JP2022063104A - Dispersion - Google Patents

Abstract

To provide a dispersion having microfibrous cellulose dispersed in organic solvent, the dispersion having high thixotropy.SOLUTION: A dispersion contains fibrous cellulose with a fiber width of 1000 nm or less and an organic solvent. The fibrous cellulose has anionic groups, with the content of the anionic groups being 0.50 mmol/g or more. The fibrous cellulose has organic onium ions as counterions of the anionic groups. The dispersion has a B viscosity of 50 Pa s or more as measured by Measurement method (A).SELECTED DRAWING: None

Description

The present invention relates to a dispersion. Specifically, the present invention relates to a dispersion containing fine fibrous cellulose and an organic solvent.

Conventionally, cellulose fibers have been widely used in clothing, absorbent articles, paper products and the like. As the cellulose fiber, in addition to the fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Fine fibrous cellulose is attracting attention as a new material, and its uses are wide-ranging. For example, sheets containing fine fibrous cellulose, resin complexes, and thickeners are being developed.

In general, since fine fibrous cellulose is stably dispersed in an aqueous solvent, it is provided in the form of an aqueous dispersion and is often used for various purposes. On the other hand, when producing a complex or the like by mixing fine fibrous cellulose with a resin component, there is also a demand that fine fibrous cellulose should be mixed with an organic solvent and used. As a technique for meeting such a demand, a technique for producing a fine fibrous cellulose-containing dispersion liquid in which fine fibrous cellulose is dispersed in a dispersion medium containing an organic solvent has been studied (Patent Documents 1 to 4).

For example, Patent Documents 1 to 3 disclose fine fibrous cellulose composites in which a surfactant is adsorbed on fine fibrous cellulose having a carboxyl group. Here, a method of finely dividing the cellulose fibers in an aqueous solvent and then aggregating the fine fibrous cellulose and dispersing it in an organic solvent, or a method of obtaining fine fibrous cellulose by finely dividing the cellulose fibers in an organic solvent are used. It has been disclosed. Further, Patent Document 4 discloses a composition for spraying, which comprises a hydrophobically modified cellulose fiber in which a modifying group is bonded to one or more selected from an anionic group and a hydroxyl group of the cellulose fiber, and an organic medium. ing.

Japanese Unexamined Patent Publication No. 2011-140738 Japanese Unexamined Patent Publication No. 2016-188375 Japanese Unexamined Patent Publication No. 2019-49091 Japanese Unexamined Patent Publication No. 2020-76054

The dispersion liquid obtained by dispersing fine fibrous cellulose in an organic solvent has various uses. For example, in the use of paints and the like, the dispersion liquid may be required to have high thixotropy.

Therefore, in order to solve the problems of the prior art, the present inventors have determined to provide a dispersion liquid obtained by dispersing fine fibrous cellulose in an organic solvent and having high thixotropy. We proceeded with the examination as a purpose.

As a result of diligent studies to solve the above problems, the present inventors have found that an anion of fine fibrous cellulose in a dispersion liquid containing fine fibrous cellulose having an anionic group in a predetermined amount or more and an organic solvent. It has been found that a dispersion having high thixotropy can be obtained by introducing an organic onium ion as a counterion of a sex group and further setting the B-type viscosity measured under predetermined conditions to 50 Pa · s or more.
Specifically, the present invention has the following configurations.

[1] A dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less and an organic solvent.
The fibrous cellulose has an anionic group, and the content of the anionic group is 0.50 mmol / g or more.
Fibrous cellulose has organic onium ions as counterions of anionic groups and has
A dispersion having a B-type viscosity of 50 Pa · s or more measured by the following measuring method (A);
Measurement method (A):
The B-type viscosity when the fibrous cellulose concentration of the dispersion is 3% by mass (w / w), the rotation speed is 0.6 rpm, and the temperature is 23 ° C. is measured according to JIS Z 8803 (2011). ..
[2] The dispersion liquid according to [1], wherein the light transmittance measured by the following measurement method (B) is 80% or more;
Measurement method (B):
The fibrous cellulose concentration of the dispersion is set to 3% by mass (w / w), the mixture is encapsulated in a quartz cell having an optical path length of 10 mm, and the light transmittance at a wavelength of 660 nm is measured using an ultraviolet / visible spectrophotometer.
[3] The dispersion liquid according to [1] or [2], wherein the fiber width of the fibrous cellulose is 10 nm or less.
[4] The anionic group is at least one selected from the group consisting of a phosphoric acid group, a substituent derived from a phosphoric acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group, [1]. ] To [3].

According to the present invention, it is possible to obtain a dispersion liquid obtained by dispersing fine fibrous cellulose in an organic solvent and having high thixotropy.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped and the pH of a fibrous cellulose-containing slurry having a phosphoric acid group. FIG. 2 is a graph showing the relationship between the amount of NaOH dropped and the pH with respect to the fibrous cellulose-containing slurry having a carboxy group.

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

(Dispersion)
The present invention relates to a dispersion containing fibrous cellulose having a fiber width of 1000 nm or less and an organic solvent. Here, the fibrous cellulose has an anionic group, and the content of the anionic group is 0.50 mmol / g or more. In addition, fibrous cellulose has an organic onium ion as a counterion of an anionic group. The B-type viscosity of the dispersion measured by the following measuring method (A) is 50 Pa · s or more.
Measurement method (A):
The B-type viscosity when the fibrous cellulose concentration of the dispersion is 3% by mass (w / w), the rotation speed is 0.6 rpm, and the temperature is 23 ° C. is measured according to JIS Z 8803 (2011). .. The B-type viscosity of the dispersion is preferably the viscosity of the dispersion composed of an organic solvent and fibrous cellulose.

The B-type viscosity of the dispersion liquid measured by the above-mentioned measuring method (A) of the dispersion liquid of the present embodiment may be 50 Pa · s or more, preferably 55 Pa · s or more, and is 60 Pa · s or more. It is more preferably 70 Pa · s or more, further preferably 80 Pa · s or more, further preferably 90 Pa · s or more, and particularly preferably 100 Pa · s or more. The upper limit of the B-type viscosity of the dispersion liquid measured by the above-mentioned measuring method (A) of the dispersion liquid is not particularly limited, but is preferably 500 Pa · s or less, for example.

Since the dispersion liquid of the present invention has the above-mentioned structure, it has high thixotropy. That is, the dispersion liquid of the present invention has a property that the viscosity is lowered by applying a share. The thixotropy of the dispersion can be evaluated, for example, by the TI value calculated by the following formula.
TI value = (viscosity value at 0.6 rpm / viscosity value at 60 rpm)
Here, the value of the viscosity at 0.6 rpm is the B type when an organic solvent dispersion having a fibrous cellulose concentration of 3% by mass was allowed to stand at 23 ° C. for 24 hours and then rotated at 0.6 rpm for 3 minutes. Viscosity value. The viscosity value at 60 rpm is the value of the B-type viscosity when the organic solvent dispersion having a fibrous cellulose concentration of 3% by mass was allowed to stand at 23 ° C. for 24 hours and then rotated at 60 rpm for 3 minutes. .. The B-type viscosity is measured using a B-type viscometer, and as the B-type viscometer, for example, an analog viscometer T-LVT manufactured by BLOOKFIELD can be used.

The TI value of the dispersion calculated by the above method is preferably 20.0 or more, more preferably 30.0 or more, further preferably 40.0 or more, and 50.0 or more. It is more preferable to have. The upper limit of the TI value of the dispersion liquid is not particularly limited, but is preferably 500 or less, for example.

The light transmittance measured by the following measuring method (B) of the dispersion liquid in the present embodiment is preferably 80% or more, more preferably 84% or more, still more preferably 88% or more. It is particularly preferable that it is 90% or more.
Measurement method (B):
The fibrous cellulose concentration of the dispersion is set to 3% by mass (w / w), the mixture is encapsulated in a quartz cell having an optical path length of 10 mm, and the light transmittance at a wavelength of 660 nm is measured using an ultraviolet / visible spectrophotometer. As the ultraviolet / visible spectroscopic analyzer, for example, V-770 manufactured by JASCO Corporation can be used. The zero point measurement is performed with ion-exchanged water contained in the same glass cell.

(Organic solvent)
The dispersion liquid of the present invention contains an organic solvent. The dispersion liquid of the present invention is a fine fibrous cellulose-containing dispersion liquid in which fine fibrous cellulose described later is dispersed in a dispersion medium containing an organic solvent. The dispersion liquid of the present invention may further contain water in addition to the organic solvent as the dispersion medium, but the content of water with respect to the total mass of the dispersion liquid is preferably 5% by mass or less. It is more preferably 1% by mass or less, and further preferably 1% by mass or less. In the present embodiment, it is preferable that the dispersion medium contains substantially no water, and it is particularly preferable that the content of water with respect to the total mass of the dispersion liquid is 0% by mass.

The relative permittivity of the organic solvent of the dispersion liquid at 25 ° C. is preferably 60 or less, more preferably 50 or less. Since the fibrous cellulose contained in the dispersion liquid can exhibit excellent dispersibility even in an organic solvent having a low relative permittivity, the relative permittivity of the organic solvent at 25 ° C. may be 45 or less. , 40 or less, or 35 or less.

The δd of the Hansen solubility parameter (HSP) of the organic solvent is preferably 5 MPa ^1/2 or more and 20 MPa ^1/2 or less, and preferably 10 MPa ^1/2 or more and 19 MPa ^1/2 or less. Further, δh is preferably 1 MPa ^1/2 or more and 40 MPa ^1/2 or less, and more preferably 2 MPa ^1/2 or more and 30 MPa ^1/2 or less. It is also preferable that δp is in the range of 0 MPa ^1/2 or more and 4 MPa ^1/2 or less, and δh is in the range of 0 MPa ^1/2 or more and 6 MPa ^1/2 or less at the same time.

Examples of the organic solvent include methanol (relative permittivity 32.6), ethanol (relative permittivity 24.3), n-propyl alcohol (relative permittivity 20.1), isopropyl alcohol (IPA) (relative permittivity 18). .62), 1-butanol (relative permittivity 18), m-cresol (relative permittivity 11.8), glycerin (relative permittivity 42.5), acetic acid (relative permittivity 6.15), pyridine (relative permittivity) Relative permittivity 12.3), permittivity (THH) (relative permittivity 7.5), acetone (relative permittivity 20.7), methyl ethyl permittivity (MEK) (relative permittivity 15.45), ethyl acetate (relative permittivity 6.). 4), aniline (relative permittivity 6.89), N-methyl-2-pyrrolidone (NMP) (relative permittivity 32.2), dimethylsulfxide (DMSO) (relative permittivity 45), N, N-dimethylformamide (DMF) (relative permittivity 38), hexane (relative permittivity 1.8), cyclohexane (relative permittivity 2.0), benzene (relative permittivity 2.3), toluene (relative permittivity 2.4), p-xylene (relative permittivity 2.3), styrene (relative permittivity 2.3-3.4), diethyl ether (relative permittivity 4.3), chloroform (relative permittivity 4.8), etc. be able to. Among them, the organic solvent is preferably at least one selected from the group consisting of toluene, xylene and styrene.

The content of the organic solvent is preferably 10% by mass or more, more preferably 50% by mass or more, based on the total mass of the solid content contained in the dispersion liquid. The content of the organic solvent is preferably 99.9% by mass or less, more preferably 99.0% by mass or less, and 95 by mass, based on the total mass of the solid content contained in the dispersion liquid. It is more preferably 0.0% by mass or less.

(Fine fibrous cellulose)
The dispersion liquid of the present invention contains fibrous cellulose having a fiber width of 1000 nm or less. The fiber width of the fibrous cellulose is preferably 100 nm or less, more preferably 50 nm or less, further preferably 20 nm or less, further preferably 10 nm or less, and particularly preferably 8 nm or less. preferable. In the present specification, fibrous cellulose having a fiber width of 1000 nm or less is also referred to as fine fibrous cellulose.

The average fiber width of the fibrous cellulose is, for example, 1000 nm or less. The average fiber width of the fibrous cellulose is, for example, preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more and 10 nm or less. Especially preferable. The fibrous cellulose is, for example, monofibrous cellulose.

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

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

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

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

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

The axial ratio (fiber length / fiber width) of the fibrous cellulose is not particularly limited, but is preferably 20 or more and 10000 or less, and more preferably 50 or more and 1000 or less. By setting the axial ratio to the above lower limit value or more, it is easy to form a sheet containing fine fibrous cellulose. Further, by setting the axial ratio to the above upper limit value or less, it is preferable in that handling such as dilution becomes easy when, for example, fibrous cellulose is treated as a dispersion liquid.

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

Fibrous cellulose has an anionic group. Examples of the anionic group include a phosphorusoxo acid group or a substituent derived from a phosphoroxo acid group (sometimes referred to simply as a phosphorusoxo acid group), a carboxy group or a substituent derived from a carboxy group (sometimes simply referred to as a carboxy group), and the like. And a sulfur oxo acid group or a substituent derived from the sulfur oxo acid group (sometimes simply referred to as a sulfur oxo acid group) and the like can be mentioned. Among them, the anionic group is preferably at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. More transparent when the anionic group is at least one selected from the group consisting of a phosphooxo acid group, a substituent derived from a phospho oxo acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group. It is easy to obtain a highly viscous dispersion.

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

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

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

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

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

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

Specific examples of the phosphoric acid group or the substituent derived from the phosphoric acid group include a phosphoric acid group (-PO ₃ H ₂ ), a salt of a phosphoric acid group, and a phosphite group (phosphonic acid group) (-PO). _{2H 2 )} , a salt of a phosphite group (phosphonic acid group) can be mentioned. Further, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a group in which a phosphoric acid group is condensed (for example, a pyrophosphate group), a group in which a phosphonic acid is condensed (for example, a polyphosphonic acid group), and a phosphoric acid ester group (for example, a phosphoric acid ester group). For example, it may be a monomethyl phosphate group, a polyoxyethylene alkyl phosphate group), an alkylphosphonic acid group (for example, a methylphosphonic acid group), or the like.

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

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

The content (introduction amount) of the anionic group may be, for example, 0.50 mmol / g or more per 1 g (mass) of fibrous cellulose, more preferably 0.60 mmol / g or more, and 0.80 mmol / g. The above is more preferable, and 1.00 mmol / g or more is particularly preferable. The content (introduction amount) of the anionic group is, for example, preferably 5.20 mmol / g or less per 1 g (mass) of fibrous cellulose, and more preferably 3.65 mmol / g or less. It is more preferably 00 mmol / g or less, further preferably 2.50 mmol / g or less, and particularly preferably 2.00 mmol / g or less. Here, the denominator in the unit mmol / g indicates the mass of the fibrous cellulose when the counterion of the anionic group is a hydrogen ion (H ⁺ ). By setting the introduction amount of the anionic group within the above range, the content of organic onium ions that can be contained in the fibrous cellulose can be set within an appropriate range, whereby the dispersibility of the fibrous cellulose in an organic solvent can be improved. It can be enhanced more effectively.

The amount of anionic groups introduced into the fibrous cellulose can be measured, for example, by a neutralization titration method. In the measurement by the neutralization titration method, the introduction amount is measured by determining the change in pH while adding an alkali such as an aqueous sodium hydroxide solution to the obtained slurry containing fibrous cellulose.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped and the pH of a fibrous cellulose-containing slurry having a phosphoric acid group. The amount of the phosphorus oxo acid group introduced into the fibrous cellulose is measured, for example, as follows.
First, the slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the same defibration treatment as the defibration treatment step described later may be performed on the measurement target before the treatment with the strong acid ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 1 is obtained. The titration curve shown in the upper part of FIG. 1 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 1 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, two points are confirmed in which the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid of the fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the first end point to the second end point. The amount is equal to the amount of the second dissociated acid of the fibrous cellulose contained in the slurry used for the titration, and the amount of alkali required from the start to the second end point of the titration is the fibrous cellulose contained in the slurry used for the titration. Is equal to the total amount of dissociated acid. Then, the value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol / g). The amount of phosphorus oxo acid group introduced (or the amount of phosphorus oxo acid group) simply means the amount of the first dissociated acid.
In FIG. 1, the region from the start of titration to the first end point is referred to as a first region, and the region from the first end point to the second end point is referred to as a second region. For example, when the phosphoric acid group is a phosphoric acid group and the phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently. It decreases, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so that the amount of alkali required for the second region is reduced or the amount of alkali required for the second region is reduced. May be zero. In this case, there is only one point on the titration curve where the pH increment is maximum.

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

FIG. 2 is a graph showing the relationship between the amount of NaOH dropped and the pH of a dispersion liquid containing fibrous cellulose having a carboxy group as an anionic group. The amount of the carboxy group introduced into the fibrous cellulose is measured, for example, as follows.
First, the dispersion liquid containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the same defibration treatment as the defibration treatment step described later may be performed on the measurement target before the treatment with the strong acid ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 2 is obtained. The titration curve shown in the upper part of FIG. 2 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 2 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, in the curve plotting the pH measured with respect to the amount of alkali added, one point was confirmed where the increment (differential value of pH with respect to the amount of alkali dropped) became maximum, and this maximum point was the first. Called one end point. Here, the region from the start of titration to the first end point in FIG. 2 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the dispersion used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the dispersion liquid containing the fibrous cellulose to be titrated, so that the amount of carboxy group introduced (mmol). / G) is calculated.

Since the denominator of the above-mentioned carboxy group introduction amount (mmol / g) is the mass of the acid type fibrous cellulose, the carboxy group amount of the acid type fibrous cellulose (hereinafter, the carboxy group amount (acid type)). ) Is shown. On the other hand, when the counterion of the carboxy group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of fibrous cellulose when the cation C is a counterion. Therefore, the amount of carboxy group (hereinafter, the amount of carboxy group (C type)) possessed by the fibrous cellulose in which the cation C is a counter ion can be obtained. That is, it is calculated by the following formula.
Amount of carboxy group (C type) = Amount of carboxy group (acid type) / {1+ (W-1) x (amount of carboxy group (acid type)) / 1000}
W: Formulated amount of cation C per valence (for example, Na is 23, Al is 9).

In the measurement of the amount of anionic groups by the titration method, accurate values can be obtained, such as when the amount of one drop of sodium hydroxide aqueous solution is too large, or when the titration interval is too short, the amount of anionic groups is lower than originally intended. Sometimes not. As an appropriate dropping amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of a 0.1 N sodium hydroxide aqueous solution every 5 to 30 seconds. Further, in order to eliminate the influence of carbon dioxide dissolved in the fibrous cellulose-containing slurry, for example, it is desirable to measure while blowing an inert gas such as nitrogen gas into the slurry from 15 minutes before the start of titration to the end of titration.

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

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

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

<Linoxo acid group introduction process>
The process for producing fine fibrous cellulose includes an anionic group introduction step. Examples of the anionic group introduction step include a phosphorus oxo acid group introduction step. In the phosphorus oxo acid group introduction step, at least one compound (hereinafter, also referred to as “compound A”) selected from compounds capable of introducing a phosphorus oxo acid group by reacting with a hydroxyl group of a fiber raw material containing cellulose is used as cellulose. It is a step of acting on a fiber raw material containing. By this step, a phosphorus oxo acid group-introduced fiber can be obtained.

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

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

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

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

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

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

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

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

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

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

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

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

The amount of the phosphorus oxo acid group introduced into the fiber raw material may be, for example, 0.50 mmol / g or more per 1 g (mass) of the fiber raw material, more preferably 0.60 mmol / g or more, and 0.80 mmol / g or more. It is more preferable that the amount is 1.00 mmol / g or more, and it is particularly preferable that the amount is 1.00 mmol / g or more. The content (introduction amount) of the phosphorus oxo acid group is, for example, preferably 5.20 mmol / g or less per 1 g (mass) of fibrous cellulose, more preferably 3.65 mmol / g or less. It is more preferably 00 mmol / g or less, further preferably 2.50 mmol / g or less, and particularly preferably 2.00 mmol / g or less. By setting the amount of the phosphorus oxo acid group introduced within the above range, the content of organic onium ions that can be contained in the fibrous cellulose can be set within an appropriate range, whereby the dispersibility of the fibrous cellulose in an organic solvent can be improved. It can be enhanced more effectively.

<Carboxy group introduction process>
The process for producing fine fibrous cellulose may include, for example, a carboxy group introduction step as the anionic group introduction step. The carboxy group introduction step has an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a group derived from carboxylic acid or a derivative thereof, or a group derived from carboxylic acid with respect to the fiber raw material containing cellulose. It is carried out by treatment with an acid anhydride of a compound or a derivative thereof.

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

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

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

The amount of the carboxy group introduced into the fiber raw material varies depending on the type of the substituent. For example, when the carboxy group is introduced by TEMPO oxidation, it may be 0.50 mmol / g or more per 1 g (mass) of the fiber raw material. It is more preferably 60 mmol / g or more, further preferably 0.80 mmol / g or more, and particularly preferably 1.00 mmol / g or more. The amount of the carboxy group introduced into the fibrous cellulose is preferably 3.65 mmol / g or less, more preferably 3.00 mmol / g or less, and further preferably 2.50 mmol / g or less. , 2.00 mmol / g or less is more preferable. In addition, when the substituent is a carboxymethyl group, the amount of the carboxy group introduced may be 5.8 mmol / g or less per 1 g (mass) of the fine fibrous cellulose. By setting the introduction amount of the carboxy group within the above range, the content of organic onium ions that can be contained in the fine fibrous cellulose can be set within an appropriate range, whereby the dispersibility of the fibrous cellulose in an organic solvent can be improved. It can be enhanced more effectively.

<Sulfur oxoacid group introduction process>
The process for producing fine fibrous cellulose may include, for example, a sulfur oxoacid group introduction step as an anionic group introduction step. In the sulfur oxoacid group introduction step, a cellulose fiber having a sulfur oxoacid group (sulfur oxoacid group-introduced fiber) can be obtained by reacting the hydroxyl group of the fiber raw material containing cellulose with sulfur oxoacid.

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

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

In the heat treatment step, it is preferable to heat until the water content is substantially eliminated. Therefore, the heat treatment time varies depending on the amount of water contained in the cellulose raw material and the amount of the aqueous solution containing sulfur oxoacid and urea and / or a urea derivative, but is, for example, 10 seconds or more and 10,000 seconds or less. It is preferable to do so. Equipment having various heat media can be used for the heat treatment, for example, a hot air drying device, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, and a fluidized layer drying device. , Band type drying device, filtration drying device, vibration flow drying device, air flow drying device, vacuum drying device, infrared heating device, far infrared heating device, microwave heating device, high frequency drying device can be used.

The amount of sulfur oxoacid group introduced into the cellulose raw material may be 0.50 mmol / g or more per 1 g (mass) of fibrous cellulose, more preferably 0.60 mmol / g or more, and 0.80 mmol / g or more. Is more preferable, and 1.00 mmol / g or more is particularly preferable. The amount of sulfur oxoacid group introduced is preferably 5.00 mmol / g or less, and more preferably 3.00 mmol / g or less per 1 g (mass) of fibrous cellulose. By setting the introduction amount of the sulfur oxoacid group within the above range, the content of the organic onium ion that can be contained in the fine fibrous cellulose can be set within an appropriate range, whereby the dispersion of the fibrous cellulose with respect to the organic solvent can be achieved. Sex can be enhanced more effectively.

<Washing process>
In the method for producing fine fibrous cellulose in the present embodiment, a washing step can be performed on the anionic group-introduced fiber, if necessary. The washing step is performed by washing the anionic group-introduced fiber with, for example, water or an organic solvent. Further, the cleaning step may be performed after each step described later, and the number of cleaning steps performed in each cleaning step is not particularly limited.

<Alkaline treatment process>
In the case of producing fine fibrous cellulose, an alkali treatment may be performed on the fiber raw material between the anionic group introduction step and the defibration treatment step described later. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the anionic group-introduced fiber in an alkaline solution.

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

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time of the anionic group-introduced fiber in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the anionic group-introduced fiber. Is more preferable.

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

<Acid treatment process>
In the case of producing fine fibrous cellulose, an acid treatment may be performed on the fiber raw material between the step of introducing an anionic group and the defibration treatment step described later. For example, the anionic group introduction step, the acid treatment, the alkali treatment and the defibration treatment may be performed in this order.

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

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

<Defibration processing process>
Fine fibrous cellulose can be obtained by defibrating the anionic group-introduced fiber in the defibration treatment step. In the defibration processing step, for example, a defibration processing apparatus can be used. The defibration processing device is not particularly limited, but is, for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, and a twin shaft. A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, a beater, or the like can be used. Among the above-mentioned defibration processing devices, it is more preferable to use a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by pulverized media and have less risk of contamination.

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

The solid content concentration of the fine fibrous cellulose during the defibration treatment can be appropriately set. Further, the slurry obtained by dispersing the anionic group-introduced fiber in a dispersion medium may contain a solid content other than the anionic group-introduced fiber such as urea having a hydrogen bond property.

(Organic onium ion)
Fine fibrous cellulose contains organic onium ions as counterions of anionic groups. In the present embodiment, at least a part of the organic onium ion is present as a counter ion of the fibrous cellulose, but the free organic onium ion may be present in the dispersion liquid. The organic onium ion does not form a covalent bond with the fibrous cellulose.

The organic onium ion preferably satisfies at least one of the conditions selected from the following (a) and (b).
(A) Contains a hydrocarbon group having 5 or more carbon atoms.
(B) The total number of carbon atoms is 17 or more.
That is, the fibrous cellulose contains at least one selected from an organic onium ion containing a hydrocarbon group having 5 or more carbon atoms and an organic onium ion having a total carbon number of 17 or more as a counterion of an anionic group. Is preferable. By satisfying at least one of the conditions selected from the above (a) and (b) for the organic onium ion, the dispersibility of the fine fibrous cellulose in the organic solvent can be more effectively enhanced.

The hydrocarbon group having 5 or more carbon atoms is preferably an alkyl group having 5 or more carbon atoms or an alkylene group having 5 or more carbon atoms, and an alkyl group having 6 or more carbon atoms or an alkylene group having 6 or more carbon atoms. It is more preferably a group, more preferably an alkyl group having 7 or more carbon atoms or an alkylene group having 7 or more carbon atoms, and an alkyl group having 10 or more carbon atoms or an alkylene group having 10 or more carbon atoms. It is particularly preferable to have. Among them, the organic onium ion preferably has an alkyl group having 5 or more carbon atoms, and more preferably an organic onium ion having an alkyl group having 5 or more carbon atoms and having a total carbon number of 17 or more. preferable.

The organic onium ion is preferably an organic onium ion represented by the following general formula (A).

In the above general formula (A), M is referred to as a central element of an organic onium ion. M is preferably a nitrogen atom or a phosphorus atom. Further, R ₁ to R ₄ independently represent a hydrogen atom or an organic group, respectively. However, it is preferable that at least one of R ₁ to R ₄ is an organic group having 5 or more carbon atoms, or the total number of carbon atoms of R ₁ to R ₄ is 17 or more.
Above all, M is preferably a nitrogen atom. That is, the organic onium ion is preferably an organic ammonium ion. Further, it is preferable that at least one of R ₁ to R ₄ is an alkyl group having 5 or more carbon atoms, and the total number of carbon atoms of R ₁ to R ₄ is 17 or more.

Examples of the organic onium ion include lauryltrimethylammonium, cetyltrimethylammonium, stearyltrimethylammonium, octyldimethylethylammonium, lauryldimethylethylammonium, didecyldimethylammonium, lauryldimethylbenzylammonium, tributylbenzylammonium, and methyltri-n-octylammonium. , Hexylammonium, n-octylammonium, dodecylammonium, tetradecylammonium, hexadecylammonium, stearylammonium, N, N-dimethyldodecylammonium, N, N-dimethyltetradecylammonium, N, N-dimethylhexadecylammonium, N , N-dimethyl-n-octadecylammonium, dihexylammonium, di (2-ethylhexyl) ammonium, din-octylammonium, didecylammonium, didodecylammonium, didecylmethylammonium, N, N-didodecylmethylammonium, poly Oxyethylene dodecylammonium, alkyldimethylbenzylammonium, di-n-alkyldimethylammonium, behenyltrimethylammonium, tetraphenylphosphonium, tetraoctylphosphonium, acetonyltriphenylphosphonium, allyltriphenylphosphonium, amyltriphenylphosphonium, benzyltriphenylphosphonium , Ethyltriphenylphosphonium, diphenylpropylphosphonium, triphenylphosphonium, tricyclohexylphosphonium, tri-n-octylphosphonium and the like. Examples of the alkyl group in alkyldimethylbenzylammonium and di-n-alkyldimethylammonium include linear alkyl groups having 8 or more and 18 or less carbon atoms.

As shown in the general formula (A), the central element of the organic onium ion is bonded to a total of four groups or hydrogen. In the name of the above-mentioned organic onium ion, when the number of bonded groups is less than four, the remaining hydrogen atoms are bonded to form an organic onium ion. For example, in the case of N, N-didodecylmethylammonium, it can be determined from the name that two dodecyl groups and one methyl group are bonded. In this case, hydrogen is bonded to the remaining one to form an organic onium ion.

When the organic onium contains O atoms, the larger the mass ratio (C / O ratio) of C atoms to O atoms is, the more preferable, for example, C / O> 5. By increasing the C / O ratio to more than 5, a fibrous cellulose concentrate can be obtained when an organic onium ion or a compound that forms an organic onium ion by neutralization is added to the fine fibrous cellulose-containing slurry. It will be easier.

The molecular weight of the organic onium ion is preferably 2000 or less, and more preferably 1800 or less. By setting the molecular weight of the organic onium ion within the above range, the handleability of the fibrous cellulose can be improved. Further, by setting the molecular weight of the organic onium ion within the above range, it is possible to suppress a decrease in the content of fibrous cellulose in the dispersion liquid.

The content of the organic onium ion is preferably 0.5 times to 2 times the molar amount with respect to the anionic group amount contained in the fine fibrous cellulose, but is not particularly limited. The content of organic onium ions can be measured by tracking the atoms typically contained in organic onium ions. Specifically, when the organic onium ion is an ammonium ion, the nitrogen atom is measured, and when the organic onium ion is a phosphonium ion, the amount of the phosphorus atom is measured. When the fine fibrous cellulose contains nitrogen atoms and phosphorus atoms in addition to the organic onium ions, the amount of the target atoms is determined after performing a method for extracting only the organic onium ions, for example, an extraction operation with an acid. Just measure.

The organic onium ion is preferably an ion exhibiting hydrophobicity. That is, the fine fibrous cellulose in the present embodiment exhibits hydrophobicity by having organic onium ions. As a result, dispersibility in an organic solvent is enhanced, and a dispersion liquid exhibiting a desired viscosity and light transmittance can be obtained. And, such a dispersion liquid can exhibit high thixotropy property.

(Optional ingredient)
The dispersion liquid of the present embodiment may be a dispersion liquid composed of the above-mentioned fine fibrous cellulose and an organic solvent, but may contain an arbitrary component in addition to the above-mentioned fine fibrous cellulose and an organic solvent. .. As the optional component, for example, a resin can be mentioned. The type of resin is not particularly limited, and examples thereof include thermoplastic resins and thermosetting resins.

As the resin, acrylic resin, polycarbonate resin, polyester resin, polyamide resin, silicone resin, fluororesin, chlorine resin, epoxy resin, melamine resin, phenol resin, polyurethane resin, diallyl phthalate. Examples thereof include based resins, alcohol-based resins, cellulose derivatives, and precursors of these resins. Examples of the cellulose derivative include carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and the like.

The dispersion liquid may contain a precursor of the resin as the resin. The type of resin precursor is not particularly limited, and examples thereof include precursors of thermoplastic resins and thermosetting resins. The precursor of a thermoplastic resin means a monomer or an oligomer having a relatively low molecular weight used for producing a thermoplastic resin. Further, the precursor of a thermosetting resin means a monomer or an oligomer having a relatively low molecular weight that can cause a polymerization reaction or a cross-linking reaction by the action of light, heat, or a curing agent to form a thermosetting resin.

The dispersion liquid may further contain a water-soluble polymer as the resin in addition to the above-mentioned resin species. Examples of the water-soluble polymer include synthetic water-soluble polymers (for example, carboxyvinyl polymer, polyvinyl alcohol, alkyl methacrylate / acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, polyethylene glycol, diethylene glycol, triethylene glycol, propylene). Glycer, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide, etc., thickening polysaccharides (eg, xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seeds) , Arginic acid, purulan, carrageenan, pectin, etc.), cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, starches such as amylose, glycerin such as glycerin, diglycerin, polyglycerin, etc., hyaluronic acid , Metallic salts of hyaluronic acid and the like.

In addition, as optional components, surfactants, organic ions, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, preservatives, defoamers, organic particles, lubricants, antistatic agents, ultraviolet protective agents, etc. Examples thereof include dyes, pigments, stabilizers, magnetic powders, orientation promoters, plasticizers, dispersants, and cross-linking agents.

(Manufacturing method of dispersion)
The method for producing the dispersion is to add an organic onium ion or a compound that forms an organic onium ion by neutralization to a fine fibrous cellulose-containing slurry obtained through the above-mentioned defibration step to obtain a fibrous cellulose aggregate (a fibrous cellulose aggregate (). It includes a step of obtaining a concentrate) and a step of dispersing the fibrous cellulose aggregate (concentrate) in an organic solvent.

In the step of obtaining the fibrous cellulose aggregate (concentrate), the above-mentioned organic onium ion or the organic onium ion is formed by neutralization in the fine fibrous cellulose-containing slurry obtained in the above-mentioned defibration treatment step. Add the compound. At this time, the organic onium ion is preferably added as a solution containing the organic onium ion, and more preferably added as an aqueous solution containing the organic onium ion.

An aqueous solution containing organic onium ions usually contains organic onium ions and a counterion (anion). When preparing an aqueous solution of organic onium ions, if the organic onium ions and the corresponding counterions have already formed a salt, they may be dissolved in water as they are. When preparing an aqueous solution of organic onium ions, it is preferable to dissolve them in water or hot water if the organic onium ions and the corresponding counterions have already formed a salt.

In addition, organic onium ions may be produced only after being neutralized by an acid, for example, dodecylamine. In this case, the organic onium ion is obtained by the reaction of the compound forming the organic onium ion by neutralization with the acid. In this case, examples of the acid used for neutralization include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as lactic acid, acetic acid, formic acid and oxalic acid. In the aggregation step, a compound that forms organic onium ions by neutralization may be directly added to the fibrous cellulose-containing slurry, and the anionic group contained in the fibrous cellulose may be used as a counterion to ionize the organic onium.

The amount of the organic onium ion added is preferably 2% by mass or more, more preferably 10% by mass or more, still more preferably 50% by mass or more, more preferably 100% by mass, based on the total mass of the fibrous cellulose. It is particularly preferable that it is by mass or more. The amount of organic onium ion added is preferably 1000% by mass or less with respect to the total mass of the fibrous cellulose.
The number of moles of the organic onium ion to be added is preferably 0.2 times or more, preferably 0.5 times or more the value obtained by multiplying the amount (number of moles) of the inorganic oxo acid groups contained in the fibrous cellulose by the valence. The above is more preferable, and 1.0 times or more is further preferable. The number of moles of the organic onium ion to be added is preferably 10 times or less the value obtained by multiplying the amount (number of moles) of the inorganic oxoacid group contained in the fibrous cellulose by the valence.

When organic onium ions are added and stirred, aggregates are formed in the fibrous cellulose-containing slurry. This agglomerate is an agglomerate of fibrous cellulose having an organic onium ion as a counterion. As used herein, such aggregates are also referred to as fibrous cellulose concentrates. The fibrous cellulose aggregate (concentrate) can be recovered by filtering the fibrous cellulose-containing slurry in which the agglomerates are generated under reduced pressure.

The obtained fibrous cellulose aggregate may be washed with ion-exchanged water. By repeatedly washing the fibrous cellulose aggregate with ion-exchanged water, excess organic onium ions and the like contained in the fibrous cellulose aggregate can be removed.

The solid content concentration of the obtained fibrous cellulose aggregate is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 25% by mass or more. The solid content concentration of the fibrous cellulose aggregate may be 100% by mass.

The water content of the fibrous cellulose agglomerates may be 0% by mass, 0.5% by mass or more, or 1% by mass or more, based on the total mass of the fibrous cellulose agglomerates. It may be 3% by mass or more, and may be 5% by mass or more. The water content of the fibrous cellulose agglomerates is preferably 20% by mass or less, more preferably 15% by mass or less, based on the total mass of the fibrous cellulose agglomerates. The water content in the fibrous cellulose agglomerates can be measured by placing 200 mg of the fibrous cellulose agglomerates on a moisture meter (MS-70, manufactured by A & D Co., Ltd.) and heating at 140 ° C. can. The water content in the fibrous cellulose aggregate can be calculated from the measured water content.

The fibrous cellulose agglomerates can be further dried, aged, spray-dried, granulated, sheeted, heated, wetted, crushed, sprayed, soaked, filtered, frozen, sublimated, etc. It may have undergone a water extraction step, a pressure dehydration step, a centrifugal dehydration step, a surface treatment step, or the like. Above all, the fibrous cellulose agglomerates are preferably those that have undergone a drying step, whereby fibrous cellulose agglomerates having a low water content can be obtained.

In the step of dispersing the fibrous cellulose aggregate (concentrate) in an organic solvent, the fibrous cellulose agglomerate (concentrate) obtained in the above-mentioned step of obtaining the fibrous cellulose agglomerate (concentrate) is used as an organic solvent. Disperse. Since such a dispersion step is a step of redispersing the fibrous cellulose aggregate (concentrate) in the solvent, it is also called a redispersion step.

As the dispersant used for dispersing the fibrous cellulose aggregate (concentrate) in the organic solvent, for example, the same disperser as the defibration treatment device described in the above defibration treatment can be used. Above all, when the fibrous cellulose aggregate (concentrate) is dispersed in an organic solvent, it is preferable to disperse it using a high-pressure homogenizer or an ultra-high pressure homogenizer. By using a high-pressure homogenizer in the redispersion step, the redispersibility of the fibrous cellulose aggregate (concentrate) is enhanced, and a highly viscous and highly transparent dispersion can be easily obtained.

Further, in the redispersion step or before the redispersion step, it is preferable to provide a step of heating the suspension obtained by dispersing the fibrous cellulose aggregate (concentrate) in an organic solvent. That is, the method for producing the dispersion liquid is a step of adding an organic onium ion or a compound that forms an organic onium ion by neutralization to a fine fibrous cellulose-containing slurry to obtain a fibrous cellulose aggregate (concentrate). , A step of suspending a fibrous cellulose aggregate (concentrate) in an organic solvent to obtain a suspension, and a step of heating the suspension and treating it with a high-pressure homogenizer or an ultra-high-pressure homogenizer to obtain a dispersion. , Are preferably included. In this case, the suspension is preferably heated to 40 ° C. or higher. In the heating step, the temperature of the suspension is preferably 100 ° C. or lower. Conventionally, in the redispersion step, cooling has usually been performed for the purpose of suppressing heat denaturation of the fibrous cellulose aggregate (concentrate). However, in the present embodiment, it is decided to intentionally provide a heating step in the redispersion step or before the redispersion step. By providing such a heating step, we have succeeded in obtaining a highly viscous and highly transparent dispersion.

When the suspension is heated in the redispersion step or before the redispersion step, the liquid temperature after passing through the disperser is preferably 40 ° C. or higher. When a high-pressure homogenizer or an ultra-high-pressure homogenizer is used as the disperser, it is preferable that the liquid temperature after passing through the crushing mechanism portion is 40 ° C. or higher. In order to raise the liquid temperature to 40 ° C or higher after passing through the disperser, for example, increasing the pressure when passing through the disperser, reducing the inner diameter of the internal flow path of the crushing processing unit, increasing the pump speed, and passing through the pump. The preheating and / or after passing through the pump and / or the pulverizing treatment unit, preheating the suspension to be tested, and the like can be mentioned.

In the present specification, the step of preheating the suspension to be tested may be referred to as a preheating step. In the preheating step, it is preferable to heat the suspension so that the liquid temperature is 40 ° C. or higher and 100 ° C. or lower. In the present embodiment, it is preferable to provide such a preheating step, and the suspension before the high-pressure homogenizer treatment is preheated to 40 ° C. or higher to disperse the fine fibrous cellulose in an organic solvent. The properties are further improved, and a highly viscous and highly transparent dispersion liquid can be easily obtained.

The step of producing the dispersion may further include a step of dispersing an arbitrary component in the obtained dispersion. Examples of the optional component used at this time include the above-mentioned optional component.

(Use)
The dispersion liquid of the present invention may be used for various purposes as a thickener. For example, the dispersion liquid of the present invention is added to foods, cosmetics, cement, paints (for vehicle painting of automobiles, ships, aircraft, etc., for building materials, daily necessities, etc.), inks, pharmaceuticals, packaging materials, coating materials, etc. It can be used as a thing. Further, the dispersion liquid of the present invention can be applied to daily necessities by adding it to a resin-based material. Above all, the dispersion liquid of the present invention is preferably used for paints.

Further, the dispersion liquid of the present invention is preferably used for forming a molded body. The shape of the molded body is not particularly limited, and for example, a sheet-shaped, granular, or thread-shaped molded body can be used. Above all, the dispersion liquid of the present invention is preferably used for applications of sheet-shaped molded products. For example, the dispersion liquid of the present invention can be formed into a film and used as various films.

The molded product obtained by applying the dispersion liquid on the base material is a reinforcing material, an interior material, an exterior material, a packaging material, an electronic material, an optical material, an acoustic material, a process material, a member of a transportation device, and an electronic device. It is also suitable for applications such as members of the above and members of electrochemical elements.

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

<Manufacturing example A>
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 g / m ² sheets, separated and measured according to JIS P 8121, Canadian standard drainage degree (CSF) is 700 ml) It was used. The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphate group into the cellulose in the pulp to obtain a phosphorylated pulp.

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

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

The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption of the phosphate group based on P = O was observed near 1230 cm ^-1 , and it was confirmed that the phosphate group was added to the pulp. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration (fibrous cellulose concentration) of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion A containing fine fibrous cellulose.

By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. The fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 2 to 5 nm. Further, when 100 fine fibrous celluloses were extracted from the image analysis by AFM and the number average value of the aspect ratio was calculated, the number average value of the aspect ratio was 300. The amount of phosphoric acid group (first dissociated acid amount) measured by the method for measuring the amount of phosphoric acid group described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mol / g.

<Manufacturing example B>
Using 33 parts by mass of phosphorous acid (phosphonic acid) instead of ammonium dihydrogen phosphate, the procedure was the same as in Production Example A, except that a phosphorous acid group was introduced into the cellulose in the pulp, and subphosphorylation was performed. Obtained pulp.

The infrared absorption spectrum of the obtained subphosphorylated pulp was measured using FT-IR. As a result, absorption based on P = O of the phosphonic acid group, which is a metamorphic form of the phosphorous acid group, was observed near 1210 cm ^-1 , and the phosphorous acid group (phosphonic acid group) was added to the pulp. Was confirmed. In addition, when the obtained subphosphorylated pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals.

The obtained subphosphorylated pulp was treated with a wet atomizing apparatus in the same manner as in Production Example A to obtain a fine fibrous cellulose dispersion B containing fine fibrous cellulose.

By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. The fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 3 to 5 nm. Further, when 100 fine fibrous celluloses were extracted from the image analysis by AFM and the number average value of the aspect ratio was calculated, the number average value of the aspect ratio was 280. The amount of phosphorous acid group (first dissociated acid amount) measured by the method for measuring the amount of phosphorous acid group described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example C>
The same procedure as in Production Example A was carried out except that 38 parts by mass of amide sulfuric acid was used instead of ammonium dihydrogen phosphate to obtain sulfated pulp.

The infrared absorption spectrum of the sulfated pulp thus obtained was measured using FT-IR. As a result, absorption based on a sulfate group (sulfonic acid group) was observed in the vicinity of 1220-1260 cm ^-1 , and it was confirmed that a sulfate group (sulfonic acid group) was added to the pulp. Further, when the obtained sulfated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

Ion-exchanged water was added to the obtained sulfated pulp and then stirred to prepare a slurry having a solid content concentration (fibrous cellulose concentration) of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion C containing fine fibrous cellulose. Further, when 100 fine fibrous celluloses were extracted from the image analysis by AFM and the number average value of the aspect ratio was calculated, the number average value of the aspect ratio was 280. The amount of sulfate group (sulfonic acid group) measured by the method for measuring the amount of sulfur oxoacid group described later was 1.30 mmol / g.

<Manufacturing example D>
As the raw material pulp, softwood kraft pulp (undried) made by Oji Paper was used. The raw material pulp was subjected to alkaline TEMPO oxidation treatment as follows. First, the above raw pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10,000 parts by mass of water. It was dispersed in the department. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so as to be 10 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change was observed in the pH.

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

Further, when the obtained TEMPO oxide pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration (fibrous cellulose concentration) of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion D containing fine fibrous cellulose.

By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. The fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 2 to 5 nm. Further, when 100 fine fibrous celluloses were extracted from the image analysis by AFM and the number average value of the aspect ratio was calculated, the number average value of the aspect ratio was 250. The amount of carboxy group measured by the method for measuring the amount of carboxy group described later was 1.80 mmol / g.

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

[Measurement of carboxy group amount]
In the measurement of the carboxy group amount of the fine fibrous cellulose, first, ion-exchanged water was added to the target fine fibrous cellulose to prepare a slurry having a solid content concentration of 0.2% by mass. The obtained fine fibrous cellulose dispersion was treated with an ion exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 was added to the fine fibrous cellulose dispersion, and the mixture was shaken for 1 hour. After that, it was poured on a mesh having an opening of 90 μm to separate the resin and the slurry.
For titration using alkali, add 50 μL of a 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose dispersion treated with an ion exchange resin once every 30 seconds at the pH indicated by the dispersion. This was done by measuring the change in value. For the carboxy group amount (mmol / g), the alkali amount (mmol) required in the region corresponding to the first region shown in FIG. 2 of the measurement results is divided by the solid content (g) in the slurry to be titrated. Calculated.

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

<Example 1>
When 100 g of a 3.86 mass% di-n-stearyldimethylammonium chloride (hereinafter, also referred to as DDMA) aqueous solution was added to 100 g of the fine fibrous cellulose dispersion A and stirred for 5 minutes, the fine fibrous cellulose dispersion was stirred. Aggregates were formed inside. The fine fibrous cellulose dispersion in which the agglomerates were formed was filtered under reduced pressure to obtain fine fibrous cellulose agglomerates. By repeatedly washing the obtained fine fibrous cellulose aggregate with ion-exchanged water, excess di-n-stearyldimethylammonium chloride and eluted ions contained in the fine fibrous cellulose aggregate are removed, and the fine fibrous cellulose is removed. A concentrate was obtained. The obtained fine fibrous cellulose concentrate was air-dried to obtain a fine fibrous cellulose concentrate A having a solid content concentration of 90% by mass.

Toluene was added to the fine fibrous cellulose concentrate A so that the solid content concentration (fibrous cellulose concentration) was 3% by mass to prepare a suspension. Further, this suspension was preheated in a hot water bath, and the temperature of the suspension was set to 40 ° C. The suspension preheated to 40 ° C. was treated with a high-pressure homogenizer (Beryu-Mini, manufactured by Bitsubu Co., Ltd.) 5 times at a pressure of 100 MPa. At this time, the liquid temperature after passing through the pulverization processing section was measured. In this way, a toluene dispersion of the fine fibrous cellulose concentrate A was obtained.

The toluene dispersion obtained above was allowed to stand at 23 ° C. for 24 hours, and then the viscosity was measured using a B-type viscometer (analog viscometer T-LVT manufactured by BLOOKFIELD). The measurement conditions were 23 ° C., and the viscosity when rotated at 0.6 rpm or 60 rpm for 3 minutes was measured. In addition, the TI value, which is an index of thixotropic property, was calculated according to the following formula.
TI value = (viscosity value at 0.6 rpm / viscosity value at 60 rpm)

The toluene dispersion obtained above is enclosed in a quartz glass cell for liquid with an optical path length of 10 mm, and the light transmittance at a wavelength of 660 nm is measured using an ultraviolet / visible spectroscopic analyzer (V-770, manufactured by Nippon Spectroscopy Co., Ltd.). bottom. The zero point measurement was performed with ion-exchanged water contained in the same glass cell. In addition, the light transmittance was measured immediately after redispersing in an organic solvent in each Example and Comparative Example.

<Example 2>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that the fine fibrous cellulose dispersion B was used.

<Example 3>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that the fine fibrous cellulose dispersion C was used.

<Example 4>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that preheating was not performed before the treatment with the high-pressure homogenizer.

<Example 5>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that the fine fibrous cellulose dispersion D was used.

<Example 6>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that xylene was used instead of toluene.

<Example 7>
An organic solvent dispersion was obtained in the same manner as in Example 1 except that didecyldimethylammonium chloride (hereinafter, also referred to as DDDMA) was used instead of di-n-stearyldimethylammonium chloride.

<Comparative Example 1>
The organic solvent dispersion was prepared in the same manner as in Example 1 except that the toluene suspension was treated for 10 minutes using an ultrasonic homogenizer (HIELSCHER, UP400S) instead of the high-pressure homogenizer without preheating. Obtained.

The dispersion obtained in the examples had high viscosity and high transparency, and the thixotropic property was improved. Further, in Examples 1 to 3, 5 and 6, the viscosity and transparency were further improved by setting the liquid temperature immediately after the high-pressure homogenizer pulverization treatment to 40 ° C. or higher.

Claims (4)

A dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less and an organic solvent.
The fibrous cellulose has an anionic group, and the content of the anionic group is 0.50 mmol / g or more.
The fibrous cellulose has an organic onium ion as a counterion of the anionic group and has an organic onium ion.
A dispersion having a B-type viscosity of 50 Pa · s or more measured by the following measuring method (A);
Measurement method (A):
The B-type viscosity when the fibrous cellulose concentration of the dispersion is 3% by mass (w / w), the rotation speed is 0.6 rpm, and the temperature is 23 ° C. is measured according to JIS Z 8803 (2011). do. The dispersion liquid according to claim 1, wherein the light transmittance measured by the following measurement method (B) is 80% or more;
Measurement method (B):
The fibrous cellulose concentration of the dispersion is set to 3% by mass (w / w), the mixture is encapsulated in a quartz cell having an optical path length of 10 mm, and the light transmittance at a wavelength of 660 nm is measured using an ultraviolet / visible spectrophotometer. The dispersion liquid according to claim 1 or 2, wherein the fibrous cellulose has a fiber width of 10 nm or less. The anionic group is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group, claims 1 to 1. The dispersion liquid according to any one of 3.

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