Classifications

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  • C08F2/00—Processes of polymerisation
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  • C08F212/00—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 aromatic carbocyclic ring
  • C08F212/02—Monomers containing only one unsaturated aliphatic radical
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  • C08F257/00—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00
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  • C09J133/00—Adhesives based on 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 only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
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  • C09J133/00—Adhesives based on 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 only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/18—Homopolymers or copolymers of nitriles
  • C09J133/20—Homopolymers or copolymers of acrylonitrile
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
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  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
• • H—ELECTRICITY
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  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/48—Conductive polymers
• • H—ELECTRICITY
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  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/52—Separators
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
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  • 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
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
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  • 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
  • H01M50/417—Polyolefins
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  • 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
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/443—Particulate material
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• • 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
  • C08F2800/00—Copolymer characterised by the proportions of the comonomers expressed
  • C08F2800/20—Copolymer characterised by the proportions of the comonomers expressed as weight or mass percentages
• • 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
  • C08F2810/00—Chemical modification of a polymer
  • C08F2810/20—Chemical modification of a polymer leading to a crosslinking, either explicitly or inherently
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a composition for an electrochemical device functional layer, a laminate for an electrochemical device, and an electrochemical device.
• Electrochemical devices such as lithium ion secondary batteries and electric double layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, so they are used in a wide range of applications.
• a lithium ion secondary battery generally includes a positive electrode, a negative electrode, and battery members such as a separator that isolates the positive and negative electrodes and prevents short circuits between the positive and negative electrodes.
• constituent members are used that are provided with a functional layer such as an adhesive layer for the purpose of improving adhesiveness between constituent members.
• a functional layer such as an adhesive layer for the purpose of improving adhesiveness between constituent members.
• an electrode formed by forming an electrode mixture layer on a current collector and further forming a functional layer on an electrode base material, and a separator formed by forming a functional layer on a separator base material are battery members. is used as.
• further improvements in functional layers have been studied with the aim of further improving the performance of electrochemical devices such as lithium ion secondary batteries.
• Patent Document 1 a particulate polymer having an average circularity of 0.90 or more and less than 0.99 and a volume average particle diameter of 1.0 ⁇ m or more and 10.0 ⁇ m or less is electrochemically It has been proposed to form a functional layer that can exhibit excellent adhesiveness by incorporating it into a composition for a device functional layer.
• the functional layer formed using the above-mentioned conventionally known particulate polymers, etc. has the potential to further improve its adhesion after immersion in an electrolytic solution (hereinafter also referred to as "wet adhesion"). There was room.
• an object of the present invention is to provide a composition for an electrochemical device functional layer that can form a functional layer with excellent wet adhesion. Further, the present invention aims to provide a laminate for an electrochemical device including a functional layer using the composition for an electrochemical device functional layer, and an electrochemical device including this laminate for an electrochemical device. do.
• the present inventor conducted extensive studies in order to achieve the above object.
• the present inventor has developed a composition for an electrochemical device functional layer that includes a particulate polymer having a predetermined volume particle diameter D50 and a predetermined particle size distribution (hereinafter sometimes referred to as "particle size distribution ⁇ ").
• particle size distribution ⁇ a predetermined particle size distribution
• the present invention aims to advantageously solve the above-mentioned problems, and the present invention provides a composition for an electrochemical element functional layer containing a particulate polymer, the composition comprising a particulate polymer. has a volume particle diameter D50 of 1.0 ⁇ m or more and 10.0 ⁇ m or less, and the proportion of particles in which the particulate polymer has a particle diameter 1.5 times or more the volume particle diameter D50 is
• the composition for an electrochemical device functional layer has a particle size distribution ⁇ of 0.5% by volume or more and 5.0% by volume or less, based on 100% by volume of the polymer. With such a composition for an electrochemical device functional layer, a functional layer with excellent wet adhesion can be formed.
• volume particle diameter D50 of a particulate polymer is defined as a particle whose cumulative volume calculated from the small diameter side is 50% in the particle size distribution (volume basis) measured using a particle size distribution measuring device. It means the diameter and can be measured according to the method described in Examples.
• the particulate polymer has an average circularity of 0.95 or more and 0.99 or less, and the particulate polymer has a circularity of less than 0.95. It is preferable that the circularity distribution has a circularity distribution in which the proportion of particles having the above particle-like polymer is less than 10% on a number basis with respect to the particulate polymer. If the average circularity of the particulate polymer is equal to or higher than the lower limit above, the bonding point between the particulate polymer and a material other than the particulate polymer in the functional layer formed using the electrochemical element functional layer composition.
• dry adhesion the adhesion before immersion in the electrolytic solution
• dry adhesion the adhesion before immersion in the electrolytic solution
• the average circularity of the particulate polymer is below the above upper limit, the state of the particulate polymer will be stabilized in the functional layer, suppressing powder falling off, and improving wet adhesion and dry adhesion. can.
• the proportion of particles having a circularity of less than 0.95 in the particulate polymer is less than the above upper limit, there will be many bonding points between the particulate polymer and a material other than the particulate polymer in the functional layer, Powder falling is suppressed, and as a result, wet adhesion and dry adhesion can be improved.
• the average circularity and circularity distribution of a particulate polymer can be measured by the method described in the Examples of this specification.
• the amount of the particulate polymer eluted into tetrahydrofuran is preferably 5% by mass or more and 50% by mass or less. If the amount of the particulate polymer eluted into tetrahydrofuran is equal to or higher than the above lower limit, the particulate polymer will not be present at the contact surface with the electrochemical element member that is in contact with the functional layer formed using the composition for an electrochemical element functional layer. It deforms appropriately, and as a result, wet adhesion and dry adhesion can be improved.
• the amount of elution of the particulate polymer into tetrahydrofuran is below the above upper limit, excessive deformation of the particulate polymer is suppressed, and as a result, for example, when a laminate or an electrochemical element including a functional layer is rolled up, It is possible to suppress adhesion (so-called blocking) between the functional layer and the electrochemical element member during storage and transportation in that state. That is, the blocking resistance of the functional layer can be improved. Furthermore, in the electrochemical device, the amount of components of the particulate polymer that may cause an increase in resistance value eluted into the electrolytic solution can be reduced, and as a result, the cycle characteristics of the electrochemical device can be improved. In this specification, "the amount of elution into tetrahydrofuran" of a particulate polymer can be measured using the method described in the Examples of this specification.
• the particulate polymer includes an aromatic monovinyl monomer unit, an aromatic divinyl monomer unit, a di(meth)acrylate monomer unit, and a di(meth)acrylate monomer unit.
• the content of the crosslinkable monomer unit is preferably 0.1% by mass or more and 5% by mass or less, when the total repeating units in the polymer are 100% by mass.
• the particulate polymer is made of particles containing a polymer containing an aromatic monovinyl monomer unit, wet adhesion and dry adhesion can be improved. If the particulate polymer is made of particles containing a polymer containing the above-mentioned crosslinkable monomer unit, wet adhesion can be improved. Moreover, excessive deformation of the particulate polymer is suppressed, and as a result, the blocking resistance of the functional layer can be improved. Furthermore, in the electrochemical device, the amount of components of the particulate polymer that may cause an increase in resistance value eluted into the electrolyte solution can be reduced, and as a result, the cycle characteristics of the electrochemical device can be improved.
• the content of the crosslinkable monomer unit is at least the above lower limit, the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device can be improved.
• the content of the crosslinkable monomer unit is below the above upper limit, the particulate polymer will be appropriately deformed, and as a result, wet adhesion and dry adhesion can be improved.
• the expression "contains a monomer unit" in a polymer means "a structural unit derived from the monomer is contained in the polymer obtained using the monomer”.
• the content ratio of monomer units in the polymer can be measured using a nuclear magnetic resonance (NMR) method such as 1 H-NMR.
• NMR nuclear magnetic resonance
• (meth)acrylic means acrylic and/or methacryl.
• the content ratio of polymerization initiator decomposition products in the particles constituting the particulate polymer is as follows with respect to the total mass of the particles constituting the particulate polymer: It is preferably 20 ppm or less.
• the content of the decomposed product of the polymerization initiator in the particles is below the above upper limit, the blocking resistance of the functional layer can be improved.
• the amount of polymerization initiator decomposition products that may cause an increase in resistance value eluted into the electrolytic solution is reduced, and as a result, cycle characteristics can be improved.
• the "content ratio of polymerization initiator decomposition products" can be measured using a chromatograph. Specifically, it can be measured, for example, using the method described in the Examples of this specification.
• the composition for an electrochemical device functional layer of the present invention further contains a binder. If the electrochemical element functional layer composition further contains a binder, powder falling off can be suppressed and wet adhesion and dry adhesion can be improved.
• the binder preferably contains a (meth)acrylic acid ester monomer unit and an acid group-containing monomer unit. If the binder contains a (meth)acrylic acid ester monomer unit and an acid group-containing monomer unit, wet adhesion and dry adhesion can be further improved.
• the composition for an electrochemical device functional layer of the present invention further contains an amine compound. If the composition for an electrochemical element functional layer further contains an amine compound, it is possible to suppress spoilage and the like of the composition for an electrochemical element functional layer and improve the storage stability of the composition for an electrochemical element functional layer.
• composition for an electrochemical device functional layer of the present invention further contains non-conductive heat-resistant particles. If the composition for an electrochemical device functional layer further contains non-conductive heat-resistant particles, the heat resistance of the functional layer can be improved.
• the present invention aims to advantageously solve the above-mentioned problems, and the present invention provides a laminate for an electrochemical device, comprising a base material and a functional layer formed on the base material.
• the present invention is a laminate for an electrochemical device, in which the functional layer uses the composition for an electrochemical device functional layer. With such a laminate for an electrochemical device, the cycle characteristics of an electrochemical device including the laminate for an electrochemical device can be improved.
• the present invention aims to advantageously solve the above-mentioned problems, and the present invention is an electrochemical device including the above-mentioned laminate for an electrochemical device.
• Such an electrochemical element can exhibit excellent cycle characteristics.
• the present invention it is possible to provide a composition for an electrochemical device functional layer that can form a functional layer with excellent wet adhesion. Further, according to the present invention, it is possible to provide a laminate for an electrochemical device including a functional layer formed using the composition for an electrochemical device functional layer, and an electrochemical device including this laminate for an electrochemical device.
• the electrochemical device functional layer composition of the present invention (hereinafter also simply referred to as “functional layer composition”) is the electrochemical device laminate (hereinafter also simply referred to as "laminate") of the present invention. ) can be used as a material when forming a functional layer.
• the laminate for electrochemical devices of the present invention can be used for manufacturing the electrochemical device of the present invention.
• composition for an electrochemical device functional layer of the present invention contains a predetermined particulate polymer, and may optionally further contain a binder, non-conductive heat-resistant particles, an amine compound, and other components. With such a functional layer composition, a functional layer with excellent wet adhesion can be formed.
• the functional layer composition of the present invention is usually a slurry composition in which a particulate polymer is dispersed in water as a dispersion medium.
• the particulate polymer contained in the functional layer composition has a predetermined volume particle diameter D50 and a predetermined particle size distribution ⁇ , as detailed below. It is a polymer having the shape of Note that the particulate polymer may be in the form of particles or in any other shape after the members are bonded together via the functional layer formed using the functional layer composition. . Furthermore, the particulate polymer may be a crystalline polymer, an amorphous polymer, or a mixture thereof.
• the particulate polymer has a volume particle diameter D50 of 1.0 ⁇ m or more and 10.0 ⁇ m or less. If the volumetric particle diameter D50 of the particulate polymer is equal to or larger than the above lower limit, the particulate polymer will not react with materials other than the particulate polymer on the surface in the thickness direction of the functional layer formed using the functional layer composition. As a result, the functional layer can exhibit excellent wet adhesion and dry adhesion.
• the volume particle diameter D50 of the particulate polymer is below the above upper limit, in the functional layer formed using the functional layer composition, the bonding point between the particulate polymer and a material other than the particulate polymer is increased, powder falling is suppressed, and as a result, the functional layer can exhibit excellent wet adhesion and dry adhesion.
• the volume particle diameter D50 of the particulate polymer is preferably 2.0 ⁇ m or more, more preferably 2.3 ⁇ m or more, even more preferably 2.5 ⁇ m or more, and 9.0 ⁇ m or less. is preferable, more preferably 7.0 ⁇ m or less, and still more preferably 6.0 ⁇ m or less.
• the volume particle diameter D50 of the particulate polymer can be adjusted by the type and amount of metal hydroxide used in preparing the particulate polymer, as well as the method and conditions for preparing the particulate polymer. The details of the metal hydroxide will be described later.
• the proportion of particles having a particle diameter of 1.5 times or more the volume particle diameter D50 (hereinafter also referred to as "large particles") is 0.5, with the particulate polymer being 100% by volume. It has a particle size distribution ⁇ of vol% or more and 5.0 vol% or less.
• the proportion of large particles in the particulate polymer is at least the above lower limit, the functional layer can exhibit excellent wet adhesiveness and dry adhesiveness. Although the reason for this is not certain, it is presumed that when the functional layer and the electrode member were bonded together, coarse particles moderately entered into the minute irregularities existing on the surface of the electrode member.
• the functional layer can exhibit excellent wet adhesiveness and dry adhesiveness.
• the reason for this is not clear, but when the functional layer and the electrode member are bonded together, particles with a particle diameter less than 1.5 times the volume particle diameter D50 (hereinafter also referred to as "small particles") and the electrode It is presumed that this is because contact with the member could be maintained well without being hindered by large particles.
• the proportion of large particles in the particulate polymer is preferably 1.0% by volume or more, more preferably 1.5% by volume or more, and preferably 4.5% by volume or less, 4. More preferably, it is 0% by volume or less.
• the proportion of large particles in the particulate polymer can be adjusted by the type and amount of metal hydroxide used in preparing the particulate polymer, as well as the method and conditions for preparing the particulate polymer.
• the proportion of particles having a particle diameter of 3.0 times or more the volume particle diameter D50 (hereinafter also referred to as "coarse particles”) is 2.0%, with the particulate polymer being 100% by volume. It is preferable to have a particle size distribution ⁇ that is less than or equal to % by volume. If the proportion of coarse particles in the particulate polymer is below the above upper limit, the small particles in the functional layer will sufficiently contribute to adhesion with the electrode member, and as a result, wet adhesion and dry adhesion can be improved.
• the proportion of coarse particles in the particulate polymer is more preferably 1.8% by volume or less, even more preferably 1.5% by volume or less, and even more preferably 1.0% by volume or less.
• the proportion of coarse particles in the particulate polymer is, for example, 0.15% by volume or more, and may be 0.45% by volume or more.
• the proportion of coarse particles in the particulate polymer can be adjusted by the type and amount of metal hydroxide used in preparing the particulate polymer, as well as the method and conditions for preparing the particulate polymer.
• the particulate polymer preferably has an average circularity of 0.950 or more, preferably has an average circularity of 0.960 or more, preferably has an average circularity of 0.995 or less, and preferably has an average circularity of 0.995 or less. It is more preferable to have an average circularity of 990 or less. If the average circularity of the particulate polymer is equal to or higher than the above lower limit, the number of bonding points between the particulate polymer and materials other than the particulate polymer will increase in the functional layer formed using the functional layer composition. , powder falling is suppressed, and as a result, wet adhesion and dry adhesion can be improved.
• the average circularity of the particulate polymer is below the above upper limit, the state of the particulate polymer will be stabilized in the functional layer, suppressing powder falling off, and improving wet adhesion and dry adhesion. can. Note that the average circularity of the particulate polymer can be adjusted by the method and conditions for preparing the particulate polymer.
• the particulate polymer has a circularity distribution in which the proportion of particles having a circularity of less than 0.95 is less than 10% by number based on the particulate polymer. If the proportion of particles having a circularity of less than 0.95 in the particulate polymer is less than the above upper limit, there will be many bonding points between the particulate polymer and materials other than the particulate polymer in the functional layer, and the powder Falling is suppressed, and as a result, wet adhesion and dry adhesion can be improved.
• the proportion of particles having a circularity of less than 0.95 in the particulate polymer is more preferably 8% or less, and even more preferably 5% or less.
• the proportion of particles having a circularity of less than 0.95 in the particulate polymer is, for example, 0.1% or more, may be 0.5% or more, or may be 2% or more. Note that the proportion of particles having a circularity of less than 0.95 in the particulate polymer can be adjusted by the method and conditions for preparing the particulate polymer.
• the glass transition temperature (Tg) of the particulate polymer is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 55°C or higher, preferably 110°C or lower, more preferably 90°C or lower, even more preferably is below 70°C. If the glass transition temperature of the particulate polymer is equal to or higher than the above lower limit, the blocking resistance of the functional layer can be improved. On the other hand, if the glass transition temperature of the particulate polymer is below the above upper limit, good wet adhesion and dry adhesion of the functional layer can be obtained even when members are pressed and bonded together through the functional layer. Can be done.
• the amount of particulate polymer eluted into THF is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more. Even more preferably, it is 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. If the amount of elution of the particulate polymer into THF is equal to or higher than the above lower limit, the particulate polymer will be appropriately deformed at the contact surface between the functional layer formed using the functional layer composition and other layers.
• the amount of elution of the particulate polymer into THF is below the above upper limit, excessive deformation of the particulate polymer is suppressed, and as a result, the blocking resistance of the functional layer can be improved.
• the amount of components of the particulate polymer that may cause an increase in resistance value eluted into the electrolytic solution can be reduced, and as a result, the cycle characteristics of the electrochemical device can be improved. Note that the amount of elution of the particulate polymer into THF can be adjusted by adjusting the composition of particles constituting the particulate polymer.
• the polymer contained in the particles constituting the particulate polymer may have at least the volume particle diameter D50 of the particulate polymer and the proportion of large particles within the above range.
• polymer A may have at least the volume particle diameter D50 of the particulate polymer and the proportion of large particles within the above range.
• the monomer units of the polymer A include, for example, aromatic monovinyl monomer units, crosslinkable monomer units, (meth)acrylic acid ester monomer units, acid group-containing monomer units, Examples include fluorine atom-containing monomer units.
• the polymer A contains an aromatic monovinyl monomer unit and a crosslinkable monomer unit. That is, the particulate polymer is preferably composed of particles containing a polymer A containing an aromatic monovinyl monomer unit and a crosslinkable monomer unit. If the particulate polymer is made of particles containing polymer A containing aromatic monovinyl monomer units, wet adhesion and dry adhesion can be improved.
• aromatic monovinyl monomers that can form aromatic monovinyl monomer units include, without particular limitation, styrene, ⁇ -methylstyrene, butoxystyrene, vinylnaphthalene, etc. Among them, Styrene is preferred. Note that these aromatic monovinyl monomers may be used singly or in combination of two or more in any ratio.
• the content ratio of the aromatic monovinyl monomer unit in the polymer A is preferably 30% by mass or more, more preferably 60% by mass or more, when the total repeating units in the polymer A is 100% by mass. , preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less. If the content of the aromatic monovinyl monomer unit is at least the above lower limit, the elasticity of the particulate polymer will improve, the strength of the resulting functional layer will be ensured, and the adhesion between the functional layer and the base material will be improved. Can be done.
• the content of the aromatic monovinyl monomer unit is below the above upper limit, the flexibility of the particulate polymer will increase, and the film-forming properties during drying of the functional layer composition will improve. Therefore, the adhesion between the functional layer and the base material can be improved.
• monomers that can form crosslinkable monomer units include polyfunctional monomers having two or more polymerization-reactive groups in the monomer.
• polyfunctional monomers include (meth)acrylic acid allyl ester monomers such as allyl methacrylate; aromatic divinyl monomers such as divinylbenzene and divinylnaphthalene; diethylene glycol dimethacrylate and ethylene glycol dimethacrylate.
• di(meth)acrylic ester monomers such as diethylene glycol diacrylate and 1,3-butylene glycol diacrylate
• tri(meth)acrylic ester monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate
• Examples include ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate.
• divinylbenzene is preferable as the aromatic divinyl monomer
• ethylene glycol dimethacrylate is preferable as the di(meth)acrylate monomer
• trimethylolpropane is preferable as the tri(meth)acrylate monomer.
• Trimethacrylate is preferred, and as the ethylenically unsaturated monomer containing an epoxy group, glycidyl methacrylate is preferred. Note that these crosslinkable monomers may be used alone or in combination of two or more in any ratio.
• the crosslinkable monomer units include an aromatic divinyl monomer unit, a di(meth)acrylate monomer unit, a tri(meth)acrylate monomer unit, and an ethylene containing an epoxy group. It is preferable that the crosslinkable monomer unit is at least one type of crosslinkable monomer unit selected from the group consisting of sexually unsaturated monomer units. That is, the particulate polymer contains an aromatic divinyl monomer unit, a di(meth)acrylate monomer unit, a tri(meth)acrylate monomer unit, and an ethylenically unsaturated polymer containing an epoxy group.
• the particles include a polymer A containing at least one crosslinkable monomer unit selected from the group consisting of monomer units. If the particulate polymer is made of particles containing the polymer A containing the above-mentioned crosslinkable monomer unit, wet adhesion can be improved. Moreover, excessive deformation of the particulate polymer is suppressed, and as a result, the blocking resistance of the functional layer can be improved. Furthermore, in the electrochemical device, the amount of components of the particulate polymer that may cause an increase in resistance value eluted into the electrolyte solution can be reduced, and as a result, the cycle characteristics of the electrochemical device can be improved.
• crosslinkable monomer units can further improve the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device, so aromatic divinyl monomer units, di(meth)acrylic acid ester monomer units, More preferably, it is at least one crosslinkable monomer unit selected from the group consisting of (meth)acrylic acid ester monomer units. Furthermore, since the crosslinkable monomer unit can satisfactorily balance wet adhesion and dry adhesion and the swelling property of the functional layer into the electrolyte, aromatic divinyl monomer units and di(meth)acrylic acid More preferably, it is at least one of ester monomer units.
• the content of crosslinkable monomer units in polymer A is preferably 0.1% by mass or more, more preferably 0.3% by mass, when the total repeating units in polymer A are 100% by mass.
• the content is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less.
• the content of the crosslinkable monomer unit is at least the above lower limit, the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device can be improved.
• the content of the crosslinkable monomer unit is below the above upper limit, the particulate polymer will be moderately distributed at the contact surface between the electrochemical element member and the functional layer formed using the functional layer composition. As a result, wet adhesion and dry adhesion can be improved.
• (meth)acrylate monomers that can form the (meth)acrylate monomer unit include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-butyl acrylate.
• butyl acrylate such as acrylate, octyl acrylate such as pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, acrylic acid alkyl ester such as nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate; and methyl Methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate such as n-butyl methacrylate and t-butyl methacrylate, octyl methacrylate such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacryl
• n-butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate are preferred, and 2-ethylhexyl acrylate is more preferred.
• these (meth)acrylic acid ester monomers may be used individually, and may be used in combination of 2 or more types in arbitrary ratios.
• the content ratio of (meth)acrylic acid ester monomer units in polymer A is preferably 10% by mass or more, more preferably 15% by mass, when the total repeating units in polymer A are 100% by mass.
• the content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less. If the content ratio of the (meth)acrylic acid ester monomer unit is equal to or higher than the above lower limit, the glass transition temperature of the particulate polymer will be prevented from decreasing excessively, and the blocking resistance of the resulting functional layer will be improved. can. On the other hand, if the content of the (meth)acrylic acid ester monomer unit is below the above upper limit, good adhesion between the functional layer and the base material can be achieved.
• (meth)acrylic acid ester monomer includes those listed as the “crosslinking monomer” mentioned above and the “acid group-containing monomer” mentioned below. It does not include those that are.
• acid group-containing monomers that can form acid group-containing monomer units include monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and , a monomer having a hydroxyl group.
• Examples of the monomer having a carboxylic acid group include monocarboxylic acids, dicarboxylic acids, and the like.
• Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid.
• Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.
• Examples of monomers having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, ethyl (meth)acrylate-2-sulfonate, and 2-acrylamido-2-methylpropanesulfone. acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and the like.
• (meth)allyl means allyl and/or methallyl.
• monomers having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.
• (meth)acryloyl means acryloyl and/or methacryloyl.
• Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.
• these acid group-containing monomers may be used alone or in combination of two or more types in any ratio.
• the content ratio of acid group-containing monomer units in polymer A is preferably 0.05% by mass or more, more preferably 0.1% by mass, when the total repeating units in polymer A are 100% by mass. % or more, more preferably 0.15% by mass or more, preferably 2% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less.
• fluorine atom-containing monomers that can form fluorine atom-containing monomer units include, but are not particularly limited to, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, vinyl trifluoride chloride, and fluorine atom-containing monomer units. Examples include vinyl oxide, perfluoroalkyl vinyl ether, and the like. Among them, vinylidene fluoride is preferred. Note that these fluorine atom-containing monomers may be used alone or in combination of two or more in any ratio.
• the particulate polymer uses vinylidene fluoride as the fluorine atom-containing monomer.
• a fluorine atom-containing polymer is preferred.
• examples of the fluorine atom-containing polymer include (i) a homopolymer of vinylidene fluoride, (ii) a copolymer of vinylidene fluoride and another fluorine atom-containing monomer copolymerizable with the vinylidene fluoride.
• PVdF polyvinylidene fluoride
• PTFE polytetrafluoroethylene
• PVdF-HFP vinylidene fluoride-hexafluoropropylene copolymer
• PVdF-HFP vinylidene fluoride-hexafluoropropylene copolymer
• Polymer A includes aromatic monovinyl monomer units, crosslinkable monomer units, (meth)acrylic acid ester monomer units, acid group-containing monomer units, and others other than fluorine atom-containing monomer units. may contain monomeric units.
• other monomer units are not particularly limited, but include, for example, nitrile group-containing monomer units.
• nitrile group-containing monomers that can form nitrile group-containing monomer units include ⁇ , ⁇ -ethylenically unsaturated nitrile monomers.
• the ⁇ , ⁇ -ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an ⁇ , ⁇ -ethylenically unsaturated compound having a nitrile group, but examples include acrylonitrile; ⁇ -chloroacrylonitrile; Examples include ⁇ -halogenoacrylonitrile such as ⁇ -bromoacrylonitrile; ⁇ -alkyl acrylonitrile such as methacrylonitrile and ⁇ -ethyl acrylonitrile; and the like. Note that these nitrile group-containing monomers may be used singly or in combination of two or more in any ratio.
• the content of the nitrile group-containing monomer unit in the polymer A is preferably 3% by mass or more, and preferably 4% by mass or more, when the total repeating units in the polymer A are 100% by mass. It is more preferably 6% by mass or more, even more preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less. If the content of the nitrile group-containing monomer unit is at least the above lower limit, the binding force of the particulate polymer can be improved and the peel strength of the functional layer can be increased. On the other hand, if the content of the nitrile group-containing monomer unit is below the above upper limit, the flexibility of the particulate polymer can be improved.
• the content ratio of other monomer units other than the nitrile group-containing monomer unit in polymer A is preferably 0% by mass or more when the total repeating units in polymer A are 100% by mass. , preferably 10% by mass or less, more preferably 7% by mass or less, still more preferably 5% by mass or less. If the content ratio of other monomer units is below the above-mentioned upper limit, it is possible to suppress the stability of the functional layer composition from decreasing.
• the content of the particulate polymer in the functional layer composition is preferably 5% by mass or more, and preferably 10% by mass or more, based on all components (including the dispersion medium) in the functional layer composition. It is more preferable that the amount is at most 50% by mass, more preferably at most 40% by mass. If the content rate of the particulate polymer in the functional layer composition is at least the above lower limit, wet adhesion and dry adhesion can be improved. On the other hand, if the content of the particulate polymer in the functional layer composition is below the above upper limit, the storage stability of the functional layer composition can be improved.
• the content ratio of the particulate polymer in the composition for a functional layer is the same as that of the particulate polymer, the binder and the non-conductive heat-resistant particles. It is preferably 1% by mass or more and 12% by mass or less based on the total amount (100% by mass) of heat-resistant particles.
• Particles containing polymer A can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water.
• the proportion of each monomer in the monomer composition is usually the same as the proportion of each monomer unit in Polymer A.
• the polymerization mode is not particularly limited, and any method such as a suspension polymerization method, an emulsion polymerization aggregation method, and a pulverization method can be used. Among these, suspension polymerization and emulsion polymerization aggregation are preferred, and suspension polymerization is more preferred, from the viewpoint of ease of adjusting the volume particle diameter D50 and particle size distribution ⁇ of the particulate polymer. Further, as the polymerization reaction, any reaction such as radical polymerization or living radical polymerization can be used.
• the monomer composition used to prepare particles containing polymer A includes a chain transfer agent, a polymerization modifier, a polymerization reaction retarder, a reactive fluidizing agent, a filler, a flame retardant, an antiaging agent, and a coloring agent.
• Other compounding agents such as additives can be added in arbitrary amounts.
• the monomer composition is dispersed in water, a polymerization initiator is added, and then droplets of the monomer composition are formed.
• the droplets can be formed, for example, by shearing and stirring water containing the monomer composition using a dispersing machine such as an emulsifying dispersing machine.
• the rotation speed of the dispersion machine is preferably more than 8000 rpm, more preferably 9500 rpm or more, even more preferably 11000 rpm or more, and preferably less than 15000 rpm.
• the speed is preferably 14,000 rpm or less, more preferably 13,000 rpm or less. If the rotation speed of the disperser is within the above range, the volume particle diameter D50 and the ratio of the particle size distribution ⁇ of the particulate polymer can be easily adjusted.
• the stirring speed of the disperser is preferably 21 m/s or more, more preferably 25 m/s or more, even more preferably 29 m/s or more, It is preferably 40 m/s or less, more preferably 37 m/s or less, even more preferably 35 m/s or less. If the stirring speed of the disperser is within the above range, the volume particle diameter D50 and the ratio of particle size distribution ⁇ of the particulate polymer can be easily adjusted.
• “stirring speed” means the peripheral speed of the outer peripheral portion formed when the dispersing teeth, stirring blades, etc. rotate.
• polymerization initiator examples include oil-soluble polymerization initiators such as t-butylperoxy-2-ethylhexanoate and azobisisobutyronitrile.
• the polymerization initiator may be added after the monomer composition is dispersed in water but before forming droplets, or may be added to the monomer composition before being dispersed in water.
• a water-soluble polymerization initiator such as potassium persulfate can be used as the polymerization initiator.
• a dispersion stabilizer to water to form droplets of the monomer composition.
• a metal hydroxide such as magnesium hydroxide, sodium dodecylbenzenesulfonate, etc.
• the dispersion stabilizer may be added, for example, in the form of a colloidal dispersion in which the dispersion stabilizer is dispersed in water.
• the water containing the formed droplets is heated to start polymerization, thereby forming particles containing polymer A in the water. be done.
• the polymerization reaction temperature is preferably 50°C or more and 95°C or less.
• the reaction time of polymerization is preferably 1 hour or more, preferably 10 hours or less, more preferably 8 hours or less, and even more preferably 6 hours or less.
• the particles constituting the particulate polymer may contain a decomposed product of the polymerization initiator used in the polymerization of Polymer A (hereinafter also simply referred to as "polymerization initiator decomposed product").
• the polymerization initiator decomposition products include, in addition to the decomposition products that may exist immediately after the polymerization reaction, products after post-treatments such as decarboxylation treatment and denitrification treatment.
• examples of the polymerization initiator decomposition product include heptyl-t-butyl ether.
• examples of the decomposed product of the polymerization initiator include tetramethylsuccinitrile, 2-cyanopropane, and the like.
• examples of decomposed products of the polymerization initiator include sulfate ions (potassium sulfate).
• the content ratio of polymerization initiator decomposition products in the particles constituting the particulate polymer is preferably 20 ppm or less, more preferably 10 ppm or less, and 5 ppm or less based on the total mass of the particles. More preferably, it is 0 ppm, and particularly preferably 0 ppm.
• the content of the decomposed product of the polymerization initiator in the particles is below the above upper limit, the blocking resistance of the functional layer can be improved.
• the amount of polymerization initiator decomposition products that may cause an increase in resistance value eluted into the electrolytic solution is reduced, and as a result, cycle characteristics can be improved. Note that the content ratio of the decomposed product of the polymerization initiator in the particles can be adjusted by the purification method, purification conditions, etc. when preparing the particulate polymer.
• the composition for a functional layer of the present invention further contains a binder. If the functional layer composition further contains a binder, powder falling-off can be suppressed and wet adhesion and dry adhesion can be improved.
• the shape of the binder may be particulate or non-particulate; however, from the viewpoint of satisfactorily suppressing powder fall-off, the shape of the binder is preferably particulate.
• the binding material may be in the form of particles or any other shape after the members are bonded to each other via the functional layer formed using the composition for functional layer.
• the binder is not particularly limited, and includes known polymers that are water-insoluble and dispersible in a dispersion medium such as water, such as a binder resin such as a thermoplastic elastomer.
• a binder resin such as a thermoplastic elastomer.
• thermoplastic elastomer conjugated diene polymers and acrylic polymers (ACL) are preferred. Note that these binders may be used alone or in combination of two or more in any ratio.
• the acrylic polymer refers to a polymer containing (meth)acrylic acid ester monomer units.
• the acrylic polymer is not particularly limited, and may contain, for example, the above-mentioned crosslinkable monomer units, acid group-containing monomer units, etc. in addition to the (meth)acrylic acid ester monomer unit. You can.
• the acrylic polymer preferably contains a (meth)acrylic acid ester monomer unit and an acid group-containing monomer unit because it can improve wet adhesion and dry adhesion.
• the (meth)acrylic acid ester monomer unit, the crosslinkable monomer unit, and the acid group-containing monomer unit have been described above, their explanation will be omitted below.
• the proportion of (meth)acrylic acid ester monomer units in the acrylic polymer is preferably 50% by mass or more, more preferably is 55% by mass or more, more preferably 58% by mass or more, preferably 98% by mass or less, more preferably 97% by mass or less, still more preferably 96% by mass or less. If the ratio of the (meth)acrylic acid ester monomer unit is at least the above-mentioned lower limit, wet adhesiveness and dry adhesiveness can be further improved. On the other hand, if the proportion of the (meth)acrylic acid ester monomer unit is below the above upper limit, the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device can be improved.
• the proportion of acid group-containing monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably The content is 0.3% by mass or more, more preferably 0.5% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less.
• the proportion of the acid group-containing monomer unit is at least the above-mentioned lower limit, the dispersibility of the binder in the functional layer composition and the functional layer can be improved, and wet adhesion and dry adhesion can be further improved.
• the proportion of the acid group-containing monomer unit is below the above upper limit, the residual moisture content of the functional layer can be reduced, and the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device can be improved.
• the proportion of crosslinkable monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably 1% by mass, when the total repeating units in the polymer constituting the binder are 100% by mass. 0% by mass or more, preferably 3.0% by mass or less, more preferably 2.5% by mass or less.
• the proportion of the crosslinkable monomer unit is at least the above lower limit, the blocking resistance of the functional layer and the cycle characteristics of the electrochemical device can be improved.
• the proportion of the crosslinkable monomer unit is below the above upper limit, wet adhesion and dry adhesion can be further improved.
• the acrylic polymer may also contain other monomer units.
• Other monomers that can form other monomer units that can be included in the acrylic polymer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1 , 3-butadiene, 2-chloro-1,3-butadiene and other conjugated diene monomers; the above-mentioned aromatic monovinyl monomers; the above-mentioned acrylonitrile and other nitrile group-containing monomers; olefin monomers such as ethylene and propylene.
• Monomers containing halogen atoms such as vinyl chloride and vinylidene chloride; Vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; Vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc. vinyl ketone monomers such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; and heterocycle-containing vinyl compound monomers such as N-vinylpyrrolidone, vinylpyridine, and vinylimidazole. Examples include mercury. Among these, acrylonitrile is preferred as the other monomer. Note that these other monomers may be used alone or in combination of two or more in any ratio. Moreover, the content ratio of other monomer units in the acrylic polymer may be adjusted as appropriate.
• the proportion of other monomer units in the acrylic polymer is preferably less than 30% by mass, and 15% by mass when the total repeating units in the polymer constituting the binder are 100% by mass. It is more preferably less than 10% by mass, and still more preferably 10% by mass or less.
• the conjugated diene polymer refers to a polymer containing conjugated diene monomer units.
• Specific examples of the conjugated diene polymer include, without particular limitation, copolymers containing aromatic monovinyl monomer units and conjugated diene monomer units, such as styrene-butadiene copolymer (SBR). , butadiene rubber (BR), acrylic rubber (NBR) (a copolymer containing an acrylonitrile unit and a butadiene unit), and hydrides thereof.
• SBR styrene-butadiene copolymer
• BR butadiene rubber
• NBR acrylic rubber
• the proportion of conjugated diene monomer units in the conjugated diene polymer is preferably 15% by mass or more, more preferably 30% by mass, when the total repeating units in the polymer constituting the binder are 100% by mass. % or more, preferably 80% by mass or less, more preferably 60% by mass or less, still more preferably 40% by mass or less.
• the proportion of aromatic monovinyl monomer units in the conjugated diene polymer is preferably 15% by mass or more, more preferably 35% by mass, when the total repeating units in the polymer constituting the binder are 100% by mass. It is at least 55% by mass, more preferably at least 55% by mass, and preferably at most 80% by mass, more preferably at most 70% by mass.
• the conjugated diene polymer may contain other monomer units.
• Other monomers that can form other monomer units that can be included in the conjugated diene polymer include the above-mentioned acid group-containing monomers; the above-mentioned nitrile group-containing monomers; Can be mentioned. Note that these other monomers may be used alone or in combination of two or more in any ratio. Moreover, the content ratio of other monomer units in the conjugated diene polymer may be adjusted as appropriate.
• the glass transition temperature (Tg) of the binder is preferably -100°C or higher, more preferably -90°C or higher, even more preferably -80°C or higher, preferably lower than 30°C, more preferably 20°C or lower, More preferably, the temperature is 15°C or lower. If the glass transition temperature of the binder is equal to or higher than the above lower limit, wet adhesion and dry adhesion can be further improved. Moreover, the blocking resistance of the functional layer can be improved. On the other hand, if the glass transition temperature of the binder is below the above upper limit, the flexibility of the functional layer can be further improved.
• volume particle diameter D50 of binder is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, preferably 0.8 ⁇ m or less, and more preferably 0.5 ⁇ m or less. preferable. If the volume particle diameter D50 of the binder is equal to or larger than the above lower limit, it is possible to further suppress a decrease in the ionic conductivity in the functional layer and improve the electrochemical properties (especially output properties) of the electrochemical element. On the other hand, if the volume particle diameter D50 of the binder is below the above upper limit, wet adhesiveness and dry adhesiveness can be further improved.
• the volume particle diameter D50 of the binder is the particle diameter at which the cumulative volume calculated from the small diameter side is 50% in the particle size distribution (volume basis) obtained by measurement by laser diffraction method. and can be measured according to the methods described in the Examples herein.
• the content of the binder in the functional layer composition is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, per 100 parts by mass of the particulate polymer. is 80 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 60 parts by mass or less.
• the content of the binder is equal to or higher than the above lower limit, powder falling is suppressed, and as a result, wet adhesion and dry adhesion can be further improved.
• the content of the binder is below the above upper limit, it is possible to suppress the ionic conductivity of the functional layer from decreasing and the output characteristics of the resulting electrochemical device from decreasing.
• the content of the binder in the functional layer composition is preferably 0.1 parts by mass or more per 100 parts by mass of the non-conductive heat-resistant particles. , more preferably 0.2 parts by mass or more, still more preferably 0.5 parts by mass or more, even more preferably 3 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably It is 10 parts by mass or less.
• the content of the binder is equal to or higher than the above lower limit, powder falling is suppressed, and as a result, wet adhesiveness and dry adhesiveness can be further improved.
• the content of the binder is equal to or less than the above upper limit, it is possible to suppress the ionic conductivity of the functional layer from decreasing and to suppress the output characteristics of the resulting electrochemical device from decreasing.
• the binder is not particularly limited, and can be prepared, for example, by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water.
• the proportion of each monomer in the monomer composition is usually the same as the proportion of each monomer unit in the binder.
• the polymerization method and polymerization reaction are not particularly limited, and, for example, the polymerization method and polymerization reaction mentioned in the above-mentioned method for polymerizing particulate polymers can be used.
• Non-conductive heat-resistant particles it is preferable that the composition for a functional layer of the present invention further includes non-conductive heat-resistant particles (hereinafter also referred to as "heat-resistant particles"). If the functional layer composition further contains heat-resistant particles, the heat resistance of the functional layer can be improved.
• non-conductive heat-resistant particles means non-conductive conductive fine particles with a heat-resistant temperature of 200°C or higher
• heat-resistant temperature refers to substantial physical changes such as thermal deformation. It means the temperature that does not cause
• the heat-resistant particles are not particularly limited as long as they have a heat resistance temperature of 200° C. or higher, are electrochemically stable, and have electrical insulation properties, but inorganic particles are preferred. Since inorganic particles have a relatively high specific gravity, for example, when a functional layer composition containing inorganic particles is coated on a base material to form a functional layer, the particulate form is larger than that of the inorganic particles on the surface in the thickness direction of the functional layer. The polymer is more likely to protrude, and as a result, wet adhesion and dry adhesion can be improved.
• the material for the inorganic particles is preferably one that exists stably in the environment in which the electrochemical element is used and is electrochemically stable, such as aluminum oxide (alumina), aluminum oxide hydrate (boehmite), etc. (AlOOH)), gibbsite (Al(OH 3 )), silicon oxide, magnesium oxide (magnesia), magnesium hydroxide, calcium oxide, titanium oxide (titania), barium titanate (BaTiO 3 ), zirconium oxide (ZrO), Oxide particles such as alumina-silica composite oxide; Nitride particles such as aluminum nitride and boron nitride; Covalent crystal particles such as silicon and diamond; Hardly soluble ionic crystals such as barium sulfate, calcium fluoride, and barium fluoride Particles; clay fine particles such as talc and montmorillonite; and the like.
• aluminum oxide alumina
• aluminum oxide hydrate aluminum oxide hydrate
• gibbsite Al(OH 3 )
• aluminum oxide aluminum oxide hydrate (boehmite), magnesium hydroxide, and barium sulfate are more preferred, and aluminum oxide is even more preferred.
• these particles may be subjected to element substitution, surface treatment, solid solution formation, etc., as necessary. Note that these inorganic particles may be used alone or in combination of two or more in any ratio.
• the volume particle diameter D50 of the heat-resistant particles is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, even more preferably 0.25 ⁇ m or more, preferably 1.5 ⁇ m or less, more preferably 1.0 ⁇ m or less, and Preferably it is 0.8 ⁇ m or less. If the volume particle diameter D50 of the heat-resistant particles is equal to or larger than the above-mentioned lower limit, the heat-resistant particles will be densely packed into the functional layer. Therefore, the decrease in ion conductivity in the functional layer can be further suppressed, and the electrochemical properties (especially output properties) of the electrochemical element can be improved.
• the volume particle diameter D50 of the heat-resistant particles means a particle diameter at which the cumulative volume calculated from the small diameter side is 50% in the particle size distribution (volume basis) obtained by measurement by laser diffraction method, It can be measured according to the method described in Examples.
• the volume ratio of the particulate polymer to the heat-resistant particles in the functional layer composition is preferably 5/95 or more, and preferably 20/80 or more. preferably 25/75 or more, even more preferably 30/70 or more, preferably 45/55 or less, more preferably 40/60 or less, 35/65 or less It is more preferable that If the volume ratio of the particulate polymer to the heat-resistant particles is within the above range, the functional layer will have a good balance between heat resistance and adhesiveness.
• the mass ratio of the shaped polymer to the heat-resistant particles in the functional layer composition is preferably 1/99 or more, and preferably 6/94 or more. is more preferable, more preferably 9/91 or more, preferably 51/49 or less, more preferably 42/58 or less, even more preferably 36/64 or less. If the mass ratio of the particulate polymer to the heat-resistant particles is within the above range, the functional layer will have a better balance between heat resistance and adhesiveness.
• the functional layer composition of the present invention further contains an amine compound. If the composition for a functional layer further contains an amine compound, the storage stability of the composition for a functional layer can be improved by suppressing spoilage of the composition for a functional layer.
• the amine compound is not particularly limited, and examples thereof include hydroxylamine sulfate, diethylhydroxylamine, dimethylhydroxylamine, dipropylhydroxylamine, isopropylhydroxylamine, and isothiazoline compounds.
• isothiazoline compounds are preferred because they can further improve the storage stability of the functional layer composition.
• examples of the isothiazoline compound include 1,2-benzo-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and the like. These amine compounds may be used alone or in combination of two or more in any ratio.
• the content of the amine compound is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 2 parts by mass or less, more preferably 1 part by mass, per 100 parts by mass of the particulate polymer. It is as follows.
• the functional layer composition may contain any other components in addition to the particulate polymer, the binder, the non-conductive heat-resistant particles, and the amine compound.
• Other components are not particularly limited as long as they do not affect the electrochemical reaction in the electrochemical element, and include known additives such as dispersants, viscosity modifiers, and wetting agents. These other components may be used alone or in combination of two or more.
• the method for preparing the composition for the functional layer is not particularly limited.
• the particulate polymer described above, water as a dispersion medium, a binder used as necessary, heat-resistant particles, and an amine can be prepared by mixing the compound and other ingredients.
• a particulate polymer or a binder is prepared by polymerizing a monomer composition in an aqueous solvent, the particulate polymer or binder can be directly mixed with other components in the state of an aqueous dispersion. May be mixed with
• water in the aqueous dispersion may be used as a dispersion medium.
• the method of mixing the above-mentioned components is not particularly limited, but in order to efficiently disperse each component, it is preferable to perform the mixing using a disperser as a mixing device.
• the dispersing machine is preferably a device that can uniformly disperse and mix the above components. Examples of the dispersing machine include a ball mill, a sand mill, a pigment dispersing machine, a crusher, an ultrasonic dispersing machine, a homogenizer, and a planetary mixer.
• the laminate for an electrochemical device of the present invention includes a base material and a functional layer formed on the base material, and the functional layer is formed using the composition for a functional layer of the present invention. Since the functional layer composition of the present invention can form a functional layer with excellent wet adhesion, a laminate including a functional layer using the composition improves the cycle characteristics of an electrochemical device including such a laminate. can.
• the base material is not particularly limited, and for example, when a functional layer is used as a member that constitutes a part of a separator, a separator base material can be used as the base material, and a separator base material that constitutes a part of an electrode can be used as the base material.
• a functional layer As a member, an electrode base material formed by forming an electrode mixture layer on a current collector can be used as the base material.
• the laminate obtained by forming a functional layer on a base material using the composition for a functional layer For example, a functional layer is formed on a separator base material, etc., and then electrochemically used as a separator, etc. It may be used as an element member, or a functional layer may be formed on an electrode base material and used as an electrode as it is.
• the separator base material forming the functional layer is not particularly limited, and for example, those described in JP-A-2012-204303 can be used. Among these, polyolefin-based ( A microporous membrane made of a resin such as polyethylene, polypropylene, polybutene, or polyvinyl chloride is preferred. Note that the separator base material may include, as a part thereof, any layer other than the functional layer that can exhibit the intended function.
• the electrode base material (positive electrode base material and negative electrode base material) forming the functional layer is not particularly limited, but includes an electrode base material in which an electrode mixture layer is formed on a current collector.
• the current collector the components in the electrode composite layer (for example, the electrode active material (positive electrode active material, negative electrode active material) and the binder for the electrode composite layer (the binder for the positive electrode composite layer, the negative electrode composite material),
• the electrode base material may include, as a part thereof, any layer having an intended function other than the functional layer.
• the functional layer can be formed on the above-mentioned base material using the functional layer composition of the present invention.
• the functional layer contains at least the particulate polymer described above, a binder used as necessary, heat-resistant particles, an amine compound, and other components.
• each component contained in the functional layer was contained in the above-mentioned composition for functional layer, and the preferred abundance ratio of each component is determined based on the proportion of each component in the composition for functional layer. The same as the preferred abundance ratio.
• the method of forming a functional layer on a base material using a composition for a functional layer is not particularly limited, and for example, 1) A method in which the functional layer composition is applied to the surface of the above-mentioned base material and then dried 2) A method in which the above-mentioned base material is immersed in the functional layer composition and then dried 3) Functional layer composition
• An example of this method is to apply the above-described functional layer onto a release substrate, dry it to form a functional layer, and transfer the obtained functional layer onto the surface of the above-mentioned substrate.
• the functional layer may be formed only on one side of the base material, or may be formed on both sides of the base material.
• the mold release base material is not particularly limited, and any known mold release base material can be used.
• method 1) above is preferable because it allows easy control of the thickness of the functional layer.
• the method 1) above includes, for example, a step of applying a composition for a functional layer onto a base material (coating step), and a step of drying the composition for a functional layer coated on the base material to form a functional layer. (functional layer formation step) may be included.
• the method for drying the functional layer composition on the base material is not particularly limited, and any known method can be used, such as drying with warm air, hot air, low humidity air, vacuum drying, infrared rays, etc.
• drying methods include irradiation with electron beams and electron beams. Drying conditions are not particularly limited, but the drying temperature is preferably 50°C or more and 150°C or less, and the drying time is preferably 1 minute or more and 30 minutes or less.
• the functional layer formed on the base material is suitable as a single layer that simultaneously functions as a heat-resistant layer that increases the heat resistance of the base material and as an adhesive layer that firmly adheres components to each other. It can be used for.
• the base material including the functional layer formed using the functional layer composition as described above that is, the laminate of the present invention, has a shorter length than the conventional base material including the heat-resistant layer and the adhesive layer.
• Productivity is high because it can be manufactured with a small number of man-hours and time.
• a plurality of heat-resistant particles are usually arranged so as to be stacked in the thickness direction of the functional layer.
• the thickness of the layer formed by stacking heat-resistant particles in the thickness direction of the functional layer (hereinafter also referred to as "heat-resistant particle layer”) is preferably 0.5 ⁇ m or more, more preferably 0.8 ⁇ m or more, and even more preferably 1 ⁇ m. or more, preferably 6 ⁇ m or less, more preferably 5 ⁇ m or less, even more preferably 4 ⁇ m or less. If the thickness of the heat-resistant particle layer is at least the above-mentioned lower limit, the heat resistance of the functional layer will be extremely good.
• the thickness of the heat-resistant particle layer is equal to or less than the above upper limit, the ion diffusivity of the functional layer can be ensured, and the electrochemical characteristics (especially output characteristics) of the electrochemical element can be further sufficiently improved.
• the thickness of a heat-resistant particle layer can be measured using the method described in the Example of this specification.
• volume particle diameter D50 of particulate polymer to thickness of heat-resistant particle layer is preferably 1.05 or more, more preferably 1.2. Above, it is more preferably 1.5 or more, preferably 5.0 or less, more preferably 4.5 or less, still more preferably 4.0 or less.
• the ratio of the volume particle diameter D50 of the particulate polymer to the thickness of the heat-resistant particle layer is at least the above lower limit, the particulate polymer will more easily protrude from the surface of the heat-resistant particles on the surface of the functional layer in the thickness direction. , even better wet adhesion and dry adhesion can be exhibited.
• the ratio of the volumetric particle diameter D50 of the particulate polymer to the thickness of the heat-resistant particle layer is below the above upper limit, the particulate polymer is further prevented from falling off when applying the functional layer composition to the base material. It is possible to suppress this and form a more uniform functional layer.
• the thickness of the functional layer formed on the base material (hereinafter also referred to as "maximum thickness of the functional layer”) is preferably 1.0 ⁇ m or more, more preferably 1.5 ⁇ m or more, even more preferably 2.0 ⁇ m or more, It is particularly preferably 2.5 ⁇ m or more, most preferably 5.0 ⁇ m or more, preferably 10.0 ⁇ m or less, more preferably 9.0 ⁇ m or less, and still more preferably 8.0 ⁇ m or less. If the maximum thickness of the functional layer is at least the above lower limit, the heat resistance of the functional layer will be extremely good.
• the maximum thickness of the functional layer is equal to or less than the above upper limit, the ion diffusivity of the functional layer can be ensured, and the electrochemical characteristics (especially output characteristics) of the electrochemical element can be further sufficiently improved.
• the "maximum thickness of the functional layer” can be measured using, for example, a field emission scanning electron microscope (FE-SEM).
• the electrochemical device of the present invention includes the laminate of the present invention. Such an electrochemical element can exhibit excellent cycle characteristics.
• the electrochemical device of the present invention only needs to include at least the laminate of the present invention, and therefore may include components other than the laminate of the present invention as long as the effects of the present invention are not significantly impaired. .
• the electrochemical device of the present invention is not particularly limited, and is, for example, a lithium ion secondary battery or an electric double layer capacitor, preferably a lithium ion secondary battery.
• a lithium ion secondary battery according to the present invention includes the above-described laminate of the present invention. More specifically, the lithium ion secondary battery includes a positive electrode, a negative electrode, a separator with a functional layer (laminate of the present invention) in which the functional layer is formed on a separator base material, and an electrolyte. It is.
• the functional layer may be formed on only one side of the separator base material, or may be formed on both sides of the separator base material. In addition, in the following example, the functional layer is formed on the separator base material, but the functional layer may be formed on the electrode base material.
• the positive electrode and the separator base material and/or the negative electrode and the separator base material are firmly adhered to each other in the electrolytic solution by the functional layer. Therefore, the expansion of the distance between the plates of the electrodes due to repeated charging and discharging is also suppressed, resulting in good battery characteristics such as cycle characteristics. Furthermore, in this lithium ion secondary battery, the functional layer improves the heat resistance of the separator base material. Furthermore, this lithium ion secondary battery can be manufactured with high productivity by shortening the time required to manufacture the separator, compared to the case where a conventional separator including a heat-resistant layer and an adhesive layer is used.
• positive electrode negative electrode
• electrolytic solution known positive electrodes, negative electrodes, and electrolytic solutions used in lithium ion secondary batteries can be used.
• Electrodes positive electrode and negative electrode
• an electrode formed by forming an electrode mixture layer on a current collector can be used.
• the current collector one made of metal materials such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, and platinum can be used.
• a current collector made of copper it is preferable to use as the current collector for the negative electrode.
• the current collector for the positive electrode it is preferable to use a current collector made of aluminum.
• the electrode mixture layer a layer containing an electrode active material and a binder can be used as the electrode mixture layer.
• a separator with a functional layer can be produced, for example, by forming a functional layer on a separator base material using the method for forming a functional layer described above.
• the separator base material is not particularly limited, and for example, those described in JP-A-2012-204303 can be used.
• an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used.
• a lithium salt is used in a lithium ion secondary battery.
• lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi. , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like.
• LiPF 6 , LiClO 4 , and CF 3 SO 3 Li are preferred because they are easily soluble in solvents and exhibit a high degree of dissociation.
• one type of electrolyte may be used alone, or two or more types may be used in combination.
• the lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.
• the organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but for example, in lithium ion secondary batteries, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC) are used. , propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (ethyl methyl carbonate (EMC)), carbonates such as vinylene carbonate; esters such as ⁇ -butyrolactone, methyl formate; 1,2-dimethoxyethane, Ethers such as tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; and the like are preferably used.
• DMC dimethyl carbonate
• EC ethylene carbonate
• DEC diethyl carbonate
• PC propylene carbonate
• BC butylene carbonate
• EMC methyl ethyl carbonate
• carbonates such as vinylene carbon
• a mixture of these organic solvents may be used.
• carbonates are preferred because they have a high dielectric constant and a wide stable potential range.
• the lower the viscosity of the organic solvent used the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted depending on the type of organic solvent.
• concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate.
• known additives may be added to the electrolyte.
• the lithium ion secondary battery as an electrochemical device of the present invention can be produced, for example, by stacking the above-mentioned positive electrode and negative electrode via a separator with a functional layer (the laminate of the present invention), and winding this as necessary. It can be manufactured by folding it, etc., placing it in a battery container, injecting an electrolyte into the battery container, and sealing it.
• an expanded metal, a fuse, an overcurrent prevention element such as a PTC element, a lead plate, etc. may be placed in the battery container as necessary to prevent pressure increase inside the battery and overcharging and discharging.
• the shape of the battery may be, for example, a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, or the like.
• the circularity and circularity distribution, the amount of elution of the particulate polymer into THF, the content of polymerization initiator decomposition products in the particles, the thickness of the heat-resistant particle layer, and the volume ratio of the particulate polymer to the heat-resistant particles are as follows: It was measured by the following method. In addition, wet adhesion, dry adhesion, blocking resistance of the functional layer, and cycle characteristics of the secondary battery were measured and evaluated by the following methods.
• EXSTAR DSC6220 manufactured by SII Nanotechnology
• ⁇ Volume particle diameter D50 and particle size distribution ⁇ of particulate polymer> Particulate polymers prepared in Examples and Comparative Examples were used as measurement samples. An amount equivalent to 0.1 g of the measurement sample was weighed, taken into a beaker, and 0.1 mL of an aqueous alkylbenzenesulfonic acid solution (manufactured by Fujifilm, "Drywell”) was added as a dispersant. Furthermore, 10 to 30 mL of a diluent (manufactured by Beckman Coulter, "Isoton II”) was added to the above beaker, and the mixture was dispersed for 3 minutes using a 20 W (Watt) ultrasonic disperser.
• a diluent manufactured by Beckman Coulter, "Isoton II
• the particle size measuring device manufactured by Beckman Coulter, "Multisizer" under the following conditions: aperture diameter: 20 ⁇ m, medium: Isoton II, number of particles measured: 100,000.
• the particle diameter D50 at which the cumulative volume calculated from the small diameter side is 50% was defined as the volume particle diameter D50 of the particulate polymer.
• the value of volume particle diameter D50 calculates the value of volume particle diameter D50 ⁇ 1.5, and assuming that the particulate polymer is 100% by volume, the particle size has a particle diameter equal to or larger than the value of volume particle diameter D50 ⁇ 1.5.
• the proportion of particles was determined. Furthermore, from the value of the volume particle diameter D50, the value of the volume particle diameter D50 x 3.0 is calculated, and the particulate polymer has a particle diameter equal to or larger than the value of the volume particle diameter D50 x 3.0, assuming that the particulate polymer is 100% by volume. The proportion of particles (proportion of coarse particles) was determined.
• volume particle diameter D50 of binder The volume particle diameter D50 of the binder prepared in the example was measured by a laser diffraction method. Specifically, an aqueous dispersion solution (adjusted to a solid content concentration of 0.1% by mass) containing the prepared binder was used as a sample. Then, measurement was performed using a laser diffraction particle size distribution measuring device (manufactured by Beckman Coulter, "LS-230"). In the particle size distribution (volume basis) of the binder obtained in the measurement, the particle diameter D50 at which the cumulative volume calculated from the small diameter side is 50% was defined as the volumetric particle diameter D50 of the binder.
• volume particle diameter D50 of heat-resistant particles The volume particle diameter D50 of the heat-resistant particles used in Examples and Comparative Examples was measured by a laser diffraction method. Specifically, in the particle size distribution (volume basis) of heat-resistant particles obtained by measurement using a laser diffraction method, the particle diameter (D50) at which the cumulative volume calculated from the small diameter side is 50% is defined as the volume particle diameter of the heat-resistant particles. It was set as D50.
• Circularity Perimeter of a circle equal to the projected area of the particulate polymer / Perimeter of the projected image of the particulate polymer ... (I)
• the number-based ratio of particles having a circularity of less than 0.95 was determined for the particulate polymer.
• ⁇ Amount of elution of particulate polymer into THF> The aqueous dispersions of particulate polymers prepared in Examples and Comparative Examples were filtered using filter paper No. 1 for quantitative analysis. 5B (manufactured by Advantech), the obtained solid content was placed in a container of a dryer, and dried at 40° C. for 48 hours to obtain a dried particulate polymer. About 0.2 g of the obtained powder was pressed at 200° C. and 5 MPa for 2 minutes to obtain a film. Thereafter, the dried film was cut into 3 to 5 mm square pieces, and approximately 1 g was accurately weighed. Let w0 be the mass of the film piece obtained by cutting.
• ⁇ Content of polymerization initiator decomposition products in particles> The aqueous dispersions of particulate polymers prepared in Examples and Comparative Examples were filtered using filter paper No. 1 for quantitative analysis. 5B (manufactured by Advantech), the obtained solid content was placed in a container of a dryer, and dried at 40° C. for 48 hours to obtain a dried particulate polymer. Approximately 1.0 g of the obtained powder was mixed with 5 g of acetone and allowed to stand at room temperature (25° C.) for 15 hours to extract the polymerization initiator decomposition product into acetone. Thereafter, the acetone containing the decomposed product of the polymerization initiator was filtered through a 0.45 ⁇ m PTFE filter.
• Example 6 the content ratio of polymerization initiator decomposition products was determined by the following method. Specifically, the aqueous dispersion of the particulate polymer prepared in Example 6 was filtered using quantitative analysis filter paper No. 5B (manufactured by Advantech), the obtained solid content was placed in a container of a dryer, and dried at 40° C. for 48 hours to obtain a dried particulate polymer. Approximately 1.0 g of the obtained powder was mixed with 5 g of water and left to stand at room temperature (25° C.) for 15 hours to extract the polymerization initiator decomposition product into water. Thereafter, the water containing the polymerization initiator decomposition product was filtered through a 0.45 ⁇ m PTFE filter.
• quantitative analysis filter paper No. 5B manufactured by Advantech
• the resulting solution (water) was analyzed using an ion chromatograph (manufactured by Thermo Fisher Scientific, product name: Integrion RFIC) to determine the decomposition product of the polymerization initiator in the particles relative to the total mass of the particles constituting the particulate polymer. The content ratio was determined.
• potassium persulfate was used as a polymerization initiator, so the polymerization initiator decomposition product was a sulfate ion.
• ⁇ Thickness of heat-resistant particle layer> A cross section of the separator with a functional layer (laminate) was observed using a field emission scanning electron microscope (FE-SEM), and the thickness of the heat-resistant particle layer was calculated from the obtained image.
• the thickness of the heat-resistant particle layer was defined as the distance in the vertical direction from the surface of the separator on which the functional layer was formed to the heat-resistant particles forming the surface of the functional layer.
• ⁇ Volume ratio of particulate polymer to heat-resistant particles From the amount of heat-resistant particles and particulate polymer charged when preparing the slurry composition (composition for functional layer), the volume ratio of particulate polymer to heat-resistant particles (volume of particulate polymer/volume of heat-resistant particles) I asked for The calculations were made assuming that the density of alumina is 4 g/cm 3 , the density of boehmite is 3.1 g/cm 3 , the density of magnesium hydroxide is 2.4 g/cm 3 , and the density of barium sulfate is 4.5 g/cm 3 .
• EC ethylene carbonate
• DEC diethyl carbonate
• Cellophane tape (specified in JIS Z1522) was attached to the surface of the positive electrode with the pressed test piece facing down on the current collector side of the positive electrode. Note that the cellophane tape was fixed on a horizontal test stand.
• peel strength (N/m) by the measurement using the above positive electrode and negative electrode, and the adhesion between the electrode and separator through the functional layer after immersion in the electrolytic solution was determined. (Wet adhesion) was evaluated using the following criteria. The higher the peel strength, the better the wet adhesion.
• D Peel strength is Less than 1.0N/m
• peel strength is 5.0 N/m or more
• adhesiveness dry adhesiveness between the electrode and the separator via the functional layer
• ⁇ Blocking resistance of functional layer> Two separators with functional layers (functional layers provided on both sides) produced in Examples and Comparative Examples were cut out into a size of 4 cm width x 4 cm length to prepare test pieces. The two obtained test pieces were stacked on top of each other so that the functional layer sides faced each other, and then pressed for 2 minutes at a temperature of 40° C. and a load of 8 kN to obtain a pressed body. One end of the obtained pressed body was fixed and the other end of the pressed body was pulled vertically upward at a tensile speed of 50 mm/min to measure the stress when peeled off, and the stress obtained was defined as the blocking strength. Then, the blocking strength was evaluated based on the following criteria.
• Blocking strength is less than 4 N/m
• Blocking strength is 4 N/m or more and less than 6 N/m
• Blocking strength is 6 N/m or more and less than 8 N/m
• Blocking strength is 8 N/m or more
• This charging and discharging at 0.2C was repeated three times. Thereafter, charging and discharging operations were performed for 200 cycles at a cell voltage of 4.20-3.00V and a charge/discharge rate of 1.0C in an environment at a temperature of 25°C.
• the discharge capacity of the first cycle was defined as X1
• the discharge capacity of the 200th cycle was defined as X2.
• Capacity retention rate ⁇ C' is 93% or more
• Example 1 ⁇ Preparation of particulate polymer (A)> [Preparation of monomer composition (A)] Mix 81.5 parts of styrene as an aromatic monovinyl monomer, 18 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, and 0.5 part of ethylene glycol dimethacrylate as a crosslinking monomer. Thus, a monomer composition (A) was prepared.
• aqueous solution (A1) obtained by dissolving 10.0 parts of magnesium chloride in 200 parts of ion-exchanged water was gradually added to an aqueous solution (A2) obtained by dissolving 7.0 parts of sodium hydroxide in 50 parts of ion-exchanged water with stirring.
• a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide was prepared.
• a particulate polymer (A) was prepared by a suspension polymerization method. Specifically, the monomer composition (A) obtained as described above is added to the colloidal dispersion (A) containing magnesium hydroxide, and after further stirring, t- 3.0 parts of butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, "Perbutyl O”) was added to obtain a mixed solution.
• the resulting mixed solution was stirred under high shear for 1 minute at a rotational speed of 12,000 rpm using an in-line emulsification dispersion machine (manufactured by Taiheiyo Kiko Co., Ltd., "Cavitron”) to form a colloidal dispersion containing magnesium hydroxide. , forming droplets of monomer composition (A).
• a colloidal dispersion containing magnesium hydroxide in which droplets of the monomer composition (A) were formed was placed in a reactor, and the temperature was raised to 90° C. to conduct a polymerization reaction for 5 hours.
• the obtained dispersion was purified by performing a reduced pressure treatment at 90° C. for 2 hours using an evaporator to obtain an aqueous dispersion containing particulate polymer (A).
• an aqueous dispersion containing the particulate polymer (A) the volume particle diameter D50 and particle size distribution ⁇ of the particulate polymer (A) were measured. The results are shown in Table 1.
• a monomer composition is prepared by mixing 2 parts of methacrylic acid as a monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, and 1 part of allyl methacrylate and 1 part of allyl glycidyl ether as crosslinkable monomers. ( ⁇ ) was prepared.
• the obtained monomer composition ( ⁇ ) was continuously added to the reactor equipped with the above-mentioned stirrer over a period of 4 hours to carry out polymerization. During the addition, the reaction was carried out at 60°C. After the addition was completed, the mixture was further stirred at 70° C. for 3 hours, and then the reaction was terminated to obtain an aqueous dispersion containing particulate binder ( ⁇ ) as an acrylic polymer.
• the resulting particulate binder ( ⁇ ) had a volume particle diameter D50 of 0.4 ⁇ m and a glass transition temperature of -40°C.
• composition for functional layer ⁇ Preparation of slurry composition (composition for functional layer)> Add 0.5 part of polyacrylic acid as a dispersant to 100 parts of alumina (manufactured by Sumitomo Chemical Co., Ltd., "AKP3000", volume particle diameter D50: 0.7 ⁇ m) as heat-resistant particles, and the solid content concentration becomes 55%. Ion-exchanged water was added and mixed using a ball mill, and 6 parts equivalent to the solid content of an aqueous dispersion containing the binder ( ⁇ ) were added to obtain a pre-mixing slurry.
• alumina manufactured by Sumitomo Chemical Co., Ltd., "AKP3000", volume particle diameter D50: 0.7 ⁇ m
• the volume ratio of the particulate polymer (A) to the heat-resistant particles in the slurry composition was 30/70.
• the mass ratio of the particulate polymer (A) to the heat-resistant particles in the slurry composition [mass of particulate polymer (A)/mass of heat-resistant particles] was 30/280.
• the content of polymerization initiator decomposition products in the particles and the amount of particulate polymer eluted into THF were measured. The results are shown in Table 1.
• separator with functional layer (laminate) A microporous polyethylene membrane (thickness: 12 ⁇ m) was prepared as a separator base material.
• the slurry composition obtained as described above was applied to one side of this separator base material by a bar coater method.
• the separator base material coated with the slurry composition was dried at 50° C. for 1 minute to form a functional layer.
• the same operation was performed on the other side of the separator base material to produce a separator with a functional layer (laminate) having functional layers each having a thickness of 2.0 ⁇ m on both sides of the separator base material.
• the above slurry composition for a positive electrode was applied onto a 20 ⁇ m thick aluminum foil as a current collector using a comma coater so that the film thickness after drying was about 150 ⁇ m, and dried. This drying was performed by transporting the aluminum foil at a speed of 0.5 m/min through an oven at 60° C. for 2 minutes. Thereafter, heat treatment was performed at 120° C. for 2 minutes to obtain a positive electrode original fabric before pressing. This unpressed positive electrode material was rolled with a roll press to obtain a pressed positive electrode having a positive electrode composite layer (thickness: 60 ⁇ m).
• a 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode composite layer to adjust the pH to 8, and unreacted monomers were removed by heating and vacuum distillation. Thereafter, it was cooled to 30° C. or lower to obtain an aqueous dispersion containing the desired binder for the negative electrode composite layer.
• 80 parts of artificial graphite (volume average particle diameter: 15.6 ⁇ m) as the negative electrode active material (1) and 16 parts of silicon-based active material SiOx (volume average particle diameter: 4.9 ⁇ m) as the negative electrode active material (2) were blended.
• a mixed solution was defoamed under reduced pressure to obtain a slurry composition for a negative electrode with good fluidity.
• the above slurry composition for a negative electrode was applied onto a 20 ⁇ m thick copper foil as a current collector using a comma coater so that the film thickness after drying would be about 150 ⁇ m, and then dried. This drying was carried out by transporting the copper foil in an oven at 60° C. for 2 minutes at a speed of 0.5 m/min. Thereafter, heat treatment was performed at 120° C. for 2 minutes to obtain a negative electrode original fabric before pressing. This unpressed negative electrode material was rolled with a roll press to obtain a pressed negative electrode having a negative electrode composite material layer (thickness: 80 ⁇ m).
• the obtained product was wound with a winding body to obtain a winding body.
• the opening of the aluminum packaging material exterior was closed by heat sealing at a temperature of 150° C. to produce a wound type lithium ion secondary battery with a capacity of 800 mAh.
• the cycle characteristics of the secondary battery were evaluated using the obtained lithium ion secondary battery. The results are shown in Table 1.
• Example 2 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (B) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (B) was prepared by performing the same operation as in 1.
• the colloidal dispersion containing magnesium hydroxide (B) is an aqueous solution (B1) prepared by dissolving 12.0 parts of magnesium chloride in 200 parts of ion-exchanged water, and 8.4 parts of sodium hydroxide in 50 parts of ion-exchanged water. It was prepared by gradually adding an aqueous solution (B2) obtained by dissolving 1 part of 1 part with stirring.
• Example 3 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (C) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (C) was prepared by performing the same operation as in 1.
• the colloidal dispersion containing magnesium hydroxide (C) is an aqueous solution (C1) prepared by dissolving 8.0 parts of magnesium chloride in 200 parts of ion-exchanged water, and 5.6 parts of sodium hydroxide in 50 parts of ion-exchanged water. It was prepared by gradually adding an aqueous solution (C2) obtained by dissolving 1 part of 1 part with stirring.
• Example 4 In preparing the slurry composition, various operations were performed in the same manner as in Example 1, except that the particulate polymer (D) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (D) was prepared in the same manner as in Example 1, except that the rotation speed of the disperser was changed from 12,000 rpm to 13,500 rpm.
• Example 5 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (E) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (E) was prepared in the same manner as in Example 1, except that the rotation speed of the disperser was changed from 12,000 rpm to 10,000 rpm.
• Example 6 Example 1 except that in preparing the slurry composition, the particulate polymer (F) prepared as follows using the emulsion polymerization aggregation method was used instead of the particulate polymer (A). Various operations, measurements, and evaluations were performed in the same manner. The results are shown in Table 1.
• Preparation of particulate polymer (F)> Preparation of resin fine particles In a flask, 81.5 parts of styrene as an aromatic monovinyl monomer, 18 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, and as a crosslinking monomer A monomer composition (F) was prepared by mixing 0.5 part of ethylene glycol dimethacrylate. On the other hand, in a separable flask, 0.7 parts of sodium dodecylbenzenesulfonate as an anionic surfactant was dissolved in 373 parts of ion-exchanged water to prepare a surfactant solution.
• the monomer composition (F) obtained as described above was added to the above surfactant solution, and dispersed using an emulsifying dispersion machine (M Techniques, "Clearmix”) to obtain a monomer composition.
• An emulsified dispersion of product (F) was prepared.
• an aqueous solution containing 2.1 parts of potassium persulfate as a polymerization initiator (2.1 parts of potassium persulfate was dissolved in 39.6 parts of ion-exchanged water) (an aqueous solution prepared by the above) and 1.9 parts of n-octyl mercaptan as a molecular weight regulator were added, and polymerization (first stage polymerization) was carried out at 80° C. for 3 hours.
• an aromatic monovinyl monomer was added. 81.1 parts of styrene as a monomer unit, 12.0 parts of methacrylic acid and 36.8 parts of n-butyl acrylate as (meth)acrylic acid ester monomer units, and 2.1 parts of n-octyl mercaptan as a molecular weight regulator. 1 part was added dropwise. After the dropwise addition, polymerization (second stage polymerization) was carried out by maintaining the temperature (80° C.) for 2 hours. After polymerization, the reaction solution was cooled with water to obtain a dispersion containing fine resin particles.
• the dispersion containing the above particulate polymer (F) was dehydrated, washed 10 times with ion-exchanged water, and then dried using a vacuum dryer at a pressure of 30 torr and a temperature of 50°C for 1 day. A particulate polymer (F) was obtained.
• Example 7 In preparing the slurry composition, various operations were performed in the same manner as in Example 1, except that the particulate polymer (G) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• particulate polymer (G) ⁇ Preparation of particulate polymer (G)>
• styrene as an aromatic monovinyl monomer was changed from 81.5 parts to 81.8 parts
• ethylene glycol dimethacrylate as a crosslinking monomer was changed from 0.5 parts to 0.
• a particulate polymer (G) was prepared in the same manner as in Example 1 except that the amount was changed to .2 parts.
• Example 8 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (H) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• styrene as an aromatic monovinyl monomer was changed from 81.5 parts to 77 parts, and ethylene glycol dimethacrylate as a crosslinkable monomer was changed from 0.5 parts to 5 parts.
• a particulate polymer (H) was prepared in the same manner as in Example 1 except for the following changes.
• Example 9 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (I) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• Example 10 In preparing the slurry composition, various operations were performed in the same manner as in Example 1, except that the particulate polymer (J) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• styrene as an aromatic monovinyl monomer was changed from 81.5 parts to 81.9 parts, and 0.5 part of ethylene glycol dimethacrylate as a crosslinkable monomer was changed to trimethylol.
• a particulate polymer (J) was prepared in the same manner as in Example 1, except that 0.1 part of propane trimethacrylate was used.
• Example 11 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (K) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• particulate polymer (K) ⁇ Preparation of particulate polymer (K)>
• styrene as an aromatic monovinyl monomer was changed from 81.5 parts to 76.8 parts, and 0.5 part of ethylene glycol dimethacrylate as a crosslinkable monomer was replaced with glycidyl methacrylate.
• a particulate polymer (K) was prepared in the same manner as in Example 1, except that the amount was changed to 5 parts and 0.2 parts of methacrylic acid as an acid group-containing monomer was further added.
• Example 12 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (L) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (L) was prepared in the same manner as in Example 1, except that the time for the reduced pressure treatment using an evaporator was changed to 1 hour.
• Example 13 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (M) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (M) was prepared in the same manner as in Example 1, except that the reduced pressure treatment time using an evaporator was changed to 0.5 hours.
• Example 14 Example 1 except that in preparing the slurry composition, an aqueous dispersion containing the binder ( ⁇ ) prepared as follows was used instead of the aqueous dispersion containing the binder ( ⁇ ). Various operations, measurements, and evaluations were performed in the same manner. The results are shown in Table 1.
• the obtained monomer composition ( ⁇ ) was continuously added to the reactor equipped with the above-mentioned stirrer over a period of 4 hours to carry out polymerization. During the addition, the reaction was carried out at 70°C. After the addition was completed, the mixture was further stirred at 80° C. for 3 hours, and then the reaction was terminated to obtain an aqueous dispersion containing particulate binder ( ⁇ ). Using the obtained aqueous dispersion containing the binder ( ⁇ ), the volume particle diameter D50 and glass transition temperature of the binder ( ⁇ ) were measured. The volume particle diameter D50 of the binder ( ⁇ ) was 0.25 ⁇ m, and the glass transition temperature was -35°C.
• Example 15 The slurry composition was prepared in the same manner as in Example 1, except that 100 parts of alumina as heat-resistant particles was replaced with 100 parts of boehmanite (manufactured by Showa Denko K.K., "H43M", volume particle diameter D50: 0.8 ⁇ m). Various operations, measurements, and evaluations were performed. The results are shown in Table 1.
• Example 16 In preparing the slurry composition, 100 parts of alumina as heat-resistant particles were replaced with 100 parts of magnesium hydroxide (manufactured by Kamishima Chemical Industry Co., Ltd., "Magsies X-6F", volume particle diameter D50: 0.7 ⁇ m). Various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
• Example 17 Example except that in preparing the slurry composition, 100 parts of alumina as heat-resistant particles was changed to 100 parts of barium sulfate (manufactured by Takehara Chemical Co., Ltd., "TS-2", volume particle diameter D50: 0.3 ⁇ m). Various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
• Example 18 Other than changing 0.5 part of 1,2-benzo-4-isothiazolin-3-one as the amine compound to 0.5 part of 2-methyl-4-isothiazolin-3-one in preparing the slurry composition. Various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
• Example 19 Example 1 except that in preparing the slurry composition, an aqueous dispersion containing a binder ( ⁇ ) prepared as follows was used instead of an aqueous dispersion containing a binder ( ⁇ ). Various operations, measurements, and evaluations were performed in the same manner. The results are shown in Table 1.
• ⁇ Preparation of aqueous dispersion containing binder ( ⁇ )> In a reactor, 150 parts of ion-exchanged water, 25 parts of an aqueous sodium dodecylbenzenesulfonate solution (concentration 10%) as an emulsifier, 63 parts of styrene as an aromatic monovinyl monomer, and itacon as a monomer having a carboxylic acid group were added. 3.5 parts of acid, 1 part of 2-hydroxyethyl acrylate as a monomer having a hydroxyl group, and 0.5 part of t-dodecylmercaptan as a molecular weight regulator were added in this order.
• a polymerization reaction was started by adding 0.5 part of potassium persulfate as a polymerization initiator to a reactor maintained at 60°C, and the polymerization reaction was continued while stirring.
• the polymerization conversion rate reached 96%
• the mixture was cooled and 0.1 part of a hydroquinone aqueous solution (concentration 10%) as a polymerization terminator was added to terminate the polymerization reaction.
• residual monomers were removed using a rotary evaporator at a water temperature of 60° C. to obtain an aqueous dispersion of polymer B (particulate polymer).
• the volume particle diameter D50 and glass transition temperature of the binder ( ⁇ ) were measured.
• the volume particle diameter D50 of the binder ( ⁇ ) was 0.15 ⁇ m, and the glass transition temperature was 15°C.
• Example 1 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (N) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (N) was prepared in the same manner as in Example 1, except that the rotation speed of the disperser was changed from 12,000 rpm to 15,000 rpm.
• Example 2 In preparing the slurry composition, various operations were carried out in the same manner as in Example 1, except that the particulate polymer (O) prepared as follows was used instead of the particulate polymer (A). Measurement and evaluation were performed. The results are shown in Table 1.
• a particulate polymer (O) was prepared in the same manner as in Example 1, except that the rotation speed of the disperser was changed from 12,000 rpm to 8,000 rpm.
• composition for an electrochemical device functional layer that can form a functional layer with excellent wet adhesion.

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