JP6990132B2 - Cellulose nanofiber molded body - Google Patents

Description

The present invention relates to a cellulose nanofiber molded product.

In recent years, nanotechnology has been attracting attention for the purpose of refining substances to the nanometer level and obtaining new physical properties different from the conventional properties of substances. Cellulose nanofibers (hereinafter, may be abbreviated as "CNF") produced from pulp, which is a cellulosic raw material, by chemical treatment, pulverization treatment, etc., are excellent in strength, elasticity, thermal stability, and the like. This CNF molded product is expected to be used for various purposes as a high-strength material derived from biomass.

Under these circumstances, as a composite material utilizing the strength of CNF, a fiber-reinforced composite material in which an organic polymer or the like as a matrix material is mixed with CNF has been proposed (see JP-A-2005-60680). However, such a composite material has an inconvenience such as softening in a high temperature environment because an organic polymer or the like is used for the matrix which is the main component. Therefore, in this case, sufficient strength may not be exhibited in a high temperature environment.

Japanese Unexamined Patent Publication No. 2005-60680

The present invention has been made based on the above circumstances, and an object thereof is to provide a molded product containing cellulose fiber as a main component, having excellent strength, and having low temperature dependence of the strength. That is.

The invention made to solve the above problems is mainly composed of cellulose fibers containing cellulose nanofibers, and the elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method is 3,000 MPa or more and 20,000 MPa or less. The cellulose nanofiber has a ratio (E ₉₀ / E ₂₅ ) of the elastic modulus (E ₉₀ ) at 90 ° C. calculated by the nanoindentation method to the elastic modulus (E ₂₅ ) at 25 ° C. It is a molded body.

The CNF molded body has a high elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method, and this elastic modulus (E ₂₅ ) and the elastic modulus at 90 ° C. calculated by the nanoindentation method (E 25). The ratio with E ₉₀ ) is close to 1, and it has a low temperature dependence of intensity. Therefore, the CNF molded product can exhibit high strength in a wide temperature range.

It is preferable that the cellulose fiber further contains pulp. By containing pulp together with CNF, production cost can be suppressed while maintaining sufficient strength. Further, by adding pulp, efficient dehydration becomes possible, so that productivity can be increased.

It is preferable that the pulp is beaten pulp. By using beaten pulp as the pulp, the number of hydrogen bond points between the CNF and the pulp is increased, and the strength can be relatively increased while using the pulp.

The content of pulp in the cellulose fibers is preferably 0.1% by mass or more and 70% by mass or less. By setting the pulp content in the above range, it is possible to further sufficiently suppress the production cost and further sufficiently increase the productivity while maintaining sufficient strength.

It is also preferable that the content of the cellulose nanofibers in the cellulose fibers is 50% by mass or more. Since each CNF has high strength, high elasticity, and nano size, increasing the content of such CNF increases the number of hydrogen bond points per unit volume, further increasing the strength. Can be enhanced.

The density of the CNF molded product is preferably 0.95 g / cm ³ or more and 1.5 g / cm ³ or less. With such a high density, the strength of the CNF molded product can be further increased.

Here, the "cellulose nanofiber" refers to a fine cellulose fiber obtained by defibrating a plant raw material such as pulp and having a fiber width of nano size (1 nm or more and 1000 nm or less). The "main component" means the component having the highest content on a mass basis. The elastic modulus at 25 ° C. or 90 ° C. calculated by the nanoindentation method means a value measured and calculated in accordance with ISO14577, and specifically, a value obtained by the method described in Examples. say.

According to the present invention, it is possible to provide a molded product containing cellulose fiber as a main component, having excellent strength, and having a low temperature dependence of the strength.

FIG. 1 is a flow chart showing an example method for producing the cellulose nanofiber molded product of the present invention. FIG. 2 is an explanatory diagram showing an apparatus and the like used in the preliminary dehydration step of the method of FIG. FIG. 3 is an explanatory diagram showing a pressurizing step in the method of FIG.

Hereinafter, the CNF molded product according to the embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

<CNF molded product>
The CNF molded product is a molded product containing cellulose fibers containing CNF as a main component.

(CNF)
CNF can usually be obtained by defibrating a plant raw material (fiber raw material) by a known method. The raw material of this CNF is not particularly limited as long as it is a plant raw material, but pulp is preferable.

Examples of pulp used as a raw material for CNF include broadleaf bleached kraft pulp (LKP) such as broadleaf bleached kraft pulp (LBKP) and broadleaf bleached kraft pulp (LUKP), coniferous bleached kraft pulp (NBKP), and coniferous unbleached kraft pulp (NUKP). ) And other coniferous kraft pulp (NKP) and other chemical pulp;
Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Mechanical pulp such as Chemi-Thermo Mechanical Pulp (CTMP), Bleached Thermo-Mechanical Pulp (BTMP);
Used paper pulp manufactured from used tea paper, kraft envelope used paper, magazine used paper, newspaper used paper, leaflet used paper, office used paper, cardboard used paper, upper white used paper, Kent used paper, imitation used paper, ground ticket used paper, sashimi used paper, etc.;
Examples thereof include deinked pulp (DIP) obtained by deinking used paper pulp. These may be used alone or in combination of a plurality of types as long as the effects of the present invention are not impaired.

Among these, as the pulp used as a raw material for CNF, chemical pulp is preferable, and LKP and NKP are more preferable, because a high-strength molded product can be obtained.

The method for producing CNF is not particularly limited as long as the effect of the present invention is not impaired, and a known method can be used. For example, the pulp in an aqueous dispersion state may be subjected to defibration by mechanical treatment, or may be subjected to chemical treatment such as enzyme treatment, acid treatment, TEMPO-catalyzed oxidation, and phosphoric acid esterification before defibration. ..

Examples of the defibration method by mechanical treatment include a grinder method for grinding pulp between rotating grindstones, an opposed collision method using a high-pressure homogenizer, and a pulverization method using a ball mill, a roll mill, a cutter mill, and the like.

The pulp used as a raw material for CNF may be subjected to preliminary beating before defibration. The pre-beating (mechanical pretreatment) is not particularly limited, and a known method can be used. As an example of a specific method, for example, a method using a refiner can be mentioned.

Further, the pulp which is the raw material of CNF may be chemically pretreated before defibration. Examples of this chemical pretreatment include a hydrolysis treatment using an acid such as sulfuric acid, an enzyme or the like, and an oxidation treatment using an oxidizing agent such as ozone. By performing the defibration treatment after the chemical pretreatment in this way, CNF can be efficiently obtained. Further, as a pretreatment, a treatment such as oxidation using a TEMPO catalyst or the like or phosphoric acid esterification may be performed.

The water retention level of CNF is, for example, 250% or more and 500% or less. Since dehydration is inefficient for CNF having such a high degree of water retention, there is a great advantage in using the pre-dehydration step described later, which can effectively perform dehydration. The water retention rate (%) of CNF is JAPAN TAPPI No. Measured according to 26.

The CNF preferably has a single peak in the pseudo-particle size distribution curve measured by laser diffraction in an aqueous dispersion. As described above, the CNF having one peak has been sufficiently miniaturized, can exhibit good physical properties as a CNF, and can further increase the strength of the obtained molded body. The particle size (mode) of the CNF that becomes the single peak is preferably, for example, 5 μm or more and 25 μm or less. When the CNF has the above size, various characteristics peculiar to the CNF can be exhibited better. The "pseudo particle size distribution curve" means a curve showing a volume-based particle size distribution measured using a particle size distribution measuring device (for example, a particle size distribution measuring device "LA-960S" manufactured by HORIBA, Ltd.).

The lower limit of the content of CNF in the cellulose fibers in the CNF molded product may be, for example, 30% by mass, preferably 50% by mass, 70% by mass, or 90% by mass. It may be 95% by mass or 99% by mass. By setting the content of CNF in the cellulose fiber to the above lower limit or more, the strength or the like can be increased by increasing the hydrogen bond points per unit volume or the like. On the other hand, the upper limit of the content of CNF may be 99.9% by mass, 90% by mass, 70% by mass, or 50% by mass.

(pulp)
It is preferable that the cellulose fiber in the CNF molded product further contains pulp. While pulp has a lower production cost than CNF, it does not significantly reduce its strength when used in combination with CNF. Therefore, by containing pulp together with CNF, it is possible to suppress the production cost while maintaining sufficient strength. Further, by adding pulp, efficient dehydration becomes possible, so that productivity can be increased. The fiber diameter of the pulp is usually more than 1 μm, preferably 10 μm or more.

As the pulp, LKP and NKP are preferable. It is also preferable to use pulp, which is a raw material of CNF, as the fiber. For example, using a combination of CNF and LKP made from LKP or using a combination of CNF and NKP made from NKP increases the affinity between the two by using the same starting material, and dehydration occurs. It is preferable to suppress the outflow of CNF at the time of pressurization, which leads to shortening of the total dehydration time, and to obtain a molded product having a desired shape. By using the pulp which is the raw material of CNF in this way, the affinity between CNF and pulp is further enhanced, and the outflow of CNF can be further suppressed. However, the raw material pulp of CNF and the pulp mixed with CNF may be different types.

The pulp may be beaten pulp or unbeaten pulp. By using the beaten pulp, the CNF is easily entangled, the outflow of the CNF can be further suppressed, and the strength of the molded product obtained by increasing the hydrogen bond points can be increased. On the other hand, the dehydration efficiency can be improved by using unbeaten pulp. The freeness of the beaten pulp can be, for example, 700 mL or less, 650 mL or less, 600 mL or less, or 500 mL or less. The lower limit of the freeness of the beaten pulp is not particularly limited, but may be, for example, 200 mL. On the other hand, the freeness of unbeaten pulp can be, for example, 550 mL or more, and may be 700 mL or more. The upper limit of the freeness of this unbeaten pulp is not particularly limited, but it can be, for example, 800 mL or 750 mL.

The lower limit of the pulp content in the cellulose fibers in the CNF molded product is preferably 0.1% by mass, more preferably 1% by mass, or 3% by mass or 5% by mass. It may be 10% by mass or 20% by mass. By setting the pulp content to the above lower limit or higher, the production cost can be suppressed and the productivity can be sufficiently increased. On the other hand, the upper limit of the content of this pulp is preferably 70% by mass, more preferably 50% by mass, still more preferably 30% by mass, and may be 10% by mass. By setting the pulp content to the above upper limit or less, the strength of the molded product can be further increased.

(Other ingredients, etc.)
The CNF molded product may contain cellulose fibers other than CNF and pulp, and other components other than cellulose fibers. However, the lower limit of the content of the cellulose fiber in the solid content of the CNF molded product is preferably 90% by mass, more preferably 99% by mass, still more preferably 99.9% by mass. The lower limit of the total content of CNF and pulp in the cellulose fiber is preferably 90% by mass, more preferably 99% by mass, and even more preferably 99.9% by mass. As described above, since the CNF molded product is formed substantially only of CNF or only of CNF and pulp, the strength can be further increased by strong hydrogen bonds between cellulose fibers and the like. Further, since it is formed substantially only of CNF or only of CNF and pulp, it has high thermal stability and can reduce the load on the environment.

(Physical characteristics, etc.)
The CNF molded body has an elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method of 3,000 MPa or more and 20,000 MPa or less, and is a nanoindentation method with respect to the elastic modulus (E ₂₅ ) at 25 ° C. The ratio (E ₉₀ / E ₂₅ ) of the elastic modulus (E ₉₀ ) at 90 ° C. calculated by the above method is 0.5 or more.

The lower limit of the elastic modulus (E ₂₅ ) is preferably 5,000 MPa, more preferably 7,000 MPa, and even more preferably 9,000 MPa. On the other hand, this upper limit may be 15,000 MPa or 12,000 MPa. If the elastic modulus (E ₂₅ ) is less than the lower limit, the elastic modulus may be insufficient and its use as a high-strength material may be restricted. On the other hand, there are manufacturing conditions that result in a higher density and homogeneous CNF molded product, and although there is a possibility that an elastic modulus exceeding the above upper limit can be achieved, problems such as a decrease in productivity may occur, which is preferable. do not have.

The lower limit of the above ratio (E ₉₀ / E ₂₅ ) is preferably 0.6, more preferably 0.7, and even more preferably 0.8. When the ratio (E ₉₀ / E ₂₅ ) is equal to or higher than the above lower limit, the temperature dependence of the intensity can be further reduced. On the other hand, the upper limit of this ratio (E ₉₀ / E ₂₅ ) may be, for example, 1 or 0.9.

The lower limit of the hardness of the CNF molded product is preferably 80 MPa, more preferably 100 MPa, further preferably 150 MPa, still more preferably 200 MPa, still more preferably 300 MPa, and particularly preferably 400 MPa. On the other hand, this upper limit may be 1,000 MPa or 500 MPa. The hardness refers to the nanoindentation hardness at 25 ° C. measured and calculated in accordance with ISO14577, and specifically refers to the value obtained by the method described in Examples.

The lower limit of the tensile elastic modulus (T ₂₃ ) of the CNF molded product at 23 ° C. is preferably 5,000 MPa, more preferably 7,000 MPa, further preferably 9,000 MPa, still more preferably 10,000 MPa, and 12,000 MPa. Is even more preferable, and 15,000 MPa is particularly preferable. On the other hand, this upper limit may be 20,000 MPa or 18,000 MPa. If the tensile modulus (T ₂₃ ) is less than the lower limit, the tensile modulus may be insufficient and the material may not be used as a high-strength material. On the other hand, there are manufacturing conditions that result in a higher density and homogeneous CNF molded product, and it is possible that a tensile elastic modulus exceeding the above upper limit can be achieved, but there may be problems such as a decrease in productivity. Not preferred.

The lower limit of the ratio (T ₉₀ / T ₂₃ ) of the tensile elastic modulus (T ₉₀ ) at 90 ° C. to the tensile elastic modulus (T ₂₃ ) at 23 ° C. of the CNF molded product is preferably 0.5. Is preferable, 0.65 is more preferable, and 0.7 is even more preferable. When the ratio (T ₉₀ / T ₂₃ ) is equal to or higher than the above lower limit, the temperature dependence of the intensity can be further reduced. On the other hand, the upper limit of this ratio (T ₉₀ / T ₂₃ ) may be, for example, 1, 0.9, or 0.8.

The tensile elastic modulus (T ₂₃ ) and the tensile elastic modulus (T ₉₀ ) are based on JIS K7127: 1999, respectively, and the test piece is a tensile type 2 dumbbell specified by JIS-K6251 in an environment of a temperature of 23 ° C. or 90 ° C. It is a value measured with a test speed of 10 mm / min.

The lower limit of the tensile strength of the CNF molded product is preferably 70 MPa, more preferably 100 MPa, and even more preferably 110 MPa. On the other hand, this upper limit may be 250 MPa, 220 MPa, or 200 MPa depending on the application or the like. If it is less than the above lower limit, the tensile strength is insufficient and it may not be possible to use it as a high-strength material. On the other hand, there are manufacturing conditions that result in a higher density and homogeneous CNF molded product, and although it is possible that a tensile strength exceeding the above upper limit can be achieved, problems such as a decrease in productivity may occur, which is preferable. do not have.

The upper limit of the tensile fracture strain in the CNF molded product is preferably 10%, more preferably 5%, still more preferably 4%, still more preferably 3%. On the other hand, the lower limit is preferably 0%, but may be 1%.

The above "tensile strength" and "tensile fracture strain" are based on JIS K7127: 1999, respectively, and the test piece is in the shape of a tensile No. 2 dumbbell specified by JIS-K6251 in an environment of a temperature of 23 ° C., and the test speed is 10 mm. The value measured as / minute.

As the lower limit of the density of the CNF molded product, 0.95 g / cm ³ is preferable, 1 g / cm ³ is more preferable, and 1.15 g / cm ³ is further preferable. On the other hand, the upper limit of this density is preferably 1.5 g / cm ³ , may be 1.4 g / cm ³ , or may be 1.3 g / cm ³ . If the density of the CNF molded product is less than the above lower limit, the number of hydrogen bond points may decrease and sufficient strength may not be obtained. On the other hand, when the density exceeds the above upper limit, problems such as a decrease in productivity may occur for the same reason as described above, which is not preferable.

The CNF molded body has such high strength and density and has a low temperature dependence of strength, and can be used as a material or the like as an alternative to a metal molded body, a resin molded body, wood, or the like. The shape of the CNF molded product is not particularly limited, and may be a rod shape, a plate shape, or any other shape.

<Manufacturing method of CNF molded product>
The method for producing the CNF molded product is not particularly limited, but it can be suitably produced by the following method.

An example of the method for producing the CNF molded product includes a step (pressurizing step) of pressurizing a plate-shaped body containing CNF and water in the thickness direction while heating. It is preferable that the method for producing the CNF molded product includes a pre-dewatering step for obtaining the plate-shaped body before the pressurizing step. As the pre-dewatering step, a step of dehydrating the slurry containing CNF via the mesh-like member can be adopted. That is, as shown in FIG. 1, it is preferable that the CNF slurry is made into a CNF plate-like body by a preliminary dehydration step, and this plate-like body is made into a CNF molded body by a pressure step. The manufacturing method may further include steps other than these steps. Hereinafter, the manufacturing method will be described in detail in the order of the above steps.

(Equipment, raw materials, etc. in the preliminary dehydration process)
FIG. 2 is a schematic explanatory view showing a state of an example of the preliminary dehydration step. First, the apparatus, raw materials, and the like used in the preliminary dehydration step will be described with reference to FIG.

The formwork 11 of FIG. 2 has a rectangular parallelepiped inner surface shape. Further, the formwork 11 is a frame without a bottom. The material of the formwork 11 is not particularly limited, and examples thereof include metal, resin, and wood, but metal is preferable from the viewpoint of durability against high pressure and the like.

The formwork 11 is placed, for example, on a horizontal table (not shown) having a flat upper surface. The table on which the formwork 11 is placed is not particularly limited as long as it has a strength that can withstand the pressure during the dehydration process, and a general metal, wooden, resin, or the like may be used. can. Further, at least the upper surface side of this table may be mesh-like, mesh-like, porous-like, or the like so that drainage can be efficiently performed.

Paper 13 is laid on the bottom of the formwork 11 (that is, the upper surface of the table (not shown) in the formwork 11). By laminating the paper 13 in this way, the cushioning property is enhanced, the sudden pressure change is alleviated, and the pressure can be gradually increased, so that the outflow of CNF during dehydration can be suppressed. The paper 13 is not particularly limited to Japanese paper, Western paper, paperboard, or the like, and known water-permeable paper can be used. Further, the paper 13 may be one sheet or two or more sheets may be laminated.

The lower limit of the thickness of the paper 13 is, for example, 0.05 mm, preferably 0.1 mm. By setting the thickness of the paper 13 to the above lower limit or more, more sufficient cushioning property can be ensured, and the CNF outflow suppression function by alleviating the sudden pressure increase in the preliminary dehydration step can be enhanced. On the other hand, the upper limit of this thickness is, for example, 2 mm. The thickness of the paper 13 means the thickness of the entire plurality of sheets in the laminated state when a plurality of sheets of paper are laminated and used.

Further, by laying the paper 13, the water content in the filled slurry 15 described later is transferred to the paper 13 via the mesh sheet 14, so that the dehydration efficiency can be improved. When the thickness of the paper 13 is equal to or greater than the above upper limit, the amount of water transferred to the paper 13 returns to the molded body (plate-shaped body) after the pressure is released, so that the efficiency of dehydration is lowered. .. From the viewpoint of both cushioning and dehydration, the paper 13 preferably has a low density. Further, from the viewpoint of dehydration, it is preferable that the paper 13 has a low size. From this point of view, filter paper can be preferably used as the paper 13.

A mesh-like sheet 14, which is an example of a mesh-like member, is laminated on the upper surface of the paper 13. The material of the mesh-like sheet 14 is not particularly limited, and may be metal, resin, or other fibrous material. That is, the mesh-like sheet 14 may be a wire mesh, a plastic wire, a filter cloth (woven cloth, non-woven fabric, etc.) or the like. The shape of the mesh of the mesh-like sheet 14 is not particularly limited, and may be any of plain weave, twill weave, twill weave, twill weave and the like.

As the lower limit of the number of meshes of the mesh-shaped sheet 14, 100 mesh is preferable, and 200 mesh is more preferable. By setting it to the above lower limit or more, it is possible to suppress the outflow of CNF at the time of filling before pressurization. Further, even if it is equal to or more than the above lower limit, if the number of stitches is large, the speed of pressurizing stepwise becomes slow, so that 200 mesh or more is more efficient. On the other hand, as the upper limit of the number of stitches, 500 mesh is preferable, and 400 mesh is more preferable. By setting it to the above upper limit or less, sufficient opening can be ensured and the efficiency of dehydration can be improved. However, even if it is less than the upper limit, dehydration becomes slow and it becomes difficult to perform stepwise pressurization control, so 400 mesh or less is more preferable.

The lower limit of the wire diameter of the mesh sheet 14 is preferably 25 μm, more preferably 30 μm. On the other hand, the upper limit of the wire diameter is preferably 100 μm, more preferably 50 μm. By setting the wire diameter of the mesh-shaped sheet 14 to the above lower limit or more, it is possible to secure an appropriately small opening size, and it is possible to further suppress the outflow of CNF in the preliminary dehydration step. On the other hand, by setting the wire diameter of the mesh-shaped sheet 14 to be equal to or less than the above upper limit, it is possible to prevent the opening size from becoming too small and perform more efficient dehydration.

As described above, the CNF slurry 15 is filled in the mold 11 in which the paper 13 and the mesh sheet 14 are sequentially laminated on the bottom. The slurry 15 contains CNF and water as a dispersion medium, and may further contain other components.

The content of CNF in the slurry 15 to be subjected to the preliminary dehydration step is preferably more than 0.8% by mass, more preferably 1% by mass or more, still more preferably 1.5% by mass or more. By setting the CNF content in the slurry to more than 0.8% by mass, the outflow of CNF in the preliminary dehydration step can be more sufficiently suppressed. In addition, the time required for the preliminary dehydration step can be shortened. Further, when the CNF content is 0.8% by mass or less, the fluidity is high even without pressurization, and CNF may flow out from the mesh-like sheet during filling, but the content should be more than 0.8% by mass. Therefore, such an inconvenience can be eliminated. On the other hand, the upper limit of the CNF content is, for example, 10% by mass, 5% by mass, 4% by mass, or 3% by mass. By setting the content of CNF in the slurry 15 to the above upper limit or less, good fluidity can be ensured and the filling property into the mold 11 can be improved. Further, by setting the CNF content to the above upper limit or less, unevenness in thickness and density can be suppressed, and a highly uniform molded product can be obtained.

A plate-shaped lid 16 is laminated on the slurry 15 filled in the mold 11. The length and width of the lid 16 are substantially the same as or one size smaller than the inner dimensions of the mold 11. The slurry 15 is substantially sealed in a space composed of a lid 16, a formwork 11, and a table (not shown) on which the formwork 11 is placed. That is, the outer surface shape of the molded body (plate-shaped body) from which the upper surface of the table and the inner surface shapes of the mold 11 and the lid 16 can be obtained.

The material of the lid 16 is not particularly limited, and examples thereof include metal, resin, and wood, but metal is preferable from the viewpoint of durability against high pressure and the like. The material of the lid 16 may be the same as or different from the material of the mold 11.

(Preparation process)
The manufacturing method may have a preparatory step of preparing the state of FIG. 2 before performing the preliminary dehydration step. This preparatory step is a step of laminating the paper 13 and the mesh sheet 14 in order on the bottom of the mold 11 placed on the table so as to be in the state of FIG. 2, and filling the slurry 15 on the paper 13 and the mesh sheet 14 in order. .. Further, the lid 16 is arranged on the slurry 15 after filling. As will be described later, if dehydration starts at the stage where the slurry 15 is filled, the lid 16 does not have to be placed on the slurry 15 at this timing.

Further, the production method may have a slurry preparation step containing CNF as a preparatory step, or may have a mixing step of CNF and the fiber.

(Preliminary dehydration process)
Hereinafter, the procedure of the preliminary dehydration step will be described in detail. In this pre-dewatering step, it is preferable to increase the pressing force on the slurry 15 stepwise or continuously. In this dehydration step, the water in the slurry 15 flows out from the bottom (lower side in FIG. 2) of the mold 11 via the mesh sheet 14 and the paper 13. In this case, since the initial pressure is very weak, the slurry 15 is maintained at a high viscosity, and the outflow of CNF can be suppressed. On the other hand, as the dehydration progresses, the concentration of the slurry 15 increases and the fluidity decreases, so that the CNF does not easily flow out even if the pressure is increased to some extent. Therefore, by gradually increasing the pressure, dehydration can be efficiently performed while suppressing the outflow of CNF.

The pre-dehydration step preferably includes an initial step of pressurizing at 2.5 kPa or less. When a pressure exceeding 2.5 kPa is initially applied, CNF tends to flow out through the mesh sheet 14. If the mesh-like sheet 14 having a fine opening is used, the outflow of CNF can be suppressed even if a pressure exceeding 2.5 kPa is applied at the initial stage, but in this case, the overall dehydration efficiency may be lowered. The pressurization in this initial step may be substantially 0 kPa or atmospheric pressure. Further, the pressure may be applied only by the weight of the lid body 16. For example, when water flows out through the mesh sheet 14 (when dehydration starts) when the CNF 15 is charged (filled) into the mold 11 via the paper 13 and the mesh sheet 14, in this state. After leaving it for a while, the lid 16 can be placed on the slurry 15 when the outflow of water has subsided.

It is preferable to increase the pressing force after dehydration has progressed to some extent by the pressurization in the initial step. The method for controlling the pressing force is not particularly limited, and may be controlled by a known press machine, or may be performed by placing a weight on the lid body 16. Further, the pressing force may be increased according to the progress of dehydration (dehydration amount), or the relationship between the composition of the slurry 15 and the pressing force may be stored in a database and the pressing force may be controlled according to the time. good.

In the preliminary dehydration step, it is preferable to increase the pressing force in this way and pressurize at 20 MPa or more, more preferably 30 MPa or more, still more preferably 40 MPa or more as the final step. By going through this final step, a plate-like body that has been sufficiently dehydrated can be obtained. The upper limit of the pressing force in this final step can be, for example, 200 MPa, or 100 MPa.

In addition, unlike FIG. 2, a second mesh-like sheet is laminated on the upper surface of the slurry 15, a second paper is laminated on the upper surface of the second mesh-like sheet, and a lid is attached to the upper surface of the second paper. The body 16 may be placed. By laminating paper on the upper surface side of the slurry 15 in this way (the state of sandwiching the slurry 15 with a pair of papers), the cushioning property is further enhanced and the CNF flows out due to pressurization. Can be further suppressed. Further, the paper may be laminated only on the upper surface side of the slurry 15. The second mesh-like sheet laminated on the upper side plays a role of preventing the slurry 15 and the second paper from coming into direct contact with each other. That is, since the CNF plate-like body has a high affinity with paper, when the slurry and the paper are in direct contact with each other and the paper is pressurized and dehydrated, the paper sticks to the obtained CNF plate-like body, and this paper is attached. It becomes difficult to peel off. Therefore, by laminating a mesh-like sheet between the slurry and the paper, the paper or the like can be easily peeled off from the obtained CNF plate-like body. Further, since the water content in the slurry is transferred to the paper via the mesh-like sheet, the dehydration efficiency can be improved.

Further, in the preliminary dehydration step of FIG. 2, dehydration is performed only by pressurization without heating, but the preliminary dehydration step may be performed while heating.

(Pressurization process)
In the pressurizing step, the plate-like body containing CNF and water obtained by the preliminary dehydration step is pressurized in the thickness direction while being heated. This pressurizing step includes a first pressurizing step of pressurizing the plate-like body in a direction perpendicular to the thickness direction (horizontal direction when pressurizing in the vertical direction), and the first pressurizing step. A second pressurizing step of compressing the plate-like body in the thickness direction with a higher pressure is provided in this order. The pressurizing step has at least two steps, and the first pressurizing step may be made into a plurality of steps or the second pressurizing step may be made into a plurality of steps so that the degree of pressurization is gradually increased. Is also possible. Further, the third pressurizing step may be performed. Hereinafter, preferred embodiments to be performed in two steps (one-step first pressurization step and one-step second pressurization step) will be described.

In the pressurizing step, as shown in FIG. 3, a plate-shaped body 27 containing CNF and water is arranged between a pair of upper and lower heating plates 21 and 22. The mesh-shaped sheets 25 and 26 are laminated on both surfaces of the plate-shaped body 27, and the porous sheets 23 and 24 are laminated on the outer surfaces of the mesh-shaped sheets 25 and 26. That is, between the pair of horizontally arranged heating plates 21 and 22, the first porous sheet 23, the first mesh-like sheet 25, the plate-like body 27, and the second mesh-like sheet 26 are arranged in this order from the bottom. And the second porous sheet 24 are laminated. Further, all the side surfaces of the plate-shaped body 27 are exposed.

The heating plates 21 and 22 are arranged horizontally and parallel to each other. The heating plates 21 and 22 are heating plates (hot plates) provided in a general heat press machine (heating press machine). That is, this heating step can be performed using a conventionally known hot press machine. While the heating plates 21 and 22 are being heated, a force acts in a direction in which the distance between the pair of heating plates 21 and 22 is narrowed, so that the plate-shaped body 27 is heated in the thickness direction (vertical direction in FIG. 3). Is pressurized to. The heat press can control the heating temperature and the pressurizing pressure. The temperature control and pressure control by the heat press machine may be automatic control or manual control. Further, the heat press machine is not particularly limited to a hydraulic heat press machine, a pneumatic heat press machine, a vise heat press machine and the like.

The pair of porous sheets 23 and 24 are arranged in a state where the plate-shaped body 27 is sandwiched between the mesh-shaped sheets 25 and 26, respectively.

As the mesh-like sheets 25 and 26, those having the same type and shape as the mesh-like sheet 14 used in the preliminary dehydration step can be used. The mesh-like sheet used in the pre-dehydration step may be used as it is or may be replaced with another one, but from the viewpoint of workability, it is preferable to use the mesh-like sheet used in the pre-dehydration step as it is. ..

The porous sheets 23 and 24 are not particularly limited as long as they are porous sheets, and are inorganic porous sheets made of inorganic particles such as zeolite, fiber porous sheets, and sponge porous sheets. Various porous sheets such as sheets can be used. Among these, a porous fiber sheet is preferable from the viewpoint of cushioning property and the like. Fibers constituting the fiber porous sheet include plant fibers such as pulp, cotton fiber, silk fiber and hemp; animal fiber such as wool and animal hair; synthetic fiber such as nylon fiber, polyester fiber and acrylic fiber; glass. Fiber; carbon fiber and the like can be mentioned. Further, the porous sheet made of fiber may be a woven fabric, a non-woven fabric or the like.

Among these, as the porous sheets 23 and 24, a non-woven fabric formed from plant fibers is preferable, and a non-woven fabric formed from pulp, specifically paper, is more preferable from the viewpoint of heat resistance and the like. When paper is used as the porous sheets 23 and 24, the same type and shape as the paper used in the preliminary dehydration step can be used. However, in order to promote the dehydration of the plate-shaped body 27, it is preferable to replace the paper used in the preliminary dehydration step and use the dried new paper as the porous sheets 23 and 24.

The lower limit of the thickness of each of the porous sheet 23 and the porous sheet 24 is, for example, 0.05 mm, preferably 0.1 mm. By setting the thickness of the porous sheets 23 and 24 to the above lower limit or more, a particularly sufficient discharge route of water vapor at the time of heating can be secured, and effective drying can be performed. On the other hand, the upper limit of this thickness is, for example, 2 mm. The thickness of each of the porous sheet 23 and the porous sheet 24 is such that when a plurality of porous sheets are laminated and used as the porous sheet 23 or the porous sheet 24, the plurality of porous sheets in the laminated state are used. The thickness of the quality sheet 23 or the entire porous sheet 24.

Further, by laminating the porous sheets 23 and 24, the water content in the plate-shaped body 27 is transferred to the porous sheets 23 and 24, so that the dehydration efficiency can be improved. When the thickness of the porous sheets 23 and 24 is equal to or greater than the above upper limit, the amount of water transferred to the porous sheets 23 and 24 returns to the plate-shaped body 27 after the pressure is released, so that the efficiency of dehydration is improved. It will decrease. From the viewpoints of air permeability, cushioning property and dehydration property, the porous sheets 23 and 24 preferably have a low density. Further, from the viewpoint of dehydration, the porous sheets 23 and 24 are preferably low in size. From this point of view, filter paper can be preferably used as the porous sheets 23 and 24.

(1st pressurization step)
The first pressurizing step is a step of pressurizing the plate-shaped body 27 in a direction perpendicular to the thickness direction (horizontal direction in FIG. 3, usually horizontal direction) within a range that does not deform.

The upper limit of the water content of the plate-shaped body 27 to be subjected to the first pressurizing step is preferably 90% by mass, more preferably 80% by mass, and may be 70% by mass, or 60% by mass. May be. By setting the water content of the plate-shaped body 27 to be subjected to the first pressurizing step, that is, before the pressurizing step to the above upper limit or less, the spread of the plate-shaped body 27 in the surface direction at the time of pressurization is more reliable. It can be suppressed with high sex. On the other hand, as the lower limit of the water content, 40% by mass is preferable, and 50% by mass is more preferable. When the water content of the plate-shaped body 27 subjected to the first pressurizing step is lower than the above lower limit, dehydration in the preliminary dehydration step is particularly sufficient. The pre-dehydration step may be performed while heating, but heating may be uneconomical due to the time and energy loss required for heat conduction of the mold. Therefore, it is preferable to dehydrate to the above lower limit or more, which can be mechanically dehydrated relatively easily only by pressurization without heating.

As the lower limit of the pressing force in the first pressurizing step, 1 MPa is preferable, and 3 MPa is more preferable. By setting the pressing force in the first pressurizing step to the above lower limit or higher, dehydration can be promoted while maintaining the smoothness and homogeneity of the plate-shaped body 27, and deformation in the thickness direction due to aggregation of CNF is also suppressed. can. On the other hand, the pressing force in the first pressurizing step is preferably less than 10 MPa, more preferably 5 MPa or less. By setting the pressing force in the first pressurizing step to be equal to or lower than the above upper limit, it is possible to suppress the spread of the plate-shaped body 27 in the surface direction during pressurization with higher certainty. Further, by setting the pressing force in the first pressurizing step to be equal to or lower than the above upper limit, a certain amount of water can be left after the first pressurizing step. By performing the second pressurizing step, which is a subsequent step, in such a state, effective compression is generated in the second pressurizing step, and a higher density molded product can be obtained. That is, in other words, if the pressing force in the first pressurizing step is too high, the remaining water content may be too small, and sufficient compression may not occur in the second pressurizing step.

As the lower limit of the treatment temperature in the first pressurizing step, 100 ° C. is preferable, and 110 ° C. is more preferable. On the other hand, as the upper limit of this treatment temperature, 150 ° C. is preferable, 140 ° C. is more preferable, and 130 ° C. is further preferable. Further, the lower limit of the processing time in the first pressurizing step is preferably 10 minutes. On the other hand, the upper limit of this processing time is preferably 30 minutes, more preferably 20 minutes. By performing the first pressurizing step at the above treatment temperature and treatment time, sufficient drying is performed to such an extent that spreading in the surface direction is unlikely to occur even when the pressing force is increased in the second pressurizing step which is a subsequent step. Can be done. Further, by setting the treatment temperature and the treatment time as such, a certain amount of water can be left in the plate-shaped body 27. Due to the presence of this residual water, hydrogen bonds between CNFs due to the presence of water are effectively generated in the second pressurizing step, the number of hydrogen bond points per unit volume increases, and the obtained CNF molded product has a higher density. It can be increased in strength and strength.

(Second pressurization step)
The second pressurizing step is a step of compressing the plate-shaped body 27 in the thickness direction by a pressure higher than that of the first pressurizing step. The spread of the plate-shaped body 27 in the plane direction in this second pressurizing step is sufficiently suppressed. Although the first pressurizing step and the second pressurizing step can be continuously performed, it is preferable to provide a stepwise pressure difference between the first pressurizing step and the second pressurizing step. By continuously and stepwise performing while providing a pressure difference, for example, the second pressurizing step can be performed while maintaining the heated state, and the drying efficiency can be high and the density can be further increased. ..

As the lower limit of the pressing force in the second pressurizing step, 10 MPa is preferable, and 12 MPa is more preferable. By setting the pressing force in the second pressurizing step to be equal to or higher than the above lower limit, the plate-shaped body 27 is sufficiently compressed in the thickness direction, and a CNF molded body having particularly excellent strength can be obtained. On the other hand, the upper limit of the pressing force in the second pressurizing step may be, for example, 50 MPa, 30 MPa, or 20 MPa. By setting the pressing force in the second pressurizing step to be equal to or lower than the above upper limit, it is possible to suppress the spread of the plate-shaped body 27 in the surface direction during pressurization with higher certainty.

The processing temperature in the second pressurizing step may be the same as that in the first pressurizing step. Further, the processing time in the second pressurizing step is not particularly limited, and may be terminated when further compression does not proceed or further drying does not proceed.

(Post-process)
By going through the above pressurization step, a CNF molded product can be obtained. After the pressurizing step, a further step such as a cooling step or a humidity control step may be provided.

(Advantages of the manufacturing method, etc.)
In the manufacturing method, the water in the plate-shaped body 27 is released as water or water vapor from the side surface of the plate-shaped body 27 during the pressurizing step. Further, since the plate-shaped body 27 is sandwiched between the mesh-shaped sheets 25 and 26 and the porous sheets 23 and 24, water is also released from the upper surface and the lower surface of the plate-shaped body 27. According to the manufacturing method, in the first pressurizing step, the plate-shaped body 27 is pressed so weakly that the plate-shaped body 27 is not deformed in the direction perpendicular to the thickness direction (plane direction) while being heated. It is possible to proceed with drying while suppressing the deformation of. In addition, after drying to some extent in this first pressurizing step, compression is performed in the thickness direction by high pressure in the second pressurizing step, so that the direction is perpendicular to the thickness direction (plane direction). It is possible to obtain a high-density and high-strength CNF molded product in which the spread of the material is minimized.

Further, by performing the pressurizing step in a state where the plate-shaped body 27 is sandwiched between the pair of porous sheets 23 and 24, the water vapor generated during heating is discharged through the porous sheets 23 and 24 and effectively dried. It can be performed. Further, when the plate-shaped body 27 contains pulp, the cohesiveness is lowered as compared with the case of only CNF, so that a high-strength molded body can be obtained by pressurizing in two steps. The advantages of can be enjoyed more effectively.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

<Evaluation method>
The following various physical properties were measured according to the following evaluation method.

(Pseudo particle size distribution curve)
In accordance with ISO-13320 (2009), a curve showing a volume-based particle size distribution was measured using a particle size distribution measuring device (HORIBA, Ltd. particle size distribution measuring device "LA-960S").

(Water retention (%))
The water retention rate (%) of the cellulose nanofibers is determined by JAPAN TAPPI No. Measured according to 26: 2000.

(Elastic modulus (MPa))
The elastic modulus of the CNF molded product was measured and calculated under the following conditions (25 ° C. or 90 ° C.) by the nanoindentation method based on ISO14577.

(Hardness (MPa))
The hardness of the CNF molded product was measured and calculated under the following conditions (25 ° C.) by the nanoindentation method based on ISO14577.

[Measurement conditions for nanoindentation method]
Equipment: Hysiron Inc. Triboindenter
Indenter: Berkovich (triangular pyramid type)
Temperature: 25 ° C or 90 ° C
Pushing load: 100 mN (Examples and reference examples)
Pushing depth: 500 nm (comparative example)
Pushing speed: 20 mN / sec. (Examples and reference examples)
Pushing speed: 100 nm / sec. (Comparative example)

(Tension modulus (MPa))
The tensile modulus of elasticity of the CNF molded product was measured according to JIS K7127: 1999. The test piece had a tension type 2 dumbbell shape defined by JIS-K6251. The test speed was 10 mm / min. Further, the measurement was carried out in an environment of a temperature of 23 ° C. or 90 ° C.

(Tensile strength (MPa))
The tensile strength of the CNF molded product was measured according to JIS K7127: 1999. The test piece had a tension type 2 dumbbell shape defined by JIS-K6251. The test speed was 10 mm / min. Moreover, the measurement was performed in an environment of a temperature of 23 ° C.

(Tensile fracture strain (MPa))
The tensile fracture strain of the CNF compact was measured according to JIS K7127: 1999. The test piece had a tension type 2 dumbbell shape defined by JIS-K6251. The test speed was 10 mm / min. Moreover, the measurement was performed in an environment of a temperature of 23 ° C.

(density)
The density of the CNF compact was measured according to JIS-P-8118 (1998).

[Manufacturing example]
The raw material pulp (LBKP) was refined as a preliminary beat and then defibrated (miniaturized) with a high-pressure homogenizer to obtain a CNF slurry (aqueous dispersion: concentration 2.2% by mass). In both the refiner treatment and the high-pressure homogenizer treatment, a circulation treatment was performed a plurality of times. The CNF contained in the obtained slurry had one peak in the pseudo particle size distribution of the particle size distribution measurement using laser diffraction (mode 45 μm), and the water retention degree was 343%.

[Example 1]
(Preparation process)
A slurry having a solid content concentration of 2.3% by mass was prepared by mixing CNF using LBKP as a raw material obtained in the production example and pulp (LBKP: unbeaten pulp) at a mass ratio of 80:20. As the pulp, unbeaten pulp (LBKP) having a concentration of 21.6% by mass and a freeness of 580 mL was used.

Paper 13 was laid on the bottom of the rectangular metal formwork 11 shown in FIG. 2, and then a mesh-like sheet 14 was laid. Both the paper 13 and the mesh-shaped sheet 14 were used in the same size as the bottom surface of the mold 11. As the paper 13, a filter paper having a thickness of 0.28 mm was used. As the mesh-like sheet, a sheet made of SUS316 having a mesh number of 300 meshes and a wire diameter of 40 μm was used. Next, the obtained mixed slurry of CNF and pulp is filled in the mold 11, and a mesh sheet, paper and a metal plate-shaped lid 16 (bottom area 0.067 m ² , mass) are placed thereon. 8.0 kg) were placed in this order. The mesh-like sheet and paper stacked on the slurry are the same as the previously laid mesh-like sheet and paper.

(Preliminary dehydration process)
Due to the weight of the placed lid 16, the slurry 15 was pressurized at 1.2 kPa and water began to flow out from the bottom (dehydration was started). It was visually confirmed that this water was transparent and that CNF did not flow out. Pressurization by the weight of the lid 16 was set as the initial step.

After that, at the timing when the outflow of water weakened, a weight was placed on the lid 16 to increase the pressing force. Finally, the slurry 15 was pressurized at 50.0 MPa to complete the final step. The total dehydration time from the initial step to the final step was 60 minutes. As a result, a plate-like body dehydrated to a water content of 54.2% was obtained. It was visually confirmed that CNF did not flow out from the initial process to the final process.

(Pressurization process)
Using the obtained plate-shaped body and a general-purpose heat press machine, the set was set in the state shown in FIG. As the porous sheets 23 and 24, new dried paper similar to the paper used in the preliminary dehydration step was used. As the mesh-shaped sheets 25 and 26, those used in the preliminary dehydration step were used as they were.

As the first pressurizing step, pressurization was performed at a pressure of 50 kgf / cm ² (4.9 MPa) and a temperature of 120 ° C. for 15 minutes. Then, as a second pressurizing step, pressurization was performed at a pressure of 150 kgf / cm ² (14.7 MPa) and a temperature of 120 ° C. As a result, the plate-shaped body was compressed in the thickness direction to obtain the CNF molded body of Example 1. The obtained CNF molded product did not spread in the plane direction and maintained a rectangular shape in a plan view.

The elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method of the obtained CNF molded product was 9.0 × 10 ³ MPa, and the elastic modulus (E) at 90 ° C. calculated by the nanoindentation method. ₉₀ ) was 7.6 × 10 ³ MPa, and the nanoindentation hardness was 4.6 × 10 ² MPa. The ratio (E ₉₀ / E ₂₅ ) was 0.84. The density of the obtained CNF molded product was 1.29 g / cm ³ .

[Example 2]
A CNF molded product was obtained by the same method as in Example 1 and subjected to a tensile test. The tensile elastic modulus (T ₂₃ ) of the obtained CNF molded product at 23 ° C. was 16.3 × 10 ³ MPa, and the tensile elastic modulus (T ₉₀ ) at 90 ° C. was 12.0 × 10 ³ MPa. The strength was 1.1 × 10 ² MPa, and the tensile fracture strain was 1.8%. The ratio (T ₉₀ / T ₂₃ ) was 0.74. The density of the obtained CNF molded product was 1.19 g / cm ³ .

[Reference Example 1]
Only CNF using LBKP obtained in Production Example as a raw material was used, and a CNF molded product was obtained by the same method as in Example 1. The elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method of the obtained CNF molded product was 9.4 × 10 ³ MPa, and the elastic modulus (E) at 90 ° C. calculated by the nanoindentation method. ₉₀ ) was 8.4 × 10 ³ MPa, and the nanoindentation hardness was 3.7 × 10 ² MPa. The ratio (E ₉₀ / E ₂₅ ) was 0.90. The tensile elastic modulus (T ₂₃ ) of the obtained CNF molded product at 23 ° C. was 18.4 × 10 ³ MPa, and the tensile elastic modulus (T ₉₀ ) at 90 ° C. was 12.6 × 10 ³ MPa. ^The tensile strength was 1.5 × 102 MPa, and the tensile fracture strain was 1.9%. The ratio (T ₉₀ / T ₂₃ ) was 0.68. The density of the obtained CNF molded product was 1.33 g / cm ³ .

[Example 4]
A CNF molded product was obtained by the same method as in Example 1 except that CNF using LBKP as a raw material obtained in Production Example and pulp (LBKP: beaten pulp) were mixed at a mass ratio of 30:70. The elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method of the obtained CNF molded product was 3.3 × 10 ³ MPa, and the elastic modulus (E) at 90 ° C. calculated by the nanoindentation method. ₉₀ ) was 2.3 × 10 ³ MPa, and the nanoindentation hardness was 0.9 × 10 ² MPa. The ratio (E ₉₀ / E ₂₅ ) was 0.70. The tensile elastic modulus (T ₂₃ ) of the obtained CNF molded product at 23 ° C. was 9.6 × 10 ³ MPa, and the tensile elastic modulus (T ₉₀ ) at 90 ° C. was 7.8 × 10 ³ MPa. ^The tensile strength was 0.7 × 102 MPa, and the tensile fracture strain was 1.0%. The ratio (T ₉₀ / T ₂₃ ) was 0.81. The density of the obtained CNF molded product was 1.07 g / cm ³ .

[Example 5]
CNF made from LBKP obtained in Production Example and pulp (LBKP: unbeaten pulp) are mixed at a mass ratio of 80:20, and the production conditions are changed from Example 1 to obtain molded bodies having different densities. rice field. The elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method of the obtained CNF molded product was 4.2 × 10 ³ MPa, and the elastic modulus (E) at 90 ° C. calculated by the nanoindentation method. ₉₀ ) was 3.8 × 10 ³ MPa, and the nanoindentation hardness was 1.7 × 10 ² MPa. The ratio (E ₉₀ / E ₂₅ ) was 0.92. The tensile elastic modulus (T ₂₃ ) of the obtained CNF molded product at 23 ° C. was 14.5 × 10 ³ MPa, and the tensile elastic modulus (T ₉₀ ) at 90 ° C. was 10.6 × 10 ³ MPa. ^The tensile strength was 1.0 × 102 MPa, and the tensile fracture strain was 1.1%. The ratio (T ₉₀ / T ₂₃ ) was 0.73. The density of the obtained CNF molded product was 0.95 g / cm ³ .

[Comparative Examples 1 to 3]
For polypropylene (PP) film (Comparative Example 1), PP dumbbell test piece (Comparative Example 2), and aluminum foil (Comparative Example 3), the elastic modulus (E ₂₅ ) calculated by the nanoindentation method was similarly measured. .. The measured values are shown in Table 1. "-" In the table indicates that the measurement has not been performed.

As shown in Table 1, it can be seen that the CNF molded product of Example 1 has a high elastic modulus and this temperature dependence is small. Further, it can be seen that these CNF compacts have high hardness, tensile elastic modulus and tensile strength, and have small tensile fracture strain.

The CNF molded body of the present invention is excellent in strength, thermal stability, etc., and can be used as a material or the like in place of a metal molded body, a resin molded body, wood, or the like.

11 Formwork 13 Paper 14 Mesh sheet 15 Slurry 16 Lid 21, 22 Heating plate 23, 24 Porous sheet 25, 26 Mesh sheet 27 Plate

Claims (4)

The main component is cellulose fiber containing cellulose nanofiber.
The cellulose fibers further contain pulp and
The content of pulp in the cellulose fibers is 0.1% by mass or more and 70% by mass or less.
The elastic modulus (E ₂₅ ) at 25 ° C. calculated by the nanoindentation method is 3,000 MPa or more and 20,000 MPa or less.
The ratio (E ₉₀ / E ₂₅ ) of the elastic modulus (E ₉₀ ) at 90 ° C. calculated by the nanoindentation method to the elastic modulus (E ₂₅ ) at 25 ° C. is 0.5 or more .
A cellulose nanofiber molded body having a single peak in a pseudo particle size distribution curve in which the cellulose nanofibers are measured by a laser diffraction method in an aqueous dispersion state . The cellulose nanofiber molded product according to claim 1, wherein the pulp is beaten. The cellulose nanofiber molded product according to claim 1 or 2, wherein the content of the cellulose nanofibers in the cellulose fibers is 50% by mass or more. The cellulose nanofiber molded product according to claim 1, claim 2 or claim 3, wherein the density is 0.95 g / cm ³ or more and 1.5 g / cm ³ or less.

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