WO2022158498A1

WO2022158498A1 - Fine cellulose fiber–containing solvent, practical liquid, and practical liquid preparation method

Info

Publication number: WO2022158498A1
Application number: PCT/JP2022/001864
Authority: WO
Inventors: さくら森光; 朱十西村
Original assignee: 丸住製紙株式会社
Priority date: 2021-01-20
Filing date: 2022-01-19
Publication date: 2022-07-28
Also published as: JPWO2022158498A1

Abstract

[Problem] To provide: a fine cellulose fiber–containing solvent that makes it possible to suitably exploit the effects of a functional composition, such as an agrochemical, that is included in a spray; a practical liquid that includes the fine cellulose fiber–containing solvent; and a preparation method for the practical liquid. [Solution] This fine cellulose fiber–containing solvent is for improving the wetting properties and suppressing drippage of a liquid that contains a functional composition. The fine cellulose fiber–containing solvent contains anionic fine cellulose fibers that have had some of the hydroxyl groups thereof replaced with an anionic functional group and have an average fiber width of 1–1000 nm. When the anionic fine cellulose fibers have been dispersed in pure water such that the solid concentration is 0.2–1.0 mass%, the type-B viscosity as measured using a type-B viscometer is 1000–50000 mPa·s. The fine cellulose fiber–containing solvent makes it possible for a practical liquid to exhibit excellent wetting properties and drippage suppression and can thereby improve the functionality of the practical liquid.

Description

Solvent containing fine cellulose fibers, application liquid and method for preparing application liquid

The present invention relates to a fine cellulose fiber-containing solvent, application liquid, and application liquid preparation method. More specifically, it relates to a fine cellulose fiber-containing solvent containing fine cellulose fibers having an anionic functional group, an application liquid containing this fine cellulose fiber-containing solvent, and a method for preparing an application liquid for preparing this application liquid.

In general, spraying pesticides is essential to protect crops from pests and the like. As a method of spraying agricultural chemicals on crops, a method of spraying a spray liquid obtained by diluting a stock solution of the agricultural chemical with water using a sprayer or the like is generally adopted. Here, a wax layer that easily repels water is formed on the surface of the leaves of crops. For this reason, most of the spray liquid that has been sprayed runs off, and the effect of the agricultural chemical cannot be sufficiently exhibited. Therefore, a spreading agent is usually added to the spray solution. This spreading agent is a solvent containing a surfactant as a main component, and improves the wettability of the spray liquid adhering to the crops. On the other hand, a phenomenon occurs in which the spray liquid adhering to the crops easily flows down (easily drips).
Therefore, conventionally, a spreader containing a thickener has been proposed in order to suppress dripping of the spray liquid adhering to the crops (eg, Patent Documents 1 to 3).
Patent Document 1 discloses a water-soluble carboxymethyl cellulose (CMC) and a granular wettable powder using its sodium salt as a spreading agent. Further, Patent Document 2 discloses, as a spreading agent, a spreader composition for agricultural chemicals containing a polysaccharide such as starch. Patent Document 3 discloses an agricultural spreading agent containing a cellulose derivative of water-soluble hydroxypropylcellulose (HPC) or hydroxypropylmethylcellulose (HPMC) as a spreading agent.

JP-A-2005-132741 JP 2012-72116 A JP 2011-207828 A

However, although the spreading agents of Patent Documents 1 to 3 have a certain degree of viscosity, they are used after being diluted several hundred to 1,000 times before use. not be suppressed to
Therefore, in the conventional technology, even if a spray liquid containing a functional composition such as an agricultural chemical or a fertilizer is sprayed on agricultural crops, most of it runs off and the effect of the functional composition contained in the spray liquid is not sufficiently obtained. The reality is that it has not been able to demonstrate.

In view of the above circumstances, the present invention provides a fine cellulose fiber-containing solvent capable of appropriately exhibiting the effects of a functional composition such as an agricultural chemical contained in a spray liquid, an application liquid containing the fine cellulose fiber-containing solvent, and such an application liquid. The object is to provide a method for preparing an application liquid, which is the preparation method of

As a result of extensive studies aimed at solving the above problems, the present inventors found that the inclusion of fine cellulose fibers exhibited wettability and viscosity with respect to liquids, and completed the present invention.

The fine cellulose fiber-containing solvent of the present invention is a solvent used for improving the wettability of the liquid contained in the functional composition and suppressing dripping, and part of the hydroxyl groups are substituted with anionic functional groups. , contains anionic fine cellulose fibers having an average fiber width of 1 nm to 1000 nm, and the anionic fine cellulose fibers are added to pure water so that the solid content concentration is 0.3% to 1.0% by mass. It is characterized by having a B-type viscosity of 1000 mPa·s or more and 50000 mPa·s or less in a dispersed state measured using a B-type viscometer (20° C., rotation speed 6 rpm, 3 minutes).
The application liquid of the present invention is a liquid containing water, a functional composition, and the fine cellulose fiber-containing solvent of the present invention used for improving wettability and suppressing dripping.
The application liquid preparation method of the present invention is a method of preparing a liquid containing water, a functional composition, and the fine cellulose fiber-containing solvent of the present invention used for improving wettability and suppressing dripping. , the solvent contains anionic fine cellulose fibers having an average fiber width of 1 nm to 1000 nm in which some of the hydroxyl groups are substituted with an anionic functional group, and the solid content concentration of the anionic fine cellulose fibers is , 0.3% by mass to 1.0% by mass.

According to the present invention, it is possible to provide a fine cellulose fiber-containing solvent capable of exhibiting excellent wettability and suppression of liquid dripping. When the application liquid containing the fine cellulose fiber-containing solvent of the present invention is used, the application liquid can adhere appropriately to the object and efficiently exhibit the functions of the application liquid, and the application liquid can be obtained. A method of preparation can be provided.

FIG. 10 is a diagram showing experimental results of Experiment 1; 1 is a diagram showing an example of a conductivity titration curve of Experiment 1. FIG. 1 is a diagram showing an example of a conductivity titration curve of Experiment 1. FIG. 1 is a diagram showing an example of a conductivity titration curve of Experiment 1. FIG. FIG. 10 is a schematic explanatory diagram of a method for evaluating liquid dripping in Experiment 2; FIG. 10 is a schematic illustration of a wettability evaluation method in Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2; FIG. 10 is a diagram showing experimental results of Experiment 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described based on the drawings.
Since the fine cellulose fiber-containing solvent of the present embodiment contains the anionic fine cellulose fibers, the liquid using the fine cellulose fiber-containing solvent can be appropriately adhered to the surface of the object. It is characterized by being able to efficiently exhibit the function based on the functional composition possessed by.
Specifically, the fine cellulose fiber-containing solvent of the present embodiment can exhibit excellent wettability and excellent suppression of dripping with respect to the liquid containing the fine cellulose fiber-containing solvent. By applying this liquid to an object, the liquid can be appropriately adhered to the object. Therefore, it is possible to efficiently exhibit the function of the liquid based on the functional composition on the object.

The application liquid of this embodiment is a liquid containing water, the functional composition, and the fine cellulose fiber-containing solvent of this embodiment. That is, the application liquid of the present embodiment corresponds to the liquid containing the fine cellulose fiber-containing solvent of the present embodiment in the description of the fine cellulose fiber-containing solvent of the present embodiment described above.

The object to which the application liquid of the present embodiment is applied (object to be applied) can be appropriately selected according to the function of the contained functional composition. Examples of functional compositions include agricultural chemicals, fertilizers, fungicides, disinfectants, soil conditioners, and plant growth promoters. Details of the functional composition will be described later.
For example, when the functional composition is an agricultural chemical or a plant growth promoter, agricultural crops (including trees and agricultural and forestry products) are targets. Also, when the functional composition is a fertilizer, crops are also subject. That is, when the functional composition is an agricultural composition such as an agricultural chemical or a fertilizer, the target object can be mainly agricultural products. When the functional composition is a bactericide or a disinfectant, river water, agricultural water, etc. are the subject matter. In addition, when the functional composition is a disinfectant, if diluted, it can be used for domestic animals, pets, and the like. Furthermore, when the functional composition is a soil improver or a plant growth promoter, soil is the subject.

Note that the water used for the application liquid in this embodiment is not particularly limited. For example, general tap water, pure water such as ion-exchanged water or distilled water, ultrapure water, river water, agricultural water, or other water that does not affect the object may be used.

(Fine cellulose fiber-containing solvent of the present embodiment)
The fine cellulose fiber-containing solvent of the present embodiment (hereinafter simply referred to as fine cellulose fiber-containing solvent) is a solvent containing fine cellulose fibers having an anionic functional group.
This fine cellulose fiber-containing solvent contains the fine cellulose fibers so that the solid content concentration is, for example, 0.1% by mass to 2.0% by mass. In this specification, unless otherwise specified, "~" includes values before and after. For example, a solid content concentration of 0.1 mass % to 2.0 mass % indicates a range including solid content concentrations of 0.1 mass % and 2.0 mass %.
The content of the fine cellulose fibers is preferably 0.2% by mass or more and 2.0% by mass or less in terms of solid concentration. It is more preferably 0.3% by mass or more and 1.0% by mass or less, and still more preferably 0.5% by mass or more and 1.0% by mass or less.

On the other hand, if the content of the fine cellulose fibers is less than 0.1% by mass, the thickening action is not sufficient and the liquid dripping suppression effect is not exhibited. Also, if the content of the fine cellulose fibers is more than 2.0% by mass, the cellulose fibers gel when mixed with a desired liquid, which may result in poor handleability.

(Average fiber width of anionic fine cellulose fibers)
The above fine cellulose fibers are anionic fine cellulose fibers having an average fiber width of 1 nm to 1000 nm, in which a portion of the hydroxyl groups of cellulose are substituted with an anionic functional group. Hereinafter, these fine cellulose fibers are simply referred to as anionic fine cellulose fibers (unless otherwise specified, chemically modified fine cellulose fibers refer to these anionic fine cellulose fibers).
The average fiber width of the anionic fine cellulose fibers is, for example, 1 nm or more and 500 nm or less. It is preferably 1 nm or more and 100 nm or less, more preferably 3 nm or more and 30 nm or less.

On the other hand, if the average fiber width of the anionic fine cellulose fibers is smaller than 1 nm, the cellulose molecules will dissolve in water, making it difficult for the fine cellulose fibers to exhibit high viscosity. On the other hand, if the average fiber width of the anionic fine cellulose fibers is larger than 1000 nm, it cannot be said that they are fine cellulose fibers, but are merely fibers contained in ordinary pulp, so that it is difficult to develop high viscosity as fine cellulose fibers. Also, clogging occurs in devices having narrow flow paths, resulting in poor handling.

(Viscosity of anionic fine cellulose fibers)
Anionic fine cellulose fibers are fine fibers that exhibit a predetermined viscosity when dispersed in pure water. Specifically, the viscosity of the anionic fine cellulose fibers is measured by using a B-type viscometer to determine the viscosity of the dispersion in pure water so that the solid content concentration is 0.3% by mass to 1.0% by mass. measured using
For example, the B-type viscosity of the anionic fine cellulose fibers (20° C., rotation speed 6 rpm, 3 minutes) is preferably 1000 mPa·s or more and 50000 mPa·s or less. It is more preferably 1000 mPa·s to 25000 mPa·s, still more preferably 9000 mPa·s to 25000 mPa·s, still more preferably 9000 mPa·s to 20000 mPa·s.

On the other hand, when the B-type viscosity of the anionic fine cellulose fibers is lower than 1000 mPa·s, the fluidity is high, so it is difficult to contribute to the suppression of liquid dripping when used in the liquid containing the functional composition. In addition, when the B-type viscosity of the anionic fine cellulose fibers is higher than 50000 mPa·s, it becomes difficult to mix when used in the liquid containing the functional composition, resulting in poor handleability.

Here, the present inventors have found for the first time that droplets containing anionic fine cellulose fibers exhibit wettability. That is, the present inventors found that when a liquid containing anionic fine cellulose fibers is applied to an object, the liquid adhering to the surface of the object is not repelled on the object surface. It was found for the first time that it can be attached so as to spread over the surface.
In addition, the evaluation method of wettability is evaluated by the method described in Examples described later.

Since the fine cellulose fiber-containing solvent contains the above-mentioned anionic fine cellulose fibers, when added to a desired liquid, it can exhibit wettability to this liquid. Further, since the anionic fine cellulose fibers exhibit the above-mentioned viscosity when dispersed in water, the viscosity can be imparted to the liquid to which the fine cellulose fiber-containing solvent is added.
Therefore, when the liquid to which the fine cellulose fiber-containing solvent is added is applied to the object, the liquid adheres to the surface of the object so as to spread and dripping of the adhered liquid can be suppressed. That is, dripping of the liquid after application can be suppressed. In addition, the evaluation of this liquid sagging can be performed by the method described in Examples described later.

As described above, by adding a fine cellulose fiber-containing solvent to a desired liquid and applying this liquid to a subject, the liquid can be appropriately adhered to the surface of the subject. Specifically, when the liquid containing the fine cellulose fiber-containing solvent is applied to the object, the applied liquid spreads along the surface of the object without being repelled on the surface of the object. can be attached to Moreover, since the liquid adhering to the surface of the object can be prevented from dripping down, it is possible to maintain the state of spreading and adhering along the surface of the object. In other words, by including the fine cellulose fiber-containing solvent in the desired liquid, the surface of the object after application can be covered with the applied liquid. Moreover, the state can be maintained for a long period of time. Therefore, if the liquid contains a functional composition such as an agricultural chemical, the effect of the functional composition can be exhibited continuously and appropriately.
The amount of the fine cellulose fiber-containing solvent to be added may be adjusted so that the solid content concentration (% by mass) of the anionic fine cellulose fibers in the liquid is within a predetermined range.

(Anionic fine cellulose fiber)
The anionic fine cellulose fibers are obtained by substituting some of the hydroxyl groups of the cellulose fibers represented by the general formula (1) (hereinafter simply referred to as cellulose) with anionic functional groups.

(general formula (1))

Examples of the anionic functional group include, for example, a sulfo group represented by general formula (2), a phosphoric acid group represented by general formula (3), a phosphorous acid group represented by general formula (4), and a general formula (5). A carboxy group represented by the formula (6) and a carboxymethyl group represented by the general formula (6) can be mentioned.
The anionic fine cellulose fibers may be substituted with one or a mixture of two or more of the above functional groups. A known method can be employed for substituting the hydroxyl groups of the anionic fine cellulose fibers with various functional groups. Each production method has advantages and disadvantages, but among these, the method of substituting the sulfo group has the advantage of being easier to carry out than the other production methods.

The term “substitution” as used herein refers to the replacement of hydroxyl groups of cellulose with anionic functional groups. It means a state in which a functional group is bonded.
Specifically, in the present specification, the hydroxyl groups of cellulose are substituted with anionic functional groups, meaning that at least part of the hydroxyl groups (—OH groups) of cellulose are substituted with anionic functional groups. A part of the hydroxyl group means to include not only "H" (hydrogen atom) of "--OH group" but also "OH". That is, in the structure in which a part of the hydroxyl groups of cellulose is substituted with an anionic functional group, an anionic functional group (for example, general formula (2) ~General formula (6)) is bonded to the carbon of cellulose and the oxygen atom (O) of the hydroxyl group and an anionic functional group (a so-called ester bond, for example, in the case of general formula (2), general In addition to general formula (8) for general formula (7) and general formula (3), general formula (13) for general formula (4), and general formula (9) for general formula (5), A structure in which an anionic functional group is directly bonded to the carbon to which the hydroxyl group of cellulose is bonded by bonding an anionic functional group instead of the "OH" of the hydroxyl group (for example, in the case of general formula (2), the general formula (10), general formula (11) for general formula (3), general formula (14) for general formula (4), general formula (12) for general formula (5), general formula (6) ), general formula (15)) is also included.

When the anionic functional group is a sulfo group or a phosphate group, some of the hydroxyl groups of cellulose are replaced (that is, substituted) by a sulfo group or a phosphate group through a substitution reaction. When the functional group of is a carboxy group, it is a structure in which a part of the hydroxyl group is replaced (that is, substituted) with the carboxy group by an oxidation reaction.

(general formula (2))

(In the formula, Z represents a hydrogen ion, metal ion, onium ion or cationic organic compound.)

(general formula (3))

(general formula (4))

(general formula (5))

(general formula (6))

(general formula (7))

(In the formula, R represents a structure obtained by removing some hydroxyl groups from cellulose (general formula (1)).Z represents a hydrogen ion, a metal ion, an onium ion, or a cationic organic compound.)

A maximum of three sulfo groups can be bonded to D-glucose of cellulose.
Therefore, the sulfo group in general formula (7) can be represented by (--SO ₃ ⁻ ) _r ·Z ^r+ . Then, Z is at least selected from the group consisting of hydrogen ions, alkali metal cations, monovalent transition metal ions, onium ions (ammonium ions, aliphatic ammonium ions, aromatic ammonium ions, etc.), and cationic polymers. It is one type. In some cases, Z is at least one selected from the group consisting of compounds containing two or more cationic functional groups in the molecule, such as alkaline earth metal cations, polyvalent metal cations, and diamines. .

(general formula (8))

A maximum of three phosphate groups can be bound to D-glucose of cellulose.
Therefore, the phosphate group in general formula (8) can be represented by (-PO ₃ ^2- ) _r ·Z ^r+ . Then, Z is at least selected from the group consisting of hydrogen ions, alkali metal cations, monovalent transition metal ions, onium ions (ammonium ions, aliphatic ammonium ions, aromatic ammonium ions, etc.), and cationic polymers. It is one type. In some cases, Z is at least one selected from the group consisting of compounds containing two or more cationic functional groups in the molecule, such as alkaline earth metal cations, polyvalent metal cations, and diamines. .

(general formula (9))

A maximum of three carboxy groups can be bound to D-glucose of cellulose. Therefore, the carboxy group in general formula (9) can be represented by ( _-CO2- ⁾ _rZr ⁺ . Then, Z is at least selected from the group consisting of hydrogen ions, alkali metal cations, monovalent transition metal ions, onium ions (ammonium ions, aliphatic ammonium ions, aromatic ammonium ions, etc.), and cationic polymers. It is one type. In some cases, Z is at least one selected from the group consisting of compounds containing two or more cationic functional groups in the molecule, such as alkaline earth metal cations, polyvalent metal cations, and diamines. .

(general formula (10))

The sulfo group in general formula (10) can also be represented in the same manner as in general formula (7), and Z can also include similar compounds.

(general formula (11))

The phosphate group in general formula (11) can also be represented in the same manner as in general formula (8), and Z can also include similar compounds.

(general formula (12))

The carboxy group in general formula (12) can also be represented in the same manner as in general formula (9), and Z can also include similar compounds.

In addition, in the case of a phosphite group and a carboxymethyl group, it can be shown as follows.

(general formula (13))

Incidentally, like the phosphate group, up to three phosphite groups can be bound to D-glucose of cellulose.
Therefore, the phosphite group in general formula (13) can be represented by (-HPO ₂ ⁻ ) _r ·Z ^r+ . Then, Z is at least selected from the group consisting of hydrogen ions, alkali metal cations, monovalent transition metal ions, onium ions (ammonium ions, aliphatic ammonium ions, aromatic ammonium ions, etc.), and cationic polymers. It is one type. In some cases, Z is at least one selected from the group consisting of compounds containing two or more cationic functional groups in the molecule, such as alkaline earth metal cations, polyvalent metal cations, and diamines. .

(general formula (14))

In addition, phosphorous acid in general formula (14) can also be represented in the same manner as in general formula (13), and Z can also include similar compounds.

(general formula (15))

Incidentally, like the carboxy group, a maximum of three carboxymethyl groups can be bound to D-glucose of cellulose.
Therefore, the carboxymethyl group in general formula (15) can be represented by (--CH ₂ CO ₂ ⁻ ) _r ·Z ^r+ . Then, Z is at least selected from the group consisting of hydrogen ions, alkali metal cations, monovalent transition metal ions, onium ions (ammonium ions, aliphatic ammonium ions, aromatic ammonium ions, etc.), and cationic polymers. It is one type. In some cases, Z is at least one selected from the group consisting of compounds containing two or more cationic functional groups in the molecule, such as alkaline earth metal cations, polyvalent metal cations, and diamines. .

(sulfonated fine cellulose fiber)

In the following, an anionic fine cellulose fiber in which a part of hydroxyl groups of cellulose is substituted with a sulfo group will be described as a representative.
The anionic fine cellulose fibers substituted with sulfo groups are referred to as sulfonated fine cellulose fibers.

The sulfonated fine cellulose fibers contain a plurality of finer cellulose fibers (hereinafter referred to as unit fibers). Specifically, the sulfonated fine cellulose fibers are fibers formed by connecting a plurality of unit fibers. In this unit fiber, at least part of the hydroxyl groups (--OH groups) of the cellulose (a chain polymer in which D-glucose is β(1→4) glycoside-bonded) constituting the fiber is a sulfo group as described above. is replaced by
In the sulfonated fine cellulose fibers, functional groups other than sulfo groups may be bonded to some of the hydroxyl groups of the fine cellulose fibers as described above.
In the following description, the case where only sulfo groups are introduced into the hydroxyl groups of the cellulose fibers constituting the sulfonated fine cellulose fibers will be described as a representative.

The amount of sulfo groups introduced into the sulfonated fine cellulose fibers is not particularly limited.
For example, the amount of sulfo groups introduced per 1 g (mass) of sulfonated fine cellulose fibers is 0.1 mmol/g to 3.0 mmol/g. It is more preferably 0.1 mmol/g or more and 2.0 mmol/g or less, and still more preferably 0.1 mmol/g or more and 1.5 mmol/g or less.
Moreover, the lower limit is preferably 0.5 mmol/g or more. More preferably, it is 1.0 mmol/g or more.

When the amount of sulfo groups introduced per 1 g (mass) of sulfonated fine cellulose fibers is less than 0.1 mmol/g, the hydrogen bonding between fibers is strong, and dispersibility tends to decrease. Conversely, when the amount of the sulfo group introduced is 0.1 mmol/g or more, the dispersibility can be easily improved, and when it is 0.4 mmol/g or more, the electronic repulsion can be strengthened. It becomes easier to stably maintain the dispersed state. On the other hand, if the amount of sulfo groups exceeds 3.0 mmol/g, there is a concern that the crystallinity will be lowered or the polymer will be dissolved, making it difficult to achieve the desired viscosity, and the cost of introducing the sulfo groups tends to increase.

The amount of sulfo groups introduced into the sulfonated fine cellulose fibers can be evaluated by directly measuring the sulfo groups, and can also be evaluated by the amount of sulfur introduced due to the sulfo groups.

In the former measurement method, for example, after treating sulfonated fine cellulose fibers with an ion-exchange resin, the conductivity can be calculated based on the value obtained by measuring the electrical conductivity while dropping an aqueous sodium hydroxide solution.
The latter measurement method is, for example, burning a predetermined amount of sulfonated fine cellulose fibers, measuring the sulfur content in the burned material using a combustion ion chromatograph by a method conforming to IEC 62321, and obtaining the value. calculated based on

Since the number of sulfur atoms in the sulfo group is 1, the amount of sulfur introduced: the amount of sulfo groups introduced is 1:1. For example, when the amount of sulfur introduced per 1 g (mass) of sulfonated fine cellulose fibers is 0.1 mmol/g, the amount of sulfo groups introduced is naturally 0.1 mmol/g.

To explain the former measurement method more specifically, first, a 1/10 volume ratio of a strongly acidic ion exchange resin (Amberjet 1024, manufactured by Organo Co., Ltd.; conditioned ) is added and shaken for 1 hour or longer (treatment with ion exchange resin). Then, it is poured onto a mesh with an opening of about 90 μm to 200 μm to separate the resin from the slurry. In the subsequent titration with alkali, the change in electrical conductivity value is measured while adding 0.5N aqueous sodium hydroxide solution to the slurry containing sulfonated fine cellulose fibers after treatment with the ion exchange resin. Plotting the obtained measurement data with the electrical conductivity on the vertical axis and the titration amount of sodium hydroxide on the horizontal axis yields a curve, and an inflection point can be confirmed. The titration amount of sodium hydroxide at this point of inflection corresponds to the amount of sulfo groups, and the amount of sodium hydroxide at this point of inflection is divided by the solid content of the sulfonated fine cellulose fibers used for measurement, thereby introducing sulfo groups. You can ask for the quantity.

As will be described later, when chemically treated sulfonated pulp is pulverized to prepare sulfonated fine cellulose fibers, it may be determined from the amount of sulfur introduced into the sulfonated pulp before pulverization.

The sulfonated fine cellulose fibers are, as described above, fine cellulose fibers obtained by refining cellulose fibers, and the fibers are very fine fibers.
The average fiber width of the sulfonated fine cellulose fibers can be measured using known techniques. For example, sulfonated fine cellulose fibers are dispersed in a solvent such as pure water to prepare a mixed solution having a predetermined mass %. Then, this mixed solution is spin-coated on a silica substrate coated with PEI (polyethyleneimine), and sulfonated fine cellulose fibers on this silica substrate are observed.

As an observation method, for example, a scanning probe microscope (eg, SPM-9700 manufactured by Shimadzu Corporation) can be used. By randomly selecting 20 sulfonated fine cellulose fibers in the observed image and measuring and averaging the width of each fiber, the average fiber width of the sulfonated fine cellulose fibers can be obtained.

(Method for producing sulfonated fine cellulose fibers)
Next, a method for producing sulfonated fine cellulose fibers will be described.
In addition, in the following manufacturing method, the sulfonated pulp manufactured by the sulfonated pulp manufacturing method can be manufactured by subjecting the sulfonated pulp to a micronization treatment, but the manufacturing method is not limited thereto.

The outline of this sulfonated pulp manufacturing method is to manufacture sulfonated pulp (hereinafter simply referred to as sulfonated pulp) as a raw material by subjecting a fiber raw material containing cellulose (for example, wood pulp) to a chemical treatment process.

This chemical treatment process is a method in which the supplied fiber raw material is brought into contact with a reaction liquid (contact process), and then subjected to a heating reaction (reaction process) to sulfonate the hydroxyl groups of cellulose.

In this specification, the fiber material refers to fibrous pulp containing cellulose molecules. Pulp is a fibrous member in which multiple celluloses are aggregated. This cellulose is an aggregate of a plurality of fine fibers (for example, microfibrils, etc.). These fine fibers are aggregates of a plurality of cellulose molecules (hereinafter sometimes simply referred to as cellulose), which are chain polymers in which D-glucose is β(1→4) glycoside-bonded.

It should be noted that it is preferable to wash the fiber raw material to be used in advance. For example, filtration and dehydration using water on a 200-mesh or 235-mesh sieve is desirable because fine fibers and dust can be sieved out, and handleability during production is improved. In other words, pulp is an aggregated fiber of cellulose having a size of 200-mesh or 235-mesh residue. Details of the fiber raw material will be described later.

As described above, the chemical treatment step includes a contacting step of contacting cellulose, which is a fiber raw material containing cellulose such as pulp, with sulfamic acid, which is a sulfonating agent having a sulfo group, and urea, and adding and a reaction step of substituting and introducing a sulfo group into at least part of the hydroxyl groups of the cellulose obtained. Each step will be described in order below.

(Contact process)
The contacting step is a step of bringing sulfamic acid and urea into contact with a fibrous raw material containing cellulose. This contacting step is not particularly limited as long as it is a method capable of causing the above contact.
For example, the fibrous raw material (for example, wood pulp) may be immersed in a reaction liquid obtained by dissolving sulfamic acid and urea in a solvent to impregnate the fibrous raw material with the reaction liquid. Alternatively, sulfamic acid and urea may be separately applied, impregnated, or sprayed onto the fiber raw material. For example, if a method of impregnating the fiber raw material with the reaction liquid by immersing the fiber raw material in the reaction liquid is adopted, it is possible to obtain the advantage that the sulfamic acid and the urea are easily brought into contact with the fiber raw material uniformly.

The solvent for dissolving sulfamic acid and urea is not particularly limited.
For example, in addition to water alone (including pure water such as ion-exchanged water and distilled water, as well as tap water, etc.), ethanol, methanol, acetic acid, formic acid, 2-propanol, nitromethane, and protons such as ammonia water polar solvents, acetone, ethyl acetate, tetrahydrofuran (THF), dimethylformamide (DMF), acetonitrile, dimethylsulfoxide (DMSO), dimethylsulfide (DMS), aprotic polar solvents such as dimethylacetamide (DMA), Non-polar solvents such as diethyl ether, benzene, toluene, hexane, chloroform, and 1,4-dioxane can be mentioned, and these may be used alone or in combination of two or more. may In particular, water is preferable from the viewpoint of easily dissolving sulfamic acid and urea.

(Mixing ratio of reaction solution)
When adopting the method of impregnating the fiber raw material with the reaction liquid by immersing the fiber raw material in the reaction liquid, the mixing ratio of sulfamic acid and urea contained in the reaction liquid is not particularly limited. The mixing ratio is adjusted to that described in Examples described later.
For example, the concentration ratio (g/L) of the sulfonating agent and urea or/and its derivative is 4:1 (1:0.25), 2:1 (1:0.5), 1:1, 2 : 3 (1:1.5) and 1:2.5.

(Contact amount of reaction liquid)
The amount of the reaction liquid brought into contact with the fiber raw material is such that the sulfamic acid and urea in the reaction liquid are brought into contact with the fiber raw material at a predetermined ratio.
For example, in a state in which the reaction liquid and the fiber raw material are brought into contact, the sulfonating agent contained in the reaction liquid is 1 part by mass to 20,000 parts by mass with respect to 100 parts by mass of the dry mass of the fiber raw material. The amount of urea and/or its derivative contained in is 1 part by mass to 100,000 parts by mass with respect to 100 parts by mass of the dry mass of the fiber raw material.

The fiber material impregnated with the reaction liquid when subjected to the reaction process of the next step, for example, is in the state of being impregnated with the reaction liquid, that is, the state of contact between the fiber material and the reaction liquid. Examples include a state in which no reaction is performed, and a state in which water is actively removed from a state in which the fiber raw material and the reaction liquid are brought into contact with each other.

As the latter method, for example, the fiber raw material is taken out from the state in which the reaction liquid and the fiber raw material are brought into contact with each other, and the fiber raw material is dried naturally by air drying or the like. prepared by further air-drying the dehydrated and filtered material, further drying the dehydrated and filtered material using a circulating air dryer, and further heating the dehydrated and filtered material. Those prepared by drying using a type dryer, those prepared by drying the reaction liquid and the fiber raw material in contact with each other using a circulating air dryer or a heating dryer, etc. is meant to contain

The fiber raw material impregnated with the reaction liquid when subjected to the next reaction step is in a state where the above-mentioned active water removal is not performed, or in a state where a certain amount of water is removed after active water removal. may be of Further, when the moisture is removed by drying, there is no particular problem even if the moisture content after drying is about 1%.

(Reaction step)
The fiber raw material impregnated with the reaction solution prepared in the contacting step as described above is supplied to the reaction step in the next step.
In this reaction step, the cellulose, sulfamic acid, and urea contained in the fiber raw material supplied from the contacting step are reacted to substitute the sulfo groups of sulfamic acid for the cellulose hydroxyl groups in the cellulose, thereby producing the fiber raw material. It is a step of introducing a sulfo group into the cellulose contained in. That is, this reaction step is a step of carrying out a sulfonation reaction in which sulfo groups are substituted for the cellulose hydroxyl groups in the cellulose contained in the fiber raw material impregnated with the reaction solution.

This reaction step is not particularly limited as long as it is a method capable of performing a sulfonation reaction in which hydroxyl groups of cellulose in the fiber raw material are substituted with sulfo groups.
For example, a method can be employed in which the sulfonation reaction is accelerated by heating the fiber raw material. Hereinafter, the case where the sulfonation reaction is performed by this heating method will be described as a representative.

(Reaction temperature in reaction step)
The reaction temperature in the reaction step is not particularly limited as long as it is a temperature at which a sulfo group can be introduced into the cellulose constituting the fiber raw material while suppressing thermal decomposition and hydrolysis reaction of the fiber.
For example, the ambient temperature of the fiber raw material supplied to the reaction step is adjusted to 100° C. or higher and 200° C. or lower. The ambient temperature is preferably 120° C. or higher and 200° C. or lower.
On the other hand, if the ambient temperature during heating is higher than 200° C., thermal decomposition of the fibers may occur, or discoloration of the fibers may proceed more rapidly. Further, when the reaction temperature is lower than 100°C, the resulting sulfonated pulp tends to be less transparent.
Therefore, from the viewpoint of the transparency of the obtained sulfonated pulp, the reaction temperature (specifically, the ambient temperature) in the reaction step is 100° C. or higher and 200° C. or lower, preferably 120° C. or higher and 180° C. or lower. The temperature is preferably 120°C or higher and 160°C or lower.

The heater or the like used in the reaction step is not particularly limited as long as it can directly or indirectly heat the fiber raw material after the contact step while satisfying the above requirements.
For example, a hot press method using a known dryer, vacuum dryer, microwave heating device, autoclave, infrared heating device, or heat press (for example, AH-2003C manufactured by AS ONE Co., Ltd.) can be employed. In particular, from the viewpoint of operability, it is preferable to use a circulating air dryer because gas may be generated in the reaction process.

(Reaction time in reaction step)
The heating time (that is, the reaction time) when the above heating method is employed as the reaction step is not particularly limited as long as the sulfo group can be appropriately introduced into the cellulose as described above.
For example, the reaction time in the reaction step is adjusted to be 1 minute or more in the above range. The time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and still more preferably 15 minutes or longer.
On the other hand, when the reaction time is shorter than 1 minute, it is presumed that the substitution reaction of the sulfo group with respect to the hydroxyl group of cellulose hardly proceeds. Also, even if the heating time is too long, there is a tendency that an increase in the amount of sulfo groups introduced cannot be expected.
Therefore, the reaction time when the above heating method is employed as the reaction step is not particularly limited, but from the viewpoint of the reaction time and operability, it is preferably 5 minutes or more and 300 minutes or less, more preferably 5 minutes or more and 120 minutes or less. Better to

(fiber raw material)
The fiber raw material used in the sulfonated pulp manufacturing method is not particularly limited as long as it contains cellulose as described above.
For example, what is generally called pulp may be used, and what contains cellulose isolated from sea squirts, seaweed, etc. can be used as the fiber raw material, but as long as it is composed of cellulose molecules, , can be anything.
Examples of the pulp include wood pulp (hereinafter simply referred to as wood pulp), dissolving pulp, cotton pulp such as cotton linter, straw, bagasse, kozo, mitsumata, hemp, kenaf, fruits, and the like. Non-wood pulp, waste paper pulp produced from waste newspaper, waste magazine paper, waste cardboard, etc., but not limited to these. From the standpoint of availability, wood pulp is easy to employ as a fiber raw material.

There are various types of this wood pulp, but there is no particular limitation in use.
Examples thereof include softwood kraft pulp (NBKP), hardwood kraft pulp (LBKP), thermomechanical pulp (TMP) and other papermaking pulps. When the above pulp is used as the fiber raw material, one type of the pulp described above may be used alone, or two or more types may be mixed and used.

(Washing process after reaction process)
After the reaction step in the chemical treatment step, a washing step of washing the sulfonated pulp after introduction of the sulfo group may be included.
The surface of the sulfonated pulp after introduction of the sulfo group is acidified due to the influence of the sulfonating agent. In addition, unreacted reaction liquid also exists. For this reason, if a washing step is provided to ensure that the reaction is completed and to neutralize the excess reaction solution by removing the excess reaction solution, the handleability can be improved.

This washing step is not particularly limited as long as the sulfonated pulp after introduction of the sulfo group can be made substantially neutral.
For example, a method of washing with pure water or the like until the sulfonated pulp after introduction of the sulfo group becomes neutral can be adopted. Further, neutralization cleaning using an alkali or the like may be performed. When performing neutralization washing, an inorganic alkali compound, an organic alkali compound, etc. are mentioned as an alkali compound contained in an alkali solution. Examples of inorganic alkali compounds include hydroxides, carbonates, and phosphates of alkali metals. Examples of organic alkali compounds include ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds, and hydroxides of heterocyclic compounds.

Next, the sulfonated pulp prepared using the sulfonated pulp manufacturing method as described above is supplied to the micronization process. The sulfonated pulp supplied to the refining treatment step is refined to become sulfonated fine cellulose fibers.
In addition, the sulfonated pulp is dried until its moisture content (%) reaches an equilibrium state before being supplied to the pulverization treatment step.

(Miniaturization process)
The refining step is a step of refining the sulfonated pulp into fine fibers of a predetermined size (for example, nano-level).
A processing apparatus used in this miniaturization process is not particularly limited as long as it has the above functions.
For example, low-pressure homogenizers, high-pressure homogenizers, grinders (stone mill type pulverizers), ball mills, cutter mills, jet mills, short-screw extruders, twin-screw extruders, ultrasonic stirrers, household mixers and the like can be used. The processing device is not limited to these devices. Among the processing devices, a high pressure homogenizer is preferred because it can uniformly apply force to the material and is excellent in homogenization.

When using a high-pressure homogenizer in the micronization process, the sulfonated pulp described above is supplied in a state of being dispersed in a mixed solution of water and a water-soluble solvent. A state in which the sulfonated pulp is dispersed in this mixed solution is called a slurry.

The solid content concentration (% by mass) of the sulfonated pulp in this slurry is not particularly limited.
For example, a solution adjusted so that the solid content concentration of the sulfonated pulp in the slurry is 0.1% by mass to 20% by mass is supplied to a processing apparatus such as a high-pressure homogenizer.
When the slurry adjusted so that the solid content concentration of the sulfonated pulp is 0.5% by mass is supplied to a processing device such as a high-pressure homogenizer, sulfonated fine cellulose fibers having the same solid content concentration are dispersed in the mixed solution. A dispersion is obtained.

In the above example, the case where the slurry obtained by dispersing the sulfonated pulp in water is subjected to the micronization treatment is explained, but other solvent or the like may be mixed in addition to water.
For example, in the refining treatment step, a mixture of the sulfonated pulp slurry and a water-soluble solvent may be subjected to refining treatment. Specifically, a slurry in which a water-soluble solvent, a sulfonated pulp and water are mixed at a predetermined ratio may be supplied to a processing apparatus for micronization. In this case, the blending ratio of water, water-soluble solvent, and sulfonated fine cellulose fibers in the dispersion obtained after the pulverization treatment is the same as the blending ratio of water, water-soluble solvent, and sulfonated pulp supplied to the processor. . That is, a dispersion is obtained in which water, a water-soluble solvent, and sulfonated fine cellulose fibers are mixed in a predetermined ratio at the same time as the micronization treatment.
In addition to the water-soluble solvent, a thickening agent, an ultraviolet absorber, an ultraviolet dispersant, a moisturizing agent, and the like may be mixed in the sulfonated pulp slurry to be supplied to the pulverization treatment.

(Phosphorylated fine cellulose fiber)
In the following, an anionic fine cellulose fiber in which some of the hydroxyl groups of cellulose are substituted with phosphoric acid groups will be described as a representative.
The anionic fine cellulose fibers substituted with phosphate groups are referred to as phosphorylated fine cellulose fibers.

The amount of phosphate groups introduced into the phosphorylated fine cellulose fibers is not particularly limited.
For example, the amount of phosphoric acid groups introduced per 1 g (mass) of phosphorylated fine cellulose fibers is 0.1 mmol/g to 3.0 mmol/g. It is more preferably 0.1 mmol/g or more and 2.5 mmol/g or less, and still more preferably 0.1 mmol/g or more and 2.0 mmol/g or less.
Moreover, the lower limit is preferably 0.3 mmol/g or more. It is more preferably 0.4 mmol/g or more, still more preferably 1.0 mmol/g or more.

When the amount of phosphoric acid groups introduced per 1 g (mass) of phosphorylated fine cellulose fibers is less than 0.1 mmol/g, the hydrogen bonding between fibers is strong, so dispersibility tends to decrease. Conversely, when the introduction amount of the phosphate group is 0.1 mmol/g or more, the dispersibility can be easily improved, and when it is 0.5 mmol/g or more, the electronic repulsion can be made stronger. , it becomes easier to stably maintain the dispersed state. On the other hand, if the phosphate group content exceeds 3.0 mmol/g, there is a concern that the crystallinity will be lowered or the polymer will be dissolved, making it difficult to exhibit the desired viscosity, and the cost of introducing the sulfo group tends to increase.

The amount of phosphate groups introduced into the phosphorylated fine cellulose fibers can be evaluated by measuring the electrical conductivity as in Examples described later.

The evaluation method such as the method for measuring the average fiber width of the phosphorylated fine cellulose fibers is measured or calculated in the same manner as when the functional group is a sulfo group.

(Method for producing phosphorylated fine cellulose fibers)
Next, a method for producing phosphorylated fine cellulose fibers will be described.
In the following manufacturing method, the phosphorylated pulp manufactured by the phosphorylated pulp manufacturing method can be manufactured by subjecting it to a micronization treatment, but the manufacturing method is not limited thereto.

A phosphate esterification reaction can be used to introduce phosphoric acid groups into pulp, which is a fiber raw material. For example, ammonium dihydrogen phosphate-phosphorylating agent/urea-catalyst is brought into contact with the fiber raw material in water, and the mixture is heated at 120.degree. C. to 180.degree. For the specific operation of this phosphorylation reaction, see, for example, Yuichi Noguchi, Ikue Homma and Yusuke Matsubara, Cellulose, 24, 1295-1305 (2017).

(Phosphorylating agent)
When a compound having a phosphoric acid-derived group is used as the compound that reacts with the fiber raw material, it is not particularly limited, but it consists of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, or salts or esters thereof. At least one selected from the group. Among these, compounds having a phosphoric acid group are preferable because they are low in cost and easy to handle, but they are not particularly limited.

The compound having a phosphate group is not particularly limited.
Examples thereof include phosphoric acid and lithium salts of phosphoric acid such as lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate.
Examples include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate, which are sodium salts of phosphoric acid.
Examples include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate, which are potassium salts of phosphoric acid.
Examples include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate, which are ammonium salts of phosphoric acid.
Among these, phosphoric acid, sodium phosphoric acid, potassium phosphoric acid, and ammonium phosphoric acid are preferable from the viewpoint of high efficiency of introduction of a phosphoric acid group and ease of industrial application. More preferred are sodium dihydrogen phosphate, disodium hydrogen phosphate and ammonium dihydrogen phosphate. More preferred is ammonium dihydrogen phosphate.

(Phosphate group introduction step)
A heating method is preferred in order to promote the reaction during the introduction of the phosphate group into the fiber raw material.
The heat treatment temperature for introducing the phosphate group is not particularly limited. For example, it is preferable that the temperature range is such that thermal decomposition or hydrolysis of the fiber raw material is unlikely to occur. In particular, when a fiber raw material containing cellulose is selected as the fiber raw material, the temperature is preferably 250° C. or less from the viewpoint of the thermal decomposition temperature. Further, from the viewpoint of suppressing hydrolysis of cellulose, heat treatment at 100 to 180° C. is preferable.
The heat treatment time is desirably short from the viewpoint of suppressing thermal decomposition, hydrolysis, etc. of the fiber raw material and from the viewpoint of production efficiency. For example, the heat treatment time is set to 2 hours or less.

(carboxylated fine cellulose fiber)
In the following, the case of anionic fine cellulose fibers in which some of the hydroxyl groups of cellulose are substituted with carboxy groups will be described as a representative.
The anionic fine cellulose fibers substituted with carboxy groups are referred to as carboxylated fine cellulose fibers.

The amount of phosphate groups introduced into the carboxylated fine cellulose fibers is not particularly limited.
For example, the amount of carboxyl groups introduced per 1 g (mass) of carboxylated fine cellulose fibers is 0.1 mmol/g to 3.0 mmol/g. More preferably, it is 0.1 mmol/g or more and 2.5 mmol/g or less, and still more preferably 0.1 mmol/g or more and 2.0 mmol/g or less.
Moreover, the lower limit is preferably 0.3 mmol/g or more. It is more preferably 0.4 mmol/g or more, still more preferably 1.0 mmol/g or more.

When the amount of carboxyl groups introduced per 1 g (mass) of carboxylated fine cellulose fibers is less than 0.1 mmol/g, hydrogen bonding between fibers is strong, and dispersibility tends to decrease. Conversely, when the amount of the carboxyl group introduced is 0.1 mmol/g or more, the dispersibility can be easily improved, and when the amount is 0.5 mmol/g or more, the electronic repulsion can be strengthened. It becomes easier to stably maintain the dispersed state. On the other hand, if the carboxyl group content exceeds 3.0 mmol/g, there is a concern that the crystallinity may be lowered or the polymer may be dissolved, making it difficult to exhibit the desired viscosity, and the cost of introducing the sulfo group tends to increase.

The amount of carboxyl groups introduced into the carboxylated fine cellulose fibers can be evaluated by measuring electrical conductivity as in Examples described later.

The evaluation method such as the method for measuring the average fiber width of the carboxylated fine cellulose fibers is measured or calculated in the same manner as when the functional group is a sulfo group.

(Method for producing carboxylated fine cellulose fibers)
Next, a method for producing carboxylated fine cellulose fibers will be described.
In the following manufacturing method, the carboxylated pulp manufactured by the carboxylated pulp manufacturing method can be manufactured by subjecting the carboxylated pulp to a micronization treatment, but the manufacturing method is not limited thereto.

A TEMPO oxidation catalytic reaction can be employed to introduce carboxyl groups into pulp, which is a fiber raw material. Specifically, TEMPO (or its derivative)-catalyst/sodium bromide-oxidizing agent/sodium hypochlorite-oxidizing agent is brought into contact with the fiber raw material in water, and the carboxyl group is removed by reacting at room temperature. can be introduced.
For the specific operation of this TEMPO oxidation catalytic reaction, see, for example, Tsuguyuki Saito, Satoshi Kimura, Yoshiharu Nishiyama and Akira Isogai, Biomacromolecules, 8 (8), 2485-2491 (2007).

(TEMPO oxidation catalyst)
A derivative having a molecular skeleton of 2,2,6,6-tetramethyl-1-piperidine-N-oxyl is used as the TEMPO oxidation catalyst for oxidizing the fiber raw material. As this derivative, for example, a compound generating 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine-N-oxy radical is preferable.

(Promoting agent)
As the bromide or iodide used for oxidizing the fiber raw material, a compound that can be dissociated and ionized in water, such as an alkali metal bromide or an alkali metal iodide, can be used. The amount of bromide or iodide to be used may be appropriately selected within a range capable of promoting the oxidation reaction.

(Oxidant)
The oxidizing agent used for oxidizing the fiber raw material is an oxidizing agent capable of promoting the desired oxidation reaction, such as halogen, hypohalous acid, halogenous acid, perhalogen acid or salts thereof, halogen oxides, and peroxides. If there is, it is not particularly limited. From the viewpoint of production costs, sodium hypochlorite, which is generally used in industrial processes and is inexpensive and has a low environmental impact, is preferable.

The TEMPO oxidation catalytic reaction allows the oxidation reaction of the fiber raw material to proceed smoothly and efficiently even under mild conditions. Therefore, the reaction temperature may be room temperature of about 15 to 30°C. Since carboxyl groups are generated in the cellulose as the reaction progresses, the pH of the reaction solution decreases. Therefore, in order to allow the oxidation reaction to proceed efficiently, it is desirable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution at about 9-12, preferably about 10-11.
The end point of the reaction is desirably carried out until no decrease in pH is observed. On the other hand, if the fiber raw material is contacted with the alkaline solution for a long period of time, the fibers may be decomposed into short fibers, and the production efficiency is lowered. Therefore, the reaction time is preferably within 2 hours.

In this specification, the above-described sulfonated pulp, phosphorylated pulp, and carboxylated pulp are referred to as anionic pulp (unless otherwise specified, chemically modified pulp refers to this anionic pulp).

(TI value of anionic fine cellulose fibers)
The anionic fine cellulose fibers preferably have a predetermined thixotropic index (TI value) in addition to the viscosity described above.

By having the anionic fine cellulose fibers have a predetermined TI value, dripping of the liquid to which the fine cellulose fiber-containing solvent has been added can be more appropriately suppressed. Specifically, if the liquid to which the fine cellulose fiber-containing solvent is added is applied to the object, the state of adhering to the surface of the object can be maintained for a longer period of time. Then, the function of this liquid (function based on the functional composition) can be exhibited more appropriately.

The TI value of the anionic fine cellulose fibers is obtained by using a B-type viscometer obtained from the following formula (1) in a state of being dispersed in pure water so that the solid content concentration is 0.3% by mass to 1.0% by mass. measured using
For example, the TI value of the anionic fine cellulose fibers is preferably 4.0 or more according to the following formula (1). More preferably 4.0 to 10, still more preferably 4.0 to 8.0, even more preferably 5.0 to 8.0.

Thixotropic index (TI value) = (viscosity at 20°C and rotation speed of 6 rpm)/(20°C and viscosity at rotation speed of 60 rpm) (1)

If the anionic fine cellulose fibers have a TI value within the above range, the following advantages in terms of handleability can be obtained when applying a liquid to which a fine cellulose fiber-containing solvent is added to an object.

For example, an anionic fine cellulose fiber with a TI value in the above range maintains high viscosity when the acting shear stress (external force in this specification) is small, as shown in the above formula (1). , has the property of maintaining a low viscosity as the external force increases.
For this reason, when applying the above-mentioned liquid to an object, if an application method using a device or the like that changes the form of the liquid is adopted, problems with the device can be prevented. For example, this applies to the case of using a sprayer or the like that atomizes a liquid and applies it to an object. A sprayer includes a liquid storage section that stores liquid, a discharge section that discharges liquid in the form of a mist, and a flow path that connects the two. When the sprayer is operated, the liquid contained in the liquid containing portion passes through the flow path and is sprayed in the form of a mist from the discharge portion.

Here, conventionally, liquids such as pesticides contain a spreading agent to give them viscosity. However, the conventional technology has the problem that it is difficult to control the viscosity of such a liquid. For example, when the liquid as described above is put into a sprayer and used, problems such as clogging of the flow path in the sprayer and clogging of the opening at the tip of the discharge occur.

However, anionic fine cellulose fibers can exhibit a given TI value as described above. Therefore, if a liquid containing a fine cellulose fiber-containing solvent containing anionic fine cellulose fibers is added to a sprayer and used, an external force is applied when the liquid stored in the liquid storage part is sucked into the flow path. As a result, the viscosity of the liquid drops sharply.
In other words, the state of high viscosity (that is, a liquid state with low fluidity) existing in the container can be completely changed to a state of low fluidity like water.
Then, it is possible to move from the containing portion of the sprayer to the tip opening of the discharge portion with the same properties as water. Then, the liquid stored in the storage portion of the sprayer can be discharged in the form of mist from the tip opening. At this time, the liquid discharged from the tip opening of the ejection part of the atomizer reaches the surface of the object while being in the form of droplets before reaching the object. Then, when it reaches the surface of the object, the external force decreases, so the viscosity increases again, and the state of adhering to the surface of the object is maintained.

(Surfactant)
The fine cellulose fiber-containing solvent may contain a surfactant.
By containing a surfactant, the wettability of the fine cellulose fiber-containing solvent can be further improved.

The content ratio of the surfactant is not particularly limited.
For example, the surfactant is contained so as to be 0.1% by mass to 5.0% by mass when the fine cellulose fiber-containing solvent is added to the liquid described above. The content of the surfactant is preferably 0.1% by mass to 2.0% by mass, more preferably 0.1% by mass to 1.0% by mass, and still more preferably 0.1% by mass to 0.1% by mass. 0.5 mass %.

The type of surfactant is not particularly limited.
Components used as general surfactants such as cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic surfactants can be used. One type of surfactant may be used, or two or more types may be used in combination.

When the fine cellulose fiber-containing solvent contains a surfactant, it is preferable to adjust the viscosity of the fine cellulose fiber-containing solvent within a predetermined range.
The viscosity of this fine cellulose fiber-containing solvent is such that the surfactant is 0.5% by mass and the anionic fine cellulose fiber is dispersed in pure water so that the solid content concentration is 0.3% to 1.0% by mass. In the state, it is measured using a B-type viscometer.
For example, the B-type viscosity of the fine cellulose fiber-containing solvent (20° C., rotation speed 6 rpm, 3 minutes) is preferably 1000 mPa·s or more and 20000 mPa·s or less. It is more preferably 1000 mPa·s to 25000 mPa·s, still more preferably 9000 mPa·s to 25000 mPa·s, still more preferably 9000 mPa·s to 20000 mPa·s.

If the fine cellulose fiber-containing solvent contains a surfactant and has a viscosity within the above range, the wettability of the liquid to which the fine cellulose fiber-containing solvent is added is further improved, and the liquid drips appropriately. can be suppressed to In other words, it is possible to exhibit excellent wettability while preventing dripping that occurs in conventional spreading agents containing surfactants.

Moreover, it is preferable to adjust the TI value of the fine cellulose fiber-containing solvent to a predetermined range by including a surfactant in the fine cellulose fiber-containing solvent.
The TI value of this fine cellulose fiber-containing solvent is dispersed in pure water so that the surfactant is 0.5% by mass and the solid content concentration of the anionic fine cellulose fiber is 0.3% to 1.0% by mass. In this state, the viscosity is measured using a Brookfield viscometer obtained from the above formula (1).
For example, the TI value of the fine cellulose fiber-containing solvent is preferably 4.0 or more and 8.0 or less. More preferably 4.5 to 8.0, still more preferably 5.0 to 8.0.

If the fine cellulose fiber-containing solvent contains a surfactant and has a TI value within the above range, aggregation of the fine cellulose fibers can be suppressed regardless of the presence of the surfactant. Therefore, a predetermined viscosity can be exhibited appropriately. Therefore, even if a surfactant is contained, there is an advantage that dripping can be more appropriately prevented.

(Application liquid of the present embodiment)
The application liquid of the present embodiment (hereinafter simply referred to as application liquid) is a liquid to which the fine cellulose fiber-containing solvent is added. Specifically, the application liquid is a liquid containing water, a functional composition, and a fine cellulose fiber-containing solvent. That is, the application liquid is a liquid containing at least water, the functional composition, and the anionic fine cellulose fibers.

The functional composition contained in the application liquid is not particularly limited as long as it is a composition having a desired function.
For example, as described above, when the subject is agricultural crops, the functional composition can be agricultural chemicals such as insecticides, fungicides, plant growth regulators, and germination inhibitors, fertilizers, soil fertilizers, and the like. In addition, when the subject is an animal such as a livestock or a pet animal, a disinfectant or the like can be used as the functional composition. Furthermore, when the subject is river water, agricultural water, or the like, a fungicide or the like can be used as the functional composition.

The application liquid exhibits excellent wettability even in the form of droplets by containing the anionic fine cellulose fibers at a predetermined concentration.
For example, the application liquid contains anionic fine cellulose fibers so that the solid content concentration is 0.3% by mass to 1.0% by mass. The content is preferably 0.3% by mass or more and 0.8% by mass or less, more preferably 0.3% by mass or more and 0.7% by mass or less, and still more preferably 0.5% by mass. Above, it is below 0.7 mass %.

On the other hand, if the content of the anionic fine cellulose fibers is less than 0.3% by mass, the wettability of the applied liquid to the target object will be reduced. On the other hand, when the content of the anionic fine cellulose fibers is more than 1.0% by mass, it tends to be difficult to handle, for example, the stirring time during mixing increases.

The wettability of the liquid to be applied is evaluated by the method described in the examples below, similar to the description of the fine cellulose fiber-containing solvent.

This application liquid contains an anionic fine Contains cellulose fibers. That is, the viscosity of the application liquid can be adjusted based on the anionic fine cellulose fibers it contains.
When the application liquid has a viscosity within the above range, the application liquid can be maintained in a state of adhering to the object. In other words, it is possible to appropriately suppress dripping when the application liquid is applied to the object.

The viscosity of this application liquid is preferably 1000 mPa·s to 25000 mPa·s. It is more preferably 1000 mPa·s to 20000 mPa·s, still more preferably 1000 mPa·s to 10000 mPa·s.

On the other hand, if the viscosity is lower than 1000 mPa·s, fluidity is high and the liquid tends to drip. On the other hand, if the viscosity is higher than 50000 mPa·s, clogging is likely to occur in a device having a flow path, resulting in poor handleability.

The sagging of the applied liquid can be evaluated by the method described in the examples below, in the same manner as the fine cellulose fiber-containing solvent.

In particular, the application liquid preferably contains anionic fine cellulose fibers so that the TI value measured using a Brookfield viscometer obtained from the formula (1) is 4.0 or more. The TI value of this application liquid can be adjusted based on the anionic fine cellulose fibers it contains as described above.
When this liquid to be applied has a TI value within the above range, it is possible to improve the handleability in the same manner as in the case of the fine cellulose fiber-containing solvent described above.

The TI value of this application liquid is preferably 4.0 to 8.0. More preferably 4.0 to 7.6, still more preferably 5.0 to 7.6.

The application liquid may contain surfactants.
The wettability of the application liquid can be further improved by containing the surfactant in the application liquid.

The content of the surfactant is not particularly limited as long as the viscosity of the application liquid is not rapidly lowered.
For example, the surfactant content is preferably 0.1% by mass to 10% by mass. It is more preferably 0.1% by mass to 5% by mass, still more preferably 0.1% by mass to 1% by mass, and even more preferably 0.1% by mass to 0.5% by mass.

The type of surfactant is not particularly limited. The same ingredients as in the fine cellulose fiber-containing solvent described above can be employed.

When the application liquid contains a surfactant, it is desirable to adjust its viscosity and TI value within the following ranges. By preparing to fall within this range, it is possible to appropriately maintain the liquid dripping suppression and handleability described above.
In addition, the viscosity and TI value in the application liquid can be adjusted based on the anionic fine cellulose fibers contained.

For example, the viscosity of the application liquid containing the surfactant is measured using a Brookfield viscometer in the same manner as described above. For example, the B-type viscosity (20° C., rotation speed 6 rpm, 3 minutes) of this application liquid is preferably 1000 mPa·s or more and 50000 mPa·s or less. It is more preferably 1000 mPa·s to 25000 mPa·s, still more preferably 9000 mPa·s to 25000 mPa·s, and even more preferably 9000 mPa·s to 20000 mPa·s.

Also, for example, the TI value of the application liquid containing the surfactant is calculated from the above formula (1) in the same manner as described above. For example, the TI value of this application liquid is preferably 4.0 or more and 8.0 or less. It is more preferably 4.0 to 7.8, even more preferably 4.0 to 7.6, even more preferably 4.5 to 7.6.

(Application liquid preparation method of the present embodiment)
The application liquid preparation method of the present embodiment is a method for preparing the application liquid described above.
Specifically, in the application liquid preparation method of the present embodiment, by adjusting the solid content concentration of the anionic fine cellulose fibers in the application liquid to be within the above range, the viscosity and TI value of the application liquid are adjusted to predetermined values. Adjust within range.

By adjusting the concentration of the anionic fine cellulose fibers to a predetermined concentration, the liquid to be applied exhibits excellent wettability after being applied to an object, and the liquid to be applied suppresses dripping. be able to.
Therefore, the function of the applied liquid can be exhibited appropriately. For example, if it is prepared so as to contain a functional composition such as an agricultural chemical, the effect of this functional composition can be exhibited appropriately.

Next, the present invention will be described in more detail with reference to examples. However, the present invention is in no way limited by the following examples. In addition, unless otherwise indicated, % shows the mass %.

(Experiment 1)
In Experiment 1, the fine cellulose fiber-containing solvent of the present invention and the anionic fine cellulose fibers used in the application liquid of the present invention were prepared, and their properties were evaluated. From the results of using a water-soluble cellulose derivative (for example, hydroxypropyl cellulose (HPC)) as a material for comparison, it was confirmed that the anionic fine cellulose fiber used in the present invention is a material suitable as a spreading agent. Confirmed from the viewpoint of viscosity and sprayability.

<Preparation of sulfonated fine cellulose fiber dispersion>
First, sulfonated fine cellulose fiber dispersions (samples α-1, α-2, α-3) containing sulfonated fine cellulose fibers introduced with sulfo groups as functional groups of the anionic fine cellulose fibers were prepared as follows. prepared.

(fiber raw material)
Softwood bleached kraft pulp (NBKP) manufactured by Marusumi Paper Co., Ltd. was used as a fiber raw material. The NBKP used had a freeness of 720 mL, an average fiber length of 2.57 mm, and was not beaten. Below, the NBKP used in the experiment will be simply described as pulp.

The pulp is washed on a stainless steel sieve with an opening of 75 μm (200 mesh) using pure water (pH 5.0 to 8.0, electrical conductivity 1.0 to 1.5 μS / cm) manufactured by Marusumi Paper Co., Ltd. After that, water was drained, and the pulp adjusted to a solid content concentration of 25.0% by mass was subjected to the experiment. This pulp is wet pulp that has never been dried.
For example, 400 g of wet pulp (hereinafter referred to as wet pulp) used in the experiment contained 100 g of pulp in terms of solid mass.

The “solid mass (g)” of pulp refers to the dry mass of the pulp itself to be measured.
The weight of the dry pulp was measured by drying at 105° C. for 2 hours using a drier until the moisture content reached equilibrium.
The method of evaluating the equilibrium state in the experiment is to set the temperature of the constant temperature bath to a predetermined temperature (e.g., 50 ° C. or 105 ° C.) in the above dryer for 1 hour, and then measure the weight twice in succession. A state in which the amount of change was within 1% of the weight at the start of drying was considered to be in an equilibrium state (however, the second weight measurement was made to be at least half the drying time required for the first time).
The measurement of moisture content was calculated by the following formula.

Moisture content (%) = 100 - (solid mass of pulp (g)/pulp mass (g) at moisture content measurement) x 100

The degree of washing was determined by confirming that the electrical conductivity of the pulp filtrate was 20 μS/cm or less.
For the electrical conductivity measurement, a water quality meter (manufactured by Toa DKK Co., model number: MM-43X) connected to an electrical conductivity electrode (manufactured by Toa DKK Co., Ltd., model number: CT-58101B) was used. The reliability of the electrical conductivity value was confirmed using an electrical conductivity standard solution (12.9 mS/cm, manufactured by HORIBA).

(Chemical treatment process)
A chemically modified pulp was prepared by substituting hydroxyl groups of cellulose in fiber raw materials with anionic functional groups by performing the following chemical treatment steps.

In the experiments, a sulfo group was used as an anionic functional group.
First, the wet pulp was put into a container containing the reaction liquid, and the pulp was impregnated with the reaction liquid. This step corresponds to the "contact step" in the "chemical treatment step" of the present embodiment.

(Preparation of reaction solution)
A reaction solution was prepared as follows.
Put 600 mL of pure water in a 1 L beaker, and add sulfamic acid (purity 99.8%, manufactured by Fuso Chemical Industry Co., Ltd.) and urea (purity 99.0%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) as sulfonating agents. was added at a ratio of sulfamic acid (g)/urea (g)=70/17.5. Sulfamic acid and urea were stirred at room temperature until completely dissolved to prepare a reaction solution.

(Method of Contacting Reaction Liquid with Pulp)
400 g of wet pulp was added to the prepared reaction solution and impregnated for about 10 minutes.

The pulp impregnated with the reaction liquid is taken out from the container, spread thinly and uniformly, and dried in a dryer (manufactured by Yamato Scientific Co., Ltd., model number: DKN602) under an atmosphere of 80 ° C. to obtain the reaction liquid-impregnated pulp impregnated with the reaction liquid. prepared.

The step of drying the pulp impregnated with the reaction solution corresponds to the drying step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.

(heating reaction)
Next, the prepared reaction solution-impregnated pulp was subjected to the heating reaction step of the next step, and heat reaction was performed to prepare sulfonated pulp (reacted pulp constituting sulfamic acid/urea treated pulp).
The moisture content of the supplied reaction liquid-impregnated pulp was 5% or less.

The above heating reaction corresponds to the reaction step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.

The reaction conditions were as follows.
A dryer (manufactured by Yamato Scientific Co., model number: DKN602) was used for heating.
Dryer constant temperature bath temperature: 140°C, heating time: 30 minutes

The temperature of the reaction conditions in the above heating reaction corresponds to the reaction temperature in the reaction step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.
The heating time of the reaction conditions in the above heating reaction corresponds to the reaction time of the reaction step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.

After the heat reaction, the reacted pulp was suspended in pure water and neutralized with sodium bicarbonate until no bubbles were generated. The neutralized pulp was washed with pure water on a stainless steel sieve (300 mesh) with an opening of 46 μm until it became neutral.
The degree of washing was determined by confirming that the electric conductivity of the pulp filtrate was 50 μS/cm or less. The above water quality meter was used for the electrical conductivity measurement.

The step of washing the reacted pulp with pure water until it becomes neutral corresponds to the washing step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.

(Measurement of solid content concentration of sulfonated pulp)
In order to prepare fine cellulose fibers having a predetermined solid content concentration in the next step of micronization, the solid content concentration (% by mass) of the sulfonated pulp containing moisture was measured.
The sulfonated pulp after the washing step was fractionated and the mass was weighed with an electronic balance (the mass at this time is defined as the mass fractionated when measuring the solid content concentration in the following formula).
The sample was dried in a dryer set at 105 ° C. for 2 hours or more and the mass when it reached a constant weight was weighed with an electronic balance (the mass at this time was the mass after drying in the following formula), and the following formula was used. was used to calculate the solid content concentration.

Solid content concentration of sulfonated pulp (mass%) = (mass of solid content after drying (g))/(mass (g) fractionated when measuring solid content concentration) x 100

(Miniaturization process)
Next, the sulfonated pulp prepared by the chemical treatment step was subjected to the next micronization step to prepare sulfonated fine cellulose fibers.

First, sulfonated pulp and pure water were mixed to prepare a pulp slurry adjusted to a solid content concentration of 1.0% by mass of sulfonated pulp. That is, this pulp slurry is prepared so that the composition ratio of sulfonated pulp and pure water is 99.0 parts by mass of pure water per 1.0 part by mass of sulfonated pulp (solid content mass (g)). It is what was done.

Next, this pulp slurry was subjected to a high-pressure homogenizer (conditions below) to prepare a dispersion containing fine cellulose fibers (sulfonated fine cellulose fibers) (sulfonated fine cellulose fiber dispersion). The prepared sulfonated fine cellulose fiber dispersion had a composition ratio of sulfonated fine cellulose fibers and pure water of 99% pure water per 1.0 part by mass of sulfonated fine cellulose fibers (solid content mass (g)). .0 parts by mass. That is, the sulfonated fine cellulose fiber dispersion is prepared so that the solid concentration of the sulfonated fine cellulose fibers is 1.0% by mass.

The conditions for the refinement process are shown below.
The pulp slurry adjusted to 1.0% by mass was subjected to a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd., product name: NanoVater, model number: L-ES008-D10).
Processing conditions: Set pressure 60 MPa, processing times 5 times

(Measurement of solid content concentration of sulfonated fine cellulose fiber dispersion)
It was confirmed that there was no change in the solid content concentration in the dispersion before and after the micronization process.
A certain amount was taken from the prepared sulfonated fine cellulose fiber dispersion, and the mass was weighed with an electronic balance (the mass at this time is defined as the mass taken when measuring the solid content concentration in the following formula).
The sample was dried in a dryer set at 105 ° C. for 2 hours or more and the mass when it reached a constant weight was weighed with an electronic balance (the mass at this time was the mass after drying in the following formula), and the following formula was used. to calculate the solid content concentration.
The solid content concentration of the fine cellulose fibers of the present embodiment is a value calculated according to the dilution ratio when the known solid content concentration calculated in this measurement is diluted.

Solid content concentration (mass%) of the sulfonated fine cellulose fiber dispersion = (solid content mass (g) after drying)/(mass (g) fractionated during solid content concentration measurement) x 100

The physical properties of the prepared sulfonated fine cellulose fiber dispersion were evaluated by the following measurement methods.

(Measurement of sulfur introduction amount by electrical conductivity measurement)
The amount of sulfur introduced due to sulfo groups in the sulfonated fine cellulose fibers was measured by titration with an aqueous sodium hydroxide solution after treating the prepared sulfonated fine cellulose fibers with an ion exchange resin.
In the ion-exchange resin treatment, a strongly acidic ion-exchange resin (Amberjet 1024, manufactured by Organo Co., Ltd.; conditioned) was added to 100 g of a slurry containing sulfonated fine cellulose fibers adjusted to 0.2% by mass, and the mixture was stirred for 1 hour. gone. After that, it was poured onto a mesh with an opening of 200 μm to separate the resin and the slurry.

In the titration using alkali, a slurry containing sulfonated fine cellulose fibers after treatment with an ion-exchange resin was added with a 0.1 M sodium hydroxide aqueous solution or a 1.0 M sodium hydroxide aqueous solution (both manufactured by Fujifilm Wako Pure Chemical Industries, model number for volumetric analysis) is added at a time of 10 μL to 50 μL, and the change in the electrical conductivity value is measured, and the electrical conductivity is plotted on the vertical axis and the sodium hydroxide titration amount on the horizontal axis to obtain a curve, An inflection point was confirmed from the obtained curve.
The titration amount of sodium hydroxide at this inflection point corresponds to the amount of sulfo groups. Therefore, the amount of sulfo groups introduced into the sulfonated fine cellulose fibers was measured by dividing the amount of sodium hydroxide at this inflection point by the amount of solids contained in the sulfonated fine cellulose fibers used for measurement.
Electrical conductivity was measured using a water quality meter connected to the electrical conductivity electrode described above. The reliability of the electrical conductivity value was confirmed using an electrical conductivity standard solution (12.9 mS/cm, manufactured by HORIBA) in the same manner as described above.

Specifically, the amount of sulfo group introduced was measured by the following operation.
In a 200 mL glass beaker, 75 g of a slurry containing 0.2 mass % sulfonated fine cellulose fibers separated from the ion exchange resin was prepared, and an electrical conductivity electrode was immersed in the slurry while stirring at 400 rpm. After the electrical conductivity was stabilized, 10 to 50 μL of 0.1 M sodium hydroxide aqueous solution or 1.0 M sodium hydroxide aqueous solution was added dropwise using a micropipette. At the start of dropping, the slurry is acidic, and the protons of the sulfo group and sodium hydroxide are neutralized to shift the slurry to basic. The point at which the solution became neutral was the inflection point, and the amount of sodium hydroxide added up to the inflection point was determined.
After that, the amount of sodium hydroxide (mmol) added up to the inflection point was divided by 0.150 g, which is the solid mass of the slurry containing sulfonated fine cellulose fibers used for measurement, to obtain the amount of sulfo groups (mmol/ g) was obtained.

As an example, the amount of sulfo groups is calculated as follows from the electrical conductivity measurement (shown in FIG. 2) of sample α-2 obtained by the method described below. In FIG. 2, the inflection points of the graph are indicated by dashed lines.
Amount of sodium hydroxide added up to the inflection point: 0.15 mmol
Cellulose solid content mass in measurement sample: 0.150 g
Amount of sulfo group: 1.00 mmol/g

(Measurement of total light transmittance and haze value of sulfonated fine cellulose fiber dispersion)
To evaluate the transparency of the sulfonated fine cellulose fiber dispersion, the total light transmittance and haze value were measured using a haze meter.
A predetermined amount of the sulfonated fine cellulose fiber dispersion diluted and mixed with pure water to 0.5% by mass was collected, and the measured solution thus collected was measured using a spectroscopic haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model number: SH-7000, Ver 2.00.02), and the total light transmittance and haze value were measured as follows. In addition, the measuring method was performed based on the method of JISK7105.

An optional glass cell (part number: 2277, square cell, optical path length 10 mm×width 40×height 55) of the spectroscopic haze meter filled with pure water was used as a blank measurement value, and the light transmittance of the measurement solution was measured. The light source was D65, the field of view was 10°, and the measurement wavelength range was 380 to 780 nm.
The total light transmittance (%) and the haze value (%) were calculated using the numerical values obtained from the control unit of the spectroscopic haze meter (model number CUII, Ver2.00.02).

(B-type viscosity measurement of sulfonated fine cellulose fiber dispersion)
A 1.0% by mass sulfonated fine cellulose fiber dispersion or a 0.5% by mass diluted sulfonated fine cellulose fiber dispersion with pure water was added to a screw tube (manufactured by SANYO, model number: 84-0741/No. 8). It was placed in a container and allowed to stand for 24 hours.
Measurement was performed using a Brookfield viscometer (manufactured by Brookfield, model number: DV2T (RV type), spindle No. 6).

The conditions and the like for viscosity measurement are shown below.
The B-type viscometer used was manufactured by Eiko Seiki Co., Ltd. (model number: DV2T).
Measurement conditions: rotation speed 6 rpm, measurement temperature 20° C., measurement time 3 minutes, spindle No. 6. Single point data recording method Single point is a recording method setting item that acquires only the value at the end of the measurement in the Brookfield viscometer used in this experiment. In other words, the instantaneous value after 3 minutes from the start of measurement is recorded.

(Sprayability test of sulfonated fine cellulose fiber dispersion)
The sprayability test was evaluated by the test method described in Experiment 3 below.

<Sample α-2>
For sample α-2, a sulfonated fine cellulose fiber dispersion was prepared in the same manner as α-1, except that a reaction solution prepared under the conditions of sulfamic acid (g)/urea (g) = 70/35 was used. made an evaluation.

(fiber raw material)
As a fiber raw material, a softwood kraft pulp (NBKP) sheet (average fiber length: 2.6 mm) manufactured by Marusumi Paper Co., Ltd. was dried at 105° C. and adjusted to a moisture content of 10%. Hereinafter, the fiber raw material used in the experiment is simply referred to as pulp.

(Chemical treatment process)
In the experiment, a chemically modified pulp in which the hydroxyl groups of cellulose in the fiber raw material were substituted with anionic functional groups was obtained by performing the following chemical treatment steps.
In the experiment, a sulfo group was used as an anionic functional group as in sample α-1.

(Preparation of reaction solution)
A reaction solution was prepared as follows.
A reaction solution was prepared by mixing sulfamic acid (purity 98.5%, manufactured by Fuso Chemical Industries, Ltd.) and urea (purity 99%, manufactured by Wako Pure Chemical Industries, model number; special grade reagent).

An example of the method for preparing the reaction solution is shown below.
Both were mixed so that the concentration ratio (g/L) was 1:1.4.
For example, 100 g of sulfamic acid, 144 g of urea, and 366 ml of pure water are added to a 1 L beaker, and the sulfamic acid and urea create a reaction solution with a sulfamic acid/urea ratio ((g/L)/(g/L))=273/393. prepared. This reaction solution contains 144 parts by mass of urea per 100 parts by mass of sulfamic acid.

(Method of Contacting Reaction Liquid with Pulp)
Pulp was added to the prepared reaction solution to prepare a slurry. This slurry was prepared so that the ratio of pulp (solid content mass) to reaction liquid was pulp:chemical=1:1.2.
For example, in the case of a reaction liquid having a sulfamic acid/urea ratio ((g/L)/(g/L)) of 273/393, 3.0 g of the reaction liquid is added to 1.0 g of pulp to The pulp was impregnated. At this time, in order to uniformly impregnate the pulp with the reaction solution, the prepared slurry was kneaded by hand for 30 minutes. After 30 minutes, the pulp impregnated with the reaction liquid was suction-filtered until no more water droplets fell, to prepare pulp impregnated with the reaction liquid (reaction liquid-impregnated pulp).

(Drying process)
Then, the reaction solution-impregnated pulp after suction filtration was dried using a dryer (manufactured by Isuzu Manufacturing Co., Ltd., model number: VTR-115, 105° C.). Drying was carried out until the moisture content of the pulp reached equilibrium. The moisture content of the reaction liquid-impregnated pulp after drying was 5% or less. The moisture content was measured in the same manner as for sample α-1.

The step of drying the reaction liquid-impregnated pulp corresponds to the drying step in the chemical treatment step of the method for producing sulfonated fine cellulose fibers of the present embodiment.

(heating reaction)
Next, the prepared reaction solution-impregnated pulp was subjected to the next heating reaction step to carry out a heating reaction to prepare a sulfonated pulp.

The reaction conditions were as follows.
A dryer (manufactured by Isuzu Manufacturing Co., Ltd., model number: VTR-115) was used for the heating reaction.
Thermostatic bath temperature: 140°C, heating time: 30 minutes

After the heat reaction, neutralization was performed in the same manner as sample α-1 to prepare sulfonated pulp (sulfamic acid/urea treated pulp).

(Measurement of solid content concentration of sulfonated pulp)
The solid content concentration (% by mass) of the sulfonated pulp containing moisture was measured in the same manner as for sample α-1.

In the micronization step, sulfonated pulp and pure water were mixed in the same manner as in sample α-1 to prepare a pulp slurry, and then, in the same manner as in sample α-1, a high-pressure homogenizer (a homogenizer manufactured by Kosunijuuichi Co., Ltd., model number ;N2000-2C-045 type) to prepare a sulfonated fine cellulose fiber dispersion.

The conditions for the refinement process are shown below.
Treatment conditions: 2 times at a set pressure of 10 MPa, 1 time at a set pressure of 50 MPa, 5 times at a set pressure of 60 MPa

The amount of sulfur introduced into the sulfonated fine cellulose fibers in the sulfonated fine cellulose fiber dispersion was 1.4 mmol/g.

(Measurement of sulfur introduction amount by electrical conductivity measurement)
The amount of sulfur introduced due to the sulfo groups in the sulfonated fine cellulose fibers was determined in the same manner as in sample α-1.

(Observation of fiber morphology and measurement of fiber width using SPM)
Observation of the sulfonated fine cellulose fibers was performed using an electron microscope.
A sulfonated fine cellulose fiber was prepared with pure water to a solid content concentration of 0.001 to 0.005% by mass, and a thin film was formed on a silica substrate coated with PEI (polyethyleneimine) by spin coating. Observation of the fine cellulose fibers was performed using a scanning probe microscope (manufactured by Shimadzu Corporation, model number: SPM-9700).
The fiber width and fiber length were measured by randomly selecting 20 fibers in the observed image.
The average fiber width was 30 nm or less.
The average fiber width of other fine cellulose fibers can be calculated in the same manner.

In addition, the measurement of the total light transmittance and haze value of the sulfonated fine cellulose fiber dispersion of sample α-3, the B-type viscosity measurement, and the sprayability test were performed in the same manner as for sample α-1.

<Preparation of TEMPO oxidized fine cellulose fiber dispersion>
Next, TEMPO-oxidized fine cellulose fiber dispersions (samples β-1, β-2, β-3) containing TEMPO-oxidized fine cellulose fibers into which carboxyl groups were introduced as functional groups of the anionic fine cellulose fibers were prepared as follows. Prepared as follows.

A wet pulp adjusted to a solid content concentration of 25.0% by mass shown in sample α-1 was used for the experiment as a fiber raw material.
Carboxyl groups were introduced into pulp in the presence of hypochlorite using 2,2,6,6-tetramethyl-1-piperidine-oxy radical (hereinafter referred to as TEMPO) and bromide as catalysts.

Specifically, 8 mg of TEMPO (manufactured by Alfa Aesar, model number (purity); free radical, 98+%) and sodium bromide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) were added to 500 mL of pure water in a 1 L beaker. 8 mg was added to prepare a catalyst solution.
20 g of wet pulp (5 g of solid mass) was added to the prepared catalyst solution and stirred until uniform to prepare a pulp slurry containing a catalyst component.

After adding 6.8 mL of an aqueous solution of sodium hypochlorite with an effective chlorine concentration of 11% (manufactured by Film Wako Pure Chemical Industries, model number; for chemical use) to the prepared pulp slurry, 1.0 M hydrochloric acid (manufactured by Film Wako Pure Chemical Industries, Ltd., Model number (purity); guaranteed reagent (5.0+%)) was added to adjust the pH to 10.5, and the oxidation reaction was initiated.
During the oxidation reaction, the pH decreased with time, but the pH was adjusted to 10.0 by adding a 1.0 M sodium hydroxide aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; for volumetric analysis). held at 5.

The effective chlorine concentration of the sodium hypochlorite aqueous solution was confirmed by titration with potassium iodide/sulfuric acid/sodium thiosulfate using starch as an indicator, which is generally known as a chemical experiment method.

After 2 hours from the start of the oxidation reaction, ethanol (manufactured by Wako Pure Chemical Industries, Ltd., model number; first grade reagent) was added to stop the reaction, and then washed with pure water on a stainless steel sieve (300 mesh) with an opening of 46 μm. TEMPO oxidized pulp was obtained.
The degree of washing was determined by confirming that the electric conductivity of the pulp filtrate was 60 μS/cm or less. A water quality meter similar to that for sample α-1 was used to measure electrical conductivity.

The prepared TEMPO-oxidized pulp was subjected to refining treatment under the same conditions as for sample α-1 to prepare a 1.0% by mass TEMPO-oxidized fine cellulose fiber dispersion (sample β-1).

Using sample β-1, the amount of carboxyl groups introduced (described later), the total light transmittance, the haze value, the B-type viscosity, and the sprayability test were measured. The measurement conditions and equipment were the same as those for sample α-1.

(Measurement of carboxyl group introduction amount by electrical conductivity measurement)
The amount of carboxyl groups introduced by TEMPO oxidation was measured by conducting conductivity titration with an aqueous sodium hydroxide solution after adding hydrochloric acid to the prepared 0.3% by mass TEMPO-oxidized fine cellulose fiber slurry to adjust the pH to acidic. did.

In the titration using alkali, the slurry containing TEMPO oxidized fine cellulose fibers after acidification of the slurry with hydrochloric acid was added with a 0.1 M sodium hydroxide aqueous solution or a 1.0 M sodium hydroxide aqueous solution (both manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., While adding 10 μL to 50 μL of model number for volumetric analysis), measure the change in the electrical conductivity value, plot the electrical conductivity on the vertical axis and the titration amount of sodium hydroxide on the horizontal axis to obtain a curve. , the inflection point was confirmed from the obtained curve.

The electrical conductivity was measured using the same device as for sample α-1.
Using the titration curve obtained as shown in FIG. 3, from the point (point A) where the decrease in the electric conductivity at equal intervals from the start of dropping the sodium hydroxide aqueous solution is no longer observed, the electric conductivity starts to increase at equal intervals. The titration amount of sodium hydroxide used up to the point (point B) corresponds to the amount of carboxyl groups (A and B are indicated in FIG. 3, and the amount of sodium hydroxide is indicated by a dashed line). Therefore, the amount of carboxyl groups introduced into the oxidized TEMPO fine cellulose fibers was measured by dividing the amount of sodium hydroxide in this range by the amount of solids contained in the oxidized TEMPO fine cellulose fibers used for measurement.

Specifically, the amount of carboxyl group introduced was measured by the following operation.
Prepare 72.3 g of slurry containing 0.3% by mass TEMPO oxidized fine cellulose fibers in a 200 mL glass beaker, add 300 to 400 μL of 1 M hydrochloric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent), and add pure water. and adjusted the total amount to 140 g. After stirring this solution for 1 hour, the conductivity electrode was immersed while stirring at 400 rpm. After the electrical conductivity was stabilized, 10 to 50 μL of 0.1 M sodium hydroxide aqueous solution or 1.0 M sodium hydroxide aqueous solution was added dropwise using a micropipette. At the start of dropping, the slurry is acidic, and the protons of the carboxyl group and sodium hydroxide are neutralized to shift the slurry to basic.
After that, the amount of sodium hydroxide (mmol) used from point A to point B was divided by 0.217 g, which is the solid content mass of the slurry containing TEMPO oxidized fine cellulose fibers used for measurement, to obtain the amount of carboxyl groups ( mmol/g) was obtained.

As an example, the amount of carboxyl groups is calculated as follows from the electrical conductivity measurement (shown in FIG. 3) of sample β-3 obtained by the method described below.
Amount of sodium hydroxide used from point A to point B: 0.34 mmol
Cellulose solid content mass in measurement sample: 0.217 g
Carboxyl group amount: 1.56 mol / g

<Sample β-2>
Sample β-2 was prepared and evaluated in the same manner as sample β-1, except that a reaction solution prepared under the conditions of TEMPO 23.2 (mg), sodium bromide 514 mg, and sodium hypochlorite 34 mL was used. rice field.

<Sample β-3>
Sample β-3 was prepared and evaluated in the same manner as sample β-1, except that a reaction solution prepared under the conditions of 156 mg of TEMPO, 514 mg of sodium bromide, and 34 mL of sodium hypochlorite was used.

<Preparation of phosphorylated fine cellulose fiber dispersion>
Next, phosphorylated fine cellulose fiber dispersions (Samples γ-1, γ-2, γ-3) containing phosphorylated fine cellulose fibers into which phosphoric acid groups were introduced as functional groups of the anionic fine cellulose fibers were prepared as follows. Prepared as follows.

<Sample γ-1>
As a fiber raw material, wet pulp adjusted to a solid content concentration of 25.0% by mass shown in sample α-1 was used in the experiment.
Phosphate groups were introduced into the pulp using ammonium dihydrogen phosphate and urea.

Specifically, 70 mL of pure water is placed in a 300 mL beaker, ammonium dihydrogen phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) and urea (purity 99.0%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) was added at a ratio of ammonium dihydrogen phosphate (g)/urea (g)=5.6/15.0. Ammonium dihydrogen phosphate and urea were stirred at room temperature until completely dissolved to prepare a reaction solution.

(Method of Contacting Reaction Liquid with Pulp)
40 g of wet pulp was added to the prepared reaction liquid and impregnated for about 10 minutes.

The pulp impregnated with the reaction liquid was taken out from the container and dried in the same manner as sample α-1 to prepare the reaction liquid-impregnated pulp.

(heating reaction)
Next, the prepared reaction solution-impregnated pulp was subjected to a reaction step, and subjected to a heating reaction to prepare a phosphorylated pulp.
The moisture content of the supplied reaction liquid-impregnated pulp was 5% or less.

The reaction conditions were as follows.
A dryer (same as sample α-1) was used for heating Temperature of constant temperature bath of dryer: 140°C Heating time: 11 minutes

After the heat reaction, neutralization was performed in the same manner as sample α-1 to prepare phosphorylated pulp.

Next, the phosphorylated pulp prepared by the chemical treatment step was subjected to the next step of pulverization treatment. The prepared phosphorylated pulp was subjected to refining treatment under the same conditions as for sample α-1 to prepare a 1.0% by mass phosphorylated fine cellulose fiber dispersion (γ-1).
Using the sample γ-1, the amount of phosphate group introduced (described later), the total light transmittance, the haze value, the B-type viscosity, and the sprayability test were measured. The measurement conditions and equipment were the same as those for sample α-1.

(Measurement of phosphate group introduction amount by electrical conductivity measurement)
The amount of phosphate groups introduced due to phosphate groups was measured by titration with an aqueous sodium hydroxide solution after treating the prepared phosphorylated fine cellulose fibers with an ion-exchange resin.
In the ion-exchange resin treatment, a strongly acidic ion-exchange resin (Amberjet 1024, manufactured by Organo Co., Ltd.; conditioned) was added to 100 g of a slurry containing phosphorylated fine cellulose fibers adjusted to 0.2% by mass, and the mixture was stirred for 1 hour. gone. After that, it was poured onto a mesh with an opening of 200 μm to separate the resin and the slurry.

In the titration using alkali, 0.1 M sodium hydroxide aqueous solution or 1.0 M sodium hydroxide aqueous solution (both manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number ; for volumetric analysis) was added in increments of 10 μL to 50 μL, the change in the electrical conductivity value was measured, and the electrical conductivity was plotted on the vertical axis and the sodium hydroxide titration amount on the horizontal axis to obtain a curve. An inflection point was confirmed from the curve.
The electrical conductivity was measured using the same device as for sample α-1.
The titration amount of sodium hydroxide at the obtained inflection point corresponds to the amount of phosphate groups. Therefore, the amount of phosphate groups introduced into the phosphorylated fine cellulose fibers was measured by dividing the amount of sodium hydroxide at this inflection point by the amount of solids contained in the phosphorylated fine cellulose fibers used for measurement.
A phosphate group is a divalent anionic functional group (a sulfo group is a monovalent anionic functional group). Therefore, there are two points of inflection. The amount of phosphate group introduced herein means the amount required up to the second inflection point.

Specifically, the amount of phosphate group introduced was measured by the following operation.
In a 200 mL glass beaker, 93.2 g of a slurry containing 0.2 mass % phosphorylated fine cellulose fibers separated from the ion exchange resin was prepared, and an electrical conductivity electrode was immersed in the slurry while stirring at 400 rpm. After the electrical conductivity was stabilized, 10 to 50 μL of 0.1 M sodium hydroxide aqueous solution or 1.0 M sodium hydroxide aqueous solution was added dropwise using a micropipette. At the start of dropping, the slurry is acidic, and the protons of the phosphate group and sodium hydroxide are neutralized, thereby shifting the slurry to basic. As shown in FIG. 4, the point at which the first of the two protons present in the phosphate group reaches neutrality is the first inflection point, and the second inflection point is obtained by further adding sodium hydroxide. An inflection point appears.
After that, the amount of sodium hydroxide (mmol) added up to the first inflection point was divided by 0.183 g, which is the solid content mass of the phosphorylated fine cellulose fiber-containing slurry used for measurement, to obtain the amount of phosphate groups. (mmol/g) was obtained.

As an example, the amount of phosphate groups is calculated as follows from electrical conductivity measurement (shown in FIG. 4) of sample γ-2 obtained by the method described later. In the graph of FIG. 4, dashed lines are drawn at the first inflection point and the second inflection point.
Amount of sodium hydroxide added up to the first inflection point: 0.23 mmol
Amount of sodium hydroxide added from the first inflection point to the second inflection point: 0.23 mmol
Cellulose solid content mass in measurement sample: 0.183 g
Phosphate group amount: 1.26 mmol / g

<Sample γ-2>
Sample γ-2 was prepared and evaluated in the same manner as sample γ-1, except that the pulp was reacted under the conditions that the temperature of the constant temperature bath of the dryer in the reaction process was 140 ° C. and the heating time was 30 minutes. rice field.

<Sample γ-3>
Sample γ-3 was prepared and evaluated in the same manner as sample γ-1, except that the pulp was reacted under the conditions that the temperature of the constant temperature bath of the dryer in the reaction process was 140 ° C. and the heating time was 40 minutes. gone.

<Sample δ>
A sample δ was prepared as a comparative example.
For this sample δ, hydroxypropyl cellulose (HPC, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number: 1000 to 5000 cP) was used instead of fine cellulose fibers.
Solutions were prepared as follows.
With a total mass of 100 g, 0.5 g to 3.0 g of HPC was weighed with an electronic balance, 97.0 to 99.5 g (20° C.) of pure water was added, and the mixture was stirred until completely dissolved.
Evaluation was performed as follows.
Using an HPC solution prepared at 0.5% by mass, the total light transmittance, haze value, B-type viscosity, and sprayability test were measured in the same manner as for sample α-1. Using 1.0% by mass to 3.0% by mass HPC solution, measurement of B-type viscosity and sprayability test was performed in the same manner as sample α-1.

(Results of Experiment 1)
Figure 1 shows the physical properties of each sample.
Figures 2, 3, and 4 show typical examples of conductivity titration curves of the anion-modified fine cellulose fibers, respectively.

FIG. 1 shows the results of characterization of the cellulose component used in the application liquid containing fine cellulose fibers.
It has been reported that a cellulose fine fiber dispersion prepared by introducing an anionic functional group exhibits excellent effects in terms of transparency and viscosity. First, total light transmittance and haze value were measured as the transparency of the cellulose fine fiber dispersion. The total light transmittance of the cellulose fine fiber dispersion was 99.0% or higher in all of the prepared samples. As for the haze value, as the amount of functional group introduced increased, the haze value decreased and the transparency increased as a tendency for all the prepared samples. This result agreed with the characteristics of anionic fine cellulose fiber dispersions reported so far. A water-soluble HPC aqueous solution (sample δ), which is a comparative material, also exhibited high transparency.
The anionic fine cellulose fiber dispersions exhibited high B-type viscosity values at low solids concentrations of 0.5 and 1.0 wt% solids. On the other hand, the water-soluble HPC aqueous solution (sample δ), which is a comparative material, showed a viscosity lower than 1000 mPa·s at the same solid content concentration as the anionic fine cellulose fiber dispersion. In order to exhibit a viscosity value equivalent to that of an anionic fine cellulose fiber dispersion, an aqueous solution with a solid content concentration higher than 2.0% by mass is required. However, at this solid content concentration, desirable sprayability was not obtained.

In the present invention, we envisioned a spreading agent that imparts viscosity to the pesticide spray liquid, and focused on anionic fine cellulose fibers as a new spreading agent material. Conventionally, water-soluble cellulose such as HPC has been the most advanced technology as a cellulose material used as a spreading agent material. In the present invention, the anionic fine cellulose fiber is a material that can solve these problems, and the characteristics as a spreading agent were evaluated in subsequent experiments.

(Experiment 2)
In Experiment 1, physical properties of each anionic fine cellulose fiber and HPC were confirmed. In Experiment 2, physical properties that are more important when used as a spreading agent were evaluated, and suitability as an application liquid was examined.

(Samples and reagents used in Experiment 2)
Samples α-1 to 3, β-1 to 3, and γ-1 to γ-3 prepared in Experiment 1 and having a solid concentration of 1.0% by mass were used as cellulose components. Sample δ was used as a comparative example.

As surfactant components, (A) sodium lauryl sulfate (manufactured by Tokyo Chemical Industry, model number: S0588), (B) dodecyldimethyl(3-sulfopropyl) ammonium hydroxide inner salt (manufactured by Tokyo Chemical Industry, model number: D3860) , (C) polyoxyethylene sorbitan monolaurate (manufactured by Tokyo Chemical Industry Co., Ltd., model number; T2530, Tween20), and (D) polyoxyethylene sorbitan monooleate (manufactured by Tokyo Chemical Industry Co., Ltd., model number; T2533, Tween80).

(Preparation of application liquid containing α-1)
Application liquids containing α-1 were prepared with the composition ratios shown in FIG. 7 (Examples 1 to 8, Comparative Examples 1 to 6).

In the figure, the example is indicated by S and the comparative example by C. For example, Example 1 is indicated as S-1, and Comparative Example 1 is indicated as C-1. In addition, unless otherwise specified, the same notation is used in other examples and comparative examples.

A representative example of the preparation method is shown below.

(Example 1: Application liquid containing α-1 having a solid concentration of 1.0% by mass)
Sample α-1 having a solid content concentration of 1.0% by mass was used as it was.

(Example 2: Application liquid containing diluted α-1)
60 g of sample α-1 having a solid content concentration of 1.0% by mass was weighed in a 300 mL beaker with an electronic balance, and 40 g of pure water (20° C.) was added. Stirring for 10 minutes with a stirrer (300 rpm, manufactured by AS ONE, model number: CHPS-170DF) using a stirrer (φ8 × 40), sample α-1 and pure water are uniformly mixed to obtain sulfonated fine cellulose fibers. An application liquid having a solid content concentration of 0.6% by mass was prepared.

(Example 5: Application liquid containing surfactant-blended α-1)
40 g of sample α-1 having a solid concentration of 1.0% by mass was weighed into a 300 mL beaker with an electronic balance, and 60 g of pure water (20° C.) was added. Further, 0.5 g of surfactant component (A) sodium lauryl sulfate was added, and the mixture was stirred for 10 minutes with a stirrer (300 rpm, manufactured by AS ONE, model number: CHPS-170DF) using a stirrer (φ8×40). By uniformly mixing sample α-1 in pure water and dissolving the surfactant component, the solid content concentration of the sulfonated fine cellulose fibers containing the surfactant component was applied to 0.6% by mass. A liquid was prepared.

(Preparation of application liquid containing α-2)
Application liquids containing α-2 were prepared with the composition ratios shown in FIG. 8 (Examples 9 to 16, Comparative Examples 7 to 12).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing α-3)
Application liquids containing α-3 were prepared with the composition ratios shown in FIG. 9 (Examples 9 to 16, Comparative Examples 7 to 12).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing β-1)
Application liquids containing β-1 were prepared with the composition ratios shown in FIG. 10 (Examples 29 to 38, Comparative Examples 19 to 22).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing β-2)
Application liquids containing β-2 were prepared with the composition ratios shown in FIG. 11 (Examples 39-46, Comparative Examples 23-28).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing β-3)
Application liquids containing β-3 were prepared with the composition ratios shown in FIG. 12 (Examples 47 to 54, Comparative Examples 29 to 34).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing γ-1)
Application liquids containing δ-1 were prepared with the composition ratios shown in FIG. 13 (Examples 55 to 66, Comparative Examples 35 to 36).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of Application Liquid Containing Sample γ-2)
Application liquids containing γ-2 were prepared with the composition ratios shown in FIG. 14 (Examples 67-78, Comparative Examples 37-38).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of Application Liquid Containing Sample γ-3)
Application liquids containing γ-3 were prepared with the composition ratios shown in FIG. 15 (Examples 79 to 89, Comparative Examples 39 to 41).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of application liquid containing δ)
Application liquids containing δ were prepared with the composition ratio shown in FIG. 16 (Comparative Examples 42 to 47).
The preparation method was the same as for the application liquid containing α-1.

(Preparation of Comparative Example 47)
Comparative Example 47 was pure water containing no cellulose component and no surfactant component (Fig. 16).

(Characteristic evaluation of application liquid containing fine cellulose fibers)
Using the prepared examples and comparative examples, the following property evaluations were performed.

(Measurement of viscosity)
Viscosity measurement was performed after putting 100 g of the prepared application liquid into a screw tube (manufactured by SANYO, model number: 84-0741/No. 8) and allowing it to stand for 24 hours.
Measurement was performed using a B-type viscometer (manufactured by Brookfield, model number: DV2T (RV type), spindle No. 6).

The viscosity measurement conditions were as follows.
Liquid temperature of applied liquid: 20°C
Measurement time: 3 minutes Rotation speed: Rotation speed 6 rpm and 60 rpm
Data recording method: Single point (Method of acquiring only the value 3 minutes after the start of measurement)

(Measurement of TI value)
The thixotropic index (TI value) was measured as follows.
Calculation of the TI value was carried out using the Brookfield viscometer described above, and measurements were carried out at rotation speeds of 6 rpm and 60 rpm, and the respective viscosities were calculated from the following formula. Other conditions were as described above.

TI value = (viscosity at 6 rpm)/(viscosity at 60 rpm)

(Evaluation of liquid dripping)
The dripping of the application liquid was evaluated from the sliding angle by the method of the dripping test described below.
An outline is shown in FIG.
First, an OPP film (manufactured by Nippon Paper Industries, model number: #40 30*45) is attached to one side of a plate-shaped base material (for example, a clipboard (manufactured by Lion Office, model number: No. 5)) so as not to wrinkle. An evaluation plate was produced.
Next, as shown in FIG. 5, a stand (manufactured by Shibata Kagaku, model number: 050700-1) is equipped with a double-open clamp (manufactured by Yamanaka, model number: NC-4S, product number: 1-7209-01), and this clamp The proximal end of the evaluation plate was fixed. At this time, the surface of the OPP film was directed upward, and the surface of the OPP film of the evaluation plate was adjusted to be horizontal.
This evaluation plate is attached to a stand so that the tip on the opposite side can be swung downward with the base end as a fulcrum. In other words, the evaluation plate is mounted so as to be rotatable with the proximal end as a fulcrum.
In addition, the tip portion may be supported by a jack (manufactured by ASPALAND, model number: 2019-817-06-12-06-07-05-28) so that the surface of the OPP film of the evaluation plate is stabilized.

In this evaluation method, the horizontal state of the surface of the OPP film of the evaluation plate is taken as the reference plane (the sliding angle at this time is 0°).
As shown in FIG. 5(a), a sample droplet of 0.1 g is left still on the surface of the OPP film of the evaluation plate with a sliding angle of 0°.
Next, as shown in FIGS. 5(b) and 5(c), the base end of the evaluation plate is used as a fulcrum to swing the tip downward, and the surface of the OPP film of the evaluation plate after swinging and the reference surface are aligned. The evaluation plate is tilted downward so that the angle θ formed by , that is, the sliding angle (°) (θ shown in FIG. 5) gradually increases. At this time, the downward tilting speed of the evaluation plate is adjusted so that the sliding angle is 10°/min.
Then, when the droplet started to slide down, the evaluation plate was stopped from swinging, and the sliding angle was measured using a protractor.

Measurement range of sliding angle; 0° to 180°
Measurement atmosphere; ambient temperature 20°C, humidity 30-50%

The properties of the OPP film employed in this experiment are shown below.
Thickness: 41 μm
Contact angle after 60 seconds: 92.3° (front surface), 3.9° (back surface)

When the contact angle was measured as a material evaluation, the OPP film had different contact angles on the front and back of the surface. For this reason, in all experiments using OPP films in this specification, the liquid-contacting surface was unified to the front surface.

The characteristics of the OPP film were measured as follows.

(thickness measurement)
It was measured using a digital micrometer (manufactured by TECLOCK CORPORATION, model number: J Type PG-02).
(contact angle measurement)
A contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number: DROPMASTER DMs400) equipped with a microsyringe (manufactured by Kyowa Interface Science Co., Ltd., model number: product NO584, syringe inner diameter: 0.4 mm) containing pure water (20 ° C.) was used. was measured using The contact angle calculation process was performed according to the manual of the apparatus.

(Evaluation of wettability)
Wettability was evaluated by the following method.
Evaluation of the wettability of the application liquid was evaluated based on the droplet size.
An outline is shown in FIG.
First, using the same stand and clamp as above, a micropipette (manufactured by NICHIRYO, model number: 00-NPX2-1000, inner diameter of pipette tip mouthpiece 4 mm) was fixed to the clamp.
The micropipette is attached to a pipette tip (manufactured by VIOLAMO, model number: 3-6629-13) prepared so that the end face of the connecting port of the micropipette comes to a position 15 mm inward from the end face of the mouthpiece. At this time, the pipette tip is attached to the micropipette so that the end face of the connection port of the micropipette and the end face of the mouthpiece of the pipette tip are parallel to each other.
An OPP film (manufactured by Nippon Paper Industries, model number: #40 30*45) measuring 5 cm square is placed below the micropipette fixed to the stunt, that is, on the vertical line.
Adjust the distance from the tip of the pipette tip of the micropipette to the OPP film to be 30 cm.

In this evaluation method, 0.10 g ± 10% of the applied liquid is weighed with a micropipette, and when it is dropped on the OPP film, the spread of the droplet (droplet diameter (mm)) is measured (memory interval 1.0 mm). measured and evaluated.
When the shape of the droplet is a perfect circle, the diameter of the droplet is calculated as the diameter. On the other hand, when the shape of the droplet is elliptical, the sum of the length a in the major axis direction and the length b in the minor axis direction perpendicular to the major axis direction divided by 2 is taken as the measured value (Fig. 6(b)).

Note that although the droplets dropped during the evaluation may be elliptical, only droplets with a difference between the maximum diameter and the minimum diameter of 2 mm or less were measured.
In addition, if the droplet diameter is high viscosity, the correct amount cannot be aspirated with the micropipette, or if it remains in the pipette tip and the correct amount cannot be dropped, "N/A (not applicable)" evaluated.

In addition, "N/A (not applicable)" in this experiment means that it does not meet the measurement standards and lacks accuracy when expressed as a numerical value.

(Sprayability test)
In the sprayability test, 20 mL of the prepared application liquid is placed in a spray bottle (manufactured by Brothers Co., Ltd., model number: YE10089, capacity 30 mL, type that becomes misty when using pure water), and it is sprayed to evaluate whether it becomes misty. did. If the spray was misty, it was evaluated as ◯, and if it was sprayed differently from when pure water was used, it was evaluated as x.

(Results of Experiment 2)
Experimental results are shown in FIGS. 7 to 25. FIG.

(Relationship between amount of anionic functional groups in fine cellulose fibers and imparting viscosity of application liquid)
FIG. 17 is a diagram showing the relationship between the B-type viscosity and the TI value of the application liquid containing fine cellulose fibers (α-1, β-1, γ-1) having a functional group amount of about 0.5 mmol/g. be.
FIG. 18 is a diagram showing the relationship between the B-type viscosity and the TI value of the application liquid containing fine cellulose fibers (α-2, β-2, γ-2) having a functional group amount of about 1.0 mmol/g. be.
FIG. 19 is a diagram showing the relationship between the B-type viscosity and the TI value of the application liquid containing fine cellulose fibers (α-3, β-3, γ-3) having a functional group amount of about 1.5 mmol/g. be.

In the figure, the portion where the B-type viscosity is 1000 mPa·s is indicated by a broken line, and the range of TI values of 4 to 10 is indicated by oblique lines. The graph in (a) of the figure shows the overall image of the graph. The graph in (b) of the figure is an enlarged view of the portion enclosed by the dashed line in the graph in (a).
In the graph, black plots (●, ▲, ■) indicate Example (S), and white plots (○, Δ, □) indicate Comparative Example (C).

From the results of FIGS. 17, 18, and 19, the application liquid containing fine cellulose fibers exhibited a TI value of 4 or more and 10 or less when the B-type viscosity was 1000 mPa·s or more and 50000 mPa·s or less. The TI value was lower than 4 in the viscosity range lower than 1000 mPa·s.

In the present invention, three types of anionic functional groups (sulfo group, carboxy group and phosphate group) were used as fine cellulose fibers used in the application liquid. Moreover, it prepared so that the amount of functional groups may differ.
As a result, when viscosity characteristics were evaluated as application liquids, surprisingly similar results were obtained regardless of the types and amounts of functional groups.
On the other hand, the HPC-containing application liquids (C-42 to 46) (comparative test) shown in FIG. 16 had a B-type viscosity of 200 mPa·s or less and a TI value of about 1.0.

From the above results, not only the viscosity but also the TI value is high, not only when the spreading agent is applied, but also after spraying (for example, after spraying on an object with an angle, the liquid is retained without dripping). This property was evaluated by the sliding angle.

(Relationship between viscosity of applied liquid and sliding angle)
FIG. 20 is a diagram showing the relationship between the B-type viscosity and the sliding angle of an application liquid containing sulfonated fine cellulose fibers.
FIG. 21 is a diagram showing the relationship between the B-type viscosity and the sliding angle of an application liquid containing TEMPO-oxidized fine cellulose fibers.
FIG. 22 is a diagram showing the relationship between the B-type viscosity of the application liquid containing phosphorylated fine cellulose fibers and the sliding angle.

In the figure, a dashed line indicates the point where the B-type viscosity is 1000 mPa·s. The graph in (a) of the figure shows the overall image of the graph. The graph in (b) of the figure is an enlarged view of the portion enclosed by the dashed line in the graph in (a).
In the graph, black plots () indicate Example (S), and white plots (◯) indicate Comparative Example (C).

From the results of FIGS. 20, 21 and 22, the application liquid containing fine cellulose fibers tended to increase the sliding angle when the B-type viscosity was 1000 mPa·s or more.
The dripping property that measures the sliding angle is assumed to be applied to the leaves of plants (0 to 90 degrees), the stems and trunks that support the plant's own weight (about 90 degrees), and the undersides of leaves (90 to 180 degrees). This is an experimental reflection of the current usage situation.
Some plants have surfaces that easily repel water. Therefore, in this experiment, an OPP film showing a water contact angle of 90° or more was used.
From the experimental results, it was confirmed that when the B-type viscosity is 1000 to 10000 mPa·s, the sliding angle is about 20° or more and 180° or less. On the other hand, the sliding angle of the application liquid containing HPC of the comparative example was 10° to 18° (Fig. 16).

Therefore, the application liquid of the present invention can cover a wide range of uses of the spray liquid. Moreover, it is suggested that the application liquid of the present invention is an unprecedented technology.
Therefore, when the application liquid of the present invention is sprayed on crops, the application liquid can be appropriately attached to the leaves of the crops even if the leaves of the crops are slanted. Moreover, the adhered state can be maintained. In addition, since the application liquid of the present invention has a high viscosity, it can be applied appropriately to plants (for example, plants of the Gramineae family) whose leaf surface angle is nearly vertical while suppressing dripping. suggested that it could be done.
In addition, since the application liquid of the present invention can be appropriately adhered to crops and the like, it is possible to efficiently apply a functional composition (for example, an agricultural chemical, a fertilizer plant growth promoter, etc.) to the application liquid to the crops. can.

From the results of the comparative examples, it seems that it is difficult for the conventional spreading agent to retain the spray liquid on the object to be sprayed (for example, crops) when the TI value is low. In other words, when spraying a spray liquid containing a conventional spreading agent on an object to be sprayed, it may be repelled by the surface of the leaves of the crop, or the liquid may drip, causing the surface of the leaves and stems to It cannot be maintained properly for a long period of time. For this reason, it is difficult for the effect of the spray liquid to be exhibited appropriately, so it is necessary to spray the spray liquid periodically at short intervals. In addition, when the target of spraying is crops, the spray solution often contains an agricultural chemical as a functional composition. Some agricultural chemicals have low safety to humans and the environment.
On the other hand, if the solvent containing fine cellulose fibers of the present invention is used in the same manner as a conventional spreading agent, agricultural chemicals can adhere to the surface of crops for a longer period of time than the spray liquid containing the conventional spreading agent. can be kept Therefore, compared with conventional spray solutions, the amount of agricultural chemicals used can be reduced, which is economical. Moreover, since the amount of environmentally hazardous substances such as pesticides used can be reduced, environmental pollution via soil and water quality can be reduced.

(Effect of addition of surfactant to applied liquid)
Figure 23 shows the effect on viscosity of adding a surfactant to an application liquid containing sulfonated fine cellulose fibers.
In FIG. 23, the graph of (a) is the application liquid using sample α-1 (see FIG. 7), the graph of (b) is the application liquid using sample α-2 (see FIG. 8), and (c) The graph showed the results of the application liquid (see Figure 9) using sample α-3. The graph in (a) of FIG. 23 corresponds to S-4, S-5, S-6, S-7 and S-8 in FIG. 7 in order from the bottom. The graph in (b) of FIG. 23 corresponds to S-12, S-13, S-14, S-15 and S-16 in FIG. 8 in order from the bottom. The graph in (c) of FIG. 23 corresponds to S-20, S-22, S-24, S-26 and S-28 in FIG. 9 in order from the bottom.

Figure 24 shows the effect on viscosity of adding a surfactant to an application liquid containing TEMPO-oxidized microcellulose fibers.
In FIG. 24, the graph of (a) is the application liquid using sample β-1 (see FIG. 10), the graph of (b) is the application liquid using sample β-2 (see FIG. 11), and (c) The graph showed the results of the application liquid using β-3 (see Figure 12). The graph of (a) in FIG. 24 corresponds to S-32, S-33, S-34, S-35 and S-36 in FIG. 10 from the bottom. The graph in FIG. 24(b) corresponds to S-42, S-43, S-44, S-45 and S-46 in FIG. 11 from the bottom. The graph of (c) in FIG. 24 corresponds to S-50, S-51, S-52, S-53 and S-54 in FIG. 12 from the bottom.

FIG. 25 is a diagram showing the effect on viscosity when a surfactant is added to an application liquid containing phosphorylated microcellulose fibers.
In FIG. 25, the graph of (a) is the applied liquid using sample γ-1 (see FIG. 13), the graph of (b) is the applied liquid using sample γ-2 (see FIG. 14), and (c) The graph showed the results of the application liquid (see Figure 15) using sample γ-3. The graph in (a) of FIG. 25 corresponds to S-58, S-59, S-60, S-61 and S-62 in FIG. 13 from the bottom. The graph in FIG. 25(b) corresponds to S-70, S-71, S-72, S-73, and S-74 in FIG. 14 in order from the bottom. The graph of (c) in FIG. 25 corresponds to S-82, S-83, S-84, S-85 and S-86 in FIG. 15 in order from the bottom.

In the figure, the portion where the B-type viscosity is 1000 mPa·s is indicated by a broken line, and the range of TI values of 4 to 10 is indicated by oblique lines.
In the graph, black indicates the B-type viscosity, and white indicates the TI value.
The conditions for each sample in the graph were that the application liquid was prepared so that the cellulose component was 4 parts by mass, the surfactant component was 0 or 5 parts by mass, and the water component was 996 parts by mass (see FIGS. 7 to 15). See Preparation Conditions).

FIG. 23. As shown in FIGS. 24 and 25, the viscosity of the application liquid containing fine cellulose fibers to which a surfactant was added decreased depending on the type of surfactant, but the decrease in viscosity before and after the addition was almost zero. did not occur.
In general, surfactants in spreading agents are often added for the purpose of alleviating the tendency of plants to repel water and increasing the contact area with spray liquids and the like. On the other hand, as shown in FIG. 16, it was confirmed that the liquid containing the conventional surfactant (comparative example) was not viscous. For this reason, it is suggested that conventional spreading agents do not adequately exhibit the effects and efficacy of functional compositions such as agricultural chemicals contained in spray liquids.
On the other hand, since the application liquid containing the fine cellulose fibers of the present invention can be dispersed in water, it is naturally possible to exhibit hydrophilicity. Therefore, by including a surfactant in the application liquid of the present invention, the surface of plants can be coated with the application liquid more than conventional spreading, and thus a further expansion of the range of applications can be expected.

(Experiment 3)
Experiment 3 determined the definition of the atomization state of the sprayability test for the application liquid of the present invention.

(Definition of atomization state by sprayability test)
The atomization state of the sprayability test is classified as "foggy" or "otherwise."
After spraying by the method shown below, the sprayed state is circular with a diameter of 10 cm or more and 15 cm or less (specifically, the shape of the liquid application amount area on the spray plate is circular, and the area area is 78.5 cm). ² or more and 176.6 cm ² or less), it is defined as sprayed “atomized”. In this case, it is written as "○" in the figure.
On the other hand, the sprayed state formed a circular shape with a diameter smaller than 10 cm (specifically, the shape of the liquid application amount region on the spray plate is circular and the region area is smaller than 78.5 cm ² ). defined as sprayed in the “otherwise” condition. In such a spraying state, the spray liquid may drip within 5 minutes after spraying, or the spray may not be sprayed in the first place. In this case, it is written as "x" in the figure.

(Sprayability test)
As a spray container, a spray bottle manufactured by Brothers Co., Ltd. (model number: YE10089, capacity: 30 mL, atomized type when pure water is used) was used.
A clipboard (manufactured by Lion Office Equipment, model number: No. 5) was used as the spray plate. The spray plate was installed vertically. Then, 20 g of the test liquid was placed in a spray bottle, and the tip of the nozzle of the spray bottle was placed so as to face the surface of the spray plate. At this time, the spray bottle was arranged so that the distance from the tip of the nozzle to the surface of the spray plate was 15 cm. Then, the test solution was sprayed five times against the spray plate. After the spraying, the liquid was allowed to stand for 5 minutes, and the presence or absence of dripping was confirmed.
In the experiment, sample α-1, sample δ and pure water were used as test liquids.

(Experimental result)
Sample α-1 could be sprayed "foggy" (forming circles with a diameter of 11.5 cm after spraying). No dripping was observed when the liquid was sprayed and allowed to stand for 5 minutes. On the other hand, sample δ was in an “other” spray state (diameter 5.5 cm), and dripping was observed when the spray was left standing for 5 minutes. In the case of pure water, it could be sprayed in a "mist form" (forming a circle with a diameter of 14.5 cm) as in the sample α-1. However, liquid dripping was confirmed by observation when sprayed and allowed to stand for 5 minutes.

From the above results, when the application liquid of the present invention is sprayed onto an object using a sprayer or the like, even if it has a high viscosity in the static state accommodated in the bottle, during use (when using the spray) ) can be used in the same way as water without problems such as clogging in the liquid feed tube of the spray container or clogging at the tip of the nozzle. For this reason, it was confirmed that the application liquid could be sprayed in a "mist form" onto the target object. Moreover, by adjusting the size of the pores of the nozzle of the spray container, the size of the droplets of the application liquid can be appropriately adjusted, so that the "fog-like" particle size of the application liquid can be adjusted according to the target object. was suggested to be adjustable.

The fine cellulose fiber-containing solvent of the present invention is suitable as a solvent that exhibits wettability and viscosity with respect to liquids. In addition, the application liquid and the application liquid preparation method of the present invention are suitable for applying a liquid to an object.

Claims

A solvent used to improve the wettability of a liquid containing a functional composition and to suppress dripping,
Contains anionic fine cellulose fibers having an average fiber width of 1 nm to 1000 nm in which a part of the hydroxyl groups are substituted with an anionic functional group,
The anionic fine cellulose fibers are
B-type viscosity measured using a B-type viscometer in a state dispersed in pure water so that the solid content concentration is 0.2% by mass or more and 1.0% by mass or less (20 ° C., rotation speed 6 rpm, 3 minutes ) is 1000 mPa·s or more and 50000 mPa·s or less.
2. The fine cellulose fiber-containing solvent according to claim 1, wherein the amount of the anionic functional group introduced is 0.1 mmol/g or more and 3.0 mmol/g or less.
3. The fine cellulose fibers according to claim 1, wherein the anionic functional group is at least one selected from a sulfo group, a phosphate group, a phosphite group, a carboxy group, and a carboxymethyl group. Containing solvent.
Thixotropy measured using a B-type viscometer obtained from the following formula in a state dispersed in pure water so that the solid content concentration of the anionic fine cellulose fibers is 0.2% by mass or more and 1.0% by mass or less 4. The solvent containing fine cellulose fibers according to claim 1, 2 or 3, which has a sex index of 4.0 or more.

Thixotropic index = (viscosity at 20°C and 60 rpm)/(viscosity at 20°C and 60 rpm)
5. The solvent containing fine cellulose fibers according to claim 1, 2, 3 or 4, further comprising a surfactant.
B-type viscometer in a state in which the surfactant is 0.5% by mass and the anionic fine cellulose fibers are dispersed in pure water so that the solid content concentration is 0.2% by mass or more and 1.0% by mass or less. 6. The fine cellulose fiber-containing solvent according to claim 5, wherein the B-type viscosity (20° C., rotation speed 6 rpm, 3 minutes) measured using the above is 1000 mPa·s or more and 20000 mPa·s or less.
Calculated from the following formula in a state in which the surfactant is 0.5% by mass and the anionic fine cellulose fiber is dispersed in pure water so that the solid content concentration is 0.2% by mass or more and 1.0% by mass or less. 7. The solvent containing fine cellulose fibers according to claim 5 or 6, having a thixotropic index of 4.0 or more and 8.0 or less as measured using a Brookfield viscometer.

Thixotropic index = (viscosity at 20°C and 60 rpm)/(viscosity at 20°C and 60 rpm)
A liquid containing water, a functional composition, and a solvent used to improve wettability and suppress dripping,
A liquid for application, wherein the solvent is the solvent containing fine cellulose fibers according to any one of claims 1 to 7.
9. The application liquid according to claim 8, wherein the functional composition is an agricultural chemical, fertilizer, fungicide, disinfectant, soil conditioner, or plant growth promoter.
A method for preparing a liquid containing water, a functional composition, and a solvent used for improving wettability and suppressing dripping,
the solvent is
Contains anionic fine cellulose fibers having an average fiber width of 1 nm to 1000 nm in which a part of the hydroxyl groups are substituted with an anionic functional group,
A method for preparing a liquid to be applied, characterized in that the solid content concentration of the anionic fine cellulose fibers is adjusted to 0.2% by mass or more and 1.0% by mass or less.
11. The method for preparing a liquid for application according to claim 10, wherein the amount of the anionic functional group introduced is 0.1 mmol/g or more and 3.0 mmol/g or less.
12. The application liquid preparation according to claim 10 or 11, wherein the anionic functional group is at least one selected from a sulfo group, a phosphate group, a phosphite group, a carboxy group, and a carboxymethyl group. Method.
13. The method for preparing an application liquid according to claim 10, 11 or 12, characterized by mixing a surfactant.
When adding the solvent, the B-type viscosity measured using a B-type viscometer (20 ° C., rotation speed 6 rpm, 3 minutes) is adjusted to be 1000 mPa s or more and 50000 mPa s or less. 14. The method of preparing an application liquid according to claim 10, 11, 12 or 13.
10, 11, 12, and 13, wherein the solvent is adjusted so that the thixotropic index measured using a Brookfield viscometer obtained from the following formula is 4.0 or more when adding the solvent. Or the application liquid preparation method according to 14.

Thixotropic index = (viscosity at 20°C and 60 rpm)/(viscosity at 20°C and 60 rpm)
16. Application according to claim 10, 11, 12, 13, 14 or 15, characterized in that said functional composition is an agricultural chemical, fertilizer, fungicide, disinfectant, soil conditioner, or plant growth promoter. Liquid preparation method.