Method for forming solid cellulose foam

Abstract

The present invention relates to a method of forming at least one compressed zone in a solid cellulose foam, the method comprising the steps of: a) providing a solid cellulose foam; b) providing at least one cutting line having a predetermined cutting depth into at least one surface of the solid cellulose foam, whereby the at least one cutting line defines at least one pattern on the at least one surface; and c) pressing at least one pressing tool into the at least one pattern of the at least one surface of the cellulose foam, thereby forming at least one compressed zone. The invention further relates to a solid cellulose foam product formed by the process.

Description

Technical Field

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

[0002] The invention also relates to products obtained from the formed solid cellulose foam. Background Art

[0003] Virtually all consumer goods require protective packaging to cushion the goods during storage and transportation. It is recognized that there are many solutions for packaging and cushioning various goods, depending on the physical properties of the goods to be protected and the degree of protection required in connection with their application.

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

[0005] There are many challenges in finding foam materials from renewable resources. Many bio-based foams have higher production costs and lower mechanical properties, as well as poor stability in water or high temperatures compared to long-established foams from oil-based sources. Bio-based and recyclable protective materials need to have the same excellent properties and performance as petroleum-based protective materials to be preferred over petroleum-based materials.

[0006] The low weight and good impact absorption of bio-based foams are examples of crucial properties. Furthermore, the ability to tailor the shape and form of the bio-based foam to the shape and form of the goods to be protected by the protective material is extremely important. As the most abundant renewable natural polymer on earth, cellulose has been shown to have particular potential due to 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. WO20200011587A1 describes a porous material prepared by aerating a paste containing cellulose fibers and gluten and depositing the aerated paste in a mold where the paste is dried. WO2015036659A1 describes a molded cellulosic product prepared by foaming an aqueous suspension of natural fibers combined with synthetic fibers and a surfactant, feeding the cellulosic foam into a mold where the cellulosic foam is dried to produce a dry cellulosic product.

[0008] There remains a need for natural, bio-based and recyclable protection and cushioning materials, allowing the material to be fully recyclable in the normal paper and board stream and become part of the circular material stream in the existing packaging waste management system. The protection and cushioning materials need to be suitable for various conversion methods and designed for the complex shapes of the goods to be protected and allow for optimized cushioning and packaging dimensions. Summary of the invention

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

[0010] Thanks to the process according to claim 1, shaped solid cellulose foams suitable for protecting goods of any shape can be prepared easily and at low cost.

[0011] The advantage of adopting this method is that a multi-level cushioning material for protecting goods of any shape can be constructed from only one piece of cellulose foam, thereby reducing the complexity of conversion and the use of materials.

[0012] Providing at least one cutting line, which does not cut completely through the foam, but only to a certain cutting depth of the solid cellulose foam, and then compressing by pressing the area defined by the at least one cutting line, makes it possible to produce a protective material that provides a close fit around the shape of the goods to be protected, regardless of the shape of the goods. The cutting line also provides a sharp, well-defined edge for the compressed area.

[0013] Another advantage of using this method is that the at least one compressed region remains fixed to and integrated with the one or more uncompressed regions of the formed cellulose foam, ie there is no waste of cut-out material as occurs with conventional methods.

[0014] In addition, the at least one compressed area will have a higher density than the corresponding one or more uncompressed areas. Higher density is associated with a higher stiffness of the foam. In addition, the resilience of the compressed areas will be higher than the resilience of the uncompressed areas. During, for example, transportation and storage, it is important to keep any parts of the packaged goods that require additional protection (such as sharp edges and protruding parts) in place within the foam to avoid damage to both the packaged goods and the foam. By providing the foam with compressed areas with higher stiffness and resilience, it helps to keep the packaged goods in place.

[0015] However, compressing areas of material too much or compressing the entire material will reduce the cushioning effect of the material because the foam deforms during compression. An advantage of the present invention is that the compression is tailored so that only certain areas are compressed (e.g. for sharp edges) and other areas are not compressed, or are compressed only to a low degree, thereby ensuring that the foam still has sufficient cushioning effect.

[0016] Yet another advantage is that the process is easily carried out in large-scale equipment.

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

[0018] The foregoing aspects of the present invention and many of the attendant advantages will become more readily understood as the same becomes better appreciated by reference to the following detailed description when used in conjunction with the accompanying drawings, wherein:

[0019] The present invention will be described in more detail with reference to the accompanying drawings, in which:

[0020] Figure 1a shows an upper oblique side view of a solid cellulose foam including cut lines defining a pattern;

[0021] Figure 1b shows that the compressed area is now Figure 1a of said solid cellulose foam;

[0022] Figure 2 is a side view showing a solid cellulose foam comprising two compressed regions having different depths and volumes;

[0023] Figure 3a shows half of a solid cellulose foam product comprising a compression zone and viewed obliquely from above, and

[0024] Figure 3b A method for pressing a solid cellulose foam to form a Figure 3a A pressing tool in the compression zone of a solid cellulose foam product is shown in FIG. DETAILED DESCRIPTION

[0025] Before the present invention is disclosed and described in detail, it should be understood that the present invention is not limited to the specific compounds, configurations, method steps, substrates, and materials disclosed herein, because such compounds, configurations, method steps, substrates, and materials may vary slightly. It should also be understood that the terminology employed herein is only for the purpose of describing specific embodiments and is not intended to be limiting, because the scope of the present invention is limited only by the appended claims and their equivalents.

[0026] It must 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.

[0027] Unless otherwise defined, any 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.

[0028] Unless otherwise indicated, all percentages are by weight.

[0029] As used herein, the expression "cut line" denotes a cut made in a solid foam-based material. The cut line exhibits a certain depth in the material and is a cut that only partially penetrates.

[0030] As used herein, the term "foam" refers to a substance made by trapping air or gas bubbles inside a solid or liquid. Typically, the volume of the gas is much larger than the volume of the liquid or solid, with a thin film separating the gas pockets. In order to form a foam, three requirements must be met. Mechanical work is required to increase the surface area. This can occur by stirring, dispersing a large amount of gas into the liquid, or injecting the gas into the liquid. The second requirement is that a foam former (typically an amphiphilic substance), a surfactant, or a surface-active component must be present to reduce surface tension. Finally, the foam must form more quickly than the foam bursts.

[0031] As used herein, the term "cellulose foam" refers to a foam comprising cellulose and other components such as thickeners, surfactants and additives. The main component of the cellulose foam is cellulose, such that cellulose constitutes at least 70 wt % of the dry content of the cellulose foam. Cellulose has the form of fibers, and therefore, the foam may also be defined as a cellulosic foam or a cellulose fiber foam. The cellulose foam may be wet or solid.

[0032] As used herein, the term "wet foam" or "wet cellulose foam" refers to a wet foam comprising cellulose and other components such as thickeners, surfactants, and additives. Gas bubbles are present within the wet foam. The wet foam is free-standing and behaves as a viscoelastic solid. This means that the wet foam has both viscosity and elasticity. The wet foam will behave as a solid, and therefore free-standing, unless a force large enough is applied to cause it to begin to flow and behave instead as a viscous material. Depending on the magnitude and time scale of any applied shear stress, the wet foam may exhibit predominantly viscous or elastic behavior.

[0033] As used herein, the term "solid cellulose foam" or "dried cellulose foam" refers to a dry porous cellulose material that has been formed from a wet cellulose foam (i.e., a foam-forming material). During the drying process, the closed-cell wet cellulose foam is converted into an open-cell solid cellulose foam. During the drying process, the network of cellulose fibers is prevented from collapsing. Therefore, the solid cellulose foam will have a shape that corresponds to the shape of the wet cellulose foam to a large extent. The dry content of the solid cellulose foam may be at least 95 wt%, calculated based on the total weight of the solid cellulose foam. The shape and density of the solid cellulose foam are also maintained in an unrestricted state. The solid cellulose foam has an open-cell structure that allows air to occupy the pores within the foam. The solid cellulose foam may also be described as a porous material or a low-density material.

[0034] In a first aspect, the present invention provides a method of forming at least one compressed region in a solid cellulose foam. In a second aspect, the present invention relates to a product made from the solid cellulose foam.

[0035] The solid cellulose foam may preferably be prepared from a foam composition comprising:

[0036] a) 71-95 wt% of cellulose fibers, calculated on the total weight of the solid content of the composition,

[0037] b) 4 to 24 wt% of a water-soluble thickener, calculated on the total weight of the solid content of the composition, and

[0038] c) at least two surfactants.

[0039] Cellulosic fibers suitable for use in the present invention may be derived from wood (e.g., softwood or hardwood), from leaves, or from fiber crops (including cotton, flax, and hemp). Cellulosic fibers suitable for use in the present invention may also be derived from regenerated cellulose, such as rayon and Lyocell. Cellulosic fibers suitable for use in the present invention may include 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, the cellulose fibers are pulp fibers obtained by a pulping process in which the fibers are released from a wood matrix. The pulp fibers may be released as follows: by mechanical pulping to obtain mechanical pulp, such as thermomechanical pulp (TMP) or chemical thermomechanical pulp (CTMP); or, by chemical pulping, such as kraft pulp or pulp obtained by sulfite process, soda process, or organic solvent pulping process. More preferably, the cellulose fibers are pulp fibers released by a chemical pulping process. The different characteristics of each cellulose fiber will affect the properties of the final cellulose foam. Compared to the width of the cellulose fibers, it is significantly longer. The cellulose fibers may have an average width of 0.01-0.05 mm. The fiber length of softwood can be 2.5-4.5mm, while hardwood can have a fiber length of 0.7-1.6mm, and eucalyptus is 0.7-1.5mm. However, the fiber length can vary considerably with different growing locations, etc. The cellulose fibers in the cellulose foam disclosed herein can have a length of 0.1mm-65mm, or 0.1mm-10mm, or 0.5mm-65mm, or 0.5mm-10mm, or 0.5mm-7mm. The fiber length can provide different mechanical properties for the foam. Due to the length of the fibers, they can entangle with each other and give the mutual combination of fibers to fibers (which brings strength to 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 can be at least 10, at least 25, at least 50, at least 75, or at least 100, which provides the retention and stability of the foam structure during the drying procedure, making it possible to dry the wet cellulose foam in a retained shape. The aspect ratio can be up to 6500, or preferably up to 2000.

[0040] The cellulose fibers may be modified to provide different properties to the final cellulose foam. For example, phosphorylated fibers or periodate-oxidized fibers may also be used when producing cellulose foams according to the present invention.

[0041] The cellulosic fibers of the foam composition may be selected from: wood pulp; regenerated cellulose fibers; and plant fibers, such as fibers from bamboo, cotton, hemp, flax, and jute.

[0042] Preferably, the cellulosic fibers are selected from: wood pulp, such as softwood pulp, hardwood pulp, chemithermomechanical pulp; and dissolving pulp; or a combination of one or more of these.

[0043] More preferably, the cellulosic pulp fibers are selected from softwood pulp, chemithermomechanical pulp, or dissolving pulp.

[0044] Most preferably, the cellulosic pulp fibers are selected from softwood pulps, such as softwood kraft bleached pulp.

[0045] The water-soluble thickener can be present in an amount of 4-24wt% or 5-20wt%, calculated by the total weight of the solid content of the foam. The thickener can have a molecular weight of 80000-250000g / mol or 83000-197000g / 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.

[0046] The foam preferably comprises a mixture of at least two surfactants. One of the at least two surfactants is preferably a fast-acting surfactant that settles rapidly at the air-water interface during mechanical stirring during the preparation of the foam, which helps to form a foam with high density and high viscosity and is therefore able to become a self-standing foam. Suitable surfactants for this purpose are anionic surfactants, preferably low molecular weight anionic surfactants. Low molecular weight anionic surfactants can be selected from: sodium dodecyl sulfate (SDS); potassium dodecyl sulfate, sodium laureth sulfate (SLES); sodium dodecylbenzene sulfonate; sodium cocoyl sarcosinate; sodium lauroyl sarcosinate. Low molecular weight anionic surfactants are preferably selected from: sodium dodecyl sulfate (SDS); sodium p-n-dodecylbenzene sulfonate; 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.

[0047] The other of the at least two surfactants is preferably a cosurfactant. The cosurfactant may be selected from: high pKa fatty acids, such as raw materials of plant origin, such as myristic acid, sodium oleate, lauric acid, palmitic acid, and stearic acid; glucose-based cosurfactants with aliphatic carbon tails, such as alkyl glycosides, alkyl polyglucosides, alkyl thioglycosides, and alkyl maltosides; amphoteric betaines, such as cocamidopropyl betaine (CAPB), and sodium cocoimidodipropionate (CADP); polyethylene glycol sorbitan monolaurate, i.e. (For example 20. 80 and 85); and polyoxyethylene lauryl ethers, such as polyethylene glycol lauryl ether, pentaethylene glycol monododecyl ether and octaethylene glycol monododecyl ether.

[0048] The foam composition can preferably be prepared by a method comprising the following steps:

[0049] a) decomposing cellulose fibers in water to obtain a slurry of cellulose fibers;

[0050] b) adding a thickener to the slurry obtained in a) to obtain a mixture of thickener and cellulose fibers in water;

[0051] c) adding the at least two surfactants to the mixture obtained in b) to obtain a fiber suspension;

[0052] d) aerating the suspension obtained in c) to obtain a wet foam,

[0053] The wet foam comprises 10-38 wt% of cellulose fibers, 0.5-10 wt% of a water-soluble thickener, and 0.1-2 wt% of a surfactant, calculated based on the total weight of the wet foam, and the wet foam has a density of 140-500 kg / m 3 Density and yield stress of 40-400Pa;

[0054] e) drying the wet foam obtained in d) to obtain a dry cellulose foam.

[0055] The wet foam can be dried without the use of a mold, ie, the wet foam is free-standing and retains its shape during drying without the need for a mold.

[0056] Due to the small bubble size (typically below 100 μm) obtained when the mixture of cellulose fibers, thickeners and surfactants is aerated, the wet foam is homogeneous and has good stability. The wet foam does not flocculate during processing. During any subsequent processing or drying steps, the average bubble size remains unchanged to a large extent, and the cellulose fibers remain well dispersed. The resulting solid cellulose foam obtained by drying the wet foam will be uniform, firm, have good mechanical properties, smooth surface and no defects in structure. In contrast, the wet cellulose foam with low stability has a larger average bubble size (i.e., typically above 100 μm), and the bubbles will merge faster during processing and drying, so that larger bubbles are formed. In addition, the cellulose fibers will form clusters during processing and drying. This causes the wet foam to collapse during drying. The resulting solid cellulose foam will not have a uniform structure and will also contain defects in the form of cavities generated by the merged bubbles in the wet foam. Due to the defects, such solid cellulose foam is not firm and has a rough surface.

[0057] The dried cellulose foam obtained in step e) can be used as solid cellulose foam.

[0058] The dried cellulose foam obtained in step e) may be obtained by a process comprising:

[0059] depositing discrete cells of cellulose foam on a surface to obtain a first foam deposition,

[0060] depositing wet cellulose foam between said discrete cells to obtain subsequent foam deposition, and,

[0061] The wet foam is dried to obtain a solid foam wherein discrete cells of foam are embedded in a foam matrix. The solid cellulose foam can then be used as the solid cellulose foam of claim 1 and its dependent claims.

[0062] However, without departing from the scope of the present invention, the solid cellulose foam may be prepared by other methods than those described above. For example, the solid cellulose foam may be prepared by a single deposition of wet foam into any desired shape. Optionally, any suitable confinement means may be used, such as a mold or a frame.

[0063] The solid cellulose foam can be prepared, for example, by depositing the foam composition on the forming section of a conventional papermaking machine for forming foam webs or on a papermaking machine suitably adapted for this purpose.

[0064] Regardless of the method of preparation of the solid cellulose foam, the solid cellulose foam preferably has a solids content in the range of 95-100 wt%, or 98-100 wt%, calculated on the total weight of the foam.

[0065] The density of solid cellulose foam can be 10-80kg / m 3 , preferably 10-60kg / m 3 , and more preferably 20-50kg / m 3 .

[0066] The density of the solid cellulose foam may vary and therefore be different at different locations. For example, when the cellulose foam composition is dried, the dried cellulose foam will consist of a core comprising a uniform open-cell fiber network and a densified outer layer (i.e., an upper surface, a lower surface, and one or more side walls). The density of the outer layer is higher because the fibers are more densely packed and partially oriented differently in these layers. The densified outer layer is thus formed during the drying process and will also remain in the dried solid cellulose foam.

[0067] The densified outer layer has improved mechanical stability and strength compared to the core.

[0068] The solid cellulose foam preferably comprises the densified outer layer conforming to the upper surface, the lower surface and optionally one or more side walls of the foam. Solid cellulose foam is usually produced in the form of large boards, which are cut into smaller boards after drying. The large boards are typically thin, for example having a thickness in the range of 1-20 cm, or 1-10 cm, or 1-5 cm, or 4-6 cm, and are preferably cut so that the thickness remains the same after cutting. The densified outer layer located on the upper and lower surfaces of the solid cellulose foam is thus preferably also present on the smaller boards, while the densified outer layer located on the side walls may not be present.

[0069] In some embodiments, the densified outer layer is present only on the upper surface.

[0070] The solid cellulose foam preferably comprises 71-95 wt%, or more preferably 75-95 wt%, cellulose fibres, calculated on the total weight of the solid content of the foam.

[0071] A first aspect of the present invention, namely a method of forming at least one compressed region in a solid cellulose foam, will now be described in detail hereinafter and with reference to the accompanying drawings.

[0072] The method of forming at least one compressed region in a solid cellulose foam comprises the following steps:

[0073] a) providing a solid cellulose foam 1;

[0074] b) providing at least one cutting line 2 having a predetermined cutting depth DC into 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; and

[0075] c) pressing at least one pressing tool 4 into said at least one pattern 3 of said at least one surface 11 of said cellulose foam 1 , thereby forming at least one compressed area 12 .

[0076] Said step a (providing a solid cellulose foam) comprises selecting a suitable solid cellulose foam 1. The choice of eg size, composition and material properties (eg density) of the foam is made in relation to the article / goods to be packaged.

[0077] Preferably, the solid cellulose foam comprises:

[0078] a) 71-95 wt% cellulose fibers, calculated based on the total weight of the solid content of the solid foam;

[0079] b) 4 to 24 wt% of a water-soluble thickener, calculated on the total weight of the solid content of the solid foam, and

[0080] c) at least two surfactants.

[0081] The cellulose fibers are preferably selected from wood pulp, regenerated cellulose fibers, and plant fibers; preferably selected from softwood pulp (eg softwood kraft bleached pulp), chemithermomechanical pulp (CTMP) and dissolving pulp or any combination thereof.

[0082] The solid cellulose foam 1 may have a height H1 , a width W1 and a length L1 describing a three-dimensional (3D) shape.

[0083] The 3D shape may be a regular shape (eg, a cube, a diamond, or a pyramid) or an irregular shape. The shape may be a cylinder having a height and a diameter.

[0084] The height H1 of the solid cellulose foam can be so small relative to the length L1 and the width W1 that the three-dimensional shape has the shape of a sheet or board, see Figure 1a and 1b .

[0085] The solid cellulose foam can be further described as comprising an upper surface 110, a lower surface 14, and at least one wall 13. Figure 1a and 1b In the embodiment shown in , the upper surface 110 corresponds to the at least one surface 11d defined in step b.

[0086] It should be understood that for embodiments wherein the solid cellulose foam comprises a densified outer layer, the densified outer layer corresponds to the upper surface 110 , the lower surface 14 and optionally the at least one side wall 13 .

[0087] The articles / goods to be packaged in and protected by the formed solid foam may be, for example, flat goods items (small height relative to length and width) or three-dimensional goods items having a regular shape (such as a bottle) or having an irregular shape (such as a piece of art glass).

[0088] After step a) (ie providing a solid cellulose foam 1) has been carried out, step b) is carried out.

[0089] Step b) comprises providing at least one cutting line 2 having a predetermined cutting depth DC into 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 .

[0090] Preferably, said at least one surface 11 comprises a densified layer. The densified layer provides improved strength to the surface.

[0091] The solid cellulose foam 1 has a variable or constant thickness. At the location where the at least one cutting line (2) is to be provided, the cellulose foam 1 has a thickness X; the thickness X is in the interval of 2-20 cm, preferably 2-10 cm, and most preferably 4-6 cm.

[0092] A cutting tool (not shown), such as a knife or a cutting blade or some other type of related and sharp-edged cutting tool, is preferably arranged at a starting position adjacent to the at least one surface 11 intended to be cut into.

[0093] After the cutting tool has been positioned in a suitable starting position, the cutting tool is moved in a direction towards at least one surface 11 of the solid foam 1. This movement brings the cutting tool into direct contact with the at least one surface 11, and the movement of the cutting tool continues so that the cutting tool begins to cut into and through one or more surfaces 11 and into the solid foam 1.

[0094] The at least one cutting line 2 is arranged to partially cut through the thickness X of the solid cellulose foam (in some embodiments, the thickness X coincides with the height H1, see Figure 1a ) to a predetermined cutting depth DC, so that the predetermined cutting depth DC is less than the thickness X of the cellulose foam 1.

[0095] The movement of the cutting tool in the solid cellulose foam 1 (and the cutting operation) continues until the predetermined cutting depth DC into the solid foam 1 is reached. Then, the cutting tool is removed from the solid foam 1, leaving a cutting line 2 in the solid cellulose foam 1. Figure 1a In FIG. 1 , the cutting line 2 is shown as a dotted line extending on the at least one surface 11, wherein the at least one surface 11 is Figure 1a In the middle are the upper surface 110 , the long side surfaces 16 , and the short side surfaces 17 .

[0096] The predetermined cutting depth DC of the at least one cutting line 2 is preferably 90% or less, more preferably 70% or less, and most preferably 60% or less of the thickness X of the cellulose foam 1 .

[0097] Preferably, the cutting line 2 is provided such that the cutting depth DC is perpendicular to the surface 11 on which the cutting line 2 is provided.

[0098] 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 at once in the same cutting operation (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.

[0099] It is also conceivable to use a cutting tool having only one knife or blade and to use two or more cutting tools with variable shapes and cutting depths DC and to repeat step b) for each cutting tool.

[0100] The repetition of step b) (providing at least one cutting line 2) can be carried out before step c) (pressing step) or can be carried out alternately with the pressing step c).

[0101] In some embodiments, the cutting tool may, in its simplest form, have a linear shape providing a linear cut 21 .

[0102] In other embodiments, the cutting tool may have a more complex shape and provide a curved cut 22 and / or a cut formed as a closed loop 23 .

[0103] The at least one cutting line 2 arranged on at least one surface 11 of the cellulose foam 1 defines at least one pattern 3 on the at least one surface 11 of the solid cellulose foam.

[0104] 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 and may contain corners and / or curves, such as rectangular, circular, square, oval, irregular, etc.

[0105] In some embodiments, the surface 30 may be defined by one or more linear cutting lines 2 or by a combination of linear cutting lines and curved cutting lines.

[0106] In other embodiments, 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 Figure 1a -b).

[0107] In further embodiments, the surface 30 of the at least one pattern may be defined by at least one linear cut line and at least one curved cut line.

[0108] Step b) of the process is followed by a pressing step (step c)).

[0109] Step c) comprises placing at least one pressing tool 4 (an example of a pressing tool is shown in Figure 3b ) is pressed into 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 area 12.

[0110] After pressing, the entire surface 30 defined by the pattern 3 forms a compressed area 12. This means that the entire surface 30 defined by the pattern 3 has been compressed. In some embodiments, the entire compressed area 12 has been compressed to the same extent. Alternatively, the degree of compression varies within the compressed area 12. The at least one cutting line 2 defines the pattern 3, and the one or more cutting lines will thus form the edge of the compressed area 12. By the one or more cutting lines forming the edge of the compressed area 12, a sharp and well-defined edge is provided.

[0111] If the cellulose foam 1 is pressed without first providing at least one cutting line 2, the compressed area 12 will not have sharp and clearly defined edges. For example, the edge of the compressed area 12 of the cellulose foam 1 may break during the pressing process with the pressing tool 4, so that the edge becomes uneven.

[0112] The pressing step c) preferably starts with positioning the at least one pressing tool 4 to a starting position adjacent to the at least one pattern 3, and then moving the at least one pressing tool 4 toward the pattern 3 of the at least one surface 11, so that the at least one pressing tool 4 contacts the surface 30 of the pattern 3 and applies pressure on the surface 30 of the pattern 3, thereby compressing the material 1.

[0113] Said pressure applied by said at least one pressing area 40 of said at least one pressing tool 4 causes said at least one pattern 3 to be compressed in a direction coinciding with the direction of said pressing and further into the core of the solid cellulose foam 1 .

[0114] After a predetermined compression depth 43 has been reached by the pressing, the pressing tool 4 is removed.

[0115] exist Figure 1a and 1b In FIG. 1 , it is shown that the at least one compression 12 has been performed in a direction from the upper surface 110 towards the lower surface 14 and parallel or almost parallel to the height H1 .

[0116] After the at least one pressing step has been completed, at least one compressed zone 12 has been formed in the solid cellulose foam 1 .

[0117] 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.

[0118] In some embodiments, the at least one pressed area 40 may comprise an edge line 41 surrounding the at least one pressed area 40 , and the pressed edge line 41 may preferably be arranged to coincide with the at least one cutting line 2 during the pressing step.

[0119] The edge line 41 may preferably be a right-angle edge line 41 .

[0120] For articles of more complex shapes, the at least one pressing tool 4 may have more than one pressing area 40 (see Figure 3a ).exist Figure 3a In the embodiment, the pressing area 40 includes pressing areas 40A and 40B of different sizes.

[0121] In some embodiments, each pressed region 40A, 40B may have a respective pressed edge line 41A, 41B at a right angle.

[0122] However, embodiments are conceivable in which at least one of the pressed regions 40A, 40B may have a curved edge line.

[0123] The pressing areas 40A, 40B of different sizes may also have different shapes and be arranged to penetrate and compress the at least one surface 11 to different pressing depths. The thickness of the pressing tool 4 corresponding to the different pressing depths D1, D2 is Figure 3a and 3b Shown in and named similarly.

[0124] In some embodiments, the pressing direction may be performed at an angle to the height H. In these embodiments, it may be preferred that the 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 almost perpendicular to the at least one surface 11 to be compressed.

[0125] In some embodiments of the present invention, step b) and step c) are performed simultaneously, and the cutting tool and the pressing tool are the same tool, ie, a combined tool that performs both cutting and pressing operations.

[0126] Said combined tool preferably comprises at least one sharp edge for providing said cutting and at least one pressing area for carrying out the compression of the foam 1 .

[0127] In the embodiment in which the combined tool is used and step b and step c are performed simultaneously in the combined step, it is conceivable to perform the combined step not only once but to repeat the combined step two or more times.

[0128] Regardless of 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 .

[0129] The at least one compressed zone 12 comprises a compressed solid cellulose foam 15 having a compressed thickness CMT (in Figure 1b best seen in Figure 2) and a void V of a specific volume.

[0130] In some embodiments, the pressing step is performed until a pressing depth equal to a predetermined cutting depth DC is reached, see Figure 1b For these embodiments, the compressed thickness CTM may be calculated as the thickness X of the cellulose foam 1 at the location of the at least one cutting line 2 minus the predetermined cutting depth DC of the cutting line 2:

[0131] CTM=X-DC

[0132] In other embodiments, the pressing depth PD may be less than or greater than the predetermined cutting depth DC. Preferably, the pressing depth PD is less than or equal to the predetermined cutting depth DC to ensure that the edge of the compressed area 12 is sharp and has a clear boundary.

[0133] The solid cellulose foam 1 provided in step a) preferably has a uniform bulk density and preferably also has at least one densified layer. Pressing the at least one pressing tool 4 into the at least one pattern 3 of the foam 1 results in the compressed solid cellulose foam 15 contained in the at least one compressed area 12 having a higher density than the provided and uncompressed solid cellulose foam 1.

[0134] Preferably, the at least one cutting line 2 is provided in the surface 11 of the foam 1 comprising a densification layer. The foam in the compression zone 12 thus also preferably comprises a densification layer.

[0135] The density of the at least one compressed zone 12 is preferably 10-90% higher, more preferably 20-90% higher and most preferably 40-90% higher than the density of the uncompressed zone of the solid cellulose foam 1 .

[0136] In some embodiments, the density of the compressed region 12 is 20-80% greater than the density of one or more uncompressed regions.

[0137] When a solid cellulose foam is compressed, as described above, the density in the compressed area will increase. This will increase the stiffness and improve 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 characteristics due to the material's shock absorbing properties. However, upon compression, the cushioning properties of the solid cellulose foam begin to decrease as the open cell structure of the foam deforms. If the degree of compression is high, such that the solid cellulose foam is compressed to about 30% or less of its original thickness, the cushioning properties can be severely affected. Therefore, it is important to tailor the degree of compression to the goods or items to be protected.

[0138] Depending on the degree of compression and other conditions (such as relative humidity and compression time), the solid cellulose foam may recover part or all of its original thickness when the pressing tool has been removed. This is especially true when the degree of compression is low, so that the solid cellulose foam is compressed to no more than 90% of its original thickness. The higher the degree of compression, the more deformation occurs in the foam and the ability to recover any original thickness will gradually decrease. In one embodiment, the optimal degree of compression is in the range of 10-90% (e.g., 20-80%) of the original thickness, resulting in no recovery or slight recovery of the original thickness after the pressing tool is removed. However, the compressed foam will have improved resilience compared to the uncompressed foam. That is, the compressed foam will be able to recover its compressed thickness to a high degree, for example, when impacted. This is important when keeping the packaged items in place, and also during impact.

[0139] like Figure 2 As shown in FIG. 1 , the formed solid cellulose foam 1 may comprise compressed areas 12A, 12B having different sizes, the compressed areas 12A, 12B having different depths 43A, 43B, resulting in the corresponding voids VA, VB having different volumes.

[0140] The thickness of the compressed material 15A, 15B in the compressed regions 12A, 12B may also be different and are shown as CMTA and CMTB, respectively.

[0141] The different thicknesses CMTA, CMTB correspond to the different densities of the compressed materials 15A, 15B.

[0142] The at least one pressing tool 4 preferably has the same shape as the shape of at least a portion of the object to be protected by the formed cellulose foam.

[0143] In some embodiments, the formed cellulose foam comprises two halves arranged to fit tightly around the exterior of the item to be protected. The halves may be identical or exhibit differences.

[0144] The pressing step may be repeated one or more times in order to provide the solid cellulose foam 1 with additional compressed areas 12 .

[0145] In some embodiments, it may be preferred to use a second pressing tool having a pressing area of ​​a different size compared to the area of ​​the first pressing tool or having a different shape compared to the shape of the first pressing tool, and to press the pressing tool having the said different size / other shape into one or more already compressed areas.

[0146] In some embodiments, the at least one compressed zone 12 extends to at least one edge E of the cellulose foam. Figure 1a -b).

[0147] In some embodiments, the void V of the at least one compressed zone 12 has the shape of a cavity, which may not be in direct contact with the edge E of the solid cellulose foam 1 (e.g. Figure 3a ).

[0148] Embodiments are conceivable in which the solid cellulose foam 1 comprises different types of compressed areas 12 on different parts of the solid foam 1, such as compressed areas and cavity areas extending to at least one edge E of the foam 1. The shape and design of the article to be protectively packaged determines the shape, number and type of compressed areas.

[0149] Unlike the pressing of thermoplastic foams, the pressing can preferably be carried out without adding any heat. Neither the at least one pressing tool nor the solid cellulose foam needs to be heated. Since no heating is required, a simple and energy-efficient pressing process is possible.

[0150] In a second aspect, the present invention relates to a product made from solid cellulose foam, wherein the product comprises at least one compressed zone.

[0151] Preferably, the density of the compressed area 12 is at least 10%, preferably 20-90%, more preferably 40-90% higher than the density of the uncompressed area or areas. The density may be even higher, for example 50% or more higher.

[0152] In some embodiments, the density of the compressed region 12 is 20-80% greater than the density of one or more uncompressed regions.

[0153] 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 side wall 113 of the foam comprise a densified outer layer. Preferably, the surface 11, e.g. the upper surface 110, wherein at least one cutting line 2 is provided and wherein at least one compression zone 12 is formed comprises a densified outer layer.

[0154] The solid cellulose foam preferably comprises:

[0155] a) 71-95 wt% of cellulose fibers, calculated on the total weight of the solid content of the foam,

[0156] b) 4 to 24 wt% of a water-soluble thickener, calculated on the total weight of the solid content of the foam, and

[0157] c) at least two surfactants.

[0158] The cellulose fibers of the product are selected from wood pulp, regenerated cellulose fibers, and plant fibers; preferably selected from softwood pulp (eg softwood kraft bleached pulp), chemical thermomechanical pulp (CTMP) and dissolving pulp or a combination thereof.

[0159] In some embodiments, 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. In these embodiments, the at least one void V may preferably be the sum of the respective voids of the two or more parts.

[0160] Figure 3aA half of a product comprising two identical halves is shown, and wherein the voids V of each half together form a larger void when the two halves are connected to each other. The respective upper surfaces 110 of each half are arranged to be fixed to each other (e.g. glued) after the item to be protected has been placed in the first of the halves and the second half has been arranged with its upper surface 110 to the corresponding surface 110 of the first half.

[0161] The product of the present invention may preferably be used as a protective cover for articles or goods to be packaged. Fragile articles may particularly benefit from the use of the product defined by the claims, as the compression zone provides additional support to hold the article or goods in place, enabling improved protection of the article as it is tightly held in place by the compression zone.

[0162] It is conceivable that the solid cellulose foam provided in step a) is pre-compressed to a certain extent, for example in order to increase the density and thus the strength of the solid cellulose foam, and that method step c) is carried out on the already compressed foam.

[0163] It will be appreciated that according to the method and product of the present invention it is not desirable to have a through cut line, i.e. a cut line having a cutting depth equal to (or nearly equal to) the thickness X of the solid cellulose foam material 1. The reason for this is that it would not be possible to carry out the pressing step c while at the same time maintaining the compression zone 12 as a fixed and integrated part of the solid foam. Instead, the compression zone 12 would be a loose fitting part contained in the solid foam material 1 with the risk of coming loose and leaving the solid foam material, which could result in the packaged goods being subjected to shocks and vibrations.

[0164] Example

[0165] Example 1

[0166] A solid cellulose foam board with a thickness of 45 mm was pre-cut into shapes with a surface area of ​​76 x 76 mm and different depths (Table 1, "cutting depth"). The pre-cut pattern of the cellulose foam board was then pressed manually using a 2 kg weight with a pressing area corresponding to the surface area of ​​the pre-cut pattern. The cellulose foam was dry, had a density of 32-35 kg / m 3 The density is in the range of 1000 Å and contains 83-88 wt% cellulose fiber (softwood bleached kraft pulp), 10-15 wt% thickener (CMC) and about 2 wt% surfactant (a mixture of myristic acid and sodium cocoyl sarcosinate). No heat is applied during pressing.

[0167] The weight was pressed to different depths for different times (Table 1, "Depth of Pressing"). After pressing, the weight was removed. The thickness of the foam in the compressed area was measured 30 seconds (Table 1, "Depth after 30 seconds") and 24 hours (Table 1, "Depth after 24 hours") after the pressure was removed.

[0168] The results are summarized in Table 1. All depths are measured as the height of the remaining foam measured from the bottom of the plate.

[0169] Table 1

[0170] Sample Cutting Depth Pressing time Pressing depth Depth after 30 seconds Depth after 24 hours 1 20 10 seconds 25 30 33 2 20 1 minute 25 30 31 3 20 10 minutes 25 27 29 4 20 30 minutes 25 25 28 5 10 10 seconds 20 25 27 6 20 10 seconds 25 25 28 7 30 10 seconds 30 30 30 8 40 10 seconds 40 40 40

[0171] Cellulose foam sheets can be pressed to different depths and the shape is retained after the pressure is removed. Due to the pre-cutting, all edges of the pressed area are sharp and clearly defined.

[0172] As will be appreciated by those skilled in the art, numerous changes and modifications may be made to the above-described embodiments and other embodiments of the invention without departing from the scope of the invention as defined by the appended claims.

[0173] It should be noted that the above described aspects may be the subject of their own protection in a separate divisional application. Therefore, it is foreseeable that this aspect of the invention may require its own protection, for example, because it may also be applicable to other concepts than those defined by the independent claims of the present application.

Claims

1. 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 (1); b. providing at least one cutting line (2) having a predetermined cutting depth (DC) into at least one surface (11) of the solid cellulose foam (1), whereby the at least one cutting line (2) defines at least one pattern (3) on the at least one surface (11); and c. Pressing at least one pressing tool (4) into the at least one pattern (3) of the at least one surface (11) of the cellulose foam (1), thereby forming at least one compressed area (12).

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

3. The method according to claim 2, wherein the predetermined cutting depth (DC) of the at least one cutting line (2) is 90% or less, preferably 70% or less, and more preferably 60% or less of the thickness (X) of the cellulose foam.

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

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

6. The method according to any one of the preceding claims, wherein the density of the uncompressed zone (10) of the solid cellulose foam is in the range of 10 to 80 kg / m 3 , preferably 10-60kg / m 3 , and more preferably 20-50kg / m 3 within the range.

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

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

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

11. Method according to any of the preceding claims, wherein the at least one compression zone (12) has the shape of a cavity (C).

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

13. The method according to any of the preceding claims, 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 method according to any one of the preceding claims, wherein the solid cellulose foam (1) comprises: a. 71-95 wt% cellulose fibers, calculated based on the total weight of the solid content of the foam, b. 4-24 wt% of a water-soluble thickener, calculated on the total weight of the solid content of the foam, and c. At least two surfactants.

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

16. A product made from solid cellulose foam (1), wherein the product comprises at least one compressed zone (12), the at least one compressed zone (12) having a density that is 10%-90% higher, more preferably 20-90% higher, and most preferably 40-90% higher than the density of an uncompressed zone (10) of the solid cellulose foam.

17. The product according to claim 16, wherein the solid cellulose foam (1) comprises: a. 71-95 wt% cellulose fibers, calculated based on the total weight of the solid content of the foam material, b. 4-24 wt% of a water-soluble thickener, calculated on the total weight of the solid content of the composition, and c. At least two surfactants.

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

19. The product according to 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).

Images