SE541995C2

SE541995C2 - Method for forming a cellulose product, cellulose product forming apparatus and cellulose product

Info

Publication number: SE541995C2
Application number: SE1750313A
Authority: SE
Inventors: Linus Larsson; Maria Kruse; Niklas Danielsson
Original assignee: Pulpac AB
Priority date: 2017-03-16
Filing date: 2017-03-16
Publication date: 2020-01-14
Also published as: SE1750313A1

Abstract

A method for forming a cellulose product from a dry formed cellulose blank of cellulose fibres, comprising the steps: adding water and/or one or more material property substances to the cellulose fibres; heating the cellulose fibres to a forming temperature in the range of 140°C to 200°C; and pressing the cellulose fibres with a forming pressure of at least of 4 MPa.

Description

METHOD FOR FORMING A CELLULOSE PRODUCT, CELLULOSE PRODUCT FORMING APPARATUS AND CELLULOSE PRODUCT TECHNICAL FIELD The present disclosure relates to a method for forming a cellulose product from cellulose fibres, a cellulose product forming apparatus for manufacturing a cellulose product from cellulose fibres, and a cellulose product.

BACKGROUND Wet forming of cellulose into flat products, such as cardboard, or non-flat products, such as packages for eggs, has been widely used for a long time. Nevertheless, due to good mechanical properties and low manufacturing costs, plastic materials are preferred over wet formed cellulose in many product applications, for example when producing packages and bottles. Also other disposable product categories, such as hangers for clothes, have traditionally been produced using plastics due to superior mechanical properties vs. product weight for polymeric materials.

Global warming and climate change is forcing the industry to use renewable, non-fossil, compostable and recyclable materials and packaging solutions. Cellulose from wood is one such preferred material alternative.

To be able to replace plastic materials with cellulose, improvements in mechanical properties and reduction of manufacturing cost for cellulose based packages and products are required.

During recent years, several research and development efforts have been performed with the purpose of increasing the field of application for cellulose fibres. Wet forming processes have to deal with the timely challenge to remove water from the wet cellulose fibers that are to be formed in the process. Therefore, R&D attempts have instead covered forming of dry cellulose blanks. In the following text, the expression cellulose blank will refer to a structure formed from cellulose fibres.

Dry forming processes will enable short forming cycle time and is therefore attractive from a manufacturing cost perspective. However, the only known method to create competitive mechanical properties in dry formed cellulose is to add polymers, for example bio-polymers such as Poly Lactic Acid (PLA), to the cellulose.

WO2014142714A1 discloses a dry-laid composite web being an intermediate product for thermoforming of three-dimensionally shaped objects, comprising 40-95 weight percent CTMP cellulose fibers, 5-50 weight percent thermoplastic material, and 0-10 weight percent additives, wherein the dry-laid composite web has been impregnated with a dispersion, an emulsion, or a solution containing the thermoplastic material, polymer, and dried, obtaining a density of 50-250 kg/m3, or, if compressed by calendaring 400-1000 kg/m3.

According to WO2014142714A1, bonding of the polymer is activated by the higher temperature applied in the thermoforming process and contributes to the final strength of the thermoformed object. Although the polymer according to WO2014142714A1 may be contributing to the final strength and enabling forming of dry-laid web, such thermoplastic ingredient will erase the sustainable features of the cellulose, since the composite will not be recyclable. This disadvantage is applicable even if a renewable and compostable bio-plastic, e.g. polylactide (PLA) is used as proposed by WO2014142714A1, since logistics for material recycling is not available.

Other recent research has found that wet formed cellulose can obtain mechanical properties essentially similar to plastics if high temperature and high pressure is applied to the cellulose blank.

In the report ISBN 978-91-7501-518-7 (Helena Halonen, October, 2012) one possible approach to use compression moulding of commercial chemical wood pulps processed with only water has been studied. The objective was to study the structural changes during processing and the complexity of relating the mechanical properties of the final bio-composites to the nano-scale structure. The combination of high temperature (150-170 °C) and high pressure (45 MPa) during compression molding yields a remarkable increase in fibril aggregation, possibly including cellulose-cellulose fusion bonds, i.e. fibril aggregation in the fiber-fiber bond region. This fibril aggregation is resulting in a bio-composite with remarkable mechanical properties including improved strength (289 MPa), modulus (12.5 GPa) and toughness (6%) to be compared to e.g. PET-strength (75 MPa) and PET-modulus (PET 3GPa).

The use of a wet wood pulp as described in ISBN 978-91-7501-518-7 is not optimal from an energy consumption or timing perspective, since long cycle times at high temperatures are needed when forming the cellulose product under high pressure. Therefore, cellulose products produced with this method will not be commercially attractive.

In view of the above-mentioned and other drawbacks of the prior art, it is an object of present invention to provide a cost and energy efficient production method of cellulose products with short cycle times, providing a rational production of cellulose products with improved mechanical properties.

SUMMARY An object of the present disclosure is to provide a method for forming a cellulose product, a cellulose product forming apparatus, and a cellulose product, where the previously mentioned problems are avoided. This object is at least partly achieved by the features of the independent claims. The dependent claims contain further developments of the method for forming a cellulose product, the cellulose product forming apparatus and the cellulose product.

The disclosure concerns a method for forming a cellulose product from a dry formed cellulose blank of cellulose fibres, comprising the steps: adding water and/or one or more material property substances to the cellulose fibres; heating the cellulose fibres to a forming temperature in the range of 140°C to 200°C; and pressing the cellulose fibres with a forming pressure of at least of 4 MPa.

With dry forming of the cellulose blank is meant a process in which cellulose fibres are air-laid to form the cellulose blank. When forming the cellulose blank in the air-laid process, the cellulose fibres are carried and formed to the blank structure by air as carrying medium. This is different from a normal papermaking process, where water is used as carrying medium for the cellulose fibres when forming the paper structure. In the air-laid process, water or other substances may be added to the cellulose fibres in order to change the properties of the cellulose blank, but air is still used as carrying medium in the forming process.

Advantages with these features are that with the method, a cellulose product can be obtained from a dry formed cellulose blank with the same or even better mechanical properties than in wet formed cellulose products. The term material property substances should be understood as sizing agents, starch and/or other additives that are contributing to the mechanical and chemical features of the cellulose product. The material property substance may for example be added to the cellulose fibres in a dry forming unit during a process of air-laying the loose cellulose fibers in a formation tower and a formation head. Moreover, the adding of the material property substance to the cellulose fibres, might also be understood as the material property substance is sprinkled to a fluff pulp material before the material enters said separating unit. Further, with a dry formed cellulose blank, a cost and energy efficient production method of cellulose products with short cycle times can be achieved, providing a rational production of cellulose products with improved mechanical properties.

When pressing the cellulose fibres with the forming pressure of at least of 4 MPa with a forming temperature in the range of 140°C to 200°C, the cellulose fibres will be strongly bonded to each other, giving the cellulose product desired mechanical properties. Tests have shown that higher forming temperatures will give stronger bonding between the cellulose fibres when being pressed at a specific forming pressure. With forming temperatures above 140°C together with a forming pressure of at least 4 MPa, the cellulose fibres will be strongly bonded to each other. A higher forming temperature will increase the fibril aggregation, water resistance, Young’s modulus and the mechanical properties of the final cellulose product. The high pressure is important for fibril aggregation between the cellulose fibres in the cellulose product. At temperatures higher than 200°C, the cellulose fibres will be thermally degraded and therefore temperatures above 200°C should be avoided.

The cellulose blank may be provided in various forms, for example as a web, a rug, felt, loose fibres, foam, sheets, etc. The cellulose blank may preferably be maid of separate cellulose fibres, e.g. wood fibres from sheet shaped fluff pulp in rolls or fibres from cotton, linen, hemp, sugar cane, or grain, grinded in a separating unit such as a hammer mill. The cellulose blank is air-laid in the dry forming unit comprising the formation tower with the formation head and the cellulose fibres are sucked onto a forming wire. The forming wire may be constructed as an endless continuously moving belt of mesh, using vacuum underneath the forming wire. The air-laid loose cellulose fibres are compacted into a manageable cellulose web by a compacting unit, such as for example calendar rollers. The cellulose web may be pre-heated to a temperature in the range of 40°C to 150°C in the compacting unit.

The term cellulose blank should be understood as any of the refinement stages of the cellulose fibres prior to pressing at a forming temperature in the range of 140°C to 200°C.

According to the disclosure, the cellulose fibres are dry formed into a cellulose blank before heating and pressing the cellulose fibres.

According to a further aspect of the disclosure, the water is added to the cellulose fibres before or during heating and pressing the cellulose fibres. Test have shown that the addition of water may increase the strength of the cellulose product due to the bonding of the cellulose fibres through for example increased fibril aggregation of the cellulose fibres.

According to the disclosure, the one or more material property substances are added to the cellulose fibres in solid phase, and further the one or more material property substances are sprinkled to the cellulose fibres. The one or more material property substances may be added to the cellulose fibres by sprinkling or pouring powder to the cellulose fibres. This can be made in the separating unit or in the dry forming unit wherein the cellulose fibres are already airborne and will therefore evenly mix with the powder. However, the dry formed cellulose blank may be a continuous cellulose web transported on the forming wire, which also can be sprinkled with the powder.

Accordning to a further aspect not of the disclosure, the one or more material property substances are added to the cellulose fibres in liquid and/or vapour phase, where the cellulose fibres may be immersed into the one or more material property substances, or wherein the one or more material property substances are added to the cellulose fibres in liquid and/or vapour phase via rollers, or wherein the one or more material property substances are added to the cellulose fibres in liquid and/or vapour phase through spraying and/or pouring. The one or more material property substances may be sprayed and/or poured onto the cellulose fibres before or during pressing the cellulose blank. The material property substance added in liquid and/or vapor phase will enable water to be added together with dissolved additional substances as for example starch and sizing agents. Adding liquid and/or vapor to the cellulose blank might be understood as the liquid or the vapor is applied to the essentially dry and compressed web of cellulose fibers before or after compressing the loose cellulose fibres into a manageable cellulose web. When adding liquid and/or vapor to the cellulose blank, the continuous cellulose web may be immersed into a hollow container containing the liquid and/or vapor. The advantage with a hollow container containing the liquid and/or vapor this apparatus is the simplicity in applying the material property substance, since the continuously moving forming wire, with the cellulose web, can be deflected by rollers into dipping vats.

According to another aspect not of the disclosure, the one or more material property substances are heated to create the forming temperature of the cellulose fibres. The heating will be an efficient way to establish the forming temperature of the cellulose fibres.

According to an aspect of the disclosure, the one or more material property substances are fed to the cellulose fibres through cavities or channels in a forming mould. In this way, the material property substances may be efficiently fed to the cellulose fibres in the forming process.

According to an aspect not of the disclosure the remaining amount of water is larger than zero when pressing the cellulose fibres. Tests have shown that the addition of water may increase the strength of the cellulose product due to the bonding of the cellulose fibres through for example increased fibril aggregation of the cellulose fibres.

According to a further aspect of the disclosure, the at least one material property substance comprises starch, adding additional functional features to the cellulose product. Through adding starch, the strength of the cellulose product will be increased.

The disclosure further concerns a cellulose product forming apparatus for manufacturing a cellulose product from cellulose fibres, where the cellulose product forming apparatus comprises: an application unit for adding water and/or one or more material property substances; a forming mould for forming the cellulose product; wherein the cellulose product forming apparatus is configured to implement the method described above. An advantage with these features is that with the cellulose product forming apparatus, a cellulose product can be obtained from a dry formed cellulose blank with the same or even better mechanical properties than in wet formed cellulose products.

According to an aspect not of the disclosure, the application unit comprises at least one spray nozzle for applying an aerosol or a vapour of the one or more material property substances on the cellulose fibres prior to or simultaneously with the pressing of the cellulose fibres. The at least one spray nozzle may be integrated as a cavity or a channel in the forming mould.

According to a further aspect not of the disclosure, the application unit comprises at least one applicator roller for applying the one or more material property substances on the cellulose fibres.

According to another aspect not of the dislosure, the application unit comprises at least one container for applying the one or more material property substances on the cellulose fibres.

According to a further aspect of the disclosure, the application unit comprises at least one sprinkle unit for applying the one or more material property substances in powder form on the cellulose fibres.

The disclosure further concerns a cellulose product.

One of the purposes of the present disclosure is to lower the cycle time when producing the cellulose products, and in order to lower the manufacturing cost, pre heating of the cellulose blank might be preferred, e.g. by passing the cellulose blank in a zone of infrared ray heaters. If the cellulose blank is pre heated above the vaporization temperature of the water around 100°C, the cellulose blank might be totally dried from water or other substances when arriving to the forming and pressurizing step. All natural cellulose fibers are hygroscopic and absorb any given humidity from the environment. An air laid cellulose blank is perceived as dry even if it contains ten or more percent of water molecules absorbed from the humidity in the air. By heating, such a dry but water-containing cellulose blank to more than 100°C, all water may vaporize into steam. Steam, with higher temperature than the surrounding air, has the inherent feature of rising to higher heights. I.e. depending on the timing of the heating process and the encapsulation of the cellulose blank, any and all of the naturally present water molecules eventually will have left the cellulose blank at the time of pressurizing the cellulose blank. The absence of water molecules can be overcome by adding extra liquid and/or vapour prior to or simultaneously with the stage of pressing the cellulose blank wherein the remaining amount of liquid and/or vapor, after loss through vaporization, is larger than zero at the time of applying the pressure.

Moreover, according to the present disclosure other and parallel reinforcing processes may be present when the cellulose fibres are heated and pressed, such as creation of hydrogen bonds and the bonding effect of lignin, all contributing to the final strength of the cellulose product.

The inventors have found that the water in liquid and/or vapour phase, at the time of applying heat, in the range of 140°C to 200°C, and pressure above 4 MPa, chemically contributes to the strength of the cellulose product. Said advantage is obtained by the present disclosure wherein said liquid and/or vapour comprise water molecules.

Moreover, the inventors of the present disclosure have found that several additives and/or sizing agents, traditionally used in wet forming of paper products, such as paper and card board, will contribute to the features of the final cellulose product. All cellulose products in daily use comprise some additives or sizing agents to control the features of the material such as for example hydrophobia, wet strength, hardness, tensile strength, Young<'>s modulus, and grease absorption. Fluorochemicals, alkyl ketene dimer (AKD), Alkenyl Succinic Anhydride (ASA), Rosin (Acidic sizing), wax, water glass (sodium silicate) are all examples of sizing agents contributing to less greaseand water absorption, higher mechanical strength and enhancing surface conditions of the finished cellulose products. These additives are normally dispersed in water and added to the pulp in small quantities, normally 1-3 weight percent, before heating and drying. The features less water absorption and higher strength are normally activated by heat. The paper industry adds the additives in the pulp slurry or in sizing presses, such as roll applicators when wet forming flat paper products and cardboard.

Also starch refined from e.g. potatoes, grain or corn, has been found contributing to both mechanical and chemical properties of the final cellulose product. Since the purpose of this disclosure is to replace non-renewable plastics with renewable natural ecofriendly materials, starch may be a preferred alternative. Lignin is another natural substance with binding properties for cellulose fibers. The added material property substances might also contain talc, grinded minerals, or other materials to be used as filler in order to reduce material cost and/or add weight to the cellulose product. Not only the material property substances may be added to the cellulose fibres, but also water, which will contribute to a stronger and more sustainable cellulose product.

According to one embodiment not according to the disclosure, the water with added material property substances may be added in liquid phase to the cellulose blank. Liquid is easy to control via for example a flow controlling valve. The liquid can preferably be preheated to some temperature between 40°C and 90°C. The liquid may contain water with added material property substances and could be sprayed as an aerosol to the cellulose fibres. This method enables a simple zone of spray nozzles to be arranged over the bypassing cellulose blank.

The adding of water and material property substances may, according to an embodiment not according to the disclosure, be applied in vapor phase to the cellulose blank. Vapor has the benefit of being possible to heat to any preferred temperature above 100°C. The steam can then also be used to pre-heat the cellulose blank. On the other hand, steam is volatile and hard to enclose why a method according to the present disclosure wherein said vapor is sprayed to said cellulose blank adjacent or within the forming means of said cellulose blank, is preferred. The closer to the point of forming and pressurization the vapor is added the better control of the added molecule<'>s distribution is obtained. The situation is similar to ironing with steam.

The present disclosure comprises a material property substance applicator comprising: one or several sprinkle units and an essentially dry cellulose blank of cellulose fibers and one or several means to heat said cellulose blank to a forming temperature in the range of 140°C to 200°C, and means to pressing the cellulose blank with a forming pressure of at least of 4 MPa. One example of nozzle is a linear narrow slot with a width equal to the by-passing cellulose blank creating a curtain similar to the established method of painting with curtain coating. The term nozzle should be understood as an outlet for powder. One example of a nozzle is a linear narrow slot with a width equal to the bypassing cellulose blank creating a curtain similar to the established method of painting with curtain coating.

In the cellulose product forming apparatus according the present disclosure, the liquid and/or vapor may be heated to create a forming temperature of the cellulose fibres in the range of 140°C to 200°C and may fulfil two purposes, since the cellulose blank will simultaneously be enriched with the molecules of the substance and heated to the forming temperature.

BRIEF DESCRIPTION OF DRAWINGS These and other aspects of the present disclosure will now be described in more detail, with reference to the appended drawings showing example embodiments of the disclosure, wherein: Fig. 1a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 1b schematically shows a system for dry forming of cellulose products according to the disclosure, Fig. 2a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 2b shows a system in perspective view for dry blow moulding according to the disclosure Fig. 3a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 3b schematically shows a system for dry forming of cellulose products according to the disclosure, Fig. 4a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 4b schematically shows a system for dry forming of cellulose products comprising a container/dipping vat according to the disclosure, Fig. 5a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 5b schematically shows a system for dry forming of cellulose products comprising curtain coating nozzle according to the disclosure, Fig. 6a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 6b schematically shows a system for dry forming of cellulose products comprising two containers according to the disclosure, Fig. 7a schematically shows a block diagram over a method for forming a cellulose product according to the disclosure, Fig. 7b schematically shows a system for dry forming of cellulose products comprising integrated nozzles in the forming mould according to the disclosure, Fig. 8 shows a forming mould with integrated nozzles for blow moulding of cellulose bottles in a perspective view according to the disclosure, and Fig. 9 schematically shows a forming mould made by sintered metal according to the disclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS Fig. 1a schematically shows a block diagram over a method for forming a cellulose product 1 from a dry formed cellulose blank 2 of cellulose fibres 5 in a cellulose product forming apparatus 10, as schematically shown in fig. 1b. According to the method, the cellulose product 1 is formed from the cellulose fibres 5, and the method comprises the steps adding water and/or one or more material property substances 16 to the cellulose fibres 5, heating the cellulose fibres 5 to a forming temperature in the range of 140°C to 200°C, and pressing the cellulose fibres 5 with a forming pressure of at least of 4 MPa. When pressing the cellulose fibres 5 with the forming pressure of at least of 4 MPa with a forming temperature in the range of 140°C to 200°C, the cellulose 5 will be strongly bonded to each other, giving the cellulose product 1 desired mechanical properties. Tests have shown that higher forming temperatures will give stronger bonding between the cellulose fibres 5 when being pressed at a specific forming pressure. With forming temperatures above 140°C together with a forming pressure of at least 4 MPa, the cellulose fibres 5 will be strongly bonded to each other. A higher forming temperature will increase the fibril aggregation, water resistance, Young’s modulus and the mechanical properties of the final cellulose product 1. The high pressure is important for fibril aggregation between the cellulose fibres 5 in the cellulose product. At temperatures higher than 200°C, the cellulose fibres 5 will be thermally degraded and therefore temperatures above 200°C should be avoided. By adding an amount of water to the cellulose fibres 5, the bonding of the cellulose fibres 5 may be even stronger when heating and pressing the cellulose fibres 5. The amount of water added may as an example be up to 10 or even 15 weight percent after vaporization in the heating process so that water is still present in the cellulose blank when the forming pressure is applied. By adding one or more material property substances, the material properties of the cellulose product 1 can be altered in a desired way, e.g. so that the strength and hydrophobic properties are increased.

If not enough water is added, the heating of the cellulose blank 2 to more than 100°C, may result in that all water may vaporize into steam so that any and all of the naturally present water molecules eventually will have left the cellulose blank 2 at the time of pressing the cellulose blank. The absence of water molecules can be overcome by adding extra liquid and/or vapour prior to or simultaneously with the stage of pressing the cellulose blank 2, wherein the remaining amount of liquid and/or vapor, after loss through vaporization, is larger than zero at the time of applying the pressure.

The cellulose fibres 5 may be dry formed into the cellulose blank 2 before the heating and pressing of the cellulose fibres 5 into cellulose products 1. The cellulose blank 2 may be formed from the cellulose fibres 5 in a dry forming unit 11. The dry forming unit 11 may comprises a separating unit 4, a forming wire 6 and a compacting unit 7. The cellulose blank 2 is in the method formed into a cellulose product having a flat or essentially non-flat shape. The cellulose fibres 5 may be provided as cellulose material 14 in rolls, bale or bulk. The cellulose fibres 5 are in the dry forming process separated in the separating unit 4, formed on the forming wire 6, and compacted in the compacting unit 7.

In the separating unit 4, cellulose is separated into detached cellulose fibres 5. The cellulose used in the separating unit 4 may come from any suitable source, such as for example wood pulp and fluff pulp, or cellulose fibres from cotton, linen, hemp, sugar cane and grain. Other types of cellulose material 14 may also be used and depending on the design of the separating unit 4 it may even be possible to re-use cellulose fibres from textiles, paper, cardboard or other suitable sources. As an example, the separating unit 4 may be a conventional hammer mill. Standard virgin fluff pulp may be used as raw cellulose material 14 and can for example be purchased on the open market in rolls. In fig. 1b, a roll of for example fluff pulp is used as raw cellulose material 14, which is fed into the separating unit 4.

The cellulose fibres 5 are arranged onto the forming wire 6 in a conventional way within the dry forming unit 11. The detached cellulose fibres 5 may be drawn from the separating unit 4 by a feeding unit 9, such as for example a centrifugal fan and blown into a formation tower 23 or air carding tower arranged above the forming wire 6. The formation tower 23 comprises a housing with an open bottom providing direct access for the detached cellulose fibres 5 onto the underlying forming wire 6. A vacuum unit 15 may be arranged underneath the upper part of the forming wire 6. The feeding unit 9 is supplying the detached cellulose fibres 5 into the inside of the formation tower 23 and a formation head unit 24 with a number of fibre separating rollers in one or more rows may be arranged in the formation tower housing between the fiber inlet and the formation tower housing bottom to distribute the cellulose fibres 5 evenly onto the forming wire 6. The feeding unit 9 is thus extracting the detached cellulose fibres 5 from the separating unit 4 and is blowing the cellulose fibres 5 into the formation tower 23. The cellulose fibres 5 are drawn by the vacuum in the vacuum unit 15 onto the forming wire 6 in order to form a cellulose web which is further transported by the forming wire 6 to the compacting unit 7. The forming wire 6 may be arranged in a conventional way as an endless belt made for example from a woven mesh structure, which endless belt can be moved continuously with a constant speed when forming the cellulose web. The density of the cellulose web may be chosen so that it is suitable for the cellulose product to be formed.

In order to form the cellulose blank 2 from the cellulose web, the cellulose fibres 5 are compacted or calendared in the compacting unit 7. The compacting unit 7 may be designed with one or more compacting or calendaring rolls integrated within the dry forming unit 11 and the one or more compacting rolls may be arranged together with the forming wire 6. As an example, a compacting roll may be arranged above the forming wire, so that the compacting roll is applying a compacting pressure on the cellulose web formed in the dry forming process. In this way, the cellulose blank 2 is formed as a continuous cellulose web 8 in the dry forming unit 11. The compacting or calendaring rolls may be heated when compacting the cellulose fibres 5.

The dry forming of the cellulose blank 2 is in the embodiment shown in fig. 1b part of a continuous process, in which the cellulose product 1 is manufactured in the cellulose product forming apparatus 10, and the dry forming of the cellulose blank 2 will then be an initial process step before arranging, heating, and pressing the cellulose blank 2 in the forming mould 3.

In order to form the cellulose product 1, the cellulose blank 2 is arranged in the forming mould 3, where the cellulose blank 2 thereafter is heated to a forming temperature in the range of 140°C to 200°C and then pressed in the forming mould 3 with a forming pressure of at least 4 MPa. Tests have shown that suitable pressure levels may be in the range of 4-100 MPa in order to manufacture cellulose products 1 with high quality and strrength. The heating of the cellulose blank 2 may take place before the pressing in the forming mould 3 or at least partly before the pressing in the forming mould 3. As an alternative, the heating of the cellulose blank 2 is taking place in the forming mould 3 when being pressed. The heating of the cellulose blank 2 may for example be accomplished through heating the forming mould 3 before pressing the cellulose blank 2. The pressure may also be applied before heating the cellulose blank 2.

The cellulose blank 2 may be arranged into the forming mould 3 in any suitable way, and the cellulose blank 2 may be transported to the forming mould with the forming wire 6. Another alternative is to arrange a feeding device for the cellulose blank 2, which is transporting the cellulose blank 2 to the forming mould 3. The feeding device could for example be a conveyor belt, an industrial robot, or any other suitable manufacturing equipment. If the dry forming of the cellulose blank 1a is part of a continuous manufacturing process in which the cellulose product is produced, as shown in fig. 1b, the cellulose blank 2 may be intermittently fed to the forming mould 3 by a intermittent feeding unit, not shown in the figures, if the forming wire 6 is moving with a constant speed through the dry forming unit 11 and the forming of the cellulose products in the forming mould 3 is taking place in intermittent process steps.

As described above in relation to fig. 1b, the cellulose product forming apparatus 10 comprises a dry forming unit 11 for forming the cellulose blank 2 and a forming mould 3 for forming the cellulose product. The cellulose product forming apparatus 10 may, as shown in fig. 1b, be constructed as a continuous production unit for cellulose products as one single production unit, in which the cellulose products are manufactured from raw cellulose material 14. The cellulose blank 2 is first formed in the dry forming unit 11 and then formed into a cellulose product 1 in the forming mould 3, where the cellulose product 1 may have a flat or essentially non-flat shape.

The dry forming unit comprises the separating unit 4 for separating cellulose into detached cellulose fibres 5, the formation tower 23 and forming wire 6 for the cellulose fibres 5, and the compacting unit 7 for compacting the cellulose fibres 5 to form a cellulose blank 2. As shown in fig. 1 b, a separately arranged heating unit 12 is heating or pre-heating the cellulose blank 2 before the pressing of the cellulose blank 2 in the forming mould 3. As an alternative, the forming mould 3 may instead be heated by the heating unit, in which a heated fluid medium, an electrical heater, or other suitable heating means is used for the heating of the forming mould 3.

The water and/or one or more material property substances 16 needed in the manufacturing process are applied to the cellulose fibres 5 by one or more application units 13a, 13b. The application units may for example be in the form of one or more spray nozzles 17 or similar devices, which is adding the water and/or one or more material property substances 16 to the cellulose fibres 5 in the dry forming unit 11. The one or more application units may also be arranged at other places within the cellulose product forming apparatus 10 as long as the water and/or one or more material property substances 16 are applied to the cellulose fibres 5.

Fig. 1a shows that the water and/or one or more material property substances 16 are added during the method step of dry forming of the cellulose fibers 5 in the dry forming unit 11, and as shown in fig. 1b, the application units 13a, 13b comprises two spray nozzles 17 in the dry forming unit 11.

According to this embodiment of the invention, the water, in either solid, liquid or vapor form and one or more material property substances 16 in solid form, are ejected into the formation tower 23 of the dry forming unit 11. The separated cellulose fibres 5 are airborne and will be evenly mixed with the water and/or one or more material property substances 16.

The separated cellulose fibers 5 are airborne in the formation tower 23 until they reach the formation head unit 24, which comprises cellulose fibre distributing means such as the fibre separating rollers, brushes and one or several layers of meshes. The forming wire 6 is moving in constant speed over the vacuum unit 15, which may be constructed as a sealed box connected to a vacuum fan. The forming wire 6 is in the embodiment shown in figure 1b essentially an endless mesh structure. The vacuum in the vacuum unit 15 will drag the cellulose fibres 5 down onto the moving forming wire 6, which transports the heap of cellulose fibres 5 together with the added water and/or one or more material property substances 16 out from the formation tower 23 under a first compressing roll 25.

In order to create a manageable continuous cellulose web 8, the cellulose fibres 5 and mixed water and/or one or more material property substances 16 are fed to the compacting unit 7 comprising a second pair of rollers, which may be heated to a temperature in the range of 40°C to 150°C.

The continuous web 8 is pre-heated, preferably to a temperature in the range of 100°C to 200°C, by the heating unit 12, which may comprise infra-red light lamps.

The continuous cellulose web 8 comprising the cellulose fibers 5 and the added water and/or one or more material property substances 16 becomes the cellulose blank 2 in the dry forming unit 11. Intermittent forming of the cellulose blank 2 requires a buffer apparatus for the continuous cellulose web as described above.

The cellulose product forming apparatus 10, may further comprise a hydraulic press and the forming mould, where the parts of the forming mould 3a, 3b may be pre-heated to for example a temperature in the range of 140-200°C, and the final cellulose product 1 will be formed by pressing the heated cellulose blank 2. When pressing the cellulose blank 2, the pressure applied may be at least 4 MPa, and suitably range from 4-100 MPa in order to achieve the desired material properties and strength of the cellulose product 1 when the forming temperature of the cellulose blank 2 is within the temperature range 140-200 °C. In another example, tests have shown that a suitable pressure when pressing the cellulose blank 2 may be 6 MPa when the forming temperature of the cellulose blank 2 is 150°C.

Fig. 2a shows a block diagram where in the process the water and/or one or more material property substances 16 is added according to the embodiment shown in fig. 2b. Fig. 2b shows a complete system in perspective view for dry blow moulding of bottles with two application units 13a, 13b. According to this embodiment, the material property substances 16 can be added in several steps of the method, preferably with different types of molecules. As an example, in a second application unit 13b a powder of starch is sprinkled to the continuous cellulose web 8 in order to increase the mechanical strength of the final cellulose product 1.

Fig. 3a and 3b schematically shows a method for forming of cellulose products 1 from a dry formed cellulose web 2, where the one or more material property substances 16 are fed directly into the separation unit 4 via substance inlet 21. According to this embodiment the one or more material property substances 16 such as starch, calc or vax, which may be in solid phase as granulates or powder, will mix evenly with the cellulose fibers 5 in the separation unit 4. Also water may be added to the cellulose fibres.

Fig. 4a and 4b schematically shows a method for forming of cellulose products 1 from a dry formed cellulose blank 2, comprising a container 20, which may be in the form of a dipping vat. The forming wire 6 and the continuous cellulose web 8 are deflected by rollers into the container 20 containing the water and/or one or more material property substances 16 in liquid or vapor phase. In case of vapor, means for enclosing the vapor, such as a lid with sealed slots for inlet and outlet of said forming wire 6 with continuous cellulose web 8 is preferred but not shown in fig. 4.

Fig. 5a and 5b schematically show a system for forming of cellulose products 1 from a dry formed cellulose blank 2, comprising a nozzle 17 with an outlet slot with a width equal to the width of the rolled sheet of cellulose material 14.

The nozzle 17 is placed above the input path of the cellulose material 14 before the separation unit 4. According to this embodiment not according to the disclosure, the outlet slot creates a curtain of the one or more material property substances 16 in liquid phase that unfolds over the moving surface of the cellulose material 14. This method is similar to the process of curtain coating with paint.

Fig. 6a and 6b schematically shows a system for forming of cellulose products 1 from a dry formed cellulose blank 2 not according to the disclosure comprising two containers 20, where one container is placed above the moving forming wire 6 with the continuous cellulose web 8, and one container is placed underneath the moving forming wire 6 with the continuous cellulose web 8. The containers 20 form an essentially sealed space for hosting an atmosphere of the material property substances 16 in aerosol or vapor form. Nozzles 17 spray the aerosol or vapor into the containers 20 and/or onto the continuous cellulose web 8. This method is similar to the process of spray painting in a spray booth.

Fig. 7a shows in a block diagram the substance to be added within the forming mould 3 according to the method and is further illustrated in fig 8 and 9.

Fig. 7b schematically shows a system for forming of cellulose products 1 from a dry formed cellulose blank 2, comprising integrated channels in the forming mould 3b, wherein the water and/or one or more material property substances 16 are ejected into the cavity of the mould 3, which may occur simultaneously with the closing of the mould 3 when the pressure starts building up in the cellulose blank 2. According to this embodiment the water may be in a preheated vapour phase.

Fig. 8 shows a forming mould 3 with integrated nozzles 17 for blow moulding of cellulose bottles 1 in a perspective view. According to the present disclosure, the pressing of the cellulose blank 2 with a forming pressure of at least of 4 MPa can be obtained by one hollow mould 3b and one bulging mould 3a as shown in fig. 7b, or two hollow mould parts 3 in which closed mould the cellulose blank 2 will be formed and pressurized by a pressure media P supplied by a filling and pressurizing unit 18 inside a sealed and, by a cellulose blank folding unit 19, folded cellulose blank 2 as shown in fig. 8. The latter method is referred to as blow moulding.

According to the present disclosure, regardless of the pressing method of the cellulose blank 2, the moulds 3 can have one or several outlets or nozzles 17 integrated in the cavity surface of the mould, defining the shape of the final cellulose product 1. Fig. 8 shows an example of said cavity surface enlarged for one of the moulds 3 in open state. Several holes or nozzles 17 in the cavity surface are connected to a pressure supply of the water and/or one or more material property substances 16, via a flow controlling device, e.g. a valve, not shown in fig. 8. Even if fig. 8 shows vapor 16 ejected from one nozzle 17 with the mould 3 in open state it is preferred to eject the vapour 16 in all nozzles 17 when the mould 3 is about to close or just has closed around the folded cellulose blank 2.

Fig. 9 schematically shows a hollow forming mould 3 made by sintered metal. Sintered metal made from heated and compressed metal powder or grain of e.g. aluminium, brass or steel is available with different sizes of the material porosity. The purpose of this embodiment is to obtain a semipermeable mould 3 through which the water and/or one or more material property substances 16 can be ejected. The cellulose blank 2 will not penetrate, when pressurized, into the cavities or pores of the surface of the mould 3. According to the embodiment, shown in fig. 9, the mould made by sintered metal can preferably be sealed with a steam shield 22 surrounding all mould surfaces that not should eject vapour. Fig. 9 also shows a supply cavity P, encapsulated by the steam shield 22, in which the vapour is supplied via a flow and pressure device, not shown in fig. 9.

The embodiments according to the present disclosure are not limited to the above examples. Combinations of two or more of the presented methods and apparatuses for adding substance to continuous cellulose web 8 can preferably be used in order to obtain a cellulose product with improved mechanical and chemical properties. Moreover, other methods and apparatuses can be used for adding the water . As an example, one of the rollers in the compacting unit 7 can preferably be used as a roll applicator for the substance 16 in liquid phase.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does 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 measured cannot be used to advantage.

It will be appreciated that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the present disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims. Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand.

REFERENCE SIGNS 1: Cellulose product 2: Cellulose blank 3: Forming mould 4: Separating unit : Cellulose fibres 6: Forming wire 7: Compacting unit 8: Continuous cellulose web 9: Feeding unit : Cellulose product forming apparatus 11: Dry forming unit 12: Heating unit 13: Application unit 14: Cellulose material : Vacuum unit 16: Water and/or material property substances 17: Nozzle 18: Filling and pressurizing unit 19: Cellulose blank folding unit : Container 21: Substance inlet 22: Steam shield 23: Formation tower 24: Formation head unit : First compressing roll

Claims

1. A method for forming an essentially non-flat cellulose product (1), comprising the steps: dry forming cellulose fibres (5) into a cellulose blank (2) in a dry forming unit (11) comprising a separating unit (4), a forming wire (6) and a compacting unit (7); where the cellulose fibres (5) to form the cellulose blank (2) are separated in the separating unit (4), formed on the forming wire (6), and compacted in the compacting unit (7); adding water and one or more additives to the cellulose fibres (5) and/or the cellulose blank (2); forming the cellulose product (1) by heating the cellulose blank (2) to a forming temperature in the range of 140°C to 200°C, and pressing the cellulose blank (2) with a forming pressure of at least 4 MPa, wherein the one or more additives are added to the cellulose fibres (5) and/or the cellulose blank (2) in solid phase, and where the one or more additives are sprinkled to the cellulose fibres (5) and/or the cellulose blank (2).

2. A method for forming a cellulose product (1 ) according to claim 1, wherein the water is added to the cellulose fibres (5) and/or the cellulose blank (2) before or during heating and pressing the cellulose blank (2).

3. A method for forming a cellulose product (1) according to any of the preceding claims, wherein the at least one additive comprises starch, adding additional functional features to the cellulose product.

4. A cellulose product forming apparatus (10) for manufacturing an essentially non-flat cellulose product (1) from cellulose fibres (5), the cellulose product forming apparatus (10) comprising: a dry forming unit (11 ) comprising a separating unit (4), a forming wire (6) and a compacting unit (7), where the cellulose fibres (5) to form a cellulose blank (2) are separated in the separating unit (4), formed on the forming wire (6), and compacted in the compacting unit (7); an application unit (13) for adding water and one or more additives (16), the application unit (13) comprises at least one sprinkle unit for applying the one or more additives in powder form on the cellulose fibres (5) and/or the cellulose blank (2); a forming mould (3) for forming the cellulose product (1), wherein the cellulose product (1) is formed by heating the cellulose blank (2) to a forming temperature in the range of 140°C to 200°C, and pressing the cellulose blank (2) with a forming pressure of at least 4 MPa; characterzedn that the cellulose product forming apparatus (10) is configured to implement the method according to any of claims 1 to 3.

5. A cellulose product (1), characterzedn that the cellulose product (1 ) is manufactured by the method according to any of claims 1 to 3.