JP2020172461A - Powdery liquid - Google Patents

Abstract

To provide a powdery liquid having excellent manufacturability and stability.SOLUTION: A powdery liquid according to one embodiment has such a structure that: a liquid component, in which a nano cellulose material having a cellulose I-type crystal structure is dispersed in aqueous liquid, is coated with hydrophobic fine particles.SELECTED DRAWING: None

Description

The present invention relates to powdered liquids.

A powdery liquid (also referred to as a dry liquid) powdered by coating a liquid with fine particles is known. When the liquid is water, it is also called dry water. Although the powdery liquid is in the powdery form, it contains a large amount of liquid, and therefore liquefies when rubbed during use. Therefore, its use in cosmetics has been proposed.

For example, a liquid component in which a water-soluble polymer such as a cellulose derivative or a polysaccharide is dissolved in water and a powdered cosmetic (dry water) prepared by using hydrophobic silica are known (see Patent Document 1). ..

Japanese Unexamined Patent Publication No. 2006-335670

Bernard P. Binks and Ryo Murakami. Phase inversion of particles-stabilized materials from foams to dry water. Nature Materials 5,865-869 (2006)

Conventionally, in the production of a powdery liquid, when the liquid component is coated with fine particles and powdered, it is necessary to perform strong mixing and stirring. Therefore, there is a problem that a special device such as a stirrer or a high-speed blender is required, and a large amount of power cost is required, which makes the manufacturing device complicated and increases the manufacturing cost. Further, there is a problem that the obtained powdery liquid is unstable.

An embodiment of the present invention aims to provide a powdery liquid having excellent manufacturability and stability.

The powdery liquid according to the embodiment of the present invention is characterized in that a liquid component obtained by dispersing a nanocellulose material having a cellulose I-type crystal structure in an aqueous liquid is coated with hydrophobic fine particles. ..

According to the embodiment of the present invention, it is possible to provide a powdery liquid having excellent manufacturability and stability.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The powdery liquid according to the present embodiment is a liquid component obtained by dispersing a nanocellulose material having a cellulose I-type crystal structure in an aqueous liquid, and is coated with hydrophobic fine particles. By dispersing the nanocellulose material having a cellulose I-type crystal structure in an aqueous liquid, high pseudoplastic fluidity can be imparted to the liquid component. Here, the pseudoplastic fluidity is a property of having a high viscosity in a low shear region and a low viscosity in a high shear region. Therefore, in the production of powdered liquid, the viscosity can be easily reduced when the liquid components are stirred, and the powdered liquid can be easily produced even by simple mixing and stirring such as manual mixing without using a powerful mixing and stirring device. be able to. In addition, since the water-dispersible nanocellulose material acts on the interface between the hydrophobic fine particles and the liquid component, it is possible to suppress the desorption of the hydrophobic fine particles and the liquefaction due to the collision between the powdery liquids. Improves the stability of powdered liquids. The result is a powdery liquid with high manufacturability and stability.

[Nanocellulose material]
The nanocellulose material is a cellulose material having a cellulose type I crystal structure and a nanometer-level width (that is, a number average width of less than 1000 nm). By having the cellulose type I crystal structure in this way, the nanocellulose material is insoluble in water and is therefore water-dispersible. The fact that the cellulose constituting the nanocellulose material has an I-type crystal structure means that, for example, in the diffraction profile obtained by wide-angle X-ray diffraction image measurement, 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °. It can be identified by having typical peaks at the two positions of.

The number average width of the nanocellulose material is preferably 2 to 500 nm, more preferably the upper limit is 200 nm or less, further preferably 100 nm or less, and may be 50 nm or less.

The number average width of the nanocellulose material is generally the number average width of the short width side of the nanocellulose material having a short width and a long width, and is also referred to as a number average fiber diameter. The number mean width can be measured as follows. That is, an aqueous dispersion of a nanocellulose material having a solid content of 0.05 to 0.1% by mass is prepared, and the aqueous dispersion is cast on a hydrophilized carbon film-coated grid to be a permeation type. Use as an observation sample of an electron microscope (TEM). When a fiber having a large fiber diameter (nanocellulose material) is contained, a scanning electron microscope (SEM) image of the surface cast on glass may be observed. Further, the observation sample may be negatively stained with, for example, a 2% by mass uranyl acetate aqueous solution. Then, observation is performed using an electron microscope image at a magnification of 5000 times, 10000 times, or 50,000 times depending on the size of the constituent fibers. At that time, an axis having an arbitrary vertical and horizontal image width is assumed in the obtained image, and the sample and observation conditions (magnification, etc.) are adjusted so that 20 or more fibers intersect the axis. Then, after obtaining an observation image satisfying this condition, two random axes in each of the vertical and horizontal directions are drawn with respect to this image, and the short width (fiber diameter) of the fibers intersecting the axes is visually observed. I will read it. In this way, images of at least three non-overlapping surface portions are taken with an electron microscope and the short width values of the fibers intersecting each of the two axes are read (thus, at least 20 fibers x 2 x 3 = 120). You can get short information about the book). The short arithmetic mean obtained in this way is defined as the number mean width.

More specifically, the nanocellulose materials include (1) cellulose nanofibers having a number mean width of 2 nm or more and less than 1000 nm and an aspect ratio of 50 or more, and (2) a number average width of 2 nm or more and less than 1000 nm and an aspect ratio. Examples include less than 50 cellulose nanocrystals.

The number average width of the cellulose nanofibers is preferably 2 to 500 nm, more preferably the upper limit is 200 nm or less, further preferably 100 nm or less, and may be 50 nm or less. The aspect ratio of the cellulose nanofibers is preferably 50 to 1000, more preferably 100 to 1000, and even more preferably 200 to 500.

The method for measuring the number average width of the cellulose nanofibers is as described above for the nanocellulose material. The aspect ratio of the cellulose nanofibers can be measured as follows. That is, the number mean width is calculated according to the method described above. Further, from the same observation image, the number average fiber length, which is the number average width of the long width of the nanocellulose material, is calculated. Specifically, at least 10 long widths (fiber lengths) from the start point to the end point of the fibers are visually read. For branched fibers, the length of the longest portion of the fiber is defined as the long width. The arithmetic mean of the length widths thus obtained is calculated and used as the number average fiber length. Using these values, the aspect ratio is calculated according to the following formula.
Aspect ratio = number average fiber length (nm) / number average width (number average fiber diameter) (nm)

The surface of the cellulose nanofibers is preferably chemically modified. Examples of chemical modifications include the introduction of nonionic, anionic, cationic or amphoteric groups. From the viewpoint of being able to maintain the type I crystal structure and efficiently defibrating fibers up to the nanometer level, anion-modified or cation-modified cellulose nanofibers are preferable, and anion-modified is more preferable. That is, it is preferable that the anion-modified cellulose nanofiber has an anionic group introduced into the glucose unit in the cellulose molecule.

Examples of the anionic group include at least one selected from the group consisting of a carboxy group, a phosphoric acid group, a sulfonic acid group, and a sulfate group. In the present specification, the carboxy group is a concept including not only an acid type (-COOH) but also a salt type, that is, a carboxylic acid base (-COOX, where X is a cation forming a salt with a carboxylic acid). Acid type and salt type may be mixed. Similarly, the phosphate group, the sulfonic acid group, and the sulfate group are concepts that include not only the acid type but also the salt type, and the acid type and the salt type may be mixed.

The anionic group salt is not particularly limited, but includes alkali metal salts such as sodium salt, potassium salt and lithium salt, alkaline earth metal salts such as magnesium salt, calcium salt and barium salt, ammonium salt and phosphonium salt. Examples thereof include onium salts, primary amines, secondary amines, and amine salts such as tertiary amines.

The content of anionic groups (for example, carboxy groups) in the anion-modified cellulose nanofibers is not particularly limited, and may be 0.2 mmol / g or more, or 0.5 mmol / g or more, per dry mass of the cellulose nanofibers. It may be 1.0 mmol / g or more. Further, it may be 2.5 mmol / g or less, or 2.0 mmol / g or less. The content of anionic groups can be determined by measuring the electrical conductivity. For example, a cellulose nanofiber-containing slurry prepared to a concentration of about 0.05 to 1% by mass is neutralized with an aqueous solution of sodium hydroxide to neutralize it. It can be calculated by the following formula using the amount V (mL) of the aqueous sodium hydroxide solution consumed in the step and the molar concentration c (mol / L) of the aqueous sodium hydroxide solution.
Anionic group amount (mmol / g) = V × [c / cellulose sample mass (g)]

In one embodiment, the anionic group is preferably a carboxy group. Examples of the cellulose nanofibers containing a carboxy group include the oxidized cellulose nanofiber (A) formed by oxidizing the hydroxyl group of the glucose unit in the cellulose molecule and the carboxymethyl formed by carboxymethylating the hydroxyl group of the glucose unit in the cellulose molecule. Examples thereof include celluloseized nanofibers (B).

As the cellulose oxide nanofiber (A), it is preferable to use one in which the hydroxyl group at the C6 position of the glucose unit in the cellulose molecule is selectively oxidized and modified to a carboxy group. Here, it can be confirmed by, for example, the ¹³ C-NMR chart that the hydroxyl group at the 6-position was selectively oxidized. The cellulose oxide nanofiber (A) may have an aldehyde group or a ketone group together with a carboxy group, that is, the C6 position of the glucose unit may become a carboxy group by oxidative modification, but an aldehyde group. Alternatively, it may become a ketone group, or may contain a hydroxyl group that remains unmodified.

The oxidized cellulose nanofiber (A) can be obtained, for example, by oxidizing natural cellulose such as wood pulp with an cooxidant in the presence of an N-oxyl compound and defibrating (refining) it. As the N-oxyl compound, a compound having a nitroxy radical generally used as an oxidation catalyst is used, for example, a piperidine nitroxyoxy radical, and particularly 2,2,6,6-tetramethylpiperidinooxy radical (TEMPO). ) Or 4-acetamide-TEMPO is preferred.

The carboxymethylated cellulose nanofiber (B) is, for example, subjected to alkali treatment in a mixed solvent of a lower alcohol and water using the above-mentioned natural cellulose as a raw material, and then an etherification reaction is carried out by adding a carboxymethylating agent. After that, it is obtained by defibrating (refining) treatment.

Cellulose nanofibers are usually obtained by performing a defibration treatment. The defibration treatment is preferably carried out after introducing an anionic group. The defibration treatment can be performed using, for example, a homomixer under high-speed rotation, a high-pressure homogenizer, an ultrasonic dispersion processing machine, a beater, a disc type refiner, a conical type refiner, a double disc type refiner, a grinder, or the like.

Cellulose nanocrystals have a shorter fiber length than cellulose nanofibers, and are obtained, for example, by acid-hydrolyzing cellulose fibers with sulfuric acid or the like and then defibrating them into nanofibers. However, it is not limited to that obtained by this manufacturing method.

The number average width of the cellulose nanocrystals is preferably 2 to 500 nm, more preferably the upper limit is 200 nm or less, still more preferably 100 nm or less, and may be 50 nm or less. The aspect ratio of the cellulose nanocrystals is preferably 40 or less, and may be 30 or less. The lower limit of the aspect ratio of the cellulose nanocrystal is not particularly limited, and may be, for example, 5 or more, or 10 or more. The method for measuring the number average width and aspect ratio of cellulose nanocrystals is the same as that for cellulose nanofibers.

[Aqueous liquid]
The aqueous liquid is a dispersion medium for dispersing the water-dispersible nanocellulose material and contains water. The aqueous liquid may be water alone or may contain a substance that dissolves in water together with water. That is, the aqueous liquid is not limited to water, but may be an aqueous solution. Examples of the substance that dissolves in water include water-soluble organic compounds and water-soluble inorganic compounds, and are not particularly limited. For example, a polar organic solvent (for example, a polyfunctional alcohol such as glycerol, methanol, ethanol, isopropanol, or the like is simply used. Functional alcohols, ethers such as tetrahydrofuran, ketones such as acetone and methyl ethyl ketone), inorganic salts, inorganic acids, inorganic bases, organic acids and salts thereof, water-soluble polymers and the like.

The aqueous liquid preferably contains 80 to 100% by mass of water, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, based on the total mass of the aqueous liquid. It contains the water of 100% by mass of water.

[Liquid component]
The liquid component is a component that becomes a liquid phase in a powdery liquid, and is a dispersion liquid obtained by dispersing a nanocellulose material in an aqueous liquid as described above. The content of the nanocellulose material contained in the liquid component is not particularly limited, but is preferably 0.1 to 5.0% by mass, with the total mass of the liquid component being 100% by mass, and more preferably 0. It is 2 to 3.0% by mass.

The content of the liquid component in the powdery liquid is not particularly limited, but is preferably 40 to 99.9% by mass, with the total mass of the powdery liquid as 100% by mass, and more preferably 50% by mass or more. It is more preferably 70% by mass or more, particularly preferably 80% by mass or more, and may be 90% by mass or more. The upper limit is more preferably 99% by mass or less, still more preferably 98% by mass or less.

[Hydrophobic fine particles]
Hydrophobic fine particles are components that coat the surface of the liquid component, and are substances that enable the formation of a powdery liquid that is a powdery substance containing the liquid component.

As the hydrophobic fine particles, not only those in which the fine particles themselves are hydrophobic but also hydrophobicized fine particles obtained by hydrophobizing the surface of the particles may be used. Here, hydrophobicity refers to a property having a small interaction with water and a small affinity with water. Examples of the hydrophobic fine particles that are hydrophobic in themselves include organic fine particles such as polyamide resin powder, polyethylene powder, and polystyrene powder. Examples of the hydrophobized fine particles include those obtained by hydrolyzing inorganic fine particles such as talc, kaolin, silica, zeolite, magnesium carbonate, and calcium carbonate. Examples of the method of hydrophobizing treatment include a method of covering the surface of inorganic fine particles with an organosilane compound, a silicone compound, or the like.

Among these, as the hydrophobic fine particles, hydrophobized silica fine particles such as hydrophobic fumed silica fine particles are preferably used.

The average primary particle diameter of the hydrophobic fine particles is not particularly limited, but is preferably 1 to 500,000 nm, more preferably 2 to 50,000 nm, still more preferably 4 to 5000 nm. In one embodiment, the average primary particle size may be 5 to 1000 nm or 5 to 100 nm. These average primary particle diameters are determined by adding hydrophobic fine particles and surfactants to water and then uniformly dispersing them by ultrasonic irradiation, and then using a laser diffraction type particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation). It can be obtained as a weight average value by using.

It is preferable that the hydrophobic fine particles have a wetting time of 100 seconds or more according to the following test method. This wetting time is an index of hydrophobicity, and the wetting time is more preferably 300 seconds or more. The upper limit of the wetting time is not particularly limited, and if it is 600 seconds or more, the test is terminated at that point as being sufficiently hydrophobic.
Test method: After adding 10.0 g of pure water to a 30 ml glass vial at 25 ° C, take 0.1 g of hydrophobic fine particles and gently add to the top of the pure water, and all the hydrophobic fine particles will sink into the water and be placed on the top. The time until the floating hydrophobic fine particles disappear is measured as the wetting time.

The content of the hydrophobic fine particles in the powdery liquid is not particularly limited, but is preferably 0.1 to 60% by mass, with the mass of the liquid component being 100% by mass, and more preferably the lower limit is 1% by mass or more. It is more preferably 2% by mass or more, and the upper limit is more preferably 50% by mass or less, further preferably 30% by mass or less, particularly preferably 20% by mass or less, and may be 10% by mass or less. ..

[Powdered liquid]
The powdery liquid is a liquid component obtained by dispersing the nanocellulose material in an aqueous liquid and is coated with hydrophobic fine particles, and has a powdery form. That is, the liquid component is pulverized in a state where hydrophobic fine particles are adsorbed around the liquid component. When a force is applied to such a powdery liquid by, for example, rubbing it during use, this adsorbed state is destroyed and the powdered liquid component oozes out to liquefy.

The average particle size of the powdery liquid is not particularly limited, but is preferably 10 to 5000 μm, more preferably 20 to 3000 μm, for example. The average particle size can be determined using a 3D digital fine scope (VC1000, manufactured by OMRON). That is, the particle size of 25 or more powdery liquids can be measured by observing an image and obtained as an average value thereof.

The powdery liquid according to the present embodiment may contain other components. For example, another water-insoluble substance may be added and dispersed together with the nanocellulose material to the above liquid component. Further, the liquid component may be coated with another powder together with the above-mentioned hydrophobic fine particles.

The method for producing a powdery liquid according to the present embodiment is not particularly limited as long as it is powdered by coating the liquid component with hydrophobic fine particles. For example, by mixing and stirring a dispersion liquid (liquid component) in which the nanocellulose material is dispersed in an aqueous liquid and hydrophobic fine particles, the liquid component is made into fine water droplets, and the surface of the fine water droplets is hydrophobic. The fine particles can be uniformly adsorbed, and the powdery liquid can be obtained.

The use of the powdered liquid according to the present embodiment is not particularly limited, and it can be used as dry water or a dry liquid in the same manner as before, for example, in cosmetics, pharmaceuticals, foods, paints, pesticides and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Production Example 1: Production of Cellulose Nanofiber 1]
To 2 g of coniferous pulp, 150 ml of water, 0.25 g of sodium bromide, and 0.025 g of TEMPO were added, and after sufficiently stirring and dispersing, a 13 mass% sodium hypochlorite aqueous solution (cooxidant) was added. The amount of sodium hypochlorite was added to 1.0 g of pulp so as to be 6.5 mmol / g, and the reaction was started. The temperature was maintained at 10 ° C. during the reaction. Since the pH decreases as the reaction progresses, the reaction was carried out while dropping a 0.5 N sodium hydroxide aqueous solution so as to maintain the pH at 10 to 11 until no change in pH was observed (reaction time: 120 minutes). ). After completion of the reaction, 0.1N hydrochloric acid was added to adjust the pH to 2 or less, and then filtration and washing with water were repeated for purification.

After purification, pure water was added to adjust the solid content concentration to 2% by mass. Then, the pH of the slurry was adjusted to 10 with a 24 mass% NaOH aqueous solution. The temperature of the slurry was set to 30 ° C., 0.2 mmol / g of sodium borohydride was added to the cellulose fibers, and the mixture was reacted for 2 hours for reduction treatment. After the reaction, 0.1N hydrochloric acid was added to adjust the pH to 2 or less, and then filtration and washing with water were repeated for purification. Pure water was added thereto, and the final concentration was adjusted to 2% by mass of cellulose fibers and the balance was water. 24% by mass sodium hydroxide was added thereto to adjust the pH to 7. This was defibrated by treating it three times at a pressure of 100 MPa using a high-pressure homogenizer (manufactured by Sanwa Engineering Co., Ltd., H11) to obtain an aqueous dispersion of cellulose nanofiber 1.

The obtained cellulose nanofiber 1 was a TEMPO oxidized cellulose nanofiber, and the content of the carboxy group was 1.8 mmol / g. The number average width of the cellulose nanofiber 1 was 4 nm, and the aspect ratio was 250. When the crystal structure of cellulose contained in the cellulose nanofiber 1 was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes". Further, the peak of 62 ppm corresponding to the C6 position of the primary hydroxyl group of the glucose unit, which can be confirmed on the ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead, the peak derived from the carboxyl group at 178 ppm disappears. Was appearing. Therefore, it was confirmed that only the C6-position hydroxyl group of the glucose unit was oxidized to the carboxy group.

[Production Example 2: Production of Cellulose Nanofiber 2]
100 g of softwood pulp was placed in a mixed solution of 435 g of isopropanol (IPA), 65 g of water and 9.9 g of NaOH, and the mixture was stirred at 30 ° C. for 1 hour. To this slurry system, 23.0 g of an IPA solution of 50 mass% monochloroacetic acid was added, the temperature was raised to 70 ° C., and the reaction was carried out for 1.5 hours. The resulting reaction was washed with 80% methanol, then replaced with methanol and dried to produce carboxymethylated cellulose fibers. Next, pure water is added to the carboxymethylated cellulose fiber to dilute it to 2% by mass, and the cellulose is defibrated by treating once with a high-pressure homogenizer (manufactured by Sanwa Engineering Co., Ltd., H11) at a pressure of 100 MPa. An aqueous dispersion of nanofiber 2 was obtained.

The obtained cellulose nanofiber 2 was a carboxymethylated cellulose nanofiber, and the content of the carboxy group was 0.5 mmol / g. The number average width of the cellulose nanofibers 2 was 10 nm, and the aspect ratio was 100. When the crystal structure of cellulose contained in the cellulose nanofiber 2 was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes".

[Production Example 3: Production of Cellulose Nanofiber 3]
According to the method of Example 1 described in paragraph No. 0135 of Japanese Patent No. 5798504, a dehydrated sheet of cellulose fibers into which phosphoroxo acid was introduced was obtained. Distilled water was added to this and stirred to adjust the solid content to 2.0% by mass, and the cellulose nano was defibrated by treating with a high-pressure homogenizer (manufactured by Sanwa Engineering Co., Ltd., H11) three times at 100 MPa. An aqueous dispersion of fiber 3 was produced.

The obtained cellulose nanofiber 3 was a cellulose nanofiber into which a phosphorus oxo acid group was introduced as an anionic group, and the content of the anionic group was 2.5 mmol / g. The number average width of the cellulose nanofibers 3 was 6 nm, and the aspect ratio was 150. When the crystal structure of cellulose contained in the cellulose nanofiber 3 was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes".

[Production Example 4: Production of Cellulose Nanofiber 4]
50 g of softwood pulp was dispersed in 4950 g of water to prepare a dispersion having a pulp concentration of 1% by mass. This dispersion was defibrated by treating with Serendipita MKCA6-3 (manufactured by Masuko Sangyo Co., Ltd.) 20 times to produce an aqueous dispersion of cellulose nanofibers 4.

The obtained cellulose nanofiber 4 was composed of unmodified cellulose having no anionic group, and had a number average width of 50 nm and an aspect ratio of 100. When the crystal structure of cellulose contained in the cellulose nanofiber 4 was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes".

[Production Example 5: Production of Cellulose Nanocrystal 1]
100 g of softwood pulp was taken, suspended in 2 L of a 64 mass% hydrochloric acid aqueous solution, and hydrolyzed at 45 ° C. for 3 hours. After filtering the suspension obtained thereby, 10 L of ion-exchanged water was poured and stirred to uniformly disperse to obtain a dispersion liquid. Then, the step of filtering and dehydrating the dispersion was repeated three times to obtain a dehydrated sheet. Next, the obtained dehydrated sheet was diluted with 10 L of ion-exchanged water, and 1N aqueous sodium hydroxide solution was added little by little with stirring to adjust the pH to about 12. Then, the suspension was filtered and dehydrated, 10 L of ion-exchanged water was added, and the steps of stirring and filtering and dehydrating were repeated twice. Then, ion-exchanged water was added to the obtained dehydrated sheet to prepare a 2% by mass suspension. This suspension was defibrated by treating it 10 times at 100 MPa using a high-pressure homogenizer (manufactured by Sanwa Engineering Co., Ltd., H11) to produce cellulose nanocrystal 1.

The obtained cellulose nanocrystal 1 had a number average width of 20 nm and an aspect ratio of 10. When the crystal structure of cellulose contained in the cellulose nanocrystal 1 was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes".

The measuring method for the characteristics of the nanocellulose material is as follows.
[Measurement of carboxy group amount]
60 ml of an aqueous dispersion in which 0.25 g of a sample is dispersed in water is prepared, the pH is adjusted to about 2.5 with a 0.1 M aqueous hydrochloric acid solution, and then a 0.05 M aqueous sodium hydroxide solution is added dropwise to conduct electrical conduction. The degree was measured. The measurement was continued until the pH reached about 11. From the amount of sodium hydroxide (V) consumed in the neutralization step of a weak acid whose electrical conductivity changes slowly, the amount of carboxy groups (the same applies to those contained as carboxymethyl groups) was determined according to the following formula.
Carboxylic acid group amount (mmol / g) = V (mL) x [0.05 / cellulose sample mass (g)]

[Measurement of phosphate group]
It was measured using conductivity titration according to the method for measuring the amount of a phosphoric acid group introduced into a fiber raw material described in JP-A-2019-2126.

[Number mean width]
The number average width (number average fiber diameter) of the nanocellulose material was observed using a transmission electron microscope (TEM) (JEM-1400, manufactured by JEOL Ltd.). That is, from a TEM image (magnification: 10000 times) negatively stained with a 2 mass% uranyl acetate aqueous solution after the sample was cast on a hydrophilized carbon film-coated grid, the number average width was calculated according to the method described above. Calculated.

[aspect ratio]
From the observation image similar to the measurement of the number average width, the number average fiber length, which is the number average width of the long width of the nanocellulose material, was calculated according to the method described above. Then, the aspect ratio was calculated according to the following formula using the values of the number average width (number average fiber diameter) and the number average fiber length.
Aspect ratio = number average fiber length (nm) / number average width (number average fiber diameter) (nm)

[Crystal structure]
The diffraction profile of the sample is measured using an X-ray diffractometer (RINT-Ultima3, manufactured by Rigaku Co., Ltd.), and is typical of two positions, 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °. When no peak was observed, the crystal structure (type I crystal structure) was evaluated as "present", and when no peak was observed, it was evaluated as "absent".

[Example 1]
The aqueous dispersion of cellulose nanofiber 1 obtained in Production Example 1 was diluted to a solid content concentration of 0.2% by mass to obtain a liquid component. The storage elastic modulus (G': Pa), loss elastic modulus (G ": Pa), and loss tangent (tan δ) at a shear strain of 10% of the liquid component are measured by a rheometer (MCR502, manufactured by Antonio Par, temperature 25 ° C., frequency. Measured using 1 Hz). Then, 10 g of the liquid component was transferred to a 30 mL plastic bottle. Hydrophobicized fumed silica particles (HDK H18, manufactured by Asahikasei-Wacker) as hydrophobic fine particles, wetting time in the hydrophobicity test: A primary average particle size (30 nm) was added for 600 seconds or more so that the amount of hydrophobic fine particles was 4% by mass based on 100% by mass of the liquid component, and the plastic bottle was tightly closed and stirred vigorously up and down for 3 minutes. For the later samples, the availability of the powdery liquid and the stability of the powdery liquid were evaluated.

[Examples 2 to 9]
Except for changing the type of nanocellulose material (cellulose type) and its concentration (cellulose concentration in the liquid component), the type of hydrophobic fine particles and their concentration (particle concentration with respect to 100% by mass of the liquid component) as shown in Table 1. A powdery liquid was prepared and evaluated in the same manner as in Example 1. Details of the hydrophobic fine particles used are as follows.
-Hydrophobic dry silica (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL R8200, wetting time in hydrophobicity test: 600 seconds or more, primary average particle size: 15 nm)
-Acetylene black (manufactured by Denka Co., Ltd., trade name: Denka black, wetting time in hydrophobicity test: 600 seconds or more, primary average particle size: 35 nm)

[Comparative Example 1]
A powdery liquid was prepared in the same manner as in Example 2 except that water-soluble sodium carboxymethyl cellulose (CMC, cellogen BSH-6, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used instead of the nanocellulose material. evaluated.

[Comparative Example 2]
Water alone was used as a liquid component without using a nanocellulose material, and a powdery liquid was prepared and evaluated by the same method as in Example 1 except for the above.

The evaluation method for the availability of the powdery liquid and the stability of the powdery liquid is as follows.
[Preparability of powdered liquid]
The sample was observed with an optical microscope to determine whether or not a powdery liquid having a liquid component coated with hydrophobic fine particles was prepared. When the powdery liquid was observed, it was evaluated as "Yes", and when it was not observed, it was evaluated as "No".

[Stability of powdered liquid]
From the powdered liquid prepared as described above, a powdered liquid having a particle size of about 1 mm was selected, picked up with resin tweezers, placed on the pad of the thumb, and the stability was evaluated by the following method. ..
◎: It can be rolled with the thumb and index finger, and it collapses when strong force is applied.
〇: It is possible to roll with the thumb and index finger, but it collapses without applying strong force while rolling.
Δ: It collapses when it is sandwiched between the thumb and index finger and cannot be rolled.
X: Cannot be taken out with resin tweezers.

The results are as shown in Table 1. In Examples 1 to 9, a powdery liquid could be prepared and the stability was high, although it was a simple manual mixing. In particular, higher stability was obtained when a nanocellulose material having an anionic group, especially a carboxy group introduced therein, was used on the surface. Especially for the powdery liquid with high stability, the value of the loss tangent (calculated by tan δ: G "/ G') of the liquid component used was smaller. That is, it can be said that the property as an elastic body was strong. From this, it is considered that the closer the liquid component is to the elastic body, the more stable the powdery liquid can be obtained.

On the other hand, in Comparative Example 1 in which sodium carboxylmethylcellulose (CMC) was used instead of the nanocellulose material, it was possible to prepare a powdery liquid, but its stability was low. In contrast to dispersible nanocellulose materials that are insoluble in water, CMC is soluble in water. Due to this difference, the action on the interface between the hydrophobic fine particles and the liquid component is different, so it is considered that there is a difference in stability. In Comparative Example 2, the nanocellulose material was not added to the liquid component, and therefore, a powdery liquid could not be prepared by simple manual mixing.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments, omissions, replacements, changes, etc. thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

Claims (5)

A powdery liquid characterized in that a liquid component obtained by dispersing a nanocellulose material having a cellulose I-type crystal structure in an aqueous liquid is coated with hydrophobic fine particles. The nanocellulose material is a cellulose nanofiber having a number average width of 2 nm or more and less than 1000 nm and an aspect ratio of 50 or more, or a cellulose nanocrystal having a number average width of 2 nm or more and less than 1000 nm and an aspect ratio of less than 50. The powdery liquid according to 1. The powdery liquid according to claim 2, wherein the cellulose nanofibers are anion-modified. The powdery liquid according to claim 3, wherein the cellulose nanofibers are anion-modified by the introduction of a carboxy group. The powdery liquid according to any one of claims 1 to 4, wherein the hydrophobic fine particles have a wetting time of 100 seconds or more according to the following test method.
Test method: After adding 10.0 g of pure water to a 30 ml glass vial at 25 ° C, take 0.1 g of hydrophobic fine particles and gently add to the top of the pure water, and all the hydrophobic fine particles will sink into the water and be placed on the top. The time until the floating hydrophobic fine particles disappear is measured as the wetting time.