WO2021153590A1

WO2021153590A1 - Method for producing microfibrous cellulose/nanocarbon-containing material, and microfibrous cellulose/nanocarbon-containing material

Info

Publication number: WO2021153590A1
Application number: PCT/JP2021/002766
Authority: WO
Inventors: 裕一野口; 優作今村; 真人齊藤
Original assignee: 王子ホールディングス株式会社
Priority date: 2020-01-28
Filing date: 2021-01-27
Publication date: 2021-08-05

Abstract

The present invention addresses the problem of providing a microfibrous cellulose/nanocarbon-containing material having excellent particle dispersion properties. The present invention relates to a method for producing a microfibrous cellulose/nanocarbon-containing material, the method comprising a step for mixing an ionic substituent-containing cellulose fiber and a nanocarbon precursor, and then performing a refining treatment, wherein bubbling is suppressed in the step for performing the refining treatment. In addition, the present invention also relates to a microfibrous cellulose/nanocarbon-containing material produced by said production method.

Description

Manufacturing method of fine fibrous cellulose / nanocarbon-containing material and fine fibrous cellulose / nanocarbon-containing material

The present invention relates to a method for producing a fine fibrous cellulose / nanocarbon-containing material and a fine fibrous cellulose / nanocarbon-containing material.

Conventionally, cellulose fibers have been widely used in clothing, absorbent articles, paper products, and the like. As the cellulose fibers, in addition to fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Fine fibrous cellulose is attracting attention as a new material, and its uses are wide-ranging. For example, the use of fine fibrous cellulose as a thickener or an additive to various compositions has been studied.

For example,

Patent Documents

1 and 2 disclose a dispersion liquid to which cellulose nanofibers are added for the purpose of enhancing the dispersibility of nanocarbon materials such as carbon nanotubes and graphene. Here, it is studied to suppress the aggregation of the nanocarbon material and improve the dispersion stability in water.

Further, a conductive composition obtained by mixing nanocarbon materials such as carbon nanotubes and graphene with cellulose nanofibers is also known (Patent Documents 3 to 6). Patent Document 3 discloses a conductive composition containing cellulose nanofibers and at least one kind of inorganic powder selected from graphene, graphene oxide and derivatives thereof, and Patent Document 4 Discloses a conductive composite comprising carboxy group-modified cellulose nanofibers and carboxy group-modified carbon nanotubes. Further, Patent Document 5 discloses a conductive non-woven fabric containing fine fibers having an average fiber diameter of 500 nm or less, an average fiber length of 500 μm or less, and a crystallinity of 60% or more, and carbon nanotubes. Further, Patent Document 6 discloses a nanomaterial composition containing a dispersion medium and cellulose nanofibers and carbon nanotubes dispersed in the dispersion medium, and surface hardness when formed into a molded product. Is being considered to improve.

Japanese Unexamined Patent Publication No. 2016-11763639 International Publication No. 2014/115560 International Publication No. 2016/043145 Japanese Unexamined Patent Publication No. 2013-21108 Japanese Unexamined Patent Publication No. 2014-189923 Japanese Unexamined Patent Publication No. 2018-12763

As described above, a mixture of cellulose nanofibers and nanocarbon materials is known, but in the prior art, nanonization of cellulose fibers and nanonization of carbon materials are performed in separate steps, and each of them is performed in separate steps. After being nanonized, mixing was done. In addition, a large amount of energy was required for mixing the cellulose nanofibers and the nanocarbon materials after nano-ization. Therefore, the manufacturing process of the mixture of the cellulose nanofibers and the nanocarbon materials is complicated and expensive, and as a result, the manufacturing cost tends to be high.

Then, while examining the problems of the prior art, the present inventors have poor dispersibility of the fine particles when the fine particles are dispersed in a mixture of the cellulose nanofibers and the nanocarbon material obtained by the conventional manufacturing method. I found that it might be enough.

Therefore, in order to solve the problems of the prior art, the present inventors have proceeded with studies for the purpose of providing a fine fibrous cellulose / nanocarbon-containing material having excellent particle dispersibility.

Specifically, the present invention has the following configuration.

[1] A step of performing a miniaturization treatment on a mixed solution containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent is included.
A method for producing a fine fibrous cellulose / nanocarbon-containing material in which bubbling is suppressed in the step of performing the miniaturization treatment.
[2] The method for producing a fine fibrous cellulose / nanocarbon-containing material according to [1], wherein the content of the solvent in the mixed solution is 99% by mass or less with respect to the total mass of the mixed solution.
[3] The method for producing a fine fibrous cellulose / nanocarbon-containing material according to [1] or [2], wherein in the step of performing the micronization treatment, the miniaturization treatment is performed using a high-pressure homogenizer.
[4] The method for producing a fine fibrous cellulose / nanocarbon-containing material according to any one of [1] to [3], wherein bubbling is suppressed by cooling in the step of performing the micronization treatment.
[5] The method for producing a fine fibrous cellulose / nanocarbon-containing material according to any one of [1] to [4], wherein the ionic substituent is an anionic group.
[6] The method for producing a fine fibrous cellulose / nanocarbon-containing material according to any one of [1] to [5], wherein the ionic substituent is a phospholic acid group or a substituent derived from a phosphoxoic acid group.
[7] It contains fine fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent, and nanocarbon.
Fine fibrous cellulose / nanocarbon-containing material having a thixotropic index value (TI value) of 2 or more calculated under the following condition a;
(Condition a)
The fine fibrous cellulose / nanocarbon-containing material is dispersed in water to obtain a dispersion having a viscosity of 1000 cps measured at 23 ° C. with a B-type viscometer at a rotation speed of 3 rpm; 23 ° C. with a B-type viscometer. The viscosity (η) of the dispersion measured at a rotation speed of 60 rpm is measured, and a value of 1000 / η is defined as a thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing material.
[8] The content of the solvent in the fine fibrous cellulose / nanocarbon-containing material is 99% by mass or less with respect to the total mass of the fine fibrous cellulose / nanocarbon-containing material.
The fine fibrous cellulose / nanocarbon-containing material according to [7], wherein the fine fibrous cellulose and nanocarbon are uniformly dispersed in the fine fibrous cellulose / nanocarbon-containing material.
[9] The fine fibrous cellulose / nanocarbon-containing product according to [7] or [8], wherein the ionic substituent is an anionic group.
[10] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [9], wherein the ionic substituent is a phospholic acid group or a substituent derived from a phosphoxoic acid group.
[11] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [10], wherein the nanocarbon is at least one selected from the group consisting of carbon nanotubes and graphene.
[12] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [11], which is used for paints.
[13] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [11], which is used for a resin composition.
[14] The fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11], which is used for concrete materials.
[15] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [11], which is used for a filamentous or plate-like structure.
[16] The fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11], which is used for electromagnetic wave shielding.
[17] The fine fibrous cellulose / nanocarbon-containing product according to any one of [7] to [11], which is used for an electrochemical device.
[18] A coating material containing the fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11].
[19] A resin composition containing the fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11].
[20] A concrete material containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
[21] A filamentous or plate-like structure containing the fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11].
[22] An electromagnetic wave shield containing the fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11].
[23] An electrochemical device containing the fine fibrous cellulose / nanocarbon-containing material according to any one of [7] to [11].

According to the production method of the present invention, a fine fibrous cellulose / nanocarbon-containing material having excellent particle dispersibility can be obtained.

FIG. 1 is a schematic view illustrating an example of the configuration of a miniaturization processing device. FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to the fine fibrous cellulose dispersion having a phosphorus oxo acid group and the pH. FIG. 3 is a graph showing the relationship between the amount of NaOH added dropwise to the fine fibrous cellulose dispersion having a carboxy group and the pH.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments.

(Manufacturing method of fine fibrous cellulose / nanocarbon-containing material)
The present embodiment is a method for producing a fine fibrous cellulose / nanocarbon-containing product containing fine fibrous cellulose and nanocarbon. The method for producing a fine fibrous cellulose / nanocarbon-containing material of the present embodiment includes a step of performing a micronization treatment on a mixed solution containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent. Then, bubbling is suppressed in the step of performing the miniaturization process. In the present specification, the fine fibrous cellulose refers to fibrous cellulose having a fiber width of 1000 nm or less. Further, in the present specification, nanocarbon may be referred to as a nanocarbon material or carbon nanoparticles. In the present specification, the nanocarbon precursor is a carbon material before miniaturization (nano-miniaturization).

In the method for producing a fine fibrous cellulose / nanocarbon-containing material of the present embodiment, a mixed solution obtained by mixing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent is subjected to a micronization treatment. In the step of performing this miniaturization treatment, bubbling is suppressed. By going through such a manufacturing process, the fine fibrous cellulose / nanocarbon-containing material produced by the manufacturing method of the present embodiment exhibits excellent particle dispersibility. Regarding the particle dispersibility in the fine fibrous cellulose / nanocarbon-containing material, for example, the fine fibrous cellulose / nanocarbon-containing material is used as a dispersion liquid having a total dry solid content concentration of 0.2% by mass, and glass beads are prepared therein. It can be evaluated by the presence or absence of sedimentation of the glass beads when the above is added. When the settling of the glass beads is slight or no settling of the glass beads is observed, it can be determined that the dispersibility of the fine fibrous cellulose and the nanocarbon material is good.

Further, since the fine fibrous cellulose / nanocarbon-containing material of the present embodiment is produced by the above-mentioned production method, it is exhibited without impairing the characteristics of each material. The characteristics of each material in the fine fibrous cellulose / nanocarbon-containing material can be evaluated by, for example, calculating the TI value of the fine fibrous cellulose / nanocarbon-containing material.

The content of the solvent in the mixed solution to be subjected to the miniaturization treatment step is preferably 99% by mass or less, more preferably 98% by mass or less, based on the total mass of the mixed solution. The content of the solvent in the mixed solution to be subjected to the miniaturization treatment step may be 95% by mass or less, or 90% by mass or less, based on the total mass of the mixed solution. In this way, by lowering the solvent content of the mixed solution used in the micronization treatment step and increasing the solid content content, fine fibrous cellulose in which fine fibrous cellulose and nanocarbon are more uniformly dispersed. A nanocarbon-containing material is obtained. As a result, the fine fibrous cellulose / nanocarbon-containing material produced by the production method of the present embodiment can exhibit excellent particle dispersibility. Further, by lowering the solvent content of the mixed solution used in the miniaturization treatment step and increasing the solid content content, the production efficiency of the fine fibrous cellulose / nanocarbon-containing product can be increased. The lower limit of the solvent content in the mixed solution to be subjected to the miniaturization treatment step is not particularly limited, but is, for example, 70% by mass or more with respect to the total mass of the mixed solution.

In the production method of the present embodiment, the step of performing the miniaturization treatment (hereinafter, also referred to as the miniaturization treatment step) is performed after mixing the cellulose fiber having an ionic substituent, the nanocarbon precursor, and the solvent. It is said. That is, the miniaturization treatment is performed on a mixed solution (dispersion solution) containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent. The miniaturization treatment in the present specification is synonymous with the nano-processing.

Conventionally, in the method for producing a fine fibrous cellulose / nanocarbon-containing material, first, the cellulose fibers are miniaturized (nano-sized) and the carbon material is miniaturized (nano-sized) in separate steps, and then each step is performed. The fine fibrous cellulose obtained in 1 and nanocarbon were mixed. That is, all the materials were mixed after being nano-sized. Here, when each material is nano-sized, the dispersion stability may not be maintained until the nano-sized materials are mixed, and there is a problem in the uniform dispersibility of each material. In addition, high energy is required when mixing each nano-sized material, and further, very high energy is required in the process of obtaining fine fibrous cellulose and nanocarbon, respectively, so that fine fibrous material is required. The energy required to obtain the cellulose / nanocarbon-containing material was enormous.

However, in the present embodiment, since the micronization treatment step is performed after mixing the cellulose fiber having an ionic substituent and the nanocarbon precursor, the number of miniaturization treatment steps requiring high energy is significantly increased. It is possible to reduce the amount. As a result, the production efficiency of the fine fibrous cellulose / nanocarbon-containing material can be significantly improved. Further, in the present embodiment, since the micronization treatment step is performed after mixing the cellulose fiber having an ionic substituent and the nanocarbon precursor, the dispersibility of each nano-sized material is high, and the fine fiber. The cellulose / nanocarbon-containing material exhibits excellent particle dispersibility. Further, by omitting the step of mixing the nano-sized materials, damage to each nano-sized material can be suppressed, and as a result, the characteristics of each material can be fully exhibited.

Before the miniaturization treatment step, a step of mixing the cellulose fiber having an ionic substituent, the nanocarbon precursor, and the solvent is provided. Here, a nanocarbon precursor or a dispersion of the nanocarbon precursor is added to a mixed solution (dispersion solution) containing a cellulose fiber having an ionic substituent and a solvent, and the mixture is mixed. The mixing ratio (mass ratio) of the cellulose fiber having an ionic substituent and the nanocarbon precursor in the mixing step is preferably 1:99 to 99: 1, and is preferably 5:95 to 95: 5. Is more preferable, and 10:90 to 90:10 is even more preferable.

In the miniaturization processing step, for example, a miniaturization processing apparatus can be used. The micronization processing device is not particularly limited, but for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, and a twin shaft. A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, or a beater can be used. Among the above-mentioned miniaturization processing devices, it is preferable to use at least one selected from the group consisting of a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by crushed media and less likely to cause contamination. It is more preferable to use it. Above all, it is preferable to use a high-pressure homogenizer (Beryu-Mini) manufactured by Bitsubu Co., Ltd.

In the miniaturization treatment step, the cellulose fiber having an ionic substituent and the nanocarbon precursor are diluted with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from water and an organic solvent such as a polar organic solvent can be used. The polar organic solvent is not particularly limited, but for example, alcohols, polyhydric alcohols, ketones, ethers, esters, aprotic polar solvents and the like are preferable. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, glycerin and the like. Examples of the ketones include acetone, methyl ethyl ketone (MEK) and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monon-butyl ether, propylene glycol monomethyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate and the like. Examples of the aprotonic polar solvent include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.

The solid content concentration (total concentration of cellulose fibers and nanocarbon precursors) during the miniaturization treatment can be set as appropriate. Further, in the dispersion liquid during the miniaturization treatment, various solids used for obtaining ionic substituent-introduced cellulose fibers such as urea having hydrogen bonding properties and various solids contained in the carbon precursor are contained in the dispersion. It may be included.

In the miniaturization treatment step of the present embodiment, bubbling is suppressed, and by suppressing the bubbling, the miniaturization (nano-sized) of the cellulose fiber and the miniaturization (nano-sized) of the carbon material are simultaneously performed and energy efficient. Will be done. Further, by suppressing bubbling in the miniaturization treatment step, it is possible to more effectively suppress damage to each nano-sized material, and as a result, the dispersibility of each material is high and the particle dispersibility is improved. A fine fibrous cellulose / nanocarbon-containing material that is excellent and can fully exhibit the characteristics of each material can be obtained.

In the present specification, bubbling means, for example, residual in air dissolved in a solvent or in a solvent due to the existence of a local pressure difference or velocity difference in a place where a shearing force acts in a miniaturization processing step. This is a phenomenon in which the air is generated as bubbles. The occurrence of bubbling may require more energy in the micronization process, may result in inadequate or non-uniform miniaturization of the cellulose fibers and nanocarbon precursors. This is because the solvent does not touch the cellulose fibers or nanocarbon precursors where bubbling occurs, and "wetting", which is essential for miniaturization (particularly defibration / peeling), does not occur. Is considered to be. Further, since the bubbling portion shows compression resistance against pushing of a high-pressure pump or the like, it may lead to damage to the machine. In addition, each material may be unintentionally oxidized due to air bubbles generated by bubbling. In the present embodiment, by positively suppressing bubbling in the miniaturization treatment step, the energy required in the miniaturization treatment step can be suppressed, and further, the cellulose fibers and the nanocarbon precursor can be miniaturized. It can be performed more efficiently and with high accuracy. Further, by suppressing bubbling, it is possible to suppress the oxidation of fine fibrous cellulose and nanocarbon.

In the process of performing the miniaturization process, it is preferable to suppress bubbling by cooling. That is, the bubbling suppression mechanism is preferably a cooling mechanism, and the miniaturization processing device is preferably provided with a cooling device or a cooling mechanism. That is, the production method of the present embodiment includes a step of performing a miniaturization treatment on a mixed solution containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent, and in the step of performing the miniaturization treatment, It is preferable that cooling is performed. Further, the cooling may be performed after the pressure is released in the micronization treatment, but the back pressure is applied, that is, the cellulose fibers having ionic substituents and the nanocarbon precursor are miniaturized. It is preferably done in the middle.

Examples of the cooling mechanism include a shell or an outer tube through which a heat transfer medium circulates on the outer periphery of the miniaturization processing device. In this case, the dispersion liquid of the cellulose fiber and the nanocarbon precursor is circulated on the inner peripheral side (inner tube) of the miniaturization treatment device, and when the miniaturization treatment is performed, the heat transfer medium is applied to the outer shell or the outer tube. The dispersion can be cooled by circulating it. The inner tube through which the dispersion liquid of the cellulose fiber and the nanocarbon precursor is circulated is preferably a heat transfer tube. As a result, the dispersion liquid can be efficiently cooled.

It is preferable that the bubbling suppression mechanism is provided on the downstream side of the jet flow generating portion provided in the miniaturization processing device. It is preferable that the jet flow generating portion is provided with a jet flow generating mechanism, and the jet flow generating portion is provided with, for example, a diamond nozzle or a slit as a jet flow generating mechanism so that the flow path diameter is changed in the flow direction. A mechanism for rapidly or gradually thinning may be provided. As shown in FIG. 1, the miniaturization processing device 100 includes a jet flow generating unit 10 and a bubbling suppressing unit 20 provided on the downstream side of the jet flow generating unit 10. The bubbling suppressing unit 20 is preferably provided with a coolable pipe (cloak), and such a pipe (cloak) is arranged so as to cover an inner pipe through which the dispersion liquid flows. Then, by introducing, for example, cooling water or the like into the pipe (cloak), the dispersion liquid flowing in the inner pipe can be cooled.

The length L (L in FIG. 1) of the coolable pipe provided in the bubbling suppressing portion 20 is preferably 1 mm or more and 1000 mm or less, more preferably 10 mm or more and 750 mm or less, and 100 mm or more and 500 mm or less. Is even more preferable. By setting the length (L) of the pipe that can be cooled within the above range, it becomes easy to sufficiently cool the dispersion liquid flowing in the inner pipe, and the occurrence of bubbling can be suppressed more effectively.

Further, in the miniaturization processing apparatus 100, it is preferable that a predetermined distance is provided between the upstream end of the bubbling suppressing unit 20 and the downstream end of the jet flow generating unit 10. As shown in FIG. 1, the jet flow generation unit 10 and the bubbling suppression unit 20 are not connected, and a predetermined distance (D) is between the downstream end of the jet flow generation unit 10 and the upstream end of the bubbling suppression unit 20. ) Is preferably provided. The predetermined distance (D) is preferably 1 mm or more and 500 mm or less, more preferably 10 mm or more and 300 mm or less, and further preferably 20 mm or more and 200 mm or less. By providing the predetermined distance (D), the occurrence of bubbling can be suppressed more effectively.

When the cooling water is introduced into the pipe (cloak) of the bubbling suppression unit 20, the temperature of the cooling water is preferably 40 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower. preferable. The flow rate of the cooling water is preferably 1 L / min or more, more preferably 5 L / min or more, and further preferably 10 L / min or more. The temperature of the dispersion liquid after cooling after passing through the bubbling suppressing unit 20 is preferably 60 ° C. or lower, more preferably 40 ° C. or lower, and further preferably 20 ° C. or lower.

In the bubbling suppression mechanism, it is preferable that a pressure (back pressure) of at least 5% or more (0.05P or more) is applied to the pressure (P) applied to the dispersion liquid at the jet flow generating portion, and 10% or more (0. It is more preferable that a pressure of 1 P or more is applied, and it is further preferable that a pressure of 20% or more (0.2 P or more) is applied. Further, since bubbling is more likely to occur when the treatment is performed at an ultra-high pressure, controlling the pressure of the jet flow generating portion from low pressure to high pressure is also effective in suppressing bubbling. The processing pressure of the jet flow generating portion is preferably 1 MPa or more and 200 MPa or less, more preferably 10 MPa or more and 170 MPa or less, and further preferably 20 MPa or more and 150 MPa or less.

As the bubbling suppression mechanism, it is preferable to refer to the mechanism described in Japanese Patent No. 5791142 and appropriately adopt it. Further, as the miniaturization processing device, the emulsification dispersion device, the multi-stage pressure control device, and the like described in Japanese Patent No. 5791142 can be adopted.

As described above, by simultaneously refining the cellulose fiber and the carbon material in the micronization treatment step in which bubbling is suppressed, a fine fibrous cellulose / nanocarbon dispersion liquid containing fine fibrous cellulose and nanocarbon can be obtained. .. In the present specification, the fine fibrous cellulose / nanocarbon dispersion obtained through the micronization treatment step is also included in the fine fibrous cellulose / nanocarbon-containing material. The fine fibrous cellulose / nanocarbon-containing material also includes a concentrate or a solid product obtained by concentrating the fine fibrous cellulose / nanocarbon dispersion.

(Cellulose fiber)
The cellulose fiber used in the above-mentioned miniaturization treatment step is a fiber raw material before the miniaturization treatment. Cellulose fibers are coarse fibers, and the fiber width is larger than 1000 nm. The average fiber width of the cellulose fibers is larger than 1000 nm.

Cellulose fibers having an ionic substituent are obtained from a fiber raw material containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, but is, for example, broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), and unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton pulp such as cotton linter and cotton lint, and non-wood pulp such as hemp, straw and bagasse. The deinking pulp is not particularly limited, and examples thereof include deinking pulp made from recycled paper. As the pulp of the present embodiment, one of the above types may be used alone, or two or more types may be mixed and used. Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of availability. Further, among wood pulps, it is possible to obtain long-fiber fine fibrous cellulose having a large cellulose ratio and a high yield of fine fibrous cellulose during the micronization treatment, and having a small decomposition of cellulose in the pulp and a large axial ratio. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable.

As the fiber raw material containing cellulose, for example, cellulose contained in ascidians and bacterial cellulose produced by acetic acid bacteria can be used. Further, instead of the fiber raw material containing cellulose, a fiber formed by a linear nitrogen-containing polysaccharide polymer such as chitin or chitosan can also be used.

Cellulose fiber has an ionic substituent. The ionic substituent can include, for example, either one or both of an anionic group and a cationic group. In this embodiment, it is particularly preferable to have an anionic group as the ionic substituent.

Examples of the anionic group include a phosphoric acid group or a substituent derived from a phosphoric acid group (sometimes simply referred to as a phosphoric acid group), a carboxy group or a substituent derived from a carboxy group (sometimes simply referred to as a carboxy group), and the like. Examples thereof include a sulfone group or a substituent derived from the sulfone group (sometimes referred to simply as a sulfon group), a zantate group, a phosphone group, a phosphine group, a carboxyalkyl group (including a carboxymethyl group) and the like. When a sulfone group or a substituent derived from a sulfone group is introduced via an ester bond, the substituent is referred to as a sulfur oxo acid group or a substituent derived from a sulfur oxo acid group (simply referred to as a sulfur oxo acid group). There is also). Among them, the anionic group is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a carboxymethyl group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. It is preferably a species, and is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. Is more preferable, and a phosphorusoxo acid group is particularly preferable. Examples of the cationic group as the ionic substituent include an ammonium group, a phosphonium group, a sulfonium group and the like. Of these, the cationic group is preferably an ammonium group.

The phosphate group or the substituent derived from the phosphorusoxo acid group is, for example, a substituent represented by the following formula (1). A plurality of types of substituents represented by the following formula (1) may be introduced into each cellulose fiber. In this case, the substituents represented by the following formula (1) to be introduced may be the same or different.

In the formula (1), a, b and n are natural numbers, and m is an arbitrary number (where a = b × m). At least one of the n α and α'is O ⁻ and the rest are R or OR. It is also possible that all of each α and α'are O ^−. The n αs may all be the same or different. β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance.

R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, and an unsaturated-branched chain hydrocarbon, respectively. A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. Further, in the formula (1), n is preferably 1.

Examples of the saturated-linear hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like, but are not particularly limited. Examples of the saturated-branched chain hydrocarbon group include an i-propyl group and a t-butyl group, but are not particularly limited. Examples of the saturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentyl group, a cyclohexyl group and the like. Examples of the unsaturated-linear hydrocarbon group include a vinyl group, an allyl group and the like, but are not particularly limited. Examples of the unsaturated-branched chain hydrocarbon group include an i-propenyl group and a 3-butenyl group, but the group is not particularly limited. Examples of the unsaturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentenyl group, a cyclohexenyl group and the like. Examples of the aromatic group include a phenyl group and a naphthyl group, but are not particularly limited.

As the derivative groups in R, to the main chain or side chain of the various hydrocarbon group, a carboxy group, a carboxylate group (-COO ^-), hydroxy group, selected from the functional groups such as an amino group and an ammonium group Examples thereof include functional groups in which at least one type is added or substituted, but the functional group is not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorus oxo acid group can be set to an appropriate range, permeation into the fiber raw material is facilitated, and the yield of cellulose fiber is increased. You can also. When a plurality of Rs are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the cellulose fiber, the plurality of Rs present are the same. May be different.

β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include organic onium ions. Examples of the organic onium ion include an organic ammonium ion and an organic phosphonium ion. Examples of the organic ammonium ion include an aliphatic ammonium ion and an aromatic ammonium ion, and examples of the organic phosphonium ion include an aliphatic phosphonium ion and an aromatic phosphonium ion. Examples of monovalent or higher cations composed of inorganic substances include alkali metal ions such as sodium, potassium, and lithium, divalent metal ions such as calcium and magnesium, hydrogen ions, and ammonium ions. When a ^{plurality of β b +} are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the cellulose fiber, the plurality of β ^{b +} present are the same. It may be different. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing ^{β b + is heated and is easily industrially used, but is not particularly limited.} ..

Specific examples of the phosphorous acid group or the substituent derived from the phosphorous acid group include a phosphoric acid group (-PO ₃ H ₂ ), a salt of a phosphorous acid group, and a phosphorous acid group (phosphonic acid group) (-PO). ₂ H _2), and salts of phosphorous acid (phosphonic acid group). Further, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a group in which a phosphoric acid group is condensed (for example, a pyrophosphate group), a group in which a phosphonic acid is condensed (for example, a polyphosphonic acid group), and a phosphoric acid ester group (for example, a phosphoric acid ester group). For example, it may be a monomethylphosphoric acid group, a polyoxyethylene alkylphosphoric acid group), an alkylphosphonic acid group (for example, a methylphosphonic acid group) or the like.

Further, the sulfone group (sulfo group or substituent derived from the sulfone group) is, for example, a substituent represented by the following formula (2). A plurality of types of substituents represented by the following formula (2) may be introduced into each cellulose fiber. In this case, the substituents represented by the following formula (2) to be introduced may be the same or different.

In the above structural formula, b and n are natural numbers, p is 0 or 1, and m is an arbitrary number (where 1 = b × m). When n is 2 or more, a plurality of ps may be the same number or different numbers. In the above structural formula, β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include organic onium ions. Examples of the organic onium ion include an organic ammonium ion and an organic phosphonium ion. Examples of the organic ammonium ion include an aliphatic ammonium ion and an aromatic ammonium ion, and examples of the organic phosphonium ion include an aliphatic phosphonium ion and an aromatic phosphonium ion. Examples of monovalent or higher cations composed of inorganic substances include alkali metal ions such as sodium, potassium, and lithium, divalent metal ions such as calcium and magnesium, hydrogen ions, and ammonium ions. When a plurality of types of substituents represented by the above formula (2) are introduced into the cellulose fiber, the plurality of β ^{b +} existing may be the same or different. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing ^{β b + is heated and is easily industrially used, but is not particularly limited.} ..

The amount of the ionic substituent introduced into the cellulose fiber is, for example, preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g or more, and 0.20 mmol / g per 1 g (mass) of the cellulose fiber. The above is more preferable, 0.40 mmol / g or more is more preferable, and 0.60 mmol / g or more is particularly preferable. The amount of the ionic substituent introduced into the cellulose fiber is, for example, 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and 3.00 mmol / g per 1 g (mass) of the cellulose fiber. It is more preferably / g or less. Here, the denominator in the unit mmol / g indicates the mass of the cellulose fiber when the counter ion of the ionic substituent is a hydrogen ion (H ^+). By setting the amount of the ionic substituent introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the cellulose fiber.

The amount of the ionic substituent introduced into the cellulose fiber can be measured by, for example, the neutralization titration method after the cellulose fiber is subjected to the micronization treatment. In the measurement by the neutralization titration method, the introduction amount is measured by determining the change in pH while adding an alkali such as an aqueous solution of sodium hydroxide to the obtained slurry containing the cellulose fibers.

FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to the fine fibrous cellulose dispersion having a phosphorus oxo acid group and the pH. The amount of phosphorus oxo acid group introduced into the cellulose fiber is measured as follows, for example.
First, ion-exchanged water is added to the target cellulose fibers to prepare a slurry having a solid content concentration of 0.2% by mass. This slurry is treated four times at a pressure of 200 MPa with a wet atomizing device (Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion (slurry) containing fine fibrous cellulose. Then, the fine fibrous cellulose dispersion is treated with a strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 2 is obtained. The titration curve shown in the upper part of FIG. 2 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 2 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, two points are confirmed in which the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point became equal to the amount of first dissociated acid of the fine fibrous cellulose contained in the slurry used for titration, and was required from the first end point to the second end point. The amount of alkali is equal to the amount of second dissociating acid of the fine fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the start to the second end point of titration is contained in the slurry used for titration. Equal to the total dissociated acid content of the fibrous cellulose. Then, the value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol / g). The amount of phosphorus oxo acid group introduced (or the amount of phosphorus oxo acid group) simply means the amount of the first dissociated acid.
In FIG. 2, the region from the start of titration to the first end point is referred to as a first region, and the region from the first end point to the second end point is referred to as a second region. For example, when the phosphoric acid group is a phosphoric acid group and this phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently It decreases, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so that the amount of alkali required for the second region is reduced or the amount of alkali required for the second region is reduced. May be zero. In this case, there is only one point on the titration curve where the pH increment is maximized.

Since the denominator of the above-mentioned phosphorus oxo acid group introduction amount (mmol / g) indicates the mass of the acid-type fine fibrous cellulose, the phosphorus oxo acid group amount (hereinafter, phosphorus oxo acid) possessed by the acid-type fine fibrous cellulose It is called the base amount (acid type)). On the other hand, when the counterion of the phosphorus oxo acid group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of the fine fibrous cellulose when the cation C is the counterion. By doing so, the amount of phosphorus oxo acid groups (hereinafter, the amount of phosphorus oxo acid groups (C type)) possessed by the fine fibrous cellulose in which the cation C is a counterion can be obtained.
That is, it is calculated by the following formula.
Phosphoric acid group amount (C type) = Phosphoric acid group amount (acid type) / {1+ (W-1) x A / 1000}
A [mmol / g]: Total anion amount derived from phosphoric acid group of fine fibrous cellulose (total dissociated acid amount of phosphoric acid group)
W: Formula amount per valence of cation C (for example, Na is 23, Al is 9)

FIG. 3 is a graph showing the relationship between the amount of NaOH added dropwise to the fine fibrous cellulose dispersion having a carboxy group as an ionic substituent and the pH. The amount of the carboxy group introduced into the cellulose fiber is measured, for example, as follows.
First, ion-exchanged water is added to the target cellulose fibers to prepare a slurry having a solid content concentration of 0.2% by mass. This slurry is treated four times at a pressure of 200 MPa with a wet atomizing device (Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion (slurry) containing fine fibrous cellulose. Then, the fine fibrous cellulose dispersion is treated with a strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 3 is obtained. The titration curve shown in the upper part of FIG. 3 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 3 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, in the curve plotting the measured pH with respect to the amount of alkali added, one point was confirmed where the increment (differential value of pH with respect to the amount of alkali dropped) became maximum, and this maximum point was the first. Called one end point. Here, the region from the start of titration to the first end point in FIG. 3 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the dispersion used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the dispersion containing the fine fibrous cellulose to be titrated, so that the amount of carboxy group introduced (the amount of carboxy group introduced (mmol) mmol / g) is calculated.

Since the denominator of the above-mentioned carboxy group introduction amount (mmol / g) is the mass of the acid-type fine fibrous cellulose, the carboxy group amount of the acid-type fine fibrous cellulose (hereinafter, the carboxy group amount (hereinafter, carboxy group amount) It is called (acid type)). On the other hand, when the counterion of the carboxy group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted into the mass of fine fibrous cellulose when the cation C is a counterion. This makes it possible to determine the amount of carboxy group (hereinafter, carboxy group amount (C type)) possessed by the fine fibrous cellulose in which the cation C is a counter ion. That is, it is calculated by the following formula.
Carboxylic acid group amount (C type) = Carboxylic acid group amount (acid type) / {1+ (W-1) x (carboxyl group amount (acid type)) / 1000}
W: Formula amount per valence of cation C (for example, Na is 23, Al is 9)

In the measurement of the amount of ionic substituents by the titration method, if the amount of one drop of sodium hydroxide aqueous solution is too large, or if the titration interval is too short, the amount of ionic substituents will be lower than it should be. It may not be obtained. As an appropriate dropping amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of a 0.1 N sodium hydroxide aqueous solution every 5 to 30 seconds. Further, in order to eliminate the influence of carbon dioxide dissolved in the fine fibrous cellulose dispersion, it is desirable to measure, for example, from 15 minutes before the start of titration to the end of titration while blowing an inert gas such as nitrogen gas into the slurry. ..

The amount of sulfone groups introduced into the cellulose fibers can be calculated by freeze-drying the slurry containing the cellulose fibers and then measuring the amount of sulfur in the crushed sample. Specifically, a slurry containing cellulose fibers is freeze-dried, and the crushed sample is decomposed by heating under pressure using nitric acid in a closed container, diluted appropriately, and the amount of sulfur is measured by ICP-OES. The value calculated by dividing by the absolute dry mass of the fibrous cellulose tested is taken as the amount of sulfone groups (unit: mmol / g) of the fibrous cellulose fiber.

In order to obtain the above-mentioned ionic substituent-introduced cellulose fiber, the above-mentioned ionic substituent introduction step, washing step, and alkali treatment step (neutralization) in which the ionic substituent is introduced into the fiber raw material containing cellulose. Step), it is preferable to have a defibration treatment step in this order, and an acid treatment step may be provided instead of the washing step or in addition to the washing step. The ionic substituent introduction step includes a phosphorus oxo acid group introduction step, a carboxy group introduction step, a sulfur oxo acid group introduction step, a zantate group introduction step, a phosphone group or phosphine group introduction step, a sulfone group introduction step, and a cation group introduction step. Is exemplified. Each will be described below.

<Linoxo acid group introduction process>
When obtaining a cellulose fiber having an ionic substituent, it is preferable to provide an ionic substituent introduction step before the micronization treatment step. Examples of the ionic substituent introduction step include a phosphorus oxo acid group introduction step. In the phosphorus oxo acid group introduction step, at least one compound (hereinafter, also referred to as “compound A”) selected from compounds capable of introducing a phosphorus oxo acid group by reacting with a hydroxyl group of a fiber raw material containing cellulose is introduced into cellulose. It is a step of acting on a fiber raw material containing. By this step, a cellulose fiber having a phosphorus oxo acid group can be obtained.

In the phosphorus oxo acid group introduction step according to the present embodiment, the reaction between the fiber raw material containing cellulose and Compound A is carried out in the presence of at least one selected from urea and its derivatives (hereinafter, also referred to as “Compound B”). You may. On the other hand, the reaction of the fiber raw material containing cellulose with the compound A may be carried out in the absence of the compound B.

As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B, there is a method of mixing the compound A and the compound B with the fiber raw material in a dry state, a wet state or a slurry state. Of these, since the reaction uniformity is high, it is preferable to use a fiber raw material in a dry state or a wet state, and it is particularly preferable to use a fiber raw material in a dry state. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. Examples of the compound A and the compound B include a method of adding the compound A and the compound B to the fiber raw material in the form of a powder or a solution dissolved in a solvent, or in a state of being heated to a melting point or higher and melted. Of these, since the reaction uniformity is high, it is preferable to add the solution in the form of a solution dissolved in a solvent, particularly in the state of an aqueous solution. Further, the compound A and the compound B may be added to the fiber raw material at the same time, may be added separately, or may be added as a mixture. The method for adding the compound A and the compound B is not particularly limited, but when the compound A and the compound B are in the form of a solution, the fiber raw material may be immersed in the solution to absorb the liquid and then taken out, or the fiber raw material may be taken out. The solution may be dropped into the water. Further, the required amounts of compound A and compound B may be added to the fiber raw material, or after the excess amounts of compound A and compound B are added to the fiber raw material, respectively, the surplus compound A and compound B are added by pressing or filtering. It may be removed.

The compound A used in this embodiment may be a compound having a phosphorus atom and capable of forming an ester bond with cellulose, and may be phosphoric acid or a salt thereof, phosphoric acid or a salt thereof, dehydration-condensed phosphoric acid or a salt thereof. Examples thereof include salts and anhydrous phosphoric acid (diphosphorus pentoxide), but the present invention is not particularly limited. As the phosphoric acid, those having various puritys can be used, and for example, 100% phosphoric acid (normal phosphoric acid) or 85% phosphoric acid can be used. Examples of phosphorous acid include 99% phosphorous acid (phosphonic acid). The dehydration-condensed phosphoric acid is one in which two or more molecules of phosphoric acid are condensed by a dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Phosphates, phosphorous acids, dehydration-condensed phosphates include phosphoric acid, phosphorous acid or dehydration-condensed phosphoric acid lithium salts, sodium salts, potassium salts, ammonium salts, etc. It can be a sum. Of these, from the viewpoints of high introduction efficiency of phosphoric acid group, easy improvement of defibration efficiency in the defibration step described later, low cost, and easy industrial application, sodium phosphate and sodium phosphate Salt, potassium salt of phosphoric acid, ammonium or phosphite of phosphoric acid, sodium salt of phosphite, potassium salt of phosphite, ammonium salt of phosphite are preferred, phosphoric acid, sodium dihydrogen phosphate, Disodium hydrogen phosphate, ammonium dihydrogen phosphate, or phosphoric acid and sodium phosphite are more preferred.

The amount of compound A added to the fiber raw material is not particularly limited, but for example, when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material (absolute dry mass) is 0.5% by mass or more. It is preferably 100% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and further preferably 2% by mass or more and 30% by mass or less. By setting the amount of phosphorus atoms added to the fiber raw material within the above range, the yield of fine fibrous cellulose can be further improved. On the other hand, by setting the addition amount of the phosphorus atom to the fiber raw material to be equal to or less than the above upper limit value, the effect of improving the yield and the cost can be balanced.

Compound B used in this embodiment is at least one selected from urea and its derivatives as described above. Examples of compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like. From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. Further, from the viewpoint of further improving the uniformity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.

The amount of compound B added to the fiber raw material (absolute dry mass) is not particularly limited, but is preferably 1% by mass or more and 500% by mass or less, and more preferably 10% by mass or more and 400% by mass or less. It is more preferably 100% by mass or more and 350% by mass or less.

In the reaction between the fiber raw material containing cellulose and compound A, for example, amides or amines may be contained in the reaction system in addition to compound B. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine in particular is known to act as a good reaction catalyst.

In the phosphorus oxo acid group introduction step, it is preferable to add or mix compound A or the like to the fiber raw material and then heat-treat the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature at which a phosphorus oxo acid group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is, for example, preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. In addition, equipment having various heat media can be used for the heat treatment, for example, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, a fluidized layer drying device, and a band. A mold drying device, a filtration drying device, a vibration flow drying device, an air flow drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device can be used.

In the heat treatment according to the present embodiment, for example, compound A is added to a thin sheet-shaped fiber raw material by a method such as impregnation and then heated, or the fiber raw material and compound A are heated while kneading or stirring with a kneader or the like. Can be adopted. This makes it possible to suppress uneven concentration of the compound A in the fiber raw material and more uniformly introduce the phosphorus oxo acid group onto the surface of the cellulose fiber contained in the fiber raw material. This is because when the water molecules move to the surface of the fiber raw material due to drying, the dissolved compound A is attracted to the water molecules by the surface tension and also moves to the surface of the fiber raw material (that is, the concentration unevenness of the compound A is caused. It is considered that this is due to the fact that it can be suppressed.

Further, the heating device used for the heat treatment always keeps the water content retained by the slurry and the water content generated by the dehydration condensation (phosphoric acid esterification) reaction between the compound A and the hydroxyl group contained in the cellulose or the like in the fiber raw material. It is preferable that the device can be discharged to the outside of the device system. Examples of such a heating device include a ventilation type oven and the like. By constantly discharging the water in the apparatus system, it is possible to suppress the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, and also to suppress the acid hydrolysis of the sugar chain in the fiber. can. Therefore, it is possible to obtain fine fibrous cellulose having a high axial ratio.

The heat treatment time is preferably 1 second or more and 300 minutes or less, more preferably 1 second or more and 1000 seconds or less, and 10 seconds or more and 800 seconds or less after the water is substantially removed from the fiber raw material. Is more preferable. In the present embodiment, the amount of the phosphorus oxo acid group introduced can be within a preferable range by setting the heating temperature and the heating time within an appropriate range.

The phosphorus oxo acid group introduction step may be performed at least once, but may be repeated twice or more. By performing the phosphorus oxo acid group introduction step two or more times, many phosphorus oxo acid groups can be introduced into the fiber raw material.

The amount of the phosphorus oxo acid group introduced into the fiber raw material is, for example, preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g or more, and 0.20 mmol / g or more per 1 g (mass) of the cellulose fiber. It is even more preferably 0.40 mmol / g or more, even more preferably 0.50 mmol / g or more, and even more preferably 0.60 mmol / g or more. It is particularly preferably 00 mmol / g or more. The amount of the phosphorus oxo acid group introduced into the fiber raw material is, for example, 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and 3.00 mmol / g / g per 1 g (mass) of the cellulose fiber. It is more preferably g or less. By setting the amount of the phosphorus oxo acid group introduced within the above range, it is possible to facilitate the miniaturization of the cellulose fibers in the miniaturization treatment step and enhance the stability of the fine fibrous cellulose.

<Carboxylic acid group introduction process>
The ionic substituent introduction step may include a carboxy group introduction step. The carboxy group introduction step has an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a group derived from carboxylic acid or a derivative thereof, or a group derived from carboxylic acid with respect to the fiber raw material containing cellulose. This is done by treating with an acid anhydride of the compound or a derivative thereof.

The compound having a group derived from a carboxylic acid is not particularly limited, but for example, a dicarboxylic acid compound such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, itaconic acid, citric acid, aconitic acid and the like. Examples include tricarboxylic acid compounds. The derivative of the compound having a group derived from a carboxylic acid is not particularly limited, and examples thereof include an imide of an acid anhydride of a compound having a carboxy group and a derivative of an acid anhydride of a compound having a carboxy group. The imide of the acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinateimide, and phthalateimide.

The acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a dicarboxylic acid compound such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride and the like. Acid anhydride can be mentioned. The derivative of the acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a compound having a carboxy group such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride and the like. Examples thereof include those in which at least a part of the hydrogen atom of the acid anhydride is substituted with a substituent such as an alkyl group or a phenyl group.

When the TEMPO oxidation treatment is performed in the carboxy group introduction step, it is preferable to perform the treatment under conditions of pH 6 or more and 8 or less, for example. Such a treatment is also referred to as a neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) as a catalyst, and the like. This can be done by adding a nitroxy radical and sodium hypochlorite as a sacrificial reagent. Further, by coexisting with sodium chlorite, the aldehyde generated in the oxidation process can be efficiently oxidized to the carboxy group. Further, the TEMPO oxidation treatment may be carried out under the condition that the pH is 10 or more and 11 or less. Such a treatment is also referred to as an alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be carried out, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a co-catalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. ..

The amount of the carboxy group introduced into the cellulose fiber varies depending on the type of the substituent, but when the carboxy group is introduced by TEMPO oxidation, for example, it is preferably 0.05 mmol / g or more per 1 g (mass) of the cellulose fiber, and is 0. .10 mmol / g or more is more preferable, 0.20 mmol / g or more is further preferable, 0.40 mmol / g or more is further preferable, and 0.60 mmol / g or more is particularly preferable. .. The amount of the carboxy group introduced into the cellulose fiber is preferably 3.65 mmol / g or less, and more preferably 3.00 mmol / g or less. In addition, when the substituent is a carboxymethyl group, the amount of the carboxy group introduced may be 5.8 mmol / g or less per 1 g (mass) of the cellulose fiber. By setting the amount of the carboxy group introduced within the above range, it is possible to facilitate the miniaturization of the cellulose fibers in the miniaturization treatment step and enhance the stability of the fine fibrous cellulose.

<Sulfone group introduction process>
The ionic substituent introduction step may include a sulfone group introduction step. In the sulfone group introduction step, cellulose fibers having a sulfone group (sulfone group-introduced fiber) can be obtained by reacting the hydroxyl group of the fiber raw material containing cellulose with sulfur oxoacid.

In the sulfone group introduction step, at least one selected from compounds capable of introducing a sulfone group by reacting with the hydroxyl group of the fiber raw material containing cellulose instead of the compound A in the above-mentioned <phosphoric acid group introduction step>. A compound (hereinafter, also referred to as “Compound C”) is used. The compound C may be any compound having a sulfur atom and capable of forming an ester bond with cellulose, and examples thereof include sulfuric acid or a salt thereof, sulfite or a salt thereof, sulfuric acid amide, and the like, but the compound C is not particularly limited. As the sulfuric acid, those having various puritys can be used, and for example, 96% sulfuric acid (concentrated sulfuric acid) can be used. Examples of sulfurous acid include 5% sulfurous acid water. Examples of the sulfate or sulfite include lithium salts, sodium salts, potassium salts and ammonium salts of sulfates or sulfites, and these can have various neutralization degrees. As the sulfate amide, sulfamic acid or the like can be used. In the sulfone group introduction step, it is preferable to use the compound B in the above-mentioned <phosphoric acid group introduction step> in the same manner.

In the sulfone group introduction step, it is preferable to mix the cellulose raw material with an aqueous solution containing sulfur oxoacid and urea and / or a urea derivative, and then heat-treat the cellulose raw material. As the heat treatment temperature, it is preferable to select a temperature at which the sulfone group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and even more preferably 150 ° C. or higher. The heat treatment temperature is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 200 ° C. or lower.

In the heat treatment step, it is preferable to heat until the water content is substantially eliminated. Therefore, the heat treatment time varies depending on the amount of water contained in the cellulose raw material and the amount of the aqueous solution containing sulfur oxoacid and urea and / or a urea derivative, but is, for example, 10 seconds or more and 10000 seconds or less. It is preferable to do so. Equipment having various heat media can be used for the heat treatment, for example, a hot air drying device, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, and a fluidized layer drying device. , Band type drying device, filtration drying device, vibration flow drying device, air flow drying device, vacuum drying device, infrared heating device, far infrared heating device, microwave heating device, high frequency drying device can be used.

The amount of the sulfone group introduced into the cellulose raw material is preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g or more, further preferably 0.20 mmol / g or more, and 0. It is more preferably 40 mmol / g or more, further preferably 0.50 mmol / g or more, and particularly preferably 0.60 mmol / g or more. The amount of the sulfone group introduced into the cellulose raw material is preferably 5.00 mmol / g or less, and more preferably 3.00 mmol / g or less. By setting the amount of the sulfone group introduced within the above range, it is possible to facilitate the miniaturization of the cellulose fibers in the micronization treatment step and enhance the stability of the fine fibrous cellulose.

<Oxidation step with chlorine-based oxidant (second carboxy group introduction step)>
The ionic substituent introduction step may include an oxidation step with a chlorine-based oxidizing agent. In the oxidation step using a chlorine-based oxidant, a carboxy group is introduced into the fiber raw material by adding the chlorine-based oxidant to a wet or dry fiber raw material having a hydroxyl group and carrying out a reaction.

Examples of chlorine-based oxidants include hypochlorous acid, hypochlorite, chloric acid, chlorate, chloric acid, chlorate, perchloric acid, perchlorate, and chlorine dioxide. From the viewpoint of introduction efficiency of substituents, defibration efficiency, cost, and ease of handling, the chlorine-based oxidizing agent is preferably sodium hypochlorite, sodium chlorite, or chlorine dioxide. When the chlorine-based oxidizing agent is added, it may be added as it is as a reagent (solid or liquid) to the fiber raw material, or it may be added by dissolving it in an appropriate solvent.

The concentration of the chlorine-based oxidant in the solution in the oxidation step using the chlorine-based oxidant is preferably 1% by mass or more and 1,000% by mass or less in terms of effective chlorine concentration, and is 5% by mass or more and 500% by mass or less. It is more preferably 10% by mass or more and 100% by mass or less. The amount of the chlorine-based oxidizing agent added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 10 parts by mass or more and 10,000 parts by mass or less, and 100 parts by mass. It is more preferable that the amount is 5,000 parts by mass or more.

The reaction time with the chlorine-based oxidizing agent in the oxidation step using the chlorine-based oxidizing agent may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, and is preferably 10 minutes or more and 500 minutes or less. More preferably, it is more preferably 20 minutes or more and 400 minutes or less. The pH at the time of reaction is preferably 5 or more and 15 or less, more preferably 7 or more and 14 or less, and further preferably 9 or more and 13 or less. Further, at the start of the reaction, it is preferable that the pH during the reaction is kept constant (for example, pH 11) while appropriately adding hydrochloric acid or sodium hydroxide. Further, after the reaction, excess reaction reagents, by-products and the like may be washed and removed by filtration or the like.

<Zantate group introduction step (xanthate esterification step)>
The ionic substituent introduction step may include, for example, a zantate group introduction step (hereinafter, also referred to as a zantate conversion step). In the zantate formation step, a zantate group is introduced into the fiber raw material by adding carbon disulfide and an alkaline compound to a wet or dry fiber raw material having a hydroxyl group and carrying out a reaction. Specifically, carbon disulfide is added to the alkali-cellulose-ized fiber raw material by the method described later, and the reaction is carried out.

<< Alkaline Cellulose >>
When introducing an ionic substituent into a fiber raw material, it is preferable to allow an alkaline solution to act on the cellulose contained in the fiber raw material to convert the cellulose into alkaline cellulose. By this treatment, a part of the hydroxyl groups of cellulose is ion-dissociated, and the nucleophilicity (reactivity) can be enhanced. The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkaline compound or an organic alkaline compound. For example, sodium hydroxide, potassium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide are preferably used because of their high versatility. Alkali celluloseization may be carried out at the same time as the introduction of the ionic substituent, may be carried out as a pre-stage thereof, or may be carried out at both timings.

The solution temperature at the start of alkaline cellulose formation is preferably 0 ° C. or higher and 50 ° C. or lower, more preferably 5 ° C. or higher and 40 ° C. or lower, and further preferably 10 ° C. or higher and 30 ° C. or lower.

The alkali concentration in the alkaline solution is preferably 0.01 mol / L or more and 4 mol / L or less, more preferably 0.1 mol / L or more and 3 mol / L or less, and 1 mol / L or more 2 It is more preferably 5.5 mol / L or less. In particular, when the treatment temperature for alkali celluloseization is less than 10 ° C., the alkali concentration is preferably 1 mol / L or more and 2 mol / L or less.

The treatment time for alkali celluloseization is preferably 1 minute or longer, more preferably 10 minutes or longer, and even more preferably 30 minutes or longer. The alkali treatment time is preferably 6 hours or less, more preferably 5 hours or less, and even more preferably 4 hours or less.

By adjusting the type, treatment temperature, concentration, and immersion time of the alkaline solution as described above, the permeation of the alkaline solution into the crystal region of cellulose can be suppressed, the crystal structure of cellulose type I can be easily maintained, and the cellulose is in the form of fine fibers. The yield of cellulose can be increased.

When the introduction of the ionic substituent and the alkali celluloseization are not performed at the same time, it is preferable that the alkali celluloseization is performed before the introduction of the ionic substituent. In this case, it is preferable that the alkali cellulose obtained by the alkali celluloseization treatment is solid-liquid separated to remove water by a general deliquidation method such as centrifugation or filtration. This improves the reaction efficiency in the subsequent ionic substituent introduction step. The cellulose fiber concentration after solid-liquid separation is preferably 5% or more and 50% or less, more preferably 10% or more and 40% or less, and further preferably 15% or more and 35% or less.

<Phosphon group or phosphine group introduction step (phosphoalkylation step)>
The ionic substituent introduction step may include a phosphon group or phosphine group introduction step (phosphoalkylation step). In the phosphoalkylation step, a compound having a reactive group and a phospho group or a phosphine group (Compound E _A ) as an essential component, an alkaline compound as an optional component, and a compound B selected from the above-mentioned urea and its derivatives are wetted. Alternatively, a phosphone group or a phosphine group is introduced into the fiber raw material by carrying out the reaction in addition to the fiber raw material having a hydroxyl group in a dry state.

Examples of the reactive group include an alkyl halide group, a vinyl group, an epoxy group (glycidyl group) and the like.
The compound E _A, e.g. vinyl phosphoric acid, phenyl vinyl phosphonic acid, and phenyl vinyl phosphinic acid. Introduction efficiency of substituents, and thus solution繊効rate, cost, compounds from the viewpoint of easy handling E _A is preferably a vinyl phosphoric acid.
Further, as an optional component, the compound B in the above-mentioned <phosphoric acid group introduction step> is also preferably used in the same manner, and the addition amount is preferably as described above.

When adding a compound E _A may be added directly to the fiber material as a reagent (solid or liquid), it may be added dissolved in a suitable solvent. It is preferable that the fiber raw material is made into alkali cellulose in advance or is made into alkali cellulose at the same time as the reaction. The method of alkali celluloseization is as described above.

The temperature during the reaction is, for example, preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower.

Amount for fiber material 100 parts by weight of Compound _{E A} is preferably not more than 100,000 parts by 1 part by mass or more, more preferably at most 10,000 parts by mass or more, 2 parts by mass 5 parts by weight It is more preferably 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and 20 minutes or more and 400 minutes or less. Is even more preferable. Further, after the reaction, excess reaction reagents, by-products and the like may be washed and removed by filtration or the like.

<Sulfone group introduction step (sulfoalkylation step) (second sulfone group introduction step)>
The ionic substituent introduction step may include a sulfone group introduction step (sulfoalkylation step). In sulfoalkylated, as essential components, a compound having a reactive group and a sulfonic group (Compound E _B), an alkaline compound as an optional component, a compound B which is selected from urea and its derivatives mentioned above, wet or dry By carrying out the reaction in addition to the fiber raw material having a hydroxyl group, a sulfone group is introduced into the fiber raw material.

Examples of the reactive group include an alkyl halide group, a vinyl group, an epoxy group (glycidyl group) and the like.
The compound E _B, 2-sodium chloroethane sulfonate, sodium vinyl sulfonate, p- sodium styrenesulfonate, 2-acrylamido-2-methylpropane sulfonic acid. Of these, the introduction efficiency of the substituents, and thus solution繊効rate, cost, vinyl compounds from the viewpoint of easy handling E _B is preferably a sodium sulfonate.
Further, as an optional component, the compound B in the above-mentioned <phosphoric acid group introduction step> is also preferably used in the same manner, and the addition amount is preferably as described above.

When adding the compound E _B may be added directly to the fiber material as a reagent (solid or liquid), it may be added dissolved in a suitable solvent. It is preferable that the fiber raw material is made into alkali cellulose in advance or is made into alkali cellulose at the same time as the reaction. The method of alkali celluloseization is as described above.

Amount for fiber material 100 parts by weight of compound _{E B} is preferably not more than 100,000 parts by 1 part by mass or more, more preferably at most 10,000 parts by mass or more, 2 parts by mass 5 parts by weight It is more preferably 1,000 parts by mass or less.

<Carboxyalkylation step (third carboxy group introduction step)>
The ionic substituent introduction step may include a carboxyalkylation step. As essential components, a compound having a reactive group and a carboxy group (Compound E _C), alkaline compound as an optional component, a compound B which is selected from urea and its derivatives mentioned above, the wet or dry state, the fiber having a hydroxyl group By carrying out the reaction in addition to the raw material, a carboxy group is introduced into the fiber raw material.

Examples of the reactive group include an alkyl halide group, a vinyl group, an epoxy group (glycidyl group) and the like.
The compound E _C, introduction efficiency of the substituents, and thus solution繊効rate, cost, ease of handling monochloroacetic acid in terms of sodium monochloroacetate, 2-chloropropionic acid, sodium 2-chloropropionic acid is preferred.
Further, as an optional component, the compound B in the above-mentioned <phosphoric acid group introduction step> is also preferably used in the same manner, and the addition amount is preferably as described above.

When adding the compound E _C may be added directly to the fiber material as a reagent (solid or liquid), it may be added dissolved in a suitable solvent. It is preferable that the fiber raw material is made into alkali cellulose in advance or is made into alkali cellulose at the same time as the reaction. The method of alkali celluloseization is as described above.

Amount for fiber material 100 parts by weight of compound _{E C} is preferably not more than 100,000 parts by 1 part by mass or more, more preferably at most 10,000 parts by mass or more, 2 parts by mass 5 parts by weight It is more preferably 1,000 parts by mass or less.

<Cationic group introduction step (cationization step)>
A compound having a reactive group and a cationic group (Compound _ED ) as an essential component, an alkaline compound as an optional component, and a compound B selected from the above-mentioned urea and its derivatives have a hydroxyl group in a wet or dry state. By carrying out the reaction in addition to the fiber raw material, a cationic group is introduced into the fiber raw material.

Examples of the reactive group include an alkyl halide group, a vinyl group, an epoxy group (glycidyl group) and the like.
Examples of the cationic group include an ammonium group, a phosphonium group, a sulfonium group and the like. Of these, the cationic group is preferably an ammonium group.
The compound E _D, introduction efficiency of the substituents, and thus solution繊効rate, cost, ease of handling glycidyl trimethyl ammonium chloride from the viewpoint of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride are preferred.
Further, as an optional component, it is also preferable to similarly use the compound B in the above-mentioned <phosphoric acid group introduction step>. The amount of addition is also preferably as described above.

When adding the compound E _D may be added directly to the fiber material as a reagent (solid or liquid), it may be added dissolved in a suitable solvent. It is preferable that the fiber raw material is made into alkali cellulose in advance or is made into alkali cellulose at the same time as the reaction. The method of alkali celluloseization is as described above.

Amount for fiber material 100 parts by weight of Compound _{E D} is preferably not more than 100,000 parts by 1 part by mass or more, more preferably at most 10,000 parts by mass or more, 2 parts by mass 5 parts by weight It is more preferably 1,000 parts by mass or less.

<Washing process>
In the step of obtaining the cellulose fiber having an ionic substituent, a washing step can be performed on the ionic substituent-introduced fiber, if necessary. The washing step is performed by washing the ionic substituent-introduced fiber with, for example, water or an organic solvent. Further, the cleaning step may be performed after each step described later, and the number of cleanings performed in each cleaning step is not particularly limited.

<Alkaline treatment process>
In the step of obtaining the cellulose fiber having an ionic substituent, an alkali treatment step may be provided between the ionic substituent introduction step and the miniaturization treatment step. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the ionic substituent-introduced fiber in an alkaline solution.

The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkaline compound or an organic alkaline compound. In the present embodiment, for example, sodium hydroxide or potassium hydroxide is preferably used as the alkaline compound because of its high versatility. Further, the solvent contained in the alkaline solution may be either water or an organic solvent. Among them, the solvent contained in the alkaline solution is preferably a polar solvent containing water or a polar organic solvent exemplified by alcohol, and more preferably an aqueous solvent containing at least water. As the alkaline solution, for example, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is preferable because of its high versatility.

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time of the ionic substituent-introduced fiber in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10000% by mass or less, based on the absolute dry mass of the ionic substituent-introduced fiber. The following is more preferable.

In order to reduce the amount of the alkaline solution used in the alkali treatment step, the ionic substituent introduction fiber may be washed with water or an organic solvent after the ionic substituent introduction step and before the alkali treatment step. After the alkali treatment step and before the miniaturization treatment step, it is preferable to wash the alkali-treated ionic substituent-introduced fiber with water or an organic solvent from the viewpoint of improving handleability.

<Acid treatment process>
In the step of obtaining the cellulose fiber having an ionic substituent, an acid treatment step may be provided between the ionic substituent introduction step and the miniaturization treatment step. For example, the ionic substituent introduction step, the acid treatment, the alkali treatment, and the micronization treatment may be performed in this order.

The method of acid treatment is not particularly limited, and examples thereof include a method of immersing the fiber raw material in an acidic solution containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably 10% by mass or less, and more preferably 5% by mass or less, for example. The pH of the acidic solution used is not particularly limited, but is preferably 0 or more and 4 or less, and more preferably 1 or more and 3 or less. As the acid contained in the acidic solution, for example, an inorganic acid, a sulfonic acid, a carboxylic acid or the like can be used. Examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, phosphoric acid, boric acid and the like. Examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. Examples of the carboxylic acid include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, tartaric acid and the like. Among these, it is particularly preferable to use hydrochloric acid or sulfuric acid.

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the fiber raw material. Is more preferable.

(Nanocarbon precursor)
The nanocarbon precursor is a precursor that becomes carbon nanotubes or graphene by miniaturization treatment. It can be said that the nanocarbon precursor is a bulk structure of carbon nanotubes and graphene. That is, the nanocarbon precursor is a structure in which carbon nanotubes and graphene are aggregated.

The nanocarbon precursor has cationic properties. Therefore, when the cellulose fiber has an anionic group as an ionic substituent, the nanocarbon precursor and the cellulose fiber are bonded by the electric charge of each material. Then, while maintaining such a bonded state, a mixed solution containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent is subjected to a micronization treatment step, whereby fine fibrous cellulose It becomes easy to obtain fine fibrous cellulose / nanocarbon-containing material in which nanocarbon and nanocarbon are compounded. If the nanocarbon precursor and the cellulose fiber are mixed in a nano-sized state, strong aggregation is formed due to the electric charge of each material, and it is considered that the dispersibility is deteriorated.

In the present specification, the particle size of the nanocarbon precursor is more than 1 μm and 1000 μm or less. When one molecule of the nanocarbon precursor is not spherical, the length, width, and thickness of the nanocarbon precursor are all more than 1 μm and 1000 μm or less. Such a nanocarbon precursor may be in the form of pellets compacted by a method such as pressing.

Commercially available products can also be used for the nanocarbon precursor. Examples of commercially available products include MWCNT (LUCAN CP1001M) manufactured by LG Chem and phosphonic graphite (Z-5F) manufactured by Ito Graphite. In addition, a commercially available product as described above may be combined and used as a nanocarbon precursor.

(Arbitrary ingredient)
The mixed solution containing the cellulose fiber having an ionic substituent, the nanocarbon precursor, and the solvent used in the micronization treatment step may contain an arbitrary component in addition to the cellulose fiber and the nanocarbon precursor. good. Examples of the optional component include vegetable oil, animal oil, mineral oil, resin, resin emulsion, inorganic particles, layered inorganic compound and the like. Among them, vegetable oils, animal oils, and mineral oils are preferably used because they have good compatibility with nanocarbon precursors.

The content of the surfactant in the mixture containing the cellulose fiber having an ionic substituent, the nanocarbon precursor and the solvent is preferably 1% by mass or less, preferably 0.1% by mass or less. Is more preferable. That is, it is preferable that the mixture containing the cellulose fiber having an ionic substituent, the nanocarbon precursor, and the solvent does not substantially contain a surfactant. By setting the content of the surfactant in the mixture containing the cellulose fiber having an ionic substituent, the nanocarbon precursor, and the solvent within the above range, the occurrence of bubbling can be suppressed more effectively. ..

(Fine fibrous cellulose / nanocarbon-containing material)
The present embodiment is also a fine fibrous cellulose / nanocarbon-containing product having a fiber width of 1000 nm or less and containing fine fibrous cellulose having an ionic substituent and nanocarbon. The thixotropic index value (TI value) calculated under the following condition a of the fine fibrous cellulose / nanocarbon-containing material of the present embodiment is 2 or more.
(Condition a)
The fine fibrous cellulose / nanocarbon-containing material is dispersed in water to obtain a dispersion having a viscosity of 1000 cps measured at 23 ° C. with a B-type viscometer at a rotation speed of 3 rpm; 23 ° C. with a B-type viscometer. The viscosity (η) of the dispersion measured at a rotation speed of 60 rpm is measured, and a value of 1000 / η is defined as a thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing material.

In the present specification, the initial viscosity (1000 cps) used for calculating the thixotropic index value (TI value) is a value measured by a B-type viscometer (analog viscometer T-LVT manufactured by BLOOKFIELD). The measurement condition is a rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement is measured. The fine fibrous cellulose / nanocarbon dispersion is appropriately diluted with ion-exchanged water so that the viscosity value at this time is 1000 cps, but the viscosity (initial viscosity) after dilution has an error of about ± 10%. You may. For example, the initial viscosity can be adjusted to about 1000 cps by adjusting the content of the fine fibrous cellulose / nanocarbon to the total mass of the dispersion liquid to 0.3 to 3.0% by mass. After diluting the fine fibrous cellulose / nanocarbon dispersion with ion-exchanged water, the mixture is stirred with a disperser at 1500 rpm for 5 minutes and allowed to stand in an environment of 23 ° C. and 50% relative humidity for 24 hours before measurement. After that, the viscosity is measured. The liquid temperature of the dispersion used for the viscosity measurement is 23 ° C. ・ After measuring the initial viscosity, the viscosity (η) of the dispersion measured at 23 ° C. and 60 rpm with a B-type viscometer. To measure. Then, the value of 1000 / η is taken as the thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing material.

The thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing material is preferably 2 or more, more preferably 5 or more, and further preferably 10 or more. The thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing material is preferably 1000 or less, more preferably 500 or less, and further preferably 300 or less. When the thixotropic index value (TI value) is at least the above lower limit value, a fine fibrous cellulose / nanocarbon-containing product having high thixotropy can be obtained.

The content of the solvent in the fine fibrous cellulose / nanocarbon-containing material is preferably 99% by mass or less, more preferably 98% by mass or less, based on the total mass of the fine fibrous cellulose / nanocarbon-containing material. preferable. The content of the solvent in the fine fibrous cellulose / nanocarbon-containing material may be 95% by mass or less, or 90% by mass or less, based on the total mass of the mixture. The lower limit of the solvent content in the fine fibrous cellulose / nanocarbon-containing material is not particularly limited, but is, for example, 70% by mass or more with respect to the total mass of the fine fibrous cellulose / nanocarbon-containing material.

The fine fibrous cellulose and nanocarbon are uniformly dispersed in the fine fibrous cellulose / nanocarbon-containing material. Here, the state in which the fine fibrous cellulose and the nanocarbon are uniformly dispersed is one liquid in which the fine fibrous cellulose / nanocarbon dispersion liquid is continuous, and the fine fibrous cellulose / nanocarbon dispersion liquid is visually observed. In this case, it means a state in which only the fine fibrous cellulose dispersion is present and there is no portion in which only the nanocarbon dispersion is present. On the other hand, if the dispersion liquids are separated into a plurality of parts, or if the parts where only the fine fibrous cellulose dispersion liquid is present and the parts where only the nanocarbon dispersion liquid is present are sparsely present, it can be determined that the dispersion is not uniformly dispersed. ..

The value (CV value) obtained by dividing the standard deviation of the post-combustion mass ratio of the fine fibrous cellulose / nanocarbon-containing material by the average value of the post-combustion mass ratio of the fine fibrous cellulose / nanocarbon-containing material is less than 10%. It is preferably less than 5% (lower limit: 0%). Here, the standard deviation of the mass ratio of the fine fibrous cellulose / nanocarbon-containing material after combustion is determined by using a differential thermogravimetric simultaneous measuring device (TG / DTA6300 manufactured by Seiko Instruments Co., Ltd. (currently Hitachi High-Tech Science Co., Ltd.)). Is measured. Specifically, 1 cc of a sample randomly collected from the obtained fine fibrous cellulose / nanocarbon-containing material (dispersion liquid) was heated in a nitrogen atmosphere according to the following temperature program, and once per second. Weigh. Next, the ratio of the weight when the temperature reaches 600 ° C. (the ratio of the mass after combustion) to the weight at 110 ° C. is calculated, and the standard deviation of the mass ratio after combustion is obtained by measuring 10 times.
<Temperature program>
Hold at 1.50 ° C for 5 minutes Increase temperature from 2.50 ° C to 100 ° C (heating rate: 10 ° C / min)
3. Hold at 100 ° C for 10 minutes 4. Raise the temperature from 100 ° C to 600 ° C (heating rate: 10 ° C / min)
The mass ratio of the fine fibrous cellulose / nanocarbon-containing material after combustion is the value obtained by dividing the following α by β (value of α / β), and the CV value is measured to calculate the value of α / β. Is performed 10 times, and the standard deviation of the α / β values is divided by the average value of the α / β values.
α: Mass after combustion of fine fibrous cellulose / nanocarbon-containing material (mass when reaching 600 ° C)
β: Absolute dry mass of fine fibrous cellulose / nanocarbon-containing material (mass when reaching 110 ° C)

In the fine fibrous cellulose / nanocarbon-containing material, at least a part of the fine fibrous cellulose and nanocarbon are compounded. Here, the compounding means a state in which at least a part of the fine fibrous cellulose and the nanocarbon are in contact with each other.

(Fine fibrous cellulose)
The fine fibrous cellulose contained in the fine fibrous cellulose / nanocarbon-containing material is a fine fibrous cellulose having a fiber width of 1000 nm or less. The fiber width of the fine fibrous cellulose is more preferably 100 nm or less, and further preferably 8 nm or less. In the present specification, fibrous cellulose having a fiber width of 1000 nm or less is referred to as fine fibrous cellulose.

The fiber width of fine fibrous cellulose can be measured by, for example, observation with an electron microscope. The average fiber width of the fine fibrous cellulose is, for example, 1000 nm or less. The average fiber width of the fine fibrous cellulose is, for example, preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more and 10 nm or less. Is particularly preferable. By setting the average fiber width of the fine fibrous cellulose to 2 nm or more, it is possible to suppress the dissolution of the fine fibrous cellulose in water as a cellulose molecule, and to more easily exhibit the effects of the fine fibrous cellulose to improve strength, rigidity and dimensional stability. be able to. The fine fibrous cellulose is, for example, monofibrous cellulose.

The average fiber width of fine fibrous cellulose is measured as follows, for example, using an electron microscope. First, an aqueous suspension of fine fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast on a hydrophilized carbon film-coated grid for TEM observation. Use as a sample. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Next, observation is performed using an electron microscope image at a magnification of 1000 times, 5000 times, 10000 times, or 50,000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification should be adjusted so as to satisfy the following conditions.

(1) A straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.

For an observation image that satisfies the above conditions, visually read the width of the fiber that intersects the straight line X and the straight line Y. In this way, at least three sets of observation images of surface portions that do not overlap each other are obtained. Next, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. As a result, at least 20 fibers × 2 × 3 = 120 fibers are read. Then, the average value of the read fiber widths is taken as the average fiber width of the fine fibrous cellulose.

The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and 0.1 μm or more and 600 μm or less. More preferred. By setting the fiber length within the above range, destruction of the crystal region of the fine fibrous cellulose can be suppressed. It is also possible to set the slurry viscosity of the fine fibrous cellulose in an appropriate range. The fiber length of the fine fibrous cellulose can be obtained by, for example, image analysis by TEM, SEM, or AFM.

The fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has an I-type crystal structure can be identified in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatic with graphite. Specifically, it can be identified by having typical peaks at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. The ratio of the type I crystal structure to the fine fibrous cellulose is, for example, preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. As a result, even better performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion. The crystallinity is determined by a conventional method from the X-ray diffraction profile measured and the pattern (Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

The axial ratio (fiber length / fiber width) of the fine fibrous cellulose is not particularly limited, but is preferably 20 or more and 10000 or less, and more preferably 50 or more and 1000 or less. By setting the axial ratio to the above lower limit value or more, it is easy to form a sheet containing fine fibrous cellulose. In addition, sufficient viscosity can be easily obtained when the solvent dispersion is produced. By setting the axial ratio to the above upper limit value or less, for example, when treating fine fibrous cellulose as an aqueous dispersion, it is preferable in that handling such as dilution becomes easy.

The fine fibrous cellulose in the present embodiment has, for example, both a crystalline region and a non-crystalline region. The fine fibrous cellulose having both a crystalline region and an amorphous region and having an axial ratio within the above range is realized by a method for producing fine fibrous cellulose described later.

The fine fibrous cellulose of the present embodiment has an ionic substituent. The ionic substituent can include, for example, either one or both of an anionic group and a cationic group. In this embodiment, it is particularly preferable to have an anionic group as the ionic substituent.

Examples of the anionic group include a phosphoric acid group or a substituent derived from a phosphoric acid group (sometimes simply referred to as a phosphoric acid group), a carboxy group or a substituent derived from a carboxy group (sometimes simply referred to as a carboxy group), and the like. Examples thereof include a sulfone group or a substituent derived from the sulfone group (sometimes referred to simply as a sulfon group), a zantate group, a phosphone group, a phosphine group, a carboxyalkyl group (including a carboxymethyl group) and the like. When a sulfone group or a substituent derived from a sulfone group is introduced via an ester bond, the substituent is referred to as a sulfur oxo acid group or a substituent derived from a sulfur oxo acid group (simply referred to as a sulfur oxo acid group). There is also). Among them, the anionic group is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a carboxymethyl group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. It is preferably a species, and is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. Is more preferable, and a phosphorusoxo acid group is particularly preferable. As the phosphate group or the substituent derived from the phosphorusoxo acid group, the substituent represented by the above-mentioned formula (1) can be similarly exemplified. Examples of the cationic group as the ionic substituent include an ammonium group, a phosphonium group, a sulfonium group and the like. Of these, the cationic group is preferably an ammonium group.

The amount of the ionic substituent introduced into the fine fibrous cellulose is preferably, for example, 0.05 mmol / g or more, more preferably 0.10 mmol / g or more, and 0, per 1 g (mass) of the fine fibrous cellulose. It is more preferably 20 mmol / g or more, further preferably 0.40 mmol / g or more, and particularly preferably 0.60 mmol / g or more. The amount of the ionic substituent introduced into the fine fibrous cellulose is preferably 5.20 mmol / g or less per 1 g (mass) of the fine fibrous cellulose, and more preferably 3.65 mmol / g or less. , 3.00 mmol / g or less, more preferably. Here, the denominator in the unit mmol / g indicates the mass of the fine fibrous cellulose when the counter ion of the ionic substituent is a hydrogen ion (H ^+). By setting the amount of the ionic substituent introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous cellulose.

(Nanocarbon)
Examples of the nanocarbon contained in the fine fibrous cellulose / nanocarbon-containing material include carbon nanotubes (CNT), graphene, and fullerenes. Above all, the nanocarbon is preferably at least one selected from the group consisting of carbon nanotubes and graphene. The carbon nanotube (CNT) may be a single-walled carbon nanotube (CNT) or a multi-walled carbon nanotube (CNT). Similarly, graphene may be single-layer graphene or multi-layer graphene.

In the present specification, the nanocarbon means nanocarbon particles having a particle size of 1000 nm or less. When one molecule of nanocarbon is not spherical, nanocarbon is nanocarbon particles in which at least one of length, width, and thickness is 1000 nm or less. The length of one side of the nanocarbon particles is a value measured by observing the observation sample obtained after casting the dispersion liquid of nanocarbon with an electron microscope after appropriately dyeing the sample as necessary. Is.

(Use)
Applications of the fine fibrous cellulose / nanocarbon-containing material of the present embodiment include paints, resin compositions, concrete materials, filamentous or plate-like structures, electromagnetic wave shields, electrochemical devices and the like. The electrochemical device includes a battery, a capacitor (capacitor), and an electric double layer capacitor. Further, the thread-like or plate-like structure includes a sheet, a film, a film, and a non-woven fabric. That is, another embodiment of the present invention is the above-mentioned fine fibrous cellulose / nanocarbon-containing material in the production of paints, resin compositions, concrete materials, filamentous or plate-like structures, electromagnetic wave shields or electrochemical devices. Is used.

When the fine fibrous cellulose / nanocarbon-containing material of the present embodiment is used for the resin composition, the fine fibrous cellulose / nanocarbon-containing material may be included as an additive of the resin composition, and the resin component is fine. It may be included as an additive of the fibrous cellulose / nanocarbon-containing material. Examples of the resin component contained in the resin composition include rubber-based resin, polyolefin resin, acrylic resin, urethane resin, polycarbonate resin and the like.

The present embodiment may be a paint containing the above-mentioned fine fibrous cellulose / nanocarbon-containing material, may be a concrete material containing the fine fibrous cellulose / nanocarbon-containing material, and may be a fine fibrous cellulose / nano. It may be a filamentous or plate-like structure containing carbon-containing material, an electromagnetic wave shield containing fine fibrous cellulose / nanocarbon-containing material, and electrochemical containing fine fibrous cellulose / nanocarbon-containing material. It may be a device. Known components of paints, concrete materials, electromagnetic wave shields and electrochemical devices can be mentioned.

The features of the present invention will be described in more detail below with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below.

<Production example A1>
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 250 seconds to introduce a phosphoric acid group into the cellulose in the pulp to obtain a phosphorylated pulp.

Next, the obtained phosphorylated pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. went. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

Next, the phosphorylated pulp after washing was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated and washed to obtain a phosphorylated pulp that had been neutralized. Then, ion-exchanged water was added to the obtained phosphorylated pulp to prepare a dispersion liquid having a concentration of 0.5% by mass, and the neutralization treatment of the cellulose fibers was completed.

The infrared absorption spectrum of the obtained phosphorylated pulp was measured using FT-IR. As a result, absorption ^{of the phosphate group based on P = O was observed around 1230 cm -1} , and it was confirmed that the phosphate group was added to the pulp. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals. The amount of phosphate groups (first dissociated acid amount, strongly acidic group amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mol / g.

<Manufacturing example A2>
The 0.5% by mass dispersion of phosphorylated pulp obtained in Production Example A1 was treated once with a high-pressure homogenizer (Beryu-Mini, manufactured by Bigrain Co., Ltd.) at a pressure of 100 MPa. This device is equipped with a bubbling suppression mechanism. The high-pressure homogenizer includes a jet flow generator provided with a diamond nozzle and a bubbling suppression mechanism located downstream of the jet flow generator. In this device, a coolable pipe (cloak) was adopted as a bubbling suppression mechanism, and such a pipe (cloak) was arranged so as to cover the inner pipe through which the dispersion liquid flows. The length of the coolable pipe was 350 mm, and the coolable pipe was installed on the downstream side of the diamond nozzle 100 mm of the jet flow generating portion. In this bubbling suppression mechanism, while applying back pressure to the jet flow generated by the diamond nozzle, cooling water at 15 ° C. was flowed through the mantle at a flow rate of 27 L / min. In this way, a pretreated 0.5% by mass concentration cellulose fiber dispersion was obtained. When the obtained cellulose fiber dispersion was observed with an optical microscope, many cellulose fibers having a width of 20 μm or more were observed.

<Manufacturing example A3>
In the neutralization treatment, the same operation as in Production Example A1 was carried out except that tetrabutylammonium hydroxide having a concentration of 40% by mass was used instead of sodium hydroxide to obtain a cellulose fiber dispersion having a concentration of 0.5% by mass. rice field. Cellulose fibers had tetrabutylammonium ions (TBA ⁺ ) as counterions.

<Manufacturing example B1>
The same procedure as in Production Example A1 was carried out except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate to obtain phosphorous oxide pulp. Others were operated in the same manner as in Production Example A1 to obtain a cellulose fiber dispersion having a concentration of 0.5% by mass.

The infrared absorption spectrum of the obtained subphosphorylated pulp was measured using FT-IR. As a result, absorption based on P = O of the phosphonic acid group, which is a tautomer of the phosphite group, was observed around ^{1210 cm -1, and the phosphite group (phosphonic acid group) was added to the pulp.} Was confirmed. Further, when the obtained subphosphorylated pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example C1>
38 parts by mass of amide sulfuric acid (sulfamic acid) was used instead of ammonium dihydrogen phosphate, and the same procedure as in Production Example A1 was carried out except that the heating time was extended to 19 minutes to obtain sulfated pulp. Others were operated in the same manner as in Production Example A1 to obtain a cellulose fiber dispersion having a concentration of 0.5% by mass.

The infrared absorption spectrum of the obtained sulfated pulp was measured using FT-IR. As a result, absorption of the sulfate ester group based on S = O was observed in the vicinity of ^{1220-1260 cm -1, and it was confirmed that the sulfate ester group was added to the pulp.} Further, when the obtained sulfated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals. The amount of sulfate ester groups (first dissociated acid amount) measured by the measuring method described in [Measurement of sulfate ester group amount] described later was 1.12 mmol / g.

<Manufacturing example D1>
As the raw material pulp, softwood kraft pulp (undried) made by Oji Paper was used. Alkaline TEMPO oxidation treatment was carried out on this raw material pulp as follows.

First, the raw material pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10000 parts by mass of water. It was dispersed in the parts. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so as to be 10 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change was observed in the pH.

Next, the obtained TEMPO oxide pulp was washed. The washing treatment is carried out by dehydrating the pulp slurry after TEMPO oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtration and dehydration. rice field. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

The dehydrated sheet was subjected to additional oxidation treatment of the remaining aldehyde groups as follows. The dehydrated sheet corresponding to 100 parts by mass of dry mass was dispersed in 10000 parts by mass of 0.1 mol / L acetate buffer (pH 4.8). Next, 113 parts by mass of 80% by mass sodium chlorite was added, and the mixture was immediately sealed and then reacted at room temperature for 48 hours with stirring at 500 rpm using a magnetic stirrer to obtain a pulp slurry.

Next, the obtained top-oxidized TEMPO oxide pulp was washed. The washing treatment is carried out by dehydrating the pulp slurry after the additional oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtering and dehydrating. rice field. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set. Then, ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a dispersion liquid having a concentration of 0.5% by mass, and the neutralization treatment of the cellulose fibers was completed.

Regarding the obtained TEMPO oxidized pulp, the amount of carboxy group measured by the measuring method described later was 1.80 mmol / g. Further, when the obtained TEMPO oxide pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, confirming that it had cellulose type I crystals.

<Manufacturing example E1>
[Oxidation of hypochlorous acid]
A sheet (solid content concentration 90% by mass) made from softwood bleached kraft pulp (NBKP) is treated with a hand mixer (Osaka Chemical Co., Ltd., Lab Miller PLUS) at a rotation speed of 20000 rpm for 15 seconds to form a cotton-like fluffing. It was made into pulp (solid content concentration 90% by mass). Next, sodium hypochlorite pentahydrate was added to ion-exchanged water to prepare an aqueous solution having a solid content concentration of sodium hypochlorite of 22% by mass. To 100 parts by mass of cotton-like fluffing pulp, 9000 parts by mass of a 22% by mass sodium hypochlorite aqueous solution was added and reacted in a warm bath at 30 ° C. for 2 hours to obtain a carboxy group-introduced pulp. During the reaction, a 1N aqueous sodium hydroxide solution was appropriately added to maintain the pH at 11.

Next, the obtained carboxy group-introduced pulp was washed. The washing treatment was carried out by repeating the operation of pouring ion-exchanged water into the obtained carboxy group-introduced pulp, stirring the pulp dispersion liquid so that the pulp was uniformly dispersed, and then filtering and dehydrating the pulp. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

Regarding the obtained carboxy group-introduced pulp, the amount of carboxy group measured by the measuring method described later was 0.70 mmol / g. Further, when the obtained carboxy group-introduced pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example F1>
[Maleic acid esterification]
A sheet (solid content concentration 90% by mass) made from softwood bleached kraft pulp (NBKP) is treated with a hand mixer (Osaka Chemical Co., Ltd., Lab Miller PLUS) at a rotation speed of 20000 rpm for 15 seconds to form a cotton-like fluffing. It was made into pulp (solid content concentration 90% by mass). The autoclave was filled with 100 parts by mass of cotton-like fluffing pulp and 50 parts by mass of maleic anhydride, and treated at 150 ° C. for 2 hours to obtain a carboxy group-introduced pulp.

The infrared absorption spectrum of the obtained carboxy group-introduced pulp was measured using FT-IR. As a result, absorption based on the carboxy group was observed near 1580 and 1720 cm- ¹ , and it was confirmed that the maleic acid was esterified. Regarding the obtained carboxy group-introduced pulp, the amount of carboxy group measured by the measuring method described later was 1.22 mmol / g. Further, when the carboxy group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example G1>
[Carboxyethylation]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

To 100 parts by mass (absolute dry mass) of this raw material pulp, 250 parts by mass of a 12N NaOH aqueous solution, 163 parts by mass of 2-chloropropionic acid, and 140 parts by mass of ion-exchanged water are added to a chemical solution (total 553 parts by mass). Impregnated pulp was obtained. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 10 minutes to introduce a carboxyethyl group (carboxy group) into the cellulose in the pulp to obtain a carboxy group-introduced pulp.

Next, the carboxy group-introduced pulp after washing was neutralized as follows. First, the washed carboxy group-introduced pulp is diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution is added little by little with stirring to obtain a carboxy group-introduced pulp slurry having a pH of 12 or more and 13 or less. Obtained. Next, the carboxy group-introduced pulp slurry was dehydrated and washed to obtain a neutralized carboxy group-introduced pulp. Then, ion-exchanged water was added to the obtained carboxy group-introduced pulp to prepare a dispersion liquid having a concentration of 0.5% by mass, and the neutralization treatment of the cellulose fibers was completed.

Regarding the obtained carboxy group-introduced pulp, the amount of carboxy group measured by the measuring method described later was 1.41 mmol / g. Further, when the carboxy group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example H1>
[Sulfothethylation]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

To 100 parts by mass (absolute dry mass) of this raw material pulp, a chemical solution (960 parts by mass in total) consisting of 180 parts by mass of a 2N NaOH aqueous solution and 780 parts by mass of a 25 mass% sodium vinyl sulfonate aqueous solution was added to add a chemical solution-impregnated pulp. Obtained. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 16 minutes to introduce a sulfoethyl group (sulfone group) into the cellulose in the pulp to obtain a sulfoethyl group-introduced pulp (sulfone group-introduced pulp).

Next, the obtained sulfoethyl group-introduced pulp was washed. The washing treatment was carried out by repeating the operation of pouring ion-exchanged water into the obtained sulfoethyl group-introduced pulp, stirring the pulp dispersion liquid so that the pulp was uniformly dispersed, and then filtering and dehydrating the pulp. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

Regarding the obtained sulfoethyl group-introduced pulp, the amount of sulfoethyl group (sulfone group amount) measured by the measuring method described later was 1.48 mmol / g. Further, when the sulfoethyl group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example J1>
[Cationation treatment]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

To 100 parts by mass (absolute dry mass) of this raw material pulp, 180 parts by mass of 1N NaOH aqueous solution and a cationizing agent (Catiomaster G, manufactured by Yokkaichi Synthetic Co., Ltd., glycidyltrimethylammonium chloride, pure content 73.1% by mass, water content A chemical solution (total of 505 parts by mass) consisting of 325 parts by mass (20.2% by mass) was added to obtain a chemical solution-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 12 minutes to introduce a cation group into the cellulose in the pulp to obtain a cation group-introduced pulp.

Next, the obtained cation group-introduced pulp was washed. The washing treatment was carried out by repeating the operation of pouring ion-exchanged water into the obtained cation-introduced pulp, stirring the pulp dispersion liquid so that the pulp was uniformly dispersed, and then filtering and dehydrating the pulp. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

Next, the washed cation group-introduced pulp was neutralized as follows. First, the washed cation-introduced pulp was diluted with 10 L of ion-exchanged water, and then 1N hydrochloric acid was added little by little with stirring to obtain a cation-introduced pulp slurry having a pH of 1 or more and 2 or less. Next, the cation-introduced pulp slurry was dehydrated and washed to obtain a cation-introduced pulp that had been neutralized. Then, ion-exchanged water was added to the obtained cation group-introduced pulp to prepare a dispersion liquid having a concentration of 0.5% by mass, and the neutralization treatment of the cellulose fibers was completed.

The obtained cation group-introduced pulp was subjected to trace nitrogen analysis, and the amount of cation group was calculated by the following formula. As a result, it was 1.45 mmol / g. In addition, when the cation group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.
(Amount of cation group) [mmol / g] = (Amount of nitrogen) / 14 × 1000 / (Amount of pulp with cation group introduced)

<Manufacturing example A4>
Ion-exchanged water is added to the phosphorylated pulp obtained in Production Example A1 and treated as a 1% by mass dispersion with a high-pressure homogenizer (Beryu-Mini, manufactured by Bigrain Co., Ltd.) 6 times at a pressure of 240 MPa. Was done. The bubbling suppression mechanism described above was not installed in this device. In this way, a pretreated fine fibrous cellulose dispersion having a concentration of 1% by mass was obtained. After casting the obtained fine fibrous cellulose dispersion, when observed with a transmission electron microscope, fine fibrous cellulose having a width of 3-4 nm was observed. No cellulose fibers having a width of 1 μm or more were observed.

<Example 1-1>
As the nanocarbon precursor, MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated and granulated) was used. By directly adding the nanocarbon precursor to the 0.5% by mass of the cellulose fiber dispersion obtained in Production Example A1, the concentration of the cellulose fiber becomes 0.5% by mass and the concentration of the nanocarbon precursor becomes 1% by mass. Prepared to be. The obtained mixed dispersion was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) three times at a pressure of 100 MPa. The bubbling suppression mechanism described above was installed in this device. After the high-pressure homogenizer treatment, a dispersion containing fine fibrous cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel. The dispersibility and TI value of this dispersion were evaluated by the method described later.

<Example 1-2>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-1 except that the cellulose fiber dispersion obtained in Production Example A2 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-3>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-1, except that the flake graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. The obtained dispersion was in the form of a glossy gel.

<Example 1-4>
As the nanocarbon precursor, both MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated to be granular) and phosphocyclic graphite Z-5F manufactured by Ito Graphite Co., Ltd. are used, and their respective concentrations are used. A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-1, except that the amount was adjusted to 0.5% by mass (total concentration was 1% by mass). The obtained dispersion was in the form of a glossy gel.

<Example 1-5>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example A3 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-6>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example B1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-7>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example C1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-8>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example D1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-9>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example E1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-10>
As the cellulose fiber dispersion liquid, a fine fibrous cellulose / nanocarbon dispersion liquid was obtained in the same manner as in Example 1-3 except that the one obtained in Production Example F1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-11>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example G1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-12>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Example 1-3 except that the cellulose fiber dispersion obtained in Production Example H1 was used. The obtained dispersion was in the form of a glossy gel.

<Example 1-13>
As the cellulose fiber dispersion liquid, a fine fibrous cellulose / nanocarbon dispersion liquid was obtained in the same manner as in Example 1-3 except that the one obtained in Production Example J1 was used. The obtained dispersion was in the form of a glossy gel.

<Comparative Examples 1 to 13>
Fine fibrous cellulose / nanocarbon dispersions were obtained in the same manner as in Examples 1-1 to 1-13, except that the dispersion treatment of the mixed dispersion with a high-pressure homogenizer was changed as follows. As a result of visually observing the obtained dispersions, the dispersed states were sparse.

(Distributed processing method in Comparative Examples 1 to 13)
The treatment was performed twice with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) at a pressure of 240 MPa. The processing was performed without providing a bubbling suppression mechanism in this device.

<Comparative Example 14>
The fine fibrous cellulose dispersion obtained in Production Example A4 and the nanocarbon dispersion obtained in Production Example a1 described later were mixed using an ultrasonic homogenizer (UP400S manufactured by Heelscher Co., Ltd.) to obtain fine fibrous cellulose. A nanocarbon dispersion was obtained. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a1>
LG Chem's MWCNT (LUCAN CP1001M, MWCNT aggregated and granulated) is 2% by mass as a nanocarbon precursor in ion-exchanged water, and a dispersant (thickener) for promoting suspension. ), Carboxymethyl cellulose (manufactured by Kanto Chemical Co., Inc., degree of polymerization of about 1050) was suspended so as to be 1% by mass. Then, the treatment was carried out 6 times at a pressure of 240 MPa with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.). The processing was performed without providing a bubbling suppression mechanism in this device. In this way, a nanocarbon dispersion having a concentration of 2% by mass (not including the solid content of the dispersant) was obtained.

<Comparative Example 15>
Fine fibrous cellulose / nanocarbon dispersion in the same manner as in Comparative Example 9, except that the nanocarbon dispersion obtained in Production Example a2, which will be described later, was used instead of the nanocarbon dispersion obtained in Production Example a1. Obtained liquid. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a2>
The same procedure as in Production Example a1 was carried out except that the flake graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. In this way, a nanocarbon dispersion having a concentration of 2% by mass (not including the solid content of the dispersant) was obtained.

<Comparative Example 16>
Fine fibrous cellulose / nanocarbon dispersion in the same manner as in Comparative Example 9 except that the nanocarbon dispersion obtained in Production Example a3 described later was used instead of the nanocarbon dispersion obtained in Production Example a1. Obtained liquid. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a3>
As the nanocarbon precursor, both LG Chem's MWCNT (LUCAN CP1001M and MWCNT are aggregated to form granules) and Ito Graphite's phosphonic graphite Z-5F are used, and their respective concentrations are used. Was prepared to be 1% by mass (total concentration was 2%), and was used in the same manner as in Production Example a1. In this way, a nanocarbon dispersion having a concentration of 2% by mass (not including the solid content of the dispersant) was obtained.

<Comparative example 17>
As the nanocarbon precursor, MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated and granulated) was used. The nanocarbon precursor was directly added to the 1% by mass cellulose fiber dispersion obtained in Production Example A4, and then ion-exchanged water was further added to bring the cellulose fiber concentration to 0.5% by mass and the nanocarbon precursor. It was adjusted so that the body concentration was 1% by mass. The obtained mixed dispersion was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) three times at a pressure of 100 MPa. The bubbling suppression mechanism described above was installed in this device. After the high-pressure homogenizer treatment, a fine fibrous cellulose / nanocarbon dispersion was obtained. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 18>
A fine fibrous cellulose nanocarbon dispersion was obtained in the same manner as in Comparative Example 17 except that phosphocyclic graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 19>
As the nanocarbon precursor, both MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated to be granular) and phosphocyclic graphite Z-5F manufactured by Ito Graphite Co., Ltd. are used, and their respective concentrations are used. A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Comparative Example 17 except that the one prepared to have a value of 0.5% by mass (total concentration was 1% by mass) was used. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 20>
As the cellulose fiber, the same as in Example 1-1 except that the softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 0.5% by mass was used. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Comparative Example 21>
As the cellulose fiber, the same as in Example 1-3 except that the softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 0.5% by mass was used. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Comparative Example 22>
As the cellulose fiber, the same as in Example 1-4 except that the softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 0.5% by mass was used. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Manufacturing example A11>
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

Next, the phosphorylated pulp after washing was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated and washed to obtain a phosphorylated pulp (cellulose fiber) subjected to a neutralization treatment.

<Manufacturing examples A12 to A17>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example A11 to obtain a dispersion having the concentration (concentration C [mass%]) shown in the table below. The relationship between the production example numbers and the concentration C is as shown in the table below.

The dispersion having a concentration of C [mass%] in each production example was treated once with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) at a pressure of 100 MPa. This device is equipped with a bubbling suppression mechanism. The high-pressure homogenizer includes a jet flow generator provided with a diamond nozzle and a bubbling suppression mechanism located downstream of the jet flow generator. In this device, a coolable pipe (cloak) was adopted as a bubbling suppression mechanism, and such a pipe (cloak) was arranged so as to cover the inner pipe through which the dispersion liquid flows. The length of the coolable pipe was 350 mm, and the coolable pipe was installed on the downstream side of the diamond nozzle 100 mm of the jet flow generating portion. In this bubbling suppression mechanism, while applying back pressure to the jet flow generated by the diamond nozzle, cooling water at 15 ° C. was flowed through the mantle at a flow rate of 27 L / min. In this way, a pretreated cellulose fiber dispersion having a concentration of C [mass%] was obtained. When the cellulose fiber dispersions obtained in Production Examples A12 to A17 were observed with an optical microscope, a large number of cellulose fibers having a width of 20 μm or more were observed in all of the production examples.

<Manufacturing example A18>
In the neutralization treatment, the same procedure as in Production Example A11 was carried out except that tetrabutylammonium hydroxide having a concentration of 40% by mass was used instead of sodium hydroxide to obtain cellulose fibers. Cellulose fibers had tetrabutylammonium ions (TBA ⁺ ) as counterions.

<Manufacturing example B11>
The same procedure as in Production Example A11 was carried out except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate to obtain phosphorous oxide pulp. Others were operated in the same manner as in Production Example A11 to obtain a cellulose fiber dispersion liquid.

<Manufacturing example C11>
38 parts by mass of amide sulfuric acid (sulfamic acid) was used instead of ammonium dihydrogen phosphate, and the same procedure as in Production Example A11 was carried out except that the heating time was extended to 19 minutes to obtain sulfated pulp. Others were operated in the same manner as in Production Example A11 to obtain a cellulose fiber dispersion liquid.

<Manufacturing example D11>
As the raw material pulp, softwood kraft pulp (undried) made by Oji Paper was used. Alkaline TEMPO oxidation treatment was carried out on this raw material pulp as follows.

Next, the obtained top-oxidized TEMPO oxide pulp was washed. The washing treatment is carried out by dehydrating the pulp slurry after the additional oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtering and dehydrating. rice field. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set. In this way, TEMPO oxidized pulp (cellulose fiber) was obtained.

<Manufacturing example E11>
[Oxidation of hypochlorous acid]
A sheet (solid content concentration 90% by mass) made from softwood bleached kraft pulp (NBKP) is treated with a hand mixer (Osaka Chemical Co., Ltd., Lab Miller PLUS) at a rotation speed of 20000 rpm for 15 seconds to form a cotton-like fluffing. It was made into pulp (solid content concentration 90% by mass). Next, sodium hypochlorite pentahydrate was added to ion-exchanged water to prepare an aqueous solution having a solid content concentration of sodium hypochlorite of 22% by mass. To 100 parts by mass of cotton-like fluffing pulp, 9000 parts by mass of a 22% by mass sodium hypochlorite aqueous solution was added and reacted in a warm bath at 30 ° C. for 2 hours to obtain a carboxy group-introduced pulp. During the reaction, a 1N aqueous sodium hydroxide solution was appropriately added to maintain the pH at 11.

<Manufacturing example F11>
[Maleic acid esterification]
A sheet (solid content concentration 90% by mass) made from softwood bleached kraft pulp (NBKP) is treated with a hand mixer (Osaka Chemical Co., Ltd., Lab Miller PLUS) at a rotation speed of 20000 rpm for 15 seconds to form a cotton-like fluffing. It was made into pulp (solid content concentration 90% by mass). The autoclave was filled with 100 parts by mass of cotton-like fluffing pulp and 50 parts by mass of maleic anhydride, and treated at 150 ° C. for 2 hours to obtain a carboxy group-introduced pulp.

The infrared absorption spectrum of the obtained pulp was measured using FT-IR. As a result, absorption based on the carboxy group was observed near 1580 and 1720 cm- ¹ , and it was confirmed that the maleic acid was esterified. Regarding the obtained carboxy group-introduced pulp, the amount of carboxy group measured by the measuring method described later was 1.22 mmol / g. Further, when the carboxy group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example G11>
[Carboxyethylation]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

<Manufacturing example H11>
[Sulfothethylation]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

With respect to the obtained sulfoethyl group-introduced pulp, the amount of sulfoethyl group (sulfone group amount) measured by the measuring method described later was 1.48 mmol / g. Further, when the sulfoethyl group-introduced pulp was tested and analyzed by an X-ray diffractometer, it was typical at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. Peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Manufacturing example J11>
[Cationation treatment]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml).

Next, the washed cation group-introduced pulp was neutralized as follows. First, the washed cation-introduced pulp was diluted with 10 L of ion-exchanged water, and then 1N of hydrochloric acid was added little by little with stirring to obtain a cation-introduced pulp slurry having a pH of 1 or more and 2 or less. Next, the cation-introduced pulp slurry was dehydrated and washed to obtain a cation-introduced pulp that had been neutralized. Then, ion-exchanged water was added to the obtained cation group-introduced pulp to prepare a dispersion liquid having a concentration of 0.5% by mass, and the neutralization treatment of the cellulose fibers was completed.

<Manufacturing example A19>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example A11, and treated as a dispersion with a concentration of 4% by mass with a high-pressure homogenizer (Beryu-Mini, manufactured by Bigrain Co., Ltd.) 6 times at a pressure of 240 MPa. Was done. As in the case of the device described in Production Example A12, the device was not equipped with the bubbling suppression mechanism as described above. In this way, a pretreated fine fibrous cellulose dispersion having a concentration of 4% by mass was obtained. After casting the obtained fine fibrous cellulose dispersion, when observed with a transmission electron microscope, fine fibrous cellulose having a width of 3-4 nm was observed. No cellulose fibers having a width of 1 μm or more were observed.

<Example 101-1>
As the nanocarbon precursor, MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated and granulated) was used. Ion-exchanged water and a nanocarbon precursor were directly added to the cellulose fibers obtained in Production Example A11 to prepare the cellulose fibers so that the concentration of the cellulose fibers was 1% by mass and the concentration of the nanocarbon precursors was 1% by mass. The obtained mixed dispersion was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) three times at a pressure of 100 MPa. The bubbling suppression mechanism described above in Production Example A12 was provided in this device. After the high-pressure homogenizer treatment, a dispersion containing fine fibrous cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel. The particle dispersibility of this dispersion, the standard deviation of the mass after combustion, and the uniform dispersibility were evaluated by the method described later.

<Example 101-2>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-1 except that the concentration of cellulose fibers in the mixed dispersion was 1.5% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-3>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-1 except that the concentration of cellulose fibers in the mixed dispersion was set to 2% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-4>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-1 except that the concentration of cellulose fibers in the mixed dispersion was set to 4% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-5>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-1 except that the concentration of cellulose fibers in the mixed dispersion was 6% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-6>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-1 except that the concentration of cellulose fibers in the mixed dispersion was set to 10% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-7>
The cellulose fiber dispersion obtained in Production Example A12 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-1 except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-8>
The cellulose fiber dispersion obtained in Production Example A13 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-2 except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-9>
The cellulose fiber dispersion obtained in Production Example A14 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-3 except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-10>
The cellulose fiber dispersion obtained in Production Example A15 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-4 except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-11>
The cellulose fiber dispersion obtained in Production Example A16 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-5, except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-12>
The cellulose fiber dispersion obtained in Production Example A17 was used instead of the cellulose fiber obtained in Production Example A11, and was in the form of fine fibers in the same manner as in Example 101-6 except that ion-exchanged water was not added. A dispersion containing cellulose / nanocarbon was obtained. The obtained dispersion was in the form of a glossy gel.

<Example 101-13>
A dispersion containing fine fibrous cellulose nanocarbon was obtained in the same manner as in Example 101-9, except that the concentration of the nanocarbon precursor in the mixed dispersion was adjusted to 2% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-14>
A dispersion containing fine fibrous cellulose nanocarbon was obtained in the same manner as in Example 101-9, except that the concentration of the nanocarbon precursor in the mixed dispersion was adjusted to 4% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-15>
A dispersion containing fine fibrous cellulose nanocarbon was obtained in the same manner as in Example 101-9, except that the concentration of the nanocarbon precursor in the mixed dispersion was adjusted to 6% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-16>
A dispersion containing fine fibrous cellulose nanocarbon was obtained in the same manner as in Example 101-9, except that the concentration of the nanocarbon precursor in the mixed dispersion was adjusted to 10% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-17>
A dispersion containing fine fibrous cellulose nanocarbon was obtained in the same manner as in Example 101-11, except that the concentration of the nanocarbon precursor in the mixed dispersion was adjusted to 6% by mass. The obtained dispersion was in the form of a glossy gel.

<Example 101-18>
As the nanocarbon precursor, MWCNT manufactured by LG Chem (LUCAN CP1001M, MWCNT is aggregated and granulated) was used, except that the concentration of the nanocarbon precursor in the mixed dispersion was set to 2% by mass. , A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-3. The obtained dispersion was in the form of a glossy gel.

<Example 101-19>
A mixed dispersion using both LG Chem's MWCNT (LUCAN CP1001M and MWCNT aggregated to form granules) and Ito Graphite's Phosphorus Graphite Z-5F as nanocarbon precursors. A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Examples 101-18, except that the respective concentrations in the medium were adjusted to 1% by mass (total concentration was 2% by mass). .. The obtained dispersion was in the form of a glossy gel.

<Example 101-20>
The cellulose fiber obtained in Production Example A18 was used, and the flake graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor, and the concentration of the nanocarbon precursor in the mixed dispersion was reduced to 2% by mass. A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-3. The obtained dispersion was in the form of a glossy gel.

<Example 101-21>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fiber obtained in Production Example B11 was used. The obtained dispersion was in the form of a glossy gel.

<Example 101-22>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fiber obtained in Production Example C11 was used. The obtained dispersion was in the form of a glossy gel.

<Example 101-23>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fiber obtained in Production Example D11 was used. The obtained dispersion was in the form of a glossy gel.

<Example 101-24>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fibers obtained in Production Example E11 were used. The obtained dispersion was in the form of a glossy gel.

<Example 101-25>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fiber obtained in Production Example F11 was used. The obtained dispersion was in the form of a glossy gel.

<Example 101-26>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fibers obtained in Production Example G11 were used. The obtained dispersion was in the form of a glossy gel.

<Example 101-27>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fibers obtained in Production Example H11 were used. The obtained dispersion was in the form of a glossy gel.

<Example 101-28>
A dispersion containing fine fibrous cellulose / nanocarbon was obtained in the same manner as in Example 101-20, except that the cellulose fibers obtained in Production Example J11 were used. The obtained dispersion was in the form of a glossy gel.

<Comparative Example 101>
LG Chem's MWCNT (LUCAN CP1001M, MWCNT aggregated and granulated) is 2% by mass as a nanocarbon precursor in ion-exchanged water, and a dispersant (thickener) for promoting suspension. ), Carboxymethyl cellulose (manufactured by Kanto Chemical Co., Inc., degree of polymerization of about 1050) was suspended so as to be 2% by mass. The obtained mixed dispersion was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) three times at a pressure of 100 MPa. The bubbling suppression mechanism described above in Production Example A12 was provided in this device. After the high-pressure homogenizer treatment, a dispersion containing carboxymethyl cellulose / nanocarbon was obtained. The obtained dispersion was easy to flow, and no strong luster was observed.

<Comparative Example 102>
A dispersion containing carboxymethyl cellulose / nanocarbon was obtained in the same manner as in Comparative Example 101 except that phosphotic graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. The obtained dispersion was easy to flow, and no strong luster was observed.

<Comparative Example 103>
A mixed dispersion using both LG Chem's MWCNT (LUCAN CP1001M and MWCNT aggregated to form granules) and Ito Graphite's Phosphorus Graphite Z-5F as nanocarbon precursors. A dispersion containing carboxymethyl cellulose / nanocarbon was obtained in the same manner as in Comparative Example 101 except that the respective concentrations in the medium were adjusted to 1% by mass (total concentration was 2% by mass). The obtained dispersion was easy to flow, and no strong luster was observed.

<Comparative Example 104>
The fine fibrous cellulose dispersion obtained in Production Example A19 and the nanocarbon dispersion obtained in Production Example a11 described later are mixed using an ultrasonic homogenizer (UP400S manufactured by Heelscher Co., Ltd.), and the fine fibrous cellulose is mixed. -A nanocarbon dispersion was obtained. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a11>
In ion-exchanged water, LG Chem's MWCNT (LUCAN CP1001M, MWCNT aggregated and granulated) was 4% by mass as a nanocarbon precursor, and a dispersant (thickener) for promoting suspension. ), Carboxymethyl cellulose (manufactured by Kanto Chemical Co., Inc., degree of polymerization of about 1050) was suspended so as to be 1% by mass. Then, the treatment was carried out 6 times at a pressure of 240 MPa with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.). The processing was performed without providing a bubbling suppression mechanism in this device. In this way, a nanocarbon dispersion having a concentration of 4% by mass (not including the solid content of the dispersant) was obtained.

<Comparative Example 105>
Fine fibrous cellulose / nanocarbon dispersion in the same manner as in Comparative Example 104, except that the nanocarbon dispersion obtained in Production Example a12, which will be described later, was used instead of the nanocarbon dispersion obtained in Production Example a11. Obtained liquid. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a12>
The same procedure as in Production Example a11 was carried out except that the flake graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. In this way, a nanocarbon dispersion having a concentration of 4% by mass (not including the solid content of the dispersant) was obtained.

<Comparative Example 106>
Fine fibrous cellulose / nanocarbon dispersion in the same manner as in Comparative Example 104, except that the nanocarbon dispersion obtained in Production Example a13, which will be described later, was used instead of the nanocarbon dispersion obtained in Production Example a11. Obtained liquid. As a result of visually observing the obtained dispersion liquid, the dispersion state was sparse.

<Manufacturing example a13>
As the nanocarbon precursor, both MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated to be granular) and phosphonic graphite Z-5F manufactured by Ito Graphite Co., Ltd. are used, and their respective concentrations are used. Was prepared to be 2% by mass (total concentration was 4% by mass), and was used in the same manner as in Production Example a11. In this way, a nanocarbon dispersion having a concentration of 4% by mass (not including the solid content of the dispersant) was obtained.

<Comparative Example 107>
As the nanocarbon precursor, MWCNT manufactured by LG Chem (LUCAN CP1001M and MWCNT are aggregated and granulated) was used. After adding the nanocarbon precursor directly to the 4% by mass concentration of fine fibrous cellulose dispersion obtained in Production Example A19, ion-exchanged water was further added to make the fine fibrous cellulose concentration 2% by mass, nano. The concentration of the carbon precursor was adjusted to 2% by mass. The obtained mixed dispersion was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) three times at a pressure of 100 MPa. The bubbling suppression mechanism described above in Production Example A12 was provided in this device. After the high-pressure homogenizer treatment, a fine fibrous cellulose / nanocarbon dispersion was obtained. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 108>
A fine fibrous cellulose / nanocarbon dispersion was obtained in the same manner as in Comparative Example 107, except that the flake graphite Z-5F manufactured by Ito Graphite Co., Ltd. was used as the nanocarbon precursor. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 109>
A mixed dispersion using both LG Chem's MWCNT (LUCAN CP1001M and MWCNT aggregated to form granules) and Ito Graphite's Phosphorus Graphite Z-5F as nanocarbon precursors. In the same manner as in Comparative Example 107, a fine fibrous cellulose / nanocarbon dispersion was obtained, except that those prepared so that the respective concentrations were 1% by mass (total concentration was 2% by mass) were used. As a result of visually observing the obtained dispersion liquid, the dispersion state was somewhat sparse.

<Comparative Example 110>
As the cellulose fiber, a softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 2% by mass, and the same as in Comparative Example 101. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Comparative Example 111>
As the cellulose fiber, the same as in Comparative Example 102 except that the softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 2% by mass. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Comparative Example 112>
As the cellulose fiber, the same as in Comparative Example 103 except that the softwood kraft pulp (undried) made by Oji Paper was diluted with ion-exchanged water to a concentration of 2% by mass. Due to the blockage of the high-pressure homogenizer, a fine fibrous cellulose / nanocarbon dispersion could not be obtained.

<Measurement and evaluation>
With respect to the cellulose fibers or fine fibrous cellulose fibers obtained in Production Examples A1 to A4, B1, C1, D1, E1, F1, G1, H1 and J1, the supernatant yield and the amount of substituents were measured by the method described later. Further, the fine fibrous cellulose / nanocarbon dispersions obtained in Examples 1-1 to 1-13 and Comparative Examples 1 to 19 were evaluated for particle dispersibility and thixotropy by the method described later. In Comparative Examples 20 to 22, fine fibrous cellulose / nanocarbon dispersion was not obtained.

In Examples 1-1 to 1-13 and Comparative Examples 1 to 19, the obtained dispersion was cast-dried and the obtained sample was observed with an electron microscope to obtain fine fibers having a fiber width of 20 nm or less. The presence of fibrous cellulose and nanocarbon having at least one of the length, width, and thickness of 1000 nm or less was confirmed.

For the cellulose fibers or fine fibrous celluloses obtained in Production Examples A11 to A19, B11, C11, D11, E11, F11, G11, H11 and J11, the supernatant yield and the amount of substituents were measured by the method described later. Further, with respect to the fine fibrous cellulose / nanocarbon dispersions obtained in Examples 101-1 to 101-28 and Comparative Examples 101 to 109, the particle dispersibility and the standard deviation of the mass after combustion were evaluated by the method described later. .. For Comparative Examples 110 to 112, fine fibrous cellulose / nanocarbon dispersions could not be obtained.

In Examples 101-1 to 101-28 and Comparative Examples 101 to 109, the obtained dispersion was cast-dried and the obtained sample was observed with an electron microscope to obtain fine fibers having a fiber width of 20 nm or less. The presence of fibrous cellulose and nanocarbon having at least one of the length, width, and thickness of 1000 nm or less was confirmed.

[Measurement of phosphorus oxo acid group amount]
In measuring the amount of phosphorous acid groups (amount of phosphorous acid groups or amount of phosphorous acid groups) of cellulose fibers, first, ion-exchanged water is added to the target cellulose fibers, and a slurry having a solid content concentration of 0.2% by mass is added. Was prepared. This slurry was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated with an ion exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) having a volume of 1/10 was added to the fine fibrous cellulose dispersion, and the mixture was shaken for 1 hour. After that, it was poured on a mesh having a mesh size of 90 μm to separate the resin and the slurry.
In the titration using alkali, the pH value indicated by the slurry is changed while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose dispersion treated with the ion exchange resin every 5 seconds. Was performed by measuring. The titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 2). The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated was defined as the amount of phosphorus oxo acid groups (mmol / g).

[Measurement of carboxy group amount]
In the measurement of the carboxy group amount of the cellulose fiber, first, ion-exchanged water was added to the target cellulose fiber to prepare a slurry having a solid content concentration of 0.2% by mass. This slurry was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated with an ion exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) having a volume of 1/10 was added to the fine fibrous cellulose dispersion, and the mixture was shaken for 1 hour. After that, it was poured on a mesh having a mesh size of 90 μm to separate the resin and the slurry.
For titration using alkali, a 0.1 N sodium hydroxide aqueous solution is added to the fine fibrous cellulose dispersion treated with an ion exchange resin once every 30 seconds by 50 μL, and the pH indicated by the dispersion is adjusted. This was done by measuring the change in value. The amount of carboxy group (mmol / g) is obtained by dividing the amount of alkali (mmol) required in the region corresponding to the first region shown in FIG. 3 of the measurement results by the solid content (g) in the slurry to be titrated. Calculated.

[Measurement of sulfate ester group amount and sulfone group amount]
The amount of sulfate ester group and the amount of sulfone group of the cellulose fiber were measured as follows. The cellulose fibers obtained in Production Examples C1, H1, C11 and H11 were frozen in a freezer and then dried in a freeze-dryer (FreeZone manufactured by Loveconco) for 3 days. The obtained freeze-dried product was pulverized using a hand mixer (manufactured by Osaka Chemical Co., Ltd., Lab Miller PLUS) at a rotation speed of 20,000 rpm for 60 seconds to obtain a powder.
The sample after freeze-drying and pulverization was decomposed by heating under pressure using nitric acid in a closed container. Then, it was diluted appropriately and the amount of sulfur was measured by ICP-OES. The values calculated by dividing by the absolute dry mass of the fine fibrous cellulose tested were taken as the amount of sulfate ester groups and the amount of sulfone groups (unit: mmol / g) of the fine fibrous cellulose.

<Measurement of supernatant yield after centrifugation of cellulose fibers and fine fibrous cellulose dispersion>
The yield of the supernatant after centrifuging the cellulose fiber or the fine fibrous cellulose dispersion was measured by the method described below. The supernatant yield after centrifugation is an index of the yield of fine fibrous cellulose, and if the supernatant yield exceeds 90%, substantially all of the cellulose fibers become fine fibrous cellulose having a width of 1000 nm or less. ing. On the other hand, when the supernatant yield is less than 70%, it contains a considerable amount of cellulose fibers that have not been refined yet.
When measuring the supernatant yield, a cellulose fiber or fine fibrous cellulose dispersion was prepared to have a solid content concentration of 0.2% by mass, and a cooling high-speed centrifuge (Kokusan Co., Ltd., H-2000B) was used to prepare 12000 G. Centrifugation was performed under the condition of 10 minutes. The obtained supernatant was collected, and the solid content concentration of the supernatant was measured. The supernatant yield was determined based on the following formula.
Supernatant yield (%) = Solid content concentration of supernatant liquid (mass%) /0.2 × 100

<Particle dispersibility of fine fibrous cellulose / nanocarbon dispersion>
The particle dispersibility of the fine fibrous cellulose / nanocarbon dispersions obtained in Examples and Comparative Examples was evaluated according to the following criteria. The higher the particle dispersibility, the more highly the cellulose fibers and carbon particles are nano-sized and uniformly dispersed. Specifically, 1 volume% of glass beads (BZ-1 manufactured by AS ONE) are added to a fine fibrous cellulose / nanocarbon dispersion having a total dry solid content concentration of 0.2% by mass, and visually observed. The results were evaluated as follows.
A: No settling of glass beads B: A small amount of glass beads settles C: The entire amount of glass beads settles

<Thixotropy (TI value) of fine fibrous cellulose / nanocarbon dispersion>
The thixotropy (TI value) of the fine fibrous cellulose / nanocarbon dispersions obtained in Examples and Comparative Examples was evaluated. The higher the TI value and the higher the thixotropy, the higher the degree of nano-sized cellulose fibers and carbon particles, and the more uniformly dispersed, and the less damage the obtained fine fibrous cellulose and nanocarbon particles are. become.
When calculating the TI value of the fine fibrous cellulose / nanocarbon dispersion, the concentration of the fine fibrous cellulose / nanocarbon dispersion is appropriately diluted with ion-exchanged water to obtain the viscosity measured under the conditions described below. It was set to 1000 cps. Using a dispersion having the same concentration, the viscosity η was measured at 23 ° C. and a rotation speed of 60 rpm under the conditions described below. Then, a value of 1000 / η (TI value) was calculated and classified according to the following criteria.
A: TI value is 5 or more B: TI value is 2 or more and less than 5 C: TI value is less than 2

<Viscosity measurement of fine fibrous cellulose / nanocarbon dispersion>
The viscosity of the fine fibrous cellulose / nanocarbon dispersion was measured as follows. First, the fine fibrous cellulose / nanocarbon dispersion was diluted so that the B-type viscosity of the fine fibrous cellulose / nanocarbon dispersion was 1000 cps. After dilution, the mixture was stirred with a disperser at 1500 rpm for 5 minutes. Next, the viscosity of the obtained slurry was measured using a B-type viscometer (analog viscometer T-LVT manufactured by BLOOKFIELD). The measurement conditions were a rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement was defined as the viscosity (initial viscosity) of the slurry. The slurry to be measured was allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours before the measurement. The liquid temperature of the slurry at the time of measurement was 23 ° C.

<Uniform dispersibility>
The fine fibrous cellulose / nanocarbon dispersions obtained in Examples and Comparative Examples were visually observed and the dispersibility was evaluated according to the following criteria.
A: One liquid with continuous dispersibility, where only fine fibrous cellulose dispersion exists and no place where only nanocarbon dispersion exists B: One liquid with continuous dispersibility, but fine The location where only the fibrous cellulose dispersion is present and the location where only the nanocarbon dispersion is present are sparsely present. C: The dispersion is separated into multiple parts, and the location where only the fine fibrous cellulose dispersion is present and the nano There are sparsely populated areas where only the carbon dispersion is present.

<Standard deviation of mass ratio after combustion>
The standard deviation of the mass ratio after combustion was measured using a differential thermogravimetric simultaneous measuring device (TG / DTA6300 manufactured by Seiko Instruments Co., Ltd. (currently Hitachi High-Tech Science Co., Ltd.)). Specifically, 1 cc of a sample randomly separated from the obtained fine fibrous cellulose / nanocarbon dispersion was heated in a nitrogen atmosphere according to the following temperature program, and the weight was measured once per second. .. Calculate the ratio of weight when reaching 600 ° C (ratio of mass after combustion) to the weight at 110 ° C, obtain the standard deviation of the mass ratio after combustion when measured 10 times, and evaluate as follows. did.
<Temperature program>
Hold at 1.50 ° C for 5 minutes Increase temperature from 2.50 ° C to 100 ° C (heating rate: 10 ° C / min)
3. Hold at 100 ° C for 10 minutes 4. Raise the temperature from 100 ° C to 600 ° C (heating rate: 10 ° C / min)
<Evaluation criteria>
A: The value obtained by dividing the standard deviation by the average value (CV value) is less than 10% B: The value obtained by dividing the standard deviation by the average value (CV value) is 10% or more and less than 20% C: The standard deviation The value divided by the average value (CV value) is 20% or more. The mass ratio of the fine fibrous cellulose / nanocarbon-containing material after combustion is the value obtained by dividing the following α by β (value of α / β). Yes, the CV value is a value obtained by performing measurement 10 times to calculate the value of α / β and dividing the standard deviation of the value of α / β by the average value of the values of α / β.
α: Mass after combustion of fine fibrous cellulose / nanocarbon-containing material (mass when reaching 600 ° C)
β: Absolute dry mass of fine fibrous cellulose / nanocarbon-containing material (mass when reaching 110 ° C)

In the examples, a fine fibrous cellulose / nanocarbon-containing material having excellent particle dispersibility was obtained.
Further, when the fine fibrous cellulose / nanocarbon-containing material (dispersion liquid) obtained in the examples was applied to a base material and dried, the dispersion liquid was dried in a short time to obtain a sheet with less segregation.

<Preparation of fine fibrous cellulose / nanocarbon-containing ink>
<Example 2-1>
The fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 was packed in a 10 mL syringe, and the injection speed from the syringe was 1 mL per second, 20 mm per second. It was extruded linearly onto the polypropylene substrate at the moving speed of. After extrusion, the straight line formed by the dispersion liquid tilted the base material at 45 ° while maintaining a horizontal state with the floor surface. The dispersion liquid adhered to the substrate without dripping. Moreover, when the dispersion liquid was dried, it adhered to the substrate as it was. Therefore, the dispersion can be used as an ink. In addition, it was confirmed that the line from which the ink was dried has conductivity. Therefore, the dispersion can also be used as a conductive ink.

<Example 2-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. The suitability as an ink was confirmed in the same manner as in Example 2-1 except that the fiber) / nanocarbon (grafene) dispersion was used. As a result, the dispersion liquid adhered to the base material without dripping. Moreover, when the dispersion liquid was dried, it adhered to the substrate as it was. Therefore, the dispersion can be used as an ink. In addition, it was confirmed that the line from which the ink was dried has conductivity. Therefore, the dispersion can also be used as a conductive ink.

<Preparation of rubber containing fine fibrous cellulose / nanocarbon>
<Example 3-1>
Natural rubber latex (trade name: "Experimental reagent latex liquid natural rubber" is added to the fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18. , Made by KENIS, Ltd.) and mixed with a high-speed rotating disperser. The total mass of the fine fibrous cellulose and the nanocarbon was 5 parts by mass with respect to 100 parts by mass of the rubber component. The obtained mixed solution was cast on a tea tray, dried at 23 ° C. and a relative humidity of 50% for 1 week, and then heat-treated at 105 ° C. for 15 minutes to obtain a rubber sheet containing fine fibrous cellulose / nanocarbon. Was done. The obtained rubber sheet was a sheet in which fine fibrous cellulose and nanocarbon were uniformly dispersed in the rubber, or those in which fine fibrous cellulose and nanocarbon were bonded to each other were uniformly dispersed in the rubber.

<Example 3-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. The suitability as a rubber composite material was confirmed in the same manner as in Example 3-1 except that the fiber) / nanocarbon (grafene) dispersion was used. The obtained rubber sheet was a sheet in which fine fibrous cellulose and nanocarbon were uniformly dispersed in the rubber, or those in which fine fibrous cellulose and nanocarbon were bonded to each other were uniformly dispersed in the rubber.

<Preparation of fine fibrous cellulose / nanocarbon-containing resin>
<Example 4-1>
<Dissolution of polyvinyl alcohol>
Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval 105, degree of polymerization: 500, degree of saponification: 98 to 99 mol%) was added to ion-exchanged water so as to have a concentration of 20% by mass, and the mixture was stirred at 95 ° C. for 1 hour to dissolve.

<Sheet>
A polyvinyl alcohol solution is added to the fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 to obtain fine fibrous cellulose and nanocarbon. The amount of polyvinyl alcohol was adjusted to 100 parts by mass with respect to 100 parts by mass of the total mass. Next, the concentration was adjusted so that the total solid content concentration was 0.6% by mass. The suspension was weighed so that the finished basis weight of the sheet was 45 g / m ² , developed on a commercially available acrylic plate, and dried in a dryer at 70 ° C. for 24 hours. A dammed plate was placed on the acrylic plate so as to have a predetermined basis weight. A sheet was obtained by the above procedure, and its thickness was 30 μm. The obtained sheet was a sheet in which fine fibrous cellulose and nanocarbon were uniformly dispersed in the resin, respectively, or those in which fine fibrous cellulose and nanocarbon were bonded to each other without unevenness.

<Example 4-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. The suitability as a resin composite material was confirmed in the same manner as in Example 4-1 except that a fiber) / nanocarbon (grafene) dispersion was used. The obtained sheet was a sheet in which fine fibrous cellulose and nanocarbon were uniformly dispersed in the resin, respectively, or those in which fine fibrous cellulose and nanocarbon were bonded to each other without unevenness.

<Preparation of fine fibrous cellulose / nanocarbon-containing sheet>
<Example 5-1>
Ion-exchanged water is added to the fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18, and the total solid content concentration is 0.5. The concentration was adjusted to be mass%. The suspension was weighed so that the finished basis weight of the sheet was 45 g / m ² , developed on a commercially available acrylic plate, and dried in a dryer at 70 ° C. for 24 hours. A dammed plate was placed on the acrylic plate so as to have a predetermined basis weight. A sheet was obtained by the above procedure, and its thickness was 30 μm. The obtained sheet showed no unevenness, and fibers and particles did not come off even when squeezed by hand, and the sheet was stable.

<Example 5-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. A fine fibrous cellulose / nanocarbon-containing sheet was prepared in the same manner as in Example 5-1 except that the fiber) / nanocarbon (graphene) dispersion was used. By this procedure, a sheet was obtained, the thickness of which was 30 μm. The obtained sheet showed no unevenness, and fibers and particles did not come off even when squeezed by hand, and the sheet was stable.

<Preparation of plate-like body containing fine fibrous cellulose / nanocarbon>
<Example 6-1>
Papermaking pulp (Oji Paper, coniferous kraft pulp) was added to the fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18. The pulp for papermaking was prepared to be 400 parts by mass with respect to the total mass of 100 parts by mass of the fine fibrous cellulose and nanocarbon. 100 parts by mass of a 1% mass aluminum sulfate aqueous solution was added to the obtained mixed dispersion, and filtration was performed with a papermaking wire to obtain a pulp cake. The obtained cake was mechanically squeezed and then dried with a cylinder dryer set at 120 ° C. to obtain a plate-like body having a thickness of 1 mm. The obtained plate-like body was resistant to water and was suitable as a structure. Moreover, the obtained plate-like body showed conductivity.

<Preparation of plate-like body containing fine fibrous cellulose / nanocarbon>
<Example 6-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. When the same procedure as in Example 6-1 was carried out except that the fiber) / nanocarbon (graphene) dispersion was used, a fine fibrous cellulose / nanocarbon-containing plate-like body was obtained. The obtained plate-like body was resistant to water and was suitable as a structure. Moreover, the obtained plate-like body showed conductivity.

<Preparation of fine fibrous cellulose / nanocarbon-containing yarn>
<Example 7-1>
The fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 was injected into ethanol containing 10% by mass of aluminum chloride using a syringe. However, a linear gel-like body was obtained. This linear gel was pulled up from the solvent, dried in a dryer at 70 ° C. for 24 hours, washed with ion-exchanged water, further immersed in acetone, pulled up and air-dried. As a result, a yarn having a fiber diameter of 1 to 3 mm and not torn even when pulled by hand was obtained.

<Example 7-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. As a result of the same procedure as in Example 7-1 except that the fiber) / nanocarbon (grafene) dispersion was used, a thread having a fiber diameter of 1 to 3 mm and not torn even when pulled by hand was obtained.

<Electromagnetic wave blocking sheet>
<Example 8-1>
The fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 was centrifuged at a gravitational acceleration of 12000 G for 15 minutes. The supernatant of the obtained dispersion was cast to obtain a translucent fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) film. When a smartphone (communication with 4G radio waves) was sandwiched between the obtained films and the edges of the film were completely covered with aluminum foil, the smartphone showed out of service area. From the above, it was confirmed that the obtained fine fibrous cellulose / nanocarbon-containing film was an electromagnetic wave blocking sheet.

<Example 8-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. As a result of the same procedure as in Example 8-1 except that the fiber) / nanocarbon (graphene) dispersion was used, a translucent fine fibrous cellulose (cellulose nanofiber) / nanocarbon (graphene) film was obtained. When a smartphone (communication with 4G radio waves) was sandwiched between the obtained films and the edges of the film were completely covered with aluminum foil, the smartphone showed out of service area. From the above, it was confirmed that the obtained fine fibrous cellulose / nanocarbon-containing film was an electromagnetic wave blocking sheet.

<Electrode>
<Example 9-1>
The fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 was applied so that the thickness of the coating film after drying was 30 μm. .. Two sheets of this aluminum foil with a coating film were prepared, and a thin filter paper impregnated with a saturated saline solution containing 10% by mass of polyvinyl alcohol was prepared. A simple element was obtained by stacking aluminum foil, coating film, impregnated filter paper, coating film, and aluminum foil in this order without short-circuiting. The electrical resistance of this simple element was 10 Ω or less. We also confirmed that it can be charged by connecting it to a power source. Therefore, it was confirmed that the obtained simple element forms an electric double layer capacitor. It was also confirmed that this simple element can be easily wound up and becomes a winding type electric double layer capacitor. From the above, it was confirmed that the metal foil or the like coated with the fine fibrous cellulose / nanocarbon dispersion liquid of the present embodiment can be used as an electrode of a battery or a capacitor.

<Example 9-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. As a result of the same procedure as in Example 9-1 except that the fiber) / nanocarbon (graphene) dispersion was used, the electric resistance of the obtained simple element was 10 Ω or less. We also confirmed that it can be charged by connecting it to a power source. Therefore, it was confirmed that the obtained simple element forms an electric double layer capacitor. It was also confirmed that this simple element can be easily wound up and becomes a winding type electric double layer capacitor. From the above, it was confirmed that the metal foil or the like coated with the fine fibrous cellulose / nanocarbon dispersion liquid of the present embodiment can be used as an electrode of a battery or a capacitor.

<Preparation of fine fibrous cellulose / nanocarbon-containing concrete>
<Example 10-1>
The fine fibrous cellulose (cellulose nanofiber) / nanocarbon (carbon nanotube) dispersion obtained in Example 1-1 or Example 101-18 for curing instant cement (manufactured by Toyo Materan Co., Ltd.). Used in place of water. Specifically, 100 parts by mass of instant cement was mixed so that the amount of water contained in the dispersion of fine fibrous cellulose and nanocarbon was 15 parts by mass. After mixing, mortar was obtained by kneading, and the mortar was placed in a mold having a thickness of 2 cm and a length and width of 10 cm, and allowed to stand for 1 day to be cured. As a result, a concrete containing fine fibrous cellulose / nanocarbon was obtained. The obtained concrete was sufficiently hardened and had excellent strength. Moreover, the obtained concrete showed conductivity.

<Example 10-2>
Instead of the fine fibrous cellulose / nanocarbon dispersion obtained in Example 1-1 or Example 101-18, the fine fibrous cellulose (cellulose nano) obtained in Example 1-3 or Example 101-13. When the same procedure as in Example 10-1 was carried out except that the fiber) / nanocarbon (graphene) dispersion was used, a fine fibrous cellulose / nanocarbon-containing concrete was obtained. The obtained concrete was sufficiently hardened and had excellent strength. Moreover, the obtained concrete showed conductivity.

10 Jet flow generator 20 Bubbling suppression unit 100 Miniaturization processing device

Claims

A step of performing a miniaturization treatment on a mixed solution containing a cellulose fiber having an ionic substituent, a nanocarbon precursor, and a solvent is included.
A method for producing a fine fibrous cellulose / nanocarbon-containing material, in which bubbling is suppressed in the step of performing the micronization treatment.
The method for producing a fine fibrous cellulose / nanocarbon-containing product according to claim 1, wherein the content of the solvent in the mixed solution is 99% by mass or less with respect to the total mass of the mixed solution.
The method for producing a fine fibrous cellulose / nanocarbon-containing material according to claim 1 or 2, wherein in the step of performing the miniaturization treatment, the miniaturization treatment is performed using a high-pressure homogenizer.
The method for producing a fine fibrous cellulose / nanocarbon-containing material according to any one of claims 1 to 3, wherein bubbling is suppressed by cooling in the step of performing the micronization treatment.
The method for producing a fine fibrous cellulose / nanocarbon-containing product according to any one of claims 1 to 4, wherein the ionic substituent is an anionic group.
The method for producing a fine fibrous cellulose / nanocarbon-containing material according to any one of claims 1 to 5, wherein the ionic substituent is a phosphoric acid group or a substituent derived from a phosphoric acid group.
It contains fine fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent, and nanocarbon.
Fine fibrous cellulose / nanocarbon-containing material having a thixotropic index value (TI value) of 2 or more calculated under the following condition a;
(Condition a)
The fine fibrous cellulose / nanocarbon-containing material is dispersed in water to obtain a dispersion having a viscosity of 1000 cps measured at 23 ° C. with a B-type viscometer at a rotation speed of 3 rpm; 23 ° C. with a B-type viscometer. , The viscosity (η) of the dispersion measured at a rotation speed of 60 rpm is measured, and a value of 1000 / η is defined as a thixotropic index value (TI value) of the fine fibrous cellulose / nanocarbon-containing product.
The content of the solvent in the fine fibrous cellulose / nanocarbon-containing material is 99% by mass or less with respect to the total mass of the fine fibrous cellulose / nanocarbon-containing material.
The fine fibrous cellulose / nanocarbon-containing material according to claim 7, wherein the fine fibrous cellulose and the nanocarbon are uniformly dispersed in the fine fibrous cellulose / nanocarbon-containing material.
The fine fibrous cellulose / nanocarbon-containing product according to claim 7 or 8, wherein the ionic substituent is an anionic group.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 9, wherein the ionic substituent is a phosphoric acid group or a substituent derived from a phosphoric acid group.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 10, wherein the nanocarbon is at least one selected from the group consisting of carbon nanotubes and graphene.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 11, which is used for paints.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 11, which is used for a resin composition.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 11, which is used for concrete materials.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 11, which is used for a filamentous or plate-like structure.
The fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11, which is used for electromagnetic wave shielding.
The fine fibrous cellulose / nanocarbon-containing product according to any one of claims 7 to 11, which is used for an electrochemical device.
A paint containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
A resin composition containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
A concrete material containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
A filamentous or plate-like structure containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
An electromagnetic wave shield containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.
An electrochemical device containing the fine fibrous cellulose / nanocarbon-containing material according to any one of claims 7 to 11.