FI20245235A1 - Low density fiber material and method for producing same - Google Patents

Abstract

The present invention concerns a cushioning material, a multilayer cushioning material, methods for the manufacture thereof as well as uses thereof. The cushioning material according to the present invention comprises a three-dimensional fibre network of cellulosic and/or lignocellulosic fibres. The three-dimensional fibre network of the cushioning material comprises cellulosic and/or lignocellulosic fibres in an amount of at least 50 wt-%, has a density in the range of 20−90 kg/m³, and is arranged into a layer having a thickness in the range of 1−150 mm. The multilayer cushioning material comprises at least one such layer and at least one additional further layer.

Description

LOW DENSITY FIBRE MATERIAL AND METHOD FOR THE MANUFACTURE

THEREOF

FIELD

[0001] The present invention belongs to the field of material technology. More specifically, it relates to the field of low-density fibre materials, in particular cushioning and padding materials.

BACKGROUND

[0002] Cushioning materials are used in a wide range of applications, such as in packaging, clothes, home textiles, mattresses, furniture, sports equipment, garments and vehicle interiors. Currently, such cushioning materials are most commonly fossil-based materials, which typically are difficult to recycle and thus contribute to a negative environmental impact when the end of the product lifespan is reached. In cushioning applications, resilient polyurethane foam is a popular choice for its durability and firmness, and to address the above-mentioned problem the use of alternative bio-polyols, recycled polyols and carbon dioxide based polyols is increasing. However, a biobased or recycled di-isocyanate, being the second main component needed for polyurethane production, is not available on industrial scale. There is thus still a need for alternative cushioning — materials with lower environmental impact than fossil-based materials. s [0003] In a sustainability perspective, wood and plant derived materials would be a

N preferred choice. However, at current state, the use of low-density fibre-based networks in

S cushioning has been limited by their poor reversibility after compression. As per current

R understanding in the literature, this is due to irreversible, localized buckling of fibres under

E 25 — compression, which leads to stress re-distribution and fibre displacement in fibre networks 2 (Ketoja et al.). Hence, structures based on natural fibres typically fail to exhibit the

O stiffness-density properties needed in cushioning materials.

N

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SUMMARY OF THE INVENTION

[0004] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0005] According to a first aspect of the present invention, there is provided a cushioning material comprising a three-dimensional fibre network of cellulosic and/or lignocellulosic fibres. The three-dimensional fibre network of the cushioning material comprises cellulosic and/or lignocellulosic fibres in an amount of at least 50 wt-%, has a density in the range of 20-90 kg/m”, and is arranged into a layer having a thickness in the range of 1-150 mm. — [0006] According to a second aspect of the present invention, there is provided a multilayer cushioning material comprising two or more layers, wherein at least one layer comprises a cushioning material according to the first aspect of the invention.

[0007] According to a third aspect of the present invention, the cushioning material according to the first aspect of the invention or a multilayer cushioning material according — the second aspect of the invention is used in furniture, sport equipment, garments, or vehicle interiors.

[0008] According to a fourth aspect of the present invention, there is provided a method for the manufacture of a three-dimensional fibre network. The method comprises the steps of: - providing fibres of cellulosic and/or lignocellulosic material, - forming the fibres of cellulosic and/or lignocellulosic material into a three- 3 dimensional fibre network with a density within the range of 20-90 kg/m?

N and a total content of cellulosic and/or lignocellulosic fibres of at least 50 wt-

S %, calculated from the dry weight of the three-dimensional fibre network, and

N 25 - arranging the three-dimensional fibre network into a layer having a thickness

E of 1-150 mm. 4 [0009] The method of the fourth aspect of the present invention can be applied in the

N manufacture of a cushioning material according to the first aspect of the invention.

N

[0010] According to a fifth aspect of the present invention, there is provided a method for the manufacture of a multilayer material, such as a multilayer cushioning material, the method comprising manufacturing a three-dimensional fibre network according to the method of the fourth aspect of the invention and combining at least one layer of three-dimensional fibre network obtained in the previous step with at least one further layer. The method of the fifth aspect of the present invention can be applied in the manufacture of a cushioning material according to the second aspect of the invention.

[0011] One advantage of the present invention is that the use of fossil-based materials in cushioning applications can be significantly reduced by the inclusion of biobased fibres, i.e, cellulosic and/or lignocellulosic fibres. A further interrelated advantage of replacing such fossil-based materials with biobased fibres is that the cushioning material simultaneously acts as a long-time carbon storage.

[0012] Another advantage of the invention is that the composition and density of the cushioning material can be easily altered for different applications. Further versatility is achieved by combining the cushioning material of the invention in a layered structure, in particular such that adjacent layers have different properties.

[0013] Another advantage of the present invention is that the cushioning material can be recycled in both standalone form and in layered form, for example, in a paperboard recycling process.

[0014] Still another advantage of the present invention is that it provides for the possibility to utilise cellulosic and lignocellulosic fibres in product categories having significantly prolonged fibre lifetime when compared to typical usages, such as paperboard or tissue paper. <

S

A BRIEF DESCRIPTION OF THE DRAWINGS

N [0015] FIGURE 1 illustrates an example of a cushioning material according to at

E 25 — least one embodiment of the invention. Figure 1 presents a single layer cushioning material o which is constituted of a three-dimensional fibre network comprising cellulosic material.

O The cushioning material is thus an example of a cushioning material according to the first

O aspect of the present disclosure, without being limited thereto.

[0016] FIGURE 2 illustrates an example of a cushioning material according to another embodiment of the invention. Figure 2 presents a double layer cushioning material comprising a first and a second layer of a three-dimensional fibre network comprising cellulosic material, whereby the first layer has a density that is different from the density of the second layer, the thickness of the layers being identical. The double layer cushioning material is thus an example of an embodiment according to the second aspect of the present disclosure, without being limited thereto.

[0017] FIGURE 3 illustrates an example of a cushioning material according to another embodiment of the invention. Figure 3 presents a three-layer cushioning material, comprising identical surface layers of a three-dimensional fibre network comprising cellulosic material. The surface layers are arranged on each side of a core layer which is constituted of a three-dimensional fibre network comprising cellulosic material at a different density than the surface layers. The volume ratio of the higher density material to the lower density material is around 1:1. The three-layer cushioning material is thus an example of an embodiment according to the second aspect of the present disclosure, without being limited thereto. For example, the middle layer can be exchanged to a resilient polymer foam layer.

[0018] FIGURE 4 illustrates a further example of a cushioning material according to the second aspect of the present disclosure. The multilayer cushioning material comprises five layers that are symmetrically arranged with respect to the core layer. The core layer is a resilient polymer foam layer. The core layer is arranged between two intermediate layers, that are adjacent to the surface layers. The intermediate and surface layers comprise a + three-dimensional fibre network of cellulosic material, the intermediate layer being thinner

S and denser with respect to the surface layers. The volume ratio of the polymer foam layer

N 25 — to the total volume of the layers comprising cellulosic material is 1:2. The five-layer

O cushioning material is thus an example of an embodiment according to the second aspect

I of the present disclosure, without being limited thereto. a ;

N

&

EMBODIMENTS

[0019] In the present context, the term “fibrous cellulosic material” or “cellulosic fibres” typically refers to cellulosic and/or lignocellulosic fibres. Such fibres may be of plant origin. 5 [0020] Within the present disclosure, the term “cellulosic material” may refer to both or either of cellulosic and lignocellulosic materials. In some embodiments, the fibrous cellulosic and/or lignocellulosic material may be selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and/or bleached or unbleached hardwood chemical pulp, or sawdust. In some preferred embodiments, the fibrous cellulosic and/or lignocellulosic material may be selected from chemical pulp, mechanical pulp, for example chemi-thermomechanical pulp (CTMP) or bleached chemi- thermomechanical pulp (BCTMP), or non-wood pulp. In other embodiments, the fibres comprise semi-chemical pulp, thermomechanical pulp, or recycled pulp. In some embodiments, the pulp may be made from any broad-leaved tree such as a tree from the — betulaceae family, for example birch or aspen, from the salicaceae family, from eucalyptus, mixed tropical hardwood or pines or from any combination of the aforementioned. The pulp may be also made from any conifer such as spruce or pine or from any combination thereof. The pulp may also be made from a combination of broad-leaved trees and conifers.

In another embodiment, the pulp may be made from any annuals such as straw, common reed, reed canary grass, bamboo, sugarcane, bagasse or any grass plant.

[0021] In the present context, the term *indentation hardness” refers the to a materials capacity to withstand force or load. The indentation hardness is a measure of the 3 total force (N) required to produce a specified indentation of a material (herein an

N indentation corresponding to 40 % of the initial thickness). The indentation hardness of a

S 25 flexible material can be measured according to the standards ISO 2439:2008. If not

N otherwise indicated, the indentation hardness as referred to herein is measured using ISO

E 2439:2008, Method A: “Determination of the 40 %/30 s indentation hardness index”. 4 [0022] In the present context, the term “fatigue” refers to a materials resistance to

N irreversible deformation under repeated stress. In other words, the term fatigue used to

N 30 — describe the materials ability to revert into its original shape after repeated force or repeated load has been applied onto the material. Fatigue can be measured as loss in thickness or loss in indentation hardness of the material. The fatigue of a flexible material can be determined by constant-load pounding according to the standard ISO 3385:2014.

[0023] In the present context, the term “compression recovery” refers to a material’s capability to revert into its initial shape after compression. It can be expressed as a percentage of the initial thickness of the material, i.e., the thickness the material reverts to after compression into a predetermined thickness, such as compression into 50 % of the initial thickness of the material.

[0024] In the present context, the term “cushioning material” refers to a material that is able to undergo temporary deformations under (repeating) stress without breaking, i.e., without reaching irreversible or plastic deformation.

[0025] In the present context, the term “resilient” [resilient layer, resilience] refers to the flexible and/or elastic properties of a material. A resilient layer is a flexible and/or elastic layer.

[0026] The present disclosure provides a cushioning material, such as a padding — material, which is suitable for use in a wide range of short-term and long-term applications.

Within the current disclosure, short-term applications refer in particular to single use applications, such as packaging material. Long-term applications, as used herein, refers to applications where the cushioning material is subjected to repeated load over a longer time period, such as one year or more, and the use in products with a predicted lifespan of one — year or more.

[0027] The cushioning material disclosed herein comprises a three-dimensional fibre 3 network, wherein

N - the three-dimensional fibre network comprises cellulosic and/or lignocellulosic

S fibres in an amount of at least 50 wt-%,

N 25 - the density of the three-dimensional fibre network is in the range of 20-90

E kg/m, and

O - the three-dimensional fibre network is arranged into a layer having a thickness

O in the range of 1-150 mm.

S

[0028] The cushioning properties, 1.e., impact or vibration damping properties of the cushioning material, are attributed to the three-dimensional fibre network comprising cellulosic and/or lignocellulosic fibres. Thus, the inclusion of such a fibre network will reduce the need to employ fossil-based material currently used for the purpose.

[0029] In some embodiments, the three-dimensional fibre network comprises cellulosic and/or lignocellulosic fibres in an amount of at least 55 wt-%, such as at least 70 wt-%, for example at least 75 wt-%, at least 80 wt-%, at least 85 wt-% or at least 90 wt-%, calculated from the dry weight of the three-dimensional fibre network layer. In preferred embodiments, the three-dimensional fibre network layer may comprise, for example, 85 wt-%, 90 wt-%, 95 wt-% or 98 wt-% of the fibrous cellulosic and/or lignocellulosic fibres calculated from the dry weight of the layer. When additives are included in the fibrous — network, the amount of cellulosic and/or lignocellulosic fibres in the three-dimensional fibre network may be, for example, up to 60 wt-%, 75 wt-%, 80 wt-%, 85 wt-%, 90 wt-%, 95 wt-%, 98 wt-%, 99 wt-% or 99.5 wt-%, calculated from the dry weight of the three- dimensional fibre network. The term “additive” may herein refer to all kind of components added to the three-dimensional fibre network of cellulosic and/or lignocellulosic material, and may include, for example, chemical substances or alternative materials, such as fillers.

Such additives may be included in the three-dimensional network to, for example, improve the compression recovery of the material or for other functionality, such as to improve the hydrophobicity or flame-resistance of the material, or to prevent bacterial growth. In particular additives may be used to improve the cushioning properties of the material and — durability under repeated stress. Thus, one or more additives, such as a binding agent, a functionalisation agent or a modifier, may be included in the material to improve the reversible deformation, i.e., compression recovery, of the three-dimensional fibre network. + [0030] A high content of cellulosic and/or lignocellulosic fibres in the three-

S dimensional fibre network is advantageous as it reduces the environmental impact of the

N 25 — product when compared to fossil-based cushioning materials. The inclusion of cellulosic

O and/or lignocellulosic fibres in the above amounts also enhances the recyclability and

I biodegradability properties of the material, as at least half of the dry weight of the material a

J thus is recyclable and/or biodegradable. The remainder of the three-dimensional fibre & network layer can comprise or consist of one or more additives for improved reversible

N 30 deformation of the fibre network and/or flexibility, i.e, fibre reversibility after

N compression. Such additives can be selected from, for example, binding agents, binding fibres, functional fibres, bicomponent fibres, foaming agents, functionalisation agents, or cross-linking agents, without being limited thereto. Alternatively, or additionally, other functional additives can be included, such as fire retardants or mould inhibitors, as a few examples. Any additives may be comprised in the three-dimensional fibre network in a total amount of from 0.5—50 wt-%, such as from 0.5 wt-%, 1 wt-%, 2 wt-%, 3 wt-%, 5 wt- % or 10 wt-% and up to 12 wt-%, 15 wt-%, 25 wt-%, 40 wt-% or 50 wt-%, calculated from the dry weight of the three-dimensional fibre network layer.

[0031] In some embodiments, the density of the three-dimensional fibre network is at least 30 kg/m”, such as at least 35 kg/m’, 40 kg/m”, 45 kg/m?, 50 kg/m? or 55 kg/m? and up to 65 kg/m”, 70 kg/m?, 75 kg/m? or 85 kg/m”. At the higher densities of the disclosed range, such as between 70 kg/m? and 90 kg/m”, the material is relatively rigid compared to the lower density range, such as between 20 kg/m? and 50 kg/m. A cushioning material at the lower density range provides for a soft material, i.e., a material showing higher degree of compression when compared to the higher density range material, when being subjected to a similar load. Naturally, the intended end use of such materials can be different and enables the cushioning material to be used in a wide range of applications either alone or in combination with a material of different properties. Most preferred is a cushioning material in the medium density range of 50 kg/m? to 70 kg/m”, as such a material is a versatile cushioning material providing for a good balance between compression recovery and indentation hardness. Even more preferably the density of the cushioning material is in a range of 55 kg/m? to 65 kg/m”. — [0032] Within the present disclosure, the three-dimensional fibre network is arranged into a layer having a thickness in the range of 1-150 mm The cushioning properties are dependent on a combination of the thickness and density of the layer. In + some embodiments, the thickness may be from 5 mm, 10 mm, 15 mm, 20 mm or 35 mm

S up to 70 mm, 80 mm, 100 mm, 120 mm or 150 mm. A relatively thin layer, with a

N 25 thickness in the range of, for example from 1, 3 or 5 mm up to 8, 10 or 15 mm, and at a

O medium or high-density range, can be used either alone or in combination with a softer

I layer, for example such that the thinner and denser layer acts as a supportive layer or a a

J pressure distribution layer. Likewise, such relatively thin layers of low-density materials & may be used either alone, for example in packaging applications, or in in combination with

N 30 — further layers having similar or different properties. Thicker layers, having a thickness in

N the range of, e.g., from 20, 30 or 50 mm up to 100, 120 or 150 mm, can likewise be used either alone or in combination with other layers.

[0033] The cushioning material can consist of a three-dimensional fibre network as described herein.

[0034] In preferred embodiments of the present disclosure, the cushioning material has an indentation hardness in the range of 150-1400 N, preferably 300-1300 N, even more preferably 350-1200 N, such as 450-1200 N, 800—1200 N or 600—1100 N, when determined as 40 %/30 s indentation hardness index according to ISO 2439:2008, Method

A. The above presented indentation hardness is expressed as the force (N) applied when the cushioning material is compressed 40 % from the initial thickness (mm). A material with an indentation hardness within the above range is suitable for cushioning purposes.

[0035] In further preferred embodiments of the present disclosure, the compression recovery, after compression into 50 % of the initial thickness of the cushioning material, is at least 70 %, preferably at least 75 %, even more preferably at least 80 %, such as at least 85 % or at least 90 % of the initial thickness of the cushioning material. A high compression recovery is important in cushioning applications, as the measure directly corresponds to the material’s ability to revert into its initial shape upon removal of a load applied thereon.

[0036] The cushioning material according to the present disclosure can show fatigue properties that are comparable with traditional cushioning materials. When measured using

ISO 3385:2014 (Determination of fatigue by constant-load pounding, 80 000 cycles), the change in thickness of the cushioning material can be in the range of, for example, from -2 %, -4 %, -6 % or -8 % to -15 %, -25 % or -40 %, with respect to the initial thickness of the material. The change in indentation hardness can be, for example, from -0.2 %, -0.5 %, -1 3 %, -5 % or -10 % to -15 %, -30 %, -45 %, -60 % or -90 %, with respect to the initial

N indentation hardness of the material, when determined using the same test (ISO

S 25 3385:2014).

N z [0037] In further embodiments of the present disclosure, the fibres of cellulosic > and/or lignocellulosic material are selected from bleached or unbleached chemical pulp,

N such as bleached or unbleached softwood chemical pulp and/or bleached or unbleached

N hardwood chemical pulp, mechanical pulp, such as chemi-thermomechanical pulp (CTMP)

N 30 — or bleached chemi-thermomechanical pulp (BCTMP), recycled pulp, non-wood pulp, sawdust, or any combinations thereof. Such cellulosic and/or lignocellulosic materials can be provided as paper grade pulp, such as kraft pulp.

[0038] Preferably, the cellulosic and lignocellulosic material is a wood-derived material, even more preferably wood derived pulp. Being renewable, wood derived materials are a sustainable alternative to fossil-based materials, although currently not widely employed in cushioning applications due to poor compression recovery of the fibres. In the context of the present invention, it was discovered that when formed into a three-dimensional fibre network within the density range disclosed herein, cellulosic and/or lignocellulosic fibres can provide reversibility after compression and fatigue properties required from a cushioning material.

[0039] The fibre length of the fibrous cellulosic material may in one example be — larger than 0.5 mm, in another example less than 10 mm, such as 0.5 to 5 mm, for example 1 to 5 mm, or 12.5 mm.

[0040] The term “fibre length” refers to the distance measured along the longest dimension of the fibre.

[0041] As briefly discussed above, the three-dimensional fibre network of cellulosic — material can comprise additives for improved reversible deformation of the fibre network, for improved fibre strength upon compression, improved compression recovery, improved fatigue properties and/or improved three-dimensional stability. In such embodiments, the cellulosic and/or lignocellulosic fibres of the three-dimensional network can be combined with synthetic fibres and, alternatively or additionally, treated with chemical additives, — such as modifiers or binding compositions, i.e., binding agents. The product lifespan can also be extended in this manner, i.e., by improving the fatigue properties of the cushioning material.

S [0042] A binding composition is a composition that allows the cellulosic and/or a lignocellulosic fibres in the fibre network to bind or connect to each other, either directly : 25 — by forming intra-fibre chemical bonds or by fibre interaction via the binding composition. z For example, the binding composition may comprise a binding polymer. The binding + polymer may comprise for example a polyester, such as polybutylene terephthalate and 4 polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations

N thereof. Preferably, the binding agent comprises bio-based polymers, such as polylactic

N 30 acid. In preferred embodiments, the binding polymer is a thermoplastic polymer. This allows for at least partial melting of the binding composition, or a thermoplastic polymer thereof, after formation of the three-dimensional network.

[0043] The binder composition may be provided for example in the form of fibres, pellets of various shapes (spherical, cylindrical, oval etc.), randomly shaped particles, uniformly shaped particles or in the form of a powder. The binding composition may thus simultaneously act as a filler. When included in the form of fibres or particles, the fibre length or the particle size of the binding composition is preferably in the same range or smaller than the fibres of the cellulosic and/or lignocellulosic material. Thus, the fibre average length or the particle average size, referring to the length of the fibre or the cross- section of a particle in its longest direction, is preferably in a range of 0.001 mm-10 mm, such as 0.02 to 5 mm, for example 1 to 5 mm, or 1-2.5 mm. In particular for pellets or powders, the average cross-section (diameter) of the particles may be in the lower range of this interval, such as from 0.001—2 mm, for example, 0.01-1 mm.

[0044] Binder compositions or additives can be applied in dry form, such as dry fibres, pellets, or powders. Alternatively, the binder composition can be applied in wet form, such as in the form of an agueous dispersion, an agueous suspension, or water — solution. The binder composition can be added to the cellulosic and/or lignocellulosic fibres before or during the manufacture of the cushioning material, such as during formation of the fibre network. Preferably, the three-dimensional fibre network comprises less than 20 wt-%, less than 15 wt-%, or even more preferably less than 10 wt-% or less than 5 wt-% of binder composition or binder additive, calculated from the dry weight of — the three-dimensional network of cellulosic and/or lignocellulosic fibres.

[0045] The binding composition or at least part of the binding composition may be formulated to melt upon heating. Preferably the melting point of such binding < compositions is less than 250 °C, such as less than 220 °C, such as less than 200 °C, such

S as less than 150 °C, or in the range 60 to 220 °C. & 25 — [0046] In preferred embodiments the three-dimensional fibre network of cellulosic

N and/or lignocellulosic fibres comprises bicomponent fibres, such as synthetic bicomponent

E fibres or thermoplastic bicomponent fibres. Such bicomponent fibres can function as 3 binding composition within the fibre network and provide for additional functionality, such

S as Improved expected lifespan of the cushioning material. Furthermore, bicomponent fibres

R 30 — may act as binding agent between any adjacent layers in the cushioning material.

[0047] A bicomponent fibre is a fibre that combines two separate components, i.e, a first component and a second component, into a single filament. The components may be,

for example, two separate polymers or a polymer in combination with a naturally derived component, such as a cellulosic material. The two components may be arranged in bicomponent fibres in various ways, for example side-by-side, as a sheath-core structure, as a segmented structure or as a so-called islands-in-the-sea -structure, where one component surrounds several separate sections of the other component. Preferably, the two components are polymers with different properties.

[0048] The first component may comprise a different polymer than the second component. In some embodiments, the molecular weight of the first component differs from the molecular weight of the second component. The polymers of the first component and the second component may be selected from polyesters, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. In some embodiments, both components comprise, independently from each other, a thermoplastic polymer. In some embodiments, the first component comprises cellulose and the second component comprises a thermoplastic polymer.

Bicomponent fibres comprising thermoplastic polymer is herein to be understood as bicomponent fibres wherein at least one of the components comprises thermoplastic polymer.

[0049] In some embodiments, the bicomponent fibre has a sheath-core structure. A sheath-core structure refers to a structure wherein the polymer(s) used in the core- component are completely surrounded by sheath-component(s). The sheath-component may in some examples comprise a different polymer than the core-component. In other embodiments, the molecular weight of the sheath-component differs from the molecular + weight of the core-component. The polymers for the sheath-component and the core-

S component may be selected from polyesters, such as polybutylene terephthalate and

N 25 — polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations

O thereof. In some preferred embodiments, the sheath-component is a thermoplastic polymer.

I The core component may comprise cellulose. In some embodiments, the core component > may comprise a thermoplastic polymer.

N

3 [0050] The cushioning material may comprise a bicomponent fibre having a sheath- < 30 — core structure, such as a bicomponent fibre in which the core component comprises cellulose and the sheath component comprises a thermoplastic polymer.

[0051] The melting point of at least one component of the bicomponent fibre may be less than 250 °C, such as less than 220 °C, such as less than 200 °C, such as less than 150 °C, or in the range 60 to 220 °C. In some preferred embodiments where the bicomponent fibres have a sheath-core structure, the melting point of the sheath-component is lower than the melting point of the core-component. Preferably, the differences between the melting point of the sheath-component and the melting point of the core-component enables melting of the sheath-component while the core-component remains in solid form. The melted sheath-component may provide for inter-fibre connections within the three- dimensional network structure, while the core component remains intact and provides — structural support.

[0052] It is possible to use any bicomponent fibre arrangements that provide a similar effect in which one component of the bicomponent fibre melts, connecting the cellulosic fibres together, and the other component remains intact, providing structural support to the formed fibre network. — [0053] The fibre network of the cushioning material may comprise from 2 wt-%, 3 wt-%, 5 wt-% or 10 wt-% and up to 12 wt-%, 15 wt-%, 25 wt-%, 40 wt-% or 50 wt-% of bicomponent fibres calculated from the dry weight of the fibre network, for example, 2 to wt-%, such as 5 to 15 wt-%, or 3 to 10 wt-%, of bicomponent fibres calculated from the dry weight of the fibre network. 20 — [0054] In further embodiments, the binding composition may be an expandable binding composition, such as expandable microspheres. The expansion may be activated thermally or chemically. Preferably the binding composition comprises thermally a expandable components, such as thermally expandable microspheres. Such thermally

N expandable components can have a sheath-core structure, preferably such that the sheath & 25 — structure comprises thermoplastic polymers. The core structure typically comprises

N hydrocarbons with low boiling points. The binding agent can thus contribute to the

E improved cushioning properties of the three-dimensional network, as it simultaneously 3 provides for binding properties within the three-dimensional fibre network and resilient

S properties caused by the hollow or cellular structure of the binding agent upon expansion,

R 30 thus contributing to improved reversable deformation of the three-dimensional fibre network.

[0055] In further preferred embodiments, the cellulosic and/or lignocellulosic fibres comprise modified cellulosic and/or lignocellulosic fibres. The fibres can be mechanically or chemically modified fibres of cellulosic material, such as structurally modified fibres, non-derivatized modified fibres, or derivatized modified fibres. The fibres can, for example be heat treated or treated mechanically, such as by grinding. Such modified cellulosic and/or lignocellulosic fibres may also include fully or partially regenerated fibres.

Alternatively, or additionally, the fibre modification may include use of a compatibilizer, a cross-linking agent, alkali treatment, acid treatment, solvent treatment, or activation or reaction through chemically charged regions, such as cationization or anionization, without — being limited thereto. Examples of modified cellulosic fibres that may be included for functionality are viscose fibres and micro- or nanofibrillated cellulose.

[0056] In a preferred embodiment, the chemically treated fibres are non-derivatized cellulosic and/or lignocellulosic fibres treated with deep-eutectic solvent (DES).

[0057] A further example of solvent treatment is treatment with alkali, such as sodium hydroxide (NaOH).

[0058] The cushioning material according to the present disclosure can contain additives. In some embodiments, the cushioning material comprises additive chemicals selected from binding agents, barrier agents, flame-retardants, foaming agents, surfactants, mould inhibitors, or combinations thereof. By the addition of additives, such as the above- — mentioned chemicals, the properties of the cushioning material can be modified according to the intended use.

[0059] In some embodiment, the binding agent may include thermoplastic polymers.

S The binding polymer may comprise for example a polyester, such as polybutylene

AN terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene : 25 — or combinations thereof. Preferably, the binding agent comprises bio-based polymers, such z as polylactic acid. Alternatively, or additionally, the binder agent may be a binder > composition as disclosed herein, such as bicomponent fibres or microspheres.

N

O [0060] In some embodiments, the barrier agent may include hydrophobic agents,

O polymeric barriers, sizing agents, coated fibres, and barrier resins. Such barrier agents may form a barrier on individual fibres or fibre bundles of cellulosic material, or on the three- dimensional fibre network. Herein, barrier agents are also interpreted as to include agents providing the fibres with chemical barrier properties, such as water or grease resistance, i.e., without the formation of physical barriers. Thus, the barrier agents may include hydrophobic agents, such as organosilanes, betulin, and betulinic acid, or sizes, such as styrene acrylate — copolymers — (SA), polyurethanes, alkylated urethanes, carboxymethylcellulose and its salts, alkyl celluloses, such as methyl cellulose and ethyl cellulose, styrene/maleic acid copolymer (SMA), di-isobutylene/maleic anhydride, acrylonitrile/acrylate copolymers, a rosin, a wax, such as alkyl ketene dimer (AKD) or paraffin wax, an oil, such as alkenyl succinic anhydride (ASA), or styrene acrylate emulsion (SAE).

[0061] In some embodiments, the cushioning material may comprise at least one flame retardant, which may be selected from the following group: minerals, organohalogen compounds, organophosphorus compounds, inorganic phosphorus compounds, and organic compounds, and combinations thereof. Such a flame retardant may be comprised within the three-dimensional fibre network or in any additional layers of the cushioning material.

[0062] Examples of mineral flame-retardants include: aluminium trihydroxide (ATH), magnesium hydroxide (MDH), huntite and hydromagnesite, various hydrates, red phosphorus, and boron compounds, mostly borates.

[0063] Examples of inorganic phosphorus flame-retardants include ammonium polyphosphate (APP) and melamine polyphosphate (MPP).

[0064] Examples of organic flame-retardants include carboxylic acid and dicarboxylic acids. a [0065] In some embodiments, in particular when the three-dimensional fibre

N network is formed by foam assisted formation, the additive may be selected from foaming

S agents or surfactants known in the art, such as sodium dodecyl sulphate (SDS), polyvinyl

N 25 — alcohol (PVA), polyethylene glycol dodecyl ether (Brij), polyethylene glycol sorbitan = monolaurate (Tween 20), PEG-6 lauramide, alkyl polyglycosides (APG), such as alkyl

O polyglucosides, fatty alcohol ethoxylates, alkylphenol ethyxolates, fatty acid ethyxolates,

O fatty amide ethyxolates, alkyl glycosides, such as alkyl glucosides, sugar based non-ionic

O polymers, such as sorbitan alkanoates, and combinations thereof. — [0066] In some embodiments, mould inhibitors may be added to the three- dimensional fibre network for improved antibacterial properties. Such antimicrobial properties may be derived from fibre treatment or the inclusion of mould inhibitors, such as, propionic acid and salts thereof, sorbic acid and salts thereof, methyl fumarate, and p- hydroxybenzoate compounds.

[0067] In some embodiments, the cushioning material may comprise a protective layer on at least one of its surfaces. The protective layer may comprise, for example, woven fabrics or non-woven fabrics made of natural or synthetic fibres, optionally treated with additives such as a hydrophobic agent, a fire retardant, a mould inhibitor, a binding agent, a barrier agent or combinations thereof. Preferably, the thickness of the protective layer is less than 5 mm or less than 3 mm, such as ranging from 0.1 to 2 mm, for example — ranging from 0.2 to I mm or from 0.3 to 0.5 mm. In one embodiment, the thickness of the protective layer is 0.1 to 0.4 mm. The advantage of having such a protective layer is that it may provide structural strength, for example by protecting the three-dimensional fibrous network from being defibrillated during handling, or may serve as a functional component providing, for example, water repellent properties to the cushioning material, or binding — properties between layers.

[0068] The cushioning material may, in any protective layer thereof, or within the three-dimensional fibre network, comprise one or more additive chemicals. The additive chemicals can be selected from flame-retardants, foaming agents, mould inhibitors, barrier agents, binding agents, or combinations thereof. Preferably, the amount of such additives is — below 40 wt-%, as calculated from the total dry weight of the fibrous cellulosic and/or lignocellulosic material, such as below 30 wt-% below 20 wt-% or below 10 wt-% of the total dry weight of the fibrous cellulosic and/or lignocellulosic material. In some + embodiments, the additive chemical may be mixed to the fibrous cellulosic and/or

S lignocellulosic material prior to forming the three-dimensional fibre network, such as by

N 25 pre-treatment of fibres or by mixing the fibres with additives. In other embodiments, the © additive may be applied to the three-dimensional fibre network after forming such a

I network. Application after forming the three-dimensional fibre network may in some a

J embodiments comprise spraying the additive onto the surface of the fibre network.

N

0 [0069] In further preferred embodiments of the invention, the cushioning material

O 30 comprises cellulosic and/or lignocellulosic fibres in an amount of at least 50 wt-%, such as at least 60 wt-%, at least 75 wt-% or at least 80 wt-%, calculated from the total dry weight of the cushioning material. This provides for a cushioning material wherein at least half of the total weight of the cushioning material, including any additional layers, is derived from renewable sources.

[0070] According to a second aspect of the present invention, the cushioning material is multilayer cushioning material comprising two or more layers, such as 2-10 layers or 2—6 layers, wherein at least one layer comprises the cushioning material as disclosed herein, or in any embodiments or combination of embodiments thereof. In particular, the two or more layers can be cushioning layers. Such a multilayer cushioning structure provides for further diversity in use and for the possibility to adapt the cushioning properties to different applications. — [0071] The multilayer cushioning material, i.e., multilayer cushioning structure, may comprise at least three layers, such as 3—10 layers, in particular 3-5 layers. The multilayer cushioning material may comprise, for example, 3, 4, 5, 6, 7, 8 or 9 layers. Such layers may be comprised of cushioning material that is identical in composition and/or density.

The layers may be of identical or different thickness. Layers of different properties, such as — different composition, density and/or thickness, may be arranged within the multilayer cushioning material in a symmetrical or asymmetrical manner. The layers may, for example be arranged in an alternating manner, such that at least every second layer is a cushioning material of the present disclosure.

[0072] In preferred embodiments of the multilayer cushioning material, at least two of the layers have different composition and/or density, preferably adjacent layers have different composition and/or density. By combining layers with different properties, that is, with different composition and, additionally or alternatively, different density, the 3 multilayer cushioning material can be further optimized for the intended end use. In

N preferred embodiments, such differing layers are arranged in a sandwich structure of at

S 25 — least three layers.

N z [0073] Different composition herein refers to both chemical and physical > composition. In particular, it refers to the composition of the three-dimensional fibre

N network in relation to a further layer. The physical composition may be different in respect

N of at least one of the fibre structure, the fibre length, the fibre composition, or the type of

N 30 cellulosic material, named as a few examples. The chemical composition can be different in relation to any additives or functionalisation agents used, such as the amount of binder or the type of fibre modification used. By different composition is also meant different types of material, such as synthetic materials and biobased materials.

[0074] The softness, i.e., compressibility, of the cushioning material is typically dependent on the density of the three-dimensional fibre network. When the chemical and — physical composition of a fibre network is the same, a lower density will provide a softer material, i.e., a material with a higher degree of compression under the same load, than a higher density material. When providing a multilayer cushioning material, one can take advantage of these differences in properties to obtain desired features. A more dense or harder material can be used to provide mechanical stability, either as an inner layer — providing stability from the core of the multilayer cushioning material, or as one or more outer layers, e.g., surface layers for improved load distribution, thus preventing an inner layer from reaching a point of irreversible deformation, such as a point where fibre buckling occurs. The softer layer may thus provide improved comfort in use, while the more rigid layer can provide for mechanical stability and/or increased lifespan of products comprising the cushioning material.

[0075] In many end use applications of cushioning materials, such as furniture, mattresses, sports equipment, garments and vehicle interiors, the feel of the cushioning material is of high importance. For such products to be successful on the market, it is not necessarily sufficient to provide for adequate cushioning properties, the product must be comfortable in use and fulfil a wide range of different expectations. To fulfil such requirements, it is beneficial to combine layers of different properties. Thus, a multilayer cushioning material intended for furniture, as a non-limiting example, may have a softer + upper layer (contact layer), and a more rigid bottom layer (support layer). The opposite

S order may be applied, for example, in bicycle handles or cushioning inside helmets, as a

N 25 — stable grip or, respectively, a tight fit around the head is expected. The cushioning in these

O applications is typically provided by the bottom layer (support layer), while the upper layer

I (contact layer) is providing a reliable feel. Products that preferably have identical > properties throughout the material may be composed of a core layer and symmetrically

N arranged identical outer layers on each side. A mattress, for example, may comprise a soft

N 30 — core for flexibility and cushioning, two more rigid intermediate layers on each side for

N improved mechanical stability and load distribution, and two soft surface layers on each side of the mattress to provide comfort in use.

[0076] In some preferred embodiments, at least two of the layers have different indentation hardness, preferably adjacent layers have different indentation hardness, when measured according to the standard ISO 2439:2008, method A.

[0077] In further preferred embodiments, at least one layer is a resilient polymer foam layer, such as a resilient polyurethane foam layer. Resilient polymer foam layers, herein referring to soft polymer foam materials known in the art and commonly used in cushioning applications, can be combined with the cushioning material of the present disclosure. Such layers are preferably arranged in a sandwich structure. The inclusion of a resilient polymer foam layer can provide for improved durability and cushioning properties — during use, e.g., fatigue and compression recovery, but still provides for a material having a considerable part made of cellulosic material. When the product has reached its end of life, such layers can be separated and the layers according to the present disclosure can be duly recycled, e.g., in a cardboard recycling process. A polymeric surface layer may also provide for improved moisture resistance. — [0078] In some embodiments, the multilayer cushioning material comprises at least three layers arranged in a sandwich structure, of which layers at least one is a resilient polymer foam layer. In embodiments comprising three layers, the core layer can be a resilient polymer foam layer surrounded by two outer layers of a cushioning material according to the present disclosure. Alternatively, the core layer can be a cushioning material according to the present disclosure surrounded by two outer layers of resilient polymer foam. When the multilayer material comprises more than three layers, such layers may be arranged in an alternating manner, wherein a core layer or an intermediate layer of + resilient polymer foam is surrounded by adjacent layers of cushioning material according

S to the present disclosure, or vice versa.

S 25 [0079] In some embodiments, at least 40%, preferably at least 50%, even more

N preferably at least 60% of the total volume of the multilayer cushioning material is

E constituted by a cushioning material according to the first aspect of the present disclosure, 9 or any embodiments thereof. This provides for a material where at least 40% of the

O material volume is replaced by the biobased alternative of the present disclosure. Thus,

O 30 lowering the environmental impact when compared to fully fossil-based cushioning materials. In tests carried out in the context of the present invention, it was found that the cushioning properties, such as compression reversibility, of such a material can be in the similar range as for conventional, fossil-based, cushioning materials.

[0080] The cushioning material or the multilayer cushioning material of the present disclosure may in some embodiments be provided in a form of a sheet or a slab. Preferably the “sheet” or the “slab” has two opposite planar surfaces which are generally orientated in parallel. The term “slab” or “sheet” may refer to a separate, discrete object or to a layer that forms an integral part of a larger object. In some embodiments, in particular at the higher density range of the material, i.e., at around 70-90 kg/m”, the “slab” or “sheet” may be stiff in its longitudinal direction, 1.e., unrollable. Such stiff structure may provide — mechanical support and/or improved load distribution properties, in particular in sandwich structures. In other embodiments, in particular at the lower density ranges up to 70 kg/m”, the “slab” or “sheet” may be flexible so that it can be rolled. Rollable structure may allow easier handling, for example during transportation and storage.

[0081] The three-dimensional fibre network can extend across the whole thickness — of the cushioning material of the present disclosure, preferably with a substantially uniform distribution of the cellulosic fibres throughout the cushioning material.

[0082] The cushioning material and the multilayer cushioning material as disclosed herein is suitable for a wide range of applications. It may be used in short time applications, such as packaging materials and single use products. Preferably, the cushioning material is used in long term applications as an alternative to currently used fossil-based materials.

[0083] In a third aspect of the invention, the cushioning material according the first

S aspect of the present disclosure, or a multilayer cushioning material according to the

N second aspect of the present disclosure, or any embodiments thereof, is used in furniture, © 25 — sports equipment, garments, or vehicle interiors. = [0084] Thus, the invention additionally relates to products, in particular furniture,

O sports eguipment or garments comprising a cushioning material or multilayer cushioning

O material according to the present disclosure.

N

O

N [0085] As a fourth aspect of the present invention is provided a method for the manufacture of a three-dimensional fibre network. The method of the fourth aspect of the invention is thus a method suitable for the manufacture of a cushioning material according to the first aspect of the present disclosure, or any of the embodiments thereof. The method comprises the steps of: - providing fibres of cellulosic and/or lignocellulosic material, - forming the fibres of cellulosic and/or lignocellulosic material into a three- dimensional fibre network with a density within the range of 20-90 kg/m? and a total content of cellulosic and/or lignocellulosic fibres of at least 50 wt- %, calculated from the dry weight of the three-dimensional fibre network, and - arranging the three-dimensional fibre network into a layer having a thickness of 1-150 mm.

[0086] In the above method, some of the steps may be performed simultaneously. In particular the steps of forming the fibres into a three-dimensional network and arranging the three-dimensional fibre network into a layer may take place in a single method step, whereby the fibre network is formed into the shape of a sheet, mat, or slab. Preferably, the method includes a step of contacting the fibres of cellulosic and/or lignocellulosic material — with an additive for improved reversible deformation. Such a step is preferably carried out before the formation of the fibre network. The step of contacting the fibres with an additive may also be carried out simultaneously with the step of providing fibres of cellulosic and/or lignocellulosic material, simultaneously with the step of forming a three- dimensional fibre network, or as post-treatment after the three-dimensional fibre network has been formed.

[0087] In some embodiments, the three-dimensional fibre network may be formed from dry cellulosic and/or lignocellulosic material. In an embodiment, the three- dimensional fibre network has been obtained by a web forming method, typically on a

N wire, such as dry forming (dry-laid process), air-laid process or foam forming or any & 25 — combination thereof, preferably by an air-laid process or by dry forming. Advantages of

N using a dry-laid process, in particular an air-laid process, are that the obtained fibre z network is easy to handle, shows homogeneous fibre distribution, and can be directly 3 obtained in a desired thickness. Air-laying processes also allow for uniform inclusion of

S dry state additives, such as thermoplastic additives, polymeric fibres, or bicomponent

R 30 fibres.

[0088] In preferred embodiments of the invention, the fibres of cellulosic and/or lignocellulosic material are selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and/or bleached or unbleached hardwood chemical pulp, mechanical pulp, such as chemi-thermomechanical pulp (CTMP) or bleached chemi-thermomechanical pulp (BCTMP), recycled pulp, non-wood pulp, sawdust, or any combinations thereof. Pulp is a readily available, fully biodegradable and cost-efficient material that is easy to transport. In some embodiments, the three- dimensional network, which can be applied as cushioning material or at least a fibrous part thereof, is formed from dry cellulosic material. Such cellulosic material is preferably paper grade pulp, i.e., pulp suitable for use in paper and/or cardboard manufacture. For example, baled pulp or fluff pulp may be used as the cellulosic material, preferably baled pulp.

[0089] In some embodiments of the invention, the step of providing cellulosic and/or lignocellulosic fibres comprises dry-milling the cellulosic and/or lignocellulosic material.

The inclusion of a dry-milling step, such as a hammer-milling step, in the method provides for a finely separated fibre matrix, which therefore is well suited for the formation of low- density fibre networks as disclosed herein. This pre-processing step is especially preferable —when using dry-laying techniques in the formation of the three-dimensional fibre network, in particular in combination with air-laying techniques. A dry-milling, e.g., hammer- milling step can be included when baled pulp is used as raw material.

[0090] In some embodiments of the invention, the step of contacting the fibres of cellulosic and/or lignocellulosic material with an additive for improved reversible deformation includes the addition of binding agent, such as binding polymers.

[0091] The cellulosic fibres can be contacted with binding agent in wet state, such as an agueous solution or suspension of binding agent. Such binding agent can be mixed with 3 the cellulosic fibres in wet state, such as into wet pulp, or it may be applied through other

N technigues known in the art, such as by spraying. Wet treatment of fibres is in particular

S 25 — suitable in combination with foam forming techniques. When the three-dimensional fibre

N network is formed using dry-forming technigues, an additional drying step can be

E employed for cellulosic fibres treated with additives in wet state or solvents. 4 [0092] The binding agent can additionally or alternatively be applied in dry state,

N such as by inclusion of binding composition in the form of, for example, particles, fibres,

N 30 — or powder. Inclusion of binding agent, i.e., binding composition, in dry state is preferred especially when using dry-laying technigues, in particular air-laying. Within the context of the current disclosure, the term *binding agent” is used interchangeably with the term

“binding composition”. In such applications, the dry state additive can be premixed with dry state lignocellulosic and/or cellulosic fibres prior to formation of the three-dimensional fibre network. Alternatively, or additionally, the additive may be applied during the formation of the three-dimensional fibre network. For example, the addition of dry state additive may be an integrated part of an air-laying process where the additive is mixed with dry pulp fibres prior to settling on a substrate, typically a wire.

[0093] Preferably, a heat treatment step is performed on the three-dimensional fibre network. Such a heat treatment step can be performed to remove any excess moisture, and in particular, to melt and/or activate any additive. When thermally reactive additives, such — as additives comprising thermoplastic polymers or expandable microspheres, are included in the fibre network, the heat treatment can be carried out at a temperature above the melting point or activation point of the additive, such as temperatures up to 250 °C, up to 220 °C, up to 200 °C, up to 150 °C, or in the range 60 to 220 °C. Such a heating step may be carried out by methods known in the art, for example by heating in an oven. — [0094] The above-described method steps can likewise be employed for other additives as listed herein, such additives being provided in dry state or in wet state.

[0095] In some embodiments of the present disclosure the step of contacting the fibres of cellulosic and/or lignocellulosic material with additive for improved reversible deformation is carried out by formation and/or inclusion of bicomponent fibres, preferably — bicomponent fibres comprising a thermoplastic polymer. Such bicomponent fibres may be formed by modifying cellulosic and/or lignocellulosic fibres into bicomponent fibres.

Alternatively, or additionally, bicomponent fibres can be mixed with the cellulosic and/or

N lignocellulosic fibres prior to or during the formation of the three-dimensional fibre

N network.

S

© 25 [0096] In some embodiments of the present disclosure, the step of providing fibres

E of cellulosic and/or lignocellulosic material or the step of contacting the fibres of cellulosic > and/or lignocellulosic material with additive for improved reversible deformation

N comprises chemical and/or physical modification of the fibres of cellulosic and/or

N lignocellulosic material. Such chemical and/or physical modification can include processes

N 30 — known int the art, in particular any fibre modification as disclosed herein, such as mechanical grinding, cross-linking, solvent treatment, regeneration, or modification through chemical charges, or any combination thereof.

[0097] In the method of the present disclosure, a step of contacting the fibres of cellulosic or lignocellulosic material may comprise contacting the fibres with one or more additive selected from barrier agents, flame-retardants, foaming agents, surfactants, mould inhibitors, or combinations thereof. Such additives may be added in wet form, such as in the form of aqueous solutions or dispersions. Alternatively, or additionally, additives may be contacted with the fibres in dry form, such as in the form of particles, powders, or fibres.

[0098] In preferred embodiments of the invention, the step of forming the fibres into a three-dimensional fibre network is carried out using an air-laying technique. In such methods, a step of contacting the fibres of cellulosic and/or lignocellulosic material with an additive for improved reversible deformation can be carried out in the air-laying step, such that an additive for improved reversible deformation is mixed with the cellulosic and/or lignocellulosic fibres in dry state.

[0099] As discussed above, air-laying techniques allows for the formation of a — uniform fibre network. Furthermore, when using air-laying techniques, bicomponent fibres or other additives in dry state may be combined with the cellulosic and/or lignocellulosic fibres upon formation of the air-laid fibre network. In this manner, no separate mixing is required, as the cellulosic and/or lignocellulosic fibres and the additive, such as bicomponent fibres, may be contacted with each other upon web formation, i.e., by supplying the fibres and the additive from different containers to the air-laying process.

This also allow for uniform inclusion of the additive in the fibre network, and in particular with respect to bicomponent fibres and/or polymer fibres it allows for such fibres to be + arranged within the network in a similar manner as the cellulosic material. Such a uniform

S fibre distribution provides for even cushioning properties across the entire fibre network.

N 25 — Air-laying technology can be used in the formation of three-dimensional fibre network

O layers in thickness ranges as disclosed herein.

E [0100] In a preferred embodiment of the method of the present disclosure, the fibres 2 of cellulosic and/or lignocellulosic material are paper grade pulp fibres, preferably 3 provided as baled pulp. The preferred embodiment further comprises dry-milling the pulp < 30 fibres, feeding the dry-milled pulp fibres and a dry state additive to an air-laying process, preferably from separate feed sources, forming a three-dimensional air-laid fibre network of pulp fibres and additive, and subjecting the three-dimensional fibre network to a heat-

treatment step. By applying a heat treatment step the temperature of the three-dimensional fibre network can be increased to a level above the melting point, or activation point, of at least one additive or any component thereof.

[0101] Paper grade pulp fibres herein refers to pulp fibres suitable for paper and/or cardboard manufacture, in particular any commercial pulp to be used in such processes.

The inclusion of a dry-milling step, in particular a hammer-milling step, provides for a finely separated pulp matrix, that is well suited for air-laying. By obtaining a pulp matrix having a high degree of disintegrated, individual fibres provides for a uniform fibre distribution within the air-laid material. It also provides for the possibility to include dry — state additive, in particular provided from separate feed sources as described above. Dry state additives, such as polymeric fibres, can thus be fed directly to the air-laying process, without any preliminary blending of the cellulosic fibres and additive. Thus, an even guality fibre network can be obtained in a simplified process, using currently available eguipment without the need for retrofitting. The additives may further be melted or activated within the air-laid fibre network, for example by heat treatment.

[0102] In some embodiments, the step of forming the cellulosic fibres into a three- dimensional fibre network is carried out using a foam forming technique. The foam forming technique, i.e., use of foam assisted forming technology, allows for inclusion of additives in wet state without applying further drying steps prior to the formation of the fibre network. By forming the three-dimensional fibre network in wet state by foam assisted web formation, it is also possible to utilise the aqueous medium for chemical modification or additive transfer. The use of an aqueous medium can increase the chemical + reactivity when compared to dry state formation, whereby different types of fibre

S interaction can be achieved, when compared dry-formation. Foam forming technology can

N 25 — be used in the formation of three-dimensional fibre network layers in the thickness ranges

O as disclosed herein.

E [0103] In some embodiments, the three-dimensional fibre network is obtained by a 9 foam process carried out on a wire. Such a three-dimensional fibre network can be

S included in or constitute a cushioning material according to the present disclosure. & NU MUUN — [0104] In another embodiment, the three-dimensional fibre network is obtained by a mould-assisted forming method, such as by a foam-forming method in a mould.

[0105] In some embodiments, the three-dimensional fibre network is obtained by continuous web forming or by mould-assisted forming.

[0106] Such a foam formed three-dimensional fibre network can be included in or constitute a cushioning material according to the present disclosure.

[0107] It is to be understood that individual method steps as disclosed herein can be exchanged or combined with further steps. For example, any mechanical treatment, such as hammer milling or grinding, can be applied or exchanged with similar processing steps for producing a fibre matrix with a higher content of disintegrated, individualised fibres. The three-dimensional fibre network formed in the method as presented above, or any embodiment thereof, may also undergo further processing steps post formation. The fibre- network may, for example be coated, spray treated, moisture balanced, consolidated, heat treated, etc. The surface of the fibre network can, for example be treated such that it is non- planar, thus comprising regular or irregular patterns, which may be provided, for example, for improved airflow (breathability) of the material. Such patterns may comprise, for example, grooves or knobs. The patterns may be produced by use of pressing techniques and/or heat treatment. For additional layers, or other fibrous materials which do not need to exhibit cushioning properties, the three-dimensional fibre network may be formed in or compressed to a higher density than the ranges disclosed herein. Such materials may thus function, for example, as substrate layers or protection layers providing stability to the — three-dimensional fibre network as presented herein. Likewise, the method may be applied for the production of fibre-networks with a density below the range as disclosed herein.

Such low-density fibre networks may be used in combination with or as a layer of the + cushioning materials as disclosed herein.

S

N [0108] In a fifth aspect of the disclosure, a method for the manufacture of a

S 25 — multilayer material comprising a three-dimensional fibre network is provided. The method

N of the fifth aspect of the present disclosure is thus suitable for the manufacture of a

E multilayer cushioning material in accordance to the second aspect of the present disclosure. 9 Such a method comprises the step of manufacturing a three-dimensional fibre network

O according to the method of the third aspect of the present disclosure, or any embodiments

O 30 thereof, and combining at least one layer of three-dimensional fibre network obtained in the previous step with at least one further layer. Such at least one further layer is preferably a further cushioning layer, whereby a multilayer cushioning material is obtained. By combining two or more layers, such as 2—10 layers, or 3—5 layers, a multilayer structure (multilayer material) can be obtained. The different layers can be adhered to one another using binding agent. Adjacent fibre layers also can be arranged such that interlayer fibre connections are generated, such as by porous surfaces preventing layers from gliding apart.

Alternatively, or additionally, the multilayer material can comprise a protective layer. Such a protective layer, i.e., surface layer, may also have the function of keeping different layers together within the multilayer material. For example, a woven or non-woven fabric may function as such a surface layer.

[0109] The multilayer material can comprise further additional layers. An additional layer may also comprise for example an adhesive, which joins two adjacent layers together. In some embodiments, the multilayer material comprises an additional layer between two, three, four or all layers of the material. The additional layer may comprise or consist of an adhesive resin. The adhesive resin may be provided in the form or a dry powder, for example as a hot melt adhesive, or as a liguid or as a combination thereof. — [0110] In preferred embodiments of the manufacturing method, the a at least one further layer has different composition and/or density when compared to the at least one layer of three-dimensional fibre network produced in accordance to the fourth aspect of the present disclosure. Such a multilayer material, i.e., multilayer structure, thus preferably comprises at least one layer of cushioning material according to the first aspect of the present disclosure. By combining layers of different composition and/or density in the manufacturing method, the properties of the multilayer material can be optimised for the intended end use, in particular, optimal cushioning properties and durability may be achieved. 3

N [0111] In further preferred embodiments of the manufacturing method, the layers are

S 25 arranged such that adjacent layers have different indentation hardness, measured according

N to ISO 2439:2008, Method A. In this manner, a versatile material for cushioning purposes

E can be obtained, wherein the properties of different layers can complement each other.

LO

N [0112] In some embodiments, the at least one further layer is a resilient polymer

N foam layer, such as a resilient polyurethane foam layer. The inclusion of a resilient

N 30 polymer foam layer, such as a conventional, fossil-based cushioning layer, can be beneficial in some applications. By combinatory designs, key material properties, such as reversible deformation or springback, can be tuned to required and desired levels. It is thus possible to obtain a similar feel as for traditional materials, for example on the surface of the multilayer material, still requiring, for example, 40—60 % less fossil-based materials than in conventional, fossil-based cushioning materials.

[0113] In some embodiments, the layers are adhered to each other through heat treatment to at least partially melt and/or activate any binder compositions and/or bicomponent fibres within the three-dimensional fibre network, by means of adhesives, or by mechanical attachment. By heating the multilayer material, or the surfaces of individual layers, to a temperature above the melting point of a binder composition and/or a at least one component of the bicomponent fibres contained therein, the layers may be adhered to — one another upon being contacted in the still melted stage. Alternatively, or additionally, adhesives, such as glues or sizing agents, can be used for adhering layers. Further possibilities include adhesion through mechanical means, such as by sewing.

[0114] Examples

[0115] In the following, non-limiting examples of the present disclosure are presented. The examples are only intended to illustrate the properties and functionality of the cushioning material of the present disclosure, without being restricted thereto. Thus, any method steps and compositions as presented herein can be combined with other features of the present disclosure.

[0116] Example 1 — Formation of air-laid three-dimensional fibre network — [0117] Three-dimensional fibre networks were prepared according to the present disclosure at different densities using the same composition and the same formation 3 technique (air-laying). &

N [0118] The cushioning material was prepared from pulp fibres (Metsä Pine). The 5 paper grade pulp fibres were provided in the form of pulp bales and hammer-milled prior : 25 — to being subjected to an air-laying process for the formation of a three-dimensional fibre > network. g

W [0119] Bicomponent fibres comprising biobased polyethylene (Bio-PF) and recycled

O polyethylene terephthalate (PET) were provided. The bicomponent fibres were blended with the hammer-milled pulp fibres in the air-laying process.

[0120] The pulp fibres and the bicomponent fibres were supplied to the process from different sources and thus blended in the airspace prior to being settled into a three- dimensional fibre network. Thus, no pre-blending of the fibres was needed. The bicomponent fibres of Bio-PE and recycled PET were included in the three-dimensional fibre network in a total amount of 15 wt-%, calculated based on the dry weight of the fibre network. The air-laying process was carried out such that the thickness of the obtained mat was around 50 mm. The air-laid fibre network was subjected to thermal treatment at a temperature or 150 °C.

[0121] The obtained fibre network was a resilient and durable layer, having an — uniform fibre distribution.

[0122] Example 2 — Properties of air-laid material

[0123] Two different pulp mats were produced using the technique and composition presented in Example 1. The first mat (herein referred to as sample N1) was obtained in a density of 38 kg/m? and the second mat (herein referred to as sample N2) was obtained in a — density of 67 kg/m? The thus obtained cushioning materials were cut into test pieces having a size of 400 mm x 400 mm x 50 mm.

[0124] The materials were subjected to tests for determination of fatigue and indentation hardness properties. Reference tests were performed on a reference material of polyurethane foam

[0125] Determination of the fatigue by constant-load pounding according to ISO 3385:2014 was carried out on each test piece. The fatigue was determined in a dynamic a test of 80 000 cycles. The test pieces were subjected to a force of 750 N, with a repetition

N of the compression cycle 60 times per minute, and using a test probe having a diameter of

S 250 mm. The thickness of the material was determined between every 10 000 cycles. &

I 25 [0126] Further, each test piece was subjected to tests for determination of the - indentation hardness according to ISO 2439:2008, method A. The indentation hardness is 3 herein expressed as a force (N) by which the cushioning material is compressed 40 % from 3 the initial thickness (mm). The measurement probe used to compress the material had a

N diameter of 200 mm. The initial indentation hardness was determined for the fibre — material, i.e., at the beginning of the fatigue test. A reference value was obtained for the material after it had been subjected to repeated stress, i.e., after 80 000 compression cycles performed in the above-described fatigue test.

[0127] All tests were performed under test conditions of a temperature of 23°C and a humidity of 50 % Rh.

[0128] The results of the tests carried out on the material N1, having a density of 38 kg/m? are presented in Table 1.

[0129] The results of the tests carried out on the material N2, having a density of 67.3 kg/m”, are presented in Table 2.

[0130] The results of the tests carried out on the material E30, being a polyurethane foam with a density of 27 kg/m?, are presented in Table 3.

Table 1: Test results for N1 (pulp fibre and bicomponent fibre, density 38 kg/m?)

Thickness Change in Indentation Change in

Cycles (mm) thickness (%) | hardness (N) indentation hardness (%)

Cv [er [vw i

S 60 000

A

N

I

=

LO

™

N

LO

+

N

O

N

Table 2: Test results for N2 (pulp fibre and bicomponent fibre, density 67 kg/m?)

Thickness Change in Indentation Change in hardness (%) eps. 1. sw | os | eo sw | mos | was

Table 3: Test results for E30 (polyurethane foam, density 27 kg/m?)

Thickness Change in Indentation Change in hardness (%) e | 8 [| 0] as

S

: : 2

S

[0131] From the tests it could be concluded that under repeated compression, the fibre based cushioning material prepared from pulp fibres and bicomponent fibres (15 wt-

%) at a density just above 65 kg/m? and thickness around 50 mm performed at a similar level with polyurethane foam with a density around 30 kg/m? and a thickness of around 50 mm. The respective changes in thickness were -8 % for fibre-foam and -3 % for polyurethane foam after 80 000 compressions.

[0132] Example 3 — Foam assisted forming

[0133] Three-dimensional fibre networks were prepared in accordance to the present disclosure using foam assisted formation. The three-dimensional fibre network was prepared from pulp fibres (Metsä Strong).

[0134] The samples were prepared by soaking the pulp fibres in water overnight, — whereafter the fibres were disintegrated for 1 hour. The pulp was placed in a vessel and the fibre foam was generated using a laboratory mixer. Simulsol™ SL10, which is a non-ionic non-ethoxylated surfactant prepared from glucose and fatty alcohol, was added in an amount of 1.2 g/l. The target pulp concentration before foam generation was 4 %. The foam generation time was 3 min with a rotational speed of 3800 rpm and additional 3 min — with 4500 rpm.

[0135] The fibre foam obtained was poured along with a tilted plate into a mould.

After the foam generation, the foam was left to drain for about 15 min in ambient conditions. The samples were dried at 70 *C in an oven. The dried sheets were rewetted to reach a solid content of 50 % by spraying water on the top and the bottom surfaces. The — samples were then placed in a plastic bag and the moisture content was allowed to balance for 4 h, turning the sample after 2 h. The samples were compressed between metal plates to a final thickness of around 30 mm. The thickness of the samples was changed slightly to < achieve the target density of 60 kg/m*. The samples were thereafter dried at 70 °C in an

S oven.

S 25 [0136] The three-dimensional fibre networks thus obtained had planar surfaces with

N even properties, i.e., no denser or flatter regions could be observed. The properties of the

E fibre-networks were essentially the same over the whole cross-section of the material. 4 [0137] Example 4 — Preparation of multilayer material

N [0138] A fibre foam was prepared using the raw material and method presented in

N 30 Example 3, with the exception that the foam generation time was shortened to 1 min with a rotational speed of 4500 rpm. This was to obtain a slightly denser material, to achieve a total density of the multilayer material in the same range as for the materials obtained using fibres alone.

[0139] A three-layered material was prepared using the fibre foam and a polyurethane (PU) foam layer. The thickness of the PU foam layer was 10.5 mm.

[0140] The bottom layer of the sample was made by foaming the pulp slurry as described above and pouring it into a mould with flat surfaces. The PU foam layer was the placed on the fibre foam. After 5 min, a second layer of fiber foam was added. After 15 min drainage, the sample was removed mould and dried similarly as presented in Example 3. The sample was rewetted and the thickness was adjusted to a total thickness of around 30 mm.

[0141] Example 5 — Properties of foam formed fibre networks and multilayer material

[0142] Fibre-network samples prepared in the above manner, herein referred to as sample A1, were tested for compression strength and recovery. Further, a test piece having a sandwich structure of fibre foam in combination with a core layer of polyurethane (PU) foam was prepared (sample A2). In the sandwich structure, the PU layer constituted 1/3 of the material volume. Test were also performed for a PU layer alone as reference sample (sample R3).

[0143] Sample A2, having a sandwich structure, had a middle layer of PU foam and surface layers made of pulp fibres, in a slightly higher density than sample A1. The density, thickness and mass of the PU foam were 28 kg/m? 10.5 mm and 22.1 g, respectively. The density of the pulp fibre layers was 78 kg/m? so that the density of the whole sample would be 60 kg/m”. The sample was prepared by first foaming the pulp slurry and pouring 3 it into a mould. The PU foam was then placed on the fibre foam. After 5 min, a second

N layer of fibre foam was added. The sample was allowed to drain for 15 min whereafter it

S 25 — was removed from the mould and dried similarly to the other samples.

N [0144] An overview of the properties of the samples prepared are listed in Table 4. = a 3 2

S

Table 4: Properties of samples prepared

Sample | Material Foam air | Weight Grammage | Thickness | Density composition | content after (g/m?) (mm) (kg/m? (20) drying (g)

Al Pulp fibres 43 159 2316 37.3 62 (Metsä

Strong)

A2 Pulp fibre with | 57 147 2044 34.0

PU foam middle layer

R3 PU foam 292 31.5 28

Clee

[0145] The samples were subjected to compression strength and recovery tests. The samples tested were balanced overnight in an air-conditioned laboratory room (23 °C, 50

Rh). The samples were cut into a size of 50 mm x 50 mm using a band saw.

[0146] Cyclic compression tests were carried out using a Lloyd LR10K universal tester (Lloyd Instruments Ltd, Bognor Regis, West Sussex, UK). Both compression strength as well as reversibility from the compression were determined at a degree of compression of 10 % respectively 50 %. The compression speed was 10 % of the sample thickness per minute. For a 30 mm sample, the speed was 3 mm/min for the 10 % < compression and 30 mm/min for the subsequent 50 % compression. In the reversibility

S measurement, the thickness of the sample was determined after the sample was recovered

S to the thickness where the initial force of 0.625 N was reached. Reversibility from the

S 15 compression was determined 1 min after the compression. For each trial point, 5 parallel

E samples were tested. 2 [0147] The compression recovery after 50 % compression measured for the fibre

S samples Al were in the range of 79-81 %. After 10 % compression, the compression

N recovery of the fibre samples A1 was around 97 %.

[0148] The sandwich structure, having a middle layer of PU foam (sample A2), had a compression recovery of 92.3 % after 50 % compression, and thus showed a significantly improved compression recovery when compared to the single layer fibre samples. For the tests performed with 10 % compression, the compression recovery was measured to 98.5 % for the sandwich type sample (A2).

[0149] The PU foam reference showed a compression recovery of around 97 % after both 50 % compression and 10 % compression.

[0150] The compression strength at 50 % compression was also determined for the samples. Sample Al, made of paper grade pulp fibres, showed a compression strength of around 65-75 kPa. At 10 % compression, the compression strength was around 10 kPa.

[0151] When PU foam was used as middle layer, the measured compression strength was around 40 kPa at 50 % compression, thus showing a 44 % lower compression strength when compared to the fibre sample Al. The compression strength of the PU foam reference layer (R3) was slightly below 30 kPa at 50 % compression. The corresponding values measured at 10 % compression were around 6 kPa for the sandwich material (A2) and around 23 kPa for the PU reference sample. — [0152] The 3-layered sandwich-type structure consisting of fibre-foam slabs on the outside and PU foam as the inner layer thus only lost 5 percentage points of reversibility in comparison to a monolayered polyurethane foam at 50 % compression. Similarly, at 10 % compression, reversibility of fibre-based foam (98.5 %) was better compared to polyurethane foam (97 %). In the tests, it was thus discovered that by using a PU foam — layer as middle layer, 66 % of the material volume could be replaced by a biobased cushioning material of the present disclosure without significant loss in cushioning properties. 3 [0153] It is to be understood that the disclosed embodiments are not limited to the

N particular structures, process steps, or materials disclosed herein, but are extended to

S 25 equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts.

N It should also be understood that terminology employed herein is used for the purpose of

E describing particular embodiments only and is not intended to be limiting. 2 [0154] Reference throughout this specification to “one embodiment” or “an 3 embodiment” means that a particular feature, structure, or characteristic described in — connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0155] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified asa separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0156] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following — description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or — described in detail to avoid obscuring aspects of the invention.

[0157] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation

N can be made without the exercise of inventive faculty, and without departing from the a 25 — principles and concepts of the invention. Accordingly, it is not intended that the invention : be limited, except as by the claims set forth below.

E [0158] The verbs “to comprise” and “to include” are used in this document as open

W limitations that neither exclude nor reguire the existence of also un-recited features. The

O features recited in depending claims are mutually freely combinable unless otherwise

O 30 explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", ie. a singular form, throughout this document does not exclude a plurality.

[0159] Unless otherwise stated herein or clear from the context, any percentages referred to herein are expressed as percent by weight based on a total weight of the respective composition.

CITATION LIST

1. Ketoja J. A., Paunonen, S., Pääkkönen, E., Pöhler, T., Turpeinen, T., Miettinen, A.,

Mäkinen, T., Koivisto, J., & Alava, M. (2022). Mean-field approach to compression of thick porous fibre networks. In D. W. Coffin, & W. J. Batchelor (Eds.),

Advances in Pulp and Paper Research, Cambridge 2022: Transactions of the 17"

Fundamental Research Symposium (Vol. 1, pp. 371-388). Pulp & Paper

Fundamental Research Society. <t

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Claims (31)

1. A cushioning material comprising a three-dimensional fibre network of cellulosic and/or lignocellulosic fibres, wherein - the three-dimensional fibre network comprises cellulosic and/or lignocellulosic fibres in an amount of at least 50 wt-%, - the density of the three-dimensional fibre network is in the range of 20-90 kg/m? - the three-dimensional fibre network is arranged into a layer having a thickness in the range of 1-150 mm.

2. The cushioning material according to claim 1, wherein the indentation hardness of the material is 150-1400 N, preferably 300-1300 N, even more preferably 350—1200 N, when determined according to ISO 2439:2008, Method A.

3. The cushioning material according to claim 1 or 2, wherein the compression recovery, after compression into 50 % of the initial thickness of the cushioning material, is at least 70 %, preferably at least 75 %, even more preferably at least 80 % of the initial thickness of the cushioning material.

4. The cushioning material according to any of the preceding claims, wherein the fibres of cellulosic and/or lignocellulosic material are selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and/or bleached or unbleached hardwood chemical pulp, mechanical pulp, such as chemi- thermomechanical pulp (CTMP) or bleached chemi-thermomechanical pulp N (BCTMP), recycled pulp, non-wood pulp, sawdust, or any combination thereof. O A

A 5. The cushioning material according to any of the preceding claims, wherein the © cushioning material comprises cellulosic and/or lignocellulosic fibres in an amount of : 25 at least 50 wt-%, such as at least 60 wt-%, at least 75 wt-% or at least 80 wt-%, > calculated from the total dry weight of the cushioning material. N

0 6. The cushioning material according to any of the preceding claims, wherein the fibre O network comprises bicomponent fibres, such as synthetic bicomponent fibres or thermoplastic bicomponent fibres.

7. The cushioning material according to any of the preceding claims, wherein the cellulosic and/or lignocellulosic fibres comprise modified cellulosic and/or lignocellulosic fibres.

8. The cushioning material according to any of the preceding claims, wherein the cushioning material comprises additive chemicals selected from binding agents, barrier agents, flame-retardants, foaming agents, surfactants, mould inhibitors, or combinations thereof.

9. A multilayer cushioning material comprising two or more layers, wherein at least one layer comprises the cushioning material according to any one of claims 1-8.

10. The multilayer cushioning material according to claim 9, wherein at least two of the layers have different composition and/or density, preferably adjacent layers have different composition and/or density.

11. The multilayer cushioning material according to claim 9 or 10, wherein at least two of the layers have different indentation hardness, preferably adjacent layers have different indentation hardness.

12. The multilayer cushioning material according to any one of claims 9—11, wherein at least one layer is a resilient polymer foam layer, such as a resilient polyurethane foam layer.

13. The multilayer cushioning material according to any one of claims 9-12, wherein at least 40 %, preferably at least 50 %, even more preferably at least 60 % of the total S volume of the multilayer cushioning material is constituted by a cushioning material O N according to any one of claims 1-8. S © 14. Use of the cushioning material according to any one of claims 1-8 or the multilayer E cushioning material according to any one of claims 9-13 in furniture, sport equipment, LO 25 garments, or vehicle interiors. ™ > I 15. A method for the manufacture of a three-dimensional fibre network, the method

O L. N comprising the steps of: - providing fibres of cellulosic and/or lignocellulosic material,

- forming the fibres of cellulosic and/or lignocellulosic material into a three- dimensional fibre network with a density within the range of 20-90 kg/m? and a total content of cellulosic and/or lignocellulosic fibres of at least 50 wt-% calculated from the dry weight of the three-dimensional fibre network, and - arranging the three-dimensional fibre network into a layer having a thickness of 1-150 mm.

16. The method according to claim 15, wherein the method comprises a step of contacting the fibres of cellulosic and/or lignocellulosic material with an additive for improved reversible deformation.

17. The method according to claim 15 or 16, wherein the fibres of cellulosic and/or lignocellulosic material are selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and/or bleached or unbleached hardwood chemical pulp, mechanical pulp, such as chemi-thermomechanical pulp (CTMP) or bleached chemi-thermomechanical pulp (BCTMP), recycled pulp, non- wood pulp, sawdust, or any combination thereof.

18. The method according to any one of claims 15-17, wherein the step of providing cellulosic and/or lignocellulosic fibres comprises dry-milling, such as hammer-milling, the cellulosic and/or lignocellulosic material.

19. The method according to any one of claims 16—18, wherein the step of contacting the fibres of cellulosic and/or lignocellulosic material with an additive for improved s reversible deformation includes the addition of binding agent, such as binding N polymers. S ©

20. The method according to any one of claims 16—19, wherein the step of contacting the I 25 fibres of cellulosic and/or lignocellulosic material with additive for improved - reversible deformation is carried out by formation and/or inclusion of bicomponent 4 fibres, preferably bicomponent fibres comprising a thermoplastic polymer. N S

21. The method according to any one of claims 15—20, wherein the step of providing fibres of cellulosic and/or lignocellulosic material or a step of contacting the fibres of cellulosic and/or lignocellulosic material with additive for improved reversible deformation comprises chemical and/or physical modification of the fibres of cellulosic and/or lignocellulosic material.

22. The method according to any one of claims 15-21, wherein the fibres of cellulosic or lignocellulosic material are contacted with one or more additive selected from barrier agents, flame-retardants, foaming agents, surfactants, mould inhibitors, or combinations thereof.

23. The method according to any one of claims 15-22, wherein the step of forming the fibres of cellulosic and/or lignocellulosic material into a three-dimensional fibre network is carried out using an air-laying technique.

24. The method according to claim 23, wherein a step of contacting the fibres of cellulosic and/or lignocellulosic material with an additive for improved reversible deformation is carried out in the air-laying step, such that an additive for improved reversible deformation is mixed with the cellulosic and/or lignocellulosic fibres in dry state.

25. The method according to claims 23 or 24, wherein the fibres of cellulosic and/or lignocellulosic material are paper grade pulp fibres, preferably provided as baled pulp, the method further comprising: - dry-milling the pulp fibres, - feeding the dry-milled pulp fibres and dry state additive to an air-laying process, - forming a three-dimensional air-laid fibre network of pulp fibres and additive, and s - subjecting the three-dimensional fibre network to heat treatment. O A AN

26. The method according to any one of claims 15—22, wherein the step of forming the : fibres of cellulosic and/or lignocellulosic material into a three-dimensional fibre I 25 network is carried out using a foam forming technique. a O

27. A method for the manufacture of a multilayer material comprising a three-dimensional S fibre network, the method comprising: R - manufacturing a three-dimensional fibre network according to the method of any one of claims 15-26,

- combining at least one layer of three-dimensional fibre network obtained in the previous step with at least one further layer.

28. The method according to claim 27, wherein the at least one further layer has different composition and/or density when compared to the at least one layer of three- dimensional fibre network produced in accordance to any one of claims 15-26.

29. The method according to claim 27 or 28, wherein the layers are arranged such that adjacent layers have different indentation hardness.

30. The method according to any one of claims 27-29, wherein the at least one further layer is a resilient polymer foam layer, such as a polyurethane foam layer.

31. The method according to any one of claims 27-30, wherein the layers are adhered to each other through heat treatment to at least partially melt and/or activate any binder compositions and/or bicomponent fibres within the three-dimensional fibre network, by means of adhesives, or by mechanical attachment. i N O N N ? © N I [an a LO 0 N LO + N O N