JP2020152926A - Fibrous cellulose and method for manufacturing the same - Google Patents

Abstract

To provide fibrous cellulose capable of enhancing pH buffering properties in a neutral region in a fibrous cellulose containing dispersion having a phosphorous acid group.SOLUTION: A phosphorus oxo acid group relates to fibrous cellulose including a phosphate group and a phosphorous acid group. The method for manufacturing the fibrous cellulose includes the step of mixing a compound having a phosphate group and/or a salt thereof, a compound having a phosphorous acid group and/or a salt thereof and urea and/or an urea derivative with a cellulose raw material to obtain a cellulose raw material having the phosphate group and the phosphorous acid group.SELECTED DRAWING: None

Description

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 and the like. As the cellulose fibers, in addition to fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Fine fibrous cellulose is attracting attention as a new material, and its uses are diverse. For example, development of sheets containing fine fibrous cellulose, resin composites, and thickeners is underway.

Fine fibrous cellulose can be produced by mechanically treating conventional cellulose fibers, but the cellulose fibers are strongly bonded to each other by hydrogen bonds. Therefore, a huge amount of energy is required to obtain fine fibrous cellulose by simply performing mechanical treatment. It is known that in order to produce fine fibrous cellulose with smaller mechanical processing energy, it is effective to perform pretreatment such as chemical treatment and biological treatment in addition to mechanical treatment. In particular, when a hydrophilic functional group (for example, a carboxy group, a cation group, a phosphoric acid group, etc.) is introduced into a hydroxy group on the surface of cellulose by chemical treatment, electrical repulsion between 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 performed.

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 the hydroxy group of the cellulose fiber, and a method for producing the same.

Japanese Unexamined Patent Publication No. 2015-189698 International Publication No. 2014/185505 JP-A-2018-141249

As described 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 phosphorous acid group in the neutral region, the pH buffering property was low, and the pH tended to fluctuate greatly due to the addition of acid or alkali. It turned out to be in.

Therefore, in order to solve the problems of the prior art, the present inventors provide fibrous cellulose capable of enhancing the buffering property of pH in the neutral region in the fibrous cellulose-containing dispersion having a phosphorous acid group. We proceeded with the study for the purpose of doing so.

As a result of diligent studies to solve the above problems, the present inventors have introduced fibrous cellulose having a phosphite group by introducing both a phosphoric acid group and a phosphite group into the fibrous cellulose. It has been found that in the containing dispersion, the buffering property of pH in the neutral region can be enhanced.
Specifically, the present invention has the following configuration.

[1] Fibrous cellulose containing a phosphoric acid group and a phosphorous acid group.
[2] When the amount of the first dissociating acid in the fibrous cellulose is A1 and the total amount of the dissociating acid in the fibrous cellulose is A2, the values of A1 / A2 are 0.51 or more and 0.97 or less, and A2 and A1. The fibrous cellulose according to [1], wherein the difference between the two is 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 a urea and / or a urea derivative are mixed with a cellulose raw material to obtain a phosphoric acid group and / or a salt thereof. A method for producing fibrous cellulose, which comprises a step of obtaining a cellulose raw material having a phosphorous acid 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], which is mixed so as to be 0.01.

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

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

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

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

Since the fibrous cellulose of the present invention has the above-mentioned structure, it is possible to enhance the pH buffering ability in the neutral region in the dispersion liquid containing the fibrous cellulose having a phosphorous acid group. Specifically, even when an alkaline solution or an acid solution is added to the fibrous cellulose-containing dispersion having a pH of around 7.0, the fluctuation of the pH can be made gentle. Thereby, for example, in an application in which fibrous cellulose is dispersed in neutral water and used as a dispersion liquid, the stability of the fibrous cellulose-containing dispersion liquid can be improved, and the ease of handling of the dispersion liquid can be improved. As described above, 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 dispersing in a solvent other than water.

For example, the pH buffering capacity in the neutral region increases to 7.5 when an alkaline solution is added to a fibrous cellulose-containing dispersion having a phosphite group with a pH of 6.5. It can be evaluated by the amount of alkali required for. It can be determined that the larger the amount of alkali required to raise the pH of the dispersion in the neutral region by 1.0, the smaller the fluctuation in pH and the higher the pH buffering capacity. Specifically, the amount of alkali (mmol) required to bring the pH 6.5 fibrous cellulose-containing dispersion to pH 7.5 is divided by the fibrous cellulose (g) in the dispersion (mmol / 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 preferred.

Further, since the fibrous cellulose of the present invention has the above-mentioned structure, it can exhibit excellent acid resistance. For example, when the pH of the aqueous dispersion of fibrous cellulose is lowered to an acidic condition, if the acid resistance of the fibrous cellulose is low, the viscosity of the dispersion under acidic conditions is lower than the viscosity under neutral conditions, and the acidic conditions. The transparency of the dispersion is lower than that under neutral conditions. On the other hand, if the fibrous cellulose has high acid resistance, the decrease in viscosity and transparency of the dispersion liquid under acidic conditions is suppressed. In the present invention, even when the dispersion liquid of fibrous cellulose is set under 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 so that the solid content concentration became 0.2% by mass was set to H0, and the fibrous cellulose was set to hydrochloric acid. When the solid content concentration is 0.2% by mass and the pH is 4.2 ± 0.2 in ion-exchanged water, the haze is H1, the solid content concentration is 0.2% by mass, and the pH is 2.7 ± 0.2. When the haze 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. The value of H2-H0 is preferably 2.0 or less, more preferably 1.8 or less, and even more 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 is 0.2% by mass. A haze meter is used to measure the haze, and a glass cell for liquid having an optical path length of 1 cm is filled with a dispersion liquid. The zero point measurement is performed with ion-exchanged water contained in the glass cell.

Further, the viscosity (mPa · s) when the fibrous cellulose after the defibration treatment step was diluted with ion-exchanged water so that the solid content concentration became 0.2% by mass was set to ∨0, and the fibrous cellulose was changed to hydrochloric acid. When the solid content concentration is 0.2% by mass and the pH is 4.2 ± 0.2 in ion-exchanged water, the viscosity is V1, the solid content concentration is 0.2% by mass, and the pH is 2.7 ± 0.2. When the viscosity 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. 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 determined that the fibrous cellulose has excellent acid resistance. The viscosity of the aqueous dispersion at each pH was diluted so that the solid content concentration was 0.2% by mass, and then stirred with a disperser at 1500 rpm to make the slurry sufficiently uniform, and the relative humidity was 23 ° C. After standing in a 50% environment for 24 hours, the measurement is performed using a B-type viscometer. The measurement condition is 23 ° C., and the viscosity is measured for 30 seconds from the lapse of 2 minutes and 30 seconds to the end of rotation (after 3 minutes) when the rotation is performed 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 and may be 1000 nm or less. Further, 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, in the case of 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 the fibrous cellulose can be measured, for example, by observation with an electron microscope. The average fiber width of the fibrous cellulose may be larger than 1000 nm and may be 1000 nm or less. For example, when the average fiber width of the fibrous cellulose is larger than 1000 nm, it is preferably larger than 1 μm and 50 μm or less, more preferably larger than 1 μm and 40 μm or less, and further preferably larger than 1 μm and 30 μm or less. .. 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. It is particularly preferably 10 nm or less. The fibrous cellulose may be monofibrous cellulose, but the fibrous cellulose in the present specification also includes a fiber aggregate of monofibrous cellulose.

The average fiber width of 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 this suspension is cast on a hydrophilized carbon film-coated grid to be used as a sample for TEM observation. And. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Next, observation is performed using an electron microscope image at a magnification of 1000 times, 5000 times, 10000 times, or 50,000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification should be adjusted so as to satisfy the following conditions.
(1) A straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The width of the fiber intersecting the straight line X and the straight line Y is visually read with respect to the observation image satisfying the above conditions. In this way, at least three sets of observation images of surface portions that do not overlap each other are obtained. Next, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. As a result, at least 20 fibers × 2 × 3 = 120 fibers are read. Then, the average value of the read fiber widths is taken as the average fiber width of the fibrous cellulose.

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

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

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

The fibrous cellulose in the present embodiment has, for example, both a crystalline region and a non-crystalline region. In particular, fibrous cellulose having both a crystalline region and a non-crystalline region and having a high axial ratio is realized by the method for producing fibrous cellulose described later.

The fibrous cellulose of the present invention has a phosphoric acid group and a phosphite group. The amount of the phosphorous acid group (including the phosphorous acid group and the phosphorous acid group) introduced into the fibrous cellulose is preferably 0.10 mmol / g or more per 1 g (mass) of the fibrous cellulose, preferably 0.20 mmol / g. The above is more preferable, 0.50 mmol / g or more is further preferable, and 1.00 mmol / g or more is particularly preferable. Further, the amount of the phosphorus oxo acid group introduced into the fibrous cellulose is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of the fibrous cellulose, for example. It is more preferably 00 mmol / g or less. Here, the unit mmol / g indicates the amount of substituents per 1 g of mass of fibrous cellulose when the counterion of the phosphorus oxo acid group is a hydrogen ion (H ⁺ ). The amount of the substituent is the total amount of phosphoroxoic acid groups including a phosphoric acid group and a phosphite group. By setting the amount of the phosphorus oxo acid group introduced within the above range, the pH buffering capacity in the neutral region can be more effectively enhanced in the dispersion liquid containing the fibrous cellulose having a phosphorous acid group. Further, by setting the amount of the phosphorus oxo acid group introduced within the above range, the dispersibility of the fibrous cellulose in the solvent can be more effectively enhanced.

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

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

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

When the first dissociative acid amount (mmol / g) in the fibrous cellulose is A1 and the total dissociative 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 further preferable. Further, 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 amount of the first dissociating acid (A1) in the fibrous cellulose is the amount of alkali (mmol) required from the start of the titration to the first end point in the above-mentioned titration curve, and the solid content (g) in the slurry to be titrated. ) Divided by. That is, the first dissociated acid amount (A1) is a value obtained by dividing the amount of substance (mmol) of the acid that is ionized and neutralized in the first step by the solid content (g) in the slurry to be titrated. The total amount of dissociated acid (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 at all stages by the solid content (g) in the slurry to be titrated. Therefore, the closer the value of A1 / A2 is to 1, the smaller the amount of weak acid (such as the amount of weakly acidic group in the phosphorus oxo acid group). Further, the larger the difference between A2 and A1, the larger the amount of phosphoric acid group introduced into the phosphite group. In the embodiment of the present invention, by setting A1 and A2 to values satisfying the above conditions, the amount of phosphoric acid group and phosphite group introduced can be set to a preferable ratio, and the pH buffer of the fibrous cellulose-containing dispersion liquid can be set. The ability can be enhanced more effectively.

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

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

The phosphoric acid group and the phosphorous acid group may be present in the same cellulose molecular chain (cellulose single fiber). For example, a phosphate group may be introduced into one glucose and a phosphite group may be introduced into the other glucose among the two glucose units which are the basic structures constituting cellulose. Further, the fibrous cellulose of the present invention may be a fiber aggregate of a cellulose molecular chain having a phosphorous 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 phosphate group and a phosphite group (cellulose monofiber), a cellulose molecular chain having a phosphate group (cellulose monofiber), and phosphite. It may be a fiber aggregate of three kinds 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 phosphite 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 (where a = b × m). Of α and α', a are O ⁻ and the rest are OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, or an unsaturated-branched chain. A hydrocarbon group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. In addition, α in the formula (1) may be a group derived from a cellulose molecular chain.

In equation (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 chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , An unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. Above all, it is particularly preferable that α is a hydrogen atom. The α in the formula (2) does not include a group derived from the cellulose molecular chain.

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

Further, as the inducing group in α of the formula (2) or R of the formula (1), a functional group such as a carboxy group, a hydroxy group, or an amino group is used with respect to the main chain or side chain of the various hydrocarbon groups. Of these, functional groups in which at least one type is added or substituted can be mentioned, but the functional group is not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorus oxo acid group can be set to an appropriate range, and the permeability to the fiber raw material can be enhanced.

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 higher cations composed of organic substances include aliphatic ammonium or aromatic ammonium, and examples of monovalent or higher valent cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, and lithium. Examples thereof include cations of divalent metals such as calcium and magnesium, hydrogen ions, and the like, but the present invention is not particularly limited. These may be applied alone or in combination of two or more. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing β is heated and is easily industrially used, but is not particularly limited.

Further, the fibrous cellulose of the present invention may have a condensed phosphoroxoic acid group, and examples of the condensed phosphoric 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 (where a = b × m). Of α ¹ , α ² , ..., α ⁿ and α', a are O ⁻ , and the rest are either R or OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, or an unsaturated-branched chain. A hydrocarbon group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. In addition, α in the formula (3) may be a group derived from a cellulose molecular chain.

The specific example of each group in the formula (3) is the same as the specific example of each group in the formula (1), and the specific example of β ^{b +} in the formula (3) is β in the formula (1). It is the same as the specific example of ^{b +} .

Among the phosphorus oxo acid groups contained in the fibrous cellulose, the molar ratio of the substituent represented by the above formula (1) to the substituent represented by the above formula (2) (formula (1): formula (2)) is , 0.01: 99.99 to 99.99: 0.01, more preferably 1:99 to 99: 1, and even 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) among the phosphorous acid groups contained in the fibrous cellulose is 0.01: 99.99 to 99.99: 0. It is preferably 01, more preferably 1:99 to 99: 1, and even more preferably 10:90 to 90:10. By setting the molar ratio of the phosphoric acid group to the phosphorous acid group within the above range, the pH buffering property in the neutral region can be more effectively enhanced in the fibrous cellulose-containing dispersion having a phosphorous acid group. it can.

The fact that fibrous cellulose has a phosphite group as a substituent means that the infrared absorption spectrum of the dispersion containing fibrous cellulose is measured, and phosphones, which are tautomers of phosphorous acid groups, are measured around 1210 cm- ^1. It can be confirmed by observing the absorption of the acid group based on P = O. In addition, the fact that the fibrous cellulose has a phosphoric acid group as a substituent means that the infrared absorption spectrum of the dispersion containing the fibrous cellulose is measured, and the absorption of the phosphoric acid group based on P = O is performed in the vicinity of 1230 cm ^-1. It can be confirmed by observing. Further, the fact that fibrous cellulose has a phosphite group or a phosphate group as a substituent can be confirmed by a method of confirming a chemical shift by using NMR or a method of combining titration with elemental analysis.

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

(Manufacturing method of fibrous cellulose)
In the method for producing fibrous cellulose, 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 a urea and / or a urea derivative are mixed with a cellulose raw material. , Including the step of obtaining a cellulose raw material having a phosphoric acid group and a phosphorous acid group. In the following, the step of obtaining a cellulose raw material having a phosphoric acid group and a phosphorous acid group is also referred to as a phosphorous acid group introduction step.

<Cellulose raw material>
Fibrous cellulose is produced 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. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, and is, for example, broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), and unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton pulp such as cotton linter and cotton lint, and non-wood pulp such as hemp, straw and bagasse. The deinking pulp is not particularly limited, and examples thereof include deinking pulp made from used paper. As the pulp of the present embodiment, one of the above types may be used alone, or two or more types may be mixed and used. Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of availability. Further, among wood pulps, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable, from the viewpoint of obtaining long-fiber fibrous cellulose having a small decomposition of cellulose in the pulp and a large axial ratio.

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

<Linoxo acid group introduction process>
In the phosphorous 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. This is a step of obtaining a cellulose raw material having a phosphoric acid group and a phosphorous acid group. In the phosphorous acid group introduction step, phosphoric acid is formed by reacting a hydroxyl group of a fiber raw material containing cellulose with 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. A phosphorus oxo acid group containing a group and a phosphite group can be introduced. By this step, a cellulose raw material into which a phosphoric acid group and a phosphorous acid group have been introduced can be obtained. In the present specification, a compound having a phosphoric acid group and / or a salt thereof, and a compound group containing a compound having a phosphorous acid group and / or a salt thereof may be referred to as compound A, and urea and / or a compound thereof. Alternatively, the urea derivative may be referred to as compound B.

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

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 as the phosphoric acid, those having various puritys can be used, for example, 100% phosphoric acid (normal phosphoric acid) or 85% phosphoric acid is used. can do. Further, anhydrous phosphoric acid (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, and these can have various neutralization degrees. As the phosphoric acid, dehydration-condensed phosphoric acid (for example, pyrophosphoric acid, polyphosphoric acid, etc.) in which two or more molecules of phosphoric acid are condensed by a dehydration reaction may be used. Examples of the compound having a phosphorous acid group include phosphorous acid, and examples of phosphorous acid include 99% phosphorous acid (phosphonic acid). Examples of the salt of the compound having a phosphorous acid group include a lithium salt, a sodium salt, a potassium salt, and an ammonium salt of phosphorous acid, and these can have various neutralization degrees. Of these, phosphoric acid and phosphorous acid are highly efficient in introducing phosphoric acid groups, are more likely to improve defibration efficiency in the defibration step described later, are low in cost, and are easy to apply industrially. , Sodium salt of phosphoric acid or phosphorous acid, potassium salt of phosphoric acid or phosphorous acid, or ammonium salt of phosphoric acid or phosphorous acid is preferably used.

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

In the step of obtaining a cellulose raw material into which a phosphoric acid group and a phosphorous acid group have been introduced, a molar of 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 to be mixed as compound A. 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. It is more preferably: 10. By setting the ratio of each compound to be mixed as 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 having a phosphorous acid group.

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

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

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

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

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

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

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

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

<Washing process>
In the method for producing fibrous cellulose in the present embodiment, a washing step can be performed on the linoxoic acid group-introduced fiber as needed. The washing step is performed, for example, by washing the phosphorus oxo acid group-introduced fibers with water or an organic solvent. Further, the cleaning step may be performed after each step described later, and the number of cleanings performed in each cleaning step is not particularly limited.

<Alkaline treatment process>
In the case of producing fibrous cellulose, the phosphoric acid group-introduced fiber may be subjected to an alkali treatment between the phosphorus oxo acid group-introducing step and the defibration treatment step described later. The method of alkali treatment is not particularly limited, and examples thereof include a method of immersing a phosphorus oxo acid group-introduced fiber in an alkaline solution.

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

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time of the phosphorus oxo acid group-introduced fiber in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute 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 alkaline treatment step, the phosphoric acid group-introduced fiber may be washed with water or an organic solvent after the phosphoric acid group introduction step and before the alkaline 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 fibers with water or an organic solvent from the viewpoint of improving handleability.

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

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1,000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the phosphorus oxo acid group-introduced fiber. Is more preferable.

<Defibering 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 (phosphorous acid group-introduced fiber) is subjected to a micronization treatment, the fiber width is 1000 nm or less, and the phosphoric acid group and the phosphorous acid group are formed. This is a step of obtaining the fibrous cellulose to have. In the defibration treatment step, for example, a defibration treatment apparatus can be used. The defibrating apparatus is not particularly limited, but for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, and a twin shaft. A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, or a beater can be used. Among the above-mentioned defibration processing devices, it is more preferable to use a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by crushed media and less likely to cause contamination.

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

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

Examples of the solvent that the fibrous cellulose-containing substance may contain include water. Moreover, 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 the ketones include acetone, methyl ethyl ketone and the like. 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-like, 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 above-mentioned defibration treatment step may be a fibrous cellulose-containing substance. A fine fibrous cellulose-containing slurry may be obtained by concentrating or drying the fine fibrous cellulose-containing slurry and then redispersing it in a solvent. In this case, the redispersed 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, and examples thereof include water, an organic solvent, and a mixture of water and an organic solvent. Examples of the organic solvent include the above-mentioned solvents.

The content of fibrous cellulose with respect to 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, and 30% by mass. It is more preferably mass% or less, and particularly preferably 10 mass% or less. 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 being diluted 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 a glass cell for liquid having an optical path length of 1 cm is filled with a dispersion liquid. 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 even 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 viscosity is determined by diluting the fine fibrous cellulose-containing slurry so that the solid content concentration becomes 0.2% by mass, and then stirring the slurry at 1500 rpm with a disperser to make the slurry sufficiently uniform and relative to 23 ° C. It is a value measured using a B-type viscometer after being allowed to stand in an environment of 50% humidity for 24 hours. The measurement condition is 23 ° C., and the average value of the viscosity from the lapse of 2 minutes and 30 seconds to the end of the rotation when rotated at 3 rpm for 3 minutes is measured. As the measuring device, a digital viscometer DV-2T manufactured by BLOOKFIELD can be used.

<Arbitrary ingredient>
The fibrous cellulose-containing material may further contain an optional component. Examples of the optional component include antifoaming agents, lubricants, ultraviolet absorbers, dyes, pigments, stabilizers, surfactants, preservatives and the like. Further, the fibrous cellulose-containing slurry may contain a hydrophilic polymer, a hydrophilic low molecule, an organic ion and the like as optional components.

The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (excluding the above-mentioned cellulose fibers), and examples of the oxygen-containing organic compound include polyethylene glycol, polyethylene oxide, casein, dextrin, starch, and modification. Distillate, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylates, acrylic acid alkyl ester copolymer, urethane-based copolymer, cellulose derivative (hydroxyethyl cellulose, carboxy) Ethyl cellulose, carboxymethyl cellulose, etc.) and the like.

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

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

(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 molded body means a solid body formed into a desired shape or a solid body formed into a sheet. Examples of the molded product include sheets (including paper), beads, filaments, and the like. Above all, the molded product is preferably a sheet, beads or filament. When the molded product is bead-shaped, the particle size of the beads is preferably 0.1 mm or more and 10 mm or less. When the molded product is in the form of a 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, for example, 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. The upper limit of the thickness of the sheet is not particularly limited, but may be, for example, 1000 μm. The thickness of the sheet can be measured, for example, with a stylus type thickness gauge (Millitron 1202D manufactured by Marl Inc.).

If the fiber width of the fibrous cellulose is larger than 1000 nm, the sheet may be paper. Moreover, the sheet may be a non-woven fabric. Such sheets and non-woven fabrics may be used as constituent members of various sanitary papers and absorbent articles.

When the fiber width of the fibrous cellulose is 1000 nm or less, the sheet can 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 even more preferably 1% or less. On the other hand, the lower limit of the haze of the sheet is not particularly limited and may be, for example, 0%. Here, the haze of the sheet is a value measured, for example, in accordance with JIS K 7136 and using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

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, for example, 100%. Here, the total light transmittance of the sheet is a value measured using, for example, JIS K 7361 and a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

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, for example, JIS P 8124.

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, for example. Here, the density of the sheet can be calculated by measuring the thickness and mass of the sheet after adjusting the humidity of a 50 mm square sheet for 24 hours under the conditions of 23 ° C. and 50% relative humidity.

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 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 contain any component that may be included in the fibrous cellulose-containing slurry. Further, the sheet may contain water or an organic solvent.

(Manufacturing method of fibrous cellulose-containing sheet)
When the molded product is a sheet, the method for producing the fibrous cellulose-containing sheet includes a coating step of coating the fibrous cellulose-containing slurry on the substrate or a papermaking step of making the slurry, as described later. Is preferable.

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

The material of the base material used in the coating process is not particularly limited, but a material having higher wettability to the fibrous cellulose-containing slurry (slurry) may suppress shrinkage of the sheet during drying, but drying It is preferable to select a sheet in 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 is not particularly limited. For example, resin films and plates such as polypropylene, acrylic, polyethylene terephthalate, vinyl chloride, polystyrene, polycarbonate, and polyvinylidene chloride, metal films and plates of aluminum, zinc, copper, and iron plates, and their surfaces are oxidized. , Stainless film or plate, brass film or plate, etc. can be used.

In the coating process, if the viscosity of the slurry is low and it develops on the base material, a dammed frame is fixed on the base material to obtain a sheet with a predetermined thickness and basis weight. You may. The frame for damming is not particularly limited, but it is preferable to select, for example, a frame in which the end portion of the sheet that adheres after drying can be easily peeled off. From this point of view, a resin plate or a metal plate molded is more preferable. In the present embodiment, for example, a resin plate such as 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 a metal plate such as an aluminum plate, a zinc plate, a copper plate, or an iron plate. , And those whose surfaces are oxidized, stainless steel plates, brass plates and the like can be used. The coating machine for coating the slurry on the base material is not particularly limited, and 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 atmospheric temperature at the time of coating the slurry on the substrate are not particularly limited, but are preferably, for example, 5 ° C. or higher and 80 ° C. or lower, more preferably 10 ° C. or higher and 60 ° C. or lower, and 15 ° C. It is more preferably 50 ° C. or lower, and particularly preferably 20 ° C. or higher and 40 ° C. or lower. When the coating temperature is equal to or higher than the above lower limit, the slurry can be coated more easily. When the coating temperature is not more than the above upper limit value, volatilization of the dispersion medium during coating can be suppressed.

In the coating process, the slurry is based so that the finished basis weight of the sheet is preferably 10 g / m ² or more and 200 g / m ² or less, and 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.

As described above, the coating step includes a step of drying the slurry coated on the substrate. 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, and for example, a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method), or a method of vacuum drying (vacuum drying method) is applied. can do. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Drying with infrared rays, far infrared rays, or near infrared rays is not particularly limited, and can be performed using, for example, an infrared device, a far infrared device, or a near infrared device.

The heating temperature in the heat-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 set to the above lower limit value or more, the dispersion medium can be rapidly volatilized. Further, when the heating temperature is not more than the above upper limit value, it is possible to suppress the cost required for heating and suppress the discoloration of the fibrous cellulose due to heat.

<Papermaking process>
The papermaking process is performed by making a slurry with a paper machine. The paper machine used in the paper making process is not particularly limited, and examples thereof include continuous paper machines such as a long net type, a circular net type, and an inclined type, and a multi-layer paper making machine combining these. In the papermaking process, a known papermaking method such as hand-making may be adopted.

The papermaking process is performed by filtering and dehydrating the slurry with a wire to obtain a wet paper sheet, and then pressing and drying the 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. Such a filter cloth is not particularly limited, but for example, a sheet made of an organic polymer, a woven fabric, or a porous membrane is 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 porous membrane of polytetrafluoroethylene having a pore size of 0.1 μm or more and 20 μm or less, polyethylene terephthalate having a pore size of 0.1 μm or more and 20 μm or less, a polyethylene woven fabric, or the like can be mentioned.

In the sheeting process, a method of producing a sheet from a slurry is, for example, a water-squeezed section in which a slurry containing fibrous cellulose is discharged onto the upper surface of an endless belt and a dispersion medium is squeezed from the discharged slurry to generate a web. This can be done using a manufacturing apparatus comprising a drying section that dries the web to produce a sheet. An endless belt is arranged from the watering section to the drying section, and the web generated in the watering 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 a dehydration method usually used in the production of paper. Among these, a method of dehydrating with a long net, a circular net, an inclined wire or the like and then further dehydrating with a roll press is preferable. The drying method used in the papermaking process is not particularly limited, and examples thereof include methods 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 can be obtained, or a sheet in which fibrous cellulose is uniformly dispersed can be formed from the slurry. Further, the fibrous cellulose of the present invention can also be preferably used for mixing with an organic solvent containing a resin component. By mixing the fibrous cellulose of the present invention with 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 redispersed slurry can be used to form a film and used as various films.

Further, the fibrous cellulose of the present invention can be used, for example, as a reinforcing agent or an additive in cement, paints, inks, lubricants and the like. In addition, the molded body obtained by coating fibrous cellulose on a base material is a reinforcing material, an interior material, an exterior material, a packaging material, an electronic material, an optical material, an acoustic material, a process material, and a member of a transportation device. It is also suitable for applications such as electronic device members and electrochemical element members.

The features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, proportions, treatment contents, treatment procedures, etc. 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 construed as limiting by the specific examples shown below.

<Manufacturing example 1>
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 245 g / m ² sheets, dissociated and measured according to JIS P 8121, Canadian standard drainage degree (CSF) is 700 ml) It was used.

The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of phosphoric acid, phosphorous acid (phosphonic acid) and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to add 28.5 parts by mass of phosphoric acid and phosphorous acid (phosphonic acid). The contents were adjusted to 7.9 parts by mass, 120 parts by mass of urea, and 150 parts by mass of water to obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 250 seconds to introduce a phosphorus oxo acid group into the cellulose in the pulp to obtain a phosphorus oxo oxidized pulp.

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

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

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

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

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

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

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

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

<Measurement of infrared absorption spectrum>
The infrared absorption spectrum of the phosphorus oxo oxidized pulp (neutralized) and fine fibrous cellulose obtained in Production Examples 1 to 6 was measured using FT-IR. As a result, in the phosphorus oxo-oxidized pulp (neutralized) and fine fibrous cellulose obtained in Production Examples 1 to 3 and Production Examples 5, absorption based on P = O of the phosphoric acid group was observed around 1230 cm ^-1. It was confirmed that a phosphate 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 in the vicinity of 1210 cm ^-1 , and the phosphite group (phosphorous acid group) was observed in cellulose. It was confirmed that a phosphonic acid group) was added.

<X-ray diffraction analysis>
When the phosphorus oxo oxide pulp (neutralized) obtained in Production Examples 1 to 6 was tested and analyzed by an X-ray diffractometer, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23. Typical peaks were confirmed at two positions near ° or less, and it was confirmed that they had cellulose type I crystals. Further, it was 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 using a transmission electron microscope and found to be 3 to 5 nm.

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

<Example 2>
With respect to the fibrous cellulose-containing slurry obtained in Production Example 2, the amount of the first dissociated acid introduced into the cellulose, the total amount of the dissociated acid, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. Further, 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 method described later. Further, 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 was obtained. The haze and viscosity of these slurries were also measured by the methods described below.

<Example 3>
With respect to the fibrous cellulose-containing slurry obtained in Production Example 3, the amount of the first dissociated acid introduced into the cellulose, the total amount of the dissociated acid, 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>
With respect to the fibrous cellulose-containing slurry obtained in Production Example 4, the amount of the first dissociated acid introduced into the cellulose, the total amount of the dissociated acid, 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 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 are mixed so that the mass of the fibrous cellulose is 1: 1 and contains the fibrous cellulose of Example 5. It was made into a slurry. For this fibrous cellulose-containing slurry, the amount of the first dissociated acid introduced into the cellulose, the total amount of the dissociated acid, and the pH buffering capacity in the neutral region were measured in the same manner as in Example 1. In addition, the haze and viscosity of the fibrous cellulose-containing slurry of Example 5 were measured in the same manner as in Example 2.

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

<Example 7>
The haze and viscosity of the fibrous cellulose-containing slurry obtained in Production Example 5 were measured 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, an ion exchange resin is used for a fibrous cellulose-containing slurry prepared by diluting a microfilament-like cellulose dispersion containing fibrous cellulose with ion-exchanged water so that the content is 0.2% by mass. After the treatment, it was measured by titration with an alkali.
In the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, which has been conditioned) with a volume of 1/10 is added to the fibrous cellulose-containing slurry, and the slurry is shaken for 1 hour. , The resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm.
For titration using alkali, the change in pH value indicated by the slurry is measured while adding 10 μL of a 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry treated with an ion exchange resin every 5 seconds. I went by doing. The titration was carried out while blowing nitrogen gas into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 1). The amount of alkali required from the start of the titration to the first end point is equal to the amount of the first dissociated acid in the slurry used for the titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated was defined as the amount of first dissociating acid (mmol / g). Further, the 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 defined as the total amount of dissociated acid (mmol / g).

<Evaluation of pH buffering capacity in the neutral region>
After undergoing the treatment step with an ion exchange resin in <Measurement of first dissociation acid amount and total dissociation acid amount>, nitrogen gas is blown into a slurry containing fibrous cellulose in which a phosphorus oxo acid group is converted into an acid type for 15 minutes. , 0.1N sodium hydroxide solution was added to adjust the pH of the slurry to 6.5. Further, a 0.1 N 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.

<Haze measurement method for fibrous cellulose-containing slurry>
Haze is a measure of the transparency of a 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 Technology Research Institute) to measure the optical path length of 1 cm. Measurement was performed in accordance with JIS K 7136 using a liquid glass cell (manufactured by Fujiwara Seisakusho, MG-40, backlit path). The zero point measurement was performed with ion-exchanged water contained in the same glass cell.

<Method for measuring viscosity of fibrous cellulose-containing slurry>
The viscosity of the fibrous cellulose-containing slurry was diluted so that the solid content concentration of the fibrous cellulose-containing slurry was 0.2% by mass, and then stirred with a disperser at 1500 rpm to make the slurry sufficiently uniform. The obtained slurry was allowed to stand in an environment of 23 ° C. and a relative humidity of 50% 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 conditions were 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 the rotation was performed at 3 rpm for 3 minutes, and the average value was calculated. ..

In Examples 1 to 5, it was confirmed that the pH buffering ability in the neutral region was high. Further, in Examples 2 to 5, the values of H1-H0 and H2-H0 were smaller than those of 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. As described above, in Examples 1 to 5, it was confirmed that the acid resistance was also excellent.

Claims (5)

Fibrous cellulose containing a phosphoric acid group and a phosphorous acid group. When the amount of the first dissociating acid in the fibrous cellulose is A1 and the total amount of dissociating acid in the fibrous cellulose is A2, the values of A1 / A2 are 0.51 or more and 0.97 or less, and A2 and A1. 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. 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 a urea and / or a urea derivative are mixed with a cellulose raw material to form a phosphoric acid group and a phosphorous acid. A method for producing fibrous cellulose, which comprises a 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 and 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 fibrous cellulose is mixed so as to be 0.01.

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