JP7828140B2 - Granulating agent for powder, granulated product using the same, and method for producing the same - Google Patents

Description

The present invention relates to a granulating agent for powders, a granulated product using the same, and a method for producing the same.

Water-soluble polymers are widely used as binders when granulating various powders and as binding agents when formulating pharmaceuticals.
Patent Document 1 describes a granulating agent for powdered metal raw materials, which is characterized by containing one or more binder components selected from carboxymethylcellulose salts, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, polyvinyl alcohol, polyacrylamide, polyacrylates, guar gum, tamarind gum, and starch, with the aim of providing a granulating agent for powdered metal raw materials and a wet granulation method for powdered metal raw materials using the same, which can be applied not only to the steel manufacturing industry but also to the metal material manufacturing industry in general.

Patent Document 2 describes a method for granulating sinter raw materials, such as iron ore, to obtain granulated particles with excellent pseudo-particle forming properties, which are effective in improving air permeability and productivity in sintering machines. The method involves blending quicklime with the sinter raw materials, such as iron ore, and performing primary granulation by sprinkling water. Then, a liquid binder with a viscosity of 5 to 100 mPa·s is added to perform secondary granulation, resulting in granulated material with a moisture content of 6 to 9% by mass. It also describes that the liquid binder preferably contains one or more selected from the group consisting of bentonite, guar gum, polyvinyl alcohol, polyacrylamide, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl ethyl cellulose, starch, lignin, and water glass.

Patent Document 3 describes a stabilized solid formulation of (R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, and describes how the use of sugar alcohols and starches as excipients results in a solid formulation with excellent stability.

Japanese Patent Application Laid-Open No. 2000-178662 Japanese Patent Application Laid-Open No. 2007-113086 WO 00/10557

Patent Documents 1 and 2 describe a technique for granulating dust or iron ore from steel mills using a solution of a water-soluble polymer as a binder, but the strength of the granules obtained is insufficient.
Furthermore, Patent Document 3 discloses a technique for formulating pharmaceuticals using water-soluble polymers as excipients, but does not consider the strength of the formulation.

The present invention aims to provide a granulating agent for powders that has low viscosity, can be mixed uniformly with powders, and produces granulated products with high particle hardness, as well as a granulated product using the powder granulating agent and a method for producing the same.

The inventors discovered that a powder granulating agent containing fibrous cellulose containing fine fibrous cellulose and a water-soluble polymer is effective as a binder when granulating powder, leading to the completion of the present invention.

That is, the present invention relates to the following items <1> to <14>.
<1> A granulated product obtained by granulating at least one powder selected from the group consisting of inorganic powders and organic powders with fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less and a binder component containing a water-soluble polymer.
<2> The granules according to <1>, wherein the fibrous cellulose contains pulp fibers having a fiber width of more than 1,000 nm.
<3> The granule according to <1> or <2>, wherein the content of the fine fibrous cellulose in the fibrous cellulose is 5% by mass or more and 100% by mass or less.
<4> The granule according to any one of <1> to <3>, wherein the fine fibrous cellulose has an anionic group.
<5> The granule according to any one of <1> to <4>, wherein the total solid content of the fibrous cellulose and the water-soluble polymer is 0.001 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the powder.
<6> The granule according to any one of <1> to <5>, wherein the blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) is 1/10 or more and 1000/1 or less.
<7> The granulated product according to any one of <1> to <6>, wherein the water-soluble polymer contains a high-viscosity water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23°C, and a low-viscosity water-soluble polymer having a viscosity of 100 mPa·s or less in a 1% by mass aqueous solution at 23°C.
<8> The granulated product according to <7>, wherein the blending ratio of the high-viscosity water-soluble polymer to the low-viscosity water-soluble polymer (high-viscosity water-soluble polymer/low-viscosity water-soluble polymer, mass ratio) is 1/1 or more and 20/1 or less.
<9> The granule according to <7> or <8>, wherein the high-viscosity water-soluble polymer is selected from the group consisting of carboxymethyl cellulose, oxidized starch, polyacrylamide, guar gum, and polyacrylic acid.
<10> The granulated product according to any one of <7> to <9>, wherein the low-viscosity water-soluble polymer is selected from the group consisting of polyacrylates and alginates.
<11> The granulated product according to any one of <1> to <10>, wherein the particle size of the powder is 12 mesh or more.
<12> A granulating agent for powder, comprising fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less, and a water-soluble polymer.
<13> The granulating agent for powder according to <12>, wherein the water-soluble polymer contains a high-viscosity water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23°C, and a low-viscosity water-soluble polymer having a viscosity of 100 mPa·s or less in a 1% by mass aqueous solution at 23°C.
<14> A method for producing a granulated product, comprising a step of mixing at least one powder selected from the group consisting of inorganic powders and organic powders with an aqueous dispersion containing fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less and a water-soluble polymer, and granulating the mixture.

The present invention provides a granulating agent for powders that has low viscosity, can be mixed uniformly with powders, and produces granulated products with high particle hardness, as well as a granulated product using the powder granulating agent and a method for producing the same.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped onto a slurry containing fibrous cellulose having phosphorus oxo acid groups and pH. FIG. 2 is a graph showing the relationship between the amount of NaOH dropped onto a slurry containing fibrous cellulose having a carboxy group and the pH.

[Granulated product and its manufacturing method]
The granulated product of the present invention is prepared by granulating at least one powder selected from the group consisting of inorganic powders and organic powders with fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less and a binder component containing a water-soluble polymer. The granulated product of the present invention is granulated by the fibrous cellulose and water-soluble polymer functioning as binder components to bind the powders together. In the following description, the binder component (granulating agent) containing fibrous cellulose and water-soluble polymer is also referred to as the "binder component" or "binder." The aqueous dispersion containing fibrous cellulose and water-soluble polymer used during granulation is also referred to as the "binder solution." The term "binder solution" does not mean that the fibrous cellulose and water-soluble polymer are dissolved, but rather that at least one of the fibrous cellulose and the water-soluble polymer is dispersed.
According to the present invention, it is possible to provide a granulated product having high particle hardness and a method for producing the same. In addition, the granulated product of the present invention has high particle hardness and disintegrability in water, and is suitable for various applications such as food, cosmetics, pharmaceuticals, fertilizers, soil conditioners, and snow-melting agents.
While the exact reasons for the above-mentioned effects are unclear, some of the following may be considered. Conventionally, solutions of water-soluble polymers have been widely used as binders for granulating various powders and as binding agents for pharmaceutical formulations, but the hardness of the resulting granules remains to be improved. On the other hand, fine fibrous cellulose itself imparts appropriate granule hardness to the granules without excessively increasing the viscosity of the granulating agent. This allows the granulating agent to be uniformly mixed with the powder, resulting in granules with superior granule hardness. Furthermore, since fibrous cellulose containing fine fibrous cellulose is hydrophilic, the granules are likely to disintegrate in water. Furthermore, since fibrous cellulose is biodegradable, its use in fertilizers, soil conditioners, snow-melting agents, etc. is expected to reduce the environmental impact of binders. Furthermore, since fibrous cellulose is a naturally derived ingredient, its application in food, pharmaceuticals, and cosmetics is expected.
The present invention will be described in further detail below.

<Fibrous cellulose>
The fibrous cellulose of the present invention contains fine fibrous cellulose having a fiber width of 1,000 nm or less (hereinafter simply referred to as "fine fibrous cellulose" or "CNF"). In addition to the fine fibrous cellulose, the fibrous cellulose may also contain fibrous cellulose having a fiber width of more than 1,000 nm (hereinafter also referred to as "pulp fiber").

[Fine fibrous cellulose]
The fine fibrous cellulose is a fibrous cellulose having a fiber width of 1,000 nm or less. The fiber width of the fibrous cellulose can be measured, for example, by observation using an electron microscope.
From the viewpoints of the viscosity of the binder solution and economic efficiency, the content of fine fibrous cellulose in the fibrous cellulose is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass, and may be 100% by mass, but is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less.
As the fine fibrous cellulose, a fine fibrous cellulose containing an ionic group, which will be described later, and an unmodified fine fibrous cellulose may be used in combination.

The fiber width of the fine fibrous cellulose is 1,000 nm or less. The fiber width of the fine fibrous cellulose is, for example, preferably 2 nm or more and 1,000 nm or less, more preferably 2 nm or more and 100 nm or less, even more preferably 2 nm or more and 50 nm or less, and particularly preferably 2 nm or more and 10 nm or less. By making the fiber width of the fine fibrous cellulose 2 nm or more, it is possible to suppress the dissolution of the cellulose molecules in water, making it easier to achieve the effects of the fine fibrous cellulose, such as improved strength and rigidity.

The average fiber width of the fine fibrous cellulose is, for example, 1,000 nm or less. The average fiber width of the fine fibrous cellulose is preferably 2 nm or more and 1,000 nm or less, more preferably 2 nm or more and 100 nm or less, even more preferably 2 nm or more and 50 nm or less, and particularly preferably 2 nm or more and 10 nm or less. By making the average fiber width of the fine fibrous cellulose 2 nm or more, it is possible to suppress the dissolution of cellulose molecules in water, and more easily realize the effect of the fine fibrous cellulose in improving strength and rigidity. Note that the fine fibrous cellulose is, for example, single-filament cellulose.

The average fiber width of fine fibrous cellulose is measured, for example, using an electron microscope as follows. First, an aqueous suspension of fibrous cellulose with a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast onto a hydrophilically treated carbon film-coated grid to prepare a sample for TEM observation. When wide fibers are included, an SEM image of the surface cast onto glass may be observed. Next, electron microscope images are observed at magnifications of 1,000x, 5,000x, 10,000x, or 50,000x, depending on the width of the fibers to be observed. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.
(1) A line X is drawn at any point in the observed image, and 20 or more fibers intersect with the line X.
(2) Draw a line Y that intersects the line perpendicularly within the same image, and 20 or more fibers intersect the line Y.

For observation images that satisfy the above conditions, the widths of the fibers that intersect with lines X and Y are visually read. In this way, three or more sets of observation images are obtained of at least the surface portions that do not overlap each other. Next, for each image, the widths of the fibers that intersect with lines X and Y are read. In this way, the widths of at least 20 fibers x 2 x 3 = 120 fibers are read. The average of the read fiber widths is then taken as the average fiber width of the fibrous cellulose.

The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1,000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and even more preferably 0.1 μm or more and 600 μm or less. By keeping the fiber length within the above range, destruction of the crystalline regions of the fine fibrous cellulose can be suppressed. It also becomes possible to keep the slurry viscosity of the fine fibrous cellulose within an appropriate range. The fiber length of the fine fibrous cellulose can be determined, for example, by image analysis using TEM, SEM, or AFM.

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

The axial ratio (fiber length/fiber width) of the fine fibrous cellulose is not particularly limited, but is preferably 20 or more and 10,000 or less, and more preferably 50 or more and 1,000 or less. By setting the axial ratio at or above the lower limit, sufficient viscosity is likely to be obtained when a solvent dispersion is prepared. By setting the axial ratio at or below the upper limit, it is preferable in that handling, such as dilution, becomes easier when treating the fine fibrous cellulose as an aqueous dispersion, for example.

The fine fibrous cellulose in this embodiment has, for example, at least one of an ionic group and a nonionic group. From the viewpoint of improving the dispersibility of the fibers in the dispersion medium and increasing the defibration efficiency in the defibration treatment, it is more preferable that the fine fibrous cellulose has an ionic group. The ionic group may include, for example, either one or both of an anionic group and a cationic group. Furthermore, the nonionic group may include, for example, an alkyl group and an acyl group. In this embodiment, it is particularly preferable that the ionic group has an anionic group. Furthermore, the ionic group is preferably a group that is introduced into the fibrous cellulose via an ester bond or an ether bond, and more preferably a group that is introduced into the fibrous cellulose via an ester bond. In this case, the ester bond is preferably formed by dehydration condensation of the fibrous cellulose and a compound that becomes an ionic substituent.
The fine fibrous cellulose does not need to be subjected to a treatment for introducing ionic groups.

Examples of anionic groups as ionic groups include phosphorus oxo acid groups or substituents derived from phosphorus oxo acid groups (sometimes simply referred to as phosphorus oxo acid groups), carboxy groups or substituents derived from carboxy groups (sometimes simply referred to as carboxy groups), sulfone groups or substituents derived from sulfone groups (sometimes simply referred to as sulfone groups), xanthate groups, phosphonic groups, phosphine groups, and carboxyalkyl groups (including carboxymethyl groups). When a sulfone group or a substituent derived from a sulfone group is introduced via an ester bond, the substituent is sometimes referred to as a sulfur oxo acid group or a substituent derived from a sulfur oxo acid group (sometimes simply referred to as a sulfur oxo acid group). Among these, the anionic group is preferably at least one selected from the group consisting of a phosphorus oxoacid group, a substituent derived from a phosphorus oxoacid group, a carboxy group, a carboxymethyl group, a carboxyethyl group, a sulfur oxoacid group, and a substituent derived from a sulfur oxoacid group; more preferably at least one selected from the group consisting of a phosphorus oxoacid group, a substituent derived from a phosphorus oxoacid group, a carboxy group, a sulfur oxoacid group, and a substituent derived from a sulfur oxoacid group; and particularly preferably a phosphorus oxoacid group. Examples of cationic groups as ionic substituents include ammonium groups, phosphonium groups, and sulfonium groups. Among these, the cationic group is preferably an ammonium group.

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

In 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. All of the α and α' may be ^O- . The n α may all be the same or different. ^{β b+} is a monovalent or higher cation made of an organic or inorganic substance.
Each R is a hydrogen atom, a saturated linear hydrocarbon group, a saturated branched hydrocarbon group, a saturated cyclic hydrocarbon group, an unsaturated linear hydrocarbon group, an unsaturated branched hydrocarbon group, an unsaturated cyclic hydrocarbon group, an aromatic group, or a group derived from any of these. α in formula (1) may be a group derived from a cellulose molecular chain. Furthermore, in formula (1), n is preferably 1.

Examples of saturated linear hydrocarbon groups include, but are not limited to, methyl, ethyl, n-propyl, or n-butyl groups. Examples of saturated branched hydrocarbon groups include, but are not limited to, i-propyl or t-butyl groups. Examples of saturated cyclic hydrocarbon groups include, but are not limited to, cyclopentyl or cyclohexyl groups. Examples of unsaturated linear hydrocarbon groups include, but are not limited to, vinyl or allyl groups. Examples of unsaturated branched hydrocarbon groups include, but are not limited to, i-propenyl or 3-butenyl groups. Examples of unsaturated cyclic hydrocarbon groups include, but are not limited to, cyclopentenyl or cyclohexenyl groups. Examples of aromatic groups include, but are not limited to, phenyl or naphthyl groups.
Furthermore, examples of the derivative group in R include, but are not limited to, functional groups in which at least one functional group selected from the group consisting of a carboxy group, a carboxylate group (—COO ⁻ ), a hydroxy group, and an amino group is added to or substituted on the main chain or side chain of the above-mentioned hydrocarbon groups. 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 within the above range, the molecular weight of the phosphorus oxoacid group can be set within an appropriate range, facilitating penetration into the fiber raw material and increasing the yield of fine fibrous cellulose. When multiple R groups are present in formula (1) or when multiple types of substituents represented by formula (1) are introduced into the fibrous cellulose, the multiple R groups may be the same or different.

β ^b+ is a monovalent or higher cation composed of an organic or inorganic substance. Examples of the monovalent or higher cation composed of an organic substance include organic onium ions. Examples of the organic onium ions include organic ammonium ions and organic phosphonium ions. Examples of the organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of the organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions. Examples of the monovalent or higher cation composed of an inorganic substance include ions of alkali metals such as sodium, potassium, or lithium, ions of divalent metals such as calcium or magnesium, hydrogen ions, and ammonium ions. Note that when multiple β ^b+ groups exist in formula (1) or when multiple types of substituents represented by formula (1) are introduced into the fibrous cellulose, the multiple β ^b+ groups may be the same or different. Examples of the monovalent or higher cation composed of an organic or inorganic substance include, but are not limited to, sodium or potassium ions, which are resistant to yellowing when a fiber raw material containing β ^b+ is heated and are easy to use industrially.

More specific examples of the phosphorus oxo acid group or a substituent derived from a phosphorus oxo acid group include a phosphate group ( _-PO3H2 ), a salt of a phosphate group, a phosphorous acid ( _{phosphonic acid) group (-PO2H2 )} , and a salt of a _phosphite (phosphonic acid) group. Furthermore, the phosphorus oxo acid group or a substituent derived from a phosphorus oxo acid group may be a group in which a phosphate group is condensed (e.g., a pyrophosphate group), a group in which a phosphonic acid is condensed (e.g., a polyphosphonic acid group), a phosphate ester group (e.g., a monomethyl phosphate group, a polyoxyethylene alkyl phosphate group), an alkyl phosphonic acid group (e.g., a methylphosphonic acid group), or the like.

Furthermore, the sulfone group (sulfone group or a substituent derived from a sulfone group) is, for example, a substituent represented by the following formula (2). Multiple types of substituents represented by the following formula (2) may be introduced into each fibrous cellulose. In this case, the multiple introduced substituents represented by the following formula (2) may be the same or different.

In the structural formula, b and n are natural numbers, p is 0 or 1, and m is any number (where 1 = b × m). When n is 2 or greater, the multiple p's may be the same or different. In the structural formula, β ^b+ is a monovalent or higher cation composed of an organic or inorganic substance. Examples of the monovalent or higher cation composed of an organic substance include organic onium ions. Examples of the organic onium ions include organic ammonium ions and organic phosphonium ions. Examples of the organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of the organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions. Examples of the monovalent or higher cation composed of an inorganic substance include ions of alkali metals such as sodium, potassium, or lithium, ions of divalent metals such as calcium or magnesium, hydrogen ions, and ammonium ions. When multiple types of substituents represented by the above formula (2) are introduced into the fibrous cellulose, the multiple β ^b+ may be the same or different. As the monovalent or higher cations consisting of organic or inorganic substances, sodium or potassium ions are preferred, as they are less likely to yellow when the fiber raw material containing β ^b+ is heated and are easy to use industrially, but there are no particular limitations.

The amount of ionic groups introduced into the fine fibrous cellulose is, for example, preferably 0.10 mmol/g or more per 1 g (mass) of fine fibrous cellulose, more preferably 0.20 mmol/g or more, even more preferably 0.50 mmol/g or more, and particularly preferably 1.00 mmol/g or more. Furthermore, the amount of ionic groups introduced into the fine fibrous cellulose 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, even more preferably 3.50 mmol/g or less, and even more preferably 3.00 mmol/g or less. By setting the amount of ionic groups introduced within the above range, it is possible to facilitate the refinement of the fiber raw material and to improve the stability of the fine fibrous cellulose. Furthermore, by setting the amount of ionic groups introduced within the above range, it is possible to exhibit good properties in various applications, such as a thickener for fine fibrous cellulose.
Here, the denominator in the unit mmol/g indicates the mass of the fine fibrous cellulose when the counter ion of the ionic group is a hydrogen ion (H ⁺ ).

The amount of ionic groups introduced into the fibrous cellulose can be measured, for example, by neutralization titration, in which an alkali such as an aqueous sodium hydroxide solution is added to a slurry containing the obtained fibrous cellulose, and the amount introduced is measured by determining the change in pH.
FIG. 1 is a graph showing the relationship between the amount of NaOH added dropwise to fibrous cellulose having phosphorus oxo acid groups and pH.

1 is a graph showing the relationship between the amount of NaOH added dropwise to a slurry containing fibrous cellulose having phosphorus oxo acid groups and pH. The amount of phosphorus oxo acid groups introduced into the fibrous cellulose is measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the measurement object may be subjected to a defibration treatment similar to the defibration treatment step described below before the treatment with the strongly acidic ion exchange resin.
Next, the change in pH is observed while adding aqueous sodium hydroxide solution, and a titration curve such as that shown in the upper part of Figure 1 is obtained. The titration curve shown in the upper part of Figure 1 plots the measured pH against the amount of alkali added, while the titration curve shown in the lower part of Figure 1 plots the pH increment (derivative value) (1/mmol) against the amount of alkali added. In this neutralization titration, two points are identified in the curve plotting the measured pH against the amount of alkali added, where the increment (derivative value of pH with respect to the amount of alkali added) is maximized. Of these, the first maximum point of the increment after starting to add the alkali is called the first endpoint, and the next maximum point of the increment is called the second endpoint. The amount of alkali required from the start of titration to the first endpoint is equal to the amount of first dissociated acid of the fibrous cellulose contained in the slurry used for titration, the amount of alkali required from the first endpoint to the second endpoint is equal to the amount of second dissociated acid of the fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the start of titration to the second endpoint is equal to the total amount of dissociated acid of the fibrous cellulose contained in the slurry used for titration.The value obtained by dividing the amount of alkali required from the start of titration to the first endpoint by the solids content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol/g).Note that when simply referring to the amount of phosphorus oxo acid group introduced (or amount of phosphorus oxo acid group), it refers to the amount of first dissociated acid.
In FIG. 1 , the region from the start of titration to the first endpoint is referred to as the first region, and the region from the first endpoint to the second endpoint is referred to as the second region. For example, when the phosphorus oxoacid group is a phosphate group and this phosphate group undergoes condensation, the amount of weakly acidic groups in the phosphorus oxoacid group (also referred to herein as the second dissociated acid amount) appears to decrease, and the amount of alkali required in the second region is less than the amount of alkali required in the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxoacid group (also referred to herein as the first dissociated acid amount) corresponds to the amount of phosphorus atoms regardless of whether condensation occurs. Furthermore, when the phosphorus oxoacid group is a phosphite group, the phosphorus oxoacid group no longer contains weakly acidic groups, so the amount of alkali required in the second region is reduced or may even be zero. In this case, there is only one point on the titration curve where the pH increment is maximized.
The above-mentioned amount of introduced phosphorus oxoacid groups (mmol/g) indicates the amount of phosphorus oxoacid groups possessed by the acid-form fibrous cellulose (hereinafter referred to as the amount of phosphorus oxoacid groups (acid form)), since the denominator indicates the mass of the acid-form fibrous cellulose. On the other hand, when the counter ions of the phosphorus oxoacid groups are substituted with any cation C so as to be charge equivalent, the amount of phosphorus oxoacid groups possessed by the fibrous cellulose with the cation C as the counter ion (hereinafter referred to as the amount of phosphorus oxoacid groups (C form)) can be determined by converting the denominator to the mass of the fibrous cellulose when the cation C is the counter ion.
That is, it is calculated using the following formula.
Amount of phosphorus oxoacid group (C type)=Amount of phosphorus oxoacid group (acid type)/{1+(W−1)×A/1000}
A [mmol/g]: total amount of anions derived from phosphorus oxoacid groups in the fibrous cellulose (the sum of the amount of strongly acidic groups and the amount of weakly acidic groups in the phosphorus oxoacid groups)
W: Formula weight per valence of cation C (for example, Na is 23, Al is 9)

FIG. 2 is a graph showing the relationship between the amount of NaOH dropped onto fibrous cellulose having a carboxy group and pH.
The amount of carboxyl groups introduced into the fibrous cellulose can be measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the measurement object may be subjected to a defibration treatment similar to the defibration treatment step described below before treatment with the strongly acidic ion exchange resin. Next, the change in pH is observed while adding a sodium hydroxide aqueous solution, and a titration curve such as that shown in FIG. 2 is obtained. If necessary, the measurement object may be subjected to a defibration treatment similar to the defibration treatment step described below.
As shown in Figure 2, in this neutralization titration, a single point is observed where the increment (the differential value of pH with respect to the amount of alkali added) is maximum on the curve plotting the measured pH against the amount of alkali added. This maximum increment is called the first end point. Here, the region from the start of titration to the first end point in Figure 2 is called the first region. The amount of alkali required in the first region is equal to the amount of carboxyl groups in the slurry used for titration. The amount of alkali introduced (mmol/g) was then calculated by dividing the amount of alkali (mmol) required in the first region of the titration curve by the solids content (g) in the fine fibrous cellulose-containing slurry to be titrated.
The above-mentioned amount of carboxyl groups introduced (mmol/g) indicates the amount of substituents per 1 g of fibrous cellulose mass when the counter ion of the carboxyl group is a hydrogen ion (H ⁺ ) (hereinafter referred to as the amount of carboxyl groups (acid type)).

The above-mentioned amount of carboxy groups introduced (mmol/g) indicates the amount of carboxy groups possessed by the acid-form fibrous cellulose (hereinafter referred to as the amount of carboxy groups (acid form)), since the denominator is the mass of the acid-form fibrous cellulose. On the other hand, when the counter ions of the carboxy groups are substituted with any cation C so as to be charge equivalent, the amount of carboxy groups possessed by the fibrous cellulose with the cation C as the counter ion (hereinafter referred to as the amount of carboxy groups (C form)) (mmol/g) can be determined by converting the denominator to the mass of the fibrous cellulose when the cation C is the counter ion.
That is, it is calculated using the following formula.
Amount of carboxyl group (C type)=Amount of carboxyl group (acid type)/{1+(W-1)×(Amount of carboxyl group (acid type))/1000}
W: Formula weight per valence of cation C (for example, Na is 23, Al is 9)

When measuring the amount of substituents such as phosphorus oxoacid groups or carboxyl groups using titration, adding too much sodium hydroxide solution or titrating too quickly can result in lower than expected amounts of substituents and inaccurate values. An appropriate amount and titration interval is, for example, titrating 10 to 50 μL of 0.1 N sodium hydroxide solution every 5 to 30 seconds. To eliminate the effects of carbon dioxide dissolved in the fibrous cellulose-containing slurry, it is also recommended to measure while blowing an inert gas such as nitrogen gas into the slurry, for example, from 15 minutes before the start of titration until the end of titration.

The amount of sulfonic groups introduced into the fibrous cellulose is determined by wet ashing the obtained fibrous cellulose with perchloric acid and concentrated nitric acid, diluting it at an appropriate ratio, and measuring the amount of sulfur by ICP emission spectrometry.
The amount of sulfur divided by the bone dry mass of the fibrous cellulose sample is taken as the amount of sulfonic groups (unit: mmol/g).

The above-mentioned method for measuring the amount of ionic groups applies to fine fibrous cellulose with a fiber width of 1,000 nm or less. When measuring the amount of ionic groups in pulp fibers with a fiber width of more than 1,000 nm, the pulp fibers must be refined before measurement.

[Method for producing fine fibrous cellulose]
(cellulose-containing fiber materials)
Fine fibrous cellulose is produced from a fiber raw material containing cellulose.
The cellulose-containing fiber raw material is not particularly limited, but pulp is preferably used because of its ease of availability and low cost. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include, but are not limited to, chemical pulps such as 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 pulp (OKP); semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP); and mechanical pulps such as groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP). Examples of non-wood pulp include, but are not limited to, cotton-based pulps such as cotton linters and cotton lint, and non-wood pulps such as hemp, wheat straw, and bagasse. The deinked pulp is not particularly limited, but may be, for example, deinked pulp made from recycled paper. The pulp of this embodiment may be one of the above types alone or a mixture of two or more types.
Among the above pulps, wood pulp and deinked pulp are preferred from the viewpoint of ease of availability. Furthermore, among wood pulps, chemical pulp is more preferred, and kraft pulp and sulfite pulp are even more preferred, from the viewpoint of a high cellulose content, a high yield of fine fibrous cellulose during defibration treatment, and small decomposition of cellulose in the pulp to obtain long-fiber fine fibrous cellulose with a large axial ratio. Note that the use of long-fiber fine fibrous cellulose with a large axial ratio tends to increase viscosity.
As a fiber raw material containing cellulose, for example, cellulose contained in sea squirts and bacterial cellulose produced by acetic acid bacteria can be used.
Furthermore, instead of fiber raw materials containing cellulose, fibers formed from linear nitrogen-containing polysaccharide polymers such as chitin and chitosan can also be used.

To obtain fibrous cellulose having the above-described ionic substituents introduced therein, it is preferable to have an ionic substituent introduction step, in which ionic substituents are introduced into the above-described cellulose-containing fiber raw material, followed in this order by a washing step, an alkali treatment step (neutralization step), and a defibration treatment step. Alternatively, an acid treatment step may be included instead of or in addition to the washing step. Examples of ionic substituent introduction steps include a phosphorus oxo acid group introduction step, a carboxy group introduction step, a sulfonic acid group introduction step, a xanthate group introduction step, a phosphonic or phosphine group introduction step, a sulfonic group introduction step, and a cationic group introduction step. Each step is described below.

(Ionic group introduction step)
- Phosphorus oxo acid group introduction step -
The phosphorus oxo acid group introduction step is a step in which at least one compound (hereinafter also referred to as "compound A") selected from compounds capable of introducing phosphorus oxo acid groups by reacting with hydroxyl groups in a cellulose-containing fiber raw material is allowed to act on the cellulose-containing fiber raw material, thereby producing a phosphorus oxo acid group-introduced fiber.
In the phosphate group introduction step according to this embodiment, the reaction of the cellulose-containing fiber raw material with compound A may be carried out in the presence of at least one selected from urea and its derivatives (hereinafter also referred to as "compound B"). Alternatively, the cellulose-containing fiber raw material may be reacted with compound A in the absence of compound B.
One example of a method for reacting compound A with a fiber raw material in the presence of compound B is a method in which compound A and compound B are mixed with a fiber raw material in a dry, wet, or slurry state. Among these methods, using a fiber raw material in a dry or wet state is preferred, as this provides high reaction uniformity, and using a fiber raw material in a dry state is particularly preferred. The form of the fiber raw material is not particularly limited, but is preferably in the form of a cotton or thin sheet. Compound A and compound B may be added to the fiber raw material in the form of a powder, a solution dissolved in a solvent, or a melted state heated to or above their melting point. Among these methods, adding compound A and compound B in the form of a solution dissolved in a solvent, particularly an aqueous solution, is preferred, as this provides high reaction uniformity. Compound A and compound B may be added to the fiber raw material simultaneously, separately, or as a mixture. The method for adding compound A and compound B is not particularly limited, but when compound A and 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 removed, or the solution may be added dropwise to the fiber raw material. Alternatively, the required amounts of compound A and compound B may be added to the fiber raw material, or excess amounts of compound A and compound B may be added to the fiber raw material, and then the excess compound A and compound B may be removed by squeezing or filtration.

The compound A used in this embodiment may be any compound that has a phosphorus atom and can form an ester bond with cellulose, including, but not limited to, phosphoric acid or a salt thereof, phosphorous acid or a salt thereof, dehydrated condensed phosphoric acid or a salt thereof, and phosphoric anhydride (diphosphorus pentoxide). Phosphoric acid can be used with various purities, such as 100% phosphoric acid (orthophosphoric acid) or 85% phosphoric acid. Phosphorous acid can be, for example, 99% phosphorous acid (phosphonic acid). Dehydrated condensed phosphoric acid is a compound in which two or more molecules of phosphoric acid are condensed by a dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Phosphates, phosphites, and dehydrated condensed phosphates include lithium salts, sodium salts, potassium salts, and ammonium salts of phosphoric acid, phosphorous acid, or dehydrated condensed phosphoric acid, which can be neutralized to various degrees.
Among these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred, and phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, and ammonium dihydrogen phosphate are more preferred, from the viewpoints of high efficiency in introducing phosphate groups, easier improvement of defibration efficiency in the defibration step described below, low cost, and ease of industrial application.
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 into the amount of phosphorus atoms, the amount of phosphorus atoms added to the fiber raw material (bone dry mass) is preferably 0.5% by mass or more and 100% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and even more preferably 2% by mass or more and 30% by mass or less. By setting the amount of phosphorus atoms added to the fiber raw material within the above range, the yield of fine fibrous cellulose can be further improved. On the other hand, by setting the amount of phosphorus atoms added to the fiber raw material to the above upper limit or less, a balance can be achieved between the yield improvement effect and costs.

As described above, the compound B used in this embodiment is at least one selected from urea and its derivatives. Examples of the compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, and 1-ethylurea.
From the viewpoint of improving the uniformity of the reaction, it is preferable to use an aqueous solution of compound B. Furthermore, 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 relative to the fiber raw material (bone dry mass) is not particularly limited, but is preferably, for example, 1 mass % or more and 500 mass % or less, more preferably 10 mass % or more and 400 mass % or less, and even more preferably 100 mass % or more and 350 mass % or less.

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

In the phosphorus oxo acid group introduction step, compound A or the like is preferably added to or mixed with the fiber raw material, and then the fiber raw material is subjected to a heat treatment. The heat treatment temperature is preferably selected so that the phosphorus oxo acid group can be efficiently introduced while suppressing thermal decomposition and hydrolysis of the fiber. The heat treatment temperature is preferably, for example, 50°C to 300°C, more preferably 100°C to 250°C, and even more preferably 130°C to 200°C. Furthermore, various types of equipment with heat transfer media can be used for the heat treatment, including, for example, agitator dryers, rotary dryers, disk dryers, roll-type heaters, plate-type heaters, fluidized-bed dryers, band dryers, filtration dryers, vibration fluidized dryers, flash dryers, hot-air dryers, reduced-pressure dryers, infrared heaters, far-infrared heaters, microwave heaters, and high-frequency dryers.

In the heat treatment according to this embodiment, for example, a method of adding compound A to a thin sheet-like fiber raw material by a method such as impregnation and then heating the material, or a method of heating the fiber raw material while kneading or stirring the fiber raw material and compound A in a kneader or the like, can be employed. This makes it possible to suppress unevenness in the concentration of compound A in the fiber raw material and to more uniformly introduce phosphate groups onto the surface of the cellulose fibers contained in the fiber raw material. This is thought to be because, when water molecules move to the surface of the fiber raw material as it is dried, the dissolved compound A is attracted to the water molecules by surface tension and is prevented from migrating to the surface of the fiber raw material in the same way (i.e., causing unevenness in the concentration of compound A).
Furthermore, the heating device used for the heat treatment is preferably one that can constantly discharge, to the outside of the system, moisture contained in the slurry and moisture generated in the dehydration condensation (phosphorylation) reaction between compound A and hydroxyl groups contained in cellulose or the like in the fiber raw material. Examples of such a heating device include a hot air dryer such as a blower oven. Constantly discharging moisture from the system can suppress the hydrolysis reaction of phosphate ester bonds, which is the reverse reaction of phosphate esterification, and also suppress acid hydrolysis of sugar chains in the fiber. This makes it possible to obtain fine fibrous cellulose with a high axial ratio.
The heat treatment time is preferably from 1 second to 300 minutes after the water content has been substantially removed from the fiber raw material, more preferably from 1 second to 1,000 seconds, and even more preferably from 10 seconds to 800 seconds. In this embodiment, the amount of phosphorus oxo acid groups introduced can be kept within a preferred range by setting the heating temperature and heating time within appropriate ranges.

The phosphorus oxo acid group introduction step needs to be performed at least once, but can also be repeated two or more times. By performing the phosphorus oxo acid group introduction step two or more times, a large number of phosphorus oxo acid groups can be introduced into the fiber raw material. In this embodiment, a preferred example is when the phosphorus oxo acid group introduction step is performed two times.

The amount of phosphorus oxoacid groups introduced into the fiber raw material is preferably 0.10 mmol/g or more per 1 g (mass) of fine fibrous cellulose, more preferably 0.20 mmol/g or more, even more preferably 0.50 mmol/g or more, and particularly preferably 1.00 mmol/g or more. Furthermore, the amount of phosphorus oxoacid groups introduced into the fiber raw material is preferably 5.20 mmol/g or less per 1 g (mass) of fine fibrous cellulose, more preferably 3.65 mmol/g or less, and even more preferably 3.00 mmol/g or less. By keeping the amount of phosphorus oxoacid groups introduced within the above range, it is possible to facilitate the micronization of the fiber raw material and improve the stability of the fine fibrous cellulose.

-Carboxy group introduction step-
The carboxyl group introduction process is carried out by treating a fiber raw material containing cellulose with an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, or TEMPO oxidation treatment, or with a compound having a carboxylic acid-derived group or a derivative thereof, or an acid anhydride of a compound having a carboxylic acid-derived group or a derivative thereof.
Examples of compounds having a group derived from carboxylic acid include, but are not limited to, dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. Examples of derivatives of compounds having a group derived from carboxylic acid include, but are not limited to, imidized products of acid anhydrides of compounds having carboxy groups, and derivatives of acid anhydrides of compounds having carboxy groups. Examples of imidized products of acid anhydrides of compounds having carboxy groups include, but are not limited to, imidized products of dicarboxylic acid compounds such as maleimide, succinimide, and phthalimide.

Acid anhydrides of compounds having a group derived from carboxylic acid include, but are not limited to, acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Furthermore, derivatives of acid anhydrides of compounds having a group derived from carboxylic acid include, but are not limited to, acid anhydrides of compounds having carboxy groups such as dimethylmaleic anhydride, diethylmaleic anhydride, and diphenylmaleic anhydride, in which at least some of the hydrogen atoms have been substituted with substituents such as alkyl groups or phenyl groups.

When TEMPO oxidation treatment is performed in the carboxyl group introduction step, it is preferable to perform the treatment under conditions of a pH of 6 or higher and 8 or lower. This type of treatment is also called a neutral TEMPO oxidation treatment. The neutral TEMPO oxidation treatment can be performed, for example, by adding pulp as the fiber raw material, a nitroxy radical such as TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst, and sodium hypochlorite as a sacrificial reagent to a sodium phosphate buffer solution (pH = 6.8). Furthermore, by adding sodium chlorite, aldehydes generated during the oxidation process can be efficiently oxidized to carboxyl groups.
The TEMPO oxidation treatment may be carried out under conditions of a pH of 10 to 11. Such a treatment is also called alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be carried out, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a co-catalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material.
The amount of carboxyl groups introduced into the fiber raw material varies depending on the type of substituent, but for example, when carboxyl groups are introduced by TEMPO oxidation, it is preferably 0.10 mmol/g or more per 1 g (mass) of fine fibrous cellulose, more preferably 0.20 mmol/g or more, even more preferably 0.50 mmol/g or more, and particularly preferably 0.90 mmol/g or more. It is also preferably 3.65 mmol/g or less, more preferably 3.00 mmol/g or less, even more preferably 2.5 mmol/g or less, even more preferably 2.20 mmol/g or less, and particularly preferably 2.00 mmol/g or less. Alternatively, when the substituent is a carboxymethyl group, it may be 5.8 mmol/g or less per 1 g (mass) of fine fibrous cellulose.

- Sulfonic group introduction step -
The ionic substituent introduction step may include a sulfonic acid introduction step, in which a hydroxyl group in a fiber raw material containing cellulose reacts with a sulfur oxoacid to obtain a cellulose fiber having a sulfonic acid group (a sulfonic acid-introduced fiber).

In the sulfonic acid group introduction step, instead of compound A in the above-described <Phosphorus Oxo Acid Group Introduction Step>, at least one compound (hereinafter also referred to as "compound C") selected from compounds capable of introducing sulfonic acid groups by reacting with hydroxyl groups in cellulose-containing fiber raw materials is used. Compound C may be any compound containing a sulfur atom and capable of forming an ester bond with cellulose, including, but not limited to, sulfuric acid or its salts, sulfurous acid or its salts, and sulfuric acid amides. Sulfuric acid of various purities can be used, such as 96% sulfuric acid (concentrated sulfuric acid). Sulfurous acid can be 5% aqueous sulfurous acid. Sulfates or sulfites include lithium, sodium, potassium, and ammonium salts of sulfates or sulfites, which can be neutralized to various degrees. Sulfamic acid or other sulfuric acid amides can be used. In the sulfonic acid group introduction step, it is preferable to use compound B in the above-described <Phosphorus Oxo Acid Group Introduction Step>.

In the sulfonic acid introduction process, the cellulose raw material is preferably mixed with an aqueous solution containing sulfur oxoacid and urea and/or a urea derivative, and then the cellulose raw material is subjected to a heat treatment. The heat treatment temperature is preferably selected so that sulfonic acid groups can be efficiently introduced while suppressing thermal decomposition and hydrolysis 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 substantially all moisture is removed. Therefore, the heat treatment time varies depending on the amount of moisture contained in the cellulose raw material and the amount of aqueous solution containing sulfur oxoacid and urea and/or a urea derivative added, but is preferably 10 seconds or more and 10,000 seconds or less. Heat treatment can be performed using equipment with a variety of heat media, including hot air dryers, agitator dryers, rotary dryers, disk dryers, roll-type heaters, plate-type heaters, fluidized bed dryers, band dryers, filtration dryers, vibration fluidized dryers, pneumatic dryers, reduced pressure dryers, infrared heaters, far-infrared heaters, microwave heaters, and high-frequency dryers.

The amount of sulfonic groups introduced into the cellulose raw material is preferably 0.05 mmol/g or more, more preferably 0.10 mmol/g or more, even more preferably 0.20 mmol/g or more, even more preferably 0.40 mmol/g or more, and particularly preferably 0.50 mmol/g or more. Furthermore, the amount of sulfonic groups introduced into the cellulose raw material is preferably 5.00 mmol/g or less, more preferably 3.00 mmol/g or less. By keeping the amount of sulfonic groups introduced within the above range, it is possible to facilitate the micronization of cellulose fibers in the micronization treatment process and increase the stability of the fine fibrous cellulose.

- Oxidation step using a chlorine-based oxidizing agent (second carboxyl group introduction step) -
The ionic substituent introduction step may include an oxidation step using a chlorine-based oxidizing agent, in which a chlorine-based oxidizing agent is added to a wet or dry fiber raw material having a hydroxyl group to cause a reaction, thereby introducing a carboxyl group into the fiber raw material.

Examples of chlorine-based oxidizing agents include hypochlorous acid, hypochlorites, chlorous acid, chlorites, chloric acid, chlorates, perchloric acid, perchlorates, and chlorine dioxide. From the standpoints of substituent introduction efficiency, defibration efficiency, cost, and ease of handling, sodium hypochlorite, sodium chlorite, and chlorine dioxide are preferred chlorine-based oxidizing agents. When adding a chlorine-based oxidizing agent, it may be added directly to the fiber raw material as a reagent (solid or liquid), or it may be dissolved in an appropriate solvent and added.

In the oxidation process using a chlorine-based oxidizing agent, the concentration of the chlorine-based oxidizing agent in the solution, converted into effective chlorine concentration, is preferably 1% by mass or more and 1,000% by mass or less, more preferably 5% by mass or more and 500% by mass or less, and even more preferably 10% by mass or more and 100% by mass or less. The amount of chlorine-based oxidizing agent added per 100 parts by mass of fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 10 parts by mass or more and 10,000 parts by mass or less, and even more preferably 100 parts by mass or more and 5,000 parts by mass or less.

The reaction time with the chlorine-based oxidizing agent in the oxidation step using the chlorine-based oxidizing agent varies depending on the reaction temperature, but is preferably from 1 minute to 1,000 minutes, more preferably from 10 minutes to 500 minutes, and even more preferably from 20 minutes to 400 minutes. The pH during the reaction is preferably from 5 to 15, more preferably from 7 to 14, and even more preferably from 9 to 13. At the start of the reaction, the pH is preferably maintained constant (for example, at pH 11) during the reaction by adding hydrochloric acid or sodium hydroxide as appropriate. After the reaction, excess reaction reagents, by-products, etc. may be washed away with water by filtration or other methods.

-Xanthate group introduction step (xanthogen acid esterification step)-
The ionic substituent introduction step may include, for example, a xanthate group introduction step (hereinafter also referred to as a xanthation step). In the xanthation step, carbon disulfide and an alkali compound are added to a wet or dry fiber raw material having a hydroxyl group to cause a reaction, thereby introducing a xanthate group into the fiber raw material. Specifically, carbon disulfide is added to a fiber raw material that has been converted into alkali cellulose by the method described below, and the reaction is carried out.

<<Alkali cellulose conversion>>
When introducing ionic substituents into a fiber raw material, it is preferable to convert the cellulose contained in the fiber raw material into alkali cellulose by treating the cellulose with an alkaline solution. This treatment causes ionic dissociation of some of the hydroxyl groups in the cellulose, thereby increasing the nucleophilicity (reactivity). The alkaline compound contained in the alkaline solution is not particularly limited and may be an inorganic alkaline compound or an organic alkaline compound. Due to their high versatility, it is preferable to use, for example, sodium hydroxide, potassium hydroxide, tetraethylammonium hydroxide, or tetrabutylammonium hydroxide. The conversion into alkali cellulose may be carried out simultaneously with the introduction of the ionic substituents, before the introduction, or at both the same time.

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

The alkali concentration in the alkaline solution is preferably 0.01 mol/L or more and 4 mol/L or less, more preferably 0.1 mol/L or more and 3 mol/L or less, and even more preferably 1 mol/L or more and 2.5 mol/L or less. In particular, when the treatment temperature for alkali cellulose formation is less than 10°C, the alkali concentration is preferably 1 mol/L or more and 2 mol/L or less.

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

By adjusting the type of alkaline solution, treatment temperature, concentration, and immersion time as described above, it is possible to suppress the penetration of the alkaline solution into the crystalline regions of the cellulose, making it easier to maintain the cellulose type I crystalline structure and increasing the yield of fine fibrous cellulose.

When the introduction of ionic substituents and the conversion to alkali cellulose are not carried out simultaneously, the conversion to alkali cellulose is preferably carried out prior to the introduction of ionic substituents. In this case, the alkali cellulose obtained in the alkali cellulose conversion process is preferably subjected to solid-liquid separation and water removal using a common deliquoring method such as centrifugation or filtration. This improves the reaction efficiency in the subsequent ionic substituent introduction step. The cellulose fiber concentration after solid-liquid separation is preferably 5% to 50%, more preferably 10% to 40%, and even more preferably 15% to 35%.

-Phosphonic or phosphine group introduction step (phosphoalkylation step)-
The ionic substituent introduction step may include a phosphonic or phosphine group introduction step (phosphoalkylation step). In the phosphoalkylation step, a compound having a reactive group and a phosphonic or phosphine group (compound E _A ) as an essential component, and an alkali compound and a compound B selected from the above-mentioned urea and its derivatives as optional components, are added to a wet or dry fiber raw material having a hydroxyl group and reacted to introduce a phosphonic or phosphine group into the fiber raw material.

Examples of the reactive group include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
Examples of the compound _EA include vinylphosphonic acid, phenylvinylphosphonic acid, phenylvinylphosphinic acid, etc. From the viewpoints of the efficiency of introducing a substituent, and therefore the defibration efficiency, cost, and ease of handling, it is preferable that the compound _EA is vinylphosphonic acid.
Furthermore, as an optional component, it is also preferable to use the compound B in the above-mentioned <Phosphorus oxo acid group introduction step> in the same manner, and the amount added is also preferably as described above.

When compound _EA is added, it may be added to the fiber raw material as a reagent (solid or liquid) as it is, or may be dissolved in an appropriate solvent and added. The fiber raw material is preferably converted into alkali cellulose in advance or simultaneously with the reaction. The method for converting into alkali cellulose is as described above.

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

The amount of compound E _A added per 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably between 1 minute and 1,000 minutes, more preferably between 10 minutes and 500 minutes, and even more preferably between 20 minutes and 400 minutes. After the reaction, excess reaction reagents, by-products, etc. may be washed away with water or removed by filtration, etc.

-Sulfonic acid group introduction step (sulfoalkylation step) (second sulfonic acid group introduction step)-
The ionic substituent introduction step may include a sulfonic group introduction step (sulfoalkylation step). In the sulfoalkylation, a compound (compound E _B ) having a reactive group and a sulfonic group as an essential component, and an optional component, an alkali compound and a compound B selected from the above-mentioned urea and its derivatives, are added to a wet or dry fiber raw material having a hydroxyl group and reacted to introduce a sulfonic group into the fiber raw material.

Examples of the reactive group include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
Examples of compound E _B include sodium 2-chloroethanesulfonate, sodium vinylsulfonate, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, etc. Among these, from the viewpoints of the efficiency of introducing substituents, and therefore the defibration efficiency, cost, and ease of handling, it is preferable that compound E _B be sodium vinylsulfonate.
Furthermore, as an optional component, it is also preferable to use the compound B in the above-mentioned <Phosphorus oxo acid group introduction step> in the same manner, and the amount added is also preferably as described above.

When compound E _B is added, it may be added to the fiber raw material as a reagent (solid or liquid) as it is, or may be dissolved in an appropriate solvent and added. The fiber raw material is preferably converted into alkali cellulose in advance or simultaneously with the reaction. The method for converting into alkali cellulose is as described above.

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

The amount of compound E _B added per 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably between 1 minute and 1,000 minutes, more preferably between 10 minutes and 500 minutes, and even more preferably between 15 minutes and 400 minutes. After the reaction, excess reaction reagents, by-products, etc. may be washed away with water or removed by filtration, etc.

-Carboxyalkylation step (third carboxy group introduction step)-
The ionic substituent introduction step may include a carboxyalkylation step, in which a compound having a reactive group and a carboxy group (compound E _C ) as an essential component, an alkali compound, and a compound B selected from the aforementioned urea and its derivatives as optional components, are added to a wet or dry fiber raw material having a hydroxyl group and reacted to introduce a carboxy group into the fiber raw material.

Examples of the reactive group include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
As the compound E _C , monochloroacetic acid, sodium monochloroacetate, 2-chloropropionic acid, 3-chloropropionic acid, sodium 2-chloropropionate, and sodium 3-chloropropionate are preferred from the standpoints of the efficiency of introducing substituents, and therefore the defibration efficiency, cost, and ease of handling.
Furthermore, as an optional component, it is also preferable to use the compound B in the above-mentioned <Phosphorus oxo acid group introduction step> in the same manner, and the amount added is also preferably as described above.

When compound E _C is added, it may be added to the fiber raw material as a reagent (solid or liquid) as it is, or may be dissolved in an appropriate solvent and added. The fiber raw material is preferably converted into alkali cellulose in advance or simultaneously with the reaction. The method for converting into alkali cellulose is as described above.

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

The amount of compound E _C added per 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably between 1 minute and 1,000 minutes, more preferably between 3 minutes and 500 minutes, and even more preferably between 5 minutes and 400 minutes. After the reaction, excess reaction reagents, by-products, etc. may be washed away with water and removed by filtration or other methods.

<Cationic group introduction step (cationization step)>
A compound having a reactive group and a cationic group (compound E _D ) as an essential component, and an alkaline compound and a compound B selected from the above-mentioned urea and its derivatives as optional components, are added to a wet or dry fiber raw material having a hydroxyl group and reacted to introduce a cationic group into the fiber raw material.

Examples of the reactive group include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
Examples of the cationic group include an ammonium group, a phosphonium group, a sulfonium group, etc. Among these, the cationic group is preferably an ammonium group.
As the compound E _D , glycidyl trimethyl ammonium chloride, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, etc. are preferred from the viewpoints of the efficiency of introducing substituents, and hence the defibration efficiency, cost, and ease of handling.
Furthermore, it is also preferable to use the compound B in the above-mentioned <Phosphorus Oxo Acid Group Introduction Step> as an optional component in the same manner. The amount added is also preferably as described above.

When compound E or _D is added, it may be added to the fiber raw material as a reagent (solid or liquid) as is, or may be dissolved in an appropriate solvent and added. The fiber raw material is preferably converted into alkali cellulose in advance or simultaneously with the reaction. The method for converting into alkali cellulose is as described above.

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

The amount of compound E _D added per 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably between 1 minute and 1,000 minutes, more preferably between 5 minutes and 500 minutes, and even more preferably between 10 minutes and 400 minutes. After the reaction, excess reaction reagents, by-products, etc. may be washed away with water or removed by filtration, etc.

(Cleaning process)
In the method for producing fine fibrous cellulose according to the present embodiment, the ionic group-introduced fibers may be subjected to a washing step as needed. The washing step is carried out by washing the ionic group-introduced fibers with water or an organic solvent, for example. The washing step may be carried out after each step described below, and the number of washing steps carried out in each washing step is not particularly limited.

(Alkali treatment step)
When producing fine fibrous cellulose, the fiber raw material may be subjected to an alkali treatment between the ionic group introduction step and the defibration step described below. The alkali treatment method is not particularly limited, but an example thereof is a method of immersing the ionic 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. In this embodiment, it is preferable to use, for example, sodium hydroxide or potassium hydroxide as the alkaline compound because of their high versatility. The solvent contained in the alkaline solution may be either water or an organic solvent. Among these, the solvent contained in the alkaline solution is preferably water or a polar solvent including a polar organic solvent such as an alcohol, and more preferably an aqueous solvent including at least water. As the alkaline solution, for example, an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution is preferable because of their high versatility.
The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably, for example, from 5° C. to 80° C., and more preferably from 10° C. to 60° C. The immersion time of the ionic group-introduced fiber in the alkaline solution in the alkaline treatment step is not particularly limited, but is, for example, preferably from 5 minutes to 30 minutes, and more preferably from 10 minutes to 20 minutes. The amount of alkaline solution used in the alkaline treatment is not particularly limited, but is, for example, preferably from 100% by mass to 100,000% by mass, and more preferably from 1,000% by mass to 25,000% by mass, based on the absolute dry mass of the ionic group-introduced fiber.

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

(Acid treatment step)
When producing fine fibrous cellulose, the fiber raw material may be subjected to an acid treatment between the step of introducing ionic groups and the defibration treatment step described below. For example, the ionic group introduction step, acid treatment step, alkali treatment step, and defibration treatment step may be performed in this order.
The acid treatment method is not particularly limited, but examples include a method of immersing the fiber raw material in an acid-containing acid solution. The concentration of the acid solution used is not particularly limited, but is preferably 10% by mass or less, and more preferably 5% by mass or less. The pH of the acid solution used is also not particularly limited, but is preferably 0 to 4, and more preferably 1 to 3. Examples of the acid contained in the acid solution include inorganic acids, sulfonic acids, and carboxylic acids. Examples of inorganic acids include sulfuric acid, nitric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, phosphoric acid, and boric acid. Examples of sulfonic acids include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid. Examples of carboxylic acids include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid. Among these, hydrochloric acid or sulfuric acid is particularly preferred.
The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably, for example, 5° C. to 100° C., and more preferably, 20° C. to 90° C. The immersion time in the acid solution in the acid treatment is not particularly limited, but is, for example, preferably, 5 minutes to 120 minutes, and more preferably, 10 minutes to 60 minutes. The amount of the acid solution used in the acid treatment is not particularly limited, but is, for example, preferably, 100 mass % to 100,000 mass % and more preferably, 1,000 mass % to 10,000 mass % relative to the absolute dry mass of the fiber raw material.

(Fibrillation process)
By subjecting the ionic group-introduced fibers to defibration treatment in a defibration treatment step, fine fibrous cellulose can be obtained.
In the defibration treatment step, for example, a defibration treatment device can be used. The defibration treatment device is not particularly limited, but examples that can be used include a high-speed defibrator, a grinder (stone mill-type grinder), a high-pressure homogenizer, an ultra-high-pressure homogenizer, a high-pressure collision grinder, a ball mill, a bead mill, a disk-type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater. Among the above defibration treatment devices, it is more preferable to use a high-speed defibrator, a high-pressure homogenizer, or an ultra-high-pressure homogenizer, which are less affected by the grinding media and have less risk of contamination.

In the defibration process, it is preferable to dilute the ionic group-introduced fibers with a dispersion medium to form a slurry. The dispersion medium can be one or more selected from water and organic solvents such as polar organic solvents. Polar organic solvents are not particularly limited, but examples of preferred solvents include alcohols, polyhydric alcohols, ketones, ethers, esters, and aprotic polar solvents. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, and isobutyl alcohol. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, and glycerin. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, and propylene glycol monomethyl ether. Examples of esters include ethyl acetate and butyl acetate. Aprotic polar solvents include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP), etc.

The solid content concentration of the fine fibrous cellulose during the defibration treatment can be appropriately set.
The slurry obtained by dispersing the phosphorus oxo acid group-introduced fibers in a dispersion medium may contain solid components other than the phosphorus oxo acid group-introduced fibers, such as urea having hydrogen bonding properties.

[Pulp fiber]
In the present invention, the fibrous cellulose may contain, in addition to the above-mentioned fine fibrous cellulose, pulp fibers having a fiber width of more than 1,000 nm.
The pulp fibers may have, for example, at least one of an ionic group and a nonionic group. From the viewpoint of improving the dispersibility of the pulp fibers in the dispersion medium, it is more preferable that the pulp fibers have an ionic group. The ionic group may include, for example, either one or both of an anionic group and a cationic group. Furthermore, the nonionic group may include, for example, an alkyl group and an acyl group. In this embodiment, it is particularly preferable that the ionic group include an anionic group.
The method for introducing anionic groups into pulp fibers is to carry out an ionic group introduction step in the method for producing fine fibrous cellulose, and the pulp fibers can be produced in the same manner except that the defibration treatment step is not included.

From the viewpoint of obtaining good granulation properties, the fiber width and average fiber width of the pulp fibers are preferably 3 μm or more, more preferably 10 μm or more, even more preferably 25 μm or more, and are preferably 100 μm or less, more preferably 50 μm or less, even more preferably 35 μm or less.
The fiber width and average fiber width of the pulp fibers are measured by the method described in the Examples.

From the standpoint of viscosity of the binder solution and economic efficiency, the pulp fiber content in the fibrous cellulose is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less; it may be 0% by mass, but is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more.

<Water-soluble polymer>
The granulated product of the present invention contains a water-soluble polymer. In the present invention, the water-soluble polymer refers to a water-soluble polymer other than the above-mentioned fibrous cellulose.
The water-soluble polymer refers to a polymer compound having a solubility of 1 g or more in 100 g of water at any liquid temperature between 0 and 100° C. The polymer compound refers to a compound having a weight-average molecular weight of 1,000 or more, preferably 5,000 or more.

The water-soluble polymer is not particularly limited, but examples thereof include polysaccharides and derivatives thereof, water-soluble proteins, and water-soluble synthetic polymers.
Examples of polysaccharides and derivatives thereof include cellulose derivatives such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose; resin polysaccharides such as gum arabic, torrant gum, and karaya gum; seed polysaccharides such as tamarind gum, guar gum, tara gum, and locust bean gum; seaweed polysaccharides such as alginates, propylene glycol alginate, carrageenan, furcellanus, and agar; plant polysaccharides such as high methoxy pectin and low methoxy pectin; starches such as raw starch, dextrin British gum, oxidized starch, and etherified or esterified starch; microbially produced polysaccharides such as xanthan gum, pullulan, and glucan; aminopolysaccharides such as chitin and chitosan; and mucopolysaccharides such as chondroitin sulfate and hyaluronic acid.
Examples of water-soluble proteins include casein, gelatin, and albumin.
Examples of water-soluble synthetic polymers include polyvinyl alcohol, polyvinylpyrrolidone, alkylene oxides such as polyethylene oxide, and polyalkylene glycols such as polyethylene glycol.

Among these, at least one selected from the group consisting of starches, cellulose derivatives, gelatin, polyvinyl alcohol and its derivatives, polyacrylamide, polyacrylic acid and its salts, polyacrylic acid copolymers, polyvinylpyrrolidone, and polyethylene glycol is preferred, and starches, cellulose derivatives, polyvinyl alcohol and its derivatives, polyacrylamide, polyacrylic acid and its salts are more preferred.
The water-soluble polymer may be used alone or in combination of two or more kinds.

When using a water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23°C (hereinafter, a water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23°C will also be referred to as a "high-viscosity water-soluble polymer") as the water-soluble polymer, it is preferable to use in combination a water-soluble polymer having a viscosity of 100 mPa·s or less in a 1% by mass aqueous solution at 23°C (hereinafter, a water-soluble polymer having a viscosity of 100 mPa·s or less in a 1% by mass aqueous solution at 23°C will also be referred to as a "low-viscosity water-soluble polymer"), from the viewpoint of reducing the viscosity of the binder solution.
The viscosity of a 1% by mass aqueous solution of the high-viscosity water-soluble polymer at 23°C is 1,000 mPa·s or more, and from the viewpoint of improving the particle hardness of the granules, it is preferably 1,300 mPa·s or more, more preferably 1,700 mPa·s or more, and even more preferably 2,000 mPa·s or more, and from the viewpoint of handleability, it is preferably 100,000 mPa·s or less, more preferably 60,000 mPa·s or less, and even more preferably 10,000 mPa·s or less.
The viscosity of a 1% by mass aqueous solution of the low-viscosity water-soluble polymer at 23° C. is 100 mPa s or less, preferably 70 mPa s or less, more preferably 40 mPa s or less, and even more preferably 20 mPa s or less. The lower limit is not particularly limited, but from the viewpoint of availability, it is preferably 0.01 mPa s or more.
The viscosity is measured using a Brookfield viscometer at 23°C and a rotation speed of 3 rpm after stirring an aqueous solution adjusted to a solids concentration of 1% by mass with a disperser for 5 minutes at 1,500 rpm and then allowing the solution to stand for 24 hours in an environment of 23°C and a relative humidity of 50% before measurement. More specifically, a Brookfield analog viscometer, such as the T-LVT, can be used. Measurement is performed under conditions such as a liquid temperature of 23°C and a rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement is taken as the viscosity of the dispersion. The aqueous solution may contain the water-soluble polymer completely dissolved or dispersed.

Examples of high-viscosity water-soluble polymers include carboxymethyl cellulose, hydroxyethyl cellulose, oxidized starch, polyacrylamide, guar gum, and polyacrylic acid. Among these, from the viewpoint of particle hardness of the granulated product, carboxymethyl cellulose, oxidized starch, and polyacrylamide are preferred, and carboxymethyl cellulose is more preferred.
Examples of low-viscosity water-soluble polymers include polyacrylates and alginates. Among these, polyacrylates are preferred, and sodium polyacrylate is more preferred, from the viewpoint of reducing the viscosity of the binder solution and the particle hardness of the granulated product.
Examples of polyacrylates include alkali metal salts of polyacrylic acid such as sodium polyacrylate and potassium polyacrylate, with sodium polyacrylate being preferred.
Examples of alginates include sodium alginate, potassium alginate, and ammonium alginate, with sodium alginate being preferred.

When a high-viscosity water-soluble polymer and a low-viscosity water-soluble polymer are used in combination, the blending ratio of the high-viscosity water-soluble polymer to the low-viscosity water-soluble polymer (high-viscosity water-soluble polymer/low-viscosity water-soluble polymer, mass ratio) is preferably 1/2 or more, more preferably 1/1 or more, even more preferably 1.5/1 or more, from the viewpoint of reducing the viscosity of the binder solution and the particle hardness of the granulated product, and is preferably 20/1 or less, more preferably 10/1 or less, even more preferably 5/1 or less.

<Binder component and binder solution>
In the present invention, fibrous cellulose and a water-soluble polymer are used as binder components (granulating agents) for a powder selected from the group consisting of inorganic powders and organic powders, and the powder is granulated.
The total solid content of the fibrous cellulose and the water-soluble polymer per 100 parts by mass of the powder is, from the viewpoints of granulation ability and particle hardness of the granulated product, preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 1 part by mass or less.

The blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) is preferably 1/10 or more, more preferably 1/3 or more, and even more preferably 1/1 or more, from the viewpoints of the viscosity of the binder solution and the particle hardness of the granulated product, and is preferably 1,000/1 or less, more preferably 100/1 or less, even more preferably 10/1 or less, and even more preferably 5/1 or less.

The binder component is preferably applied in a liquid state, more preferably in an aqueous dispersion state. In the binder solution containing the binder component, the fibrous cellulose and the water-soluble polymer, which are the binder components, are preferably at least partially dissolved, and may be partially dispersed.
From the viewpoints of uniform mixing with the powder and ease of handling during production, the viscosity of the binder solution during use is preferably 0.1 mPa s or more, more preferably 1 mPa s or more, even more preferably 5 mPa s or more, and is preferably 4,000 mPa or less, more preferably 2,000 mPa s or less, even more preferably 1,500 mPa s or less, still more preferably 1,000 mPa s or less, and particularly preferably 950 mPa s or less.
The concentration of the binder solution during use is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, from the viewpoint of facilitating drying, and is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and even more preferably 3.0% by mass or less, from the viewpoint of uniform application and ease of handling.

The solvent for the binder solution is preferably one whose main component is water, and may contain an organic solvent in addition to water. Examples of the organic solvent include the polar organic solvents listed in the defibration process. The water content in the solvent for the aqueous dispersion is 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

<Powder>
The granulated product of the present invention is obtained by granulating at least one powder selected from the group consisting of inorganic powders and organic powders with the binder component described above.
[Inorganic powder]
The inorganic powder used in the present invention is not particularly limited, and may be appropriately selected depending on the intended use of the granulated product.
When the granulated material is used as a fertilizer, the inorganic powder is preferably an inorganic powder containing at least one element selected from the group consisting of nitrogen, phosphoric acid, potassium, lime, silicic acid, magnesium, manganese, and boron oxide (B ₂ O ₃ ) as a main component.
When the granulated material is used as a nutritional component for plants, examples of suitable additives include sulfur oxide (SO ₂ ), iron, copper, zinc, and molybdenum.
Other examples of inorganic powders include dolomite (main components of which are magnesium carbonate and calcium carbonate) and sulfur.

_Examples of inorganic powders containing nitrogen as _a main component include ammonium sulfate (( _NH4 ) _2SO4 ), ammonium chloride ( _NH4Cl ), ammonium nitrate ( _NH4NO3 ), sodium nitrate ( _NaNO3 ), and calcium carbonate ( _CaCN2 , CaO). Here, calcium carbonate is made from, for example, coke obtained from coal and quicklime, and sodium nitrate is made from, for example, Chilean saltpeter.
Examples of inorganic powders containing phosphoric acid as a main component include superphosphate ( _{a mixture of Ca(H2PO4)2.H2O and CaSO4} ), triple superphosphate ( _{Ca(H2PO4)2.H2O), fused phosphate fertilizer, calcined phosphate fertilizer (Ca5Na2(PO4)4 ) , and ammonium phosphate . Here ,} superphosphate is a mixture of monocalcium phosphate produced by reacting rock phosphate with sulfuric acid and calcium sulfate (gypsum) _. Triple superphosphate is produced by reacting rock phosphate with phosphoric acid to produce monocalcium phosphate. Ammonium phosphate is produced by reacting ammonium with phosphoric acid, which is produced by reacting rock phosphate with sulfuric acid. Fused phosphate fertilizer is produced by heating and melting rock phosphate and serpentine in an electric furnace. Fluorapatite in the rock phosphate is decomposed by heating and removing fluorine to produce an organic phosphate fertilizer. Furthermore, calcined phosphate fertilizer is produced by calcining phosphate rock with sodium carbonate and phosphoric acid at a high temperature that does not melt the rock, destroying the apatite structure and removing fluorine, resulting in phosphate fertilizer.
Examples of inorganic powders containing potassium as a main component include potassium chloride (KCl), potassium sulfate ( _K2SO4 ), and potassium _silicate . Potassium chloride can be obtained by methods such as beneficiating or recrystallizing ores (such as sylvinite or carnallitite), or by concentrating and fractionally crystallizing natural brine. Potassium sulfate can be obtained by reacting potassium chloride with sulfuric acid. Potassium silicate can be obtained by mixing fly ash, potassium hydroxide, and magnesium hydroxide, granulating the mixture, and then firing the mixture.

The inorganic powder containing lime as a main component is an inorganic powder containing calcium as a main component, and examples thereof include quicklime, slaked lime, lime carbonate, and lime nitrogen.
Furthermore, examples of inorganic powders containing silicic acid as a main component include slag, and specific examples include pig iron slag, ordinary steel slag, stainless steel slag, and silico-manganese slag.
Examples of inorganic powders containing magnesium as a main component include dolomite (magnesium lime), kieserite, etc. Magnesium chloride, magnesium sulfate, magnesium nitrate, etc. may also be used.
Examples of inorganic powders containing manganese as a main component include manganese sulfate, manganese carbonate, etc. Manganese slag may also be used.
An example of an inorganic powder containing boron as a main component is borax.
The inorganic powder may be used alone or in combination of two or more. When the granules are used as a fertilizer, the granules may be a compound fertilizer containing two or more of the three elements nitrogen (N), phosphorus (P), and potassium (K), or may be a trace element compound fertilizer containing both manganese and boron.
When the granulated material is used as a fertilizer, it may contain an organic powder such as urea in addition to the inorganic powder described above. From the viewpoint of granulation properties, the amount of the inorganic powder relative to the total of the inorganic powder and the organic powder is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and may even be 100% by mass.

When the granulated material is used as a soil conditioner, examples of inorganic powders include perlite, vermiculite, zeolite, bentonite, and calcined diatomaceous earth.

When the granulated material is used as a snow-melting agent, examples of the inorganic powder include calcium chloride, sodium chloride, magnesium chloride, and carbon black.
When the granulated material is used as a snow-melting agent, urea or a metal acetate such as calcium acetate, magnesium acetate or potassium acetate may be used in addition to the inorganic powders mentioned above.

When the granulated material is used for applications such as tablets in foods, cosmetics, and pharmaceuticals, examples of inorganic powders include calcium carbonate, dibasic _calcium phosphate (calcium hydrogen phosphate and its dihydrate, _CaHPO4.2H2O ), tribasic calcium phosphate (calcium phosphate, _Ca3 ( _PO4 ) ₂ ), calcium sulfate, and kaolin.

[Organic powder]
The organic powder may be appropriately selected from organic powders used in foods, cosmetics, medicines, and fertilizers.
For example, examples of organic powders used as excipients for pharmaceuticals include microcrystalline cellulose, powdered cellulose, dextrates, dextrin, glucose additives, fructose, lactitol, anhydrous lactose, lactose, maltitol, maltodextrin, maltose, mannitol, sorbitol, starch, corn starch, potato starch, pregelatinized starch, modified pregelatinized starch, tapioca starch, wheat starch, refined sucrose, and compressible sugar.

The at least one powder selected from the group consisting of inorganic powders and organic powders may be used alone or in combination of two or more. Further, powders having different particle sizes may be mixed and used depending on the application.
The powder is preferably an inorganic powder, more preferably a water-insoluble or poorly water-soluble inorganic powder, from the viewpoint of particle hardness, etc. Here, water-insoluble means that the solubility in 100 g of water at 25° C. is 0.1 g or less, and poorly water-soluble means that the solubility in 100 g of water at 25° C. is more than 0.1 g but 0.5 g or less.

The particle size of the powder is not particularly limited, but is preferably 12 mesh or larger. Here, particle size refers to the largest mesh of a sieve through which 50% or more by mass of the particles pass. The particle size of the inorganic powder is more preferably 16 mesh or larger, even more preferably 30 mesh or larger, even more preferably 50 mesh or larger, and particularly preferably 83 mesh or larger. It is also preferably 500 mesh or smaller, more preferably 330 mesh or smaller, even more preferably 200 mesh or smaller, and even more preferably 149 mesh or smaller.
The relationship between mesh and opening size is determined in accordance with JIS Z 8801-1:2006, with 12 mesh corresponding to an opening size of 1.40 mm, 16 mesh corresponding to an opening size of 1 mm, 30 mesh corresponding to an opening size of 550 μm, 50 mesh corresponding to an opening size of 300 μm, 83 mesh corresponding to an opening size of 180 μm, 500 mesh corresponding to an opening size of 25 μm, 330 mesh corresponding to an opening size of 45 μm, 200 mesh corresponding to an opening size of 75 μm, and 149 mesh corresponding to an opening size of 100 μm.

<Characteristics of granules>
The granulated product of the present invention is obtained by granulating at least one powder selected from the group consisting of inorganic powders and organic powders with fibrous cellulose containing fine fibrous cellulose and a binder component containing a water-soluble polymer.
In the present invention, the granules may contain other components in addition to the fibrous cellulose, the water-soluble polymer, and the powder.

The particle hardness of the granulated material varies depending on the intended use of the granulated material, and may be appropriately selected depending on the intended use.
When the granules are used as a fertilizer, from the viewpoint of durability in storage and mechanical spraying, the weight is preferably 450 g or more, more preferably 500 g or more, even more preferably 550 g or more, still more preferably 700 g or more, still more preferably 800 g or more, and still more preferably 900 g or more, and from the viewpoint of imparting appropriate disintegrability in water, the weight is preferably 5,000 g or less, more preferably 3,000 g or less, even more preferably 2,000 g or less, still more preferably 1,500 g or less, and still more preferably 1,200 g or less.
When the granulated product is used for pharmaceutical purposes, from the viewpoints of storage stability, suppressing disintegration in the oral cavity, and imparting appropriate disintegrability in water, the weight is preferably 1,000 g or more, more preferably 3,000 g or more, and even more preferably 5,000 g or more, and is preferably 30,000 g or less, more preferably 20,000 g or less, and even more preferably 16,000 g or less.
The particle hardness of the granulated product is measured by the method described in the Examples.

The average particle size of the granulated product is not particularly limited and may be selected appropriately depending on the application. From the viewpoint of ease of granulation, however, it is preferably 1 mm or more, and preferably 10 mm or less, more preferably 8 mm or less, even more preferably 6 mm or less, and even more preferably 4 mm or less.
The average particle size is measured by a sieving method, using a Rotap type automatic sieve using a standard sieve conforming to JIS Z 8801:2006, stacking the samples in order of smallest mesh size, and weighing the samples remaining on each sieve. The particle size at which the cumulative 50% of the samples are removed is taken as the average particle size.
The granulated product obtained by the present invention may be sieved to remove fine particles and coarse particles.

In the present invention, the granulated product can be used in a variety of applications, such as fertilizers, soil conditioners, snow-melting agents, anti-skid agents, paving materials, foods, medicines, cosmetics, and the like.
Among these, the granules of the present invention are suitably used as fertilizers, soil improvers and snow melting agents, from the viewpoint of the particle hardness of the granules and their disintegratability in water.

[Method of manufacturing granulated product]
The method for producing the granulated product (granulation method) of the present invention is not particularly limited, but preferably includes a step of mixing at least one powder selected from the group consisting of inorganic powders and organic powders with an aqueous dispersion containing fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less and a water-soluble polymer, and granulating the mixture.
For example, a granulation method may be appropriately selected from stirring granulation, rolling granulation, extrusion granulation, etc. Among these, rolling granulation is preferred from the viewpoint of obtaining granules that have disintegratability in water when used and from the viewpoint of production costs.
The method for producing a granulated product of the present invention preferably includes a step of mixing a powder with an aqueous dispersion (binder solution) containing fibrous cellulose, including fine fibrous cellulose having a fiber width of 1,000 nm or less, and a water-soluble polymer, to perform granulation, and more preferably includes a step of tumbling and granulating the powder using a binder solution containing fibrous cellulose and a water-soluble polymer.
The powder and binder components used here are as described above, and the preferred embodiments are also the same.

The amount of binder solution applied to the powder is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, relative to 100 parts by mass of powder, from the viewpoint of applying the binder solution uniformly to the powder to allow granulation to proceed uniformly, and from the viewpoint of enabling granulation in a short time, and is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 20 parts by mass or less.
Therefore, it is preferable to apply the binder solution to the powder by appropriately adjusting the concentration of the binder solution so that the amount of the binder solution applied to the powder falls within the desired range.

Granules are obtained by granulating powder using fibrous cellulose and a water-soluble polymer as binder components, and it is preferable to apply the fibrous cellulose and the water-soluble polymer as an aqueous dispersion (binder solution) to the powder. Granulation methods that can be used include tumbling granulation, fluidized bed granulation, agitation granulation, compression granulation, extrusion granulation, and crushing granulation, with tumbling granulation being preferred. For fertilizer granules, spherical shapes are generally preferred over irregular shapes or those with sharp corners, so tumbling granulation is particularly suitable.
The tumbling granulation method may be appropriately selected from known methods, such as the Roche method, the drum method, etc. The tumbling granulator may be a cement mixer, a drum mixer, a pan-type granulator, etc.
The method for applying the binder solution is not particularly limited, and the powder and binder solution may be kneaded in advance using a mixer or kneader and then placed in a granulator. However, from the viewpoint of applying the binder solution uniformly to the entire powder and allowing granulation to proceed uniformly, it is preferable to apply the binder solution in the form of small droplets, such as by spraying.
The granulation time is not particularly limited, but from the viewpoint of obtaining a granulated product having the desired particle hardness, producing a granulated product in a short time, and improving production efficiency, it is preferably 1 minute or more, more preferably 2 minutes or more, even more preferably 4 minutes or more, and is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 10 minutes or less.
In order to remove excess moisture from the granulated material, the granulated material may be heated during granulation, or a gas may be blown into the granulated material during granulation.

In the present invention, the granules obtained by tumbling granulation may be classified by sieving or other suitable means. This allows for the removal of small particles and coarse particles, resulting in granules having the desired particle size.

[Granulating agent for powder]
The granulating agent for powders of the present invention (also simply referred to as "granulating agent") contains fibrous cellulose containing fine fibrous cellulose having a fiber width of 1,000 nm or less, and a water-soluble polymer.
Examples of the fibrous cellulose, fine fibrous cellulose and water-soluble polymer include the fibrous cellulose, fine fibrous cellulose and water-soluble polymers mentioned above, and the preferred ranges are also the same.
Furthermore, as described above, when a high-viscosity water-soluble polymer having a viscosity of 1,000 mPa s or more in a 1% by mass aqueous solution at 23° C. is used as the water-soluble polymer, it is preferable to use it in combination with a low-viscosity water-soluble polymer having a viscosity of 100 mPa s or less in a 1% by mass aqueous solution at 23° C. The preferred embodiments of the high-viscosity water-soluble polymer and the low-viscosity water-soluble polymer, and the preferred embodiments regarding their combined use, are as described above.
The preferred blend ratio of the fibrous cellulose and the water-soluble polymer in the granulating agent for powder is also as described above.
The granulating agent for powders may be in any form, such as powder, wet powder, or liquid, and when used, it is preferable to prepare it into a slurry by dissolving or dispersing it in water to form a binder solution before use.

The following examples and comparative examples further illustrate the features of the present invention. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Production Example 1]
[Preparation of phosphate group-introduced pulp fiber (phosphorylated pulp)]
The raw pulp used was softwood kraft pulp (solids content 93% by mass, basis weight 245 g/ ^m² sheet, disintegrated, Canadian Standard Freeness (CSF) of 700 mL as measured in accordance with JIS P 8121:2012) manufactured by Oji Paper Co., Ltd. This raw pulp was subjected to a phosphorus oxo-oxidation treatment as follows: First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea was added to 100 parts by mass (bone dry mass) of the raw pulp to adjust the composition to 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. The resulting chemical-impregnated pulp was then heated in a hot air dryer at 165°C for 250 seconds to introduce phosphate groups into the cellulose in the pulp, thereby obtaining phosphate-introduced pulp fibers (phosphated pulp).

The resulting phosphorylated pulp was then washed. The washing process consisted of pouring 10 L of ion-exchanged water into 100 g (bone dry mass) of phosphorylated pulp to obtain a pulp dispersion. The pulp was stirred to uniformly disperse the pulp, and then repeatedly filtered and dehydrated. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.
Next, the washed phosphorylated pulp was neutralized as follows: First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1 N aqueous solution of sodium hydroxide was added little by little while stirring to obtain a phosphorylated pulp slurry having a pH of 12 to 13. Next, the phosphorylated pulp slurry was dehydrated to obtain a neutralized phosphorylated pulp.

Next, the neutralized phosphorylated pulp was subjected to the above-mentioned washing treatment, and ion-exchanged water was added to obtain a phosphorylated pulp dispersion (dispersion (1)) having a solid content concentration of 2% by mass.
Infrared absorption spectroscopy of the phosphorylated pulp using FT-IR revealed absorption at around 1,230 cm ⁻¹ due to phosphate groups, confirming the addition of phosphate groups to the pulp. The phosphorylated pulp was analyzed using an X-ray diffractometer, revealing typical peaks at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals. The amount of phosphate groups (amount of first dissociated acid) measured by the measurement method described below was 1.45 mmol/g. The total amount of dissociated acid was 2.45 mmol/g. The fiber width measured by the measurement method described below was approximately 30 μm.

[Production Example 2]
[Preparation of phosphate group-introduced fine fibrous cellulose (phosphorylated CNF)]
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry with a solids concentration of 2% by mass. This slurry was treated twice at a pressure of 200 MPa using a wet pulverizer (Starburst, manufactured by Sugino Machine Corporation) to obtain a dispersion of phosphorylated fine fibrous cellulose (phosphorylated CNF) (Dispersion (2)). X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystal structure. The amount of phosphoric acid groups (amount of first dissociated acid) measured by the measurement method described below was 1.45 mmol/g. The fiber width measured by the measurement method described below was 3 to 5 nm.

[Production Example 3]
[Preparation of Phosphite Group-Introduced Fine Fibrous Cellulose (Phosphite-Containing CNF)]
Pulp fibers having phosphorous acid groups introduced therein (phosphited pulp) were obtained by the same procedure as in [Production Example 1], except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate.
The infrared absorption spectrum of the obtained phosphorous-containing pulp was measured using FT-IR. As a result, absorption due to P=O of the phosphonic acid group, which is a tautomer of the phosphorous acid group, was observed around 1,210 cm ^-1 , confirming that the phosphorous acid group (phosphonic acid group) had been added to the pulp. Furthermore, when the obtained phosphorous-containing pulp was analyzed using an X-ray diffractometer, typical peaks were observed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting phosphite-modified pulp was subjected to a micronization process in the same manner as in Production Example 2 to obtain a dispersion of phosphite-modified fine fibrous cellulose (phosphite-modified CNF) (Dispersion (3)). X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the amount of (phosphite) groups (amount of first dissociated acid) measured using the measurement method described below was 1.51 mmol/g. The total amount of dissociated acid was 1.54 mmol/g. The fiber width measured using the measurement method described below was 3 to 5 nm.

[Production Example 4]
[Preparation of carboxyl group-introduced fine fibrous cellulose (TEMPO-oxidized CNF)]
Softwood kraft pulp (undried) manufactured by Oji Paper Co., Ltd. was used as the raw material pulp. This raw material pulp was subjected to an alkaline TEMPO oxidation treatment as follows. First, 100 parts by mass (bone dry mass) of the raw material pulp, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), and 10 parts by mass of sodium bromide were dispersed in 10,000 parts by mass of water. Next, a 13% by mass aqueous solution of sodium hypochlorite was added to 1.0 g of pulp to give a concentration of 3.8 mmol to initiate the reaction. During the reaction, a 0.5 M aqueous solution of sodium hydroxide was added dropwise to maintain the pH at 10 to 10.5, and the reaction was considered complete when no further change in pH was observed. Carboxy groups were introduced into the pulp fibers by the TEMPO oxidation treatment.

The resulting TEMPO-oxidized pulp was then washed. The washing process involved dehydrating the pulp slurry after TEMPO oxidation to obtain a dehydrated sheet, pouring 5,000 parts by mass of ion-exchanged water into it, stirring to uniformly disperse it, and then repeatedly filtering and dehydrating it. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.

The resulting TEMPO-oxidized pulp was analyzed using an X-ray diffractometer. Typical peaks were observed at two positions, near 2θ = 14° to 17° and near 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting TEMPO-oxidized pulp was subjected to a micronization process in the same manner as in Production Example 2 to obtain a dispersion of carboxy-introduced fine fibrous cellulose (TEMPO-oxidized CNF) (Dispersion (4)). X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the amount of carboxy groups measured by the measurement method described below was 1.30 mmol/g. The fiber width measured by the measurement method described below was 3 to 5 nm.

[Production Example 5]
[Preparation of unmodified pulp fibers]
Softwood kraft pulp was disintegrated to obtain unmodified pulp fibers. The unmodified pulp fibers were diluted with ion-exchanged water to a concentration of 2% by mass to obtain dispersion (5). The fiber width measured by the method described below was approximately 30 μm.

[Production Example 6]
[Preparation of unmodified fine fibrous cellulose (unmodified CNF)]
The unmodified pulp fiber obtained in the above [Manufacturing Example 5] was diluted with ion-exchanged water to a concentration of 2% by mass, and then subjected to a refiner treatment to beat (pre-defibrate) until the CSF was 50 mL or less.

The pre-beaten unmodified pulp fibers were subjected to a micronization process in the same manner as in [Production Example 2] to obtain an unmodified fine fibrous cellulose (unmodified CNF) dispersion (Dispersion (6)). When the fiber width was measured using the method described below, fine fibrous cellulose of 1000 nm or less was observed.

[Production Example 7]
[Preparation of carboxyl group-introduced fine fibrous cellulose (hypochlorous acid oxidized CNF)]
A sheet (solids concentration 90% by mass) made from softwood bleached kraft pulp (NBKP) was mixed with a hand mixer (Osaka Chemical Co., Ltd., Labo Millser PLUS) at 20,000 rpm for 15 seconds to produce a fluffy fluffed pulp (solids concentration 90% by mass). Sodium hypochlorite pentahydrate was then added to ion-exchanged water to prepare an aqueous solution with a sodium hypochlorite solids concentration of 22% by mass. 9,000 parts by mass of a 22% by mass aqueous sodium hypochlorite solution was added to 100 parts by mass of the fluffy fluffed pulp, and the mixture was allowed to react for 2 hours while adjusting the temperature in a warm bath to 30°C, yielding a carboxyl-introduced pulp. During the reaction, a 1N aqueous sodium hydroxide solution was added as needed to maintain the pH at 11.

The resulting carboxylated pulp was then washed. The washing process involved pouring ion-exchanged water over the resulting carboxylated pulp to obtain a pulp dispersion. The pulp was then stirred to uniformly disperse the pulp, followed by repeated filtration and dehydration. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.

The amount of carboxy groups in the resulting carboxylated pulp, as measured using the method described below, was 0.70 mmol/g. Furthermore, when the resulting carboxylated pulp was analyzed using an X-ray diffractometer, typical peaks were confirmed at two positions, near 2θ = 14° to 17° and near 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting carboxyl-introduced pulp was subjected to a micronization process in the same manner as in Production Example 2 to obtain a dispersion of carboxyl-introduced fine fibrous cellulose (hypochlorite-oxidized CNF) (Dispersion (7)). X-ray diffraction confirmed that the resulting fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 3 to 5 nm.

[Production Example 8]
[Preparation of carboxyl group-introduced fine fibrous cellulose (maleic acid esterified CNF)]
A sheet (solids concentration 90% by mass) made from bleached softwood kraft pulp (NBKP) was mixed with a hand mixer (Labo Millser PLUS, manufactured by Osaka Chemical Co., Ltd.) at 20,000 rpm for 15 seconds to produce a fluffy fluffing pulp (solids concentration 90% by mass). 100 parts by mass of the fluffy fluffing pulp and 50 parts by mass of maleic anhydride were placed in an autoclave and mixed at 150°C for 2 hours to obtain a carboxyl-introduced pulp.

The resulting carboxylated pulp was then washed. The washing process involved pouring ion-exchanged water over the resulting carboxylated pulp to obtain a pulp dispersion. The pulp was then stirred to uniformly disperse the pulp, followed by repeated filtration and dehydration. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.

The infrared absorption spectrum of the obtained carboxylated pulp was measured using FT-IR. As a result, absorption due to carboxyl groups was observed near 1580 and 1720 cm ^-1 , confirming that maleic acid esterification had occurred. The amount of carboxyl groups in the obtained carboxylated pulp, measured using the measurement method described below, was 1.22 mmol/g. Furthermore, when the carboxylated pulp was analyzed using an X-ray diffractometer, typical peaks were confirmed at two positions, near 2θ = 14° to 17° and near 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting carboxy-introduced pulp was subjected to a micronization treatment in the same manner as in Production Example 2 to obtain a dispersion of carboxy-introduced fine fibrous cellulose (maleic acid esterified CNF) (Dispersion (8)). X-ray diffraction confirmed that the resulting fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 3 to 5 nm.

[Production Example 9]
[Preparation of carboxyl group-introduced fine fibrous cellulose (carboxyethylated CNF)]
The raw pulp used was softwood kraft pulp (solids content 93% by mass, basis weight 245 g/ ^m² sheet, disintegrated, Canadian Standard Freeness (CSF) of 700 mL as measured in accordance with JIS P 8121-2:2012) manufactured by Oji Paper Co., Ltd. A chemical solution consisting of 250 parts by mass of 12N NaOH aqueous solution, 163 parts by mass of 2-chloropropionic acid, and 140 parts by mass of ion-exchanged water (total 553 parts by mass) was added to 100 parts by mass (bone dry mass) of this raw pulp to obtain a chemical-impregnated pulp. The resulting chemical-impregnated pulp was then heated in a hot air dryer at 165°C for 10 minutes to introduce carboxyethyl groups (carboxy groups) into the cellulose in the pulp, yielding a carboxy-introduced pulp.

The resulting carboxylated pulp was then washed. The washing process involved pouring ion-exchanged water over the resulting carboxylated pulp to obtain a pulp dispersion. The pulp was then stirred to uniformly disperse the pulp, followed by repeated filtration and dehydration. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.

Next, the washed carboxylated pulp was neutralized as follows: First, the washed carboxylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous solution of sodium hydroxide was added little by little while stirring to obtain a carboxylated pulp slurry with a pH of 12 to 13. Next, the carboxylated pulp slurry was dehydrated and washed to obtain neutralized carboxylated pulp.

The amount of carboxy groups in the resulting carboxylated pulp, measured using the method described below, was 1.41 mmol/g. Furthermore, when the carboxylated pulp was analyzed using an X-ray diffractometer, typical peaks were confirmed at two positions, near 2θ = 14° to 17° and near 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting carboxy-introduced pulp was subjected to a micronization process in the same manner as in Production Example 2 to obtain a dispersion of carboxy-introduced fine fibrous cellulose (carboxyethylated CNF) (Dispersion (9)). X-ray diffraction confirmed that the resulting fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 3 to 5 nm.

[Production Example 10]
[Preparation of sulfate group-introduced fine fibrous cellulose (sulfated CNF)]
A sulfated pulp was obtained by the same procedure as in [Production Example 2], except that 38 parts by mass of amidosulfuric acid was used instead of ammonium dihydrogen phosphate, except that the heating time in the hot air dryer was 20 minutes.

The obtained sulfated pulp was subjected to infrared absorption spectroscopy using FT-IR. As a result, absorption due to sulfate groups was observed around 1220-1260 cm ^-1 , confirming that sulfate groups had been added to the pulp. Furthermore, when the obtained sulfated pulp was analyzed using an X-ray diffractometer, typical peaks were observed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The obtained sulfated pulp was subjected to a micronization treatment in the same manner as in [Production Example 2] to obtain a dispersion of sulfated CNF (dispersion (10)). X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystal structure. The amount of sulfated groups measured by the measurement method described below was 1.47 mmol/g. The fiber width measured by the measurement method described below was 3 to 5 nm.

[Production Example 11]
[Preparation of sulfoethyl group-introduced fine fibrous cellulose (sulfoethylated CNF)]
The raw pulp used was softwood kraft pulp (solids content 93% by mass, basis weight 245 g/ ^m² sheet, disintegrated, Canadian Standard Freeness (CSF) of 700 mL as measured in accordance with JIS P 8121-2:2012) manufactured by Oji Paper Co., Ltd. A chemical solution consisting of 180 parts by mass of a 2N NaOH aqueous solution and 780 parts by mass of a 25% by mass sodium vinyl sulfonate aqueous solution (total 960 parts by mass) was added to 100 parts by mass (bone dry mass) of this raw pulp to obtain a chemical solution-impregnated pulp. The resulting chemical solution-impregnated pulp was then heated in a hot air dryer at 165°C for 16 minutes to introduce sulfoethyl groups (sulfonic groups) into the cellulose in the pulp, yielding a sulfoethyl group-introduced pulp (sulfonic group-introduced pulp).

The resulting sulfoethyl group-introduced pulp was then washed. The washing process involved pouring ion-exchanged water over the resulting sulfoethyl group-introduced pulp to obtain a pulp dispersion. The pulp was then stirred to uniformly disperse the pulp, and the pulp was then filtered and dehydrated. This process was repeated until the electrical conductivity of the filtrate reached 100 μS/cm or less, marking the end point of the washing process.

The sulfoethyl group content (sulfonic acid content) of the resulting sulfoethyl group-introduced pulp, measured using the method described below, was 1.48 mmol/g. Furthermore, when the sulfoethyl group-introduced pulp was analyzed using an X-ray diffractometer, typical peaks were confirmed at two positions, near 2θ = 14° to 17° and near 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

The resulting sulfoethyl group-introduced pulp was subjected to a micronization treatment in the same manner as in Production Example 2 to obtain a dispersion of sulfoethyl group-introduced fine fibrous cellulose (sulfoethylated CNF) (Dispersion (11)). X-ray diffraction confirmed that the resulting fine fibrous cellulose maintained cellulose type I crystal structure. Furthermore, the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope and found to be 3 to 5 nm.

[Production Example 12]
[Preparation of cationic group-introduced fine fibrous cellulose (cationized CNF)]
As the raw material pulp, softwood kraft pulp (solid content 93% by mass, basis weight 245 g/ ^m2 sheet form, Canadian Standard Freeness (CSF) measured after disintegration in accordance with JIS P 8121-2:2012 of 700 mL) manufactured by Oji Paper Co., Ltd. was used.

To 100 parts by mass (bone dry mass) of this raw pulp, a chemical solution consisting of 180 parts by mass of 1N NaOH aqueous solution and 325 parts by mass of a cationizing agent (Catiomaster G, manufactured by Yokkaichi Synthetic Co., Ltd., glycidyl trimethylammonium chloride, purity 73.1% by mass, moisture content 20.2% by mass) (total 505 parts by mass) was added to obtain chemical-impregnated pulp. The resulting chemical-impregnated pulp was then heated in a hot air dryer at 165°C for 12 minutes to introduce cationic groups into the cellulose in the pulp, yielding cationic group-introduced pulp.

The resulting cation-group-introduced pulp was then washed. The washing process involved pouring ion-exchanged water over the resulting cation-group-introduced pulp to obtain a pulp dispersion. The pulp was then stirred to uniformly disperse the pulp, and the pulp was then filtered and dehydrated. The washing was completed when the electrical conductivity of the filtrate reached 100 μS/cm or less.

The washed cation group-introduced pulp was then neutralized as follows: First, the washed cation group-introduced pulp was diluted with 10 L of ion-exchanged water, and then 1 N hydrochloric acid was added little by little while stirring to obtain a cation group-introduced pulp slurry with a pH of 1 to 2. The cation group-introduced pulp slurry was then dehydrated and washed to obtain neutralized cation group-introduced pulp.

The resulting cationic group-introduced pulp was subjected to trace nitrogen analysis, and the amount of cationic groups calculated using the following formula was 1.45 mmol/g. Furthermore, when the cationic group-introduced pulp was analyzed using an X-ray diffractometer, typical peaks were confirmed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.
(Amount of cationic groups) [mmol/g] = (amount of nitrogen) / 14 × 1000 / (amount of cationic group-introduced pulp tested)

The resulting cationic group-introduced pulp was subjected to a micronization treatment in the same manner as in [Production Example 2] to obtain a dispersion of cationic group-introduced fine fibrous cellulose (cationized CNF) (dispersion (12)).

[Measurement of fiber width]
The fiber widths of the ionic group-introduced pulp and unmodified pulp fibers were measured using a Kajaani fiber length measuring instrument (FS-200 model, manufactured by Kajaani Automation Co., Ltd.).
The fiber width of the fine fibrous cellulose was measured by the following method. The supernatant of the fine fibrous cellulose dispersion was diluted with water to a fine fibrous cellulose concentration of 0.01% by mass to 0.1% by mass, and the diluted solution was dropped onto a hydrophilized carbon grid membrane. After drying, the membrane was stained with uranyl acetate and observed under a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.).

[Measurement of phosphorus oxoacid group content]
The amount of phosphorus oxoacid groups in the fine fibrous cellulose was measured by treating a fibrous cellulose-containing slurry with an ion exchange resin after diluting a dispersion containing the target fine fibrous cellulose with ion exchange water to a content of 0.2 mass% and then titrating the slurry with an alkali.
Treatment with ion exchange resin was carried out by adding 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) to the above fibrous cellulose-containing slurry, shaking for 1 hour, and then pouring the mixture onto a mesh with 90 μm openings to separate the resin from the slurry.
In addition, the alkali titration was performed by adding 10 μL of 0.1 N sodium hydroxide aqueous solution every 5 seconds to the fibrous cellulose-containing slurry after treatment with an ion exchange resin, while measuring the change in the pH value of the slurry. Nitrogen gas was blown into the slurry 15 minutes before the start of the titration. In this neutralization titration, two maximum points of increment (differential value of pH with respect to the amount of alkali added) were observed on the curve plotting the measured pH against the amount of alkali added. Of these, the maximum point of increment obtained first after starting the addition of alkali is called the first endpoint, and the maximum point of increment obtained next is called the second endpoint (Figure 1). The amount of alkali required from the start of the titration to the first endpoint is equal to the amount of first dissociated acid in the slurry used in the titration. Furthermore, the amount of alkali required from the start of the titration to the second endpoint is equal to the total amount of dissociated acid in the slurry used in the titration. The amount of alkali (mmol) required from the start of titration to the first endpoint was divided by the solid content (g) in the slurry to be titrated, and the value was taken as the amount of phosphate groups (mmol/g).
For the phosphorus oxo-oxidized pulp, ion-exchanged water was added to the phosphorus oxo-oxidized pulp to prepare a slurry with a solids concentration of 2% by mass. This slurry was then treated twice in a wet atomization apparatus (Starburst, manufactured by Sugino Machine Co., Ltd.) at a pressure of 200 MPa, and the resulting dispersion was subjected to alkali titration in the same manner as described above.

[Measurement of Carboxy Group Amount]
The amount of carboxy groups in the fine fibrous cellulose and the carboxylated pulp fibers was measured in the same manner as in [Measurement of the amount of phosphorus oxoacid groups], except that 50 μL of 0.1 N aqueous sodium hydroxide solution was added to the fibrous cellulose-containing slurry after treatment with the ion exchange resin once every 30 seconds. The amount of carboxy groups (mmol/g) was calculated by dividing the amount of alkali (mmol) required in the region corresponding to the first region shown in Figure 2 by the solid content (g) in the slurry to be titrated.

[Measurement of sulfonic acid group content and sulfate group content]
The amount of sulfonic acid groups and sulfate groups was measured by wet ashing and ICP emission spectrometry of the sample. Specifically, the fibrous cellulose-containing slurry obtained in Production Example 10 or Production Example 11 was completely dried and then weighed, perchloric acid was added to carbonize it, and concentrated nitric acid was added to oxidize the carbon to carbon dioxide, thereby obtaining a sample solution consisting only of inorganic substances. This sample solution was diluted to an appropriate ratio, and the sulfonate ion or sulfate ion concentration was measured by ICP emission spectrometry. The amount of sulfur atoms contained in the sample solution was divided by the mass of the weighed fibrous cellulose to obtain the amount of sulfonic acid groups or sulfate groups.

[Trace nitrogen analysis]
The amount of cationic groups in the fine fibrous cellulose was measured by drying a fine fibrous cellulose dispersion containing the target fine fibrous cellulose in a vacuum dryer at 40°C for 24 hours to an absolutely dry state, and then using a TN-110 trace total nitrogen analyzer manufactured by Mitsubishi Chemical Analic Corporation. Note that ionic nitrogen was removed during the neutralization and washing processes of the cationized pulp. The amount of cationic groups introduced per unit mass of the fine fibrous cellulose (mmol/g) was calculated by dividing the nitrogen content (g/g) per unit mass of the fine fibrous cellulose obtained by trace nitrogen analysis by the atomic weight of nitrogen.

[Example 1]
Dispersion liquid (2), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Corporation), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (1).
Lime powder manufactured by Oji Wood & Green Co., Ltd. (hereinafter simply referred to as "lime powder") was used as the raw inorganic powder. 10 parts by mass of binder solution (1) was added to 100 parts by mass of lime powder, and the mixture was rotated in a cement mixer for 2 minutes to granulate. The granules were dried in a hot air dryer at 100°C for 30 minutes. The resulting granules were sieved to obtain granules with a particle size of 1 to 4 mm.

[Example 2]
Dispersion liquid (2), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass, to prepare binder solution (2). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (2).

[Example 3]
Dispersion liquid (2), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (3). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (3).

[Example 4]
Dispersion liquid (2), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (4). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (4).

[Example 5]
Dispersion liquid (2), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (5). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (5).

[Example 6]
Dispersion liquid (3), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (6). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (6).

[Example 7]
Dispersion liquid (3), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass, to prepare binder solution (7). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (7).

[Example 8]
Dispersion liquid (3), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (8). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (8).

[Example 9]
Dispersion liquid (3), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (9). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (9).

[Example 10]
Dispersion liquid (3), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (10). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (10).

[Example 11]
Dispersion liquid (4), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (11). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (11).

[Example 12]
Dispersion liquid (4), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass, to prepare binder solution (12). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (12).

[Example 13]
Dispersion liquid (4), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (13). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (13).

[Example 14]
Dispersion liquid (4), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (14). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (14).

[Example 15]
A binder solution (15) was prepared by mixing dispersion (4), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (15).

[Example 16]
A binder solution (16) was prepared by mixing dispersion (6), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (16).

[Example 17]
A binder solution (17) was prepared by mixing dispersion (6), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (17).

[Example 18]
Dispersion liquid (6), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (18). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (18).

[Example 19]
Dispersion liquid (6), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (19). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (19).

[Example 20]
A binder solution (20) was prepared by mixing dispersion (6), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (20).

[Example 21]
Dispersion (1) was mixed so that the fibrous cellulose content as a solid content was 0.32% by mass, dispersion (2) was mixed so that the fibrous cellulose content as a solid content was 0.08% by mass, and an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.) was mixed so that the carboxymethyl cellulose (CMC) content as a solid content was 0.4% by mass, and ion-exchanged water was added appropriately to prepare binder solution (21). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (21).

[Example 22]
Dispersion (5) was mixed so that the fibrous cellulose content as a solid content was 0.32% by mass, dispersion (6) was mixed so that the fibrous cellulose content as a solid content was 0.08% by mass, and an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.) was mixed so that the carboxymethyl cellulose (CMC) content as a solid content was 0.4% by mass, and ion-exchanged water was added appropriately to prepare binder solution (22). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (22).

[Example 23]
Dispersion liquid (2), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Corporation), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (1).
D-sorbitol powder (hereinafter simply referred to as "sorbitol powder") manufactured by Kanto Chemical Co., Inc. was used as the raw organic powder. 10 parts by mass of binder solution (1) was added to 100 parts by mass of the sorbitol powder, and the mixture was rotated in a cement mixer for 2 minutes to granulate. The granulated product was dried in a hot air dryer at 100°C for 30 minutes. The resulting granulated product was sieved to obtain granules with a particle size of 1 to 4 mm.

[Example 24]
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 23, except that the binder solution (1) was changed to the binder solution (2).

[Example 25]
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 23, except that the binder solution (1) was changed to the binder solution (3).

[Example 26]
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 23, except that the binder solution (1) was changed to the binder solution (4).

[Example 27]
A binder solution (23) was prepared by mixing dispersion (2), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Corporation), an aqueous solution of sodium polyacrylate (Aron A-20UN, manufactured by Toagosei Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass, the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, and the content of sodium polyacrylate (SPA) as a solid content was 0.1% by mass.
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 1, except that the binder solution (1) was changed to the binder solution (23).

[Example 28]
A binder solution (24) was prepared by mixing dispersion (2), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Corporation), an aqueous solution of sodium polyacrylate (Aron A-20UN, manufactured by Toagosei Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass, the content of carboxymethyl cellulose (CMC) as a solid content was 0.33% by mass, and the content of sodium polyacrylate (SPA) as a solid content was 0.17% by mass.
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 1, except that the binder solution (1) was changed to the binder solution (24).

[Example 101]
A binder solution (101) was prepared by mixing dispersion (7), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (101).

[Example 102]
A binder solution (102) was prepared by mixing dispersion (7), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (102).

[Example 103]
Dispersion liquid (7), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (103). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (103).

[Example 104]
A binder solution (104) was prepared by mixing dispersion (7), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (104).

[Example 105]
A binder solution (105) was prepared by mixing dispersion (7), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (105).

[Example 106]
A binder solution (106) was prepared by mixing dispersion (8), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (106).

[Example 107]
A binder solution (107) was prepared by mixing dispersion (8), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (107).

[Example 108]
Dispersion liquid (8), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (108). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (108).

[Example 109]
A binder solution (109) was prepared by mixing dispersion (8), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (109).

[Example 110]
A binder solution (110) was prepared by mixing dispersion (8), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (110).

[Example 111]
Dispersion liquid (9), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (111). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (111).

[Example 112]
A binder solution (112) was prepared by mixing dispersion (9), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (112).

[Example 113]
Dispersion liquid (9), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (113). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (113).

[Example 114]
Dispersion liquid (9), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (114). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (114).

[Example 115]
A binder solution (115) was prepared by mixing dispersion (9), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (115).

[Example 116]
A binder solution (116) was prepared by mixing the dispersion (10), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (116).

[Example 117]
A binder solution (117) was prepared by mixing dispersion (10), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (117).

[Example 118]
Dispersion liquid (10), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (118). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (118).

[Example 119]
Dispersion liquid (10), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (119). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (119).

[Example 120]
A binder solution (120) was prepared by mixing the dispersion (10), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (120).

[Example 121]
Dispersion liquid (11), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass, to prepare binder solution (121). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (121).

[Example 122]
A binder solution (122) was prepared by mixing dispersion (11), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (122).

[Example 123]
Dispersion liquid (11), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass, to prepare binder solution (123). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to binder solution (123).

[Example 124]
Dispersion liquid (11), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water were mixed so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass, to prepare binder solution (124). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (124).

[Example 125]
A binder solution (125) was prepared by mixing dispersion (11), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (125).

[Example 126]
A binder solution (126) was prepared by mixing dispersion (12), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (126).

[Example 127]
A binder solution (127) was prepared by mixing dispersion (12), a polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyvinyl alcohol (PVA) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (127).

[Example 128]
A binder solution (128) was prepared by mixing the dispersion liquid (12), an aqueous solution of starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of starch as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (128).

[Example 129]
A binder solution (129) was prepared by mixing dispersion (12), an aqueous solution of polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.1% by mass and the content of polyacrylamide (PAM) as a solid content was 0.2% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (129).

[Example 130]
A binder solution (130) was prepared by mixing dispersion (12), an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), and ion-exchanged water so that the content of fibrous cellulose as a solid content was 0.4% by mass and the content of carboxymethyl cellulose (CMC) as a solid content was 0.4% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that binder solution (1) was changed to the binder solution (130).

[Comparative Example 1]
Carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.) was adjusted with ion-exchanged water so that the content of carboxymethyl cellulose as a solid content was 0.4 mass %, to prepare a binder solution (25).
Granules having a particle size of 1 to 4 mm were obtained in the same manner as in Example 1, except that the binder solution (1) was changed to the binder solution (25).

[Comparative Example 2]
A polyvinyl alcohol solution (PVA-117, manufactured by Kuraray Co., Ltd.) was adjusted with ion-exchanged water so that the polyvinyl alcohol content as a solid content was 0.4 mass%, to prepare a binder solution (26). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (26).

[Comparative Example 3]
Starch (potato starch, Abashiri, manufactured by Okhotsk Abashiri Agricultural Cooperative) was adjusted with ion-exchanged water so that the starch content as a solid content was 0.4 mass%, to prepare a binder solution (27). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (27).

[Comparative Example 4]
Polyacrylamide (Oji Floc A-30791VR, manufactured by Oji Engineering Co., Ltd.) was adjusted with ion-exchanged water so that the polyacrylamide content as a solid content was 0.2 mass%, to prepare a binder solution (28). Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (28).

[Comparative Example 5]
A binder solution (29) was prepared by adjusting an aqueous solution of carboxymethyl cellulose (Terpolymer H, manufactured by Ternite Co., Ltd.), Aron A-20UN, and ion-exchanged water so that the content of carboxymethyl cellulose as a solid content was 0.4% by mass and the content of sodium polyacrylate as a solid content was 0.1% by mass. Granules having a particle size of 1 to 4 mm were obtained in the same manner as in [Example 1], except that the binder solution (1) was changed to the binder solution (29).

[Measurement of particle size of lime powder]
When the particles were sieved using meshes conforming to JIS Z8801-1:2006, the maximum mesh size through which 50% by mass or more of the particles passed was 100 mesh.

[Measurement of particle size of D-sorbitol powder]
When the particles were sieved using meshes conforming to JIS Z8801-1:2006, the maximum mesh size through which 50% by mass or more of the particles passed was 30 mesh.

[Measurement of viscosity of binder solution]
The viscosity of each binder liquid was measured using a Brookfield type viscometer (analog viscometer T-LVT, manufactured by BLOOKFIELD). The measurement conditions were a rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement was taken as the viscosity of the dispersion. The dispersion to be measured was allowed to stand for 24 hours in an environment of 23°C and relative humidity 50% before measurement. The liquid temperature of the dispersion during measurement was 23°C.

[Measurement of particle hardness]
The hardness of 10 granules having a particle size of 1 to 4 mm was measured using a Kiya hardness tester, and the average value was taken as the particle hardness. From the measurement results, the particle hardness was evaluated based on the following criteria.
A: 60g or more B: 40g or more but less than 60g C: 20g or more but less than 40g D: Less than 20g

[Evaluation of underwater disintegration]
Granules of 3 mm or more were selected, 20 granules were arranged on a sieve with 2000 μm openings, and placed in a container of appropriate size. Water was poured into the container until the granules were fully submerged. After standing overnight, the sieve was removed and the number of undisintegrated granules remaining on the sieve was counted. A disintegration rate of 80% or more was judged to be disintegrable.

[result]
As shown in the examples, in Examples 1 to 130, in which inorganic particles (lime) and organic powder (sorbitol) were prepared using fibrous cellulose including fine fibrous cellulose and a binder component containing a water-soluble polymer, granules having disintegratability in water and excellent particle hardness were obtained.
Furthermore, by using both a high-viscosity water-soluble polymer and a low-viscosity water-soluble polymer in combination, it was possible to achieve a low viscosity of the binder solution without reducing the particle hardness.
As shown in Comparative Examples 1 to 5, when no fibrous cellulose including fine fibrous cellulose was contained, sufficient particle hardness could not be obtained in any of the samples.

The present invention provides granulated materials with excellent particle hardness and disintegration properties in water, and is expected to be used in a variety of applications, including fertilizers, soil conditioners, snow-melting agents, anti-slip agents, paving materials, food, pharmaceuticals, and cosmetics.

Claims (12)

The powder is obtained by granulating at least one powder selected from the group consisting of inorganic powders and organic powders with a binder component containing fibrous cellulose containing fine fibrous cellulose having a fiber width of 2 nm or more and 1,000 nm or less and a water-soluble polymer,
The fine fibrous cellulose has anionic groups,
the anionic group is at least one selected from the group consisting of a phosphorus oxoacid group, a substituent derived from a phosphorus oxoacid group, a sulfur oxoacid group, and a substituent derived from a sulfur oxoacid group;
a total solid content of the fibrous cellulose and the water-soluble polymer relative to 100 parts by mass of the powder is 0.001 parts by mass or more and 10 parts by mass or less;
a blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) of 1/10 or more;
A granulated product , wherein the content of the fine fibrous cellulose in the fibrous cellulose is 5% by mass or more . The granules according to claim 1, wherein the fibrous cellulose contains pulp fibers having a fiber width of more than 1,000 nm. 3. The granule according to claim 1 , wherein the amount of anionic groups introduced into the fine fibrous cellulose is 0.50 mmol/g or more and 3.00 mmol/g or less. 4. The granule according to claim 1 , wherein the blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) is 1/10 or more and 1000/1 or less. 5. The granule according to claim 1, wherein the water-soluble polymer comprises a high-viscosity water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23°C, and a low-viscosity water-soluble polymer having a viscosity of 100 mPa· s or less in a 1% by mass aqueous solution at 23°C. 6. The granulated product according to claim 5 , wherein the blending ratio of the high-viscosity water-soluble polymer to the low-viscosity water-soluble polymer (high-viscosity water-soluble polymer/low-viscosity water-soluble polymer, mass ratio) is 1/1 or more and 20/1 or less. 7. The granule according to claim 5 or 6 , wherein the high-viscosity water-soluble polymer is selected from the group consisting of carboxymethyl cellulose, oxidized starch, polyacrylamide, guar gum, and polyacrylic acid. The granule according to any one of claims 5 to 7 , wherein the low-viscosity water-soluble polymer is selected from the group consisting of polyacrylates and alginates. The granulated product according to any one of claims 1 to 8 , wherein the particle size of the powder is 12 mesh or more. The present invention comprises fibrous cellulose containing fine fibrous cellulose having a fiber width of 2 nm or more and 1,000 nm or less, and a water-soluble polymer,
a blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) of 1/10 or more;
The content of the fine fibrous cellulose in the fibrous cellulose is 5% by mass or more,
The fine fibrous cellulose has anionic groups,
the anionic group is at least one selected from the group consisting of a phosphorus oxoacid group, a substituent derived from a phosphorus oxoacid group, a sulfur oxoacid group, and a substituent derived from a sulfur oxoacid group;
Granulating agent for powders. 11. The granulating agent for powders according to claim 10 , wherein the water-soluble polymer comprises a high-viscosity water-soluble polymer having a viscosity of 1,000 mPa·s or more in a 1% by mass aqueous solution at 23 °C, and a low-viscosity water-soluble polymer having a viscosity of 100 mPa·s or less in a 1% by mass aqueous solution at 23°C. The method includes a step of mixing at least one powder selected from the group consisting of inorganic powders and organic powders with an aqueous dispersion containing fibrous cellulose containing fine fibrous cellulose having a fiber width of 2 nm to 1,000 nm and a water-soluble polymer, and granulating the mixture;
The fine fibrous cellulose has anionic groups,
the anionic group is at least one selected from the group consisting of a phosphorus oxoacid group, a substituent derived from a phosphorus oxoacid group, a sulfur oxoacid group, and a substituent derived from a sulfur oxoacid group;
a total solid content of the fibrous cellulose and the water-soluble polymer relative to 100 parts by mass of the powder is 0.001 parts by mass or more and 10 parts by mass or less;
a blending ratio of the water-soluble polymer to the fibrous cellulose (water-soluble polymer/fibrous cellulose) of 1/10 or more;
The content of the fine fibrous cellulose in the fibrous cellulose is 5% by mass or more .
A method for producing granulated material.