Method for manufacturing cellulose products using a pressure molding device, pressure molding device and cellulose products

Abstract

To provide a method and an apparatus for manufacturing a cellulose product having a flat or non-flat product shape by a pressure molding apparatus including a forming mold, and the cellulose product.SOLUTION: A method for manufacturing a cellulose product having a non-flat product shape by a pressure molding apparatus having a forming mold having a preheated positive non-flexible forming mold part 2a and a negative non-flexible forming mold part, the forming mold having a forming surface defining a product shape comprises the steps of: arranging a loose and separated cellulose fiber 1a containing water of less than 45 mass at a location for forming in the forming mold in an initial open state; heating the loose and separated cellulose fiber in the forming mold to a forming temperature in a range of 100°C to 200°C; and pressing the loose and separated cellulose fiber by means of the forming mold with a forming pressure acting on the cellulose fiber being loosed and separated across the forming surface, the forming pressure being in a range of 1 MPa to 100 MPa.SELECTED DRAWING: Figure 2a

Description

[Technical field]

[0001] TECHNICAL FIELD TO WHICH THEINVENTION BELONGS The present disclosure relates to methods for producing cellulosic products from wood pulp, apparatus for producing such cellulosic products, and the cellulosic products.

[0002] 2. Background of the Invention In many situations, it is desirable to provide objects of two-dimensional (2D) or three-dimensional (3D) shape made from sustainable materials. One such situation concerns packaging of sensitive goods, such as mechanically precise items, electronic devices, and other household and hardware items, that require protective packaging to avoid damage to the sensitive goods, for example, by mechanical shock, vibration, or compression, during transportation, storage, or other handling. Such packaging typically requires a protective insert shaped to fit the contained goods, so that the goods are securely held within the package. Such inserts are typically made of expanded polystyrene (EPS), a light petroleum-based material, and not considered a sustainable material.

[0003] A commonly used low-cost material for packaging inserts is molded pulp. Molded pulp has the advantage of being considered a sustainable packaging material, since it is produced from biomaterials and can be recycled after use. As a result, molded pulp is rapidly gaining popularity in both primary and secondary packaging applications (packaging in close contact with the article and collections of such packages). Molded pulp is generally formed by immersing a suction mold in a pulp suspension under suction, whereby a mass of pulp is formed in the shape of the desired article by the deposition of fibers. The suction mold is then withdrawn from the suspension, and the suction is typically continued while the remaining liquid is drained, compacting the deposited fibers.

[0004] A drawback common to all wet molding techniques is the need to dry the molded part, which is a time and energy consuming process. Another drawback is that strong interfiber bonds, often described as hydrogen bonds, form between the fibers in the material, which limits the flexibility of the material.

[0005] Additionally, many of the latest lean manufacturing lines require in-line and on-demand packaging or component manufacturing, where wet-forming processes are not preferred.

[0006] Recently, new fiber-based materials have been developed to enable dry molding of three-dimensional objects. One approach is disclosed in International Publication No. 2014142714 (WO2014142714A1). International Publication No. 2014142714 (WO2014142714A1) discloses a dry-laid composite web, an intermediate product for thermoforming three-dimensional shaped objects, containing 40-95% by weight of CTMP fiber, 5-50% by weight of thermoplastic material, and 0-10% by weight of additives, and the dry-laid composite web is impregnated with a dispersion, emulsion or solution containing a thermoplastic material, a polymer, and dried to obtain a dry-laid composite web having a density of 50-250 kg / m 3 When compressed by calendering, the density is 400-1000 kg / m 3 According to WO2014142714A1, the polymer bonds are activated by the higher temperatures applied in the thermoforming process and contribute to the final strength of the thermoformed object.

[0007] Although the polymers described in WO2014142714A1 contribute to the final strength and allow the formation of dry webs, such thermoplastic components eliminate the sustainable function of cellulose, since the composite is not recycled. This drawback is also true when renewable and compostable bioplastics, such as polylactide (PLA), are used as proposed by WO2014142714A1, because the logistics for recycling the material are not available.

[0008] Recent research studies and political decisions, such as the Paris Agreement on Global Warming 2015, stipulate that the carbon footprint of consumed objects and packaging is strongly influenced by the recycling and reuse potential of materials in the so-called Life Cycle Analysis (LCA). Even renewable materials such as cellulose and PLA must be recycled in order for non-renewable, multi-recycled materials such as polyethylene terephthalate (PET) to meet the criteria.

[0009] Material recycling continues to be gradually established in most parts of the world. Europe boasts a global recycling rate of around 30%, while the United States is at only 10% and many developing countries have yet to start recycling. All recycling efforts have in common a focus on the most frequently used materials such as paper, cardboard, glass, aluminum, steel and PET. These recyclable fractions represent the vast majority of waste, and it is unlikely that other fractions, such as biopolymers, will be established as publicly available recycling streams in the near future.

[0010] Therefore, there is a very high global demand for 3D molded packaging, boxes, cups, plates, bowls, inserts and covers, in renewable and recyclable materials with mechanical properties close to those of plastics.

[0011] ISBN 978-91-7501-518-7 (Helena Halonen, October 2012) investigates one approach to compression moulding commercial chemical wood pulp treated with only water to create a new all-cellulose composite: hydroxyethyl cellulose (HEC). The aim was to study the structural changes during processing and the intricacies of the relationship between the mechanical properties and the nanoscale structure of the final biocomposite.

[0012] During compression molding, high temperature (150°C-170°C) combined with high pressure (45 MPa) significantly increases fibril aggregation, possibly involving cellulose-cellulose fusion bonds, i.e., in the fiber-fiber bond regions, resulting in a biocomposite with outstanding mechanical properties, e.g., improved strength (289 MPa), modulus (12.5 GPa), and toughness (6%) compared to PET strength (75 MPa) and PET modulus (PET 3 GPa).

[0013] Although non-recyclable thermoplastic components have been proposed in WO2014142714A1 and scientific results have been shown in ISBN 978-91-7501-518-7 for molding recyclable cellulose fibers to obtain good mechanical properties, no practical or industrial method has been invented so far that allows the commercial production of cellulose packaging and goods as a recyclable plastic replacement as cardboard with reasonable cycle times.

[0014] Summary of the Invention The object of the present invention is to provide a method for producing a cellulose product, an apparatus for forming a cellulose product and a cellulose product, in which the above-mentioned problems are avoided. This object is at least partially achieved by the features of the independent claims. The dependent claims contain further developments of the method for producing a cellulose product, the apparatus for forming a cellulose product and the cellulose product.

[0015] In many situations, it is desirable to provide objects made of sustainable materials in flat or substantially non-flat shapes. Flat shapes generally refer to two-dimensional shapes, such as the shape of a sheet of material or a blank, and substantially non-flat shapes refer to the shape of an object that is appropriately three-dimensional. One such situation concerns packaging of liquids, dry goods, and various items, where the packaging can be made in a three-dimensional shape or formed from a two-dimensional sheet of material into a three-dimensional shape.

[0016] The present invention relates to a method for producing a cellulose product having a flat or non-flat product shape by a pressure molding device having a mold having a molding surface that defines the product shape, the method comprising the steps of: - placing a cellulose blank containing less than 45% by weight of water in said mold; - heating the cellulose blank to a forming temperature in the range of 100°C to 200°C; and - pressing the cellulose blank with the mold at a molding pressure in the range of 1 MPa to 100 MPa acting on the cellulose blank over the entire molding surface. The present invention relates to the above-mentioned production method,

[0017] The molding pressure can be isostatic or anisostatic.

[0018] According to a further aspect of the present invention, there is provided a method for producing a cellulose product having a non-flat product shape, comprising the steps of: preparing an isostatic pressing apparatus including a pressing mold and a pressing mold having a molding surface defining a product shape; placing a cellulose blank containing less than 45 mass percent water between the pressing mold and the pressing mold; heating the cellulose blank to a molding temperature in the range of 100°C to 200°C; and pressing the cellulose blank against the pressing mold using the pressing mold with a substantially equal molding pressure acting on the cellulose blank across the entire molding surface, wherein the molding pressure is in the range of 1 MPa to 100 MPa.

[0019] It is also possible that the heating and pressing steps are carried out at least partly simultaneously, or that the cellulose blank is preheated and no further heat is applied during pressing.

[0020] The cellulosic product may be, for example, a container or part of a container, such that production of the cellulosic product using a method according to an embodiment of the invention may, for example, replace plastic products that are more difficult to recycle. Thus, the cellulosic product produced using the method of the invention may be, for example, a package, an insert for a package, box, bowl, plate, cup, tray or cover.

[0021] The term "isotropic" should be understood as the volumetric pressure on the heated biocomposite fibers during the process of fibril aggregation being substantially equal at all geometric locations of the final 3D object being fabricated.

[0022] The term "anisotropic" should be understood to mean that the volumetric pressure on the heated biocomposite fibers during the process of fibril aggregation is not equal at all geometric locations of the final 3D object being fabricated.

[0023] The cellulose blanks may be prepared in various forms, e.g., as webs, rugs, felts, loose fibers, foams, sheets, etc. The blanks contain trace amounts (0-10%) of agents to increase strength, reduce moisture absorption, or make the final component hydrophobic, flame retardant, color the component, or otherwise modify the characteristics of the final material. However, the amount of additives should not be problematic in achieving the objective of the invention of making a component recyclable as cardboard.

[0024] The blanks may be produced in a pulp processing plant as rolled rugs.

[0025] The present invention is based on the fact that flat or non-flat cellulose products can be produced more homogeneously with shorter cycle times using an isostatic press molding device. In particular, the inventors have found that, depending on the shape of the desired cellulose product, isostatic pressure acting on the cellulose blank can significantly reduce the holding time required to obtain a final product with the same mechanical properties. The inventors have also found that, depending on the shape of the desired cellulose product, anisostatic pressure acting on the cellulose blank can properly shape the cellulose product and obtain a final product with the desired mechanical properties.

[0026] In this context, it should be noted that the processing time required to obtain acceptable mechanical properties of the final product is related to the humidity of the blank, to a specific temperature and to a specific isostatic or anisostatic pressure.

[0027] Temperatures, preferably between 150°C and 170°C, and pressures, preferably between 3 MPa and 7 MPa, can result in different mechanical properties. For example, at an air humidity of 50% relative humidity, an isotropic temperature of 168°C and an isotropic pressure of 4.8 MPa will result in the formation of hard and rigid components at a holding time of 10 seconds. Lowering the temperature and pressure will result in softer and more flexible components.

[0028] Also, a large amount of water in the blank would significantly increase the retention time. In ISBN 978-91-7501-518-7, a retention time of 20 minutes is described and a substantially wet pulp is used in the study. Experiments have shown that the optimum moisture content in the cellulose blank during processing should be in the range of 0.5% to 10% by weight.

[0029] In severe conditions, where large pressure differentials are present across the blanks during joining, the components will never be tolerant, regardless of the hold time.

[0030] The prior art describes pulp compression devices using conventional presses with hydraulic cylinders that convert hydraulic pressure, called pressure medium, into force on the tool or mold via the piston of the cylinder. When molding non-planar objects such as hollow 3D objects, the mold has a convex mold part, a concave mold part, and a cavity between them that represents the desired thickness and shape of the component (called the mold cavity), which is compressed by the force from the piston. In such shape-defined compression devices, if no compensation is made for component thickness vs. processing pressure, large differences in local pressures will occur in the blank during heat treatment. This can result in non-uniform component quality and unacceptable production cycle times in most industrial cases in shape-defined compression devices that are not compensated for isotropic pressure.

[0031] Furthermore, the inventors have found that when using the isostatic pressure method, the required pressure level can be significantly reduced. In ISBN 978-91-7501-518-7, a hollow hemisphere is used as a reference for the study in a shape-defined compression device at 45 MPa and 20 minutes. The internal pressure of the blank in the mold cavity is very high at the top (near the poles) and close to zero at the bottom (adjacent to the equator). The inventors have now surprisingly found that by using isostatic pressure, objects can be produced at one-tenth the pressure used, with a holding time of a few seconds.

[0032] According to various embodiments of the invention, the cellulose blank may comprise wood pulp. Although so-called mechanical pulp can be used for the cellulose blank, it has been found that chemical wood pulp leads to a product with better material properties.

[0033] In one embodiment, the cellulose blank comprises at least 90 percent by weight wood pulp and therefore may be made almost exclusively from readily recyclable materials.

[0034] According to various embodiments, the pressure mold advantageously includes a flexible membrane, and the pressure molding device further includes a fluid control device for controlling a fluid to apply an isotropic pressure to the cellulosic blank through the fluid-impermeable membrane.

[0035] It should be noted that in this context, the term liquid includes both liquids and gases.

[0036] In some embodiments, the molding apparatus may contain a high pressure fluid in an enclosure partially surrounded by a membrane. By increasing the amount of fluid in the enclosure and / or decreasing the size of the enclosure, the pressure of the fluid is increased. As the pressure of the fluid increases, the isotropic pressure acting on the cellulose blank increases.

[0037] Thus, the fluid control device may be an actuator which compresses a fluid, or a fluid flow control device which is controllable to allow pressurized fluid to enter a pressure chamber, the pressure chamber having a flexible membrane as part of its wall.

[0038] In some embodiments, the membrane may be an integral part of the apparatus and may be used during multiple pressing operations.

[0039] In other embodiments, the membrane is fixed to the cellulose blank during pressing, for example by an adhesive, and the method may further comprise the step of providing a new membrane following the pressing step. In these embodiments, the membrane may be provided, for example on a roll, and applied to the manufactured product to add functionality to the product.

[0040] In yet another embodiment, the membrane described above may be provided on a cellulose blank.

[0041] According to a further aspect of the present invention, there is provided an isostatic pressing apparatus for producing a cellulose product having a flat or non-flat product shape starting from a cellulose blank, the isostatic pressing apparatus comprising a mold having a molding surface defining the product shape, and a fluid control device for controlling a fluid to apply isostatic pressure to the cellulose blank to press it against the molding surface.

[0042] The mold may include a negative molding mold portion and a negative pressure mold portion.

[0043] The mold may include a negative mold portion and a positive pressure mold portion.

[0044] The invention also relates to a cellulose product produced by the method described. The cellulose product may have a flat or substantially non-flat shape.

[0045] According to one embodiment of the present invention, the isostatic pressure is obtained with a power-driven compression device, wherein said compression device includes a flexible barrier or membrane surrounding the blank and isolating it from the pressure medium, e.g. gas, hydraulic oil, water to be packed, beverage, elastomeric or dilatant material.

[0046] The method and apparatus according to the embodiments of the present invention relate to the blow molding of hollow 3D objects such as bottles, milk packages, cans and jars. Traditional cellulose-based packages for dairy products and juices are facing competition from blow molded PET bottles. Although cellulose and paper-based packages are renewable and recyclable, the popularity of folded paper packages has been limited by the moldability of blow molded PET.

[0047] According to the blow molding embodiment, the apparatus comprises at least two concave molds surrounding the cellulose fibers and a single-use film layer barrier that becomes an integral part of the final component, where the cellulose fibers and the film layer barrier are provided to the mold cavity in a tubular shape, where the film layer barrier isolates the pressure medium from the cellulose fibers during filling in the tubular shape, and where the pressure medium is pressurized to apply isotropic pressure to all parts of the cellulose fibers towards the mold.

[0048] The present invention thus provides a method, a tubular shaped blank, a blow molding apparatus, and a renewable package having similar properties to thermoplastics, said package being recyclable as paper and cardboard.

[0049] Such a blow moulding device may preferably constitute a filling device on-site at a dairy, brewery or juice factory, using the beverage or liquid to be filled as said pressure medium.

[0050] According to another embodiment, the isostatic pressure is obtained in a shape-defining compression device having two rigid moulds, one convex and one concave, where the shape of the final three-dimensional object is defined by a cavity between the closed moulds, the thickness of said cavity or the thickness of said blank being designed to apply an isostatic pressure to all parts of the cellulose fibres towards said moulds.

[0051] These and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. [Brief description of the drawings]

[0052] [Figure 1] 1a-1c show schematic diagrams of a conventional pressing method, compression apparatus and components. [Figure 2a] FIG. 2a illustrates a schematic of an alternative configuration of a compression device using a multi-use membrane, showing an initial stage according to an exemplary embodiment of the present invention. [Figure 2b] FIG. 2b illustrates a schematic of an alternative configuration of a compression device using a multi-use membrane showing the compression stage according to an exemplary embodiment of the present invention. [Diagram 3] 3a-b are schematic illustrations of alternative configurations of a compression device including an integrated barrier of single use material showing the initial stage (a) and the compression stage (b) according to an exemplary embodiment of the present invention. [Figure 4] 4a-d show schematic diagrams of alternative configurations of compression apparatus and components using an integrated barrier and blow molding of a single-use material showing the initial stages (a and b) and compression stage (c) according to an exemplary embodiment of the present invention. [Diagram 5] 5a-b illustrate schematic diagrams of an alternative configuration of a compression device using a multi-use membrane, showing the initial stage (a) and the compression stage (b) according to an exemplary embodiment of the present invention. [Figure 6] 6a-6c illustrate schematic diagrams of alternative configurations of a compression device with cavity compensated pressure control showing the initial stages (a and b) and the compression stage (c) according to an exemplary embodiment of the present invention. [Figure 7] 7a-b illustrate schematic diagrams of an alternative configuration of a compression device with blank thickness compensation, showing the initial stage (a) and the compression stage (b) according to an exemplary embodiment of the present invention. [Figure 8] Figures 8a-c show diagrammatically an alternative configuration of the compression device, using a large flexible membrane. [Figure 9] 9a-c show diagrammatically another alternative configuration of the compression device, using a large flexible membrane.

[0053] Description of exemplary embodiments Various aspects of the present disclosure are described below in conjunction with the accompanying drawings, which illustrate, but do not limit, the present disclosure, where like designations refer to like elements and variations of the described aspects are not limited to the specifically illustrated embodiments but may be applicable to other variations of the present disclosure.

[0054] The detailed description of the present invention describes a method for producing a cellulosic product, a pressing apparatus, and a cellulosic product.

[0055] Various embodiments of sheet material or blanks according to the present disclosure are primarily discussed with respect to cellulose blanks placed in a flat shape in a mold for shaping. It should be noted that this is in no way limiting to the scope of the invention, which also includes blanks that have been pre-shaped, for example, into a three-dimensional object. For example, the blanks may be provided to the mold in a shape that resembles the desired final shape of the object. Another embodiment may include cellulose blanks that are provided to the mold in the form of a web on a roll.

[0056] Planar shape refers to a generally two-dimensional (2D) shape, such as the shape of a blank or sheet material, and substantially non-planar shape may refer to a suitable three-dimensional (3D) shape. Objects according to the present disclosure may be made in two-dimensional shapes, three-dimensional shapes, or may be formed into three-dimensional shapes from two-dimensional blanks or sheet material.

[0057] Furthermore, by illustrating a coherent sheet of cellulose fibers diagrammatically, this is in no way intended to limit the scope of the invention, which similarly includes, for example, a blank comprising loose, separated fibers that is applied to a mold.

[0058] In the detailed description of the invention, the three-dimensional objects to be formed and various embodiments of the molds for forming the objects according to the invention are primarily discussed in terms of hollow bowls, hollow cups or hollow bottles having a generally uniform thickness. It should be noted that this is in no way limiting the scope of the invention, which includes complex shapes, solid parts or large objects with, for example, different thicknesses as well. For example, the objects may advantageously include stiffeners, folds, holes, 3D shaped text, hinges, locks, threads, snaps, feet, handles or surface patterns.

[0059] 1a-1c show a conventional pressing method, compaction apparatus, and a component produced by an anisostatic pressing method and apparatus.

[0060] FIG. 1a is a schematic side view of a prior art compression device having an upper concave mould 102b, a lower convex mould 102a and a cellulose fibre sheet 101a in an uncompressed state.

[0061] FIG. 1b is a schematic side view of a prior art compression apparatus in a compressed state having an upper concave mould 102b, a lower convex mould 102a and a cellulose fibre sheet 101a, partially compressed with force F to form a desired final shape 101b using heat and pressure P.

[0062] By convention, the thickness of the final component 101b is uniform, and therefore the thickness t of the cavity between the two molds 102a and 102b is 1 =r b -r a Since conventional tools for compression are made of rigid metal or similar inflexible materials, and dry cellulose fibers do not behave as a pressure equalizing fluid, the pressure P in the cavity depends on the volume of the blank 101 and the principles of local pressure generation.

[0063] Pressure P 2 and P 5 The principle of local pressure generation at is defined by the force F. 4 The principle of local pressure generation at is defined by the geometry of the cavity and the volume of the blank 101 in question. 3 is found by combining the principles of force and shape-defining pressure generation.

[0064] P 4 Such shape-defined pressures are highly dependent on the actual current volume of the blank 101. Usually small stochastic variations in the local material supply will have a large effect on the resulting local pressure. Dynamically defined pressures have a linear gain and are a much more robust process for industrial applications.

[0065] 1c shows a three-dimensional object, component, hemisphere 101b, produced by the conventional compression method described above. As the blank 101a bends over the lower forming mold 102a, some of the blank 101a may stretch, so that when the upper pressing mold 102b closes the tooling over the blank 101a, the mechanical properties change at the position 101b P of the final component 101b. 4 and position 101b P 2 It differs from.

[0066] A power-directed compaction device according to an exemplary embodiment of the present disclosure will now be described with reference to Figures 2a-b. In Figure 2a, a schematic side view of a compaction device or pressure moulding device in the form of a mould 3 for cellulose fibres using heat is shown in an open state. The compaction device or mould may be configured such that an isotropic pressure is applied when moulding the cellulose product. Alternatively, the applied pressure may be non-isotropic such that different pressure levels are applied to different parts of the mould 3 when moulding the cellulose product. The mould 3 has at least one moulding surface which defines the shape of said product.

[0067] The mold 3 of this embodiment of the disclosure uses one rigid mold part 2a positioned under a multi-use membrane 4. The membrane 4 constitutes a seal for a pressure medium or fluid 5, such as hydraulic oil, contained in a pressure chamber, not shown. The membrane 4, also called a diaphragm, may preferably be made of rubber, silicone, elastomer or polyurethane.

[0068] Similar presses are found in completely different industries, for example in the forming of metal sheets for aircraft or in the processing of metal powder into a homogeneous material. For example, isostatic presses for conventional purposes usually use very high pressures, for example in the range of 1000-2000 bar.

[0069] A cellulose blank 1a, which mainly comprises cellulose fibres together with some additives and reagents, is placed in the gap between a membrane 4 and a rigid mould part 2a, which in Fig. 2a is placed below the membrane 4. The cellulose blank 1a also contains a large amount of moisture, which may vary depending on, for example, the humidity of the surrounding atmosphere.

[0070] To form a cellulose product or a part of a cellulose product from the cellulose blank 1a, the cellulose blank 1a is heated to a forming temperature T 1 (which may range from 100° C. to 200° C.). 2 The cellulose blank 1a is heated to a temperature T 1 The mold 3 can be preheated, for example, to a temperature of 150° C. to 170° C. by pumping heated oil through the internal channel 7 of the mold part 2a. An alternative way to preheat the mold 3 is to use an integrated electrical resistor, not shown. The cellulose blank 1a can also be preheated, for example, by using infrared radiation before being placed in the tool. It is also possible to preheat the pressure medium 5 to a pressure medium temperature T 5 Heating to room temperature may also be a suitable alternative.

[0071] In FIG. 2b, hydraulic oil 5 is pressurized to a pressure of at least 1 MPa, and membrane 4 encases heated mold 2a together with compressed material 1b to form a cellulose product therebetween. The appropriate pressure P 1 The suitable pressure P may be in the range of 1 to 100 MPa. 1 The cellulose fibers are compressed by applying a pressure P 1The pressure may be uniform or isotropic, so as to compress the cellulose fibers uniformly, regardless of their relative position on the mould 2a or the actual local mass of the fibers. In an alternative embodiment, the pressure may be non-isotropic, with different pressure levels being used in different parts of the mould 3 to mould the cellulose product. This may be used, for example, when different structural properties are desired in different parts of the cellulose product.

[0072] The compression device may comprise a fluid control device (not shown), which may be an actuator that compresses the fluid 5, or may be a controllable fluid flow control device such that pressurized fluid 5 enters a pressure chamber having a flexible membrane 4 as part of its wall. The device may contain the fluid 5, or the fluid 5 may be air drawn from the surrounding atmosphere.

[0073] The inventors have demonstrated that the cellulose product is molded at a temperature of 160° C. and a pressure P of 4 MPa (40 bar). 1 They found that the addition of cellulose acetate resulted in fibril aggregation in cellulose fibres after a 10 second hold time that was comparable to that of many thermoplastics.

[0074] In order to reduce the cycle time of the industrial production of cellulose products from the compressed material 1b, the cooling of said compressed material 1b can be carried out, for example, by forcing cooled oil into the internal channels 7 or pressure chambers arranged in the mould part 2a, in which case the temperature T 2 and the temperature T of the pressure medium 5 5 can decrease rapidly.

[0075] The process and the apparatus are configured to pump the pressure medium 5 to atmospheric pressure P 0 2a, whereupon the membrane 4 returns to its more or less flat initial state, the finished cellulose product is removed and unwanted residual compressed or uncompressed cellulose fibres can preferably be cut away and removed.

[0076] Final thickness of cellulose product t 1 may vary slightly depending on the actual local amount of cellulose fibers.

[0077] In another embodiment, a rigid mold section may be used instead of a flexible or pliable membrane 4, which may be appropriate when different pressure levels are desired in forming the cellulosic product. The use of a flexible membrane 4 results in an isotropic compression process, which results in a uniform cellulosic product with high strength and short production cycle times.

[0078] One difference between the compression method and apparatus of the present invention in using isostatic pressure and that of the prior art method and apparatus of Figures 1a-1b is the use of a flexible or pliable membrane 4 instead of the rigid upper mold 102b. The isostatic compression method and apparatus results in homogeneous components with high strength and short manufacturing cycle times.

[0079] Above, one exemplary embodiment of the isostatic compression method and apparatus has been described with reference to Figures 2a-b. It should be understood that the molding of all-cellulose composite three-dimensional objects using hot compression molding of water-only treated wood pulp can be performed isostatically in other ways as well.

[0080] 3a-3b, the multi-use membrane 4 of FIGS. 2a-2b is replaced by a single-use membrane comprising a thin film barrier 6, whereby said barrier 6 is either pre-applied to the cellulose blank 1a during production of the cellulose blank 1a or the membrane barrier 6 may be fed to the compression apparatus, for example from a roll not shown, and applied to the cellulose blank 1a while the cellulose blank 1a is under isostatic pressure.

[0081] The thin barrier 6 is made of a thermoplastic material such as PET or PLA and may have a thickness in the range of 1-700 μm.

[0082] FIG. 3 a includes a compression apparatus or mould 3 in its initial open state, using a thin film barrier 6 applied to cellulose fibres 1 a, at a temperature T 2 1 shows a schematic of the method, comprising a lower, concave mould part 2b preheated to 0.5° C. and a pressure medium or fluid 5, preferably gas or air at atmospheric pressure, contained in a pressure chamber (not shown).

[0083] FIG. 3b shows the same device and cellulose blank 1a as shown in FIG. 3a in a compressed state, with the pressure medium 5, preferably compressed air or a non-contaminating liquid such as water, being applied at a pressure P 1 , the thin barrier layer 6 isolates and seals the pressure medium from the compressed material 1b of the cellulose blank 1a, and the pressure medium 5 and membrane 6 are pressed against the temperature T 2 This applies equal pressure to the cellulose fibers over the entire heated forming surface.

[0084] For a certain time X, temperature T 1 The pressure P is equal to 1 By holding the pressure P 1 is 4 MPa (40 bar), and the molding temperature T 1 is 140° C., and the temperature T 2 is 160° C. and the time X is 10 seconds, a biocomposite component of compressed material 1b is obtained with mechanical properties close to those of thermoplastics.

[0085] The pressure medium 5 is removed, and after a time X, the atmospheric pressure P 0 By reducing the pressure to 100° C., the cellulose product formed by the compressed material 1b can be removed and cut to its final shape if desired.

[0086] One advantage of the method discussed in Figures 3a-b is that the membrane barrier 6 can also act as a barrier against other media to which the components are exposed during use of the product. For example, if the cellulosic product with the membrane barrier 6 is a takeaway salad bowl, it will protect the cellulosic fibers in the compressed material 1b from contact with vegetables and reduce the moisture absorption properties of the bowl. The method can also be used to manufacture bottles or containers for liquid products, and thus the cellulosic product may be suitable for packing various types of liquids or beverages, including carbonated liquids.

[0087] 4a-4d, the mould 3 comprises at least two openable concave moulding surfaces or portions 2a, 2b surrounding a tube-shaped cellulose blank 1a comprising a membrane barrier 6, where the outer layer is uncompressed cellulose 1a fibres with additives and the inner layer 6 is a single-use membrane comprising a thin film barrier 6. The blank can be fed from a roll (not shown), preferably in flat shape, to the compression device, where it is formed into the shape of a tube (not shown), surrounding a pressure medium nozzle 8.

[0088] In FIG. 4a, a mold 3 having molding surfaces or portions 2a, 2b is heated to a mold temperature T 2 3 and is shown diagrammatically in an open initial stage of the forming process method. The tubular shaped cellulose blank 1a with the membrane barrier 6 is fed from the top surrounding the fixed pressure medium nozzle 8, which means that the tubular shaped cellulose blank 1a with the membrane barrier 6 is fed from above in the direction towards the forming surfaces 2a, 2b.

[0089] The preheated mold 3 is closed by a closing force F c This force is generated by the pressure P applied to the inside of the mold 3 on the basis of the pressure medium from the pressure medium nozzle 8 shown in FIG. 1 The closing force F is larger than the opening force generated by the mold 3 having the molding surfaces 2a and 2b in a closed state, as shown in FIG. cThe internal volume of the cellulose blank 1a is increased by the external pressure P 0 In another embodiment, the cellulose blank may be cut from the remaining material by the mould 3 when it is closed.

[0090] FIG. 4c shows the fibril aggregation phase and shaping of the method of the invention, where the internal volume of the blank is filled with pressure medium 9 from a pressure medium nozzle 8 and pressure P 1 where a pressure medium 9 and a single-use membrane 6 apply equal pressure to the cellulose fibres across the heated moulding surfaces 2a and 2b of the mould.

[0091] The filling process is carried out during the steps shown in Figures 4b and 4c, where air channels 10 are required to allow the air outside the cellulose blank 1a with the membrane barrier 6 in the cavity of the mould 3 to be evacuated during the expansion process of the blank.

[0092] FIG. 4d shows a three-dimensional cellulose product in the form of a hollow object made from compressed material 1b and a membrane barrier 6, for example a beverage bottle formed by the method described in FIGS. 4a-4c filled with the pressure medium 9, which membrane barrier 6 separates the pressure medium 9 from the compressed cellulose fibers 1b.

[0093] According to the present disclosure, the pressure medium 9 is constituted by the beverages intended to be filled into the cellulosic products, such as milk, juice, water and carbonated drinks.

[0094] The membrane barrier 6 is preferably made of a thin thermoplastic material such as PET or PLA and has a thickness in the range of 1-700 μm, where the membrane barrier 6, also conventionally applied in paper packaging for beverages, seals the cellulose fibers 1b from contact with the beverage 9 during storage and use of the cellulose product.

[0095] The cycle time of the process step shown in FIG. 4c is determined by the temperature T 9 The time can be shortened if the mold 3 having the molding surfaces 2a, 2b is cooled to a molding temperature T 2 and the blank is preheated to a temperature T 1 If the compressed medium is preheated to a temperature T 9 This allows the filled bottle to be removed from the mould 3 in a cycle time of a few seconds or less.

[0096] 5a-5b show a schematic diagram of another principle of the present disclosure, in which a compression device includes at least one convex mold part 2a, at least one concave pressurizing mold part (mold part) 2b, and a multi-use preformed membrane 4, and after the mold parts 2a and 2b surrounding the cellulose blank 1a are closed, a pressure medium 5 applies a pressure P 1 is pressurized to

[0097] The final forming stage, where fibril aggregation occurs in the cellulose fibers of the cellulose blank 1a, is shown in Fig. 5b. The enlarged cross-sectional view shown in Fig. 5b shows how a pressure medium 5 penetrates into the forming mold 3 between the upper concave pressure mold part 2b and the membrane 4, where a pressure P 1 Thus, the cellulose blank 1b is uniformly compressed towards the forming surface of the preheated lower convex pressing mold part 2a. The penetration of the pressure medium 5 can be facilitated by small depressions (not shown) in the surface of the upper concave pressing mold part 2b which act as microchannels for the pressure medium 5.

[0098] If shorter cycle times are preferred, the embodiment of the compression device according to Figures 5a-5b may be more beneficial than the method described in Figures 2a-2b. In the embodiment shown in Figures 5a-5b, it is not necessary to deform the membrane 4 to the same extent.

[0099] An example of the compression method described above includes a flexible membrane 4 that can be used to apply isostatic pressure, with reference to Figures 2-5. It should be understood that molding of all-cellulose composite three-dimensional objects using heat compression molding of water-only treated wood pulp can be done using conventional tooling while still obtaining isostatic pressure.

[0100] 6a-6c, an upper preheated concave non-flexible pressurized mold part 2b and a lower preheated convex non-flexible mold part 2a surround a cellulose blank 1a, where a cavity thickness t(P) between the lower preheated convex non-flexible mold part 2a and the upper preheated concave non-flexible pressurized mold part 2b deviates from a nominal uniform thickness, which deviation has been demonstrated theoretically and / or practically, and where an isotropic pressure P is applied to all parts of the cellulose blank 1a towards the mold parts 2a and 2b when the mold parts 2a and 2b are compressed together with a force F. 1 will be added.

[0101] Figure 6a shows a schematic representation of an embodiment in an initial open state with the cellulosic blank in a flat state of a continuous web 1a fed into the mould sections, Figure 6c shows a schematic representation of an embodiment in a closed state with the cellulosic blank 1a in a compressed non-flat state, and Figure 6b shows a schematic representation of an embodiment intermediate between the open and closed states in an uncompressed non-flat state.

[0102] 6a-6c show an example of a compression apparatus for a hollow bowl, where the convex mold part 2a has a nominal preferred shape and the concave pressurizing part 2b is pressed under equal pressure P 1 The shape is adjusted to obtain

[0103] As shown in Fig. 6b, the blank is deformed by the two mould parts 2a, 2b, and the thickness t of the cellulose blank 1a is changed by friction and residual strain in the cellulose blank 1a. This can be changed in many ways, in this schematic example the cellulose blank 1a has its thinnest thickness t near the cavity entrance of the pressurised mould part 2b. minThe thickness of the mold 2a is the thickest at the top of the mold 2a. max become.

[0104] Therefore, the cellulose blank 1a is pressed by the concave pressing mold part 2b under a substantially equal pressing pressure P acting on the cellulose blank 1a over the entire pressing surface. 1 By pressing the mold 2a against the convex mold 2a, the narrowest cavity thickness s min is the thinnest t of the cellulose blank. min The cavity thickness s is located near the widest max is the thickest t of the uncompressed cellulose blank 1a max , the thickness s of the cavity between the two mold halves 2a and 2b is compensated or adjusted.

[0105] The relationship between the thickness t of the cellulose blank, the thickness s of the cavity, and the final cavity shape also influences the geometric pressure of the cavity. 1 is determined, and the narrowest cavity thickness s min The convexity, thickness and angle of the adjacent cavity determine the final pressure P 1 Determine.

[0106] We consider a substantially isotropic pressure P 1 To obtain the final shape of the cavity, t(P), a complex algorithm is found, in which both mathematical analysis, preferably the Finite Element Method (FEM), and empirical testing, preferably trial and error, are required to obtain equal pressure throughout the component.

[0107] According to another embodiment of the present disclosure that does not use a flexible membrane, the geometrically pressure regulated cavity of Figures 6a-6c can be replaced by thickness compensation (regulation) of the cellulose blank.

[0108] 7a-7b show schematic diagrams of a conventional pressure-unadjusted concave mold part 2b and a non-adjusted convex mold part 2a resulting in a preferably equal nominal cavity thickness t, where the blank is formed according to the same theory and in the same manner as described for the embodiment discussed with respect to FIGS. 6a-6c. min -t max The thickness of the pressure-adjusted film is between 100 and 200 mm.

[0109] The option of creating isostatic pressure without a flexible membrane, as shown in Figures 6a-c and 7a-b, is associated with reduced cycle time and cost of the compression equipment, however, the use of rigid molds may result in more costly development efforts.

[0110] The advantage of using the method described with respect to FIGS. 7a-7b over the method described with respect to FIGS. 6a-6c is that it provides a uniform thickness t 1 However, the blanks may be more costly to produce by the method described in Figures 7a-7b.

[0111] Alternatively, the mould 3 may be formed by a membrane configured as a large thick flexible membrane structure. In Fig. 8a-8c, another mould 3 is shown diagrammatically with a concave mould part 2b and a convex mould part 2a. The convex mould part 2a applies a moulding pressure F to a large thick flexible membrane 4 which is isostatically pressing the cellulose blank 1a when moulding the cellulose product. By large flexible membrane is meant a flexible structure which has the ability to apply isostatic pressure to the cellulose blank 1a similar to the membrane structures described in the above embodiment, but which has a larger elastic deformation area compared to the thinner membrane structures. The large flexible membrane 4 may be configured as a thick membrane structure or may even be made of a homogeneous flexible material mass. The flexible material may have properties such that it floats between the mould parts when pressure is applied to the mass. In the embodiment shown in Fig. 8a-8c, the large flexible membrane 4 is configured of a homogeneous flexible material mass.

[0112] In another embodiment, the large flexible membrane 4 may have a variable thickness, for example by being molded or cast into a structure of variable thickness. Thinner and thicker areas of the large flexible membrane with variable thickness may compensate for areas of the mold part that require smaller or larger deformations of the membrane to equalize or constant the pressure applied to the cellulose blank 1a. The use of a large flexible membrane structure allows the mold to be made with a cheaper and simpler structure.

[0113] The large flexible membrane 4 is configured such that when pressure F is applied from the mould part, the large flexible membrane 4 deforms and exerts an isotropic pressure. The large flexible membrane 4 may be made of a suitable elastomeric material, for example rubber, silicone, polyurethane or other elastomers. Due to the flexibility of the large flexible membrane 4, the large flexible membrane 4 exerts an isotropic pressure on the cellulose blank 1a.

[0114] In Fig. 8a, the cellulose blank 1a is positioned between the concave mould part 2b and the large flexible membrane 4. As shown in Figs. 8a-8b, the convex mould part 2a presses the large flexible membrane 4 and the cellulose blank 1a into the concave mould part 2b when a moulding pressure F is applied to the mould parts. During moulding of the cellulose product, the concave mould part 2b is heated to a mould part temperature T 2 During the molding process, the cellulose blank 1a is heated to a molding temperature T 1 (See Figures 8a to 8c).

[0115] In Figures 9a-9c another alternative mould 3 is shown in schematic form, having a concave mould part 2b and a convex mould part 2a. The concave mould part 2b applies a moulding pressure F to the large flexible membrane 4, which applies an isotropic pressure to the cellulose blank 1a when moulding the cellulose product. The large flexible membrane 4 is configured such that when pressure F is applied from the mould part, the large flexible membrane 4 deforms and applies an isotropic pressure. The large flexible membrane 4 may be of the same structure as described above with respect to the embodiment shown in Figures 8a-8c. In the embodiment shown in Figures 9a-9c, the large flexible membrane 4 has a thickness that varies with the shape of the convex mould 2a. Due to the flexibility of the large flexible membrane 4, the large flexible membrane 4 applies an isotropic pressure to the cellulose blank 1a.

[0116] In Fig. 9a, the cellulose blank 1a is placed between the convex mould part 2a and the large flexible membrane 4. As shown in Figs. 9a-b, the convex mould part 2a presses the cellulose blank 1a into the concave mould part 2b towards the large flexible membrane 4 when a mould pressure F is applied to the mould parts. During moulding of the cellulose product, the convex mould part 2a is heated to a mould part temperature T 2 During the molding process, the cellulose blank 1a is heated to a molding temperature T 1 (See Figures 9a to 9c).

[0117] In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0118] It will be understood that the above description is merely exemplary in nature and is not intended to limit the disclosure, its application, or uses. Although specific examples have been described in the specification and shown in the drawings, those skilled in the art will recognize that various modifications may be made and equivalents may be substituted for the elements without departing from the scope of the disclosure as defined in the claims. In addition, modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope.

[0119] Therefore, the disclosure is not limited to the particular examples shown in the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the disclosure, but the scope of the disclosure will include all embodiments falling within the scope of the foregoing description and the appended claims.

[0120] Reference signs appearing in the claims should not be considered as limiting the scope of the matter protected by the claims, but their only function is to facilitate the understanding of the claims.

Claims

1. A method for producing a cellulose product having a non-flat product shape by a pressure molding device having a mold (3) having a preheated convex non-flexible mold part (2a) and a preheated concave non-flexible mold part (2b), the mold (3) having a molding surface defining the product shape, the method comprising the steps of: placing loose and separated cellulose fibers (1a) containing less than 45 weight percent water in a position for molding in the mold (3) in an initial open state, wherein the cavity thickness between the convex non-flexible mold part (2a) and the concave non-flexible mold part (2b) deviates from a nominally uniform thickness, which deviation causes an isotropic pressure to be applied to all parts of the cellulose blank towards both mold parts when they are compressed together with a force; heating the loose and separated cellulose fibers (1a) in the mold (3) to a molding temperature in the range of 100°C to 200°C; and pressing the loosened and separated cellulose fibers (1a) using the molding die (3) at a molding pressure in the range of 1 MPa to 100 MPa acting on the loosened and separated cellulose fibers (1a) over the entire molding surface; Including, method.

2. 2. The method according to claim 1, comprising the step of placing a cellulose blank (1a) comprising the loose and separated cellulose fibers containing less than 45 percent by weight of water in a position for molding in the mold (3) in an initial open state, the cellulose blank (1a) being a sheet material or a blank having a two-dimensional shape, or the cellulose blank (1a) being molded into a three-dimensional shape from a two-dimensional sheet material.

3. 3. The method of claim 1 or 2, wherein the loose and separated cellulose fibers (1a) contain less than 25 percent by weight of water.

4. 4. The method according to claim 1, wherein the loose and separated cellulose fibers (1a) contain less than 15 percent by weight of water.

5. 5. The method according to claim 1, wherein the loose and separated cellulose fibres (1a) comprise wood pulp.

6. 6. The method according to claim 1, wherein the loose and separated cellulose fibres (1a) comprise at least 90% by weight of wood pulp.

7. 7. The method according to claim 1, wherein the heating step is carried out at least in part before the pressing step.

8. 8. The method according to claim 1, wherein the loose and separated cellulose fibres (1a) are made from chemical wood pulp.

9. 9. The method according to any one of the preceding claims, wherein the loose and separated cellulose fibres (1a) are cut from the remaining material by the mould (3) when the mould (3) is closed.

10. 10. The method according to any one of claims 1 to 9, wherein by the heating and pressing of the loose and separated cellulose fibres (1a), fibril coagulation occurs in the cellulose fibres.

11. 1. A press-molding apparatus for producing a cellulose product having a non-flat product shape starting from loose and separated cellulose fibers (1a), comprising: A mold (3) having a molding surface defining the product shape and having a preheated convex non-flexible mold part (2a) and a concave non-flexible mold part (2b), arranged to carry out the method steps according to any one of claims 1 to 10. Device.

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