KR102217137B1 - Carbon black dispersion and use thereof - Google Patents

Abstract

An object of the present invention is to provide a carbon black dispersion using N-methyl-2-pyrrolidone as a solvent, which has excellent dispersibility and storage stability with low viscosity and high concentration compared to conventional resin type dispersants. Another object of the present invention is to provide a battery electrode mixture layer having homogeneous and good coating properties and low surface resistance, and a lithium ion secondary battery comprising the same.
In order to solve the above problems, the carbon black dispersion of the present invention is a carbon black dispersion comprising carbon black, polyvinyl alcohol (or in combination with a pigment derivative) as a dispersant, and N-methyl-2-pyrrolidone as a solvent. , When the saponification degree of polyvinyl alcohol is 60-85 mol%, the BET specific surface area of carbon black is X ㎡/g, and the addition amount of polyvinyl alcohol to 1 g of carbon black is aX g, a is 0.00017 ≤ a It is characterized in that the range of ≤ 0.00256.

Description

Carbon black dispersion and use thereof {Carbon black dispersion and use thereof}

The present invention relates to a carbon black dispersion having excellent dispersibility and storage stability. It also relates to a battery electrode mixture layer and a lithium ion secondary battery using the dispersion.

In the battery field, carbon black is widely used as a conductive aid. In order to shorten the production process when forming the battery electrode mixture layer, how much high concentration of carbon black is uniformly dispersed in a solvent so that it can be easily coated? It is important.

In recent years, especially in consideration of the environment and production cost, by producing a carbon black dispersion that is uniformly dispersed at a higher concentration than before, it is required to reduce the amount of solvent used and to reduce the energy used during drying.

Since these demands have a great influence on the cost of the solvent and the energy used during drying, the higher the cost of the solvent to be used or the higher the boiling point of the solvent to be used, the more important it becomes. N-methyl-2-pyrrolidone used in non-aqueous secondary batteries is expensive compared to general solvents, and has a very high boiling point above 200℃, so it requires a lot of energy when recovering the solvent. There is a strong demand for reduction in the amount of solvent used.

In order to disperse a large amount of carbon black in a solvent, it is particularly effective to adsorb a dispersant on the surface of the carbon black to make the dispersion stable, and carbon black dispersions using various dispersants have been proposed.

For example, Patent Documents 1 and 2 describe a composition for a battery in which carbon black is dispersed while adsorbing an acidic or basic organic dye derivative with respect to the carbon black, thereby achieving dispersion stabilization without impairing the conductivity of the carbon black. However, when a carbon black dispersion (hereinafter referred to as an electrode mixture solution) containing an electrode active material obtained by using an organic dye derivative as a dispersant is coated on a coating substrate, the adhesion between the electrode mixture layer and the coating substrate may be insufficient. There is a problem that the electrode mixture layer may be unintentionally peeled off from the coating substrate.

In order to solve the problem of tightness, for example, in Patent Document 3, as a dispersant for dispersing carbon black, a dye derivative type dispersant and a high molecular polymer type dispersant (hereinafter referred to as a resin type dispersant) are used in combination to induce a dye. It is described that a positive electrode plate having good adhesion can be produced while utilizing the performance as a dispersing agent possessed by the body type dispersant. In particular, it is described that when an oxazine derivative is used as a dye derivative type dispersant and polyvinylbutyral is used in combination as a resin type dispersant in a specific ratio range, it is compatible with respect to the balance of viscosity and adhesion of the positive electrode mixture solution.

However, resin-type dispersants such as polyvinyl acetal, which are known as a dispersant for dispersing carbon black using N-methyl-2-pyrrolidone as a solvent, do not have sufficient performance as a dispersant, so that the concentration of the carbon black dispersion is improved. In order to improve storage stability, it was necessary to add a large amount of a dye derivative type dispersant as a dispersant. Further, for example, as described in Patent Document 5, polyvinyl acetal has a problem in that the resistance to non-aqueous electrolyte solutions such as ethylene carbonate and propylene carbonate is low.

When a polymer that is easily soluble in a non-aqueous electrolyte such as polyvinyl acetal is used as the dispersant, depending on the type and composition of the non-aqueous electrolyte used in the secondary battery, the dispersant has insufficient resistance to the non-aqueous electrolyte and the coating film properties are not stable. Because there is a risk of not being able to do so, there is a need to develop a resin-type dispersant that has higher resistance to non-aqueous electrolytes, has stable coating properties of the resulting coating film, and has more excellent ability as a dispersant in an N-methyl-2-pyrrolidone solvent. Was becoming.

On the other hand, Patent Documents 5 and 6 describe a coating liquid containing carbon black, unmodified or modified polyvinyl alcohol, and N-methyl-2-pyrrolidone, and Patent Document 5 discloses a positive electrode active material or It is described that an electrode plate of a lithium ion secondary battery is prepared by adding a negative electrode active material. However, polyvinyl alcohols in these Patent Documents 5 and 6 are used in large amounts as a binder (resin binder), and there is no technical idea that polyvinyl alcohols are used as a dispersant.

Further, in Patent Documents 3 and 4, the possibility of using polyvinyl alcohol as one of the dispersants and N-methyl-2-pyrrolidone as one of the solvents is suggested. However, although the physical and chemical properties of the carbon black, solvent type and dispersant used are closely related to each other, polyvinyl alcohols having certain physical and chemical properties when a specific solvent called N-methyl-2-pyrrolidone is used. It is not mentioned at all whether or not it can function well as a dispersant, and the relationship between the conditions for functioning as a resin-type dispersant, such as molecular structure, functional group ratio, molecular weight, etc., which are parameters characterizing the original polymer, was still unknown.

General fully saponified polyvinyl alcohol is insoluble in N-methyl-2-pyrrolidone and does not function as a dispersant, and also functions sufficiently as a dispersant in the same manner for polyvinyl esters such as polyvinyl acetate, which is a precursor material thereof. The inventor discovered that it does not.

In general, in the case of dispersing carbon black using a dispersant, if the amount of dispersant is extremely small, the dispersibility of carbon black deteriorates. Conversely, if the amount of dispersant is very large, the dispersibility becomes good. It is expected that the resistance of the resin type dispersant to a non-aqueous electrolyte solution is not sufficient, and the dispersant functions as an insulating component to increase the resistance value, thereby exerting an adverse effect on the battery characteristics.

However, no examples have been reported in detail regarding the physical and chemical properties of carbon black, solvent type, and dispersant used to obtain a carbon black dispersion that is uniformly dispersed at a high concentration, as well as their quantitative relationship. N-methyl-2-pyrrolidone as a specific solvent and polyvinyl alcohol as a dispersant, or N-methyl-2-pyrrolidone as a specific solvent and polyvinyl alcohol and pigment derivatives as a dispersant (organic dye Derivatives or triazine derivatives), the physical and chemical properties of the carbon black and the dispersant, and furthermore, their quantitative relationship, has not been examined at all on how the carbon black dispersion, the battery electrode mixture layer, and the battery characteristics are affected. It was in fact not.

Further, in order to produce a coating film having good conductivity while suppressing the proportion of the conductive material contained in the coating film, the selection of the type of carbon black itself is sometimes important. In general, it is known that when carbon black having a small primary particle diameter and a high specific surface area or carbon black having a small volume density and a high specific surface area is used, a coating film having good conductivity and a low surface resistance value can be obtained. However, since these carbon blacks have a high specific surface area, it has been difficult to stably disperse or improve storage stability.

In addition, in general, when manufacturing an electrode for a lithium ion secondary battery, the solvent used in the preparation of the electrode mixture solution is determined by the polymer material used for the binder in the battery. Currently, in the production of an electrode for a lithium ion secondary battery, polyvinylidene fluoride as a particularly suitable binder for forming an electrode, and N-methyl-2-pyrrolidone as a solvent for dissolving polyvinylidene fluoride are generally used. N-methyl-2-pyrrolidone has a very high boiling point of 202°C, and therefore, a large amount of energy and time was required to dry the electrode mixture solution. In order to solve this problem, attempts have been made to obtain an electrode mixture solution having a high concentration as possible using N-methyl-2-pyrrolidone as a solvent. As another performance required for the carbon black dispersion for an electrode mixture solution of a lithium ion secondary battery, the preferable addition amount of the dispersant is very small. This is because the proportion of other electrode constituents in the electrode film decreases as the dispersant is added.

International Publication No. 2008/108360 Japanese Patent Publication No. 2009-26744 Japanese Patent Publication No. 2013-89485 Japanese Patent Laid-Open No. 2011-70908 International Publication No. 2009/147989 International Publication No. 2011/024799

In view of the above situation, in the present invention, the carbon black dispersion obtained as compared to the conventionally known resin-type dispersant is significantly lowered, that is, the achievable carbon black concentration is remarkably high, and the dispersibility of the carbon black and the storage stability of the dispersion. It is a problem to provide this excellent carbon black dispersion using N-methyl-2-pyrrolidone as a solvent. In addition, it is an object to provide a battery electrode mixture layer that is homogeneous and has good coating properties and low surface resistance. In addition, it is a subject to provide a battery electrode mixture layer that is homogeneous and has good coating properties and low surface resistance, has good resistance of a resin type dispersant to a non-aqueous electrolyte, and has stable coating properties.

(1) the first invention

The present inventors focused on the physical and chemical properties of carbon black, solvent type, and dispersant, and studied their quantitative relationship in detail. As a result, the dispersibility between the specific surface area of carbon black and the amount of polyvinyl alcohol having a specific degree of saponification It has been found that there is a critical range that contributes greatly, and when these are within a certain range, it has been found that a carbon black dispersion having high concentration, low viscosity and long-term storage stability can be produced, and the present invention has been completed.

That is, an embodiment of the present invention is a carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and N-methyl-2-pyrrolidone as a solvent, and the saponification degree of polyvinyl alcohol is 60 to 85 mol%. , When the BET specific surface area of carbon black is X m 2 /g and the addition amount of polyvinyl alcohol to 1 g of carbon black is a X g, a is in the range of 0.00017 ≤ a ≤ 0.00256. will be.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol is 0.65 parts by weight or more and 15 parts by weight or less based on 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol is 2 parts by weight or more and 8 parts by weight or less based on 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to a carbon black dispersion for batteries comprising a positive electrode active material or a negative electrode active material in addition to the carbon black dispersion.

In addition, an embodiment of the present invention relates to a battery electrode mixture layer formed by applying the carbon black dispersion or the battery carbon black dispersion.

In addition, an embodiment of the present invention is a lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein at least one of the positive electrode and the negative electrode is It relates to a lithium ion secondary battery comprising the battery electrode mixture layer.

(2) the second invention

In addition, the present inventors focused on the physical and chemical properties of carbon black, solvent type, and dispersant, and as a result of examining their quantitative relationship, carbon black, organic dye derivative or triazine derivative, and the repeating unit represented by the following formula (A) were polymerized. There is a critical range that greatly contributes to dispersibility between the amount of polyvinyl alcohol used in a specific ratio in the chain, and when they are within a certain range, a carbon black dispersion having high concentration, low viscosity and long-term storage stability can be prepared. Moreover, it was found that a battery electrode mixture layer having a low surface resistance value and excellent resistance to a non-aqueous electrolyte solution of a dispersant was obtained, and the present invention was completed.

That is, an embodiment of the present invention is a carbon black dispersion containing carbon black, polyvinyl alcohol and triazine derivative or polyvinyl alcohol and organic dye derivative as a dispersant, and N-methyl-2-pyrrolidone as a solvent. It relates to a carbon black dispersion, characterized in that the total amount of the dispersant to 100 parts by weight of black is 50 parts by weight or less, and the polyvinyl alcohol contains 50 to 95 mol% of the repeating unit represented by the following formula (A) in the polymer chain.

[Formula A]

In addition, an embodiment of the present invention is a carbon black dispersion containing carbon black, polyvinyl alcohol and triazine derivatives or polyvinyl alcohol and organic dye derivatives as a dispersant, and N-methyl-2-pyrrolidone as a solvent,

When the total amount of the dispersant to 100 parts by weight of carbon black is 50 parts by weight or less, the BET specific surface area of carbon black is X m 2 /g, and the amount of polyvinyl alcohol added to 1 g of carbon black is aX g, a is 0.00017 It is in the range of ≤a≤0.00256, and polyvinyl alcohol contains 50 to 95 mol%, preferably 60 to 85 mol% of the repeating unit represented by the above formula A in the polymer chain. .

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the dispersant is polyvinyl alcohol and a triazine derivative.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol contains 55 to 85 mol% of the repeating unit represented by Formula A in the polymer chain.

Further, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the total amount of the dispersant is 0.5 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol is 0.2 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol is 0.2 parts by weight or more and 8 parts by weight or less based on 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to a carbon black dispersion for batteries comprising a positive electrode active material or a negative electrode active material in addition to the carbon black dispersion.

In addition, an embodiment of the present invention relates to a battery electrode mixture layer formed by applying the carbon black dispersion or the battery carbon black dispersion.

In addition, an embodiment of the present invention is a lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein at least one of the positive electrode and the negative electrode is It relates to a lithium ion secondary battery comprising the battery electrode mixture layer.

(3) the third invention

In addition, the present inventors focused on the physical and chemical properties of carbon black, solvent type, and dispersant, and as a result of examining in detail their quantitative relationship, dispersion between the specific surface area of carbon black and the amount of polyvinyl alcohol having a specific degree of saponification It has been found that there is a critical range that greatly contributes to the property, and when they are within a certain range, it has been found that a carbon black dispersion having high concentration, low viscosity and long-term storage stability can be produced, and the present invention has been completed.

That is, an embodiment of the present invention is a carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and N-methyl-2-pyrrolidone as a solvent, and the saponification degree of polyvinyl alcohol is 60 to 85 mol%. , It relates to a carbon black dispersion, characterized in that the BET specific surface area of the carbon black is 30 to 1,500 m 2 /g, and the polyvinyl alcohol per 100 parts by weight of carbon black exceeds 8 parts by weight and is 40 parts by weight or less.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the polyvinyl alcohol is more than 8 parts by weight and 25 parts by weight or less based on 100 parts by weight of carbon black.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the BET specific surface area of the carbon black is 200 to 1,500 m 2 /g.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the BET specific surface area of the carbon black is 500-1,500 m 2 /g.

Further, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the carbon black is hollow carbon black.

In addition, an embodiment of the present invention relates to the carbon black dispersion, characterized in that the content of polyvinyl alcohol is 0.05 parts by weight or more and less than 2 parts by weight based on 100 parts by weight of the total amount of solid components contained in the dispersion.

In addition, an embodiment of the present invention relates to a carbon black dispersion for batteries comprising a positive electrode active material or a negative electrode active material in addition to the carbon black dispersion.

In addition, an embodiment of the present invention relates to a battery electrode mixture layer formed by applying the carbon black dispersion or the battery carbon black dispersion.

In addition, an embodiment of the present invention is a lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein at least one of the positive electrode and the negative electrode is It relates to a lithium ion secondary battery comprising the battery electrode mixture layer.

According to the first and third inventions, a carbon black dispersion having a significantly lower viscosity than the case of using a conventionally known resin type dispersant can be obtained, and the carbon black concentration can be increased.

According to the second invention, a coating film having better adhesion to the coating substrate can be obtained than when a conventionally known pigment derivative type dispersant is used alone, and more than when a conventionally known resin type dispersant is used alone or in combination with a pigment derivative. A carbon black dispersion having a remarkably low viscosity can be obtained, and it becomes possible to increase the carbon black concentration while maintaining adhesion.

In addition, according to the first, second and third inventions, it is possible to provide a carbon black dispersion having a higher concentration than the conventional one, and at the same time, the amount of the N-methyl-2-pyrrolidone solvent used can be significantly reduced. The drying process of one coat can also be drastically shortened. In addition, it becomes possible to provide a carbon black dispersion using N-methyl-2-pyrrolidone as a solvent, which is excellent in the dispersibility of carbon black and the storage stability of the dispersion.

In addition, when the above dispersion is used to prepare an electrode mixture for secondary batteries, it is easy to add or knead the electrode active material powder because of its low viscosity, and a homogeneous and good coating film can be obtained even when an electrode mixture solution having a high concentration of each electrode component is used. Therefore, it becomes possible to obtain a battery electrode mixture layer having a low surface resistance value. In addition, when a battery electrode mixture layer is produced by using the dispersion, resistance to a non-aqueous electrolyte solution becomes good, and a battery electrode mixture layer having more stable coating properties can be obtained.

The details of the present invention (the first, second and third inventions) will be described below. In the present specification, "carbon black dispersion" and "battery carbon black dispersion" are referred to as "dispersion", and "organic pigment derivatives or triazine derivatives" are referred to as "pigment derivatives" and "polyvinyl alcohol" (first and third inventions). Alternatively, "polyvinyl alcohol and pigment derivative" (second invention) may be abbreviated as "dispersant" and "N-methyl-2-pyrrolidone" may be abbreviated as "NMP".

<Carbon Black>

As carbon black, commercially available hollow carbon black, furnace black, channel black, thermal black, acetylene black, Ketjen black, etc., and various kinds of carbon black, and also commonly used oxidation-treated carbon black, graphitized carbon black, carbon nanotube, Carbon nanofibers, etc. can also be used. In addition, carbon black having high conductivity such as acetylene black or furnace black, and industrially produced carbon black is suitably used.

Oxidation of carbon black is performed by treating carbon black at high temperature in air, or secondary treatment with nitric acid, nitrogen dioxide, ozone, etc., so that, for example, oxygen-containing polar functional groups such as phenol, quinone, carboxyl, and carbonyl groups are performed on the surface of the carbon black. It is a treatment that is directly introduced into (covalently bonded) to, and is generally performed to improve the dispersibility of carbon black.

The average primary particle diameter of the carbon black used in the preparation of the dispersion is preferably 0.01 to 1 µm, particularly preferably 0.01 to 0.2 µm, as in the range of the average primary particle diameter of the carbon black used in general dispersions or paints. -0.1 µm is more preferable. The average primary particle diameter here refers to the arithmetic average particle diameter measured by an electron microscope, and this property value is generally used to indicate the physical properties of carbon black.

As other physical property values indicating the physical properties of carbon black, the BET specific surface area and pH are known. BET specific surface area refers to the specific surface area measured by the BET method by nitrogen adsorption (hereinafter, simply described as the specific surface area), and this specific surface area corresponds to the surface area of carbon black, and the larger the specific surface area, the greater the amount required for a dispersant. There are many. pH changes under the influence of functional groups or impurities contained on the surface of carbon black.

The carbon black used in the first and second inventions preferably has a BET specific surface area of 20 to 1,500 m2/g, more preferably 20 to 1,000 m2/g, and even more preferably 20 to 500 m2/g. , It is more preferable that it is 20-250 m2/g, it is more preferable that it is 30-150 m2/g, and it is especially preferable that it is 30-75 m2/g. In the case of carbon black having the BET specific surface area, various commercial products and synthetic products may be used alone or two or more types of carbon black may be used together.

The carbon black used in the first and second inventions is not particularly limited as long as it has the above specific surface area, but has high conductivity, such as acetylene black, furnace black, hollow carbon black, or graphitized carbon black, and is produced industrially. Carbon black that is used is suitably used. Among these carbon blacks, acetylene black is particularly suitably used. Examples of acetylene black include Denka Black (manufactured by Denki Chemical Industry Co., Ltd.), and various grades can be obtained as commercial items.

Carbon black used in the third invention preferably has a BET specific surface area of 30-1,500 m2/g, more preferably 200-1,500 m2/g, more preferably 500-1,500 m2/g, and 500- It is particularly preferred that it is 1,000 m 2 /g. In the case of carbon black having the BET specific surface area, various commercial products and synthetic products may be used alone or two or more types of carbon black may be used together.

In addition, the BET specific surface area of the carbon black prepared by mixing two or more types of carbon black is the BET specific surface area of a certain carbon black (i) as S _i , and the ratio of which carbon black (i) to the total carbon black is G _i . It can be calculated based on the following formula as the sum of the product of the BET specific surface area and the ratio of each carbon black species at the time.

(BET specific surface area of mixed carbon black) =Σ(S _i ·G _i )

For example, the specific surface area of carbon black prepared by mixing carbon black with a BET specific surface area of 800 m 2 /g and carbon black of 1,200 m 2 /g at a weight ratio of 1 to 1 is 1,000 m 2 /g.

The carbon black used in the third invention is not particularly limited as long as it has the above specific surface area, but has high conductivity such as acetylene black, furnace black, hollow carbon black or graphitized carbon black, and is also industrially produced. Is used suitably. Among these carbon blacks, hollow carbon blacks having excellent conductivity per weight are particularly suitably used. Examples of the hollow carbon black include Ketjen Black (manufactured by Arc Irradiation), and various grades can be obtained as commercial products.

<Polyvinyl alcohol>

Polyvinyl alcohol is used as a dispersant. That is, polyvinyl alcohol is used not as a binder but as a dispersant. The method for producing polyvinyl alcohol is not particularly limited, but polyvinyl alcohol obtained by using polyvinyl acetate as a raw material and saponifying it will be described below.

In general, polyvinyl alcohol is obtained by using polyvinyl acetate obtained by polymerizing vinyl acetate as a raw material, and saponifying the polyvinyl acetate to replace the acetyl group with a hydroxyl group. For this synthesis process, polyvinyl alcohol has an acetyl group and a hydroxyl group, and the ratio is expressed as the degree of saponification.

In addition, the degree of saponification is the same as the definition of the degree of saponification known in the industry, and the vinyl alcohol unit with respect to the total number of moles of the structural unit (typically a vinyl ester unit) and the vinyl alcohol unit that can be converted into a vinyl alcohol unit by saponification. It refers to the ratio (mol%) occupied by the number of moles (in other words, the ratio (mol%) of the repeating unit represented by Formula A contained in polyvinyl alcohol). In particular, when polyvinyl acetate is used as a raw material, the number of hydroxyl groups derived from the vinyl alcohol skeleton contained in polyvinyl alcohol is divided by the sum of the number of acetyl groups derived from the vinyl acetate skeleton and the number of hydroxyl groups derived from the vinyl alcohol skeleton. it means.

As polyvinyl alcohol, a polyvinyl ester, especially one obtained by saponifying polyvinyl acetate, is mainly used, but is not limited thereto. Further, the degree of saponification is preferably 50 to 95 mol%, more preferably 55 to 92 mol%, still more preferably 55 to 85 mol%, and particularly preferably 60 to 85 mol%. If the saponification degree is polyvinyl alcohol, various commercially available products and synthetic products may be used alone or in combination of two or more.

In addition, as long as it is within the range of the saponification degree, as a functional group other than a hydroxyl group and an acetic acid group, for example, acetoacetyl group, sulfonic acid group, carboxyl group, carbonyl group, amino group, isocyanate group is introduced, modified by various salts, other anions, or Cationic-modified, unsaturated-modified, acetal-modified by aldehydes (butyral-modified, acetoacetal-modified, formal-modified, etc.), and those with a diol structure introduced are included in the range of usable polyvinyl alcohols. , These may be used alone or in combination of two or more.

Polyvinyl alcohol preferably has an average degree of polymerization of 50 to 4,000, then preferably 50 to 3,000, more preferably 100 to 3,000, particularly preferably 100 to 2,000, and even more preferably 100 to 1,500 Do. In the case of polyvinyl alcohol having the degree of polymerization, various commercially available products and synthetic products may be used alone or in combination of two or more.

In the first invention of the polyvinyl alcohol, the viscosity of a 4% aqueous solution according to JIS K6726 is preferably 2.0 to 25 mPa·s, and more preferably 2.0 to 20.0 mPa·s.

If the degree of saponification is less than 50 mol% to 60 mol%, the solubility in NMP is very good, but the adsorption to carbon black is insufficient, so it is considered to be not effective for dispersion, and the saponification degree is 85 mol% to 95 mol. It is presumed that those larger than% do not dissolve and swell in most of the NMP, so that even if they are adsorbed on carbon black, the polymer chains cannot be tightened on the NMP side, and therefore, effectively steric repulsion cannot be achieved. On the other hand, it is considered to function particularly effectively as a dispersant because the saponification degree is included in these ranges because the balance of dissolution or swelling property in NMP, adsorption property to carbon black, and steric repulsion effect after adsorption is good.

Examples of commercially available polyvinyl alcohol included in the saponification degree range include Kuraray Poval (polyvinyl alcohol manufactured by Kuraray), Gosenol (polyvinyl alcohol manufactured by Nippon Synthetic Chemical Industries, Ltd.), and Denka Poval (Denki Kagaku Kogyo Co., Ltd.). Manufacture), J-Poval (manufactured by Japanese vinyl acetate Poval), etc., and various grades can be obtained from the market.

More specifically, Kuraray Poval's PVA-403 (saponification degree 78.5 to 81.5 mol%, average polymerization degree 300, 4% aqueous solution viscosity 2.8 to 3.3 mPa·s at a liquid temperature of 20°C according to JIS K6726), PVA-505 (Saponification degree 72.5~74.5 mol%, average polymerization degree 500, 4% aqueous solution viscosity 4.2~5.0 mPa·s), L-8 (saponification degree 69.5~72.5 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 5.0~5.8 mPa S), L-9 (saponification degree 69.5~72.5 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 6.0~6.5 mPa·s), L-9-78 (saponification degree 76.5~79.0 mol%, average polymerization degree 1,000 Below, 4% aqueous solution viscosity 6.0~6.7 mPa·s), L-10 (saponification degree 71.5~73.5 mol%, average polymerization degree 1,000 or less), C-506 (saponification degree 74.0~79.0 mol%, average polymerization degree 600, 4%) Aqueous viscosity 4.0 to 6.0 mPa·s), KL-506 (saponification degree 74.0 to 80.0 mol%, average polymerization degree 600, 4% aqueous solution viscosity 5.2 to 6.2 mPa·s), or Gosenol's KL-03 (saponification degree 78.5~ 82.0 mol%, average polymerization degree 500 or less, 4% aqueous solution viscosity 2.8 to 3.4 mPa·s), KL-05 (saponification degree 78.5 to 82.0 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 4.0 to 5.0 mPa·s), NK-05R(Copper 71.0~75.0 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 4.5~5.5 mPa·s), KP-08R(Copper 71.0~73.5 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 6.0~ 8.0 mPa·s), and the like, but are not limited thereto.

<N-methyl-2-pyrrolidone>

NMP is used to manufacture electrodes for lithium ion secondary batteries. In the present invention, one or more other solvents may be used in combination as long as the performance as a dispersant (mainly polyvinyl alcohol alone or a combination of polyvinyl alcohol and pigment derivatives) and battery performance are not impaired, but the industrial use contemplated by the present invention It is preferable to use NMP alone from the possibilities.

<Pigment derivative>

The pigment derivative is an organic dye derivative having an acidic or basic functional group, or a triazine derivative having an acidic or basic functional group.

<Acid pigment derivative>

Among the acidic pigment derivatives, a triazine derivative having an acidic functional group represented by the following formula (1) or an organic dye derivative having an acidic functional group represented by the following formula (4) is particularly preferred.

First, a triazine derivative having an acidic functional group represented by Formula 1 will be described.

[X ¹ is -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -CH ₂ NHCOCH ₂ NH- or -X ³ -YX ^4- And X ² and X ⁴ each independently represent -NH- or -O-, and X ³ represents -CONH-, -SO ₂ NH-, -CH ₂ NH-, -NHCO- or -NHSO _2- , Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, and Z is -SO ₃ M, -COOM, -P(O)(-OM) ₂ Or -OP(O)(-OM) ₂ , M represents 1 equivalent of 1 to trivalent cation, and Q represents -OR ² , -NH-R ² , halogen group, -X ¹ -R ¹ or- X ² -YZ is represented, and R ² represents a hydrogen atom, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent. n represents the integer of 1-4. R ¹ represents an organic dye residue, a heterocyclic residue which may have a substituent, an aromatic ring residue which may have a substituent, or a group represented by the following formula (2).]

[X ⁵ represents -NH- or -O-, X ⁶ and X ⁷ are each independently -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH- or -CH ₂ NHCOCH ₂ represents NH-, and R ³ and R ⁴ each independently represent an organic dye residue, a heterocyclic residue which may have a substituent, an aromatic ring residue which may have a substituent, or -YZ, and Y and Z are represented in the formula (1). It is the same definition as in Y and Z. ]

Examples of the organic dye residues in R ¹ , R ³ , and R ⁴ include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo and polyazo, phthalocyanine dyes, anthraquinone, diaminodiantra Anthraquinone pigments such as quinone, anthrapyrimidine, flavantron, antantrone, indanthrone, pyrantrone, and violantrone, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thioindigo pigments, And residues such as isoindolin-based dyes, isoindolinone-based dyes, quinophthalone-based dyes, indanthrene-based dyes, and metal complex-based dyes. In particular, in order to increase the effect of suppressing the short circuit of the battery due to metal, it is preferable to use organic dye residues other than metal complex dyes, and among them, azo dyes, diketopyrrolopyrrole dyes, metal-free phthalocyanine dyes, Residues of a quinacridone-based dye or a dioxazine-based dye are preferred because they exhibit an effect excellent in dispersibility.

In addition, examples of heterocyclic residues and aromatic ring residues in R ¹ , R ³ , and R ⁴ include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindole, isoindolinone, and benzimi. Heterocyclic residues such as dazolone, benzthiazole, benztriazole, indole, quinoline, carbazole, and acridine, and aromatic ring residues such as benzene, naphthalene, anthracene, fluorene, phenanthrene, and anthraquinone. . In particular, a heterocyclic moiety containing any one of S, N, and O heteroatoms is preferred because it exhibits an effect excellent in dispersibility.

Y in the general formulas (1) and (2) represents an alkylene group, an alkenylene group, or an arylene group which may have a substituent, but is preferably 20 or less carbon atoms and more preferably 10 or less carbon atoms. As a particularly preferred embodiment, a phenylene group, a biphenylene group, a naphthylene group, or an alkylene group which may have a side chain having 10 or less carbon atoms may be mentioned.

Preferred embodiments of the alkyl group which may have a substituent and the alkenyl group which may have a substituent for R ² are those having 20 or less carbon atoms. More preferably, the alkyl group which may have a C10 or less side chain is mentioned. Here, the alkyl group having a substituent and the alkenyl group having a substituent include those in which the hydrogen atom of the alkyl group or alkenyl group is substituted with a halogen group such as a fluorine atom, a chlorine atom, and a bromine atom, a hydroxyl group, a mercapto group, and the like.

M represents 1 equivalent of a 1 to 3 valent cation, for example, a hydrogen ion (proton), a metal cation, or a quaternary ammonium cation. Further, when having two or more M in the structure (one molecule) of the dispersant, M may be only one type of proton, metal cation, and quaternary ammonium cation, or a combination of two or more types. Examples of the metal cations include cations of metals such as lithium, sodium, potassium, calcium, barium, magnesium, aluminum, nickel, and cobalt. As the quaternary ammonium cation, it is a single compound or a mixture having a structure represented by formula (3).

[R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or an aryl group which may have a substituent.]

R ⁵ , R ⁶ , R ⁷ , and R ⁸ may each be the same or different. Further, when R ⁵ , R ⁶ , R ⁷ , and R ⁸ have a carbon atom, the number of carbon atoms is 1 to 40, preferably 1 to 30, and more preferably 1 to 20.

Specific examples of the quaternary ammonium cation include dimethyl ammonium, trimethyl ammonium, diethyl ammonium, triethyl ammonium, hydroxyethyl ammonium, dihydroxyethyl ammonium, 2-ethylhexyl ammonium, dimethylaminopropyl ammonium, lauryl ammonium, stearyl And ammonium, but are not limited thereto.

Next, an organic dye derivative having an acidic functional group represented by Formula 4 will be described.

[X ⁸ is a direct bond, -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -CH ₂ NHCOCH ₂ NH-, -X ⁹ -Y- or -X ^9- YX ¹⁰ -represents, X ⁹ represents -CONH-, -SO ₂ NH-, -CH ₂ NH-, -NHCO- or -NHSO ₂ -, X ¹⁰ represents -NH- or -O-, Y Represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, and Z is -SO ₃ M, -COOM, -P(O)(-OM) ₂ or- OP(O)(-OM) ₂ represents ₂ , M represents 1 equivalent of 1 to trivalent cations, R ⁹ represents an organic dye residue, and n represents an integer of 1 to 4.]

The organic dye residue for R ⁹ is the same definition as the organic dye residue for R ¹ , R ³ and R ⁴ . In particular, in order to increase the effect of suppressing the short circuit of the battery due to metal, it is preferable to use organic dye residues other than metal complex dyes, and among them, azo dyes, diketopyrrolopyrrole dyes, metal-free phthalocyanine dyes, Residues of a quinacridone-based dye or a dioxazine-based dye are preferred because they exhibit an effect excellent in dispersibility.

M in Formula 4 is the same definition as M in Formula 1.

The method for synthesizing the acidic pigment derivative to be used is not particularly limited, but for example, Japanese Patent Publication No. 39-28884, Japanese Patent Publication No. 45-11026, and Japanese Patent Publication No. 45-29755. , Japanese Patent Publication No. 64-5070, Japanese Patent Application Publication No. 2004-217842, etc. can be synthesized by the method described.

<Basic pigment derivative>

Among the basic pigment derivatives, a triazine derivative having a basic functional group represented by the following formula (101) or an organic dye derivative having a basic functional group represented by the following formula (106) are particularly preferred.

First, a triazine derivative having a basic functional group represented by Formula 101 will be described.

X ¹⁰¹ represents -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -CH ₂ NHCOCH ₂ NH- or -X ¹⁰² -Y ¹ -X ¹⁰³ -, and X ¹⁰² Represents -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -NHCO- or -NHSO ₂ -, X ¹⁰³ represents -NH- or -O-, Y ¹ represents an alkylene group which may have a substituent composed of 1 to 20 carbon atoms, an alkenylene group which may have a substituent, or an arylene group which may have a substituent.

P represents a group represented by any one of Formula 102, Formula 103, or Formula 104.

Q ¹⁰¹ represents -OR ¹⁰² , -NH-R ¹⁰² , a halogen group, -X ¹⁰¹ -R ¹⁰¹ or a group represented by any one of Formula 102, Formula 103, or Formula 104.

R ¹⁰² represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

o represents the integer of 1-4.

X ¹⁰⁴ represents a direct bond, -SO ₂ -, -CO-, -CH ₂ NHCOCH ₂ -, -CH ₂ NHCONHCH ₂ -, -CH ₂ -or -X ¹⁰⁵ -Y ¹ -X ¹⁰⁶ -. X ¹⁰⁵ represents -NH- or -O-, and X ¹⁰⁶ represents a direct bond, -SO ₂ -, -CO-, -CH ₂ NHCOCH ₂ -, -CH ₂ NHCONHCH ₂ -or -CH ₂ -.

v ¹ represents the integer of 1-10.

R ¹⁰³ and R ¹⁰⁴ each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group or a heterocyclic residue, and even if R ¹⁰³ and R ¹⁰⁴ are bonded to form a ring do.

R ¹⁰⁵ , R ¹⁰⁶ , R ¹⁰⁷ and R ¹⁰⁸ each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

R ¹⁰⁹ represents an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

R ¹⁰¹ represents an organic dye residue, an optionally substituted heterocyclic residue, an optionally substituted aromatic ring residue, or a group represented by the following formula (105).

T represents -X ¹⁰⁸ -R ¹¹⁰ or W ¹ , and U represents -X ¹⁰⁹ -R ¹¹¹ or W ² .

Each of W ¹ and W ² independently represents -OR ¹⁰² , -NH-R ¹⁰² , a halogen group, or a group represented by any one of Formula 102, Formula 103 or Formula 104.

X ¹⁰⁷ represents -NH- or -O-, X ¹⁰⁸ and X ¹⁰⁹ are each independently -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH- or -CH ₂ NHCOCH ₂ NH-.

R ¹¹⁰ and R ¹¹¹ each independently represent an organic dye residue, an optionally substituted heterocyclic residue, or an optionally substituted aromatic ring residue.

Examples of organic dye residues in R ¹⁰¹ of formula ¹⁰¹ and R ¹¹⁰ and R ¹¹¹ of formula 105 include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, and polyazo, phthalocyanine dyes, and dia. Anthraquinone pigments such as minodianthraquinone, anthrapyrimidine, flavantron, antantrone, indanthrone, pyrantrone, and violantrone, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thioindigo And residues such as a dye based on an isoindolin, a dye based on an isoindolinone, a dye based on quinophthalone, a dye based on human tren, and a dye based on a metal complex. In particular, in order to increase the effect of suppressing a short circuit of the battery due to metal, it is preferable to use an organic dye residue other than a metal complex dye.

Examples of heterocyclic residues and aromatic ring residues in R ¹⁰¹ of Formula ¹⁰¹ and R ¹¹⁰ and R ¹¹¹ of Formula 105 include thiophene, furan, pyridine, pyrazine, triazine, pyrazole, pyrrole, imidazole, iso Indoline, isoindolinone, benzimidazolone, benzthiazole, benztriazole, indole, quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, acridone And the like residues. These heterocyclic residues and aromatic ring residues include alkyl groups (methyl, ethyl, butyl, etc.), amino groups, alkylamino groups (dimethylamino, diethylamino, dibutylamino groups, etc.), nitro groups, hydroxyl groups, alkoxyl groups (methoxy groups, ethoxy groups, etc.). Group, butoxy group), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.), and phenylamino group (alkyl group, amino group, It may have a substituent such as an alkylamino group, a nitro group, a hydroxyl group, an alkoxy group, or a halogen).

R ¹⁰³ and R ¹⁰⁴ each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group or a heterocyclic residue, and even if R ¹⁰³ and R ¹⁰⁴ are bonded to form a ring do. In particular, hydrogen atoms are considered to have a high effect of suppressing metal precipitation in the battery, and thus are preferable. Y ¹ in Formulas 101 and 105 represents an alkylene group, an alkenylene group, or an arylene group which may have a substituent having 20 or less carbon atoms, preferably a phenylene group, a biphenylene group, a naphthylene group, or a carbon number which may have a substituent. The alkylene group which may have a side chain of 10 or less is mentioned.

Next, an organic dye derivative having a basic functional group represented by Formula 106 will be described.

Z ¹⁰¹ is a group represented by Formula 107, Formula 108, or Formula 109 below. m represents the integer of 1-4.

X ²⁴ represents a direct bond, -SO ₂ -, -CO-, -CH ₂ NHCOCH ₂ -, -CH ₂ NHCONHCH ₂ -, -CH ₂ -or -X ²⁵ -Y ² -X ²⁶ -. X ²⁵ represents -NH- or -O-, X ²⁶ represents a direct bond, -SO ₂ -, -CO-, -CH ₂ NHCOCH ₂ -, -CH ₂ NHCONHCH ₂ -or -CH ₂ -. Y ² represents an alkylene group which may have a substituent composed of 1 to 20 carbon atoms, an alkenylene group which may have a substituent, or an arylene group which may have a substituent.

v ² represents the integer of 1-10.

R ²³ and R ²⁴ each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted phenyl group or a heterocyclic residue, and R ²³ and R ²⁴ may be bonded to form a ring. . In particular, hydrogen atoms are considered to have a high effect of suppressing metal precipitation in the battery, and thus are preferable.

R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

R ²⁹ represents an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

R ²² represents an organic dye residue, a heterocyclic residue which may have a substituent, and an aromatic ring residue which may have a substituent.

Examples of the organic dye residue for R ²² include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, and polyazo, phthalocyanine dyes, diaminodianthraquinone, anthrapyrimidine, and flavantron. , Anthraquinone pigments such as anthanthrone, indanthrone, pyrantrone, and violantrone, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thioindigo pigments, isoindolin pigments, isoindoli And residues of non-based pigments, quinophthalone-based pigments, indanthrene-based pigments, and metal complex-based pigments. In particular, in order to increase the effect of suppressing a short circuit of the battery due to metal, it is preferable to use an organic dye residue other than a metal complex dye.

In addition, examples of the heterocyclic residue and aromatic ring residue for R ²² include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, benzthiazole , Benztriazole, indole, quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, and acridone. These heterocyclic residues and aromatic ring residues include alkyl groups (methyl, ethyl, butyl, etc.), amino groups, alkylamino groups (dimethylamino, diethylamino, dibutylamino groups, etc.), nitro groups, hydroxyl groups, alkoxyl groups (methoxy groups, ethoxy groups, etc.). Group, butoxy group), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.), and phenylamino group (alkyl group, amino group, It may have a substituent such as an alkylamino group, a nitro group, a hydroxyl group, an alkoxy group, or a halogen).

As an amine component used to form a substituent represented by Formulas 102 to 104 and Formulas 107 to 109, for example, dimethylamine, diethylamine, methylethylamine, N,N-ethylisopropylamine, N,N- Ethylpropylamine, N,N-methylbutylamine, N,N-methylisobutylamine, N,N-butylethylamine, N,N-tert-butylethylamine, diisopropylamine, dipropylamine, N, N-sec-butylpropylamine, dibutylamine, di-sec-butylamine, diisobutylamine, N,N-isobutyl-sec-butylamine, diamylamine, diisoamylamine, dihexylamine, dicy Chlohexylamine, di(2-ethylhexyl)amine, dioctylamine, N,N-methyloctadecylamine, didecylamine, diallylamine, N,N-ethyl-1,2-dimethylpropylamine, N, N-methylhexylamine, dioleylamine, distearylamine, N,N-dimethylaminomethylamine, N,N-dimethylaminoethylamine, N,N-dimethylaminoamylamine, N,N-dimethylaminobutylamine , N,N-diethylaminoethylamine, N,N-diethylaminopropylamine, N,N-diethylaminohexylamine, N,N-diethylaminobutylamine, N,N-diethylaminopentylamine , N,N-dipropylaminobutylamine, N,N-dibutylaminopropylamine, N,N-dibutylaminoethylamine, N,N-dibutylaminobutylamine, N,N-diisobutylaminopentyl Amine, N,N-methyl-laurylaminopropylamine, N,N-ethyl-hexylaminoethylamine, N,N-distearylaminoethylamine, N,N-dioleyylaminoethylamine, N,N- Distearylaminobutylamine, piperidine, 2-pipecholine, 3-pipecholine, 4-pipecholine, 2,4-rubetidine, 2,6-lupetidine, 3,5-lupetidine, 3-piperidin methanol, pipecholic acid, isonifecotic acid, methyl isonifecotinate, ethyl isonifecotinate, 2-piperidinethanol, pyrrolidine, 3-hydroxypyrrolidine, N-amino Ethylpiperidine, N-aminoethyl-4-pipecholine, N-aminoethylmorpholine, N-aminopropylpiperidine, N-aminopropyl-2-pipecholine, N-aminopropyl-4-pipecholine, N-aminopropylmorpholine, N-methylpiperazine, N-butylpiperazine, N-methylhomopiperazine, 1-cyclopentylpiperazine, 1-amino- 4-methyl piperazine, 1-cyclopentyl piperazine, etc. are mentioned.

The method for synthesizing an organic dye derivative having a basic functional group or a triazine derivative having a basic functional group to be used is not particularly limited, but Japanese Patent Laid-Open Publication No. 54-62227, Japanese Laid-Open Patent Publication No. 56-118462, Japan Japanese Patent Application Publication No. 56-166266, Japanese Patent Application Publication No. 60-88185, Japanese Patent Application Publication No. 63-305173, Japanese Patent Application Publication No. Hei 3-2676, Japanese Patent Application Publication Hei 11- It can be synthesized by the method described in 199796.

For example, an organic dye derivative having a basic functional group is a substituent represented by formulas (110) to (113) in an organic dye, a heterocyclic compound (for example, acridon) or an aromatic ring compound (for example, anthraquinone). After introducing these substituents and amine components (e.g., N,N-dimethylaminopropylamine, N-methylpiperazine, diethylamine or 4-[4-hydroxy-6-[3-(dibutylamino )Propylamino]-1,3,5-triazin-2-ylamino]aniline, etc.) can be synthesized by reacting.

Formula (110) -SO ₂ Cl

Formula (111) -COCl

Formula (112) -CH ₂ NHCOCH ₂ Cl

Formula (113) -CH ₂ Cl

Further, for example, when introducing a substituent represented by formula (110), an organic dye, a heterocyclic compound (eg, acridone) or an aromatic ring compound (eg, anthraquinone) is dissolved in chlorosulfonic acid. A chlorinating agent such as thionyl chloride is reacted, and introduced into an organic dye, a heterocyclic compound (e.g., acridone) or an aromatic ring compound (e.g., anthraquinone) depending on conditions such as reaction temperature and reaction time. The number of substituents represented by the following formula (110) can be adjusted.

In the case of introducing a substituent represented by formula (111), first, an organic dye having a carboxyl group, a heterocyclic compound (eg, acridon) or an aromatic ring compound (eg, anthraquinone) is synthesized by a known method. Then, a method of reacting a chlorinating agent such as thionyl chloride in an aromatic solvent such as benzene, etc. are mentioned.

During the reaction of the substituent represented by Formulas (110) to (113) with the amine component, some of the substituents represented by Formulas (110) to (113) may be hydrolyzed to replace chlorine with a hydroxyl group. In that case, the substituent represented by formula (110) becomes a sulfonic acid group, and the substituent represented by formula (111) becomes a carboxylic acid group, but all may be free acids, and 1 to trivalent metals or salts with the above amines May be formed.

In addition, when the organic dye is an azo dye, a substituent represented by Chemical Formula 107 to Chemical Formula 109 or the following Chemical Formula 114 is introduced into the diazo component or the coupling component in advance, and thereafter, a coupling reaction is performed, thereby It is also possible to prepare derivatives.

X ¹⁰¹ represents -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -CH ₂ NHCOCH ₂ NH- or -X ¹⁰² -Y ¹ -X ¹⁰³ -, and X ¹⁰² Represents -NH-, -O-, -CONH-, -SO ₂ NH-, -CH ₂ NH-, -NHCO- or -NHSO ₂ -, and X ¹⁰³ each independently represents -NH- or -O- And Y ¹ is The alkylene group which may have a substituent which consists of C1-C20, the alkenylene group which may have a substituent, or the arylene group which may have a substituent is shown.

P represents a substituent represented by any one of Formulas 102, 103 or 104.

Q ¹⁰¹ represents -OR ¹⁰² , -NH-R ¹⁰² , a halogen group, -X ¹⁰¹ -R ¹⁰¹ or a substituent represented by any one of Formulas 102, 103 or 104.

R ¹⁰² represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.

In addition, triazine derivatives having a basic functional group include, for example, cyanuric chloride as a starting material, and forming a substituent represented by Chemical Formulas 107 to 109 or 114 in one or more chlorine of cyanuric chloride (for example, For example, it is obtained by reacting N,N-dimethylaminopropylamine or N-methylpiperazine) and then reacting the remaining chlorine of cyanuric chloride with various amines or alcohols.

The pigment derivative to be used is preferably an organic dye derivative having an acidic or basic functional group, or a triazine derivative having an acidic or basic functional group, more preferably a triazine derivative having an acidic or basic functional group, and It is more preferable that it is a triazine derivative having a functional group, and it is particularly preferable that it is a triazine derivative that does not have an azo bond and has an acidic functional group.

The pigment derivative may be used alone or in combination of two or more in an arbitrary ratio. It is believed that the pigment derivative mainly functions as a dispersant and also plays a role in creating an electrode film state suitable for improving battery performance.

<Method for preparing carbon black dispersion>

The dispersion of the present invention is obtained by dispersing carbon black in NMP mainly using polyvinyl alcohol as a dispersant (first and third invention), or polyvinyl alcohol and a pigment derivative as a dispersant (second invention). In this case, by simultaneously or sequentially adding and mixing the dispersant and the carbon black, the dispersant is dispersed while acting on the carbon black (adsorption). However, in order to more easily prepare the carbon black dispersion, it is more preferable to dissolve, swell or disperse the dispersant in NMP, and then add and mix the carbon black in the liquid to cause the dispersant to act (adsorb) on the carbon black. Do. In addition, when powder other than carbon black is used as an electrode mixture solution by adding, for example, an electrode active material for secondary batteries, a dispersant, carbon black and an electrode active material may be simultaneously added to NMP and subjected to dispersion treatment.

As the dispersing device, a dispersing device commonly used for pigment dispersion or the like can be used. For example, mixers such as disper, homo mixer, planetary mixer, and homogenizers (such as M Technic's ``Clear Mix'', PRIMIX ``Fill Mix'', Silverson's ``Abramix'', etc.), Paint conditioner (manufactured by Red Devil), colloid mill ("PUC colloid mill" manufactured by PUC, "colloid mill MK" manufactured by IKA), corn mill ("corn mill MKO" manufactured by IKA, etc.), ball mill, sand Media-type dispersers such as mills (such as Shinmaru Enterprises' ``Dino Mill''), art writers, pearl mills (such as Eirich's ``DCP mills''), coball mills, etc., wet jet mills (genus PY) '', Sugino Machine Co., Ltd. ``Starburst,'' Nanomizer Co., Ltd. ``Nanomizer, etc.), M Technic Co., Ltd. ``Clear SS-5'', Nara Mechanism Co., Ltd. ``MICROS,'' medialess dispersers, and other roll mills And the like, but are not limited thereto.

Next, a case of preparing a dispersion after surface treatment of carbon black with a dispersant by a dry treatment will be described. A carbon black dispersion can be obtained by adding and mixing a mixture of carbon black and a dispersant obtained by the following dry treatment into NMP. As a method of obtaining the carbon black surface-treated with a dispersant, a method by dry treatment may be mentioned.

In the dry treatment, the carbon black and the dispersant are mixed and pulverized by a dry treatment device at room temperature or under heating, while the dispersant is applied to the carbon black surface (adsorption). However, it is not necessary that the dispersant is completely adsorbed on the surface of the carbon black, and if it is homogeneously mixed to some extent, there may be no problem in practical use. The apparatus to be used is not particularly limited, and media type dispersers such as paint conditioners (manufactured by Red Devil), ball mills, art writers, vibration mills, kneaders, roller mills, stone mills, planetary mixers, Henschel mixers, Dispersing and kneading machines such as hybridizer (Nara Machinery Co., Ltd.), Mechano Micros (Nara Machinery Co., Ltd.), and Mechano Fusion System AMS (Hosokawa Micron Co., Ltd.) can be used, but contamination etc. Considering this, it is more preferable to use a medialess dispersion/kneader.

Further, at this time, an organic solvent may be added within a range in which the treated product does not become a gel. It is expected that the interaction between the carbon black and the dispersant is promoted by improving the wetting or (part) dissolution of the dispersant by the addition of the solvent and the wetting of the carbon black to the dispersant. The solvent used at this time is not particularly limited, but when using other than NMP, it is preferable to dry after treatment. In addition, the amount of the organic solvent added varies depending on the material to be used, but is 0.5 to 100% by weight based on the amount of the dispersant added. Further, by allowing nitrogen gas or the like to flow as needed, the inside of the dry treatment apparatus may be treated as a deoxygenated atmosphere.

The dry treatment time can be arbitrarily set according to the device to be used and the desired mixing degree. By performing these dry treatments, it is possible to obtain a powder or a bulk treated product. You may further dry and crush the obtained treated product after that.

In the case of the first invention (the dispersant is mainly polyvinyl alcohol alone), the amount of the dispersant added to carbon black is preferably 0.65 parts by weight or more and 15 parts by weight or less, and 0.65 parts by weight or more and 10 parts by weight based on 100 parts by weight of carbon black. The following are more preferable, 1 part by weight or more and 10 parts by weight or less are still more preferable, 1 part by weight or more and 8 parts by weight or less are still more preferable, and 2 parts by weight or more and 8 parts by weight or less are particularly preferable. Further, in the case of the second invention (the dispersant is a combination of polyvinyl alcohol and a pigment derivative), it is preferably 50 parts by weight or less, preferably 0.5 parts by weight or more and 40 parts by weight or less, and 0.5 parts by weight based on 100 parts by weight of carbon black. It is more preferably 20 parts by weight or less, more preferably 1 part by weight or more and 15 parts by weight or less, even more preferably 1 part by weight or more and 10 parts by weight or less, and particularly preferably 1 part by weight or more and 8 parts by weight or less. In the case of the third invention (the dispersant is mainly polyvinyl alcohol alone), more than 8 parts by weight and 40 parts by weight or less are preferable, more preferably more than 8 parts by weight and 30 parts by weight or less, based on 100 parts by weight of carbon black. More preferably more than 25 parts by weight or less, more preferably more than 8 parts by weight and 20 parts by weight or less, and particularly preferably more than 8 parts by weight and 15 parts by weight or less.

When the dispersant is a combination of polyvinyl alcohol and a pigment derivative, the amount of polyvinyl alcohol added as a dispersant to carbon black is preferably 0.1 parts by weight or more and 20 parts by weight or less, and 0.15 parts by weight or more and 10 parts by weight based on 100 parts by weight of carbon black. It is more preferably not more than 0.2 parts by weight, more preferably not more than 8 parts by weight, more preferably not less than 0.2 parts by weight and not more than 4 parts by weight, and particularly preferably not less than 0.4 parts by weight and not more than 4 parts by weight.

When the dispersant is a combination of polyvinyl alcohol and a pigment derivative, the ratio of polyvinyl alcohol in the dispersant is preferably 10 parts by weight or more and 90 parts by weight or less, and 20 parts by weight or more and 80 parts by weight or less based on 100 parts by weight of the dispersant. Is more preferable, and 25 parts by weight or more and 75 parts by weight or less are particularly preferable.

The amount of the dispersant to be added in the carbon black dispersion is determined by the specific surface area of the carbon black to be added, the average particle diameter after dispersion of the carbon black particles, and the amount of the dispersant adsorbed to the carbon black.

In particular, the amount of polyvinyl alcohol added to the specific surface area of carbon black is important, and when the saponification degree of polyvinyl alcohol is 50-95 mol% (preferably 60-85 mol%), the BET specific surface area of carbon black is X ㎡/g, when the addition amount of polyvinyl alcohol to 1 g of carbon black is aX g, a carbon black dispersion with high concentration, low viscosity and long-term storage stability can be prepared in the range of 0.00017 ≤ a ≤ 0.00256. It has been discovered that there is a critical range.

Further, from the viewpoint of obtaining good dispersion or battery characteristics, it is more preferably in the range of 0.00019≦a≦0.00217, more preferably in the range of 0.00026≦a≦0.00145, and particularly preferably in the range of 0.00051≦a≦0.00145.

By blending in the above ratio, it becomes possible to reduce the viscosity of the carbon black dispersion, and it becomes easy to obtain a dispersion liquid having a high concentration and excellent dispersibility and storage stability.

<Active material>

When the dispersion is used for the battery electrode mixture layer, a positive electrode active material or a negative electrode active material can be further contained.

Although it does not specifically limit as a positive electrode active material for lithium ion secondary batteries, Metal compounds, such as metal oxides, metal sulfides, etc. capable of doping or intercalating with lithium ions, and conductive polymers may be used. Examples thereof include oxides of transition metals such as Fe, Co, Ni, and Mn, complex oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, lithium such as transition metal oxide powder such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , and TiO ₂ , layered structure lithium nickel oxide, cobalt oxide, lithium manganate, spinel structure lithium manganate, etc. Composite oxide powders of transition metals, lithium iron phosphate-based materials which are phosphoric acid compounds having an olivine structure, and transition metal sulfide powders such as TiS ₂ and FeS. It is also possible to use conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene. Moreover, you may mix and use the said inorganic compound and organic compound.

The negative active material for a lithium ion secondary battery is not particularly limited as long as it is capable of doping or intercalating with lithium ions. For example, metal Li, alloys thereof such as tin alloy, silicon alloy, lead alloy, etc., Li _X Fe ₂ O ₃ , Li _X Fe ₃ O ₄ , Li _X WO ₂ , lithium titanate, lithium vanadate, silicic acid Metal oxides such as lithium, conductive polymers such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon or hard carbon, artificial graphite such as highly graphitized carbon materials, or natural graphite Carbonaceous materials, such as carbonaceous powder, carbon black, mesophase carbon black, resin-fired carbon material, base layer growth carbon fiber, and carbon fiber, are mentioned. These negative electrode active materials may be used alone or in combination.

These active materials preferably have an average particle diameter in the range of 0.05 to 100 µm, more preferably in the range of 0.1 to 50 µm. The average particle diameter of an active material in this specification is an average value of the particle diameters of an active material measured with an electron microscope.

In the third invention, the amount of polyvinyl alcohol added as a dispersant is preferably 0.05 parts by weight or more and less than 2 parts by weight, and 0.05 parts by weight or more with respect to 100 parts by weight of the total amount of solid components contained in the carbon black dispersion containing the electrode active material. It is more preferably less than 1.5 parts by weight, more preferably 0.05 parts by weight or more and less than 1.25 parts by weight, even more preferably 0.05 parts by weight or more and less than 1 part by weight, and particularly preferably 0.1 parts by weight or more and less than 1 part by weight.

<Other additives>

Conventionally known dispersants, resins, additives, and the like may be used in combination for the purpose of adjusting the properties of the coating film and the like within a range that does not interfere with the subject of the invention. Examples of such dispersants include polyvinyl acetal resins (polyvinyl butyral resins, etc.), polyvinylpyrrolidone resins, known dye derivatives, and low molecular weight surfactants. In addition, as resin, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene, polypropylene, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid , Polyacrylamide, polyurethane, polydimethylsiloxane, epoxy resin, acrylic resin, polyester resin, melamine resin, phenol resin, various rubbers such as styrene butadiene rubber, lignin, pectin, gelatin, xanthan gum, wellan gum, succino Glycans, cellulose resins, polyalkylene oxides, polyvinyl ethers, chitins, chitosans, starches, and the like. Further, examples of the additives include phosphorus compounds, sulfur compounds, organic acids, amine compounds, amide compounds, organic esters, various silane-based, titanium-based, and aluminum-based coupling agents. These conventionally known dispersants, resins, additives, and the like can be used alone or in combination of two or more.

<Use of carbon black dispersion>

The field of use of the carbon black dispersion is not particularly limited, but fields requiring shading, conductivity, durability, jet blackness, etc., such as gravure ink, offset ink, backcoat for magnetic recording media, electrostatic toner, inkjet, automotive paint, It is possible to provide a stable and uniform composition in a fiber/plastic forming material, an electrode for a battery, and a seamless belt for electrophotography. Among them, the use of NMP, the use of polyvinylidene fluoride or polyimide precursors, etc., and the strength and flexibility of the formed coating or molded product are good, so that the lithium ion secondary battery electrode, the electric double layer capacitor electrode, the lithium ion capacitor It is suitably used for electrode, electrophotographic seamless belt, etc.

Using a carbon black dispersion, and further adding a binder such as polyvinylidene fluoride and polytetrafluoroethylene, a lithium ion secondary battery electrode, an electrode for an electric double layer capacitor, a primer layer of an electrode for a lithium ion capacitor, and additionally cobalt Lithium transition metal complex oxides such as lithium acid and lithium manganate, graphite, activated carbon, graphite, positive electrode active materials such as carbon nanotubes or carbon nanofibers, or negative electrode active materials are added to provide lithium ion secondary battery electrodes, electric double layer capacitor electrodes, lithium An electrode layer of an electrode for an ion capacitor can be prepared. In addition, the seamless belt for electrophotography can be manufactured by a conventionally known method, using a carbon black dispersion as a conductive material, polyimide, polyamideimide, and the like, and precursors thereof as components.

<electrode>

An electrode can be obtained by forming a battery electrode mixture layer by coating and drying a positive electrode active material or a carbon black dispersion containing a negative electrode active material on a current collector.

(The current collector)

The material or shape of the current collector used for the electrode is not particularly limited, and one suitable for various secondary batteries can be appropriately selected. For example, the material of the current collector includes metals or alloys such as aluminum, copper, nickel, titanium, or stainless steel. Further, as the shape, generally a flat foil is used, but a roughened surface, a perforated foil, and a mesh-shaped current collector can also be used.

(Battery electrode mixture layer)

There is no restriction|limiting in particular as a method of coating a mixture slurry or a composition for forming an underlayer on the current collector, and a known method can be used. Specifically, a die coating method, a dip coating method, a roll coating method, a doctor coating method, a knife coating method, a spray coating method, a gravure coating method, a screen printing method or an electrostatic coating method may be mentioned. A blow dryer, a warm air dryer, an infrared heater, a far-infrared heater, etc. may be used, but the present invention is not particularly limited thereto.

Further, after application, a rolling treatment using a flat plate press or a calender roll may be performed. The thickness of the battery electrode mixture layer is generally 1 µm or more and 500 µm or less, and preferably 10 µm or more and 300 µm or less.

<Secondary battery>

A secondary battery can be obtained by using an electrode on at least one of the positive or negative electrode. As secondary batteries, in addition to lithium ion secondary batteries, sodium ion secondary batteries, magnesium secondary batteries, alkaline secondary batteries, lead acid batteries, sodium sulfur secondary batteries, lithium air secondary batteries, and the like are mentioned. An electrolyte solution, a separator, etc. can be used suitably.

(Electrolyte)

The case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, a lithium-containing electrolyte dissolved in a non-aqueous solvent is used. As an electrolyte, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₃ C, Lil, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN or LiBPh ₄ and the like, but are not limited thereto.

Although it does not specifically limit as a non-aqueous solvent, For example, carbonates, such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate; γ-butyrolactone, γ-valerolactone And lactones such as γ-octanoiclactone; tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1, Glymes such as 2-ethoxyethane and 1,2-dibutoxyethane; esters such as methyl formate, methyl acetate and methyl propionate; sulfoxides such as dimethyl sulfoxide and sulfolane; and acetonitrile Nitriles, such as, etc. are mentioned. Each of these solvents may be used alone, or two or more of them may be used in combination.

(Separator)

Examples of the separator include polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyamide nonwoven fabric, and those subjected to a hydrophilic treatment to these, but are not particularly limited thereto.

(Battery structure and configuration)

The structure of the lithium ion secondary battery is not particularly limited, but it is usually composed of a positive electrode, a negative electrode, and a separator installed as needed, and may have various shapes depending on the purpose of use, such as paper type, cylindrical shape, button type, and stack type.

Example

<Example according to the first invention>

The first invention will be mainly described in detail based on the examples below, but the following examples are not necessarily only related to the first invention, but also refer to examples of these inventions if they fall within the scope of the second invention or the third invention. I can. In addition, the present invention is not limited to the following examples unless the gist is exceeded. In this example, parts represent parts by weight, and% represents weight percent, respectively.

Carbon black (sometimes abbreviated as “CB”), polyvinyl alcohol (sometimes abbreviated as “PVA”), binders, and electrode active materials used in Examples and Comparative Examples are shown below. In addition, in each table, only the composition of each raw material is described, but the remaining components not specifically described are all N-methyl-2-pyrrolidone (NMP).

<Carbon Black>

• #30 (manufactured by Mitsubishi Chemical): Furnace black, average primary particle diameter of 30 nm, specific surface area of 74 m 2 /g. Hereinafter, it is abbreviated as #30.

-#5 (manufactured by Mitsubishi Chemical): Furnace black, average primary particle diameter of 76 nm, specific surface area of 29 m 2 /g. Hereinafter, it abbreviates as #5.

-MA77 (manufactured by Mitsubishi Chemical): Oxidation-treated carbon black, average primary particle diameter of 23 nm, specific surface area of 130 m 2 /g. Hereinafter, it abbreviates as MA77.

Denka Black HS-100 (manufactured by Denki Chemical Industries, Ltd.): Acetylene black, average primary particle diameter of 48 nm, specific surface area of 39 m 2 /g. Hereinafter, it is abbreviated as HS-100.

-Denka Black products (manufactured by Denki Kagaku Kogyo): Acetylene black, average primary particle diameter of 35 nm, specific surface area of 69 m 2 /g. Hereinafter, it is abbreviated as an incoming product.

EC-300J (manufactured by Arc Irradiation): Ketjen Black, an average primary particle diameter of 40 nm, a specific surface area of 800 m 2 /g. Hereinafter, it abbreviates as 300J.

(Measurement method of average primary particle diameter of carbon black)

The average primary particle diameter (MV) of carbon black was measured (calculated) by the method shown below. Propylene glycol monomethyl ether acetate was added to the carbon black powder, and a small amount of Disperbyk-161 was added as a resin-type dispersant, followed by dispersion treatment in a water bath of an ultrasonic cleaner for 1 minute to prepare a sample for measurement. This sample was applied to a target for measurement, dried, and photographed to observe the primary particles of 100 or more carbon blacks with a transmission electron microscope (transmission electron microscope H-7650 manufactured by Hitachi High Technologies). Select 100 random carbon black particles from the photographed image, and take the average value of the minor axis diameter and major axis diameter of the primary particles as the particle diameter (d), and then regard the individual carbon black as a sphere with the particle diameter (d) obtained. Then, the volume (V) of each particle was calculated|required, this operation|work was performed for 100 carbon black particles, and it calculated from it using the following formula (1).

Equation (1)　　　　　　MV=Σ(V·d)/Σ(V)

<Polyvinyl alcohol>

· Kuraray Poval L-8 (manufactured by Kuraray): Polyvinyl alcohol, saponification degree of 71 mol%, average polymerization degree of 1,000 or less, 4% aqueous solution viscosity of 5.5 mPa·s. Hereinafter, it is abbreviated as L-8.

-Kuraray Poval L-10 (manufactured by Kurare Corporation): Polyvinyl alcohol, saponification degree of 72 mol%, average polymerization degree of 1,000 or less. Hereinafter, it abbreviates as L-10.

Kuraray Poval C-506 (manufactured by Kuraray): Cationic modified polyvinyl alcohol, saponification degree of 76 mol%, average polymerization degree of 600, 4% aqueous solution viscosity of 5.1 mPa·s. Hereinafter, it abbreviates as C-506.

Kuraray Poval KL-506 (manufactured by Kuraray): Anion-modified polyvinyl alcohol, saponification degree of 77 mol%, average polymerization degree of 600, 4% aqueous solution viscosity of 5.6 mPa·s. Hereinafter, it abbreviates as KL-506.

Gosenol KL-05 (manufactured by Nippon Synthetic Chemical Industries, Ltd.): Polyvinyl alcohol, saponification degree 82 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 4.4 mPa·s. Hereinafter, it abbreviates as KL-05.

-Kuraray Poval PVA-205 (manufactured by Kuraray): Polyvinyl alcohol, saponification degree 88 mol%, average polymerization degree 500, 4% aqueous solution viscosity 5.0 mPa·s. Hereinafter, it abbreviates as PVA-205.

High-sefimer LL-02 (manufactured by Nippon Synthetic Chemical Co., Ltd.): Polyvinyl alcohol, saponification degree 50 mol%, average polymerization degree 1,000 or less, 4% aqueous solution viscosity 7.7 mPa·s. Hereinafter, it abbreviates as LL-02.

Synthetic product 1: Polyvinyl alcohol, saponification degree of 60 mol%, average polymerization degree of about 500, 4% aqueous solution viscosity of 5.2 mPa·s.

Synthetic product 2: Polyvinyl alcohol, saponification degree of 85 mol%, average polymerization degree of about 500, 4% aqueous solution viscosity 5.7 mPa·s.

Synthetic product 3: Polyvinyl alcohol, saponification degree of 72 mol%, average polymerization degree of about 100, 4% aqueous solution viscosity 2.0 mPa·s.

Synthetic product 4: Polyvinyl alcohol, saponification degree of 70 mol%, average polymerization degree of about 1,500, 4% aqueous solution viscosity of 19.8 mPa·s.

In addition, Synthesis 1, Synthesis 2, Synthesis 3, and Synthesis 4 are obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the art.

<Binder>

-KF polymer W1100 (manufactured by Kureha Corporation): Polyvinylidene fluoride (PVDF), hereinafter abbreviated as PVDF.

-KF polymer W7300 (manufactured by Kureha Corporation): Polyvinylidene fluoride (PVDF), hereinafter abbreviated as #7300.

<Active material>

HLC-22 (manufactured by Honjo Chemical): Positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle diameter of 6.6 µm, specific surface area of 0.62 m 2 /g. Hereinafter, it is abbreviated as LCO.

MCMB6-28 (manufactured by Osaka Gas Chemical): Mesophase carbon (MFC), a negative electrode active material, average particle diameter of 5 to 7 µm, specific surface area of 4 m 2 /g. Hereinafter, abbreviated as MFC.

<Evaluation of carbon black dispersion>

Evaluation of the carbon black dispersion obtained in Examples and Comparative Examples was performed by measuring the viscosity (storage stability thereof) and the average particle diameter after dispersion (the storage stability thereof).

Measurement of the viscosity value was performed immediately after sufficiently stirring the dispersion with a spatula at a dispersion temperature of 25° C. and a rotor rotation speed of 60 rpm using a B-type viscometer (manufactured by Toki Sangyo). The rotor used for the measurement is No. 1 when the viscosity value is less than 100 mPa·s, No. 2 when it is 100 or more and less than 500 mPa·s, and No. 3 when it is 500 or more and less than 2,000 mPa·s, and 2,000 or more. In the case of less than 10,000 mPa·s, those of No. 4 were used, respectively. When the obtained viscosity value was 10,000 mPa·s or more, it was described as ">10000", which indicates that the viscosity was so high that it was impossible to evaluate with the type B viscometer used for evaluation. The lower the viscosity, the better the dispersibility, and the higher the viscosity, the worse the dispersibility. The storage stability was evaluated from the change in the viscosity value after the carbon black dispersion was allowed to stand at 50° C. for 30 days and stored. The smaller the change, the better the stability.

In addition, for the measurement of the average particle diameter after dispersion, a solution subjected to ultrasonic treatment after diluting the carbon black dispersion to an appropriate concentration with NMP is used as a measurement sample, and a particle size distribution meter of the dynamic light scattering method (``Nanotrack UPA- EX” and a light source wavelength of 780 nm) were used to measure the average particle diameter (D50 value). Various measurement conditions are the loading index value of the dispersion solution diluted with NMP by the above method is 0.7 or more and 1.3 or less, the particle conditions are water absorbent particles, particle shape non-spherical, density 1.80, the solvent conditions are solvent refractive index 1.47, liquid temperature 20 ℃. The solvent viscosity was set at 1.80 mPa·s and the solvent viscosity at 25°C at a liquid temperature of 1.65 mPa·s, and the resulting median diameter was expressed as a D50 value. The measurement result was obtained by measuring a background value with respect to an NMP solvent at a liquid temperature of 25°C, and then filling a sample at a liquid temperature of 25°C prepared by the above method into a measuring container, and performing measurement under the above measurement conditions. When the same dispersion treatment is performed using the same carbon black, the smaller the D50 value, the better the dispersibility, and the larger the higher the dispersibility is. The storage stability was evaluated from the change in the D50 value after the carbon black dispersion was allowed to stand at 50°C for 30 days and stored. The smaller the change, the better the stability.

<Preparation of carbon black dispersion>

(Carbon black dispersion using polyvinyl alcohol with different degrees of saponification)

[Example 1-1 to Example 1-7]

According to the composition shown in Table 1-1, NMP and various polyvinyl alcohols were put in a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and a paint shaker was used with 1.25 mmØ zirconia beads as a medium. It dispersed over time to obtain each carbon black dispersion. All had low viscosity, small D50 values, and good storage stability. In addition, it became clear that the presence or absence of modification of polyvinyl alcohol does not significantly affect the performance as a dispersant.

[Comparative Example 1-1-Comparative Example 1-2]

According to the composition shown in Table 1-1, NMP and various polyvinyl alcohols were put in a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and a paint shaker was used with 1.25 mmØ zirconia beads as a medium. Disperse over time. However, all of the obtained dispersions are in a state of remarkably high viscosity, and the D50 value is large, indicating that the carbon black is not sufficiently dispersed. From this result, even if the a value calculated from the amount of polyvinyl alcohol added to the specific surface area of carbon black is within the range of 0.00017 ≤ a ≤ 0.00256, polyvinyl alcohol having a saponification degree of less than 60 mol% or more than 85 mol% In the case of use, it became clear that the intended high-concentration and low-viscosity carbon black dispersion could not be obtained.

(Dispersion of carbon black with different types and carbon black with different polyvinyl alcohol content)

[Example 1-8 to Example 1-24]

According to the composition shown in Table 1-1, NMP and polyvinyl alcohol were put in a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and 1.25 mmØ zirconia beads were used as a medium for 2 hours with a paint shaker. Disperse to obtain each carbon black dispersion. All had low viscosity, small D50 values, and good storage stability.

[Comparative Example 1-3, Reference Example 1-1]

According to the composition shown in Table 1-1, NMP and polyvinyl alcohol were put in a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and 1.25 mmØ zirconia beads were used as a medium for 2 hours with a paint shaker. Disperse to obtain each carbon black dispersion. All of the obtained dispersions were in a state of remarkably high viscosity, and the D50 value was large, so that the carbon black was not sufficiently dispersed. From this result, even if polyvinyl alcohol with a degree of saponification of 60 to 85 mol% is used, the a value calculated from the amount of polyvinyl alcohol added to the specific surface area of carbon black is outside the range of 0.00017 ≤ a ≤ 0.00256, It became clear that the carbon black dispersion liquid of high concentration and low viscosity could not be obtained.

<Preparation of a carbon black dispersion containing a binder>

[Example 2-1 to Example 2-16]

According to the composition shown in Table 1-2, NMP, various polyvinyl alcohols, and various binders were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and each carbon was dispersed for 1 hour with a homogenizer. A black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-17]

According to the composition shown in Table 1-2, NMP and polyvinyl alcohol were added to a glass bottle and sufficiently mixed and dissolved. Next, a powder mixture obtained by homogeneously mixing carbon black and PVDF was prepared, and this was added to the NMP solution of polyvinyl alcohol prepared in advance. After that, it was dispersed for 1 hour with a homogenizer to obtain a carbon black dispersion. It had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-18]

According to the composition shown in Table 1-2, 60 parts of the carbon black dispersion of Example 1-2, 6 parts of PVDF, and 34 parts of NMP were added to a glass bottle, and dispersed for 1 hour with a homogenizer to each carbon black dispersion. Got it. All had no coarse particles, had low viscosity, and had good storage stability.

[Comparative Example 2-1-Comparative Example 2-5]

According to the composition shown in Table 1-2, NMP, various polyvinyl alcohol and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and each carbon black was dispersed for 1 hour with a homogenizer. A dispersion was obtained. However, the viscosity of the obtained dispersion liquid was high as in the case where no binder was added, and it became clear that further improvement of the carbon black and binder concentration was impossible.

From Table 1-2, when a resin capable of dissolving or dispersing in NMP is used as a binder, the properties of the carbon black dispersion obtained are high concentration and low viscosity as in the case of preparing a dispersion without adding a binder of Table 1-1, and storage stability. It can also be seen that a good dispersion can be obtained.

<Preparation of a carbon black dispersion containing a positive electrode active material or a negative electrode active material>

[Example 3-1 to Example 3-3, Example 3-5 to Example 3-14]

According to the composition shown in Table 1-3, to the carbon black dispersion containing the binder obtained in Examples 2-1 to 2-3 and Examples 2-5 to 2-14, LCO as a positive electrode active material was added. And sufficiently mixed with a disper to obtain each liquid mixture. Since the carbon black dispersion liquid used was of low viscosity, a large amount of LCO could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Example 3-4]

After preparing a powder mixture obtained by homogeneously mixing 2.67 parts of the granular product, 1.33 parts of PVDF, 0.13 parts of L-8, and 62.7 parts of LCO, half of the total amount of the powder mixture was added to 33.17 parts of NMP. Treatment was performed for 30 minutes with a mixer. Next, half of the remaining powder mixture was added and treated with a planetary mixer for 30 minutes, and then all the remaining powder mixture was added and treated with a planetary mixer for 1 hour to obtain a carbon black dispersion containing LCO as a positive electrode active material. Got it. The obtained liquid was in a state of low viscosity as in the case of Example 3-2.

[Example 3-15 to Example 3-18]

According to the composition shown in Table 1-3, MFC, a negative electrode active material, was added to the carbon black dispersion containing the binders obtained in Examples 2-1 to 2-3 and 2-9, and sufficiently By mixing, each liquid mixture was obtained. Since the carbon black dispersion liquid used was of low viscosity, a large amount of MFC could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Comparative Example 3-1-Comparative Example 3-3]

According to the composition shown in Table 1-3, LCO as a positive electrode active material was added to the carbon black dispersion containing the binder obtained in Comparative Examples 2-3 to 2-5, and sufficiently mixed by a disper to obtain each mixed solution. . In all, since the viscosity value of the carbon black dispersion liquid used was high, the increase in the viscosity value when LCO was added was large compared to Examples 3-1 to 3-14, and the viscosity in the stability evaluation test The rise was also large.

[Comparative Example 3-4-Comparative Example 3-6]

According to the composition shown in Table 1-3, MFC as a negative electrode active material was added to the carbon black dispersion containing the binder obtained in Comparative Examples 2-3 to 2-5, and sufficiently mixed with a disper to obtain each mixed solution. . In all, since the viscosity value of the carbon black dispersion liquid used was high, the increase in the viscosity value when MFC was added was large compared to Examples 3-15 to 3-18, and the viscosity in the stability evaluation test The rise was also large.

<Production of battery electrode mixture layer>

Using the carbon black dispersion containing the positive electrode active material or the negative electrode active material obtained in each of the above Examples and Comparative Examples as a battery electrode mixture solution, coating on a polyethylene terephthalate (PET) film using a doctor blade, and then under reduced pressure 120 After drying at °C for 30 minutes, a coating film (battery electrode mixture layer) having a thickness of 100 μm was prepared.

The evaluation of the obtained battery electrode mixture layer was performed by the surface resistance and the appearance of the coating film. For the measurement of the surface resistance, it was measured according to JIS K7194 using Loresta-GP (manufactured by Mitsubishi Chemical Analysis).

The smaller the numerical value, the better the surface resistance. In addition, the appearance of the coating film was visually observed, and it was set as ○: no problem (good), △: spotted pattern (poor), and x: coarse particle line structure (very poor).

[Example 4-1 to Example 4-11, Comparative Example 4-1 to Comparative Example 4-3]

As the positive electrode mixture solution, a positive electrode using the battery electrode mixture solution obtained in Examples 3-1 to 3-3, Examples 3-5 to 3-12, and Comparative Example 3-1 to Comparative Example 3-3 A mixture layer (battery electrode mixture layer) was prepared. The evaluation results are shown in Table 1-4.

[Example 4-12 to Example 4-15, Comparative Example 4-4 to Comparative Example 4-5]

As the negative electrode mixture liquid, a negative electrode mixture layer (battery electrode mixture layer) was prepared using the battery electrode mixture liquid obtained in Examples 3-15 to 3-18 and Comparative Examples 3-4 to 3-5. The evaluation results are shown in Table 1-4.

From Table 1-4, the battery electrode mixture layers of Examples 4-1 to 4-15 have good coating appearance compared to the battery electrode mixture layers of Comparative Examples 4-1 to 4-5, and It became clear that the surface resistance was excellent. In Comparative Examples 4-1 to 4-5, coating was difficult because the viscosity of the electrode mixture solution used was too high, and as a result of the polyvinyl alcohol contained in a large amount functioning as an insulating component, the surface resistance value was considered to be increased. do.

<Assembly of a lithium ion secondary battery positive electrode evaluation cell>

[Example 5-1 to Example 5-11, Comparative Example 5-1 to Comparative Example 5-3]

The battery electrode mixture solution prepared previously (Example 3-1 to Example 3-3 and Example 3-5 to Example 3-12, Comparative Example 3-1 to Comparative Example 3-3 positive electrode mixture solution) was used as a current collector It was coated on an aluminum foil having a thickness of 20 μm to be formed using a doctor blade, heated and dried at 120° C. under reduced pressure, and rolled with a roller press to prepare a positive electrode mixture layer having a thickness of 100 μm. This was punched out with a diameter of 9 mm to form a working electrode, and a separator made of a porous polypropylene film (#2400 manufactured by Celgard) was inserted and laminated between the working electrode and the counter electrode using a metal lithium foil (thickness 0.15 mm) as a counter electrode. , A two-pole sealed metal cell (Hoseen HS flat cell) was filled with an electrolytic solution (a non-aqueous electrolytic solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent of 1: 1 of ethylene carbonate and diethyl carbonate). Assembled. The cell was assembled in an argon gas-substituted glove box.

<Assembly of a lithium ion secondary battery negative electrode evaluation cell>

[Examples 5-12 to 5-15, Comparative Example 5-4 to Comparative Example 5-5]

The previously prepared battery electrode mixture solution (Example 3-15 to Example 3-18, Comparative Example 3-4 to Comparative Example 3-5 negative electrode mixture solution) was applied to a doctor blade on an aluminum foil having a thickness of 20 μm to be a current collector. It was applied by using and heated and dried at 120° C. under reduced pressure, and then rolled with a roller press to prepare a negative electrode mixture layer having a thickness of 100 μm. This was punched out with a diameter of 9 mm to form a working electrode, and a separator made of a porous polypropylene film (#2400 manufactured by Celgard) was inserted and laminated between the working electrode and the counter electrode using a metal lithium foil (thickness 0.15 mm) as a counter electrode. , A two-pole sealed metal cell (Hoseen HS flat cell) was filled with an electrolytic solution (a non-aqueous electrolytic solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent of 1: 1 of ethylene carbonate and diethyl carbonate). Assembled. The cell was assembled in an argon gas-substituted glove box.

<Lithium ion secondary battery positive electrode characteristics evaluation>

Using a charging/discharging device (SM-8 manufactured by Hokuto Denko Co., Ltd.) at 25°C, the prepared positive electrode evaluation cell was charged with a constant current and constant voltage charging (upper limit voltage of 4.2 V) with a charging rate of 1.0 C. Charging and discharging was performed at a constant current of the same rate as the discharge to the lower limit voltage of 3.0 V as one cycle (charge and discharge interval pause time 30 minutes), and charge and discharge were performed by performing a total of 50 cycles. The cell after evaluation was disassembled in a glove box substituted with argon gas, and the appearance of the electrode coating film (appearance of the coating film after 50 cycles) was visually confirmed. The evaluation criteria for the appearance of the coating film are ○ (very good) when peeling from the current collector is not confirmed and there is no change in appearance at all, △ (good) when there is no peeling but change in appearance, partially from the current collector. The case where peeling of the composite material was confirmed was defined as x (defective). In addition, the capacity retention rate is a percentage of the discharge capacity at the 50th cycle to the discharge capacity at the first cycle, and the closer the value is to 100%, the better. The evaluation results are shown in Table 1-5.

<Lithium ion secondary battery negative electrode characteristics evaluation>

The prepared negative electrode evaluation cell was fully charged at 25°C using a charging/discharging device (SM-8 manufactured by Hokuto Denko Corporation) with a constant current constant voltage charging (upper limit voltage of 0.5 V) with a charging rate of 1.0 C, and at the same rate as when charging. Charge/discharge in which discharge is performed at a constant current until the voltage reaches 1.5 V was set as one cycle (charge and discharge interval pause time 30 minutes), and a total of 50 cycles were performed to perform charge/discharge cycles. The cell after evaluation was disassembled in a glove box substituted with argon gas, and the external appearance of the electrode coating film (appearance of the coating film after 50 cycles) was evaluated according to the same criteria as the positive electrode characteristic evaluation. The evaluation results are shown in Table 1-5.

From Table 1-5, Examples 5-1 to 5-11 and Examples 5-12 to 5-15 using the electrode of the present invention are Comparative Example 5-1 to Comparative Example 5-3 and Comparative Example. Compared with 5-4 to Comparative Example 5-5, the appearance of the coating film was good, and the result was good also about the capacity retention rate after 50 cycles.

From Table 1-5, it was found that in Examples 5-1 to 5-15, the coating film appearance was good and the capacity retention rate was also good even after 50 cycles of charge and discharge cycles. On the other hand, in Comparative Examples 5-1 to 5-5, since a good coating film could not be obtained, the positive electrode characteristics and the negative electrode characteristics could not be evaluated.

[Table 1-1]

[Table 1-2]

[Table 1-3]

[Table 1-4]

[Table 1-5]

<Example according to the second invention>

The second invention will be mainly described in detail based on the examples below, but the following examples are not necessarily only related to the second invention, but if they fall within the scope of the first invention or the third invention, reference will also be made to the examples of these inventions. I can. In addition, the present invention is not limited to the following examples unless the gist is exceeded. In this example, parts represent parts by weight, and% represents weight percent, respectively.

Carbon black used in Examples and Comparative Examples (sometimes abbreviated as ``CB''), polyvinyl alcohol (sometimes abbreviated as ``PVA''), organic pigment derivatives or triazine derivatives (abbreviated as ``pigment derivatives'') May be), a binder, an electrode active material, etc. are shown below. In addition, only the composition of each raw material is described in each table, but the rest of the components not specifically described are all N-methyl-2-pyrrolidone (NMP).

<Carbon Black>

Carbon black was the same as that used in the Example of the first invention. In addition, the average primary particle diameter of the carbon black was measured in the same manner as described in Examples of the first invention.

<Polyvinyl alcohol (resin containing formula A)>

-Kuraray Poval 　PVA-505 (made by Kuraray): Polyvinyl alcohol, saponification degree of 73 mol%, average polymerization degree of 500. Hereinafter, abbreviated as PVA-505.

-Kuraray Poval 　PVA-105 (manufactured by Kuraray): Polyvinyl alcohol, saponification degree of 98 mol%, average polymerization degree of 500. Hereinafter, abbreviated as PVA-105.

-Kuraray Poval LM-20 (manufactured by Kuraray): Polyvinyl alcohol, saponification degree of 40 mol%, average polymerization degree of 200. Or less, abbreviated as LM-20.

Synthetic product 1: Polyvinyl alcohol, saponification degree of 55 mol%, average polymerization degree of about 500.

Synthetic product 2: Polyvinyl alcohol, saponification degree of 60 mol%, average polymerization degree of about 500.

Synthetic product 3: Amino group modified polyvinyl alcohol, saponification degree of 76 mol%, modified group amount of 10 mol%, average polymerization degree of about 500.

Synthetic product 4: Polyvinyl alcohol, saponification degree of 85 mol%, average polymerization degree of about 500.

Synthetic product 5: Polyvinyl alcohol, saponification degree of 92 mol%, average polymerization degree of about 100.

Synthetic product 6: Polyvinyl alcohol, 72 mol% of saponification, and an average degree of polymerization of about 100.

Synthetic product 7: Polyvinyl alcohol, saponification degree of 70 mol%, average polymerization degree of about 1,500.

In addition, synthetic products 1 to 7 are obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the art.

<Polyvinyl Acetal>

•Srec BH-3 (manufactured by Sekisui Chemical): Polyvinyl butyral resin, hydroxyl group 34 mol%, butyralization degree 65 mol%, calculated molecular weight 110,000. Hereinafter, it abbreviates as BH-3.

S-REC KS-1 (manufactured by Sekisui Chemical): Polyvinyl acetoacetal resin, 25 mol% of hydroxyl groups, 74 mol% of acetalization, calculated molecular weight 27,000. Hereinafter, it abbreviates as KS-1.

-Vinilec H (manufactured by JNC): Polyvinyl formal resin, about 13 mol% of hydroxyl groups, and an average molecular weight of 73,000. Hereinafter, it is abbreviated as vinylec.

In addition, the hydroxyl group (mol%) contained in the polymer chain of polyvinyl acetal represents the molar ratio of the repeating unit represented by Formula A contained in the polymer chain of polyvinyl acetal.

<Acid pigment derivative>

The structure of the organic dye derivative having an acidic functional group is shown in Table 2-1.

[Table 2-1]

The structure of the triazine derivative having an acidic functional group is shown in Table 2-2.

[Table 2-2]

<Basic pigment derivative>

Table 2-3 shows the structure of an organic dye derivative having a basic functional group.

[Table 2-3]

The structure of the triazine derivative having a basic functional group is shown in Table 2-4.

[Table 2-4]

<Binder>

The binder used was the same as that used in the Example of the first invention.

<Other compounds>

1,2,3,4-benzenetetracarboxylic acid. Hereinafter, it is abbreviated as D-01.

<Active material>

HLC-22 (manufactured by Honjo Chemical): Positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle diameter of 6.6 µm, specific surface area of 0.62 m 2 /g. Hereinafter, it is abbreviated as LCO.

Artificial graphite: negative electrode active material, average particle diameter 18 µm. Hereinafter, abbreviated as graphite.

<Evaluation of carbon black dispersion>

Evaluation of the carbon black dispersion obtained in Examples and Comparative Examples was performed by measuring the viscosity (its storage stability) and the average particle diameter after dispersion (the storage stability) according to the method described in the first invention. However, the evaluation of the storage stability with respect to the viscosity was evaluated from the change in the viscosity value after the carbon black dispersion was allowed to stand at 60°C for 10 days and stored. The smaller the change, the better the stability. In addition, evaluation of the storage stability with respect to the average particle diameter after dispersion was evaluated from the change in the D50 value after the carbon black dispersion was allowed to stand at 60°C for 10 days and stored. The smaller the change, the better the stability.

<Preparation of carbon black dispersion by media dispersion>

(Carbon black dispersion using polyvinyl alcohol with different degrees of saponification)

[Example 1-1 to Example 1-3]

According to the composition shown in Table 2-5, NMP, various polyvinyl alcohol, and various pigment derivatives were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and 1.25 mmØ zirconia beads were used as a medium to paint. Each carbon black dispersion was obtained by dispersing for 2 hours with a conditioner. All had low viscosity, small D50 values, and good storage stability.

[Table 2-5]

<Preparation of a carbon black dispersion containing a binder>

(Carbon black dispersion using polyvinyl alcohol with different degrees of saponification)

[Example 2-1 to Example 2-8, Example 2-14 to Example 2-15]

According to the composition shown in Table 2-6, NMP, various polyvinyl alcohol, various pigment derivatives and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and dispersed for 1 hour with a homogenizer. Each carbon black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability. In addition, it became clear that the presence or absence of modification of polyvinyl alcohol does not significantly affect the performance as a dispersant.

[Example 2-16]

According to the composition shown in Table 2-6, NMP, polyvinyl alcohol and pigment derivatives were put in a glass bottle and sufficiently mixed and dissolved. Next, a powder mixture obtained by homogeneously mixing carbon black and PVDF was prepared, and this was added to the NMP solution of the dispersant prepared in advance. After that, it was dispersed for 1 hour with a homogenizer to obtain a carbon black dispersion. It had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-17 to Example 2-18]

According to the composition shown in Table 2-6, 65 parts of the carbon black dispersion of Example 1-2, 6 parts of PVDF or 3 parts of #7300, and 29 parts or 32 parts of NMP were added to a glass bottle, and a homogenizer Disperse for 1 hour to obtain each carbon black dispersion. All had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-19 to Example 2-20]

According to the composition shown in Table 2-6, NMP, polyvinyl alcohol, pigment derivative and #7300 were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and then dispersed for 1 hour with a homogenizer. A carbon black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability.

[Comparative Example 2-1-Comparative Example 2-10]

According to the composition shown in Table 2-6, NMP, various polyvinyl alcohol or various polyvinyl acetal resins, various pigment derivatives, and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, then carbon black was added, and homozygous Each carbon black dispersion was obtained by dispersing for 1 hour with a niger.

However, it became clear that the obtained dispersion liquid was in a state of high viscosity regardless of the kind of pigment derivative, and that further improvement of the carbon black and binder concentration was impossible.

In addition, in Comparative Example 2-1 to Comparative Example 2-2 and Comparative Example 2-6 to Comparative Example 2-7, all of them were in a state of remarkably high viscosity and the D50 value was large, indicating that carbon black was not sufficiently dispersed. there was. In addition, from these results, it is clear that the target high-concentration and low-viscosity carbon black dispersion cannot be obtained when polyvinyl alcohol and a pigment derivative having a saponification degree of less than 50 mol% or more than 95 mol% are combined and used as a dispersant. Became.

From Table 2-6, when a resin capable of dissolving or dispersing in NMP is used as a binder, the properties of the carbon black dispersion obtained are high concentration and low viscosity as in the case of preparing a dispersion without adding a binder in Table 2-5, and storage stability. It can also be seen that a good dispersion can be obtained.

(Carbon black dispersion using different types of carbon black)

[Example 2-9 to Example 2-13]

According to the composition shown in Table 2-6, NMP, polyvinyl alcohol, pigment derivative, and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and then dispersed for 1 hour with a homogenizer. A carbon black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability.

[Table 2-6]

(Carbon black dispersion using different types of pigment derivatives)

[Example 3-1 to Example 3-20]

According to the composition shown in Table 2-7, NMP, polyvinyl alcohol, various pigment derivatives, and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and then dispersed for 1 hour with a homogenizer. A carbon black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability. In addition, among these, it has been found that particularly good dispersions can be obtained when a triazine derivative is used.

[Comparative Example 3-1]

According to the composition shown in Table 2-7, NMP, polyvinyl alcohol, 1,2,3,4-benzenetetracarboxylic acid (D-01) and PVDF were added to a glass bottle and sufficiently mixed, dissolved or mixed and dispersed, Carbon black was added and dispersed for 1 hour with a homogenizer to obtain each carbon black dispersion. Since the obtained liquid was in a state of remarkably high viscosity and the D50 value was large, it was found that carbon black was not sufficiently dispersed.

[Table 2-7]

(Dispersion of carbon black with different polyvinyl alcohol content)

[Example 4-1 to Example 4-9]

According to the composition shown in Table 2-8, NMP, polyvinyl alcohol, various pigment derivatives, and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and then dispersed for 1 hour with a homogenizer. A carbon black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability.

[Comparative Example 4-1]

According to the composition shown in Table 2-8, NMP, polyvinyl alcohol, pigment derivatives, and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and each carbon was dispersed for 1 hour with a homogenizer. A black dispersion was obtained. Since the obtained liquid was in a state of remarkably high viscosity and the D50 value was large, it was found that carbon black was not sufficiently dispersed.

[Table 2-8]

<Preparation of a carbon black dispersion containing a positive electrode active material or a negative electrode active material>

[Example 5-1 to Example 5-23]

Depending on the composition shown in Table 2-9, Example 2-1 to Example 2-6, Example 2-11, Example 3-1, Example 3-6 to Example 3-10, Example 3- In the carbon black dispersions containing the binders obtained in 16 to Example 3-17, Example 4-1 to Example 4-7 and Example 4-9, LCO as a positive electrode active material was added, and sufficiently mixed by a disper. Each mixed solution was obtained. Since the carbon black dispersion liquid used was of low viscosity, a large amount of LCO could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Example 5-24]

According to the composition shown in Table 2-9, after preparing a powder mixture obtained by homogeneously mixing 2.7 parts of HS-100, 1.25 parts of PVDF, 0.011 parts of polyvinyl alcohol, 0.043 parts of pigment derivatives and 63 parts of LCO, , Half of the total amount of the powder mixture was added to 32.996 parts of NMP, and treatment was performed for 30 minutes with a planetary mixer. Next, half of the remaining powder mixture was added and treated with a planetary mixer for 30 minutes, and then all the remaining powder mixture was added and treated with a planetary mixer for 1 hour to obtain a carbon black dispersion containing LCO as a positive electrode active material. Got it. The obtained liquid was in a state of low viscosity as in the case of Example 5-23.

[Example 5-25 to Example 5-28]

According to the composition shown in Table 2-9, graphite as a negative electrode active material was added to the carbon black dispersion containing the binder obtained in Example 2-2 to Example 2-5, and sufficiently mixed by a disper to obtain each mixed solution. . Since the carbon black dispersion liquid used had a low viscosity, a large amount of graphite could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Comparative Example 5-1-Comparative Example 5-5]

According to the composition shown in Table 2-9, for the carbon black dispersion containing the binder obtained in Comparative Example 2-3, Comparative Example 2-5, Comparative Example 2-8, Comparative Example 2-10 and Comparative Example 4-1 LCO, which is a positive electrode active material, was added and sufficiently mixed with a disper to obtain each mixed solution. In all, since the viscosity value of the carbon black dispersion liquid used was high, the increase in the viscosity value when LCO was added was large compared to Examples 5-1 to 5-23, and the viscosity in the stability evaluation test The rise was also large.

[Comparative Example 5-6-Comparative Example 5-8]

According to the composition shown in Table 2-9, graphite as a negative electrode active material was added to the carbon black dispersion containing the binder obtained in Comparative Example 2-8, Comparative Example 2-10 and Comparative Example 4-1, and sufficiently By mixing, each liquid mixture was obtained. In all, since the viscosity value of the carbon black dispersion liquid used was high, the increase in the viscosity value when graphite was added was large compared with Examples 5-25 to Example 5-28, and the viscosity in the stability evaluation test The rise was also large.

[Table 2-9]

<Production of battery electrode mixture layer>

Using the carbon black dispersion liquid containing the positive electrode active material or negative electrode active material obtained in each of the above Examples and Comparative Examples as a battery electrode mixture solution, a battery electrode mixture layer was prepared according to the method described in the first invention, and its evaluation was performed. In addition, when the surface resistance is not measurable, it is assumed that there is no numerical value (-), and "Δ" in the appearance of the coating film means "there is a spot pattern".

[Example 6-1 to Example 6-21, Comparative Example 6-1 to Comparative Example 6-3]

As the positive electrode mixture solution, Examples 5-1 to 5-6, Examples 5-8 to 5-14, Examples 5-16 to 5-23, Comparative Example 5-2 and Comparative Example 5 A positive electrode mixture layer (battery electrode mixture layer) was prepared using the battery electrode mixture solution obtained in -4 to Comparative Example 5-5. The evaluation results are shown in Table 2-10.

[Example 6-22 to Example 6-24, Comparative Example 6-4 to Comparative Example 6-5]

As the negative electrode mixture solution, the battery electrode mixture solution obtained in Examples 5-25 to Example 5-26, Example 5-28, and Comparative Examples 5-7 to Comparative Example 5-8 was used, and the negative electrode mixture layer (battery electrode mixture Layer) was prepared. The evaluation results are shown in Table 2-10.

From Table 2-10, the battery electrode mixture layer of Examples 6-1 to 6-24 has a good coating appearance compared to the battery electrode mixture layer of Comparative Example 6-1 to Comparative Example 6-5, and the coating film It became clear that the surface resistance of was excellent. In Comparative Examples 6-1 to 6-5, coating is difficult because the viscosity of the electrode mixture solution used is too high, and in Comparative Examples 6-3 and 6-5, a dispersant contained in a large amount functions as an insulating component. As a result, it is considered that the surface resistance value has increased.

[Table 2-10]

<Assembly of a lithium ion secondary battery positive electrode evaluation cell>

[Example 7-1 to Example 7-21, Comparative Example 7-1 to Comparative Example 7-3]

The battery electrode mixture solution prepared above (Example 5-1 to Example 5-6, Example 5-8 to Example 5-14, Example 5-16 to Example 5-23, Comparative Example 5-2 and comparison) Using the positive electrode mixture solution of Examples 5-4 to Comparative Example 5-5), a positive electrode evaluation cell was assembled according to the method described in the first invention.

<Assembly of a lithium ion secondary battery negative electrode evaluation cell>

[Example 7-22 to Example 7-24, Comparative Example 7-4 to Comparative Example 7-5]

The method described in the first invention using the previously prepared battery electrode mixture solution (Example 5-25 to Example 5-26, Example 5-28, and Comparative Example 5-7 to the negative electrode mixture solution of Comparative Example 5-8) As a result, a cell for negative electrode evaluation was assembled. However, copper foil was used instead of aluminum foil as the current collector.

<Lithium ion secondary battery positive electrode characteristics evaluation>

Positive electrode characteristics were evaluated according to the method described in the first invention. However, the temperature of the positive electrode evaluation cell was set to 40°C instead of 25°C. When a normal charge/discharge curve was not obtained due to peeling of the coating film from the current collector or a short circuit, and the capacity could not be obtained, a numerical value (-) was taken. The evaluation results are shown in Table 2-11.

<Lithium ion secondary battery negative electrode characteristics evaluation>

The negative electrode characteristics were evaluated according to the method described in the first invention. However, the temperature of the negative electrode evaluation cell was set to 40°C instead of 25°C, and the upper limit voltage of constant current constant voltage charging was not set to 0.5 V, but the lower limit voltage was set to 0.5 V. The evaluation results are shown in Table 2-11.

From Table 2-11, Examples 7-1 to 7-21 and Examples 7-22 to 7-24 using the electrode of the present invention are Comparative Example 7-1 to Comparative Example 7-3 and Comparative Example Compared with 7-4 to Comparative Example 7-5, the appearance of the coating film was good, there was no peeling from the current collector, and the adhesion was also good. Moreover, it was a good result also about the capacity retention rate after 50 cycles.

From Table 2-11, it was found that in Examples 7-1 to 7-24, the coating film appearance was good and the capacity retention rate was also good even after 50 cycles of charge/discharge cycles. On the other hand, in Comparative Examples 7-1 to 7-5, since a good coating film could not be obtained, positive electrode characteristics and negative electrode characteristics could not be evaluated.

[Table 2-11]

<Example according to the third invention>

The third invention will be described in detail based on the following examples, but the following examples are not necessarily only related to the third invention, but can also be referred to as examples of these inventions if they fall within the scope of the first invention or the second invention. have. In addition, the present invention is not limited to the following examples unless the gist is exceeded. In this example, parts represent parts by weight, and% represents weight percent, respectively.

Carbon black (sometimes abbreviated as “CB”), polyvinyl alcohol (sometimes abbreviated as “PVA”), binders, and electrode active materials used in Examples and Comparative Examples are shown below. In addition, in each table, only the composition of each raw material is described, but the remaining components not specifically described are all N-methyl-2-pyrrolidone (NMP).

<Carbon Black>

#850 (manufactured by Mitsubishi Chemical): Furnace black, average primary particle diameter of 17 nm, specific surface area of 220 m 2 /g. Hereinafter, it abbreviates as #850.

* #2600 (manufactured by Mitsubishi Chemical): Furnace black, average primary particle diameter of 13 nm, specific surface area of 370 m 2 /g. Hereinafter, it abbreviates as #2600.

· Ketjen Black 　EC-300J (manufactured by Arc Irradiation): Hollow carbon black, an average primary particle diameter of 40 nm, a specific surface area of 800 m 2 /g. Hereinafter, it abbreviates as 300J.

-Ketjen Black 　EC-600JD (manufactured by Arc Irradiation): Hollow carbon black, average primary particle diameter of 34 nm, specific surface area of 1,270 m 2 /g. Hereinafter, it abbreviates as 600JD.

In addition, the average primary particle diameter of the carbon black was measured in the same manner as described in Examples of the first invention.

<Polyvinyl alcohol>

-Kuraray Poval 　PVA-505 (made by Kuraray): Polyvinyl alcohol, saponification degree of 73 mol%, average polymerization degree of 500. Hereinafter, abbreviated as PVA-505.

-Kuraray Poval 　PVA-205 (made by Kuraray): Polyvinyl alcohol, saponification degree of 88 mol%, average polymerization degree of 500. Hereinafter, abbreviated as PVA-205.

· High sefimer 　LL-02 (manufactured by Nippon Synthetic Chemicals Co., Ltd.): Polyvinyl alcohol, saponification degree 50 mol%, average polymerization degree 1,000 or less. Hereinafter, it abbreviates as LL-02.

Synthetic product 1: Polyvinyl alcohol, saponification degree of 60 mol%, average polymerization degree of about 500.

Synthetic product 2: Polyvinyl alcohol, saponification degree of 85 mol%, average polymerization degree of about 500.

Synthetic product 3: Polyvinyl alcohol, saponification degree of 72 mol%, average polymerization degree of about 100.

Synthetic product 4: Polyvinyl alcohol, saponification degree of 70 mol%, average polymerization degree of about 1,500.

In addition, Synthesis 1, Synthesis 2, Synthesis 3, and Synthesis 4 are obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the art.

<Binder>

The binder used was the same as that used in the Example of the first invention.

<Active material>

HLC-22 (manufactured by Honjo Chemical): Positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle diameter of 6.6 µm, specific surface area of 0.62 m 2 /g. Hereinafter, it is abbreviated as LCO.

Artificial graphite: negative electrode active material, average particle diameter of 12 µm. Hereinafter, abbreviated as graphite.

<Evaluation of carbon black dispersion>

Evaluation of the carbon black dispersion obtained in Examples and Comparative Examples was performed by measuring the viscosity (its storage stability) and the average particle diameter after dispersion (the storage stability) according to the method described in the first invention. However, the evaluation of the storage stability with respect to the viscosity was evaluated from the change in the viscosity value after the carbon black dispersion was left to stand at 60°C for 10 days or 50°C for 15 days. The smaller the change, the better the stability. In addition, evaluation of the storage stability with respect to the average particle diameter after dispersion was evaluated from the change in the D50 value after the carbon black dispersion was left standing at 60°C for 10 days or at 50°C for 15 days and stored. The smaller the change, the better the stability.

<Preparation of carbon black dispersion>

(Carbon black dispersion using polyvinyl alcohol with different degrees of saponification)

[Example 1-1 to Example 1-8]

According to the composition shown in Table 3-1, NMP and various polyvinyl alcohols were put in a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and a paint conditioner was used with 1.25 mmØ zirconia beads as a medium. It dispersed over time to obtain each carbon black dispersion. All had low viscosity, small D50 values, and good storage stability.

[Comparative Example 1-1 to Comparative Example 1-3, Reference Example 1-1]

According to the composition shown in Table 3-1, NMP and various polyvinyl alcohols were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, carbon black was added, and a paint conditioner was used for 2 hours using 1.25 mmØ zirconia beads as a medium. Dispersed. However, all of the obtained dispersions are in a state of remarkably high viscosity, and the D50 value is large, indicating that the carbon black is not sufficiently dispersed. From this result, it became clear that when polyvinyl alcohol having a saponification degree of less than 60 mol% or more than 85 mol% was used, a carbon black dispersion having a high concentration and a low viscosity of the objective could not be obtained. In addition, even when the amount of polyvinyl alcohol as a dispersant is very excessive or insufficient with respect to carbon black, it has become clear that a target carbon black dispersion having a high concentration and low viscosity cannot be obtained.

[Table 3-1]

<Preparation of a carbon black dispersion containing a binder>

[Example 2-1 to Example 2-15]

According to the composition shown in Table 3-2, NMP, various polyvinyl alcohols, and various binders were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, various carbon blacks were added, and each carbon was dispersed for 1 hour with a homogenizer. A black dispersion was obtained. All had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-16, Example 2-17]

According to the composition shown in Table 3-2, NMP, polyvinyl alcohol and PVDF were put in a glass bottle, and sufficiently mixed, dissolved or mixed and dispersed. Then, carbon black obtained by mixing #850 and 300J at a weight ratio of 1 to 1, or carbon black obtained by mixing 300J and 600JD at a weight ratio of 1 to 1, was added, and dispersed for 1 hour with a homogenizer to prepare each carbon black dispersion. Got it. All had no coarse particles, had low viscosity, and had good storage stability.

[Example 2-18]

According to the composition shown in Table 3-2, NMP and polyvinyl alcohol were added to a glass bottle and sufficiently mixed and dissolved. Next, a powder mixture obtained by homogeneously mixing carbon black and PVDF was prepared, and this was added to the NMP solution of polyvinyl alcohol prepared in advance. After that, it was dispersed for 1 hour with a homogenizer to obtain a carbon black dispersion. There were no coarse particles, and the viscosity was low, and the storage stability was also good.

[Example 2-19]

According to the composition shown in Table 3-2, 57 parts of the carbon black dispersion of Example 1-2, 6 parts of PVDF, and 37 parts of NMP were added to a glass bottle, and dispersed for 1 hour with a homogenizer to each carbon black dispersion. Got it. All had no coarse particles, had low viscosity, and had good storage stability.

[Comparative Example 2-1-Comparative Example 2-3, Reference Example 2-1]

According to the composition shown in Table 3-2, NMP, various polyvinyl alcohol and PVDF were added to a glass bottle, sufficiently mixed, dissolved or mixed and dispersed, then carbon black was added and dispersed for 1 hour with a homogenizer to disperse each carbon black dispersion. Got it. However, the viscosity of the obtained dispersion liquid was high as in the case where no binder was added, and it became clear that further improvement of the carbon black and binder concentration was impossible.

[Table 3-2]

From Table 3-2, when a resin capable of dissolving or dispersing in NMP is used as a binder, the properties of the carbon black dispersion obtained are high concentration and low viscosity as in the case of preparing a dispersion without adding a binder in Table 1, and storage stability is also good. It can be seen that a dispersion can be obtained.

<Preparation of a carbon black dispersion containing a positive electrode active material or a negative electrode active material>

[Example 3-1 to Example 3-14]

According to the composition shown in Table 3-3, LCO as a positive electrode active material was added to the carbon black dispersions containing the binders obtained in Examples 2-1 to 2-14, and sufficiently mixed with a disper to obtain each mixed solution. . Since the carbon black dispersion liquid used was of low viscosity, a large amount of LCO could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Example 3-15]

1.71 parts of the granular product, 2.56 parts of PVDF, 0.26 parts of PVA-505, 56.7 parts of LCO, and a homogeneously mixed powder mixture were prepared, and then half of the total amount of the powder mixture was added to 38.77 parts of NMP. Treatment was performed for 30 minutes with a rotary mixer. Next, half of the remaining powder mixture was added and treated with a planetary mixer for 30 minutes, and then all the remaining powder mixture was added and treated with a planetary mixer for 1 hour to obtain a carbon black dispersion containing LCO as a positive electrode active material. Got it. The obtained liquid was in a state of low viscosity as in the case of Example 3-2.

[Example 3-16 to Example 3-20]

According to the composition shown in Table 3-3, graphite as a negative electrode active material was added to the carbon black dispersion containing the binders obtained in Examples 2-1 to 2-4 and 2-7, and sufficiently By mixing, each liquid mixture was obtained. Since the carbon black dispersion liquid used had a low viscosity, a large amount of graphite could be added, and the obtained mixed liquid was also in a state of low viscosity.

[Comparative Example 3-1-Comparative Example 3-4]

According to the composition shown in Table 3-3, LCO as a positive electrode active material was added to the carbon black dispersion containing the binder obtained in Comparative Example 2-1 to Comparative Example 2-3, and Reference Example 2-1, and It mixed sufficiently to obtain each liquid mixture. In all, since the viscosity value of the carbon black dispersion liquid used was high, the increase in the viscosity value when LCO was added was large compared to Examples 3-1 to 3-14, and the viscosity was significantly higher.

[Comparative Example 3-5-Comparative Example 3-7]

According to the composition shown in Table 3-3, graphite as a negative electrode active material was added to the carbon black dispersion containing the binder obtained in Comparative Example 2-1 to Comparative Example 2-3, and sufficiently mixed with a disper to obtain each mixed solution. . In all, since the viscosity value of the carbon black dispersion liquid used was high, compared with Examples 3-16 to 3-20, the increase in the viscosity value when graphite was added was large, and the viscosity was significantly higher.

[Table 3-3]

<Production of battery electrode mixture layer>

Using the carbon black dispersion liquid containing the positive electrode active material or negative electrode active material obtained in each of the above Examples and Comparative Examples as a battery electrode mixture solution, a battery electrode mixture layer was prepared according to the method described in the first invention, and its evaluation was performed. In addition, "Δ" in the external appearance of the coating film means "there is a spot pattern", and when the external appearance of the coating film is remarkably poor and cannot be measured, a numerical value (-) was taken.

[Example 4-1 to Example 4-14, Comparative Example 4-1 to Comparative Example 4-3]

As the positive electrode mixture solution, a positive electrode mixture layer (battery electrode mixture layer) was prepared using the battery electrode mixture solution obtained in Examples 3-1 to 3-14 and Comparative Example 3-1 to Comparative Example 3-3. The evaluation results are shown in Table 3-4.

[Example 4-15 to Example 4-19, Comparative Example 4-4 to Comparative Example 4-6]

As the negative electrode mixture solution, a negative electrode mixture layer (battery electrode mixture layer) was prepared using the battery electrode mixture solution obtained in Examples 3-16 to 3-20 and Comparative Examples 3-5 to 3-7. The evaluation results are shown in Table 3-4.

[Table 3-4]

From Table 3-4, the battery electrode mixture layer of Example 4-1 to Example 4-19 has a better coating appearance compared to the battery electrode mixture layer of Comparative Example 4-1 to Comparative Example 4-6, and the coating film It became clear that the surface resistance of was excellent. In Comparative Examples 4-1 to 4-6, coating is difficult because the viscosity of the electrode mixture solution used is too high, and in Comparative Examples 4-3 and 4-6, polyvinyl alcohol contained in a large amount is an insulating component. As a result of functioning as, it is thought that the surface resistance value increased.

<Assembly of a lithium ion secondary battery positive electrode evaluation cell>

[Example 5-1 to Example 5-14, Comparative Example 5-1 to Comparative Example 5-3]

A cell for positive electrode evaluation according to the method described in the first invention using the previously prepared battery electrode mixture solution (Example 3-1 to Example 3-14 and Comparative Example 3-1 to Comparative Example 3-3 positive electrode mixture solution) Was assembled.

<Assembly of a lithium ion secondary battery negative electrode evaluation cell>

[Examples 5-15 to 5-19, Comparative Example 5-4 to Comparative Example 5-6]

A cell for negative electrode evaluation according to the method described in the first invention using the previously prepared battery electrode mixture solution (Example 3-16 to Example 3-20 and Comparative Example 3-5 to the negative electrode mixture solution of Comparative Example 3-7) Was assembled. However, copper foil was used instead of aluminum foil as the current collector.

<Lithium ion secondary battery positive electrode characteristics evaluation>

Positive electrode characteristics were evaluated according to the method described in the first invention. However, the temperature of the positive electrode evaluation cell was set to 15°C instead of 25°C. When a normal charge/discharge curve was not obtained due to peeling of the coating film from the current collector or a short circuit, and the capacity could not be obtained, a numerical value (-) was taken. The evaluation results are shown in Table 3-5.

<Lithium ion secondary battery negative electrode characteristics evaluation>

The negative electrode characteristics were evaluated according to the method described in the first invention. However, the temperature of the negative electrode evaluation cell was set to 15°C instead of 25°C, and the upper limit voltage for constant current constant voltage charging was set to 0.5V instead of 0.5V. The evaluation results are shown in Table 3-5.

[Table 3-5]

From Table 3-5, Examples 5-1 to 5-14 and Examples 5-15 to 5-19 using the electrode of the present invention are Comparative Example 5-1 to Comparative Example 5-3 and Comparative Example Compared with 5-4 to Comparative Example 5-6, it was found that the appearance of the coating film was good, there was no peeling off from the current collector, and the adhesion was also good. Moreover, it was a good result about the capacity retention rate after 50 cycles. On the other hand, in Comparative Examples 5-1 to 5-6, since a good coating film could not be obtained, the positive electrode characteristics and the negative electrode characteristics could not be evaluated.

Claims (18)

A carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and a solvent, wherein the solvent is N-methyl-2-pyrrolidone,
When the saponification degree of polyvinyl alcohol is 60 to 85 mol%, the BET specific surface area of carbon black is X ㎡/g, and the amount of polyvinyl alcohol added to 1 g of carbon black is aX g, a is 0.00017 ≤ a ≤ Carbon black dispersion, characterized in that the range of 0.00256, polyvinyl alcohol per 100 parts by weight of carbon black is 0.65 parts by weight or more and 15 parts by weight or less. A carbon black dispersion containing carbon black, polyvinyl alcohol and triazine derivatives or polyvinyl alcohol and organic dye derivatives as a dispersant, and a solvent, wherein the solvent is N-methyl-2-pyrrolidone,
Carbon black dispersion, characterized in that the total amount of the dispersant is 50 parts by weight or less with respect to 100 parts by weight of carbon black, and the polyvinyl alcohol contains 50 to 95 mol% of the repeating unit represented by the following formula (A) in the polymer chain.
[Formula A]

◈ Claim 3 was abandoned upon payment of the set registration fee. The method of claim 2,
Carbon black dispersion, characterized in that the dispersant is polyvinyl alcohol and a triazine derivative. ◈ Claim 4 was abandoned upon payment of the set registration fee. The method of claim 2,
Carbon black dispersion, characterized in that the polyvinyl alcohol contains 55 to 85 mol% of the repeating unit represented by Formula A in the polymer chain. ◈ Claim 5 was abandoned upon payment of the set registration fee. The method of claim 2,
Carbon black dispersion, characterized in that the total amount of the dispersant is 0.5 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of carbon black. The method of claim 2,
Carbon black dispersion, characterized in that the polyvinyl alcohol is 0.2 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of carbon black. ◈ Claim 7 was abandoned upon payment of the set registration fee. The method of claim 2,
Carbon black dispersion, characterized in that the polyvinyl alcohol is 0.2 parts by weight or more and 8 parts by weight or less based on 100 parts by weight of carbon black. A carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and a solvent, wherein the solvent is N-methyl-2-pyrrolidone,
The saponification degree of polyvinyl alcohol is 60-85 mol%, the BET specific surface area of carbon black is 30-1,500 ㎡/g, and the polyvinyl alcohol per 100 parts by weight of carbon black is more than 8 parts by weight and 40 parts by weight or less. Carbon black dispersion liquid. ◈ Claim 9 was abandoned upon payment of the set registration fee. The method of claim 8,
Carbon black dispersion, characterized in that the polyvinyl alcohol is more than 8 parts by weight and 25 parts by weight or less based on 100 parts by weight of carbon black. ◈ Claim 10 was abandoned upon payment of the set registration fee. The method according to claim 8 or 9,
Carbon black dispersion, characterized in that the BET specific surface area of the carbon black is 200 ~ 1,500 ㎡ / g. ◈ Claim 11 was abandoned upon payment of the set registration fee. The method according to claim 8 or 9,
Carbon black dispersion, characterized in that the BET specific surface area of the carbon black is 500 ~ 1,500 ㎡ / g. The method of claim 8,
Carbon black dispersion, characterized in that the carbon black is hollow carbon black. The method of claim 8,
Carbon black dispersion, characterized in that polyvinyl alcohol is 0.05 parts by weight or more and less than 2 parts by weight based on 100 parts by weight of the total amount of solid components contained in the dispersion. A carbon black dispersion for a battery comprising a positive electrode active material or a negative electrode active material in addition to the carbon black dispersion according to claim 1, 2 or 8. A battery electrode mixture layer obtained by applying the carbon black dispersion according to claim 1, 2 or 8. A battery electrode mixture layer obtained by applying the carbon black dispersion for batteries according to claim 14. A lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein at least one of the positive electrode and the negative electrode is a battery electrode according to claim 15 Lithium ion secondary battery comprising a mixture layer. A lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein at least one of the positive electrode and the negative electrode is a battery electrode according to claim 16 Lithium ion secondary battery comprising a mixture layer.