WO2014132809A1

WO2014132809A1 - Carbon black dispersion and use thereof

Info

Publication number: WO2014132809A1
Application number: PCT/JP2014/053403
Authority: WO
Inventors: 康平高橋; 真木　伸一郎; 尚久廣田; 昌洋寺澤
Original assignee: 東洋インキＳｃホールディングス株式会社; トーヨーカラー株式会社
Priority date: 2013-02-27
Filing date: 2014-02-14
Publication date: 2014-09-04

Abstract

Provided is a carbon black dispersion in which N-methyl-2-pyrrolidone that can achieve dispersibility at a lower viscosity and a higher concentration and can also achieve superior storage stability compared with conventional resin-type dispersants is used as a solvent. Also provided are: a battery electrode mix layer which is homogeneous and has good coating film properties and low surface resistance; and a lithium ion secondary battery equipped with the battery electrode mix layer. The problems can be solved by, for example, a carbon black dispersion comprising carbon black, polyvinyl alcohol (or a combination of polyvinyl alcohol with a pigment derivative) that serves as a dispersant, and N-methyl-2-pyrrolidone that serves as a solvent, said carbon black dispersion being characterized in that the degree of saponification of polyvinyl alcohol is 60 to 85 mol% and the value (a) falls within the range from 0.00017 to 0.00256 inclusive wherein X (m²/g) represents the BET specific surface area of carbon black and aX (g) represents the addition amount of polyvinyl alcohol relative to 1 g of carbon black.

Description

Carbon black dispersion and use thereof

The present invention relates to a carbon black dispersion excellent in dispersibility and storage stability. The present invention 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 additive, but when forming a battery electrode mixture layer, in order to shorten the production process in an efficient manner, the carbon black can be increased in a solvent. It is important to make it possible to easily disperse in concentration and uniformly.

In recent years, especially in consideration of the environment and production costs, the amount of solvent used and the energy used during drying have been reduced by producing a carbon black dispersion with a higher concentration and uniformity than before. It is requested to do.

These requirements have a great influence on the cost of the solvent and the energy used during drying. Therefore, the more expensive the solvent used or the higher the solvent used, the more important. N-methyl-2-pyrrolidone used in non-aqueous secondary batteries is more expensive than common solvents and has a very high boiling point of 200 ° C. or higher. Since energy is required, reduction of the amount of solvent used in the dispersion is strongly demanded.

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 so that the dispersion is in a stable state. Carbon using various dispersants Black dispersions have been proposed.

For example, in Patent Documents 1 and 2, carbon black is dispersed while adsorbing an acidic or basic organic dye derivative to the carbon black, thereby achieving dispersion stabilization without impairing the conductivity of the carbon black. A battery composition is described. However, when a carbon black dispersion liquid containing an electrode active material (hereinafter referred to as an electrode mixture liquid) obtained using an organic pigment derivative as a dispersant is applied to a coating film substrate, the electrode mixture layer and the coating layer are coated. In some cases, the adhesion of the film substrate may be insufficient, and the electrode mixture layer may unintentionally peel from the coating film substrate.

In order to solve the adhesion problem, for example, in Patent Document 3, as a dispersant for dispersing carbon black, a pigment derivative type dispersant and a polymer polymer type dispersant (hereinafter referred to as a resin type dispersant) are used. It is described that, when used in combination, a positive electrode plate having good adhesion can be produced while utilizing the performance as a dispersant possessed by the pigment derivative type dispersant. In particular, when using an oxazine derivative as a pigment derivative-type dispersant and polyvinyl butyral as a resin-type dispersant in combination in a specific ratio range, it is described that the balance between the viscosity and adhesion of the positive electrode mixture liquid can be achieved. Has been.

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

When polymers that are easily soluble in non-aqueous electrolytes such as polyvinyl acetal are used as dispersants, depending on the type and composition of the non-aqueous electrolyte used in the secondary battery, the resistance of the dispersant to non-aqueous electrolytes Is not sufficient, and there is a concern that the properties of the coating film will not be stable. Therefore, the resistance to non-aqueous electrolyte is higher, the coating film properties of the resulting coating film are stable, and in a N-methyl-2-pyrrolidone solvent. There has been a demand for the development of a resin-type dispersant having more excellent ability as a dispersant.

On the other hand, Patent Documents 5 and 6 describe coating liquids containing carbon black, unmodified or modified polyvinyl alcohol, and N-methyl-2-pyrrolidone, and Patent Document 5 describes this coating liquid. It describes that a positive electrode active material or a negative electrode active material is added to a working solution to produce an electrode plate of a lithium ion secondary battery. However, the polyvinyl alcohols in Patent Documents 5 and 6 are used in large amounts as binders (resin binders), and there is no technical idea of using polyvinyl alcohols as a dispersant.

Patent Documents 3 and 4 suggest the possibility of using polyvinyl alcohol as one of the dispersants and N-methyl-2-pyrrolidone as one of the solvents. However, although the physical and chemical properties of the carbon black, solvent type, and dispersant used are closely related to each other, what kind of physical properties are required when a specific solvent called N-methyl-2-pyrrolidone is used. However, no mention is made as to whether polyvinyl alcohols having chemical properties can function well as a dispersant, and the molecular structure, functional group ratio, The relationship between molecular weight and the conditions for functioning as a resin-type dispersant was still unclear.

General fully saponified polyvinyl alcohol is insoluble in N-methyl-2-pyrrolidone, does not function as a dispersant, and also applies to polyvinyl esters such as polyvinyl acetate as a precursor material. The inventors have found that it does not function well as a dispersant.

In general, when carbon black is dispersed using a dispersant, the dispersibility of the carbon black is deteriorated when the amount of the dispersant is extremely reduced, and on the contrary, the dispersibility is improved when the amount of the dispersant is extremely increased. However, when used in battery applications, the resin-type dispersant does not have sufficient resistance to the non-aqueous electrolyte, and the dispersant functions as an insulating component, resulting in a high resistance value and poor conductivity. It is expected to have a negative effect on battery characteristics.

However, in order to obtain a highly concentrated and uniformly dispersed carbon black dispersion, not only the physical and chemical properties of the carbon black used, the solvent type, and the dispersant, but also their quantitative relationships have been studied in detail. No examples have been reported. When N-methyl-2-pyrrolidone is used as a specific solvent and polyvinyl alcohols are mainly used as a dispersant, or N-methyl-2-pyrrolidone is used as a specific solvent, and polyvinyl alcohols and pigment derivatives ( When using organic dye derivatives or triazine derivatives), the physical and chemical properties of carbon black and the dispersant, and their quantitative relationship, are determined by the carbon black dispersion, the battery electrode mixture layer, and the battery characteristics. The actual situation is that no consideration has been given to how the impact is affected.

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

In general, when manufacturing an electrode for a lithium ion secondary battery, the solvent used for preparing the electrode mixture liquid is determined by the polymer material used for the binder in the battery. Currently, in the production of electrodes for lithium ion secondary batteries, polyvinylidene fluoride is generally used as a particularly suitable binder for forming an electrode, and N-methyl-2-pyrrolidone is generally used as a solvent for dissolving polyvinylidene fluoride. It is used. Since N-methyl-2-pyrrolidone has a very high boiling point of 202 ° C., it is necessary to spend a large amount of energy and time for drying the electrode mixture liquid. In order to solve this problem, attempts have been made to obtain an electrode mixture solution having a concentration as high as possible using N-methyl-2-pyrrolidone as a solvent. Another performance required for the carbon black dispersion liquid for the electrode mixture liquid of the lithium ion secondary battery is that it is desirable that the amount of the dispersant added is as small as possible. This is because the ratio of the other electrode constituent components in the electrode film decreases by the amount of the dispersant added.

International Publication No. 2008/108360 JP 2009-26744 A JP 2013-89485 A JP 2011-70908 A International Publication No. 2009/147789 International Publication No. 2011/024799

In view of the above situation, in the present invention, the resulting carbon black dispersion is significantly reduced in viscosity compared to conventionally known resin-type dispersants, that is, the carbon black concentration that can be achieved is significantly higher, and carbon It is an object to provide a carbon black dispersion using N-methyl-2-pyrrolidone as a solvent, which is excellent in black dispersibility and storage stability of the dispersion. Moreover, it is a subject to provide the battery electrode compound-material layer which has a uniform and favorable coating-film physical property and low surface resistance. Furthermore, it is a problem to provide a battery electrode mixture layer having uniform and good coating film properties and low surface resistance, and having good and stable coating film properties with good resistance of the resin-type dispersant to the non-aqueous electrolyte. It is.

(1) 1st invention The present inventors paid attention to the physical and chemical properties of carbon black, solvent species, and a dispersant, and as a result of examining the quantitative relationship thereof in detail, the specific surface area of carbon black was determined. And a use amount of polyvinyl alcohol having a specific degree of saponification, there is a critical range that greatly contributes to dispersibility, and when these are within a certain range, high concentration, low viscosity, and long-term It has been found that a carbon black dispersion having good 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, wherein the saponification degree of polyvinyl alcohol is When the BET specific surface area of carbon black is Xm ² / g and the amount of polyvinyl alcohol added to 1 g of carbon black is aXg, a is in the range of 0.00017 ≦ a ≦ 0.00256. The present invention relates to a carbon black dispersion.

Further, an embodiment of the present invention relates to the above carbon black dispersion, wherein the polyvinyl alcohol is from 0.65 parts by weight to 15 parts by weight with respect to 100 parts by weight of the carbon black.

Further, an embodiment of the present invention relates to the carbon black dispersion, wherein the polyvinyl alcohol is 2 to 8 parts by weight with respect to 100 parts by weight of the carbon black.

Further, an embodiment of the present invention relates to a carbon black dispersion for a battery, which further contains a positive electrode active material or a negative electrode active material in the carbon black dispersion.

Also, 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.

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. And at least one of a positive electrode and a negative electrode is related with the lithium ion secondary battery which comprises the said battery electrode compound-material layer.

(2) Second invention Further, the present inventors paid attention to the physical and chemical properties of carbon black, solvent species, and a dispersant, and as a result of detailed examination of their quantitative relationship, A critical contribution greatly contributing to dispersibility between the organic dye derivative or the triazine derivative and the amount of polyvinyl alcohol having a repeating unit represented by the following general formula (A) in a specific ratio in the polymer chain A carbon black dispersion having a high concentration, a low viscosity, and a good long-term storage stability when these are within a certain range, and having a low surface resistance, The present inventors have found that a battery electrode mixture layer having good resistance to a non-aqueous electrolyte can be obtained, and have completed the present invention.

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

Further, an embodiment of the present invention is a carbon black dispersion comprising carbon black, polyvinyl alcohol and a triazine derivative or polyvinyl alcohol and an organic dye derivative as a dispersant, and N-methyl-2-pyrrolidone as a solvent. Liquid,
When the total amount of the dispersant with respect to 100 parts by weight of carbon black is 50 parts by weight or less, the BET specific surface area of carbon black is Xm ² / g, and the amount of polyvinyl alcohol added to 1 g of carbon black is aXg. 0.00000 ≦ a ≦ 0.00256, and the polyvinyl alcohol contains 50 to 95 mol%, preferably 60 to 85 mol%, of the repeating unit represented by the general formula (A) in the polymer chain. And a carbon black dispersion.

Also, an embodiment of the present invention relates to the above carbon black dispersion, wherein the dispersant is polyvinyl alcohol and a triazine derivative.

An embodiment of the present invention also relates to the carbon black dispersion, wherein the polyvinyl alcohol contains 55 to 85 mol% of a repeating unit represented by the general formula (A) in a polymer chain. .

In addition, an embodiment of the present invention relates to the above carbon black dispersion, wherein the total amount of the dispersant with respect to 100 parts by weight of carbon black is 0.5 part by weight or more and 40 parts by weight or less.

Further, an embodiment of the present invention relates to the above carbon black dispersion, wherein the polyvinyl alcohol is from 0.2 parts by weight to 20 parts by weight with respect to 100 parts by weight of the carbon black.

Further, an embodiment of the present invention relates to the above carbon black dispersion, wherein the polyvinyl alcohol is from 0.2 parts by weight to 8 parts by weight with respect to 100 parts by weight of the carbon black.

(3) Third invention Further, the present inventors paid attention to the physical and chemical properties of carbon black, solvent species, and a dispersant, and as a result of detailed examination of their quantitative relationship, It is found that there is a critical range that greatly contributes to dispersibility between the specific surface area and the amount of polyvinyl alcohol having a specific degree of saponification, and when these are within a certain range, high concentration, low viscosity, And it discovered that the carbon black dispersion liquid with favorable long-term storage stability could be manufactured, and came to completion of this invention.

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, wherein the saponification degree of polyvinyl alcohol is 60 to 85 mol%, the BET specific surface area of carbon black is 30 to 1500 m ² / g, and the polyvinyl alcohol with respect to 100 parts by weight of carbon black is more than 8 parts by weight and 40 parts by weight or less, It relates to a carbon black dispersion.

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

An embodiment of the present invention also relates to the carbon black dispersion, wherein the carbon black has a BET specific surface area of 200 to 1500 m ² / g.

In addition, an embodiment of the present invention relates to the carbon black dispersion, wherein the carbon black has a BET specific surface area of 500 to 1500 m ² / g.

Further, an embodiment of the present invention relates to the carbon black dispersion, wherein the carbon black is a hollow carbon black.

The embodiment of the present invention is characterized in that the content of polyvinyl alcohol is 0.05 parts by weight or more and less than 2 parts by weight with respect to 100 parts by weight of the total solid components contained in the dispersion liquid. It relates to a carbon black dispersion.

According to the first and third inventions, it is possible to obtain a carbon black dispersion having a significantly lower viscosity than when a conventionally known resin-type dispersant is used, and to increase the carbon black concentration. Become.

According to the second invention, it is possible to obtain a coating film having better adhesion to the coating substrate than when a conventionally known pigment derivative type dispersing agent is used alone, and a conventionally known resin type dispersing agent A carbon black dispersion having a remarkably low viscosity can be obtained as compared with the case where it is used alone or in combination with a pigment derivative, and the carbon black concentration can be increased while maintaining adhesion.

Furthermore, according to the first invention, the second invention, and the third invention, it becomes possible to provide a carbon black dispersion having a higher concentration than before, and the amount of N-methyl-2-pyrrolidone solvent used is greatly reduced. In addition, the drying process of the coated film can be greatly shortened. Further, it is possible to provide a carbon black dispersion liquid using N-methyl-2-pyrrolidone as a solvent, which is excellent in carbon black dispersibility and dispersion storage stability.
In addition, when an electrode mixture solution for a secondary battery is prepared using the dispersion, it is easy to add and knead electrode active material powder because of its low viscosity, and each electrode component has a high concentration. Even when an electrode mixture solution is used, a uniform and good coating film can be obtained, and therefore a battery electrode mixture layer having a low surface resistance value can be obtained. Furthermore, when a battery electrode mixture layer is produced using the dispersion, it becomes possible to obtain a battery electrode mixture layer with good resistance to non-aqueous electrolyte and more stable coating film properties.

Hereinafter, the details of the present invention (first invention, second invention and third invention) will be described. In this specification, “carbon black dispersion” and “carbon black dispersion for battery” are referred to as “dispersion”, “organic dye derivative or triazine derivative” as “pigment derivative”, “polyvinyl alcohol” (first (Invention and third invention) or “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, various types such as commercially available hollow carbon black, furnace black, channel black, thermal black, acetylene black, ketjen black, etc., and commonly used oxidized carbon black, graphitized treatment Carbon black, carbon nanotubes and carbon nanofibers can also be used. Moreover, carbon black which has high electroconductivity, such as acetylene black and furnace black, and is produced industrially is used suitably.

The oxidation treatment of carbon black is performed by treating the carbon black at a high temperature in the air or by treating it with nitric acid, nitrogen dioxide, ozone, etc., for example, phenol group, quinone group, carboxyl group, carbonyl group. This is a treatment for directly introducing (covalently bonding) such an oxygen-containing polar functional group to the surface of carbon black, and is generally performed to improve the dispersibility of carbon black.

The average primary particle diameter of the carbon black used for the production of the dispersion is preferably 0.01 to 1 μm, particularly in the range of the average primary particle diameter of the carbon black used for general dispersions and paints. Is preferably 0.2 μm, more preferably 0.01 μm to 0.1 μm. The average primary particle size referred to here indicates an arithmetic average particle size measured with an electron microscope, and this physical property value is generally used to represent the physical characteristics of carbon black.

BET specific surface area and pH are known as other physical property values representing the physical characteristics of carbon black. The BET specific surface area refers to a specific surface area (hereinafter simply referred to as a specific surface area) measured by the BET method by nitrogen adsorption, and this specific surface area corresponds to the surface area of carbon black. The amount you need also increases. The pH changes under the influence of functional groups on the carbon black surface and impurities contained therein.

The carbon black used in the first and second inventions preferably has a BET specific surface area of 20 to 1500 m ² / g, more preferably 20 to 1000 m ² / g, and more preferably 20 to 500 m ² / g. preferably, more preferably those of 20 ~ 250m ² / g, more preferably those of 30 ~ 150m ² / g, particularly preferably from 30 ~ ^75m 2 / g. As long as the carbon black has the BET specific surface area, various commercially available products and synthetic products can be used alone, or two or more carbon blacks can be used in combination.

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 is high such as acetylene black, furnace black, hollow carbon black and graphitized carbon black. Carbon black having electrical conductivity and industrially produced is preferably used. Among these carbon blacks, acetylene black is particularly preferably used. Examples of acetylene black include Denka Black (manufactured by Denki Kagaku Kogyo Co., Ltd.), and various grades can be obtained as commercial products.

The carbon black used in the third invention preferably has a BET specific surface area of 30 to 1500 m ² / g, more preferably 200 to 1500 m ² / g, still more preferably 500 to 1500 m ² / g, Particularly preferred are those of up to 1000 m ² / g. As long as the carbon black has the BET specific surface area, various commercially available products and synthetic products can be used alone, or two or more carbon blacks can be used in combination.

Further, the BET specific surface area of the carbon black prepared by mixing two or more kinds of carbon black, the BET specific surface area of a carbon black i S _i, a certain percentage of carbon black i is in the total carbon black G _i As the sum of the product of the BET specific surface area of each carbon black type and the ratio, it can be calculated based on the following formula.
(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 having a BET specific surface area of 800 m ² / g and carbon black of 1200 m ² / g in a weight ratio of 1: 1 is 1000 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 and graphitized carbon black. Carbon black produced and industrially produced is preferably used. Among these carbon blacks, hollow carbon black having excellent conductivity per weight is particularly preferably used. Examples of the hollow carbon black include ketjen black (manufactured by Akzo Corporation), and various grades can be obtained as commercial products.

<Polyvinyl alcohol>
Polyvinyl alcohol is used as a dispersant. That is, polyvinyl alcohol is used as a dispersant rather than as a binder. Although there is no restriction | limiting in particular about the manufacturing method of polyvinyl alcohol, Hereinafter, polyvinyl alcohol obtained by using polyvinyl acetate as a raw material and saponifying this is described.

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

The saponification degree is the same as the definition of saponification degree known in the industry, and is based on the total number of moles of structural units (typically vinyl ester units) and vinyl alcohol units that can be converted into vinyl alcohol units by saponification. The ratio (mol%) occupied by the number of moles of the vinyl alcohol unit (in other words, the ratio (mol%) of the repeating unit represented by the general formula (A) contained in the 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 the 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. Mean value.

As polyvinyl alcohol, polyvinyl alcohol, particularly those obtained by saponifying polyvinyl acetate, are mainly used, but are not limited thereto. The saponification degree 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 it is the polyvinyl alcohol of the said saponification degree, various commercial products and synthetic products can be used individually or in combination of 2 or more types.

In addition, within the above saponification degree range, as a functional group other than a hydroxyl group and an acetic acid group, for example, an acetoacetyl group, a sulfonic acid group, a carboxyl group, a carbonyl group, an amino group, an isocyanate group introduced, Modified with various salts, other anion or cation modified, unsaturated modified, acetal modified (butyral modified, acetoacetal modified, formal modified, etc.) with aldehydes, diol structure introduced These are also included in the range of usable polyvinyl alcohol, and these can be used alone or in combination of two or more.

The polyvinyl alcohol preferably has an average degree of polymerization of 50 to 4000, then preferably 50 to 3000, more preferably 100 to 3000, particularly preferably 100 to 2000, and particularly preferably 100 to 1500. Further preferred. If it is polyvinyl alcohol of the said polymerization degree, various commercial products and synthetic products can be used individually or in combination of 2 or more types.

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

Those having a saponification degree of less than 50 mol% to 60 mol% have very good solubility in NMP, but are considered to be ineffective for dispersion due to poor adsorptivity to carbon black. Those larger than 95 mol% hardly dissolve or swell in NMP, so even if adsorbed to carbon black, the polymer chain cannot be extended to the NMP side, and therefore, the steric repulsion cannot be effectively performed. Inferred. On the other hand, those having a saponification degree within these ranges have a good balance between the solubility or swelling in NMP and the adsorptivity to carbon black and the steric repulsion effect after adsorption. It is considered to function particularly effectively.

Examples of commercially available polyvinyl alcohols included in the saponification degree range include Kuraray Poval (polyvinyl alcohol manufactured by Kuraray Co., Ltd.), Gohsenol (polyvinyl alcohol manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.), Denkapoval (manufactured by Denki Kagaku Kogyo Co., Ltd.), -Various grades can be obtained from the market under trade names such as POVAL (manufactured by Nippon Vinegar-Poval).

More specifically, Kuraray Poval's PVA-403 (saponification degree: 78.5 to 81.5 mol%, average polymerization degree: 300, viscosity of 4% aqueous solution at a liquid temperature of 20 ° C. according to JIS K6726: 2.8 to 3.3 mPa · s) s), 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 1000 or less, 4% aqueous solution viscosity 5.0 to 5.8 mPa · s), L-9 (saponification degree 69.5 to 72.5 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 6 0.0-6.5 mPa · s), L-9-78 (degree of saponification 76.5-79.0 mol%, average degree of polymerization 1000 or less, 4% aqueous solution viscosity 6.0-6.7 mPa · s), L- 10 (saponification degree 71.5 ~ 3.5 mol%, average polymerization degree 1000 or less), C-506 (saponification degree 74.0-79.0 mol%, average polymerization degree 600, 4% aqueous solution viscosity 4.0-6.0 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), Gohsenol KL-03 (saponification degree 78.5 to 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 1000 or less, 4% aqueous solution viscosity 4.0 to 5.0 mPa · s), NK-05R (71.0-75.0 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 4.5-5.5 mPa · s), KP-08R (71.0 ~ 73.5 mol%, average polymerization 1000, 4% although aqueous viscosity 6.0 ~ 8.0mPa · s), and the like, but is not limited thereto.

<N-methyl-2-pyrrolidone>
NMP is used for manufacturing electrodes of 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 a pigment derivative) and battery performance are not impaired. From the industrial applicability assumed by the invention, it is preferable to use NMP alone.

<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 general formula (1) or an organic dye derivative having an acidic functional group represented by the following general formula (4) is particularly preferable.

First, the triazine derivative having an acidic functional group represented by the general formula (1) will be described.

General formula (1)

^[X 1 _{is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or ^-X 3 ^{-Y-X 4} - represents, X ² and ^{X 4,} each independently, represent -NH- or ^-O-, X 3 _{_{is, -CONH -, - SO 2 NH}} -, - CH 2 NH -, - NHCO- or -NHSO ₂ - and represent , Y represents an alkylene group that may have a substituent, an alkenylene group that may have a substituent, or an arylene group that may have a substituent, and Z represents —SO ₃ M, —COOM, Represents —P (O) (— OM) ₂ or —O—P (O) (— OM) ₂ , M represents one equivalent of a monovalent to trivalent cation, and Q represents —O—R ² , ^{-NH-R 2,} a halogen group, ^-X 1 -R ¹ or ^-X ² -Y-Z, ^R 2 is a hydrogen atom, Have an alkyl group or a substituted group may have a substituent represents an alkenyl group. n represents an integer of 1 to 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 general formula (2) Represents. ]

General 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 Represents —CH ₂ NHCOCH ₂ NH—, and R ³ and R ⁴ each independently represents an organic dye residue, an optionally substituted heterocyclic residue, or an optionally substituted aromatic group. Represents a group ring residue or —YZ, and Y and Z have the same meanings as Y and Z in formula (1). ]

Examples of organic dye residues in R ¹ , R ³ and R ⁴ include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, phthalocyanine dyes, anthraquinones, diaminodianthraquinones, anthrapyrimidines, and flavans Anthraquinone dyes such as Throne, Antanthrone, Indanthrone, Pyrantron, Biolantron, Quinacridone dyes, Dioxazine dyes, Perinone dyes, Perylene dyes, Thioindigo dyes, Isoindolin dyes, Isoindolinone dyes, Residues such as quinophthalone dyes, selenium dyes, metal complex dyes and the like can be mentioned. In particular, in order to increase the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye residue that is not a metal complex dye, among which an azo dye, a diketopyrrolopyrrole dye, a metal-free phthalocyanine dye, Quinacridone dyes and dioxazine dye residues are preferred because they exhibit excellent dispersibility.

Examples of the heterocyclic residue and aromatic ring residue in R ¹ , R ³ , and R ⁴ include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, and benzine. Examples include heterocyclic residues such as thiazole, benztriazole, indole, quinoline, carbazole and acridine, and aromatic ring residues such as benzene, naphthalene, anthracene, fluorene, phenanthrene and anthraquinone. In particular, a heterocyclic residue containing any one of S, N, and O heteroatoms is preferable because it exhibits an effect of excellent dispersibility.

Y in general formula (1) and general formula (2) represents an alkylene group, alkenylene group or arylene group which may have a substituent, but preferably has 20 or less carbon atoms, more preferably 10 or less carbon atoms. . Particularly preferred embodiments include an optionally substituted phenylene group, biphenylene group, naphthylene group or an alkylene group which may have a side chain having 10 or less carbon atoms.

A preferred embodiment of the alkenyl group which may have an alkyl group and a substituted group which may have a substituent in R ² are those having 20 or less carbon atoms. More preferably, an alkyl group which may have a side chain having 10 or less carbon atoms is exemplified. Here, the alkyl group having a substituent and the alkenyl group having a substituent are a group in which a hydrogen atom of an alkyl group or an alkenyl group is substituted with a halogen group such as a fluorine atom, a chlorine atom or a bromine atom, a hydroxyl group or a mercapto group. Can be mentioned.

M represents one equivalent of a monovalent to trivalent cation, for example, a hydrogen ion (proton), a metal cation, or a quaternary ammonium cation. Moreover, when it has two or more M in the structure (one molecule) of a dispersing agent, M may be only one kind of a proton, a metal cation, and a quaternary ammonium cation, and may be a combination of two or more kinds. Examples of the metal cation include metal cations such as lithium, sodium, potassium, calcium, barium, magnesium, aluminum, nickel, and cobalt. The quaternary ammonium cation is a single compound having a structure represented by the general formula (3) or a mixture.

General formula (3)

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

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

Specific examples of the quaternary ammonium cation include dimethylammonium, trimethylammonium, diethylammonium, triethylammonium, hydroxyethylammonium, dihydroxyethylammonium, 2-ethylhexylammonium, dimethylaminopropylammonium, laurylammonium, stearylammonium and the like. However, it is not limited to these.

Next, the organic dye derivative having an acidic functional group represented by the general formula (4) will be described.

General formula (4)

^{[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 ^{-Y-X 10} - ^represents, X 9 _{_{is, -CONH -, - SO 2 NH}} -, - CH 2 NH -, - NHCO- or -NHSO ₂ - ^{represents, X 10} is, -NH- or -O Y represents an alkylene group that may have a substituent, an alkenylene group that may have a substituent, or an arylene group that may have a substituent, and Z represents —SO ₃ M, -COOM, -P (O) (-OM) ₂ or -O-P (O) (-OM) ₂ , M represents one equivalent of a monovalent to trivalent cation, and R ⁹ represents an organic dye residue Represents a group, and n represents an integer of 1 to 4. ]

The organic dye residue of R ^{9 has} the same meaning as the organic dye residue in 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 an organic dye residue that is not a metal complex dye, among which an azo dye, a diketopyrrolopyrrole dye, a metal-free phthalocyanine dye, Quinacridone dyes and dioxazine dye residues are preferred because they exhibit excellent dispersibility.

M in the general formula (4) has the same meaning as M in the general formula (1).

The method for synthesizing the acidic pigment derivative to be used is not particularly limited. For example, Japanese Patent Publication No. 39-28884, Japanese Patent Publication No. 45-11026, Japanese Patent Publication No. 45-29755, Japanese Patent Publication No. 64- They can be synthesized by the methods described in JP 5070, JP 2004-217842 A, and the like.

<Basic pigment derivative>
Among the basic pigment derivatives, a triazine derivative having a basic functional group represented by the following general formula (101) or an organic dye derivative having a basic functional group represented by the following general formula (106) is particularly preferable.

First, the triazine derivative having a basic functional group represented by the general formula (101) will be described.

Formula (101)

X ¹⁰¹ _{is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or ^{^-X} 102 ^-Y 1 ^-X ¹⁰³ - represents, X _{^102, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - NHCO- or -NHSO ₂ - ^{represents, X 103} is, -NH- or -O- and Y ¹ represents an alkylene group that may have a substituent, an alkenylene group that may have a substituent, or an arylene group that may have a substituent, each having 1 to 20 carbon atoms. .
P represents a group represented by any one of the general formula (102), the general formula (103), and the general formula (104).
Q ¹⁰¹ represents —O—R ¹⁰² , —NH—R ¹⁰² , a halogen group, —X ¹⁰¹ —R ^101, or a group represented by any one of the general formula (102), the general formula (103), and the general formula (104). Represents.
R ¹⁰² represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or an aryl group that may have a substituent.
o represents an integer of 1 to 4.

General formula (102)

General formula (103)

General formula (104)

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 - represents a. X ¹⁰⁵ represents -NH- or ^{-O-, X 106} represents a direct _{_{bond, -SO 2 -, - CO -}} , - CH 2 NHCOCH 2 -, - CH 2 NHCONHCH 2 - or -CH ₂ - represents a .
v ¹ represents an integer of 1 to 10.
R ¹⁰³ and R ¹⁰⁴ represent respectively independently, a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group or a heterocyclic residue, R ¹⁰³ And R ¹⁰⁴ may combine to form a ring.
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, a heterocyclic residue which may have a substituent, an aromatic ring residue which may have a substituent, or a group represented by the following general formula (105). .

General formula (105)

T represents -X ¹⁰⁸ -R ¹¹⁰ or W ¹ , and U represents -X ¹⁰⁹ -R ¹¹¹ or W ² .
W ¹ and W ² are each independently —O—R ¹⁰² , —NH—R ¹⁰² , a halogen group or a group represented by any one of the general formula (102), the general formula (103), and the general formula (104). Represents.
X ¹⁰⁷ represents -NH- or ^{-O-, X 108} and ^{X 109} each independently, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH- or - CH ₂ NHCOCH ₂ NH— is represented.
R ¹¹⁰ and R ¹¹¹ each independently represents an organic dye residue, a heterocyclic residue which may have a substituent, or an aromatic ring residue which may have a substituent.

Examples of the organic dye residue in R ¹⁰¹ of the general formula (101) and R ¹¹⁰ and R ¹¹¹ of the general formula (105) include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, and phthalocyanine dyes. Dyes, diaminodianthraquinones, anthrapyrimidines, flavantrons, anthanthrones, indantrons, pyranthrones, violanthrones, anthraquinone dyes, quinacridone dyes, dioxazine dyes, perinone dyes, perylene dyes, thioindigo dyes, iso Examples include residues such as indoline dyes, isoindolinone dyes, quinophthalone dyes, selenium dyes, metal complex dyes, and the like. In particular, in order to enhance the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye residue that is not a metal complex dye.

Examples of the heterocyclic residue and the aromatic ring residue in R ¹⁰¹ of the general formula (101) and R ¹¹⁰ and R ¹¹¹ of the general formula (105) include thiophene, furan, pyridine, pyrazine, triazine, pyrazine, pyrrole, Examples include imidazole, isoindoline, isoindolinone, benzimidazolone, benzthiazole, benztriazole, indole, quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, acridone and the like. These heterocyclic residues and aromatic ring residues are alkyl groups (methyl group, ethyl group, butyl group, etc.), amino groups, alkylamino groups (dimethylamino group, diethylamino group, dibutylamino group, etc.), nitro groups. Hydroxyl group, alkoxyl group (methoxy group, ethoxy group, butoxy group, etc.), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) And a substituent such as a phenylamino group (which may be substituted with an alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) May be.

R ¹⁰³ and R ¹⁰⁴ represent respectively independently, a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group or a heterocyclic residue, R ¹⁰³ And R ¹⁰⁴ may combine to form a ring. In particular, a hydrogen atom is preferable because it is considered that the effect of suppressing metal deposition in the battery is high. Y ¹ in the general formula (101) and the general formula (105) represents an alkylene group, an alkenylene group or an arylene group which may have a substituent having 20 or less carbon atoms, and preferably has a substituent. Examples thereof include 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.

Next, an organic dye derivative having a basic functional group represented by the general formula (106) will be described.

Formula (106)

Z101 is a group represented by the following general formula (107), general formula (108), or general formula (109). m represents an integer of 1 to 4.

General formula (107)

Formula (108)

General formula (109)

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 - represents a. 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 - represents a . Y ² 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, having 1 to 20 carbon atoms.
v ² represents an integer of 1 to 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, R ²³ And R ²⁴ may combine to form a ring. In particular, a hydrogen atom is preferable because it is considered that the effect of suppressing metal deposition in the battery is high.
R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ each independently represents 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, or an aromatic ring residue which may have a substituent.
Examples of the organic dye residue in R ²² include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, phthalocyanine dyes, diaminodianthraquinone, anthrapyrimidine, flavantrons, anthanthrone, indanthrone, Anthraquinone dyes such as pyranthrone, violanthrone, quinacridone dyes, dioxazine dyes, perinone dyes, perylene dyes, thioindigo dyes, isoindoline dyes, isoindolinone dyes, quinophthalone dyes, selenium dyes, Examples include residues of metal complex dyes. In particular, in order to enhance the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye residue that is not a metal complex dye.

Examples of the heterocyclic residue and aromatic ring residue in R ²² include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, benzthiazole, benztriazole, and indole. , Quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, acridone and the like. These heterocyclic residues and aromatic ring residues are alkyl groups (methyl group, ethyl group, butyl group, etc.), amino groups, alkylamino groups (dimethylamino group, diethylamino group, dibutylamino group, etc.), nitro groups. Hydroxyl group, alkoxyl group (methoxy group, ethoxy group, butoxy group, etc.), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) And a substituent such as a phenylamino group (which may be substituted with an alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) May be.

Examples of the amine component used for forming the substituents represented by the general formulas (102) to (104) and the general formulas (107) to (109) include 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, dicyclohexylamine, di (2-ethyl) Hexyl) amine Dioctylamine, N, N-methyloctadecylamine, didecylamine, diallylamine, N, N-ethyl-1,2-dimethylpropylamine, N, N-methylhexylamine, dioleylamine, distearylamine, N, N-dimethylamino Methylamine, 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-dibutylamino Tylamine, N, N-diisobutylaminopentylamine, N, N-methyl-laurylaminopropylamine, N, N-ethyl-hexylaminoethylamine, N, N-distearylaminoethylamine, N, N-dioleylaminoethylamine, N, N-distearylaminobutylamine, piperidine, 2-pipecoline, 3-pipecoline, 4-pipecoline, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, 3-piperidinemethanol, pipecolic acid, isonipecotine Acid, methyl isonicopetinate, ethyl isonicopetinate, 2-piperidineethanol, pyrrolidine, 3-hydroxypyrrolidine, N-aminoethylpiperidine, N-aminoethyl-4-pipecholine, N-aminoethylmorpholine, N-aminopropylpiperi Gin, N-aminopropyl-2-pipecoline, N-aminopropyl-4-pipecoline, N-aminopropylmorpholine, N-methylpiperazine, N-butylpiperazine, N-methylhomopiperazine, 1-cyclopentylpiperazine, 1-amino -4-methylpiperazine, 1-cyclopentylpiperazine and the like.

The method for synthesizing the organic dye derivative having a basic functional group or the triazine derivative having a basic functional group to be used is not particularly limited, but JP-A-54-62227 and JP-A-56- 118462, JP 56-166266, JP 60-88185, JP 63-305173, JP 3-2676, JP 11-199796, and the like. It can be synthesized by the method.

For example, an organic dye derivative having a basic functional group includes a substituent represented by the formula (110) to the formula (113) in an organic dye, a heterocyclic compound (eg, acridone) or an aromatic ring compound (eg, anthraquinone). After the introduction, these substituents and amine components (for example, N, N-dimethylaminopropylamine, N-methylpiperazine, diethylamine or 4- [4-hydroxy-6- [3- (dibutylamino) propylamino] -1 , 3,5-triazin-2-ylamino] aniline and the like) can be synthesized.
Formula (110) -SO ₂ Cl
Formula (111) -COCl
Formula (112) -CH ₂ NHCOCH ₂ Cl
Formula (113) -CH ₂ Cl
In addition, for example, when a substituent represented by the formula (110) is introduced, an organic dye, a heterocyclic compound (for example, acridone) or an aromatic ring compound (for example, anthraquinone) is dissolved in chlorosulfonic acid, A chlorinating agent such as thionyl chloride is reacted, but depending on conditions such as reaction temperature and reaction time, a formula to be introduced into an organic dye, a heterocyclic compound (eg, acridone) or an aromatic ring compound (eg, anthraquinone) The number of substituents represented by (110) can be controlled.

When introducing the substituent represented by the formula (111), first, an organic dye having a carboxyl group, a heterocyclic compound (for example, acridone) or an aromatic ring compound (for example, 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 is exemplified.

During the reaction of the substituents represented by the formulas (110) to (113) with the amine component, some of the substituents represented by the formulas (110) to (113) are hydrolyzed to replace chlorine with hydroxyl groups. There are things to do. In that case, the substituent represented by the formula (110) is a sulfonic acid group, and the substituent represented by the formula (111) is a carboxylic acid group. A metal or a salt of the above amine may be formed.

When the organic dye is an azo dye, a substituent represented by the formula (107) to the formula (109) or the following general formula (114) is previously introduced into the diazo component or the coupling component, and then the coupling is performed. An azo organic dye derivative can also be produced by carrying out the reaction.

Formula (114)

X ¹⁰¹ _{is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or ^{^-X} 102 ^-Y 1 ^-X ¹⁰³ - represents, X _{^102, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - NHCO- or -NHSO ₂ - ^{represents, X 103} each independently -NH- or -O Y ¹ 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, which has 1 to 20 carbon atoms, Represents.
P represents a substituent represented by any one of the general formulas (102), (103) and the general formula (104).
Q ¹⁰¹ represents —O—R ¹⁰² , —NH—R ¹⁰² , a halogen group, —X ¹⁰¹ —R ^101, or a substitution represented by any of the general formula (102), (103), or the general formula (104) Represents a group.
R ¹⁰² represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or an aryl group that may have a substituent.

The triazine derivative having a basic functional group is, for example, a substituent represented by formula (107) to formula (109) or general formula (114) in at least one chlorine of cyanuric chloride using cyanuric chloride as a starting material. It is obtained by reacting an amine component (for example, N, N-dimethylaminopropylamine or N-methylpiperazine etc.) to form, 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, and is a triazine derivative having an acidic or basic functional group. More preferably, it is more preferably a triazine derivative having an acidic functional group, and particularly preferably a triazine derivative having no azo bond and having an acidic functional group.

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

<Method for producing carbon black dispersion>
The dispersion liquid of the present invention mainly comprises carbon black using polyvinyl alcohol as a dispersant (first invention and third invention) or using polyvinyl alcohol and a pigment derivative as a dispersant (second invention). Dispersed in NMP. In this case, the dispersant and carbon black are added simultaneously or sequentially and mixed to disperse the dispersant while acting (adsorbing) on the carbon black. However, in order to more easily produce a carbon black dispersion, the dispersant is dissolved, swollen, or dispersed in NMP, and then the carbon black is added to the liquid and mixed to disperse the dispersant in carbon. It is more preferable to act (adsorb) on black. In addition, as a powder other than carbon black, for example, when an electrode active material for a secondary battery is added and used as an electrode mixture liquid, a dispersing agent, carbon black and an electrode active material are simultaneously charged and dispersed in NMP. Processing may be performed.

As the dispersing device, a dispersing device usually used for pigment dispersion or the like can be used. For example, mixers such as dispersers, homomixers, planetary mixers, homogenizers (such as “Clearmix” manufactured by M Technique, “Fillmix” manufactured by PRIMIX, “Abramix” manufactured by Silverson, etc.), paint conditioners ( Red Devil Co.), colloid mill ("PUC Colloid Mill" manufactured by PUC, "Colloid Mill MK" manufactured by IKA), cone mill ("Cone Mill MKO" manufactured by IKA, etc.), ball mill, sand mill (Shinmaru Enterprises) “Dynomill”, etc.), Attritor, Pearl Mill (“DCP Mill” manufactured by Eirich), Coball Mill and other media type dispersers, Wet Jet Mill (“Genus PY” manufactured by Genus, “Starburst” manufactured by Sugino Machine) "Nanomizer" manufactured by Nanomizer ), M Technique Co., Ltd. "Claire SS-5", Nara Machinery Co., Ltd. "MICROS" media-less dispersing machine such as, but other roll mill, and the like, but is not limited to these.

Next, the case where a dispersion is produced after the surface treatment of carbon black with a dispersant by dry treatment will be described. A carbon black dispersion can be obtained by adding and mixing a mixture of carbon black and dispersant obtained by the following dry treatment in NMP. Examples of a method for obtaining carbon black surface-treated with a dispersant include a dry treatment method.

Dry processing is to make the dispersant act (adsorb) on the surface of the carbon black while mixing, pulverizing, and the like of the carbon black and the dispersant with a dry processing apparatus at room temperature or under heating. However, it is not necessary for the dispersant to be completely adsorbed on the carbon black surface, and there may be no practical problem as long as it can be mixed homogeneously to some extent. The equipment to be used is not particularly limited. Media type dispersers such as paint conditioner (manufactured by Red Devil), ball mill, attritor, vibration mill, kneader, roller mill, stone mill, planetary mixer, fen Dispersing and kneading machines such as Shell Mixer, Hybridizer (Nara Machinery Co., Ltd.), Mechano Micros (Nara Machinery Co., Ltd.), Mechano Fusion System AMS (Hosokawa Micron Co., Ltd.) can be used. Therefore, it is more preferable to use a medialess dispersion / kneading machine.

Further, at this time, an organic solvent may be added as long as the treated product does not become a gel. It is expected that the interaction between the carbon black and the dispersing agent is promoted by improving the wetting or (partly) dissolution of the dispersing agent by the addition of the solvent and the wetting of the carbon black with respect to the dispersing agent. The solvent used at this time is not particularly limited. However, when a solvent other than NMP is used, it is desirable to dry after the treatment. The amount of organic solvent added varies depending on the material used, but is 0.5 to 100% by weight based on the amount of dispersant added. Further, the inside of the dry processing apparatus may be treated as a deoxygenated atmosphere by flowing nitrogen gas or the like as necessary.

The dry treatment time can be arbitrarily set depending on the apparatus used and the desired degree of kneading. By performing these dry treatments, a powdery or lump treated product can be obtained. The obtained processed product may be further dried and pulverized.

In the case of the first invention (dispersant is mainly polyvinyl alcohol alone), the amount of dispersant added to carbon black is preferably 0.65 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of carbon black. 0.65 parts by weight or more and 10 parts by weight or less are more preferable, 1 part by weight or more and 10 parts by weight or less are more preferable, 1 part by weight or more and 8 parts by weight or less are more preferable, 2 parts by weight or more and 8 parts by weight or less. The following are particularly preferred: In the case of the second invention (the dispersant is a combination of polyvinyl alcohol and a pigment derivative), the amount is preferably 50 parts by weight or less, more than 0.5 parts by weight and 40 parts by weight with respect to 100 parts by weight of carbon black. Parts by weight or less, preferably 0.5 parts by weight or more and 20 parts by weight or less, more preferably 1 part by weight or more and 15 parts by weight or less, still more preferably 1 part by weight or more and 10 parts by weight or less. As mentioned above, 8 weight part or less is especially preferable. In the case of the third invention (dispersant is mainly polyvinyl alcohol alone), the amount is more than 8 parts by weight, preferably 40 parts by weight or less, more than 8 parts by weight, 30 parts by weight with respect to 100 parts by weight of carbon black. Is more preferably 8 parts by weight or more, more preferably 25 parts by weight or less, more preferably 8 parts by weight, further preferably 20 parts by weight or less, particularly preferably 8 parts by weight or more 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 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of carbon black. Preferably, 0.15 parts by weight or more and 10 parts by weight or less are more preferable, 0.2 parts by weight or more and 8 parts by weight or less are more preferable, 0.2 parts by weight or more and 4 parts by weight or less are more preferable, 0.4 Part by weight or more and 4 parts by weight or less are particularly preferable.

When the dispersant is a combination of polyvinyl alcohol and a pigment derivative, the proportion 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 with respect to 100 parts by weight of the dispersant. More preferred is 25 parts by weight or less, and particularly preferred is 25 parts by weight or more and 75 parts by weight or less.

The amount of the dispersant added to 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, the amount of the dispersant adsorbed on the carbon black, and the like.

In particular, the amount of polyvinyl alcohol added relative to the specific surface area of carbon black is important. When the saponification degree of polyvinyl alcohol is 50 to 95 mol% (preferably 60 to 85 mol%), the BET specific surface area of carbon black is Xm ² / g. When the addition amount of polyvinyl alcohol to 1 g of carbon black is aXg, a carbon black dispersion having a high concentration, low viscosity and good long-term storage stability when a is in the range of 0.00017 ≦ a ≦ 0.00256 It has been found that there is a critical range in which can be produced.

From the viewpoint of obtaining better dispersion and battery characteristics, the range of 0.00019 ≦ a ≦ 0.00217 is more preferable, the range of 0.00026 ≦ a ≦ 0.00145 is more preferable, and 0 Particularly preferred is a range of .00051 ≦ a ≦ 0.00145.

By blending at the above ratio, the viscosity of the carbon black dispersion can be lowered, and it becomes easy to obtain a dispersion 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.

The positive electrode active material for the lithium ion secondary battery is not particularly limited, but metal oxides capable of doping or intercalating lithium ions, metal compounds such as metal sulfides, and conductive polymers are used. be able to. Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, transition metal sulfide powders such as TiS ₂ and FeS, and the like. In addition, conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene can also be used. Moreover, you may mix and use said inorganic compound and organic compound.

The negative electrode active material for the lithium ion secondary battery is not particularly limited as long as it can be doped or intercalated with lithium ions. For example, metal Li, alloys thereof such as tin alloys, silicon alloys, lead alloys, etc., Li _X Fe ₂ O ₃ , Li _X Fe ₃ O ₄ , Li _X WO ₂ , lithium titanate, lithium vanadate, silicon Metal oxides such as lithium oxide, conductive polymer such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon and hard carbon, artificial graphite such as highly graphitized carbon materials, or natural Examples thereof include carbonaceous powders such as graphite, carbon black, mesophase carbon black, resin-fired carbon materials, air-growth carbon fibers, and carbon fibers. These negative electrode active materials can be used alone or in combination.

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

In 3rd invention, the addition amount of the polyvinyl alcohol as a dispersing agent is 0.05 weight part or more with respect to 100 weight part of the amount of all the solid components contained in the carbon black dispersion liquid containing an electrode active material, Less than 2 parts by weight is preferable, 0.05 part by weight or more and less than 1.5 parts by weight are more preferable, 0.05 part by weight or more and less than 1.25 parts by weight are further preferable, 0.05 part by weight or more and 1 part by weight Less than 1 part by weight is more preferable, and 0.1 part by weight or more and less than 1 part by weight is particularly preferable.

<Other additives>
Conventionally known dispersants, resins, additives, and the like may be used in combination for the purpose of adjusting the physical properties of the coating film and the like as long as the object of the present invention is not affected. Examples of such a dispersant include a polyvinyl acetal resin (such as polyvinyl butyral resin), a polyvinyl pyrrolidone resin, a conventionally known dye derivative, and a low molecular weight surfactant. Examples of the resin include polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene, polypropylene, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid, polyacrylamide, and polyurethane. , Polydimethylsiloxane, epoxy resin, acrylic resin, polyester resin, melamine resin, phenol resin, styrene butadiene rubber and other rubbers, lignin, pectin, gelatin, xanthan gum, welan gum, succinoglycan, cellulosic resin, polyalkylene oxide, Examples include polyvinyl ether, chitins, chitosans, starch and the like. Examples of the additive include phosphorus compounds, sulfur compounds, organic acids, amine compounds and 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.

<Uses of carbon black dispersion>
The field of application of the carbon black dispersion is not particularly limited, but is a field that requires light-shielding properties, electrical conductivity, durability, jetness, etc., such as gravure ink, offset ink, back coat for magnetic recording media, static It is possible to provide a stable and uniform composition in electric toner, ink jet, automobile paint, fiber / plastic forming material, battery electrode, and electrophotographic seamless belt. Among them, the use of NMP, compatibility with polyvinylidene fluoride, polyimide precursors, and the like, and the strength and flexibility of the formed coating film and molded product, the electrode for lithium ion secondary battery, It is suitably used for electric double layer capacitor electrodes, lithium ion capacitor electrodes, electrophotographic seamless belts, and the like.

Using a carbon black dispersion, and further adding a binder such as polyvinylidene fluoride and polytetrafluoroethylene, an electrode for a lithium ion secondary battery, an electrode for an electric double layer capacitor, a primer layer for an electrode for a lithium ion capacitor, Lithium ion rechargeable battery electrodes and electricity by adding positive and negative active materials such as lithium transition metal composite oxides such as lithium cobaltate and lithium manganate, graphite, activated carbon, graphite, carbon nanotubes and carbon nanofibers The electrode layer of the electrode for double layer capacitors and the electrode for lithium ion capacitors can be manufactured. The electrophotographic seamless belt can be produced by a conventionally known method using a carbon black dispersion, a polyimide, a polyamideimide, or the like as a conductive material and a precursor thereof as components.

<Electrode>
By coating and drying a carbon black dispersion containing a positive electrode active material or a negative electrode active material on a current collector, a battery electrode mixture layer can be formed and an electrode can be obtained.

(Current collector)
The material and shape of the current collector used for the electrode are not particularly limited, and those suitable for various secondary batteries can be appropriately selected. For example, examples of the material for the current collector include metals and alloys such as aluminum, copper, nickel, titanium, and stainless steel. In general, a flat foil is used as the shape, but a roughened surface, a perforated foil, or a mesh current collector can also be used.

(Battery electrode mixture layer)
There is no restriction | limiting in particular as a method of apply | coating a mixture slurry and the composition for base layer formation on a collector, A well-known method can be used. Specific examples include die coating method, dip coating method, roll coating method, doctor coating method, knife coating method, spray coating method, gravure coating method, screen printing method or electrostatic coating method, and the like. Examples of methods that can be used include standing drying, blower dryers, hot air dryers, infrared heaters, and far-infrared heaters, but are not particularly limited thereto.

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

<Secondary battery>
A secondary battery can be obtained by using an electrode for at least one of the positive electrode and the negative electrode. Secondary batteries include lithium ion secondary batteries, sodium ion secondary batteries, magnesium secondary batteries, alkaline secondary batteries, lead storage batteries, sodium sulfur secondary batteries, lithium air secondary batteries, etc. In the secondary battery, conventionally known electrolytes, separators, and the like can be used as appropriate.

(Electrolyte)
A case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, an electrolyte containing lithium dissolved in a non-aqueous solvent is used. As the 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 , LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, or LiBPh _4, but are not limited thereto.

The non-aqueous solvent is not particularly limited. For example, carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate; γ-butyrolactone, γ-valerolactone, and γ Lactones such as octanoic lactone; tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1, Glymes such as 2-dibutoxyethane; esters such as methyl formate, methyl acetate, and methyl propionate; sulfoxides such as dimethyl sulfoxide and sulfolane; and nitriles such as acetonitrile. And the like. These solvents may be used alone or in combination of two or more.

(separator)
Examples of the separator include, but are not limited to, a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, a polyamide nonwoven fabric and those obtained by subjecting them to a hydrophilic treatment.

(Battery structure / configuration)
Although the structure of the lithium ion secondary battery is not particularly limited, it is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary. For the purpose of use, such as a paper type, a cylindrical type, a button type, and a laminated type. Various shapes can be obtained.

<Example relating to the first invention>
Hereinafter, the first invention will be mainly described in detail based on examples. However, the following examples are not necessarily related only to the first invention, but fall within the scope of the second invention and the third invention. If any, it can be referred to as an embodiment of these inventions. Moreover, this invention is not limited to a following example, unless the summary is exceeded. In this example, “part” represents “part by weight” and “%” represents “% by weight”.

The carbon black (sometimes abbreviated as “CB”), polyvinyl alcohol (sometimes abbreviated as “PVA”), binder, electrode active material, and the like used in Examples and Comparative Examples are shown below. 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 Corporation): furnace black, average primary particle size 30 nm, specific surface area 74 m ² / g. Hereinafter, it is abbreviated as # 30.
# 5 (Mitsubishi Chemical Co., Ltd.): Furnace black, average primary particle size 76 nm, specific surface area 29 m ² / g. Hereinafter, it is abbreviated as # 5.
MA77 (manufactured by Mitsubishi Chemical Corporation): oxidized carbon black, average primary particle size of 23 nm, specific surface area of 130 m ² / g. Hereinafter, it is abbreviated as MA77.
Denka black HS-100 (manufactured by Denki Kagaku Kogyo): acetylene black, average primary particle size 48 nm, specific surface area 39 m ² / g. Hereinafter, it is abbreviated as HS-100.
Denka black granular product (manufactured by Denki Kagaku Kogyo): acetylene black, average primary particle size 35 nm, specific surface area 69 m ² / g. Hereinafter, it is abbreviated as a granular product.
EC-300J (manufactured by Akzo): Ketjen black, average primary particle size 40 nm, specific surface area 800 m ² / g. Hereinafter, it is abbreviated as 300J.

(Measurement method of average primary particle size of carbon black)
The average primary particle size (MV) of carbon black was measured (calculated) by the method shown below. A sample for measurement was prepared by adding propylene glycol monomethyl ether acetate to a carbon black powder, adding a small amount of Disperbyk-161 as a resin-type dispersant, and dispersing in a water bath of an ultrasonic cleaner for 1 minute. This sample was applied to a measurement target, dried, and photographed with a transmission electron microscope (Transmission Electron Microscope H-7650, manufactured by Hitachi High-Technologies Corporation) to observe 100 or more primary particles of carbon black. In the photographed image, an arbitrary 100 carbon black particles are selected, the average value of the minor axis diameter and major axis diameter of the primary particles is defined as the particle diameter (d), and then the individual carbon blacks are obtained. Considering it as a sphere having a diameter (d), the volume (V) of each particle was determined, and this operation was performed on 100 carbon black particles, and the calculation was performed using the following equation (1).
Formula (1) MV = Σ (V · d) / Σ (V)

<Polyvinyl alcohol>
Kuraray Poval L-8 (manufactured by Kuraray): polyvinyl alcohol, saponification degree 71 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 5.5 mPa · s. Hereinafter, it is abbreviated as L-8.
Kuraray Poval L-10 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 72 mol%, average polymerization degree 1000 or less. Hereinafter, abbreviated as L-10.
Kuraray Poval C-506 (manufactured by Kuraray Co., Ltd.): cation-modified polyvinyl alcohol, saponification degree 76 mol%, average polymerization degree 600, 4% aqueous solution viscosity 5.1 mPa · s. Hereinafter, this is abbreviated as C-506.
Kuraray Poval KL-506 (manufactured by Kuraray Co., Ltd.): anion-modified polyvinyl alcohol, saponification degree 77 mol%, average polymerization degree 600, 4% aqueous solution viscosity 5.6 mPa · s. Hereinafter, it is abbreviated as KL-506.
-Gohsenol KL-05 (manufactured by Nippon Synthetic Chemical Industry): polyvinyl alcohol, saponification degree 82 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 4.4 mPa · s. Hereinafter, it is abbreviated as KL-05.
Kuraray Poval PVA-205 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 88 mol%, average polymerization degree 500, 4% aqueous solution viscosity 5.0 mPa · s. Hereinafter, it is abbreviated as PVA-205.
Goosephimer LL-02 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.): polyvinyl alcohol, saponification degree 50 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 7.7 mPa · s. Hereinafter, abbreviated as LL-02.
Synthetic product 1: polyvinyl alcohol, saponification degree 60 mol%, average polymerization degree about 500, 4% aqueous solution viscosity 5.2 mPa · s.
Synthetic product 2: polyvinyl alcohol, saponification degree 85 mol%, average polymerization degree about 500, 4% aqueous solution viscosity 5.7 mPa · s.
Synthetic product 3: polyvinyl alcohol, saponification degree 72 mol%, average polymerization degree about 100, 4% aqueous solution viscosity 2.0 mPa · s.
Synthetic product 4: polyvinyl alcohol, saponification degree 70 mol%, average polymerization degree about 1500, 4% aqueous solution viscosity 19.8 mPa · s.
The synthetic product 1, the synthetic product 2, the synthetic product 3, and the synthetic product 4 were obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the industry.

<Binder>
KF polymer W1100 (manufactured by Kureha): polyvinylidene fluoride (PVDF), hereinafter abbreviated as PVDF.
-KF polymer W7300 (manufactured by Kureha): polyvinylidene fluoride (PVDF), hereinafter abbreviated as # 7300.

<Active material>
HLC-22 (Honjo Chemical Co., Ltd.): positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle size 6.6 μm, specific surface area 0.62 m ² / g. Hereinafter, abbreviated as LCO.
MCMB6-28 (manufactured by Osaka Gas Chemical Co.): negative electrode active material mesophase carbon (MFC), average particle size 5-7 μm, specific surface area 4 m ² / g. Hereinafter, abbreviated as MFC.

<Evaluation of carbon black dispersion>
The carbon black dispersions obtained in Examples and Comparative Examples were evaluated by measuring the viscosity (its storage stability) and the average particle diameter after dispersion (its storage stability).

The viscosity value was measured using a B-type viscometer (“BL” manufactured by Toki Sangyo Co., Ltd.), and the dispersion was sufficiently stirred with a spatula at a dispersion temperature of 25 ° C. and a B-type viscometer rotor rotation speed of 60 rpm. Then went immediately. The rotor used for the measurement is No. when the viscosity value is less than 100 mPa · s. No. 1 is 100 or more and less than 500 mPa · s. 2 is 500 or more and less than 2000 mPa · s. 3 is 2000 or more and less than 10,000 mPa · s. Four of each were used. The case where the obtained viscosity value was 10,000 mPa · s or more was described as “> 10000”, but this indicates that the viscosity was so high that it could not be evaluated with the B-type viscometer used for the evaluation. The lower the viscosity, the better the dispersibility, and the higher the viscosity, the poor the dispersibility. The storage stability was evaluated from the change in viscosity value after the carbon black dispersion was stored at 50 ° C. for 30 days. The smaller the change, the better the stability.

In addition, the average particle size after dispersion is measured by diluting the carbon black dispersion to an appropriate concentration with NMP, and then using the ultrasonically treated liquid as a measurement sample. The measurement was carried out by measuring the average particle diameter (D50 value) using “Nanotrack UPA-EX” manufactured by Nikkiso Co., Ltd., light source wavelength 780 nm). Various measurement conditions were such that the loading index value of the dispersion diluted with NMP by the above method was 0.7 or more and 1.3 or less, the particle conditions were absorbent particles, particle shape non-spherical, density 1.80, and the solvent conditions were The solvent refractive index was 1.47, the solvent viscosity was 1.80 mPa · s at a liquid temperature of 20 ° C., the solvent viscosity was 1.65 mPa · s at a liquid temperature of 25 ° C., and the obtained median diameter was expressed as a D50 value. The measurement result is obtained by measuring the background value of the NMP solvent at a liquid temperature of 25 ° C., filling a sample with the liquid temperature of 25 ° C. prepared by the above method into a measurement container, and performing the measurement under the measurement conditions. It was. When the same dispersion treatment is performed using the same carbon black, the smaller the D50 value, the better the dispersibility, and the greater the value, the poorer the dispersibility. The storage stability was evaluated from the change in D50 value after storing the carbon black dispersion at 50 ° C. for 30 days. The smaller the change, the better the stability.

<Preparation of carbon black dispersion>
(Carbon black dispersion using polyvinyl alcohol with different saponification degrees)
[Example 1-1 to Example 1-7]
In accordance with the composition shown in Table 1-1, NMP and various polyvinyl alcohols were charged into a glass bottle, mixed and dissolved or mixed and dispersed, then various carbon blacks were added, and 1.25 mmφ zirconia beads were used as media for 2 hours with a paint shaker. Each carbon black dispersion was obtained by dispersing. In all cases, the viscosity was low, the D50 value was small, and the storage stability was good. Moreover, it became clear that the presence or absence of the modification | denaturation of polyvinyl alcohol does not have big influence on the performance as a dispersing agent.

[Comparative Example 1-1 to Comparative Example 1-2]
In accordance with the composition shown in Table 1-1, NMP and various polyvinyl alcohols were charged into a glass bottle, mixed and dissolved, or mixed and dispersed. Then, various carbon blacks were added, and 1.25 mmφ zirconia beads were used as media, and 2 on a paint shaker. Time dispersed. However, all of the obtained dispersions are in a state of extremely high viscosity and have a large D50 value, which indicates that carbon black cannot be sufficiently dispersed. From this result, even if the a value calculated from the addition amount of polyvinyl alcohol relative to the specific surface area of carbon black is within the range of 0.00017 ≦ a ≦ 0.00256, the degree of saponification is less than 60 mol% or 85 mol%. It was clarified that a carbon black dispersion liquid having a desired high concentration and low viscosity could not be obtained when exceeding the polyvinyl alcohol was used.

(Different types of carbon black and carbon black dispersions with different polyvinyl alcohol content)
[Example 1-8 to Example 1-24]
In accordance with the composition shown in Table 1-1, NMP and polyvinyl alcohol are charged into a glass bottle, mixed and dissolved or mixed and dispersed, then various carbon blacks are added, and 1.25 mmφ zirconia beads are used as a medium and dispersed for 2 hours in a paint shaker. Each carbon black dispersion was obtained. In all cases, the viscosity was low, the D50 value was small, and the storage stability was good.

[Comparative Example 1-3, Reference Example 1-1]
In accordance with the composition shown in Table 1-1, NMP and polyvinyl alcohol are charged into a glass bottle, mixed and dissolved or mixed and dispersed, then various carbon blacks are added, and 1.25 mmφ zirconia beads are used as a medium and dispersed for 2 hours in a paint shaker. Each carbon black dispersion was obtained. All of the obtained dispersions were in a state of extremely high viscosity and the D50 value was large, so that the carbon black could not be sufficiently dispersed. From this result, even when polyvinyl alcohol having a saponification degree of 60 to 85 mol% is used, the a value calculated from the addition amount of polyvinyl alcohol with respect to the specific surface area of carbon black is in the range of 0.00017 ≦ a ≦ 0.00256. In other cases, it became clear that a desired high concentration and low viscosity carbon black dispersion could not be obtained.

<Preparation of carbon black dispersion containing binder>
[Example 2-1 to Example 2-16]
In accordance with the composition shown in Table 1-2, NMP, various polyvinyl alcohols, and various binders are charged into a glass bottle, and after thoroughly mixing, dissolving, or dispersing, various carbon blacks are added and dispersed with a homogenizer for 1 hour. A liquid was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Example 2-17]
According to the composition shown in Table 1-2, NMP and polyvinyl alcohol were charged into a glass bottle and thoroughly mixed and dissolved. Next, a powder mixture in which carbon black and PVDF were homogeneously mixed was prepared, and this was added to an NMP solution of polyvinyl alcohol prepared in advance. Then, it disperse | distributed for 1 hour with the homogenizer, and obtained the carbon black dispersion liquid. There were no coarse particles, the viscosity was low, and the storage stability was good.

[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 obtain each carbon black dispersion. It was. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Comparative Examples 2-1 to 2-5]
In accordance with the composition shown in Table 1-2, NMP, various polyvinyl alcohols and PVDF are charged into a glass bottle, and after thoroughly mixing, dissolving or mixing, various carbon blacks are added and dispersed with a homogenizer for 1 hour. A liquid was obtained. However, it was revealed that the viscosity of the obtained dispersion was as high as that prepared without adding a binder, and the carbon black and binder concentrations could not be further improved.

From Table 1-2, when a resin that can be dissolved or dispersed in NMP is used as a binder, the properties of the resulting carbon black dispersion are as follows when the dispersion is prepared without adding the binder of Table 1-1. Similarly, it can be seen that a dispersion having high concentration and low viscosity and good storage stability can be obtained.

<Preparation of carbon black dispersion containing positive electrode active material or 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, the positive electrode active material was used for the carbon black dispersions containing the binders obtained in Examples 2-1 to 2-3 and Example 2-5 to Example 2-14. A certain LCO was charged and thoroughly mixed with a disper to obtain each liquid mixture. Since the carbon black dispersion used had a low viscosity, a large amount of LCO could be added, and the resulting mixture was also in a low viscosity state.

[Example 3-4]
After preparing a powder mixture in which 2.67 parts of granular product, 1.33 parts of PVDF, 0.13 part of L-8, and 62.7 parts of LCO are homogeneously mixed, 33.17 parts of NMP are prepared. Half of the total amount of the powder mixture was added and treated 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. A carbon black dispersion containing LCO as an active material was obtained. The obtained liquid was in a low viscosity state as in Example 3-2.

[Example 3-15 to Example 3-18]
In accordance with the composition shown in Table 1-3, MFC, which is a negative electrode active material, was charged into the carbon black dispersion containing the binder obtained in Examples 2-1 to 2-3 and Example 2-9. The mixture was sufficiently mixed with a disper to obtain each mixture. Since the carbon black dispersion used had a low viscosity, a large amount of MFC could be added, and the resulting mixture was also in a low viscosity state.

[Comparative Examples 3-1 to 3-3]
In accordance with the composition shown in Table 1-3, LCO as the positive electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Examples 2-3 to 2-5 and mixed well with a disper. Each liquid mixture was obtained. In any case, since the viscosity value of the carbon black dispersion used is high, the increase in the viscosity value when LCO is added is larger than in Examples 3-1 to 3-14, and the stability is increased. The increase in viscosity in the evaluation test was also large.

[Comparative Examples 3-4 to 3-6]
According to the composition shown in Table 1-3, the carbon black dispersion containing the binder obtained in Comparative Examples 2-3 to 2-5 was charged with MFC as a negative electrode active material, and thoroughly mixed with a disper. Each liquid mixture was obtained. In any case, since the viscosity value of the carbon black dispersion used is high, the increase in the viscosity value when MFC is added is larger than that in Examples 3-15 to 3-18, and the stability is increased. The increase in viscosity in the evaluation test was also large.

<Preparation of battery electrode composite layer>
After applying 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 liquid on a polyethylene terephthalate (PET) film using a doctor blade Then, the film was dried at 120 ° C. under reduced pressure for 30 minutes, and a coating film (battery electrode mixture layer) having a film thickness of 100 μm was produced after drying.
Evaluation of the obtained battery electrode mixture layer was performed by surface resistance and coating film appearance. The surface resistance was measured using Loresta-GP (manufactured by Mitsubishi Chemical Analytech) according to JIS K7194.
The smaller the numerical value, the better the surface resistance. Further, the appearance of the coating film was visually evaluated as ◯: no problem (good), Δ: spotted pattern (bad), and x: coarse-grained stripes (very bad).

[Example 4-1 to Example 4-11, Comparative Example 4-1 to Comparative Example 4-3]
As the positive electrode mixture liquid, the battery electrode mixture liquids obtained in Examples 3-1 to 3-3, Example 3-5 to Example 3-12, and Comparative Example 3-1 to Comparative Example 3-3 were used. The positive electrode composite material layer (battery electrode composite material layer) was produced by using it. 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, the battery electrode mixture liquids obtained in Examples 3-15 to 3-18 and Comparative Examples 3-4 to 3-5 were used. A composite layer) was prepared. The evaluation results are shown in Table 1-4.
From Table 1-4, the battery electrode composite layers of Examples 4-1 to 4-15 have coating film appearances that are compared with the battery electrode composite layers of Comparative Examples 4-1 to 4-5. It was clear that the surface resistance of the coating film was excellent. In Comparative Examples 4-1 to 4-5, coating is difficult because the viscosity of the electrode mixture solution used is too high. Further, as a result of the large amount of polyvinyl alcohol functioning as an insulating component, It is considered that the resistance value has increased.

<Assembly of 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 solutions prepared previously (the positive electrode mixture solutions of Examples 3-1 to 3-3 and 3-5 to 3-12 and Comparative Examples 3-1 to 3-3) ) Is applied onto a 20 μm thick aluminum foil as a current collector using a doctor blade, dried at 120 ° C. under reduced pressure, and then rolled with a roller press to obtain a positive electrode composite having a thickness of 100 μm. A material layer was prepared. This is a punching working electrode with a diameter of 9 mm, a metallic lithium foil (thickness 0.15 mm) as a counter electrode, and a separator made of a porous polypropylene film (# 2400 manufactured by Celgard) is inserted and laminated between the working electrode and the counter electrode, An electrolyte solution (nonaqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1) was filled, and a bipolar electrode type metal cell (HS manufactured by Hosen Co., Ltd.) Flat cell). The cell was assembled in a glove box substituted with argon gas.

<Assembly of 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 liquids (negative electrode mixture liquids of Example 3-15 to Example 3-18 and Comparative Example 3-4 to Comparative Example 3-5) having a thickness of 20 μm serving as a current collector After apply | coating using a doctor blade on aluminum foil, after heat-drying at 120 degreeC under pressure reduction, it rolled by the roller press machine and produced the negative mix layer of thickness 100 micrometers. This is a punching working electrode with a diameter of 9 mm, a metallic lithium foil (thickness 0.15 mm) as a counter electrode, and a separator made of a porous polypropylene film (# 2400 manufactured by Celgard) is inserted and laminated between the working electrode and the counter electrode, An electrolyte solution (nonaqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1) was filled, and a bipolar electrode type metal cell (HS manufactured by Hosen Co., Ltd.) Flat cell). The cell was assembled in a glove box substituted with argon gas.

<Characteristic evaluation of lithium ion secondary battery positive electrode>
The prepared positive electrode evaluation cell was fully charged at a constant current and constant voltage charge (upper limit voltage 4.2 V) at a charge rate of 1.0 C using a charge / discharge device (SM-8 manufactured by Hokuto Denko) at 25 ° C. The charge / discharge for discharging to the discharge lower limit voltage of 3.0 V at a constant current at the same rate as the charge was defined as one cycle (charge / discharge interval pause time 30 minutes), and this cycle was performed for a total of 50 cycles to perform charge / discharge. . The cell after evaluation was disassembled in a glove box substituted with argon gas, and the appearance of the electrode coating film (the coating film appearance after 50 cycles) was visually confirmed. The evaluation criteria for the appearance of the coating film are ○ (very good) when no peeling from the current collector is observed and no change in the appearance, △ (good) when no change is observed in the appearance. A case where peeling of the composite material from the current collector was partially recognized was defined as x (defective). Further, the capacity retention ratio is a percentage of the discharge capacity at the 50th cycle with respect to the discharge capacity at the 1st cycle, and the closer the value is to 100%, the better. The evaluation results are shown in Table 1-5.

<Evaluation of lithium ion secondary battery negative electrode characteristics>
The prepared negative electrode evaluation cell was fully charged at a constant current and constant voltage charge (upper limit voltage 0.5 V) at a charge rate of 1.0 C using a charging / discharging device (SM-8 manufactured by Hokuto Denko) at 25 ° C. Charging / discharging is performed at a constant current at the same rate as during charging until the voltage reaches 1.5 V, and one cycle (charging / discharging interval pause time 30 minutes) is performed, and this cycle is performed for a total of 50 cycles. It was. The cell after evaluation was disassembled in a glove box substituted with argon gas, and the appearance of the electrode coating film (the coating film appearance after 50 cycles) was evaluated based on the same criteria as the positive electrode characteristic evaluation. The evaluation results are shown in Table 1-5.

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

From Table 1-5, it was found that Examples 5-1 to 5-15 had good coating film appearance and good capacity retention even after 50 charge / discharge cycles. On the other hand, Comparative Example 5-1 to Comparative Example 5-5 could not evaluate the positive electrode characteristics and the negative electrode characteristics because a good coating film could not be obtained.

<Examples relating to the second invention>
Hereinafter, the second invention will be mainly described in detail based on examples. However, the following examples are not necessarily related only to the second invention, but fall within the scope of the first invention and the third invention. If any, it can be referred to as an embodiment of these inventions. Moreover, this invention is not limited to a following example, unless the summary is exceeded. In this example, “part” represents “part by weight” and “%” represents “% by weight”.

Carbon black (sometimes abbreviated as “CB”), polyvinyl alcohol (sometimes abbreviated as “PVA”), organic dye derivative or triazine derivative (abbreviated as “pigment derivative”) used in Examples and Comparative Examples. The binder, the electrode active material, etc. are shown below. 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>
The same carbon black as that used in the examples relating to the first invention was used. Moreover, the measurement of the average primary particle diameter of carbon black was performed by the same method as the method demonstrated in the Example regarding 1st invention.

<Polyvinyl alcohol (resin containing general formula (A))>
Kuraray Poval PVA-505 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 73 mol%, average polymerization degree 500. Hereinafter, it is abbreviated as PVA-505.
Kuraray Poval PVA-105 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 98 mol%, average polymerization degree 500. Hereinafter, it is abbreviated as PVA-105.
Kuraray Poval LM-20 (manufactured by Kuraray): polyvinyl alcohol, saponification degree 40 mol%, average polymerization degree 200. Hereinafter, it is abbreviated as LM-20.
Synthetic product 1: polyvinyl alcohol, saponification degree 55 mol%, average polymerization degree about 500.
Synthetic product 2: polyvinyl alcohol, saponification degree 60 mol%, average polymerization degree about 500.
Synthetic product 3: amino group-modified polyvinyl alcohol, saponification degree 76 mol%, modified group amount 10 mol%, average polymerization degree 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 92 mol%, average degree of polymerization about 100.
Synthetic product 6: polyvinyl alcohol, saponification degree 72 mol%, average polymerization degree about 100.
-Synthetic product 7: Polyvinyl alcohol, saponification degree 70 mol%, average degree of polymerization about 1500.
Synthetic products 1 to 7 were obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the industry.

<Polyvinyl acetal>
ESREC BH-3 (manufactured by Sekisui Chemical Co., Ltd.): polyvinyl butyral resin, hydroxyl group 34 mol%, butyralization degree 65 mol%, calculated molecular weight 110000. Hereinafter, it is abbreviated as BH-3.
ESREC KS-1 (manufactured by Sekisui Chemical Co., Ltd.): polyvinyl acetoacetal resin, hydroxyl group 25 mol%, acetalization degree 74 mol%, calculated molecular weight 27000. Hereinafter, it is abbreviated as KS-1.
Vinylec H (manufactured by JNC): polyvinyl formal resin, hydroxyl group of about 13 mol%, 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 the general formula (A) contained in the polymer chain of polyvinyl acetal.

<Acid pigment derivative>
The structures of organic dye derivatives having acidic functional groups are shown in Table 2-1.

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

<Basic pigment derivative>
The structure of the organic dye derivative having a basic functional group is shown in Table 2-3.

The structures of triazine derivatives having basic functional groups are shown in Table 2-4.

<Binder>
The binder used was the same as that used in the examples relating to the first invention.

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

<Active material>
HLC-22 (Honjo Chemical Co., Ltd.): positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle size 6.6 μm, specific surface area 0.62 m ² / g. Hereinafter, abbreviated as LCO.
Artificial graphite: negative electrode active material, average particle size 18 μm. Hereinafter, it is abbreviated as graphite.

<Evaluation of carbon black dispersion>
The carbon black dispersions obtained in the examples and comparative examples are evaluated by measuring the viscosity (its storage stability) and the average particle size after dispersion (its storage stability) according to the method described in the first invention. It went by. However, the storage stability of the viscosity was evaluated from the change in viscosity value after the carbon black dispersion was stored at 60 ° C. for 10 days. The smaller the change, the better the stability. The storage stability of the average particle diameter after dispersion was evaluated from the change in D50 value after the carbon black dispersion was stored at 60 ° C. for 10 days. The smaller the change, the better the stability.

<Preparation of carbon black dispersion by media dispersion>
(Carbon black dispersion using polyvinyl alcohol with different saponification degrees)
[Example 1-1 to Example 1-3]
In accordance with the composition shown in Table 2-5, NMP, various polyvinyl alcohols, and various pigment derivatives were charged into a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, then carbon black was added, and 1.25 mmφ zirconia beads were used as a medium for painting. Each carbon black dispersion was obtained by dispersing for 2 hours with a conditioner. In all cases, the viscosity was low, the D50 value was small, and the storage stability was good.

<Preparation of carbon black dispersion containing binder>
(Carbon black dispersion using polyvinyl alcohol with different saponification degrees)
[Example 2-1 to Example 2-8, Example 2-14 to Example 2-15]
In accordance with the composition shown in Table 2-6, NMP, various polyvinyl alcohols, various pigment derivatives, and PVDF were charged into a glass bottle, mixed thoroughly, dissolved, or mixed and dispersed, then added with carbon black, and dispersed with a homogenizer for 1 hour. A black dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability. Moreover, it became clear that the presence or absence of the modification | denaturation of polyvinyl alcohol does not have big influence on the performance as a dispersing agent.

[Example 2-16]
According to the composition shown in Table 2-6, NMP, polyvinyl alcohol, and a pigment derivative were charged into a glass bottle and thoroughly mixed and dissolved. Next, a powder mixture in which carbon black and PVDF were homogeneously mixed was prepared, and this was added to the NMP solution of the dispersant prepared in advance. Then, it disperse | distributed for 1 hour with the homogenizer, and obtained the carbon black dispersion liquid. There were no coarse particles, the viscosity was low, and the storage stability was good.

[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 dispersed with a homogenizer for 1 hour. Each carbon black dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Example 2-19 to Example 2-20]
In accordance with the composition shown in Table 2-6, NMP, polyvinyl alcohol, pigment derivative and # 7300 were charged in a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, and then carbon black was added and dispersed with a homogenizer for 1 hour. A dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Comparative Examples 2-1 to 2-10]
In accordance with the composition shown in Table 2-6, NMP, various polyvinyl alcohols or various polyvinyl acetal resins, various pigment derivatives and PVDF were charged into a glass bottle, and thoroughly mixed, dissolved, or mixed, and then carbon black was added. Each carbon black dispersion was obtained by dispersing for 1 hour.
However, it was revealed that the obtained dispersion was in a high viscosity state regardless of the type of pigment derivative, and the carbon black and binder concentrations could not be further improved.
Further, in Comparative Examples 2-1 to 2-2 and Comparative Examples 2-6 to 2-7, all of them are in a significantly high viscosity state and have a large D50 value. It was found that they could not be dispersed. Further, from these results, when polyvinyl alcohol having a saponification degree of less than 50 mol% or more than 95 mol% and a pigment derivative are used as a dispersant, the desired high concentration and low viscosity carbon black dispersion is obtained. It became clear that the liquid could not be obtained.

From Table 2-6, when a resin that can be dissolved or dispersed in NMP is used as a binder, the properties of the obtained carbon black dispersion are as follows when the dispersion is prepared without adding the binder of Table 2-5. Similarly, it can be seen that a dispersion having high concentration and low viscosity and good storage stability can be obtained.

(Carbon black dispersion using different types of carbon black)
[Example 2-9 to Example 2-13]
In accordance with the composition shown in Table 2-6, NMP, polyvinyl alcohol, pigment derivative and PVDF were charged into a glass bottle, mixed and dissolved or mixed and dispersed, then various carbon blacks were added and dispersed with a homogenizer for 1 hour. A dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

(Carbon black dispersion using different types of pigment derivatives)
[Example 3-1 to Example 3-20]
In accordance with the composition shown in Table 2-7, NMP, polyvinyl alcohol, various pigment derivatives, and PVDF were charged into a glass bottle, mixed and dissolved, or mixed and dispersed. Carbon black was added and dispersed with a homogenizer for 1 hour. A dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability. Further, among these, it was found that a particularly good dispersion can be obtained when a triazine derivative is used.

[Comparative Example 3-1]
In accordance with the composition shown in Table 2-7, NMP, polyvinyl alcohol, 1,2,3,4-benzenetetracarboxylic acid (D-01), and PVDF were charged into a glass bottle and thoroughly mixed and dissolved or mixed and dispersed. Black was added and dispersed with a homogenizer for 1 hour to obtain each carbon black dispersion. The obtained liquid was in a remarkably high viscosity state and had a large D50 value, indicating that carbon black could not be sufficiently dispersed.

(Carbon black dispersions with different polyvinyl alcohol contents)
[Example 4-1 to Example 4-9]
In accordance with the composition shown in Table 2-8, NMP, polyvinyl alcohol, various pigment derivatives, and PVDF were charged into a glass bottle, mixed and dissolved, or mixed and dispersed. Carbon black was added and dispersed with a homogenizer for 1 hour. A dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Comparative Example 4-1]
In accordance with the composition shown in Table 2-8, NMP, polyvinyl alcohol, pigment derivative, and PVDF are charged into a glass bottle, mixed and dissolved or mixed and dispersed, and then carbon black is added and dispersed with a homogenizer for 1 hour. A liquid was obtained. The obtained liquid was in a remarkably high viscosity state and had a large D50 value, indicating that carbon black could not be sufficiently dispersed.

<Preparation of carbon black dispersion containing positive electrode active material or negative electrode active material>
[Example 5-1 to Example 5-23]
According to 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 3-16 To the carbon black dispersions containing the binders obtained in Example 3-17, Example 4-1 to Example 4-7, and Example 4-9, LCO as the positive electrode active material was charged and dispersed with a disper. Mix well to obtain each mixture. Since the carbon black dispersion used had a low viscosity, a large amount of LCO could be added, and the resulting mixture was also in a low viscosity state.

[Example 5-24]
According to the composition shown in Table 2-9, 2.7 parts of HS-100, 1.25 parts of PVDF, 0.011 part of polyvinyl alcohol, 0.043 part of pigment derivative, and 63 parts of LCO were mixed homogeneously. After preparing the powder mixture, half of the total amount of the powder mixture was added to 32.996 parts of NMP, and the mixture was processed with a planetary mixer for 30 minutes. 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. A carbon black dispersion containing LCO as an active material was obtained. The obtained liquid was in a low viscosity state as in Example 5-23.

[Examples 5-25 to 5-28]
In accordance with the composition shown in Table 2-9, graphite as a negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Example 2-2 to Example 2-5, and thoroughly mixed with a disper. Each liquid mixture was obtained. Since the carbon black dispersion used had a low viscosity, a large amount of graphite could be added, and the resulting mixture was also in a low viscosity state.

[Comparative Examples 5-1 to 5-5]
According to the composition shown in Table 2-9, carbon black dispersion containing binders obtained in Comparative Example 2-3, Comparative Example 2-5, Comparative Example 2-8, Comparative Example 2-10, and Comparative Example 4-1. The liquid was charged with LCO as a positive electrode active material and mixed well with a disper to obtain each liquid mixture. In any case, since the viscosity value of the carbon black dispersion used is high, the increase in the viscosity value when LCO is added is larger than in Examples 5-1 to 5-23, and the stability is high. The increase in viscosity in the evaluation test was also large.

[Comparative Examples 5-6 to 5-8]
In accordance with the composition shown in Table 2-9, graphite as a negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Example 2-8, Comparative Example 2-10, and Comparative Example 4-1. The mixture was sufficiently mixed with a disper to obtain each mixture. In any case, since the viscosity value of the carbon black dispersion used is high, the increase in the viscosity value when graphite is added is larger than in Examples 5-25 to 5-28, and the stability is increased. The increase in viscosity in the evaluation test was also large.

<Preparation of battery electrode composite layer>
Using the carbon black dispersion liquid 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 liquid, a battery electrode mixture layer was prepared according to the method described in the first invention. The evaluation was performed. When the surface resistance is not measurable, no value is given (−), and “△” in the appearance of the coating means “spotted (possible)”.

[Example 6-1 to Example 6-21, Comparative Example 6-1 to Comparative Example 6-3]
As the positive electrode mixture liquid, Examples 5-1 to 5-6, Examples 5-8 to 5-14, Examples 5-16 to 5-23, Comparative Example 5-2, and Comparison Using the battery electrode mixture liquid obtained in Examples 5-4 to 5-5, a positive electrode mixture layer (battery electrode mixture layer) was produced. 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 liquid, using the battery electrode mixture liquid obtained in Example 5-25 to Example 5-26, Example 5-28, and Comparative Example 5-7 to Comparative Example 5-8, A negative electrode mixture layer (battery electrode mixture layer) was produced. The evaluation results are shown in Table 2-10.
As shown in Table 2-10, the battery electrode composite layers of Examples 6-1 to 6-24 have a coating film appearance as compared with the battery electrode composite layers of Comparative Examples 6-1 to 6-5. It was clear that the surface resistance of the coating film 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. Further, in Comparative Examples 6-3 and 6-5, a large amount is used. As a result of the contained dispersant functioning as an insulating component, the surface resistance value is considered to have increased.

<Assembly of 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 previously prepared battery electrode mixture liquids (Examples 5-1 to 5-6, Examples 5-8 to 5-14, Examples 5-16 to 5-23, Comparative Example 5) 2 and the positive electrode mixture liquids of Comparative Examples 5-4 to 5-5) were assembled according to the method described in the first invention.

<Assembly of lithium ion secondary battery negative electrode evaluation cell>
[Examples 7-22 to 7-24, Comparative Examples 7-4 to 7-5]
Using the previously prepared battery electrode mixture liquids (negative electrode mixture liquids of Example 5-25 to Example 5-26, Example 5-28, and Comparative Example 5-7 to Comparative Example 5-8), A negative electrode evaluation cell was assembled according to the method described in the first invention. However, copper foil was used instead of aluminum foil as a current collector.

<Characteristic evaluation of lithium ion secondary battery positive electrode>
The 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 could not be obtained due to peeling or short-circuiting of the coating film from the current collector and the capacity could not be obtained, no value was given (−). The evaluation results are shown in Table 2-11.

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

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

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 good even after 50 charge / discharge cycles. On the other hand, Comparative Examples 7-1 to 7-5 could not evaluate the positive electrode characteristics and the negative electrode characteristics because a good coating film could not be obtained.

<Examples relating to the third invention>
Hereinafter, the third invention will be described in detail based on examples. However, the following examples are not necessarily related only to the third invention, and may be within the scope of the first invention and the second invention. Reference can also be made to examples of these inventions. Moreover, this invention is not limited to a following example, unless the summary is exceeded. In this example, “part” represents “part by weight” and “%” represents “% by weight”.

<Carbon black>
# 850 (manufactured by Mitsubishi Chemical Corporation): furnace black, average primary particle size 17 nm, specific surface area 220 m ² / g. Hereinafter, it is abbreviated as # 850.
# 2600 (manufactured by Mitsubishi Chemical Corporation): furnace black, average primary particle size 13 nm, specific surface area 370 m ² / g. Hereinafter, it is abbreviated as # 2600.
Ketjen black EC-300J (manufactured by Akzo): hollow carbon black, average primary particle size 40 nm, specific surface area 800 m ² / g. Hereinafter, it is abbreviated as 300J.
Ketjen black EC-600JD (manufactured by Akzo): hollow carbon black, average primary particle size 34 nm, specific surface area 1270 m ² / g. Hereinafter, it is abbreviated as 600 JD.
In addition, the measurement of the average primary particle diameter of carbon black was performed by the same method as the method demonstrated in the Example regarding 1st invention.

<Polyvinyl alcohol>
Kuraray Poval PVA-505 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 73 mol%, average polymerization degree 500. Hereinafter, it is abbreviated as PVA-505.
Kuraray Poval PVA-205 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 88 mol%, average polymerization degree 500. Hereinafter, it is abbreviated as PVA-205.
Goosephimer LL-02 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.): polyvinyl alcohol, saponification degree 50 mol%, average polymerization degree 1000 or less. Hereinafter, abbreviated as LL-02.
Synthetic product 1: polyvinyl alcohol, saponification degree 60 mol%, average polymerization degree about 500.
Synthetic product 2: polyvinyl alcohol, saponification degree 85 mol%, average polymerization degree about 500.
Synthetic product 3: polyvinyl alcohol, saponification degree 72 mol%, average polymerization degree about 100.
-Synthetic product 4: Polyvinyl alcohol, saponification degree 70 mol%, average degree of polymerization about 1500.
The synthetic product 1, the synthetic product 2, the synthetic product 3, and the synthetic product 4 were obtained by saponifying polyvinyl acetate with sodium hydroxide by a method known in the industry.

<Active material>
HLC-22 (Honjo Chemical Co., Ltd.): positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle size 6.6 μm, specific surface area 0.62 m ² / g. Hereinafter, abbreviated as LCO.
Artificial graphite: negative electrode active material, average particle size 12 μm. Hereinafter, it is abbreviated as graphite.

<Evaluation of carbon black dispersion>
The carbon black dispersions obtained in the examples and comparative examples are evaluated by measuring the viscosity (its storage stability) and the average particle size after dispersion (its storage stability) according to the method described in the first invention. It went by. However, the storage stability of the viscosity was evaluated from the change in viscosity value after the carbon black dispersion was stored at 60 ° C. for 10 days or at 50 ° C. for 15 days. The smaller the change, the better the stability. The storage stability of the average particle diameter after dispersion was evaluated from the change in D50 value after the carbon black dispersion was stored at 60 ° C. for 10 days or at 50 ° C. for 15 days. . The smaller the change, the better the stability.

<Preparation of carbon black dispersion>
(Carbon black dispersion using polyvinyl alcohol with different saponification degrees)
[Example 1-1 to Example 1-8]
In accordance with the composition shown in Table 3-1, NMP and various polyvinyl alcohols were charged into a glass bottle, mixed and dissolved or mixed and dispersed, then various carbon blacks were added, and 1.25 mmφ zirconia beads were used as media and 2 Each carbon black dispersion was obtained by time dispersion. In all cases, the viscosity was low, the D50 value was small, and the storage stability was good.

[Comparative Example 1-1 to Comparative Example 1-3, Reference Example 1-1]
In accordance with the composition shown in Table 3-1, NMP and various polyvinyl alcohols were charged into a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, and then carbon black was added. Distributed. However, all of the obtained dispersions are in a very high viscosity state, and the D50 value is large, indicating that the carbon black cannot be sufficiently dispersed. From this result, it was revealed that when a polyvinyl alcohol having a saponification degree of less than 60 mol% or more than 85 mol% is used, a desired high concentration and low viscosity carbon black dispersion cannot be obtained. It is also clear that the desired high-concentration and low-viscosity carbon black dispersion cannot be obtained even when the amount of polyvinyl alcohol as a dispersant is excessively large or insufficient with respect to carbon black. It was.

<Preparation of carbon black dispersion containing binder>
[Example 2-1 to Example 2-15]
In accordance with the composition shown in Table 3-2, NMP, various polyvinyl alcohols and various binders are charged into a glass bottle, and after thoroughly mixing, dissolving or mixing, various carbon blacks are added and dispersed with a homogenizer for 1 hour. A liquid was obtained. All of them had no coarse particles, had a 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 charged into a glass bottle and mixed and dissolved or dispersed sufficiently. Thereafter, carbon black obtained by mixing # 850 and 300J at a weight ratio of 1: 1, or carbon black obtained by mixing 300J and 600JD at a weight ratio of 1: 1, was added, and dispersed with a homogenizer for 1 hour. Each carbon black dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Example 2-18]
According to the composition shown in Table 3-2, NMP and polyvinyl alcohol were charged into a glass bottle and thoroughly mixed and dissolved. Next, a powder mixture in which carbon black and PVDF were homogeneously mixed was prepared, and this was added to an NMP solution of polyvinyl alcohol prepared in advance. Then, it disperse | distributed for 1 hour with the homogenizer, and obtained the carbon black dispersion liquid. There were no coarse particles, the viscosity was low, and the storage stability was good.

[Example 2-19]
According to the composition shown in Table 3-2, 57 parts of the carbon black dispersion liquid of Example 1-2, 6 parts of PVDF and 37 parts of NMP were added to a glass bottle and dispersed with a homogenizer for 1 hour to obtain each carbon black dispersion liquid. It was. All of them had no coarse particles, had a low viscosity, and had good storage stability.

[Comparative Examples 2-1 to 2-3, Reference Example 2-1]
In accordance with the composition shown in Table 3-2, NMP, various polyvinyl alcohols and PVDF are charged into a glass bottle, and after thoroughly mixing, dissolving or mixing, carbon black is added and dispersed for 1 hour with a homogenizer. Got. However, it was revealed that the viscosity of the obtained dispersion was as high as that prepared without adding a binder, and the carbon black and binder concentrations could not be further improved.

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

<Preparation of carbon black dispersion containing positive electrode active material or negative electrode active material>
[Example 3-1 to Example 3-14]
In accordance with the composition shown in Table 3-3, the carbon black dispersion containing the binder obtained in Example 2-1 to Example 2-14 was charged with LCO as the positive electrode active material and thoroughly mixed with a disper, Each mixture was obtained. Since the carbon black dispersion used had a low viscosity, a large amount of LCO could be added, and the resulting mixture was also in a low viscosity state.

[Example 3-15]
After preparing a powder mixture with 1.71 parts of granular product, 2.56 parts of PVDF, 0.26 part of PVA-505, 56.7 parts of LCO and homogeneously mixed, 38.77 parts of NMP Half of the total amount of the powder mixture was added and treated 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. A carbon black dispersion containing LCO as an active material was obtained. The obtained liquid was in a low viscosity state as in Example 3-2.

[Example 3-16 to Example 3-20]
In accordance with the composition shown in Table 3-3, graphite as a negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Examples 2-1 to 2-4 and Example 2-7. The mixture was sufficiently mixed with a disper to obtain each mixture. Since the carbon black dispersion used had a low viscosity, a large amount of graphite could be added, and the resulting mixture was also in a low viscosity state.

[Comparative Examples 3-1 to 3-4]
In accordance with the composition shown in Table 3-3, LCO as a positive electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Example 2-1 to Comparative Example 2-3 and Reference Example 2-1. The mixture was sufficiently mixed with a disper to obtain each mixture. In any case, since the viscosity value of the carbon black dispersion used was high, the increase in the viscosity value when LCO was added was larger than that in Examples 3-1 to 3-14, and the carbon black dispersion was remarkably high. It was in a viscous state.

[Comparative Examples 3-5 to 3-7]
In accordance with the composition shown in Table 3-3, graphite as the negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Examples 2-1 to 2-3, and thoroughly mixed with a disper. Each liquid mixture was obtained. In any case, since the viscosity value of the carbon black dispersion used is high, the increase in the viscosity value when graphite is added is larger than that in Examples 3-16 to 3-20, and it is remarkably high. It was in a viscous state.

<Preparation of battery electrode composite layer>
Using the carbon black dispersion liquid 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 liquid, a battery electrode mixture layer was prepared according to the method described in the first invention. The evaluation was performed. In the appearance of the coating film, “Δ” means “with spotted pattern (possible)”. When the appearance of the coating film was extremely poor and could not be measured, no value was given (−).

[Example 4-1 to Example 4-14, Comparative Example 4-1 to Comparative Example 4-3]
Using the battery electrode mixture liquids obtained in Examples 3-1 to 3-14 and Comparative Examples 3-1 to 3-3 as the positive electrode mixture liquid, the positive electrode mixture layer (battery electrode) A composite layer) was prepared. 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]
Using the battery electrode mixture liquids obtained in Examples 3-16 to 3-20 and Comparative Examples 3-5 to 3-7 as the negative electrode mixture liquid, the negative electrode mixture layer (battery electrode) A composite layer) was prepared. The evaluation results are shown in Table 3-4.

From Table 3-4, the battery electrode composite layers of Examples 4-1 to 4-19 have an appearance of the coating film as compared with the battery electrode composite layers of Comparative Examples 4-1 to 4-6. It was clear that the surface resistance of the coating film was excellent. In Comparative Examples 4-1 to 4-6, the viscosity of the electrode mixture solution used was too high to be applied, and in Comparative Examples 4-3 and 4-6, a large amount As a result of the contained polyvinyl alcohol functioning as an insulating component, the surface resistance value is considered to have increased.

<Assembly of lithium ion secondary battery positive electrode evaluation cell>
[Example 5-1 to Example 5-14, Comparative Example 5-1 to Comparative Example 5-3]
Using the previously prepared battery electrode mixture liquids (the positive electrode mixture liquids of Examples 3-1 to 3-14 and Comparative Examples 3-1 to 3-3), the first invention will be described. A positive electrode evaluation cell was assembled according to the method described above.

<Assembly of lithium ion secondary battery negative electrode evaluation cell>
[Examples 5-15 to 5-19, Comparative Example 5-4 to Comparative Example 5-6]
Using the previously prepared battery electrode mixture liquids (negative electrode mixture liquids of Examples 3-16 to 3-20 and Comparative Examples 3-5 to 3-7), the first invention will explain A negative electrode evaluation cell was assembled according to the method described above. However, copper foil was used instead of aluminum foil as a current collector.

<Characteristic evaluation of lithium ion secondary battery positive electrode>
The 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 could not be obtained due to peeling or short-circuiting of the coating film from the current collector and the capacity could not be obtained, no value was given (−). The evaluation results are shown in Table 3-5.

<Evaluation of lithium ion secondary battery negative electrode characteristics>
According to the method described in the first invention, negative electrode characteristics were evaluated. 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 and constant voltage charging was not set to 0.5V, but the lower limit voltage was set to 0.5V. The evaluation results are shown in Table 3-5.

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

Claims

A carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and N-methyl-2-pyrrolidone as a solvent, wherein the saponification degree of polyvinyl alcohol is 60 to 85 mol%, When the BET specific surface area of Xm 2 / g and the amount of polyvinyl alcohol added to 1 g of carbon black is aXg, a is in the range of 0.00017 ≦ a ≦ 0.00256, and polyvinyl alcohol relative to 100 parts by weight of carbon black The carbon black dispersion liquid is characterized in that 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 a triazine derivative, or polyvinyl alcohol and an organic dye derivative as a dispersant, and N-methyl-2-pyrrolidone as a solvent, and having a carbon black weight of 100 Carbon is characterized in that the total amount of the dispersant is 50 parts by weight or less with respect to parts, and the polyvinyl alcohol contains 50 to 95 mol% of repeating units represented by the following general formula (A) in the polymer chain. Black dispersion.
Formula (A)
3. The carbon black dispersion according to claim 2, wherein the dispersant is polyvinyl alcohol and a triazine derivative.
4. The carbon black dispersion according to claim 2, wherein the polyvinyl alcohol contains 55 to 85 mol% of the repeating unit represented by the general formula (A) in the polymer chain.
The carbon black dispersion according to any one of claims 2 to 4, wherein the total amount of the dispersant is from 0.5 parts by weight to 40 parts by weight with respect to 100 parts by weight of the carbon black.
The carbon black dispersion according to any one of claims 2 to 5, wherein the polyvinyl alcohol is from 0.2 parts by weight to 20 parts by weight with respect to 100 parts by weight of the carbon black.
The carbon black dispersion according to any one of claims 2 to 5, wherein the polyvinyl alcohol is 0.2 to 8 parts by weight with respect to 100 parts by weight of carbon black.
A carbon black dispersion comprising carbon black, polyvinyl alcohol as a dispersant, and N-methyl-2-pyrrolidone as a solvent, wherein the saponification degree of polyvinyl alcohol is 60 to 85 mol%, A carbon black dispersion characterized by having a BET specific surface area of 30 to 1500 m 2 / g and a polyvinyl alcohol content of more than 8 parts by weight and 40 parts by weight or less based on 100 parts by weight of carbon black.
The carbon black dispersion according to claim 8, wherein 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.
The carbon black dispersion according to claim 8 or 9, wherein the carbon black has a BET specific surface area of 200 to 1500 m 2 / g.
The carbon black dispersion according to claim 8 or 9, wherein the carbon black has a BET specific surface area of 500 to 1500 m 2 / g.
12. The carbon black dispersion according to claim 8, wherein the carbon black is hollow carbon black.
The carbon black dispersion according to any one of claims 8 to 12, wherein the polyvinyl alcohol is 0.05 parts by weight or more and less than 2 parts by weight with respect to 100 parts by weight of the total solid components contained in the dispersion. .
A carbon black dispersion for a battery comprising the carbon black dispersion according to any one of claims 1 to 13 and further containing a positive electrode active material or a negative electrode active material.
A battery electrode composite layer formed by applying the carbon black dispersion according to any one of claims 1 to 13 or 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 the positive electrode and the negative electrode are at least A lithium ion secondary battery, one of which comprises the battery electrode mixture layer according to claim 15.