JP2021190330A - Conductive material dispersion and method for manufacturing the same - Google Patents

Abstract

To provide: a conductive material dispersion excellent in compatibility with a binder and storage stability, and a conductive paint and a composition for a secondary battery electrode, in which the conductive material dispersion is used; an electrode membrane capable of improving output and cycle life; and a secondary battery excellent in output and cycle life.SOLUTION: There is provided a conductive material dispersion including a conductive material, a copolymer (A), a base (B) and water. The conductive material dispersion includes, as the conductive material, single layer carbon nanotubes with an average outer diameter of 1-4 nm. The copolymer (A) is a copolymer containing 10-99 mass% of unit derived from methacrylonitrile and 1-50 mass% of carboxyl group-containing monomer unit, with respect to 100 mass% of the total of all units. The base (B) has a pKb at 25°C in water of 5 or less, and a solubility at 25°C in water of 1 g/100 ml or more. The solid content mass ratio (B)/(A) of the copolymer (A) and the base (B) is 0.2-1.0.SELECTED DRAWING: None

Description

The present invention comprises forming a conductive material dispersion containing carbon nanotubes having excellent compatibility with a paint binder and storage stability, a conductive paint containing a conductive material dispersion and a binder resin, and forming a film thereof. A conductive coating film, a mixture slurry containing a conductive dispersion, a binder resin, and an active material, an electrode film formed in the form of a film, and a non-aqueous electrolyte provided with an electrode film and an electrolyte. Regarding the conductive material dispersion for the next battery.

In recent years, materials having functions such as antistatic property, conductivity, thermal conductivity, and electromagnetic wave shielding property have been actively developed using materials containing carbon nanotubes. For example, a polymer such as polyamide, polyester, polyether or polyimide, or an inorganic material such as glass or ceramics material is used as a matrix, and carbon nanotubes are dispersed in these matrices to prevent static electricity, conductivity, and heat. Many studies have been conducted on composite materials having functions such as conductivity and electromagnetic wave shielding properties, and laminates obtained by laminating these composite materials.

For example, non-aqueous electrolyte secondary batteries, particularly lithium ion secondary batteries, are attracting attention as applications using carbon nanotube dispersions. By adding carbon nanotubes to graphite or silicon negative electrode as the negative electrode material, the electrode resistance can be reduced, the load resistance of the battery can be improved, the strength of the electrode can be increased, and the expansion and contraction property of the electrode can be increased. It improves the cycle life of the ion secondary battery. (See, for example, Patent Documents 1, 2 and 3) Further, studies have been made to reduce the electrode resistance by adding carbon nanotubes to the positive electrode. (See, for example, Patent Documents 4 and 5).

When a conductive material having a large specific surface area is used, a conductive network can be efficiently formed with a small amount, and the amount of the conductive material contained in the positive electrode and the negative electrode for a lithium ion secondary battery can be reduced. However, since a conductive material having a large specific surface area has a strong cohesive force and is difficult to disperse, it has not been possible to obtain a conductive material dispersion having sufficient dispersibility.

Therefore, a method of dispersing and stabilizing the conductive material by using various dispersants has been proposed. For example, dispersion in water and NMP (N-methyl-2-pyrrolidone) using a polymer-based dispersant such as a water-soluble polymer polyvinylpyrrolidone has been proposed (see Patent Documents 4 and 5).

However, since PVA and PVP are generally highly hydrophilic and have the property of being soluble in water, when used as a dispersant for carbon black, the water resistance of the coating film is lowered when the dispersion is used as a coating film. Problems such as occur. For example, when a carbon dispersion using PVA or PVP is used as the dispersion for a lithium-ion battery, problems such as deterioration of battery performance due to moisture absorption occur.

Further, examples of applications using carbon nanotube dispersions include transparent antistatic paints. In order to utilize the characteristics of carbon nanotubes by coating, it is necessary to form a network structure of carbon nanotubes dispersed on the substrate. This is expected to enable high transparency and conductivity to be exhibited even when the amount of carbon nanotubes used is extremely small.

Until now, a method of producing a conductive film by applying a conductive layer using carbon nanotubes onto the film has been known. However, in these known techniques, for example, Patent Document 6, since the coating film thickness becomes extremely thick in order to impart desired conductivity, transparency is ignored as a conductive substrate. Further, in Patent Document 7, in order to maintain the conductivity of the carbon nanotubes in the conductive layer, the conductive polymer of the conjugated polymerization system is used as the binder resin, but the conductive properties originally possessed by the carbon nanotubes are utilized. As a conductive film, the resistance value is extremely high. In Patent Document 8, since the conductive characteristics of carbon nanotubes are exhibited, the manufacturing process of the conductive film becomes complicated, and there is a problem in productivity and economy. In Patent Document 9, carbon nanotubes are applied to improve the adhesiveness between the conductive layer and the base material, and then a binder resin is overcoated on the carbon nanotubes, which causes problems in productivity and economy as in Patent Document 8. be. Further, since the four patent documents shown here use an organic solvent as a solvent, it cannot be said to be optimal in terms of environmental load.

Japanese Unexamined Patent Publication No. 4-155776 Japanese Unexamined Patent Publication No. 4-237971 Japanese Unexamined Patent Publication No. 2004-178922 Japanese Unexamined Patent Publication No. 2011-070908 Japanese Unexamined Patent Publication No. 2014-19619 Japanese Unexamined Patent Publication No. 2002-67209 Japanese Unexamined Patent Publication No. 2004-195678 Japanese Unexamined Patent Publication No. 2007-11123 Japanese Patent No. 366969

Even in the conventional technology so far, in order to produce a film in which carbon nanotubes are dispersed, carbon nanotubes are dispersed in a matrix or a resin. However, the dispersed state of the carbon nanotubes is not always good, and in the conventional lamination by coating, the binder resin inhibits the conductivity of the carbon nanotubes, and the carbon nanotubes agglomerate in the coating process and the drying process. It was difficult to express the original characteristics of.

An object of the present invention is to improve such drawbacks of the prior art and to provide a conductive material dispersion in which carbon nanotubes having excellent compatibility with a binder and storage stability are dispersed. Another object of the present invention is to provide a conductive coating material having both good conductivity and transparency, and a composition for a secondary battery electrode having good conductivity. Further, an object of the present invention is to provide an electrode film capable of improving the output and cycle life of a secondary battery, and a secondary battery having high output and good cycle life.

As a result of diligent studies to achieve the above object, the present inventors have made carbon nanotubes having a specific diameter as a conductive material, a copolymer having a specific structural unit as a dispersant, specific pKb and water. It has been found that a conductive material dispersion having good storage stability and compatibility can be produced by combining the types of bases having solubility in and the ratio thereof. Further, a conductive coating material having both good conductivity and transparency, a composition for a secondary battery electrode having good conductivity, an electrode film capable of improving the output and cycle life of a secondary battery, and high output and good quality. It has been found to manufacture a secondary battery having a long cycle life.

That is, the present invention includes the following embodiments. The embodiments of the present invention are not limited to the following.

The present invention is a conductive material dispersion containing a conductive material, a copolymer (A), a base (B), and water.
The conductive material contains single-walled carbon nanotubes having an average outer diameter of 1 to 4 nm.
The copolymer (A) contains 10% by mass to 99% by mass of units derived from (meth) acrylonitrile and 1% by mass to 50% by mass of carboxyl group-containing monomer units, based on a total of 100% by mass of all units. It is a copolymer, and the base (B) has a pKb of 5 or less at 25 ° C. in water and a solubility of 1 g / 100 ml or more at 25 ° C. in water, and the copolymer (A) and the base (B). ) Shall have a solid content mass ratio (B) / (A) of 0.2 to 1.0.

The present invention also relates to the conductive material dispersion containing 11 to 40% by mass of a carboxyl group-containing monomer unit with respect to 100% by mass of the copolymer (A).

The present invention also relates to the conductive material dispersion, which is characterized in that the pKb of the base (B) is 1 or less.

The present invention also relates to the conductive material dispersion, wherein the copolymer (A) contains acrylic acid and itaconic acid as a carboxyl group-containing monomer unit.

The present invention also relates to the conductive material dispersion, which is characterized by containing an acid.

The present invention also relates to the conductive material dispersion, which comprises a total of 20% by mass to 1000% by mass of the copolymer (A) and the base (B) with respect to the conductive material.

The present invention also relates to the conductive material dispersion, which is characterized in that the 50% particle size (D50) calculated by the laser diffraction type particle size distribution measurement is 1.5 to 40 μm.

The present invention also relates to the conductive material dispersion, which is characterized in that the pH is 8.0 to 13.0.

The present invention also relates to the conductive material dispersion, which is characterized in that the specific surface area of the conductive material is 400 to 800 m ^{2 / g.}

The present invention also relates to a composition for a secondary battery electrode, which comprises the conductive material dispersion.

The present invention also relates to an electrode film which is a coating film of the composition for a secondary battery electrode.

The present invention also relates to a secondary battery including the electrode film.

The present invention also relates to a conductive coating material containing the conductive material dispersion.

The present invention also relates to a conductive coating film, which is a coating film for the conductive coating material.

Further, the present invention is a method for producing a conductive dispersion containing a conductive material, a copolymer (A), a base (B), and water.
The conductive material contains single-walled carbon nanotubes having an average outer diameter of 1 to 4 nm.
The copolymer (A) is a copolymer containing a unit derived from (meth) acrylonitrile and a carboxyl group-containing monomer unit, and the base (B) has a pKb of 5 or less at 25 ° C. in water and is 5 or less. A step of dispersing the conductive material, the copolymer (A), the base (B), and water at a pH of 9.0 to 13.5, wherein the solubility in water at 25 ° C. is 1 g / 100 ml or more. The present invention relates to a method for producing a conductive dispersion, which comprises a step of neutralizing the obtained dispersion.

According to the embodiment of the present invention, it is possible to provide a conductive material dispersion in which carbon nanotubes having excellent compatibility with a binder and storage stability are dispersed. Further, according to the embodiment of the present invention, it is possible to provide a conductive coating material having both good conductivity and transparency, and a composition for a secondary battery electrode having good conductivity. Further, according to the embodiment of the present invention, it is possible to provide an electrode film capable of improving the output and cycle life of the secondary battery, and a secondary battery having high output and good cycle life.

<Conductive material>
The conductive material of this embodiment is a single-walled carbon nanotube. The single-walled carbon nanotube has a shape in which flat graphite is wound in a cylindrical shape, and has a structure in which one layer of graphite is wound.

The average outer diameter of the carbon nanotubes is 1 to 4 nm, preferably 1 to 2 nm. The average outer diameter of carbon nanotubes is determined by observing the morphology of carbon nanotubes with a transmission electron microscope (manufactured by JEOL Ltd.), measuring the lengths of 100 short axes, and using the average value of the numbers as the average outer diameter of carbon nanotubes. It was set to (nm).

The specific surface area of the carbon nanotubes is preferably 400~1200m ² / g, more preferably 400 to 800 m ² / g. When the specific surface area is 400 m ² / g or more, a network of carbon nanotubes is easily formed in the coating film and the conductivity is improved, and when the specific surface area is 800 m ² / g or less, the carbon nanotubes are easily unraveled in the dispersion step. , Since the structural destruction of carbon nanotubes does not easily proceed, the conductivity is improved.

The carbon component of the carbon nanotubes is preferably 70 to 90%, more preferably 80 to 90%. The carbon nanotube (A) may contain a catalyst component, and the value obtained by subtracting the catalyst component from the carbon nanotube is referred to as a carbon component. The value of the carbon component was calculated according to the formula (1) by measuring the ash content after firing in the presence of 900 ° C. in the air for 5 hours.
Carbon component of carbon nanotube (%) =
1- (weight of ash after firing (g) / weight of carbon nanotubes before firing (g)) x 100
・ ・ ・ ・ Equation (1)
When the carbon component is in the range of 70 to 90%, a good dispersion can be obtained. Known techniques include improving the yield in the process of producing carbon nanotubes and removing the catalyst component by acid purification of the obtained carbon nanotubes as means for increasing the carbon component, but this is not preferable because the conductivity is lowered.

The 50% particle size (D50) calculated by the laser diffraction type particle size distribution measurement of the carbon nanotubes is preferably 500 to 1300 μm, more preferably 800 to 1200 μm.

Examples of such carbon nanotubes (A) include ZEONANO SG101 (outer diameter: 3 to 5 nm) manufactured by Zeon Corporation, TUBALL (outer diameter: 1 to 2 nm) manufactured by OCSiAl, and the like, as single-walled carbon nanotubes. However, it is not limited to these.

The dispersion of the present embodiment contains a copolymer (A) containing a unit derived from (meth) acrylonitrile and a carboxyl group-containing monomer unit, and has a pKb of 5 or less at 25 ° C. in water and 25 ° C. in water. Contains the base (B) having a solubility in 1 g / 100 ml or more.

The copolymer (A) and the base (B) are not particularly limited, but function as a dispersant for dispersing the conductive material, and may be used after being dissolved or semi-dissolved in water in advance, and may be dispersed. Sometimes it may be used while being dissolved or semi-dissolved.

<Copolymer (A)>
Examples of the monomer unit derived from (meth) acrylonitrile include acrylonitrile and meta-acrylonitrile. One type can be used alone or in combination of two or more types, and acrylonitrile is preferable. When the monomer unit derived from (meth) acrylonitrile is acrylonitrile, the bending of the copolymer is reduced, and the adjacent cyano groups are oriented to form a partially structured structure with strong polarization. Alternatively, the intermolecular force between the dispersant and water increases. The content of the monomer unit derived from (meth) acrylonitrile is 10% by mass to 99% by mass, and from the viewpoint of increasing the intermolecular force, 52% by mass is based on the mass of all the monomer units constituting the copolymer. The above is preferable, 60% by mass or more is preferable, and 70% by mass or more is more preferable. Based on the mass of all the monomer units constituting the copolymer, it is preferably 89% by mass or less, and more preferably 85% by mass or less. By setting the content of the monomer unit derived from (meth) acrylonitrile in the above range, the dispersion can be stably present in the dispersion medium. Further, when used in a secondary battery, it is possible to prevent problems such as the dispersant dissolving in the electrolytic solution in the battery and increasing the resistance of the electrolytic solution.

The carboxyl group-containing monomer unit is, for example, unsaturated fatty acids such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid, 2- (meth) acryloyloxyethyl phthalate, and 2- (meth). Carboxyls such as acryloyloxypropylphthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, 2- (meth) acryloyloxypropylhexahydrophthalate, ethylene oxide-modified succinic acid (meth) acrylate, β-carboxyethyl (meth) acrylate Group-containing (meth) acrylate and the like can be mentioned. In addition, acid anhydride group-containing monomers such as maleic anhydride, itaconic anhydride, and citraconic anhydride, which are multimers of the above carboxyl group-containing monomers, and monofunctional alcohol adducts thereof and the like can be mentioned. "-C (= O) -OC (= O)-" (referred to as "acid anhydride group" in the present specification), which is a group having a structure in which two carboxyl groups are dehydrated and condensed, is also a carboxyl group by hydrolysis. In the present specification, it is included in the carboxyl group in order to form. As the carboxyl group-containing monomer, unsaturated fatty acids are preferable, (meth) acrylic acid is more preferable, and acrylic acid is even more preferable. Further, it is more preferable to contain both acrylic acid and itaconic acid. The content of the carboxyl group-containing monomer unit is 1% by mass to 50% by mass, and from the viewpoint of having an appropriate affinity with water as a dispersion medium, the mass of all the monomer units constituting the copolymer is used as a reference. It is preferably 11% by mass or more, and more preferably 15% by mass or more. Based on the mass of all the monomer units constituting the copolymer, it is preferably 48% by mass or less, preferably 40% by mass or less, and more preferably 30% by mass or less.

The copolymer (A) may contain one or more monomer units selected from the group consisting of an active hydrogen group-containing monomer (excluding a carboxyl group), a basic monomer, and a (meth) acrylic acid alkyl ester. By selecting and containing the above-mentioned monomer according to the characteristics such as hydrophilicity, hydrophobicity, acidity, and basicity of the base material to which the conductive material dispersion of the present invention is applied and the material to be mixed, it can be applied to various uses. be able to. The content of one or more monomer units selected from the group consisting of active hydrogen group-containing monomers (excluding carboxyl groups), basic monomers, and (meth) acrylic acid alkyl esters is the content of all the monomers constituting the copolymer. Based on the mass of the unit, 20% by mass or less is preferable, 10% by mass or less is more preferable, and 5% by mass or less is further preferable.
When it is included in the above range, it is possible to impart appropriateness to various uses while maintaining a high intramolecular force.
Of one or more monomer units selected from the group consisting of an active hydrogen group-containing monomer (excluding a carboxyl group), a basic monomer, and a (meth) acrylic acid alkyl ester used for the synthesis of the copolymer (A). The active hydrogen group-containing monomer is a monomer having, for example, a hydroxyl group, a primary amino group, a secondary amino group, a mercapto group, or the like as an active hydrogen group. Here, the "primary amino group" _{means -NH 2} (amino group), and the "secondary amino group" means that one hydrogen atom on the primary amino group is replaced with an organic residue such as an alkyl group. Means the group that was made. However, the primary amino group and the secondary amino group in the acid amide are not included in the active hydrogen group in the present specification.

The hydroxyl group-containing monomer is, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, 4-hydroxyvinylbenzene, 2-hydroxy. Examples thereof include -3-phenoxypropyl acrylate or a caprolactone adduct of these monomers (the number of moles added is 1 to 5). Among the active hydrogen group-containing monomers, a hydroxyl group-containing monomer is preferable from the viewpoints of easy availability of raw materials, ease of handling, affinity with a dispersion medium described later, and the like. The hydroxyl group-containing monomer is preferably hydroxyalkyl (meth) acrylate, more preferably hydroxyethyl (meth) acrylate, and even more preferably hydroxyethyl acrylate.

The primary amino group-containing monomer is, for example, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, allylamine hydrochloride, allylamine dihydrogen phosphate, 2-isopropenylaniline, 3-vinylaniline, 4-vinylaniline. And so on.

Examples of the secondary amino group-containing monomer include t-butylaminoethyl (meth) acrylate and the like.

Examples of the mercapto group-containing monomer include 2- (mercaptoacetoxy) ethyl acrylate, allyl mercaptan and the like.

The active hydrogen group-containing monomer can be used alone or in combination of two or more.

The basic monomer is a monomer having a basic group. Examples of the basic group include a tertiary amino group, an amide group, a pyridine ring, a maleimide group and the like. Although the monomer having a primary amino group and the monomer having a secondary amino group may be included in the basic monomer, they are treated as the active hydrogen group-containing monomer in the present invention and are not included in the basic monomer. ..

The basic monomer is, for example, dialkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylate;
N-substituted (meth) acrylamides such as (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and acryloyl morpholine;
Heterocyclic aromatic amine-containing vinyl monomers such as 1-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole;
N- (alkylaminoalkyl) (meth) acrylamides such as N- (dimethylaminoethyl) (meth) acrylamide and N- (dimethylaminopropyl) acrylamide;
Examples thereof include N, N-alkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide.

The basic monomer can be used alone or in combination of two or more. Among the basic monomers, dimethylaminoethyl (meth) acrylate or dimethylaminopropyl (meth) acrylate is preferable, and dimethylaminoethyl is preferable from the viewpoint of easy availability of raw materials, ease of handling, and compatibility with the dispersion medium described later. Acrylate is more preferred.

The (meth) acrylic acid alkyl ester has a structure represented by ^{(R 1} ) ₂ C = C-CO-O-R ^{2 (where R 1} is a hydrogen atom or a methyl group and at least one of them is a hydrogen atom. , R ² is an alkyl group which may have a substituent).
Those containing the active hydrogen group or the basic group as the substituent of the alkyl group are treated as the active hydrogen group-containing monomer or the basic monomer and are not included in the (meth) acrylic acid alkyl ester.
Examples of the (meth) acrylic acid alkyl ester include a chain alkyl group-containing (meth) acrylic acid ester such as methyl (meth) acrylate and ethyl (meth) acrylate;
Branched alkyl group-containing (meth) acrylic acid esters such as 2-ethylhexyl (meth) acrylate and isostearyl (meth) acrylate;
Cyclic alkyl group-containing (meth) acrylic acid ester such as (meth) cyclohexyl acrylate, (meth) isobornyl acrylate;
Aromatic ring-substituted alkyl group-containing (meth) acrylic acid alkyl esters such as (meth) benzyl acrylate and (meth) phenoxyethyl acrylate;
(Meta) acrylic acid alkyl esters substituted with fluorogroups such as trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate;
Epoxy group-containing (meth) acrylic acid alkyl esters such as (meth) glycidyl acrylate and (meth) acrylic acid (3-ethyloxetane-3-yl) methyl;
3-silyl ether group-containing (meth) acrylic acid alkyl esters such as methacryloxypropylmethyldimethoxysilane;
Alkyloxy group-containing (meth) acrylic acid alkyl esters such as 2-methoxyethyl (meth) acrylic acid and polyethylene glycol monomethyl ether (meth) acrylic acid;
Examples thereof include cyclizationally polymerizable monomers such as 2- (allyloxymethyl) methyl acrylate.

The (meth) acrylic acid alkyl ester can be used alone or in combination of two or more.
Among the (meth) acrylic acid alkyl esters, ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic from the viewpoint of availability of raw materials, ease of handling, and compatibility with the dispersion medium described later. 2-Ethylhexyl acrylate and lauryl (meth) acrylate are preferable, and 2-ethylhexyl acrylate and lauryl acrylate are more preferable.

The copolymer (A) of the present invention may further have another monomer unit. The monomers constituting the other monomer unit are, for example, styrene and styrenes such as α-methylstyrene;
Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, and isobutyl vinyl ether;
Vinyl acetate and fatty acid vinyls such as vinyl propionate;
N-substituted maleimides such as N-phenylmaleimide, N-cyclohexylmaleimide, etc .;
Examples thereof include heterocyclic (meth) acrylates such as tetrahydroflufreel (meth) acrylate or 3-methyloxetanyl (meth) acrylate; and the like.

The method for producing the copolymer (A) is not particularly limited, and examples thereof include a solution polymerization method, a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method, a precipitation polymerization method, and the like, and a solution polymerization method or a precipitation polymerization method. Is preferable. Examples of the polymerization reaction system include addition polymerization such as ion polymerization, free radical polymerization, and living radical polymerization, and free radical polymerization or living radical polymerization is preferable. Further, examples of the radical polymerization initiator include peroxides, azo-based initiators and the like. A molecular weight modifier such as a chain transfer agent can be used in the polymerization of the dispersant.

Chain transfer agents include, for example, alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, 3-mercapto-1,2-propanediol, octyl thioglycolate, nonyl thioglycolate, thioglycolic acid-2. Examples thereof include thioglycolic acid esters such as-ethylhexyl, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene and the like. In particular, 3-mercapto-1,2-propanediol, thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-Pinene and the like are preferable because the obtained polymer has a low odor.

The amount of the chain transfer agent used is preferably 0.01 to 4% by mass, more preferably 0.1 to 2% by mass, based on 100 parts by mass of all the monomer units. By setting the chain transfer agent in the above range, the molecular weight of the dispersant of the present invention can be adjusted to a suitable molecular weight range.

The weight average molecular weight of the dispersant is a polystyrene-equivalent weight average molecular weight, preferably 5,000 or more, more preferably 6,000 or more, and even more preferably 7,000 or more. Further, 400,000 or less is preferable, 200,000 or less is more preferable, 100,000 or less is further preferable, and 60,000 or less is particularly preferable. Having an appropriate weight average molecular weight improves the adsorptivity to the dispersion, and further improves the stability of the dispersion.

The acid value of the copolymer (A) can be determined by neutralization titration of KOH. The acid value of the copolymer (A) is preferably 30 mgKOH / g or more, more preferably 55 mgKOH / g or more, still more preferably 70 mgKOH / g or more. Further, 400 mgKOH / g or less is preferable, 300 mgKOH / g or less is more preferable, and 200 mgKOH / g or less is further preferable. By setting the acid value of the copolymer (A) in the above range, the affinity between the copolymer (A) and the dispersion medium can be appropriately controlled, and the affinity with the dispersion medium can be effectively controlled while being good. It will be possible to maintain a stable state of dispersion. When the acid value of the copolymer (A) exceeds the above range, the affinity for the dispersion medium becomes too high (that is, the solubility in water becomes too high), and when it falls below the above range, the affinity for the dispersion medium becomes too high. It may be too low (ie, too low in solubility in water), and in either case the action as the copolymer (A) may be low. Further, by setting both the amount of acidic groups of the conductive material and the acid value of the copolymer (A) within the above ranges, the affinity balance between the copolymer (A), the dispersion medium and the object to be dispersed is balanced. Is further improved, and the dispersibility is improved.

<Base (B)>
The conductive material dispersion of the present embodiment contains a base (B) having a pKb of 5 or less at 25 ° C. in water and a solubility of 1 g / 100 ml or more at 25 ° C. in water. The pKb is preferably 2 or less, more preferably 1 or less. The solubility is preferably 10 g / 100 ml or more, more preferably 30 g / 100 ml or more. As a result, the surface of the conductive material is modified, the adsorption of the copolymer (A) is further strengthened, and the dispersion stability of the dispersion is improved. The inorganic base is preferably a compound having at least one of an alkali metal and an alkaline earth metal, and more particularly, chlorides, hydroxides, carbonates and nitrates of alkali metals and alkaline earth metals. Examples thereof include sulfates, phosphates, tungstates, vanadium salts, molybdates, niobates, borates and the like. Among these, alkali metals, chlorides of alkaline earth metals, hydroxides and carbonates are preferable in terms of easily supplying cations. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. Examples of the carbonate of the alkali metal include lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and the like. Further, as a base containing no metal, ammonia can be mentioned. Of these, lithium hydroxide and sodium hydroxide are more preferable. The metal contained in the inorganic base and the inorganic metal salt of the present invention may be a transition metal.

Examples of the organic base include primary, secondary, tertiary or quaternary alkylamines having an alkyl group having 1 to 40 carbon atoms which may be substituted.

Examples of the primary alkylamine having an alkyl group having 1 to 40 carbon atoms substituted include methylamine, ethylamine, propylamine, butylamine, isobutylamine, 2-ethylhexylamine, laurylamine, stearylamine, oleylamine, and 2 -Aminoethanol, 3-aminopropanol, 3-ethoxypropylamine and the like can be mentioned.

Examples of the secondary alkylamine having an alkyl group having 1 to 40 carbon atoms which may be substituted include dimethylamine, diethylamine, dipropylamine, 2-methylaminoethanol and the like.

Examples of the tertiary alkylamine having an alkyl group having 1 to 40 carbon atoms which may be substituted include trimethylamine, triethylamine, 2- (dimethylamino) ethanol and the like.

Examples of the quaternary alkylamine having an alkyl group having 1 to 40 carbon atoms which may be substituted include tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethyl (2-hydroxyethyl) ammonium hydroxide and the like.

Of these, primary, secondary, tertiary or quaternary alkylamines having an optionally substituted alkyl group having 1 to 10 carbon atoms are preferable, and an optionally substituted alkyl group having 1 to 5 carbon atoms is used. Primary, secondary, tertiary or quaternary alkylamines having are more preferred.
Further, the alkyl group which may be substituted means that a hydrogen atom may be substituted, and examples of the substituent include a hydroxy group and the like.

Examples of the organic base include 1,8-diazabicyclo [5.4.0] undecene-7 (DBU), 1,5-diazabicyclo [4.3.0] nonen-5 (DBN), and 1,4-diazabicyclo [2]. .2.2] Compounds containing a basic nitrogen atom such as octane (DABCO), tri-n-butylamine, dimethylbenzylamine, monoethanolamine, imidazole, and 1-methylimidazole may be used.

The conductive material dispersion of the present embodiment preferably has a solid content mass ratio (B) / (A) of the copolymer (A) and the base (B) of 0.2 to 1.0. 0.2 to 0.5 is more preferable, and 0.2 to 0.4 is even more preferable.

In the conductive material dispersion of the present embodiment, the conductive material is placed in a dispersant carrier such as a dispersant and a binder resin and / or a dispersion medium in a kneader, a two-roll mill, a three-roll mill, a ball mill, a horizontal sand mill, and a vertical type. It can be finely dispersed and manufactured by using various dispersion means such as a sand mill, an annual bead mill, a high pressure jet mill, or an attritor. At this time, two or more kinds of objects to be dispersed may be simultaneously dispersed in the carrier and / or dispersion medium to be dispersed, or separately dispersed substances may be mixed.

The solid content of the conductive material dispersion of the present embodiment is preferably 0.1 to 2% by mass, more preferably 0.2 to 1% by mass, based on 100% by mass of the conductive material dispersion.

The total amount of the copolymer (A) and the base (B) in the conductive material dispersion of the present embodiment is 1000% by mass or less when used for a transparent antistatic paint with respect to 100% by mass of the conductive material. It is preferable, 600% by mass or less is more preferable, and 500% by mass or less is particularly preferable. Further, 100% by mass or more is preferable, and 200% by mass or more is more preferable. When used in a secondary battery, it is preferably 200% by mass or less, more preferably 100% by mass or less. Further, 20% by mass or more is preferable, and 30% by mass or more is more preferable. Within the above range, the conductive material can be present in a good and stable manner without impairing the application characteristics.

The pH of the conductive material dispersion of the present embodiment is preferably 9.0 to 13.5, more preferably 10.0 to 13.0 in the dispersion step.

The 50% particle size (D50) calculated by the laser diffraction type particle size distribution measurement of the conductive material dispersion of the present invention is preferably 1.5 to 40 μm, more preferably 10 to 30 μm.

The conductive material dispersion of the present embodiment preferably includes a neutralization step of mixing an acid after dispersing at the above pH. The acid used is preferably an acid having a pKa of 2 or more at 25 ° C. in water. For example, acetic acid, phosphoric acid, carbonic acid and the like can be mentioned.

The conductive material dispersion of the present embodiment preferably has a pH of 8.0 to 13.0, more preferably 8 to 10.

<Composition for secondary battery electrodes>
The composition for a secondary battery electrode of the present invention preferably contains the above-mentioned conductive material dispersion and a binder resin. The composition for a secondary battery electrode can be produced by mixing a conductive material dispersion and a binder resin. Any component may be further mixed together with the conductive material dispersion and the binder resin. The composition for the secondary battery electrode contains water, and may optionally contain the water-soluble solvent exemplified as the dispersion medium of the conductive material.

<Binder resin used in the composition for secondary battery electrodes>
The binder resin used in the composition for the secondary battery electrode is not particularly limited as long as it is usually used as the binder resin for the paint, and can be appropriately selected depending on the intended purpose. Further, the binder resin used in the composition for the secondary battery electrode is a resin capable of bonding between substances such as an active material and a conductive material, and is different from the dispersant of the present invention in the present specification. The binder resin used in the composition for the secondary battery electrode is, for example, ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylonitrile, styrene, vinyl. Polymers or copolymers containing butyral, vinyl acetal, vinyl pyrrolidone, etc. as constituent units; polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, acrylic resin, formaldehyde resin, Silicon resins, fluororesins; cellulose resins (eg, carboxymethyl cellulose (CMC)); styrene-butadiene rubbers, elastomers such as fluororubbers; conductive resins such as polyaniline, polyacetylene and the like. Further, modified products and mixtures of these resins and copolymers may be used. Among these, when used as a binder resin for a positive electrode, a polymer or copolymer having a fluorine atom in the molecule, for example, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene, or the like is preferable from the viewpoint of resistance. When used as a binder resin for the negative electrode, carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, etc., which have good adhesion, are preferable.

The content of the binder resin used in the composition for the secondary battery electrode is preferably 0.5 to 30% by mass, more preferably 0.5 to 25% by mass, based on the non-volatile content of the resin composition.

The composition for a secondary battery electrode may contain a positive electrode active material or a negative electrode active material. In the present specification, the positive electrode active material and the negative electrode active material may be simply referred to as “active material”. The active material is a material that is the basis of a battery reaction. The active material is divided into a positive electrode active material and a negative electrode active material according to the electromotive force. In the present specification, when the composition for a secondary battery electrode containing a positive electrode active material or a negative electrode active material is referred to as a "positive electrode mixture composition", a "negative electrode mixture composition", or simply a "mixture composition", respectively. There is. The mixture composition is preferably in the form of a slurry in order to improve uniformity and processability. The mixture composition contains at least the conductive material dispersion and the active material, or at least the conductive material dispersion, the binder resin and the active material. In the present specification, the mixture composition may be referred to as "mixture slurry".

<Positive electrode active material>
The positive electrode active material is not particularly limited, but for example, for secondary battery applications, metal compounds such as metal oxides and metal sulfides capable of reversibly doping or intercalating lithium ions can be used. For example, lithium manganese composite oxide (eg Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), lithium nickel composite oxide (eg Li _x NiO ₂ ), lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel cobalt. composite oxides (e.g., _{Li x Ni 1-y Co y} O 2), lithium manganese cobalt composite oxides (e.g., _{Li x Mn y Co 1-y} O 2), lithium nickel manganese cobalt composite oxide (e.g., _Li x Ni _y having _{Co z Mn 1-y-z} O 2), spinel type lithium-manganese-nickel composite oxide (e.g., _{Li x Mn 2-y Ni y} O 4) a composite oxide of lithium and a transition metal, such as powders, an olivine structure Lithium phosphorus oxide powder (eg Li _x FePO ₄ , Li _x Fe _1-y Mn _y PO ₄ , Li _x CoPO _4, etc.), manganese oxide, iron oxide, copper oxide, nickel oxide, vanadium oxide (eg V ₂ O) ₅ , V ₆ O ₁₃ ), transition metal oxide powders such as titanium oxide, transition metal sulfide powders such as _{iron sulfate (Fe 2} (SO ₄ ) ₃ ), TiS _{2 and FeS.} However, x, y, and z are numbers, and 0 <x <1, 0 <y <1, 0 <z <1, 0 <y + z <1. These positive electrode active materials may be used alone or in combination of two or more.

<Negative electrode active material>
The negative electrode active material is not particularly limited, but is, for example, a metal Li capable of reversibly doping or intercalating lithium ions, or an alloy thereof, a tin alloy, a silicon alloy negative electrode, Li _X TIO ₂ , Li _X Fe ₂ O ₃ , Li _X Fe ₃ O ₄ , Li _X WO _{2 and} other metal oxides, polyacetylene, poly-p-phenylene and other conductive polymers, graphitized carbon materials and other artificial graphite, or natural graphite and other carbonaceous materials. A powder or resin calcined carbon material can be used. However, x is a number, and 0 <x <1. These negative electrode active materials may be used alone or in combination of two or more.

The content of the conductive material in the mixture composition is preferably 0.01% by mass or more based on the mass of the active material (assuming the mass of the active material is 100% by mass). , 0.02% by mass or more, more preferably 0.03% or more. Further, it is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less.

The content of the dispersant in the mixture composition is preferably 0.01% by mass or more, preferably 0.02% by mass or more, based on the mass of the active material (assuming the mass of the active material is 100% by mass). Is more preferable. Further, it is preferably 10% by mass or less, and more preferably 5% by mass or less.

When the mixture composition contains a binder resin, the content of the binder resin in the mixture composition is 0.5% by mass or more based on the mass of the active material (assuming the mass of the active material is 100% by mass). Is preferable. Further, it is preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less.

The solid content in the mixture composition is preferably 30% by mass or more, preferably 40% by mass or more, based on the mass of the mixture composition (assuming the mass of the mixture composition is 100% by mass). Is more preferable. Further, it is preferably 90% by mass or less, and more preferably 80% by mass or less.

The mixture composition can be produced by various conventionally known methods. For example, a method of adding an active material to a conductive material dispersion; a method of adding a binder resin after adding an active material to a conductive material dispersion; a method of adding a binder resin to a conductive material dispersion. , A method of adding an active material to produce the substance, and the like. As a method for producing the mixed material composition, a method of adding a binder resin to the conductive material dispersion and then further adding an active material to disperse the mixture is preferable. The dispersion device used for dispersion is not particularly limited. A mixture composition can be obtained by using the dispersion means mentioned in the description of the conductive material dispersion. Therefore, as a method for producing the mixed material composition, a treatment may be performed in which the active material is added and dispersed without adding the binder resin to the conductive material dispersion.

<Electrode film>
The electrode film includes at least one selected from the group consisting of a film formed by using the conductive material dispersion and a film formed by using the composition for a secondary battery electrode. The electrode membrane may further include a current collector. The electrode film can be obtained, for example, by applying a composition for a secondary battery electrode on a current collector and drying it, and the current collector includes a film. An electrode film formed by using the positive electrode mixture composition can be used as the positive electrode. An electrode film formed by using the negative electrode mixture composition can be used as the negative electrode. In the present specification, a film formed by using a composition for a secondary battery electrode containing an active material may be referred to as an “electrode mixture layer”.

The material and shape of the current collector used to form the electrode film are not particularly limited, and those suitable for various secondary batteries can be appropriately selected. Examples of the material of the current collector include conductive metals or alloys such as aluminum, copper, nickel, titanium, and stainless steel. As the shape, a flat foil is generally used, but a current collector having a roughened surface, a perforated foil-shaped current collector, and a mesh-shaped current collector can also be used. The thickness of the current collector is preferably about 0.5 to 30 μm.

The method for applying the conductive material dispersion or the composition for the secondary battery electrode on the current collector is not particularly limited, and a known method can be used. Specific examples thereof include a die coating method, a dip coating method, a roll coating method, a doctor coating method, a knife coating method, a spray coating method, a gravure coating method, a screen printing method, an electrostatic coating method and the like. Examples of the drying method include leaving drying or drying using a blower dryer, a warm air dryer, an infrared heater, a far infrared heater, or the like, but the drying method is not particularly limited thereto.

After coating, rolling may be performed by a lithographic press, a calendar roll, or the like. The thickness of the formed film is, for example, 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less.

The film formed by using the conductive material dispersion or the composition for the secondary battery electrode is used to improve the adhesion between the electrode mixture layer and the current collector, or to improve the conductivity of the electrode film. It can also be used as a base layer for the material layer.

<Secondary battery>
The secondary battery includes a positive electrode, a negative electrode, and an electrolyte, and at least one selected from the group consisting of a positive electrode and a negative electrode includes the electrode film.

As the electrolyte, various conventionally known electrolytes in which ions can move can be used. For example, 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 (where Ph is a phenyl group) and the like, including, but not limited to, those containing lithium salts. The electrolyte is preferably dissolved in a non-aqueous solvent and used as an electrolytic solution.

The non-aqueous solvent is not particularly limited, and is, for example, carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; γ-butyrolactone, γ-valerolactone, and γ. -Lactones such as octanoic lactones; tetrahydrofuran, 2-methyltetrachloride, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1, Glymes such as 2-dibutoxyetane; esters such as methylformate, methylacetate, and methylpropionate; sulfoxides such as dimethylsulfoxide and sulfolane; and nitriles such as acetonitrile. Each of these solvents may be used alone, or two or more kinds may be mixed and used.

The non-aqueous electrolyte secondary battery preferably contains a separator. Examples of the separator include, but are not limited to, polyethylene non-woven fabric, polypropylene non-woven fabric, polyamide non-woven fabric, and non-woven fabric obtained by subjecting them to a hydrophilic treatment.

The structure of the non-aqueous electrolyte secondary battery of the present embodiment is not particularly limited, but usually includes a positive electrode and a negative electrode, and a separator provided as needed, and is used as a paper type, a cylindrical type, a button type, a laminated type, or the like. It can be made into various shapes according to the purpose to be used.

<Conductive paint>
The conductive coating material of the present embodiment further contains at least a binder for coating material in the conductive material dispersion.

The binder for paint is not particularly limited as long as it is usually used as a binder resin for paint, and can be appropriately selected depending on the intended purpose. For example, a condensed synthetic resin, an additive synthetic resin, or a natural high molecular weight resin. Molecular compounds, etc. may be mentioned. Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, silicon resin and the like. Examples of the additive synthetic resin include a polyolefin resin, a polystyrene resin, a polyvinyl alcohol resin, a polyvinyl ester resin, a polyacrylic acid resin, an unsaturated carboxylic acid resin and the like.
Examples of the natural polymer compound include celluloses, rosins, and natural rubbers.
The resin may be used as a homopolymer, may be used as a copolymer and may be used as a composite resin, and any of a single-phase structure type, a core-shell type, and a power feed type emulsion can be used.

As the binder for paint, a binder in which the resin itself has a hydrophilic group and has self-dispersibility can be used, and a binder in which the resin itself does not have dispersibility and is imparted with a surfactant or a resin having a hydrophilic group and has dispersibility can be used. Among these, emulsions of resin particles obtained by emulsification and suspension polymerization of ionomers of polyester resins and polyurethane resins and unsaturated monomers are suitable. In the case of emulsion polymerization of an unsaturated monomer, the reaction is carried out with water containing an unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, a pH adjuster, etc. to carry out a resin emulsion. Therefore, a binder for paint can be easily obtained, and the resin composition can be easily changed, so that the desired properties can be easily created.

Examples of the unsaturated monomer include unsaturated carboxylic acids, (meth) acrylic acid ester monomers, (meth) acrylic acid amide monomers, aromatic vinyl monomers, and vinyl cyano compounds. A body, a vinyl monomer, an allyl compound monomer, an olefin monomer, a diene monomer, an oligomer having an unsaturated carbon, and the like can be used alone or in combination of two or more. By combining these monomers, it is possible to flexibly modify the properties, and it is also possible to modify the properties of the resin by carrying out a polymerization reaction or a graft reaction using an oligomer-type polymerization initiator.

Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid and the like.
Examples of the monofunctional (meth) acrylic acid esters include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, and 2-ethylhexyl methacrylate. , Octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methacryloxyethyl trimethylammonium salt, 3 -Methacryloxypropyltrimethoxysilane, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl. Examples thereof include acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dimethylaminoethyl acrylate, acryloxyethyl trimethylammonium salt, and the like. ..

Examples of the polyfunctional (meth) acrylic acid esters include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, and 1,4-butylene. Glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) )
Propane, trimethylolpropane trimethacrylate, trimethylolethanetrimethacrylate, polyethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol di Acrylate, Neopentyl Glycol Diacrylate, 1,9-Nonandiol Diacrylate, Polypropylene Glycol Diacrylate, 2,2'-Bis (4-Acryloxipropyroxyphenyl) Propane, 2,2'-Bis (4-Acryloxy) Diethoxyphenyl) Propanetrimethylolpropanetriacrylate, trimethylolethanetriacrylate, tetramethylolmethanetriacrylate, ditrimethyloltetraacrylate, tetramethylolmethanetetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and the like can be mentioned.

Examples of the (meth) acrylic acid amide monomers include acrylamide, methacrylamide, N, N-dimethylacrylamide, methylenebisacrylamide, 2-acrylamide-2-methylpropanesulfonic acid and the like.
Examples of the aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorstyrene, vinylanisole, vinylnaphthalene, divinylbenzene and the like.

Examples of the vinyl cyano compound monomers include acrylonitrile and methacrylonitrile.
Examples of the allyl compound monomers include allylsulfonic acid or a salt thereof, allylamine, allyl chloride, diallylamine, diallyldimethylammonium salt and the like.
Examples of the olefin monomers include ethylene and propylene.
Examples of the diene monomers include butadiene and chloroprene.
Examples of the vinyl monomers include vinyl acetate, vinylidene chloride, vinyl chloride, vinyl ether, vinyl ketone, vinylpyrrolidone, vinyl sulfonic acid or a salt thereof, vinyl trimethoxysilane, vinyl triethoxysilane and the like.

Examples of the oligomer having unsaturated carbon include a styrene oligomer having a methacryloyl group, a styrene-acrylonitrile oligomer having a methacryloyl group, a methylmethacrylate oligomer having a methacryloyl group, a dimethylsiloxane oligomer having a methacryloyl group, and a polyester having an acryloyl group. Examples thereof include oligomers.

As a specific example of such a binder for paint, as a urethane resin, Dai-ichi Kogyo Seiyaku Co., Ltd .: Superflex 110, Superflex 150, Superflex 210, Superflex 300, Superflex 420, Superflex 460, Super Flex 470, Super Flex 500M, Super Flex 620, Super Flex 650, Super Flex 740, Super Flex 820, Super Flex 840, F-8082D, F-2951D, manufactured by Sumika Bayer Urethane Co., Ltd .: Bihydrol UH2606, Bihydrol UH650, Bihydrol UHXP2648, Bihydrol UHXP2650, Implanil DLC-F, Implanil DLN, Implanil DLP-R, Implanil DLS, Implanil DLU, Implanil XP2611, Implanil LPRSC1380, Impranil LPRSC1380, Implanil LPRSC1537, Implanil LPRSC15 Impranil LPDSB1069, manufactured by Dainippon Ink and Chemicals Co., Ltd .: Hydran HW-301, HW-310, HW-311, HW-321B, HW-333, HW-340, HW-350, HW-375, HW-920 , HW-930, HW-940, HW-950, HW-970, AP-10, AP-20, ECOS3000, manufactured by Sanyo Kasei Kogyo Co., Ltd .: UCOAT UWS-145, Permarin UA-150, Permarin UA-200, Permarin UA-300, Permarin UA-310, Eucoat UX-320, Permarin UA-368, Permarin UA-385, Eucoat UX-2510, manufactured by Nikka Kagaku Co., Ltd .: Neo Sticker 100C, Evafanol HA-107C, Evafanol HA- 50C, Evafanol HA-170, Evafanol HA-560, manufactured by ADEKA Corporation: Adeka Bontita UHX-210, Adeka Bontita UHX-280 and the like. As polyolefin resin, Mitsubishi Chemical Corporation: APPPLOK series BW-5550, Toyobo Co., Ltd .: HARDLEN series EH-801, EW-5303, EW-5504, EW-5515, EW-8511, EZ-1000, EZ -2000, manufactured by Nippon Paper Industries, Ltd .: Supercron series E-480T, E-415, E-412T, S-6375, S-6377 and the like. Examples of the alkyd resin include S118, S126 and S346 of the water sol series manufactured by Dainippon Ink Co., Ltd., 376 and 580 of the Arolon series manufactured by Nippon Shokubai Co., Ltd., and ARL581 and ARL580 of the Acryset series manufactured by Nippon Shokubai Co., Ltd.

The coating material of the present invention is a melamine resin, a urea resin, a polyisocyanate compound, a blocked polyisosianate compound, an epoxy compound or a resin, or a carboxyl group-containing compound, which has a role as a cross-linking agent capable of reacting with a functional group of a coating binder. Alternatively, a resin, an acid anhydride, an alkoxysilane group-containing compound, a resin, or the like can be used. It is desirable to use a resin containing a crosslinkable functional group and a resin having a role as a crosslinker in combination, and among them, one selected from acrylic resin, polyester resin, alkyd resin, melamine resin, epoxy resin and urea resin is used. It is more preferable to use one selected from an acrylic resin, a polyester resin, an alkyd resin and a melamine resin, and it is more preferable to use an acrylic resin and a melamine resin in combination.

The melamine resin is particularly preferably used because it has thermosetting properties and acts as a curing agent. The acrylic resin is preferably obtained by polymerizing a monomer having a polymerizable unsaturated double bond, which is well known to those skilled in the art, by a conventional method. Examples of the monomer having a polymerizable unsaturated double bond include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, etacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, maleic anhydride and fumaric acid. Carboxylic acid group-containing monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxyl group-containing monomer such as ε-caprolactone-modified acrylic monomer, (meth) acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, (meth) ) 2-Ethylhexyl acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate and other (meth) acrylic acid ester monomers , Styrene, α-methylstyrene, α-methylstyrene dimer, vinyltoluene, divinylbenzene and other styrene-based monomers. Further, it is preferable to use a radical polymerization initiator or the like well known to those skilled in the art for polymerization.

Specific examples of the melamine resin include Cymel 300, 303, 325, 327, 350, 370 (manufactured by Mitsui Cytec Co., Ltd.), Nicarac MS15, MS17, MX430, MX650 (manufactured by Sanwa Chemical Co., Ltd.), and the like. Methyl etherified melamine resins such as Sumimar M-55 (manufactured by Sumitomo Chemical Co., Ltd.), Regimin 740, 741 (manufactured by Monsanto); Methyl ether / butyl ether mixed etherified melamine resin such as Nicarac MX485, MX487 (manufactured by Sanwa Chemical Co., Ltd.), Regimin 755 (manufactured by Monsanto Co., Ltd.). These melamine resins can be used alone or as a mixture of two or more.

Further, the conductive coating material of the present invention includes water or an organic solvent, a rheology control agent, a pigment dispersant, an antioxidant, a curing catalyst, an antifoaming agent, an antioxidant, an ultraviolet absorber, and a surface conditioner, if necessary. , Various additives such as preservatives, extender pigments and the like can be appropriately blended.

The content of the conductive material in the conductive coating material is preferably 0.005% by mass or more, preferably 0.01% by mass, and 0.02 based on the mass in the total solid content of the coating material. More preferably, it is by mass or more. Further, it is preferably 0.20% by mass or less, and more preferably 0.1% by mass or less.

The conductive coating material of the present invention can be prepared by mixing and dispersing the above-mentioned components. Further, the conductive material dispersion can be prepared in advance by mixing with the above resin component and water, and the conductive material dispersion can be mixed with the above-mentioned component and blended in the conductive paint.

<Conductive coating film>
The conductive coating film of the present invention is obtained by applying the conductive paint to a substrate and drying it. It is not particularly limited and can be applied to various base materials, for example, metal base materials such as iron, stainless steel, aluminum and its surface-treated products; cement-based base materials such as cements, limes and plasters; polyvinyl chloride. Types, polyesters, polycarbonates, acrylics and other plastic-based substrates and the like can be mentioned. In addition, various objects to be coated in the field of building / building materials such as building materials, buildings, and structures made of these various base materials can be mentioned.

The method for applying the conductive coating material is not particularly limited, and examples thereof include brush coating, roller coating, and spray coating. After coating, a coating film can usually be obtained by drying at room temperature or heating. The coating amount; coating order such as undercoating, intermediate coating, and topcoating; coating film thickness; drying time and the like can be arbitrarily set according to the type of the conductive coating material and the base material to be applied.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the examples, "carbon nanotubes" may be abbreviated as "CNT". Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

(Measuring method of acid value of dispersant)
The acid value of the dispersant was calculated from the titration of the dispersant / NMP solution. 1 g of the dispersant was collected in a beaker (100 ml), 30 ml of NMP was added, and the mixture was stirred with a stirrer to dissolve. Further, it was diluted with 20 ml of ion-exchanged water to obtain a titrated constant solution. The titrated solution is separately titrated with a 0.1 mol / l KOH / ethanol solution using a potential difference automatic titrator (AT-710S, manufactured by Kyoto Denshi Kogyo), and the acid value of the dispersant is determined from the titration at the isoelectric point. mgKOH / g) was calculated.

(Measuring method of weight average molecular weight (Mw))
The weight average molecular weight (Mw) of the synthesized dispersant was measured by gel permeation chromatography (GPC) equipped with an RI detector.
The device used HLC-8320GPC (manufactured by Tosoh), three separation columns were connected in series, and the fillers were "TSK-GELSUPER AW-4000", "AW-3000", and "AW-2500" manufactured by Tosoh in order. Was measured at an oven temperature of 40 ° C., a solution of 30 mM triethylamine and 10 mM LiBr in N, N-dimethylformamide as an eluent at a flow rate of 0.6 ml / min. The sample was prepared in a solvent consisting of the above eluent at a concentration of 1 wt%, and 20 microliters were injected. The molecular weight is a polystyrene-equivalent value.

(Method of measuring specific surface area of conductive material)
The conductive material was weighed at 0.03 g using an electronic balance (MSA225S100DI manufactured by Sartorius), and then dried at 110 ° C. for 15 minutes while degassing. ^{Then, the specific surface area (m 2} / g) of the conductive material was measured using a fully automatic specific surface area measuring device (HM-model 1208 manufactured by MOUNTECH).

(Measuring method of dispersed particle size of conductive material dispersion)
The dispersion particle size was determined by a determination method according to JIS K5600-2-5 using a grind gauge having a maximum groove depth of 300 μm.

(Method for measuring the particle size of the median diameter of the conductive material dispersion)
For the particle size distribution of the conductive material dispersion, a 50% particle size (Median diameter, D50) was calculated from a laser diffraction type particle size distribution (“Microtrack MT3000II” manufactured by Microtrac Bell).

<Synthesis of copolymer>
(Synthesis Example 1)
(Synthesis of copolymer 1)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer is charged with 100 parts of methyl ethyl ketone, 90.0 parts of acrylonitrile, 10.0 parts of acrylic acid, and 0.5 parts of 3-mercapto-1,2-propanediol. , Replaced with nitrogen gas. The inside of the reaction vessel is heated to 70 ° C. to prepare a mixture consisting of 10 parts of methyl ethyl ketone and 0.4 part of 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: V-65). It was dropped into a reaction vessel over a long period of time to carry out a polymerization reaction. After completion of the dropping, the mixture was reacted at 70 ° C. for 1 hour, 0.1 part of V-65 was added, and the reaction was further continued at 70 ° C. for 1 hour to obtain the desired product as a precipitate. After that, it was confirmed by measuring the non-volatile content that the conversion rate exceeded 98%. The product was filtered off by vacuum filtration, washed with 100 parts of ethyl acetate, and dried under reduced pressure to completely remove the solvent to obtain a copolymer (A-1). The weight average molecular weight (Mw) of the copolymer (A-1) was 52,000. The acid value was 78 mgKOH / g.

(Synthesis Examples 2 to 23)
(Synthesis of copolymers 2 to 23)
The copolymers 2 to 23 were produced in the same manner as in Synthesis Example 1 except that the monomers and chain transfer agents used were changed according to Table 1. The weight average molecular weight (Mw) of each dispersant was as shown in Table 1. For the synthesis of the copolymer, Mw was prepared by appropriately changing the addition of the chain transfer agent, the adjustment of the amount of the polymerization initiator, the reaction conditions and the like.

AA: Acrylic acid IA: Itaconic acid SAMA: 2-methacryloyloxyethyl succinate β-CEA: β-carboxyethyl acrylate a-1: Isopropyl alcohol adduct of maleic anhydride (formula (1) below)
a-2: 2-acryloyloxyethyl succinate a-3: Octenyl succinic anhydride adduct of hydroxyethyl acrylate (formula (2) below)
HEA: Hydroxyethyl acrylate DMAEA: Dimethylaminoethyl acrylate BA: Butyl acrylate 2EHA: 2-Ethylhexyl acrylate

<Example α: Application to secondary battery>

(Preparation of conductive material dispersion)
(Example 1α-1)
According to the composition shown in Table 2, ion-exchanged water, a copolymer, a base and an antifoaming agent were added to the stainless steel container, and the mixture was stirred with a disper until uniform. After that, the conductive material was added while stirring with a disper, and a square hole high shea screen was attached to a high shea mixer (L5MA, manufactured by SILVERSON). Dispersed until the value was 250 μm or less. Further, a high-pressure homogenizer (Starburst Lab HJP-17007, manufactured by Sugino Machine Limited) was used for dispersion treatment. A single nozzle chamber was used for the dispersion treatment, and a 20-pass treatment was performed at a nozzle diameter of 0.25 mm and a pressure of 100 MPa to obtain a dispersion. The median diameter of the dispersion was measured and confirmed to be 100 μm or less. A 10 mass% acetic acid aqueous solution and water were appropriately added to the obtained dispersion and stirred to obtain a conductive material dispersion (dispersion 1α) having a pH of 9.5 and a conductive material content of 0.25%. As shown in Table 2, the dispersion 1α had a low viscosity and good storage stability.

(Examples 1α-2 to 1α-30, Comparative Examples 1α-1 to 1α-6)
According to the composition shown in Table 2, each dispersion (dispersion 2α to 30α, comparative dispersion 1α to 6α) was obtained in the same manner as in Example 1α-1. However, when the median diameter was 100 μm or more, an additional 2-pass dispersion treatment was performed, measurement was performed again, and the measurement was repeated until the median diameter became 100 μm or less. A 10 mass% acetic acid aqueous solution and water were appropriately added to the obtained dispersion and stirred to obtain a conductive material dispersion having a pH of 9.5 and a conductive material content of 0.25%. However, when the obtained dispersion was 9.5 or less, it was diluted with water only. As shown in Table 2, all of the conductive material dispersions (dispersions 2α to 30α) of the present invention had low viscosity and good storage stability.

(Method for measuring viscosity of conductive material dispersion)
To measure the viscosity, use a B-type viscometer (“BL” manufactured by Toki Sangyo), stir the dispersion sufficiently with a spatula at a dispersion temperature of 25 ° C, and then set the rotor rotation speed of the B-type viscometer to 60 rpm. I went immediately. The rotor used for the measurement was No. 1 when the viscosity was less than 100 mPa · s. If 1 is 100 or more and less than 500 mPa · s, No. If 2 is 500 or more and less than 2,000 mPa · s, No. If 3 is 2,000 or more and less than 10,000 mPa · s, No. The ones of 4 were used respectively. The lower the viscosity, the better the dispersibility, and the higher the viscosity, the poorer the dispersibility. If the obtained dispersion was clearly separated or settled, it was regarded as poor dispersibility.
Judgment criteria ◎: Less than 500 mPa · s (excellent)
◯: 500 mPa ・ s or more and less than 2,000 mPa ・ s (good)
Δ: 2,000 mPa ・ s or more and less than 10,000 mPa ・ s (possible)
×: 10,000 mPa · s or more, settling or separation (defective)

(Stability evaluation method for conductive material dispersion)
To evaluate the storage stability, the viscosity of the dispersion after standing at 50 ° C. for 7 days and storing it was measured. The measuring method was the same as the initial viscosity.
Judgment criteria ◎: Initial equivalent (excellent)
◯: Viscosity changed slightly (good)
Δ: Viscosity has increased, but gelation has not occurred (possible)
×: Gelled (defective)

The abbreviations shown in Table 2 mean the following.
<Conductive material>
-TUBALL (80%): OCSiAl, single-wall carbon nanotube, average outer diameter: 1.5 nm, carbon component 80%, specific surface area 490 m ² / g
-TUBALL (93%): OCSiAl, single-wall carbon nanotube, average outer diameter: 1.5 nm, carbon component 93%, specific surface area 850 m ² / g
6A: JENOTUBE6A (manufactured by JEIO, multi-wall carbon nanotubes, outer diameter 5-7 nm, specific surface area 700 m ² / g)
100T: K-Nanos 100T (manufactured by Kumho Petrochemical, multi-wall carbon nanotubes, outer diameter 10 to 15 nm, specific surface area 240 m ² / g)
<Base>
-LiOH: Lithium hydroxide (manufactured by Kishida Chemical Co., Ltd., pKb = -0.36, solubility 22 g / 100 ml)
TEA-OH: 10% aqueous solution of tetraethylammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd., pKb = 0.10, solubility 10 g / 100 g or more)
-KOH: Potassium hydroxide (manufactured by Kishida Chemical Co., Ltd., pKb = 0.50, solubility 110 g / 100 ml)
-DPA: Dipropylamine (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., pKb = 3.09, solubility 3.5 g / 100 ml)
_{-NH 3} : 25% aqueous solution of ammonia (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., pKb = 4.70, solubility 89.9 g / 100 ml)
-Ca (OH) ₂ : Calcium hydroxide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., pKb = 1.40, solubility 0.17 g / 100 ml)
-TEA: Triethanolamine (Tokyo Chemical Industry, pKb = 6.2, solubility 10 g / 100 ml or more)

(Preparation of negative electrode mixture composition and negative electrode)
(Example 2α-1)
After adding the dispersion (dispersion 1α), CMC, and water to a plastic container with a capacity of 150 cm ³ , a rotation / revolution mixer (Sinky Awatori Rentaro, ARE-310) is used at 2,000 rpm. The mixture was stirred for 30 seconds. Then, artificial graphite and silicon were added as active materials, and the mixture was stirred at 2,000 rpm for 150 seconds using the above-mentioned rotation / revolution mixer. After that, SBR was added, and the mixture was stirred at 2,000 rpm for 30 seconds using the above-mentioned rotation / revolution mixer to obtain a negative electrode mixture composition. The non-volatile content of the negative electrode mixture composition is 48% by mass. The non-volatile content ratio of artificial graphite: silicon: CNT: CMC: SBR in the negative electrode mixture composition was 87: 10: 0.5: 1: 1.5.

The obtained negative electrode mixture composition is applied onto a copper foil having a thickness of 20 μm using an applicator, and then the coating film is dried in an electric oven at 120 ° C. ± 5 ° C. for 25 minutes to form an electrode film. Was produced. Then, the electrode film was rolled by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to obtain a negative electrode (negative electrode 1). The basis weight per unit of the mixed material layer was 10 mg / cm ² , and the density of the mixed material layer after the rolling treatment was 1.6 g / cc.

-Artificial graphite: CGB-20 (manufactured by Nippon Graphite Industry), 100% non-volatile content
-Silicon: Silicon monoxide (manufactured by Osaka Titanium Technologies, SILICON MONOOXIDE SiO 1.3C 5 μm), 100% non-volatile content
-CMC: Carboxymethyl cellulose # 1190 (manufactured by Daicel FineChem), 100% non-volatile content
-SBR: Styrene butadiene rubber TRD2001 (manufactured by JSR), non-volatile content 48%

(Examples 2α-2 to 2α-30, Comparative Examples 2α-1 to 2α-6)
Using each dispersion (dispersion 2α to 30α), negative electrodes 2 to 30 and comparative negative electrodes 1 to 6 were obtained by the same method as in Example 2α-1.

(Method for evaluating the conductivity of the negative electrode)
The surface resistivity (Ω / □) of the mixture layer of the obtained negative electrode was measured using Mitsubishi Chemical Analytech: Lorester GP, MCP-T610. After the measurement, the thickness of the mixture layer was multiplied to obtain the volume resistivity (Ω · cm) of the negative electrode. For the thickness of the mixture layer, the film thickness of the copper foil is subtracted from the average value measured at three points in the electrode using a film thickness meter (DIKON, DIGIMICRO MH-15M), and the volume resistivity of the negative electrode ( Ω · cm).
Judgment criteria ◎: Less than 0.3Ω ・ cm (excellent)
◯: 0.3Ω ・ cm or more and less than 0.5Ω ・ cm (good)
×: 0.5Ω ・ cm or more (defective)

(Adhesion evaluation method for negative electrode)
Two of the obtained negative electrodes were cut into a rectangle of 90 mm × 20 mm with the coating direction as the major axis. A desktop tensile tester (Strograph E3, manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used to measure the peel strength, and the peel strength was evaluated by a 180-degree peel test method. Specifically, a 100 mm × 30 mm size double-sided tape (No. 5000NS, manufactured by Nitoms) was attached on a stainless steel plate, and the mixed material layer side of the produced negative electrode was brought into close contact with the other side of the double-sided tape for a test sample. And said. Next, the test sample was fixed vertically so that the short sides of the rectangle came up and down, and the end of the copper foil was peeled off while pulling from the bottom to the top at a constant speed (50 mm / min), and the average value of the stress at this time. Was taken as the peel strength.
Judgment criteria ◎: 0.5 N / cm or more (excellent)
◯: 0.1 N / cm or more and less than 0.5 N / cm (good)
X: Less than 0.1 N / cm (defective)

(Preparation of mixture composition for positive electrode and positive electrode)
(Example 3α-1)
After adding a conductive material dispersion (dispersion 1α), PTFE, CMC and water to a plastic container with a capacity of 150 cm ^{3, a rotation / revolution mixer (Sinky Awatori Rentaro, ARE-310) is used at 2000 rpm.} After stirring for 30 seconds, LFP was added as an active material, and the mixture was stirred at 2000 rpm for 150 seconds using a rotation / revolution mixer (Awatori Rentaro manufactured by Shinky, ARE-310). Further, after that, water was added, and the mixture was stirred at 2000 rpm for 30 seconds using a rotation / revolution mixer (Awatori Rentaro manufactured by Shinky, ARE-310) to obtain a mixed material composition for a positive electrode. The non-volatile content of the mixture composition for the positive electrode was 75% by mass. The non-volatile content ratio of active material: CNT: PTFE: CMC in the positive electrode mixture composition was 98.5: 0.5: 1.

The positive electrode mixture composition was applied onto an aluminum foil having a thickness of 20 μm using an applicator, and then dried in an electric oven at 120 ° C. ± 5 ° C. for 25 minutes to prepare an electrode film. Then, the electrode film was rolled by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to obtain a positive electrode (positive electrode 1). The basis weight per unit of the mixed material layer was 20 mg / cm ² , and the density of the mixed material layer after the rolling treatment was 2.1 g / cc.

LFP: Lithium iron phosphate HED (trademark) LFP-400 (manufactured by BASF, 100% non-volatile content)
-PTFE: Polytetrafluoroethylene Polyflon PTFE D-210C (manufactured by Daikin, 60% non-volatile content)
-CMC: Carboxymethyl cellulose # 1190 (manufactured by Daicel FineChem, 100% non-volatile content)

(Examples 3α-2 to 3α-30, Comparative Examples 3α-1 to 3α-6)
Using each dispersion (dispersions 2α to 30α), positive electrodes 2 to 30 and comparative positive electrodes 1 to 6 were obtained by the same method as in Example 3α-1.

(Method for evaluating the conductivity of the positive electrode)
The conductivity of the obtained positive electrode was evaluated by the same method as that of the negative electrode except that an aluminum foil was used instead of the copper foil.
Judgment criteria ◎: Less than 10Ω ・ cm (excellent)
〇: 10Ω ・ cm or more and less than 20Ω ・ cm (good)
×: 20Ω ・ cm or more (defective)

(Adhesion evaluation method for positive electrode)
Adhesion was evaluated by the same method as that of the negative electrode, except that the obtained positive electrode was made of aluminum foil instead of copper foil.
Judgment criteria ◎: 1 N / cm or more (excellent)
◯: 0.5 N / cm or more and less than 1 N / cm (good)
×: Less than 0.5 N / cm (defective)

(Preparation of standard positive electrode)
93 parts by mass of LFP (BASF, HED ™ LFP-400, 100% non-volatile content), 4 parts by mass of acetylene black (Denka, Denka Black (registered trademark) HS-100), PTFE: Polytetra as the positive electrode active material After adding 3 parts by mass of fluoroethylene (manufactured by Daikin, 60% by mass of non-volatile content) and CMC to a plastic container having a capacity of 150 ml, the mixture was mixed using a spatula until the powder became uniform. Then, 20.5 parts by mass of water was added, and the mixture was stirred at 2000 rpm for 30 seconds using a rotation / revolution mixer (Awatori Rentaro manufactured by Shinky, ARE-310). Then, the mixture in the plastic container was mixed using a spatula until it became uniform, and the mixture was stirred at 2000 rpm for 30 seconds using the above-mentioned rotation / revolution mixer. After that, 14.6 parts by mass of water was added, and the mixture was stirred at 2000 rpm for 30 seconds using the above-mentioned rotation / revolution mixer. Finally, a high-speed stirrer was used to stir at 3000 rpm for 10 minutes to obtain a standard positive electrode mixture composition.

The above-mentioned standard positive electrode mixture composition is applied on an aluminum foil having a thickness of 20 μm as a current collector using an applicator, and then dried in an electric oven at 120 ° C. ± 5 ° C. for 25 minutes to obtain a unit of electrodes. The basis weight per area was adjusted to ^{20 mg / cm 2.} Further, a rolling process was performed by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to prepare a standard positive electrode having ^{a mixture layer density of 2.1 g / cm 3.}

(Manufacturing of standard negative electrode)
After adding acetylene black (Denka, Denka Black (registered trademark) HS-100), CMC, and water to a plastic container with a capacity of 150 ml, a rotation / revolution mixer (Sinky Awatori Rentaro, ARE-310) Was stirred at 2000 rpm for 30 seconds. Further, artificial graphite (CGB-20 (manufactured by Nippon Graphite Industry)) was added as an active material, and the mixture was stirred at 2000 rpm for 150 seconds using a rotation / revolution mixer (Sinky's Awatori Rentaro, ARE-310). Subsequently, SBR (TRD2001 (manufactured by JSR)) was added, and the mixture was stirred at 2000 rpm for 30 seconds using a rotation / revolution mixer (Sinky's Awatori Rentaro, ARE-310) to obtain a standard negative electrode mixture composition. rice field. The non-volatile content of the standard negative electrode mixture composition was 48% by mass. The non-volatile content ratio of active material: conductive material: CMC: SBR in the standard negative electrode mixture composition was 97: 0.5: 1: 1.5.

The above-mentioned standard negative electrode mixture composition is applied onto a copper foil having a thickness of 20 μm as a current collector using an applicator, and then dried in an electric oven at 80 ° C. ± 5 ° C. for 25 minutes to obtain a unit of electrodes. The basis weight per area was adjusted to ^{10 mg / cm 2.} Further, a rolling process was performed by a roll press (thunk metal, 3t hydraulic roll press) to prepare a standard negative electrode having ^{a mixture layer density of 1.6 g / cm 3.}

(Example 4α-1)
(Making a secondary battery)
Using the negative electrodes and positive electrodes shown in Tables 5 and 6, punching into 50 mm × 45 mm and 45 mm × 40 mm, respectively, and inserting a separator (porous polyproprene film) inserted between them into an aluminum laminated bag, and making electricity. It was dried in an oven at 70 ° C. for 1 hour. Then, in a glove box filled with argon gas, an electrolytic solution (a mixed solvent in which ethylene carbonate, dimethyl carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1: 1 was prepared, and further, vinylene carbonate was prepared as an additive. After adding 1 part by mass to 100 parts by mass, _{injecting 2 mL of a non-aqueous electrolyte solution in which LiPF 6} was dissolved at a concentration of 1 M), the aluminum laminate was sealed, and the batteries for negative electrode evaluation 1 to 1 respectively. 30, negative electrode evaluation comparative batteries 1 to 6, positive electrode evaluation batteries 1 to 30, and positive electrode evaluation comparative batteries 1 to 6 were produced.

(Method of evaluating the rate characteristics of the secondary battery)
The obtained secondary battery was installed in a constant temperature room at 25 ° C., and charge / discharge measurement was performed using a charge / discharge device (manufactured by Hokuto Denko, SM-8). After performing constant current constant voltage charging (cutoff current 1mA (0.02C)) at a charging end voltage of 4.3V at a charging current of 10mA (0.2C), discharge at a discharge current of 10mA (0.2C). A constant current discharge was performed at a cutoff voltage of 3 V. After repeating this operation three times, constant current constant voltage charging (cutoff current (1mA 0.02C)) is performed at a charging end voltage of 4.3V with a charging current of 10mA (0.2C), and a discharge current of 0.2C and Constant current discharge was performed at 3C until the discharge cutoff voltage reached 3.0 V, and the discharge capacity was determined for each. The rate characteristic can be expressed by the following formula 1 which is the ratio of 0.2C discharge capacity and 3C discharge capacity.

(Formula 1) Rate characteristics = 3C discharge capacity / 3rd 0.2C discharge capacity x 100 (%)

Judgment criteria ◎: 80% or more (excellent)
◯: 60% or more and less than 80% (good)
×: Less than 60% (defective)

(Method of evaluating cycle characteristics of secondary battery)
The obtained secondary battery was installed in a constant temperature room at 25 ° C., and charge / discharge measurement was performed using a charge / discharge device (manufactured by Hokuto Denko, SM-8). After performing constant current constant voltage charging (cutoff current 2.5mA (0.05C)) at a charging end voltage of 4.3V at a charging current of 25mA (0.5C), a discharge current of 25mA (0.5C). , Constant current discharge was performed with a discharge cutoff voltage of 3 V. This operation was repeated 200 times. The cycle characteristics can be expressed by the ratio of the third 0.5C discharge capacity to the 200th 0.5C discharge capacity at 25 ° C., and the following formula 2.

(Formula 2) Cycle characteristics = 3rd 0.5C discharge capacity / 200th 0.5C discharge capacity x 100 (%)

Judgment criteria ◎: 85% or more (excellent)
◯: 80% or more and less than 85% (good)
×: Less than 80% (defective)

In the above embodiment using the dispersion of the present invention, an electrode having excellent conductivity and adhesion as compared with the comparative example, and a secondary battery having excellent rate characteristics and cycle characteristics were obtained. Therefore, it has been clarified that the present invention can provide a non-aqueous electrolyte secondary battery having excellent properties that cannot be realized by a conventional conductive material dispersion.

<Example β: Application to conductive paint>

(Preparation of conductive material dispersion)
(Example 1β-1)
According to the composition shown in Table 7, ion-exchanged water, a copolymer, a base and an antifoaming agent were added to a glass bottle, and the mixture was stirred with a disper until uniform. Then, a conductive material was added, 200 g of zirconia beads having a diameter of 0.5 mm was charged as a dispersion medium, and the dispersion treatment was carried out with a paint shaker for 6 hours to obtain a dispersion. A 10 mass% acetic acid aqueous solution and water were appropriately added to the obtained dispersion and stirred to obtain a conductive material dispersion (dispersion 1β) having a pH of 9.5 and a conductive material content of 0.3%.

(Examples 1β-2 to 1β-33, Comparative Examples 1β-1 to 1β-6)
According to the composition shown in Table 7, each dispersion (dispersion 2β to 33β, comparative dispersion 1β to 6β) was obtained in the same manner as in Example 1β-1. However, when the pH of the obtained dispersion was 9.5 or less, it was diluted with water only.

(Method of measuring pH during dispersion process)
The pH during the dispersion step was measured by adjusting the dispersion at 3 hours of the paint shaker to 25 ° C. using a pH meter.

(Stability evaluation method for conductive material dispersion)
The stability was evaluated by the change in viscosity of the conductive material dispersion. To measure the viscosity, use a B-type viscometer (“BL” manufactured by Toki Sangyo), stir the dispersion sufficiently with a spatula at a dispersion temperature of 25 ° C, and then set the rotor rotation speed of the B-type viscometer to 60 rpm. I went immediately. The rotor used for the measurement was No. 1 when the viscosity was less than 100 mPa · s. If 1 is 100 or more and less than 500 mPa · s, No. If 2 is 500 or more and less than 2,000 mPa · s, No. If 3 is 2,000 or more and less than 10,000 mPa · s, No. The ones of 4 were used respectively. The viscosity measured within 5 hours after the dispersion was taken as the initial viscosity, and the evaluation was made from the change in the viscosity value after the conductive material dispersion was allowed to stand at 50 ° C. for 10 days and stored. The rate of change was calculated by Eq. (2) and evaluated according to the following criteria based on the calculated results. The evaluation was made on a scale of 〇 (good), Δ (normal), and × (poor). Further, when the viscosity value is ">10", it is expressed as "-" (evaluation is not possible) because the calculation is impossible.
Rate of change (%) = (viscosity after 10 days at 50 ° C.) / (initial viscosity) x 100 ... Equation (2)
◯: Change rate is 80% or more and less than 120% Δ: Change rate is 50% or more and less than 80% or 120% or more and less than 150% ×: Change rate is less than 50% or 150% or more

(Particle size distribution of conductive material dispersion)
For the particle size distribution of the conductive material dispersion, a laser diffraction type particle size distribution (“Microtrack MT3000II” manufactured by Microtrac Bell) was used, and the volume ratio of the particles was integrated from the fine particle size distribution in the volume particle size distribution. The particle size was measured to be 50%, and a 50% particle size (D50) was obtained.

The abbreviations shown in Table 7 are the same as those in Table 2.

(Preparation of conductive paint and conductive film)
(Example 2β-1)
According to the composition shown in Table 8, a conductive material dispersion, a binder for paint, and water were added to the container, and the mixture was stirred with a disper until uniform to obtain paint 1.

(Examples 2β-2 to 37, Comparative Examples 2β-1 to 6)
Each paint (paints 2-37, comparative paints 1-6) was obtained in the same manner as in Example 2β-1 except that the dispersion was changed to the dispersion shown in Table 7.

(Paint evaluation)
With respect to the obtained paint, the paint was further applied to a corona discharge-treated PET film with a bar coater so that the film thickness was 2 μm, set for 30 minutes, dried at 60 ° C. for 30 minutes, and then heated to 140 ° C. After baking for 20 minutes, a test coating film for each paint was prepared, and the paint and its coating film were evaluated as follows. The results are shown in Table 3.
(Compatibility)
The compatibility of the obtained paint with the conductive material dispersion and the binder for paint was determined by confirming the density of particles according to JIS K56002-5. Evaluation was performed according to the following criteria. The evaluation was made on a two-point scale of 〇 (good) and × (poor).
◯: Dense less than 20 μm ×: Dense 20 μm or more (transparency)
Regarding the transparency, the total light transmittance of the test coating film applied to the PET film was measured with a haze meter (300A) manufactured by Nippon Denshoku Kogyo Co., Ltd. Evaluation was performed according to the following criteria. The evaluation was made on a scale of ⊚ (extremely good), 〇 (good), Δ (normal), and × (poor).
⊚: 80% or more and less than 90% 〇: 70% or more and less than 80% Δ: 60% or more and less than 70% ×: less than 60% (surface resistivity)
Regarding the conductivity, the surface resistivity (Ω / □) of the test coating film applied to the PET film was measured using Mitsubishi Chemical Corporation: Lorester GP (CP-T610). Evaluation was performed according to the following criteria. The evaluation was made on a scale of ⊚ (extremely good), 〇 (good), Δ (normal), and × (poor).
⊚: 1.0 × 10 ^{less than 8} 〇: 1.0 × 10 ⁸ or more and less than 1.0 × 10 ¹⁰ Δ: 1.0 × 10 ¹⁰ or more and 1.0 × 10 ^{less than 14} ×: 1.0 × 10 ¹⁴ or more (Not measurable)

The abbreviations shown in Table 8 mean the following.
-Urethane: Evafanol HA-107C (manufactured by NICCA CHEMICAL CO., LTD., Water-based urethane resin, solid content 40%)
-Olefin: Supercron E-415 (manufactured by Nippon Paper Industries, Ltd., water-based olefin resin, solid content 30%)

From the results shown in Tables 7 and 8, it was shown that the conductive material dispersion of the present invention was excellent in storage stability, compatibility with a binder for paints, and excellent transparency and surface resistivity.

The present invention is a conductive material dispersion containing a conductive material, a copolymer (A), a base (B), and water.
The conductive material contains single-walled carbon nanotubes having an average outer diameter of 1 to 4 nm.
The copolymer (A) contains 10% by mass to 99% by mass of units derived from (meth) acrylonitrile and 1% by mass to 90 % by mass of carboxyl group-containing monomer units, based on a total of 100% by mass of all units. It is a copolymer, and the base (B) has a pKb of 5 or less at 25 ° C. in water and a solubility of 1 g / 100 ml or more at 25 ° C. in water, and the copolymer (A) and the base (B). ) Shall have a solid content mass ratio (B) / (A) of 0.2 to 1.0.

Claims (15)

A conductive material dispersion containing a conductive material, a copolymer (A), a base (B), and water.
The conductive material contains single-walled carbon nanotubes having an average outer diameter of 1 to 4 nm.
The copolymer (A) contains 10% by mass to 99% by mass of units derived from (meth) acrylonitrile and 1% by mass to 50% by mass of carboxyl group-containing monomer units, based on a total of 100% by mass of all units. It is a copolymer, and the base (B) has a pKb of 5 or less at 25 ° C. in water and a solubility of 1 g / 100 ml or more at 25 ° C. in water, and the copolymer (A) and the base (B). ) Is a conductive material dispersion having a solid content mass ratio (B) / (A) of 0.2 to 1.0. The conductive material dispersion according to claim 1, wherein the copolymer (A) contains a carboxyl group-containing monomer unit in an amount of 11 to 40% by mass with respect to 100% by mass. The conductive material dispersion according to claim 1 or 2, wherein the pKb of the base (B) is 1 or less. The conductive material dispersion according to any one of claims 1 to 3, wherein the copolymer (A) contains acrylic acid and itaconic acid as a carboxyl group-containing monomer unit. The conductive material dispersion according to any one of claims 1 to 4, which comprises an acid. The conductive material dispersion according to any one of claims 1 to 5, wherein the copolymer (A) and the base (B) are contained in a total amount of 20% by mass to 1000% by mass with respect to the conductive material. The conductive material dispersion according to any one of claims 1 to 6, wherein the 50% particle size (D50) calculated by the laser diffraction type particle size distribution measurement is 1.5 to 40 μm. The conductive material dispersion according to any one of claims 1 to 7, wherein the pH is 8.0 to 13.0. The conductive material dispersion according to any one of claims 1 to 8, wherein the specific surface area of the conductive material is 400 to 800 m ^{2 / g.} A composition for a secondary battery electrode, comprising the conductive material dispersion according to any one of claims 1 to 9. An electrode film which is a coating film of the composition for a secondary battery electrode according to claim 10. A secondary battery comprising the electrode film according to claim 11. A conductive coating material comprising the conductive material dispersion according to any one of claims 1 to 9. A conductive coating film, which is a coating film of the conductive coating material according to claim 13. A method for producing a conductive dispersion containing a conductive material, a copolymer (A), a base (B), and water.
The conductive material contains single-walled carbon nanotubes having an average outer diameter of 1 to 4 nm.
The copolymer (A) is a copolymer containing a unit derived from (meth) acrylonitrile and a carboxyl group-containing monomer unit, and the base (B) has a pKb of 5 or less at 25 ° C. in water and is 5 or less. A step of dispersing the conductive material, the copolymer (A), the base (B), and water at a pH of 9.0 to 13.5, wherein the solubility in water at 25 ° C. is 1 g / 100 ml or more. A method for producing a conductive dispersion, which comprises a step of neutralizing the obtained dispersion.