controller 165 in Fig. 9, to provide different vacuum or suction pressures. It is also possible to have at least one intermediate vacuum suction head arranged between the upstream vacuum suction head 162 and the downstream vacuum suction head 162' if more than two such vacuum suction heads 162, 162' are needed.

Fig. 19 illustrates another embodiment of the system 100 comprising the air-permeable conveyor 120 arranged in connection with the outlet 113 to capture the natural fibers and the polymer binder as an unbonded air-laid web 20 and a downstream conveyor 180. In this embodiment, the air-permeable conveyor 120 ends shortly upstream of or in connection with the heating device 140, whereas the downstream conveyor 180 starts shortly upstream of or in connection with the heating device 140. In such an embodiment, the unbonded air-laid web 20 will be carried by the downstream conveyor 180 through the heating device 140.

The downstream conveyor 180 comprises a conveyor belt 182 running between drive rollers 184, 186 (tail pulley 184 and head pulley 186). The conveyor belt is preferably air-permeable to allow for an efficient heating of the unbonded air-laid web 20 in the heating device 140, such as by circulating hot air within the heating device 140.

Fig. 20 illustrates a further embodiment of the system 100 comprising the air-permeable conveyor 120, the downstream conveyor 180 and an intermediate conveyor 190. In this embodiment, the air-permeable conveyor 120 ends shortly upstream of or in connection with the heating device 140, whereas the intermediate conveyor 190 starts shortly upstream of or in connection with the heating device 140 and ends at a position between the heating device 140 and the cooling device 150. The downstream conveyor 180 therefore starts at a position between the heating device 140 and the cooling device 150. In the embodiment shown in Fig. 20, the air-permeable conveyor 120, the intermediate conveyor 190 and the downstream conveyor 180 are shown as having conveyor belts 122, 192, 182 running between drive rollers 124, 126, 194, 196, 184, 186. The conveyor belts 192, 182 of the intermediate and downstream conveyors 190, 180 may be air-permeable as the air-permeable belt 122 in particular to support circulation of hot air in the heating device 140 and circulation of cool air in the cooling device 150.

The various embodiments discussed above and shown in Figs. 9-14, 19-20 could be combined. For instance, the controller as shown in Fig. 9 could be arranged as part of the inline vacuum suction system 160 in any of the embodiments shown in Figs. 10-14, 19-20. The cutting device 170 could be arranged upstream of the inline vacuum suction system 160 in any of the systems 100 as shown in Figs. 9, 11-14, 19-20. The inline vacuum suction system 160 in any of the embodiments shown in Figs. 9-10, 12-14, 19- 20 could comprise a transport system 166, such as shown in Fig. 11. In the embodiment shown in Fig. 12, the transport system 166 could be arranged to move the upper vacuum suction head 162, move the lower vacuum suction head 164, or move both the upper vacuum suction head 162 and the lower vacuum suction head 164, either together or independently. The transport system 166 could, if arranged in the system 100 as shown in Fig. 14, be arranged to move the upstream vacuum suction head 162, move the downstream vacuum suction head 162', or move both the upstream and downstream vacuum suction heads 162, 162', either together or independently.

The embodiments shown in Figs. 9, 11 , 13-14 could comprise the air-permeable conveyor 120 and a downstream conveyor 180 as shown in Figs. 10, 12 or 19. Furthermore, the embodiments shown in Figs. 9-14, 19 could comprise the air-permeable conveyor 120, the intermediate conveyor 190 and the downstream conveyor 180 as shown in Fig. 20. Either of the solutions presented in Figs. 9, 11 -14, 19-20 or Fig. 10 could be used in any of the embodiments to prevent the cutting device 170 from cutting into the air-permeable conveyor 120.

Furthermore, the usage of two or more vacuum suction heads 162, 162' arranged one after the other as shown for the system 100 in Fig. 14 could be applied to any of the systems 100 shown in Figs. 9-13, 19- 20. In the embodiment shown in Fig. 12, the system 100 could comprise upstream and downstream upper vacuum suction heads 162 and a single lower vacuum suction head 164, upstream and downstream lower vacuum suction heads 164 and a single upper vacuum suction head 162, or upstream and downstream upper vacuum suction heads 162 and upstream and downstream lower vacuum suction heads 164.

In Figs. 9-11 and 13-14, 19-20 the one or more vacuum suction heads 162, 162' is or are arranged above the bonded air-laid blank 10 to remove non-bonded natural fibers from the upper main surface 12 of the bonded air-laid blank 10. In other embodiments, the one or more vacuum suction heads is or are instead arranged below the bonded air-laid blank 10 to remove non-bonded natural fibers from the lower main surface 14 of the bonded air-laid blank 10.

Figs. 15 and 16 schematically illustrate a close up of one embodiment of the inline vacuum suction system 160 of Fig. 12 comprising a first or upper vacuum suction head 162 and a second or lower vacuum suction head 164. The at least one vacuum suction head 162, 162' of the system 100 shown in Figs. 9-11 , 13- 14 could be designed according to the vacuum suction heads 162, 164 shown in Figs. 15-16. In an embodiment, the at least one vacuum suction head 162, 164 comprises an upstream distance element 30 comprising a lip 34 having a planar surface configured to abut or contact one of the at least one main surfaces 12, 14 of the bonded air-laid blank 10 and a wall 36 attached to the lip 34 and comprising multiple openings 35. The at least one vacuum suction head 162, 164 also comprises, in this embodiment, a downstream distance element 40 comprising a lip 44 having a planar surface configured to abut or contact one of the at least one main surfaces 12, 14 of the bonded air-laid blank 10 and a wall 46 attached to the lip 44 and comprising multiple openings 45. The at least one vacuum suction head 162, 164 then comprises a vacuum suction nozzle 161 , 163 arranged between the upstream distance element 30 and the downstream distance element 40 with the walls 36, 46 of the upstream distance element 30 and the downstream distance element 40 attached directly or indirectly to the vacuum suction nozzle 161 , 163.

The distance elements 30, 40 are then arranged with the lips 34, 44 in contact with or abutting the upper or lower main surfaces 12, 14 of the bonded air-laid blank 10. The lips 34, 36 thereby prevent or at least significantly restrict the main surface 12, 14 of the bonded air-laid blank 10 to move or bulge towards the vacuum suction nozzle 161 , 163 when applying the vacuum or suction pressure. Thus, the distance elements 30, 40 prevent the bonded air-laid blank 10 from contacting the vacuum suction nozzle 161 , 163 and thereby block or close the entrance of the vacuum suction nozzle 161 , 163, which would prevent removal of non-bonded natural fibers from the main surface(s) 12, 14 of the bonded air-laid blank 10. Furthermore, a bonded air-laid blank 10 bulging in contact with the vacuum suction nozzle 161 , 163 may become damaged by the vacuum suction nozzle 161 , 163 penetrating into the bonded air-laid blank 10. This would also mean that the bonded air-laid blank 10 could become stuck to the vacuum suction nozzle 161 , 163 causing a stop in the production process.

In addition to the distance elements 30, 40, the system 100 may comprise upper conveyors 220, 280 arranged to be positioned above the bonded air-laid blank 10, i.e., in contact with or with a small distance from the upper main surface 12 of the bonded air-laid blank 10 as shown in Fig. 17. The upper conveyors 220, 280 thereby restrict the bonded air-laid blank 10 from bulging upwards towards the first vacuum suction head 162 and its vacuum suction nozzle 161 , whereas the air-permeable conveyor 120 and the downstream conveyor 180 restrict the bonded air-laid blank 10 from bulging downwards towards the second vacuum suction head 164 and its vacuum suction nozzle 163. The upper conveyors 220, 280 could be belt conveyors 220, 280 having a respective belt 222, 282 running between drive rollers 226, 284. In an embodiment, the upper conveyors 220, 280 comprise an upper upstream conveyor 220 arranged upstream of the first vacuum suction head 162 and an upper downstream conveyor 280 arranged downstream of the first vacuum suction head 162. As discussed in the foregoing in connection with Fig. 13, the upper upstream conveyor 220 is preferably an upper upstream air-permeable conveyor 220 if the upper upstream conveyor 220 extends also past the heating device 140. The upper downstream conveyor 280 does not need to be air-permeable and could thereby contain a traditional belt 282 rather than an air-permeable belt.

Fig. 18 illustrates another embodiment with rollers 206, 204 arranged to restrict the bonded air-laid blank 10 from becoming stuck to the vacuum suction nozzle 161 of the first vacuum suction head 162 during use. For instance, an upstream roller 206 could be arranged upstream but in vicinity to the first vacuum suction head 162 and arranged to be in contact with or at a small distance above the upper main surface 12 of the bonded air-laid blank 10 and a downstream roller 204 arranged downstream but in vicinity to the first vacuum suction head 162 and arranged to be in contact with or at a small distance above the upper main surface 12 of the bonded air-laid blank 10.

In an embodiment, an entrance or opening of the vacuum suction nozzle 161 , 163 is arranged to be positioned at a distance from the at least one main surface 12, 14 of the bonded air-laid blank 10. In a preferred embodiment, the distance is selected within an interval of from 1 to 10 mm, preferably within an interval of from 1 to 5 mm. Such a distance achieves an efficient removal of non-bonded natural fibers but also reduces the risk of the bonded air-laid blank 10 becoming stuck on the vacuum suction nozzle

161. 163 and blocking the entrance of the vacuum suction nozzle 161 , 163.

In an embodiment, the controller 165 as shown in Fig. 9 could be configured to adjust a distance between the at least one surface 12, 14 of the bonded air-laid blank 10 and the vacuum suction nozzle 161 , 163 of the at least one vacuum suction head 162, 164. Hence, in this embodiment, the distance between the entrance or opening of the vacuum suction nozzle 161, 163 and the bonded air-laid blank 10 can be adjusted by the controller 165. In another embodiment, the distance between the at least one surface 12, 14 of the bonded air-laid blank 10 and the vacuum suction nozzle 161 , 163 of the at least one vacuum suction head 162, 164 could be manually adjusted. In such a case, the at least one vacuum suction head

162. 164 is height adjustable or comprises a height adjustable vacuum suction nozzle 161, 163.

The walls 36, 46 of the distance elements 30, 40 comprise multiple openings 35, 45 preferably arranged along the length of the distance elements 30, 40 as shown in Fig. 16. The multiple openings 35, 45 allow air to flow into the space restricted by the bonded air-laid blank 10, the distance elements 30, 40 and the vacuum suction nozzle 161, 163 when a vacuum or suction pressure is applied at vacuum suction nozzle 161 , 163. This flow of air into the defined space creates air turbulence in connection with the portion of the at least one main surface 12, 14 of the bonded air-laid blank 10 present between the distance elements 30, 40. This air turbulence facilitates effective removal of non-bonded natural fibers from the at least one main surface 12, 14 of the bonded air-laid blank 10.

The walls 36, 46 could be directly attached to the vacuum suction nozzle 161, 163. In another embodiment, the walls 36, 46 are indirectly attached to the vacuum suction nozzle 161 , 163 by a respective support element 38, 48 interconnecting the walls 36, 46 and the vacuum suction nozzle 161 , 163 as shown in Figs. 15-16.

In an embodiment, distal portions 32, 42 of the lips 34, 44 are angled to be arranged with a non-zero angle relative the respective at least one main surface 12, 14 of the bonded air-laid blank 10. As a consequence, these distal portions 32, 42 are preferably angled away from the bonded air-laid blank 10. These angled distal portions 32, 42 operate as guides for the bonded air-laid blank 10 to facilitate correct transport of the bonded air-laid blank 10 between the distance elements 30, 40 and the air-permeable conveyor 120 or the downstream conveyor 180 or between distance elements 30, 40 attached to opposite vacuum suction nozzles 161, 163 as shown in Figs. 15-16. In Figs. 15-16, both the upstream and downstream distance elements 30, 40 have angled distal portions 32, 42 of their lips 34, 44. The embodiments are, though, not limited thereto. It is generally preferred if the distal portion 32 of the lip 34 of the upstream distance element 30 is angled with a non-zero angle since this upstream distance element 30 receives the incoming bonded air-laid blank 10 and should thereby guide it past the vacuum suction nozzle 161 , 163. In such an embodiment, the distal portion 42 of the lip 44 of the downstream distance element 40 does not necessarily have to be angled.

As is shown in Fig. 16, the length of the vacuum suction head(s) 162 is, in an embodiment, at least equal to the width W of the bonded air-laid blank 10. In such a case, the vacuum suction head 162 is able to remove non-bonded natural fibers from the complete main surface 12 of bonded air-laid blank 10. It is, though, possible to use a vacuum suction head 162 with a length that is smaller than the width of the bonded air-laid blank 10. In such a case, the vacuum suction head 162 is preferably movable by the previously described transport system 166, see Fig. 11 , to thereby move the vacuum suction head 162 to cover all portions of the main surface 12 of the bonded air-laid blank 10. For instance, the vacuum suction head 162 could be moved transversely along the width direction of the bonded air-laid blank 10 as the bonded air-laid blank 10 is transported past the movable vacuum suction head 162. 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 bonded air-laid blank 10 may 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 bonded 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 bonded air-laid blank 10.

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. 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.

The polymer binder is included to bind the bonded air-laid blank 10 together and preserve its form and structure during use, handling, and storage. In an embodiment, the polymer binder may also assist in building up the foam-like structure of the bonded air-laid blank 10. The polymer binder is, in such an embodiment, intermingled with the natural fibers during the air-lying process forming a fiber mixture. The polymer binder may be added in the form of a powder but is more often added in the form of fibers that are intermingled with the natural fibers in the air-laying process.

In a particular embodiment, the polymer binder is selected from the group consisting of a polymer powder, polymer fibers and a combination thereof.

The polymer binder could be a natural or synthetic polymer binder, or a mixture of natural polymer binders, a mixture of synthetic polymer binders, or a mixture of natural and synthetic polymer binders, but is preferably a thermoplastic polymer binder.

In an embodiment, the polymer binder is made from I) a material selected from the group consisting of polyethylene (PE), ethylene acrylic acid copolymer (EAA), ethylene-vinyl acetate (EVA), polypropylene (PP), polystyrene (PS), such as styrene-butadiene rubber (SBR) or styrene acrylate copolymer, polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyethylene terephthalate (PET), polycaprolactone (PCL), polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly(2-ethyl-2-oxazoline) (PEOX), polyvinyl ether (PVE), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyvinyl acetate (PVAc), polyurethane (PU), copolymers thereof and mixtures thereof, and II) optionally one or more additives.

Hence, in an embodiment, the polymer binder is made of a material selected from the above-mentioned group. In another embodiment, the polymer binder is made of a material selected from the above- mentioned group and one or more additives. In an embodiment, the polymer binder is or comprises, such as consists of, mono-component and/or bicomponent polymer fibers. Bi-component polymer fibers, also known as bico fibers, comprise a first polymer, copolymer and/or polymer mixture and a second, different polymer, copolymer and/or polymer mixture. Most often the bi-component polymer fiber comprises a core made of the first polymer, copolymer and/or polymer mixture and a sheath made of the second polymer, copolymer and/or polymer mixture, although other combinations of two or even more polymers, copolymers and/or polymer mixtures are possible.

In an embodiment, the polymer binder is a thermoplastic polymer binder and preferably selected from the group consisting of a thermoplastic polymer powder, thermoplastic polymer fibers and a combination thereof.

In a particular embodiment, the thermoplastic polymer binder is or comprises, such as consists of, monocomponent thermoplastic polymer fibers made of i) a material selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives. In another particular embodiment, the thermoplastic polymer binder is or comprises, such as consists of, bi-component thermoplastic polymer fibers having a first material, such as a core made of i) a first material, selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives, and a second material, such as a sheath made of i) a second material, typically a different material, selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives. 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 i) a material selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives, and bi-component thermoplastic polymer fibers having i) materials, such as of the core and/or sheath, selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives.

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 mono-component thermoplastic polymer fibers or made of the same materials in the case of bi-component thermoplastic polymer fibers. However, it is also possible to use a thermoplastic polymer binder made of one or multiple, i.e. , two or more, different mono-component thermoplastic polymer fibers made of different materials and/or one or multiple different bi-component thermoplastic polymer fibers made of different materials.

An advantage of using bi-component thermoplastic polymer fibers is that they can have a core with a higher melting point that keeps its fiber form during the binding operation, whereas the sheath melts and becomes tacky. The intact core will support the three-dimensional structure of the bonded air-laid blank 10 and, thus, promote porosity while the melted or tackified sheath will attach to the natural fibers and preserve the strength of the bonded air-laid blank 10.

In an embodiment, the polymer binder is a polymer powder, preferably a thermoplastic polymer powder, made of i) a material selected from the group consisting of PE, EAA, EVA, PP, PS, PBAT, PBS, PLA, PET, PCL, PVA, PEG, PEOX, PVE, PVP, PAA, PMAA, PVAc, PU, copolymers thereof and mixtures thereof, and ii) optionally one or more additives.

It is also, as mentioned in the foregoing, possible to use a thermoplastic polymer binder that is a combination of thermoplastic polymer fibers and thermoplastic polymer powder.

In an embodiment, the bonded air-laid blank 10 comprises the natural fibers at a concentration of at least 70 % by weight of the bonded air-laid blank 10 and the polymer binder at a concentration selected within an interval of from 2.5 up to 30 % by weight of the bonded air-laid blank 10.

In a preferred embodiment, the bonded air-laid blank 10 comprises 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 bonded air-laid blank 10. 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 bonded air-laid blank 10.

In some embodiments, the bonded air-laid blank 10 comprises the polymer binder at a concentration selected within an interval of from 5 up to 30 % by weight of the bonded air-laid blank 10, preferably within an interval of from 10 up to 25 %, such as from 12.5 up to 25 % by weight of the bonded air-laid blank 10, or more preferably within an interval of from 17.5 up to 22.5 % by weight of the bonded air-laid blank 10. It is also possible to have bonded air-laid blanks 10 with a generally lower amount of the polymer binder. In such an embodiment, the bonded air-laid blank 10 comprises the polymer binder at a concentration selected within an interval of from 2.5 up to 10 % by weight of the bonded air-laid blank 10, preferably within an interval of from 2.7 up to 7.5 % by weight of the bonded air-laid blank 10.

The bonded air-laid blank 10 may comprise one or more additives in addition to the natural fibers and the polymer binder. One or more additives could be added to the polymer binder and/or added when producing the polymer binder. Alternatively, or in addition, one or more additives could be added to the natural fibers. Alternatively, or in addition, one or more additives could be added to the natural fibers and the polymer binder, such as during the air-laying process or prior to the air-laying process.

Illustrative, but non-limiting, examples of such additives include electrically conducting or semiconducting fillers, coupling agents, flame retardants, dyes, impact modifiers, etc.

The bonded air-laid blank 10 produced according to the invention has preferably an average thickness W, see Fig. 1 A, of at least 5 mm, and preferably an average thickness of at least 5 mm and at most 200 mm.

In an embodiment, the bonded air-laid blank 10 has an average density selected within an interval of from 20 up to 200 kg/m³.

In an embodiment, the bonded air-laid blank 10 has an average grammage selected within an interval of from 400 up to 15000 g/m².

The bonded air-laid blank 10 as produced according to the method and by the system 100 of the present invention comprises significantly less non-bonded natural fibers as compared to bonded air-laid blanks 10 produced according to prior art technologies, i.e., without any inline vacuum suction system 160. This means that the bonded air-laid blank 10 produce less linting.

The embodiments described above are to be understood as a few illustrative examples of the present invention. It will be understood by those skilled in the art that various modifications, combinations, and changes may be made to the embodiments without departing from the scope of the present invention. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.

Claims

1 . A method of producing a bonded air-laid blank (10), the method comprising: introducing (S1) natural fibers and a polymer binder into a forming head (110); capturing (S2) the natural fibers and the polymer binder as an unbonded air-laid web (20) on an air-permeable conveyor (120) arranged in connection with an outlet (113) of the forming head (110); heating (S3) the unbonded air-laid web (20) to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank (10); and removing (S4) non-bonded natural fibers from at least one main surface (12, 14) of the bonded airlaid blank (10) by at least one vacuum suction head (162, 164) of an inline vacuum suction system (160).

2. The method according to claim 1 , wherein removing (S4) non-bonded natural fibers comprises removing (S4), while the bonded air-laid blank (10) is positioned with a second main surface (14) of the bonded air-laid blank (10) on the air-permeable conveyor (120) or a downstream conveyor (180), nonbonded natural fibers from a first, opposite main surface (12) of the bonded air-laid blank (10).

3. The method according to claim 1 or 2, wherein removing (S4) non-bonded natural fibers comprises removing (S4) non-bonded natural fibers from a first main surface (12) of the bonded air-laid blank (10) by a first vacuum suction head (162) of the inline vacuum suction system (160) and removing non-bonded natural fibers from a second, opposite main surface (14) of the bonded air-laid blank (10) by a second vacuum suction head (164) of the inline vacuum suction system (160).

4. The method according to claim 3, wherein the first vacuum suction head (162) and the second vacuum suction head (164) are aligned along an axis (15) perpendicular to the first and second main surfaces (12, 14) of the bonded air-laid blank (10).

5. The method according to any one of claims 1 to 4, wherein removing (S4) non-bonded natural fibers comprises removing (S4) non-bonded natural fibers from a same main surface (12, 14) of the bonded air-laid blank by an upstream vacuum suction head (162) and a downstream vacuum suction head (162') of the inline vacuum suction system (160), wherein one of the upstream vacuum suction head (162) and the downstream vacuum suction head (162') has a higher suction pressure as compared to the other of the upstream vacuum suction head (162) and the downstream vacuum suction head (162').

6. The method according to any one of claims 1 to 5, further comprising transporting (S20) the bonded air-laid blank (10) past the inline vacuum suction system (160) comprising the at least one vacuum suction head (162, 164).

7. The method according to any one of claims 1 to 6, further comprising (S30) moving the at least one vacuum suction head (162, 164) relative the bonded air-laid blank (10).

8. The method according to any one of claims 1 to 7, further comprising cooling (S40) the bonded air-laid blank (10) by blowing a gas or gas mixture through the bonded air-laid blank (10).

9. The method according to any one of claims 1 to 8, further comprising cutting (S50) the bonded airlaid blank (10) prior to and/or after removing the non-bonded natural fibers.

10. The method according to any one of claims 1 to 9, further comprising creating (S60) air turbulence in connection with a portion of the at least one main surface (12, 14) of the bonded air-laid blank (10) in vicinity of the at least one vacuum suction head (162, 164).

11 . The method according to any one of claims 1 to 10, wherein the at least one vacuum suction head (162, 164) comprises: an upstream distance element (30) comprising a lip (34) having a planar surface configured to abut one of the at least one main surface (12, 14) of the bonded air-laid blank (10) and a wall (36) attached to the lip (34); a downstream distance element (40) comprising a lip (44) having a planar surface configured to abut one of the at least one main surface (12, 14) of the bonded air-laid blank (10) and a wall (46) attached to the lip (44); and a vacuum suction nozzle (161 , 163) arranged between the upstream distance element (30) and the downstream distance element (40) with the walls (36, 46) of the upstream distance element (30) and the downstream distance element (40) attached directly or indirectly to the vacuum suction nozzle (161 , 163).

12. The method according to claim 11 , wherein the wall (36) of the upstream distance element (30) comprises multiple openings (35); and the wall (46) of the downstream distance element (40) comprises multiple openings (45).

13. The method according to claim 1 1 or 12, wherein a distal portion (32) of the lip (34) of the upstream distance element (30) is angled to be arranged with a non-zero angle relative the one of the at least one main surface (12, 14) of the bonded air-laid blank (10).

14. The method according to any one of claims 1 to 13, further comprising: an upstream roller (206) arranged upstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10); and a downstream roller (204) arranged downstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10).

15. The method according to any one of claims 1 to 13, further comprising: an upper upstream conveyor (220) arranged upstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10); and an upper downstream roller (280) arranged downstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10).

16. The method according to claim 15, wherein the upper upstream conveyor (220) is an upper upstream air-permeable conveyor (220) arranged upstream of the heating device (140) and up to the at least one vacuum suction head (162).

17. A system (100) for producing a bonded air-laid blank (10), the system (100) comprises: a forming head (110) comprising: at least one inlet (111 ) configured to receive natural fibers and a polymer binder; and an outlet (113); and an air-permeable conveyor (120) arranged in connection with the outlet (113) to capture the natural fibers and the polymer binder as an unbonded air-laid web (20); a heating device (140) arranged to heat the unbonded air-laid web (20) to at least partly melt the polymer binder and bind the natural fibers to form a bonded air-laid blank (10); and an inline vacuum suction system (160) comprising at least one vacuum suction head (162, 164) arranged to remove non-bonded natural fibers from at least one main surface (12, 14) of the bonded airlaid blank (10).

18. The system according to claim 17, wherein the at least one vacuum suction head (162) is arranged to remove non-bonded natural fibers from a first main surface (12) of the bonded air-laid blank (10) positioned with a second, opposite main surface (14) of the bonded air-laid blank (10) on the air- permeable conveyor (120) or a downstream conveyor (180).

19. The system according to claim 17 or 18, further comprising a vacuum source (130) arranged beneath the air-permeable conveyor (120) to provide a gas suction through the air-permeable conveyor (120) in connection with the outlet (113) of the forming head (110).

20. The system according to any one of claims 17 to 19, wherein the inline vacuum suction system (160) comprises: a first vacuum suction head (162) arranged to remove non-bonded natural fibers from a first main surface (12) of the bonded air-laid blank (10); and a second vacuum suction head (164) arranged to remove non-bonded natural fibers from a second, opposite main surface (14) of the bonded air-laid blank (10).

21. The system according to claim 20, wherein the first vacuum suction head (162) and the second vacuum suction head (164) are aligned along a vertical axis (15).

22. The system according to claim 20 or 21, further comprising a downstream conveyor (180) configured to transport the bonded air-laid blank (10) from the inline vacuum suction system (160), wherein the second vacuum suction head (164) is arranged at a position in between the air-permeable conveyor (120) and the downstream conveyor (180).

23. The system according to any one of claims 17 to 22, wherein the inline vacuum suction system (160) comprises an upstream vacuum suction head (162) and a downstream vacuum suction head (162') arranged to remove non-bonded natural fibers from a same main surface (12) of the bonded air-laid blank (10), wherein one of the upstream vacuum suction head (162) and the downstream vacuum suction head (162') has a higher suction pressure as compared to the other of the upstream vacuum suction head (162) and the downstream vacuum suction head (162').

24. The system according to any one of claims 17 to 23, further comprising a transport system (166) arranged to move the at least one vacuum suction head (162, 164) relative the bonded air-laid blank (10).

25. The system according to any one of claims 17 to 24, further comprising a cooling device (150) arranged to cool the bonded air-laid blank (10) by blowing a gas or gas mixture through the bonded airlaid blank (10).

26. The system according to any one of claims 17 to 25, wherein the at least one vacuum suction head (162, 164) comprises: an upstream distance element (30) comprising a lip (34) having a planar surface configured to abut one of the at least one main surface (12, 14) of the bonded air-laid blank (10) and a wall (36) attached to the lip (34); a downstream distance element (40) comprising a lip (44) having a planar surface configured to abut one of the at least one main surface (12, 14) of the bonded air-laid blank (10) and a wall (46) attached to the lip (44); and a vacuum suction nozzle (161 , 163) arranged between the upstream distance element (30) and the downstream distance element (40) with the walls (36, 46) of the upstream distance element (30) and the downstream distance element (40) attached directly or indirectly to the vacuum suction nozzle (161 , 163).

27. The system according to claim 26, wherein the wall (36) of the upstream distance element (30) comprises multiple openings (35); and the wall (46) of the downstream distance element (40) comprises multiple openings (45).

28. The system according to claim 26 or 27, wherein a distal portion (32) of the lip (34) of the upstream distance element (30) is angled to be arranged with a non-zero angle relative the one of the at least one main surface (12, 14) of the bonded air-laid blank (10).

29. The system according to any one of claims 17 to 28, further comprising: an upstream roller (206) arranged upstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10); and a downstream roller (204) arranged downstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10).

30. The system according to any one of claims 17 to 29, further comprising: an upper upstream conveyor (220) arranged upstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10); and an upper downstream roller (280) arranged downstream of the at least one vacuum suction head (162) and arranged to be in contact with one of the at least one main surface (12) of the bonded air-laid blank (10).

31. The system according to claim 30, wherein the upper upstream conveyor (220) is an upper upstream air-permeable conveyor (220) arranged upstream of the heating device (140) and up to the at least one vacuum suction head (162).

32. The system according to any one of claims 17 to 31 , wherein the at least one vacuum suction head (162, 164) comprises a height adjustable vacuum suction nozzle (161 , 163).