JP6724289B2 - Viscosity modifier - Google Patents

Description

The present invention relates to a viscosity modifier containing carboxymethyl cellulose or a salt thereof.

Small and lightweight lithium-ion batteries (Lib) are installed in a wide range of electronic devices and electric devices such as mobile phones, laptop computers, digital cameras, digital videos, and portable music players. BACKGROUND ART Lithium-ion batteries are being put to practical use as power sources for transportation such as automobiles called eco-cars, and are being actively studied as power storage devices for leveling electric power and smart grids.
The positive electrode and the negative electrode of the lithium-ion battery each have a structure in which a current collector is sandwiched by a pair of electrode layers containing an active material and a binder. The positive electrode is manufactured by applying and drying a mixture (solution) of an active material such as lithium cobalt oxide and a binder on both surfaces of a current collector such as an aluminum foil. The negative electrode is manufactured by applying and drying a mixture (solution) of an active material such as a carbon material and a binder on a current collector such as a copper foil.

The lithium-ion battery has a positive electrode, a negative electrode, and a porous insulating film to which ions can move, and has a structure in which the positive electrode, the insulating film, and the negative electrode are laminated in multiple layers. For manufacturing a lithium-ion battery, for example, a multilayer body having a separator such as an insulating film between a positive electrode and a negative electrode is wound so that each electrode is in a Baumkuchen shape (concentric shape), and is inserted into a container to form both electrodes. Can be welded, an electrolytic solution can be injected, and the container can be sealed to obtain a lithium ion battery. When the lithium-ion battery has a cylindrical shape, the electrode multilayer body is rolled into a cylindrical shape according to the shape of the can. When the lithium-ion battery has a rectangular shape, the electrode multilayer body is wound into a flat shape according to the shape of the can.

Polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene latex (SBR), carboxymethyl cellulose, or a salt thereof is used as the binder that constitutes the electrode of the lithium ion battery, and SBR and carboxymethyl cellulose or the salt thereof is used as the aqueous binder of the negative electrode. It is commonly used in complex systems of its salts. Carboxymethyl cellulose or a salt thereof that can be used as a binder for both the positive electrode and the negative electrode also plays a role as a viscosity modifier.

Usually, this carboxymethyl cellulose or a salt thereof may be stored in a powder state, but the viscosity of an aqueous solution of a cellulosic polymer stored for a long period of time is much lower than the viscosity of a solution of a cellulosic polymer before storage. Therefore, there is a problem that it cannot serve as a viscosity modifier. On the other hand, a method of adding a polyhydric alcohol to a cellulose-based polymer aqueous solution (Patent Document 1) and a method of adding ethanol and an edetate to a cellulose-based polymer (Patent Document 2) are disclosed.

JP, 11-71478, A JP 61-186306 A

However, the technique disclosed in Patent Document 1 or Patent Document 2 is a method for preventing a decrease in the viscosity of an aqueous solution of a cellulosic polymer, and the quality of the powdery cellulosic polymer (in particular, carboxymethylcellulose or a salt thereof) is improved. It did not prevent change.

Therefore, the present invention, a change in quality when the viscosity modifier containing carboxymethylcellulose or a salt thereof is stored in a powder state, specifically, a small change in the viscosity of the aqueous solution before and after storage contains carboxymethylcellulose or a salt thereof. It is an object of the present invention to provide a viscosity modifier that

The above problems can be solved by means including the following [1] to [4].
[1] A viscosity modifier containing carboxymethyl cellulose or a salt thereof, wherein the anion-modified cellulose nanofibers are contained in an amount of 30 to 2000 mass% with respect to carboxymethyl cellulose or a salt thereof. ..
[2] The anion-modified cellulose nanofiber is a carboxylated cellulose nanofiber having an amount of carboxyl groups of 0.6 mmol/g to 2.0 mmol/g based on the absolute dry mass of the anion-modified cellulose nanofiber. The viscosity modifier according to [1], characterized in that
[3] The anion-modified cellulose nanofibers are carboxymethylated cellulose nanofibers having a degree of carboxymethyl substitution per glucose unit of the anion-modified cellulose nanofibers of 0.01 to 0.50 [1] ] Viscosity modifier described in.
[4] A composition for a lithium ion battery electrode, containing the viscosity modifier according to any one of [1] to [3].

According to the present invention, a change in quality when a viscosity modifier containing carboxymethyl cellulose or a salt thereof is stored in a powder state, specifically, a small change in viscosity of an aqueous solution before and after storage containing carboxymethyl cellulose or a salt thereof. A viscosity adjusting agent can be provided.

The viscosity modifier of the present invention has 30 anion-modified cellulose nanofibers (hereinafter, sometimes referred to as “anion-modified CNF”) to carboxymethylcellulose or a salt thereof (hereinafter sometimes referred to as “CMC”). It is characterized in that it is contained in an amount of up to 2000% by mass, and a change in quality when stored in a powder state, specifically, a change in viscosity of an aqueous solution before and after storage is greatly suppressed.

The reason why the viscosity modifier of the present invention exhibits excellent effects is not clear, but the present inventors presume as follows. By coexisting CMC and anion-modified CNF, the high charge density part of CMC is covered by the low charge density part of the anion-modified CNF surface, and external factors (heat, oxygen) It is presumed that it became difficult to be affected by (for example). In the present invention, the powder state means a viscosity modifier dried to have a water content of 12% by mass or less.

<Carboxymethyl cellulose>
Carboxymethyl cellulose used in the present invention or a salt thereof) has a structure in which a hydroxyl group in a glucose residue constituting cellulose is replaced with a carboxymethyl ether group. Carboxymethyl cellulose may be in the form of a salt. Examples of the carboxymethyl cellulose salt include metal salts such as carboxymethyl cellulose sodium salt. In the present invention, cellulose means a polysaccharide having a structure in which D-glucopyranose (also simply referred to as “glucose residue” or “anhydroglucose”) is linked by β,1-4 bonds. Cellulose is generally classified into natural cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose excluding non-crystalline regions, etc. according to the origin, production method and the like.

Examples of natural cellulose include bleached or unbleached pulp, refined linter, and cellulose produced by microorganisms such as acetic acid bacteria. The raw material of the bleached or unbleached pulp is not particularly limited, and examples thereof include wood, cotton, straw, and bamboo. The method for producing bleached or unbleached pulp is not particularly limited, and a mechanical method, a chemical method, or a method in which a mechanical method and a chemical method are combined is exemplified. Examples of the bleached or unbleached pulp include mechanical pulp, chemical pulp, groundwood pulp, sulfite pulp, kraft pulp, and papermaking pulp. Examples of the bleached or unbleached pulp also include dissolved pulp which is a main raw material for artificial fibers, cellophane, etc., which is chemically refined and mainly dissolved in chemicals for use.

Examples of the regenerated cellulose include regenerated cellulose obtained by dissolving cellulose in a solvent such as a copper ammonia solution, a cellulose xanthate solution, and a morpholine derivative and spinning it again.

As the fine cellulose, natural cellulose, cellulose-based materials such as regenerated cellulose, fine cellulose obtained by depolymerization treatment by acid hydrolysis, alkali hydrolysis, enzymatic decomposition, explosion treatment, vibration ball mill treatment, etc., cellulosic materials Fine cellulose obtained by mechanical treatment is exemplified.

In manufacturing the CMC used in the present invention, a known CMC manufacturing method can be applied. For example, CMC can be produced by treating cellulose with a mercerizing agent (alkali) to prepare mercerized cellulose (alkali cellulose), and then adding an etherifying agent to the mercerized cellulose to cause an etherification reaction. ..

As the raw material cellulose, any of the above-mentioned celluloses can be used without particular limitation, but one having a high cellulose purity is preferable, and dissolving pulp or linter is more preferable. By using these, highly pure CMC can be obtained.

Examples of the mercerizing agent include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Examples of the etherifying agent include monochloroacetic acid and sodium monochloroacetate.

In the general production method of water-soluble carboxymethyl cellulose, the molar ratio of the mercerizing agent and the etherifying agent (mercerizing agent/etherifying agent) is 2.00 to 2.0 when monochloroacetic acid is used as the etherifying agent. 45 is common. The reason is that when it is 2.00 or more, the etherification reaction can be sufficiently performed, and it can be prevented that unreacted monochloroacetic acid remains and is wasted. When it is 2.45 or less, it is possible to prevent the side reaction due to the excess mercerizing agent and monochloroacetic acid from proceeding to form the alkali metal glycolate, which is economical.

In the present invention, CMC may be a commercially available product. Examples of commercially available products include "Sunrose" manufactured by Nippon Paper Chemicals Co., Ltd.

In the present invention, the degree of etherification of CMC refers to the ratio of the groups substituted with the carboxymethyl ether group (-OCH2COOH) among the hydroxyl groups (-OH) in the glucose residue constituting cellulose.

CMC used in the present invention preferably has a carboxymethyl group substitution degree (hereinafter abbreviated as CM-DS) per glucose residue in the range of 0.55 to 1.2. When CM-DS is 0.5 or more, the solubility in water can be favorably maintained and the generation of undissolved substances can be suppressed. Further, when the CM-DS is 1.2 or less, the increase in the spinnability of the liquid can be suppressed and the handling can be easily maintained. CM-DS can be calculated by the method shown in the examples. The B-type viscosity of the CMC 1% aqueous solution at 20°C is preferably 100 to 15,000 mPa·s.

The CMC contained in the viscosity modifier of the present invention may be one kind, or may be a combination of two or more kinds of CMC having different degrees of etherification, CM-DS, B-type viscosity, molecular weight and the like.

<Anion-modified cellulose nanofiber>
In the present invention, the anion-modified cellulose nanofiber (anion-modified CNF) is a fine fiber having a fiber width of about 4 to 500 nm and an aspect ratio of 100 or more, and is carboxylated cellulose (also referred to as oxidized cellulose) or carboxymethylated. It can be obtained by defibrating anion-modified cellulose such as cellulose or cellulose having a phosphate ester group introduced therein.

(Cellulose raw material)
Examples of the cellulose raw material for producing anion-modified cellulose include plant materials (for example, wood, bamboo, hemp, jute, kenaf, agricultural land waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleaching). Kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP) thermomechanical pulp (TMP), recycled pulp , Waste paper, etc.), animal materials (for example, ascidians), algae, microorganisms (for example, acetic acid bacteria (acetobacter)), products derived from microorganisms, and the like, and any of them can be used. Is a plant- or microorganism-derived cellulose fiber, more preferably a plant-derived cellulose fiber.

(Carboxymethylation)
In the present invention, when carboxymethylated cellulose is used as the anion-modified cellulose, carboxymethylated cellulose may be obtained by carboxymethylating the above cellulose raw material by a known method, or a commercially available product is used. May be. In any case, it is preferable that the degree of carboxymethyl group substitution per anhydroglucose unit of cellulose is 0.01 to 0.50. The following method can be mentioned as an example of the method for producing such carboxymethylated cellulose. Cellulose is used as a bottoming raw material, and 3 to 20 times by mass of water and/or a lower alcohol as a solvent, specifically, water, methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary A single medium such as butanol or a mixture of two or more types is used. When the lower alcohol is mixed, the mixing ratio of the lower alcohol is 60 to 95% by mass. As the mercerizing agent, 0.5 to 20 times mol of alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide, is used per anhydrous glucose residue of the bottoming raw material. The bottoming raw material, the solvent, and the mercerizing agent are mixed, and the mercerization treatment is performed at a reaction temperature of 0 to 70° C., preferably 10 to 60° C., and a reaction time of 15 minutes to 8 hours, preferably 30 minutes to 7 hours. Thereafter, a carboxymethylating agent is added in an amount of 0.05 to 10.0 times mol per glucose residue, a reaction temperature of 30 to 90°C, preferably 40 to 80°C, and a reaction time of 30 minutes to 10 hours, preferably 1 hour. Perform the etherification reaction for ~4 hours.

In the present specification, “carboxymethylated cellulose”, which is a kind of anion-modified cellulose used for the preparation of anion-modified CNF, is one in which at least a part of the fibrous shape is maintained even when dispersed in water. Say. Therefore, it is distinguished from carboxymethyl cellulose, which is a kind of water-soluble polymer described later. When an aqueous dispersion of "carboxymethylated cellulose" is observed with an electron microscope, fibrous substances can be observed. On the other hand, no fibrous substance is observed even when an aqueous dispersion of carboxymethyl cellulose, which is a kind of water-soluble polymer, is observed. Further, in the case of "carboxymethylated cellulose", the peak of cellulose type I crystal can be observed when measured by X-ray diffraction, but no cellulose type I crystal is found in the water-soluble polymer carboxymethylcellulose.

(Carboxylated)
In the present invention, when carboxylated (oxidized) cellulose is used as the anion-modified cellulose, carboxylated cellulose (also referred to as oxidized cellulose) can be obtained by carboxylating (oxidizing) the above cellulose raw material by a known method. it can. Although not particularly limited, at the time of carboxylation, the amount of carboxyl groups should be adjusted to 0.6 to 2.0 mmol/g with respect to the absolute dry mass of the anion-modified cellulose nanofibers. Is preferable, and it is more preferable to adjust to 1.0 mmol/g to 2.0 mmol/g.

As an example of a carboxylation (oxidation) method, a cellulose raw material is oxidized in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromide, iodide or a mixture thereof. A method can be mentioned. By this oxidation reaction, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized, and the cellulose fiber having an aldehyde group and a carboxyl group (-COOH) or a carboxylate group (-COO-) on the surface. Can be obtained. The concentration of cellulose during the reaction is not particularly limited, but is preferably 5% by mass or less.

The N-oxyl compound means a compound capable of generating a nitroxy radical. As the N-oxyl compound, any compound can be used as long as it is a compound that promotes the desired oxidation reaction. Examples thereof include 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and its derivatives (for example, 4-hydroxy TEMPO).

The amount of the N-oxyl compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing cellulose as a raw material. For example, 0.01 to 10 mmol is preferable, 0.01 to 1 mmol is more preferable, and 0.05 to 0.5 mmol is still more preferable, relative to 1 g of absolutely dried cellulose. Moreover, about 0.1 to 4 mmol/L is preferable for the reaction system.

Bromides are compounds containing bromine, examples of which include alkali metal bromides that can dissociate and ionize in water. Further, iodide is a compound containing iodine, and examples thereof include alkali metal iodide. The amount of bromide or iodide used can be selected within a range that can accelerate the oxidation reaction. The total amount of bromide and iodide is, for example, preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, still more preferably 0.5 to 5 mmol, per 1 g of absolutely dried cellulose.

As the oxidizing agent, known ones can be used, and for example, halogen, hypohalous acid, halogenous acid, perhalogenic acid or salts thereof, halogen oxides, peroxides and the like can be used. Of these, sodium hypochlorite, which is inexpensive and has a low environmental load, is preferable. The appropriate amount of the oxidant used is, for example, preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, still more preferably 1 to 25 mmol, and most preferably 3 to 10 mmol per 1 g of absolutely dried cellulose. .. Further, for example, 1 to 40 mol is preferable with respect to 1 mol of the N-oxyl compound.

In the cellulose oxidation step, the reaction can proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4 to 40°C, and may be room temperature of about 15 to 30°C. Since a carboxyl group is generated in the cellulose as the reaction progresses, the pH of the reaction solution is lowered. In order to allow the oxidation reaction to proceed efficiently, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution at 8 to 12, preferably about 10 to 11. Water is preferable as the reaction medium because it is easy to handle and side reactions are unlikely to occur.

The reaction time in the oxidation reaction can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 to 6 hours, for example, 0.5 to 4 hours.

Further, the oxidation reaction may be carried out in two steps. For example, by oxidizing the oxidized cellulose obtained by filtering after the completion of the reaction in the first step again under the same or different reaction conditions, the reaction efficiency due to the salt produced as a by-product in the reaction in the first step is not increased, and the efficiency is improved. Can be well oxidized.

As another example of the carboxylation (oxidation) method, there may be mentioned a method in which a gas containing ozone and a cellulose raw material are brought into contact with each other to be oxidized. By this oxidation reaction, at least the 2- and 6-position hydroxyl groups of the glucopyranose ring are oxidized and the cellulose chain is decomposed. The ozone concentration in the gas containing ozone is preferably 50 to 250 g/m3, and more preferably 50 to 220 g/m3. The amount of ozone added to the cellulose raw material is preferably 0.1 to 30 parts by mass, and more preferably 5 to 30 parts by mass when the solid content of the cellulose raw material is 100 parts by mass. The ozone treatment temperature is preferably 0 to 50°C, more preferably 20 to 50°C. The ozone treatment time is not particularly limited, but is about 1 to 360 minutes, preferably about 30 to 360 minutes. When the conditions of the ozone treatment are within these ranges, the cellulose can be prevented from being excessively oxidized and decomposed, and the yield of the oxidized cellulose will be good. After performing the ozone treatment, an additional oxidizing treatment may be performed using an oxidizing agent. The oxidizing agent used in the additional oxidation treatment is not particularly limited, but examples thereof include chlorine-based compounds such as chlorine dioxide and sodium chlorite, and oxygen, hydrogen peroxide, persulfuric acid, peracetic acid and the like. For example, an additional oxidization treatment can be performed by dissolving these oxidizing agents in water or a polar organic solvent such as alcohol to prepare an oxidizing agent solution, and immersing the cellulose raw material in the solution.

The amount of carboxyl groups in the oxidized cellulose can be adjusted by controlling the reaction conditions such as the addition amount of the above-mentioned oxidizing agent and the reaction time.

(Defibration)
The apparatus used for defibrating the anion-modified cellulose is not particularly limited, but a high-speed rotation type, colloid mill type, high pressure type, roll mill type, ultrasonic type, or the like device can be used. At the time of defibration, it is preferable to apply a strong shearing force to the anion-modified cellulose aqueous dispersion. In particular, in order to efficiently defibrate, it is preferable to use a wet high-pressure or ultra-high-pressure homogenizer that can apply a pressure of 50 MPa or more and a strong shearing force to the water dispersion. The pressure is more preferably 100 MPa or more, further preferably 140 MPa or more. In addition, prior to the defibration and dispersion treatment with a high-pressure homogenizer, if necessary, a known treatment such as a high-speed shear mixer, stirring, emulsification, even if subjected to a preliminary treatment to the aqueous dispersion, using a dispersing device Good.

<Method for producing viscosity modifier>
The viscosity modifier of the present invention can be obtained by drying an aqueous suspension containing CMC and anion-modified CNF. At this time, when the pH is adjusted to 9 to 11 and then dried, the generation of aggregates can be suppressed when the powdery viscosity modifier is dissolved or redispersed.

As the drying method, known methods can be used, and examples thereof include spray drying, squeezing, air drying, hot air drying, and vacuum drying. The drying device is not particularly limited, but it is a continuous tunnel drying device, band drying device, vertical drying device, vertical turbo drying device, multi-stage disc drying device, aeration drying device, rotary drying device, airflow drying device, sprayer. Dryer dryer, spray dryer, cylinder dryer, drum dryer, belt dryer, screw conveyor dryer, rotary dryer with heating tube, vibration transport dryer, batch-type box dryer, aeration dryer, vacuum The box type drying device, the stirring drying device and the like can be used alone or in combination of two or more.

Among these, the use of an apparatus for forming a thin film and drying can directly supply heat energy to the object to be dried uniformly, and the drying process can be performed more efficiently and in a short time, so that energy efficiency can be improved. It is preferable from the point. Further, an apparatus for forming a thin film and drying it is preferable because the dried product can be immediately recovered by a simple means such as scraping the thin film. Furthermore, when a thin film is formed and then dried, the generation of aggregates can be suppressed when the powdery viscosity adjusting agent is dissolved or redispersed. As an apparatus for forming a thin film and drying it, for example, a drum drying apparatus or a belt drying apparatus for forming a thin film on a drum or belt with a blade, a die or the like and drying it.

The thickness of the thin film to be dried is preferably 50 to 1000 μm, more preferably 100 to 300 μm. When it is 50 μm or more, scraping after drying is easy, and when it is 1000 μm or less, the effect of further improving redispersibility is observed.

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

<Production of carboxylated (TEMPO-oxidized) CNF>
Bleached unbeaten kraft pulp from softwood (whiteness 85%) 500 g (absolute dryness) was added to 780 mg of TEMPO (Sigma Aldrich) and 500 ml of an aqueous solution in which sodium bromide 75.5 g was dissolved, until the pulp was uniformly dispersed. It was stirred. An aqueous sodium hypochlorite solution was added to the reaction system at 6.0 mmol/g to start the oxidation reaction. Although the pH in the system was lowered during the reaction, the pH was adjusted to 10 by sequentially adding a 3M sodium hydroxide aqueous solution. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system stopped changing. The mixture after the reaction was filtered with a glass filter to separate pulp, and the pulp was sufficiently washed with water to obtain oxidized pulp (carboxylated cellulose). The pulp yield at this time was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.6 mmol/g.

The oxidized pulp obtained in the above step was adjusted to 1.0% (w/v) with water and treated with an ultrahigh pressure homogenizer (20° C., 150 Mpa) three times to obtain an anion-modified cellulose nanofiber dispersion liquid. It was The obtained fiber had an average fiber diameter of 40 nm and an aspect ratio of 150.

<Method for measuring the amount of carboxyl groups>
60 ml of a 0.5% by mass slurry of carboxylated cellulose (aqueous dispersion) was prepared and adjusted to pH 2.5 by adding a 0.1 M hydrochloric acid aqueous solution, and then a 0.05 N sodium hydroxide aqueous solution was added dropwise to adjust the pH to 11 The electric conductivity was measured until it became, and it was calculated from the amount (a) of sodium hydroxide consumed in the neutralization step of the weak acid with a gradual change in electric conductivity using the following formula:
Amount of carboxyl group [mmol/g carboxylated cellulose]=a [ml]×0.05/mass of carboxylated cellulose [g].

<Production of carboxymethyl (CM)-modified CNF>
To a stirrer with which pulp can be mixed, pulp (NBKP (softwood bleached kraft pulp), manufactured by Nippon Paper Industries) is added in a dry mass of 200 g, and sodium hydroxide is added in a dry mass of 111 g to give a pulp solid content of 20% (w/v ) Was added. Then, after stirring for 30 minutes at 30° C., 216 g (as active ingredient conversion) of sodium monochloroacetate was added. After stirring for 30 minutes, the temperature was raised to 70° C. and the mixture was stirred for 1 hour. Then, the reaction product was taken out, neutralized and washed to obtain a carboxymethylated pulp having a carboxymethyl substitution degree of 0.25 per glucose unit. Then, the carboxymethylated pulp was made to have a solid content of 1% with water, and treated by a high-pressure homogenizer at 20° C. and a pressure of 150 MPa five times to be defibrated to obtain carboxymethylated cellulose fibers. The obtained fiber had an average fiber diameter of 50 nm and an aspect ratio of 120.

<Measurement method of carboxymethyl substitution degree per glucose unit>
About 2.0 g of carboxymethyl cellulose fibers (extra-dried) was precisely weighed and placed in a 300 mL Erlenmeyer flask with a stopper. 100 mL of a liquid containing 100 mL of special grade concentrated nitric acid added to 1000 mL of nitric acid methanol was added and shaken for 3 hours to convert the carboxymethyl cellulose salt (CMized cellulose) into hydrogenated CM-modified cellulose. 1.5 to 2.0 g of hydrogenated CM-modified cellulose (absolutely dried) was precisely weighed and placed in a 300 mL Erlenmeyer flask with a stopper. The hydrogenated CM cellulose was wetted with 15 mL of 80% methanol, 100 mL of 0.1 N NaOH was added, and the mixture was shaken at room temperature for 3 hours. Excess NaOH was back titrated with 0.1 N H ₂ SO ₄ using phenolphthalein as an indicator. The degree of carboxymethyl substitution (DS) was calculated by the following formula:
A=[(100×F′−(0.1N H ₂ SO ₄ )(mL)×F)×0.1]/(absolute dry mass (g) of hydrogenated CM cellulose)
DS=0.162×A/(1-0.058×A)
A: 1N NaOH amount (mL) required to neutralize 1 g of hydrogenated CM cellulose
F': 0.1 N H ₂ SO ₄ factor F: 0.1 N NaOH factor.

<Measurement method of average fiber diameter and aspect ratio>
The average fiber diameter and average fiber length of the anion-modified CNF were analyzed for 200 randomly selected fibers using a field emission scanning electron microscope (FE-SEM). The aspect ratio was calculated by the following formula:
Aspect ratio = average fiber length/average fiber diameter.

(Example 1)
As the anion-modified CNF, the above carboxylated CNF (amount of carboxyl group: 1.6 mmol/g, average fiber diameter: 40 nm, aspect ratio: 150) was used. To 100 parts by mass (solid content) of carboxymethyl cellulose (trade name: MAC800LC, manufactured by Nippon Paper Industries, viscosity (1%, 25° C.) about 8000 mPa·s, carboxymethyl substitution degree about 0.7) and anion-modified CNF 0.7 mass% aqueous suspension of 333 mass% (solid content) was mixed, and the mixture was stirred for 60 minutes with a TK homomixer (12,000 rpm) to obtain an aqueous solution of a viscosity modifier (aqueous dispersion liquid). ) Was prepared. The pH of this aqueous solution was about 7-8. To this aqueous solution, 0.5% aqueous sodium hydroxide solution was added to adjust the pH to 9, and then applied to the drum surface of a drum dryer D0405 (manufactured by Katsuragi Industry Co., Ltd.) to form a thin film having a thickness of about 100 to 200 μm. And the vapor pressure is 0.5 MPa. G was dried at a drum rotation speed of 2 rpm to obtain a dried solid substance of a viscosity modifier having a water content of 5% by mass.

Next, the dried solid matter of the viscosity modifier obtained above was stored in a 60° C. drier, the viscosity after 10, 25 days was measured, and the rate of change in viscosity from before the 60° C. drier storage was investigated.
Viscosity change rate=[(viscosity 2-viscosity 1)/viscosity 1]×100 (%)
1% aqueous solution viscosity (viscosity 1) of the viscosity modifier for 0 days (before packaging), 1% aqueous solution viscosity (viscosity 2) of the viscosity modifier after storage for 10 or 25 days at 60° C. after packaging ) Change rate of viscosity

In addition, the viscosity was measured by adding water to the dry solid obtained above so as to form a 1% by mass aqueous suspension, stirring the mixture for 60 minutes using a TK homomixer (12,000 rpm), and adjusting the viscosity. An aqueous solution of After adjusting the obtained aqueous solution to 25° C.±0.2° C., the B-type viscosity (rotation speed 30 rpm, 3 minutes) was measured. The results are shown in Table 1.

(Comparative Example 1)
Carboxymethyl cellulose (trade name: MAC800LC) was stored in a dryer at 60° C., viscosity after 10, 25 days was measured, and the rate of change in viscosity from before storage at 60° C. was investigated.

For the viscosity measurement, water was added to MAC800LC so as to be a 1% mass solution, and the mixture was stirred for 3 hours using a dissolution stirrer (600 rpm) to obtain an aqueous solution of a viscosity modifier (CMC alone). The obtained solution was adjusted to 25° C.±0.2° C., and then the B-type viscosity (rotation speed 30 rpm, 3 minutes) was measured. The results are shown in Table 1.

Claims (2)

A carboxymethylcellulose or viscosity modifier powder state a salt thereof, with respect carboxymethylcellulose or a salt thereof, flour carboxymethyl cellulose nanofibers characterized by containing 30 to 2000 mass% Viscosity modifier for body condition. The carboxymethyl cellulose nanofibers according to claim 1, wherein the carboxymethyl degree of substitution per glucose unit of carboxymethyl cellulose nanofibers are carboxymethylated cellulose nanofibers is 0.01 to 0.50 The viscosity modifier in powder form according to item 1.