WO2019017317A1 - Binder for non-aqueous electrolyte secondary battery electrode and use of same - Google Patents

Binder for non-aqueous electrolyte secondary battery electrode and use of same Download PDF

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Publication number
WO2019017317A1
WO2019017317A1 PCT/JP2018/026659 JP2018026659W WO2019017317A1 WO 2019017317 A1 WO2019017317 A1 WO 2019017317A1 JP 2018026659 W JP2018026659 W JP 2018026659W WO 2019017317 A1 WO2019017317 A1 WO 2019017317A1
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Prior art keywords
mass
binder
secondary battery
electrolyte secondary
crosslinked polymer
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PCT/JP2018/026659
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French (fr)
Japanese (ja)
Inventor
朋子 仲野
直彦 斎藤
剛史 長谷川
松崎　英男
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東亞合成株式会社
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Priority to JP2019531025A priority Critical patent/JP7078048B2/en
Publication of WO2019017317A1 publication Critical patent/WO2019017317A1/en
Priority to JP2022080181A priority patent/JP7160222B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of 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
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—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 invention relates to a binder for non-aqueous electrolyte secondary battery electrodes that can be used for lithium ion secondary batteries and the like, applications thereof, and a method for producing a carboxyl group-containing crosslinked polymer or a salt thereof used for the binder.
  • non-aqueous electrolyte secondary battery for example, a lithium ion secondary battery is well known.
  • the non-aqueous electrolyte secondary battery electrode is produced by applying and drying a composition for forming an electrode mixture layer containing an active material, a binder and the like on a current collector.
  • a binder used for the negative electrode mixture layer composition an aqueous binder containing styrene butadiene rubber (SBR) latex and carboxymethyl cellulose (CMC) is used.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • the binder containing acrylic acid type polymer aqueous solution or aqueous dispersion is known as a binder which is excellent in dispersibility and binding property.
  • NMP N-methyl-2-pyrrolidone
  • PVDF polyvinylidene fluoride
  • Patent Document 1 discloses a binder containing a crosslinked polymer (salt) having an ethylenic unsaturated carboxylic acid monomer as a constituent monomer and having a specific aqueous dispersion viscosity at a degree of neutralization of 90 mol%.
  • Patent Document 2 discloses a binder which is a crosslinked polymer having a carboxyl group or a salt thereof, and which has a sufficiently small particle size when dispersed in brine after neutralization.
  • the binders disclosed in Patent Documents 1 and 2 both have excellent binding properties, but with the improvement of the performance of lithium ion secondary batteries, there is an increasing demand for binders having higher binding power.
  • it is effective to increase the molecular weight of the polymer to be a binder.
  • it is known that it is effective to carry out a polymerization reaction under conditions of high monomer concentration.
  • the polymer obtained is excellent in dispersion stability, and in the electrode composition, those which exist as polymer particles of small particles without being united are more excellent in uniform dispersion in the electrode mixture layer.
  • the adhesion point with the active material and the like increases, it is considered preferable also from the viewpoint of improving the binding property.
  • polymerizing by the high monomer concentration which exceeds 20 mass% is disclosed in the Example as for the binder of patent document 1, room for the further improvement in binding property is disclosed. was there. It is presumed that the particle size of the crosslinked polymer is not sufficiently small.
  • the binder described in Patent Document 2 also exhibits excellent binding properties, the monomer concentration at the time of polymerization of each crosslinked polymer disclosed in the examples is about 10 mass% or so is there.
  • the present disclosure also provides a composition for a non-aqueous electrolyte secondary battery electrode mixture layer obtained using the binder and a non-aqueous electrolyte secondary battery electrode.
  • the present inventors have intensively studied to solve the above problems, and as a result, a crosslinked polymer obtained by polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer in the presence of an organic amine compound or The binder containing the salt was well bound to the electrode active material and the like, and it was found that the electrode mixture layer containing the binder exhibits excellent binding properties.
  • the present invention has been completed based on these findings.
  • a binder for a non-aqueous electrolyte secondary battery electrode containing a crosslinked polymer or a salt thereof The non-aqueous electrolyte secondary battery, wherein the crosslinked polymer comprises a structural unit derived from an ethylenically unsaturated carboxylic acid monomer, and is obtained by polymerizing a monomer component in the presence of an organic amine compound. Binder for electrodes.
  • the organic amine compound has a value (C / N) represented by a ratio of the number of carbon atoms to the number of nitrogen atoms present in the organic amine compound of 3 or more. Binder for secondary battery electrodes.
  • a method for producing a crosslinked polymer or a salt thereof used as a binder for a non-aqueous electrolyte secondary battery electrode A method comprising a polymerization step of polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer by a precipitation polymerization method in the presence of an organic amine compound.
  • a composition for a non-aqueous electrolyte secondary battery electrode mixture layer comprising the binder according to any one of the above [1] to [4], an active material and water.
  • a non-aqueous electrolyte secondary battery electrode comprising a mixture layer formed of the composition for a non-aqueous electrolyte secondary battery electrode mixture layer according to the above [6] or [7] on the surface of a current collector .
  • the binder for a non-aqueous electrolyte secondary battery electrode of the present invention exhibits excellent binding to electrode active materials and the like. Moreover, the said binder can exhibit favorable adhesiveness also with a collector. For this reason, while being excellent in binding property, the electrode mixture layer containing the said binder and the electrode provided with this can maintain the integrity. For this reason, it is possible to suppress deterioration of the electrode mixture layer due to volume change and shape change of the active material accompanying charge and discharge, and it is possible to obtain a secondary battery with high durability (cycle characteristics).
  • the composition for a non-aqueous electrolyte secondary battery electrode mixture layer of the present invention has a good binding property to the electrode material and a good adhesion to the current collector, the electrode mixture layer having a good integrity can be obtained. It is possible to form a non-aqueous electrolyte secondary battery electrode with good electrode characteristics.
  • the binder for a non-aqueous electrolyte secondary battery electrode of the present invention contains a crosslinked polymer or a salt thereof, and can be made into an electrode mixture layer composition by mixing with an active material and water.
  • the composition described above may be in the form of a slurry capable of being coated on the current collector, or may be prepared as a wet powder to be able to cope with pressing on the surface of the current collector.
  • the non-aqueous electrolyte secondary battery electrode of the present invention can be obtained by forming a mixture layer formed of the above composition on the surface of a current collector such as a copper foil or an aluminum foil.
  • (meth) acrylic means acrylic and / or methacrylic
  • (meth) acrylate means acrylate and / or methacrylate
  • (meth) acryloyl group means an acryloyl group and / or a methacryloyl group.
  • the binder of the present invention comprises a crosslinked polymer having a carboxyl group or a salt thereof.
  • the crosslinked polymer having a carboxyl group or a salt thereof may have a structural unit derived from an ethylenically unsaturated carboxylic acid.
  • the crosslinked polymer can have a structural unit derived from an ethylenically unsaturated carboxylic acid monomer (hereinafter, also referred to as "component (a)").
  • component (a) ethylenically unsaturated carboxylic acid monomer
  • the component (a) can be introduced into a crosslinked polymer, for example, by polymerizing a monomer containing an ethylenically unsaturated carboxylic acid monomer. In addition, it can also be obtained by (co) polymerizing a (meth) acrylic acid ester monomer and then hydrolyzing it. In addition, after (meth) acrylamide and (meth) acrylonitrile are polymerized, they may be treated with a strong alkali, or a method of reacting an acid anhydride with a polymer having a hydroxyl group may be used.
  • Ethylenically unsaturated carboxylic acid monomers include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamidoalkyls such as (meth) acrylamidohexanoic acid and (meth) acrylamidododecanoic acid Carboxylic acid; ethylenically unsaturated monomers having a carboxyl group such as monohydroxyethyl (meth) acrylate, ⁇ -carboxy-caprolactone mono (meth) acrylate, ⁇ -carboxyethyl (meth) acrylate, etc. And the like.
  • Alkali neutralized products may be mentioned, and one of them may be used alone, or two or more may be used in combination.
  • a polymer having a long primary chain length is obtained because the polymerization rate is large, and a compound having an acryloyl group as a polymerizable functional group is preferable, and acrylic acid is particularly preferable in that the binding ability of the binder is good. is there.
  • acrylic acid is used as the ethylenically unsaturated carboxylic acid monomer, a polymer having a high carboxyl group content can be obtained.
  • content of (a) component in a crosslinked polymer is not specifically limited, For example, 10 mass% or more and 100 mass% or less can be contained with respect to the total structural unit of a crosslinked polymer.
  • the lower limit is, for example, 20% by mass or more, for example, 30% by mass or more, and for example, 40% by mass or more.
  • the lower limit may be 50% by mass or more, for example, 60% by mass or more, for example 70% by mass or more, and for example 80% by mass or more.
  • the upper limit is, for example, 99% by mass or less, for example, 98% by mass or less, and for example, 95% by mass or less, and for example, 90% by mass or less.
  • the range may be a combination of such lower limit and upper limit as appropriate, and is, for example, 10% by mass or more and 100% by mass or less, and for example, 20% by mass or more and 100% by mass or less It is 30 mass% or more and 100 mass% or less, and can be, for example, 50 mass% or more and 99 mass% or less.
  • the crosslinked polymer of the present invention contains, in addition to the component (a), a structural unit derived from another ethylenically unsaturated monomer copolymerizable therewith (hereinafter, also referred to as "component (b)"). be able to.
  • component (b) for example, 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 etc.
  • component (b) for example, 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 etc.
  • component (b) for example, an ethylenically unsaturated monomer compound having an anionic group other than a
  • These structural units are 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 monomer containing a nonionic ethylenically unsaturated monomer Can be introduced by copolymerization.
  • a structural unit derived from a nonionic ethylenic unsaturated monomer is preferable from the viewpoint that an electrode with good flexibility is obtained, and the binding property of the binder is excellent.
  • (meth) acrylamide and derivatives thereof are preferable.
  • a structural unit derived from a hydrophobic ethylenic unsaturated monomer having a solubility in water of 1 g / 100 ml or less is introduced as the component (b), a strong interaction with the electrode material can be exhibited, Good binding can be exhibited for the active material. This is preferable because it is possible to obtain a firm and integral electrode mixture layer.
  • a structural unit derived from an alicyclic structure-containing ethylenic unsaturated monomer is particularly preferred.
  • the proportion of the component (b) can be 0% by mass or more and 90% by mass or less with respect to the total structural units of the crosslinked polymer.
  • 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, and 5% by mass or more and 40% by mass or less 10 mass% or more and 30 mass% or less may be sufficient.
  • the component (b) is contained in an amount of 1% by mass or more based on the total structural units of the crosslinked polymer, the affinity to the electrolytic solution is improved, and therefore, the effect of improving lithium ion conductivity can also be expected.
  • Examples of (meth) acrylamide derivatives include N-alkyl (eg, isopropyl (meth) acrylamide, t-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, etc.) Meta) acrylamide compounds; N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide, etc. may be mentioned, and one of them may be used alone, or two You may use combining the above.
  • N-alkyl eg, isopropyl (meth) acrylamide, t-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, etc.
  • Meta acrylamide compounds
  • N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acryl
  • Examples of the alicyclic structure-containing ethylenic unsaturated monomer include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth ) (Meth) acrylic acid cycloalkyl ester which may have an aliphatic substituent such as cyclodecyl acrylate and (meth) acrylic acid cyclododecyl; isobornyl (meth) acrylate; adamantyl (meth) acrylate; ) Dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and cyclohexane dimethanol mono (meth) acrylate and cyclodecane di methanol mono (meth) acryl
  • (meth) acrylic acid ester As another nonionic ethylenically unsaturated monomer, you may use (meth) acrylic acid ester, for example.
  • (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate and 2-ethylhexyl (meth) acrylate Meta) acrylic acid alkyl ester compounds;
  • (Meth) acrylic acid aralkyl ester compounds such as phenyl (meth) acrylate, phenylmethyl (meth) acrylate and phenylethyl (meth) acrylate;
  • (Meth) acrylic acid alkoxy alkyl ester compounds such as 2-methoxyethyl (meth) acrylic acid and ethoxyethyl (meth) acrylic acid;
  • (Meth) acrylic acid hydroxyalkyl ester compounds such as hydroxye
  • compounds having an ether bond such as (meth) acrylate alkoxyalkyls such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, are preferable and 2-methoxyethyl (meth) acrylate are more preferable.
  • nonionic ethylenically unsaturated monomers a compound having an acryloyl group is preferable in that a polymer having a long primary chain length can be obtained because the polymerization rate is fast and the binding ability of the binder is good.
  • the compound whose glass transition temperature (Tg) of a homopolymer is 0 degrees C or less at the point which the bending resistance of the electrode obtained becomes favorable is preferable.
  • the crosslinked polymer may be a salt.
  • Types of salts are not particularly limited, but alkali metal salts such as lithium, sodium and potassium; alkaline earth metal salts such as calcium salts and barium salts; other metal salts such as magnesium salts and aluminum salts; ammonium salts and organic An amine salt etc. are mentioned.
  • alkali metal salts and magnesium salts are preferable, and alkali metal salts are more preferable, from the viewpoint that an adverse effect on battery characteristics hardly occurs.
  • the crosslinking method in the crosslinked polymer of the present invention is not particularly limited, and an embodiment by the following method is exemplified. 1) Copolymerization of a crosslinkable monomer 2) Use of chain transfer to polymer chain during radical polymerization 3) After synthesis of a polymer having a reactive functional group, a crosslinker is added if necessary and post-crosslinking Among the above, the method by the copolymerization of a crosslinkable monomer is preferable in that the operation is simple and the degree of crosslinking can be easily controlled.
  • Crosslinkable monomer a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups, a monomer having a crosslinkable functional group capable of self-crosslinking such as a hydrolyzable silyl group, etc. It can be mentioned.
  • the above-mentioned polyfunctional polymerizable monomer is a compound having two or more polymerizable functional groups such as (meth) acryloyl group and alkenyl group in the molecule, and a polyfunctional (meth) acrylate compound, a polyfunctional alkenyl compound, Examples thereof include compounds having both an acryloyl group and an alkenyl group.
  • polyfunctional alkenyl compounds are preferable in that a uniform crosslinked structure can be easily obtained, and polyfunctional allyl ether compounds having a plurality of allyl ether groups in the molecule are particularly preferable.
  • polyfunctional (meth) acrylate compounds include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol Di) (meth) acrylates of dihydric alcohols such as meta) acrylate; trimethylolpropane tri (meth) acrylate, tri (meth) acrylate of trimethylol propane ethylene oxide modified product, glycerin tri (meth) acrylate, pentaerythritol tri ( Poly (meth) acrylates such as tri (meth) acrylates and tetra (meth) acrylates of trivalent or higher polyhydric alcohols such as meth) acrylates and pentaerythritol tetra (meth) acrylates Relate; methylenebisacrylamide, it can be mentioned bisamides such as hydroxyethylene bis(
  • polyfunctional alkenyl compounds polyfunctional allyl ether compounds such as trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, polyallyl saccharose; diallyl phthalate and the like
  • polyfunctional vinyl compounds such as divinylbenzene.
  • Examples of compounds having both (meth) acryloyl group and alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl and the like can be mentioned.
  • the monomer having a crosslinkable functional group that is self-crosslinkable include hydrolyzable silyl group-containing vinyl monomers, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate, etc. Can be mentioned. These compounds can be used singly or in combination of two or more.
  • the hydrolyzable silyl group-containing vinyl monomer is not particularly limited as long as it is a vinyl monomer having at least one hydrolyzable silyl group.
  • vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, etc .
  • silyl such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylate and the like
  • Silyl group-containing methacrylic acid esters such as trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilyl propyl methacrylate; trimethoxysilylpropyl vinyl ether etc.
  • silyl group-containing vinyl esters such as vinyl
  • the amount of the crosslinking monomer used is the total amount of monomers (non-crosslinking monomers) other than the crosslinking monomer.
  • the amount is preferably 0.02 to 0.7 mol%, more preferably 0.03 to 0.4 mol%. If the amount of use of the crosslinkable monomer is 0.02 mol% or more, it is preferable in that the binding property and the stability of the mixture layer slurry become better. If it is 0.7 mol% or less, the stability of the crosslinked polymer tends to be high.
  • the particle size of the crosslinked polymer is not particularly limited. However, in the mixture layer composition, water having an appropriate particle size without the crosslinked polymer being present as a large particle size block (secondary aggregate) When it is well dispersed as swollen particles, a binder containing the crosslinked polymer is preferable because it can exhibit good binding performance.
  • the particle size of the crosslinked polymer of the present invention or the salt thereof when dispersed in water having a degree of neutralization of 80 to 100 mol% based on the carboxyl group of the crosslinked polymer water swelled particle size Is preferably in the range of 0.1 ⁇ m or more and 10 ⁇ m or less in terms of volume-based median diameter.
  • a more preferable range of the particle diameter is 0.2 ⁇ m or more and 5.0 ⁇ m or less, and a further preferable range is 0.5 ⁇ m or more and 3.0 ⁇ m or less.
  • the particle size is in the range of 0.1 ⁇ m or more and 10 ⁇ m or less, the particle size is uniform and suitable in the mixture layer composition, so the stability of the mixture layer composition is high and the binding property is excellent. It is possible to demonstrate If the particle size is 10 ⁇ m or less, sufficient binding properties can be exhibited. If the particle size is 0.1 ⁇ m or more, a crosslinked polymer can be stably produced. In addition, the said water swelling particle diameter can be measured by the method as described in an Example of this specification.
  • the cross-linked polymer is unneutralized or less than 80 mol% neutralization degree, neutralize to 80 to 100 mol% neutralization degree with alkali metal hydroxide etc. and measure the particle size when dispersed in water do it.
  • the crosslinked polymer or a salt thereof often exists as a lumped particle in which primary particles are associated and aggregated.
  • the particle size in the above water dispersion is in the above range, the cross-linked polymer or the salt thereof has extremely excellent dispersibility, and it is neutralized to a neutralization degree of 80 to 100 mol% to be water.
  • dispersing lumped particles are loosened, and even if it is a dispersion of primary particles or a secondary aggregate, a stable dispersion state is formed with the particle diameter in the range of 0.1 to 10 ⁇ m. is there.
  • the particle size distribution which is a value obtained by dividing the volume average median size of the water-swelled particle size by the number average median size, is preferably 10 or less, more preferably 3.0 or less, further preferably from the viewpoint of binding properties. Is 1.5 or less.
  • the lower limit of the particle size distribution is usually 1.0.
  • the particle size (dry particle size) of the crosslinked polymer of the present invention or a salt thereof at the time of drying is preferably in the range of 0.03 ⁇ m or more and 3 ⁇ m or less on a volume basis 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 said dry particle diameter can be measured by the method as described in this-application Example.
  • the toughness increases, and it becomes possible to obtain high bondability, and the viscosity of the aqueous dispersion increases.
  • a crosslinked polymer (salt) obtained by applying a relatively small amount of crosslinking to a polymer having a long primary chain length exists in water as a water-swollen microgel body.
  • the thickening effect and the dispersion stabilizing effect are exhibited by the interaction of the microgel body.
  • the interaction of the microgel body changes depending on the degree of water swelling of the microgel body and the strength of the microgel body, but these are influenced by the degree of crosslinking of the crosslinked polymer.
  • the degree of crosslinking is too low, the strength of the microgel may be insufficient, and the dispersion stabilization effect and the binding property may be insufficient.
  • the degree of crosslinking is too high, the degree of swelling of the microgel may be insufficient, and the dispersion stabilizing effect and the binding property may be insufficient. That is, it is desirable that the crosslinked polymer be a finely crosslinked polymer obtained by appropriately crosslinking the polymer having a sufficiently long primary chain length.
  • acid groups such as carboxyl groups derived from ethylenically unsaturated carboxylic acid monomers are neutralized so that the degree of neutralization in the mixture layer composition is 20 to 100 mol%. And is preferably used as a salt embodiment.
  • the degree of neutralization is more preferably 50 to 100 mol%, and still more preferably 60 to 95 mol%. When the degree of neutralization is 20 mol% or more, it is preferable in that the water swellability is good and the dispersion stabilizing effect is easily obtained.
  • the above-mentioned degree of neutralization can be calculated by calculation from charged values of a monomer having an acid group such as a carboxyl group and a neutralizing agent used for neutralization.
  • the cross-linked polymer may be a known polymerization method such as solution polymerization, precipitation polymerization, suspension polymerization or emulsion polymerization, but precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) in terms of productivity Is preferred.
  • Heterogeneous polymerization methods such as precipitation polymerization, suspension polymerization, and emulsion polymerization are preferable, and precipitation polymerization is more preferable, from the viewpoint of obtaining better performance with regard to binding properties and the like.
  • Precipitation polymerization is a method of producing a polymer by carrying out a polymerization reaction in a solvent which dissolves the raw material unsaturated monomer but does not substantially dissolve the produced polymer.
  • the polymer particles become larger due to aggregation and growth, and a dispersion liquid of polymer particles in which primary particles of several tens of nm to several hundreds of nm are secondarily aggregated to several ⁇ m to several tens of ⁇ m is obtained.
  • Dispersion stabilizers can also be used to control the particle size of the polymer.
  • the above secondary aggregation can also 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.
  • the polymerization solvent a solvent selected from water, various organic solvents and the like can be used in consideration of the kind of the monomer to be used and the like. 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 1 type can be used individually or in combination of 2 or more types. Or you may use as a mixed solvent of these and water.
  • the water-soluble solvent means one having a solubility in water at 20 ° C. of more than 10 g / 100 ml.
  • a highly polar solvent preferably include water and methanol.
  • the amount of the highly polar solvent used is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and still more preferably 0.1 to 1 based on the total mass of the medium. It is .0 mass%. If the proportion of the high polar solvent is 0.05% by mass or more, the effect on the above-mentioned neutralization reaction is observed, and if it is 10.0% by mass or less, no adverse effect on the polymerization reaction is observed.
  • a highly hydrophilic ethylenic unsaturated carboxylic acid monomer such as acrylic acid
  • a highly polar solvent when added, the polymerization rate is improved, and a polymer having a long primary chain length can be easily obtained.
  • water is particularly preferable because the effect of improving the polymerization rate is large.
  • a crosslinked polymer is obtained by polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer in the presence of an organic amine compound.
  • the binder containing the crosslinked polymer or the salt thereof thus obtained can exhibit high binding properties.
  • the monomer component containing the ethylenically unsaturated carboxylic acid monomer is polymerized in the presence of the organic amine compound, the polymerization stability is improved, and the crosslinking weight is increased even at a high monomer concentration.
  • the uniting can be produced stably.
  • the monomer concentration may be, for example, about 10.0% by mass or more, but is preferably 13.0% by mass or more from the viewpoint of binding properties.
  • the monomer concentration is more preferably 15.0% by mass or more, still more preferably 17.0% by mass or more, and still more preferably 19.0% by mass or more.
  • the monomer concentration is more preferably 20.0% by mass or more, still more preferably 22.0% by mass or more, and still more preferably 25.0% by mass or more.
  • the higher the monomer concentration at the time of polymerization the higher the molecular weight can be obtained, and a polymer having a long primary chain length can be produced. Since the crosslinked polymer of the present invention is a finely crosslinked polymer obtained by appropriately crosslinking the polymer having a sufficiently long primary chain length, direct measurement of the primary chain length is analytically difficult. .
  • the primary chain length of a polymer is known to be correlated with the solution viscosity, but in the case of a crosslinked polymer, the solution viscosity also varies depending on the degree of crosslinking. Therefore, it is very difficult to define the crosslinked polymer obtained by the above method by the structure or characteristics of the polymer.
  • “monomer concentration” refers to the monomer concentration in the reaction liquid at the time of initiating polymerization.
  • the upper limit of the monomer concentration varies depending on the types of monomers and solvents used, and the polymerization method and various polymerization conditions, but if heat removal from the polymerization reaction is possible, it is approximately 40% in precipitation polymerization.
  • the degree is about 50% in suspension polymerization and about 70% in emulsion polymerization.
  • the polymerization reaction by performing the polymerization reaction in the presence of the organic amine compound, it is possible to obtain a crosslinked polymer having excellent binding properties. Furthermore, the polymerization reaction can be stably carried out even under high monomer concentration conditions, for example, exceeding 13.0% by mass. A polymer obtained by polymerization at such a high monomer concentration is excellent in binding ability because of its high molecular weight (because of the long primary chain length).
  • organic amine compound other than ammonia, for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monobutylamine, dibutylamine, tributylamine, monohexylamine, dihexylamine, trihexylamine, trioctylamine And N-alkyl substituted amines such as tridodecylamine; (alkyl) alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine and N, N-dimethylethanolamine; pyridine, piperidine, piperazine, Cyclic amines such as 1,8-bis (dimethylamino) naphthalene, morpholine and diazabicycloundecene (DBU); diethylene tri Min, N, N-dimethylbenzylamine, and the like, may be used alone or two or more of these.
  • DBU di
  • organic amine compounds other than ammonia are preferable from the viewpoint of binding ability.
  • a hydrophobic amine having a long chain alkyl group when used, larger electrostatic repulsion and steric repulsion can be obtained, so that the polymerization stability can be easily secured even when the monomer concentration is high.
  • the higher the value (C / N) represented by the ratio of the number of carbon atoms to the number of nitrogen atoms present in the organic amine compound the higher the polymerization stabilization effect by the steric repulsion effect.
  • the value of C / N is preferably 3 or more, more preferably 5 or more, further preferably 10 or more, and still more preferably 20 or more.
  • An amine compound having a high C / N value is generally a compound having a high hydrophobicity and a low amine value.
  • an amine compound having a high C / N value tends to exhibit a high polymerization stabilization effect, and it becomes possible to increase the monomer concentration at the time of polymerization, so that the polymer has a high molecular weight (primary chain And the integrity tends to be improved.
  • a crosslinked polymer having a small particle size or a salt thereof tends to be obtained. Therefore, the adhesion to the active material and the like is increased, and the binding property is improved.
  • a polymerization step of polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer For example, 10% by mass or more and 100% by mass or less of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived, and 0 mass of another ethylenically unsaturated monomer from which the component (b) is derived It is preferable to have a polymerization step of polymerizing a monomer component containing% or more and 90% by mass or less.
  • the structural unit (component (a)) derived from the ethylenically unsaturated carboxylic acid monomer is introduced into the crosslinked polymer in an amount of 10% by mass or more and 100% by mass or less through the polymerization step.
  • the use amount of the ethylenically unsaturated carboxylic acid monomer is also, for example, 20% by mass or more and 100% by mass or less, and for example, 30% by mass or more and 100% by mass or less, for example, 50% by mass Above, it is 99 mass% or less.
  • the polymerization step is preferably performed by a precipitation polymerization method in that a polymer particle having a small particle size excellent in uniformity is easily obtained.
  • an organic amine compound of 0.001 mol% or more with respect to the above-mentioned ethylenically unsaturated carboxylic acid monomer.
  • the amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, and still more preferably 0.05 mol% or more It is.
  • the amount of the organic amine compound used may be 0.3 mol% or more, or 0.5 mol% or more. Moreover, it is preferable that the upper limit of the usage-amount of an organic amine compound is 4.0 mol% or less.
  • the amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is preferably 3.0 mol% or less, more preferably 2.0 mol% or less, and still more preferably 1.0 mol% or less It is.
  • the amount of the organic amine compound used represents the molar concentration of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer, and means the degree of neutralization. Absent. That is, the valence of the organic amine compound used is not considered.
  • another ethylenically unsaturated monomer copolymerizable therewith may be contained as a monomer component.
  • the other ethylenically unsaturated monomer for example, 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, and a nonionic ethylenic character Unsaturated monomer etc. are mentioned.
  • transduce the component (b) mentioned above is mentioned.
  • the other ethylenically unsaturated monomer may be contained in an amount of 0% by mass or more and 90% by mass or less, or 1% by mass or more and 60% by mass or less based on the total amount of the monomer components.
  • the content may be 50% by mass or more, and 10% by mass or more and 30% by mass or less.
  • you may use the said crosslinkable monomer similarly.
  • polymerization initiator known polymerization initiators such as azo compounds, organic peroxides and inorganic peroxides can be used, but are not particularly limited.
  • the conditions of use can be adjusted by a known method such as heat initiation, redox initiation in combination with a reducing agent, UV initiation, etc., to obtain an appropriate radical generation amount.
  • heat initiation heat initiation
  • redox initiation in combination with a reducing agent
  • UV initiation etc.
  • 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 (also “perhexa HC"), 1,1-di (t-butylperoxy) cyclohexane (also “perhexa C”), n-butyl-4,4-di (t-butylperoxy) Barrelate (the same "perhexa V"), 2, 2- di (t- butylperoxy) butane (the same "perhexa 22"), t- butyl hydroperoxide (the same "perbutyl H”), cumene hydroperoxide (the day Oil Co., Ltd., trade name "Percumyl H”), 1,1,3,3-Tetramethylbutyl hydroperoxide (the same "Perocta H”),
  • 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, sulfur dioxide gas (SO 2 ), ferrous sulfate and the like can be used as a reducing agent.
  • the preferred amount of use of the polymerization initiator is, for example, 0.001 to 2 parts by mass, for example, 0.005 to 1 parts by mass, based on 100 parts by mass of the total amount of the monomer components to be used. For example, it is 0.01 to 0.1 parts by mass. If the amount of the polymerization initiator used is 0.001 parts by mass or more, the polymerization reaction can be stably carried out, and if it is 2 parts by mass or less, a polymer having a long primary chain length can be easily obtained.
  • the concentration of the monomer component at the time of polymerization is preferably high from the viewpoint of obtaining a polymer having a longer primary chain length.
  • the concentration of the monomer component is too high, aggregation of the polymer particles is likely to proceed, and control of the heat of polymerization is difficult, which may cause runaway of the polymerization reaction. 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.
  • the crosslinked polymer of the present invention is preferably obtained by polymerization at a monomer concentration of 13.0% by mass or more at the start of polymerization.
  • the monomer concentration is more preferably 15.0% by mass or more, further preferably 17.0% by mass or more, still more preferably 19.0% by mass or more, still more preferably 20.0% by mass It is above.
  • the monomer concentration is more preferably 22.0% by mass or more, and most preferably 25.0% by mass or more.
  • the polymerization temperature is preferably 0 to 100 ° C., and more preferably 20 to 80 ° C., although it depends on conditions such as the type and concentration of monomers to be used.
  • the polymerization temperature may be constant or may change during the polymerization reaction.
  • the polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
  • the crosslinked polymer dispersion obtained through the polymerization step can be subjected to pressure reduction and / or heat treatment or the like in the drying step to distill off the solvent, whereby the target crosslinked polymer can be obtained in the form of powder.
  • solid-liquid separation processes such as centrifugation and filtration, following a polymerization process for the purpose of removing unreacted monomer (and its salt), impurities derived from an initiator, etc. before the above-mentioned drying process. It is preferable to have a washing step using the same solvent as methanol, or the polymerization solvent.
  • the residual solvent and unreacted monomer contained in the crosslinked polymer powder are preferably as small as possible from the viewpoint of odor, battery performance and safety (cell swelling due to gasification, etc.). Specifically, it is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, more preferably 0% by mass in the crosslinked polymer powder. .1% by mass or less.
  • a polymerization reaction of a monomer composition containing an ethylenically unsaturated carboxylic acid monomer is carried out in the presence of a base compound, but an alkali compound is added to the polymer dispersion obtained by the polymerization step.
  • the solvent may be removed in the drying step.
  • an alkali compound is added when preparing the electrode mixture layer slurry to neutralize the polymer (hereinafter referred to as “after It may be called “sum”.
  • the process neutralization is preferable because secondary aggregates tend to be easily entangled.
  • the crosslinked polymer may be provided with a metal removal step of removing metal foreign matter in the state of the slurry after the polymerization step or in the state of the powder after the drying step.
  • a metal removal step of removing metal foreign matter in the state of the slurry after the polymerization step or in the state of the powder after the drying step.
  • known methods such as a lattice type magnet, a magnet strainer, a magnet filter, an electromagnetic separator, a magnet pulley, a drum magnetic separator and a suspension magnetic separator can be used.
  • the metal removing step magnetic foreign matter having a size of several tens to several hundreds of ⁇ m or more is removed.
  • the amount of foreign metal contained in the crosslinked polymer after the step of removing foreign metal is preferably 10 ppm or less, more preferably 1 ppm or less, still more preferably 0.1 ppm or less, relative to the crosslinked polymer. Is less than 0.01 ppm.
  • the composition for a non-aqueous electrolyte secondary battery electrode mixture layer of the present invention comprises a binder containing the above-described crosslinked polymer or a salt thereof, an active material, and water.
  • the use amount of the crosslinked polymer or the salt thereof in the electrode mixture layer composition of the present invention is, for example, 0.1% by mass or more and 20% by mass or less with respect to the total amount of the active material.
  • the use amount is also, 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, for example, 0.4% by mass or more and 5% by mass or less .
  • the amount of use of the crosslinked polymer and the salt thereof is less than 0.1% by mass, sufficient binding properties may not be obtained. In addition, the dispersion stability of the active material and the like may be insufficient, and the uniformity of the formed mixture layer may be reduced. On the other hand, when the use amount of the crosslinked polymer and the salt thereof exceeds 20% by mass, the electrode mixture layer composition may have a high viscosity, and the coatability to the current collector may be reduced. As a result, bumps and irregularities may be generated in the obtained mixture layer, which may adversely affect the electrode characteristics.
  • the amount of the crosslinked polymer and the salt thereof used is in the above range, a composition having excellent dispersion stability can be obtained, and a mixture layer having extremely high adhesion to the current collector can be obtained, and the result is As the battery durability improves. Furthermore, the crosslinked polymer and the salt thereof exhibit sufficiently high binding ability even in a small amount (for example, 5% by mass or less) with respect to the active material, and have a carboxy anion, so the interface resistance is small and high rate characteristics are obtained. An excellent electrode is obtained.
  • lithium salts of transition metal oxides are mainly used as the positive electrode active material, and for example, layered rock salt type and spinel type lithium containing metal oxides can be used.
  • Specific compounds of the positive electrode active material of layered rock-salt, lithium cobaltate, lithium nickelate, and, NCM ⁇ Li (Ni x, Co y, Mn z), x + y + z 1 ⁇ called ternary and NCA ⁇ Li (Ni 1-ab Co a Al b) ⁇ , and the like.
  • lithium manganate etc. are mentioned as a spinel type positive electrode active material.
  • phosphates examples include olivine-type lithium iron phosphate and the like.
  • 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 amount of unneutralized or partially neutralized crosslinked polymer used should be such that the amount of non-neutralized carboxyl groups of the crosslinked polymer is equivalent to or more than the amount of alkali eluted from the active material. Is preferred.
  • the conductive aid include carbon-based materials such as carbon black, carbon nanotubes, carbon fibers, graphite fine powder, carbon fibers, etc. Among them, carbon black, carbon nanotubes and carbon fibers from the viewpoint of easily obtaining excellent conductivity. Is preferred. Moreover, as carbon black, ketjen black and acetylene black are preferable.
  • the conductive aids may be used alone or in combination of two or more. The amount of the conductive aid can be, for example, 0.2 to 20% by mass with respect to the total amount of the active material from the viewpoint of achieving both conductivity and energy density, and for example, 0.2 to 10%. It can be mass%.
  • the positive electrode active material may be surface-coated with a conductive carbon-based material.
  • examples of the negative electrode active material include carbon-based materials, lithium metals, lithium alloys, metal oxides and the like, and one or more of these 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 materials”) are preferred, and graphite such as natural graphite and artificial graphite Hard carbon is more preferred.
  • graphite spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferable range of the particle size thereof is, for example, 1 to 20 ⁇ m, and for example, 5 to 15 ⁇ m.
  • a metal or metal oxide or the like capable of storing lithium such as silicon or tin can also be used as the negative electrode active material.
  • silicon has a higher capacity than graphite, and active materials composed of silicon materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter also referred to as “silicon-based active materials”) Can be used.
  • silicon-based active material has a high capacity, but on the other hand, there is a large volume change due to charge and discharge. For this reason, it is preferable to use together with the said carbon-type active material.
  • the compounding amount of the silicon-based active material is large, the electrode material may be broken, and the cycle characteristics (durability) may be significantly reduced.
  • the amount used is, for example, 60% by mass or less, and for example, 30% by mass or less with respect to the carbon-based active material.
  • the binder containing the crosslinked polymer of the present invention has a structural unit (component (a)) derived from the ethylenically unsaturated carboxylic acid monomer.
  • component (a) has a high affinity to the silicon-based active material and exhibits a good binding property. Therefore, since the binder of the present invention exhibits excellent binding even when using a high capacity type active material containing a silicon-based active material, it is also effective for improving the durability of the obtained electrode. It is considered to be a thing.
  • the carbon-based active material itself has good electrical conductivity, it is not always necessary to add a conductive aid.
  • a conductive auxiliary is added for the purpose of further reducing resistance, the amount used is, for example, 10% by mass or less, for example, 5% by mass or less, based on the total amount of active materials 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 with respect to the total amount of the composition. It is in the range of 65% by mass.
  • the amount of the active material used is 10% by mass or more, the migration of the binder and the like can be suppressed, and it is also advantageous in terms of the drying cost of the medium.
  • it is 75 mass% or less, the fluidity and the coatability of the composition can be secured, and a uniform mixture layer can be formed.
  • the amount of active material used is, for example, in the range of 60 to 97% by mass with respect to the total amount of the composition, and for example, 70 to 90 It is the range of mass%.
  • non-volatile components other than active materials such as binders and conductive assistants should be as small as possible within the range in which necessary binding properties and conductivity are ensured.
  • the composition for a non-aqueous electrolyte secondary battery electrode mixture layer uses water as a medium. Further, for the purpose of adjusting the properties and drying properties of the composition, lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, water soluble organic solvents such as tetrahydrofuran, N-methylpyrrolidone and the like It may be a mixed solvent with The proportion of water in the mixed medium is, for example, 50% by mass or more, and for example, 70% by mass or more.
  • the content of the medium containing water occupied in the whole composition is the coating property of the slurry, the energy cost required for drying, the viewpoint of productivity
  • the viewpoint of productivity For example, it can be in the range of 25 to 90% by mass, and can be, for example, 35 to 70% by mass.
  • the content of the above-mentioned medium can be, for example, in the range of 3 to 40% by mass from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of ⁇ 30% by mass.
  • the binder of the present invention may consist only of the above-mentioned crosslinked polymer or a salt thereof, but other than this, it is possible to use other materials such as styrene / butadiene latex (SBR), acrylic latex and polyvinylidene fluoride latex. You may use a binder component together.
  • SBR styrene / butadiene latex
  • the amount used can be, for example, 0.1 to 5% by mass or less, and for example, 0.1 to 2% by mass or less, with respect to the active material. And, for example, 0.1 to 1% by mass or less. If the amount of the other binder component used exceeds 5% by mass, the resistance may increase and the high rate characteristics may be insufficient.
  • the styrene / butadiene latex is preferable in that it is excellent in the balance between the binding property and the 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. 1 shows an aqueous dispersion.
  • aromatic vinyl monomer in addition to styrene, ⁇ -methylstyrene, vinyltoluene, divinylbenzene and the like can be mentioned, and one or more of these can be used.
  • the structural unit derived from the above-mentioned aromatic vinyl monomer in the above-mentioned copolymer can be, for example, in the range of 20 to 60% by mass, mainly from the viewpoint of binding property, and also, for example, 30 to 50 It can be in the range of mass%.
  • aliphatic conjugated diene type monomer in addition to 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene Butadiene etc. are mentioned and 1 type, or 2 or more types in 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 binding property of the binder and the flexibility of the obtained electrode are good. And, for example, in the range of 40 to 60% by mass.
  • styrene / butadiene-based latex may contain a nitrile group-containing monomer such as (meth) acrylonitrile as the other monomer in order to further improve the performance such as binding property.
  • a carboxyl group-containing monomer such as acrylic acid, itaconic acid or maleic acid may be used as a copolymer 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 also be in the range of 0 to 20% by mass, for example.
  • the composition for a non-aqueous electrolyte secondary battery electrode mixture layer of the present invention contains the above-mentioned active material, water and a binder as essential components, and is prepared by mixing the components using a known means. can get.
  • the mixing method of each component is not particularly limited, and a known method can be adopted, but after dry blending of powder components such as active material, conductive additive and crosslinked polymer particles as binder, water is used.
  • the method of mixing with a dispersion medium such as, etc., and dispersing and kneading is preferable.
  • 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 in that a good dispersion state can be obtained in a short time. Is preferred.
  • a thin film revolving mixer it is preferable to perform preliminary dispersion beforehand with a stirrer such as a disper.
  • the viscosity of the above-mentioned 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.
  • composition for the electrode mixture layer when obtained in a wet powder state, it is preferable to knead it to a uniform state without concentration unevenness using a Henschel mixer, a blender, a planetary mixer, a twin-screw kneader or the like.
  • the concentration of polyvalent metal ions in the composition for a non-aqueous electrolyte secondary battery electrode mixture layer is preferably 100 ppm or less, more preferably 50 ppm or less, more preferably 50 ppm or less, based on the crosslinked polymer. It is 10 ppm or less.
  • the polyvalent metal is not particularly limited, and examples thereof include Fe, Al, Cr, Cu, Ca and the like.
  • the electrode for a non-aqueous electrolyte secondary battery of the present invention comprises a mixture layer formed of the composition for an electrode mixture layer on the surface of a current collector such as copper or aluminum.
  • the mixture layer is formed by applying the composition for electrode mixture layer of the present invention to the surface of the current collector and then drying and removing a medium such as water.
  • 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 coating method, a comma coating method, a curtain coating method, a gravure coating method or an extrusion method is employed. be able to.
  • the said drying can be performed by well-known methods, such as a warm air blowing, 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 thickness of the mixture layer can be adjusted to, for example, about 30 to 80% before compression by compression, and the thickness of the mixture layer after compression is generally about 4 to 200 ⁇ m.
  • a non-aqueous electrolyte secondary battery can be produced by providing the electrode for a non-aqueous electrolyte secondary battery of the present invention with a separator and a non-aqueous electrolyte.
  • the separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of preventing short circuit due to the contact of both electrodes and maintaining the electrolytic solution to secure the ion conductivity.
  • the separator is preferably a film-like insulating microporous membrane having good ion permeability and mechanical strength.
  • polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene and the like can be used.
  • the non-aqueous electrolyte can be a known one commonly used in non-aqueous electrolyte secondary batteries.
  • the solvent include cyclic carbonates having a high dielectric constant such as propylene carbonate and ethylene carbonate and having a high ability to dissolve the electrolyte, and low viscosity linear carbonates such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate. These can be used alone or as a mixed solvent.
  • the non-aqueous electrolytic solution is used by dissolving a lithium salt such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , LiAlO 4 or the like in these solvents.
  • a non-aqueous electrolyte secondary battery is obtained by accommodating the positive electrode plate and the negative electrode plate separated by the separator in a spiral or laminated structure in a case or the like.
  • the binder for a non-aqueous electrolyte secondary battery electrode disclosed in the present specification exhibits excellent binding property with the electrode material and excellent adhesion property with the current collector in the mixture layer. For this reason, the non-aqueous electrolyte secondary battery provided with the electrode obtained by using the above-mentioned binder can ensure good integrity, and is expected to exhibit good durability (cycle characteristics) even if charge and discharge are repeated. And suitable for use in on-vehicle secondary batteries and the like.
  • the inside of the reactor was sufficiently purged with nitrogen, and then warmed to raise the internal temperature to 55 ° C. After confirming that the internal temperature was stabilized at 55 ° C., 2, 2′-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, trade name “V-65”) 0 as a polymerization initiator When 040 parts were added, white turbidity was observed in the reaction solution, and this point was regarded as the polymerization initiation point. The monomer concentration was calculated to be 15.0%. The polymerization reaction was continued while maintaining the internal temperature at 55 ° C. by adjusting the external temperature (water bath temperature), and the internal temperature was raised to 65 ° C. after 6 hours from the polymerization initiation point.
  • V-65 2, 2′-azobis (2,4-dimethylvaleronitrile)
  • the internal temperature is maintained at 65 ° C., and cooling of the reaction solution is started 12 hours after the reaction start point, and after the internal temperature drops to 25 ° C. lithium hydroxide monohydrate (hereinafter referred to as “LiOH” • 52.5 parts of powder of H 2 O ”) were added. After the addition, stirring was continued at room temperature for 12 hours to obtain a slurry-like polymerization reaction solution in which particles of a crosslinked polymer salt R-1 (Li salt, neutralization degree 90 mol%) were dispersed in a medium.
  • LiOH lithium hydroxide monohydrate
  • the particle size of the polymerization reaction solution containing the crosslinked polymer salt R-1 obtained above is measured using a laser diffraction / scattering type particle size distribution analyzer (Microtrac MT-3300EXII manufactured by Microtrac Bell Co., Ltd.) using acetonitrile as a dispersion medium. It measured. The volume based median diameter was 0.35 ⁇ m.
  • the resulting polymerization reaction solution was centrifuged to precipitate polymer particles, and then the supernatant was removed. Thereafter, the precipitate was re-dispersed in acetonitrile having the same weight as that of the polymerization reaction solution, and then the washing operation of settling polymer particles by centrifugation and removing the supernatant was repeated twice.
  • the precipitate was collected, dried at 80 ° C. for 3 hours under reduced pressure conditions, and volatile components were removed to obtain a powder of a crosslinked polymer salt R-1. Since the crosslinked polymer salt R-1 has hygroscopicity, it was sealed and stored in a container having water vapor barrier properties.
  • Evaluation criteria :: volume-based median diameter / number-based median diameter less than 1.5 ⁇ : volume-based median diameter / number-based median diameter 1.5 or more and less than 3.0 ⁇ : volume-based median diameter / number-based median diameter 3 .0 or more and less than 10 ⁇ : Volume based median diameter / number based median diameter is 10 or more
  • AA acrylic acid
  • IBXA isobornyl acrylate
  • DMAA N, N-dimethyl acrylamide
  • P-30 pentaerythritol triallyl ether (manufactured by Daiso, trade name "Neoallyl P-30")
  • T-20 trimethylolpropane diallyl ether (made by Daiso, trade name "Neoallyl T-20")
  • TMA trimethylamine (C / N value: 3)
  • TEA Triethylamine (C / N value: 6)
  • TOA Trioctylamine (C / N value: 24)
  • TDA tridodecylamine (C / N value: 36)
  • TSA tristearylamine (C / N value: 54)
  • Pyridine (C / N value: 5) Dibutylamine: (C / N value: 8) Hexylamine: (C / N value: 6)
  • DMAN 1,
  • Example 1 3.2 parts of powdery crosslinked polymer Li salt R-1 is weighed into 100 parts of natural graphite, mixed well in advance, 160 parts of ion exchanged water is added, predispersion is carried out with a disper, and thin film swirling type This dispersion was carried out for 15 seconds using a mixer (manufactured by Primix, FM-56-30) at a peripheral speed of 20 m / sec to obtain a slurry-like composition for a negative electrode mixture layer. The composition for the mixture layer is applied on a 20 ⁇ m thick copper foil (manufactured by Japan Foil Co., Ltd.) using a variable applicator, and the mixture is dried in a ventilation dryer at 100 ° C. for 15 minutes. A layer was formed. Thereafter, the mixture layer was rolled so as to have a thickness of 50 ⁇ 5 ⁇ m and a packing density of 1.70 ⁇ 0.20 g / cm 3 .
  • the negative electrode obtained above was cut into a strip of 25 mm width, and then the mixture layer surface of the above sample was attached to a double-sided tape fixed on a horizontal surface to prepare a sample for peeling test. After the test sample was dried at 60 ° C. under reduced pressure conditions overnight, 90 ° peeling was performed at a tensile speed of 50 mm / min, and the peel strength between the mixture layer and the copper foil was measured. The peel strength was as high as 15.2 N / m and good.
  • Examples 2 to 22 and Comparative Examples 1 to 2 A mixture layer composition was prepared by performing the same operation as in Example 1 except that the cross-linked polymer salt used as the active material and the binder was used as shown in Table 3 or Table 4.
  • the cross-linked polymer salt used as the active material and the binder was used as shown in Table 3 or Table 4.
  • natural graphite and silicon particles are stirred at 400 rpm for 1 hour using a planetary ball mill (F-5 made by FRITSCH), and a powdery crosslinked polymer is obtained in the obtained mixture.
  • 3.2 parts of Li salt R-1 was weighed, mixed well in advance, and then the same procedure as in Example 1 was carried out to prepare a mixture layer composition. The coatability and the 90 ° peel strength were evaluated for each mixture layer composition. The results are shown in Table 3 or Table 4.
  • an electrode mixture layer composition containing a binder for a non-aqueous electrolyte secondary battery electrode according to the present invention and an electrode manufactured using the same The coatability of each mixture layer composition (slurry) is good, and the peel strength between the mixture layer of the obtained electrode and the current collector is a high value in each case, and the binding property is excellent.
  • Example 12 a crosslinked polymer was stably obtained even under conditions of a high monomer concentration of 20%, and the binder containing the crosslinked polymer showed excellent binding properties.
  • cross-linked polymers (salts) R-21 and R-22 are examples in which the polymerization reaction was carried out in the absence of the organic amine compound, and the obtained cross-linked polymer was stable under high monomer concentration conditions. The properties were insufficient, and the average particle size and the particle size distribution were large. Further, even in the evaluation as these binders, sufficient binding properties were not obtained (Comparative Examples 1 and 2).
  • the binder for a non-aqueous electrolyte secondary battery electrode of the present invention exhibits excellent binding ability in the mixture layer, and therefore, a non-aqueous electrolyte secondary battery provided with an electrode obtained using the above-mentioned binder is excellent. It is expected to exhibit good durability (cycle characteristics), and is expected to be applied to automotive secondary batteries. Moreover, it is useful also for use of the active material containing a silicon

Abstract

This specification provides an aqueous binder for non-aqueous electrolyte secondary batteries, as well as a composition for non-aqueous electrolyte secondary battery electrode mixture layers and a non-aqueous electrolyte secondary battery electrode obtained using said binder. The binder contains a cross-linked polymer or salt thereof, and the cross-linked polymer includes a structural unit derived from an ethylenically unsaturated carboxylic acid monomer and is obtained by polymerizing monomer components in the presence of an organic amine compound.

Description

非水電解質二次電池電極用バインダー及びその用途Binder for non-aqueous electrolyte secondary battery electrode and use thereof
　本発明はリチウムイオン二次電池等に使用可能な非水電解質二次電池電極用バインダー及びその用途、並びに、該バインダーに用いられるカルボキシル基含有架橋重合体又はその塩の製造方法に関する。 The present invention relates to a binder for non-aqueous electrolyte secondary battery electrodes that can be used for lithium ion secondary batteries and the like, applications thereof, and a method for producing a carboxyl group-containing crosslinked polymer or a salt thereof used for the binder.
　非水電解質二次電池としては、例えばリチウムイオン二次電池がよく知られている。非水電解質二次電池電極は、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。負極合剤層組成物に用いられるバインダーとしては、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。しかし、近年の環境意識の高まりを背景に、正極合剤層組成物に対しても有機溶剤を使用しない水系化の要求が高まっている。 As a non-aqueous electrolyte secondary battery, for example, a lithium ion secondary battery is well known. The non-aqueous electrolyte secondary battery electrode is produced by applying and drying a composition for forming an electrode mixture layer containing an active material, a binder and the like on a current collector. As a binder used for the negative electrode mixture layer composition, an aqueous binder containing styrene butadiene rubber (SBR) latex and carboxymethyl cellulose (CMC) is used. Moreover, the binder containing acrylic acid type polymer aqueous solution or aqueous dispersion is known as a binder which is excellent in dispersibility and binding property. On the other hand, an N-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride (PVDF) is widely used as a binder used for the positive electrode mixture layer. However, against the background of the recent increase in environmental awareness, there is an increasing demand for a water-based system that does not use an organic solvent, also for the positive electrode mixture layer composition.
　一方、リチウムイオン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 lithium ion secondary batteries is expanded, the demand for improvement in energy density, reliability and durability tends to increase. For example, in order to increase the electric capacity of a lithium ion secondary battery, specifications for 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 as they are used repeatedly, the electrode mixture layer peels off or falls off, resulting in a decrease in battery capacity and cycle characteristics. There is a problem that the (durability) is deteriorated. In order to suppress such a defect, it is generally effective to improve the binding property of the binder, and for the purpose of improving the durability, studies on the binding property improvement of the binder are being conducted.
　出願人は、これまでに、シリコン系活物質を含む電極にも適用可能な結着性に優れるバインダーとして、架橋型アクリル酸系重合体を含むバインダーを開示している。
　例えば、特許文献１では、エチレン性不飽和カルボン酸単量体を構成単量体とし、中和度９０モル％において特定の水分散液粘度を有する架橋重合体（塩）を含むバインダーを開示している。特許文献２では、カルボキシル基を有する架橋重合体又はその塩であって、中和後に塩水中に分散させた際の粒子径が十分小さい重合体を含むバインダーを開示している。 The applicant has hitherto disclosed a binder containing a crosslinkable acrylic acid-based polymer as a binder excellent in binding property applicable to an electrode containing a silicon-based active material.
For example, Patent Document 1 discloses a binder containing a crosslinked polymer (salt) having an ethylenic unsaturated carboxylic acid monomer as a constituent monomer and having a specific aqueous dispersion viscosity at a degree of neutralization of 90 mol%. ing. Patent Document 2 discloses a binder which is a crosslinked polymer having a carboxyl group or a salt thereof, and which has a sufficiently small particle size when dispersed in brine after neutralization.
国際公開第２０１６／１５８９３９号International Publication No. 2016/158939 国際公開第２０１７／０７３５８９号International Publication No. 2017/073589
　特許文献１及び２に開示されるバインダーはいずれも優れた結着性を有するものであるが、リチウムイオン二次電池の性能向上に伴い、より結着力の高いバインダーを求める要求が高まりつつある。
　一般に、結着性を高めるためには、バインダーとなる重合体の分子量を高めることが効果的である。また、分子量の高い重合体を製造するためには、モノマー濃度の高い条件で重合反応を行うことが有効であることが知られている。さらに、得られる重合体は、分散安定性に優れ、電極組成物中において、合一等することなく小粒子の重合体粒子として存在するものの方が、電極合剤層における均一分散性に優れるとともに、活物質等との接着点が増えるため、結着性を向上する観点からも好ましいと考えられる。
　特許文献１に記載のバインダーは、実施例において、２０質量％を超える高い単量体濃度で重合して得られた架橋重合体が開示されているが、結着性には更なる向上の余地があった。架橋重合体の粒子径が十分小さいものでない点に起因するものと推定される。特許文献２に記載のバインダーも優れた結着性を示すことが開示されているが、実施例において開示されている各架橋重合体の重合時の単量体濃度は、約１０質量％程度である。特許文献２に記載の架橋重合体について、結着性の更なる改善を目的に重合時の単量体濃度を高めた場合には、重合安定性及び重合体の分散安定性が十分ではなく、結着性を大きく改善することは難しいことが分かった。 The binders disclosed in Patent Documents 1 and 2 both have excellent binding properties, but with the improvement of the performance of lithium ion secondary batteries, there is an increasing demand for binders having higher binding power.
Generally, in order to improve the binding property, it is effective to increase the molecular weight of the polymer to be a binder. Moreover, in order to manufacture a polymer with high molecular weight, it is known that it is effective to carry out a polymerization reaction under conditions of high monomer concentration. Furthermore, the polymer obtained is excellent in dispersion stability, and in the electrode composition, those which exist as polymer particles of small particles without being united are more excellent in uniform dispersion in the electrode mixture layer. Since the adhesion point with the active material and the like increases, it is considered preferable also from the viewpoint of improving the binding property.
Although the crosslinked polymer obtained by superposing | polymerizing by the high monomer concentration which exceeds 20 mass% is disclosed in the Example as for the binder of patent document 1, room for the further improvement in binding property is disclosed. was there. It is presumed that the particle size of the crosslinked polymer is not sufficiently small. Although it is disclosed that the binder described in Patent Document 2 also exhibits excellent binding properties, the monomer concentration at the time of polymerization of each crosslinked polymer disclosed in the examples is about 10 mass% or so is there. With respect to the crosslinked polymer described in Patent Document 2, when the monomer concentration at the time of polymerization is increased for the purpose of further improving the binding property, the polymerization stability and the dispersion stability of the polymer are not sufficient, It turned out that it is difficult to greatly improve the cohesion.
　本開示は、このような事情に鑑みてなされたものであり、従来よりも優れた結着性を備える非水電解質二次電池電極用水系バインダーを提供する。また、本開示は、上記バインダーを用いて得られる非水電解質二次電池電極合剤層用組成物及び非水電解質二次電池電極も提供する。 This indication is made in view of such a situation, and provides a water-based binder for nonaqueous electrolyte secondary battery electrodes provided with binding nature superior to before. The present disclosure also provides a composition for a non-aqueous electrolyte secondary battery electrode mixture layer obtained using the binder and a non-aqueous electrolyte secondary battery electrode.
　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、有機アミン化合物存在下、エチレン性不飽和カルボン酸単量体を含む単量体成分を重合して得られた架橋重合体又はその塩を含むバインダーが、電極活物質等によく結着し、当該バインダーを含む電極合剤層は、優れた結着性を示すという知見を得た。本発明はこれらの知見に基づいて完成されたものである。 The present inventors have intensively studied to solve the above problems, and as a result, a crosslinked polymer obtained by polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer in the presence of an organic amine compound or The binder containing the salt was well bound to the electrode active material and the like, and it was found that the electrode mixture layer containing the binder exhibits excellent binding properties. The present invention has been completed based on these findings.
　本発明は以下の通りである。
〔１〕架橋重合体又はその塩を含有する非水電解質二次電池電極用バインダーであって、
　前記架橋重合体は、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を含み、有機アミン化合物存在下、単量体成分を重合して得られたものである、非水電解質二次電池電極用バインダー。
〔２〕前記有機アミン化合物は、当該有機アミン化合物に存在する窒素原子数に対する炭素原子数の比で表される値（Ｃ／Ｎ）が３以上である前記〔１〕に記載の非水電解質二次電池電極用バインダー。
〔３〕前記架橋重合体の重合に用いる単量体の総量に対する前記エチレン性不飽和カルボン酸単量体の濃度が、１０質量％以上、１００質量％以下である前記〔１〕又は〔２〕に記載の非水電解質二次電池電極用バインダー。
〔４〕前記エチレン性不飽和カルボン酸単量体に対する前記有機アミン化合物の使用量が、０．００１モル％以上、４．０モル％以下である前記〔１〕～〔３〕のいずれか一に記載の非水電解質二次電池電極用バインダー。
〔５〕非水電解質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、
　有機アミン化合物存在下、エチレン性不飽和カルボン酸単量体を含む単量体成分を沈殿重合法により重合する重合工程を備える、方法。
〔６〕前記〔１〕～〔４〕のいずれか一に記載のバインダー、活物質及び水を含む非水電解質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〕に記載の非水電解質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〕に記載の非水電解質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非水電解質二次電池電極。 The present invention is as follows.
[1] A binder for a non-aqueous electrolyte secondary battery electrode containing a crosslinked polymer or a salt thereof,
The non-aqueous electrolyte secondary battery, wherein the crosslinked polymer comprises a structural unit derived from an ethylenically unsaturated carboxylic acid monomer, and is obtained by polymerizing a monomer component in the presence of an organic amine compound. Binder for electrodes.
[2] The non-aqueous electrolyte according to [1], wherein the organic amine compound has a value (C / N) represented by a ratio of the number of carbon atoms to the number of nitrogen atoms present in the organic amine compound of 3 or more. Binder for secondary battery electrodes.
[3] The above [1] or [2], wherein the concentration of the ethylenically unsaturated carboxylic acid monomer is 10% by mass or more and 100% by mass or less based on the total amount of monomers used for polymerization of the crosslinked polymer. The binder for nonaqueous electrolyte secondary battery electrodes as described in 4.
[4] Any one of the above-mentioned [1] to [3], wherein the amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is 0.001 mol% or more and 4.0 mol% or less The binder for nonaqueous electrolyte secondary battery electrodes as described in 4.
[5] A method for producing a crosslinked polymer or a salt thereof used as a binder for a non-aqueous electrolyte secondary battery electrode,
A method comprising a polymerization step of polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer by a precipitation polymerization method in the presence of an organic amine compound.
[6] A composition for a non-aqueous electrolyte secondary battery electrode mixture layer, comprising the binder according to any one of the above [1] to [4], an active material and water.
[7] The composition for a non-aqueous electrolyte secondary battery electrode mixture layer according to the above [6], which contains a carbon-based material or a silicon-based material as a negative electrode active material.
[8] A non-aqueous electrolyte secondary battery electrode comprising a mixture layer formed of the composition for a non-aqueous electrolyte secondary battery electrode mixture layer according to the above [6] or [7] on the surface of a current collector .
　本発明の非水電解質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。このため、充放電に伴う活物質の体積変化、及び形状変化によって電極合剤層が劣化することが抑制され、耐久性（サイクル特性）の高い二次電池を得ることが可能となる。 The binder for a non-aqueous electrolyte secondary battery electrode of the present invention exhibits excellent binding to electrode active materials and the like. Moreover, the said binder can exhibit favorable adhesiveness also with a collector. For this reason, while being excellent in binding property, the electrode mixture layer containing the said binder and the electrode provided with this can maintain the integrity. For this reason, it is possible to suppress deterioration of the electrode mixture layer due to volume change and shape change of the active material accompanying charge and discharge, and it is possible to obtain a secondary battery with high durability (cycle characteristics).
　本発明の非水電解質二次電池電極合剤層用組成物は、電極材料に対する良好な結着性と集電体に対する良好な接着性とを有するため、一体性の良好な電極合剤層を形成でき、電極特性の良好な非水電解質二次電池電極を得ることが可能となる。 Since the composition for a non-aqueous electrolyte secondary battery electrode mixture layer of the present invention has a good binding property to the electrode material and a good adhesion to the current collector, the electrode mixture layer having a good integrity can be obtained. It is possible to form a non-aqueous electrolyte secondary battery electrode with good electrode characteristics.
　本発明の非水電解質二次電池電極用バインダーは、架橋重合体又はその塩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、本発明の非水電解質二次電池電極が得られる。 The binder for a non-aqueous electrolyte secondary battery electrode of the present invention contains a crosslinked polymer or a salt thereof, and can be made into an electrode mixture layer composition by mixing with an active material and water. The composition described above may be in the form of a slurry capable of being coated on the current collector, or may be prepared as a wet powder to be able to cope with pressing on the surface of the current collector. The non-aqueous electrolyte secondary battery electrode of the present invention can be obtained by forming a mixture layer formed of the above composition on the surface of a current collector such as a copper foil or an aluminum foil.
　以下に、本発明の非水電解質二次電池電極用バインダー及び当該バインダーに用いられる架橋重合体の製造方法、並びに、当該バインダーを用いて得られる非水電解質二次電池電極合剤層用組成物及び非水電解質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。 Below, the binder for non-aqueous electrolyte secondary battery electrodes of this invention, the manufacturing method of the crosslinked polymer used for the said binder, and the composition for non-aqueous electrolyte secondary battery electrode mixture layers obtained using the said binder And each of the non-aqueous electrolyte secondary battery electrodes will be described in detail.
In the present specification, "(meth) acrylic" means acrylic and / or methacrylic, and "(meth) acrylate" means acrylate and / or methacrylate. Moreover, "(meth) acryloyl group" means an acryloyl group and / or a methacryloyl group.
＜バインダー＞
　本発明のバインダーは、カルボキシル基を有する架橋重合体又はその塩を含む。カルボキシル基を有する架橋重合体又はその塩は、エチレン性不飽和カルボン酸に由来する構造単位を有していてもよい。 <Binder>
The binder of the present invention comprises a crosslinked polymer having a carboxyl group or a salt thereof. The crosslinked polymer having a carboxyl group or a salt thereof may have a structural unit derived from an ethylenically unsaturated carboxylic acid.
＜架橋重合体の構造単位＞
＜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＞
　架橋重合体は、エチレン性不飽和カルボン酸単量体に由来する構造単位（以下、「（ａ）成分」ともいう）を有することができる。架橋重合体が、係る構造単位を有することによりカルボキシル基を有する場合、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。
　上記（ａ）成分は、例えば、エチレン性不飽和カルボン酸単量体を含む単量体を重合することにより架橋重合体に導入することができる。その他にも、（メタ）アクリル酸エステル単量体を（共）重合した後、加水分解することによっても得られる。また、（メタ）アクリルアミド及び（メタ）アクリロニトリル等を重合した後、強アルカリで処理してもよいし、水酸基を有する重合体に酸無水物を反応させる方法であってもよい。 <Structural unit of cross-linked polymer>
<Structural unit derived from ethylenically unsaturated carboxylic acid monomer>
The crosslinked polymer can have a structural unit derived from an ethylenically unsaturated carboxylic acid monomer (hereinafter, also referred to as "component (a)"). When the crosslinked polymer has a carboxyl group by having such a structural unit, the adhesion to the current collector is improved, and the desolvation effect of lithium ions and the ion conductivity are excellent, so the resistance is small and the high rate An electrode with excellent characteristics can be obtained. Moreover, since water swellability is provided, the dispersion stability of the active material and the like in the mixture layer composition can be enhanced.
The component (a) can be introduced into a crosslinked polymer, for example, by polymerizing a monomer containing an ethylenically unsaturated carboxylic acid monomer. In addition, it can also be obtained by (co) polymerizing a (meth) acrylic acid ester monomer and then hydrolyzing it. In addition, after (meth) acrylamide and (meth) acrylonitrile are polymerized, they may be treated with a strong alkali, or a method of reacting an acid anhydride with a polymer having a hydroxyl group may be used.
　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。 Ethylenically unsaturated carboxylic acid monomers include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid; (meth) acrylamidoalkyls such as (meth) acrylamidohexanoic acid and (meth) acrylamidododecanoic acid Carboxylic acid; ethylenically unsaturated monomers having a carboxyl group such as monohydroxyethyl (meth) acrylate, ω-carboxy-caprolactone mono (meth) acrylate, β-carboxyethyl (meth) acrylate, etc. And the like. Alkali neutralized products may be mentioned, and one of them may be used alone, or two or more may be used in combination. Among the above, a polymer having a long primary chain length is obtained because the polymerization rate is large, and a compound having an acryloyl group as a polymerizable functional group is preferable, and acrylic acid is particularly preferable in that the binding ability of the binder is good. 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.
　架橋重合体における（ａ）成分の含有量は、特に限定するものではないが、例えば、架橋重合体の全構造単位に対して１０質量％以上、１００質量％以下含むことができる。かかる範囲で（ａ）成分を含有することで、集電体に対する優れた接着性を容易に確保することができる。下限は、例えば２０質量％以上であり、また例えば３０質量％以上であり、また例えば４０質量％以上である。下限は、５０質量％以上であってもよく、例えば、６０質量％以上であり、また例えば７０質量％以上であり、また例えば８０質量％以上である。また、上限は、例えば、９９質量％以下であり、また例えば９８質量％以下であり、また例えば９５質量％以下であり、また例えば９０質量％以下である。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２０質量％以上、１００質量％以下であり、また例えば３０質量％以上、１００質量％以下であり、また例えば５０質量％以上、９９質量％以下などとすることができる。全構造単位に対する（ａ）成分の割合が１０質量％未満の場合、分散安定性、結着性及び電池としての耐久性が不足する場合があり得る。 Although content of (a) component in a crosslinked polymer is not specifically limited, For example, 10 mass% or more and 100 mass% or less can be contained with respect to the total structural unit of a crosslinked polymer. By containing the component (a) in such a range, excellent adhesion to the current collector can be easily ensured. The lower limit is, for example, 20% by mass or more, for example, 30% by mass or more, and for example, 40% by mass or more. The lower limit may be 50% by mass or more, for example, 60% by mass or more, for example 70% by mass or more, and for example 80% by mass or more. The upper limit is, for example, 99% by mass or less, for example, 98% by mass or less, and for example, 95% by mass or less, and for example, 90% by mass or less. The range may be a combination of such lower limit and upper limit as appropriate, and is, for example, 10% by mass or more and 100% by mass or less, and for example, 20% by mass or more and 100% by mass or less It is 30 mass% or more and 100 mass% or less, and can be, for example, 50 mass% or more and 99 mass% or less. When the ratio of the component (a) to the total structural units is less than 10% by mass, the dispersion stability, the binding property and the durability as a battery may be insufficient.
＜その他の構造単位＞
　本発明の架橋重合体は、（ａ）成分以外に、これらと共重合可能な他のエチレン性不飽和単量体に由来する構造単位（以下、「（ｂ）成分」ともいう。）を含むことができる。（ｂ）成分としては、例えば、スルホン酸基及びリン酸基等のカルボキシ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に由来する構造単位が挙げられる。これらの構造単位は、スルホン酸基及びリン酸基等のカルボキシ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を含む単量体を共重合することにより導入することができる。これらの内でも、（ｂ）成分としては、耐屈曲性良好な電極が得られる観点から非イオン性のエチレン性不飽和単量体に由来する構造単位が好ましく、バインダーの結着性が優れる点で（メタ）アクリルアミド及びその誘導体等が好ましい。また、（ｂ）成分として水中への溶解性が１ｇ／１００ｍｌ以下の疎水性のエチレン性不飽和単量体に由来する構造単位を導入した場合、電極材料と強い相互作用を奏することができ、活物質に対して良好な結着性を発揮することができる。これにより、堅固で一体性の良好な電極合剤層を得ることができるため好ましい。特に脂環構造含有エチレン性不飽和単量体に由来する構造単位が好ましい。 <Other structural units>
The crosslinked polymer of the present invention contains, in addition to the component (a), a structural unit derived from another ethylenically unsaturated monomer copolymerizable therewith (hereinafter, also referred to as "component (b)"). be able to. As component (b), for example, 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 etc. The structural unit derived from is mentioned. These structural units are 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 monomer containing a nonionic ethylenically unsaturated monomer Can be introduced by copolymerization. Among these, as the component (b), a structural unit derived from a nonionic ethylenic unsaturated monomer is preferable from the viewpoint that an electrode with good flexibility is obtained, and the binding property of the binder is excellent. And (meth) acrylamide and derivatives thereof are preferable. When a structural unit derived from a hydrophobic ethylenic unsaturated monomer having a solubility in water of 1 g / 100 ml or less is introduced as the component (b), a strong interaction with the electrode material can be exhibited, Good binding can be exhibited for the active material. This is preferable because it is possible to obtain a firm and integral electrode mixture layer. Particularly preferred is a structural unit derived from an alicyclic structure-containing ethylenic unsaturated monomer.
　（ｂ）成分の割合は、架橋重合体の全構造単位に対し、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、架橋重合体の全構造単位に対して（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。 The proportion of the component (b) can be 0% by mass or more and 90% by mass or less with respect to the total structural units of the crosslinked polymer. 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, and 5% by mass or more and 40% by mass or less 10 mass% or more and 30 mass% or less may be sufficient. Further, when the component (b) is contained in an amount of 1% by mass or more based on the total structural units of the crosslinked polymer, the affinity to the electrolytic solution is improved, and therefore, the effect of improving lithium ion conductivity can also 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、Ｎ－ｎ－ブトキシメチル（メタ）アクリルアミド、Ｎ－イソブトキシメチル（メタ）アクリルアミド等のＮ－アルキル（メタ）アクリルアミド化合物；ジメチル（メタ）アクリルアミド、ジエチル（メタ）アクリルアミド等のＮ，Ｎ－ジアルキル（メタ）アクリルアミド化合物が挙げられ、これらの内の１種を単独で使用してもよいし、２種以上を組み合わせて使用してもよい。 Examples of (meth) acrylamide derivatives include N-alkyl (eg, isopropyl (meth) acrylamide, t-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, etc.) Meta) acrylamide compounds; N, N-dialkyl (meth) acrylamide compounds such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide, etc. may be mentioned, and one of them may be used alone, or two You may use combining the above.
　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 ethylenic unsaturated monomer include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth ) (Meth) acrylic acid cycloalkyl ester which may have an aliphatic substituent such as cyclodecyl acrylate and (meth) acrylic acid cyclododecyl; isobornyl (meth) acrylate; adamantyl (meth) acrylate; ) Dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and cyclohexane dimethanol mono (meth) acrylate and cyclodecane di methanol 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 the above, a compound having an acryloyl group as a polymerizable functional group is preferable in that a polymer having a long primary chain length can be obtained because the polymerization rate is large and the binding ability of the binder is good.
　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等の（メタ）アクリル酸アラルキルエステル化合物；
（メタ）アクリル酸２－メトキシエチル、（メタ）アクリル酸エトキシエチル等の（メタ）アクリル酸アルコキシアルキルエステル化合物；
（メタ）アクリル酸ヒドロキシエチル、（メタ）アクリル酸ヒドロキシプロピル及び（メタ）アクリル酸ヒドロキシブチル等の（メタ）アクリル酸ヒドロキシアルキルエステル化合物等が挙げられ、これらの内の１種を単独で使用してもよいし、２種以上を組み合わせて使用してもよい。活物質との密着性及びサイクル特性の観点からは、（メタ）アクリル酸アラルキルエステル化合物を好ましく用いることができる。 As another nonionic ethylenically unsaturated monomer, you may use (meth) acrylic acid ester, for example. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate and 2-ethylhexyl (meth) acrylate Meta) acrylic acid alkyl ester compounds;
(Meth) acrylic acid aralkyl ester compounds such as phenyl (meth) acrylate, phenylmethyl (meth) acrylate and phenylethyl (meth) acrylate;
(Meth) acrylic acid alkoxy alkyl ester compounds such as 2-methoxyethyl (meth) acrylic acid and ethoxyethyl (meth) acrylic acid;
(Meth) acrylic acid hydroxyalkyl ester compounds such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate and the like, and one of them may be used alone It may be used or two or more may be used in combination. From the viewpoint of adhesion to the active material and cycle characteristics, (meth) acrylic acid aralkyl ester compounds can be preferably used.
　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類等、エーテル結合を有する化合物が好ましく、（メタ）アクリル酸２－メトキシエチルがより好ましい。 From the viewpoint of further improving lithium ion conductivity and high rate properties, compounds having an ether bond, such as (meth) acrylate alkoxyalkyls such as 2-methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, are preferable And 2-methoxyethyl (meth) acrylate are more preferable.
　非イオン性のエチレン性不飽和単量体の中でも、重合速度が速いために一次鎖長の長い重合体が得られ、バインダーの結着力が良好となる点でアクリロイル基を有する化合物が好ましい。また、非イオン性のエチレン性不飽和単量体としては、得られる電極の耐屈曲性が良好となる点でホモポリマーのガラス転移温度（Ｔｇ）が０℃以下の化合物が好ましい。 Among the nonionic ethylenically unsaturated monomers, a compound having an acryloyl group is preferable in that a polymer having a long primary chain length can be obtained because the polymerization rate is fast and the binding ability of the binder is good. Moreover, as a nonionic ethylenically unsaturated monomer, the compound whose glass transition temperature (Tg) of a homopolymer is 0 degrees C or less at the point which the bending resistance of the electrode obtained becomes favorable is preferable.
　架橋重合体は塩であってもよい。塩の種類としては特に限定しないが、リチウム、ナトリウム、カリウム等のアルカリ金属塩；カルシウム塩及びバリウム塩等のアルカリ土類金属塩；マグネシウム塩、アルミニウム塩等のその他の金属塩；アンモニウム塩及び有機アミン塩等が挙げられる。これらの中でも電池特性への悪影響が生じにくい点からアルカリ金属塩及びマグネシウム塩が好ましく、アルカリ金属塩がより好ましい。 The crosslinked polymer may be a salt. Types of salts are not particularly limited, but alkali metal salts such as lithium, sodium and potassium; alkaline earth metal salts such as calcium salts and barium salts; other metal salts such as magnesium salts and aluminum salts; ammonium salts and organic An amine salt etc. are mentioned. Among these, alkali metal salts and magnesium salts are preferable, and alkali metal salts are more preferable, from the viewpoint that an adverse effect on battery characteristics hardly occurs.
＜架橋重合体の態様＞
　本発明の架橋重合体における架橋方法は特に制限されるものではなく、例えば以下の方法による態様が例示される。
１）架橋性単量体の共重合
２）ラジカル重合時のポリマー鎖への連鎖移動を利用
３）反応性官能基を有する重合体を合成後、必要に応じて架橋剤を添加して後架橋
　上記の内でも、操作が簡便であり、架橋の程度を制御し易い点から架橋性単量体の共重合による方法が好ましい。 <Aspect of Cross-linked Polymer>
The crosslinking method in the crosslinked polymer of the present invention is not particularly limited, and an embodiment by the following method is exemplified.
1) Copolymerization of a crosslinkable monomer 2) Use of chain transfer to polymer chain during radical polymerization 3) After synthesis of a polymer having a reactive functional group, a crosslinker is added if necessary and post-crosslinking Among the above, the method by the copolymerization of a crosslinkable monomer is preferable in that the operation is simple and the degree of crosslinking can be easily controlled.
＜架橋性単量体＞
　架橋性単量体としては、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が挙げられる。 <Crosslinkable monomer>
As a crosslinkable monomer, a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups, a monomer having a crosslinkable functional group capable of self-crosslinking such as a hydrolyzable silyl group, etc. It can be mentioned.
　上記多官能重合性単量体は、（メタ）アクリロイル基、アルケニル基等の重合性官能基を分子内に２つ以上有する化合物であり、多官能（メタ）アクリレート化合物、多官能アルケニル化合物、（メタ）アクリロイル基及びアルケニル基の両方を有する化合物等が挙げられる。これらの化合物は、１種のみを単独で用いてもよいし、２種以上を組み合わせて用いてもよい。これらの内でも、均一な架橋構造を得やすい点で多官能アルケニル化合物が好ましく、分子内に複数のアリルエーテル基を有する多官能アリルエーテル化合物が特に好ましい。 The above-mentioned polyfunctional polymerizable monomer is a compound having two or more polymerizable functional groups such as (meth) acryloyl group and alkenyl group in the molecule, and a polyfunctional (meth) acrylate compound, a polyfunctional alkenyl compound, Examples thereof include compounds having both an acryloyl group and an alkenyl group. One of these compounds may be used alone, or two or more thereof may be used in combination. Among these, polyfunctional alkenyl compounds are preferable in that a uniform crosslinked structure can be easily obtained, and polyfunctional allyl ether compounds having a plurality of allyl ether groups in the molecule are particularly preferable.
　多官能（メタ）アクリレート化合物としては、エチレングリコールジ（メタ）アクリレート、プロピレングリコールジ（メタ）アクリレート、１，６－ヘキサンジオールジ（メタ）アクリレート、ポリエチレングリコールジ（メタ）アクリレート、ポリプロピレングリコールジ（メタ）アクリレート等の２価アルコールのジ（メタ）アクリレート類；トリメチロールプロパントリ（メタ）アクリレート、トリメチロールプロパンエチレンオキサイド変性体のトリ（メタ）アクリレート、グリセリントリ（メタ）アクリレート、ペンタエリスリトールトリ（メタ）アクリレート、ペンタエリスリトールテトラ（メタ）アクリレート等の３価以上の多価アルコールのトリ（メタ）アクリレート、テトラ（メタ）アクリレート等のポリ（メタ）アクリレート；メチレンビスアクリルアミド、ヒドロキシエチレンビスアクリルアミド等のビスアミド類等を挙げることができる。 Examples of polyfunctional (meth) acrylate compounds include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol Di) (meth) acrylates of dihydric alcohols such as meta) acrylate; trimethylolpropane tri (meth) acrylate, tri (meth) acrylate of trimethylol propane ethylene oxide modified product, glycerin tri (meth) acrylate, pentaerythritol tri ( Poly (meth) acrylates such as tri (meth) acrylates and tetra (meth) acrylates of trivalent or higher polyhydric alcohols such as meth) acrylates and pentaerythritol tetra (meth) acrylates Relate; methylenebisacrylamide, it can be mentioned bisamides such as hydroxyethylene bisacrylamide.
　多官能アルケニル化合物としては、トリメチロールプロパンジアリルエーテル、トリメチロールプロパントリアリルエーテル、ペンタエリスリトールジアリルエーテル、ペンタエリスリトールトリアリルエーテル、テトラアリルオキシエタン、ポリアリルサッカロース等の多官能アリルエーテル化合物；ジアリルフタレート等の多官能アリル化合物；ジビニルベンゼン等の多官能ビニル化合物等を挙げることができる。 As polyfunctional alkenyl compounds, polyfunctional allyl ether compounds such as trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, polyallyl saccharose; diallyl phthalate and the like And polyfunctional vinyl compounds such as divinylbenzene.
　（メタ）アクリロイル基及びアルケニル基の両方を有する化合物としては、（メタ）アクリル酸アリル、（メタ）アクリル酸イソプロペニル、（メタ）アクリル酸ブテニル、（メタ）アクリル酸ペンテニル、（メタ）アクリル酸２－（２－ビニロキシエトキシ）エチル等を挙げることができる。 Examples of compounds having both (meth) acryloyl group and alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl and the like can be mentioned.
　上記自己架橋可能な架橋性官能基を有する単量体の具体的な例としては、加水分解性シリル基含有ビニル単量体、Ｎ－メチロール（メタ）アクリルアミド、Ｎ－メトキシアルキル（メタ）アクリレート等が挙げられる。これらの化合物は、１種単独であるいは２種以上を組み合わせて用いることができる。 Specific examples of the monomer having a crosslinkable functional group that is self-crosslinkable include hydrolyzable silyl group-containing vinyl monomers, N-methylol (meth) acrylamide, N-methoxyalkyl (meth) acrylate, etc. Can be mentioned. These compounds can be used singly or in combination of two or more.
　加水分解性シリル基含有ビニル単量体としては、加水分解性シリル基を少なくとも１個有するビニル単量体であれば、特に限定されない。例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルメチルジメトキシシラン、ビニルジメチルメトキシシランン等のビニルシラン類；アクリル酸トリメトキシシリルプロピル、アクリル酸トリエトキシシリルプロピル、アクリル酸メチルジメトキシシリルプロピル等のシリル基含有アクリル酸エステル類；メタクリル酸トリメトキシシリルプロピル、メタクリル酸トリエトキシシリルプロピル、メタクリル酸メチルジメトキシシリルプロピル、メタクリル酸ジメチルメトキシシリルプロピル等のシリル基含有メタクリル酸エステル類；トリメトキシシリルプロピルビニルエーテル等のシリル基含有ビニルエーテル類；トリメトキシシリルウンデカン酸ビニル等のシリル基含有ビニルエステル類等を挙げることができる。 The hydrolyzable silyl group-containing vinyl monomer is not particularly limited as long as it is a vinyl monomer having at least one hydrolyzable silyl group. For example, vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, etc .; silyl such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylate and the like Silyl group-containing methacrylic acid esters such as trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilyl propyl methacrylate; trimethoxysilylpropyl vinyl ether etc. And silyl group-containing vinyl esters such as vinyl trimethoxysilyl undecanoate.
　架橋重合体が架橋性単量体により架橋されたものである場合、上記架橋性単量体の使用量は、架橋性単量体以外の単量体（非架橋性単量体）の総量に対して０．０２～０．７モル％であることが好ましく、０．０３～０．４モル％であることがより好ましい。架橋性単量体の使用量が０．０２モル％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。０．７モル％以下であれば、架橋重合体の安定性が高くなる傾向がある。 When the crosslinked polymer is crosslinked by a crosslinking monomer, the amount of the crosslinking monomer used is the total amount of monomers (non-crosslinking monomers) other than the crosslinking monomer. The amount is preferably 0.02 to 0.7 mol%, more preferably 0.03 to 0.4 mol%. If the amount of use of the crosslinkable monomer is 0.02 mol% or more, it is preferable in that the binding property and the stability of the mixture layer slurry become better. If it is 0.7 mol% or less, the stability of the crosslinked polymer tends to be high.
＜架橋重合体の粒子径＞
　架橋重合体の粒子径には特段の制限はないが、合剤層組成物において、架橋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場合、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>
The particle size of the crosslinked polymer is not particularly limited. However, in the mixture layer composition, water having an appropriate particle size without the crosslinked polymer being present as a large particle size block (secondary aggregate) When it is well dispersed as swollen particles, a binder containing the crosslinked polymer is preferable because it can exhibit good binding performance.
　例えば、本発明の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、１０μｍ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０．２μｍ以上、５．０μｍ以下であり、さらに好ましい範囲は０．５μｍ以上、３．０μｍ以下である。粒子径が０．１μｍ以上、１０μｍ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１０μｍ以下であれば、十分な結着性を示すことができる。粒子径が０．１μｍ以上であれば、架橋重合体を安定に製造することができる。
　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。 For example, the particle size of the crosslinked polymer of the present invention or the salt thereof when dispersed in water having a degree of neutralization of 80 to 100 mol% based on the carboxyl group of the crosslinked polymer (water swelled particle size Is preferably in the range of 0.1 μm or more and 10 μm or less in terms of volume-based median diameter. A more preferable range of the particle diameter is 0.2 μm or more and 5.0 μm or less, and a further preferable range is 0.5 μm or more and 3.0 μm or less. If the particle size is in the range of 0.1 μm or more and 10 μm or less, the particle size is uniform and suitable in the mixture layer composition, so the stability of the mixture layer composition is high and the binding property is excellent. It is possible to demonstrate If the particle size is 10 μm or less, sufficient binding properties can be exhibited. If the particle size is 0.1 μm or more, a crosslinked polymer can be stably produced.
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０．１～１０μｍ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 cross-linked polymer is unneutralized or less than 80 mol% neutralization degree, neutralize to 80 to 100 mol% neutralization degree with alkali metal hydroxide etc. and measure the particle size when dispersed in water do it. In general, in the case of a powder or a solution (dispersion liquid), the crosslinked polymer or a salt thereof often exists as a lumped particle in which primary particles are associated and aggregated. When the particle size in the above water dispersion is in the above range, the cross-linked polymer or the salt thereof has extremely excellent dispersibility, and it is neutralized to a neutralization degree of 80 to 100 mol% to be water. By dispersing, lumped particles are loosened, and even if it is a dispersion of primary particles or a secondary aggregate, a stable dispersion state is formed with the particle diameter in the range of 0.1 to 10 μm. is there.
　水膨潤粒子径の体積平均メジアン径を個数平均メジアン径で除した値である粒子径分布は、結着性の観点から好ましくは１０以下であり、より好ましくは３．０以下であり、さらに好ましくは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 average median size of the water-swelled particle size by the number average median size, is preferably 10 or less, more preferably 3.0 or less, further preferably from the viewpoint of binding properties. Is 1.5 or less. The lower limit of the particle size distribution is usually 1.0.
　また、本発明の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。
　なお、上記乾燥粒子径は、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 particle size (dry particle size) of the crosslinked polymer of the present invention or a salt thereof at the time of drying is preferably in the range of 0.03 μm or more and 3 μm or less on a volume basis 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.
In addition, the said dry particle diameter can be measured by the method as described in this-application Example.
　一般に、架橋重合体は、そのポリマー鎖の長さ（一次鎖長）が長いほど強靭さが増大し、高い結着性を得ることが可能となるとともに、その水分散液の粘度が上昇する。また、長い一次鎖長を有するポリマーに比較的少量の架橋を施して得られた架橋重合体（塩）は、水中では水に膨潤したミクロゲル体として存在する。本発明の電極合剤層用組成物においては、このミクロゲル体の相互作用により増粘効果や分散安定化効果が発現される。ミクロゲル体の相互作用はミクロゲル体の水膨潤度、およびミクロゲル体の強度によって変化するが、これらは架橋重合体の架橋度により影響を受ける。架橋度が低すぎる場合はミクロゲルの強度が不足して、分散安定化効果や結着性が不足する場合がある。一方架橋度が高すぎる場合は、ミクロゲルの膨潤度が不足して分散安定化効果や結着性が不足する場合がある。すなわち、架橋重合体としては、十分に長い一次鎖長を有する重合体に適度な架橋を施した微架橋重合体であることが望ましい。 In general, as the length of the polymer chain (primary chain length) of the crosslinked polymer increases, the toughness increases, and it becomes possible to obtain high bondability, and the viscosity of the aqueous dispersion increases. In addition, a crosslinked polymer (salt) obtained by applying a relatively small amount of crosslinking to a polymer having a long primary chain length exists in water as a water-swollen microgel body. In the composition for an electrode mixture layer of the present invention, the thickening effect and the dispersion stabilizing effect are exhibited by the interaction of the microgel body. The interaction of the microgel body changes depending on the degree of water swelling of the microgel body and the strength of the microgel body, but these are influenced by the degree of crosslinking of the crosslinked polymer. When the degree of crosslinking is too low, the strength of the microgel may be insufficient, and the dispersion stabilization effect and the binding property may be insufficient. On the other hand, when the degree of crosslinking is too high, the degree of swelling of the microgel may be insufficient, and the dispersion stabilizing effect and the binding property may be insufficient. That is, it is desirable that the crosslinked polymer be a finely crosslinked polymer obtained by appropriately crosslinking the polymer having a sufficiently long primary chain length.
　架橋重合体又はその塩は、合剤層組成物中において、中和度が２０～１００モル％となるように、エチレン性不飽和カルボン酸単量体由来のカルボキシル基等の酸基が中和され、塩の態様として用いることが好ましい。上記中和度は５０～１００モル％であることがより好ましく、６０～９５モル％であることがさらに好ましい。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 cross-linked polymer or the salt thereof, acid groups such as carboxyl groups derived from ethylenically unsaturated carboxylic acid monomers are neutralized so that the degree of neutralization in the mixture layer composition is 20 to 100 mol%. And is preferably used as a salt embodiment. The degree of neutralization is more preferably 50 to 100 mol%, and still more preferably 60 to 95 mol%. When the degree of neutralization is 20 mol% or more, it is preferable in that the water swellability is good and the dispersion stabilizing effect is easily obtained. In the present specification, the above-mentioned degree of neutralization can be calculated by calculation from charged values of a monomer having an acid group such as a carboxyl group and a neutralizing agent used for neutralization. The degree of neutralization is determined by IR measurement of the powder after drying the crosslinked polymer or its salt at 80 ° C. for 3 hours under reduced pressure conditions, the peak derived from the C = O group of carboxylic acid and C = of carboxylic acid salt It can confirm from the intensity ratio of the peak derived from O group.
＜架橋重合体又はその塩の製造方法＞
　架橋重合体は、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 of Producing Crosslinked Polymer or Salt Thereof>
The cross-linked polymer may be a known polymerization method such as solution polymerization, precipitation polymerization, suspension polymerization or emulsion polymerization, but precipitation polymerization and suspension polymerization (reverse phase suspension polymerization) in terms of productivity Is preferred. Heterogeneous polymerization methods such as precipitation polymerization, suspension polymerization, and emulsion polymerization are preferable, and precipitation polymerization is more preferable, from the viewpoint of obtaining better performance with regard to binding properties and the like.
Precipitation polymerization is a method of producing a polymer by carrying out a polymerization reaction in a solvent which dissolves the raw material unsaturated monomer 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 liquid of polymer particles in which primary particles of several tens of nm to several hundreds of nm are secondarily aggregated to several μm to several tens of μm is obtained. Dispersion stabilizers can also be used to control the particle size of the polymer.
The above secondary aggregation can also 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, as the polymerization solvent, a solvent selected from water, various organic solvents and the like can be used in consideration of the kind of the monomer to be used and the like. 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。本発明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 1 type can be used individually or in combination of 2 or more types. Or you may use as a mixed solvent of these and water. In the present invention, the water-soluble solvent means one having a solubility in water at 20 ° C. of more than 10 g / 100 ml.
Among the above, formation of coarse particles and adhesion to a reactor are small and polymerization stability is good, and precipitated polymer fine particles are less likely to cause secondary aggregation (or even if secondary aggregation occurs, they are dispersed in an aqueous medium Methyl ethyl ketone and acetonitrile are preferable in that they are easy), that a polymer having a small chain transfer constant and a large polymerization degree (primary chain length) can be obtained, and that the operation is easy in 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０．０５～１０．０質量％であり、より好ましくは０．１～５．０質量％、さらに好ましくは０．１～１．０質量％である。高極性溶媒の割合が０．０５質量％以上であれば、上記中和反応への効果が認められ、１０．０質量％以下であれば重合反応への悪影響も見られない。また、アクリル酸等の親水性の高いエチレン性不飽和カルボン酸単量体の重合では、高極性溶媒を加えた場合には重合速度が向上し、一次鎖長の長い重合体を得やすくなる。高極性溶媒の中でも特に水は上記重合速度を向上させる効果が大きく好ましい。 In addition, it is preferable to add a small amount of a highly polar solvent to the polymerization solvent in order to allow the neutralization reaction to proceed stably and rapidly in the process neutralization. Such high polar solvents preferably include water and methanol. The amount of the highly polar solvent used is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and still more preferably 0.1 to 1 based on the total mass of the medium. It is .0 mass%. If the proportion of the high polar solvent is 0.05% by mass or more, the effect on the above-mentioned neutralization reaction is observed, and if it is 10.0% by mass or less, no adverse effect on the polymerization reaction is observed. Further, in the polymerization of a highly hydrophilic ethylenic unsaturated carboxylic acid monomer such as acrylic acid, when a highly polar solvent is added, the polymerization rate is improved, and a polymer having a long primary chain length can be easily obtained. Among the highly polar solvents, water is particularly preferable because the effect of improving the polymerization rate is large.
　本発明では、架橋重合体は、有機アミン化合物の存在下、エチレン性不飽和カルボン酸単量体を含む単量体成分を重合することにより得られる。このようにして得られた架橋重合体又はその塩を含むバインダーは高い結着性を発揮することができる。
　また、有機アミン化合物の存在下において、エチレン性不飽和カルボン酸単量体を含む単量体成分を重合した場合には、重合安定性が向上し、高い単量体濃度であっても架橋重合体を安定に製造することができる。上記単量体濃度は、例えば１０．０質量％以上程度であってもよいが、結着性の観点から好ましくは１３．０質量％以上である。単量体濃度はより好ましくは１５．０質量％以上であり、更に好ましくは１７．０質量％以上であり、一層好ましくは１９．０質量％以上である。単量体濃度はなお好ましくは２０．０質量％以上であり、より一層好ましくは２２．０質量％以上であり、更に一層好ましくは２５．０質量％以上である。一般に、重合時の単量体濃度を高くするほど高分子量化が可能であり、一次鎖長の長い重合体を製造することができる。本発明の架橋重合体は、十分に長い一次鎖長を有する重合体に適度な架橋を施した微架橋重合体であるため、その一次鎖長を直接測定することは、分析的に困難である。一般的には、重合体の一次鎖長は溶液粘度と相関することが知られているが、架橋重合体の場合にはその架橋度によっても溶液粘度は変動する。よって、上記の方法で得られた架橋重合体を、当該重合体の構造又は特性で規定することは非常に困難である。
　なお、本明細書において「単量体濃度」とは、重合を開始する時点における反応液中の単量体濃度を示す。 In the present invention, a crosslinked polymer is obtained by polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer in the presence of an organic amine compound. The binder containing the crosslinked polymer or the salt thereof thus obtained can exhibit high binding properties.
In addition, when the monomer component containing the ethylenically unsaturated carboxylic acid monomer is polymerized in the presence of the organic amine compound, the polymerization stability is improved, and the crosslinking weight is increased even at a high monomer concentration. The uniting can be produced stably. The monomer concentration may be, for example, about 10.0% by mass or more, but is preferably 13.0% by mass or more from the viewpoint of binding properties. The monomer concentration is more preferably 15.0% by mass or more, still more preferably 17.0% by mass or more, and still more preferably 19.0% by mass or more. The monomer concentration is more preferably 20.0% by mass or more, still more preferably 22.0% by mass or more, and still more preferably 25.0% by mass or more. Generally, the higher the monomer concentration at the time of polymerization, the higher the molecular weight can be obtained, and a polymer having a long primary chain length can be produced. Since the crosslinked polymer of the present invention is a finely crosslinked polymer obtained by appropriately crosslinking the polymer having a sufficiently long primary chain length, direct measurement of the primary chain length is analytically difficult. . In general, the primary chain length of a polymer is known to be correlated with the solution viscosity, but in the case of a crosslinked polymer, the solution viscosity also varies depending on the degree of crosslinking. Therefore, it is very difficult to define the crosslinked polymer obtained by the above method by the structure or characteristics of the polymer.
In the present specification, “monomer concentration” refers to the monomer concentration in the reaction liquid at the time of initiating polymerization.
　単量体濃度の上限値は、使用する単量体及び溶媒の種類、並びに、重合方法及び各種重合条件等により異なるが、重合反応熱の除熱が可能であれば、沈殿重合では概ね４０％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 types of monomers and solvents used, and the polymerization method and various polymerization conditions, but if heat removal from the polymerization reaction is possible, it is approximately 40% in precipitation polymerization. The degree is about 50% in suspension polymerization and about 70% in emulsion polymerization.
　上記の通り、有機アミン化合物存在下において重合反応を行うことにより、結着性に優れる架橋重合体を得ることができる。さらに、例えば１３．０質量％を超えるような高い単量体濃度条件下であっても、重合反応を安定に実施することができる。このような高い単量体濃度で重合して得られた重合体は、分子量が高いため（一次鎖長が長いため）結着性にも優れる。 As described above, by performing the polymerization reaction in the presence of the organic amine compound, it is possible to obtain a crosslinked polymer having excellent binding properties. Furthermore, the polymerization reaction can be stably carried out even under high monomer concentration conditions, for example, exceeding 13.0% by mass. A polymer obtained by polymerization at such a high monomer concentration is excellent in binding ability because of its high molecular weight (because of the long primary chain length).
　有機アミン化合物としては、アンモニアの他、例えば、モノメチルアミン、ジメチルアミン、トリメチルアミン、モノエチルアミン、ジエチルアミン、トリエチルアミン、モノブチルアミン、ジブチルアミン、トリブチルアミン、モノヘキシルアミン、ジヘキシルアミン、トリヘキシルアミン、トリオクチルアミン及びトリドデシルアミン等のＮ－アルキル置換アミン；モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、プロパノールアミン、ジメチルエタノールアミン及びＮ，Ｎ－ジメチルエタノールアミン等の（アルキル）アルカノールアミン；ピリジン、ピペリジン、ピペラジン、１，８－ビス（ジメチルアミノ）ナフタレン、モルホリン及びジアザビシクロウンデセン（ＤＢＵ）等の環状アミン；ジエチレントリアミン、Ｎ、Ｎ－ジメチルベンジルアミンが挙げられ、これらの内の１種又は２種以上を用いることができる。
　これらの内でも、結着性の観点からアンモニアを除く有機アミン化合物が好ましい。また、長鎖アルキル基を有する疎水性アミンを用いた場合、より大きな静電反発及び立体反発が得られることから、単量体濃度の高い場合であっても重合安定性を確保しやすい点で好ましい。具体的には、有機アミン化合物に存在する窒素原子数に対する炭素原子数の比で表される値（Ｃ/Ｎ）が高い程、立体反発効果による重合安定化効果が高い。上記Ｃ／Ｎの値は、好ましくは３以上であり、より好ましくは５以上であり、さらに好ましくは１０以上であり、一層好ましくは２０以上である。 As the organic amine compound, other than ammonia, for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monobutylamine, dibutylamine, tributylamine, monohexylamine, dihexylamine, trihexylamine, trioctylamine And N-alkyl substituted amines such as tridodecylamine; (alkyl) alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, propanolamine, dimethylethanolamine and N, N-dimethylethanolamine; pyridine, piperidine, piperazine, Cyclic amines such as 1,8-bis (dimethylamino) naphthalene, morpholine and diazabicycloundecene (DBU); diethylene tri Min, N, N-dimethylbenzylamine, and the like, may be used alone or two or more of these.
Among these, organic amine compounds other than ammonia are preferable from the viewpoint of binding ability. In addition, when a hydrophobic amine having a long chain alkyl group is used, larger electrostatic repulsion and steric repulsion can be obtained, so that the polymerization stability can be easily secured even when the monomer concentration is high. preferable. Specifically, the higher the value (C / N) represented by the ratio of the number of carbon atoms to the number of nitrogen atoms present in the organic amine compound, the higher the polymerization stabilization effect by the steric repulsion effect. The value of C / N is preferably 3 or more, more preferably 5 or more, further preferably 10 or more, and still more preferably 20 or more.
　Ｃ／Ｎ値の高いアミン化合物は、一般的には疎水性が高く、アミン価の低い化合物である。上記の通り、Ｃ／Ｎ値が高いアミン化合物は高い重合安定化効果を示す傾向があり、重合時の単量体濃度を高くすることが可能となるため、重合体が高分子量化（一次鎖長の増大）され、結着性が向上する傾向がある。また、Ｃ／Ｎ値の高いアミン化合物の存在下において重合を行った場合、粒子径の小さい架橋重合体又はその塩が得られる傾向がある。このため、活物質等との接着性が増加し、結着性が向上する。 An amine compound having a high C / N value is generally a compound having a high hydrophobicity and a low amine value. As described above, an amine compound having a high C / N value tends to exhibit a high polymerization stabilization effect, and it becomes possible to increase the monomer concentration at the time of polymerization, so that the polymer has a high molecular weight (primary chain And the integrity tends to be improved. When polymerization is performed in the presence of an amine compound having a high C / N value, a crosslinked polymer having a small particle size or a salt thereof tends to be obtained. Therefore, the adhesion to the active material and the like is increased, and the binding property is improved.
　本製造方法では、エチレン性不飽和カルボン酸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。例えば、（ａ）成分の由来となるエチレン性不飽和カルボン酸単量体を１０質量％以上、１００質量％以下、及び（ｂ）成分の由来となる他のエチレン性不飽和単量体０質量％以上、９０質量％以下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。
　上記重合工程により、架橋重合体には、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）が１０質量％以上、１００質量％以下導入される。エチレン性不飽和カルボン酸単量体の使用量は、また例えば、２０質量％以上、１００質量％以下であり、また例えば、３０質量％以上、１００質量％以下であり、また例えば、５０質量％以上、９９質量％以下である。均一性に優れた小粒子径の重合体微粒子を得易い点で、上記重合工程は、沈殿重合法によることが好ましい。 In the present production method, it is preferable to include a polymerization step of polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer. For example, 10% by mass or more and 100% by mass or less of the ethylenically unsaturated carboxylic acid monomer from which the component (a) is derived, and 0 mass of another ethylenically unsaturated monomer from which the component (b) is derived It is preferable to have a polymerization step of polymerizing a monomer component containing% or more and 90% by mass or less.
The structural unit (component (a)) derived from the ethylenically unsaturated carboxylic acid monomer is introduced into the crosslinked polymer in an amount of 10% by mass or more and 100% by mass or less through the polymerization step. The use amount of the ethylenically unsaturated carboxylic acid monomer is also, for example, 20% by mass or more and 100% by mass or less, and for example, 30% by mass or more and 100% by mass or less, for example, 50% by mass Above, it is 99 mass% or less. The polymerization step is preferably performed by a precipitation polymerization method in that a polymer particle having a small particle size excellent in uniformity is easily obtained.
　重合時には、上記エチレン性不飽和カルボン酸単量体に対し、０．００１モル％以上の有機アミン化合物を用いることが好ましい。０．００１モル％以上の有機アミン化合物存在下で重合反応を行うことにより、重合安定性を向上することができ、高い単量体濃度条件でも円滑に重合反応が進行する。エチレン性不飽和カルボン酸単量体に対する有機アミン化合物の使用量は、好ましくは０．０１モル％以上であり、より好ましくは０．０３モル％以上であり、さらに好ましくは０．０５モル％以上である。有機アミン化合物の使用量は、０．３モル％以上であってもよく、０．５モル％以上であってもよい。
　また、有機アミン化合物の使用量の上限は、４．０モル％以下であることが好ましい。４．０モル％以下の有機アミン化合物存在下で重合反応を行うことにより、重合安定性を向上することができ、高い単量体濃度条件でも円滑に重合反応が進行する。エチレン性不飽和カルボン酸単量体に対する有機アミン化合物の使用量は、好ましくは３．０モル％以下であり、より好ましくは２．０モル％以下であり、さらに好ましくは１．０モル％以下である。
　尚、本明細書では、有機アミン化合物の使用量は、エチレン性不飽和カルボン酸単量体に対して用いた有機アミン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、用いる有機アミン化合物の価数は考慮しない。 At the time of polymerization, it is preferable to use an organic amine compound of 0.001 mol% or more with respect to the above-mentioned ethylenically unsaturated carboxylic acid monomer. By conducting the polymerization reaction in the presence of 0.001 mol% or more of the organic amine compound, the polymerization stability can be improved, and the polymerization reaction proceeds smoothly even under high monomer concentration conditions. The amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, and still more preferably 0.05 mol% or more It is. The amount of the organic amine compound used may be 0.3 mol% or more, or 0.5 mol% or more.
Moreover, it is preferable that the upper limit of the usage-amount of an organic amine compound is 4.0 mol% or less. By conducting the polymerization reaction in the presence of an organic amine compound of 4.0 mol% or less, the polymerization stability can be improved, and the polymerization reaction smoothly proceeds even under high monomer concentration conditions. The amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is preferably 3.0 mol% or less, more preferably 2.0 mol% or less, and still more preferably 1.0 mol% or less It is.
In the present specification, the amount of the organic amine compound used represents the molar concentration of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer, and means the degree of neutralization. Absent. That is, the valence of the organic amine compound used is not considered.
　本製造方法では、上記エチレン性不飽和カルボン酸単量体以外にも、これと共重合可能な他のエチレン性不飽和単量体を単量体成分として含んでよい。当該他のエチレン性不飽和単量体としては、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、並びに、非イオン性のエチレン性不飽和単量体等が挙げられる。具体的な化合物としては、上述した（ｂ）成分を導入可能な単量体化合物が挙げられる。上記他のエチレン性不飽和単量体は、単量体成分の全量に対して０質量％以上、９０質量％以下含んでもよく、１質量％以上、６０質量％以下であってもよく、５質量％以上、５０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、同様に上記架橋性単量体を使用してもよい。 In the present production method, in addition to the above-mentioned ethylenically unsaturated carboxylic acid monomer, another ethylenically unsaturated monomer copolymerizable therewith may be contained as a monomer component. As the other ethylenically unsaturated monomer, for example, 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, and a nonionic ethylenic character Unsaturated monomer etc. are mentioned. As a specific compound, the monomer compound which can introduce | transduce the component (b) mentioned above is mentioned. The other ethylenically unsaturated monomer may be contained in an amount of 0% by mass or more and 90% by mass or less, or 1% by mass or more and 60% by mass or less based on the total amount of the monomer components. The content may be 50% by mass or more, and 10% by mass or more and 30% by mass or less. Moreover, you may use the said crosslinkable monomer similarly.
　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。 As the polymerization initiator, known polymerization initiators such as azo compounds, organic peroxides and inorganic peroxides can be used, but are not particularly limited. The conditions of use can be adjusted by a known method such as heat initiation, redox initiation in combination with a reducing agent, UV initiation, etc., 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 such that the amount of radical generation is smaller within the allowable range of production time.
　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。 As the above azo compounds, 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) and the like, and one or more of these may be 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 (also "perhexa HC"), 1,1-di (t-butylperoxy) cyclohexane (also "perhexa C"), n-butyl-4,4-di (t-butylperoxy) Barrelate (the same "perhexa V"), 2, 2- di (t- butylperoxy) butane (the same "perhexa 22"), t- butyl hydroperoxide (the same "perbutyl H"), cumene hydroperoxide (the day Oil Co., Ltd., trade name "Percumyl H"), 1,1,3,3-Tetramethylbutyl hydroperoxide (the same "Perocta H"), t-butyl cumyl peroxide (the same Perbutyl C "), di-t-butyl peroxide (the same" perbutyl D "), di-t-hexyl peroxide (the same" perhexyl D "), di (3,5,5-trimethylhexanoyl) peroxide (the same Same as "Paroyl 355"), dilauroyl peroxide (also "Paroyl L"), bis (4-t-butylcyclohexyl) peroxydicarbonate (also "Paroyl TCP"), di-2-ethylhexylperoxydicarbonate Same as "Paroyl OPP"), di-sec-butyl peroxydicarbonate (the same "Paroyl SBP"), cumylperoxy neodecanoate (the same "Parkyl ND"), 1,1,3,3-tetramethylbutyl Peroxy neodecanoate (the same "perocta ND"), t-hexylperoxy neodeca Aate (same "perhexyl ND"), t-butyl peroxy neodecanoate (same "perbutyl ND"), t-butyl peroxy neoheptanoate (same "perbutyl NHP"), t-hexyl peroxy pivalate (Same "Perhexyl PV"), t-Butylperoxypivalate (Same "Perbutyl PV"), 2,5-Dimethyl-2,5-di (2-ethylhexanoyl) hexane (Same "Perhexa 250"), 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexanoate (the same "perocta O"), t-hexylperoxy-2-ethylhexanoate (the same "perhexyl O"), t- Butylperoxy-2-ethylhexanoate (the same "perbutyl O"), t-butylperoxy laurate (the same "perbutyl L"), t-bu Chilperoxy-3,5,5-trimethylhexanoate ("perbutyl 355"), t-hexylperoxyisopropyl monocarbonate ("perhexyl I"), t-butylperoxyisopropyl monocarbonate ("perbutyl I") ), T-Butylperoxy-2-ethylhexyl monocarbonate (also "perbutyl E"), t-butylperoxyacetate (also "perbutyl A"), t-hexylperoxybenzoate (also "perhexyl Z") and t -Butyl peroxybenzoate (the same "perbutyl Z") and the like can be mentioned, 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, sulfur dioxide 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 amount of use of the polymerization initiator is, for example, 0.001 to 2 parts by mass, for example, 0.005 to 1 parts by mass, based on 100 parts by mass of the total amount of the monomer components to be used. For example, it is 0.01 to 0.1 parts by mass. If the amount of the polymerization initiator used is 0.001 parts by mass or more, the polymerization reaction can be stably carried out, and if it is 2 parts by mass or less, a polymer having a long primary chain length can be easily obtained.
　重合時の単量体成分の濃度については、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、単量体成分の濃度が高すぎると、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。本発明の架橋重合体は、重合開始時に１３．０質量％以上の単量体濃度で重合して得られたものであることが好ましい。単量体濃度はより好ましくは１５．０質量％以上であり、更に好ましくは１７．０質量％以上であり、一層好ましくは１９．０質量％以上であり、より一層好ましくは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、最も好ましくは２５．０質量％以上である。
　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 concentration of the monomer component at the time of polymerization is preferably high from the viewpoint of obtaining a polymer having a longer primary chain length. However, if the concentration of the monomer component is too high, aggregation of the polymer particles is likely to proceed, and control of the heat of polymerization is difficult, which may cause runaway of the polymerization reaction. 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. The crosslinked polymer of the present invention is preferably obtained by polymerization at a monomer concentration of 13.0% by mass or more at the start of polymerization. The monomer concentration is more preferably 15.0% by mass or more, further preferably 17.0% by mass or more, still more preferably 19.0% by mass or more, still more preferably 20.0% by mass It is above. The monomer concentration is more preferably 22.0% by mass or more, and most preferably 25.0% by mass or more.
The polymerization temperature is preferably 0 to 100 ° C., and more preferably 20 to 80 ° C., although it depends on conditions such as the type and concentration of monomers to be used. The polymerization temperature may be constant or may change during the polymerization reaction. The polymerization time is preferably 1 minute to 20 hours, more preferably 1 hour to 10 hours.
　重合工程を経て得られた架橋重合体分散液は、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、目的とする架橋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、架橋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。
　架橋重合体粉末中に含まれる残存溶剤及び未反応単量体は、臭気、電池性能及び安全性（ガス化による電池の膨れ等）への懸念等から少ない方が好ましい。具体的には、架橋重合体粉末中、好ましくは２．０質量％以下であり、より好ましくは１．０質量%以下であり、さらに好ましくは０．５質量％以下であり、一層好ましくは０．１質量％以下である。 The crosslinked polymer dispersion obtained through the polymerization step can be subjected to pressure reduction and / or heat treatment or the like in the drying step to distill off the solvent, whereby the target crosslinked polymer can be obtained in the form of powder. Under the present circumstances, solid-liquid separation processes, such as centrifugation and filtration, following a polymerization process for the purpose of removing unreacted monomer (and its salt), impurities derived from an initiator, etc. before the above-mentioned drying process. It is preferable to have a washing step using the same solvent as methanol, or the polymerization solvent. When the above-mentioned washing step is included, even if the crosslinked polymer is secondary-aggregated, it is easy to be entangled at the time of use, and the remaining unreacted monomer is further removed, which is also good in terms of binding ability and battery characteristics. Performance.
The residual solvent and unreacted monomer contained in the crosslinked polymer powder are preferably as small as possible from the viewpoint of odor, battery performance and safety (cell swelling due to gasification, etc.). Specifically, it is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, more preferably 0% by mass in the crosslinked polymer powder. .1% by mass or less.
　本製造方法では、塩基化合物存在下にエチレン性不飽和カルボン酸単量体を含む単量体組成物の重合反応を行うが、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架橋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, a polymerization reaction of a monomer composition containing an ethylenically unsaturated carboxylic acid monomer is carried out in the presence of a base compound, but an alkali compound is added to the polymer dispersion obtained by the polymerization step. After the polymer is neutralized (hereinafter, also referred to as “process neutralization”), the solvent may be removed in the drying step. In addition, after preparing a powder of a crosslinked polymer without performing the process of neutralization in the above steps, an alkali compound is added when preparing the electrode mixture layer slurry to neutralize the polymer (hereinafter referred to as “after It may be called “sum”. Among the above, the process neutralization is preferable because secondary aggregates tend to be easily entangled.
　本製造方法では、架橋重合体は重合工程後のスラリーの状態、または乾燥工程後の粉末の状態において、金属異物を除去する金属除去工程を設けてもよい。金属異物を除去する方法としては特段の制限はなく、格子型マグネット、マグネットストレーナー、マグネットフィルター、電磁分離機、マグネットプーリー、ドラム磁選機及び吊下磁選機等の公知の方法を用いることができる。
　金属除去工程では、数十～数百μｍ以上のサイズの磁性を有する金属異物が除去される。金属異物除去工程後の架橋重合体に含まれる金属異物は、該架橋重合体に対し、好ましくは１０ｐｐｍ以下であり、より好ましくは１ｐｐｍ以下であり、さらに好ましくは０．１ｐｐｍ以下であり、一層好ましくは０．０１ｐｐｍ以下である。 In this production method, the crosslinked polymer may be provided with a metal removal step of removing metal foreign matter in the state of the slurry after the polymerization step or in the state of the powder after the drying step. There is no particular limitation on the method of removing the metal foreign matter, and known methods such as a lattice type magnet, a magnet strainer, a magnet filter, an electromagnetic separator, a magnet pulley, a drum magnetic separator and a suspension magnetic separator can be used.
In the metal removing step, magnetic foreign matter having a size of several tens to several hundreds of μm or more is removed. The amount of foreign metal contained in the crosslinked polymer after the step of removing foreign metal is preferably 10 ppm or less, more preferably 1 ppm or less, still more preferably 0.1 ppm or less, relative to the crosslinked polymer. Is less than 0.01 ppm.
＜非水電解質二次電池電極合剤層用組成物＞
　本発明の非水電解質二次電池電極合剤層用組成物は、上記架橋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架橋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。架橋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、架橋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 Nonaqueous Electrolyte Secondary Battery Electrode Mixture Layer>
The composition for a non-aqueous electrolyte secondary battery electrode mixture layer of the present invention comprises a binder containing the above-described crosslinked polymer or a salt thereof, an active material, and water.
The use amount of the crosslinked polymer or the salt thereof in the electrode mixture layer composition of the present invention is, for example, 0.1% by mass or more and 20% by mass or less with respect to the total amount of the active material. The use amount is also, 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, for example, 0.4% by mass or more and 5% by mass or less . When the amount of use of the crosslinked polymer and the salt thereof is less than 0.1% by mass, sufficient binding properties may not be obtained. In addition, the dispersion stability of the active material and the like may be insufficient, and the uniformity of the formed mixture layer may be reduced. On the other hand, when the use amount of the crosslinked polymer and the salt thereof exceeds 20% by mass, the electrode mixture layer composition may have a high viscosity, and the coatability to the current collector may be reduced. As a result, bumps and irregularities may be generated in the obtained mixture layer, which may adversely affect the electrode characteristics.
　架橋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、上記架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。 When the amount of the crosslinked polymer and the salt thereof used is in the above range, a composition having excellent dispersion stability can be obtained, and a mixture layer having extremely high adhesion to the current collector can be obtained, and the result is As the battery durability improves. Furthermore, the crosslinked polymer and the salt thereof exhibit sufficiently high binding ability even in a small amount (for example, 5% by mass or less) with respect to the active material, and have a carboxy anion, so the interface resistance is small and high rate characteristics are obtained. An excellent electrode is obtained.
　上記活物質の内、正極活物質としては主に遷移金属酸化物のリチウム塩が用いられ、例えば、層状岩塩型及びスピネル型のリチウム含有金属酸化物を使用することができる。層状岩塩型の正極活物質の具体的な化合物としては、コバルト酸リチウム、ニッケル酸リチウム、並びに、三元系と呼ばれるＮＣＭ｛Ｌｉ（Ｎｉx，Ｃｏy，Ｍｎz）、ｘ＋ｙ＋ｚ＝１｝及びＮＣＡ｛Ｌｉ（Ｎｉ1-a-bＣｏaＡｌb）｝等が挙げられる。また、スピネル型の正極活物質としてはマンガン酸リチウム等が挙げられる。酸化物以外にもリン酸塩、ケイ酸塩及び硫黄等が使用され、リン酸塩としては、オリビン型のリン酸鉄リチウム等が挙げられる。正極活物質としては、上記のうちの１種を単独で使用してもよく、２種以上を組み合わせて混合物又は複合物として使用してもよい。 Among the above active materials, lithium salts of transition metal oxides are mainly used as the positive electrode active material, and for example, layered rock salt type and spinel type lithium containing metal oxides can be used. Specific compounds of the positive electrode active material of layered rock-salt, lithium cobaltate, lithium nickelate, and, NCM {Li (Ni x, Co y, Mn z), x + y + z = 1} called ternary and NCA {Li (Ni 1-ab Co a Al b)} , and the like. Moreover, lithium manganate etc. are mentioned as a spinel type positive electrode active material. Besides oxides, phosphates, silicates, sulfur and the like are used, and examples of the phosphate include olivine-type lithium iron phosphate and the like. 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架橋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架橋重合体の使用量は、架橋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。 When a positive electrode active material containing a layered rock salt type lithium-containing metal oxide is dispersed in water, lithium ions on the surface of the active material are exchanged with hydrogen ions in water, whereby the dispersion exhibits alkalinity. For this reason, there is a possibility that aluminum foil (Al) or the like, which is a general current collector material for positive electrode, may be corroded. In such a case, it is preferable to neutralize the alkali component eluted from the active material by using an unneutralized or partially neutralized crosslinked polymer as a binder. In addition, the amount of unneutralized or partially neutralized crosslinked polymer used should be such that the amount of non-neutralized carboxyl groups of the crosslinked polymer is equivalent to or more than the amount of alkali eluted from the active material. Is preferred.
　正極活物質はいずれも電気伝導性が低いため、導電助剤を添加して使用されるのが一般的である。導電助剤としては、カーボンブラック、カーボンナノチューブ、カーボンファイバー、黒鉛微粉、炭素繊維等の炭素系材料が挙げられ、これらの内、優れた導電性を得やすい点からカーボンブラック、カーボンナノチューブ及びカーボンファイバー、が好ましい。また、カーボンブラックとしては、ケッチェンブラック及びアセチレンブラックが好ましい。導電助剤は、上記の１種を単独で使用してもよく、２種以上を組み合わせて使用してもよい。導電助剤の使用量は、導電性とエネルギー密度を両立するという観点から活物質の全量に対して、例えば、０．２～２０質量％とすることができ、また例えば、０．２～１０質量％とすることができる。また正極活物質は導電性を有する炭素系材料で表面コーティングしたものを使用してもよい。 Since all positive electrode active materials have low electrical conductivity, it is generally used by adding a conductive aid. Examples of the conductive aid include carbon-based materials such as carbon black, carbon nanotubes, carbon fibers, graphite fine powder, carbon fibers, etc. Among them, carbon black, carbon nanotubes and carbon fibers from the viewpoint of easily obtaining excellent conductivity. Is preferred. Moreover, as carbon black, ketjen black and acetylene black are preferable. The conductive aids may be used alone or in combination of two or more. The amount of the conductive aid can be, for example, 0.2 to 20% by mass with respect to the total amount of the active material from the viewpoint of achieving both conductivity and energy density, and for example, 0.2 to 10%. It can be mass%. The positive electrode active material may be 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-based materials, lithium metals, lithium alloys, metal oxides and the like, and one or more of these 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 materials”) are preferred, and graphite such as natural graphite and artificial graphite Hard carbon is more preferred. In the case of graphite, spheroidized graphite is preferably used from the viewpoint of battery performance, and the preferable range of the particle size thereof 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 or the like capable of storing lithium such as silicon or tin can also be used as the negative electrode active material. Among them, silicon has a higher capacity than graphite, and active materials composed of silicon materials such as silicon, silicon alloys and silicon oxides such as silicon monoxide (SiO) (hereinafter also referred to as “silicon-based active materials”) Can be used. However, the silicon-based active material has a high capacity, but on the other hand, there is a large volume change due to charge and discharge. For this reason, it is preferable to use together with the said carbon-type active material. In this case, if the compounding amount of the silicon-based active material is large, the electrode material may be broken, and the cycle characteristics (durability) may be significantly reduced. From such a viewpoint, when using a silicon-based active material in combination, the amount used is, for example, 60% by mass or less, and for example, 30% by mass or less with respect to the carbon-based active material.
　本発明の架橋重合体を含むバインダーは、当該架橋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、本発明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 crosslinked polymer of the present invention has a structural unit (component (a)) derived from the ethylenically unsaturated carboxylic acid monomer. Here, the component (a) has a high affinity to the silicon-based active material and exhibits a good binding property. Therefore, since the binder of the present invention exhibits excellent binding even when using a high capacity type active material containing a silicon-based active material, it is also effective for improving the durability of the obtained electrode. It is considered to be 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 aid. When a conductive auxiliary is added for the purpose of further reducing resistance, the amount used is, for example, 10% by mass or less, for example, 5% by mass or less, based on the total amount of active materials from the viewpoint of energy density. It is.
　非水電解質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 a non-aqueous electrolyte 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 with respect to the total amount of the composition. It is in the range of 65% by mass. When the amount of the active material used is 10% by mass or more, the migration of the binder and the like can be suppressed, and it is also advantageous in terms of the drying cost of the medium. On the other hand, if it is 75 mass% or less, the fluidity and the coatability of the composition can be secured, 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。 Moreover, when preparing the composition for electrode mixture layers in a wet powder state, the amount of active material used is, for example, in the range of 60 to 97% by mass with respect 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, non-volatile components other than active materials such as binders and conductive assistants should be as small as possible within the range in which necessary binding properties and conductivity are ensured.
　非水電解質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 a non-aqueous electrolyte secondary battery electrode mixture layer uses water as a medium. Further, for the purpose of adjusting the properties and drying properties of the composition, lower alcohols such as methanol and ethanol, carbonates such as ethylene carbonate, ketones such as acetone, water soluble organic solvents such as tetrahydrofuran, N-methylpyrrolidone and the like It may be a mixed solvent with The proportion 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 making the composition for electrode mixture layers into a slurry state that can be applied, the content of the medium containing water occupied in the whole composition is the coating property of the slurry, the energy cost required for drying, the viewpoint of productivity For example, it can be in the range of 25 to 90% by mass, and can be, for example, 35 to 70% by mass. In the case of a wettable powder state, the content of the above-mentioned medium can be, for example, in the range of 3 to 40% by mass from the viewpoint of the uniformity of the mixture layer after pressing. It can be in the range of ̃30% by mass.
　本発明のバインダーは、上記架橋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 invention may consist only of the above-mentioned crosslinked polymer or a salt thereof, but other than this, it is possible to use other materials such as styrene / butadiene latex (SBR), acrylic latex and polyvinylidene fluoride latex. You may use a binder component together. When other binder components are used in combination, the amount used can be, for example, 0.1 to 5% by mass or less, and for example, 0.1 to 2% by mass or less, with respect to the active material. And, for example, 0.1 to 1% by mass or less. If the amount of the other binder component used exceeds 5% by mass, the resistance may increase and the high rate characteristics may be insufficient. Among the above, the styrene / butadiene latex is preferable in that it is excellent in the balance between the binding property and the 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. 1 shows an aqueous dispersion. As the above-mentioned aromatic vinyl monomer, in addition to styrene, α-methylstyrene, vinyltoluene, divinylbenzene and the like can be mentioned, and one or more of these can be used. The structural unit derived from the above-mentioned aromatic vinyl monomer in the above-mentioned copolymer can be, for example, in the range of 20 to 60% by mass, mainly from the viewpoint of binding property, and also, for example, 30 to 50 It can be in the range of 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。 As the above-mentioned aliphatic conjugated diene type monomer, in addition to 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene Butadiene etc. are mentioned and 1 type, or 2 or more types in 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 binding property of the binder and the flexibility of the obtained electrode are good. And, for example, 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, styrene / butadiene-based latex may contain a nitrile group-containing monomer such as (meth) acrylonitrile as the other monomer in order to further improve the performance such as binding property. ) A carboxyl group-containing monomer such as acrylic acid, itaconic acid or maleic acid may be used as a copolymer 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 also be in the range of 0 to 20% by mass, for example.
　本発明の非水電解質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架橋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 non-aqueous electrolyte secondary battery electrode mixture layer of the present invention contains the above-mentioned active material, water and a binder as essential components, and is prepared by mixing the components using a known means. can get. The mixing method of each component is not particularly limited, and a known method can be adopted, but after dry blending of powder components such as active material, conductive additive and crosslinked polymer particles as binder, water is used. The method of mixing with a dispersion medium such as, etc., and dispersing and kneading is preferable. When obtaining the composition for electrode mixture layers in a slurry state, it is preferable to finish it in the slurry which does not have poor dispersion and 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 in that a good dispersion state can be obtained in a short time. Is preferred. Moreover, when using a thin film revolving mixer, it is preferable to perform preliminary dispersion beforehand with a stirrer such as a disper. The viscosity of the above-mentioned 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 composition for the electrode mixture layer is obtained in a wet powder state, it is preferable to knead it to a uniform state without concentration unevenness using a Henschel mixer, a blender, a planetary mixer, a twin-screw kneader or the like.
　また、非水電解質二次電池電極合剤層用組成物中に多量の多価金属イオンが含まれると、架橋重合体のカルボキシル基と相互作用する結果、スラリーの安定性が低下し、電極合剤層の均一性及び結着性が低下する恐れがある。係る観点から、非水電解質二次電池電極合剤層用組成物中の多価金属イオン濃度は、架橋重合体に対して好ましくは１００ｐｐｍ以下であり、より好ましくは５０ｐｐｍ以下であり、さらに好ましくは１０ｐｐｍ以下である。多価金属としては特に限定されないが、例えば、Ｆｅ、Ａｌ、Ｃｒ、Ｃｕ、Ｃａ等が挙げられる。 In addition, when a large amount of polyvalent metal ions are contained in the composition for a non-aqueous electrolyte secondary battery electrode mixture layer, as a result of interaction with the carboxyl group of the cross-linked polymer, the stability of the slurry decreases and the electrode assembly The uniformity and binding of the agent layer may be reduced. From such a viewpoint, the concentration of polyvalent metal ions in the composition for a non-aqueous electrolyte secondary battery electrode mixture layer is preferably 100 ppm or less, more preferably 50 ppm or less, more preferably 50 ppm or less, based on the crosslinked polymer. It is 10 ppm or less. The polyvalent metal is not particularly limited, and examples thereof include Fe, Al, Cr, Cu, Ca and the like.
＜非水電解質二次電池用電極＞
　本発明の非水電解質二次電池用電極は、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、集電体の表面に本発明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 non-aqueous electrolyte secondary battery>
The electrode for a non-aqueous electrolyte secondary battery of the present invention comprises a mixture layer formed of the composition for an electrode mixture layer on the surface of a current collector such as copper or aluminum. The mixture layer is formed by applying the composition for electrode mixture layer of the present invention to the surface of the current collector and then drying and removing a medium such as water. 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 coating method, a comma coating method, a curtain coating method, a gravure coating method or an extrusion method is employed. be able to. Moreover, the said drying can be performed by well-known methods, such as a warm air blowing, 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 compression, the active material and the binder can be adhered, and the strength of the mixture layer and the adhesion to the current collector can be improved. The thickness of the mixture layer can be adjusted to, for example, about 30 to 80% before compression by compression, and the thickness of the mixture layer after compression is generally about 4 to 200 μm.
　本発明の非水電解質二次電池用電極にセパレータ及び非水電解液を備えることにより、非水電解質二次電池を作製することができる。
　セパレータは電池の正極及び負極間に配され、両極の接触による短絡の防止や電解液を保持してイオン導電性を確保する役割を担う。セパレータにはフィルム状の絶縁性微多孔膜であって、良好なイオン透過性及び機械的強度を有するものが好ましい。具体的な素材としては、ポリエチレン及びポリプロピレン等のポリオレフィン、ポリテトラフルオロエチレン等を使用することができる。 A non-aqueous electrolyte secondary battery can be produced by providing the electrode for a non-aqueous electrolyte secondary battery of the present invention with a separator and a non-aqueous electrolyte.
The separator is disposed between the positive electrode and the negative electrode of the battery, and plays a role of preventing short circuit due to the contact of both electrodes and maintaining the electrolytic solution to secure the ion conductivity. The separator is preferably a film-like insulating microporous membrane having good ion permeability and mechanical strength. As specific materials, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene and the like can be used.
　非水電解液は、非水電解質二次電池に一般的に使用される公知のものを用いることができる。具体的な溶媒としては、プロピレンカーボネート及びエチレンカーボネート等の高誘電率で電解質の溶解能力の高い環状カーボネート、並びに、エチルメチルカーボネート、ジメチルカーボネート及びジエチルカーボネート等の粘性の低い鎖状カーボネート等が挙げられ、これらを単独で又は混合溶媒として使用することができる。非水電解液は、これらの溶媒にＬｉＰＦ6、ＬｉＳｂＦ6、ＬｉＢＦ4、ＬｉＣｌＯ4、ＬｉＡｌＯ4等のリチウム塩を溶解して使用される。非水電解質二次電池は、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。 The non-aqueous electrolyte can be a known one commonly used in non-aqueous electrolyte secondary batteries. Specific examples of the solvent include cyclic carbonates having a high dielectric constant such as propylene carbonate and ethylene carbonate and having a high ability to dissolve the electrolyte, and low viscosity linear carbonates such as ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate. These can be used alone or as a mixed solvent. The non-aqueous electrolytic solution is used by dissolving a lithium salt such as LiPF 6 , LiSbF 6 , LiBF 4 , LiClO 4 , LiAlO 4 or the like in these solvents. A non-aqueous electrolyte secondary battery is obtained by accommodating the positive electrode plate and the negative electrode plate separated by the separator in a spiral or laminated structure in a case or the like.
　以上説明したように、本明細書に開示される非水電解質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非水電解質二次電池は、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。 As described above, the binder for a non-aqueous electrolyte secondary battery electrode disclosed in the present specification exhibits excellent binding property with the electrode material and excellent adhesion property with the current collector in the mixture layer. For this reason, the non-aqueous electrolyte secondary battery provided with the electrode obtained by using the above-mentioned binder can ensure good integrity, and is expected to exhibit good durability (cycle characteristics) even if charge and discharge are repeated. And suitable for use in on-vehicle secondary batteries and the like.
　以下、実施例に基づいて本発明を具体的に説明する。尚、本発明は、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 invention will be specifically described based on examples. The present invention is not limited by these examples. In the following, “parts” and “%” mean parts by mass and% by mass unless otherwise specified.
≪架橋重合体塩の製造≫
（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、ペンタエリスリトールトリアリルエーテル（ダイソー社製、商品名「ネオアリルＰ－３０」）０．６０部及び上記ＡＡに対して１．０モル％に相当するトリオク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、反応開始点から１２時間経過した時点で反応液の冷却を開始し、内温が２５℃まで低下した後、水酸化リチウム・一水和物（以下、「ＬｉＯＨ・Ｈ2Ｏ」という）の粉末５２．５部を添加した。添加後室温下１２時間撹拌を継続して、架橋重合体塩Ｒ－１（Ｌｉ塩、中和度９０モル％）の粒子が媒体に分散したスラリー状の重合反応液を得た。 << Production of Crosslinked Polymer Salts >>
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 inlet was used.
In a reactor, 567 parts of acetonitrile, 2.20 parts of ion exchange water, 100 parts of acrylic acid (hereinafter referred to as "AA"), pentaerythritol triallyl ether (trade name "Neoallyl P-30" manufactured by Daiso Corporation) 0. 60 parts and trioctylamine corresponding to 1.0 mol% with respect to the above AA were charged. The inside of the reactor was sufficiently purged with nitrogen, and then warmed to raise the internal temperature to 55 ° C. After confirming that the internal temperature was stabilized at 55 ° C., 2, 2′-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, trade name “V-65”) 0 as a polymerization initiator When 040 parts were added, white turbidity was observed in the reaction solution, and this point was regarded as the polymerization initiation point. The monomer concentration was calculated to be 15.0%. The polymerization reaction was continued while maintaining the internal temperature at 55 ° C. by adjusting the external temperature (water bath temperature), and the internal temperature was raised to 65 ° C. after 6 hours from the polymerization initiation point. The internal temperature is maintained at 65 ° C., and cooling of the reaction solution is started 12 hours after the reaction start point, and after the internal temperature drops to 25 ° C. lithium hydroxide monohydrate (hereinafter referred to as “LiOH” • 52.5 parts of powder of H 2 O ”) were added. After the addition, stirring was continued at room temperature for 12 hours to obtain a slurry-like polymerization reaction solution in which particles of a crosslinked polymer salt R-1 (Li salt, neutralization degree 90 mol%) were dispersed in a medium.
（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０．３５μｍであった。 (Measurement of average particle size before swelling of crosslinked polymer salt R-1 (Li neutralized product))
The particle size of the polymerization reaction solution containing the crosslinked polymer salt R-1 obtained above is measured using a laser diffraction / scattering type particle size distribution analyzer (Microtrac MT-3300EXII manufactured by Microtrac Bell Co., Ltd.) using acetonitrile as a dispersion medium. It measured. The volume based median diameter was 0.35 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、架橋重合体塩Ｒ－１の粉末を得た。架橋重合体塩Ｒ－１は吸湿性を有するため、水蒸気バリア性を有する容器に密封保管した。なお、架橋重合体塩Ｒ－１の粉末をＩＲ測定し、カルボン酸のＣ＝Ｏ基由来のピークとカルボン酸ＬｉのＣ＝Ｏ由来のピークの強度比より中和度を求めたところ、仕込みからの計算値に等しく９０モル％であった。 The resulting polymerization reaction solution was centrifuged to precipitate polymer particles, and then the supernatant was removed. Thereafter, the precipitate was re-dispersed in acetonitrile having the same weight as that of the polymerization reaction solution, and then the washing operation of settling polymer particles by centrifugation and removing the supernatant was repeated twice. The precipitate was collected, dried at 80 ° C. for 3 hours under reduced pressure conditions, and volatile components were removed to obtain a powder of a crosslinked polymer salt R-1. Since the crosslinked polymer salt R-1 has hygroscopicity, it was sealed and stored in a container having water vapor barrier properties. The degree of neutralization of the powder of the crosslinked polymer salt R-1 was determined by IR measurement, and the degree of neutralization was determined from the ratio of the peak derived from the C = O group of the carboxylic acid and the peak derived from C = O of the carboxylic acid Li. The calculated value from was equal to 90 mol%.
（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、１．２μｍ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１．２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 size of crosslinked polymer salt R-1 (Li neutralized product) in aqueous medium)
0.25 g of the powder of the crosslinked polymer salt R-1 obtained above and 49.75 g of ion-exchanged water are weighed in a 100 cc container, and a rotation / revolution stirrer (manufactured by Shinky Co., Ltd., Awatori Urutaro AR-250) Set to). Then, stirring (rotation speed 2000 rpm / rotation speed 800 rpm, 7 minutes), and defoaming (rotation speed 2200 rpm / rotation speed 60 rpm, 1 minute), the crosslinked polymer salt R-1 (degree of neutralization 90 mol%) A hydrogel swelled in water was prepared.
Next, the particle size distribution of the hydrogel was measured with a laser diffraction / scattering particle size distribution analyzer (Microtrac MT-3300EXII, manufactured by Microtrac Bell, Inc.) using ion exchange water as a dispersion medium. When an amount of hydrogel capable of obtaining an appropriate amount of scattered light intensity was added to a portion of the hydrogel circulating an excessive amount of dispersion medium, the particle size distribution shape measured after several minutes became stable. As soon as the stability was confirmed, volume-based particle size distribution measurement was performed, and a median diameter (D50) was determined as an average particle diameter, which was 1.2 μm. Moreover, as a result of evaluating monodispersion according to the following reference | standard, the particle size distribution represented by (volume based median diameter / number based median diameter) is 1.2, and monodispersity was judged as "(double-circle)" .
Evaluation criteria;
:: volume-based median diameter / number-based median diameter less than 1.5 ○: volume-based median diameter / number-based median diameter 1.5 or more and less than 3.0 Δ: volume-based median diameter / number-based median diameter 3 .0 or more and less than 10 ×: Volume based median diameter / number based median diameter is 10 or more
（製造例２～２２：架橋重合体（塩）Ｒ－２～Ｒ－２２の製造）
　各原料の仕込み量を表１又は表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－２２を含む重合反応液を得た。各重合反応液について製造例１と同様の操作により膨潤前平均粒子径を測定し、表１及び表２に示した。
　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－２２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。
　得られた各重合体（塩）について、製造例１と同様に、水媒体中での平均粒子径を測定した。結果を表１又は表２に示す。尚、製造例１９では、ＬｉＯＨ・Ｈ2Ｏの粉末５２．５部の代わりにＮａＯＨを用いることにより。架橋重合体Ｎａ塩（中和度９０モル％）を得た。 (Production Examples 2 to 22: Production of Cross-Linked Polymer (Salt) R-2 to R-22)
A polymerization reaction liquid containing crosslinked polymers (salts) R-2 to R-22 was obtained in the same manner as in Production Example 1 except that the preparation amounts of the respective raw materials were as described in Table 1 or Table 2. . The average particle size before swelling of each of the polymerization reaction solutions was measured in the same manner as in Production Example 1, and the results are shown in Tables 1 and 2.
The same operation as in Production Example 1 was performed for each of the polymerization reaction solutions to obtain powdery crosslinked polymers (salts) R-2 to R-22. Each crosslinked polymer (salt) was sealed and stored in a container having water vapor barrier properties.
About each obtained polymer (salt), the average particle diameter in a water medium was measured like manufacture example 1. The results are shown in Table 1 or Table 2. In Production Example 19, NaOH is used instead of 52.5 parts of LiOH · H 2 O powder. A crosslinked polymer Na salt (degree of neutralization: 90 mol%) was obtained.
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
　ＩＢＸＡ：アクリル酸イソボルニル
　ＤＭＡＡ：Ｎ，Ｎ－ジメチルアクリルアミド
　Ｐ－３０：ペンタエリスリトールトリアリルエーテル（ダイソー社製、商品名「ネオアリルＰ－３０」）
　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」）
　ＴＭＡ：トリメチルアミン（Ｃ／Ｎ値：３）
　ＴＥＡ：トリエチルアミン（Ｃ／Ｎ値：６）
　ＴＯＡ：トリオクチルアミン（Ｃ／Ｎ値：２４）
　ＴＤＡ：トリドデシルアミン（Ｃ／Ｎ値：３６）
　ＴＳＡ：トリステアリルアミン（Ｃ／Ｎ値：５４）
　ピリジン：（Ｃ／Ｎ値：５）
　ジブチルアミン：（Ｃ／Ｎ値：８）
　ヘキシルアミン：（Ｃ／Ｎ値：６）
　ＤＭＡＮ：１，８－ビス（ジメチルアミノ）ナフタレン（Ｃ／Ｎ値：７）
　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）（和光純薬工業社製） Details of the compounds used in Tables 1 and 2 are shown below.
AA: acrylic acid IBXA: isobornyl acrylate DMAA: N, N-dimethyl acrylamide P-30: pentaerythritol triallyl ether (manufactured by Daiso, trade name "Neoallyl P-30")
T-20: trimethylolpropane diallyl ether (made by Daiso, trade name "Neoallyl T-20")
TMA: trimethylamine (C / N value: 3)
TEA: Triethylamine (C / N value: 6)
TOA: Trioctylamine (C / N value: 24)
TDA: tridodecylamine (C / N value: 36)
TSA: tristearylamine (C / N value: 54)
Pyridine: (C / N value: 5)
Dibutylamine: (C / N value: 8)
Hexylamine: (C / N value: 6)
DMAN: 1, 8-bis (dimethylamino) naphthalene (C / N value: 7)
AcN: acetonitrile V-65: 2, 2'-azobis (2,4-dimethyl valeronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)
（負極電極の評価）
　負極活物質として、黒鉛、又は、ケイ素粒子及び黒鉛を用い、各架橋重合体をバインダーとして用いた合剤層用組成物について、その塗工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 negative electrode)
Graphite or silicon particles and graphite as the negative electrode active material, and for the composition for a mixture layer using each crosslinked polymer as a binder, the coatability and between the formed mixture layer / collector Peel strength (ie binder binding) was measured. Natural graphite (trade name "CGB-10" manufactured by Nippon Graphite Co., Ltd.) was used as the graphite, and silicon particles (Sigma-Aldrich, Si nanopowder, particle diameter <100 nm) were used as the 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。
　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５０±５μｍ、充填密度が１．７０±０．２０ｇ／ｃｍ3になるよう圧延した。 Example 1
3.2 parts of powdery crosslinked polymer Li salt R-1 is weighed into 100 parts of natural graphite, mixed well in advance, 160 parts of ion exchanged water is added, predispersion is carried out with a disper, and thin film swirling type This dispersion was carried out for 15 seconds using a mixer (manufactured by Primix, FM-56-30) at a peripheral speed of 20 m / sec to obtain a slurry-like composition for a negative electrode mixture layer.
The composition for the mixture layer is applied on a 20 μm thick copper foil (manufactured by Japan Foil Co., Ltd.) using a variable applicator, and the mixture is dried in a ventilation dryer at 100 ° C. for 15 minutes. A layer was formed. Thereafter, the mixture layer was rolled so as to have a thickness of 50 ± 5 μm and a packing density of 1.70 ± 0.20 g / cm 3 .
　得られた合剤層の外観を目視により観察し、以下の基準に基づいて塗工性を評価した結果、「○」と判断された。
＜塗工性判定基準＞
　○：表面に筋ムラ、ブツ等の外観異常がまったく認められない。
　△：表面に筋ムラ、ブツ等の外観異常がわずかに認められる。
　×：表面に筋ムラ、ブツ等の外観異常が顕著に認められる。 The appearance of the obtained mixture layer was visually observed, and the coatability was evaluated based on the following criteria. As a result, it was determined as "o."
<Coating evaluation criteria>
○: No surface irregularities such as uneven streaks and bumps are observed on the surface.
Fair: slight surface irregularities such as uneven streaks and bumps on the surface.
X: appearance abnormalities such as uneven streaks and bumps are noticeable on the surface.
＜９０°剥離強度（結着性）＞
　上記で得られた負極電極を２５ｍｍ幅の短冊状に裁断した後、水平面に固定された両面テープに上記試料の合剤層面を貼付け、剥離試験用試料を作成した。試験用試料を６０℃、1晩減圧条件下で乾燥させた後、引張速度５０ｍｍ／分における９０°剥離を行い、合剤層と銅箔間の剥離強度を測定した。剥離強度は１５．２Ｎ／ｍと高く、良好であった。 <90 ° peel strength (binding ability)>
The negative electrode obtained above was cut into a strip of 25 mm width, and then the mixture layer surface of the above sample was attached to a double-sided tape fixed on a horizontal surface to prepare a sample for peeling test. After the test sample was dried at 60 ° C. under reduced pressure conditions overnight, 90 ° peeling was performed at a tensile speed of 50 mm / min, and the peel strength between the mixture layer and the copper foil was measured. The peel strength was as high as 15.2 N / m and good.
実施例２～２２、及び比較例１～２
　活物質及びバインダーとして使用する架橋重合体塩を表３又は表４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２及び実施例３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－１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塗工性及び９０°剥離強度を評価した。結果を表３又は表４に示す。 Examples 2 to 22 and Comparative Examples 1 to 2
A mixture layer composition was prepared by performing the same operation as in Example 1 except that the cross-linked polymer salt used as the active material and the binder was used as shown in Table 3 or Table 4. In Examples 2 and 3, natural graphite and silicon particles are stirred at 400 rpm for 1 hour using a planetary ball mill (F-5 made by FRITSCH), and a powdery crosslinked polymer is obtained in the obtained mixture. 3.2 parts of Li salt R-1 was weighed, mixed well in advance, and then the same procedure as in Example 1 was carried out to prepare a mixture layer composition. The coatability and the 90 ° peel strength were evaluated for each mixture layer composition. The results are shown in Table 3 or Table 4.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　各実施例は、本発明に属する非水電解質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（スラリー）の塗工性は良好であり、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。
　実施例１２では、２０％という高い単量体濃度条件下であっても架橋重合体が安定に得られ、当該架橋重合体を含むバインダーは優れた結着性を示した。 In each of the examples, an electrode mixture layer composition containing a binder for a non-aqueous electrolyte secondary battery electrode according to the present invention and an electrode manufactured using the same. The coatability of each mixture layer composition (slurry) is good, and the peel strength between the mixture layer of the obtained electrode and the current collector is a high value in each case, and the binding property is excellent. Was indicated.
In Example 12, a crosslinked polymer was stably obtained even under conditions of a high monomer concentration of 20%, and the binder containing the crosslinked polymer showed excellent binding properties.
　一方、架橋重合体（塩）Ｒ－２１及びＲ－２２は、有機アミン化合物不存在下で重合反応を行った例であり、得られた架橋重合体は高単量体濃度条件下では分散安定性が不十分であり、平均粒子径及び粒子径分布の大きなものであった。また、これらのバインダーとしての評価においても十分な結着性は得られなかった（比較例１及び２）。 On the other hand, the cross-linked polymers (salts) R-21 and R-22 are examples in which the polymerization reaction was carried out in the absence of the organic amine compound, and the obtained cross-linked polymer was stable under high monomer concentration conditions. The properties were insufficient, and the average particle size and the particle size distribution were large. Further, even in the evaluation as these binders, sufficient binding properties were not obtained (Comparative Examples 1 and 2).
　本発明の非水電解質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非水電解質二次電池は、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。 The binder for a non-aqueous electrolyte secondary battery electrode of the present invention exhibits excellent binding ability in the mixture layer, and therefore, a non-aqueous electrolyte secondary battery provided with an electrode obtained using the above-mentioned binder is excellent. It is expected to exhibit good durability (cycle characteristics), and is expected to be applied to automotive secondary batteries. Moreover, it is useful also for use of the active material containing a silicon | silicone, and the contribution to the high capacitation of a battery is anticipated.

Claims (8)

  1. 　架橋重合体又はその塩を含有する非水電解質二次電池電極用バインダーであって、
    　前記架橋重合体は、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を含み、有機アミン化合物存在下、単量体成分を重合して得られたものである、非水電解質二次電池電極用バインダー。     It is a binder for nonaqueous electrolyte secondary battery electrodes containing a crosslinked polymer or a salt thereof,
    The non-aqueous electrolyte secondary battery, wherein the crosslinked polymer comprises a structural unit derived from an ethylenically unsaturated carboxylic acid monomer, and is obtained by polymerizing a monomer component in the presence of an organic amine compound. Binder for electrodes.
  2. 　前記有機アミン化合物は、当該有機アミン化合物に存在する窒素原子数に対する炭素原子数の比で表される値（Ｃ／Ｎ）が３以上である請求項１に記載の非水電解質二次電池電極用バインダー。 The non-aqueous electrolyte secondary battery electrode according to claim 1, wherein the organic amine compound has a value (C / N) represented by a ratio of the number of carbon atoms to the number of nitrogen atoms present in the organic amine compound. Binder.
  3. 　前記架橋重合体の重合に用いる単量体の総量に対する前記エチレン性不飽和カルボン酸単量体の濃度が、１０質量％以上、１００質量％以下である請求項１又は２に記載の非水電解質二次電池電極用バインダー。 The non-aqueous electrolyte according to claim 1 or 2, wherein the concentration of the ethylenically unsaturated carboxylic acid monomer is 10% by mass or more and 100% by mass or less based on the total amount of the monomers used for the polymerization of the crosslinked polymer. Binder for secondary battery electrodes.
  4. 　前記エチレン性不飽和カルボン酸単量体に対する前記有機アミン化合物の使用量が、０．００１モル％以上、４．０モル％以下である請求項１～３のいずれか１項に記載の非水電解質二次電池電極用バインダー。 The non-water according to any one of claims 1 to 3, wherein the amount of the organic amine compound used relative to the ethylenically unsaturated carboxylic acid monomer is 0.001 mol% or more and 4.0 mol% or less. Binder for electrolyte secondary battery electrode.
  5. 　非水電解質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、
    　有機アミン化合物存在下、エチレン性不飽和カルボン酸単量体を含む単量体成分を沈殿重合法により重合する重合工程を備える、方法。     A method for producing a crosslinked polymer or a salt thereof for use in a binder for non-aqueous electrolyte secondary battery electrodes, comprising:
    A method comprising a polymerization step of polymerizing a monomer component containing an ethylenically unsaturated carboxylic acid monomer by a precipitation polymerization method in the presence of an organic amine compound.
  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非水電解質二次電池電極合剤層用組成物。 A composition for a non-aqueous electrolyte 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に記載の非水電解質二次電池電極合剤層用組成物。 The composition for a non-aqueous electrolyte secondary battery electrode mixture layer according to claim 6, which contains 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に記載の非水電解質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非水電解質二次電池電極。 The nonaqueous electrolyte secondary battery electrode provided with the mixture layer formed from the composition for nonaqueous electrolyte secondary battery electrode mixture layers of Claim 6 or 7 on the surface of a collector.
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