Method for manufacturing a fiber-based industrial material, fiber-based industrial material and apparatus for manufacturing a fiber-based industrial material

Abstract

The present disclosure concerns a method for manufacturing a fiber-based industrial material, in particular by preparing and forming a fibrous foam into a foam layer, a fiber-based industrial material, and an apparatus for manufacturing a fiber- based industrial material.

Description

[0001]METHOD FOR MANUFACTURING A FIBER-BASED INDUSTRIAL MATERIAL, FIBER-BASED INDUSTRIAL MATERIAL AND APPARATUS FOR MANUFACTURING A FIBER-BASED INDUSTRIAL MATERIAL The present disclosure concerns a method for manufacturing a fiber-based industrial material, in particular by preparing and forming a fibrous foam into a foam layer, a fiber-based industrial material, and an apparatus for manufacturing a fiber- based industrial material. TECHNICAL BACKGROUND Fiber-based industrial materials are widely used in modern society and have many applications, such as packaging, paperboard, filtration, thermoformable composites, technical composites, and abrasive paper materials. These materials are usually manufactured by a conventional wet process, which consists of preparing an aqueous slurry of fibers (pulp slurry), feeding the slurry to a headbox that spreads the slurry on a wire that allows the liquid to drain through while retaining most of the fibers in the form of a continuous web, pressing, and drying to manufacture finished products. These materials may also be manufactured by molding an aqueous pulp slurry, pressing, and drying. The main physical properties of these materials are, e.g., basis weight, density, thickness, strength (compression, z-directional and bending strength), stiffness, insulation, and resistance to lint and dust. While the above process can produce materials with distinctive properties, it has been difficult to achieve lightweight materials with good formation. Furthermore, the manufacturing process still requires large amounts of water and energy and finding more sustainable / environment friendly production methods would, hence, be desirable. An alternative production method may rely on foam forming. However, the foam forming process can be relatively slow, thus limiting production efficiency and capacity. Moreover, it has proven difficult to achieve high quality materials with high consistency when relying on foam forming techniques. The present disclosure aims at addressing one or more of the above shortcomings. In one aspect, it is an object of the present disclosure to provide a raw material and / or energy efficient process for manufacturing a fiber-based industrial material. A further object is to provide an apparatus for manufacturing a fiber-based industrial material. Further objects will become apparent from the following detailed description. SUMMARY OF THE PRESENT DISCLOSURE The present disclosure provides a raw material and / or energy efficient process for manufacturing a fiber-based industrial material. In particular, the present disclosure relates to a method of manufacturing a fiber-based industrial material including the steps of: - preparing a fibrous foam, wherein the preparing comprises dispersing solids and one or more surface active agents in a liquid and / or a foam, with a solids content of 5% to 60% by weight, at least 50% by weight of the solids are fibers, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content of 40% to 95% by weight, and supplying and dispersing gas in the liquid and / or the foam until a gas content of 64% or more by volume is reached; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet, wherein the fibrous web or sheet has a liquid content of 20% to 85% by weight; and -drying the fibrous web or sheet to obtain a fiber-basedindustrial material. More generally, the foam may be prepared first and the dispersing of solids and of gas in the foam may then be performed. Alternatively, the foam may be prepared, and solids may be dispersed in the liquid and in the foam. Alternatively, the solids may be dispersed in the liquid. In each of these scenarios, the solids may comprise or consist of fibers. Regarding the preparing, the fiber content may be 5% to 60% by weight, 8% to 60% by weight, 10% to 60% by weight, 12% to 60% by weight, or 14% to 60% by weight, 15% to 60% by weight, or 15% to 55% by weight, 15% to 50% by weight or 15% to 45% by weight, or 15% to 40% by weight, or 15% to 35% by weight, or 15% to 30% by weight; the gas content may be 70% or more by volume, or 75%, or 80%, or 85%, or 90% or more by volume; the surface active agents content may be 0.02% to 1.1% by weight, or 0.02% to 1.0% by weight, or 0.05% to 0.8% by weight; and the liquid content may be 53.9% to 91.8% by weight, or 65% to 85% by weight, or 78.9% to 89.95% by weight. More generally, the liquid content may be 100% minus the sum of the surface active agents content and the fiber content. Optionally, the liquid content may be slightly lower, and the further content of a gas-dispersed liquid may be referred to as the remainder. The remainder may, e.g., be from 0% to 3% by weight, or 0% to 2% by weight, or 0% to 1%, 0.8%, 0.5%. The present disclosure also relates to a method of manufacturing a fiber-based industrial material including the steps of: -preparing a fibrous foam by supplying fibers and one ormore surface active agents to a liquid and / or a foamand dispersing gas in the liquid and / or the foam, thereby reaching a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet; and- drying the fibrous web or sheet to obtain a fiber-basedindustrial material. More generally, the foam may be prepared first and the dispersing of solids and of gas in the foam may then be performed. Alternatively, the foam may be prepared, and solids may be dispersed in the liquid and in the foam. Alternatively, the solids may be dispersed in the liquid. In each of these scenarios, the solids may comprise or consist of fibers. In one aspect, the present disclosure provides a fiber-based industrial material having excellent properties, especially one or more of an excellent basis weight, density, strength, and / or thermal insulation. In particular, the present disclosure relates to a fiber-based industrial material that is manufacturable by the above methods. The present disclosure also relates to a fiber-based industrial material comprising at least 50 wt.-% of fiber material based on the total weight of the fiber-based industrial material, wherein the fiber-based industrial material has a basis weight of 50 to800 g / m and a density of 200 to 1200 kg / m, and wherein avariation σ of the basis weight measured in accordance with SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product. In one aspect, the present disclosure provides an apparatus for manufacturing a fiber-based industrial material. In particular, the present disclosure relates to an apparatus for manufacturing a fiber-based industrial material comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means comprises a supply means that supplies solids, one or more surface active agents, a liquid, and gas, wherein a solids content is 5% to 60% by weight, at least 50% by weight of the solids are fibers, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume. The present disclosure also relates to an apparatus for manufacturing a fiber-based industrial material comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - optionally a draining means draining the fibrous a further processing means, such as a draining means, further processing the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means prepares the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less. In particular, the present disclosure relates to the following embodiments (items): 1. A method of manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material, the method including the steps of: -preparing a fibrous foam, wherein the preparingcomprises dispersing solids and one or more surface active agents in a liquid and / or a foam, with a solids content of 5% to 60% by weight, wherein at least 50% by weight of the solids are fibers, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content is 40% to 95% by weight, and supplying and dispersing gas in the liquid and / or the foam until agas content of 64% or more by volume is reached; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet, wherein the fibrous web or sheet has a liquid content of 20% to 85% by weight; and -drying the fibrous web or sheet to obtain a fiber-basedindustrial material. 2. The method of item 1, wherein the dispersing of the gas in the liquid and / or the foam is performed using a feedback loop control, optionally including measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value. 3. The method of item 1 or 2, wherein the preparing comprises supplying the gas and the liquid into a vessel such that a ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value, and mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and / or a gas content reaches a predetermined minimum threshold. 4. The method of any one of the preceding items, wherein the liquid comprises at least 80% by weight of water, and / or the gas used to prepare the fibrous foam comprises at least 95% air by volume. 5. The method of any one of the preceding items, wherein the fibrous foam comprises a liquid with at least 80% by weight of water, and / or a gas with at least 95% air by volume. 6. A method of manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material,the method including the steps of: -preparing a fibrous foam, wherein the preparingcomprises dispersing solids and one or more surface active agents in a liquid and / or a foam, wherein at least 50% by weight of the solids are fibers, and supplying and dispersing gas in the liquid and / or the foam, thereby reaching a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet; and -drying the fibrous web or sheet to obtain a fiber-basedindustrial material. 7. The method of any one or the preceding items, wherein the fibrous foam in the foam layer is drained to form the fibrous web or sheet with a solids content of 15% to 80% by weight, wherein, optionally, the foam layer prior to draining has a solids content in a range of from 5% to 60%. 8. The method of any one of the preceding items, wherein the dispersing of the gas in the liquid is performed using a feedback loop control, optionally including measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value. The method of any one of the preceding items, wherein the preparing comprises supplying the gas and the liquid into a vessel such that a ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value, and mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and / or a gas content reaches a predetermined minimum threshold. The method of any one of the preceding items, wherein the liquid comprises at least 80% by weight of water, and / or wherein the gas comprises at least 95% air by volume. The method of any one of the preceding items, wherein a gas content is 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume. The method of any one of the preceding items, wherein the fibrous foam comprises a liquid with at least 80% by weight of water, and / or a gas with at least 95% air by volume. The method of any one of the preceding items, wherein the preparing comprises processing dry fibers or solids, moisturized fibers or solids, a liquid slurry, or a foam, and fibers into the fibrous foam. The method of item 13, wherein the processing is at least partially performed by a transporting means that transports the fibrous foam to a forming means that forms the fibrous foam into the foam layer. The method of item 14, wherein the processing is performed by the transporting means. 16. The method of items 7 and 14 or 7 and 15, wherein the processing is performed by a processing means and the draining of the fibrous foam is performed by a draining means, wherein, optionally, one or several of the following components are part of one integral structural unit: the preparation means, the processing means, the transporting means, the forming means, and the draining means, wherein, optionally, the processing means comprises the transporting means. 17. The method of any one of items 14 to 16, wherein the processing comprises increasing a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar, and, optionally, 10 bars or less. 18. The method of any item 17, wherein the increasing of the pressure comprises successively applying a plurality of different pressure levels in the downstream direction, wherein the pressure level is optionally decreased twice or more and / or the pressure level is optionally increased twice or more. 19. The method of any one of items 14 to 18, wherein the processing and / or transporting comprises at least one of: shear, elongational and / or distributive mixing,defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives. 20. The method of any one of the preceding items, wherein the preparing comprises supplying a rheology modifier. 21. The method of any one of the preceding items, wherein the draining of the fibrous foam comprises, optionally, consists of suction and / or mechanical draining such as pressing. The method of any one of the preceding items, wherein the fiber-based industrial material has a liquid content of 0.5% to 15% by weight, optionally, 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight, wherein, optionally, the fiber-based industrial product has a water content of 0.5% to 10% by weight, optionally, 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight. The method of any one of the preceding items, wherein the prepared fibrous foam has a solids content of more than 10% by weight, optionally a fiber content of more than 10% by weight. The method of any one of the preceding items, wherein the forming of the fibrous foam into a foam layer comprises bringing the fibrous foam into a planar form. The method of any one of the preceding items, comprising bringing a liquid slurry, a foam, optionally the fibrous foam, into contact with at least one rotatable means and rotating the at least one rotatable means to transport and / or to process the foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute. The method of item 25, wherein the rotating of the at least one rotatable means promotes defiberizing and / or deflocculating at least a part of the fibers, optionally, all of the fibers. The method of item 25 or 26, wherein the liquid slurry, the foam, optionally the fibrous foam, is transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin- screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means. The method of any one of items 25 to 27, wherein the rotatable means is housed by a housing and a minimum distance between the rotatable means and the housing during rotation is in the range of 0.2 to 20% of a diameter of the at least one screw, and, optionally, in the range of from 0.3 mm to 20 mm. The method of any one of items 25 to 28, wherein the rotating of the at least one rotatable means promotes at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and heating. The method of any one of items 25 to 29, wherein the liquid slurry, and / or the foam, and / or the fibrous foam is generated in and / or transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple- screw machine, a conical screw mixer, comprising the at least one rotatable means. The method of any one of items 25 to 30, wherein the rotatable means is housed by a housing and a minimum distance between the rotatable means and the housing during rotation is in the range of from 0.3 mm to 20 mm. The method of item 30, comprising supplying, to the liquid slurry, and / or the foam, and / or the fibrous foam, when transporting it through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and / or a liquid slurry; and - a solid, such as fibers, powder, and / or granulate. 33. The method of any one of items 25 to 32, wherein the rotating of the at least one rotatable means comprises rotating a twin-screw, a single-screw, or a multiple-screw, and the transporting the fibrous foam by rotating the at least one rotatable means comprises one or several of the following: accelerating the fibrous foam; decelerating the fibrous foam; applying a shear and / or elongation force to the fibrous foam. 34. The method of any one of items 25 to 33, wherein the rotating of the at least one screw is performed in a screw assembly, such as an extruder or a screw mixer, the screw assembly comprises a housing and the at least one screw, wherein a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 0.2% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm. 35. The method of any one of items 25 to 34, wherein the at least one rotatable means comprises at least a first screw and a second screw, and a distance of closest approach between the first screw and the second screw during rotations is in the range of from 0.3 mm to 20 mm. 36. The method of any one of items 25 to 35, wherein the at least one rotatable means comprises a plurality of screws and at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm. 37. The method of item 7 or any item dependent on item 7, wherein the fibrous foam is displaced, prior to the forming, by a displacement pump, optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, or a flexible impeller pump. The method of item 7 or any item dependent on item 7, wherein the draining comprises applying a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation. The method of item 7 or any item dependent on item 7, wherein the draining is performed by successively applying at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure. The method of any one of the preceding items, wherein the forming of the fibrous foam into the foam layer is at least in part performed in a die and / or a headbox and / or a cylindrical mold former and / or a suction breast roll former, and / or wherein the processing and / or the forming of the foam layer is performed in a controlled pressure chamber. The method of item 40, wherein the die is a slot die with an adjustable die gap, wherein the fibrous foam is processed into a continuous fibrous web or sheet on a moving continuous dewatering / conveyor unit. The method of any one of the preceding items, comprising, prior to the step of preparing the fibrous foam, a step of preparing a slurry comprising at least one component selected from the group consisting of: water, fibers, a surface active agent, a binder, and a slipping agent; wherein the preparing of the slurry is optionally at least partially performed in a high consistency mixing apparatus. 43. The method of any one of the preceding items, wherein the drying is thermal, freeze, infrared, contact, microwave, impingement, or through air drying. 44. The method of any one of the preceding items, wherein the preparing of the fibrous foam comprises supplying at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, zwitterionic surface active agents, amphoteric surface active agents, and nonionic surface active agents. 45. The method of any one of the preceding items, wherein the preparing of the fibrous foam comprises supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent, the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, and sucrose esters. 465. The method of item 454, wherein the at least one nonionic surface active agent is selected from the group consisting of alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols, the at least one nonionic surface active agent being optionally an alkylpolyglucoside of the general formula (1): R1-O-(R2)n-H (1)wherein, R1is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R2is a hexose or pentose unit, n is 1 to 5. The method of any one of the preceding items, wherein the preparing of the fibrous foam comprises pre-moisturizing the fibers and mixing, optionally with a paddle mixer, until a solids content in the range of 30% to 50% by weight is reached, to form pre-moistened fibers, the solids content being based on the total weight of the pre-moistened fibers. The method of item 47, as dependent on item 13, wherein the pre-moistened fibers are conveyed and fed to the processing means, wherein the feeding is optionally performed using a volumetric and / or gravimetric feeder. The method of any one of the preceding items, wherein the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means is promoted by the same mechanical movement. A fiber-based industrial material that is manufacturable by the method according to any one of the preceding items. The fiber-based industrial material of item 50, wherein the fiber-based material has a basis weight of 50 to 800 g / mand a density of 200 to 1200 kg / m and / or wherein a variationσ of the basis weight measured in accordance with SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product. A fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasivepaper material, comprising at least 50 wt.-% of fibers based on the total weight of the fiber-based material, wherein the fiber-based material has a basis weight of50 to 800 g / m and a density of 200 to 1200 kg / m, and whereina variation σ of the basis weight measured in accordancewith SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product. 53. The fiber-based industrial material of any one of items 50 to 52, comprising a surface active agent. 54. The fiber-based industrial material of item 52 or 53, wherein the fiber-based material has an upper side and a lower side, and a density in a central region of the fiber- based material located between the upper and lower sides in a thickness direction is lower than a density in a region of the fiber-based material located at the lower and / or upper side(s). 55. The fiber-based industrial material of any one of items 52 to 54, which comprises one or more of the following (a) to (e): (a) at least 0.5 wt.-% of one or more binders, (b) at least 0.05 wt.-% of one or more rheology modifiers, (c) at least 0.01 wt.-% of one or more surface active agents, (d) at least 0.2 wt.-% of one or more slipping agents, and (e) at least 0.5 wt.-% of one or more fillers, each based on the total weight of the fiber-based material. 56. An apparatus for manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material,comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means comprises a supply means that supplies solids, one or more surface active agents, a liquid, and gas, wherein a solids content is 5% to 60% by weight, and wherein at least 50% by weight of the solids are fibers, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume. 57. The apparatus of item 56, wherein the supply means supplies liquid and / or a foam, in which the surface active agents, the fibers, and the gas are dispersed, comprising at least 85% by weight of water, and / or gas being dispersed in the liquid and / or the foam comprising at least 95% air by volume. 58. The apparatus of item 56 or 57, wherein the fibrous foam preparation means prepares a gas-liquid dispersion that comprises a liquid content of at least 85% by weight of water, and / or a gas content of at least 95% air by volume. 59. An apparatus for manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material,comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means prepares the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less. 60. The apparatus of item 59, wherein the fibrous foam preparation means prepares the fibrous foam with a solids content, wherein a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content is the fiber content. 61. The apparatus of item 59 or 60, wherein a solids content is 5% to 60% by weight, at least 50% by weight of the solids are fibers, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, or at least 85%, or at least 90%, by volume. 62. The apparatus of any one of items 56 to 61, wherein the fibrous foam preparation means comprises a processing means that processes a liquid slurry or a foam, and solids into the fibrous foam. 63. The apparatus of item 62, wherein the processing means comprises a transporting means that transports the liquid slurry, and / or the foam, and / or the fibrous foam to the foam layer formation means, wherein, optionally, the transporting means performs at least a part of the processing, wherein, optionally, the transporting means performs the processing. 64. The apparatus of item 63, wherein the apparatus supplies the fibrous foam prepared by the fibrous foam preparation means to the transporting means. 65. The apparatus of item 63, wherein the transporting means performs at least a part of the processing, wherein, optionally, the transporting means performs the processing. 66. The apparatus of any one of items 56 to 65, wherein the fibrous foam preparation means transports the fibrous foam to the fibrous foam formation means. 67. The apparatus of any one of items 56 to 66, wherein the fibrous foam preparation means promotes the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means by the same mechanical movement, and / or wherein the fibrous foam preparation means transports the fibrous foam to the forming means. 68. The apparatus of any one of items 56 to 67, wherein one or several of the following components are part of one integral structural unit: the processing means, the fibrous foam preparation means, the transporting means, the forming means, and the draining means. 69. The apparatus of item 63 or an item dependent on item 63, wherein the transporting means comprises a pressurization section that increases a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar and, optionally, 10 bars or less. 70. The apparatus of item 69, wherein the pressurization section successively applies a plurality of different pressure levels in the downstream direction, the pressure being increased at least twice and / or decreased at least twice. 71. The apparatus of any one of items 56 to 70, wherein the processing means performs at least one of the following: shear, elongational, and / or distributive mixing,defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives. 72. The apparatus of any one of items 56 to 71, the apparatus further comprising one or several solids supply means supplying solids to the fibrous foam preparation means, and one or several liquid supply means supplying liquid to the fibrous foam preparation means, to form the fibrous foam with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam. 73. The apparatus of any one of items 56 to 72, wherein the fibrous foam preparation means comprises a rheology modifier supply means that supplies a rheology modifier. 74. The apparatus of any one of items 56 to 73, wherein the draining means is a mechanical draining means. 75. The apparatus of any one of items 56 to 74, wherein the fibrous foam preparation means prepares the fibrous foam to have a solids content of more than 10% by weight, optionally a fiber content of more than 10% by weight. 76. The apparatus of any one of items 56 to 75, wherein the fibrous foam formation means brings the fibrous foam into a planar form. 77. The apparatus of any one of items 56 to 76, comprising at least one rotatable means, the apparatus bringing the fibrous foam into contact with the at least one rotatable means and rotating the at least one rotatable means to transport the fibrous foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute. The apparatus of item 77, wherein the rotating of the at least one rotatable means promotes at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and heating, transporting, exerting pressure on, and building up pressure on the fibrous foam. The apparatus of item 77 or 78, comprising at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple- screw machine, a conical screw mixer, comprising the at least one rotatable means. The apparatus of any one of items 77 to 79, comprising a housing that houses the rotatable means, wherein a minimum distance between the rotatable means and an opposing inner surface of the housing is in the range of 0.2 to 20% of a diameter of the at least one rotatable means, and, optionally, in the range of 0.3 to 20 mm. The apparatus of item 79 or 80, comprising a supply means supplying, while the fibrous foam is prepared and / or processed and / or transported through the extruder, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and / or a liquid slurry; and - a solid, such as fibers, powder and / or granulate. The apparatus of any one of items 77 to 81, wherein the at least one rotatable means is a twin-screw, a single-screw, or a multiple-screw, and the at least one rotatable means optionally comprises one or several of the following sections: an acceleration section that accelerates the fibrous foam being transported through the processing device; a deceleration section that decelerates the fibrous foam being transported through the processing device; a shear and / or elongation application section that applies a shear and / or elongation force to the fibrous foam. The apparatus of any one of items 77 to 82, comprising a screw assembly that comprises a housing and the at least one screw, wherein a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 0.2% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm The apparatus of any one of items 77 to 83, wherein the at least one rotatable means comprises at least a first screw and a second screw, and a distance of closest approach between the first screw and the second screw during rotations is in the range of from 0.3 mm to 20 mm. The apparatus of items 77 to 84, wherein the at least one rotatable means comprises a plurality of screws and at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm. The apparatus of any one of items 56 to 85, comprising a displacement pump, optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, that, prior to the forming, displaces the fibrous foam. 87. The apparatus of any one of items 56 to 86, wherein the draining means applies a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation. 88. The apparatus of any one of items 56 to 87, wherein the draining means successively applies at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure. 89. The apparatus of any one of items 56 to 88, wherein the foam layer formation means comprises a die and / or a headbox and / or a cylindrical mold former and / or a suction breast roll former. 90. The apparatus of item 62 or an item dependent on item 62, wherein the processing means and / or the foam layer formation means are provided in a controlled pressure chamber. 91. The apparatus of any one of items 56 to 90, comprising a slurry preparation device that prepares an intermediate mixture / slurry foam / slurry solution comprising at least one component selected from the group consisting of: water, fibers, one or more surface active agents, one or more binders, and one or more slipping agents; the slurry preparation device optionally comprising in a high consistency mixing apparatus. 92. The apparatus of any one of items 56 to 91, wherein the drying means is a thermal, freeze, infrared, microwave, contact, impingement, or through air drying means. 93. The apparatus of any one of items 56 to 92, comprising a surface active agent supply means that supplies at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents. 94. The apparatus of any one of items 56 to 93, comprising a temperature control means that controls a temperature inside at least one section of the apparatus. 95. The apparatus of any one of items 56 to 94, comprising a control device that controls the apparatus to perform the method of any one of items 1 to 49. 96. Use of the apparatus of any one of items 56 to 95 for manufacturing a fiber-based industrial product. DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE 1. Definitions The term “fiber-based industrial material” as used herein refers to a material having a web-like structure containing fibers and optionally other additives. In this context, the term “fiber- based” refers to a structure in which individual fibers lie interlaid. In some aspects, the term “fiber-based industrial material” refers to a material having a basis weight of 50 to 800 g / m and a density of 200 to 1200 kg / m. In this context, the term “industrial material” as used herein refers to a fiber-based material with industrial applications, such as packaging, filtration, construction, or the like. The industrial material may be, e.g., a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material. The term “industrial material” as used herein does not encompass products in the following categories: - incontinence care: e.g., incontinence pants, panty liners, pads, leakproof apparels, cleansing wipes and creams, wash gloves, washable underwear (i.e., absorbent underwear for menstruation and incontinence), etc.; - feminine care: e.g., pads, panty liners, tampons, intimate soaps, intimate wipes, leakproof apparels, washable underwear (i.e., absorbent underwear for menstruation and incontinence), menstrual cups, etc.; - baby care: e.g., baby diapers, pant diapers, wet wipes, shampoo, lotion, baby oil, etc.; - beauty care: e.g., cotton products for make-up removal, face lotions, wet wipes, hand soaps, hand lotions, etc.; - paper / fiber-based and composite material-based products, including, but not limited, to products and materials made of tissue, non-woven and specialty papers, in the following two application fields: (i) Personal hygiene, e.g. toilet paper, facial tissues, handkerchiefs, napkins, wet wipes, cloths, paper towels, household towels / kitchen towels, and (ii) Wiping, e.g. object wiping such as paper towels, household towels / kitchen towels, napkins, wet wipes, cloths and wipers for cleaning, wiping, polishing and / or disinfecting surfaces; - soap & sanitizers: e.g., soaps, lotions, sanitizers, etc.; - dispensers for soaps, sanitizers, paper, etc.; - wound care: e.g. bandages, plasters as well as wound and infection management solutions for acute, chronic and complex wounds, etc.; - compression therapy: e.g., compression garments (such as stockings and arm sleeves), etc.; - orthopedics: mobilization and demobilization solutions for skeletal, muscular and joint injuries as well as other orthopedic treatment purposes (such as, inter alia, casts, splints, athletic tapes, leg / knee braces, etc.). The term “insulation material” as used herein refers to any fiber-based material that reduces or prevents the transmission of energy, such as heat. The term “packaging material” as used herein refers to any material to be used for the containment, protection, handling, delivery, storage, transportation, and presentation of goods, from raw materials to processed goods, from the producer to the user or consumer, including processor, assembler, or other intermediary. The packaging material may be a material that comes into direct contact with the product. The packaging material may be rigid or flexible. The term “filtration material” as used herein refers to any material which can separate a solid from a fluid (liquid or gas) by allowing the fluid to pass through, but not the solid. The term “thermoformable composite” as used herein refers to any thermoplastic material comprising a thermoformable polymer (biobased or from fossil origin; as described below) mixed with fibers, e.g., cellulosic fibers, which can be thermoformed into shaped structures. The term “layer” as used herein refers to the one or to one of several layers in the final fiber-based industrial material, e.g., after drying or after converting. The present disclosure encompasses a multilayer material comprising at least one layer that is made of a fiber-based industrial material with any one or several of the features described. The multilayer material may comprise two or more layers made of fiber-based industrial material or may comprise one or several layers (which may be mutually the same or mutually different) of other types. Multilayer structures may be used, e.g., as packaging materials, or other purposes. The term “fibrous foam” as used herein refers to a foam that comprises fibers. In this context, the term “foam” describes a cellular structure of gas bubbles separated by soft solid films or by a liquid media. The properties of the fibrous foam depend, in particular, on the air content and fiber consistency in the foaming slurry (which in turn determine the fiber volume fraction of the foam) as well as on the types of fibers used and the size and size distribution of the bubbles. The term "surface active agent” (or “surfactant”) as used herein refers to any agent which, even at low concentrations, effectively lowers the surface tension of a liquid, for example water, by selective adsorption on the interface. The surface active agent can be a pure chemical compound or a mixture of different chemical compounds. Examples of surface active agents include anionic, non-ionic, cationic, amphoteric, zwitterionic surface active agents, and combinations thereof. The term “fiber volume fraction” refers to the ratio between the volume of the fibers and the volume of liquid, gas, and solids (V / (V + V + V )) in the fibrous foam. Likewise, the term “solids volume fraction” refers to the ratio between the volume of the solids and the volume of liquid, gas, and solids (V / (V + V + V )) in the fibrous foam. In this context, the volume of a liquid (V ) can be determined using standard calibrated volumetric instruments, such as pipettes, burettes, graduated cylinders, and volumetric flasks. These instruments can be used to measure the volume of a liquid with high precision and accuracy. Such instruments can be calibrated according to ISO 4787:2021. The volume of fibers (V ) is defined as the ratio of fiber mass to fiber density. The fiber density – i.e., solids that are porous or have internal voids – can be determined by using, for example, the gas pycnometry method described in ISO 12154:2014. That is, the volume of solids is determined by measuring the change in pressure when a known volume of gas is displaced by the solids in a closed chamber. The fiber density can be calculated as the ratio of the mass to the gas-displaced volume. Typical fiber densities in the manufacturing method are from 0.90 to 1.80 g / cm (e.g., spruce kraft: 1.5 g / cm, eucalyptus kraft: 1.5 g / cm, single cellulose: 1.5 g / cm, flax: 1.43-1.52 g / cm, hemp: 1.47-1.50 g / cm, viscose: 1.52 g / cm, nylon 6,6: 1.14 g / cm, polyester: 1.38 g / cm, polypropylene: 0.90 g / cm). The volume of solids (V ) is defined as the sum of the volumes of every solid {i} present in the fibrous foam. The volume {i} can be defined as the ratio between the mass and the density of the solid {i}. The density of the solids can be determined as follows: -The density of solids that have regular shapes and canbe measured with a ruler or a caliper can be determined by using direct measurement of mass and volume. The mass can be measured with a balance and the volume can be calculated from the dimensions. The density is then the ratio of mass to volume; -The density of solids that have irregular shapes andcannot be measured directly can be determined by usingindirect volume measurement. The volume can be determined by displacing a known amount of liquid or gas with the solid and measuring the difference. The density is then the ratio of mass to displaced volume; -The density of solids that are insoluble and non-porouscan be determined by using hydrostatic weighing. The mass of the solid is measured in air and then in water (or another liquid). The difference in mass is equal to the buoyant force exerted by the liquid on the solid. The density is then calculated from the mass difference and the density of the liquid; -The density of solids that are porous or have internalvoids can be determined by using, e.g., the gas pycnometry methodology as described in the norm ISO12154:2014. The volume of the solid is determined by measuring the pressure change when a known amount of gas is displaced by the solid in a closed chamber. The density is then the ratio of mass to gas-displaced volume. The volume of gas (V ) can be determined by measuring the gas content of the fibrous foam. After measurement of V , V and V , the initial volume of the liquid prior to the foaming can be calculated as the sum of all those volumes. After the foaming, the volume of the fibrous foam (V ) can be determined with standard calibrated volumetric instruments such as pipettes, burettes, graduated cylinders, and volumetric flasks. These instruments can be used to measure the volume of a foam with high precision and accuracy. Such instruments can be calibrated according to ISO 4787:2021. - The gas content in the fibrous foam can be calculated as being: - The volume of gas (V )can be then calculated as being: The term “liquid slurry” as used herein refers to a liquid-solid suspension or a mixture of chemical components. The liquid slurry may, e.g., result from a liquid and a solid being contacted in a reactor or mixer. A liquid slurry may offer the benefit of better handling of the solid in the slurry and to obtain certain chemical reactions, or certain physical interactions. The term “fiber” as used herein refers to an elongated solid object having an apparent length greatly exceeding its apparent width, i.e., a length to diameter ratio of at least about 5, or at least about 10. Fibers are typically considered discontinuous in nature. Non-limiting examples of fibers include pulp fibers such as wood pulp fibers or annual plant fibers or synthetic staple fibers such as viscose and polylactic acid (PLA) fibers. The fibers may be mono-component or multi-component, such as bi- component fibers. Fibers as used herein may be fibers suitable for a process producing a fiber-based industrial material in general and in particular for a tissue making process or a nonwoven making process. The term “cellulosic fibers" (also known as “wood pulp fibers”, “annual plant pulp fibers” or “non-wood fibers”) characterizes fibers composed of or derived from cellulose. Applicable wood pulps include chemical pulps, such as Kraft, sulfite, soda, and sulfate pulps, as well as mechanical pulps including, for example, groundwood, thermomechanical pulp and chemically modified thermomechanical pulp. The term “manmade fiber” denotes a cellulosic or non-cellulosic, e.g., thermoplastic, fiber. Thus, the term “manmade fibers” covers “synthetic fibers”, as well as “semi-synthetic fibers” made from natural sources such as rayon. The term “hardwood fibers” as used herein refers to fibers derived from the woody substance of deciduous trees (angiosperms). Typically, hardwood fibers are short fibers having an average length of from 0.5 mm to 2 mm, a diameter of from 15 to 30 µm, and a wall thickness of from 2 to 3 µm. Hardwood fibers are usually pulped by the sulfite process or the kraft process. The term “softwood fibers” as used herein refers to fibers derived from the woody substance of coniferous trees (gymnosperms). Typically, the softwood fibers are “long” fibers having an average length of from 1.2 to 4 mm, a diameter of from 30 to 40 µm, and a wall thickness of from 3 to 4 µm. Softwood fibers are usually pulped by the kraft process. The term “non-wood fibers” as used herein refers to fibrous pulp derived from the non-woody substance of plants such as cotton, bagasse, hemp, miscanthus, sisal, straw, flax, or other plants. The term "natural cellulosic fibers” as used herein may be understood in particular to cover seed hair fibers, e.g., cotton, kapok, or milkweed; leaf fibers, e.g., sisal, abaca, pineapple, or New Zealand hemp; and bast fibers, e.g., flax, hemp, jute, or kenaf. The natural cellulosic fibers may originate from a plurality of natural sources" in addition to the fibers from waste such as bagasse and straw. The term “unrefined fibers” as used herein characterizes fibers as naturally occurring or being obtained by their respective preparation process (chemical or mechanical pulping, recycling etc.). Although being dependent on the fiber source, unrefined hardwood pulp fibers and softwood pulp fibers typically have a Schopper Riegler freeness value of about 12 to 15^SRV (wherein “SRV” stands for “Schopper Riegler (freeness) value”). Unrefined non-wood fibers pulp fibers (as coming from the pulp mill) can have a SR value in the range of 12 to 70°SRV. The term “refined fibers” as used herein characterizes to fibers which have been subjected to refining processes. Such processes are well known to those skilled in the art. Refined fibers typically have a freeness value of more than 15 SRV to 75 SRV. The term “primary pulp fibers” as used herein characterizes fibers as obtained from the pulping process of woody substances (e.g., hardwood, softwood) and non-woody substances (e.g., cotton, bagasse, hemp, miscanthus, etc.) which have not previously been used in a manufacturing process. The term “secondary pulp fibers” as used herein characterizes fibers that have previously been used in a manufacturing process (e.g., paper- or tissue-making), and have been reclaimed (recycled) as raw material for the manufacturing method of the present disclosure. Secondary pulp fibers can be recycled from, e.g., wastepaper, cardboard, or corrugated board, by common techniques in the art. The term “fiber length” as used herein characterizes the average length weighted by length (Lpl) of fibers determined using a MorFi LB01 device (lab equipment) by TECHPAP. According to the test procedure, a pulp sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each pulp sample is disintegrated in hot water and diluted to an approximately 0.001 % solution. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute solution when tested using a standard MorFi fiber analysis test procedure. The average length weighted by length (Lpl) of fibers may be expressed by the following equation: wherein, L is the length of a single fiber, and n is the total number of fibers measured. The term “rheology modifier” as used herein characterizes a substance that is capable of modifying the viscosity, in particular to increase the viscosity, of the medium with which it is mixed. Examples of rheology modifiers include, but are not limited to, cellulose ethers such as hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (CMC), hydrophilic polymers such as polyvinyl alcohols and polyethylene oxides, and polyamides. The term “slipping agent” as used herein characterizes asubstance that can reduce the friction and tackiness of thefibrous foam during the preparing step and subsequence method steps. Examples of slipping agents include, but are not limitedto, polyhydric alcohols such as glycerol, ethylene glycol andpropylene glycol, and polyether polyols. The term “filler” as used herein characterizes a material, in particular a particulate material, which can modify, e.g., improve, specific properties of the fiber-based industrial material, e.g., by affecting basis weight, mechanical and / or thermal stability, strength, elastic modulus, viscosity, color, etc. Examples of fillers include, but are not limited to, calcium carbonate, precipitated calcium carbonate (PCC), kaolin, bentonite, glass, polymers, magnesium hydroxide (talc), titanium dioxide, carbon black, bio-fillers (such as wood chips, saw dust, husk, etc.), and abrasive materials such as aluminum oxide and silicon carbide. The term “draining” as used herein refers to the reduction of liquid content, i.e., to drawing off liquid. In particular, it covers reducing a water content. Draining may also be referred to as deliquidization, and, when (mostly or only) water is drained, as dewatering. The term draining in particular encompasses mechanical techniques of reducing a liquid content, as opposed to drying which is to be considered a form of thermal reduction of liquid content. The term “defiberizing” as used herein refers to a process of separating a group or bundle of fibers into at least 65%, optionally 70%, or 75% of individual fibers. In particular, defiberizing involves mechanical techniques causing shear forces, such as hammermilling. The term “deflocculating” as used herein refers to a process of deflocculating fibers in a slurry or a foam (a fibrous foam) from a flocculent state to convert them into individual fibers. It in particular comprises dispersing and / or maintaining in a dispersed state. Deflocculating may in particular be promoted by adding deflocculants to a substance to be deflocculated such as electrolyte-sourcing liquids or powders such as sodium silicate, Darvan, Displex added in small amounts. The deflocculants may impart electrical charges to conglomerates of particles in a flocculated state in order to create a repelling force between such particles that drives them apart. The term “hammermilling” as used herein refers to a process of using a mill (also referred to as a hammermill) to shred and / or crush a substance or material into smaller pieces by repeated blow of little hammers. A hammermill may comprise a drum (e.g., a steel drum) containing a vertical or horizontal rotating shaft or drum on which hammers are mounted. The hammers are free to swing on the ends of a cross or fixed to the central rotor. The rotor is spun at a high speed inside the drum while material is fed into a feed hopper. The material is impacted by the hammer bars, defiberized, and expelled through screens in the drum of a selected size. The term “refining” as used herein refers to a mechanical treatment of a material comprising fibers that changes the properties, in particular, of the fibers. For example, refining may comprise fibrillation which involves the exposure of fibrils to increase the surface area of the fibers, thereby improving fiber–fiber bonding. Refining may be particularly useful for increasing of the strength of fiber-to-fiber bonds by increasing the surface area of the fibers and making the fibers more pliable to conform around each other. This may increase the bonding surface area and may lead to a denser end product. The term “headbox” or “die” as used herein refers to a device that distributes (or is configured to distribute) a continuous flow of slurry (e.g., a suspension of solids in a fluid, such as water) and / or foam and / or fibrous foam to a machine, optionally, at a constant rate and / or constant velocities, or that retards (or is configured to retard) the rate of flow, as to a top-feed filter, or for eliminating by overflow some of the finest particles. A headbox may in particular be a headbox tube bank apparatus that permits the flow of slurry therethrough. The headbox may in particular progressively improve the uniformity, stability, cleanliness of slurry and may lower turbulences of the slurry during flow thereof through the headbox. The term “cylinder mold former” as used herein refers to a forming device comprising a mesh-covered rotating cylinder partially immersed in a tank of fiber slurry, the rotating cylinder being disposed to rotate in a cylinder vat. The mesh covering the rotating cylinder may comprise two wires of different mesh. The inner-wire (also referred to as a backing wire) acts as a supporting base for the top wire (also referred to as a facing wire) and is usually around 10 to 15 mesh. The top wire is usually of around 35 of 80 mesh. The rotating cylinder is configured to drain water through the wire cloth leaving a fibrous deposit behind on its surface. A cylinder mold former may promote a random distribution of fibers and may promote high consistency. Cylinder mold diameters typically range up to around 2000 mm, and cylinder mould faces range up to around 5500 mm. A working speed may be in a range of around 100 to 400 m / min. The term “suction breast roll former” as used herein characterizes a type of former for tissue- and paper machines. The former includes a headbox to distribute the fiber suspension or the fibrous foam and to ensure a uniform fiber distribution in the planar fiber containing layer, a forming wire to receive the fiber suspension or the fibrous foam, to transport and to enable drainage, and a vacuum supported suction breast roll to initiate and control the web formation and web drainage. Also included within the term “suction breast roll former” are other embodiments of former for tissue- and paper machines, e.g., breast roll former comprising a solid breast roll and any kind of former for fourdrinier paper machines and former comprising cylindrical sleeves or forming cylinders, e.g., former for cylinder papermaking machines, or suction forming cylinder former and the like. The term “positive displacement pump” as used herein refers to a device that is configured to add energy to a fluid by applying force to a liquid with a mechanical device such as a piston or plunger. A positive displacement pump may decrease a volume containing the liquid until the resulting liquid pressure equals the pressure in the discharge system. This way, the potential energy is increased. The displacement pumps, referred to herein, may be rotary pumps, blow cases, or reciprocating pumps, as well as combinations thereof. In particular, the positive displacement pumps cover steam pumps, power pumps, controlled volume pumps, vane pumps, piston pumps, flexible member pumps, lobe pumps, gear pumps, circumferential piston pumps, and screw pumps. All percentages and ratios are calculated by weight unless otherwise indicated. 2. Method of manufacturing a fiber-based industrial material One aspect of the present disclosure relates to a method for manufacturing a fiber-based industrial material. 2.1 Fibrous foam preparation In one embodiment, the method comprises the step of preparing a fibrous foam. In one embodiment, the preparing may comprise dispersing solids and one or more surface active agents in a liquid, with a solids content of 5% to 60% by weight, at least 50% by weight of the solids are fibers, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content of 40% to 95% by weight, and supplying and dispersing gas in the liquid until a gas content of 64% or more by volume is reached. The liquid may be water or it may comprise water. The gas may be air or it may comprise air and other gases, such as nitrogen or carbon dioxide. The fiber content, surface active agents content and liquid content are based on the total weight of the fibrous foam. The gas content is based on the total volume of the fibrous foam. The liquid and / or the foam, in which the surface active agents, the fibers, and the gas are dispersed, which is supplied for the preparing may comprise at least 80% by weight of water. It may comprise at least 85%, at least 87%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% by weight of water. The gas, that is to be dispersed in the liquid and / or the foam, may comprise at least 95% air by volume. It may comprise at least 96%, at least 97%, at least 98%, at least 99%, at least 99.2%, at least 99.3%, at least 99.4%, or at least 99.5% by volume. The dispersing of gas in the liquid and / or the foam (while or after also dispersing fibers and surface active agents) leads to a gas-liquid dispersion. The gas liquid dispersion may have a liquid content of at least 80% by weight of water, and / or a gas content of at least 95% air by volume. The liquid content may be at least 85%, at least 87%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% by weight of water. A gas content of 64% or more, and, for example, an air content of 64% or more is where a jamming transition occurs between bubbly liquid and a wet foam (vol.% based on the total volume of the fibrous foam). The fibrous foam may, hence, be a wet foam. Alternatively, the fibrous foam may be a dry foam. A dry foam may have a gas content of 95% or more. A gas content of 64% or more provides the fibrous foam with appropriate properties, particularly in terms of rheology, thereby promoting homogeneous forming of the fibrous foam, as well as transporting. A gas content of 64% or more (above of the jamming transition) may help to prevent fiber flocculation (despite a high fiber consistency) and may provide a relevant yield stress and stability to the fibrous foam. The fibrous foam may first be prepared as a liquid slurry with a viscosity in the range of from 50 to 2000 Pa.s measured in accordance with the down-curve methodology at a shear rate of 0.01s (as described in section 2.f) below) and a storage modulus in the range of from 400 to 2500 Pa in the linear viscoelastic region (as described in section 2.f)). The fibrous foam may then be formed into a foam layer with a viscosity in the range of from 50 to 3000 Pa.s measured in accordance with the down-curve methodology at a shear rate of 0.01s (as described in section 2.f)) and a storage modulus in the range of from 500 to 10000 Pa in the linear viscoelastic region (as described in section 2.f)). The gas content of the fibrous foam may be 70% or more, 75% or more, or, in particular, 80% or more, 85% or more, 90% or more, or 92% or more (vol.% based on the total volume of the fibrous foam). A fibrous foam with 80% gas content or more may be particularly suitable for the manufacturing method. In one aspect, the prepared fibrous foam is stable. In this context, the term “foam stability” refers to the time span during which the foam maintains its initial properties as generated, such as gas content and / or rheological properties. Foam stability may be expressed in terms of “half-life”, which is the time required for half of the volume of liquid contained in the foam to revert to the bulk-liquid phase. The fibrous foam of the present disclosure may have a half-life of 2 min or more, or 3 min or more, or 4 min or more, or 5 min or more. The half-life of the fibrous foam may be determined by (1) taking a sample of the fibrous foam and measuring its gas content to determine the liquid volume of the fibrous foam, (2) pouring 1L of the fibrous foam in a graduated cylinder and start the chronometer, (3) stopping the chronometer when half of the liquid volume is drained at the bottom of the graduated cylinder and reporting this time as the half-life of the fibrous foam. The measurement is conducted in a conditioned laboratory (23°C, 50% relative humidity). The foam or fibrous foam can be prepared by any method enabling gas entrapment in the liquid including, e.g., chemical foaming, injection of pressurized gas and / or mechanical mixing. The foam or fibrous foam may be prepared by using, for example, a high consistency mixing apparatus. Non-limiting examples of suitable mixing apparatuses include the Pico-mix (available from Hansa Industrie-Mixer GmbH, Germany) and the Lamort mixer (available from Kadant Inc.). Depending on the type of mixer, rotor and desired foam properties, the mixer may be run at a speed of 100 rpm or more, or 200 rpm or more, and 5000 rpm or less, or 2000 rpm or less, or 1000 rpm or less, in particular 600 rpm or less. The prepared liquid phase may have a viscosity of from 1 to 500 centipoises (cP), or from 5 to 400 cP, or from 10 to 250 cP (23°C, 50% relative humidity), wherein 1 cP = 1mPa.s. The viscosity can be determined using a Brookfield viscosimeter (operating conditions: V60 or V12, spindle 61). The preparing may comprise supplying fibers. The fibers may be supplied as substantially individual fibers as obtained by a suitable chemical- and / or mechanical pretreatment, such as a pre-treatment with a debonder for fluff pulp, or CMC, and / or hammermilling. The supplied fibers may be dry or may be pretreated (e.g., pre-moisturized and / or fluff pulp pretreated with CMC, or another suitable agent) with a liquid (e.g., water) such that the liquid content of the fibers supplied is up to 80% by weight, or up to 60% by weight, such as about 40% by weight, based on the total weight of the (pretreated) fibers. The preparing of the fibrous foam may comprise pre-moisturizing the fibers and mixing, optionally with a paddle mixer, until a solids content in the range of 30% to 50% by weight is reached, to form pre-moistened fibers, the solids content being based on the total weight of the pre-moistened fibers. A fiber content may be 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more, and 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, or 35% by weight or less, or 30% by weight or less, based on the total weight of the fibrous foam. A fiber content of 5% by weight or more, particularly 10% by weight or more, or greater than 10% by weight promotes foam stability, homogenous formation and / or desirable product properties, such as basis weight and density. In addition, a fiber content of 5% by weight or more results in a fibrous web that requires less draining (e.g., dewatering) and / or drying, thereby promoting energy efficiency of the manufacturing method. A fiber content greater than 60% by weight may not be desirable as it may promote flocculation or cause jamming problems in the machine. The supplied fibers may be natural and / or manmade fibers. In particular, the fibers may comprise pulp fibers including, but not limited to, chemical pulp fibers, mechanical fibers that have undergone chemical pre-treatment, and mixtures thereof. In this context, the term "chemical pulp" refers to a fibrous material obtained from plant raw materials from which most of the non-cellulosic components have been removed by chemical pulping without substantial mechanical post-treatment (in accordance with DIN 6730). When a mixture of natural and manmade fibers is supplied, it may be desirable that at least 25% by weight, 50% by weight, or at least 80% by weight, or at least 90% by weight, or at least 95% by weight of the fibers are natural fibers, based on the total weight of the fibers supplied. In one aspect, the supplied fibers may be only natural fibers or only manmade fibers. The supplied fibers may only be cellulose based fibers, in order to produce a recyclable material. This may promote sustainability. The “natural fibers” may be any wood fibers and / or non-wood fibers commonly used in papermaking. The natural fibers may originate from a plurality of natural sources. The fibers may be pulp fibers obtained by any suitable pulping process. In particular, the pulp fibers may be obtained by, e.g., the kraft pulping process, the soda pulping process, the sulfite pulping process, the chemical pulping process, the chemi-mechanical pulping (CMP) process, the thermomechanical pulping (TMP) process, the chemi-thermomechanical pulping (CTMP) process, the bleached chemi-thermomechanical pulping (BCTMP) process, or the pressure / pressure thermomechanical pulping process (PTMP). The pulp fibers may be bleached by using chlorine-free bleaching steps in view of the production of environmentally sound products and process steps. In one aspect, the pulp fibers are obtained by the soda pulping process or the CTMP process as described,e.g., by Cappelletto et al. in Industrial Crops and Products, 11(2000) 205-210. The wood pulp fibers may be ground wood pulp fibers. In one aspect, the wood pulp fibers may be selected from pulp fibers comprising hardwood fibers, such as eucalyptus, beech, aspen, acacia or birch fibers, and softwood fibers, such as pine, spruce, red cedar, Douglas fir, hemlock, or larch fibers. Softwood fibers particularly useful in the present method are Northern Bleached Softwood Kraft (NBSK) fibers. The wood pulp fibers may be a mixture of pulp fibers comprising hardwood and softwood fibers. In one aspect, the weight ratio of hardwood fibers to softwood fibers may be from 80 / 20 to 0 / 100, or 50 / 50 to 0 / 100, or 30 / 70 to 0 / 100. Softwood fibers may promote desirable strength and / or rheological properties, while hardwood fibers may contribute to achieving good softness. The wood pulp fibers may be refined or may be unrefined. In one aspect, at least a part of the softwood fibers to be used are refined and / or at least a part of the hardwood fibers to be used are unrefined. The softwood fibers may be refined to a degree of freeness of 19 to 35°SRV, in particular, 19 to 26°SRV, such as 19 to 24°SRV. In one aspect, the hardwood pulp fibers originate from eucalyptus and / or the softwood pulp fibers are Northern Bleached Softwood Kraft (NBSK) fibers, wherein the NBSK fibers are optionally refined to a degree of freeness of 19 to 35°SRV, in particular 19 to 26°SRV, such as 19 to 24°SRV. The non-wood fibers may be selected from cotton, bagasse, hemp, miscanthus, sisal, straw and flax fibers. The non-wood fibers may be refined or may be unrefined. The non-wood fibers may be bleached or unbleached. The pulp fibers used in the present manufacturing method may be a primary fibrous material (e.g., soft-wood, hard-wood, or non- wood fibers such as straw or bagasse), a secondary fibrous material (i.e., a fibrous material comprising secondary pulp fibers), and mixtures thereof. In one aspect, (i) all fibers present in the tissue paper web are primary pulp fibers, or (ii) a mixture of primary and secondary (recycled) pulp fibers. The manmade fibers may be cellulosic fibers and / or non- cellulosic fibers. The manmade fibers may be any fibers used in the manufacture of substrates and formed by an appropriate technique such as spinning. Cellulosic manmade fibers may be selected from: - regenerated cellulose, such as rayon, viscose, lyocell, acetate and other fibers derived from cellulose, and - modified fibers such as modified southern pine fibers (sold, for example, under the trade name Helix fibers). Regenerated cellulose may be obtained by conversion of natural cellulose to a soluble cellulosic derivative and subsequent regeneration of the cellulose, typically forming fibers or filaments. The use of the cellulosic manmade fibers contributes to the provision of a bio-based, sustainable product. Examples of regenerated cellulose suitable for the manufacturing process include but are not limited to Lyocell, Tencel, Newcell, Seacell, and Excel fibers. In one aspect, the cellulosic manmade fibers have not been chemically modified. Examples of cellulosic manmade fibers that have not been chemically modified include viscose and lyocell. Use of cellulosic filaments formed of natural cellulose that has not been chemically modified further contributes to the provision of a plastic free product. The manmade cellulosic fibers may comprise a plurality of fiber types. Non-cellulosic manmade fibers may be selected from polyesters (e.g., polyalkylene terephthalate (PET), polybutylene terephthalate (PBT), (biobased) polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate-co-adibate (PBSA), polyhydroxyalkanoates (PHA), and the like), polyolefins (e.g., polyethylene, polypropylene and the like), polyamides (e.g., nylons such as nylon-6, nylon-6,6, nylon 6,12 and the like), and polyacrylonitrile (PAN). In one aspect, the supplied fibers may comprise multi- or bi- component fibers such as fibers having a core / sheath structure, e.g., fibers wherein the core is made of a first material and the sheath is made of another material. An example of a useful bicomponent fiber, i.e., xylan-enriched viscose, has beendescribed by Hutterer et al. (see BioResources 2017, 12(3), 5632-5648). Further useful fibers include, but are not limited to, polyethylene-polypropylene fibers. Bicomponent fibers may be useful in order to improve the bonding between fibers. The natural fibers may have an average fiber length of from 0.2 mm to 40 mm, or from 0.3 mm to 30 mm, or from 0.3 mm to 25 mm, or from 0.5 to 20 mm, or from 0.5 to 3 mm. The manmade fibers may have any desirable average fiber length. However, the manmade fibers may be prepared to have an average fiber length of from 0.2 mm to 50 mm, or from 0.5 mm to 30 mm, or from 1 mm to 25 mm. In one aspect, the manmade fibers may be staple fibers, which are cut to a specific length for the manufacturing method of the present disclosure. The staple fibers may be formed of polyethylene, polypropylene, polyester (e.g., polylactide, polyhydroxyalkanoate), polyamide, or cellulose, preferably of polylactide, polyhydroxyalkanoate or cellulose, more preferably of cellulose. The use of staple fibers formed of polylactide, polyhydroxyalkanoate or cellulose contributes to the provision of a biodegradable and compostable product. The staple fibers may be formed of bio-based polyethylene, bio-based polypropylene, bio-based polyester, or bio-based polyamide. The use of staple fibers formed of bio-based polyethylene, bio-based polypropylene, bio-based polyester, or bio-based polyamide contributes to the provision of a bio-based product. Furthermore, the staple fibers may be formed of cellulose of natural origin, such as regenerated cellulose (as described above). The use of staple fibers formed of cellulose of natural origin contributes to the provision of a bio-based, sustainable product. The manmade staple fibers as used herein may have an average length of from 5 to 25 mm, or 5 to 20 mm. When the method is for manufacturing a thermoformable composite, natural fibers mixed with at least one thermoplastic polymer may be supplied. The at least one polymer may be selected from carbohydrate derivatives, (bio)polyesters (such as polylacticacid, polybutylene succinate, polyhydroxyalkanoates),polyurethane, and polyolefins. Examples of suitable carbohydrate derivatives include cellulose derivatives, e.g., cellulose esters, starch and dextrin derivatives, and mixture of two or more derivatives. While the supplying of fibers has been mentioned, the preparing step may, more generally, comprise supplying solids. In other words, the solids comprise the fibers and may comprise further solids. In this context, the further solids may be selected, for example, from fillers, pigments and other solid materials commonly used in industrial materials. Examples of fillers are clay (or kaolin), calcined clay (or kaolin), ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), titanium dioxide, satin white, zinc oxide, barium sulfate, gypsum, silica, alumina trihydrate, talc, mica and diatomaceous earth, and bio-fillers such as wood chips, saw dust, husk, etc. A solids content may be 5% to 60% by weight based on the total weight of the fibrous foam, and at least 50% by weight of the solids may be fibers. At least 55%, 60%, 65%, 70%, 75%, 80%, or 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers. All of the solids may be fibers. The prepared fibrous foam may have a solids content of more than 5%, or more than 10% by weight, or more than 15% by weight. In particular, the prepared fibrous foam may have a fiber content of more than 10% by weight. This may offer a particularly beneficial consistency for a fiber-based industrial material. The solids content may, in particular, be more than 12% by weight. In particular, the fiber content may, be more than 12% by weight. The increased solids content (or fiber content) may offer a particularly beneficial consistency for a fiber-based industrial material. The solids content (or, in particular, the fiber content) may, in particular, be more than 14%, 16%, 17% 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25% by weight. The increased solids content (or fiber content) may offer a particularly beneficial consistency for a fiber-based industrial material. The preparing may comprise supplying one or more surface active agents. The surface active agents are not particularly limited as long as they can be used to generate foam. The surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, zwitterionic surface active agent(s), amphoteric surface active agents, and nonionic surface active agents. The surface active agent(s) may be polymeric or protein-based. The anionic surface active agent(s) may be selected from anionic sulfates, alkyl ether sulfonates, alkyl aryl sulfonates (e.g., (di)alkyl(di)benzene sulfonic acid, alkylphenol sulfonic acid, and the like), alkali metal sulforicinates, sulfonated glyceryl esters of fatty acids, salts of sulfonated monovalent alcohol esters, metal soaps of fatty acids, amides of amino sulfonic acids (e.g., 2-acrylamido-2-methylpropane sulfonic acid), sulfonated amides of amino sulfonic acids, sulfonated products of fatty acid nitriles, alkali metal alkyl sulfates (e.g., sodium dodecyl sulfate (SDS), sodium laurate, sodium laureth sulfate), ether sulfates, sulfuric acid esters of polyoxyethylene alkyl ethers, salts of alkyl naphthyl sulfonic acid, phosphate esters in particular sodium lauryl phosphate esters, and combinations thereof. The cationic surface active agent(s) may be selected from fatty acid amines and amides and salts thereof (e.g., dodecyl amine acetate, tallow fatty acids acetate, dodecyl aniline, undecylimidazoline, and the like), mono-, di-, or tri-carbyl ammonium or phosphonium salts, carbylcarboxy salts, quaternary ammonium salts (e.g., dioctadecyldimethyl ammonium chloride, didodecyldimethyl ammonium chloride, dihexadecyl ammonium chloride, and the like), imidazolines, ethoxylated amines, quaternary phospholipids, and combinations thereof. The zwitterionic surface active agent(s) may be selected from betaines and mixtures thereof. Examples of zwitterionic surface active agent(s) include, but are not limited to, cocodimethyl carboxymethyl betaine, cocoamidopropyl betaine, lauryl amidopropyl betaine, lauryl betaine, betaine citrate, sodiumhydroxymethyl glycinate, carboxymethyl)dimethyl-3-[(1 -oxododecyl) amino] propylammonium hydroxide, coco alkyldimethyl betaines, (carboxymethyl) dimethyloleylammonium hydroxide, cocoamidopropyl betaine, (carboxylatomethyl) dimethyl(octadecyl)ammonium, and combinations thereof. The amphoteric surface active agent(s) may be selected from sodium acyl amphoacetates, sodium acyl amphopropionates, disodium acyl amphodiacetates and disodium acyl amphodipropionates where the alkanoyl group may comprise a C7- C18 alkyl portion. Examples of amphoteric surfactants include, but are not limited to, sodium lauroamphoacetate, sodium cocoamphoacetate, sodium lauroamphoacetate, sodium cocoamphoacetate, and combinations thereof. The nonionic surface active agent(s) may be selected from amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, sucrose esters, and combinations thereof. In particular, the nonionic surface activeagent(s) may be selected from alkylglucosides,alkylpolyglucosides, alkoxylated fatty alcohols, and combinations thereof. In one aspect, the nonionic surface active agent(s) may have the following general formula (1): R1-O-(R2)n-H (1)wherein, R1is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R2is a hexose or pentose unit, and n is 1 to 5. In the general formula (1), R1may be a linear or branched hydrocarbon group having from 6 to 18 carbon atoms, or from 8 to 16 carbon atoms, in particular 10 carbon atoms. R1may a linear hydrocarbon group of formula –(CH2)n’-CH3wherein n’ is 3 to 19, or 5 to 17, or 7 to 15, in particular 9. R2may be a hexose unit or may be a pentose unit. n may be 1 to 4, in particular 1 or 2. In one aspect, the nonionic surface active agent(s) may have the following general formula (2):CH3–(CH2)n’-O-(R2)n-H (2)wherein, R2is a hexose unit, and n is 1 or 2. A particularly suitable alkylpolyglucoside is Simulsol SL10 (available from Seppic, France). A surface active agents content may be from 0.02% to 1.20% by weight based on the total weight of the fibrous foam. In one aspect, the surface active agents content may be from 0.05% to 1.0% by weight, or from 0.1% to 0.8% by weight, or from 0.2% to 0.7% by weight. A content of less than 0.02% by weight may not produce a foam with adequate gas (e.g., air) content and / or stability, while a content of more than 1.20% by weight may not be cost effective. In one aspect, the preparing of the fibrous foam may comprise supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent. The preparing may comprise supplying only one or more nonionic surface active agents. In this context, the at least one nonionic surface active agent(s) may be selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, and sucrose esters. The at least one nonionic surface active agent may be selected from alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols. In one aspect, the at least one nonionic surface active agent may have the above general formula (1), or the above general formula (2). When a mixture of surface active agents is used, the at least one nonionic surface active agent may be comprised in an amount of at least 50% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight based on the total weight of the mixture. The liquid may comprise at least 80% by weight of water. Alternatively, the liquid may comprise at least 85%, 90%, 96%, 97%, 98%, 99%, 99.5%, or at least 99.8% by weight of water. The use of significant amounts of water as the liquid may promote cost efficiency. The liquid may also comprise a polar solvent except water, in particular an alcohol, such as ethyl alcohol or isopropyl alcohol. Such a polar solvent may be comprised in an amount of 10% by weight or less, in particular 5% by weight or less based on the total weight of the liquid supplied. The liquid may comprise further components including one or more binders, one or more rheological modifiers, and other additives, which are soluble therein. The gas may comprise at least 95% air by volume. Alternatively, the gas may comprise at least 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% of air by volume. The use of significant amounts of air as the gas may promote cost efficiency. In one aspect, the gas may comprise nitrogen and / or carbon dioxide. The gas may also be a mixture of air with nitrogen and / or carbon dioxide, wherein the mixture optionally comprises at least 10% air by volume, or at least 50% air by volume, or at least 90% air by volume. The use of nitrogen and / or carbon dioxide as the gas may promote foam stability. The preparing may comprise supplying one or more binders. The use of one or more binders may be advantageous for stabilizing the porous structure and / or improving the strength properties of the material. The binder(s) that may be used in the manufacturing method are not particularly limited and may be selected from, for example, strength resins commonly used in papermaking. In one aspect, the binder(s) may be selected from wet strength agents and dry strength agents. The wet strength agent(s) may be selected from urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, polyethylene imines, polyvinylamines, polyureide-formaldehyde resins, glyoxal-acrylamide resins and cationic materials obtained by the reaction of polyalkylene polyamines with polysaccharides such as starch and various natural gums, as well as 3-hydroxyazetidinium ion-containing resins, which are obtained by reacting nitrogen- containing polymers with epichlorohydrine. Suitable materials are described in further detail in US 3,998,690 and EP 1583 869 B1. In particular, the wet strength agent(s) may be selected from polyaminoamide-epichlorohydrine resins,polyamide-epichlorihydrin (PAE) resins, polyamine-epichlorohydrine resins and aminopolymer-epichlorohydrine resins. Examples of these resins are the commonly used Kymene resins (available from Ashland). The dry strength agent(s) may be selected from polycarboxylic acids and anhydrides such as starch-based polymers, (meth)acrylic acid-derived polymers and copolymers, modified polyacrylamides, saccharides, polyvinyl alcohols, copolymers derived from maleic anhydride, vinyl copolymers of carboxylic acids and cellulose-based polymers. Cellulose ethers, in particular carboxyalkylated polysaccharides and carboxyalkylated cellulose derivatives, are especially suitable for use in the present method. The cellulose ethers include carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), methyl ethyl cellulose (MEC), hydroxyethylmethyl cellulose (HEMC), hydroxypropylmethyl cellulose (HPMC) guar, locust bean gum, carboxymethyl starch and the like, and their alkali metal salts or ammonium salts. Sodium carboxymethyl cellulose (CMC) is particularly suitable for the present method. In one aspect, the binder(s), e.g., polysaccharides such as CMC and modified starches, may also be capable of modifying the rheological properties, in particular to increase the viscosity, of the fibrous foam. In this case, it is understood that the binder(s) may be used alone or in combination with one or more other rheology modifiers (described further below). In one aspect, the fibrous foam comprises one or more binders (e.g., CMC) and is substantially free of other rheology modifiers. In this context, the term “substantially free” means that other rheology modifiers are not supplied or supplied such that their content is less than 0.05% by weight, or less than 0.02% by weight, based on the total weight of the fibrous foam. The content of the binder(s) as described above, if present, may be from 0.005 to 30% by weight, or from 0.01 to 28% by weight, or from 0.05 to 25% by weight, or from 0.10 to 20% by weight, or from 0.10 to 15% by weight based on the total weight of the fibers supplied. In addition, the binder(s) may be selected from latexes such as anionic styrene-butadiene copolymers, anionic styrene­butadiene copolymers, polyvinyl acetate homopolymers, vinyl-acetate ethylene copolymers, vinyl­acetate acrylic copolymers, ethylene- vinyl chloride copolymers, ethylene-vinyl chloride-vinyl acetate terpolymers, acrylic polyvinyl chloride polymers, acrylic polymers, nitrile polymers, and combinations thereof. The content of the latex(es), if present, may be from 5.0 to 20.0% by weight, or from 10.0 to 15.0% by weight, based on the total weight of the fibers supplied. In one aspect, the binder(s) may be selected from microfibrillated cellulose (MFC) fibers, nanofibrillated cellulose (NFC) fibers, and mixtures thereof. The use of MFC and / or NFC fibers as a binder may promote desirable strength and haptic properties. The content of the MFC / NFC fibers, if present, may be from 0.5 to 20.0% by weight, or from 0.8 to 10.0% by weight, or from 1.0 to 5.0% by weight, based on the total weight of the fibers supplied. The preparing may comprise supplying one or more rheology modifiers. The rheology modifier(s) may be particularly useful in order to defiberize the fibrous material and / or achieve desirable rheological properties for forming. The rheology modifier(s) may be selected from water-soluble substances commonly used in papermaking including, but not limited to, cellulose ethers such as hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose, hydrophilic polymers such as polyvinyl alcohols and polyethylene oxides, polyamides, and combinations thereof. In this context, the term “water soluble” means that a solubility in water at 25°C of at least 40g / l, or at least 200g / l, in particular 500g / l. Cellulose ethers such as sodium carboxymethyl cellulose (e.g., available under the tradename Carbocell) are particularly suitable for the present method. In one aspect, the supplied one or more rheology modifiers have a viscosity of from 10 to 2500000 cP, or from 100 to 140000 cP, or from 200 to 12000 cP, or from 300 to 6500 cP, or from 700 to 3000 cp, or from 750 to 2500 cP, or from 800 to 2000 cP, or from 800 to 1500 cP (as measured using a Brookfield viscosimeter and a 1% solution in water at 25°C). The content of the rheology modifier(s), if present, may be from 0.001 to 10 % by weight, or from 0.001 to 5 % by weight, or from 0.001 to 2 % by weight, or from 0.001 to 1 % by weight, or from 0.001 to 0.5 % by weight, or from 0.001 to 0.25 % by weight, or from 0.001 to 0.15 % by weight, or from 0.001 to 0.1 % by weight, or from 0.001 to 0.05 % by weight based on the total weight of the fibers supplied. The preparing may comprise supplying one or more slipping agents. The slipping agent(s) may be advantageous to reduce the friction and tackiness of the fibrous foam in the preparing and subsequent method steps. The slipping agent(s) may be selected from polyhydric alcohols such as glycerol, ethylene glycol and propylene glycol, polyether polyols, and combinations thereof. In one aspect, the slipping agent (s) may be a polyether polyol selected from polyethylene glycol, polypropylene glycol, and combinations thereof. In particular, the slipping agent (s) may be polyethylene glycol having, optionally, a number-average molecular weight of from 100 to 1000000, or from 500 to 500000, or from 800 to 250000, or from 1000 to 20000, or from 1500 to 10000 as determined by a suitable technique, such as Gel Permeation Chromatography (GPC). The content of the slipping agent(s), if present, may be from 0.001 to 10 % by weight, or from 0.001 to 5 % by weight, or from 0.001 to 2 % by weight, or from 0.001 to 1 % by weight, or from 0.001 to 0.75 % by weight, or from 0.001 to 0.5 % by weight, or from 0.001 to 0.3 % by weight, or from 0.001 to 0.2 % by weight, or from 0.001 to 0.15% by weight, or from 0.001 to 0.10% by weight based on the total weight of the fibers supplied. The preparing may comprise supplying one or more fillers. The filler(s) may be advantageous modify, e.g., improve, the properties fiber-based industrial material, e.g., by changing basis weight, mechanical and / or thermal stability, strength, elastic modulus, viscosity, color, etc. In one aspect, the filler(s) may be a particulate material. The filler(s) may be selected from calcium carbonate, precipitated calcium carbonate (PCC), kaolin, bentonite, glass, polymers, magnesium hydroxide (talc), titanium dioxide, carbon black and bio-fillers such as wood chips, saw dust, husk, etc. It will be appreciated that mixtures of two or more of the aforementioned fillers may also be used. The particle diameter of the filler(s) may be below 2 μm, e.g., between 40% and 90% of the filler particles aresituated below a diameter of 2 μm.The content of the filler(s), if present, may be from 0.005 to 30% by weight, or from 0.01 to 28% by weight, or from 0.05 to 25% by weight, or from 0.10 to 20% by weight, or from 0.10 to 15% by weight based on the total weight of the fibers supplied. The preparing may comprise supplying one or more additives. The additives may be selected from softeners, debonders, retention agents, expanding microcapsules (e.g., Expancel microspheres) pH modifiers, colorants, dyes and the like. In this context, it is understood that the additive(s) are soluble and / or dispersible in the liquid and distinguished from the solids described above. The content of the additive(s), if present, may be from 0.001 to 0.5 % by weight, from 0.001 to 0.3 % by weight, from 0.001 to 0.2 % by weight, or from 0.005 to 0.18% by weight, or from 0.01 to 0.15% by weight, or from 0.01 to 0.10% by weight based on the total weight of the fibers supplied. In one embodiment, the method includes the step of preparing a fibrous foam comprising fibers, a liquid, and a gas, wherein a fiber volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less. The liquid may be water, or it may comprise water. The gas may be air, or it may comprise air. While fibers have been mentioned, the prepared fibrous foam may, more generally, comprise solids, and a solids volume fraction may be 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less. At least 50% by weight of the solids may be fibers. At least 55%, 60%, 65%, 70%, 75%, 80%, or 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers. All of the solids may be fibers. A fiber content may be from 5% to 60% by weight. A liquid content may be from 40% to 95% or 45 to 95%, 50% to 95%, or 55% to 95% by weight. A gas content may be 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume. The preparing may comprise supplying a rheology modifier. The rheology modifier may be used to decrease or increase the viscosity of the fibrous foam and may promote stability. The method may comprise, prior to the step of preparing the fibrous foam, a step of preparing a liquid slurry comprising at least one component selected from the group consisting of: liquid, e.g., water, fibers, a surface active agent, a binder, and a slipping agent. The preparing of the fibrous foam may comprise supplying at least one surface active agent or a mixture of surface active agents. In particular, any one or several of the surface active agents or types of surface active agents defined in this disclosure may be supplied. In particular, the surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents. The preparing of the fibrous foam may comprise supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent, the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols,alkoxylated alkylphenols, fatty acid monoglycerides,polyoxyethylene sorbitan, and sucrose esters. The at least one nonionic surface active agent may be selectedfrom the group consisting of alkylglucosides,alkylpolyglucosides, and alkoxylated fatty alcohols, the at least one nonionic surface active agent being optionally an alkylpolyglucoside of the general formula (1): R1-O-(R2)n-H (1)wherein, R1is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R2is a hexose or pentose unit, and n is 1 to 5. The preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means may be promoted by the same mechanical movement. This may particularly promote process efficiency and / or allow lowering the specific energy consumption. 2.2 Formation of the fibrous foam into a foam layer The method may comprise a step of forming the fibrous foam into a foam layer. The forming into a foam layer may in particular involve bringing the fibrous foam into a planar form. A foam layer has two dimensions of extension (two directions of a planar surface) and a dimension of thickness, wherein the foam layer is thin in the dimension of thickness as compared to the dimensions of planar extension. The form of a foam layer may be beneficial in terms of allowing draining, in particular, mechanical draining, but also allowing thermal drying. Moreover, the foam layer may be considered a step towards the desired form of a fiber-based material that is the base material of industrial materials such as insulation, packaging, filtration, construction, thermoformable composite and / or growth media materials. The forming of the fibrous foam into a foam layer may comprise bringing the fibrous foam into a planar layer. The planar form may allow for an efficient draining (in particular, for a dewatering). The method may comprise bringing one or several of a liquid slurry, a foam, solids, liquid, and the fibrous foam into contact with at least one rotatable means, such as a screw, and rotating the at least one rotatable means to transport the fibrous foam. The rotating of the at least one rotatable means (e.g., a screw) may effect the mechanical draining / dewatering or it may contribute to the draining / dewatering. The rotating of the at least one rotatable means may also transport and / or process the fibrous foam or contribute to processing the fibrous foam. The at least one rotatable means (e.g., a screw) may be rotated with from 100 to 5000 revolutions per minute, or with 500 to 3000 revolutions per minute, or 800 to 2800 revolutions per minute, or 1000 to 2500 revolutions per minute, or 1600 to 2400 revolutions per minute. The rotatable means may be comprised by a high shear mixer, and the speed at which the mixer is run may be 100 rpm or more. The speed may be 200 rpm or more and 5000 rpm or less, or 200 rpm or more and 2000 rpm or less, or 200 rpm or more and 1000 rpm or less, or 200 rpm or more and 600 rpm or less. The forming of the fibrous foam into the foam layer may be at least in part performed in one or several of the following devices: a die, a headbox, and a cylinder mold former. The die may be a slot die with an adjustable die gap. The fibrous foam may be processed into a continuous fibrous web or sheet on a moving continuous dewatering / conveyor unit. The forming the fibrous foam into the foam layer may comprise bringing the fibrous foam into a planar form. A planar form is a form in which one dimension of the foam (orthogonal to the plane of the planar form) is much thinner than the dimension in the planar directions. The forming means that performs the forming (or which may be configured to perform the forming) may comprise at least one foam shaping part (a flow part) over which a fibrous foam flows, in order to be brought into a planar form. In particular, a die and / or a headbox and / or a cylindrical mold may have an outlet opening with a cross-section perpendicular to a flow direction of the fibrous foam and having a long axis, which may also be referred to herein as a width of the outlet opening, and a short axis, which may also defined herein as a height of the outlet opening, wherein a ratio between a long axis dimension and a ratio between a short axis dimension is in a range of 2 or more, 4 or more, 6 or more, 8 or more, or 9 or more, or 10 or more, or 11, or 12, or 13 or more. The forming means may comprise two or more foam shaping parts. The short axis of the outlet opening of the forming means may have a dimension of at least 0.5 mm, or at least 0.8 mm, 0.9 mm, or 1.0 mm. These minimum short axis dimensions, to an increasing degree with increasing minimum value, may be suitable to prevent or even avoid clogging. The outlet short axis (referred to as a height in particular in the case in which the short axis is oriented in the direction of gravity or substantively in the direction of gravity) may be a slit opening. The outlet short axis dimension may be in a range of from 0.5 mm to 100 mm, 1.0 mm to 80 mm, 2 mm to 70 mm, or 5 mm to 50 mm, such as about 10 mm. The forming means may comprise an inlet defined by a width of a cross-section perpendicular to a flow direction of the fibrous foam and having a long axis, which may also be referred to herein as a width of the outlet opening, and a short axis, which may also defined herein as a height of the opening. The long axis of the inlet opening may be at least 1.5, 2.0, 3.0, 5.0, or 8.0 times larger than the short axis of the outlet opening. The outlet height, or, more generally, the opening size (e.g., a size of an outlet surface cross-section) may be adapted to a desired foam consistency and / or product application. The foam consistency, the fiber volume fraction, and / or the air content may be adapted to achieve a desired target basis weight and / or density of the material. In addition, also the solids volume fraction in general, and, in particular, the fiber volume fraction may be tailored to the desired basis weight and / or density. The forming means may comprise a lateral spread-out part that is shaped as to promote a lateral spreading out of foam, in order to increase the ratio of the MD / CD dimension of the foam. The forming means may comprise or consist of a die and / or a headbox and / or a cylindrical mold and / or a suction breast roll former. The forming means may comprise or consist of a plurality of dies or headboxes or cylinder mold formers or suction breast roll formers (or combinations thereof). The plurality of dies or headboxes or cylinder mold formers or suction breast roll formers (or combinations thereof) may be used to make multilayered materials or structures. The forming of the fibrous foam into the foam layer may be fully performed in the forming means, and in particular, e.g., in one or several die(s) and / or one or several headbox(es). 2.3 Draining (in particular: dewatering) and drying The method may comprise processing the foam layer into a fibrous web or sheet, e.g., by draining and / or drying. In particular, the method may comprise a step of draining the fibrous foam in the foam layer to form a fibrous web or sheet, wherein the fibrous web has a liquid content of 20% to 85% by weight (or a solids content of 15% to 80% by weight). The liquid content of 20% to 85% of the fibrous web or sheet may be considered a remarkably low liquid content as a starting point for a subsequent drying step. This may allow lowering the specific energy consumption and promoting being able to reach a desired dryness level of a product. For example, the liquid content at the end of the draining step may be half of the liquid content encountered in comparable manufacturing methods prior to a drying step. This may allow saving up to 80%, in particular at least 50% of the energy that will be needed to appropriately dry the product during a subsequent drying step. The liquid content of the fibrous web or sheet may be 25% to 85% by weight, or 30% to 80% by weight, or 40% to 80% by weight, or 50% to 80% by weight, or 50% to 75% by weight. The draining of the fibrous foam may comprise mechanical draining. Mechanical draining relies on the use of mechanical force to remove liquid. When the liquid is water (or substantially water), the mechanical draining can also be referred to as mechanical dewatering. The mechanical draining may be intensified by increasing a temperature of the liquid prior to the mechanical draining. The mechanical draining may allow for a reduction of liquid content and, hence, for lowering a specific energy consumption during thermal draining (in particular, thermal dewatering), i.e., for reducing the specific energy consumption. This may promote energy savings and, hence, promote environment friendliness. The dewatering of the fibrous foam may comprise mechanical dewatering. Mechanical dewatering relies on the use of mechanical force to remove water. The draining of the fibrous foam may comprise or consist of suction and / or mechanical draining, such as pressing. The dewatering may comprise or consist of mechanical dewatering, such as pressing. The dewatering is in this context be understood not to comprise drying, i.e., the dewatering is in this context to be considered separate from thermal draining (in particular, thermal dewatering) in the sense of drying. The draining may comprise applying a vacuum to the foam layer with a constant pressure or with a varying pressure. The variation may be a temporal or a spatial variation. In other words, the pressure may be increased or lowered as a function of time. In addition or alternatively thereto, the pressure may be higher or lower up- and downstream (i.e., a spatial pressure variation). The varying pressure may be a pressure that has at least one decrease in a downstream direction of transportation. The pressure may, e.g., be successively increased and decreased, re- increased, etc. The draining may be performed by successively applying at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure. In-between these stages, the pressure may or may not be lowered. In other words, there may be several stages of increasing and decreasing the pressure. The pressing may be performed by a pressing means comprising a hydraulic press, or one or more press rolls. The pressing may lead to a significant reduction of the liquid content in the fibrous layer and / or increase of density. In one aspect, the increase in density may be of 50 to 500% with respect to the density of the unpressed material. The force applied in the pressing may be of 200 kPa to 20 MPa, or 500 kPa to 15 Mpa, or 1 Mpa to 10 MPa. The method may comprise a drying step of drying the fibrous web to obtain a fiber-based industrial material. The specific energy consumption for the drying may be lowered as compared to when relying on conventional manufacturing processes. One of the reasons may lie in the significantly lower liquid content of the fibrous web as compared to known intermediate products. Moreover, the drying may bring down the liquid content to the level needed for an industrial material. The drying may comprise thermal drying. The drying may comprise freeze drying. The drying may comprise infrared drying. The drying may comprise contact drying. The drying may comprise impingement drying. The drying may comprise microwave drying. The drying may comprise through air drying. The drying may comprise any combination of the mentioned types of drying and repeated steps of drying. The drying may, in particular, be considered thermal drying, as opposed to mechanical draining. The step of drying may be performed, and the fiber-based industrial material obtained may have a liquid content of 1% to 15% by weight. The liquid content may be 1% to 10% by weight. The liquid content may be 1.5% to 8% by weight. The liquid content may be 1.8% to 6.5% by weight. The liquid content may be 2% to 5% by weight. The increasingly narrower ranges of liquid contents may be increasingly beneficial for the properties of the fiber-based industrial material. In particular, the fiber-based industrial material may have a water content of 1% to 15% by weight. The water content may, in particular, be 1% to 10% by weight. The water content may, in particular, be 1.5% to 8% by weight. The water content may, in particular, be 1.8% to 6.5% by weight. The water content may, in particular, be 2% to 5% by weight. The dried fiber-based industrial material may be subjected to an additional step of pressing (as described above) to increase the density of the final material, resulting in a high-strength board-like material. In this context, the pressed fiber-based industrial material may have a density of from 200 to 1200 kg / m, or from 400 to 1200 kg / m, or from 600 to 1200 kg / m, or from 800 to 1200 kg / m. 2.4 Processing The preparing step may comprise processing a liquid slurry or a foam and fibers into the fibrous foam. In other words, a liquid slurry and solids, such as fibers, or a foam and solids, such as fibers, may be processed into the fibrous foam. The processing may at least partially be performed by a transporting means that transports the fibrous foam to a forming means that forms the fibrous foam into the foam layer. This may offer the benefit of a more space-efficient manufacturing process and may also promote procedural efficiency. When at least a part of the processing is performed by the transporting means, there is no need to provide additional separate devices for the same part of the processing. According to some embodiments, the processing may be performed by the transporting means. This may particularly promote being able to perform the manufacturing in a space-efficient manner. Uniting processing and transporting allows for an integral carrying out of the steps, for example, with a single structural unit. This may in turn also allow for higher processing speeds, as the same procedural step may promote both processing as well as transportation. The melting together of those steps may also lower the specific energy consumption, as the same movements may be used to promote different aims in parallel. The apparatus may comprise a pressurization device between the transportation means and the forming means. The processing may be performed by a processing means and the draining of the fibrous foam may be performed by a draining means. One or several of the following components may be part of one integral structural unit: the preparation means, the processing means, the transporting means, the forming means, and the draining means. The integral structural unit may comprise any two or any three or all of the listed means. The processing means may comprise the transporting means. The processing means and the transporting means may be one and the same structural unit. This may promote space efficiency regarding the equipment. Moreover, the integral construction may also promote higher processing speed and / or lower specific energy consumption. The integral construction means that the means belong to one and the same structural unit, rather than being provided in separate structural units. This may promote space efficiency of the manufacturing equipment. Moreover, the integral construction may allow for a finetuned matching of manufacturing steps that follow upon one another, so that the manufacturing time may be reduced. The processing may comprise increasing a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation. The increasing of pressure may be effected by changing the speed of transportation (e.g., by subsequently increasing and lowering the transportation velocity, or vice versa). The increasing or decreasing of the pressure may, e.g., be an increase of at least 0.1 bar. It may be up to 10 bars. It may be in a range of 0.1 bar to 8 bars, or 0.5 bar to 6 bars. The pressure may be increased once or several times. The pressure may be decreased once or several times. The pressure may be increased and decreased once or several times. The pressure increases and / or decreases may contribute to changing the properties of the foam being processed. The processing may comprise successively applying a plurality of different pressure levels in the downstream direction, wherein the pressure level may be decreased twice or more and / or the pressure level may be increased twice or more. The increasing of the pressure may comprise successively applying a plurality of different pressure levels in the downstream direction, the pressure levels being increased at least twice. The processing and / or transporting may comprise at least one of: exerting shear forces, exerting elongation forces, mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives. The above may be achieved by exerting shear forces, elongational forces, and mixing, in particular by exerting elongational forces. The fiber volume fraction in the fibrous foam may be controlled in particular by choosing a consistency of one or several types of fibers in the fibrous foam and the air content in the fibrous foam. Adjusting the fiber volume fraction may be used to control properties of the fibrous foam, such as the viscosity and / or the rheology. The processing may in particular be used to decrease the fiber volume fraction. Alternatively, the processing may be carried out such that the fiber volume fraction stays more or less the same. Alternatively, the processing may be carried out to increase the fiber volume fraction. 2.5 Transporting The rotating of the at least one rotatable means may promote defiberizing at least a part, optionally all of the fibers and / or deflocculating at least a part of the fibers, optionally all of the fibers. This may be a particularly efficient use of energy to promote transportation and to at the same time also promote defiberizing and / or deflocculation. This may further promote energy-efficiency. The fibrous foam may be transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means. The method may comprise supplying to the fibrous foam, when transporting the fibrous foam through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and / or a liquid slurry; and - a solid, such as fibers, powder, and / or granulate. The liquid may, e.g., be derived from dispersing an additive in a medium. The one or more additives may comprise additive solution, liquid additives, and / or additive dispersion. The rotating of the at least one rotatable means comprises rotating a twin-screw, a single-screw, or a multiple-screw. The transporting of the fibrous foam by rotating the at least one rotatable means may comprise one or several of the following: accelerating the fibrous foam; decelerating the fibrous foam; and applying a shear and / or elongation force to the fibrous foam. The application of a shear and / or elongation force (or of different shear / elongation forces), and / or the accelerating or decelerating of the foam, may contribute to modifying foam properties, such as, in particular, viscosity and / or rheology. The rotating of the at least one rotatable means is performed in a screw assembly. The screw assembly may comprise a housing and the at least one screw (as an example of a rotatable means). A minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 0.2% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm. The outer diameter of the screw, at a particular position of the screw along its rotational axis, is to be understood to be the diameter of the surface that is swept by a section of the rotating screw in a direction perpendicular to the rotational axis. This outer diameter of the screw may also be referred to as the flight diameter, the major diameter, or the diameter of a surface of revolution of the screw. The outer diameter of the screw may vary along the direction of its rotational axis or it may remain constant. An example of a screw with a varying outer diameter is a conical screw. The minimum distance referred to, is the minimum distance amongst all minimum distances at different positions along the rotational axis of a screw. The outer diameter of the screw may be in a range of from 1.5 mm to 2000 mm, or from 2 mm to 1500 mm, or from 4 mm to 1000 mm, or from 5 mm to 800 mm, or from 8 mm to 700 mm, or from 12 mm to 500 mm, or from 15 mm to 400 mm, or from 18 mm to 350 mm, or from 20 mm to 300 mm, or from 20 mm to 250 mm, or from 20 mm to 200 mm, or from 20 mm to 150 mm, or from 20 mm to 120 mm, or from 20 mm to 110 mm, or from 20 mm to 100 mm. The at least one rotatable means may comprise at least a first screw and a second screw. The first screw and the second screw may be independently rotatable, or rotatable together, or, in some embodiments, alternatively independently or commonly rotatable. A distance of closest approach between the first screw and the second screw during rotations may be in the range of from 0.3 mm to 20 mm. The distance of closest approach may be in a range of from 0.35 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm. The first screw and the second screw may be intermeshing or they may be non-intermeshing. The outer diameter of the first screw may be constant along its rotational axis or it may vary along the rotational axis. In addition, the closest approach between the first screw and the housing may be constant or it may vary along the rotational axis. Likewise, the outer diameter of the second screw may be constant along its rotational axis or it may vary along the rotational axis. In addition, the closest approach between the second screw and the housing may be constant or it may vary along the rotational axis. The term closest approach between a screw and the housing refers to the distance between a sweeping surface of the outer diameter of the respective screw and the opposing surface of the housing. The distance of closest approach refers to the smallest distance amongst all the distances along the respective rotational axis. The term closest approach between two screws refers to the minimum distance between the two screws reached when the screws are being rotated. The at least one rotatable means may comprise a plurality of screws and at least one housing that houses the plurality of screws. A distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw may be in the range of from 0.3 mm to 20 mm. The distance of closest approach may be in a range of from 0.35 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm. Prior to the forming, the fibrous foam may be displaced by a displacement pump. The fibrous foam may also be displaced by two or more displacement pumps, in particular positive displacement pumps. Each of the displacement pumps (or, if there is a single one, the one displacement pump) may be a of rotary or of reciprocating type. A positive displacement pump may develop high pressures while operating at low suction pressures. The displacement by one or several displacement pumps may be combined with other types of displacement. 2.6 Controlling The method may be controlled may, to this end, comprise one or several control units. The dispersing of the gas in the liquid may be performed using a feedback loop control. The feedback loop control may include measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value. The feedback loop control may include measuring and controlling one, two, or three of the mentioned parameters. In addition, or alternatively thereto, the feedback loop control may include measuring and controlling one or several different parameters. The target value for the gas content may be set in a range of 70% or more by volume, or 75%, or 80%, or 85%, or 90% or more by volume of the gas-liquid dispersion. The target value for the density may be set in a range of from 200 to 1200 kg / m3, or from 250 to 1100 kg / m3, or from 300 to 1000 kg / m3, or from 350 to 950 kg / m3, or from 400 to 9005 kg / m3, or from 450 to 850 kg / m3. The target value for the conductivity may be set in a range of 0 to 5000 µS / cm, or 100 to 4000 µS / cm, or 500 to 3500 µS / cm, or 1000 to 3000 µS / cm. The preparing may comprise supplying the gas and the liquid into a vessel such that a volume ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value. The predetermined volume ratio may be in a range of from 0.002 to 0.55, or from 0.005 to 0.43, or from 0.01 to 0.33, or from 0.018 to 0.25, or from 0.025 to 0.18, or from 0.033 to 0.14. The preparing may comprise supplying the gas and the liquid into a vessel such that a density of the gas-liquid dispersion lies in a predetermined range or amounts to a predetermined value. The predetermined range may be set to be in a range of from 3 to 550 kg / m3, or from 10 to 355 kg / m3, or from 18 to 300 kg / m3, or from 37 to 180 kg / m3, or from 40 to 145 kg / m3, or from 45 to 143 kg / m3, or from 48 to 143 kg / m3, or from 50 to 142 kg / m3, or from 50 to 140 kg / m3. The preparing may comprise mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and / or a gas content reaches a predetermined minimum threshold. The predetermined minimum threshold for the foam heigh may be set in accordance with the geometry of the fibrous foam preparation means. The predetermined minimum threshold for the gas content may be set to be at least 70%, or 75%, 80%, or 85%, or 90%, or 93%, or 95%, or 96% by volume. 2.7 Manufacturing of end material This disclosure also relates to the manufacturing of an end material or product, wherein the manufacturing comprises the steps of manufacturing a fiber-based industrial material in accordance with any one or several of the aspects described in this disclosure. The manufacturing of the end material or product may comprise winding up a manufactured fiber-based industrial material. The manufacturing of the end material or product may comprise confectioning a manufactured fiber-based industrial material, on its own, or combined with one or several further materials and / or products. Confectioning may comprise any one or several of the following operations which may be considered part of a manufacturing process, such as folding, laminating, printing, coating, embossing. The manufacturing of the end material or product may comprise converting a manufactured fiber-based industrial material into a packaged or an unpackaged end product. A packaged end material or product may, e.g., comprise or consist of a product that has been packaged in a plastic wrapping or packaging, or in another type of wrapping or packaging. The end material may a single fiber-based industrial material layer or a multilayer material comprising at least one manufactured fiber-based industrial material layer. An end material may be a multilayer material comprising one or several manufactured fiber-based industrial material layers, wherein two or more layers of the multilayer material may be identical or mutually different. The single layer or multilayer end material may be rolled, or folded, or stacked, stapled, or grouped in another way. 3. Fiber-based industrial material This disclosure also relates to a fiber-based industrial material that is manufacturable by the method in accordance with one or several of the aspects of the method described above. An aspect may be one or several features and, in particular, a combination of features as discussed. In particular, this disclosure also relates to a fiber-based industrial material that is manufactured by the method in accordance with one or several of the aspects of the method described above. The manufacturable fiber-based industrial material may have a basis weight of 50 to 800 g / m and a density of 200 to 1200 kg / m.A variation σ of the basis weight measured in accordance withSCAN-P 92:09 may be less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basisweight of the fiber-based industrial material. The variation σof the basis weight can be determined by beta-formation analysis. The beta-formation analysis principle is based on the decay ofthe C-atom, emitting electron, antineutrino and resultingnitrogen (N). Briefly, the test sample is placed on top of a radiation source ( C, activity 1.18 GBq), and electrons penetrating the test sample are measured with an imaging plate (BAS IP-MS 2325). This is possible as the energy of the electrons is continuous from 0 to decay maximum energy E . The measured current of the electrons is the lower, the more there is material between the radiation source and imaging plate. The radiation map of the electrons in the imaging plate is read with reader (BAS 1800 II 4046) and converted to basis weight map with Matlab. The result is a small-scale basis weight map of the sample. The pixel size is 1mm*1mm. A suitable instrument for performing the beta-formation analysis is the Ambertec Bety Formation Tester (available from Ambertec Oy, Finland). The fiber-based industrial material may comprise at least 50 wt.-% or at least 55 wt.-% or at least 60 wt.-% or at least 65 wt.-% or at least 70 wt.-% of fiber material based on the total weight of the fiber-based industrial material. The fiber-based industrial material may have a basis weight of 50 to 800 g / m and a density of 200 to 1200 kg / m. The basis weight is in this context determined by the standard DIN / ISO 12625-6. This may in particular sufficient strength for the material that in turn provides the basis for a sufficient strength for an industrial material. The fiber-based industrial material may have a thickness in a range of from 0.02mm to 80mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may have an upper side and a lower side, and a density in a central region of the material located between the upper and lower sides in a thickness direction may be lower than a density in a region of the fiber- based industrial material located at the lower and / or upper side(s). The fiber-based industrial material may comprise a surface active agent. The presence of the surface active agent may allow verifying whether the product has been manufactured in accordance with some of the embodiments of the method of the present disclosure. The fiber-based industrial material may comprise one, two, three, four or five of the following: (a) at least 0.5 wt.-% of one or more binders, (b) at least 0.05 wt.-% of one or more rheology modifiers, (c) at least 0.01 wt.-% of one or more surface active agents, (d) at least 0.2 wt.-% of one or more slipping agents, and (e) at least 0.5 wt.-% of one or more fillers, each based on the total weight of the fiber-based industrial material. The remainder may comprise or consist of fibers. In one aspect, the present disclosure also relates to a multilayer material, e.g., a material comprising two. three, four, five or six layers, which comprises at least one layer that is made of the fiber-based industrial material manufacturable by the method in accordance with one or several of the aspects of the method described above. The multilayer material may further comprise at least one layer of another type, such as a conventional wet press layer, a molded layer, a structured layer, or the like. In another aspect, the present disclosure relates to a multilayer material, e.g., a material comprising two, three, four, five or six layers, which comprises at least one layer that is made of a fiber-based industrial material having a basis weight of 100 to 2000 g / m and a density of 10 to 200 kg / m. The multilayer material may further comprise at least one layer of another type, such as a conventional wet press layer, a molded layer, a structured layer, or the like. The fiber-based industrial material may be a material selected from the group consisting of (thermal and / or sound) insulation materials, (flexible) packaging materials, paperboard materials, filtration materials, thermoformable non-hygienic composites, non-hygienic mouldable materials, technical textiles, and / or abrasive paper materials. In particular, the fiber-based industrial material may be an insulation material. The insulation material may be a sound and / or thermal insulation material. Sound insulation materials are designed to reduce or block the transmission of sound from one area to another. They are commonly used in various settings, including residential buildings, commercial spaces, industrial facilities, and transportation infrastructure. The fiber-based industrial material may be used as such, or combined with other materials to create structures, e.g., consisting of multiple layers and materials, which work together to absorb, reflect, or dampen sound waves, preventing them from passing through. Typical sound insulation structures can involve mass, decoupling, adsorption or damping effects. Mass is a fundamental element in sound insulation. Heavier materials are more effective at blocking sound than lighter ones. Sound insulation can involve separation between two structures or surfaces to minimize sound transmission. This can be achieved through techniques like adding resilient channels or isolators to prevent direct contact between materials. The fiber-based industrial material may be used as a sound- absorbing material to reduce sound reflections within a space. The material may include acoustic panels, fiberglass, mineral wool, and foam. The material may dissipate sound energy or convert it into heat. The material may be of class A, B or C according to BS EN ISO 354. The fiber-based industrial material may also be used as a damping material to reduce vibrations and resonance that can carry sound through structures. Such material is often added to walls or floors to reduce the transmission of impact noise. Thermal insulation structures play a crucial role in reducing energy consumption and maintaining comfortable indoor environments. Properly designed and installed insulation helps save energy, reduce utility costs, and minimize the environmental impact of heating and cooling systems. Insulation materials are the core components of thermal insulation structures. These materials are selected for their ability to resist the transfer of heat. The fiber-based industrial material may be used as such, or combined with other materials such as fiberglass, cellulose, foam boards, spray foam, mineral wool to create thermal insulation structures. The thermal conductivity of the fiber-based industrial material may be less than 0.06W / (m·K) (watts per meter times kelvin), or less than 0.04W / (m·K). For sound and / or thermal insulation purposes, it may be desirable that the fiber-based industrial material has a basis weight of 50 to 800 g / m, or 100 to 500 g / m, or 150 to 400 g / m, and a density of 200 to 400 kg / m, or 200 to 300 kg / m, or 200 to 250 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For sound and / or thermal insulation purposes, the thickness of the fiber-based industrial material may be in a range of from 0.2mm to 250mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be a packaging material, in particular a flexible packaging material. Flexible packaging materials are a category of materials used for packaging products that require a lightweight, versatile, and often resealable solution. These materials are designed to provide protection, preservation, and convenience for various products, in particular for food and beverages. Flexible packaging materials offer several advantages, including being cost-effective, customizable, and environmentally friendly. For flexible packaging purposes, it may be desirable that the fiber-based industrial material has a basis weight of 50 to 500 g / m, or 50 to 300 g / m, and a density of 200 to 1200 kg / m, or 300 to 1200 kg / m, or 500 to 1200 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For these purposes, the thickness of the fiber-based industrial material may be in a range of from 0.02mm to 5mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be a paperboard. Paperboard is a versatile and rigid paper-based material commonly used in packaging, printing, and graphic arts. It is thicker and sturdier than regular paper but thinner than corrugated cardboard. Paperboard is valued for its smooth surface, printability, and foldability. There are different types and grades of paperboard, each tailored for specific applications to be used, e.g., in folding cartons, book covers, custom packaging, product packaging inserts. For paperboard purposes, it may be desirable that the fiber- based industrial material has a basis weight of 50 to 800 g / m, or 100 to 700 g / m, or 120 to 600 g / m, and a density of 200 to 1200 kg / m, or 300 to 1200 kg / m, or 500 to 1200 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For paperboard purposes, the thickness of the fiber-based industrial material may be in a range of from 0.1mm to 5mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be a filtration material. Filtration materials are substances or structures used to separate solids from liquids or gases, or to remove impurities and contaminants from a fluid. Filtration is a fundamental process used in a wide range of industries, including water treatment, air purification, chemical processing, pharmaceuticals, food and beverage production, and more. The fiber-based industrial material may be used to trap solids as a fluid passes through it. It may be designed with specific pore sizes to meet the desired application and achieve efficient filtration. For filtration purposes, in particular package cushioning purposes, it may be desirable that the fiber-based industrial material has a basis weight of 100 to 200 g / m and a density of 200 to 400 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For filtration purposes, the thickness of the fiber-based industrial material may be in a range of from 0.2mm to 5mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be a thermoformable composite material. Thermoformable composite materials, also known as thermoplastic composites, are advanced materials used in various industries for their lightweight, strong, and moldable properties. They are often used in applications where both strength and the ability to be formed into complex shapes are required. Thermoformable composite materials can be shaped into complex forms through processes like thermoforming, compression molding, or vacuum bagging. This allows for the production of intricate and lightweight components. Furthermore, thermoformable composites may exhibit excellent impact resistance, making them suitable for applications where durability and the ability to withstand sudden forces are required. When the fiber-based industrial material is a thermoformable composite, it may be desirable that the material has a basis weight of 300 to 800 g / m and a density of 200 to 1200 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For these purposes, the thickness of the fiber-based industrial material may be in a range of from 0.1mm to 15mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be a technical textile. Technical textiles, also known as engineered or industrial textiles, are specialized textile materials and products designed for specific technical and functional purposes, rather than for their aesthetic or decorative properties. These textiles are engineered to provide particular performance characteristics or functionalities, making them essential components in various industries and applications. Technical textiles are known for their versatility, durability, and advanced properties. In one aspect, the fiber-based industrial material may be a technical textile as set out above, which is selected from: - Agrotech textiles, i.e., used in agriculture for applications such as crop protection, greenhouse coverings, shade nets, and geotextiles used in soil erosion control; - Hometech Textiles, i.e., upholstery fabrics, carpet backings, and window shades, designed for their functional properties in home and interior applications; - Mobiltech textiles, i.e., used in the automotive, aerospace, and transportation industries for applications like seat belts, airbags, car interiors, and aircraft composites; - Oekotech textiles, i.e., used for environmental protection and sustainability purposes, including products like filters, waste containment materials, and biodegradable textiles; - Protech textiles, i.e., designed for protective purposes, such as bulletproof vests, flame-resistant clothing, chemical-resistant suits, and safety harnesses; - Sportech textiles, i.e., used in sport and outdoor applications, including sportswear, outdoor gear, and specialized materials for sports equipment; - Buildtech textiles, i.e., geotextiles used in civil engineering projects, construction materials like scaffolding nets, and architectural textiles for tension structures; - Geotech textiles, i.e., used for soil and environmental engineering purposes, such as erosion control, reinforcement, and filtration; - Meditextiles, i.e., designed for applications in the mattress and bedding industry, including mattress components, mattress ticking, and bed linens; - Clothtech textiles, i.e., used in the textile and clothing industry for specialized applications, such as fabrics with conductive properties for electronic textiles and smart clothing; - Indutech textiles, i.e., used in the industrial sector for applications like conveyor belts, filtration materials, insulation, and composite materials; - Produtech textiles, i.e., used to serve the food and agricultural industries and include products such as food packaging materials and food filtration textiles. The fiber-based industrial material may be a non-hygienic mouldable material or a molded pulp (fiber) material. Moldable materials are substances that can be shaped, molded, or formed into a variety of shapes or configurations when exposed to heat, pressure, or other shaping methods. These materials are often used in manufacturing and various industries for creating custom components, prototypes, and finished products. The choice of moldable material depends on the specific application and the desired properties of the final material. Molded pulp materials (or molded fiber materials) are packaging materials used for protective packaging, or for food service trays and beverage carriers. Other typical uses are end caps, trays, plates, bowls and clamshell containers. There can be made as dry molded fiber, slush molded, transfer molded or thermoformed. When the fiber-based industrial material is a non-hygienic mouldable material or a molded pulp (fiber) material, it may be desirable that the material has a basis weight of 50 to 800 g / m, or 100 to 800 g / m, and a density of 200 to 1200 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For these purposes, the thickness of the fiber-based industrial material may be in a range of from 0.05mm to 10mm. The thickness may be adapted, as needed, depending on the final purpose of the material. The fiber-based industrial material may be an abrasive paper material. Abrasive paper, also known as sandpaper, is a type of abrasive material used for various surface preparation and finishing tasks. It consists of a flexible paper or cloth backing onto which abrasive particles are securely bonded. Abrasive paper is available in a wide range of grit sizes, making it suitable for tasks ranging from coarse material removal to fine polishing and finishing. The abrasive paper may comprise abrasive particles, such as aluminum oxide, silicon carbide, or other materials that may be adhered to the paper or cloth backing using adhesives or resin. The abrasive paper material may have a grit size of 40 to 60 (coarser grit used for heavy material removal), or 400 to 600 (finer grit used for smoothing and polishing). The backing of the abrasive paper may be made of a fiber-based material in accordance with this disclosure, or a fiber-based material combined with paper and / or cloth. When the fiber-based material is combined with cloth, the abrasive paper is more durable and tear-resistant, making it suitable for heavy- duty applications. When the fiber-based industrial material is an abrasive paper material, it may be desirable that the material has a basis weight of 80 to 200 g / m and a density of 300 to 1200 kg / m. The basis weight and / or density may be adapted, as needed, depending on the final purpose of the material. For these purposes, the thickness of the fiber-based industrial material may be in a range of from 0.05mm to 2mm. The thickness may be adapted, as needed, depending on the final purpose of the material. 4. Apparatus for manufacturing a fiber-based industrial material This disclosure also relates to an apparatus for manufacturing a fiber-based industrial material. 4.1 Fibrous foam preparation means The apparatus may comprise a fibrous foam preparation means preparing a fibrous foam. The fibrous foam preparation means may comprise a supply means that supplies (or is configured to supply) solids, one or more surface active agents, a liquid, and gas, wherein a solids content is 5% to 60% by weight, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume. The liquid may be water or it may comprise water. The gas may be air or it may comprise air. The supply means may supply (or be configured to supply) liquid comprising at least 95% water by weight, and / or gas comprising at least 95% air by volume. The fibrous foam preparation means may comprise a solids supply means that supplies solids, wherein a solids content may be 5% to 60% by weight, weight or 10% to 60% by weight or 15% to 60% by weight, and wherein at least 80% by weight of the solids may be fibers. At least 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers. All of the solids may be fibers. The fibrous foam preparation means may prepare (or may be configured to prepare) the fibrous foam with a solids content, wherein a solids volume fraction may be 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content may be a fiber content. The liquid may comprise at least 95% by weight of water. Alternatively, the liquid may comprise at least 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% by weight of water. The use of significant amounts of water as the liquid may promote cost efficiency. A fiber content may be 5% to 60% by weight. A liquid content may be 40% to 95% by weight. A gas content may be 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume. The gas may comprise at least 95% air by volume. Alternatively, the gas may comprise at least 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% of air by volume. The use of significant amounts of air as the gas may promote cost efficiency. The fibrous foam preparation means may prepare (or be configured to prepare) the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less. The liquid may be water or it may comprise water. The gas may be air or it may comprise air. The apparatus may comprise a slurry preparation device that prepares (that is configured to prepare) an intermediate mixture / slurry foam / slurry solution comprising at least one component selected from the group consisting of: liquid, such as water, fibers, one or more surface active agents, one or more binders, and one or more slipping agents. The apparatus may comprise a surface active agent supply means that supplies (or is configured to supply) at least one surface active agent or a mixture of surface active agents. The surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, and nonionic surface active agents. The fibrous foam preparation means may transport (or be configured to transport) the fibrous foam to the formation means. The fibrous foam preparation means may promote (or may be configured to promote) preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means by the same mechanical movement. This may particularly promote process efficiency and / or allow lowering the specific energy consumption. The apparatus may comprise a high consistency mixing apparatus. The high consistency mixing apparatus may be comprised by the transporting means and may be a part of the same structural unit as the transporting means, the processing means, and / or the fibrous foam formation means. 4.2 Fibrous foam formation means The apparatus may comprise a foam layer formation means forming (or configured to form) the fibrous foam into a foam layer. The foam layer formation means may bring (or be configured to bring) the fibrous foam into a planar form. A foam layer has two dimensions of extension (two directions of a planar surface) and a dimension of thickness, wherein the foam layer is thin in the dimension of thickness as compared to the dimensions of planar extension. The form of a foam layer may be beneficial in terms of allowing draining, in particular, mechanical draining, but also allowing (thermal) drying. Moreover, the foam layer may be considered a step towards the desired form of a fiber-based industrial material, such as a fiber-based insulation, packaging,filtration, construction, thermoformable composite and / or growthmedia material. The foam layer formation means may bring (or be configured to bring) the fibrous foam into a planar layer. The planar form may allow for an efficient draining (in particular, for a dewatering). The bringing the fibrous foam into a planar layer may alternatively also be referred to as forming the fibrous foam into a planar layer. The apparatus may comprise a die and / or a headbox and / or a cylindrical mold that may at least in part perform (or be configured to perform) the forming. The die and / or headbox may comprise at least one foam shaping part (a flow part) over which a fibrous foam flows, in order to be brought into a planar form. In particular, a die and / or a headbox and / or a cylindrical mold may be shaped as to bring the foam into a form with a ratio of 8 or more between a length in the MD (machine direction) direction and a length in the CD direction (cross machine direction). The ratio may be 2 or more, 4 or more, 6 or more, 9 or more, or 10 or more, or 11, or 12, or 13 or more. The die and / or headbox may comprise two or more foam shaping parts. The die and / or headbox may comprise an outlet height of at least 0.5 mm, or at least 0.8 mm, 0.9 mm, or 1.0 mm. These minimum heights, to an increasing degree with increasing minimum height, may be suitable to prevent or even avoid clogging. The outlet height may be a slit opening. The outlet height may be in a range from 0.5 mm to 100 mm, from 1.0 mm to 80 mm, from 2 mm to 70 mm, from 5 mm to 50 mm, or from 2.5 mm to 25 mm, such as about 10 mm. An inlet height may be at least 1.5, 2.0, 3.0, 5.0, or 8.0 times larger than the outlet height. The outlet height, or, more generally, the opening size (e.g., a size of an outlet surface cross-section) may be adapted to a desired foam consistency or product. The foam consistency, the fiber volume fraction, and / or the air content may be adapted to achieve a desired target basis weight of the foam layer. In addition, also the solids volume fraction in general, and, in particular, the fiber volume fraction may be tailored to the desired basis weight and / or density. The die and / or headbox may comprise a lateral spread-out part that is shaped as to promote a lateral spreading out of foam, in order to increase the ratio of the MD / CD dimension of the foam. 4.3 Draining means (e.g., dewatering means) and drying means The apparatus may comprise a draining means draining (or configured to drain) the fibrous foam in the foam layer to form a fibrous web or sheet having a liquid content of 20% to 85% by weight (or a solids content of 15% to 80% by weight). The liquid content of 20% to 85% of the fibrous web or sheet may be considered a remarkably low liquid content as a starting point for a drying means to subsequently perform a drying process. The apparatus may have a lower specific energy consumption, as compared to an apparatus used in the course of conventional hygiene paper making processes. For example, the liquid content at the end of the draining step may be half of the liquid content encountered in comparable manufacturing methods prior to a drying step. This may allow using less energy as compared to a comparable manufacturing apparatus relying on conventional mold or wet manufacturing. The draining means may comprise a mechanical draining means, such as a pressing means. Mechanical draining relies on the use of mechanical force to remove liquid. When the liquid is or comprises water (or substantially water), the mechanical draining can also be referred to as mechanical dewatering. The draining means may be a dewatering means. The mechanical draining means may be a mechanical dewatering means. Mechanical dewatering relies on the use of mechanical force to remove water. The mechanical draining may allow for a reduction of liquid content and, hence, promote the apparatus having a lower specific energy consumption, in particular associated with the thermal drying (in particular, thermal dewatering). This may promote energy savings and, hence, promote environment friendliness. The draining means may consist of a mechanical draining means. It may comprise or consist of a mechanical dewatering means. The dewatering is in this context be understood not to comprise drying, i.e., the dewatering is in this context to be considered separate from thermal draining (in particular, thermal dewatering) in the sense of drying. The apparatus may comprise a drying means that dries (or is configured to dry) the fibrous web to obtain a fiber-based industrial material. The specific energy consumption associated with subsequent drying may be lower than when using conventional manufacturing processes. This in turn may be associated with lower liquid contents of the fibrous web as compared to known intermediate products. Moreover, the drying may bring down the liquid content to the level needed for an industrial material. The drying means may comprise or consist of a thermal drying means. The drying means may comprise or consist of a freeze drying means. The drying means may comprise or consist of an infrared drying means. The drying means may comprise or consist of a contact drying means. The drying means may comprise or consist of an impingement drying means. The drying means may comprise or consist of a microwave drying means. The drying means may comprise or consist of a through air drying (TAD) drying means. The drying means may comprise or consists of any combination of the mentioned types of drying means (including one or several drying means of a particular type). The drying means may, in particular, be considered a thermal drying means, as opposed to a mechanical draining means. The drying means may perform (or be configured to perform) the drying, and the fiber-based industrial material obtained may have a liquid content of 0.5% to 15% by weight. The liquid content may be 1% to 10% by weight. The liquid content may be 1.5% to 8% by weight. The liquid content may be 1.8% to 6.5% by weight. The liquid content may be 2% to 5% by weight. The increasingly narrower ranges of liquid contents may be increasingly beneficial for achieving sufficient stability and strength and customer satisfaction. In particular, the fiber-based industrial material may have a water content of 0.5% to 15% by weight. The water content may, in particular, be 1% to 10% by weight. The water content may, in particular, be 1.5% to 8% by weight. The water content may, in particular, be 1.8% to 6.5% by weight. The water content may, in particular, be 2% to 5% by weight. The draining means may apply (or be configured to apply) a vacuum to the foam layer with a constant pressure or with a varying pressure. The variation may be a temporal or a spatial variation. In other words, the pressure may be increased or lowered as a function of time. In addition, or alternatively thereto, the pressure may be higher or lower up- and downstream (i.e., a spatial pressure variation). The draining means may comprise or consist of one or several vacuum boxes. The varying pressure may be a pressure that has at least one decrease in a downstream direction of transportation. The pressure may, e.g., be successively increased and decreased, re- increased, etc. The draining may successively apply (or be configured to successively apply), in some cases together with a control means, at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure. In-between these stages, the pressure may or may not be lowered. In other words, there may be several stages of increasing and decreasing the pressure. The draining means may apply (or be configured to apply) a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation. The draining means may apply (or be configured to apply) successive pressure increases and / or decreases, re- increases, etc. 4.4 Processing means The fibrous foam preparation means may comprise a processing means that processes (or is configured to process) a liquid slurry and / or a foam and solids, such as fibers, into the fibrous foam. The fibrous foam preparation means may comprise two or several processing means, wherein at least one of them may process (or be configured to process) a liquid slurry and fibers into the fibrous foam and another one of them may process (or be configured to process) a foam and fibers into the fibrous foam. The apparatus may further comprise one or several solids supply means supplying solids to the fibrous foam preparation means, and one or several liquid supply means supplying liquid to the fibrous foam preparation means, to form the fibrous foam with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam. The one or several liquid supply means may supply liquid at different stages of the preparing, i.e., sequentially at different points in time or space during the preparing process. In particular, the solids supply means and the liquid supply means may respectfully be dimensioned (and, in particular, relatively dimensioned) such that a fibrous foam with the desired (rheological) properties is obtained. In addition thereto, or alternatively, the apparatus may be provided with one or several control means that are configured to control the solids supply means and the liquid supply means such that a fibrous foam with the desired (rheological) properties is obtained. In addition, the one or several control means may be configured to control a gas supply means, such as, e.g., an air supply means. The fibrous foam preparation means may comprise a rheology modifier supply means that supplies (or is configured to supply) a rheology modifier. The rheology modifier(s) may be particularly useful in order to defiberize the fibrous material and / or achieve desirable rheological properties for forming. The fibrous foam preparation means may prepare (or may be configured to prepare) the fibrous foam to have a solids content of more than 5% by weight. The solids content may in particular involve a fiber content, and the fiber content may be more than 5% by weight (of the fibrous foam). The apparatus may comprise at least one rotatable means, and the apparatus may bring (or be configured to bring) one or several of a liquid slurry, a foam, solids, liquid, and the fibrous foam into contact with the at least one rotatable means and rotate (or be configured to rotate) the at least one rotatable means to transport the fibrous foam. The rotating of the at least one rotatable means may also process the fibrous foam or contribute to processing the fibrous foam. The same mechanical movement may be used particularly efficiently, as both transportation as well as processing and / or forming may be promoted by the same movements. The apparatus may rotate (or be configured to rotate) the at least one rotatable means with from 100 to 5000 revolutions per minute, or with 500 to 3000 revolutions per minute, or 800 to 2800 revolutions per minute, or 1000 to 2500 revolutions per minute, or 1600 to 2400 revolutions per minute. The rotatable means may be comprised by a high shear mixer, and the speed at which the mixer is run may be 100 rpm or more. The speed may be 200 rpm or more and 5000 rpm or less, or 200 rpm or more and 2000 rpm or less, or 200 rpm or more and 1000 rpm or less, or 200 rpm or more and 600 rpm or less. The rotating of the at least one screw may promote at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and heating, transporting, exerting pressure on, and building up pressure on the fibrous foam. The apparatus may comprise at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means. The apparatus may comprise a screw mixer. The screw mixer may, for example, be a conical screw mixer. The screw mixer may in particular by a transportation means, as described above. The screw mixer may, e.g., comprise the at least rotating means (in this case: a screw). The apparatus may comprise a fully automated foam generator that may produce foams, e.g., with densities between 50 and 1000 g / l. It may comprise a temperature controlled mixing head and may comprise a double action mechanical seal. It may further also be PLC-controlled with an automated air volume control and, e.g., a touchscreen. The screw mixer may, e.g., comprise an (e.g., gasket free) eccentric screw pump, e.g., with a temperature controlled storage tank. The apparatus may comprise a supply means that supplies (or is configured to supply), while the fibrous foam is prepared and / or processed and / or transported through the processing device (e.g., the extruder), at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and / or a liquid slurry; and - a solid, such as fibers, powder and / or granulate. The at least one rotating means may be a twin-screw, a single- screw, or a multiple-screw. The at least one rotating means may comprise one or several of the following sections: an acceleration section that accelerates (or is configured to accelerate) the fibrous foam being transported through the transporting means, such as, for example, an extruder, a mixer, or a kneader; a deceleration section that decelerates (or is configured to decelerate) the fibrous foam being transported through the transporting means; a shear and / or elongation application section that applies (or is configured to apply) a shear and / or elongation force to the fibrous foam. The apparatus may comprise a screw assembly that comprises a housing and the at least one rotatable means. A distance of closest between the at least one rotating means and an opposing inner surface of the housing may be in the range of 0.3 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm. The apparatus may comprise a displacement pump. The displacement pump may, for example, be a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, and the like, that, prior to the forming, displaces (or is configured to displace) the fibrous foam. The displacement pump may be comprised by a transportation means, as described above. The processing means may be provided in a controlled pressure chamber. The foam layer formation means may be provided in a controlled pressure chamber. The processing means and the foam layer formation means may be provided in the same controlled pressure chamber or in different controlled pressure chambers. 4.5 Transporting means The apparatus may comprise a transporting means that transports (or is configured to transport) the liquid slurry and / or the foam and / or the fibrous foam and / or solids, such as fibers, to the foam layer formation means. The processing means may comprise the transporting means, and the transporting means may perform at least a part of the processing. The transporting means may perform the processing. The processing means and the transporting means may be one and the same structural unit. Uniting the transporting and the processing, or, more generally, the transporting and the foam formation, at least partially or even fully, may promote space efficiency of the machinery needed for the manufacturing process. Moreover, uniting the different steps and performing them in integral multi-purpose devices may also promote processing speed (as one and the same step may at the same time promote more than one processing step) and may promote being able to lower the specific energy consumption. One or several of the following components may be part of one integral structural unit: the processing means, the fibrous foam preparation means, the transporting means, the forming means, a heating means, and the draining means. For example, two of the listed components may be a single unit, i.e., a structurally integral unit. Alternatively, any three of the listed components or all four of them may be a single unit, i.e., a structurally integral unit. This may allow for a particularly space-saving construction of the apparatus. Alternatively, or in addition thereto, it may allow for making use of differential functionalities of the same device simultaneously, which may promote production efficiency and / or energy efficiency of the apparatus. The transporting means may comprise a pressurization section that increases (or is configured to increase) a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation. The increasing of pressure may be effected by changing the speed of transportation (e.g., by subsequently increasing and lowering the transportation velocity, or vice versa). More generally, the pressurization section may increase (or be configured to increase) the pressure applied to the liquid slurry or the foam during transporting at least twice and / or decrease (or be configured to decrease) the pressure applied to the liquid slurry or the foam during transporting at least twice. The increasing or decreasing of the pressure may, e.g., be an increase or a decrease of at least 0.1 bar. The pressure may be increased several times. The pressure may be lowered once or several times. The pressure may be increased and decreased several times. The pressure increases and / or decreases may contribute to changing the properties of the foam being processed. In particular, the fibrous foam may comprise compressible compounds, as well as non-compressible compounds. Thus, the variations in pressure may change the fiber volume fraction of the fibrous foam and, hence, have an impact on its rheology. The pressurization section may successively apply (or be configured to successively apply) a plurality of different pressure levels in the downstream direction, the pressure levels being increased at least twice. The processing (or transporting) means may perform (or may be configured to perform) at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives. Any one or several of the listed types of processing may be used to adjust and control properties of the fibrous foam, such as the viscosity and / or the rheology. The fibrous foam may first be prepared to have a viscosity in the range of from 50 to 2000 Pa.s measured in accordance with the down-curve methodology at a shear rate of 0.01s (as described in section 2.f) below) and a storage modulus in the range of from 400 to 2500 Pa in the linear viscoelastic region (as described in section 2.f)). The fibrous foam may then be formed into a foam layer with a viscosity in the range of from 50 to 3000 Pa.s measured in accordance with the down-curve methodology at a shear rate of 0.01s (as described in section 2.f)) and a storage modulus in the range of from 500 to 10000 Pa in the linear viscoelastic region (as described in section 2.f)). The processing may in particular be used to lower the fiber volume fraction. Alternatively, the processing may be carried out such that the fiber volume fraction stays more or less the same. Alternatively, the processing may be carried out to increase the fiber volume fraction. 4.6 Control means The apparatus may comprise a temperature control means that controls (or is configured to control) a temperature inside at least one section of the apparatus. The apparatus may comprise a control device that controls (or is configured to control) the apparatus to perform the method in accordance with any one or several of the above-discussed method steps. 4.7 Manufacturing apparatus for end material This disclosure also relates to an apparatus for manufacturing an end material or product. The apparatus for manufacturing an end material or product may comprise an apparatus for manufacturing a fiber-based industrial material in accordance with any one or several of the aspects discussed above. The apparatus for manufacturing an end material or product may comprise any one or several of the following components: a web handling device, a winding device, a confectioning device, and a conversion device that converts into a packaged or unpackaged end material or product. In the following, the description is given with reference to the accompanying drawings, in which: Fig. 1A is a schematic view of an apparatus for manufacturing a fiber-based industrial material in accordance with an embodiment of the present disclosure; Fig. 1B is a schematic view of an embodiment of an apparatus for manufacturing a fiber-based industrial material in accordance with an embodiment of the present disclosure;Fig. 2 depicts an exemplary fibrous foam preparation means;Fig. 3A depicts a perspective view of a part of an exemplary foam layer formation means; Fig. 3B depicts the part of the exemplary foam layer formation means of Fig. 3A without an upper part of the cover so that a part of the inside is visible; Fig. 3C depicts a sectional side view of a die, as an example of a foam layer formation means; Fig. 4A depicts a sectional view of a twin-screw pump as an example of a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure; Fig. 4B depicts a sectional view of a lobe pump as an example of a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure; Fig. 5A is a perspective view of an extruder, as an example of a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure; Fig. 5B depicts the extruder of Fig. 5A, but with a part of the housing removed, to expose the interior; Fig. 6A depicts a part of a double screw of an extruder; Fig. 6B depicts a part of a double screw of an extruder exposed from its housing; Fig. 6C shows a sectional view of the double screw of Figs. 6A and 6B together with its housing; Fig. 7A depicts a part of another embodiment of an extruder comprising multiple screws located inside of their common housing; Fig. 7B depicts a part of an embodiment of an extruder comprising multiple screws located inside of their common housing;Fig. 8 depicts a draining means of an apparatus formanufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure;Fig. 9 depicts a drying means of an apparatus formanufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure; Fig. 10 depicts a web handling device of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure; Fig. 11 is a block diagram illustrating features of an embodiment of a method for manufacturing a fiber-based industrial material in accordance with the present disclosure; Fig. 12 is a graph illustrating the relationship between a fiber content of a fibrous foam and an air content of the fibrous foam; Fig. 13 is a graph illustrating the relationship between a solids content of a fibrous foam and an air content of the fibrous foam; Fig. 14 is a graph illustrating a correlation between at fiber volume fraction of a fibrous foam and a storage modulus G´ of the fibrous foam; Fig. 15 is a photo of a stress-controlled TA Instruments DHR- 2 rheometer equipped with a vane-in-cup geometry that was used to measure rheological properties of fibrous foam samples manufactured in accordance with the present disclosure; Fig. 16 depicts a cross-section through a layer of an embodiment of a fiber-based industrial material in accordance with the present disclosure; Fig. 17 depicts a cross-section through a multilayer product comprising an embodiment of a fiber-based industrial material in accordance with the present disclosure; Fig. 18 depicts a cross-section through a multilayer product comprising two layers in accordance with embodiments of a fiber-based industrial material in accordance with the present disclosure; Fig. 19 depicts a cross-section through a multilayer product comprising a foam formed layer in accordance with embodiments of a fiber-based industrial material of the present disclosure; Fig. 20 depicts a cross-section through a multilayer product comprising a foam formed layer in accordance with embodiments of a fiber-based industrial material of the present disclosure; Fig. 21 depicts a cross-section through a fiber-based industrial material in accordance with embodiments of the present disclosure. Fig. 1A depicts a schematic view of an apparatus 10 for manufacturing a fiber-based industrial material in accordance with an embodiment of the present disclosure. A method in accordance with an embodiment of the present disclosure may be carried out on this apparatus 10. The apparatus 10 of Fig. 1A comprises a fibrous foam preparation means 20 that prepares a fibrous foam. The fibrous foam preparation means 20 of Fig. 1A is a mixer. However, the mixer is an example only, and other embodiments may comprise a different fibrous foam preparation means. The fibrous foam preparation means may comprise or consist of one or several devices. The arrows laterally pointing towards the fibrous foam preparation means 20 represent a supply means 25 that may at least supply fibers, one or more surface active agents, a liquid, and gas to the fibrous foam preparation means 20. The supply means 25 comprises a solids supply means (symbolized by one of the lateral arrows) that supplies solids. For example, the solid supply means may supply a solids content of 5% to 60% by weight, and wherein at least 80% by weight of the solids are fibers. The supply means 25 also comprises one or several liquid supply means (symbolized by one or several of the lateral arrows) supplying liquid to the fibrous foam preparation means 20, to form the fibrous foam. A fibrous foam may, for example, be formed with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam. The supplied solids are dispersed in the solids-liquid dispersion that is to be prepared as a fibrous foam. The supply means 25 may comprise a rheology modifier supply means that supplies a rheology modifier. A fiber content of a fibrous foam prepared by the apparatus depicted in Fig. 1A may be 5% to 60% by weight, a surface active agents content may be 0.02% to 1.20% by weight, a liquid content may be 40% to 95% by weight, and a gas content may be 64% or more by volume. Narrower ranges that may be used for embodiments are defined above. The supply means 25 may supply liquid, in which the surface active agents, the fibers, and the gas (and, optionally, as well as other chemical components) are dispersed, comprising at least 80% by weight of water, and / or gas being dispersed in the liquid comprising at least 95% air by volume. The fibrous foam may, for example, be prepared such that it has a fiber volume fraction of 0.040 or less. Optionally, narrower ranges for the fiber volume fraction are associated with embodiments, as discussed above. More generally, the fibrous foam may be prepared to have a solids content with a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content is the fiber content. The fibrous foam preparation means 20 may prepare a gas-liquid dispersion that comprises a liquid content of at least 80% by weight of water, and / or a gas content of at least 95% air by volume. The transporting means 20 of Fig. 1A comprises a pressurization section that increases a pressure applied to the liquid slurry or the fibrous foam during the transporting in a downstream direction of transportation (the direction from left to right in the figure). The formed foam layer is then transferred to and conveyed with the permeable conveyor 40. The apparatus 10 of Fig. 1A further comprises a draining means 50 that drains the fibrous foam in the foam layer to form a fibrous web or sheet having a liquid content of 20% to 85% by weight. Moreover, the apparatus 10 of Fig. 1A comprises a drying means 60 that dries the fibrous web or sheet to form a fiber-based industrial material. The apparatus 10 of Fig. 1A also comprises a web handling device 70 comprising a winding device 72. The web handling device 70 removes a manufactured fiber-based industrial material from a conveyor section 71 and feeds it into the winding device 72. Fig. 1B schematically depicts an embodiment of an apparatus 10 for manufacturing a fiber-based industrial material. Figs. 1A and 1B are similar, and analogous components are denoted by the same reference numerals. A description of like components will not be repeated, but reference is instead made to the description of Fig. 1A. A difference between Figs. 1A and 1B is that the fibrous foam formation means / processing means / transportation means 20A of the embodiment of Fig. 1B is schematically depicted more specifically, namely, as a transportation means comprising a rotatable means that is rotatable by a motor 35. The apparatus 10 of Fig. 1B brings the liquid slurry and / or foam and / or fibrous foam being transported by the transporting means into contact with the rotatable means . More generally, as already described in the context of Fig. 1A, liquid, fibers (e.g., dry fibers), and chemical components such as a surface active agent are supplied to the fibrous foam formation means 20A, gas is supplied, and the solids are dispersed to prepare a liquid-gas dispersion that is used to prepare a fibrous foam. The rotatable means is rotated by the motor 35 to transport the fibrous foam. The revolution speed of the rotatable means is, depending on the embodiment, set within the range of from 100 to 5000 rpm (revolutions per minute). The rotating of the rotatable means by the motor 35 may at the same time, by the same mechanical movement, promote fibrous foam formation, processing, as well as transportation. The rotating of the rotatable means by the motor 35 may promote one or several of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and heating, transporting, exerting pressure on, and building up pressure on the fibrous foam. The foam layer formation means / processing means / transporting means 20 of Fig. 1A or the foam layer formation means / processing means / transporting means 20A of Fig. 1B may each be any one of the following: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin- screw machine, a mono- or twin-screw continuous kneader, a twin- screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means. The foam layer formation means / processing means / transporting means 20A of Fig. 1B comprises a housing that houses the rotatable means. A minimum distance (i.e., a minimum distance reached when considering all positions, in particular, all rotation positions of the rotatable means) between the rotatable means and an opposing inner surface of the housing is in the range of 0.3 to 20 mm. The transporting means 30A comprises a section that constitutes a foam layer formation means 33A that form the fibrous foam into a foam layer. The foam layer is then, analogously to what was described in the context of Fig. 1A provided to the permeable conveyor 40. The permeable conveyor 40 conveys the foam layer past the draining means 50 and the drying means 50. Fig. 2 depicts an exemplary fibrous foam formation means 20, namely, a mixer 20B in more detail. The mixer 20B may be used to prepare foam, and in the present case, it is used to prepare fibrous foam. The mixer 20B is an example of a processing means that processes a liquid slurry or a foam and fibers into the fibrous foam. The mixer 20B may be used to partially prepare a fibrous foam, and the preparation may then be continued in a fibrous foam formation means 20 as shown in Fig. 1A or in a fibrous foam formation means 20B as shown in Fig. 1B. In other words, in the case of some embodiments a part of the fibrous foam formation may already take place prior to the processing with the fibrous foam formation means / processing means / transporting means of embodiments as illustrated in Figs. 1A and 1B. In the case of other embodiments, the entire fibrous foam formation takes place in an integral fibrous foam formation means / processing means / transporting means (e.g., as shown in Figs. 1A and 1B). The mixer 20B comprises a rotor 21 that may be used to mix the supplied ingredients and thereby apply shear and / or elongation forces, defiberize the fibers, deflocculate, refine, disperse, disintegrate, change fiber shapes, and heat the slurry and / or foam (fibrous foam towards the end of the process), as well as heat the slurry or foam, while chemical additives are being added thereto. The mixer 20B comprises an input 23 for inputting chemicals and / or fibers, as well as an air input comprising a compressor 22 for compressing air to be supplied into the mixing chamber. After the mixing process, the mixer 20B outputs a fibrous foam to the pump 24 that may be, depending on the embodiment, the transportation means itself, or may pump the fibrous foam towards the transporting means 30. Fig. 3A depicts a perspective view of a part of exemplary foam layer formation means 33. This exemplary foam layer formation means 33 is a die 33B. The die 33B comprises an inlet 41, through which fibrous foam is fed into the die 33B, as well as an outlet 42. The die 33B forms the fibrous foam into a foam layer. The die 33B comprises an outlet 42 through which the foam layer exits the die 33B. Fig. 3A depicts the die 33B from the outside. The die 33B comprises a housing with an upper cover 43 and a lower cover 44 that together embed a hollow space which has a shape that is designed to form the fibrous foam being transported in a downstream direction into a planar shape, i.e., to form a foam Fig. 3B depicts the die 33B of Fig. 3A, but without the upper cover 43, so that a part of the inside (the hollow space) within the die 33B is visible. The space inside the die comprises a high but narrow potion 45 close to the inlet 41 where the fibrous foam starts to be broadened and flattened, and a shallow but broad portion 46 close to the outlet 42. In fact, there is, in the case of the depicted embodiments, a continuous transition of the geometry of the hollow space which promotes the shaping of the fibrous foam into an increasingly planar shape towards the downstream side of the foam stream. Fig. 3C depicts a sectional side view of the die 33B of Figs. 3A and 3B. In the view of Fig. 3C, it is easily visible that the height of the inner space (the hollow space in which the fibrous foam is being shaped) becomes increasingly narrower in the downstream direction (the direction from left to right in Fig. 3C). Fig. 4A depicts a sectional view of a twin-screw pump 30B as an example of a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure (the transportation means may also be the processing means and / or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure. The twin-screw pump 30B comprises a pump body 34 with an inlet 39 and an outlet 36. The pump body 34 houses a first screw 37A and a second screw 37B, together forming the twin-screw, as well as corresponding shafts 38A and 38B. Fig. 4B depicts a sectional view of a lobe pump 30C as an example of a positive displacement pump as a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure (the transportation means may also be the processing means and / or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure. The lobe pump 30C comprises a housing 38 with an outlet 36A and an inlet 39A, as well as two lobes 37C and 37D housed therein for displacing the fibrous foam. Fig. 5A is a perspective view of an extruder 30D, as an example of a transportation means of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure (the transportation means may also be the processing means and / or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure. Prior to reaching the extrude 30D, fibrous foam is prepared, and the extruder 30D then transports the fibrous foam in a downstream direction by rotating the extruder screw 32 that is located inside of the extruder housing 31. Fig. 5B shows the extruder 30D, but with a part of the housing removed, to expose the interior. As can be seen in Fig. 5B, the extruder 30D comprises an extruder screw 32. While the extruder 30D of Figs. 5A and 5B comprises a single extruder screw 32, other embodiments may comprise two or more screws. Fig. 6A shows a part of a double screw 32A (two extruder screws that operate together) within their common housing 31A. A distance of closest approach between the two screws of the double screw 32A is in the case of the embodiment shown around 1.25mm. However, in the case of other embodiments, the distance of closest approach may be different and, e.g., lie somewhere else within the range of from 0.3 mm to 20 mm. Fig. 6B shows the part of the double screw 32A in question without the housing 31A. Fig. 6C shows a sectional view of the double screw 32A of Figs. 6A and 6B together with its housing 31A. Fig. 7A depicts a part of another embodiment of an extruder comprising multiple screws 32B located inside of their common housing 31B. The housing 31B has a cylindrical shape, but this is just an example, as the shape of the housing may differ strongly from embodiment to embodiment. The multiple screws 32B are in the case of the embodiment of Fig. 7A arranged circumferentially around a central bearing unit 45. Also Fig. 7B depicts a part of an embodiment of an extruder comprising multiple screws 32C located inside of their common housing 31C. The housing 31C has a planar cuboid shape, as another example of a possible shape of a housing. The multiple screws 32C are in the case of this embodiment arranged adjacent to one another in a planar structure. Fig. 8 depicts a draining means 50 of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure. Prior to reaching the draining means 50, the fibrous foam has been formed into a foam layer L. The foam layer L is being conveyed in a downstream direction (the direction from left to right in Fig. 8, as indicated by the arrow pointing to the right). The draining means 50 comprises a vacuum station 51 that applies a vacuum to the foam layer L and in this way removes liquid (defluidizes, in particular, in the case of the illustrated embodiment: dewaters) it, to form a fibrous web having a liquid content of 20% to 85% by weight. The draining means 50 comprises a vacuum pump 52 for generating the vacuum used for dewatering the foam layer L. Fig. 9 depicts a drying means 60 of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure. Prior the step of drying carried out by the drying means 60, the fibrous web W is formed. It is then conveyed towards the drying means 60 that performs thermal drying, in order to further defluidize (in particular: dewater) the fibrous web W, in order to form a fiber-based industrial material in accordance with the present disclosure. Fig. 10 depicts a web handling device 70 of an apparatus for manufacturing a fiber-based industrial material in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure. The web handling device 70 comprises a winding device 72. The web handling device 70 removes a manufactured fiber-based industrial material from a conveyor section 71 and feeds it into the winding device 72. Fig. 11 is a block diagram illustrating features of an embodiment of a method for manufacturing a fiber-based industrial material in accordance with the present disclosure. In particular, Fig. 11 illustrates features of a method of controlling an apparatus for manufacturing the fiber-based industrial material. In order to carry out the preparing of the fibrous foam, the materials needed are supplied. This is symbolized by the supplying steps S0a and S0b, wherein step S0a, for example, relates to the supplying of water such that the water content is 40% to 95% by weight, fibers such that the fiber content is 5% to 60% by weight, and surface active agents such that surface active agents content of 0.02% to 1.20% by weight, and the step S0b relates to the supplying of air. There may of course be a large number of distinguishable supplying steps. Steps S0a and S0b are meant to be representative for the supplying only. In step S1, the fibrous foam is prepared, wherein the preparation includes dispersing the supplied fibers and the supplied one or more surface active agents in the supplied liquid, as well as dispersing gas in the liquid until a desired gas content (of 64% or more by volume is reached). For different embodiments, the desired gas content is set differently (it may, e.g., be set at 70%, 75%, 80%, 85%, 90%, or 95%, etc.). In steps S2, the air content is regularly (in some cases continuously, in other cases at intervals, etc.) measured, and the measured values are fed back to the control unit (step S3), and the control unit controls the preparation process, including, in particular, the mixing. The feedback loop also allows the control unit to modify the amounts supplied in the supplying steps S0a, S0b. When the measuring of the air content of step S2 indicates that the fibrous foam has the desired consistency, the fibrous foam is supplied to the transportation means in step S4. Fig. 12 is a graph illustrating the relationship between the fiber content (in weight %) of a fibrous foam and the air content (in weight %). In particular, Fig. 12 shows lines of constant fiber volume fraction. That is, the same fiber volume fraction can be achieved with different fiber contents by adjusting the corresponding air content, and vice versa. Fig. 13 is an analogous graph, this time showing the relationship between the solids volume fraction content (in weight %) of a fibrous foam and the air content (in volume %). That is, the solids volume fraction is based on all the solids included in the fibrous foam. The solids volume fraction may, for some embodiments, essentially be the fiber volume fraction, but for other embodiments, 99%, 98%, 97%, or less (e.g., 90%) of the solids may be fibers. That is, the solids volume fraction may be considered more general in this regard. Similarly to Fig. 12, Fig. 13 shows lines of constant solids volume fraction. That is, the same solids volume fraction can be achieved with different solids contents by adjusting the corresponding air content, and vice versa. Fig. 14 shows a graph illustrating the correlation between the fiber volume fraction of a fibrous foam (x axis) and the storage modulus G´ [Pa] measured at the strain amplitude of 0.025 % and angular frequency of 10 rad / s (y axis). The storage modulus G´ [Pa] represents the elastic component of the material stiffness. The storage modulus G´ [Pa] may be considered to represent the energy elastically stored in a material when it is deformed and that can then be reversibly released. The storage modulus G´ [Pa] is one of two components that make up the complex modulus G* (or complex modulus), which is a measure of the materials resistance to deformation, i.e., the overall stiffness of a viscoelastic material. The other component is the loss modulus, which represents the energy dissipated in the form of heat when a material undergoes deformation. The “storage modulus” or “elastic modulus” G´ is defined as: G' = G*cos(δ), The “loss modulus” or “viscous modulus” G´´ is defined as: G'' = G*sin(δ), wherein tanδ = G'' / G' is a measure of how elastic (tanδ < 1) or viscous (tanδ > 1) a material is. Fig. 15 is a photo of a stress-controlled TA Instruments DHR-2 rheometer equipped with a vane-in-cup geometry that was used to measure rheological properties of fibrous foam samples manufactured in accordance with the present disclosure (and using apparatuses in accordance with the present disclosure. Fig. 16 depicts a cross-section through a layer of an embodiment of a fiber-based industrial material 100 in accordance with the present disclosure. The material 100 of Fig. 16 is a single layer product that was made using the foam forming technology described herein. It comprises over 70 wt.-% of fiber material based in its total weight. Moreover, it has a basis weight of 100 to 2000 g / m and a density of 10 to 200 kg / m. The material 100 of Fig. 16 may comprise at least 0.5 wt.-% of one or more binders based on the total weight of the fiber-based industrial material. The material 100 of Fig. 16 may comprise at least 0.05 wt.-% of one or more rheology modifiers based on the total weight of the fiber-based industrial material. The material 100 of Fig. 16 may comprise at least 0.01 wt.-% of one or more surface active agents based on the total weight of the fiber-based industrial material. The material 100 of Fig. 16 may comprise at least 0.2 wt.-% of one or more slipping agents based on the total weight of the fiber-based industrial material. The material 100 of Fig. 16 may comprise at least 0.5 wt.-% of one or more fillers based on the total weight of the fiber-based industrial material. The material 100 was manufactured on the basis of embodiments of structural components and method steps described with reference to preceding figures. Fig. 17 depicts a cross-section through a multilayer material 110 comprising an embodiment of a fiber-based industrial material 111 in accordance with the present disclosure. The material 110 of Fig. 17 is a two layer material. The fiber-based industrial material 111 of the multilayer material 110 is the same as the material 100 depicted in Fig. 16, and the description thereof will not be repeated. The multilayer material 110 comprises a further layer 112. This additional layer 112 may be a layer manufactured by a conventional wet process or a structured layer. Fig. 18 depicts a cross-section through a multilayer material 120 comprising two layers 121 and 123 in accordance with embodiments of a fiber-based industrial material in accordance with the present disclosure. The material 120 of Fig. 18 is a three layer product. The layers 121 and 123 of the multilayer material 120 are the same as the layer constituting the material 100 depicted in Fig. 16, and the description thereof will not be repeated. The layers 121 and 123 may be the same or they may differ. The multilayer material 120 comprises a further layer 122. This additional layer 122 may be a layer manufactured by a conventional wet process or a structured layer. Alternatively, one foam formed layer may be combined with two or more further layers, or other selected numbers of foam formed layers may be combined with selected numbers of further layers, each of them being a layer made by a conventional wet process or a structured layer. The further layers may be the same or may differ. The foam formed layers may also be the same or may mutually differ. Fig. 19 depicts a cross-section through a multilayer material product 130 comprising a foam formed layer 131 in accordance with embodiments of a fiber-based industrial material of the present disclosure. The multilayer material 130 of Fig. 19 comprises a further layer 132, and the two layers 131 and 132 were laminated together. Prior to the lamination, the foam formed layer 131 was manufactured analogously as the material 100 depicted in Fig. 16. Fig. 20 depicts a cross-section through a multilayer material 140 comprising a foam formed layer 141 in accordance with embodiments of a fiber-based industrial material of the present disclosure. The multilayer material 140 of Fig. 20 is a three layer material comprising further layers 142 and 143. The three layers 141, 142, and 143 were laminated together. Prior to the lamination, the foam formed layer 141 was manufactured analogously as the material 100 depicted in Fig. 16. Fig. 21 shows a cross-section of a foam formed material manufactured according to the present disclosure at different density levels (as visualized with the Voreen software; sample details: CTMP60020% solids content, air content: 90%). EXAMPLES 1) Materials The main starting materials and chemicals used in the following examples are listed below: > Unrefined bleached softwood kraft pulp (SW / NBSK) from Mercer; > Bleached spruce chemithermomechanical pulp (CTMP600) from Rottneross (CFS=600; CFS: Canadian Standard Freeness); > Bleached spruce chemithermomechanical pulp (CTMP350) from Rottneross (CFS=350); > Simulsol SL10 (non-ionic surfactant) from Seppic (France) > Carboxymethyl cellulose MM8C (CMC, binder), medium viscosity, medium DS (0.6-0.9) from Lamberti. 2) Methods The following test methods were used to evaluate the web-based products produced. The test samples were conditioned for at least 12 hours at 50% relative humidity and 23 °C prior to testing. The following test methods were used to evaluate the fiber-based materials produced. The test samples were conditioned for at least 12 hours at 50% relative humidity and 23 °C prior to testing. a) Basis weight The basis weight was determined according to ISO 12625-6:2014. b) Thickness The measurement was made by a precision micrometer (precision 0.001 mm) according to a modified method based on EN ISO 12625- 3:2014, or EN ISO 534:2011 (for pressed samples). For this purpose, the distance created by a sample between a fixed reference plate and a parallel pressure foot is measured. The diameter of the pressure foot is 35,7 + 0.1 mm (10.0 cm2nominal area). The pressure applied is 2.0 kPa + 0.5 kPa. The pressure foot is movable at a speed rate of 2.0 + 0.4 mm / s. A usable apparatus is a thickness meter type L & W SE050 (available from Lorentzen & Wettre, Europe). The product to be measured is cut into pieces of 20 x 25 cm and conditioned in an atmosphere of 23°C, 50 % RH (Relative Humidity) for at least 12 hours. For the measurement one sheet is placed beneath the pressure plate which is then lowered. The thickness value for the sheet is then read off 5 seconds after the pressure has been stabilized. The thickness measurement is then repeated nine times with further samples treated in the same manner. The mean value of the 10 values obtained is taken as thickness of one sheet (“one-sheet caliper”) of the finished product measured. c) Density in g / cm3The density of the fiber-based material was calculated with the following formula: X = w / t X = density (g / cm3) w = basis weight of the sheets (g / m2) t = mean thickness of a sheet (µm) d) Foam density and air content The foam density and air content of the foam or fibrous foam was determined by placing the (fibrous) foam in a container of predetermined volume and weighing the container filled with the (fibrous) foam. In particular, the foam density (kg / m) and air content (%) were determined by comparing the measured foam weight to the weight of water of the same volume as the foam according to the following equations (1) and (2): ^^^^^^^^ ^^^^^^^^^^^^^^ = ^^^^^^^^ (^^)^^^^^^^^^^ (^^)× 1000 (in kg / m³) (1) 100 (in %) (2)e) Dry solids content The dry solids content of the fibrous foam was determined right after forming and dewatering. The test samples were weighted wet and after drying, and the dry solids content was calculated according to the following equation (3): 100 (in %) (3) wherein m is the dry mass of the sample and m is the wet mass of the sample. f) Rheology Rheological properties of the fibrous foam were measured with a stress-controlled TA Instruments DHR-2 rheometer equipped with a vane-in-cup geometry. The vane was a commercial 4-bladed vane geometry made out of stainless steel and having a diameter of 15 mm. The cup was 3D-printed by stereolithography and had a diameter of 30 mm. The outer wall of the cup was vertically profiled to eliminate wall slip during the rheologicalmeasurements (see Carraretto et al. Physics of Fluids 2022,43(11); Time-resolved rheometry of coarsening foams using three- dimensionally printed fractal vanes). The cup was placed in a temperature-controlled Peltier jacket that kept the temperature of the sample at 25 °C during all rheological measurements. Fiber foam samples were loaded into the cup with the help of a syringe whose end had been cut open, making sure that the whole cup was filled with fiber foam and that there were no air pockets inside the sample. The air content of the fibrous foam sample was determined by weighing the foam-filled cup before inserting it into the rheometer. Thereafter, the vane geometry was lowered into the sample so that the blades of the vane were located in the middle of the cup vertically (16 mm both from the bottom of the cup and from the upper surface of the foam sample). A picture of the vane-in-cup measurement setup is shown in Fig. XY. Three types of rheological measurements were performed for the fiber foam samples: 1) Amplitude sweep measurement from 0.01 to 100 % strainamplitude at a constant angular frequency of 10 rad / s 2) Frequency sweep measurement from 0.4 to 100 rad / s at astrain amplitude of 0.03 % 3) Shear rate sweep measurement first from the shear rateof 0.1 to 100 s-1 (“up-curve”) and then from the shear rate of 100 to 0.01 s (“down-curve”) f) Strength The strength properties of the manufactured materials were determined by the following methods: - Compression strength was determined in accordance with Standard EN826 (2013) using a Lloyd LR10K universal tester (Lloyd Instruments Ltd., UK) - Stress at 10% and 50% deformation, sample size 2 cm x 5 cm; - Z-directional strength was determined using a Lloyd LR10K universal tester - Samples cut in size of 2 cm × 5 cm. A double-side tape (Scotch 3M) was used to attach the samples to the measurement probes. The samples were first pressed with a pressure of 20 N for 30 s to ensure that the tape was properly attached. Thereafter, the probes were pulled apart at a speed of 80 mm / min. The recorded Z-directional strength is calculated as the average peak force of five parallel measurements; - Bending strength was determined in accordance with Standard EN 12089:2013 using a Lloyd LR10K universal tester. g) Thermal conductivity The thermal conductivity of the manufactured materials is measured with a Hot Disk Thermal Constants Analyzer based on Standard ISO 22007-2:2022. The measurement is performed in Bulk mode, from which Isotropic measurement and Low Density / High Insulating mode were selected using Sensor C5465. The sample pieces are placed on both sides of the sensor. Contact is secured with appropriate weight. Three measurements are made in parallel. 10s and 11mW are selected as measurement parameters by bracketing. During the measurement, the sensor is heated, and the sensor measures the change in resistance as a function of time. On this basis, the instrument can calculate, e.g., the penetration / depth of the heat wave into the sample, the rise in temperature, and the thermal conductivity of the sample. h) Structural characterization The structural characterization is done by µCT imaging (using a XµCT scanner, RX Solutions, best spatial resolution 4μm). Low voltage of 40 kV, current 300 µA and power 16 W was used for cellulose samples. Imaging parameters involved image number of 5 and frame rate of 4, resulting 30 min imaging time for each sample. The size of the imaged samples was 5 mm x 10 mm (thin structures) and 20 mm x 20 mm (thick structures). Voreen volume rendering engine was used for visualizing the XµCT images. The fiber orientation, porosity and average pore size may be calculated from the µCT images using computational image analysis. EXAMPLE 1: A fiber-based industrial (e.g., paperboard) material was produced in accordance with the method of the present disclosure. The dry pulp fibers were first separated by hammermilling using a KAMAS defibrator (Kvarn H01, M-NR 4.1224599, available from Kamas Industries AB), and pre-moisturized by spraying with water to a solids content of 30 to 50 wt.% inside a Forberg paddle mixer. The pre-moisturized fibers were fed into an extruder using agravimetric feeder and a conveyor belt (built at VTT facilityfor the current use). The feeding speed was set to reach the target solids content (20 to 35 wt.%) and total throughput (25 to 35 kg / h). The fibers were added into a foam flow. The foam was generated separately using a Hansa mixer (Top-mix) and fed into the extruder via a connection point before the fiber feeding section. The foam comprised the surface active agent and the binder (CMC) and had an air content of 95 vol.%. The foam flow (6.5 to 19 L / h) was adjusted based on the target throughput, i.e., 25 kg / h. The used screw was full length with internal bearings. The screw speed (200 to 600 rpm) was adjusted based on the fibrous foam and foam feeding speed such that the screw remained full with no overflow. A static slot die with a width of 210 mm and a die gap (height) of 6 mm was used for forming the fibrous foam into a continuous foam layer on a moving continuous conveyor unit (wire) with vacuum boxes. The conveyor unit speed was adjusted based on the material flow from the die. Three different sample types were collected: 1) Low density samples: samples were collected on a plastic carriers, placed in an oven and dried for 4h at 105°C until the structure was fully dry; 2) Medium density samples: samples were collected on a forming fabrics, dewatered ((five vacuum boxes in use: pressure in box 1=-0.2 bar, pressure in boxes 2-4= -0.4 bar, pressure in box 5= -0.7 bar) and then placed in an oven for drying; and 3) High density samples: samples were collected on a forming fabrics, dewatered and wet pressed using a hydraulic press (details 2 bar, 4 min and 200 bar, 2 min). The trials are listed in the table below. TrialFibers SolidsSL10 CMC Screw Hansa Fibrous # content (g / L) (kg / t) speed (foam) foam (Sc) (rpm) air air (wt.%) content content (vol.%) (vol.%) 1CTMP600:SW 20 10 85 300 70 65(70:30) 2CTMP600:SW 20 10 85 400 80 69(70:30) 3CTMP600:SW 20 10 85 600 90 75(70:30) Amount of CMC in kg per ton of fibers The properties of the samples were measured in accordance with the above methods. The results are shown in the table below. Basis weightThickness (µm) Density(g / m2) (kg / m3) No vacuum CTMP600:SW_H70% 440 5838 75CTMP600:SW_H80% 360 5792 62CTMP600:SW_H90% 255 4922 52Vacuum CTMP600:SW_H70% 446 3627 123CTMP600:SW_H80% 355 3124 114CTMP600:SW_H90% 226 2361 96 Pressed 2 barCTMP600:SW_H70% 425 1629 261CTMP600:SW_H80% 335 1252 268CTMP600:SW_H90% 207 824 252Pressed 200 barCTMP600:SW_H70% 490 1028 477CTMP600:SW_H80% 419 937 447CTMP600:SW_H90% 175 375 467

Claims

CLAIMS 1. A method of manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite,technical textiles, and / or abrasive paper material,the method including the steps of: -preparing a fibrous foam, wherein the preparingcomprises dispersing solids and one or more surface active agents in a liquid and / or a foam, with a solidscontent of 5% to 60% by weight, wherein at least 50% by weight of the solids are fibers, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content is 40% to 95% by weight, and supplying and dispersing gas in the liquid and / or the foam until agas content of 64% or more by volume is reached; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet, wherein the fibrous web or sheet has a liquid content of 20% to 85% by weight; and -drying the fibrous web or sheet to obtain a fiber-basedindustrial material.

2. The method of claim 1, wherein the dispersing of the gas in the liquid and / or the foam is performed using a feedback loop control, optionally including measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value.

3. The method of claim 1 or 2, wherein the preparing comprises supplying the gas and the liquid into a vessel such that a ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value, and mechanically mixing in the vessel for at least a predetermined amount of time or until a foamparameter, such as a foam height and / or a gas content reaches a predetermined minimum threshold.

4. The method of any one of the preceding claims, wherein the liquid comprises at least 80% by weight of water, and / or the gas used to prepare the fibrous foam comprises at least 95% air by volume.

5. The method of any one of the preceding claims, wherein the fibrous foam comprises a liquid with at least 80% by weight of water, and / or a gas with at least 95% air by volume.

6. A method of manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material,the method including the steps of: -preparing a fibrous foam, wherein the preparingcomprises dispersing solids and one or more surface active agents in a liquid and / or a foam, wherein at least 50% by weight of the solids are fibers, and supplying and dispersing gas in the liquid and / or the foam, thereby reaching a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less; -forming the fibrous foam into a foam layer;- draining the fibrous foam in the foam layer to form afibrous web or sheet; and -drying the fibrous web or sheet to obtain a fiber-basedindustrial material.

7. The method of any one or the preceding claims, wherein the fibrous foam in the foam layer is drained to form the fibrous web or sheet with a solids content of 15% to 80% by weight, wherein, optionally, the foam layer prior to draining has a solids content in a range of from 5% to 60%.

8. The method of any one of the preceding claims, wherein the dispersing of the gas in the liquid is performed using a feedback loop control, optionally including measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value.

9. The method of any one of the preceding claims, wherein the preparing comprises supplying the gas and the liquid into a vessel such that a ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value, and mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and / or a gas content reaches a predetermined minimum threshold.

10. The method of any one of the preceding claims, wherein the liquid comprises at least 80% by weight of water, and / or wherein the gas comprises at least 95% air by volume.

11. The method of any one of the preceding claims, wherein a gas content is 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume.

12. The method of any one of the preceding claims, wherein the fibrous foam comprises a liquid with at least 80% by weight of water, and / or a gas with at least 95% air by volume.

13. The method of any one of the preceding claims, wherein the preparing comprises processing dry fibers or solids, moisturized fibers or solids, a liquid slurry, or a foam, and fibers into the fibrous foam.

14. The method of claim 13, wherein the processing is at least partially performed by a transporting means that transportsthe fibrous foam to a forming means that forms the fibrous foam into the foam layer.

15. The method of claim 14, wherein the processing is performed by the transporting means.

16. The method of claims 7 and 14 or 7 and 15, wherein the processing is performed by a processing means and the draining of the fibrous foam is performed by a draining means, wherein, optionally, one or several of the following components are part of one integral structural unit: the preparation means, the processing means, the transporting means, the forming means, and the draining means, wherein, optionally, the processing means comprises the transporting means.

17. The method of any one of claims 14 to 16, wherein the processing comprises increasing a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar, and, optionally, 10 bars or less.

18. The method of any claim 17, wherein the increasing of the pressure comprises successively applying a plurality of different pressure levels in the downstream direction, wherein the pressure level is optionally decreased twice or more and / or the pressure level is optionally increased twice or more.

19. The method of any one of claims 14 to 18, wherein the processing and / or transporting comprises at least one of: shear, elongational, and / or distributive mixing,defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives.

20. The method of any one of the preceding claims, wherein the preparing comprises supplying a rheology modifier.

21. The method of any one of the preceding claims, wherein the draining of the fibrous foam comprises, optionally consists of, suction and / or mechanical draining such as pressing.

22. The method of any one of the preceding claims, wherein the fiber-based industrial material has a liquid content of 0.5% to 15% by weight, optionally, 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight, wherein, optionally, the fiber-based industrial product has a water content of 0.5% to 10% by weight, optionally, 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight.

23. The method of any one of the preceding claims, wherein the prepared fibrous foam has a solids content of more than 10% by weight, optionally a fiber content of more than 10% by weight.

24. The method of any one of the preceding claims, wherein the forming of the fibrous foam into a foam layer comprises bringing the fibrous foam into a planar form.

25. The method of any one of the preceding claims, comprising bringing a liquid slurry, a foam, optionally the fibrous foam, into contact with at least one rotatable means and rotating the at least one rotatable means to transport and / or to process the foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute.

26. The method of claim 25, wherein the rotating of the at least one rotatable means promotes defiberizing and / or deflocculating at least a part of the fibers, optionally, all of the fibers.

27. The method of claim 25 or 26, wherein the liquid slurry, the foam, optionally the fibrous foam, is transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin- screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means.

28. The method of any one of claims 25 to 27, wherein the rotatable means is housed by a housing and a minimum distance between the rotatable means and the housing during rotation is in the range of 0.2 to 20% of a diameter of the at least one screw, and, optionally, in the range of from 0.3 mm to 20 mm.

29. The method of any one of claims 25 to 28, wherein the rotating of the at least one rotatable means promotes at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating,refining, dispersing, disintegrating, changing fiber shapes, and heating.

30. The method of any one of claims 25 to 29, wherein the liquid slurry, and / or the foam, and / or the fibrous foam is generated in and / or transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple- screw machine, a conical screw mixer, comprising the at least one rotatable means.

31. The method of any one of claims 25 to 30, wherein the rotatable means is housed by a housing and a minimum distance between the rotatable means and the housing during rotation is in the range of from 0.3 mm to 20 mm.

32. The method of claim 30, comprising supplying, to the liquid slurry, and / or the foam, and / or the fibrous foam, when transporting it through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and / or a liquid slurry; and - a solid, such as fibers, powder, and / or granulate.

33. The method of any one of claims 25 to 32, wherein the rotating of the at least one rotatable means comprises rotating a twin-screw, a single-screw, or a multiple-screw, and the transporting the fibrous foam by rotating the at least one rotatable means comprises one or several of the following: accelerating the fibrous foam; decelerating the fibrous foam; applying a shear and / or elongation force to the fibrous foam.

34. The method of any one of claims 25 to 33, wherein the rotating of the at least one screw is performed in a screw assembly, such as an extruder or a screw mixer, the screw assembly comprises a housing and the at least one screw, wherein a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 0.2% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm.

35. The method of any one of claims 25 to 34, wherein the at least one rotatable means comprises at least a first screw and a second screw, and a distance of closest approach between the first screw and the second screw during rotations is in the range of from 0.3 mm to 20 mm.

36. The method of any one of claims 25 to 35, wherein the at least one rotatable means comprises a plurality of screwsand at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm.

37. The method of claim 7 or any claim dependent on claim 7, wherein the fibrous foam is displaced, prior to the forming, by a displacement pump, optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, or a flexible impeller pump.

38. The method of claim 7 or any claim dependent on claim 7, wherein the draining comprises applying a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation.

39. The method of claim 7 or any claim dependent on claim 7, wherein the draining is performed by successively applying at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure.

40. The method of any one of the preceding claims, wherein the forming of the fibrous foam into the foam layer is at least in part performed in a die and / or a headbox and / or a cylindrical mold former and / or a suction breast roller, and / or wherein the processing and / or the forming of the foam layer is performed in a controlled pressure chamber.

41. The method of claim 40, wherein the die is a slot die with an adjustable die gap, wherein the fibrous foam is processed into a continuous fibrous web or sheet on a moving continuous dewatering / conveyor unit.

42. The method of any one of the preceding claims, comprising, prior to the step of preparing the fibrous foam, a step of preparing a slurry comprising at least one component selected from the group consisting of: water, fibers, a surface active agent, a binder, and a slipping agent; wherein the preparing of the slurry is optionally at least partially performed in a high consistency mixing apparatus.

43. The method of any one of the preceding claims, wherein the drying is thermal, freeze, infrared, microwave, contact, impingement, or through air drying.

44. The method of any one of the preceding claims, wherein the preparing of the fibrous foam comprises supplying at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, zwitterionic surface active agents, amphoteric surface active agents, and nonionic surface active agents.

45. The method of any one of the preceding claims, wherein the preparing of the fibrous foam comprises supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent, the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, and sucrose esters.

46. The method of claim 45, wherein the at least one nonionic surface active agent is selected from the group consisting of alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols, the at least one nonionic surface active agent being optionally an alkylpolyglucoside of the general formula (1):R1-O-(R2)n-H (1)wherein, R1is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R2is a hexose or pentose unit, n is 1 to 5.

47. The method of any one of the preceding claims, wherein the preparing of the fibrous foam comprises pre-moisturizing the fibers and mixing, optionally with a paddle mixer, until a solids content in the range of 30% to 50% by weight is reached, to form pre-moistened fibers, the solids content being based on the total weight of the pre-moistened fibers.

48. The method of claim 47, as dependent on claim 13, wherein the pre-moistened fibers are conveyed and fed to the processing means, wherein the feeding is optionally performed using a volumetric and / or gravimetric feeder.

49. The method of any one of the preceding claims, wherein the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means is promoted by the same mechanical movement.

50. A fiber-based industrial material that is manufacturable by the method according to any one of the preceding claims.

51. The fiber-based industrial material of claim 50, wherein the fiber-based material has a basis weight of 50 to 800 g / m and a density of 200 to 1200 kg / m and / or wherein avariation σ of the basis weight between samples with surfaceareas of 1mm x 1mm is less than 10%, less than 7%, or less than 4% of the mean basis weight of the fiber-based industrial material.

52. A fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non- hygienic composite, technical textiles, and / or abrasivepaper material,comprising at least 50 wt.-% of fibers based on the total weight of the fiber-based material, wherein the fiber-based material has a basis weight of 50 to 800 g / m and a density of 200 to 1200 kg / m, and whereina variation σ of the basis weight between samples withsurface areas of 1mm x 1mm is less than 10%, less than 7%, or less than 4% of the mean basis weight of the fiber-based material.

53. The fiber-based industrial material of any one of claims 50 to 52, comprising a surface active agent.

54. The fiber-based industrial material of claim 52 or 53, wherein the fiber-based material has an upper side and a lower side, and a density in a central region of the fiber- based material located between the upper and lower sides in a thickness direction is lower than a density in a region of the fiber-based material located at the lower and / or upper side(s).

55. The fiber-based industrial material of any one of claims 52 to 54, which comprises one or more of the following (a) to (e): (a) at least 0.5 wt.-% of one or more binders, (b) at least 0.05 wt.-% of one or more rheology modifiers, (c) at least 0.01 wt.-% of one or more surface active agents, (d) at least 0.2 wt.-% of one or more slipping agents, and (e) at least 0.5 wt.-% of one or more fillers, each based on the total weight of the fiber-based material.

56. An apparatus for manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite,technical textiles, and / or abrasive paper material,comprising:- a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means comprises a supply means that supplies solids, one or more surface active agents, a liquid, and gas, wherein a solids content is 5% to 60% by weight, and wherein at least 50% by weight of the solids are fibers, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume.

57. The apparatus of claim 56, wherein the supply means supplies liquid and / or a foam, in which the surface active agents, the fibers, and the gas are dispersed, comprising at least 85% by weight of water, and / or gas being dispersed in the liquid and / or the foam comprising at least 95% air by volume.

58. The apparatus of claim 56 or 57, wherein the fibrous foam preparation means prepares a gas-liquid dispersion that comprises a liquid content of at least 85% by weight of water, and / or a gas content of at least 95% air by volume.

59. An apparatus for manufacturing a fiber-based industrial material, such as a fiber-based packaging, paperboard, filtration, thermoformable non-hygienic composite, technical textiles, and / or abrasive paper material,comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer;- a draining means draining the fibrous foam in the foam layer to form a fibrous web or sheet optionally having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web or sheet to obtain a fiber-based industrial material, wherein the fibrous foam preparation means prepares the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less.

60. The apparatus of claim 59, wherein the fibrous foam preparation means prepares the fibrous foam with a solids content, wherein a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content is the fiber content.

61. The apparatus of claim 59 or 60, wherein a solids content is 5% to 60% by weight, at least 50% by weight of the solids are fibers, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, or at least 85%, or at least 90%, by volume.

62. The apparatus of any one of claims 56 to 61, wherein the fibrous foam preparation means comprises a processing means that processes a liquid slurry or a foam, and solids into the fibrous foam.

63. The apparatus of claim 62, wherein the processing means comprises a transporting means that transports the liquid slurry, and / or the foam, and / or the fibrous foam to the foam layer formation means, wherein, optionally, thetransporting means performs at least a part of the processing, wherein, optionally, the transporting means performs the processing.

64. The apparatus of claim 63, wherein the apparatus supplies the fibrous foam prepared by the fibrous foam preparation means to the transporting means.

65. The apparatus of claim 63, wherein the transporting means performs at least a part of the processing, wherein, optionally, the transporting means performs the processing.

66. The apparatus of any one of claims 56 to 65, wherein the fibrous foam preparation means transports the fibrous foam to the fibrous foam formation means.

67. The apparatus of any one of claims 56 to 66, wherein the fibrous foam preparation means promotes the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means by the same mechanical movement, and / or wherein the fibrous foam preparation means transports the fibrous foam to the forming means.

68. The apparatus of any one of claims 56 to 67, wherein one or several of the following components are part of one integral structural unit: the processing means, the fibrous foam preparation means, the transporting means, the forming means, and the draining means.

69. The apparatus of claim 63 or a claim dependent on claim 63, wherein the transporting means comprises a pressurization section that increases a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar and, optionally, 10 bars or less.

70. The apparatus of claim 69, wherein the pressurization section successively applies a plurality of different pressure levels in the downstream direction, the pressure being increased at least twice and / or decreased at least twice.

71. The apparatus of any one of claims 56 to 70, wherein the processing means performs at least one of the following: shear, elongational, and / or distributive mixing,defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives.

72. The apparatus of any one of claims 56 to 71, the apparatus further comprising one or several solids supply means supplying solids to the fibrous foam preparation means, and one or several liquid supply means supplying liquid to the fibrous foam preparation means, to form the fibrous foam with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam.

73. The apparatus of any one of claims 56 to 72, wherein the fibrous foam preparation means comprises a rheology modifier supply means that supplies a rheology modifier.

74. The apparatus of any one of claims 56 to 73, wherein the draining means is a mechanical draining means.

75. The apparatus of any one of claims 56 to 74, wherein the fibrous foam preparation means prepares the fibrous foam to have a solids content of more than 10% by weight, optionally a fiber content of more than 10% by weight.

76. The apparatus of any one of claims 56 to 75, wherein the fibrous foam formation means brings the fibrous foam into a planar form.

77. The apparatus of any one of claims 56 to 78, comprising at least one rotatable means, the apparatus bringing the fibrous foam into contact with the at least one rotatable means and rotating the at least one rotatable means to transport the fibrous foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute.

78. The apparatus of claim 77, wherein the rotating of the at least one rotatable means promotes at least one of the following: shear, elongational, and / or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and heating, transporting, exerting pressure on, and building up pressure on the fibrous foam.

79. The apparatus of claim 77 or 78, comprising at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple- screw machine, a conical screw mixer, comprising the at least one rotatable means.

80. The apparatus of any one of claims 77 to 79, comprising a housing that houses the rotatable means, wherein a minimum distance between the rotatable means and an opposing inner surface of the housing is in the range of 0.2 to 20% of a diameter of the at least one rotatable means, and, optionally, in the range of 0.3 to 20 mm.

81. The apparatus of claim 79 or 80, comprising a supply means supplying, while the fibrous foam is prepared and / or processed and / or transported through the extruder, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air;- a foam and / or a liquid slurry; and - a solid, such as fibers, powder and / or granulate.

82. The apparatus of any one of claims 77 to 81, wherein the at least one rotatable means is a twin-screw, a single-screw, or a multiple-screw, and the at least one rotatable means optionally comprises one or several of the following sections: an acceleration section that accelerates the fibrous foam being transported through the processing device; a deceleration section that decelerates the fibrous foam being transported through the processing device; a shear application section that applies a shear and / or elongation force to the fibrous foam.

83. The apparatus of any one of claims 77 to 82, comprising a screw assembly that comprises a housing and the at least one screw, wherein a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 0.2% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm 84. The apparatus of any one of claims 77 to 83, wherein the at least one rotatable means comprises at least a first screw and a second screw, and a distance of closest approach between the first screw and the second screw during rotations is in the range of from 0.3 mm to 20 mm.

85. The apparatus of claims 77 to 84, wherein the at least one rotatable means comprises a plurality of screws and at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm.

86. The apparatus of any one of claims 56 to 85, comprising a displacement pump, optionally, a rotary lobe pump, aprogressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, that, prior to the forming, displaces the fibrous foam.

87. The apparatus of any one of claims 56 to 86, wherein the draining means applies a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation.

88. The apparatus of any one of claims 56 to 87, wherein the draining means successively applies at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure.

89. The apparatus of any one of claims 56 to 88, wherein the foam layer formation means comprises a die and / or a headbox and / or a cylindrical mold former and / or a suction breast roll former.

90. The apparatus of claim 62 or a claim dependent on claim 62, wherein the processing means and / or the foam layer formation means are provided in a controlled pressure chamber.

91. The apparatus of any one of claims 56 to 90, comprising a slurry preparation device that prepares an intermediate mixture / slurry foam / slurry solution comprising at least one component selected from the group consisting of: water, fibers, one or more surface active agents, one or more binders, and one or more slipping agents; the slurry preparation device optionally comprising in a high consistency mixing apparatus.

92. The apparatus of any one of claims 56 to 91, wherein the drying means is a thermal, freeze, infrared, microwave, contact, impingement, or through air drying means.

93. The apparatus of any one of claims 56 to 92, comprising a surface active agent supply means that supplies at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents.

94. The apparatus of any one of claims 56 to 93, comprising a temperature control means that controls a temperature inside at least one section of the apparatus.

95. The apparatus of any one of claims 56 to 94, comprising a control device that controls the apparatus to perform the method of any one of claims 1 to 49.

96. Use of the apparatus of any one of claim 56 to 95 for manufacturing a fiber-based industrial product.

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