JP5601416B1 - Carbon black dispersion and use thereof - Google Patents

Abstract

Disclosed is a carbon black dispersion using N-methyl-2-pyrrolidone as a solvent, which is superior in dispersibility and storage stability at a low viscosity and high concentration as compared with conventional resin-type dispersants. The present invention also provides a battery electrode mixture layer having a uniform and good coating film property and low surface resistance, and a lithium ion secondary battery comprising the same.
A carbon black dispersion containing carbon black, polyvinyl alcohol and a triazine derivative, or polyvinyl alcohol and an organic pigment derivative as a dispersant, and N-methyl-2-pyrrolidone as a solvent, The total amount of polyvinyl alcohol and triazine derivative or polyvinyl alcohol and organic pigment derivative as a dispersant for 100 parts by weight of carbon black is 50 parts by weight or less, and polyvinyl alcohol has 50 to 50 repeating units in the polymer chain. Carbon black dispersion characterized by containing 95 mol%.
[Selection figure] None

Description

  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.
Since these requirements have a great influence on the cost of the solvent and the energy used during drying, the more expensive the solvent used or the higher the boiling point of 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 above-mentioned 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) It is described that a positive electrode plate with good adhesion can be produced using the performance as a dispersant possessed by a pigment derivative-type dispersant. In particular, when the oxazine derivative is used as a pigment derivative-type dispersant and polyvinyl butyral is used as a resin-type dispersant in combination in a specific ratio range, the balance between the viscosity and adhesion of the positive electrode mixture liquid can be achieved. Have been described.
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 are not stable. Therefore, the resistance to non-aqueous electrolyte is higher, the coating film properties of the obtained coating film are stable, and in the 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 the 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 dispersant and N-methyl-2-pyrrolidone as one solvent. However, the physical and chemical properties of the carbon black, solvent type, and dispersant used are closely related to each other. However, when using a specific solvent called N-methyl-2-pyrrolidone, 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 and does not function as a dispersant. Furthermore, the same applies to polyvinyl esters such as polyvinyl acetate as a precursor raw 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 specific example has been reported, and a specific solvent called N-methyl-2-pyrrolidone, polyvinyl alcohols, and organic dye derivatives or triazine derivatives (hereinafter collectively referred to as pigment derivatives) are used as dispersants. How the physical and chemical properties of carbon black, polyvinyl alcohol and pigment derivatives, and their quantitative relationship, affect the carbon black dispersion, battery electrode composite layer, and battery characteristics. In fact, it has not been studied at all.

Moreover, generally, when manufacturing the electrode for lithium ion secondary batteries, the solvent used for preparation of an electrode compound liquid is determined by the polymer material used for the binder in a battery. At present, 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. Another object of the present invention is to provide a battery electrode mixture layer having uniform and good coating film properties, low surface resistance, good resin-type dispersant resistance to non-aqueous electrolyte, and stable coating film properties. is there.

  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, carbon black, an organic pigment derivative or a triazine derivative, There is a critical range that greatly contributes to dispersibility between the use amount of the polyvinyl alcohol having the repeating unit represented by the general formula (A) in a specific ratio in the polymer chain, and these are constant. Carbon black dispersion with high concentration, low viscosity, and good long-term storage stability can be produced, and the surface resistance is low, and the resistance of the dispersant to non-aqueous electrolyte is good. The inventors have found that a battery electrode mixture layer 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 pigment derivative as a dispersant, and N-methyl-2-pyrrolidone as a solvent. The total amount of polyvinyl alcohol and triazine derivative or polyvinyl alcohol and organic pigment derivative as the dispersant with respect to 100 parts by weight of the carbon black is 50 parts by weight or less, and the polyvinyl alcohol is The present invention relates to a carbon black dispersion characterized by containing 50 to 95 mol% of a repeating unit represented by formula (A) in a polymer chain.

Formula (A)

 An embodiment of the present invention also relates to the carbon black dispersion, wherein the dispersant is the 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. .

 Further, in an embodiment of the present invention, the total amount of polyvinyl alcohol and triazine derivative, or the total amount of polyvinyl alcohol and organic pigment derivative is 0.5 parts by weight or more and 40 parts by weight with respect to 100 parts by weight of carbon black. It is related with the said carbon black dispersion liquid characterized by being below a part.

 Moreover, the embodiment of the present invention relates to the carbon black dispersion, wherein the polyvinyl alcohol is 0.2 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the carbon black.

 Moreover, the embodiment of the present invention relates to the carbon black dispersion, wherein the polyvinyl alcohol is 0.2 parts by weight or more and 8 parts by weight or less with respect to 100 parts by weight of the carbon black.

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

 An embodiment of the present invention also 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.

  According to the present invention, it is possible to obtain a coating film having better adhesion to a coating substrate than when a conventionally known pigment derivative type dispersing agent is used alone, and a conventionally known resin type dispersing agent can be used alone or A carbon black dispersion having a significantly lower viscosity than that obtained when an organic dye derivative is used in combination can be obtained, and the carbon black concentration can be increased while maintaining adhesion. As a result, a carbon black dispersion with a higher concentration than before can be provided, and the amount of N-methyl-2-pyrrolidone solvent used can be greatly reduced, and the drying process of the coated film can be greatly shortened. You will be able to In addition, 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.

  Details of the present invention will be described below. In this specification, “carbon black dispersion” and “carbon black dispersion for battery” are referred to as “dispersion”, “organic pigment derivative or triazine derivative” as “pigment derivative”, and “polyvinyl alcohol and pigment derivative”. “Dispersant” and “N-methyl-2-pyrrolidone” are sometimes abbreviated as “NMP”.

<Carbon black>
As the carbon black used in the present invention, various types such as commercially available furnace black, channel black, thermal black, acetylene black, ketjen black and the like can be used. Ordinarily oxidized carbon black, hollow carbon black, graphitized carbon black, carbon nanotube, carbon nanofiber, and the like can also be used.

  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 carbon black used in the present invention is not particularly limited, but industrially produced carbon black such as acetylene black and furnace black is preferably used.

  Further, the average primary particle diameter of carbon black used in the production of the dispersion is preferably 0.01 to 1 μm, particularly in the range of the average primary particle diameter of carbon black used in general dispersions and paints. 0.01 to 0.2 μm is preferable, and 0.01 to 0.1 μm is more preferable. 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.

  As other physical property values representing the physical characteristics of carbon black, BET specific surface area and pH are known. 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.

<Polyvinyl alcohol>
In the present invention, polyvinyl alcohol is used as the 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 the polyvinyl alcohol used by this invention, Hereinafter, the polyvinyl alcohol obtained by saponifying this from polyvinyl acetate is described.
In general, 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.
In addition, the saponification degree in this invention represents the ratio (mol%) of the repeating unit represented by general formula (A) contained in polyvinyl alcohol. For example, in the case of polyvinyl alcohol obtained by saponifying polyvinyl acetate, the number of hydroxyl groups derived from the vinyl alcohol skeleton contained in the polyvinyl alcohol, the number of acetyl groups derived from the vinyl acetate skeleton and the number of hydroxyl groups derived from the vinyl alcohol skeleton The value divided by the sum of

  The polyvinyl alcohol used in the present invention is mainly polyvinyl alcohol obtained by saponifying polyvinyl ester, particularly polyvinyl acetate, but is 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 polyvinyl alcohol having a saponification degree of 50 to 95 mol% used in the present invention, and these can be used alone or in combination of two or more.

  Polyvinyl alcohol as a dispersant preferably has an average degree of polymerization of 50 to 4000, more preferably 100 to 3000, particularly preferably 100 to 2000, and still more preferably 100 to 1500. 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.

  Those having a saponification degree of less than 50 mol% are very good in solubility in NMP, but are considered to be ineffective for dispersion due to poor adsorption to carbon black, and those having a saponification degree of more than 95 mol% Since it hardly dissolves or swells in NMP, even if it is adsorbed to carbon black, the polymer chain cannot be extended to the NMP side, and therefore it is presumed that steric repulsion cannot be effectively performed. . On the other hand, those having a saponification degree of 50 to 95 mol% 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.), Denka Poval (manufactured by Denki Kagaku Kogyo Co., Ltd.), J -Various grades can be obtained from the market under trade names such as POVAL (Nippon Vinegar-Poval).

  More specifically, Kuraray Poval PVA-403 (degree of saponification of 78.5 to 81.5 mol%, average degree of polymerization of 300, 4% aqueous solution viscosity at 20 ° C. according to JIS K6726 2.8 to 3.3 mPa · s ), Kuraray Poval PVA-505 (degree of saponification 72.5-74.5 mol%, average polymerization degree 500, 4% aqueous solution viscosity 4.2-5.0 mPa · s), Kuraray Poval L-8, Kuraray Poval L-9 Kuraraypoval L-9-78, Kuraraypoval L-10, Kuraraypoval C-506, Kuraraypoval KL-506, Gohsenol KL-03 (78.5-82.0 mol%, average polymerization degree 500 or less, 4% Aqueous solution viscosity 2.8-3.4 mPa · s), KL-05 (78.5-82.0 mol%, average polymerization degree 1000 or less, 4% aqueous solution viscosity 4.0) 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 degree 1000 or less, 4% aqueous solution viscosity 6.0-8.0 mPa · s) and the like, but are not limited thereto.

<Pigment derivative>
First, the pigment derivative used in the present invention will be described. The pigment derivative used in the present invention 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 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, Z represents —SO ₃ M, —COOM, -P (O) (-OM) ₂ or -O-P (O) (-OM) ₂ , M represents one equivalent of a 1 to 3 valent cation, and Q represents -O-R ² , —NH—R ² , a halogen group, —X ¹ —R ¹ or —X ² —Y—Z, wherein R ² represents a hydrogen atom or an alkyl group which may have a substituent. Or the alkenyl group which may have a substituent is represented. 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 —CH ₂ NHCOCH ₂ NH—, wherein R ³ and R ⁴ are each independently an organic dye residue, a heterocyclic residue which may have a substituent, or an aromatic which may have a substituent. Represents a group ring residue or —Y—Z, and Y and Z have the same meanings as Y and Z in formula (1). ]

In the above, examples of the organic dye residue in R ¹ , R ³ and R ⁴ include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, phthalocyanine dyes, anthraquinones, diaminodianthraquinones, anthra Anthraquinone dyes such as pyrimidine, flavantron, anthanthrone, indanthrone, pyranthrone, violanthrone, quinacridone dye, dioxazine dye, perinone dye, perylene dye, thioindigo dye, isoindoline dye, isoindolinone Residues such as dyes, quinophthalone dyes, selenium dyes, metal complex dyes, etc. 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.

In the above, 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, and benzimidazole. Examples thereof include heterocyclic residues such as lone, benzthiazole, 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 1 to 3 valent cations, 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. Moreover, when R < ⁵ >, R < ⁶ >, R < ⁷ >, R < ⁸ > has a carbon atom, carbon number is 1-40, Preferably it is 1-30, More preferably, it is 1-20.

  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.

［Ｘ⁸は、直接結合、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＣＨ₂ＮＨＣＯＣＨ₂ＮＨ−、−Ｘ⁹−Ｙ−または−Ｘ⁹−Ｙ−Ｘ¹⁰−を表し、Ｘ⁹は、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ₂−を表し、Ｘ¹⁰は、−ＮＨ−または−Ｏ−を表し、Ｙは、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または置換基を有してもよいアリーレン基を表し、Ｚは、−ＳＯ₃Ｍ、−ＣＯＯＭ、−Ｐ（Ｏ）（−ＯＭ）₂または−Ｏ−Ｐ（Ｏ）（−ＯＭ）₂を表し、Ｍは１〜３価のカチオンの一当量を表し、Ｒ⁹は、有機色素残基を表し、ｎは、１〜４の整数を表す。］ 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 1 to 3 valent 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 described above. 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 used in the present invention is not particularly limited. For example, JP-B-39-28884, JP-B-45-11026, JP-B-45-29755, They can be synthesized by the methods described in JP-A No. 64-5070, JP-A No. 2004-217842, 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 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 which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, which is composed of 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.
^R102 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.
General formula (102)

一般式（１０３）

General formula (103)

一般式（１０４）

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 represents 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.

o represents an integer of 1 to 4.
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, U represents -X ¹⁰⁹ -R ^111, or W ^2.
W ¹ and W ² each independently represent —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 represents an NHCOCH ₂ NH-.
R ¹¹⁰ and R ¹¹¹ each independently represents an organic dye residue, an optionally substituted heterocyclic residue or an optionally substituted aromatic ring residue.

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, for example, 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, pyrazole, 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は、下記一般式（１０７）、一般式（１０８）または一般式（１０９）で示される基である。ｍは、１〜４の整数を表す。
一般式（１０７）

一般式（１０８）

Z ¹⁰¹ 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)

一般式（１０９）

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, which is composed of 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, and 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, flavantron, 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, Octylamine, 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-dibutylaminobutyl Ruamine, N, N-diisobutylaminopentylamine, N, N-methyl-laurylaminopropylamine, N, N-ethyl-hexylaminoethylamine, N, N-distearylaminoethylamine, N, N-dioleoylaminoethylamine, 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-aminopropylpiperidi N-aminopropyl-2-pipecoline, N-aminopropyl-4-pipecoline, N-aminopropylmorpholine, N-methylpiperazine, N-butylpiperazine, N-methylhomopiperazine, 1-cyclopentylpiperazine, 1-amino Examples include -4-methylpiperazine and 1-cyclopentylpiperazine.

  The method for synthesizing the organic dye derivative having a basic functional group or the triazine derivative having a basic functional group according to the present invention is not particularly limited, but is described in JP-A No. 54-62227 and JP-A No. 56-. No. 118462, JP-A 56-166266, JP-A 60-88185, JP-A 63-305173, JP-A 3-2676, JP-A 11-199796, etc. It can be synthesized by the method.

For example, the organic dye derivative having a basic functional group of the present invention is represented by formula (110) to formula (113) as an organic dye, a heterocyclic compound (for example, acridone) or an aromatic ring compound (for example, anthraquinone). After introducing the substituent, these substituents and amine components (eg, 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.

Equation (110) -SO ₂ Cl
Formula (111) -COCl
Equation (112) -CH ₂ NHCOCH ₂ Cl
Equation (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 between the substituent represented by formula (110) to formula (113) and the amine component, a part of the substituent represented by formula (110) to formula (113) is hydrolyzed, and chlorine is substituted with a hydroxyl group. 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 coupled. 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 is a C 1-20 alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent. 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 formulas (102), (103), or (104) Represents a group.
^R102 represents a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or an aryl group which may have a substituent.

  The triazine derivative having a basic functional group of the present invention is represented by, for example, cyanuric chloride as a starting material, and at least one chlorine of cyanuric chloride represented by formula (107) to formula (109) or general formula (114). It is obtained by reacting an amine component (for example, N, N-dimethylaminopropylamine or N-methylpiperazine etc.) that forms a substituent, and then reacting the remaining chlorine of cyanuric chloride with various amines or alcohols. It is done.

  The pigment derivative used in the present invention 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 has an acidic or basic functional group. A triazine derivative is more preferred, a triazine derivative having an acidic functional group is further preferred, and a triazine derivative having no acidic functional group and having an acidic functional group is particularly preferred.

You may use the said pigment derivative, mixing 1 type (s) or 2 or more types in arbitrary ratios.
In the present invention, it is considered that the pigment derivative mainly functions as a dispersant and also plays a role for creating an electrode film state suitable for improving battery performance.

<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 of the polyvinyl alcohol and the pigment derivative as a dispersant and the battery performance are not impaired. However, from the industrial applicability assumed by the present invention. , NMP is preferably used alone.

<Method for producing carbon black dispersion>
The dispersion of the present invention is obtained by dispersing carbon black in NMP using polyvinyl alcohol and a pigment derivative as a dispersant. 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 dispersion device, a disperser usually used for pigment dispersion or the like can be used. For example, mixers such as dispersers, homomixers, planetary mixers, homogenizers (such as “Clairemix” manufactured by M Technique, “Fillmix” manufactured by PRIMIX, “Abramix” manufactured by Silverson, etc.), paint conditioners ( Red Devil), colloid mill ("PUC colloid mill" manufactured by PUC, "colloid mill MK" manufactured by IKA), cone mill ("Cone mill MKO" manufactured by IKA), 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, polyvinyl alcohol and a pigment derivative obtained by the following dry treatment in NMP.

  In the dry treatment in the present invention, the above-mentioned dispersant is allowed to act (adsorb) on the surface of carbon black while mixing, pulverizing, and the like of carbon black, polyvinyl alcohol and a pigment derivative with a dry treatment apparatus at room temperature or under heating. . However, it is not necessary that the dispersant is completely adsorbed on the carbon black surface, and if it can be mixed to some extent homogeneously, there may be no practical problem. 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.

  Moreover, you may add an organic solvent in the range by which a processed material does not become a gel form at this time. It is expected that the interaction between the carbon black and the dispersant is promoted by improving the wetting or (partial) dissolution of the polyvinyl alcohol and the pigment derivative by the addition of the solvent and the wetting of the carbon black with the dispersant. 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. Moreover, although the addition amount of an organic solvent changes with materials to be used, it is 0.5 to 100 weight% with respect to the addition amount of the said dispersing agent. 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 processing 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 present invention, the addition amount of polyvinyl alcohol and a pigment derivative as a dispersant for carbon black is preferably 50 parts by weight or less, and 0.5 parts by weight or more and 40 parts by weight with respect to 100 parts by weight of carbon black. Is 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, further preferably 1 part by weight or more and 10 parts by weight or less, and more preferably 1 part by weight or more. 8 parts by weight or less is particularly preferable.

  In the present invention, the amount of polyvinyl alcohol added as a dispersant to carbon black is preferably 0.1 parts by weight or more and 20 parts by weight or less, and 0.15 parts by weight or more and 10 parts by weight with respect to 100 parts by weight of carbon black. Is more preferably 0.2 parts by weight or more and 8 parts by weight or less, further preferably 0.2 parts by weight or more and 4 parts by weight or less, and particularly preferably 0.4 parts by weight or more and 4 parts by weight or less. .

  In the present invention, the ratio of polyvinyl alcohol in the dispersant is preferably 10 parts by weight or more and 90 parts by weight or less, more preferably 20 parts by weight or more and 80 parts by weight or less, and more preferably 25 parts by weight or more with respect to 100 parts by weight of the dispersant. 75 parts by weight or less is particularly preferable.

The addition amount of the dispersant in the carbon black dispersion is determined by the specific surface area of the carbon black to be added, the average particle diameter after dispersion of the carbon black particles, the adsorption amount of the dispersant on the carbon black, and the like.
By blending at the above ratio, it becomes possible to lower the viscosity of the carbon black dispersion, which is a problem to be solved by the present invention, and to obtain a dispersion having a high concentration and excellent dispersibility and storage stability. Becomes easy.

<Active material>
When using the dispersion liquid of this invention for a battery electrode compound-material layer, a positive electrode active material or a negative electrode active material can be contained further.

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, and transition metal sulfide powders such as TiS ₂ and FeS. 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, 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 polymers 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.

<Electrode>
By coating and drying the carbon black dispersion containing the positive electrode active material or the negative electrode active material of the present invention 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.

  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.

  Moreover, you may perform the rolling process by a lithographic press, a calender roll, etc. after application | coating. The thickness of the 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 the above electrode for at least one of a positive electrode and a 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 electrolytes, 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)
The structure of the lithium ion secondary battery using the composition of the present invention is not particularly limited, but is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary, a paper type, a cylindrical type, a button type, It can be made into various shapes according to the purpose of use, such as a laminated type.

In the present invention, 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 above-described problems are not affected.
Examples of such a dispersant include a polyvinyl acetal resin, a polyvinyl pyrrolidone resin, 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 of the present invention is not particularly limited, but is a field where light shielding properties, electrical conductivity, durability, jetness, etc. are required, for example, gravure ink, offset ink, magnetic recording medium back In coatings, electrostatic toners, ink jets, automobile paints, fiber / plastic forming materials, battery electrodes, and electrophotographic seamless belts, a stable and uniform composition can be provided. 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 the carbon black dispersion of the present invention and further adding a binder such as polyvinylidene fluoride and polytetrafluoroethylene, a primer for a lithium ion secondary battery electrode, an electric double layer capacitor electrode, or a lithium ion capacitor electrode Lithium ion secondary battery by adding a layer, and 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 Electrode layers for electrodes, electrodes for electric double layer capacitors, and electrodes for lithium ion capacitors can be manufactured. In addition, the electrophotographic seamless belt can be produced by a conventionally known method using the carbon black dispersion of the present invention as a conductive material, polyimide, polyamideimide, and the like as precursors.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, 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. Moreover, although only the composition of each raw material is described in each table, the remaining components not particularly described are all N-methyl-2-pyrrolidone (NMP).

<Carbon black>
# 30 (Mitsubishi Chemical Co., Ltd.): Furnace black, average primary particle size 30 nm, specific surface area 74 m ² / g, hereinafter abbreviated as # 30.
# 5 (Mitsubishi Chemical Co., Ltd.): Furnace black, average primary particle diameter 76 nm, specific surface area 29 m ² / g, hereinafter abbreviated as # 5.
MA77 (Mitsubishi Chemical Corporation): oxidized carbon black, average primary particle size 23 nm, specific surface area 130 m ² / g, hereinafter 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 abbreviated as HS-100.
Denka black granular product (manufactured by Denki Kagaku Kogyo Co., Ltd.): Acetylene black, average primary particle size 35 nm, specific surface area 69 m ² / g, hereinafter abbreviated as granular product.
EC-300J (manufactured by Akzo): Ketjen black, average primary particle size 40 nm, specific surface area 800 m ² / g, hereinafter abbreviated as 300 J.

(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 the mixture in a water bath of an ultrasonic cleaner for 1 minute. This sample was applied to a measurement target, dried, and taken with a transmission electron microscope (transmission electron microscope H-7650, manufactured by Hitachi High-Technologies Corporation) to photograph 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 (201).

Formula (201) MV = Σ (V · d) / Σ (V)

<Resin containing general formula (A)>
<Polyvinyl alcohol>
Kuraray poval PVA-505 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 73 mol%, average polymerization degree 500, hereinafter abbreviated as PVA-505.
Kuraray poval PVA-105 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 98 mol%, average polymerization degree 500, hereinafter abbreviated as PVA-105.
Kuraray Poval LM-20 (manufactured by Kuraray Co., Ltd.): polyvinyl alcohol, saponification degree 40 mol%, average polymerization degree 200, hereinafter 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.
The synthetic products 1 to 7 are 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, 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 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 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>
Table 1 shows the structure of an organic dye derivative having an acidic functional group.

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

<Basic pigment derivative>
Table 3 shows the structure of an organic dye derivative having a basic functional group.

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

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

<Other compounds>
1,2,3,4-benzenetetracarboxylic acid, hereinafter 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 abbreviated as graphite.

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

  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 60 ° C. for 10 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 performed 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 above 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 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 5, NMP, various polyvinyl alcohols, and various pigment derivatives were charged into a glass bottle, mixed and dissolved or dispersed sufficiently, and then carbon black was added. Each carbon black dispersion was obtained by dispersing for 2 hours. 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 6, NMP, various polyvinyl alcohols, various pigment derivatives, and PVDF are charged into a glass bottle, mixed and dissolved or mixed and dispersed, and then carbon black is added and dispersed for 1 hour with a homogenizer. A liquid 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 6, NMP, polyvinyl alcohol, and a pigment derivative were charged into a glass bottle, and sufficiently 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 6, 65 parts of the carbon black dispersion of Example 1-2, 6 parts of PVDF or 3 parts of # 7300, 29 parts or 32 parts of NMP were added to a glass bottle, and dispersed for 1 hour with a homogenizer. 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 6, NMP, polyvinyl alcohol, pigment derivative and # 7300 were charged into a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, added with carbon black, and dispersed with a homogenizer for 1 hour. Got. 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 6, NMP, various polyvinyl alcohols or various polyvinyl acetal resins, various pigment derivatives and PVDF were charged into a glass bottle, and sufficiently mixed and dissolved or mixed and dispersed. Then, carbon black was added and the homogenizer was used for 1 hour. Each carbon black dispersion was obtained by dispersing.
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.
Furthermore, in Comparative Example 2-1 to Comparative Example 2-2 and Comparative Example 2-6 to Comparative Example 2-7, both are extremely high viscosity 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 6, 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 high as when the dispersion was prepared without adding the binder of Table 5. It can be seen that a dispersion having a low 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 6, NMP, polyvinyl alcohol, pigment derivative and PVDF are charged into a glass bottle, and after thoroughly mixing, dissolving or mixing, various carbon blacks are added and dispersed for 1 hour with a homogenizer. Got. 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 7, NMP, polyvinyl alcohol, various pigment derivatives and PVDF were charged into a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, then carbon black was added and dispersed with a homogenizer for 1 hour. Got. 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 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. In addition, each carbon black dispersion was obtained by dispersing with a homogenizer for 1 hour. The obtained liquid was in a remarkably high viscosity state and had a large D50 value, so it was found 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 8, NMP, polyvinyl alcohol, various pigment derivatives and PVDF were charged into a glass bottle, mixed and dissolved or mixed and dispersed sufficiently, added with carbon black, and dispersed with a homogenizer for 1 hour. Got. 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 8, NMP, polyvinyl alcohol, pigment derivative and PVDF are charged into a glass bottle and mixed and dissolved or mixed and dispersed. Carbon black is added and dispersed with a homogenizer for 1 hour. Obtained. The obtained liquid was in a remarkably high viscosity state and had a large D50 value, so it was found 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 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 Example The carbon black dispersion containing the binder obtained in Example 3-17, Example 4-1 to Example 4-7, and Example 4-9 was charged with LCO, which is a positive electrode active material, and sufficiently dispersed with a disper. Each mixture was obtained by mixing. 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 9, 2.7 parts of HS-100, 1.25 parts of PVDF, 0.011 part of polyvinyl alcohol, 0.043 parts of pigment derivative, and 63 parts of LCO, homogeneously mixed powder After preparing the body mixture, half of the total amount of the powder mixture was added to 32.996 parts of NMP, and the mixture was treated 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 resulting liquid was in a low viscosity state as in Example 5-23.

[Example 5-25 to Example 5-28]
In accordance with the composition shown in Table 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. A 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 9, the carbon black dispersion containing the binder obtained in Comparative Example 2-3, Comparative Example 2-5, Comparative Example 2-8, Comparative Example 2-10, and Comparative Example 4-1. On the other hand, LCO, which is a positive electrode active material, was charged and thoroughly 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 LCO is added is larger than that in Example 5-1 to Example 5-23, and the stability is high. The increase in viscosity in the evaluation test was also large.

[Comparative Example 5-6 to Comparative Example 5-8]
In accordance with the composition shown in Table 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, and 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 Example 5-25 to Example 5-28, and the stability is high. 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 according to JIS K7194 using Loresta GP (manufactured by Mitsubishi Chemical Analytech).
The smaller the numerical value, the better the surface resistance. When measurement was not possible, no value was given (-). Further, the appearance of the coating film was visually determined as follows: ○: no problem (good), Δ: spotted pattern (possible), ×: coarse grain streaking (very bad).

[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 Example 5-4 to Comparative Example 5-5, a positive electrode mixture layer (battery electrode mixture layer) was produced. The evaluation results are shown in Table 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 10.
From Table 10, the battery electrode mixture layers of Example 6-1 to Example 6-24 have a better coating film appearance than the battery electrode mixture layers of Comparative Examples 6-1 to 6-5. Furthermore, it was revealed that the surface resistance of the coating film was excellent. In Comparative Example 6-1 to Comparative Example 6-5, coating is difficult because the viscosity of the electrode mixture liquid used is too high. Further, in Comparative Examples 6-3 and 6-5, a large amount 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 liquid of Comparative Example 5-4 to Comparative Example 5-5) were applied on a 20 μm thick aluminum foil serving as a current collector using a doctor blade, and then heated at 120 ° C. under reduced pressure. After drying, it was rolled with a roller press to produce a positive electrode mixture layer having a thickness of 100 μm. 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 is dissolved at a concentration of 1M in a mixed solvent of ethylene carbonate and diethyl carbonate mixed at a volume ratio of 1: 1) is 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>
[Example 7-22 to Example 7-24, Comparative Example 7-4 to Comparative Example 7-5]
The previously prepared battery electrode mixture liquid (the 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) was collected. After coating with a doctor blade on a copper foil having a thickness of 20 μm, which was to be a body, it was dried by heating at 120 ° C. under reduced pressure, and then rolled with a roller press to produce a negative electrode mixture layer having a thickness of 100 μm. . 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 is dissolved at a concentration of 1M in a mixed solvent of ethylene carbonate and diethyl carbonate mixed at a volume ratio of 1: 1) is 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>
Using the charging / discharging device (SM-8 manufactured by Hokuto Denko Co., Ltd.) at 40 ° C., the prepared positive electrode evaluation cell was fully charged with constant current and constant voltage charging (upper limit voltage 4.2 V) at a charging rate of 1.0 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. The case where the composite material was partially peeled off from the current collector was defined as x (defect). 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. When a normal charge / discharge curve could not be obtained due to peeling of the coating film from the current collector, short-circuiting, or the like, and the capacity could not be obtained, it was set to no numerical value (-). The evaluation results are shown in Table 11.

<Evaluation of lithium ion secondary battery negative electrode characteristics>
Using the charging / discharging device (SM-8 manufactured by Hokuto Denko Co., Ltd.) at 40 ° C., the prepared negative electrode evaluation cell was fully charged with constant current and constant voltage charging (lower limit voltage 0.5 V) at a charging rate of 1.0 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 11.

  From Table 11, Example 7-1 to Example 7-21 and Example 7-22 to Example 7-24 using the electrode of the present invention are Comparative Example 7-1 to Comparative Example 7-3 and Comparative Example. As compared with 7-4 to Comparative Example 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 11, it was found that Example 7-1 to Example 7-24 had a good coating film appearance and a good capacity retention rate even after 50 charge / discharge cycles. On the other hand, Comparative Example 7-1 to Comparative Example 7-5 could not obtain a good coating film, and therefore could not evaluate the positive electrode characteristics and the negative electrode characteristics.

Claims (9)

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 carbon black 100 The total amount of polyvinyl alcohol and triazine derivative, or polyvinyl alcohol and organic pigment derivative as the dispersant relative to parts by weight is 50 parts by weight or less, and the polyvinyl alcohol is represented by the following general formula (A) A carbon black dispersion comprising 50 to 95 mol% of repeating units in a polymer chain.

Formula (A)

  The carbon black dispersion according to claim 1, wherein the dispersant is the polyvinyl alcohol and a triazine derivative.   The carbon black dispersion according to claim 1 or 2, wherein the polyvinyl alcohol contains 55 to 85 mol% of a repeating unit represented by the general formula (A) in a polymer chain. The total amount of polyvinyl alcohol and triazine derivative, or the total amount of polyvinyl alcohol and organic pigment derivative is 0.5 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of carbon black. The carbon black dispersion according to claim 1 or 3 .
  The carbon black dispersion according to any one of claims 1 to 4, wherein polyvinyl alcohol is 0.2 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of carbon black.   The carbon black dispersion according to any one of claims 1 to 5, wherein the polyvinyl alcohol is 0.2 to 8 parts by weight with respect to 100 parts by weight of the carbon black.   A carbon black dispersion for a battery, wherein the carbon black dispersion according to claim 1 further contains a positive electrode active material or a negative electrode active material.   A battery electrode mixture layer formed by applying the carbon black dispersion according to claim 1 or the battery carbon black dispersion according to claim 7.   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 One is a lithium ion secondary battery comprising the battery electrode mixture layer according to claim 8.