WO2020090695A1 - Binder for secondary battery electrodes, and use thereof - Google Patents

Binder for secondary battery electrodes, and use thereof Download PDF

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Publication number
WO2020090695A1
WO2020090695A1 PCT/JP2019/042064 JP2019042064W WO2020090695A1 WO 2020090695 A1 WO2020090695 A1 WO 2020090695A1 JP 2019042064 W JP2019042064 W JP 2019042064W WO 2020090695 A1 WO2020090695 A1 WO 2020090695A1
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mass
binder
meth
structural unit
polymer
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PCT/JP2019/042064
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French (fr)
Japanese (ja)
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篤史 西脇
直彦 斎藤
松崎　英男
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東亞合成株式会社
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Priority to JP2020553866A priority Critical patent/JPWO2020090695A1/en
Publication of WO2020090695A1 publication Critical patent/WO2020090695A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/04—Acids; Metal salts or ammonium salts thereof
    • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/20—Esters of polyhydric alcohols or phenols, e.g. 2-hydroxyethyl (meth)acrylate or glycerol mono-(meth)acrylate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present specification relates to a binder for a secondary battery electrode and its use.
  • This application is a related application of Japanese Patent Application No. 2018-205228 filed on Oct. 31, 2018, and claims the priority right based on this Japanese application. Incorporated herein by reference.
  • the electrodes used in these secondary batteries are produced by applying a composition for forming an electrode mixture layer containing an active material, a binder and the like onto a current collector and drying the composition.
  • a composition for forming an electrode mixture layer containing an active material, a binder and the like onto a current collector and drying the composition.
  • an aqueous binder containing styrene-butadiene rubber (SBR) latex and carboxymethyl cellulose (CMC) is used as a binder used in the negative electrode mixture layer composition.
  • Patent Document 1 A binder using the above acrylic acid-based polymer has been proposed as a binder having good binding properties and an effect of improving durability.
  • Patent Document 2 by using a polymer obtained by crosslinking polyacrylic acid with a specific cross-linking agent as a binder, the electrode structure is not destroyed even when an active material containing silicon is used. It is described that it can be provided.
  • Patent Document 2 discloses a crosslinked polymer having a carboxy group or a salt thereof, which is obtained by using a binder containing a polymer having a sufficiently small particle size when dispersed in salt water after neutralization, It is described that it exhibits excellent binding properties.
  • the binders disclosed in each patent document are all capable of imparting good binding properties, but as the performance of the secondary battery is improved, an electrode mixture layer having higher binding properties is required. It has become. Further, when the amount of the binder is increased in order to improve the binding property, the slurry viscosity of the electrode mixture layer composition becomes high and the coatability is deteriorated. Therefore, there is a demand for a binder that can reduce the viscosity of the slurry.
  • the present specification provides a binder that can improve the binding property and reduce the viscosity of the slurry for the electrode mixture layer, and the use thereof.
  • a secondary battery electrode binder having a crosslinked polymer or a salt thereof comprising: The crosslinked polymer or a salt thereof comprises a non-crosslinked structural unit and a crosslinked structural unit,
  • the non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated carboxylic acid monomer,
  • the cross-linking structural unit has two or more (meth) acryloyl groups in one molecule, and includes a cross-linking structural unit derived from a cross-linkable monomer having a hydroxyl group, binder.
  • a composition for a secondary battery electrode comprising: A binder for a secondary battery electrode according to [1] or [2], Active material, water and, A composition containing: [4] A secondary battery electrode, A binder for a secondary battery electrode according to [1] or [2], Active material, An electrode containing. [5] The electrode according to [4], wherein the active material is a silicon-containing material.
  • a method for manufacturing a binder for a secondary battery electrode comprising: Step of polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer and a crosslinkable monomer having two or more (meth) acryloyl groups in one molecule and having a hydroxyl group , And a manufacturing method.
  • the secondary battery electrode binder (hereinafter, simply referred to as the binder) disclosed in the present specification can include a crosslinked polymer or a salt thereof (hereinafter, simply referred to as the present polymer).
  • the present polymer comprises a non-crosslinked structural unit and a crosslinked structural unit, the non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated monomer, the crosslinked structural unit in one molecule Can have a crosslinked structural unit derived from a crosslinkable monomer having two or more (meth) acryloyl groups and having a hydroxyl group.
  • the present polymer contains, in the cross-linking structural unit, a cross-linking structural unit derived from a cross-linking monomer having two or more (meth) acryloyl groups. Since such a crosslinkable monomer has a relatively high radical polymerizability, a crosslinked structural unit is formed relatively uniformly from the inside of the polymer particle to the surface portion.
  • the cross-linking density of the present polymer particle surface obtained by cross-linking polymerization can be suppressed from being excessively increased, and as a result, the degree of swelling of the present polymer particle surface in water is relatively high, and the active material or It is considered that the adhesive area with the current collector can be secured and the binder containing the present polymer particles exhibits good binding properties.
  • the present polymer has a hydroxyl group in the cross-linking structural unit, the swelling degree of the present polymer particle is suppressed by the interaction (hydrogen bond etc.) due to the hydroxyl group in the polymer particle, and the increase of slurry viscosity is suppressed. can do.
  • the secondary battery electrode composition contains the present binder, it is easy to apply. Moreover, the secondary battery electrode containing the present binder exhibits excellent binding properties. Further, according to the present binder production method, secondary battery electrode composition and secondary battery electrode production method, it is possible to provide an electrode having excellent binding properties by suppressing an increase in viscosity during preparation of the electrode slurry. it can.
  • the present binder contains the present polymer, and by mixing with an active material and water, a secondary battery electrode composition (electrode mixture layer composition, hereinafter, also simply referred to as the present composition). can do.
  • the composition may be in a slurry state in which it can be applied to a current collector, or may be prepared in a wet powder state so that it can be pressed to the surface of the current collector.
  • the secondary battery electrode disclosed in the present specification hereinafter, also simply referred to as the present electrode. Is obtained.
  • (meth) acrylic means acrylic and / or methacrylic
  • (meth) acrylate means acrylate and / or methacrylate
  • (meth) acryloyl group means an acryloyl group and / or a methacryloyl group.
  • the binder may include the polymer, that is, a crosslinked polymer or a salt thereof.
  • the present binder may contain only the present polymer, or may contain other binder components as described later.
  • the present polymer is contained in an amount of 50% by mass or more of the binder component, for example 60% by mass or more, for example 70% by mass or more, for example 80% by mass or more, and for example 90% by mass or more. It is contained, for example, 95% by mass or more, and for example, 100% by mass.
  • the polymer has a non-crosslinked structural unit and a crosslinked structural unit.
  • the non-crosslinking structural unit is not particularly limited, and includes structural units derived from various non-crosslinking monomers that can be used in the crosslinked polymer that can be used as the binder of the secondary battery electrode, as the noncrosslinking structural unit. be able to.
  • the non-crosslinked structural unit may have, for example, a structural unit derived from an ethylenically unsaturated carboxylic acid monomer (hereinafter, also referred to as “component (a)”).
  • component (a) ethylenically unsaturated carboxylic acid monomer
  • the above structural unit can be introduced into the present polymer by, for example, polymerizing a monomer containing an ethylenically unsaturated carboxylic acid monomer.
  • it can also be obtained by (co) polymerizing a (meth) acrylic acid ester monomer and then hydrolyzing it. Moreover, after polymerizing (meth) acrylamide, (meth) acrylonitrile, etc., it may be treated with a strong alkali or a method of reacting an acid anhydride with the main polymer having a hydroxyl group.
  • Examples of the ethylenically unsaturated carboxylic acid monomer include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamidoalkyl acid such as (meth) acrylamidohexanoic acid and (meth) acrylamidododecanoic acid.
  • Carboxylic acid ethylenically unsaturated monomers having a carboxy group such as succinic acid monohydroxyethyl (meth) acrylate, ⁇ -carboxy-caprolactone mono (meth) acrylate, ⁇ -carboxyethyl (meth) acrylate or the like (part thereof) )
  • Alkali-neutralized products are mentioned, and one of them may be used alone, or two or more thereof may be used in combination.
  • a polymer having a long primary chain length is obtained because of a high polymerization rate, and a compound having an acryloyl group as a polymerizable functional group is preferable in that the binding force of the binder is good, and acrylic acid is particularly preferable. is there.
  • acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer having a high carboxy group content can be obtained.
  • the carboxy group of the ethylenically unsaturated carboxylic acid monomer may be free or at least a part thereof may be a salt.
  • the type of salt is not particularly limited, but alkali metal salts such as lithium, sodium and potassium; alkaline earth metal salts such as calcium salt and barium salt; other metal salts such as magnesium salt and aluminum salt; ammonium salt and organic salt Examples thereof include amine salts.
  • alkali metal salts and magnesium salts are preferable, and alkali metal salts are more preferable, because they are unlikely to adversely affect battery characteristics.
  • a particularly preferred alkali metal salt is a lithium salt.
  • the content of the component (a) in the present polymer is not particularly limited, but may be, for example, 10% by mass or more and 100% by mass or less based on the total amount of the non-crosslinked structural units of the present polymer.
  • the lower limit is, for example, 20% by mass or more, for example, 30% by mass or more, and for example, 40% by mass or more.
  • the lower limit may be 50% by mass or more, for example 60% by mass or more, for example 70% by mass or more, and for example 80% by mass or more.
  • the adhesiveness to the current collector can be secured, and a good lithium ion desolvation effect and ion conductivity are provided, so that an electrode having excellent high rate characteristics can be obtained.
  • the water swelling property can enhance the dispersion stability of the active material and the like in the present composition. Such an effect tends to be improved by increasing the content of the component (a).
  • the upper limit is 100% by mass, and 100% by mass may be suitable, but is, for example, 99% by mass or less, for example 98% by mass or less, and for example 95% by mass or less, and For example, it is 90 mass% or less.
  • the range of the component (a) can be a range in which the lower limit and the upper limit are appropriately combined.
  • the range is 10% by mass or more and 100% by mass or less based on the total amount of the non-crosslinked structural units of the present polymer.
  • 100% by mass or less and may be, for example, 70% by mass or more and 100% by mass or less.
  • the content of the component (a) with respect to the total amount of the non-crosslinking structural units can be obtained as, for example, the content of the ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinking monomer used in the present polymer.
  • the present polymer may contain, in addition to the component (a), a structural unit derived from another ethylenically unsaturated monomer copolymerizable therewith (hereinafter, also referred to as “component (b)”). ..
  • component (b) include ethylenically unsaturated monomer compounds having anionic groups other than carboxy groups such as sulfonic acid groups and phosphoric acid groups, or nonionic ethylenically unsaturated monomers.
  • component (b) include ethylenically unsaturated monomer compounds having anionic groups other than carboxy groups such as sulfonic acid groups and phosphoric acid groups, or nonionic ethylenically unsaturated monomers.
  • the structural unit from which it is derived is included.
  • These structural units are ethylenically unsaturated monomer compounds having anionic groups other than carboxy groups such as sulfonic acid groups and phosphoric acid groups, or monomers containing nonionic ethylenically unsaturated monomers. Can be introduced by copolymerizing.
  • a structural unit derived from a nonionic ethylenically unsaturated monomer is preferable from the viewpoint of obtaining an electrode having good bending resistance, and the binding property of the binder and the slurry viscosity.
  • (Meth) acrylamide and its derivatives are preferred because of their excellent properties.
  • a structural unit derived from a hydrophobic ethylenically unsaturated monomer having a solubility in water of 1 g / 100 ml or less is introduced as the component (b)
  • strong interaction with the electrode material can be achieved, Good binding properties can be exhibited for the active material. This is preferable because it is possible to obtain a firm and good electrode mixture layer.
  • a structural unit derived from an alicyclic structure-containing ethylenically unsaturated monomer is particularly preferable.
  • (Meth) acrylamide and its derivatives are preferable as the nonionic ethylenically unsaturated monomer because of their excellent binder binding properties and slurry viscosity.
  • the (meth) acrylamide derivative include N-alkyl (s) such as isopropyl (meth) acrylamide, t-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide.
  • (Meth) acrylamide compound; N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide, etc. may be mentioned, and one of these may be used alone, or two of them may be used. The above may be used in combination.
  • the proportion of component (b), which is (meth) acrylamide and its derivative, can be, for example, 0% by mass or more and 90% by mass or less based on the total amount of the non-crosslinked structural units.
  • the proportion of the component (b) is, for example, 1% by mass or more and 70% by mass or less, or 2% by mass or more and 60% by mass or less, or 5% by mass or more and 50% by mass or less, or 10% by mass or more, for example. , 30 mass% or less.
  • nonionic ethylenically unsaturated monomer for example, (meth) acrylic acid ester may be used.
  • (meth) acrylic acid ester examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.
  • (Meth) acrylic acid alkyl ester compound (meth) acrylic acid cycloalkyl ester such as (meth) acrylic acid cyclohexyl, (meth) acrylic acid methylcyclohexyl, etc .; (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid (Meth) acrylic acid alkoxyalkyl ester compounds such as ethoxyethyl; hydroxymethacrylic acid hydroxyalkyl ester compounds such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate Named You may be using one of these alone or may be used in combination of two or more.
  • the ratio of the structural units derived from the (meth) acrylic acid ester is based on the total amount of the non-crosslinked structural units of the present polymer. , Preferably 1 to 30% by mass, more preferably 5 to 30% by mass, and further preferably 10 to 30% by mass.
  • the ratio of the component (a) is preferably 70 to 99% by mass, more preferably 70 to 95% by mass, and further preferably 70 to 99% by mass based on the total structural units of the present polymer. It is 90% by mass.
  • (meth) acrylic acid alkoxyalkyls such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, ethers, etc.
  • a compound having a bond is preferable, and 2-methoxyethyl (meth) acrylate is more preferable.
  • nonionic ethylenically unsaturated monomers a compound having an acryloyl group is preferable in that a polymer having a long primary chain length can be obtained because of its high polymerization rate and the binding force of the binder is good.
  • a compound having a homopolymer glass transition temperature (Tg) of 0 ° C. or lower is preferable in that the obtained electrode has good bending resistance.
  • the present polymer has, as a cross-linking structural unit, two or more (meth) acryloyl groups in one molecule, and a cross-linking structural unit derived from a cross-linkable monomer having a hydroxyl group (hereinafter, referred to as “(c) component”). Also referred to as).
  • the two or more (meth) acryloyl groups that the component (c) may have include two or more methacryloyl groups, one or more acryloyl groups and one or more methacryloyl groups, two or more acryloyl groups. can do. It is not particularly limited, but is, for example, 2 or more and 6 or less (meth) acryloyl group, and is, for example, 2 or more and 5 or less (meth) acryloyl group, or, for example, 2 or more and 4 or less (meth ) An acryloyl group, for example, 2 or more and 3 or less (meth) acryloyl groups, for example, 2 (meth) acryloyl groups can be provided.
  • the (meth) acryloyl group can reduce the crosslink density on the particle surface of the present polymer and reduce the degree of swelling in water.
  • the (meth) acryloyl group contained in the component (c) is more preferably a methacryloyl group. Therefore, when the component (c) is a difunctionalized compound having two (meth) acryloyl groups, the components (c) are, for example, from the viewpoint of improving the binding property, preferred dimethacryloyl groups. , A methacryloyl group, an acryloyl group, and a diacryloyl group.
  • the (meth) acryloyl group contained in the component (c) is more preferably an acryloyl group from the viewpoint of the viscosity of the mixture layer composition (slurry). Therefore, the bifunctional compound includes, for example, a diacryloyl group, a methacryloyl group and an acryloyl group, and a dimethacryloyl group in a preferable order from the viewpoint of suppressing slurry viscosity.
  • the number and combination of (meth) acryloyl groups in the component (c) can be appropriately selected in consideration of the binding property and slurry viscosity intended as a binder for secondary battery electrodes, as well as the amount of the crosslinking structural unit.
  • the number of hydroxyl groups that the component (c) can have is not particularly limited as long as it is 1 or more, and is, for example, 1 or more and 3 or less, or, for example, 1 or more and 2 or less, and For example, one. It is considered that as the number of hydroxyl groups increases, the interaction within the polymer particles tends to increase.
  • the number of hydroxyl groups in the component (c) can be appropriately selected in consideration of the viscosity of the slurry intended as the binder for the secondary battery electrode and the like, as well as the amount of the cross-linking structural unit.
  • the component (c) is not particularly limited, and examples thereof include trimethylolpropane di (meth) acrylate, pentaerythritol di- or tri (meth) acrylate, dipentaerythritol di-, tri-, tetra- or penta- (meta). ) Acrylate, glycerin di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate and the like can be used. As the component (c), only one type may be used, but two or more types may be used in combination.
  • the component (c) is not particularly limited, but is, for example, 0.01 part by mass or more and 20 parts by mass or less when the total amount of the non-crosslinked structural units is 100 parts by mass. If it is less than 0.01 parts by mass, the binding property will not be obtained and the viscosity of the slurry will be too high. If it exceeds 20 parts by mass, the binding property will not be obtained.
  • the component (c) is, for example, 0.02 parts by mass or more, and for example, 0.04 parts by mass or more, for example, 0.05 parts by mass or more, and for example, 0.1 parts by mass or more, Further, for example, it is 0.2 parts by mass or more.
  • the component (c) is, for example, 15 parts by mass or less, for example, 12 parts by mass or less, for example, 10 parts by mass or less, for example, 9 parts by mass or less, and for example, 7 parts by mass or less. Also, for example, 5 parts by mass or less, and for example, 3 parts by mass or less, and for example, 2 parts by mass or less, or 1 part by mass or less.
  • the preferable range of the content of the component (c) may be a combination of the upper limit and the lower limit thereof, but is, for example, 0.1 part by mass or more and 15 parts by mass or less, and for example, 0.1 part by mass or more and 10 parts by mass.
  • Parts or less for example 0.2 parts by mass or more and 9 parts by mass or less, and for example 0.2 parts by mass or more and 7 parts by mass or less, and for example 0.2 parts by mass or more and 5 parts by mass or less, Further, it is, for example, 0.2 parts by mass or more and 2 parts by mass or less, and for example, 0.2 parts by mass or more and 1 part by mass or less.
  • the present polymer may have a cross-linking structural unit other than the component (c).
  • the cross-linking structural unit is derived from a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups and a monomer having a self-crosslinkable crosslinkable functional group such as a hydrolyzable silyl group. The unit is mentioned.
  • the polyfunctional polymerizable monomer is a compound having two or more polymerizable functional groups such as a (meth) acryloyl group and an alkenyl group in the molecule, and is a polyfunctional (meth) acrylate compound, a polyfunctional alkenyl compound, (meth ) Examples thereof include compounds having both an acryloyl group and an alkenyl group. These compounds may be used alone or in combination of two or more.
  • polyfunctional (meth) acrylate compound examples include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di ( Di (meth) acrylates of dihydric alcohols such as (meth) acrylate; trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tetra ( Poly (meth) acrylates such as tri (meth) acrylates of trihydric or higher polyhydric alcohols such as (meth) acrylates, tetra (meth) acrylates; methylenebisacrylamide, hydro Shi ethylene bisacrylamide bisamides such as and the like.
  • polyfunctional alkenyl compound examples include trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, polyallyl saccharose and the like; diallyl phthalate and the like.
  • polyfunctional allyl compound examples include a polyfunctional vinyl compound such as divinylbenzene.
  • Examples of the compound having both a (meth) acryloyl group and an alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, and (meth) acrylic acid.
  • 2- (2-vinyloxyethoxy) ethyl and the like can be mentioned.
  • the monomer having a crosslinkable functional group capable of self-crosslinking include hydrolyzable silyl group-containing vinyl monomer, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate and the like. Is mentioned. These compounds may be used alone or in combination of two or more.
  • the hydrolyzable silyl group-containing vinyl monomer is not particularly limited as long as it is a vinyl monomer having at least one hydrolyzable silyl group.
  • vinyl silanes such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl methyl dimethoxy silane, vinyl dimethyl methoxy silane; silyl triacrylate such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylate, etc.
  • silyl group-containing acrylic acid esters trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate, etc.
  • silyl group-containing methacrylates trimethoxysilylpropyl vinyl ether, etc.
  • silyl group-containing vinyl ethers include silyl group-containing vinyl esters such as trimethoxysilyl vinyl undecanoate.
  • the cross-linking structural unit other than the component (c) is not particularly limited, but is, for example, 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the total amount of the non-crosslinking monomers. Can be prepared.
  • the structural unit may be 0.2 parts by mass, 3.0 parts by mass or less, 0.3 parts by mass, 2.0 parts by mass or less, 0.5 parts by mass, 1.0 part by mass. It may be less than or equal to parts by mass.
  • ⁇ Neutralization degree> In the present polymer, acid groups such as a carboxy group derived from an ethylenically unsaturated carboxylic acid monomer are neutralized so that the degree of neutralization in the composition is 20 to 100 mol%, and a salt form is obtained. It is preferable to use as.
  • the above-mentioned degree of neutralization is more preferably 50 to 100 mol%, for example 60 mol% or more, also for example 65 mol% or more, for example 70 mol% or more, for example 75 mol% or more, for example 80 mol% or more. And, for example, 85 mol% or more, also 90 mol% or more, and for example 95 mol% or more.
  • the degree of neutralization is 50 mol% or more, the water swelling property is good and the dispersion stabilizing effect is easily obtained, which is preferable.
  • the degree of neutralization can be calculated from the charged values of the monomer having an acid group such as a carboxy group and the neutralizing agent used for neutralization.
  • the degree of neutralization was determined by IR measurement of the powder obtained by drying the present polymer at 80 ° C. for 3 hours under reduced pressure, and the peak derived from the C ⁇ O group of the carboxylic acid and the C ⁇ O group of the carboxylate. It can be confirmed from the intensity ratio of the peak.
  • the present polymer which is a binder component of the present binder, can be produced by the following preparation step (polymerization step).
  • the method for producing the present polymer described below can also be carried out as a method for producing the present binder.
  • the preparation step is a step of preparing the present polymer. This is a step of obtaining the present polymer or obtaining the present polymer by polymerization (polymerization step).
  • the polymerization step is a step of polymerizing a monomer composition containing at least the non-crosslinkable monomer from which the component (a) is derived and the crosslinkable monomer from which the component (c) is derived. Is.
  • ⁇ Polymerization process> ⁇ Polymerization method>
  • known polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, and emulsion polymerization can be used, but from the viewpoint of productivity, precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) ) Is preferred.
  • a heterogeneous polymerization method such as precipitation polymerization, suspension polymerization, or emulsion polymerization is preferable, and among them, polymer fine particles having a small particle size excellent in uniformity are obtained.
  • the precipitation polymerization method is more preferable because it is easy.
  • Precipitation polymerization is a method of producing a polymer by carrying out a polymerization reaction in a solvent that dissolves an unsaturated monomer that is a raw material but does not substantially dissolve a produced polymer.
  • the polymer particles become larger due to aggregation and growth, and a dispersion liquid of polymer particles in which primary particles of several tens nm to several hundreds nm are secondarily aggregated to several ⁇ m to several tens ⁇ m is obtained.
  • Dispersion stabilizers can also be used to control the particle size of the polymer.
  • the secondary aggregation can be suppressed by selecting a dispersion stabilizer or a polymerization solvent.
  • precipitation polymerization in which secondary aggregation is suppressed is also called dispersion polymerization.
  • a solvent selected from water, various organic solvents, and the like can be used as the polymerization solvent in consideration of the type of monomer to be used. In order to obtain a polymer having a longer primary chain length, it is preferable to use a solvent having a small chain transfer constant.
  • Specific polymerization solvents include water-soluble solvents such as methanol, t-butyl alcohol, acetone, methyl ethyl ketone, acetonitrile and tetrahydrofuran, as well as benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane and n-heptane. These can be used alone or in combination of two or more. Alternatively, they may be used as a mixed solvent of these and water.
  • the water-soluble solvent refers to a solvent having a solubility in water at 20 ° C of more than 10 g / 100 ml.
  • Methyl ethyl ketone and acetonitrile are preferable in that they are easy), a polymer having a small chain transfer constant and a large degree of polymerization (primary chain length) can be obtained, and that the operation is easy at the time of the step neutralization described later. ..
  • a highly polar solvent water and methanol are preferably mentioned.
  • the amount of the highly polar solvent used is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and further preferably 0.1 to 1 based on the total mass of the medium. It is 0.0 mass%. When the proportion of the highly polar solvent is 0.05% by mass or more, the effect on the neutralization reaction is recognized, and when it is 10.0% by mass or less, no adverse effect on the polymerization reaction is observed.
  • the amount of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived is 10% by mass or more and 100% by mass or less, and ( b) A monomer containing 0% by mass or more and 90% by mass or less of another ethylenically unsaturated monomer from which the component is derived, and a non-crosslinkable monomer from the crosslinkable monomer from which the component (c) is derived.
  • a polymerization step of polymerizing a monomer composition containing 0.01 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the monomer By the polymerization step, the component (a) is introduced into the present polymer in an amount of 10% by mass or more and 100% by mass or less, and the component (b) is 0% by mass or more and 90% by mass or less with respect to the non-crosslinked structural unit. be introduced.
  • the amount of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived and the amount of the other ethylenically unsaturated monomer from which the component (b) is derived are the same as those described above with respect to the content of the non-crosslinked structural unit. It is appropriately set to correspond. Further, the amount of the crosslinkable monomer from which the component (c) is derived is also appropriately set so as to correspond to the content of the component (c) already described.
  • the ethylenically unsaturated carboxylic acid monomer may be in a non-neutralized state, or may be in a salt state in which at least a part thereof is neutralized.
  • the degree of neutralization of the ethylenically unsaturated carboxylic acid monomer is, for example, 10 mol% or less, and for example, 5 mol% or less, and it is preferably unneutralized. ..
  • such a monomer composition is a composition suitable for producing a binder for secondary battery electrodes.
  • the total concentration of monomers in the polymerization step may be, for example, 2.0% by mass or more, for example 4.0% by mass or more, and for example 10.0% by mass or more, but from the viewpoint of binding property. Preferably, it is, for example, 10.0 mass% or more, and for example, 13.0 mass% or more.
  • the monomer concentration is more preferably 15.0% by mass or more, further preferably 17.0% by mass or more, and further preferably 19.0% by mass or more.
  • the monomer concentration is more preferably 20.0% by mass or more, even more preferably 22.0% by mass or more, and even more preferably 25.0% by mass or more.
  • the higher the monomer concentration at the time of polymerization the higher the molecular weight can be made, and the polymer having a long primary chain length can be produced.
  • the present polymer is a finely crosslinked polymer obtained by appropriately crosslinking a polymer having a sufficiently long primary chain length, it is analytically difficult to directly measure the primary chain length. It is generally known that the primary chain length of a polymer correlates with the solution viscosity, but in the case of the present polymer, the solution viscosity also varies depending on the degree of crosslinking. Therefore, it is very difficult to define the present polymer obtained by the above method by the structure or characteristics of the present polymer.
  • the “monomer concentration” refers to the monomer concentration in the reaction liquid at the time of starting the polymerization.
  • the upper limit of the monomer concentration varies depending on the type of the monomer and the solvent used, the polymerization method, various polymerization conditions, etc., but if the heat of the polymerization reaction can be removed, it is about 40 mass in the precipitation polymerization. %, About 50% by mass in suspension polymerization, and about 70% by mass in emulsion polymerization.
  • the polymerization step may be carried out in the presence of a basic compound.
  • the binder containing the present polymer thus obtained can exhibit high binding properties.
  • the polymerization stability is improved, and even when the monomer concentration is high, the main composition The coalesced product can be manufactured stably.
  • the polymerization reaction By performing the polymerization reaction in the presence of a base compound, the polymerization reaction can be stably performed even under a high monomer concentration condition of, for example, more than 13.0 mass%.
  • a polymer obtained by polymerizing at such a high monomer concentration has a high molecular weight (because of its long primary chain length) and is therefore excellent in binding property.
  • the basic compound is a so-called alkaline compound, and either an inorganic basic compound or an organic basic compound may be used.
  • the inorganic base compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, alkali metals such as sodium carbonate and potassium carbonate.
  • alkali metal hydrogencarbonates such as metal carbonates, sodium hydrogencarbonate and potassium hydrogencarbonate.
  • organic base compound in addition to ammonia, for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monobutylamine, dibutylamine, tributylamine, monohexylamine, dihexylamine, trihexylamine, trioctylamine.
  • N-alkyl-substituted amines such as tridodecylamine; (ethyl) alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine and N, N-dimethylethanolamine; pyridine, piperidine, piperazine, Cyclic amines such as 1,8-bis (dimethylamino) naphthalene, morpholine and diazabicycloundecene (DBU); diethylene tria Emissions, N, N-organic amine compounds such as dimethylbenzylamine, and the like, may be used alone or two or more of these. Among these, organic amine compounds excluding ammonia are preferable from the viewpoint of binding property.
  • a base compound When a base compound is used in the polymerization step, it is preferable to use 0.001 mol% or more of the base compound with respect to the ethylenically unsaturated carboxylic acid monomer.
  • the amount of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, still more preferably 0.05 mol% or more. is there.
  • the amount of the base compound used may be 0.3 mol% or more, or may be 0.5 mol% or more. Further, the upper limit of the amount of the basic compound used is preferably 4.0 mol% or less. By carrying out the polymerization reaction in the presence of a base compound in an amount of 4.0 mol% or less, the polymerization stability can be improved, and the polymerization reaction proceeds smoothly even under a high monomer concentration condition.
  • the amount of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer is preferably 3.0 mol% or less, more preferably 2.0 mol% or less, further preferably 1.0 mol% or less. is there.
  • the amount of the base compound used represents the molar concentration of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer, and does not mean the degree of neutralization. That is, the valence of the basic compound used is not considered.
  • polymerization initiator known polymerization initiators such as azo compounds, organic peroxides and inorganic peroxides can be used, but are not particularly limited.
  • the use conditions can be adjusted by a known method such as thermal initiation, redox initiation using a reducing agent in combination, UV initiation, etc., so that an appropriate amount of radicals is generated.
  • thermal initiation thermal initiation
  • redox initiation using a reducing agent in combination
  • UV initiation etc.
  • azo compounds examples include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (N-butyl-2-methylpropionamide), 2- (tert-butylazo) -2. -Cyanopropane, 2,2'-azobis (2,4,4-trimethylpentane), 2,2'-azobis (2-methylpropane), etc., and one or more of them are used. be able to.
  • organic peroxide examples include 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (trade name “Pertetra A” manufactured by NOF CORPORATION), 1,1-di (t- Hexylperoxy) cyclohexane (the same “Perhexa HC”), 1,1-di (t-butylperoxy) cyclohexane (the same “Perhexa C”), n-butyl-4,4-di (t-butylperoxy) Valerate (the same "Perhexa V"), 2,2-di (t-butylperoxy) butane (the same "Perhexa 22"), t-butyl hydroperoxide (the same "Perbutyl H"), cumene hydroperoxide (Japan Oil company, trade name "Park Mill H”), 1,1,3,3-tetramethylbutyl hydroperoxide (the same "Per octa H”), t-
  • inorganic peroxide examples include potassium persulfate, sodium persulfate, ammonium persulfate and the like.
  • sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, sulfurous acid gas (SO 2 ), ferrous sulfate, etc. can be used as a reducing agent.
  • the preferred amount of the polymerization initiator used is, for example, 0.001 to 2 parts by mass, or 0.005 to 1 part by mass, when the total amount of the monomers used is 100 parts by mass. For example, it is 0.01 to 0.1 part by mass.
  • the amount of the polymerization initiator used is 0.001 part by mass or more, the polymerization reaction can be stably carried out, and when it is 2 parts by mass or less, a polymer having a long primary chain length can be easily obtained.
  • the polymerization temperature is preferably 0 to 100 ° C., more preferably 20 to 80 ° C., though it depends on conditions such as the type and concentration of the monomer used.
  • the polymerization temperature may be constant or may change during the period of the polymerization reaction.
  • the polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
  • a solid-liquid separation step such as centrifugation and filtration, water, methanol, acetonitrile or polymerization. It is preferable to include a washing step using the same solvent as the solvent.
  • ⁇ Neutralization process> when an unneutralized or partially neutralized salt is used as the ethylenically unsaturated carboxylic acid monomer, an alkaline compound is added to the polymer dispersion obtained by the polymerization step to neutralize the polymer.
  • step neutralization the solvent may be removed in the above-mentioned drying step to obtain the solid state polymer.
  • the drying step is carried out in the unneutralized or partially neutralized salt state to obtain a solid state main polymer such as powder, an alkali for forming a salt when preparing the electrode mixture layer slurry.
  • a step of adding a compound to neutralize the polymer hereinafter, also referred to as “post-neutralization” may be carried out.
  • post-neutralization the step neutralization is preferable because the secondary aggregate tends to be easily loosened.
  • the alkaline compound that can be used in the neutralization step such as the step neutralization is not particularly limited, but various alkaline compounds that can be used in the polymerization step described above can be used.
  • various alkaline compounds that can be used in the polymerization step described above can be used.
  • LiOH, NaOH, KOH, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like can be mentioned. From the viewpoint of battery performance when a Li salt is used, LiOH is preferable because it gives the Li salt of the present polymer.
  • the composition is a composition for an electrode (mixture layer) of a secondary battery, and can contain a binder containing the polymer, an active material, and water.
  • the amount of the present polymer used in the present composition is, for example, 0.1% by mass or more and 20% by mass or less based on the total amount of the active material.
  • the amount used is, for example, 0.2% by mass or more and 10% by mass or less, for example 0.3% by mass or more and 8% by mass or less, and for example 0.4% by mass or more and 5% by mass or less. .
  • the amount of the present polymer and its salt used is less than 0.1% by mass, sufficient binding property may not be obtained.
  • the dispersion stability of the active material and the like becomes insufficient, which may reduce the uniformity of the formed mixture layer.
  • the amount of the present polymer and its salt used exceeds 20% by mass, the composition of the electrode mixture layer may have a high viscosity and the coatability on the current collector may be deteriorated. As a result, the obtained mixture layer may have bumps or irregularities, which may adversely affect the electrode characteristics.
  • the present specification also provides a method for producing a composition for a secondary battery electrode, which comprises a step of preparing the present polymer and a step of preparing the present composition using the present polymer.
  • the present composition having a sufficiently low slurry viscosity can be obtained, and the adhesiveness to the current collector and thus the binding property of the mixture layer are extremely high.
  • the agent layer can be obtained, and as a result, the durability of the battery is improved.
  • the present polymer and its salt exhibit a sufficiently high binding property with respect to the active material even in a small amount (for example, 5% by mass or less), and since they have a carboxy anion, they have low interfacial resistance and excellent high rate characteristics.
  • the electrode is obtained.
  • a lithium salt of a transition metal oxide is mainly used as the positive electrode active material, and for example, layered rock salt type and spinel type lithium-containing metal oxides can be used.
  • the spinel-type positive electrode active material include lithium manganate.
  • phosphates, silicates, sulfur, and the like are used.
  • phosphates include olivine-type lithium iron phosphate.
  • the positive electrode active material one of the above may be used alone, or two or more of them may be used in combination as a mixture or composite.
  • the positive electrode active materials Since all positive electrode active materials have low electrical conductivity, they are generally used with a conductive additive added.
  • the conductive aid include carbon-based materials such as carbon black, carbon nanotubes, carbon fibers, graphite fine powder, and carbon fibers. Among them, carbon black, carbon nanotubes, and carbon fibers are easy to obtain excellent conductivity. , Are preferred.
  • the carbon black Ketjen black and acetylene black are preferable.
  • the conductive auxiliary agent one type described above may be used alone, or two or more types may be used in combination. The amount of the conductive auxiliary agent used can be, for example, 0.2 to 20% by mass based on the total amount of the active material from the viewpoint of achieving both conductivity and energy density. It can be mass%.
  • the positive electrode active material a surface-coated carbon-based material having conductivity may be used.
  • examples of the negative electrode active material include carbon-based materials, lithium metals, lithium alloys, metal oxides, and the like, and one or more of these may be used in combination.
  • active materials composed of carbon-based materials such as natural graphite, artificial graphite, hard carbon and soft carbon (hereinafter, also referred to as “carbon-based active material”) are preferable, and graphite such as natural graphite and artificial graphite, and Hard carbon is more preferred.
  • graphite spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferable particle size range is, for example, 1 to 20 ⁇ m and, for example, 5 to 15 ⁇ m.
  • a metal or metal oxide capable of occluding lithium such as silicon or tin can be used as the negative electrode active material.
  • silicon has a higher capacity than graphite, and active materials made of silicon-based materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter, also referred to as “silicon-based active material”).
  • silicon-based active material has a high capacity, but on the other hand, the volume change due to charge and discharge is large. Therefore, it is preferable to use the carbon-based active material together.
  • the amount of the silicon-based active material added is large, the electrode material may be collapsed, and the cycle characteristics (durability) may be significantly reduced. From such a point of view, when the silicon-based active material is used in combination, the amount thereof is, for example, 60% by mass or less, and for example, 30% by mass or less, based on the carbon-based active material.
  • the binder containing the present polymer has a structural unit (component (a)) in which the present polymer is derived from an ethylenically unsaturated carboxylic acid monomer.
  • component (a) has a high affinity for the silicon-based active material and exhibits a good binding property. Therefore, the present binder exhibits excellent binding properties even when a high-capacity type active material containing a silicon-based active material is used, and thus is also effective for improving the durability of the obtained electrode. Conceivable.
  • the carbon-based active material itself has good electrical conductivity, it is not always necessary to add a conductive auxiliary agent.
  • a conductive auxiliary agent is added for the purpose of further reducing resistance, the amount used is, for example, 10% by mass or less and 5% by weight or less, based on the total amount of the active material, from the viewpoint of energy density. Is.
  • the amount of the active material used is in the range of, for example, 10 to 75% by mass, or in the range of 30 to 65% by mass, based on the total amount of the composition.
  • the amount of the active material used is 10% by mass or more, migration of the binder and the like can be suppressed, and it is also advantageous in terms of medium drying cost.
  • the content is 75% by mass or less, the fluidity and coatability of the composition can be secured, and a uniform mixture layer can be formed.
  • the amount of the active material used is in the range of, for example, 60 to 97% by mass, or 70 to 90% by mass, based on the total amount of the present composition. It is a range. From the viewpoint of energy density, it is preferable that the amount of non-volatile components other than the active material such as the binder and the conductive additive be as small as possible within the range in which the required binding property and conductivity are ensured.
  • the composition uses water as a medium.
  • lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, water-soluble organic compounds such as tetrahydrofuran and N-methylpyrrolidone.
  • It may be a mixed solvent with a solvent.
  • the proportion of water in the mixed medium is, for example, 50% by mass or more and, for example, 70% by mass or more.
  • the content of the medium containing water in the entire composition is the coatability of the slurry, and the energy cost required for drying, from the viewpoint of productivity, for example,
  • the amount can be in the range of 25 to 90% by mass, and can be, for example, 35 to 70% by mass.
  • the content of the medium can be, for example, in the range of 3 to 40% by mass from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of up to 30% by mass.
  • the binder component contained in the composition may be composed only of the polymer, but in addition to this, a styrene / butadiene latex (SBR), an acrylic latex, a polyvinylidene fluoride latex, or the like. You may use together other binder components.
  • the other binder component is used in combination, the amount thereof can be, for example, 0.1 to 5% by mass or less, and for example, 0.1 to 2% by mass or less, based on the active material. And can be, for example, 0.1 to 1% by mass or less. If the amount of the other binder component used exceeds 5% by mass, the resistance may increase and the high rate property may become insufficient.
  • a styrene / butadiene-based latex is preferable because it has an excellent balance of binding property and flex resistance.
  • the present composition has the above-mentioned active material, water and binder as essential constituent components, and can be obtained by mixing the components using a known means.
  • the mixing method of each component is not particularly limited, and a known method can be adopted. After dry blending the powder components such as the active material, the conductive auxiliary agent and the polymer as a binder, water, etc.
  • the method of mixing with the dispersion medium of (1) and dispersing and kneading is preferable.
  • the present composition is obtained in the form of a slurry, it is preferable to finish it into a slurry free from poor dispersion and aggregation.
  • a known mixer such as a planetary mixer, a thin film swirling mixer and a revolving mixer can be used, but a thin film swirling mixer is used in that a good dispersion state can be obtained in a short time. It is preferable to carry out.
  • a thin film swirling mixer it is preferable to carry out preliminary dispersion with a stirrer such as a disper in advance.
  • the viscosity of the slurry of the present composition can be in the range of, for example, 500 to 100,000 mPa ⁇ s as a shear viscosity at a shear rate of 60 s ⁇ 1 at 25 ° C., and can be, for example, 1,000 to 50,000 mPa ⁇ s. It can be in the range of s. Further, for example, the slurry viscosity of the present composition is preferably in the range of 500 to 10,000 mPa ⁇ s, more preferably 500 to 7,000 mPa ⁇ s, and further preferably 500 to 6,000 mPa ⁇ s.
  • s more preferably 500 to 5,000 mPa ⁇ s, still more preferably 500 to 4,000 mPa ⁇ s, still more preferably 500 to 3,000 mPa ⁇ s. .S, more preferably 500 to 2,000 mPas, still more preferably 500 to 1,800 mPas, and still more preferably 500 to 1,700 mPas. s, preferably 500 to 1,600 mPa ⁇ s, and more preferably 500 to 1,500 m. It is a ⁇ s.
  • composition when the composition is obtained in a wet powder state, it is preferable to use a Henschel mixer, a blender, a planetary mixer, a twin-screw kneader or the like to knead the mixture to a uniform state without unevenness in concentration.
  • the present electrode comprises a mixture layer formed of the present composition on the surface of a current collector such as copper or aluminum.
  • the mixture layer is formed by applying the present composition on the surface of the current collector and then removing a medium such as water by drying.
  • the method of applying the present composition is not particularly limited, and a known method such as a doctor blade method, a dip method, a roll coating method, a comma coating method, a curtain coating method, a gravure coating method and an extrusion method may be adopted. it can.
  • the drying can be performed by a known method such as blowing hot air, reducing pressure, (far) infrared rays, or microwave irradiation.
  • the mixture layer obtained after drying is subjected to compression treatment by a die press, a roll press or the like.
  • compression treatment By compressing, the active material and the binder can be brought into close contact, and the strength of the mixture layer and the adhesion to the current collector can be improved.
  • the thickness of the mixture layer can be adjusted to, for example, about 30 to 80% before compression by compression, and the thickness of the mixture layer after compression is generally about 4 to 200 ⁇ m.
  • the present invention includes a step of preparing the present polymer, a step of preparing the present composition using the present polymer, and a step of preparing a secondary battery electrode using the present composition.
  • a method for manufacturing a secondary battery electrode is also provided.
  • a secondary battery By providing this electrode with a separator and a non-aqueous electrolyte, a secondary battery can be manufactured.
  • the separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of preventing a short circuit due to contact between both electrodes and holding an electrolytic solution to ensure ionic conductivity.
  • the separator is preferably a film-like insulating microporous film having good ion permeability and mechanical strength.
  • polyolefin such as polyethylene and polypropylene, polytetrafluoroethylene, or the like can be used.
  • non-aqueous electrolyte a known one generally used for secondary batteries can be used.
  • Specific solvents include cyclic carbonates having high permittivity and high electrolyte dissolving ability such as propylene carbonate and ethylene carbonate, and low-viscosity chain carbonates such as ethylmethyl carbonate, dimethyl carbonate and diethyl carbonate. , And these can be used alone or as a mixed solvent.
  • the non-aqueous electrolytic solution is used by dissolving a lithium salt such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , and LiAlO 4 in these solvents.
  • the secondary battery is obtained by accommodating a positive electrode plate and a negative electrode plate, which are partitioned by a separator, in a spiral or laminated structure in a case or the like.
  • the binder for secondary battery electrodes disclosed in the present specification can achieve both excellent binding properties and reduction in viscosity of the mixture layer slurry.
  • a secondary battery provided with an electrode obtained by using the above binder is expected to be able to secure good integrity and to exhibit good durability (cycle characteristics) even after repeated charge and discharge. It is suitable for secondary batteries and the like.
  • ⁇ Production Example of the Polymer> Production of crosslinked polymer salt R-1>
  • AA acrylic acid
  • the polymerization reaction was continued while adjusting the external temperature (water bath temperature) to maintain the internal temperature at 55 ° C, and the internal temperature was raised to 65 ° C when 6 hours passed from the polymerization initiation point.
  • the internal temperature was maintained at 65 ° C., cooling of the reaction solution was started 12 hours after the reaction start point, and after the internal temperature dropped to 25 ° C., lithium hydroxide monohydrate (hereinafter, referred to as “LiOH - 52.5 parts powder of H 2 O "hereinafter) was added.
  • stirring was continued for 12 hours at room temperature to obtain a slurry-like polymerization reaction liquid in which particles of the crosslinked polymer salt R-1 (Li salt, neutralization degree: 90 mol%) were dispersed in a medium.
  • the obtained polymerization reaction liquid was centrifuged to precipitate polymer particles, and the supernatant was removed. After that, the procedure of redispersing the precipitate in the same weight of acetonitrile as the polymerization reaction solution and then allowing the polymer particles to settle by centrifugation and removing the supernatant was repeated twice.
  • the precipitate was recovered and dried under reduced pressure at 80 ° C. for 3 hours to remove volatile matter, thereby obtaining a powder of crosslinked polymer salt R-1. Since the cross-linked polymer salt R-1 has a hygroscopic property, it was sealed and stored in a container having a water vapor barrier property.
  • the powder of the crosslinked polymer salt R-1 was subjected to IR measurement, and the degree of neutralization was determined from the intensity ratio of the peak derived from the C ⁇ O group of the carboxylic acid and the peak derived from the C ⁇ O of the carboxylic acid Li. 90 mol% equal to the value calculated from
  • AA acrylic acid
  • HAPMA 2-hydroxy-3-acryloyloxypropyl methacrylate (light ester G-201P, Kyoeisha Chemical Co., Ltd.)
  • GDMA glycerin dimethacrylate (light ester G-101P, Kyoeisha Chemical)
  • EGDMA Ethylene dimethacrylate (Fuji Film Wako Pure Chemical)
  • T-20 Trimethylolpropane diallyl ether (Osaka Soda)
  • TEA triethylamine
  • AcCN acetonitrile
  • V-65 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)
  • Example> ⁇ Example 1> 3.2 parts of powdered cross-linked polymer Li salt R-1 was weighed in 100 parts of natural graphite, mixed well in advance, 160 parts of ion-exchanged water was added and predispersed with a disper, and then thin film rotation type The main dispersion was performed for 15 seconds at a peripheral speed of 20 m / sec using a mixer (FM-56-30, manufactured by Primix Co., Ltd.) to obtain a slurry negative electrode mixture layer composition. The slurry concentration (solid content) was calculated to be 39.2%.
  • ⁇ Viscosity measurement of electrode slurry The negative electrode mixture layer composition (slurry) obtained above was measured at 25 ° C. using a cone plate (diameter 25 mm, cone angle 5 °) of CP25-5 using an Anton Paar Rheometer (Physica MCR301). The slurry viscosity at a shear rate of 60 s -1 was measured.
  • the mixture layer composition was applied onto a copper foil (manufactured by Nippon Foil Co., Ltd.) having a thickness of 20 ⁇ m, and dried at 100 ° C. for 15 minutes in a ventilation dryer to form a mixture layer. Formed. Then, the mixture layer was rolled to a thickness of 70 ⁇ 5 ⁇ m and a packing density of 1.70 ⁇ 0.20 g / cm 3 to prepare a negative electrode.
  • the negative electrode obtained above was cut into a strip having a width of 25 mm, and the mixture layer surface of the above sample was attached to a double-sided tape fixed on a horizontal surface to prepare a peel test sample.
  • Examples 2 to 15, Comparative Examples 1 to 3> A negative electrode mixture layer composition was prepared in the same manner as in Example 1, except that the crosslinked polymer salt used as the active material and the binder was used as described in Table 2.
  • examples 3 and 4 natural graphite and silicon particles were stirred for 1 hour at 400 rpm using a planetary ball mill (P-5, manufactured by FRITSCH), and the obtained mixture was crosslinked into powder form.
  • 3.2 parts of Li salt R-2 was weighed and thoroughly mixed in advance, and then the same operation as in Example 1 was performed to prepare a mixture layer composition. The slurry viscosity and 90 ° peel strength of each mixture layer composition were evaluated. The results are shown in Table 2.
  • Examples 1 to 15 using cross-linked polymers R-1 to R-13 using a cross-linkable monomer having two or more (meth) acryloyl groups and a hydroxyl group were combined.
  • the viscosity of the agent layer slurry was 330 to 1800 mPa ⁇ s, showing extremely good viscosity.
  • the peel strengths of Examples 1 to 15 were 14.4 to 19.1 N / m, which showed sufficient electrode binding property.
  • Comparative Example 1 using the polymer of Production Example 14 which was not crosslinked a crosslinkable monomer having high viscosity but low binding property and having two acryloyl groups but no hydroxyl group was used.
  • Comparative Example 2 using the crosslinked polymer of Production Example 15 used, the binding property was good, but the slurry viscosity was still considerably high, and the crosslinkable monomer having two allyl groups and having a hydroxyl group was used.
  • Comparative Example 3 in which the crosslinked polymer of Production Example 16 using a body was used, the binding property was low and the slurry viscosity was still high.
  • the ethylenically unsaturated carboxylic acid monomer and the crosslinkable monomer having two (meth) acryloyl groups and having a hydroxyl group are polymerized to derive the crosslinkable monomer. It was found that by providing the crosslinked structure, good binding properties and slurry viscosity can both be achieved.
  • the amount of the crosslinkable monomer used was about 0.1 to 10 parts based on 100 parts of the non-crosslinkable monomer, and the binding property was good. It is possible to obtain a crosslinked polymer, and 0.2 parts to 9 parts, 0.2 parts to 5 parts, 0.2 parts to 2 parts, and 0.2 parts to 1 part are more suitable for forming crosslinks. It was found that a polymer could be obtained. It was also found that the amount of the crosslinkable monomer used was about 0.1 to 10 parts to obtain a crosslinked polymer having a sufficiently low slurry viscosity.

Abstract

In order to achieve both binding properties and the suppression of electrode slurry viscosity in secondary battery electrodes, a binder for secondary battery electrodes is provided. The binder has a crosslinked polymer or a salt thereof, and comprises a non-crosslinked structural unit and a crosslinked structural unit, wherein the non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated carboxylic acid monomer, and the crosslinked structural unit includes a crosslinked structural unit derived from a crosslinkable monomer which has two or more (meth)acryloyl groups in one molecule and has a hydroxyl group.

Description

二次電池電極用バインダー及びその利用Binder for secondary battery electrode and use thereof
　本明細書は二次電池電極用バインダー及びその利用に関する。
（関連出願の相互参照）
　本出願は、２０１８年１０月３１日に出願された日本国特許出願である特願２０１８－２０５２２８の関連出願であり、この日本出願に基づく優先権を主張するものであり、その全内容は、引用により、本明細書に組み込まれるものとする。 The present specification relates to a binder for a secondary battery electrode and its use.
(Cross-reference of related applications)
This application is a related application of Japanese Patent Application No. 2018-205228 filed on Oct. 31, 2018, and claims the priority right based on this Japanese application. Incorporated herein by reference.
　二次電池として、ニッケル水素二次電池、リチウムイオン二次電池、電気二重層キャパシタ等の様々な蓄電デバイスが実用化されている。これらの二次電池に使用される電極は、活物質及びバインダー等を含む電極合剤層を形成するための組成物を集電体上に塗布・乾燥等することにより作製される。例えばリチウムイオン二次電池では、負極合剤層組成物に用いられるバインダーとして、スチレンブタジエンゴム（ＳＢＲ）ラテックス及びカルボキシメチルセルロース（ＣＭＣ）を含む水系のバインダーが使用されている。 As a secondary battery, various storage devices such as nickel-hydrogen secondary battery, lithium-ion secondary battery, and electric double layer capacitor have been put to practical use. The electrodes used in these secondary batteries are produced by applying a composition for forming an electrode mixture layer containing an active material, a binder and the like onto a current collector and drying the composition. For example, in a lithium-ion secondary battery, an aqueous binder containing styrene-butadiene rubber (SBR) latex and carboxymethyl cellulose (CMC) is used as a binder used in the negative electrode mixture layer composition.
　一方、各種二次電池の用途が拡大するにつれて、エネルギー密度、信頼性及び耐久性向上への要求が強まる傾向にある。例えば、リチウムイオン二次電池の電気容量を高める目的で、負極用活物質としてシリコン系の活物質を用いる仕様が増えてきている。しかしながら、シリコン系活物質は充放電時の体積変化が大きいことが知られており、繰り返し使用するにつれて電極合剤層の剥離又は脱落等が生じ、その結果、電池の容量が低下し、サイクル特性（耐久性）が悪化するという問題があった。このような不具合を抑制するためには、一般的にはバインダーの結着性を高めることが有効であり、耐久性を改善する目的で、バインダーの結着性向上に関する検討が行われている。 On the other hand, as the use of various secondary batteries expands, demands for improving energy density, reliability and durability tend to increase. For example, specifications for using a silicon-based active material as the negative electrode active material are increasing in order to increase the electric capacity of the lithium-ion secondary battery. However, it is known that the volume change of a silicon-based active material during charge / discharge is large, and peeling or dropping of the electrode mixture layer occurs as it is repeatedly used, and as a result, the capacity of the battery decreases and the cycle characteristics There was a problem that (durability) deteriorates. In order to suppress such a problem, it is generally effective to enhance the binding property of the binder, and for the purpose of improving the durability, studies on improving the binding property of the binder have been conducted.
　良好な結着性を有し、耐久性向上への効果を奏するバインダーとして、上記アクリル酸系重合体を利用したバインダーが提案されている。特許文献１では、特定の架橋剤によりポリアクリル酸を架橋したポリマーを結着剤として用いることにより、シリコンを含む活物質を用いた場合であっても電極構造が破壊されることのない電極の提供が可能であることが記載されている。特許文献２には、カルボキシ基を有する架橋重合体又はその塩であって、中和後に塩水中に分散させた際の粒子径が十分小さい重合体を含むバインダーを用いて得られた電極が、優れた結着性を示すことが記載されている。 A binder using the above acrylic acid-based polymer has been proposed as a binder having good binding properties and an effect of improving durability. In Patent Document 1, by using a polymer obtained by crosslinking polyacrylic acid with a specific cross-linking agent as a binder, the electrode structure is not destroyed even when an active material containing silicon is used. It is described that it can be provided. Patent Document 2 discloses a crosslinked polymer having a carboxy group or a salt thereof, which is obtained by using a binder containing a polymer having a sufficiently small particle size when dispersed in salt water after neutralization, It is described that it exhibits excellent binding properties.
国際公開第２０１４／０６５４０７号International Publication No. 2014/065407 国際公開第２０１７／０７３５８９号International Publication No. 2017/073589
　各特許文献に開示されるバインダーは、いずれも良好な結着性を付与し得るものであるが、二次電池の性能向上に伴い、より一層結着性の高い電極合剤層が求められるようになっている。また、結着性を高めるためにバインダーを増量すると、電極合剤層組成物のスラリー粘度が高くなり、塗工性が低下してしまっていた。このため、スラリー粘度の低減が可能なバインダーが求められている。 The binders disclosed in each patent document are all capable of imparting good binding properties, but as the performance of the secondary battery is improved, an electrode mixture layer having higher binding properties is required. It has become. Further, when the amount of the binder is increased in order to improve the binding property, the slurry viscosity of the electrode mixture layer composition becomes high and the coatability is deteriorated. Therefore, there is a demand for a binder that can reduce the viscosity of the slurry.
　本明細書は、結着性の向上と電極合剤層用スラリーの粘度低下とを両立できるバインダー及びその利用を提供する。 The present specification provides a binder that can improve the binding property and reduce the viscosity of the slurry for the electrode mixture layer, and the use thereof.
　本発明者らは、スラリー粘度を増大させることなく結着性を向上させることについて、架橋性単量体に着目して種々検討した結果、ラジカル反応性の高い（メタ）アクリロイル基を２個以上有するとともに水酸基を有する架橋性単量体を用いた架橋重合体によれば、上記課題を解決できるという知見を得た。本明細書によれば、かかる知見に基づき以下の手段が提供される。 As a result of various studies focusing on the crosslinkable monomer for improving the binding property without increasing the slurry viscosity, the present inventors have found that two or more (meth) acryloyl groups having high radical reactivity are used. It was found that the above-mentioned problems can be solved by a crosslinked polymer using a crosslinkable monomer having a hydroxyl group. According to this specification, the following means are provided based on such knowledge.
［１］架橋重合体又はその塩を有する二次電池電極バインダーであって、
　前記架橋重合体又はその塩は、非架橋構造単位と架橋構造単位とを備え、
　前記非架橋構造単位は、エチレン性不飽和カルボン酸単量体に由来する非架橋構造単位を含み、
　前記架橋構造単位は、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体に由来する架橋構造単位を含む、
バインダー。
［２］前記エチレン性不飽和単量体に由来する非架橋構造単位を、前記非架橋構造単位の総量に対して３０質量％以上１００質量％以下含有する、［１］に記載のバインダー。
［３］二次電池電極用組成物であって、
　［１］又は［２］に記載の二次電池電極用バインダーと、
　活物質と、
　水と、
を含有する組成物。
［４］二次電池電極であって、
　［１］又は［２］に記載の二次電池電極用バインダーと、
　活物質と、
を含有する電極。
［５］さらに、前記活物質は、ケイ素含有物質である、［４］に記載の電極。
［６］二次電池電極用バインダーの製造方法であって、
　エチレン性不飽和カルボン酸単量体と、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体と、を含有する単量体組成物を重合する工程、
を有する、製造方法。 [1] A secondary battery electrode binder having a crosslinked polymer or a salt thereof, comprising:
The crosslinked polymer or a salt thereof comprises a non-crosslinked structural unit and a crosslinked structural unit,
The non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated carboxylic acid monomer,
The cross-linking structural unit has two or more (meth) acryloyl groups in one molecule, and includes a cross-linking structural unit derived from a cross-linkable monomer having a hydroxyl group,
binder.
[2] The binder according to [1], which contains the non-crosslinking structural unit derived from the ethylenically unsaturated monomer in an amount of 30% by mass or more and 100% by mass or less based on the total amount of the non-crosslinking structural unit.
[3] A composition for a secondary battery electrode, comprising:
A binder for a secondary battery electrode according to [1] or [2],
Active material,
water and,
A composition containing:
[4] A secondary battery electrode,
A binder for a secondary battery electrode according to [1] or [2],
Active material,
An electrode containing.
[5] The electrode according to [4], wherein the active material is a silicon-containing material.
[6] A method for manufacturing a binder for a secondary battery electrode, comprising:
Step of polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer and a crosslinkable monomer having two or more (meth) acryloyl groups in one molecule and having a hydroxyl group ,
And a manufacturing method.
　本明細書に開示される二次電池電極用バインダー（以下、単に、本バインダーともいう。）は、架橋重合体又はその塩（以下、単に、本重合体ともいう。）を含むことができる。本重合体は、非架橋構造単位と架橋構造単位とを備え、前記非架橋構造単位は、エチレン性不飽和単量体に由来する非架橋構造単位を含み、前記架橋構造単位は、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体に由来する架橋構造単位を含むことができる。 The secondary battery electrode binder (hereinafter, simply referred to as the binder) disclosed in the present specification can include a crosslinked polymer or a salt thereof (hereinafter, simply referred to as the present polymer). The present polymer comprises a non-crosslinked structural unit and a crosslinked structural unit, the non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated monomer, the crosslinked structural unit in one molecule Can have a crosslinked structural unit derived from a crosslinkable monomer having two or more (meth) acryloyl groups and having a hydroxyl group.
　本重合体は、非架橋構造単位に、カルボン酸を有するため、結着性の良好なバインダーとなる。また、本重合体は、架橋構造単位に、（メタ）アクリロイル基を２個以上有する架橋性単量体に由来する架橋構造単位を含む。このような架橋性単量体は、ラジカル重合性が比較的高いため、重合体粒子内部から表面部分にわたり比較的均一に架橋構造単位が形成される。換言すると、架橋重合によって得られる本重合体粒子表面の架橋密度が過度に高まることを抑制できると考えられ、その結果、水中での本重合体粒子表面の膨潤度が比較的高く、活物質や集電体との接着面積を確保でき、本重合体粒子を含むバインダーが良好な結着性を示すと考えられる。 Since this polymer has a carboxylic acid in the non-crosslinked structural unit, it becomes a binder with good binding properties. Further, the present polymer contains, in the cross-linking structural unit, a cross-linking structural unit derived from a cross-linking monomer having two or more (meth) acryloyl groups. Since such a crosslinkable monomer has a relatively high radical polymerizability, a crosslinked structural unit is formed relatively uniformly from the inside of the polymer particle to the surface portion. In other words, it is considered that the cross-linking density of the present polymer particle surface obtained by cross-linking polymerization can be suppressed from being excessively increased, and as a result, the degree of swelling of the present polymer particle surface in water is relatively high, and the active material or It is considered that the adhesive area with the current collector can be secured and the binder containing the present polymer particles exhibits good binding properties.
　また、本重合体は、架橋構造単位に、水酸基を有するため、重合体粒子内において水酸基による相互作用（水素結合等）により本重合体粒子の膨潤度を抑制して、スラリー粘度の上昇を抑制することができる。 Further, since the present polymer has a hydroxyl group in the cross-linking structural unit, the swelling degree of the present polymer particle is suppressed by the interaction (hydrogen bond etc.) due to the hydroxyl group in the polymer particle, and the increase of slurry viscosity is suppressed. can do.
　二次電池電極用組成物は、本バインダーを含むため、塗工容易性を備えたものとなる。また、本バインダーを含む二次電池電極は、優れた結着性を示す。また、本バインダーの製造方法、二次電池電極用組成物及び二次電池電極の製造方法によれば、電極用スラリー調製時における粘度上昇を抑制して結着性に優れる電極を提供することができる。 Since the secondary battery electrode composition contains the present binder, it is easy to apply. Moreover, the secondary battery electrode containing the present binder exhibits excellent binding properties. Further, according to the present binder production method, secondary battery electrode composition and secondary battery electrode production method, it is possible to provide an electrode having excellent binding properties by suppressing an increase in viscosity during preparation of the electrode slurry. it can.
　本バインダーは、本重合体を含有するものであり、活物質及び水と混合することにより二次電池電極用組成物（電極合剤層組成物、以下、単に、本組成物ともいう。）とすることができる。本組成物は、集電体への塗工が可能なスラリー状態であってもよいし、湿粉状態として調製し、集電体表面へのプレス加工に対応できるようにしてもよい。銅箔又はアルミニウム箔等の集電体表面に本組成物から形成される合剤層を形成することにより、本明細書に開示される二次電池電極（以下、単に、本電極ともいう。）が得られる。 The present binder contains the present polymer, and by mixing with an active material and water, a secondary battery electrode composition (electrode mixture layer composition, hereinafter, also simply referred to as the present composition). can do. The composition may be in a slurry state in which it can be applied to a current collector, or may be prepared in a wet powder state so that it can be pressed to the surface of the current collector. By forming a mixture layer formed of the present composition on the surface of a current collector such as copper foil or aluminum foil, the secondary battery electrode disclosed in the present specification (hereinafter, also simply referred to as the present electrode). Is obtained.
　以下、本バインダーほか、本組成物、本バインダーの製造方法、本組成物の製造方法及び本電極の製造方法等についての代表的かつ非限定的な具体例について、適宜図面を参照して詳細に説明する。この詳細な説明は、本開示の好ましい例を実施するための詳細を当業者に示すことを単純に意図しており、本開示の範囲を限定することを意図したものではない。また、以下に開示される追加的な特徴は、さらに改善された「二次電池電極用バインダー及びその利用」を提供するために、他の特徴や開示とは別に、又は共に用いることができる。 Hereinafter, other than the present binder, representative and non-limiting specific examples of the present composition, a method for producing the present binder, a method for producing the present composition, a method for producing the present electrode, etc. will be described in detail with reference to the drawings as appropriate. explain. This detailed description is merely intended to present those skilled in the art with details for implementing the preferred examples of the present disclosure and is not intended to limit the scope of the present disclosure. Also, the additional features disclosed below can be used separately from or together with other features or disclosures to provide a further improved "binder for secondary battery electrodes and use thereof".
　また、以下の詳細な説明で開示される特徴や工程の組み合わせは、最も広い意味において本開示を実施する際に必須のものではなく、特に本開示の代表的な具体例を説明するためにのみ記載されるものである。さらに、上記及び下記の代表的な具体例の様々な特徴、ならびに、独立及び従属クレームに記載されるものの様々な特徴は、本開示の追加的かつ有用な実施形態を提供するにあたって、ここに記載される具体例のとおりに、あるいは列挙された順番のとおりに組合せなければならないものではない。 Further, the combination of features and steps disclosed in the following detailed description is not essential in carrying out the present disclosure in the broadest sense, and is only for describing a representative specific example of the present disclosure. It is described. Furthermore, various features of the exemplary embodiments above and below, as well as those set forth in the independent and dependent claims, are described herein in providing additional and useful embodiments of the present disclosure. It is not necessary to combine them according to the specific examples described or in the order listed.
　本明細書及び／又はクレームに記載された全ての特徴は、実施例及び／又はクレームに記載された特徴の構成とは別に、出願当初の開示ならびにクレームされた特定事項に対する限定として、個別に、かつ互いに独立して開示されることを意図するものである。さらに、全ての数値範囲及びグループ又は集団に関する記載は、出願当初の開示ならびにクレームされた特定事項に対する限定として、それらの中間の構成を開示する意図を持ってなされている。 All the features described in the present specification and / or the claims are, apart from the configuration of the features described in the examples and / or the claims, individually as a limitation to the disclosure at the time of filing the application and specific matters claimed, And are intended to be disclosed independently of each other. Furthermore, all numerical ranges and statements regarding groups or groups are intended to disclose the disclosure as originally filed and as limitations on the specific matter claimed, as well as intermediate constructions thereof.
　尚、本明細書において、「（メタ）アクリル」とは、アクリル及び／又はメタクリルを意味し、「（メタ）アクリレート」とは、アクリレート及び／又はメタクリレートを意味する。また、「（メタ）アクリロイル基」とは、アクリロイル基及び／又はメタクリロイル基を意味する。 In the present specification, “(meth) acrylic” means acrylic and / or methacrylic, and “(meth) acrylate” means acrylate and / or methacrylate. Further, the “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.
＜バインダー＞
　本バインダーは、本重合体、すなわち、架橋重合体又はその塩を含むことができる。本バインダーは、本重合体のみを含んでいてもよいし、後述するように他のバインダー成分を含んでいてもよい。好ましくは、本重合体をバインダー成分の５０質量％以上含有し、また例えば６０質量％以上含有し、また例えば７０質量％以上含有し、また例えば８０質量％以上含有し、また例えば９０質量％以上含有し、また例えば９５質量％以上含有し、また例えば１００質量％含有する。 <Binder>
The binder may include the polymer, that is, a crosslinked polymer or a salt thereof. The present binder may contain only the present polymer, or may contain other binder components as described later. Preferably, the present polymer is contained in an amount of 50% by mass or more of the binder component, for example 60% by mass or more, for example 70% by mass or more, for example 80% by mass or more, and for example 90% by mass or more. It is contained, for example, 95% by mass or more, and for example, 100% by mass.
＜架橋重合体の構造単位＞
＜非架橋構造単位＞
　本重合体は、非架橋構造単位と架橋構造単位とを備えている。非架橋構造単位としては、特に限定しないで、二次電池電極のバインダーとして用いることのできる架橋重合体に用いることができる各種非架橋性単量体に由来する構造単位を非架橋構造単位として備えることができる。 <Structural unit of cross-linked polymer>
<Non-crosslinked structural unit>
The polymer has a non-crosslinked structural unit and a crosslinked structural unit. The non-crosslinking structural unit is not particularly limited, and includes structural units derived from various non-crosslinking monomers that can be used in the crosslinked polymer that can be used as the binder of the secondary battery electrode, as the noncrosslinking structural unit. be able to.
　非架橋構造単位としては、例えば、エチレン性不飽和カルボン酸単量体に由来する構造単位（以下、「（ａ）成分」ともいう。）を有することができる。カルボキシ基を構造単位に有することで、集電体への接着性が向上するとともに、リチウムイオンの脱溶媒和効果及びイオン伝導性に優れるため、抵抗が小さく、ハイレート特性に優れた電極が得られる。また、水膨潤性が付与されるため、本組成物中における活物質等の分散安定性を高めることができる。上記構造単位は、例えば、エチレン性不飽和カルボン酸単量体を含む単量体を重合することにより本重合体に導入することができる。その他にも、（メタ）アクリル酸エステル単量体を（共）重合した後、加水分解することによっても得られる。また、（メタ）アクリルアミド及び（メタ）アクリロニトリル等を重合した後、強アルカリで処理してもよいし、水酸基を有する本重合体に酸無水物を反応させる方法であってもよい。 The non-crosslinked structural unit may have, for example, a structural unit derived from an ethylenically unsaturated carboxylic acid monomer (hereinafter, also referred to as “component (a)”). By having a carboxy group in the structural unit, the adhesion to the current collector is improved, and since the lithium ion desolvation effect and the ionic conductivity are excellent, the resistance is small, and an electrode having excellent high rate characteristics can be obtained. .. Further, since water swelling property is imparted, dispersion stability of the active material and the like in the present composition can be enhanced. The above structural unit can be introduced into the present polymer by, for example, polymerizing a monomer containing an ethylenically unsaturated carboxylic acid monomer. Alternatively, it can also be obtained by (co) polymerizing a (meth) acrylic acid ester monomer and then hydrolyzing it. Moreover, after polymerizing (meth) acrylamide, (meth) acrylonitrile, etc., it may be treated with a strong alkali or a method of reacting an acid anhydride with the main polymer having a hydroxyl group.
　エチレン性不飽和カルボン酸単量体としては、（メタ）アクリル酸、イタコン酸、クロトン酸、マレイン酸、フマル酸；（メタ）アクリルアミドヘキサン酸及び（メタ）アクリルアミドドデカン酸等の（メタ）アクリルアミドアルキルカルボン酸；コハク酸モノヒドロキシエチル（メタ）アクリレート、ω－カルボキシ－カプロラクトンモノ（メタ）アクリレート、β－カルボキシエチル（メタ）アクリレート等のカルボキシ基を有するエチレン性不飽和単量体またはそれらの（部分）アルカリ中和物が挙げられ、これらの内の１種を単独で使用してもよいし、２種以上を組み合わせて使用してもよい。上記の中でも、重合速度が大きいために一次鎖長の長い重合体が得られ、バインダーの結着力が良好となる点で重合性官能基としてアクリロイル基を有する化合物が好ましく、特に好ましくはアクリル酸である。エチレン性不飽和カルボン酸単量体としてアクリル酸を用いた場合、カルボキシ基含有量の高い重合体を得ることができる。 Examples of the ethylenically unsaturated carboxylic acid monomer include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamidoalkyl acid such as (meth) acrylamidohexanoic acid and (meth) acrylamidododecanoic acid. Carboxylic acid; ethylenically unsaturated monomers having a carboxy group such as succinic acid monohydroxyethyl (meth) acrylate, ω-carboxy-caprolactone mono (meth) acrylate, β-carboxyethyl (meth) acrylate or the like (part thereof) ) Alkali-neutralized products are mentioned, and one of them may be used alone, or two or more thereof may be used in combination. Among the above, a polymer having a long primary chain length is obtained because of a high polymerization rate, and a compound having an acryloyl group as a polymerizable functional group is preferable in that the binding force of the binder is good, and acrylic acid is particularly preferable. is there. When acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer having a high carboxy group content can be obtained.
　エチレン性不飽和カルボン酸単量体のカルボキシ基に関してフリーであってもよいし少なくとも一部が塩であってもよい。塩の種類としては特に限定しないが、リチウム、ナトリウム、カリウム等のアルカリ金属塩；カルシウム塩及びバリウム塩等のアルカリ土類金属塩；マグネシウム塩、アルミニウム塩等のその他の金属塩；アンモニウム塩及び有機アミン塩等が挙げられる。これらの中でも電池特性への悪影響が生じにくい点からアルカリ金属塩及びマグネシウム塩が好ましく、アルカリ金属塩がより好ましい。特に好ましいアルカリ金属塩は、リチウム塩である。 The carboxy group of the ethylenically unsaturated carboxylic acid monomer may be free or at least a part thereof may be a salt. The type of salt is not particularly limited, but alkali metal salts such as lithium, sodium and potassium; alkaline earth metal salts such as calcium salt and barium salt; other metal salts such as magnesium salt and aluminum salt; ammonium salt and organic salt Examples thereof include amine salts. Among these, alkali metal salts and magnesium salts are preferable, and alkali metal salts are more preferable, because they are unlikely to adversely affect battery characteristics. A particularly preferred alkali metal salt is a lithium salt.

　本重合体における（ａ）成分の含有量は、特に限定するものではないが、例えば、本重合体の非架橋構造単位の総量に対して１０質量％以上、１００質量％以下含むことができる。かかる範囲で（ａ）成分を含有することで、集電体に対する優れた接着性を容易に確保することができる。下限は、例えば２０質量％以上であり、また例えば３０質量％以上であり、また例えば４０質量％以上である。下限は、５０質量％以上であってもよく、例えば、６０質量％以上であり、また例えば７０質量％以上であり、また例えば８０質量％以上である。３０質量％以上であると、集電体への接着性を確保でき、良好なリチウムイオンの脱溶媒和効果及びイオン伝導性を備えるため、ハイレート特性に優れた電極が得られる。また、水膨潤性により本組成物中における活物質等の分散安定性を高めることができる。（ａ）成分の含有量の増大により、こうした効果が向上する傾向がある。
The content of the component (a) in the present polymer is not particularly limited, but may be, for example, 10% by mass or more and 100% by mass or less based on the total amount of the non-crosslinked structural units of the present polymer. By containing the component (a) in such a range, excellent adhesiveness to the current collector can be easily ensured. The lower limit is, for example, 20% by mass or more, for example, 30% by mass or more, and for example, 40% by mass or more. The lower limit may be 50% by mass or more, for example 60% by mass or more, for example 70% by mass or more, and for example 80% by mass or more. When it is 30% by mass or more, the adhesiveness to the current collector can be secured, and a good lithium ion desolvation effect and ion conductivity are provided, so that an electrode having excellent high rate characteristics can be obtained. Further, the water swelling property can enhance the dispersion stability of the active material and the like in the present composition. Such an effect tends to be improved by increasing the content of the component (a).
　また、上限は、１００質量％であって、１００質量％も好適であり得るが、例えば、９９質量％以下であり、また例えば９８質量％以下であり、また例えば９５質量％以下であり、また例えば９０質量％以下である。 The upper limit is 100% by mass, and 100% by mass may be suitable, but is, for example, 99% by mass or less, for example 98% by mass or less, and for example 95% by mass or less, and For example, it is 90 mass% or less.
　（ａ）成分の範囲としては、こうした下限及び上限を適宜組み合わせた範囲とすることができるが、例えば、本重合体の非架橋構造単位の総量に対して１０質量％以上、１００質量％以下であり、また例えば２０質量％以上、１００質量％以下であり、また例えば３０質量％以上、１００質量％以下であり、また例えば５０質量％以上、１００質量％以下であり、また例えば６０質量％以上、１００質量％以下であり、また例えば７０質量％以上１００質量％以下などとすることができる。全構造単位に対する（ａ）成分の割合が１０質量％未満の場合、分散安定性、結着性及び電池としての耐久性が不足する場合があり得る。 The range of the component (a) can be a range in which the lower limit and the upper limit are appropriately combined. For example, the range is 10% by mass or more and 100% by mass or less based on the total amount of the non-crosslinked structural units of the present polymer. And 20 mass% or more and 100 mass% or less, or 30 mass% or more and 100 mass% or less, or 50 mass% or more and 100 mass% or less, and 60 mass% or more, for example. , 100% by mass or less, and may be, for example, 70% by mass or more and 100% by mass or less. When the ratio of the component (a) to the total structural units is less than 10% by mass, dispersion stability, binding property and durability as a battery may be insufficient.
　非架橋構造単位の総量に対する（ａ）成分の含有量は、例えば、本重合体に用いる非架橋性単量体の総量に対するエチレン性不飽和カルボン酸単量体の含有量としても取得できる。 The content of the component (a) with respect to the total amount of the non-crosslinking structural units can be obtained as, for example, the content of the ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinking monomer used in the present polymer.
＜その他の構造単位＞
　本重合体は、（ａ）成分以外に、これらと共重合可能な他のエチレン性不飽和単量体に由来する構造単位（以下、「（ｂ）成分」ともいう。）を含むことができる。（ｂ）成分としては、例えば、スルホン酸基及びリン酸基等のカルボキシ基以外のアニオン性基を有するエチレン性不飽和単量体化合物、または非イオン性のエチレン性不飽和単量体等に由来する構造単位が挙げられる。これらの構造単位は、スルホン酸基及びリン酸基等のカルボキシ基以外のアニオン性基を有するエチレン性不飽和単量体化合物、または非イオン性のエチレン性不飽和単量体を含む単量体を共重合することにより導入することができる。これらの内でも、（ｂ）成分としては、耐屈曲性良好な電極が得られる観点から非イオン性のエチレン性不飽和単量体に由来する構造単位が好ましく、バインダーの結着性やスラリー粘度が優れる点で（メタ）アクリルアミド及びその誘導体等が好ましい。また、（ｂ）成分として水中への溶解性が１ｇ／１００ｍｌ以下の疎水性のエチレン性不飽和単量体に由来する構造単位を導入した場合、電極材料と強い相互作用を奏することができ、活物質に対して良好な結着性を発揮することができる。これにより、堅固で一体性の良好な電極合剤層を得ることができるため好ましい。特に脂環構造含有エチレン性不飽和単量体に由来する構造単位が好ましい。 <Other structural units>
The present polymer may contain, in addition to the component (a), a structural unit derived from another ethylenically unsaturated monomer copolymerizable therewith (hereinafter, also referred to as “component (b)”). .. Examples of the component (b) include ethylenically unsaturated monomer compounds having anionic groups other than carboxy groups such as sulfonic acid groups and phosphoric acid groups, or nonionic ethylenically unsaturated monomers. The structural unit from which it is derived is included. These structural units are ethylenically unsaturated monomer compounds having anionic groups other than carboxy groups such as sulfonic acid groups and phosphoric acid groups, or monomers containing nonionic ethylenically unsaturated monomers. Can be introduced by copolymerizing. Among these, as the component (b), a structural unit derived from a nonionic ethylenically unsaturated monomer is preferable from the viewpoint of obtaining an electrode having good bending resistance, and the binding property of the binder and the slurry viscosity. (Meth) acrylamide and its derivatives are preferred because of their excellent properties. When a structural unit derived from a hydrophobic ethylenically unsaturated monomer having a solubility in water of 1 g / 100 ml or less is introduced as the component (b), strong interaction with the electrode material can be achieved, Good binding properties can be exhibited for the active material. This is preferable because it is possible to obtain a firm and good electrode mixture layer. A structural unit derived from an alicyclic structure-containing ethylenically unsaturated monomer is particularly preferable.
　非イオン性のエチレン性不飽和単量体としては、バインダーの結着性やスラリー粘度が優れる点で（メタ）アクリルアミド及びその誘導体等が好ましい。（メタ）アクリルアミド誘導体としては、例えば、イソプロピル（メタ）アクリルアミド、ｔ－ブチル（メタ）アクリルアミド、Ｎ－ｎ－ブトキシメチル（メタ）アクリルアミド、Ｎ－イソブトキシメチル（メタ）アクリルアミド等のＮ－アルキル（メタ）アクリルアミド化合物；ジメチル（メタ）アクリルアミド、ジエチル（メタ）アクリルアミド等のＮ，Ｎ－ジアルキル（メタ）アクリルアミド化合物が挙げられ、これらの内の１種を単独で使用してもよいし、２種以上を組み合わせて使用してもよい。 (Meth) acrylamide and its derivatives are preferable as the nonionic ethylenically unsaturated monomer because of their excellent binder binding properties and slurry viscosity. Examples of the (meth) acrylamide derivative include N-alkyl (s) such as isopropyl (meth) acrylamide, t-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide. (Meth) acrylamide compound; N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide, etc. may be mentioned, and one of these may be used alone, or two of them may be used. The above may be used in combination.
　（メタ）アクリルアミド及びその誘導体である（ｂ）成分の割合は、非架橋構造単位の総量に対し、例えば０質量％以上、９０質量％以下とすることができる。（ｂ）成分の割合は、また例えば１質量％以上、７０質量％以下、また例えば２質量％以上、６０質量％以下、また例えば５質量％以上、５０質量％以下、また例えば１０質量％以上、３０質量％以下である。また、非架橋構造単位の総量に対して（ｂ）成分を１質量％以上含む場合、電解液への親和性が向上するため、リチウムイオン電導性が向上する効果も期待できる。また、非架橋構造単位の総量に対して７０質量％以下含む場合、スラリー粘度の抑制に有用な場合がある。 The proportion of component (b), which is (meth) acrylamide and its derivative, can be, for example, 0% by mass or more and 90% by mass or less based on the total amount of the non-crosslinked structural units. The proportion of the component (b) is, for example, 1% by mass or more and 70% by mass or less, or 2% by mass or more and 60% by mass or less, or 5% by mass or more and 50% by mass or less, or 10% by mass or more, for example. , 30 mass% or less. When the component (b) is contained in an amount of 1% by mass or more with respect to the total amount of the non-crosslinked structural units, the affinity for the electrolytic solution is improved, and the effect of improving the lithium ion conductivity can also be expected. Further, when it is contained in an amount of 70% by mass or less based on the total amount of the non-crosslinked structural units, it may be useful for suppressing the slurry viscosity.
　その他に非イオン性のエチレン性不飽和単量体としては、例えば（メタ）アクリル酸エステルを用いてもよい。上記（メタ）アクリル酸エステルとしては、例えば、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ブチル、（メタ）アクリル酸イソブチル及び（メタ）アクリル酸２－エチルヘキシル等の（メタ）アクリル酸アルキルエステル化合物；（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸メチルシクロヘキシル等の（メタ）アクリル酸シクロアルキルエステル化合物；（メタ）アクリル酸２－メトキシエチル、（メタ）アクリル酸エトキシエチル等の（メタ）アクリル酸アルコキシアルキルエステル化合物；（メタ）アクリル酸ヒドロキシエチル、（メタ）アクリル酸ヒドロキシプロピル及び（メタ）アクリル酸ヒドロキシブチル等の（メタ）アクリル酸ヒドロキシアルキルエステル化合物等が挙げられ、これらの内の１種を単独で使用してもよいし、２種以上を組み合わせて使用してもよい。非イオン性のエチレン性不飽和単量体として（メタ）アクリル酸エステルを用いる場合、該（メタ）アクリル酸エステルに由来する構造単位の割合は、本重合体の非架橋構造単位の総量に対し、好ましくは１～３０質量％であり、より好ましくは５～３０質量％であり、さらに好ましくは１０～３０質量％である。また、この場合、上記（ａ）成分の割合は、本重合体の全構造単位に対し、好ましくは７０～９９質量％であり、より好ましくは７０～９５質量％であり、さらに好ましくは７０～９０質量％である。 In addition, as the nonionic ethylenically unsaturated monomer, for example, (meth) acrylic acid ester may be used. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. (Meth) acrylic acid alkyl ester compound; (meth) acrylic acid cycloalkyl ester such as (meth) acrylic acid cyclohexyl, (meth) acrylic acid methylcyclohexyl, etc .; (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid (Meth) acrylic acid alkoxyalkyl ester compounds such as ethoxyethyl; hydroxymethacrylic acid hydroxyalkyl ester compounds such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate Named You may be using one of these alone or may be used in combination of two or more. When a (meth) acrylic acid ester is used as the nonionic ethylenically unsaturated monomer, the ratio of the structural units derived from the (meth) acrylic acid ester is based on the total amount of the non-crosslinked structural units of the present polymer. , Preferably 1 to 30% by mass, more preferably 5 to 30% by mass, and further preferably 10 to 30% by mass. In this case, the ratio of the component (a) is preferably 70 to 99% by mass, more preferably 70 to 95% by mass, and further preferably 70 to 99% by mass based on the total structural units of the present polymer. It is 90% by mass.
　上記の中でも、リチウムイオン伝導性が高く、ハイレート特性がより向上する点から、（メタ）アクリル酸２－メトキシエチル及び（メタ）アクリル酸エトキシエチルなどの（メタ）アクリル酸アルコキシアルキル類等、エーテル結合を有する化合物が好ましく、（メタ）アクリル酸２－メトキシエチルがより好ましい。 Among the above, since the lithium ion conductivity is high and the high rate property is further improved, (meth) acrylic acid alkoxyalkyls such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, ethers, etc. A compound having a bond is preferable, and 2-methoxyethyl (meth) acrylate is more preferable.
　非イオン性のエチレン性不飽和単量体の中でも、重合速度が速いために一次鎖長の長い重合体が得られ、バインダーの結着力が良好となる点でアクリロイル基を有する化合物が好ましい。また、非イオン性のエチレン性不飽和単量体としては、得られる電極の耐屈曲性が良好となる点でホモポリマーのガラス転移温度（Ｔｇ）が０℃以下の化合物が好ましい。 Among the nonionic ethylenically unsaturated monomers, a compound having an acryloyl group is preferable in that a polymer having a long primary chain length can be obtained because of its high polymerization rate and the binding force of the binder is good. As the nonionic ethylenically unsaturated monomer, a compound having a homopolymer glass transition temperature (Tg) of 0 ° C. or lower is preferable in that the obtained electrode has good bending resistance.
＜架橋構造単位＞
　本重合体は、架橋構造単位として、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体に由来する架橋構造単位（以下、「（ｃ）成分」ともいう。）を備えることができる。 <Crosslinked structural unit>
The present polymer has, as a cross-linking structural unit, two or more (meth) acryloyl groups in one molecule, and a cross-linking structural unit derived from a cross-linkable monomer having a hydroxyl group (hereinafter, referred to as “(c) component”). Also referred to as).
　（ｃ）成分が有することができる、２個以上の（メタ）アクリロイル基は、２個以上のメタクリロイル基、１個以上のアクリロイル基及び１個以上のメタクリロイル基、２個以上のアクリロイル基などとすることができる。特に限定するものではないが、例えば２個以上６個以下の（メタ）アクリロイル基であり、また例えば２個以上５個以下の（メタ）アクリロイル基、また例えば２個以上４個以下の（メタ）アクリロイル基、また例えば２個以上３個以下の（メタ）アクリロイル基、また例えば２個の（メタ）アクリロイル基を備えことができる。 The two or more (meth) acryloyl groups that the component (c) may have include two or more methacryloyl groups, one or more acryloyl groups and one or more methacryloyl groups, two or more acryloyl groups. can do. It is not particularly limited, but is, for example, 2 or more and 6 or less (meth) acryloyl group, and is, for example, 2 or more and 5 or less (meth) acryloyl group, or, for example, 2 or more and 4 or less (meth ) An acryloyl group, for example, 2 or more and 3 or less (meth) acryloyl groups, for example, 2 (meth) acryloyl groups can be provided.
　（メタ）アクリロイル基は、本重合体の粒子表面の架橋密度を低くして水中での膨潤度を低減することができる。結着性向上の観点からは、（ｃ）成分が有する（メタ）アクリロイル基は、より好ましくはメタクリロイル基である。このため、（ｃ）成分が（メタ）アクリロイル基を２個有する２官能性化化合物である場合、当該（ｃ）成分は、例えば、結着性向上の観点からは、好ましい順に、ジメタクリロイル基、メタクリロイル基とアクリロイル基、ジアクリロイル基を備える。また、（ｃ）成分が有する（メタ）アクリロイル基は、合剤層組成物（スラリー）の粘度の観点からは、より好ましくは、アクリロイル基である。このため、上記２官能性化合物は、例えば、スラリー粘度抑制の観点からは、好ましい順に、ジアクリロイル基、メタクリロイル基とアクリロイル基、ジメタクリロイル基を備える。二次電池電極用バインダーとして意図する結着性及びスラリー粘度のほか、架橋構造単位量を考慮して、（ｃ）成分における（メタ）アクリロイル基の個数や組合せを適宜選択することができる。 The (meth) acryloyl group can reduce the crosslink density on the particle surface of the present polymer and reduce the degree of swelling in water. From the viewpoint of improving the binding property, the (meth) acryloyl group contained in the component (c) is more preferably a methacryloyl group. Therefore, when the component (c) is a difunctionalized compound having two (meth) acryloyl groups, the components (c) are, for example, from the viewpoint of improving the binding property, preferred dimethacryloyl groups. , A methacryloyl group, an acryloyl group, and a diacryloyl group. The (meth) acryloyl group contained in the component (c) is more preferably an acryloyl group from the viewpoint of the viscosity of the mixture layer composition (slurry). Therefore, the bifunctional compound includes, for example, a diacryloyl group, a methacryloyl group and an acryloyl group, and a dimethacryloyl group in a preferable order from the viewpoint of suppressing slurry viscosity. The number and combination of (meth) acryloyl groups in the component (c) can be appropriately selected in consideration of the binding property and slurry viscosity intended as a binder for secondary battery electrodes, as well as the amount of the crosslinking structural unit.
　（ｃ）成分が有することができる水酸基は、１個以上であればよく、特に限定するものではないが、例えば１個以上３個以下であり、また例えば１個以上２個以下であり、また例えば１個である。水酸基が多いほど、重合体粒子内の相互作用が大きくなる傾向があると考えられる。二次電池電極用バインダーとして意図するスラリー粘度等のほか、架橋構造単位量を考慮して、（ｃ）成分における水酸基の個数を適宜選択することができる。 The number of hydroxyl groups that the component (c) can have is not particularly limited as long as it is 1 or more, and is, for example, 1 or more and 3 or less, or, for example, 1 or more and 2 or less, and For example, one. It is considered that as the number of hydroxyl groups increases, the interaction within the polymer particles tends to increase. The number of hydroxyl groups in the component (c) can be appropriately selected in consideration of the viscosity of the slurry intended as the binder for the secondary battery electrode and the like, as well as the amount of the cross-linking structural unit.
　（ｃ）成分としては、特に限定するものではないが、例えば、トリメチロールプロパンジ（メタ）アクリレート、ペンタエリスリトールのジ又はトリ（メタ）アクリレート、ジペンタエリスリトールのジ、トリ、テトラ又はペンタ（メタ）アクリレート、グリセリンジ（メタ）アクリレート、２－ヒドロキシ－３－アクリロイロキシプロピルメタクリレート等を用いることができる。（ｃ）成分は、１種のみを用いてもよいが、２種以上を組みあわせて用いることができる。 The component (c) is not particularly limited, and examples thereof include trimethylolpropane di (meth) acrylate, pentaerythritol di- or tri (meth) acrylate, dipentaerythritol di-, tri-, tetra- or penta- (meta). ) Acrylate, glycerin di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate and the like can be used. As the component (c), only one type may be used, but two or more types may be used in combination.
　（ｃ）成分は、特に限定するものではないが、例えば、非架橋構造単位の全量を１００質量部としたとき、０．０１質量部以上、２０質量部以下である。０．０１質量部未満であると、結着性が得られずスラリー粘度が高くなりすぎ、２０質量部を超えると、結着性がかえって得られなくなる。（ｃ）成分は、また例えば０．０２質量部以上であり、また例えば０．０４質量部以上であり、また例えば０．０５質量部以上であり、また例えば０．１質量部以上であり、また例えば０．２質量部以上である。（ｃ）成分は、また例えば１５質量部以下であり、また例えば１２質量部以下であり、また例えば１０質量部以下であり、また例えば９質量部以下であり、また例えば７質量部以下であり、また例えば５質量部以下であり、また例えば３質量部以下であり、また例えば２質量部以下であり、又は１質量部以下である。（ｃ）成分の好ましい含有量の範囲は、これらの上限及び下限を適宜組み合わせることができるが、例えば、０．１質量部以上１５質量部以下であり、また例えば０．１質量部以上１０質量部以下であり、また例えば０．２質量部以上９質量部以下であり、また例えば０．２質量部以上７質量部以下であり、また例えば０．２質量部以上５質量部以下であり、また例えば０．２質量部以上２質量部以下であり、また例えば０．２質量部以上１質量部以下である。 The component (c) is not particularly limited, but is, for example, 0.01 part by mass or more and 20 parts by mass or less when the total amount of the non-crosslinked structural units is 100 parts by mass. If it is less than 0.01 parts by mass, the binding property will not be obtained and the viscosity of the slurry will be too high. If it exceeds 20 parts by mass, the binding property will not be obtained. The component (c) is, for example, 0.02 parts by mass or more, and for example, 0.04 parts by mass or more, for example, 0.05 parts by mass or more, and for example, 0.1 parts by mass or more, Further, for example, it is 0.2 parts by mass or more. The component (c) is, for example, 15 parts by mass or less, for example, 12 parts by mass or less, for example, 10 parts by mass or less, for example, 9 parts by mass or less, and for example, 7 parts by mass or less. Also, for example, 5 parts by mass or less, and for example, 3 parts by mass or less, and for example, 2 parts by mass or less, or 1 part by mass or less. The preferable range of the content of the component (c) may be a combination of the upper limit and the lower limit thereof, but is, for example, 0.1 part by mass or more and 15 parts by mass or less, and for example, 0.1 part by mass or more and 10 parts by mass. Parts or less, for example 0.2 parts by mass or more and 9 parts by mass or less, and for example 0.2 parts by mass or more and 7 parts by mass or less, and for example 0.2 parts by mass or more and 5 parts by mass or less, Further, it is, for example, 0.2 parts by mass or more and 2 parts by mass or less, and for example, 0.2 parts by mass or more and 1 part by mass or less.
　本重合体は、（ｃ）成分以外の架橋構造単位を備えることもできる。かかる架橋構造単位は、２個以上の重合性不飽和基を有する多官能重合性単量体及び加水分解性シリル基等の自己架橋可能な架橋性官能基を有する単量体等に由来する構造単位が挙げられる。多官能重合性単量体は、（メタ）アクリロイル基、アルケニル基等の重合性官能基を分子内に２つ以上有する化合物であり、多官能（メタ）アクリレート化合物、多官能アルケニル化合物、（メタ）アクリロイル基及びアルケニル基の両方を有する化合物等が挙げられる。これらの化合物は、１種のみを単独で用いてもよいし、２種以上を組み合わせて用いてもよい。 The present polymer may have a cross-linking structural unit other than the component (c). The cross-linking structural unit is derived from a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups and a monomer having a self-crosslinkable crosslinkable functional group such as a hydrolyzable silyl group. The unit is mentioned. The polyfunctional polymerizable monomer is a compound having two or more polymerizable functional groups such as a (meth) acryloyl group and an alkenyl group in the molecule, and is a polyfunctional (meth) acrylate compound, a polyfunctional alkenyl compound, (meth ) Examples thereof include compounds having both an acryloyl group and an alkenyl group. These compounds may be used alone or in combination of two or more.
　多官能（メタ）アクリレート化合物としては、エチレングリコールジ（メタ）アクリレート、プロピレングリコールジ（メタ）アクリレート、１，６－ヘキサンジオールジ（メタ）アクリレート、ポリエチレングリコールジ（メタ）アクリレート、ポリプロピレングリコールジ（メタ）アクリレート等の２価アルコールのジ（メタ）アクリレート類；トリメチロールプロパントリ（メタ）アクリレート、トリメチロールプロパンエチレンオキサイド変性体のトリ（メタ）アクリレート、グリセリントリ（メタ）アクリレート、ペンタエリスリトールテトラ（メタ）アクリレート等の３価以上の多価アルコールのトリ（メタ）アクリレート、テトラ（メタ）アクリレート等のポリ（メタ）アクリレート；メチレンビスアクリルアミド、ヒドロキシエチレンビスアクリルアミド等のビスアミド類等を挙げることができる。 Examples of the polyfunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di ( Di (meth) acrylates of dihydric alcohols such as (meth) acrylate; trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tetra ( Poly (meth) acrylates such as tri (meth) acrylates of trihydric or higher polyhydric alcohols such as (meth) acrylates, tetra (meth) acrylates; methylenebisacrylamide, hydro Shi ethylene bisacrylamide bisamides such as and the like.
　多官能アルケニル化合物としては、トリメチロールプロパンジアリルエーテル、トリメチロールプロパントリアリルエーテル、ペンタエリスリトールジアリルエーテル、ペンタエリスリトールトリアリルエーテル、テトラアリルオキシエタン、ポリアリルサッカロース等の多官能アリルエーテル化合物；ジアリルフタレート等の多官能アリル化合物；ジビニルベンゼン等の多官能ビニル化合物等を挙げることができる。 Examples of the polyfunctional alkenyl compound include trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, polyallyl saccharose and the like; diallyl phthalate and the like. Examples of the polyfunctional allyl compound: a polyfunctional vinyl compound such as divinylbenzene.
　（メタ）アクリロイル基及びアルケニル基の両方を有する化合物としては、（メタ）アクリル酸アリル、（メタ）アクリル酸イソプロペニル、（メタ）アクリル酸ブテニル、（メタ）アクリル酸ペンテニル、（メタ）アクリル酸２－（２－ビニロキシエトキシ）エチル等を挙げることができる。 Examples of the compound having both a (meth) acryloyl group and an alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, and (meth) acrylic acid. 2- (2-vinyloxyethoxy) ethyl and the like can be mentioned.
　上記自己架橋可能な架橋性官能基を有する単量体の具体的な例としては、加水分解性シリル基含有ビニル単量体、Ｎ－メチロール（メタ）アクリルアミド、Ｎ－メトキシアルキル（メタ）アクリレート等が挙げられる。これらの化合物は、１種単独であるいは２種以上を組み合わせて用いることができる。 Specific examples of the monomer having a crosslinkable functional group capable of self-crosslinking include hydrolyzable silyl group-containing vinyl monomer, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate and the like. Is mentioned. These compounds may be used alone or in combination of two or more.
　加水分解性シリル基含有ビニル単量体としては、加水分解性シリル基を少なくとも１個有するビニル単量体であれば、特に限定されない。例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルメチルジメトキシシラン、ビニルジメチルメトキシシランン等のビニルシラン類；アクリル酸トリメトキシシリルプロピル、アクリル酸トリエトキシシリルプロピル、アクリル酸メチルジメトキシシリルプロピル等のシリル基含有アクリル酸エステル類；メタクリル酸トリメトキシシリルプロピル、メタクリル酸トリエトキシシリルプロピル、メタクリル酸メチルジメトキシシリルプロピル、メタクリル酸ジメチルメトキシシリルプロピル等のシリル基含有メタクリル酸エステル類；トリメトキシシリルプロピルビニルエーテル等のシリル基含有ビニルエーテル類；トリメトキシシリルウンデカン酸ビニル等のシリル基含有ビニルエステル類等を挙げることができる。 The hydrolyzable silyl group-containing vinyl monomer is not particularly limited as long as it is a vinyl monomer having at least one hydrolyzable silyl group. For example, vinyl silanes such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl methyl dimethoxy silane, vinyl dimethyl methoxy silane; silyl triacrylate such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylate, etc. Group-containing acrylic acid esters; trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate, etc. silyl group-containing methacrylates; trimethoxysilylpropyl vinyl ether, etc. Examples of the silyl group-containing vinyl ethers include silyl group-containing vinyl esters such as trimethoxysilyl vinyl undecanoate.
　（ｃ）成分以外の架橋構造単位は、特に限定するものではないが、例えば、非架橋性単量体の総量１００質量部に対して、０．１質量部以上、５．０質量部以下、備えることができる。同構造単位は、０．２質量部、３．０質量部以下であってもよく、０．３質量部、２．０質量部以下であってもよく、０．５質量部、１．０質量部以下であってもよい。 The cross-linking structural unit other than the component (c) is not particularly limited, but is, for example, 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the total amount of the non-crosslinking monomers. Can be prepared. The structural unit may be 0.2 parts by mass, 3.0 parts by mass or less, 0.3 parts by mass, 2.0 parts by mass or less, 0.5 parts by mass, 1.0 part by mass. It may be less than or equal to parts by mass.
＜中和度＞
　本重合体は、本組成物中において、中和度が２０～１００モル％となるように、エチレン性不飽和カルボン酸単量体由来のカルボキシ基等の酸基が中和され、塩の態様として用いることが好ましい。上記中和度は５０～１００モル％であることがより好ましく、例えば６０モル％以上、また例えば６５モル％以上、また例えば７０モル％以上、また例えば７５モル％以上、また例えば８０モル％以上、また例えば８５モル％以上、また例えば９０モル％以上、また例えば９５モル％以上である。中和度が５０モル％以上の場合、水膨潤性が良好となり分散安定化効果が得やすいという点で好ましい。 <Neutralization degree>
In the present polymer, acid groups such as a carboxy group derived from an ethylenically unsaturated carboxylic acid monomer are neutralized so that the degree of neutralization in the composition is 20 to 100 mol%, and a salt form is obtained. It is preferable to use as. The above-mentioned degree of neutralization is more preferably 50 to 100 mol%, for example 60 mol% or more, also for example 65 mol% or more, for example 70 mol% or more, for example 75 mol% or more, for example 80 mol% or more. And, for example, 85 mol% or more, also 90 mol% or more, and for example 95 mol% or more. When the degree of neutralization is 50 mol% or more, the water swelling property is good and the dispersion stabilizing effect is easily obtained, which is preferable.
　本明細書では、上記中和度は、カルボキシ基等の酸基を有する単量体及び中和に用いる中和剤の仕込み値から計算により算出することができる。なお、中和度は本重合体を、減圧条件下、８０℃で３時間乾燥処理後の粉末をＩＲ測定し、カルボン酸のＣ＝Ｏ基由来のピークとカルボン酸塩のＣ＝Ｏ基由来のピークの強度比より確認することができる。 In the present specification, the degree of neutralization can be calculated from the charged values of the monomer having an acid group such as a carboxy group and the neutralizing agent used for neutralization. The degree of neutralization was determined by IR measurement of the powder obtained by drying the present polymer at 80 ° C. for 3 hours under reduced pressure, and the peak derived from the C═O group of the carboxylic acid and the C═O group of the carboxylate. It can be confirmed from the intensity ratio of the peak.
＜架橋重合体又はその塩の製造方法／二次電池電極用バインダーの製造方法＞
　本バインダーのバインダー成分である本重合体は、以下の準備工程（重合工程）により製造することができる。以下に説明する本重合体の製造方法は、本バインダーの製造方法としても実施できる。 <Method for producing crosslinked polymer or salt thereof / Method for producing binder for secondary battery electrode>
The present polymer, which is a binder component of the present binder, can be produced by the following preparation step (polymerization step). The method for producing the present polymer described below can also be carried out as a method for producing the present binder.
＜準備工程＞
　準備工程は、本重合体を準備する工程である。本重合体を入手するか又は本重合体を重合により取得する工程（重合工程）である。重合工程は、少なくとも、既述の（ａ）成分が由来する非架橋性単量体と、（ｃ）成分が由来する架橋性単量体と、を含有する単量体組成物を重合する工程である。 <Preparation process>
The preparation step is a step of preparing the present polymer. This is a step of obtaining the present polymer or obtaining the present polymer by polymerization (polymerization step). The polymerization step is a step of polymerizing a monomer composition containing at least the non-crosslinkable monomer from which the component (a) is derived and the crosslinkable monomer from which the component (c) is derived. Is.
＜重合工程＞
＜重合方法＞
　本重合体は、溶液重合、沈殿重合、懸濁重合、乳化重合等の公知の重合方法を使用することが可能であるが、生産性の点で沈殿重合及び懸濁重合（逆相懸濁重合）が好ましい。結着性等に関してより良好な性能が得られる点で、沈殿重合、懸濁重合、乳化重合等の不均一系の重合法が好ましく、中でも均一性に優れた小粒子径の重合体微粒子を得易い点で沈殿重合法がより好ましい。沈殿重合は、原料である不飽和単量体を溶解するが、生成する重合体を実質溶解しない溶媒中で重合反応を行うことにより重合体を製造する方法である。重合の進行とともにポリマー粒子は凝集及び成長により大きくなり、数十ｎｍ～数百ｎｍの一次粒子が数μｍ～数十μｍに二次凝集したポリマー粒子の分散液が得られる。ポリマーの粒子サイズを制御するために分散安定剤を使用することもできる。尚、分散安定剤や重合溶剤等を選定することにより上記二次凝集を抑制することもできる。一般に、二次凝集を抑制した沈殿重合は、分散重合とも呼ばれる。 <Polymerization process>
<Polymerization method>
For the present polymer, known polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, and emulsion polymerization can be used, but from the viewpoint of productivity, precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) ) Is preferred. In terms of obtaining better performance with respect to binding properties, etc., a heterogeneous polymerization method such as precipitation polymerization, suspension polymerization, or emulsion polymerization is preferable, and among them, polymer fine particles having a small particle size excellent in uniformity are obtained. The precipitation polymerization method is more preferable because it is easy. Precipitation polymerization is a method of producing a polymer by carrying out a polymerization reaction in a solvent that dissolves an unsaturated monomer that is a raw material but does not substantially dissolve a produced polymer. As the polymerization progresses, the polymer particles become larger due to aggregation and growth, and a dispersion liquid of polymer particles in which primary particles of several tens nm to several hundreds nm are secondarily aggregated to several μm to several tens μm is obtained. Dispersion stabilizers can also be used to control the particle size of the polymer. The secondary aggregation can be suppressed by selecting a dispersion stabilizer or a polymerization solvent. Generally, precipitation polymerization in which secondary aggregation is suppressed is also called dispersion polymerization.
＜重合溶媒＞
　沈殿重合の場合、重合溶媒は、使用する単量体の種類等を考慮して水及び各種有機溶剤等から選択される溶媒を使用することができる。より一次鎖長の長い重合体を得るためには、連鎖移動定数の小さい溶媒を使用することが好ましい。 <Polymerization solvent>
In the case of precipitation polymerization, a solvent selected from water, various organic solvents, and the like can be used as the polymerization solvent in consideration of the type of monomer to be used. In order to obtain a polymer having a longer primary chain length, it is preferable to use a solvent having a small chain transfer constant.
　具体的な重合溶媒としては、メタノール、ｔ－ブチルアルコール、アセトン、メチルエチルケトン、アセトニトリル及びテトラヒドロフラン等の水溶性溶剤の他、ベンゼン、酢酸エチル、ジクロロエタン、ｎ－ヘキサン、シクロヘキサン及びｎ－ヘプタン等が挙げられ、これらの１種を単独であるいは２種以上を組み合わせて用いることができる。又は、これらと水との混合溶媒として用いてもよい。本明細書において水溶性溶剤とは、２０℃における水への溶解度が１０ｇ／１００ｍｌより大きいものを指す。上記の内、粗大粒子の生成や反応器への付着が小さく重合安定性が良好であること、析出した重合体微粒子が二次凝集しにくい（若しくは二次凝集が生じても水媒体中で解れやすい）こと、連鎖移動定数が小さく重合度（一次鎖長）の大きい重合体が得られること、及び後述する工程中和の際に操作が容易であること等の点で、メチルエチルケトン及びアセトニトリルが好ましい。 Specific polymerization solvents include water-soluble solvents such as methanol, t-butyl alcohol, acetone, methyl ethyl ketone, acetonitrile and tetrahydrofuran, as well as benzene, ethyl acetate, dichloroethane, n-hexane, cyclohexane and n-heptane. These can be used alone or in combination of two or more. Alternatively, they may be used as a mixed solvent of these and water. In the present specification, the water-soluble solvent refers to a solvent having a solubility in water at 20 ° C of more than 10 g / 100 ml. Among the above, the formation of coarse particles and the small adhesion to the reactor are good and the polymerization stability is good, and the precipitated polymer particles are difficult to secondary aggregate (or even if secondary aggregation occurs, it is unraveled in an aqueous medium). Methyl ethyl ketone and acetonitrile are preferable in that they are easy), a polymer having a small chain transfer constant and a large degree of polymerization (primary chain length) can be obtained, and that the operation is easy at the time of the step neutralization described later. ..
　また、同じく工程中和において中和反応を安定かつ速やかに進行させるため、重合溶媒中に高極性溶媒を少量加えておくことが好ましい。係る高極性溶媒としては、好ましくは水及びメタノールが挙げられる。高極性溶媒の使用量は、媒体の全質量に基づいて好ましくは０．０５～１０．０質量％であり、より好ましくは０．１～５．０質量％、さらに好ましくは０．１～１．０質量％である。高極性溶媒の割合が０．０５質量％以上であれば、上記中和反応への効果が認められ、１０．０質量％以下であれば重合反応への悪影響も見られない。また、アクリル酸等の親水性の高いエチレン性不飽和カルボン酸単量体の重合では、高極性溶媒を加えた場合には重合速度が向上し、一次鎖長の長い重合体を得やすくなる。高極性溶媒の中でも特に水は上記重合速度を向上させる効果が大きく好ましい。 Similarly, in the process neutralization, it is preferable to add a small amount of a highly polar solvent to the polymerization solvent so that the neutralization reaction proceeds stably and quickly. As such a highly polar solvent, water and methanol are preferably mentioned. The amount of the highly polar solvent used is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and further preferably 0.1 to 1 based on the total mass of the medium. It is 0.0 mass%. When the proportion of the highly polar solvent is 0.05% by mass or more, the effect on the neutralization reaction is recognized, and when it is 10.0% by mass or less, no adverse effect on the polymerization reaction is observed. In addition, in the polymerization of highly hydrophilic ethylenically unsaturated carboxylic acid monomer such as acrylic acid, when a highly polar solvent is added, the polymerization rate is improved, and a polymer having a long primary chain length is easily obtained. Among the highly polar solvents, water is particularly preferable because it has a large effect of improving the polymerization rate.
＜単量体及びその使用量＞
　本製造方法においては、例えば、非架橋性単量体の総量に対して、（ａ）成分の由来となるエチレン性不飽和カルボン酸単量体を１０質量％以上、１００質量％以下、及び（ｂ）成分の由来となる他のエチレン性不飽和単量体を０質量％以上、９０質量％以下を含む単量体を、（ｃ）成分の由来となる架橋性単量体を非架橋性単量体１００質量部に対して、０．０１質量部以上２０質量部以下含有する単量体組成物を重合する重合工程を備えることが好ましい。上記重合工程により、本重合体には、非架橋構造単位に対して、（ａ）成分が１０質量％以上、１００質量％以下導入され、（ｂ）成分が０質量％以上、９０質量％以下導入される。（ａ）成分が由来するエチレン性不飽和カルボン酸単量体及び（ｂ）成分が由来する他のエチレン性不飽和単量体の使用量は、既に説明した、非架橋構造単位に対する含有量に対応するように適宜設定される。また、（ｃ）成分が由来する架橋性単量体の使用量についても、既に説明した（ｃ）成分の含有量に対応するように適宜設定される。 <Monomer and amount used>
In the present production method, for example, with respect to the total amount of non-crosslinkable monomers, the amount of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived is 10% by mass or more and 100% by mass or less, and ( b) A monomer containing 0% by mass or more and 90% by mass or less of another ethylenically unsaturated monomer from which the component is derived, and a non-crosslinkable monomer from the crosslinkable monomer from which the component (c) is derived. It is preferable to include a polymerization step of polymerizing a monomer composition containing 0.01 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the monomer. By the polymerization step, the component (a) is introduced into the present polymer in an amount of 10% by mass or more and 100% by mass or less, and the component (b) is 0% by mass or more and 90% by mass or less with respect to the non-crosslinked structural unit. be introduced. The amount of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived and the amount of the other ethylenically unsaturated monomer from which the component (b) is derived are the same as those described above with respect to the content of the non-crosslinked structural unit. It is appropriately set to correspond. Further, the amount of the crosslinkable monomer from which the component (c) is derived is also appropriately set so as to correspond to the content of the component (c) already described.
　なお、エチレン性不飽和カルボン酸単量体は、未中和の状態であってもよいし、また、その少なくとも一部が中和された塩の状態であってもよい。重合速度及び結着性の観点から、エチレン性不飽和カルボン酸単量体の中和度は、例えば１０モル％以下であり、また例えば５モル％以下であり、未中和であることが好ましい。 The ethylenically unsaturated carboxylic acid monomer may be in a non-neutralized state, or may be in a salt state in which at least a part thereof is neutralized. From the viewpoint of the polymerization rate and the binding property, the degree of neutralization of the ethylenically unsaturated carboxylic acid monomer is, for example, 10 mol% or less, and for example, 5 mol% or less, and it is preferably unneutralized. ..
　なお、本明細書によれば、こうした単量体組成物は、二次電池電極用バインダーを製造するために好適な組成物である。 According to the present specification, such a monomer composition is a composition suitable for producing a binder for secondary battery electrodes.
　重合工程における単量体の総濃度は、例えば２．０質量％以上、また例えば４．０質量％以上、また例えば１０．０質量％以上程度であってもよいが、結着性の観点から好ましくは、例えば１０．０質量％以上であり、また例えば１３．０質量％以上である。後述するように、塩基化合物の存在下に重合工程を行う場合には、高い単量体濃度であっても重合反応を安定して実施できる。単量体濃度はより好ましくは１５．０質量％以上であり、更に好ましくは１７．０質量％以上であり、一層好ましくは１９．０質量％以上である。単量体濃度はなお好ましくは２０．０質量％以上であり、より一層好ましくは２２．０質量％以上であり、更に一層好ましくは２５．０質量％以上である。一般に、重合時の単量体濃度を高くするほど高分子量化が可能であり、一次鎖長の長い重合体を製造することができる。本重合体は、十分に長い一次鎖長を有する重合体に適度な架橋を施した微架橋重合体であるため、その一次鎖長を直接測定することは、分析的に困難である。一般的には、重合体の一次鎖長は溶液粘度と相関することが知られているが、本重合体の場合にはその架橋度によっても溶液粘度は変動する。よって、上記の方法で得られた本重合体を、本重合体の構造又は特性で規定することは非常に困難である。なお、本明細書において「単量体濃度」とは、重合を開始する時点における反応液中の単量体濃度を示す。 The total concentration of monomers in the polymerization step may be, for example, 2.0% by mass or more, for example 4.0% by mass or more, and for example 10.0% by mass or more, but from the viewpoint of binding property. Preferably, it is, for example, 10.0 mass% or more, and for example, 13.0 mass% or more. As will be described later, when the polymerization step is performed in the presence of a basic compound, the polymerization reaction can be stably performed even at a high monomer concentration. The monomer concentration is more preferably 15.0% by mass or more, further preferably 17.0% by mass or more, and further preferably 19.0% by mass or more. The monomer concentration is more preferably 20.0% by mass or more, even more preferably 22.0% by mass or more, and even more preferably 25.0% by mass or more. Generally, the higher the monomer concentration at the time of polymerization, the higher the molecular weight can be made, and the polymer having a long primary chain length can be produced. Since the present polymer is a finely crosslinked polymer obtained by appropriately crosslinking a polymer having a sufficiently long primary chain length, it is analytically difficult to directly measure the primary chain length. It is generally known that the primary chain length of a polymer correlates with the solution viscosity, but in the case of the present polymer, the solution viscosity also varies depending on the degree of crosslinking. Therefore, it is very difficult to define the present polymer obtained by the above method by the structure or characteristics of the present polymer. In the present specification, the “monomer concentration” refers to the monomer concentration in the reaction liquid at the time of starting the polymerization.
　単量体濃度の上限値は、使用する単量体及び溶媒の種類、並びに、重合方法及び各種重合条件等により異なるが、重合反応熱の除熱が可能であれば、沈殿重合では概ね４０質量％程度、懸濁重合では概ね５０質量％程度、乳化重合では概ね７０質量％程度である。 The upper limit of the monomer concentration varies depending on the type of the monomer and the solvent used, the polymerization method, various polymerization conditions, etc., but if the heat of the polymerization reaction can be removed, it is about 40 mass in the precipitation polymerization. %, About 50% by mass in suspension polymerization, and about 70% by mass in emulsion polymerization.
＜塩基化合物の使用＞
　本製造方法では、塩基化合物の存在下、重合工程を実施してもよい。このようにして得られた本重合体を含むバインダーは高い結着性を発揮することができる。また、塩基化合物の存在下において、エチレン性不飽和カルボン酸単量体を含む単量体組成物を重合した場合には、重合安定性が向上し、高い単量体濃度であっても本重合体を安定に製造することができる。 <Use of basic compound>
In the present production method, the polymerization step may be carried out in the presence of a basic compound. The binder containing the present polymer thus obtained can exhibit high binding properties. Further, when a monomer composition containing an ethylenically unsaturated carboxylic acid monomer is polymerized in the presence of a basic compound, the polymerization stability is improved, and even when the monomer concentration is high, the main composition The coalesced product can be manufactured stably.
　塩基化合物存在下において重合反応を行うことにより、例えば１３．０質量％を超えるような高い単量体濃度条件下であっても、重合反応を安定に実施することができる。このような高い単量体濃度で重合して得られた重合体は、分子量が高いため（一次鎖長が長いため）結着性にも優れる。 By performing the polymerization reaction in the presence of a base compound, the polymerization reaction can be stably performed even under a high monomer concentration condition of, for example, more than 13.0 mass%. A polymer obtained by polymerizing at such a high monomer concentration has a high molecular weight (because of its long primary chain length) and is therefore excellent in binding property.
　塩基化合物は、いわゆるアルカリ性化合物であり、無機塩基化合物及び有機塩基化合物のいずれを用いてもよい。無機塩基化合物としては、水酸化リチウム、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物、水酸化カルシウム、水酸化マグネシウム等のアルカリ土類金属水酸化物、炭酸ナトリウム、炭酸カリウム等のアルカリ金属炭酸塩、炭酸水素ナトリウム、炭酸水素カリウム等のアルカリ金属炭酸水素塩が挙げられる。これらの１種又は２種以上を用いることができる。有機塩基化合物としては、アンモニアの他、例えば、モノメチルアミン、ジメチルアミン、トリメチルアミン、モノエチルアミン、ジエチルアミン、トリエチルアミン、モノブチルアミン、ジブチルアミン、トリブチルアミン、モノヘキシルアミン、ジヘキシルアミン、トリヘキシルアミン、トリオクチルアミン及びトリドデシルアミン等のＮ－アルキル置換アミン；モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、プロパノールアミン、ジメチルエタノールアミン及びＮ，Ｎ－ジメチルエタノールアミン等の（アルキル）アルカノールアミン；ピリジン、ピペリジン、ピペラジン、１，８－ビス（ジメチルアミノ）ナフタレン、モルホリン及びジアザビシクロウンデセン（ＤＢＵ）等の環状アミン；ジエチレントリアミン、Ｎ、Ｎ－ジメチルベンジルアミンなどの有機アミン化合物が挙げられ、これらの内の１種又は２種以上を用いることができる。これらの内でも、結着性の観点からアンモニアを除く有機アミン化合物が好ましい。 The basic compound is a so-called alkaline compound, and either an inorganic basic compound or an organic basic compound may be used. Examples of the inorganic base compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, alkali metals such as sodium carbonate and potassium carbonate. Examples thereof include alkali metal hydrogencarbonates such as metal carbonates, sodium hydrogencarbonate and potassium hydrogencarbonate. These 1 type (s) or 2 or more types can be used. As the organic base compound, in addition to ammonia, for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monobutylamine, dibutylamine, tributylamine, monohexylamine, dihexylamine, trihexylamine, trioctylamine. And N-alkyl-substituted amines such as tridodecylamine; (ethyl) alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine and N, N-dimethylethanolamine; pyridine, piperidine, piperazine, Cyclic amines such as 1,8-bis (dimethylamino) naphthalene, morpholine and diazabicycloundecene (DBU); diethylene tria Emissions, N, N-organic amine compounds such as dimethylbenzylamine, and the like, may be used alone or two or more of these. Among these, organic amine compounds excluding ammonia are preferable from the viewpoint of binding property.
　重合工程において塩基化合物を用いる場合には、上記エチレン性不飽和カルボン酸単量体に対し、０．００１モル％以上の塩基化合物を用いることが好ましい。０．００１モル％以上の塩基化合物存在下で重合反応を行うことにより、重合安定性を向上することができ、高い単量体濃度条件でも円滑に重合反応が進行する。エチレン性不飽和カルボン酸単量体に対する塩基化合物の使用量は、好ましくは０．０１モル％以上であり、より好ましくは０．０３モル％以上であり、さらに好ましくは０．０５モル％以上である。塩基化合物の使用量は、０．３モル％以上であってもよく、０．５モル％以上であってもよい。また、塩基化合物の使用量の上限は、４．０モル％以下であることが好ましい。４．０モル％以下の塩基化合物存在下で重合反応を行うことにより、重合安定性を向上することができ、高い単量体濃度条件でも円滑に重合反応が進行する。エチレン性不飽和カルボン酸単量体に対する塩基化合物の使用量は、好ましくは３．０モル％以下であり、より好ましくは２．０モル％以下であり、さらに好ましくは１．０モル％以下である。尚、本明細書では、塩基化合物の使用量は、エチレン性不飽和カルボン酸単量体に対して用いた塩基化合物のモル濃度を表したものであり、中和度を意味するものではない。すなわち、用いる塩基化合物の価数は考慮しない。 When a base compound is used in the polymerization step, it is preferable to use 0.001 mol% or more of the base compound with respect to the ethylenically unsaturated carboxylic acid monomer. By carrying out the polymerization reaction in the presence of 0.001 mol% or more of the base compound, the polymerization stability can be improved, and the polymerization reaction proceeds smoothly even under a high monomer concentration condition. The amount of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, still more preferably 0.05 mol% or more. is there. The amount of the base compound used may be 0.3 mol% or more, or may be 0.5 mol% or more. Further, the upper limit of the amount of the basic compound used is preferably 4.0 mol% or less. By carrying out the polymerization reaction in the presence of a base compound in an amount of 4.0 mol% or less, the polymerization stability can be improved, and the polymerization reaction proceeds smoothly even under a high monomer concentration condition. The amount of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer is preferably 3.0 mol% or less, more preferably 2.0 mol% or less, further preferably 1.0 mol% or less. is there. In this specification, the amount of the base compound used represents the molar concentration of the base compound used with respect to the ethylenically unsaturated carboxylic acid monomer, and does not mean the degree of neutralization. That is, the valence of the basic compound used is not considered.
＜重合開始剤＞
　重合開始剤は、アゾ系化合物、有機過酸化物、無機過酸化物等の公知の重合開始剤を用いることができるが、特に限定されるものではない。熱開始、還元剤を併用したレドックス開始、ＵＶ開始等、公知の方法で適切なラジカル発生量となるように使用条件を調整することができる。一次鎖長の長い架橋重合体を得るためには、製造時間が許容される範囲内で、ラジカル発生量がより少なくなるように条件を設定することが好ましい。 <Polymerization initiator>
As the polymerization initiator, known polymerization initiators such as azo compounds, organic peroxides and inorganic peroxides can be used, but are not particularly limited. The use conditions can be adjusted by a known method such as thermal initiation, redox initiation using a reducing agent in combination, UV initiation, etc., so that an appropriate amount of radicals is generated. In order to obtain a crosslinked polymer having a long primary chain length, it is preferable to set the conditions so that the radical generation amount is smaller within a range where the production time is allowed.
　上記アゾ系化合物としては、２，２’－アゾビス（２，４－ジメチルバレロニトリル）、２，２’－アゾビス（Ｎ－ブチル－２－メチルプロピオンアミド）、２－（ｔｅｒｔ－ブチルアゾ）－２－シアノプロパン、２，２’－アゾビス（２，４，４－トリメチルペンタン）、２，２’－アゾビス（２－メチルプロパン）等が挙げられ、これらの内の１種又は２種以上を用いることができる。 Examples of the azo compounds include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (N-butyl-2-methylpropionamide), 2- (tert-butylazo) -2. -Cyanopropane, 2,2'-azobis (2,4,4-trimethylpentane), 2,2'-azobis (2-methylpropane), etc., and one or more of them are used. be able to.
　上記有機過酸化物としては、２，２－ビス（４，４－ジ－ｔ－ブチルパーオキシシクロヘキシル）プロパン（日油社製、商品名「パーテトラＡ」）、１，１－ジ（ｔ－ヘキシルパーオキシ）シクロヘキサン（同「パーヘキサＨＣ」）、１，１－ジ（ｔ－ブチルパーオキシ）シクロヘキサン（同「パーヘキサＣ」）、ｎ－ブチル－４，４－ジ（ｔ－ブチルパーオキシ）バレレート（同「パーヘキサＶ」）、２，２－ジ（ｔ－ブチルパーオキシ）ブタン（同「パーヘキサ２２」）、ｔ－ブチルハイドロパーオキサイド（同「パーブチルＨ」）、クメンハイドロパーオキサイド（日油社製、商品名「パークミルＨ」）、１，１，３，３－テトラメチルブチルハイドロパーオキサイド（同「パーオクタＨ」）、ｔ－ブチルクミルパーオキサイド（同「パーブチルＣ」）、ジ－ｔ－ブチルパーオキサイド（同「パーブチルＤ」）、ジ－ｔ－ヘキシルパーオキサイド（同「パーヘキシルＤ」）、ジ（３，５，５－トリメチルヘキサノイル）パーオキサイド（同「パーロイル３５５」）、ジラウロイルパーオキサイド（同「パーロイルＬ」）、ビス（４－ｔ－ブチルシクロヘキシル）パーオキシジカーボネート（同「パーロイルＴＣＰ」）、ジ－２－エチルヘキシルパーオキシジカーボネート（同「パーロイルＯＰＰ」）、ジ－ｓｅｃ－ブチルパーオキシジカーボネート（同「パーロイルＳＢＰ」）、クミルパーオキシネオデカノエート（同「パークミルＮＤ」）、１，１，３，３－テトラメチルブチルパーオキシネオデカノエート（同「パーオクタＮＤ」）、ｔ－ヘキシルパーオキシネオデカノエート（同「パーヘキシルＮＤ」）、ｔ－ブチルパーオキシネオデカノエート（同「パーブチルＮＤ」）、ｔ－ブチルパーオキシネオヘプタノエート（同「パーブチルＮＨＰ」）、ｔ－ヘキシルパーオキシピバレート（同「パーヘキシルＰＶ」）、ｔ－ブチルパーオキシピバレート（同「パーブチルＰＶ」）、２，５－ジメチル－２，５－ジ（２－エチルヘキサノイル）ヘキサン（同「パーヘキサ２５０」）、１，１，３，３－テトラメチルブチルパーオキシ－２－エチルヘキサノエート（同「パーオクタＯ」）、ｔ－ヘキシルパーオキシ－２－エチルヘキサノエート（同「パーヘキシルＯ」）、ｔ－ブチルパーオキシ－２－エチルヘキサノエート（同「パーブチルＯ」）、ｔ－ブチルパーオキシラウレート（同「パーブチルＬ」）、ｔ－ブチルパーオキシ－３，５，５－トリメチルヘキサノエート（同「パーブチル３５５」）、ｔ－ヘキシルパーオキシイソプロピルモノカーボネート（同「パーヘキシルＩ」）、ｔ－ブチルパーオキシイソプロピルモノカーボネート（同「パーブチルＩ」）、ｔ－ブチルパーオキシ－２－エチルヘキシルモノカーボネート（同「パーブチルＥ」）、ｔ－ブチルパーオキシアセテート（同「パーブチルＡ」）、ｔ－ヘキシルパーオキシベンゾエート（同「パーヘキシルＺ」）及びｔ－ブチルパーオキシベンゾエート（同「パーブチルＺ」）等が挙げられ、これらの内の１種又は２種以上を用いることができる。 Examples of the organic peroxide include 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (trade name “Pertetra A” manufactured by NOF CORPORATION), 1,1-di (t- Hexylperoxy) cyclohexane (the same “Perhexa HC”), 1,1-di (t-butylperoxy) cyclohexane (the same “Perhexa C”), n-butyl-4,4-di (t-butylperoxy) Valerate (the same "Perhexa V"), 2,2-di (t-butylperoxy) butane (the same "Perhexa 22"), t-butyl hydroperoxide (the same "Perbutyl H"), cumene hydroperoxide (Japan Oil company, trade name "Park Mill H"), 1,1,3,3-tetramethylbutyl hydroperoxide (the same "Per octa H"), t-butyl cumyl peroxide (the same) Perbutyl C ”), di-t-butyl peroxide (the same“ perbutyl D ”), di-t-hexyl peroxide (the same“ perhexyl D ”), di (3,5,5-trimethylhexanoyl) peroxide ( "Perloyl 355"), dilauroyl peroxide ("Perloyl L"), bis (4-t-butylcyclohexyl) peroxydicarbonate ("Perloyl TCP"), di-2-ethylhexyl peroxydicarbonate ( "Perloyl OPP"), di-sec-butyl peroxydicarbonate ("Perloyl SBP"), cumyl peroxyneodecanoate ("Perkyl ND"), 1,1,3,3-tetramethylbutyl Peroxyneodecanoate (same as "Perocta ND"), t-hexyl peroxyneodeca Ate (the same “perhexyl ND”), t-butyl peroxy neodecanoate (the same “perbutyl ND”), t-butyl peroxy neoheptanoate (the same “perbutyl NHP”), t-hexyl peroxypivalate (The same "Perhexyl PV"), t-butyl peroxypivalate (the same "Perbutyl PV"), 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane (the same "Perhexa 250"), 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexanoate (the same "Perocta O"), t-hexyl peroxy-2-ethylhexanoate (the same "Perhexyl O"), t- Butyl peroxy-2-ethylhexanoate (the same "perbutyl O"), t-butyl peroxylaurate (the same "perbutyl L"), t-bu Cylperoxy-3,5,5-trimethylhexanoate (the same "Perbutyl 355"), t-hexyl peroxyisopropyl monocarbonate (the same "Perhexyl I"), t-butyl peroxyisopropyl monocarbonate (the same "Perbutyl I") ), T-butylperoxy-2-ethylhexyl monocarbonate (the same “perbutyl E”), t-butyl peroxyacetate (the same “perbutyl A”), t-hexyl peroxybenzoate (the same “perhexyl Z”) and t -Butyl peroxybenzoate (the same "perbutyl Z") and the like, and one or more of them can be used.
　上記無機過酸化物としては、過硫酸カリウム、過硫酸ナトリウム、過硫酸アンモニウム等が挙げられる。また、レドックス開始の場合、亜硫酸ナトリウム、チオ硫酸ナトリウム、ナトリウムホルムアルデヒドスルホキシレート、アスコルビン酸、亜硫酸ガス（ＳＯ2）、硫酸第一鉄等を還元剤として用いることができる。 Examples of the inorganic peroxide include potassium persulfate, sodium persulfate, ammonium persulfate and the like. In the case of redox initiation, sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, sulfurous acid gas (SO 2 ), ferrous sulfate, etc. can be used as a reducing agent.
　重合開始剤の好ましい使用量は、用いる単量体の総量を１００質量部としたときに、例えば、０．００１～２質量部であり、また例えば、０．００５～１質量部であり、また例えば、０．０１～０．１質量部である。重合開始剤の使用量が０．００１質量部以上であれば重合反応を安定的に行うことができ、２質量部以下であれば一次鎖長の長い重合体を得やすい。 The preferred amount of the polymerization initiator used is, for example, 0.001 to 2 parts by mass, or 0.005 to 1 part by mass, when the total amount of the monomers used is 100 parts by mass. For example, it is 0.01 to 0.1 part by mass. When the amount of the polymerization initiator used is 0.001 part by mass or more, the polymerization reaction can be stably carried out, and when it is 2 parts by mass or less, a polymer having a long primary chain length can be easily obtained.
＜重合温度等＞
　重合温度は、使用する単量体の種類及び濃度等の条件にもよるが、０～１００℃が好ましく、２０～８０℃がより好ましい。重合温度は一定であってもよいし、重合反応の期間において変化するものであってもよい。また、重合時間は１分間～２０時間が好ましく、１時間～１０時間がより好ましい。 <Polymerization temperature, etc.>
The polymerization temperature is preferably 0 to 100 ° C., more preferably 20 to 80 ° C., though it depends on conditions such as the type and concentration of the monomer used. The polymerization temperature may be constant or may change during the period of the polymerization reaction. The polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
＜乾燥工程等＞
　乾燥工程に先立って、未反応単量体又はその塩、開始剤由来の不純物等を除去する目的で、重合工程に引き続き、遠心分離及びろ過等の固液分離工程、水、メタノール、アセトニトリル又は重合溶媒と同一の溶媒等を用いた洗浄工程を備えることが好ましい。上記洗浄工程を備えた場合、本重合体が二次凝集した場合であっても、使用時に解れやすく、さらに残存する未反応単量体が除去されることにより、結着性や電池特性の点でも有利である。 <Drying process, etc.>
Prior to the drying step, for the purpose of removing unreacted monomers or salts thereof, impurities derived from the initiator, etc., following the polymerization step, a solid-liquid separation step such as centrifugation and filtration, water, methanol, acetonitrile or polymerization. It is preferable to include a washing step using the same solvent as the solvent. When the above washing step is provided, even when the present polymer is secondarily aggregated, it is easy to unravel during use, and the remaining unreacted monomer is removed, so that the binding property and the battery characteristics are improved. But it is advantageous.
＜中和工程＞
　本製造方法では、エチレン性不飽和カルボン酸単量体として未中和又は部分中和塩を用いた場合、重合工程により得られた重合体分散液にアルカリ性化合物を添加して重合体を中和（以下、「工程中和」ともいう）する工程を実施した後、既述の乾燥工程で溶媒を除去して固体状態の本重合体を得てもよい。また、未中和若しくは部分中和塩状態のまま乾燥工程を実施して粉末等の固体状態の本重合体を得た後、電極合剤層スラリーを調製する際に塩を形成するためのアルカリ化合物を添加して、重合体を中和（以下、「後中和」ともいう）する工程を実施してもよい。上記の内、工程中和の方が、二次凝集体が解れやすい傾向にあり好ましい。 <Neutralization process>
In the present production method, when an unneutralized or partially neutralized salt is used as the ethylenically unsaturated carboxylic acid monomer, an alkaline compound is added to the polymer dispersion obtained by the polymerization step to neutralize the polymer. After performing the step (hereinafter, also referred to as "step neutralization"), the solvent may be removed in the above-mentioned drying step to obtain the solid state polymer. Further, after the drying step is carried out in the unneutralized or partially neutralized salt state to obtain a solid state main polymer such as powder, an alkali for forming a salt when preparing the electrode mixture layer slurry. A step of adding a compound to neutralize the polymer (hereinafter, also referred to as “post-neutralization”) may be carried out. Of the above, the step neutralization is preferable because the secondary aggregate tends to be easily loosened.
　工程中和などの中和工程において用いることができるアルカリ性化合物は、特に限定されないが、既に説明した、重合工程において用いうる各種のアルカリ性化合物を用いることができる。例えば、ＬｉＯＨ、ＮａＯＨ、ＫＯＨ、炭酸ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸水素カリウム等が挙げられる。Ｌｉ塩を用いた場合の電池性能の観点から、本重合体のＬｉ塩が得られる、ＬｉＯＨが好適である。 The alkaline compound that can be used in the neutralization step such as the step neutralization is not particularly limited, but various alkaline compounds that can be used in the polymerization step described above can be used. For example, LiOH, NaOH, KOH, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like can be mentioned. From the viewpoint of battery performance when a Li salt is used, LiOH is preferable because it gives the Li salt of the present polymer.
＜二次電池電極用組成物及びその製造方法＞
　本組成物は、二次電池の電極（合剤層）用の組成物であり、本重合体を含有するバインダー、活物質及び水を含むことができる。本組成物における本重合体の使用量は、活物質の全量に対して、例えば、０．１質量％以上２０質量％以下である。上記使用量は、また例えば、０．２質量％以上１０質量％以下であり、また例えば０．３質量％以上８質量％以下であり、また例えば０．４質量％以上５質量％以下である。本重合体及びその塩の使用量が０．１質量％未満の場合、十分な結着性が得られないことがある。また、活物質等の分散安定性が不十分となり、形成される合剤層の均一性が低下する場合がある。一方、本重合体及びその塩の使用量が２０質量％を超える場合、電極合剤層組成物が高粘度となり集電体への塗工性が低下することがある。その結果、得られた合剤層にブツや凹凸が生じて電極特性に悪影響を及ぼす虞がある。 <Composition for Secondary Battery Electrode and Manufacturing Method Thereof>
The composition is a composition for an electrode (mixture layer) of a secondary battery, and can contain a binder containing the polymer, an active material, and water. The amount of the present polymer used in the present composition is, for example, 0.1% by mass or more and 20% by mass or less based on the total amount of the active material. The amount used is, for example, 0.2% by mass or more and 10% by mass or less, for example 0.3% by mass or more and 8% by mass or less, and for example 0.4% by mass or more and 5% by mass or less. .. When the amount of the present polymer and its salt used is less than 0.1% by mass, sufficient binding property may not be obtained. In addition, the dispersion stability of the active material and the like becomes insufficient, which may reduce the uniformity of the formed mixture layer. On the other hand, when the amount of the present polymer and its salt used exceeds 20% by mass, the composition of the electrode mixture layer may have a high viscosity and the coatability on the current collector may be deteriorated. As a result, the obtained mixture layer may have bumps or irregularities, which may adversely affect the electrode characteristics.
　なお、本明細書によれば、本重合体の準備工程と、本重合体を用いて本組成物を調製する工程と、を備える、二次電池電極用組成物の製造方法も提供される。 The present specification also provides a method for producing a composition for a secondary battery electrode, which comprises a step of preparing the present polymer and a step of preparing the present composition using the present polymer.
　本重合体及びその塩の使用量が上記範囲内であれば、スラリー粘度が十分に低い本組成物が得られるとともに、集電体への密着性ひいては合剤層の結着性が極めて高い合剤層を得ることができ、結果として電池の耐久性が向上する。さらに、本重合体及びその塩は、活物質に対して少量（例えば５質量％以下）でも十分高い結着性を示し、かつ、カルボキシアニオンを有することから、界面抵抗が小さく、ハイレート特性に優れた電極が得られる。 When the amount of the present polymer and its salt used is within the above range, the present composition having a sufficiently low slurry viscosity can be obtained, and the adhesiveness to the current collector and thus the binding property of the mixture layer are extremely high. The agent layer can be obtained, and as a result, the durability of the battery is improved. Further, the present polymer and its salt exhibit a sufficiently high binding property with respect to the active material even in a small amount (for example, 5% by mass or less), and since they have a carboxy anion, they have low interfacial resistance and excellent high rate characteristics. The electrode is obtained.
　上記活物質の内、正極活物質としては主に遷移金属酸化物のリチウム塩が用いられ、例えば、層状岩塩型及びスピネル型のリチウム含有金属酸化物を使用することができる。層状岩塩型の正極活物質の具体的な化合物としては、コバルト酸リチウム、ニッケル酸リチウム、並びに、三元系と呼ばれるＮＣＭ｛Ｌｉ（Ｎｉx，Ｃｏy，Ｍｎz）、ｘ＋ｙ＋ｚ＝１｝及びＮＣＡ｛Ｌｉ（Ｎｉ1-a-bＣｏaＡｌb）｝等が挙げられる。また、スピネル型の正極活物質としてはマンガン酸リチウム等が挙げられる。酸化物以外にもリン酸塩、ケイ酸塩及び硫黄等が使用され、リン酸塩としては、オリビン型のリン酸鉄リチウム等が挙げられる。正極活物質としては、上記のうちの１種を単独で使用してもよく、２種以上を組み合わせて混合物又は複合物として使用してもよい。 Of the above active materials, a lithium salt of a transition metal oxide is mainly used as the positive electrode active material, and for example, layered rock salt type and spinel type lithium-containing metal oxides can be used. Specific compounds of the positive electrode active material of layered rock-salt, lithium cobaltate, lithium nickelate, and, NCM {Li (Ni x, Co y, Mn z), x + y + z = 1} called ternary and NCA Examples include {Li (Ni 1-ab Co a Al b )} and the like. Examples of the spinel-type positive electrode active material include lithium manganate. In addition to oxides, phosphates, silicates, sulfur, and the like are used. Examples of phosphates include olivine-type lithium iron phosphate. As the positive electrode active material, one of the above may be used alone, or two or more of them may be used in combination as a mixture or composite.
　尚、層状岩塩型のリチウム含有金属酸化物を含む正極活物質を水に分散させた場合、活物質表面のリチウムイオンと水中の水素イオンとが交換されることにより、分散液がアルカリ性を示す。このため、一般的な正極用集電体材料であるアルミ箔（Ａｌ）等が腐食される虞がある。このような場合には、バインダーとして未中和又は部分中和された本重合体を用いることにより、活物質から溶出するアルカリ分を中和することが好ましい。また、未中和又は部分中和された本重合体の使用量は、本重合体の中和されていないカルボキシ基量が活物質から溶出するアルカリ量に対して当量以上となるように用いることが好ましい。 Note that when a positive electrode active material containing a layered rock salt type lithium-containing metal oxide is dispersed in water, the lithium ions on the surface of the active material and hydrogen ions in the water are exchanged, so that the dispersion liquid shows alkaline. Therefore, aluminum foil (Al), which is a general positive electrode current collector material, may be corroded. In such a case, it is preferable to neutralize the alkali component eluted from the active material by using the unneutralized or partially neutralized main polymer as the binder. The amount of the unneutralized or partially neutralized polymer used is such that the amount of unneutralized carboxy groups of the polymer is equivalent to or more than the amount of alkali eluted from the active material. Is preferred.
　正極活物質はいずれも電気伝導性が低いため、導電助剤を添加して使用されるのが一般的である。導電助剤としては、カーボンブラック、カーボンナノチューブ、カーボンファイバー、黒鉛微粉、炭素繊維等の炭素系材料が挙げられ、これらの内、優れた導電性を得やすい点からカーボンブラック、カーボンナノチューブ及びカーボンファイバー、が好ましい。また、カーボンブラックとしては、ケッチェンブラック及びアセチレンブラックが好ましい。導電助剤は、上記の１種を単独で使用してもよく、２種以上を組み合わせて使用してもよい。導電助剤の使用量は、導電性とエネルギー密度を両立するという観点から活物質の全量に対して、例えば、０．２～２０質量％とすることができ、また例えば、０．２～１０質量％とすることができる。また正極活物質は導電性を有する炭素系材料で表面コーティングしたものを使用してもよい。 Since all positive electrode active materials have low electrical conductivity, they are generally used with a conductive additive added. Examples of the conductive aid include carbon-based materials such as carbon black, carbon nanotubes, carbon fibers, graphite fine powder, and carbon fibers. Among them, carbon black, carbon nanotubes, and carbon fibers are easy to obtain excellent conductivity. , Are preferred. Moreover, as the carbon black, Ketjen black and acetylene black are preferable. As the conductive auxiliary agent, one type described above may be used alone, or two or more types may be used in combination. The amount of the conductive auxiliary agent used can be, for example, 0.2 to 20% by mass based on the total amount of the active material from the viewpoint of achieving both conductivity and energy density. It can be mass%. Further, as the positive electrode active material, a surface-coated carbon-based material having conductivity may be used.
　一方、負極活物質としては、例えば炭素系材料、リチウム金属、リチウム合金及び金属酸化物等が挙げられ、これらの内の１種又は２種以上を組み合わせて用いることができる。これらの内でも、天然黒鉛、人造黒鉛、ハードカーボン及びソフトカーボン等の炭素系材料からなる活物質（以下、「炭素系活物質」ともいう）が好ましく、天然黒鉛及び人造黒鉛等の黒鉛、並びにハードカーボンがより好ましい。また、黒鉛の場合、電池性能の面から球形化黒鉛が好適に用いられ、その粒子サイズの好ましい範囲は、例えば、１～２０μｍであり、また例えば、５～１５μｍである。また、エネルギー密度を高くするために、ケイ素やスズなどのリチウムを吸蔵できる金属又は金属酸化物等を負極活物質として使用することもできる。その中でも、ケイ素は黒鉛に比べて高容量であり、ケイ素、ケイ素合金及び一酸化ケイ素（ＳｉＯ）等のケイ素酸化物のようなケイ素系材料からなる活物質（以下、「ケイ素系活物質」ともいう）を用いることができる。しかし、上記ケイ素系活物質は高容量である反面充放電に伴う体積変化が大きい。このため、上記炭素系活物質と併用するのが好ましい。この場合、ケイ素系活物質の配合量が多いと電極材料の崩壊を招き、サイクル特性（耐久性）が大きく低下する場合がある。このような観点から、ケイ素系活物質を併用する場合、その使用量は炭素系活物質に対して、例えば、６０質量％以下であり、また例えば、３０質量％以下である。 On the other hand, examples of the negative electrode active material include carbon-based materials, lithium metals, lithium alloys, metal oxides, and the like, and one or more of these may be used in combination. Among these, active materials composed of carbon-based materials such as natural graphite, artificial graphite, hard carbon and soft carbon (hereinafter, also referred to as “carbon-based active material”) are preferable, and graphite such as natural graphite and artificial graphite, and Hard carbon is more preferred. In the case of graphite, spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferable particle size range is, for example, 1 to 20 μm and, for example, 5 to 15 μm. Further, in order to increase the energy density, a metal or metal oxide capable of occluding lithium such as silicon or tin can be used as the negative electrode active material. Among them, silicon has a higher capacity than graphite, and active materials made of silicon-based materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter, also referred to as “silicon-based active material”). Can be used. However, the above silicon-based active material has a high capacity, but on the other hand, the volume change due to charge and discharge is large. Therefore, it is preferable to use the carbon-based active material together. In this case, if the amount of the silicon-based active material added is large, the electrode material may be collapsed, and the cycle characteristics (durability) may be significantly reduced. From such a point of view, when the silicon-based active material is used in combination, the amount thereof is, for example, 60% by mass or less, and for example, 30% by mass or less, based on the carbon-based active material.
　本重合体を含むバインダーは、本重合体がエチレン性不飽和カルボン酸単量体に由来する構造単位（（ａ）成分）を有する。ここで、（ａ）成分はケイ素系活物質に対する親和性が高く、良好な結着性を示す。このため、本バインダーはケイ素系活物質を含む高容量タイプの活物質を用いた場合にも優れた結着性を示すことから、得られる電極の耐久性向上に対しても有効であるものと考えられる。 The binder containing the present polymer has a structural unit (component (a)) in which the present polymer is derived from an ethylenically unsaturated carboxylic acid monomer. Here, the component (a) has a high affinity for the silicon-based active material and exhibits a good binding property. Therefore, the present binder exhibits excellent binding properties even when a high-capacity type active material containing a silicon-based active material is used, and thus is also effective for improving the durability of the obtained electrode. Conceivable.
　炭素系活物質は、それ自身が良好な電気伝導性を有するため、必ずしも導電助剤を添加する必要はない。抵抗をより低減する等の目的で導電助剤を添加する場合、エネルギー密度の観点からその使用量は活物質の総量に対して、例えば、１０質量％以下であり、また例えば、５重量％以下である。 Since the carbon-based active material itself has good electrical conductivity, it is not always necessary to add a conductive auxiliary agent. When a conductive auxiliary agent is added for the purpose of further reducing resistance, the amount used is, for example, 10% by mass or less and 5% by weight or less, based on the total amount of the active material, from the viewpoint of energy density. Is.
　本組成物がスラリー状態の場合、活物質の使用量は、本組成物全量に対して、例えば、１０～７５質量％の範囲であり、また例えば、３０～６５質量％の範囲である。活物質の使用量が１０質量％以上であればバインダー等のマイグレーションが抑えられるとともに、媒体の乾燥コストの面でも有利となる。一方、７５質量％以下であれば本組成物の流動性及び塗工性を確保することができ、均一な合剤層を形成することができる。 When the composition is in a slurry state, the amount of the active material used is in the range of, for example, 10 to 75% by mass, or in the range of 30 to 65% by mass, based on the total amount of the composition. When the amount of the active material used is 10% by mass or more, migration of the binder and the like can be suppressed, and it is also advantageous in terms of medium drying cost. On the other hand, when the content is 75% by mass or less, the fluidity and coatability of the composition can be secured, and a uniform mixture layer can be formed.
　また、湿粉状態で本組成物を調製する場合、活物質の使用量は、本組成物全量に対して、例えば、６０～９７質量％の範囲であり、また例えば、７０～９０質量％の範囲である。また、エネルギー密度の観点から、バインダーや導電助剤等の活物質以外の不揮発成分は、必要な結着性や導電性が担保される範囲内で出来る限り少ない方がよい。 When the present composition is prepared in a wet powder state, the amount of the active material used is in the range of, for example, 60 to 97% by mass, or 70 to 90% by mass, based on the total amount of the present composition. It is a range. From the viewpoint of energy density, it is preferable that the amount of non-volatile components other than the active material such as the binder and the conductive additive be as small as possible within the range in which the required binding property and conductivity are ensured.
　本組成物は、媒体として水を使用する。また、本組成物の性状及び乾燥性等を調整する目的で、メタノール及びエタノール等の低級アルコール類、エチレンカーボネート等のカーボネート類、アセトン等のケトン類、テトラヒドロフラン、Ｎ－メチルピロリドン等の水溶性有機溶剤との混合溶媒としてもよい。混合媒体中の水の割合は、例えば、５０質量％以上であり、また例えば、７０質量％以上である。 The composition uses water as a medium. For the purpose of adjusting the properties and drying properties of the composition, lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, water-soluble organic compounds such as tetrahydrofuran and N-methylpyrrolidone. It may be a mixed solvent with a solvent. The proportion of water in the mixed medium is, for example, 50% by mass or more and, for example, 70% by mass or more.
　本組成物を塗工可能なスラリー状態とする場合、組成物全体に占める水を含む媒体の含有量は、スラリーの塗工性、および乾燥に必要なエネルギーコスト、生産性の観点から、例えば、２５～９０質量％の範囲とすることができ、また例えば、３５～７０質量％とすることができる。また、プレス可能な湿粉状態とする場合、上記媒体の含有量はプレス後の合剤層の均一性の観点から、例えば、３～４０質量％の範囲とすることができ、また例えば、１０～３０質量％の範囲とすることができる。 When the present composition is in a coatable slurry state, the content of the medium containing water in the entire composition is the coatability of the slurry, and the energy cost required for drying, from the viewpoint of productivity, for example, The amount can be in the range of 25 to 90% by mass, and can be, for example, 35 to 70% by mass. In addition, in the case of a wettable powder that can be pressed, the content of the medium can be, for example, in the range of 3 to 40% by mass from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of up to 30% by mass.
　なお、本組成物に含まれるバインダー成分は、本重合体のみからなるものであってもよいが、これ以外にもスチレン／ブタジエン系ラテックス（ＳＢＲ）、アクリル系ラテックス及びポリフッ化ビニリデン系ラテックス等の他のバインダー成分を併用してもよい。他のバインダー成分を併用する場合、その使用量は、活物質に対して、例えば、０．１～５質量％以下とすることができ、また例えば、０．１～２質量％以下とすることができ、また例えば、０．１～１質量％以下とすることができる。他のバインダー成分の使用量が５質量％を超えると抵抗が増大し、ハイレート特性が不十分なものとなる場合がある。上記の中でも、結着性及び耐屈曲性のバランスに優れる点で、スチレン／ブタジエン系ラテックスが好ましい。 The binder component contained in the composition may be composed only of the polymer, but in addition to this, a styrene / butadiene latex (SBR), an acrylic latex, a polyvinylidene fluoride latex, or the like. You may use together other binder components. When the other binder component is used in combination, the amount thereof can be, for example, 0.1 to 5% by mass or less, and for example, 0.1 to 2% by mass or less, based on the active material. And can be, for example, 0.1 to 1% by mass or less. If the amount of the other binder component used exceeds 5% by mass, the resistance may increase and the high rate property may become insufficient. Among the above, a styrene / butadiene-based latex is preferable because it has an excellent balance of binding property and flex resistance.
　本組成物は、上記の活物質、水及びバインダーを必須の構成成分とするものであり、公知の手段を用いて各成分を混合することにより得られる。各成分の混合方法は特段制限されるものではなく、公知の方法を採用することができるが、活物質、導電助剤及びバインダーである本重合体等の粉末成分をドライブレンドした後、水等の分散媒と混合し、分散混練する方法が好ましい。本組成物をスラリー状態で得る場合、分散不良や凝集のないスラリーに仕上げることが好ましい。混合手段としては、プラネタリーミキサー、薄膜旋回式ミキサー及び自公転式ミキサー等の公知のミキサーを使用することができるが、短時間で良好な分散状態が得られる点で薄膜旋回式ミキサーを使用して行うことが好ましい。また、薄膜旋回式ミキサーを用いる場合は、予めディスパー等の攪拌機で予備分散を行うことが好ましい。 The present composition has the above-mentioned active material, water and binder as essential constituent components, and can be obtained by mixing the components using a known means. The mixing method of each component is not particularly limited, and a known method can be adopted. After dry blending the powder components such as the active material, the conductive auxiliary agent and the polymer as a binder, water, etc. The method of mixing with the dispersion medium of (1) and dispersing and kneading is preferable. When the present composition is obtained in the form of a slurry, it is preferable to finish it into a slurry free from poor dispersion and aggregation. As the mixing means, a known mixer such as a planetary mixer, a thin film swirling mixer and a revolving mixer can be used, but a thin film swirling mixer is used in that a good dispersion state can be obtained in a short time. It is preferable to carry out. When a thin film swirling mixer is used, it is preferable to carry out preliminary dispersion with a stirrer such as a disper in advance.
　本組成物のスラリーの粘度は、２５℃におけるせん断速度６０ｓ-1のずり粘度として、例えば、５００～１００，０００ｍＰａ・ｓの範囲とすることができ、また例えば、１，０００～５０，０００ｍＰａ・ｓの範囲とすることができる。また例えば、本組成物のスラリー粘度は、５００～１０，０００ｍＰａ・ｓの範囲であることが好ましく、より好ましくは、同５００～７，０００ｍＰａ・ｓ、さらに好ましくは、同５００～６，０００ｍＰａ・ｓとすることができ、なお好ましくは同５００～５，０００ｍＰａ・ｓとすることが、一層好ましくは同５００～４，０００ｍＰａ・ｓとすることができ、より一層好ましくは同５００～３，０００ｍＰａ・ｓとすることができ、さらに一層好ましくは同５００～２，０００ｍＰａ・ｓとすることができ、なお一層好ましくは同５００～１，８００ｍＰａ・ｓ、また好ましくは、同５００～１，７００ｍＰａ・ｓとすることができ、また好ましくは同５００～１，６００ｍＰａ・ｓであり、また好ましくは同５００～１，５００ｍＰａ・ｓである。 The viscosity of the slurry of the present composition can be in the range of, for example, 500 to 100,000 mPa · s as a shear viscosity at a shear rate of 60 s −1 at 25 ° C., and can be, for example, 1,000 to 50,000 mPa · s. It can be in the range of s. Further, for example, the slurry viscosity of the present composition is preferably in the range of 500 to 10,000 mPa · s, more preferably 500 to 7,000 mPa · s, and further preferably 500 to 6,000 mPa · s. s, more preferably 500 to 5,000 mPa · s, still more preferably 500 to 4,000 mPa · s, still more preferably 500 to 3,000 mPa · s. .S, more preferably 500 to 2,000 mPas, still more preferably 500 to 1,800 mPas, and still more preferably 500 to 1,700 mPas. s, preferably 500 to 1,600 mPa · s, and more preferably 500 to 1,500 m. It is a · s.
　一方、本組成物を湿粉状態で得る場合、ヘンシェルミキサー、ブレンダ―、プラネタリーミキサー及び２軸混練機等を用いて、濃度ムラのない均一な状態まで混練することが好ましい。 On the other hand, when the composition is obtained in a wet powder state, it is preferable to use a Henschel mixer, a blender, a planetary mixer, a twin-screw kneader or the like to knead the mixture to a uniform state without unevenness in concentration.
＜二次電池電極＞
　本電極は、銅又はアルミニウム等の集電体表面に本組成物から形成される合剤層を備えてなるものである。合剤層は、集電体の表面に本組成物を塗工した後、水等の媒体を乾燥除去することにより形成される。本組成物を塗工する方法は特に限定されず、ドクターブレード法、ディップ法、ロールコート法、コンマコート法、カーテンコート法、グラビアコート法及びエクストルージョン法などの公知の方法を採用することができる。また、上記乾燥は、温風吹付け、減圧、（遠）赤外線、マイクロ波照射等の公知の方法により行うことができる。通常、乾燥後に得られた合剤層には、金型プレス及びロールプレス等による圧縮処理が施される。圧縮することにより活物質及びバインダーを密着させ、合剤層の強度及び集電体への密着性を向上させることができる。圧縮により合剤層の厚みを、例えば、圧縮前の３０～８０％程度に調整することができ、圧縮後の合剤層の厚みは４～２００μｍ程度が一般的である。 <Secondary battery electrode>
The present electrode comprises a mixture layer formed of the present composition on the surface of a current collector such as copper or aluminum. The mixture layer is formed by applying the present composition on the surface of the current collector and then removing a medium such as water by drying. The method of applying the present composition is not particularly limited, and a known method such as a doctor blade method, a dip method, a roll coating method, a comma coating method, a curtain coating method, a gravure coating method and an extrusion method may be adopted. it can. Further, the drying can be performed by a known method such as blowing hot air, reducing pressure, (far) infrared rays, or microwave irradiation. Usually, the mixture layer obtained after drying is subjected to compression treatment by a die press, a roll press or the like. By compressing, the active material and the binder can be brought into close contact, and the strength of the mixture layer and the adhesion to the current collector can be improved. The thickness of the mixture layer can be adjusted to, for example, about 30 to 80% before compression by compression, and the thickness of the mixture layer after compression is generally about 4 to 200 μm.
　なお、本明細書によれば、本重合体の準備工程と、本重合体を用いて本組成物を調製する工程と、本組成物を用いて二次電池電極を調製する工程と、を備える、二次電池電極の製造方法も提供される。 According to the present specification, the present invention includes a step of preparing the present polymer, a step of preparing the present composition using the present polymer, and a step of preparing a secondary battery electrode using the present composition. A method for manufacturing a secondary battery electrode is also provided.
　本電極にセパレータ及び非水電解液を備えることにより、二次電池を作製することができる。セパレータは電池の正極及び負極間に配され、両極の接触による短絡の防止や電解液を保持してイオン導電性を確保する役割を担う。セパレータにはフィルム状の絶縁性微多孔膜であって、良好なイオン透過性及び機械的強度を有するものが好ましい。具体的な素材としては、ポリエチレン及びポリプロピレン等のポリオレフィン、ポリテトラフルオロエチレン等を使用することができる。 By providing this electrode with a separator and a non-aqueous electrolyte, a secondary battery can be manufactured. The separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of preventing a short circuit due to contact between both electrodes and holding an electrolytic solution to ensure ionic conductivity. The separator is preferably a film-like insulating microporous film having good ion permeability and mechanical strength. As a specific material, polyolefin such as polyethylene and polypropylene, polytetrafluoroethylene, or the like can be used.
　非水電解液は、二次電池に一般的に使用される公知のものを用いることができる。具体的な溶媒としては、プロピレンカーボネート及びエチレンカーボネート等の高誘電率で電解質の溶解能力の高い環状カーボネート、並びに、エチルメチルカーボネート、ジメチルカーボネート及びジエチルカーボネート等の粘性の低い鎖状カーボネート等が挙げられ、これらを単独で又は混合溶媒として使用することができる。非水電解液は、これらの溶媒にＬｉＰＦ6、ＬｉＳｂＦ6、ＬｉＢＦ4、ＬｉＣｌＯ4、ＬｉＡｌＯ4等のリチウム塩を溶解して使用される。二次電池は、セパレータで仕切られた正極板及び負極板を渦巻き状又は積層構造にしてケース等に収納することにより得られる。 As the non-aqueous electrolyte, a known one generally used for secondary batteries can be used. Specific solvents include cyclic carbonates having high permittivity and high electrolyte dissolving ability such as propylene carbonate and ethylene carbonate, and low-viscosity chain carbonates such as ethylmethyl carbonate, dimethyl carbonate and diethyl carbonate. , And these can be used alone or as a mixed solvent. The non-aqueous electrolytic solution is used by dissolving a lithium salt such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , and LiAlO 4 in these solvents. The secondary battery is obtained by accommodating a positive electrode plate and a negative electrode plate, which are partitioned by a separator, in a spiral or laminated structure in a case or the like.
　以上説明したように、本明細書に開示される二次電池電極用バインダーは、優れた結着性と合剤層スラリーの粘度低下とを両立することができる。上記バインダーを使用して得られた電極を備えた二次電池は、良好な一体性を確保でき、充放電を繰り返しても良好な耐久性（サイクル特性）を示すと予想され、例えば、車載用二次電池等に好適である。 As described above, the binder for secondary battery electrodes disclosed in the present specification can achieve both excellent binding properties and reduction in viscosity of the mixture layer slurry. A secondary battery provided with an electrode obtained by using the above binder is expected to be able to secure good integrity and to exhibit good durability (cycle characteristics) even after repeated charge and discharge. It is suitable for secondary batteries and the like.
　以下、本明細書に開示される本重合体の製造及び使用について具体的に例示して説明するが、本明細書の開示は、以下の実施例に限定されるものではない。また、以下において、特に断りの無い限り、「部」及び「％」は、特に断りの無い限り、質量部及び質量％を意味するものとする。 Hereinafter, the production and use of the present polymer disclosed in the present specification will be specifically illustrated and described, but the disclosure of the present specification is not limited to the following examples. Further, in the following, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified, unless otherwise specified.
＜本重合体の製造例＞
＜製造例１：架橋重合体塩Ｒ－１の製造＞
　重合には、攪拌翼、温度計、還流冷却器及び窒素導入管を備えた反応器を用いた。反応器内にアセトニトリル５６７部、イオン交換水２．２０部、アクリル酸（以下、「ＡＡ」という）１００部、２－ヒドロキシ－３－アクリロイロキシプロピルメタクリレート（共栄社化学社製、ライトエステルＧ－２０１Ｐ）０．２０部及び上記ＡＡに対して１．０モル％に相当するトリエチルアミンを仕込んだ。反応器内を十分に窒素置換した後、加温して内温を５５℃まで昇温した。内温が５５℃で安定したことを確認した後、重合開始剤として２，２’－アゾビス（２，４－ジメチルバレロニトリル）（和光純薬工業社製、商品名「Ｖ－６５」）０．０４０部を添加したところ、反応液に白濁が認められたため、この点を重合開始点とした。単量体濃度は１５．０％と算出された。 <Production Example of the Polymer>
<Production Example 1: Production of crosslinked polymer salt R-1>
For the polymerization, a reactor equipped with a stirring blade, a thermometer, a reflux condenser and a nitrogen introduction tube was used. 567 parts of acetonitrile, 2.20 parts of ion-exchanged water, 100 parts of acrylic acid (hereinafter referred to as “AA”), 2-hydroxy-3-acryloyloxypropyl methacrylate (Kyoeisha Chemical Co., Ltd., light ester G- 201P) 0.20 part and triethylamine corresponding to 1.0 mol% based on the above AA were charged. After sufficiently replacing the inside of the reactor with nitrogen, it was heated to raise the internal temperature to 55 ° C. After confirming that the internal temperature was stable at 55 ° C., 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., trade name “V-65”) was used as a polymerization initiator. When 0.040 part was added, white turbidity was observed in the reaction solution, and this point was used as the polymerization initiation point. The monomer concentration was calculated to be 15.0%.
　外温（水バス温度）を調整して内温を５５℃に維持しながら重合反応を継続し、重合開始点から６時間経過した時点で内温を６５℃まで昇温した。内温を６５℃で維持し、反応開始点から１２時間経過した時点で反応液の冷却を開始し、内温が２５℃まで低下した後、水酸化リチウム・一水和物（以下、「ＬｉＯＨ・Ｈ２Ｏ」という）の粉末５２．５部を添加した。添加後室温下１２時間撹拌を継続して、架橋重合体塩Ｒ－１（Ｌｉ塩、中和度９０モル％）の粒子が媒体に分散したスラリー状の重合反応液を得た。 The polymerization reaction was continued while adjusting the external temperature (water bath temperature) to maintain the internal temperature at 55 ° C, and the internal temperature was raised to 65 ° C when 6 hours passed from the polymerization initiation point. The internal temperature was maintained at 65 ° C., cooling of the reaction solution was started 12 hours after the reaction start point, and after the internal temperature dropped to 25 ° C., lithium hydroxide monohydrate (hereinafter, referred to as “LiOH - 52.5 parts powder of H 2 O "hereinafter) was added. After the addition, stirring was continued for 12 hours at room temperature to obtain a slurry-like polymerization reaction liquid in which particles of the crosslinked polymer salt R-1 (Li salt, neutralization degree: 90 mol%) were dispersed in a medium.
　得られた重合反応液を遠心分離して重合体粒子を沈降させた後、上澄みを除去した。その後、重合反応液と同重量のアセトニトリルに沈降物を再分散させた後、遠心分離により重合体粒子を沈降させて上澄みを除去する操作を２回繰り返した。沈降物を回収し、減圧条件下、８０℃で３時間乾燥処理を行い、揮発分を除去することにより、架橋重合体塩Ｒ－１の粉末を得た。架橋重合体塩Ｒ－１は吸湿性を有するため、水蒸気バリア性を有する容器に密封保管した。なお、架橋重合体塩Ｒ－１の粉末をＩＲ測定し、カルボン酸のＣ＝Ｏ基由来のピークとカルボン酸ＬｉのＣ＝Ｏ由来のピークの強度比より中和度を求めたところ、仕込みからの計算値に等しく９０モル％であった。 The obtained polymerization reaction liquid was centrifuged to precipitate polymer particles, and the supernatant was removed. After that, the procedure of redispersing the precipitate in the same weight of acetonitrile as the polymerization reaction solution and then allowing the polymer particles to settle by centrifugation and removing the supernatant was repeated twice. The precipitate was recovered and dried under reduced pressure at 80 ° C. for 3 hours to remove volatile matter, thereby obtaining a powder of crosslinked polymer salt R-1. Since the cross-linked polymer salt R-1 has a hygroscopic property, it was sealed and stored in a container having a water vapor barrier property. The powder of the crosslinked polymer salt R-1 was subjected to IR measurement, and the degree of neutralization was determined from the intensity ratio of the peak derived from the C═O group of the carboxylic acid and the peak derived from the C═O of the carboxylic acid Li. 90 mol% equal to the value calculated from
＜製造例２～１５：架橋重合体塩Ｒ－２～Ｒ－１５の製造＞
　各原料の仕込み量を表１に記載の通りとした以外は製造例１と同様の操作を行い、架橋重合体塩Ｒ－２～Ｒ－１５を含む重合反応液を得た。次いで、各重合反応液について製造例１と同様の操作を行い、粉末状の架橋重合体塩Ｒ－２～Ｒ－１５を得た。各架橋重合体塩は、水蒸気バリア性を有する容器に密封保管した。尚、製造例９では、ＬｉＯＨ・Ｈ２Ｏの粉末の代わりにＮａＯＨを用いることにより、架橋重合体Ｎａ塩（中和度９０モル％）を得た。 <Production Examples 2 to 15: Production of crosslinked polymer salts R-2 to R-15>
The same operation as in Production Example 1 was carried out except that the amounts of the respective raw materials charged were as shown in Table 1 to obtain a polymerization reaction liquid containing the crosslinked polymer salts R-2 to R-15. Then, the same operation as in Production Example 1 was carried out for each polymerization reaction liquid to obtain powdery crosslinked polymer salts R-2 to R-15. Each crosslinked polymer salt was sealed and stored in a container having a water vapor barrier property. In Production Example 9, a sodium salt of a crosslinked polymer (neutralization degree: 90 mol%) was obtained by using NaOH instead of the LiOH.H 2 O powder.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　以下に、表１に示す表記について説明する。
ＡＡ：アクリル酸
ＤＭＡＡ：ジメチルアクリルアミド
ＨＡＰＭＡ：２－ヒドロキシ－３－アクリロイロキシプロピルメタクリレート（ライトエステルＧ－２０１Ｐ、共栄社化学）
ＧＤＭＡ：グリセリンジメタクリレート（ライトエステルＧ－１０１Ｐ、共栄社化学）
ＥＧＤＭＡ：二メタクリル酸エチレン（富士フィルム和光純薬）
Ｔ－２０：トリメチロールプロパンジアリルエーテル（大阪ソーダ）
ＴＥＡ：トリエチルアミン
ＡｃＣＮ：アセトニトリル
Ｖ－６５：２，２’－アゾビス（２，４－ジメチルバレロニトリル）（和光純薬工業社製） The notations shown in Table 1 will be described below.
AA: acrylic acid DMAA: dimethylacrylamide HAPMA: 2-hydroxy-3-acryloyloxypropyl methacrylate (light ester G-201P, Kyoeisha Chemical Co., Ltd.)
GDMA: glycerin dimethacrylate (light ester G-101P, Kyoeisha Chemical)
EGDMA: Ethylene dimethacrylate (Fuji Film Wako Pure Chemical)
T-20: Trimethylolpropane diallyl ether (Osaka Soda)
TEA: triethylamine AcCN: acetonitrile V-65: 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)
＜実施例＞
＜実施例１＞
　天然黒鉛１００部に粉末状の架橋重合体Ｌｉ塩Ｒ－１を３．２部秤量し、予めよく混合した後、イオン交換水１６０部を加えてディスパーで予備分散を行った後、薄膜旋回式ミキサー（プライミクス社製、ＦＭ－５６－３０）を用いて周速度２０ｍ／秒の条件で本分散を１５秒間行うことにより、スラリー状の負極合剤層組成物を得た。スラリー濃度（固形分）は、３９．２％と算出された。 <Example>
<Example 1>
3.2 parts of powdered cross-linked polymer Li salt R-1 was weighed in 100 parts of natural graphite, mixed well in advance, 160 parts of ion-exchanged water was added and predispersed with a disper, and then thin film rotation type The main dispersion was performed for 15 seconds at a peripheral speed of 20 m / sec using a mixer (FM-56-30, manufactured by Primix Co., Ltd.) to obtain a slurry negative electrode mixture layer composition. The slurry concentration (solid content) was calculated to be 39.2%.
＜電極スラリーの粘度測定＞
　上記で得られた負極合剤層組成物（スラリー）について、アントンパール社製レオメーター（Ｐｈｙｓｉｃａ ＭＣＲ３０１）を用い、ＣＰ２５－５のコーンプレート（直径２５ｍｍ、コーン角度５°）にて、２５℃におけるせん断速度６０ｓ-1のスラリー粘度を測定した。 <Viscosity measurement of electrode slurry>
The negative electrode mixture layer composition (slurry) obtained above was measured at 25 ° C. using a cone plate (diameter 25 mm, cone angle 5 °) of CP25-5 using an Anton Paar Rheometer (Physica MCR301). The slurry viscosity at a shear rate of 60 s -1 was measured.
＜９０°剥離強度（結着性）＞
　可変式アプリケーターを用いて、厚さ２０μｍの銅箔（日本製箔社製）上に上記合剤層組成物を塗布し、通風乾燥機内で１００℃×１５分間の乾燥を行うことにより合剤層を形成した。その後、合剤層の厚みが７０±５μｍ、充填密度が１．７０±０．２０ｇ／ｃｍ３になるよう圧延し、負極電極を作製した。上記で得られた負極電極を２５ｍｍ幅の短冊状に裁断した後、水平面に固定された両面テープに上記試料の合剤層面を貼付け、剥離試験用試料を作成した。試験用試料を６０℃、１晩減圧条件下で乾燥させた後、引張速度５０ｍｍ／分における９０°剥離を行い、合剤層と銅箔間の剥離強度を測定した。剥離強度は１５．８Ｎ／ｍと高く、良好であった。 <90 ° peel strength (binding property)>
Using the variable applicator, the mixture layer composition was applied onto a copper foil (manufactured by Nippon Foil Co., Ltd.) having a thickness of 20 μm, and dried at 100 ° C. for 15 minutes in a ventilation dryer to form a mixture layer. Formed. Then, the mixture layer was rolled to a thickness of 70 ± 5 μm and a packing density of 1.70 ± 0.20 g / cm 3 to prepare a negative electrode. The negative electrode obtained above was cut into a strip having a width of 25 mm, and the mixture layer surface of the above sample was attached to a double-sided tape fixed on a horizontal surface to prepare a peel test sample. After the test sample was dried under reduced pressure at 60 ° C. overnight, 90 ° peeling was performed at a pulling speed of 50 mm / min, and the peel strength between the mixture layer and the copper foil was measured. The peel strength was as high as 15.8 N / m, which was good.
＜実施例２～１５、比較例１～３＞
　活物質及びバインダーとして使用する架橋重合体塩を表２に記載の通り用いた以外は実施例１と同様の操作により負極合剤層組成物を調製した。なお、実施例３及び実施例４では、天然黒鉛及びケイ素粒子を、遊星ボールミル（ＦＲＩＴＳＣＨ社製、Ｐ－５）を用いて４００ｒｐｍで１時間撹拌し、得られた混合物に粉末状の架橋重合体Ｌｉ塩Ｒ－２を３．２部秤量し、予めよく混合した後、実施例１と同様の操作を行うことにより合剤層組成物を調製した。各合剤層組成物についてスラリー粘度及び９０°剥離強度を評価した。結果を表２に示す。 <Examples 2 to 15, Comparative Examples 1 to 3>
A negative electrode mixture layer composition was prepared in the same manner as in Example 1, except that the crosslinked polymer salt used as the active material and the binder was used as described in Table 2. In Examples 3 and 4, natural graphite and silicon particles were stirred for 1 hour at 400 rpm using a planetary ball mill (P-5, manufactured by FRITSCH), and the obtained mixture was crosslinked into powder form. 3.2 parts of Li salt R-2 was weighed and thoroughly mixed in advance, and then the same operation as in Example 1 was performed to prepare a mixture layer composition. The slurry viscosity and 90 ° peel strength of each mixture layer composition were evaluated. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示すように、２個以上の（メタ）アクリロイル基と水酸基とを有する架橋性単量体を用いた架橋重合体Ｒ－１～Ｒ－１３を用いた実施例１～１５は、合剤層スラリーの粘度が３３０～１８００ｍＰａ・ｓであり、極めて良好な粘性を示した。また、これらの実施例１～１５の剥離強度は、１４．４～１９．１Ｎ／ｍであり、十分な電極結着性を示した。これに対して、架橋していない製造例１４の重合体を用いた比較例１では、粘度が高い一方結着性が低く、アクリロイル基を２個有するが水酸基を有しない架橋性単量体を用いた製造例１５の架橋重合体を用いた比較例２では、結着性は良好であったが、スラリー粘度が依然として相当高く、アリル基を２個有し、かつ水酸基を有する架橋性単量体を用いた製造例１６の架橋重合体を用いた比較例３では、結着性が低いほか、スラリー粘度も依然高かった。 As shown in Table 2, Examples 1 to 15 using cross-linked polymers R-1 to R-13 using a cross-linkable monomer having two or more (meth) acryloyl groups and a hydroxyl group were combined. The viscosity of the agent layer slurry was 330 to 1800 mPa · s, showing extremely good viscosity. Further, the peel strengths of Examples 1 to 15 were 14.4 to 19.1 N / m, which showed sufficient electrode binding property. On the other hand, in Comparative Example 1 using the polymer of Production Example 14 which was not crosslinked, a crosslinkable monomer having high viscosity but low binding property and having two acryloyl groups but no hydroxyl group was used. In Comparative Example 2 using the crosslinked polymer of Production Example 15 used, the binding property was good, but the slurry viscosity was still considerably high, and the crosslinkable monomer having two allyl groups and having a hydroxyl group was used. In Comparative Example 3 in which the crosslinked polymer of Production Example 16 using a body was used, the binding property was low and the slurry viscosity was still high.
　以上のことから、エチレン性不飽和カルボン酸単量体と（メタ）アクリロイル基を２個有し、かつ水酸基を有する架橋性単量体とを重合して、かかる架橋性単量体に由来する架橋構造を備えることで、良好な結着性とスラリー粘度を両立できることがわかった。 From the above, the ethylenically unsaturated carboxylic acid monomer and the crosslinkable monomer having two (meth) acryloyl groups and having a hydroxyl group are polymerized to derive the crosslinkable monomer. It was found that by providing the crosslinked structure, good binding properties and slurry viscosity can both be achieved.
　また、実施例１～２、５～７によれば、架橋性単量体の使用量が非架橋性単量体１００部に対して０．１部～１０部程度で結着性の良好な架橋重合体を得ることができ、０．２部～９部、０．２部～５部、０．２部～２部、０．２部～１部程度でより結着性の良好な架橋重合体を得られることがわかった。また、架橋性単量体の使用量が、０．１～１０部程度で、十分に低いスラリー粘度の架橋重合体を得られることがわかった。 Further, according to Examples 1 to 2, 5 to 7, the amount of the crosslinkable monomer used was about 0.1 to 10 parts based on 100 parts of the non-crosslinkable monomer, and the binding property was good. It is possible to obtain a crosslinked polymer, and 0.2 parts to 9 parts, 0.2 parts to 5 parts, 0.2 parts to 2 parts, and 0.2 parts to 1 part are more suitable for forming crosslinks. It was found that a polymer could be obtained. It was also found that the amount of the crosslinkable monomer used was about 0.1 to 10 parts to obtain a crosslinked polymer having a sufficiently low slurry viscosity.
　また、実施例３～４によれば、活物質としてケイ素粒子を含有しても、安定した結着性とスラリー粘度を両立できることがわかった。さらに、実施例８によれば、製造例１～５とは構造の異なる架橋性単量体を用いた製造例６の架橋重合体を用いても、優れた結着性とスラリー粘度が得られることがわかった。 Further, according to Examples 3 to 4, it was found that even when silicon particles were included as the active material, both stable binding property and slurry viscosity could be achieved. Furthermore, according to Example 8, even when the crosslinked polymer of Production Example 6 using a crosslinkable monomer having a structure different from that of Production Examples 1 to 5 is used, excellent binding property and slurry viscosity are obtained. I understood it.
　さらにまた、実施例９～１２によれば、塩の中和度（８５％、７０％及び９０％）や中和する塩の種類（Ｌｉ，Ｎａ，Ｋ）によらず、安定した結着性とスラリー粘度を確保できることがわかった。さらに、実施例１３～１５によれば、非架橋性単量体としてジメチルアクリルアミドを用いることでも、優れた結着性とスラリー粘度を確保できることがわかった。なお、ジメチルアクリルアミドを用いることで、スラリー粘度が低くなる傾向もあった。 Furthermore, according to Examples 9 to 12, a stable binding property was obtained irrespective of the degree of neutralization of the salt (85%, 70% and 90%) and the type of salt to be neutralized (Li, Na, K). It was found that the slurry viscosity can be secured. Furthermore, according to Examples 13 to 15, it was found that excellent binding property and slurry viscosity can be secured by using dimethylacrylamide as the non-crosslinkable monomer. The slurry viscosity also tended to be lowered by using dimethylacrylamide.

Claims (6)

  1. 　架橋重合体又はその塩を有する二次電池電極バインダーであって、
    　前記架橋重合体又はその塩は、非架橋構造単位と架橋構造単位とを備え、
    前記非架橋構造単位は、エチレン性不飽和カルボン酸単量体に由来する非架橋構造単位を含み、
    　前記架橋構造単位は、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体に由来する架橋構造単位を含む、
    バインダー。     A secondary battery electrode binder having a crosslinked polymer or a salt thereof,
    The crosslinked polymer or a salt thereof comprises a non-crosslinked structural unit and a crosslinked structural unit,
    The non-crosslinked structural unit includes a non-crosslinked structural unit derived from an ethylenically unsaturated carboxylic acid monomer,
    The cross-linking structural unit has two or more (meth) acryloyl groups in one molecule, and includes a cross-linking structural unit derived from a cross-linkable monomer having a hydroxyl group,
    binder.
  2. 　前記エチレン性不飽和単量体に由来する非架橋構造単位を、前記非架橋構造単位の総量に対して３０質量％以上１００質量％以下含有する、請求項１に記載のバインダー。 The binder according to claim 1, wherein the non-crosslinked structural unit derived from the ethylenically unsaturated monomer is contained in an amount of 30% by mass or more and 100% by mass or less based on the total amount of the non-crosslinked structural unit.
  3. 　二次電池電極用組成物であって、
    　請求項１又は２に記載の二次電池電極用バインダーと、
    　活物質と、
    　水と、
    を含有する組成物。     A composition for a secondary battery electrode,
    A binder for a secondary battery electrode according to claim 1 or 2,
    Active material,
    water and,
    A composition containing:
  4. 　二次電池電極であって、
    　請求項１又は２に記載の二次電池電極用バインダーと、
    　活物質と、
    を含有する電極。     A secondary battery electrode,
    A binder for a secondary battery electrode according to claim 1 or 2,
    Active material,
    An electrode containing.
  5. 　さらに、前記活物質は、ケイ素含有物質である、請求項４に記載の電極。 Furthermore, the electrode according to claim 4, wherein the active material is a silicon-containing material.
  6. 　二次電池電極用バインダーの製造方法であって、
    　エチレン性不飽和カルボン酸単量体と、１分子中に（メタ）アクリロイル基を２個以上有し、かつ水酸基を有する架橋性単量体と、を含有する単量体組成物を重合する工程、
    を有する、製造方法。
          A method for producing a binder for a secondary battery electrode, comprising:
    Step of polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer and a crosslinkable monomer having two or more (meth) acryloyl groups in one molecule and having a hydroxyl group ,
    And a manufacturing method.
PCT/JP2019/042064 2018-10-31 2019-10-25 Binder for secondary battery electrodes, and use thereof WO2020090695A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004311306A (en) * 2003-04-09 2004-11-04 Sony Corp Battery
JP2018076446A (en) * 2016-11-10 2018-05-17 新日鉄住金化学株式会社 Soluble polyfunctional vinyl copolymer method for producing the same, curable resin composition containing the same, and coated film and cured product of the same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004311306A (en) * 2003-04-09 2004-11-04 Sony Corp Battery
JP2018076446A (en) * 2016-11-10 2018-05-17 新日鉄住金化学株式会社 Soluble polyfunctional vinyl copolymer method for producing the same, curable resin composition containing the same, and coated film and cured product of the same

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