Solid cellulose foam body formed by assembly of at least two solid cellulose foam sections

Abstract

The present invention relates to a solid cellulose foam article comprising a first solid cellulose foam portion attached to a second solid cellulose foam portion, and optionally at least one additional solid cellulose foam portion attached to the first and / or second solid cellulose foam portions. The present invention also relates to a method of making the solid cellulose foam article.

Description

[Technical Field]

[0001] The present invention relates to a solid cellulose foam body formed by the assembly of at least two solid cellulose foam sections, and to a method for making such a solid cellulose foam body. The solid cellulose foam body of the present invention can be used as a cushioning material for packaging. [Background technology]

[0002] Various porous materials, such as foams, are commonly used as insulation in buildings and vehicles, and as packaging materials used to protect various items during storage and transport.

[0003] Depending on the item being protected, various types of protective packaging materials can be used. Many items use lightweight cushioning materials to reduce shock and vibration. Common examples of such cushioning materials include polyurethane, polyethylene, and petroleum-based polymer foams such as Styrofoam. The foams used need to be lightweight, stable, and easy to manufacture.

[0004] There is growing interest in replacing petroleum-based polymers with polymers derived from renewable resources, i.e., bio-based polymers. Cellulose is the most abundant renewable natural polymer on Earth and is therefore of particular interest. Depending on the foam's composition, cellulosic foams may allow for the material to be recycled in conventional recycling streams.

[0005] There are several examples of cellulose foams, each prepared using a different method. Drying the wet foam composition is often a critical step. Because wet foams typically have low stability, molds are commonly used to prevent the foam from collapsing during drying. WO 20200011587 describes a porous material prepared by aerating a paste containing cellulose fibers and gluten, placing the aerated paste in a mold, and drying the paste. The dried porous material has the shape of the mold. WO 2015036659 describes a molded fiber product prepared by foaming an aqueous suspension combining natural and synthetic fibers and surfactants, feeding the fibrous foam into a mold, first mechanically extracting a portion of the water, and then drying the foam by evaporating the water to obtain a dry fiber product.

[0006] When a cellulose foam object is dried without restraint, it will shrink in all directions due to the collapse of the foam as tension forces pull the cellulose fibers together. Drying shrinkage is an inherent property of cellulose, and when water is removed from the system, the swollen cellulose fibers will collapse onto each other. Even with more complex drying systems, such as those combining air impingement dryers and infrared dryers, shrinkage in the thickness direction of more than 10% is expected. This is because as the water level drops during drying, the internal capillary pressure of the material increases, causing meniscus formation between particles and resulting interparticle attractive forces. Increasing the dry content of the foam, which has low hydrophilicity and / or hydrophobicity, reduces the attractive forces generated by the capillary pressure between particles. However, the strength of the network formed during drying is reduced by a decrease in the interfiber bond strength and the average number of interfiber bonds.

[0007] To avoid or mitigate shrinkage during drying, cellulose foam objects must be dried under tension, such as in a frame or mold. Using such restraints will significantly reduce shrinkage across the width and length of the foam. However, when drying objects with large surface areas, the tension provided by the mold is limited to the area closest to the mold. Typically, foam thickness decreases due to shrinkage in the center of the object and gradually increases toward the edges. Therefore, shrinkage during drying is problematic, particularly when drying foam objects with large surface areas, because shrinkage can be uneven and the thickness of the dried foam can vary along the width and length of the dried foam.

[0008] Because both wet and dry cellulose foams are insulating, the drying time for cellulose foams is typically long, and shortening the drying time is desirable for a cost-effective process.

[0009] Therefore, there is still a need for alternative methods for preparing cellulose foams. In addition, the foams prepared should have high impact resistance so that they can protect heavier parts when used as packaging materials. Summary of the Invention

[0010] It is an object of the present invention to provide a solid cellulose foam that is recyclable and produced from renewable resources, and that eliminates or mitigates at least some of the disadvantages of prior art materials.

[0011] It is a further object of the present invention to provide a solid cellulose foam that is dimensionally stable.

[0012] It is a further object of the present invention to provide an improved method for obtaining solid cellulose foams having uniform thickness and minimal non-uniform shrinkage during drying, even when producing large foam articles.

[0013] A further object of the present invention is to provide a cost-effective method for obtaining solid cellulose foams, in which the drying time of the foam is reduced.

[0014] The above objectives, as well as other objectives which will be realized by those skilled in the art in light of this disclosure, are achieved by various aspects of the present disclosure.

[0015] The invention is defined by the independent claims. Further embodiments of the invention are defined by the dependent claims.

[0016] According to a first aspect, the present invention relates to a solid cellulose foam article comprising: a first solid cellulose foam portion comprising a first connecting surface and optionally a second connecting surface; and a second solid cellulose foam portion comprising a first connecting surface and optionally a second connecting surface; wherein the first connecting surface of the first solid cellulose foam portion and the first connecting surface of the second solid cellulose foam portion are attached to each other to form a solid cellulose foam article; and the solid cellulose foam article optionally comprises at least one additional solid cellulose foam portion comprising a first connecting surface and optionally a second connecting surface, and wherein the first connecting surface of the at least one additional solid cellulose foam portion is attached to the second connecting surface of the first solid cellulose foam portion and / or the second solid cellulose foam portion.

[0017] Surprisingly, it has been found that assembling at least two solid cellulose foam sections into a solid cellulose foam object can result in a dimensionally stable foam product without thickness variations due to uneven shrinkage. Because the solid cellulose foam object is prepared by assembling smaller solid cellulose foam sections, drying of a large foam object is avoided. Each solid cellulose foam section used to assemble the solid cellulose foam object is prepared with a shape that avoids or minimizes uneven shrinkage through the thickness during drying. Such shapes may have similar height and width dimensions. It has been found that such shapes will minimize uneven shrinkage during drying. The solid cellulose foam sections can also be prepared with complementary shapes that fit together to form a solid cellulose foam object without internal voids after assembly. Depending on the desired size of the solid cellulose object, two or more solid cellulose foam sections can be assembled. Thus, the present invention enables the production of very large cellulose foam structures. In addition, the bonding of the first connecting surfaces of the first and second solid cellulose foam sections provides an additional internal interface within the solid cellulose foam object. This will improve the mechanical properties, for example the compressive strength of the solid cellulose foam object, due to the increased number of rigid interfaces.

[0018] It was also surprisingly found that drying at least two smaller cellulose foam sections, rather than one larger cellulose foam structure, reduced the overall drying time. Because both wet and dry cellulose foams are insulating, larger foam objects typically require longer drying times. Alternatively, drying smaller foam sections individually would provide a higher surface area to thickness ratio and therefore reduce drying time. The ability to simultaneously dry multiple smaller sections further reduced the overall drying time. This is also beneficial from a cost perspective, as less energy is required for drying.

[0019] According to a second aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: - providing at least one wet cellulose foam; - shaping and drying the wet cellulose foam to obtain a first solid cellulose foam portion; a second solid cellulose foam portion; and optionally at least one additional solid cellulose foam portion, wherein the first solid cellulose foam portion comprises a first connecting surface and optionally a second connecting surface; the second solid cellulose foam portion comprises a first connecting surface and optionally a second connecting surface, and the optional at least one additional solid cellulose foam portion comprises a first connecting surface and optionally a second connecting surface; - attaching a first connecting surface of a first solid cellulose foam portion to a first connecting surface of a second cellulose foam portion to obtain a solid cellulose foam object; - optionally attaching a first connecting surface of at least one additional cellulose foam portion to a second connecting surface of the first solid cellulose foam portion and / or a second solid cellulose foam portion; The present invention relates to a method for producing a solid cellulose foam body, comprising:

[0020] By selecting an appropriate shape for the wet cellulose foam portion in the forming step, uneven shrinkage is prevented and the resulting solid cellulose foam portion can be used for assembly into a dimensionally stable solid cellulose foam object of uniform thickness.

[0021] The solid cellulose foam body according to the first aspect may be obtained by the method according to the second aspect.

[0022] According to a third aspect, the present invention relates to the use of a solid cellulose foam according to the first aspect as a packaging material, a building material, a thermal insulation material, an acoustic insulation material, or a hydroponic plant growing medium.

[0023] The solid cellulose foam according to the first aspect has high impact resistance and excellent cushioning properties, and can be used as a packaging material in a variety of protective packaging applications. It can also be used as a building material, or as a thermal or acoustic insulation material. The solid cellulose foam can also be used as a hydroponic plant growing medium. The solid cellulose foam body is made from renewable resources and can be redispersed in water, making it recyclable in the normal paper recycling stream.

[0024] The cellulose foam of the present invention preferably comprises cellulose fibers in the range of 71 to 95 wt. % calculated on the total weight of the solids content of the foam, a water-soluble thickener in the range of 4 to 24 wt. % calculated on the total weight of the solids content of the foam, and at least two surfactants.

[0025] Embodiments of the present invention are best understood by referring to the following description and the accompanying drawings, in which: The present invention will be explained in more detail with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0026] [Figure 1a] 1 is a schematic diagram of one embodiment of a solid cellulose foam object assembled from first and second solid cellulose foam portions, each portion being equal in size. [Figure 1b] FIG. 1 is a schematic diagram of one embodiment of a solid cellulose foam object assembled from first, second, and one additional solid cellulose foam portions, each portion being a different size. [Figure 1c] FIG. 1 is a schematic diagram of one embodiment of a solid cellulose foam object assembled from first, second, and two additional solid cellulose foam portions, each portion being equal in size. [Figure 1d] Schematic diagram of one embodiment of a solid cellulose foam object assembled from a total of eight solid cellulose foam pieces, each piece being equal in size. [Figure 2]1 is a schematic diagram of one embodiment of first, second, and two additional solid cellulose foam portions assembled into a solid cellulose foam object, the solid cellulose foam portions being equal in size. [Figure 3a] Schematic diagram of one embodiment of a first solid cellulose foam portion including four protruding portions in the shape of pillars; and a second solid cellulose foam portion including four recessed portions having shapes corresponding to the pillars of the first solid cellulose foam portion. [Figure 3b] Schematic diagram of a solid cellulose foam body formed by assembly of the parts shown in FIG. 3a. [Figure 4a] 1 is a schematic diagram of an embodiment of a first solid cellulose foam portion and a second solid cellulose foam portion, both foam portions having a first connecting surface that includes both protrusions and recesses, the protrusions and recesses extending along the entire length of the foam portions, and the connecting surface having a sinusoidal corrugation in cross section. [Figure 4b] 4a is a schematic side view of a solid cellulose foam object formed by assembly of the parts shown in FIG. [Figure 5a] 1 is a schematic diagram of one embodiment of a first solid cellulose foam portion comprising regularly spaced pillars; and a second solid cellulose foam portion having a shape complementary to the shape of the first solid cellulose foam portion. [Figure 5b] 5a is a schematic diagram of a solid cellulose foam body formed by assembly of the parts shown in FIG. [Figure 6] Graph of drying curves obtained during drying of wet cellulose foam deposited in one step, with the reference shapes being a foam sheet with a flat surface (◇), a rod shape (□), a foam sheet with a top surface having a sinusoidal wave shape (○), or a foam sheet with a bottom surface having a triangular wave shape (▲). DETAILED DESCRIPTION OF THE INVENTION

[0027] Embodiments of the present invention relate to the assembly of solid cellulose foam sections of various shapes into solid cellulose foam bodies.

[0028] As used herein, the term "foam" refers to a material produced by trapping air or gas bubbles within a solid or liquid. Typically, the volume of gas is much greater than the volume of the liquid or solid, with a thin membrane separating the gas pockets. For a foam to form, three requirements must be met. Mechanical work is required to increase the surface area. This can be done by agitation, dispersing a large amount of gas into the liquid, or injecting gas into the liquid. The second requirement is that a foaming agent (usually an amphiphile, surfactant, or surface-active component) must be present to reduce the surface tension. Finally, the foam must form faster than it can break down.

[0029] As used herein, the term "cellulose foam" refers to a foam containing cellulose and other components such as thickeners, surfactants, and additives. The main component of cellulose foam is cellulose, which accounts for at least 70% by weight of the dry weight of the cellulose foam. Cellulose is in the form of fibers, and therefore the foam can also be defined as a fibrous foam or a cellulose fiber foam. The cellulose foam can be in a wet or solid state.

[0030] As used herein, the terms "wet foam" or "wet cellulose foam" refer to a wet foam comprising cellulose and other components such as thickeners, surfactants, and additives. Air bubbles are present within the wet foam. The wet foam is self-supporting and behaves as a viscoelastic solid, meaning that it possesses both viscous and elastic properties. The wet foam behaves as a solid and is self-supporting unless sufficient force is applied to it, causing it to begin to flow and behave as a viscous material. Depending on the magnitude and time scale of the applied shear stress, the wet foam may exhibit primarily viscous or elastic behavior.

[0031] As used herein, the terms "solid cellulose foam" or "dried cellulose foam" refer to a dry porous cellulose material, i.e., a foam-forming material, formed from wet cellulose foam. During the drying process, the closed wet cellulose foam is converted into an open solid cellulose foam. The cellulose fiber network is prevented from collapsing during drying. As a result, the solid cellulose foam will have a shape that generally matches the shape of the wet cellulose foam. The dry content of the solid cellulose foam is at least 95% by weight, calculated based on the total weight of the solid cellulose foam. The shape and density of the solid cellulose foam are maintained even in an unconfined state. Solid cellulose foam has an open-cell structure, allowing air to enter the pores within the foam. Solid cellulose foam is sometimes referred to as a porous material or a low-density material.

[0032] We now turn to a detailed description of the cellulose foam preferably used in the cellulose foam portion of the present invention.

[0033] The cellulose foam used in the present invention preferably contains cellulose fibers in the range of 71 to 95% by weight, for example 75 to 95% by weight, based on the total dry weight of the cellulose foam.

[0034] Cellulose fibers suitable for use in the present invention can be derived from wood, such as softwood or hardwood, leaves, or fiber crops (including cotton, flax, and hemp). Cellulose fibers suitable for use in the present invention can also be derived from regenerated cellulose, such as rayon and lyocell. Cellulose fibers suitable for use in the present invention can contain lignin or hemicellulose or both, or the cellulose fibers can be free of lignin and hemicellulose. Preferably, the cellulose fibers are derived from wood, and more preferably, the cellulose fibers are pulp fibers obtained by a pulping process that releases fibers from the wood matrix. Pulp fibers can be separated by mechanical pulping to obtain mechanical pulps, such as thermomechanical pulp (TMP) or chemical thermomechanical pulp (CTMP), or by chemical pulping, such as kraft pulp or pulps obtained by sulfite, soda, or organosolv pulping processes. More preferably, the cellulose fibers are pulp fibers separated by a chemical pulping process. The different properties of each cellulose fiber will affect the properties of the final cellulose foam. Cellulose fibers are much longer than their width. Cellulose fibers can have an average width of 0.01 to 0.05 mm. Softwood fiber lengths can be 2.5 to 4.5 mm, while hardwood fiber lengths can be 0.7 to 1.6 mm, and eucalyptus fiber lengths are 0.7 to 1.5 mm. However, fiber lengths can vary significantly depending on the habitat and other factors. The cellulose fibers in the cellulose foams disclosed herein can have lengths of 0.1 to 65 mm, 0.1 to 10 mm, 0.5 to 65 mm, 0.5 to 10 mm, or 0.5 to 7 mm. Fiber length can provide different mechanical properties to the foam. Due to the fiber length, the fibers can intertwine with each other, resulting in fiber-to-fiber bonds and strength for the foam.The aspect ratio, i.e., the ratio of fiber length to fiber width of the cellulose fibers in the cellulose foam according to the present invention, may be at least 10, at least 25, at least 50, at least 75, or at least 100, which maintains and stabilizes the foam structure during the drying process, allowing the wet cellulose foam to dry while retaining its shape. The aspect ratio may be up to 6500, or preferably up to 2000.

[0035] Cellulose fibers can be modified to provide different properties to the final cellulose foam, for example, phosphorylated or periodate oxidized fibers can be used when making cellulose foams according to the present invention.

[0036] Preferably, the cellulose fibers are selected from wood pulps such as bleached softwood kraft pulp, hardwood pulp, chemical-thermomechanical pulp, and dissolving pulp, or a combination of one or more thereof. More preferably, the cellulose pulp fibers are derived from softwood pulp, chemical-thermomechanical pulp, or dissolving pulp. Most preferably, the cellulose pulp fibers are derived from softwood pulp, such as bleached softwood kraft pulp.

[0037] The cellulose foam used in the present invention preferably comprises cellulose fibers in the range of 71 to 95 wt. %, for example 75 to 95 wt. %, based on the total dry weight of the cellulose foam, a water-soluble thickener in the range of 4 to 24 wt. %, for example 5 to 20 wt. %, based on the total dry weight of the cellulose foam, and at least two surfactants.

[0038] The cellulose foams used in the first, second, and additional solid cellulose foam portions may have the same composition or different compositions.

[0039] The water-soluble thickener may have a molecular weight of 80,000 to 250,000 g / mol, or 83,000 to 197,000 g / mol. Exemplary water-soluble thickeners are selected from carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose (HEC), ethyl hydroxyethyl cellulose (EHEC), methyl hydroxypropyl cellulose (MHPC), starch, xanthan gum, guar gum, and xyloglucan, or mixtures thereof. The water-solubility of the thickener facilitates recycling of the cellulose foam.

[0040] Water-soluble thickeners can improve the interfiber bond strength in cellulose foams, mainly through hydrogen bonding. Therefore, the amount of water-soluble thickener will affect the mechanical performance of the cellulose foam, especially the bulkiness of the material. A higher content of water-soluble thickener provides a higher rigidity to the material. Therefore, water-soluble thickeners allow for customization of mechanical properties.

[0041] The cellulose foam may also contain a mixture of at least two surfactants. One of the at least two surfactants is preferably a fast-acting surfactant. A surfactant suitable for this purpose is an anionic surfactant, preferably a low-molecular-weight anionic surfactant. The anionic surfactant may have an apparent pKa of 3.2 to 3.8, preferably 3.4 to 3.6, or an apparent pKa of 3.5 in a solution having a pH of 7 to 9, preferably 8. The low-molecular-weight anionic surfactant may be selected from sodium dodecyl sulfate (SDS); potassium dodecyl sulfate, sodium laureth sulfate (SLES); sodium dodecylbenzenesulfonate; sodium cocoyl sarcosinate; and sodium lauroyl sarcosinate. The low-molecular-weight anionic surfactant is preferably selected from sodium dodecyl sulfate (SDS); sodium pn-dodecylbenzenesulfonate; sodium cocoyl sarcosinate; and sodium lauroyl sarcosinate. More preferably, the low-molecular-weight anionic surfactant is sodium cocoyl sarcosinate. The anionic surfactant may be biodegradable.

[0042] The other of the at least two surfactants is preferably a co-surfactant. The co-surfactant can be selected from the group consisting of surfactants having an apparent pKa of at least 8, or at least 9, in a surfactant solution having a pH of 7 to 9, preferably pH 8; and amphoteric betaines. The co-surfactant can have a maximum apparent pKa of 10. The co-surfactant preferably has a long carbon chain, more preferably a carbon chain having 14 carbon atoms (C14). The co-surfactant can be selected from high pKa fatty acids from plant-derived sources, such as tetradecanoic acid (myristic acid), sodium oleate, lauric acid, palmitic acid, and stearic acid; glucose-based co-surfactants with aliphatic carbon chains, such as alkyl glycosides, alkyl polyglucosides, alkyl thioglycosides, and alkyl maltosides; amphoteric betaines, such as cocamidopropyl betaine (CAPB) and sodium cocoiminodipropionate (CADP); polyethylene glycol sorbitan monolaurate, i.e., tween® (e.g., tween 20, tween 80, and tween 85); and polyoxyethylene lauryl ethers, such as polyethylene glycol dodecyl ether, pentaethylene glycol monododecyl ether, and octaethylene glycol monododecyl ether.

[0043] Therefore, the at least two surfactants used in the cellulose foam preferably comprise a mixture of an anionic surfactant and a co-surfactant. The molar ratio of the anionic surfactant to the co-surfactant may be 0.2:1 to 3:1, preferably 0.5:1 to 2:1. The total amount of the at least two surfactants contained in the cellulose foam may be 0.6 to 5 wt. % or 0.8 to 2.0 wt. % calculated based on the total weight of the cellulose foam.

[0044] The solid cellulose foam can be redispersed in water and therefore is recyclable in the normal paper recycling stream.

[0045] The wet cellulose foam is subjected to the following steps: - decomposing cellulose fibers in water to obtain a cellulose fiber slurry; - adding a water-soluble thickener to the slurry to obtain a mixture of thickener and cellulose fibers in water; - adding at least two surfactants to the mixture to obtain a fiber suspension; and - aerating a fiber suspension to obtain a wet foam, the wet foam comprising 10 to 38% by weight of cellulose fibers, 0.5 to 10% by weight of a water-soluble thickener, and 0.1 to 2% by weight of a surfactant, calculated relative to the total weight of the wet foam, and the wet cellulose foam has a viscosity of 120 to 500 kg / m 3 , or 120 to 400 kg / m 3 and a yield stress of at least 80 Pa. The compound can be prepared using a method comprising:

[0046] In some embodiments, the yield stress of the wet cellulose foam may be at least 80 Pa, or at least 100 Pa, or at least 150 Pa, or from 80 to 500 Pa, or from 100 to 500 Pa, or from 150 to 500 Pa.

[0047] The addition of water-soluble thickeners increases the viscosity of the slurry, allowing sufficient air to be entrapped during aeration to produce a tightly packed foam. Because the cellulose fibers are mixed at high concentrations, a drainage step is not necessary, allowing the use of high concentrations of water-soluble bio-based thickeners.

[0048] The addition of a fast-acting surfactant will contribute to the formation of a dense, high-viscosity cellulose foam, as it will settle quickly between the air-water phase during aeration. This allows for a self-supporting wet cellulose foam. The addition of a co-surfactant together with the fast-acting surfactant will further enhance the properties of the cellulose foam, as it will accelerate the action of the fast-acting surfactant. A co-surfactant with an appropriate pKa and long carbon chain will further contribute to the formation of a stable fiber suspension and a stable wet cellulose foam.

[0049] Upon aeration, a composition comprising cellulose fibers, a thickener, and at least two surfactants will form a highly stable wet fiber foam. Aeration can be achieved by mechanical agitation, incorporating a significant amount of air into the material. Foam formation may be facilitated by the surfactant. By tailoring the stability of the wet foam using a combination of a thickener and a surfactant, a free-standing cellulose foam can be produced without the use of crosslinkers or fibrillated cellulose. The foam's good stability prevents aging, i.e., changes in cell size, and drainage. The resulting wet foam is free-standing and does not require a mold or forming cloth to maintain its shape upon drying. The wet foam can be molded into a free-standing foam that is stable enough to dry without collapsing, even in the absence of a supporting mold. As a result, cellulose foam parts of the present invention can be molded and dried without the use of a mold. Depending on the shape of the wet cellulose foam, the amount of shrinkage during drying can be minimized, as further outlined in connection with various embodiments of the present invention. If a specific shape of dried foam is desired, it may be beneficial to dry the wet foam using a mold to improve precision.

[0050] In some embodiments, the yield stress of the wet cellulose foam used in the present invention may be at least 80 Pa, or at least 100 Pa, or at least 150 Pa, or from 80 to 500 Pa, or from 100 to 500 Pa, or from 150 to 500 Pa.

[0051] In some embodiments, the density of the wet cellulose foam used in the present invention is between 70 and 600 kg / m 3 , or 100 to 500 kg / m 3 , or 100 to 400 kg / m 3 , or 125 to 375 kg / m 3 , or 140 to 375 kg / m 3 It is possible.

[0052] In some embodiments, the wet cellulose foam used in the present invention comprises at least 10 wt. % cellulose, calculated based on the total weight of the wet cellulose foam. In some embodiments, the wet cellulose foam may comprise 10-40 wt. %, 11-40 wt. %, 10-30 wt. %, 11-30 wt. %, 10-20 wt. %, or 11-20 wt. % cellulose fibers, calculated based on the total weight of the wet cellulose foam.

[0053] The cell size in the wet foam is typically less than 100 μm. This results in a homogeneous wet foam with good stability that does not agglomerate during processing. The average cell size is generally maintained during processing and the subsequent drying step, and the cellulose fibers remain well dispersed. The solid cellulose foam obtained by drying the wet foam has a homogeneous structure, is strong, has good mechanical properties, a smooth surface, and is free of defects. A smooth surface is beneficial when attaching a substrate to the foam, as it can facilitate adhesion.

[0054] In contrast, less stable wet cellulose foams have larger average cell sizes (i.e., typically greater than 100 μm), which result in faster cell coalescence during processing and drying, resulting in the formation of larger cells. Additionally, cellulose fibers will form clusters during processing and drying, resulting in the collapse of the wet foam during drying. The resulting solid cellulose foam will not have a homogeneous structure and will contain defects, such as voids, resulting from the coalescence of cells in the wet foam. These defects will cause the solid cellulose foam to be brittle and have a rough surface.

[0055] Due to the high solids content, the wet foam does not need to be dehydrated before drying. The foam can be dried by evaporation at room temperature or at elevated temperatures, e.g., temperatures between 40°C and 140°C. After drying, the solid cellulose foam has a dry weight of 10 to 80 kg / m 3 , or 10 to 60 kg / m 3 or 20 to 50 kg / m 3 The solid cellulose foam may have a density of from 95 to 100% by weight, preferably from 98 to 100% by weight, calculated on the total weight of the solid cellulose foam, after drying.

[0056] In a preferred embodiment, the cellulose foam comprises 71 to 95 wt. % of cellulose fibers, e.g., 75 to 95 wt. % of cellulose fibers, based on the total dry weight of the cellulose foam; 4 to 24 wt. % of a water-soluble thickener, based on the total dry weight of the cellulose foam, e.g., 5 to 20 wt. % of a water-soluble thickener, based on the total dry weight of the cellulose foam; and at least two surfactants. A wet cellulose foam having such a composition has a homogeneous structure and, as discussed above, good stability. Such a wet cellulose foam can also be dried without prior dehydration.

[0057] The solid cellulose foams of the present invention are essentially rigid. As used herein, the term "essentially rigid" refers to a foam material that is hard, inelastic, and cannot bend or flexed without permanently damaging the material. Compression would damage the structure of the cellulose foam and permanently change the shape of the cellulose foam.

[0058] During drying, a dense layer forms on the outer surface of the wet cellulose foam and remains on the outer surface of the dried cellulose foam. The dense layer contains cellulose fibers that are more densely packed and partially oriented differently compared to the bulk. The dense layer has improved mechanical stability and strength compared to the core of the cellulose foam. The core of the cellulose foam contains a homogeneous open-cell fiber network. The core is highly porous, while the dense layer has a denser structure than the core, but is still porous. The dense layer provides the cellulose foam with improved stability and mechanical strength. The thin thickness of the dense layer means that it does not substantially affect the overall density of the cellulose foam.

[0059] The cellulose foams described above are preferred foams for use in the solid cellulose foam portion of the present invention. Alternatively, other cellulose foams can be used, such as those disclosed in WO2016068771, WO2016068787, and WO2020011587.

[0060] The first aspect of the present invention, i.e., a solid cellulose foam article formed by assembly of at least a first solid cellulose foam portion and a second solid cellulose foam portion, will now be described in more detail with reference to the drawings.

[0061] The first embodiment includes a first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 including a first connecting surface 511, 611, 711, 811 and optionally a second connecting surface 512; and a second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 including a first connecting surface 521, 621, 721, 821 and optionally a second connecting surface 522. 0; wherein the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 and the first connecting surface 521, 621 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 are , 721, 821 are attached to one another to form the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800; and the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 optionally includes at least one additional solid cellulose foam portion 230, 330, 430, 530, 531, 532, which optionally includes a first connecting surface 531 and optionally a second connecting surface 532. 0, and the first connecting surface 531 of at least one additional solid cellulose foam portion 230, 330, 430, 530 is attached to the second connecting surface 512, 612, 712, 812, 522, 622, 722, 822 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 and / or the second solid cellulose foam portion 220, 320, 420, 520.

[0062] As used herein, the term "solid cellulose foam body" refers to a foamed product of any shape, such as a block, cube, plate, cylinder, or any irregular shape. Preferably, the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 is rectangular prism-shaped. The solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 is assembled from at least two separate solid cellulose foam pieces that remain distinguishable from one another after assembly. After assembly, the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 resembles an object formed from a single piece of material, and there are no internal voids within the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800. The individual solid cellulose foam sections fit together so that no gaps or voids are formed during assembly. The solid cellulose foam sections are attached to one another so that they are not easily removable, i.e., permanently attached. The solid cellulose foam object 100, 200, 300, 400, 500, 600, 700, 800 is dimensionally stable. As used herein, the term "dimensionally stable" refers to an object that has no or minimal undesirable variations in dimensions. For example, the thickness can be uniform along the width and / or length of the object 100, 200, 300, 400, 500, 600, 700, 800.

[0063] The solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 is preferably essentially rigid. The solid cellulose foam portions used to assemble the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 are also preferably essentially rigid.

[0064] Solid cellulose foam materials 100, 200, 300, 400, 500, 600, 700, 800 are 10-80 kg / m 3 , or 10 to 60 kg / m 3 , or 20 to 50 kg / m 3The solid cellulose foam bodies 100, 200, 300, 400, 500, 600, 700, 800 may have a solids content in the range of 95-100 wt.%, preferably 98-100 wt.%, calculated on the total weight of the solid cellulose foam. The density of each solid cellulose foam portion used to assemble the solid cellulose foam bodies 100, 200, 300, 400, 500, 600, 700, 800 may be in the range of 10-80 kg / m 3 , or 10 to 60 kg / m 3 , or 20 to 50 kg / m 3 The solids content of each solid cellulose foam portion used to assemble the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 can range from 95 to 100% by weight, preferably 98 to 100% by weight, calculated on the total weight of the solid cellulose foam.

[0065] In all embodiments of the present invention, the cellulose foam composition of the individual solid cellulose foam portions may be the same or different. Other properties of the at least two individual pieces, such as density, size, and shape, may also be the same or different. By selecting solid cellulose foam portions with specific shapes and properties, versatile foam materials can be provided with tailored properties, such as stiffness and impact resistance, depending on the intended application.

[0066] As used herein, the term "connecting surface" refers to any surface of a solid cellulose foam portion that can be used to partially or completely attach the solid cellulose foam portion to another adjacent solid cellulose foam portion. The connecting surface of a solid cellulose foam portion may or may not be attached to the connecting surface of another solid cellulose foam portion. The connecting surface may be flat or may include protruding portions and / or recessed portions.

[0067] The connecting surface may include a dense layer, which may increase the strength of the connecting surface and facilitate adhesion to another connecting surface.

[0068] In one embodiment of the present invention, as shown in Figure 1a, a solid cellulose foam article 100 is assembled by attaching a first solid cellulose foam portion 110 and a second solid cellulose foam portion 120. In other embodiments, as shown in Figures 1b, 1c, 1d and 2, at least one additional solid cellulose foam portion 230, 330, 530 is assembled in addition to the first cellulose foam portion 210, 310, 510 and second solid cellulose foam portion 220, 320, 520.

[0069] In some embodiments, as shown in FIG. 1 a, when a solid cellulose foam object 100 is assembled from two solid cellulose foam sections 110, 120, only one connecting surface of each solid cellulose foam section 110, 120 will be connected to the connecting surface of another solid cellulose foam section 110, 120.

[0070] 2 illustrates one embodiment of the present invention in which four equal sized solid cellulose foam sections 510, 520, 530 are assembled into a solid cellulose foam body 500. The solid cellulose foam body 500 has a rectangular parallelepiped shape and has a length l O , height h O and width w O The solid cellulose foam object 500 includes a first solid cellulose foam portion 510 including a first connecting surface 511 and a second connecting surface 512; a second cellulose foam portion 520 including a first connecting surface 521 and a second connecting surface 522; and two additional solid cellulose foam portions 530, each including a first connecting surface 531 and a second connecting surface 532. During assembly of the solid cellulose foam object, the first connecting surface 511 of the first solid cellulose foam portion 510 is attached to the first connecting surface 521 of the second solid cellulose foam portion 520. The first connecting surfaces 531 of the two additional solid cellulose foam portions 530 are attached to the second connecting surfaces 512, 522 of the first solid cellulose foam portion 510 and the second solid cellulose foam portion 520, respectively.

[0071] The connecting surfaces 511, 512, 521, 522, 531, 532 of the embodiment of Figures 1 and 2 are all flat. Flat connecting surfaces facilitate the assembly of solid foam sections of the same shape.

[0072] In the embodiment shown in Figure 2, the first connecting surface 511, 521, 531 and the second connecting surface 512, 522, 532 of the solid cellulose foam portion are on opposite sides of the solid cellulose foam portion. In other embodiments, as shown in Figure 1c, the connecting surfaces are on adjacent sides of the solid cellulose foam portion 320. In some embodiments, as also shown in Figure 1c, the solid cellulose foam portion 320 can include additional connecting surfaces. The solid cellulose foam portion 320 of Figure 1c includes three connecting surfaces.

[0073] The four solid cellulose foam sections 510, 520, 530 in the embodiment shown in Figure 2 are all rectangular parallelepiped in shape. The first solid cellulose foam section 510 has a length l1, a width w1, and a height h1, the second solid cellulose foam section 520 has a length l2, a width w2, and a height h2, and the two additional solid cellulose foam sections 530 have lengths l1, w2, and h2. a , width w a , and height h aThe solid cellulose foam sections 510, 520, and 530 have the same length, width, and height. A rectangular parallelepiped shape is preferred for applications in which the solid cellulose foam body 500 has the shape of a slab. Depending on the shape of the solid cellulose foam body, it is often advantageous from a process standpoint to produce solid cellulose foam sections that are identical to one another in composition, size, and shape. This lack of variability between the produced bodies facilitates large-scale manufacturing. In the embodiment shown in FIG. 2, bonding occurs over the entire surface area of ​​the connecting surfaces 511, 512, 521, 522, 531, 532 of adjacent solid cellulose foam bodies 510, 520, 530. The connecting surfaces 511, 512, 521, 522, 531, 532 of the first solid cellulose foam portion 510, the second solid cellulose foam portion 520, and the two additional cellulose foam portions 530 are all disposed along the length of the solid cellulose foam portions 510, 520, 530 and are all flat. As will be readily understood by those skilled in the art, any number of additional solid cellulose foam portions 530 can be attached to the second connecting surface 532 of one or both of the additional solid cellulose foam portions 530 attached to the first or second solid cellulose foam portions 510, 520. In such embodiments, bonding occurs between the connecting surfaces 531, 532 of adjacent additional solid cellulose foam portions 530.

[0074] In one embodiment, as shown in Figure lb, the solid cellulose foam sections 210, 220, and 230 are different sizes and shapes. This is advantageous when a more complex shape of the solid cellulose foam body 200 is required, such as for certain packaging applications. In this embodiment, bonding occurs only in the overlapping surface areas of the connecting surfaces of adjacent solid cellulose foam sections 210, 220, 230.

[0075] 1a-d and 2, to minimize uneven shrinkage during drying, it is preferred that each solid cellulose foam portion 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 have a width that is comparable to its height. Preferably, the width of each solid cellulose foam portion 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 is in the range of 0.8 to 1.2 times its height, such as 0.9 to 1.1 times, or 0.95 to 1.05 times. The width and height of each solid cellulose foam segment 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 can be equal. The length of each solid cellulose foam segment 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 can have any length, and each solid cellulose foam segment 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 can, for example, be substantially longer than its width.

[0076] In one embodiment, as shown in Figure 1d, multiple identical rectangular shaped solid cellulose foam sections 410, 420, 430 are assembled into a slab-shaped solid cellulose foam body 400. The width w of the solid cellulose foam body 400 is o is equal to the sum of the widths of all the individual solid cellulose foam portions 410, 420, 430. The length l of the solid cellulose foam object 400 o and height h ois the same as that of the individual solid cellulose foam portions 410, 420, 430. The length and width dimensions of such a cellulose foam plank 400 can range from, for example, 100 to 400 cm, such as at least 60 x 60 cm, or at least 100 x 100 cm, or at least 200 x 200 cm, or at least 300 x 300 cm. The height, i.e., thickness, of the foam plank can range from 1 to 20 cm, preferably 1 to 10 cm, and more preferably 4 to 6 cm. The assembled plank can then be cut into smaller foam articles of any size and shape.

[0077] Alternatively, if a solid cellulose foam plank of these dimensions were prepared using a single deposition of wet cellulose foam, non-uniform shrinkage would be expected, potentially resulting in a thickness variation in the resulting solid foam plank along its length and / or width. By instead preparing multiple smaller sized solid cellulose foam sections 410, 420, 430 and subsequently assembling them into the foam plank 400, the problem of non-uniform shrinkage is avoided, resulting in a plank 400 with consistent thickness. Because the solid cellulose foam sections 410, 420, 430 all have a rectangular parallelepiped shape with a width similar to their height, non-uniform shrinkage during drying of the wet cellulose foam used to form the solid cellulose foam sections 410, 420, 430 is largely avoided. This is due to the high surface area-to-height ratio, which distributes tension during drying. Thus, the present invention provides an improved, dimensionally stable solid cellulose foam plank 400. The thickness (i.e., height) of the foam plank 400 is uniform and does not vary along its length and width.

[0078] As will be appreciated by those skilled in the art, the size of the solid cellulose foam body 400 can be adjusted by selecting the length of the solid cellulose foam sections 410, 420, 430 as well as the total number of additional solid cellulose foam sections 430 used in assembling the solid cellulose foam body 400.

[0079] The drying time for small portions of wet cellulose foam is shorter than the drying time for large objects of wet cellulose foam, and therefore the total drying time for an object of a particular size is reduced by drying the smaller cellulose foam portions 410, 420, 430 individually but simultaneously and then assembling them into the object, compared to preparing and drying the object directly as a single unit.

[0080] Solid cellulose foam body 400 includes a total of eight solid cellulose foam sections 410, 420, 430. Thus, solid cellulose foam body 400 includes a total of seven internal interfaces, which means that the stiffness of solid cellulose foam body 400 will be increased compared to an integrally formed solid cellulose foam body, further improving the mechanical properties of solid cellulose foam body 400.

[0081] In an alternative embodiment of the invention, as discussed with respect to Figures 3a-b, 4a-b, and 5a-b, the first connecting surface 611, 711, 811 of the first solid cellulose foam portion 610, 710, 810 includes at least one protruding portion 615, 715, 815, and the first connecting surface 621, 721, 821 of the second solid cellulose foam portion 620, 720, 820 includes at least one recess 625, 725, 825, which is configured to accommodate the protruding portion 615, 715, 815. Thus, the first connecting surface 611, 711, 811 of the first solid cellulose foam portion 610, 710, 810 and the first connecting surface 621, 721, 821 of the second solid cellulose foam portion 620, 720, 820 are complementary to each other. By providing the connecting surfaces 611, 621, 711, 721, 811, 821 with complementary shapes that include protruding portions 615, 715, 815 and recessed portions 625, 725, 825, a stronger bond can be achieved. The shapes of the connecting surfaces 611, 621, 711, 721, 811, 821 of the solid cellulose foam portions 610, 620, 710, 720, 810, 820 are selected to minimize uneven shrinkage of the wet cellulose foam during drying of the wet foam portions. After assembly of the solid cellulose foam body 600, 700, 800, there are no internal voids, meaning that the recesses 625, 725, 825 are configured to have a size and shape that exactly matches the size and shape of the protruding portions 615, 715, 815.

[0082] The attachment of the first connecting surfaces 611, 621, 711, 721, 811, 821 of the first and second solid cellulose foam sections 610, 620, 710, 720, 810, 820 forms an interface that provides stiffness and therefore improved mechanical properties to the assembled solid cellulose foam body 600, 700, 800. Depending on the shape, size, and number of the protruding portions 615, 715, 815 and recessed portions 625, 725, 825, the mechanical properties can be fine-tuned. Preferably, a dense layer is present on the first connecting surfaces 611, 621, 711, 721, 811, 821 to further improve the mechanical properties.

[0083] The protruding portions 615, 715, 815 on the first connecting surface 611, 711, 811 of the first solid cellulose foam portion 610, 710, 810 can have any suitable size and shape. For example, the protruding portions 615, 715, 815 and corresponding recesses 625, 725, 825 can have a rectangular parallelepiped shape, a triangular shape, or a cylindrical shape. Preferably, the recesses 625, 725, 825 do not extend the entire height of the second cellulose foam portion 620, 720, 820. In other words, the height of the protruding portion(s) 615, 715, 815 is preferably less than the height of the second solid cellulose foam portion 620, 720, 820. Thus, when the solid cellulose foam body 600, 700, 800 is assembled, the recesses 625, 725, 825 and protruding portions 615, 715, 815 are not visible on the top and bottom surfaces of the solid cellulose foam body 600, 700, 800. To minimize uneven shrinkage during drying, the width of each protruding portion 615, 715, 815 is preferably comparable to its height. For example, the width of each protruding portion 615, 715, 815 can range from 0.8 to 1.2 times its height, e.g., 0.9 to 1.1 times, or 0.95 to 1.05 times its height. The width is measured at the widest point of the protruding portion 615, 715, 815, and the height is measured at the highest point.

[0084] In embodiments where multiple protruding portions 615, 715, 815 are present, the size and shape of all protruding portions 615, 715, 815 may be the same or may vary in different portions of the first solid cellulose foam portion 610, 710, 810. It is preferred that each protruding portion 615, 715, 815 have the same size and shape as this simplifies manufacturing.

[0085] The number of protruding portions 615, 715, 815 can vary depending on the size and shape of the protruding portions 615, 715, 815 and the size and shape of the first solid cellulose foam portion 610, 710, 810.

[0086] The protruding portions 615, 815 may be in the form of individual units having a length dimension approximately equal to their height and width, and may be regularly arranged on the first connecting surface 611, 811 of the first solid cellulose portion 610, 810 (as shown in Figures 3a-b and 5a-b). Such protruding portions 615, 815 may be in the form of a rectangular parallelepiped, a pyramidal, a cylindrical, or any other suitable shape. In the embodiment shown in Figure 3a, all four protruding portions 615 of the first connecting surface 611 are in the form of rectangular parallelepiped pillars of the same size. Accordingly, the corresponding recesses 625 are in the form of rectangular parallelepiped recesses.

[0087] In some embodiments of the present invention, as shown in Figures 4a and 5a, the first connecting surfaces 711, 721, 811, 821 of the first solid cellulose foam body 710, 810 and the second solid cellulose foam body 720, 820 include at least one protruding portion 715, 815 and at least one recessed portion 725, 825. In such embodiments, the surface area of ​​the foam portions is increased, resulting in faster drying times.

[0088] In one embodiment, as shown in Figures 4a-b, each protruding portion 715 and each recessed portion 725 extends along the entire length of the first solid cellulose foam portion 710 and the second solid cellulose foam portion 720, respectively. Alternatively, each protruding portion and each recessed portion can extend along the entire width of the first solid cellulose foam portion 710 and the second solid cellulose foam portion, respectively. In the embodiment shown in Figure 4a, the first connecting surfaces 710, 720 of the first and second solid cellulose foam portions include both protruding portions 715 and recessed portions 725 that extend along the length of the first and second solid cellulose foam portions. Cross sections of the first and second solid cellulose foam portions taken perpendicular to the length of the extending protruding portions and recessed portions show that the first and second connecting surfaces have a sinusoidal shape. The first solid cellulose foam portion 710 is complementary to the second solid cellulose foam portion 720. Once assembled, there are no gaps between the first and second solid cellulose foam portions 710, 720, as shown in Figure 4b, which shows a side view of the assembled solid cellulose foam object 700. An advantage of the embodiment shown in Figures 4a and 4b is that the sinusoidal shape of the protruding portions 715 and recessed portions 725 of the first and second connecting surfaces 711, 721 increases surface area, leading to faster drying times. The sinusoidal shape of the tension distribution within the connecting surfaces also minimizes uneven shrinkage during drying.

[0089] In embodiments in which the first and second connecting surfaces 711, 721 include at least one protruding portion 715 and at least one recessed portion 725 extending along the length or width of the first and second solid cellulose foam portions 710, 720, the first and second connecting surfaces 711, 721 may have a corrugated shape when viewed in a cross section of the first and second solid cellulose foam portions 710, 720 cut perpendicular to the direction of the extending protruding portion 715 and recessed portion 725. The corrugation is preferably periodic and may be selected from a sinusoidal wave (as shown in Figures 4a-b), a square wave, a sawtooth wave, or a triangular wave.

[0090] In one embodiment, as shown in Figure 5a, the connecting surfaces 811, 821 of the first solid cellulose foam portion 810 and the second solid cellulose foam portion 820 include regularly spaced protrusions 815 and recesses 825 in the shape of rectangular pillars. Because the connecting surfaces 811, 821 are complementary to each other, no gaps exist between the first solid cellulose foam portion 810 and the second solid cellulose foam portion 820 after assembly into the solid cellulose foam object 800, as shown in Figure 5b. Such an embodiment may be preferred because it minimizes uneven shrinkage of the wet foam shape during drying due to the distribution of tension forces.

[0091] In embodiments of the invention in which the first connecting surfaces 611, 711, 811 of the first and second solid cellulose foam sections 610, 620, 710, 720, 810, 820 are provided with protruding portions 615, 715, 815 and recessed portions 625, 725, 825, respectively, the other surfaces of the first and second solid cellulose foam sections 610, 620, 710, 720, 810, 820 are preferably flat. In such embodiments, the solid cellulose foam article 600, 700, 800 preferably includes only the first and second solid cellulose foam sections 610, 620, 710, 720, 810, 820, and does not include any additional solid cellulose foam sections. Thus, the lengths and widths of the first and second solid cellulose foam portions 610, 620, 710, 720, 810, 820 correspond to the length and width of the assembled solid cellulose foam body 600, 700, 800. Optionally, additional solid cellulose foam portions may be attached to the second connecting surfaces of the first and / or second solid cellulose foam portions 610, 620, 710, 720, 810, 820. Alternatively, the second connecting surfaces of the first and / or second cellulose foam portions 610, 620, 710, 720, 810, 820 may also have protrusions and / or recesses for attachment to the first connecting surfaces of the additional solid cellulose foam portions, the connecting surfaces having protrusions and / or recesses configured to correspond to the protrusions and / or recesses of the connecting surfaces to which they are attached.

[0092] According to a second aspect, the present invention relates to a method for producing a solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 comprising at least two separate solid cellulose foam portions. The method according to the second aspect can be used to produce a solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 according to the first aspect.

[0093] The method according to the second aspect comprises the steps of: - providing at least one wet cellulose foam; - forming and drying the wet cellulose foam to obtain a first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810; a second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820; and, optionally, at least one additional solid cellulose foam portion 230, 330, 430, 530; wherein the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 is a second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 comprising a first connecting surface 521, 621, 721, 821 and optionally a second connecting surface 522; and an optional at least one additional solid cellulose foam portion 230, 330, 430, 530 comprising a first connecting surface 531 and optionally a second connecting surface 532; - attaching a first connecting surface 511, 611, 711, 811 of a first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 to a first connecting surface 521, 621, 721, 821 of a second cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 to obtain a solid cellulose foam object 100, 200, 300, 400, 500, 600, 700, 800; and - optionally attaching the first connecting surface 531 of at least one additional cellulose foam portion 230, 330, 430, 530 to the second connecting surface 512, 522 of the first solid cellulose foam portion and / or the second solid cellulose foam portion 220, 320, 420, 520; Includes:

[0094] In the first step of the method according to the second aspect, at least one wet cellulose foam, the details of which are further described above, is provided. Preferably, the same wet cellulose foam is used to prepare all of the solid cellulose foam portions used in the assembly of the solid cellulose foam object. Alternatively, multiple wet cellulose foams may be provided, with the wet foams differing in properties, such as composition or density.

[0095] In the next step of the method according to the second aspect, the wet cellulose foam is shaped and dried to obtain a solid cellulose foam portion of the desired shape. Shaping can be performed using any suitable means. For example, shaping can be performed using a mold, by forming a deposited wet foam using, for example, a scraper, or by depositing the wet foam into the desired shape, for example, by extrusion. Shaping using a mold is often advantageous when precise shapes are required, such as when forming complex connecting surfaces containing multiple protrusions and recesses (e.g., as shown in Figures 5a-b). Shaping is preferably performed on the wet cellulose foam before drying. In an alternative embodiment, the wet cellulose foam can be shaped by drying it into large sheets and then cutting them into the desired shape. However, this method is not preferred because of the waste of material during cutting.

[0096] In some embodiments, a mold is used to shape the wet cellulose foam. The wet cellulose foam can be placed in a mold having a shape corresponding to the desired shape of the solid cellulose foam portion to be formed. The mold can also be in the form of a frame resting on a surface. The mold can have only an open top or multiple open sides, depending on the shape to be obtained. The mold can also be in the form of a forming belt. The mold can be removed before drying or left in place during drying. Because the wet cellulose foam of the present invention is self-supporting, it will maintain its shape during drying even if the mold is removed before drying. In embodiments in which the wet cellulose foam remains in the mold during drying, the mold is preferably perforated to allow water to evaporate through the mold during drying. Advantages of using a mold for molding include shape fidelity and heat transfer. If the mold remains during drying of the wet cellulose foam, shape accuracy is further improved because shrinkage is minimized.

[0097] In one embodiment, the shaping is performed by directly depositing the wet cellulose foam composition into the desired shape. This can be done, for example, by extrusion using a suitable dispensing means, such as using 3D printing. Because the wet cellulose foam composition is self-supporting, the shape of the wet cellulose foam will be maintained during drying. The ability to deposit the wet cellulose foam as a self-supporting wet foam allows for a great variety of shapes that can be produced.

[0098] In one embodiment, the shaping is achieved by depositing the wet foam on a surface and then scraping the surface of the first and second wet foams. Before the wet foams dry, the surface is shaped into the desired shape. The scraping can be achieved using any suitable means, such as a scraper, blade, or roller. This shaping method can be easily performed on a large scale.

[0099] Shaping can be done in multiple steps, such as by first depositing wet foam on a surface, followed by subsequent deposition of wet foam to obtain the portions that will become the protruding portions after drying. In embodiments where the solid cellulose foam portions have different sizes or shapes, different shaping methods can be employed to obtain the desired shapes.

[0100] The shaping is performed so that the dimensions of the resulting wet cellulose foam portion are optimized to minimize uneven shrinkage during subsequent drying and shorten drying times. This includes, for example, shaping a wet cellulose foam portion having a height that is approximately the same as its width. In embodiments where the connecting surface includes protrusions and / or recesses, the surface area of ​​the foam portion is increased, which is advantageous for shortening drying times. By forming protrusions and / or recesses that are approximately the same in at least two dimensions selected from length, width, and height, uneven shrinkage during drying can be minimized.

[0101] In embodiments using solid cellulose foam sections in the shape of a rectangular parallelepiped, the wet cellulose foam can be formed using a frame placed on a perforated tray, as shown in Figures 1a-d and 2. The wet cellulose foam is deposited inside the frame, and the top is scraped to obtain a smooth surface. Preferably, the frame is left in place while the wet cellulose foam dries to minimize shrinkage and ensure precise dimensional solid cellulose foam sections 110, 120, 210, 220, 230, 310, 320, 330, 410, 420, 430, 510, 520, 530 are obtained.

[0102] In embodiments in which the first connecting surface 611 of the first solid cellulose foam portion 610 includes at least one pillar-shaped protruding portion 615, the protruding portion 615 can be formed, for example, by depositing wet cellulose foam on a wet cellulose foam sheet deposited on a support surface, as shown in Figure 3a. A corresponding recess 625 on the first connecting surface 621 of the second cellulose foam portion 620 can be formed using a mold. Alternatively, the protruding portion 615 can also be formed using a mold.

[0103] In embodiments in which the protruding portions 715 and / or recessed portions 725 extend along the length and / or width of the first and / or second solid cellulose foam portions 710, 720, as shown in FIG. 4a, the wet cellulose foam can be molded using a mold having a corresponding shape, such as by depositing the foam on a molding belt and flattening the top surface of the deposited foam. Depositing the wet foam on a molding belt facilitates scale-up of the process. For example, in embodiments in which the connecting surfaces 711, 721 are corrugated, continuous large-scale production can involve depositing the wet foam on a molding belt having protruding portions and recessed portions extending widthwise and flattening the top surface of the wet foam. Alternatively, molding can be performed by first depositing a wet cellulose sheet on a support surface and then using a scraper or roller to mold the top surface of the wet sheet. This molding method also facilitates scale-up of the process. For example, in embodiments where the connecting surfaces 711, 721 are corrugated, continuous production can involve depositing a sheet of wet foam onto a belt and then using a roller or scraper to shape the top surface of the wet foam sheet to form protrusions and recesses along the length of the foam.

[0104] In embodiments in which both the first connecting surfaces 711, 721 of the first and second solid cellulose foam sections 710, 720 include multiple protrusions 715 and recesses 725 extending along the entire width and length of the solid cellulose foam sections 710, 720, as shown in FIG. 4a, the first and second solid cellulose foam sections 710, 720 may be joined during manufacturing. In such embodiments, the wet cellulose foam is molded into a single large section, for example, by depositing it on a molding belt or using rollers. Preferably, molding is performed so that the top or bottom surface of the wet cellulose foam has a corrugated shape. The molded surfaces will become the connecting surfaces 711, 721 of the dried solid cellulose foam sections 710, 720. After drying, the large foam section is divided, for example, by cutting, to obtain first and second cellulose foam sections 710, 720, which are preferably of equal size. The connecting surfaces 711, 721 of the cellulose foam sections 710, 720 are complementary to each other. Such a process simplifies manufacturing since forming and drying is performed on only one deposit of wet foam instead of two deposits.

[0105] In embodiments where the first connecting surfaces 811, 821 of the first and second solid cellulose foam sections 810, 820 include multiple protrusions 815 and recesses 825 forming a complex shape, as shown in FIG. 5a, shaping is preferably performed by a mold corresponding to the desired shape to ensure that the correct dimensions are maintained.

[0106] The formed wet cellulose foam portion can be dried by evaporation at room temperature or at elevated temperatures, for example, at temperatures between 40°C and 140°C. Any suitable apparatus can be used. After drying, a solid cellulose foam portion is obtained having a shape corresponding to the formed wet cellulose foam portion. If a mold is used for forming, the cellulose foam can be left in the mold during drying, or the mold can be removed before drying. As mentioned above, a dense layer forms on the outer surface of the cellulose foam during drying.

[0107] As discussed above, the wet cellulose foam portion is shaped to provide optimal dimensions to minimize uneven shrinkage during drying of the wet cellulose foam.

[0108] In embodiments in which the first connecting surfaces 611, 621, 711, 721, 811, 821 of the solid cellulose foam sections 610, 620, 710, 720, 810, 820 include protruding portions 615, 715, 815 and / or recessed portions 615, 725, 825, such a design distributes the increased tension that occurs during drying of the foam, minimizing capillary pressure and therefore uneven shrinkage. In embodiments in which all connecting surfaces of the solid cellulose foam sections are flat, uneven shrinkage of the wet cellulose foam sections during drying can be minimized by having the width of the wet cellulose foam sections be comparable to its height.

[0109] Optionally, the solid cellulose foam sections may be cut after drying and prior to assembly of the solid cellulose foam body. For example, in embodiments where the solid cellulose foam sections 210, 220, 230 are different sizes, as shown in FIG. 1b, the solid cellulose foam sections 210, 220, 230 can be cut to obtain the desired length. In large-scale manufacturing, rods of solid foam are continuously produced and then cut to obtain solid cellulose foam sections of suitable length for assembling a structure according to the embodiment shown in FIGS. 1 and 2.

[0110] After drying, the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 is attached to the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 to obtain the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800. Optionally, at least one additional solid cellulose foam portion 230, 330, 430, 530 may be attached to the first and / or second solid cellulose foam portions. In preferred embodiments, bonding occurs along the entire connecting surface. In other embodiments, bonding occurs along only a portion of the connecting surface. The connecting surface preferably exists along the entire length of the solid cellulose foam portion. The bonding step includes contacting the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 with the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820. An adhesive or other bonding means can be disposed between the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 and the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820. Additional solid cellulose foam sections 230, 330, 430, 530 may be attached in a similar manner.

[0111] In some embodiments, pressure can be applied during the bonding step. Applying pressure during the bonding step ensures that the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 and the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 adhere to one another to ensure a strong bond. Pressure can be applied using any suitable pressure means, such as a roller, bar, or plate. Pressure can be applied to one, some, or all of the attached solid cellulose foam portions. In embodiments in which additional solid cellulose foam portions are attached, pressure can be applied after each additional solid cellulose foam portion 230, 330, 430, 530 is attached, or after all of the additional solid cellulose foam portions 230, 330, 430, 530 have been attached.

[0112] The bonding step typically involves manually or automatically placing one solid cellulose foam section in intimate contact with another solid cellulose foam section. Any suitable device known to those skilled in the art can be used. For example, the first solid cellulose foam section 110, 210, 310, 410, 510, 610, 710, 810 can be positioned with the first connecting surface 511, 611, 711, 811 facing upward. An adhesive may then be applied to the first connecting surface 511, 611, 711, 811 before positioning the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820 onto the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810. Pressure may then be applied, for example, by passing the assembled solid cellulose foam body under a pressure-applying roller.

[0113] The attaching step can include any suitable adhesive means. In some embodiments, the attaching step includes applying an adhesive to at least one connecting surface prior to attaching the first solid cellulose foam section 110, 210, 310, 410, 510, 610, 710, 810, the second solid cellulose foam section 120, 220, 320, 420, 520, 620, 720, 820, and optionally at least one additional solid cellulose foam section 230, 330, 430, 530. Curing of the adhesive can occur at room temperature or at an elevated temperature, depending on the type of adhesive. Preferably, curing occurs at room temperature.

[0114] Any suitable adhesive can be used in the present invention. In some embodiments, the adhesive is selected from hot melt adhesives, wood adhesives, starch-based adhesives, carboxymethyl cellulose (CMC), polyvinyl acetate, ethylene vinyl acetate, casein, latex, polyurethane, dextrin, and gums such as guar gum and xanthan gum. The adhesive is preferably water-based and / or bio-based.

[0115] The adhesive can be applied to the connecting surfaces of the solid cellulose foam portions using any suitable coating method, such as roller coating, blade / knife coating, brushing, flexo roller, spray coating, etc. In some embodiments, the adhesive is applied to the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 or the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820. In some embodiments, adhesive is applied to both the first connecting surface 511, 611, 711, 811 of the first solid cellulose foam portion 110, 210, 310, 410, 510, 610, 710, 810 and the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam portion 120, 220, 320, 420, 520, 620, 720, 820. A stronger and more durable connection may be obtained if adhesive is applied to both connecting surfaces. Similarly, in embodiments in which the solid cellulose foam article 100, 200, 300, 400, 500, 600, 700, 800 includes at least one additional solid cellulose foam portion 230, 330, 430, 530, adhesive can be applied to the second connecting surface 512, 522 of the first and / or second solid cellulose portion 210, 220, 310, 320, 410, 420, 510, 520 and / or the first connecting surface 531 of the at least one additional solid cellulose foam portion 530.

[0116] In some embodiments, the adhesive means comprises a double-sided adhesive tape, the tape being disposed on the connecting surface of the solid cellulose foam portion.

[0117] In embodiments in which the solid cellulose foam includes CMC, the attaching step can include applying water to the connecting surfaces. The water partially dissolves the outer surface of the connecting surfaces of the solid cellulose foam sections, exposing the CMC and providing adhesive properties. For example, the first connecting surface 521, 621, 721, 821 of the second solid cellulose foam section 120, 220, 320, 420, 520, 620, 720, 820 can be attached to the partially dissolved first connecting surface 511, 611, 711, 811 of the first solid cellulose foam section 120, 220, 320, 420, 520, 620, 720, 820.

[0118] In some embodiments, the attaching step can include applying a thin layer of wet cellulose foam. Using a thin layer of wet foam for attachment results in a solid cellulose foam object 100, 200, 300, 400, 500, 600, 700, 800 that includes only cellulose foam and no other materials, such as adhesives.

[0119] In embodiments in which additional solid cellulose foam sections 230, 330, 430, 530 are attached, the adhesive means can be selected from the same as those described above. The same adhesive means can be used to attach all of the solid cellulose foam sections used to assemble the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800. Alternatively, different adhesive means can be used to attach the solid cellulose foam sections within the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800.

[0120] In embodiments in which the first connecting surfaces 611, 621, 711, 721, 811, 821 of the first and second solid cellulose foam portions 610, 620, 710, 720, 810, 820 include at least one complementary protruding portion 615, 715, 815 and / or recessed portion 625, 725, 825, the bonding comprises mating the first and second solid cellulose foam portions 610, 620, 710, 720, 810, 820 with one another such that the recessed portion(s) 625, 725, 825 receive the protruding portion(s) 615, 715, 815. In some embodiments, the first and second solid cellulose foam portions 810, 820 can be attached by simply mating the protruding portion 815 with the recessed portion 825, as shown in Figures 5a and 5b. Other bonding means, such as adhesives, are also required to provide a strong and durable bond and therefore a more stable solid cellulose foam body 800 .

[0121] The assembled solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 of the present invention may be cut into pieces of any desired size.

[0122] In some embodiments, an additional substrate is attached to the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800. Such a substrate can improve the stability and mechanical properties of the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800 and facilitate further handling and processing, such as converting operations. The substrate can be selected from, for example, paper or paperboard.

[0123] In some embodiments, a coating can be applied to any surface of the solid cellulose foam body 100, 200, 300, 400, 500, 600, 700, 800, and / or one or more solid cellulose foam portions. The coating is preferably applied in the form of a liquid coating composition, and one or more coating layers can be applied. The coating layers can have the same or different compositions. The coating can include at least one particulate material or at least one particulate material and at least one film-forming material. The particulate material can be selected from at least one of microfibrillated cellulose (MFC), cellulose fibers, or mineral particles such as clay or calcium carbonate. In the context of this patent application, MFC refers to cellulose particles, fibers, or fibrils having a width or diameter between 20 nm and 1000 nm. The film-forming material can be selected from at least one of carboxymethyl cellulose (CMC), cellulose ethers, starch, polyvinyl alcohol, or synthetic latexes such as acrylic or styrene-butadiene latexes. The coating may be selected from, for example, at least one of a wax such as beeswax or carnauba, an alkyl ketene dimer (AKD), or an alkyl succinic anhydride (ASA).

[0124] The application of a coating reduces the breathability of the solid cellulose foam by blocking the pores on the surface of the foam. This facilitates various processing and conversion operations, including vacuum. Additionally, depending on the type of coating, properties such as strength and hydrophobicity of the solid cellulose foam can be altered by the application of the coating. The coating is preferably applied to the surface of the foam, including the dense layer.

[0125] The coating composition can be applied using any suitable method used for coating, such as roller coating, blade / knife coating, brushing, flexographic roller, and spray coating. [Example]

[0126] Example 1 - Preparation of Wet Cellulose Foam Wet cellulose foams with a dry content of 15.8% were prepared. All wet foam compositions consisted of 10 wt% CMC, 1 wt% surfactant, and 89 wt% cellulose fiber, based on the total weight of the wet foam composition's solids content. Cellulose fiber (125 g, softwood bleached kraft pulp fiber) was milled in 700 mL of water using a Kenwood Chef XL Titanium mixer equipped with a K-beater. After the cellulose fiber suspension was properly pulped, CMC (13.5 g) was added as a dry powder and mixed using a K-beater until a homogeneous mixture was achieved. A surfactant solution (20 wt%) containing a 1:1 molar ratio of sodium cocoyl sarcosinate to myristic acid was then added to the cellulose fiber / CMC solution mixture (8 ml). The mixture was then aerated using the Kenwood mixer's balloon whipper until the desired amount of air was mechanically introduced into the mixture. After mixing, the foam was collected in a 250 ml plastic cup and the density was measured (target density was 188 kg / m 3 was).

[0127] Example 2 - Preparation of rod-shaped foam sections The wet cellulose foam of Example 1 was molded using two perforated metal sheets. The metal sheets measured 10 cm x 36 cm and were bent along the center of their length to create two L-shaped trays with a base of 5 cm, a height of 5 cm, and a length of 36 cm. The two trays were filled with wet foam and combined to create a perforated metal mold measuring 5 x 5 x 36 cm. The wet cellulose foam in the mold was dried in a convection oven at 120°C. The foam remained in the mold during drying. The foam was weighed multiple times during drying. The resulting drying curve is shown in Figure 6 (5 x 5 rod). The drying rate was increased compared to a wider foam with the same height and length due to more efficient heating from all directions and an increased surface area to volume ratio. After drying, a solid cellulose foam portion in the shape of a rod measuring 5 x 5 x 36 cm was obtained. Because the wet foam was restrained by the mold during drying, no shrinkage was observed.

[0128] Multiple rods could be glued together to form large cellulose foam planks.

[0129] Example 3 - Preparation of a Sine Wave Shaped Foam Section The wet cellulose foam of Example 1 was deposited in a frame (24.5 x 44 cm x 5 cm) placed on a surface. A sine-shaped wooden scraper was used to scrape off the top surface of the deposited wet foam, resulting in a wet foam with a sine-wave shape with hills (protrusions) and valleys (depressions). The height of the protrusions was 4 cm, and the distance between adjacent peaks of the waveform was 6 cm. The depressions did not extend throughout the entire wet foam. Molding was performed in either the width or length direction. The molded wet cellulose foam was dried in a convection oven at 120°C. The foam was weighed multiple times during drying. The resulting drying curve is shown in Figure 6 (sine-wave foam). Compared to a reference foam of similar dimensions, the drying rate was improved. The valleys dried faster due to their low height, and the hills would behave like individual units with large surface areas during drying. Therefore, the sinusoidal foam dried faster. The sinusoidal shape of Example 3 has a greater surface area to volume ratio than the rod shape of Example 2, so the foam with the sinusoidal shape dries faster.

[0130] Some shrinkage was observed during drying, but the shrinkage was uniform and two sinusoidal shaped foam pieces could be glued together to produce a rectangular foam article.

[0131] Example 4 - Preparation of Triangular Shaped Foam Section The wet cellulose foam of Example 1 was deposited in a frame placed on a surface. A perforated metal sheet was bent to obtain a triangular wave shape, with the triangular shape extending along the width of the metal sheet. The bent metal sheet, along with a wooden frame (24 × 30 × 5 cm), was used as a mold onto which the wet cellulose foam was deposited. In this way, the bottom surface of the wet cellulose foam deposit was shaped. The top surface was scraped off to obtain a flat surface. The wet cellulose foam in the mold was dried at 120 °C in a convection oven. The foam remained in the mold during drying. The foam was weighed multiple times during drying. The resulting drying curve is shown in Figure 6 (triangle). The drying rate was improved compared to a reference foam of similar dimensions. The lower part of the triangular shape dries faster due to the thinner foam. The inside of the triangular shape dries faster due to the increased surface area. The drying rate of the triangular wave shaped foam is similar to that of the sinusoidal wave shaped foam.

[0132] During drying, the wet foam remained in the mold, so shape retention was good and no shrinkage was observed. By adhering two triangular shaped foam pieces together, a rectangular shaped foam article could be produced.

[0133] Example 5 (Comparative) - Preparation of Foam Sheet The wet cellulose foam of Example 1 was deposited in a frame (24.5 cm x 44 cm) placed on a surface. The foam thickness was 5 cm. The wet cellulose foam in the frame was dried in a convection oven at 120°C. The foam remained in the frame during drying. The foam was weighed multiple times during drying. The resulting drying curve is shown in Figure 6 (reference). Due to the uniform thickness and low surface area to volume ratio compared to the other foams, the drying time is significantly longer compared to the geometries of Examples 3, 4, and 5.

[0134] Non-uniform shrinkage was observed along the height, with the center of the dried foam sheet being thinner than the thickness along the edges.

[0135] It will be apparent to those skilled in the art in view of the above detailed description of the invention that other modifications and variations will be apparent to those skilled in the art, and that such other modifications and variations are possible without departing from the spirit and scope of the invention.

Claims

1. Solid cellulose foam material (100, 200, 300, 400, 500, 600, 700, 800), A first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810) including a first connecting surface (511, 611, 711, 811) and optionally a second connecting surface (512), A second solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820) including a first connecting surface (521, 621, 721, 821) and optionally a second connecting surface (522) Includes, The first connecting surfaces (511, 611, 711, 811) of the first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810) and the first connecting surfaces (521, 621, 721, 821) of the second solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820) are attached to each other to form a solid cellulose foam object (100, 200, 300, 400, 500, 600, 700, 800). The solid cellulose foam material (100, 200, 300, 400, 500, 600, 700, 800) optionally includes at least one additional solid cellulose foam portion (230, 330, 430, 530) having a first connecting surface (531) and optionally a second connecting surface (532), wherein the first connecting surface (531) of at least one additional solid cellulose foam portion (230, 330, 430, 530) is attached to the second connecting surfaces (512, 612, 712, 812, 522, 622, 722, 822) of the first solid cellulose foam portion (210, 310, 410, 510) and / or the second solid cellulose foam portion (220, 320, 420, 520). Solid cellulose foam material.

2. The solid cellulose foam material according to claim 1, wherein the solid cellulose foam material (100, 200, 300, 400, 500, 600, 700, 800) is essentially rigid.

3. The density of solid cellulose foam materials (100, 200, 300, 400, 500, 600, 700, 800) is 10-80 kg / m³. ３ A solid cellulose foam object according to claim 1 or 2, which is within the range of the specified object.

4. The solid cellulose foam according to claim 1 or 2, wherein the first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810), the second solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820), and at least one optional additional solid cellulose foam portion (230, 330, 430, 530) contain cellulose fibers in the range of 71 to 95% by weight, based on the total dry weight of the solid cellulose foam.

5. The solid cellulose foam according to claim 1 or 2, wherein the first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810), the second solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820), and at least one optional additional solid cellulose foam portion (230, 330, 430, 530) all contain cellulose fibers in the range of 71 to 95% by weight based on the total dry weight of the solid cellulose foam, a water-soluble thickener in the range of 4 to 24% by weight based on the total dry weight of the solid cellulose foam, and at least two surfactants.

6. Solid cellulose foam material (100, 200, 300, 400, 500, 600, 700, 800) with length l ｏ , width w ｏ , and height h ｏ A solid cellulose foam object according to claim 1 or 2, having the shape of a rectangular parallelepiped.

7. The first solid cellulose foam portion (110, 210, 310, 410, 510) has a length l １ , width w １ , and height h １ and is in the shape of a rectangular parallelepiped; the second solid cellulose foam portion (120, 220, 320, 420, 520) has a length l ２ , width w ２ , and height h ２ and is in the shape of a rectangular parallelepiped, and optionally at least one additional solid cellulose foam portion (230, 330, 430, 530) has a length l ａ , width w ａ , and height h ａ and is in the shape of a rectangular parallelepiped, preferably the dimensions of the first solid cellulose foam portion (110, 310, 410, 510), the second solid cellulose foam portion (120, 320, 420, 520) and the optionally at least one additional solid cellulose foam portion (330, 430, 530) are the same. The solid cellulose foam article according to claim 1 or 2.

8. The solid cellulose foam body according to claim 7, wherein the first connecting surfaces (511, 521, 531) and optional second connecting surfaces (512, 522, 532) are arranged along the lengths of the first solid cellulose foam portion (110, 210, 310, 410, 510), the second solid cellulose foam portion (120, 220, 320, 420, 520), and at least one optional additional solid cellulose foam portion (230, 330, 430, 530), respectively.

9. The solid cellulose foam object according to claim 1 or 2, wherein the first connecting surface (611, 711, 811) of the first solid cellulose foam portion (610, 710, 810) includes at least one protruding portion (615, 715, 815), and the first connecting surface (621, 721, 821) of the second solid cellulose foam portion (620, 720, 820) includes at least one recess (625, 725, 825), and the at least one recess (625, 725, 825) is configured to accommodate the protruding portion (615, 715, 815).

10. The solid cellulose foam object according to claim 9, wherein the first connecting surfaces (711, 721, 811, 821) of both the first solid cellulose foam portion (710, 810) and the second solid cellulose foam portion (720, 820) include at least one protruding portion (715, 815) and at least one recess (725, 825).

11. The solid cellulose foam according to claim 9, wherein each protruding portion 715 and each recessed portion 725 extends along the entire width or length direction of the first solid cellulose portion 710 and the second solid cellulose portion 720, respectively.

12. The solid cellulose foam object according to claim 11, wherein in the cross-sections of the first and second solid cellulose foam portions 710 and 720 cut perpendicular to the direction of the extending protruding portion 715 and recessed portion 725, the first and second connecting surfaces 711 and 721 have a corrugated shape.

13. The solid cellulose foam material according to claim 11, wherein the waveform is selected from a sine wave, a square wave, a sawtooth wave, or a triangular wave.

14. A method for producing solid cellulose foam (100, 200, 300, 400, 500, 600, 700, 800), - The step of providing at least one wet cellulose foam; - A step of forming and drying a wet cellulose foam to obtain a first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810), a second solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820), and optionally at least one additional solid cellulose foam portion (230, 330, 430, 530); the first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810) is first connected The steps include obtaining each foam portion comprising: a first solid cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820) comprising a first connecting surface (521, 621, 721, 821) and optionally a second connecting surface (522); and an optional additional solid cellulose foam portion (230, 330, 430, 530) comprising a first connecting surface (531) and optionally a second connecting surface (532); - The steps of obtaining a solid cellulose foam object (100, 200, 300, 400, 500, 610, 710, 800) by attaching the first connecting surfaces (511, 611, 711, 811) of the first solid cellulose foam portion (110, 210, 310, 410, 510, 610, 710, 810) to the first connecting surfaces (521, 621, 721, 821) of the second cellulose foam portion (120, 220, 320, 420, 520, 620, 720, 820); - The step of optionally attaching the first connecting surface (531) of at least one additional cellulose foam portion (230, 330, 430, 530) to the second connecting surface (512, 522) of the first solid cellulose foam portion (210, 310, 410, 510) and / or the second solid cellulose foam portion (220, 320, 420, 520). A method that includes this.

15. The method according to claim 14, wherein at least one wet cellulose foam comprises, on a basis of the total weight of the wet cellulose foam, 10 to 38% by weight of cellulose fibers, 0.5 to 10% by weight of a water-soluble thickener, and 0.1 to 2% by weight of a surfactant.

16. Wet cellulose foam, 120-500 kg / m³ ３ The method according to claim 15, having a density and a yield strength of at least 80 Pa.

17. The method according to any one of claims 14 to 16, wherein the molding step is carried out so that the obtained first solid cellulose foam portions (110, 210, 310, 410, 510), second solid cellulose foam portions (120, 220, 320, 420, 520), and at least one optional additional solid cellulose foam portion (230, 330, 430, 530) are all in the shape of a rectangular parallelepiped.

18. The method according to any one of claims 14 to 16, wherein the molding step is carried out such that the first connecting surface (611, 711, 811) of the obtained first solid cellulose foam portion (610, 710, 810) includes at least one protruding portion (615, 715, 815), and the first connecting surface (621, 721, 821) of the second solid cellulose foam portion (620, 720, 820) includes at least one recess (625, 725, 825) configured to accommodate at least one protruding portion (615, 715, 815).

19. The method according to claim 18, wherein the molding step is carried out such that the first connecting surfaces (711, 721, 811, 821) of both the first solid cellulose foam portion (710, 810) and the second solid cellulose foam portion (720, 820) include at least one protruding portion (715, 815) and at least one recessed portion (725, 825).

20. The method according to claim 18, wherein the molding step is carried out such that each protruding portion (715) and each recess (725) extends along the entire length or width of the first solid cellulose foam portion (710) and the second solid cellulose foam portion (720).

21. The method according to claim 20, wherein in cross-sections of the first and second solid cellulose foam portions (710, 720) cut perpendicular to the direction of the extending protruding portion (715) and recessed portion (725), the first and second connecting surfaces (711, 721) are molded to have a corrugated shape.

22. The method according to claim 21, wherein the waveform is selected from a sine wave, a square wave, a sawtooth wave, and a triangular wave.

23. The method according to claim 18, wherein the installation step includes placing at least one protruding portion (615, 715, 815) of the first connecting surface (611, 711, 811) of the first solid cellulose foam portion (610, 710, 810) into the corresponding at least one recess (625, 725, 825) of the first connecting surface (621, 721, 821) of the second solid cellulose portion (620, 720, 820).

24. The method according to any one of claims 14 to 16, wherein the attachment step includes applying adhesive to at least one connecting surface (511, 611, 711, 811, 512, 521, 621, 721, 821, 522, 531, 532) before attaching the first solid cellulose foam portion (110, 210, 310, 420, 520, 620, 720, 820) and at least one optional additional solid cellulose foam portion (230, 330, 430, 530).

25. Use of the solid cellulose foam (100, 200, 300, 400, 500, 600, 700, 800) according to claim 1 or 2 as a packaging material, building material, heat insulation material, acoustic insulation material, or plant growth medium for hydroponics.

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