WO2019230714A1 - Binder for secondary battery electrode and use thereof - Google Patents

Binder for secondary battery electrode and use thereof Download PDF

Info

Publication number
WO2019230714A1
WO2019230714A1 PCT/JP2019/021079 JP2019021079W WO2019230714A1 WO 2019230714 A1 WO2019230714 A1 WO 2019230714A1 JP 2019021079 W JP2019021079 W JP 2019021079W WO 2019230714 A1 WO2019230714 A1 WO 2019230714A1
Authority
WO
WIPO (PCT)
Prior art keywords
mass
monomer
binder
secondary battery
group
Prior art date
Application number
PCT/JP2019/021079
Other languages
French (fr)
Japanese (ja)
Inventor
篤史 西脇
直彦 斎藤
松崎　英男
Original Assignee
東亞合成株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 東亞合成株式会社 filed Critical 東亞合成株式会社
Priority to JP2020522208A priority Critical patent/JP7226442B2/en
Publication of WO2019230714A1 publication Critical patent/WO2019230714A1/en

Links

Classifications

    • 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
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/44—Preparation of metal salts or ammonium salts
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/62—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 use thereof.
  • This application is a related application of Japanese Patent Application No. 2018-102905, which is a Japanese patent application filed on May 30, 2018, and claims priority based on this Japanese application. It is incorporated herein by reference.
  • the electrodes used in these secondary batteries are produced by applying and drying a composition for forming an electrode mixture layer containing an active material and a binder on a current collector.
  • a composition for forming an electrode mixture layer containing an active material and a binder on a current collector 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.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • a binder excellent in dispersibility and binding property a binder containing an acrylic acid polymer aqueous solution or an aqueous dispersion is known.
  • NMP N-methyl-2-pyrrolidone
  • PVDF polyvinylidene fluoride
  • Patent Document 1 As a binder having good binding properties and an effect of improving durability, a binder using the acrylic acid polymer has been proposed.
  • Patent Document 1 by using a polymer obtained by cross-linking 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 describes a lithium battery binder comprising a monomer unit derived from acrylic acid as a constituent component and made of a polymer crosslinked with a specific crosslinking agent, and has a high capacity even when charging and discharging are repeated. It is described that the maintenance rate is shown.
  • Patent Document 3 discloses a binder for a lithium ion secondary battery positive electrode obtained by polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid compound and a copolymerizable compound having a specific solubility in water. A composition is disclosed, which describes that battery life characteristics can be improved.
  • any of the binders disclosed in Patent Documents 1 to 3 can impart good binding properties, but as the performance of the secondary battery improves, an electrode mixture layer with higher binding properties is required. It is like that.
  • the present disclosure has been made in view of such circumstances, and when a polymer having a carboxyl group such as an acrylic acid polymer is used as a binder, a secondary battery electrode having a higher binding property than conventional ones.
  • a composition for a secondary battery electrode mixture layer from which a mixture layer can be obtained is provided. Moreover, this indication provides the secondary battery electrode obtained using the said composition.
  • the present inventors have obtained a crosslink obtained by polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer and a specific crosslinkable monomer.
  • the present inventors have found that when a binder containing a polymer which is a polymer and has excellent dispersion stability is used, the binding property of the obtained electrode mixture layer can be made higher. According to the present disclosure, the following means are provided based on such findings.
  • a binder for a secondary battery electrode containing a crosslinked polymer is obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer,
  • the non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer
  • the crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group
  • the crosslinked polymer is neutralized to a neutralization degree of 80 to 100 mol%, and then has a particle diameter measured in an aqueous medium of 0.1 ⁇ m or more and 10 ⁇ m or less in terms of volume-based median diameter.
  • Binder [2] The amount of the crosslinkable monomer used is 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the non-crosslinkable monomer. Binder for water electrolyte secondary battery electrodes. [3] The crosslinkable monomer has one or more polymerizable unsaturated groups selected from the group consisting of a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acrylamide group, and a styryl group. The binder for secondary battery electrodes as described in [1] or [2].
  • the binder for a secondary battery electrode according to any one of [1] to [3], wherein the crosslinked polymer is a salt in which 50 mol% or more of the carboxyl groups of the crosslinked polymer are neutralized.
  • a method for producing a crosslinked polymer or a salt thereof used for a binder for a secondary battery electrode A polymerization step of polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer by precipitation polymerization;
  • the non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer,
  • the crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group, A method in which the crosslinked polymer is neutralized to a degree of neutralization of 80 to 100 mol%, and the particle diameter measured in an aqueous
  • a composition for a secondary battery electrode mixture layer comprising the binder according to any one of [1] to [4], an active material, and water.
  • a secondary battery electrode comprising a mixture layer formed on the current collector surface from the composition for a secondary battery electrode mixture layer according to [6] or [7].
  • the secondary battery electrode binder of the present disclosure exhibits excellent binding properties to electrode active materials and the like. Moreover, the said binder can exhibit favorable adhesiveness with a collector. For this reason, the electrode mixture layer containing the binder and the electrode provided with the binder have excellent binding properties and can maintain the integrity thereof.
  • the secondary battery electrode binder of the present disclosure contains a crosslinked polymer, and can be made into a composition for an electrode mixture layer by mixing with an active material and water.
  • the composition described above may be in a slurry state that can be applied to the current collector, or may be prepared in a wet powder state so that it can be applied to pressing on the surface of the current collector.
  • the secondary battery electrode of the present disclosure is obtained by forming a mixture layer formed from the above composition on the surface of a current collector such as a copper foil or an aluminum foil.
  • (meth) acryl means acryl and / or methacryl
  • (meth) acrylate means acrylate and / or methacrylate
  • the “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.
  • the binder of the present disclosure includes a crosslinked polymer.
  • the crosslinked polymer contains an ethylenically unsaturated carboxylic acid monomer in a constituent monomer unit, and is a crosslinked polymer having a carboxyl group.
  • the crosslinked polymer of the present disclosure (hereinafter also referred to as “the present polymer”) can be obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer.
  • the non-crosslinkable monomer is a compound having only one ethylenically unsaturated functional group in the molecule, and examples thereof include an ethylenically unsaturated carboxylic acid monomer and other ethylenically unsaturated monomers.
  • ⁇ Ethylenically unsaturated carboxylic acid monomer> By polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer (hereinafter also referred to as “component (a)”), a carboxyl group is introduced into the polymer. As a result, adhesion to the current collector is improved, and since the lithium ion desolvation effect and ion conductivity are excellent, an electrode having low resistance and excellent high rate characteristics can be obtained. Moreover, since water swelling property is provided, dispersion stability of the active material etc. in a mixture layer composition can be improved.
  • component (a) ethylenically unsaturated carboxylic acid monomer
  • Examples of ethylenically unsaturated carboxylic acid monomers include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamide alkyl such as (meth) acrylamide hexanoic acid and (meth) acrylamide dodecanoic acid Carboxylic acid; ethylenically unsaturated monomer having a carboxyl group such as succinic acid monohydroxyethyl (meth) acrylate, ⁇ -carboxy-caprolactone mono (meth) acrylate, ⁇ -carboxyethyl (meth) acrylate or the like (partial thereof) ) Alkali neutralized products are exemplified, and one of these may be used alone, or two or more may be used in combination.
  • a compound having an acryloyl group as a polymerizable functional group is preferable in that a polymer having a long primary chain length is obtained due to a high polymerization rate, and a binder has a good binding force, and particularly preferably acrylic acid. is there.
  • acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer having a high carboxyl group content can be obtained.
  • the content of the component (a) in the present polymer is not particularly limited, but can be, for example, 10% by mass to 100% by mass with respect to the total amount of non-crosslinkable monomers.
  • 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 is 50% by mass or more, it is preferable because the dispersion stability of the composition for electrode mixture layer becomes good and higher binding force is obtained, and may be 60% by mass or more, and 70% by mass or more. It may be 80% by mass or more.
  • the upper limit is, for example, 99.9% by mass or less, for example, 99.5% by mass or less, for example, 99% by mass or less, for example, 98% by mass or less, and for example, 95% by mass. Or less, for example 90% by mass or less, and for example 80% by mass or less.
  • it can be set as the range which combined these lower limits and upper limits suitably, but is 10 mass% or more and 100 mass% or less, for example, is 50 mass% or more and 100 mass% or less, for example, 50 mass% or more and 99.9 mass% or less, for example, 50 mass% or more and 98 mass% or less, for example, 70 mass% or more, 95 mass% or less, etc. can be used.
  • the non-crosslinkable monomer constituting the present polymer includes other ethylenically unsaturated monomers copolymerizable with these (hereinafter also referred to as “component (b)”).
  • component (b) examples include an ethylenically unsaturated monomer compound having an anionic group other than a carboxyl group such as a sulfonic acid group and a phosphoric acid group, or a nonionic ethylenically unsaturated monomer. Can be mentioned.
  • An anionic group other than a carboxyl group such as a sulfonic acid group and a phosphoric acid group, or a nonionic structural unit can be introduced into the polymer by polymerizing a monomer composition containing the component (b). It can.
  • a nonionic ethylenically unsaturated monomer is preferable from the viewpoint of obtaining an electrode having good bending resistance, and (meth) acrylamide is excellent in binder binding properties. And derivatives thereof, and nitrile group-containing ethylenically unsaturated monomers are preferred.
  • 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), it can exert a strong interaction with the electrode material, Good binding property to the active material can be exhibited. This is preferable because an electrode mixture layer that is firm and has good integrity can be obtained.
  • an alicyclic structure-containing ethylenically unsaturated monomer is preferred.
  • the ratio of a component can be 0 mass% or more and 90 mass% or less with respect to the total amount of a non-crosslinkable monomer.
  • the proportion of the component (b) may be 1% by mass or more and 60% by mass or less, 2% by mass or more and 50% by mass or less, or 5% by mass or more and 40% by mass or less. 10 mass% or more and 30 mass% or less may be sufficient.
  • the affinity to the electrolytic solution is improved, so that an effect of improving lithium ion conductivity can be expected.
  • Examples of (meth) acrylamide derivatives include N-alkyl (meth) acrylamide compounds such as isopropyl (meth) acrylamide and t-butyl (meth) acrylamide; Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl N-alkoxyalkyl (meth) acrylamide compounds such as (meth) acrylamide; and N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide are listed. You may use individually and may be used in combination of 2 or more type.
  • nitrile group-containing ethylenically unsaturated monomer examples include (meth) acrylonitrile; (meth) acrylic acid cyanoalkyl ester compounds such as (meth) acrylic acid cyanomethyl and (meth) acrylic acid cyanoethyl; 4-cyanostyrene Cyano group-containing unsaturated aromatic compounds such as 4-cyano- ⁇ -methylstyrene; vinylidene cyanide and the like, and one of these may be used alone, or two or more may be used in combination. May be used.
  • acrylonitrile is preferred because of its high nitrile group content.
  • Examples of the alicyclic structure-containing ethylenically unsaturated monomer include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth ) (Meth) acrylic acid cycloalkyl ester optionally having an aliphatic substituent such as cyclodecyl acrylate and cyclododecyl (meth) acrylate; isobornyl (meth) acrylate, adamantyl (meth) acrylate, (meth ) Dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and cyclohexanedimethanol mono (meth) acrylate and cyclodecane dimethanol mono (me
  • (meth) acrylic acid esters may be used as other nonionic ethylenically unsaturated monomers.
  • (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.
  • (Meth) acrylic acid alkyl ester compounds Aromatic (meth) acrylate compounds such as phenyl (meth) acrylate, phenylmethyl (meth) acrylate, phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate; (Meth) acrylic acid alkoxyalkyl ester compounds such as (meth) acrylic acid 2-methoxyethyl and (meth) acrylic acid ethoxyethyl; (Meth) acrylic acid hydroxyalkyl, (meth) acrylic acid hydroxypropyl and (meth) acrylic acid hydroxyalkyl ester compounds such as hydroxybutyl, etc. are used, and one of these is used alone. You may use it in combination of 2 or more types.
  • An aromatic (meth) acrylic acid ester compound can be preferably used from the viewpoints of adhesion with the active material and cycle characteristics.
  • compounds having an ether bond such as (meth) acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate are preferred. More preferred is 2-methoxyethyl (meth) acrylate.
  • nonionic ethylenically unsaturated monomers a compound having an acryloyl group is preferable in that a polymer having a long primary chain length is obtained due to a high polymerization rate, and a binder has a good binding force.
  • a compound having a glass transition temperature (Tg) of a homopolymer of 0 ° C. or less is preferable in that the obtained electrode has good bending resistance.
  • the present polymer may be in the form of a salt in which some or all of the carboxyl groups contained in the polymer are neutralized.
  • a salt in which some or all of the carboxyl groups contained in the polymer are neutralized.
  • 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 Examples include amine salts.
  • alkali metal salts and magnesium salts are preferred, and alkali metal salts are more preferred because they are less likely to adversely affect battery characteristics.
  • the crosslinkable monomer in the present disclosure includes a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups, and a monomer having a self-crosslinkable functional group such as a hydrolyzable silyl group. And a monomer having at least one polymerizable unsaturated group other than an allyl group.
  • the polyfunctional polymerizable monomer is a compound having two or more radically polymerizable unsaturated groups in the molecule and at least one polymerizable unsaturated group other than an allyl group.
  • Examples of the polymerizable unsaturated group other than the allyl group include groups represented by the following general formula (1) and general formula (2).
  • R 1 represents a hydrogen atom, a methyl group, a nitrile group or a halogen atom.
  • A represents an oxygen atom, a divalent organic group or a single bond.
  • CH 2 C (R 2 ) -B- (2)
  • R 2 represents a hydrogen atom, a methyl group, a nitrile group or a halogen atom.
  • B represents an arylene group which may have a substituent.
  • R 1 in the general formula (1) is a hydrogen atom or a methyl group
  • the general formula (1) represents a (meth) acryloyl group
  • A is an oxygen atom (meta ) Represents an acryloyloxy group.
  • a as the divalent organic group include NH, NR (R represents an alkyl group), and an alkylene group.
  • R 1 in the general formula (1) is a hydrogen atom or a methyl group and A is NH is referred to as a “(meth) acrylamide group”.
  • Other specific groups of the general formula (1) include ⁇ -cyanoacryloyl group, ⁇ -halogen acryloyl group and the like.
  • polyfunctional polymerizable monomer having the group represented by the general formula (1) examples include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and 1,6-hexanediol.
  • Di (meth) acrylates of polyhydric alcohols such as di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate; trimethylolpropane tri (Meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, Tri (meth) acrylates of trihydric or higher polyhydric alcohols such as pentaerythritol penta and
  • Specific examples of the general formula (2) include a styryl group.
  • Specific examples of the polyfunctional polymerizable monomer having these groups include divinylbenzene and divinylnaphthalene.
  • the monomer having a crosslinkable functional group capable of self-crosslinking include hydrolyzable silyl group-containing vinyl monomers, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate, and the like. Is mentioned. These compounds can 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 monomer having a polymerizable unsaturated group other than an allyl group and a hydrolyzable silyl group.
  • vinyl silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane
  • silyl such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, and methyldimethoxysilylpropyl acrylate Group-containing acrylic acid esters
  • silyl group-containing methacrylates such as trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate
  • trimethoxysilylpropyl vinyl ether etc
  • the amount of the crosslinkable monomer used is not particularly limited, but is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the total amount of non-crosslinkable monomers, More preferably, it is 0.5 mass part or more.
  • the amount of the crosslinkable monomer used may be, for example, 1.0 part by mass or more, may be 2.0 parts by mass or more, and may be, for example, 3.0 parts by mass or more.
  • the upper limit of the amount used is not particularly limited, but may be, for example, 20 parts by mass or less, may be, for example, 15 parts by mass or less, and may be, for example, 10 parts by mass or less. . Further, for example, it may be 5 parts by mass or less.
  • the crosslinkable monomer may be 3 parts by mass or less.
  • these upper limit and lower limit can be combined, for example, 0.1 to 20 parts by mass, for example, 0.1 to 10 parts by mass, Moreover, it is 0.5 mass part or more and 10 mass parts or less, for example.
  • the use amount of the crosslinkable monomer is 0.1 parts by mass or more, the binding property and the stability of the mixture layer slurry are preferable. If it is 20 parts by mass or less, the stability of the polymer tends to increase.
  • the amount of the crosslinkable monomer used is preferably 0.02 to 2.5 mol%, and preferably 0.03 to 1.5 mol% with respect to the total amount of the non-crosslinkable monomer. More preferably.
  • This polymer can lower the crosslinking density on the particle surface as compared with a crosslinked polymer crosslinked only by a crosslinking monomer having no polymerizable unsaturated group other than an allyl group.
  • the degree of swelling of the surface portion of the polymer in water is relatively high, and a bonding area with the active material and the current collector is ensured. Therefore, the binder containing the polymer exhibits good binding properties. It is conceivable that.
  • the above mechanism is an estimation and does not limit the scope of the present disclosure.
  • the polymer is well dispersed as water-swelling particles having an appropriate particle size without the polymer being present as a large particle size lump (secondary aggregate).
  • the binder containing the said crosslinked polymer can exhibit favorable binding performance, it is preferable.
  • the crosslinked polymer or a salt thereof has a particle size (water-swelled particle size) when dispersed in water having a neutralization degree of 80 to 100 mol% based on the carboxyl group of the crosslinked polymer.
  • the reference median diameter is preferably in the range of 0.1 ⁇ m or more and 10.0 ⁇ m or less.
  • a more preferable range of the particle diameter is 0.1 ⁇ m or more and 8.0 ⁇ m or less, a further preferable range is 0.1 ⁇ m or more and 7.0 ⁇ m or less, and a more preferable range is 0.2 ⁇ m or more and 5.0 ⁇ m or less. There is an even more preferable range of 0.5 ⁇ m or more and 3.0 ⁇ m or less.
  • a preferable range is 0.1 micrometer or more and 2.0 micrometers or less. If the particle size is in the range of 0.1 ⁇ m or more and 10.0 ⁇ m or less, the mixture layer composition is uniformly present in a suitable size, so that the mixture layer composition has high stability and excellent binding. It becomes possible to demonstrate wearability. If the particle diameter exceeds 10.0 ⁇ m or less, the binding property may be insufficient as described above. Moreover, there exists a possibility that coating property may become inadequate at the point which cannot obtain a smooth coating surface. On the other hand, when the particle diameter is less than 0.1 ⁇ m, there is a concern from the viewpoint of stable productivity. In addition, the said water swelling particle diameter can be measured by the method as described in an Example of this specification.
  • the particle diameter is measured when neutralized with an alkali metal hydroxide to a neutralization degree of 80 to 100 mol% and dispersed in water. do it.
  • a crosslinked polymer or a salt thereof often exists as aggregated particles in which primary particles are associated and aggregated in a powder or solution (dispersion) state.
  • the crosslinked polymer or salt thereof has extremely excellent dispersibility, and is neutralized to a neutralization degree of 80 to 100 mol% to give water.
  • the aggregated particles are released, and even if it is a primary particle dispersion or secondary aggregate, a stable dispersion state is formed in which the particle diameter is in the range of 0.1 to 10.0 ⁇ m. Is.
  • the particle size distribution which is a value obtained by dividing the volume-based median diameter of the water-swelling particle diameter by the number-based median diameter, is preferably 10 or less, more preferably 5.0 or less, from the viewpoints of binding properties and coatability. Yes, more preferably 3.0 or less, still more preferably 2.0 or less, and even more preferably 1.5 or less.
  • the lower limit of the particle size distribution is usually 1.0.
  • the particle diameter (dry particle diameter) of the crosslinked polymer or salt thereof when dried is preferably in the range of 0.03 ⁇ m or more and 3 ⁇ m or less in terms of volume-based median diameter.
  • a more preferable range of the particle diameter is 0.1 ⁇ m or more and 1 ⁇ m or less, and a further preferable range is 0.3 ⁇ m or more and 0.8 ⁇ m or less.
  • the present polymer or a salt thereof is neutralized with an acid group such as a carboxyl group derived from an ethylenically unsaturated carboxylic acid monomer so that the degree of neutralization is 20 mol% or more. It is preferably used as a salt embodiment.
  • the degree of neutralization is more preferably 50 mol%, still more preferably 60 mol% or more, still more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 85 mol%. More than mol%.
  • the upper limit of the degree of neutralization is 100 mol%, which may be 98 mol% or 95 mol%.
  • the range of the degree of neutralization can be appropriately combined with the above lower limit value and upper limit value, for example, may be 50 mol% or more and 100 mol% or less, or 70 mol% or more and 100 mol% or less. 80 mol% or more and 100 mol% or less.
  • the degree of neutralization is 20 mol% or more, water swellability is good and a dispersion stabilizing effect is easily obtained.
  • the said neutralization degree can be computed by calculation from the preparation value of the monomer which has acid groups, such as a carboxyl group, and the neutralizing agent used for neutralization.
  • the degree of neutralization is measured by IR measurement of the crosslinked polymer or salt thereof, and the powder after drying treatment 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 ⁇ of the carboxylate. This can be confirmed from the intensity ratio of the peak derived from the O group.
  • ⁇ Method for producing the present polymer or a salt thereof> known polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, emulsion polymerization and the like can be used, but precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) are considered in terms of productivity. ) Is preferred.
  • a heterogeneous polymerization method such as precipitation polymerization, suspension polymerization, and emulsion polymerization is preferable in that better performance can be obtained with respect to binding properties and the like, and precipitation polymerization is more preferable.
  • Precipitation polymerization is a method for producing a polymer by carrying out a polymerization reaction in a solvent that dissolves an unsaturated monomer as a raw material but does not substantially dissolve the produced polymer.
  • the polymer particles become larger due to aggregation and growth, and a dispersion of polymer particles in which primary particles of several tens to several hundreds of nm are secondarily aggregated to several ⁇ m to several tens of ⁇ m is obtained.
  • a dispersion stabilizer can also be used to control the particle size of the polymer.
  • the secondary aggregation can be suppressed by selecting a dispersion stabilizer, a polymerization solvent, and the like. In general, precipitation polymerization in which secondary aggregation is suppressed is also called dispersion polymerization.
  • a solvent selected from water and various organic solvents can be used as the polymerization solvent in consideration of the type of monomer used.
  • a solvent having a small chain transfer constant 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. Or you may use 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 preferred from the standpoints that a polymer having a small chain transfer constant and a high degree of polymerization (primary chain length) can be obtained, and that the operation can be easily performed during the process neutralization described later. .
  • a highly polar solvent preferably includes water and methanol.
  • the amount of the highly polar solvent used is preferably 0.05 to 20.0% by mass based on the total mass of the medium, more preferably 0.1 to 10.0% by mass, and even more preferably 0.1 to 5%. 0.0 mass%, more preferably 0.1 to 1.0 mass%. If the ratio of the highly polar solvent is 0.05% by mass or more, the effect on the neutralization reaction is recognized, and if it is 20.0% by mass or less, no adverse effect on the polymerization reaction is observed.
  • the production of the present polymer or a salt thereof preferably includes a polymerization step of polymerizing a monomer component containing a non-crosslinkable monomer and a crosslinkable monomer.
  • a non-crosslinkable monomer it is preferable that 50 to 100 mass% of ethylenically unsaturated carboxylic acid monomers are included with respect to the total amount of the non-crosslinkable monomer.
  • the ethylenically unsaturated carboxylic acid monomer the compounds listed as the component (a) in the description of the constituent monomer of the crosslinked polymer in the present specification can be used.
  • the non-crosslinkable monomer may contain 0% by mass or more and 50% by mass or less of other ethylenically unsaturated monomers in addition to the ethylenically unsaturated carboxylic acid monomer.
  • the compounds mentioned as the component (b) in the description of the constituent monomers of the crosslinked polymer in this specification can be used.
  • structural units derived from the component (a) and the component (b) are introduced at a ratio corresponding to the amount of use.
  • the crosslinkable monomer a monomer having at least one polymerizable unsaturated group other than an allyl group, which is exemplified as the crosslinkable monomer in the present polymer, can be used.
  • the monomer concentration at the time of polymerization is preferably higher from the viewpoint of obtaining a polymer having a longer primary chain length.
  • the monomer concentration at the start of polymerization is generally in the range of about 2 to 40% by mass, preferably in the range of 5 to 40% by mass.
  • the “monomer concentration” refers to the monomer concentration in the reaction solution at the time of starting the polymerization.
  • the present polymer may be produced by performing a polymerization reaction in the presence of a base compound. By carrying out the polymerization reaction in the presence of the base compound, the polymerization reaction can be carried out stably even under high monomer concentration conditions.
  • the monomer concentration may be 13.0% by mass or more, preferably 15.0% by mass or more, more preferably 17.0% by mass or more, and further preferably 19.0% by mass or more. And more preferably 20.0% by mass or more.
  • the monomer concentration is still preferably 22.0% by mass or more, and more preferably 25.0% by mass or more. Generally, the higher the monomer concentration during polymerization, the higher the molecular weight, and when this polymer is a crosslinked polymer, a polymer having a long primary chain length can be produced.
  • the upper limit of the monomer concentration varies depending on the type of monomer and solvent used, the polymerization method and various polymerization conditions, etc., but if the heat of polymerization reaction can be removed, precipitation polymerization is as described above. About 40%, about 50% for suspension polymerization, and about 70% for emulsion polymerization.
  • the basic compound is a so-called alkaline compound, and any of an inorganic basic compound and an organic basic compound may be used.
  • the polymerization reaction can be carried out stably even under high monomer concentration conditions, for example, exceeding 13.0% by mass.
  • a polymer obtained by polymerization at such a high monomer concentration has a high molecular weight (because of a long primary chain length) and is excellent in binding properties.
  • the inorganic base compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide.
  • 1 type (s) or 2 or more types can be used.
  • the organic base compound include ammonia and organic amine compounds such as monoethylamine, diethylamine and triethylamine, and tri-n-octylamine, and one or more of them can be used.
  • an organic amine compound is preferable from the viewpoints of polymerization stability and binding properties of a binder containing the obtained polymer or a salt thereof.
  • the amount of the base compound used is preferably in the range of 0.001 mol% to 4.0 mol% with respect to the ethylenically unsaturated carboxylic acid monomer. If the usage-amount of a basic compound is this range, a polymerization reaction can be performed smoothly.
  • the amount used may be 0.05 mol% or more and 4.0 mol% or less, 0.1 mol% or more and 4.0 mol% or less, or 0.1 mol% or more and 3.0 mol% or less. % Or less, or 0.1 mol% or more and 2.0 mol% or less.
  • the usage-amount of a base compound 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 base compound used is not taken into consideration.
  • the polymerization initiator may be a known polymerization initiator such as an azo compound, an organic peroxide, or an inorganic peroxide, but is 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, or the like so as to obtain an appropriate radical generation amount.
  • thermal initiation redox initiation using a reducing agent in combination
  • UV initiation or the like so as to obtain an appropriate radical generation amount.
  • Examples of the azo compound 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 these are used be able to.
  • organic peroxide examples include 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (manufactured by NOF Corporation, trade name “Pertetra A”), 1,1-di (t- Hexylperoxy) cyclohexane (same as “Perhexa HC”), 1,1-di (t-butylperoxy) cyclohexane (same as “PerhexaC”), n-butyl-4,4-di (t-butylperoxy) Valerate ("Perhexa V"), 2,2-di (t-butylperoxy) butane ("Perhexa 22"), t-butyl hydroperoxide ("Perbutyl H”), cumene hydroperoxide (Japan) Made by Oil Co., Ltd., trade name “Park Mill H”), 1,1,3,3-tetramethylbutyl hydroperoxide (“Perocta H”), t-
  • inorganic peroxide examples include potassium persulfate, sodium persulfate, and ammonium persulfate.
  • potassium persulfate sodium persulfate
  • sodium persulfate sodium persulfate
  • ammonium persulfate sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, sulfurous acid gas (SO 2 ), ferrous sulfate and the like can be used as a reducing agent.
  • the preferred use amount of the polymerization initiator is, for example, 0.001 to 2 parts by mass, for example 0.005 to 1 part by mass when the total amount of the monomer components to be used is 100 parts by mass, For example, it is 0.01 to 0.1 parts by mass.
  • the amount of the polymerization initiator used is 0.001 part by mass or more, the polymerization reaction can be stably performed, and when it is 2 parts by mass or less, a polymer having a long primary chain length is easily obtained.
  • the polymerization temperature is preferably 0 to 100 ° C., more preferably 20 to 80 ° C., although 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 polymerization reaction.
  • the polymerization time is preferably 1 minute to 20 hours, and more preferably 1 hour to 10 hours.
  • the polymer dispersion obtained through the polymerization step can be obtained in a powder state by subjecting the polymer dispersion to a reduced pressure and / or heat treatment in the drying step and distilling off the solvent.
  • a solid-liquid separation step such as centrifugation and filtration, water
  • methanol or the same solvent as the polymerization solvent.
  • step neutralization an alkali compound is added to the polymer dispersion obtained in the polymerization step to neutralize the polymer (hereinafter also referred to as “step neutralization”), and then the solvent is removed in the drying step. Good.
  • step neutralization an alkali compound is added when preparing the electrode mixture layer slurry to neutralize the polymer (hereinafter, May also be referred to as “sum”.
  • sum the process neutralization is preferable because the secondary aggregate tends to be easily broken.
  • the composition for a secondary battery electrode mixture layer of the present invention includes a binder containing the present polymer or a salt thereof, an active material, and water.
  • the usage-amount of this polymer or its salt in the electrode mixture layer composition of this invention is 0.1 to 20 mass% with respect to the whole quantity of an active material, for example.
  • 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 properties may not be obtained.
  • the dispersion stability of the active material or the like becomes insufficient, and the uniformity of the formed mixture layer may be lowered.
  • the electrode mixture layer composition may have a high viscosity and the coating property to the current collector may be lowered. As a result, bumps and irregularities are generated in the obtained mixture layer, which may adversely affect the electrode characteristics.
  • the amount of the present polymer and its salt used is within the above range, a composition having excellent dispersion stability can be obtained, and a mixture layer with extremely high adhesion to the current collector can be obtained. As a result, the durability of the battery is improved. Furthermore, the present bridge polymer and its salt show sufficiently high binding properties even in a small amount (for example, 5% by mass or less) with respect to the active material, and have a carboxy anion, so that the interface resistance is small and the high rate property is excellent. An electrode is obtained.
  • a lithium salt of a transition metal oxide can be used as the positive electrode active material.
  • a layered rock salt type and a spinel type lithium-containing metal oxide 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 ⁇ Li (Ni 1-ab Co a Al b ) ⁇ and the like.
  • the spinel positive electrode active material include lithium manganate.
  • phosphates In addition to oxides, phosphates, silicates, sulfur and the like are used, and examples of the phosphate include olivine type lithium iron phosphate.
  • the positive electrode active material one of the above may be used alone, or two or more may be used in combination as a mixture or a composite.
  • the positive electrode active material containing a layered rock salt type lithium-containing metal oxide when dispersed in water, the dispersion exhibits alkalinity by exchanging lithium ions on the active material surface with hydrogen ions in water. For this reason, there exists a possibility that the aluminum foil (Al) etc. which are general collector materials for positive electrodes may be corroded. In such a case, it is preferable to neutralize the alkali content eluted from the active material by using the unneutralized or partially neutralized polymer as a binder. In addition, the amount of unneutralized or partially neutralized polymer used should be such that the amount of carboxyl groups that are not neutralized in the polymer is equal to or greater than the amount of alkali eluted from the active material. Is preferred.
  • any positive electrode active material has low electrical conductivity, it is common to add a conductive auxiliary agent.
  • the conductive assistant include carbon-based materials such as carbon black, carbon nanotube, carbon fiber, graphite fine powder, and carbon fiber. Among these, carbon black, carbon nanotube, and carbon fiber are easy to obtain excellent conductivity. Are preferred. Moreover, as carbon black, ketjen black and acetylene black are preferable.
  • the conductive assistant one of the above may be used alone, or two or more may be used in combination. From the viewpoint of achieving both conductivity and energy density, the use amount of the conductive auxiliary agent can be, for example, 0.2 to 20% by mass with respect to the total amount of the active material, and for example, 0.2 to 10%. It can be made into the mass%.
  • the positive electrode active material may be a surface coated with a conductive carbon-based material.
  • examples of the negative electrode active material include carbon materials, lithium metals, lithium alloys, metal oxides, and the like, and one or more of them can 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, graphite such as natural graphite and artificial graphite, and Hard carbon is more preferable.
  • carbon-based active material such as natural graphite, artificial graphite, hard carbon, and soft carbon
  • graphite such as natural graphite and artificial graphite
  • Hard carbon is more preferable.
  • spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferred particle size range is, for example, 1 to 20 ⁇ m, and for example, 5 to 15 ⁇ m.
  • a metal or metal oxide that can occlude lithium such as silicon or tin can be used as the negative electrode active material.
  • silicon has a higher capacity than graphite, and an active material composed of silicon-based materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter referred to as “silicon-based active material”).
  • silicon-based active material has a high capacity, but has a large volume change due to charge / discharge. For this reason, it is preferable to use together with the carbon-based active material. In this case, if the compounding amount of the silicon-based active material is large, the electrode material may be collapsed and the cycle characteristics (durability) may be greatly reduced. From such a point of view, when a silicon-based active material is used in combination, the amount used is, for example, 60% by mass or less, for example, 30% by mass or less with respect to the carbon-based active material.
  • the binder containing the present polymer has a structural unit (component (a)) derived from the ethylenically unsaturated carboxylic acid monomer.
  • component (a) has a high affinity for the silicon-based active material and exhibits good binding properties.
  • the binder of the present disclosure exhibits an excellent binding property even when a high-capacity type active material containing a silicon-based active material is used, and thus is effective for improving the durability of the obtained electrode. It is considered a thing.
  • the carbon-based active material itself has good electrical conductivity, it is not always necessary to add a conductive additive.
  • a conductive additive is added for the purpose of further reducing the resistance, the amount used is, for example, 10% by mass or less, for example, 5% by weight or less with respect to the total amount of the active material from the viewpoint of energy density. It is.
  • the amount of the active material used is, for example, in the range of 10 to 75% by mass, for example, 30 to 65% by mass with respect to the total amount of the composition. Range.
  • the amount of the active material used is 10% by mass or more, the migration of the binder and the like is suppressed, and the medium drying cost is advantageous.
  • it is 75 mass% or less, the fluidity
  • the amount of the active material used is, for example, in the range of 60 to 97% by mass relative to the total amount of the composition, and for example, 70 to 90 It is the range of mass%. Further, from the viewpoint of energy density, it is preferable that the non-volatile components other than the active material such as the binder and the conductive assistant are as small as possible within a range in which necessary binding properties and conductivity are ensured.
  • the composition for the secondary battery electrode mixture layer uses water as a medium.
  • water-soluble organic solvents such as lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, tetrahydrofuran, N-methylpyrrolidone, etc. It is good also as a mixed solvent.
  • the ratio 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 determined from the viewpoints of slurry coating properties, energy costs required for drying, and productivity. From, for example, it can be in the range of 25-90% by mass, and can be, for example, 35-70% by mass.
  • the content of the medium can be set in the range of 3 to 40% by mass, for example, from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of ⁇ 30% by mass.
  • the binder of the present disclosure may be composed only of the present polymer or a salt thereof, but other binders such as styrene / butadiene latex (SBR), acrylic latex, and polyvinylidene fluoride latex are also available. You may use an ingredient together.
  • SBR styrene / butadiene latex
  • acrylic latex acrylic latex
  • polyvinylidene fluoride latex polyvinylidene fluoride latex
  • the amount used can be, for example, 0.1 to 5% by mass or less, for example, 0.1 to 2% by mass or less based on the active material. For example, it can be 0.1 to 1% by mass or less.
  • the amount of other binder components used exceeds 5% by mass, the resistance increases and the high rate characteristics may be insufficient.
  • styrene / butadiene latex is preferable in terms of excellent balance between binding properties and bending resistance.
  • the styrene / butadiene latex is a copolymer having a structural unit derived from an aromatic vinyl monomer such as styrene and a structural unit derived from an aliphatic conjugated diene monomer such as 1,3-butadiene.
  • An aqueous dispersion is shown.
  • the aromatic vinyl monomer include ⁇ -methylstyrene, vinyltoluene, divinylbenzene and the like in addition to styrene, and one or more of these can be used.
  • the structural unit derived from the aromatic vinyl monomer in the copolymer can be, for example, in the range of 20 to 60% by mass mainly from the viewpoint of binding properties, and for example, 30 to 50%. It can be made into the range of the mass%.
  • Examples of the aliphatic conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. Butadiene and the like can be mentioned, and one or more of these can be used.
  • the structural unit derived from the aliphatic conjugated diene monomer in the copolymer is, for example, 30 to 70% by mass in that the binder binding property and the flexibility of the resulting electrode are good. For example, it can be in the range of 40 to 60% by mass.
  • the styrene / butadiene latex is a monomer containing a nitrile group such as (meth) acrylonitrile, )
  • a carboxyl group-containing monomer such as acrylic acid, itaconic acid and maleic acid may be used as a copolymerization monomer.
  • the structural unit derived from the other monomer in the copolymer can be, for example, in the range of 0 to 30% by mass, and can be in the range of 0 to 20% by mass, for example.
  • the composition for a secondary battery electrode mixture layer of the present disclosure contains the above active material, water, and binder as essential components, and can be obtained by mixing each component using a known means.
  • the mixing method of each component is not particularly limited, and a known method can be adopted.
  • a method of mixing with a dispersion medium such as water and kneading the mixture is preferable.
  • the composition for an electrode mixture layer is obtained in a slurry state, it is preferable to finish the slurry without any poor dispersion or aggregation.
  • a mixing means known mixers such as a planetary mixer, a thin film swirl mixer, and a self-revolving mixer can be used, but a thin film swirl mixer is used because a good dispersion state can be obtained in a short time. It is preferable to carry out. Moreover, when using a thin film swirling mixer, it is preferable to perform preliminary dispersion with a stirrer such as a disper in advance.
  • the viscosity of the slurry can be, for example, in the range of 500 to 100,000 mPa ⁇ s as B-type viscosity at 60 rpm, and for example, in the range of 1,000 to 50,000 mPa ⁇ s. it can.
  • the electrode mixture layer composition when obtained in a wet powder state, it is preferably kneaded to a uniform state without unevenness in density using a Henschel mixer, blender, planetary mixer, biaxial kneader, or the like.
  • the electrode for a secondary battery of the present disclosure includes a mixture layer formed from the above composition for an electrode mixture layer on the surface of a current collector such as copper or aluminum.
  • the mixture layer is formed by drying and removing a medium such as water after applying the composition for an electrode mixture layer of the present disclosure to the surface of the current collector.
  • the method for applying the mixture layer composition is not particularly limited, and a known method such as a doctor blade method, a dip method, a roll coat method, a comma coat method, a curtain coat method, a gravure coat method, and an extrusion method is adopted. be able to.
  • the said drying can be performed by well-known methods, such as hot air spraying, pressure reduction, (far) infrared rays, and microwave irradiation.
  • the mixture layer obtained after drying is subjected to a compression treatment by a die press, a roll press or the like.
  • a compression treatment by a die press, a roll press or the like.
  • the strength of the mixture layer and the adhesiveness 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, and the thickness of the mixture layer after compression is generally about 4 to 200 ⁇ m.
  • a secondary battery can be produced by providing the electrode for a secondary battery of the present disclosure with a separator and an electrolytic solution.
  • the electrolytic solution may be liquid or gelled.
  • the separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of ensuring ionic conductivity by preventing a short circuit due to contact between both electrodes and holding an electrolytic solution.
  • the separator is preferably a film-like insulating microporous film having good ion permeability and mechanical strength.
  • polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, and the like can be used.
  • the electrolytic solution a known one that is generally used according to the type of the active material can be used.
  • specific solvents cyclic carbonates having high dielectric constant and high electrolyte dissolving ability such as propylene carbonate and ethylene carbonate, and low viscosity chains such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate are used. And the like, and these can be used alone or as a mixed solvent.
  • the electrolytic solution is used by dissolving lithium salts such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , and LiAlO 4 in these solvents.
  • an aqueous potassium hydroxide solution can be used as the electrolytic solution.
  • a secondary battery is obtained by making a positive electrode plate and a negative electrode plate partitioned by a separator into a spiral or laminated structure and storing them in a case or the like.
  • the secondary battery electrode binder disclosed in the present specification exhibits excellent binding properties with the electrode material and excellent adhesion with the current collector in the mixture layer. Secondary batteries equipped with electrodes obtained using the above binders are able to ensure good integrity and are expected to show good durability (cycle characteristics) even after repeated charge and discharge. Suitable for batteries and the like. Moreover, according to the indication of this specification, the manufacturing method of the binder for secondary battery electrodes, the manufacturing method of the electrode for secondary batteries, and the electrode for secondary batteries are also provided.
  • the reactor was sufficiently purged with nitrogen and then 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) (trade name “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) 0 as a polymerization initiator When .040 parts was added, white turbidity was observed in the reaction solution, and this point was taken as the polymerization initiation point. The monomer concentration was calculated to be 15.0%. 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. after 6 hours had elapsed from the polymerization start point.
  • the external temperature water bath temperature
  • the internal temperature was maintained at 65 ° C., and cooling of the reaction liquid was started when 12 hours had elapsed from the polymerization start point. After the internal temperature dropped to 25 ° C., lithium hydroxide monohydrate (hereinafter referred to as “LiOH”). 52.5 parts) of “H 2 O”. After the addition, stirring was continued at room temperature for 12 hours 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 the medium. Moreover, it was confirmed by liquid chromatography analysis that the obtained polymer had a composition as prepared.
  • LiOH lithium hydroxide monohydrate
  • the resulting polymerization reaction liquid was centrifuged to precipitate polymer particles, and then the supernatant was removed. Then, after the sediment was redispersed in acetonitrile having the same weight as the polymerization reaction solution, the washing operation of sedimenting the polymer particles by centrifugation and removing the supernatant was repeated twice.
  • the precipitate was collected, dried under reduced pressure at 80 ° C. for 3 hours, and volatile components were removed to obtain a carboxyl group-containing polymer salt R-1 powder. Since the crosslinked polymer salt R-1 has a hygroscopic property, it was hermetically stored in a container having a water vapor barrier property.
  • IR measurement was performed on the powder of the carboxyl group-containing polymer salt R-1, and the degree of neutralization was determined from the intensity ratio of the C ⁇ O group-derived peak of the carboxylic acid and the C ⁇ O-derived peak of the carboxylic acid Li. It was 90 mol% equal to the calculated value from the preparation.
  • a hydrogel swollen in water was prepared.
  • the particle size distribution of the hydrogel was measured with a laser diffraction / scattering particle size distribution meter (Microtrac MT-3300EXII, manufactured by Microtrac Bell) using ion-exchanged water as a dispersion medium.
  • a laser diffraction / scattering particle size distribution meter Microtrac MT-3300EXII, manufactured by Microtrac Bell
  • an amount of the hydrogel capable of obtaining an appropriate scattered light intensity was added, and the particle size distribution shape measured after a few minutes was stabilized.
  • volume-based particle size distribution measurement was performed and the median diameter (D50) was determined as the average particle diameter, which was 1.7 ⁇ m.
  • volume-based median diameter / number-based median diameter is less than 1.5
  • volume-based median diameter / number-based median diameter is 1.5 or more and less than 3.0
  • Volume-based median diameter / number-based median diameter is 3 0.0 or more and less than 10
  • AA Acrylic acid DMAA: Dimethylacrylamide
  • HEA Hydroxyethyl acrylate
  • TMPTMA Trimethylolpropane trimethacrylate (Kyoeisha Chemical Co., Ltd., trade name “Light Ester TMP”)
  • EDGMA Ethylene glycol dimethacrylate (Fuji Film Wako Pure Chemical Industries, reagent "ethylene dimethacrylate”)
  • HAPMA 2-hydroxy-3-acryloyloxypropyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester G-201P”)
  • DPEPA Dipentaerythritol penta and hexaacrylate (trade name “Aronix M-403” manufactured by Toagosei Co., Ltd.)
  • PETA Pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co.,
  • graphite which is an active material for a negative electrode, or silicon particles and graphite
  • the composition for a mixture layer using a crosslinked polymer salt as a binder its stability and the formed mixture layer / current collector
  • the peel strength between the bodies was measured.
  • Natural graphite manufactured by Nippon Graphite Co., Ltd., trade name “CGB-10” was used as graphite, and (Sigma-Aldrich, Si nanopowder, particle size ⁇ 100 nm) was used as silicon particles.
  • Example 1 After weighing 3.2 parts of powdered crosslinked polymer Li salt R-1 into 100 parts of natural graphite and mixing well in advance, 160 parts of ion exchange water was added and predispersed with a disper, and then a thin film swirl type This dispersion was carried out for 15 seconds under the condition of a peripheral speed of 20 m / sec using a mixer (manufactured by Primics, FM-56-30) to obtain a slurry-like composition for a negative electrode mixture layer. The slurry concentration (solid content) was calculated to be 39.2%.
  • the mixture layer composition is applied onto a 20 ⁇ m thick copper foil (manufactured by Nippon Foil Co., Ltd.) and dried in an air dryer at 100 ° C. for 15 minutes. A layer was formed. Thereafter, the mixture layer was rolled to have a thickness of 70 ⁇ 5 ⁇ m and a packing density of 1.70 ⁇ 0.20 g / cm 3 to prepare a negative electrode.
  • the mixture layer surface of the sample was attached to a double-sided tape fixed on a horizontal surface to prepare a sample for a peel test. After the test sample was dried at 60 ° C. under reduced pressure overnight, 90 ° peeling at a tensile speed of 50 mm / min was performed, and the peel strength between the mixture layer and the copper foil was measured. The peel strength was as good as 16.0 N / m.
  • Example 2 to 24 and Comparative Examples 1 and 2 A mixture layer composition was prepared by the same operation as in Example 1 except that the carboxyl group-containing polymer salt used as the active material and the binder was used as shown in Tables 3 to 5.
  • Example 3 and Example 4 natural graphite and silicon particles were stirred for 1 hour at 400 rpm using a planetary ball mill (manufactured by FRITSCH, P-5), and the resulting mixture was powdered cross-linked polymer.
  • a mixture layer composition was prepared by performing the same operation as in Example 1. The 90 ° peel strength of each mixture layer composition was evaluated, and the results are shown in Tables 3 to 5.
  • an electrode mixture layer composition containing a binder for a secondary battery electrode belonging to the present disclosure and an electrode produced using the electrode mixture layer composition had a high value, and exhibited excellent binding properties.
  • Comparative Example 1 using a polymer salt not using a crosslinkable monomer and Comparative Example 2 using a crosslinkable polymer salt using a crosslinkable monomer having no polymerizable unsaturated group other than an allyl group The peel strength was a low value compared to the examples.
  • the secondary battery electrode binder of the present disclosure exhibits excellent binding properties in the mixture layer, the secondary battery including the electrode obtained using the binder has good durability (cycle characteristics). ) And is expected to be applied to in-vehicle secondary batteries. It is also useful for the use of active materials containing silicon, and is expected to contribute to higher battery capacity.
  • the binder for a secondary battery electrode of the present disclosure can be suitably used particularly for a nonaqueous electrolyte secondary battery electrode, and is particularly useful for a nonaqueous electrolyte lithium ion secondary battery having a high energy density.

Abstract

Provided is a binder for a secondary battery electrode comprising a crosslinked polymer. The binder is for a composition for a secondary battery electrode mixture layer capable of imparting excellent binding properties. The crosslinked polymer is obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer. The non-crosslinkable monomer includes 50% by mass or more and 100% by mass or less of an ethylenically-unsaturated carboxylic acid monomer relative to the total amount of the non-crosslinkable monomer. The crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group, and the crosslinked polymer has a particle diameter measured in an aqueous medium after neutralization to a neutralization degree of 80-100 mol% is 0.1 μm or more and 10 μm or less in terms of volume-based median diameter.

Description

二次電池電極用バインダー及びその利用Secondary battery electrode binder 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５月３０日に出願された日本国特許出願である特願２０１８－１０２９０５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 use thereof.
(Cross-reference of related applications)
This application is a related application of Japanese Patent Application No. 2018-102905, which is a Japanese patent application filed on May 30, 2018, and claims priority based on this Japanese application. It is 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。また、分散性及び結着性に優れるバインダーとして、アクリル酸系重合体水溶液又は水分散液を含むバインダーが知られている。一方、正極合剤層に用いられるバインダーとしては、ポリフッ化ビニリデン（ＰＶＤＦ）のＮ－メチル－２－ピロリドン（ＮＭＰ）溶液が広く使用されている。 As the secondary battery, various power storage devices such as a nickel hydride secondary battery, a lithium ion secondary battery, and an electric double layer capacitor have been put into practical use. The electrodes used in these secondary batteries are produced by applying and drying a composition for forming an electrode mixture layer containing an active material and a binder on a current collector. 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. Further, as a binder excellent in dispersibility and binding property, a binder containing an acrylic acid polymer aqueous solution or an aqueous dispersion is known. On the other hand, as a binder used for the positive electrode mixture layer, an N-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride (PVDF) is widely used.
　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, in order to increase the electric capacity of a lithium ion secondary battery, specifications using a silicon-based active material as an active material for a negative electrode are increasing. However, silicon-based active materials are known to have a large volume change during charge and discharge, and peeling or dropping of the electrode mixture layer occurs as they are repeatedly used, resulting in a decrease in battery capacity and cycle characteristics. There was a problem that (durability) deteriorated. In order to suppress such inconveniences, it is generally effective to increase the binding property of the binder, and studies have been conducted on improving the binding property of the binder for the purpose of improving durability.
　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、アクリル酸由来のモノマー単位を構成成分に含み、特定の架橋剤により架橋したポリマーからなるリチウム電池用結着剤が記載され、充放電を繰り返した場合であっても高い容量維持率を示すことが記載されている。特許文献３には、エチレン性不飽和カルボン酸化合物と、水に対して特定の溶解度を有する共重合可能な化合物を含む単量体組成物を重合して得られるリチウムイオン二次電池正極用バインダー組成物が開示され、電池の寿命特性を優れたものとすることができることが記載されている。 As a binder having good binding properties and an effect of improving durability, a binder using the acrylic acid polymer has been proposed.
In Patent Document 1, by using a polymer obtained by cross-linking 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 describes a lithium battery binder comprising a monomer unit derived from acrylic acid as a constituent component and made of a polymer crosslinked with a specific crosslinking agent, and has a high capacity even when charging and discharging are repeated. It is described that the maintenance rate is shown. Patent Document 3 discloses a binder for a lithium ion secondary battery positive electrode obtained by polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid compound and a copolymerizable compound having a specific solubility in water. A composition is disclosed, which describes that battery life characteristics can be improved.
国際公開第２０１４／０６５４０７号International Publication No. 2014/065407 国際公開第２０１５／１６３３０２号International Publication No. 2015/163302 国際公開第２０１６／０６７６３５号International Publication No. 2016/067635
　特許文献１～３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。 Any of the binders disclosed in Patent Documents 1 to 3 can impart good binding properties, but as the performance of the secondary battery improves, an electrode mixture layer with higher binding properties is required. It is like that.
　本開示は、このような事情に鑑みてなされたものであり、アクリル酸系重合体等のカルボキシル基を有する重合体をバインダーとして用いた際に、従来よりも結着性の高い二次電池電極合剤層を得ることができる二次電池電極合剤層用組成物を提供する。また、本開示は、上記組成物を用いて得られる二次電池電極を提供する。 The present disclosure has been made in view of such circumstances, and when a polymer having a carboxyl group such as an acrylic acid polymer is used as a binder, a secondary battery electrode having a higher binding property than conventional ones. Provided is a composition for a secondary battery electrode mixture layer from which a mixture layer can be obtained. Moreover, this indication provides the secondary battery electrode obtained using the said composition.
　本発明者らは、上記課題を解決するために鋭意検討した結果、エチレン性不飽和カルボン酸単量体と特定の架橋性単量体を含む単量体組成物を重合して得られた架橋重合体であって、分散安定性に優れる重合体を含有するバインダーを用いた場合に、得られる電極合剤層の結着性をより高いものとすることができるという知見を得た。本開示によれば、こうした知見に基づき以下の手段が提供される。 As a result of diligent studies to solve the above problems, the present inventors have obtained a crosslink obtained by polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer and a specific crosslinkable monomer. The present inventors have found that when a binder containing a polymer which is a polymer and has excellent dispersion stability is used, the binding property of the obtained electrode mixture layer can be made higher. According to the present disclosure, the following means are provided based on such findings.
〔１〕架橋重合体を含有する二次電池電極用バインダーであって、
　前記架橋重合体は、非架橋性単量体及び架橋性単量体を含む単量体組成物を重合して得られ、
　前記非架橋性単量体は、該非架橋性単量体の総量に対し、エチレン性不飽和カルボン酸単量体を５０質量％以上１００質量％以下含み、
　前記架橋性単量体は、アリル基以外の重合性不飽和基を少なくとも１個有する単量体を含み、
　前記架橋重合体は、中和度８０～１００モル％に中和された後、水媒体中で測定した粒子径が、体積基準メジアン径で０．１μｍ以上、１０μｍ以下である、二次電池電極用バインダー。
〔２〕前記架橋性単量体の使用量は、前記非架橋性単量体の総量１００質量部に対し、０．１質量部以上、１０質量部以下である前記〔１〕に記載の非水電解質二次電池電極用バインダー。
〔３〕前記架橋性単量体は、（メタ）アクリロイル基、（メタ）アクリロイルオキシ基、（メタ）アクリルアミド基及びスチリル基からなる群より選ばれる１種以上の重合性不飽和基を有する前記〔１〕又は〔２〕に記載の二次電池電極用バインダー。
〔４〕前記架橋重合体は、該架橋重合体が有するカルボキシル基の５０モル％以上が中和された塩である前記〔１〕～〔３〕のいずれかに記載の二次電池電極用バインダー。
〔５〕二次電池電極用バインダーに用いられる架橋重合体又はその塩の製造方法であって、
　沈殿重合法により、非架橋性単量体及び架橋性単量体を含む単量体組成物を重合する重合工程を備え、
　前記非架橋性単量体は、該非架橋性単量体の総量に対し、エチレン性不飽和カルボン酸単量体を５０質量％以上１００質量％以下含み、
　前記架橋性単量体は、アリル基以外の重合性不飽和基を少なくとも１個有する単量体を含み、
　前記架橋重合体は、中和度８０～１００モル％に中和された後、水媒体中で測定した粒子径が、体積基準メジアン径で０．１μｍ以上、１０μｍ以下である、方法。
〔６〕前記〔１〕～〔４〕のいずれかに記載のバインダー、活物質及び水を含む二次電池電極合剤層用組成物。
〔７〕負極活物質として炭素系材料またはケイ素系材料を含む前記〔６〕に記載の二次電池電極合剤層用組成物。
〔８〕集電体表面に、前記〔６〕又は〔７〕に記載の二次電池電極合剤層用組成物から形成される合剤層を備えた二次電池電極。 [1] A binder for a secondary battery electrode containing a crosslinked polymer,
The crosslinked polymer is obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer,
The non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer,
The crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group,
The crosslinked polymer is neutralized to a neutralization degree of 80 to 100 mol%, and then has a particle diameter measured in an aqueous medium of 0.1 μm or more and 10 μm or less in terms of volume-based median diameter. Binder.
[2] The amount of the crosslinkable monomer used is 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the non-crosslinkable monomer. Binder for water electrolyte secondary battery electrodes.
[3] The crosslinkable monomer has one or more polymerizable unsaturated groups selected from the group consisting of a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acrylamide group, and a styryl group. The binder for secondary battery electrodes as described in [1] or [2].
[4] The binder for a secondary battery electrode according to any one of [1] to [3], wherein the crosslinked polymer is a salt in which 50 mol% or more of the carboxyl groups of the crosslinked polymer are neutralized. .
[5] A method for producing a crosslinked polymer or a salt thereof used for a binder for a secondary battery electrode,
A polymerization step of polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer by precipitation polymerization;
The non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer,
The crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group,
A method in which the crosslinked polymer is neutralized to a degree of neutralization of 80 to 100 mol%, and the particle diameter measured in an aqueous medium is 0.1 μm or more and 10 μm or less in terms of volume-based median diameter.
[6] A composition for a secondary battery electrode mixture layer comprising the binder according to any one of [1] to [4], an active material, and water.
[7] The composition for a secondary battery electrode mixture layer according to [6], wherein the negative electrode active material includes a carbon-based material or a silicon-based material.
[8] A secondary battery electrode comprising a mixture layer formed on the current collector surface from the composition for a secondary battery electrode mixture layer according to [6] or [7].
　本開示の二次電池電極用バインダーは、電極活物質等に対して優れた結着性を示す。また、上記バインダーは、集電体とも良好な接着性を発揮することができる。このため、上記バインダーを含む電極合剤層及びこれを備えた電極は、結着性に優れるとともにその一体性を維持することができる。 The secondary battery electrode binder of the present disclosure exhibits excellent binding properties to electrode active materials and the like. Moreover, the said binder can exhibit favorable adhesiveness with a collector. For this reason, the electrode mixture layer containing the binder and the electrode provided with the binder have excellent binding properties and can maintain the integrity thereof.
　以下、本開示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ならびに開示は、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, representative and non-limiting specific examples of the present disclosure will be described in detail with reference to the drawings as appropriate. This detailed description is intended merely to provide those skilled in the art with details to implement preferred examples of the present disclosure and is not intended to limit the scope of the present disclosure. In addition, the additional features and disclosures disclosed below can be used separately from or together with other features and disclosures to provide further improved secondary battery electrode binders and uses 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 combinations of features and steps disclosed in the following detailed description are not essential in carrying out the present disclosure in the broadest sense, and are particularly only for explaining representative specific examples of the present disclosure. It is described. Moreover, various features of the representative embodiments described above and below, as well as those described in the independent and dependent claims, are described herein in providing additional and useful embodiments of the present disclosure. They do not have to be combined in the specific examples given 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 features described in this specification and / or claims, apart from the configuration of the features described in the examples and / or claims, are individually disclosed as limitations on the original disclosure and claimed specific matters. And are intended to be disclosed independently of each other. Further, all numerical ranges and group or group descriptions are intended to disclose intermediate configurations thereof as a limitation to the original disclosure and claimed subject matter.
　本開示の二次電池電極用バインダーは、架橋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電極合剤層用組成物とすることができる。上記の組成物は、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上記組成物から形成される合剤層を形成することにより、本開示の二次電池電極が得られる。 The secondary battery electrode binder of the present disclosure contains a crosslinked polymer, and can be made into a composition for an electrode mixture layer by mixing with an active material and water. The composition described above may be in a slurry state that can be applied to the current collector, or may be prepared in a wet powder state so that it can be applied to pressing on the surface of the current collector. The secondary battery electrode of the present disclosure is obtained by forming a mixture layer formed from the above composition on the surface of a current collector such as a copper foil or an aluminum foil.
　以下に、本開示の二次電池電極用バインダー、当該バインダーを用いて得られる二次電池電極合剤層用組成物及び二次電池電極の各々について詳細に説明する。
　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。 Hereinafter, each of the binder for a secondary battery electrode of the present disclosure, the composition for a secondary battery electrode mixture layer obtained using the binder, and the secondary battery electrode will be described in detail.
In the present specification, “(meth) acryl” means acryl and / or methacryl, and “(meth) acrylate” means acrylate and / or methacrylate. The “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.
＜バインダー＞
　本開示のバインダーは、架橋重合体を含む。当該架橋重合体は、構成単量体単位にエチレン性不飽和カルボン酸単量体を含むものであり、カルボキシル基を有する架橋重合体である。 <Binder>
The binder of the present disclosure includes a crosslinked polymer. The crosslinked polymer contains an ethylenically unsaturated carboxylic acid monomer in a constituent monomer unit, and is a crosslinked polymer having a carboxyl group.
＜架橋重合体の構成単量体＞
　本開示の架橋重合体（以下、「本重合体」ともいう）は、非架橋性単量体及び架橋性単量体を含む単量体組成物を重合することにより得ることができる。非架橋性単量体は、分子内にエチレン性不飽和官能基を１個のみ有する化合物であり、エチレン性不飽和カルボン酸単量体及びその他のエチレン性不飽和単量体が挙げられる。 <Constituent monomer of crosslinked polymer>
The crosslinked polymer of the present disclosure (hereinafter also referred to as “the present polymer”) can be obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer. The non-crosslinkable monomer is a compound having only one ethylenically unsaturated functional group in the molecule, and examples thereof include an ethylenically unsaturated carboxylic acid monomer and other ethylenically unsaturated monomers.
＜エチレン性不飽和カルボン酸単量体＞
　エチレン性不飽和カルボン酸単量体（以下、「（ａ）成分」ともいう）を含む単量体組成物を重合することにより、本重合体へカルボキシル基が導入される。これにより、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、合剤層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。 <Ethylenically unsaturated carboxylic acid monomer>
By polymerizing a monomer composition containing an ethylenically unsaturated carboxylic acid monomer (hereinafter also referred to as “component (a)”), a carboxyl group is introduced into the polymer. As a result, adhesion to the current collector is improved, and since the lithium ion desolvation effect and ion conductivity are excellent, an electrode having low resistance and excellent high rate characteristics can be obtained. Moreover, since water swelling property is provided, dispersion stability of the active material etc. in a mixture layer composition can be improved.
　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ル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、カルボキシル基含有量の高い重合体を得ることができる。 Examples of ethylenically unsaturated carboxylic acid monomers include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamide alkyl such as (meth) acrylamide hexanoic acid and (meth) acrylamide dodecanoic acid Carboxylic acid; ethylenically unsaturated monomer having a carboxyl group such as succinic acid monohydroxyethyl (meth) acrylate, ω-carboxy-caprolactone mono (meth) acrylate, β-carboxyethyl (meth) acrylate or the like (partial thereof) ) Alkali neutralized products are exemplified, and one of these may be used alone, or two or more may be used in combination. Among them, a compound having an acryloyl group as a polymerizable functional group is preferable in that a polymer having a long primary chain length is obtained due to a high polymerization rate, and a binder has a good binding force, and particularly preferably acrylic acid. is there. When acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer having a high carboxyl group content can be obtained.
　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、非架橋性単量体の総量に対して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。下限が５０質量％以上の場合、電極合剤層用組成物の分散安定性が良好となり、より高い結着力が得られるため好ましく、６０質量％以上であってもよく、７０質量％以上であってもよく、８０質量％以上であってもよい。また、上限は、例えば、９９．９質量％以下であり、また例えば９９．５質量％以下であり、また例えば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％以下であり、また例えば８０質量％以下である。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、１０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５０質量％以上、９９．９質量％以下であり、また例えば５０質量％以上、９８質量％以下であり、また例えば７０質量％以上、９５質量％以下などとすることができる。 The content of the component (a) in the present polymer is not particularly limited, but can be, for example, 10% by mass to 100% by mass with respect to the total amount of non-crosslinkable monomers. By containing the component (a) within 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. When the lower limit is 50% by mass or more, it is preferable because the dispersion stability of the composition for electrode mixture layer becomes good and higher binding force is obtained, and may be 60% by mass or more, and 70% by mass or more. It may be 80% by mass or more. The upper limit is, for example, 99.9% by mass or less, for example, 99.5% by mass or less, for example, 99% by mass or less, for example, 98% by mass or less, and for example, 95% by mass. Or less, for example 90% by mass or less, and for example 80% by mass or less. As a range, it can be set as the range which combined these lower limits and upper limits suitably, but is 10 mass% or more and 100 mass% or less, for example, is 50 mass% or more and 100 mass% or less, for example, 50 mass% or more and 99.9 mass% or less, for example, 50 mass% or more and 98 mass% or less, for example, 70 mass% or more, 95 mass% or less, etc. can be used.
＜その他のエチレン性不飽和単量体＞
　本重合体を構成する非架橋性単量体は、（ａ）成分以外に、これらと共重合可能なその他のエチレン性不飽和単量体（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ル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が挙げられる。（ｂ）成分を含む単量体組成物を重合することにより、本重合体へスルホン酸基及びリン酸基等のカルボキシル基以外のアニオン性基、または非イオン性の構造単位を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が好ましく、バインダーの結着性が優れる点で（メタ）アクリルアミド及びその誘導体等、並びに、ニトリル基含有エチレン性不飽和単量体が好ましい。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が好ましい。 <Other ethylenically unsaturated monomers>
In addition to the component (a), the non-crosslinkable monomer constituting the present polymer includes other ethylenically unsaturated monomers copolymerizable with these (hereinafter also referred to as “component (b)”). Can be included. Examples of the component (b) include an ethylenically unsaturated monomer compound having an anionic group other than a carboxyl group such as a sulfonic acid group and a phosphoric acid group, or a nonionic ethylenically unsaturated monomer. Can be mentioned. (B) An anionic group other than a carboxyl group such as a sulfonic acid group and a phosphoric acid group, or a nonionic structural unit can be introduced into the polymer by polymerizing a monomer composition containing the component (b). it can. Among these, as the component (b), a nonionic ethylenically unsaturated monomer is preferable from the viewpoint of obtaining an electrode having good bending resistance, and (meth) acrylamide is excellent in binder binding properties. And derivatives thereof, and nitrile group-containing ethylenically unsaturated monomers are preferred. In addition, 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), it can exert a strong interaction with the electrode material, Good binding property to the active material can be exhibited. This is preferable because an electrode mixture layer that is firm and has good integrity can be obtained. In particular, an alicyclic structure-containing ethylenically unsaturated monomer is preferred.
　（ｂ）成分の割合は、非架橋性単量体の総量に対して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、１質量％以上、６０質量％以下であってもよく、２質量％以上、５０質量％以下であってもよく、５質量％以上、４０質量％以下であってもよく、１０質量％以上、３０質量％以下であってもよい。また、非架橋性単量体の総量に対して（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。 (B) The ratio of a component can be 0 mass% or more and 90 mass% or less with respect to the total amount of a non-crosslinkable monomer. The proportion of the component (b) may be 1% by mass or more and 60% by mass or less, 2% by mass or more and 50% by mass or less, or 5% by mass or more and 40% by mass or less. 10 mass% or more and 30 mass% or less may be sufficient. In addition, when the component (b) is contained in an amount of 1% by mass or more with respect to the total amount of the non-crosslinkable monomer, the affinity to the electrolytic solution is improved, so that an effect of improving lithium ion conductivity can be expected.
　（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）アクリルアミド等のＮ－アルキル（メタ）アクリルアミド化合物；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－アルコキシアルキル（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。 Examples of (meth) acrylamide derivatives include N-alkyl (meth) acrylamide compounds such as isopropyl (meth) acrylamide and t-butyl (meth) acrylamide; Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl N-alkoxyalkyl (meth) acrylamide compounds such as (meth) acrylamide; and N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide are listed. You may use individually and may be used in combination of 2 or more type.
　ニトリル基含有エチレン性不飽和単量体としては、例えば、（メタ）アクロリニトリル；（メタ）アクリル酸シアノメチル、（メタ）アクリル酸シアノエチル等の（メタ）アクリル酸シアノアルキルエステル化合物；４－シアノスチレン、４－シアノ－α－メチルスチレン等のシアノ基含有不飽和芳香族化合物；シアン化ビニリデン等が挙げられ、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。上記の中でも、ニトリル基含有量が多い点でアクリロニトリルが好ましい。 Examples of the nitrile group-containing ethylenically unsaturated monomer include (meth) acrylonitrile; (meth) acrylic acid cyanoalkyl ester compounds such as (meth) acrylic acid cyanomethyl and (meth) acrylic acid cyanoethyl; 4-cyanostyrene Cyano group-containing unsaturated aromatic compounds such as 4-cyano-α-methylstyrene; vinylidene cyanide and the like, and one of these may be used alone, or two or more may be used in combination. May be used. Among the above, acrylonitrile is preferred because of its high nitrile group content.
　脂環構造含有エチレン性不飽和単量体としては、例えば、（メタ）アクリル酸シクロペンチル、（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、（メタ）アクリル酸ｔ－ブチルシクロヘキシル、（メタ）アクリル酸シクロデシル及び（メタ）アクリル酸シクロドデシル等の脂肪族置換基を有していてもよい（メタ）アクリル酸シクロアルキルエステル；（メタ）アクリル酸イソボルニル、（メタ）アクリル酸アダマンチル、（メタ）アクリル酸ジシクロペンテニル、（メタ）アクリル酸ジシクロペンテニルオキシエチル、（メタ）アクリル酸ジシクロペンタニル、並びに、シクロヘキサンジメタノールモノ（メタ）アクリレート及びシクロデカンジメタノールモノ（メタ）アクリレート等のシクロアルキルポリアルコールモノ（メタ）アクリレート等が挙げられ、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。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い。 Examples of the alicyclic structure-containing ethylenically unsaturated monomer include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth ) (Meth) acrylic acid cycloalkyl ester optionally having an aliphatic substituent such as cyclodecyl acrylate and cyclododecyl (meth) acrylate; isobornyl (meth) acrylate, adamantyl (meth) acrylate, (meth ) Dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and cyclohexanedimethanol mono (meth) acrylate and cyclodecane dimethanol mono (meth) acrylate Cycloalkyl Li alcohol mono (meth) acrylate and the like, may be used one of these alone or may be used in combination of two or more. Among these, a compound having an acryloyl group as a polymerizable functional group is preferable in that a polymer having a long primary chain length is obtained because of a high polymerization rate and the binder has a good binding force.
　その他の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。（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）アクリル酸フェニル、（メタ）アクリル酸フェニルメチル、（メタ）アクリル酸フェニルエチル、（メタ）アクリル酸フェノキシエチル等の芳香族（メタ）アクリル酸エステル化合物；
（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。活物質との密着性及びサイクル特性の観点からは、芳香族（メタ）アクリル酸エステル化合物を好ましく用いることができる。 As other nonionic ethylenically unsaturated monomers, for example, (meth) acrylic acid esters may be used. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. (Meth) acrylic acid alkyl ester compounds;
Aromatic (meth) acrylate compounds such as phenyl (meth) acrylate, phenylmethyl (meth) acrylate, phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate;
(Meth) acrylic acid alkoxyalkyl ester compounds such as (meth) acrylic acid 2-methoxyethyl and (meth) acrylic acid ethoxyethyl;
(Meth) acrylic acid hydroxyalkyl, (meth) acrylic acid hydroxypropyl and (meth) acrylic acid hydroxyalkyl ester compounds such as hydroxybutyl, etc. are used, and one of these is used alone. You may use it in combination of 2 or more types. An aromatic (meth) acrylic acid ester compound can be preferably used from the viewpoints of adhesion with the active material and cycle characteristics.
　リチウムイオン伝導性及びハイレート特性がより向上する観点から、（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エステル等、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。 From the viewpoint of further improving lithium ion conductivity and high-rate characteristics, compounds having an ether bond such as (meth) acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate are preferred. More preferred is 2-methoxyethyl (meth) acrylate.
　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 nonionic ethylenically unsaturated monomers, a compound having an acryloyl group is preferable in that a polymer having a long primary chain length is obtained due to a high polymerization rate, and a binder has a good binding force. In addition, as the nonionic ethylenically unsaturated monomer, a compound having a glass transition temperature (Tg) of a homopolymer of 0 ° C. or less is preferable in that the obtained electrode has good bending resistance.
　本重合体は、当該重合体中に含まれるカルボキシル基の一部又は全部が中和された塩の形態であってもよい。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。 The present polymer may be in the form of a salt in which some or all of the carboxyl groups contained in the polymer are neutralized. Although it does not specifically limit as a kind of salt, 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 Examples include amine salts. Of these, alkali metal salts and magnesium salts are preferred, and alkali metal salts are more preferred because they are less likely to adversely affect battery characteristics.
＜架橋性単量体＞
　本開示における架橋性単量体は、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であって、アリル基以外の重合性不飽和基を少なくとも１個有する単量体である。 <Crosslinkable monomer>
The crosslinkable monomer in the present disclosure includes a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups, and a monomer having a self-crosslinkable functional group such as a hydrolyzable silyl group. And a monomer having at least one polymerizable unsaturated group other than an allyl group.
　上記多官能重合性単量体は、ラジカル重合性不飽和基を分子内に２個以上有し、かつアリル基以外の重合性不飽和基を少なくとも１個有する化合物である。アリル基以外の重合性不飽和基としては、例えば下記一般式（１）及び一般式（２）で表される基等が挙げられる。 The polyfunctional polymerizable monomer is a compound having two or more radically polymerizable unsaturated groups in the molecule and at least one polymerizable unsaturated group other than an allyl group. Examples of the polymerizable unsaturated group other than the allyl group include groups represented by the following general formula (1) and general formula (2).
　ＣＨ２＝Ｃ（Ｒ１）－Ｃ（＝Ｏ）－Ａ－　　　（１）
〔式（１）中、Ｒ１は、水素原子、メチル基、ニトリル基又はハロゲン原子を表す。Ａは、酸素原子、２価の有機基又は単結合を表す。〕
　ＣＨ２＝Ｃ（Ｒ２）－Ｂ－　　　（２）
〔式（２）中、Ｒ２は水素原子、メチル基、ニトリル基又はハロゲン原子を表す。Ｂは置換基を有していてもよいアリーレン基を表す。〕 CH 2 = C (R 1 ) -C (= O) -A- (1)
[Equation (1), R 1 represents a hydrogen atom, a methyl group, a nitrile group or a halogen atom. A represents an oxygen atom, a divalent organic group or a single bond. ]
CH 2 = C (R 2 ) -B- (2)
[In formula (2), R 2 represents a hydrogen atom, a methyl group, a nitrile group or a halogen atom. B represents an arylene group which may have a substituent. ]
　上記一般式（１）中のＲ１が水素原子又はメチル基である場合、Ａが単結合であれば一般式（１）は（メタ）アクリロイル基を表し、Ａが酸素原子であれば（メタ）アクリロイルオキシ基を表す。また、２価の有機基としてのＡは、例えば、ＮＨ、ＮＲ（Ｒはアルキル基を表す）、及びアルキレン基等が挙げられる。尚、本明細書では、一般式（１）中のＲ１が水素原子又はメチル基であり、ＡがＮＨである場合を「（メタ）アクリルアミド基」という。その他、一般式（１）の具体的な基としては、α－シアノアクロイル基、α－ハロゲンアクリロイル基等が挙げられる。 When R 1 in the general formula (1) is a hydrogen atom or a methyl group, if A is a single bond, the general formula (1) represents a (meth) acryloyl group, and if A is an oxygen atom (meta ) Represents an acryloyloxy group. Examples of A as the divalent organic group include NH, NR (R represents an alkyl group), and an alkylene group. In the present specification, the case where R 1 in the general formula (1) is a hydrogen atom or a methyl group and A is NH is referred to as a “(meth) acrylamide group”. Other specific groups of the general formula (1) include α-cyanoacryloyl group, α-halogen acryloyl group and the like.
　上記一般式（１）で表される基を有する多官能重合性単量体の具体的な化合物としては、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、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の多価アルコールのジ（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、ジペンタエリスリトールペンタ及びヘキサ（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；ジビニルベンゼン等の芳香族ジビニル化合物；（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）エチル等の（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を挙げることができる。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。 Specific examples of the polyfunctional polymerizable monomer having the group represented by the general formula (1) include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and 1,6-hexanediol. Di (meth) acrylates of polyhydric alcohols such as di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate; trimethylolpropane tri (Meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, Tri (meth) acrylates of trihydric or higher polyhydric alcohols such as pentaerythritol penta and hexa (meth) acrylate, poly (meth) acrylates such as tetra (meth) acrylate; bisamides such as methylene bisacrylamide and hydroxyethylene bisacrylamide Aromatic divinyl compounds such as divinylbenzene; allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, 2- (2-vinyl) (meth) acrylate And compounds having both a (meth) acryloyl group and an alkenyl group, such as (roxyethoxy) ethyl. These compounds may be used alone or in combination of two or more.
　上記一般式（２）の具体的な基としては、スチリル基等が挙げられる。これらの基を有する多官能重合性単量体の具体的な化合物としては、ジビニルベンゼン、ジビニルナフタレン等が挙げられる。 Specific examples of the general formula (2) include a styryl group. Specific examples of the polyfunctional polymerizable monomer having these groups include divinylbenzene and divinylnaphthalene.
　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 monomers, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate, and the like. Is mentioned. These compounds can 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、アリル基以外の重合性不飽和基及び加水分解性シリル基を有する単量体であれば、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 monomer having a polymerizable unsaturated group other than an allyl group and a hydrolyzable silyl group. For example, vinyl silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane; silyl such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, and methyldimethoxysilylpropyl acrylate Group-containing acrylic acid esters; silyl group-containing methacrylates such as trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate; trimethoxysilylpropyl vinyl ether, etc. Silyl group-containing vinyl ethers; and silyl group-containing vinyl esters such as vinyl trimethoxysilylundecanoate.
　本重合体において、上記架橋性単量体の使用量は、特に限定されるものではないが、非架橋性単量体の総量１００質量部に対して好ましくは０．１質量部以上であり、より好ましくは０．５質量部以上である。架橋性単量体の使用量は、例えば１．０質量部以上であってもよく、また例えば２．０質量部以上であってもよく、また例えば３．０質量部以上であってもよい。使用量の上限値は、特に限定されるものではないが、例えば２０質量部以下であってもよく、また例えば１５質量部以下であってもよく、また例えば１０質量部以下であってもよい。さらに例えば、５質量部以下であってもよい。また例えば３質量部以下であってもよい。使用量の範囲については、これらの上限値及び下限値を組み合せることができ、例えば０．１質量部以上２０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０．５質量部以上１０質量部以下である。架橋性単量体の使用量が０．１質量部以上であれば結着性及び合剤層スラリーの安定性がより良好となる点で好ましい。２０質量部以下であれば、重合体の安定性が高くなる傾向がある。
　同様に、上記架橋性単量体の使用量は、非架橋性単量体の総量に対して０．０２～２．５モル％であることが好ましく、０．０３～１．５モル％であることがより好ましい。 In the present polymer, the amount of the crosslinkable monomer used is not particularly limited, but is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the total amount of non-crosslinkable monomers, More preferably, it is 0.5 mass part or more. The amount of the crosslinkable monomer used may be, for example, 1.0 part by mass or more, may be 2.0 parts by mass or more, and may be, for example, 3.0 parts by mass or more. . The upper limit of the amount used is not particularly limited, but may be, for example, 20 parts by mass or less, may be, for example, 15 parts by mass or less, and may be, for example, 10 parts by mass or less. . Further, for example, it may be 5 parts by mass or less. For example, it may be 3 parts by mass or less. About the range of usage-amount, these upper limit and lower limit can be combined, for example, 0.1 to 20 parts by mass, for example, 0.1 to 10 parts by mass, Moreover, it is 0.5 mass part or more and 10 mass parts or less, for example. If the use amount of the crosslinkable monomer is 0.1 parts by mass or more, the binding property and the stability of the mixture layer slurry are preferable. If it is 20 parts by mass or less, the stability of the polymer tends to increase.
Similarly, the amount of the crosslinkable monomer used is preferably 0.02 to 2.5 mol%, and preferably 0.03 to 1.5 mol% with respect to the total amount of the non-crosslinkable monomer. More preferably.
　本重合体は、アリル基以外の重合性不飽和基を有さない架橋性単量体のみにより架橋した架橋重合体に比較して、粒子表面の架橋密度を低くすることができる。この結果、水中での本重合体の表面部分の膨潤度が比較的高く、活物質や集電体との接着面積が確保されるため、本重合体を含むバインダーは良好な結着性を示すと考えられる。ただし、上記の機構は推定であり、本開示の範囲を限定するものではない。 This polymer can lower the crosslinking density on the particle surface as compared with a crosslinked polymer crosslinked only by a crosslinking monomer having no polymerizable unsaturated group other than an allyl group. As a result, the degree of swelling of the surface portion of the polymer in water is relatively high, and a bonding area with the active material and the current collector is ensured. Therefore, the binder containing the polymer exhibits good binding properties. it is conceivable that. However, the above mechanism is an estimation and does not limit the scope of the present disclosure.
＜架橋重合体の粒子径＞
　本重合体は、合剤層組成物において、当該重合体が大粒径の塊（二次凝集体）として存在することなく、適度な粒径を有する水膨潤粒子として良好に分散していることが、当該架橋重合体を含むバインダーが良好な結着性能を発揮し得るため好ましい。 <Particle diameter of crosslinked polymer>
In the mixture layer composition, the polymer is well dispersed as water-swelling particles having an appropriate particle size without the polymer being present as a large particle size lump (secondary aggregate). However, since the binder containing the said crosslinked polymer can exhibit favorable binding performance, it is preferable.
　上記架橋重合体又はその塩は、該架橋重合体が有するカルボキシル基に基づく中和度が８０～１００モル％であるものを水中に分散させた際の粒子径（水膨潤粒子径）が、体積基準メジアン径で０．１μｍ以上、１０．０μｍ以下の範囲にあることが好ましい。上記粒子径のより好ましい範囲は０．１μｍ以上、８．０μｍ以下であり、さらに好ましい範囲は０．１μｍ以上、７．０μｍ以下であり、一層好ましい範囲は０．２μｍ以上、５．０μｍ以下であり、より一層好ましい範囲は０．５μｍ以上、３．０μｍ以下である。また、好ましい範囲は、０．１μｍ以上２．０μｍ以下である。粒子径が０．１μｍ以上、１０．０μｍ以下の範囲であれば、合剤層組成物中において好適な大きさで均一に存在するため、合剤層組成物の安定性が高く、優れた結着性を発揮することが可能となる。粒子径が１０．０μｍ以下を超えると、上記の通り結着性が不十分となる虞がある。また、平滑性な塗面が得られにくい点で、塗工性が不十分となる虞がある。一方、粒子径が０．１μｍ未満の場合には、安定製造性の観点において懸念される。
　なお、上記水膨潤粒子径は、本明細書実施例に記載の方法により測定することができる。 The crosslinked polymer or a salt thereof has a particle size (water-swelled particle size) when dispersed in water having a neutralization degree of 80 to 100 mol% based on the carboxyl group of the crosslinked polymer. The reference median diameter is preferably in the range of 0.1 μm or more and 10.0 μm or less. A more preferable range of the particle diameter is 0.1 μm or more and 8.0 μm or less, a further preferable range is 0.1 μm or more and 7.0 μm or less, and a more preferable range is 0.2 μm or more and 5.0 μm or less. There is an even more preferable range of 0.5 μm or more and 3.0 μm or less. Moreover, a preferable range is 0.1 micrometer or more and 2.0 micrometers or less. If the particle size is in the range of 0.1 μm or more and 10.0 μm or less, the mixture layer composition is uniformly present in a suitable size, so that the mixture layer composition has high stability and excellent binding. It becomes possible to demonstrate wearability. If the particle diameter exceeds 10.0 μm or less, the binding property may be insufficient as described above. Moreover, there exists a possibility that coating property may become inadequate at the point which cannot obtain a smooth coating surface. On the other hand, when the particle diameter is less than 0.1 μm, there is a concern from the viewpoint of stable productivity.
In addition, the said water swelling particle diameter can be measured by the method as described in an Example of this specification.
　架橋重合体が未中和若しくは中和度８０モル％未満の場合は、アルカリ金属水酸化物等により中和度８０～１００モル％に中和し、水中に分散させた際の粒子径を測定すればよい。一般に、架橋重合体又はその塩は、粉末または溶液（分散液）の状態では一次粒子が会合、凝集した塊状粒子として存在する場合が多い。上記の水分散させた際の粒子径が上記範囲である場合、当該架橋重合体又はその塩は極めて優れた分散性を有するものであり、中和度８０～１００モル％に中和して水分散することにより塊状粒子が解れ、ほぼ一次粒子の分散体、若しくは２次凝集体であっても、その粒子径が０．１～１０．０μｍの範囲内にある、安定な分散状態を形成するものである。 If the crosslinked polymer is unneutralized or has a neutralization degree of less than 80 mol%, the particle diameter is measured when neutralized with an alkali metal hydroxide to a neutralization degree of 80 to 100 mol% and dispersed in water. do it. In general, a crosslinked polymer or a salt thereof often exists as aggregated particles in which primary particles are associated and aggregated in a powder or solution (dispersion) state. When the particle size when dispersed in water is within the above range, the crosslinked polymer or salt thereof has extremely excellent dispersibility, and is neutralized to a neutralization degree of 80 to 100 mol% to give water. By dispersing, the aggregated particles are released, and even if it is a primary particle dispersion or secondary aggregate, a stable dispersion state is formed in which the particle diameter is in the range of 0.1 to 10.0 μm. Is.
　水膨潤粒子径の体積基準メジアン径を個数基準メジアン径で除した値である粒子径分布は、結着性及び塗工性の観点から好ましくは１０以下であり、より好ましくは５．０以下であり、さらに好ましくは３．０以下であり、なお好ましくは２．０以下であり、一層好ましくは１．５以下である。上記粒子径分布の下限値は、通常は１．０である。 The particle size distribution, which is a value obtained by dividing the volume-based median diameter of the water-swelling particle diameter by the number-based median diameter, is preferably 10 or less, more preferably 5.0 or less, from the viewpoints of binding properties and coatability. Yes, more preferably 3.0 or less, still more preferably 2.0 or less, and even more preferably 1.5 or less. The lower limit of the particle size distribution is usually 1.0.
　また、架橋重合体又はその塩の乾燥時における粒子径（乾燥粒子径）は、体積基準メジアン径で０．０３μｍ以上、３μｍ以下の範囲にあることが好ましい。上記粒子径のより好ましい範囲は０．１μｍ以上、１μｍ以下であり、さらに好ましい範囲は０．３μｍ以上、０．８μｍ以下である。 Further, the particle diameter (dry particle diameter) of the crosslinked polymer or salt thereof when dried is preferably in the range of 0.03 μm or more and 3 μm or less in terms of volume-based median diameter. A more preferable range of the particle diameter is 0.1 μm or more and 1 μm or less, and a further preferable range is 0.3 μm or more and 0.8 μm or less.
　本重合体又はその塩は、合剤層組成物中において、中和度が２０モル％以上となるように、エチレン性不飽和カルボン酸単量体由来のカルボキシル基等の酸基が中和され、塩の態様として用いられることが好ましい。上記中和度は、より好ましくは５０モル％であり、さらに好ましくは６０モル％以上であり、一層好ましくは７０モル％以上であり、より一層好ましくは８０モル％以上であり、特に好ましくは８５モル％以上である。中和度の上限値は１００モル％であり、９８モル％であってもよく９５モル％であってもよい。中和度の範囲は、上記下限値及び上限値を適宜組合せることができ、例えば、５０モル％以上１００モル％以下であってもよく、７０モル％以上１００モル％以下であってもよく、８０モル％以上１００モル％以下であってもよい。中和度が２０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。本明細書では、上記中和度は、カルボキシル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、中和度は架橋重合体又はその塩を、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 mixture layer composition, the present polymer or a salt thereof is neutralized with an acid group such as a carboxyl group derived from an ethylenically unsaturated carboxylic acid monomer so that the degree of neutralization is 20 mol% or more. It is preferably used as a salt embodiment. The degree of neutralization is more preferably 50 mol%, still more preferably 60 mol% or more, still more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 85 mol%. More than mol%. The upper limit of the degree of neutralization is 100 mol%, which may be 98 mol% or 95 mol%. The range of the degree of neutralization can be appropriately combined with the above lower limit value and upper limit value, for example, may be 50 mol% or more and 100 mol% or less, or 70 mol% or more and 100 mol% or less. 80 mol% or more and 100 mol% or less. When the degree of neutralization is 20 mol% or more, water swellability is good and a dispersion stabilizing effect is easily obtained. In this specification, the said neutralization degree can be computed by calculation from the preparation value of the monomer which has acid groups, such as a carboxyl group, and the neutralizing agent used for neutralization. The degree of neutralization is measured by IR measurement of the crosslinked polymer or salt thereof, and the powder after drying treatment 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═ of the carboxylate. This can be confirmed from the intensity ratio of the peak derived from the O group.
＜本重合体又はその塩の製造方法＞
　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。 <Method for producing the present polymer or a salt thereof>
For this polymer, known polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, emulsion polymerization and the like can be used, but precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) are considered in terms of productivity. ) Is preferred. A heterogeneous polymerization method such as precipitation polymerization, suspension polymerization, and emulsion polymerization is preferable in that better performance can be obtained with respect to binding properties and the like, and precipitation polymerization is more preferable.
Precipitation polymerization is a method for producing a polymer by carrying out a polymerization reaction in a solvent that dissolves an unsaturated monomer as a raw material but does not substantially dissolve the produced polymer. As the polymerization proceeds, the polymer particles become larger due to aggregation and growth, and a dispersion of polymer particles in which primary particles of several tens to several hundreds of nm are secondarily aggregated to several μm to several tens of μm is obtained. A dispersion stabilizer can also be used to control the particle size of the polymer.
In addition, the secondary aggregation can be suppressed by selecting a dispersion stabilizer, a polymerization solvent, and the like. In general, precipitation polymerization in which secondary aggregation is suppressed is also called dispersion polymerization.
　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。 In the case of precipitation polymerization, a solvent selected from water and various organic solvents can be used as the polymerization solvent in consideration of the type of monomer 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. Or you may use as a mixed solvent of these and water. In this 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 adhesion to the reactor are small, the polymerization stability is good, and the precipitated polymer fine particles are difficult to agglomerate (or even if secondary agglomeration occurs, they can be dissolved in an aqueous medium). Methyl ethyl ketone and acetonitrile are preferred from the standpoints that a polymer having a small chain transfer constant and a high degree of polymerization (primary chain length) can be obtained, and that the operation can be easily performed during the process 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０．０５～２０．０質量％であり、より好ましくは０．１～１０．０質量％、さらに好ましくは０．１～５．０質量％であり、一層好ましくは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、２０．０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 order to allow the neutralization reaction to proceed stably and quickly in the process neutralization, it is preferable to add a small amount of a highly polar solvent to the polymerization solvent. Such a highly polar solvent preferably includes water and methanol. The amount of the highly polar solvent used is preferably 0.05 to 20.0% by mass based on the total mass of the medium, more preferably 0.1 to 10.0% by mass, and even more preferably 0.1 to 5%. 0.0 mass%, more preferably 0.1 to 1.0 mass%. If the ratio of the highly polar solvent is 0.05% by mass or more, the effect on the neutralization reaction is recognized, and if it is 20.0% 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 monomers such as acrylic acid, when a highly polar solvent is added, the polymerization rate is improved, and a polymer having a long primary chain is easily obtained. Among the highly polar solvents, water is particularly preferable because it has the effect of improving the polymerization rate.
　本重合体又はその塩の製造においては、非架橋性単量体及び架橋性単量体を含む単量体成分を重合する重合工程を備えることが好ましい。非架橋性単量体としては、該非架橋性単量体の総量に対し、エチレン性不飽和カルボン酸単量体を５０質量％以上１００質量％以下含むことが好ましい。エチレン性不飽和カルボン酸単量体としては、本明細書中、架橋重合体の構成単量体の説明において（ａ）成分として挙げた化合物を使用することができる。非架橋性単量体は、エチレン性不飽和カルボン酸単量体以外にもその他のエチレン性不飽和単量体を０質量％以上５０質量％以下含んでいてもよい。その他のエチレン性不飽和単量体としては、本明細書中、架橋重合体の構成単量体の説明において（ｂ）成分として挙げた化合物を使用することができる。重合工程により得られた重合体には、上記（ａ）成分及び上記（ｂ）成分に由来する構造単位がそれらの使用量に応じた割合で導入される。
　一方、架橋性単量体としては、本重合体における架橋性単量体として挙げた、アリル基以外の重合性不飽和基を少なくとも１個有する単量体を使用することができる。 The production of the present polymer or a salt thereof preferably includes a polymerization step of polymerizing a monomer component containing a non-crosslinkable monomer and a crosslinkable monomer. As a non-crosslinkable monomer, it is preferable that 50 to 100 mass% of ethylenically unsaturated carboxylic acid monomers are included with respect to the total amount of the non-crosslinkable monomer. As the ethylenically unsaturated carboxylic acid monomer, the compounds listed as the component (a) in the description of the constituent monomer of the crosslinked polymer in the present specification can be used. The non-crosslinkable monomer may contain 0% by mass or more and 50% by mass or less of other ethylenically unsaturated monomers in addition to the ethylenically unsaturated carboxylic acid monomer. As other ethylenically unsaturated monomers, the compounds mentioned as the component (b) in the description of the constituent monomers of the crosslinked polymer in this specification can be used. In the polymer obtained by the polymerization step, structural units derived from the component (a) and the component (b) are introduced at a ratio corresponding to the amount of use.
On the other hand, as the crosslinkable monomer, a monomer having at least one polymerizable unsaturated group other than an allyl group, which is exemplified as the crosslinkable monomer in the present polymer, can be used.
　重合時の単量体濃度については、より一次鎖長の長い重合体を得る観点から高い方が好ましい。ただし、単量体濃度が高すぎると、重合体粒子の凝集が進行し易い他、重合熱の制御が困難となり重合反応が暴走する虞がある。このため、例えば沈殿重合法の場合、重合開始時の単量体濃度は、２～４０質量％程度の範囲が一般的であり、好ましくは５～４０質量％の範囲である。
　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 monomer concentration at the time of polymerization is preferably higher from the viewpoint of obtaining a polymer having a longer primary chain length. However, if the monomer concentration is too high, the aggregation of the polymer particles tends to proceed and the control of the polymerization heat becomes difficult and the polymerization reaction may run away. Therefore, for example, in the case of precipitation polymerization, the monomer concentration at the start of polymerization is generally in the range of about 2 to 40% by mass, preferably in the range of 5 to 40% by mass.
In the present specification, the “monomer concentration” refers to the monomer concentration in the reaction solution at the time of starting the polymerization.
　本重合体は、塩基化合物の存在下に重合反応を行うことにより製造してもよい。塩基化合物存在下において重合反応を行うことにより、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。単量体濃度は、１３．０質量％以上であってもよく、好ましくは１５．０質量％以上であり、より好ましくは１７．０質量％以上であり、更に好ましくは１９．０質量％以上であり、一層好ましくは２０．０質量％以上である。単量体濃度はなお好ましくは２２．０質量％以上であり、より一層好ましくは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、本重合体が架橋重合体である場合には、一次鎖長の長い重合体を製造することができる。 The present polymer may be produced by performing a polymerization reaction in the presence of a base compound. By carrying out the polymerization reaction in the presence of the base compound, the polymerization reaction can be carried out stably even under high monomer concentration conditions. The monomer concentration may be 13.0% by mass or more, preferably 15.0% by mass or more, more preferably 17.0% by mass or more, and further preferably 19.0% by mass or more. And more preferably 20.0% by mass or more. The monomer concentration is still preferably 22.0% by mass or more, and more preferably 25.0% by mass or more. Generally, the higher the monomer concentration during polymerization, the higher the molecular weight, and when this polymer is a crosslinked polymer, a polymer having a long primary chain length can be produced.
　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、沈殿重合では上記の通り概ね４０％程度、懸濁重合では概ね５０％程度、乳化重合では概ね７０％程度である。 The upper limit of the monomer concentration varies depending on the type of monomer and solvent used, the polymerization method and various polymerization conditions, etc., but if the heat of polymerization reaction can be removed, precipitation polymerization is as described above. About 40%, about 50% for suspension polymerization, and about 70% for emulsion polymerization.
　上記塩基化合物は、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何れを用いてもよい。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。また、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。
　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。
　有機塩基化合物としては、アンモニア、並びに、モノエチルアミン、ジエチルアミン及びトリエチルアミン、トリ－ｎ－オクチルアミン等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。中でも、重合安定性及び得られる重合体又はその塩を含むバインダーの結着性の観点から、有機アミン化合物が好ましい。 The basic compound is a so-called alkaline compound, and any of an inorganic basic compound and an organic basic compound may be used. By carrying out the polymerization reaction in the presence of the base compound, the polymerization reaction can be carried out stably even under high monomer concentration conditions, for example, exceeding 13.0% by mass. In addition, a polymer obtained by polymerization at such a high monomer concentration has a high molecular weight (because of a long primary chain length) and is excellent in binding properties.
Examples of the inorganic base compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide. Among these, 1 type (s) or 2 or more types can be used.
Examples of the organic base compound include ammonia and organic amine compounds such as monoethylamine, diethylamine and triethylamine, and tri-n-octylamine, and one or more of them can be used. Among these, an organic amine compound is preferable from the viewpoints of polymerization stability and binding properties of a binder containing the obtained polymer or a salt thereof.
　塩基化合物の使用量は、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４．０モル％以下の範囲とすることが好ましい。塩基化合物の使用量がこの範囲であれば、重合反応を円滑に行うことができる。使用量は、０．０５モル％以上４．０モル％以下であってもよく、０．１モル％以上４．０モル％以下であってもよく、０．１モル％以上３．０モル％以下であってもよく、０．１モル％以上２．０モル％以下であってもよい。
　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。 The amount of the base compound used is preferably in the range of 0.001 mol% to 4.0 mol% with respect to the ethylenically unsaturated carboxylic acid monomer. If the usage-amount of a basic compound is this range, a polymerization reaction can be performed smoothly. The amount used may be 0.05 mol% or more and 4.0 mol% or less, 0.1 mol% or more and 4.0 mol% or less, or 0.1 mol% or more and 3.0 mol% or less. % Or less, or 0.1 mol% or more and 2.0 mol% or less.
In addition, in this specification, the usage-amount of a base compound 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 base compound used is not taken into consideration.
　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。 The polymerization initiator may be a known polymerization initiator such as an azo compound, an organic peroxide, or an inorganic peroxide, but is 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, or the like so as to obtain an appropriate radical generation amount. In order to obtain a crosslinked polymer having a long primary chain length, it is preferable to set conditions so that the amount of radicals generated is reduced within a range in which 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 compound 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 these 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 (manufactured by NOF Corporation, trade name “Pertetra A”), 1,1-di (t- Hexylperoxy) cyclohexane (same as “Perhexa HC”), 1,1-di (t-butylperoxy) cyclohexane (same as “PerhexaC”), n-butyl-4,4-di (t-butylperoxy) Valerate ("Perhexa V"), 2,2-di (t-butylperoxy) butane ("Perhexa 22"), t-butyl hydroperoxide ("Perbutyl H"), cumene hydroperoxide (Japan) Made by Oil Co., Ltd., trade name “Park Mill H”), 1,1,3,3-tetramethylbutyl hydroperoxide (“Perocta H”), t-butyl cumyl peroxide (same as above) Perbutyl C "), di-t-butyl peroxide (" perbutyl D "), di-t-hexyl peroxide (" perhexyl D "), di (3,5,5-trimethylhexanoyl) peroxide ( "Parroyl 355"), dilauroyl peroxide ("Parroyl L"), bis (4-t-butylcyclohexyl) peroxydicarbonate ("Parroyl TCP"), di-2-ethylhexyl peroxydicarbonate ( "Parroyl OPP"), di-sec-butyl peroxydicarbonate ("Parroyl SBP"), cumyl peroxyneodecanoate ("Parcumyl ND"), 1,1,3,3-tetramethylbutyl Peroxyneodecanoate ("Perocta ND"), t-hexylperoxyneodeca (Perhexyl ND), t-butyl peroxyneodecanoate (Perbutyl ND), t-butyl peroxyneoheptanoate (Perbutyl NHP), t-hexyl peroxypivalate (“Perhexyl PV”), t-butyl peroxypivalate (“Perbutyl PV”), 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane (“Perhexa 250”), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate ("PeroctaO"), t-hexylperoxy-2-ethylhexanoate ("PerhexylO"), t- Butyl peroxy-2-ethylhexanoate ("Perbutyl O"), t-butyl peroxylaurate ("Perbutyl L"), t-butyl Tilperoxy-3,5,5-trimethylhexanoate ("Perbutyl 355"), t-hexyl peroxyisopropyl monocarbonate ("Perhexyl I"), t-butyl peroxyisopropyl monocarbonate ("Perbutyl I") ), T-butyl peroxy-2-ethylhexyl monocarbonate (same as “perbutyl E”), t-butyl peroxyacetate (same as “perbutyl A”), t-hexyl peroxybenzoate (same as “perhexyl Z”) and t -Butyl peroxybenzoate ("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, and ammonium persulfate.
In the case of redox initiation, sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, sulfurous acid gas (SO 2 ), ferrous sulfate and the like can be used as a reducing agent.
　重合開始剤の好ましい使用量は、用いる単量体成分の総量を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 use amount of the polymerization initiator is, for example, 0.001 to 2 parts by mass, for example 0.005 to 1 part by mass when the total amount of the monomer components to be used is 100 parts by mass, For example, it is 0.01 to 0.1 parts by mass. When the amount of the polymerization initiator used is 0.001 part by mass or more, the polymerization reaction can be stably performed, and when it is 2 parts by mass or less, a polymer having a long primary chain length is easily obtained.
　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。 The polymerization temperature is preferably 0 to 100 ° C., more preferably 20 to 80 ° C., although 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 polymerization reaction. The polymerization time is preferably 1 minute to 20 hours, and more preferably 1 hour to 10 hours.
　重合工程を経て得られた本重合体分散液は、乾燥工程において減圧及び／又は加熱処理等を行い溶媒留去することにより、目的とする本重合体を粉末状態で得ることができる。この際、上記乾燥工程の前に、未反応単量体（及びその塩）、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、遠心分離及び濾過等の固液分離工程、水、メタノー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良好な性能を示す。 The polymer dispersion obtained through the polymerization step can be obtained in a powder state by subjecting the polymer dispersion to a reduced pressure and / or heat treatment in the drying step and distilling off the solvent. At this time, prior to the drying step, for the purpose of removing unreacted monomers (and salts thereof), impurities derived from the initiator, etc., following the polymerization step, a solid-liquid separation step such as centrifugation and filtration, water, It is preferable to provide a washing step using methanol or the same solvent as the polymerization solvent. When equipped with the above washing step, even if this polymer is secondary agglomerated, it is easy to unravel at the time of use, and the remaining unreacted monomer is removed, so that the binding property and battery characteristics are also good. Performance.
　本製造方法では、重合工程により得られた重合体分散液にアルカリ化合物を添加して重合体を中和（以下、「工程中和」ともいう）した後、乾燥工程で溶媒を除去してもよい。また、上記工程中和の処理を行わずに本重合体の粉末を得た後、電極合剤層スラリーを調製する際に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）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。 In this production method, an alkali compound is added to the polymer dispersion obtained in the polymerization step to neutralize the polymer (hereinafter also referred to as “step neutralization”), and then the solvent is removed in the drying step. Good. In addition, after obtaining the powder of the present polymer without performing the above-described process neutralization, an alkali compound is added when preparing the electrode mixture layer slurry to neutralize the polymer (hereinafter, May also be referred to as “sum”. Among the above, the process neutralization is preferable because the secondary aggregate tends to be easily broken.
＜二次電池電極合剤層用組成物＞
　本発明の二次電池電極合剤層用組成物は、本重合体又はその塩を含有するバインダー、活物質及び水を含む。
　本発明の電極合剤層組成物における本重合体又はその塩の使用量は、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、架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 mixture layer>
The composition for a secondary battery electrode mixture layer of the present invention includes a binder containing the present polymer or a salt thereof, an active material, and water.
The usage-amount of this polymer or its salt in the electrode mixture layer composition of this invention is 0.1 to 20 mass% with respect to the whole quantity of an active material, for example. 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 properties may not be obtained. Further, the dispersion stability of the active material or the like becomes insufficient, and the uniformity of the formed mixture layer may be lowered. On the other hand, when the usage amount of the base polymer and its salt exceeds 20% by mass, the electrode mixture layer composition may have a high viscosity and the coating property to the current collector may be lowered. As a result, bumps and irregularities are generated in the obtained mixture layer, which may adversely affect the electrode characteristics.
　本重合体及びその塩の使用量が上記範囲内であれば、分散安定性に優れた組成物が得られるとともに、集電体への密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、本橋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。 If the amount of the present polymer and its salt used is within the above range, a composition having excellent dispersion stability can be obtained, and a mixture layer with extremely high adhesion to the current collector can be obtained. As a result, the durability of the battery is improved. Furthermore, the present bridge polymer and its salt show sufficiently high binding properties even in a small amount (for example, 5% by mass or less) with respect to the active material, and have a carboxy anion, so that the interface resistance is small and the high rate property is excellent. An electrode is obtained.
　上記活物質の内、正極活物質としては遷移金属酸化物のリチウム塩を用いることができ、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。 Among the active materials, a lithium salt of a transition metal oxide can be used as the positive electrode active material. For example, a layered rock salt type and a spinel type lithium-containing metal oxide 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 {Li (Ni 1-ab Co a Al b )} and the like. Examples of the spinel positive electrode active material include lithium manganate. In addition to oxides, phosphates, silicates, sulfur and the like are used, and examples of the phosphate include olivine type lithium iron phosphate. As the positive electrode active material, one of the above may be used alone, or two or more may be used in combination as a mixture or a 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ル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。 In addition, when the positive electrode active material containing a layered rock salt type lithium-containing metal oxide is dispersed in water, the dispersion exhibits alkalinity by exchanging lithium ions on the active material surface with hydrogen ions in water. For this reason, there exists a possibility that the aluminum foil (Al) etc. which are general collector materials for positive electrodes may be corroded. In such a case, it is preferable to neutralize the alkali content eluted from the active material by using the unneutralized or partially neutralized polymer as a binder. In addition, the amount of unneutralized or partially neutralized polymer used should be such that the amount of carboxyl groups that are not neutralized in the polymer is equal to or greater 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 any positive electrode active material has low electrical conductivity, it is common to add a conductive auxiliary agent. Examples of the conductive assistant include carbon-based materials such as carbon black, carbon nanotube, carbon fiber, graphite fine powder, and carbon fiber. Among these, carbon black, carbon nanotube, and carbon fiber are easy to obtain excellent conductivity. Are preferred. Moreover, as carbon black, ketjen black and acetylene black are preferable. As the conductive assistant, one of the above may be used alone, or two or more may be used in combination. From the viewpoint of achieving both conductivity and energy density, the use amount of the conductive auxiliary agent can be, for example, 0.2 to 20% by mass with respect to the total amount of the active material, and for example, 0.2 to 10%. It can be made into the mass%. The positive electrode active material may be a surface coated with a conductive carbon-based material.
　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 materials, lithium metals, lithium alloys, metal oxides, and the like, and one or more of them can 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, graphite such as natural graphite and artificial graphite, and Hard carbon is more preferable. In the case of graphite, spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferred particle size range is, for example, 1 to 20 μm, and for example, 5 to 15 μm. In order to increase the energy density, a metal or metal oxide that can occlude 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 an active material composed of silicon-based materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter referred to as “silicon-based active material”). Can be used. However, the silicon-based active material has a high capacity, but has a large volume change due to charge / discharge. For this reason, it is preferable to use together with the carbon-based active material. In this case, if the compounding amount of the silicon-based active material is large, the electrode material may be collapsed and the cycle characteristics (durability) may be greatly reduced. From such a point of view, when a silicon-based active material is used in combination, the amount used is, for example, 60% by mass or less, for example, 30% by mass or less with respect to the carbon-based active material.
　本重合体を含むバインダーは、当該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、本開示の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)) derived from the ethylenically unsaturated carboxylic acid monomer. Here, the component (a) has a high affinity for the silicon-based active material and exhibits good binding properties. For this reason, the binder of the present disclosure exhibits an excellent binding property even when a high-capacity type active material containing a silicon-based active material is used, and thus is effective for improving the durability of the obtained electrode. It is considered a thing.
　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 additive. When a conductive additive is added for the purpose of further reducing the resistance, the amount used is, for example, 10% by mass or less, for example, 5% by weight or less with respect to the total amount of the active material from the viewpoint of energy density. It is.
　二次電池電極合剤層用組成物がスラリー状態の場合、活物質の使用量は、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 for the secondary battery electrode mixture layer is in a slurry state, the amount of the active material used is, for example, in the range of 10 to 75% by mass, for example, 30 to 65% by mass with respect to the total amount of the composition. Range. When the amount of the active material used is 10% by mass or more, the migration of the binder and the like is suppressed, and the medium drying cost is advantageous. On the other hand, if it is 75 mass% or less, the fluidity | liquidity and coating property of a composition can be ensured, and a uniform mixture layer can be formed.
　また、湿粉状態で電極合剤層用組成物を調製する場合、活物質の使用量は、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 preparing the composition for an electrode mixture layer in a wet powder state, the amount of the active material used is, for example, in the range of 60 to 97% by mass relative to the total amount of the composition, and for example, 70 to 90 It is the range of mass%. Further, from the viewpoint of energy density, it is preferable that the non-volatile components other than the active material such as the binder and the conductive assistant are as small as possible within a range in which necessary binding properties and conductivity are ensured.
　二次電池電極合剤層用組成物は、媒体として水を使用する。また、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 for the secondary battery electrode mixture layer uses water as a medium. In addition, for the purpose of adjusting the properties and drying properties of the composition, water-soluble organic solvents such as lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, tetrahydrofuran, N-methylpyrrolidone, etc. It is good also as a mixed solvent. The ratio of water in the mixed medium is, for example, 50% by mass or more, and for example, 70% by mass or more.
　電極合剤層用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 electrode mixture layer composition is in a slurry state that can be applied, the content of the medium containing water in the entire composition is determined from the viewpoints of slurry coating properties, energy costs required for drying, and productivity. From, for example, it can be in the range of 25-90% by mass, and can be, for example, 35-70% by mass. In the case of a pressable wet powder state, the content of the medium can be set in the range of 3 to 40% by mass, for example, from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of ˜30% by mass.
　本開示のバインダーは、本重合体又はその塩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 of the present disclosure may be composed only of the present polymer or a salt thereof, but other binders such as styrene / butadiene latex (SBR), acrylic latex, and polyvinylidene fluoride latex are also available. You may use an ingredient together. When other binder components are used in combination, the amount used can be, for example, 0.1 to 5% by mass or less, for example, 0.1 to 2% by mass or less based on the active material. For example, it can be 0.1 to 1% by mass or less. When the amount of other binder components used exceeds 5% by mass, the resistance increases and the high rate characteristics may be insufficient. Among these, styrene / butadiene latex is preferable in terms of excellent balance between binding properties and bending resistance.
　上記スチレン／ブタジエン系ラテックスとは、スチレン等の芳香族ビニル単量体に由来する構造単位及び１，３－ブタジエン等の脂肪族共役ジエン系単量体に由来する構造単位を有する共重合体の水系分散体を示す。上記芳香族ビニル単量体としては、スチレンの他にα－メチルスチレン、ビニルトルエン、ジビニルベンゼン等が挙げられ、これらの内の１種又は２種以上を用いることができる。上記共重合体中における上記芳香族ビニル単量体に由来する構造単位は、主に結着性の観点から、例えば、２０～６０質量％の範囲とすることができ、また例えば、３０～５０質量％の範囲とすることができる。 The styrene / butadiene latex is a copolymer having a structural unit derived from an aromatic vinyl monomer such as styrene and a structural unit derived from an aliphatic conjugated diene monomer such as 1,3-butadiene. An aqueous dispersion is shown. Examples of the aromatic vinyl monomer include α-methylstyrene, vinyltoluene, divinylbenzene and the like in addition to styrene, and one or more of these can be used. The structural unit derived from the aromatic vinyl monomer in the copolymer can be, for example, in the range of 20 to 60% by mass mainly from the viewpoint of binding properties, and for example, 30 to 50%. It can be made into the range of the mass%.
　上記脂肪族共役ジエン系単量体としては、１，３－ブタジエンの他に２－メチル－１，３－ブタジエン、２，３－ジメチル－１，３－ブタジエン、２－クロロ－１，３－ブタジエン等が挙げられ、これらの内の１種又は２種以上を用いることができる。上記共重合体中における上記脂肪族共役ジエン系単量体に由来する構造単位は、バインダーの結着性及び得られる電極の柔軟性が良好なものとなる点で、例えば、３０～７０質量％の範囲とすることができ、また例えば、４０～６０質量％の範囲とすることができる。 Examples of the aliphatic conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. Butadiene and the like can be mentioned, and one or more of these can be used. The structural unit derived from the aliphatic conjugated diene monomer in the copolymer is, for example, 30 to 70% by mass in that the binder binding property and the flexibility of the resulting electrode are good. For example, it can be in the range of 40 to 60% by mass.
　スチレン／ブタジエン系ラテックスは、上記の単量体以外にも、結着性等の性能をさらに向上させるために、その他の単量体として（メタ）アクリロニトリル等のニトリル基含有単量体、（メタ）アクリル酸、イタンコン酸、マレイン酸等のカルボキシル基含有単量体を共重合単量体として用いてもよい。
　上記共重合体中における上記その他の単量体に由来する構造単位は、例えば、０～３０質量％の範囲とすることができ、また例えば、０～２０質量％の範囲とすることができる。 In addition to the above-mentioned monomers, the styrene / butadiene latex is a monomer containing a nitrile group such as (meth) acrylonitrile, ) A carboxyl group-containing monomer such as acrylic acid, itaconic acid and maleic acid may be used as a copolymerization monomer.
The structural unit derived from the other monomer in the copolymer can be, for example, in the range of 0 to 30% by mass, and can be in the range of 0 to 20% by mass, for example.
　本開示の二次電池電極合剤層用組成物は、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カルボキシル基含有重合体粒子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。電極合剤層用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。また、上記スラリーの粘度は、６０ｒｐｍにおけるＢ型粘度として、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。 The composition for a secondary battery electrode mixture layer of the present disclosure contains the above active material, water, and binder as essential components, and can be obtained by mixing each component using a known means. The mixing method of each component is not particularly limited, and a known method can be adopted. However, after dry blending powder components such as carboxyl group-containing polymer particles, which are an active material, a conductive aid, and a binder, A method of mixing with a dispersion medium such as water and kneading the mixture is preferable. When the composition for an electrode mixture layer is obtained in a slurry state, it is preferable to finish the slurry without any poor dispersion or aggregation. As a mixing means, known mixers such as a planetary mixer, a thin film swirl mixer, and a self-revolving mixer can be used, but a thin film swirl mixer is used because a good dispersion state can be obtained in a short time. It is preferable to carry out. Moreover, when using a thin film swirling mixer, it is preferable to perform preliminary dispersion with a stirrer such as a disper in advance. The viscosity of the slurry can be, for example, in the range of 500 to 100,000 mPa · s as B-type viscosity at 60 rpm, and for example, in the range of 1,000 to 50,000 mPa · s. it can.
　一方、電極合剤層用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 electrode mixture layer composition is obtained in a wet powder state, it is preferably kneaded to a uniform state without unevenness in density using a Henschel mixer, blender, planetary mixer, biaxial kneader, or the like.
＜二次電池用電極＞
　本開示の二次電池用電極は、銅又はアルミニウム等の集電体表面に上記電極合剤層用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、集電体の表面に本開示の電極合剤層用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。合剤層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。 <Electrode for secondary battery>
The electrode for a secondary battery of the present disclosure includes a mixture layer formed from the above composition for an electrode mixture layer on the surface of a current collector such as copper or aluminum. The mixture layer is formed by drying and removing a medium such as water after applying the composition for an electrode mixture layer of the present disclosure to the surface of the current collector. The method for applying the mixture layer composition is not particularly limited, and a known method such as a doctor blade method, a dip method, a roll coat method, a comma coat method, a curtain coat method, a gravure coat method, and an extrusion method is adopted. be able to. Moreover, the said drying can be performed by well-known methods, such as hot air spraying, pressure reduction, (far) infrared rays, and microwave irradiation.
Usually, the mixture layer obtained after drying is subjected to a compression treatment by a die press, a roll press or the like. By compressing the active material and the binder, the strength of the mixture layer and the adhesiveness to the current collector can be improved. By compression, the thickness of the mixture layer can be adjusted to, for example, about 30 to 80% before compression, and the thickness of the mixture layer after compression is generally about 4 to 200 μm.
　本開示の二次電池用電極にセパレータ及び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。電解液は液状であってもよく、ゲル状であってもよい。
　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。 A secondary battery can be produced by providing the electrode for a secondary battery of the present disclosure with a separator and an electrolytic solution. The electrolytic solution may be liquid or gelled.
The separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of ensuring ionic conductivity by preventing a short circuit due to contact between both electrodes and holding an electrolytic solution. The separator is preferably a film-like insulating microporous film having good ion permeability and mechanical strength. As specific materials, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, and the like can be used.
　電解液は、活物質の種類に応じて一般的に使用される公知のものを用いることができる。リチウムイオン二次電池では、具体的な溶媒として、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。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。ニッケル水素二次電池では、電解液として水酸化カリウム水溶液を使用することができる。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 electrolytic solution, a known one that is generally used according to the type of the active material can be used. In the lithium ion secondary battery, as specific solvents, cyclic carbonates having high dielectric constant and high electrolyte dissolving ability such as propylene carbonate and ethylene carbonate, and low viscosity chains such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate are used. And the like, and these can be used alone or as a mixed solvent. The electrolytic solution is used by dissolving lithium salts such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , and LiAlO 4 in these solvents. In a nickel metal hydride secondary battery, an aqueous potassium hydroxide solution can be used as the electrolytic solution. A secondary battery is obtained by making a positive electrode plate and a negative electrode plate partitioned by a separator into a spiral or laminated structure and storing them 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、合剤層において電極材料との優れた結着性と集電体との優れた接着性とを示すこのため、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、車載用二次電池等に好適である。
　また、本明細書の開示によれば、二次電池電極用バインダーの製造方法並びに二次電池用電極の製造方法及び二次電池用電極も提供される。 As described above, the secondary battery electrode binder disclosed in the present specification exhibits excellent binding properties with the electrode material and excellent adhesion with the current collector in the mixture layer. Secondary batteries equipped with electrodes obtained using the above binders are able to ensure good integrity and are expected to show good durability (cycle characteristics) even after repeated charge and discharge. Suitable for batteries and the like.
Moreover, according to the indication of this specification, the manufacturing method of the binder for secondary battery electrodes, the manufacturing method of the electrode for secondary batteries, and the electrode for secondary batteries are also provided.
　以下、実施例に基づいて本開示を具体的に説明する。尚、本開示は、これらの実施例により限定されるものではない。尚、以下において「部」及び「％」は、特に断らない限り質量部及び質量％を意味する。 Hereinafter, the present disclosure will be specifically described based on examples. Note that the present disclosure is not limited to these examples. In the following, “parts” and “%” mean mass parts and mass% unless otherwise specified.
≪本重合体塩の製造≫
（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、トリメチロールプロパントリメタクリレート（共栄社化学社製、商品名「ライトエステルＴＭＰ」）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。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、重合開始点から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。また、液クロ分析により、得られた重合体は、仕込み通りの組成であることを確認した。 ≪Production of the present polymer salt≫
(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”), trimethylolpropane trimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester TMP”) 20 parts and triethylamine corresponding to 1.0 mol% with respect to the AA were charged. The reactor was sufficiently purged with nitrogen and then 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) (trade name “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) 0 as a polymerization initiator When .040 parts was added, white turbidity was observed in the reaction solution, and this point was taken as the polymerization initiation point. The monomer concentration was calculated to be 15.0%. 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. after 6 hours had elapsed from the polymerization start point. The internal temperature was maintained at 65 ° C., and cooling of the reaction liquid was started when 12 hours had elapsed from the polymerization start point. After the internal temperature dropped to 25 ° C., lithium hydroxide monohydrate (hereinafter referred to as “LiOH”). 52.5 parts) of “H 2 O”. After the addition, stirring was continued at room temperature for 12 hours 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 the medium. Moreover, it was confirmed by liquid chromatography analysis that the obtained polymer had a composition as prepared.
（架橋重合体塩Ｒ－１（Ｌｉ中和物）の膨潤前平均粒子径測定）
　上記で得られた架橋重合体塩Ｒ－１を含む重合反応液を、アセトニトリルを分散媒とするレーザー回折/散乱式粒度分布計（マイクロトラックベル社製、マイクロトラックＭＴ－３３００ＥＸII）にて粒子径測定を行った。体積基準メジアン径は０．５２μｍであった。 (Measurement of average particle diameter of crosslinked polymer salt R-1 (Li neutralized product) before swelling)
The polymerization reaction solution containing the crosslinked polymer salt R-1 obtained above was measured with a laser diffraction / scattering particle size distribution analyzer (Microtrac Bell, Microtrac MT-3300EXII) using acetonitrile as a dispersion medium. Measurements were made. The volume-based median diameter was 0.52 μm.
　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洗浄操作を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、カルボキシル基含有重合体塩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、カルボキシル基含有重合体塩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 resulting polymerization reaction liquid was centrifuged to precipitate polymer particles, and then the supernatant was removed. Then, after the sediment was redispersed in acetonitrile having the same weight as the polymerization reaction solution, the washing operation of sedimenting the polymer particles by centrifugation and removing the supernatant was repeated twice. The precipitate was collected, dried under reduced pressure at 80 ° C. for 3 hours, and volatile components were removed to obtain a carboxyl group-containing polymer salt R-1 powder. Since the crosslinked polymer salt R-1 has a hygroscopic property, it was hermetically stored in a container having a water vapor barrier property. Incidentally, IR measurement was performed on the powder of the carboxyl group-containing polymer salt R-1, and the degree of neutralization was determined from the intensity ratio of the C═O group-derived peak of the carboxylic acid and the C═O-derived peak of the carboxylic acid Li. It was 90 mol% equal to the calculated value from the preparation.
（架橋重合体塩Ｒ－１（Ｌｉ中和物）の水媒体中での平均粒子径測定）
　上記で得られた架橋重合体塩Ｒ－１の粉末０．２５ｇ、及びイオン交換水４９．７５ｇを１００ｃｃの容器に量りとり、自転／公転式攪拌機（シンキー社製、あわとり錬太郎ＡＲ－２５０）にセットした。次いで、撹拌（自転速度２０００ｒｐｍ／公転速度８００ｒｐｍ、７分）、さらに脱泡（自転速度２２００ｒｐｍ／公転速度６０ｒｐｍ、１分）処理を行い架橋重合体塩Ｒ－１（中和度９０モル％）が水に膨潤した状態のハイドロゲルを作成した。
　次に、イオン交換水を分散媒とするレーザー回折/散乱式粒度分布計（マイクロトラックベル社製、マイクロトラックＭＴ－３３００ＥＸII）にて上記ハイドロゲルの粒度分布測定を行った。ハイドロゲルに対し、過剰量の分散媒を循環しているところに、適切な散乱光強度が得られる量のハイドロゲルを投入したところ、数分後に測定される粒度分布形状が安定した。安定を確認次第、体積基準の粒度分布測定を行い、平均粒子径としてメジアン径（Ｄ５０）を求めたところ、１．７μｍであった。また、以下の基準に従い単分散性を評価した結果、（体積基準メジアン径／個数基準メジアン径）で表される粒子径分布は１．３であり、単分散性は「◎」と判断された。
評価基準；
　◎：体積基準メジアン径／個数基準メジアン径が１．５未満
　○：体積基準メジアン径／個数基準メジアン径が１．５以上、３．０未満
　△：体積基準メジアン径／個数基準メジアン径が３．０以上、１０未満
　×：体積基準メジアン径／個数基準メジアン径が１０以上 (Measurement of average particle diameter of crosslinked polymer salt R-1 (Li neutralized product) in an aqueous medium)
0.25 g of the crosslinked polymer salt R-1 powder obtained above and 49.75 g of ion-exchanged water were weighed into a 100 cc container, and a rotating / revolving stirrer (Shinky Corporation, Awatori Rentaro AR-250). ). Next, stirring (spinning speed 2000 rpm / revolving speed 800 rpm, 7 minutes) and further defoaming (spinning speed 2200 rpm / revolving speed 60 rpm, 1 minute) were performed to obtain crosslinked polymer salt R-1 (degree of neutralization 90 mol%). A hydrogel swollen in water was prepared.
Next, the particle size distribution of the hydrogel was measured with a laser diffraction / scattering particle size distribution meter (Microtrac MT-3300EXII, manufactured by Microtrac Bell) using ion-exchanged water as a dispersion medium. When an excessive amount of dispersion medium was circulated with respect to the hydrogel, an amount of the hydrogel capable of obtaining an appropriate scattered light intensity was added, and the particle size distribution shape measured after a few minutes was stabilized. As soon as the stability was confirmed, volume-based particle size distribution measurement was performed and the median diameter (D50) was determined as the average particle diameter, which was 1.7 μm. In addition, as a result of evaluating monodispersity according to the following criteria, the particle size distribution represented by (volume-based median diameter / number-based median diameter) was 1.3, and the monodispersity was determined to be “◎”. .
Evaluation criteria;
◎: Volume-based median diameter / number-based median diameter is less than 1.5 ○: Volume-based median diameter / number-based median diameter is 1.5 or more and less than 3.0 △: Volume-based median diameter / number-based median diameter is 3 0.0 or more and less than 10 ×: Volume-based median diameter / number-based median diameter of 10 or more
（製造例２～２４：架橋重合体塩Ｒ－２～Ｒ－２４の製造）
　各原料の仕込み量を表１及び表２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－２４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－２４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１６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。
　製造例１と同様の操作により、各重合体塩の膨潤前粒子径、並びに、水膨潤状態における平均粒子径及び粒子径分布を測定し、結果を表１及び表２に示した。 (Production Examples 2 to 24: Production of crosslinked polymer salts R-2 to R-24)
A polymerization reaction liquid containing crosslinked polymer salts R-2 to R-24 was obtained in the same manner as in Production Example 1, except that the amount of each raw material was as shown in Tables 1 and 2.
Subsequently, the same operation as in Production Example 1 was performed for each polymerization reaction solution, and powdered crosslinked polymer salts R-2 to R-24 were obtained. Each crosslinked polymer salt was hermetically stored in a container having a water vapor barrier property.
In Production Example 16, a crosslinked polymer Na salt (degree of neutralization 90 mol%) was obtained by using NaOH instead of LiOH.H 2 O powder.
By the same operation as in Production Example 1, the pre-swelling particle size of each polymer salt, and the average particle size and particle size distribution in the water-swollen state were measured. The results are shown in Tables 1 and 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１及び表２において用いた化合物の詳細を以下に示す。
　ＡＡ：アクリル酸
　ＤＭＡＡ：ジメチルアクリルアミド
　ＨＥＡ：ヒドロキシエチルアクリレート
　ＴＭＰＴＭＡ：トリメチロールプロパントリメタクリレート（共栄社化学社製、商品名「ライトエステルＴＭＰ」）
　ＥＤＧＭＡ：エチレングリコールジメタクリレート（冨士フィルム和光純薬社製、試薬「二メタクリル酸エチレン」）
　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（共栄社化学社製、商品名「ライトエステルＧ－２０１Ｐ」）
　ＤＰＥＰＡ：ジペンタエリスリトールペンタ及びヘキサアクリレート（東亞合成社製、商品名「アロニックスＭ－４０３」）
　ＰＥＴＡ：ペンタエリスリトールテトラアクリレート（新中村化学社製、商品名「Ａ－ＴＭＭＴ」）
　ＴＭＰＴＡ：トリメチロールプロパントリアクリレート（東亞合成社製、商品名「アロニックスＭ－３０９」）
　ＨＤＤＡ：１，６－ヘキサンジオールジアクリレート（大阪有機化学工業社製、商品名「ビスコート＃２３０」）
　ＤＶＢ：ジビニルベンゼン
　ＭＢＡＭ：メチレンビスアクリルアミド
　Ｔ－２０：トリメチロールプロパンジアリルエーテル（ダイソー社製、商品名「ネオアリルＴ－２０」）
　ＴＥＡ：トリエチルアミン
　ＴＯＡ：トリ－ｎ－オクチルアミン
　ＡｃＮ：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）（冨士フィルム和光純薬社製）
　尚、「アロニックス」は東亞合成社の登録商標である。 Details of the compounds used in Tables 1 and 2 are shown below.
AA: Acrylic acid DMAA: Dimethylacrylamide HEA: Hydroxyethyl acrylate TMPTMA: Trimethylolpropane trimethacrylate (Kyoeisha Chemical Co., Ltd., trade name “Light Ester TMP”)
EDGMA: Ethylene glycol dimethacrylate (Fuji Film Wako Pure Chemical Industries, reagent "ethylene dimethacrylate")
HAPMA: 2-hydroxy-3-acryloyloxypropyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester G-201P”)
DPEPA: Dipentaerythritol penta and hexaacrylate (trade name “Aronix M-403” manufactured by Toagosei Co., Ltd.)
PETA: Pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “A-TMMT”)
TMPTA: Trimethylolpropane triacrylate (trade name “Aronix M-309” manufactured by Toagosei Co., Ltd.)
HDDA: 1,6-hexanediol diacrylate (manufactured by Osaka Organic Chemical Industry, trade name “Biscoat # 230”)
DVB: Divinylbenzene MBAM: Methylenebisacrylamide T-20: Trimethylolpropane diallyl ether (trade name “Neoallyl T-20” manufactured by Daiso Corporation)
TEA: triethylamine TOA: tri-n-octylamine AcN: acetonitrile V-65: 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
“Aronix” is a registered trademark of Toagosei Co., Ltd.
（電極の評価）
　活物質として、負極用活物質である黒鉛、又はケイ素粒子及び黒鉛を用い、架橋重合体塩をバインダーとして用いた合剤層用組成物について、その安定性及び形成された合剤層／集電体間の剥離強度（すなわちバインダーの結着性）を測定した。黒鉛としては天然黒鉛（日本黒鉛社製、商品名「ＣＧＢ－１０」）、ケイ素粒子としては（Ｓｉｇｍａ－Ａｌｄｒｉｃｈ、Ｓｉナノパウダー、粒子径＜１００ｎｍ）を使用した。 (Evaluation of electrode)
As the active material, graphite, which is an active material for a negative electrode, or silicon particles and graphite, and the composition for a mixture layer using a crosslinked polymer salt as a binder, its stability and the formed mixture layer / current collector The peel strength between the bodies (that is, the binding property of the binder) was measured. Natural graphite (manufactured by Nippon Graphite Co., Ltd., trade name “CGB-10”) was used as graphite, and (Sigma-Aldrich, Si nanopowder, particle size <100 nm) was used as silicon particles.
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用組成物を得た。スラリー濃度（固形分）は、３９．２％と算出された。 Example 1
After weighing 3.2 parts of powdered crosslinked polymer Li salt R-1 into 100 parts of natural graphite and mixing well in advance, 160 parts of ion exchange water was added and predispersed with a disper, and then a thin film swirl type This dispersion was carried out for 15 seconds under the condition of a peripheral speed of 20 m / sec using a mixer (manufactured by Primics, FM-56-30) to obtain a slurry-like composition for a negative electrode mixture layer. The slurry concentration (solid content) was calculated to be 39.2%.
＜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）上に上記合剤層用組成物を塗布し、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。 <90 ° peel strength (binding property)>
Using a variable applicator, the mixture layer composition is applied onto a 20 μm thick copper foil (manufactured by Nippon Foil Co., Ltd.) and dried in an air dryer at 100 ° C. for 15 minutes. A layer was formed. Thereafter, the mixture layer was rolled to have a thickness of 70 ± 5 μm and a packing density of 1.70 ± 0.20 g / cm 3 to prepare a negative electrode.
　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１６．０Ｎ／ｍと高く、良好であった。 After the negative electrode obtained above was cut into a strip having a width of 25 mm, the mixture layer surface of the sample was attached to a double-sided tape fixed on a horizontal surface to prepare a sample for a peel test. After the test sample was dried at 60 ° C. under reduced pressure overnight, 90 ° peeling at a tensile speed of 50 mm / min was performed, and the peel strength between the mixture layer and the copper foil was measured. The peel strength was as good as 16.0 N / m.
実施例２～２４、及び比較例１～２
　活物質及びバインダーとして使用するカルボキシル基含有重合体塩を表３～表５の通り用いた以外は実施例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。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９０°剥離強度を評価し、結果を表３～表５に示した。 Examples 2 to 24 and Comparative Examples 1 and 2
A mixture layer composition was prepared by the same operation as in Example 1 except that the carboxyl group-containing polymer salt used as the active material and the binder was used as shown in Tables 3 to 5. In Example 3 and Example 4, natural graphite and silicon particles were stirred for 1 hour at 400 rpm using a planetary ball mill (manufactured by FRITSCH, P-5), and the resulting mixture was powdered cross-linked polymer. After weighing 3.2 parts of Li salt R-2 and mixing well in advance, a mixture layer composition was prepared by performing the same operation as in Example 1. The 90 ° peel strength of each mixture layer composition was evaluated, and the results are shown in Tables 3 to 5.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　各実施例は、本開示に属する二次電池電極用バインダーを含む電極合剤層組成物及びこれを用いて電極を作製したものである。各合剤層組成物から得られた電極の合剤層と集電体との剥離強度はいずれも高い値が得られており、優れた結着性を示すものであった。
　一方、架橋性単量体を使用していない重合体塩による比較例１、及びアリル基以外の重合性不飽和基を持たない架橋性単量体による架橋重合体塩を用いた比較例２の剥離強度は、実施例に比較すると低い値であった。 In each example, an electrode mixture layer composition containing a binder for a secondary battery electrode belonging to the present disclosure and an electrode produced using the electrode mixture layer composition. The peel strength between the electrode mixture layer and the current collector of the electrode obtained from each mixture layer composition had a high value, and exhibited excellent binding properties.
On the other hand, Comparative Example 1 using a polymer salt not using a crosslinkable monomer and Comparative Example 2 using a crosslinkable polymer salt using a crosslinkable monomer having no polymerizable unsaturated group other than an allyl group. The peel strength was a low value compared to the examples.
　本開示の二次電池電極用バインダーは、合剤層において優れた結着性を示すこのため、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、良好な耐久性（サイクル特性）を示すと予想され、車載用二次電池への適用が期待される。また、シリコンを含む活物質の使用にも有用であり、電池の高容量化への寄与が期待される。
　本開示の二次電池電極用バインダーは、特に非水電解質二次電池電極に好適に用いることができ、中でも、エネルギー密度が高い非水電解質リチウムイオン二次電池に有用である。 Because the secondary battery electrode binder of the present disclosure exhibits excellent binding properties in the mixture layer, the secondary battery including the electrode obtained using the binder has good durability (cycle characteristics). ) And is expected to be applied to in-vehicle secondary batteries. It is also useful for the use of active materials containing silicon, and is expected to contribute to higher battery capacity.
The binder for a secondary battery electrode of the present disclosure can be suitably used particularly for a nonaqueous electrolyte secondary battery electrode, and is particularly useful for a nonaqueous electrolyte lithium ion secondary battery having a high energy density.

Claims (8)

  1. 　架橋重合体を含有する二次電池電極用バインダーであって、
    　前記架橋重合体は、非架橋性単量体及び架橋性単量体を含む単量体組成物を重合して得られ、
    　前記非架橋性単量体は、該非架橋性単量体の総量に対し、エチレン性不飽和カルボン酸単量体を５０質量％以上１００質量％以下含み、
    　前記架橋性単量体は、アリル基以外の重合性不飽和基を少なくとも１個有する単量体を含み、
    　前記架橋重合体は、中和度８０～１００モル％に中和された後、水媒体中で測定した粒子径が、体積基準メジアン径で０．１μｍ以上、１０μｍ以下である、二次電池電極用バインダー。     A secondary battery electrode binder containing a crosslinked polymer,
    The crosslinked polymer is obtained by polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer,
    The non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer,
    The crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group,
    The crosslinked polymer is neutralized to a neutralization degree of 80 to 100 mol%, and then has a particle diameter measured in an aqueous medium of 0.1 μm or more and 10 μm or less in terms of volume-based median diameter. Binder.
  2. 　前記架橋性単量体の使用量は、前記非架橋性単量体の総量１００質量部に対し、０．１質量部以上、１０質量部以下である請求項１に記載の非水電解質二次電池電極用バインダー。 2. The nonaqueous electrolyte secondary according to claim 1, wherein the amount of the crosslinkable monomer used is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total amount of the noncrosslinkable monomer. Battery electrode binder.
  3. 　前記架橋性単量体は、（メタ）アクリロイル基、（メタ）アクリロイルオキシ基、（メタ）アクリルアミド基及びスチリル基からなる群より選ばれる１種以上の重合性不飽和基を有する請求項１又は２に記載の二次電池電極用バインダー。 The said crosslinkable monomer has 1 or more types of polymerizable unsaturated groups chosen from the group which consists of a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acrylamide group, and a styryl group. The binder for secondary battery electrodes as described in 2.
  4. 　前記架橋重合体は、該架橋重合体が有するカルボキシル基の５０モル％以上が中和された塩である請求項１～３のいずれか１項に記載の二次電池電極用バインダー。 The binder for a secondary battery electrode according to any one of claims 1 to 3, wherein the crosslinked polymer is a salt in which 50 mol% or more of carboxyl groups of the crosslinked polymer are neutralized.
  5. 　二次電池電極用バインダーに用いられる架橋重合体又はその塩の製造方法であって、
    　沈殿重合法により、非架橋性単量体及び架橋性単量体を含む単量体組成物を重合する重合工程を備え、
    　前記非架橋性単量体は、該非架橋性単量体の総量に対し、エチレン性不飽和カルボン酸単量体を５０質量％以上１００質量％以下含み、
    　前記架橋性単量体は、アリル基以外の重合性不飽和基を少なくとも１個有する単量体を含み、
    　前記架橋重合体は、中和度８０～１００モル％に中和された後、水媒体中で測定した粒子径が、体積基準メジアン径で０．１μｍ以上、１０μｍ以下である、方法。     A method for producing a crosslinked polymer or a salt thereof used as a binder for a secondary battery electrode,
    A polymerization step of polymerizing a monomer composition containing a non-crosslinkable monomer and a crosslinkable monomer by precipitation polymerization;
    The non-crosslinkable monomer contains 50% by mass or more and 100% by mass or less of an ethylenically unsaturated carboxylic acid monomer with respect to the total amount of the non-crosslinkable monomer,
    The crosslinkable monomer includes a monomer having at least one polymerizable unsaturated group other than an allyl group,
    A method in which the crosslinked polymer is neutralized to a degree of neutralization of 80 to 100 mol%, and the particle diameter measured in an aqueous medium is 0.1 μm or more and 10 μm or less in terms of volume-based median diameter.
  6. 　請求項１～４のいずれか１項に記載のバインダー、活物質及び水を含む二次電池電極合剤層用組成物。 A composition for a secondary battery electrode mixture layer comprising the binder according to any one of claims 1 to 4, an active material, and water.
  7. 　負極活物質として炭素系材料またはケイ素系材料を含む請求項６に記載の二次電池電極合剤層用組成物。 The composition for a secondary battery electrode mixture layer according to claim 6, comprising a carbon-based material or a silicon-based material as the negative electrode active material.
  8. 　集電体表面に、請求項６又は７に記載の二次電池電極合剤層用組成物から形成される合剤層を備えた二次電池電極。 The secondary battery electrode provided with the mixture layer formed from the composition for secondary battery electrode mixture layers of Claim 6 or 7 on the collector surface.
PCT/JP2019/021079 2018-05-30 2019-05-28 Binder for secondary battery electrode and use thereof WO2019230714A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2020522208A JP7226442B2 (en) 2018-05-30 2019-05-28 Binder for secondary battery electrode and its use

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018-102905 2018-05-30
JP2018102905 2018-05-30

Publications (1)

Publication Number Publication Date
WO2019230714A1 true WO2019230714A1 (en) 2019-12-05

Family

ID=68698847

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/021079 WO2019230714A1 (en) 2018-05-30 2019-05-28 Binder for secondary battery electrode and use thereof

Country Status (2)

Country Link
JP (1) JP7226442B2 (en)
WO (1) WO2019230714A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021241404A1 (en) * 2020-05-26 2021-12-02 東亞合成株式会社 Non-aqueous electrolyte secondary battery electrode binder and use therefor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017073589A1 (en) * 2015-10-30 2017-05-04 東亞合成株式会社 Binder for nonaqueous electrolyte secondary cell electrode, method for producing binder, and use thereof

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017073589A1 (en) * 2015-10-30 2017-05-04 東亞合成株式会社 Binder for nonaqueous electrolyte secondary cell electrode, method for producing binder, and use thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021241404A1 (en) * 2020-05-26 2021-12-02 東亞合成株式会社 Non-aqueous electrolyte secondary battery electrode binder and use therefor

Also Published As

Publication number Publication date
JPWO2019230714A1 (en) 2021-07-08
JP7226442B2 (en) 2023-02-21

Similar Documents

Publication Publication Date Title
JP6150031B1 (en) Nonaqueous electrolyte secondary battery electrode binder, method for producing the same, and use thereof
JP6465323B2 (en) Nonaqueous electrolyte secondary battery electrode binder and use thereof
JP6729603B2 (en) Binder for non-aqueous electrolyte secondary battery electrode, method for producing the same, and use thereof
JP6638747B2 (en) Binder for secondary battery electrode and its use
JP6354929B1 (en) Nonaqueous electrolyte secondary battery electrode binder and use thereof
JP6388145B2 (en) Nonaqueous electrolyte secondary battery electrode mixture layer composition, method for producing the same, and use thereof
JPWO2016158939A1 (en) Nonaqueous electrolyte secondary battery electrode mixture layer composition, method for producing the same, and use thereof
WO2018180812A1 (en) Method for manufacturing crosslinked polymer or salt thereof
WO2021070738A1 (en) Secondary battery electrode binder, secondary battery electrode mixture layer composition, secondary battery electrode, and secondary battery
JP7372602B2 (en) Binder for secondary battery electrodes and its use
WO2020110847A1 (en) Binder for secondary battery electrode, composition for secondary battery electrode mixture layer, and secondary battery electrode
JP7234934B2 (en) Binder for secondary battery electrode and its use
JP6988888B2 (en) Binder for non-aqueous electrolyte secondary battery electrode, its manufacturing method, and its application
JP7160222B2 (en) Method for producing binder for non-aqueous electrolyte secondary battery electrode
JP7226442B2 (en) Binder for secondary battery electrode and its use
WO2018180232A1 (en) Binder for non-aqueous electrolyte secondary cell electrode
WO2020218049A1 (en) Secondary battery electrode binder and use therefor
JP7322882B2 (en) Binder for secondary battery electrode and its use
JPWO2019017315A1 (en) Binder for non-aqueous electrolyte secondary battery electrode and use thereof
JP7211418B2 (en) Binder for secondary battery electrode and its use
JPWO2020090695A1 (en) Binder for secondary battery electrode and its use
WO2019225705A1 (en) Composition for secondary battery electrode mixture layer, and secondary battery electrode

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19811081

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2020522208

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19811081

Country of ref document: EP

Kind code of ref document: A1