WO2021019896A1

WO2021019896A1 - Carboxymethyl cellulose or salt thereof, and composition thereof

Info

Publication number: WO2021019896A1
Application number: PCT/JP2020/021609
Authority: WO
Inventors: 邦朗土井; 真也小野
Original assignee: ダイセルファインケム株式会社
Priority date: 2019-07-29
Filing date: 2020-06-01
Publication date: 2021-02-04
Also published as: TW202118794A; KR20220042057A; CN113993904B; CN113993904A; JP2021021018A; JP7481812B2

Abstract

Carboxymethyl cellulose or a salt thereof is adjusted to a form such that D10 is 90 μm or higher, D50 is 120-470 μm, and D90 is 500 μm or lower, where D10, D50, and D90 are, respectively, the 10% cumulative, 50% cumulative, and 90% cumulative grain sizes from the small-grain-size side in the volume-based cumulative grain size distribution. D10 may be about 100 μm or higher, D50 may be about 150-200 μm, and D90 may be about 250 μm or lower. In granular carboxymethyl cellulose or a salt thereof, the proportion of particles having a roundness of 50% or higher may be about 90 vol% or higher with respect to the whole, and the proportion of particles having a roundness of 70% or higher may be about 70 vol% with respect to the whole. The carboxymethyl cellulose or salt thereof can be dissolved efficiently in water even with gentle stirring.

Description

Carboxymethyl cellulose or its salt and its composition

In the present disclosure, carboxymethyl cellulose (hereinafter, also simply referred to as CMC) or a salt thereof, an aqueous composition containing CMC or a salt thereof and water, and CMC or a salt thereof are prepared into granules showing a predetermined particle size distribution. It relates to a method for improving solubility in water.

CMC is one of the typical water-soluble polymer materials, and is used in a wide range of applications such as foods, cosmetics, pharmaceuticals, and negative electrode materials for lithium-ion batteries. Normally, CMC is often used in the form of an aqueous solution, but when mixed with water, mamaco (aggregates or adhesive agglomerates) is likely to occur, and the penetration of water into the mamaco is hindered. It takes a lot of time to dissolve the CMC, and the productivity of the product cannot be improved. Therefore, a method for efficiently dissolving CMC in a short time is being studied.

According to Japanese Patent Publication No. 59-36941 (Patent Document 1), a predetermined amount of water-soluble salt and water are added to a CMC sodium salt having a purity of 95% or more (hereinafter, also simply referred to as CMC-Na). It is disclosed that CMC-Na obtained by granulation and sieving exhibits water-easiness dispersibility. In the examples of this document, a predetermined amount of anhydrous sodium sulfate or an aqueous solution thereof, salt, a water-soluble salt such as sodium L-glutamate, and water are added to CMC powder having a purity of 99%, granulated and sieved to obtain 20 meshes. CMC granules that have passed but not passed 80 mesh have been prepared.

Further, in Japanese Patent No. 3516358 (Patent Document 2), a solvent-water-containing slurry of CMC alkali salt is atomized by flowing down on a rotating disk under a predetermined gas atmosphere, or by spraying from a nozzle to atomize. Discloses a method of spray-drying and granulating. The obtained CMC powder has excellent solubility because 80% or more of the whole is in the range of 70 to 200 μm in diameter and the proportion of fine powder having a particle size of 20 μm or less is as small as 2.0% or less of the whole. Is described.

Special Publication No. 59-36941 Japanese Patent No. 3516358

However, in Patent Document 1, the use is limited because it may take a long time to dissolve because it contains relatively large particles that pass through 20 meshes, and the purity is lowered by the addition of a water-soluble salt which is an essential component. May be done.

In Patent Document 2, although the proportion of fine powder of 20 μm or less is small, the particles of the atomized CMC solution may become small depending on the conditions such as the pressure of spray injection, and the particle size of the obtained CMC powder may become relatively small. In addition, it may take time to dissolve, probably because the proportion of particles having a relatively small particle size is large.

In any of

Patent Documents

1 and 2, the relationship between the particle size and the dissolution rate, such as the specific median diameter (D50) of CMC-Na, is not described at all.

Therefore, an object of the present disclosure is to prepare a CMC or a salt thereof that can be efficiently dissolved in water (excellent in quick solubility) even with gentle stirring, an aqueous composition thereof, and the CMC or a salt thereof. The purpose is to provide a method for improving water solubility.

Another object of the present disclosure is a CMC or a salt thereof that is efficiently soluble in water even if the viscosity in an aqueous solution is high (or the molecular weight of the CMC or a salt thereof is large), and an aqueous composition thereof, and the CMC. Alternatively, there is to provide a method of preparing a salt thereof to improve water solubility.

Yet another object of the present disclosure is to provide a CMC or a salt thereof capable of improving the productivity of a negative electrode for a lithium ion battery, an aqueous composition thereof, and a method for preparing the CMC or a salt thereof to improve water solubility. To do.

As a result of diligent studies to achieve the above problems, the present inventors have found that carboxymethyl cellulose having a predetermined particle size distribution (or particle size distribution) or a salt thereof can be efficiently dissolved in water, and the present invention has been developed. completed.

That is, the carboxymethyl cellulose of the present disclosure or a salt thereof is granular, and in the volume-based cumulative distribution (or cumulative frequency distribution) of the particle size, the cumulative 10%, the cumulative 50%, and the cumulative 90% from the small particle size side. When the particle sizes are D10, D50 and D90, respectively, D10 is about 90 μm or more, D50 is about 120 to 470 μm, and D90 is about 500 μm or less.

The D10 may be about 100 μm or more, the D50 may be about 150 to 200 μm, and the D90 may be about 250 μm or less.

In the granular CMC or a salt thereof, the proportion of particles having a roundness of 50% or more may be about 90% by volume or more with respect to the whole, and the proportion of particles having a roundness of 70% or more is the whole. On the other hand, it may be about 70% by volume or more. Further, the proportion of particles having a roundness of 50% or more may be about 95% by volume or more with respect to the whole, and the proportion of particles having a roundness of 70% or more is about 80% by volume or more with respect to the whole. It may be.

The viscosity of the CMC or its salt in a 1% by mass aqueous solution may be about 1500 to 3000 mPa · s at a temperature of 25 ° C. The CMC or a salt thereof may be an electrode material.

The present disclosure includes an aqueous composition containing the CMC or a salt thereof and water, and a method for producing the aqueous composition by mixing the CMC or a salt thereof with water, and using the CMC or a salt thereof as described above. Also includes methods of preparing in granular form to improve solubility in water.

In the present disclosure, since CMC or a salt thereof has a predetermined particle size distribution, the formation of mamaco can be effectively suppressed, and it can be efficiently dissolved in water even with gentle stirring. Further, even if the viscosity of the aqueous solution is high (or the molecular weight of CMC or a salt thereof is large), it can be efficiently dissolved in water in a short time. Further, when the CMC or a salt thereof of the present disclosure is used for the negative electrode of a lithium ion battery, the CMC or a salt thereof dissolves efficiently, so that the step of preparing an aqueous composition (or a slurry-like composition) for forming an electrode is involved. Since the time can be shortened and the generation of mamaco, which causes product defects, can be suppressed, the productivity (or yield) of the lithium ion battery can be effectively improved.

FIG. 1 is a graph showing changes in the maximum torque achievement rate of the stirrer in measuring the dissolution time of CMC-Na obtained in Examples, Comparative Examples, and Reference Examples. FIG. 2 shows the volume-based particle size distribution of CMC-Na obtained in Examples, Comparative Examples, and Reference Examples. FIG. 3 shows the volume-based roundness distribution of CMC-Na obtained in Examples, Comparative Examples, and Reference Examples.

[CMC or its salt]
The granular CMCs or salts thereof of the present disclosure exhibit a predetermined particle size distribution. That is, D10 can be selected from a range of about 90 μm or more (for example, 95 to 250 μm), for example, 100 μm or more (for example, 105 to 200 μm), preferably 110 μm or more (for example, 115 to 150 μm), and more preferably 120 μm or more (for example, 120 to 140 μm). , Preferably about 120 to 130 μm).

Further, D50 can be selected from a range of about 120 to 470 μm (for example, 130 to 400 μm), for example, 140 to 350 μm (for example, 155 to 300 μm), preferably 145 to 250 μm (for example, 150 to 200 μm), and more preferably 160 to 190 μm (for example). For example, it may be about 165 to 185 μm, preferably 170 to 180 μm).

D90 can be selected from a range of about 500 μm or less (for example, 180 to 400 μm), for example, 450 μm or less (for example, 190 to 400 μm), preferably 350 μm or less (for example, 200 to 300 μm), and more preferably 250 μm or less (for example, 210 to 240 μm, preferably 210 to 240 μm). May be about 220 to 230 μm).

In addition, in this specification and claims, D10, D50 and D90 are volume-based particle diameters and can be measured by the method described in Examples described later.

Further, the particle size of CMC or a salt thereof preferably has a narrow distribution width and high uniformity. Therefore, for D10, D50 and D90, for example, D10 is 90 μm or more, D50 is 130 to 400 μm, and D90 is 450 μm. It may be less than or equal to; preferably D10 is 100 μm or more, D50 is 140 to 350 μm, and D90 may be 450 μm or less; more preferably D10 is 100 μm or more and D50 is 150 to 200 μm. Yes, D90 may be 250 μm or less; among them, D10 may be 110 μm or more, D50 may be 160 to 190 μm, and D90 may be 250 μm or less; particularly preferably D10 is 120 μm or more and D50. May be 165 to 185 μm and D90 may be 210 to 240 μm.

The mode diameter (most frequent diameter or most frequent particle diameter) in the particle size distribution of CMC or a salt thereof can be selected from the range of, for example, about 120 to 470 μm (for example, 130 to 400 μm), and for example, 140 to 350 μm (for example, 145 to 300 μm). ), It may be preferably about 150 to 250 μm (for example, 150 to 200 μm), and more preferably about 160 to 190 μm.

If the proportion of small particles is too large, the particles tend to aggregate with each other and the formation of mamaco may not be suppressed. If the proportion of large particles is too large, the area (surface area) that can come into contact with water decreases and the large particles It may become mamaco-like and dissolve for a long time. The CMC or salt thereof of the present disclosure is uniformed to a well-balanced particle size that can increase the contact area with water while suppressing the formation of agglomerates between particles, so that the dissolution time is significantly increased. Can be shortened.

The shape of the particles of CMC or its salt is preferably substantially spherical. When it is substantially spherical, the dissolution time can be greatly shortened probably because the balance between the suppression of particle aggregation and the increase in the contact area with water is good. Therefore, the CMC or a salt thereof of the present disclosure preferably has a large proportion of particles having a high roundness (or area circularity). It should be noted that although the particle size of CMC or its salt is usually discussed because of its powdery appearance, its roundness has not been paid attention to at all.

In CMC or a salt thereof, the proportion of particles having a roundness of 50% or more is, for example, 85% by volume or more, preferably 90% by volume or more (for example, 90 to 100% by volume), more preferably 95% by volume, based on the whole particles. It may be about% or more (for example, 95 to 100% by volume).

The proportion of particles having a roundness of 70% or more is, for example, 50% by volume or more, preferably 60% by volume or more (for example, 70 to 100% by volume), and more preferably 75% by volume or more (for example) with respect to the entire particles. It may be about 80 to 100% by volume).

Further, the proportion of the particles having a roundness of 90% or more is, for example, 5% by volume or more (for example, 10 to 100% by volume), preferably 13% by volume or more (for example, 15 to 100% by volume) with respect to the whole particles. There may be.

In the present specification and claims, "roundness" is defined as follows.

Roundness [%] = 4π × A / P × 100
(In the equation, π indicates the pi, A indicates the area of the particle (projected area), and P indicates the peripheral length of the particle.)

Further, in the present specification and claims, the distribution of roundness is a volume-based distribution, and can be measured by the method described in Examples described later.

When the proportions of the particles having a roundness of 50% or more, 70% or more, and 90% or more are C50, C70, and C90, respectively, for example, C50 is about 90% by volume or more with respect to the entire particles, and C70 is , About 70% by volume or more with respect to the whole particle; preferably, C50 is about 95% by volume or more with respect to the whole particle, and C70 is about 80% by volume or more with respect to the whole particle. May; more preferably, C50 is about 95% by volume or more with respect to the whole particle, C70 is about 80% by volume or more with respect to the whole particle, and C90 is about 15% by volume with respect to the whole particle. It may be more than a degree. If the proportion of particles with low roundness is too large, the dissolution time may not be shortened. Even if C90 is relatively low, if the values of C70 and C50 are high, it seems that the solubility can be effectively improved.

The average degree of substitution (etherification degree or DS) of CMC or a salt thereof can be selected from the range of, for example, about 0.1 to 3 (for example, 0.3 to 2.5), and preferably 0.4 to 2 (for example, 0). .5 to 1.5), more preferably 0.6 to 1.3 (eg 0.7 to 1.2), especially 0.8 to 1.1 (eg 0.85 to 1, preferably 0.85) It may be about 0.95). If the degree of substitution is too low, the solubility or immediate solubility may decrease, and if the degree of substitution is too high, there are many water-soluble parts and mamaco is less likely to occur, but when used as an electrode material, it is hydrophobic with the active material. Since the interaction is less likely to occur, the strength of the coating film may decrease. In addition, in this specification and claims, the average degree of substitution (the degree of etherification) can be measured by the method described below.

1.000 g of sample is precisely weighed, placed in a porcelain crucible, carbonized, completely incinerated at 630 ° C, and allowed to cool at room temperature (1). Precisely add about 250 mL of ion-exchanged water and 40 mL of 0.05 mol / L sulfuric acid to the beaker (2). Put the above (1) in the above (2), cover it loosely, boil for 30 minutes, and then cool it in cold water. After cooling, 5 drops of a phenolphthalein solution is added, and neutralization titration is performed with a 0.1 mol / L sodium hydroxide aqueous solution. A blank test is performed in the same manner, and the degree of etherification is calculated by the following formula.

Degree of etherification = 162 x A ₁ / (10000-80 x A ₁ )
[In the formula, A ₁ is the consumption of 0.05 mol / L sulfuric acid (mL) consumed by the bound alkali in 1 g of the sample converted to a dry matter, and is represented by the following formula.
_{_{_{A 1 = (B 1 -S 1}}} ) × F 1 / (W 1 × (1-M 1/100)) - 0.1mol / L sodium hydroxide required alkalinity (wherein, _{B 1} is for a blank test The consumption of the aqueous solution (mL), S ₁ is the consumption of the 0.1 mol / L sodium hydroxide aqueous solution (mL) required for the actual test, W ₁ is the sample amount (g), and M ₁ is the sample amount (g). It is the dry weight loss (mass%) of the sample, and F ₁ is a factor of 0.1 mol / L sodium hydroxide aqueous solution)].

The drying weight loss was measured according to JIS P 8203: 2010 (ISO 638: 2008), "Paper, paperboard and pulp-measurement method of absolute dryness-method by dryer". Further, the alkalinity can be measured by the method described below.

Put about 250 mL of ion-exchanged water in a beaker, add 1.000 g of the precisely weighed sample little by little with stirring, dissolve, and then add 5 mL of 0.05 mol / L sulfuric acid. Loosely cover and boil for 10 minutes, then cool in cold water. After cooling, 5 drops of a phenolphthalein solution is added, and neutralization titration is performed with a 0.1 mol / L sodium hydroxide aqueous solution. A blank test is performed in the same manner, and the alkalinity is calculated by the following formula.

Alkalinity _{_{= (B 2 -S 2) ×}} F 2 / (W 2 × (1-M 2/100))
(In the formula, B ₂ is the consumption amount (mL) of the 0.1 mol / L sodium hydroxide aqueous solution required for the blank test, and S ₂ is the consumption amount of the 0.1 mol / L sodium hydroxide aqueous solution required for the actual test. (ML), W ₂ is the sample amount (g), M ₂ is the dry weight loss (mass%) of the sample, and F ₂ is the factor of the 0.1 mol / L sodium hydroxide aqueous solution).

The dry weight loss can be measured in the same manner as the method described in the section of the average degree of substitution.

Examples of the CMC salt include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, and ammonium salts. These salts may be contained alone or in combination of two or more. Of these salts, sodium salts or ammonium salts are usually used, and sodium salts are preferable. CMC or a salt thereof may be contained in combination, but usually, a salt of CMC (preferably CMC-Na) is often used alone.

The viscosity of a 1% by mass aqueous solution of CMC or a salt thereof at a temperature of 25 ° C. may be selected from a range of, for example, about 10 to 20000 mPa · s (for example, 100 to 15000 mPa · s), for example, 1000 to 1000. 10000 mPa · s (eg 1100-8000 mPa · s), preferably 1200-6000 mPa · s (eg 1300-5000 mPa · s), more preferably 1400-4000 mPa · s (eg 1500-3000 mPa · s), especially 1600-2000 mPa · s. It may be about s (for example, 1700 to 1900 mPa · s). If the viscosity is too low, it may not be usable, especially in applications such as electrode materials.

For example, when used as a negative electrode material (thickening agent, dispersion stabilizer, binder (binder or binder), etc.) of a lithium-ion battery, CMC or its salt itself becomes a resistor, so if a large amount is added, the battery Since the performance is deteriorated, a high-viscosity product is required so that a desired function (thickening effect, etc.) can be exhibited even with a small amount of addition. On the other hand, from the viewpoint of improving productivity, there is a demand for CMC or a salt thereof, which has few undissolved substances (such as mamaco) that cause product defects and can be quickly dissolved in a short time. However, the higher the viscosity in the aqueous solution, the easier it is for mamaco to occur and the longer the dissolution time. Therefore, these characteristics are in a trade-off relationship, and it is difficult to satisfy all of them. Since the CMC or its salt of the present disclosure can suppress the generation of mamaco and effectively shorten the dissolution time even if the viscosity in the aqueous solution is high, the electrode material (thickener, dispersion stabilizer and / or binder, etc.) Can be suitably used as.

In the present specification and claims, the viscosity can be measured by the method described below.

Take 100 mL of ion-exchanged water in a dissolving bottle for viscosity measurement (hereinafter referred to as "viscosity bottle"), add a separately weighed sample (2.50 x X ₃ ) g little by little so as not to form a mamaco, and use a glass rod. Lightly crush. After extensive swelling, by adding the ion exchange water correction adding water V _{3 (mL)} was calculated by the following equation, to completely dissolve with occasional stirring with a glass rod. After dissolution, defoam under reduced pressure, place the viscosity bottle in a constant temperature water tank until the liquid temperature reaches 25 ° C., stir the sample solution uniformly, and then measure at 60 rpm with a B-type viscometer.

Viscosity (mPa · s) = Scale reading x Conversion coefficient V ₃ = 2.5 x (100-X _3- M ₃ ) -100
(In the formula, V ₃ is the ion-exchanged water-corrected additional water volume (mL), X ₃ is the measured concentration (mass%), and M ₃ is the sample drying weight loss (mass%)).

The dissolution time for preparing a 0.8% by mass aqueous solution of CMC or a salt thereof is, for example, 10 minutes or less (for example, 10 seconds to 8 minutes), preferably 6 minutes or less (for example, 30) at a temperature of 25 ° C. and a stirring speed of 300 rpm. Seconds to 5 minutes), more preferably 4 minutes or less (for example, 1 to 3 minutes), particularly 3 minutes or less (for example, 1.5 to 2.5 minutes). In the present specification and claims, the dissolution time can be measured by the method described in Examples described later.

[Production method]
The method for producing CMC or a salt thereof of the present disclosure is not particularly limited. Usually, it often includes at least a granulation step of granulating CMC or a salt thereof.

(Granulation process)
As the CMC or a salt thereof used in the granulation step, a commercially available product or the like can be used, and it is usually formed in the form of fine powder and / or fibrous.

The granulation method is a conventional granulation method, for example, rolling granulation, fluidized bed granulation, stirring granulation (mixing / stirring granulation), crushing or crushing granulation (crushing / crushing granulation), compression. Methods such as granulation (compression molding), extrusion granulation, injection granulation (melt granulation), and spray drying granulation can be used. Further, the granulation method may be a dry method, but usually a wet method is often used. Of these granulation methods, stirring granulation is often used. The granulation may be carried out under normal pressure, reduced pressure or pressure.

A binder may be added to CMC or a salt thereof depending on the granulation method or the like. The binder may be an organic solvent, but is usually water (eg, pure water). For example, in agitation granulation, water (for example, pure water) as a binder may be spray-sprayed while stirring CMC or a salt thereof with a granulator (or a stirrer).

The amount of the binder (particularly water) sprayed is, for example, 10 to 1000 parts by mass (for example, 30 to 800 parts by mass), preferably 50 to 500 parts by mass (for example, 60 to 300 parts by mass) with respect to 100 parts by mass of CMC or a salt thereof. Parts), more preferably about 70 to 200 parts by mass (for example, 80 to 100 parts by mass).

(Drying process)
Granular CMC or salts thereof obtained in the granulation step are often dried in the drying step to adjust the residual amount of the binder (particularly water). The drying method may be natural drying, or may be heated and / or dried under reduced pressure. Usually, it is often heated and dried, and the heating temperature may be, for example, 50 to 200 ° C. (for example, 60 to 150 ° C.), preferably about 70 to 100 ° C. (for example, 80 to 90 ° C.).

The residual amount of the binder may be, for example, about 30% by mass or less (for example, 20% by mass or less), preferably 15% by mass or less (for example, 10% by mass) with respect to the whole granular CMC or its salt after drying. The following), more preferably about 5% by mass or less (for example, 1% by mass or less) may be adjusted.

(Crushing process)
After drying, the obtained CMC or a salt thereof may be adjusted in particle size by pulverizing in a pulverization step, if necessary. For crushing, a conventional crusher, for example, a roll crusher, a cone crusher, a cutter mill, a stamp mill, a self-made crusher, a stone mill type crusher, a dairy bowl, a raft machine, a ring mill, or the like, which can crush to several hundred μm. (Or medium crusher); Roller mill, jet mill, high-speed rotary mill (hammer mill, pin mill, etc.), container-driven crusher (ball mill, tube mill, rod mill, etc. rotary mill, vibration mill, planetary mill, etc.), medium stirring A crusher (fine crusher or ultra-fine crusher) capable of crushing to several hundred μm or less such as a mold crusher (atwriter, bead mill, etc.) can be used. These crushers can also be used alone or in combination of two or more. Of these crushers, medium crushers such as cutter mills are often used.

When a cutter mill is used, the rotation speed may be, for example, 100 to 10000 rpm (for example, 1000 to 100,000 rpm), preferably 5000 to 50000 rpm (for example, 10000 to 30000 rpm), and more preferably about 15000 to 25000 rpm.

The crushing time may be selected according to the type of the crusher and the like, and is, for example, about 10 seconds to 1 hour (for example, 30 seconds to 30 minutes), preferably about 1 to 10 minutes (for example, 1 to 3 minutes). You may.

(Classification process)
The obtained granular CMC or a salt thereof is often classified (or sieved) in a classification step to adjust the particle size (and roundness) to a desired value. The classification method is a conventional method, for example, classification using the principle of fluid dynamics [dry classification (gravity classification, inertia classification, centrifugal classification, etc.), wet classification (sedimentation classification, mechanical classification, hydraulic classification, centrifugal classification, etc.)] , Sieving, etc. These classification methods can also be used alone or in combination of two or more. Of these, they are usually classified by sieving.

When classifying by sieving, CMC or its salt is usually classified by stacking sieves on the sieve with the smallest opening among multiple sieves with different opening so that the opening becomes larger in sequence. .. The particles to be sorted by sieving pass through a sieve having a mesh size of, for example, 500 μm, preferably 400 μm, more preferably 300 μm, still more preferably 200 μm, particularly preferably about 180 μm, and the mesh size is, for example, 90 μm, preferably 90 μm. The particles may not pass through a sieve of about 100 μm.

In this way, the CMC of the present disclosure or a salt thereof can be prepared. The present disclosure also includes a method of adjusting the particle size distribution (and roundness) of CMC or a salt thereof within a predetermined range by the above method to improve the solubility in water.

[Aqueous composition and method for producing the same]
The present disclosure also includes an aqueous composition (liquid, slurry-like or paste-like composition) containing the CMC or a salt thereof and water. In the aqueous composition, the ratio of CMC or its salt to the total amount of CMC or its salt and water is, for example, 0.01 to 10% by mass (for example, 0.1 to 5% by mass), preferably 0.3 to 2% by mass. % (For example, 0.5 to 1.5% by mass), more preferably about 0.6 to 1% by mass (for example, 0.7 to 0.9% by mass).

Water is usually pure water. The pH of the aqueous composition may be acidic, but is usually neutral or alkaline (particularly neutral).

The aqueous composition may contain CMC or a salt thereof and other components different from water. For example, when CMC or a salt thereof is used as an electrode material (such as a thickener and / or a dispersion stabilizer), the aqueous composition is an active material (eg, natural graphite, artificial graphite, hard carbon, MCMB (mesophase microspheres)). ) And other carbon materials, lithium titanate, etc.), binders (styrene butadiene copolymers, etc.) and other electrode materials may be included.

The aqueous composition can be prepared by mixing the CMC or a salt thereof, the water, and if necessary, the other components. The order and method of mixing are not particularly limited, but from the viewpoint of effectively suppressing the production of mamaco, CMC or a salt thereof is added while stirring water using a stirrer or the like (particularly, slowly or little by little). It is preferable to do so.

The stirring speed (rotational speed of the stirrer or stirring blade) when adding CMC or a salt thereof to water is, for example, 10 to 2000 rpm (for example, 100 to 1500 rpm), preferably 500 to 1000 rpm (for example, 600 to 900 rpm), more preferably. May be about 650 to 850 rpm (for example, 700 to 800 rpm). Further, after the addition of CMC or a salt thereof is completed, it is usually stirred until the dissolution is completed (or the stirring torque is stable). The stirring speed after the addition is completed may be equal to or higher than the stirring speed at the time of addition, but may be stirred slowly, for example, 10 to 1000 rpm (for example, 50 to 800 rpm), preferably 100 to 500 rpm (for example, 150). It may be about 450 rpm), more preferably about 200 to 400 rpm (for example, 250 to 350 rpm). In the present disclosure, the dissolution time can be effectively shortened even with gentle stirring.

Further, the shape of the stirring blade of the stirrer is, for example, a turbine blade (for example, an edged turbine blade, a flat or inclined turbine blade (fan turbine blade, a disc turbine blade, etc.), etc.), a paddle blade (for example, a flat paddle blade, an inclined blade, etc.). Paddle wings, etc.), propeller wings, Faudler wings, anchor wings (eg, gate wings, etc.), ribbon wings (or helical ribbon wings, etc.) (eg, multi-row ribbon wings such as double ribbon wings, single ribbon wings, etc.) Be done. These stirring blades can be used alone or in combination of two or more. Of these stirring blades, ribbon blades are preferable.

It should be noted that each aspect disclosed herein can be combined with any other feature disclosed herein.

The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples.

[material]
CMC-Na: Sodium salt of carboxymethyl cellulose, "CMC Dycel product number 2200" manufactured by Dycel Finechem Co., Ltd., degree of etherification (DS) = 0.90, viscosity of 1% by mass aqueous solution (25 ° C., 60 rpm) = 1800 mPa · s.

[Evaluation method]
(Dissolution time)
Weigh 220 g of pure water in a cylindrical glass container with a diameter of 55 mm and a depth of 130 mm, adjust the temperature to 25 ° C in a constant temperature bath, and use a torque meter ("Rotary torque meter TYPE YT" manufactured by Shinto Kagaku Co., Ltd.) and a helical ribbon type. A stirrer equipped with a stirrer blade (“Three One Motor BL1200” manufactured by Shinto Kagaku Co., Ltd.) was attached to the cylindrical glass container. The helical ribbon type stirring blade has a ribbon width of 3 mm, a height of 80 mm, a width (width in the direction perpendicular to the rotation axis): 40 mm, a number of blades: single, and the number of ribbon spirals: 3 times (height direction). The shape was 80 mm and the ribbon made three turns). While stirring the pure water at 750 rpm, a 0.8 mass% amount (about 1.77 g) of the sample was slowly added over 5 to 10 seconds. Immediately after the addition, the stirring speed was changed to 300 rpm and the measurement was started, and the time required for the torque value to stabilize at a predetermined value was defined as the dissolution time. The maximum torque achievement rate was calculated as a ratio to the torque value based on the torque value stable at the predetermined value (100%).

(Particle size distribution and roundness)
Using Malvern's "morphologi G3", measure the particle size distribution and roundness distribution of the obtained sample, calculate D10, D50 and D90 from the particle size distribution, and calculate the roundness 50 from the roundness distribution. The percentages of particles of% or more, 70% or more, and 90% or more were calculated. As for the number of samples, N = 5000 arbitrary particles were statistically processed. The particle size distribution is a volume-based distribution, and the roundness distribution is a volume-based distribution.

The roundness is calculated as follows.

[Examples 1 and 2 and Reference Examples 1 to 3]
(Preparation of granulated CMC-Na)
After putting 200 g of CMC-Na into a granulator (Toshiba Co., Ltd. "Mochitsukiki AFC-283"), spray pure water with stirring using a spray atomizer (Furupla Co., Ltd. "No. 503"). The spray nozzle was squeezed to the maximum position, and the lever was pulled once every 5 seconds to spray. Pure water was added so as to be 90% by mass (180 g) with respect to the amount of CMC-Na. At 85 ° C, use a total exhaust type dryer (“SPH-301S” manufactured by ESPEC CORPORATION) at 85 ° C until the amount of pure water (water content) relative to the total amount of CMC-Na and pure water becomes 10% by mass or less. It was dried with. After drying, the obtained sample was pulverized for 2 minutes using "Force Mill" manufactured by Osaka Chemical Co., Ltd.

(Classification of granulated CMC-Na)
A sieve of 330, 166, 83, 30 and 16 mesh (JIS standard test sieve (JIS Z 8801)) was placed on the saucer in order from the sieve having the smallest opening (in the order described above). The granulated sample was added to the uppermost sieve (16-mesh sieve), the lid was closed, and the sample was vibrated with "Microshifter 300" manufactured by Dalton Co., Ltd. for 5 minutes to perform sieving. The classified CMC-Na was taken out as evaluation samples of Examples 1 and 2 and Reference Examples 1 to 3 as shown in Table 2 and evaluated.

[Comparative Example 1]
CMC-Na was evaluated without granulation and classification.

Table 1 shows the relationship between the mesh of the sieve used and the opening, and Table 2 and FIGS. 1 to 3 show the evaluation results. In Table 2, "pass" and "on" indicate that they passed or did not pass through the sieve. Therefore, for example, "30 mesh pass 83 mesh on product" of Example 1 is a 30 mesh sieve. It means that it is CMC-Na that has passed through and has not passed through the sieve of 83 mesh. In addition, "Example 1 + Example 2 (combination)" shown in FIGS. 2 to 3 is a result of mixing CMC-Na obtained in Examples 1 and 2 (that is, 30 mesh pass166 mesh on product) and measuring. Is shown.

As is clear from Table 2 and FIGS. 1 to 3, in Comparative Example 1 and Reference Example 3 containing particles that are too small as compared with Examples 1 and 2, or Reference Example 1 containing particles that are too large, mamaco is likely to occur. While it took a long time to dissolve, in Examples 1 and 2 and Reference Example 2, it was dissolved in a shorter time than in Comparative Example 1. In particular, in Examples 1 and 2, the occurrence of mamaco was not confirmed, and the dissolution time could be shortened to 1/6 or less as compared with Comparative Example 1.

Further, in Comparative Example 1 in which the dissolution time is long, the proportion of cotton-like particles is large probably because the particles are not granulated, and in Reference Example 1, the proportion of particles having a distorted shape is large, whereas the dissolution time is large. In Examples 1 and 2 in which the value was short, the proportion of particles having a high degree of roundness was higher than in the other examples.

Since the carboxymethyl cellulose of the present disclosure or a salt thereof can be efficiently dissolved even with gentle stirring, various uses such as pharmaceuticals (for example, tablets, slurries, swallows (such as syrup)), poultices, cooling sheets, etc. X-ray contrast agents, artificial tooth stabilizers, etc.), cosmetics (eg, hair care products (shampoo, conditioner, etc.), skin care products or basic cosmetics (gel, etc.), hair dyes, etc.), daily necessities (eg, dentin polish, fragrance) , Bathing agents, water melts, etc.), foods (eg, beverages, sherbets, raw or chilled noodles, sauces, etc.), electrical and electronic parts [eg, electrodes (eg, secondary batteries such as lithium-ion batteries) , Negative electrode) materials, etc.], civil engineering or building materials (for example, oil or hot spring boring, underground continuous wall / cast-in-place pile (foundation pile), mud pressure type shield method, etc. It can be used as a thickener or dispersant for sizing agents (for example, warp sizing, back sizing, etc.), culture feeds, fire-resistant bricks, and various slurries.

In particular, since the carboxymethyl cellulose of the present disclosure or a salt thereof can be dissolved in a short time even if it has a large molecular weight (or has a high viscosity in a solution state), it is an electrode for forming an electrode of a battery such as a secondary battery. Materials (or additives) [eg, thickeners, dispersants (dispersion stabilizers or stabilizers), fluidizers, binders (or binders), suspending agents, etc.], especially negative electrode materials for lithium ion batteries ( For example, it can be effectively used as a thickener, a dispersant and / or a binder).

Claims

Granular carboxymethyl cellulose or a salt thereof, in which the cumulative 10%, 50%, and 90% particle sizes from the small particle size side are D10, D50, and D90, respectively, in the volume-based cumulative distribution of the particle size. , D10 is 90 μm or more, D50 is 120 to 470 μm, and D90 is 500 μm or less. Carboxymethyl cellulose or a salt thereof.
The carboxymethyl cellulose or a salt thereof according to claim 1, wherein D10 is 100 μm or more, D50 is 150 to 200 μm, and D90 is 250 μm or less.
Claim 1 or 2 in which the proportion of particles having a roundness of 50% or more is 90% by volume or more with respect to the whole, and the proportion of particles having a roundness of 70% or more is 70% by volume or more with respect to the whole. Carboxymethyl cellulose or a salt thereof.
Claims 1 to 3 in which the proportion of particles having a roundness of 50% or more is 95% by volume or more with respect to the whole, and the proportion of particles having a roundness of 70% or more is 80% by volume or more with respect to the whole. Carboxymethyl cellulose or a salt thereof according to any one of.
The carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 4, wherein the viscosity in a 1% by mass aqueous solution is 1500 to 3000 mPa · s at a temperature of 25 ° C.
The carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 5, which is an electrode material.
An aqueous composition containing carboxymethyl cellulose or a salt thereof and water according to any one of claims 1 to 6.
The method for producing an aqueous composition according to claim 7, wherein the carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 6 is mixed with water.
A method for improving solubility in water by preparing carboxymethyl cellulose or a salt thereof in the granular form according to any one of claims 1 to 4.