WO2020138156A1

WO2020138156A1 - Fibrous cellulose and method for producing fibrous cellulose

Info

Publication number: WO2020138156A1
Application number: PCT/JP2019/050803
Authority: WO
Inventors: 優作今村
Original assignee: 王子ホールディングス株式会社
Priority date: 2018-12-28
Filing date: 2019-12-25
Publication date: 2020-07-02
Also published as: JP2020105472A; JP6763423B2

Abstract

The present invention addresses the problem of providing a fibrous cellulose with which it is possible to increase the pH buffering properties in the neutral region of a dispersion liquid containing fibrous cellulose having a phosphorous acid group. The present invention relates to a fibrous cellulose in which a phosphorus oxoacid group includes a phosphoric acid group and a phosphorus acid group. In addition, the present invention relates to a method for producing a fibrous cellulose, the method including a step for mixing a cellulose raw material with a phosphoric acid group-containing compound and/or a salt thereof, a phosphorus acid group-containing compound and/or a salt thereof and urea and/or a urea derivative so as to obtain a cellulose raw material having a phosphoric acid group and a phosphorus acid group.

Description

Fibrous cellulose and method for producing fibrous cellulose

The present invention relates to fibrous cellulose and a method for producing fibrous cellulose.

Conventionally, cellulose fibers have been widely used in clothing, absorbent articles, paper products, etc. As 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 known. Fine fibrous cellulose has been attracting attention as a new material, and its uses are diverse. For example, the development of sheets, resin composites and thickeners containing fine fibrous cellulose is under way.

Fine fibrous cellulose can be manufactured by mechanically treating conventional cellulose fibers, but the cellulose fibers are strongly bonded by hydrogen bonding. Therefore, enormous energy is required to obtain fine fibrous cellulose simply by performing mechanical treatment. It is known that pretreatment such as chemical treatment or biological treatment is effective in addition to mechanical treatment in order to produce fine fibrous cellulose with smaller mechanical treatment energy. In particular, when a hydrophilic functional group (for example, a carboxy group, a cation group, a phosphate group, etc.) is introduced into the hydroxy group on the surface of cellulose by chemical treatment, electric repulsion between the ions occurs, and the ions are hydrated. By doing so, the dispersibility in an aqueous solvent is remarkably improved. Therefore, the energy efficiency of miniaturization is higher than that in the case where no chemical treatment is applied.

For example,

Patent Documents

1 and 2 disclose phosphorylated fine fibrous cellulose in which a phosphoric acid group forms an ester with a hydroxy group of cellulose. Further, Patent Document 3 discloses a cellulose fine fiber in which an ester of phosphorous acid is introduced into a part of hydroxy groups of the cellulose fiber, and a method for producing the same.

JP, 2005-189698, A International Publication No. 2014/185505 Japanese Patent Laid-Open No. 2018-141249

As mentioned above, fibrous cellulose having a phosphorus oxo acid group is known. Here, when the present inventors prepared an aqueous dispersion of fibrous cellulose having a phosphite group in a neutral region, the buffering property of pH is low, and the pH tends to largely fluctuate by the addition of acid or alkali. I found out that

Therefore, in order to solve the problems of the conventional art, the present inventors provide a fibrous cellulose containing a phosphite group, which can increase the pH buffering property in a neutral region. We proceeded with the study for the purpose.

As a result of intensive studies to solve the above problems, the present inventors have introduced both a phosphoric acid group and a phosphorous acid group into the fibrous cellulose, by which the fibrous cellulose having a phosphorous acid group. It was found that the pH of the contained dispersion can be enhanced in the neutral region.
Specifically, the present invention has the following configurations.

[1] Fibrous cellulose containing a phosphoric acid group and a phosphorous acid group.
[2] When the first dissociated acid amount in the fibrous cellulose is A1 and the total dissociated acid amount in the fibrous cellulose is A2, the value of A1/A2 is 0.51 or more and 0.97 or less, and A2 and A1 The fibrous cellulose according to [1], which has a difference of 0.04 mmol/g or more.
[3] A fibrous cellulose-containing material containing the fibrous cellulose according to [1] or [2].
[4] A compound having a phosphoric acid group and/or a salt thereof, a compound having a phosphorous acid group and/or a salt thereof, and urea and/or a urea derivative are mixed with a cellulose raw material to form a phosphoric acid group and A method for producing fibrous cellulose, which comprises the step of obtaining a cellulose raw material having a phosphite group.
[5] In the step of obtaining the cellulose raw material, the molar ratio of the compound having a phosphoric acid group and/or its salt to the compound having a phosphorous acid group and/or its salt is 0.01:99.99 to 99.99. : The method for producing fibrous cellulose according to [4], wherein the mixing is performed so as to be 0.01.

According to the present invention, in a fibrous cellulose-containing dispersion liquid having a phosphite group, it is possible to obtain fibrous cellulose capable of enhancing the pH buffering property in the neutral region.

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

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

(Fibrous cellulose)
The present invention relates to fibrous cellulose containing phosphoric acid groups and phosphorous acid groups. In the present specification, the phosphate group may be a substituent derived from the phosphate group. Further, the phosphorous acid group may be a substituent derived from the phosphorous acid group. That is, the fibrous cellulose of the present invention is a phosphoric acid group or a substituent derived from a phosphoric acid group (also simply referred to as a phosphoric acid group), and a phosphoric acid group or a substituent derived from a phosphorous acid group (simply Fibrous cellulose containing both (also referred to as phosphate groups).

Since the fibrous cellulose of the present invention has the above constitution, the pH buffering ability in the neutral region can be enhanced in the dispersion liquid containing the fibrous cellulose having a phosphite group. Specifically, even when an alkaline solution or an acid solution is added to the fibrous cellulose-containing dispersion liquid having a pH of around 7.0, the pH can be gently changed. Thereby, for example, in applications where fibrous cellulose is dispersed in neutral water and used as a dispersion, the stability of the fibrous cellulose-containing dispersion can be enhanced and the handling of the dispersion can be enhanced. Thus, the fibrous cellulose of the present invention is useful as a fibrous cellulose for water dispersion. The fibrous cellulose of the present invention can also be used for the purpose of dispersing it in a solvent other than water.

For example, the pH buffering capacity in the neutral region is such that when an alkaline solution is added to a fibrous cellulose-containing dispersion having a phosphite group having a pH of 6.5, the pH of the dispersion rises to 7.5. It can be evaluated by the amount of alkali required. It can be determined that the larger the amount of alkali necessary to raise the pH of the dispersion liquid in the neutral region by 1.0, the smaller the fluctuation of the pH and the higher the pH buffering capacity. Specifically, the amount of alkali (mmol) required to bring the fibrous cellulose-containing dispersion having a pH of 6.5 to pH 7.5 is divided by the fibrous cellulose (g) in the dispersion (mmol/ g) is preferably 0.03 mmol/g or more, more preferably 0.05 mmol/g or more, further preferably 0.10 mmol/g or more, and 0.14 mmol/g or more. Is particularly preferable.

Since the fibrous cellulose of the present invention has the above-mentioned constitution, it can exhibit excellent acid resistance. For example, when the pH of an aqueous dispersion of fibrous cellulose is lowered to acidic conditions, if the acid resistance of the fibrous cellulose is low, the viscosity of the dispersion under acidic conditions will be lower than the viscosity under neutral conditions. The transparency of the dispersion is lower than that under the neutral condition. On the other hand, when the acid resistance of the fibrous cellulose is high, the decrease in viscosity and transparency of the dispersion under acidic conditions is suppressed. In the present invention, even when the fibrous cellulose dispersion is subjected to acidic conditions, the decrease in viscosity and transparency is suppressed, and the fibrous cellulose exhibits excellent acid resistance.

Specifically, the haze (%) when the fibrous cellulose after the defibration treatment step was diluted with ion-exchanged water to a solid content concentration of 0.2% by mass was set to H0, and the fibrous cellulose was changed to hydrochloric acid. When the solid content concentration is 0.2 mass% with ion-exchanged water and the pH is 4.2 ± 0.2, the haze is H1, the solid content concentration is 0.2 mass%, and the pH is 2.7 ± 0.2. When the haze at that time is H2, the value of H1-H0 is preferably 1.0 or less, more preferably 0.8 or less, and further preferably 0.6 or less. The value of H1-H0 may be 0.0. Further, the value of H2-H0 is preferably 2.0 or less, more preferably 1.8 or less, and further preferably 1.6 or less. The value of H2-H0 may be 0.0. When the value of H1-H0 and/or the value of H2-H0 is within the above range, it can be determined that the acid resistance of the fibrous cellulose is excellent. The haze of the aqueous dispersion at each pH is measured according to JIS K 7136 after being diluted so that the solid content concentration becomes 0.2% by mass. A haze meter is used to measure the haze, and the dispersion liquid is filled in a glass cell for liquid having an optical path length of 1 cm. The zero point measurement is performed with ion-exchanged water contained in the glass cell.

In addition, the viscosity (mPa·s) when the fibrous cellulose after the defibration treatment step was diluted with ion-exchanged water to a solid content concentration of 0.2 mass% was set to ∨0, and the fibrous cellulose was changed to hydrochloric acid. When the solid content concentration is 0.2% by mass with ion-exchanged water and the pH is 4.2±0.2, the viscosity is V1, the solid content concentration is 0.2% by mass, and the pH is 2.7±0.2. When the viscosity at that time is V2, the value of ∨0−∨1 is preferably 5000 or less, more preferably 4000 or less, and further preferably 3000 or less. The value of ∨0−∨1 may be 0. Further, the value of ∨0−∨2 is preferably 9200 or less, and more preferably 9100 or less. The value of ∨0−∨2 may be 0. If the value of ∨0-∨1 and/or the value of ∨0-∨2 is within the above range, it can be judged that the acid resistance of the fibrous cellulose is excellent. The viscosity of the aqueous dispersion at each pH is such that after the solid content concentration is diluted to 0.2% by mass, the mixture is stirred at 1500 rpm with a disperser to make the slurry sufficiently uniform and at 23° C. and relative humidity. After standing in a 50% environment for 24 hours, measurement is performed using a B-type viscometer. The measurement condition is set to 23° C., the viscosity is measured for 30 seconds from the lapse of 2 minutes and 30 seconds to the end of the rotation (after 3 minutes) when rotating at 3 rpm for 3 minutes, and the average value is calculated. .. As the measuring device, a digital viscometer DV-2T manufactured by BLOOKFIELD can be used.

The fiber width of the fibrous cellulose of the present invention is not particularly limited and may be larger than 1000 nm or 1000 nm or less. In addition, fibrous cellulose having a fiber width of more than 1000 nm and fibrous cellulose having a fiber width of 1000 nm or less may be mixed. For example, when producing a slurry having excellent transparency, the fiber width of the fibrous cellulose is preferably 1000 nm or less, more preferably 100 nm or less, and further preferably 8 nm or less. In the present specification, fibrous cellulose having a fiber width of 1000 nm or less may be referred to as fine fibrous cellulose.

The fiber width of fibrous cellulose can be measured, for example, by observing with an electron microscope. The average fiber width of the fibrous cellulose may be greater than 1000 nm or 1000 nm or less. For example, when the average fiber width of the fibrous cellulose is greater than 1000 nm, it is preferably greater than 1 μm and less than or equal to 50 μm, more preferably greater than 1 μm and less than or equal to 40 μm, and even more preferably greater than 1 μm and less than or equal to 30 μm. .. When the average fiber width of the fibrous cellulose is 1000 nm or less, it is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more. Particularly preferably, it is 10 nm or less. The fibrous cellulose may be a single fibrous cellulose, but the fibrous cellulose in the present specification also includes a fiber assembly of single fibrous cellulose.

The average fiber width of the fibrous cellulose is measured, for example, using an electron microscope as follows. 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 the suspension is cast on a hydrophilized carbon film-covered grid to obtain a TEM observation sample. And When a wide fiber is included, an SEM image of the surface cast on glass may be observed. Then, observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times or 50000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification are adjusted so as to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary position in the observed image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The width of the fiber intersecting the straight line X and the straight line Y is visually read from the observed image satisfying the above conditions. In this way, at least three sets of observation images of surface portions that do not overlap each other are obtained. Then, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. Thereby, the fiber width of at least 20 fibers×2×3=120 fibers is read. Then, the average value of the read fiber width is set as the average fiber width of the fibrous cellulose.

The fiber length of the fibrous cellulose is not particularly limited, but when the fiber width is larger than 1000 nm, the fiber length is preferably 0.1 mm or more, and more preferably 0.6 mm or more. Further, the fiber length is preferably 50 mm or less, more preferably 20 mm or less. When the fiber width is 1000 nm or less, the fiber length is preferably 0.1 μm or more. The fiber length is preferably 1000 μm or less, more preferably 800 μm or less, and further preferably 600 μm or less. By setting the fiber length within the above range, breakage of the crystalline region of the fibrous cellulose can be suppressed. It is also possible to set the slurry viscosity of the fibrous cellulose within an appropriate range. The fiber length of the fibrous cellulose can be determined by image analysis using TEM, SEM, or AFM, for example.

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

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

The fibrous cellulose in this embodiment has both a crystalline region and an amorphous region, for example. In particular, fibrous cellulose having both a crystalline region and an amorphous region and a high axial ratio is realized by the method for producing fibrous cellulose described below.

The fibrous cellulose of the present invention has a phosphoric acid group and a phosphorous acid group. The introduction amount of the phosphorus oxo acid group (including the phosphoric acid group and the phosphorous acid group) in the fibrous cellulose is, for example, preferably 0.10 mmol/g or more, and 0.20 mmol/g per 1 g (mass) of the fibrous cellulose. More preferably, it is more preferably 0.50 mmol/g or more, still more preferably 1.00 mmol/g or more. Further, the introduction amount of the phosphorus oxo acid group in the fibrous cellulose is, for example, preferably 5.20 mmol/g or less per 1 g (mass) of the fibrous cellulose, more preferably 3.65 mmol/g or less. More preferably, it is not more than 00 mmol/g. Here, the unit mmol/g indicates the amount of the substituent per 1 g of the mass of the fibrous cellulose when the counter ion of the phosphorus oxo acid group is a hydrogen ion (H ⁺ ). Moreover, the said substituent amount is the total phosphorus oxo acid group amount containing a phosphoric acid group and a phosphorous acid group. By setting the introduction amount of the phosphorous acid group within the above range, the pH buffering ability in the neutral region can be more effectively increased in the dispersion liquid containing the fibrous cellulose having a phosphorous acid group. Furthermore, by setting the introduction amount of the phosphorus oxo acid group within the above range, the dispersibility of the fibrous cellulose in the solvent can be more effectively enhanced.

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

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

In the measurement of the amount of phosphorus oxo acid group by the titration method, an accurate value such as a lower amount of phosphorus oxo acid group than originally should be obtained when the amount of one drop of the aqueous sodium hydroxide solution is too large or the titration interval is too short. Sometimes you can't get it. Appropriate dropping amount and titration interval are, for example, titration of 0.1N sodium hydroxide aqueous solution at 10 to 50 μL every 5 to 30 seconds. In order to eliminate the influence of carbon dioxide dissolved in the fibrous cellulose-containing slurry, 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.

When the first dissociated acid amount (mmol/g) in the fibrous cellulose is A1 and the total dissociated acid amount (mmol/g) in the fibrous cellulose is A2, the value of A1/A2 is 0.51 or more. Is more preferable, 0.64 or more is more preferable, and 0.70 or more is still more preferable. The value of A1/A2 is preferably 0.97 or less, more preferably 0.8 or less, and further preferably 0.75 or less. Further, the difference between A2 and A1 is preferably 0.04 mmol/g or more, more preferably 0.2 mmol/g or more, and further preferably 0.4 mmol/g or more. The difference between A2 and A1 is preferably 1.5 mmol/g or less. Here, the first dissociated acid amount (A1) in the fibrous cellulose is the amount of alkali (mmol) required from the start of titration to the first end point in the titration curve described above, and the solid content (g) in the titration target slurry. ) Divided by. That is, the first dissociated acid amount (A1) is a value obtained by dividing the substance amount (mmol) of the acid ionized and neutralized in the first step by the solid content (g) in the titration target slurry. The total dissociated acid amount (A2) in the fibrous cellulose is a value obtained by dividing the amount of alkali (mmol) required from the start of titration to the second end point by the solid content (g) in the slurry to be titrated. That is, the total dissociated acid amount (A2) is a value obtained by dividing the substance amount (mmol) of all the acids that are ionized and neutralized in all stages by the solid content (g) in the titration target slurry. Therefore, as the value of A1/A2 is closer to 1, it means that the amount of weak acid (such as the amount of weakly acidic group in phosphorus oxo acid group) is smaller. Further, the larger the difference between A2 and A1, the larger the amount of the phosphate group introduced into the phosphite group. In the embodiment of the present invention, by setting A1 and A2 to values satisfying the above conditions, it is possible to obtain a preferable ratio for the introduction amount of the phosphoric acid group and the phosphorous acid group, and to adjust the pH buffer of the fibrous cellulose-containing dispersion liquid. Noh can be enhanced more effectively.

Note that the value of A1/A2 approaches 1 in both cases when the phosphoric acid group is condensed and when the phosphorous acid group is present. As a method for determining whether the factor that A1/A2 approaches 1 is due to the condensation of a phosphoric acid group or the presence of a phosphorous acid group, for example, a condensed structure of phosphoric acid such as acid hydrolysis is used. Examples include a method of performing the above-mentioned titration operation after the treatment of cutting, a method of performing the above-mentioned titration operation after the treatment of converting a phosphite group into a phosphate group such as an oxidation treatment.

Fibrous cellulose has both a phosphoric acid group and a phosphorous acid group as a phosphorus oxo acid group. Here, the phosphoric acid group may be a substituent derived from the phosphoric acid group, and the phosphorous acid group may be a substituent derived from the phosphorous acid group. The substituent derived from the phosphoric acid group may be a salt of a phosphoric acid group or a phosphoric acid ester group. Further, the substituent derived from the phosphorous acid group may be a salt of the phosphorous acid group.

Phosphonic acid group and phosphorous acid group may exist in the same cellulose molecular chain (cellulose monofilament). For example, of the two glucose units that are the basic structure that constitutes cellulose, one glucose may have a phosphate group introduced, and the other glucose unit may have a phosphite group introduced. Further, the fibrous cellulose of the present invention may be a fiber assembly of a cellulose molecular chain having a phosphoric acid group (cellulose single fiber) and a cellulose molecular chain having a phosphorous acid group (cellulose single fiber). The fibrous cellulose of the present invention includes a cellulose molecular chain having both a phosphoric acid group and a phosphorous acid group (cellulose single fiber), a cellulose molecular chain having a phosphoric acid group (cellulose single fiber), and phosphorous acid. It may be a fiber assembly of three types of single fibers of a cellulose molecular chain (cellulose single fiber) having a group.

In the present specification, the phosphoric acid group is, for example, a substituent represented by the following formula (1), and the phosphorous acid group is, for example, a substituent represented by the following formula (2).

In the formula (1), a and b are natural numbers, and m is an arbitrary number (however, a=b×m). a of α and α′ are O ⁻ , and the rest are OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. It is a hydrocarbon group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or a derivative group thereof. Note that α in the formula (1) may be a group derived from a cellulose molecular chain.

In the formula (2), b is a natural number, m is an arbitrary number, and b×m=1. α is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group , Unsaturated-cyclic hydrocarbon groups, aromatic groups, or derivatives thereof. Of these, α is particularly preferably a hydrogen atom. Note that α in the formula (2) does not include a group derived from a cellulose molecular chain.

Examples of the saturated-linear hydrocarbon group represented by α in formula (2) or R in formula (1) include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. However, it is not particularly limited. Examples of the saturated-branched hydrocarbon group include i-propyl group and t-butyl group, but are not particularly limited. Examples of the saturated-cyclic hydrocarbon group include a cyclopentyl group and a cyclohexyl group, but are not particularly limited. Examples of the unsaturated-straight chain hydrocarbon group include a vinyl group and an allyl group, but are not particularly limited. Examples of the unsaturated-branched hydrocarbon group include i-propenyl group and 3-butenyl group, but are not particularly limited. Examples of the unsaturated-cyclic hydrocarbon group include, but are not particularly limited to, cyclopentenyl group, cyclohexenyl group and the like. Examples of the aromatic group include a phenyl group and a naphthyl group, but are not particularly limited.

In addition, the α in the formula (2) or the derivative group in R in the formula (1) is a functional group such as a carboxy group, a hydroxy group, or an amino group with respect to the main chain or the side chain of the various hydrocarbon groups. Among these, at least one kind is a functional group in a state of being added or substituted, but 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, more preferably 10 or less. By adjusting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorous acid group can be adjusted to an appropriate range, and the permeability to the fiber raw material can be increased.

Β ^b+ in the formulas (1) and (2) is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or more cations composed of organic substances include aliphatic ammonium and aromatic ammonium, and examples of monovalent or more cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, or lithium, Examples thereof include cations of divalent metals such as calcium and magnesium, and hydrogen ions, but are not particularly limited. These may be applied alone or in combination of two or more. The cation having a valence of 1 or more consisting of an organic substance or an inorganic substance is preferably sodium or potassium ion which is less likely to be yellowed when a fiber raw material containing β is heated and which is industrially usable, but is not particularly limited.

The fibrous cellulose of the present invention may have a condensed phosphorus oxo acid group, and examples of the condensed phosphorus oxo acid group include a substituent represented by the following formula (3).

In the formula (3), a and b are natural numbers, m is an arbitrary number, and n is a natural number of 2 or more (however, a=b×m). Of α ¹ , α ² ,..., α ⁿ and α′, a is O ⁻ , and the rest is either R or OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. It is a hydrocarbon group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or a derivative group thereof. In addition, α in the formula (3) may be a group derived from a cellulose molecular chain.

Specific examples of each group in the formula (3) are the same as specific examples of each group in the formula (1), and specific examples of β ^b+ in the formula (3) are β in the formula (1). It is similar to the specific example of ^b+ .

The molar ratio of the substituent represented by the above formula (1) to the substituent represented by the above formula (2) among the phosphorous acid groups of the fibrous cellulose (formula (1): formula (2)) is , 0.01:99.99 to 99.99:0.01, preferably 1:99 to 99:1, and more preferably 10:90 to 90:10. That is, the molar ratio of the phosphoric acid group to the phosphorous acid group (phosphoric acid group:phosphorous acid group) in the phosphorous acid group of the fibrous cellulose is 0.01:99.99 to 99.99:0. It is preferably 01, more preferably 1:99 to 99:1, further preferably 10:90 to 90:10. By setting the molar ratio of the phosphoric acid group and the phosphorous acid group within the above range, in the fibrous cellulose-containing dispersion liquid having the phosphorous acid group, it is possible to more effectively enhance the pH buffering property in the neutral region. it can.

The fact that the fibrous cellulose has a phosphite group as a substituent means that the dispersion containing the fibrous cellulose was subjected to infrared absorption spectrum measurement, and phosphon which is a tautomer of the phosphite group was found around 1210 cm ^-1. It can be confirmed by observing absorption based on P=O of the acid group. In addition, the fact that the fibrous cellulose has a phosphate group as a substituent means that the dispersion containing the fibrous cellulose is subjected to infrared absorption spectrum measurement, and the absorption based on P=O of the phosphate group at 1230 cm ^{-1 is} measured. It can be confirmed by observing. Further, the fact that the fibrous cellulose has a phosphite group or a phosphate group as a substituent can be confirmed by a method of confirming a chemical shift using NMR, a method of combining titration with elemental analysis, or the like.

Note that the fibrous cellulose may have other anionic groups in addition to the phosphoric acid group and the phosphorous acid group. Examples of such an anionic group include a carboxy group originally contained in pulp.

(Method for producing fibrous cellulose)
The method for producing fibrous cellulose comprises mixing a cellulose raw material with a compound having a phosphoric acid group and/or a salt thereof, a compound having a phosphorous acid group and/or a salt thereof, and urea and/or a urea derivative. , A step of obtaining a cellulose raw material having a phosphoric acid group and a phosphorous acid group. In addition, below, the process of obtaining the cellulose raw material which has a phosphoric acid group and a phosphorous acid group is also called a phosphorus oxo acid group introduction process.

<Cellulose raw material>
Fibrous cellulose is manufactured from a fiber raw material (cellulose raw material) containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Pulps include, for example, wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, and examples thereof include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP) etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton-based pulp such as cotton linter and cotton lint, and non-wood-based pulp such as hemp, straw and bagasse. The deinked pulp is not particularly limited, and examples thereof include deinked pulp made from waste paper. The pulp of the present embodiment may be used alone or as a mixture of two or more kinds. Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of easy availability. Further, among the wood pulps, from the viewpoint of obtaining a long-fiber fibrous cellulose having a small decomposition of cellulose in the pulp and a large axial ratio, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable.

As the fiber raw material containing cellulose, for example, cellulose contained in ascidians or 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.

<Phosphorus oxo acid group introduction step>
In the phosphorus oxo acid group introduction step, a compound having a phosphoric acid group and/or a salt thereof, a compound having a phosphorous acid group and/or a salt thereof, and urea and/or a urea derivative are mixed with the cellulose raw material, In this step, a cellulose raw material having a phosphoric acid group and a phosphorous acid group is obtained. In the phosphorus oxo acid group introduction step, the hydroxyl group of the fiber raw material containing cellulose is reacted with the compound having a phosphoric acid group and/or its salt, and the compound having a phosphorous acid group and/or its salt to give phosphoric acid. Phosphorous acid groups, including groups and phosphorous acid groups, can be introduced. By this step, a cellulose raw material introduced with a phosphoric acid group and a phosphorous acid group can be obtained. In the present specification, a compound having a phosphoric acid group and/or a salt thereof, and a compound group including a compound having a phosphorous acid group and/or a salt thereof may be referred to as compound A, and urea and/or Alternatively, the urea derivative may be referred to as compound B.

An example of a method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B 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. Among these, it is preferable to use the fiber raw material in the dry state or the wet state, and particularly preferable to use the fiber raw material in the dry state, because the reaction is highly uniform. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. Compound A and compound B may be added to the fiber raw material in the form of powder or in the form of a solution dissolved in a solvent or in the state of being melted by heating to a melting point or higher. Of these, since the reaction is highly uniform, it is preferable to add them in the form of a solution dissolved in a solvent, particularly in the form of an aqueous solution. In addition, the compound A and the compound B may be added to the fiber raw material at the same time, separately, or as a mixture. The method of 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 dipped in the solution to absorb the liquid and then taken out. The solution may be added dropwise. Further, the required amounts of compound A and compound B may be added to the fiber raw material, or excess amounts of compound A and compound B may be respectively added to the fiber raw material, and then excess compound A and compound B may be squeezed or filtered. May be removed.

The compound A used in this embodiment includes at least a compound having a phosphoric acid group and/or a salt thereof, and a compound having a phosphorous acid group and/or a salt thereof. Examples of the compound having a phosphoric acid group include phosphoric acid, and phosphoric acid having various purities can be used. For example, 100% phosphoric acid (orthophosphoric acid) or 85% phosphoric acid is used. can do. Alternatively, phosphoric anhydride (diphosphorus pentoxide) may be used as the compound having a phosphoric acid group. Examples of the salt of the compound having a phosphoric acid group include a lithium salt, a sodium salt, a potassium salt, and an ammonium salt of phosphoric acid, which can have various degrees of neutralization. As the phosphoric acid, dehydrated condensed phosphoric acid obtained by condensing two or more molecules of phosphoric acid by a dehydration reaction (eg, pyrophosphoric acid, polyphosphoric acid, etc.) may be used. Examples of the compound having a phosphorous acid group include phosphorous acid, and examples of the phosphorous acid include 99% phosphorous acid (phosphonic acid). Examples of the salt of the compound having a phosphorous acid group include lithium salt, sodium salt, potassium salt, and ammonium salt of phosphorous acid, and these can have various degrees of neutralization. Of these, phosphoric acid and phosphorous acid are highly efficient in introducing phosphorus oxo acid groups, are more likely to be improved in defibration efficiency in the defibration step described later, are low in cost, and are easily industrially applicable. The sodium salt of phosphoric acid or phosphorous acid, the potassium salt of phosphoric acid or phosphorous acid, or the ammonium salt of phosphoric acid or phosphorous acid is preferably used.

The addition amount of the compound A to the fiber raw material is not particularly limited, but for example, when the addition amount of the compound A is converted into the phosphorus atomic weight, the addition amount of the phosphorus atom 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, still more preferably 2% by mass or more and 30% by mass or less. The addition amount of the compound A is the total addition amount of phosphoric acid and phosphorous acid. By setting the amount of phosphorus atoms added to the fiber raw material within the above range, the yield of fibrous cellulose can be further improved. On the other hand, by controlling the amount of phosphorus atoms added to the fiber raw material to be not more than the above upper limit, the effect of improving the yield and the cost can be balanced.

In the step of obtaining a cellulose raw material into which a phosphoric acid group and a phosphorous acid group are introduced, a compound having a phosphoric acid group and/or a salt thereof mixed as the compound A and a mole of a compound having a phosphorous acid group and/or a salt thereof are mixed. The ratio (phosphoric acid:phosphorous acid) is preferably 0.01:99.99 to 99.99:0.01, more preferably 1:99 to 99:1, and 10:90 to 90. More preferably, it is: 10. By setting the ratio of each compound to be mixed as the compound A within the above range, the pH buffering property in the neutral region can be more effectively enhanced in the fibrous cellulose-containing dispersion liquid having a phosphite group.

The compound B used in this embodiment is urea and/or a urea derivative as described above. Examples of the compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like. From the viewpoint of improving the homogeneity of the reaction, the compound B is preferably used as an aqueous solution. 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 the 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, more preferably 10% by mass or more and 400% by mass or less, More preferably, it is 100% by mass or more and 350% by mass or less.

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

In the phosphorus oxo acid group introduction step, it is preferable to heat-treat the fiber raw material after adding or mixing the compound A or the like to the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature at which the phosphorus oxo acid group can be efficiently introduced while suppressing thermal decomposition or 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. Further, for the heat treatment, equipment having various heat mediums can be used, for example, a stirring dryer, a rotary dryer, a disk dryer, a roll heater, a plate heater, a fluidized bed dryer, and an air stream. A drying device, a reduced pressure drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device can be used.

In the heat treatment according to the present embodiment, for example, a method of adding compound A to a thin sheet-shaped fiber raw material by a method such as impregnation and then heating, or heating while kneading or stirring the fiber raw material and compound A with a kneader or the like. Can be adopted. This makes it possible to suppress unevenness in the concentration of the compound A in the fiber raw material and more uniformly introduce the phosphorus oxo acid group to the surface of the cellulose fiber contained in the fiber raw material. This is because when 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 similarly moves to the surface of the fiber raw material (that is, uneven concentration of compound A It is thought to be due to the fact that it can be suppressed.

In addition, the heating device used for the heat treatment always keeps, for example, the water retained by the slurry and the water 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. An example of such a heating device is a blower type oven. By constantly discharging the water in the device system, in addition to suppressing the hydrolysis reaction of the phosphoric acid ester bond, which is the reverse reaction of phosphoric acid esterification, it is also possible to suppress the acid hydrolysis of sugar chains in the fiber. it can. Therefore, it becomes possible to obtain fibrous cellulose having a high axial ratio.

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

The phosphorus oxo acid group introduction step may be performed at least once, but can be repeated twice or more. By performing the phosphorus oxo acid group introduction step twice or more, many phosphorus oxo acid groups can be introduced into the fiber raw material. In the present embodiment, as an example of a preferable mode, a case where the phosphorus oxo acid group introduction step is performed twice is mentioned.

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

<Alkali treatment process>
In the case of producing fibrous cellulose, alkali treatment may be performed on the phosphorus oxo acid group-introduced fiber between the phosphorus oxo acid group introduction step and the defibration treatment step described below. The method of alkali treatment is not particularly limited, and examples thereof include a method of immersing the phosphoroxo acid group-introduced fiber in an alkali solution.

The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkaline compound or an organic alkaline compound. In this embodiment, for example, sodium hydroxide or potassium hydroxide is preferably used as the alkali compound because of its high versatility. 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 water or a polar solvent containing a polar organic solvent such as an 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 time for immersing the phosphorus oxo acid group-introduced fiber in the alkali 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 100000% by mass or less, and 1000% by mass or more and 10000% by mass or less, with respect to the absolutely dry mass of the phosphorus oxo acid group-introduced fiber. Is more preferable.

In order to reduce the amount of the alkaline solution used in the alkali treatment step, the phosphorus oxo acid group-introduced fiber may be washed with water or an organic solvent after the phosphorus oxo acid group 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 phosphorus oxo acid group-introduced fiber with water or an organic solvent from the viewpoint of improving the handling property.

<Acid treatment step>
In the case of producing fibrous cellulose, an acid treatment may be performed on the phosphorus oxo acid group-introduced fiber between the step of introducing the phosphorus oxo acid group and the defibration treatment step described later. For example, the phosphorus oxo acid group 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, but examples include a method of immersing the fiber raw material in an acid solution containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably 10% by mass or less, and more preferably 5% by mass or less. The pH of the 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 liquid, 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, chlorous 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, 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 100000% by mass or less, and 1000% by mass or more and 10000% by mass or less based on the absolute dry mass of the phosphorous acid group-introduced fiber. Is more preferable.

<Fibration process>
When producing fibrous cellulose having a fiber width of 1000 nm or less, the method for producing fibrous cellulose may include a defibration treatment step. In the defibration treatment step, a cellulose raw material having a phosphoric acid group and a phosphorous acid group (phosphorus oxo acid group-introduced fiber) is subjected to a refining treatment, and the fiber width is 1000 nm or less, and the phosphoric acid group and the phosphorous acid group are removed. This is a step of obtaining the fibrous cellulose possessed. In the defibration processing step, for example, a defibration processing device can be used. The defibration treatment device is not particularly limited, but includes, for example, a high-speed defibration machine, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultrahigh-pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disk refiner, a conical refiner, a twin screw A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, a beater, or the like can be used. Among the above defibration treatment devices, it is more preferable to use a high-speed defibration machine, a high-pressure homogenizer, or an ultrahigh-pressure homogenizer, which is less affected by the grinding media and less likely to cause contamination.

In the defibration processing step, for example, it is preferable to dilute the phosphorus oxo acid group-introduced fiber with a dispersion medium to form a slurry. As the dispersion medium, water and one or more selected from organic solvents such as polar organic solvents can be used. The polar organic solvent is not particularly limited, but alcohols, polyhydric alcohols, ketones, ethers, esters, aprotic polar solvents and the like are preferable. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol and glycerin. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, 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 solid content concentration of fine fibrous cellulose during defibration treatment can be set appropriately. Further, the slurry obtained by dispersing the phosphorus oxo acid group-introduced fibers in the dispersion medium may contain solid components other than the phosphorus oxo acid group introduced fibers such as urea having hydrogen bonding property.

(Containing fibrous cellulose)
The present invention may relate to a fibrous cellulose-containing material containing the above-mentioned fibrous cellulose. The fibrous cellulose-containing material preferably further contains a solvent and optional components as described below, in addition to the above-mentioned fibrous cellulose.

The solvent that can be contained in the fibrous cellulose-containing material includes water. Further, the solvent may be an organic solvent. Examples of the organic solvent include alcohols, polyhydric alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol and glycerin. Examples of ketones include acetone and methyl ethyl ketone. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, ethylene glycol mono t-butyl ether, and the like. The solvent may be a mixed solvent of water and an organic solvent.

The fibrous cellulose-containing material may be solid or gel, but is preferably liquid. When the fibrous cellulose-containing material is liquid, the fibrous cellulose-containing material may be a fibrous cellulose-containing slurry. When the fiber width of the fibrous cellulose is 1000 nm or less, the fine fibrous cellulose-containing slurry obtained in the defibration treatment step described above may be a fibrous cellulose-containing material. The fine fibrous cellulose-containing slurry may be concentrated or dried, and then redispersed in a solvent to obtain a fine fibrous cellulose-containing slurry. In this case, the redispersion liquid becomes a fibrous cellulose-containing substance.

When the fibrous cellulose-containing material is liquid, the fibrous cellulose-containing material is preferably a fibrous cellulose-containing slurry. The type of solvent constituting the fibrous cellulose-containing slurry is not particularly limited, but water, an organic solvent, or a mixture of water and an organic solvent can be mentioned. Examples of the organic solvent include the above-mentioned solvents.

The content of the fibrous cellulose based on the total mass of the fibrous cellulose-containing material is preferably 90% by mass or less, more preferably 70% by mass or less, further preferably less than 50% by mass, 30 It is more preferably not more than 10% by mass, particularly preferably not more than 10% by mass. The content of the fibrous cellulose with respect to the total mass of the fibrous cellulose-containing material is preferably 0.1% by mass or more.

When the fiber width of the fibrous cellulose is 1000 nm or less, the haze of the fine fibrous cellulose-containing slurry is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less. It is preferably 10% or less, and particularly preferably 10% or less. The haze of the fine fibrous cellulose-containing slurry may be 0%. The haze of the fine fibrous cellulose-containing slurry is measured according to JIS K 7136 after diluting it so that the solid content concentration of the fine fibrous cellulose-containing slurry is 0.2% by mass. A haze meter is used to measure the haze, and the dispersion liquid is filled in a glass cell for liquid having an optical path length of 1 cm. The zero point measurement is performed with ion-exchanged water contained in the glass cell.

When the fiber width of the fibrous cellulose is 1000 nm or less, the viscosity of the fine fibrous cellulose-containing slurry is preferably 1000 mPa·s or more, more preferably 2000 mPa·s or more, and 4000 mPa·s or more. Is more preferable. The upper limit of the viscosity of the fine fibrous cellulose-containing slurry is not particularly limited, but is preferably 40,000 mPa·s or less. The above-mentioned viscosity is obtained by diluting the fine fibrous cellulose-containing slurry so that the solid content concentration becomes 0.2% by mass, and then stirring at 1500 rpm with a disperser to make the slurry sufficiently uniform, and 23° C., relative. It is a value measured by using a B-type viscometer after standing for 24 hours in an environment of 50% humidity. The measurement conditions are set to 23° C., and the average value of the viscosity after 2 minutes and 30 seconds has elapsed and the rotation has been completed when rotating at 3 rpm for 3 minutes. As the measuring device, a digital viscometer DV-2T manufactured by BLOOKFIELD can be used.

<Arbitrary ingredients>
The fibrous cellulose-containing material may further contain optional components. Examples of the optional component include a defoaming agent, a lubricant, an ultraviolet absorber, a dye, a pigment, a stabilizer, a surfactant, and a preservative. In addition, the fibrous cellulose-containing slurry may contain a hydrophilic polymer, a hydrophilic low molecule, an organic ion, or the like as an optional component.

The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (excluding the above cellulose fiber), and examples of the oxygen-containing organic compound include polyethylene glycol, polyethylene oxide, casein, dextrin, starch, and modified Starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylic acid salts, alkyl acrylate copolymers, urethane copolymers, cellulose derivatives (hydroxyethyl cellulose, carboxy) Ethyl cellulose, carboxymethyl cellulose, etc.) and the like.

The hydrophilic low-molecular weight compound 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.

The organic ions 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, cetyl trimethyl ammonium ion, stearyl trimethyl ammonium ion, octyl dimethyl ethyl ammonium ion, lauryl dimethyl ethyl ammonium ion, didecyl dimethyl ammonium ion, lauryl dimethyl benzyl ammonium ion, and tributyl benzyl ammonium ion. Examples of the tetraalkylphosphonium ion include tetramethylphosphonium ion, tetraethylphosphonium ion, tetrapropylphosphonium ion, tetrabutylphosphonium ion, and lauryltrimethylphosphonium ion. Further, as tetrapropylonium ion and tetrabutylonium ion, tetra n-propyl onium ion, tetra n-butyl onium ion and the like can be mentioned, respectively.

(Molded body)
The present invention may relate to the above-mentioned fibrous cellulose or a molded product formed from the above-mentioned fibrous cellulose-containing material. In the present specification, the term “molded product” refers to a solid product molded into a desired shape or a solid product formed into a sheet. Examples of the molded body include sheets (including paper), beads, filaments, and the like. Among them, the molded body is preferably a sheet, beads or filament. When the molded product is in the form of beads, the particle diameter of the beads is preferably 0.1 mm or more and 10 mm or less. When the molded product is in the form of filament, the width of the filament is preferably 0.1 mm or more and 10 mm or less, and the length of the filament is preferably 1 mm or more and 10000 mm or less.

Above all, the molded body is preferably a sheet. When the molded product is a sheet, the thickness of the sheet is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more. The upper limit of the thickness of the sheet is not particularly limited, but can be set to 1000 μm, for example. The thickness of the sheet can be measured by, for example, a stylus thickness meter (Millitron 1202D, manufactured by Marl).

The sheet may be paper if the fiber width of the fibrous cellulose is greater than 1000 nm. Further, the sheet may be a non-woven fabric. Such a sheet or nonwoven fabric may be used as a constituent member of various hygienic papers or absorbent articles.

If the fiber width of the fibrous cellulose is 1000 nm or less, the sheet may be a highly transparent sheet. In such a case, the haze of the sheet is, for example, preferably 2% or less, more preferably 1.5% or less, and further preferably 1% or less. On the other hand, the lower limit of the haze of the sheet is not particularly limited and may be 0%, for example. Here, the haze of the sheet is a value measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136, for example.

The total light transmittance of the sheet is, for example, preferably 85% or more, more preferably 90% or more, and further preferably 91% or more. On the other hand, the upper limit of the total light transmittance of the sheet is not particularly limited and may be 100%, for example. Here, the total light transmittance of the sheet is a value measured by using a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K7361.

The basis weight of the sheet is not particularly limited, but is preferably 10 g/m ² or more, more preferably 20 g/m ² or more, and further preferably 30 g/m ² or more. The basis weight of the sheet is not particularly limited, but is preferably 200 g/m ² or less, and more preferably 180 g/m ² or less. Here, the basis weight of the sheet can be calculated in accordance with JIS P 8124, for example.

The density of the sheet is not particularly limited, but is preferably 0.1 g/cm ³ or more, more preferably 0.5 g/cm ³ or more, and further preferably 1.0 g/cm ³ or more. preferable. The density of the sheet is not particularly limited, but is preferably 5.0 g/cm ³ or less, and more preferably 3.0 g/cm ³ or less. Here, the density of the sheet can be calculated by measuring the thickness and mass of the sheet after conditioning the 50 mm square sheet at 23° C. and 50% relative humidity for 24 hours.

The content of fibrous cellulose in the sheet is, for example, preferably 0.5% by mass or more, more preferably 1% by mass or more, and more preferably 5% by mass or more, based on the total mass of the sheet. Is more preferable and 10% by mass or more is particularly preferable. On the other hand, the upper limit of the content of fibrous cellulose in the sheet is not particularly limited, and may be 100% by mass or 95% by mass with respect to the total mass of the sheet.

The sheet may include optional components that can be included in the fibrous cellulose-containing slurry. Further, the sheet may contain water or an organic solvent.

(Method for producing sheet containing fibrous cellulose)
When the molded body is a sheet, the method for producing a fibrous cellulose-containing sheet includes a coating step of coating a fibrous cellulose-containing slurry on a substrate, or a papermaking step of papermaking the slurry, as described below. It is preferable.

<Coating process>
In the coating step, for example, a fibrous cellulose-containing slurry (hereinafter, also simply referred to as a slurry) is coated on a base material, and a sheet formed by drying this is peeled from the base material to obtain a sheet. it can. Moreover, a sheet can be continuously produced by using a coating device and a long base material.

The material of the base material used in the coating step is not particularly limited, but a material having higher wettability with the fibrous cellulose-containing slurry (slurry) may be able to suppress shrinkage of the sheet during drying, etc. It is preferable to select a sheet from which the sheet formed later can be easily peeled off. Of these, a resin film or plate or a metal film or plate is preferable, but not particularly limited. For example, resin films and plates of polypropylene, acrylic, polyethylene terephthalate, vinyl chloride, polystyrene, polycarbonate, polyvinylidene chloride, etc., metal films and plates of aluminum, zinc, copper, iron plates, and those whose surfaces are oxidized. A stainless film or plate, a brass film or plate, or the like can be used.

When the viscosity of the slurry is low in the coating process and spreads on the base material, use a damming frame fixed on the base material to obtain a sheet with a predetermined thickness and basis weight. May be. The damming frame is not particularly limited, but it is preferable to select, for example, a frame that allows the edges of the sheet attached after drying to be easily peeled off. From this point of view, a molded resin plate or metal plate is more preferable. In the present embodiment, for example, a polypropylene plate, an acrylic plate, a polyethylene terephthalate plate, a vinyl chloride plate, a polystyrene plate, a polycarbonate plate, a polyvinylidene chloride plate, or another resin plate, or an aluminum plate, a zinc plate, a copper plate, an iron plate, or another metal plate. It is also possible to use those obtained by subjecting the surfaces thereof to an oxidation treatment, molded stainless steel plates, brass plates and the like. The coating machine for coating the slurry on the substrate is not particularly limited, but for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater or the like can be used. A die coater, a curtain coater, and a spray coater are particularly preferable because the thickness of the sheet can be made more uniform.

The slurry temperature and the ambient temperature when the slurry is applied to the substrate are not particularly limited, but are preferably 5° C. or higher and 80° C. or lower, more preferably 10° C. or higher and 60° C. or lower, and 15° C. The temperature is more preferably 50°C or higher and particularly preferably 20°C or higher and 40°C or lower. If the coating temperature is at least the above lower limit, the slurry can be coated more easily. If the coating temperature is at most the above upper limit, volatilization of the dispersion medium during coating can be suppressed.

In the coating step, the slurry is used so that the finished basis weight of the sheet is preferably 10 g/m ² or more and 200 g/m ² or less, more preferably 20 g/m ² or more and 180 g/m ² or less. It is preferable to coat the material. By coating so that the basis weight is within the above range, a sheet having excellent strength can be obtained.

The coating step includes a step of drying the slurry coated on the base material as described above. The step of drying the slurry is not particularly limited, but is performed by, for example, a non-contact drying method, a method of drying while restraining the sheet, or a combination thereof.

The non-contact drying method is not particularly limited, but for example, a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heating drying method) or a method of drying in vacuum (vacuum drying method) is applied. can do. The heat drying method and the vacuum drying method may be combined, but the heat drying method is usually applied. Drying with infrared rays, far infrared rays, or near infrared rays is not particularly limited, but can be performed using, for example, an infrared device, a far infrared device, or a near infrared device.

The heating temperature in the heating and drying method is not particularly limited, but is preferably 20° C. or higher and 150° C. or lower, and more preferably 25° C. or higher and 105° C. or lower. When the heating temperature is at least the above lower limit, the dispersion medium can be volatilized quickly. When the heating temperature is at most the above upper limit, it is possible to suppress the cost required for heating and suppress the discoloration of fibrous cellulose due to heat.

<Papermaking process>
The papermaking process is performed by making a slurry from a papermaking machine. The paper machine used in the paper making step is not particularly limited, and examples thereof include a fourdrinier type, cylinder type, inclined type and the like continuous paper machine, and a multi-layered paper machine combining these. In the paper making step, a known paper making method such as hand making may be adopted.

The papermaking process is performed by filtering the slurry with a wire and dehydrating it to obtain a wet paper sheet, and then pressing and drying this sheet. The filter cloth used for filtering and dehydrating the slurry is not particularly limited, but it is more preferable that, for example, fibrous cellulose does not pass through and the filtration rate does not become too slow. The filter cloth is not particularly limited, but a sheet, a woven fabric, and a porous membrane made of an organic polymer are preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene and polytetrafluoroethylene (PTFE) are preferable. In the present embodiment, for example, a polytetrafluoroethylene porous film having a pore diameter of 0.1 μm or more and 20 μm or less, a polyethylene terephthalate or polyethylene woven fabric having a pore diameter of 0.1 μm or more and 20 μm or less, and the like can be mentioned.

In the sheet-forming step, a method for producing a sheet from the slurry includes, for example, discharging a slurry containing fibrous cellulose onto the upper surface of an endless belt, and squeezing a dispersion medium from the discharged slurry to form a web. , A drying section for drying the web to produce a sheet. An endless belt is arranged from the water squeezing section to the drying section, and the web produced in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

The dehydration method used in the papermaking process is not particularly limited, and examples thereof include the dehydration method commonly used in paper production. Among these, a method of dehydrating with a Fourdrinier, a cylinder, an inclined wire or the like, and then further dehydrating with a roll press is preferable. The drying method used in the papermaking step is not particularly limited, and examples thereof include the method used in the production of paper. Among these, a drying method using a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, an infrared heater or the like is more preferable.

(Use)
The fibrous cellulose of the present invention can be used as a thickener or a particle dispersion stabilizer. Further, by mixing the fibrous cellulose of the present invention with a solvent, a fibrous cellulose-containing slurry or a sheet in which the fibrous cellulose is uniformly dispersed can be formed. Further, the fibrous cellulose of the present invention can be preferably used for mixing with an organic solvent containing a resin component. By mixing the fibrous cellulose of the present invention and an organic solvent containing a resin component, a resin composite in which the fibrous cellulose is uniformly dispersed can be formed. Similarly, a fibrous cellulose redispersion slurry is used to form a film, which can be used as various films.

Further, the fibrous cellulose of the present invention can be used as a reinforcing agent or an additive in cement, paint, ink, lubricant and the like. A molded product obtained by coating fibrous cellulose on a base material is a reinforcing material, interior material, exterior material, packaging material, electronic material, optical material, acoustic material, process material, member of transportation equipment. It is also suitable for applications such as electronic equipment members and electrochemical element members.

The features of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following specific examples.

<Production Example 1>
As a raw material pulp, a softwood kraft pulp made by Oji Paper Co., Ltd. (solid content 93 mass %, basis weight 245 g/m ² sheet shape, Canadian standard freeness (CSF) measured in accordance with JIS P 8121 is 700 ml) It was used.

Phosphono oxidation treatment was performed on this raw material pulp as follows. First, a mixed aqueous solution of phosphoric acid, phosphorous acid (phosphonic acid) and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to give 28.5 parts by mass of phosphoric acid and phosphorous acid (phosphonic acid). 7.9 parts by mass, 120 parts by mass of urea and 150 parts by mass of water were prepared to obtain a chemical solution-impregnated pulp. Then, the obtained chemical-solution-impregnated pulp was heated for 250 seconds with a hot air dryer at 165° C. to introduce phosphorus oxo acid groups into the cellulose in the pulp to obtain phosphorus oxo oxidized pulp.

Next, the phosphorous oxidative pulp obtained was subjected to a cleaning treatment. The washing treatment is carried out by repeating the operation of filtering and dehydrating the pulp dispersion obtained by pouring 10 L of ion-exchanged water to 100 g of phosphorus oxo-oxidized pulp (absolutely dry mass), stirring the mixture to uniformly disperse the pulp, and then filtering. went. When the electric conductivity of the filtrate became 100 μS/cm or less, the washing end point was set.

Next, the washed phosphorous oxoxidized pulp was neutralized as follows. First, the washed phosphorous oxide pulp was diluted with 10 L of ion-exchanged water, and 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorous oxide pulp slurry having a pH of 12 or more and 13 or less. .. Then, the phosphorous oxide pulp slurry was dehydrated to obtain a neutralized phosphorous oxide pulp. Next, the above-mentioned washing treatment was performed on the phosphorus-oxo-oxidized pulp after the neutralization treatment to obtain phosphorus-oxo-oxidized pulp (neutralized).

Ion-exchanged water was added to the obtained phosphorus oxo-oxidized pulp (neutralized), and the mixture was stirred to form a slurry having a solid content concentration of 0.3% by mass. This slurry was treated 3 times under the condition of 150 MPa using a high-pressure homogenizer (Beryu MINI, manufactured by Bijin Co., Ltd.) to obtain a fibrous cellulose-containing slurry.

<Production Example 2>
In the mixed aqueous solution of phosphoric acid, phosphorous acid and urea, the addition amount of phosphoric acid and phosphorous acid (phosphonic acid) was changed to 19.0 parts by mass of phosphoric acid and 15.9 parts by mass of phosphorous acid (phosphonic acid). Except for the above, in the same manner as in Production Example 1, a phosphoroxoxidized pulp (neutralized) and a fibrous cellulose-containing slurry were obtained.

<Production Example 3>
In the mixed aqueous solution of phosphoric acid, phosphorous acid and urea, the addition amount of phosphoric acid and phosphorous acid (phosphonic acid) was changed to 9.5 parts by mass of phosphoric acid and 23.8 parts by mass of phosphorous acid (phosphonic acid). Except for the above, in the same manner as in Production Example 1, a phosphoroxoxidized pulp (neutralized) and a fibrous cellulose-containing slurry were obtained.

<Production Example 4>
In the mixed aqueous solution of phosphoric acid, phosphorous acid and urea, the addition amount of phosphoric acid and phosphorous acid (phosphonic acid) was changed to 1.1 parts by mass of phosphoric acid and 30.8 parts by mass of phosphorous acid (phosphonic acid). Except for the above, in the same manner as in Production Example 1, a phosphoroxoxidized pulp (neutralized) and a fibrous cellulose-containing slurry were obtained.

<Production Example 5>
In a mixed aqueous solution of phosphoric acid, phosphorous acid and urea, phosphorous acid was added in the same manner as in Production Example 1 except that the amount of phosphoric acid was changed to 37.9 parts by mass and phosphorous acid was not added. (Neutralized) and fibrous cellulose-containing slurries were obtained.

<Production Example 6>
In a mixed aqueous solution of phosphoric acid, phosphorous acid, and urea, phosphorous acid was added in the same manner as in Production Example 1 except that the amount of phosphorous acid was changed to 31.7 parts by mass and phosphoric acid was not added. (Neutralized) and fibrous cellulose-containing slurries were obtained.

<Measurement of infrared absorption spectrum>
Infrared absorption spectra of the phosphorus oxo-oxidized pulp (neutralized) and fine fibrous cellulose obtained in Production Examples 1 to 6 were measured by FT-IR. As a result, in the phosphoroxoxidized pulp (neutralized) and fine fibrous cellulose obtained in Production Examples 1 to 3 and Production Example 5, absorption based on P=O of the phosphate group was observed at around 1230 cm ^-1 , It was confirmed that the phosphoric acid group was added to. Further, in Production Examples 1 to 4 and Production Example 6, absorption based on P=O of the phosphonic acid group, which is a tautomer of the phosphite group, was observed at around 1210 cm ^-1 , and the phosphite group ( It was confirmed that a phosphonic acid group) was added.

<X-ray diffraction analysis>
The phosphorus oxo-oxidized pulp (neutralized) obtained in Production Examples 1 to 6 was tested and analyzed by an X-ray diffractometer. The results were 2θ=14° or more and 17° or less and 2θ=22° or more 23 Typical peaks were confirmed at two positions in the vicinity of ° or less, and it was confirmed to have a cellulose type I crystal. It was also confirmed that the fine fibrous celluloses obtained in Production Examples 1 to 6 maintained the cellulose type I crystals. The fiber width of the fine fibrous cellulose was measured with a transmission electron microscope, and it was 3 to 5 nm.

<Example 1>
With respect to the fibrous cellulose-containing slurry obtained in Production Example 1, the amount of first dissociated acid and the total amount of dissociated acid introduced into cellulose were measured by the method described below. Further, the pH buffering ability in the neutral region was evaluated by the method described below.

<Example 2>
Regarding the fibrous cellulose-containing slurry obtained in Production Example 2, the first dissociated acid amount introduced into cellulose, the total dissociated acid amount, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. The fibrous cellulose-containing slurry obtained in Production Example 2 was diluted with ion-exchanged water to 0.2% by mass, and the haze and viscosity were measured by the methods described below. Furthermore, the pH of the fibrous cellulose-containing slurry obtained in Production Example 2 was adjusted with 1N hydrochloric acid and diluted with ion-exchanged water to 0.2% by mass to adjust the pH to 4.2±0.2. And a slurry having a pH of 2.7±0.2 were obtained. The haze and viscosity of these slurries were also measured by the methods described below.

<Example 3>
Regarding the fibrous cellulose-containing slurry obtained in Production Example 3, the first dissociated acid amount introduced into cellulose, the total dissociated acid amount, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. Further, the haze and viscosity of the fibrous cellulose-containing slurry obtained in Production Example 3 were measured in the same manner as in Example 2.

<Example 4>
Regarding the fibrous cellulose-containing slurry obtained in Production Example 4, the first dissociated acid amount introduced into cellulose, the total dissociated acid amount and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. Further, the haze and the viscosity of the fibrous cellulose-containing slurry obtained in Production Example 4 were measured in the same manner as in Example 2.

<Example 5>
The fibrous cellulose-containing slurry obtained in Production Example 5 and the fibrous cellulose-containing slurry obtained in Production Example 6 were mixed so that the mass of the fibrous cellulose was 1:1 to obtain the fibrous cellulose-containing slurry of Example 5. It was made into a slurry. With respect to this fibrous cellulose-containing slurry, the first dissociated acid amount introduced into cellulose, the total dissociated acid amount, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. Further, with regard to the fibrous cellulose-containing slurry of Example 5, the haze and the viscosity were measured in the same manner as in Example 2.

<Example 6>
Regarding the fibrous cellulose-containing slurry obtained in Production Example 6, the amount of first dissociated acid introduced into cellulose, the amount of total dissociated acid, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1.

<Example 7>
The fibrous cellulose-containing slurry obtained in Production Example 5 was measured for haze and viscosity in the same manner as in Example 2.

<Measurement method>
<Measurement of first dissociated acid amount and total dissociated acid amount>
The first dissociated acid amount and the total dissociated acid amount were measured by the neutralization titration method. Specifically, a fibrous cellulose-containing slurry prepared by diluting a fibrous cellulose dispersion liquid containing fibrous cellulose with ion-exchanged water to a content of 0.2 mass% is prepared by using an ion-exchange resin. After the treatment, it was measured by performing titration with alkali.
The treatment with an ion exchange resin was carried out by adding 1/10 by volume of a strongly acidic ion exchange resin (Amber Jet 1024; Organo Co., Ltd., already conditioned) to the above fibrous cellulose-containing slurry and performing a shaking treatment for 1 hour. , And the resin and the slurry were separated by pouring onto a mesh having an opening of 90 μm.
In addition, titration using an alkali measures the change in the pH value of the slurry while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after the treatment with the ion exchange resin every 5 seconds. It was done by doing. The titration was performed 15 minutes before the start of titration while blowing nitrogen gas into the slurry. In this neutralization titration, two points at which the increment (the differential value of pH with respect to the amount of alkali added) is maximized are observed in the curve plotting the pH measured against the amount of alkali added. Of these, the maximum point of the increment obtained first after adding alkali is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 1). The amount of alkali required from the start of titration to the first end point becomes 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. A value obtained by dividing the alkali amount (mmol) required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated was defined as the first dissociated acid amount (mmol/g). A value obtained by dividing the amount of alkali (mmol) required from the start of titration to the second end point by the solid content (g) in the slurry to be titrated was taken as the total dissociated acid amount (mmol/g).

<Evaluation of pH buffering capacity in neutral range>
Nitrogen gas was blown for 15 minutes into the slurry containing fibrous cellulose in which the phosphorus oxo acid group was converted to the acid form through the treatment step with the ion exchange resin in <Measurement of the first dissociated acid amount and total dissociated acid amount>. , 0.1N sodium hydroxide solution was added to adjust the pH of the slurry to 6.5. Further, 0.1N sodium hydroxide solution was added to adjust the pH of the slurry to 7.5. The value (mmol/g) obtained by dividing the amount of alkali required to bring the pH 6.5 slurry to pH 7.5 by the solid content (g) in the slurry was recorded and evaluated as the pH buffering capacity in the neutral region. did.

<Method of measuring haze of slurry containing fibrous cellulose>
Haze is a measure of the transparency of the fibrous cellulose-containing slurry, and the lower the haze value, the higher the transparency. The haze was measured by diluting the fibrous cellulose-containing slurry so that the solid content concentration was 0.2% by mass, and then using a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) with an optical path length of 1 cm. It was measured according to JIS K 7136 using a glass cell for liquid (manufactured by Fujiwara, MG-40, reverse optical path). The zero point measurement was performed with ion-exchanged water contained in the glass cell.

<Viscosity measuring method of slurry containing fibrous cellulose>
Regarding the viscosity of the fibrous cellulose-containing slurry, after diluting so that the solid content concentration of the fibrous cellulose-containing slurry was 0.2% by mass, the slurry was stirred at 1500 rpm with a disperser to make the slurry sufficiently uniform. The obtained slurry was allowed to stand in an environment of 23° C. and 50% relative humidity for 24 hours, and then the viscosity of the slurry was measured using a B-type viscometer (Digital Viscometer DV-2T manufactured by BLOOKFIELD). The measurement condition was set to 23° C., and the viscosity was measured for 30 seconds from the lapse of 2 minutes and 30 seconds to the end of rotation (after 3 minutes) when rotating at 3 rpm for 3 minutes, and the average value was calculated. ..

In Examples 1 to 5, it was confirmed that the pH buffering capacity in the neutral region was high. In addition, in Examples 2 to 5, the values of H1-H0 and H2-H0 were smaller than in Example 7, and the increase in haze was small even under acidic conditions. Further, in Examples 2 to 5, the values of ∨0-∨1 and ∨0-∨2 were smaller than those of Example 7, and the decrease in viscosity was small even under acidic conditions. The same tendency was observed in Example 1. Thus, in Examples 1 to 5, it was confirmed that the acid resistance was also excellent.

Claims

Fibrous cellulose containing phosphoric acid groups and phosphorous acid groups.
When the first dissociated acid amount in the fibrous cellulose is A1 and the total dissociated acid amount in the fibrous cellulose is A2, the value of A1/A2 is 0.51 or more and 0.97 or less, and The fibrous cellulose according to claim 1, wherein the difference is 0.04 mmol/g or more.
A fibrous cellulose-containing material containing the fibrous cellulose according to claim 1 or 2.
The cellulose raw material is mixed with a compound having a phosphoric acid group and/or a salt thereof, a compound having a phosphorous acid group and/or a salt thereof, and urea and/or a urea derivative to form a phosphoric acid group and phosphorous acid. A method for producing fibrous cellulose, which comprises the step of obtaining a cellulose raw material having a group.
In the step of obtaining the cellulose raw material, the molar ratio of the compound having a phosphoric acid group and/or a salt thereof to the compound having a phosphorous acid group and/or a salt thereof is 0.01:99.99 to 99.99:0. The method for producing fibrous cellulose according to claim 4, wherein the mixing is carried out so as to be 0.01.