TWI836096B - Carboxymethyl cellulose or its salts and their compositions - Google Patents

Abstract

The carboxymethyl cellulose or its salt of the present invention is adjusted to the following form: in the cumulative distribution of the particle size based on the volume, when the particle sizes of cumulative 10%, cumulative 50% and cumulative 90% from the small particle size side are set as D10, D50 and D90 respectively, D10 is 90 μm or more, D50 is 120-470 μm, and D90 is 500 μm or less. The above-mentioned D10 may be about 100 μm or more, D50 may be about 150-200 μm, and D90 may be about 250 μm or less. In the granular carboxymethyl cellulose or its salt, the ratio of particles with a true roundness of 50% or more can be about 90 volume % or more relative to the whole, and the ratio of particles with a true roundness of 70% or more can be about 70 volume % or more relative to the whole. The above carboxymethyl cellulose or its salt can be dissolved in water efficiently even if it is stirred slowly.

Description

Carboxymethylcellulose or its salts and their compositions

The present invention relates to a carboxymethylcellulose (hereinafter, also referred to as CMC for short) or a salt thereof, an aqueous composition containing CMC or a salt thereof and water, and the preparation of CMC or a salt thereof into granules showing a specific particle size distribution. To improve the solubility in water.

CMC is one of the representative water-soluble polymer materials and is used in a wide range of applications. In addition to being used in food, cosmetics, pharmaceuticals, etc., it is also used as anode material for lithium-ion batteries. Generally speaking, CMC is mostly used in the form of aqueous solution, but when mixed with water, it is easy to produce powder lumps (aggregates or adhesive agglomerations), and the penetration of water into the inside of the powder lumps is hindered. Therefore, if powder lumps are formed, The dissolution of CMC will take a lot of time, and the productivity of the product cannot be improved. Therefore, methods to efficiently dissolve CMC in a short time are being studied.

Japanese Patent Publication No. 59-36941 (Patent Document 1) discloses adding a specific amount of water-soluble salt and water to CMC sodium salt (hereinafter, also referred to as CMC-Na) with a purity of 95% or more, followed by granulation and sieving. points, the CMC-Na thus obtained exhibits easy water dispersibility. In the examples of this document, a specific amount of anhydrous Glauber's salt or its aqueous solution, salt, sodium L-glutamate and other water-soluble salts and water were added to CMC powder with a purity of 99%, and granulated and sieved to prepare CMC particles that pass 20 mesh but fail to pass 80 mesh.

Furthermore, Japanese Patent No. 3516358 (Patent Document 2) discloses a method in which a solvent-water slurry containing a CMC alkali metal salt is flowed down onto a rotating disk in a specific gas environment. To atomize, or spray from a nozzle to atomize, thereby spray drying and granulating. Regarding the obtained CMC powder, it is reported that more than 80% of the total particle size is in the range of 70 to 200 μm, and the proportion of fine powder with a particle size of 20 μm or less is small, 2.0% or less of the total, so the solubility is excellent.

Prior art literature

Patent Literature

Patent document 1: Japanese Patent Publication No. 59-36941

Patent document 2: Japanese Patent No. 3516358

However, in Patent Document 1, since it contains relatively large particles that can pass through a 20-mesh screen, it may take time to dissolve, and the purity may be reduced due to the addition of a water-soluble salt as an essential ingredient, so there is a concern that its use may be limited.

In Patent Document 2, the ratio of fine powders below 20μm is relatively small, but there is a risk that the particle size of the obtained CMC powder will be relatively smaller due to different conditions such as the pressure of the spray spray, as the particles of the sprayed CMC solution become smaller. In addition, due to the large ratio of particles with relatively small particle sizes, there is a situation where dissolution takes time.

Furthermore, none of the documents in Patent Documents 1 to 2 describe any relationship between particle diameters such as the specific median diameter (D50) of CMC-Na and the dissolution rate.

Therefore, the purpose of the present invention is to provide a CMC or its salt that can be efficiently dissolved in water (i.e., excellent solubility) even when slowly stirred, and its aqueous composition, as well as a method for preparing the above CMC or its salt to improve water solubility.

Another object of the present invention is to provide a CMC or its salt that can be efficiently dissolved in water even if the viscosity of the aqueous solution is high (or even if the molecular weight of CMC or its salt is large), and its aqueous composition, as well as a method for preparing the above CMC or its salt to improve water solubility.

Another object of the present invention is to provide a CMC or its salt that can improve the productivity of negative electrodes for lithium-ion batteries, its aqueous composition, and a method for preparing the above-mentioned CMC or its salt to improve its water solubility.

The inventors of the present invention conducted in-depth research to achieve the above-mentioned goal, and found that carboxymethyl cellulose or its salt with a specific particle size distribution (or particle diameter distribution) can be efficiently dissolved in water, thereby completing the present invention.

That is, the carboxymethyl cellulose or its salt of the present invention is in granular form, and in the cumulative distribution of particle size based on volume (or cumulative frequency distribution), when the particle sizes of cumulative 10%, cumulative 50% and cumulative 90% from the small particle size side are set as D10, D50 and D90 respectively, D10 is about 90μm or more, D50 is about 120~470μm, and D90 is about 500μm or less.

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

In the above-mentioned granular CMC or its salt, the ratio of particles with a true roundness of 50% or more relative to the whole can be about 90 volume % or more, and the ratio of particles with a true roundness of 70% or more with respect to the whole can be 70. Volume % or more. In addition, the ratio of particles with a true roundness of 50% or more may be about 95% by volume or more relative to the whole, and the ratio of particles with a true roundness of 70% or more may be about 80% by volume or more relative to the whole.

The viscosity of the 1 mass% aqueous solution of the above CMC or its salt can be 1500~3000mPa at a temperature of 25°C. around s. The above-mentioned CMC or its salt may also be an electrode material.

The present invention includes an aqueous composition containing the above-mentioned CMC or its salt and water, and a method for preparing the above-mentioned aqueous composition by mixing the above-mentioned CMC or its salt and water, and also includes a method for preparing the above-mentioned CMC or its salt into the above-mentioned granular form to improve its solubility in water.

In the present invention, since CMC or its salt has a specific particle size distribution, it can effectively suppress the formation of powder lumps and can be efficiently dissolved in water even if it is stirred slowly. In addition, even if the viscosity of the aqueous solution is high (or even if the molecular weight of CMC or its salt is large), it can be efficiently dissolved in water in a short time. Furthermore, if the CMC or its salt of the present invention is used as a negative electrode of a lithium ion battery, the CMC or its salt will be dissolved efficiently, so the steps of preparing the electrode-forming aqueous composition (or slurry-like composition) can be shortened. It saves time and can also suppress the generation of powder lumps that cause product defects, so it can effectively improve the productivity (or yield) of lithium-ion batteries.

[Figure 1] is a graph showing the change in the maximum torque achievement rate of the agitator during the dissolution time measurement of CMC-Na obtained in the embodiment, comparative example and reference example.

[Figure 2] shows the volume-based particle size distribution of CMC-Na obtained in the Examples, Comparative Examples, and Reference Examples.

[Fig. 3] shows the distribution of the volume-based circularity of CMC-Na obtained in Examples, Comparative Examples, and Reference Examples.

[CMC or its salt]

The granular CMC or its salt of the present invention shows a specific particle size distribution. That is, D10 can be selected from a range of about 90μm or more (e.g., 95-250μm), for example, it can be 100μm or more (e.g., 105-200μm), preferably 110μm or more (e.g., 115-150μm), and further preferably 120μm or more (e.g., 120-140μm, preferably 120-130μm).

Furthermore, D50 can be selected from a range of about 120~470μm (e.g., 130~400μm), for example, 140~350μm (e.g., 155~300μm), preferably 145~250μm (e.g., 150~200μm), and further preferably about 160~190μm (e.g., 165~185μm, preferably 170~180μm).

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

Furthermore, in this specification and the scope of the patent application, D10, D50 and D90 are volume-based particle sizes, which can be measured by the method described in the embodiments described below.

Furthermore, the particle size of CMC or its salt is preferably distributed in a narrow range and has high uniformity. For example, regarding D10, D50 and D90, D10 is 90 μm or more, D50 is 130-400 μm, and D90 is 450 μm or less; preferably, D10 is 100 μm or more, D50 is 140-350 μm, and D90 is 450 μm or less; and further Preferably, D10 is 100 μm or more, D50 is 150-200 μm, and D90 is 250 μm or less; especially, D10 is 110 μm or more, D50 is 160-190 μm, and D90 is 250 μm or less; particularly preferably, D10 is 120 μm or more, D50 is 165-185 μm, and D90 is 210-240 μm.

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

If the ratio of smaller particles is too high, the particles are likely to aggregate and the formation of powder lumps may not be suppressed. If the ratio of larger particles is too high, the area (surface area) that can contact water is reduced, and the larger particles themselves may become powder lumps, which may increase the dissolution time. Since the CMC or its salt of the present invention is homogenized into a particle size with a good balance that suppresses the formation of aggregates between particles and increases the contact area with water, the dissolution time can be greatly shortened.

The shape of particles of CMC or its salt is preferably roughly spherical. If it is roughly spherical, the dissolution time can be greatly shortened because of the good balance between the suppression of particle aggregation and the increase in the contact area with water. Therefore, the CMC or its salt of the present invention preferably has a higher ratio of particles with high true roundness (or area circularity). Furthermore, since CMC or its salt usually has a powdery appearance, even if there is some discussion on the particle size, no attention is paid to the true roundness.

In CMC or its salt, the ratio of particles with a true roundness of 50% or more relative to the entire particle can be, for example, 85 volume % or more, preferably 90 volume % or more (for example, 90 to 100 volume %), and more preferably About 95% by volume or more (for example, 95~100% by volume).

In addition, the ratio of particles with a true roundness of 70% or more relative to the entire particle may be, for example, 50 volume % or more, preferably 60 volume % or more (for example, 70 to 100 volume %), and further preferably 75 volume % or more ( For example, about 80~100 volume%).

Furthermore, the ratio of particles with a true roundness of 90% or more relative to the total particles can be, for example, 5% by volume or more (e.g., 10-100% by volume), preferably 13% by volume or more (e.g., 15-100% by volume).

Furthermore, in this specification and the scope of the patent application, "roundness" is defined as follows.

True roundness [%] = 4π × A/P ² × 100

(In the formula, π represents the circumference of a circle, A represents the area of the particle (projected area), and P represents the circumference of the particle).

In addition, in this specification and the scope of the patent application, the distribution of roundness is a volume-based distribution, and can be measured by the method described in the Examples to be described later.

When the ratios of particles with roundness of 50% or more, 70% or more, and 90% or more are set as C50, C70, and C90, for example, C50 may be about 90% or more of the total particles, and C70 may be about 70% or more of the total particles; preferably, C50 may be about 95% or more of the total particles, and C70 may be about 80% or more of the total particles; and further preferably, C50 may be about 95% or more of the total particles, C70 may be about 80% or more of the total particles, and C90 may be about 15% or more of the total particles. If the ratio of particles with low roundness is too high, it may be impossible to shorten the dissolution time. Furthermore, even if C90 is relatively low, if the values of C70 and C50 are higher, it is easy to effectively improve the solubility.

The average degree of substitution (etherification degree or DS) of CMC or its salt can be selected from the range of about 0.1~3 (for example, 0.3~2.5), preferably 0.4~2 (for example, 0.5~1.5), more preferably 0.6~1.3 (for example, 0.7~1.2), and especially about 0.8~1.1 (for example, 0.85~1, preferably 0.85~0.95). If the degree of substitution is too low, there is a risk of reduced solubility or instant solubility. If the degree of substitution is too high, although the water-soluble part increases and it becomes difficult to generate powder lumps, when used as an electrode material, it becomes difficult to produce hydrophobic interaction with the active substance, so there is a risk of reduced film strength. In addition, in this specification and the scope of the patent application, the average degree of substitution (etherification degree) can be measured by the method described below.

Accurately weigh 1.000g of the sample and put it into a porcelain crucible. After carbonization, completely ashes it at 630°C and let it cool at room temperature (1). Precisely measure about 250 mL of ion-exchange water and 40 mL of 0.05 mol/L sulfuric acid and add them to the beaker (2). Add the above (1) to the above (2), cover slowly, boil for 30 minutes, and then cool in cold water. After cooling, add 5 drops of phenolphthalein solution, and perform neutralization titration with 0.1 mol/L sodium hydroxide aqueous solution. Use the same method to conduct a blank test and calculate the degree of etherification according to the following formula.

Etherification degree = 162×A ₁ /(10000-80×A ₁ )

[In the formula, A ₁ is the 0.05 mol/L sulfuric acid consumption (mL) consumed by the combined base in 1 g of the sample in terms of dry matter, and is represented by the following formula.

A ₁ =(B ₁ -S ₁ )×F ₁ /(W ₁ ×(1-M ₁ /100))-alkalinity

(Wherein, _B1 is the consumption of 0.1 mol/L sodium hydroxide aqueous solution required for the blank test (mL), _S1 is the consumption of 0.1 mol/L sodium hydroxide aqueous solution required for the actual test (mL), _W1 is the sample weight (g), _M1 is the drying loss of the sample (mass %), and _F1 is the factor of 0.1 mol/L sodium hydroxide aqueous solution)].

Furthermore, the above-mentioned drying loss is measured in accordance with JIS P 8203:2010 (ISO 638:2008), "Determination of absolute dryness of paper, paperboard and pulp - Method using a dryer". In addition, the above-mentioned alkalinity can be measured by the method described below.

Add about 250 mL of ion-exchange water into the beaker, and stir while adding 1.000 g of the accurately weighed sample a small amount at a time. After dissolving, add 5 mL of 0.05 mol/L sulfuric acid. Slowly cover and boil for 10 minutes, then cool in cold water. After cooling, add 5 drops of phenolphthalein solution, and perform neutralization titration with 0.1 mol/L sodium hydroxide aqueous solution. Use the same method to conduct a blank test and calculate the alkalinity according to the following formula.

Alkalinity = (B ₂ -S ₂ ) × F ₂ / (W ₂ × (1-M ₂ / 100))

(In the formula, B ₂ is the consumption of 0.1 mol/L sodium hydroxide aqueous solution required for the blank test (mL), S ₂ is the consumption of 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 drying loss of the sample (mass %), and F ₂ is the factor of 0.1 mol/L sodium hydroxide aqueous solution).

In addition, the said weight loss on drying can be measured similarly to the method described in the said average substitution degree.

Examples of CMC salts include alkaline metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts, and ammonium salts. These salts may be contained alone or in combination of two or more. Among these salts, sodium salts or ammonium salts are usually used, preferably sodium salts. Furthermore, CMC or its salts may be contained in combination, but usually, CMC salts are used alone (preferably CMC-Na).

The viscosity of a 1% by mass aqueous solution of CMC or its salt at a temperature of 25°C can be selected from 10 to 20000 mPa depending on the use, etc. s (for example, 100~15000mPa.s), for example, it can be 1000~10000mPa. s (for example, 1100~8000mPa.s), preferably 1200~6000mPa. s (for example, 1300~5000mPa.s), and more preferably 1400~4000mPa.s. s (for example, 1500~3000mPa.s), especially 1600~2000mPa. s (for example, 1700~1900mPa.s). If the viscosity is too low, it may become unusable for applications such as electrode materials.

For example, when used as negative electrode materials (thickening agent, dispersion stabilizer, binder (adhesive or adhesive), etc.) of lithium-ion batteries, since CMC or its salts themselves become resistors, if a large amount is added, the battery performance will decrease. Therefore, a high-viscosity product is required that can exert the required functions (thickening effect, etc.) even if the amount added is relatively small. On the other hand, from the perspective of improving productivity, CMC or its salts that have less undissolved matter (powder lumps, etc.) that causes product defects and can be quickly dissolved in a short time are required. However, the higher the viscosity of the aqueous solution, the easier it is to produce powder lumps and the longer the dissolution time becomes. Therefore, these characteristics are in a trade-off relationship, and it is difficult to satisfy all characteristics. The CMC or its salt of the present invention can effectively shorten the dissolution time by inhibiting the generation of powder lumps even when the viscosity of the aqueous solution is high, so it can be used as an electrode material (thickening agent, dispersing stabilizer and/or binding agent, etc.).

Furthermore, in this specification and the scope of the patent application, the viscosity can be measured by the method described below.

Take 100 mL of ion exchange water to a dissolving bottle for viscosity measurement (hereinafter referred to as "viscosity bottle"), add a sample (2.50×X ₃ ) g weighed separately in small amounts so that it does not become a powder lump, and crush it gently with a glass rod. After it is fully swollen, add the additional water amount V ₃ (mL) of ion exchange water corrected by the following formula, and dissolve it completely while stirring it frequently with a glass rod. After dissolution, reduce the pressure to defoam, place the viscosity bottle in a constant temperature water bath until the liquid temperature reaches 25°C, stir the sample solution evenly, and measure it with a B-type viscometer at 60 rpm.

Viscosity (mPa.s) = scale reading × conversion factor

V ₃ =2.5×(100-X ₃ -M ₃ )-100

(In the formula, V ₃ is the amount of additional water for ion-exchange water correction (mL), X ₃ is the measured concentration (mass %), and M ₃ is the sample drying loss (mass %)).

In addition, the said weight loss on drying can be measured similarly to the method described in the said average substitution degree.

The dissolution time of a 0.8 mass % aqueous solution of CMC or its salt is prepared at a temperature of 25°C and a stirring speed of 300 rpm, for example, less than 10 minutes (e.g., 10 seconds to 8 minutes), preferably less than 6 minutes (e.g., 30 seconds to 5 minutes), further preferably less than 4 minutes (e.g., 1 to 3 minutes), and especially less than 3 minutes (e.g., 1.5 to 2.5 minutes). Furthermore, in the present specification and the scope of the patent application, the dissolution time can be measured by the method described in the embodiments described below.

[Manufacturing method]

The method for producing CMC or its salt of the present invention is not particularly limited. Generally speaking, most of them at least include a granulation step of granulating CMC or its salt.

(Granulation step)

The CMC or its salt used in the granulation step can be a commercial product, etc., and is usually formed into a fine powder and/or fiber state.

The granulation method can use conventional granulation methods, such as rolling granulation, fluidized bed granulation, stirring granulation (mixing, stirring granulation), crushing or crushing granulation (crushing, crushing granulation), compression granulation (Compression molding granulation), extrusion granulation, injection granulation (melt granulation), spray drying granulation and other methods. In addition, the granulation method may be a dry method, but usually a wet method is used. Among these granulation methods, stirring granulation is often used. Furthermore, granulation can also be performed under normal pressure, reduced pressure, or increased pressure.

A binder may be added to CMC or its salt depending on the granulation method. The binder may also be an organic solvent, usually water (such as pure water). For example, in stirring granulation, CMC or its salt may be stirred in a granulator (or agitator) while water (such as pure water) as a binder is sprayed.

The spray amount of the binding agent (especially water) relative to 100 parts by mass of CMC or its salt can be, 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). parts by mass), and more preferably about 70 to 200 parts by mass (for example, 80 to 100 parts by mass).

(Drying step)

The granular CMC or its salt obtained in the granulation step is more than that in the drying step and is dried to adjust the remaining amount of the binding agent (especially water). The drying method may be natural drying, or drying by heating and/or reducing pressure. Generally speaking, heating is often performed for drying, and the heating temperature can 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 remaining amount of the binding agent can be, for example, about 30 mass% or less (for example, 20 mass% or less) relative to the entire dried granular CMC or its salt, or can be adjusted to preferably 15 mass% or less (for example, 10 mass%). below), and more preferably about 5 mass% or less (for example, 1 mass% or less).

(Crushing step)

After drying, the obtained CMC or its salt can also be pulverized in the pulverizing step to adjust the particle size as needed. The pulverization can be performed by using conventional pulverizers, such as roller crusher, cone crusher, cutter mill, pounder, autogenous pulverizer, stone mill, mortar, stone mill, ring mill, etc., which can pulverize to about several hundred μm (or medium crusher); roller mill, jet mill, high-speed rolling mill (hammer mill, pin mill, etc.), container-driven pulverizer (ball mill, tube mill, roller mill, etc., vibration mill, planetary mill, etc.), medium stirring pulverizer (grinder, bead mill, etc.), etc., which can pulverize to less than several hundred μm (micro pulverizer or ultrafine pulverizer), etc. These crushers can be used alone or in combination of two or more. Among these crushers, medium crushers such as shredders are often used.

When using a shredder, the rotation speed may be, for example, 100~1000000rpm (e.g. 1000~100000rpm), preferably 5000~50000rpm (e.g. 10000~30000rpm), and more preferably about 15000~25000rpm.

The grinding time can be selected according to the type of grinder, for example, it can be 10 seconds to 1 hour (for example, 30 seconds to 30 minutes), preferably about 1 to 10 minutes (for example, 1 to 3 minutes).

(grading steps)

The obtained granular CMC or its salt is mostly graded (or screened) in the grading step to adjust to the required particle size (and roundness). The grading methods include conventional methods, such as grading based on the principle of fluid dynamics [dry grading (gravity grading, inertial grading, centrifugal grading, etc.), wet grading (sedimentation grading, mechanical grading, hydraulic grading, centrifugal grading), etc.], screening, etc. These grading methods can also be used alone or in combination of two or more. Among these, screening is generally used for grading.

When sieving is used for classification, generally, sieves are stacked on a sieve with the smallest mesh among multiple sieves with different mesh sizes in a manner of increasing mesh sizes to classify the granulated CMC or its salt. The particles to be separated by sieving may also be particles that pass through a sieve with a mesh size of, for example, 500μm, preferably 400μm, more preferably 300μm, further preferably 200μm, and particularly preferably about 180μm, and particles that do not pass through a sieve with a mesh size of, for example, 90μm, preferably about 100μm.

In this way, the CMC or its salt of the present invention can be prepared. Furthermore, the present invention also includes a method for improving the solubility in water by adjusting the particle size distribution (and roundness) of CMC or its salt to a specific range by the above method.

[Aqueous composition and manufacturing method thereof]

The present invention also includes an aqueous composition (liquid, slurry or paste composition) containing the above-mentioned CMC or its salt and water. In the aqueous composition, the ratio of CMC or its salt to the total amount of CMC or its salt and water can be, for example, 0.01-10 mass % (e.g. 0.1-5 mass %), preferably 0.3-2 mass % (e.g. 0.5-1.5 mass %), and further preferably 0.6-1 mass % (e.g. 0.7-0.9 mass %).

Generally speaking, water is mostly pure water. Also, the pH of aqueous compositions can be acidic, but is usually neutral or alkaline (especially neutral).

The aqueous composition may also contain other ingredients other than CMC or its salt and water. For example, when CMC or its salt is used as an electrode material (thickening agent and/or dispersion stabilizer, etc.), the aqueous composition may also contain other electrode materials such as active substances (such as natural graphite, artificial graphite, hard carbon, MCMB (mesophase carbon microbeads) and other carbon materials, lithium titanate, etc.), binders (styrene butadiene copolymer, etc.).

The aqueous composition can be prepared by mixing the CMC or its salt, the water, and the other components as required. There is no particular restriction on the order or method of mixing. From the perspective of effectively inhibiting the formation of powder lumps, it is better to stir the water with a stirrer while adding CMC or its salt (especially slowly or in small amounts at a time).

When CMC or its salt is added to water, the stirring speed (rotation speed of the stirring blade or stirring blade) can be, for example, 10-2000 rpm (e.g., 100-1500 rpm), preferably 500-1000 rpm (e.g., 600-900 rpm), and more preferably 650-850 rpm (e.g., 700-800 rpm). After the addition of CMC or its salt is completed, stirring is usually performed until the solution is completely dissolved (or the stirring torque is stable). The stirring speed after the addition is completed can be equal to or higher than the stirring speed during the addition, but can also be stirred slowly, for example, it can be 10~1000rpm (for example, 50~800rpm), preferably 100~500rpm (for example, 150~450rpm), and further preferably about 200~400rpm (for example, 250~350rpm). In the present invention, even if stirring slowly, the dissolution time can be effectively shortened.

In addition, the shapes of the stirring blades of the mixer can be listed as follows: turbine blades (for example, marine propeller turbine blades, flat or tilted turbine blades (fan turbine blades, disc turbine blades, etc.), paddle blades (for example, flat paddle blades, tilted paddle blades, etc.), propeller blades, Pfaudler blades, anchor blades (for example, gate blades, etc.), belt blades (or spiral belt blades) (for example, double belt blades, multi-strip blades, single-strip blades, etc.), etc. These stirring blades can also be used alone or in combination of two or more. Among these stirring blades, belt blades are preferred.

Furthermore, various aspects disclosed in this specification can also be combined with any other features disclosed in this specification.

Example

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[Raw materials]

CMC-Na: Carboxymethylcellulose sodium salt, "CMC DAICE Product No. 2200" manufactured by Daicel FineChem Co., Ltd., degree of etherification (DS) = 0.90, 1 mass% aqueous solution viscosity (25°C, 60rpm) = 1800mPa. s.

[Evaluation method]

(dissolution time)

Measure 220g of pure water in a cylindrical glass container with a diameter of 55mm and a depth of 130mm, and adjust the temperature in a constant temperature bath. to 25°C, and set the torque measuring instrument ("Rotary Torque Meter TYPE YT" manufactured by Shinto Scientific Co., Ltd.) and the mixer with a spiral belt-type stirring blade ("Three-one" manufactured by Shinto Scientific Co., Ltd. -motor BL1200") is installed in the above-mentioned cylindrical glass container. Furthermore, the above-mentioned spiral belt type stirring wing system has a width of 3 mm, a height of 80 mm, a width (width perpendicular to the direction of the rotation axis): 40 mm, the number of wings: single, and the number of spirals of the belt: 3 times (banded in the height direction). (Wrap 3 times with 80mm). While stirring pure water at 750 rpm, slowly add 0.8% by mass (approximately 1.77g) of sample over 5 to 10 seconds. Immediately after the addition, the stirring speed was changed to 300 rpm to start measuring time, and the time it took until the torque value stabilized at a specific value was regarded as the dissolution time. In addition, the maximum torque achievement rate is calculated as a ratio to the torque value based on the above-mentioned torque value that is stable at a specific value (100%).

(Particle size distribution and roundness)

Using "morphologiG3" manufactured by Malvern Corporation, the particle size distribution and circularity distribution of the obtained sample were measured. D10, D50 and D90 were calculated based on the particle size distribution. The circularity was calculated to be 50% or more and 70% based on the circularity distribution. Each ratio of particles above and above 90%. Furthermore, the sample number is for statistical processing of N=5000 arbitrary particles. In addition, the particle size distribution is a volume-based distribution, and the roundness distribution is a volume-based distribution.

Furthermore, the true roundness is calculated as follows.

True roundness [%]=4π×A/P ² ×100

(In the formula, π represents the circumference of a circle, A represents the area of the particle (projected area), and P represents the circumference of the particle).

[Examples 1 to 2 and Reference Examples 1 to 3]

(Production of granulated CMC-Na)

After putting 200g of CMC-Na into a granulator ("Rice Cake Machine AFC-283" manufactured by Toshiba Corporation), while stirring, use a sprayer ("N0.503" manufactured by Furupla Corporation) to spray pure water by pulling the rod once every 5 seconds with the spray nozzle part in the most compressed state. In addition, pure water is added in such a manner that it becomes 90 mass% (180g) relative to the amount of CMC-Na. Using a full exhaust type dryer ("SPH-301S" manufactured by ESPEC Corporation), dry at 85℃ until the amount of pure water (moisture content) relative to the total amount of CMC-Na and pure water at 85℃ becomes less than 10 mass%. After drying, the obtained sample was crushed for 2 minutes using the "Force Mill" manufactured by OSAKA CHEMICAL Co., Ltd.

(Grading of Granulated CMC-Na)

On the receiving plate, 330, 166, 83, 30 and 16 mesh sieves (JIS standard test sieves (JIS Z 8801)) are stacked in order from the smaller mesh sieve (the order described above). The granulated sample is added to the top sieve (16 mesh sieve), covered with a lid, and vibrated for 5 minutes using "microSHIFT300" manufactured by DALTON Co., Ltd. for sieving. The classified CMC-Na is taken out as the evaluation samples of Examples 1~2 and Reference Examples 1~3 as shown in Table 2 and evaluated.

[Comparison Example 1]

CMC-Na was evaluated without granulating and classifying it.

The relationship between the mesh size and the mesh size of the sieve used is shown in Table 1, and the evaluation results are shown in Table 2 and Figures 1-3. Furthermore, in Table 2, "pass" and "on" respectively indicate passing or not passing the sieve, so for example, the "30 mesh pass83 mesh on product" of Example 1 means CMC-Na that passed the 30 mesh sieve and did not pass the 83 mesh sieve. In addition, "Example 1 + Example 2 (combination)" recorded in Figures 2-3 indicates the results obtained by mixing the CMC-Na obtained in Examples 1 and 2 (i.e., 30 mesh pass166 mesh on product) and measuring.

From Table 2 and Figures 1 to 3, it can be clearly seen that compared with Examples 1 to 2, in Comparative Example 1 and Reference Example 3 containing excessively small particles, or in Reference Example 1 containing excessively large particles, powder lumps are easily generated and Dissolution takes time, but in Examples 1 to 2 and Reference Example 2, dissolution took place in a shorter time than in Comparative Example 1. In particular, in Examples 1 to 2, no powder lumps were observed, and compared to Comparative Example 1, the dissolution time could be shortened to 1/6 or less.

In addition, in Comparative Example 1 with a longer dissolution time, the proportion of spongy materials is higher because granulation is not performed. In Reference Example 1, although granulation is performed, the proportion of deformed particles is higher. In contrast, in Examples 1-2 with a shorter dissolution time, the proportion of particles with higher roundness is higher than in other examples.

[Industrial availability]

The carboxymethyl cellulose or its salt of the present invention can be efficiently dissolved even if stirred slowly, and therefore can be used in various applications, such as pharmaceuticals (for example, tablets, laxatives, drinking medicines (syrups, etc.), compresses, etc.) , cooling patches, X-ray contrast agents, denture stabilizers, etc.), cosmetics (for example, hair care products (shampoo, conditioner, etc.), skin care products or basic cosmetics (gel, etc.), hair dyes, etc.), Daily necessities (such as dentifrice, fragrance, shower gel, hydrolyzed paper, etc.), food (such as beverages, snow cream, raw or cold noodles, sauces, etc.), electrical appliances. Electronic parts [e.g., electrode (e.g., negative electrode) materials for batteries (lithium-ion batteries and other secondary batteries, etc.)], materials for civil engineering or construction (e.g., oil or hot spring development, underground diaphragm walls, cast-in-place piles (foundation piles) , mud adjusting agent (or mud water adjusting agent) or mud adding agent, etc.), sizing agent (for example, warp sizing, back sizing, etc.), breeding feed, refractory bricks, various Thickener or dispersant for slurry, etc.

In particular, the carboxymethyl cellulose or its salt of the present invention can be dissolved in a short time even if the molecular weight is relatively large (or even if the viscosity in the solution state is high), so it can be effectively used to form secondary batteries, etc. Electrode materials (or additives) for battery electrodes [such as thickeners, dispersants (dispersion stabilizers or stabilizers), plasticizers, binders (or binders), suspending agents, etc.], especially lithium-ion batteries The negative electrode material of the cell (for example, thickening agent, dispersant and/or binding agent).

Claims (7)

A carboxymethyl cellulose or a salt thereof, which is an electrode material and is in granular form. In the cumulative distribution of particle size based on volume, when the particle sizes of cumulative 10%, cumulative 50% and cumulative 90% from the small particle size side are set as D10, D50 and D90 respectively, D10 is 90μm or more, D50 is 120-470μm, D90 is 500μm or less, the ratio of particles with a true roundness of 50% or more is 90 volume % or more relative to the whole, and the ratio of particles with a true roundness of 70% or more is 70 volume % or more relative to the whole. For example, the carboxymethyl cellulose or its salt according to claim 1, wherein D10 is 100 μm or more, D50 is 150 to 200 μm, and D90 is 250 μm or less. Carboxymethylcellulose or a salt thereof according to claim 1 or 2, wherein the ratio of particles with a true roundness of 50% or more relative to the whole is 95% by volume or more, and the ratio of particles with a true roundness of 70% or more with respect to the whole It is more than 80% by volume. For example, the carboxymethyl cellulose or its salt in claim 1 or 2, the viscosity of its 1 mass % aqueous solution is 1500~3000mPa.s at a temperature of 25°C. An aqueous composition comprising the carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 4 and water. A method for producing the aqueous composition of claim 5, comprising mixing the carboxymethyl cellulose or a salt thereof of any one of claims 1 to 4 with water. A method of improving solubility in water, which is to prepare carboxymethyl cellulose or a salt thereof into a granular form according to any one of claims 1 to 3.