JP7385576B2 - Structure - Google Patents

Description

The present invention relates to a structure containing cellulose nanofibers.

Attempts have been made to use cellulose nanofibers (CNF) for various purposes, and as one example, a porous body made of CNF has been proposed (see, for example, Patent Document 1). As a method for producing a porous body of CNF, a method including a step of freeze-drying a water slurry in which CNF is uniformly dispersed at a low temperature is widely known. The porous body obtained by freeze-drying has a so-called open cell structure, and is expected to be used as an adsorbent, a heat insulating material, a sound absorbing material, etc.

Japanese Patent Application Publication No. 2010-215872

In order to promote the use of CNF and further expand its applications, there is a need for a structure containing CNF that has a new structure that cannot be obtained by conventional manufacturing methods. For example, there is a need for a structure suitable for use in retaining fluid within the structure and extracting the fluid outside the structure when necessary. A structure suitable for such uses is required to have a strength capable of stably retaining fluid and a structure capable of retaining as much fluid as possible.

An object of the present invention is to provide a structure that includes a membrane containing cellulose nanofibers and a plurality of closed spaces made up of the membrane, has a large proportion of spaces, and has a high strength structure. .

As a result of intensive studies to solve the above problems, the present inventors have developed a structure that includes a plurality of closed spaces made of a membrane containing cellulose nanofibers, and in which the size of the plurality of closed spaces is small. As a result, they discovered that it is possible to create a structure with a large proportion of space and high strength, and have completed the present invention.
That is, the present invention provides the following [1] to [12].
[1] A structure comprising a membrane containing cellulose nanofibers and a plurality of closed spaces formed from the membrane, wherein the average maximum Feret diameter of the plurality of closed spaces in a cross section of the structure is 1 μm. The structure is ~60 μm.
[2] The structure according to [1] above, wherein a pair of adjacent closed spaces among the plurality of closed spaces share at least one of the membranes.
[3] The structure according to [1] or [2] above, wherein the film containing cellulose nanofibers has an average thickness of 10 nm to 2000 nm.
[4] The structure according to any one of [1] to [3] above, wherein the structure has a bulk density of 0.001 to 1.4 g/cm ³ .
[5] The structure according to any one of [1] to [4] above, wherein the structure has a sheet shape.
[6] The structure according to [5] above, wherein the structure has a thickness of 0.5 to 300 μm.
[7] In the cross section of the structure in the thickness direction, the maximum length of the closed space in the thickness direction of the structure is a, and the maximum length of the closed space in the planar direction of the structure is b. The structure according to [5] or [6] above, wherein the average b/a of the plurality of closed spaces is greater than 1.
[8] The structure according to any one of [1] to [7] above, wherein the cellulose nanofiber is a plant-derived cellulose nanofiber.
[9] The structure according to any one of [1] to [8] above, wherein the content of polysaccharides other than the cellulose nanofibers is less than 10 parts by mass based on 100 parts by mass of the cellulose nanofibers. body.
[10] The structure according to any one of [1] to [9] above, wherein the cellulose nanofibers have an average diameter (thickness) of 1 to 1000 nm.
[11] The structure according to any one of [1] to [10] above, wherein the cellulose nanofibers have an average fiber length of 0.01 to 10 μm.
[12] A structure with a support, in which the structure according to any one of [1] to [11] above is provided on a support.

According to the present invention, it is possible to provide a structure that includes a membrane containing cellulose nanofibers and a plurality of closed spaces made up of the membrane, has a large proportion of spaces, and has a high strength structure. .

FIG. 1 is a schematic diagram showing the configuration of a sheet-like structure that is an embodiment of the structure of the present invention. FIG. 1(A) is a partial cross-sectional view of the sheet-like structure in the thickness direction, FIG. 1(B) is an enlarged view of a part of FIG. 1(A), and FIG. 1(C) is a partial cross-sectional view of the sheet-like structure in the thickness direction. It is a figure explaining the size of a closed space. FIG. 2 is a schematic side view showing a composition applied onto a support. It is a SEM image of the cross section in the thickness direction of the sheet-like structure produced in Example 6.

<Structure structure>
A structure according to an embodiment of the present invention is a structure including a membrane containing cellulose nanofibers (CNF) and a plurality of closed spaces configured from the membrane, the structure including a plurality of closed spaces in a cross section of the structure. The average maximum Feret diameter of the closed space is 1 μm to 60 μm. The maximum Feret diameter and its average will be detailed later.
As used herein, "a closed space constituted by a membrane containing CNF" means a closed space surrounded in all directions, such as above, below, and on the sides, by a membrane containing CNF. Note that, as described later, a film containing CNF is a dense film but has fine voids. Therefore, if the space surrounded by the CNF-containing film does not communicate with an opening larger than the above-mentioned micropores, it corresponds to a "closed space constituted by a CNF-containing film."
The shape of the structure is not particularly limited, and can be formed into any shape by, for example, placing the composition described below in a mold and drying it. A preferred embodiment of the structure of the present invention is a sheet-like structure. The sheet-like structure can be easily produced in large quantities by applying the composition described below on a support and drying, and can be used for a wide variety of purposes. Hereinafter, a structure according to an embodiment of the present invention will be specifically described using the drawings, taking a sheet-like structure as an example. Note that FIGS. 1 and 2 used in the following description are schematic diagrams, and are illustrated in an exaggerated manner for easy understanding. The number and size of closed spaces, the thickness of the structure, etc. are also shown schematically, and these are not limited by the drawings.

FIG. 1(A) is a schematic partial cross-sectional view in the thickness direction of a sheet-like structure that is an embodiment of the structure of the present invention. As shown in FIG. 1A, a layer 31 provided on a support 40 and having a plurality of closed spaces 33 made of a membrane 35 containing CNF constitutes a sheet-like structure. The layer 31, which is a sheet-like structure, and the support 40 constitute a sheet-like structure 50 with a support. Note that, as described later, the support body 40 may not be provided. If there is no support body 40, the sheet-like structure 31 will be a single unit.
The CNF-containing film 35 formed by the manufacturing method described below is considered to be a dense mesh-like or fibrous film formed by a plurality of CNFs being lined up or intertwined. Therefore, for example, the sheet-like structure 31 or the sheet-like structure 50 with a support can be applied to a product that retains a fluid in a closed space 33 surrounded by a membrane 35 containing CNF. Such products (hereinafter sometimes referred to as "fluid holding products") can supply fluid to the outside by applying pressure to rupture the structure when necessary.
In addition, since the membrane 35 containing CNF is a dense membrane of CNF, it has a certain strength even without making the membrane thick, and can form a closed space that can hold fluid inside. can. Therefore, elements other than the CNF-containing film, such as a binder component, are not necessarily required inside the structure, and the proportion of space in the structure can be increased.
Furthermore, a membrane containing CNF has many minute voids, and can allow fluids such as gas and liquid to permeate little by little. Therefore, for example, the sheet-like structure 31 or the sheet-like structure 50 with a support may be used as a product that retains fluid in the closed space 33 and gradually releases the fluid to the outside through the membrane 35 containing CNF. Can be applied. Hereinafter, the property of gradually releasing fluid to the outside through a membrane will be referred to as sustained release.
In addition, in addition to the complicated process of the conventional manufacturing method using freeze-drying, the resulting porous body has a so-called open cell structure. A porous body having such an open cell structure is not suitable for retaining a fluid, and is difficult to apply to the above-mentioned fluid retaining products or products having sustained release properties.

FIG. 1(B) is an enlarged view of a portion surrounded by a dashed line in FIG. 1(A). As shown in FIG. 1(B), in the sheet-like structure 31 and the sheet-like structure 50 with a support, the membrane 35a containing CNF is shared between a pair of adjacent closed spaces 33a and 33b. ing. In a preferred embodiment of the structure of the present invention, as in the sheet-like structure 31 and the sheet-like structure 50 with a support, a set of adjacent closed spaces among the plurality of closed spaces has at least one membrane. share.
Note that in the cross section of the film containing CNF, a boundary formed along the film containing CNF may be observed. In the sheet-like structure of this embodiment, the film containing CNF may include such a boundary. It is presumed that the above-mentioned boundary reflects the difference in the state of existence of CNF before it becomes a sheet-like structure, but the presence or absence of this boundary does not particularly affect the properties of the sheet-like structure.

[Maximum Feret diameter of closed space]
Since the above-mentioned closed space can take various shapes, in this specification, the size of the closed space is expressed by the maximum Feret diameter (the size of the closed space does not include the thickness of the film containing CNF). In the structure according to the embodiment of the present invention, the average maximum Feret diameter of the plurality of closed spaces is 1 μm to 60 μm. The lower limit of the average maximum Feret diameter of the plurality of closed spaces is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, particularly preferably 20 μm or more. The average upper limit of the maximum Feret diameters of the plurality of closed spaces is preferably 55 μm or less, more preferably 50 μm or less, even more preferably 45 μm or less, even more preferably 40 μm or less, particularly preferably 35 μm or less.
Here, the "maximum Feret diameter" of a certain figure means the maximum distance of the figure between two parallel lines. In this specification, a shape corresponding to a closed space is specified on a cut plane when a structure including a plurality of closed spaces made of a membrane containing CNF is cut, and two parallel lines are defined for this shape. By measuring the maximum sandwiched distance, the maximum Feret diameter of the closed space is calculated.
The cutting plane for calculating the maximum Feret diameter of the closed space may be appropriately selected so as to include as much of the closed space as possible so that the average maximum Feret diameter can be calculated. In the sheet-like structure 50 with a body, the maximum Feret diameter of the closed space is calculated in the cross section in the thickness direction, as shown in FIG. 1(A). To give a more specific example, the direction tilted with respect to the plane of the sheet-like structure 31 or the sheet-like structure 50 with a support, which exists in the area surrounded by the broken line in FIG. 1(A). In the case of the closed space 33 having the maximum opening width, the maximum Feret diameter df of the closed space 33 matches the maximum opening width, as shown in FIG. 1(C).
In this specification, the "average of the maximum Feret diameters of a plurality of closed spaces" is the average value of the maximum Feret diameters of a plurality of closed spaces in any cut plane of the structure. In this specification, in the above-mentioned cross section of the structure, 36 arbitrary closed spaces are selected, the maximum Feret diameter of each is measured, and the average value thereof is referred to as the "average of the maximum Feret diameters of the plurality of closed spaces". do.

In the structure according to the embodiment of the present invention, the average of the maximum Feret diameters of the plurality of closed spaces in the cross section of the structure is within the above range, and the size of the closed spaces is small. Therefore, a large number of films containing CNF exist inside the structure, and the strength of the structure can be increased. Therefore, it becomes easier to obtain a structure that has excellent shape retention properties against pressurization and the like. In addition, as a result of the increased strength of the structure, it is also advantageous for retaining fluid in a closed space for a long time when the structure is applied to the above-mentioned fluid retention products or products with sustained release properties. work. Furthermore, since the size of the closed spaces is small, it is possible to hold fluids individually in many closed spaces, increasing fluid retention and improving sustained release performance (i.e., over a longer period of time). can be released).
Furthermore, as shown in FIGS. 1(A) and 1(B), the strength of the structure increases when multiple closed spaces share the membrane, so the membrane has self-retention properties without adding a binder component. self-supporting membranes) can be produced. This self-supporting membrane does not necessarily require a binder component, and as compared to, for example, a plurality of capsules each having an internal space bound together with a binder, the space for holding fluid can be increased.

The size of the closed space in the structure can be adjusted, for example, by changing the size of particles having an outer shell containing CNF in the composition described below. Thereby, the maximum Feret diameter of the closed space can be adjusted, and the average of the maximum Feret diameters of the plurality of closed spaces can be kept within the numerical range mentioned above.

[Shape of closed space]
Although the shape of the above-mentioned closed spaces is arbitrary, when a structure is manufactured using the manufacturing method described below, a pair of adjacent closed spaces have a film containing CNF, as described above, due to the manufacturing method. Each closed space has a polyhedral shape surrounded by a plurality of flat membranes so that a shared structure can be easily achieved. Therefore, at least one cut surface having a polygonal shape as shown in FIG. 1 can be formed for each closed space.
Further, in a preferred embodiment of the structure of the present invention, as shown in FIG. , the maximum length in the thickness direction of the closed space of the structure (in other words, the distance from the lowest position to the uppermost position of the surface of the closed space side of the membrane containing CNF) is a, the closed space of the structure When b is the maximum length in the planar direction (in other words, the distance from one end to the other end in the planar direction of the surface of the membrane containing CNF on the closed space side), b/a of the plurality of closed spaces The average of is preferably greater than 1, more preferably greater than 1.5, and still more preferably greater than 2. When the average b/a of the plurality of closed spaces is larger than 1, the closed spaces generally have a shape extending in the plane direction of the structure, so it is possible to provide a large number of closed spaces without increasing the thickness of the structure. . Furthermore, during drying in step (2-3), which will be described later, a closed space extending in the plane direction is likely to be formed due to the weight of the CNF-containing membrane, making it easy to manufacture the structure. The average b/a of the plurality of closed spaces is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, particularly preferably 5 or less, from the viewpoint of ease of manufacture and maintaining the strength of the structure. . In this specification, in the above-mentioned cross section of the structure, 36 arbitrary closed spaces are selected, each of a and b is measured, b/a is calculated, and the average value of these is calculated as "the number of closed spaces of multiple closed spaces." b/a average.

[Average thickness of film containing CNF]
The average thickness of the film containing CNF is preferably 10 nm or more, more preferably 50 nm or more, even more preferably 75 nm or more, and preferably 2000 nm or less, more preferably 1750 nm or less, even more preferably 1500 nm or less, and even more preferably Preferably it is 1250 nm or less. By setting the average thickness of the CNF-containing film to 2000 nm or less, when the structure is applied to a fluid retention product, it becomes easier to cleave the structure by applying pressure and supply the fluid to the outside. Further, when the structure is applied to a product having sustained release properties, it becomes easier to cause sustained release of the fluid in the closed space. Further, by setting the average thickness of the membrane to 10 nm or more, the strength of the entire structure can be increased, and it becomes easier to retain the fluid in the closed space for a long time.
The average thickness of the film containing CNF was determined by observing the cross section of each structure using a scanning electron microscope (SEM), arbitrarily selecting 36 occluded spaces from the obtained enlarged images, and Identify one arbitrary side constituting the polygon corresponding to the space, measure the thickness dm at the approximate center of that side (indicated by two triangular marks and a lead line in Figure 1 (C)), and It is obtained by calculating the average value.
The thickness dm of the film containing CNF can be adjusted, for example, by varying the diameter (thickness) and fiber length of the CNF. A film containing CNFs can be made thicker by increasing the diameter (thickness) of CNFs or shortening the fiber length of CNFs. Conversely, a film containing CNFs can be made thinner by reducing the diameter (thickness) of CNFs or increasing the fiber length of CNFs.

[Bulk density of structure]
The bulk density of the structure is preferably 0.001 g/cm ³ or more, more preferably 0.005 g/cm ³ or more, even more preferably 0.0075 g/cm ³ or more, and still more preferably 0.01 g/cm ³ or more. Yes, and preferably 1.40 g/cm ³ or less, more preferably 1.20 g/cm ³ or less, even more preferably 0.920 g/cm ³ or less, even more preferably 0.800 g/cm ³ or less, even more preferably It is 0.600 g/cm ³ or less, more preferably 0.500 g/cm ³ or less. If the bulk density is 0.001 g/cm ³ or more, it is possible to provide the structure with the minimum necessary strength, for example, it is possible to provide the structure with a strength that does not collapse even when wound into a roll. Further, if the bulk density is 1.40 g/cm ³ or less, it becomes easier to hold a large amount of fluid in the closed space.
In this specification, the bulk density of a structure is calculated by dividing the mass of the structure by the volume of the entire structure including the closed space. As shown in FIG. 1, when a layer containing CNF is formed on a support, the thickness and mass of the support may be measured in advance and calculated after subtracting these values.
The bulk density of the structure can be adjusted, for example, by varying the diameter of the particles with the CNF-containing shell in the composition. In other words, as the diameter of the particles in the composition with the outer shell containing CNF increases, the bulk density decreases, and as the diameter of the particles with the outer shell containing CNF decreases, the bulk density increases. The diameter of the particles having an outer shell containing CNF in the composition can be adjusted by changing the type and blending ratio of the organic solvent or by changing the stirring conditions.

[Structure thickness]
When the structure is sheet-like or strip-like, the thickness L of the structure excluding the support (see FIG. 1(A)) is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 3.5 μm or more, more preferably 5.0 μm or more, particularly preferably 7.5 μm or more, and preferably 300 μm or less, more preferably 200 μm or less, still more preferably 100 μm or less, even more preferably 75 μm or less, especially Preferably it is 50 μm or less. If the thickness of the structure is 300 μm or less, it is possible to avoid long drying times and drying defects, and as a result, it is possible to suppress variations in the shape and size of the closed space, and to reduce the thickness of the structure. It is easy to prevent problems such as deterioration of quality. Further, if the thickness of the structure is 0.5 μm or more, it is easy to prevent the structure from lacking strength or from reducing the amount of fluid that can be held in the closed space.
When the structure is in the form of a sheet or a band, there are no particular restrictions on the area or longitudinal size of the structure, and it can be of any size as long as manufacturing equipment is available. In addition, even when the structure has a shape other than sheet-like or band-like, for example, block-like, the maximum diameter of the structure is preferably 1 mm or more, more preferably 5 mm or more, from the same viewpoint as described above. More preferably 1 cm or more, still more preferably 2.5 cm or more, particularly preferably 5 cm or more, and preferably 5 m or less, more preferably 3 m or less, still more preferably 1 m or less, even more preferably 50 cm or less, particularly preferably It should be 10cm or less.

[Cellulose nanofiber (CNF) and other ingredients]
As for the material, shape, etc. of the CNF constituting the structure, those explained for the CNF added to the composition described below apply as is. In addition, polysaccharides and other components other than CNF that may be contained in the structure (excluding components such as organic solvents that are present in a closed space for the purpose of sustained release) are also included in the composition described below. The same applies. Therefore, a detailed explanation of these will be omitted here.
In addition, when the above-mentioned structure is produced by the production method described below, a composition containing particles having an outer shell containing CNF can be produced without using a dispersant such as a surfactant, and this composition can be used. By doing so, the CNF content in the structure can be increased. Therefore, when the structure of the present embodiment is applied to the above-mentioned fluid retention product or sustained release product, it is possible to prevent unnecessary components from being mixed into the fluid released to the outside. . The surfactant content of the structure is preferably less than 10 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.1 parts by mass, and even more preferably 0.01 parts by mass, based on 100 parts by mass of CNF. part by weight, particularly preferably less than 0.001 part by weight, most preferably 0 part by weight.
In addition, the above-mentioned structure may contain polysaccharides other than CNF, but in the above-mentioned fluid retention products and sustained release products, it is possible to prevent unnecessary components from being mixed into the fluid released to the outside. From the viewpoint of prevention, the content is preferably less than 10 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.1 parts by mass, even more preferably 0 parts by mass, based on 100 parts by mass of the total amount of CNF. It is less than .01 parts by weight, particularly preferably 0 parts by weight.
To measure the content of surfactant in a structure, the surfactant is extracted with a solvent, and the chemical composition is identified using a high performance liquid chromatography mass spectrometer (LC-MS) or nuclear magnetic resonance (NMR). and quantification methods. Moreover, energy dispersive X-ray analysis (EDX) or infrared spectroscopy (IR) can also be used as a means of identification. In the case of EDX, the composition may be directly observed and analyzed. Polysaccharides can also be identified and quantified using the same procedure as surfactants.

[Support]
In one embodiment of the present invention, the structure includes a support, such as a sheet-like structure 50 with a support. When providing a support, the structure and the support may be integrated, or the structure may be separated from the support after the structure is formed. That is, the sheet-like structure may be formed on a temporarily used holder such as a release material.
In the former case, the surface of the support to which the composition is applied is preferably subjected to adhesion-facilitating treatment. As the adhesion-facilitating treatment, for example, corona discharge treatment, plasma treatment, ozone treatment, etc. can be used. Furthermore, an easily adhesive layer can be provided using, for example, acrylic resin, ester resin, urethane resin, or the like. In the latter case, a support with a release layer formed on the surface to which the composition is applied may be used, or a support whose entire structure is made of a material from which the structure can be easily removed may be used.
The support is appropriately selected depending on the use of the sheet-like structure, for example, paper bases such as high-quality paper, art paper, coated paper, glassine paper; these paper bases are laminated with thermoplastic resin such as polyethylene. laminated paper; metal foils such as aluminum foil, copper foil, and iron foil; porous materials such as nonwoven fabrics; polyolefin resins such as polyethylene resin and polypropylene resin; polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin; acetate resin; Examples include resin films or sheets containing one or more resins such as ABS resin, polystyrene resin, and vinyl chloride resin.
The support may be a single layer film or sheet, or a multilayer film or sheet that is a laminate of two or more layers.
Further, the resin film or sheet may be unstretched, or may be stretched in a uniaxial direction or a biaxial direction such as lengthwise or transversely.
Furthermore, the resin film or sheet may contain, in addition to the above-mentioned resins, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, a coloring agent, and the like.
The thickness of the support is appropriately selected depending on the use of the sheet-like structure, but is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and preferably 250 μm or less, more preferably is 200 μm or less, more preferably 150 μm or less.

<Method for manufacturing structure>
A structure having a plurality of closed spaces made of a film containing CNF can be manufactured by a manufacturing method including the following steps (1) and (2) as one embodiment.
- Step (1): A step of adding an organic solvent to an aqueous dispersion of CNF to prepare a composition.
- Step (2): A step of applying the composition onto a support to form a coating film, and drying the coating film to form a sheet-like structure.

Hereinafter, step (1) may be referred to as a "step of preparing a composition" and step (2) as a "step of obtaining a structure." Step (2) includes a step of supplying the composition to one side of the support (step (2-1)) and a step of applying the composition to the support (step (2-2)), as described below. ) and a step of drying the composition applied onto the support (step (2-3)).

FIG. 2 shows one step in the manufacturing process, and is a schematic diagram showing how the composition is applied onto a support. The composition prepared in step (1) contains particles with an outer shell containing CNF, and in steps (2-1) and (2-2), this composition is coated on a support. At this point, as shown in FIG. 2, composition 30 includes particles 32 with a shell containing CNF and a water-based medium 34. Further, the particles 32 contain a liquid mainly composed of an organic solvent, air, or both. After that, in step (2-3), the water and organic solvent are removed by drying, and as shown in FIG. A structure 31 is formed on the support 40.
In addition, when applying the sheet-like structure 31 or the sheet-like structure 50 with a support to the above-mentioned fluid retention products or products with sustained release properties, the sheet-like structure is immersed in a specific liquid to fill the closed space. The above-mentioned liquid can be sealed in the closed space, or a specific type of gas can be sealed in the closed space of the sheet-like structure under a specific gas atmosphere. Furthermore, these fluids may be contained in the closed space during the manufacturing process of the sheet-like structure. For example, a specific type of organic solvent (for example, an organic solvent with a boiling point higher than the drying temperature) may be blended into the composition in advance so that it remains in the closed space 33 even after drying in step (2-3). You can stay there. Alternatively, the composition may be prepared in an atmosphere filled with a specific type of gas, thereby enclosing the fluid in the closed space.

[Step (1): Step of preparing a composition]
In step (1), it is preferable to supply the organic solvent little by little to the aqueous dispersion while stirring the aqueous dispersion.
When CNF is uniformly dispersed in water, an organic solvent is further added, and by dispersing the organic solvent uniformly, the interface between water and organic solvent can be formed without using a dispersant such as a surfactant. The CNFs gather together to form particles with an outer shell containing CNFs. Although the process by which particles having an outer shell containing CNF are formed in the composition is not limited to this, it is presumed that one mechanism is as follows. In other words, since CNF is an insoluble material having amphipathic properties, it creates an energetically stable state by existing at the interface between the water used for emulsification and the organic solvent. In addition, since CNF is insoluble and has film-forming properties, it forms an irreversible independent phase as a result of localization at the interface. It is believed that particles with an outer shell comprising CNF are thus formed in the composition.
It is considered that when an organic solvent is added to an aqueous dispersion containing uniformly dispersed CNF, particles produced by localizing CNF at the interface are relatively stable. For this reason, it is difficult for the produced capsules to change into large-diameter capsules due to bonding with each other, and it is thought that by sufficiently stirring the aqueous dispersion to which the organic solvent has been added, small-diameter and uniform particles can be formed. . It is also possible that air is drawn into the aqueous dispersion by stirring, and then surrounded and fixed by the previously generated stable particles, so that this air is also stably retained (this fixed It is thought that air also becomes bubbles after drying). As a result, it is thought that, in the entire composition, unless excessive stimulation is applied or a constant or higher pressure is intentionally applied, the particles will remain stable and will not disappear for several months or more.

In step (1), from the viewpoint of preventing phase separation of the organic solvent from water without forming particles having an outer shell containing CNF, based on 100 parts by mass of the total amount of the aqueous dispersion, The amount of organic solvent added every 10 seconds is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, and preferably 20 parts by mass. The organic solvent is added in an amount of at most 15 parts by weight, more preferably at most 15 parts by weight, even more preferably at most 10 parts by weight, particularly preferably at most 7 parts by weight. The organic solvent may be supplied continuously or intermittently. In any case, by stirring while adding a limited amount of organic solvent to the aqueous dispersion, the organic solvent is uniformly dispersed in the aqueous dispersion, and as a result, particles with an outer shell containing CNF can be formed well. can be generated.

In step (1), it is preferable to add the organic solvent while stirring the aqueous dispersion using a stirring device equipped with a stirring blade such as a homodisper, mixer, or paddle blade. By bringing a stirring blade into contact with the aqueous dispersion and stirring it, particles having an outer shell containing CNF can be efficiently produced.

The stirring speed (rotation speed) when stirring the aqueous dispersion is preferably 500 rpm or more, more preferably 1000 rpm or more, from the viewpoint of suppressing agglomeration of CNF and reducing variations in shape and size of particles formed. More preferably, the speed is 1,500 rpm or more, even more preferably 2,000 rpm or more, and is preferably 5,000 rpm or less, more preferably 4,500 rpm or less, even more preferably 4,000 rpm or less, even more preferably 3,500 rpm or less, particularly preferably 3,000 rpm or less.

The stirring time is preferably 3 minutes or longer, more preferably 5 minutes or longer, and even more preferably 10 minutes or longer, from the viewpoint of uniformizing the shape and size of the particles having an outer shell containing CNF. In addition, the upper limit of the stirring time is preferably 180 minutes or less, more preferably 180 minutes or less, from the viewpoint of preventing the production time from becoming too long and preventing variations in the shape and size of the particles having an outer shell containing CNF. The time is 120 minutes or less, more preferably 60 minutes or less, even more preferably 40 minutes or less, particularly preferably 20 minutes or less. Note that the stirring time refers to the time from the addition of the organic solvent (C) to the end of stirring. In order to sufficiently disperse the organic solvent (C) and promote the formation of particles, stirring is continued even after the addition of the required amount of the organic solvent (C) is completed until the above-mentioned time has elapsed from the start of the addition of the organic solvent (C). It is desirable to continue.

In addition, the temperature of the aqueous dispersion is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C, from the viewpoint of suppressing agglomeration of CNF and reducing variations in shape and size of particles formed. In addition, from the viewpoint of suppressing volatilization of the added organic solvent, the temperature is preferably 45°C or lower, more preferably 40°C or lower, and still more preferably 35°C or lower.

Step (1) is preferably carried out at 80 kPa or higher, more preferably 90 kPa or higher, even more preferably 95 kPa or higher, and preferably 120 kPa or lower, more preferably 110 kPa or lower, even more preferably 105 kPa or lower, and particularly preferably at high pressure. Perform under atmospheric pressure. By preparing the composition under conditions close to atmospheric pressure, the composition can be prepared in a short time and the manufacturing equipment can be simplified. Moreover, step (1) may be performed in an atmosphere of air or inert gas. If it is in an air atmosphere, the manufacturing equipment can be simplified, and if it is in an inert gas atmosphere, it becomes easier to suppress deactivation of the composition. Note that when the sheet-like structure is applied to a product that releases the fluid mentioned above, the composition is prepared in an atmosphere of a specific type of gas so that this gas is encapsulated in the particles that are generated. It's okay.
These temperature conditions, pressure conditions, and atmospheric conditions also apply to step (2-1) and step (2-2) described later.

[Composition obtained in step (1) and constituent materials of the composition]
The composition prepared by step (1) is a mixture of CNF (A), water (B), and an organic solvent (C), and comprises particles having an outer shell containing CNF (A). Contains. Hereinafter, CNF (A), water (B), and organic solvent (C) may be collectively referred to as "components (A) to (C)."
In the above composition, at least a part of the organic solvent (C) is incorporated into the particles, specifically, encapsulated in the particles and forming an outer shell of the particles. It is preferable that at least one of the CNF(A) and the CNF(A) be adsorbed.
Here, "a state in which the organic solvent (C) is encapsulated in the particles" means that the particles form hollow particles from the outer shell containing CNF (A), and the organic solvent is contained in the hollow part of the hollow particles. (C) means the captured state. At this time, the organic solvent (C) is separated from the outside of the hollow particles by the outer shell that constitutes the hollow particles.
In the composition of one aspect of the present invention, the particles contain the organic solvent (C), and the CNF (A) forming the outer shell of the particles adsorbs the organic solvent (C). It may be in a state where In this specification, "the outer shell composed of CNF (A) adsorbs the organic solvent (C)" means that the organic solvent (C) is in the network structure of the outer shell composed of CNF (A). means to exist.

In the composition of one aspect of the present invention, an organic solvent (C) that is not incorporated into the particles may be present.

(Average particle diameter of particles with an outer shell containing CNF in the composition)
In order to make the average maximum Feret diameter of the closed space of the structure fall within the above-mentioned numerical range, it is necessary to set the average particle diameter of the particles having an outer shell containing CNF in the composition to an appropriate range. preferable.
The average particle diameter of the particles contained in the composition of one aspect of the present invention is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 7 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. It is also preferably 60 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, even more preferably 35 μm or less, particularly preferably 30 μm or less.
If the average particle diameter of the particles is 1 μm or more, it will be easier to suppress aggregation of the particles, and it will be easier to prevent the closed space of the structure from becoming too small.
Further, if the average particle diameter of the particles is 60 μm or less, floating of the particles can be easily suppressed.

Further, the standard deviation with respect to the average particle diameter of the particles contained in the composition of one embodiment of the present invention is such that the above-mentioned fluid is retained within the structure and, if necessary, the fluid is released to the outside by cleavage of the structure. In supply applications, from the viewpoint of stabilizing the amount of fluid released, the diameter is preferably 20 μm or less, more preferably 18 μm or less, even more preferably 15 μm or less, even more preferably 12 μm or less, and usually 1 μm or more.
In addition, in this specification, the average particle diameter of the particles and the standard deviation with respect to the average particle diameter are determined from an image obtained when the target composition is observed at a magnification of 500 to 1000 times using a digital microscope. It can be calculated.
That is, the average value of the particle diameters (outer diameters) of 36 arbitrarily selected particles among the particles shown in the image can be taken as the above-mentioned "average particle diameter." Furthermore, the "standard deviation with respect to the average particle diameter" can also be calculated from the particle diameter values of each of the 36 particles. The above standard deviation is the standard deviation of the population, and in the above calculation, the standard deviation is calculated for all 36 particle size values.

The viscosity of the composition used in one embodiment of the present invention at 23° C. and 50 rpm is preferably 500 mPa·s or more from the viewpoint of ease of removal from the container, ease of stirring, and ability to suppress sedimentation. , more preferably 1000 mPa·s or more, still more preferably 1200 mPa·s or more, and preferably 20000 mPa·s or less, more preferably 15000 mPa·s or less, still more preferably 12000 mPa·s or less.
In addition, in step (2-2) described below, in order to be able to apply the composition to the support well, the viscosity of the composition should be within the above numerical range at the temperature when applying the composition to the support. It is preferable to select the material so that

In addition, the TI value (viscosity at a rotation speed of 5 rpm/viscosity at a rotation speed of 50 rpm) at 23° C. of the composition used in one aspect of the present invention is determined by the storage stability, the ability to suppress sedimentation when stored in a container, and the TI value at 23° C. , from the viewpoint of ease of removal from the container, etc., is preferably 1.2 or more, more preferably 2 or more, even more preferably 3 or more, even more preferably 4 or more, and preferably 20 or less, more preferably It is 15 or less, more preferably 10 or less, even more preferably 8 or less.
Further, in this specification, the viscosity of the composition means a value measured using a B-type viscometer in accordance with JIS Z 8803:2011.

The pH of the composition used in one aspect of the present invention is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, preferably 10 or less, more preferably 9 or less, still more preferably 8 or less.

The composition used in one embodiment of the present invention may contain components other than the above components (A) to (C).
However, in the composition according to one embodiment of the present invention, the total content of CNF (A), water (B), and organic solvent (C) is preferably 60% based on the total amount (100% by mass) of the composition. The content is at least 65% by mass, more preferably at least 70% by mass, even more preferably at least 80% by mass, and preferably at most 100% by mass.

The active ingredient concentration of the composition used in one aspect of the present invention is preferably 0.5% by mass or more, more preferably 0.7% by mass or more, and even more preferably is 1.0% by mass or more, even more preferably 1.5% by mass or more, and preferably 50% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, even more preferably It is 10% by mass or less.
In addition, in this specification, the "active ingredient" refers to the components contained in the composition excluding water (B) and the organic solvent (C).

Particles having an outer shell containing CNF (A) and incorporating an organic solvent (C) are determined depending on the amount of CNF (A) to be blended, the ratio of the amount of CNF (A) to the organic solvent (C), and the organic solvent (C). It can be formed by appropriately adjusting the type of solvent (C).

In addition, in the composition used in one aspect of the present invention, as described below, the particles are mixed by blending an organic solvent (C) into an aqueous dispersion in which CNF (A) is dispersed in water (B). The composition is prepared to form a composition. In a more preferred embodiment, an organic solvent (C) which is a non-aqueous solvent is added to an aqueous dispersion in which CNF (A) is dispersed in water (B), so that the composition is formed so as to form the particles. Prepare. In a further preferred embodiment, an organic solvent (C) that makes the Hansen solubility parameter distance Ra 5.80 MPa ^1/2 or less is added to an aqueous dispersion in which CNF (A) is dispersed in water (B). , preparing a composition to form said particles.
In addition to the above, we also provide information on the shape of CNF (A) (diameter, fiber length, aspect ratio), the amount of water (B) and organic solvent (C), and the combination of water (B) and organic solvent (C). By appropriately setting the quantitative ratio, etc., the composition can be prepared so as to facilitate the formation of the particles.

(Cellulose nanofiber (CNF) (A))
Raw materials for CNF (A) used in one embodiment of the present invention include, for example, kraft pulp or sulfite pulp derived from wood; powdered cellulose obtained by pulverizing kraft pulp or sulfite pulp with a high-pressure homogenizer or mill; Microcrystalline cellulose powder purified by chemical treatment such as hydrolysis; Bast fiber pulp such as mulberry, gampi, and mitsumata; Cellulose-based raw materials derived from plants such as cotton pulp, kenaf, hemp, rice, bakasu, and bamboo; etc. Examples include raw materials. Since plant-derived CNF has a high degree of crystallinity, a linear structure, and a large aspect ratio, the strength of the outer shell can be increased, and it is also easily available.

Note that if a large amount of lignin remains in these raw materials, there is a risk of inhibiting the oxidation reaction of the raw materials, so cellulosic raw materials from which lignin has been removed from these raw materials are preferred.
In addition, it is also possible to use the above-mentioned cellulose-based raw material that has been pulverized using a dispersion device such as a high-speed rotation type, colloid mill type, high pressure type, roll mill type, or ultrasonic type, or a wet type high pressure or ultra-high pressure homogenizer.

Moreover, these cellulose-based raw materials may be chemically and/or physically modified to have enhanced functionality. Here, chemical modification includes addition of a functional group by acetylation, carboxylation, carboxysodiumization, esterification, cyanoethylation, acetalization, etherification, arylation, alkylation, acryloylation, isocyanation, etc. Another example is to compose or coat an inorganic substance such as a silicate or titanate by a chemical reaction or a sol-gel method.
In addition, physical modification of metals and ceramic raw materials includes physical vapor deposition methods (PVD methods) such as vacuum evaporation, ion plating, and sputtering, chemical vapor deposition methods (CVD methods), and plating methods such as electroless plating and electrolytic plating. For example, the surface may be coated with
It should be noted that these modification treatments may be performed at the time of fibrillation of the cellulosic raw material or before or after fibrillation.

The above-mentioned cellulose-based raw material can be made into CNF by defibrating it into nanofibers.
A specific method is to prepare a dispersion in which a cellulose-based raw material is dispersed in a dispersion medium such as water, and then apply a shear force to the cellulose-based raw material to obtain a dispersion containing CNF. It will be done.
The method of applying shear force to cellulose raw materials is to add the cellulose raw materials to a dispersion medium such as water, and then use a high-speed rotation type, colloid mill type, high pressure type, roll mill type, ultrasonic type, etc. A method of preparing is preferred.
At this time, the pressure applied to the dispersion is preferably 50 MPa or more, more preferably 100 MPa or more, and still more preferably 140 MPa or more.
From the viewpoint of applying a strong shearing force to the cellulosic raw material under such high pressure, it is preferable to use a wet high pressure or ultrahigh pressure homogenizer.

The average diameter (thickness) of the CNF used in one embodiment of the present invention is preferably 1.0 nm or more, more preferably 1.0 nm or more, from the viewpoint of facilitating the formation of the particles and improving the film strength of the formed particles. 1.5 nm or more, more preferably 2.0 nm or more, even more preferably 2.5 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 200 nm or less, even more preferably 100 nm or less. be.

The average fiber length of the CNF used in one aspect of the present invention is preferably 0.01 μm or more, more preferably 0.1 μm, from the viewpoint of facilitating the formation of the particles and improving the film strength of the formed particles. Above, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, preferably 10 μm or less, more preferably 7.0 μm or less, still more preferably 5.0 μm or less, even more preferably 2.5 μm or less. It is.

The average aspect ratio of CNF (A) used in one aspect of the present invention is preferably 5 or more, more preferably 10 or more, from the viewpoint of facilitating the formation of the particles and improving the film strength of the formed particles. More preferably, it is 15 or more, more preferably 10,000 or less, more preferably 5,000 or less, still more preferably 3,000 or less, even more preferably 1,000 or less, particularly preferably 500 or less.

Note that the "aspect ratio" is the ratio of the length to the thickness of the target CNF [length/thickness], and the "length" of the CNF is the ratio between the two most distant points of the CNF. refers to distance.
In addition, if a part of the target CNF is in contact with other CNFs and it is difficult to determine the "length", measure the length of only the part of the target CNF where the thickness can be measured. , the aspect ratio of the portion may be within the above range.
The diameter (thickness) and fiber length of CNF (A) can be measured using a transmission electron microscope. In addition, the average diameter (thickness) and average fiber length of CNF (A) can be determined by measuring the diameter (thickness) and fiber length of a plurality of arbitrarily selected CNFs and calculating the average value of each. can get. The average aspect ratio of CNF (A) can be calculated using the average diameter (thickness) and average fiber length obtained in this way. The diameter (thickness), fiber length, average value thereof, and average aspect ratio of CNF (A) can be specifically calculated by the method shown in Examples.

In addition, in the manufacturing method of this embodiment, since excessive stress is not applied to the CNF when preparing the composition, the fiber diameter and fiber length of the CNF before blending remain almost the same even in the sheet-like structure. maintained. Therefore, the numerical ranges for the fiber diameter, fiber length, and aspect ratio of CNF mentioned above are for CNF before preparing the composition, CNF after preparing the composition, and the structure fabricated using the composition described below. The same applies to any of the CNFs.

(Content of CNF in composition)
In the composition used in one embodiment of the present invention, the amount of CNF (A) is determined based on the total amount (100% by mass) of the composition to facilitate the formation of the particles and to increase the film strength of the formed particles. From the viewpoint of improving From the viewpoint of appropriately adjusting the viscosity of the composition so as to facilitate the formation of the particles, preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less, even more preferably 5% by mass or less. The amount is not more than 3% by mass, particularly preferably not more than 3% by mass.

(Water (B))
In the composition used in one aspect of the present invention, most of the water (B) is adsorbed on the outer shell of the particles or is present on the outside of the particles.
However, a part of the water (B) may be encapsulated together with the organic solvent (C) inside the particles.

In the composition used in one embodiment of the present invention, from the viewpoint of preparing the composition to have an appropriate viscosity and facilitating the formation of the particles, the amount of water (B) to be blended is determined based on the total amount of the composition (100 mass %), preferably 15% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, even more preferably 60% by mass or more, and preferably 99% by mass or less, more preferably Preferably it is 98.7% by mass or less, more preferably 98.5% by mass or less.

In the composition used in one embodiment of the present invention, from the viewpoint of preparing the composition to have an appropriate viscosity and facilitating the formation of the particles, the blending ratio of water (B) to 100 parts by mass of CNF (A) is , preferably 500 parts by mass or more, more preferably 1000 parts by mass or more, still more preferably 2000 parts by mass or more, even more preferably 3000 parts by mass or more, and preferably 20000 parts by mass or less, more preferably 15000 parts by mass. The amount is preferably 10,000 parts by mass or less.

(Aqueous dispersion)
As mentioned above, an aqueous dispersion containing CNF and water can be obtained by dispersing a cellulosic raw material in water and then applying a shear force to the cellulosic raw material, and then using the dispersion as it is as an aqueous dispersion. can. A commercially available aqueous dispersion of CNF can also be used.
The pH of the aqueous dispersion is preferably 4 or more, more preferably 5 or more, from the viewpoint of suppressing agglomeration of CNF (A) in the aqueous dispersion and reducing variations in shape and size of particles formed. It is preferably 6 or more, more preferably 10 or less, more preferably 9 or less, even more preferably 8 or less.

(Organic solvent (C))
Organic solvents (C) are non-aqueous, from the viewpoint that they form an independent phase when mixed with water and can temporarily take an emulsified state when added to water and stirred. It is preferable to use a system solvent. By using a non-aqueous solvent, particles having an outer shell containing CNF can be produced without using a dispersant such as a surfactant.

（前記式中、δＤは、前記有機溶剤のハンセン溶解度パラメータの分散成分、
δＰは、前記有機溶剤のハンセン溶解度パラメータの極性成分、
δＨは、前記有機溶剤のハンセン溶解度パラメータの水素結合成分を示す。）The organic solvent (C) more preferably has a Hansen solubility parameter distance Ra of 5.80 MPa ^1/2 or less at 25° C., which is expressed by the following formula (1).

(In the above formula, δD is a dispersion component of the Hansen solubility parameter of the organic solvent,
δP is the polar component of the Hansen solubility parameter of the organic solvent,
δH represents the hydrogen bond component of the Hansen solubility parameter of the organic solvent. )

The Hansen solubility parameter is a solubility parameter introduced by Hildebrand, which Hansen divided into three components: δD (dispersion component), δP (polar component), and δH (hydrogen bond component). This is shown in dimensional space.
Note that the values of δD, δP, and δH are unique values for each organic solvent, and are values calculated from specific calculations.
More specifically, the definition and calculation method of the Hansen solubility parameter is as described in "Hansen Solubility Parameters: A Users Handbook (written by Charles M. Hansen, CRC Press, 2007)".
In addition, in this specification, the values of δD, δP, and δH are obtained from the database included in the calculation software "Hansen Solubility Parameters in Practice (HSPiP) Version 4.1.03" (written by Steven Abbott, Charles M. Hansen, and Hiroshi Yamamoto). The value of was used.

The present inventors have noticed that the ease with which the particles are formed differs depending on the type of organic solvent (C) to be blended.
When the Hansen solubility parameters of each organic solvent were plotted in a three-dimensional space, it was found that in the three-dimensional space, the organic solvent used to form the particles was densely distributed in a certain area. I understand.
Therefore, when we drew the largest sphere (interaction sphere) in which all the plots of the organic solvents in which the particles were formed were included inside, and the plots of the organic solvents in which the particles were not formed were on the outside, we found that The radius of the sphere was "5.80 MPa ^1/2 ".
The distance Ra calculated from equation (1) means the distance between the plot of the target organic solvent and the center of the sphere in the three-dimensional space of the Hansen solubility parameter. In other words, if the distance Ra is less than or equal to "5.80 MPa ^1/2 " which is the radius of the sphere, the plot of the target organic solvent is located inside the sphere and is likely to form the particles. It can be determined that it is a solvent.

The values of δD, δP, and δH of typical organic solvents used in the Examples and Comparative Examples described below, and the distance Ra calculated from the above formula (1) (all units are "MPa ^1/2 ") ) are shown in Table 1.

As shown in Table 1, the organic solvents (C) with a distance Ra of 5.80 MPa ^1/2 or less are heptane, n-hexadecane, methyl ethyl ketone, and n-dodecane. As shown in Examples below, it was found that the particles were easily formed when these organic solvents were used.
In view of this result, even if the organic solvent is not shown in Table 1, it is presumed that the particles can be easily formed if the organic solvent (C) has a distance Ra of 5.80 MPa ^1/2 or less.
Note that the values of δD, δP, and δH of organic solvents other than those shown in Table 1 can be calculated from the molecular structure of the organic solvent, or the values of δD, δP, and δH as shown in Table 1 can be calculated from the molecular structure of the organic solvent. The value of δH can also be calculated by conducting experiments on solubility with organic solvents for which the value is known from various literatures.

The organic solvent (C) may be used alone or as a mixed solvent in which two or more types are used together.
When the organic solvent (C) is a mixed solvent, the values of the three components (δD, δP, δH) of the weighted average Hansen solubility parameter are determined from the mixing ratio (volume ratio) of the mixed solvent, and calculated from the above formula (1). It is preferable that the distance Ra is 5.80 MPa ^1/2 or less.
Therefore, even if an organic solvent has a distance Ra of more than 5.80 MPa ^1/2 when used alone, it can be mixed with another organic solvent with a distance Ra of 5.80 MPa ^1/2 or less at an appropriate volume ratio to increase the distance Ra. It is also possible to use the organic solvent (C) that facilitates the formation of the particles by using a mixed solvent prepared such that the pressure is 5.80 MPa ^1/2 or less.
In other words, if you want to obtain a composition containing particles incorporating an organic solvent that has a distance Ra of more than 5.80 MPa ^1/2 when used alone, it is thought that it will be easier to prepare by using a mixed solvent as described above. .

It should be noted that by using an organic solvent (C) in which the distance Ra is 5.80 MPa ^1/2 or less, it is thought that the particles are easier to form than when using other organic solvents, but the particles may not be formed. Whether or not this is possible also changes depending on the blending amounts of CNF (A), water (B), and organic solvent (C), the shape of CNF (A), and the selection of modifying groups.
Therefore, by using an organic solvent (C) with which the distance Ra is 5.80 MPa ^1/2 or less and taking into consideration the matters described in each component section of this specification, the particles can be formed more easily. It is preferable to prepare the

The organic solvent (C) used in one embodiment of the present invention preferably includes an organic solvent (C1) having less than 20 carbon atoms.
The organic solvent (C1) having less than 20 carbon atoms is easily incorporated into the CNF (A) and the particles are easily formed.
In other words, organic solvents with a large number of carbon atoms tend to aggregate molecules of the organic solvent and have high viscosity, making it difficult to form particles that are close to perfect spheres. As a result, it is thought that a large proportion of such organic solvents remain outside the particles without being incorporated into the cellulose nanofibers (A).

From the above viewpoint, the blending ratio of the organic solvent (C1) in the organic solvent (C) is preferably 20% by mass or more, more preferably 35% by mass or more, based on the total amount (100% by mass) of the organic solvent (C). , more preferably 50% by mass or more, even more preferably 70% by mass or more.

In the composition used in one aspect of the present invention, from the viewpoint of facilitating the formation of the particles, the blending amount of the organic solvent (C) is preferably 0.05% based on the total amount (100% by mass) of the composition. % by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and preferably 80% by mass or less, more preferably 60% by mass or more. It is at most 45% by mass, more preferably at most 42% by mass, even more preferably at most 40% by mass, particularly preferably at most 38% by mass.

(Content of organic solvent in the composition)
In the composition used in one aspect of the present invention, from the viewpoint of facilitating the formation of the particles, the blending ratio of the organic solvent (C) to 100 parts by mass of CNF (A) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 50 parts by mass or more, still more preferably 75 parts by mass or more, still more preferably 90 parts by mass or more, and preferably 6000 parts by mass or less, more preferably The amount is preferably 4,500 parts by mass or less, more preferably 4,000 parts by mass or less, even more preferably 3,500 parts by mass or less.

(ratio of water and organic solvent)
In the composition used in one embodiment of the present invention, from the viewpoint of facilitating the formation of the particles, the blending ratio [(B)/(C)] of water (B) and organic solvent (C) is determined by mass ratio. , preferably 0.1 or more, more preferably 0.5 or more, even more preferably 1.0 or more, even more preferably 1.5 or more, and preferably 1000 or less, more preferably 700 or less, even more preferably is 500 or less, more preferably 300 or less, particularly preferably 100 or less.

(other ingredients)
The composition used in one embodiment of the present invention may contain components other than components (A) to (C) to the extent that the effects of the present invention are not impaired.
Such other components are appropriately selected depending on the use of the composition, and include, for example, colorants, antioxidants, pH adjusters, sweeteners, and the like.

The composition used in one embodiment of the present invention may contain a surfactant.
However, when compositions containing surfactants are used for human contact applications, the surfactants also act as penetrants and irritating irritants, especially for users with sensitive skin. Furthermore, there is a concern that compositions containing surfactants may affect the stability of the physical properties of the composition. Furthermore, when the holder is applied to the above-mentioned fluid retention product or fluid release product, there is a risk that the surfactant may be mixed into the fluid released by cleavage of the structure or the fluid released through the membrane. There is a possibility that the surfactant affects the stability of the physical properties of the structure, leading to loss of fluid retention.
Therefore, in the composition of one aspect of the present invention, the content of the surfactant is preferably as small as possible.
From the above viewpoint, in the composition used in one aspect of the present invention, the content of the surfactant is preferably less than 10 parts by mass, more preferably less than 1 part by mass, based on 100 parts by mass of the total amount of CNF(A). , more preferably less than 0.1 parts by weight, even more preferably less than 0.01 parts by weight, particularly preferably less than 0.001 parts by weight, and most preferably 0 parts by weight. By adjusting the surfactant content in the composition in this way, the surfactant content in the structure can be within the above range.

In addition, the composition used in one aspect of the present invention may contain a polysaccharide other than CNF(A), but it improves the thermal stability of the particles and makes it easier to form the particles. From this point of view, the content of the polysaccharide is preferably as low as possible.
From the above viewpoint, in the composition used in one aspect of the present invention, the content of polysaccharides other than CNF(A) is preferably less than 10 parts by mass, more preferably less than 100 parts by mass of the total amount of CNF(A). is less than 1 part by weight, more preferably less than 0.1 part by weight, even more preferably less than 0.01 part by weight, particularly preferably 0 part by weight. By adjusting the content of polysaccharides other than CNF(A) in the composition in this way, the content of polysaccharides other than CNF(A) in the structure can be within the above-mentioned range.

[Step (2)]
In step (2), the composition is applied onto a support to form a coating film, and the coating film is dried to form a sheet-like structure. In step (2), from the viewpoint of avoiding excessive stress being applied to the particles having an outer shell containing CNF in the composition prepared in step (1), it is preferable to first apply the composition on a support. (Step (2-1)), and then the composition on the support is uniformly spread and applied (Step (2-2)).
(Step (2-1): Step of supplying the composition to one side of the support)
In step (2-1), for example, the composition containing particles with an outer shell containing CNF is prepared by tilting the container containing the composition and gradually moving the composition from the container to the support by its own weight. is supplied onto the support. Alternatively, the above composition may be supplied onto the support using a pump or the like.
The temperature conditions, pressure conditions, and atmospheric conditions in step (2-1) may be set in the same manner as described in step (1).

(Step (2-2): Step of applying the composition to the support (Step (2-2)))
In step (2-2), the composition supplied onto the support in step (2-1) is applied onto the support using a coating device. In one embodiment, the applicator is moved relative to the support along the plane of the support to apply the composition to the support (step (2-2)).
Here, the coating gap when forming the coating film is to form a sufficient number of closed spaces composed of a film containing CNF in a good shape, and to avoid the need for drying that takes time or heating at a relatively high temperature. From the viewpoint of preventing some of the particles in the composition after application from breaking or disappearing as a result of the need for It is even more preferably 200 μm or more, more preferably 1250 μm or less, more preferably 1000 μm or less, even more preferably 750 μm or less, even more preferably 500 μm or less.

Examples of methods for applying the composition include spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, gravure coating, and air knife coating. , dip coating method, etc. Among these, knife coating method and gravure coating method are preferred.
In step (2-2), a jig capable of forming a gap larger than the diameter of the particles is used in order to avoid particles having an outer shell containing CNF in the composition from being broken by coating. is preferred. In this case, the gap formed by the jig is preferably 1.5 times or more, more preferably 5 times or more, still more preferably 7.5 times or more, even more preferably, the diameter of the particle having the outer shell containing CNF. is 9 times or more, preferably 62.5 times or less, more preferably 50 times or less, even more preferably 37.5 times or less, and even more preferably 25 times or less.

In step (2-2), from the viewpoint of preventing volatilization of the organic solvent, the temperature of the composition is preferably 45°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower. I do. In addition, from the viewpoint of preventing the viscosity of the composition from becoming too high and making it impossible to form a uniform coating layer or damaging the particles having an outer shell containing CNF, it is preferably 5° C. or higher, more preferably 10° C. The coating is carried out in an environment where the temperature is 15° C. or higher, more preferably 15° C. or higher.
The pressure conditions and atmospheric conditions in step (2-2) may be set in the same manner as described in step (1).

Note that it is also possible to supply the composition to the support and apply it at the same time (that is, perform step (2-1) and step (2-2) at the same time) using a coating device such as a die coater. However, in this case, it is preferable to adjust the injection conditions and the like so that excessive stress is not applied to the particles in the composition having an outer shell containing CNF.

(Step (2-3): Drying the composition applied on the support)
In step (2-3), the layer of the composition coated on the support is dried by heating or the like to form a layer including a plurality of closed spaces made of a CNF-containing film. Specifically, a layer of the composition coated on the support is dried using a heater or the like, and water and organic solvents, including those incorporated inside the particles, are evaporated from the composition. A layer including a plurality of closed spaces made of a film containing CNF is formed.
The mechanism by which the closed space composed of the CNF-containing membrane is formed in step (2-3) is presumed to be as follows, although it is not necessarily limited to this. In other words, in the process of volatilization of water and organic solvent from the layer of the composition, some of the particles stick to each other, some of the particles move to more stable positions, and the The gap gradually disappears, and on the other hand, the CNF gathered at the interface between the organic solvent and water remains stable, so the film containing CNF is not destroyed, and a dense closed space is finally formed. It is assumed that.

In step (2-3), the temperature is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, and still more preferably 130°C or lower. Dry at temperatures below ℃. By drying at 90° C. or higher, water and organic solvent are quickly removed, making it easier to form a closed space with a good shape. By drying at 150° C. or lower, it becomes easier to prevent the shape and size of the closed space from becoming non-uniform and from deforming the support.
The pressure conditions and atmospheric conditions in step (2-3) may be set in the same manner as described in step (1).

In step (2-3), the time is preferably 10 seconds or more, more preferably 30 seconds or more, and even more preferably, from the viewpoint of preventing the water and organic solvent from remaining without being removed and causing the shape of the closed space to collapse. The drying time is preferably 1 minute or more, even more preferably 5 minutes or more, even more preferably 10 minutes or more, and preferably 2 hours or less, more preferably 1 hour or less, and even more preferably 30 minutes or less.

The present invention will be specifically explained with reference to the following examples, but the present invention is not limited to the following examples. In addition, the physical property values in the following production examples and examples are values measured by the following method.

<Average diameter (thickness), average length, and average aspect ratio of CNF>
Using a transmission electron microscope (manufactured by Carl Zeiss, product name "LEO912"), the diameter (thickness) and length of 10 arbitrarily selected CNFs were measured, and the average value of the 10 CNFs was calculated from the target. The "average diameter (thickness)" and "average length" of the CNF. Further, "average length/average diameter (thickness)" was defined as the average aspect ratio.
<pH of aqueous dispersion and composition>
Two-point calibration of pH 4.01 standard solution and pH 6.86 standard solution using a compact pH meter (manufactured by Horiba Advanced Techno Co., Ltd., product name "LAQUAtwin pH-22B") in an environment of 23°C and 50% relative humidity. After performing this, a sample was dropped to cover the entire flat sensor and measurements were taken.

(Example 1)
1. Preparation of Composition 1 In preparing Composition 1, the following commercially available aqueous dispersion (1) containing CNF was used.
-Aqueous dispersion (1) Product name: "BiNFi-s AMa10002", manufactured by Sugino Machine Co., Ltd. An aqueous dispersion containing 2% by mass of mechanically processed CNF having an average diameter (thickness) of 76.8 nm, an average length of 1.4 μm, and an average aspect ratio of 18.2.
The aqueous dispersion (1) contained 4900 parts by mass of water based on 100 parts by mass of CNF, and the pH of the aqueous dispersion (1) was 7.0.
5000.0 parts by mass of the aqueous dispersion (1) (100.0 parts by mass of CNF) was put into a container, and an ultra-high-speed multi-stirring system (manufactured by Primix, product name "Labolution (registered trademark)", stirring blades: The 23° C. aqueous dispersion was stirred at a rotational speed of 3000 rpm using a Homodisper (manufactured by the same company, blade diameter 35 mm). After the stirring was started, n-dodecane was added at a rate of 5 parts by mass every 10 seconds to 100 parts by mass of the total amount of the aqueous dispersion. Continue adding n-dodecane to 5000.0 parts by mass of the above aqueous dispersion (100.0 parts by mass of CNF) until n-dodecane reaches 100 parts by mass, and stop stirring after 10 minutes from the start of stirring, Composition 1 was prepared comprising particles with an outer shell comprising CNF.

2. Preparation of sheet-like structure 1 Composition 1 was gently placed on the easily adhesive layer surface of a 50 μm thick polyethylene terephthalate film (Cosmoshine (registered trademark) manufactured by Toyobo Co., Ltd., product number “A4100”, thickness: 50 μm). Composition 1 was then applied to the film using an applicator (coating gap: 254 μm (10 mil)). Furthermore, sheet-like structure 1 was produced by heating and drying at 120° C. for 10 minutes.
All steps from preparation to application of Composition 1 were performed in an air atmosphere, under atmospheric pressure, and at 23°C. Thereafter, the sheet-like structure 1 was produced by heating and drying at 120° C. for 10 minutes.

(Examples 2 to 5)
A composition containing particles with an outer shell containing CNF was prepared using the same procedure as in Example 1, except that the total amount of n-dodecane added was changed to 500 parts by mass, 1000 parts by mass, 2000 parts by mass, and 3000 parts by mass, respectively. Items 2 to 5 were prepared. Then, sheet-like structures 2 to 5 were produced in the same manner as in Example 1 except that compositions 2 to 5 were used in place of composition 1, respectively.

(Example 6)
Composition 1 was applied to the easily adhesive layer surface of the polyethylene terephthalate film in the same manner as in Example 5 except that the coating gap of the applicator was changed to 762 μm (30 mil). Furthermore, a sheet-like structure 6 was produced in the same manner as in Example 5 except that the drying time was changed to 20 minutes.

(Examples 7 to 9)
An outer shell containing CNF was prepared in the same manner as in Example 1, except that 100 parts by mass of methyl ethyl ketone (MEK), 100 parts by mass of heptane, and 100 parts by mass of n-hexadecane were used in place of 100 parts by mass of n-dodecane. Compositions 7-9 were prepared containing particles comprising: Then, sheet-like structures 7 to 9 were produced in the same manner as in Example 1, except that Compositions 7 to 9 were used in place of Composition 1, respectively.

(Example 10)
Composition 10 containing particles with an outer shell containing CNF was prepared in the same manner as in Example 1, except that the total amount of n-dodecane added was changed to 10 parts by mass. Then, a sheet-like structure 10 was produced in the same manner as in Example 1, except that Composition 10 was used instead of Composition 1.

(Example 11)
1. Preparation of Composition 11 In preparing Composition 11, the following commercially available aqueous dispersion (2) containing CNF was used.
-Aqueous dispersion (2): Product name "TEMPO oxidized CNF", manufactured by Nippon Paper Industries Co., Ltd. An aqueous dispersion containing 1% by mass of chemically treated cellulose nanofibers having an average diameter (thickness) of 3.8 nm, an average length of 0.7 μm, and an average aspect ratio of 184.
The aqueous dispersion (2) contained 9900 parts by mass of water based on 100 parts by mass of cellulose nanofibers, and the pH of the aqueous dispersion (2) was 7.0.
5000.0 parts by mass of aqueous dispersion (2) (100.0 parts by mass of CNF) was put into a container, and an ultra-high-speed multi-stirring system (manufactured by Primix, product name "Labolution (registered trademark)", stirring blades: The 23° C. aqueous dispersion was stirred at a rotational speed of 3000 rpm using a Homodisper (manufactured by the same company, blade diameter 35 mm). After the stirring was started, n-dodecane was added at a rate of 5 parts by mass every 10 seconds. Continue adding n-dodecane to 5000.0 parts by mass of the above aqueous dispersion (100.0 parts by mass of CNF) until n-dodecane reaches 100 parts by mass, and stop stirring after 10 minutes from the start of stirring, Composition 11 was prepared comprising particles with an outer shell comprising CNF.

2. Preparation of sheet-like structure 11 Composition 11 was gently placed on the easily adhesive layer surface of a 50 μm thick polyethylene terephthalate film (Cosmoshine (registered trademark) manufactured by Toyobo Co., Ltd., product number “A4100”, thickness: 50 μm). Then, Composition 10 was applied to the film using an applicator (coating gap: 254 μm (10 mil)), and the film was further dried by heating at 120° C. for 10 minutes, thereby producing sheet-like structure 11.
All steps from preparation to application of Composition 11 were performed in an air atmosphere at atmospheric pressure and at 23°C. Thereafter, the sheet-like structure 11 was produced by heating and drying at 120° C. for 10 minutes.

(Example 12)
Composition 12 containing particles with an outer shell containing CNF was prepared in the same manner as in Example 11, except that the total amount of n-dodecane added was changed to 3000 parts by mass. Then, a sheet-like structure 12 was produced in the same manner as in Example 11 except that Composition 12 was used instead of Composition 11.

(Example 13)
Composition 13 containing particles with an outer shell containing CNF was prepared in the same manner as in Example 11, except that 200 parts by mass of n-hexadecane was used instead of 100 parts by mass of n-dodecane. Then, a sheet-like structure 13 was produced in the same manner as in Example 11, except that Composition 13 was used instead of Composition 11.

(Comparative example 1)
Composition C1 was prepared in the same manner as in Example 1 except that 100 parts by mass of n-dodecane was not added. The stirring time was 10 minutes as in Example 1. Then, a sheet-like structure C1 was produced in the same manner as in Example 1 except that Composition C1 was used instead of Composition 1.

(Comparative Examples 2 to 5)
Composition was performed in the same manner as in Example 1, except that 100 parts by mass of hexane, 100 parts by mass of dimethyl sulfoxide (DMSO), 100 parts by mass of aniline, and 100 parts by mass of ethanol were used in place of 100 parts by mass of n-dodecane. Products C2 to C5 were prepared. Then, sheet-like structures C2 to C5 were produced in the same manner as in Example 1, except that Compositions C2 to C5 were used in place of Composition 1, respectively.
Table 2 summarizes the components of the compositions prepared in Examples and Comparative Examples.

Compositions 1 to 13, C1 to C5, and sheet structures 1 to 13, C1 to C5 were measured and evaluated using the following procedure. The results are shown in Table 3.

<Presence or absence of closed space>
Each sheet-like structure was cut in the thickness direction. Then, each cut surface was observed by SEM to confirm whether or not a hollow closed space was formed. FIG. 3 shows an example of a SEM image of a cross section of the sheet-like structure 6 in the thickness direction.

<Average thickness of film containing CNF>
The above-mentioned cut surface of each sheet-like structure was observed using a scanning electron microscope (SEM) (model S-4700 manufactured by Hitachi, Ltd.), and 36 closed spaces were arbitrarily selected from the obtained enlarged image. One arbitrary side constituting each was identified, and the thickness at approximately the center of that side was measured. By calculating their average value, it was determined as the average thickness of the CNF-containing membrane in the plurality of closed spaces.

<Maximum Feret diameter of the enclosed space of the structure and its average>
By observing the cut surface of each sheet-like structure with a SEM, arbitrarily selecting 36 closed spaces from the obtained SEM images, measuring the maximum Feret diameter of each, and calculating their average value, It was taken as the average of the maximum Feret diameter.
<b/a>
The above-mentioned cut surface of each sheet-like structure was observed by SEM, 36 closed spaces were arbitrarily selected from the obtained SEM image, and for each, the maximum length a in the thickness direction of the structure and the The maximum length b in the plane direction was measured to determine the value of b/a, and the average value thereof was calculated to obtain the value of b/a.

<Structure thickness and bulk density>
The mass and thickness of the sheet-like structure with a support were measured according to the following procedure. Then, using these, the bulk density of the sheet-like structure without a support was calculated.
Mass: After cutting the sheet-like structure with a support into a size of 100 mm x 100 mm, measure the mass and subtract the known mass of the support to calculate the mass of the sheet-like structure without the support. Calculated.
Thickness: Using a constant pressure film thickness meter, measure the thickness of the entire sheet-like structure including the support, and then subtract the known thickness of the base to calculate the thickness of the sheet-like structure without the support. (corresponding to the symbol L in FIG. 1(A)) was calculated.

<Pressure resistance>
A cylindrical metal weight with a radius of 1.5 cm and a mass of 145 g (equivalent to 1 MPa) was placed on the surface of each sheet-like structure, and after standing for 1 minute, the shape of the weight was transferred to each sheet-like structure. The pressure resistance was evaluated by checking whether the If the shape of the weight was not transferred to the surface of the sheet-like structure even after performing the above procedure, it was determined that the pressure resistance was good, and the evaluation was given as "A". When the shape of the weight was transferred to the surface of the sheet-like structure by the above procedure, it was judged that the pressure resistance was inferior, and the evaluation was given as "F".

As is clear from Table 3, in Examples 1 to 13, particles with an outer shell containing CNF could be produced in the composition without using a dispersant such as a surfactant. Further, in Examples 1 to 13, by applying the composition to a support and drying it, a sheet-like structure having a self-retaining property and having a large number of closed spaces composed of a CNF-containing film was obtained. was completed. FIG. 3 is a SEM image of a cross section in the thickness direction of the sheet-like structure 1 produced in Example 6. It was confirmed that all of the sheet-like structures 1 to 13 have a structure in which a pair of adjacent closed spaces share a membrane containing CNF, similar to the closed spaces shown in the SEM image of FIG. 3. did. In the sheet-like structures of Examples 1 to 13, the average maximum Feret diameter of the closed spaces was in the range of 1 to 60 μm, and small-diameter closed spaces could be formed. In addition, sheet-like structures 1 to 13 have high pressure resistance, with no transfer of the shape of the weight observed in the pressure resistance evaluation, and are strong enough to not collapse even when rolled into a roll. It turned out that I was doing it.

As is clear from Examples 1 to 5 and 9, by adjusting the amount of organic solvent used, the average maximum Feret diameter of the closed space, the thickness of the film containing CNF, the thickness of the structure, b/a It can be seen that the value of and the bulk density of the structure can be varied. Furthermore, it can be seen that as the thickness of the CNF-containing film in the sheet-like structure becomes smaller, the sheet-like structure becomes thicker and the bulk density of the sheet-like structure becomes smaller. When the size of the particles with a CNF-containing shell included in the composition is relatively small, the influence of the thickness of the capsule shell per volume of the internal space of the capsule is greater than that for large diameter capsules. Therefore, as the thickness of the capsule shell varies, the size of the space inside the particle also changes, and the average maximum Feret diameter of the closed space in the final structure and the diameter of the CNF-containing film vary. It is presumed that this affects the thickness and the b/a value. This suggests that since the capsule has a relatively small diameter, it is possible to control the porosity of the structure to some extent by adjusting the thickness of the outer shell of the capsule.
Further, as is clear from Example 1 and Examples 7 to 9, the size of the particles with a CNF-containing shell contained in the composition can be changed by changing the type of organic solvent. I understand.

Furthermore, as is clear from Examples 5 and 6, by changing the thickness of the applied composition by changing the gap of the applicator when applying the composition, the average maximum Feret diameter of the closed space and It can be seen that the thickness of the structure can be changed significantly without changing the thickness of the film containing CNF.
Furthermore, as is clear from Examples 11 to 13, even when the type of CNF is changed, the same tendency as described above is shown (that is, by changing the type and amount of organic solvent added, the occlusion The average maximum Feret diameter of the space, the thickness of the film containing CNF, the thickness of the structure, the value of b/a, and the bulk density of the structure can be varied).
On the other hand, in Comparative Examples 1 to 5, particles with an outer shell containing CNF could not be produced in the composition, and as a result, a closed space formed of a film containing CNF was generated in the structure. I couldn't do it.

The sheet-like structure obtained by the manufacturing method of the present invention can be a structure that includes a plurality of closed spaces made of a membrane containing CNF, and in which the sizes of the plurality of closed spaces are small. Therefore, for example, a structure that retains fluid inside a closed space and, when necessary, applies pressure to rupture a part of the structure and supply the fluid to the outside, or a structure that retains fluid inside a closed space. It can be used as a sustained release structure that can gradually release fluid. Further, it can be used as a heat insulating material, an absorbent material, a sound absorbing material, an insulating material, a base material for a flexible printed wiring board, a packaging material, etc. Furthermore, when the structure is strongly pressed with a finger, the closed space is compressed and destroyed, leaving pressure marks including fingerprints on the surface of the structure, so it can also be used as a trace recording material.

30: Composition 31: Layer having multiple closed spaces (sheet-like structure)
32: Particles 33, 33a, 33b with an outer shell containing CNF: Closed space 34: Medium mainly composed of water 35: Membrane 35a containing CNF: Membrane 40 shared by a pair of adjacent closed spaces: Support 40a: Application surface 50: Sheet-like structure with support a: Maximum length in the thickness direction of the structure in the closed space b: Maximum length in the planar direction of the structure in the closed space df: Maximum Ferret of the closed space Diameter dm: Thickness of membrane containing CNF L: Thickness of layer having multiple closed spaces

Claims (11)

A structure comprising a membrane containing cellulose nanofibers and a plurality of closed spaces formed from the membrane, wherein the average maximum Feret diameter of the plurality of closed spaces in a cross section of the structure is 1 μm to 60 μm. The structure has a sheet shape, and in the cross section of the structure in the thickness direction, the maximum length of the closed space in the thickness direction of the structure is a, and the plane of the structure of the closed space is A structure in which the average b/a of the plurality of closed spaces is greater than 1.5 and less than or equal to 10 , where b is the maximum length in the direction. The structure according to claim 1, wherein a pair of adjacent closed spaces among the plurality of closed spaces share at least one of the membranes. The structure according to claim 1 or 2, wherein the average thickness of the film containing cellulose nanofibers is 10 nm to 2000 nm. The structure according to any one of claims 1 to 3, wherein the structure has a bulk density of 0.001 to 1.4 g/cm ³ . The structure according to any one of claims 1 to 4, wherein the structure has a thickness of 0.5 to 300 μm. The structure according to any one of claims 1 to 5, wherein an average b/a of the plurality of closed spaces is larger than 2 in a cross section in the thickness direction of the structure. The structure according to any one of claims 1 to 6, wherein the cellulose nanofiber is a plant-derived cellulose nanofiber. The structure according to any one of claims 1 to 7, wherein the content of polysaccharides other than the cellulose nanofibers is less than 10 parts by mass based on 100 parts by mass of the cellulose nanofibers. The structure according to any one of claims 1 to 8, wherein the cellulose nanofibers have an average diameter (thickness) of 1 to 1000 nm. The structure according to any one of claims 1 to 9, wherein the cellulose nanofibers have an average fiber length of 0.01 to 10 μm. A structure with a support, wherein the structure according to any one of claims 1 to 10 is provided on a support.

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