JP2020158693A - Composition - Google Patents

Abstract

To provide a composition that has an excellent dispersion stability and pumping property, and furthermore, in which when the composition is used as a fluid dispersion, the viscosity of the fluid dispersion is low and the handling property during use is excellent.SOLUTION: A composition is used to mix with calcium carbonate powder to produce a concrete pump pressure sending leading agent, said composition containing at least one selected from the group consisting of a fine fibrous modified cellulose having an ionic group and having a fiber width of 1,000 nm or less, a pulp fiber having a fiber width of 10 μm or more, and a fine fibrous cellulose having a fiber width of 1,000 nm or less and having no ionic group.SELECTED DRAWING: None

Description

The present invention relates to a composition containing fine fibrous modified cellulose and mixed with calcium carbonate powder to produce a precursor for pumping concrete pumps.

In the foundation work of buildings and the construction work of concrete buildings, the work of driving concrete into a predetermined place is carried out.
In recent years, a method of transporting concrete supplied to a hopper to a predetermined casting place by using a concrete pump truck has been widely adopted. In this method, the concrete in the hopper is pumped into the pipe using a concrete pump truck, and the concrete is transported to the target casting place through the pipe. When concrete is pumped using a concrete pump and piping, the hopper is pre-filled with cement paste or mortar, which is a mixture of water and cement as a pumping precursor, as a pumping precursor, and is used for pumping. The precursor is first fed into the pipe, and then the ready-mixed concrete is continuously fed into the pipe and pumped while pouring the ready-mixed concrete into the hopper. In this way, when the pre-hardened ready-mixed concrete (fluid concrete) is introduced without any treatment, only the mortar component (cement paste) out of the constituents of the concrete is sent first. This is because the tip of the concrete that adheres to the surface inside the pump or the pipe and has lost the mortar content may gradually separate and block the pipe.

In the method of using cement paste or mortar as a precursor for pumping, the hardening reaction proceeds during transportation or waiting at the concrete driving destination, so it is necessary to make a detailed management plan for the concrete driving work. Further, in this method, it is necessary to set a large amount of the cement paste or mortar used as the pumping precursor in order to obtain the required effect, and further, the cement paste or mortar used as the pumping precursor is discarded. Not only is it not economical, but cement paste and mortar are likely to adversely affect the quality of concrete.

Patent Document 1 discloses a pressure-feeding initiator for a concrete pump containing a water-absorbent resin for the purpose of realizing a pressure-feeding initiator for a concrete pump that can smoothly start pumping of concrete with a small amount of use. There is.
Further, in Patent Document 2, cellulose nanofibers are added for the purpose of providing a pumping leading material capable of extending the pumping distance with a very small amount of input, and calcium carbonate is the main component. A preceding material for pumping, which is characterized in that, is disclosed.

Japanese Unexamined Patent Publication No. 2000-34461 Japanese Patent No. 6437679

The pumping precursor described in Patent Document 1 is inferior in economy, such as using a water-absorbent resin, and has problems such as insufficient water absorption of the water-absorbent resin depending on the conditions of use. .. Further, as the pumping precursor described in Patent Document 2, a pumping precursor having more excellent pumping property has been required.
An object of the present invention is to provide a composition which is excellent in dispersion stability and pumping property, and when the composition is used as a dispersion liquid, the viscosity of the dispersion liquid is low and the handleability at the time of use is excellent. ..

The present inventors have prepared fine fibrous modified celluloses substituted with ionic groups and having a fiber width of 1,000 nm or less, pulp fibers having a fiber width of 10 μm or more, and fiber widths of 1,000 nm or less. It has been found that the above problems can be solved by adopting a composition containing at least one selected from fine fibrous cellulose having no ionic group.
That is, the present invention relates to the following <1> to <8>.
<1> A composition used for producing a precursor for pumping concrete pumps by mixing with calcium carbonate powder, wherein the composition has an ionic group and has a fiber width of 1,000 nm or less. Includes certain fine fibrous modified celluloses, pulp fibers having a fiber width of 10 μm or more, and at least one selected from the group consisting of fine fibrous celluloses having a fiber width of 1,000 nm or less and having no ionic group. ,Composition.
<2> The composition according to <1>, wherein the viscosity of the composition (solid content concentration 0.4% dispersion, 23 ° C.) is 100 mPa · s or more and 3000 mPa · s or less.
<3> The composition contains pulp fibers having a fiber width of 10 μm or more, and the mass ratio of the pulp fibers to the fine fibrous modified cellulose (pulp fiber / fine fibrous modified cellulose) is 30/70 or more. The composition according to <1> or <2>, which is 90/10 or less.
<4> The mass ratio of the fine fibrous cellulose containing the fine fibrous cellulose having no ionic group to the fine fibrous modified cellulose (containing the ionic group). The composition according to <1> or <2>, wherein the amount of fine fibrous cellulose / fine fibrous modified cellulose) is 30/70 or more and 90/10 or less.
<5> The composition according to any one of <1> to <4>, wherein the content of the calcium carbonate powder in the solid content of the concrete pump pumping precursor is 50% by mass or more.
<6> The composition according to any one of <1> to <5>, wherein the mixing amount of the composition with respect to 100 parts by mass of the calcium carbonate powder is 0.0001 part by mass or more and 0.1 part by mass or less.
<7> The composition according to any one of <1> to <6>, wherein the calcium carbonate powder contains a porous calcium carbonate powder.
<8> The composition according to any one of <1> to <7>, which is further mixed with at least one selected from a pigment, an antioxidant, and a pH adjuster.

According to the present invention, it is possible to provide a composition which is excellent in dispersion stability and pumping property, and when the composition is used as a dispersion liquid, the viscosity of the dispersion liquid is low and the handleability at the time of use is excellent. ..

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. FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to the fibrous cellulose-containing slurry having a carboxy group and the pH.

[Composition]
The composition of the present invention is a composition used for producing a precursor for pumping concrete pump by mixing with calcium carbonate powder, and the composition has an ionic group and has a fiber width. Selected from the group consisting of fine fibrous modified cellulose having a fiber width of 1,000 nm or less, pulp fibers having a fiber width of 10 μm or more, and fine fibrous cellulose having a fiber width of 1,000 nm or less and having no ionic group. Includes at least one.
Here, "fine fibrous modified cellulose having an ionic group and a fiber width of 1,000 nm or less" is also simply referred to as "fine fibrous modified cellulose" or "modified CNF".
Further, "pulp fiber having a fiber width of 10 μm or more" is also simply referred to as "pulp fiber". Further, "fine fibrous cellulose having a fiber width of 1,000 nm or less and having no ionic group" is also referred to as "fine fibrous unmodified cellulose" or "unmodified CNF".
Further, the fine fibrous modified cellulose and the fine fibrous unmodified cellulose are collectively referred to as "fine fibrous cellulose".
That is, the composition of the present invention contains at least one selected from the group consisting of fine fibrous modified cellulose (modified CNF) and pulp fibers and fine fibrous unmodified cellulose (unmodified CNF).

By adding the composition of the present invention to a predecessor for pumping containing calcium carbonate, a predecessor for pumping a concrete pump having excellent dispersion stability and pumping property (hereinafter, "preceding agent for pumping" or "preceding agent"" Also called) is obtained. Further, the dispersion liquid of the composition of the present invention has a low viscosity and is excellent in handleability in actual use.
The detailed reason why the above effect is obtained is unclear, but some are presumed as follows.
The composition of the present invention contains fine fibrous modified cellulose and exhibits a high thickening effect and a high particle dispersion effect when added to water to form a slurry. On the other hand, the slurry has thixotropic properties and its viscosity decreases when it is subjected to shear stress.
The composition of the present invention is mixed with calcium carbonate powder to prepare a precursor for pumping concrete pumps, but when it is actually pumped into a pipe as a precursor, the precursor for pumping contains water. .. As a result, it is considered that the composition of the present invention imparts high dispersion stability to the calcium carbonate powder and can obtain excellent pumping property. In particular, it is considered that high dispersion stability with respect to calcium carbonate and excellent pumping property were obtained by containing fine fibrous modified cellulose (modified CNF) having an ionic group.
In actual use, the composition of the present invention should be added as a dispersion rather than as a solid or powder from the viewpoint of preparing a uniform pumping precursor and shortening the preparation time. Is preferable. The viscosity of the dispersion containing the modified CNF tends to be higher than the viscosity of the dispersion containing only pulp fibers or unmodified CNF. By containing, in addition to the modified CNF, at least one selected from the group consisting of pulp fibers and unmodified CNF, the composition of the present invention is surprisingly dispersed, although the reason is unknown. It has been found that the amount of modified CNF used can be reduced without impairing stability and pumpability. As a result, the viscosity of the dispersion can be reduced, and a composition having excellent handleability in actual use can be obtained.
Hereinafter, the present invention will be described in more detail.

<Fine fibrous modified cellulose>
The composition of the present invention contains fine fibrous modified cellulose (modified CNF), and the fine fibrous modified cellulose is a fibrous cellulose having a fiber width of 1,000 nm or less and has an ionic group. The fiber width of the fine fibrous modified cellulose can be measured by, for example, observation with an electron microscope.

The fiber width of the fine fibrous modified cellulose is preferably 100 nm or less, more preferably 30 nm or less, and further preferably 8 nm or less. The fiber width is preferably 2 nm or more.
The average fiber width of the fine fibrous modified cellulose is, for example, 1,000 nm or less. The average fiber width of the fine fibrous modified cellulose is, for example, preferably 2 nm or more, preferably 1,000 nm or less, more preferably 100 nm or less, still more preferably 50 nm or less, still more preferably 10 nm or less. By setting the average fiber width of the fine fibrous modified cellulose to 2 nm or more, it is possible to suppress the dissolution of the fine fibrous modified cellulose in water as a cellulose molecule, and the composition containing the fine fibrous modified cellulose has the effect of improving dispersion stability and pumping property. Can be more easily expressed. The fine fibrous modified cellulose is, for example, monofibrous cellulose.

The average fiber width of the fine fibrous modified cellulose is measured as follows, for example, using an electron microscope. First, an aqueous suspension of fine fibrous modified 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 for TEM observation. Use as a sample for use. 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 1,000 times, 5,000 times, 10,000 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 fine fibrous modified cellulose.

The fiber length of the fine fibrous modified cellulose is not particularly limited, but is preferably 0.1 μm or more and 1,000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and 0.1 μm or more and 600 μm or less. It is more preferable to have. By setting the fiber length within the above range, destruction of the crystal region of the fine fibrous modified cellulose can be suppressed. In addition, the slurry viscosity of the fine fibrous modified cellulose can be set in an appropriate range. The fiber length of the fine fibrous cellulose can be obtained by, for example, image analysis by TEM, SEM, or AFM.

The fine fibrous modified cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous modified cellulose has an I-type crystal structure can be identified in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatic with graphite. Specifically, it can be identified by having typical peaks at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less.
The ratio of the type I crystal structure to the fine fibrous modified 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 dispersion stability and pumping property. 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 fine fibrous modified cellulose is not particularly limited, but is preferably 20 or more and 10,000 or less, and more preferably 50 or more and 1,000 or less. By setting the axial ratio to the above lower limit value or more, high dispersion stability of the calcium carbonate powder can be easily obtained. By setting the axial ratio to the above upper limit value or less, for example, when treating fine fibrous cellulose as an aqueous dispersion, it is preferable in that handling such as dilution becomes easy.

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

The fine fibrous modified cellulose in this embodiment has an ionic group. When the fine fibrous modified cellulose has an ionic group, the dispersibility of the fibers in the dispersion medium (water) can be improved, and the defibration efficiency in the defibration treatment can be improved. Further, when a preceding agent for pumping concrete pump is produced by mixing with calcium carbonate powder, the dispersibility of calcium carbonate in water is improved and the pumping property is improved.
The ionic group can include, for example, either one or both of an anionic group and a cationic group. In the present embodiment, it is particularly preferable to have an anionic group as the ionic group.
Further, the fine fibrous modified cellulose may have a nonionic group introduced in addition to the ionic group, and examples of the nonionic group include an alkyl group and an acyl group.

Examples of the anionic group as an ionic group include a phosphorus oxo acid group or a group derived from a phosphorus oxo acid group (sometimes simply called a phosphorus oxo acid group), a carboxy group or a group derived from a carboxy group (also simply called a carboxy group). There is), and at least one selected from a sulfone group or a group derived from a sulfone group (sometimes simply referred to as a sulfone group), and at least one selected from a phosphoric acid group and a carboxy group. It is more preferable, and it is particularly preferable that it is a phosphorusoxo acid group.

The phosphorus oxo acid group or the group derived from the phosphorus oxo acid group is, for example, a group represented by the following formula (1), and is generalized as a phosphorus oxo acid group or a group derived from the phosphorus oxo acid.
The phosphorus oxo acid group is, for example, a divalent functional group obtained by removing a hydroxy group from a phosphorus oxo acid. Specifically, it is a group represented by −PO ₃ H ₂ . The group derived from the phosphorus oxo acid group includes a group such as a salt of the phosphorus oxo acid group and a phosphorus oxo acid ester group. The group derived from the phosphoric acid group may be contained in the fine fibrous modified cellulose as a group in which the phosphoric acid group is condensed (for example, a pyrophosphate group). Further, the phosphorous acid group may be, for example, a phosphorous acid group (phosphonic acid group), and the group derived from the phosphorous acid group may be a salt of a phosphorous acid group, a phosphorous acid ester group, or the like. Good.

In the formula (1), a, b and n are natural numbers, and m is an arbitrary number (where a = b × m). Of α ¹ , α ² , ..., α ⁿ and α', a are O ⁻ , and the rest are either R or OR. It is also possible that all of each α ⁿ and α'are O ⁻ . R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, and an unsaturated-branched chain hydrocarbon, respectively. A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. In addition, α in the formula (1) may be a group derived from a cellulose molecular chain.
Examples of the saturated-linear hydrocarbon group include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like. 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, but are not limited to, a vinyl group, an allyl group and the like. 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, but are not limited to, a phenyl group, a naphthyl group and the like.

Further, as the inducing group in R, a functional group in which at least one of functional groups such as a carboxy group, a hydroxy group, or an amino group is added or substituted with respect to the main chain or side chain of the above-mentioned various hydrocarbon groups. The group is mentioned, but it is not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorus oxo acid group can be set to an appropriate range, the penetration into the fiber raw material is facilitated, and the yield of the fine cellulose fiber is increased. You can also do it.

β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include 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.

The amount of the ionic group introduced in the modified CNF is, for example, 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g or more per 1 g (mass) of the modified CNF. It is more preferably 1.00 mmol / g or more, and even more preferably 1.00 mmol / g or more. The amount of the ionic group introduced in the modified CNF is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and 3.50 mmol / g per 1 g (mass) of the modified CNF. It is more preferably less than or equal to, and even more preferably 3.00 mmol / g or less. By setting the amount of the ionic group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous modified cellulose. Further, by setting the amount of the ionic group introduced within the above range, the composition containing the fine fibrous modified cellulose can exhibit good properties for improving the dispersion stability and the pumping property.
Here, the denominator in the unit mmol / g indicates the mass of the modified CNF when the counter ion of the ionic group is a hydrogen ion (H ⁺ ).

The amount of ionic groups introduced into the modified CNF can be measured, for example, by the neutralization titration method. In the measurement by the neutralization titration method, the introduction amount is measured by determining the change in pH while adding an alkali such as an aqueous sodium hydroxide solution to the obtained slurry containing the modified CNF.
FIG. 1 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of a modified CNF-containing slurry having a phosphorus oxo acid group. The amount of phosphorus oxo acid group introduced into the modified CNF is measured, for example, as follows. In the following description, the measuring method for the modified CNF will be described, but the same applies to the measurement for the ionic group-introduced fiber and the pulp fiber into which the ionic group is introduced when producing the modified CNF.
First, the slurry containing the modified CNF 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 dissociated acid of the modified CNF contained in the slurry used for titration, and the amount of alkali required from the first end point to the second end point. Is equal to the amount of second dissociated acid of the modified CNF contained in the slurry used for titration, and the amount of alkali required from the start of titration to the second end point is the total dissociation of the modified CNF contained in the slurry used for titration. Equal to the amount of 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 this phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently It decreases, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) is consistent with 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.

Since the denominator of the above-mentioned phosphorus oxo acid group introduction amount (mmol / g) indicates the mass of the acid type modified CNF, the phosphorus oxo acid group amount (hereinafter, acid) of the acid type modified CNF (hereinafter, acid). Type)) is shown. On the other hand, when the counterion of the phosphorus oxo acid group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of the modified CNF when the cation C is a counterion. Then, the amount of phosphorus oxo acid groups (hereinafter, the amount of phosphorus oxo acid groups (C type)) possessed by the modified CNF whose cation C is a counterion can be determined.
That is, it is calculated by the following formula.
Phosphoric acid group amount (C type) = Phosphoric acid group amount (acid type) / {1+ (W-1) x A / 1,000}
A [mmol / g]: Total anion amount derived from the phosphoric acid group of the modified CNF (total dissociated acid amount of the phosphoric acid group)
W: Formula unit of cation C per valence (for example, Na is 23, Al is 9)

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 modified CNF-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.

FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to the modified CNF having a carboxy group and the pH.
The amount of carboxy group introduced into the modified CNF is measured, for example, as follows.
First, the slurry containing the modified CNF 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 to obtain a titration curve as shown in FIG. If necessary, the same defibration treatment as the defibration treatment step described later may be performed on the measurement target.
As shown in FIG. 2, in this neutralization titration, there is one point in which the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Observed. The maximum point of this increment is called the first end point. Here, the region from the start of titration to the first end point in FIG. 2 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the slurry used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the modified CNF-containing slurry to be titrated to reduce the amount of carboxy group introduced (mmol / g). calculate.
The above-mentioned amount of carboxy group introduced (mmol / g) is the amount of substituents per 1 g of mass of the modified CNF when the counterion of the carboxy group is hydrogen ion (H ⁺ ) (hereinafter, the amount of carboxy group (acid type). ) Is shown.
Since the denominator of the above-mentioned carboxy group introduction amount (mmol / g) is the mass of the acid type modified CNF, the carboxy group amount of the acid type modified CNF (hereinafter referred to as the carboxy group amount (acid type)) Call). On the other hand, when the counterion of the carboxy group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of the modified CNF when the cation C is a counterion. , The amount of carboxy group (hereinafter, carboxy group amount (C type)) (mmol / g) possessed by the modified CNF in which the cation C is a counter ion can be determined.
That is, it is calculated by the following formula.
Amount of carboxy group (C type) = Amount of carboxy group (acid type) / {1+ (W-1) x (amount of carboxy group (acid type)) / 1,000}
W: Formula unit of cation C per valence (for example, Na is 23, Al is 9)

In the measurement of the amount of substituents by the titration method, if the titration interval of the aqueous sodium hydroxide solution is too short, the amount of substituents may be lower than the original amount. Therefore, an appropriate titration interval, for example, 0.1 N hydroxide. It is desirable to titrate 10 to 50 μL of the aqueous sodium solution every 5 to 30 seconds.

<Fine fibrous undenatured cellulose>
The composition of the present invention contains at least one selected from pulp fibers and unmodified CNF, in addition to the modified CNF described above.
The preferable ranges of the fiber width, average fiber width, fiber length, crystal structure, and axial ratio of the unmodified CNF are the same as the preferable ranges of the fiber width, average fiber width, fiber length, crystal structure, and axial ratio of the modified CNF. ..

<Manufacturing method of fine fibrous modified cellulose and fine fibrous unmodified cellulose>
(Fiber raw material containing cellulose)
Modified CNFs and unmodified CNFs are made from fiber raw materials containing cellulose.
The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, but 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, from the viewpoint of high cellulose ratio and high yield of fine fibrous cellulose during defibration treatment, long fiber fine fibrous cellulose having a small decomposition of cellulose in pulp and a large axial ratio can be obtained. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable. When long-fiber fine fibrous cellulose having a large axial ratio is used, the viscosity of the slurry containing the fine fibrous cellulose tends to increase.
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.

In order to obtain the above-mentioned fine fibrous modified cellulose into which an ionic group has been introduced, an ionic group introduction step, a washing step, and an alkali treatment step (neutralization) in which the ionic group is introduced into the above-mentioned fiber raw material containing cellulose Step), it is preferable to have a defibration treatment step in this order, and an acid treatment step may be provided instead of the washing step or in addition to the washing step. Examples of the ionic group introduction step include a phosphorus oxo acid group introduction step and a carboxy group introduction step.
Further, in order to obtain fine fibrous cellulose having no ionic group, the above-mentioned fiber raw material containing cellulose may be defibrated.
Each will be described below.

(Ionic group introduction process)
[Linoxo acid group introduction step]
In the phosphorus oxo acid group introduction step, at least one compound (hereinafter, also referred to as “compound A”) selected from compounds capable of introducing a phosphorus oxo acid group by reacting with a hydroxyl group of a fiber raw material containing cellulose is used to introduce cellulose. This is a process of acting on the fiber raw material contained therein. By this step, a phosphorus oxo acid group-introduced fiber can be obtained.

In the phosphorus oxo acid group introduction step according to the present embodiment, the reaction between the fiber raw material containing cellulose and Compound A is carried out in the presence of at least one selected from urea and its derivatives (hereinafter, also referred to as “Compound B”). You may. On the other hand, the reaction of the fiber raw material containing cellulose with the compound A may be carried out in the absence of the compound B.
As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B, there is a method of mixing the compound A and the compound B with the fiber raw material in a dry state, a wet state or a slurry state. Of these, since the reaction uniformity is high, it is preferable to use a fiber raw material in a dry state or a wet state, and it is particularly preferable to use a fiber raw material in a dry state. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. Examples of the compound A and the compound B include a method of adding the compound A and the compound B to the fiber raw material in the form of a powder or a solution dissolved in a solvent, or in a state of being heated to a melting point or higher and melted. Of these, since the reaction 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.

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

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

Compound B used in this embodiment is at least one selected from urea and its derivatives as described above. Examples of compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.
From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. Further, from the viewpoint of further improving the uniformity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.
The amount of compound B added to the fiber raw material (absolute dry mass) is not particularly limited, but is preferably 1% by mass or more and 500% by mass or less, and more preferably 10% by mass or more and 400% by mass or less. It is more preferably 100% by mass or more and 350% by mass or less.

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

In the phosphorus oxo acid group introduction step, it is preferable to add or mix 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 thin sheet-shaped fiber raw material is impregnated with compound A or the like and then heated, or the fiber raw material and compound A or the like are kneaded or stirred with a kneader or the like. While heating can be adopted. This makes it possible to suppress uneven concentration of the compound A or the like 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 or the like 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). It is considered that this is due to the fact that it is possible to suppress the occurrence of.
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. 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 fine fibrous cellulose having a high axial ratio.

The heat treatment time is preferably 1 second or more and 300 minutes or less, more preferably 1 second or more and 1,000 seconds or less, and 10 seconds or more and 800, for example, after the water is substantially removed from the fiber raw material. More preferably, it is less than a second. 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 phosphoric acid group introduction step two or more times, many phosphoric 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.

The amount of the phosphorus oxo acid group with respect to the fiber raw material is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g or more per 1 g (mass) of the fibrous cellulose, for example. Is more preferable, and 1.00 mmol / g or more is particularly preferable. The amount of the phosphorus oxo acid group introduced into the fiber raw material is, for example, preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and 3.00 mmol per 1 g (mass) of fibrous cellulose. It is more preferably less than / g. By setting the amount of the phosphorus oxo acid group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous modified cellulose.

[Carboxy group introduction step]
The carboxy group introduction step has an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a group derived from carboxylic acid or a derivative thereof, or a group derived from carboxylic acid with respect to the fiber raw material containing cellulose. This is done by treating with an acid anhydride of the compound or a derivative thereof.

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

When the TEMPO oxidation treatment is carried out in the carboxy group introduction step, it is preferable to carry out the treatment under conditions of pH 6 or more and 8 or less, for example. Such a treatment is also referred to as a neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) as a catalyst, and the like. This can be done by adding a nitroxy radical and sodium hypochlorite as a sacrificial reagent. Further, by coexisting sodium chlorite, the aldehyde generated in the oxidation process can be efficiently oxidized to the carboxy group.
Further, the TEMPO oxidation treatment may be carried out under the condition that the pH is 10 or more and 11 or less. Such a treatment is also referred to as an alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be carried out, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a co-catalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. ..

The amount of carboxy group introduced into the fiber raw material varies depending on the type of substituent, but for example, when a carboxy group is introduced by TEMPO oxidation, it is preferably 0.10 mmol / g or more per 1 g (mass) of fibrous cellulose. It is more preferably 0.20 mmol / g or more, further preferably 0.50 mmol / g or more, and particularly preferably 0.90 mmol / g or more. Further, it is preferably 2.5 mmol / g or less, more preferably 2.20 mmol / g or less, and further preferably 2.00 mmol / g or less. In addition, when the substituent is a carboxymethyl group, it may be 5.8 mmol / g or less per 1 g (mass) of fibrous cellulose.

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

(Alkaline treatment process)
When producing the fine fibrous modified cellulose, the ionic group-introduced fiber may be subjected to an alkali treatment between the ionic group-introducing step and the defibration treatment step described later. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the ionic 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 ionic 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 1,000% by mass or more, with respect to the absolute dry mass of the ionic group-introduced fiber, for example. More preferably, it is 10,000% by mass or less.

In order to reduce the amount of the alkaline solution used in the alkaline treatment step, the ionic group-introduced fibers may be washed with water or an organic solvent after the ionic 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 ionic group-introduced fibers with water or an organic solvent from the viewpoint of improving handleability.

(Acid treatment process)
In the case of producing fine fibrous modified cellulose, the ionic group-introduced fiber may be subjected to acid treatment between the step of introducing the ionic group and the defibration treatment step described later. For example, the ionic group introduction step, the acid treatment, the alkali treatment and the defibration treatment may be performed in this order.
The acid treatment method is not particularly limited, and examples thereof include a method of immersing the ionic group-introduced fiber in an acidic solution containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably, for example, 10% by mass or less, and more preferably 5% by mass or less. The pH of the acidic 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, with respect to the absolute dry mass of the ionic group-introduced fiber. More preferably, it is 10,000% by mass or less.

(Defibering process)
Fine fibrous modified cellulose can be obtained by defibrating the ionic group-introduced fiber in the defibration treatment step. Further, by defibrating the fibers into which no ionic group has been introduced, fine fibrous unmodified cellulose can be obtained.
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 ionic group-introduced fiber or the ionic group-introduced fiber with a dispersion medium into 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, aproton 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, in the slurry obtained by dispersing the ionic group-introduced fiber or the ionic group-introduced fiber in a dispersion medium, an ionic group-introduced fiber such as urea having a hydrogen bond or an ionic group is contained in the slurry. It may contain solids other than unintroduced fibers.

In the present invention, commercially available products can also be used as the modified CNF and the unmodified CNF. Commercially available modified CNFs include Auro Visco (Oji Holdings Co., Ltd., phosphate group-introduced modified CNF), Leocrysta (Daiichi Kogyo Seiyaku Co., Ltd., carboxy group-introduced modified CNF), and Serempia (Nippon Paper Co., Ltd. BiNFi-s (manufactured by Sugino Machine Co., Ltd.) and the like are exemplified as commercially available products manufactured by carboxymethyl group-introduced modified CNF or carboxy group-introduced modified CNF) and unmodified CNF.

<Pulp fiber>
The composition of the present invention contains pulp fibers having a fiber width of 10 μm or more.
The pulp fiber has a fiber width of 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, still more preferably 50 μm or less.
When the fiber width of the pulp fiber is within the above range, the viscosity of the dispersion liquid of the composition can be lowered without impairing the dispersion stability of the calcium carbonate powder.
The pulp fiber includes a pulp fiber having a branch-like portion having a width of 1,000 nm or less on its surface.
The pulp fiber may or may not have an ionic group.
As the pulp fiber, the above-mentioned fiber raw material containing cellulose may be beaten and used.
The fiber width of the pulp fiber can be measured using a Kajaani fiber length measuring machine (Kajaani Automation Co., Ltd., FS-200 type).

The pulp fiber preferably has an ionic group, and as the ionic group, the ionic group exemplified in the modified CNF is similarly exemplified, and the preferable range is also the same. Pulp fibers having an ionic group can be produced by the same method as the modified CNF except that it does not have a defibration step.

<Physical properties of composition>
(Content ratio of modified CNF, unmodified CNF, and pulp fiber)
The composition of the present invention contains a modified CNF and at least one selected from the group consisting of pulp fibers and unmodified CNF.
The composition of the present invention may contain three modified CNFs, pulp fibers, and unmodified CNFs, but preferably contains modified CNFs and pulp fibers, or modified CNFs and unmodified CNFs. It is more preferable to contain modified CNF and pulp fiber from the viewpoint of obtaining a dispersion having a low viscosity.
When the composition of the present invention contains modified CNF and pulp fiber, that is, when it contains modified CNF and pulp fiber without containing unmodified CNF, the mass ratio of pulp fiber to modified CNF (pulp fiber / The modified CNF) is preferably 30/70 or more, more preferably 40/60 or more, still more preferably 50/70 or more, from the viewpoint of dispersion stability and pumpability of the calcium carbonate powder and lowering the viscosity of the dispersion liquid of the composition. It is 50 or more, and preferably 90/10 or less, more preferably 80/20 or less, and further preferably 70/30 or less. In the above case, it is not excluded that a small amount, for example, 1% by mass or less of the unmodified CNF in the solid content of the composition is contained.
Further, when the composition of the present invention contains a modified CNF and an unmodified CNF, that is, when it contains a modified CNF and an unmodified CNF without containing pulp fibers, it is unmodified with respect to the modified CNF in the composition. The mass ratio of CNF (unmodified CNF / modified CNF) is preferably 30/70 or more, more preferably 40, from the viewpoint of dispersion stability of calcium carbonate powder, pumpability, and reduction of viscosity of the dispersion liquid of the composition. It is / 60 or more, more preferably 50/50 or more, and preferably 90/10 or less, more preferably 80/20 or less, still more preferably 70/30 or less. In the above case, it is not excluded that a small amount of pulp fiber, for example, 1% by mass or less of the solid content of the composition is contained.

When the composition of the present invention contains modified CNF, pulp fiber and unmodified CNF, the total mass ratio of pulp fiber and unmodified CNF to the modified CNF in the composition ((pulp fiber + unmodified CNF) / modified CNF) is preferably 30/70 or more, more preferably 40/60 or more, still more preferably 50/50 or more, from the viewpoint of dispersion stability of calcium carbonate, pumpability, and lowering the viscosity of the dispersion liquid of the composition. And preferably 90/10 or less, more preferably 80/20 or less, still more preferably 70/30 or less.

(viscosity)
In the present invention, the viscosity of the dispersion (slurry) in which the composition is adjusted to a solid content concentration of 0.4% (0.4% by mass) at 23 ° C. is a viewpoint of improving handleability in actual use, and From the viewpoint of further improving the dispersion stability of the calcium carbonate powder, it is preferably 100 mPa · s or more, more preferably 125 mPa · s or more, still more preferably 150 mPa · s or more, and from the same viewpoint, preferably 3, It is 000 mPa · s or less, more preferably 2,000 mPa · s or less, still more preferably 1,500 mPa · s or less, still more preferably 1,000 mPa · s or less, still more preferably 500 mPa · s or less.
The above viscosity is determined by stirring the slurry in which the solid content concentration of the composition is adjusted to 0.4% at 1500 rpm for 5 minutes with a disperser, and then before measurement in an environment of 23 ° C. and 50% relative humidity for 24 hours. After allowing to stand, the measurement is performed using a B-type viscometer under the conditions of 23 ° C. and a rotation speed of 3 rpm. More specifically, for example, an analog viscometer T-LVT manufactured by BLOOKFIELD, which is a B-type viscometer, can be used. The measurement conditions are, for example, a liquid temperature of 23 ° C. and a viscometer rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement is taken as the viscosity of the dispersion liquid. The composition may be completely dissolved or dispersed in the dispersion.
The solvent of the dispersion is preferably an aqueous medium, and the content of water is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.
When the composition of the present invention contains components other than modified CNF, pulp fiber, and unmodified CNF, for example, a pigment, an antioxidant, a pH adjuster, etc., which will be described later, the modified CNF, pulp fiber, and the like. It is preferable that the viscosity in a state containing only unmodified CNF is within the above range. Alternatively, if it contains components other than modified CNF, pulp fiber, and unmodified CNF, but it is difficult to remove the other components, the total solid content of modified CNF, pulp fiber, and unmodified CNF. The viscosity of the dispersion adjusted to 0.4% is preferably in the above range.

[Preceding agent for pumping concrete pump]
The composition of the present invention is used to mix with calcium carbonate powder to produce a precursor for pumping concrete pumps.
In the present invention, the preceding agent for pumping a concrete pump is usually in the form of powder or paste, and is dispersed by adding water before use, and is charged into the hopper of the concrete pump as a dispersion liquid obtained thereby. The "preceding agent for pumping concrete pump" does not mean only a powdery state, but also means a dispersion liquid dispersed in water.
Therefore, in the present invention, the composition may be in the form of a powder such as a wet powder, mixed with calcium carbonate, and may exist as a powdery precursor for pumping as a whole, and the composition is dispersed. It is in a liquid state (slurry), and when a powder containing calcium carbonate powder is used as an aqueous dispersion, a dispersion containing the composition (slurry) is added and mixed with the calcium carbonate powder to prepare a precursor. (Dispersion liquid) may be used. Among these, from the viewpoint of ease of handling and ease of stirring, it is preferable to add a dispersion containing the composition to calcium carbonate powder or a slurry thereof and mix them to prepare a precursor.

In the present invention, the mixing amount of the composition with respect to 100 parts by mass of the calcium carbonate powder is preferably 0.0001 parts by mass or more, more preferably 0.001 parts by mass, from the viewpoint of obtaining a precursor having excellent dispersion stability and pumping property. The above is more preferably 0.01 parts by mass or more, and from the same viewpoint, preferably 0.1 parts by mass or less, more preferably 0.05 parts by mass or less, still more preferably 0.03 parts by mass or less. Even more preferably, it is 0.02 parts by mass or less.
The mixed amount of the composition means the mixed amount as a dried composition.

In the present invention, the precursor contains at least calcium carbonate powder.
The content of the calcium carbonate powder in the solid content of the precursor is preferably 50% by mass, more preferably 60% by mass or more, and further, from the viewpoint of excellent dispersibility and pumping property and suppressing clogging of the concrete pipe. It is preferably 70% by mass or more, more preferably 80% by mass or more, and preferably 99.9% by mass or less.

The calcium carbonate powder may be a light calcium carbonate component such as precipitated calcium carbonate, or a heavy calcium carbonate powder obtained by crushing limestone, and is not particularly limited, but as a precursor. From the viewpoint of obtaining excellent performance, it is preferable that the calcium carbonate powder has a small particle size. Further, calcium carbonate powder whose particle size and composition have been adjusted may be used.
Among these, it is preferable to contain porous calcium carbonate powder from the viewpoint of exhibiting excellent performance as a precursor. Examples of the porous calcium carbonate include porous calcium carbonate powder obtained by adjusting the particle size and composition of raw consladge.
Further, the calcium carbonate powder may contain fine powdered calcium carbonate having a uniform particle shape, such as precipitated calcium carbonate.

In the present invention, the precursor may contain other components in addition to the calcium carbonate powder and the composition of the present invention.
Examples of other components include inorganic powders other than calcium carbonate powder, water-absorbent resins, water-soluble resins, pigments, antioxidants, pH adjusters, and the like. The composition of the present invention is more preferably mixed with at least one selected from the group consisting of pigments, antioxidants and pH regulators.
Examples of the inorganic powder other than the calcium carbonate powder include calcium hydroxide, hydrotalcite, and calcium oxide. Further, the pigment may be either an inorganic pigment or an organic pigment. By containing the pigment, the visibility of the preceding agent to be discharged is improved, and it becomes easy to monitor the end of discharge of the preceding agent. As the organic pigment, an organic fluorescent pigment is particularly preferable from the viewpoint of visibility.
Further, an antioxidant such as erythorbic acid or a pH adjusting agent may be added for the purpose of preventing oxidation and adjusting the pH. By adding an antioxidant, a pH adjuster, or the like, the dispersibility of the preceding agent is further improved, and the effects of corrosion in the piping and mixing with concrete are reduced.

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

The modified CNF, unmodified CNF and pulp fiber used in each Example and Comparative Example are as follows.
[Production Example 1: Preparation of Phosphate Group Introduced Pulp Dispersion]
(Preparation of phosphoric acid group-introduced pulp)
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 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 phosphorylated as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp is heated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphate group into the cellulose in the pulp, and the phosphate group-introduced pulp (hereinafter, also referred to as “phosphorylated pulp”) is obtained. Obtained. Then, the obtained phosphorylated pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. went. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.
Next, the phosphorylated pulp after washing was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated to obtain a phosphorylated pulp that had been neutralized. Next, the phosphorylated pulp after the neutralization treatment was subjected to the above washing treatment.
The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption based on the phosphate group was observed around 1230 cm ^-1 , and it was confirmed that the phosphate group was added to the pulp. The amount of phosphoric acid group (strongly acidic group amount) measured by the measuring method described later was 1.45 mmol / g. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.
The obtained pulp diluted so as to have a solid content concentration of 2% by mass was used. The fiber width of the pulp fiber was measured using a Kajaani fiber length measuring machine (FS-200, manufactured by Kajaani Automation Co., Ltd.) and found to be 30 μm.

[Production Example 2: Preparation of fine fibrous modified cellulose dispersion having a phosphoric acid group]
(Preparation of phosphoric acid group-introduced pulp)
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 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 phosphorylated as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphate group into the cellulose in the pulp to obtain a phosphate group-introduced pulp (phosphorylated pulp). Then, the obtained phosphorylated pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. went. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set. The phosphorylated pulp after washing was further subjected to the above phosphorylation treatment and the above washing treatment once in this order.
Next, the phosphorylated pulp after washing was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated to obtain a phosphorylated pulp that had been neutralized. Next, the phosphorylated pulp after the neutralization treatment was subjected to the above washing treatment.
The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption based on the phosphate group was observed around 1230 cm ^-1 , and it was confirmed that the phosphate group was added to the pulp. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

(Preparation of fibrous cellulose dispersion)
Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a modified CNF dispersion liquid 1 containing fine fibrous modified cellulose. By X-ray diffraction, it was confirmed that the fine fibrous modified cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous modified cellulose was measured using a transmission electron microscope, it was 3 to 5 nm.
The amount of phosphate groups (first dissociation amount) of the fine fibrous modified cellulose measured by the measurement method described later was 2.00 mmol / g, and the degree of polymerization was 444.

(Production Example 3: Preparation of fine fibrous modified cellulose dispersion having a phosphorous acid group)
(Preparation of phosphite-introduced pulp)
The same operation as in Production Example 1 was carried out except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate, and the phosphorous acid group-introduced pulp (hereinafter, also referred to as “phosphorylated pulp”) was used. I got.).
Then, the obtained subphosphorylated pulp was washed. In the washing treatment, the pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of subphosphorylated pulp is stirred so that the pulp is uniformly dispersed, and then filtration and dehydration are repeated. I went by. When the electric conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.
Next, the washed subphosphorylated pulp was neutralized as follows. First, the washed subphosphorylated pulp is diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution is added little by little with stirring to obtain a subphosphorylated pulp slurry having a pH of 12 or more and 13 or less. Obtained. Next, the subphosphorylated pulp slurry was dehydrated to obtain a neutralized subphosphorylated pulp. Next, the subphosphorylated pulp after the neutralization treatment was subjected to the above washing treatment.
The infrared absorption spectrum of the obtained subphosphorylated pulp was measured using FT-IR. As a result, absorption based on P = O of the phosphonic acid group, which is a tautomer of the phosphite group, was observed around 1210 cm ^-1 , and the phosphite group (phosphonic acid group) was added to the pulp. Was confirmed.
Further, when the obtained subphosphorylated pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals.

(Preparation of fine fibrous modified cellulose dispersion)
Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) 6 times at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous modified cellulose. By X-ray diffraction, it was confirmed that the fine fibrous modified cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous modified cellulose was measured using a transmission electron microscope, it was 3 to 5 nm.
The amount of phosphorous acid groups (first dissociated acid amount) of the fibrous cellulose measured by the measuring method described later was 1.80 mmol / g, and the degree of polymerization was 430.

[Production Example 4: Preparation of fine fibrous modified cellulose dispersion having a carboxy group]
(Preparation of carboxy group-introduced pulp)
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 g / m ² sheets, dissociated and measured according to JIS P 8121 Canadian standard drainage degree (CSF) is 700 mL) It was used. This raw material pulp was subjected to TEMPO oxidation treatment as follows.
First, the raw material pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10 parts by mass of water. It was dispersed in 000 parts by mass. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so as to be 10 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change in pH was observed.
Next, the obtained carboxy group-introduced pulp (hereinafter, also referred to as “TEMPO oxide pulp”) was washed. In the washing treatment, the pulp slurry after TEMPO oxidation is dehydrated to obtain a dehydrated sheet, and then 5,000 parts by mass of ion-exchanged water is poured, stirred and uniformly dispersed, and then filtered and dehydrated is repeated. Was done by. When the electric conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.
Further, when the obtained TEMPO oxide pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

(Preparation of fibrous cellulose dispersion)
Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst) 6 times at a pressure of 200 MPa to obtain a fibrous cellulose dispersion containing fine fibrous modified cellulose.
The amount of carboxy group of the fibrous cellulose measured by the measuring method described later was 1.80 mmol / g, and the degree of polymerization was 336.

[Production Example 5: Production of Fine Fibrous Unmodified Cellulose Dispersion]
Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., solid content 93% by mass, softwood kraft pulp, basis weight 208 g / m ² sheets, dissociated and measured according to JIS P 8121 Canadian standard drainage degree (CSF) ) Was 700 mL), and ion-exchanged water was added to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated 20 times with a wet atomizer (Starburst, manufactured by Sugino Machine Limited) at a pressure of 200 MPa to obtain a fine fibrous cellulose-containing dispersion. The number average fiber width of the fine fibrous cellulose contained in this dispersion was 1000 nm or less.

[Production Example 6: Preparation of Unmodified Pulp Fiber 1 Dispersion]
Coniferous kraft pulp (manufactured by Oji Paper Co., Ltd., solid content 93% by mass, basis weight 208 g / m ² sheets, separated and measured according to JIS P 8121 with a Canadian standard drainage degree (CSF) of 700 mL). The one diluted so that the solid content concentration became 2% by mass was used. The fiber width of the pulp fiber was measured using a Kajaani fiber length measuring machine (FS-200, manufactured by Kajaani Automation Co., Ltd.) and found to be 30 μm.

[Production Example 7: Preparation of Unmodified Pulp Fiber 2 Dispersion]
Coniferous kraft pulp (manufactured by Oji Paper Co., Ltd., solid content 93% by mass, basis weight 208 g / m ² sheets, dissociated and measured according to JIS P 8121 with a Canadian standard drainage degree (CSF) of 700 mL). The mixture was beaten with a double disc refiner until the irregular freeness reached 100 mL to obtain a pulp dispersion having a solid content concentration of 2% by mass. The fiber width of the pulp fiber was measured using a Kajaani fiber length measuring machine (FS-200, manufactured by Kajaani Automation Co., Ltd.) and found to be 15 μm.

<Measurement method>
(Measurement of phosphorus oxo acid group amount in fibrous cellulose dispersion)
The amount of ionic groups of the fine fibrous cellulose contains the modified CNF prepared by diluting the fine fibrous modified cellulose dispersion containing the target modified CNF with ion-exchanged water so that the content is 0.2% by mass. The slurry was treated with an ion exchange resin and then titrated with an alkali to measure the results.
In the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) having a volume of 1/10 is added to the modified CNF-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.
In the 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 modified CNF-containing slurry after treatment with an ion exchange resin every 5 seconds. I went by. Titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of 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 is the amount of phosphorus oxo acid groups (first dissociated acid amount) (mmol / g). ).
For phosphorylated pulp, ion-exchanged water was added to the phosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass, and this slurry was subjected to a wet atomizing device (manufactured by Sugino Machine Co., Ltd., Starburst). ) Was treated 6 times at a pressure of 200 MPa, and the dispersion obtained was subjected to titration using an alkali in the same manner as in the above method.

(Measurement of carboxy group amount in fibrous cellulose dispersion)
The amount of carboxy groups in the fine fibrous cellulose was measured by a neutralization titration method. The amount of carboxy groups in the fine fibrous cellulose is adjusted to 0.2% by mass by adding ion-exchanged water to the fine fibrous cellulose-containing dispersion containing the target fine fibrous cellulose, and treated with an ion exchange resin. After that, the measurement was carried out by performing a titration using an alkali.
For the treatment with an ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; manufactured by Organo Co., Ltd., conditioned) with a volume of 1/10 is added to a dispersion containing 0.2% by mass of fine fibrous cellulose, and 1 After the time-shaking treatment, the resin and the slurry were separated by pouring onto a mesh having a mesh size of 90 μm.
In addition, titration using alkali is performed by measuring the change in pH value indicated by the slurry while adding 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing dispersion after treatment with an ion exchange resin. It was. By observing the change in pH while adding an aqueous sodium hydroxide solution, a titration curve as shown in FIG. 2 can be obtained. As shown in FIG. 2, in this neutralization titration, there is one point in which the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Observed. The maximum point of this increment is called the first end point. Here, the region from the start of titration to the first end point in FIG. 2 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the slurry used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the fine fibrous cellulose-containing dispersion to be titrated, so that the amount of carboxy group introduced (mmol / mmol /). g) was calculated.
The above-mentioned amount of carboxy group introduced (mmol / g) is the amount of substituents per 1 g of mass of fibrous cellulose when the counterion of the carboxy group is hydrogen ion (H ⁺ ) (hereinafter, the amount of carboxy group (acid). Type)) is shown.

(Measurement of degree of polymerization of fibrous cellulose)
The degree of polymerization of the fibrous cellulose was measured according to Tappi T230. That is, after measuring the viscosity (referred to as η ₁ ) measured by dispersing the fibrous cellulose to be measured in a dispersion medium and the blank viscosity (referred to as η ₀ ) measured only with the dispersion medium, the specific viscosity (η). _sp ) and intrinsic viscosity ([η]) were measured according to the following formulas.
η _SP = (η ₁ / η ₀ ) -1
[Η] = η _{sp / (} c (1 + 0.28 × η _sp ))
Here, c in the formula indicates the concentration of fibrous cellulose at the time of viscosity measurement.
Further, the degree of polymerization (DP) of the fibrous cellulose was calculated from the following formula.
DP = 1.75 x [η]
Since this degree of polymerization is the average degree of polymerization measured by the viscosity method, it is sometimes called "viscosity average degree of polymerization".

(Measurement of viscosity of dispersion of composition)
The viscosity of the dispersion of the composition was measured as follows. First, the composition was diluted with ion-exchanged water so that the solid content concentration became 0.4%, and then the mixture was stirred with a disperser at 1,500 rpm for 5 minutes. Next, the viscosity of the dispersion liquid thus obtained was measured using a B-type viscometer (analog viscometer T-LVT manufactured by BLOOKFIELD). The measurement conditions were a rotation speed of 3 rpm, and the viscosity value 3 minutes after the start of measurement was taken as the viscosity of the dispersion. The dispersion to be measured was allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours before the measurement. The liquid temperature of the dispersion liquid at the time of measurement was 23 ° C.

(Preparation of precursor for model pumping)
(Example 1)
100 parts by mass of porous calcium carbonate and 200 parts by mass of water are mixed, and the composition of the present invention containing modified CNF and pulp fiber is added thereto so that the solid content is the amount shown in Table 1. They were mixed to prepare a precursor for model pumping.
As the modified CNF having a phosphoric acid group, the dispersion prepared in Production Example 2 was used. As the pulp fiber, the unmodified pulp fiber 1 dispersion prepared in Production Example 6 was used.

(Examples 2 to 6 and Comparative Examples 1 to 7)
A precursor for model pumping was prepared in the same manner as in Example 1 except that the composition used in Example 1 was changed so as to add the modified CNF, the unmodified CNF, and the pulp fiber shown in Table 1. did.
Here, as the modified CNF, the pulp fiber, and the unmodified CNF, the dispersions obtained in the following production examples were used so that the solid content was each added amount.
-Modified CNF (ionic group: phosphate group): Production Example 2
-Modified CNF (ionic group: phosphite group): Production Example 3
-Modified CNF (ionic group: carboxy group): Production Example 4
-Pulp fiber (unmodified, fiber width = 30 μm): Production Example 6
-Pulp fiber (unmodified, fiber width = 15 μm): Production Example 7
-Pulp fiber (introduced phosphate group, fiber width = 30 μm): Production Example 1
-Unmodified CNF: Production Example 5

(Reference example)
A precursor for model pumping was prepared in the same manner as in Example 1 except that water was used instead of the modified CNF and pulp fibers.

<Evaluation method>
(Dispersion stability evaluation)
The model pumping precursors of Examples, Comparative Examples, and Reference Examples were diluted with ion-exchanged water so as to have a solid content concentration of 1%, and separated into a 10 mL screw vial bottle (manufactured by AS ONE Corporation) for 5 minutes. It was left still. The distance from the bottom of the vial to the liquid level was 3 cm. The dispersion stability was evaluated according to the following evaluation criteria. The results are shown in Table 1.
A: Shows good dispersion stability without separation at all B: Shows good dispersion stability with almost no separation C: Shows dispersion stability with some separation but no problem in use D: Separation with time was observed and could not be used. E: Significant separation was observed and could not be used. In Comparative Examples 1 to 3 and 5, the viscosity could not be measured because the pulp fibers settled. In addition, reference example 1 was not measured.
In addition, for Examples 1, 5, and 6, and Comparative Examples 1 and 7, the distance between the liquid level in the screw bottle and the interface between water generated by the separation was measured. The results are shown in Table 2.

[result]
As shown in Table 1, in the diluted solutions of the precursors for pumping the models of Examples 1, 3, 5 and 6, calcium carbonate was not separated with time, and good dispersion stability was shown. Also, in Example 4, good dispersion stability was shown with almost no separation. Further, as in Comparative Examples 6 and 7, when only the modified CNF was used, although dispersion stability was observed, the viscosity of the composition was high and the handleability in actual use was inferior. On the other hand, as shown in Examples 1 to 6, by using at least one selected from unmodified CNF and pulp fiber in combination with the modified CNF, the viscosity of the composition is maintained while maintaining sufficient dispersion stability. Was able to be reduced, and the handleability during actual use was significantly improved. On the other hand, in Comparative Examples 1 to 3 and 5, sufficient dispersion stability could not be obtained. Further, in Comparative Example 4 in which the unmodified CNF and the pulp fiber were used in combination, the dispersion stability was obtained, but the dispersion stability over time was inferior to that in the example in which the modified CNF was used.
Further, as shown in Table 2, the distance between the liquid level in the screw bottle and the boundary surface between the water generated by the separation is significantly shorter in Examples 1, 5 and 6 than in Comparative Examples 1 and 7. It was shown that even if it was left to stand for a long time, it suppressed separation and showed high dispersion stability.
From the above results, in the pumping precursor to which the composition containing the modified CNF and at least one selected from the unmodified CNF and the pulp fiber was added, the dispersion stability of calcium carbonate was improved and the composition was improved. It was shown that the viscosity is low and the handleability in actual use is excellent.

(Evaluation of pumpability)
A 50 mL disposable syringe (manufactured by Terumo Corporation) was packed with 10 g of Examples 1, 5 and 6, Comparative Examples 1, 2 and 7, and the model pumping precursor of Reference Example, and the time required for extrusion of the entire amount was measured. .. The extrusion pressure at this time was about 0.1 kPa. The results are shown in Table 3.

[result]
Examples 1, 5 and 6 showed that the required time was 60 seconds or less and could be extruded smoothly, suggesting that the calcium carbonate powder was effectively dispersed and stabilized. On the other hand, in Comparative Examples 1, 2 and 7, and Reference Example, an extrusion time of 120 seconds or more (twice or more that of Examples) was required.
The pumping precursor containing the modified CNF of the present invention and a composition containing at least one selected from pulp fibers and unmodified CNF has excellent dispersion stability and can be pumped at a lower pressure during pumping. Furthermore, it was shown that the composition has a low viscosity and is excellent in handleability in actual use.

The composition of the present invention can provide a concrete pump pumping precursor containing calcium carbonate powder, which is excellent in dispersion stability and pumping property, and also excellent in handling property in actual use, and can be used in a small amount. Therefore, it is expected that the pumping of concrete through the piping will start smoothly.

Claims (8)

A composition used for producing a precursor for pumping concrete pumps by mixing with calcium carbonate powder.
The composition comprises fine fibrous modified cellulose having an ionic group and a fiber width of 1,000 nm or less, pulp fibers having a fiber width of 10 μm or more, and a fiber width of 1,000 nm or less, and ions. A composition comprising at least one selected from the group consisting of fine fibrous cellulose having no sex group. The composition according to claim 1, wherein the viscosity of the composition (solid content concentration 0.4% dispersion, 23 ° C.) is 100 mPa · s or more and 3000 mPa · s or less. The composition contains pulp fibers having a fiber width of 10 μm or more, and the mass ratio of the pulp fibers to the fine fibrous modified cellulose (pulp fiber / fine fibrous modified cellulose) is 30/70 or more and 90/10. The composition according to claim 1 or 2, which is as follows. The composition contains the fine fibrous cellulose having no ionic group, and the mass ratio of the fine fibrous cellulose not containing the ionic group to the fine fibrous modified cellulose (fine fiber not containing an ionic group). The composition according to claim 1 or 2, wherein the amount of cellulose (like cellulose / fine fibrous modified cellulose) is 30/70 or more and 90/10 or less. The composition according to any one of claims 1 to 4, wherein the content of the calcium carbonate powder in the solid content of the preceding agent for pumping concrete pump is 50% by mass or more. The composition according to any one of claims 1 to 5, wherein the mixed amount of the composition with respect to 100 parts by mass of the calcium carbonate powder is 0.0001 parts by mass or more and 0.1 parts by mass or less. The composition according to any one of claims 1 to 6, wherein the calcium carbonate powder contains a porous calcium carbonate powder. The composition according to any one of claims 1 to 7, further mixed with at least one selected from pigments, antioxidants, and pH regulators.