Method and apparatus for dry production of rigid cellulosic products

Abstract

An apparatus (100) and method for dry manufacturing of an essentially shaped rigid cellulosic product, the apparatus (100) comprising a disintegrating unit (3), a multi-stage cellulosic blank forming unit (30) and a product forming unit (40) for making a rigid cellulosic product (14). The blank forming unit (30) comprises a dispenser for directing a cellulosic fiber carrying air stream from the disintegrating unit (3), a first forming drum (15) having an outer surface configured to receive the cellulosic fibers and form a part of a cellulosic blank (13) by a first air removal device (54) arranged in the first forming drum (15), a second forming drum (15') for forming a continuous or discontinuous cellulosic blank (13) by a second air removal device (54') arranged in the second forming drum (15), and a support structure (8) for receiving the cellulosic blank (13) formed on said second drum (15').

Description

[Technical field]

[0001] The present invention generally relates to a method and apparatus for the dry production of rigid cellulose products having an essentially non-flat general shape. The cellulose products can be used to package, store, transport, and / or display other products, such as electronics, tools, jewelry, food, dairy products, cosmetics, and / or can be used as single / multiple use disposable articles. The present invention also relates to rigid cellulose products, and continuous or discontinuous cellulose blanks. [Background technology]

[0002] In many situations, it is desirable to provide objects of two-dimensional (2D) or three-dimensional (3D) shape made from sustainable materials. A commonly used material for packaging inserts is wet-molded pulp. Wet-molded pulp has the advantage of being considered a sustainable packaging material because it is made from biomaterials and can be recycled after use. As a result, molded pulp is rapidly gaining popularity in both primary and secondary packaging applications (subsequent packaging of an article and the assembly of such packaging).

[0003] A common drawback of all wet forming techniques is that they require large amounts of water during production and drying of the formed products, which are time and energy consuming processes that slow down production rates and substantially increase investment costs in machinery and tooling, meaning that the technology is not feasible to replace fossil-based alternatives on a large scale.

[0004] Additionally, many modern lean production lines require in-line demand-based packaging or component manufacturing, where wet-forming processes are not preferred or feasible. Recently, new fiber-based materials have been developed with the goal of enabling dry forming of three-dimensional objects / products. One approach is disclosed by WO2014 / 142714, which discloses a dry-laid composite web that is an intermediate product for thermoforming of three-dimensional shaped objects, the dry-laid composite web comprising 40-95% by weight CTMP fibers, 5-50% by weight thermoplastic material, and 0-10% by weight additives, the dry-laid composite web being impregnated with a dispersion, emulsion, or solution containing a thermoplastic material, polymer, and dried to obtain a density of 50-250 kg / m3, or 400-1000 kg / m3 when compressed by calendaring. According to WO2014 / 142714, polymer bonds are activated by the higher temperatures applied in the thermoforming process and contribute to the final strength of the thermoformed object.

[0005] Forming a sheet of cellulose fibers in an air / dry laying process generally weakens the network strength of the cellulose fibers, i.e., weakens their self-supporting properties. The air laid sheet / blank may be an intermediate product in the dry cellulose forming / manufacturing process of an essentially non-flat product. Due to the fragility of the intermediate product, it may be necessary to improve the self-supporting properties of the sheet to improve the efficiency and flexibility of the manufacturing process of the rigid cellulose product with an essentially non-flat overall shape.

[0006] It has been identified that cellulose fibers are very hygroscopic and that the air / dry laying process is sensitive to electrostatic charges as well as process conditions such as air flow and humidity. This behavior of cellulose fibers makes it difficult to provide uniform blanks / sheets of cellulose fibers on the forming structure / web, since the cellulose fibers tend to gather together, resulting in non-uniform / unpredictable basis weight / thickness of the blanks. Attempts have been made in the art to provide a solution to control the properties / basis weight of the cellulose blanks, namely using a tower forming unit as described in SE1750313, where a fiber separating brush and a first compression roller are used in an attempt to obtain a uniform cellulose blank in both the axial and transverse directions. The non-uniform basis weight of the cellulose blanks can be compensated to some extent by an isostatic pressing procedure as described in EP3429928. However, this is more complicated in terms of tooling, requires longer process times and is a more complicated process. The problem with this forming tower and isostatic pressing process is that it is rather complicated, with all of its mechanical components being provided to distribute as uniform a layer of cellulose fibers as possible on the forming web. A common problem with pressing processes to form 3D shaped components / products is that complex component structures / designs and / or products with depth can cause cracks in the cellulose fiber sheets / blanks.

[0007] There is a need in the art for a more reliable dry cellulose forming / manufacturing process for inherently non-flat rigid cellulose products that reduces or eliminates the risk of cracking during the pressing process. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention obviates these and other drawbacks and shortcomings of previously known methods and apparatus for dry producing rigid cellulosic products, and aims to provide an improved method and apparatus for dry producing rigid cellulosic products having an essentially non-flat overall shape.

[0009] The main object of the present invention is to provide an improved method and apparatus for dry forming / manufacturing rigid cellulose products from cellulose fibers having an essentially non-flat overall shape. Another object of the present invention is to provide a method and apparatus for manufacturing rigid cellulose products, which entails that the manufactured cellulose products are free of cracks that would normally result from pressing the cellulose products. Another object of the present invention is to provide a method and apparatus for manufacturing rigid cellulose products, in which the basis weight of the cellulose blanks may be adjusted to obtain a final cellulose product having the required characteristics / properties such as stiffness, thickness, basis weight, etc. Another object of the present invention is to provide a method and apparatus for manufacturing rigid cellulose products, which can produce continuous or discontinuous cellulose blanks. Another object of the present invention is to provide a method and apparatus for manufacturing rigid cellulose products, which generates less debris / waste. Another object of the present invention is to provide a method and apparatus for manufacturing rigid cellulose products, in which the blank forming unit is less complex. [Means for solving the problem]

[0010] According to the invention at least the main object is achieved by a method and an apparatus as defined at the outset having the features defined in the independent claims. Preferred embodiments of the invention are further defined in the dependent claims.

[0011] According to a first aspect of the present invention, - a cracking unit for providing a quantity of separated cellulose fibres from the cellulose feedstock; - a multi-stage cellulose blank forming unit comprising a dispenser for directing a cellulose fibre carrying air stream from the disintegration unit, the multi-stage cellulose blank forming unit being configured to form continuous or discontinuous cellulose blanks having different basis weights at different locations from said quantity of separated cellulose fibres transported by the air stream through the dispenser; - a product-forming unit for producing a rigid cellulose product having an essentially non-flat overall shape from a cellulose blank by pressing; An apparatus comprising: A multi-stage cellulose blank forming unit, - a first forming drum having an outer surface configured to receive cellulose fibers from a dispenser by a first air removal device disposed within the first forming drum and form a portion of a cellulose blank; - a second forming drum having an outer surface configured to receive cellulose fibers from the dispenser and the outer surface of the first forming drum by a second air removal device disposed within the second forming drum and form a continuous or discontinuous cellulose blank; - a support structure for receiving continuous or discontinuous cellulosic blanks formed on said second forming drum; An apparatus is provided, comprising:

[0012] According to a second aspect of the present invention, - providing a quantity of separated cellulose fibers by decomposing a cellulose raw material; - transporting the separated cellulose fibers by an air flow to a multi-stage cellulose blank forming unit having a first forming drum and a second forming drum; - transferring the cellulosic fibers from a first forming drum to a second forming drum; - forming a continuous or discontinuous cellulosic blank having different basis weights at different locations on the outer surface of a second forming drum; - transferring the continuous or discontinuous cellulosic blank from the second forming drum to a support structure; - creating a rigid cellulosic product having an essentially non-flat overall shape by pressing continuous or discontinuous cellulosic blanks having different basis weights at different locations in a product forming unit; A method is provided that includes:

[0013] The present invention is therefore based on the insight that a multi-stage cellulose blank forming unit with two cooperating forming drums to provide a continuous or discontinuous cellulose blank, both forming drums comprising separated cellulose fibres, the cellulose fibres collected on the first forming drum being transferred and connected to the cellulose fibres collected on the second forming drum before the rigid cellulose product is made / pressed. This enhances the ability to adjust the basis weight of different positions of the continuous or discontinuous cellulose blank arriving at the product forming unit compared to a cellulose blank forming unit with only one forming drum. The present invention entails that the continuous or discontinuous cellulose blanks transferred to the support structure may have different / variable basis weights or surface weights in the axial and / or radial directions.

[0014] An advantage of the present invention is that the method and apparatus provide suitable strength and rigidity to the cellulose blank and prevent cracking of the cellulose blank when making / pressing said rigid cellulose product having an essentially non-flat overall shape.

[0015] Another advantage of the present invention is that the basis weight of the cellulosic blank may be easily adjusted to obtain the desired properties of the essentially non-flat rigid cellulosic product to be made. According to various exemplary embodiments of the present invention, the cellulose blanks are discontinuous in the axial and / or transverse directions, i.e. perpendicular and / or parallel to the direction of movement of the support structure / web. The advantage of these embodiments is that individual strips and / or tiles of cellulose blanks may be formed that have sufficient basis weight in the axial and transverse directions for subsequent use in a press tool to make essentially non-flat rigid cellulose products.

[0016] According to various embodiments of the present invention, the outer surface of a first forming drum includes a first area having a first perforation density and a second area having a second perforation density less than the first perforation density to form a sheetlet of cellulose blanks to be transferred to the outer surface of a second forming drum.

[0017] The non-uniform perforation density on the outer surface of the first forming drum provides that different amounts of cellulose fibers adhere / collect on different portions of the rotating first forming drum, such that when the cellulose fibers are transferred from the first forming drum to the second forming drum, the final continuous or discontinuous cellulose blank transferred to the support structure can effectively have different / variable basis weights or surface weights in the axial and / or radial directions.

[0018] According to various embodiments of the invention, the disintegration unit comprises a first disintegration unit configured to provide cellulose fibers to a first forming drum and a second disintegration unit configured to provide cellulose fibers to a second forming drum, whereby the cellulose fibers provided to the first and second forming drums via the dispenser may be of different types, i.e. different raw materials, different fiber sizes, different additives, etc. An advantage of these embodiments is that the mechanical properties of the final cellulose product may be tailored to meet specific requirements.

[0019] According to various embodiments of the present invention, the multi-stage cellulose blank forming unit comprises a compression roll downstream of the second forming drum for compressing the continuous or discontinuous cellulose blank, which is easier to handle in the remaining part of the process, i.e. the individual cellulose fibers are more efficiently locked / entangled with each other before the final pressing.

[0020] Further advantages and features of the present invention will be apparent from the following detailed description of the preferred embodiments. A more complete understanding of the above and other features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of one exemplary embodiment of a continuous cellulosic blank having variable basis weight in the axial and transverse directions. [Diagram 2] 1A and 1B are schematic cross-sectional and top view diagrams, respectively, of one exemplary embodiment of an axially and transversely discontinuous cellulose blank. [Diagram 3] 1 is a schematic diagram of the exterior surface of a forming drum having recesses in the main envelope surface. FIG. [Figure 4] FIG. 1 is a schematic diagram of one exemplary embodiment of an apparatus for dry manufacturing of rigid cellulose products having an essentially non-flat overall shape from cellulose raw materials, in which a cellulose blank is produced by two forming drums. [Diagram 5] FIG. 1 is a schematic diagram of one exemplary embodiment of an apparatus for dry manufacturing of rigid cellulosic products having an essentially non-flat overall shape from cellulosic raw materials, in which different cellulosic raw materials are provided to two separate forming drums. [Figure 6] 1 is a schematic diagram of one exemplary embodiment of an apparatus for dry production of a rigid cellulosic product having an essentially non-flat overall shape from cellulosic raw materials in which the product forming units are successive. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] As used herein, the term "air / dry forming or air / dry laying" refers to the well-known method by which separated cellulose fibers are formed into cellulose blanks / sheets.

[0023] In air laying, small fibers with an average length in the range of 1-50 mm are separated and captured by an air stream / airflow and then laid down / applied to a forming mesh / forming surface, usually using a vacuum / low pressure on the other side of the mesh / surface. The terms "air laying" and "air forming" are used interchangeably herein. The cellulose fiber carrying air stream may be generated by a suitable device located upstream and / or downstream of the forming mesh / forming surface.

[0024] Figures 4, 5 and 6 disclose various exemplary embodiments of an apparatus for dry production of rigid cellulose products according to the present invention for producing cellulose products 14 having an essentially non-flat overall shape from cellulose fibers, the apparatus being generally designated 100. The embodiments of the different figures may be combined.

[0025] The entire apparatus 100 of the present invention is described with reference to FIG. 4, said apparatus 100 comprising a separation / decomposition unit 3, a cellulose blank / sheet forming unit 30 and a final product forming unit 40. A cellulose raw material 1 is fed to the decomposition unit 3. The cellulose raw material 1 may be in the form of a reeled pulp or paper 1a, a bale 1b of cellulose pulp, paper or the like and / or a sheet 1c of paper, cellulose pulp or the like. If said cellulose raw material 1 is in the form of a sheet 1c and / or a reeled pulp or paper 1a, it may be fed directly into the separation unit 3. However, if said cellulose raw material 1 is in the form of a compressed stack of bales 1b or sheets 1c or the like, it may be necessary to use one or more shredders 18 and / or one or more additional separation / decomposition units 3 to separate and inject the cellulose raw material from said bales 1b or sheets 1c in smaller quantities. The shredders 18 prepare the cellulose raw material 1 to be received by said separation unit 3. The separation / decomposition unit 3 decomposes the cellulose raw material 1 into separated cellulose fibres. The one or more shredders 18 are arranged upstream of the one or more separating units 3, and an output of one of the shredders 18 is connected to an input of one of the separating units 3. The shredders 18 may be arranged parallel to one another or perpendicular to one another, and the decomposing units 3 may be arranged parallel to one another or perpendicular to one another. The shredders 18 and the decomposing units 3 together constitute a cellulose fiber separating unit arranged upstream of the cellulose blank forming unit 30.

[0026] The cellulose fibers may be virgin cellulose fibers and / or recycled cellulose fibers and may be derived from wood pulps such as kraft pulp, sulfite pulp, mechanical pulp, thermomechanical pulp (TMP), chemically treated mechanical pulp, chemi-thermomechanical pulp (CTMP), and / or non-wood pulps such as bagasse, bamboo, abaca, hemp, flax, cotton, etc.

[0027] According to various embodiments, the separation unit 3 may be constituted by a hammer mill. In said separation unit 3, the cellulosic raw material is separated into fibers having an average length in the range of 1-50 mm. The length of said fibers may be customized by adjusting the internal characteristics of the separation unit 3 and / or by choosing a different separation unit 3 and / or by choosing a different cellulosic raw material. According to various embodiments, the fiber length of the wood pulp is in the range of 0.5-4 mm, preferably in the range of 1.7-3.6 mm. According to various embodiments, the fiber length of the non-wood pulp is in the range of 0.5-70 mm.

[0028] Generally, in air / dry forming / air laying methods, wood pulp fibers are individualized / separated, for example using a hammer mill, and transported by an air stream through a dispenser that distributes the fibers substantially uniformly across the fabrication apparatus. The fibers are laid down on a moving perforated surface using an air stream generated below the surface by a vacuum / low pressure chamber. As mentioned above, the cellulose fiber carrying air stream may be generated by a suitable device located upstream and / or downstream of the perforated surface.

[0029] 4-6 in particular, which diagrammatically disclose an exemplary embodiment having a multi-stage cellulose blank forming unit 30. It will be pointed out that the upstream and downstream parts of the apparatus 100 described herein can be combined with the multi-stage cellulose blank forming unit 30 shown in FIGS.

[0030] The multi-stage cellulose blank forming unit 30 comprises two sub-steps, i.e. two forming arrangements, which together produce / provide a continuous or discontinuous cellulose blank 13 .

[0031] In FIG. 4, the singulated / separated cellulose fibers are fed to a multi-stage cellulose blank / sheet forming unit 30. In the schematic embodiment according to FIG. 4, the cellulose blank forming unit 30 comprises a first fan 4, a first forming drum / cylinder 15 and a support structure / web 8. The first fan 4 is arranged between the separating unit 3 and the first forming drum / cylinder 15, and the disintegrating unit 3 is connected to the first fan 4. The first fan 4 generates a cellulose fiber carrying air flow and blows the cellulose fibers from the separating unit 3 onto the outer surface of the first forming cylinder 15 via a dispenser extending between the disintegrating unit 3 and the first forming cylinder 15. According to various exemplary embodiments, the application of the fibers onto the first forming cylinder 15 is performed at an angle to the outer surface of the first forming cylinder 15. According to various exemplary embodiments, the angle is 90°, i.e. the fibers are applied perpendicular to the outer surface of the first forming cylinder 15. According to various exemplary embodiments, the angle is less than or greater than 90°, i.e., the cellulose fibers are applied non-orthogonally to the outer surface of the first forming drum / cylinder 15. A predetermined angular interval 5 of the first forming cylinder 15 has a vacuum / low pressure condition. The first forming drum 15 is continuously rotating at a predetermined speed and the angular interval 5 is stationary. Thus, the outer surface of the first forming drum 15 passes through the angular interval 5.

[0032] The separated cellulose fibers may flow at a fiber / air concentration of about 500 g of cellulose fibers per cubic meter of air, the moisture content of the air being 5-20 g water / kg air in the separation unit 3 and / or the cellulose blank forming unit 30.

[0033] The outer surface of the first forming cylinder 15 is perforated. To impart the cellulose fibers containing air onto the outer surface / cylinder of the first forming drum 15, air in the first forming drum 15 is removed at angular intervals 5, and the cellulose fibers remain attached onto the outer surface having perforations, i.e. the cellulose fibers are sucked onto the outer surface of the first forming drum 15. The air is removed by a first air removal device 54 arranged in the first forming drum 15, i.e. at least a part of the first air removal device 54 is arranged in the first forming drum 15. The first air removal device 54 is configured to remove at least the same amount of air as the air introduced by the first fan 4 generating the cellulose fiber carrying air flow. Thereby, the separated cellulose fibers are attached / accumulated on the outer surface of the first forming drum 15 at the positions having perforations. When the cellulose fibers accumulate on the outer surface of the first forming drum 15, the cellulose blank 13 starts to be formed. The amount of cellulose fibers in the air stream from the first fan 4, the speed of the air stream from the first fan 4, the speed of the outer surface of the first forming drum 15, the perforation density of the outer surface, etc. determine the basis weight of the formed cellulose blank 13. Alternatively, the first air removal device 54 may also perform the tasks of the first fan 4, thereby becoming a single device that generates the cellulose fiber carrying air stream to the first forming drum 15.

[0034] Additionally, the multi-stage cellulosic blank forming unit 30 includes a second forming drum 15' that is aligned in all essential respects with the first forming drum 15. As shown in FIG.

[0035] Thus, the second forming drum 15' has an outer surface including perforations, the outer surface being configured to receive cellulose fibers and form cellulose blanks 13 from a quantity of separated cellulose fibers transported by an air flow through a dispenser extending from the outer surface of the first forming drum 15 between the disintegrator unit 3 and the second forming cylinder 15'. Furthermore, a second air removal device 54' is disposed within the second forming drum 15', i.e. at least a portion of the second air removal device 54' is disposed within the second forming drum 15'.

[0036] According to various embodiments, a second fan 4' for generating a cellulose fiber carrying air flow is associated with the second forming drum 15'. A disintegration unit 3 is connected to the second fan 4', a separate disintegration unit or the same disintegration unit acting on the first forming drum 15. The outer surface of the second forming drum 15' is thus configured to receive the cellulose fibers from said amount of separated cellulose fibers transported by the air flow generated by the second fan 4' to form a cellulose blank. Alternatively, one and the same fan may be associated with both the first forming drum 15 and the second forming drum 15'. Alternatively, the second air removal device 54' also performs the tasks of the second fan 4', thereby being a single device generating a cellulose fiber carrying air flow associated with the second forming drum 15'.

[0037] According to the example of FIG. 4, the first forming drum 15 is located upstream of the second forming drum 15', the angular spacing 5' of the second forming drum 15' extends from the position where the cellulose fibers are added from the second fan 4' to the position where the cellulose blank 13 is received by the support structure 8. The second forming drum 15' can produce a continuous cellulose blank on the outer surface of the second forming drum 15', the continuous cellulose blank on the second forming drum 15' can be uniform. A sheetlet of cellulose blank is then added from the first forming drum 15 to the second forming drum 15', after which the cellulose blank 13 having a uniform or variable basis weight is received by the support structure 8. The first forming drum 15 rotates in a clockwise direction and the second forming drum 15' rotates in a counterclockwise direction, the forming drums being located adjacent to each other such that the cellulose fibers of the two drums are in contact at one point / interface.

[0038] According to FIG. 4, the first forming drum 15 forms discontinuous sheetlets of cellulose blanks, i.e. several parts of the cellulose blanks, and the second forming drum 15' also forms discontinuous sheetlets of cellulose blanks. The angular interval 5 of the first forming drum 15 ends at the position / interface where the cellulose fibers of the two drums come into contact, and the angular interval 5' of the second forming drum 15' is active at said position / interface. Thereby, the cellulose fibers of the outer surface of the first forming drum 15 are transferred to the outer surface of the second forming drum 15', and the combined discontinuous cellulose blanks 13 are subsequently received by the support structure 8. FIG. 4 discloses the use of a compression roll 10 located downstream of the two drums and upstream of the product forming unit 40. Under the support structure / web 8, means 54" for removing air are located so that the cellulose blanks 13 produced by the forming drums are fixed to the moving support structure 8. Thereby, the orientation / position of the sheetlets of cellulose blanks 13 is guaranteed. This also applies to the embodiments of the other figures disclosing the device 100.

[0039] The cellulose blank 13 is removed from the second forming drum / cylinder 15' and applied to or received by the support structure / web 8. For that reason, only a predetermined angular interval 5' of the second forming cylinder 15' has the vacuum / low pressure condition. The angular interval 5' overlaps the air flow from the second fan 4. The vacuum condition is released / terminated before the outer surface of the forming cylinder 15 or at the location of the outer surface of the second forming cylinder 15 closest to the support structure 8, thereby allowing the cellulose blank / sheet 13 to be released from the second forming cylinder 15 and applied onto the support structure 8. The support structure 8 may be a continuous web or a continuous belt, as shown in FIG. 1. The rotation / surface speed of the second forming cylinder 15 is synchronized with the speed of the support structure 8. A fan 54 may be provided to create pressure in the forming cylinder 15 at the angular interval 5.

[0040] The support structure 8 may also be a discontinuous web that may be movable back and forth to capture the cellulose blanks / sheets and deliver them to further process steps. The cellulose blanks may be discontinuous, i.e. a stack of multiple sheetlets of cellulose blanks, or continuous, i.e. a folded cellulose blank.

[0041] The cellulose blank 13 is then fed into the product forming unit 40 from within the same production line as the multi-stage cellulose blank forming unit 30 or from intermediate storage between the cellulose blank forming unit 30 and the product forming unit 40. According to various embodiments, the product forming unit 40 comprises a press unit 12 having a shaping tool 11. The shaping tool 11 comprises a male part and a corresponding female part, and includes a design / structure of a final rigid cellulose product having an essentially non-flat overall shape. In FIG. 1, an optional pre-heating unit 16 is arranged upstream of the press unit 12. According to various exemplary embodiments, the cellulose blank 13 may be heated to a high temperature before being fed into the press unit 12 of the product forming unit 40. In such embodiments, in which the cellulose blank 13 is pre-heated before being fed into the press unit 12 of the product forming unit 40, the shaping tool 11 may or may not include heating. According to various exemplary embodiments, the forming tool 11 in the pressing unit 12 may be a heated forming tool 11 for forming the final cellulose product 14 while heating the cellulose blank 13. In the case of a heated forming tool 11, pre-heating of the cellulose blank 13 by the pre-heating unit 16 is optional. According to various exemplary embodiments, pre-heating of the cellulose blank 13 in the pre-heating unit 16 is combined with the heated forming tool 11. In such a case, the cellulose blank 13 may be heated to a first temperature by the pre-heating unit 16, and the forming tool 11 heats the cellulose blank 13 to a second temperature while pressing / forming the final cellulose product 14. The first and second temperatures may be different or equal. According to various exemplary embodiments, pre-heating may be performed to reach an intermediate temperature, which is increased to a final temperature by the forming tool 11. The intermediate temperature may be between the final temperature and room temperature. According to various exemplary embodiments, the intermediate temperature may be close to the final temperature. Having a pre-heating unit 16 in combination with the hot forming tool 11 speeds up the manufacturing process in the press unit 12 .The pre-heating unit 16 may heat the cellulose blank 13 from one side, i.e. the top or bottom, or from both sides, i.e. the top and bottom. The forming tool 11 may heat one or both of the male and female parts and / or the male and female parts may have different temperatures. The optional pre-heating unit 16 may be an IR heater or a resistance heater, with or without a fan.

[0042] In said forming tool 11 said cellulose blank 13 is heated to a temperature of 120-200 ° C to obtain sufficient stiffness and strength in the final cellulose product 14. According to various exemplary embodiments, the cellulose blank 13 may be preheated to 100 ° C before reaching the press unit 12 of the product forming unit 40, in which the cellulose blank is heated to 120-200 ° C by said forming tool 11. According to various exemplary embodiments, the cellulose blank is heated to 120-200 ° C by said preheating unit 16, so that no excess heat is delivered to the cellulose blank during the forming of the final cellulose product 14. According to various exemplary embodiments, the heating of the cellulose blank 13 is only performed in the press unit 12 of the product forming unit 40 during the formation of the final cellulose product 14, i.e. no preheating is performed.

[0043] The apparatus 100 may comprise one or more humidifier units 17a-17b. According to various exemplary embodiments, the first humidifier unit 17a may be arranged to humidify the ambient air at the production site and / or in the internal volume of the apparatus 100 in order to ensure the proper humidity of the cellulose fibers, in particular in the disintegration unit 3 and / or the cellulose blank forming unit 30. According to various exemplary embodiments, the second humidifier 17b may be arranged before the separation / disintegration unit 3, i.e. at the inlet to said separation unit 3, in order to humidify the cellulose raw material entering said separation unit 3. According to various exemplary embodiments, the third humidifier may be arranged at the outlet of said separation unit 3 in order to humidify the cellulose fibers leaving said separation unit 3. The third humidifier may be arranged at the inlet of the first fan 4 and / or the second fan 4' provided for extracting fibrous material from the separation unit 3 and spraying the same fibrous material onto the first forming drum 15 and the second forming drum 15', respectively. A third humidifier may also be positioned at the fan to mix the incoming air with the fibrous material at a desired humidity level prior to application of the cellulosic fibers onto the forming drum. These humidifiers may provide water in liquid and / or gaseous form. Alternatively, in-line humidifiers may be used to provide additives / chemicals other than water in liquid and / or gaseous form.

[0044] The cellulose blank requires a moisture content within a certain range. As mentioned above, the moisture content of the air is 5-20 g water / kg air in the separating unit 3 and / or the cellulose blank forming unit 30. According to various exemplary embodiments, the moisture content of the air is 9-12 g water / kg air in the separating unit 3 and / or the cellulose blank forming unit 30. If the moisture content of the cellulose fibers is too low, it increases the risk of static electricity, which results in uneven formation of the cellulose blank, thereby affecting the basis weight of the cellulose blank. If the moisture content is too high, the cellulose fibers will be clogged, thereby affecting the basis weight of the cellulose blank.

[0045] According to various exemplary embodiments, one or more optional chemical injection units may be provided and configured to increase the network strength of the cellulose blank 13. In a first exemplary embodiment, at least one first chemical injection unit 9 is provided to apply a liquid binder to a bottom surface and / or a top surface of said cellulose blank to form a support layer.

[0046] The liquid binder may only be allowed to have a penetration depth of less than 50% of the thickness in the cellulose blank 13 from either side of the cellulose blank / sheet 13. According to various exemplary embodiments, the penetration depth of the liquid binder is 5-49% of the overall thickness of the cellulose blank 13. According to various exemplary embodiments, the penetration depth of the liquid binder is 10-30% of the overall thickness of the cellulose blank 13. The injection unit 9 may apply the liquid binder before receiving the cellulose blank 13 onto the support web 8. The injection unit 9 may apply the liquid binder before the optional pre-heating unit 16 and / or the pressing unit 12 of the product forming unit 40. The liquid binder may be an organic or inorganic liquid. The final cellulose product 14 is accordingly a laminated product, the different layers of which may have different properties and thicknesses. Increasing the strength and / or stiffness of the final cellulose product 14 may be achieved by adding liquid binders such as starch, vegetable gums, CMC, MFC, synthetic and natural polymers, organic acids, latex, modified cellulose, and / or lignin. The liquid binder does not include thermoplastic resins. The liquid binder may be an organic or inorganic liquid, for example natural polymers or waxes extracted from plants, potassium oxide or magnesium oxide (water glass), silica compounds. The penetration depth may be changed by changing the pressure of the liquid binder in the injection unit 9, and / or by changing the discharge pattern of the injection unit 9, and / or by changing the speed of the cellulose blank 13, and / or by changing the size of the orifice that discharges the liquid binder, and / or by changing the number and / or size of the orifices that discharge the liquid binder, and / or by changing the duty cycle of the discharge of the liquid binder from at least one of the injection units. Also, the viscosity of the additive / agent on the other side of the cellulose blank and / or the degree of compression directly affect the penetration depth.

[0047] The final cellulose product 14 is formed in a press unit 12 of a product forming unit 40. The pressure exerted by the press unit 12 on the forming tool 11 is in the range of 40 to 10000 N / cm 2 According to various exemplary embodiments, the pressure may be in the range of 100 to 4000 N / cm 2 According to various exemplary embodiments, the pressure is 400 N / cm 2 More than 1000 to 3900N / cm 2 It is.

[0048] According to various exemplary embodiments, a liquid or solid agent may be applied onto the cellulosic material prior to the forming / molding step to alter the hydrophobic and / or oleophobic characteristics / properties of the essentially non-flat cellulosic product 14. In FIG. 4, this is illustrated by a second chemical injection unit 2, which applies a liquid agent onto the wound pulp or paper 1a prior to entering the separation unit 3. The liquid or solid agent for altering the hydrophobic and / or oleophobic properties of the essentially non-flat cellulosic product 14 may be a starch compound, a rosin compound, a butane tetracarboxylic acid, a gelatin compound, an alkyl ketene dimer (AKD), an alkenyl succinic anhydride (ASA), a wax compound, a silicon compound, and / or a calcium compound, and may be added as 0.2-15% dry content, preferably 0.5-12% dry content. As explained below, when using parallel decomposition units 3, different chemicals / agents may be applied to the different cellulosic feedstocks 1 fed into the individual decomposition units 3.

[0049] According to various exemplary embodiments, the moisture content of the cellulose blank 13 is at least 5% when the cellulose blank is provided into the forming tool 11. According to various exemplary embodiments, the moisture content of the cellulose blank 13 is 7-12% when the cellulose blank is provided into the forming tool 11.

[0050] The formation of the cellulose blank 13, i.e. the control of the basis weight of the cellulose blank 13, is crucial for the resulting properties of the final cellulose product 14. When the design / structure of the final cellulose product 14 is complex, the prior art solutions do not provide sufficient stiffness / strength to the final cellulose product 14, which leads to cracks during pressing in the forming unit 40. The present invention is based on the insight that the cellulose blank 13 must have different basis weights at different locations so that the final cellulose product 14 has the required properties in terms of stiffness / strength / basis weight and does not exhibit / contain cracks. By having different basis weights at different locations of the cellulose blank 13, the final cellulose product 14 can have a uniform basis weight and / or specified locations and can have a high basis weight.

[0051] To produce / form cellulosic blanks with different basis weights at different locations on the outer surface of the first forming drum 15, the outer surface of the first forming drum 15 comprises a first area with a first perforation density and a second area with a second perforation density less than the first perforation density. Perforation density means the ratio of the open area to the area without openings. The size of the individual perforations may be the same or different throughout the first forming drum 15. Since the first perforation density is higher than the second perforation density, i.e. more air is sucked through the outer surface of the first forming drum 15 in the first area than in the second area, and more cellulosic fibers are attached to the outer surface of the first forming drum 15 in the first area than in the second area. The first forming drum 15 thereby produces a continuous or discontinuous cellulosic blank 13 with a higher basis weight at a first location originating from the first area than at a second location originating from the second area. Higher basis weight means more cellulosic fibers per area of ​​the cellulosic blank 13. The first forming drum 15 may have three or more levels of perforation density and / or the interface between the two areas of different perforation density may be an abrupt or smooth transition.

[0052] According to various embodiments, the second perforation density of the second area of ​​the outer surface of the first forming drum 15 is equal to 0, i.e. there are no perforations, so that the cellulose fibers do not adhere to the second area of ​​the outer surface of the first forming drum 15. Also, the low perforation density of the second perforation density of the second area of ​​the outer surface of the first forming drum 15 entails that a large amount of cellulose fibers do not adhere to the second area of ​​the outer surface of the first forming drum 15. The first and second areas may be provided on the envelope surface of the first forming drum 15. Thereby, a cellulose blank 13 is formed that is discontinuous, i.e. has different basis weights in different locations. Thus, in some locations the basis weight is zero and in other locations the basis weight is high. Each sheetlet of the discontinuous cellulose blank 13 may have a uniform basis weight or areas of different basis weights.

[0053] According to various embodiments, the exterior surface of the first forming drum 15 includes a primary envelope surface 64 and one or more recesses / ingrowths 62 disposed within the primary envelope surface 64 (see FIG. 3). The recesses / ingrowths 62 are suitable for producing a continuous or discontinuous cellulose blank 13 having locations / areas of different basis weight. Thus, a first area of ​​the first forming drum 15 having a first perforation density is located in the one or more recesses 62 to produce a continuous or discontinuous cellulose blank 13 having a higher basis weight at locations originating from the first area than at locations originating from the second area. The locations of the cellulose blank emerging from the ingrowths 62 have a higher basis weight than the locations of the cellulose blank emerging from the peripheral areas of the outer surface of the first forming drum 15 that are free of such ingrowths.

[0054] Each recess 62 may include both a first area having a first perforation density and a second area having a second perforation density and / or the recess may have a different depth relative to the first and second areas. Preferably, the second area having the second perforation density is located in the main envelope surface 64 and the first area having the first perforation density is located within the recess.

[0055] The advantage of having recesses in the forming drum to generate higher basis weight portions of the continuous or discontinuous cellulose blank, i.e. locations with more cellulose fibers, is that the production process of air / dry depositing the cellulose fibers in the forming drum is easier to sort / encapsulate. Furthermore, it is clear that the forming drum may be adapted in various ways to the final cellulose product to reinforce areas that are particularly susceptible to cracking and / or to make certain areas of the product firmer.

[0056] The first forming cylinder 15 may include perforations in the ingrowth area 62 as well as in a main envelope surface 64 surrounding the ingrowth 62 . The above description of the first forming drum 15 also applies to the second forming drum 15'.

[0057] An exemplary embodiment of the resulting continuous cellulose blank 13 provided to the support structure may be similar to that shown in FIG. 1. The lower part of FIG. 1 shows a top view of the cellulose blank 13, and the upper part of FIG. 1 shows a cross-sectional view of the same cellulose blank 13. This cross-sectional view lies in a plane perpendicular to the top surface of the cellulose blank 13 and perpendicular to the movement of the cellulose blank as it is attached to the support structure 8. The cellulose blank 13 exiting the second forming drum 15' may have an essentially flat base structure 34 onto which protrusions of cellulose fibers are attached to form 3D structured cellulose blanks with different basis weights. In FIG. 1, the cellulose blank is a continuous cellulose blank 13 with a 3D structure.

[0058] The non-perforated areas of the forming drum may have a relatively smooth surface. When loose cellulose fibers are resting against such a smooth surface without the possibility of removing excess air, the cellulose fibers have great difficulty adhering to such areas of the forming drum, thereby forming individual sheetlets 32 of the cellulose blank 13 as shown in FIG. 2. FIG. 2 is an example of a discontinuous cellulose blank 13. The sheetlets 32 are shown in FIG. 2 as being separated in both the axial and transverse directions as viewed from above. In alternative embodiments, the sheetlets 32 may be formed into strips / tiles in the axial or transverse directions as viewed from above.

[0059] According to FIG. 4, the product forming unit 40 comprises a fixed press unit 12 with a single forming tool 11 for producing one or more three-dimensional products with a single mold / step. It will be understood that the apparatus according to FIG. 4 may comprise parallel press units 12 and / or parallel forming tools 11 in a single press unit 12. Alternatively, the product forming unit 40 is a continuous process, with female and male parts arranged on two rotary forming units. The rotation of the forming units may be synchronized with the feeding of the cellulose blanks 13 into the product forming unit 40. The rotary forming units may have multiple parallel shapes to form a three-dimensional product. The rotary forming units may include multiple identical shapes to form an identical three-dimensional product. The rotary forming units may include multiple different shapes to form multiple different three-dimensional products. The rotation of the rotary forming units may advance the three-dimensional product from the press unit 12 and feed new cellulose blanks into the press unit 12. It will be pointed out that the product forming units 40 according to the different embodiments are interchangeable without affecting the rest of the apparatus 100.

[0060] The compression roll 10 may compress the air laid cellulose blank 13 to at least one half of its initial / uncompressed thickness. According to various exemplary embodiments, the compression roll 10 compresses the cellulose blank 13 to at least one third of its initial / uncompressed thickness, such that the compressed cellulose blank 13 can be more easily handled after the cellulose blank forming unit 30, i.e., before, up to and within the forming unit 40.

[0061] Thus, each forming drum may produce a continuous cellulose blank as shown in FIG. 1 or a discontinuous cellulose blank as shown in FIG. 2. The result from the first drum is applied to the outer surface of the second forming drum 15'. According to the exemplary embodiment disclosed in FIG. 4, the composition of the cellulose fibers from the first forming drum 15 and the second forming drum 15' is the same, since the cellulose fibers are provided from one and the same separation unit 3. According to an alternative embodiment, as shown in FIG. 5, the first forming drum 15 is fed with separated cellulose fibers from the first disintegration / separation unit, and the second forming drum 15' is fed with separated cellulose fibers from the second disintegration / separation unit. In such a case, as already discussed, the cellulose fibers from the first and second separation units may be different, i.e. originate from different cellulose raw materials, have different fiber lengths, have different agents / additives, and so on.

[0062] Referring now to FIG. 5, it shows the use of a first decomposition unit 3 associated with a first forming drum 15 and a second decomposition unit 3' associated with a second forming drum 15'. In such a case, as already discussed, the cellulose fibers from the first decomposition unit 3 and the second decomposition unit 3' may be different in order to further tailor the properties of the final cellulose product 14. It will be pointed out that when different decomposition units are associated with different forming drums / units, these decomposition units may also be configured to provide the same type of cellulose fibers. Different layers of the cellulose blank 13 may have different properties due to different additives / agents being added to the different cellulose raw materials, which allows for very precise control of the penetration depth of the additives in the final cellulose product 14.

[0063] 6, the cellulose blank forming unit 30 comprises an alternative type of compression roll 10. The compression roll 10 is also configured to remove and transfer the continuous or discontinuous cellulose blanks 13 from the second forming drum 15' to the support structure 8 at the same time as the cellulose blanks 13 are compressed.

[0064] Thus, the compression roll 10 is constituted by one or more compression drums, on the inside of each of which the perforation and air removal means are arranged. Thereby, the cellulose blank 13 formed on the second forming drum 15' is transferred to the first compression drum at the position / interface where the angular interface 5' of the second forming drum 15' ends and the corresponding angular interface of the first compression drum becomes active. The transfer from one drum to another is the same throughout the device 100, i.e. one angular interval ends (pressing is ended) and the next angular interval becomes active (pressing is active). The second compression drum is located close to the first compression drum and at the position / interface where these compression drums meet, the continuous or discontinuous cellulose blank 13 is compressed and transferred from the first compression drum to the second compression drum. The compressed cellulose blank may be transferred to an additional compression drum before it is received by the support structure 8, during such additional transfer the cellulose blank may be further compressed.

[0065] According to an alternative embodiment, the second compression drum is replaced by a compression roll and the cellulose blank 13 is compressed between the first compression drum and such compression roll, without the cellulose blank being transferred from the first compression drum. The compressed cellulose blank is then transferred from the first compression drum to the support structure 8.

[0066] According to various exemplary embodiments, an intermediate product for dry production of at least one rigid cellulose product 14 having an essentially non-flat overall shape may be produced. Said intermediate product is constituted by continuous or discontinuous cellulose blanks 13 having different basis weights at different positions, i.e. a first position and a second position, the first position having a higher basis weight than the second position. The basis weight at the second position may be, as discussed above, 0, etc. Such an intermediate product may be provided, for example, in the form of individual sheets or on a roll. The first position of the cellulose blank, i.e. the intermediate product, overlaps an area susceptible to cracking and / or an area of ​​increased stiffness of the subsequent rigid cellulose product 14 having an essentially non-flat overall shape.

[0067] From the intermediate product, i.e. the cellulose blank 13, a rigid cellulose product 14 having an essentially non-flat overall shape may be produced by pressing in a product forming unit 40, the maximum basis weight of the rigid cellulose product 14 being smaller than the maximum basis weight of the continuous or discontinuous cellulose blank 13. Thus, the cellulose fibers of the cellulose blank 13, the intermediate product, are again dispersed during the pressing step in response to the non-flat overall shape of the final cellulose product 14.

[0068] The circumferential speed in the separation unit may be in the range of 50-150 m / s. In various exemplary embodiments, said circumferential speed may be in the range of 90-150 m / s. In various exemplary embodiments, the size of the cellulose fibers may be 2 mm and the amount of fibers per unit volume of air may be 100 g of fibers / m3 of air at 9-12 g water / kg of air. The support structure, the continuous forming cylinder, and / or the continuous web may have a width of 20-100 cm. In various exemplary embodiments, said width is 30-70 cm. The sheet of cellulose fibers 13 may have a weight of 200-2000 g / m2. The pressure in the pressure unit may be in the range of 40-10000 N / cm2.

[0069] According to one example, discontinuous cellulose blanks are formed on the outer surface of the second forming drum 15', each sheetlet being approximately 20 cm x 30 cm. To obtain a final cellulose product with a thickness of 0.5 mm, the basis weight is approximately 600 g / m2 in the first area and 0 g / m2 in the second area, i.e. between the sheetlets of discontinuous cellulose blanks. This process can produce 2500 sheetlets per hour, each sheetlet weighing 36 g, i.e. 90 kg of cellulose raw material per hour. To obtain approximately 500 g of cellulose fibres per cubic metre of air, the required air flow is 180 m3 of air per hour. To accumulate sufficient cellulose fibres for each sheetlet of cellulose blanks, the air velocity at the outer surface of the second forming drum 15' is approximately 3-5 m / s.

[0070] The humidity of the air stream should be in the range of 9-12 g / kg air, preferably 11 g / kg air (equal to 14.3 g / m3 air). Depending on the humidity of the surrounding air, different amounts of water must be added to obtain the required level. The humidity of the surrounding air should preferably be in the range of 55-65% RH at 20 degrees Celsius.

[0071] According to one example, two forming drums 15, 15' are used to form discontinuous cellulose blanks. A first circular cellulose blank is formed on the outer surface of the second forming drum 15', with a diameter of 40 cm and a basis weight of about 500 g / m2, and a second circular cellulose blank is formed on the outer surface of the first forming drum 15', with a diameter of 20 cm and a basis weight of about 200 g / m2. This process can produce 2500 sheetlets per hour, each sheetlet weighing 63+6=69 g, i.e. 172.5 kg of cellulose raw material per hour. To obtain about 500 g of cellulose fibre per cubic meter of air, the required air flow is 345 m3 of air per hour.

[0072] Possible modifications of the present invention The present invention is not limited to the above-mentioned embodiment described in the drawings, which are mainly for the purpose of explanation and illustration. This patent application is intended to cover all adjustments and variations of the preferred embodiment described herein, and the present invention is therefore defined by the expressions of the appended claims and their equivalents. Thus, the device may be modified in any manner within the scope of the appended claims. Throughout this specification and the claims which follow, unless the context otherwise requires, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or step or group of integers or steps rather than the exclusion of any other integer or step or group of integers or steps.

[0073] It is therefore also pointed out that even when it is not explicitly stated that features from a particular illustrated embodiment may be combined with features from another embodiment, where such a combination is possible, the combination shall be considered as obvious.

Claims

1. An apparatus (100) for dry manufacturing a rigid cellulosic product (14) having an essentially non-flat overall shape, comprising: a decomposition unit (3) for providing a quantity of separated cellulose fibres (6) from the cellulose raw material (1); a multi-stage cellulose blank forming unit (30) comprising a dispenser for directing a cellulose fibre carrying air stream from said disintegration unit (3), configured to form continuous or discontinuous cellulose blanks (13) having different basis weights at different locations from said quantity of separated cellulose fibres transported by said air stream through said dispenser; a product-forming unit (40) for producing, by pressing, a rigid cellulose product (14) having an essentially non-flat overall shape from said cellulose blank (13); An apparatus (100) comprising: The multi-stage cellulose blank forming unit (30) a first forming drum (15) having an outer surface adapted to receive cellulose fibres coming from said dispenser and to form part of said cellulose blank (13) by means of a first air removal device (54) arranged within said first forming drum (15); a second forming drum (15') having an outer surface adapted to receive cellulose fibres coming from said dispenser and said outer surface of said first forming drum (15) and to form said continuous or discontinuous cellulose blank (13) by means of a second air removal device (54') arranged within said second forming drum (15); a support structure (8) for receiving said continuous or discontinuous cellulose blank (13) formed on said second forming drum (15'); An apparatus (100), comprising:

2. 2. The apparatus (100) of claim 1, wherein the outer surface of the first forming drum (15) includes a first area having a first perforation density and a second area having a second perforation density less than the first perforation density to form a sheetlet of cellulose blanks (13) to be transferred to the outer surface of the second forming drum (15').

3. The dispenser of the multi-stage cellulose blank forming unit (30) a first fan (4) for generating a cellulose fibre carrying air flow directed towards said first forming drum (15), and / or a second fan (4') for generating a cellulose fibre carrying air stream directed towards said second forming drum (15'); The apparatus (100) of claim 1 or 2, comprising:

4. 4. The apparatus (100) according to any one of claims 1 to 3, wherein the disintegration units comprise a first disintegration unit (3) configured to provide cellulose fibres to the first forming drum (15) and a second disintegration unit (3') configured to provide cellulose fibres to the second forming drum (15).

5. 5. The apparatus (100) according to any one of claims 1 to 4, wherein the product forming unit (40) comprises a shaping tool (11) for producing the rigid cellulose product having an essentially non-flat overall shape from the continuous or discontinuous cellulose blank (13).

6. The apparatus (100) according to any one of claims 1 to 5, wherein the multi-stage cellulose blank forming unit (30) comprises a compression roll (10) downstream of the second forming drum (15') for compressing the continuous or discontinuous cellulose blank (13).

7. The apparatus (100) according to claim 6, wherein the compression roll (10) is also configured to remove the continuous or discontinuous cellulose blank (13) from the second forming drum (15') and transfer the cellulose blank (13) to the support structure (8).

8. 1. A method for dry producing a rigid cellulosic product (14) having an essentially non-flat overall shape, comprising: - providing a quantity of separated cellulose fibres (6) by decomposing a cellulose raw material (1); - transporting said separated cellulose fibres (6) by an air stream to a multi-stage cellulose blank forming unit (30) having a first forming drum (15) and a second forming drum (15'); - transferring said cellulose fibres from said first forming drum (15) to said second forming drum (15'); - forming on the outer surface of said second forming drum (15') a continuous or discontinuous cellulosic blank (13) having different basis weights at different locations; - transferring said continuous or discontinuous cellulose blank (13) from said second forming drum (15') to a support structure (8); - creating a rigid cellulosic product (14) having an essentially non-flat overall shape by pressing said continuous or discontinuous cellulosic blank (13) having different basis weights at different locations in a product forming unit (40); A method comprising:

9. 9. The method according to claim 8, wherein the continuous or discontinuous cellulosic blank (13) is compressed downstream of the second forming drum (15').

10. A continuous or discontinuous cellulose blank (13) which is an intermediate product for the dry production of at least one rigid cellulose product (14) having an essentially non-flat overall shape, said continuous or discontinuous cellulose blank (13) having different basis weights at different locations.

11. 11. A rigid cellulose product (14) having an essentially non-flat overall shape, produced by pressing the continuous or discontinuous cellulose blank (13) of claim 10 in a product forming unit (40), the maximum basis weight of the rigid cellulose product (14) being less than the maximum basis weight of the continuous or discontinuous cellulose blank (13).

12. 12. The rigid cellulose product (14) having an essentially non-flat overall shape according to claim 11, wherein the cellulose product (14) comprises cellulose fibers from a cellulose raw material (1) constituted by virgin cellulose fibers and / or recycled cellulose fibers, the cellulose fibers being derived from wood pulps such as kraft pulp, sulfite pulp, mechanical pulp, thermomechanical pulp, chemically treated mechanical pulp, chemi-thermomechanical pulp, and / or non-wood pulps such as bagasse, bamboo, abaca, hemp, flax, cotton, and the like.

Images