Method for forming solid cellulose foam

Abstract

The present invention relates to a method for forming at least one compressed region in a solid cellulose foam, the method comprising the steps of: a) providing a solid cellulose foam; b) providing at least one cutting line of a predetermined cutting depth on at least one surface of the solid cellulose foam, the at least one cutting line defining at least one pattern on the at least one surface; and c) pressing at least one pressing tool into the at least one pattern on the at least one surface of the cellulose foam, thereby forming at least one compressed region. The present invention also relates to a solid cellulose foam product formed by this method.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a solid cellulose foam intended to be a packaging material for goods during storage and transport.

[0002] The present invention also relates to articles of manufacture comprising the formed solid cellulose foam. [Background technology]

[0003] Virtually all consumer goods require protective packaging to protect the item during storage and transportation. It is recognized that there are many solutions for packaging and cushioning various items, depending on the physical characteristics of the item to be protected and the degree of protection required in relation to its use.

[0004] Examples of these are polymer foam materials for packaging, such as polyurethane foam (PU), polyethylene foam (PE), expanded polystyrene (EPS) or expanded polypropylene (EPP). Porous materials for this type of use must be stable, lightweight and easy to manufacture. Due to the increasing awareness of the need to use renewable materials, there is a great drive to replace petroleum-derived polymers with polymers derived from renewable resources.

[0005] Finding foam materials from renewable resources presents many challenges. Many bio-based foams have higher production costs, lower mechanical performance, and lower stability in water and at high temperatures compared to existing foams from petroleum-based resources. Bio-based, recyclable protective materials must possess the same superior characteristics and properties as petroleum-based materials to be the first choice over petroleum-based materials.

[0006] The low weight and good impact absorption of bio-based foams are examples of important features. Also, the ability to customize the shape and form of the bio-based foam to that of the product to be protected by the protective material is of utmost importance. Cellulose has been shown to be the most abundant renewable natural polymer on Earth, with its crystalline structure and the availability of methods for its preparation in large quantities on an industrial scale.

[0007] Several bio-based foams containing cellulose have been described. WO20200011587 describes a porous material prepared by aerating a paste containing cellulose fibers and gluten and depositing the aerated paste into a dried mold. WO2015036659 describes a molded fiber product prepared by foaming an aqueous suspension of natural fibers in combination with synthetic fibers and a surfactant, feeding the fiber foam into a mold, and drying it to produce a dry fiber product.

[0008] There remains a need for natural, bio-based, and recyclable protection and cushioning materials that are fully recyclable within the normal paper and board flow and can become part of a circular material flow within existing packaging waste management systems. Protection and cushioning materials need to be compatible with a variety of conversion methods and designed to fit the complex shapes of the goods to be protected, allowing for optimized cushioning and packaging sizes. Summary of the Invention

[0009] The object of the present invention is to obviate at least some of the drawbacks of the prior art and to provide a method for forming at least one compressed region in a solid cellulose foam, as defined in claim 1.

[0010] By the method of claim 1, formed solid cellulose foams tailored to protect goods of any shape can be easily prepared at low cost.

[0011] The advantage of this method is that it is possible to create a multi-level cushioning material for protecting goods of any shape from just one cellulosic foam, thus reducing the complexity of conversion and the amount of material used.

[0012] By providing at least one cut line that does not cut completely through the foam but only cuts to a certain depth in the solid cellulose foam, followed by compression by pressing the area defined by the at least one cut line, it is possible to produce a protective material that fits tightly around the shape of the item to be protected, regardless of the shape of the item. The cut line also provides a sharp, defined edge in the compressed area.

[0013] Another advantage of this method is that at least one compressed region remains fixed and integrated with one or more uncompressed regions of the formed cellulose foam, i.e., no cut-out material is wasted as in conventional methods.

[0014] Furthermore, the at least one compressed region has a higher density than the corresponding one or more uncompressed regions. A higher density correlates with a higher stiffness of the foam. Furthermore, the elasticity of the compressed regions is higher than that of the uncompressed regions. For example, during transportation and storage, it is important to hold in place within the foam any parts of the packaged goods that require additional protection, such as sharp edges and protruding parts, to avoid damage to both the packaged goods and the foam. Holding the packaged goods in place is facilitated by providing the foam with compressed regions of higher stiffness and elasticity.

[0015] However, compressing an area of ​​the material too much, or compressing the entire material, reduces the cushioning effect of the material as the foam deforms during compression. An advantage of the present invention is that the compression is regulated so that only certain areas are compressed (e.g., in the case of sharp edges) and other areas are not compressed or compressed to a lesser extent to ensure that the foam still has sufficient cushioning effect.

[0016] Yet another advantage is that the method is easy to implement in large scale setups.

[0017] Further aspects and embodiments are defined in the appended claims, which are specifically incorporated herein by reference.

[0018] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: The invention will now be explained in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0019] [Figure 1a] FIG. 1 is a top perspective view of a solid cellulose foam including cut lines defining a pattern. [Figure 1b] FIG. 1b shows the solid cellulose foam of FIG. 1a including compressed regions. [Figure 2] FIG. 1 is a side view of a solid cellulose foam containing two compressed regions of different depths and volumes. [Figure 3a] FIG. 1 is a top oblique view of half of a solid cellulose foam product including a compressed region. [Figure 3b] 3 shows a pressing tool for pressing a solid cellulose foam to form a compressed region of the solid cellulose foam product as shown in FIG. 3a. DETAILED DESCRIPTION OF THE INVENTION

[0020] Before the present invention is disclosed and described in detail, it is to be understood that the invention is not limited to the particular compounds, compositions, method steps, substrates, and materials disclosed herein, as such compounds, compositions, method steps, substrates, and materials may vary somewhat. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims and equivalents thereof.

[0021] It should be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0022] Unless otherwise defined, all terms and scientific terms used herein are intended to have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs.

[0023] Unless expressly indicated, all percentages are calculated by weight.

[0024] As used herein, the expression "cut line" refers to a cut made in a solid foam system material, said cut line indicating a depth within the material and only a partial through cut.

[0025] As used herein, the term "foam" refers to a material created by entrapping air or gas bubbles within a solid or liquid. Generally, the volume of gas is much greater than the volume of the liquid or solid, and a thin film separates the pores. To form a foam, three requirements must be met: Mechanical work is required to increase the surface area. This can occur by agitation, dispersion of a large amount of gas into the liquid, or injection of gas into the liquid. The second requirement is the presence of a blowing agent, typically an amphiphile, surfactant, or surface-active component, to reduce surface tension. Finally, the foam must form more quickly than it can break down.

[0026] The term "cellulose foam" as used herein refers to a foam containing cellulose and other components such as thickeners, surfactants, and additives. The main component of cellulose foam is cellulose, which constitutes at least 70% by weight of the dry content of the cellulose foam. The cellulose is in the form of fibers, and therefore the foam can also be defined as a fiber foam or a cellulose fiber foam. The cellulose foam can be wet or solid.

[0027] As used herein, the term "wet foam" or "wet cellulose foam" refers to a wet foam containing cellulose and other components such as thickeners, surfactants, and additives. Air bubbles exist within the wet foam. The wet foam is self-supporting and behaves as a viscoelastic solid, meaning that the wet foam has both viscous and elastic properties. The wet foam behaves as a solid and is therefore self-supporting unless a sufficiently large force is applied that the wet foam begins to flow and instead behaves as a viscous material. Depending on the magnitude and time scale of any applied shear stress, the wet foam can exhibit predominantly viscous or elastic behavior.

[0028] As used herein, the terms "solid cellulose foam" or "dried cellulose foam" refer to a dry porous cellulose material formed from wet cellulose foam, i.e., a foam-molding material. 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. The resulting solid cellulose foam has a shape that largely conforms to the shape of the wet cellulose foam. The dry content of the solid cellulose foam can be 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 retained even in an unconstrained state. The solid cellulose foam has an open-cell structure, allowing air to enter the pores within the foam. The solid cellulose foam can also be described as a porous or low-density material.

[0029] In a first aspect, the present invention provides a method for forming at least one compressed region in a solid cellulose foam. In a second aspect, the present invention relates to an article made from the solid cellulose foam.

[0030] The solid cellulose foam preferably comprises: a) 71 to 95% by weight of cellulose fibers, calculated based on the total weight of the solid content of the composition; b) 4 to 24% by weight of a water-soluble thickener, calculated based on the total weight of the solid content of the composition; c) at least two surfactants; The foam may be prepared from a foam composition comprising:

[0031] 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 may contain lignin or hemicellulose, or both, or the cellulose fibers may be free of lignin and hemicellulose. Preferably, the cellulose fibers are derived from wood, and more preferably, they are pulp fibers obtained by a pulping process that liberates fibers from the wood matrix. They can be liberated by mechanical pulping, such as thermomechanical pulping (TMP) or chemothermomechanical pulping (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 liberated by chemical pulping. The different characteristics of each cellulose fiber affect the properties of the final cellulose foam. Cellulose fibers are significantly longer than they are wide. 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 hardwoods can have fiber lengths of 0.7 to 1.6 mm, and eucalyptus can have fiber lengths of 0.7 to 1.5 mm. However, fiber lengths can vary considerably depending on the growing location. Cellulose fibers in the cellulose foams disclosed herein can have lengths of 0.1 mm to 65 mm, or 0.1 mm to 10 mm, or 0.5 mm to 65 mm, or 0.5 mm to 10 mm, or 0.5 mm to 7 mm. Fiber length can impart various mechanical characteristics to the foam. Due to the fiber length, the fibers can intertwine with each other, providing fiber-to-fiber interconnections that provide strength to the foam. The aspect ratio of the cellulose fibers in the cellulose foams according to the present invention, i.e., the ratio of fiber length to fiber width, can be at least 10, at least 25, at least 50, at least 75, or at least 100, which helps maintain and stabilize the foam structure during the drying process and allows the wet cellulose foam to dry while retaining its shape.The aspect ratio can be up to 6500, or preferably up to 2000.

[0032] The cellulose fibers may be modified to impart different properties to the final cellulose foam, for example, phosphated or periodate oxidized fibers may also be used when producing cellulose foams according to the present invention.

[0033] The cellulose fibers of the foam composition may be selected from wood pulp, regenerated cellulose fibers, and vegetable fibers such as fibers from bamboo, cotton, hemp, flax, and jute.

[0034] Preferably, the cellulose fibers are selected from wood pulp, such as softwood pulp, hardwood pulp, chemical thermomechanical pulp and dissolving pulp, or a combination of one or more of these.

[0035] More preferably, the cellulose pulp fibers are selected from softwood pulp, chemical thermomechanical pulp, or dissolving pulp.

[0036] Most preferably, the cellulose pulp fibers are selected from softwood pulps, such as softwood kraft bleached pulp.

[0037] The water-soluble thickener may be present in an amount of 4 to 24 wt. %, or 5 to 20 wt. %, calculated based on the total weight of the solids content of the foam. The 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, guar gum, and xyloglucan, or mixtures thereof.

[0038] The foam preferably comprises a mixture of at least two surfactants. One of the at least two surfactants is preferably a fast-acting surfactant, which quickly settles to the air-water interface during mechanical agitation during foam preparation, which helps to form a foam with high density and viscosity, thus enabling a self-supporting foam. A surfactant suitable for this purpose is an anionic surfactant, preferably a low-molecular-weight anionic surfactant. 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.

[0039] The other of at least two surfactants is preferably a co-surfactant.Co-surfactant may be selected from plant-derived raw materials, such as tetradecanoic acid (myristic acid), sodium oleate, lauric acid, palmitic acid and stearic acid, glucose-based co-surfactants with aliphatic carbon tails, such as alkylglycosides, alkylpolyglucosides, alkylthioglycosides and alkylmaltosides, amphoteric betaines, such as cocamidopropyl betaine (CAPB), sodium cocoiminodipropionate (CADP), polyethylene glycol sorbitan monolaurate, i.e., tween (for example, tween 20, tween 80 and tween 85), and high pKa fatty acids, such as polyoxyethylene lauryl ether, for example, polyethylene glycol dodecyl ether, pentaethylene glycol monododecyl ether and octaethylene glycol monododecyl ether.

[0040] The foam composition preferably comprises: a) disintegrating cellulose fibers in water to obtain a slurry of cellulose fibers; b) adding a thickener to the slurry obtained in a) to obtain a mixture of thickener and cellulose fibers in water; c) adding at least two surfactants to the mixture obtained in b) to obtain a fiber suspension; d) aerating the suspension obtained in c) to obtain a wet foam, the wet foam comprising 10-38% by weight of cellulose fibers, 0.5-10% by weight of a water-soluble thickener, and 0.1-2% by weight of a surfactant, calculated based on the total weight of the wet foam, and the wet foam has a viscosity of 140-500 kg / m 3 and a yield stress of 40 to 400 Pa; e) drying the wet foam obtained in d) to obtain a dry cellulose foam; It can be prepared by a method comprising:

[0041] The wet foam can be dried without the use of a mold, i.e., the wet foam is free-standing and retains its shape during drying without the need for a mold.

[0042] The wet foam is homogeneous and has good stability due to the small cell size (typically less than 100 μm) obtained when aerating a mixture of cellulose fibers, thickener, and surfactant. The wet foam does not aggregate during processing. The average cell size is largely maintained during any subsequent processing or drying steps, and the cellulose fibers remain well dispersed. The solid cellulose foam obtained by drying the wet foam is uniform in structure, strong, has good mechanical properties, a smooth surface, and is free of defects. In comparison, less stable wet cellulose foams have a large average cell size (i.e., typically greater than 100 μm), and the cells coalesce quickly during processing and drying, resulting in the formation of larger cells. Furthermore, the cellulose fibers form clusters during processing and drying, which causes the wet foam to collapse during drying. The resulting solid cellulose foam does not have a homogeneous structure and also contains defects in the morphology of the cavities caused by the coalesced cells in the wet foam. Due to these defects, such solid cellulose foams have a weak and rough surface.

[0043] The dried cellulose foam obtained in step e) can be used as a solid cellulose foam.

[0044] The dried cellulose foam obtained in step e) depositing discrete units of cellulose foam on a surface to obtain a first foam deposit; depositing wet cellulose foam between the discrete units to obtain a subsequent foam deposit; and drying the wet foam to obtain a solid foam having the discrete units of foam embedded in a foam matrix. The solid cellulose foam may then be used as a solid cellulose foam according to claim 1 and its dependent claims.

[0045] However, the solid cellulose foam may be prepared by other methods without departing from the scope of the present invention. For example, the solid cellulose foam may be prepared by depositing a wet foam in a single step into any desired shape. Optionally, any suitable confining means, such as a mold or frame, may be used.

[0046] The solid cellulose foam may be prepared, for example, by depositing the foam composition on a conventional papermaking machine for forming a foam web, or on a forming section of a papermaking machine suitably modified for that purpose.

[0047] Regardless of the method for preparing the solid cellulose foam, the solid cellulose foam preferably has a solids content in the range of 95 to 100 wt. %, or 98 to 100 wt. %, calculated based on the total weight of the foam.

[0048] The density of solid cellulose foam is 10 to 80 kg / m 3 , preferably 10 to 60 kg / m 3 , more preferably 20 to 50 kg / m 3 It could be.

[0049] The density of the solid cellulose foam may vary and therefore may be different at different locations. For example, when the cellulose foam composition is dried, the dried cellulose foam consists of a core with a uniform open-cell fiber network and a densified outer layer (i.e., upper surface, lower surface, and one or more side walls). The reason why the outer layer has a higher density is that the fibers are more densely packed and partially oriented in different directions within these layers. In this way, the densified outer layer is formed during drying and remains in the dried solid cellulose foam.

[0050] The densified outer layer has improved mechanical stability and strength compared to the core.

[0051] The solid cellulose foam preferably includes a densified outer layer that coincides with the top, bottom, and optionally one or more sidewalls of the foam. Solid cellulose foam is typically produced in large planks that are cut into smaller planks after drying. The large planks are typically thin, e.g., having a thickness in the range of 1-20 cm, or 1-10 cm, or 1-5 cm, or 4-6 cm, and the cutting is preferably performed so that the thickness remains the same after cutting. Thus, the densified outer layers on the top and bottom of the solid cellulose foam are preferably also present on the smaller planks, but the densified outer layers on the sidewalls may not be present.

[0052] In some embodiments, the densified outer layer is present only on the top surface.

[0053] The solid cellulose foam preferably comprises 71 to 95 wt. %, or more preferably 75 to 95 wt. %, of cellulose fibers calculated based on the total weight of the solids content of the foam.

[0054] The first aspect of the present invention, namely a method for forming at least one compressed region in a solid cellulose foam, is described in detail below with reference to the drawings.

[0055] The method for forming at least one compressed region in a solid cellulose foam comprises: a) providing a solid cellulose foam 1; b) providing at least one cutting line 2 of a predetermined cutting depth DC on at least one surface 11 of said solid cellulose foam 1, said at least one cutting line 2 defining at least one pattern 3 on said at least one surface 11; c) pressing at least one pressing tool 4 into said at least one pattern 3 on said at least one surface 11 of said cellulose foam 1, thereby forming at least one compressed area 12; Includes.

[0056] Step a—providing a solid cellulose foam—includes selecting a suitable solid cellulose foam 1. The selection of material properties, such as dimensions, foam composition, and density, should be made in relation to the article / goods to be packaged.

[0057] Preferably, the solid cellulose foam comprises: a) 71 to 95 wt. % cellulose fibers, calculated based on the total weight of the solid content of the solid foam; b) 4 to 24% by weight of a water-soluble thickener, calculated based on the total weight of the solid content of the solid foam; c) at least two surfactants; Includes.

[0058] The cellulose fibers are preferably selected from wood pulp, regenerated cellulose fibers, and vegetable fibers, preferably softwood pulp, such as softwood kraft bleached pulp, chemithermomechanical pulp (CTMP) and dissolving pulp, or any combination thereof.

[0059] The solid cellulose foam 1 can have a height H1, width W1, and length L1 that describe a three-dimensional (3D) shape.

[0060] The 3D shape may be a regular shape, such as a cube, diamond, or pyramid, or an irregular shape. The shape may be a cylinder having a height and a diameter.

[0061] The height H1 of the solid cellulose foam may be very small relative to the length L1 and the width W1, and the three-dimensional shape has that of a paperboard or plank (see Figures 1a and 1b).

[0062] The solid cellulose foam may be further described as comprising an upper surface 110, a lower surface 14, and at least one wall 13. In the embodiment shown in Figures 1a and 1b, the upper surface 110 and the at least one surface 11 defined in step b are coincident.

[0063] In embodiments in which the solid cellulose foam includes a densified outer layer, it will be appreciated that the densified outer layer corresponds to the upper surface 110, the lower surface 14, and optionally the at least one sidewall 13.

[0064] The article / goods to be packaged and protected in the formed solid foam may be, for example, a flat item (low height relative to length and width), or a three-dimensional item having a regular shape (e.g., a bottle), or an irregular shape (e.g., art glass).

[0065] After step a) has been carried out, ie after providing the solid cellulose foam 1, step b) is carried out.

[0066] Step b) comprises providing at least one cutting line 2 of a predetermined cutting depth DC on at least one surface 11 of said solid cellulose foam 1, whereby said at least one cutting line 2 defines at least one pattern 3 on said at least one surface 11.

[0067] Preferably, at least one surface 11 includes a densifying layer, which improves the strength of the surface.

[0068] The solid cellulose foam 1 has a thickness which may be variable or constant. In the area where at least one cutting line (2) is provided, the cellulose foam 1 has a thickness X, which is in the range of 2 to 20 cm, preferably 2 to 10 cm, and most preferably 4 to 6 cm.

[0069] A cutting tool (not shown), such as a knife or cutting blade or any other type of related sharp cutting tool, is preferably placed at a starting position near at least one surface 11 to be cut.

[0070] After positioning the cutting tool in a suitable starting position, the cutting tool is moved in a direction towards at least one surface 11 of said solid foam 1. This movement brings the cutting tool into direct contact with said at least one surface 11, and movement of the cutting tool is continued such that the cutting tool cuts into and penetrates one or more surfaces 11 and begins to cut into the solid foam 1.

[0071] The at least one cutting line 2 is positioned to cut partially through the thickness X of the solid cellulose foam (in some embodiments, the thickness X corresponds to a height H1, see FIG. 1a) to a predetermined cutting depth DC, such that the predetermined cutting depth DC is smaller than the thickness X of the cellulose foam 1.

[0072] Movement of the cutting tool (and cutting action) within the solid cellulose foam 1 continues until the predetermined cut depth DC into the solid foam 1 is reached. The cutting tool is then removed from the solid foam 1, leaving a cut line 2 in the solid cellulose foam 1. In Figure 1a, the cut line 2 is shown as a dashed line passing through the at least one surface 11, which in Figure 1a is the top surface 110, long side 16, and short side 17.

[0073] The predetermined cutting depth DC of the at least one cutting line 2 is preferably 90% or less of the thickness X of the cellulose foam 1, more preferably 70% or less, and most preferably 60% or less.

[0074] The cutting line 2 is preferably provided so that the cutting depth DC is perpendicular to the surface 11 on which the cutting line 2 is provided.

[0075] In some embodiments, the cutting tool comprises two or more knives or blades. When using a cutting tool with two or more knives or blades, two or more patterns can be cut in one and the same cutting action, i.e., in one step. It is further conceivable that the two or more knives or blades perform cutting lines with different cutting depths DC.

[0076] It is also conceivable to use a cutting tool with only one knife or blade, or to use two or more cutting tools with variable shapes and cutting depths DC, and to repeat step b) for all cutting tools.

[0077] The repetition of step b) of providing at least one cutting line 2 may be carried out before the pressing step c) or may be alternated with the pressing step c).

[0078] In some embodiments, the cutting tool may, in its simplest form, have a linear shape providing a linear cutting portion 21 .

[0079] In other embodiments, the cutting tool may be more complex in shape and may provide curved cuts 22 and / or cuts formed as closed loops 23 .

[0080] The at least one cutting line 2 disposed on at least one surface 11 of the cellulose foam 1 forms at least one pattern 3 on the at least one surface 11 of the solid cellulose foam.

[0081] The at least one pattern 3 may be formed as a closed loop defining a surface 30 having an area. The loop may have any shape, including angles and / or curves, for example rectangular, circular, square, oval, irregular, etc.

[0082] In some embodiments, the surface 30 may be defined by one or more linear cutting lines 2, or by a combination of linear and curvilinear cutting lines.

[0083] In another embodiment, the surface 30 of the at least one pattern is defined by at least one cutting line 2 and at least one edge E of the cellulose foam 1 (see Figures 1a-1b).

[0084] In a further embodiment, the surface 30 of the at least one pattern may be defined by at least one straight cutting line and at least one curved cutting line.

[0085] Step b) of the method is followed by a pressing step c).

[0086] Step c) comprises pressing at least one pressing tool 4 (an example of a pressing tool is shown in FIG. 3b) against the surface 30 of the at least one pattern 3 of the at least one surface 11 of the cellulose foam 1, thereby forming at least one compressed region 12.

[0087] After pressing, the entire surface 30 delimited by the pattern 3 forms the compressed region 12. This means that the entire surface 30 delimited by the pattern 3 is compressed. In some embodiments, the entire compressed region 12 is compressed to the same degree. Alternatively, the degree of compression varies within the compressed region 12. At least one cut line 2 forms the pattern 3, and thus the cut line defines the edge of the compressed region 12. The cut line that forms the edge of the compressed region 12 provides a sharp, well-defined edge.

[0088] Alternatively, if the cellulose foam 1 is pressed without first providing at least one cut line 2, the compressed region 12 will not have sharp, well-defined edges. For example, the edges of the compressed region 12 of the cellulose foam 1 may crack during pressing with the pressing tool 4, resulting in uneven edges.

[0089] The pressing step c) preferably begins with positioning the at least one pressing tool 4 at a starting position near the at least one pattern 3, and then moving the at least one pressing tool 4 towards the pattern 3 of the at least one surface 11, whereby the at least one pressing tool 4 contacts the surface 30 of the pattern 3 and applies pressure to the surface 30 of the pattern 3, thereby compressing the material 1.

[0090] The pressure applied by the at least one pressing area 40 of the at least one pressing tool 4 causes the at least one pattern 3 to be compressed in a direction consistent with the direction of the pressure and further compressed into the core of the solid cellulose foam 1.

[0091] The pressing tool 4 is removed after the pressing reaches a predetermined compression depth 43 .

[0092] 1a and 1b, at least one compression 12 is shown to be applied in a direction from the upper surface 110 towards the lower surface 14, parallel or approximately parallel to the height H1.

[0093] After said at least one pressing step is completed, at least one compressed region 12 is formed in the solid cellulose foam 1 .

[0094] The at least one pressing tool 4 may preferably have at least one pressing area 40 which corresponds to or is smaller than the area / surface 30 of the at least one pattern 3 of the at least one surface 11. Preferably, the pressing tool 4 has a pressing area 40 which corresponds to the surface 30 of the at least one pattern 3 of the at least one surface 11.

[0095] In some embodiments, the at least one pressed area 40 may include an edge line 41 surrounding the at least one pressed area 40, and the pressed edge line 41 may preferably be positioned to coincide with the at least one cutting line 2 during the pressing process.

[0096] The edge line 41 may preferably be a right-angled edge line 41 .

[0097] For more complex shaped articles, the at least one pressing tool 4 may have multiple pressing areas 40 (see Figure 3a), which in Figure 3a includes pressing areas 40A, 40B of different sizes.

[0098] Each pressed area 40A, 40B may have a respective pressed edge line 41A, 41B that forms a right angle in some embodiments.

[0099] However, embodiments are contemplated in which at least one of the pressure areas 40A, 40B may have a curved edge line.

[0100] The differently sized pressing areas 40A, 40B may also be differently shaped and arranged to compress to different pressing depths through the at least one surface 11. The thicknesses of the pressing tool 4 corresponding to the different pressing depths D1, D2 are shown in Figures 3a and 3b and are similarly designated.

[0101] In some embodiments, the pressing direction may be performed at an angle relative to the height H. In these embodiments, it may be preferred that at least one cutting line 2 also has the same angle relative to the height as the pressing direction. Preferably, the pressing direction is perpendicular or nearly perpendicular to at least one surface 11 to be compressed.

[0102] In some embodiments of the invention, steps b) and c) are performed simultaneously. The cutting tool and the pressing tool are one and the same tool, i.e. a combined tool that performs both cutting and pressing operations.

[0103] The composite tool preferably comprises at least one sharp edge for effecting the cutting and at least one pressing area for effecting the compression of the foam 1 .

[0104] In embodiments in which the composite tool is used and steps b and c are performed simultaneously as a composite process, it is contemplated that the composite process may be repeated two or more times rather than being performed only once.

[0105] Whether cutting and pressing are performed as separate steps or as a combined step, the solid cellulose foam 1 now comprises at least one compressed region 12 and at least one uncompressed region 10 .

[0106] The at least one compressed region 12 comprises a compressed solid cellulose foam 15 having a compressed thickness CMT (best seen in FIG. 1b) and a specific volume of voids V.

[0107] In some embodiments, the pressing step is carried out until a pressing depth equal to a predetermined cut depth DC is reached (see FIG. 1b). In these embodiments, the compressed thickness CTM can be calculated as the thickness X of the cellulose foam 1 at the location of at least one cut line 2 minus the predetermined cut depth DC of the cut line 2. CTM=X-DC

[0108] In other embodiments, the compression depth PD may be less than or greater than the predetermined cut depth DC. Preferably, the compression depth PD is equal to or less than the predetermined cut depth DC to ensure that the edges of the compressed region 12 are sharp and well-defined.

[0109] The solid cellulose foam 1 provided in step a) preferably has a uniform bulk density and preferably also has at least one densified layer. By pressing the at least one pressing tool 4 into the at least one pattern 3 of the foam 1, the density of the compressed solid cellulose foam 15 contained in the at least one compressed region 12 becomes higher than the density of the provided—and uncompressed—solid cellulose foam 1.

[0110] Preferably, the at least one cutting line 2 is provided on the surface 11 of the foam 1 which comprises a densified layer. Thus, the foam in the compressed zone 12 preferably also comprises a densified layer.

[0111] The density of the at least one compressed region 12 is preferably 10 to 90% higher than the density of the uncompressed region of the solid cellulose foam 1, more preferably 20 to 90%, most preferably 40 to 90% higher.

[0112] In some embodiments, the density of the compressed region 12 is 20-80% higher than the density of one or more uncompressed regions.

[0113] When solid cellulose foam is compressed, the density of the compressed region increases, as discussed above. This increases the stiffness and improves the resilience of the solid cellulose foam, which is important for keeping items in place, for example, during storage and transportation. Uncompressed solid cellulose foam has excellent cushioning properties due to the material's shock-absorbing properties. However, when compressed, the cushioning properties of solid cellulose foam begin to deteriorate as the open-cell structure of the foam deforms. If the degree of compression is high and the solid cellulose foam is compressed to less than about 30% of its original thickness, the cushioning properties can be significantly affected. Therefore, it is important to adjust the degree of compression depending on the merchandise or item to be protected.

[0114] Depending on the degree of compression and other conditions, such as relative humidity and compression time, solid cellulose foam may recover some or all of its original thickness when the pressing tool is removed. This is particularly true when the degree of compression is low, such that the solid cellulose foam is compressed to 90% or less of its original thickness. The greater the degree of compression, the greater the deformation that occurs to the foam, and the progressively less ability to recover its original thickness. In one embodiment, the optimal degree of compression is within the range of 10-90%, e.g., 20-80%, of its original thickness, resulting in no or only a small recovery of the original thickness after removal of the pressing tool. However, compressed foam has improved resilience compared to uncompressed foam. That is, compressed foam can significantly recover its compressed thickness, for example, upon impact. This is important when it comes to holding packaged items in place during impact.

[0115] As shown in FIG. 2, the formed solid cellulose foam 1 includes compressed regions 12A, 12B of different sizes having different depths 43A, 43B, which result in different volumes of the respective voids VA, VB.

[0116] The thicknesses of the compressed materials 15A, 15B in the compressed regions 12A, 12B may also vary and are designated as CMTA and CMTB, respectively.

[0117] The different thicknesses CMTA, CMTB correspond to different densities of the compressed materials 15A, 15B.

[0118] The at least one pressing tool 4 preferably has the same shape as at least a part of the article to be protected by the formed cellulose foam.

[0119] In some embodiments, the formed cellulose foam comprises two halves that are arranged to fit closely around the outside of the article to be protected. The halves may be identical or different.

[0120] The pressing step may be repeated one or more times to provide additional compressed regions 12 in the solid cellulose foam 1 .

[0121] In some embodiments, it may be preferable to use a second pressing tool having a pressing area of ​​a different size or shape than the area of ​​the first pressing tool, and to press said differently sized / shaped pressing tool into one or more already compressed areas.

[0122] In some embodiments, the at least one compressed region 12 extends to at least one edge E of the cellulose foam (FIGS. 1a-1b).

[0123] In some embodiments, the void V of the at least one compressed region 12 has the shape of a cavity, which may not be in direct contact with the edge E of the solid cellulose foam 1 (as shown in Figure 3a).

[0124] Embodiments are contemplated in which the solid cellulose foam 1 comprises different types of compressed regions 12 in different parts of the solid foam 1, such as void regions and compressed regions extending to at least one edge E of the foam 1. The shape, number and type of compressed regions are determined by the shape and design of the item to be protectively packaged.

[0125] Unlike pressing of thermoplastic foams, the pressing can preferably be carried out without the application of heat. Neither the at least one pressing tool nor the solid cellulose foam need to be heated. The lack of heat allows for a simple and energy-efficient pressing process.

[0126] In a second aspect, the present invention relates to an article made of solid cellulose foam, said article comprising at least one compressed region.

[0127] The compressed region 12 preferably has a density at least 10%, preferably 20-90%, more preferably 40-90% higher than the density of the uncompressed region(s). The density may be even higher, for example 50% or more higher.

[0128] In some embodiments, the density of the compressed region 12 is 20-80% higher than the density of one or more uncompressed regions.

[0129] The solid cellulose foam 1 preferably comprises a densified outer layer such that the upper surface 110, the lower surface 14, and optionally at least one sidewall 113 of the foam comprise the densified outer layer. Preferably, the surface 11, such as the upper surface 110, where the at least one cut line 2 is provided and where the at least one compressed region 12 is formed, comprises the densified outer layer.

[0130] The solid cellulose foam preferably comprises: a) 71 to 95% by weight of cellulose fibers calculated based on the total weight of the solid content of the foam; b) 4 to 24 wt. % of a water-soluble thickener calculated based on the total weight of the solid content of the foam; c) at least two surfactants; Includes.

[0131] The cellulose fibers of the product are selected from wood pulp, regenerated cellulose fibers, and vegetable fibers, preferably softwood pulp, such as softwood kraft bleached pulp, chemithermomechanical pulp (CTMP), and dissolving pulp, or combinations thereof.

[0132] In some embodiments, the product includes two or more sections arranged to be connected to one another to form a three-dimensional protective package containing at least one void V. The at least one void V, in these embodiments, may preferably be the sum of the respective voids of the two or more sections.

[0133] 3a shows a half of a product consisting of two identical halves, which when connected together have their respective voids V joining together to form a larger void, with the respective upper surfaces 110 of the halves being arranged to be fixed, e.g. glued, to one another after the article to be protected is placed on the first of the halves and the second half is placed with its upper surface 110 on the corresponding surface 110 of the first half.

[0134] The product of the present invention may preferably be used as a protective cover for the article or goods to be packaged. Fragile articles may particularly benefit from using the product defined by the claims, as the compressed areas may provide additional support to hold the article or goods in place, improving protection of the article, as they are held firmly in place by the compressed areas.

[0135] It is contemplated that the solid cellulose foam provided in step a) may be pre-compressed to some extent, for example to increase the density and therefore the strength of the solid cellulose foam, and that process step c) is carried out on the already compressed foam.

[0136] It is understood that in accordance with the methods and products of the present invention, it is undesirable to have through cut lines, i.e., cut lines having a cut depth equal to (or approximately equal to) the thickness X of the solid cellulose foam material 1, because this would prevent the pressing step c from being performed while maintaining the compressed regions 12 as fixed, integral parts of the solid foam. Rather, the compressed regions 12 are loosely fitting parts of the solid foam material 1 that risk coming loose and separating from the solid foam material, potentially subjecting the packaged item to impact and shock. [Example] [Example]

[0137] A 45 mm thick solid cellulose foam plank was pre-cut into shapes with a surface area of ​​76 × 76 mm and various depths (Table 1, "Cutting Depth"). The pre-cut pattern on the cellulose foam plank was then manually pressed using a 2 kg weight with a pressing area corresponding to the surface area of ​​the pre-cut pattern. The cellulose foam was dry and weighed 32-35 kg / m. 3 The fibers had a density ranging from 83 to 88% by weight of cellulose fibers (softwood bleached kraft pulp), 10 to 15% by weight of a thickener (CMC), and approximately 2% by weight of a surfactant (a mixture of myristic acid and sodium cocoyl sarcosinate). No heat was applied during pressing.

[0138] The weight was pressed to various depths (Table 1, "Depth at Applied Pressure") for various times. After pressing, the weight was removed. The thickness of the foam in the compressed area was measured 30 seconds (Table 1, "Depth at 30 seconds") and 24 hours (Table 1, "Depth at 24 hours") after pressure was removed.

[0139] The results are summarized in Table 1. All depths are measured as the height of the remaining foam measured from the bottom of the plank. TIFF2025532086000002.tif55170

[0140] The cellulose foam planks can be pressed to various depths and retain their shape after pressure is removed. Pre-cutting ensures sharp, defined edges on all pressed areas.

[0141] As will be appreciated by those skilled in the art, many variations and modifications can be made to these and other embodiments of the present invention without departing from the scope of the invention, which is defined in the appended claims.

[0142] It should be noted that the above aspect may be the subject of its own protection, such as in a separate divisional application. It is therefore foreseen that this aspect of the invention may require its own protection, for example, since it may be essentially applicable to other concepts different from those defined by the independent claims of the present application.

Claims

1. 1. A method for forming at least one compressed region in a solid cellulose foam, comprising: a. Providing a solid cellulose foam (1); b) providing at least one cutting line (2) of a predetermined cutting depth (DC) in at least one surface (11) of said solid cellulose foam (1), whereby said at least one cutting line (2) defines at least one pattern (3) on said at least one surface (11); c. pressing at least one pressing tool (4) into said at least one pattern (3) on said at least one surface (11) of said cellulose foam (1), thereby forming at least one compressed area (12); A method comprising:

2. 2. The method of claim 1, wherein the at least one cutting line (2) is arranged to cut partially through the thickness (X) of the cellulose foam (1) such that the predetermined cutting depth (DC) is smaller than the thickness (X) of the cellulose foam (1).

3. 3. The method according to claim 2, wherein the predetermined cutting depth (DC) of the at least one cutting line (2) is not more than 90%, preferably not more than 70%, more preferably not more than 60% of the thickness (X) of the cellulose foam.

4. 4. The method according to any one of claims 1 to 3, wherein the pressing step is carried out without heating the at least one pressing tool (4) and the cellulose foam (1).

5. 5. The method according to any one of claims 1 to 4, wherein the at least one pressing tool (4) has a pressing area (40) that corresponds to or is smaller than the area of ​​the at least one pattern (3) on the at least one surface (11).

6. The density of the uncompressed region (10) of the solid cellulose foam is 10 to 80 kg / m ３ , preferably 10 to 60 kg / m ３ , more preferably 20 to 50 kg / m ３ 6. The method according to claim 1, wherein the interval is:

7. 7. The method according to any one of claims 1 to 6, wherein the solid cellulose foam (1) comprises a densified outer layer.

8. 8. The method according to any one of claims 1 to 7, wherein the density of the at least one compressed zone (12) is higher than the density of the solid cellulose foam (1) provided in step a).

9. 9. The method according to any one of claims 1 to 8, wherein the density of the at least one compressed region (12) is preferably 10% to 90%, more preferably 20% to 90%, and most preferably 40% to 90% higher than the density of the uncompressed region (10) of the solid cellulose foam.

10. 10. The method according to any one of the preceding claims, wherein the at least one cutting line (2) defines a closed loop (23).

11. 11. The method according to any one of claims 1 to 10, wherein said at least one compression zone (12) has the shape of a cavity (C).

12. 11. The method according to any one of claims 1 to 10, wherein the at least one compressed area (12) extends to at least one edge (E) of the cellulose foam (1).

13. 13. The method according to any one of claims 1 to 12, wherein the at least one pressing tool (4) is pressed into the cellulose foam (1) to a pressing depth (PD) that is less than or equal to the predetermined cutting depth (DC) of the at least one cutting line.

14. The solid cellulose foam (1) a. 71 to 95 weight percent cellulose fibers, calculated based on the total weight of the solids content of the foam; b. 4 to 24 wt. % of a water-soluble thickener, calculated based on the total weight of the solids content of the foam; c. at least two surfactants; 14. The method of any one of claims 1 to 13, comprising:

15. 15. The method according to any one of claims 1 to 14, wherein the cellulose fibers are selected from wood pulp, regenerated cellulose fibers, and plant fibers, preferably softwood pulp, chemi-thermomechanical pulp (CTMP), and dissolving pulp, or a combination thereof.

16. 1. A product made of a solid cellulose foam (1), comprising at least one compressed region (12) having a density 10% to 90%, more preferably 20% to 90%, and most preferably 40% to 90% higher than the density of a non-compressed region (10) of said solid cellulose foam.

17. The solid cellulose foam (1) a. 71 to 95 weight percent cellulose fibers, calculated based on the total weight of the solids content of the foam material; b. 4 to 24% by weight of a water-soluble thickener, calculated based on the total weight of the solids content of the composition; c. at least two surfactants; 17. The article of manufacture of claim 16, comprising:

18. 18. The product of any one of claims 16 to 17, wherein the cellulose fibers are selected from wood pulp, regenerated cellulose fibers, and vegetable fibers, preferably selected from softwood pulp, chemi-thermomechanical pulp (CTMP), and dissolving pulp, or a combination thereof.

19. 19. The product of any one of claims 16 to 18, wherein the product comprises two or more parts arranged to be connected to each other to form a three-dimensional protective package comprising at least one void (V).

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