JP2019061763A - Conductive paste for lithium ion battery positive electrode and mixture paste for lithium ion battery positive electrode - Google Patents

Abstract

To provide a mixture paste for a lithium ion battery positive electrode, which is suppressed an increase in viscosity and has a viscosity facilitating coating.SOLUTION: A conductive paste for a lithium ion battery positive electrode contains a dispersion resin (A), conductive carbon (B), a (meth)acryloyl group-containing compound (C), and a solvent (D), the content of the (meth)acryloyl group-containing compound (C) being 0.002-0.3 mass% based on 100 pts.mass of conductive carbon (B).SELECTED DRAWING: None

Description

  The present invention relates to a conductive paste for a lithium ion battery positive electrode and a mixture paste for a lithium ion battery positive electrode.

  The lithium ion secondary battery is a type of non-aqueous electrolyte secondary battery, and is a secondary battery in which lithium ions in the electrolyte perform electrical conduction. The lithium ion secondary battery has excellent characteristics such as high energy density, excellent retention characteristics of charging energy, and small so-called memory phenomenon in which the apparent capacity is reduced. Therefore, lithium ion secondary batteries are used in a wide range of fields such as mobile phones, smart phones, personal computers, hybrid cars, and electric cars.

  Here, the lithium ion secondary battery mainly includes a positive electrode plate, a negative electrode plate, a separator for insulating the positive electrode plate and the negative electrode plate, a non-aqueous electrolyte, and the like. The positive electrode plate has a positive electrode mixture layer formed on the surface of a positive electrode core material. The positive electrode mixture layer is formed by applying a positive electrode mixture material paste in which an electrode active material is mixed with a conductive paste containing a conductive auxiliary (carbon etc.), a binder and a solvent on the surface of a positive electrode core material and drying it. , Can be manufactured.

  As described above, since the production of the positive electrode mixture layer is performed by applying the positive electrode mixture paste on the surface of the positive electrode core material, the above-mentioned positive electrode mixture paste and the conductive paste which is the constituent material thereof have low viscosity It is required that Under such circumstances, methods of adding a dispersant for dispersing the conductive aid in the conductive paste or dispersion are known (Patent Documents 1 and 2). In addition, a method of using a specific vinyl alcohol polymer as a binder is also known (Patent Document 3).

  However, in the technical field to which the present invention belongs, development of a method for reducing the viscosity of the conductive paste and the positive electrode mixture paste is still eagerly desired.

JP, 2013-89485, A JP, 2014-193986, A Japanese Patent Application Laid-Open No. 11-250915

  The problem to be solved by the present invention is to provide a mixture paste for a lithium ion battery positive electrode, which has a viscosity that is easy to coat and can be easily increased.

  Under these circumstances, the inventors of the present invention conducted intensive studies and found that the conductive paste for lithium ion battery positive electrode containing the dispersion resin (A), the conductive carbon (B) and the solvent (D) contains a (meth) acryloyl group-containing compound (C) is added, and the content of the (meth) acryloyl group-containing compound (C) in the conductive paste for a lithium ion battery positive electrode is 0.001 to 0. parts based on 100 parts by mass of the conductive carbon (B). It has been found that the problem can be solved by setting the content to 3% by mass. The present invention is based on such novel findings.

Accordingly, the present invention provides the following items:
Item 1. It is a conductive paste for lithium ion battery positive electrodes containing dispersion resin (A), conductive carbon (B), (meth) acryloyl group containing compound (C), and solvent (D),
The content of the (meth) acryloyl group-containing compound (C) is 0.002 to 0.3% by mass based on 100 parts by mass of the conductive carbon (B). paste.
Item 2. The conductive paste for a lithium ion battery positive electrode according to item 1, further comprising polyvinylidene fluoride (E).
Item 3. Item 3. The conductive paste for lithium ion battery positive electrode according to Item 1 or 2, wherein the (meth) acryloyl group-containing compound (C) contains a (meth) acrylamide compound (C-1).
Item 4. The conductive paste for a lithium ion battery positive electrode according to Item 3, wherein the (meth) acrylamide compound (C-1) is a hydroxyl group-containing (meth) acrylamide compound (C-2).
Item 5. 5. The conductive paste for a lithium ion battery positive electrode according to any one of Items 1 to 4, wherein the molecular weight of the (meth) acryloyl group-containing compound (C) is 70 to 500.
Item 6. The mixed material paste for lithium ion battery positive electrodes formed by further mix | blending an electrode active material with the electrically conductive paste of any one of claim | item 1 -5.
Item 7. 7. An electrode for a lithium ion battery positive electrode obtained using the mixture paste for lithium ion battery positive electrode according to item 6.
Item 8. Item 8. A lithium ion battery having the lithium ion battery positive electrode according to Item 7.

  The conductive paste for a lithium ion battery positive electrode and the mixture paste for a lithium ion battery positive electrode according to the present invention have a higher viscosity than the conventional conductive or positive electrode paste for a lithium ion battery positive electrode due to the features of the configuration. It is suitable for coating. Although the reason why the increase in viscosity of the conductive paste for lithium ion battery positive electrode of the present invention and the composite material paste for lithium ion battery positive electrode is suppressed is not clear, the hydrogen bond strength (can be measured by Hansen solubility parameter) is relatively high. It is speculated that the presence of the low molecular weight compound improves the affinity to the conductive carbon and the active material, and the viscosity can be reduced. (However, if a large amount of low molecular weight compounds are contained, the storage properties of the paste may be deteriorated.)

Hereinafter, modes for carrying out the present invention will be described in detail.
The present invention is not limited to the following embodiments, and should be understood as including various modifications implemented within the scope of the present invention.

  Also, in the present specification, “(meth) acrylate” means acrylate and / or methacrylate, and “(meth) acrylic acid” means acrylic acid and / or methacrylic acid. Also, "(meth) acryloyl" means acryloyl and / or methacryloyl. Also, "(meth) acrylamide" means acrylamide and / or methacrylamide. Further, “polymerizable unsaturated monomer” means a monomer having a polymerizable unsaturated group capable of radical polymerization, and as the polymerizable unsaturated group, for example, (meth) acryloyl group, acrylamide group, vinyl group And allyl groups, (meth) acryloyloxy groups, vinyl ether groups and the like. Further, in the present specification, the term "pigment" is described as a concept including conductive carbon, an electrode active material, and the like.

Conductive paste for lithium ion battery positive electrode The present invention is a conductive paste for lithium ion battery positive electrode containing dispersion resin (A), conductive carbon (B), (meth) acryloyl group-containing compound (C), and solvent (D) There,
The content of the (meth) acryloyl group-containing compound (C) is 0.002 to 0.3% by mass based on 100 parts by mass of the conductive carbon (B). Provide a paste.

  In the conductive paste for lithium ion battery positive electrode according to the present invention, the content of the (meth) acryloyl group-containing compound (C) is 0.002 to 0.3 mass% based on 100 parts by mass of the conductive carbon (B) It is characterized in that 0.006 to 0.1% by mass is preferable, and 0.01 to 0.07% by mass is more preferable.

  In the present invention, the (meth) acryloyl group-containing compound (C) is not particularly limited as long as it is a compound having a (meth) acryloyl group, but a low molecular weight compound is preferable, and more specifically, for example, the molecular weight is 70-500 are preferable and 80-450 are more preferable.

  In a preferred embodiment of the present invention, examples of the (meth) acryloyl group-containing compound (C) include a (meth) acrylamide compound (C-1) and the like. Therefore, in the present invention, the content of the (meth) acrylamide compound (C-1) is preferably 0.002 to 0.3% by mass, based on 100 parts by mass of the conductive carbon (B). 00 to 0.1% by mass is more preferable, and 0.01 to 0.07% by mass is more preferable.

  As the (meth) acrylamide compound, those known per se can be used without particular limitation, and specifically, for example, acrylamide, methacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamidobutyl ether, N-methylol methacrylamido butyl ether, N-ethyl acrylamide, N-ethyl methacrylamide, N-n-propyl acrylamide, N-n-propyl methacrylamide, N-isopropyl acrylamide, N-isopropyl methacrylamide, N-cyclopropyl acrylamide, N-cyclopropyl methacrylamide, diacetone acrylamide, diacetone methacrylamide, N-hydroxy methacrylate Acrylamide, N-hydroxymethyl methacrylamide, N-hydroxyethyl acrylamide, N-hydroxypropyl acrylamide, N-hydroxybutyl acrylamide, N-hydroxypentyl acrylamide, N-hydroxymethyl-N-ethyl acrylamide, N-methyl-N- Hydroxyethyl acrylamide, N, N-dihydroxymethyl acrylamide, N, N-dihydroxyethyl acrylamide, N, N-dihydroxypropyl acrylamide, N, N-dihydroxybutyl acrylamide, N, N-dihydroxypentyl acrylamide, N-hydroxymethyl methacrylamide N-hydroxyethyl methacrylamide, N-hydroxy propyl methacrylamide, N-hydroxy butyl methacrylamide N-hydroxypentyl methacrylamide, N-hydroxymethyl-N-ethyl methacrylamide, N-methyl-N-hydroxyethyl methacrylamide, N, N-dihydroxymethyl methacrylamide, N, N-dihydroxyethyl methacrylamide, N, N-Dihydroxypropyl methacrylamide, N, N-dihydroxybutyl methacrylamide, N, N-dihydroxypentyl methacrylamide, N, N-dihydroxybutyl (meth) acrylamide, and N- [tris (hydroxymethyl) methyl) acrylamide, N , N-dimethyl acrylamide, N, N- dimethyl methacrylamide, N, N- diethyl acrylamide, N, N- diethyl methacrylamide, N- methyl, N- ethyl acrylamide, N- methyl, N- eth N-methylol acrylamido methyl ether, N-methylol methacrylamido methyl ether, N-methylol acrylamido ethyl ether, N-methylol methacrylamide ethyl ether, N-methylol acrylamidopropyl ether, N-methylol methacrylamidopropyl ether, N -Methylol acrylamido butyl ether, N-methylol methacrylamido butyl ether, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N -Amino group-containing (meth) acrylamide compounds such as dipropylaminoethyl (meth) acrylamide, methacryloyloxyethyl Trimethyl ammonium chloride (ACRYESTER DMC, tradename, manufactured by Mitsubishi Rayon Co., Ltd.) Quaternary ammonium salt group-containing acrylamide compounds such as, can be exemplified acryloyl morpholine. These can be used singly or in combination of two or more.

Among them, (meth) acrylamide compounds represented by the following formula are preferable.
_{CH 2 = C (-R 1)} -C (= O) -N (-R 2) -R 3
R ₁ in the above formula is a hydrogen atom or a methyl group, and R ₂ and R ₃ may be different or the same and at least one selected from a hydrogen atom, an organic group having a hydroxyl group and an alkyl group preferable. Furthermore, it is more preferable that both or one of R ₂ and R ₃ is an organic group having a hydroxyl group, and specifically, for example, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N- Hydroxypropyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide, N-hydroxymethyl-N-ethyl (meth) acrylamide, N-methyl-N-hydroxyethyl (meth) acrylamide, N-ethyl-N-hydroxyethyl (Meth) acrylamide, N-hydroxyethyl-N-butyl (meth) acrylamide, N-hydroxybutyl-N-butyl (meth) acrylamide, N, N-dihydroxymethyl (meth) acrylamide, N, N-dihydroxyethyl (meth) ) Acrylamide, N, N Dihydroxypropyl (meth) acrylamide, N, and particularly preferably at least one selected from N- dihydroxy-butyl (meth) acrylamide, and N- [tris (hydroxymethyl) methyl) acrylamide.

  Moreover, as a (meth) acrylamide compound (C-1) in this invention, a hydroxyl-containing (meth) acrylamide compound (C-2) etc. are preferable. As a hydroxyl-containing (meth) acrylamide compound (C-2), the thing containing a hydroxyl group etc. are mentioned among the compounds mentioned above, for example.

  The total solid content of the dispersion resin (A) in the solid content of the conductive paste for lithium ion battery positive electrode of the present invention is usually 30% by mass or less, preferably 20% by mass or less, at the time of pigment dispersion It is suitable from the aspects of viscosity, pigment dispersibility, dispersion stability and production efficiency. In addition, the total amount of the solid content of the dispersion resin (A) in the solid content of the conductive paste for lithium ion battery positive electrode of the present invention is usually 0.1 mass% or more, preferably 1 mass% or more. It is.

  The solid content of the conductive carbon (B) in the solid content of the conductive paste for lithium ion battery positive electrode of the present invention is usually 30% by mass or more and less than 97% by mass, preferably 50% by mass or more and 94% by mass Less than 70% by mass, and more preferably less than 91% by mass is preferable in terms of battery performance. The content of the solvent (C) in the conductive paste for lithium ion battery positive electrode of the present invention is usually 30% by mass or more and less than 95% by mass, preferably 45% by mass or more and less than 92% by mass Preferably, 60% by mass or more and less than 90% by mass are suitable from the viewpoint of drying efficiency and paste viscosity.

Dispersion resin (A)
As the dispersion resin (A), resins used in the field of batteries to which the present invention belongs can be appropriately used. As a dispersion resin (A), resin (A1) which has a polycyclic aromatic hydrocarbon group, polyvinyl alcohol resin (A2) etc. are mentioned, for example. In the present invention, the dispersion resin (A) preferably contains both a resin (A1) having a polycyclic aromatic hydrocarbon group and a polyvinyl alcohol resin (A2).

Resin having polycyclic aromatic hydrocarbon group (A1)
The resin (A1) having a polycyclic aromatic hydrocarbon group is, for example, 1 to 70% by mass of a monomer (A1-1) having a polycyclic aromatic hydrocarbon, based on the total amount of solid components of the monomer mixture. It can be obtained by copolymerizing the monomer mixture contained. The resin (A1) in this case is rephrased as a copolymer of a monomer mixture containing 1 to 70% by mass of the monomer (A1-1) having a polycyclic aromatic hydrocarbon based on the total amount of solid components of the monomer mixture. It can also be done. Moreover, resin which has a polycyclic aromatic hydrocarbon group can also be obtained by adding polycyclic aromatic hydrocarbon, after synthesize | combining resin which does not have polycyclic aromatic hydrocarbon.

  As a kind of said resin (A1), an acrylic resin, a polyester resin, an epoxy resin, a polyether resin, an alkyd resin, a urethane resin, a silicone resin, a polycarbonate resin, a silicate resin, a chlorine resin, a fluorine resin, and these are mentioned, for example. And the like, and acrylic resins are particularly preferable.

  In the present specification, “derivative” is obtained by changing a small part (or a plurality of parts) in a molecule by introducing a functional group, substituting an atom, or other chemical reaction to a certain compound. Means a compound that For example, to naphthalene, one or more functional groups such as an alkyl group, an alkoxy group, a hydroxyl group, a sulfonic acid group, a carboxyl group, an amino group, a nitro group, a halogen atom, an aryloxy group, an alkylthio group, an arylthio group, etc. The introduced compound is a naphthalene derivative.

Monomer having polycyclic aromatic hydrocarbon (A1-1)
Examples of the polycyclic aromatic hydrocarbon of the monomer (A1-1) having the above-mentioned polycyclic aromatic hydrocarbon include naphthalene ring, anthracene ring, triphenylene ring, tetraphen ring, tetracene ring, chrysene ring, pyrene ring, pentacene Examples thereof include hydrocarbon groups having a ring, a hexacene ring, a heptacene ring, a coronene ring, and a keklen ring and derivatives thereof. In a preferred embodiment of the present invention, as the monomer (A1-1) having a polycyclic aromatic hydrocarbon, among the above polycyclic aromatics, one having a naphthalene ring, that is, a polymerizable unsaturated monomer having a naphthyl group Or its derivative (A1-2). As a polymerizable unsaturated monomer which has a naphthyl group, or its derivative (A1-2), the polymerizable unsaturated monomer which has a naphthyl group represented by Formula (3) mentioned later, or its derivative (A1-1-2) is mentioned, for example Etc.

  Moreover, it is a polymerizable unsaturated monomer (A1-1-1) which has the polycyclic aromatic hydrocarbon represented by following formula (2) as a monomer (A1-1) which has the said polycyclic aromatic hydrocarbon Is preferred.

(Wherein R represents a hydrogen atom or a methyl group, A represents a polycyclic aromatic hydrocarbon group, and W may or may not be present. When W is present, W is a carbon atom, The number of nitrogen atoms and / or oxygen atoms is an organic group having 1 to 20, and when W is absent, W is directly bonded to A. The "polymerizable unsaturated monomer" is a radically polymerizable polymerization A monomer having a heterocyclic unsaturated group, and examples of the polymerizable unsaturated group include (meth) acryloyl group, acrylamide group, vinyl group, allyl group, (meth) acryloyloxy group, vinyl ether group and the like .

  Specific examples of the polymerizable unsaturated monomer (A1-1-1) having the polycyclic aromatic hydrocarbon include vinyl naphthalene, naphthyl (meth) acrylate, naphthyl alkyl (meth) acrylate, vinyl anthracene, and the like. Anthracenyl (meth) acrylate, anthracenyl alkyl (meth) acrylate, vinyl pyrene, pyrenyl (meth) acrylate, pyrenyl alkyl (meth) acrylate, vinyl chrysene, vinyl naphthacene, vinyl pentacene, and derivatives thereof, and the like can be mentioned. Also, those obtained by reacting a polymerizable unsaturated group monomer having a reactive functional group such as a glycidyl group or an isocyanate group with a polycyclic aromatic hydrocarbon having a functional group capable of reacting with the reactive functional group are included. . Any combination of functional groups that react with each other can be suitably used, but a combination of a carboxyl group and a glycidyl group, an amino group and a glycidyl group, and a hydroxyl group and an isocyanate group is more preferable. Specifically, for example, glycidyl (meth) acrylate and 1-naphthylacetic acid, 2- (meth) acryloyloxyethyl isocyanate and 1-naphthol, 2- (meth) acryloyloxyethyl isocyanate and 1- (2-naphthyl) ethanol Combinations of These can be used singly or in combination of two or more.

  Among them, as the polymerizable unsaturated monomer (A1-1-1) having a polycyclic aromatic hydrocarbon, a polymerizable unsaturated monomer having a naphthyl group represented by the following formula (3) or a derivative thereof (A1-1 -2) is preferable.

(Wherein R represents a hydrogen atom or a methyl group, and X and Y may be the same or different, and a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyloxy group, a phosphoryloxy group, a hydroxyl group, a sulfone Group represents any of an acid group, a carboxyl group, an amino group, a nitro group, a halogen atom, an aryloxy group, an alkylthio group or an arylthio group, and when W is present, W is the number of carbon atoms, nitrogen atoms and / or oxygen atoms Is an organic group of 1 to 20 or a single bond.)

  As a polymerizable unsaturated monomer which has the said naphthyl group, or its derivative (A1-1-2), vinyl naphthalene, a naphthyl (meth) acrylate, a naphthyl alkyl (meth) acrylate, these derivatives, etc. are mentioned, for example. These can be used singly or in combination of two or more.

  Especially, it is preferable that a naphthyl (meth) acrylate or its derivative (A1-1-2) is a naphthyl (meth) acrylate or its derivative (A1-1-3) represented by following formula (4).

(Wherein R represents a hydrogen atom or a methyl group, and X and Y may be the same or different, and a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, a sulfonic acid group, a carboxyl group, an alkoxycarbonyloxy Group represents a phosphoryloxy group, an amino group, a nitro group, a halogen atom, an aryloxy group, an alkylthio group or an arylthio group).

  As said naphthyl (meth) acrylate or its derivative (A1-1-3), 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, these derivatives etc. are mentioned, for example, These are 1 type Can be used alone or in combination of two or more.

  Among them, naphthyl (meth) acrylate or its derivative (A1-1-3) is 4-substituted-1-naphthyl (meth) acrylate (A1-1-4) represented by the following formula (5) preferable.

(In the formula, R represents a hydrogen atom or a methyl group, and Z represents a hydroxyl group or an alkoxy group having 1 to 8 carbon atoms.)

  When Z which is a substituent in the above formula (5) is an alkoxy group, the carbon number of the alkoxy group is usually 1 to 8, preferably 1 to 4, more preferably 1 to 2, Particularly preferably, it is 1.

  Examples of the 4-substituted-1-naphthyl (meth) acrylate (A1-1-4) include 4-methyl-1-naphthyl (meth) acrylate, 4-ethyl-1-naphthyl (meth) acrylate, and Methoxy-1-naphthyl (meth) acrylate, 4-ethoxy-1-naphthyl (meth) acrylate, 4-hydroxy-1-naphthyl (meth) acrylate, 2-methoxy-4-hydroxy-1-naphthyl (meth) acrylate, 2-ethoxy-4-hydroxy-1-naphthyl (meth) acrylate, 2-hydroxy-4-methoxy-1-naphthyl (meth) acrylate, 2-hydroxy-4-ethoxy-1-naphthyl (meth) acrylate, 4- Methoxycarbonyloxy-1-naphthyl (meth) acrylate, 4-phenoxycarbonyl oxide -1-Naphthyl (meth) acrylate, 4-phosphoryloxy 1-naphthyl (meth) acrylate, or a derivative thereof, and the like, and these can be used singly or in combination of two or more. .

  The reason why the pigment dispersion resin having polycyclic aromatic hydrocarbon of the present invention is effective for the dispersibility and stability of the pigment is not known in detail, but, for example, the pigment has an aromatic ring In this case, it is considered that the pigment is stabilized by π-π interaction between the pigment and the pigment dispersion resin. In addition, (pi)-(pi) interaction is dispersion force which works between aromatic rings, and since it tends to be stabilized by arrangement | positioning which two aromatic rings pile up coin, it is also called stacking interaction.

  Moreover, although it is not understood in detail as a reason that the substituent of the said 4-substituted 1-naphthyl (meth) acrylate (A1-1-4) is effective in the dispersibility and stability of a pigment, for example, By having a substituent, it is speculated that the electrostatic potential of the aromatic ring is increased to enhance the affinity to the pigment.

Polymerizable unsaturated monomer other than polymerizable unsaturated monomer (A1-1) having polycyclic aromatic hydrocarbon The resin (A1) having the above-mentioned polycyclic aromatic hydrocarbon group is a polymerization having polycyclic aromatic hydrocarbon It can be obtained by copolymerizing a polymerizable unsaturated monomer (A1-1) and a polymerizable unsaturated monomer other than the (A1-1). As the polymerizable unsaturated monomer other than the polymerizable unsaturated monomer (A1-1) having a polycyclic aromatic hydrocarbon, any polymerizable unsaturated monomer generally used in the synthesis of an acrylic resin is used without particular limitation. For example, alkyl (meth) acrylate having 3 or less carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) Acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl Meta) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, t-butyl cyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate, etc. Alkyl or cycloalkyl (meth) acrylate; polymerizable unsaturated compound having isobornyl group such as isobornyl (meth) acrylate; polymerizable unsaturated compound having an adamantyl group such as adamantyl (meth) acrylate; benzyl (meth) acrylate, styrene And aromatic ring-containing polymerizable unsaturated monomers such as α-methylstyrene and vinyltoluene; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydric acid Monoesters of (meth) acrylic acid and a C2-C8 dihydric alcohol such as roxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; the (meth) acrylic acid and the C2-8 carbon Hydroxylated polymers such as ε-caprolactone modified products of monoesters with dihydric alcohols, N-hydroxymethyl (meth) acrylamide, allyl alcohol, and (meth) acrylates having a polyoxyalkylene chain whose molecular terminal is a hydroxyl group Unsaturated monomers; carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl ( (Meth) acrylate, N, N-diethylaminoethyl ( Nitrogen-containing polymerizable unsaturated monomers containing no urethane bond such as an adduct of (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, glycidyl (meth) acrylate and an amine compound; isocyanate group-containing polymerizable unsaturated Polymerizable unsaturated monomers having a urethane bond such as reaction products of monomers and hydroxyl group-containing compounds or reaction products of hydroxyl group-containing polymerizable unsaturated monomers and isocyanate group-containing compounds; glycidyl (meth) acrylate, β-methyl glycidyl (Meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, epoxy group-containing allyl glycidyl ether, etc. Polymerizable unsaturated monomer; (meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group; 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrene Polymerizable unsaturated monomers having a sulfonic acid group such as sulfonic acid, sodium salt and ammonium salt of these sulfonic acids; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, Polymerizable unsaturated monomers having a phosphoric acid group such as 2-methacryloyloxypropyl acid phosphate; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) sila Polymerizable unsaturated monomers having an alkoxysilyl group such as gamma, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, etc .; perfluorobutylethyl (meth) acrylate, perfluorooctyl Perfluoroalkyl (meth) acrylates such as ethyl (meth) acrylate; polymerizable unsaturated monomers having a fluorinated alkyl group such as fluoroolefins; polymerizable unsaturated monomers having a photopolymerizable functional group such as a maleimide group; molecular terminal (Meth) acrylate having a polyoxyethylene chain in which is an alkoxy group; allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) a Crylates, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol Di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethane di (meth) acrylate, 1,1,1 -Polymerizable unsaturated groups such as trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene, etc. Polymerizable unsaturated monomers having two or more in the child and the like. These can be used singly or in combination of two or more.

  Among them, it is preferable to contain at least one type of styrene, and it is more preferable to contain 5 to 65% by mass of styrene based on the total amount of the polymerizable unsaturated monomer component.

  In addition, from the viewpoint of forming a steric repulsion layer of a resin to ensure the stability of the pigment dispersion paste, a polyalkylene glycol macromonomer can be contained based on the total amount of the polymerizable unsaturated monomer component.

The polyalkylene glycol macromonomer is a nonionic polymerizable unsaturated monomer represented by the following formula (6), and specific examples of such a monomer include, for example, polyethylene glycol (meth) acrylate and polypropylene glycol Examples include (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate and the like. Among these, polyethylene glycol (meth) acrylate and polypropylene glycol (meth) acrylate are particularly preferable.
_{CH 2 = C (R 1)} COO (C n H 2n O) m -R 2 ··· formula (6)
[Wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m is an integer of 4 to 60, particularly 4 to 55, and n is 2] It is an integer of ̃3, and the m oxyalkylene units (C _n H _{2 n} O) may be the same or different from one another. ]

Synthesis of Resin (A1) Having Polycyclic Aromatic Hydrocarbon Group The method of solution polymerization in an organic solvent in the presence of a radical polymerization initiator, or the resin (A1) having a polycyclic aromatic hydrocarbon group, or It can be obtained by a radical polymerization method known per se, such as a method of emulsion polymerization in an aqueous medium.

  As a radical polymerization initiator used for polymerization, for example, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-bis (tert-butylperoxy) -3,3, 5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, cumene hydroperoxide, 2,5-dimethylhexane-2 5-Dihydroperoxide, 1,3-bis (tert-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, diisopropylbenzene peroxide , Tert-Butylcumyl peroxide, Decanoylpa Oxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-tert-amyl peroxide, bis (tert-butylcyclohexyl) peroxydicarbonate, tert-butylperoxybenzoate, 2,5- Peroxide type polymerization initiators such as dimethyl-2,5-di (benzoylperoxy) hexane and tert-butylperoxy-2-ethylhexanoate; 2,2'-azobis (isobutyronitrile), 1 1,2-azobis (cyclohexane-1-carbonitrile), azocumene, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobisdimethylvaleronitrile, 4,4′-azobis (4- Cyanovaleric acid), 2- (t-butylazo) -2-cyanopropane, 2,2′-azobis ( Azo polymerization initiators such as 2,4,4-trimethylpentane), 2,2'-azobis (2-methylpropane), dimethyl 2,2'-azobis (2-methylpropionate) and the like can be mentioned . These can be used singly or in combination of two or more.

  There is no restriction | limiting in particular as a solvent used for said superposition | polymerization or dilution, Water, an organic solvent, or its mixture etc. can be mentioned. Examples of the organic solvent include hydrocarbon solvents such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane and cyclobutane; aromatic solvents such as toluene and xylene; methyl isobutyl ketone and the like Ketone solvents; ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol; ethyl acetate, n-butyl acetate, isobutyl acetate, Ester solvents such as ethylene glycol monomethyl ether acetate and butyl carbitol acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; Alcohol solvents such as alcohol, isopropanol, n-butanol, sec-butanol, isobutanol, etc .; Equamide (trade name, manufactured by Idemitsu Kosan Co., Ltd., amide solvent), N, N-dimethylformamide, N, N- Known solvents such as amide solvents such as dimethylacetamide, N-methylformamide, N-methylacetamide, N-methylpropioamide, N-methyl-2-pyrrolidone and the like can be mentioned. These can be used singly or in combination of two or more.

  Method of mixing a polymerization initiator, a polymerizable unsaturated monomer component, and an organic solvent in solution polymerization in an organic solvent and heating while stirring, an organic solvent in a reaction tank to suppress the temperature rise of the system due to the heat of reaction Charge, while stirring at a temperature of 60 ° C. to 200 ° C. As necessary, while blowing in an inert gas such as nitrogen or argon, the polymerizable unsaturated monomer component and the polymerization initiator are mixed dropwise or separated dropwise over a predetermined time Methods etc. are used.

  The polymerization can generally be carried out for about 1 to 10 hours. After the polymerization of each step, an additional catalyst step may be provided to heat the reaction vessel while dropping a polymerization initiator as needed.

  The pigment dispersion resin of the present invention obtained as described above preferably has a weight average molecular weight of preferably 1,000 to 100,000, more preferably 3,000 to 50,000.

  The resin (A1) can be converted into a solid or a resin solution replaced with an arbitrary solvent by desolvation and / or solvent substitution after the completion of synthesis. As the substitution solvent, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, propylene glycol monomethyl ether, alcohol solvents and the like are preferable.

  The solvent may be removed by heating at normal pressure or may be removed under reduced pressure. As a method of solvent substitution, the substitution solvent may be introduced at any stage before solvent removal, during solvent removal, or after solvent removal.

  In the present specification, the number average molecular weight and the weight average molecular weight are the retention times of standard polystyrenes of known molecular weight whose retention time (retention volume) measured using gel permeation chromatography (GPC) was measured under the same conditions. (Retention capacity) is a value determined by converting into molecular weight of polystyrene. Specifically, “HLC 8120 GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” as a column And using “TSKgel G-2000HXL” (trade name, all manufactured by Tosoh Corporation), under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min and detector RI it can.

Polyvinyl alcohol resin (A2)
As the polyvinyl alcohol resin (A2), a resin obtained by copolymerizing a polymerizable unsaturated group-containing monomer (A2a-1) represented by the following formula (1) with another polymerizable unsaturated monomer (this specification In the examples, it may be simply referred to as polyvinyl alcohol resin (A2a) or resin (A2a), sulfonic acid-modified polyvinyl alcohol resin (A2b) (herein, simply referred to as polyvinyl alcohol resin (A2b) or resin (A2b) And polyvinyl alcohol resin (A2c) other than resin (A2a) and resin (A2b) (sometimes referred to herein as polyvinyl alcohol resin (A2c) or resin (A2c)). Will be:

(Wherein, R ₁ , R ₂ , R ₃ and R ₄ are the same or different and at least one selected from the group consisting of a hydrogen atom, a hydrocarbon group, a hydroxyl group and a methylol group, and R ₁ and R 4 _At least one of R ₂ , R ₃ and R ₄ is a hydroxyl group, X may or may not be present, and when X is present, X is a linking chain consisting of one or more atoms. ).

  In the present invention, polyvinyl alcohol resin (A2a) and / or polyvinyl alcohol resin (A2b) can be suitably used as polyvinyl alcohol resin (A2), but polyvinyl alcohol resin (A2c) may be used in combination. Is preferred.

Polyvinyl alcohol resin (A2a)
A polyvinyl alcohol resin (A2a) is a resin obtained by copolymerizing the polymerizable unsaturated group containing monomer (A2a-1) shown by said Formula (1), and another polymerizable unsaturated monomer. In the present invention, “a resin having the polymerizable unsaturated group-containing monomer (A2a-1) as one of the constituent components” means (co) polymerization of a raw material monomer containing the polymerizable unsaturated group-containing monomer (A2a-1) Mean the resin obtained by Similarly, in the present invention, a resin that “consists of monomer X” means a resin obtained by (co) polymerizing a raw material containing monomer X. Further, the polyvinyl alcohol resin (A2a) is not subjected to sulfonic acid modification, and can be clearly distinguished from the sulfonic acid-modified polyvinyl alcohol resin (A2b).

R ₁ , R ₂ , R ₃ and R ₄ in the polymerizable unsaturated group-containing monomer (A2a-1) represented by the above formula (1) are the same or different, and a hydrogen atom, a hydrocarbon group, a hydroxyl group, a methylol At least one selected from groups, and at least one of R ₁ , R ₂ , R ₃ and R ₄ (for example, 1 to 3 are preferable, and 2 to 3 are more preferable) is a hydroxyl group. Furthermore, X in the monomer represented by the above formula (1) may or may not be present, and is a single bond when it is absent, and a linkage consisting of one or more atoms when X is present It is a chain. Such a linking chain is not particularly limited, and is, for example, alkylene (for example, linear or branched alkylene having 1 to 6 carbon atoms) or alkenylene (for example, linear or branched having 2 to 6 carbon atoms) , An alkenylene having one or two double bonds (preferably one), an alkynylene (for example, a straight or branched chain having 2 to 6 carbon atoms, and one or two triple bonds (preferably) 1) Alkynylenes), hydrocarbon groups such as phenylene and naphthylene (these hydrocarbon groups may be substituted with halogens such as fluorine, chlorine, bromine and the like), -O-,-(R- O) _m -,-(O-R) _m -,-(R-O) _m -R-, -C (= O)-, -R (-OH)-, -C (= O) -O- , -RC (= O) -O-, -C (= O) -O-R-, -C (= O) -N (-R)-, -C = O) -N (-R) -R-, -RC (= O) -N (-R)-, -RC (= O) -N (-R) -R-, etc. Be (The above R is each independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group. M is an integer of 1 or more.)
Among them, a single bond (X does not exist), a hydrocarbon group, an ester group [-C (= O) -O-], an amido group [-C (= O) -NH-], an amidomethyl group [-C (= It is preferable that it is a connection chain chosen from O) NH-CH2-, and it is more preferable that it is a single bond (X is absent).

  As such a monomer (A2a-1), specifically, for example, hydroxyethyl (meth) acrylate, a ring-opened product of glycidyl (meth) acrylate, 2-propen-1-ol, 1-propene-1,3-diol , 1-propen-2-ol, 2-methyl-2-propen-1-ol, 2-buten-1-ol, 2-methyl-2-buten-1-ol, 1-methyl-2-buten-1-ol , 2-butene-1,4-diol, 1-butene-3,4-diol, 2-methyl-2-butene-1,4-diol, 4-penten-2-ol, 3-pentene-1- 1 -Ol, 4-penten-2-ol, 4-penten-1-ol, 1-pentene-4,5-diol, 2-pentene-1,5-diol, N-hydroxymethyl (meth) acrylamide N-hydroxyethyl (meth) acrylamide, N-hydroxyisopropyl (meth) acrylamide, N- (1-methyl-2-hydroxyethyl) (meth) acrylamide, 2,3-dihydroxypropyl (meth) acrylamide, 1,2- Dihydroxyethyl (meth) acrylamide, its derivative, etc. are mentioned.

  These can be used singly or in combination of two or more. Among them, those having two or more hydroxyl groups are preferable.

The total number of carbon atoms and oxygen atoms in X, R ₃ and R ₄ in the monomer (A2a-1) represented by the formula (1) is preferably 3 or more.

  The content ratio of the polymerizable unsaturated group-containing monomer (A2a-1) in the resin (A2a) is preferably in the range of 0.01 to 20% by mass, and in the range of 0.1 to 15% by mass It is more preferable that it is, and it is especially preferable that it is in the range of 0.5-10 mass%. In the present invention, “the content ratio of the polymerizable unsaturated group-containing monomer (A2a-1) in the resin (A2a)” means a polymerizable unsaturated group-containing monomer in the monomer mixture which is a raw material of the resin (A2a) It means the content ratio of A2a-1). Therefore, the content ratio of the polymerizable unsaturated group-containing monomer (A2a-1) in the resin (A2a) is 0.1 to 20% by mass means that the resin (A2a) is a polymerizable unsaturated group-containing monomer It means that it is a copolymer of the raw material monomer which contains 0.1-20 mass% of (A2a-1). Similarly, the “content ratio of the monomer X in the resin Y” means the content ratio of the monomer X in the monomer mixture that is the raw material of the resin Y. Therefore, that the content ratio of the polymerizable unsaturated group-containing monomer X in the resin Y is a mass% means that the resin Y is a copolymer of a raw material monomer containing a mass% of the monomer X. .

  As other polymerizable unsaturated monomers copolymerizable with the above-mentioned polymerizable unsaturated group-containing monomer (A2a-1), any monomers copolymerizable with the monomer (A2a-1) can be used without particular limitation. Specifically, for example, fatty acid vinyl esters such as vinyl acetate; olefin monomers such as ethylene and propylene; (meth) acryloyl group-containing monomers such as alkyl (meth) acrylate; allyl ethers such as allyl glycidyl ether; Examples thereof include halogenated vinyl compounds such as vinyl chloride, vinylidene chloride and vinyl fluoride; and vinyl ethers such as alkyl vinyl ethers. These can be used singly or in combination of two or more. Among them, fatty acid vinyl esters (A2a-2) are preferable. Specific examples of the fatty acid vinyl ester (A2a-2) include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl caprylate, vinyl caproate, vinyl laurate and vinyl myristate. And vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate, vinyl monochlorate, vinyl benzoate, vinyl cinnamate, vinyl crotonate, vinyl adipate, and derivatives thereof, with vinyl acetate being preferred. .

  Further, by saponifying the resin (A2a) obtained by copolymerization, it is preferable to hydrolyze all or part of the fatty acid vinyl ester unit to form a vinyl alcohol unit from the viewpoint of dispersibility and solubility.

The degree of saponification is preferably in the range of 50 to 100 mol%, more preferably in the range of 70 to 100 mol%, still more preferably in the range of 86 to 100 mol%, and 88 to 99 It is particularly preferable to be in the range of 9 mol%.
In other words, the resin (A2a) is polymerized by saponifying a copolymer of at least one polymerizable unsaturated group-containing monomer (A2a-1) and at least one fatty acid vinyl ester (A2a-2). It is particularly preferable that the resin is a resin having the unsaturated unsaturated group-containing monomer (A2a-1), the fatty acid vinyl ester (A2a-2), and the vinyl alcohol (A2a-3) as constituent components.

  Usually, when the degree of saponification (high polarity) is high, the adsorptivity to inorganic pigments such as carbon is improved, but the solubility with solvents (NMP etc.) is reduced, the steric repulsion layer can not be formed, and the dispersibility is inferior. It will be. However, in the present invention, as the reason that the resin (A2a) having the above-mentioned polymerizable unsaturated group-containing monomer (A2a-1) as one of the constituent components exerts an effect on the dispersibility of the conductive paste, it is specified to the side chain of the resin By introducing a functional group of the above, the relatively bulky side chain functional group causes steric hindrance, thereby lowering the melting point of the resin, and reducing the crystallinity of the resin by hydrogen bonding of specific hydroxyl groups. Therefore, it is considered that the solubility in the solvent and the adsorptivity to the pigment were compatible.

  The resin (A2a) may be produced by a polymerization method known per se, for example, a method of solution polymerization in an organic solvent, but it is not limited thereto. For example, bulk polymerization or emulsification It may be polymerization, suspension polymerization or the like. When solution polymerization is performed, continuous polymerization or batch polymerization may be performed, and the monomers may be charged all at once, divided and added, or may be continuously or intermittently added.

  The polymerization initiator used in the solution polymerization is not particularly limited. Specifically, for example, azobisisobutyronitrile, azobis-2,4-dimethylparellonitrile, azobis (4-methoxy-2 Azo compounds such as 4, 4-dimethylpaleronitrile); peroxides such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxy acetate, etc. Percarbonate compounds such as diisopyrpyr peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, etc .; t-Butyl peroxy neodecanate, α-cumyl peroxy neodecanate , T-butyl per Perester compounds such as carboxymethyl neodecanate; azobisdimethylvaleronitrile can be used a known radical polymerization initiator such as azo-bis-methoxy valeronitrile.

  The polymerization reaction temperature is not particularly limited, but can usually be set in the range of about 30 to 200 ° C.

  The conditions for saponification are not particularly limited, and can be saponified by a known method. For example, it can be carried out by hydrolyzing the ester moiety in the molecule in the presence of an alkali catalyst or an acid catalyst in an alcohol solution such as methanol.

  As the alkali catalyst, for example, hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate and the like, alcoholates and the like can be used. As an acid catalyst, for example, an inorganic acid aqueous solution such as hydrochloric acid or sulfuric acid, or an organic acid such as p-toluenesulfonic acid can be used, and sodium hydroxide is preferably used.

  The temperature of the saponification reaction is not particularly limited, but is preferably in the range of 10 to 70 ° C., more preferably 30 to 40 ° C. The reaction time is not particularly limited, but is preferably in the range of 30 minutes to 3 hours.

  The resin (A2a) can be converted into a solid or a resin solution replaced with an optional solvent by desolvation and / or solvent substitution after the completion of synthesis. As the substitution solvent, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, propylene glycol monomethyl ether, alcohol solvents and the like are preferable.

  The solvent may be removed by heating at normal pressure or may be removed under reduced pressure. As a method of solvent substitution, the substitution solvent may be introduced at any stage before solvent removal, during solvent removal, or after solvent removal.

Sulfonic acid modified polyvinyl alcohol resin (A2b)
The sulfonic acid-modified polyvinyl alcohol resin (A2b) is a polyalcohol resin to which a sulfonic acid is imparted by the following production method. Moreover, polyvinyl alcohol resin (A2b) does not contain the polymerizable unsaturated group containing monomer (A2a-1) shown by said Formula (1), and it can distinguish with polyvinyl alcohol resin (A2a) clearly.
(1) A method of further saponifying a polymer obtained by copolymerizing a compound having a sulfonic acid group and a polymerizable unsaturated group with a fatty acid vinyl ester such as vinyl acetate.
(2) A method of Michael addition of vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and the like to polyvinyl alcohol.
(3) A method of heating polyvinyl alcohol with a sulfuric acid compound solution (a sulfuric acid aqueous solution, a sodium sulfite aqueous solution or the like).
(4) A method of acetalizing polyvinyl alcohol with a sulfonic acid group-containing aldehyde compound.
(5) A method of polymerizing polyvinyl alcohol by causing a compound having a functional group such as alcohol having an sulfonic acid group, aldehyde and thiol to coexist as a chain transfer agent.

  Although any production method can be suitably used, a compound having a sulfonic acid group and a polymerizable unsaturated group of (1) and other polymerizable unsaturated monomers (particularly fatty acid vinyl esters such as vinyl acetate are particularly preferable) And the method of further saponifying the polymer obtained by copolymerizing with.

  As the above-mentioned compound containing a sulfonic acid group and a polymerizable unsaturated group (sometimes referred to herein as a polymerizable unsaturated monomer having a sulfonic acid group), a compound capable of copolymerizing with a fatty acid vinyl ester As long as it is not particularly limited, specifically, for example, olefin sulfonic acids such as vinyl sulfonic acid, isoprene sulfonic acid, ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid; sodium sulfopropyl 2-ethylhexyl Sulfoalkyl malates such as malate, sodium sulfopropyl tridecyl malate, sodium sulfopropyl eicosyl malate; sulfoalkyl (meth) such as 2- (meth) acrylamido-2-methylpropane sulfonic acid, sodium N-sulfoisobutylene acrylamide Ak Luamide; 3-methacryloyloxypropane sulfonic acid, 4-methacryloyloxybutane sulfonic acid, 3-methacryloyloxy-2-hydroxypropane sulfonic acid, 3-acryloyloxypropane sulfonic acid, sulfoethyl (meth) acrylate, sodium methacrylate-4- Sulfoalkyl (meth) acrylates such as styrene sulfonate, sodium 2-sulfoethyl acrylate; allyloxybenzenesulfonic acid, methallyloxybenzenesulfonic acid, styrenesulfonic acid, oleyl 2-hydroxy- [3-allyloxy] -propylsulfosuccinate Ammonium salts etc. are mentioned, These can be used individually by 1 type or in combination of 2 or more types.

  In the present invention, the sulfonic acid group may be in the form of a free acid, or in the form of an alkali metal salt such as sodium salt or potassium salt, ammonium salt and the like.

  The content of the polymerizable unsaturated monomer having a sulfonic acid group in the sulfonic acid-modified polyvinyl alcohol resin (A2b) is preferably 0.1 to 10% by mass, and more preferably 0.2 to 5% by mass. In the present invention, the “content ratio of the monomer having a sulfonic acid group in the resin (A2b)” means the content ratio of the monomer having a sulfonic acid group in the monomer mixture as a raw material of the resin (A2b). Therefore, the content ratio of the monomer having a sulfonic acid group in the resin (A2b) is 0.1 to 10% by mass, that the resin (A2b) is 0.1 to 10 mass of a monomer having a sulfonic acid group. It means that it is a copolymer of the raw material monomer containing%.

  The other polymerizable unsaturated monomers copolymerized with the above-mentioned compound containing a sulfonic acid group and a polymerizable unsaturated group are particularly limited as long as they are monomers copolymerizable with a polymerizable unsaturated monomer having a sulfonic acid group. It can be used without. [However, it limits to monomers other than the said polymerizable unsaturated group containing monomer (A2a-1). Specifically, for example, fatty acid vinyl esters such as vinyl acetate; olefin monomers such as ethylene and propylene; (meth) acryloyl group-containing monomers such as alkyl (meth) acrylate; allyl ethers such as allyl glycidyl ether; vinyl chloride And halogenated vinyl compounds such as vinylidene chloride and vinyl fluoride; and vinyl ethers such as alkyl vinyl ethers. These can be used singly or in combination of two or more, and among them, fatty acid vinyl esters are preferred. Among fatty acid vinyl esters exemplified as the fatty acid vinyl ester (A2a-2), one or two or more can be suitably used as the fatty acid vinyl ester, and among these, vinyl acetate is preferable.

  The saponification degree of the sulfonic acid-modified polyvinyl alcohol resin (A2b) is preferably in the range of 30 to 100 mol%, more preferably in the range of 50 to 100 mol%, and in the range of 86 to 100 mol% It is more preferable that it is, and it is especially preferable that it is in the range of 88-99.9 mol%.

  Usually, when the degree of saponification (high polarity) is high, the adsorptivity to inorganic pigments such as carbon is improved, but the solubility with solvents (NMP etc.) is reduced, the steric repulsion layer can not be formed, and the dispersibility is inferior. It will be. However, in the present invention, as a reason that the sulfonic acid-modified polyvinyl alcohol resin (A2b) exerts an effect on the dispersibility of the conductive paste, a relatively bulky side chain is obtained by introducing a specific functional group into the side chain of the resin. The functional group (functional group containing sulfonic acid) causes steric hindrance to lower the melting point of the resin, and the highly polar side chain functional group (functional group containing sulfonic acid) lowers the crystallinity of the resin It can be considered that the solubility in the solvent and the adsorptivity to the pigment are compatible because it can be

  As a polymerization method of the above resin (A2b), the same method as the resin (A2a) described above can be used.

Polyvinyl alcohol resin (A2c) other than resin (A2a) and resin (A2b)
The dispersion resin (A) may contain a polyvinyl alcohol resin (A2c) having a saponification degree of 30 to 100 mol% which does not contain the polymerizable unsaturated group-containing monomer (A2a-1) and is not subjected to sulfonic acid modification. it can. In the present invention, the “polyvinyl alcohol resin not containing the polymerizable unsaturated group-containing monomer (A2a-1)” means (co) polymerization of a raw material monomer not containing the polymerizable unsaturated group-containing monomer (A2a-1) The obtained polyvinyl alcohol resin is meant. In addition, “a polyvinyl alcohol resin not subjected to sulfonic acid modification” refers to a polyvinyl alcohol resin or a polyvinyl alcohol resin obtained by (co) polymerization of a raw material monomer not containing a sulfonic acid group, such as a sulfonic acid group It means a resin not added.

  The polyvinyl alcohol resin (A2c) can be obtained by a polymerization method known per se, for example, by polymerizing and hydrolyzing a fatty acid vinyl ester represented by vinyl acetate.

  As said fatty-acid vinyl ester, 1 type (s) or 2 or more types can be used suitably among fatty-acid vinyl ester illustrated by fatty-acid vinyl ester (A2a-2), Among these, vinyl acetate is preferable.

  The polyvinyl alcohol resin (A2c) can be obtained by copolymerizing with a polymerizable unsaturated monomer other than fatty acid vinyl ester. [However, it is limited to monomers other than the said polymerizable unsaturated group containing monomer (A2a-1) and the polymerizable unsaturated monomer which has a sulfonic acid group. The polymerizable unsaturated monomer copolymerizable with the fatty acid vinyl ester is not particularly limited as long as it is a monomer other than the polymerizable unsaturated group-containing monomer (A2a-1) and the polymerizable unsaturated monomer having a sulfonic acid group. For example, olefin monomers such as ethylene and propylene; (meth) acryloyl group-containing monomers such as alkyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and glycidyl (meth) acrylate; allyl glycidyl ether And allyl ethers such as vinyl chloride, vinylidene chloride compounds such as vinyl chloride, vinylidene chloride and vinyl fluoride, and vinyl ethers such as alkyl vinyl ether and 4-hydroxy vinyl ether. These can be used singly or in combination of two or more.

  The following description will be made mainly with reference to vinyl acetate, but the present invention is not limited thereto.

  The polymerization method of the polyvinyl alcohol resin (A2c) is a polymerization method known per se, for example, a method of solution polymerization of vinyl acetate in an alcohol-based organic solvent to produce polyvinyl acetate and saponification thereof. Although it can manufacture, it is not restricted to this, For example, bulk polymerization, emulsion polymerization, suspension polymerization, etc. may be sufficient. When solution polymerization is carried out, continuous polymerization or batch polymerization may be carried out, and the monomers may be charged all at once, divided and charged, or may be added continuously or intermittently.

  The polymerization initiator used in the solution polymerization is not particularly limited. Specifically, for example, azobisisobutyronitrile, azobis-2,4-dimethylparellonitrile, azobis (4-methoxy-2 Azo compounds such as 4, 4-dimethylpaleronitrile); peroxides such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxy acetate, etc. Percarbonate compounds such as diisopyrpyr peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, etc .; t-Butyl peroxy neodecanate, α-cumyl peroxy neodecanate , T-butyl per Perester compounds such as carboxymethyl neodecanate; azobisdimethylvaleronitrile can be used a known radical polymerization initiator such as azo-bis-methoxy valeronitrile.

  The polymerization reaction temperature is not particularly limited, but can usually be set in the range of about 30 to 200 ° C.

  The saponification conditions at the time of manufacturing polyvinyl alcohol resin (A2c) are not specifically limited, It can saponify by a well-known method. Generally, it can be carried out by hydrolyzing the ester moiety in the molecule in the presence of an alkali catalyst or an acid catalyst in an alcohol solution such as methanol.

  As the alkali catalyst, for example, hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate and the like, alcoholates and the like can be used. As an acid catalyst, for example, an inorganic acid aqueous solution such as hydrochloric acid or sulfuric acid, or an organic acid such as p-toluenesulfonic acid can be used, and sodium hydroxide is preferably used.

  The temperature of the saponification reaction is not particularly limited, but is preferably in the range of 10 to 70 ° C., more preferably 30 to 40 ° C. The reaction time is not particularly limited, but is preferably in the range of 30 minutes to 3 hours.

The polyvinyl alcohol resin obtainable in this manner preferably has a degree of polymerization of 100 to 4,000, and more preferably 100 to 3,000.
The degree of saponification is usually in the range of 30 to 100 mol%, preferably in the range of 32 to 94 mol%.

In the present invention, the degree of saponification of the polyvinyl alcohol resin (A2c) refers to the proportion (mol%) of those in which the ester bond is hydrolyzed among the structural units derived from fatty acid vinyl ester contained in the polyvinyl alcohol resin (A2c) means. The degree of saponification can be measured by completely saponifying the polyvinyl alcohol resin with an alkaline substance such as sodium hydroxide and measuring the amount of fatty acid salt (eg acetate) obtained. (It can be confirmed by infrared absorption analysis whether completely saponified.)
The polyvinyl alcohol resin (A2c) may be a commercially available product.

  The polyvinyl alcohol resin (A2c) can be converted to a solid or a resin solution replaced with any solvent by desolvation and / or solvent substitution after completion of synthesis. As the substitution solvent, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, propylene glycol monomethyl ether, alcohol solvents and the like are preferable.

  The solvent may be removed by heating at normal pressure or may be removed under reduced pressure. As a method of solvent substitution, the substitution solvent may be introduced at any stage before solvent removal, during solvent removal, or after solvent removal.

  In the conductive paste of the present invention, the resins are made compatible by using the highly polar resin (A2a) and / or (A2b) and the relatively low polar polyvinyl alcohol resin (A2c) in combination, and the resin mixture makes it possible to It is considered that the solvent solubility and the pigment adsorption are further compatible.

  When the resin (A1) having a polycyclic aromatic hydrocarbon group and the polyvinyl alcohol resin (A2) are contained in the dispersion resin (A), the blending ratio is not limited, but the solid content 100 mass of the dispersion resin (A) The solid content of the resin (A1) having a polycyclic aromatic hydrocarbon group is usually 5 to 95 parts by mass, preferably 10 to 50 parts by mass, and the solid content of the polyvinyl alcohol resin (A2) is preferably It is preferable from the viewpoint of viscosity and battery performance that the range is usually 5 to 95 parts by mass, preferably 50 to 90 parts by mass. When the polyvinyl alcohol (A2) contains both the polyvinyl alcohol resin (A2a) and / or (A2b) and the polyvinyl alcohol (A2c), the blending ratio is not limited, but the polyvinyl alcohol resin (A2a) and the resin (A2b) And the solid content of the polyvinyl alcohol (A2c) is usually in the range of 5 to 100 parts by mass, preferably 15 to 70 parts by mass with respect to 100 parts by mass of the solid content obtained by adding preferable.

In the other dispersion resin dispersion resin (A), resins other than the above resin (A1) and resin (A2) may be optionally blended. For example, acrylic resin other than resin (A1) and resin (A2), polyester resin, epoxy resin, polyether resin, alkyd resin, urethane resin, silicone resin, polycarbonate resin, polycarbonate resin, silicate resin, chlorine resin, polyvinylidene fluoride (PVDF ), Polyvinyl pyrrolidone resins, polyvinyl alcohol resins, polyvinyl acetal resins, composite resins of these, and the like. These resins can be used alone or in combination of two or more. Among them, it is preferable to use at least one resin selected from polyvinyl acetal resin, polyvinyl pyrrolidone resin and fluorine resin in combination. Moreover, these resins can be mix | blended with a conductive paste as pigment dispersion resin or as addition resin after pigment dispersion.

Conductive carbon (B)
As the conductive carbon (B), conductive carbon used in the field of the battery to which the present invention belongs can be appropriately used. Examples of the conductive carbon (B) include acetylene black, furnace black, thermal black, channel black, ketjen black, vulcan, carbon nanotubes, graphene, vapor grown carbon fiber (VGCF), graphite and the like. Preferably, acetylene black, graphite and the like are mentioned, and more preferably acetylene black and the like are mentioned. In a preferred embodiment of the present invention, the conductive carbon (B) may contain both acetylene black and graphite. These conductive carbons can be used singly or in combination of two or more.

Solvent (D)
As the solvent (D), those widely known in the field of conductive pastes for lithium ion battery positive electrodes can be widely used, and are used for polymerization or dilution of the above-described resin (A1) having a polycyclic aromatic hydrocarbon group Solvents other than water can be suitably used. Specific examples of preferred solvents (D) include, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, propylene glycol monomethyl ether, methanol and the like, preferably N-methyl-2-pyrrolidone and the like. Can be mentioned. These solvents can be used alone or in combination of two or more.

Other Components The conductive paste for lithium ion battery positive electrode may contain components other than the above components (A), (B), (C) and (D), for example, polyvinylidene fluoride (E), dehydration Agents and additives can be used, and in particular, polyvinylidene fluoride is preferably used.

Polyvinylidene fluoride (E)
As said polyvinylidene fluoride, the thing of a cultivated land can be widely used in the field | area of the electrically conductive paste for lithium ion battery positive electrodes to which an invention belongs. The weight-average molecular weight of polyvinylidene fluoride is not particularly limited, but usually 10,000 to 2,000,000 is preferable, 50,000 to 1,700,000 is more preferable, and 100,000 to 1,500,000 is particularly preferable. preferable. The polyvinylidene fluoride may be used as a dispersion resin of conductive carbon, or may be added after dispersion of conductive carbon. When using polyvinylidene fluoride (E), the solid content of polyvinylidene fluoride (E) in the conductive paste solid content for lithium ion battery positive electrode is usually 1% by mass or more and less than 30% by mass, preferably 2 From the viewpoint of battery performance, mass% or more and less than 25% by mass, more preferably 4% by mass or more and less than 20% by mass are preferable.

Dehydrating Agent As the above dehydrating agent, any known one can be used without particular limitation as long as it has a dehydrating action. It may be a solid dehydrating agent that does not dissolve in the solvent (D) of the conductive paste, or may be a dehydrating agent that dissolves in the solvent (D). Specifically, for example, solid dehydrating agents such as zeolite, silica gel, calcium oxide, molecular sieve, activated alumina, barium oxide, calcium hydride and sodium sulfate; trimethyl phosphate, tri-2-propyl phosphate, tributyl phosphate Phosphoric acid esters such as tetraisopropyl ethylene phosphonate; phosphine oxides such as tolubutyl phosphine oxide, trioctyl phosphine oxide, triphenyl phosphine oxide; ortho formate methyl ester, ortho formate ethyl ester, ortho acetate methyl ester, ortho acetate ethyl ester, Ortho esters such as orthobenzoic acid ethyl ester; oxalic anhydride, acetic anhydride, propionic acid anhydride, butyric anhydride, benzoic acid anhydride, trifluoroacetic acid anhydride Disulfuric acid, dinitrogen pentoxide, diphosphoric acid, diphosphorus pentoxide, diphosphorus trioxide, diarsenic pentoxide, diarsenic pentoxide, diarsenic trioxide, methanesulfonic acid anhydride, trifluoromethanesulfonic acid anhydride, sulfobenzoic acid anhydride And acid anhydrides, etc., and these can be used alone or in combination of two or more.

Additives As additives, for example, neutralizing agents, pigment dispersants, antifoaming agents, preservatives, rust inhibitors, plasticizers, binders (binders) and the like can be mentioned.

  As a pigment dispersant and / or binder, for example, acrylic resin other than the dispersion resin (A) and polyvinylidene fluoride, polyester resin, epoxy resin, polyether resin, alkyd resin, urethane resin, silicone resin, polycarbonate resin And silicate resins, chlorine resins, fluorine resins, polyvinyl pyrrolidone resins, polyvinyl alcohol resins, polyvinyl acetal resins, and composite resins of these, and the like. These resins can be used alone or in combination of two or more.

Method of producing conductive paste for lithium ion battery positive electrode The conductive paste for lithium ion battery positive electrode of the present invention can be obtained by, for example, paint shaker, sand mill, ball mill, pebble mill, LMZ mill, DCP pearl mill, planetary ball mill, It can be prepared by uniformly mixing and dispersing using a conventionally known disperser such as a homogenizer, a twin-screw kneader, a thin film swirl type high speed mixer or the like.

  The conductive paste for a lithium ion battery positive electrode according to the present invention can be used for producing a mixture paste for a lithium ion battery positive electrode by being mixed with an electrode active material as described later.

Mixture paste for lithium ion battery positive electrode The present invention provides a mixture paste for lithium ion battery positive electrode, which is obtained by further blending an electrode active material with the above-described conductive paste for lithium ion battery positive electrode of the present invention.

Electrode Active Material As the electrode active material, an electrode active material used in the field of batteries to which the present invention belongs can be appropriately used. A wide range of materials known in the field of lithium ion battery positive electrode mixture paste can be used. For example, lithium composite oxides such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium cobaltate (LiCoO ₂ ), LiNi _1/3 Co _1/3 Mn _1/3 O _{2 and the} like It can be mentioned. These electrode active materials can be used singly or in combination of two or more. The solid content of the electrode active material in the solid material of the mixture paste for lithium ion battery positive electrode of the present invention is usually 30% by mass or more and less than 99% by mass, preferably 50% by mass or more and less than 95% by mass It is preferable from the viewpoint of battery capacity, battery resistance, etc.

  The amount of lithium hydroxide can be measured by a method in which the electrode active material is excessively diluted with a solvent such as deionized water and centrifuged, and then the supernatant is subjected to neutralization titration with hydrochloric acid.

  The total amount of solid content of the dispersion resin (A) in the solid content of the mixture paste for lithium ion battery positive electrode of the present invention is usually 0.001 to 20% by mass, preferably 0.005 to 10% by mass Is preferable in terms of battery performance, paste viscosity, and the like.

  The solid content of the conductive carbon (B) in the solid content of the mixture paste for a lithium ion battery positive electrode of the present invention is usually 0.01 to 30% by mass, preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass is preferable in terms of battery performance.

  The content of the solvent (D) in the mixture paste for a lithium ion battery positive electrode of the present invention is usually 0.1 to 60% by mass, preferably 0.5 to 50% by mass, more preferably 1 to 45% by mass Is preferred in terms of electrode drying efficiency and paste viscosity.

  When using polyvinylidene fluoride (E), the solid content of polyvinylidene fluoride in the solid content of the mixture paste for lithium ion battery positive electrode of the present invention is usually 0% by mass or more and less than 3% by mass, preferably 0.1 mass% or more and less than 2.5 mass%, more preferably 0.5 mass% or more and less than 2 mass% are suitable.

  As a manufacturing method of the mixture paste for lithium ion battery positive electrodes of the present invention, it can obtain by, for example, preparing the conductive paste for lithium ion battery positive electrodes mentioned above first, and mixing an electrode active material with the conductive paste concerned.

  Moreover, as a use of the electrically conductive paste for lithium ion battery positive electrodes obtained by the manufacturing method of this invention, it can use also as a primer layer between a positive electrode core material and a synthetic layer other than using as a paste of a composite material layer .

Lithium ion battery positive electrode The present invention provides a lithium ion battery positive electrode obtained by using the above-mentioned lithium ion battery positive electrode mixture paste of the present invention.

  As described above, the lithium ion battery positive electrode can be manufactured by applying the lithium ion battery positive electrode mixture paste on the surface of the positive electrode core material and drying it. Moreover, as a use of the electrically conductive paste for lithium ion battery positive electrodes obtained by the manufacturing method of this invention, it can use also as a primer layer between a positive electrode core material and a synthetic layer other than using as a paste of a composite material layer .

  The method of applying the lithium ion battery positive electrode mixture paste can be performed by a method known per se using a die coater or the like. Although the application amount of the lithium ion battery positive electrode mixture paste is not particularly limited, for example, the thickness of the dried positive electrode mixture layer is in the range of 0.04 to 0.30 mm, preferably 0.06 to 0.24 mm. It can be set as As a temperature of a drying process, it can set suitably within the limits of 80-200 ° C, preferably 100-180 ° C, for example. As time of a drying process, it can set suitably within the limits of 5 to 120 seconds, preferably 5 to 60 seconds, for example.

  The present invention will be more specifically described by way of the following examples.

  Hereinafter, the present invention will be described in more detail by way of Production Examples, Examples and Comparative Examples, but the present invention is not limited thereto. "Part" in each example shows a mass part and "%" shows the mass%.

Production of dispersed resin (A)
Production Example 1 of Polycyclic Aromatic Ring-Containing Resin
In a reaction vessel equipped with a stirring heater and a cooling pipe, 300 parts of propylene glycol monomethyl ether was charged, and after nitrogen substitution, the temperature was maintained at 105 ° C. Into this, the monomer mixture shown below was dropped over 3 hours.
<Monomer mixture>
4-hydroxy-1-naphthyl methacrylate 250 parts 2-methoxy-4-hydroxy-1-naphthyl acrylate 250 parts styrene 50 parts 2-hydroxyethyl acrylate 50 parts N, N-dimethyl acrylamide 200 parts N-ethyl-N-hydroxyethyl Acrylamide 200 parts 2,2'-azobis (2-methylbutyronitrile) 40 parts After 1 hour from the end of dropwise addition, 5 parts of 2,2'-azobis (2-methylbutyronitrile) in propylene glycol A solution dissolved in 100 parts of monomethyl ether was added dropwise over 1 hour. After completion of the dropwise addition, this was kept at 105 ° C. for one hour, discharged and dried by a hot air drier. Finally, the polycyclic aromatic ring-containing resin No. 1 having a solid content of 100%. I got one. Polycyclic aromatic ring containing resin No. The weight average molecular weight of 1 was 11,000.

Production Example 2
Polycyclic aromatic ring-containing resin No. 1 was prepared by the same composition and production method as in Production Example 1 except that the monomer composition in Production Example 1 was changed to the type and blending amount in Table 1 below. 2 produced. (The weight average molecular weight was 11,000.)

Production Example 3 of Polyvinyl Alcohol Resin
In a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, 90 parts by mass of vinyl acetate as a polymerizable monomer and 10 parts by mass of 2-butene-1,4-diol, methanol as a solvent, polymerization start After copolymerization reaction of azobisisobutyronitrile as an agent at a temperature of about 60 ° C., unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, for polyvinyl alcohol resin No. 1 having a degree of polymerization of 300 and a degree of saponification of 95 mol%. I got one.

Production Example 4
In a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, 90 parts by mass of vinyl acetate as a polymerizable monomer and 10 parts by mass of 1-butene-3,4-diol, methanol as a solvent, polymerization initiation After copolymerization reaction was performed at a temperature of about 60 ° C. using azobisisobutyronitrile as an agent, unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, for polyvinyl alcohol resin No. 1 having a degree of polymerization of 300 and a degree of saponification of 95 mol%. I got two.

Production Example 5
In a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, 90 parts by mass of vinyl acetate as a polymerizable monomer and 10 parts by mass of 1-pentene-4,5-diol, methanol as a solvent, polymerization initiation After copolymerization reaction was performed at a temperature of about 60 ° C. using azobisisobutyronitrile as an agent, unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, for polyvinyl alcohol resin No. 1 having a degree of polymerization of 300 and a degree of saponification of 95 mol%. I got three.

Production Example 6
In a reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe, and a stirrer, 97 parts by mass of vinyl acetate as a polymerizable monomer and 3.0 parts by mass of sodium allylsulfonate, methanol as a solvent, azo as a polymerization initiator After the copolymerization reaction was carried out using bisisobutyronitrile at a temperature of about 60 ° C., unreacted monomers were removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, for polyvinyl alcohol resin No. 1 having a degree of polymerization of 300 and a degree of saponification of 95 mol%. I got four.

Production Example 7
A reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, using vinyl acetate as a polymerizable monomer, methanol as a solvent, azobisisobutyronitrile as a polymerization initiator, and a temperature of about 60 ° C. After the copolymerization reaction was carried out, the unreacted monomer was removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, for polyvinyl alcohol resin No. 5 having a degree of polymerization of 500 and a degree of saponification of 57 mol%. I got five.

Production Example 8
A reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, using vinyl acetate as a polymerizable monomer, methanol as a solvent, azobisisobutyronitrile as a polymerization initiator, and a temperature of about 60 ° C. After the copolymerization reaction was carried out, the unreacted monomer was removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, polyvinyl alcohol resin No. 5 having a degree of polymerization of 500 and a degree of saponification of 75 mol%. I got six.

Production Example 9
A reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet pipe and a stirrer, using vinyl acetate as a polymerizable monomer, methanol as a solvent, azobisisobutyronitrile as a polymerization initiator, and a temperature of about 60 ° C. After the copolymerization reaction was carried out, the unreacted monomer was removed under reduced pressure to obtain a resin solution. Next, a saponification reaction was carried out by adding a methanol solution of sodium hydroxide, thoroughly washed, and then dried with a hot air drier. Finally, polyvinyl alcohol resin No. 1 having a degree of polymerization of 500 and a degree of saponification of 92 mol% was used. I got seven.

Production Example 1 of Conductive Paste
Polycyclic aromatic ring-containing resin No. 1 obtained in Production Example 1 6 parts (solid part 6 parts), polyvinyl alcohol resin No. 1 obtained in Production Example 4 9 parts (solid part 9 parts), polyvinyl alcohol resin No. 1 obtained in Production Example 5 No. 3 9 parts (solid part 9 parts), polyvinyl alcohol resin No. 1 obtained in Production Example 9 7 parts (solid content: 6 parts), acetylene black: 1200 parts, KF polymer W # 7300 (trade name: polyvinylidene fluoride, Kleha company make, water content: 100 ppm) 220 parts, N-methyl-2-pyrrolidone 8500 parts, and 6 parts of dehydrating agent (1.5 parts of phosphorus pentoxide, 1.5 parts of acetic anhydride, 1.5 parts of methanesulfonic anhydride, 1.5 parts of ethyl orthoformate ester), 0.03 parts of N-hydroxyethyl acrylamide And dispersed in a ball mill for 5 hours to obtain a conductive paste X-1.

Examples 2-14, Comparative Examples 1-5
Conductive pastes X-2 to X-19 were produced in the same manner as in Example 1 except that the following Table 2 was used. In addition, all resin compounding quantities in the table are values of solid content.

Compound paste production example 15
100 parts of conductive paste X-1 obtained in Example 1 and active material particles (lithium nickel manganese oxide particles of spinel structure represented by the composition formula LiNi _0.5 Mn _1.5 O _4. Average particle diameter 6 μm And 150 parts of a BET specific surface area of 0.7 m ² / g) to prepare a mixture paste Y-1.

Examples 16-28, Comparative Examples 6-10
Compound pastes Y-2 to Y-19 were manufactured in the same manner as in Example 15, except that the materials in Table 3 below were used.

  The results (the viscosity of the conductive paste, the storage property of the mixture paste) of the evaluation test to be described later are described in Table 3 above. When the evaluation result of rejection "D" comes out, the conductive paste and the mixture paste are rejection.

Evaluation test <Viscosity of conductive paste>
The viscosity of the conductive paste obtained in Examples and Comparative Examples was measured at a shear rate of 10 sec- ¹ using a cone and plate viscometer "Mars 2" (trade name, manufactured by HAAKE), and evaluated according to the following criteria. As evaluation, S, A, B, and C pass, D fails.
S: The viscosity is less than 1 Pa · s.
A: The viscosity is 1 Pa · s or more and less than 5 Pa · s.
B: The viscosity is 5 Pa · s or more and less than 10 Pa · s.
C: The viscosity is 10 Pa · s or more and less than 20 Pa · s.
D: The viscosity is 20 Pa · s or more.

<Storability of mixture paste>
The material pastes obtained in Examples and Comparative Examples are placed in a sealed container, stored at 50 ° C. for 7 days, and compared with the viscosity before storage. As evaluation, A, B, and C pass, D fails.
A: The viscosity increase rate of the paste after storage is less than 5% compared to before storage.
B: The viscosity increase rate of the paste after storage is 5% or more and less than 10% as compared to that before storage.
C: The viscosity increase rate of the paste after storage is 10% or more and less than 20% compared to before storage.
D: The viscosity increase rate of the paste after storage is 20% or more compared to that before storage.

Claims (8)

It is a conductive paste for lithium ion battery positive electrodes containing dispersion resin (A), conductive carbon (B), (meth) acryloyl group containing compound (C), and solvent (D),
The content of the (meth) acryloyl group-containing compound (C) is 0.002 to 0.3% by mass based on 100 parts by mass of the conductive carbon (B). paste. Furthermore, polyvinylidene fluoride (E) is contained, The electrically conductive paste for lithium ion battery positive electrodes of Claim 1 characterized by the above-mentioned. The conductive paste for a lithium ion battery positive electrode according to claim 1 or 2, wherein the (meth) acryloyl group-containing compound (C) contains a (meth) acrylamide compound (C-1). The conductive paste for a lithium ion battery positive electrode according to claim 3, wherein the (meth) acrylamide compound (C-1) is a hydroxyl group-containing (meth) acrylamide compound (C-2). The molecular weight of a (meth) acryloyl group containing compound (C) is 70-500, The electrically conductive paste for lithium ion battery positive electrodes of any one of the Claims 1-4 characterized by the above-mentioned. The mixed material paste for lithium ion battery positive electrodes formed by mix | blending an electrode active material with the electrically conductive paste of any one of Claims 1-5 further. An electrode for a lithium ion battery positive electrode obtained using the mixture paste for a lithium ion battery positive electrode according to claim 6. A lithium ion battery comprising the lithium ion battery positive electrode according to claim 7.