WO2023132012A1

WO2023132012A1 - Composition containing fine cellulose fibers, coating material, and thickener

Info

Publication number: WO2023132012A1
Application number: PCT/JP2022/000113
Authority: WO
Inventors: 祥日浅; 朱十西村; 通誉杉野; 聖示西山
Original assignee: 丸住製紙株式会社
Priority date: 2022-01-05
Filing date: 2022-01-05
Publication date: 2023-07-13

Abstract

[Problem] To provide a composition containing fine cellulose fibers in which the CNFs can have improved dispersibility and handleability and a coating material and a thickener which each include the composition containing fine cellulose fibers. [Solution] This composition comprises water, a water-soluble solvent, and sulfonated fine cellulose fibers which are dispersed in a mixture solution composed of the water-soluble solvent and the water and in which some of hydroxyl groups have been replaced with sulfo groups so as to result in an amount of introduced sulfo groups of 0.4-3.0 mmol/g. This composition has a haze of 30% or less when containing the sulfonated fine cellulose fibers in a solid concentration of 0.5 mass%. By using the composition containing fine cellulose fibers for a liquid of interest which has an affinity for the water-soluble solvent, the fine cellulose fibers can be adequately dispersed in the liquid and excellent properties can hence be imparted to the liquid.

Description

Compositions containing fine cellulose fibers, paints and thickeners

The present invention relates to fine cellulose fiber-containing compositions, paints and thickeners. More particularly, it relates to compositions containing fine cellulose fibers for use in target liquids, and paints and thickeners containing the compositions containing fine cellulose fibers.

Cellulose nanofibers (CNF) are microfibers with a fiber width of several to several tens of nanometers and a fiber length of several hundred nanometers, made by nano-processing plant-derived cellulose (mechanical fibrillation, TEMPO catalytic oxidation, etc.). Since CNF has light weight, high elasticity, high strength, and low linear thermal expansion, the use of CNF-containing composite materials is expected in various fields. In particular, it is expected to exert excellent thickening action (high viscosity and thixotropic properties), so development as a novel thickener with less environmental load is underway. For example, in the field of paints, the inclusion of CNF as a thickener is expected to improve coatability and strength of the coating film after drying. On the other hand, it is known that CNF agglomerates and forms so-called lumps in organic solvents such as alcohol, which are generally used as components of water-soluble paints. Therefore, in this field, various developments are underway to solve the above problems (for example, Patent Documents 1 to 3).

Patent Document 1 discloses a composition comprising a fibrous cellulose-containing composition, a resin, and an isocyanate curing agent, wherein the fibrous cellulose-containing composition contains fine particles having a phosphite group or a substituent derived from a phosphite group. A paint containing fibers, a water-soluble low-molecular-weight compound such as urea, and a predetermined saccharide is disclosed. Patent Document 2 discloses a water-based paint containing CNF in a predetermined metal salt, silicate, resin, and water-based solvent. Further, Patent Document 3 discloses a thickener composition for paints or pharmaceuticals containing a predetermined polymer compound, water and CNF having a substituent derived from a carboxyl group.

Japanese Patent No. 6680371 Japanese Unexamined Patent Application Publication No. 2017-110130 JP 2014-141675 A

However, in the paints and thickeners of Patent Documents 1 to 3, although CNF can be dispersed in paints, pharmaceuticals, etc. to some extent, the dispersibility of CNF is insufficient and some CNF precipitates as aggregates. There are problems such as
In addition, the techniques of these documents contain predetermined polymers, sugars, metal salts, etc. in order to disperse CNF in paints, pharmaceuticals, etc., so there are problems such as limited target paints and pharmaceuticals. There is room for improvement from the viewpoint of handleability.

In view of the above circumstances, an object of the present invention is to provide a fine cellulose fiber-containing composition capable of improving the dispersibility and handleability of CNF, and a paint and a thickener containing such a fine cellulose fiber-containing composition. do.

The present inventors have made intensive studies to solve the above problems, and found that the above problems can be solved by using fine cellulose fibers obtained by introducing sulfo groups in a water-soluble solvent. Completed.

The fine cellulose fiber-containing composition of the present invention has a sulfo group introduction amount of 0.4 mmol/g to 3.0 mmol/g, and a sulfone having a haze value of 30% or less at a solid content concentration of 0.5% by mass. It is a mixture of denatured fine cellulose fibers, water, and a water-soluble solvent.
The paint of the present invention is a paint containing the fine cellulose fiber-containing composition of the present invention, and the content of sulfonated fine cellulose fibers in the fine cellulose fiber-containing composition is 0.05% by mass to 10% by mass. is.
The thickener of the present invention is a thickener containing the fine cellulose fiber-containing composition of the present invention, and the content of the sulfonated fine cellulose fibers is 0.1 mass based on the total amount of the thickener. % to 95% by mass.

According to the fine cellulose fiber-containing composition of the present invention, by containing fine cellulose fibers exhibiting predetermined physical property values and having an amount of sulfo groups adjusted within a predetermined range, in a solution containing a water-soluble solvent can maintain the fine cellulose fibers in a dispersed state. Then, if the fine cellulose fiber-containing composition of the present invention is used for a target liquid having affinity for a water-soluble solvent, the fine cellulose fibers can be appropriately dispersed in the target liquid. Excellent properties can be imparted.
According to the paint of the present invention, since the fine cellulose fibers are appropriately dispersed in the paint, the coatability and the stability of the coating film can be improved.
According to the thickener of the present invention, since fine cellulose fibers are appropriately dispersed in the thickener, it is possible to improve thickening properties and thixotropic properties. Therefore, if a thickening agent is used for the target liquid, appropriate thickening properties and thixotropic properties can be imparted.

FIG. 4 is a diagram showing experimental results, and a table showing characteristics (physical properties) of a slurry containing sulfonated cellulose fine fibers (corresponding to the composition containing fine cellulose fibers of the present embodiment). FIG. 4 is a diagram showing experimental results, and a table showing properties (physical properties) of slurry containing sulfonated fine cellulose fibers. FIG. 3 is a diagram showing experimental results, and a table showing properties (physical properties) of a paint containing a slurry containing sulfonated fine cellulose fibers (corresponding to the paint of the present embodiment). FIG. 3 is a diagram showing experimental results, and a table showing properties (physical properties) of a paint containing a slurry containing sulfonated fine cellulose fibers (corresponding to the paint of the present embodiment). FIG. 3 is a diagram showing experimental results, and a table showing properties (physical properties) of a paint containing a slurry containing sulfonated fine cellulose fibers (corresponding to the paint of the present embodiment). FIG. 3 is a diagram showing experimental results, and a table showing characteristics (physical properties) of cosmetics containing a slurry containing sulfonated fine cellulose fibers (corresponding to the cosmetics of the present embodiment).

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described based on the drawings.
The fine cellulose fiber-containing composition of the present embodiment is characterized by being able to impart excellent properties to the target liquid by containing the sulfonated fine cellulose fibers having affinity with the water-soluble solvent. are doing.

<Composition containing fine cellulose fibers of the present embodiment>
The fine cellulose fiber-containing composition of the present embodiment is a composition containing water, a water-soluble solvent, and sulfonated fine cellulose fibers.

(Water-soluble solvent for fine cellulose fiber-containing composition of the present embodiment)
First, the water-soluble solvent contained in the composition containing fine cellulose fibers of the present embodiment will be described.
The water-soluble solvent of the fine cellulose fiber-containing composition of the present embodiment is not particularly limited as long as it is a solvent that is miscible with water.
Specifically, in addition to water-soluble organic solvents that are generally used in chemical experiments, water-soluble solvents that are industrially used can be used. For example, those having a solubility in water (g/100 mL water) of 10 g or more are suitable as water-soluble solvents.

Examples of water-soluble solvents include lower alcohols such as methanol, ethanol, propanol, isopropyl alcohol, and butanol, ethylene glycol, acetic acid, tetrahydrofuran, dioxane, acetone, ethyl methyl ketone, acetonitrile, pyridine, dimethyl sulfoxide, and derivatives thereof. etc., and these substances can be used alone or in combination of two or more.
The water-soluble solvent is not limited to these substances as long as it has the functions described above.

For example, if the target liquid is cosmetics that are used on humans, ethanol, isopropyl alcohol, etc., which have little effect on humans, can be used as water-soluble solvents. Further, when the target liquid is a paint or the like, a highly volatile solvent such as methanol or propylene glycol monomethyl ether 1-methoxy-2-propanol (PM) can be used as the water-soluble solvent.

(Target liquid of the fine cellulose fiber-containing composition of the present embodiment)
The target liquid in which the composition containing fine cellulose fibers of the present embodiment can be used (liquid to which the composition containing fine cellulose fibers of the present embodiment is added or mixed) has affinity with a water-soluble solvent. There is no particular limitation as long as it is a liquid.
For example, not only complete liquids such as water, but also water-based or oil-based paints containing insoluble substances such as pigments, liquid cosmetics such as lotions and liquid medicines, as well as gels such as cleansing agents and moisturizing creams. Various liquids such as external skin preparations of various properties such as cosmetics in the form of liquids and slurries can be mentioned as target liquids, but it is needless to say that the liquids are not limited to these.

(Water of the fine cellulose fiber-containing composition of the present embodiment)
Water contained in the fine cellulose fiber-containing composition of the present embodiment is not particularly limited. For example, in addition to general tap water, pure water, distilled water, ion-exchanged water, RO water, Milli-Q water, ultrapure water, and the like can be used.

(Sulfonated fine cellulose fibers of fine cellulose fiber-containing composition of the present embodiment)
The sulfonated fine cellulose fibers contained in the fine cellulose fiber-containing composition of the present embodiment are fine cellulose fibers obtained by refining cellulose fibers.
The sulfonated fine cellulose fibers contain a plurality of finer cellulose fibers (hereinafter referred to as unit fibers).

Specifically, sulfonated fine cellulose fibers are fibers formed by connecting multiple unit fibers. In this unit fiber, at least part of the hydroxyl group (--OH group) of cellulose (chain polymer in which D-glucose is β(1→4) glycoside-bonded, general formula (1)) constituting such fiber is It is sulfated with a sulfo group represented by the general formula (2). In other words, the sulfonated fine cellulose fibers are obtained by substituting some of the hydroxyl groups of the fine cellulose fibers with sulfo groups.

(general formula (1))

(general formula (2))

The term "substitution" as used herein refers to the replacement of hydroxyl groups of cellulose with sulfo groups, and means that at least some of the hydroxyl groups constituting the cellulose after the reaction are bonded with sulfo groups through a substitution reaction or the like.
Specifically, in this specification, the hydroxyl groups of cellulose are substituted with sulfo groups, meaning that at least part of the hydroxyl groups (--OH groups) of cellulose are substituted with sulfo groups. A part of the hydroxyl group means to include not only the "H" (hydrogen atom) of the "--OH group" but also the "OH".
That is, in a structure in which a portion of the hydroxyl groups of cellulose is substituted with a sulfo group, the sulfo group is bonded to the oxygen atom of the hydroxyl group instead of the hydrogen atom (H), and the carbon of the cellulose and the oxygen atom of the hydroxyl group (O ) and a sulfo group (so-called ester bond, for example, general formula (3)).
In addition, the structure in which a portion of the hydroxyl groups of cellulose is substituted with a sulfo group includes a structure in which a sulfo group is directly bonded to the carbon to which the hydroxyl group of cellulose is bonded (e.g., general formula (4)). .

(general formula (3))

(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 (3) 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 (4))

The sulfo group in general formula (4) can also be represented in the same manner as in general formula (3), and Z can also include similar compounds.

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. may contain.
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 can be represented by the amount of sulfur derived from the sulfo groups, and the amount of sulfo groups introduced is not particularly limited.
For example, the amount of sulfo groups introduced per 1 g (mass) of sulfonated fine cellulose fibers is preferably adjusted to be higher than 0.4 mmol/g, more preferably 0.4 mmol/g to 9.9 mmol. /g, more preferably 0.5 mmol/g to 9.9 mmol/g, even more preferably 0.6 mmol/g to 9.9 mmol/g.

When the amount of sulfo groups introduced per 1 g (mass) of sulfonated fine cellulose fibers is 0.4 mmol/g or less, hydrogen bonding between fibers is strong, and dispersibility tends to decrease. Conversely, when the amount of the sulfo group introduced is higher than 0.4 mmol/g, the dispersibility tends to be improved, and when the amount is 0.5 mmol/g or more, the electronic repulsion can be strengthened. , it becomes easier to maintain the dispersed state more stably.
In other words, in order to homogenize the viscosity of the dispersion liquid in which the sulfonated fine cellulose fibers described later are dispersed at a predetermined concentration, the amount of sulfo groups introduced is preferably higher than 0.4 mmol/g, more preferably 0. .5 mmol/g or more is preferable. On the other hand, as the amount of sulfur introduced approaches 9.9 mmol/g, there is concern that the crystallinity will decrease, and the cost of introducing sulfur tends to increase.
Therefore, the amount of sulfo groups introduced into the sulfonated fine cellulose fibers is preferably adjusted to be higher than 0.4 mmol/g and 3.0 mmol/g or less, more preferably 0.5 mmol/g to 3.0 mmol/g. .0 mmol/g, more preferably 0.5 mmol/g to 2.0 mmol/g, even more preferably 0.5 mmol/g to 1.7 mmol/g, more preferably 0.5 mmol/g ~1.5 mmol/g.
Also from the viewpoint of the transparency of the sulfonated fine cellulose fibers, it is preferable to adjust the amount of the sulfo group to be introduced so as to fall within the same range as the above range.

The sulfonated fine cellulose fibers preferably have the transparent structure described above.
Specifically, it is a sulfonated fine cellulose fiber having a structure prepared so that the haze value of a dispersion liquid in which the sulfonated fine cellulose fiber has a solid content concentration of 0.5% by mass is 30% or less. The structure of the sulfonated fine cellulose fibers preferably has a haze value of 20% or less, more preferably has a haze value of 15% or less, and still more preferably has a haze value of 10% or less. Those having a structure are preferred.

As described above, since the composition containing fine cellulose fibers of the present embodiment contains sulfonated fine cellulose fibers having a predetermined structure, the fine cellulose fibers can be maintained in a dispersed state in the presence of a water-soluble solvent. can. In other words, the composition containing fine cellulose fibers of the present embodiment is a composition having a predetermined transparency, and such transparency is due to the sulfonated fine cellulose fibers having the structure described above. The coexistence of the sulfonated fine cellulose fibers having such a structure with the water-soluble solvent suppresses the formation of aggregates (lumps).
Therefore, if the composition containing fine cellulose fibers of the present embodiment is added to a target liquid (liquid having affinity for a water-soluble solvent), the target liquid can The sulfonated fine cellulose fibers can be easily dispersed therein.
As a result, the effects of the sulfonated fine cellulose fibers on the target liquid, such as improved viscosity and desired thixotropy, can be exhibited. In other words, if the composition containing fine cellulose fibers of the present embodiment is used in a target liquid, it is possible to impart excellent properties resulting from the sulfonated fine cellulose fibers to the target liquid.

Although the reason why the water-soluble solvent in the composition containing fine cellulose fibers of the present embodiment affects the dispersibility of the sulfonated fine cellulose fibers is not clear, the following reasons are presumed.

In the composition containing fine cellulose fibers of the present embodiment, the sulfo groups possessed by the sulfonated fine cellulose fibers and the hydrophilic groups of the water-soluble solvent interact with each other through, for example, hydrogen bonding, whereby the sulfonated fine cellulose fibers are separated from each other. It is estimated that the aggregation of is suppressed.
As will be described later, when the fine cellulose fiber-containing composition of the present embodiment is added to or mixed with a target liquid and used, the water-soluble solvent is mixed with the component in the target liquid with affinity in the target liquid. It is presumed that the aggregation of the sulfonated fine cellulose fibers is suppressed by the combination, and the sulfonated fine cellulose fibers are easily dispersed in the target liquid. In other words, if the water-soluble solvent of the fine cellulose fiber-containing composition of the present embodiment has the property of being easily mixed with the components in the target liquid, or has affinity, the sulfonated fine It is thought that the cellulose fibers can be dispersed more appropriately.

(Method for evaluating amount of introduced sulfo group)
The amount of sulfo groups introduced into the sulfonated fine cellulose fibers may be evaluated by directly measuring the sulfo groups, or may 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.
As the latter measurement method, for example, a predetermined amount of sulfonated fine cellulose fibers is combusted, and the sulfur content in the combusted material is measured using a combustion ion chromatograph in accordance with IEC 62321. It can be calculated based on the value.

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 0.4 mmol/g, the amount of sulfo groups introduced is naturally 0.4 mmol/g.

The former measuring method (method using electrical conductivity) will be described more specifically.
First, 1/10 by volume of a slurry containing 0.2% by mass of nanocellulose fibers is added with a strongly acidic ion exchange resin (Amberjet 1024; conditioned by Organo Co., Ltd.) and shaken for 1 hour or more. (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.

In the case of preparing sulfonated fine cellulose fibers by refining chemically treated sulfonated pulp as described later, the amount of sulfur introduced into the sulfonated pulp before refining may be used.

(Average fiber width of sulfonated fine cellulose fibers)
The structure of the sulfonated fine cellulose fibers is described in detail below.
The sulfonated fine cellulose fibers are fine cellulose fibers obtained by making cellulose fibers fine as described above, and the fibers are prepared to have a very fine structure. Such a structure improves dispersibility in a water-soluble solvent and enables proper dispersion in a solution. In other words, by evaluating the transparency, it is possible to identify the sulfonated fine cellulose fibers contained in the fine cellulose fiber-containing composition of the present embodiment. The sulfonated fine cellulose fibers having such a structure are maintained in a dispersed state in the presence of a water-soluble solvent in the fine cellulose fiber-containing composition of the present embodiment.
For example, the sulfonated fine cellulose fibers of the fine cellulose fiber-containing composition of the present embodiment are preferably prepared so that the average fiber width is 1 nm to 30 nm when observed with an electron microscope, and more preferably. is prepared to be 2 nm to 30 nm.
When the average fiber width of the sulfonated fine cellulose fibers exceeds 30 nm, the aspect ratio tends to decrease. There is a possibility that it may become difficult to exert an appropriate effect (for example, viscosity, etc.) when it is added.

Therefore, the average fiber width of the sulfonated fine cellulose fibers is preferably 2 nm to 30 nm, more preferably 2 nm to 20 nm, still more preferably 2 nm to 10 nm, in terms of improving viscosity.

The aspect ratio (average fiber length/average fiber width) of the sulfonated fine cellulose fibers is preferably 20 or more, more preferably 50 or more, and still more preferably 100 or more, depending on the average fiber length described later. be.

In addition, when the average fiber width is larger than 30 nm, it approaches 1/10 of the wavelength of visible light, and when it is combined with a matrix material, refraction and scattering of visible light easily occur at the interface, and scattering of visible light occurs. As a result, transparency, which will be described later, tends to decrease.
For example, in the case of the paint of the present embodiment, which will be described later, if the fiber width is 30 nm or less, the fiber width is 1/10 or less of the wavelength of visible light, and when combined with the paint composition, the light is not scattered and the fiber is transparent. The advantage is that a paint with high toughness can be obtained.
Therefore, from the viewpoint of transparency, which will be described later, the sulfonated fine cellulose fibers are preferably prepared so that the average fiber width is 20 nm or less, more preferably 10 nm or less. . In particular, if the average fiber width is adjusted to 10 nm or less, scattering of visible light can be further reduced, so sulfonated fine cellulose fibers having high transparency can be obtained.

The average fiber width of sulfonated microcellulose 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.

(Transparency of sulfonated fine cellulose fibers)
Since the sulfonated fine cellulose fibers have a structure having the average fiber width described above, they exhibit a certain level of transparency in a slurry state.
For example, sulfonated fine cellulose fibers exhibit a total light transmittance of 90% or more when prepared to have a solid content concentration of 0.5% by mass. This total light transmittance is more preferably 95% or more.
In addition, the sulfonated fine cellulose fibers exhibit a haze value of 30% or less when prepared to have a solid content concentration of 0.5% by mass. This haze value is preferably 20% or less, more preferably 15% or less, and still more preferably 10% or less.
Details of the measurement method will be described later.

(Viscosity and thixotropic index of sulfonated fine cellulose fibers)
The sulfonated fine cellulose fibers have the above-described average fiber width and have an elongated fibrous structure (for example, the aspect ratio is 20 or more), so that they exhibit predetermined viscosity characteristics in a slurry state. .
For example, the sulfonated fine cellulose fiber has a viscosity of 3000 mPa· when measured using a Brookfield viscometer at a solid content concentration of 0.5% by mass at 20 ° C. and a rotation speed of 6 rpm for 3 minutes. s (3 Pa·s) or more.
In addition, the sulfonated fine cellulose fibers were measured using a Brookfield viscometer at a solid content concentration of 0.5% by mass at 20 ° C. and a rotation speed of 6 rpm and a rotation speed of 60 rpm. is calculated, and the thixotropic index calculated from each viscosity ratio (viscosity at 6 rpm/viscosity at 60 rpm) exhibits 5.0 or more.
Details of the measurement method will be described later.

(Water, water-soluble solvent, content of sulfonated fine cellulose fibers)
The content ratio (mixture ratio) of water, water-soluble solvent and sulfonated fine cellulose fibers contained in the composition containing fine cellulose fibers of the present embodiment is not particularly limited, but is prepared so as to have the following ratios. can do.

The content of water can be blended to 20 to 300 parts by mass with respect to 1 part by mass of sulfonated fine cellulose fibers. It is preferably 40 parts by mass or more, more preferably 100 parts by mass or more based on 1 part by mass of the sulfonated fine cellulose fibers.

The content of the water-soluble solvent can be blended so as to be 10 to 300 parts by mass with respect to 100 parts by mass of water. That is, the content of the water-soluble solvent can be blended so as to be 2 to 900 parts by mass with respect to 1 part by mass of the sulfonated fine cellulose fibers.
The content of the water-soluble solvent may be within the above range, preferably 300% by mass or less, more preferably 200% by mass or less, and still more preferably 150% or less with respect to 100 parts by mass of water, Even more preferably, it is 100% by mass. On the other hand, the lower limit is 10% by mass or more, more preferably 20% by mass or more, relative to 100 parts by mass of water.

For example, the mixing ratio of water and water-soluble solvent can be adjusted so that the mass ratio (g of water/g of solvent) is 0.25 to 100. When 20 g of water and 80 g of a water-soluble solvent are mixed, the mixing ratio (mixing ratio) of the two is 0.25 in mass ratio.

The fine cellulose fiber-containing composition of the present embodiment may contain components other than those mentioned above. Optional components include, for example, antifoaming agents, lubricants, ultraviolet absorbers, dyes, pigments, stabilizers, surfactants, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, organic particles, antistatic agents. , magnetic powders, orientation promoters, plasticizers, preservatives, cross-linking agents, and the like. Moreover, you may add an organic ion as an arbitrary component.

The cellulose microfiber-containing composition of this embodiment may combine sulfonated cellulose microfibers with certain ingredients.
For example, both can be provided separately, optionally in combination with other ingredients. In this case, the combined amounts and ratios of the sulfone fine cellulose fibers and specific components may be adjusted so as to be the same as the compounding amounts of the fine cellulose fiber-containing composition.

Further, the form of the fine cellulose fiber-containing composition of the present embodiment is not particularly limited. For example, they can exist in various forms such as slurries and dispersions.

(About transparency)
In the prior art, when fine cellulose fibers are mixed with a water-soluble solvent, it is known that the dispersibility of the fine cellulose fibers is reduced due to the influence of the water-soluble solvent, resulting in the formation of aggregates (lumps) of the fine cellulose fibers. It is
However, in the fine cellulose fiber-containing composition of the present embodiment, by containing the sulfonated fine cellulose fibers having the structure described above, cohesiveness of the sulfonated fine cellulose fibers is suppressed even in the presence of a water-soluble solvent. and excellent dispersibility.
The dispersion state of the sulfone fine cellulose fibers in the fine cellulose fiber-containing composition of the present embodiment can be evaluated by transparency.

The term "transparency" as used herein is a concept that includes both or either of the properties of liquid transparency and turbidity. That is, in the evaluation of transparency in this specification, the haze value can be used to more appropriately evaluate the turbidity of the liquid, and the total light transmittance can be used to more appropriately evaluate the transparency.

(Total light transmittance of fine cellulose fiber-containing composition)
For example, the fine cellulose fiber-containing composition of the present embodiment has a total light transmittance of 90% or more when the sulfonated fine cellulose fibers are prepared to have a solid content concentration of 0.5% by mass. This total light transmittance is more preferably 95% or more.

(Haze value of fine cellulose fiber-containing composition)
Further, as described above, the haze value can evaluate the turbidity of the liquid, and therefore, like the total light transmittance, the dispersibility of the sulfonated fine cellulose fibers in the fine cellulose fiber-containing composition of the present embodiment can be evaluated. can do.
For example, the fine cellulose fiber-containing composition of the present embodiment has a haze value of 30% or less when the sulfonated fine cellulose fibers are prepared to have a solid content concentration of 0.5% by mass. The haze value is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less.

When the composition containing fine cellulose fibers of the present embodiment has a haze value of 30% or less, the sulfonated fine cellulose fibers are maintained in an appropriately dispersed state in the presence of a water-soluble solvent. In the case of a paint containing a fine cellulose fiber-containing composition, handleability is improved. Moreover, since the fine cellulose fiber-containing composition has transparency, the color of the paint can be exhibited appropriately. For example, in the case of paint containing no pigment (transparent paint), the film after coating can exhibit good transparency. In addition, by setting the total light transmittance to 90% or more, there is also the advantage that the effect of a transparent paint when formed into a coating film can be easily exhibited.

As described above, the fact that the fine cellulose fiber-containing composition of the present embodiment has the transparency as described above means that the contained sulfonated fine cellulose fibers have excellent dispersibility. be. The sulfonated fine cellulose fibers having such excellent dispersibility have a structure suitable for dispersibility. That is, the fact that the fine cellulose fiber-containing composition of the present embodiment has the transparency as described above means that the contained sulfonated fine cellulose fibers have the above-described predetermined structure.
If the composition containing fine cellulose fibers of the present embodiment has transparency as described above, the sulfonated fine cellulose fibers have a structure capable of maintaining a dispersed state in the presence of a water-soluble solvent. It's becoming

(Transparency measuring method)
The total light transmittance and haze value can be measured by a method using a spectroscopic haze meter described in Examples below.
For example, the composition containing fine cellulose fibers of the present embodiment in which sulfonated fine cellulose fibers are dispersed at a predetermined concentration is measured using a spectrophotometer in accordance with JIS K 7105 to determine the haze value and total light transmittance. can be asked for.

(viscous and thixotropic index)
The fine cellulose fiber-containing composition of the present embodiment preferably has predetermined viscosity characteristics. Specifically, the fine cellulose fiber-containing composition of the present embodiment is prepared to have a predetermined viscosity and thixotropic index.

As the viscosity, for example, the viscosity measured at 20° C., 6 rpm, and 3 minutes using a Brookfield viscometer in a state where the solid content concentration of the sulfonated fine cellulose fibers is 0.5% by mass. , 3000 mPa·s (3 Pa·s) or more and 40,000 mPa·s (40 Pa·s) or less (see Examples 1 to 5).
The upper limit of the viscosity is preferably 35,000 mPa·s (35 Pa·s) or less, more preferably 10,000 mPa·s (10 Pa·s) or less. On the other hand, the lower limit of the viscosity is preferably higher than 3,000, more preferably 4,000 mPa·s (4 Pa·s) or more, and still more preferably 5,000 mPa·s (5 Pa·s). or more, and more preferably 6,000 mPa·s (6 Pa·s) or more.

The thixotropic index is measured, for example, using a Brookfield viscometer at a solid content concentration of 0.5% by mass of the sulfonated fine cellulose fibers at 20° C. at 6 rpm and 60 rpm. , Each viscosity is calculated, and the thixotropic index calculated from each viscosity ratio (viscosity at a rotation speed of 6 rpm/viscosity at a rotation speed of 60 rpm) is 5.0 or more, preferably 7.0 or more ( See Examples 1-5).

Such viscosity characteristics of the composition containing fine cellulose fibers of the present embodiment are presumed to be due to the fiber structure of the sulfonated fine cellulose fibers contained therein. In other words, it is speculated that the sulfonated fine cellulose fibers having the above-described predetermined structure can exhibit such characteristics in the fine cellulose fiber-containing composition.
Since the fine cellulose fiber-containing composition of the present embodiment exhibits excellent viscosity characteristics as described above, it is possible to impart effects based on such viscosity characteristics to the target liquid.

<Paint of this embodiment>
The paint of this embodiment is a paint containing the composition containing fine cellulose fibers of this embodiment described above.
Since the coating material of the present embodiment contains the composition containing fine cellulose fibers of the present embodiment, the viscosity characteristic of the composition containing fine cellulose fibers of the present embodiment is set to the lower limit value or higher, so that when a coating film is formed, It is possible to optimize the dispersibility of the fibers, Young's modulus and strength. Therefore, coatability and coating performance can be improved. A specific description will be given below.

(Content of fine cellulose fiber-containing composition)
The content ratio (content rate) of the fine cellulose fiber-containing composition of the present embodiment in the paint of the present embodiment is as long as the content of the sulfonated fine cellulose fibers in the paint of the present embodiment is within the range shown below. , is not particularly limited.

For example, the content of the sulfonated fine cellulose fibers in the paint of this embodiment is adjusted to 0.05% by mass to 10% by mass. The content of the sulfonated fine cellulose fibers is adjusted to 0.05% by mass to 10% by mass in the total amount of the paint of this embodiment.
The lower limit of the content of the sulfonated fine cellulose fibers is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0.3% by mass or more. is. On the other hand, the upper limit is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

For example, the paint of the present embodiment can be prepared by mixing the fine cellulose fiber-containing composition of the present embodiment in which the solid content concentration of sulfonated fine cellulose fibers is 1%, and a mixing paint. When 20 g of the former and 80 g of the latter are mixed, the mass ratio (g of fine cellulose fiber-containing composition/g of paint for mixing) is 20 g/80 g (0.25). In this case, the content of sulfonated fine cellulose fibers in the paint of this embodiment is ((20×0.01)/100)×100=0.2% by mass.

(resin)
The paint of the present embodiment may contain a resin such as a thermoplastic resin, a thermosetting resin, or a photocurable resin.
Examples of resins include styrene resins, acrylic resins, aromatic polycarbonate resins, aliphatic polycarbonate resins, aromatic polyester resins, aliphatic polyester resins, aliphatic polyolefin resins, cyclic olefin resins, and polyamides. resin, polyphenylene ether resin, thermoplastic polyimide resin, polyacetal resin, polysulfone resin, amorphous fluorine resin, rosin resin, nitrocellulose, vinyl chloride resin, chlorinated rubber resin, vinyl acetate resin, Examples include, but are not limited to, phenolic resins, epoxy resins, and the like.

The resin content is preferably 30 parts by mass or more, more preferably 70 parts by mass or more, and still more preferably 100 parts by mass or more, relative to 1 part by mass of the sulfonated fine cellulose fibers. The upper limit of the resin content is preferably 500 parts by mass or less, more preferably 300 parts by mass or less, and still more preferably 200 parts by mass or less per 1 part by mass of the sulfonated fine cellulose fibers. By including the resin in such a content as described above, the effect of the specific component can be suitably exhibited, and coatability, smoothness of the coating film, and optimization of elastic modulus and strength can be realized.

(curing agent)
The paint of this embodiment may contain a curing agent.
As the curing agent, a known one can be appropriately used, and examples thereof include isocyanate curing agents (polyisocyanate, etc.), epoxy (oxirane) curing agents, oxetane curing agents, and the like. In the present invention, isocyanate-based curing agents are particularly preferred.

The content of the curing agent is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more with respect to 1 part by mass of the sulfonated fine cellulose fibers. In addition, the upper limit of the content of the curing agent is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 60 parts by mass or less with respect to 1 part by mass of the sulfonated fine cellulose fibers. . By including the curing agent in the above content, the effect of the above specific component can be favorably exhibited, and coatability, smoothness of the coating film, optimization of elastic modulus, and the like can be realized.

The paint of this embodiment may contain components other than the components described above. Other components include, for example, antifoaming agents, lubricants, ultraviolet absorbers, dyes, pigments, stabilizers, surfactants, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, organic particles, antistatic agents. , magnetic powders, orientation promoters, plasticizers, preservatives, cross-linking agents, and the like. Moreover, you may add an organic ion as an arbitrary component.

(viscous and thixotropic index)
The paint of the present embodiment preferably has predetermined viscosity characteristics (viscosity, thixotropy). By exhibiting such viscosity characteristics, handleability can be improved.

As the viscosity, for example, using a Brookfield viscometer in a state where the solid content concentration of the sulfonated fine cellulose fibers is 0.1% by mass to 1.0% by mass, 20 ° C. and rotation speed 6 rpm, 3 minutes Viscosity measured under conditions can be adjusted to 10 mPa·s (0.01 Pa·s) or more (see Examples 8 to 10).
Although the upper limit of the viscosity is not particularly limited, it is preferable to prepare the viscosity so as not to affect the coatability. For example, from the viewpoint of coatability, the upper limit of the viscosity of the paint of the present embodiment is preferably 4,000 mPa s (4 Pa s) or less, more preferably 3,000 mPa s (3 Pa s) or less. , more preferably 2,000 mPa·s (2 Pa·s) or less, and still more preferably 1,000 mPa·s (1 Pa·s) or less.
On the other hand, the lower limit of the viscosity is preferably 10 mPa s (0.01 Pa s) or more, more preferably 100 mPa s (0.1 Pa s) or more, and still more preferably It is 300 mPa·s (0.3 Pa·s) or more, and more preferably 500 mPa·s (0.5 Pa·s) or more.

As the thixotropic index, for example, using a Brookfield viscometer in a state where the solid content concentration of the sulfonated fine cellulose fiber is 0.1% by mass to 1.0% by mass, 20 ° C., 6 rpm and rotation A thixotropic index calculated from each viscosity ratio (viscosity at 6 rpm/viscosity at 60 rpm) is preferably 1.5 or more, preferably 2.0 or more (see Examples 8-10).

(Coating film)
The paint of the present embodiment can form a coating film when applied. For example, a coating film can be formed by a step of applying the coating material of the present embodiment onto a substrate and a step of drying it. The formed coating film may be peeled off from the base material and used in the form of a sheet. Moreover, you may form into a sheet form by paper-making the coating material of this embodiment.

The thickness of the coating film thus formed is not particularly limited, but when considering the form of use as a paint, it is preferably 1000 μm or less, more preferably 500 μm or less, and 300 μm or less. is more preferable, 100 μm or less is more preferable, and 80 μm or less is particularly preferable. The lower limit is preferably 1 µm or more, more preferably 5 µm or more, and particularly preferably 10 µm or more.

The transparency of the coating film is not particularly limited.
For example, it preferably has a high total light transmittance or a low haze value. For example, the total light transmittance is preferably 80% or more. In addition, since the total light transmittance (%) of a methacrylic film having high transparency is about 90%, it is more preferably 90% or more, and 95% or more when exhibiting the same transparency. It is even more preferable to have
The haze value is preferably 30% or less, for example. In addition, since the haze value (%) of a film made of polyethylene, which is a general-purpose resin, is about 20%, it is more preferably 20% or less, more preferably 10% or less, when exhibiting the same transparency. % or less is particularly preferred.

In the case where the paint of the present embodiment contains a resin that exhibits opacity, the transparency of the film after drying is such that the total light transmittance of the coated film after coating is 90% or more, and the haze value is 30% or less is sufficient.

The Young's modulus of the coating film is not particularly limited, but when considering a higher Young's modulus, for example, it is preferably 0.3 GPa or more, more preferably 0.5 GPa or more, and 0.7 GPa or more. is more preferable, and 0.8 GPa or more is particularly preferable. It is practical that the upper limit is 8 GPa or less. Since the present invention can achieve such a high Young's modulus, it can be suitably applied to applications requiring a high elastic modulus.

The Young's modulus of the coating film was measured using a tensile tester Tensilon (manufactured by A&D Co., Ltd.) according to JIS P 8113:2006 except that the test piece length between the grips was 50 mm and the tensile speed was 5 mm / min. Measure in compliance.
When measuring the Young's modulus, a test piece conditioned at 23° C. and a relative humidity of 50% for 24 hours is used. The measurement is performed 5 times per level, and the average value is adopted.

The quick-drying property of the coating film is not particularly limited.
For example, from the viewpoint of workability, it is preferable that the quick-drying property is high. For example, when dried using a dryer set at 50 ° C., the mass due to volatilization of the solvent after 10 minutes is preferably 70% or less of the mass before drying, more preferably 60% or less, 50 % or less is more preferable.

<Thickening agent of the present embodiment>
The thickener of the present embodiment is a thickener containing the fine cellulose fiber-containing composition of the present embodiment described above. The thickener of this embodiment can be used for various purposes. For example, it can be used by mixing with skin medicinal agents such as cosmetic agents and moisturizing cream agents.
Since the thickener of the present embodiment contains the fine cellulose fiber-containing composition of the present embodiment, by setting the viscosity characteristics of the fine cellulose fiber-containing composition of the present embodiment to the lower limit or more, the applicability is improved. can be improved. A specific description will be given below.

The content ratio of the fine cellulose fiber-containing composition of the present embodiment is not particularly limited. For example, the content of the sulfonated fine cellulose fibers is adjusted to 0.1% by mass or more based on the total amount (the total amount of the thickener). More specifically, it is 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more with respect to the total amount (total amount of the thickener). is. This content may be 30% by mass or more, 40% by mass or more, 50% by mass or more, 55% by mass or more, or 90% by mass or 95% by mass. From the viewpoint of handleability, the content of the fine cellulose fiber-containing composition of the present embodiment is preferably 90% by mass or less.
In particular, the thickener of the present embodiment is preferably prepared so that the amount of the fine cellulose fiber-containing composition of the present embodiment contained is 80% by mass or more with respect to the total amount of the thickener. It is more preferably 90% by mass or more, and still more preferably 95% by mass or more.

The thickener of the present embodiment preferably exhibits the thixotropic index described above as the viscosity characteristic of the composition containing fine cellulose fibers of the present embodiment.
When the thickener of the present embodiment is used by mixing or adding it to a skin medicinal agent such as a cosmetic agent or a moisturizing cream agent, the viscosity is reduced due to shear stress caused by stirring during use, and the viscosity is reduced. It is advantageous in that the viscosity can be recovered after application and the fixability can be improved. The ease of application and recovery of viscosity after application are collectively referred to as application properties.

In addition, many sunscreen cosmetics generally contain metals such as titanium oxide and zinc oxide, and derivatives thereof, as UV scattering agents. In such a sunscreen cosmetic, a substance such as titanium oxide settles and separates when left standing. For this reason, it is necessary to shake firmly before use to disperse the anti-ultraviolet material such as titanium oxide. In addition, when the action of shaking is insufficient, the sunscreen function may not be exhibited appropriately. Similarly, other cosmetics that require sebum adsorption such as mica, zinc oxide, talc, hydroxyapatite, aluminum silicate, etc., described in the examples described later, are sebum-adsorbing materials that settle and need to be shaken firmly when used. Examples include lotions and milky lotions containing ingredients.
On the other hand, if the thickener of the present embodiment is used by adding it to the cosmetics as described above, it is possible to suppress the sedimentation of the useful ingredients as described above in a still state. In other words, the uniformly dispersed state of the UV inhibitor can be maintained without performing an action such as shaking to uniformly disperse the UV inhibitor during use. For this reason, even if it is used as it is in a stationary state, it is possible to obtain the advantage that the skin protection performance from ultraviolet rays and the like can be appropriately exhibited.
In other words, if the thickener of the present embodiment is mixed or added and used, it can function as a dispersion stabilizer for other useful ingredients.

<Method for producing sulfonated fine cellulose fibers>
The method for producing the sulfonated fine cellulose fibers contained in the fine cellulose fiber-containing composition of the present embodiment involves finely treating sulfonated pulp produced by the following production method (sulfonated pulp production method). However, it is not limited to such a manufacturing method.

The outline of this sulfonated pulp manufacturing method is that the sulfonated pulp contained in the redispersible pulp of the present embodiment (hereinafter simply referred to as sulfonated pulp) is obtained by subjecting a fibrous raw material containing cellulose (for example, wood pulp) to a chemical treatment process. ) is a method of manufacturing.

This chemical treatment step is a method of bringing the supplied fiber raw material into contact with a reaction solution (contact step) and then subjecting it to a heating reaction (reaction step) to sulfonate the hydroxyl groups of cellulose.
As used herein, the fiber raw material refers to a fibrous pulp or the like containing cellulose molecules. Pulp is a fibrous member in which a plurality of cellulose fibers are aggregated. The cellulose fibers are aggregates of a plurality of fine fibers (for example, microfibrils). The 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 aggregate of cellulose fibers having a size of 200 mesh or 235 mesh that can be a residue. Details of the fiber raw material will be described later.

As described above, the chemical treatment step includes a contact step of contacting cellulose fibers of a fiber raw material containing cellulose such as pulp with sulfamic acid, which is a sulfonating agent having a sulfo group, and urea, and the pulp after this contact step. and a reaction step of substituting and introducing a sulfo group into at least part of the hydroxyl groups of the cellulose fibers contained. 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. For example, the mixing ratio described in Examples described later can be used.
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 to be 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. Urea and/or a derivative thereof contained in can be prepared so as to be 1 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, or the reaction liquid and the fiber raw material are dehydrated after being brought into contact with each other. Prepared by filtering, further air-drying the dehydrated and filtered product, further drying the dehydrated and filtered product using a circulating air dryer, and further dewatering and filtering Those prepared by drying using a heating dryer, those prepared by drying the reaction liquid in contact with the fiber raw material using a circulating air dryer or a heating dryer, and so on.
The fiber raw material impregnated with the reaction liquid when subjected to the next reaction step is in a state in which the above-mentioned active water removal is not performed, or in a state in which a certain amount of water is removed by active water removal. You can leave it. 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 fibers contained in the fiber raw material supplied from the contacting step, sulfamic acid, and urea are reacted to substitute the sulfo groups of sulfamic acid for the cellulose hydroxyl groups in the cellulose fibers, This is a step of introducing a sulfo group into the cellulose fibers contained in the fiber raw material. 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 fibers 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 a sulfonation reaction in which the hydroxyl groups of the cellulose fibers in the fiber raw material are substituted with sulfo groups. For example, a method of accelerating the sulfonation reaction by heating the fiber raw material can be employed. 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 sulfo groups can be introduced into the cellulose fibers forming the fiber raw material while suppressing the thermal decomposition and hydrolysis reaction of the fibers.
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. If the ambient temperature during heating is higher than 200° C., thermal decomposition of the fibers may occur, or discoloration of the fibers may accelerate. On the other hand, if 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. can be done. 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 groups can be appropriately introduced into the cellulose fibers as described above. For example, the reaction time in the reaction step is adjusted to 1 minute or more when the reaction temperature is adjusted to fall within 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.
If the reaction time is shorter than 1 minute, it is presumed that the substitution reaction of the sulfo groups with respect to the hydroxyl groups of the cellulose fibers has hardly progressed. On the other hand, 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 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 are no particular restrictions on their 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. In the case of performing such neutralization cleaning, examples of alkaline compounds contained in the alkaline solution include inorganic alkaline compounds and organic alkaline compounds. 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 fed to the micronization step and micronized to obtain 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, a low-pressure homogenizer, a high-pressure homogenizer, a grinder (stone mill type grinder), a ball mill, a cutter mill, a jet mill, a short-screw extruder, a twin-screw extruder, an ultrasonic agitator, a domestic mixer, etc. can be used. , the processing device is not limited to these devices.
Among these, a high-pressure homogenizer is preferable because it can uniformly apply a force to the material and is excellent in homogenization, but it is not limited to such a device.

When using a high-pressure homogenizer in the micronization process, the sulfonated pulp obtained by the above-described manufacturing method 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 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 may be supplied to a processing apparatus such as a high-pressure homogenizer.
For example, when a slurry adjusted to have a sulfonated pulp solid content concentration of 0.5% by mass is supplied to a processing apparatus such as a high-pressure homogenizer, sulfonated fine cellulose fibers having the same solid content concentration are dispersed in the mixed solution. A dispersion of states can be obtained. That is, in this case, it is possible to obtain the fine cellulose fiber-containing composition of the present embodiment in which the solid content concentration of the sulfonated fine cellulose fibers is adjusted to 0.5% by mass.

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.

<Preparation of sulfonated fine cellulose fiber slurry>
(Examples 1, 2, 4)
A softwood kraft pulp sheet (NBKP manufactured by Marusumi Paper Co., Ltd.) was used. Below, the NBKP used in the experiment will be simply described as pulp.
The pulp sheet used was dried to a solid content concentration of 93%, and its basis weight was 3000 g/m ² . A portion of 20 g of this pulp sheet was taken as a solid mass and used for the experiment.

(Chemical treatment process)
The pulp was added to the reaction solution prepared as follows and stirred to form a slurry. The step of adding the pulp to the reaction liquid to form a slurry corresponds to the contacting step of the chemical treatment step of the present embodiment.

(Step of preparing reaction solution)
A sulfonating agent and urea and/or a derivative thereof were prepared so as to have the following solid content concentrations.
In the experiment, sulfamic acid (purity 98.5%, manufactured by Fuso Chemical Industries) was used as the sulfonating agent, and urea solution (purity 99%, manufactured by Wako Pure Chemical Industries, model number; special grade reagent) was used as urea or its derivative. It was used

An example of preparation of the reaction solution is shown below.
85 mL of water was added to the container. Then, 15 g of sulfamic acid and 15 g of urea were added to this container to prepare a reaction solution. That is, urea was added so as to be 100 parts by mass with respect to 100 parts by mass of sulfamic acid.
In the experiment, 20 g of absolute dry pulp was added to the prepared reaction solution. That is, in the case of a reaction solution having a sulfamic acid/urea ratio ((g/L)/(g/L)) of 200/200 (1:1), sulfamic acid is 75 parts by mass per 100 parts by mass of pulp. , Urea was prepared to be 75 parts by mass.
A slurry prepared by adding pulp to the reaction solution is placed in a dryer (manufactured by Isuzu Manufacturing Co., Ltd., model number: VTR-115) in which the temperature of the constant temperature bath is set to 50 ° C. Moisture content (%) obtained from the following formula dried to equilibrium.

The samples were weighed by a measurement method using a weighing bottle. An electronic balance (manufactured by Shinko Denshi Co., Ltd., model number: RJ-320) was used for weighing.

Moisture content (%) = ((mass of sample - mass of solid content of sample) / mass of sample) x 100

Sample: Mass of pulp sample removed from filter paper: Mass (g) of pulp removed from filter paper and dried
Solid content mass of sample: The mass (g) of the pulp stripped from the filter paper was subjected to a dryer, and the same amount of pulp stripped from the filter paper was dried in an atmosphere of 105 ° C. for 2 hours until it reached a constant weight. It is the mass (g) of the solid matter obtained, and the drying method was performed according to JIS P 8225.

It should be noted that drying until the moisture content (%) reaches an equilibrium state was defined as the end point when the moisture in the atmosphere in the treatment facility and the moisture in the sample apparently stopped coming in and out. For example, after drying the sample in a weighing bottle of known mass for a predetermined time, the weighing bottle is capped in the drying apparatus, the sample is removed from the dryer while still in the weighing bottle, and the desiccant is added. After the sample was placed in a desiccator or the like to heat it, the mass of the sample (the mass of the weighing bottle containing the sample - the mass of the weighing bottle) was measured. The end point of drying was a state in which the amount of change in the mass measured twice was within 1% of the mass at the start of drying (however, the second mass measurement was taken after the drying time required for the first time). more than half).

After the moisture content reached an equilibrium state, a heating reaction was carried out.
A dryer (manufactured by Isuzu Manufacturing Co., Ltd., model number: VTR-115) was used for the heating reaction. The reaction conditions are as follows.
Constant temperature bath temperature: 120°C, heating time: 25 minutes After the heat reaction, the reacted pulp is diluted with pure water so that the solid content is 1% by mass or less, and an excess amount of sodium bicarbonate is added. After neutralization, it was thoroughly washed with pure water.
The washed sulfonated pulp was dried until the moisture content reached equilibrium.

(Miniaturization process)

(Preliminary fibrillation treatment)
This dried sulfonated pulp was then subjected to a micronization process.
In the refinement treatment step, the main defibration treatment was performed after performing the preliminary defibration treatment.
The preliminary defibration treatment was carried out for 1 minute with a mixer (fiber mixer MX-X701 manufactured by Panasonic, high speed setting). The conditions at this time were adjusted so that the solid content concentration (% by mass) of the sulfonated pulp in water was 1% by mass. If this pre-fibrillation treatment is carried out as it is, the solid content concentration after main fibrillation will also be 1% by mass.

(Main defibration treatment)
The dispersion obtained by the preliminary fibrillation treatment is fractionated, water and ethanol (corresponding to the water-soluble solvent in the present embodiment) are added to the dispersion, and the main fibrillation treatment is performed to obtain a predetermined mixing ratio (water /ethanol ratio (g/g)) (see figure).

Specifically, preliminarily defibrated pulp was dispersed in a prepared mixed solution of water and ethanol, and the dispersion was subjected to the main fibrillation treatment step.
In this fibrillation, fibrillation treatment (10 times (10 passes) at a fibrillation pressure of 100 MPa) is performed using a high-pressure homogenizer (Yoshida Kikai N2000-2C-045 model), and the sulfonated fine cellulose fibers are mixed with the above mixed solution. A slurry containing sulfonated fine cellulose fibers dispersed in was prepared (Examples 1, 2, 4).
This sulfonated fine cellulose fiber-containing slurry corresponds to the fine cellulose fiber-containing composition of the present embodiment.
For example, the solid content concentration (% by mass) of the sulfonated fine cellulose fibers in the slurry containing the sulfonated fine cellulose fibers of Example 1 is 0.5 mass %.

The solid content concentration of the sulfonated cellulose fine fibers in the slurry containing the sulfonated fine cellulose fibers was calculated by the following formula.

Solid content concentration (% by mass) = (solid content mass (g) of sulfonated fine cellulose fibers)/(mass of slurry containing sulfonated fine cellulose fibers (g)) x 100

(Example 3)
The preparation of the sulfonated fine cellulose fiber slurry of Example 3 was carried out in the same manner as in Example 1 above, except for the method described below.

In 720 mL of pure water, 200 g of sulfamic acid (99.8% purity, manufactured by Fuso Chemical Industries) and 288 g of urea (99.0% purity, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) were completely dissolved (sulfamic acid and The mass ratio of urea is 280 (g/L):400 (g/L)).
Using the entire amount of the above reaction solution, a pulp sheet obtained by drying a NBKP sheet manufactured by Marusumi Paper Co., Ltd. (moisture content: 50%, basis weight: 6000 g/m ² , thickness: 7 mm) in a drier at 105°C until the moisture content is about 1%. 400 g was uniformly impregnated. This impregnated sheet was dried in a drier at 105° C. for 3.5 hours. After that, they were reacted in a drier at 140° C. for 25 minutes. The obtained reactant was passed on a stainless steel sieve with a mesh size of 63 μm (235 mesh), neutralized with a large amount of sodium hydrogen carbonate (purity 99.5%, manufactured by Nacalai Tesque) aqueous solution, and then subjected to a large amount of pure Sulfonated pulp was obtained by washing with water.

Using the obtained sulfonated pulp, a slurry containing sulfonated fine cellulose fibers of Example 3 as shown in FIG. 2 was prepared.

(Example 5)
The preparation of the sulfonated fine cellulose fiber slurry of Example 5 was carried out in the same manner as in Example 1 above, except for the method described below.

200 g of sulfamic acid (purity 99.8%, manufactured by Fuso Chemical Industries) and 500 g of urea (purity 99.0%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number; special grade reagent) were completely dissolved in 1000 mL of pure water (sulfamic acid and The mass ratio of urea is 200 (g/L):500 (g/L)).
2 g of NBKP pulp manufactured by Marusumi Paper Co., Ltd. having a solid content of 10% was added to the prepared reaction solution. That is, in the case of a reaction solution having a sulfamic acid/urea ratio ((g/L)/(g/L)) of 200/500 (1:2.5), sulfamic acid is 1000 parts per 100 parts by mass of pulp. Parts by mass, urea was prepared so as to be 2500 parts by mass. The slurry was suction filtered using filter paper (No. 2). Suction filtration was performed until the solution stopped dripping. After suction filtration, the pulp was peeled off from the filter paper, and the filtered pulp was placed in a drier whose constant temperature bath temperature was set to 50° C. and dried until the moisture content reached an equilibrium state.

After the moisture content reached an equilibrium state, it was placed in a dryer set at 120° C. and heat-reacted for 25 minutes.
After the heat reaction, the reacted pulp was diluted with pure water so that the solid content was 1% by mass or less, neutralized by adding an excess amount of sodium hydrogencarbonate, and thoroughly washed with pure water.
The obtained sulfonated pulp was reacted in the same manner as described above using a reaction solution in which the mass ratio of sulfamic acid and urea was 200 (g/L):500 (g/L). A charred pulp was obtained. This sulfonated pulp having a degree of reactivity of 2 times was reacted again in the same manner as described above using a reaction solution having a mass ratio of sulfamic acid and urea of 200 (g/L):200 (g/L). A sulfonated pulp after the reaction was obtained.

Using the obtained sulfonated pulp after the three-time reaction, pre-fibrillation treatment was performed for 1 minute with a Panasonic fiber mixer (MX-X701, high speed setting), and the obtained dispersion was fractionated. Water and ethanol were added to the dispersion to prepare a predetermined mixing ratio (water/ethanol ratio (g/g)=40/60) (see FIG. 2), and the main defibration treatment was performed. Specifically, the solid content concentration at the time of preliminary fibrillation was set to 1.25% by mass. Then, water and ethanol are added to this pre-fibrillated dispersion to perform the main fibrillation treatment, and the sulfonated fine cellulose of Example 5 having a solid content concentration (mass%) of the sulfonated fine cellulose fibers of 0.5 mass% is obtained. A fiber-containing slurry (see Figure 2) was prepared.

(measurement)

(Measurement of sulfo group introduction amount by electrical conductivity measurement)
The introduction amount of sulfo groups contained in the prepared sulfonated fine cellulose fibers was measured by electrical conductivity measurement.

1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024, manufactured by Organo Co., Ltd.; conditioned) was added to a slurry containing 0.5% by mass of sulfonated fine cellulose fibers (without ethanol). Shake for more than 1 hour (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 the electrical conductivity value was measured while adding 0.5N aqueous sodium hydroxide solution to the slurry containing the 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 inflection point corresponds to the amount of sulfo groups. asked.

(Measurement of haze value and measurement of total light transmittance)
The haze value and the total light transmittance were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model number: SH- 7000). The measurement method was performed according to the method of JIS K 7105.
An optional glass cell (part number: 2277, square cell, optical path length 10 mm×width 40×height 55) of the haze meter filled with pure water was used as a blank measurement value, and the light transmittance of the slurry for measurement 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 values obtained from a control unit of a haze meter (model number CUII, Ver2.00.02).

(B type viscosity measurement)
The viscosity of the prepared slurry containing 0.5% by mass of sulfonated fine cellulose fibers was measured using a Brookfield viscometer.
Measurement conditions, etc. for viscosity measurement are shown below.
B-type viscometer (manufactured by BLOOKFIELD, DV2T (RV type))
Measurement conditions: rotation speed 6 rpm, measurement temperature 20 ° C., measurement time 3 minutes, suitable spindle selected from RV-02 to 07, data recording method is single point Single point is B used in this experiment This is a setting item for the recording method for acquiring only the value at the end of measurement in the viscometer. In other words, the instantaneous value after 3 minutes from the start of measurement is recorded.

(Measurement of thixotropic index)
The thixotropic index (TI value) was determined.
The TI value was calculated by using the Brookfield viscometer described above and measuring at 6 rpm and 60 rpm, and dividing the viscosity value obtained at 6 rpm by the viscosity value obtained at 60 rpm.

<Preparation of paint containing sulfonated fine cellulose fiber slurry>
(Examples 6 and 7)

(Preparation of paint containing sulfonated fine cellulose fiber slurry)

A sulfonated fine cellulose fiber-containing slurry for inclusion in a sulfonated fine cellulose fiber slurry-containing paint was prepared as follows.
The slurry containing sulfonated fine cellulose fibers was prepared in the same manner as in Example 1 above for Example 6 and in Example 2 above, except for the method described below.

In the refining treatment step, after the preliminary defibration treatment is performed at a solid content concentration of 2% by mass, water and ethanol are added so that the solid content concentration of the sulfonated fine cellulose fibers is 1% by mass, and the main defibration treatment is performed. was adjusted to a predetermined mixing ratio (water/ethanol ratio (g/g)) to prepare sulfonated fine cellulose fiber-containing slurries for Examples 6 and 7.

The prepared slurries containing sulfonated fine cellulose fibers were mixed with predetermined coating ingredients to prepare sulfonated fine cellulose fiber slurry-containing coatings (Examples 6 and 7).
The paint containing the sulfonated fine cellulose fiber slurry corresponds to the paint containing the composition containing fine cellulose fibers of the present embodiment.

In the experiment, an acrylic paint (Water Garage Color Clear, manufactured by Asahipen Co., Ltd.) was used as a paint component. The mixing ratio of this acrylic paint and the slurry containing sulfonated fine cellulose fibers was as follows.
In Example 6, the sulfonated fine cellulose fiber-containing slurry prepared in Example 1 and the acrylic paint were prepared at a mass ratio (g/g) of 20 g (sulfonated fine cellulose fiber-containing slurry) and 80 g (acrylic paint), respectively. It was prepared by mixing to be 0.25. That is, the content of the sulfonated fine cellulose fibers in Example 6 was adjusted to 0.2% by mass (the solid content concentration of the sulfonated fine cellulose fibers was 0.2% by mass). The content of sulfonated fine cellulose fibers was calculated using the following formula.

Content of sulfonated fine cellulose fibers in paint (%) = ((sulfonated fine cellulose fibers in slurry containing sulfonated fine cellulose fibers (g))/total amount of paint (g)) x 100 (%)

Example 7 was prepared by mixing 20 g and 80 g of the sulfonated fine cellulose fiber-containing slurry prepared in Example 2 and the acrylic paint, respectively, at a mass ratio (g/g) of 0.25. That is, the content of the sulfonated fine cellulose fibers in Example 7 was adjusted to 0.2% by mass.

(Evaluation and measurement)

(Dispersibility evaluation)
After preparing the slurry containing sulfonated cellulose microfibers, it was visually evaluated whether aggregates (lumps) of sulfonated cellulose fibers were observed in the coating solution.
If no lumps were observed, it was evaluated as ◯; if small lumps were found, Δ;

(Viscosity measurement)
Viscosity was measured using the above-mentioned B-type viscometer after putting the prepared paint in a beaker, tightly covering it with aluminum foil, and allowing it to stand overnight in an environment at 20°C.
The measurement conditions were the same as above.

(Evaluation of quick-drying property of coating film)
Quick-drying properties of the prepared sulfonated fine cellulose fiber slurry-containing paints (Examples 6 and 7) were evaluated.
In the experiment, 0.5 g of each mixture was applied to a cypress wood board, and the change in mass over time was measured. The quick-drying evaluation was performed in a laboratory at room temperature of 20°C and humidity of 40%.
As shown in FIG. 4, if the mass of the coating film after 10 minutes was less than 67% compared to before drying, it was evaluated as ⊚, if it was less than 70% and 67% or more, it was evaluated as ○, and if it was 70% or more, it was evaluated as ×. .

(Strength test of coating film)
The strength of the coating film formed using the prepared sulfonated fine cellulose fiber slurry-containing coating was evaluated.
In the experiment, 5.0 g of a paint containing a slurry of sulfonated fine cellulose fibers was cast on a Teflon sheet (registered trademark), formed into a circle with a diameter of 8 cm, and dried with a blower dryer whose constant temperature bath was set at 50°C. It was dried until it became a coating film. The coating film was pulled by hand to determine the strength of the coating film.
The sample was rated as ⊚ if it was not broken, ∘ if it was broken when it was pulled strongly, and x if it was broken when it was pulled with a light force.

(Examples 8, 9, 10)
In Examples 8, 9, and 10, as shown in FIG. 5, a 1% CNF slurry prepared so that the solid content concentration of the sulfonated fine cellulose fibers was 1% by mass, water, and an acrylic paint were prepared. The procedure was carried out in the same manner as in Example 6 above, except that the mixture was prepared so as to have a mixing ratio of .

The viscosity and TI values in this experiment were measured using the same method as above, as shown in FIG.

In this experiment, dispersion characteristics were evaluated by the following method.
In addition, in FIG. 5, this dispersion characteristic is shown as dispersion maintenance property.
A predetermined amount of the paint containing the prepared sulfonated fine cellulose fiber slurry was dispensed into a transparent test tube (Laboran screw tube bottle manufactured by AS ONE), and after closing the cap, it was shaken well and allowed to stand. At this time, the height of the fractionated liquid from the inner bottom surface of the test tube was 9 cm, which corresponds to the distance of the fractionated liquid fractionated into the test tube in the following formula. Immediately after standing, the acrylic paint was evenly dispersed to form an emulsion in all cases including the comparative examples. That is, immediately after shaking, the water and the acrylic paint were homogeneously mixed and no interface was formed between them. In other words, if the state after standing still for a predetermined time is the same as the state immediately after shaking, it can be said that the dispersion characteristics are excellent.
After standing for 48 hours, the state of the emulsion was confirmed, and when an interface was formed between the two, the dispersion characteristics (%) were evaluated according to the following formula. When the emulsion state after shaking was maintained and no interface was formed, the dispersibility was taken as 100%. The distance in the following formula means the distance between the bottom surface and the top surface of the liquid.

Dispersion characteristic (%) is calculated by the following formula.

Dispersion characteristics (%) = (distance cm of emulsion-formed part)/(distance cm of sampled liquid collected in test tube) x 100.

For example, when a test tube has a transparent portion at the top and an emulsion (emulsion-forming portion) at the bottom, the bottom surface of the emulsion-forming portion (equivalent to the inner bottom surface of the test tube) and the top surface of the emulsion-forming portion (between the emulsion-forming portion and the transparent portion) The distance between the interfaces) was measured and taken as the distance cm of the emulsion forming part.

Comparative Examples 14 to 17 used phosphate groups, and Comparative Examples 17 to 20 were blanks to which fine cellulose fibers were not added.

(Examples 11, 12, 13)
In Examples 11, 12, and 13, as shown in FIG. 6, a 0.5% CNF slurry prepared so that the solid content concentration of the sulfonated fine cellulose fibers was 0.5% by mass was used instead of the acrylic paint. Using a lotion (a commercially available lotion containing sebum-adsorbing ingredients (the sebum-adsorbing ingredients form precipitates when left standing)), prepare a cosmetic containing a sulfonated fine cellulose fiber slurry at a predetermined mixing ratio. Then, the viscosity characteristics and dispersion characteristics were evaluated. Viscosity properties were evaluated in the same manner as in Example 8 above.
In addition, in FIG. 6, this dispersion characteristic is shown as dispersion maintenance property.

In the evaluation of the dispersion characteristics in this experiment, Labcon's centrifuge tube Super Seal Cap was used as the test tube, the stationary time was set to 24 hours, and the amount of the fractionated liquid was set to a height of 6 cm from the inner bottom surface of the test tube. , the dispersion characteristics were evaluated in the same manner as in Example 8, except that the state of the interface was evaluated as follows.

It is calculated by the following formula of dispersion characteristics (%) in this experiment.

Dispersion characteristic (%) = (Distance cm of fractionated liquid fractionated in test tube - Distance cm of transparent part) / (Distance cm of fractionated liquid fractionated into test tube) x 100

For example, when the test tube has a transparent part in the upper part and an emulsion (emulsion-forming part) in the lower part, there is a gap between the bottom surface of the transparent part (interface between the emulsion-forming part and the transparent part) and the upper surface of the transparent part (equivalent to the upper surface inside the test tube). The distance was measured and taken as the transparent part distance (cm).
When the emulsion state after shaking is maintained and no interface is formed, the distance of the transparent portion is 0 cm and the dispersion characteristic is 100%.

(Comparative Example 1, Comparative Examples 5-7)
Comparative Example 1 was prepared in the same manner as Examples 1, 2 and 4, except that the water/ethanol ratio (g/g) was adjusted to 100/0.
Comparative Example 5 was the same as the sulfonated fine cellulose fibers used in Examples 1, 2 and 4, except that the amount of sulfo groups introduced into the sulfonated fine cellulose fibers was adjusted to 0.3 mmol/g. gone. Also, the water/ethanol ratio (g/g) was adjusted to 60/40.
Comparative Example 6 was the same as the sulfonated fine cellulose fibers used in Examples 1, 2 and 4, except that the sulfonated fine cellulose fibers were prepared so that the amount of sulfo groups introduced was 0.6 mmol/g. gone. Also, the water/ethanol ratio (g/g) was adjusted to 40/60.
Comparative Example 7 was prepared in the same manner as Examples 1, 2 and 4, except that the water/ethanol ratio (g/g) was adjusted to 40/60.

(Comparative Examples 2-4)
In Comparative Examples 2 to 4, slurries containing phosphate-esterified fine cellulose fibers were prepared in which phosphoric acid groups were introduced instead of sulfo groups.

In a beaker, 11.2 g of ammonium dihydrogen phosphate (purity 99.0%, manufactured by Fujifilm Wako Pure Chemical Industries, model number; special grade reagent), urea (purity 99.0%, manufactured by Fujifilm Wako Pure Chemical Industries, model number; Special grade reagent) was weighed out, 80 mL of pure water was added, and the mixture was stirred to prepare a phosphoric acid esterification solution.

(Phosphate esterification of pulp)
The raw material, dry pulp, was prepared as follows.
A softwood kraft pulp sheet (NBKP sheet manufactured by Marusumi Paper Co., Ltd.) was used. Below, the NBKP used in the experiment will be simply described as pulp.
The pulp sheet used was dried to a moisture content of 7% and had a basis weight of 3000 g/m2.

Phosphate esterified pulp was produced as follows.
5 g (solid mass) of the prepared pulp was placed in a beaker, and 100 g of the phosphating solution was added. After allowing the pulp to absorb the solution well, it was spread on an aluminum vat and placed in a dryer at 80° C. to dry water until the moisture content reached 5% or less. After that, it was placed in a dryer under an atmosphere of 160° C. to 180° C. and reacted for 25 minutes. After that, it is poured onto a stainless steel sieve with a mesh size of 63 μm (235 mesh), neutralized with sodium hydrogen carbonate (purity 99.5%, manufactured by Nacalai Tesque) as a neutralizing agent, and then washed with a large amount of pure water. After washing, the pulp was dried until the moisture content reached an equilibrium state to obtain a phosphate esterified pulp.

The resulting phosphate ester pulp was micronized under the same conditions as in the method for preparing the sulfonated fine cellulose fibers to prepare slurries containing phosphate ester fine cellulose fibers (Comparative Examples 2 to 4).

(Comparative Examples 8-13)
Comparative Examples 8 to 13 were prepared as comparative examples of paints.
Comparative Example 8 was prepared by mixing 20 g and 80 g, respectively, of the slurry containing sulfonated fine cellulose fibers prepared in Comparative Example 1 and the acrylic paint at a mass ratio (g/g) of 0.25. That is, the content of the sulfonated fine cellulose fibers in Comparative Example 8 was adjusted to 0.2% by mass.
Comparative Example 9 was prepared by mixing 20 g and 80 g, respectively, of the phosphoric esterified fine cellulose fiber-containing slurry prepared in Comparative Example 2 and the acrylic paint at a mass ratio (20 g/80 g) of 0.25.
Comparative Example 10 was prepared by mixing 20 g and 80 g, respectively, of the phosphoric esterified fine cellulose fiber-containing slurry prepared in Comparative Example 3 and the acrylic paint at a mass ratio (20 g/80 g) of 0.25.
Comparative Example 11 was prepared by mixing 20 g and 80 g of the slurry containing phosphoric esterified fine cellulose fibers prepared in Comparative Example 2 and the acrylic paint in a mass ratio (20 g/80 g) of 0.25.
Comparative Example 12 was prepared by mixing 20 g and 80 g of the slurry containing phosphoric esterified fine cellulose fibers prepared in Comparative Example 3 and the acrylic paint at a mass ratio (20 g/80 g) of 0.25.
Comparative Example 13 was prepared by mixing 20 g and 80 g of water (pure water) and acrylic paint, respectively, at a mass ratio (20 g/80 g) of 0.25.

In Comparative Examples 14, 15, and 16, the same measurements and measurements as in Example 8 were performed, except that the slurry containing phosphorylated esterified fine cellulose fibers prepared in Comparative Example 3 was used as 1% CNF, and the blending ratio in FIG. made an evaluation.

Comparative Examples 17 to 20 were measured and evaluated in the same manner as in Example 8, except that they were adjusted to the blend ratio shown in FIG. 5 without containing fine cellulose fibers.

Comparative Examples 21, 22, and 23 were the same as Example 11, except that the phosphorylated esterified fine cellulose fiber-containing slurry prepared in Comparative Example 3 was used as 0.5% CNF, and the blending ratio in FIG. 6 was prepared. Measurements and evaluations were made.

Comparative Example 24 was measured and evaluated in the same manner as in Example 11, except that it was adjusted to the blend ratio shown in FIG. 6 without containing fine cellulose fibers.

Each characteristic (physical property) of the comparative example was measured by the same method as the above example. Results are shown in the figure.

The experimental results of Examples 1-7 are shown in FIGS. 1-4.
1 and 2 are tables showing properties (physical properties) of slurries containing sulfonated fine cellulose fibers.
3 and 4 are tables showing the properties (physical properties) of paints containing sulfonated fine cellulose fiber-containing slurries.

As shown in FIGS. 1 and 2, the sulfonated fine cellulose fiber-containing slurry had high transparency and predetermined viscosity characteristics. From the results of Comparative Example 1, it can be seen that the sulfonated fine cellulose fibers contained in the slurry containing sulfonated fine cellulose fibers are fibers having a structure exhibiting transparency.
In addition, it had excellent transparency and viscosity as compared with the slurry containing phosphate-esterified fine cellulose fibers of the comparative example.

As shown in FIG. 2, when the amount of sulfo groups introduced was small, even defibration treatment could not be performed (Comparative Example 5). On the other hand, by increasing the amount of sulfo groups introduced, excellent transparency and viscosity were obtained even when the concentration of ethanol was increased (Example 5). In other words, it was confirmed that the greater the amount of sulfo groups, the more the transparency (that is, the dispersibility of the sulfonated fine cellulose fibers) could be maintained even when the ethanol ratio in the water/ethanol solution was increased.
As shown in FIG. 2, in Example 3 and Comparative Example 6, the amount of sulfo groups introduced was the same, but the former (water/ethanol is 60/40) was able to be defibrated. In contrast, the latter (40/60 water/ethanol) could not be defibrated. Similarly, in Example 4 and Comparative Example 7, the amount of sulfo groups introduced is the same, but in the former (water/ethanol is 60/40) and the latter (water/ethanol is 40/60), the former is It shows high transparency (that is, it shows that a sulfonated fine cellulose fiber with a structure having dispersibility is obtained) and shows appropriate viscosity characteristics, whereas the latter shows a defibration treatment. Although it could be done, the transparency was poor (ie no suitable sulfonated microcellulose fibers could be prepared) and the viscosity properties could not be properly measured.
In other words, when the amount of sulfo groups introduced is 1.3 mmol/g or less, the defibration treatment tends to be difficult to perform in a slurry state in which the ratio of ethanol is higher than that of water. It has also been found to be difficult to prepare the desired sulfonated fine cellulose fibers.

In addition, as shown in FIG. 3, it was confirmed that the film produced using the slurry containing sulfonated fine cellulose fibers had high transparency.

　From the results of Figures 1 and 2, as the amount of ethanol increased, the dispersion state of the fine cellulose fibers varied according to each functional group. Compared to the phosphate group, the sulfo group was able to maintain transparency even when the ratio of water in the mixed solution was changed. This suggests that the sulfo group is more effective in improving the dispersibility of fine cellulose fibers than the phosphate group.

As shown in Figure 3, the paint containing the slurry containing sulfonated fine cellulose fibers had superior properties compared to the comparative example. In particular, when only water was mixed with the acrylic paint, there was a tendency for the fine cellulose fibers to aggregate and form lumps in the paint. However, almost no lumps were observed by mixing a slurry containing sulfonated fine cellulose fibers dispersed in a mixed solution of water and ethanol with the acrylic paint.
From these facts, since the mixed solution mixed with ethanol has a high affinity with the paint component, if the sulfonated fine cellulose fibers are uniformly dispersed in the ethanol mixed solution (slurry containing sulfonated fine cellulose fibers is transparent If it is in a good state, that is, if the haze value is low), even if it is mixed with a paint component such as an acrylic paint, it is considered that both can be mixed appropriately.
Moreover, as shown in FIG. 4, it was confirmed that quick-drying property (handleability) can be improved because the paint contains volatile ethanol. In other words, it was confirmed that the use of the paint of the present invention could improve the coatability and handleability while containing fine cellulose fibers.

The experimental results of Examples 8-10 are shown in FIG.
In the coating liquids containing no fine cellulose fibers (Comparative Examples 18 to 20), water and coating components are separated, whereas in the coating containing the sulfonated fine cellulose fiber slurry of the present invention, the coating component (acrylic coating) is separated. It was confirmed that there was no separation, that is, the dispersion characteristics were 100%.
Moreover, the sulfonated fine cellulose fiber slurry-containing paints of Examples 8 to 10 have excellent dispersion characteristics compared to the fine cellulose fiber-containing paints (Comparative Examples 14 to 16) in which phosphoric acid groups are introduced instead of sulfo groups. It was confirmed that it works.
In addition, the paints containing the sulfonated fine cellulose fiber slurry of Examples 8-10 have similar viscosities to the paints of Comparative Examples 14-16, and while exhibiting a predetermined TI value, they have an appropriate dispersion. It was confirmed that the properties (a state in which the sulfonated fine cellulose fibers are appropriately dispersed) are exhibited.

Therefore, the coating composition containing the sulfonated fine cellulose fiber slurry of the present invention has excellent dispersion characteristics (coating components are uniformly It was confirmed that the state of being dispersed in) was exhibited. Therefore, it was confirmed that the use of the coating composition containing the sulfonated fine cellulose fiber slurry of the present invention enables the formation of a coating film in which the components of the coating composition are homogeneously contained. In addition, it was confirmed that the low viscosity and the predetermined TI value can be exhibited, so that the handleability as a paint can be improved. On the other hand, in the paints of Comparative Examples 14 to 16, the dispersion characteristics are lower than the paint containing the sulfonated fine cellulose fiber slurry of the present invention, so the paint component in the paint film contains the sulfonated fine cellulose fiber slurry of the present invention. It was found that the homogeneity was reduced compared to the coating film of the paint.

The experimental results of Examples 11-13 are shown in FIG.
In the cosmetic liquid containing no fine cellulose fibers (Comparative Example 24), the cosmetic components separated to form precipitates, whereas in the cosmetic liquid containing the sulfonated fine cellulose fiber slurry of Examples 11 and 12, the cosmetic No sedimentation of the components occurred, and it was confirmed that even the cosmetic containing the sulfonated fine cellulose fiber slurry of Example 13 exhibited a dispersibility of 70% or more.
Moreover, the cosmetic compositions containing sulfonated fine cellulose fiber slurries of Examples 11 to 13 had excellent dispersion compared to cosmetic liquids containing fine cellulose fibers (Comparative Examples 21 to 23) in which phosphoric acid groups were introduced instead of sulfo groups. It was confirmed that the characteristics were exhibited.
Moreover, it was confirmed that the sulfonated fine cellulose fiber slurry-containing cosmetic materials of Examples 11 to 13 could have a lower viscosity than those of Comparative Examples 21 to 23, and exhibited a predetermined TI value.

Therefore, the sulfonated fine cellulose fiber slurry-containing paint of this experiment contains sulfonated fine cellulose fibers having a predetermined structure (a structure that exhibits a predetermined transparency), so that it has excellent dispersion characteristics (cosmetic ingredients are dispersed homogeneously). It was confirmed that the state of being dispersed in) was exhibited.
Therefore, by including the fine cellulose fiber-containing composition of the present invention in a cosmetic, a cosmetic composition that tends to precipitate can be maintained in a homogeneous state at all times. Since even a cosmetic composition that is easy to apply can be appropriately applied, the effect of the cosmetic can be appropriately exhibited.
In addition, in the case of cosmetics that tend to form sediment, it is necessary to shake them thoroughly before use so that the sediments are in a homogeneous state. may not be possible. However, if such a cosmetic contains the fine cellulose fiber-containing composition of the present invention, the effect of the cosmetic can be appropriately exhibited without performing such operations immediately before use.

The composition containing fine cellulose fibers and the thickening agent of the present invention are used for dispersing fine cellulose fibers in various fields such as the medical field, food field, environmental field, industrial field, and papermaking field. Suitable as a sticky agent. Moreover, the paint of the present invention can be widely used in environmental fields, industrial fields, etc., as it exhibits the properties of fine cellulose fibers.

Claims

A composition used for the target liquid,
Some of the hydroxyl groups dispersed in water, a water-soluble solvent, and a mixed solution of the water-soluble solvent and water are substituted with sulfo groups, and the introduction amount of the sulfo groups is 0.4 mmol/g to 3.0 mmol/g. sulfonated fine cellulose fibers of
A composition containing fine cellulose fibers, wherein the sulfonated fine cellulose fibers have a haze value of 30% or less when the solid content concentration of the sulfonated fine cellulose fibers is 0.5% by mass.
The water content is
20 parts by mass to 300 parts by mass with respect to 1 part by mass of the sulfonated fine cellulose fibers,
The content of the water-soluble solvent is
2. The fine cellulose fiber-containing composition according to claim 1, wherein the amount is 10 to 300 parts by mass with respect to 100 parts by mass of the water.
The sulfonated fine cellulose fibers have a solid content concentration of 0.5% by mass, and are measured using a Brookfield viscometer at 20° C. at 6 rpm and 60 rpm to calculate the respective viscosities. 3. The fine cellulose fiber-containing composition according to claim 1 or 2, wherein the thixotropic index calculated from each viscosity ratio (viscosity at 6 rpm/viscosity at 60 rpm) is 5.0 or more Composition.
4. The composition containing fine cellulose fibers according to claim 1, 2 or 3, wherein the water-soluble solvent is a lower alcohol.
5. The composition containing fine cellulose fibers according to claim 1, 2, 3 or 4, wherein the sulfonated fine cellulose fibers have an average fiber width of 2 nm or more and 30 nm or less.
6. The fine cellulose fiber-containing fiber according to claim 1, 2, 3, 4 or 5, wherein the sulfonated fine cellulose fiber has an aspect ratio (average fiber length/average fiber width) of 20 or more and 1000 or less. Composition.
7. The composition containing fine cellulose fibers according to any one of claims 1 to 6, wherein the target liquid is paint.
7. The composition containing fine cellulose fibers according to any one of claims 1 to 6, wherein the target liquid is an external preparation for skin.
7. The composition containing fine cellulose fibers according to any one of claims 1 to 6, wherein the target liquid is a cosmetic.
7. The composition containing fine cellulose fibers according to any one of claims 1 to 6, wherein the target liquid is a thickening agent.
A paint containing the fine cellulose fiber-containing composition according to any one of claims 1 to 6,
A paint, wherein the content of sulfonated fine cellulose fibers in the composition containing fine cellulose fibers in the paint is 0.05% by mass to 10% by mass.
The solid content concentration of the sulfonated fine cellulose fibers is 0.1% by mass to 1.0% by mass, and the viscosity measured using a Brookfield viscometer under the conditions of 20° C., 6 rpm, and 3 minutes is , 100 mPa·s or more and 4000 mPa·s or less.
Using a B-type viscometer, the solid content concentration of the sulfonated fine cellulose fibers is 0.1% by mass to 1.0% by mass. 12. The thixotropic index calculated from each viscosity ratio (viscosity at 6 rpm/viscosity at 60 rpm) is 2.0 or more. Paint as described.
A thickener containing the fine cellulose fiber-containing composition according to any one of claims 1 to 6,
A thickening agent characterized in that the content of the sulfonated fine cellulose fibers is 0.1% by mass to 95% by mass relative to the total amount of the thickening agent.