JP7127005B2 - Fine fibrous cellulose inclusions - Google Patents

Description

The present invention relates to fine fibrous cellulose inclusions. Specifically, the present invention relates to fine fibrous cellulose inclusions comprising fine fibrous cellulose having phosphate groups and groups having urethane linkages.

BACKGROUND ART In recent years, attention has been paid to materials using reproducible natural fibers due to the replacement of petroleum resources and the growing awareness of the environment. Among natural fibers, fibrous cellulose having a fiber diameter of 10 to 50 μm, particularly wood-derived fibrous cellulose (pulp) has been widely used mainly as paper products.

As fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Sheets and composites containing fine fibrous cellulose have significantly increased contact points between fibers, resulting in greatly improved tensile strength. In addition, since the fiber width is shorter than the wavelength of visible light, the transparency is greatly improved. For example, Patent Literature 1 discloses a fiber-reinforced composite material that maintains high transparency without being affected by temperature conditions, wavelengths, etc., and is provided with various functionalities by combining fibers with a matrix material. It is It is also known that fine fibrous cellulose can be used for applications such as thickening agents.

Fine fibrous cellulose can be produced by mechanically treating conventional cellulose fibers, but the cellulose fibers are strongly bonded to each other by hydrogen bonding. Therefore, a mere mechanical treatment requires a huge amount of energy to obtain fine fibrous cellulose.

It is well known that pretreatment such as chemical treatment or biological treatment is effective in combination with mechanical treatment in order to produce fine fibrous cellulose with less mechanical treatment energy. In particular, when hydrophilic functional groups (e.g., carboxyl groups, cationic groups, phosphate groups, etc.) are introduced into the hydroxyl groups on the surface of cellulose by chemical treatment, electrical repulsion occurs between ions, and ions are hydrated. By doing so, the dispersibility in an aqueous solvent is remarkably improved. For this reason, the energy efficiency of miniaturization is higher than when no chemical treatment is applied.

For example, Patent Document 2 discloses a method of oxidizing hydroxyl groups of cellulose to carboxyl groups by TEMPO-catalyzed oxidation and then refining the cellulose. In Patent Document 3, a cationizing agent having a reactive functional group such as a quaternary ammonium group and an epoxy group is reacted with an alkali-activated cellulose fiber to modify the hydroxyl group into an ether having cationic properties, and then refine it. A method for doing so is disclosed.

Further, Patent Documents 4 to 10 disclose techniques relating to fine fibrous cellulose in which a phosphoric acid group forms an ester with a hydroxyl group of cellulose. Patent Document 10 discloses that the phosphate group-introducing step is performed in the presence of urea.

Japanese Unexamined Patent Application Publication No. 2008-24788 JP 2009-263848 A Japanese Unexamined Patent Application Publication No. 2011-162608 Japanese Patent Publication No. 9-509694 JP 2010-186124 A JP 2011-001559 A International publication WO2013/073562 JP 2013-127141 A JP 2013-253200 A International publication WO2014/185505

As described above, fine fibrous cellulose having a phosphate group is known, but when a slurry containing fine fibrous cellulose was prepared using the conditions for introducing a phosphate group in the prior art, the resulting slurry had a viscosity ( The present inventors' studies have revealed that there is a possibility that the solution viscosity) and the fine particle dispersibility may not be sufficient.

Therefore, in order to solve such problems of the prior art, the present inventors have developed a fine fibrous cellulose-containing material having a phosphate group, which can increase the solution viscosity when made into a slurry, and The present inventors have investigated for the purpose of providing a fine fibrous cellulose-containing material capable of improving fine particle dispersibility.

As a result of intensive studies to solve the above problems, the present inventors have found a fine fiber containing fine fibrous cellulose having a phosphoric acid group or a substituent derived from a phosphoric acid group and a group having a urethane bond. It has been found that by setting the content of groups having urethane bonds in the fibrous cellulose-containing material to a predetermined value or more, the viscosity of the solution can be increased and the dispersibility of fine particles can be improved.
Specifically, the present invention has the following configurations.

式（１）中、ａ、ｂ、ｍ及びｎはそれぞれ独立に整数を表す（ただし、ａ＝ｂ×ｍである）；α^ｎ（ｎ＝１～ｎの整数）およびα’はそれぞれ独立にＲ又はＯＲを表す。Ｒは、水素原子、飽和－直鎖状炭化水素基、飽和－分岐鎖状炭化水素基、飽和－環状炭化水素基、不飽和－直鎖状炭化水素基、不飽和－分岐鎖状炭化水素基、芳香族基、又はこれらの誘導基である；βは有機物または無機物からなる１価以上の陽イオンである。
［３］ （Ａ）リン酸基又はリン酸基に由来する置換基の含有量Ｃ_Ａが０．１ｍｍｏｌ／ｇ以上である［１］又は［２］に記載の微細繊維状セルロース含有物。
［４］ 微細繊維状セルロースに導入されたリン酸基に由来する強酸性基と弱酸性基の導入量の差が０．５ｍｍｏｌ／ｇ以下である［１］～［３］のいずれかに記載の微細繊維状セルロース含有物。
［５］ 微細繊維状セルロースの固形分濃度が０．４質量％の溶液であって、微細繊維状セルロースの添加後にディスパーザーにて１５００ｒｐｍ、５分の条件で攪拌して得られる溶液の粘度が５０００ｍＰａ・ｓ以上である［１］～［４］のいずれかに記載の微細繊維状セルロース含有物。
［６］ （Ａ）リン酸基又はリン酸基に由来する置換基の含有量Ｃ_Ａが０．１～２．０ｍｍｏｌ／ｇである［１］～［５］のいずれかに記載の微細繊維状セルロース含有物。
［７］ （Ａ）リン酸基又はリン酸基に由来する置換基の含有量Ｃ_Ａが１．６５～３．８０ｍｍｏｌ／ｇである［１］～［５］のいずれかに記載の微細繊維状セルロース含有物。 [1] A fine fibrous cellulose-containing material containing (A) a phosphoric acid group or a substituent derived from a phosphoric acid group, and (B) a group having a urethane bond, wherein (B) _A fine fibrous cellulose-containing material, wherein the content CB of a group having a urethane bond is 0.05 mmol/g or more per 1 g of fine fibrous cellulose.
[2] (A) A phosphate group or a substituent derived from a phosphate group is a substituent represented by the following formula (1), and (B) a group having a urethane bond is represented by the following formula (2). The fine fibrous cellulose-containing material according to [1], which is a substituent represented by;

In formula (1), a, b, m and n each independently represent an integer (where a=b×m); α ⁿ (n=an integer of 1 to n) and α′ each independently represents R or OR. R is a hydrogen atom, saturated-linear hydrocarbon group, saturated-branched hydrocarbon group, saturated-cyclic hydrocarbon group, unsaturated-linear hydrocarbon group, unsaturated-branched hydrocarbon group , an aromatic group, or a derivative thereof; β is a monovalent or higher cation composed of organic or inorganic substances.
[3] ( _A ) The fine fibrous cellulose-containing material according to [1] or [2], wherein the content CA of the phosphate group or the substituent derived from the phosphate group is 0.1 mmol/g or more.
[4] Any one of [1] to [3], wherein the difference between the introduced amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the fine fibrous cellulose is 0.5 mmol/g or less. of fine fibrous cellulose inclusions.
[5] A solution having a solid content concentration of fine fibrous cellulose of 0.4% by mass, which is obtained by stirring with a disperser at 1500 rpm for 5 minutes after the addition of fine fibrous cellulose has a viscosity of The fine fibrous cellulose-containing material according to any one of [1] to [4], which has a viscosity of 5000 mPa·s or more.
[6] ( _A ) The fine fiber according to any one of [1] to [5], wherein the content CA of a phosphate group or a substituent derived from a phosphate group is 0.1 to 2.0 mmol/g. cellulosic inclusions.
[7] ( _A ) The fine fiber according to any one of [1] to [5], wherein the content CA of a phosphate group or a substituent derived from a phosphate group is 1.65 to 3.80 mmol/g. cellulosic inclusions.

According to the present invention, it is possible to obtain a fine fibrous cellulose-containing material capable of increasing solution viscosity and improving fine particle dispersibility.

FIG. 1 is a graph showing the relationship between the amount of NaOH dripped onto a fiber raw material and electrical conductivity.

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments. In the specification of the present application, a numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits.
In addition, unless otherwise specified, values relating to the mass of fibers such as cellulose are based on absolute dry mass (solid content). "A and/or B" refers to at least one of A and B, unless otherwise specified, and may be A only, B only, or both A and B means that it may be

(Fine fibrous cellulose containing material)
The present invention relates to a fine fibrous cellulose-containing material containing fine fibrous cellulose having (A) a phosphate group or a substituent derived from a phosphate group and (B) a group having a urethane bond. The content CB of ( _B ) groups having urethane bonds in the fine fibrous cellulose is 0.05 mmol/g or more per 1 g (mass) of the fine fibrous cellulose.

Since the fine fibrous cellulose-containing material of the present invention has the above configuration, it is possible to increase the solution viscosity when the fine fibrous cellulose-containing material is made into a slurry, and to improve the dispersibility of fine particles. Thus, the fine fibrous cellulose-containing material of the present invention is preferably used in the field of thickeners and the like.
In addition, the fine fibrous cellulose-containing material of the present invention is excellent in dispersibility when made into a slurry. Therefore, when the fine fibrous cellulose-containing material is slurried, the slurry has high transparency.

The fine fibrous cellulose has (A) a phosphate group or a substituent derived from a phosphate group. A phosphate group is a divalent functional group corresponding to phosphoric acid with the hydroxyl group removed. Specifically, it is a group represented by —PO ₃ H ₂ . Substituents derived from phosphate groups include polycondensation groups of phosphate groups, salts of phosphate groups, phosphate ester groups, and other substituents. may be a base.

The fine fibrous cellulose has (B) a group having a urethane bond. (B) The group having a urethane bond is preferably a group represented by the following structural formula.

In the above structural formula, R is a hydrogen atom, saturated-linear hydrocarbon group, saturated-branched hydrocarbon group, saturated-cyclic hydrocarbon group, unsaturated-linear hydrocarbon group, unsaturated-branched A chain hydrocarbon group, an aromatic group, or a derivative group thereof.

In the specification of the present application, the group having a urethane bond is preferably a group derived from urea, preferably a carbamate group as described later.

In the present invention, (A) a phosphate group or a substituent derived from a phosphate group is preferably a substituent represented by the following formula (1), and (B) a group having a urethane bond is represented by the following formula: It is preferably a substituent represented by (2).

In formula (1), a, b, m and n each independently represent an integer (where a=b×m). α ⁿ (n=an integer from 1 to n) and α′ each independently represent R or OR. R is a hydrogen atom, saturated-linear hydrocarbon group, saturated-branched hydrocarbon group, saturated-cyclic hydrocarbon group, unsaturated-linear hydrocarbon group, unsaturated-branched hydrocarbon group , an aromatic group, or an integer derived from these groups; β is a monovalent or higher cation composed of organic or inorganic substances.

Fine fibrous cellulose includes (A) a phosphate group or a substituent derived from a phosphate group (hereinafter sometimes referred to as a substituent (A)) and (B) a group having a urethane bond (hereinafter, a substituent ( (sometimes referred to as B)). Here, the content CB of the substituent ( _B ) may be 0.05 mmol/g or more, preferably 0.06 mmol/g or more, more preferably 0.10 mmol/g or more. Although the upper limit of the content CB of the substituent ( _B ) is not particularly limited, it can be, for example, 1.0 mmol/g or less. By setting the content CB of the substituent ( _B ) within the above range, the viscosity of the solution when the fine fibrous cellulose-containing material is made into a slurry can be increased, and the dispersibility of fine particles can be improved. .

Also, the content CA of the substituent ( _A ) is preferably 0.10 mmol/g or more. By setting the content CA of the substituent ( _A ) within the above range, the viscosity of the solution when the fine fibrous cellulose-containing material is made into a slurry can be increased, and the dispersibility of fine particles can be improved. . Furthermore, the transparency of the slurry can be enhanced.
As a preferred embodiment, the content C _A of the substituent (A) can be 0.1 to 2.0 mmol/g. As a result, it is possible to obtain a fine fibrous cellulose-containing material excellent in manufacturability while realizing sufficient solution viscosity and fine particle dispersibility. In another preferred embodiment, the content C _A of the substituent (A) can be 1.65 to 3.80 mmol/g. As a result, it is possible to provide a slurry having an even better balance of solution viscosity, fine particle dispersibility, and transparency. The content CA of the substituent ( _A ) can be appropriately adjusted according to its use and purpose.

The ratio of the introduced amount of the substituent (B) to the introduced amount of the substituent (A) is not particularly limited, but is preferably 2% or more, more preferably 3% or more, and 5% or more. is more preferable, and 8% or more is particularly preferable. The upper limit of the ratio of the introduced amount of the substituent (B) to the introduced amount of the substituent (A) is preferably 25%. The ratio of the amount of the substituent (B) introduced to the amount of the substituent (A) introduced is the content of the substituent (B) (mmol/g)/the content of the substituent (A) (mmol/g)×100. can be calculated by By setting the ratio of the introduction amount of the substituent (B) to the introduction amount of the substituent (A) within the above range, the viscosity of the solution when the fine fibrous cellulose-containing material is made into a slurry can be increased, and Fine particle dispersibility can be improved.

The introduction amount of the substituent (A) can be measured by a conductivity titration method. Specifically, after miniaturization is performed in a fibrillation treatment step, the obtained fine fibrous cellulose-containing slurry is treated with an ion exchange resin, and then a change in electrical conductivity is determined while adding an aqueous sodium hydroxide solution. The amount introduced can be measured.
In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) was added to a slurry containing 0.2% by mass of fine fibrous cellulose, and the mixture was shaken for 1 hour. process. After that, it is poured onto a mesh with an opening of 90 μm to separate the resin from the slurry. In the titration using an alkali, the change in the electrical conductivity value of the slurry is measured while adding a 0.1N sodium hydroxide aqueous solution to the ion-exchanged fine fibrous cellulose-containing slurry.

Conductometric titration gives the curve shown in FIG. 1 as alkali is added. At first, the electrical conductivity drops abruptly (hereinafter referred to as "first region"). After that, the conductivity starts to rise slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). That is, three regions appear. Of these, the amount of alkali required in the first region is equal to the amount of strong acid groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weak acid groups in the slurry used for titration. be equal. When the phosphate groups condense, the weakly acidic groups are apparently lost, and the amount of alkali required for the second region becomes smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation, so it can be simply referred to as the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituents introduced (or the amount of substituents). When said, it represents the amount of strongly acidic groups.
That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 is divided by the solid content (g) in the slurry to be titrated to obtain the substituent introduction amount (mmol/g).

The introduction amount of the substituent (B) is determined by measuring the amount of nitrogen covalently bonded to cellulose. That is, after liberating ionic nitrogen (ammonium ion), it is measured by trace nitrogen analysis. Liberation of ionic nitrogen (ammonium ion) is carried out under conditions in which substantially no nitrogen covalently bound to cellulose is removed. Examples include a method of treating cellulose with an acid or alkali before the micronization step, and a method of treating the cellulose with a strongly acidic ion-exchange resin or the like after the micronization step.
For trace nitrogen analysis, for example, it can be measured by using a trace total nitrogen analyzer TN-110 manufactured by Mitsubishi Chemical Analytic. Prior to measurement, dry at a low temperature and remove the solvent before testing. The introduction amount (mmol/g) of the substituent (B) per unit mass of fine fibrous cellulose is obtained by dividing the nitrogen content (g/g) per unit mass of fine fibrous cellulose obtained by trace nitrogen analysis into the atomic weight of nitrogen. It is obtained by dividing by

The content of the substituent (A) and the content of the substituent (B) are the amounts of a compound having a phosphate group and/or a salt thereof and urea and/or a derivative thereof added in the step of introducing a phosphate group described later. can be adjusted by controlling In particular, it is presumed that adjusting the amount of urea and/or its derivative to be added relative to the amount of phosphorus atom added is important as it can affect the content of the substituent (B). Moreover, the content of the substituent (A) and the content of the substituent (B) can also be adjusted by controlling the heating temperature and the like in the phosphate group introduction step. The present invention has been realized for the first time based on such new findings by the inventors.

The fine fibrous cellulose-containing material of the present invention is characterized by its high solution viscosity when dispersed in water to form a slurry. Specifically, when a slurry containing fine fibrous cellulose was prepared so that the solid content concentration of fine fibrous cellulose was 0.4% by mass, the disperser was run at 1500 rpm after the addition of fine fibrous cellulose. The viscosity of the solution (slurry) obtained by stirring for 5 minutes is preferably 5000 mPa·s or more. The viscosity of the solution (slurry) is more preferably 8000 mPa s or more, still more preferably 10000 mPa s or more, even more preferably 12000 mPa s or more, even more preferably 14000 mPa s or more. Especially preferred. The viscosity of the solution (slurry) is measured using a Brookfield viscometer (manufactured by BLOOKFIELD, analog viscometer T-LVT) under the conditions of 3 rpm and 25°C. .

The fine fibrous cellulose-containing material of the present invention may be a liquid such as a slurry, a solid such as a powder, or a gel.

When the fine fibrous cellulose-containing material is a liquid, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing material is 0.1 to 5.0 with respect to the total mass of the fine fibrous cellulose-containing material. % by mass is preferable, 0.3 to 3.0% by mass is more preferable, and 0.5 to 3.0% by mass is even more preferable. By setting the content of the fine fibrous cellulose within the above range, the properties of the fine fibrous cellulose are easily exhibited.

When the fine fibrous cellulose containing material is a particulate material containing fine fibrous cellulose, the fine fibrous cellulose containing material consists of a powdery and/or granular material. Here, powdery substances refer to substances smaller than granular substances. In general, powdery substances refer to fine particles having a particle size of 1 nm or more and less than 0.1 mm, and granular substances refer to particles having a particle size of 0.1 to 10 mm, but are not particularly limited. The particle size of the powder can be measured and calculated using a laser diffraction method. Specifically, it is a value measured using a laser diffraction/scattering particle size distribution analyzer (Microtrac 3300EXII, Nikkiso Co., Ltd.).

When the fine fibrous cellulose-containing material is fine fibrous cellulose-containing granules, a known manufacturing method can be employed as the manufacturing method thereof. For example, an oven dry method or a spray dry method can be adopted.

When the fine fibrous cellulose-containing material is a solid or gel-like material, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing material is 5 masses with respect to the total mass of the fine fibrous cellulose-containing material. %, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. Further, when the fine fibrous cellulose-containing material is a solid or gel-like material, the upper limit of the content of fine fibrous cellulose contained in the fine fibrous cellulose-containing material is not particularly limited, but for example 99.5 % by mass. By setting the content of the fine fibrous cellulose within the above range, it is possible to obtain a fine fibrous cellulose-containing material that is more excellent in handleability.

<Other ingredients>
The fine fibrous cellulose containing material may contain other components in addition to the fine fibrous cellulose. Other components include water-soluble polymers and surfactants. Examples of water-soluble polymers include synthetic water-soluble polymers (e.g., carboxyvinyl polymer, polyvinyl alcohol, alkyl methacrylate/acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, polyethylene glycol, diethylene glycol, triethylene glycol, polyethylene oxide, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide, etc.), thickening polysaccharides (e.g., xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince) seeds, alginic acid, pullulan, carrageenan, pectin, etc.), cellulose derivatives (e.g., carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, etc.), cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, amylose, etc. Examples include starches, glycerins such as glycerin, diglycerin, and polyglycerin, hyaluronic acid, metal salts of hyaluronic acid, and the like. Moreover, as surfactant, a nonionic surfactant, an anionic surfactant, and a cationic surfactant can be used.

(fine fibrous cellulose)
Although the fibrous cellulose raw material for obtaining fine fibrous cellulose is not particularly limited, it is preferable to use pulp because it is readily available and inexpensive. Pulp includes wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen-bleached kraft. chemical pulp such as pulp (OKP); Semi-chemical pulp (SCP), semi-chemical pulp such as chemi-groundwood pulp (CGP), mechanical pulp such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP), etc., but not particularly limited. . Examples of non-wood pulp include, but are not limited to, cotton pulp such as cotton linters and cotton lint, non-wood pulp such as hemp, straw, and bagasse, and cellulose, chitin, and chitosan isolated from sea squirts, seaweed, and the like. . The deinked pulp includes deinked pulp made from waste paper, but is not particularly limited. The pulp of this embodiment may be used alone or in combination of two or more. Among the above pulps, cellulose-containing wood pulp and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a high cellulose ratio, so the yield of fine fibrous cellulose at the time of fiber refinement (fibrillation) is high. It is preferable in that fibrous cellulose can be obtained. Among them, kraft pulp and sulfite pulp are most preferably selected. Sheets containing fine fibrous cellulose with long fibers having a large axial ratio tend to provide high strength.

The average fiber width of fine fibrous cellulose is 1000 nm or less when observed with an electron microscope. The average fiber width is preferably 2 to 1000 nm, more preferably 2 to 100 nm, more preferably 2 to 50 nm, still more preferably 2 to 10 nm, but is not particularly limited. If the average fiber width of the fine fibrous cellulose is less than 2 nm, the physical properties (strength, rigidity, dimensional stability) of the fine fibrous cellulose tend to be difficult to develop because the cellulose molecules are dissolved in water. . The fine fibrous cellulose is, for example, monofibrous cellulose having a fiber width of 1000 nm or less.

The measurement of the fiber width of fine fibrous cellulose by electron microscopic observation is carried out as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05 to 0.1% by mass is prepared, and this suspension is cast on a hydrophilized carbon film-coated grid to obtain a sample for TEM observation. SEM images of surfaces cast on glass may be observed if they contain wide fibers. Observation with an electron microscope image is performed at a magnification of 1,000, 5,000, 10,000, or 50,000 times depending on the width of the constituent fibers. However, the sample, observation conditions and magnification are adjusted so as to satisfy the following conditions.

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

The width of the fiber crossing the straight line X and the straight line Y is visually read from the observed image satisfying the above conditions. Three or more sets of images of at least non-overlapping surface portions are observed, and the width of the fiber intersecting the straight lines X and Y is read for each image. At least 20 x 2 x 3 = 120 fiber widths are thus read. The average fiber width of fine fibrous cellulose (sometimes simply referred to as "fiber width") is the average value of the fiber widths thus read.

Although the fiber length of fine fibrous cellulose is not particularly limited, it is preferably 0.1 to 1000 μm, more preferably 0.1 to 800 μm, and particularly preferably 0.1 to 600 μm. By setting the fiber length within the above range, destruction of the crystalline regions of the fine fibrous cellulose can be suppressed, and the slurry viscosity of the fine fibrous cellulose can be set within an appropriate range. The fiber length of fine fibrous cellulose can be determined by image analysis using TEM, SEM, and AFM.

Preferably, the fine fibrous cellulose has a Type I crystal structure. Here, the fact that the fine fibrous cellulose has a type I crystal structure can be identified in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ=1.5418 Å) monochromated with graphite. Specifically, it can be identified by having typical peaks at two positions near 2θ=14 to 17° and near 2θ=22 to 23°.
The proportion of the I-type crystal structure in the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, still more preferably 70% or more.

Although the ratio of the crystalline portion contained in the fine fibrous cellulose is not particularly limited in the present invention, it is preferable to use cellulose with a degree of crystallinity of 60% or more as determined by X-ray diffraction. The degree of crystallinity is preferably 65% or more, more preferably 70% or more. In this case, even better performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion. The degree of crystallinity is determined by a conventional method from the pattern of X-ray diffraction profiles (Seagal et al., Textile Research Journal, vol. 29, p. 786, 1959).

<Phosphorylation treatment>
In the present invention, the fine fibrous cellulose has (A) a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group) and (B) a group having a urethane bond. . (A) a phosphoric acid group or a substituent derived from a phosphoric acid group, and (B) a group having a urethane bond are introduced through a phosphoric acid group-introducing step described below.

<Phosphate group introduction step>
The phosphate group-introducing step can be performed by reacting a fiber raw material containing cellulose with a compound having a phosphate group and/or a salt thereof (hereinafter referred to as "compound A"). This reaction is carried out in the presence of urea and/or its derivative (hereinafter referred to as "compound B"). Thereby, (A) a phosphoric acid group or a substituent derived from a phosphoric acid group and (B) a group having a urethane bond can be introduced into the hydroxyl group of the fine fibrous cellulose. In the present invention, such a method for introducing a phosphate group may be referred to as a urea phosphorylation method.

The phosphate group-introducing step necessarily includes the step of introducing the substituent (A) and the substituent (B) into the cellulose as described above, and optionally includes an alkali treatment step, a step of washing excess reagent, and the like, which will be described later. may be included.

An example of the method of allowing the compound A to act on the fiber raw material in the presence of the compound B includes a method of mixing the powder or aqueous solution of the compound A and the compound B with the fiber raw material in a dry or wet state. Another example is a method of adding powder or an aqueous solution of compound A and compound B to a slurry of fiber raw materials. Among these, the method of adding an aqueous solution of the compound A and the compound B to the fiber raw material in a dry state, or the method of adding a powder or an aqueous solution of the compound A and the compound B to the fiber raw material in a wet state, because the uniformity of the reaction is high. A method is preferred. Compound A and compound B may be added simultaneously or separately. Alternatively, compound A and compound B to be tested in the reaction may be first added as an aqueous solution, and excess chemical solution may be removed by squeezing. The form of the fiber raw material is preferably cotton-like or thin sheet-like, but is not particularly limited.

Compound A used in this embodiment is a compound having a phosphate group and/or a salt thereof.
Examples of the compound having a phosphate group include, but are not limited to, phosphoric acid, lithium phosphoric acid, sodium phosphoric acid, potassium phosphoric acid, and ammonium phosphoric acid. Lithium salts of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, lithium polyphosphate, and the like. Sodium salts of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium polyphosphate, and the like. Potassium salts of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate. Ammonium salts of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.

Among these, the efficiency of introduction of the substituent (A) is high, the fibrillation efficiency is easily improved in the fibrillation step described later, the cost is low, and it is easy to apply industrially. Sodium salts of acids, potassium phosphates, and ammonium phosphates are preferred. More preferred is sodium dihydrogen phosphate or disodium hydrogen phosphate.

In addition, it is preferable to use the compound A as an aqueous solution because the uniformity of the reaction is enhanced and the efficiency of introduction of the phosphate group is enhanced. Although the pH of the aqueous solution of compound A is not particularly limited, it is preferably 7 or less because the efficiency of introduction of the substituent (A) is increased, and from the viewpoint of suppressing hydrolysis of pulp fibers, pH 3 to 7 is more preferable. The pH of the aqueous solution of compound A may be adjusted by, for example, using both acidic and alkaline compounds among the compounds having a phosphate group and changing the amount ratio. The pH of the aqueous solution of compound A may be adjusted by adding an inorganic alkali or an organic alkali to an acidic compound having a phosphoric acid group.

The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to the amount of phosphorus atoms, the amount of phosphorus atoms added to the fiber raw material (absolute dry mass) is preferably 0.5 to 100% by mass. , more preferably 1 to 50% by mass, most preferably 2 to 30% by mass. If the amount of phosphorus atoms added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. If the amount of phosphorus atoms added to the fiber raw material exceeds 100% by mass, the effect of improving the yield reaches a plateau and the cost of the compound A used increases. On the other hand, the yield can be increased by setting the amount of phosphorus atoms added to the fiber raw material to be equal to or higher than the above lower limit.

Compound B used in this embodiment includes urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like. Among these, urea is preferable because it is low cost, easy to handle, and the efficiency of introduction of the substituent (B) is high.

As with compound A, compound B is preferably used as an aqueous solution. Moreover, it is preferable to use an aqueous solution in which both the compound A and the compound B are dissolved because the uniformity of the reaction is enhanced. The amount of compound B added to the fiber raw material (absolute dry mass) is preferably 1 to 500% by mass, more preferably 10 to 400% by mass, further preferably 100 to 350% by mass, and 150% by mass. It is particularly preferred to be up to 300% by mass.

In addition to compound A and compound B, amides or amines may be included in the reaction system. Amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine in particular is known to work as a good reaction catalyst.

Heat treatment is preferably performed in the step of introducing a phosphate group. As for the heat treatment temperature, it is preferable to select a temperature at which the substituent (A) and the substituent (B) can be efficiently introduced while suppressing thermal decomposition and hydrolysis reaction of the fiber. Specifically, the temperature is preferably 50 to 300°C, more preferably 100 to 250°C, even more preferably 150 to 200°C. For heating, a vacuum dryer, an infrared heating device, or a microwave heating device may be used.

During the heat treatment, when the fiber raw material slurry to which the compound A is added contains water, if the fiber raw material is allowed to stand for a longer period of time, the water molecules and the dissolved compound A move to the surface of the fiber raw material as it dries. do. Therefore, there is a possibility that the concentration of the compound A in the fiber raw material may be uneven, and the introduction of the phosphate group to the fiber surface may not proceed uniformly. In order to suppress the concentration unevenness of the compound A in the fiber raw material due to drying, a very thin sheet-like fiber raw material is used, or the fiber raw material and the compound A are kneaded with a kneader or the like and/or heated and dried while stirring or under reduced pressure. A drying method should be adopted.

The heating device used for the heat treatment is preferably a device capable of constantly discharging the moisture retained by the slurry and the moisture generated by the addition reaction of the hydroxyl groups of fibers such as phosphoric acid groups to the outside of the device system. etc. are preferred. If the water in the system is constantly discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of phosphorylation, can be suppressed, and the acid hydrolysis of the sugar chains in the fiber can also be suppressed. , fine fibers with a high axial ratio can be obtained.

The heat treatment time is preferably 1 second to 300 minutes, more preferably 1 second to 1000 seconds, after water is substantially removed from the fiber raw material slurry, although it is also affected by the heating temperature. More preferably, it is 10 seconds to 800 seconds. In the present invention, the amounts of the substituent (A) and the substituent (B) to be introduced can be set within a preferable range by setting the heating temperature and the heating time within appropriate ranges.

The ratio A _B /A _P of the phosphorus atom addition amount A _P to the fiber raw material and the addition amount A _B of the compound B to the fiber raw material is, for example, preferably 7.0 or more, and is 10.0 or more. is more preferable, and 15.0 or more is particularly preferable. On the other hand, the upper limit of _AB / _AP is not particularly limited, and can be set to 100, for example. This makes it easier to bring the contents of the substituent (A) and the substituent (B) into the desired ranges.

In addition, in the present invention, the difference between the introduction amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the fine fibrous cellulose is preferably 0.5 mmol/g or less, more preferably 0.3 mmol/g. It is more preferably 0.2 mmol/g or less, more preferably 0.2 mmol/g or less. That is, in the phosphate group-introducing step, the reaction is preferably carried out so that the difference between the introduced amounts of the strongly acidic groups and the weakly acidic groups derived from the phosphate groups introduced into the fine fibrous cellulose is 0.5 mmol/g or less. , is more preferably 0.3 mmol/g or less, and particularly preferably 0.2 mmol/g or less. A highly transparent fine fibrous cellulose can be obtained by setting the difference between the introduced amounts of the strongly acidic group and the weakly acidic group within the above range.

The step of introducing a phosphate group may be performed at least once, but may be repeated multiple times. In this case, more substituents (A) and (B) are introduced, which is preferable.

As described above, the production process of the fine fibrous cellulose-containing material of the present invention includes a phosphate group introduction step, and the phosphate group introduction step is performed in the presence of urea and / or a derivative thereof, a compound having a phosphate group and/or a step of reacting a salt thereof.
In the phosphate group introduction step, the amount of the compound having a phosphate group and/or its salt added to the fiber raw material of urea and/or its derivative is 0.5 to 100% by mass, and the addition of urea and/or its derivative The amount is preferably 1-500% by weight.
Moreover, it is preferable that the step of introducing a phosphate group includes a heating step. The heating temperature and heating time in the heating step are preferably within the ranges described above.

<Alkaline treatment>
When producing fine fibrous cellulose, alkali treatment can be performed between the step of introducing phosphate groups and the later-described fibrillation treatment step. The alkali treatment method is not particularly limited, but an example thereof includes a method of immersing the phosphate group-introduced fiber in an alkali 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. Either water or an organic solvent may be used as the solvent in the alkaline solution. The solvent is preferably a polar solvent (water or a polar organic solvent such as alcohol), more preferably an aqueous solvent containing at least water.
Among alkaline solutions, sodium hydroxide aqueous solution or potassium hydroxide aqueous solution is particularly preferable because of its high versatility.

Although the temperature of the alkaline solution in the alkaline treatment step is not particularly limited, it is preferably 5 to 80°C, more preferably 10 to 60°C.
The immersion time in the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 to 30 minutes, more preferably 10 to 20 minutes.
The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but it is preferably 100 to 100,000% by mass, more preferably 1,000 to 10,000% by mass, relative to the absolute dry mass of the phosphate group-introduced fiber.

In order to reduce the amount of alkaline solution used in the alkali treatment step, the phosphate group-introduced fiber may be washed with water or an organic solvent before the alkali treatment step. After the alkali treatment, it is preferable to wash the alkali-treated phosphate group-introduced fiber with water or an organic solvent before the defibration treatment step in order to improve handleability.

<Fibrillation treatment>
The fibers into which the substituent (A) and the substituent (B) have been introduced are defibrated in the fibrillation treatment step. In the defibration treatment step, fibers are usually defibrated using a fibrillation treatment apparatus to obtain fine fibrous cellulose-containing slurry, but the treatment apparatus and treatment method are not particularly limited.
A high-speed defibrator, a grinder (stone mill-type pulverizer), a high-pressure homogenizer, an ultra-high-pressure homogenizer, a high-pressure collision-type pulverizer, a ball mill, a bead mill, or the like can be used as the defibration processing device. Alternatively, as a fibrillation processing device, use a device for wet pulverization such as a disk-type refiner, conical refiner, twin-screw kneader, vibration mill, homomixer under high-speed rotation, ultrasonic disperser, or beater. can also The defibration processing device is not limited to the above. Preferable defibration treatment methods include a high-speed fibrillation machine, a high-pressure homogenizer, and an ultrahigh-pressure homogenizer, which are less affected by the grinding media and less likely to cause contamination.

In the defibration treatment, it is preferable to dilute the fiber raw material with water and an organic solvent alone or in combination to form a slurry, but there is no particular limitation. As a dispersion medium, a polar organic solvent can be used in addition to water. Preferred polar organic solvents include, but are not limited to, alcohols, ketones, ethers, dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like. Alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol, and the like. Ketones include acetone, methyl ethyl ketone (MEK), and the like. Ethers include diethyl ether, tetrahydrofuran (THF), and the like. One type of dispersion medium may be used, or two or more types may be used. Further, the dispersion medium may contain a solid content other than the fiber raw material, such as urea having hydrogen bonding properties.

In the present invention, defibration treatment may be performed after concentrating and drying the fine fibrous cellulose. In this case, the method of concentration and drying is not particularly limited, but examples thereof include a method of adding a thickening agent to a slurry containing fine fibrous cellulose, a method of using a commonly used dehydrator, a press, and a dryer. Also, known methods such as those described in WO2014/024876, WO2012/107642, and WO2013/121086 can be used. Alternatively, the concentrated fine fibrous cellulose may be formed into a sheet. The sheet can also be pulverized and defibrated.

Equipment used for pulverizing fine fibrous cellulose includes high-speed fibrillators, grinders (stone mill type pulverizers), high pressure homogenizers, ultra-high pressure homogenizers, high pressure impact type pulverizers, ball mills, bead mills, disk refiners, and conicals. A wet pulverizing device such as a refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, a beater, etc. may be used, but is not particularly limited.

The fine fibrous cellulose-containing substance having the substituent (A) and the substituent (B) obtained by the method described above is a fine fibrous cellulose-containing slurry, which is diluted with water to a desired concentration. may be used. That is, the fine fibrous cellulose-containing material of the present invention may be a fine fibrous cellulose-containing slurry. In this case, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing slurry is preferably 0.1 to 5.0% by mass with respect to the total mass of the fine fibrous cellulose-containing material. It is more preferably 3 to 3.0% by mass, even more preferably 0.5 to 3.0% by mass.

(Application)
The use of the fine fibrous cellulose-containing material according to the present invention is not particularly limited. For example, it can be used as a thickening agent in various applications (eg, additives for foods, cosmetics, cement, paints, inks, etc.). In this case, the object to be added may contain fine particles and the like, and in such a case, the fine fibrous cellulose containing material can uniformly disperse the fine particles.
When the fine fibrous cellulose-containing material is used as a thickening agent, it is also preferable to concentrate the fine fibrous cellulose-containing material. Examples of such a form include forms such as a concentrated liquid and a granular material.

As another example of the application of the material containing fine fibrous cellulose, a slurry containing fine fibrous cellulose can be used to form a sheet, which can be used as various films. When producing a sheet containing fine fibrous cellulose, it is preferable to include the step of coating the slurry containing fine fibrous cellulose on a substrate or the step of making paper from the slurry containing fine fibrous cellulose. Further, the fine fibrous cellulose-containing material of the present invention may be mixed with a matrix resin or the like to form a composite sheet containing fine fibrous cellulose.

Furthermore, the fine fibrous cellulose inclusions can be mixed with resins or emulsions and used as reinforcing materials.

EXAMPLES The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

(Production example 1)
As the softwood kraft pulp, pulp manufactured by Oji Paper Co., Ltd. (solid content 93%, basis weight 208 g / m ² sheet, defibered and Canadian standard freeness (CSF) 700 ml measured according to JIS P 8121) was used. . 100 parts by mass of the softwood kraft pulp (absolute dry mass) is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, pressed to 45 parts by mass of ammonium dihydrogen phosphate and 200 parts by mass of urea, and impregnated with a chemical solution. A pulp was obtained. The resulting chemical solution-impregnated pulp was dried and heat-treated for 200 seconds in a hot air dryer at 165° C. to introduce substituents into cellulose in the pulp.

Pour 10,000 parts by mass of ion-exchanged water into 100 parts by mass of the obtained phosphorylated pulp (absolute dry mass), stir to uniformly disperse, filter and dehydrate, and obtain a dehydrated sheet twice. repeated. Next, the obtained dehydrated sheet was diluted with 10,000 parts by mass of ion-exchanged water, and a 1N sodium hydroxide aqueous solution was added little by little while stirring to obtain a pulp slurry having a pH of 12-13. Thereafter, the pulp slurry is dewatered to obtain a dehydrated sheet, and then 10,000 parts by mass of ion-exchanged water is poured into the pulp slurry, stirred to uniformly disperse, filtered and dehydrated, and the process of obtaining a dehydrated sheet is repeated twice. to obtain a dehydrated sheet of phosphorylated pulp.

(Production example 2)
In the same manner as in Production Example 1, except that the dehydrated sheet of phosphorylated pulp obtained in Production Example 1 was used as a raw material, the step of introducing a phosphoric acid group was repeated once more (the total number of phosphorylation times was 2). , to obtain dehydrated sheets of phosphorylated pulp.

(Production example 3)
In the same manner as in Production Example 2, except that the dehydrated sheet of phosphorylated pulp obtained in Production Example 2 was used as a raw material, the step of introducing a phosphoric acid group was repeated once more (the total number of phosphorylation times was 3). , to obtain dehydrated sheets of phosphorylated pulp.

(Production example 4)
A dehydrated sheet of phosphorylated pulp was obtained in the same manner as in Production Example 1, except that the treatment time in a hot air dryer heated to 165° C. was changed to 150 seconds.

(Production example 5)
100 parts by mass of coniferous kraft pulp (absolute dry mass) is impregnated with a mixed aqueous solution of sodium dihydrogen phosphate and urea, and pressed to 58 parts by mass of sodium dihydrogen phosphate and 100 parts by mass of urea. After that, a dehydrated sheet of phosphorylated pulp was obtained in the same manner as in Production Example 1 except that the temperature of the hot air dryer was 140° C. and the heating time was 900 seconds.

(Example 1)
After ion-exchanged water was added to the dehydrated sheet of phosphorylated pulp obtained in Production Example 1, the mixture was stirred to obtain a slurry having a solid content concentration of 0.5% by mass. This slurry was defibrated for 30 minutes at 21,500 rpm using a fibrillation treatment apparatus (Clearmix-2.2S, manufactured by M Technic Co., Ltd.) to obtain a fine fibrous cellulose-containing slurry. The viscosity and fine particle dispersion stability of this fine fibrous cellulose-containing slurry were measured by the following methods. In addition, the introduction amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the cellulose and the content of the substituent (B) were determined.

(Examples 2-4)
A fine fibrous cellulose-containing slurry was prepared in the same manner as in Example 1, except that the dehydrated sheets of phosphorylated pulp obtained in Production Examples 2 to 4 were used. The viscosity and fine particle dispersion stability of each fine fibrous cellulose-containing slurry were measured by the following methods. In addition, the introduction amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the cellulose and the content of the substituent (B) were determined.

(Comparative example 1)
A fine fibrous cellulose-containing slurry was prepared in the same manner as in Example 1, except that the dehydrated sheet of phosphorylated pulp obtained in Production Example 5 was used. The viscosity of the fine fibrous cellulose-containing slurry and the fine particle dispersion stability were measured by the following methods. In addition, the introduction amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the cellulose and the content of the substituent (B) were determined.

<Measurement of introduction amount of substituent (A)>
The introduction amount of the substituent (A) was measured by a conductivity titration method. Specifically, after miniaturization is performed in a fibrillation treatment step, the obtained fine fibrous cellulose-containing slurry is treated with an ion exchange resin, and then a change in electrical conductivity is determined while adding an aqueous sodium hydroxide solution. The amount introduced was measured.
In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) was added to a slurry containing 0.2% by mass of fine fibrous cellulose, and the mixture was shaken for 1 hour. processed. After that, the slurry was separated from the resin by pouring it onto a mesh with an opening of 90 μm. In the titration with alkali, the change in the electrical conductivity value of the slurry was measured while adding 0.1N sodium hydroxide aqueous solution to the ion-exchanged fine fibrous cellulose-containing slurry.
Then, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 was divided by the solid content (g) in the slurry to be titrated to obtain the substituent introduction amount (mmol/g).

<Measurement of introduction amount of substituent (B) (trace nitrogen analysis method)>
The introduction amount of the substituent (B) was determined by measuring the amount of nitrogen covalently bonded to cellulose. Specifically, after liberating and removing ionic nitrogen (ammonium ion), the amount of nitrogen was measured by trace nitrogen analysis. Liberation of ionic nitrogen (ammonium ion) was carried out under conditions in which substantially no nitrogen covalently bound to cellulose was removed. Removal of liberated ammonium ions was carried out in the same manner as the measurement of the introduced amount of the substituent (A). That is, ammonium ions were adsorbed on a strongly acidic ion exchange resin.
Trace nitrogen analysis was performed using a total trace nitrogen analyzer TN-110 manufactured by Mitsubishi Chemical Analytic. Before the measurement, it was dried at a low temperature (40°C for 24 hours in a vacuum dryer) to remove the solvent.
The introduction amount (mmol/g) of the substituent (B) per unit mass of fine fibrous cellulose is obtained by dividing the nitrogen content (g/g) per unit mass of fine fibrous cellulose obtained by trace nitrogen analysis into the atomic weight of nitrogen. obtained by dividing by

<Method for measuring viscosity of fine fibrous cellulose-containing slurry>
After diluting the viscosity of the fine fibrous cellulose-containing slurry so that the solid content concentration of the fine fibrous cellulose-containing slurry was 0.4% by mass, the slurry was stirred at 1500 rpm for 5 minutes with a disperser. The viscosity of the resulting slurry was measured using a Brookfield viscometer (manufactured by BLOOKFIELD, analog viscometer T-LVT). The measurement conditions were 3 rpm and 25°C.

<Evaluation of fine particle dispersion stability>
After adding hydrophobized titanium oxide (STV-455, manufactured by Titan Kogyo Co., Ltd.) to 0.5% by mass of fine fibrous cellulose-containing slurry obtained in Examples and Comparative Examples so that it becomes 1.0% by mass. , using a homomixer at a rotation speed of 4,000 rpm for 5 minutes. Then, it was left to stand for 30 minutes, and it was observed whether the hydrophobized titanium oxide separated from the water layer. Evaluation was performed according to the following criteria.
◯: Hydrophobized titanium oxide was not separated at all, maintaining uniformity.
Δ: Some hydrophobized titanium oxide separated and precipitated or existed on the water surface was observed, but overall uniformity was maintained.
x: As a whole, hydrophobized titanium oxide particles were precipitated or existed on the surface of the water, and separated from the water layer.

The slurries containing fine fibrous cellulose obtained in Examples had high solution viscosities and good fine particle dispersion stability.

Claims (4)

(A) a phosphate group or a substituent derived from a phosphate group, and (B) a fine fibrous cellulose containing group having a urethane bond,
The (A) phosphate group or a substituent derived from a phosphate group is a substituent represented by the following formula (1),
The (B) group having a urethane bond is a substituent represented by the following formula (2),
( _A ) the content CA of the phosphate group or the substituent derived from the phosphate group is 0.57 mmol/g or more,
The value calculated by (B) the content of the group having a urethane bond (mmol/g)/the content of the (A) phosphoric acid group or a substituent derived from a phosphoric acid group (mmol/g)×100 is , a fine fibrous cellulose content of 8 % or more;

In formula (1), a, b, m and n each independently represent an integer (where a=b×m); α ⁿ (n=an integer of 1 to n) and α′ each independently represents R or OR. R is a hydrogen atom, saturated-linear hydrocarbon group, saturated-branched hydrocarbon group, saturated-cyclic hydrocarbon group, unsaturated-linear hydrocarbon group, unsaturated-branched hydrocarbon group or an aromatic group; β is a monovalent or higher cation of organic or inorganic matter. 2. The fine fibrous cellulose-containing material according to claim 1 , wherein the content CB of ( _B ) a group having a urethane bond is 1.0 mmol/g or less. 3. The material containing fine fibrous cellulose according to claim 1 or 2 , wherein the difference between the introduced amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced into the fine fibrous cellulose is 0.5 mmol/g or less. . A solution having a solid content concentration of the fine fibrous cellulose of 0.4% by mass, which is obtained by stirring with a disperser at 1500 rpm for 5 minutes after the addition of the fine fibrous cellulose, has a viscosity of 5000 mPa. · The fine fibrous cellulose-containing material according to any one of claims 1 to 3 , wherein the content is s or more.

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