Method for producing cellulose nanofiber composition

Abstract

To provide a method for producing a cellulose nanofiber composition that allows cellulose nanofiber to be well dispersed, and is capable of easily widening a range of application of cellulose.SOLUTION: A method for producing a cellulose nanofiber composition includes: a dispersion medium preparation process for preparing a dispersion medium; a cellulose derivative addition process for adding a cellulose derivative to the prepared dispersion medium to prepare a cellulose derivative-containing solution; and a cellulose nanofiber addition process for adding cellulose nanofiber to the cellulose derivative-containing solution.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a nanocellulose composition, and more particularly, to a method for producing a cellulose nanofiber composition that exhibits affinity even for hydrophobic substances.

Background Art

[0002] Nanocellulose is a cellulose fiber on the order of nanometers in thickness obtained by defibrating plant fibers such as pulp in an aqueous medium. Nanocellulose is classified into cellulose nanofibers, cellulose crystals, cellulose whiskers, bacterial cellulose, etc. by the structured cellulose of nanocellulose. Since cellulose nanofibers are lightweight and have high strength, for example, their use as a reinforcing material for thermoplastic resins and the like has attracted attention (see, for example, Patent Document 1).

[0003] On the other hand, since cellulose nanofibers are hydrophilic, they have a problem that it is difficult to uniformly disperse them in a dispersion medium such as an organic solvent, and the scope of application is limited. Therefore, for example, conventionally, vinyl organic acid is reacted with cellulose nanofibers in a water-containing state, and then the product is recovered to impart hydrophobicity to the cellulose nanofibers, thereby improving the dispersibility in an organic solvent. It has been proposed (see, for example, Patent Document 2). Hereinafter, a cellulose nanofiber to which desired properties such as hydrophobicity are imparted to a natural-derived cellulose nanofiber obtained from plant fibers or the like may be referred to as a "modified cellulose nanofiber".

[0004] However, the modified cellulose nanofibers described in Patent Document 2 have strict reaction conditions between cellulose nanofibers and vinyl organic acids, and the production process is complicated, necessitating improvements in manufacturing efficiency. Furthermore, in modified cellulose nanofibers modified with vinyl organic acids, the molecular structure of the cellulose nanofiber skeleton itself changes depending on the degree of modification, leaving room for improvement in terms of improving the hydrophobicity of the modified cellulose nanofibers and, consequently, improving their dispersibility in dispersion media such as organic solvents. Therefore, the modified cellulose nanofibers described in Patent Document 2 still need improvement in terms of obtaining dispersions with excellent dispersibility of cellulose nanofibers, and the problem of limited application range for cellulose nanofibers remains.

[0005] Furthermore, as a technique for imparting hydrophobicity to cellulose nanofibers, it has been proposed to bond two types of modifying groups to the surface of cellulose nanofibers: a modifying group selected for its wettability, such as aromatic groups, and a modifying group selected for its steric repulsion and hydrophobicity, such as polyalkylene glycol groups. This method allows for the acquisition of hydrophobic cellulose nanofibers with a small mass of modifying groups. However, modified cellulose nanofibers produced using two types of modifying groups, such as aromatic groups and polyalkylene glycol groups, have a complex chemical structure, and there is still a need for improvement in obtaining dispersions with excellent dispersibility of cellulose nanofibers. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-11392 [Patent Document 2] International Publication No. 2016 / 010016 [Overview of the project] [Problems that the invention aims to solve]

[0007] In view of the above circumstances, the present invention aims to provide a method for producing a cellulose nanofiber composition that exhibits excellent dispersibility of cellulose nanofibers and can easily expand the range of applications of cellulose. [Means for solving the problem]

[0008] The gist of the present invention is as follows: [1] A dispersion medium preparation step, in which a dispersion medium is prepared, A cellulose derivative addition step is performed in which a cellulose derivative is added to the prepared dispersion medium to prepare a cellulose derivative-containing solution, A cellulose nanofiber addition step is performed by adding cellulose nanofibers to the cellulose derivative-containing solution, A method for producing a cellulose nanofiber composition containing the above. [2] A dispersion medium preparation step, in which a dispersion medium is prepared, A cellulose nanofiber addition step is performed to prepare a cellulose nanofiber-containing dispersion medium by adding cellulose nanofibers to the prepared dispersion medium, A cellulose derivative addition step is to add a cellulose derivative to the cellulose nanofiber-containing dispersion medium, A method for producing a cellulose nanofiber composition containing the above. [3] A dispersion medium preparation step, in which a dispersion medium is prepared, A cellulose component addition step is to add a cellulose derivative and cellulose nanofibers as cellulose components to the prepared dispersion medium, A method for producing a cellulose nanofiber composition containing the above. [4] A method for producing a cellulose nanofiber composition according to any one of [1] to [3], wherein the cellulose derivative comprises at least one selected from the group consisting of hydroxyalkylcellulose and alkylcellulose. [5] A method for producing the cellulose nanofiber composition according to [4], wherein the cellulose derivative is hydroxyalkylcellulose. [6] A method for producing a cellulose nanofiber composition according to [4] or [5], wherein the hydroxyalkyl cellulose is hydroxypropyl cellulose. [7] A method for producing a cellulose nanofiber composition according to any one of [1] to [6], wherein 5.0 parts by mass or more and 5000 parts by mass or less of the cellulose derivative is added to 100 parts by mass of the cellulose nanofiber. [8] A method for producing a cellulose nanofiber composition according to any one of [1] to [6], wherein 10 parts by mass or more and 2000 parts by mass or less of the cellulose derivative are added to 100 parts by mass of the cellulose nanofiber. [9] A method for producing a cellulose nanofiber composition according to any one of [1] to [8], wherein 0.5 parts by mass or more and 120 parts by mass or less of the cellulose derivative are added to 100 parts by mass of the dispersion medium.

[10] A method for producing a cellulose nanofiber composition according to any one of [1] to [9] which is a dispersion of cellulose nanofibers.

[11] A method for producing a cellulose nanofiber composition according to any one of [1] to

[10] , wherein the cellulose nanofiber is a cellulose nanofiber that has been dried.

[12] A method for producing a cellulose nanofiber composition according to

[11] , wherein the drying treatment is freeze-drying.

[13] A method for producing the cellulose nanofiber composition according to

[10] , wherein the average value of the transmittance of the dispersion of cellulose nanofibers at a wavelength of 400 nm at a rotation speed of 1000 rpm of the stirring means is 0.30 or less.

[14] A method for producing a cellulose nanofiber composition according to

[10] or

[13] , wherein the standard deviation of the transmittance of the dispersion of cellulose nanofibers at a wavelength of 400 nm at a rotation speed of 1000 rpm of the stirring means is 0.10 or less.

[0009] The cellulose nanofibers used in the method for producing the cellulose nanofiber composition of the present invention are not modified cellulose nanofibers that have been given desired properties such as hydrophobicity (hereinafter, cellulose nanofibers that are not modified cellulose nanofibers may simply be referred to as "cellulose nanofibers"). In other words, the cellulose nanofibers used in the method for producing the cellulose nanofiber composition of the present invention have a hydrophilic chemical structure. Furthermore, the cellulose nanofibers are cellulose fibers with an average fiber diameter of less than 1.0 μm, that is, an average fiber diameter on the nanoscale.

[0010] Furthermore, the cellulose derivative used in the method for producing the cellulose nanofiber composition of the present invention is dissolved in the dispersion medium within the obtained cellulose nanofiber composition. It is believed that because the cellulose derivative is dissolved in the dispersion medium within the cellulose nanofiber composition, the hydroxyl groups of the cellulose derivative interact with the hydroxyl groups of the cellulose nanofibers in the cellulose nanofiber composition, resulting in a state where the cellulose derivative is coordinated to the cellulose nanofibers.

[0011] "The transmittance of light at a wavelength of 400 nm in a dispersion of cellulose nanofibers at a stirring speed of 1000 rpm" refers to the transmittance of light at a path length of 1 cm and wavelength of 400 nm measured at the center of the cellulose nanofiber dispersion, when 2.0 ml of a dispersion of cellulose nanofibers (prepared by adding a predetermined amount of cellulose derivative to 0.1 g of cellulose nanofibers per 20 ml of dispersion medium) is placed in a 4.5 ml container and stirred at a rotation speed of 1000 rpm using a stirrer (stirring bar) with a diameter of 9 mm and a height of 6.5 mm under conditions of 25°C. The transmittance measurement result for a single measurement is calculated as the average transmittance over 180 seconds, measured every 2 seconds from the start of stirring. "Average transmittance" refers to the average of the average transmittance measurements from three measurements. Furthermore, "standard deviation of transmittance" refers to the average of the standard deviations obtained from three average transmittance measurements, calculated by taking a single average transmittance measurement, that is, a measurement of transmittance taken every two seconds for 180 seconds. [Effects of the Invention]

[0012] The present invention provides a method for producing a cellulose nanofiber composition that has excellent dispersibility of cellulose nanofibers and can easily expand the range of applications of cellulose. This method includes: a dispersion medium preparation step of preparing a dispersion medium; a cellulose derivative addition step of adding a cellulose derivative to the prepared dispersion medium to prepare a cellulose derivative-containing solution; and a cellulose nanofiber addition step of adding cellulose nanofibers to the cellulose derivative-containing solution; or a dispersion medium preparation step of preparing a dispersion medium; a cellulose nanofiber addition step of adding cellulose nanofibers to the prepared dispersion medium to prepare a cellulose nanofiber-containing dispersion medium; or a dispersion medium preparation step of preparing a dispersion medium; and a cellulose component addition step of adding a cellulose derivative and cellulose nanofibers as cellulose components to the prepared dispersion medium. Therefore, the cellulose nanofiber composition obtained by the manufacturing method of the present invention can uniformly disperse the cellulose nanofibers in the hydrophobic substance to which it is applied, thus easily expanding the range of applications for cellulose.

[0013] Furthermore, according to the method for producing the cellulose nanofiber composition of the present invention, there is no need to pre-modify the cellulose nanofibers to be hydrophobic. As the skeleton of the cellulose nanofibers is maintained, the properties of the cellulose nanofibers can be reliably imparted to the target object.

[0014] According to the method for producing the cellulose nanofiber composition of the present invention, by including at least one cellulose derivative selected from the group consisting of hydroxyalkyl cellulose and alkyl cellulose, excellent dispersibility of the cellulose nanofibers in the cellulose nanofiber composition can be surely obtained.

[0015] According to the method for producing the cellulose nanofiber composition of the present invention, when the cellulose derivative is hydroxyalkyl cellulose, the dispersibility of the cellulose nanofibers in the cellulose nanofiber composition is more surely improved.

[0016] According to the method for producing the cellulose nanofiber composition of the present invention, when the hydroxyalkyl cellulose is hydroxypropyl cellulose, the dispersibility of the cellulose nanofibers in the cellulose nanofiber composition is further improved.

[0017] According to the method for producing the cellulose nanofiber composition of the present invention, by adding 5.0 parts by mass or more and 5000 parts by mass or less of the cellulose derivative with respect to 100 parts by mass of the cellulose nanofibers, excellent dispersibility of the cellulose nanofibers in the cellulose nanofiber composition can be surely obtained. Further, according to the method for producing the cellulose nanofiber composition of the present invention, by adding 10 parts by mass or more and 2000 parts by mass or less of the cellulose derivative with respect to 100 parts by mass of the cellulose nanofibers, excellent dispersibility of the cellulose nanofibers in the cellulose nanofiber composition can be more surely obtained.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a photograph showing the dispersibility of the cellulose nanofiber composition in Comparative Example 1 (left), Example 1 (center), and Example 2 (right). [Figure 2] FIG. 2 is a photograph showing the dispersibility of the cellulose nanofiber composition in Comparative Example 1 (left), Example 3 (center), and Example 4 (right). [Figure 3] Figure 3 shows photographs illustrating the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 5 (center), and Example 6 (right). [Figure 4] Figure 4 shows photographs illustrating the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 7 (center), and Example 8 (right). [Figure 5] Figure 5 shows photographs illustrating the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 9 (center), and Example 10 (right). [Figure 6] Figure 6 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 1 (bottom left row), and Example 2 (bottom right row). [Figure 7] Figure 7 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 3 (bottom left row), and Example 4 (bottom right row). [Figure 8] Figure 8 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 5 (bottom left row), and Example 6 (bottom right row). [Figure 9] Figure 9 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 7 (bottom left row), and Example 8 (bottom right row). [Figure 10] Figure 10 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 9 (bottom left row), and Example 10 (bottom right row). [Modes for carrying out the invention]

[0019] Details of the method for producing the cellulose nanofiber composition of the present invention will be described below. First, a first aspect of the method for producing the cellulose nanofiber composition of the present invention will be described.

[0020] <First aspect of a method for producing a cellulose nanofiber composition> A first aspect of the method for producing a cellulose nanofiber composition includes (1) a dispersion medium preparation step of preparing a dispersion medium, (2) a cellulose derivative addition step of adding a cellulose derivative to the prepared dispersion medium to prepare a cellulose derivative-containing solution, and (3) a cellulose nanofiber addition step of adding cellulose nanofibers to the cellulose derivative-containing solution. In the first aspect, a predetermined amount of cellulose derivative is added to the dispersion medium, and then cellulose nanofibers are added to produce a cellulose nanofiber composition. In the cellulose nanofiber composition obtained by the method for producing a cellulose nanofiber composition of the present invention, the cellulose derivative is dissolved in the dispersion medium, and the cellulose nanofibers are dispersed in the dispersion medium.

[0021] According to the first aspect of the method for producing a cellulose nanofiber composition, a cellulose nanofiber composition with excellent dispersibility of cellulose nanofibers and the ability to easily expand the range of applications of cellulose can be produced by the simple manufacturing process described in (1) to (3) above. The first aspect of the method for producing a cellulose nanofiber composition of the present invention makes it possible to produce a composition with excellent dispersibility of cellulose nanofibers without having to prepare modified cellulose nanofibers that have been given properties such as hydrophobicity. As a result, the resulting cellulose nanofiber composition can uniformly disperse cellulose nanofibers in the hydrophobic substance to which it is applied, and as a result, the range of applications of cellulose can be easily expanded. Furthermore, since it is not necessary to modify the cellulose nanofibers to be hydrophobic in advance, the skeleton of the cellulose nanofibers is maintained, and the properties of the cellulose nanofibers can be reliably imparted to the target substance.

[0022] (1) Dispersion medium preparation process The dispersion medium functions as a medium for dispersing cellulose nanofibers in the cellulose nanofiber composition and for dissolving cellulose derivatives. Examples of dispersion liquids prepared in the dispersion medium preparation step include organic solvents. Examples of organic solvents include C1-C5 alcohols such as tetrahydrofuran, acetone, ethanol, and propanol, cyclohexanol, propylene glycol, cyclohexanone, dioxane, cellosolve, butyl cellosolve, glacial acetic acid, formic acid, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, methylene chloride, chloroform, a mixture of benzene:methanol (1:1 volume ratio), a mixture of toluene:ethanol (3:2 volume ratio), and a mixture of glycerin:water (3:7 volume ratio). Water can also be used as the dispersion medium. These various dispersion media may be used individually or in combination of two or more. In addition, a solution of organic solvents that are miscible with water may be used as the dispersion liquid.

[0023] (2) Cellulose derivative addition step The cellulose derivative addition step involves adding a predetermined amount of cellulose derivative to a dispersion medium to prepare a cellulose derivative-containing solution in which the cellulose derivative is dissolved in the dispersion medium. The cellulose derivative added to the dispersion medium is a different component from cellulose nanofibers in that it is a compound obtained by chemically modifying cellulose. The cellulose derivative is dissolved in the dispersion medium within the cellulose nanofiber composition. Because the cellulose derivative is dissolved in the dispersion medium within the cellulose nanofiber composition, the hydroxyl groups of the cellulose derivative interact with the hydroxyl groups of the cellulose nanofibers that are added to the cellulose derivative-containing solution in the subsequent step (3) cellulose nanofiber addition step, resulting in a state in which the cellulose derivative is coordinated to the cellulose nanofibers. Furthermore, since both cellulose nanofibers and cellulose derivatives have a cellulose skeleton, their molecular structures are similar. Therefore, because cellulose nanofibers have a high affinity for cellulose derivatives, it is thought that they are more likely to be coordinated to the cellulose nanofibers. Because the cellulose derivative is coordinated to the cellulose nanofibers, the surfactant properties of the cellulose derivative are exhibited, and it is thought that the cellulose nanofibers have excellent dispersibility within the cellulose nanofiber composition.

[0024] Furthermore, since the cellulose nanofiber composition obtained by the manufacturing method of the present invention uses a cellulose derivative, which is a biocompatible material, it can reduce environmental impact and has excellent safety.

[0025] The cellulose derivative is not particularly limited as long as it is a derivative obtained by a chemical reaction of at least some of the hydroxyl groups of cellulose, and examples include hydroxyalkylcellulose, alkylcellulose, carboxyalkylcellulose, and hydroxyalkylalkylcellulose. Of these, hydroxyalkylcellulose and alkylcellulose are preferred because they can reliably obtain excellent dispersibility of cellulose nanofibers in the cellulose nanofiber composition, and hydroxyalkylcellulose is particularly preferred because it more reliably improves the dispersibility of cellulose nanofibers. As the cellulose derivative, for example, hydroxyalkylcellulose and alkylcellulose may be used in combination, or either may be used alone.

[0026] Examples of hydroxyalkylcellulose include hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxybutylcellulose, hydroxypentylcellulose, and hydroxyhexylcellulose. These compounds may be used individually or in combination of two or more. Of these, hydroxyethylcellulose and hydroxypropylcellulose are preferred, and hydroxypropylcellulose is particularly preferred, as they further improve the dispersibility of cellulose nanofibers in the cellulose nanofiber composition.

[0027] Examples of alkylcelluloses include methylcellulose, ethylcellulose, propylcellulose, butylcellulose, pentylcellulose, and hexylcellulose. These compounds may be used individually or in combination of two or more. Of these, methylcellulose and ethylcellulose are preferred, and ethylcellulose is particularly preferred, as they allow for more reliable dispersibility of cellulose nanofibers.

[0028] Examples of carboxyalkylcellulose include carboxymethylcellulose, carboxyethylcellulose, carboxypropylcellulose, carboxybutylcellulose, carboxypentylcellulose, and carboxyhexylcellulose.

[0029] Hydroxyalkylalkylcellulose is a type of cellulose having both a hydroxyalkyl and an alkyl group. Examples of hydroxyalkylalkylcellulose include cellulose having both a hydroxymethyl and an alkyl group, such as hydroxymethylmethylcellulose, hydroxymethylethylcellulose, hydroxymethylpropylcellulose, and hydroxymethylbutylcellulose; cellulose having both a hydroxyethyl and an alkyl group, such as hydroxyethylmethylcellulose, hydroxyethylethylcellulose, hydroxyethylpropylcellulose, and hydroxyethylbutylcellulose; cellulose having both a hydroxypropyl and an alkyl group, such as hydroxypropylmethylcellulose, hydroxypropylethylcellulose, hydroxypropylpropylcellulose, and hydroxypropylbutylcellulose; and cellulose having both a hydroxybutyl and an alkyl group, such as hydroxybutylmethylcellulose, hydroxybutylethylcellulose, hydroxybutylpropylcellulose, and hydroxybutylbutylcellulose.

[0030] One method for preparing a cellulose derivative-containing solution is to add the cellulose derivative to a dispersion medium and stir under predetermined stirring conditions to dissolve the cellulose derivative in the dispersion medium. The stirring conditions can be appropriately selected depending on the molecular weight and amount of the cellulose derivative, the size of the stirring container, the type of stirrer, etc., and are not particularly limited, but examples include a stirring temperature of 10°C to 60°C, a stirring time of 1 minute to 120 minutes, and a stirring speed of 600 rpm to 1350 rpm. The stirring time and stirring speed can be set appropriately depending on the type of stirrer, the size of the stirring container, the molecular weight and amount of the cellulose derivative, etc. Furthermore, the stirring means are not particularly limited and examples include stirrers and impellers.

[0031] The amount of cellulose derivative added to the dispersion medium is not particularly limited, but the lower limit is preferably 0.5 parts by mass, more preferably 2.0 parts by mass, and especially preferably 3.0 parts by mass, per 100 parts by mass of the dispersion medium, in order to reliably obtain excellent dispersibility of cellulose nanofibers. On the other hand, the upper limit of the amount of cellulose derivative added to the dispersion medium is preferably 120 parts by mass, more preferably 75 parts by mass, and especially preferably 50 parts by mass, per 100 parts by mass of the dispersion medium, in order to reliably impart the properties of cellulose nanofibers to the target.

[0032] (3) Cellulose nanofiber addition process The cellulose nanofiber addition step involves adding cellulose nanofibers to the cellulose derivative-containing solution obtained as described above. By adding cellulose nanofibers to the cellulose derivative-containing solution and dispersing the cellulose nanofibers in the solution, a cellulose nanofiber composition can be produced.

[0033] The cellulose nanofibers used in the method for producing the cellulose nanofiber composition of the present invention are hydrophilic cellulose nanofibers that have not undergone modification treatment, rather than modified cellulose nanofibers that have been given desired properties such as hydrophobicity. Therefore, when adding cellulose nanofibers to a cellulose derivative-containing solution, it is not necessary to modify the cellulose nanofibers to give them desired properties such as hydrophobicity. In addition, dried cellulose nanofibers may be used as cellulose nanofibers if necessary. In this case, the cellulose nanofibers (i.e., dried cellulose nanofibers) are dried before being added to the cellulose derivative-containing solution. The drying conditions are not particularly limited and include air drying, natural drying, freeze drying, etc., with freeze drying being particularly preferred.

[0034] Examples of cellulose nanofibers include cellulose derived from natural products. For example, cellulose nanofibers can be obtained by defibrating a cellulose precursor derived from natural products, which serves as the raw material, to form nanofibers. Examples of cellulose precursors that serve as the raw material for cellulose nanofibers include plant fibers such as pulp. The method for defibrating the cellulose precursor is not particularly limited and can include defibration using a mixer, high-speed homomixer, ultrasonic homogenizer, low-pressure homogenizer, high-pressure homogenizer, high-speed rotary mixer, grinder, freeze-drying, media mill, ball mill, etc.

[0035] Cellulose nanofibers, obtained by defibrating a cellulose precursor, can be acquired, for example, as a cellulose nanofiber aqueous dispersion in which cellulose nanofibers are dispersed in water. Cellulose nanofibers can then be obtained by performing a drying process to remove water from the cellulose nanofiber aqueous dispersion.

[0036] Cellulose nanofibers have an average fiber diameter of less than 1.0 μm. While the size of the cellulose is not particularly limited for cellulose nanofibers with an average fiber diameter of less than 1.0 μm, from the viewpoint of expanding the application range of cellulose nanofibers, an average fiber diameter of 4 nm to 100 nm is preferred, and 10 nm to 50 nm is particularly preferred. Similarly, while the average fiber length of cellulose nanofibers is not particularly limited, from the viewpoint of expanding the application range of cellulose nanofibers, 20 μm to 200 μm is preferred, and 50 μm to 150 μm is particularly preferred. The average fiber diameter and average fiber length of cellulose nanofibers can be measured, for example, by scanning probe microscopy or nitrogen adsorption for the average fiber diameter, and by electron microscopy (transmission electron microscope (TEM), scanning electron microscope (SEM)) or scanning probe microscopy for the average fiber length.

[0037] One method for dispersing cellulose nanofibers in a cellulose derivative-containing solution is to add cellulose nanofibers to the cellulose derivative-containing solution and stir under predetermined stirring conditions. The stirring conditions can be appropriately selected depending on the molecular weight and amount of cellulose nanofibers added, the size of the stirring container, the type of stirrer, etc., and are not particularly limited, but examples include a stirring temperature of 10°C to 60°C, a stirring time of 1 minute to 120 minutes, and a stirring speed of 600 rpm to 1350 rpm. The stirring time and stirring speed can be set appropriately depending on the type of stirrer, the size of the stirring container, the molecular weight and amount of cellulose nanofibers added, etc. Furthermore, the stirring means are not particularly limited and examples include stirrers and stirring blades.

[0038] The amount of cellulose nanofiber added to the dispersion medium is not particularly limited and can be appropriately selected depending on the usage conditions of the cellulose nanofiber composition and the dispersion state of the cellulose nanofiber in the dispersion medium.

[0039] Furthermore, the proportion of cellulose derivative added to cellulose nanofibers is not particularly limited, but the lower limit is preferably 5.0 parts by mass of cellulose derivative per 100 parts by mass of cellulose nanofibers, in order to reliably obtain excellent dispersibility of cellulose nanofibers in the cellulose nanofiber composition, more preferably 10 parts by mass to further reliably obtain excellent dispersibility of cellulose nanofibers, more preferably 30 parts by mass, even more preferably 100 parts by mass, and particularly preferably 200 parts by mass, in order to further improve the dispersibility of cellulose nanofibers in the cellulose nanofiber composition. On the other hand, the upper limit of the proportion of cellulose derivative added to cellulose nanofibers is preferably 5,000 parts by mass of cellulose derivative per 100 parts by mass of cellulose nanofibers, in order to reliably impart the properties of cellulose nanofibers to the target while reliably obtaining excellent dispersibility of cellulose nanofibers, more preferably 4,000 parts by mass, even more preferably 3,000 parts by mass, and particularly preferably 2,000 parts by mass, in order to further reliably obtain excellent dispersibility of cellulose nanofibers.

[0040] <Second aspect of the method for producing a cellulose nanofiber composition> A second aspect of the method for producing a cellulose nanofiber composition includes (1) a dispersion medium preparation step of preparing a dispersion medium, (2) a cellulose nanofiber addition step of adding cellulose nanofibers to the prepared dispersion medium to prepare a cellulose nanofiber-containing dispersion medium, and (3) a cellulose derivative addition step of adding a cellulose derivative to the cellulose nanofiber-containing dispersion medium. In the second aspect, a predetermined amount of cellulose nanofibers is added to the dispersion medium to disperse the cellulose nanofibers in the dispersion medium to prepare a cellulose nanofiber-containing dispersion medium, and then a cellulose derivative is added to the cellulose nanofiber-containing dispersion medium and dissolved to produce a cellulose nanofiber composition. Therefore, the second aspect differs from the first aspect in that the order of addition of cellulose nanofibers and cellulose derivatives to the dispersion medium is different, but in other respects, it is the same as the first aspect described above, including the amount of each component to be added and the stirring conditions.

[0041] In the second embodiment of the method for producing a cellulose nanofiber composition, the resulting cellulose nanofiber composition is in which the cellulose derivative is dissolved in the dispersion medium and the cellulose nanofibers are dispersed in the dispersion medium.

[0042] In the second embodiment of the method for producing a cellulose nanofiber composition, a cellulose nanofiber composition with excellent dispersibility of cellulose nanofibers and the ability to easily expand the range of applications of cellulose can be produced by the simple manufacturing process described in (1) to (3) above. In the second embodiment of the method for producing a cellulose nanofiber composition of the present invention, a composition with excellent dispersibility of cellulose nanofibers can be produced without preparing modified cellulose nanofibers that have been given properties such as hydrophobicity. As a result, the resulting cellulose nanofiber composition can uniformly disperse cellulose nanofibers in the hydrophobic substance to which it is applied, and the range of applications of cellulose can be easily expanded. Furthermore, since it is not necessary to modify the cellulose nanofibers to be hydrophobic in advance, the skeleton of the cellulose nanofibers is maintained, and the properties of the cellulose nanofibers can be reliably imparted to the target substance.

[0043] <Third aspect of the method for producing a cellulose nanofiber composition> A third aspect of the method for producing a cellulose nanofiber composition includes (1) a dispersion medium preparation step of preparing a dispersion medium, and (2) a cellulose component addition step of adding a cellulose derivative and cellulose nanofibers as cellulose components to the prepared dispersion medium. In the third aspect, a cellulose nanofiber composition is produced by adding cellulose nanofibers and a cellulose derivative to a dispersion medium, dissolving the cellulose derivative in the dispersion medium, and dispersing the cellulose nanofibers in the dispersion medium. Therefore, the third aspect differs from the first aspect in that the cellulose nanofibers and cellulose derivatives are added to the dispersion medium simultaneously, but in other respects, it is the same as the first aspect described above, including the amount of each component added and the stirring conditions.

[0044] In the third embodiment, cellulose nanofibers and cellulose derivatives may be added to the dispersion medium via different input routes. Alternatively, a cellulose component containing cellulose nanofibers and cellulose derivatives may be prepared first, and this cellulose component may be added to the dispersion medium.

[0045] In the third embodiment of the method for producing a cellulose nanofiber composition, the resulting cellulose nanofiber composition is in a state where the cellulose derivative is dissolved in the dispersion medium and the cellulose nanofibers are dispersed in the dispersion medium.

[0046] In the third aspect of the method for producing a cellulose nanofiber composition, a cellulose nanofiber composition with excellent dispersibility of cellulose nanofibers and the ability to easily expand the range of applications of cellulose can be produced using the simple manufacturing process described in (1) and (2) above. In the third aspect of the method for producing a cellulose nanofiber composition of the present invention, a composition with excellent dispersibility of cellulose nanofibers can be produced without preparing modified cellulose nanofibers that have been given properties such as hydrophobicity. As a result, the resulting cellulose nanofiber composition can uniformly disperse cellulose nanofibers in the hydrophobic substance to which it is applied, and the range of applications of cellulose can be easily expanded. Furthermore, since it is not necessary to modify the cellulose nanofibers to be hydrophobic in advance, the skeleton of the cellulose nanofibers is maintained, and the properties of the cellulose nanofibers can be reliably imparted to the target substance.

[0047] In the cellulose nanofiber composition obtained by the manufacturing method of the present invention, the cellulose derivative is dissolved in the dispersion medium, and the cellulose nanofibers are dispersed in the dispersion medium. As a result, the cellulose derivative is coordinated to the cellulose nanofibers, and the cellulose nanofibers in the cellulose nanofiber composition have excellent dispersibility. Therefore, an embodiment of the cellulose nanofiber composition obtained by the manufacturing method of the present invention is a dispersion of cellulose nanofibers, for example, a dispersion in which cellulose nanofibers are dispersed in an organic solvent.

[0048] The dispersion state of cellulose nanofibers in a dispersion of cellulose nanofibers obtained by the manufacturing method of the present invention can be evaluated by measuring the transmittance of light at a wavelength of 400 nm. The lower the dispersibility of cellulose nanofibers in the dispersion and the more aggregated the cellulose nanofibers are at the bottom of the dispersion, the higher the transmittance of light at a wavelength of 400 nm measured in the center of the dispersion in the vertical direction. On the other hand, the higher the dispersibility of cellulose nanofibers in the dispersion and the reduced aggregation of cellulose nanofibers, i.e., the more uniform the dispersion of cellulose nanofibers, the lower the transmittance of light at a wavelength of 400 nm measured in the center of the dispersion in the vertical direction.

[0049] The average value of the transmittance of light at a wavelength of 400 nm in a dispersion of cellulose nanofibers at a stirring speed of 1000 rpm is preferably 0.30 or less, more preferably 0.20 or less, and particularly preferably 0.10 or less, as this ensures excellent dispersibility of the cellulose nanofibers. A lower limit of the above-mentioned average value of light transmittance can be, for example, 0.02.

[0050] The dispersion state of cellulose nanofibers in a dispersion of cellulose nanofibers obtained by the manufacturing method of the present invention can be evaluated by measuring the standard deviation of light transmittance at a wavelength of 400 nm at a stirring speed of 1000 rpm. The lower the dispersibility of cellulose nanofibers in the dispersion and the more easily the cellulose nanofibers aggregate at the bottom of the dispersion, the lower the dispersion stability of the cellulose nanofibers, and therefore the higher the standard deviation of transmittance. On the other hand, the lower the aggregation state of cellulose nanofibers and the more uniform the dispersion of cellulose nanofibers in the dispersion, the higher the dispersion stability of the cellulose nanofibers, and therefore the lower the standard deviation of transmittance.

[0051] The standard deviation of the transmittance of light at a wavelength of 400 nm in a dispersion of cellulose nanofibers at a stirring speed of 1000 rpm is preferably 0.10 or less, more preferably 0.06 or less, in that excellent dispersibility of cellulose nanofibers is reliably obtained, even more preferably 0.03 or less, and particularly preferably 0.02 or less, in that the dispersibility of cellulose nanofibers is further improved.

[0052] <Molded product of cellulose nanofiber film> A cellulose nanofiber molded article of a predetermined shape can be obtained by forming a cellulose nanofiber composition obtained by the manufacturing method of the present invention into a predetermined shape, and then removing the dispersion medium from the cellulose nanofiber composition by drying or other means. In the cellulose nanofiber composition obtained by the manufacturing method of the present invention, the aggregation state of cellulose nanofibers is reduced and the dispersion of cellulose nanofibers is made uniform. Therefore, the cellulose nanofiber molded article obtained by removing the dispersion medium from the cellulose nanofiber composition obtained by the manufacturing method of the present invention has a uniform distribution of cellulose nanofibers and a smooth surface. Furthermore, the cellulose nanofiber composition obtained by the manufacturing method of the present invention has not only excellent dispersibility of cellulose nanofibers but also appropriate fluidity, so a film-like molded article can be easily obtained. [Examples]

[0053] Next, embodiments of the present invention will be described, but the present invention is not limited to these examples unless it exceeds the spirit of the invention.

[0054] <Manufacturing of Cellulose Nanofiber Composition> Example 1 A cellulose nanofiber aqueous dispersion (average fiber length 100 μm, average fiber diameter 30-40 nm, "CellFim C-100 (approximately 95% by mass)" manufactured by Mori Machinery Co., Ltd.) was freeze-dried to obtain solid-phase cellulose nanofibers. 0.01 g of hydroxypropyl cellulose (cellulose derivative) was added to 20 ml of tetrahydrofuran (dispersion medium) to dissolve the hydroxypropyl cellulose in the tetrahydrofuran and prepare a cellulose derivative-containing solution. 0.1 g of freeze-dried cellulose nanofibers (mass ratio of cellulose nanofibers to hydroxypropyl cellulose = 1:0.1) was added to the cellulose derivative-containing solution and stirred for 24 hours to produce a cellulose nanofiber composition, which is a dispersion of cellulose nanofibers.

[0055] Example 2 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.03 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:0.3) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0056] Example 3 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.05 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:0.5) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0057] Example 4 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.1 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:1) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0058] Example 5 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.3 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:3) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0059] Example 6 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.5 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:5) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0060] Example 7 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 0.7 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:7) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0061] Example 8 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 1.0 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:10) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0062] Example 9 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 1.5 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:15) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0063] Example 10 A cellulose nanofiber composition was prepared in the same manner as in Example 1, except that 2.0 g of hydroxypropyl cellulose (cellulose derivative) and 0.1 g of freeze-dried cellulose nanofiber (mass ratio of cellulose nanofiber to hydroxypropyl cellulose = 1:20) were added to 20 ml of tetrahydrofuran (dispersion medium).

[0064] Comparative Example 1 Except for not adding hydroxypropylcellulose (a cellulose derivative), A cellulose nanofiber composition was prepared in the same manner as in Example 1.

[0065] <Evaluation Criteria> (1) Dispersibility of cellulose nanofiber composition For the cellulose nanofiber compositions of Examples 1 to 10 and Comparative Example 1, 0.5 ml was taken, and 6 ml of tetrahydrofuran was added to prepare a sample for dispersibility evaluation. The dispersion state of the cellulose nanofibers was observed visually and evaluated as follows. ◎: The dispersion state of cellulose nanofibers is excellent. ○: Although some aggregation of cellulose nanofibers is observed, the dispersion state is good. ×: Many of the cellulose nanofibers are in an aggregated state, and the dispersibility of the cellulose nanofibers is not observed.

[0066] (2) Formability of films obtained from cellulose nanofiber compositions The cellulose nanofiber compositions of Examples 1 to 10 and Comparative Example 1 were spread on a petri dish and left in a 35°C air bath for 4 hours to volatilize the tetrahydrofuran and obtain cellulose nanofiber films. The molding state of the cellulose nanofiber films was visually observed and evaluated as follows. ◎: The surface of the cellulose nanofiber film is smooth, and there is almost no unevenness in the cellulose nanofibers, indicating that the molding condition of the cellulose nanofiber film is excellent. ○: The surface condition of the cellulose nanofiber film is slightly rough, and some unevenness in the cellulose nanofibers is visible, but the molding condition is good. ×: Cellulose nanofiber film cannot be formed, or there are many irregularities in the cellulose nanofibers, and moldability into a cellulose nanofiber film is not observed.

[0067] (3) Transmittance of light with a wavelength of 400 nm For the cellulose nanofiber compositions of Examples 1-10 and Comparative Example 1, 2.0 ml was placed in a 4.5 ml container and stirred at 1000 rpm using a stirrer with a diameter of 9 mm and a height of 6.5 mm at 25°C. During stirring, 400 nm light was shone onto the central part of the cellulose nanofiber composition in the height direction with a path length of 1 cm. The transmittance of 400 nm light was measured from the radiant intensity of the incident light (I0) and the radiant intensity of the light transmitted through the cellulose nanofiber composition (I). The transmittance measurement for one test was calculated as the average value (average transmittance) of the transmittance measured at 2-second intervals over 180 seconds from the start of stirring. The average value of the average transmittance (n=3) obtained by repeating this three times was taken as the transmittance of 400 nm light.

[0068] (4) Standard deviation of transmittance For each average transmittance measurement taken every 2 seconds over a 180-second period, the standard deviation was calculated. The standard deviation of transmittance was then determined from the average of the standard deviations obtained from three average transmittance measurements.

[0069] The evaluation results are shown in Table 1 below. Figure 1 is a photograph showing the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 1 (center), and Example 2 (right). Figure 2 is a photograph showing the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 3 (center), and Example 4 (right). Figure 3 is a photograph showing the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 5 (center), and Example 6 (right). Figure 4 is a photograph showing the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 7 (center), and Example 8 (right). Figure 5 is a photograph showing the dispersibility of the cellulose nanofiber compositions in Comparative Example 1 (left), Example 9 (center), and Example 10 (right). Figure 6 is a photograph showing the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 1 (bottom left), and Example 2 (bottom right). Figure 7 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 3 (bottom left), and Example 4 (bottom right). Figure 8 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 5 (bottom left), and Example 6 (bottom right). Figure 9 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 7 (bottom left), and Example 8 (bottom right). Figure 10 shows photographs illustrating the moldability of the cellulose nanofiber compositions in Comparative Example 1 (top row), Example 9 (bottom left), and Example 10 (bottom right).

[0070] [Table 1]

[0071] From Table 1 and Figures 1-5 above, the cellulose nanofiber compositions of Examples 1-10, prepared by adding cellulose derivatives and cellulose nanofibers to the dispersion medium, exhibited excellent dispersibility of cellulose nanofibers. In particular, in Examples 4-10, where the cellulose nanofiber composition was prepared with a mass ratio of cellulose nanofibers to hydroxypropyl cellulose of 1:1 to 1:20, the dispersibility of cellulose nanofibers was further improved.

[0072] Furthermore, as can be seen from Table 1 and Figures 6-10 above, the cellulose nanofiber compositions of Examples 1-10 exhibited excellent moldability, making it easy to expand the range of applications for cellulose. In particular, in Examples 4-10, where the cellulose nanofiber composition was produced with a mass ratio of cellulose nanofiber to hydroxypropyl cellulose of 1:1 to 1:20, the moldability was further improved.

[0073] Furthermore, in the manufacturing methods of Examples 1 to 10, in which the transmittance of the cellulose nanofiber composition at a wavelength of 400 nm was reduced to 0.176 or less and the standard deviation of transmittance was reduced to 0.075 or less, the dispersibility and moldability of the cellulose nanofibers were excellent. In particular, in the manufacturing methods of Examples 4 to 10, in which the transmittance of the cellulose nanofiber composition at a wavelength of 400 nm was reduced to 0.095 or less and the standard deviation of transmittance was reduced to 0.014 or less, the dispersibility and moldability of the cellulose nanofibers were further improved.

[0074] On the other hand, as can be seen from Table 1 and Figures 1-5 above, in Comparative Example 1, in which a cellulose nanofiber composition was produced without the addition of a cellulose derivative, dispersibility of the cellulose nanofibers could not be obtained. Furthermore, as can be seen from Table 1 and Figures 6-10 above, the cellulose nanofiber composition of Comparative Example 1 did not exhibit moldability, making it difficult to broaden the range of applications of cellulose. In the cellulose nanofiber composition obtained by the manufacturing method of Comparative Example 1, the transmittance of light at a wavelength of 400 nm was 0.661, and the standard deviation of transmittance was 1.096. [Industrial applicability]

[0075] The method for producing the cellulose nanofiber composition of the present invention provides a cellulose nanofiber composition with excellent dispersibility of cellulose nanofibers, which can easily broaden the range of applications for cellulose. Therefore, it can be used in a wide range of fields, for example, in the field of resin compositions used as materials for molded articles.

Claims

1. The dispersion medium preparation process involves preparing the dispersion medium, A cellulose derivative addition step is performed in which a cellulose derivative is added to the prepared dispersion medium to prepare a cellulose derivative-containing solution, A cellulose nanofiber addition step is performed by adding cellulose nanofibers to the cellulose derivative-containing solution, Includes, The cellulose nanofibers are cellulose nanofibers that have been dried. The cellulose derivative is at least one selected from the group consisting of hydroxyalkylcellulose and alkylcellulose. A method for producing a cellulose nanofiber composition, wherein the dispersion medium is selected from the group consisting of tetrahydrofuran, acetone, an alcohol having 1 to 5 carbon atoms, cyclohexanol, propylene glycol, cyclohexanone, dioxane, cellosolve, butyl cellosolve, glacial acetic acid, formic acid, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, methylene chloride, chloroform, a mixture of benzene and methanol (1:1 by volume), a mixture of toluene and ethanol (3:2 by volume), a mixture of glycerin and water (3:7 by volume), and mixtures of two or more of these.

2. The dispersion medium preparation process involves preparing the dispersion medium, A cellulose nanofiber addition step is performed to prepare a cellulose nanofiber-containing dispersion medium by adding cellulose nanofibers to the prepared dispersion medium, A cellulose derivative addition step is to add a cellulose derivative to the cellulose nanofiber-containing dispersion medium, Includes, The cellulose nanofibers are cellulose nanofibers that have been dried. The cellulose derivative is at least one selected from the group consisting of hydroxyalkylcellulose and alkylcellulose. A method for producing a cellulose nanofiber composition, wherein the dispersion medium is selected from the group consisting of tetrahydrofuran, acetone, an alcohol having 1 to 5 carbon atoms, cyclohexanol, propylene glycol, cyclohexanone, dioxane, cellosolve, butyl cellosolve, glacial acetic acid, formic acid, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, methylene chloride, chloroform, a mixture of benzene and methanol (1:1 by volume), a mixture of toluene and ethanol (3:2 by volume), a mixture of glycerin and water (3:7 by volume), and mixtures of two or more of these.

3. The dispersion medium preparation process involves preparing the dispersion medium, A cellulose component addition step is to add a cellulose derivative and cellulose nanofibers as cellulose components to the prepared dispersion medium, Includes, The cellulose nanofibers are cellulose nanofibers that have been dried. The cellulose derivative is at least one selected from the group consisting of hydroxyalkylcellulose and alkylcellulose. A method for producing a cellulose nanofiber composition, wherein the dispersion medium is selected from the group consisting of tetrahydrofuran, acetone, an alcohol having 1 to 5 carbon atoms, cyclohexanol, propylene glycol, cyclohexanone, dioxane, cellosolve, butyl cellosolve, glacial acetic acid, formic acid, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, methylene chloride, chloroform, a mixture of benzene and methanol (1:1 by volume), a mixture of toluene and ethanol (3:2 by volume), a mixture of glycerin and water (3:7 by volume), and mixtures of two or more of these.

4. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 3, wherein the cellulose derivative is hydroxyalkylcellulose.

5. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 4, wherein the hydroxyalkyl cellulose is hydroxypropyl cellulose.

6. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 5, wherein 5.0 parts by mass or more and 5,000 parts by mass or less of the cellulose derivative are added to 100 parts by mass of the cellulose nanofiber.

7. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 5, wherein 10 to 2000 parts by mass of the cellulose derivative are added to 100 parts by mass of the cellulose nanofiber.

8. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 7, wherein 0.5 parts by mass or more and 120 parts by mass or less of the cellulose derivative are added to 100 parts by mass of the dispersion medium.

9. A method for producing the cellulose nanofiber composition according to any one of claims 1 to 8, wherein the cellulose nanofiber is dispersed.

10. A method for producing a cellulose nanofiber composition according to any one of claims 1 to 9, wherein the drying treatment is freeze-drying.

11. A method for producing a cellulose nanofiber composition according to claim 9, wherein the average value of the transmittance of the dispersion of cellulose nanofibers at a wavelength of 400 nm at a rotation speed of 1000 rpm of the stirring means is 0.30 or less.

12. A method for producing a cellulose nanofiber composition according to claim 9 or 11, wherein the standard deviation of the transmittance of the dispersion of cellulose nanofibers at a wavelength of 400 nm at a rotation speed of 1000 rpm of the stirring means is 0.10 or less.

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