WO2022138322A1 - Separator binder for nonaqueous secondary battery, separator for nonaqueous secondary battery, method for producing separator slurry for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Separator binder for nonaqueous secondary battery, separator for nonaqueous secondary battery, method for producing separator slurry for nonaqueous secondary battery, and nonaqueous secondary battery Download PDF

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Publication number
WO2022138322A1
WO2022138322A1 PCT/JP2021/046014 JP2021046014W WO2022138322A1 WO 2022138322 A1 WO2022138322 A1 WO 2022138322A1 JP 2021046014 W JP2021046014 W JP 2021046014W WO 2022138322 A1 WO2022138322 A1 WO 2022138322A1
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Prior art keywords
polymer
separator
secondary battery
aqueous secondary
structural unit
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PCT/JP2021/046014
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French (fr)
Japanese (ja)
Inventor
健太郎 高橋
充 花▲崎▼
智規 倉田
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昭和電工株式会社
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Priority to JP2022572189A priority Critical patent/JPWO2022138322A1/ja
Priority to KR1020237020006A priority patent/KR20230124572A/en
Priority to CN202180084547.2A priority patent/CN116601193A/en
Publication of WO2022138322A1 publication Critical patent/WO2022138322A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/52—Amides or imides
    • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
    • C08F220/56—Acrylamide; Methacrylamide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
    • C08K3/013—Fillers, pigments or reinforcing additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
    • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
    • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/24—Homopolymers or copolymers of amides or imides
    • C08L33/26—Homopolymers or copolymers of acrylamide or methacrylamide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a separator binder for a non-aqueous secondary battery, a separator for a non-aqueous secondary battery, a method for producing a separator slurry for a non-aqueous secondary battery, and a non-aqueous secondary battery.
  • a lithium ion secondary battery is a secondary battery in which lithium ions move between a positive electrode and a negative electrode to charge and discharge the battery.
  • the main components of the lithium ion secondary battery are a positive electrode in which a positive electrode active material layer containing a metal oxide such as lithium cobaltate is formed on the surface of a current collector such as aluminum, and graphite or the like on the surface of the current collector such as copper. It contains a negative electrode on which a negative electrode active material layer containing the above-mentioned material is formed, a separator provided between the positive electrode and the negative electrode, and an electrolytic solution in which an electrolyte such as a lithium salt is dissolved in a solvent such as carbonate.
  • the separator is a member provided to isolate between the positive electrode and the negative electrode, and a base material such as a resin porous membrane is widely used as a separator in non-aqueous secondary batteries.
  • a base material such as a resin porous membrane is widely used as a separator in non-aqueous secondary batteries.
  • the holes in the separator are closed, preventing the movement of carrier ions and shutting down the battery.
  • the energy density of secondary batteries has been increasing, and the amount of heat generated by the batteries during use tends to increase. Therefore, in order to impart heat resistance to the separator, it has been proposed to form a coating layer containing a binder and non-conductive particles on at least one surface of the base material.
  • the coating layer generally contains organic or inorganic particles (fillers) and a binder for fixing the particles on the surface of the substrate.
  • Patent Document 1 describes applying a mixture containing alumina staple fibers, polyvinylidene fluoride, and N-methylpyrrolidone to a porous polypropylene sheet.
  • Patent Document 2 describes a separator for a non-aqueous electrolytic solution secondary battery in which a porous membrane of a water-soluble polymer and a porous membrane of a polyolefin are laminated, and examples of the water-soluble polymer include polyvinyl alcohol and carboxymethyl cellulose (CMC). Is described. In the examples, it is described that a slurry containing CMC and alumina fine particles is applied onto a porous film to prepare a separator.
  • CMC carboxymethyl cellulose
  • Patent Document 3 describes a multilayer porous membrane provided with a porous layer composed of an inorganic filler and polyvinyl alcohol having a saponification degree of 85% or more on at least one surface of the polyolefin resin porous membrane.
  • Patent Document 4 describes a resin composition for a binder containing a water-soluble polymer having a metal carboxylate group and a water-soluble polymer having a hydroxyl group, a carboxy group or a sulfo group, as a separator for a non-aqueous electrolyte secondary battery. It is described that it is used to bind filler particles to the surface of a substrate. Examples describe an example in which carboxymethyl cellulose and polyvinyl alcohol are used in combination as a binder and water is used as a solvent.
  • Japanese Patent No. 3756815 Japanese Unexamined Patent Publication No. 2004-227972 Japanese Unexamined Patent Publication No. 2008-186721 International Publication No. 2013/154197
  • the CMC resin is inferior in dispersibility of the inorganic filler, tends to be a highly viscous slurry, and tends to deteriorate in coatability. Further, the slurry using them is inferior in wettability to the polyolefin porous film. The heat resistance of the obtained separator is also insufficient. Further, since the layer obtained by drying the slurry is inferior in adhesion to the polyolefin porous film, the produced laminated porous separator is liable to cause powder falling off.
  • Patent Document 3 the dimensional stability of the porous layer at high temperature is insufficient.
  • the slurry containing the CMC resin has a high viscosity and is inferior in coatability.
  • the present invention it is possible to produce a slurry having good wettability to a substrate and good coatability, it is possible to form a coating layer having high peel strength on a separator, and it is possible to suppress thermal shrinkage of the separator. It is an object of the present invention to provide a separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery. Another object of the present invention is to provide a separator for a non-aqueous secondary battery, which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.
  • the polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
  • the value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. It is /5.0 or less, and the value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) is 55.0 / 45.0 or more and 97.0 / 3.0.
  • the following separator binder for non-aqueous secondary batteries [2] The separator binder for a non-aqueous secondary battery according to [1], which comprises only the polymer (A) and the polymer (B).
  • the total content of the first structural unit (a1) and the second structural unit (a2) in the polymer (A) is 80% by mass or more, any of [1] to [5].
  • the above-mentioned separator binder for non-aqueous secondary batteries [7] The non-aqueous secondary battery according to any one of [1] to [6], wherein the polymer (A) comprises only the first structural unit (a1) and the second structural unit (a2).
  • a separator binder composition for a non-aqueous secondary battery which comprises the separator binder for a non-aqueous secondary battery according to any one of [1] to [11] and an aqueous medium.
  • a separator slurry for a non-aqueous secondary battery which comprises the separator binder for a non-aqueous secondary battery according to any one of [1] to [11], a filler, and an aqueous medium.
  • a separator for a non-aqueous secondary battery comprising a substrate which is a porous film and a coating layer formed on the surface of the substrate.
  • the coating layer is a separator for a non-aqueous secondary battery containing the separator binder for a non-aqueous secondary battery according to any one of [1] to [11] and a filler.
  • the value of the mass ratio of the content of the separator binder for a non-aqueous secondary battery and the content of the filler in the coating layer is 1.0 / 99.0 or more and 15.0 / 85.0 or less.
  • the separator for a non-aqueous secondary battery according to [14].
  • the first step of mixing the polymer (A) and the filler in an aqueous medium, and A second step of adding and mixing the polymer (B) to the mixture obtained in the first step is included.
  • the polymer (A) is a polymer of a compound having an ethylenically unsaturated bond, and is derived from a first structural unit (a1) derived from (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond.
  • the polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
  • the value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. /5.0 or less
  • the value of the mass ratio of the amount of the polymer (A) used and the amount of the polymer (B) used is 55.0 / 45.0 or more and 97.0 / 3.0 or less, which is a non-aqueous secondary battery.
  • Method for manufacturing separator slurry [17] A non-aqueous secondary battery comprising the separator for a non-aqueous secondary battery according to [14] or [15].
  • a separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery can be provided. Further, according to the present invention, it is possible to provide a separator for a non-aqueous secondary battery, which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.
  • a separator binder for a non-aqueous secondary battery also referred to as a binder for a non-aqueous secondary battery separator
  • a separator binder composition for a non-aqueous secondary battery binder composition for a non-aqueous secondary battery separator
  • a separator slurry for a non-aqueous secondary battery also referred to as a slurry for a non-aqueous secondary battery separator
  • the separator binder for a non-aqueous secondary battery is a binder for applying to a separator for a non-aqueous secondary battery
  • the separator binder composition for a non-aqueous secondary battery is a non-aqueous secondary battery. It is a binder composition for application to a separator for a secondary battery
  • the separator slurry for a non-aqueous secondary battery is a separator slurry for application to a separator for a non-aqueous secondary battery.
  • (Meta) acrylic is a general term for acrylic and methacrylic
  • (meth) acrylate is a general term for acrylate and methacrylate.
  • the “nonvolatile component” is a component remaining after weighing 1 g of the composition in an aluminum dish having a diameter of 5 cm and drying at 130 ° C. for 1 hour while circulating air in a dryer at 1 atm (1013 hPa).
  • the form of the composition includes, but is not limited to, a solution, a dispersion, and a slurry.
  • the “nonvolatile content concentration” is the mass ratio (mass%) of the non-volatile content after drying under the above conditions with respect to the mass (1 g) of the composition before drying.
  • Ethylene unsaturated bond refers to an ethylenically unsaturated bond having radical polymerization unless otherwise specified.
  • the "hydroxyl group” does not include OH bonded to an atom other than carbon, OH possessed by an anionic functional group such as a carboxy group, and OH bonded to a carbon atom forming an aromatic ring.
  • the structural unit derived from the compound having a certain ethylenically unsaturated bond is the chemical structure of the portion other than the ethylenically unsaturated bond of the compound and its structure in the polymer. It is assumed that the chemical structure of the part other than the part forming the main chain of the unit is the same.
  • the structural unit derived from acrylamide has a structure of CONH 2 in a portion other than the main chain as a polymer.
  • the chemical structure of the monomer does not correspond to the chemical structure of the polymer, such as the chemical reaction of parts other than the main chain after polymerization
  • the chemical structure after polymerization is used as the standard.
  • the saponified structural unit is a structural unit derived from vinyl alcohol in consideration of the chemical structure of the polymer.
  • polyvinyl alcohol (PVA) obtained by saponifying polyvinyl acetate is a copolymer containing a structural unit derived from vinyl acetate and a structural unit derived from vinyl alcohol when the degree of saponification is not 100 mol%. Will be.
  • the anionic functional group is a functional group that releases cations (hydrogen ion, metal ion, ammonium ion, etc.) when dissolved in water having a pH of 7.0.
  • examples of the anionic functional group include a carboxy group, a sulfo group, a phosphoric acid group, a phenolic hydroxyl group and the like.
  • the surface means "hail noodles”.
  • the separator binder for a non-aqueous secondary battery according to an embodiment of the present invention includes a polymer (A) and a polymer (B).
  • the separator binder for a non-aqueous secondary battery according to an embodiment of the present invention is preferably composed of only the polymer (A) and the polymer (B). Each of the polymer (A) and the polymer (B) will be described below.
  • the polymer (A) is a polymer of a compound having an ethylenically unsaturated bond.
  • the polymer (A) is a copolymer containing a first structural unit (a1) derived from (meth) acrylamide and a second structural unit (a2) derived from a compound having a hydroxyl group and an ethylenically unsaturated bond. be.
  • the polymer (A) preferably does not have an anionic functional group.
  • the solubility of the polymer (A) in 100 g of water is preferably 2.0 g / 100 g or more, more preferably 5.0 g / 100 g or more, and further preferably 10.0 g / 100 g or more. ..
  • the first structural unit (a1) is a structural unit derived from (meth) acrylamide, and examples of the (meth) acrylamide for the first structural unit (a1) include acrylamide, methacrylamide, and mixtures thereof. Be done.
  • the second structural unit (a2) is a structural unit derived from a compound having a hydroxyl group and an ethylenically unsaturated bond, and is a structural unit containing a hydroxyl group.
  • a compound having only one hydroxyl group is preferable.
  • a structural unit derived from (meth) acrylate having a hydroxyl group or vinyl alcohol can be considered.
  • the second structural unit (a2) is preferably a structural unit derived from a (meth) acrylate having a hydroxyl group, and is an alkyl (meth) acrylate in which any hydrogen atom of an alkyl group is substituted with a hydroxyl group. More preferred.
  • Examples of (meth) acrylates having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, and hydroxyhexyl (meth) acrylate. , Hydroxyoctyl (meth) acrylate, pentaerythritol tri, di or mono (meth) acrylate, trimethylolpropane di or hydroxyalkyl (meth) acrylate such as mono (meth) acrylate and the like.
  • the second structural unit (a2) is more preferably a structural unit derived from 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate, and 2-. It is more preferably hydroxyethyl (meth) acrylate.
  • 2-hydroxyethyl methacrylate is particularly preferable from the viewpoint of improving peel strength and reducing heat shrinkage. The reason why 2-hydroxyethyl methacrylate is particularly effective is not clear, but it is presumed to be due to the synergistic effect with (meth) acrylamide for the first structural unit (a1).
  • the polymerizable property with (meth) acrylamide is different between 2-hydroxyethyl methacrylate and other compounds such as 2-hydroxyethyl acrylate.
  • 2-hydroxyethyl methacrylate has a non-uniform composition ratio of the polymer, and a part of the polymer causes microphase separation, so that the peel strength at a more suitable level is used. It is considered that the improvement of the heat shrinkage and the reduction of heat shrinkage are realized.
  • the value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is It is 55.0 / 45.0 or more, preferably 65.0 / 35.0 or more, and more preferably 75.0 / 25.0 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved.
  • the value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is , 95.0 / 5.0 or less, more preferably 90.0 / 10.0 or less, and even more preferably 85.0 / 15.0 or less. This is to improve the compatibility between the polymer (A) and the polymer (B), suppress the increase in the viscosity of the slurry described later, and improve the coatability.
  • the polymer (A) may contain structural units derived from other compounds, but the first structural unit (a1) and the second structural unit (a1) and the second structural unit (a1) among all the structural units in the polymer (A).
  • the total content of a2) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, it is particularly preferable that the polymer (A) is a copolymer composed of only the first structural unit (a1) and the second structural unit (a2). This is because the effect of the polymer (A), which is the object of the present invention, is further enhanced.
  • the structural unit in the polymer (A1) does not include a structure derived from a polymerization initiator, a terminator, a chain transfer agent, or the like used in the production process.
  • the polymer (A) or the separator binder composition for a non-aqueous secondary battery described later does not contain a heat-crosslinkable constituent component (heat-crosslinkable structural unit or heat-crosslinkable compound). This is to suppress a decrease in dispersibility due to a decrease in the wettability of the polymer with respect to the filler when the polymer (A) is applied to a separator slurry for a non-aqueous secondary battery described later.
  • a heat-crosslinkable constituent component heat-crosslinkable structural unit or heat-crosslinkable compound
  • the polymer (A) when applied to a separator for a non-aqueous secondary battery, it suppresses a change in the size of the separator due to curing shrinkage of the polymer in the coating layer and a decrease in the peel strength of the coating layer with respect to the substrate. Because.
  • the heat-crosslinkable constituent component according to the present embodiment contains a heat-crosslinkable structural unit or a heat-crosslinkable compound.
  • the heat-crosslinkable structural unit include a structural unit derived from a monomer having an epoxy group, a structural unit derived from another functional (meth) acrylate, and the like. Examples of the monomer from which these structural units are derived include glycidyl methacrylate and ethylene glycol dimethacrylate.
  • the heat-crosslinkable compound include compounds used as a cross-linking agent, and examples thereof include carbodiimide compounds, epoxy compounds, and isocyanate compounds.
  • the weight average molecular weight of the polymer (A) is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 350,000 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the electrolytic solution resistance, strength, and peel strength of the coating layer with respect to the substrate are improved.
  • the weight average molecular weight of the polymer (A) is preferably 3,000,000 or less, more preferably 1,500,000 or less, and even more preferably 650,000 or less. This is because it suppresses an increase in the viscosity of the slurry, which will be described later, and improves the coatability of the slurry on the substrate.
  • the weight average molecular weight is a pullulan-equivalent value measured using gel permeation chromatography (GPC).
  • Examples of the method for synthesizing the polymer (A) include aqueous solution polymerization of a monomer containing (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond.
  • Examples of the radical polymerization initiator used in the synthesis include, but are not limited to, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and azo compounds.
  • Examples of the azo compound include 2,2'-azobis (2-methylpropionamidine) dihydrochloride.
  • a radical polymerization initiator and a reducing agent may be used in combination at the time of polymerization for redox polymerization.
  • the reducing agent include sodium bisulfite, longalit, ascorbic acid and the like.
  • the polymer (B) is polyvinyl alcohol (PVA).
  • the degree of saponification of the polymer (B) is 55 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved.
  • the saponification degree is a value measured by the measuring method according to JIS K6726 (1994) 3.5 (the simple method is not used).
  • the degree of saponification of the polymer (B) may be 100 mol%, but is preferably 99 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less. This is to ensure the compatibility between the polymer (B) and the polymer (A), suppress the increase in the viscosity of the slurry described later, and improve the coatability on the substrate.
  • the degree of polymerization of the polymer (B) is preferably 100 or more, more preferably 300 or more, further preferably 1000 or more, still more preferably 1500 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved.
  • the degree of polymerization is a value measured by the measuring method according to JIS K6726 (1994) 3.7.
  • the degree of polymerization of the polymer (B) is preferably 5000 or less, more preferably 4000 or less, and even more preferably 3000 or less. This is to suppress an increase in the viscosity of the slurry, which will be described later, and to improve the coatability on the substrate.
  • the value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) in the separator binder for a non-aqueous secondary battery is 97.0 / 3.0 or less, and 93.0 / 7 It is preferably 0.0 or less, and more preferably 85.0 / 15.0 or less. This is because when the porous organic film is used as the base material, the wettability of the slurry to the base material is improved. Further, when the binder is applied to the separator for a non-aqueous secondary battery, the peel strength of the coating layer with respect to the substrate is improved.
  • the separator binder composition for a non-aqueous secondary battery according to the present embodiment includes the above-mentioned separator binder for a non-aqueous secondary battery and an aqueous medium.
  • a separator binder composition for a non-aqueous secondary battery may be used as a binder composition.
  • the binder composition it is preferable that both the polymer (A) and the polymer (B) are dissolved in an aqueous medium.
  • the binder composition according to the present embodiment may contain components derived from the components used for producing the binder, and polymers other than the polymers contained in the binder of the present invention. It may contain various additives and the like.
  • the organic solvent preferably has a boiling point at atmospheric pressure of 50 to 150 ° C.
  • organic solvent compatible with water examples include alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol; saturated aliphatic ether compounds such as dipropyl ether, diisopropyl ether, dibutyl ether and diisobutyl ether; tetrahydrofuran, Cyclic ether compounds such as tetrahydropyran and dioxane; organic acid ester compounds such as butyl formate, amyl formate, ethyl acetate, propyl acetate, isopropyl acetate and butyl acetate; ketone compounds such as acetone, ethyl ketone and cyclohexanone can be mentioned.
  • alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol
  • saturated aliphatic ether compounds such as dipropyl ether, diisopropyl ether, dibutyl ether and diisobut
  • the content of the organic solvent with respect to 100 parts by mass of water is not particularly limited, but is preferably 100 parts by mass or less, and is preferably 20 parts by mass or less. Is more preferable.
  • the total content of the polymer (A) and the polymer (B) in the binder composition can be appropriately adjusted according to the specifications and the like, and is not particularly limited.
  • the total content of the polymer (A) and the polymer (B) in the binder composition is preferably 1.0% by mass or more, more preferably 5.0% by mass or more, and 10%. It is more preferably 0.0% by mass or more. This is because, in the case of producing the slurry described later, the content of the binder can be sufficiently maintained without removing the components such as the aqueous medium.
  • the total content of the polymer (A) and the polymer (B) in the binder composition is preferably 70% by mass or less, more preferably 50% by mass or less. This is to prevent the viscosity of the binder composition from becoming too high.
  • the separator slurry for a non-aqueous secondary battery according to the present embodiment includes the above-mentioned separator binder for a non-aqueous secondary battery, a filler, and an aqueous medium.
  • the separator binder for a non-aqueous secondary battery is as described above.
  • the separator slurry for a non-aqueous secondary battery may be used as a slurry.
  • the slurry according to the present embodiment may contain a component derived from the component used for producing the binder, or may contain a binder or the like other than the binder of the present invention.
  • the filler may be either an organic filler or an inorganic filler, and these may be used in combination.
  • the filler preferably contains an inorganic filler, and more preferably consists of an inorganic filler.
  • Inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, hydrotalcite, diatomaceous soil, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide. , Titanium oxide, alumina, mica, zeolite, glass and the like.
  • the inorganic filler may be particles made of one kind of material, or may contain particles made of two or more kinds of materials. Further, the inorganic filler may be prepared by mixing particles having different particle size distributions.
  • the filler preferably contains metal oxide particles, and more preferably contains alumina particles. This is because the alumina particles have an excellent affinity with the binder according to the present embodiment, have good dispersibility during kneading, and can obtain a slurry having a low viscosity and good coatability.
  • the average particle size of the particles constituting the filler is preferably 3 ⁇ m or less, and more preferably 1 ⁇ m or less.
  • the average particle size referred to here is a number average value of the primary particle size obtained by SEM (scanning electron microscope) observation. Specifically, 100 particles of the filler reflected in the SEM are randomly selected, the longest dimension of each particle is measured, and the average value of these measured dimensions is the average particle size of the filler.
  • the value of the mass ratio (binder content / filler content) between the binder content and the filler content in the slurry is preferably 1.0 / 99.0 or more, and 2.0 / 98. It is more preferably 0 or more, and further preferably 4.0 / 96.0 or more. This is to improve the peel strength of the coating layer made from the slurry to the substrate and to sufficiently fix the filler particles to the coating layer. It is also for improving the heat resistance of the coating layer.
  • the value of the mass ratio of the content of the binder to the content of the filler in the slurry is preferably 15.0 / 85.0 or less, more preferably 10.0 / 90.0 or less, and 7. It is more preferably 0 / 93.0 or less. This is to obtain a battery having good load characteristics by sufficiently maintaining the air permeability and the permeability of ions in the separator described later.
  • a mixed solvent of water and an organic solvent having a boiling point at atmospheric pressure of 50 to 150 ° C. and compatible with water may be used.
  • the organic solvent are the same as those of the compound exemplified in the section of the binder composition.
  • the content of the organic solvent with respect to 100 parts by mass of water is not particularly limited, but is preferably 100 parts by mass or less, and is preferably 20 parts by mass or less. Is more preferable.
  • the content of the aqueous medium in the slurry can be appropriately adjusted according to the specifications and the like, and is not limited.
  • the content of the aqueous medium in the slurry is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less. This is because when the slurry is applied to the substrate, a coating layer having a sufficient thickness can be formed with a smaller amount of slurry.
  • the content of the aqueous medium in the slurry is preferably 20% by mass or more, more preferably 30% by mass or more, and further preferably 40% by mass or more. This is to keep the viscosity of the slurry within a range suitable for coating.
  • Manufacturing method of separator slurry for non-aqueous secondary batteries for example, a first method in which a polymer (A) and a polymer (B) are mixed in an aqueous medium to prepare a binder composition, and then a filler is mixed and dispersed; a filler and a weight are used. A second method in which the coalescence (A) is mixed in an aqueous medium, the filler is dispersed, and then the polymer (B) is added; the filler and the polymer (B) are mixed in the aqueous medium, and the filler is dispersed.
  • the second method is preferable in order to improve the peel strength of the coating layer described later.
  • the first method of preparing the binder composition in advance may be preferable in order to reduce the production cost of the slurry and the management cost of the material.
  • the separator for a non-aqueous secondary battery according to the present embodiment includes a base material which is a porous film and a coating layer formed on the surface of the base material.
  • the coating layer according to the present embodiment may be formed on either of the surfaces of the base material facing the positive electrode and the surface facing the negative electrode, or may be formed on both surfaces.
  • the separator for a non-aqueous secondary battery may include, for example, an adhesive layer, a protective layer, and the like.
  • the separator for a non-aqueous secondary battery according to the present embodiment may be referred to as a separator.
  • the material of the base material examples include thermoplastic resins such as polyolefin, papermaking such as biscorayon and natural cellulose, mixed papermaking obtained by papermaking fibers such as cellulose and polyester, electrolytic paper, kraft paper, and Manila paper. , Manila hemp sheet, glass fiber, porous polyester, aramid fiber, polybutylene terephthalate non-woven fabric, para-aramid, vinylidene fluoride, tetrafluoroethylene, copolymer of vinylidene fluoride and propylene hexafluoride, fluororubber, etc.
  • examples thereof include a non-woven fabric such as a fluororesin or a porous film.
  • the material of the base material is preferably polyolefin.
  • the polyolefin include homopolymers or copolymers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Of these, a copolymer mainly composed of ethylene or a homopolymer of ethylene is preferable, and a homopolymer of ethylene, that is, polyethylene is more preferable.
  • the thickness of the base material is preferably 5 to 50 ⁇ m, more preferably 5 to 30 ⁇ m.
  • a commercially available porous film may be used as the base material.
  • the coating layer contains the above-mentioned separator binder for a non-aqueous secondary battery and the above-mentioned filler.
  • the thickness of the coating layer is not particularly limited, but is preferably 10 ⁇ m or less. This is to improve the load characteristics of the non-aqueous electrolyte secondary battery provided with the separator.
  • the method for producing the separator for a non-aqueous secondary battery is not particularly limited, and examples thereof include a method in which the slurry according to the present embodiment is applied to the surface of the base material and the applied slurry is dried. Before applying the slurry to the surface of the base material, the base material may be subjected to surface treatment such as corona treatment in advance.
  • Examples of the method of applying the slurry to the surface of the base material include industrially usual methods such as application with a doctor blade.
  • the thickness of the coating layer can be controlled by adjusting the coating amount of the slurry, the concentration of the solid content in the slurry, and the like.
  • drying the slurry applied to the base material By drying the slurry applied to the base material, volatile components are removed from the slurry and a coating layer is formed.
  • the drying include a method using a heating device such as a drying furnace, a method using a depressurizing device, a method of performing both heating and depressurization, and the like.
  • Conditions such as heating, depressurization, and drying time can be appropriately selected according to the material and form of the base material, the type of solvent contained in the volatile matter, etc.
  • the drying temperature is equal to or lower than the melting point or glass transition point of the base material. It is preferable to set it in the range of.
  • the drying temperature of the slurry is preferably 100 ° C. or lower, more preferably 80 ° C.
  • the temperature is preferably 50 ° C. or higher. Further, it is preferable to set the depressurization condition to such an extent that bubbles and the like are not generated in the coating layer while considering productivity.
  • the drying conditions are preferably 55 to 65 ° C. for 2 to 10 minutes, and 60 ° C. for 5 minutes. It is more preferable to do so. This is to prevent the pores in the porous film from being crushed due to softening or melting of the thermoplastic resin contained in the porous film. It was
  • Non-water-based secondary battery has a configuration in which a positive electrode, a negative electrode, an electrolytic solution, and a separator are housed in an exterior body.
  • the separator is arranged between the positive electrode and the negative electrode. It is preferable that the positive electrode active material layer of the positive electrode and the negative electrode active material layer of the negative electrode are arranged so as to face each other with the separator interposed therebetween.
  • the separator has the above-mentioned configuration.
  • the non-aqueous secondary battery is a lithium ion secondary battery
  • the non-aqueous secondary battery is not limited to this, and for example, a potassium ion secondary battery, a sodium ion secondary battery, etc. But it may be.
  • Electrodes positive electrode and negative electrode
  • the electrode includes a current collector and an electrode active material layer formed on the current collector.
  • a metal foil is used as the current collector, and in the case of a lithium ion secondary battery, an aluminum foil is preferably used as the positive electrode and a copper foil is preferably used as the negative electrode.
  • Examples of the shape of the current collector include a foil, a flat plate, a mesh, a net, a lath, a punching shape, an embossed shape, or a combination thereof (for example, a mesh flat plate). ..
  • the surface of the current collector may have irregularities formed by etching.
  • the electrode active material layer has a structure in which the electrode active material is fixed to the current collector via the electrode binder. Further, the electrode active material layer may contain an additive such as a conductive auxiliary agent.
  • the electrode active material can store and release ions that become charge carriers (lithium ions in the case of a lithium ion secondary battery), and the positive electrode active material uses a material that is electrochemically more precious than the negative electrode active material. ..
  • a lithium composite oxide containing nickel such as a Ni—Co—Mn-based lithium composite oxide, a Ni—Mn—Al based lithium composite oxide, and a Ni—Co—Al based lithium composite oxide.
  • these substances may be used alone or in combination of two or more.
  • the negative electrode active material examples include silicon, silicon oxide (SiO 2 and the like), carbonaceous substances, metal composite oxides and the like, and preferably carbonaceous materials such as amorphous carbon, artificial graphite and natural graphite;
  • a x M. y O z In the formula, A is Li, M is at least one selected from Co, Ni, Al, Sn and Mn, O is an oxygen atom, and x, y and z are 1.10 ⁇ x ⁇ 0, respectively. .05, 4.00 ⁇ y ⁇ 0.85, 5.00 ⁇ z ⁇ 1.5), and other metal oxides and the like.
  • the negative electrode active material may be composed of one kind of substance or may be composed of two or more kinds of substances.
  • the binder according to this embodiment may be used, or other resin or the like may be used.
  • the material used as the electrode binder is an acrylic obtained by copolymerizing a monomer containing (meth) acrylic acid ester and (meth) acrylic acid in addition to the polymer (A) and the polymer (B) described in the present embodiment. Examples thereof include, but are not limited to, a system copolymer, a copolymer of (meth) acrylate and N-vinylacetamide, styrene-butadiene rubber, and polyvinylidene fluoride. Further, the electrode binder may contain a plurality of types of materials.
  • carbon black examples include furnace black, acetylene black, denka black (registered trademark) (manufactured by Denka Co., Ltd.), and Ketjen black (registered trademark) (manufactured by Ketjen Black International Co., Ltd.).
  • Examples of the carbon fiber include carbon nanotubes and carbon nanofibers, and examples of the carbon nanotube include VGCF (registered trademark, manufactured by Showa Denko Co., Ltd.), which is a vapor phase carbon fiber.
  • Electrolyte examples of the electrolytic solution include a solution in which an electrolyte is dissolved in an organic solvent and an ionic liquid, and a solution is preferable.
  • an alkali metal salt can be used and can be appropriately selected depending on the type of the electrode active material and the like.
  • the electrolyte include LiClO 4 , LiBF 6 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiB 10 Cl 10 , LiAlCl 4 , LiCl, LiBr, LiB (C2H 5 ). 4 , CF 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3 , LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ) 2 N, lithium aliphatic carboxylate and the like can be mentioned. Further, other alkali metal salts can also be used as the electrolyte.
  • the organic solvent that dissolves the electrolyte is not particularly limited, and is, for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), and fluoroethylene carbonate.
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • MEC methyl ethyl carbonate
  • DMC dimethyl carbonate
  • fluoroethylene carbonate examples thereof include carbonic acid ester compounds such as (FEC) and vinylene carbonate (VC), nitrile compounds such as acetonitrile, and carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate and propyl propionate.
  • FEC propylene carbonate
  • MEC methyl ethyl carbonate
  • DMC dimethyl carbonate
  • fluoroethylene carbonate
  • the exterior body for example, a laminated material of an aluminum foil and a resin film can be appropriately used, but the exterior body is not limited to this.
  • the shape of the battery may be any shape such as a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.
  • any one of “polymer (A-1) to polymer (A-6)” may be referred to as “polymer (A)".
  • polymer (CA-1), polymer (CA-2), or polymer (CA-3) (described later) may be referred to as “polymer (CA)”.
  • Step 1 In the synthesis of each polymer, ion-exchanged water was poured into a reaction vessel equipped with a stirrer, a thermometer and a condenser in the amount shown in the column of step 1 in Table 1, and the temperature was 80 ° C. while stirring in a nitrogen atmosphere. The temperature was raised to.
  • Step 2 When the temperature reached 80 ° C., an initiator aqueous solution prepared by dissolving 0.50 g of ammonium persulfate in 6.6 g of ion-exchanged water was added in a batch. Simultaneously with the addition of the initiator aqueous solution, in the synthesis of each polymer, 50% by mass acrylamide aqueous solution, 2-hydroxyethyl acrylate, and ion-exchanged water were started to be dropped in the amounts shown in the column of step 2 in Table 1, and then dropped. Went for 30 minutes. Then, the reaction was carried out at 80 ° C. for 2 hours. The amount of Am alone in Table 1 is the mass (g) of acrylamide contained in the aqueous acrylamide solution used.
  • Step 3 Then, in the synthesis of each polymer, ion-exchanged water was added in the amount shown in the column of step 3 in Table 1.
  • the non-volatile content, viscosity, pH, and weight average molecular weight of the polymer were measured by the methods described below, and the measurement results are shown in Table 1.
  • aqueous solution of the polymer (A) and the aqueous solution of the polymer (CA) were measured by a Brookfield viscometer (manufactured by Toki Sangyo Co., Ltd.) at a liquid temperature of 23 ° C. and a rotation speed of 10 rpm. 3, No. 4 and No. Viscosity was measured using any of the rotors of 5. The rotor is selected according to the viscosity of each aqueous solution.
  • GPC device GPC-101 (manufactured by Showa Denko KK) Solvent: 0.1M NaNO 3 aqueous solution
  • Sample column Shodex Volume Ohpak SB-806 HQ (8.0 mm ID x 300 mm) x 2 Reference column: Shodex Colon Ohpak SB-800 RL (8.0 mm ID x 300 mm) x 2
  • Column temperature 40 ° C
  • Pump DU-H2000 (manufactured by Shimadzu Corporation) Pressure: 1.3MPa Flow rate: 1 ml / min
  • Molecular weight standard Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (Showa Denko KK) Made))
  • Table 1 shows the copolymerization ratio of the produced polymer, that is, the mass ratio of the structural unit derived from acrylamide and the structural unit derived from 2-hydroxyethyl acrylate in the polymer.
  • the copolymerization ratio shown here is the mass ratio of acrylamide and 2-hydroxyethyl acrylate used in step 2.
  • the saponification degree of the polymers (B-1) to (B-4) was measured by the measuring method of JIS K6726 (1994) Section 3.5 (the simple method is not used).
  • the degree of polymerization of the polymers (B-1) to (B-4) was measured by the measuring method of JIS K6726 (1994) Section 3.7.
  • the non-volatile content (mass%) and viscosity (mPa ⁇ s) of the prepared aqueous solution were measured by the same method as that of the aqueous solution of the polymer (A), and the measurement results are shown in Table 2.
  • Example 1 the components used in each Example / Comparative Example and their amounts are as shown in Tables 3 to 5.
  • Example 1 a 14.5% by mass aqueous solution of the polymer (A-2) was added in an amount of 65.5 g (9.5 g of the polymer (A-2) and 56.0 g of water).
  • the amount of alumina added is as shown in Tables 3 to 5. For example, in Example 1, 190 g of alumina was added.
  • the amount of ion-exchanged water added is combined with the water contained in the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA) for Examples 1 to 8 and 14 to 21 and Comparative Examples 1 to 4. It was adjusted to 100 g. For example, in Example 1, 44.0 g of ion-exchanged water was added. Further, in Examples 10 to 12, 23 to 25 and Comparative Example 5, the amount of ion-exchanged water added was 233 g including the water contained in the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA). Adjusted to be.
  • the types of the aqueous solution of the polymer (B) used in each Example / Comparative Example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (B) added is the polymer (B).
  • the amount of the above was adjusted to be the amount shown in Tables 3 to 5.
  • Example 1 5.0 g (0.50 g of polymer (B-1), 4.5 g of water) of a 10.0 mass% aqueous solution of the polymer (B-1) was added.
  • the amount of ion-exchanged water added in this step was adjusted to 100 g together with the water contained in the aqueous solution of the polymer (B). For example, in Example 1, 95.5 g of ion-exchanged water was added.
  • preparation method I The slurry preparation method described above is referred to as preparation method I in Tables 3 to 5.
  • the types of the aqueous solution of the polymer (A) used in each example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (A) added is the amount of the polymer (A).
  • the amount was adjusted to be as shown in Tables 3 to 5.
  • 55.2 g (8.0 g of the polymer (A-2) and 47.2 g of water) of a 14.5% by mass aqueous solution of the polymer (A-2) was added.
  • the amount of alumina added was 190 g in Example 9 and 323 g in Example 13.
  • the types of the aqueous solution of the polymer (B) used in each example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (B) added is the amount of the polymer (B).
  • the amount was adjusted to be as shown in Tables 3 to 5.
  • a 10.0 mass% aqueous solution of the polymer (B-1) was added in an amount of 20.0 g (2.0 g of the polymer (B-1) and 18.0 g of water).
  • Example 9 The amount of ion-exchanged water added was 34.8 g in Example 9 and 170.9 g in Example 13.
  • preparation method II The slurry preparation method described above is referred to as preparation method II in Tables 3 to 5.
  • Comparative Example 7 A slurry was prepared in the same manner as in Comparative Example 6 except that the same amount of a 14.5% by mass aqueous solution of the polymer (CA-1) was used.
  • Comparative Example 10 A slurry was prepared in the same manner as in Comparative Example 9 except that the same amount of a 10.0% by mass aqueous solution of the polymer (B-4) was used instead of the 10.0% by mass aqueous solution of the polymer (B-3). ..
  • Comparative Example 11 In Comparative Example 11, the slurry was not prepared, and the evaluation was performed using only the separator described later.
  • Comparative Example 11 the slurry was not applied to the separator, and only the heat shrinkage described later was evaluated.
  • peeling strength of coating layer The peel strength of the coating layer with respect to the substrate was measured as follows. A separator having coating layers on both sides produced by the above step was cut into a size of 15 mm ⁇ 100 mm to obtain a test piece.
  • the pasting was performed by reciprocating a 2 kg roller once in an atmosphere of 23 ° C. After leaving the cellophane tape attached to the coating layer for 20 minutes, one end of the cellophane tape is folded back 180 ° and pulled toward the other end facing the other end at a speed of 100 mm / min to peel it off, and the peeling length (mm). ) -A graph of peeling force (mN) was obtained.
  • a testing machine Teensilon RTG-1210 (manufactured by A & D Co., Ltd.) was used.
  • the average value (mN) of the peeling force at the peeling length of 10 to 45 mm was calculated, and the value obtained by dividing the average value of the peeling force by the width of the test piece of 15 mm was the peeling strength (mN / mm) of the coating layer. And said.
  • the peeling strength (mN / mm) of the coating layer was the peeling strength (mN / mm) of the coating layer.
  • the separator was placed on a stainless steel plate having a thickness of 0.8 mm, a length of 150 mm, a width of 70 mm, and a mass of 65 g, and a stainless steel plate of the same size and mass was placed on the separator. That is, the separator is sandwiched between two stainless steel plates, and the separator is fixed by the weight of the upper stainless steel plate.
  • the separator sandwiched between the stainless steel plates was allowed to stand in a constant temperature bath at 150 ° C. for 60 minutes. After taking out the separator, the length in the MD direction was read with a caliper, and the heat shrinkage rate was calculated according to the following equation.
  • Heat shrinkage rate (%) [ ⁇ (100 (mm) -length after heating (mm)) / 100 (mm) ⁇ x 100]
  • Comparative Example 1 a slurry was prepared using a polymer (CA-1) containing a large amount of structural units (first structural unit (a1)) derived from acrylamide instead of the polymer (A). However, the produced slurry could not be applied to the base material, and a coating layer was not formed.
  • Comparative Example 6 a binder containing no polymer (B) was used, but the peel strength of the formed coating layer was not sufficient.
  • Comparative Example 7 a polymer (CA-1) containing a large amount of structural units derived from acrylamide (first structural unit (a1)) is used instead of the polymer (A), and the polymer (B) is not contained.
  • a slurry was prepared. However, the produced slurry had insufficient wettability to the base material, the slurry could not be applied to the base material, and the coating layer could not be formed.
  • Comparative Example 9 and Comparative Example 10 a binder containing no polymer (A) was used, but the formed coating layer could not sufficiently suppress the thermal shrinkage of the separator.
  • Comparative Example 11 the evaluation was performed using a separator containing only the base material without forming the coating layer, but the heat shrinkage of the separator was large.
  • the present invention it is possible to produce a slurry having good wettability to a substrate and good coatability, a coating layer having high peel strength can be formed on the separator, and the heat of the separator can be formed. It can be said that it is possible to provide a separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery capable of suppressing shrinkage. Further, according to the present invention, it can be said that it is possible to provide a separator for a non-aqueous secondary battery which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.

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Abstract

Provided are a separator binder for a nonaqueous secondary battery and a separator binder composition for a nonaqueous secondary battery that make it possible to produce a slurry having good wettability and coatability on a substrate, that make it possible to form a coating layer having high peel strength on a separator, and that can suppress heat shrinkage of the separator. The separator binder for a nonaqueous secondary battery of the present invention comprises a polymer (A) and a polymer (B). In the polymer (A), the main chain is a polyolefin structure and has a first structural unit (a1) derived from a (meth)acrylamide and a second structural unit (a2) derived from a compound having a hydroxyl group and an ethylenic unsaturated bond. The polymer (B) is a polyvinyl alcohol having a degree of saponification of 55 mol% or more. In the polymer (A), the value of the mass ratio of (a1) and (a2) is from 55.0/45.0 to 95.0/5.0, and the value of the mass ratio of (A) and (B) is from 55.0/45.0 to 97.0/3.0.

Description

非水系二次電池用セパレータバインダー、非水系二次電池用セパレータ、非水系二次電池用セパレータスラリーの製造方法、及び非水系二次電池Separator binder for non-aqueous secondary batteries, separator for non-aqueous secondary batteries, method for manufacturing separator slurry for non-aqueous secondary batteries, and non-aqueous secondary batteries
　本発明は、非水系二次電池用セパレータバインダー、非水系二次電池用セパレータ、非水系二次電池用セパレータスラリーの製造方法、及び非水系二次電池に関する。
　本願は、２０２０年１２月２４日に、日本に出願された特願２０２０－２１４８７９号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a separator binder for a non-aqueous secondary battery, a separator for a non-aqueous secondary battery, a method for producing a separator slurry for a non-aqueous secondary battery, and a non-aqueous secondary battery.
This application claims priority based on Japanese Patent Application No. 2020-214879 filed in Japan on December 24, 2020, the contents of which are incorporated herein by reference.
　代表的な非水系二次電池として、例えばリチウムイオン二次電池は、リチウムイオンが正極と負極との間を移動することにより電池の充放電が行われる二次電池である。リチウムイオン二次電池は主要な構成として、アルミニウム等の集電体表面にコバルト酸リチウム等の金属酸化物を含む正極活物質層が形成された正極と、銅等の集電体表面に黒鉛等の材料を含む負極活物質層が形成された負極と、正極及び負極の間に設けられるセパレータと、リチウム塩等の電解質をカーボネート等の溶媒に溶解させた電解液と、を含む。 As a typical non-aqueous secondary battery, for example, a lithium ion secondary battery is a secondary battery in which lithium ions move between a positive electrode and a negative electrode to charge and discharge the battery. The main components of the lithium ion secondary battery are a positive electrode in which a positive electrode active material layer containing a metal oxide such as lithium cobaltate is formed on the surface of a current collector such as aluminum, and graphite or the like on the surface of the current collector such as copper. It contains a negative electrode on which a negative electrode active material layer containing the above-mentioned material is formed, a separator provided between the positive electrode and the negative electrode, and an electrolytic solution in which an electrolyte such as a lithium salt is dissolved in a solvent such as carbonate.
　セパレータは正極と負極との間を隔離するために設けられる部材で、非水系二次電池ではセパレータとして樹脂多孔質膜などの基材が広く使用されている。電池の発熱量が多くなると、セパレータの孔が塞がり、キャリアイオンの移動を防ぎ電池がシャットダウンする。しかし、近年、二次電池の高エネルギー密度化が進んでおり、使用時の電池の発熱量が多くなる傾向にある。そこでセパレータの耐熱性の付与のため、基材の少なくとも一方の面にバインダーと非導電性粒子とを含むコーティング層を形成させることが提案されている。コーティング層には、一般的に有機物または無機物の粒子（フィラー）と、粒子を基材表面上に固定するためのバインダーが含まれている。 The separator is a member provided to isolate between the positive electrode and the negative electrode, and a base material such as a resin porous membrane is widely used as a separator in non-aqueous secondary batteries. When the amount of heat generated by the battery increases, the holes in the separator are closed, preventing the movement of carrier ions and shutting down the battery. However, in recent years, the energy density of secondary batteries has been increasing, and the amount of heat generated by the batteries during use tends to increase. Therefore, in order to impart heat resistance to the separator, it has been proposed to form a coating layer containing a binder and non-conductive particles on at least one surface of the base material. The coating layer generally contains organic or inorganic particles (fillers) and a binder for fixing the particles on the surface of the substrate.
　このような提案として、例えば、特許文献１においては、アルミナ短繊維、ポリフッ化ビニリデン、及びＮ－メチルピロリドンを含む混合物を多孔性のポリプロピレンシートに塗布することが記載されている。 As such a proposal, for example, Patent Document 1 describes applying a mixture containing alumina staple fibers, polyvinylidene fluoride, and N-methylpyrrolidone to a porous polypropylene sheet.
　特許文献２では、水溶性ポリマーの多孔膜とポリオレフィンの多孔膜とが積層された非水電解液二次電池用セパレータが記載されており、水溶性ポリマーとして、ポリビニルアルコール、カルボキシメチルセルロース（ＣＭＣ）等が記載されている。実施例においては、ＣＭＣ及びアルミナ微細粒子を含むスラリーを多孔質フィルム上に塗布してセパレータを作製することが記載されている。 Patent Document 2 describes a separator for a non-aqueous electrolytic solution secondary battery in which a porous membrane of a water-soluble polymer and a porous membrane of a polyolefin are laminated, and examples of the water-soluble polymer include polyvinyl alcohol and carboxymethyl cellulose (CMC). Is described. In the examples, it is described that a slurry containing CMC and alumina fine particles is applied onto a porous film to prepare a separator.
　特許文献３には、ポリオレフィン樹脂多孔膜の少なくとも片面に、無機フィラーとけん化度８５％以上のポリビニルアルコールからなる多孔層を備えた多層多孔膜が記載されている。 Patent Document 3 describes a multilayer porous membrane provided with a porous layer composed of an inorganic filler and polyvinyl alcohol having a saponification degree of 85% or more on at least one surface of the polyolefin resin porous membrane.
　特許文献４には、金属カルボキシラート基を有する水溶性高分子と、水酸基、カルボキシ基又はスルホ基を有する水溶性高分子とを含むバインダー用樹脂組成物を、非水電解液二次電池用セパレーター基材表面にフィラー粒子を結着させるために使用することが記載されている。実施例には、バインダーとしてカルボキシメチルセルロースとポリビニルアルコールとを併用し、溶媒として水を用いた例が記載されている。 Patent Document 4 describes a resin composition for a binder containing a water-soluble polymer having a metal carboxylate group and a water-soluble polymer having a hydroxyl group, a carboxy group or a sulfo group, as a separator for a non-aqueous electrolyte secondary battery. It is described that it is used to bind filler particles to the surface of a substrate. Examples describe an example in which carboxymethyl cellulose and polyvinyl alcohol are used in combination as a binder and water is used as a solvent.
特許第３７５６８１５号公報Japanese Patent No. 3756815 特開２００４－２２７９７２号公報Japanese Unexamined Patent Publication No. 2004-227972 特開２００８－１８６７２１号公報Japanese Unexamined Patent Publication No. 2008-186721 国際公開第２０１３／１５４１９７号International Publication No. 2013/154197
　しかしながら、特許文献１に記載の構成では、溶媒にＮ－メチルピロリドンを用いた場合、乾燥温度を高くする必要があり多孔質有機フィルムへの負荷が大きい。また、ポリフッ化ビニリデンは、親水性に乏しく、溶媒として水を用いる近年のニーズに応えることが困難である。 However, in the configuration described in Patent Document 1, when N-methylpyrrolidone is used as the solvent, it is necessary to raise the drying temperature and the load on the porous organic film is large. In addition, polyvinylidene fluoride has poor hydrophilicity, and it is difficult to meet the recent needs for using water as a solvent.
　特許文献２においては、ＣＭＣ樹脂は無機フィラーの分散性が劣り、高粘度のスラリーとなりやすく、塗工性が低下しやすい。また、それらを用いたスラリーはポリオレフィン多孔質フィルムへの濡れ性に劣る。得られるセパレータの耐熱性も不十分である。また、スラリーを乾燥して得られた層は、ポリオレフィン多孔質フィルムへの密着性に劣ることから、作製した積層多孔質セパレータは粉落ちが発生しやすい。 In Patent Document 2, the CMC resin is inferior in dispersibility of the inorganic filler, tends to be a highly viscous slurry, and tends to deteriorate in coatability. Further, the slurry using them is inferior in wettability to the polyolefin porous film. The heat resistance of the obtained separator is also insufficient. Further, since the layer obtained by drying the slurry is inferior in adhesion to the polyolefin porous film, the produced laminated porous separator is liable to cause powder falling off.
　特許文献３においては、多孔質層の高温での寸法安定性が不十分である。 In Patent Document 3, the dimensional stability of the porous layer at high temperature is insufficient.
　特許文献４においては、ＣＭＣ樹脂を配合したスラリーは粘度が高く、塗工性が劣る。 In Patent Document 4, the slurry containing the CMC resin has a high viscosity and is inferior in coatability.
　そこで、本発明は、基材への濡れ性及び塗工性が良好なスラリーの作製が可能で、剥離強度の高いコーティング層をセパレータに形成させることが可能で、かつセパレータの熱収縮を抑制できる非水系二次電池用セパレータバインダー及び非水系二次電池用セパレータバインダー組成物を提供することを目的とする。また、本発明は、基材に対する剥離強度が高いコーティング層を備え、熱収縮の小さい非水系二次電池用セパレータを提供することを目的とする。 Therefore, according to the present invention, it is possible to produce a slurry having good wettability to a substrate and good coatability, it is possible to form a coating layer having high peel strength on a separator, and it is possible to suppress thermal shrinkage of the separator. It is an object of the present invention to provide a separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery. Another object of the present invention is to provide a separator for a non-aqueous secondary battery, which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.
　上記課題を解決するため、本発明は以下の［１］～［１７］の通りである。
［１］　重合体（Ａ）及び重合体（Ｂ）を含む非水系二次電池用セパレータバインダーであって、　前記重合体（Ａ）は、エチレン性不飽和結合を有する化合物の重合体であり、（メタ）アクリルアミドに由来する第１構造単位（ａ１）と、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）と有し、
　前記重合体（Ｂ）は、けん化度５５ｍｏｌ％以上のポリビニルアルコールであり、
　前記重合体（Ａ）における、前記第１構造単位（ａ１）の含有量と前記第２構造単位（ａ２）の含有量との質量比の値は、５５．０／４５．０以上９５．０／５．０以下であり、　前記重合体（Ａ）の含有量と前記重合体（Ｂ）の含有量との質量比の値は、５５．０／４５．０以上９７．０／３．０以下である非水系二次電池用セパレータバインダー。
［２］　前記重合体（Ａ）及び前記重合体（Ｂ）のみからなる、［１］に記載の非水系二次電池用セパレータバインダー。
［３］　前記重合体（Ａ）は、アニオン性官能基を有さない［１］または［２］に記載の非水系二次電池用セパレータバインダー。
［４］　前記重合体（Ｂ）は、けん化度６５ｍｏｌ％以上である［１］～［３］のいずれかに記載の非水系二次電池用セパレータバインダー。
［５］　前記重合体（Ｂ）は、重合度１００以上５０００以下である［１］～［４］のいずれかに記載の非水系二次電池用セパレータバインダー。
［６］　前記重合体（Ａ）における、前記第１構造単位（ａ１）及び前記第２構造単位（ａ２）の合計含有率は８０質量％以上である［１］～［５］のいずれかに記載の非水系二次電池用セパレータバインダー。
［７］　前記重合体（Ａ）は、前記第１構造単位（ａ１）及び前記第２構造単位（ａ２）のみからなる、［１］～［６］のいずれかに記載の非水系二次電池用セパレータバインダー。
［８］　前記第２構造単位（ａ２）は、水酸基を有する（メタ）アクリレートに由来する構造単位である［１］～［７］のいずれかに記載の非水系二次電池用セパレータバインダー。
［９］　前記第２構造単位（ａ２）は、２－ヒドロキシエチル（メタ）アクリレートである、［１］～［７］のいずれかに記載の非水系二次電池用セパレータバインダー。
［１０］　前記第２構造単位（ａ２）は、２－ヒドロキシエチルメタクリレートである、［１］～［７］のいずれかに記載の非水系二次電池用セパレータバインダー。
［１１］　前記重合体（Ａ）の水１００ｇへの溶解度は、２．０ｇ／１００ｇ以上である［１］～［１０］のいずれかに記載の非水系二次電池用セパレータバインダー。
［１２］　［１］～［１１］のいずれかに記載の非水系二次電池用セパレータバインダーと、水性媒体とを含む非水系二次電池用セパレータバインダー組成物。
［１３］　［１］～［１１］のいずれかに記載の非水系二次電池用セパレータバインダーと、フィラーと、水性媒体とを含む、非水系二次電池用セパレータスラリー。
［１４］　多孔質フィルムである基材と、該基材の表面に形成されたコーティング層とを備えた非水系二次電池用セパレータであって、
　前記コーティング層は、［１］～［１１］のいずれかに記載の非水系二次電池用セパレータバインダーと、フィラーとを含む非水系二次電池用セパレータ。
［１５］　前記コーティング層における、前記非水系二次電池用セパレータバインダーの含有量と前記フィラーの含有量との質量比の値は、１．０／９９．０以上１５．０／８５．０以下である［１４］に記載の非水系二次電池用セパレータ。
［１６］　非水系二次電池用セパレータスラリーの製造方法であって、
　重合体（Ａ）、及びフィラーを水性媒体中で混合する第１工程と、
　重合体（Ｂ）を、前記第１工程で得られた混合物に加えて混合する第２工程と、を含み、
　前記重合体（Ａ）は、エチレン性不飽和結合を有する化合物の重合体であり、（メタ）アクリルアミドに由来する第１構造単位（ａ１）と、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）と有し、
　前記重合体（Ｂ）は、けん化度５５ｍｏｌ％以上のポリビニルアルコールであり、
　前記重合体（Ａ）における、前記第１構造単位（ａ１）の含有量と前記第２構造単位（ａ２）の含有量との質量比の値は、５５．０／４５．０以上９５．０／５．０以下であり、
　前記重合体（Ａ）の使用量と前記重合体（Ｂ）の使用量との質量比の値は、５５．０／４５．０以上９７．０／３．０以下である非水系二次電池用セパレータスラリーの製造方法。
［１７］　［１４］又は［１５］に記載の非水系二次電池用セパレータを含む、非水系二次電池。 In order to solve the above problems, the present invention is as follows [1] to [17].
[1] A separator binder for a non-aqueous secondary battery containing the polymer (A) and the polymer (B), wherein the polymer (A) is a polymer of a compound having an ethylenically unsaturated bond. It has a first structural unit (a1) derived from (meth) acrylamide and a second structural unit (a2) derived from a compound having a hydroxyl group and an ethylenically unsaturated bond.
The polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. It is /5.0 or less, and the value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) is 55.0 / 45.0 or more and 97.0 / 3.0. The following separator binder for non-aqueous secondary batteries.
[2] The separator binder for a non-aqueous secondary battery according to [1], which comprises only the polymer (A) and the polymer (B).
[3] The separator binder for a non-aqueous secondary battery according to [1] or [2], wherein the polymer (A) does not have an anionic functional group.
[4] The separator binder for a non-aqueous secondary battery according to any one of [1] to [3], wherein the polymer (B) has a saponification degree of 65 mol% or more.
[5] The separator binder for a non-aqueous secondary battery according to any one of [1] to [4], wherein the polymer (B) has a degree of polymerization of 100 or more and 5000 or less.
[6] The total content of the first structural unit (a1) and the second structural unit (a2) in the polymer (A) is 80% by mass or more, any of [1] to [5]. The above-mentioned separator binder for non-aqueous secondary batteries.
[7] The non-aqueous secondary battery according to any one of [1] to [6], wherein the polymer (A) comprises only the first structural unit (a1) and the second structural unit (a2). For separator binder.
[8] The separator binder for a non-aqueous secondary battery according to any one of [1] to [7], wherein the second structural unit (a2) is a structural unit derived from a (meth) acrylate having a hydroxyl group.
[9] The separator binder for a non-aqueous secondary battery according to any one of [1] to [7], wherein the second structural unit (a2) is 2-hydroxyethyl (meth) acrylate.
[10] The separator binder for a non-aqueous secondary battery according to any one of [1] to [7], wherein the second structural unit (a2) is 2-hydroxyethyl methacrylate.
[11] The separator binder for a non-aqueous secondary battery according to any one of [1] to [10], wherein the polymer (A) has a solubility in 100 g of water of 2.0 g / 100 g or more.
[12] A separator binder composition for a non-aqueous secondary battery, which comprises the separator binder for a non-aqueous secondary battery according to any one of [1] to [11] and an aqueous medium.
[13] A separator slurry for a non-aqueous secondary battery, which comprises the separator binder for a non-aqueous secondary battery according to any one of [1] to [11], a filler, and an aqueous medium.
[14] A separator for a non-aqueous secondary battery comprising a substrate which is a porous film and a coating layer formed on the surface of the substrate.
The coating layer is a separator for a non-aqueous secondary battery containing the separator binder for a non-aqueous secondary battery according to any one of [1] to [11] and a filler.
[15] The value of the mass ratio of the content of the separator binder for a non-aqueous secondary battery and the content of the filler in the coating layer is 1.0 / 99.0 or more and 15.0 / 85.0 or less. The separator for a non-aqueous secondary battery according to [14].
[16] A method for producing a separator slurry for a non-aqueous secondary battery.
The first step of mixing the polymer (A) and the filler in an aqueous medium, and
A second step of adding and mixing the polymer (B) to the mixture obtained in the first step is included.
The polymer (A) is a polymer of a compound having an ethylenically unsaturated bond, and is derived from a first structural unit (a1) derived from (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond. Has a second structural unit (a2) to be
The polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. /5.0 or less,
The value of the mass ratio of the amount of the polymer (A) used and the amount of the polymer (B) used is 55.0 / 45.0 or more and 97.0 / 3.0 or less, which is a non-aqueous secondary battery. Method for manufacturing separator slurry.
[17] A non-aqueous secondary battery comprising the separator for a non-aqueous secondary battery according to [14] or [15].
　本発明によれば、基材への濡れ性及び塗工性が良好なスラリーの作製が可能で、剥離強度の高いコーティング層をセパレータに形成させることが可能で、かつセパレータの熱収縮を抑制できる非水系二次電池用セパレータバインダー及び非水系二次電池用セパレータバインダー組成物を提供することができる。また、本発明によれば、基材に対する剥離強度が高いコーティング層を備え、熱収縮の小さい非水系二次電池用セパレータを提供することができる。 According to the present invention, it is possible to produce a slurry having good wettability to a substrate and good coatability, it is possible to form a coating layer having high peel strength on a separator, and it is possible to suppress thermal shrinkage of the separator. A separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery can be provided. Further, according to the present invention, it is possible to provide a separator for a non-aqueous secondary battery, which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.
　以下、本発明の実施形態として、非水系二次電池用セパレータバインダー（非水系二次電池セパレータ用バインダーともいう）、非水系二次電池用セパレータバインダー組成物（非水系二次電池セパレータ用バインダー組成物ともいう）、非水系二次電池用セパレータスラリー（非水系二次電池セパレータ用スラリーともいう）について説明する。 Hereinafter, as an embodiment of the present invention, a separator binder for a non-aqueous secondary battery (also referred to as a binder for a non-aqueous secondary battery separator) and a separator binder composition for a non-aqueous secondary battery (binder composition for a non-aqueous secondary battery separator) (Also referred to as a thing), a separator slurry for a non-aqueous secondary battery (also referred to as a slurry for a non-aqueous secondary battery separator) will be described.
　以下に述べる実施形態では、これらをコーティング層に適用した非水系二次電池用セパレータについても説明する。すなわち、以下に説明する実施形態においては、非水系二次電池用セパレータバインダーは非水系二次電池用セパレータに適用するためのバインダーであり、非水系二次電池用セパレータバインダー組成物は非水系二次電池用セパレータに適用するためのバインダー組成物であり、非水系二次電池用セパレータスラリーは非水系二次電池用セパレータに適用するためのセパレータスラリーである。 In the embodiment described below, a separator for a non-aqueous secondary battery to which these are applied to a coating layer will also be described. That is, in the embodiment described below, the separator binder for a non-aqueous secondary battery is a binder for applying to a separator for a non-aqueous secondary battery, and the separator binder composition for a non-aqueous secondary battery is a non-aqueous secondary battery. It is a binder composition for application to a separator for a secondary battery, and the separator slurry for a non-aqueous secondary battery is a separator slurry for application to a separator for a non-aqueous secondary battery.
　ただし、本実施形態の記載は本発明の範囲を限定しない。 However, the description of the present embodiment does not limit the scope of the present invention.
　「（メタ）アクリル」とは、アクリル及びメタクリルの総称であり、「（メタ）アクリレート」とは、アクリレート及びメタクリレートの総称である。 "(Meta) acrylic" is a general term for acrylic and methacrylic, and "(meth) acrylate" is a general term for acrylate and methacrylate.
　「不揮発分」は、直径５ｃｍのアルミ皿に組成物を１ｇ秤量し、１気圧（１０１３ｈＰａ）で、乾燥器内で空気を循環させながら１３０℃で１時間乾燥させ後に残った成分である。組成物の形態は、溶液、分散液、スラリーが挙げられるが、これらに限られない。「不揮発分濃度」とは、乾燥前の組成物の質量（１ｇ）に対する、上記条件下で乾燥後の不揮発分の質量割合（質量％）である。 The "nonvolatile component" is a component remaining after weighing 1 g of the composition in an aluminum dish having a diameter of 5 cm and drying at 130 ° C. for 1 hour while circulating air in a dryer at 1 atm (1013 hPa). The form of the composition includes, but is not limited to, a solution, a dispersion, and a slurry. The "nonvolatile content concentration" is the mass ratio (mass%) of the non-volatile content after drying under the above conditions with respect to the mass (1 g) of the composition before drying.
　「エチレン性不飽和結合」とは、特に断りがない限り、ラジカル重合性を有するエチレン性不飽和結合を指す。 "Ethylene unsaturated bond" refers to an ethylenically unsaturated bond having radical polymerization unless otherwise specified.
　「水酸基」は、炭素以外の原子に結合したＯＨ、カルボキシ基等のアニオン性官能基が有するＯＨ、及び芳香環を形成する炭素原子に結合したＯＨは含まない。 The "hydroxyl group" does not include OH bonded to an atom other than carbon, OH possessed by an anionic functional group such as a carboxy group, and OH bonded to a carbon atom forming an aromatic ring.
　エチレン性不飽和結合を有する化合物の重合体において、あるエチレン性不飽和結合を有する化合物に由来する構造単位は、その化合物のエチレン性不飽和結合以外の部分の化学構造と、重合体におけるその構造単位の主鎖を形成する部分以外の部分の化学構造とが同じであるとする。例えば、アクリルアミドに由来する構造単位は、重合体として主鎖以外の部分にＣＯＮＨ２の構造を有している。 In the polymer of a compound having an ethylenically unsaturated bond, the structural unit derived from the compound having a certain ethylenically unsaturated bond is the chemical structure of the portion other than the ethylenically unsaturated bond of the compound and its structure in the polymer. It is assumed that the chemical structure of the part other than the part forming the main chain of the unit is the same. For example, the structural unit derived from acrylamide has a structure of CONH 2 in a portion other than the main chain as a polymer.
　また、重合後に主鎖以外の部分を化学反応させる等、単量体の化学構造と重合体の化学構造とで対応しない場合は、重合後の化学構造を基準とする。例えば、酢酸ビニルを重合し、その後けん化した場合においては、重合体の化学構造を基準に考えて、けん化された構造単位は、ビニルアルコールに由来する構造単位とする。この定義に従うと、ポリ酢酸ビニルをけん化して得られるポリビニルアルコール（ＰＶＡ）は、けん化度が１００ｍｏｌ％でない場合、酢酸ビニルに由来する構造単位とビニルアルコールに由来する構造単位とを含む共重合体となる。このような共重合体において、例えば、ビニルアルコールに由来する構造単位を９０ｍｏｌ％、酢酸ビニルに由来する構造単位を１０ｍｏｌ％含む場合、便宜上、けん化度９０ｍｏｌ％のポリビニルアルコール（ＰＶＡ）と記載する。 If the chemical structure of the monomer does not correspond to the chemical structure of the polymer, such as the chemical reaction of parts other than the main chain after polymerization, the chemical structure after polymerization is used as the standard. For example, in the case where vinyl acetate is polymerized and then saponified, the saponified structural unit is a structural unit derived from vinyl alcohol in consideration of the chemical structure of the polymer. According to this definition, polyvinyl alcohol (PVA) obtained by saponifying polyvinyl acetate is a copolymer containing a structural unit derived from vinyl acetate and a structural unit derived from vinyl alcohol when the degree of saponification is not 100 mol%. Will be. In such a copolymer, for example, when the structural unit derived from vinyl alcohol is contained in 90 mol% and the structural unit derived from vinyl acetate is contained in 10 mol%, it is described as polyvinyl alcohol (PVA) having a saponification degree of 90 mol% for convenience.
　アニオン性官能基とは、ｐＨ７．０の水に溶解させた場合に、カチオン（水素イオン、金属イオン、アンモニウムイオン等）を放出する官能基である。アニオン性官能基としては、カルボキシ基、スルホ基、リン酸基、フェノール性水酸基等が挙げられる。 The anionic functional group is a functional group that releases cations (hydrogen ion, metal ion, ammonium ion, etc.) when dissolved in water having a pH of 7.0. Examples of the anionic functional group include a carboxy group, a sulfo group, a phosphoric acid group, a phenolic hydroxyl group and the like.
　以下の説明において、特に断りがなければ、表面は「ひょうめん」を意味する。 In the following explanation, unless otherwise specified, the surface means "hail noodles".
＜１．非水系二次電池用セパレータバインダー＞
　本発明の一実施形態にかかる非水系二次電池用セパレータバインダーは、重合体（Ａ）及び重合体（Ｂ）を含む。本発明の一実施形態にかかる非水系二次電池用セパレータバインダーは、前記重合体（Ａ）及び前記重合体（Ｂ）のみからなることが好ましい。重合体（Ａ）及び重合体（Ｂ）の各々について以下に説明する。 <1. Separator binder for non-aqueous secondary batteries ＞
The separator binder for a non-aqueous secondary battery according to an embodiment of the present invention includes a polymer (A) and a polymer (B). The separator binder for a non-aqueous secondary battery according to an embodiment of the present invention is preferably composed of only the polymer (A) and the polymer (B). Each of the polymer (A) and the polymer (B) will be described below.
［１－１．重合体（Ａ）］
　重合体（Ａ）は、エチレン性不飽和結合を有する化合物の重合体である。重合体（Ａ）は、（メタ）アクリルアミドに由来する第１構造単位（ａ１）と、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）とを含む共重合体である。重合体（Ａ）は、アニオン性官能基を有さないことが好ましい。重合体（Ａ）の水１００ｇへの溶解度は、２．０ｇ／１００ｇ以上であることが好ましく、５．０ｇ／１００ｇ以上であることがより好ましく、１０．０ｇ／１００ｇ以上であることがさらに好ましい。 [1-1. Polymer (A)]
The polymer (A) is a polymer of a compound having an ethylenically unsaturated bond. The polymer (A) is a copolymer containing a first structural unit (a1) derived from (meth) acrylamide and a second structural unit (a2) derived from a compound having a hydroxyl group and an ethylenically unsaturated bond. be. The polymer (A) preferably does not have an anionic functional group. The solubility of the polymer (A) in 100 g of water is preferably 2.0 g / 100 g or more, more preferably 5.0 g / 100 g or more, and further preferably 10.0 g / 100 g or more. ..
　第１構造単位（ａ１）は、（メタ）アクリルアミドに由来する構造単位であって、第１構造単位（ａ１）のための（メタ）アクリルアミドとしては、アクリルアミド、メタクリルアミド、及びこれらの混合物が挙げられる。 The first structural unit (a1) is a structural unit derived from (meth) acrylamide, and examples of the (meth) acrylamide for the first structural unit (a1) include acrylamide, methacrylamide, and mixtures thereof. Be done.
　第２構造単位（ａ２）は、水酸基及びエチレン性不飽和結合を有する化合物に由来する構造単位であって、水酸基を含む構造単位である。水酸基及びエチレン性不飽和結合を有する化合物としては、水酸基を１つのみ有する化合物であることが好ましい。第２構造単位（ａ２）は、例えば、水酸基を有する（メタ）アクリレート、ビニルアルコールに由来する構造単位が考えられる。第２構造単位（ａ２）は、水酸基を有する（メタ）アクリレートに由来する構造単位であることが好ましく、アルキル基のいずれかの水素原子が水酸基で置換されたアルキル（メタ）アクリレートであることがより好ましい。 The second structural unit (a2) is a structural unit derived from a compound having a hydroxyl group and an ethylenically unsaturated bond, and is a structural unit containing a hydroxyl group. As the compound having a hydroxyl group and an ethylenically unsaturated bond, a compound having only one hydroxyl group is preferable. As the second structural unit (a2), for example, a structural unit derived from (meth) acrylate having a hydroxyl group or vinyl alcohol can be considered. The second structural unit (a2) is preferably a structural unit derived from a (meth) acrylate having a hydroxyl group, and is an alkyl (meth) acrylate in which any hydrogen atom of an alkyl group is substituted with a hydroxyl group. More preferred.
　水酸基を有する（メタ）アクリレートの例としては、２－ヒドロキシエチル（メタ）アクリレート、２－ヒドロキシプロピル（メタ）アクリレート、ヒドロキシブチル（メタ）アクリレート、ヒドロキシペンチル（メタ）アクリレート、ヒドロキシヘキシル（メタ）アクリレート、ヒドロキシオクチル（メタ）アクリレート、ペンタエリスリトールトリ、ジ又はモノ（メタ）アクリレート、トリメチロールプロパンジ又はモノ（メタ）アクリレートなどのヒドロキシアルキル（メタ）アクリレート等が挙げられる。 Examples of (meth) acrylates having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, and hydroxyhexyl (meth) acrylate. , Hydroxyoctyl (meth) acrylate, pentaerythritol tri, di or mono (meth) acrylate, trimethylolpropane di or hydroxyalkyl (meth) acrylate such as mono (meth) acrylate and the like.
　これらの中でも、反応性の観点から、第２構造単位（ａ２）は、２－ヒドロキシエチル（メタ）アクリレート、２－ヒドロキシプロピル（メタ）アクリレートに由来する構造単位であることがより好ましく、２－ヒドロキシエチル（メタ）アクリレートであることがさらに好ましい。これらの中でも、剥離強度の向上及び熱収縮低減の観点から２－ヒドロキシエチルメタクリレートであることが特に好ましい。２－ヒドロキシエチルメタクリレートが特に効果を奏する理由は定かではないが、第１構造単位（ａ１）のための（メタ）アクリルアミドとの相乗効果によるものと推察される。（メタ）アクリルアミドとの重合性は、２－ヒドロキシエチルメタクリレートと、その他の化合物、例えば２－ヒドロキシエチルアクリレートとでは異なる。２－ヒドロキシエチルアクリレートと比較して、２－ヒドロキシエチルメタクリレートの方が、重合物の組成比率が均一でなく、重合物の一部がミクロ相分離を起こすため、より好適な水準での剥離強度の向上及び熱収縮低減を実現すると考えられる。 Among these, from the viewpoint of reactivity, the second structural unit (a2) is more preferably a structural unit derived from 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate, and 2-. It is more preferably hydroxyethyl (meth) acrylate. Among these, 2-hydroxyethyl methacrylate is particularly preferable from the viewpoint of improving peel strength and reducing heat shrinkage. The reason why 2-hydroxyethyl methacrylate is particularly effective is not clear, but it is presumed to be due to the synergistic effect with (meth) acrylamide for the first structural unit (a1). The polymerizable property with (meth) acrylamide is different between 2-hydroxyethyl methacrylate and other compounds such as 2-hydroxyethyl acrylate. Compared with 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate has a non-uniform composition ratio of the polymer, and a part of the polymer causes microphase separation, so that the peel strength at a more suitable level is used. It is considered that the improvement of the heat shrinkage and the reduction of heat shrinkage are realized.
　重合体（Ａ）における、第１構造単位（ａ１）の含有量と第２構造単位（ａ２）の含有量との質量比の値（（ａ１）の含有量／（ａ２）の含有量）は、５５．０／４５．０以上であり、６５．０／３５．０以上であることが好ましく、７５．０／２５．０以上であることがより好ましい。バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の耐熱性及び耐電解液性が向上するためである。 The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) (content of (a1) / content of (a2)) is It is 55.0 / 45.0 or more, preferably 65.0 / 35.0 or more, and more preferably 75.0 / 25.0 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved.
　重合体（Ａ）における、第１構造単位（ａ１）の含有量と第２構造単位（ａ２）の含有量との質量比の値（（ａ１）の含有量／（ａ２）の含有量）は、９５．０／５．０以下であり、９０．０／１０．０以下であることがより好ましく、８５．０／１５．０以下であることがさらに好ましい。重合体（Ａ）と、重合体（Ｂ）との相溶性を向上させるため、及び後述するスラリーの粘度の上昇を抑制し、塗工性を向上させるためである。 The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) (content of (a1) / content of (a2)) is , 95.0 / 5.0 or less, more preferably 90.0 / 10.0 or less, and even more preferably 85.0 / 15.0 or less. This is to improve the compatibility between the polymer (A) and the polymer (B), suppress the increase in the viscosity of the slurry described later, and improve the coatability.
　重合体（Ａ）には、他の化合物に由来する構造単位が含まれていてもよいが、重合体（Ａ）における、全構造単位中の第１構造単位（ａ１）及び第２構造単位（ａ２）の合計含有率は８０質量％以上であることが好ましく、９０質量％以上であることがより好ましく、１００質量％であることが特に好ましい。すなわち重合体（Ａ）は、前記第１構造単位（ａ１）と、前記第２構造単位（ａ２）のみからなる共重合体であることが特に好ましい。重合体（Ａ）による本発明の目的とする効果がより高まるためである。ここで、重合体（Ａ１）における構造単位には、その製造工程で用いられた重合開始剤、停止剤、連鎖移動剤等に由来する構造は含まれない。 The polymer (A) may contain structural units derived from other compounds, but the first structural unit (a1) and the second structural unit (a1) and the second structural unit (a1) among all the structural units in the polymer (A). The total content of a2) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. That is, it is particularly preferable that the polymer (A) is a copolymer composed of only the first structural unit (a1) and the second structural unit (a2). This is because the effect of the polymer (A), which is the object of the present invention, is further enhanced. Here, the structural unit in the polymer (A1) does not include a structure derived from a polymerization initiator, a terminator, a chain transfer agent, or the like used in the production process.
　重合体（Ａ）、または後述する非水系二次電池用セパレータバインダー組成物には、熱架橋性の構成成分（熱架橋性の構造単位又は熱架橋性の化合物）が含まれないことが好ましい。重合体（Ａ）を後述する非水系二次電池用セパレータスラリーに適用した場合に、フィラーに対する重合体の濡れ性が低下することによる分散性低下を抑制させるためである。また重合体（Ａ）を非水系二次電池用セパレータに適用した場合に、コーティング層中における重合体の硬化収縮等によるセパレータの寸法変化、及びコーティング層の基材に対する剥離強度の低下を抑制させるためである。 It is preferable that the polymer (A) or the separator binder composition for a non-aqueous secondary battery described later does not contain a heat-crosslinkable constituent component (heat-crosslinkable structural unit or heat-crosslinkable compound). This is to suppress a decrease in dispersibility due to a decrease in the wettability of the polymer with respect to the filler when the polymer (A) is applied to a separator slurry for a non-aqueous secondary battery described later. Further, when the polymer (A) is applied to a separator for a non-aqueous secondary battery, it suppresses a change in the size of the separator due to curing shrinkage of the polymer in the coating layer and a decrease in the peel strength of the coating layer with respect to the substrate. Because.
　＜熱架橋性の構成成分＞
　本実施形態に係る熱架橋性の構成成分は、熱架橋性の構造単位又は熱架橋性の化合物を含む。
　熱架橋性の構造単位としては、例えば、エポキシ基を有する単量体に由来する構造単位や、他官能（メタ）アクリレートに由来する構造単位等が挙げられる。これらの構造単位の由来となる単量体として例えば、グリシジルメタクリレート、エチレングリコールジメタクリレート等が挙げられる。なお、本実施形態においては、重合体（Ａ）の（メタ）アクリルアミドに由来する第１構造単位（ａ１）及び、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）は、熱架橋性の構造単位には該当しない。
　熱架橋性の化合物としては、架橋剤として使われる化合物が挙げられ、例えばカルボジイミド化合物、エポキシ化合物、イソシアネート化合物等が挙げられる。 <Heat-crosslinkable constituents>
The heat-crosslinkable constituent component according to the present embodiment contains a heat-crosslinkable structural unit or a heat-crosslinkable compound.
Examples of the heat-crosslinkable structural unit include a structural unit derived from a monomer having an epoxy group, a structural unit derived from another functional (meth) acrylate, and the like. Examples of the monomer from which these structural units are derived include glycidyl methacrylate and ethylene glycol dimethacrylate. In this embodiment, the first structural unit (a1) derived from (meth) acrylamide of the polymer (A) and the second structural unit (a2) derived from a compound having a hydroxyl group and an ethylenically unsaturated bond. Does not correspond to a thermally crosslinkable structural unit.
Examples of the heat-crosslinkable compound include compounds used as a cross-linking agent, and examples thereof include carbodiimide compounds, epoxy compounds, and isocyanate compounds.
　重合体（Ａ）の重量平均分子量は１００，０００以上であることが好ましく、３００，０００以上であることがより好ましく、３５０，０００以上であることがさらに好ましい。バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の耐電解液性、強度、基材に対する剥離強度が向上するためである。 The weight average molecular weight of the polymer (A) is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 350,000 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the electrolytic solution resistance, strength, and peel strength of the coating layer with respect to the substrate are improved.
　重合体（Ａ）の重量平均分子量は３，０００，０００以下であることが好ましく１，５００，０００以下であることがより好ましく、６５０，０００以下であることがさらに好ましい。後述するスラリーの粘度上昇を抑制し、スラリーの基材への塗工性が向上するためである。 The weight average molecular weight of the polymer (A) is preferably 3,000,000 or less, more preferably 1,500,000 or less, and even more preferably 650,000 or less. This is because it suppresses an increase in the viscosity of the slurry, which will be described later, and improves the coatability of the slurry on the substrate.
　重量平均分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いて測定されたプルラン換算値である。 The weight average molecular weight is a pullulan-equivalent value measured using gel permeation chromatography (GPC).
　重合体（Ａ）の合成方法として、例えば、（メタ）アクリルアミドと、水酸基及びエチレン性不飽和結合を有する化合物と、を含む単量体を水溶液重合することが挙げられる。合成に用いられるラジカル重合開始剤としては、例えば、過硫酸アンモニウム、過硫酸カリウム、過酸化水素、ｔ－ブチルハイドロパーオキサイド、アゾ化合物等が挙げられるが、これらに限られない。アゾ化合物としては、例えば、２，２’－アゾビス（２－メチルプロピオンアミジン）２塩酸塩が挙げられる。重合を水中で行う場合は、水溶性の重合開始剤を用いることが好ましい。また、必要に応じて、重合の際にラジカル重合開始剤と、還元剤とを併用して、レドックス重合してもよい。還元剤としては、重亜硫酸ナトリウム、ロンガリット、アスコルビン酸等が挙げられる。 Examples of the method for synthesizing the polymer (A) include aqueous solution polymerization of a monomer containing (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond. Examples of the radical polymerization initiator used in the synthesis include, but are not limited to, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and azo compounds. Examples of the azo compound include 2,2'-azobis (2-methylpropionamidine) dihydrochloride. When the polymerization is carried out in water, it is preferable to use a water-soluble polymerization initiator. Further, if necessary, a radical polymerization initiator and a reducing agent may be used in combination at the time of polymerization for redox polymerization. Examples of the reducing agent include sodium bisulfite, longalit, ascorbic acid and the like.
［１－２．重合体（Ｂ）］
　重合体（Ｂ）は、ポリビニルアルコール（ＰＶＡ）である。重合体（Ｂ）のけん化度は５５ｍｏｌ％以上であり、６５ｍｏｌ％以上であることが好ましく、７０ｍｏｌ％以上であることがより好ましく、８０ｍｏｌ％以上であることがさらに好ましい。バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の耐熱性及び耐電解液性が向上するためである。ここで、けん化度は、ＪＩＳ　Ｋ６７２６（１９９４）３．５項の測定方法（簡便法は用いない）によって測定される値である。 [1-2. Polymer (B)]
The polymer (B) is polyvinyl alcohol (PVA). The degree of saponification of the polymer (B) is 55 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved. Here, the saponification degree is a value measured by the measuring method according to JIS K6726 (1994) 3.5 (the simple method is not used).
　重合体（Ｂ）のけん化度は１００ｍｏｌ％であってもよいが、９９ｍｏｌ％以下であることが好ましく、９５ｍｏｌ％以下であることがより好ましく、９０ｍｏｌ％以下であることがさらに好ましい。重合体（Ｂ）と重合体（Ａ）との相溶性を確保するため、及び後述するスラリーの粘度の上昇を抑制し、基材への塗工性を良好にするためである。 The degree of saponification of the polymer (B) may be 100 mol%, but is preferably 99 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less. This is to ensure the compatibility between the polymer (B) and the polymer (A), suppress the increase in the viscosity of the slurry described later, and improve the coatability on the substrate.
　重合体（Ｂ）の重合度は、１００以上であることが好ましく、３００以上であることがより好ましく、１０００以上であることがさらに好ましく、１５００以上であることがさらに好ましい。バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の耐熱性及び耐電解液性が向上するためである。ここで、重合度は、ＪＩＳ　Ｋ６７２６（１９９４）３．７項の測定方法によって測定される値である。 The degree of polymerization of the polymer (B) is preferably 100 or more, more preferably 300 or more, further preferably 1000 or more, still more preferably 1500 or more. This is because when the binder is applied to a separator for a non-aqueous secondary battery, the heat resistance and electrolytic solution resistance of the coating layer are improved. Here, the degree of polymerization is a value measured by the measuring method according to JIS K6726 (1994) 3.7.
　重合体（Ｂ）の重合度は、５０００以下であることが好ましく、４０００以下であることがより好ましく、３０００以下であることがさらに好ましい。後述するスラリーの粘度の上昇を抑制し、基材への塗工性を良好にするためである。 The degree of polymerization of the polymer (B) is preferably 5000 or less, more preferably 4000 or less, and even more preferably 3000 or less. This is to suppress an increase in the viscosity of the slurry, which will be described later, and to improve the coatability on the substrate.
［１－３．重合体（Ａ）と重合体（Ｂ）との混合比率］
　非水系二次電池用セパレータバインダーにおける重合体（Ａ）の含有量と重合体（Ｂ）の含有量との質量比の値（重合体（Ａ）の含有量／重合体（Ｂ）の含有量）は、５５．０／４５．０以上であり、６５．０／３５．０以上であることが好ましく、７５．０／２５．０以上であることがさらに好ましい。バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の耐熱性が向上するためである。 [1-3. Mixing ratio of polymer (A) and polymer (B)]
The value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) in the separator binder for a non-aqueous secondary battery (content of polymer (A) / content of polymer (B)) ) Is 55.0 / 45.0 or more, preferably 65.0 / 35.0 or more, and more preferably 75.0 / 25.0 or more. This is because the heat resistance of the coating layer is improved when the binder is applied to the separator for a non-aqueous secondary battery.
　非水系二次電池用セパレータバインダーにおける重合体（Ａ）の含有量と重合体（Ｂ）の含有量との質量比の値は、９７．０／３．０以下であり、９３．０／７．０以下であることが好ましく、８５．０／１５．０以下であることがより好ましい。多孔質有機フィルムを基材とした場合に、スラリーの基材への濡れ性が向上するためである。また、バインダーを非水系二次電池用セパレータに適用した場合に、コーティング層の基材に対する剥離強度が向上するためである。 The value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) in the separator binder for a non-aqueous secondary battery is 97.0 / 3.0 or less, and 93.0 / 7 It is preferably 0.0 or less, and more preferably 85.0 / 15.0 or less. This is because when the porous organic film is used as the base material, the wettability of the slurry to the base material is improved. Further, when the binder is applied to the separator for a non-aqueous secondary battery, the peel strength of the coating layer with respect to the substrate is improved.
＜２．非水系二次電池用セパレータバインダー組成物＞
　本実施形態にかかる非水系二次電池用セパレータバインダー組成物は、上述した非水系二次電池用セパレータバインダーと、水性媒体とを含む。以下、非水系二次電池用セパレータバインダー組成物をバインダー組成物とすることもある。バインダー組成物において、重合体（Ａ）及び重合体（Ｂ）はいずれも水性媒体中に溶解していることが好ましい。本実施形態にかかるバインダー組成物は、これらの成分の他に、バインダーの作製のために用いた成分に由来する成分等を含んでもよく、本発明のバインダーに含まれる重合体以外の重合体、各種添加剤等を含んでもよい。 <2. Separator Binder Composition for Non-Aqueous Secondary Batteries>
The separator binder composition for a non-aqueous secondary battery according to the present embodiment includes the above-mentioned separator binder for a non-aqueous secondary battery and an aqueous medium. Hereinafter, a separator binder composition for a non-aqueous secondary battery may be used as a binder composition. In the binder composition, it is preferable that both the polymer (A) and the polymer (B) are dissolved in an aqueous medium. In addition to these components, the binder composition according to the present embodiment may contain components derived from the components used for producing the binder, and polymers other than the polymers contained in the binder of the present invention. It may contain various additives and the like.
　水性媒体としては水のみを用いるのが好ましいが、水と相溶する有機溶媒を水に混合してもよい。有機溶媒は大気圧での沸点が５０～１５０℃であることが好ましい。 It is preferable to use only water as the aqueous medium, but an organic solvent compatible with water may be mixed with water. The organic solvent preferably has a boiling point at atmospheric pressure of 50 to 150 ° C.
　水と相溶する有機溶媒の具体例としては、メタノール、エタノール、ｎ－プロピルアルコール、イソプロピルアルコール等のアルコール；ジプロピルエーテル、ジイソプロピルエーテル、ジブチルエーテル、ジイソブチルエーテル等の飽和脂肪族エーテル化合物；テトラヒドロフラン、テトラヒドロピラン、ジオキサン等の環状エーテル化合物；ギ酸ブチル、ギ酸アミル、酢酸エチル、酢酸プロピル、酢酸イソプロピル、酢酸ブチル等の有機酸エステル化合物；アセトン、エチルケトン、シクロヘキサノン等のケトン化合物等が挙げられる。 Specific examples of the organic solvent compatible with water include alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol; saturated aliphatic ether compounds such as dipropyl ether, diisopropyl ether, dibutyl ether and diisobutyl ether; tetrahydrofuran, Cyclic ether compounds such as tetrahydropyran and dioxane; organic acid ester compounds such as butyl formate, amyl formate, ethyl acetate, propyl acetate, isopropyl acetate and butyl acetate; ketone compounds such as acetone, ethyl ketone and cyclohexanone can be mentioned.
　水性媒体として、有機溶媒と水との混合溶媒を用いる場合は、水１００質量部に対する有機溶媒の含有量は特に限定されないが、１００質量部以下であることが好ましく、２０質量部以下であることがより好ましい。 When a mixed solvent of an organic solvent and water is used as the aqueous medium, the content of the organic solvent with respect to 100 parts by mass of water is not particularly limited, but is preferably 100 parts by mass or less, and is preferably 20 parts by mass or less. Is more preferable.
　バインダー組成物中の、重合体（Ａ）と重合体（Ｂ）との合計含有率は、仕様等に応じて適宜調整可能であり、特に限定されない。バインダー組成物中の、重合体（Ａ）と重合体（Ｂ）との合計含有率は、１．０質量％以上であることが好ましく、５．０質量％以上であることがより好ましく、１０．０質量％以上であることがさらに好ましい。後述するスラリーを作製する場合において、水性媒体等の成分を除去しなくても、バインダーの含有率を十分に保つことができるためである。 The total content of the polymer (A) and the polymer (B) in the binder composition can be appropriately adjusted according to the specifications and the like, and is not particularly limited. The total content of the polymer (A) and the polymer (B) in the binder composition is preferably 1.0% by mass or more, more preferably 5.0% by mass or more, and 10%. It is more preferably 0.0% by mass or more. This is because, in the case of producing the slurry described later, the content of the binder can be sufficiently maintained without removing the components such as the aqueous medium.
　バインダー組成物中の、重合体（Ａ）と重合体（Ｂ）との合計含有率は、７０質量％以下であることが好ましく、５０質量％以下であることがより好ましい。バインダー組成物の粘度が高くなりすぎることを抑制するためである。 The total content of the polymer (A) and the polymer (B) in the binder composition is preferably 70% by mass or less, more preferably 50% by mass or less. This is to prevent the viscosity of the binder composition from becoming too high.
＜３．非水系二次電池用セパレータスラリー＞
　本実施形態にかかる非水系二次電池用セパレータスラリーは、上述した非水系二次電池用セパレータバインダーと、フィラーと、水性媒体とを含む。非水系二次電池用セパレータバインダーについては上述したとおりである。以下、非水系二次電池用セパレータスラリーをスラリーとすることもある。本実施形態にかかるスラリーは、これらの成分の他に、バインダーの作製のために用いた成分に由来する成分等を含んでもよく、本発明のバインダー以外のバインダー等を含んでもよい。 <3. Separator slurry for non-aqueous secondary batteries ＞
The separator slurry for a non-aqueous secondary battery according to the present embodiment includes the above-mentioned separator binder for a non-aqueous secondary battery, a filler, and an aqueous medium. The separator binder for a non-aqueous secondary battery is as described above. Hereinafter, the separator slurry for a non-aqueous secondary battery may be used as a slurry. In addition to these components, the slurry according to the present embodiment may contain a component derived from the component used for producing the binder, or may contain a binder or the like other than the binder of the present invention.
　フィラーは、有機フィラー及び無機フィラーのいずれであってもよく、これらを併用してもよい。フィラーは無機フィラーを含むことが好ましく、無機フィラーからなることがより好ましい。 The filler may be either an organic filler or an inorganic filler, and these may be used in combination. The filler preferably contains an inorganic filler, and more preferably consists of an inorganic filler.
　無機フィラーとしては、炭酸カルシウム、タルク、クレー、カオリン、シリカ、ハイドロタルサイト、珪藻土、炭酸マグネシウム、炭酸バリウム、硫酸カルシウム、硫酸マグネシウム、硫酸バリウム、水酸化アルミニウム、水酸化マグネシウム、酸化カルシウム、酸化マグネシウム、酸化チタン、アルミナ、マイカ、ゼオライト、ガラス等が挙げられる。無機フィラーは、１種類の材質からなる粒子でもよく、２種類以上の材質の粒子を含んでもよい。また、無機フィラーは、異なる粒度分布を持つ粒子を混合して作製されてもよい。 Inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, hydrotalcite, diatomaceous soil, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide. , Titanium oxide, alumina, mica, zeolite, glass and the like. The inorganic filler may be particles made of one kind of material, or may contain particles made of two or more kinds of materials. Further, the inorganic filler may be prepared by mixing particles having different particle size distributions.
　フィラーは、金属酸化物粒子を含むことがより好ましく、アルミナ粒子を含むことがさらに好ましい。アルミナ粒子は本実施形態にかかるバインダーとの親和性が優れており、混錬時の分散性が良く、低粘度で塗工性が良好なスラリーが得られるためである。 The filler preferably contains metal oxide particles, and more preferably contains alumina particles. This is because the alumina particles have an excellent affinity with the binder according to the present embodiment, have good dispersibility during kneading, and can obtain a slurry having a low viscosity and good coatability.
　フィラーを構成する粒子の平均粒径は３μｍ以下であることが好ましく、１μｍ以下であることがさらに好ましい。ここでいう平均粒径は、ＳＥＭ（走査電子顕微鏡）観察より求めた一次粒径の数平均値である。具体的には、ＳＥＭに映ったフィラーの粒子１００個をランダムに選択し、各粒子における最も長い寸法を測定し、これらの測定された寸法の平均値がフィラーの平均粒径である。 The average particle size of the particles constituting the filler is preferably 3 μm or less, and more preferably 1 μm or less. The average particle size referred to here is a number average value of the primary particle size obtained by SEM (scanning electron microscope) observation. Specifically, 100 particles of the filler reflected in the SEM are randomly selected, the longest dimension of each particle is measured, and the average value of these measured dimensions is the average particle size of the filler.
　スラリーにおけるバインダーの含有量とフィラーの含有量との質量比（バインダーの含有量／フィラーの含有量）の値は、１．０／９９．０以上であることが好ましく、２．０／９８．０以上であることがより好ましく、４．０／９６．０以上であることがさらに好ましい。スラリーから作製されたコーティング層の基材に対する剥離強度を向上させるため、及びコーティング層にフィラー粒子を十分に固定するためである。また、コーティング層の耐熱性を向上させるためでもある。 The value of the mass ratio (binder content / filler content) between the binder content and the filler content in the slurry is preferably 1.0 / 99.0 or more, and 2.0 / 98. It is more preferably 0 or more, and further preferably 4.0 / 96.0 or more. This is to improve the peel strength of the coating layer made from the slurry to the substrate and to sufficiently fix the filler particles to the coating layer. It is also for improving the heat resistance of the coating layer.
　スラリーにおけるバインダーの含有量とフィラーの含有量との質量比の値は、１５．０／８５．０以下であることが好ましく、１０．０／９０．０以下であることがより好ましく、７．０／９３．０以下であることがさらに好ましい。後述するセパレータにおいて、透気度及びイオンの透過性を十分に保ち、良好な負荷特性の電池を得るためである。 The value of the mass ratio of the content of the binder to the content of the filler in the slurry is preferably 15.0 / 85.0 or less, more preferably 10.0 / 90.0 or less, and 7. It is more preferably 0 / 93.0 or less. This is to obtain a battery having good load characteristics by sufficiently maintaining the air permeability and the permeability of ions in the separator described later.
　水性媒体としては水のみを用いるのが好ましいが、大気圧での沸点が５０～１５０℃かつ水と相溶する有機溶媒と水との混合溶媒を用いてもよい。有機溶媒の例については、バインダー組成物の項にて例示した化合物と同様である。水性媒体として、有機溶媒と水との混合溶媒を用いる場合は、水１００質量部に対する有機溶媒の含有量は特に限定されないが、１００質量部以下であることが好ましく、２０質量部以下であることがより好ましい。 It is preferable to use only water as the aqueous medium, but a mixed solvent of water and an organic solvent having a boiling point at atmospheric pressure of 50 to 150 ° C. and compatible with water may be used. Examples of the organic solvent are the same as those of the compound exemplified in the section of the binder composition. When a mixed solvent of an organic solvent and water is used as the aqueous medium, the content of the organic solvent with respect to 100 parts by mass of water is not particularly limited, but is preferably 100 parts by mass or less, and is preferably 20 parts by mass or less. Is more preferable.
　スラリー中の水性媒体の含有率は、仕様等に応じて適宜調整可能であり、限定されない。スラリー中の水性媒体の含有率は、８０質量％以下であることが好ましく、７０質量％以下であることがより好ましく、６０質量％以下であることがさらに好ましい。スラリーを基材に塗布する場合に、より少ないスラリーの量で十分な厚さのコーティング層を形成できるためである。 The content of the aqueous medium in the slurry can be appropriately adjusted according to the specifications and the like, and is not limited. The content of the aqueous medium in the slurry is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less. This is because when the slurry is applied to the substrate, a coating layer having a sufficient thickness can be formed with a smaller amount of slurry.
　スラリー中の水性媒体の含有率は、２０質量％以上であることが好ましく、３０質量％以上であることがより好ましく、４０質量％以上であることがさらに好ましい。スラリーの粘度を塗工に適した範囲とするためである。 The content of the aqueous medium in the slurry is preferably 20% by mass or more, more preferably 30% by mass or more, and further preferably 40% by mass or more. This is to keep the viscosity of the slurry within a range suitable for coating.
＜４．非水系二次電池用セパレータスラリーの製造方法＞
　スラリーの製造方法としては、例えば、重合体（Ａ）と重合体（Ｂ）とを水性媒体中で混合し、バインダー組成物を作製した後にフィラーを混合、分散させる第１の方法；フィラーと重合体（Ａ）とを水性媒体中で混合し、フィラーを分散させた後に重合体（Ｂ）を加える第２の方法；フィラーと重合体（Ｂ）とを水性媒体中で混合し、フィラーを分散させた後に重合体（Ａ）を加える第３の方法；フィラーを水性媒体中に分散させた後に重合体（Ａ）及び重合体（Ｂ）を加える第４の方法；フィラーと重合体（Ａ）と重合体（Ｂ）とを水性媒体中で同時に混合し、フィラーを分散させる第５の方法などがあるが、特に限定されない。 <4. Manufacturing method of separator slurry for non-aqueous secondary batteries>
As a method for producing a slurry, for example, a first method in which a polymer (A) and a polymer (B) are mixed in an aqueous medium to prepare a binder composition, and then a filler is mixed and dispersed; a filler and a weight are used. A second method in which the coalescence (A) is mixed in an aqueous medium, the filler is dispersed, and then the polymer (B) is added; the filler and the polymer (B) are mixed in the aqueous medium, and the filler is dispersed. A third method of adding the polymer (A) after the mixture; a fourth method of adding the polymer (A) and the polymer (B) after dispersing the filler in an aqueous medium; the filler and the polymer (A). There is a fifth method of simultaneously mixing the polymer (B) and the polymer (B) in an aqueous medium to disperse the filler, but the method is not particularly limited.
　これらの方法のうち、後述するコーティング層の剥離強度を向上させるためには第２の方法が好ましい。一方で、バインダー組成物をあらかじめ準備しておく第１の方法は、スラリーの製造コスト及び材料の管理コストを削減するために好ましい場合がある。 Of these methods, the second method is preferable in order to improve the peel strength of the coating layer described later. On the other hand, the first method of preparing the binder composition in advance may be preferable in order to reduce the production cost of the slurry and the management cost of the material.
＜５．非水系二次電池用セパレータ＞
　本実施形態にかかる非水系二次電池用セパレータは、多孔質フィルムである基材と、基材の表面に形成されたコーティング層とを備える。本実施形態にかかるコーティング層は、基材の面のうち、正極に対向する面、及び負極に対向する面のいずれに形成されていてもよく、両方の面に形成されていてもよい。非水系二次電池用セパレータは、例えば、接着層、保護層等を備えてもよい。以下、本実施形態にかかる非水系二次電池用セパレータを、セパレータとすることもある。 <5. Separator for non-aqueous secondary batteries ＞
The separator for a non-aqueous secondary battery according to the present embodiment includes a base material which is a porous film and a coating layer formed on the surface of the base material. The coating layer according to the present embodiment may be formed on either of the surfaces of the base material facing the positive electrode and the surface facing the negative electrode, or may be formed on both surfaces. The separator for a non-aqueous secondary battery may include, for example, an adhesive layer, a protective layer, and the like. Hereinafter, the separator for a non-aqueous secondary battery according to the present embodiment may be referred to as a separator.
　基材の材質としては、例えば、ポリオレフィン等の熱可塑性樹脂、ビスコースレーヨン及びや天然セルロース等の抄紙、セルロース及びポリエステル等の繊維を抄紙して得られる混抄紙、電解紙、クラフト紙、マニラ紙、マニラ麻シート、ガラス繊維、多孔質ポリエステル、アラミド繊維、ポリブチレンテレフタレート不織布、パラ系アラミド、フッ化ビニリデン、テトラフルオロエチレン、フッ化ビニリデンと６フッ化プロピレンとの共重合体、フッ素ゴム等の含フッ素樹脂等の不織布または多孔膜が挙げられる。 Examples of the material of the base material include thermoplastic resins such as polyolefin, papermaking such as biscorayon and natural cellulose, mixed papermaking obtained by papermaking fibers such as cellulose and polyester, electrolytic paper, kraft paper, and Manila paper. , Manila hemp sheet, glass fiber, porous polyester, aramid fiber, polybutylene terephthalate non-woven fabric, para-aramid, vinylidene fluoride, tetrafluoroethylene, copolymer of vinylidene fluoride and propylene hexafluoride, fluororubber, etc. Examples thereof include a non-woven fabric such as a fluororesin or a porous film.
　基材の材質としては、ポリオレフィンであることが好ましい。ポリオレフィンとしては、例えば、エチレン、プロピレン、１－ブテン、４－メチル－１－ペンテン、１－ヘキセン等の単独重合体又は共重合体が挙げられる。これらのうちエチレンを主体とする共重合体又はエチレンの単独重合体が好ましく、エチレンの単独重合体、即ちポリエチレンがより好ましい。 The material of the base material is preferably polyolefin. Examples of the polyolefin include homopolymers or copolymers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Of these, a copolymer mainly composed of ethylene or a homopolymer of ethylene is preferable, and a homopolymer of ethylene, that is, polyethylene is more preferable.
　基材の厚みは、５～５０μｍであることが好ましく、５～３０μｍであることがより好ましい。基材は、市販の多孔質フィルムを用いてもよい。 The thickness of the base material is preferably 5 to 50 μm, more preferably 5 to 30 μm. As the base material, a commercially available porous film may be used.
　コーティング層は、上述した非水系二次電池用セパレータバインダーと、上述したフィラーとを含む。コーティング層の厚みは特に限定されないが、１０μｍ以下であることが好ましい。セパレータを備える非水電解液二次電池の負荷特性を良好にするためである。 The coating layer contains the above-mentioned separator binder for a non-aqueous secondary battery and the above-mentioned filler. The thickness of the coating layer is not particularly limited, but is preferably 10 μm or less. This is to improve the load characteristics of the non-aqueous electrolyte secondary battery provided with the separator.
＜６．非水系二次電池用セパレータの製造方法＞
　非水系二次電池用セパレータの製造方法は、特に限定されないが、例えば、本実施形態にかかるスラリーを基材の表面に塗布し、塗布されたスラリーを乾燥させる方法等が挙げられる。スラリーを基材の表面に塗布する前に、予め基材にコロナ処理等の表面処理を施してもよい。 <6. Manufacturing method of separator for non-aqueous secondary battery>
The method for producing the separator for a non-aqueous secondary battery is not particularly limited, and examples thereof include a method in which the slurry according to the present embodiment is applied to the surface of the base material and the applied slurry is dried. Before applying the slurry to the surface of the base material, the base material may be subjected to surface treatment such as corona treatment in advance.
　スラリーを、基材の表面に塗布する方法は、例えば、ドクターブレードによる塗布等の工業的に通常行われる方法が挙げられる。コーティング層の厚みは、スラリーの塗布量、スラリー中の固形分の濃度等を調節することによって制御することができる。 Examples of the method of applying the slurry to the surface of the base material include industrially usual methods such as application with a doctor blade. The thickness of the coating layer can be controlled by adjusting the coating amount of the slurry, the concentration of the solid content in the slurry, and the like.
　基材に塗布されたスラリーを乾燥させることで、スラリーから揮発分が除去され、コーティング層が形成される。乾燥は、例えば、乾燥炉等の加熱装置を用いる方法、減圧装置を用いる方法、あるいは加熱及び減圧の両方を行う方法等が挙げられる。加熱、減圧、及び乾燥時間等の条件は、基材の材質及び形態、揮発分に含まれる溶剤の種類等に応じて適宜選択でき、例えば、乾燥温度は、基材の融点またはガラス転移点以下の範囲にすることが好ましい。具体的にはスラリーの乾燥温度は１００℃以下であることが好ましく、８０℃以下であることがより好ましく、７０℃以下であることがさらに好ましい。また、生産性の観点から、５０℃以上であることが好ましい。また、減圧条件としては、生産性を考慮しつつ、コーティング層に気泡等が発生しない程度に設定することが好ましい。 By drying the slurry applied to the base material, volatile components are removed from the slurry and a coating layer is formed. Examples of the drying include a method using a heating device such as a drying furnace, a method using a depressurizing device, a method of performing both heating and depressurization, and the like. Conditions such as heating, depressurization, and drying time can be appropriately selected according to the material and form of the base material, the type of solvent contained in the volatile matter, etc. For example, the drying temperature is equal to or lower than the melting point or glass transition point of the base material. It is preferable to set it in the range of. Specifically, the drying temperature of the slurry is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and even more preferably 70 ° C. or lower. Further, from the viewpoint of productivity, the temperature is preferably 50 ° C. or higher. Further, it is preferable to set the depressurization condition to such an extent that bubbles and the like are not generated in the coating layer while considering productivity.
　より具体的には、基材としてポリプロピレン等の熱可塑性樹脂を含む多孔膜フィルムを用いる場合の乾燥条件としては、５５～６５℃で２～１０分間乾燥することが好ましく、６０℃で５分間乾燥することがより好ましい。多孔質フィルムに含まれる熱可塑性樹脂の軟化又は溶融により多孔質フィルムにおける孔がつぶれることを抑制するためである。　 More specifically, when a porous membrane film containing a thermoplastic resin such as polypropylene is used as the base material, the drying conditions are preferably 55 to 65 ° C. for 2 to 10 minutes, and 60 ° C. for 5 minutes. It is more preferable to do so. This is to prevent the pores in the porous film from being crushed due to softening or melting of the thermoplastic resin contained in the porous film. It was
＜７．非水系二次電池＞
　本実施形態の一例にかかる非水系二次電池は、正極と、負極と、電解液と、セパレータと、が外装体に収容された構成を有する。セパレータは、正極と負極との間に配される。正極の正極活物質層と、負極の負極活物質層と、がセパレータを介して対向するように配されることが好ましい。セパレータは上述した構成を有する。ここでは、非水系二次電池がリチウムイオン二次電池である場合を例として説明するが、非水系二次電池はこれに限定されず、例えば、カリウムイオン二次電池、ナトリウムイオン二次電池等でもよい。 <7. Non-water-based secondary battery ＞
The non-aqueous secondary battery according to an example of the present embodiment has a configuration in which a positive electrode, a negative electrode, an electrolytic solution, and a separator are housed in an exterior body. The separator is arranged between the positive electrode and the negative electrode. It is preferable that the positive electrode active material layer of the positive electrode and the negative electrode active material layer of the negative electrode are arranged so as to face each other with the separator interposed therebetween. The separator has the above-mentioned configuration. Here, a case where the non-aqueous secondary battery is a lithium ion secondary battery will be described as an example, but the non-aqueous secondary battery is not limited to this, and for example, a potassium ion secondary battery, a sodium ion secondary battery, etc. But it may be.
〔７－１．電極（正極及び負極）〕
　以下、正極及び負極を区別せずに説明する場合は、電極とすることがある。電極は、集電体と、集電体上に形成された電極活物質層とを備える。 [7-1. Electrodes (positive electrode and negative electrode)]
Hereinafter, when the positive electrode and the negative electrode are described without distinction, they may be referred to as electrodes. The electrode includes a current collector and an electrode active material layer formed on the current collector.
　集電体としては金属箔が用いられ、リチウムイオン二次電池の場合、正極としてはアルミニウム箔、負極としては銅箔が好ましく用いられる。集電体の形状としては、例えば、箔、平板状、メッシュ状、ネット状、ラス状、パンチング状若しくはエンボス状であるもの又はこれらを組み合わせたもの（例えば、メッシュ状平板など）等が挙げられる。集電体は、その表面にエッチング処理により凹凸が形成されてもよい。 A metal foil is used as the current collector, and in the case of a lithium ion secondary battery, an aluminum foil is preferably used as the positive electrode and a copper foil is preferably used as the negative electrode. Examples of the shape of the current collector include a foil, a flat plate, a mesh, a net, a lath, a punching shape, an embossed shape, or a combination thereof (for example, a mesh flat plate). .. The surface of the current collector may have irregularities formed by etching.
　電極活物質層は、電極活物質が電極バインダーを介して集電体に決着された構成を有することが好ましい。また、電極活物質層は、導電助剤等の添加剤が含まれていてもよい。電極活物質は、電荷キャリアとなるイオン（リチウムイオン二次電池の場合はリチウムイオン）を吸蔵及び放出することが可能で、正極活物質は負極活物質よりも電気化学的に貴な材料を用いる。 It is preferable that the electrode active material layer has a structure in which the electrode active material is fixed to the current collector via the electrode binder. Further, the electrode active material layer may contain an additive such as a conductive auxiliary agent. The electrode active material can store and release ions that become charge carriers (lithium ions in the case of a lithium ion secondary battery), and the positive electrode active material uses a material that is electrochemically more precious than the negative electrode active material. ..
　正極活物質としては、Ｎｉ－Ｃｏ－Ｍｎ系のリチウム複合酸化物、Ｎｉ－Ｍｎ－Ａｌ系のリチウム複合酸化物、Ｎｉ－Ｃｏ－Ａｌ系のリチウム複合酸化物などのニッケルを含むリチウム複合酸化物、コバルト酸リチウム（ＬｉＣｏＯ２）、スピネル型マンガン酸リチウム（ＬｉＭｎ２Ｏ４）、オリビン型燐酸鉄リチウム、ＴｉＳ２、ＭｎＯ２、ＭｏＯ３、Ｖ２Ｏ５等のカルコゲン化合物等が挙げられる。正極活物質として、これらの物質は１種で用いてもよく、あるいは２種類以上を組み合わせて用いてもよい。 As the positive electrode active material, a lithium composite oxide containing nickel such as a Ni—Co—Mn-based lithium composite oxide, a Ni—Mn—Al based lithium composite oxide, and a Ni—Co—Al based lithium composite oxide. , Lithium cobalt oxide (LiCoO 2 ), spinel-type lithium manganate (LiMn 2 O 4 ), olivine-type lithium iron phosphate, TiS 2 , MnO 2 , MoO 3 , V2 O 5 , and the like. As the positive electrode active material, these substances may be used alone or in combination of two or more.
　負極活物質としては、珪素、珪素酸化物（ＳｉＯ２等）、炭素質物質、金属複合酸化物等が挙げられ、好ましくは、アモルファスカーボン、人造黒鉛、天然黒鉛等の炭素質材料；ＡｘＭｙＯｚ（式中、ＡはＬｉ、ＭはＣｏ、Ｎｉ、Ａｌ、Ｓｎ及びＭｎから選択される少なくとも一種、Ｏは酸素原子を表し、ｘ、ｙ、ｚはそれぞれ１．１０≧ｘ≧０．０５、４．００≧ｙ≧０．８５、５．００≧ｚ≧１．５である。）で表される複合金属酸化物、及びその他の金属酸化物等が挙げられる。負極活物質は、１種類の物質からなる構成でもよく、２種類以上の物質を含む構成でもよい。 Examples of the negative electrode active material include silicon, silicon oxide (SiO 2 and the like), carbonaceous substances, metal composite oxides and the like, and preferably carbonaceous materials such as amorphous carbon, artificial graphite and natural graphite; A x M. y O z (In the formula, A is Li, M is at least one selected from Co, Ni, Al, Sn and Mn, O is an oxygen atom, and x, y and z are 1.10 ≧ x ≧ 0, respectively. .05, 4.00 ≧ y ≧ 0.85, 5.00 ≧ z ≧ 1.5), and other metal oxides and the like. The negative electrode active material may be composed of one kind of substance or may be composed of two or more kinds of substances.
　電極バインダーには、本実施形態にかかるバインダーを用いてもよく、その他の樹脂等を用いてもよい。電極バインダーとして用いられる材料は、本実施形態で説明した重合体（Ａ）及び重合体（Ｂ）の他に、（メタ）アクリル酸エステル及び（メタ）アクリル酸を含むモノマーを共重合させたアクリル系共重合体、（メタ）アクリル酸塩とＮ－ビニルアセトアミドとの共重合体、スチレン－ブタジエンゴム、ポリフッ化ビニリデン等が挙げられるが、これらに限られない。また、電極バインダーには、複数の種類の材料が含まれていてもよい。 As the electrode binder, the binder according to this embodiment may be used, or other resin or the like may be used. The material used as the electrode binder is an acrylic obtained by copolymerizing a monomer containing (meth) acrylic acid ester and (meth) acrylic acid in addition to the polymer (A) and the polymer (B) described in the present embodiment. Examples thereof include, but are not limited to, a system copolymer, a copolymer of (meth) acrylate and N-vinylacetamide, styrene-butadiene rubber, and polyvinylidene fluoride. Further, the electrode binder may contain a plurality of types of materials.
　導電助剤としては、カーボンブラック、炭素繊維等を用いることが好ましい。カーボンブラックとしては、ファーネスブラック、アセチレンブラック、デンカブラック（登録商標）（デンカ株式会社製）、ケッチェンブラック（登録商標）（ケッチェンブラックインターナショナル株式会社製）等が挙げられる。炭素繊維は、カーボンナノチューブ、カーボンナノファイバー等が挙げられ、カーボンナノチューブとしては、気相法炭素繊維であるＶＧＣＦ（登録商標、昭和電工株式会社製）が好ましい例として挙げられる。 It is preferable to use carbon black, carbon fiber, or the like as the conductive auxiliary agent. Examples of carbon black include furnace black, acetylene black, denka black (registered trademark) (manufactured by Denka Co., Ltd.), and Ketjen black (registered trademark) (manufactured by Ketjen Black International Co., Ltd.). Examples of the carbon fiber include carbon nanotubes and carbon nanofibers, and examples of the carbon nanotube include VGCF (registered trademark, manufactured by Showa Denko Co., Ltd.), which is a vapor phase carbon fiber.
〔７－２．電解液〕
　電解液としては、電解質を有機溶媒に溶解させた溶液、イオン液体が挙げられるが、溶液であることが好ましい。 [7-2. Electrolyte]
Examples of the electrolytic solution include a solution in which an electrolyte is dissolved in an organic solvent and an ionic liquid, and a solution is preferable.
　電解質としては、アルカリ金属塩を用いることができ、電極活物質の種類等に応じ適宜選択できる。電解質としては、例えば、ＬｉＣｌＯ４、ＬｉＢＦ６、ＬｉＰＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＢ１０Ｃｌ１０、ＬｉＡｌＣｌ４、ＬｉＣｌ、ＬｉＢｒ、ＬｉＢ（Ｃ２Ｈ５）４、ＣＦ３ＳＯ３Ｌｉ、ＣＨ３ＳＯ３Ｌｉ、ＬｉＣＦ３ＳＯ３、ＬｉＣ４Ｆ９ＳＯ３、Ｌｉ（ＣＦ３ＳＯ２）２Ｎ、脂肪族カルボン酸リチウム等が挙げられる。また、電解質として、その他のアルカリ金属塩を用いることもできる。 As the electrolyte, an alkali metal salt can be used and can be appropriately selected depending on the type of the electrode active material and the like. Examples of the electrolyte include LiClO 4 , LiBF 6 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiB 10 Cl 10 , LiAlCl 4 , LiCl, LiBr, LiB (C2H 5 ). 4 , CF 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3 , LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ) 2 N, lithium aliphatic carboxylate and the like can be mentioned. Further, other alkali metal salts can also be used as the electrolyte.
　電解質を溶解する有機溶媒としては、特に限定されないが、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ジエチルカーボネート（ＤＥＣ）、メチルエチルカーボネート（ＭＥＣ）、ジメチルカーボネート（ＤＭＣ）、フルオロエチレンカーボネート（ＦＥＣ）、ビニレンカーボネート（ＶＣ）等の炭酸エステル化合物、アセトニトリル等のニトリル化合物、酢酸エチル、酢酸プロピル、プロピオン酸メチル、プロピオン酸エチル、プロピオン酸プロピルなどのカルボン酸エステルが挙げられる。これらの有機溶媒は、１種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。中でも、直鎖カーボネート系溶媒を組合せたものを用いることが好ましい。直鎖カーボネート系溶媒としては炭酸ジエチル、炭酸ジメチル、炭酸エチルメチルが挙げられる。 The organic solvent that dissolves the electrolyte is not particularly limited, and is, for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), and fluoroethylene carbonate. Examples thereof include carbonic acid ester compounds such as (FEC) and vinylene carbonate (VC), nitrile compounds such as acetonitrile, and carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate and propyl propionate. These organic solvents may be used alone or in combination of two or more. Above all, it is preferable to use a combination of a linear carbonate solvent. Examples of the linear carbonate-based solvent include diethyl carbonate, dimethyl carbonate, and ethylmethyl carbonate.
〔７－３．外装体〕
　外装体としては、例えばアルミニウム箔と樹脂フィルムとのラミネート材等を適宜使用できるが、これに限られない。電池の形状は、コイン型、ボタン型、シート型、円筒型、角型、扁平型等、いずれの形状であってもよい。 [7-3. Exterior]
As the exterior body, for example, a laminated material of an aluminum foil and a resin film can be appropriately used, but the exterior body is not limited to this. The shape of the battery may be any shape such as a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.
　以下、実施例及び比較例によって本発明をより具体的に説明するが、本発明はこれらの実施例によっては制限されない。なお、本実施形態において、各単量体の略称は、それぞれ以下の化合物を表す。
・Ａｍ：アクリルアミド
・ＨＥＡ：２－ヒドロキシエチルアクリレート
・ＨＥＭＡ：２－ヒドロキシエチルメタクリレート Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In this embodiment, the abbreviations for each monomer represent the following compounds.
-Am: Acrylamide-HEA: 2-Hydroxyethyl acrylate-HEMA: 2-Hydroxyethyl methacrylate
＜１．重合体（Ａ）の水溶液、及び重合体（ＣＡ）の水溶液の作製＞
〔１－１．重合体（Ａ）、重合体（ＣＡ－１）及び重合体（ＣＡ－２）の水溶液の作製〕
　表１に示すように、重合体（Ａ－１）～（Ａ－６）、及び重合体（ＣＡ－１）、（ＣＡ－２）を合成した。合成のための、後述する条件、生成物の測定結果、重合体の構成については、表１に示す。 <1. Preparation of Aqueous Solution of Polymer (A) and Aqueous Solution of Polymer (CA)>
[1-1. Preparation of Aqueous Solution of Polymer (A), Polymer (CA-1) and Polymer (CA-2)]
As shown in Table 1, polymers (A-1) to (A-6), and polymers (CA-1) and (CA-2) were synthesized. Table 1 shows the conditions described later, the measurement results of the product, and the composition of the polymer for the synthesis.
　以下の説明において、「重合体（Ａ－１）～重合体（Ａ－６）」のいずれかを「重合体（Ａ）」とすることもある。以下の説明において、「重合体（ＣＡ－１）、重合体（ＣＡ－２）、または重合体（ＣＡ－３）（後述する）」を「重合体（ＣＡ）」とすることもある。 In the following description, any one of "polymer (A-1) to polymer (A-6)" may be referred to as "polymer (A)". In the following description, "polymer (CA-1), polymer (CA-2), or polymer (CA-3) (described later)" may be referred to as "polymer (CA)".
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
［工程１］
　各々の重合体の合成において、攪拌装置、温度計及びコンデンサーを備えた反応容器中にイオン交換水を、表１の工程１の欄に示す量で投入し、窒素雰囲気下で撹拌しながら８０℃まで昇温した。 [Step 1]
In the synthesis of each polymer, ion-exchanged water was poured into a reaction vessel equipped with a stirrer, a thermometer and a condenser in the amount shown in the column of step 1 in Table 1, and the temperature was 80 ° C. while stirring in a nitrogen atmosphere. The temperature was raised to.
［工程２］
　８０℃になったところで開始剤として、過硫酸アンモニウム０．５０ｇをイオン交換水６．６gに溶解した開始剤水溶液を一括で投入した。開始剤水溶液の投入と同時に、各々の重合体の合成において、表１の工程２の欄に示す量で、５０質量％アクリルアミド水溶液、２－ヒドロキシエチルアクリレート、及びイオン交換水を滴下し始め、滴下は３０分かけて行った。その後、８０℃で２時間反応を行った。なお、表１におけるＡｍ単独量は、用いられたアクリルアミド水溶液中に含まれる、アクリルアミドの質量（ｇ）である。 [Step 2]
When the temperature reached 80 ° C., an initiator aqueous solution prepared by dissolving 0.50 g of ammonium persulfate in 6.6 g of ion-exchanged water was added in a batch. Simultaneously with the addition of the initiator aqueous solution, in the synthesis of each polymer, 50% by mass acrylamide aqueous solution, 2-hydroxyethyl acrylate, and ion-exchanged water were started to be dropped in the amounts shown in the column of step 2 in Table 1, and then dropped. Went for 30 minutes. Then, the reaction was carried out at 80 ° C. for 2 hours. The amount of Am alone in Table 1 is the mass (g) of acrylamide contained in the aqueous acrylamide solution used.
［工程３］
　その後、各々の重合体の合成において、表１の工程３の欄に示す量で、イオン交換水を投入した。 [Step 3]
Then, in the synthesis of each polymer, ion-exchanged water was added in the amount shown in the column of step 3 in Table 1.
　以上の工程で得られた、生成物の水溶液について、水溶液の不揮発分、粘度、ｐＨ、及び重合体の重量平均分子量を以下に述べる方法で測定し、測定結果を表１に示した。 Regarding the aqueous solution of the product obtained in the above steps, the non-volatile content, viscosity, pH, and weight average molecular weight of the polymer were measured by the methods described below, and the measurement results are shown in Table 1.
〔１－２．重合体（ＣＡ－３）の水溶液の作製〕
　攪拌装置、温度計及びコンデンサーを備えた反応容器中にイオン交換水９７０．０ｇ、重合体（ＣＡ－３）としてカルボキシメチルセルロースナトリウム塩（日本製紙株式会社製、サンローズ（登録商標）ＭＡＣ　３５０ＨＣ）３０．０ｇを投入し、窒素雰囲気下で撹拌しながら８０℃まで昇温した。８０℃で３時間撹拌を行い、カルボキシメチルセルロースナトリウム塩を溶解し、重合体（ＣＡ－３）の３．０質量％水溶液を作製した。 [1-2. Preparation of aqueous solution of polymer (CA-3)]
970.0 g of ion-exchanged water in a reaction vessel equipped with a stirrer, thermometer and condenser, carboxymethyl cellulose sodium salt as a polymer (CA-3) (Sunrose (registered trademark) MAC 350HC, manufactured by Nippon Paper Co., Ltd.) 30 9.0 g was added, and the temperature was raised to 80 ° C. while stirring in a nitrogen atmosphere. The mixture was stirred at 80 ° C. for 3 hours to dissolve the sodium carboxymethyl cellulose salt to prepare a 3.0% by mass aqueous solution of the polymer (CA-3).
〔１－３．重合体（Ａ）及び重合体（ＣＡ）並びにそれらの水溶液の各種測定〕
［不揮発分の測定］
　重合体（Ａ）の水溶液、及び重合体（ＣＡ）の水溶液をそれぞれ、直径５ｃｍのアルミ皿に１ｇ秤量し、１気圧（１０１３ｈＰａ）で、乾燥器内で空気を循環させながら１３０℃で１時間乾燥させ、残った成分の質量を測定した。乾燥前のバインダー組成物の質量（１ｇ）に対する、乾燥後に残った上記成分の質量割合（質量％）を不揮発分として算出した。 [1-3. Various measurements of polymer (A) and polymer (CA) and their aqueous solutions]
[Measurement of non-volatile content]
Weigh 1 g of each of the aqueous solution of the polymer (A) and the aqueous solution of the polymer (CA) in an aluminum dish having a diameter of 5 cm, and at 1 atm (1013 hPa), circulate the air in the dryer for 1 hour at 130 ° C. After drying, the mass of the remaining components was measured. The mass ratio (mass%) of the above components remaining after drying to the mass (1 g) of the binder composition before drying was calculated as the non-volatile content.
［粘度の測定］
　重合体（Ａ）の水溶液、及び重合体（ＣＡ）の水溶液について、それぞれ、ブルックフィールド型粘度計（東機産業製）により、液温２３℃、回転数１０ｒｐｍ、Ｎｏ．３、Ｎｏ．４及びＮｏ．５のうちいずれかのローターを用いて粘度を測定した。なお、ローターは、それぞれの水溶液の粘度に応じて選択する。 [Measurement of viscosity]
The aqueous solution of the polymer (A) and the aqueous solution of the polymer (CA) were measured by a Brookfield viscometer (manufactured by Toki Sangyo Co., Ltd.) at a liquid temperature of 23 ° C. and a rotation speed of 10 rpm. 3, No. 4 and No. Viscosity was measured using any of the rotors of 5. The rotor is selected according to the viscosity of each aqueous solution.
［ｐＨの測定］
　重合体（Ａ）の水溶液、及び重合体（ＣＡ）の水溶液について、それぞれ、ｐＨを、液温２３℃の状態でｐＨメーター（東亜ディーケーケー製）を用いて計測した。 [Measurement of pH]
The pH of each of the aqueous solution of the polymer (A) and the aqueous solution of the polymer (CA) was measured at a liquid temperature of 23 ° C. using a pH meter (manufactured by DKK-TOA CORPORATION).
［重量平均分子量の測定］
　重合体（Ａ）及び重合体（ＣＡ）の重量平均分子量を、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いて以下の条件で測定した。 [Measurement of weight average molecular weight]
The weight average molecular weights of the polymer (A) and the polymer (CA) were measured using gel permeation chromatography (GPC) under the following conditions.
　ＧＰＣ装置：ＧＰＣ‐１０１（昭和電工（株）製）
　溶媒：０．１Ｍ　ＮａＮＯ３水溶液
　サンプルカラム：Ｓｈｏｄｅｘ　Ｃｏｌｕｍｎ　Ｏｈｐａｋ　ＳＢ－８０６　ＨＱ（８．０ｍｍＩ．Ｄ．　ｘ　３００ｍｍ）　×２
　リファレンスカラム：Ｓｈｏｄｅｘ　Ｃｏｌｕｍｎ　Ｏｈｐａｋ　ＳＢ－８００　ＲＬ（８．０ｍｍＩ．Ｄ．　ｘ　３００ｍｍ）　×２
　カラム温度：４０℃
　試料濃度：０．１質量％
　検出器：ＲＩ－７１Ｓ（株式会社島津製作所製）
　ポンプ：ＤＵ－Ｈ２０００（株式会社島津製作所製）
　圧力：１．３ＭＰａ
　流量：１ｍｌ／ｍｉｎ
　分子量スタンダード：プルラン（Ｐ‐５、Ｐ－１０、Ｐ‐２０、Ｐ－５０、Ｐ‐１００、Ｐ－２００、Ｐ－４００、Ｐ－８００、Ｐ－１３００、Ｐ－２５００（昭和電工（株）製）） GPC device: GPC-101 (manufactured by Showa Denko KK)
Solvent: 0.1M NaNO 3 aqueous solution Sample column: Shodex Volume Ohpak SB-806 HQ (8.0 mm ID x 300 mm) x 2
Reference column: Shodex Colon Ohpak SB-800 RL (8.0 mm ID x 300 mm) x 2
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Detector: RI-71S (manufactured by Shimadzu Corporation)
Pump: DU-H2000 (manufactured by Shimadzu Corporation)
Pressure: 1.3MPa
Flow rate: 1 ml / min
Molecular weight standard: Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (Showa Denko KK) Made))
［重合体の構造］
　生成した重合体の共重合比、すなわち重合体におけるアクリルアミドに由来する構造単位と２－ヒドロキシエチルアクリレートに由来する構造単位との質量比を表１に示す。ここで示す共重合比は、工程２で用いたアクリルアミド、及び２－ヒドロキシエチルアクリレートの質量比である。 [Polymer structure]
Table 1 shows the copolymerization ratio of the produced polymer, that is, the mass ratio of the structural unit derived from acrylamide and the structural unit derived from 2-hydroxyethyl acrylate in the polymer. The copolymerization ratio shown here is the mass ratio of acrylamide and 2-hydroxyethyl acrylate used in step 2.
＜２．重合体（Ｂ）の水溶液の調製＞
　表２に示すポリビニルアルコールである重合体（Ｂ－１）～（Ｂ－４）それぞれについて、重合体１００．０ｇ、及びイオン交換水９００．０ｇを攪拌装置、温度計及びコンデンサーを備えた反応容器中に投入し、窒素雰囲気下で撹拌しながら８０℃まで昇温した。８０℃で３時間撹拌を行い、重合体を溶解した。ここで用いたポリビニルアルコールはいずれもクラレ株式会社製であり、製品グレードは表２に示した通りである。以下の説明において、「重合体（Ｂ－１）、重合体（Ｂ－２）、重合体（Ｂ－３）、または重合体（Ｂ－４）」を「重合体（Ｂ）」とすることもある。 <2. Preparation of aqueous solution of polymer (B)>
For each of the polymers (B-1) to (B-4) which are polyvinyl alcohols shown in Table 2, 100.0 g of the polymer and 900.0 g of ion-exchanged water are mixed in a reaction vessel equipped with a stirrer, a thermometer and a condenser. The temperature was raised to 80 ° C. while stirring under a nitrogen atmosphere. The polymer was dissolved by stirring at 80 ° C. for 3 hours. All of the polyvinyl alcohols used here are manufactured by Kuraray Co., Ltd., and the product grades are as shown in Table 2. In the following description, "polymer (B-1), polymer (B-2), polymer (B-3), or polymer (B-4)" shall be referred to as "polymer (B)". There is also.
　重合体（Ｂ－１）～（Ｂ－４）のけん化度を、ＪＩＳ　Ｋ６７２６（１９９４）３．５項の測定方法（簡便法は用いない）によって測定した。重合体（Ｂ－１）～（Ｂ－４）の重合度を、ＪＩＳ　Ｋ６７２６（１９９４）３．７項の測定方法によって測定した。 The saponification degree of the polymers (B-1) to (B-4) was measured by the measuring method of JIS K6726 (1994) Section 3.5 (the simple method is not used). The degree of polymerization of the polymers (B-1) to (B-4) was measured by the measuring method of JIS K6726 (1994) Section 3.7.
　作製した水溶液の不揮発分（質量％）及び粘度（ｍＰａ・ｓ）を、重合体（Ａ）の水溶液と同様の方法で測定し、測定結果を表２に示した。 The non-volatile content (mass%) and viscosity (mPa · s) of the prepared aqueous solution were measured by the same method as that of the aqueous solution of the polymer (A), and the measurement results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜３．スラリーの作製＞
〔実施例１～８、実施例１０～１２、実施例１４～２１、実施例２２～２５、及び比較例１～５（調製方法Ｉ）〕
（重合体（Ａ）とアルミナとの混合）
　上記工程で作製された重合体（Ａ）の水溶液または重合体（ＣＡ）の水溶液、アルミナ（ＡＬ－４５－１、昭和電工社製平均粒径２μｍ）、及びイオン交換水を自転公転撹拌ミキサーに投入し、２０００ｒｐｍで２分の自公転撹拌による混合を３回行った。 <3. Preparation of slurry>
[Examples 1 to 8, Examples 10 to 12, Examples 14 to 21, Examples 22 to 25, and Comparative Examples 1 to 5 (preparation method I)]
(Mixing of polymer (A) and alumina)
An aqueous solution of the polymer (A) or an aqueous solution of the polymer (CA) produced in the above step, alumina (AL-45-1, average particle size 2 μm manufactured by Showa Denko KK), and ion-exchanged water are used in a rotating and revolving stirring mixer. The mixture was charged and mixed by self-rotating stirring for 2 minutes at 2000 rpm three times.
　ここで、各実施例・比較例で用いた成分及びその量は表３～表５に示す通りである。重合体（Ａ）の水溶液または重合体（ＣＡ）の水溶液の添加量は、重合体（Ａ）または重合体（ＣＡ）の量が表３～表５に示される量になるように調整した。例えば、実施例１では、重合体（Ａ－２）の１４．５質量％水溶液を６５．５ｇ（重合体（Ａ－２）９．５ｇ、水５６．０ｇ）添加した。 Here, the components used in each Example / Comparative Example and their amounts are as shown in Tables 3 to 5. The amount of the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA) was adjusted so that the amount of the polymer (A) or the polymer (CA) was the amount shown in Tables 3 to 5. For example, in Example 1, a 14.5% by mass aqueous solution of the polymer (A-2) was added in an amount of 65.5 g (9.5 g of the polymer (A-2) and 56.0 g of water).
　アルミナの添加量は、表３～表５に示す通りである。例えば、実施例１では、アルミナを１９０ｇ添加した。 The amount of alumina added is as shown in Tables 3 to 5. For example, in Example 1, 190 g of alumina was added.
　この工程では、イオン交換水の添加量は、実施例１～８、１４～２１及び比較例１～４については重合体（Ａ）の水溶液または重合体（ＣＡ）の水溶液に含まれる水と合わせて１００ｇになるように調整した。例えば、実施例１では、イオン交換水を４４．０ｇ添加した。また、実施例１０～１２、２３～２５及び比較例５については、イオン交換水の添加量は、重合体（Ａ）の水溶液または重合体（ＣＡ）の水溶液に含まれる水と合わせて２３３ｇになるように調整した。 In this step, the amount of ion-exchanged water added is combined with the water contained in the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA) for Examples 1 to 8 and 14 to 21 and Comparative Examples 1 to 4. It was adjusted to 100 g. For example, in Example 1, 44.0 g of ion-exchanged water was added. Further, in Examples 10 to 12, 23 to 25 and Comparative Example 5, the amount of ion-exchanged water added was 233 g including the water contained in the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA). Adjusted to be.
（重合体（Ｂ）の添加及び混合）
　次に、上記工程で調製された重合体（Ｂ）の１０．０質量％水溶液及びイオン交換水を、上記工程で希釈された重合体（Ａ）の水溶液または重合体（ＣＡ）の水溶液に加え、５００ｒｐｍで５分の自公転撹拌による混合を２回行い、その後に５００ｒｐｍで１分の公転撹拌による脱泡を行うことにより、スラリーを調製した。 (Addition and mixing of polymer (B))
Next, the 10.0% by mass aqueous solution of the polymer (B) and the ion-exchanged water prepared in the above step are added to the aqueous solution of the polymer (A) or the aqueous solution of the polymer (CA) diluted in the above step. , The slurry was prepared by mixing twice by rotating and stirring for 5 minutes at 500 rpm, and then defoaming by rotating and stirring for 1 minute at 500 rpm.
　ここで、各実施例・比較例で用いた重合体（Ｂ）の水溶液の種類は表３～表５に示す通りであり、重合体（Ｂ）の水溶液の添加量は、重合体（Ｂ）の量が表３～表５に示される量になるように調整した。例えば、実施例１では、重合体（Ｂ－１）の１０．０質量％水溶液を５．０ｇ（重合体（Ｂ－１）０．５０ｇ、水４．５ｇ）添加した。 Here, the types of the aqueous solution of the polymer (B) used in each Example / Comparative Example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (B) added is the polymer (B). The amount of the above was adjusted to be the amount shown in Tables 3 to 5. For example, in Example 1, 5.0 g (0.50 g of polymer (B-1), 4.5 g of water) of a 10.0 mass% aqueous solution of the polymer (B-1) was added.
　この工程で加えたイオン交換水の量は、重合体（Ｂ）の水溶液に含まれる水と合わせて１００ｇになるように調整した。例えば、実施例１では、イオン交換水を９５．５ｇ添加した。 The amount of ion-exchanged water added in this step was adjusted to 100 g together with the water contained in the aqueous solution of the polymer (B). For example, in Example 1, 95.5 g of ion-exchanged water was added.
　以上に述べたスラリーの調製方法を表３～表５において調製方法Ｉとする。 The slurry preparation method described above is referred to as preparation method I in Tables 3 to 5.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
〔実施例９、１３、２２及び２６（調製方法ＩＩ）〕
　上記工程で作製された重合体（Ａ）の水溶液、アルミナ（ＡＬ－４５－１）、上記工程で調製された重合体（Ｂ）の１０．０質量％水溶液、及びイオン交換水を自転公転撹拌ミキサーに投入し、２０００ｒｐｍで２分の自公転撹拌による混合を３回行った。 [Examples 9, 13, 22 and 26 (preparation method II)]
The aqueous solution of the polymer (A) prepared in the above step, alumina (AL-45-1), the 10.0 mass% aqueous solution of the polymer (B) prepared in the above step, and the ion-exchanged water are rotated and revolved and stirred. It was put into a mixer, and the mixture was mixed by rotation rotation stirring for 2 minutes at 2000 rpm three times.
　ここで、各実施例で用いた重合体（Ａ）の水溶液の種類は表３～表５に示す通りであり、重合体（Ａ）の水溶液の添加量は、重合体（Ａ）の量が表３～表５に示される量になるように調整した。例えば、実施例９では、重合体（Ａ－２）の１４．５質量％水溶液を５５．２ｇ（重合体（Ａ－２）８．０ｇ、水４７．２ｇ）添加した。 Here, the types of the aqueous solution of the polymer (A) used in each example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (A) added is the amount of the polymer (A). The amount was adjusted to be as shown in Tables 3 to 5. For example, in Example 9, 55.2 g (8.0 g of the polymer (A-2) and 47.2 g of water) of a 14.5% by mass aqueous solution of the polymer (A-2) was added.
　アルミナの添加量は、実施例９では１９０ｇ、実施例１３では３２３ｇであった。 The amount of alumina added was 190 g in Example 9 and 323 g in Example 13.
　ここで、各実施例で用いた重合体（Ｂ）の水溶液の種類は表３～表５に示す通りであり、重合体（Ｂ）の水溶液の添加量は、重合体（Ｂ）の量が表３～表５に示される量になるように調整した。例えば、実施例９では、重合体（Ｂ－１）の１０．０質量％水溶液を２０．０ｇ（重合体（Ｂ－１）２．０ｇ、水１８．０ｇ）添加した。 Here, the types of the aqueous solution of the polymer (B) used in each example are as shown in Tables 3 to 5, and the amount of the aqueous solution of the polymer (B) added is the amount of the polymer (B). The amount was adjusted to be as shown in Tables 3 to 5. For example, in Example 9, a 10.0 mass% aqueous solution of the polymer (B-1) was added in an amount of 20.0 g (2.0 g of the polymer (B-1) and 18.0 g of water).
　イオン交換水の添加量は、実施例９では３４．８ｇ、実施例１３では１７０．９ｇであった。 The amount of ion-exchanged water added was 34.8 g in Example 9 and 170.9 g in Example 13.
　その後、イオン交換水１００ｇを投入し、５００ｒｐｍで５分の自公転撹拌による混合を２回行い、その後に５００ｒｐｍで１分の公転撹拌による脱泡を行うことにより、スラリーを調製した。 After that, 100 g of ion-exchanged water was added, and mixing was performed twice by rotating and stirring at 500 rpm for 5 minutes, and then defoaming was performed by rotating and stirring at 500 rpm for 1 minute to prepare a slurry.
　以上に述べたスラリーの調製方法を表３～表５において調製方法ＩＩとする。 The slurry preparation method described above is referred to as preparation method II in Tables 3 to 5.
〔比較例６〕
　重合体（Ａ－２）の１４．５質量％水溶液６９．０ｇ（重合体（Ａ－２）１０．０ｇ、水５９．０ｇ）、アルミナ（ＡＬ－４５－１）１９０ｇ、及びイオン交換水４１．０ｇを自転公転撹拌ミキサーに投入し、２０００ｒｐｍで２分の自公転撹拌による混合を３回行った。 [Comparative Example 6]
69.0 g of 14.5 mass% aqueous solution of polymer (A-2) (10.0 g of polymer (A-2), 59.0 g of water), 190 g of alumina (AL-45-1), and ion-exchanged water 41. .0 g was put into a rotation / revolution stirring mixer, and mixing was performed 3 times by rotation / revolution stirring for 2 minutes at 2000 rpm.
　その後、イオン交換水１００ｇを投入し、５００ｒｐｍで５分の自公転撹拌による混合を２回行い、その後に５００ｒｐｍで１分の公転撹拌による脱泡を行うことにより、スラリーを調製した。 After that, 100 g of ion-exchanged water was added, and mixing was performed twice by rotating and stirring at 500 rpm for 5 minutes, and then defoaming was performed by rotating and stirring at 500 rpm for 1 minute to prepare a slurry.
〔比較例７〕
　重合体（ＣＡ－１）の１４．５質量％水溶液を同量用いたこと以外は比較例６と同様にスラリーを調製した。 [Comparative Example 7]
A slurry was prepared in the same manner as in Comparative Example 6 except that the same amount of a 14.5% by mass aqueous solution of the polymer (CA-1) was used.
〔比較例８〕
　重合体（ＣＡ－３）の３．０質量％水溶液３３３ｇ（重合体（ＣＡ－３）１０．０ｇ、水３２３ｇ）、及びアルミナ（ＡＬ－４５－１）３２３ｇを自転公転撹拌ミキサーに投入し、２０００ｒｐｍで２分の自公転撹拌による混合を３回行った。 [Comparative Example 8]
333 g of a 3.0 mass% aqueous solution of the polymer (CA-3) (10.0 g of the polymer (CA-3), 323 g of water) and 323 g of alumina (AL-45-1) were put into a rotating revolution stirring mixer. Mixing was carried out 3 times by self-revolving stirring for 2 minutes at 2000 rpm.
　その後、イオン交換水１０ｇを投入し、５００ｒｐｍで５分の自公転撹拌による混合を２回行い、その後に５００ｒｐｍで１分の公転撹拌による脱泡を行うことにより、スラリーを調製した。 After that, 10 g of ion-exchanged water was added, and mixing was performed twice by rotating and stirring at 500 rpm for 5 minutes, and then defoaming was performed by rotating and stirring at 500 rpm for 1 minute to prepare a slurry.
〔比較例９〕
　重合体（Ｂ－３）の１０．０質量％水溶液１００ｇ（重合体（Ｂ－３）１０．０ｇ、水９０．０ｇ）、アルミナ（ＡＬ－４５－１）１９０ｇ、及びイオン交換水１０ｇを自転公転撹拌ミキサーに投入し、２０００ｒｐｍで２分の自公転撹拌による混合を３回行った。 [Comparative Example 9]
Rotating 100 g of a 10.0 mass% aqueous solution of the polymer (B-3) (10.0 g of the polymer (B-3), 90.0 g of water), 190 g of alumina (AL-45-1), and 10 g of ion-exchanged water. The mixture was put into a revolution stirring mixer and mixed by rotation rotation stirring for 2 minutes at 2000 rpm three times.
　その後、イオン交換水１００ｇを投入し、５００ｒｐｍで５分の自公転撹拌による混合を２回行い、その後に５００ｒｐｍで１分の公転撹拌による脱泡を行うことにより、スラリーを調製した。 After that, 100 g of ion-exchanged water was added, and mixing was performed twice by rotating and stirring at 500 rpm for 5 minutes, and then defoaming was performed by rotating and stirring at 500 rpm for 1 minute to prepare a slurry.
〔比較例１０〕
　重合体（Ｂ－３）の１０．０質量％水溶液の代わりに、重合体（Ｂ－４）の１０．０質量％水溶液を同量用いたこと以外は比較例９と同様にスラリーを調製した。 [Comparative Example 10]
A slurry was prepared in the same manner as in Comparative Example 9 except that the same amount of a 10.0% by mass aqueous solution of the polymer (B-4) was used instead of the 10.0% by mass aqueous solution of the polymer (B-3). ..
〔比較例１１〕
　比較例１１においては、スラリーを調製せず、後述するセパレータのみで評価を行った。 [Comparative Example 11]
In Comparative Example 11, the slurry was not prepared, and the evaluation was performed using only the separator described later.
＜４．セパレータの評価＞
〔４－１．コーティング層の形成（セパレータの作製）〕
　比較例１１以外の各実施例及び比較例において作製したスラリーを、２５μｍのポリプロピレン多孔膜（積水化学工業社製：ＥＳＦＩＮＯ　Ｐ）の基材の両面に塗工した。塗工は、直径１０ｍｍのＮｏ．８のバーコーターを用いて行った。その後、スラリーが塗工された基材を６０℃で５分間乾燥し、基材上にコーティング層が形成されたセパレータを得た。基材上に形成されたコーティング層の厚さは、いずれの実施例及び比較例（比較例１１除く）も、両面とも３．５μｍであった。 <4. Separator evaluation>
[4-1. Formation of coating layer (preparation of separator)]
The slurries prepared in each Example and Comparative Example other than Comparative Example 11 were coated on both surfaces of a 25 μm polypropylene porous membrane (manufactured by Sekisui Chemical Co., Ltd .: ESFINO P). The coating is No. 10 mm in diameter. This was done using 8 bar coaters. Then, the substrate coated with the slurry was dried at 60 ° C. for 5 minutes to obtain a separator having a coating layer formed on the substrate. The thickness of the coating layer formed on the substrate was 3.5 μm on both sides in both Examples and Comparative Examples (excluding Comparative Example 11).
　比較例１１では、セパレータへのスラリーの塗工は行わず、後述する熱収縮のみ評価した。 In Comparative Example 11, the slurry was not applied to the separator, and only the heat shrinkage described later was evaluated.
〔４－２．基材に対するスラリーの濡れ性〕
　基材へスラリーを塗工した直後の状態について観察し、基材に対するスラリーの濡れ性について以下のように評価した。
　Ａ：ハジキ無し
　Ｂ：塗工面の端部においてハジキが見られた。
　Ｃ：塗工全面においてハジキが生じた。 [4-2. Wetting property of slurry to the substrate]
The state immediately after the slurry was applied to the substrate was observed, and the wettability of the slurry with respect to the substrate was evaluated as follows.
A: No repellent B: Repellent was seen at the edge of the coated surface.
C: Repellent occurred on the entire surface of the coating.
〔４－３．基材に対するスラリーの塗工性〕
　基材へスラリーを塗工した直後の状態について観察し、基材に対するスラリーの塗工性について以下のように評価した。
　Ａ：塗工の作業性が良好で、塗工によるスジは見られなかった。
　Ｂ：粘度が高く、塗工によるスジが見られた。
　Ｃ：粘度が非常に高く、塗工面に顕著なスジが見られた。または塗工不能であった。 [4-3. Slurry coatability on substrate]
The state immediately after the slurry was applied to the substrate was observed, and the coatability of the slurry on the substrate was evaluated as follows.
A: The workability of the coating was good, and no streaks due to the coating were observed.
B: The viscosity was high, and streaks due to coating were observed.
C: The viscosity was very high, and remarkable streaks were observed on the coated surface. Or it was impossible to paint.
〔４－４．コーティング層の剥離強度〕
　コーティング層の基材に対する剥離強度を以下のように測定した。上記工程により作製された両面にコーティング層を有するセパレータを１５ｍｍ×１００ｍｍのサイズにカットし、試験片とした。 [4-4. Peeling strength of coating layer]
The peel strength of the coating layer with respect to the substrate was measured as follows. A separator having coating layers on both sides produced by the above step was cut into a size of 15 mm × 100 mm to obtain a test piece.
　試験片と、幅５０ｍｍ、長さ２００ｍｍＳＵＳ板とを両面テープ（ＮＩＴＴＯＴＡＰＥ（登録商標）　Ｎｏ．５、日東電工（株）製）を用いて、試験片の中心とＳＵＳ板の中心とが一致するように貼り合わせた。貼り合わせは、２３℃の雰囲気下で２ｋｇローラーを１往復させることにより行った。なお、両面テープは試験片の全範囲をカバーするように貼り合わせた。ＳＵＳ板に固定された試験片のコーティング層に幅１０ｍｍのセロハンテープ（コクヨ　セロハンテープ　Ｔ－ＳＥ１５Ｎ）を貼り付けた。貼り付けは、２３℃の雰囲気下で２ｋｇローラーを１往復させることにより行った。コーティング層にセロハンテープを貼り付けた状態で２０分放置した後、セロハンテープの一端を１８０°折り返し、この一端と対向する他端に向かって速度１００ｍｍ／分で引っ張って剥がし、剥離長さ（ｍｍ）－剥離力（ｍＮ）のグラフを得た。試験機（テンシロンＲＴＧ－１２１０（株式会社エー・アンド・デイ製））を用いた。得られたグラフにおいて剥離長さ１０～４５ｍｍにおける剥離力の平均値（ｍＮ）を算出し、剥離力の平均値を試験片の幅１５ｍｍで割った数値をコーティング層の剥離強度（ｍＮ／ｍｍ）とした。なお、いずれの実施例及び比較例（比較例１１除く）においても、試験中、両面テープとＳＵＳ板との間での剥離、両面テープと試験片との間での剥離、及びセロハンテープとコーティング層との間での層間剥離は起こらなかった。 Use double-sided tape (NITTO TAPE (registered trademark) No. 5, manufactured by Nitto Denko KK) to align the center of the test piece with the center of the SUS plate so that the test piece and the SUS plate with a width of 50 mm and a length of 200 mm are aligned with each other. I pasted it on. The bonding was performed by reciprocating a 2 kg roller once in an atmosphere of 23 ° C. The double-sided tape was attached so as to cover the entire range of the test piece. A cellophane tape (KOKUYO cellophane tape T-SE15N) with a width of 10 mm was attached to the coating layer of the test piece fixed to the SUS plate. The pasting was performed by reciprocating a 2 kg roller once in an atmosphere of 23 ° C. After leaving the cellophane tape attached to the coating layer for 20 minutes, one end of the cellophane tape is folded back 180 ° and pulled toward the other end facing the other end at a speed of 100 mm / min to peel it off, and the peeling length (mm). ) -A graph of peeling force (mN) was obtained. A testing machine (Tensilon RTG-1210 (manufactured by A & D Co., Ltd.)) was used. In the obtained graph, the average value (mN) of the peeling force at the peeling length of 10 to 45 mm was calculated, and the value obtained by dividing the average value of the peeling force by the width of the test piece of 15 mm was the peeling strength (mN / mm) of the coating layer. And said. In each of the Examples and Comparative Examples (excluding Comparative Example 11), during the test, peeling between the double-sided tape and the SUS plate, peeling between the double-sided tape and the test piece, and cellophane tape and coating. No delamination with the layers occurred.
〔４－５．熱収縮〕
　セパレータをＭＤ方向（ｍａｃｈｉｎｅ　ｄｉｒｒｅｃｔｉｏｎ）×ＴＤ方向（ｔｒａｎｓｖｅｒｓｅ　ｄｉｒｒｅｃｔｉｏｎ）＝１００ｍｍ×６０ｍｍの長方形に切り出した。セパレータを厚さ０．８ｍｍ×長さ１５０ｍｍ×幅７０ｍｍ、質量６５ｇのステンレス板に乗せ、さらにセパレータの上から同じサイズ及び質量のステンレス板を乗せた。すなわち、セパレータは２枚のステンレス板の間に挟まれ、セパレータは、上側のステンレス板の重さによって固定される。ステンレス板に挟まれたセパレータを１５０℃の恒温槽中に６０分静置した。セパレータを取り出した後、ＭＤ方向の長さをノギスで読み取り、次式にしたがって熱収縮率を算出した。 [4-5. Heat shrinkage]
The separator was cut into a rectangle of MD direction (machine direction) × TD direction (transverse direction) = 100 mm × 60 mm. The separator was placed on a stainless steel plate having a thickness of 0.8 mm, a length of 150 mm, a width of 70 mm, and a mass of 65 g, and a stainless steel plate of the same size and mass was placed on the separator. That is, the separator is sandwiched between two stainless steel plates, and the separator is fixed by the weight of the upper stainless steel plate. The separator sandwiched between the stainless steel plates was allowed to stand in a constant temperature bath at 150 ° C. for 60 minutes. After taking out the separator, the length in the MD direction was read with a caliper, and the heat shrinkage rate was calculated according to the following equation.
　熱収縮率（％）＝［｛（１００（ｍｍ）－加熱後の長さ（ｍｍ））／１００（ｍｍ）｝×１００］ Heat shrinkage rate (%) = [{(100 (mm) -length after heating (mm)) / 100 (mm)} x 100]
＜５．評価結果＞
　表３～表５からわかるように、いずれの実施例においても、基材に対するスラリーの濡れ性及び塗工性ともに良好であった。また、基材上に形成されたコーティング層は、剥離強度が高く、セパレータの熱収縮が小さかった。 <5. Evaluation result>
As can be seen from Tables 3 to 5, in each of the examples, both the wettability and the coatability of the slurry with respect to the substrate were good. Further, the coating layer formed on the substrate had high peel strength and the heat shrinkage of the separator was small.
　比較例１では、重合体（Ａ）の代わりにアクリルアミドに由来する構造単位（第１構造単位（ａ１））を多く含む重合体（ＣＡ－１）を用いてスラリーを作製した。しかし、作製されたスラリーは、基材に塗工できず、コーティング層が形成されなかった。 In Comparative Example 1, a slurry was prepared using a polymer (CA-1) containing a large amount of structural units (first structural unit (a1)) derived from acrylamide instead of the polymer (A). However, the produced slurry could not be applied to the base material, and a coating layer was not formed.
　比較例２及び比較例３では、バインダーに含まれるポリビニルアルコール（重合体（Ｂ））の量を多くしたが、セパレータの熱収縮を十分に抑制できなかった。 In Comparative Example 2 and Comparative Example 3, although the amount of polyvinyl alcohol (polymer (B)) contained in the binder was increased, the thermal shrinkage of the separator could not be sufficiently suppressed.
　比較例４では、重合体（Ａ）の代わりに２－ヒドロキシエチルアクリレートに由来する構造単位（第２構造単位（ａ２））を多く含む重合体（ＣＡ－２）を用いたが、セパレータの熱収縮を十分に抑制できなかった。 In Comparative Example 4, a polymer (CA-2) containing a large amount of structural units (second structural unit (a2)) derived from 2-hydroxyethyl acrylate was used instead of the polymer (A), but the heat of the separator was used. The contraction could not be sufficiently suppressed.
　比較例５では、重合体（Ａ）の代わりにカルボキシメチルセルロースナトリウム塩（重合体（ＣＡ－３））を用いてスラリーを作製した。しかし、作製されたスラリーを基材に塗布したら、塗膜に顕著なスジ発生した。また、形成されたコーティング層はセパレータの熱収縮を十分に抑制できなかった。 In Comparative Example 5, a slurry was prepared using a sodium carboxymethyl cellulose salt (polymer (CA-3)) instead of the polymer (A). However, when the prepared slurry was applied to the substrate, remarkable streaks were generated on the coating film. In addition, the formed coating layer could not sufficiently suppress the heat shrinkage of the separator.
　比較例６では、重合体（Ｂ）を含まないバインダーを用いたが、形成されたコーティング層の剥離強度が十分ではなかった。 In Comparative Example 6, a binder containing no polymer (B) was used, but the peel strength of the formed coating layer was not sufficient.
　比較例７では、重合体（Ａ）の代わりにアクリルアミドに由来する構造単位（第１構造単位（ａ１））を多く含む重合体（ＣＡ－１）を用い、さらに重合体（Ｂ）を含まないスラリーを作製した。しかし、作製されたスラリーは基材に対する濡れ性が不十分で、スラリーを基材に塗工できず、コーティング層が形成できなかった。 In Comparative Example 7, a polymer (CA-1) containing a large amount of structural units derived from acrylamide (first structural unit (a1)) is used instead of the polymer (A), and the polymer (B) is not contained. A slurry was prepared. However, the produced slurry had insufficient wettability to the base material, the slurry could not be applied to the base material, and the coating layer could not be formed.
　比較例８では、重合体（Ａ）の代わりにカルボキシメチルセルロースナトリウム塩（重合体（ＣＡ－３））を用い、さらに重合体（Ｂ）を含まないスラリーを作製した。しかし、作製されたスラリーを基材に塗布したら、塗膜に顕著なスジが発生した。また、形成されたコーティング層の剥離強度は不十分であった。さらに、形成されたコーティング層はセパレータの熱収縮を十分に抑制できなかった。 In Comparative Example 8, a sodium carboxymethyl cellulose salt (polymer (CA-3)) was used instead of the polymer (A) to prepare a slurry containing no polymer (B). However, when the prepared slurry was applied to the substrate, remarkable streaks were generated on the coating film. In addition, the peel strength of the formed coating layer was insufficient. Further, the formed coating layer could not sufficiently suppress the heat shrinkage of the separator.
　比較例９及び比較例１０では、重合体（Ａ）を含まないバインダーを用いたが、形成されたコーティング層はセパレータの熱収縮を十分に抑制できなかった。 In Comparative Example 9 and Comparative Example 10, a binder containing no polymer (A) was used, but the formed coating layer could not sufficiently suppress the thermal shrinkage of the separator.
　比較例１１では、コーティング層を形成させず、基材のみのセパレータで評価を行ったが、セパレータの熱収縮が大きかった。 In Comparative Example 11, the evaluation was performed using a separator containing only the base material without forming the coating layer, but the heat shrinkage of the separator was large.
　以上のことから、本発明によれば、基材への濡れ性及び塗工性が良好なスラリーの作製が可能で、剥離強度の高いコーティング層をセパレータに形成させることができ、かつセパレータの熱収縮を抑制できる非水系二次電池用セパレータバインダー及び非水系二次電池用セパレータバインダー組成物を提供することができると言える。また、本発明によれば、基材に対する剥離強度が高いコーティング層を備え、熱収縮の小さい非水系二次電池用セパレータを提供することができると言える。 From the above, according to the present invention, it is possible to produce a slurry having good wettability to a substrate and good coatability, a coating layer having high peel strength can be formed on the separator, and the heat of the separator can be formed. It can be said that it is possible to provide a separator binder for a non-aqueous secondary battery and a separator binder composition for a non-aqueous secondary battery capable of suppressing shrinkage. Further, according to the present invention, it can be said that it is possible to provide a separator for a non-aqueous secondary battery which is provided with a coating layer having a high peel strength against a substrate and has a small heat shrinkage.

Claims (17)

  1. 　重合体（Ａ）及び重合体（Ｂ）を含む非水系二次電池用セパレータバインダーであって、
    　前記重合体（Ａ）は、エチレン性不飽和結合を有する化合物の重合体であり、（メタ）アクリルアミドに由来する第１構造単位（ａ１）と、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）と有し、
    　前記重合体（Ｂ）は、けん化度５５ｍｏｌ％以上のポリビニルアルコールであり、
    　前記重合体（Ａ）における、前記第１構造単位（ａ１）の含有量と前記第２構造単位（ａ２）の含有量との質量比の値は、５５．０／４５．０以上９５．０／５．０以下であり、　前記重合体（Ａ）の含有量と前記重合体（Ｂ）の含有量との質量比の値は、５５．０／４５．０以上９７．０／３．０以下である非水系二次電池用セパレータバインダー。     A separator binder for a non-aqueous secondary battery containing the polymer (A) and the polymer (B).
    The polymer (A) is a polymer of a compound having an ethylenically unsaturated bond, and is derived from a first structural unit (a1) derived from (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond. Has a second structural unit (a2) to be
    The polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
    The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. It is /5.0 or less, and the value of the mass ratio of the content of the polymer (A) to the content of the polymer (B) is 55.0 / 45.0 or more and 97.0 / 3.0. The following separator binder for non-aqueous secondary batteries.
  2. 　前記重合体（Ａ）及び前記重合体（Ｂ）のみからなる、請求項１に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to claim 1, which comprises only the polymer (A) and the polymer (B).
  3. 　前記重合体（Ａ）は、アニオン性官能基を有さない請求項１または２に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to claim 1 or 2, wherein the polymer (A) does not have an anionic functional group.
  4. 　前記重合体（Ｂ）は、けん化度６５ｍｏｌ％以上である請求項１～３のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the polymer (B) has a saponification degree of 65 mol% or more.
  5. 　前記重合体（Ｂ）は、重合度１００以上５０００以下である請求項１～４のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein the polymer (B) has a degree of polymerization of 100 or more and 5000 or less.
  6. 　前記重合体（Ａ）における、前記第１構造単位（ａ１）及び前記第２構造単位（ａ２）の合計含有率は８０質量％以上である請求項１～５のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The non-according to any one of claims 1 to 5, wherein the total content of the first structural unit (a1) and the second structural unit (a2) in the polymer (A) is 80% by mass or more. Separator binder for water-based secondary batteries.
  7. 　前記重合体（Ａ）は、前記第１構造単位（ａ１）及び前記第２構造単位（ａ２）のみからなる、請求項１～６のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 6, wherein the polymer (A) comprises only the first structural unit (a1) and the second structural unit (a2). ..
  8. 　前記第２構造単位（ａ２）は、水酸基を有する（メタ）アクリレートに由来する構造単位である請求項１～７のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 7, wherein the second structural unit (a2) is a structural unit derived from a (meth) acrylate having a hydroxyl group.
  9. 　前記第２構造単位（ａ２）は、２－ヒドロキシエチル（メタ）アクリレートに由来する構造単位である、請求項１～７のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 7, wherein the second structural unit (a2) is a structural unit derived from 2-hydroxyethyl (meth) acrylate.
  10. 　前記第２構造単位（ａ２）は、２－ヒドロキシエチルメタクリレートに由来する構造単位である、請求項１～７のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 7, wherein the second structural unit (a2) is a structural unit derived from 2-hydroxyethyl methacrylate.
  11. 　前記重合体（Ａ）の水１００ｇへの溶解度は、２．０ｇ／１００ｇ以上である請求項１～１０のいずれか一項に記載の非水系二次電池用セパレータバインダー。 The separator binder for a non-aqueous secondary battery according to any one of claims 1 to 10, wherein the solubility of the polymer (A) in 100 g of water is 2.0 g / 100 g or more.
  12. 　請求項１～１１のいずれか一項に記載の非水系二次電池用セパレータバインダーと、水性媒体とを含む非水系二次電池用セパレータバインダー組成物。 A separator binder composition for a non-aqueous secondary battery, which comprises the separator binder for a non-aqueous secondary battery according to any one of claims 1 to 11 and an aqueous medium.
  13. 　請求項１～１１のいずれか一項に記載の非水系二次電池用セパレータバインダーと、フィラーと、水性媒体とを含む、非水系二次電池用セパレータスラリー。 A separator slurry for a non-aqueous secondary battery, which comprises the separator binder for a non-aqueous secondary battery according to any one of claims 1 to 11, a filler, and an aqueous medium.
  14. 　多孔質フィルムである基材と、該基材の表面に形成されたコーティング層とを備えた非水系二次電池用セパレータであって、
    　前記コーティング層は、請求項１～１１のいずれか一項に記載の非水系二次電池用セパレータバインダーと、フィラーとを含む非水系二次電池用セパレータ。     A separator for a non-aqueous secondary battery including a substrate which is a porous film and a coating layer formed on the surface of the substrate.
    The coating layer is a separator for a non-aqueous secondary battery containing the separator binder for a non-aqueous secondary battery according to any one of claims 1 to 11 and a filler.
  15. 　前記コーティング層における、前記非水系二次電池用セパレータバインダーの含有量と前記フィラーの含有量との質量比の値は、１．０／９９．０以上１５．０／８５．０以下である請求項１４に記載の非水系二次電池用セパレータ。 The value of the mass ratio of the content of the separator binder for a non-aqueous secondary battery and the content of the filler in the coating layer is 1.0 / 99.0 or more and 15.0 / 85.0 or less. Item 14. The separator for a non-aqueous secondary battery according to Item 14.
  16. 　非水系二次電池用セパレータスラリーの製造方法であって、
    　重合体（Ａ）、及びフィラーを水性媒体中で混合する第１工程と、
    　重合体（Ｂ）を、前記第１工程で得られた混合物に加えて混合する第２工程と、を含み、
    　前記重合体（Ａ）は、エチレン性不飽和結合を有する化合物の重合体であり、（メタ）アクリルアミドに由来する第１構造単位（ａ１）と、水酸基及びエチレン性不飽和結合を有する化合物に由来する第２構造単位（ａ２）と有し、
    　前記重合体（Ｂ）は、けん化度５５ｍｏｌ％以上のポリビニルアルコールであり、
    　前記重合体（Ａ）における、前記第１構造単位（ａ１）の含有量と前記第２構造単位（ａ２）の含有量との質量比の値は、５５．０／４５．０以上９５．０／５．０以下であり、
    　前記重合体（Ａ）の使用量と前記重合体（Ｂ）の使用量との質量比の値は、５５．０／４５．０以上９７．０／３．０以下である非水系二次電池用セパレータスラリーの製造方法。     A method for manufacturing a separator slurry for a non-aqueous secondary battery.
    The first step of mixing the polymer (A) and the filler in an aqueous medium, and
    A second step of adding and mixing the polymer (B) to the mixture obtained in the first step is included.
    The polymer (A) is a polymer of a compound having an ethylenically unsaturated bond, and is derived from a first structural unit (a1) derived from (meth) acrylamide and a compound having a hydroxyl group and an ethylenically unsaturated bond. Has a second structural unit (a2) to be
    The polymer (B) is polyvinyl alcohol having a saponification degree of 55 mol% or more.
    The value of the mass ratio of the content of the first structural unit (a1) to the content of the second structural unit (a2) in the polymer (A) is 55.0 / 45.0 or more and 95.0. /5.0 or less,
    The value of the mass ratio between the amount of the polymer (A) used and the amount of the polymer (B) used is 55.0 / 45.0 or more and 97.0 / 3.0 or less, which is a non-aqueous secondary battery. Method for manufacturing separator slurry.
  17. 　請求項１４又は１５に記載の非水系二次電池用セパレータを含む、非水系二次電池。 A non-aqueous secondary battery comprising the separator for a non-aqueous secondary battery according to claim 14 or 15.
PCT/JP2021/046014 2020-12-24 2021-12-14 Separator binder for nonaqueous secondary battery, separator for nonaqueous secondary battery, method for producing separator slurry for nonaqueous secondary battery, and nonaqueous secondary battery WO2022138322A1 (en)

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