Low density fibrous product

Abstract

According to an example aspect of the present invention, there is provided a product comprising: a three-dimensional fibre network of cellulosic and / or lignocellulosic fibres, and thermally expanded microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

Description

Low density fibrous productFIELD

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

[0002] Cushioning materials, or materials exhibiting springback properties, 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

[0003] Until now, light-weight cellulosic fibre materials have had a fibrous tactile feel, high water absorbing capacity and limited springback properties.

[0004] Use of light-weight fibre materials for example in cushioning has been limited by their poor reversibility after compression.

[0005] There is thus a need for alternative materials with springback properties and with lower environmental impact than fossil-based materials.SUMMARY OF THE INVENTION

[0006] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0007] According to a first aspect of the present invention, there is provided a product comprising: a three-dimensional fibre network of cellulosic and / or lignocellulosic fibres, and thermally expanded microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

[0008] According to a second aspect of the present invention, there is provided a product comprising: a three-dimensional fibre network of cellulosic and / or lignocellulosicfibres, and hollow flexible microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

[0009] According to a third aspect of the present invention, there is provided a method comprising the steps of providing a pulp composition comprising cellulosic and / or lignocellulosic fibres; mixing the pulp composition with at least one hydrophobization agent to produce hydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other; mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres; dry-laying the mixture, to obtain a dry-laid structure; and heat-treating the dry -laid structure.

[0010] According to a fourth aspect of the present invention, there is provided a method comprising the steps of providing a pulp composition comprising hydrophobic or hydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobic or hydrophobized cellulosic and / or lignocellulosic fibres from each other; and mixing the hydrophobic or hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres. Thereafter the product comprises either dry-laying the mixture, to obtain a dry-laid structure; and heat-treating the dry-laid structure; or alternatively foam forming the mixture, to obtain a foam-formed structure; and heat-treating the foam-formed structure.

[0011] Various embodiments of the first aspect or the second aspect or the third aspect or the fourth aspect may comprise one or more features from the following bulleted list:• the thermally expanded microspheres may comprise hollow thermally expanded microspheres, such as flexible hollow thermally expanded microspheres.• the thermally expanded microspheres may comprise a polymer shell that encapsulates a volume of a gas.• the thickness of the polymer shell of the thermally expanded microspheres may be in the range 0.01 to 1 pm.• the average particle size (D50) of the thermally expanded microspheres may be in the range 5 to 100 pm, such as 20 to 100 pm.• the thermally expanded microspheres may be distributed throughout the three- dimensional fibre network, preferably substantially uniformly.• the product may comprise at least 50 wt-%, such as at least 60 wt-% of cellulosic and / or lignocellulosic fibres, calculated of the dry weight of the product.• the product may comprise at least 0.1 wt-%, such as at least 0.5 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, or 1 to 30 wt-% of thermally expanded microspheres.• the product may comprise at least 0.1 vol-%, such as at least 1 vol-% of thermally expanded microspheres, calculated of the total volume of the product.• the polymer shell of the thermally expanded microspheres may comprise or consists of a thermoplastic polymer, such as a thermoplastic copolymer based on acrylic monomers.• the thermally expanded microspheres or the polymer shell thereof may act as a binding agent.• the hydrophobization agent may be selected from the following group: fatty acids, rosins, waxes, such as alkyl ketene dimer (AKD) or paraffin wax, oils, such as alkenyl succinic anhydride (ASA), fatty alcohols, fatty acid esters, biopolymers, cationic polyamines, cationic polyethyleneimines (PEI), cationic or non-ionic polyacrylamides, polydimethyldiallylammonium chloride (pDADMAC), maleic anhydride (MA), maleic anhydride grafted polypropylene (MAPP), silanes, alkoxysilanes, organosilanes, betulin, betulinic acid, and derivatives and combinations thereof.• the hydrophobization agent may be alkyl ketene dimer (AKD) or a wax.• the product may comprise bicomponent fibres.• the product may comprise at least 0.1 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, such as at least 10 wt-%, such as 10 to 30 wt-% of bicomponent fibres, calculated of the dry weight of the product.• the density of the product may be in the range of 20 to 250 kg / m3, such as 20-90 kg / m3.• the grammage of the product may be less than 200 g / m2, such as in the range 10 to 200 g / m2.• the cellulosic and / or lignocellulosic fibres may originate from wood, such as from chemical or mechanical wood pulp.• the product may be in the form of a sheet or a slab, such as a rollable sheet or a rollable slab, or in the form of a three-dimensional object, such as a spherical or conical object.• the product may have been obtained by using an air-laid process or a foam forming process.• the product comprises at least 5 wt-% of thermally expanded microspheres, and bicomponent fibres, and the thermally expanded microspheres are distributed throughout the three-dimensional fibre network.• the product is a monolayer product.• the thermally expanded microspheres and the bicomponent fibres are distributed throughout the three-dimensional fibre network, substantially uniformly.• the product has an indentation hardness in the range of 50 to 2000 N, such as 150-1400 N, when determined as 40 % / 30 s indentation hardness index according to ISO 2439:2008, Method A.• the thickness of the product is 1-150 mm.• the step of mixing the pulp composition with at least one hydrophobization agent may be carried out at a consistency of 10 to 40%, such as 10 to 30% of the pulp composition.• said separating step may comprise at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other in a dry state by using a hammer mill.• said separating step may lead to separation of fibres and loosening of inter-fibre bonds in the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to obtain a loose fibrous fluff.• said separating step may comprise debundling the hydrophobized cellulosic and / or lignocellulosic fibres.• after the separating step, hydrophobized cellulosic and / or lignocellulosic fibres may be mixed with bicomponent fibres.• between said mixing step with at least one hydrophobization agent and said separating step, drying the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to a moisture content less than 15 wt-%.• said dry laying may comprise air laying.• the thermally expandable microspheres may comprise a polymer shell that encapsulates a volume of a gas or a liquid, preferably a volume of a gas.• the thermally expandable microspheres may be capable of expanding at least 2 times their original volume upon being heated to a temperature in which the encapsulated gas expands or the encapsulated liquid vaporizes.• said heat treating may lead to an increase of the volume of the thermally expandable microspheres to at least 2 times, such as at least 10 times, such as at least 20 times their original volume.• said heat treating may lead to softening of a polymer shell of the thermally expandable microspheres and / or softening of an outer shell of the bicomponent fibres, preferably to bind the cellulosic and / or lignocellulosic fibres together.• the melting temperature of the outer shell of the bicomponent fibres may be lower than the melting temperature of the polymer shell of the thermally expandable microspheres.• the heat treatment may be carried out in a temperature in the range of 80 to 250 °C, such as 100 to 230 °C.• the heat treatment may be carried out in a temperature that is between the melting temperature of the outer shell of the bicomponent fibres and the melting temperature of the polymer shell of the thermally expandable microspheres.• the heat treatment may be carried out in a temperature that is above the melting temperature of the outer shell of the bicomponent fibres, such as above 120 °C.• the heat treatment may be carried out in a temperature that is below the melting temperature of the polymer shell of the thermally expandable microspheres, such as below 250 °C.• the heat treatment may comprise pressing or calendering the dry-laid structure.• said mixing step with at least one hydrophobization agent may be carried out in wet state, and the subsequent steps of the process are carried out in dry state.• the dry laying may be carried out onto a wire, to obtain a dry-laid sheet, or the dry laying is carried out into a mould, to obtain a dry -laid three-dimensional object.

[0012] Advantages

[0013] The present product may act as a long time carbon storage.

[0014] The present product may be produced by a standard air-laid line without any substantial reconfigurations. This may enable production of the product for multiple applications by a single technology or single manufacturing line.

[0015] The present invention may make it possible to minimize the amount of plastic additives in the product.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGURE 1 shows graphically the thickness of sample products according to some embodiments of the present invention as a function of cycles in fatigue analysis by constant-load pounding.

[0017] FIGURES 2, 3 and 4 are microscope images of products manufactured according to some embodiments of the present invention.EMBODIMENTS

[0018] DEFINITIONS

[0019] 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.

[0020] Unless otherwise stated, properties that have been experimentally measured or determined herein have been measured or determined at room temperature. Unless otherwise indicated, room temperature is 25 °C.

[0021] Unless otherwise stated, properties that have been experimentally measured or determined herein have been measured or determined at atmospheric pressure.

[0022] As used herein, the term “average particle / microsphere size” refers to the D50 value of the cumulative volume distribution curve at which 50 % by volume of the particles / microspheres have a diameter less than that value.

[0023] In the present context, the term “thermally expandable” refers to a material that is capable of volumetrically expanding upon being heated.

[0024] In the present context, the term “microsphere” may refer to a substantially spherical particle having an average particle size in the microscale, i.e. in the range of 0.1 to 100 pm.

[0025] In the present context, the term “indentation hardness” refers to a material’s capacity to withstand force or load. The indentation hardness is a measure of the total force (N) required to produce a specified indentation of a material (herein an indentation corresponding to 40 % of the initial thickness). The indentation hardness of a flexible material can be measured according to the standards ISO 2439:2008. If not otherwise indicated, the indentation hardness as referred to herein is measured using ISO 2439:2008, Method A: “Determination of the 40 % / 30 s indentation hardness index”.

[0026] In the present context, the term “fatigue” refers to a materials resistance to irreversible deformation under repeated stress. In other words, the term fatigue used to 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.

[0027] The present disclosure describes a novel light-weight fibrous material which exhibits rubber-like properties, such as springback properties and rubber-like tactile feel. The material also exhibits hydrophobic properties. The unique combination of these properties provides surprising advantages in several application areas.

[0028] In an aspect, the present disclosure relates to a product comprising: a three- dimensional fibre network of cellulosic and / or lignocellulosic fibres, and thermally expanded microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

[0029] In a further aspect, the present disclosure relates to a product comprising: a three-dimensional fibre network of cellulosic and / or lignocellulosic fibres, and hollow flexible microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

[0030] In a yet further aspect, the present disclosure relates to a method comprising the steps of: providing a pulp composition comprising cellulosic and / or lignocellulosic fibres; mixing the pulp composition with at least one hydrophobization agent to producehydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other; mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres; dry-laying the mixture, to obtain a dry-laid structure; and heat- treating the dry-laid structure.

[0031] In a yet further aspect, the present disclosure relates to a method comprising the steps of providing a pulp composition comprising cellulosic and / or lignocellulosic fibres; mixing the pulp composition with at least one hydrophobization agent to produce hydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other; mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres; foam forming the mixture, to obtain a foam-formed structure; and heat-treating the foam-formed structure.

[0032] Cellulosic and / or lignocellulosic fibres

[0033] In some embodiments, the product comprises at least 50 wt-%, such as at least 60 wt-% of cellulosic and / or lignocellulosic fibres, calculated of the dry weight of the product.

[0034] In some embodiments, the cellulosic and / or lignocellulosic fibres 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 cellulosic and / or lignocellulosic fibres 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 cellulosic and / or lignocellulosic 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.

[0035] In some embodiments of the present disclosure, 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, or any combinations thereof. Such cellulosic and / or lignocellulosic materials can be provided as paper grade pulp, such as kraft pulp. In some embodiments, the cellulosic and / or lignocellulosic material may comprise recycled and at least partially separated (e.g. by hammermill) low density cellulosic material, for example recycled cellulosic and / or lignocellulosic material having average density of less than 300 kg / m3. In some embodiments, the cellulosic and / or lignocellulosic material may comprise pieces, or fragments of recycled cellulosic and / or lignocellulosic articles, such as pieces or fragments of sheets and / or three-dimensional structures of thermoformed fibre articles comprising cellulosic and / or lignocellulosic fibres and thermoplastic polymer.

[0036] Preferably, the cellulosic and / or lignocellulosic fibres 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 some embodiments, 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.

[0037] In an embodiment, the cellulosic and / or lignocellulosic fibres originate from wood, such as from chemical or mechanical wood pulp.

[0038] The fibre length of the cellulosic and / or lignocellulosic fibres 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 1-2.5 mm.

[0039] The term “fibre length” refers to the distance measured along the longest dimension of the fibre.

[0040] In some embodiments, the product comprises cellulosic and / or lignocellulosic fibres in an amount of at least 60 wt-%, such as at least 70 wt-%, such as atleast 75 wt-%, such as at least 80 wt-%, such as at least 85 wt-% calculated from the dry weight of the product. In preferred embodiments, the product may comprise, for example, up to 90 wt-%, such as up to 85 wt-%, such as up to 80 wt-%, such as up to 70 wt-%, such as up to 60 wt-% of the cellulosic and / or lignocellulosic fibres calculated from the dry weight of the product.

[0041] In some embodiments, the cellulosic and / or lignocellulosic fibres can make up to 85 wt-% of the product, although more rubber-like behaviour may be achieved when the amount of cellulosic and / or lignocellulosic fibres is lower, for example less than 70 wt- %, such as less than 60 wt-% of cellulosic and / or lignocellulosic fibres.

[0042] A high content of cellulosic and / or lignocellulosic fibres in the product may be advantageous as it reduces the environmental impact of the product when compared to fossil-based products. The inclusion of cellulosic and / or lignocellulosic fibres in the above amounts may also enhance the recyclability and biodegradability properties of the product, as at least half of the dry weight of the product thus is recyclable and / or biodegradable.

[0043] Thermally expandable or expanded microspheres

[0044] The present product comprises thermally expandable or thermally expanded microspheres or hollow flexible microspheres. The thermally expandable or expanded microspheres may act as internal springs in the structure and / or as a binder between the cellulosic and / or lignocellulosic fibres.

[0045] In the present process, the microspheres may be fed either in an expanded form or in an unexpanded form. During the process the microspheres may be caused to expand to a desired volume.

[0046] In some embodiments, the thermally expanded microspheres comprise hollow thermally expanded microspheres, such as flexible hollow thermally expanded microspheres.

[0047] The expansion may be activated thermally. Such thermally expandable or expanded microspheres can have a sheath-core structure, preferably such that the sheath structure (or the shell) comprises thermoplastic polymers. The core structure typically comprises a gas or a liquid, such as hydrocarbons with low boiling points.

[0048] In some embodiments, the thermally expandable microspheres comprise a polymer shell which encapsulates a volume of a fluid, such as a gas or gases and / or a liquid or liquids.

[0049] The gas or gases may comprise one or more hydrocarbons in gaseous form.

[0050] The liquid or liquids may comprise one or more hydrocarbons in liquid form.

[0051] In some embodiments, the thermally expandable microspheres are capable of expanding at least 2 times their original volume upon being heated to a temperature in which the encapsulated gas expands or the encapsulated liquid vaporizes.

[0052] In an embodiment, the product comprises at least 0.1 wt-%, such as at least 0.5 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, such as at least 10 wt-%, or 1 to 30 wt-% of thermally expanded microspheres.

[0053] In an embodiment, the product, when at room temperature, comprises at least 0.1 vol-%, such as at least 1 vol-% of thermally expandable microspheres, calculated of the total volume of the product.

[0054] In some embodiments, the polymer shell of the thermally expanded microspheres comprises or consists of a thermoplastic polymer, such as a thermoplastic copolymer based on acrylic monomers.

[0055] In some embodiments, the polymer shell of the microspheres may comprise a biodegradable material, such as cellulose or a cellulose derivative.

[0056] The thermally expandable microspheres or the polymer shell thereof may act as a binding agent.

[0057] The diameter of the thermally expandable microspheres may be in the range 5 to 20 pm.

[0058] The thickness of the polymer shell of the thermally expanded microspheres may be in the range 0.01 to 1 pm, for example in the range of 0.05 to 0.5 pm.

[0059] The diameter of the thermally expanded microspheres may be in the range 20 to 100 pm.

[0060] The thermally expandable or expanded microspheres may simultaneously provide for binding properties within the three-dimensional fibre network and resilient properties caused by the expandable or expanded hollow or cellular structure of the microspheres.

[0061] Hydrophobization agent

[0062] The cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent. Treating with hydrophobization agent is performed so that the cellulosic and / or lignocellulosic fibres become hydrophobized. Thus, at least in some embodiments the cellulosic and / or lignocellulosic fibres are hydrophobized. Hydrophobization of cellulosic and / or lignocellulosic fibres can be achieved through any suitable method. For example, a hydrophobization agent may be introduced or mixed with the cellulosic and / or lignocellulosic fibres or the pulp composition.

[0063] In some embodiments, the hydrophobization agent is selected from the following group: fatty acids, rosins, waxes, such as alkyl ketene dimer (AKD) or paraffin wax, oils, such as alkenyl succinic anhydride (ASA), fatty alcohols, fatty acid esters, biopolymers, cationic polyamines, cationic polyethyleneimines (PEI), cationic or non-ionic polyacrylamides, polydimethyldiallylammonium chloride (pDADMAC), maleic anhydride (MA), maleic anhydride grafted polypropylene (MAPP), silanes, alkoxysilanes, organosilanes, betulin, betulinic acid, and derivatives and combinations thereof.

[0064] In some embodiments, the hydrophobization agent is selected from the following group: fatty acids, alkyl ketene dimer (AKD), fatty alcohols, fatty acid esters, biopolymers, cationic polyamines, cationic polyethyleneimines (PEI), cationic or non-ionic polyacrylamides, polydimethyldiallylammonium chloride (pDADMAC), maleic anhydride (MA), maleic anhydride grafted polypropylene (MAPP), silanes, alkoxysilanes, and derivatives and combinations thereof.

[0065] Preferably, the hydrophobization agent is alkyl ketene dimer (AKD) or a wax.

[0066] In an embodiment, the product comprises at least 0.1 wt-%, such as at least 0.5 wt-%, such as at least 1 wt-% of a hydrophobization agent. In some embodiments, the product may comprise for example 0.1 - 5 wt-%, or 0.5 - 3 wt-% of hydrophobization agent, such as alkyl ketene dimer or wax.

[0067] In an embodiment, the density of the product is in the range of 20-250 kg / m3, such as 20-90 kg / m3.

[0068] In an embodiment, the grammage of the product is less than 200 g / m2, such as in the range 10 to 200 g / m2. For example, in some preferred embodiments the grammage of the product may be in the range of 10 to 200 g / m2and the thickness of the product may be less than 10 mm. In other embodiments, the grammage of the product may be in the range of 1700 - 2200 g / m2and the thickness of the product may be 4 to 6 cm.

[0069] In some embodiments, the density of the product is at least 30 kg / m3, such as at least 35 kg / m3, 40 kg / m3, 45 kg / m3, 50 kg / m3or 55 kg / m3and up to 65 kg / m3, 70 kg / m3, 75 kg / m3or 85 kg / m3. At the higher densities of the disclosed range, such as between 70 kg / m3and 90 kg / m3, the product is relatively rigid compared to the lower density range, such as between 20 kg / m3and 50 kg / m3. A product at the lower density range provides for a soft product, i.e., a product showing higher degree of compression when compared to the higher density range product, when being subjected to a similar load. Naturally, the intended end use of such products can be different and enables the product to be used in a wide range of applications either alone or in combination with a material of different properties.

[0070] The product may be in the form of a sheet or a slab, such as a rollable sheet or a rollable slab, or in the form of a three-dimensional object, such as a spherical or conical object. The three-dimensional object may be symmetrical or non-symmetrical.

[0071] The product may be in the form of a sheet or layer having a thickness in the range of 1-150 mm, preferably in the range of 3 to 100 mm, on in the range of 3 to 50 mm. In some embodiments, the thickness may be from 5 mm, 10 mm, 15 mm, 20 mm or 30 mm up to 40 mm, 60 mm, 70 mm, 80 mm, 120 mm or 140 mm.

[0072] In preferred embodiments of the present disclosure, the product has an indentation hardness in the range of 50 to 2000 N, such as 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 product is compressed 40 % from the initial thickness (mm). Aproduct with an indentation hardness within the above range may be suitable for cushioning purposes.

[0073] In further preferred embodiments of the present disclosure, the compression recovery, after compression into 50 % of the initial thickness of the product, 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 product. A high compression recovery may be 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.

[0074] The product 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 present product 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 %, -5 % or -10 % to -15 %, -30 %, -45 %, -60 % or -90 %, with respect to the initial indentation hardness of the product, when determined using the same test (ISO 3385:2014).

[0075] In some embodiments, the product is a monolayer product, monolayer product refers to a product comprising a single layer of material. Preferably the product is substantially uniform, such that the monolayer of the product is substantially uniform.

[0076] Bicomponent fibres as additive

[0077] Preferably the product comprises at least the following components: hydrophobized pulp which forms a three-dimensional fibre network, bicomponent fibres, and thermally expanded microspheres. Advantageously, the thermally expanded microspheres and the bicomponent fibres are distributed throughout the three-dimensional fibre network, preferably substantially uniformly.

[0078] In preferred embodiments the product comprises bicomponent fibres, such as synthetic bicomponent fibres or thermoplastic bicomponent fibres. Such bicomponent fibres can function as binding composition within the fibre network and provide for additional functionality, such as improved expected lifespan of the product.

[0079] 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.

[0080] 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.

[0081] 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 corecomponent 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 corecomponent may be selected from polyesters, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. In some preferred embodiments, the sheath-component is a thermoplastic polymer. The core component may comprise cellulose. In some embodiments, the core component may comprise a thermoplastic polymer.

[0082] The product may comprise a bicomponent fibre having a sheath-core structure, such as a bicomponent fibre in which the core component comprises cellulose and the sheath component comprises a thermoplastic polymer.

[0083] 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.

[0084] 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 and / or lignocellulosic fibres together, and the other component remains intact, providing structural support to the formed fibre network.

[0085] In an embodiment, the product comprises at least 0.1 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, such as at least 10 wt-%, such as 10 to 30 wt-% of bicomponent fibres, calculated of the dry weight of the product.

[0086] The product 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 product, for example, 2 to 20 wt-%, such as 5 to 15 wt-%, or 3 to 10 wt-%, of bicomponent fibres calculated from the dry weight of the product.

[0087] Modified fibres

[0088] In some embodiments, the product comprises 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. 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.

[0089] In a preferred embodiment, the chemically treated fibres are non-derivatized cellulosic and / or lignocellulosic fibres treated with deep-eutectic solvent (DES).

[0090] A further example of solvent treatment is treatment of the cellulosic and / or lignocellulosic fibres with alkali, such as sodium hydroxide (NaOH).

[0091] Additives

[0092] The term “additive” may herein refer to all kind of components added to the product, and may include, for example, chemical substances or alternative materials, such as fillers. Such additives may be included in the product to, for example, improve the compression recovery of the material or for other functionality, such as to improve the 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 product to improve the reversible deformation, i.e., compression recovery, of the product.

[0093] The product according to the present disclosure can contain additives. In some embodiments, the product 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 product can be modified according to the intended use.

[0094] The product can comprise additives for improved reversible deformation, 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 product.

[0095] A binding composition is a composition that allows the cellulosic and / or lignocellulosic fibres in the fibre network to bind or connect to each other, either directly by forming intra-fibre chemical bonds or by fibre interaction via the binding composition. For example, the binding composition may comprise a binding polymer. The binding polymer may comprise for example a polyester, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. Preferably, the binding agent comprises bio-based polymers, such as polylactic 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.

[0096] 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 crosssection 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.

[0097] 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 aqueous dispersion, an aqueous suspension, or water solution. The binder composition can be added to the cellulosic and / or lignocellulosic fibres before or during the manufacture of the product, such as during formation of the fibre network. Preferably, the product 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 product.

[0098] The binding composition or at least part of the binding composition may be formulated to melt upon heating. Preferably the melting point of such bindingcompositions is 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.

[0099] In some embodiments, the binding agent may include thermoplastic polymers. The binding polymer may comprise for example a polyester, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. Preferably, the binding agent comprises bio-based polymers, such as polylactic acid.

[0100] In some embodiments, the binding composition may comprise carboxymethyl cellulose (CMC), starch or combinations thereof.

[0101] In some embodiments, the barrier agent may include polymeric barriers, sizing agents, coated fibres, and barrier resins. Such barrier agents may form a barrier on individual fibres or fibre bundles of the cellulosic and / or lignocellulosic fibres, or on the three-dimensional fibre network. Herein, barrier agents are also interpreted as to include agents providing the cellulosic and / or lignocellulosic fibres with chemical barrier properties, such as water or grease resistance, i.e., without the formation of physical barriers.

[0102] In a further aspect, the present disclosure relates to a method comprising the steps of: providing a pulp composition comprising cellulosic and / or lignocellulosic fibres; mixing the pulp composition with at least one hydrophobization agent to produce hydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other; mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres; dry-laying the mixture, to obtain a dry-laid structure; and heat- treating the dry-laid structure.

[0103] In a further aspect, the present disclosure relates to a method comprising the steps of: providing a composition comprising hydrophobized cellulosic and / or lignocellulosic fibres; at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other; mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres; dry-laying the mixture, to obtain a dry-laid structure; and heat-treating the dry-laid structure.

[0104] In preferred embodiments, between said mixing step with at least one hydrophobization agent and said separating step, the method comprises drying the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to a moisture content less than 15 wt-%.

[0105] Separating the fibres from each other

[0106] The separating step is preferably carried out for dry or dried hydrophobized cellulosic and / or lignocellulosic fibres.

[0107] In an embodiment, said separating step comprises at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other in a dry state by using a hammer mill.

[0108] In an embodiment, said separating step leads to separation of fibres and loosening of inter-fibre bonds in the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to obtain a loose fibrous fluff.

[0109] In an embodiment, said separating step comprises debundling the hydrophobized cellulosic and / or lignocellulosic fibres.

[0110] In an embodiment, after the separating step, the method comprises mixing the hydrophobized cellulosic and / or lignocellulosic fibres with bicomponent fibres.

[0111] Achieving sufficient separation of fibres from each other may be beneficial in view of subsequent introduction of the thermally expandable microspheres into the product structure. After mixing the microspheres with the at least partially separated hydrophobized fibres, the mixture is dry-laid and subsequently heat-treated, and thereby advantageously the microspheres expand and become locked into the fibre network and effectively retained within the structure.

[0112] Heat treatment

[0113] The heat treatment is an important feature of the present process. We have observed that by means of a single heating step it may be possible to achieve multiple advantageous effects. The heat treatment may lead to expansion of the thermally expandable microspheres. Additionally, the heat-treatment may contribute to the functioning of any additives, particularly additives comprising thermoplastic materials. Forexample, in embodiments, the product may comprise bicomponent fibres having a thermoplastic outer shell or outer part. During the heat treatment, the thermoplastic outer shell or outer part may melt, thereby acting as a binder between the cellulosic and / or lignocellulosic fibres.

[0114] In some embodiments, said heat treating leads to an increase of the volume of the thermally expandable microspheres to at least 2 times, such as at least 10 times, such as at least 20 times their original volume.

[0115] In some embodiments, said heat treating leads to softening of a polymer shell of the thermally expandable microspheres and / or softening of an outer shell of the bicomponent fibres, preferably to bind the cellulosic and / or lignocellulosic fibres together.

[0116] In some embodiments, the melting point of the outer shell of the bicomponent fibres is lower than the melting point of the polymer shell of the thermally expandable microspheres.

[0117] In some embodiments, the heat treatment is carried out in a temperature in the range of 80 to 250 °C, such as 100 to 230 °C, preferably for a period of time in the range of 10 seconds to 5 minutes.

[0118] In some embodiments, the heat treatment is carried out in a temperature that is between the melting point of the outer shell of the bicomponent fibres and the melting point of the polymer shell of the thermally expandable microspheres.

[0119] In some embodiments, the heat treatment is carried out in a temperature that is above the melting temperature of the outer shell of the bicomponent fibres, such as above 120 °C.

[0120] In some embodiments, the heat treatment is carried out in a temperature that is below the melting point of the polymer shell of the thermally expandable microspheres, such as below 250 °C.

[0121] The heat-treatment may be carried out in an oven or by microwave heating. Any other suitable means for heating the dry-laid structure may also be employed.

[0122] Advantageously, the microspheres retain their expanded form even after the heat treatment has been ended and the temperature has returned to room temperature. Insome embodiments, the microspheres may be thermally expanded prior to mixing them with the hydrophobized cellulosic and / or lignocellulosic fibres.

[0123] In some embodiments, the process may comprise feeding a reject fraction originating from the process, such as a part of a heat-treated air-laid structure, back to the separating step. The separating step may receive as inputs the hydrophobized fibres, a reject fraction and optionally additives.

[0124] Process for hydrophobization

[0125] The preferred fibrous raw material in the present process is hydrophobized pulp, such as hydrophobized paper-grade pulp.

[0126] Any suitable method may be employed for hydrophobization of cellulosic and / or lignocellulosic fibres. Preferably, a hydrophobization agent is introduced or mixed with the cellulosic and / or lignocellulosic fibres or the pulp composition.

[0127] Preferably, the pulp composition that is mixed with said at least one hydrophobization agent is a wet pulp composition, such as a never-dried wet pulp composition or a composition comprising dried and re-wetted or repulped pulp.

[0128] In an embodiment, the wet pulp composition is mixed with at least one hydrophobization agent, to obtain a mixture of the wet pulp and the hydrophobization agent.

[0129] Preferably, the hydrophobization agent is added to a wet pulp composition which has a consistency larger than 10%, for example less than 40%, such as 10 to 30%.

[0130] Mixing is preferably carried out by a mixing device, such as an easy to use mixing device, typically by using low shear forces. Preferably the mixing device is configured to heat and / or cool the mixture if desired. For example, the hydrophobization agent is injected into the mixing device, to be mixed with the pulp composition.

[0131] The hydrophobization agent may be selected from any of the following groups: a) hydrocarbons and / or hydrocarbon compounds and / or hydrocarbon derivatives, which may be unsaturated or saturated, straight-chain or branched or cyclic, and may havefunctional groups, for example vinyl, alcohol, aldehyde, carboxylic acid as well as ionic and or non-ionic functional groups; b) polymers and their derivatives, such as polyolefins, polyols, polyelectrolytes, polypeptides, polysaccharides and oligomers and / or monomers thereof, for example polydimethyldiallylammonium chloride (pDADMAC); c) low molecular weight compounds, such as amino acids, phenolics, fatty acids, fatty acids based chemicals, alcohols, for example, glycerol, propylene glycol, alkyl ketene dimer (AKD); d) lubricants, waxes, oils, vegetable oils, plant oils; e) organic and inorganic minerals and mineral derivatives, such as calcium carbonate, talc, kaolin, silanes, siloxane, chitin or chitosan; and any derivatives and combinations thereof.

[0132] In one embodiment, the hydrophobization agent is selected from oils and waxes.

[0133] In one embodiment, the hydrophobization agent is alkyl ketene dimer (AKD) or a wax.

[0134] Advantageously, said at least one hydrophobization agent is capable of decreasing surface tension of the fibre surfaces as measured by water contact angle.

[0135] Advantageously, said at least one hydrophobization agent is a hydrophobization agent capable of making the fibres or fibre surfaces more hydrophobic. Preferably said at least one hydrophobization agent is a hydrophobization agent which makes the fibres or fibre surfaces more hydrophobic, preferably so that the water contact angle of the fibres becomes at least 100°, such as at least 110°, such as at least 120°, such as at least 130°.

[0136] Further additives

[0137] In some embodiments, the method includes a step of mixing the cellulosic and / or lignocellulosic fibres or the pulp composition with a further additive beside the hydrophobization agent. Such a step is preferably carried out before the dry-laying step.The step of mixing the cellulosic and / or lignocellulosic fibres with a further additive may also be carried out simultaneously with the dry-laying step, or as post-treatment after the dry-laying step.

[0138] In some embodiments, the further additive may be selected from carboxymethyl cellulose (CMC), starch or combinations thereof. Preferably, after the separating step, the method comprises mixing the cellulosic and / or lignocellulosic fibres with bicomponent fibres. This step may be carried out before, after or simultaneously with the step of adding the microspheres. Thereafter the dry -laying step may follow.

[0139] In some embodiments, the three-dimensional fibre network may be formed from dry and hydrophobized cellulosic and / or lignocellulosic fibres. In an embodiment, the three-dimensional fibre network is obtained by a web forming method, typically on a wire, such as by dry forming (dry-laid process), air-laid process or foam forming or any combination thereof, preferably by an air-laid process or by dry forming. Advantages of using a dry-laid process, in particular an air-laid process, are that the obtained fibre network is easy to handle, shows homogeneous fibre distribution, and can be directly obtained in a desired thickness. Air-laying processes also allow for uniform inclusion of dry state additives, such as thermoplastic additives, polymeric fibres, or bicomponent fibres.

[0140] In preferred embodiments of the invention, the cellulosic and / or lignocellulosic fibres 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, 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 fibre network 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. 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.

[0141] In some embodiments of the invention, the step of separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other comprises dry-milling the hydrophobized cellulosic and / or lignocellulosic fibres. The inclusion of a drymilling step, such as a hammer-milling step, in the method provides for a finely separated fibre matrix. The dry-milling 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.

[0142] In some embodiments of the invention, the step of mixing the hydrophobized cellulosic and / or lignocellulosic fibres with a further additive includes the addition of binding agent, such as binding polymers.

[0143] The hydrophobized cellulosic and / or lignocellulosic fibres can be mixed or contacted with binding agent in wet state, such as an aqueous solution or suspension of binding agent. Such binding agent can be mixed with the cellulosic fibres in wet state, such as into wet pulp, or it may be applied through other techniques known in the art, such as by spraying. Wet treatment of fibres is in particular suitable in combination with foam forming techniques. When the three-dimensional fibre network is formed using dryforming techniques, an additional drying step can be employed for cellulosic fibres treated with additives in wet state or solvents.

[0144] The binding agent can additionally or alternatively be applied in dry state, such as by inclusion of binding composition in the form of, for example, particles, fibres, or powder. Inclusion of binding agent, i.e., binding composition, in dry state is preferred especially when using dry -laying techniques, 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.

[0145] The heat treatment step advantageously may remove any excess moisture, and in particular, melt and / or activate any additive. When thermally reactive additives, such as additives comprising thermoplastic polymers are included in the fibre network, the heat treatment can be carried out at a temperature above the melting point or activationpoint 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 or by microwave heating.

[0146] The heat-treatment may be carried out for a period of time in the range 10 seconds to 30 minutes, such as 10 seconds to 5 minutes. For thicker dry-laid structures, such as three-dimensional structures air-laid into a mould, a longer heating period may be advantageous, to achieve expanding of the microspheres and optionally melting of the outer shell of the bicomponent fibres throughout the structure.

[0147] In some embodiments of the present disclosure the step of mixing the hydrophobized cellulosic and / or lignocellulosic fibres with an additive is carried out by adding bicomponent fibres, preferably bicomponent fibres comprising a thermoplastic polymer. The bicomponent fibres can be mixed with the hydrophobized cellulosic and / or lignocellulosic fibres prior to or during the dry-laying step.

[0148] In some embodiments, the dry-laying step produces a sheet or a three- dimensional structure comprising a three-dimensional fibre network comprising the hydrophobized cellulosic and / or lignocellulosic fibres and the microspheres.

[0149] In preferred embodiments of the invention, the step of producing the sheet is carried out using a dry-laying technique, such as an air-laying technique.

[0150] Preferably, said dry laying comprises air laying.

[0151] The dry-laying may be carried out onto a substantially flat substrate, such as onto a wire. When using a wire, the dry-laid mixture is output onto a wire, to obtain a dry- laid sheet, which is subsequently heat-treated.

[0152] Alternatively, the dry-laying may be carried out onto or into a non-flat substrate, such as into a mould. When using a mould, the dry-laid mixture is output, preferably by gravity, into a mould, to fill the mould and to obtain a dry-laid three- dimensional structure, which is subsequently heat-treated. The mould may be perforated, to allow air pass through the mould while retaining the air-laid mixture or materials inside the mould. Advantageously, the mould may be closable, for example to compress the dry-laid structure inside the mould. In an embodiment, the mould may be compressible ortightenable against the dry-laid structure inside the mould. Such compressing action may lead to improved surface smoothness and / or decreasing of porosity.

[0153] In some embodiments, the dry laying is carried out onto a wire, to obtain a dry-laid sheet, or alternatively the dry laying is carried out into a mould, to obtain a dry- laid three-dimensional object.

[0154] As discussed above, dry-laying, such as air-laying techniques allows for the formation of a uniform fibre network with a uniform distribution of the microspheres. 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.

[0155] A preferred embodiment comprises dry-milling the hydrophobized pulp fibres, adding the microspheres, feeding the mixture and an optional dry state additive, preferably bicomponent fibres, to an air-laying process, preferably from separate feed sources, air-laying the mixture and the optional dry state additive into an air-laid structure, and subjecting the air-laid structure to a heat-treatment step.

[0156] 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. At the same time, the heat treatment will lead to expansion of the microspheres.

[0157] Advantageously, when using hydrophobized fibres as the raw material and a dry-laying technique, the microspheres may be effectively retained in within the fibre network. Use of any solvent may be avoided.

[0158] In preferred embodiments, the step of separating the fibres and the step of mixing with the microspheres are carried out in dry state.

[0159] In an embodiment, said hydrophobization step is carried out in wet state, and all subsequent steps of the process are carried out in dry state.

[0160] The microspheres are advantageously fed to the process in unexpanded form. During the process, the microspheres may become physically trapped withing the fibre network, for example already during the dry -milling step or later during the heat-treatment, such as upon melting of bicomponent fibres or other thermally reactive binders present within the fibre network.

[0161] 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 quality fibre network can be obtained in a simplified process, using currently available equipment without the need for retrofitting. The additives may further be melted or activated within the air-laid fibre network, for example by heat treatment.

[0162] In some embodiments, the step of producing the dry-laid structure, such as forming the hydrophobized 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 interaction can be achieved, when compared to dry-formation. Foam forming technology can be used in the formation of three- dimensional fibre network layers in the thickness ranges as disclosed herein.

[0163] In some embodiments, the three-dimensional fibre network is obtained by a foam process carried out on a wire. Such a three-dimensional fibre network can be included in or constitute a cushioning material according to the present disclosure.

[0164] 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.

[0165] In some embodiments, the three-dimensional fibre network is obtained by continuous web forming or by mould-assisted forming.

[0166] Such a foam formed three-dimensional fibre network can be included in or constitute a product according to the present disclosure.

[0167] Example 1

[0168] In the following we describe an exemplary process for manufacturing the present product.

[0169] In an embodiment, the components of the product are hydrophobized pulp fibres in an amount of 50 to 85 wt-%; thermoplastic thermally expanded microspheres in an amount of 0.5 to 30 wt-%, such as 10 to 30 wt-%; and thermoplastic bicomponent fibres in an amount of 1 to 30 wt-%, such as 5 to 20 wt-%, such as 7 to 14 wt-%. The thermally expanded microspheres may act as thermoplastic binders. The pulp, for example in the form of dry bale pulp, can be hydrophobized with for example AKD, in an amount 0.5 to 5 wt-% by weight of dry pulp fibres. Then, the pulp fibres are hammer-milled into loose fibrous fluff. The hammer-milled pulp fibres, bicomponent fibres and thermoplastic thermally expandable microspheres are then fed as a mixture into an air-laid line. The mixture is air-laid into a sheet and heat treated in an oven at 165 °C for 2 min. During the heat-treatment the thermoplastic thermally expandable microspheres expand and fill cavities between the pulp fibres. Despite consisting mostly of pulp fibres, the resulting product is rubber-like. Without being bound to any theory, even though the mass share of the thermoplastic thermally expanded microspheres is relatively low, their properties may dominate the overall product properties, and this may be due to their hollow and bouncy nature.

[0170] Example 2

[0171] Analysis of hydrophobized fibres

[0172] Laboratory-scale hand sheets were manufactured from hydrophobized pulp (1 wt-% AKD) and non-hydrophobized pulp (reference) by the method according to ISO535:2023 (modified). The grammage of the hand sheet was 72.6 g / m2 for non- hydrophobized pulp and 76.4 g / m2for hydrophobized pulp (according to ISO 5270:2022).

[0173] For the hand sheet prepared from non-hydrophobized pulp, water contact angle was 14.1°.

[0174] For the hand sheet prepared from hydrophobized pulp, water contact angle was 135.3°.

[0175] Analysis of sample products

[0176] Properties of three samples (A, B, C) comprising hydrophobized pulp, bicomponent fibres and thermally expanded microsphered were determined.

[0177] SamplesSample A: hydrophobized kraft pulp (1 wt-% AKD), 14 wt-% bicomponent fibres (AL Adhesion-C), and 30 wt-% thermally expandable microspheres (Expancel 043DU80 by Nouryon). Heat treatment at 165 °C, 2 min. Density 30.9 kg / m3.Sample B: hydrophobized kraft pulp (1 wt-% AKD), 10 wt-% bicomponent fibres (AL Adhesion-C), and 20 wt-% thermally expandable microspheres (Expancel 043DU80). Heat treatment at 165 °C, 2 min. Density 33.6 kg / m3.Sample C: hydrophobized kraft pulp (1 wt-% AKD), 7 wt-% bicomponent fibres (AL Adhesion-C), and 15 wt-% thermally expandable microspheres (Expancel 043DU80). Heat treatment at 165 °C, 2 min. Density 37.9 kg / m3.

[0178] The dimensions of the samples were 400 mm x 400 mm x respective thickness.

[0179] Hardness index was determined according to SFS-EN ISO 2439 Flexible cellular polymeric materials - Determination of hardness (indentation technique) (ISO 2439:2008): 7.3 Method A — Determination of the 40 % / 30 s indentation hardness index.

[0180] Hardness index H is defined as the force (N) with which the material becomes compressed by 40% from its original thickness, when pressing with a measurement probe having a diameter of 200 mm.

[0181] Fatigue was determined according to SFS-EN ISO 3385 Flexible cellular polymeric materials - Determination of fatigue by constant-load pounding (ISO 3385:2014), a dynamic test of 80 000 cycles (device type B), force 750 N, 60 times per second, a measurement probe having a diameter of 250 mm. Thickness was measured at 10 000 cycle intervals.

[0182] Table 1 : Sample A.

[0183] Table 2: Sample B.

[0184] Table 3: Sample C.

[0185] The results show that when the amount of bicomponent fibres and thermally expanded microspheres is high, the indentation hardness and the change in indentation hardness increase. When the amount of bicomponent fibres and thermally expanded microspheres is low, the indentation hardness and the change in indentation hardness decrease. The results show that when the amount of bicomponent fibres and thermally expanded microspheres is high, indentation hardness is higher compared to when the amount of bicomponent fibres and thermally expanded microspheres is low. Change in indentation hardness is lowest when the amount of bicomponent fibres and thermallyexpanded microspheres is high.

[0186] Advantageously, by applying different amounts and combinations of fibres, microspheres and additives, a large range of different products may be produced, for different applications.

[0187] FIGURE 1 shows graphically the thickness of Samples A (uppermost graph), B (middle graph) and C (lowermost graph) as a function of cycles.

[0188] FIGURE 2 is a microscope image of a product manufactured according an embodiment of the present invention. The product comprised hydrophobized kraft pulp (1 wt-% AKD), 14 wt-% bicomponent fibres (AL Adhesion-C), and 30 wt-% thermally expanded microspheres (Expancel 043DU80). Heat treatment at 165 °C, 2 min.

[0189] FIGURE 3 is a microscope image of a product manufactured according an embodiment of the present invention. The product comprised hydrophobized kraft pulp (1 wt-% AKD), and 30 wt-% thermally expanded microspheres (Expancel 043DU80). The product did not comprise any bicomponent fibres. Heat treatment at 165 °C, 2 min.

[0190] FIGURE 4 is a microscope image of a product manufactured according an embodiment of the present invention. The product comprised hydrophobized kraft pulp (1 wt-% AKD), 20 wt-% bicomponent fibres (AL Adhesion-C), and 30 wt-% thermally expanded microspheres (Expancel 043DU80). Heat treatment at 165 °C, 2 min.

[0191] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0192] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0193] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However,these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0194] 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.

[0195] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0196] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY

[0197] The present products are industrially applicable at least in manufacturing of fibrous light-weight materials.ACRONYMS LISTAKD alkyl ketene dimer

Claims

CLAIMS:

1. A product comprising:- a three-dimensional fibre network of cellulosic and / or lignocellulosic fibres, and- thermally expanded microspheres, wherein the cellulosic and / or lignocellulosic fibres have been treated with a hydrophobization agent.

2. The product according to any of the preceding claims, wherein the thermally expanded microspheres comprise hollow thermally expanded microspheres, such as flexible hollow thermally expanded microspheres.

3. The product according to any of the preceding claims, wherein the thermally expanded microspheres comprise a polymer shell that encapsulates a volume of a gas.

4. The product according to any of the preceding claims, wherein the thickness of the polymer shell of the thermally expanded microspheres is in the range 0.01 to 1 pm.

5. The product according to any of the preceding claims, wherein the average particle size (D50) of the thermally expanded microspheres is in the range 5 to 100 pm, such as 20 to 100 pm.

6. The product according to any of the preceding claims, wherein the thermally expanded microspheres are distributed throughout the three-dimensional fibre network, preferably substantially uniformly.

7. The product according to any of the preceding claims, wherein the product comprises at least 50 wt-%, such as at least 60 wt-% of cellulosic and / or lignocellulosic fibres, calculated of the dry weight of the product.

8. The product according to any of the preceding claims, wherein the product comprises at least 0.1 wt-%, such as at least 0.5 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, or 1 to 30 wt-% of thermally expanded microspheres.

9. The product according to any of the preceding claims, wherein the product comprises at least 0.1 vol-%, such as at least 1 vol-% of thermally expanded microspheres, calculated of the total volume of the product.

10. The product according to any of the preceding claims, wherein the polymer shell of the thermally expanded microspheres comprises or consists of a thermoplastic polymer, such as a thermoplastic copolymer based on acrylic monomers.

11. The product according to any of the preceding claims, wherein the thermally expanded microspheres or the polymer shell thereof act as a binding agent.

12. The product according to any of the preceding claims, wherein the hydrophobization agent is selected from the following group: fatty acids, rosins, waxes, such as alkyl ketene dimer (AKD) or paraffin wax, oils, such as alkenyl succinic anhydride (ASA), fatty alcohols, fatty acid esters, biopolymers, cationic polyamines, cationic polyethyleneimines (PEI), cationic or non-ionic polyacrylamides, polydimethyldiallylammonium chloride (pDADMAC), maleic anhydride (MA), maleic anhydride grafted polypropylene (MAPP), silanes, alkoxysilanes, organosilanes, betulin, betulinic acid, and derivatives and combinations thereof.

13. The product according to any of the preceding claims, wherein the hydrophobization agent is alkyl ketene dimer (AKD) or a wax.

14. The product according to any of the preceding claims, wherein the product comprises bicomponent fibres.

15. The product according to any of the preceding claims, wherein the product comprises at least 0.1 wt-%, such as at least 1 wt-%, such as at least 5 wt-%, such as at least 10 wt-%, such as 10 to 30 wt-% of bicomponent fibres, calculated of the dry weight of the product.

16. The product according to any of the preceding claims, wherein the density of the product is in the range of 20 to 250 kg / m3, such as 20-90 kg / m3.

17. The product according to any of the preceding claims, wherein the cellulosic and / or lignocellulosic fibres originate from wood, such as from chemical or mechanical wood pulp.

18. The product according to any of the preceding claims, wherein the product is in the form of a sheet or a slab, such as a rollable sheet or a rollable slab, or in the form of a three-dimensional object, such as a spherical or conical object.

19. The product according to any of the preceding claims, wherein the product has been obtained by using an air-laid process or a foam forming process.

20. The product according to any of the preceding claims, wherein the product comprises at least 5 wt-% of thermally expanded microspheres, and bicomponent fibres, and wherein the thermally expanded microspheres are distributed throughout the three-dimensional fibre network.

21. The product according to any of the preceding claims, wherein the product is a monolayer product.

22. The product according to any of the preceding claims, wherein the thermally expanded microspheres and the bicomponent fibres are distributed throughout the three-dimensional fibre network, substantially uniformly.

23. The product according to any of the preceding claims, wherein the product has an indentation hardness in the range of 50 to 2000 N, such as 150-1400 N, when determined as 40 % / 30 s indentation hardness index according to ISO 2439:2008, Method A.

24. The product according to any of the preceding claims, wherein the thickness of the product is 1-150 mm.

25. A method comprising the steps of:- providing a pulp composition comprising cellulosic and / or lignocellulosic fibres;- mixing the pulp composition with at least one hydrophobization agent to produce hydrophobized cellulosic and / or lignocellulosic fibres;- at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other;- mixing the hydrophobized cellulosic and / or lignocellulosic fibres with thermally expandable or expanded microspheres;- dry-laying the mixture, to obtain a dry-laid structure; and- heat-treating the dry-laid structure.

26. The method according to claim 25, wherein the step of mixing the pulp composition with at least one hydrophobization agent is carried out at a consistency of 10 to 40%, such as 10 to 30% of the pulp composition.

27. The method according to any of claims 25 to 26, wherein said separating step comprises at least partially separating the hydrophobized cellulosic and / or lignocellulosic fibres from each other in a dry state by using a hammer mill.

28. The method according to any of claims 25 to 27, wherein said separating step leads to separation of fibres and loosening of inter-fibre bonds in the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to obtain a loose fibrous fluff.

29. The method according to any of claims 25 to 28 wherein said separating step comprises debundling the hydrophobized cellulosic and / or lignocellulosic fibres.

30. The method according to any of claims 25 to 29, further comprising: after the separating step, mixing the hydrophobized cellulosic and / or lignocellulosic fibres with bicomponent fibres.

31. The method according to any of claims 25 to 30, comprising: between said mixing step with at least one hydrophobization agent and said separating step, drying the hydrophobized cellulosic and / or lignocellulosic fibres, preferably to a moisture content less than 15 wt-%.

31. The method according to any of claims 25 to 30, wherein said dry laying comprises air laying.

32. The method according to any of claims 25 to 31, wherein the thermally expandable microspheres comprise a polymer shell that encapsulates a volume of a gas or a liquid, preferably a volume of a gas.

33. The method according to any of claims 25 to 32, wherein the thermally expandable microspheres are capable of expanding at least 2 times their original volume upon being heated to a temperature in which the encapsulated gas expands or the encapsulated liquid vaporizes.

34. The method according to any of claims 25 to 33, wherein said heat treating leads to an increase of the volume of the thermally expandable microspheres to at least 2 times, such as at least 10 times, such as at least 20 times their original volume.

35. The method according to any of claims 25 to 34, wherein said heat treating leads to softening of a polymer shell of the thermally expandable microspheres and / or softening of an outer shell of the bicomponent fibres, preferably to bind the cellulosic and / or lignocellulosic fibres together.

36. The method according to any of claims 25 to 35, wherein the melting temperature of the outer shell of the bicomponent fibres is lower than the melting temperature of the polymer shell of the thermally expandable microspheres.

37. The method according to any of claims 25 to 3236 wherein the heat treatment is carried out in a temperature in the range of 80 to 250 °C, such as 100 to 230 °C.

38. The method according to any of claims 25 to 37, wherein the heat treatment is carried out in a temperature that is between the melting temperature of the outer shell of the bicomponent fibres and the melting temperature of the polymer shell of the thermally expandable microspheres.

39. The method according to any of claims 25 to 38, wherein the heat treatment is carried out in a temperature that is above the melting temperature of the outer shell of the bicomponent fibres, such as above 120 °C.

40. The method according to any of claims 25 to 39, wherein the heat treatment is carried out in a temperature that is below the melting temperature of the polymer shell of the thermally expandable microspheres, such as below 250 °C.

41. The method according to any of claims 25 to 40, wherein the heat treatment comprises pressing or calendering the dry -laid structure.

42. The method according to any of claims 25 to 41, wherein said mixing step with at least one hydrophobization agent is carried out in wet state, and the subsequent steps of the process are carried out in dry state.

43. The method according to any of claims 25 to 42, wherein the dry laying is carried out onto a wire, to obtain a dry-laid sheet, or the dry laying is carried out into a mould, to obtain a dry-laid three-dimensional object.

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