Method for manufacturing a molded body and molded body

Abstract

The present invention provides a method for manufacturing molded bodies that can efficiently produce pipe-shaped molded bodies. [Solution] The method for manufacturing a molded body comprises: a dispersion preparation step of preparing a dispersion by dispersing microfibrillated cellulose in water at a concentration of 0.5% by mass or more and 3% by mass or less; a sheet forming step of filtering the dispersion so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less to form a sheet-like microfibrillated cellulose-containing composition; a winding step of winding the sheet-like microfibrillated cellulose-containing composition around a rod-shaped member so that it forms multiple layers; a sealing step of sealing the microfibrillated cellulose-containing composition wound around the rod-shaped member; a vacuum drying step of vacuum drying the sealed microfibrillated cellulose-containing composition; and a molded body acquisition step of removing the rod-shaped member after vacuum drying to obtain a pipe-shaped molded body made of microfibrillated cellulose.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a molded body and a molded body.

Background Art

[0002] Techniques related to materials containing cellulose microfibrils are disclosed in Japanese Patent No. 3641690 (Patent Document 1). In addition, techniques related to a method for manufacturing a molded body of microfibrillated cellulose are disclosed in Japanese Unexamined Patent Application Publication No. 2018-100466 (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, regarding molded bodies composed of microfibrillated cellulose, pipe-shaped ones have been demanded from the viewpoint of weight reduction of products using the molded bodies and the like. It is desirable that a pipe-shaped molded body can be manufactured efficiently.

[0005] An object of the present disclosure is to provide a method for manufacturing a molded body capable of efficiently manufacturing a pipe-shaped molded body.

Means for Solving the Problems

[0006] A method for manufacturing a molded article according to this disclosure is a method for manufacturing a molded article composed of microfibrillated cellulose, comprising: a dispersion preparation step of preparing a dispersion in which microfibrillated cellulose is dispersed in water at a concentration of 0.5% by mass or more and 3% by mass or less; a sheet forming step of filtering the dispersion so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less to form a sheet-like microfibrillated cellulose-containing composition; a winding step of winding the sheet-like microfibrillated cellulose-containing composition around a rod-shaped member so that it forms multiple layers; a sealing step of sealing the microfibrillated cellulose-containing composition wound around the rod-shaped member; a vacuum drying step of vacuum drying the sealed microfibrillated cellulose-containing composition; and a molded article acquisition step of removing the rod-shaped member after vacuum drying to obtain a pipe-shaped molded article composed of microfibrillated cellulose. [Effects of the Invention]

[0007] According to this method for manufacturing molded bodies, pipe-shaped molded bodies can be manufactured efficiently. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing the appearance of a molded article according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view showing an enlarged portion of the molded body shown in Figure 1. [Figure 3] Figure 3 is a schematic perspective view showing a portion of a molded body with a folded section. [Figure 4] Figure 4 is a flowchart showing a typical manufacturing process in the manufacturing method of the molded article 11 according to one embodiment of the present disclosure shown in Figures 1 and 2. [Figure 5] Figure 5 is a schematic diagram illustrating a part of the winding process. [Figure 6] Figure 6 is a schematic diagram illustrating a part of the sealing process. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described. A method for manufacturing a molded article according to this disclosure is a method for manufacturing a molded article containing microfibrillated cellulose (hereinafter sometimes simply abbreviated as "MFC (Microfibrillated cellulose)"). The method for manufacturing a molded article comprises: a dispersion preparation step of preparing a dispersion in which microfibrillated cellulose is dispersed in water at a concentration of 0.5% by mass or more and 3% by mass or less; a sheet forming step of filtering the dispersion so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less to form a sheet-like microfibrillated cellulose-containing composition; a winding step of winding the sheet-like microfibrillated cellulose-containing composition around a rod-shaped member so that it forms multiple layers; a sealing step of sealing the microfibrillated cellulose-containing composition wound around the rod-shaped member; a vacuum drying step of vacuum drying the sealed microfibrillated cellulose-containing composition; and a molded article acquisition step of removing the rod-shaped member after vacuum drying to obtain a pipe-shaped molded article made of microfibrillated cellulose.

[0010] According to the method for manufacturing a molded article in accordance with this disclosure, the dispersion prepared in the dispersion preparation step has a concentration of microfibrillated cellulose-containing composition of 0.5% by mass or more and 3% by mass or less. With such a dispersion, since the concentration of the microfibrillated cellulose-containing composition is 0.5% by mass or more, it is easier to make the concentration uniform in the planar direction when forming a sheet-like microfibrillated cellulose-containing composition. Furthermore, since the concentration of the microfibrillated cellulose-containing composition is 3% by mass or less, the deterioration of the fluidity of the microfibrillated cellulose can be reduced, making it easier to form a suitable sheet-like microfibrillated cellulose-containing composition. The method also includes a step of filtering the dispersion so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less to form a sheet-like microfibrillated cellulose-containing composition. Therefore, when forming the sheet-like microfibrillated cellulose-containing composition, it is not necessary to prepare bags or sealing tape to create a sealed space. Furthermore, since the sheet-like microfibrillated cellulose-containing composition is formed by filtration, the risk of unevenness in the concentration of microfibrillated cellulose can be reduced. Then, a winding process is carried out on a rod-shaped member, which is selected considering factors such as the ease of removing the rod-shaped member, so that the final product becomes the desired pipe-shaped molded body. After sealing the microfibrillated cellulose-containing composition, it is dried under reduced pressure, and the rod-shaped member is removed to obtain the pipe-shaped molded body. In this case, since the pipe-shaped molded body can be obtained by removing the rod-shaped member, cutting and processing of the block-shaped molded body are unnecessary, thus reducing labor and time. Therefore, the above method for manufacturing a molded body allows for the efficient production of pipe-shaped molded bodies.

[0011] In the above method for manufacturing a molded body, the rod-shaped member may be a hollow cylindrical shape. This makes it easier to remove the rod-shaped member during the molded body acquisition process by shrinking the inner diameter side of the rod-shaped member. Therefore, the molded body acquisition process can be carried out efficiently.

[0012] In the above method for manufacturing a molded article, the rod-shaped member may be a solid cylindrical shape. By doing so, the risk of the rod-shaped member unintentionally bending during the winding process and subsequent processes can be reduced. Furthermore, deformation of the rod-shaped member can be suppressed even if the winding pressure during the winding process is high.

[0013] In the above method for manufacturing a molded body, the rod-shaped member may be flexible. This makes it easier to bend the rod-shaped member together with the molded body when obtaining a bent pipe-shaped body. Therefore, it becomes easier to obtain a pipe-shaped molded body in the shape desired by the user.

[0014] In the above-described method for manufacturing a molded body, the rod-shaped member may be made of metal. By doing so, the rigidity of the rod-shaped member can be increased, and the risk of the rod-shaped member bending unintentionally can be greatly reduced. Therefore, this method is effectively used when the user desires a straight, pipe-shaped molded body.

[0015] In the above method for manufacturing a molded article, the winding step may include a step of winding a microfibrillated cellulose-containing composition to a rod-shaped member with a thickness of 1 mm to 10 mm. By doing so, the strength of the sheet-like microfibrillated cellulose-containing composition can be easily maintained by making the thickness of the microfibrillated cellulose-containing composition in the winding step 1 mm or more. Furthermore, by making the thickness of the microfibrillated cellulose-containing composition in the winding step 10 mm or less, good flexibility can be maintained when performing the bending step, and cracking of the outer surface during bending can be easily suppressed.

[0016] In the method for manufacturing the above-mentioned molded body, the winding step may include a step of winding a single sheet-like microfibrillated cellulose-containing composition around a rod-shaped member. By doing so, it becomes easy to obtain a pipe-shaped molded body having a layer continuous in the circumferential direction. Therefore, it becomes easy to obtain a pipe-shaped molded body that is also strong in strength in the circumferential direction.

[0017] In the method for manufacturing the above-mentioned molded body, the winding step may include a step of spirally winding a strip-shaped microfibrillated cellulose-containing composition around a rod-shaped member. By doing so, it becomes easy to adjust the thickness and length of the microfibrillated cellulose-containing composition while spirally winding it by using the strip-shaped microfibrillated cellulose-containing composition in the longitudinal direction of the rod-shaped member. Therefore, it becomes easy to obtain a pipe-shaped molded body having the thickness and length desired by the user.

[0018] In the method for manufacturing the above-mentioned molded body, the sealing step may include a step of covering the microfibrillated cellulose-containing composition wound around the rod-shaped member with a breathable cloth substrate and then sealing it together with the cloth substrate. By doing so, it becomes easy to smoothly perform the subsequent vacuum drying step while suppressing the occurrence of deformation and deviation of the microfibrillated cellulose-containing composition wound around the rod-shaped member. Therefore, a pipe-shaped molded body can be obtained more efficiently.

[0019] In the method for manufacturing the above-mentioned molded body, the sealing step may include a step of sealing the microfibrillated cellulose-containing composition wound around the rod-shaped member with at least any one of film-like polyethylene, film-like vinyl chloride, film-like PA6 (6 nylon) and film-like PA66 (66 nylon). Such film-like members are relatively inexpensive and difficult to break, so they are preferably used in the sealing step.

[0020] In the method for manufacturing the above-described molded body, the reduced-pressure drying step may include a step of drying the microfibrillated cellulose-containing composition under reduced pressure while maintaining the temperature and pressure below the vapor pressure of water so that the water does not freeze and does not boil. By doing so, the reduced-pressure drying of the microfibrillated cellulose-containing composition can be carried out more appropriately. Therefore, a pipe-shaped molded body can be obtained more efficiently.

[0021] In the method for manufacturing the above-described molded body, after the winding step, it may include a bending step of bending the microfibrillated cellulose-containing composition wound around the rod-shaped member together with the rod-shaped member. By doing so, when a user wants to obtain a bent pipe-shaped molded body, it becomes easy to carry out the bending step to cope with it. Therefore, it becomes easy to obtain a molded body desired by the user.

[0022] The molded body according to the present disclosure is a molded body composed of microfibrillated cellulose, which is pipe-shaped, and the layers of microfibrillated cellulose are laminated from the inner side to the outer side.

[0023] Such a molded body is pipe-shaped, and since the layers of microfibrillated cellulose are laminated from the inner side to the outer side, it has high rigidity and is lightweight. Therefore, it is effectively used in the applications desired by the user.

[0024] In the above-described molded body, it may be hollow cylindrical. According to such a molded body, since it is cylindrical, there are no corners on the outer surface as compared with the case of a square tube shape. Therefore, the occurrence of stress concentration and adverse effects due to corners is suppressed, and it is suitably used according to the usage form of the user.

[0025] In the above-described molded body, the ratio S1 / S2 of the bending strength S1 at a first point on the outer surface of the pipe-shaped molded body to the bending strength S2 at a second point on the outer surface rotated 90 degrees from the first point may be 0.9 or more and 1.1 or less. With such a molded body, when assembling or manufacturing a product using the pipe-shaped molded body, the difference between the bending strength at the first point and the bending strength at the second point rotated 90 degrees is relatively small, so when considering the strength of the assembled product, there is no need to be too concerned about the orientation during assembly. Therefore, the convenience of using pipe-shaped molded bodies can be improved.

[0026] The above-described molded body may have a folded portion. Such a molded body makes it easier to effectively utilize the folded portion to meet user needs. Therefore, convenience can be improved.

[0027] [Details of the embodiments of this disclosure] Embodiments of the present disclosure will be described below. In the following drawings, identical or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0028] Figure 1 is a schematic perspective view showing the appearance of a molded article according to one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view showing an enlarged portion of the molded article shown in Figure 1. Figure 2 is a cross-sectional view taken along the II-II section shown in Figure 1.

[0029] Referring to Figures 1 and 2, the molded body 11 according to one embodiment of the present invention is pipe-shaped. Specifically, the molded body 11 is hollow cylindrical. In this embodiment, the molded body 11 is a circular tube. The thickness of the molded body 11, that is, the distance from the outer surface 13 to the inner surface 14, is indicated by the arrow T in Figure 2. The thickness of the molded body 11, the outer diameter of the molded body 11, the inner diameter of the molded body 11, and the length of the molded body 11 in the longitudinal direction are arbitrarily determined depending on the application and intended use. For example, an inner diameter of 5 mm or more and 80 mm or less, and a thickness of 1 mm or more and 5 mm or less are preferred from the viewpoint of weight and rigidity.

[0030] The molded body 11 is composed solely of microfibrillated cellulose 12. Specifically, the molded body 11 is a hollow cylindrical shape formed by the aggregation of microfibrillated cellulose 12.

[0031] Microfibrillated cellulose 12, also known as cellulose nanofiber, is a cellulose fiber in the form of microfibrils. For example, the raw materials for microfibrillated cellulose 12 can be derived from plants, animals, or microorganisms. Furthermore, materials derived from chitin or chitosan may also be used.

[0032] The fiber diameter of the microfibrillated cellulose 12 may be between 10 nm and 50 nm. This allows the microfibrillated cellulose 12 within the molded body 11 to be more densely intertwined, thereby increasing rigidity.

[0033] In this embodiment, layers 15 of microfibrillated cellulose 12 are formed in the molded body 11 by laminating them from the inside outwards.

[0034] Furthermore, in this embodiment, the ratio S1 / S2 of the bending strength S1 at a first point 16 on the outer surface 13 of the pipe-shaped molded body 11 to the bending strength S2 at a second point 17 on the outer surface 13 rotated 90 degrees from the first point 16 is 0.9 or more and 1.1 or less. In this embodiment, this is the bending strength when a load is applied in the direction indicated by arrow F at the first point 16 and the second point 17 located on the same cross-section perpendicular to the longitudinal direction of the pipe-shaped molded body 11. Specifically, for example, the above ratio at the first point 16 and the second point 17 is preferably 0.95 or more and 1.05 or less, and more preferably 0.98 or more and 1.02 or less. The molded body 11 in this embodiment is isotropic. Such a molded body 11 can be obtained, for example, by the manufacturing method shown below. For example, if a composition containing microfibrillated cellulose is made into a sheet, multiple sheets are stacked to form a block, and this block is then machined into a pipe shape, the above ratio will be less than 1 / 20 or greater than 20, more specifically, less than 1 / 80 or greater than 80. Since a molded body formed by machining such a block of stacked material into a pipe shape is anisotropic, the above ratio values ​​will be obtained. Furthermore, the machining process itself requires a long time and considerable effort to produce a pipe-shaped molded body. Moreover, when assembling or manufacturing products using such molded bodies, the difference between the bending strength at the first point and the bending strength at the second point rotated 90 degrees becomes large, so when considering the strength of the assembled product, the orientation during assembly must be taken into consideration. Consequently, the convenience of using pipe-shaped molded bodies is reduced.

[0035] Such a molded body 11 is pipe-shaped, and since layers 15 of microfibrillated cellulose 12 are laminated from the inside out, it is highly rigid and lightweight. Therefore, it can be effectively used in applications desired by the user.

[0036] In this embodiment, the molded body 11 is hollow and cylindrical. Because the molded body 11 is cylindrical, there are no corners on the outer surface 13 compared to the case of a rectangular tube. Therefore, stress concentration and problems caused by corners are suppressed, and it can be used suitably according to the user's usage.

[0037] In this embodiment, the ratio S1 / S2 of the bending strength S1 at a first point 16 on the outer surface 13 of the pipe-shaped molded body 11 to the bending strength S2 at a second point 17 on the outer surface 13 rotated 90 degrees from the first point 16 is 0.9 or more and 1.1 or less. With such a molded body 11, when assembling or manufacturing a product using the pipe-shaped molded body 11, the difference between the bending strength at the first point 16 and the bending strength at the second point 17 rotated 90 degrees is relatively small, so when considering the strength of the assembled product, there is no need to be too concerned about the orientation during assembly. Therefore, the convenience of using the pipe-shaped molded body 11 can be improved.

[0038] The molded body may also have a folded portion. Figure 3 is a schematic perspective view showing a part of a molded body having a folded portion. Referring to Figure 3, the molded body 18 is pipe-shaped and is formed by laminating layers 15 of microfibrillated cellulose 12 from the inside to the outside, as shown in Figure 2. The molded body 18 has a folded portion 19, which is a folded part. The folded portion 19 has a gently curved shape. Such a molded body 18 can be efficiently manufactured by using a hollow cylindrical and flexible rod-shaped member 21. An example of a method for manufacturing such a molded body 18 will be described in detail later.

[0039] Next, an outline of the manufacturing method for the molded article 11 according to one embodiment of this disclosure will be described. Figure 4 is a flowchart showing a typical manufacturing process in the manufacturing method for the molded article 11 according to one embodiment of this disclosure shown in Figures 1 and 2.

[0040] Referring to Figure 4, first, in the dispersion preparation step, a dispersion is prepared by dispersing microfibrillated cellulose in water at a concentration of 0.5% by mass or less (in Figure 4, step S11; hereafter, "step" will be omitted). In this case, the desired concentration within the above range, for example, 1% by mass, is adjusted by dilution with water or the like.

[0041] Next, as a sheet formation step, the dispersion is filtered to form a sheet-like microfibrillated cellulose-containing composition so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less (S12). In this case, the dispersion is filtered by suction and molded into a sheet. In this way, the dispersion is filtered by suction so that the content of microfibrillated cellulose relative to the whole is 5% by mass or more and 30% by mass or less (water content is 70% by mass or more and 95% by mass or less) to form a sheet-like microfibrillated cellulose-containing composition.

[0042] Next, in the winding step, the sheet-like microfibrillated cellulose-containing composition is wound around the rod-shaped member so that it forms multiple layers (S13). Figure 5 is a schematic diagram illustrating a part of the winding step. Referring to Figure 5, in the winding step, the rod-shaped member 21 is first prepared. In this embodiment, the rod-shaped member 21 is a solid cylinder. The rod-shaped member 21 is made of metal. The sheet-like microfibrillated cellulose-containing composition 22 is wound around this rod-shaped member 21 in the winding step. In this embodiment, one sheet-like microfibrillated cellulose-containing composition 22 is wound around the rod-shaped member 21. Specifically, the strip-shaped microfibrillated cellulose-containing composition 22 is wound in a spiral manner. In this case, it is wound so that adjacent parts overlap in some areas. When it reaches the end of the rod-shaped member 21, it is wound in the opposite direction. In this way, the microfibrillated cellulose-containing composition 22 is wound around the rod-shaped member 21 to the desired thickness.

[0043] Subsequently, as a sealing step, the microfibrillated cellulose-containing composition 22 wrapped around the rod-shaped member 21 is sealed (S14). Figure 6 is a schematic diagram illustrating a part of the sealing step. Referring to Figure 6, first, the microfibrillated cellulose-containing composition 22 wrapped around the rod-shaped member 21 is covered with a breathable fabric base material 23. In this embodiment, a nonwoven fabric is used as the breathable fabric base material 23. After covering with the fabric base material 23, the microfibrillated cellulose-containing composition 22 is sealed together with the fabric base material 23. In this case, the entire structure is covered with film-like polyethylene 24, and any open parts are sealed with sealing tape 25. A pipe 26 connected to a vacuum pump is attached to reduce the pressure inside the film-like polyethylene 24. At least one of film-like polyethylene, film-like polyvinyl chloride, film-like PA6, and film-like PA66 may be used to cover the entire structure.

[0044] Next, as a vacuum drying step, the sealed microfibrillated cellulose-containing composition 22 is vacuum-dried (S15). The microfibrillated cellulose-containing composition 22, sealed in polyethylene 24, is placed in a drying oven (not shown). Thereafter, the microfibrillated cellulose-containing composition 22 is vacuum-dried while maintaining a temperature and pressure below the vapor pressure of water so that the water does not freeze and does not boil. In this case, for example, conditions such as a temperature of 25°C and a pressure of 3.1 kPa or higher, or a temperature of 60°C and a pressure of 19.9 kPa or higher may be adopted.

[0045] Next, as a molded body acquisition step, after vacuum drying, the rod-shaped member 21 is removed to obtain a pipe-shaped molded body 11 made of microfibrillated cellulose (S16). In this case, after vacuum drying, the rod-shaped member 21 is removed from the microfibrillated cellulose-containing composition 22 by pulling it out. Regarding the removal of the rod-shaped member 21, depending on the material of the rod-shaped member 21, the rod-shaped member 21 may be dissolved using a solvent and removed. Also, if the rod-shaped member 21 is made of resin, for example, the rod-shaped member 21 may be softened and then deformed and removed.

[0046] As described above, according to the method for producing a microfibrillated cellulose-containing composition according to this disclosure, the dispersion prepared in the dispersion preparation step has a concentration of microfibrillated cellulose-containing composition of 0.5% by mass or more and 3% by mass or less. With such a dispersion, since the concentration of the microfibrillated cellulose-containing composition is 0.5% by mass or more, it is easier to make the concentration uniform in the planar direction when forming a sheet-like microfibrillated cellulose-containing composition. Furthermore, since the concentration of the microfibrillated cellulose-containing composition is 3% by mass or less, the deterioration of the fluidity of the microfibrillated cellulose can be reduced, making it easier to form a suitable sheet-like microfibrillated cellulose-containing composition. The method also includes a step of filtering the dispersion so that the content of microfibrillated cellulose is 5% by mass or more and 30% by mass or less to form a sheet-like microfibrillated cellulose-containing composition. Therefore, when forming a sheet-like microfibrillated cellulose-containing composition, it is not necessary to prepare bags or sealing tape to create a sealed space. Furthermore, since the sheet-like microfibrillated cellulose-containing composition is formed by filtration, the risk of unevenness in the concentration of microfibrillated cellulose can be reduced. Then, a winding process is carried out on a rod-shaped member, which is selected considering factors such as the ease of removing the rod-shaped member, so that the final product becomes the desired pipe-shaped molded body. After sealing the microfibrillated cellulose-containing composition, it is dried under reduced pressure, and the rod-shaped member is removed to obtain the pipe-shaped molded body. In this case, since the pipe-shaped molded body can be obtained by removing the rod-shaped member, cutting and processing of the block-shaped molded body are unnecessary, thus reducing labor and time. Therefore, the above method for manufacturing a molded body allows for the efficient production of pipe-shaped molded bodies.

[0047] In the above-described method for manufacturing a molded article, the rod-shaped member is a solid cylinder. Therefore, the risk of the rod-shaped member unintentionally bending during the winding process and subsequent processes can be reduced. Furthermore, deformation of the rod-shaped member can be suppressed even if the winding pressure during the winding process is high.

[0048] In the above-described method for manufacturing a molded body, the rod-shaped member is made of metal. Therefore, the rigidity of the rod-shaped member can be increased, significantly reducing the risk of it bending unintentionally. Consequently, this method is effectively used when the user desires a straight, pipe-shaped molded body.

[0049] In the above-described method for manufacturing a molded article, the winding step includes winding a microfibrillated cellulose-containing composition onto a rod-shaped member to a thickness of 1 mm to 10 mm. Therefore, by making the thickness of the microfibrillated cellulose-containing composition in the winding step 1 mm or more, the strength of the sheet-like microfibrillated cellulose-containing composition can be easily maintained. Furthermore, by making the thickness of the microfibrillated cellulose-containing composition in the winding step 10 mm or less, good flexibility can be maintained when performing the bending step, and cracking of the outer surface during bending can be easily suppressed.

[0050] In the above method for manufacturing a molded article, the winding step includes winding a single sheet-like microfibrillated cellulose-containing composition onto a rod-shaped member. This makes it easy to obtain a pipe-shaped molded article having layers connected in the circumferential direction. Consequently, it is easy to obtain a pipe-shaped molded article that is also strong in the circumferential direction.

[0051] In the above method for manufacturing a molded article, the winding step includes winding a strip-shaped microfibrillated cellulose-containing composition spirally around a rod-shaped member. Therefore, it becomes easy to adjust the thickness of the microfibrillated cellulose-containing composition by using the strip-shaped composition in the longitudinal direction of the rod-shaped member and winding it spirally. Consequently, it becomes easy to obtain a pipe-shaped molded article of the thickness desired by the user.

[0052] In the above method for manufacturing a molded article, the sealing step includes covering the microfibrillated cellulose-containing composition wrapped around a rod-shaped member with a breathable cloth substrate and then sealing it together with the cloth substrate. This makes it easier to carry out the subsequent vacuum drying step smoothly while suppressing deformation and unevenness of the microfibrillated cellulose-containing composition wrapped around the rod-shaped member. Therefore, a pipe-shaped molded article can be obtained more efficiently.

[0053] In the above-described method for manufacturing a molded article, the sealing step includes sealing a microfibrillated cellulose-containing composition wrapped around a rod-shaped member with at least one of film-like polyethylene, film-like polyvinyl chloride, film-like PA6, and film-like PA66. Such film-like members are relatively inexpensive and tear-resistant, and are therefore suitably used in the sealing step.

[0054] In the above method for manufacturing a molded article, the vacuum drying step includes a step of vacuum drying the microfibrillated cellulose-containing composition while maintaining it at a temperature and pressure below the vapor pressure of water so that the water does not freeze and does not boil. Therefore, vacuum drying of the microfibrillated cellulose-containing composition can be carried out more appropriately. Consequently, pipe-shaped molded articles can be obtained more efficiently.

[0055] In the above embodiment, the microfibrillated cellulose fiber diameter was set to be between 10 nm and 50 nm. However, it is not limited to this, and fiber diameters ranging from a few nanometers to several hundred or even several thousand nanometers can be used depending on the application and cost.

[0056] Next, a method for manufacturing the molded body 18 shown in Figure 3 above will be described. As a method for manufacturing the molded body 18 having a bent portion 19, for example, a bending step may be included after the winding step in which the microfibrillated cellulose-containing composition 22 wound around the rod-shaped member 21 is bent together with the rod-shaped member 21. Specifically, for example, the bending step is performed after the winding step and before the sealing step. By doing so, if a user wants to obtain a bent pipe-shaped molded body 18, it becomes easy to respond by performing the bending step. Therefore, it becomes easier to obtain a molded body that is more to the user's liking. Regarding the bending, for example, it may be bent to a near-right angle to form an L-shape, or it may be bent to form an S-shape.

[0057] Furthermore, in the above embodiment, the rod-shaped member 21 may be a hollow cylindrical shape. By doing so, when removing the rod-shaped member 21 in the molded body acquisition process, it becomes easier to remove the rod-shaped member 21 by contracting it toward the inner diameter. Therefore, the molded body acquisition process can be carried out efficiently.

[0058] In the above embodiment, the rod-shaped member 21 may be flexible. This makes it easier to bend the rod-shaped member 21 together when obtaining the bent pipe-shaped molded body 18. It also makes it easier to bend the flexible rod-shaped member 21 to a desired angle, anticipating the final shape of the molded body 18. Therefore, it becomes easier to obtain a pipe-shaped molded body 18 with the shape desired by the user.

[0059] In the above embodiment, the winding process involved winding a single sheet of MFC-containing composition onto a rod-shaped member. However, the process is not limited to this; the winding process may involve preparing multiple sheets of MFC-containing composition and winding them together so that they overlap in the radial direction. This allows for a more efficient winding process, especially when obtaining pipe-shaped molded bodies with large inner diameters.

[0060] Furthermore, in the above embodiment, a nonwoven fabric was used as the breathable fabric base material, but the fabric base material is not limited to this, and cotton fabric, synthetic fiber fabric, and glass cloth may also be used. In other words, the fabric base material may include at least one of nonwoven fabric, cotton fabric, synthetic fiber fabric, and glass cloth.

[0061] The embodiments and examples disclosed herein are illustrative in all respects and should be understood not to be restrictive in any way. The scope of the present invention is defined by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0062] 11, 18 Molded body, 12 Microfibrillated cellulose (MFC), 13 Outer surface, 14 Inner surface, 15 Layer, 16 First point, 17 Second point, 19 Bent portion, 21 Rod-shaped member, 22 Microfibrillated cellulose-containing composition, 23 Cloth base material, 24 Polyethylene, 25 Seal tape, 26 Pipe.

Claims

1. A method for producing a molded article composed of microfibrillated cellulose, A dispersion preparation step involves preparing a dispersion in which microfibrillated cellulose is dispersed in water at a concentration of 0.5% by mass or more and 3% by mass or less. A sheet forming step in which the dispersion is filtered to form a sheet-like microfibrillated cellulose-containing composition such that the content of the microfibrillated cellulose is 5% by mass or more and 30% by mass or less, A winding step in which the sheet-like microfibrillated cellulose-containing composition is wound around a rod-shaped member so as to form multiple layers, A sealing step of sealing the microfibrillated cellulose-containing composition wrapped around the rod-shaped member, A vacuum drying step in which the sealed microfibrillated cellulose-containing composition is dried under reduced pressure, A method for manufacturing a molded body, comprising: a step of obtaining a molded body by removing the rod-shaped member after vacuum drying to obtain a pipe-shaped molded body composed of the microfibrillated cellulose.

2. The method for manufacturing a molded article according to claim 1, wherein the rod-shaped member is hollow cylindrical.

3. The method for manufacturing a molded article according to claim 1, wherein the rod-shaped member is a solid cylindrical shape.

4. The rod-shaped member is flexible, as described in claim 1 or claim 2, for the method of manufacturing a molded article.

5. The method for manufacturing a molded article according to claim 1 or claim 3, wherein the rod-shaped member is made of metal.

6. The method for producing a molded article according to claim 1 or claim 2, wherein the winding step includes winding the microfibrillated cellulose-containing composition onto the rod-shaped member to a thickness of 1 mm or more and 10 mm or less.

7. The method for producing a molded article according to claim 1 or claim 2, wherein the winding step includes winding a single sheet of the microfibrillated cellulose-containing composition onto the rod-shaped member.

8. The method for producing a molded article according to claim 1 or claim 2, wherein the winding step includes winding the strip-shaped microfibrillated cellulose-containing composition spirally around the rod-shaped member.

9. The method for producing a molded article according to claim 1 or 2, wherein the sealing step includes a step of covering the microfibrillated cellulose-containing composition wrapped around the rod-shaped member with an air-permeable cloth base material and then sealing it together with the cloth base material.

10. The method for producing a molded article according to claim 1 or 2, wherein the sealing step includes sealing the microfibrillated cellulose-containing composition wrapped around the rod-shaped member with at least one of film-like polyethylene, film-like polyvinyl chloride, film-like PA6, and film-like PA66.

11. The method for producing a molded article according to claim 1 or 2, wherein the vacuum drying step includes a step of vacuum drying the microfibrillated cellulose-containing composition by maintaining it at a temperature and pressure below the vapor pressure of water so that the water does not freeze and does not boil.

12. A method for producing a molded article according to claim 1 or 2, further comprising a bending step after the winding step of bending the rod-shaped member together with the microfibrillated cellulose-containing composition that has been wound around the rod-shaped member.

13. A molded article composed of microfibrillated cellulose, It is pipe-shaped, A molded body formed by laminating the aforementioned layers of microfibrillated cellulose from the inside outwards.

14. The molded body according to claim 13, which is hollow and cylindrical.

15. The molded body according to claim 13 or claim 14, wherein the ratio S1 / S2 of the tensile strength S1 at a first point on the outer surface of the pipe-shaped molded body to the tensile strength S2 at a second point on the outer surface rotated 90 degrees from the first point is 1 / 20 or more and 20 or less.

16. A molded body according to claim 13 or claim 14, having a folded portion.

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