WO2021107148A1 - Dispersion liquid - Google Patents

Abstract

The present invention addresses the problem of providing a sheet which has excellent transparency, while being suppressed in curling. The present invention relates to a dispersion liquid which contains a fibrous cellulose that has a fiber width of 1,000 nm or less, while having an ionic substituent, wherein: the content of the fibrous cellulose is 3.0% by mass or more relative to the total mass of the dispersion liquid; and the TI value of the dispersion liquid as calculated under the conditions (a) described below is from 1 to 80,000.　Conditions (a): The viscosity (η1) of the dispersion liquid at a shear rate of 1 sec-1 and the viscosity (η2) of the dispersion liquid at a shear rate of 1,000 sec-1 are measured with use of a rheometer, and the TI value is calculated by the formula described below.　TI value = η1/η2

Description

Dispersion

The present invention relates to a dispersion. Specifically, the present invention relates to a dispersion containing fine fibrous cellulose.

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

When producing fine fibrous cellulose, a slurry containing a cellulose raw material is defibrated (mechanically treated). For example, Patent Document 1 discloses a method for producing fine fibers, which comprises a step of treating a cellulose raw material with an enzyme and a step of defibrating the cellulose raw material after the enzyme treatment. Here, it is studied to sufficiently refine the cellulose raw material and increase the yield of fine fibers by performing enzyme treatment. Further, Patent Document 1 aims to produce fine fibers having a long fiber length and a large aspect ratio.

Further, Patent Document 2 discloses fine fibrous cellulose having an average fiber width of 200 nm or less, a degree of polymerization of 50 or more and 500 or less, and a predetermined polar group. Here, it is studied to obtain fine fibrous cellulose that does not easily form aggregates when mixed with an emulsion resin. In the examples of Patent Document 2, a dispersion having a degree of polymerization of 248 to 454 and a viscosity of 108 to 740 at a concentration of 0.5% is obtained.

International Publication No. 2013/176033 Japanese Unexamined Patent Publication No. 2014-34673

The dispersion liquid containing fine fibrous cellulose has a wide variety of uses, and various studies have been conducted on its processing method. For example, it has been studied to form a fine fibrous cellulose-containing sheet by applying or papermaking a fine fibrous cellulose dispersion. However, it has been clarified by the studies by the present inventors that when the sheet is formed from the conventional fine fibrous cellulose dispersion, the transparency of the obtained sheet is inferior and the sheet is curled.

Therefore, in order to solve the problems of the prior art, the present inventors have proceeded with studies for the purpose of providing a sheet having excellent transparency and suppressed curl.

As a result of diligent studies to solve the above problems, the present inventors have found that the content of fibrous cellulose in a dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent. To 3.0% by mass or more with respect to the total mass of the dispersion liquid, and by setting the TI value of the dispersion liquid to 1 or more and 80,000 or less, a sheet having excellent transparency and curl suppressed can be obtained. I found.
Specifically, the present invention has the following configuration.

[1] A dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent.
The content of fibrous cellulose is 3.0% by mass or more with respect to the total mass of the dispersion liquid.
A dispersion having a TI value of 1 or more and 80,000 or less calculated under the following condition (a);
Condition (a): Using a rheometer, the viscosity (η1) of the dispersion liquid under the condition of ^{a shear rate of 1 sec -1 and the viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec -1} were measured, and TI was measured by the following formula. Calculate the value.
TI value = η1 / η2
[2] The dispersion liquid according to [1], wherein the content of fibrous cellulose is 4.0% by mass or more with respect to the total mass of the dispersion liquid.
[3] The dispersion liquid according to [1], wherein the content of fibrous cellulose is 5.0% by mass or more with respect to the total mass of the dispersion liquid.
[4] The dispersion liquid according to [1], wherein the content of fibrous cellulose is 6.0% by mass or more based on the total mass of the dispersion liquid.
[5] The ionic substituent is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group, [5]. The dispersion according to any one of 1] to [4].
[6] The dispersion liquid according to any one of [1] to [5], wherein the haze is 95% or less when the dispersion liquid has a concentration of 0.2% by mass.
[7] A sheet formed from the dispersion liquid according to any one of [1] to [6].

According to the present invention, it is possible to obtain a sheet having excellent transparency and curl suppressed.

FIG. 1 is a diagram illustrating a method of evaluating the curl resistance of a sheet. FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of a fibrous cellulose-containing slurry having a phosphorus oxo acid group. FIG. 3 is a graph showing the relationship between the amount of NaOH added dropwise to the fibrous cellulose-containing slurry having a carboxy group and the pH.

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

(Dispersion)
The dispersion liquid containing fibrous cellulose of the present embodiment is a dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent, and the content of fibrous cellulose is the total mass of the dispersion liquid. It is a dispersion liquid having a TI value of 3.0% by mass or more and 1 or more and 80,000 or less in the TI value of the dispersion liquid calculated by the following condition (a).
Condition (a): Using a rheometer, the viscosity (η1) of the dispersion liquid under the condition of ^{a shear rate of 1 sec -1 and the viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec -1} were measured, and TI was measured by the following formula. Calculate the value.
TI value = η1 / η2

In the present specification, fibrous cellulose having a fiber width of 1000 nm or less is also referred to as fine fibrous cellulose. Further, the dispersion liquid containing fine fibrous cellulose is also referred to as a fine fibrous cellulose dispersion liquid, a fine fibrous cellulose-containing dispersion liquid, or a fine fibrous cellulose-containing slurry.

Since the dispersion liquid of the present embodiment is a dispersion liquid having the above-mentioned structure, it is possible to form a sheet having excellent transparency and suppressed curl. Conventionally, in a dispersion liquid containing 3.0% by mass or more of fine fibrous cellulose, the viscosity is so high that a sheet cannot be formed from such a dispersion liquid, or even if a sheet is formed, the sheet may not be formed. The sheet had a large curl width. In addition, the formed sheet may be inferior in transparency. However, in the present embodiment, the concentration of the fine fibrous cellulose dispersion is set to a high concentration, and the TI value of such a high-concentration dispersion is controlled within a predetermined range, so that the sheet formed from the dispersion is formed. Succeeded in improving transparency and curl resistance. As described above, when the sheet is formed from the dispersion liquid of the present embodiment, a highly transparent sheet with suppressed curl can be obtained.

In the sheet formed from the dispersion liquid of the present embodiment, the generation of curl is suppressed. That is, the sheet formed from the dispersion liquid of the present embodiment has excellent curl resistance. When evaluating the curl resistance, first, a sheet for evaluation is formed. Specifically, a coating solution is prepared by mixing a solution in which each component is dispersed so that the solid content mass of the fine fibrous cellulose is 100 parts by mass and the solid content mass of the polyethylene oxide is 20 parts by mass. Next, the coating liquid is weighed so that the finished thickness of the obtained sheet (layer composed of the solid content of the coating liquid) is 40 μm to form a sheet. Next, the obtained fine fibrous cellulose-containing sheet was cut out so as to be a test piece having a width of 15 mm and a length of 130 mm, and as shown in FIG. 1, an end including one short side of the test piece 50 was formed to have a width of 30 mm ×. It is supported by a curl test jig 55 having a length of 30 mm and a height of 25 mm (a test piece having a length of 100 mm is exposed from the jig), and is placed on a horizontal table under an environment of a temperature of 23 ° C. and a relative humidity of 50%. Stand on top so that the width direction of the test piece is perpendicular to the table (the longitudinal direction of the test piece is parallel to the table). Then, the curl width at the end of the test piece 50 is measured and used as the curl width C0 (distance of C0 in FIG. 1). After standing for 24 hours, the curl width is measured again and used as C1 (distance of C1 in FIG. 1), and C1-C0 is used as the curl amount. When the value of the curl amount C1-C0 is calculated from the curl width measured in this way, C1-C0 is preferably 25 mm or less, and more preferably 5 mm or less. C1-C0 may be 0 mm. Then, when the curl is 25 mm or less, it can be determined that the sheet has excellent curl resistance.

The dispersion liquid of this embodiment is not limited to the use of the sheet. The dispersion liquid of the present embodiment is expected to be further expanded in use as a high-concentration dispersion liquid.

Further, since the dispersion liquid of the present embodiment is a dispersion liquid containing fine fibrous cellulose at a high concentration, it is possible to significantly reduce the storage cost and the transportation cost thereof. Conventionally, in the dispersion liquid containing fine fibrous cellulose, the concentration of fine fibrous cellulose has been about 2% by mass. On the other hand, in the dispersion liquid of the present embodiment, the content of the fine fibrous cellulose can be as high as 3.0% by mass or more, so that the storage cost and the transportation cost can be significantly reduced. Further, the production efficiency of the dispersion liquid can be increased.

The content of the fine fibrous cellulose may be 3.0% by mass or more based on the total mass of the dispersion liquid, preferably 4.0% by mass or more, and more preferably 5.0% by mass or more. It is preferably 6.0% by mass or more, and more preferably 6.0% by mass or more. The upper limit of the content of the fine fibrous cellulose in the dispersion is not particularly limited, but may be, for example, 20% by mass. As described above, the dispersion liquid of the present embodiment is a high-concentration fine fibrous cellulose dispersion liquid. By setting the content of the fine fibrous cellulose in the dispersion liquid within the above range, the curl resistance of the sheet can be more effectively enhanced when the sheet is formed from the dispersion liquid. This is because by forming the sheet from the high-concentration fine fibrous cellulose dispersion, the amount of water brought into the sheet manufacturing process can be reduced, and thereby the occurrence of heat shrinkage during heating can be suppressed. it is conceivable that.

The TI value of the dispersion may be 1 or more, preferably 10 or more, more preferably 30 or more, further preferably 50 or more, further preferably 70 or more, and 100 or more. Is particularly preferable. Further, the TI value of the dispersion liquid may be 80,000 or less, preferably 70,000 or less, more preferably 50,000 or less, further preferably 30,000, 20, It is particularly preferably 000 or less. By setting the TI value of the dispersion liquid within the above range, the curl resistance of the sheet can be more effectively enhanced when the sheet is formed from the dispersion liquid. Further, by setting the TI value of the dispersion liquid within the above range, when producing a sheet from the dispersion liquid, it is possible to appropriately control the spread of the dispersion liquid and impart appropriate ductility, so that the concentration is high. It is possible to produce a uniform sheet even with a dispersion liquid.

Here, the TI value of the dispersion liquid is a value calculated under the following condition (a).
Condition (a): Using a rheometer, the viscosity (η1) of the dispersion liquid under the condition of ^{a shear rate of 1 sec -1 and the viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec -1} were measured, and TI was measured by the following formula. Calculate the value.
TI value = η1 / η2
Specifically, the viscosity (η1) and the viscosity (η2) are measured under the following conditions. As the rheometer used for the measurement, for example, RheoStress6000 manufactured by HAAKE can be used.
Measurement temperature: 23 ° C
Measuring jig: Cone plate (diameter 40 mm, angle 1 °)
Shear velocity: 0.001 to 1000 sec ^-1
Number of data points: 100 points Data distribution: Log interval Measurement time: 5 minutes

The viscosity (η1) of the dispersion liquid under the condition of a shear rate of 1 sec ^-1 is preferably 1 Pa · s or more, more preferably 10 Pa · s or more, and further preferably 50 Pa · s or more. The viscosity (η1) under the condition of a shear rate of 1 sec ^-1 is preferably 5,000 Pa · s or less, more preferably 4,000 Pa · s or less, and further preferably 3,000 Pa · s or less. preferable. The viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec ^-1 is preferably 0.007 Pa · s or more, more preferably 0.01 Pa · s or more, and 0.05 Pa · s or more. Is more preferable. The viscosity (η2) under the condition of a shear rate of 1000 sec ^-1 is preferably 100 Pa · s or less, more preferably 50 Pa · s or less, and further preferably 10 Pa · s or less.

The haze when the dispersion liquid has a concentration of 0.2% by mass is preferably 95% or less, more preferably 90% or less, further preferably 80% or less, and 70% or less. More preferably, it is more preferably 50% or less, further preferably 30% or less, particularly preferably 10% or less, and most preferably 5% or less. The haze when the dispersion liquid has a concentration of 0.2% by mass may be 0%. When measuring the haze of the dispersion liquid, the haze is measured after adjusting the concentration of the fine fibrous cellulose to 0.2% by mass. The haze of the dispersion liquid is based on JIS K 7136: 2000 by putting the dispersion liquid whose concentration is adjusted to 0.2% by mass in a glass cell for liquid (manufactured by Fujiwara Seisakusho, MG-40, back light path) with an optical path length of 1 cm. , A value measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute). Before the measurement, the dispersion liquid to be measured is allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours. In addition, the zero point measurement at the time of haze measurement is performed with ion-exchanged water contained in the same glass cell. By setting the haze of the dispersion liquid having a concentration of 0.2% by mass within the above range, it becomes easy to form a sheet having excellent transparency.

When measuring the viscosity of the dispersion, measure the viscosity of the fine fibrous cellulose dispersion without diluting it. The viscosity of the dispersion liquid is the viscosity value 3 minutes after the start of measurement, with a rotation speed of 0.3 rpm at 23 ° C. using a B-type viscometer. As the B-type viscometer, for example, a digital viscometer DV2T manufactured by BLOOKFIELD can be used.

The viscosity of the dispersion liquid at a concentration of 3.0% by mass is preferably 10 million mPa · s or less, more preferably 9 million mPa · s or less, and 8 million mPa · s or less. It is more preferable to have. The viscosity of the dispersion liquid at a concentration of 3.0% by mass is preferably 100,000 mPa · s or more, more preferably 200,000 mPa · s or more, and 300,000 mPa · s or more. It is more preferable to have.
The viscosity of the dispersion liquid at a concentration of 6.0% by mass is preferably 50 million mPa · s or less, more preferably 30 million mPa · s or less, and 20 million mPa · s or less. -It is more preferably s or less. The viscosity of the dispersion liquid at a concentration of 6.0% by mass is preferably 500,000 mPa · s or more, more preferably 700,000 mPa · s or more, and 1 million mPa · s or more. It is more preferable to have.
The viscosity of the dispersion liquid at a concentration of 13.0% by mass is preferably 100 million mPa · s or less, more preferably 50 million mPa · s or less, and 30 million mPa · s. The following is more preferable. The viscosity of the dispersion liquid at a concentration of 13.0% by mass is preferably 1 million mPa · s or more, more preferably 5 million mPa · s or more, and 10 million mPa · s or more. It is more preferable to have.

The dispersion liquid of the present embodiment is preferably a dispersion liquid containing fine fibrous cellulose and a dispersion medium. The dispersion medium is not particularly limited, but preferably contains water, and more preferably a solvent containing water as a main component. That is, the dispersion liquid of the present embodiment is preferably an aqueous dispersion liquid containing fine fibrous cellulose. The dispersion medium may be an organic solvent. Examples of the organic solvent include dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), aniline, pyridine, quinoline, lutidine, acetonitrile, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dioxane, and the like. Examples thereof include ethanol and isopropanol. Further, as the dispersion medium, a mixed solvent in which these organic solvents and water are mixed can also be used.

The dispersion liquid of the present embodiment is a high-concentration dispersion liquid containing 3.0% by mass or more of fine fibrous cellulose, but is a dispersion liquid obtained without going through a concentration step. Further, the dispersion liquid of the present embodiment is also distinguished from, for example, a dispersion liquid obtained by redispersing a solid body of fine fibrous cellulose. That is, the dispersion liquid of the present embodiment is neither a concentrated dispersion liquid nor a concentrated reduction dispersion liquid. The dispersion liquid of the present embodiment is the dispersion liquid itself obtained through the defibration treatment step as described later. Therefore, the dispersion liquid of the present embodiment does not contain components involved in concentration and concentration reduction such as a flocculant.

Here, in the prior art, it has been studied to increase the concentration of fine fibrous cellulose by adding a flocculant to the dispersion liquid or by heating and concentrating the liquid. However, when the flocculant or heat concentration is performed in this way, the fine fibrous cellulose aggregates non-uniformly and, in some cases, aggregates are formed. Therefore, the TI value of the dispersion liquid exceeds 80,000 according to the present embodiment. It became clear by the examination of these. Further, even in the dispersion liquid obtained by redispersing the agglomerates and the like, the TI value of the dispersion liquid cannot be within a desired range because the fine fibrous cellulose is non-uniformly dispersed.

Further, in the prior art, it is difficult to obtain a high-concentration aqueous dispersion of 3.0% by mass or more, and obtaining a high-concentration aqueous dispersion of 6.0% by mass or 13.0% by mass itself. Was impossible. Further, even when the fine fibrous cellulose dispersion obtained in the prior art is concentrated to obtain an aqueous dispersion having a concentration of 6.0% by mass or 13.0% by mass, the aqueous dispersion is in the form of a gel. It was not possible to obtain a uniform aqueous dispersion because of the above-mentioned problems and the formation of granules (aggregates of fibers) in the aqueous dispersion. As a matter of course, it was impossible to measure the viscosity of such a high-concentration aqueous dispersion. For example, when an aqueous dispersion having a concentration of 0.5 to 2.0% by mass is subjected to a defibration treatment and then concentrated by heat treatment or an evaporator, a film-like substance is generated on the wall surface during the concentration process. Therefore, it is not possible to obtain a dispersion liquid of 6.0% by mass or more in which fine fibrous cellulose is uniformly dispersed. Therefore, it is impossible to obtain a high-concentration aqueous dispersion such as 6.0% by mass or 13.0% by mass, and in a high-concentration aqueous dispersion such as 6.0% by mass or 13.0% by mass. It is not possible to obtain a dispersion having a viscosity within the above range.

On the other hand, in the present embodiment, since the dispersion liquid obtained without going through the concentration step is used, a highly uniform dispersion liquid can be obtained. Further, the TI value of the dispersion liquid can be set in the range of 1 or more and 80,000 or less. Therefore, for example, when a sheet is formed from the dispersion liquid of the present embodiment, a sheet having high transparency and excellent curl resistance can be obtained. Further, in the present embodiment, the dispersion liquid of the phosphorylated pulp to be subjected to the defibration treatment is made to have a high concentration, and the defibration treatment is performed on such a high concentration pulp dispersion liquid, and if necessary, it will be described later. By also applying the low molecular weight treatment, the viscosity of the aqueous dispersion containing 3.0% by mass or more of fine fibrous cellulose (for example, 6.0% by mass or 13.0% by mass) can be increased. It became possible to measure and succeeded in obtaining an aqueous dispersion having a relatively low viscosity as a high-concentration dispersion.

(Fibrous cellulose)
The dispersion liquid of the present embodiment contains fibrous cellulose having a fiber width of 1000 nm or less. The fiber width of the fibrous cellulose is more preferably 100 nm or less, and further preferably 8 nm or less.

The fiber width of fibrous cellulose can be measured, for example, by observation with an electron microscope. The average fiber width of the fibrous cellulose is, for example, 1000 nm or less. The average fiber width of the fibrous cellulose is, for example, 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more and 10 nm or less. Especially preferable. By setting the average fiber width of the fibrous cellulose to 2 nm or more, it is possible to suppress the dissolution of the fibrous cellulose as a cellulose molecule in water, and to make it easier to exhibit the effects of the fibrous cellulose on improving strength, rigidity, and dimensional stability. it can. The fibrous cellulose is, for example, monofibrous cellulose.

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

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

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

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

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

The axial ratio (fiber length / fiber width) of the fibrous cellulose is not particularly limited, but is preferably, for example, 30 or more and 10000 or less, and more preferably 50 or more and 1000 or less. In the present specification, the fibrous cellulose (fine fibrous cellulose) having a fiber width of 1000 nm or less is cellulose nanofiber (CNF), and the fibrous cellulose (fine fibrous cellulose) is cellulose nanocrystal (CNC). Is not included. The axial ratio (fiber length / fiber width) of cellulose nanocrystal (CNC) is usually about 10 or more and 30 or less. Further, by setting the axial ratio of the fibrous cellulose to the above lower limit value or more, it is preferable in that handling such as dilution becomes easy when, for example, the fibrous cellulose is treated as an aqueous dispersion.

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

The fibrous cellulose in this embodiment has an ionic substituent. The ionic substituent can include, for example, either one or both of an anionic group and a cationic group. In this embodiment, it is particularly preferable to have an anionic group as the ionic substituent. Further, the ionic substituent is preferably a group that breaks the ester bond and connects to the fibrous cellulose. In this case, the ester bond is formed by dehydration condensation of the fibrous cellulose and the compound serving as an ionic substituent.

Examples of the anionic group as an ionic substituent include a phosphate group or a substituent derived from a phosphorusoxo acid group (sometimes referred to simply as a phosphorusoxo acid group), a carboxy group or a substituent derived from a carboxy group (simply a carboxy group). It is preferably at least one selected from 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), a phosphorus oxo acid group and a carboxy. It is more preferably at least one selected from the groups, and particularly preferably a phosphoroxoic acid group. By introducing a phosphorus oxo acid group into the fibrous cellulose as an ionic substituent, it becomes easy to obtain a highly transparent dispersion liquid, and as a result, it becomes easy to obtain a sheet having more excellent transparency. Further, by introducing a phosphorus oxo acid group into the fibrous cellulose, the salt resistance of the fibrous cellulose can be improved.

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

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

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

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

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

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

More specifically, the phosphate group or the substituent derived from the phosphorous acid group includes a phosphoric acid group (-PO ₃ H ₂ ), a salt of a phosphoric acid group, and a phosphite group (phosphonic acid group) (-PO). ₂ H _2), and salts of phosphorous acid (phosphonic acid group). Further, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a group in which a phosphoric acid group is condensed (for example, a pyrophosphate group), a group in which a phosphonic acid is condensed (for example, a polyphosphonic acid group), and a phosphoric acid ester group (for example). For example, it may be a monomethylphosphoric acid group, a polyoxyethylene alkylphosphoric acid group), an alkylphosphonic acid group (for example, a methylphosphonic acid group), or the like.

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

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

The amount of the ionic substituent introduced into the fibrous cellulose is, for example, 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.40 mmol / g per 1 g (mass) of the fibrous cellulose. It is more preferably / g or more, more preferably 0.60 mmol / g or more, further preferably 0.90 mmol / g or more, and particularly preferably 1.00 mmol / g or more. In particular, when the amount of the ionic substituent introduced into the fibrous cellulose is 1.00 mmol / g or more, the load at the time of defibration can be reduced, and the transparency of the obtained fine fibrous cellulose dispersion liquid or sheet is further enhanced. Further, when the amount of the ionic substituent introduced into the fibrous cellulose is 1.00 mmol / g or more, the salt resistance of the fibrous cellulose can be improved. The amount of the ionic substituent introduced into the fibrous cellulose is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of the fibrous cellulose, for example, 3 It is more preferably 0.00 mmol / g or less, further preferably 2.50 mmol / g or less, further preferably 2.00 mmol / g or less, and particularly preferably 1.50 mmol / g or less. preferable. Here, the denominator in the unit mmol / g indicates the mass of fibrous cellulose when the counter ion of the ionic substituent is a hydrogen ion (H ^+). By setting the amount of the ionic substituent introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fibrous cellulose. Further, by setting the amount of the ionic substituent introduced within the above range, it becomes easy to obtain a dispersion having a haze value within a predetermined range while containing fine fibrous cellulose at a high concentration.

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

FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of a fibrous cellulose-containing slurry having a phosphorus oxo acid group. The amount of the phosphorus oxo acid group introduced into the fibrous cellulose is measured, for example, as follows.
First, the slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the defibration treatment similar to the defibration treatment step described later may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 2 is obtained. The titration curve shown in the upper part of FIG. 2 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 2 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, two points are confirmed in which the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociating acid of the fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the first end point to the second end point. The amount is equal to the amount of the second dissociating acid of the fibrous cellulose contained in the slurry used for the titration, and the amount of alkali required from the start to the second end point of the titration is the fibrous cellulose contained in the slurry used for the titration. Is equal to the total amount of dissociated acid. Then, the value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol / g). The amount of phosphorus oxo acid group introduced (or the amount of phosphorus oxo acid group) simply means the amount of the first dissociated acid.
In FIG. 2, the region from the start of titration to the first end point is referred to as a first region, and the region from the first end point to the second end point is referred to as a second region. For example, when the phosphoric acid group is a phosphoric acid group and this phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently It decreases, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) matches the amount of phosphorus atoms regardless of the presence or absence of condensation. When the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so that the amount of alkali required for the second region is reduced or the amount of alkali required for the second region is reduced. May be zero. In this case, there is only one point on the titration curve where the pH increment is maximized.

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

FIG. 3 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of a dispersion containing fibrous cellulose having a carboxy group as an ionic substituent. The amount of the carboxy group introduced into the fibrous cellulose is measured, for example, as follows.
First, the dispersion liquid containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the defibration treatment similar to the defibration treatment step described later may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 3 is obtained. The titration curve shown in the upper part of FIG. 3 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 3 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, in the curve plotting the measured pH with respect to the amount of alkali added, one point was confirmed where the increment (differential value of pH with respect to the amount of alkali dropped) became maximum, and this maximum point was the first. Called one end point. Here, the region from the start of titration to the first end point in FIG. 3 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the dispersion used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the dispersion containing the fibrous cellulose to be titrated, so that the amount of carboxy group introduced (mmol). / G) is calculated.

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

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

The amount of sulfur oxoacid group introduced into fibrous cellulose can be calculated by measuring the amount of sulfur in a sample obtained by wet-ashing a slurry containing fibrous cellulose and then diluting it at an appropriate magnification. Specifically, fibrous cellulose is wet-ashed with perchloric acid and concentrated nitric acid, diluted at an appropriate magnification, and the amount of sulfur is measured by ICP emission analysis. The value obtained by dividing the fibrous cellulose tested by the absolute dry mass is defined as the amount of sulfur oxoacid groups (unit: mmol / g).

The degree of polymerization of the fine fibrous cellulose is preferably 800 or less, more preferably 700 or less, further preferably 450 or less, and particularly preferably 300 or less. The degree of polymerization of the fibrous cellulose is preferably 100 or more, and more preferably 150 or more. By setting the degree of polymerization of the fine fibrous cellulose within the above range, it becomes easy to obtain a dispersion having a TI value within a predetermined range while containing the fine fibrous cellulose at a high concentration.

The degree of polymerization of the fine fibrous cellulose is a value calculated from the pulp viscosity measured according to Tappi T230. Specifically, the viscosity (referred to as ηX) measured by dispersing the fine fibrous cellulose to be measured in a copper ethylenediamine aqueous solution and the blank viscosity (referred to as η0) measured only with the dispersion medium are measured and then the ratio. Viscosity (ηsp) and intrinsic viscosity ([η]) are measured according to the following formulas.
ηsp = (ηX / η0) -1
[Η] = ηsp / (c (1 + 0.28 × ηsp))
Here, c in the formula indicates the concentration of fine fibrous cellulose at the time of viscosity measurement.
Further, the degree of polymerization (DP) is calculated from the following formula.
DP = 1.75 × [η]
Since this degree of polymerization is the average degree of polymerization measured by the viscosity method, it is sometimes called "viscosity average degree of polymerization".

The fibrous cellulose according to the present embodiment and the dispersion liquid containing the fibrous cellulose have been described above. Further, in the present specification, as another embodiment, it is a fine fibrous cellulose-containing dispersion having a fiber width of 1000 nm or less and having an ionic substituent, and the content of the fine fibrous cellulose is the entire dispersion. 5.0 or less wt% or more 14.0% by weight, based on the weight, is not less 165 or more 290 or less degree of polymerization of fine fibrous cellulose, was measured using a rheometer, dispersions of shear rate 1 sec ^{- The viscosity (η1) under the condition of 1} is 60 Pa · s or more and 830 Pa · s or less, and the viscosity (η2) under the condition of ^{a shear rate of 1000 sec -1 of the dispersion liquid measured using a leometer is 0.02 Pa · s.} A fine fibrous cellulose-containing dispersion having a value of 0.56 Pa · s or less is also disclosed. As the ionic substituent, a phosphoric acid group or a substituent derived from the phosphoric acid group (among them, a phosphoric acid group) is particularly preferable. The amount of the ionic substituent introduced into the fine fibrous cellulose is particularly preferably 0.90 mmol / g or more and 2.00 mmol / g or less. The other description is the same as the description of the dispersion liquid containing fibrous cellulose according to the present embodiment, and is therefore omitted here.

(Manufacturing method of fine fibrous cellulose)
<Fiber raw material>
Fine fibrous cellulose is produced from a fiber raw material (cellulose fiber) containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, but for example, broad-leaved kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), broad-leaved dissolved pulp (LDKP, LDSP), coniferous dissolved pulp (NDKP, NDSP), Chemical pulp such as soda pulp (AP), unbleached kraft pulp (UKP) and oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), crushed wood pulp (GP) ) And mechanical pulp such as thermomechanical pulp (TMP, BCTMP). The non-wood pulp is not particularly limited, and examples thereof include cotton pulp such as cotton linter and cotton lint, and non-wood pulp such as hemp, straw and bagasse. The deinking pulp is not particularly limited, and examples thereof include deinking pulp made from recycled paper. As the pulp of the present embodiment, one of the above types may be used alone, or two or more types may be mixed and used. Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of availability. Further, among wood pulp, long fiber fine fibrous cellulose having a large cellulose ratio and a high yield of fine fibrous cellulose during defibration treatment and a large axial ratio with less decomposition of cellulose in the pulp can be obtained. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable. Among them, softwood-derived pulp is preferably used because it has good defibration properties during defibration treatment, which will be described later, and transparency when made into a dispersion liquid is further improved.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The amount of the phosphorus oxo acid group introduced into the fiber raw material is, for example, 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.40 mmol / g / g per 1 g (mass) of fine fibrous cellulose. It is more preferably g or more, more preferably 0.60 mmol / g or more, further preferably 0.90 mmol / g or more, and particularly preferably 1.00 mmol / g or more. The amount of the phosphorus oxo acid group introduced into the fiber raw material is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of fine fibrous cellulose, for example. It is more preferably 00 mmol / g or less, further preferably 2.50 mmol / g or less, further preferably 2.00 mmol / g or less, and particularly preferably 1.50 mmol / g or less. .. By setting the amount of the phosphorus oxo acid group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous cellulose. Further, by setting the amount of the phosphorus oxo acid group introduced within the above range, it becomes easy to obtain a dispersion having a haze value within a predetermined range while containing fine fibrous cellulose at a high concentration. Further, the salt resistance of the fibrous cellulose can be improved by setting the introduction amount of the phosphorus oxo acid group to 1.00 mmol / g or more.

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

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

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

When the TEMPO oxidation treatment is performed in the carboxy group introduction step, it is preferable to perform the treatment under conditions of pH 6 or more and 8 or less, for example. Such a treatment is also referred to as a neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) as a catalyst, and the like. This can be done by adding a nitroxy radical and sodium hypochlorite as a sacrificial reagent. Further, by coexisting with sodium chlorite, the aldehyde generated in the oxidation process can be efficiently oxidized to the carboxy group. Further, the TEMPO oxidation treatment may be carried out under the condition that the pH is 10 or more and 11 or less. Such a treatment is also referred to as an alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be 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 carboxy group introduced into fibrous cellulose varies depending on the type of substituent, but for example, when a carboxy group is introduced by TEMPO oxidation, it is 0.10 mmol / g or more per 1 g (mass) of fine fibrous cellulose. It is preferably 0.20 mmol / g or more, more preferably 0.40 mmol / g or more, further preferably 0.60 mmol / g or more, and 0.90 mmol / g or more. Is even more preferable, and 1.00 mmol / g or more is particularly preferable. The amount of the carboxy group introduced into the fibrous cellulose is preferably 3.65 mmol / g or less, more preferably 3.00 mmol / g or less, and further preferably 2.50 mmol / g or less. , 2.00 mmol / g or less, and even more preferably 1.50 mmol / g or less. In addition, when the substituent is a carboxymethyl group, it may be 5.8 mmol / g or less per 1 g (mass) of fine fibrous cellulose. By setting the amount of the carboxy group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fibrous cellulose. Further, by setting the amount of the carboxy group introduced within the above range, it becomes easy to obtain a dispersion having a haze value within a predetermined range while containing fine fibrous cellulose at a high concentration.

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

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

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

In the heat treatment step, it is preferable to heat until the water content is substantially eliminated. Therefore, the heat treatment time varies depending on the amount of water contained in the cellulose raw material and the amount of the aqueous solution containing sulfur oxoacid and urea and / or a urea derivative, but is, for example, 10 seconds or more and 10000 seconds or less. It is preferable to do so. Equipment having various heat media can be used for the heat treatment, for example, a hot air drying device, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, and a fluidized layer drying device. , Band type drying device, filtration drying device, vibration flow drying device, air flow drying device, vacuum drying device, infrared heating device, far infrared heating device, microwave heating device, high frequency drying device can be used.

The amount of the sulfur oxoacid group introduced into the cellulose raw material is preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g or more, still more preferably 0.20 mmol / g or more. It is more preferably 0.40 mmol / g or more, further preferably 0.60 mmol / g or more, further preferably 0.90 mmol / g or more, and 1.00 mmol / g or more. Is particularly preferable. The amount of sulfur oxoacid group introduced into the cellulose raw material is preferably 5.00 mmol / g or less, more preferably 3.00 mmol / g or less, and further preferably 2.50 mmol / g or less. It is more preferably 2.00 mmol / g or less, and particularly preferably 1.50 mmol / g or less. By setting the amount of the sulfur oxoacid group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fibrous cellulose. Further, by setting the amount of the sulfur oxoacid group introduced within the above range, it becomes easy to obtain a dispersion having a haze value within a predetermined range while containing fine fibrous cellulose at a high concentration.

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

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

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

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time of the ionic substituent-introduced fiber in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10000% by mass or less, based on the absolute dry mass of the ionic substituent-introduced fiber. The following is more preferable.

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

<Acid treatment process>
When producing fine fibrous cellulose, the fiber raw material may be subjected to acid treatment between the step of introducing an ionic substituent and the defibration treatment step described later. For example, the ionic substituent introduction step, the acid treatment, the alkali treatment, and the defibration treatment may be performed in this order.

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

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

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

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

The concentration of the cellulose fiber at the time of the defibration treatment can be appropriately set, but in the present embodiment, the concentration of the cellulose fiber at the time of the defibration treatment is preferably 3.0% by mass or more, and 4.0% by mass or more. It is more preferably 5.0% by mass or more, and 6.0% by mass or more is particularly preferable. The upper limit of the concentration of the cellulose fibers during the defibration treatment is not particularly limited, but may be, for example, 20.0% by mass. In the present embodiment, by setting the concentration of the cellulose fibers during the defibration treatment within the above range, it becomes easy to obtain a sheet having excellent transparency and curl suppressed. In addition, by setting the concentration of cellulose fibers during the defibration treatment within the above range, it is possible to obtain a highly concentrated dispersion, and it is possible to reduce costs during transportation and storage.

Further, the slurry obtained by dispersing the ionic substituent-introduced fiber in a dispersion medium may contain a solid content other than the ionic substituent-introduced fiber such as urea having a hydrogen bond property.

<Low viscosity treatment>
The method for producing fine fibrous cellulose of the present embodiment preferably includes a step of further lowering the viscosity in addition to the steps as described above. Specifically, as described above, a step of defibrating the appropriately treated cellulose fiber to obtain a fibrous cellulose having a fiber width of 1000 nm or less, and a step of applying a low viscosity treatment to the fibrous cellulose. Is preferably included. That is, it is preferable that the method for producing fine fibrous cellulose of the present embodiment includes, for example, a step of subjecting the cellulose fibers to a defibration treatment and then a viscosity reducing treatment. The viscosity reduction treatment may be performed before the defibration treatment step. For example, the viscosity reduction treatment may be performed before the defibration treatment and then the viscosity reduction treatment after the defibration treatment. Good. Further, the defibration treatment may be performed again after the viscosity reduction treatment is performed, and then the defibration treatment may be further performed. Above all, in order to reduce the viscosity more effectively, it is preferable to perform the viscosity reduction treatment after the defibration treatment.

The concentration of the fine fibrous cellulose or the cellulose fiber at the time of the low viscosity treatment can be appropriately set, but it is preferable that the concentration is the same as the concentration of the cellulose fiber at the time of the defibration treatment, for example, the fine fiber at the time of the low viscosity treatment. The concentration of the cellulose or cellulose fibers is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, further preferably 5.0% by mass or more, and 6.0% by mass. % Or more is particularly preferable. Further, the upper limit of the concentration of the fine fibrous cellulose or the cellulose fiber at the time of the low viscosity treatment is not particularly limited, but may be, for example, 20.0% by mass. In the present embodiment, by setting the concentration of the cellulose fibers at the time of the low viscosity treatment within the above range, it becomes easy to obtain a sheet having excellent transparency and curl suppressed.

Examples of the step of applying the low viscosity treatment include an ozone treatment step, an enzyme treatment step, an acid treatment step, a sub-critical water treatment step, and the like. The step of applying the low viscosity treatment is preferably at least one selected from the ozone treatment step, the enzyme treatment step and the acid treatment step, and is at least one selected from the ozone treatment step and the enzyme treatment step. Is particularly preferable.

In the ozone treatment step, ozone is added to the fine fibrous cellulose dispersion (slurry). When adding ozone, for example, it is preferable to add it as an ozone / oxygen mixed gas. At this time, the ozone addition rate with respect to 1 g of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion (slurry) ^{is preferably 1.0 × 10 -4} g or more, preferably 1.0 × 10 ^-3 g. The above is more preferable, and 1.0 × ^10-2 g or more is further preferable. The ozone addition rate with respect to 1 g of fine fibrous cellulose ^{is preferably 1.0 × 10 1} g or less. After adding ozone to the fine fibrous cellulose dispersion (slurry), the mixture may be stirred for 10 seconds or more and 10 minutes or less under the conditions of 10 ° C. or more and 50 ° C. or less, and then allowed to stand for 1 minute or more and 100 minutes or less. preferable.

In the enzyme treatment step, the enzyme is added to the fine fibrous cellulose dispersion (slurry). The enzyme used at this time is preferably a cellulase-based enzyme. Cellulase-based enzymes are classified into the sugar hydrolase family based on the higher-order structure of the catalytic domain having the function of hydrolyzing cellulose. Cellulase-based enzymes are roughly classified into endo-glucanase and cellobiohydrolase according to their cellulolytic properties. Endo-type glucanase is highly hydrolyzable to amorphous portions of cellulose, soluble cellooligosaccharides, and cellulose derivatives such as carboxymethyl cellulose, and randomly cleaves their molecular chains from the inside to reduce the degree of polymerization. In contrast, cellobiohydrolase decomposes the crystalline portion of cellulose to give cellobiose. In addition, cellobiohydrolase hydrolyzes from the end of the cellulose molecule and is also called an exo-type or processive enzyme. The enzyme used in the enzyme treatment step is not particularly limited, but it is preferable to use endo-type glucanase.

In the enzyme treatment step, it is preferable to add the enzyme so that the enzyme activity is 0.1 nkat or more, more preferably 1.0 nkat or more, and 10 nkat or more with respect to 1 g of the fine fibrous cellulose. It is more preferable to add the enzyme so that it becomes. Further, it is preferable to add the enzyme so that the enzyme activity is 100,000 nkat or less with respect to 1 g of the fine fibrous cellulose, and it is more preferable to add the enzyme so that the enzyme activity is 50,000 nkat or less. More preferred. After adding the enzyme to the fine fibrous cellulose dispersion (slurry), it is treated under the condition of 0 ° C. or higher and lower than 80 ° C. for 1 minute or more and 100 hours or less, and then placed under the condition of 80 ° C. or higher. It is preferable to inactivate the enzyme.

The acid treatment step includes, for example, sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochloric acid, chlorous acid, chloric acid, perchloric acid, phosphoric acid, boric acid, sulfonic acid (eg methane). This is a step of mixing with sulfonic acid) or the like. Above all, the acid treatment step is preferably a step of mixing with hypochlorous acid (hypochlorous acid treatment step). In the hypochlorous acid treatment step, sodium hypochlorite can also be used as the fine fibrous cellulose dispersion (slurry). ^{The addition rate of sodium hypochlorite is preferably 1.0 × 10 -4} g or more, more preferably 1.0 × 10 ^-3 g or more, with respect to 1 g of fine fibrous cellulose. It is more preferably 0 × 10 ⁻² g or more, and ^{particularly preferably 1.0 × 10 -1} g or more. ^{The addition rate of sodium hypochlorite is preferably 1.0 × 10 2} g or less with respect to 1 g of fine fibrous cellulose. After adding sodium hypochlorite to the fine fibrous cellulose dispersion (slurry), it is preferable to stir for 1 minute or more and 10 hours or less under the conditions of 10 ° C. or higher and 50 ° C. or lower.

It is preferable to further provide a defibration treatment step after the low viscosity treatment step. Above all, it is preferable to provide a defibration treatment step before and after the low viscosity treatment step. In this case, as the defibration treatment step, the same steps as those described above can be exemplified, but in particular, in the defibration treatment step after the low viscosity treatment step, a high-pressure homogenizer or an ultra-high pressure homogenizer can be used. preferable.

The present embodiment may relate to a method for producing fine fibrous cellulose, which comprises at least one step of defibrating a cellulose fiber having an ionic substituent and one step of reducing the viscosity. The method for producing fine fibrous cellulose further increases the concentration of cellulose fibers during the defibration treatment by including at least one step of defibrating the cellulose fibers having an ionic substituent and one step of reducing the molecular weight. be able to. As a result, a high-concentration fine fibrous cellulose dispersion can be efficiently obtained. In this case, the method for producing fine fibrous cellulose may include a defibration treatment step, a low viscosity treatment step, and a defibration treatment step in this order, and the low viscosity treatment step and the defibration treatment. The step, the low viscosity treatment step, and the defibration treatment step may be included in this order. In addition, it is preferable that the above-mentioned ionic substituent introduction step, washing step, alkali treatment step and the like are provided before the first defibration treatment step or low viscosity treatment step. In such a method for producing fine fibrous cellulose, the low viscosity treatment step may be at least one selected from an ozone treatment step, an enzyme treatment step, a hypochlorous acid treatment step and a subcritical water treatment step. It is particularly preferable that it is at least one selected from the ozone treatment step and the enzyme treatment step.

(Additive)
The dispersion liquid of the present embodiment may contain other additives in addition to the fine fibrous cellulose and the dispersion medium as described above. Examples of other additives include antifoaming agents, lubricants, ultraviolet absorbers, dyes, pigments, stabilizers, surfactants, preservatives (for example, phenoxyethanol) and the like. Further, the fibrous cellulose dispersion liquid may contain a hydrophilic polymer, a hydrophilic low molecule, an organic ion or the like as optional components.

The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (excluding the above-mentioned cellulose fibers), and examples of the oxygen-containing organic compound include polyethylene glycol, polyethylene oxide, casein, dextrin, starch, and modification. Distillate, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), polyethylene oxide, polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylates, acrylic acid alkyl ester copolymer, urethane copolymer, cellulose derivative (hydroxy) Hydrophilic polymers such as ethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.) can be mentioned.

The hydrophilic low molecule is preferably a hydrophilic oxygen-containing organic compound, and more preferably a polyhydric alcohol. Examples of the polyhydric alcohol include glycerin, sorbitol, ethylene glycol and the like.

Examples of the organic ion include tetraalkylammonium ion and tetraalkylphosphonium ion. Examples of the tetraalkylammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, and lauryltrimethyl. Examples thereof include ammonium ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion and tributylbenzylammonium ion. Examples of the tetraalkylphosphonium ion include tetramethylphosphonium ion, tetraethylphosphonium ion, tetrapropylphosphonium ion, tetrabutylphosphonium ion, and lauryltrimethylphosphonium ion. Further, examples of the tetrapropyl onium ion and the tetrabutyl onium ion include tetra n-propyl onium ion and tetra n-butyl onium ion, respectively.

(Manufacturing method of dispersion liquid)
The present embodiment may relate to the above-mentioned method for producing a fine fibrous cellulose dispersion liquid. The method for producing the fine fibrous cellulose dispersion liquid includes a step of defibrating the cellulose fiber having an ionic substituent (defibration treatment step) and a step of reducing the viscosity (low viscosity treatment step). Here, the concentration of the cellulose fibers in the defibration treatment step is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, and further preferably 5.0% by mass or more. It is preferably 6.0% by mass or more, and particularly preferably 6.0% by mass or more. Further, the concentration of the fine fibrous cellulose or the cellulose fiber in the low viscosity treatment step is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, and 5). It is more preferably 0.0% by mass or more, and particularly preferably 6.0% by mass or more.

The step of reducing the viscosity may be provided before the defibration treatment step, or may be provided after the defibration treatment step. Further, the step of reducing the viscosity may be provided before and after the defibration treatment step. For example, the viscosity reduction treatment may be performed before the defibration treatment, and then the viscosity reduction treatment may be further performed after the defibration treatment. Further, after the viscosity reducing treatment is performed, the defibration treatment may be performed, and after the viscosity reduction treatment is further performed, the defibration treatment step may be performed again. Above all, the step of reducing the viscosity is preferably provided after the defibration treatment step. Examples of the low viscosity treatment include the above-mentioned treatments.

In the method for producing the dispersion liquid of the present embodiment, both the defibration treatment step and the low viscosity treatment step are included, and the content of the fibrous cellulose is increased by increasing the concentration of the cellulose fibers in the defibration treatment step. We succeeded in obtaining a high-concentration dispersion of 3.0% by mass or more based on the total mass of the dispersion. Further, in the method for producing a dispersion liquid of the present embodiment, the TI value of the dispersion liquid can be set to 1 or more and 80,000 or less by providing a low viscosity treatment step in addition to such a defibration treatment step.

In the method for producing the dispersion liquid of the present embodiment, the fine fibrous cellulose dispersion obtained after the defibration treatment step is performed by setting the concentration of the cellulose fibers in the defibration treatment step to 3.0% by mass or more. The concentration of the liquid can be 3.0% by mass or more. Therefore, in the method for producing the dispersion liquid of the present embodiment, it is not necessary to provide a concentration step. The method for producing the dispersion liquid of the present embodiment preferably does not include a concentration step. Examples of the concentration step include a step of concentrating using a coagulant, a step of heating and concentrating, and the like.

(Use)
The dispersion liquid of the present embodiment is a dispersion liquid containing fine fibrous cellulose at a high concentration. Therefore, it is particularly preferably used in applications where it is desired to add fine fibrous cellulose at a high concentration. For example, the fine fibrous cellulose of the present embodiment is used as an additive to foods, cosmetics, cement, paints (for painting vehicles such as automobiles, ships, aircraft, etc., for building materials, for daily necessities, etc.), inks, pharmaceuticals, and the like. Can be done. Further, the fine fibrous cellulose of the present embodiment can be added to a resin-based material or a rubber-based material.

Further, when a sheet or a coating film is formed from the dispersion liquid of the present embodiment containing a high concentration of fine fibrous cellulose, the mechanical strength of the obtained sheet or coating film can be increased. For example, the tensile strength and tensile elastic modulus of the sheet or coating film can be increased more effectively. Further, since the dispersion liquid of the present embodiment is highly transparent, the transparency of the obtained sheet or coating film can be enhanced. As described above, the fine fibrous cellulose dispersion liquid of the present embodiment is preferably a dispersion liquid for forming a sheet, and the present embodiment may relate to the above-mentioned sheet containing the fine fibrous cellulose.

Further, when a sheet or a coating film is formed from the dispersion liquid of the present embodiment containing a high concentration of fine fibrous cellulose, a sheet or a coating film having a high basis weight can be obtained.

When producing a sheet from the dispersion liquid of the present embodiment, it is preferable to include a coating step of coating the dispersion liquid on a base material or a papermaking step of papermaking the dispersion liquid.

In the coating process, for example, a slurry (coating liquid) containing fibrous cellulose is applied onto a base material, and the sheet formed by drying the slurry (coating liquid) is peeled off from the base material to obtain a sheet. By using a coating device and a long base material, sheets can be continuously produced. The papermaking process is performed by making a slurry with a paper machine. The paper machine used in the paper making process is not particularly limited, and examples thereof include continuous paper machines such as a long net type, a circular net type, and an inclined type, and a multi-layer paper making machine combining these. In the papermaking process, a known papermaking method such as hand-making may be adopted.

A resin layer or an inorganic layer may be further laminated on the sheet formed from the dispersion liquid of the present embodiment.

In addition, the present embodiment may have the following configurations.
<101> A fine fibrous cellulose-containing dispersion having a fiber width of 1000 nm or less and having an ionic substituent.
The content of fine fibrous cellulose is 5.0% by mass or more and 14.0% by mass or less with respect to the total mass of the dispersion liquid.
The degree of polymerization of the fine fibrous cellulose is 165 or more and 290 or less.
The viscosity (η1) of the dispersion liquid measured using a rheometer under ^{the condition of a shear rate of 1 sec -1} is 60 Pa · s or more and 830 Pa · s or less.
The viscosity (η2) of the dispersion liquid measured using a rheometer under ^{the condition of a shear rate of 1000 sec -1} is 0.02 Pa · s or more and 0.56 Pa · s or less.
Fine fibrous cellulose-containing dispersion.
<102> The fine fibrous cellulose-containing dispersion according to <101>, wherein the ionic substituent is a phospholic acid group or a substituent derived from a phosphoxoic acid group.
<103> The fine fibrous cellulose-containing dispersion according to <101> or <102>, wherein the amount of the ionic substituent introduced into the fine fibrous cellulose is 0.90 mmol / g or more and 2.00 mmol / g or less.

<111> A step of subjecting a cellulose fiber having an ionic substituent to a defibration treatment to obtain a fibrous cellulose having a fiber width of 1000 nm or less.
A method for producing a fibrous cellulose-containing dispersion, which comprises a step of subjecting the fibrous cellulose to a low-viscosity treatment.
The content of fibrous cellulose is 3.0% by mass or more with respect to the total mass of the dispersion liquid.
A method for producing a fibrous cellulose-containing dispersion, wherein the TI value of the dispersion calculated according to the following condition (a) is 1 or more and 80,000 or less;
Condition (a): Using a rheometer, the viscosity (η1) of the dispersion liquid under the condition of ^{a shear rate of 1 sec -1 and the viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec -1} were measured, and TI was measured by the following formula. Calculate the value.
TI value = η1 / η2
<112> The fibrous cellulose-containing dispersion according to <111>, wherein the concentration of cellulose fibers in the step of obtaining fibrous cellulose having a fiber width of 1000 nm or less by performing a defibration treatment is 3.0% by mass or more. Production method.
<113> The fiber according to <111> or <112>, wherein the step of applying the low viscosity treatment is at least one selected from an ozone treatment step, an enzyme treatment step, an acid treatment step, and a sub-critical water treatment step. A method for producing a state-like cellulose-containing dispersion.
<114> The method for producing a fibrous cellulose-containing dispersion according to any one of <111> to <113>, which comprises a step of further performing a defibration treatment after a step of performing a low viscosity treatment.
<115> A dispersion liquid produced by the method for producing a fibrous cellulose-containing dispersion liquid according to any one of <111> to <114>.

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

<Manufacturing example 1>
[Manufacture of phosphorylated fine fibrous cellulose dispersion]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml). The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphoric acid group into the cellulose in the pulp to obtain a phosphorylated pulp.

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

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

The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, ^{absorption based on the phosphate group was observed around 1230 cm -1} , and it was confirmed that the phosphate group was added to the pulp.

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

Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 3% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 2>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 3>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 13% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 4>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 5>
[Production of TEMPO Oxidized Fine Fibrous Cellulose Dispersion]
As the raw material pulp, softwood kraft pulp (undried) made by Oji Paper was used. Alkaline TEMPO oxidation treatment was carried out on this raw material pulp as follows. First, the raw material pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10000 parts by mass of water. Dispersed in. Then, a 13% by mass sodium hypochlorite solution was added so that the amount of sodium hypochlorite was 3.8 mmol with respect to 1.0 g of pulp, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change was observed in the pH.

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

The dehydrated sheet was subjected to additional oxidation treatment of the remaining aldehyde groups as follows. The dehydrated sheet corresponding to 100 parts by mass of dry mass was dispersed in 10000 parts by mass of 0.1 mol / L acetate buffer (pH 4.8). Next, 113 parts by mass of 80% by mass of sodium chlorite was added, and the mixture was immediately sealed and then reacted at room temperature for 48 hours with stirring at 500 rpm using a magnetic stirrer to obtain a pulp slurry.

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

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

Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 3% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 6>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 5 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 7>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 5 to prepare a slurry having a solid content concentration of 13% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 8>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 5 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 9>
[Manufacture of subphosphorylated fine fibrous cellulose dispersion]
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 ml). The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of phosphorous acid (phosphonic acid) and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to add 33 parts by mass of phosphorous acid (phosphonic acid), 120 parts by mass of urea, and 150 parts of water. The amount was adjusted to be parts by mass, and a chemical-impregnated pulp was obtained. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 250 seconds to introduce a phosphorous acid group into the cellulose in the pulp to obtain a phosphorylated pulp.

Next, the obtained subphosphorylated pulp was washed. In the washing treatment, the pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of subphosphorized pulp is stirred so that the pulp is uniformly dispersed, and then the operation of filtering and dehydrating is repeated. Was done by. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

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

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

Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 3% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 10>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 9 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 11>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 9 to prepare a slurry having a solid content concentration of 13% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 12>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 9 to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 13>
Phosphorylated pulp was obtained by performing the same treatment except that the pulp of Production Example 1 was made into a hardwood pulp (dry sheet) manufactured by Oji Paper Co., Ltd. Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 14>
A fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 13 except that the slurry was prepared so that the solid content concentration of the phosphorylated pulp obtained in Production Example 13 was 13% by mass. It was.

<Manufacturing example 15>
The same treatment was carried out except that the pulp of Production Example 5 was a hardwood pulp (undried) manufactured by Oji Paper Co., Ltd. to obtain TEMPO oxidized pulp. Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 13% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 16>
Sub-phosphorylated pulp was obtained by performing the same treatment except that the pulp of Production Example 9 was made into a hardwood pulp (dry sheet) manufactured by Oji Paper Co., Ltd. Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 17>
A fibrous cellulose dispersion containing fine fibrous cellulose was prepared in the same manner as in Production Example 16 except that the slurry was prepared so that the solid content concentration of the subphosphorylated pulp obtained in Production Example 16 was 13% by mass. Obtained.

<Manufacturing example 18>
[Pre-hydrolysis]
300 g of softwood chips were collected by absolute dry mass and immersed in 10 liters of tap water overnight. Then, the chips were taken out, emptied into a 400 mesh sieve, and filtered. The dehydrated chips are placed in a 2.5 liter capacity autoclave, tap water is added so that the liquid mass ratio (assuming the mass of the chips after absolute drying is 1) is 3, and then 30 at 165 ° C. It was heated for minutes and pre-hydrolyzed. The P factor at this time was 380.
[Cooking]
After pre-hydrolysis, waste gas was extracted from the degassing cock of the autoclave, and after confirming that the pressure in the autoclave became 0, the treated chips were passed through a 400 mesh sieve and filtered. The chips after filtration were placed in an autoclave having a capacity of 2.5 liters again, a cooking solution was added so that the liquid ratio was 5, and craft cooking was carried out under the conditions of a cooking temperature of 165 ° C. and a cooking time of 120 minutes. The cooking liquid contained 21% by mass of active alkali with respect to the absolute dry mass of the chips, and the sulfurization degree was 28%. After cooking, the black liquor and pulp were separated, and the pulp was carefully selected on a flat screen equipped with an 8-cut screen plate to obtain pulp after cooking.
[bleaching]
After cooking, 70 g of pulp was collected by absolute dry mass, and 2.0 mass% of caustic soda was added to the total mass of the absolute dry pulp, and then diluted with ion-exchanged water to adjust the pulp concentration to 10 mass%. This slurry was placed in an indirect heating type autoclave, 99.9% compressed oxygen gas was injected to adjust the gauge pressure to 0.5 MPa, and oxygen exposure was performed at 100 ° C. for 60 minutes. After the oxygen exposure was completed, the pressure was reduced until the gauge pressure became 0.05 MPa or less, the pulp was taken out from the autoclave, washed with 7 liters of ion-exchanged water, and then dehydrated. In this way, pulp was obtained after oxygen exposure.
After oxygen exposure, 60 g of pulp was collected by absolute dry mass, placed in a plastic bag, and ion-exchanged water was added to adjust the pulp concentration to 10% by mass. Then, 1.8% by mass of chlorine dioxide was added to the total mass of the absolute dry pulp, and the pulp was immersed in a constant temperature water bath at a temperature of 70 ° C. for 70 minutes (D0 stage treatment). The pulp obtained after the D0 step treatment was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with Buchner funnel. Put the pulp after the D0 stage treatment in a plastic bag, add ion-exchanged water to adjust the pulp concentration to 10% by mass, and then add 1.0% by mass of caustic soda and hydrogen peroxide to the total mass of the absolute dry pulp. It was added so as to be 0.3% by mass and mixed well. Then, the E / P stage treatment was performed by immersing in a constant temperature water tank having a temperature of 70 ° C. for 100 minutes. The obtained pulp was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with Buchner funnel. The pulp after the E / P stage treatment is placed in a plastic bag, the pulp concentration is adjusted to 10% by mass using ion-exchanged water, and then 0.3% by mass of chlorine dioxide is added to the total mass of the absolute dry pulp. It was immersed in a constant temperature water tank having a temperature of 70 ° C. for 80 minutes to perform a D1 stage bleaching treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with Büchner funnel to obtain bleached pulp.
[Phosphorylation]
Using this bleached pulp, the same treatment as in Production Example 1 was carried out to obtain phosphorylated pulp.
[Defibration]
Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 19>
A fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 18 except that the slurry was prepared so that the solid content concentration of the phosphorylated pulp obtained in Production Example 18 was 13% by mass. It was.

<Manufacturing example 20>
The same treatment as in Production Example 5 was carried out except that the bleached pulp of Production Example 18 was used to obtain TEMPO oxidized pulp. Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 21>
A fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 20 except that the slurry was prepared so that the solid content concentration of the TEMPO oxidized pulp obtained in Production Example 20 was 13% by mass. It was.

<Manufacturing example 22>
The same treatment as in Production Example 9 was carried out except that the bleached pulp of Production Example 18 was used to obtain subphosphorylated pulp. Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 13% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 23>
Phosphorylated pulp was obtained by performing the same treatment as in Production Example 1 except that the pulp of Production Example 1 was a hardwood kraft pulp (dry sheet) manufactured by Celulose Nipo. Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 24>
A fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 23, except that the slurry was prepared so that the solid content concentration of the phosphorylated pulp obtained in Production Example 23 was 13% by mass. It was.

<Manufacturing example 25>
The raw material pulp of Production Example 5 was a hardwood kraft pulp (dry sheet) manufactured by Senibra Co., Ltd., and ion-exchanged water was added thereto to prepare a slurry having a pulp concentration of 2% by mass. The disperser was stirred well at 4000 rpm to prepare a pulp slurry, which was then dehydrated well in a mesh bag to obtain wet pulp. The obtained wet pulp was subjected to the same treatment as in Production Example 5 to obtain TEMPO oxidized pulp. Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

<Manufacturing example 26>
A fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 25, except that the slurry was prepared so that the solid content concentration of the TEMPO oxidized pulp obtained in Production Example 25 was 13% by mass. It was.

<Manufacturing example 27>
Subphosphorylated pulp was obtained by performing the same treatment as in Production Example 9 except that the raw material pulp of Production Example 9 was a hardwood kraft pulp (dry sheet) manufactured by Celulose Nipo. Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

<Manufacturing example 28>
A fibrous cellulose dispersion containing fine fibrous cellulose was prepared in the same manner as in Production Example 27, except that the slurry was prepared so that the solid content concentration of the subphosphorylated pulp obtained in Production Example 27 was 13% by mass. Obtained.

<Manufacturing example 29>
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 g / m ² sheets, separated and measured according to JIS P 8121, Canadian standard drainage degree (CSF) is 700 ml) It was used. The raw material pulp was sulfated as follows. First, a mixed aqueous solution of amidosulfate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to adjust the amount to 38 parts by mass of amidosulfate, 120 parts by mass of urea, and 150 parts by mass of water. Impregnated pulp was obtained. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 20 minutes to introduce a sulfate group into the cellulose in the pulp to obtain a sulfated pulp.

Next, the obtained sulfated pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of sulfated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. went. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set. Next, the sulfated pulp after washing was neutralized as follows. First, the washed sulfated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a sulfated pulp slurry having a pH of 12 or more and 13 or less. .. Then, the sulfated pulp slurry was dehydrated to obtain a neutralized sulfated pulp. Next, the sulfated pulp after the neutralization treatment was subjected to the above washing treatment.

The infrared absorption spectrum of the sulfated pulp thus obtained was measured using FT-IR. As a result, it was confirmed that a sulfate group (absorption based on a sulfone group was observed and a sulfate group (sulfone group) was added to the pulp in the vicinity of ^{1220-1260 cm -1. Also, it was obtained by X-ray diffraction.} It was confirmed that the sulfated pulp maintained the cellulose type I crystal.

Ion-exchanged water was added to the obtained sulfated pulp to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of sulfate group measured by the measuring method described in [Measurement of sulfur oxoacid group amount] described later was 1.47 mmol / g.

<Example 1>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 1 (solid content concentration: 3% by mass, solid content: 30 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion.

The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 2>
An enzyme-containing liquid having an activity of 16500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 1 (solid content concentration: 3% by mass, solid content: 30 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 3>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 1 (solid content concentration 3.5% by mass, solid content 35 g), 145 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added. , Mix well at room temperature. At this time, the addition rate of sodium hypochlorite was 0.5 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 4>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 5 (solid content concentration 3% by mass, solid content 30 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 5>
An enzyme-containing liquid having an activity of 16500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 5 (solid content concentration: 3% by mass, solid content: 30 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. A fine fibrous cellulose dispersion was obtained. Then, the temperature was set to 100 ° C., and the enzyme was heat-inactivated. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 6>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 5 (solid content concentration 3.5% by mass, solid content 35 g), 145 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added. , Mix well at room temperature. At this time, the addition rate of sodium hypochlorite was 0.5 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 7>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 9 (solid content concentration: 3% by mass, solid content: 30 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 8>
An enzyme-containing liquid having an activity of 16500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 9 (solid content concentration: 3% by mass, solid content: 30 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 9>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 9 (solid content concentration 3.5% by mass, solid content 35 g), 145 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added. , Mix well at room temperature. At this time, the addition rate of sodium hypochlorite was 0.5 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 3% by mass.

<Example 10>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 2 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 11>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 2 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and enzyme-treated at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 12>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 6 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 13>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 6 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 14>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 10 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 15>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 10 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 16>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 3 (solid content concentration 13% by mass, solid content 130 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fine fibrous cellulose dispersion liquid. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 17>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 3 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 71500 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa, and then heat-inactivated at 100 ° C. to form fine fibers. A cellulose dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 18>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 7 (solid content concentration 13% by mass, solid content 130 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fine fibrous cellulose dispersion liquid. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 19>
An enzyme-containing liquid having an activity of 71500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 7 (solid content concentration: 13% by mass, solid content: 130 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa, and then heat-inactivated at 100 ° C. to form fine fibers. A cellulose dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 20>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 11 (solid content concentration 13% by mass, solid content 130 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fine fibrous cellulose dispersion liquid. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 21>
An enzyme-containing liquid having an activity of 71500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 11 (solid content concentration: 13% by mass, solid content: 130 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was further treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa, and then heat-inactivated at 100 ° C. to form fine fibers. A cellulose dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 22>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 6% by mass. In 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g), ozone was added so as to have a ratio of 0.2 parts by mass with respect to 1 part by mass of fine fibrous cellulose, and the temperature was 25 ° C. After stirring, it was allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fibrous cellulose dispersion liquid. The obtained fibrous cellulose dispersion was treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 23>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 6% by mass. An enzyme-containing liquid having an activity of 33000 nkat was added to 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa, and then the enzyme treatment was proceeded. Then, it was treated three times at a pressure of 200 MPa to heat inactivate it at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 24>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 5 to prepare a slurry having a solid content concentration of 6% by mass. In 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g), ozone was added so as to have a ratio of 0.2 parts by mass with respect to 1 part by mass of fine fibrous cellulose, and the temperature was 25 ° C. After stirring, it was allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fibrous cellulose dispersion liquid. The obtained fibrous cellulose dispersion was treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 25>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 5 to prepare a slurry having a solid content concentration of 6% by mass. An enzyme-containing liquid having an activity of 33000 nkat was added to 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa, and then the enzyme treatment was proceeded. Then, it was treated three times at a pressure of 200 MPa to heat inactivate it at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 26>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 9 to prepare a slurry having a solid content concentration of 6% by mass. In 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g), ozone was added so as to have a ratio of 0.2 parts by mass with respect to 1 part by mass of fine fibrous cellulose, and the temperature was 25 ° C. After stirring, it was allowed to stand for 30 minutes. Next, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion liquid to obtain a fibrous cellulose dispersion liquid. The obtained fibrous cellulose dispersion was treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) four times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 27>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 9 to prepare a slurry having a solid content concentration of 6% by mass. An enzyme-containing liquid having an activity of 33000 nkat was added to 1000 g of this slurry (solid content concentration 6% by mass, solid content 60 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained slurry was treated once with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) at a pressure of 200 MPa, and then the enzyme treatment was proceeded. Then, it was treated three times at a pressure of 200 MPa to heat inactivate it at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 28>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 4 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 29>
An enzyme-containing liquid having an activity of 33000 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 4 (solid content concentration 6% by mass, solid content 60 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 30>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 4 to prepare a slurry having a solid content concentration of 7.5% by mass. This slurry is treated once with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose, and then 1000 g (solid) of this dispersion. 250 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added to a component concentration of 7.5% by mass and a solid content of 75 g), and the mixture was mixed well at room temperature. At this time, the addition rate of sodium hypochlorite was 0.4 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 31>
Ozone was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 8 (solid content concentration 6% by mass, solid content 60 g) at a ratio of 0.2 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The mixture was added, stirred at 25 ° C. in a closed container, and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 32>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 8 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 33>
Ion-exchanged water was added to the TEMPO oxidized pulp obtained in Production Example 8 to prepare a slurry having a solid content concentration of 7.5% by mass. This slurry is treated once with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose, and then 1000 g (solid) of this dispersion. 250 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added to a component concentration of 7.5% by mass and a solid content of 75 g), and the mixture was stirred at room temperature. At this time, the addition rate of sodium hypochlorite was 0.4 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 34>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 12 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 35>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 12 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 36>
Ion-exchanged water was added to the subphosphorylated pulp obtained in Production Example 12 to prepare a slurry having a solid content concentration of 7.5% by mass. This slurry is treated once with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose, and then a fine fibrous cellulose dispersion. 250 g of a sodium hypochlorite solution (effective chlorine concentration 12% by mass) was added to 1000 g (solid content concentration 7.5% by mass, solid content 75 g), and the mixture was stirred at room temperature. At this time, the addition rate of sodium hypochlorite was 0.4 parts by mass with respect to 1 part by mass of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 37>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 13 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 38>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 18 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 39>
An enzyme-containing liquid having an activity of 71500 nkat was added to 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 14 (solid content concentration: 13% by mass, solid content: 130 g) and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 40>
The ratio of the fine fibrous cellulose dispersion obtained in Production Example 19 to 1000 g (solid content concentration: 13% by mass, solid content: 130 g) is 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Ozone was added to the mixture, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 41>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 20 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 42>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 15 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 71500 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 43>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 16 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 44>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 22 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 71500 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 45>
In 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 23 (solid content concentration 6% by mass, solid content 60 g), ozone is contained in a proportion of 0.2 parts by mass with respect to 1 part by mass of fine fibrous cellulose. Was added, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 46>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 24 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 104,000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 800 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 47>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 25 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 48,000 nkat was added and enzyme-treated at a temperature of 50 ° C. The amount of enzyme added at this time was set to 800 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizer (manufactured by Sugino Machine Co., Ltd., Starburst) to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 48>
The ratio of the fine fibrous cellulose dispersion obtained in Production Example 26 to 1000 g (solid content concentration: 13% by mass, solid content: 130 g) is 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Ozone was added to the mixture, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 49>
The ratio of the fine fibrous cellulose dispersion obtained in Production Example 27 to 1000 g (solid content concentration 6% by mass, solid content 60 g) is 0.2 parts by mass with respect to 1 part by mass of the fine fibrous cellulose. Ozone was added to the mixture, and the mixture was stirred at 25 ° C. in a closed container and then allowed to stand for 30 minutes. Then, the container was opened and stirred for 5 hours to volatilize the ozone remaining in the dispersion. The obtained fine fibrous cellulose dispersion was treated three times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 50>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 28 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 104,000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 800 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst), and then heat-inactivated at 100 ° C. to obtain fine fibrous cellulose. A dispersion was obtained. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 51>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 4 (solid content concentration 6% by mass, solid content 60 g), an enzyme-containing liquid having an activity of 33000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. Then, it was heat-inactivated at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

<Example 52>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 3 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 71500 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 550 nkat per 1 g of fine fibrous cellulose. Then, it was heat-inactivated at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 53>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 7 was used.

<Example 54>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 11 was used.

<Example 55>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 14 was used.

<Example 56>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 15 was used.

<Example 57>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 17 was used.

<Example 58>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 19 was used.

<Example 59>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 21 was used.

<Example 60>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 52, except that the fine fibrous cellulose dispersion obtained in Production Example 22 was used.

<Example 61>
To 1000 g of the fine fibrous cellulose dispersion obtained in Production Example 24 (solid content concentration 13% by mass, solid content 130 g), an enzyme-containing liquid having an activity of 104,000 nkat was added and subjected to enzyme treatment at a temperature of 50 ° C. The amount of enzyme added at this time was set to 800 nkat per 1 g of fine fibrous cellulose. The obtained fine fibrous cellulose dispersion was heat-inactivated at 100 ° C. to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 13% by mass.

<Example 62>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 61, except that the fine fibrous cellulose dispersion obtained in Production Example 26 was used.

<Example 63>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 61 except that the fine fibrous cellulose dispersion obtained in Production Example 28 was used.

<Example 64>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 29, except that the fine fibrous cellulose dispersion obtained in Production Example 29 was used.

It was confirmed by X-ray diffraction that the fine fibrous celluloses of Examples 1 to 64 maintained the cellulose type I crystals. Moreover, when the fiber width of these fine fibrous celluloses was measured using a transmission electron microscope, all of them contained fine fibrous celluloses having a diameter of 3 to 5 nm.

<Comparative example 1>
Ion-exchanged water was added to softwood bleached kraft pulp (NBKP) to prepare a slurry having a solid content concentration of 6% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion. The concentration of the fine fibrous cellulose in the fine fibrous cellulose dispersion was 6% by mass.

It was confirmed by X-ray diffraction that this fine fibrous cellulose maintained the cellulose type I crystal. The number average fiber width of the fine fibrous cellulose contained in this dispersion was 1000 nm or less.

<Comparative example 2>
Ion-exchanged water was added to the phosphorylated pulp obtained in Production Example 1 to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 5 times at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous cellulose. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Comparative example 3>
The fine fibrous cellulose dispersion obtained by the same method as in Comparative Example 2 is concentrated at 50 ° C. until the concentration of the fine fibrous cellulose reaches 6% by mass, and is fibrous containing the fine fibrous cellulose. A cellulose dispersion was obtained. The amount of phosphate group (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Comparative example 4>
The dispersion of the fine fibrous cellulose obtained by the same method as in Comparative Example 2 was diluted to 0.4% by mass. 1 g of calcium chloride was added as a concentrating agent to 100 mL of the diluted solution to gelate the mixture, and the mixture was filtered and pressed with a filter paper. After immersing in 100 mL of a 0.1 N hydrochloric acid aqueous solution for 30 minutes, the mixture was filtered to obtain a concentrate having a solid content concentration of 20% by mass. After diluting with ion-exchanged water so that the concentration of the obtained concentrate was 6%, the mixture was stirred, but a uniform dispersion was not obtained.

<Measurement>
[Measurement of phosphorus oxo acid group amount]
The amount of phosphorus oxo acid groups in the fine fibrous cellulose is a fibrous form prepared by diluting a fine fibrous cellulose dispersion containing the target fine fibrous cellulose with ion exchange water so that the content is 0.2% by mass. The measurement was performed by treating the cellulose-containing slurry with an ion exchange resin and then performing titration with an alkali.
In the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, which has been conditioned) with a volume of 1/10 is added to the fibrous cellulose-containing slurry, and the mixture is shaken for 1 hour. , The resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm.
For titration using alkali, the change in pH value indicated by the slurry is measured while adding 10 μL of a 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry treated with an ion exchange resin every 5 seconds. I went by doing. The titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 2). The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated was defined as the amount of phosphorus oxo acid groups (mmol / g).

[Measurement of carboxy group amount]
The amount of carboxy group of the fine fibrous cellulose is a fibrous cellulose prepared by diluting a fine fibrous cellulose dispersion containing the target fine fibrous cellulose with ion exchange water so that the content is 0.2% by mass. The contained slurry was treated with an ion exchange resin and then titrated with an alkali to measure the content.
In the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, which has been conditioned) with a volume of 1/10 is added to the fibrous cellulose-containing slurry, and the mixture is shaken for 1 hour. , The resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm.
In the titration using alkali, 50 μL of a 0.1 N sodium hydroxide aqueous solution is added to the fibrous cellulose-containing slurry treated with an ion exchange resin once every 30 seconds to obtain the electrical conductivity of the slurry. This was done by measuring the change in value. For the carboxy group amount (mmol / g), the alkali amount (mmol) required in the region corresponding to the first region shown in FIG. 3 of the measurement results is divided by the solid content (g) in the slurry to be titrated. Calculated.

[Measurement of sulfur oxoacid group amount]
The obtained fibrous cellulose was wet-ashed with perchloric acid and concentrated nitric acid, diluted at an appropriate magnification, and the amount of sulfur was measured by ICP emission spectrometry. The value obtained by dividing this amount of sulfur by the absolute dry mass of the fibrous cellulose used was defined as the amount of sulfur oxoacid groups (unit: mmol / g).

[Measurement of viscosity of fine fibrous cellulose dispersion by rheometer]
The viscosities of the fine fibrous cellulose dispersions obtained in Examples 1 to 64 and Comparative Examples 1 to 3 were measured using a rheometer (RheoStress6000, manufactured by HAAKE). The shear rate was changed under the following conditions.
Measurement temperature: 23 ° C
Measuring jig: Cone plate (diameter 40 mm, angle 1 °)
Shear velocity: 0.001 to 1000 sec ^-1
Number of data points: 100 points Data distribution: Log interval Measurement time: 5 minutes

<Calculation of TI value>
The viscosity of the fine fibrous cellulose dispersion was measured by the method described above, and the viscosity value (η1) measured under the condition of ^{a shear rate of 1 sec -1} was the viscosity value (η2) measured under the condition of ^{a shear rate of 1000 sec -1.} The value obtained by dividing by is taken as the thixotropic index value (TI value) of the thickener.
That is, the TI value was calculated by the following formula.
TI value = η1 / η2
.eta.1: Viscosity was measured at a shear rate of 1 sec ^-1 .eta.2: viscosity measured under the conditions of a shear rate of 1,000 sec ^-1

[Measurement of specific viscosity and degree of polymerization of fine fibrous cellulose]
The specific viscosity and degree of polymerization of the fine fibrous cellulose were measured according to Tappi T230. That is, after measuring the viscosity (referred to as ηX) measured by dispersing the fine fibrous cellulose to be measured in a dispersion medium and the blank viscosity (referred to as η0) measured only with the dispersion medium, the specific viscosity (ηsp), The intrinsic viscosity ([η]) was measured according to the following formula.
ηsp = (ηX / η0) -1
[Η] = ηsp / (c (1 + 0.28 × ηsp))
Here, c in the formula indicates the concentration of cellulose fibers at the time of viscosity measurement.
Further, the degree of polymerization (DP) of the fine fibrous cellulose was calculated from the following formula.
DP = 1.75 × [η]
Since this degree of polymerization is the average degree of polymerization measured by the viscosity method, it is sometimes called "viscosity average degree of polymerization".

[Measurement of haze of fine fibrous cellulose dispersion]
The haze of the fine fibrous cellulose dispersions obtained in Examples 1 to 64 and Comparative Examples 1 to 3 was measured after diluting the fine fibrous cellulose dispersion with ion-exchanged water to 0.2% by mass. Measured in accordance with JIS K 7136: 2000 with a meter (HM-150 manufactured by Murakami Color Technology Research Institute) using a liquid glass cell (manufactured by Fujiwara Seisakusho, MG-40, backlight path) with an optical path length of 1 cm. did. The zero point measurement was performed with ion-exchanged water contained in the same glass cell. The dispersion to be measured was allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours before the measurement. The liquid temperature of the dispersion liquid at the time of measurement was 23 ° C.

<Evaluation>
[Visual evaluation of fine fibrous cellulose dispersion]
Examples 1 to 64 and Comparative Examples 1 to 3 The obtained fine fibrous cellulose dispersions were diluted with ion-exchanged water so that the solid content concentration was 3% by mass. Next, defoaming treatment was performed with a rotation / revolution type super mixer (ARE-250 manufactured by Shinky Co., Ltd.). Then, the transparency of the dispersion was visually evaluated. As the evaluation criteria, the dispersion liquid was put into a glass cell, and a paper with 11-point characters was placed on one side, and the evaluation was made according to the following criteria.
A: The characters can be clearly read when viewed from the other side B: The characters are slightly blurred but the characters can be read C: The characters are blurred and the characters cannot be read, but the characters can be seen D: Cannot be deciphered at all

<Preparation of evaluation sheet>
Polyethylene oxide (PEO-3P, manufactured by Sumitomo Seika Chemical Co., Ltd.) was added to ion-exchanged water in an amount of 5% by mass, and the mixture was stirred and dissolved to obtain an aqueous polyethylene oxide solution. Next, the fine fibrous cellulose dispersions obtained in Examples 1 to 64 and Comparative Examples 1 to 3 and the above-mentioned polyethylene oxide aqueous solution were mixed with fine fibrous cellulose (solid content): polyethylene oxide (solid content) = 100 parts by mass: 20. The mixture was mixed so as to have a ratio of parts by mass. Further, in Examples 1 to 9, the solid content concentration was 2.5% by mass, in Examples 10 to 15, 22 to 38, 41, 43, 45, 47, 49, 51, and in Comparative Examples 1, 3 and 4, the solid content was solid. The concentration was 5% by mass, the solid content concentration was 10% by mass in Examples 16 to 21, 39, 40, 42, 44, 46, 48, 50, 52 to 64, and the solid content concentration was 1.5% by mass in Comparative Example 2. It was appropriately diluted with ion-exchanged water so as to be%, and used as a coating liquid. Next, the coating liquid is weighed so that the finished thickness of the obtained sheet (layer composed of the solid content of the coating liquid) is 40 μm, coated on a commercially available polycarbonate plate, and placed in a dryer at 100 ° C. It was dried for 30 minutes. A metal frame for damming (a gold frame having an inner dimension of 180 mm × 180 mm and a height of 5 cm) was arranged on the polycarbonate plate so as to have a predetermined basis weight. Next, the dried sheet was peeled off from the polycarbonate plate to obtain a fine fibrous cellulose-containing sheet.

[Sheet transparency evaluation]
The haze measurement of the obtained fine fibrous cellulose-containing sheet was measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7136: 2000.
The haze of the seat was judged according to the following criteria. When the haze of the sheet was less than 95%, it was determined that the transparency was good.
A: 0 or more and less than 5% B: 5% or more and less than 30% C: 30% or more and less than 95% D: 95% or more

[Evaluation of sheet curl]
The fine fibrous cellulose-containing sheet obtained by the above method was cut out so as to be a test piece having a width of 15 mm and a length of 130 mm. As shown in FIG. 1, the end including one short side of the test piece 50 is supported by a curl test jig 55 having a width of 30 mm, a length of 30 mm, and a height of 25 mm (a test piece having a length of 100 mm from the jig). Is exposed), the temperature is 23 ° C, and the relative humidity is 50%. On a horizontal table, the width direction of the test piece is perpendicular to the table (the longitudinal direction of the test piece is relative to the table). It was allowed to stand in parallel). Then, the curl width at the end of the test piece 50 was measured and used as the curl width C0 (distance of C0 in FIG. 1). After standing for 24 hours, the curl width was measured again and used as C1 (distance of C1 in FIG. 1), and C1-C0 was used as the curl amount.
The curl amount was judged according to the following criteria. When the curl amount was 25 mm or less, it was determined that the curl resistance was good.
A: 5 mm or less B: 5 mm or more 25 mm or less C: 25 mm or more

In the examples, a high-concentration fine fibrous cellulose dispersion was obtained, and a sheet in which curl was suppressed was formed from such a dispersion. It is considered that this is because the amount of water brought in can be reduced and the heat shrinkage during drying can be suppressed by forming the sheet from the high-concentration fine fibrous cellulose dispersion liquid. In Comparative Example 4, a uniform sample could not be prepared, and the viscosity and the like could not be measured.

50 Test piece 55 Test jig

Claims (7)

1. A dispersion containing fibrous cellulose having a fiber width of 1000 nm or less and having an ionic substituent.
   The content of the fibrous cellulose is 3.0% by mass or more with respect to the total mass of the dispersion liquid.
   The dispersion liquid in which the TI value of the dispersion liquid calculated according to the following condition (a) is 1 or more and 80,000 or less;
   Condition (a): Using a rheometer, the viscosity (η1) of the dispersion liquid under the condition of ^{a shear rate of 1 sec -1 and the viscosity (η2) of the dispersion liquid under the condition of a shear rate of 1000 sec -1} were measured, and the following formula was used. The TI value is calculated by.
   TI value = η1 / η2
2. The dispersion liquid according to claim 1, wherein the content of the fibrous cellulose is 4.0% by mass or more with respect to the total mass of the dispersion liquid.
3. The dispersion liquid according to claim 1, wherein the content of the fibrous cellulose is 5.0% by mass or more with respect to the total mass of the dispersion liquid.
4. The dispersion liquid according to claim 1, wherein the content of the fibrous cellulose is 6.0% by mass or more with respect to the total mass of the dispersion liquid.
5. The ionic substituent is at least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a sulfur oxo acid group and a substituent derived from a sulfur oxo acid group, claim 1. The dispersion liquid according to any one of 4 to 4.
6. The dispersion liquid according to any one of claims 1 to 5, wherein the haze is 95% or less when the dispersion liquid has a concentration of 0.2% by mass.
7. A sheet formed from the dispersion liquid according to any one of claims 1 to 6.

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