Method and device for producing a microfibrillated cellulose film

Abstract

A method for manufacturing an MFC film from a microfibrillated cellulose (MFC) dispersion, comprising subjecting a wet MFC film (F) on a support to at least one drying step to form a dried MFC film (F'), and measuring at least one parameter indicative of the concentration of at least one component such as an additive or an impurity. i) a task of adjusting at least one manufacturing parameter that affects the concentration of the at least one component according to the at least one parameter, and ii) a task of providing a chemical map of the dried MFC film (F') including a plurality of data points each associated with a respective position on the dried MFC film (F'), by recording the at least one parameter for each of the data points. performing at least one of the above A method comprising the above.

Description

Technical Field

[0001] The present invention relates to microfibrillated cellulose, MFC, methods and devices for manufacturing films. The present disclosure particularly relates to methods capable of providing high-quality MFC films that can minimize variations in the content of additives and / or at least identify and manage impurities. The present disclosure further relates to devices for manufacturing such MFC films and the use of such devices for manufacturing MFC films. The present invention also relates to MFC films manufactured according to this method.

[0002] Such methods and devices are particularly found in specific applications in the continuous production of MFC films.

Background Art

[0003] In the context of the present application, microfibrillated cellulose (“MFC”) is defined as having cellulose particles, fibers or fibrils with a width or diameter of 20 nm to 1000 nm.

[0004] To produce MFC, there are various methods such as single or multiple pass refining, pre-hydrolysis, followed by various means like refining, high-shear fibrillation or fibrillation release. To realize MFC production from both the perspectives of energy efficiency and sustainability, usually one or more pre-treatment procedures are required. Thus, the cellulose fibers of the pulp used for MFC production can be natural or, for example, enzymatically or chemically pre-treated to reduce the amount of hemicellulose or lignin. The cellulose fibers can be chemically modified prior to fibrillation, in which case the cellulose molecules contain functional groups other than (or more than) those found in the original cellulose. Such groups include, inter alia, carboxymethyl (CM), aldehyde and / or carboxyl groups (cellulose obtained by N-oxyl mediated oxidation, e.g. "TEMPO"), or quaternary ammonium (cationic cellulose). After modification or oxidation by any of the above methods, the fibers are ready to be broken down into MFC.

[0005] MFC can be produced from softwood and / or hardwood wood cellulose fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. For example, it can be produced from pulp containing virgin fibers such as mechanical pulp, chemical pulp and / or thermomechanical pulp. It can also be made from waste paper or recycled paper, or similar packaging substrates.

[0006] Current research indicates that MFC may be a suitable material for packaging and packaging coatings due to its barrier properties. Thus, MFC has the potential to replace or complement currently used barrier films and layers, including polymer and metal films and coatings.

[0007] The formation of MFC films can be achieved by solvent casting a viscous or gel-like fluid material onto a support such as a continuous conveyor belt, followed by dehydration / drying (e.g., evaporation) of the solvent.

[0008] The term "solvent casting" refers to a known method by which a film is produced by applying a wet film containing film-forming components dispersed in a medium that is essentially removed by, for example, dehydration and / or evaporation. The film-forming components are either dispersed in the dispersion medium or dissolved in a solvent, thus being called "solvent casting".

[0009] Hereinafter, the term "MFC dispersion" is used to refer to a dispersion / suspension or solution containing MFC and a dispersion medium (usually water). The MFC dispersion becomes viscous.

[0010] The use of MFC films in packaging applications involves certain challenges due to the brittleness of the MFC films. The elasticity and ductility of the MFC films are related to the moisture present in the MFC films, and the MFC films become brittle when they are too dry. Drying and the associated brittleness can potentially have a local impact on the MFC films, especially on the edge regions of the films. In the casting process, the side edges of the MFC films tend to dry faster than the central part of the film, resulting in a difference in moisture content and ductility in the machine direction (MD), and accordingly, the edges become brittle. Furthermore, non-uniform drying can lead to a non-uniform distribution of additives within the film. MFC films tend to break easily during the conversion process, especially due to their brittle edge portions. This problem is not necessarily limited to the narrow and slow operations seen in laboratory and pilot-scale manufacturing processes and the use of films, but becomes even more significant when operating film production on wider machines and / or in large-scale and faster production.

[0011] Known approaches use plasticizers and / or humectants such as sugar alcohols (e.g., sorbitol) or polyethylene glycol to make the MFC film more ductile. However, such hygroscopic additives and the water bound to the film interfere with the binding of microfibrils, increase the strain value at break, and decrease the tensile strength. The use of such additives improves the overall level of ductility of the film, but the film remains too brittle, leaving problems regarding changes in the moisture content of the film in the machine width direction and brittle edges as well.

[0012] A further problem relates to the manufacture of MFC films by casting techniques when film drying from the top of the film, infrared (IR), or other thermal drying is used to dry the film on a non-porous casting support. The casting support needs to be slightly wider in the machine width direction than the wet MFC film deposited thereon. However, due to the heat flux applied from above, the temperature of the casting support edges without the wet MFC layer on them increases, so the side edge portions of the film are exposed to additional heat. This additional heat at the edges of the casting support causes the MFC film to dry faster at the edges. Since the MFC film is very thin, it easily dries out excessively.

[0013] Furthermore, if the MFC film can have a non-uniform moisture or additive profile within the CD, the peel behavior or adhesion of the dry or semi-wet MFC film to the casting support changes and becomes unpredictable or has greater variability. Since the edges of the film dry faster than the center, the edges tend to lose adhesion to the casting support earlier. This results in deformation or damage to the edges of the MFC film and breakage of the web in the manufacture of MFC films. In the manufacture of MFC films, one or more property-modifying additives can be added to the MFC dispersion. Non-limiting examples of such additives include softening agents, film-forming agents, additives that promote barrier and / or extensibility properties, and the like.

[0014] Furthermore, in the production of the MFC film, it is desirable to increase the dry solid content in the device that applies the MFC dispersion to the support, because this reduces the amount of the dispersion medium removed and facilitates the drying process.

[0015] However, when the dry solid content increases, the viscosity of the MFC dispersion increases, so the risk of the additive being unevenly dispersed in the MFC dispersion increases. On the other hand, if the MFC dispersion is mixed too much, fiber aggregation is likely to occur and / or energy may be consumed. Therefore, it is important to control the mixing according to the process data.

[0016] The elevated temperature can be used to reduce the viscosity of the MFC dispersion and thus facilitate mixing. Furthermore, controlling the pH or conductivity of the MFC dispersion will be necessary to achieve uniform additive dispersion.

[0017] The challenges in the subsequent drying of the MFC dispersion are that the dehydration and drying processes cause in-plane and out-of-plane movement of the dispersion medium in the wet film, and the migration of additives in the film after application on the support, especially additives that dissolve in the dispersion medium and / or additives that do not easily adhere to the MFC fibers.

[0018] Such migration can affect various film properties such as runnability, barrier properties, and / or mechanical performance.

[0019] Therefore, improvement is needed when converting the MFC dispersion into an MFC film on the support. Also, further improvement is needed regarding the properties of the MFC film, especially the uniformity of the MFC film properties across the entire MFC film. SUMMARY OF THE INVENTION

[0020] The aim is to provide a method and system for improving the quality of MFC films while minimizing or even reducing the manufacturing cost without increasing it. The specific aim is to address issues related to non-uniform film properties such as barrier properties and local brittleness, and / or running properties in film manufacturing and conversion.

[0021] The present invention is defined by the appended independent claims, and embodiments are described in the appended dependent claims, the following description, and the appended drawings.

[0022] According to a first aspect, a method for manufacturing an MFC film from a microfibrillated cellulose (MFC) dispersion is provided. The method includes providing an MFC dispersion including a dispersion medium and a film-forming component including about 50 to 100 wt% of MFC, applying a layer of the MFC dispersion to a support to form a wet MFC film, subjecting the wet MFC film on the support to at least one drying step to form a dry MFC film, and measuring at least one parameter indicative of the concentration of at least one component, such as an additive or an impurity, in the wet MFC film and / or the dry MFC film at at least two data points spaced laterally across the width of the MFC film and / or longitudinally along the length of the MFC film. The method further includes i) the task of adjusting at least one manufacturing parameter that affects the concentration of the at least one component in the MFC film according to the at least one parameter, and ii) the task of recording the at least one parameter for each of the data points to provide a chemical map of the dry MFC film including a plurality of data points respectively associated with respective positions on the dry MFC film and performing at least one of including.

[0023] The content of the dispersion medium in the MFC dispersion may be at least 75% by weight, preferably more than 80% by weight, more than 85% by weight, more than 90% by weight, or more than 95% by weight. The film-forming component comprises MFC, consists of MFC, or is essentially composed of MFC, and optionally may be accompanied by one or more water-soluble polymers that can function as co-additives and / or co-film-forming agents. Thus, the MFC dispersion contains a dispersion medium and a film-forming component, and the film-forming component contains 50 to 100% by weight of MFC (i.e., based on the total dry weight of the film-forming component). For example, in addition to MFC, the film-forming component can contain a water-soluble polymer that can form a film and / or improve the bonding between cellulose fibers. Typical examples of such polymers are, for example, natural gums or polysaccharides or their derivatives, such as carboxymethyl cellulose (CMC), starch, or PVOH or their analogs. The film-forming component may also contain one or more additional additives such as one or more property-modifying additives. Non-limiting examples of such additives / chemicals are softeners and plasticizers such as glycols, sugar alcohols such as sorbitol, polysaccharides such as sorbitol and glucose, polyvinyl alcohol (PVOH), film-forming agents such as carboxymethyl cellulose or methyl cellulose, fillers, pigments, retention chemicals and dispersants or other polyelectrolytes, latexes, cross-linking agents, optical dyes, fluorescent whitening agents, defoaming chemicals, salts, pH-adjusting chemicals, surfactants, biocides, and / or optical chemicals. The film-forming component may also contain other natural fiber materials in addition to MFC.

[0024] The layer of the MFC dispersion can be applied to a substrate by a casting technique.

[0025] The support may be a non-porous support, particularly a continuous non-porous support such as a metal belt, particularly a steel belt, a polymer belt, or a polymer-coated belt. The metal belt can be coated, for example, with a ceramic material.

[0026] The dispersion medium can include water and optionally one or more solvents.

[0027] By measuring a parameter indicating the concentration of at least one component such as an additive or an impurity present in the MFC dispersion at at least two spaced-apart data points in at least one of the width direction and the length direction of the MFC film, it is possible to identify changes in the component content along the entire width and / or length of the film.

[0028] For example, a component (which may also be referred to as a constituent) can be a compound, an atom, or an ion.

[0029] The component can be an additive intentionally added to modify the properties of the wet film or the dry film. Alternatively, the component can be an impurity, which can originate from any location upstream of the point where the measurement is taken.

[0030] The parameter to be measured may be, as a non-limiting example, a spectroscopic response that can directly indicate the presence and concentration of the component. As yet another example, the parameter may be, for example, a temperature that indirectly indicates the presence or absence of a component correlated with the content of the dispersion medium.

[0031] Such changes may only become visible after the MFC film has been dehydrated and / or at least partially dried.

[0032] The measurement can be carried out substantially continuously during the production of the MFC film.

[0033] Based on the identification of such changes, appropriate measures can be taken to adjust at least one production parameter to ensure a uniform distribution of the components within the MFC film.

[0034] The manufacturing parameters may be, by way of non-limiting example, the drying conditions of the MFC film, the dehydration conditions of the MFC film, the mixing conditions of the MFC dispersion or the application conditions of the MFC dispersion. The manufacturing parameters may also be the amounts of MFC, dispersion medium and / or components provided to the MFC dispersion, and the points and / or times within the process at which they are added.

[0035] It is also possible to generate a chemical map of the MFC film. Such a map may be provided as a 2D map of the dried MFC film where only 2D data is measured, or may be provided as a 3D map where data in the thickness direction of the MFC film is also collected.

[0036] The 2D map provides data regarding the MFC film within the plane formed by the width direction (machine width direction) and the length direction (machine direction or length direction) of the MFC film. The 3D map also includes data in the thickness direction (z-direction) of the MFC film.

[0037] The map shows how the concentration of one or more components varies across the entire MFC film. The map can be utilized for downstream processing of the film. For example, regions or portions of the MFC film where the content of a component is too high, as seen in the length direction, can be removed from the dried MFC film, for example, from a roll of the dried MFC film, according to the 2D map of the film. As another example, slitting of the edges can be planned and controlled according to the 2D map, and for example, a wide area near the side edges can be removed if the distribution of the constituent components is non-uniform near the side edges.

[0038] The dried film can be considered as a material formed in a thin continuous sheet shape. Depending on its composition, purpose, and properties, the dried film can be regarded as thin paper or web, or even as a membrane.

[0039] In actual embodiments, a large number of data points are provided, thereby making it possible to derive a detailed profile of the content of the components of the film.

[0040] The measurement step may be performed after at least a part of the at least one drying step.

[0041] Therefore, the measurement can be performed after one or more drying steps, such as after the entire drying process, or can also be performed between the drying steps.

[0042] The method further includes at least one dehydration step before the at least one drying step, and the measuring step is performed after at least a part of the at least one dehydration step and before the at least one drying step.

[0043] Therefore, the measurement can be performed after one or more dehydration steps, such as after the entire dehydration process, before the drying step, or between sub-steps of the dehydration process.

[0044] Measurement can also be performed after peeling the dry film from the support. Next, the measurement is performed on the upper surface and / or the back surface of the film.

[0045] The method further includes a preliminary drying step performed before the at least one dehydration step, and the measurement step is performed after the preliminary drying step and before the at least one dehydration step.

[0046] Adjusting at least one manufacturing parameter may include changing the drying conditions and / or changing the dehydration conditions.

[0047] Changing the drying conditions to affect drying means that the moisture content is affected, and thereby the concentration of the components dissolved in the dispersion medium is affected. The drying conditions can vary across the entire width or a part of the MFC film on the support.

[0048] In the dehydration section, it is possible to change the alignment and / or relative angle between the press nip and / or the press roll.

[0049] It is also possible to change the press felt, for example, to provide press felts with different characteristics and / or to replace a contaminated press felt.

[0050] Changing the drying conditions may include reducing the drying effect on at least one side edge portion of the wet MFC film.

[0051] The side edge portion can be defined as a region extending 50 mm, preferably 30 mm or 10 mm, in a direction perpendicular to the longitudinal direction (parallel to the length direction MD) of the MFC film from the outermost edge (side edge) of the MFC film.

[0052] Changing the drying conditions may include guiding the drying gas away from at least one side edge portion of the MFC film.

[0053] Changing the drying conditions may include extracting the drying gas from at least one side edge portion of the MFC film.

[0054] Changing the drying conditions may include, for example, masking the side edge portion of the MFC film from the drying gas and / or radiation.

[0055] Changing the drying conditions may include sealing against the support surface outside the lateral direction of the side edge portion of the MFC film.

[0056] Accordingly, the heating of the support is reduced, and the drying effect at the edge portions of the films (F, F') is reduced.

[0057] Another example of changing the drying conditions is to control the temperature profile of the support heated or cooled from below.

[0058] Varying the drying conditions may include selectively controlling the duty cycle, combustion gas pressure, and / or the intensity of the radiation source for drying.

[0059] Varying the drying conditions may include selectively injecting at least one of a cooling medium and a dispersion medium onto the wet MFC film.

[0060] Water can be used as the cooling medium and / or the dispersion medium.

[0061] Varying the drying conditions includes laterally cooling at least one support edge outside the wet MFC film by applying a cooling medium.

[0062] Changing the drying conditions may include applying the cooling medium to the side edge portion of the MFC film and / or applying the dispersion medium to the side edge portion of the MFC film.

[0063] The method further includes separating the dried MFC film from the support and winding the separated MFC film onto a reel.

[0064] Thus, the MFC film remains on the support throughout the entire drying process (and the entire dehydration process if there is a dehydration process).

[0065] Adjusting the at least one manufacturing parameter may include adjusting the dosage of the at least one component.

[0066] The dosage can be adjusted by reducing or increasing the supply of one or more components. It is also conceivable to supply additional components to supplement other components.

[0067] The dosage can be adjusted upstream of applying the layer of the MFC dispersion to the support, such as in the MFC supply section.

[0068] The dosage can be adjusted in a device for applying the MFC dispersion layer to the support.

[0069] Adjusting at least one manufacturing parameter can include adjusting the mixing conditions of the MFC dispersion.

[0070] The manufacturing parameters are the mixing speed, mixing time, and / or the duty cycle of the mixer. Optionally, it is also possible to operate one or more individually drivable mixing devices.

[0071] The manufacturing parameters may also be related to the supply of components in that the supply position of the components can vary along the flow direction towards the casting device for applying the layer of the MFC dispersion to the support or across the width of the casting device.

[0072] Furthermore, after applying the MFC dispersion to the support, it is also possible to selectively supply components to the surface of the wet MFC film.

[0073] The manufacturing parameters may be, for example, the temperature within the MFC supply, casting device, and / or drying device.

[0074] The production parameters may be, for example, the delay time between the MFC supply and the casting device.

[0075] The manufacturing parameters may be, for example, the level within the MFC supply and / or casting device (i.e., the amount of MFC dispersion present).

[0076] It is also possible to adjust the supply of the MFC itself and / or the dispersion medium.

[0077] The mixing conditions can be adjusted upstream of applying the MFC dispersion liquid layer to a support such as inside the MFC supply unit.

[0078] The mixing conditions can be adjusted in a device for applying the MFC dispersion liquid layer to a support.

[0079] The provided MFC dispersion liquid can have a dry solid content of about 2.5 to 25% by weight, preferably about 2.5 to 15% by weight, about 2.5 to 10% by weight, or about 2.5 to 8% by weight.

[0080] Regardless of the dry solid content, the viscosity of the MFC dispersion liquid can exceed about 4 Pa·s at a shear rate of 20 s -1 −1.

[0081] The viscosity can be measured for the dispersion liquid at a temperature of about 20 to 80 °C, preferably about 20 to 60 °C. A preferred method for measuring the viscosity is to use a rheometer with a bob-cup shape, for example, an Anton Paar MCR 302 dynamic rotational rheometer.

[0082] The average film thickness of the dry MFC film can be about 5 to 60 μm, preferably 10 to 50 μm, 15 to 45 μm, or 20 to 40 μm.

[0083] The film basis weight of the dry MFC film is about 4 to 80 g / m 2 , preferably 8 to 67 g / m 2 , 12 to 60 g / m 2 , 16 to 53 g / m 2 or 20 to 45 g / m 2 and may be.

[0084] The content of the dispersion medium in the dry MFC film (F’) can be about 0.1 to 20% by weight, preferably 1 to 15% by weight, or 2 to 14% by weight.

[0085] The film-forming component content of the dry MFC film (F’) may be at least 80 to 99.9% by weight, preferably 85 to 99% by weight, or 86 to 98% by weight.

[0086] The film-forming component can contain at least 60% by weight of MFC, at least 70% by weight of MFC, or at least 80% by weight of MFC.

[0087] The film width of the dry MFC film (F’) may be about 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m.

[0088] This method may further include measuring the concentration of at least one component in the wet MFC film and / or the dry MFC film at at least two data points spaced apart from each other in the thickness direction of the MFC film.

[0089] Measurement data indicating the component content such as additives and impurities at various points separated in the thickness direction can be saved and used to track the quality of the MFC film and / or for grading the MFC film obtained as a result.

[0090] The component may be at least one unintended substance in the wet MFC film or the dry MFC film.

[0091] Therefore, this measurement can be used to detect contamination of the MFC film. Furthermore, for example, since it is also possible to detect the type of contamination such as grease and oil, it becomes easier to identify the source of contamination.

[0092] According to a second aspect, a device for manufacturing a microfibrillated cellulose (MFC) film from a microfibrillated cellulose (MFC) dispersion is provided. The device includes a support guide device configured to guide a continuous support, a casting device configured to apply the MFC dispersion as a wet MFC film onto the support, a drying device configured to remove a dispersion medium from the wet MFC film to form a dry MFC film, at least one measuring device configured to provide data indicative of the concentration of at least one component in the wet MFC film and / or the dry MFC film at at least two data points spaced laterally across the width of the MFC film and / or longitudinally along the length of the MFC film, and a controller configured to receive the data and perform at least one of the tasks of: i) controlling at least one manufacturing parameter that affects the concentration of the at least one component in the MFC film, and ii) recording the data as a chemical map of the dry MFC film, wherein a plurality of data points are each associated with a respective position on the dry MFC film. The device may be configured to perform the method disclosed above.

[0093] The support guide may be configured to guide a support having a width of at least about 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m.

[0094] The support may be a continuous non-porous support such as a non-porous support, particularly a metal belt, particularly a steel belt, a polymer belt, or a polymer-coated belt. The metal belt may be coated, for example, with a ceramic material.

[0095]

[0096] ​The device may further include a dehydration device upstream of the drying device, and the measuring device is arranged downstream of at least a part of the dehydration device.

[0097] Therefore, the measurement can be carried out downstream of one or more dehydration steps, for example, downstream of the entire dehydration step but before the drying step, or between sub-steps of the dehydration process.

[0098] It is understood that the measuring device may include a first measuring device with at least a part of the drying device arranged downstream and a second measuring device with at least a part of the dehydration device arranged downstream.

[0099] The device may further include a pre-drying device upstream of the dehydration device, and the measuring device is arranged downstream of at least a part of the pre-drying device and upstream of the dehydration device.

[0100] Therefore, an additional measuring device, or a part of the measuring device, can be arranged downstream of at least a part of the pre-drying device.

[0101] According to a third aspect, a dried MFC film having a dispersion medium content of about 0.1 to 20% by weight, preferably 1 to 15% by weight, or 2 to 14% by weight, a dry solid content of about 2.5 to 25% by weight, preferably about 2.5 to 15% by weight, about 2.5 to 10% by weight or about 2.5 to 8% by weight, and optionally a shear rate of 20 s -1 and having a viscosity exceeding about 4 Pa·s is provided for use of a device as described above for forming from an MFC dispersion.

[0102] According to a third aspect, there is provided a microfibrillated cellulose (MFC) film having a longitudinal direction parallel to the length direction of the film and a width direction perpendicular to the longitudinal direction. The MFC film has a film-forming component content of at least 80 to 99.9% by weight, preferably 85 to 99% by weight, or 86 to 98% by weight. The film-forming component contains about 50 to 100% by weight of MFC. The MFC film has a width of about 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m. The MFC film is formed from an MFC dispersion having a dry solid content of about 2.5 to 25% by weight, preferably about 2.5 to 25% by weight, and has a dispersion medium content of about 0.1 to 20% by weight, preferably 1 to 15% by weight, or 2 to 14% by weight, about 2.5 to 15% by weight, about 2.5 to 10% by weight, or about 2.5 to 8% by weight. The MFC film contains an effective amount of at least one component such as an additive or an impurity. When analyzing the component content every 1 cm of the width of the MFC film along the width direction of the MFC film and / or along the length direction of the MFC film, the standard deviation is less than 1% by weight.

[0103] In the MFC film, the film-forming component can contain at least 60% by weight of MFC, at least 70% by weight of MFC, or at least 80% by weight of MFC.

[0104] The average film thickness may be about 5 to 60 μm, preferably about 10 to 50 μm, about 15 to 45 μm, or about 20 to 40 μm.

[0105] The basis weight of the film is about 4 to 80 g / m 2 , preferably about 8 to 67 g / m 2 , about 12 to 60 g / m 2 , about 16 to 53 g / m 2 or about 20 to 45 g / m 2 and may be.

[0106] According to a fourth aspect, a method for producing an MFC film from a microfibrillated cellulose (MFC) dispersion is provided. The method includes providing an MFC dispersion, applying a layer of the MFC dispersion to a support to form a wet MFC film, subjecting the wet MFC film on the support to at least one drying step to form a dried MFC film, using a spectroscopic measurement device to provide data indicative of the material composition of the wet MFC film and / or the dried MFC film at at least two data points spaced laterally across the width of the MFC film and / or longitudinally along the length of the MFC film, and identifying at least one unintended contaminant based on the material composition data.

[0107] The MFC dispersion is dispersed in at least one dispersion medium and may have a dry solids content of about 2.5 to 25% by weight.

[0108] According to a fifth aspect, a device for producing a microfibrillated cellulose, MFC, film from a microfibrillated cellulose MFC dispersion is provided. The device includes a support guiding device configured to guide a continuous support, a casting device configured to apply the MFC dispersion as a wet MFC film onto the support, a drying device configured to remove the dispersion medium from the wet MFC film to form a dried MFC film, at least one spectroscopic measurement device configured to provide data indicative of the material composition of the wet MFC film and / or the dried MFC film at at least two data points spaced laterally across the width of the MFC film and / or longitudinally along the length of the MFC film, and a controller configured to receive the data and identify at least one unintended contaminant based on the material composition data indicative of the material composition.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0110] Referring to FIG. 1a, a top view of the film forming device 1 is schematically shown. FIG. 1b schematically shows a side view of the film forming device 1.

[0111] In the present disclosure, the film forming device 1 is described with reference to a film forming device 1 for forming a non - laminated film, i.e., a "self - supporting film", i.e., a film not laminated to any substrate material. Thus, as shown in FIGS. 1a - 1b, the completed film F' is peeled from the support 10 and wound onto the reel 4.

[0112] The support 10 from which the dry film F' is peeled is in a non - porous form and may preferably be provided in the form of an endless belt, such as a metal belt, such as a steel belt, or a polymer belt or a polymer - coated belt. The metal belt may be coated, for example, by a ceramic coating.

[0113] The support 10 is preferably non - porous in order to provide a smooth film surface. In particular, the support can be polished until it has a mirror finish. In the illustrated embodiment, the support 10 is an endless support that runs on a support guide in the form of a pair of pulleys 11, 12.

[0114] The MFC supply device 2 is provided to supply the MFC dispersion to the casting device 16, and the casting device 16 is configured to deposit the MFC dispersion as a thin wet film F of uniform thickness. The support 10 carrying the wet film F passes through a dryer 13 that may include one or more drying devices 131, 132. If there are a plurality of drying devices 131, 132, the drying devices may be identical to each other or may be different, for example, in terms of length. Also, the drying devices 131, 132 may be individually controlled to provide different drying parameters.

[0115] The MFC supply unit 2 may include one or more mixing devices (not shown) for mixing the MFC, the dispersion medium, and the additive (if any).

[0116] This mixing device is suitable for mixing viscous materials and, for example, means a ribbon agitator with a double helix design. In such a design, the outer helix moves the material in one direction, the inner helix moves in the opposite direction, and the entire volume is efficiently mixed. In some cases, high shear force and high shear mixers such as serrated dispersion machine blades or rotor stator type dispersion machines are required. The high shear mixer can be used alone or in combination with other mixers. In addition to or instead of the mixing device, there may be a pipeline equipped with a pump that moves the material from the lower part to the upper part of the MFC supply unit, thereby improving the distribution of the additive in the vertical direction. The non-uniform distribution of the additive in the wet film F or the dry film F' may be related to insufficient mixing in the MFC supply 2, but this can be improved by increasing the mixing speed and the shear rate.

[0117] The mixing configuration can be controlled from the viewpoints of the operating speed, temperature, and / or duty cycle. The control of the mixing device may be provided by a separate controller or by the controller 3 that also controls other parts of the film forming device 1.

[0118] The MFC supply unit 2 can also include a controllable configuration for selectively supplying one or more additives to the MFC dispersion.

[0119] In the MFC supply unit 2, it may be possible to control the temperature of the whole or a part of the MFC supply unit.

[0120] The MFC supply unit 2 can also include a controllable heating / cooling device capable of controlling the temperature of the MFC dispersion. In some cases, increasing the temperature reduces the viscosity of the MFC dispersion, making mixing more efficient and thus improving the distribution of the additives. On the other hand, if the temperature is too high, certain additives may thermally degrade, and unwanted substances may contaminate the film. The temperature can be controlled, for example, by a heat exchanger, a heating / cooling jacket around the chest, and / or direct or indirect steam.

[0121] Furthermore, the MFC supply unit 2 can include a pH and / or conductivity adjustment device. For example, this configuration can consist of the possibility of adding an acid and / or a base to the MFC dispersion and measuring the pH in the MFC dispersion. In another example, this arrangement consists of the possibility of adding a salt solution to the MFC dispersion and measuring the conductivity of the MFC suspension. The pH and / or conductivity of the dispersion can potentially affect the surface charge of all or some of the components, and as a result, affect the ease of mixing between the components. In some cases, a chemical reaction between the components occurs due to a change in pH, and it may appear in the chemical composition measured from the wet film or the dry film.

[0122] The casting device 16 can include one or more mixing devices (not shown) for mixing the MFC, the dispersion medium, and the additives if present. The mixing device can be controllable from the perspective of the operating speed and / or the duty cycle.

[0123] The casting device 16 can also include a controllable configuration for selectively supplying one or more additives to the MFC dispersion. Also, in the casting device, it is possible to control the temperature of part or all of the casting device 16.

[0124] Optionally, a dehydration device 133 such as a press can be provided upstream of the drying devices 131, 132. Such a dehydration device 133 is known per se.

[0125] For example, dehydration may be performed by applying a press fabric that directly contacts the wet MFC film and passing the wet MFC film disposed between the press fabric and the support through a pressing device. Alternatively, dehydration can be performed by applying a porous wire or membrane that directly contacts the wet MFC film and passing the wet MFC film disposed between the porous wire or membrane and the support through a vacuum dehydrating device, wherein the porous wire or membrane covers one or more vacuum cavities that remove the dispersion medium from the wet MFC film.

[0126] Furthermore, optionally, a preliminary drying device 134 can be provided upstream of the dehydration device 133.

[0127] In other embodiments, the drying devices 131, 132, and the preliminary drying device 134 if present can use the same or different drying techniques, for example, each can be selected according to the non-limiting options described herein.

[0128] One or more measuring devices 14a, 14b, 14c, 14d, 14e are provided either inside or outside the dryer 13 for measuring at least one parameter indicating the concentration of at least one component such as an additive or chemical composition in the wet MFC film F and / or the dry MFC film F'. For example, the measuring device 14a may be provided between a pair of drying devices 131, 132 inside the dryer 13. As another example, the measuring device 14b may be provided downstream of the drying devices 131, 132 inside the dryer 13. As yet another example, the measuring device 14c may be provided downstream and outside the dryer 13. For example, a cooling device (not shown) can also be provided between the dryer 13 and the measuring device 14c.

[0129] It is understood that it is also possible to provide one, two, three, four, or all of the measuring devices 14a, 14b, 14c, 14d, 14e shown above.

[0130] When a dehydration device 133 is provided upstream of the drying devices 131 and 132, a measuring device 14d can be provided downstream of the dehydration device 133 and upstream of the drying devices 131 and 132. In some embodiments, the measuring device or a sub - part thereof can also be provided downstream of a part of the dehydration device 133, for example, between sub - steps of the dehydration device 133, or between dehydration devices when a plurality of dehydration devices are provided.

[0131] It is also possible to provide a measuring device 14e upstream of the dehydration device 133.

[0132] A controller 3 can be provided for controlling at least the dryer 13 and the measuring devices 14a, 14b, 14c, 14d, 14e. Optionally, the controller can also control further functions or all functions of the film forming device 1. The controller 3 can also control the dehydration device 133 if present, and the pre - drying device 134 if present.

[0133] The controller 3 can also control the operation of the MFC supply unit 2 and / or the casting device 16. In particular, the control of the mixing device, the device for supplying one or more additives, temperature, pH and / or conductivity can be provided by a separate controller or by the controller 3 that also controls other parts of the film forming device 1.

[0134] FIG. 2 is a schematic cross - sectional view taken along line A - A of FIG. 1a, showing a first embodiment of a drying device that can be arranged within the dryer 13.

[0135] Drying and pre - drying can be carried out by evaporation, impingement drying with hot gas / air, infrared (IR) drying, microwave, near - infrared (NIR) drying, UV drying, radiation drying, thermal heating, heating of the support by steam or electricity, or other methods or combinations of methods well known in the art.

[0136] It is understood that any of the drying techniques described herein can be controlled along the entire width and / or length of the support 10. For example, the technique of heating the support 10 from below can also be easily divided into zones as needed.

[0137] The drying apparatus shown in FIG. 2 is a controllable convective drying apparatus that selectively supplies dried, preferably warm or hot gas, such as air, towards the wet film F.

[0138] In the drying apparatus shown in FIG. 2, three individually controllable convective zones 1311a, 1311b, 1311c are provided. It is understood that the number of convective zones 1311a, 1311b, 1311c can be selected according to the width of the film and the support, and the required resolution.

[0139] For each of the convective zones 1311a, 1311b, 1311c, the gas flow rate and / or gas flow direction and / or gas temperature and / or gas composition (e.g., moisture content) can be individually controlled by the controller 3 by controlling the respective blowers, the respective nozzles, the respective heaters, and / or the respective gas mixers. Alternatively, or in addition, the supply of gas to each of the convective zones 1311a, 1311b, 1311c can be controlled by a valve (not shown).

[0140] Therefore, during operation, the drying effect of each zone 1311a, 1311b, 1311c is individually controlled by the controller 3. For example, by providing a lower gas flow rate and / or a lower temperature and / or a higher moisture content to the zones 1311a, 1311c near the side edges of the film F, the drying effect at the side edge portions of the film F can be reduced.

[0141] In the embodiment of FIG. 2, the collision width of the drying gas can be made narrower than the collision width of the MFC films F, F'. For example, the collision width can be 30 - 70 mm, preferably 40 - 60 mm or about 50 mm, which is narrower than the width of the films F, F'.

[0142] Figure 3a is a schematic cross-sectional view taken along line A-A of Figure 1a, showing a first version of a second embodiment of a drying device that can be arranged within the dryer 13.

[0143] The drying device shown in Figure 3a has a single convection zone 1311, which can be operated in the same way as one of the convection zones described with reference to Figure 2, and the gas flow rate and / or the gas flow direction and / or the gas temperature and / or the gas composition (such as the moisture content) can be controlled by the controller 3.

[0144] Figure 3a is provided with at least one discharge port 1312a, 1312b, which can move in the horizontal and / or vertical directions, can optionally be controlled by the controller 3, and can be arranged in a desired horizontal direction with respect to the film F. The discharge ports 1312a, 1312b are connected to an extraction device such as a fan that can be controlled by the controller 3, and the extraction speed can be controllably adjusted by the controller 3.

[0145] Figure 3b schematically shows a second version of the second embodiment of the drying device, where the inlets to the exhaust ports 1312a, 1312b are arranged horizontally inside the ends of the MFC films F, F', preventing the drying gas from reaching the ends of the MFC films.

[0146] Figure 3c schematically shows a third version of the second embodiment of the drying device, where the convection zone 1311 is configured to provide a larger drying gas flow in its central horizontal part, for example, by reducing the gas flow resistance in the central part of the convection zone 1311 compared to the edge part of the convection zone 1311. This embodiment can be combined with the embodiments of Figure 3a and / or Figure 3b.

[0147] Therefore, during operation, the drying air and / or hot air is extracted from the region of the side edge part, preventing interaction with the wet film F, thereby reducing the drying effect at the side edge part of the film F.

[0148] Figure 4 is a schematic cross-sectional view taken along line A-A of FIG. 1a, and shows a third embodiment of a drying device that can be disposed within dryer 13.

[0149] The drying device shown in FIG. 4 has a single convection zone 1311, which can be operated in the same manner as the convection zone described with reference to FIGS. 3a-3c.

[0150] FIG. 4 is provided with at least one shield 1313a, 1313b, which are movable in the lateral direction and can be arbitrarily controlled by controller 3, whereby the shields 1313a, 1313b can be disposed at a desired lateral position with respect to film F.

[0151] Therefore, during operation, the incoming high temperature and / or drying gas is diverted from the side edge portions, so there is a possibility that the drying effect at the side edge portions of film F is reduced.

[0152] Figure 5 is a schematic cross-sectional view taken along line A-A of FIG. 1a, and shows a fourth embodiment of a drying device that can be disposed within dryer 13.

[0153] The drying device shown in FIG. 5 has a single convection zone 1311, which can be operated in the same manner as the convection zone described with reference to FIGS. 3a-3c.

[0154] FIG. 5 is provided with at least one seal arrangement 1314a, 1314b, which can seal against support 10 immediately outside film F, so that the gas flow from convection zone 1311 does not impinge on support 10.

[0155] Therefore, during operation, the high temperature gas is prevented from reaching support 10, which is a metal support and has a higher thermal coefficient than film F, and the heating of the support outside the lateral direction of film F is reduced, and thus the drying effect at the side edge portions of film F is also reduced.

[0156] FIG. 6 is a schematic cross-sectional view taken along line A-A of FIG. 1a and shows a fifth embodiment of a drying device that can be arranged within dryer 13.

[0157] The drying device shown in FIG. 6 is a controllable radiant drying device for selectively irradiating a wet film F with radiation such as infrared (IR) radiation.

[0158] In the drying device shown in FIG. 6, three individually controllable radiation zones 1315a, 1315b, 1315c are provided. It is understood that the number of irradiation zones 1315a, 1315b, 1315c can be selected according to the width of film F and support 10 and the required resolution.

[0159] For each radiation zone 1315a, 1315b, 1315c, the radiation intensity and / or radiation duty cycle can be individually controlled by controller 3, for example, by controlling each respective radiation source and / or by controlling a radiation filter or valve.

[0160] Thus, during operation, the drying effect in each radiation zone 1315a, 1315b, 1315c is individually controlled by controller 3. For example, in order to reduce the drying effect at the side edge portions of film F, it is also possible to irradiate the irradiation zones 1315a, 1315c near the side edge portions of the film.

[0161] FIG. 7 is a schematic cross-sectional view taken along line A-A of FIG. 1a and shows a sixth embodiment of a drying device that can be arranged within dryer 13.

[0162] The drying device shown in FIG. 7 has a single radiation zone 1315, which can be operated in the same manner as one of the radiation zones described with reference to FIG. 6.

[0163] FIG. 7 shows at least one shield 1316a, 1316b which is laterally movable and optionally controllable by the controller 3, and the shields 1316a, 1316b can be arranged in a desired lateral direction with respect to the film F. The shield may be completely opaque to radiation. Alternatively, the shield may be variable, for example controllable by the controller 3, transparent to radiation, or partially transparent to radiation, etc.

[0164] The shields 1316a, 1316b can be operated to mask only the support 10 to reduce heating of the support 10, or to mask both the support 10 and the side edge portions of the film F.

[0165] Thus, during operation, the incident radiation is shielded from the support 10 and also, if necessary, from the side edge portions, so that the drying effect at the side edge portions of the film F is reduced, and there is a possibility that the drying effect at the side edge portions of the film is reduced.

[0166] FIG. 8 is a schematic cross-sectional view taken along line A-A of FIG. 1a and shows a seventh embodiment of a drying device that can be arranged within the dryer 13.

[0167] The drying device shown in FIG. 8 has a single radiation zone 1315 which can be operated in the same way as one of the radiation zones described with reference to FIG. 6.

[0168] FIG. 8 shows at least one injector 1317a, 1317b for a dispersion medium and / or a coolant. The injectors 1317a, 1317b are controllable by the controller 3 and can selectively apply a dispersion medium and / or a coolant to the film F and / or the support 10 immediately outside the film to increase the moisture level in the film and / or cool the film F and / or the support 10.

[0169] Thus, during operation, as the moisture level of the film F is selectively increased and / or as the support 10 and, optionally, the side edge portions are also cooled, the drying effect at the side edges of the film F is reduced, and there is a possibility that the drying effect at the side edge portions of the film F is reduced.

[0170] Thus, by adjusting the drying effect and, if present, the dehydration effect, the movement of the additives can also be adjusted.

[0171] FIG. 9 is a schematic cross-sectional view taken along line B-B of FIG. 1a and shows a first embodiment of a measuring device that can be arranged inside or outside the dryer 13.

[0172] In the measuring device 14a shown in FIG. 9, the measuring sensor is connected to the controller 3 and is formed as a 1D sensor (line sensor) having a plurality of sensor zones 141a, 141b, 141c, 141d, and each sensor zone can generate sensor data for a laterally limited portion of the film F and optionally the support 10. The number of sensor zones 141a, 141b, 141c, 141d can be arbitrarily selected according to the required resolution.

[0173] Various sensing techniques can be utilized.

[0174] For example, the sensor can use infrared (IR) spectroscopy, near-infrared (NIR) spectroscopy, or Raman spectroscopy to provide data corresponding to the composition of the film F, and thereby derive the composition of the material based on the resulting spectral data.

[0175] Using spectroscopy such as near-infrared spectroscopy (NIR) and Raman spectroscopy, it is possible not only to measure the dry solid content and / or chemical composition at points on the surface of a wet or dry MFC film, but also to measure the dry solid content and / or chemical composition at various points along the thickness direction of the wet MFC film or the dry MFC films F, F'.

[0176] Thus, in effect, a 2D map or a 3D map of the additive content of the wet MFC film or the dry MFC film F, F' can be created.

[0177] The sensor can operate continuously or at regular intervals to derive the composition profile of the film F, and this profile can be used as an input to the controller 3 for determining the operating method of the drying device, the casting device 16, and / or the MFC supply unit 2.

[0178] FIG. 10 is a schematic cross-sectional view taken along the line B-B of FIG. 1a, showing a second embodiment of a measuring device that can be arranged inside or outside the dryer 13.

[0179] In the measurement arrangement shown in FIG. 10, the measurement sensor 1422 is connected to the controller 3 and may be formed as a point sensor that can scan across the films F, F' and optionally also across the support 10. The scan can be achieved by moving the measurement sensor along the guide 1421 and / or by using a beam guide.

[0180] The sensor can use any of the sensing techniques described with reference to FIG. 9.

[0181] Similar to the arrangement described with reference to FIG. 9, the sensor 1422 can operate continuously or at regular intervals to derive the temperature or composition profile of the films F, F', and this profile can be used as an input to the controller 3 for determining how to operate the drying device 13, the casting device 16, and / or the MFC supply unit 2.

[0182] FIG. 11 is a schematic cross-sectional view taken along the line B-B of FIG. 1a, showing a third embodiment of a measuring device that can be arranged inside or outside the dryer 13.

[0183] In the measurement arrangement shown in FIG. 11, a 2D sensor such as camera 1423, for example, a hyperspectral camera or an infrared (IR) camera, can be arranged so that the field of view covers the width of film F and optionally also the width of support 10.

[0184] Accordingly, camera 1423 can use any of the sensing techniques described with reference to FIG. 9.

[0185] Similar to the arrangement described with reference to FIG. 9, camera 1423 can operate continuously or at regular intervals to derive the composition profile of film F, and this profile can be used as an input to controller 3 for determining how drying device 13, casting device 16 and / or MFC supply 2 operate.

[0186] At least one measurement arrangement disclosed with respect to any one of FIGS. 9 - 11 can be applied at any position along support 10 where measurement arrangements 14a, 14b, 14c, 14d, 14e are shown.

[0187] The wet MFC film F can be formed from an MFC dispersion having a dry solids content of about 2.5 - 4 wt%, about 4 - 6 wt%, about 6 - 8 wt%, about 8 - 10 wt%, about 10 - 12 wt%, about 12 - 14 wt%, about 14 - 16 wt%, about 16 - 18 wt%, about 18 - 20 wt%, about 20 - 22 wt% or about 22 - 25 wt%, which is considered a high dry solids content MFC. Preferably, the dry solids content can be greater than 3 wt% or greater than 4 wt%.

[0188] The dry film thickness F' can be measured, as non-limiting examples, by white light interferometry, laser profilometry, or optically, by cutting the sample with a line in the machine width direction (whether cast in resin or not) and taking a microscopic image in the thickness direction of the cut cross-section (e.g., scanning electron microscopy or other applicable methods).

[0189] The thickness of the average dry film F' may be about 5 to 60 μm, 15 to 20 μm, preferably 20 to 60 μm, 10 to 50 μm, 30 to 50 μm, 15 to 45 μm, or 20 to 40 μm.

[0190] The thickness of a specific dry film F' may be 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, 25 to 30 μm, 30 to 35 μm, 35 to 40 μm, 40 to 45 μm, 45 to 50 μm, 50 to 55 μm or 55 to 60 μm.

[0191] The basis weight of the dry film F' is about 4 to 80 g / m 2 preferably 8 to 67 g / m 2 12 to 60 g / m 2 16 to 53 g / m 2 or 20 to 45 g / m 2 and is.

[0192] The weight of a specific dry film F' is 4 to 10 g / m 2 10 to 20 g / m 2 20 to 30 g / m 2 30 to 40 g / m 2 40 to 50 g / m 2 50 to 60 g / m 2 60 to 70 g / m 2 or 70 to 80 g / m 2 and may be.

[0193] The content of the dispersion medium in the dry film F' may be about 0.1 to 20% by weight, preferably 1 to 15% by weight, or about 2 to 14% by weight.

[0194] The content of a specific dispersion medium in the dry film F' may be about 0.1 to 1% by weight, 1 to 2% by weight, 2 to 3% by weight, 3 to 4% by weight, 4 to 5% by weight, 5 to 6% by weight, 6 to 7% by weight, 7 to 8% by weight, 8 to 9% by weight, 9 to 10% by weight, 10 to 11% by weight, 11 to 12% by weight, 12 to 13% by weight, 13 to 14% by weight or 14 to 15% by weight.

[0195] The film-forming component content of the dry film F' may be 80 to 99.9% by weight, preferably 85 to 99% by weight, or 86 to 98% by weight, and the balance is a dispersion medium and / or one or more additives.

[0196] In particular, the film-forming component of the dry film F' has an MFC content of 50 to 60% by weight, 60 to 70% by weight, 70 to 80% by weight, 80 to 90% by weight, 90 to 95% by weight, or 95 to 99% by weight, and the balance is a dispersion medium and / or one or more additives.

[0197] The width of the dry film F' may be about 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m.

[0198] The width of the specific films F, F' may be 0.3 to 0.5 m, 0.5 to 1 m, 1 to 1.5 m, 1.5 to 2 m, 2 to 2.5 m, 2.5 to 3 m, 3 to 3.5 m, or 3.5 to 4 m. The width of the corresponding support 10 is at least as wide as the film, and in some cases is about 10 to 20 cm wider than the width of the film.

[0199] By using the method of the present invention, it is possible to produce a dry MFC film F' having a uniform composition with respect to the dispersion medium and / or additives if present.

[0200] By measuring the content of the dispersion medium and / or the chemical composition of the film at a plurality of points across the width of the dry MFC film F', for example, at 1 cm intervals across the entire width of the dry MFC film F', it is possible to derive the average content of the dispersion medium and / or additives, as well as the standard deviation of said content. According to the method disclosed herein, it is possible to achieve a standard deviation of 1% by weight or less across the entire width of the MFC film F' having a width exceeding that of a laboratory-scale device.

[0201] It is also possible to affect the dry solids content and the distribution and content of additives of the films F, F' by means implemented in the casting device 16.

[0202] For example, the nozzle of the casting device 16 can be adjusted to vary the thickness of the wet MFC dispersion applied to the support 10. For example, the thickness of the portions where the MFC films F, F' dry faster can be increased.

[0203] Also, it is possible to vary the temperature of the nozzle, and as a result, the temperature of the wet MFC films F, F' applied to the support 10 varies across the width of the support 10.

[0204] It is also possible to locally cool or heat the support 10 at the casting device 16 or immediately downstream thereof.

[0205] Also, it is possible to detect, for example, the presence on the support 10 of a collection of impurities or components adhering to the support 10, which indicates that the non-porous support needs to be cleaned. The collection of impurities or components present on the support 10 may mean that impurities are added to the film or that the components / additives are unevenly distributed.

[0206] Also, it is possible to detect partial clogging or impurities in the nozzle that cause non-uniformity in the film thickness or distribution of additives within the film.

[0207] FIG. 12 schematically shows a method according to the present disclosure.

[0208] Step 1001 represents a mixing operation of mixing the MFC with a dispersion medium and, optionally, additives to form an MFC dispersion.

[0209] Step 1002 represents an application operation of applying the MFC dispersion to the support 10.

[0210] Step 1003 is optional and represents a pre-drying step that can be carried out according to any of the drying methods disclosed above.

[0211] Step 1004 is optional and represents a first measurement step that can be executed according to any of the measurement methods disclosed above.

[0212] Step 1005 is optional and discloses a dehydration step that can be executed according to any of the dehydration methods disclosed above.

[0213] Step 1006 represents a second measurement step that can be executed according to any of the measurement methods disclosed above. The second measurement step is used only when the dehydration step 1005 precedes.

[0214] Step 1007 represents a main drying step, which can be executed according to any of the drying methods disclosed above.

[0215] Step 1008 represents a third measurement step that can be executed according to any of the measurement methods disclosed above.

[0216] Step 1009 represents a peeling step, where the dried MFC film F’ is removed from the support 10, for example, by a doctor blade.

[0217] Step 1010 represents a packing step, where the dried MFC film F’ is packed for shipment, for example, by being wound onto a reel.

[0218] Step 1020 represents a measurement data receiving step, where measurement data or signals from the measurement steps 1004, 1006, 1008 are received, for example, by the controller 3.

[0219] Step 1021 represents a processing step where the measurement data or signals are processed to derive information regarding the composition of the MFC films F, F’ at respective measurement points.

[0220] Step 1022 represents a control step, and control data or a control signal is transmitted as an input for controlling one or more of the mixing step 1001, the application step 1002, the pre-drying step 1003, the dehydration step 1005, and the drying step 1007 according to the content disclosed above.

[0221] Step 1023 represents a mapping step, and a 2D or 3D composition map representing the composition of the dried MFC film is created. The mapping step 1023 may be performed based on data received in one or more of the measurement steps 1004, 1006, 1008.

Claims

1. A method for producing an MFC film from a microfibrillated cellulose (MFC) dispersion, To provide an MFC dispersion containing a dispersion medium and a film-forming component containing approximately 50 to 100% by weight of MFCs, The process involves applying a layer of MFC dispersion to a support (10) to form a wet MFC film (F), The wet MFC film (F) on the support (10) is subjected to at least one drying step to form a dried MFC film (F'), The method involves measuring at least one parameter indicating the concentration of at least one component, such as an additive or impurity, in the wet MFC film (F) and / or dry MFC film (F') at at least two data points spaced laterally across the width of the MFC film (F, F') and / or longitudinally along the length of the MFC film (F, F'), i) The task of adjusting at least one manufacturing parameter that affects the concentration of at least one component in the MFC film (F, F') according to the at least one parameter, and ii) A task of recording the at least one parameter for each of the data points and providing a chemical map of the dry MFC film (F') including a plurality of data points each associated with each position on the dry MFC film (F'). Perform at least one of the following: A method that includes this.

2. The method according to claim 1, wherein the measuring step is performed after at least a portion of the at least one drying step.

3. The method according to claim 1, further comprising at least one dehydration step prior to the at least one drying step, wherein the measuring step is performed after at least a portion of the at least one dehydration step and before the at least one drying step.

4. The method according to claim 1, wherein adjusting the at least one manufacturing parameter includes changing the drying conditions and / or changing the dehydration conditions.

5. The method according to claim 4, wherein changing the drying conditions includes reducing the drying effect at at least one side edge portion of the wet MFC film (F).

6. The method according to claim 4, wherein changing the drying conditions includes guiding the drying gas away from at least one side edge portion of the MFC film (F, F').

7. The method according to claim 4, wherein changing the drying conditions includes extracting a drying gas from at least one side edge portion of the MFC film (F, F').

8. The method according to claim 4, wherein changing the drying conditions includes, for example, masking the side edges of the MFC film (F, F') from drying gas and / or radiation.

9. The method according to claim 4, wherein changing the drying conditions includes sealing the lateral support surface on the outer side edge portion of the MFC film (F, F').

10. The method according to claim 4, wherein changing the drying conditions includes selectively controlling the duty cycle, combustion gas pressure, and / or the intensity of the radiation source for providing the drying.

11. The method according to claim 4, wherein changing the drying conditions includes selectively injecting at least one of the cooling medium and the dispersion medium onto the wet MFC film (F).

12. The method according to claim 1, further comprising separating the dried MFC film (F') from the support (10) and winding the separated MFC film (F') onto a reel.

13. The method according to claim 1, wherein adjusting the at least one manufacturing parameter includes adjusting the dosage of the at least one component.

14. The method according to claim 1, wherein adjusting the at least one manufacturing parameter includes adjusting the mixing conditions of the MFC dispersion.

15. The MFC dispersion has a dry solids content of approximately 2.5 to 25% by weight, preferably approximately 2.5 to 15% by weight, approximately 2.5 to 10% by weight, or approximately 2.5 to 8% by weight, and optionally a shear rate of 20 s. －１ The method according to claim 1, wherein the viscosity is greater than approximately 4 Pa·s.

16. The method according to claim 1, wherein the average film thickness of the dried MFC film (F') is about 5 to 60 μm, preferably 10 to 50 μm, 15 to 45 μm, or 20 to 40 μm.

17. The film weight of dry MFC film (F') is approximately 4-80 g / m². ２ Preferably 8 to 67 g / m ２ , 12-60 g / m ２ 16-53 g / m ２ Or 20-45 g / m ２ The method according to claim 1.

18. The method according to claim 1, wherein the dispersion medium content of the dried MFC film (F') is about 0.1 to 20% by weight, preferably 1 to 15% by weight, or 2 to 14% by weight.

19. The method according to claim 1, wherein the film-forming component content of the dried MFC film (F') is at least 80 to 99.9% by weight.

20. The method according to claim 19, wherein the film-forming component comprises at least 60% by weight of MFC, at least 70% by weight of MFC, or at least 80% by weight of MFC.

21. The method according to claim 1, wherein the film width of the dried MFC film (F') is approximately 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m.

22. The method according to claim 1, further comprising measuring the at least one parameter indicating the concentration of at least one component in a wet MFC film and / or a dry MFC film at at least two data points spaced apart from each other in the thickness direction of the MFC film.

23. The method according to claim 1, wherein the component is at least one unintended substance in the wet MFC film or the dry MFC film.

24. A device for producing an MFC film from a microfibrillated cellulose (MFC) dispersion, Support guide devices (11, 12) configured to guide a continuous support (10), A casting device (16) configured to apply an MFC dispersion as a wet MFC film (F) onto a support (10), A drying device (13) is configured to remove a dispersion medium from a wet MFC film (F) to form a dry MFC film (F'), A measuring device (14a, 14b, 14c, 14d, 14e) is configured to provide data indicating the concentration of at least one component in a wet MFC film (F) and / or a dry MFC film (F') at at least two data points spaced laterally across the width of the MFC film (F, F') and / or longitudinally along the length of the MFC film (F, F'), A controller (3) configured to receive the aforementioned data, i) A task of controlling at least one manufacturing parameter that affects the concentration of at least one component in the MFC film (F, F'), and ii) A task of recording the data as a chemical map of a dried MFC film (F'), wherein multiple data points are each associated with their respective positions on the dried MFC film (F'). A controller (3) and configured to perform at least one of the following: A device that includes this.

25. A dry MFC film (F') having a dispersion medium content of approximately 0.1 to 20% by weight, preferably 1 to 15% by weight, or 2 to 14% by weight, is subjected to a dry solids content of approximately 2.5 to 25% by weight, preferably approximately 2.5 to 15% by weight, approximately 2.5 to 10% by weight, or approximately 2.5 to 8% by weight, and optionally at a shear rate of 20 s. －１ Use of the device according to claim 24 for forming from an MFC dispersion having a viscosity of more than approximately 4 Pa·s.

26. A microfibrillated cellulose (MFC) film having a longitudinal direction parallel to the length direction of the film and a width direction perpendicular to the longitudinal direction, The MFC film has a film-forming component content of at least 80 to 99.9% by weight. The film-forming component comprises approximately 50 to 100% by weight of MFC. The MFC film has a width of approximately 0.3 to 4 m, preferably 0.5 to 4 m, 1 to 4 m, or 2 to 4 m. The MFC film has a dispersion medium content of about 0.1 to 20% by weight, preferably 1 to 15% by weight or 2 to 14% by weight. MFC film contains at least one component such as an additive or impurity. The component content of the MFC film has a standard deviation of less than 1% by weight along the width direction and / or along the length direction of the MFC film, and the component content is analyzed every 1 cm of the width of the MFC film.

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