Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/443—Particulate material
• • 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
  • C08F259/00—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00
  • C08F259/08—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions 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 a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions 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 a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions 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 a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C09D127/16—Homopolymers or copolymers of vinylidene fluoride
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a core-shell type particle, a dispersion, a coating composition, a separator, a secondary battery, and a method for producing the core-shell type particle.
• nonaqueous electrolyte secondary batteries represented by lithium ion secondary batteries and the like are widely used.
• Nonaqueous electrolyte secondary batteries are also used in hybrid vehicles combining secondary batteries and engines, and electric vehicles powered by secondary batteries, from the viewpoint of global environmental problems and energy saving. Applications are expanding.
• a separator is provided between the electrodes (positive electrode and negative electrode) of the nonaqueous electrolyte secondary battery. If a gap is formed between the electrode and the separator, the cycle life may be deteriorated. For this reason, it is required to improve the adhesiveness of adhesive portions such as electrodes and separators.
• Patent Document 1 a separator with improved adhesion to the electrode has been developed (for example, Patent Document 1).
• Patent Document 1 by providing an adhesive layer which is an aggregate layer of a predetermined amount of fine particles containing a polyvinylidene fluoride (PVDF) resin on at least one surface of a porous substrate, ion permeability and handling properties are improved.
• PVDF polyvinylidene fluoride
• the present invention has been made in view of the above problems, and an object of the present invention is to provide vinylidene fluoride particles that provide an adhesive layer in which pores on the surface of the separator are reduced even after a hot pressing step. It is in.
• the core-shell type particle according to the present invention includes a core portion and a shell portion surrounding the core portion, and the core portion is a structural unit derived from vinylidene fluoride.
• the core portion is a structural unit derived from vinylidene fluoride.
• the shell portion comprising a structural unit derived from vinylidene fluoride as a main structural unit, and a second polymer different from the first polymer,
• the second polymer has a lower melting point than the first polymer.
• a dispersion containing the core-shell type particles and the dispersion medium according to the present invention is also included in the present invention.
• a coating composition for forming a porous fluororesin layer provided on at least one surface of a separator provided between a negative electrode layer and a positive electrode layer in a secondary battery, the core-shell type according to the present invention Coating compositions containing the particles are also included in the present invention.
• a separator in which the coating composition according to the present invention is applied to at least one surface is also included in the present invention.
• a secondary battery provided with a fluororesin layer formed from the coating composition according to the present invention, wherein the fluororesin layer heat-presses the negative electrode layer, the positive electrode layer, and the separator.
• a secondary battery comprising a layer containing the second polymer formed by the step, wherein the layer containing the second polymer contains particles containing the first polymer.
• a coating composition comprising core-shell particles according to the present invention is also included in the present invention.
• a method for producing core-shell particles is a method for producing core-shell particles including a core portion and a shell portion surrounding the periphery of the core portion.
• the shell part is formed around the core part by polymerizing the monomer.
• vinylidene fluoride particles that provide an adhesive layer in which blocking of pores on the surface of the separator is reduced even after a hot pressing step.
• the “core-shell type particle” refers to a particle including a core part and a shell part surrounding the core part.
• the core part includes a first polymer having a structural unit derived from vinylidene fluoride as a main structural unit, and the core part is vinylidene fluoride particles containing the first polymer.
• the “main structural unit” refers to a structural unit that occupies the largest proportion (mol%) of the structural units constituting the polymer.
• the term “vinylidene fluoride particles” refers to polymer particles having a structural unit derived from vinylidene fluoride as a main structural unit, and the polymer includes a homopolymer of vinylidene fluoride, And copolymers of vinylidene fluoride and other monomers.
• the proportion of the structural unit derived from vinylidene fluoride in the first polymer is preferably 98 mol% or more.
• the first polymer is particularly preferably composed only of structural units derived from vinylidene fluoride.
• the first polymer may further contain a structural unit derived from a compound other than vinylidene fluoride as another structural unit constituting the first polymer.
• compounds other than vinylidene fluoride include halogenated alkyl vinyl compounds, hydrocarbon monomers, dimethacrylic acid (poly) alkylene glycol esters, diacrylic acid (poly) alkylene glycol esters, and polyvinylbenzene.
• the halogenated alkyl vinyl compound include a fluorinated alkyl vinyl compound. Specific examples include hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, tetrafluoroethylene, hexafluoroethylene, and fluoroalkyl vinyl ether. Among them, hexafluoropropylene is preferable.
• the hydrocarbon monomer include ethylene, propylene, and styrene.
• the proportion of the constitutional unit derived from the compound other than vinylidene fluoride is such that the oxidation resistance and crystallinity are From the viewpoint of reducing the risk of damage, for example, it is preferably 2 mol% or less.
• the content of the structural unit derived from the halogenated alkyl vinyl compound is 2 mol% or less, the possibility that the core part melts and collapses in the hot press step of battery production can be further reduced. it can.
• the core part may further contain a compound other than the first polymer.
• compounds other than the first polymer include halogenated alkyl vinyl compounds, hydrocarbon monomers, dimethacrylic acid (poly) alkylene glycol esters, diacrylic acid (poly) alkylene glycol esters, polyvinylbenzene, and crosslinking agents. Etc.
• examples of the halogenated alkyl vinyl compound include a fluorinated alkyl vinyl compound. Specific examples include hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, tetrafluoroethylene, hexafluoroethylene, and fluoroalkyl vinyl ether. Can be mentioned.
• the hydrocarbon monomer include ethylene, propylene, and styrene.
• the melting point of the first polymer is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and further preferably 160 ° C. or higher, from the viewpoint of ion permeability.
• fusing point of the 1st polymer which concerns on this embodiment is demonstrated in the Example mentioned later.
• the average particle diameter of the core part is not particularly limited, but is, for example, 10 nm or more and 1 ⁇ m or less.
• the measuring method of the average particle diameter of the core part in this embodiment is demonstrated in the Example mentioned later.
• the shell portion includes a second polymer whose main structural unit is a structural unit derived from vinylidene fluoride.
• a polymer different from the first polymer is used as the second polymer.
• the melting point of the second polymer is lower than the melting point of the first polymer. Therefore, the core-shell type particles have a melting point lower than that of the first polymer.
• the melting point of the core-shell type particles is preferably 145 ° C. or higher.
• the melting point of the core-shell type particles is preferably less than 164 ° C.
• the second polymer may further include a structural unit derived from a compound other than vinylidene fluoride as another structural unit constituting the second polymer.
• compounds other than vinylidene fluoride include halogenated alkyl vinyl compounds, unsaturated dibasic acids, unsaturated dibasic acid monoesters, hydrocarbon monomers, dimethacrylic acid (poly) alkylene glycol esters, and diacrylic acid. (Poly) alkylene glycol ester, polyvinylbenzene, etc. are mentioned.
• halogenated alkyl vinyl compound examples include a fluorinated alkyl vinyl compound. Specific examples include hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, tetrafluoroethylene, hexafluoroethylene, and fluoroalkyl vinyl ether. Among them, hexafluoropropylene is preferable.
• the adhesiveness can be improved in a hot press with the electrode in a state containing the electrolytic solution.
• unsaturated dibasic acids examples include fumaric acid, maleic acid, citraconic acid, and phthalic acid. By including at least one or more types of unsaturated dibasic acids among these, the adhesiveness between the electrode and the fluororesin layer and the adhesiveness between the separator and the fluororesin layer are improved.
• Examples of the unsaturated dibasic acid monoester include monomethyl fumarate, monoethyl fumarate, monomethyl maleate, monoethyl maleate, monomethyl citraconic acid, monoethyl citraconic acid, monomethyl phthalate and monoethyl phthalate.
• unsaturated dibasic acid monoesters include monomethyl fumarate, monoethyl fumarate, monomethyl maleate, monoethyl maleate, monomethyl citraconic acid, monoethyl citraconic acid, monomethyl phthalate and monoethyl phthalate.
• hydrocarbon monomer examples include ethylene, propylene, and styrene.
• the proportion of the structural unit derived from vinylidene fluoride in the second polymer is preferably 50 mol% or more, more preferably 70 mol% or more, and 90 mol% from the viewpoint of ion permeability. More preferably, it is the above. Further, from the viewpoint of adhesion, it is preferably 99 mol% or less, more preferably 98 mol% or less, and further preferably 95 mol% or less.
• the proportion of the structural unit derived from a compound other than vinylidene fluoride is not particularly limited, but oxidation resistance From the viewpoint of properties, it is preferably 12 mol% or less, more preferably 8 mol% or less, and further preferably 3 mol% or less.
• the proportion of the structural unit derived from the halogenated alkyl vinyl compound is particularly Although not limited, from the viewpoint of adhesion, it is preferably 0.5 mol% or more, more preferably 1 mol% or more, and further preferably 2 mol% or more. Further, from the viewpoint of ion permeability, it is preferably 50 mol% or less, more preferably 30 mol% or less, and further preferably 20 mol% or less.
• the structural unit derived from unsaturated dibasic acid or unsaturated dibasic acid monoester is included as another structural unit constituting the second polymer, derived from unsaturated dibasic acid and unsaturated dibasic acid monoester.
• the proportion of the structural unit is not particularly limited, but from the viewpoint of adhesion, it is preferably 0.01 mol% or more, more preferably 0.02 mol% or more, and 0.03 mol% or more. More preferably it is. Further, from the viewpoint of productivity, it is preferably 10 mol% or less, more preferably 9 mol% or less, and further preferably 8 mol% or less.
• the shell part may further contain a compound other than the second polymer.
• compounds other than the second polymer include halogenated alkyl vinyl compounds, unsaturated dibasic acids, unsaturated dibasic acid monoesters, hydrocarbon monomers, dimethacrylic acid (poly) alkylene glycol esters, Examples include diacrylic acid (poly) alkylene glycol ester, polyvinylbenzene, and a crosslinking agent.
• the halogenated alkyl vinyl compound include a fluorinated alkyl vinyl compound.
• Examples of the unsaturated dibasic acid include fumaric acid, maleic acid, citraconic acid, and phthalic acid.
• Examples of the unsaturated dibasic acid monoester include monomethyl fumarate, monoethyl fumarate, monomethyl maleate, monoethyl maleate, monomethyl citraconic acid, monoethyl citraconic acid, monomethyl phthalate and monoethyl phthalate.
• Examples of the hydrocarbon monomer include ethylene, propylene, and styrene.
• At least one of the first polymer and the second polymer contains a structural unit derived from a halogenated alkyl vinyl compound.
• the proportion of the structural unit derived from the halogenated alkyl vinyl compound in the core-shell type particle is not particularly limited, but is preferably 0.2 mol% or more. Moreover, it is preferable that it is 5 mol% or less.
• the structural unit derived from the halogenated alkyl vinyl compound is a structural unit derived from a fluorinated alkyl vinyl compound, and the structural unit derived from the fluorinated alkyl vinyl compound is contained in the second polymer. It is more preferable.
• the average particle diameter of the core-shell type particles according to the present embodiment is not particularly limited, but is, for example, 10 nm or more and 1 ⁇ m or less.
• the measuring method of the average particle diameter of the core-shell type particles according to this embodiment will be described in the examples described later.
• the core-shell type particles according to the present embodiment are suitably used as a constituent material of a coating composition applied to a separator or an electrode in a secondary battery (particularly, a nonaqueous electrolyte secondary battery), for example.
• the vinylidene fluoride particles contained in the core portion are reduced from being crushed. Can do. Therefore, blocking the holes on the surface of the separator even after the hot pressing step is reduced.
• the method for producing core-shell type particles according to the present embodiment includes a core part forming step for forming a core part containing a first polymer and a shell part forming step for forming a shell part containing a second polymer. It is out.
• the core-shell type particle according to this embodiment described above may be manufactured by the method for manufacturing the core-shell type particle according to this embodiment. Therefore, the description in the above [core-shell type particles] can be appropriately referred to the description of [method for producing core-shell type particles].
• vinylidene fluoride which is a monomer for constituting the first polymer
• the constitutional unit constituting the first polymer further includes a constitutional unit derived from a compound other than vinylidene fluoride, the vinylidene fluoride and the other compound are polymerized.
• the amount of vinylidene fluoride charged in the core part forming step is preferably 90 parts by mass or more and 92 parts by mass or more, assuming that the total amount of all monomers in the core part forming step is 100 parts by mass. More preferably, it is 95 mass parts or more. Further, only vinylidene fluoride may be used.
• the charged amount of the halogenated alkyl vinyl compound is 10 parts from the viewpoint of ion permeability, assuming that the total amount of all monomers in the core part forming step is 100 parts by mass. It is preferably no greater than part by mass, more preferably no greater than 8 parts by mass and even more preferably no greater than 5 parts by mass.
• the core part obtained by the above polymerization may be used as a dispersion containing the particles obtained in the core part forming step in the subsequent shell part forming step, or may be used for salting out, freeze pulverization, spray drying. And powdered by at least one method selected from freeze drying and the like. Further, when used as it is, it may be dispersed in the dispersion medium used for the polymerization in the core part forming step, or may be physically or chemically redispersed in a dispersion medium such as water prepared separately. . Further, the powdered core portion may be used by being physically or chemically redispersed in a dispersion medium such as water.
• a dispersion containing an untreated core part or a dispersion containing a core part treated by the above-mentioned operations, etc. is a surfactant, pH adjuster, anti-settling agent, dispersion stabilizer, corrosion inhibitor, antifungal agent, wet An agent or the like may be further included, and impurities may be removed by a dialysis membrane or an ion exchange resin.
• a monomer (such as vinylidene fluoride) for constituting the second polymer is subjected to a polymerization reaction in the dispersion containing the core part formed in the core part forming step.
• the timing for adding the monomers is not particularly limited, and all the monomers may be added before the start of the polymerization reaction, or some monomers may be added after the start of the polymerization reaction. , They may be combined.
• the first polymer particles are polymerized without penetrating these monomers.
• the second polymer surrounds the first polymer particle, not the polymer alloy particle having an IPN structure in which the first polymer and the second polymer are intertwined with each other.
• the core-shell type particles formed in can be polymerized. By this polymerization, a shell portion is formed around the core portion of the vinylidene fluoride particles. Note that the second polymer may have a lower melting point than the first polymer.
• the amount of vinylidene fluoride charged in the shell part forming step is preferably 50 parts by mass or more and preferably 60 parts by mass or more, assuming that the total amount of all monomers in the shell part forming step is 100 parts by mass. More preferably, it is more preferably 70 parts by mass or more.
• the charged amount of the halogenated alkyl vinyl compound is 5 mass from the viewpoint of adhesion, assuming that the total amount of all monomers in the shell portion forming step is 100 mass parts.
• Part or more preferably 10 parts by weight or more, more preferably 20 parts by weight or more.
• it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less.
• the amount of unsaturated dibasic acid and unsaturated dibasic acid monoester charged is the total amount of monomers in the shell formation step.
• the total amount is 100 parts by mass, from the viewpoint of adhesion, it is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and further preferably 0.03 parts by mass or more. preferable.
• it is preferable that it is 10 mass parts or less from a viewpoint of manufacturability, It is more preferable that it is 9 mass parts or less, It is further more preferable that it is 8 mass parts or less.
• the core part forming step and the shell part forming step may be performed in the same reactor or in separate reactors.
• the core portion forming step and the shell portion forming step are continuously performed in the same reactor, for example, the residual gas monomer in the reactor is purged after completion of the core portion forming step, and then used in the shell portion forming step.
• a monomer or the like may be added to the reactor.
• the method for polymerizing the first polymer and the second polymer in the core part forming step and the shell part forming step is not particularly limited, and examples thereof include conventionally known polymerization methods.
• the polymerization method include suspension polymerization, emulsion polymerization, soap-free emulsion polymerization, miniemulsion polymerization, seed emulsion polymerization, and solution polymerization. Among them, emulsion polymerization, soap-free emulsion polymerization, miniemulsion polymerization, and seed are included. Emulsion polymerization is particularly preferred.
• the method for polymerizing the first polymer and the method for polymerizing the second polymer may be the same or different.
• Emulsion polymerization is a type of radical polymerization, which involves mixing a medium such as water, a monomer that is hardly soluble in the medium, and an emulsifier (hereinafter also referred to as a surfactant), and dissolving it in the medium. This is a polymerization method performed by adding an initiator.
• a dispersion medium, a surfactant and a polymerization initiator are used in addition to vinylidene fluoride and other monomers.
• Suspension polymerization is a polymerization method in which an oil-soluble polymerization initiator is dissolved in a water-insoluble monomer in water containing a suspending agent and the like and suspended and dispersed by mechanical stirring. In suspension polymerization, polymerization proceeds in monomer droplets, whereby vinylidene fluoride particles are obtained.
• Soap-free emulsion polymerization is emulsion polymerization that is carried out without using a normal emulsifier such as that used in the above emulsion polymerization.
• Vinylidene fluoride particles obtained by soap-free emulsion polymerization are preferred because no emulsifier remains in the polymer particles.
• Mini-emulsion polymerization is a polymerization method performed by refining monomer droplets to submicron size by applying a strong shearing force using an ultrasonic oscillator or the like.
• a slightly water-soluble substance called hydrohope is added in order to stabilize the finely divided monomer droplets.
• monomer droplets are polymerized to form fine vinylidene fluoride polymer particles.
• the seed emulsion polymerization is a polymerization in which fine particles obtained by the above polymerization method are coated with a polymer composed of another monomer. Further, vinylidene fluoride and other monomers, a dispersion medium, a surfactant, a polymerization initiator, and the like are used in the fine particle dispersion.
• the dispersion medium that can be used is not particularly limited.
• a conventionally known dispersion medium can be used, but water is preferably used as the dispersion medium.
• the surfactant to be used may be any of a nonionic surfactant, a cationic surfactant, an anionic surfactant and an amphoteric surfactant, and a plurality of types may be used in combination.
• a nonionic surfactant a cationic surfactant
• an anionic surfactant and an amphoteric surfactant a plurality of types may be used in combination.
• the surfactant perfluorinated surfactants, partially fluorinated surfactants, non-fluorinated surfactants and the like conventionally used for polymerization of polyvinylidene fluoride are suitable.
• perfluoroalkylsulfonic acid and its salt perfluoroalkylcarboxylic acid and its salt
• fluorosurfactant having a fluorocarbon chain or fluoropolyether chain are preferred, and perfluoroalkylcarboxylic acid and its salt are more preferred. preferable.
• one type or two or more types can be used as the emulsifier.
• the amount of the emulsifier added is preferably 0.005 to 22 parts by mass, more preferably 0.2 to 20 parts by mass, when the total amount of all monomers used in the polymerization is 100 parts by mass.
• Polymerization initiator There is no limitation in particular as a polymerization initiator which can be used, For example, a conventionally well-known thing can be used.
• a polymerization initiator for example, a water-soluble peroxide, a water-soluble azo compound, or a redox initiator system is used.
• the water-soluble peroxide include ammonium persulfate and potassium persulfate.
• the water-soluble azo compound include AIBN and AMBN.
• redox initiator systems include ascorbic acid-hydrogen peroxide.
• the polymerization initiator is preferably a water-soluble peroxide.
• a polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
• the addition amount of the polymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 4 parts by mass, when the total amount of all monomers used in the polymerization is 100 parts by mass. preferable.
• a chain transfer agent may be used to adjust the degree of polymerization of the obtained core-shell type particles.
• the chain transfer agent include ethyl acetate, methyl acetate, diethyl carbonate, acetone, ethanol, n-propanol, acetaldehyde, propyl aldehyde, ethyl propionate, and carbon tetrachloride.
• pH adjuster examples include electrolyte substances having a buffer capacity such as sodium dihydrogen phosphate, disodium hydrogen phosphate and potassium dihydrogen phosphate, and sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide. And basic substances such as ammonia.
• an anti-settling agent e.g., a dispersion stabilizer, a corrosion inhibitor, an antifungal agent, and / or a wetting agent may be used.
• the addition amount of the other components is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 7 parts by mass, when the total amount of all monomers used in the polymerization is 100 parts by mass. preferable.
• the polymerization temperature may be appropriately selected depending on the kind of the polymerization initiator and the like.
• the polymerization temperature may be in the range of 0 to 120 ° C, preferably in the range of 20 to 110 ° C, and in the range of 40 to 100 ° C. It is more preferable that
• the polymerization pressure may be, for example, in the range of 0 to 10 MPa, preferably in the range of 0.5 to 8 MPa, and more preferably in the range of 1 to 6 MPa.
• the polymerization time is not particularly limited, but is preferably in the range of 1 to 24 hours in consideration of productivity and the like.
• the dispersion according to the present embodiment includes the core-shell type particles and the dispersion medium according to the present embodiment.
• the dispersion medium in the dispersion according to the present embodiment is preferably water, for example, but is a mixed liquid of any non-aqueous solvent miscible with water and water, and does not dissolve the vinylidene fluoride resin.
• the liquid is not particularly limited as long as it can be dispersed, suspended, or emulsified.
• non-aqueous solvent examples include amide compounds such as N-methylpyrrolidone, dimethylformamide, and N, N-dimethylacetamide; hydrocarbons such as toluene, xylene, n-dodecane, and tetralin; methanol, ethanol, isopropyl alcohol, 2 Alcohols such as ethyl-1-hexanol, 1-nonanol and lauryl alcohol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, phorone, acetophenone and isophorone; esters such as benzyl acetate, isopentyl butyrate, methyl lactate, ethyl lactate and butyl lactate; amine compounds such as o-toluidine, m-toluidine, and p-toluidine; lactones such as ⁇ -butyrolactone and ⁇ -butyrolactone; sulf
• a pH adjuster an anti-settling agent, a dispersion stabilizer, a corrosion inhibitor, an antifungal agent, and / or a wetting agent may be used.
• the content of the core-shell type particles in the dispersion according to the present embodiment is preferably 60 parts by mass or less when the total amount of the dispersion is 100 parts by mass.
• the coating composition according to the present embodiment forms a porous fluororesin layer that improves the adhesion between the electrode and the separator in a secondary battery including a negative electrode layer and a positive electrode layer (electrode) and a separator provided therebetween. It is a composition used for
• the coating composition according to the present embodiment includes core-shell type particles according to the present embodiment.
• the coating composition according to the present embodiment may contain only core-shell type particles, or may further contain a dispersion medium for dispersing the core-shell type particles.
• a dispersion medium for dispersing the core-shell type particles.
• the coating composition according to this embodiment may be the dispersion described above.
• the core-shell type particles may be pulverized by at least one method selected from salting out, freeze pulverization, spray drying, freeze drying, etc.
• the core-shell type particles thus powdered may be physically or chemically redispersed in a dispersion medium such as water to form a coating composition.
• the dispersion in which the core-shell type particles are dispersed in the dispersion medium used for the polymerization may be used as the coating composition as it is, or the core-shell type particles are physically or chemically redispersed in a dispersion medium such as water prepared separately.
• a coating composition may be used.
• the content of the dispersion medium contained in the coating composition is preferably 65 to 3500 parts by mass, and more preferably 300 to 2000 parts by mass, where the content of the core-shell type particles is 100 parts by mass. It is more preferable.
• the coating composition which concerns on this embodiment may contain the filler as needed.
• the filler include silicon dioxide (SiO 2 ), alumina (Al 2 O 3 ), titanium dioxide (TiO 2 ), calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), and magnesium oxide (MgO).
• Oxides such as zinc oxide (ZnO) and barium titanate (BaTiO 3 ); magnesium hydroxide (Mg (OH) 2 ), calcium hydroxide (Ca (OH) 2 ), zinc hydroxide (Zn (OH)) 2 ), hydroxides such as aluminum hydroxide (Al (OH) 3 ), aluminum hydroxide oxide (AlO (OH)); carbonates such as calcium carbonate (CaCO 3 ); sulfates such as barium sulfate; nitrides Clay minerals; and boehmite.
• alumina, silicon dioxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide and boehmite are preferable from the viewpoint of battery safety and coating solution stability.
• a filler may be used independently and may use 2 or more types.
• the coating composition according to this embodiment may further contain a thickener.
• a thickener By containing a thickener, the adjustment of the viscosity of the coating composition and the dispersibility of the core-shell type particles and filler can be improved.
• the thickener include cellulose compounds such as carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose; ammonium salts or alkali metal salts of the above cellulose compounds; poly (meth) acrylic acid, modified poly (meta Polycarboxylic acids such as acrylic acid; alkali metal salts of the above polycarboxylic acids; polyvinyl alcohol (co) polymers such as polyvinyl alcohol, modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers; (meth) acrylic acid, maleic Water-soluble polymers such as saponified products of copolymers of unsaturated carboxylic acids such as acids and fumaric acid and polyvinylpyrrolidon
• the content of the filler is preferably 10 to 900 parts by mass when the content of the core-shell type particles is 100 parts by mass.
• the content of the thickener is preferably 10 parts by mass or less, preferably 5 parts by mass or less, when the total amount of the core-shell type particles, the filler, and the thickener is 100 parts by mass. Is more preferable.
• the coating composition according to the present embodiment includes a surfactant, a pH adjuster, an anti-settling agent, a corrosion inhibitor, a dispersion stabilizer, an antifungal agent, a wetting agent, and / or an antifoaming agent, if necessary. May further be included.
• the fluororesin layer in the present embodiment is formed by applying the coating composition according to the present embodiment to a separator or an electrode and drying it. Specifically, first, the coating composition is applied to at least one surface of either the separator or the electrode, and the applied coating composition is dried. The dried separator and electrode are superposed, put together with the electrolytic solution and other necessary members into an exterior material, and the exterior material is hot-pressed to adhere the separator and the electrode. At this stage, the shell portion of the core-shell type particle is melted by heat to form a fluororesin layer.
• the film thickness of the fluororesin layer is not particularly limited, but is preferably 0.1 ⁇ m or more and 10 ⁇ m or less, more preferably 0.2 ⁇ m or more and 9.5 ⁇ m or less, and 0.3 ⁇ m or more and 9 ⁇ m or less. More preferably.
• the coating composition according to this embodiment is applied so that the film thickness of the fluororesin layer falls within the above range.
• Examples of the method for applying the coating composition include a doctor blade method, a reverse roll method, a comma bar method, a gravure method, an air knife method, a die coating method, and a dip coating method.
• the coating film is preferably dried in a temperature range of 40 to 150 ° C., more preferably 45 to 130 ° C., preferably for 1 to 500 minutes, more preferably 2 to 300 minutes.
• the fluororesin layer in the present embodiment may be provided between the negative electrode layer and the separator, may be provided between the separator and the positive electrode layer, or may be provided in both of them.
• the fluororesin layer in the present embodiment is an adhesive layer.
• the fluororesin layer in the present embodiment can provide sufficient adhesion between the separator and the electrode by being provided between the separator and the electrode.
• the peel strength between the separator provided with the fluororesin layer and the electrode is, for example, 0.2 to 3.5 gf / mm. The measuring method of peeling strength is demonstrated in the Example mentioned later.
• the fluororesin layer in the present embodiment includes a layer containing a second polymer that has been melted after a hot pressing process, which is a part of the manufacturing process of the nonaqueous electrolyte battery described later. That is, in one example, the fluororesin layer has a layer containing a second polymer formed by hot pressing a negative electrode layer, a positive electrode layer, and a separator. The layer containing the second polymer contains particles containing the first polymer. By having such a structure, it is reduced that the holes on the surface of the separator are blocked even after the hot pressing process. Therefore, the fluororesin layer in this embodiment is porous.
• the air permeability of the separator provided with the fluororesin layer in the present embodiment is, for example, 2000 s / 100 cc or less. A method for measuring the air permeability will be described in Examples described later.
• the separator according to this embodiment is electrically stable and does not have electrical conductivity.
• the separator according to the present embodiment uses a porous substrate having pores or voids therein and has excellent ion permeability.
• the porous substrate include polyolefin polymers (for example, polyethylene and polypropylene), polyester polymers (for example, polyethylene terephthalate), polyimide polymers (for example, aromatic polyamide polymers, polyethers).
• examples thereof include a porous film; a nonwoven fabric; glass; and paper.
• examples of the aforementioned polymer include modified polymers.
• porous substrate those containing a polyolefin polymer (for example, polyethylene, polypropylene, etc.) are preferable.
• the porous substrate preferably contains polyethylene from the viewpoint of the shutdown function, more preferably contains polyethylene and polypropylene from the viewpoint of compatibility between the shutdown function and heat resistance, and is 95% by mass or more of polyethylene. And 5% by mass or less of polypropylene.
• the thickness of the porous substrate is preferably 3 ⁇ m or more and 25 ⁇ m or less, more preferably 5 ⁇ m or more and 25 ⁇ m or less, from the viewpoint of mechanical properties and internal resistance.
• the surface of the porous substrate may be subjected to corona treatment, plasma treatment, flame treatment, or ultraviolet irradiation treatment for the purpose of improving wettability with the coating composition.
• the coating composition according to the present embodiment is applied to at least one of the surfaces facing the negative electrode layer and the positive electrode layer.
• the negative electrode layer and the positive electrode layer in the present embodiment are not particularly limited, and for example, known negative electrode layers and positive electrode layers in secondary batteries can be used.
• the negative electrode layer and the positive electrode layer have a structure in which an electrode mixture layer is provided on a current collector.
• the electrode mixture layer may be formed on at least one surface of the current collector.
• the electrode mixture can contain, for example, an electrode active material and a binder composition.
• the electrode active material is not particularly limited.
• a conventionally known negative electrode active material (negative electrode active material) or positive electrode active material (positive electrode active material) can be used.
• Examples of the negative electrode active material include carbon materials such as artificial graphite, natural graphite, non-graphitizable carbon, graphitizable carbon, activated carbon, or phenol resin and pitch carbonized carbon; Cu, Li, Mg, B, Metal materials and alloy materials such as Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, Cd, Ag, Zn, Hf, Zr and Y; and GeO, GeO 2 , SnO, SnO 2 , PbO and Examples thereof include metal oxides such as PbO 2 .
• a lithium-based positive electrode active material containing at least lithium is preferable.
• the lithium-based positive active material for example, LiCoO 2, LiNi x Co 1 -x O 2 (0 ⁇ x ⁇ 1), the general formula Limy 2 (M such LiNiCoMnO 2 is, Co, Ni, Fe, Mn , Cr, At least one kind of transition metal such as V: Y is a chalcogen element such as O or S), a composite metal oxide having a spinel structure such as LiMn 2 O 4 , and an olivine type lithium such as LiFePO 4 Compounds and the like.
• cellulose compounds such as vinylidene fluoride polymer, polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylic acid, polyimide, carboxymethyl cellulose, ammonium salts and alkali metal salts of cellulose compounds, And those containing at least one of polyacrylonitrile (PAN) and the like.
• PTFE polytetrafluoroethylene
• SBR styrene butadiene rubber
• PAN polyacrylonitrile
• the electrode mixture is, for example, a conductive aid such as carbon black, acetylene black, ketjen black, graphite powder, carbon fiber, or carbon nanotube; a pigment dispersant such as polyvinylpyrrolidone; and an adhesive such as polyacrylic acid or polymethacrylic acid An auxiliary agent or the like may further be included.
• a conductive aid such as carbon black, acetylene black, ketjen black, graphite powder, carbon fiber, or carbon nanotube
• a pigment dispersant such as polyvinylpyrrolidone
• an adhesive such as polyacrylic acid or polymethacrylic acid
• An auxiliary agent or the like may further be included.
• the current collector is a base material for the negative electrode layer and the positive electrode layer, and is a terminal for taking out electricity.
• the material of the current collector is not particularly limited, and metal foil or metal steel such as aluminum, copper, iron, stainless steel, steel, nickel and titanium can be used.
• the thickness of the current collector is not particularly limited, but is preferably 5 to 100 ⁇ m, and more preferably 5 to 70 ⁇ m.
• the thickness of the electrode mixture layer is not particularly limited, but is usually 6 to 1000 ⁇ m, and preferably 7 to 500 ⁇ m.
• the fluororesin layer may be provided in contact with the separator in at least one of the negative electrode layer and the positive electrode layer, and in one example, it is preferably provided in the positive electrode layer.
• the coating composition according to this embodiment is applied to at least one surface of at least one of the negative electrode layer and the positive electrode layer.
• the electrolyte used for the secondary battery in the present embodiment is not particularly limited, and for example, a known electrolyte for the secondary battery can be used.
• the electrolyte include LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiSbF 6 , LiCF 3 SO 3 , Li (CF 3 SO 2 ) 2 N, LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ). 3 C, LiBPh 4 and the like.
• an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent can also be used.
• non-aqueous solvent examples include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and difluoroethylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and fluorine-substituted products thereof; and cyclic esters such as ⁇ -butyrolactone and ⁇ -valerolactone; and mixed solvents thereof.
• cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and difluoroethylene carbonate
• chain carbonates such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and fluorine-substituted products thereof
• cyclic esters such as ⁇ -butyrolactone and ⁇ -valerolactone
• the secondary battery according to the present embodiment is provided with a fluororesin layer formed from the coating composition according to the present embodiment.
• the separator is the separator described above.
• the electrode is the electrode described above.
• the secondary battery according to the present embodiment can be classified by, for example, the type of electrolyte. Specifically, for example, a nonaqueous electrolyte secondary battery, a solid electrolyte secondary battery, and the like can be given, and among them, a nonaqueous electrolyte secondary battery is preferable.
• nonaqueous electrolyte secondary battery examples include a polymer battery including a gel electrolyte.
• Other members in the nonaqueous electrolyte secondary battery are not particularly limited, and for example, conventionally used members can be used.
• Examples of the method for producing a non-aqueous electrolyte secondary battery include a method in which a negative electrode layer and a positive electrode layer are overlapped via a separator, put into a battery container, and an electrolyte is injected into the battery container to seal it.
• a part of the core-shell type particles (ideally only the shell part) contained in the coating composition is melted by hot pressing after injection of the electrolytic solution, and the electrode is formed by the formed fluororesin layer. And the separator adhere to each other.
• the temperature of the hot press is determined according to the melting temperature of the first polymer and the melting temperature of the core-shell type particles, and can be set to 30 to 150 ° C., for example.
• the pressure of the hot press is not particularly limited, but can be set to 1 to 30 MPa, for example.
• the melting temperature of the first polymer in the presence of the electrolytic solution is higher than the temperature of the hot press, it is reduced that the vinylidene fluoride particles in the core portion are crushed by the hot press. can do.
• the core-shell type particle includes a core part and a shell part surrounding the core part, and the core part is derived from vinylidene fluoride.
• the second polymer has a lower melting point than the first polymer.
• the melting point of the core-shell type particle is preferably 145 ° C. or higher.
• the first polymer contained in the core part and / or the second polymer contained in the shell part is derived from a halogenated alkyl vinyl compound.
• the halogenated alkyl vinyl compound is preferably contained in the core-shell type particle in an amount of 0.2 mol% or more and 5 mol% or less.
• the structural unit derived from the halogenated alkyl vinyl compound is a structural unit derived from the fluorinated alkyl vinyl compound, and the structural unit derived from the fluorinated alkyl vinyl compound. May be contained in the second polymer.
• the second polymer further includes at least one of a structural unit derived from an unsaturated dibasic acid and a structural unit derived from an unsaturated dibasic acid monoester. It is preferable to include.
• the constituent unit of the first polymer may be only a constituent unit derived from vinylidene fluoride.
• One embodiment of the present invention also provides a dispersion containing core-shell particles and a dispersion medium according to one embodiment of the present invention.
• One embodiment of the present invention is also a coating composition for forming a porous fluororesin layer provided on at least one surface of a separator provided between a negative electrode layer and a positive electrode layer in a secondary battery.
• a coating composition comprising core-shell particles according to an embodiment of the present invention is provided.
• the coating composition according to an embodiment of the present invention may further include a thickener.
• the coating composition according to an embodiment of the present invention may further include a filler.
• One embodiment of the present invention also provides a separator in which the coating composition according to one embodiment of the present invention is applied to at least one surface.
• One embodiment of the present invention is also a secondary battery provided with a fluororesin layer formed from the coating composition according to an embodiment of the present invention, wherein the fluororesin layer includes the negative electrode layer and the above-described negative electrode layer.
• a layer containing the second polymer formed by hot pressing the positive electrode layer and the separator, and the layer containing the second polymer includes the first polymer Provided is a secondary battery including particles containing the same.
• One embodiment of the present invention also provides fluorine provided on at least one surface of the negative electrode layer and the positive electrode layer so as to be in contact with a separator provided between the negative electrode layer and the positive electrode layer in the secondary battery.
• a coating composition for forming a resin layer is provided, the coating composition including core-shell type particles according to an embodiment of the present invention.
• a method for producing a core-shell type particle according to an embodiment of the present invention is a method for producing a core-shell type particle including a core part and a shell part surrounding the core part, and is derived from vinylidene fluoride
• fluoropolymer particles core-shell type particles and vinylidene fluoride particles (hereinafter collectively referred to as fluoropolymer particles) according to the present invention were prepared, and the physical properties of the fluoropolymer particles were measured. Moreover, the coating separator was manufactured using the said fluoropolymer particle, and the peeling strength test and the air permeability measurement test were done using it. Before describing specific examples, the calculation method of “solid content concentration” and “particle diameter” in this specification will be described below.
• Solid concentration About 5 g of a dispersion liquid (hereinafter also referred to as latex) containing fluoropolymer particles prepared by polymerization was placed in an aluminum cup, dried at 80 ° C. for 3 hours, and the weight was measured before and after drying to calculate the concentration.
• latex a dispersion liquid
• the particle diameter of the fluoropolymer particles was calculated by regularization analysis of the dynamic light scattering method. Specifically, “DelsaMaxCORE” manufactured by BECKMAN COULTER was used and measured according to JIS Z 8828, and the larger peak among the two large and small peaks obtained by regularization analysis was defined as the particle diameter.
• Example 1 Polymerization of core part: 280 parts by mass of ion-exchanged water was put in an autoclave, and deaeration was performed by nitrogen bubbling for 30 minutes. Next, 0.2 parts by mass of disodium hydrogen phosphate and 1.0 part by mass of ammonium perfluorooctanoate (PFOA) were charged and pressurized to 4.5 MPa to perform nitrogen substitution three times. 0.05 parts by mass of ethyl acetate and 35 parts by mass of vinylidene fluoride (VDF) were added all at once to the autoclave. After the temperature was raised to 80 ° C.
• PFOA ammonium perfluorooctanoate
• ammonium persulfate (APS) aqueous solution was added in an amount corresponding to 0.06 parts by mass in terms of APS to initiate polymerization.
• the internal pressure of the can was 4.3 MPa.
• VDF vasifier
• the polymerization was completed when the pressure dropped to 1.5 MPa to obtain a latex containing core part particles.
• the obtained latex had a solid content concentration of 24.0 wt% and a particle size of 140 nm.
• shell part 700 parts by mass of ion-exchanged water was put in an autoclave, and deaeration was performed by nitrogen bubbling for 30 minutes. Next, 100 parts by mass of water-dispersed core part particles and 0.5 part by mass of PFOA were charged and pressurized to 4.5 MPa to perform nitrogen substitution three times. 0.05 parts by mass of ethyl acetate, 90 parts by mass of vinylidene fluoride (VDF), and 10 parts by mass of hexafluoropropylene (HFP) were added to the autoclave. After raising the temperature to 80 ° C.
• VDF vinylidene fluoride
• HFP hexafluoropropylene
• a 5 wt% APS aqueous solution was added in an amount corresponding to 0.1 part by mass in terms of APS to initiate polymerization.
• the pressure inside the can at this time was 3.7 MPa. After the start of the reaction, when the pressure dropped to 1.5 MPa, the polymerization of the shell portion was completed, and a latex containing core-shell type particles was obtained.
• the resulting latex had a solid content concentration of 13.4 wt% and a particle size of 180 nm.
• Example 2 Polymerization of core part: Vinylidene fluoride particles of the core part were obtained in the same manner as in Example 1.
• Polymerization of shell part Polymerization was carried out in the same manner as in Example 1 except that VDF was changed from 90 parts by mass to 88 parts by mass and HFP was changed from 10 parts by mass to 12 parts by mass to obtain latex containing core-shell type particles.
• the resulting latex had a solid content concentration of 13.8 wt% and a particle size of 170 nm.
• Example 3 Polymerization of core part: Vinylidene fluoride particles of the core part were obtained in the same manner as in Example 1.
• Polymerization of shell part Polymerization was carried out in the same manner as in Example 1 except that VDF was changed from 90 parts by mass to 78 parts by mass and HFP was changed from 10 parts by mass to 22 parts by mass to obtain latex containing core-shell type particles.
• the resulting latex had a solid content concentration of 13.4 wt% and a particle size of 170 nm.
• Example 4 Polymerization of core part: Vinylidene fluoride particles of the core part were obtained in the same manner as in Example 1.
• Polymerization of shell part Polymerization was carried out in the same manner as in Example 1 except that VDF was changed from 90 parts by mass to 70 parts by mass and HFP was changed from 10 parts by mass to 30 parts by mass to obtain latex containing core-shell type particles.
• the obtained latex had a solid content concentration of 13.5 wt% and a particle size of 170 nm.
• Example 5 Polymerization of core part: Latex containing core part particles by polymerizing in the same manner as in Example 1 except that VDF added to the autoclave at once is changed from 35 parts by weight to 30 parts by weight and 5.0 parts by weight of HFP is further added. Got. The obtained latex had a solid content concentration of 21.3 wt% and a particle size of 130 nm.
• Polymerization of shell part Polymerization was carried out in the same manner as in Example 3 to obtain a latex containing core-shell type particles. The resulting latex had a solid content concentration of 13.5 wt% and a particle size of 160 nm.
• Example 6 Polymerization of core part: Vinylidene fluoride particles of the core part were obtained in the same manner as in Example 1. Polymerization of shell part: 700 parts by mass of ion-exchanged water was put in an autoclave, and deaeration was performed by nitrogen bubbling for 30 minutes. Next, 100 parts by mass of water-dispersed core part particles and 0.5 part by mass of PFOA were charged and pressurized to 4.5 MPa to perform nitrogen substitution three times. 0.05 parts by mass of ethyl acetate, 78 parts by mass of VDF, 22 parts by mass of HFP, and 0.1 parts by mass of monomethyl maleate (MMM) were added to the autoclave. After raising the temperature to 80 ° C.
• MMMM monomethyl maleate
• a 5 wt% APS aqueous solution was added in an amount corresponding to 0.1 part by mass in terms of APS to initiate polymerization.
• the pressure inside the can at this time was 3.4 MPa. After the start of the reaction, when the pressure dropped to 1.5 MPa, the polymerization of the shell portion was completed, and a latex containing core-shell type particles was obtained.
• the obtained latex had a solid content concentration of 13.3 wt% and a particle size of 170 nm.
• Example 1 A latex containing vinylidene fluoride particles was obtained by polymerizing in the same manner as in the core part of Example 1 except that ammonium perfluorooctanoate (PFOA) was changed from 1.0 part by mass to 0.6 parts by mass.
• PFOA ammonium perfluorooctanoate
• the obtained latex had a solid content concentration of 21.4 wt% and a particle size of 180 nm.
• Comparative Example 2 Polymerization was conducted in the same manner as in Comparative Example 1 except that vinylidene fluoride (VDF) added to the autoclave at once was changed from 35 parts by mass to 27 parts by mass, and further 8.0 parts by mass of hexafluoropropylene (HFP) was added. A latex containing vinylidene fluoride particles was obtained. The obtained latex had a solid content concentration of 21.4 wt% and a particle size of 190 nm.
• VDF vinylidene fluoride
• HFP hexafluoropropylene
• Example 4 Polymerization of core part: Example except that vinylidene fluoride (VDF) added to the autoclave at once is changed from 30 parts by mass to 25 parts by mass and hexafluoropropylene (HFP) is changed from 5.0 parts by mass to 10.0 parts by mass. Polymerization was conducted in the same manner as in Example 1 to obtain a latex containing vinylidene fluoride particles in the core. The obtained latex had a solid content concentration of 21.3 wt% and a particle size of 140 nm.
• Polymerization of shell part Polymerization was carried out in the same manner as in Example 3 to obtain a latex containing core-shell type particles. The resulting latex had a solid content concentration of 13.4 wt% and a particle size of 170 nm.
• the melting point of the fluoropolymer particles in the dispersion prepared by polymerization was measured in the form of a film.
• the film was produced by the following operation. Between two aluminum foils sprayed with a release agent, about 1 g of fluoropolymer particles pulverized by salting out with a 5 cm long ⁇ 5 cm wide ⁇ 150 ⁇ m thick mold was sandwiched and pressed at 200 ° C. The melting point was measured according to ASTM d 3418 using DSC (“DSC-1” manufactured by METTTLER).
• a 1760 is the absorbance derived from stretching vibration of the carbonyl group to be detected near 1760 cm -1, and the absorbance from the peak detected in the 1600 cm -1 ⁇ 1800 cm -1 in the stretching vibration of the carbonyl group did.
• a 3020 is the absorbance derived from stretching vibration of CH detected around 3020cm -1, a peak detected in the 2900 cm -1 ⁇ 3100 cm -1 and absorbance derived from stretching vibration of a carbonyl group.
• Fluoropolymer particle-coated separators were prepared using the fluoropolymer particles obtained in each Example and each Comparative Example, and a peel strength test with an electrode (positive electrode) was performed.
• the fluoropolymer particle coating separator and electrode manufacturing method will be described in detail below.
• LiNiCoMnO 2 manufactured by MX6 Umicore
• the conductive auxiliary agent manufactured by SuperPTIMCAL
• PVDF polyvinylidene fluoride
• KF # 7200 manufactured by Kureha was added to N- methyl-2-pyrrolidone slurry was applied to an Al foil (thickness: 15 ⁇ m). After drying, pressing was performed and heat treatment was performed at 120 ° C. for 3 hours to obtain a positive electrode having an electrode bulk density of 3.0 [g / cm 3 ] and a basis weight of 103 [g / m 2 ].
• a sample for measuring the peel strength of the counter positive electrode was obtained by hot pressing the Al laminate cell. Specifically, a sample for measuring the peel strength of the counter positive electrode was produced by performing hot pressing at 100 ° C. for 2 minutes after preheating for 1 minute at a surface pressure of about 4 MPa. In this sample for measuring the peel strength of the positive electrode, a fluororesin layer was formed at the interface between the fluoropolymer particle-coated separator and the electrode (positive electrode) by hot pressing.
• the positive electrode was fixed, and a 180 ° peel test was performed at a head speed of 200 mm / min using a tensile tester (“STA-1150 UNIVERSAL TESTING MACHINE” manufactured by ORIENTEC). The peel strength was measured.
• Fluoropolymer particle-coated separators were prepared using the fluoropolymer particles obtained in each Example and each Comparative Example. A fluororesin layer coating separator for measuring air permeability after hot pressing with the electrode (negative electrode) was prepared, and the air permeability was measured. The fluoropolymer particle coating separator and electrode manufacturing method will be described in detail below.
• the wire bar was prepared in the same manner as the coating separator prepared in the peel strength test, except that the wet coating amount was changed from 24 ⁇ m (count 12) to 12 ⁇ m (number 6).
• the separator and the negative electrode were peeled off, and the separator was washed to obtain a sample for measuring air permeability.
• a sample for air permeability measurement is hot-pressed at 100 ° C. for 1 minute at a surface pressure of about 3 MPa to form a fluororesin layer at the interface between the fluoropolymer particle-coated separator and the electrode (negative electrode). did.
• the separator is washed with dimethyl carbonate (DMC), and dried at 70 ° C. for 2 hours, thereby obtaining a sample for measuring air permeability.
• DMC dimethyl carbonate
• the air permeability was measured using a Gurley type densometer (manufactured by Toyo Seiki Seisakusho) in accordance with JISP 8117 and ISO 5636.
• the core-shell type particles according to the present invention can be suitably used, for example, in the production of secondary batteries.

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