CN113993904A

CN113993904A - Carboxymethyl cellulose or salt thereof and composition thereof

Info

Publication number: CN113993904A
Application number: CN202080044736.2A
Authority: CN
Inventors: 土井邦朗; 小野真也
Original assignee: Dairyu Meihua Co ltd
Current assignee: Dairyu Meihua Co ltd
Priority date: 2019-07-29
Filing date: 2020-06-01
Publication date: 2022-01-28
Anticipated expiration: 2040-06-01
Also published as: TW202118794A; KR20220042057A; CN113993904B; WO2021019896A1; JP2021021018A; JP7481812B2

Abstract

The present invention provides carboxymethyl cellulose or a salt thereof, wherein carboxymethyl cellulose or a salt thereof is adjusted to the following form: in the volume-based cumulative distribution of the particle diameters, when the particle diameters of 10% cumulative, 50% cumulative and 90% cumulative from the small particle diameter side are D10, D50 and D90, respectively, D10 is 90 μm or more, D50 is 120 to 470 μm, and D90 is 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 carboxymethyl cellulose or a salt thereof, the proportion of particles having a circularity of 50% or more may be about 90% by volume or more with respect to the whole, and the proportion of particles having a circularity of 70% or more may be about 70% by volume or more with respect to the whole. The carboxymethyl cellulose or a salt thereof can be dissolved in water with good efficiency even if slowly stirred.

Description

Carboxymethyl cellulose or salt thereof and composition thereof

Technical Field

The present invention relates to carboxymethyl cellulose (hereinafter also simply referred to as CMC) or a salt thereof, an aqueous composition containing CMC or a salt thereof and containing water, and a method for improving solubility in water by preparing CMC or a salt thereof into a granular form exhibiting a given particle size distribution.

Background

CMC is one of typical water-soluble polymer materials, and has been used in a wide range of applications such as negative electrode materials for lithium ion batteries, in addition to foods, cosmetics, pharmaceuticals, and the like. Usually, CMC is used in the form of an aqueous solution in many cases, but when it is mixed with water, lumps (aggregates or cohesive aggregates) are likely to be generated, and penetration of water into the inside of the lumps is hindered, and therefore, once the lumps are generated, dissolution of CMC takes a long time, and productivity of the product cannot be improved. Therefore, a method of dissolving CMC in a short time with good efficiency has been studied.

Japanese patent publication No. 59-36941 (patent document 1) discloses: CMC-Na obtained by adding a water-soluble salt and water in predetermined amounts to a CMC sodium salt having a purity of 95% or more (hereinafter, also simply referred to as CMC-Na), followed by granulation and sieving showed easy dispersibility in water. In the examples of this document, CMC granules that pass 20 mesh and fail to pass 80 mesh were prepared by adding predetermined amounts of thenardite or its aqueous solution, water-soluble salt such as common salt, sodium L-glutamate and the like, and water to CMC powder having a purity of 99%, granulating and sieving.

Further, japanese patent No. 3516358 (patent document 2) discloses: a method of granulating by spraying and drying a solvent-water slurry containing a CMC alkali salt by flowing down the slurry onto a rotating disk in a predetermined gas atmosphere or by spraying the slurry from a nozzle. The following are described therein: the CMC powder obtained has excellent solubility because 80% or more of the whole CMC powder is in the range of 70-200 μm in particle size and the proportion of fine powder with particle size of 20 μm or less is as low as 2.0% or less of the whole CMC powder.

Documents of the prior art

Patent document

Patent document 1: japanese examined patent publication No. 59-36941

Patent document 2: japanese patent No. 3516358

Disclosure of Invention

Problems to be solved by the invention

However, in patent document 1, there is a possibility that it takes a long time to dissolve the particles containing particles larger than 20 mesh, and that the purity is lowered by adding a water-soluble salt as an essential component, so that the use is limited.

In patent document 2, although the proportion of fine powder of 20 μm or less is small, there is a possibility that the size of the atomized CMC solution becomes small and the particle size of the obtained CMC powder also becomes small due to conditions such as the pressure of spray injection. Further, since the proportion of particles having a small particle size is large, it may take a long time to dissolve the particles.

In any of patent documents 1 to 2, there is no description about the relationship between the particle diameter such as the specific median particle diameter (D50) of CMC-Na and the dissolution rate.

Accordingly, an object of the present invention is to provide CMC or a salt thereof which can be dissolved in water with good efficiency even with slow stirring (i.e., excellent in solubility), an aqueous composition thereof, and a method for improving water solubility by producing the CMC or the salt thereof.

Another object of the present invention is to provide CMC or a salt thereof which can be dissolved in water with good efficiency even if the viscosity in an aqueous solution is high (or even if the molecular weight of CMC or a salt thereof is large), an aqueous composition thereof, and a method for improving water solubility by producing the CMC or a salt thereof.

Another object of the present invention is to provide CMC or a salt thereof, an aqueous composition thereof, and a method for improving water solubility by producing the CMC or the salt thereof, which can improve productivity of a negative electrode for a lithium ion battery.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that carboxymethyl cellulose or a salt thereof having a predetermined particle size distribution (or particle size distribution) can be dissolved in water with good efficiency, thereby completing the present invention.

That is, the carboxymethyl cellulose or a salt thereof of the present invention is in a granular form, wherein when the particle diameters of 10% accumulation, 50% accumulation and 90% accumulation from the small particle diameter side are D10, D50 and D90, respectively, in a volume-based cumulative distribution (or cumulative power distribution) of the particle diameters of the carboxymethyl cellulose or a salt thereof, D10 is about 90 μm or more, D50 is about 120 to 470 μm or less, 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 the salt thereof, the proportion of particles having a circularity of 50% or more may be 90% or more by volume based on the whole, and the proportion of particles having a circularity of 70% or more may be 70% or more by volume based on the whole. The proportion of particles having a circularity of 50% or more may be about 95% by volume or more based on the whole, and the proportion of particles having a circularity of 70% or more may be about 80% by volume or more based on the whole.

The viscosity of a 1 mass% aqueous solution of the CMC or its salt may be about 1500 to 3000 mPas at a temperature of 25 ℃. The above CMC or salt thereof may be an electrode material.

The invention also includes: an aqueous composition comprising the above-mentioned CMC or salt thereof and water; a method for producing the aqueous composition by mixing the CMC or salt thereof with water; and a method for improving the solubility in water by preparing the above CMC or a salt thereof in the above granular form.

ADVANTAGEOUS EFFECTS OF INVENTION

In the present invention, CMC or a salt thereof has a given particle size distribution, and therefore, the generation of lumps can be effectively suppressed, and the CMC or the salt thereof can be dissolved in water with good efficiency even with slow stirring. Even if the viscosity of the aqueous solution is high (or even if the molecular weight of CMC or a salt thereof is large), the aqueous solution can be dissolved in water in a short time with good efficiency. Further, if the CMC or the salt thereof of the present invention is used in a negative electrode of a lithium ion battery, the CMC or the salt thereof is dissolved with good efficiency, so that the time required for the step of preparing an aqueous composition (or a slurry-like composition) for electrode formation can be shortened, and also the generation of lumps which cause product defects can be suppressed, and therefore, the productivity (or yield) of the lithium ion battery can be effectively improved.

Drawings

Fig. 1 is a graph showing the evolution of the maximum torque achievement rate of the mixer in the measurement of the dissolution time of CMC-Na obtained in the examples, comparative examples and reference examples.

FIG. 2 shows the volume-based particle size distributions of CMC-Na obtained in examples, comparative examples and reference examples.

FIG. 3 shows the distribution of the circularity of CMC-Na on the volume basis obtained in examples, comparative examples and reference examples.

Detailed Description

[ CMC or salt thereof ]

The CMC or a salt thereof in granular form of the present invention exhibits a given particle size distribution. That is, D10 may be selected from a range of about 90 μm or more (e.g., 95 to 250 μm), and for example, may be about 100 μm or more (e.g., 105 to 200 μm), preferably about 110 μm or more (e.g., 115 to 150 μm), and more preferably about 120 μm or more (e.g., 120 to 140 μm, preferably about 120 to 130 μm).

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

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

In the present specification and claims, the volume-based particle diameters of D10, D50, and D90 can be measured by the methods described in the examples described below.

Further, since CMC or a salt thereof preferably has a narrow distribution width and high uniformity of particle size, D10, D50, and D90 may be, for example: d10 is more than 90 μm, D50 is 130-400 μm, and D90 is less than 450 μm; it may be preferable that: d10 is more than 100 μm, D50 is 140-350 μm, and D90 is less than 450 μm; it may be further preferable that: d10 is more than 100 μm, D50 is 150-200 μm, and D90 is less than 250 μm; wherein, the following can be also included: d10 is more than 110 μm, D50 is 160-190 μm, and D90 is less than 250 μm; it may be particularly preferred that: d10 is 120 μm or more, D50 is 165 to 185 μm, and D90 is 210 to 240 μm.

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

When the proportion of small particles is too large, there is a risk that the particles are likely to aggregate with each other and the formation of lumps cannot be suppressed, and when the proportion of large particles is too large, there is a risk that the area (surface area) that can be contacted with water is reduced, and the large particles themselves become lumps and the dissolution time becomes long. The CMC or the salt thereof of the present invention is homogenized to a particle size that is well balanced so as to increase the contact area with water while suppressing the formation of aggregates among particles, and therefore, the dissolution time can be significantly shortened.

The shape of the particles of CMC or a salt thereof is preferably substantially spherical. In the case of a substantially spherical shape, the balance between suppression of aggregation of particles and increase in contact area with water is good, and for this reason, the dissolution time can be significantly shortened. Therefore, it is preferable that the CMC or the salt thereof of the present invention contains a large proportion of particles having a high circularity (or area circularity). It should be noted that CMC or a salt thereof is usually powdery in appearance, and for this reason, although there is a study on the particle size, the roundness is not paid attention at all.

The proportion of particles having a circularity of 50% or more in the CMC or salt thereof may be, for example, 85% by volume or more, preferably 90% by volume or more (e.g., 90 to 100% by volume), and more preferably 95% by volume or more (e.g., 95 to 100% by volume) with respect to the entire particles.

The proportion of particles having a circularity of 70% or more may be, 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, 80 to 100% by volume) with respect to the entire particles.

The proportion of particles having a circularity of 90% or more may be, for example, 5% by volume or more (for example, 10 to 100% by volume), and preferably 13% by volume or more (for example, 15 to 100% by volume) with respect to the entire particles.

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

Roundness [% ] -4 π × A/P × 100

(wherein π represents the circumference ratio, A represents the area of the particle (projected area), and P represents the circumference of the particle.)

In the present specification and claims, the distribution of circularity is a volume-based distribution, and can be measured by the method described in the examples described below.

When the proportions of particles having a circularity of 50% or more, 70% or more, and 90% or more are C50, C70, and C90, respectively, for example: about 90% by volume or more of C50 to the whole particles, and about 70% by volume or more of C70 to the whole particles; it may be preferable that: about 95 vol% or more of C50 and about 80 vol% or more of C70 based on the whole particles; it may be further preferable that: the content of C50 is about 95 vol% or more based on the whole particle, the content of C70 is about 80 vol% or more based on the whole particle, and the content of C90 is about 15 vol% or more based on the whole particle. If the proportion of particles having a low circularity is too large, the dissolution time may not be shortened. Even when C90 is low, the solubility is easily and effectively improved when the values of C70 and C50 are high.

The average degree of substitution (degree of etherification or DS) of CMC or its salt may be selected, for example, from about 0.1 to 3 (e.g., from 0.3 to 2.5), preferably from about 0.4 to 2 (e.g., from 0.5 to 1.5), more preferably from about 0.6 to 1.3 (e.g., from 0.7 to 1.2), and particularly preferably from about 0.8 to 1.1 (e.g., from 0.85 to 1, preferably from 0.85 to 0.95). When the substitution degree is too low, the solubility or the instant solubility may be lowered, and when the substitution degree is too high, the water-soluble portion becomes large and the formation of nodules is difficult, but when the substitution degree is too high, the hydrophobic interaction with the active material is difficult to occur, and therefore, the coating film strength may be lowered. In the present specification and claims, the average degree of substitution (etherification degree) can be measured by the method described below.

1.000g of a sample was precisely weighed, placed in a magnetic crucible, carbonized, completely ashed at 630 ℃ and naturally cooled at room temperature (1). About 250mL of ion-exchanged water and 40mL (2) of 0.05mol/L sulfuric acid were precisely weighed and added to a beaker. The above (1) was added to the above (2), the lid was lightly covered, and after boiling for 30 minutes, the mixture was cooled in cold water. After cooling, 5 drops of phenolphthalein solution were added, and neutralization titration was performed using 0.1mol/L aqueous sodium hydroxide solution. A blank test was conducted in the same manner, and the etherification degree was calculated by the following formula.

Degree of etherification 162 xA₁/(10000－80×A₁)

[ in the formula, A₁The consumption (mL) of sulfuric acid was 0.05mol/L as a consumption of the bound base in 1g of the dried product, and the consumption was represented by the following formula.

A₁＝(B₁-S₁)×F₁/(W₁×(1－M₁Per 100)) -basicity

(in the formula, B₁Consumption (mL) of 0.1mol/L aqueous sodium hydroxide solution required for a blank test, S₁Consumption (mL) of 0.1mol/L aqueous sodium hydroxide solution required for practical test, W₁Is the sample amount (g), M₁Weight loss on drying (% by mass) of the sample F₁Factor for 0.1mol/L aqueous sodium hydroxide solution)]。

The weight loss by drying was measured in accordance with JIS P8203: 2010(ISO 638:2008) and "method for measuring absolute drying rates of paper, paperboard, and pulp — method using a dryer". The basicity can be measured by the method described below.

About 250mL of ion-exchanged water was placed in a beaker, 1.000g of a precisely weighed sample was added and dissolved in a small amount of water while stirring, and then 5mL of 0.05mol/L sulfuric acid was added. The lid was covered lightly and after boiling for 10 minutes, cooled in cold water. After cooling, 5 drops of phenolphthalein solution were added, and neutralization titration was performed using 0.1mol/L aqueous sodium hydroxide solution. A blank test was performed by the same method, and the basicity was calculated by the following formula.

Basicity ═ B₂－S₂)×F₂/(W₂×(1－M₂/100))

(in the formula, B₂Consumption (mL) of 0.1mol/L aqueous sodium hydroxide solution required for a blank test, S₂Consumption (mL) of 0.1mol/L aqueous sodium hydroxide solution required for practical test, W₂As sample amounts (g), M₂Weight loss on drying (% by mass) of the sample F₂Factor of 0.1mol/L aqueous sodium hydroxide solution).

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

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

The viscosity of a 1 mass% aqueous solution of CMC or a salt thereof at 25 ℃ may be selected from a range of, for example, about 10 to 20000 mPas (for example, 100 to 15000 mPas) depending on the application, and may be, for example, about 1000 to 10000 mPas (for example, 1100 to 8000 mPas), preferably about 1200 to 6000 mPas (for example, 1300 to 5000 mPas), more preferably about 1400 to 4000 mPas (for example, 1500 to 3000 mPas), and particularly preferably about 1600 to 2000 mPas (for example, 1700 to 1900 mPas). When the viscosity is too low, there is a possibility that the composition cannot be used particularly for applications such as electrode materials.

For example, when used as a negative electrode material (a thickener, a dispersion stabilizer, a binder (a binder or a binder), or the like) of a lithium ion battery, CMC or a salt thereof itself becomes a resistance, and therefore, if added in a large amount, the battery performance is degraded, and therefore, a high-viscosity product is required that can exhibit a desired function (a thickening effect or the like) even with a small addition amount. On the other hand, from the viewpoint of improving productivity, CMC or a salt thereof is required which is less in undissolved matter (such as lumps) causing product defects and which can be rapidly dissolved in a short time. However, since the higher the viscosity of the aqueous solution, the more likely to cause lumps and the longer the dissolution time, these properties are in a trade-off relationship and it is difficult to satisfy all of them. The CMC or the salt thereof of the present invention can be suitably used as an electrode material (thickener, dispersion stabilizer, binder, or the like) because the generation of lumps can be suppressed and the dissolution time can be effectively shortened even when the viscosity in an aqueous solution is high.

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

A sample (2.50X) was accurately weighed separately into a dissolution flask for measuring viscosity (hereinafter referred to as "viscosity flask") containing 100mL of ion-exchanged water₃) g was added in small amounts and many times so as not to form lumps, and gently crushed with a glass rod. After sufficient swelling, the ion-exchanged water obtained by the following formula was added to correct the added water amount V₃(mL), the solution was dissolved completely with occasional stirring with a glass rod. After dissolution, vacuum deaeration was performed, and the viscosity bottle was placed in a constant temperature water tank until the liquid temperature reached 25 ℃, and the sample solution was uniformly stirred and then measured at 60rpm by a B-type viscometer.

Viscosity (mPas) is the scale reading multiplied by the conversion factor

V₃＝2.5×(100－X₃－M₃)－100

(in the formula, V₃Correcting the amount of added water (mL), X, for ion-exchanged water₃For determination of concentration (% by mass), M₃For drying and reducing weight of sample(mass%)).

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

[ production method ]

The method for producing the CMC or salt thereof of the present invention is not particularly limited. In general, at least a granulation step of granulating CMC or a salt thereof is often included.

(granulation Process)

The CMC or salt thereof used in the granulation step can be commercially available products and the like, and is usually formed in a fine powder state and/or a fiber state in many cases.

The granulation method may be any of conventional granulation methods, for example, rotary granulation, fluidized bed granulation, stirring granulation (mixing/stirring granulation), pulverization or crushing granulation (pulverization/crushing granulation), compression granulation (compression molding granulation), extrusion granulation, spray granulation (melt granulation), spray drying granulation, and the like. The granulation method may be a dry method, but is usually a wet method in many cases. Among these granulation methods, stirring granulation is generally used. The granulation may be performed under normal pressure, reduced pressure, or increased pressure.

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

The amount of the binder (particularly water) sprayed may be, for example, about 10 to 1000 parts by mass (for example, about 30 to 800 parts by mass), preferably about 50 to 500 parts by mass (for example, about 60 to 300 parts by mass), and more preferably about 70 to 200 parts by mass (for example, about 80 to 100 parts by mass) based on 100 parts by mass of the CMC or the salt thereof.

(drying Process)

In many cases, the granular CMC or salt thereof obtained in the granulation step is dried in the drying step to adjust the remaining amount of the binder (particularly, water). The drying method may be natural drying, or drying by heating and/or reduced pressure. Usually, the drying is carried out by heating, and the heating temperature may be, for example, 50 to 200 ℃ (for example, 60 to 150 ℃), preferably about 70 to 100 ℃ (for example, 80 to 90 ℃).

The remaining amount of the binder may be adjusted to, for example, about 30 mass% or less (for example, about 20 mass% or less), preferably about 15 mass% or less (for example, about 10 mass% or less), and more preferably about 5 mass% or less (for example, about 1 mass% or less) of the whole of the granular CMC or salt thereof after drying.

(grinding step)

After drying, the obtained CMC or salt thereof may be pulverized by a pulverization step as necessary to adjust the particle size. The pulverization can be carried out by a conventional pulverizer (or an intermediate pulverizer) which can pulverize into a size of about several hundred micrometers, for example, a roll crusher, a cone crusher, a chopper, a stamp mill, an autogenous mill, a stone mill type pulverizer, a mortar, a mill mixer, a ring mill, or the like; a pulverizer (a micro-pulverizer or a super-micro pulverizer) which can pulverize to several hundred μm or less, such as a roll mill, a jet mill, a high-speed rotary mill (a hammer mill, a pin mill, etc.), a container-driven pulverizer (a rotary mill such as a ball mill, a tube mill, a rod mill, etc., a vibration mill, a planetary mill, etc.), a media-agitation type pulverizer (an attritor, a sand mill, etc.), and the like. These pulverizers may be used alone, or two or more kinds may be used in combination. In these crushers, a medium crusher such as a chopper is generally used.

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

The pulverizing time may be selected depending on the type of the pulverizer, and may be, for example, about 10 seconds to 1 hour (e.g., about 30 seconds to 30 minutes), and preferably about 1 to 10 minutes (e.g., about 1 to 3 minutes).

(classifying step)

In many cases, the obtained granular CMC or salt thereof is classified (or sieved) by the classification step to adjust the grain size (and roundness) to a desired level. The classification method may be a conventional method, and examples thereof include: classification using the principle of fluid mechanics [ dry classification (gravity classification, inertia classification, centrifugal classification, etc.), wet classification (sedimentation classification, mechanical classification, hydraulic classification, centrifugal classification, etc.), etc. ], sieving, etc. These classification methods may be used alone, or two or more kinds may be used in combination. Of these, classification is usually performed by sieving in most cases.

In the case of classifying by sieving, usually, the granulated CMC or salt thereof is classified by stacking sieves in order to increase the mesh size in order on a sieve having the smallest mesh size among a plurality of sieves having different mesh sizes. The particles separated by the sieving may be particles passing through a sieve having a mesh size of, for example, 500. mu.m, preferably 400. mu.m, more preferably 300. mu.m, still more preferably 200. mu.m, particularly preferably about 180. mu.m, and particles not passing through a sieve having a mesh size of, for example, 90. mu.m, preferably about 100. mu.m.

Thus, the CMC or salt thereof of the present invention can be prepared. The present invention also includes a method for improving the solubility of CMC or a salt thereof in water by adjusting the particle size distribution (and circularity) of CMC or a salt thereof to a predetermined range by the above method.

[ aqueous composition and Process for producing the same ]

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

Generally, water is mostly pure water. The pH of the aqueous composition may be acidic, but is usually neutral or basic (particularly neutral) in many cases.

The aqueous composition may also comprise other ingredients than CMC or its salts and water. For example, when CMC or a salt thereof is used as an electrode material (a thickener, a dispersion stabilizer, or the like), the aqueous composition may contain another electrode material such as an active material (for example, natural graphite, artificial graphite, hard carbon, a carbon material such as MCMB (mesophase spherule), lithium titanate, or the like), a binder (styrene butadiene copolymer, or the like).

The aqueous composition may be prepared by mixing the CMC or salt thereof, the water, and the other components used as needed. The order and method of mixing are not particularly limited, but from the viewpoint of effectively suppressing the formation of lumps, it is preferable to add CMC or a salt thereof while stirring water with a stirrer or the like (particularly, to add CMC or a salt thereof slowly or a small number of times).

The stirring speed (the number of revolutions of the stirrer or the stirring paddle) when adding CMC or its salt to water may be, for example, about 10 to 2000rpm (e.g., about 100 to 1500rpm), preferably about 500 to 1000rpm (e.g., about 600 to 900rpm), and more preferably about 650 to 850rpm (e.g., about 700 to 800 rpm). After the addition of CMC or a salt thereof is completed, stirring is usually performed until the dissolution is completed (or the stirring torque is stabilized) in many cases. The stirring speed after the end of the addition may be the same as or higher than the stirring speed at the time of the addition, but the stirring may be carried out slowly, and may be, for example, about 10 to 1000rpm (e.g., about 50 to 800rpm), preferably about 100 to 500rpm (e.g., about 150 to 450rpm), and more preferably about 200 to 400rpm (e.g., about 250 to 350 rpm). In the present invention, the dissolution time can be effectively shortened even with slow stirring.

Examples of the shape of the paddle of the mixer include: turbine blades (e.g., edged turbine blades, flat or inclined turbine blades (fan turbine blades, disk turbine blades, etc.), paddle blades (e.g., flat paddle blades, tilt paddle blades, etc.), propeller blades, fardel (Pfaudler) blades, anchor blades (e.g., frame paddles, etc.), band paddles (or ribbon paddles) (e.g., multi-band blades such as twin-band blades, single-band blades, etc.), and the like. These stirring paddles may be used alone, or two or more kinds may be used in combination. Among these stirring paddles, a ribbon paddle is preferable.

It should be noted that each aspect disclosed in the present specification may also be combined with any other feature disclosed in the present specification.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[ raw materials ]

CMC-Na: sodium carboxymethylcellulose, "CMC Daicel model 2200" manufactured by Daicel FineChem co., ltd., degree of etherification (DS): 0.90, and 1 mass% aqueous solution viscosity (25 ℃, 60 rpm): 1800mPa · s.

[ evaluation method ]

(dissolution time)

220g of pure water was measured in a cylindrical glass vessel having a diameter of 55mm and a depth of 130mm, the temperature was adjusted to 25 ℃ in a thermostatic bath, and a Torque Meter ("Rotary Torque Meter TYPE YT" manufactured by New eastern science corporation) and a stirrer (Three-one-motor BL1200 "manufactured by New eastern science corporation) having a ribbon TYPE stirring paddle were attached to the cylindrical glass vessel. The ribbon-type paddle is as follows: bandwidth: 3mm, height: 80mm, width (width in the vertical direction with respect to the rotation axis): 40mm, number of paddles: single, ribbon spiral times: 3 times (shape of tape wrapped around three circles by 80mm in height direction). While stirring the pure water at 750rpm, the sample was slowly added in an amount of 0.8 mass% (about 1.77g) over 5 to 10 seconds. Immediately after the addition, the stirring speed was changed to 300rpm, the time measurement was started, and the time taken until the torque value stabilized at the given value was taken as the dissolution time. The maximum torque achievement rate is calculated as follows: the torque value stabilized at the predetermined value is used as a reference (100%), and the maximum torque achievement rate is calculated in proportion to the torque value.

(particle size distribution and roundness)

The particle size distribution and circularity distribution of the obtained sample were measured using "morpholog 3" manufactured by Malvern corporation, D10, D50 and D90 were calculated from the particle size distribution, and the respective proportions of particles having circularity of 50% or more, 70% or more and 90% or more were calculated from the circularity distribution. In this case, arbitrary particles with a sample number of N5000 were subjected to statistical processing. The particle size distribution is a volume-based distribution, and the roundness distribution is a volume-based distribution.

The circularity is calculated as follows.

Roundness [% ] -4 π × A/P × 100

Examples 1 to 2 and reference examples 1 to 3

(preparation of granulated CMC-Na)

200g of CMC-Na was charged into a granulator ("Mochatsukiki AFC-283" manufactured by Toshiba, Ltd.), and pure water was sprayed once with a 5-second draw bar while the nozzle part was pressed to the maximum extent with stirring using a sprayer ("No. 503" manufactured by Furupla, Ltd.) to obtain a spray. Pure water was added so as to reach 90 mass% (180g) based on the amount of CMC-Na. Drying was carried out at 85 ℃ by using a full-exhaust type dryer ("SPH-301S" manufactured by ESPEC corporation) until the amount of pure water (water content) at 85 ℃ was 10 mass% or less relative to the total amount of CMC-Na and pure water. After drying, the obtained sample was pulverized for 2 minutes using "Force Mill" manufactured by osaka chemical corporation.

(grading of granulated CMC-Na)

On the tray, 330, 166, 83, 30 and 16 mesh sieves (JIS standard test sieve (JIS Z8801)) were stacked in this order from the sieve having a smaller mesh (in the order described above). The granulated sample was added to the uppermost sieve (16-mesh sieve), covered with a lid, and sieved by shaking for 5 minutes with a microSHIFT 300 manufactured by DALTON corporation. The classified CMC-Na was taken out as a sample for evaluation in examples 1 to 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.

The relationship between the mesh and the mesh size of the sieve used is shown in table 1, and the evaluation results are shown in table 2 and fig. 1 to 3. In Table 2, "pass" and "on" indicate passage through the sieve or non-passage through the sieve, respectively, and thus, for example, "30-mesh pass 83-mesh on product" in example 1 means CMC-Na which passed through the 30-mesh sieve but did not pass through the 83-mesh sieve. In addition, "example 1+ example 2 (combination)" shown in FIGS. 2 to 3 indicates the results of mixing and measuring the CMC-Na obtained in examples 1 and 2 (i.e., 30 mesh pass 166 mesh on product).

[ Table 1]

As is clear from table 2 and fig. 1 to 3, in comparative example 1 and reference example 3 containing particles that are too small as compared with examples 1 to 2, or reference example 1 containing particles that are too large, lumps are likely to be generated and dissolution takes a long time, whereas in examples 1 to 2 and reference example 2, dissolution takes a short time as compared with comparative example 1. In particular, in examples 1 to 2, the generation of pimples was not confirmed, and the dissolution time was reduced to 1/6 or less compared to comparative example 1.

In comparative example 1 in which the dissolution time was long, there was a possibility that the proportion of cotton-like material was large because granulation was not performed, and in reference example 1, the proportion of particles in which the shape was deformed was large although granulation was performed, whereas in examples 1 to 2 in which the dissolution time was short, the proportion of particles with high circularity was large compared to the other examples.

Industrial applicability

Since the carboxymethyl cellulose or a salt thereof of the present invention can be dissolved with good efficiency even with slow stirring, it can be used for various applications such as: drugs (e.g., tablets, laxatives, medicines for drinking (syrup and the like), dressings, cooling sheets, X-ray contrast agents, denture stabilizers and the like), cosmetics (e.g., hair care products (shampoo, hair conditioner and the like), skin care products or basic cosmetics (gel and the like), hair dyes and the like), daily necessities (e.g., toothpaste, perfume, body wash, hydrolyzed paper and the like), foods (e.g., beverages, fruit juice, raw or cool surfaces, seasoning juice and the like), electrodes (e.g., negative electrodes) of electric/electronic parts [ e.g., secondary batteries such as batteries and the like ], civil or architectural materials (e.g., oil or hot spring drilling materials, mud agents (or mud water adjusting agents) in the construction of underground diaphragm walls/cast piles (foundation piles), earth pressure shield methods and the like), mud additives and the like), sizing agents (e.g., warp sizing agents, back sizing agents, etc.), breeding feeds, firebricks, and thickeners or dispersants for various slurries.

In particular, since the carboxymethyl cellulose or a salt thereof of the present invention can be dissolved in a short time even if it has a large molecular weight (or even if it has a high viscosity in a solution state), it can be effectively used, for example, as an electrode material (or an additive) for forming an electrode of a battery such as a secondary battery [ for example, a thickener, a dispersant (a dispersion stabilizer or a stabilizer), a fluidizing agent, a binder (or a binder), a suspending agent, etc. ], in particular, as a negative electrode material (for example, a thickener, a dispersant and/or a binder) of a lithium ion battery.

Claims

1. A carboxymethyl cellulose or a salt thereof, which is a granular carboxymethyl cellulose or a salt thereof,

in the volume-based cumulative distribution of the particle diameters of the carboxymethyl cellulose or the salt thereof, when the particle diameters of 10% cumulative, 50% cumulative and 90% cumulative from the small particle diameter side are respectively D10, D50 and D90, D10 is 90 μm or more, D50 is 120 to 470 μm, and D90 is 500 μm or less.

2. The carboxymethyl cellulose or a salt thereof according to claim 1,

d10 is more than 100 μm, D50 is 150-200 μm, and D90 is less than 250 μm.

3. The carboxymethyl cellulose or a salt thereof according to claim 1 or 2,

the proportion of particles having a circularity of 50% or more is 90% by volume or more based on the whole,

the proportion of particles having a roundness of 70% or more is 70% by volume or more based on the whole.

4. The carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 3,

the proportion of particles having a circularity of 50% or more is 95% by volume or more based on the whole,

the proportion of particles having a roundness of 70% or more is 80% by volume or more based on the whole.

5. The carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 4, which has a viscosity of 1500 to 3000 mPa-s in a 1 mass% aqueous solution at a temperature of 25 ℃.

6. The carboxymethyl cellulose or a salt thereof according to any one of claims 1 to 5, which is an electrode material.

7. An aqueous composition comprising:

the carboxymethyl cellulose or the salt thereof according to any one of claims 1 to 6, and

and (3) water.

8. A method for producing an aqueous composition according to claim 7, comprising:

the aqueous composition according to claim 7 is produced by mixing the carboxymethyl cellulose or the salt thereof according to any one of claims 1 to 6 with water.

9. A method of increasing the solubility of carboxymethylcellulose or a salt thereof in water, the method comprising:

carboxymethyl cellulose or a salt thereof is prepared in the form of granules according to any one of claims 1 to 4 to improve its solubility in water.