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WO2013146126A1 - Lithium ion secondary battery separator with process film and manufacturing method for same - Google Patents

Lithium ion secondary battery separator with process film and manufacturing method for same Download PDF

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Publication number
WO2013146126A1
WO2013146126A1 PCT/JP2013/056027 JP2013056027W WO2013146126A1 WO 2013146126 A1 WO2013146126 A1 WO 2013146126A1 JP 2013056027 W JP2013056027 W JP 2013056027W WO 2013146126 A1 WO2013146126 A1 WO 2013146126A1
Authority
WO
WIPO (PCT)
Prior art keywords
process film
film
separator
lithium ion
ion secondary
Prior art date
Application number
PCT/JP2013/056027
Other languages
French (fr)
Japanese (ja)
Inventor
亘 森田
孝至 森岡
田矢　直紀
Original Assignee
リンテック株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by リンテック株式会社 filed Critical リンテック株式会社
Publication of WO2013146126A1 publication Critical patent/WO2013146126A1/en

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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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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 separator for a lithium ion secondary battery with a process film in which a porous film is formed on a process film and a method for producing the same.
  • Lithium ion secondary batteries are widely used as power sources for portable devices because of their high energy density. In recent years, with the reduction in size, weight, and performance of portable devices, there has been an increasing demand for higher performance and improved safety of lithium ion secondary batteries. Lithium ion secondary batteries are also spreading to large-size applications such as electric vehicles and household power storage systems.
  • a lithium ion secondary battery is configured by providing a separator between a positive electrode and a negative electrode.
  • a porous film of polyolefin resin formed by stretching is generally used.
  • the porous membrane of polyolefin-based resin shrinks when the inside of the battery becomes high temperature and there is a risk of short circuit, various improvements have been made in the past in order to prevent such short circuit.
  • Patent Document 1 discloses a separator in which a first porous layer mainly composed of a thermoplastic resin such as a polyolefin-based resin and a second porous layer mainly composed of fine particles are laminated. ing.
  • Patent Documents 2 and 3 disclose a method of forming a porous film using a polyimide resin or an aramid fiber nonwoven fabric.
  • these separators have a problem that the manufacturing method becomes complicated and the manufacturing cost increases due to an increase in the number of processes and the use of expensive materials.
  • a porous film is formed by applying a slurry for forming a porous film containing a binder and fine particles on a process film and drying the slurry.
  • a method of peeling a film from a process film is known (see, for example, Patent Documents 4 and 5).
  • a polyester film coated with silicone may be used to facilitate peeling of the porous membrane from the process film.
  • a porous film composed of a predetermined binder and fine particles is not sufficiently peelable with respect to a normal silicone release agent. For this reason, even if a normal silicone coat film is used as the process film, the porous film cannot be peeled off from the process film satisfactorily, and problems such as breakage of the porous film during peeling may occur.
  • high-speed peeling is required for industrialization, but when the porous film is peeled from the process film at high speed, the peeling performance tends to deteriorate, and the porous film is damaged, so the performance as a lithium ion battery separator. Is likely to drop, and short circuits are likely to occur.
  • the porous membrane has a problem in that when the slurry for forming a porous membrane is dried on the process film, the film shrinks with the process film and curls. Furthermore, when the porous membrane is thin, the above-mentioned curling and breakage at the time of peeling are likely to occur. For this reason, when a normal silicone coat film is used as the process film, it may be difficult to reduce the thickness of the porous membrane. Especially in applications where high durability and electrical insulation are required, it may be desirable to use a fluororesin binder as the binder, but the porous film using a fluororesin binder is likely to curl. It was difficult to reduce the thickness of the porous film.
  • This invention is made
  • the subject of this invention is able to peel without damaging a porous membrane from a process film, and suppresses the curl which generate
  • the present inventors set the elastic modulus of the cured layer of the silicone resin composition of the process film and the bending resistance of the process film to a predetermined value. It has been found that it is possible to prevent breakage when the porous film is peeled off from the process film, and that the separator for a lithium ion secondary battery with a process film having a porous film of a resin binder is less likely to be curled. It was. That is, the present invention provides the following (1) to (12).
  • a lithium ion secondary battery comprising a process film having a cured layer of a silicone resin composition, and a porous film provided on the cured layer and containing fine particles (A) and a resin binder (B)
  • a separator The separator for lithium ion secondary batteries with a process film whose elastic modulus of the said hardened layer is 0.15 GPa or more, and the bending resistance of the said process film by the Gurley method is 0.3 mN or more.
  • the porous film was formed by applying a porous film forming composition containing fine particles (A), a resin binder (B) and a solvent (C) on the cured layer and drying.
  • the separator for lithium ion secondary batteries with a process film as described in said (1) which is what.
  • a porous film-forming composition containing fine particles (A) and a resin binder (B) is applied onto the cured layer of a process film having a cured layer of a silicone resin composition, and dried. It is a manufacturing method of the separator for lithium ion secondary batteries with a process film which obtains the separator for lithium ion secondary batteries with a process film, Comprising: The elastic modulus of the said hardened layer is 0.15 GPa or more, and the Gurley method of the said process film The manufacturing method of the separator for lithium ion secondary batteries with a process film whose bending resistance by 0.3 is 0.3 mN or more.
  • a separator for a lithium ion secondary battery with a process film that prevents curling that occurs during the formation of the porous film and breakage of the porous film that occurs when the porous film is peeled from the process film can be provided.
  • the separator with a process film of the present invention includes a base film, a process film having a cured layer of a silicone resin composition provided on one surface of the base film, and a fine film provided on the cured layer.
  • A the separator for lithium ion secondary batteries which consists of a porous film containing a resin binder (B).
  • the fine particles (A) can be used without particular limitation as long as they have heat resistance and electrical insulation and are chemically and electrochemically stable.
  • heat resistance means that substantial dimensional change and chemical composition change due to softening or the like do not occur at least at 150 ° C.
  • chemically stable means that there is no change in form in the electrolytic solution and no change in composition due to a chemical reaction.
  • electrochemically stable means that a side reaction due to an electrochemical redox reaction does not occur in a lithium ion secondary battery.
  • the fine particles (A) are not particularly limited, and examples thereof include boehmite, silica, titanium oxide, magnesium oxide, and alumina. Preferably, boehmite is used.
  • the fine particles (A) may be modified for the purpose of improving electrical insulation and dispersibility in a solvent. These fine particles may be used alone or in combination of two or more.
  • the size of the fine particles (A) is desirably an average particle size of 0.1 ⁇ m or more and 5 ⁇ m or less.
  • the average particle size is 0.1 ⁇ m or more, the pore size of the porous membrane becomes an appropriate size, the ionic conductivity in the porous membrane is improved, and the battery characteristics of the lithium ion secondary battery can be improved. .
  • the average particle diameter is 5 ⁇ m or less, the pore diameter of the porous film is prevented from becoming too large, and short-circuiting due to lithium dendride hardly occurs.
  • the average particle size of the fine particles (A) is the number average particle size measured with a laser diffraction particle size distribution meter.
  • the resin binder (B) may be any resin that has heat resistance and electrical insulation, is chemically and electrochemically stable, and can favorably adhere the fine particles (A).
  • the resin binder (B) is not particularly limited, and various types can be used.
  • polyester resins such as ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, urethane resins, epoxy resins, and polyethylene terephthalate.
  • the resin binder (B) is preferably a fluorine-based resin such as polyfluorinated fluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, or polyvinyl fluoride, and more preferably polyvinylidene fluoride.
  • a fluorine-based resin such as polyfluorinated fluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, or polyvinyl fluoride, and more preferably polyvinylidene fluoride.
  • high durability and electrical insulation can be imparted to the porous membrane by using a fluororesin.
  • the porous membrane is likely to curl and more easily damaged when peeled off from the process film. Damage can be prevented appropriately.
  • the molecular weight of the resin binder (B) is preferably a weight average molecular weight of 100,000 to 2,000,000, more preferably 500,000 to 1,500,000.
  • the weight average molecular weight is a standard polystyrene equivalent value measured by gel permeation chromatography (GPC).
  • the fine particles (A) in the porous film are preferably 40% by volume or more and 85% by volume or less, more preferably 60% by volume or more and 80% by volume or less.
  • the porous film within the volume ratio range has a good peeling force with respect to the cured layer of the process film.
  • the volume ratio to the above lower limit or more, the porosity of the porous membrane becomes appropriate, and the ionic conductivity in the porous membrane is improved, and the battery characteristics of the lithium ion secondary battery are good. Can be.
  • the volume ratio of the resin binder (B) can be set to a predetermined value or more, and the strength of the porous film can be kept good.
  • the thickness of the porous membrane is not particularly limited, but is preferably 10 ⁇ m or more and 30 ⁇ m or less. By setting the film thickness to 10 ⁇ m or more, the strength of the porous film can be made sufficient. In addition, by setting the film thickness to 30 ⁇ m or less, the ion conduction path can be set to an appropriate length, and the battery characteristics of the lithium ion secondary battery can be improved.
  • the porosity of the porous membrane is not particularly limited, but is preferably 30% or more and 80% or less. By setting the porosity to 30% or more, it is possible to prevent the ionic conductivity from decreasing. Moreover, it can prevent that the intensity
  • the cured layer of the silicone resin composition may be any material that is stable with respect to the composition for forming a porous film and can appropriately peel the porous film.
  • “stable with respect to the composition for forming a porous film” means that the composition for forming a porous film undergoes a morphological change or a chemical reaction during the production process of the porous film. It means that no change occurs.
  • the silicone resin composition is not particularly limited as long as the cured layer can have a predetermined elastic modulus as described later, and various types can be used. Examples thereof include, but are not limited to, an addition reaction type silicone resin, a crosslinking agent, and an addition reaction type silicone resin composition containing a catalyst. Further, if desired, a photosensitizer, an addition reaction inhibitor, a release adjusting agent such as silicone gum or silicone varnish, and an adhesion improving agent may be added.
  • addition reaction type silicone resin there is no restriction
  • the crosslinking agent is for curing the silicone resin composition, and examples thereof include polyorganosiloxane having at least two functional groups having hydrogen atoms bonded to silicon atoms in one molecule.
  • the amount of the crosslinking agent used is preferably 0.3 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the addition reaction type silicone resin.
  • the catalyst a platinum-based catalyst is usually used.
  • platinum-based catalyst examples include particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, rhodium catalyst, and the like.
  • the usage-amount of a catalyst is about 1 mass ppm or more and about 1000 mass ppm or less as a platinum-type metal in the total amount of an addition reaction type silicone resin and a crosslinking agent.
  • a photosensitizer there is no restriction
  • the addition reaction inhibitor is a component used for imparting storage stability of the silicone resin composition at room temperature.
  • the thickness of the cured layer of the silicone resin composition is not particularly limited, but is preferably 40 nm or more and 300 nm or less.
  • the film thickness is preferably 40 nm or more and 300 nm or less.
  • the cured layer of the silicone resin composition in the process film has an elastic modulus of 0.15 GPa or more.
  • the elastic modulus is preferably 0.20 GPa or more, more preferably 0.25 GPa or more.
  • the resin binder in the porous film forming composition soaks into the cured layer of the silicone resin composition, and the process film has sufficient releasability from the porous film. There is a possibility that it cannot be done.
  • the elastic modulus is 0.25 GPa or more, the peeling performance is further improved, and the peeling performance at the time of high-speed peeling can be particularly improved.
  • the elastic modulus of the cured layer of the silicone resin composition is not particularly limited, but is generally about 1.0 GPa or less, preferably 0.5 GPa or less for a polyorganosiloxane having a functional group from the viewpoint of composition.
  • the elastic modulus of the cured layer can be measured by a known method, but in the present specification, it is an elastic modulus measured by a nanoindenter from the surface of the cured layer, and the method described in the examples. Can be sought.
  • a base film that does not undergo substantial dimensional change or chemical composition change due to softening or the like with respect to a predetermined drying temperature is used.
  • a base film There is no restriction
  • the thickness of the base film is not particularly limited as long as a predetermined bending resistance can be obtained as will be described later, but is, for example, 50 ⁇ m or more and 150 ⁇ m or less, preferably 60 ⁇ m or more and 120 ⁇ m or less. If the thickness of the base film is within the above range, a predetermined bending resistance described later can be easily obtained.
  • the releasability on the cured layer side of the process film is such that the porous film does not peel from the process film in the slit process or winding process after the porous film is formed, and the porous film is peeled off from the process film.
  • the peeling step it is sufficient that the porous film does not change its shape or breakage occurs.
  • the peeling force when peeling the porous membrane from the process film at a peeling speed of 0.3 m / min and 10 m / min at a peeling angle of 180 ° is 10 mN / 50 mm or more and 400 mN at each peeling speed.
  • the peeling force By setting the peeling force to the above lower limit or more, it is possible to prevent the porous film from being lifted off from the process film and being peeled off when the slit process or the winding process after the porous film formation is not intended. . Moreover, by setting it as the said upper limit or less, when peeling a porous film from a process film, it can prevent that a shape change arises in a porous film, or a damage arises.
  • the arithmetic average roughness of the cured layer surface of the process film is preferably 15.0 nm or less.
  • the porous film formed on the cured layer of the process film is prevented from biting into the cured layer, and a shape change occurs when the porous film is peeled off. It is prevented that damage occurs.
  • the maximum cross-sectional height of the hardened layer surface of a process film is 200.0 nm or less.
  • the porous film formed on the cured layer of the process film is prevented from biting into the cured layer, and a shape change occurs when the porous film is peeled off. It is prevented that damage occurs.
  • the process film of the present invention has a bending resistance by the Gurley method of 0.3 mN or more.
  • the porous film is formed by applying and drying the porous film-forming composition on the process film. In this drying process, the porous film tends to undergo heat shrinkage. However, if the bending resistance is less than 0.3 mN, the process film cannot sufficiently resist the heat shrinkage. A big curl will arise in a separator with a film.
  • the process film having the bending resistance is sufficiently resistant to the heat shrinkage of the porous film, and the bending resistance is 0.5 mN or more so that curling can be more effectively suppressed. It is preferable, and it is more preferable that it is 0.75 mN or more.
  • the bending resistance is preferably 4.0 mN or less, and more preferably 2.0 mN or less so that the separator with a process film to be obtained can be wound into a roll.
  • the bending resistance by the Gurley method means a value measured in accordance with the JIS L-1096 A method (Gurley method).
  • a porous film-forming composition containing fine particles (A) and a resin binder (B) is applied onto a cured layer of a process film by a known method, It can be produced by drying at a temperature. At this time, the drying temperature is 120 to 180 ° C., and the drying time is, for example, 60 to 300 seconds.
  • the application method is not particularly limited, and examples thereof include dip coating, die coating, bar coating, and doctor blade.
  • the composition for forming a porous film contains the solvent (C) in addition to the fine particles (A) and the resin binder (B), and the fine particles (A) are dispersed in the solvent (C) to disperse the resin binder (B). Alternatively, it is dissolved.
  • the solvent (C) is not particularly limited as long as it can uniformly disperse the fine particles (A) and can uniformly disperse or dissolve the resin binder (B), and various solvents can be used.
  • N-methylpyrrolidone dimethylacetamide, dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, triethyl phosphate, methyl ethyl ketone, methyl isobutyl ketone and the like can be mentioned, and N-methylpyrrolidone (NMP) is preferably used.
  • the cured layer of the process film preferably has a contact angle with respect to the solvent (C) used for forming the porous film of 55 ° or more and 75 ° or less.
  • C solvent
  • the cured layer of the process film preferably has a contact angle with respect to the solvent (C) used for forming the porous film of 55 ° or more and 75 ° or less.
  • the solid content concentration of the composition for forming a porous film is not particularly limited, but is preferably 20% by mass or more and 60% by mass or less. By setting the solid content concentration within the above range, the viscosity of the composition for forming a porous film becomes an appropriate value, and a necessary coating amount for obtaining a predetermined film thickness can be obtained.
  • the composition can be applied uniformly.
  • the separator with a process film manufactured as described above is slit as necessary so as to have an appropriate width and length, and then wound into a roll.
  • the method of obtaining a laminated electrode body used for a lithium ion secondary battery by laminating a positive electrode and a negative electrode on a porous film using the separator with a process film of the present invention is not particularly limited. A method is mentioned.
  • the separator with a roll-formed process film is unwound and the process film is wound on a take-up roll to peel the porous film from the process film, and the positive electrode and the negative electrode are laminated on the peeled porous film. To do. At this time, the positive electrode and the negative electrode may or may not be unwound from the roll.
  • the elastic modulus of the cured layer of the silicone resin composition is set to 0.15 GPa or more and the bending resistance of the process film is set to 0.3 mN or more to curl the separator with the process film. Can be prevented, and furthermore, damage to the porous membrane that occurs when the porous membrane is peeled from the process film can be prevented.
  • the porous film of the present invention is less likely to be damaged or curled, and thus has excellent handleability and is easily thinned.
  • the measuring method of each physical property in the present invention is as follows.
  • (1) Elastic modulus of cured layer The process film having a cured layer of the silicone resin composition was allowed to stand for 24 hours under conditions of a temperature of 23 ° C and a relative humidity of 50%, and then the elastic modulus of the cured layer was measured. At this time, the process film was fixed on a glass plate using Bond Quick 5 manufactured by Konishi Co., Ltd., and measured at a temperature of 23 ° C. and a relative humidity of 50% using NanoInstant SA2 manufactured by NTS from the surface of the cured layer. went.
  • the elastic modulus of the cured layer was calculated as an average value of 20 points measured within a depth range of 5 to 10 nm from the surface of the cured layer.
  • (3) Contact angle of cured layer of process film to solvent (NMP) A process film having a cured layer of the silicone resin composition is allowed to stand for 24 hours at a temperature of 23 ° C. and a relative humidity of 50%. The contact angle was measured. The measurement was performed using DSA100S manufactured by KRUSS.
  • CD direction means the direction orthogonal to the flow direction of the manufacturing line of a process film and a separator with a process film.
  • Average particle size The number average particle size of the fine particles (A) was calculated by laser diffraction particle size distribution measurement. For the measurement, LA-920 manufactured by Horiba Ltd. was used. The number average particle diameter is calculated from the refractive index of the solvent and the fine particles (A) after the fine particles (A) are dispersed in water and diluted so that the transmittance at 532 nm is 70 to 90%.
  • the resin binder (B) was dissolved in tetrahydrofuran and measured at a temperature of 40 ° C. using gel permeation chromatography (GPC) to calculate a standard polystyrene equivalent value.
  • GPC gel permeation chromatography
  • HLC-8020 manufactured by Tosoh Corporation was used, and TSKguardcolumnHXL-H, TSKgelGMHXL ( ⁇ 2), and TSKgelG2000HXL, which are GPC columns manufactured by Tosoh Corporation, were passed in order.
  • Example 1 The fine particles (A) have a density of 2.96 g / cm 3 , boehmite fine particles having an average particle diameter of 0.2 ⁇ m, and the resin binder (B) has a density of 1.78 g / cm 3 and a weight average molecular weight of 1,000,000 polyfluorination. Vinylidene is blended so that the fine particles (A) in the total solids are 70% by volume, and N-methylpyrrolidone as the solvent (C) is put in a container so that the total solids concentration is 30% by mass. By stirring with a mechanical stirrer for 2 hours, a uniformly dispersed slurry-like composition for forming a porous film was prepared.
  • a 75 ⁇ m-thick polyethylene terephthalate film which is a base film
  • a cured layer of a process film (trade name “PDS752160”, manufactured by Lintec Corporation) having a cured layer of a silicone resin composition
  • the porous film-forming composition was uniformly applied using a comma coater so that the film thickness after drying was 20 ⁇ m, and dried at 150 ° C. for 150 seconds to produce a separator with a process film.
  • Example 2 The point which used the process film (The product name "PDS1002160” by Lintec Corporation) which has the hardened layer of a silicone resin composition on one surface of the polyethylene terephthalate film of thickness 100 micrometers which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
  • Example 3 Other than the use of a process film (trade name “PLD752060”, manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 75 ⁇ m-thick polyethylene terephthalate film, which is a base film, as the process film Produced a separator with a process film in the same manner as in Example 1.
  • a process film trade name “PLD752060”, manufactured by Lintec Corporation
  • Example 4 Other than the use of a process film having a cured layer of a silicone resin composition on one surface of a 100 ⁇ m-thick polyethylene terephthalate film as a process film (product name “PLD1002060” manufactured by Lintec Corporation) as the process film Produced a separator with a process film in the same manner as in Example 1.
  • a process film having a cured layer of a silicone resin composition on one surface of a 100 ⁇ m-thick polyethylene terephthalate film product name “PLD1002060” manufactured by Lintec Corporation
  • Example 5 The point which used the process film (the product name "PLS75T161" by Lintec Co., Ltd.) which has the hardened layer of a silicone resin composition on one surface of the 75-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
  • Example 6 The point which used the process film (the product name "PLS100T161" by Lintec Co., Ltd.) which has the hardened layer of a silicone resin composition on one surface of the 100-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
  • Comparative Example 1 The point which used the process film (the product name "PDS382160” by the Lintec Co., Ltd. product) which has the hardened layer of a silicone resin composition on one surface of the 38-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
  • Comparative Example 2 The point which used the process film (the product name "PDS252160” by Lintec Corporation) which has the hardened layer of a silicone resin composition on one surface of the 25-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
  • Comparative Example 5 As a process film, a process film (trade name “NF SP-PET 381031” manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 38 ⁇ m-thick polyethylene terephthalate film as a base film is used. A separator with a process film was produced in the same manner as in Example 1 except for the points used.
  • NF SP-PET 381031 manufactured by Lintec Corporation
  • Comparative Example 6 As a process film, a process film (trade name “NF SP-PET 251031” manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 25 ⁇ m-thick polyethylene terephthalate film as a base film is used. A separator with a process film was produced in the same manner as in Example 1 except for the points used.
  • NF SP-PET 251031 manufactured by Lintec Corporation
  • Comparative Example 7 As a process film, a process film having a cured layer of a silicone resin composition on one side of a 38 ⁇ m-thick polyethylene terephthalate film as a base film (product name “NF SP-PET38T103-1”, manufactured by Lintec Corporation) ) was used in the same manner as in Example 1 except that a separator with a process film was produced.
  • Comparative Example 8 As a process film, a process film having a cured layer of an alkyd resin composition on one surface of a 50 ⁇ m thick polyethylene terephthalate film as a base film (trade name “SP-PFS50AL-5”, manufactured by Lintec Corporation) A separator with a process film was produced in the same manner as in Example 1 except that was used.
  • Comparative Example 9 Separator with process film as in Example 1 except that a polyethylene terephthalate film (trade name “PET38T-100”, manufactured by Mitsubishi Plastics, Inc.) having a thickness of 38 ⁇ m without a cured layer was used as the process film. Manufactured.
  • a polyethylene terephthalate film (trade name “PET38T-100”, manufactured by Mitsubishi Plastics, Inc.) having a thickness of 38 ⁇ m without a cured layer was used as the process film.
  • the separators with process films according to Examples 1 to 4 were peeled off from the process film because the cured layer had a good elastic modulus and the process film had a suitable bending resistance.
  • the porous film was not changed in shape or damaged, and the amount of curling generated in the separator with the process film could be suppressed.
  • the elastic modulus of the cured layer was slightly low and the releasability at high speed of the process film was not good, the releasability at low speed was good and the porous film was damaged. The film could be peeled without changing its shape, and the amount of curling could be suppressed because of its good bending resistance.
  • the separators with a process film according to Comparative Examples 1 to 9 had poor curling softness of the process film, so that a large curl was generated in the porous film, and the performance was inferior to those of Examples 1 to 6.
  • Comparative Examples 5 to 9 since the elastic modulus of the cured layer was low or the cured silicone layer was not provided, the releasability was poor, and the porous film was damaged during peeling.

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Abstract

This lithium ion secondary battery separator with a process film is provided with a process film having a cured layer of a silicone resin composition and a porous film that is provided on the cured layer and contains fine particles (A) and a resin binder (B). The modulus of elasticity of the cured layer is 0.15 GPa or greater, and the bending resistance as measured by the Gurley method is 0.3 mN or greater.

Description

工程フィルム付きリチウムイオン二次電池用セパレータ、及びその製造方法Separator for lithium ion secondary battery with process film and method for producing the same
　本発明は、多孔質膜が工程フィルム上に形成されてなる工程フィルム付きリチウムイオン二次電池用セパレータおよびその製造方法に関する。 The present invention relates to a separator for a lithium ion secondary battery with a process film in which a porous film is formed on a process film and a method for producing the same.
　リチウムイオン二次電池は、エネルギー密度が高いという特徴から携帯機器の電源として広く用いられている。近年、携帯機器の小型化・軽量化および高性能化に伴い、リチウムイオン二次電池の高性能化および安全性向上の要請が高まっている。また、リチウムイオン二次電池は、電気自動車や家庭用蓄電システムなど大型サイズでの用途へも広がりを見せている。 Lithium ion secondary batteries are widely used as power sources for portable devices because of their high energy density. In recent years, with the reduction in size, weight, and performance of portable devices, there has been an increasing demand for higher performance and improved safety of lithium ion secondary batteries. Lithium ion secondary batteries are also spreading to large-size applications such as electric vehicles and household power storage systems.
　リチウムイオン二次電池は、正極と負極の間にセパレータが設けられて構成される。セパレータとしては、延伸により形成されたポリオレフィン系樹脂の多孔質膜が一般的に使用されている。しかし、ポリオレフィン系樹脂の多孔質膜は、電池内が高温になった際に収縮を起こし、短絡のおそれがあるので、そのような短絡を防止するために、従来種々の改良がなされている。
　例えば、特許文献１には、ポリオレフィン系樹脂等の熱可塑性樹脂を主成分とする第１の多孔質層と、微粒子を主体とした第２の多孔質層とを積層してなるセパレータが開示されている。また、特許文献２、３には、多孔質膜をポリイミド樹脂や、アラミド繊維不織布を用いて形成する方法が開示されている。
　しかし、これらセパレータでは、工程の増加や高価な材料の使用により、製造方法が複雑になり、また製造コストが高くなるという問題がある。 A lithium ion secondary battery is configured by providing a separator between a positive electrode and a negative electrode. As the separator, a porous film of polyolefin resin formed by stretching is generally used. However, since the porous membrane of polyolefin-based resin shrinks when the inside of the battery becomes high temperature and there is a risk of short circuit, various improvements have been made in the past in order to prevent such short circuit.
For example, Patent Document 1 discloses a separator in which a first porous layer mainly composed of a thermoplastic resin such as a polyolefin-based resin and a second porous layer mainly composed of fine particles are laminated. ing. Patent Documents 2 and 3 disclose a method of forming a porous film using a polyimide resin or an aramid fiber nonwoven fabric.
However, these separators have a problem that the manufacturing method becomes complicated and the manufacturing cost increases due to an increase in the number of processes and the use of expensive materials.
　一方で、工程を簡略化して安価に多孔質膜を得る方法として、工程フィルム上に、バインダと微粒子とを含む多孔質膜形成用スラリーを塗布して、そのスラリーを乾燥させて形成した多孔質膜を工程フィルムから剥離する方法が知られている（例えば、特許文献４、５参照）。工程フィルムには、多孔質膜を工程フィルムから剥離しやすくするために、シリコーンコートしたポリエステルフィルムが使用されることがある。 On the other hand, as a method for obtaining a porous film at a low cost by simplifying the process, a porous film is formed by applying a slurry for forming a porous film containing a binder and fine particles on a process film and drying the slurry. A method of peeling a film from a process film is known (see, for example, Patent Documents 4 and 5). For the process film, a polyester film coated with silicone may be used to facilitate peeling of the porous membrane from the process film.
特開２００６－３２３５９号公報JP 2006-32359 A 特開２０００－３０６５６８号公報JP 2000-306568 A 特開２０１２－９１６５号公報JP 2012-9165 A 特開２００５－２７６５０３号公報JP 2005-276503 A 特開２００８－２７８３９号公報JP 2008-27839 A
　しかし、本発明者らの検討によると、所定のバインダと微粒子とから構成される多孔質膜は、通常のシリコーン剥離剤に対する剥離性が十分ではない。そのため、工程フィルムとして通常のシリコーンコートフィルムを使用しても、多孔質膜を工程フィルムから良好に剥離できず、剥離時に多孔質膜が破損する等の不具合が生じることがある。特に、工業化には高速剥離が必要とされるが、多孔質膜を工程フィルムから高速剥離する際、剥離性能が悪くなりやすく、多孔質膜が破損することによって、リチウムイオン電池用セパレータとしての性能が低下しやすく、短絡などが起こりやすい。 However, according to the study by the present inventors, a porous film composed of a predetermined binder and fine particles is not sufficiently peelable with respect to a normal silicone release agent. For this reason, even if a normal silicone coat film is used as the process film, the porous film cannot be peeled off from the process film satisfactorily, and problems such as breakage of the porous film during peeling may occur. In particular, high-speed peeling is required for industrialization, but when the porous film is peeled from the process film at high speed, the peeling performance tends to deteriorate, and the porous film is damaged, so the performance as a lithium ion battery separator. Is likely to drop, and short circuits are likely to occur.
　また、多孔質膜は、多孔質膜形成用スラリーを工程フィルム上で乾燥する際に工程フィルムとともに熱収縮して、カールが発生するという問題がある。さらに、多孔質膜が薄い場合、上記したカールや剥離時の破損が発生しやすく、そのため、工程フィルムとして通常のシリコーンコートフィルムを用いた場合、多孔質膜を薄膜化しにくいことがある。
　特に、高い耐久性や電気絶縁性が要求される用途では、バインダとしてフッ素系樹脂バインダを使用することが望まれることがあるが、フッ素樹脂バインダを使用した多孔質膜は、カールが発生しやすく、多孔質膜を薄膜化することは難しかった。 In addition, the porous membrane has a problem in that when the slurry for forming a porous membrane is dried on the process film, the film shrinks with the process film and curls. Furthermore, when the porous membrane is thin, the above-mentioned curling and breakage at the time of peeling are likely to occur. For this reason, when a normal silicone coat film is used as the process film, it may be difficult to reduce the thickness of the porous membrane.
Especially in applications where high durability and electrical insulation are required, it may be desirable to use a fluororesin binder as the binder, but the porous film using a fluororesin binder is likely to curl. It was difficult to reduce the thickness of the porous film.
　本発明は上記事情に鑑みてなされたものであり、本発明の課題は、多孔質膜を工程フィルムから破損させることなく剥離することができ、かつ多孔質膜乾燥時等に発生するカールを抑制し得る工程フィルム付きリチウムイオン二次電池用セパレータを提供することである。 This invention is made | formed in view of the said situation, The subject of this invention is able to peel without damaging a porous membrane from a process film, and suppresses the curl which generate | occur | produces at the time of porous membrane drying etc. It is providing the separator for lithium ion secondary batteries with a process film which can be performed.
　本発明者らは、上記課題を解決すべく鋭意検討を重ねた結果、工程フィルムのシリコーン樹脂組成物の硬化層の弾性率や、工程フィルムの剛軟度を所定の値に設定することにより、多孔質膜を工程フィルムから剥離する際の破断が防止できるとともに、樹脂バインダの多孔質膜を有する工程フィルム付きリチウムイオン二次電池用セパレータにカールが発生しにくくなることを見出し、本発明に至った。
　すなわち、本発明は、以下の（１）～（１２）を提供するものである。
（１）シリコーン樹脂組成物の硬化層を有する工程フィルムと、前記硬化層の上に設けられ、かつ微粒子（Ａ）及び樹脂バインダ（Ｂ）を含有する多孔質膜からなるリチウムイオン二次電池用セパレータとを備え、
　前記硬化層の弾性率が０．１５ＧＰａ以上であり、かつ前記工程フィルムのガーレ法による剛軟度が０．３ｍＮ以上である工程フィルム付きリチウムイオン二次電池用セパレータ。
（２）前記多孔質膜が、微粒子（Ａ）、樹脂バインダ（Ｂ）及び溶媒（Ｃ）を含有する多孔質膜形成用組成物を、前記硬化層上に塗布し、乾燥することにより形成したものである上記（１）に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（３）前記工程フィルムの硬化層の前記溶媒（Ｃ）に対する接触角が５５°以上７５°以下である上記（２）に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（４）前記工程フィルムの硬化層表面の算術平均粗さが１５．０ｎｍ以下である上記（１）～（３）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（５）前記工程フィルムの硬化層表面の最大断面高さが、２００．０ｎｍ以下である上記（１）～（４）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（６）微粒子（Ａ）がベーマイトである上記（１）～（５）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（７）微粒子（Ａ）の平均粒径が０．１μｍ以上５μｍ以下である上記（１）～（６）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（８）バインダ（Ｂ）の重量平均分子量が１００，０００以上２，０００，０００以下である上記（１）～（７）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（９）多孔質膜中の微粒子（Ａ）が４０体積％以上８５体積％以下である上記（１）～（８）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（１０）樹脂バインダ（Ｂ）が、フッ素系樹脂バインダである上記（１）～（９）のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（１１）前記フッ素系樹脂バインダが、ポリフッ化ビニリデンである上記（１０）に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。
（１２）微粒子（Ａ）と、樹脂バインダ（Ｂ）とを含有する多孔質膜形成用組成物を、シリコーン樹脂組成物の硬化層を有する工程フィルムの前記硬化層上に塗布し、乾燥して工程フィルム付きリチウムイオン二次電池用セパレータを得る工程フィルム付きリチウムイオン二次電池用セパレータの製造方法であって、前記硬化層の弾性率が０．１５ＧＰａ以上であり、かつ前記工程フィルムのガーレ法による剛軟度が０．３ｍＮ以上である工程フィルム付きリチウムイオン二次電池用セパレータの製造方法。 As a result of intensive studies to solve the above-mentioned problems, the present inventors set the elastic modulus of the cured layer of the silicone resin composition of the process film and the bending resistance of the process film to a predetermined value. It has been found that it is possible to prevent breakage when the porous film is peeled off from the process film, and that the separator for a lithium ion secondary battery with a process film having a porous film of a resin binder is less likely to be curled. It was.
That is, the present invention provides the following (1) to (12).
(1) For a lithium ion secondary battery comprising a process film having a cured layer of a silicone resin composition, and a porous film provided on the cured layer and containing fine particles (A) and a resin binder (B) A separator,
The separator for lithium ion secondary batteries with a process film whose elastic modulus of the said hardened layer is 0.15 GPa or more, and the bending resistance of the said process film by the Gurley method is 0.3 mN or more.
(2) The porous film was formed by applying a porous film forming composition containing fine particles (A), a resin binder (B) and a solvent (C) on the cured layer and drying. The separator for lithium ion secondary batteries with a process film as described in said (1) which is what.
(3) The separator for lithium ion secondary batteries with a process film as described in said (2) whose contact angle with respect to the said solvent (C) of the cured layer of the said process film is 55 degrees or more and 75 degrees or less.
(4) The separator for a lithium ion secondary battery with a process film according to any one of (1) to (3), wherein the arithmetic average roughness of the cured layer surface of the process film is 15.0 nm or less.
(5) The separator for a lithium ion secondary battery with a process film according to any one of the above (1) to (4), wherein the maximum cross-sectional height of the cured layer surface of the process film is 200.0 nm or less.
(6) The separator for a lithium ion secondary battery with a process film according to any one of (1) to (5), wherein the fine particles (A) are boehmite.
(7) The separator for a lithium ion secondary battery with a process film according to any one of the above (1) to (6), wherein the average particle diameter of the fine particles (A) is 0.1 μm or more and 5 μm or less.
(8) The separator for a lithium ion secondary battery with a process film according to any one of (1) to (7), wherein the binder (B) has a weight average molecular weight of 100,000 or more and 2,000,000 or less.
(9) The separator for a lithium ion secondary battery with a process film according to any one of the above (1) to (8), wherein the fine particles (A) in the porous film are 40% by volume or more and 85% by volume or less.
(10) The separator for a lithium ion secondary battery with a process film according to any one of the above (1) to (9), wherein the resin binder (B) is a fluororesin binder.
(11) The separator for a lithium ion secondary battery with a process film according to (10), wherein the fluororesin binder is polyvinylidene fluoride.
(12) A porous film-forming composition containing fine particles (A) and a resin binder (B) is applied onto the cured layer of a process film having a cured layer of a silicone resin composition, and dried. It is a manufacturing method of the separator for lithium ion secondary batteries with a process film which obtains the separator for lithium ion secondary batteries with a process film, Comprising: The elastic modulus of the said hardened layer is 0.15 GPa or more, and the Gurley method of the said process film The manufacturing method of the separator for lithium ion secondary batteries with a process film whose bending resistance by 0.3 is 0.3 mN or more.
　本発明では、多孔質膜形成時に発生するカールや、多孔質膜を工程フィルムから剥離する際に生じる多孔質膜の破損を防止する工程フィルム付きリチウムイオン二次電池用セパレータを提供することができる。 INDUSTRIAL APPLICABILITY In the present invention, a separator for a lithium ion secondary battery with a process film that prevents curling that occurs during the formation of the porous film and breakage of the porous film that occurs when the porous film is peeled from the process film can be provided. .
　以下、本発明の工程フィルム付きリチウムイオン二次電池用セパレータ（以下、「工程フィルム付きセパレータ」と略す）の実施形態について詳細に説明をする。
　本発明の工程フィルム付きセパレータは、基材フィルム、及びその基材フィルムの一方の面上に設けられたシリコーン樹脂組成物の硬化層を有する工程フィルムと、この硬化層の上に設けられ、微粒子（Ａ）と樹脂バインダ（Ｂ）を含有する多孔質膜からなるリチウムイオン二次電池用セパレータとを備えるものである。 Hereinafter, embodiments of a separator for a lithium ion secondary battery with a process film of the present invention (hereinafter abbreviated as “separator with a process film”) will be described in detail.
The separator with a process film of the present invention includes a base film, a process film having a cured layer of a silicone resin composition provided on one surface of the base film, and a fine film provided on the cured layer. (A) and the separator for lithium ion secondary batteries which consists of a porous film containing a resin binder (B).
　微粒子（Ａ）としては耐熱性および電気絶縁性を有し、化学的および電気化学的に安定であれば特に制限なく使用できる。なお、本明細書において「耐熱性」とは、少なくとも１５０℃で軟化などによる実質的な寸法変化、化学的な組成変化が生じないことを意味する。また、本明細書において「化学的に安定」とは、電解液中での形態変化、化学反応による組成変化を生じないことを意味する。また、本明細書において「電気化学的に安定」とは、リチウムイオン二次電池中で電気化学的な酸化還元反応による副反応が生じないことを意味する。 The fine particles (A) can be used without particular limitation as long as they have heat resistance and electrical insulation and are chemically and electrochemically stable. In the present specification, “heat resistance” means that substantial dimensional change and chemical composition change due to softening or the like do not occur at least at 150 ° C. Further, in the present specification, “chemically stable” means that there is no change in form in the electrolytic solution and no change in composition due to a chemical reaction. Further, in this specification, “electrochemically stable” means that a side reaction due to an electrochemical redox reaction does not occur in a lithium ion secondary battery.
　微粒子（Ａ）としては、特に制限はないが、例えばベーマイト、シリカ、酸化チタン、酸化マグネシウム、アルミナなどが挙げられ、好ましくはベーマイトを使用する。また、微粒子（Ａ）には電気絶縁性の向上や溶媒への分散性の向上を目的とした修飾を施してもよい。これらの微粒子は単独で使用してもよく、２種以上を併用してもよい。 The fine particles (A) are not particularly limited, and examples thereof include boehmite, silica, titanium oxide, magnesium oxide, and alumina. Preferably, boehmite is used. The fine particles (A) may be modified for the purpose of improving electrical insulation and dispersibility in a solvent. These fine particles may be used alone or in combination of two or more.
　微粒子（Ａ）のサイズとしては、平均粒径０．１μｍ以上５μｍ以下が望ましい。平均粒径を０．１μｍ以上とすると、多孔質膜の孔径が適切な大きさとなり、多孔質膜中のイオン伝導度が向上し、リチウムイオン二次電池の電池特性を良好とすることができる。また、平均粒径を５μｍ以下とすると、多孔質膜の孔径が大きくなりすぎることが防止され、リチウムデンドライドによる短絡が起こりにくくなる。
　微粒子（Ａ）の形状としては特に制限はなく、針状や板状、球状などでもよい。
　なお、本明細書において微粒子（Ａ）の平均粒径とは、レーザー回折式粒度分布計で測定した数平均粒子径である。 The size of the fine particles (A) is desirably an average particle size of 0.1 μm or more and 5 μm or less. When the average particle size is 0.1 μm or more, the pore size of the porous membrane becomes an appropriate size, the ionic conductivity in the porous membrane is improved, and the battery characteristics of the lithium ion secondary battery can be improved. . Moreover, when the average particle diameter is 5 μm or less, the pore diameter of the porous film is prevented from becoming too large, and short-circuiting due to lithium dendride hardly occurs.
There is no restriction | limiting in particular as a shape of microparticles | fine-particles (A), Needle shape, plate shape, spherical shape etc. may be sufficient.
In the present specification, the average particle size of the fine particles (A) is the number average particle size measured with a laser diffraction particle size distribution meter.
　樹脂バインダ（Ｂ）としては耐熱性および電気絶縁性を有し、化学的および電気化学的安定で、上記微粒子（Ａ）を好適に接着することができる樹脂であればよい。
　樹脂バインダ（Ｂ）としては、特に制限はなく、様々なものを用いることができ、例えば、ポリフッ化フルオロエチレン（ＰＴＦＥ）、ポリクロロトリフルオロエチレン（ＰＣＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリフッ化ビニル（ＰＶＦ）などのフッ素系樹脂、ポリアミド系樹脂、ポリイミド系樹脂、エチレン－酢酸ビニル共重合体、エチレン－エチルアクリレート共重合体、フッ素系ゴム、スチレン－ブタジエンゴム（ＳＢＲ）、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ポリビニルアルコール、ポリビニルブチラール、ポリビニルピロリドン、ウレタン系樹脂、エポキシ系樹脂、ポリエチレンテレフタレート等のポリエステル系樹脂などが挙げられる。これらの樹脂は単独で使用してもよく、２種以上を併用してもよい。
　樹脂バインダ（Ｂ）としては、これらの中では、ポリフッ化フルオロエチレン、ポリクロロトリフルオロエチレン、ポリフッ化ビニリデン、ポリフッ化ビニルなどのフッ素系樹脂が好ましく、ポリフッ化ビニリデンがより好ましく使用される。本発明では、フッ素系樹脂を使用することで、多孔質膜に高い耐久性と電気絶縁性を付与することができる。また、フッ素系樹脂を使用した場合には、多孔質膜にカールが発生しやすく、工程フィルムからの剥離時に破損がより生じやすいが、本発明では、そのようなカールの発生や、剥離時の破損を適切に防止できる。 The resin binder (B) may be any resin that has heat resistance and electrical insulation, is chemically and electrochemically stable, and can favorably adhere the fine particles (A).
The resin binder (B) is not particularly limited, and various types can be used. For example, polyfluorinated fluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyfluorinated Fluorine resin such as vinyl (PVF), polyamide resin, polyimide resin, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, fluorine rubber, styrene-butadiene rubber (SBR), carboxymethylcellulose, hydroxy Examples thereof include polyester resins such as ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, urethane resins, epoxy resins, and polyethylene terephthalate. These resins may be used alone or in combination of two or more.
Of these, the resin binder (B) is preferably a fluorine-based resin such as polyfluorinated fluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, or polyvinyl fluoride, and more preferably polyvinylidene fluoride. In the present invention, high durability and electrical insulation can be imparted to the porous membrane by using a fluororesin. In addition, when a fluororesin is used, the porous membrane is likely to curl and more easily damaged when peeled off from the process film. Damage can be prevented appropriately.
　樹脂バインダ（Ｂ）の分子量としては重量平均分子量１００,０００以上２，０００，０００以下が好ましく、より好ましくは５００，０００以上１，５００，０００以下である。重量平均分子量を上記下限値以上とすることにより、多孔質膜の強度を良好にすることができ、例えば、リチウムデンドライドが発生しても、そのリチウムデンドライドにより多孔質膜が破られることが防止され、短絡が生じにくくなる。また、上記上限値以下とすることにより、多孔質膜形成用組成物の粘度を適切なものにでき、工程フィルムの硬化層の上に多孔質膜形成用組成物を均一に塗布しやすくなる。
　なお、本明細書において重量平均分子量とは、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）法により測定した標準ポリスチレン換算値である。 The molecular weight of the resin binder (B) is preferably a weight average molecular weight of 100,000 to 2,000,000, more preferably 500,000 to 1,500,000. By setting the weight average molecular weight to the above lower limit value or more, the strength of the porous film can be improved. For example, even when lithium dendride is generated, the porous film can be broken by the lithium dendride. This prevents the short circuit from occurring. Moreover, by setting it as the said upper limit or less, the viscosity of the composition for porous film formation can be made suitable, and it becomes easy to apply | coat the composition for porous film formation uniformly on the hardening layer of a process film.
In this specification, the weight average molecular weight is a standard polystyrene equivalent value measured by gel permeation chromatography (GPC).
　多孔質膜中の微粒子（Ａ）は４０体積％以上８５体積％以下が好ましく、より好ましくは６０体積％以上８０体積％以下である。この体積比率範囲内の多孔質膜は、工程フィルムの硬化層に対して良好な剥離力を有する。また、体積比率を上記下限値以上とすることで、多孔質膜の空孔率が適切なものとなり、多孔質膜中のイオン伝導率を向上させて、リチウムイオン二次電池の電池特性を良好にすることができる。また、体積比率を上記上限値以下とすることで、樹脂バインダ（Ｂ）の体積比率を所定値以上とすることができ、多孔質膜の強度を良好に保つことができる。 The fine particles (A) in the porous film are preferably 40% by volume or more and 85% by volume or less, more preferably 60% by volume or more and 80% by volume or less. The porous film within the volume ratio range has a good peeling force with respect to the cured layer of the process film. Also, by setting the volume ratio to the above lower limit or more, the porosity of the porous membrane becomes appropriate, and the ionic conductivity in the porous membrane is improved, and the battery characteristics of the lithium ion secondary battery are good. Can be. Moreover, by setting the volume ratio to be equal to or less than the above upper limit value, the volume ratio of the resin binder (B) can be set to a predetermined value or more, and the strength of the porous film can be kept good.
　多孔質膜の膜厚は特に制限されないが、１０μｍ以上３０μｍ以下が好ましい。膜厚を１０μｍ以上とすることで、多孔質膜の強度を十分なものとすることができる。また膜厚を３０μｍ以下とすることで、イオン伝導パスを適切な長さとし、リチウムイオン二次電池の電池特性を良好にすることができる。
　多孔質膜の空孔率は特に制限されないが、３０％以上８０％以下が好ましい。空孔率を３０％以上とすることで、イオン伝導率が減少することを防止できる。また空孔率を８０％以下とすることで、多孔質膜の強度が低下することを防止できる。 The thickness of the porous membrane is not particularly limited, but is preferably 10 μm or more and 30 μm or less. By setting the film thickness to 10 μm or more, the strength of the porous film can be made sufficient. In addition, by setting the film thickness to 30 μm or less, the ion conduction path can be set to an appropriate length, and the battery characteristics of the lithium ion secondary battery can be improved.
The porosity of the porous membrane is not particularly limited, but is preferably 30% or more and 80% or less. By setting the porosity to 30% or more, it is possible to prevent the ionic conductivity from decreasing. Moreover, it can prevent that the intensity | strength of a porous film falls by making a porosity into 80% or less.
　シリコーン樹脂組成物の硬化層は、多孔質膜形成用組成物に対して安定であり、多孔質膜を適切に剥離できるものであれば良い。本明細書中における「多孔質膜形成用組成物に対して安定」とは、多孔質膜の製造工程中に、多孔質膜形成用組成物中において、形態変化が生じたり、化学反応による組成変化が生じたりしないことを意味する。シリコーン樹脂組成物としては、硬化層を後述するように所定の弾性率とすることができるものならば、特に制限はなく、様々なものを用いることができる。例えば付加反応型シリコーン樹脂、架橋剤、及び触媒を含有する付加反応型シリコーン樹脂組成物が挙げられるがこの限りではない。また所望により光増感剤、付加反応抑制剤、シリコーンガムやシリコーンワニスなどの剥離調整剤、密着向上剤などを加えてもよい。 The cured layer of the silicone resin composition may be any material that is stable with respect to the composition for forming a porous film and can appropriately peel the porous film. In the present specification, “stable with respect to the composition for forming a porous film” means that the composition for forming a porous film undergoes a morphological change or a chemical reaction during the production process of the porous film. It means that no change occurs. The silicone resin composition is not particularly limited as long as the cured layer can have a predetermined elastic modulus as described later, and various types can be used. Examples thereof include, but are not limited to, an addition reaction type silicone resin, a crosslinking agent, and an addition reaction type silicone resin composition containing a catalyst. Further, if desired, a photosensitizer, an addition reaction inhibitor, a release adjusting agent such as silicone gum or silicone varnish, and an adhesion improving agent may be added.
　付加反応型シリコーン樹脂としては特に制限はなく、様々なものを使用することができる。例えば分子中に官能基としてアルケニル基を有するポリオルガノシロキサンなどが挙げられる。
　架橋剤は、シリコーン樹脂組成物を硬化させるためのものであって、例えば１分子中にケイ素原子に結合した水素原子を有する官能基を少なくとも２個有するポリオルガノシロキサンが挙げられる。架橋剤の使用量は、付加反応型シリコーン樹脂１００質量部に対し、０．３質量部以上５０質量部以下が好ましい。
　触媒としては通常白金系触媒が用いられる。この白金系触媒の例としては、微粒子状白金、炭素粉担体上に吸着された微粒子状白金、塩化白金酸、アルコール変性塩化白金酸、塩化白金酸のオレフィン錯体、パラジウム、ロジウム触媒などが挙げられる。触媒の使用量は、付加反応型シリコーン樹脂と架橋剤の合計量中に、白金系金属として１質量ｐｐｍ以上、１０００質量ｐｐｍ以下程度である。 There is no restriction | limiting in particular as addition reaction type silicone resin, A various thing can be used. Examples thereof include polyorganosiloxane having an alkenyl group as a functional group in the molecule.
The crosslinking agent is for curing the silicone resin composition, and examples thereof include polyorganosiloxane having at least two functional groups having hydrogen atoms bonded to silicon atoms in one molecule. The amount of the crosslinking agent used is preferably 0.3 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the addition reaction type silicone resin.
As the catalyst, a platinum-based catalyst is usually used. Examples of the platinum-based catalyst include particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, rhodium catalyst, and the like. . The usage-amount of a catalyst is about 1 mass ppm or more and about 1000 mass ppm or less as a platinum-type metal in the total amount of an addition reaction type silicone resin and a crosslinking agent.
　光増感剤としては特に制限はなく、様々なものを使用することができる。例えばベンゾイン類、ベンゾフェノン類、アセトフェノン類、α-ヒドロキシケトン類、α-アミノケトン類、α-ジケトン類、α-ジケトンアルキルアセタール類、アントラキノン類、チオキサントン類などが挙げられる。これら光増感剤は、単独で用いてもよく、２種以上を併用してもよい。また、その使用量は付加反応型シリコーン樹脂と架橋剤の合計量に対し、０．０５質量部以上２０質量部以下が好ましい。
　付加反応抑制剤は、シリコーン樹脂組成物の室温における保存安定性を付与するために用いられる成分である。付加反応抑制剤としては特に制限はなく、様々なものを使用することができる。例えば３，５-ジメチル-１-ヘキシン-３-オール、３-メチル-１-ペンテン-３-オール、３-メチル-３-ペンテン-１-イン、３，５-ジメチル-３-ヘキセン-１-イン、テトラビニルシロキサン環状体、ベンゾトリアゾールなどが挙げられる。
　剥離調整剤としては特に制限はなく、様々なものを使用することができる。例えばケイ素原子に結合したアルケニル基及び水素原子を有しないポリオルガノシロキサンなどが挙げられる。 There is no restriction | limiting in particular as a photosensitizer, A various thing can be used. Examples include benzoins, benzophenones, acetophenones, α-hydroxy ketones, α-amino ketones, α-diketones, α-diketone alkyl acetals, anthraquinones, thioxanthones, and the like. These photosensitizers may be used independently and may use 2 or more types together. The amount used is preferably 0.05 parts by mass or more and 20 parts by mass or less with respect to the total amount of the addition reaction type silicone resin and the crosslinking agent.
The addition reaction inhibitor is a component used for imparting storage stability of the silicone resin composition at room temperature. There is no restriction | limiting in particular as an addition reaction inhibitor, A various thing can be used. For example, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-penten-3-ol, 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexene-1 -In, tetravinylsiloxane cyclic, benzotriazole and the like.
There is no restriction | limiting in particular as a peeling regulator, Various things can be used. Examples thereof include alkenyl groups bonded to silicon atoms and polyorganosiloxanes having no hydrogen atoms.
　シリコーン樹脂組成物の硬化層の膜厚は特に制限されないが、４０ｎｍ以上３００ｎｍ以下が好ましい。膜厚を４０ｎｍ以上とすることで、シリコーン樹脂組成物を工程フィルムに塗布する際に塗工ムラが生じにくくし、均一な厚みの硬化層を形成することが可能になる。また、膜厚を３００ｎｍ以下とすることで、硬化層にタックが生じたりすることを防止し、多孔質膜に対して十分な離型性を得ることができるようになる。 The thickness of the cured layer of the silicone resin composition is not particularly limited, but is preferably 40 nm or more and 300 nm or less. By setting the film thickness to 40 nm or more, coating unevenness hardly occurs when the silicone resin composition is applied to the process film, and a cured layer having a uniform thickness can be formed. Further, by setting the film thickness to 300 nm or less, it is possible to prevent the cured layer from being tacked and to obtain sufficient release properties for the porous film.
　本発明では、工程フィルムにおけるシリコーン樹脂組成物の硬化層は、その弾性率が０．１５ＧＰａ以上となるものである。弾性率は好ましくは０．２０ＧＰａ以上、より好ましくは０．２５ＧＰａ以上である。弾性率を０．１５ＧＰａ未満とすると、シリコーン樹脂組成物の硬化層に多孔質膜形成用組成物中の樹脂バインダが浸み込み、工程フィルムが多孔質膜に対して十分な離型性を得ることができないおそれがある。また、弾性率を０．２５ＧＰａ以上とすることにより、剥離性能がさらに良好になり、特に高速剥離時の剥離性能を良好にすることができる。
　また、シリコーン樹脂組成物の硬化層の弾性率は、特に限定されないが、一般的には組成の観点から官能基を有するポリオルガノシロキサンではおよそ１．０ＧＰａ以下、好ましくは０．５ＧＰａ以下である。
　なお、硬化層の弾性率は、公知の方法で測定することができるが、本明細書においては、硬化層の表面からナノインデンターにより測定される弾性率であり、実施例で説明する方法で求めることができる。 In the present invention, the cured layer of the silicone resin composition in the process film has an elastic modulus of 0.15 GPa or more. The elastic modulus is preferably 0.20 GPa or more, more preferably 0.25 GPa or more. When the elastic modulus is less than 0.15 GPa, the resin binder in the porous film forming composition soaks into the cured layer of the silicone resin composition, and the process film has sufficient releasability from the porous film. There is a possibility that it cannot be done. Further, when the elastic modulus is 0.25 GPa or more, the peeling performance is further improved, and the peeling performance at the time of high-speed peeling can be particularly improved.
The elastic modulus of the cured layer of the silicone resin composition is not particularly limited, but is generally about 1.0 GPa or less, preferably 0.5 GPa or less for a polyorganosiloxane having a functional group from the viewpoint of composition.
The elastic modulus of the cured layer can be measured by a known method, but in the present specification, it is an elastic modulus measured by a nanoindenter from the surface of the cured layer, and the method described in the examples. Can be sought.
　工程フィルムで使用される基材フィルムは、所定の乾燥温度に対して、軟化などによる実質的な寸法変化、化学的な組成変化が生じないものが使用される。基材フィルムとしては特に制限はなく、様々なものを使用することができる。例えばポリエチレンテレフタレートやポリエチレンナフタレートなどのポリエステルフィルム、ポリプロピレンやポリメチルペンテンなどのポリオレフィンフィルム、ポリカーボネートフィルム、ポリ酢酸ビニルフィルムなどを挙げることができるが、好ましくはポリエステルフィルム、特に二軸延伸ポリエチレンテレフタレートフィルムが好ましい。
　また、基材フィルムの厚さは、後述するように所定の剛軟度を得ることができるものならば特に限定されないが、例えば５０μｍ以上１５０μｍ以下、好ましくは６０μｍ以上１２０μｍ以下である。基材フィルムの厚さが上記範囲であれば、後述する所定の剛軟度を容易に得ることができる。 As the base film used in the process film, a base film that does not undergo substantial dimensional change or chemical composition change due to softening or the like with respect to a predetermined drying temperature is used. There is no restriction | limiting in particular as a base film, A various thing can be used. Examples include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyolefin films such as polypropylene and polymethylpentene, polycarbonate films, and polyvinyl acetate films. Polyester films, particularly biaxially stretched polyethylene terephthalate films are preferred. preferable.
The thickness of the base film is not particularly limited as long as a predetermined bending resistance can be obtained as will be described later, but is, for example, 50 μm or more and 150 μm or less, preferably 60 μm or more and 120 μm or less. If the thickness of the base film is within the above range, a predetermined bending resistance described later can be easily obtained.
　工程フィルムの硬化層側の離型性は、多孔質膜形成後のスリット工程、巻き取り工程などで多孔質膜が工程フィルムから剥離することがなく、また、多孔質膜を工程フィルムから剥離する剥離工程において、多孔質膜が形状変化したり、破損が生じたりしない程度であればよい。具体的には、剥離速度０．３ｍ／分および１０ｍ／分にて剥離角度１８０°で、多孔質膜を工程フィルムから剥離した際の剥離力が、それぞれの剥離速度において共に１０ｍＮ／５０ｍｍ以上４００ｍＮ／５０ｍｍ以下であることが好ましく、より好ましくは４０ｍＮ／５０ｍｍ以上１００ｍＮ／５０ｍｍ以下である。剥離力を上記下限値以上とすることで、多孔質膜形成後のスリット工程、巻き取り工程等の意図しないときに、多孔質膜が工程フィルムから浮き上がって多孔質膜が剥離することを防止できる。また上記上限値以下とすることで、多孔質膜を工程フィルムから剥離する際に多孔質膜に形状変化が生じたり、破損が生じたりすることを防止できる。 The releasability on the cured layer side of the process film is such that the porous film does not peel from the process film in the slit process or winding process after the porous film is formed, and the porous film is peeled off from the process film. In the peeling step, it is sufficient that the porous film does not change its shape or breakage occurs. Specifically, the peeling force when peeling the porous membrane from the process film at a peeling speed of 0.3 m / min and 10 m / min at a peeling angle of 180 ° is 10 mN / 50 mm or more and 400 mN at each peeling speed. / 50 mm or less, more preferably 40 mN / 50 mm or more and 100 mN / 50 mm or less. By setting the peeling force to the above lower limit or more, it is possible to prevent the porous film from being lifted off from the process film and being peeled off when the slit process or the winding process after the porous film formation is not intended. . Moreover, by setting it as the said upper limit or less, when peeling a porous film from a process film, it can prevent that a shape change arises in a porous film, or a damage arises.
　工程フィルムの硬化層表面の算術平均粗さは、１５．０ｎｍ以下であることが好ましい。算術平均粗さを１５．０ｎｍ以下とすることで、工程フィルムの硬化層上に形成された多孔質膜が硬化層に食い込むことが抑制され、多孔質膜を剥離する際に形状変化が生じたり、破損が生じたりすることが防止される。
　また、工程フィルムの硬化層表面の最大断面高さは、２００．０ｎｍ以下であることが好ましい。最大断面高さを２００．０ｎｍ以下とすることで、工程フィルムの硬化層上に形成された多孔質膜が硬化層に食い込むことが抑制され、多孔質膜を剥離する際に形状変化が生じたり、破損が生じたりすることが防止される。 The arithmetic average roughness of the cured layer surface of the process film is preferably 15.0 nm or less. By setting the arithmetic average roughness to 15.0 nm or less, the porous film formed on the cured layer of the process film is prevented from biting into the cured layer, and a shape change occurs when the porous film is peeled off. It is prevented that damage occurs.
Moreover, it is preferable that the maximum cross-sectional height of the hardened layer surface of a process film is 200.0 nm or less. By setting the maximum cross-sectional height to 200.0 nm or less, the porous film formed on the cured layer of the process film is prevented from biting into the cured layer, and a shape change occurs when the porous film is peeled off. It is prevented that damage occurs.
　本発明の工程フィルムは、ガーレ法による剛軟度が０．３ｍＮ以上となるものである。本発明では、後述するように工程フィルムに多孔質膜形成用組成物を塗布・乾燥することにより多孔質膜が形成される。この乾燥工程において多孔質膜には、熱収縮が生じようとするが、上記剛軟度が０．３ｍＮ未満となると、工程フィルムはその熱収縮に対して十分に抵抗することができず、工程フィルム付きセパレータに大きなカールが生じることになる。上記剛軟度を有した工程フィルムは、多孔質膜の熱収縮に対して十分に耐性があり、カールをより良好に抑制できるようにするために、剛軟度は、０．５ｍＮ以上であることが好ましく、０．７５ｍＮ以上であることがより好ましい。また、剛軟度は、得られる工程フィルム付きセパレータをロール状に巻けるようにするために４．０ｍＮ以下であることが好ましく、２．０ｍＮ以下であることがより好ましい。
　なお、本発明におけるガーレ法による剛軟度とは、ＪＩＳ Ｌ－１０９６　Ａ法（ガーレ法）に準拠して、測定したものをいう。 The process film of the present invention has a bending resistance by the Gurley method of 0.3 mN or more. In the present invention, as described later, the porous film is formed by applying and drying the porous film-forming composition on the process film. In this drying process, the porous film tends to undergo heat shrinkage. However, if the bending resistance is less than 0.3 mN, the process film cannot sufficiently resist the heat shrinkage. A big curl will arise in a separator with a film. The process film having the bending resistance is sufficiently resistant to the heat shrinkage of the porous film, and the bending resistance is 0.5 mN or more so that curling can be more effectively suppressed. It is preferable, and it is more preferable that it is 0.75 mN or more. In addition, the bending resistance is preferably 4.0 mN or less, and more preferably 2.0 mN or less so that the separator with a process film to be obtained can be wound into a roll.
In the present invention, the bending resistance by the Gurley method means a value measured in accordance with the JIS L-1096 A method (Gurley method).
　本発明の工程フィルム付きセパレータは、微粒子（Ａ）と、樹脂バインダ（Ｂ）とを含有する多孔質膜形成用組成物を、工程フィルムの硬化層の上に公知の方法で塗布し、所定の温度で乾燥することで製造することができる。このとき、乾燥温度は１２０～１８０℃、乾燥時間は例えば６０～３００秒である。また、塗布方法としては、特に限定されないが、ディップコート、ダイコート、バーコート、ドクターブレード等が挙げられる。 In the separator with a process film of the present invention, a porous film-forming composition containing fine particles (A) and a resin binder (B) is applied onto a cured layer of a process film by a known method, It can be produced by drying at a temperature. At this time, the drying temperature is 120 to 180 ° C., and the drying time is, for example, 60 to 300 seconds. The application method is not particularly limited, and examples thereof include dip coating, die coating, bar coating, and doctor blade.
　多孔質膜形成用組成物は、微粒子（Ａ）及び樹脂バインダ（Ｂ）に加え、溶媒（Ｃ）を含有し、溶媒（Ｃ）に微粒子（Ａ）を分散させ、樹脂バインダ（Ｂ）を分散もしくは溶解させたものである。溶媒（Ｃ）は微粒子（Ａ）を均一に分散させ、樹脂バインダ（Ｂ）を均一に分散もしくは溶解させることができるものであればよく、特に制限はなく様々なものを使用することができる。例えば、Ｎ-メチルピロリドン（ＮＭＰ）、ジメチルアセトアミド、ジメチルホルムアミド、テトラヒドロフラン、ジメチルスルホキシド、トリエチルフォスフェート、メチルエチルケトン、メチルイソブチルケトンなどが挙げられるが、好ましくはＮ-メチルピロリドン（ＮＭＰ）を使用する。 The composition for forming a porous film contains the solvent (C) in addition to the fine particles (A) and the resin binder (B), and the fine particles (A) are dispersed in the solvent (C) to disperse the resin binder (B). Alternatively, it is dissolved. The solvent (C) is not particularly limited as long as it can uniformly disperse the fine particles (A) and can uniformly disperse or dissolve the resin binder (B), and various solvents can be used. For example, N-methylpyrrolidone (NMP), dimethylacetamide, dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, triethyl phosphate, methyl ethyl ketone, methyl isobutyl ketone and the like can be mentioned, and N-methylpyrrolidone (NMP) is preferably used.
　工程フィルムの硬化層は、多孔質膜を形成するために使用した溶媒（Ｃ）に対する接触角が、５５°以上７５°以下であることが好ましい。接触角を５５°以上とすることで、シリコーン樹脂組成物の硬化層を有する工程フィルムが多孔質膜に対して十分な離型性を得ることができるようになる。また接触角を７５°以下とすることで、多孔質膜形成用組成物を工程フィルムの硬化層に塗布した際にはじきが生じることが防止され、均一な多孔質膜を得ることができるようになる。 The cured layer of the process film preferably has a contact angle with respect to the solvent (C) used for forming the porous film of 55 ° or more and 75 ° or less. By setting the contact angle to 55 ° or more, the process film having a cured layer of the silicone resin composition can obtain sufficient releasability from the porous film. Further, by setting the contact angle to 75 ° or less, it is possible to prevent occurrence of repellency when the composition for forming a porous film is applied to the cured layer of the process film, and to obtain a uniform porous film. Become.
　多孔質膜形成用組成物の固形分濃度は特に制限しないが、２０質量％以上６０質量％以下が好ましい。固形分濃度を上記範囲内とすることで、多孔質膜形成用組成物の粘度が適切な値となり、所定の膜厚を得るための必要な塗布量を得ることができるとともに、多孔質膜形成用組成物を均一に塗布できるようになる。 The solid content concentration of the composition for forming a porous film is not particularly limited, but is preferably 20% by mass or more and 60% by mass or less. By setting the solid content concentration within the above range, the viscosity of the composition for forming a porous film becomes an appropriate value, and a necessary coating amount for obtaining a predetermined film thickness can be obtained. The composition can be applied uniformly.
　一般的に上記のように製造した工程フィルム付きセパレータは、適当な幅長さを有するように必要に応じてスリットされ、その後、ロール状に巻き取られる。
　また、本発明の工程フィルム付きセパレータを用いて、多孔質膜に正極および負極を積層して、リチウムイオン二次電池に使用される積層電極体を得る方法は、特に限定されないが、例えば以下の方法が挙げられる。ロール状にされた工程フィルム付きセパレータを、巻き出しながら、かつ工程フィルムを巻き取りロールに巻き取らせることにより多孔質膜を工程フィルムから剥離し、その剥離した多孔質膜に正極および負極を積層する。このとき、正極および負極は、ロールから巻き出したものであってもよいし、なくてもよい。 Generally, the separator with a process film manufactured as described above is slit as necessary so as to have an appropriate width and length, and then wound into a roll.
In addition, the method of obtaining a laminated electrode body used for a lithium ion secondary battery by laminating a positive electrode and a negative electrode on a porous film using the separator with a process film of the present invention is not particularly limited. A method is mentioned. The separator with a roll-formed process film is unwound and the process film is wound on a take-up roll to peel the porous film from the process film, and the positive electrode and the negative electrode are laminated on the peeled porous film. To do. At this time, the positive electrode and the negative electrode may or may not be unwound from the roll.
　以上のように、本発明では、シリコーン樹脂組成物の硬化層の弾性率を０．１５ＧＰａ以上とするとともに、工程フィルムの剛軟度を０．３ｍＮ以上とすることにより、工程フィルム付きセパレータにカールが発生せず、さらには多孔質膜を工程フィルムから剥離する際に生じる多孔質膜の破損も防止することができる。このように、本発明の多孔質膜は、破損やカール等が生じにくいから、取り扱い性に優れ、薄層化もしやすくなる。 As described above, in the present invention, the elastic modulus of the cured layer of the silicone resin composition is set to 0.15 GPa or more and the bending resistance of the process film is set to 0.3 mN or more to curl the separator with the process film. Can be prevented, and furthermore, damage to the porous membrane that occurs when the porous membrane is peeled from the process film can be prevented. As described above, the porous film of the present invention is less likely to be damaged or curled, and thus has excellent handleability and is easily thinned.
　以下、実施例に基づき本発明をさらに詳細に説明するが、本発明はこれらの例によって制限されるものではない。 Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
本発明における各物性の測定方法は、以下のとおりである。
（１）硬化層の弾性率
　シリコーン樹脂組成物の硬化層を有する工程フィルムを温度２３℃、相対湿度５０％の条件下に２４時間放置後、硬化層の弾性率を測定した。このとき、工程フィルムをコニシ株式会社製ボンドクイック５を用いてガラス板上に固定し、硬化層の表面からＮＴＳ社製ＮａｎｏＩｎｄｅｎｔｅｒ　ＳＡ２を用いて、温度２３℃、相対湿度５０％の下で測定を行った。硬化層の弾性率は、硬化層の表面から５～１０ｎｍの深度の範囲内で測定した２０点の値の平均値で算出した。
（２）剛軟度
　ＪＩＳ－Ｌ１０９６　Ａ法に規定されるガーレ法に準拠して、工程フィルムを長さ３８ｍｍ、幅２５ｍｍの試験片とし、ガーレ式剛軟度測定器（株式会社安田精機製作所）を使用し、荷重５ｇにて測定した。ｎ＝５の試験片の表裏を測定し、平均値を算出した。
（３）工程フィルムの硬化層の溶媒（ＮＭＰ）に対する接触角
　シリコーン樹脂組成物の硬化層を有する工程フィルムを温度２３℃、相対湿度５０％の条件下に２４時間放置後、硬化層のＮＭＰに対する接触角を測定した。測定はＫＲＵＳＳ社製ＤＳＡ１００Ｓを用いて行った。
（４）工程フィルムの硬化層の算術平均表面粗さ、最大断面高さ
　シリコーン樹脂組成物の硬化層を有する工程フィルムを温度２３℃、相対湿度５０％の条件下に２４時間放置後、工程フィルムの硬化層が設けられた面について、４５０μｍ×６００μｍの範囲にて算術平均粗さと最大断面高さを測定した。測定はＶｅｅｃｏ社製Ｗｙｋo  ＮＴ１１００を用いて行った。
（５）工程フィルムの多孔質膜に対する剥離力
　工程フィルム付きセパレータを温度２３℃、相対湿度５０％の条件下に２４時間放置後、５０ｍｍ幅、１５０ｍｍ長さに裁断し、工程フィルムを固定し、引張試験機を用いて１８０°の角度で０．３ｍ／分および１０ｍ／分の速度で多孔質膜を剥がし、そのときの剥離に要する力（剥離力）を測定した。
（６）カール量
　工程フィルム付きセパレータについて、２０×２０ｃｍに裁断し、シートサンプルを作成した。次いで、温度２３℃、相対湿度５０％の環境下で、シートの端辺の中心部を摘んで吊るし、ハンギングカール量を測定することにより評価した。なお、表欄の括弧内は、カール軸の方向を示す。なお、本明細書において、ＣＤ方向とは、工程フィルム及び工程フィルム付きセパレータの製造ラインの流れ方向と直交する方向をいう。
（７）平均粒径
　レーザー回折式粒度分布測定により微粒子（Ａ）の数平均粒子径を算出した。測定は株式会社堀場製作所製ＬＡ－９２０を用いた。微粒子（Ａ）を水に分散させた後に、５３２ｎｍでの透過率が７０～９０％となるように希釈し、溶媒と微粒子（Ａ）の屈折率より算出した数平均粒子径である。
（８）重量平均分子量
　樹脂バインダ（Ｂ）をテトラヒドロフランに溶解させ、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いて温度４０℃で測定し、標準ポリスチレン換算値を算出した。測定は東ソー社製ＨＬＣ－８０２０を用い、東ソー社製ＧＰＣカラムであるＴＳＫｇｕａｒｄｃｏｌｕｍｎＨＸＬ－Ｈ、ＴＳＫｇｅｌＧＭＨＸＬ（×２）、ＴＳＫｇｅｌＧ２０００ＨＸＬを順に通過させた。 The measuring method of each physical property in the present invention is as follows.
(1) Elastic modulus of cured layer The process film having a cured layer of the silicone resin composition was allowed to stand for 24 hours under conditions of a temperature of 23 ° C and a relative humidity of 50%, and then the elastic modulus of the cured layer was measured. At this time, the process film was fixed on a glass plate using Bond Quick 5 manufactured by Konishi Co., Ltd., and measured at a temperature of 23 ° C. and a relative humidity of 50% using NanoInstant SA2 manufactured by NTS from the surface of the cured layer. went. The elastic modulus of the cured layer was calculated as an average value of 20 points measured within a depth range of 5 to 10 nm from the surface of the cured layer.
(2) Bending softness In accordance with the Gurley method stipulated in JIS-L1096 A method, the process film is a test piece having a length of 38 mm and a width of 25 mm, and a Gurley type bending resistance measuring instrument (Yasuda Seiki Seisakusho Co., Ltd.) And measured at a load of 5 g. The front and back of the test piece of n = 5 were measured, and the average value was calculated.
(3) Contact angle of cured layer of process film to solvent (NMP) A process film having a cured layer of the silicone resin composition is allowed to stand for 24 hours at a temperature of 23 ° C. and a relative humidity of 50%. The contact angle was measured. The measurement was performed using DSA100S manufactured by KRUSS.
(4) Arithmetic average surface roughness and maximum cross-sectional height of the cured layer of the process film The process film having the cured layer of the silicone resin composition is allowed to stand for 24 hours at a temperature of 23 ° C. and a relative humidity of 50%. The arithmetic average roughness and the maximum cross-sectional height were measured in the range of 450 μm × 600 μm on the surface provided with the cured layer. The measurement was performed using Wyko NT1100 manufactured by Veeco.
(5) Peeling force of the process film on the porous membrane After leaving the separator with the process film at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, it is cut into a width of 50 mm and a length of 150 mm, and the process film is fixed. Using a tensile tester, the porous film was peeled off at an angle of 180 ° at a speed of 0.3 m / min and 10 m / min, and the force (peeling force) required for peeling at that time was measured.
(6) Curling amount About the separator with a process film, it cut | judged to 20x20 cm and created the sheet sample. Next, in an environment of a temperature of 23 ° C. and a relative humidity of 50%, the center portion of the edge of the sheet was picked and hung and evaluated by measuring the amount of hanging curl. The parentheses in the table column indicate the direction of the curl axis. In addition, in this specification, CD direction means the direction orthogonal to the flow direction of the manufacturing line of a process film and a separator with a process film.
(7) Average particle size The number average particle size of the fine particles (A) was calculated by laser diffraction particle size distribution measurement. For the measurement, LA-920 manufactured by Horiba Ltd. was used. The number average particle diameter is calculated from the refractive index of the solvent and the fine particles (A) after the fine particles (A) are dispersed in water and diluted so that the transmittance at 532 nm is 70 to 90%.
(8) Weight average molecular weight The resin binder (B) was dissolved in tetrahydrofuran and measured at a temperature of 40 ° C. using gel permeation chromatography (GPC) to calculate a standard polystyrene equivalent value. For the measurement, HLC-8020 manufactured by Tosoh Corporation was used, and TSKguardcolumnHXL-H, TSKgelGMHXL (× 2), and TSKgelG2000HXL, which are GPC columns manufactured by Tosoh Corporation, were passed in order.
実施例１
　微粒子（Ａ）である密度２．９６ｇ／ｃｍ3、平均粒径０．２μｍのベーマイト微粒子、樹脂バインダ（Ｂ）である密度１．７８ｇ／ｃｍ3、重量平均分子量１，０００，０００のポリフッ化ビニリデンを、全固形分中の微粒子（Ａ）が７０体積％となるように配合し、溶媒（Ｃ）であるＮ－メチルピロリドンを、全固形分濃度が３０質量％となるように容器に入れ、メカニカルスターラーで２時間撹拌することで、均一に分散したスラリー状の多孔質膜形成用組成物を調製した。次いで、基材フィルムである厚さ７５μｍのポリエチレンテレフタレートフィルムの一方の面の上に、シリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＤＳ７５２１６０」）の硬化層上に、上記多孔質膜形成用組成物を、乾燥後の膜厚が２０μｍとなるようにコンマコーターを用いて均一に塗工し、１５０℃で１５０秒間乾燥させることで工程フィルム付きセパレータを製造した。 Example 1
The fine particles (A) have a density of 2.96 g / cm 3 , boehmite fine particles having an average particle diameter of 0.2 μm, and the resin binder (B) has a density of 1.78 g / cm 3 and a weight average molecular weight of 1,000,000 polyfluorination. Vinylidene is blended so that the fine particles (A) in the total solids are 70% by volume, and N-methylpyrrolidone as the solvent (C) is put in a container so that the total solids concentration is 30% by mass. By stirring with a mechanical stirrer for 2 hours, a uniformly dispersed slurry-like composition for forming a porous film was prepared. Next, on one side of a 75 μm-thick polyethylene terephthalate film, which is a base film, on a cured layer of a process film (trade name “PDS752160”, manufactured by Lintec Corporation) having a cured layer of a silicone resin composition The porous film-forming composition was uniformly applied using a comma coater so that the film thickness after drying was 20 μm, and dried at 150 ° C. for 150 seconds to produce a separator with a process film.
実施例２
　工程フィルムとして、基材フィルムである厚さ１００μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＤＳ１００２１６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Example 2
The point which used the process film (The product name "PDS1002160" by Lintec Corporation) which has the hardened layer of a silicone resin composition on one surface of the polyethylene terephthalate film of thickness 100 micrometers which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
実施例３
　工程フィルムとして、基材フィルムである厚さ７５μｍのポリエチレンテレフタレートフィルムの一方の面上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＤ７５２０６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Example 3
Other than the use of a process film (trade name “PLD752060”, manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 75 μm-thick polyethylene terephthalate film, which is a base film, as the process film Produced a separator with a process film in the same manner as in Example 1.
実施例４
　工程フィルムとして、基材フィルムである厚さ１００μｍのポリエチレンテレフタレートフィルムの一方の面上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＤ１００２０６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Example 4
Other than the use of a process film having a cured layer of a silicone resin composition on one surface of a 100 μm-thick polyethylene terephthalate film as a process film (product name “PLD1002060” manufactured by Lintec Corporation) as the process film Produced a separator with a process film in the same manner as in Example 1.
実施例５
　工程フィルムとして、基材フィルムである厚さ７５μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＳ７５Ｔ１６１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Example 5
The point which used the process film (the product name "PLS75T161" by Lintec Co., Ltd.) which has the hardened layer of a silicone resin composition on one surface of the 75-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
実施例６
　工程フィルムとして、基材フィルムである厚さ１００μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＳ１００Ｔ１６１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Example 6
The point which used the process film (the product name "PLS100T161" by Lintec Co., Ltd.) which has the hardened layer of a silicone resin composition on one surface of the 100-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
比較例１
　工程フィルムとして、基材フィルムである厚さ３８μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＤＳ３８２１６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 1
The point which used the process film (the product name "PDS382160" by the Lintec Co., Ltd. product) which has the hardened layer of a silicone resin composition on one surface of the 38-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
比較例２
　工程フィルムとして、基材フィルムである厚さ２５μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＤＳ２５２１６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 2
The point which used the process film (the product name "PDS252160" by Lintec Corporation) which has the hardened layer of a silicone resin composition on one surface of the 25-micrometer-thick polyethylene terephthalate film which is a base film as a process film. Except for the above, a separator with a process film was produced in the same manner as in Example 1.
比較例３
　工程フィルムとして、基材フィルムである厚さ３１μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＤ３１２０６０」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 3
The point which used the process film (the product name "PLD31060" by Lintec Corporation) which has the hardened layer of a silicone resin composition on one side of the 31-micrometer-thick polyethylene terephthalate film which is a base film as a process film Except for the above, a separator with a process film was produced in the same manner as in Example 1.
比較例４
　工程フィルムとして、基材フィルムである厚さ３１μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＰＬＳ３１Ｔ１６１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 4
The point which used the process film (the product name "PLS31T161" by Lintec Corporation) which has the hardened layer of a silicone resin composition on one side of the 31-micrometer-thick polyethylene terephthalate film which is a base film as a process film Except for the above, a separator with a process film was produced in the same manner as in Example 1.
比較例５
　工程フィルムとして、基材フィルムである厚さ３８μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＮＦ ＳＰ－ＰＥＴ３８１０３１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 5
As a process film, a process film (trade name “NF SP-PET 381031” manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 38 μm-thick polyethylene terephthalate film as a base film is used. A separator with a process film was produced in the same manner as in Example 1 except for the points used.
比較例６
　工程フィルムとして、基材フィルムである厚さ２５μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＮＦ ＳＰ－ＰＥＴ２５１０３１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 6
As a process film, a process film (trade name “NF SP-PET 251031” manufactured by Lintec Corporation) having a cured layer of a silicone resin composition on one surface of a 25 μm-thick polyethylene terephthalate film as a base film is used. A separator with a process film was produced in the same manner as in Example 1 except for the points used.
比較例７
　工程フィルムとして、基材フィルムである厚さ３８μｍのポリエチレンテレフタレートフィルムの一方の面の上にシリコーン樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＮＦ ＳＰ－ＰＥＴ３８Ｔ１０３－１」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 7
As a process film, a process film having a cured layer of a silicone resin composition on one side of a 38 μm-thick polyethylene terephthalate film as a base film (product name “NF SP-PET38T103-1”, manufactured by Lintec Corporation) ) Was used in the same manner as in Example 1 except that a separator with a process film was produced.
比較例８
　工程フィルムとして、基材フィルムである厚さ５０μｍのポリエチレンテレフタレートフィルムの一方の面の上にアルキド樹脂組成物の硬化層を有する工程フィルム（リンテック株式会社製、商品名「ＳＰ－ＰＦＳ５０ＡＬ－５」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 8
As a process film, a process film having a cured layer of an alkyd resin composition on one surface of a 50 μm thick polyethylene terephthalate film as a base film (trade name “SP-PFS50AL-5”, manufactured by Lintec Corporation) A separator with a process film was produced in the same manner as in Example 1 except that was used.
比較例９
　工程フィルムとして、硬化層を有さない厚さ３８μｍのポリエチレンテレフタレートフィルム（三菱樹脂株式会社製、商品名「ＰＥＴ３８Ｔ－１００」）を用いた点以外は、実施例１と同様にして工程フィルム付きセパレータを製造した。 Comparative Example 9
Separator with process film as in Example 1 except that a polyethylene terephthalate film (trade name “PET38T-100”, manufactured by Mitsubishi Plastics, Inc.) having a thickness of 38 μm without a cured layer was used as the process film. Manufactured.
上記各実施例、比較例の工程フィルム、及び工程フィルム付きセパレータを上記の測定方法により評価した。その結果を表１に示す。
Figure JPOXMLDOC01-appb-T000001
 The process film of each said Example and a comparative example, and the separator with a process film were evaluated by said measuring method. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
　表１から分かるように、実施例１～４に係る工程フィルム付きセパレータは、硬化層が良好な弾性率を有し、かつ工程フィルムが好適な剛軟度を有していたため、工程フィルムから剥離する際多孔質膜に形状変化や破損が生じず、また、工程フィルム付きセパレータに生じるカールの発生量を抑えることができた。また、実施例５、６では、硬化層の弾性率が若干低く、工程フィルムの高速での離型性は良好ではなかったものの、低速での離型性が良好であり多孔質膜を破損や形状変化をすることなく剥離することができ、また、剛軟度が良好であったためカールの発生量も抑えることできた。
　一方で、比較例１～９に係る工程フィルム付きセパレータは、工程フィルムの剛軟度が低かったため、多孔質膜に大きなカールが生じ、実施例１～６に比べ性能が劣るものであった。また、比較例５～９は、硬化層の弾性率が低く、或いはシリコーン硬化層を有していないため、離型性が悪く、剥離時に多孔質膜に破損が生じた。 As can be seen from Table 1, the separators with process films according to Examples 1 to 4 were peeled off from the process film because the cured layer had a good elastic modulus and the process film had a suitable bending resistance. In this case, the porous film was not changed in shape or damaged, and the amount of curling generated in the separator with the process film could be suppressed. Further, in Examples 5 and 6, although the elastic modulus of the cured layer was slightly low and the releasability at high speed of the process film was not good, the releasability at low speed was good and the porous film was damaged. The film could be peeled without changing its shape, and the amount of curling could be suppressed because of its good bending resistance.
On the other hand, the separators with a process film according to Comparative Examples 1 to 9 had poor curling softness of the process film, so that a large curl was generated in the porous film, and the performance was inferior to those of Examples 1 to 6. In Comparative Examples 5 to 9, since the elastic modulus of the cured layer was low or the cured silicone layer was not provided, the releasability was poor, and the porous film was damaged during peeling.

Claims (12)

  1. 　シリコーン樹脂組成物の硬化層を有する工程フィルムと、前記硬化層の上に設けられ、かつ微粒子（Ａ）及び樹脂バインダ（Ｂ）を含有する多孔質膜からなるリチウムイオン二次電池用セパレータとを備え、
    　前記硬化層の弾性率が０．１５ＧＰａ以上であり、かつ前記工程フィルムのガーレ法による剛軟度が０．３ｍＮ以上である工程フィルム付きリチウムイオン二次電池用セパレータ。     A process film having a cured layer of a silicone resin composition, and a separator for a lithium ion secondary battery comprising a porous film provided on the cured layer and containing fine particles (A) and a resin binder (B) Prepared,
    The separator for lithium ion secondary batteries with a process film whose elastic modulus of the said hardened layer is 0.15 GPa or more, and the bending resistance of the said process film by the Gurley method is 0.3 mN or more.
  2. 　前記多孔質膜が、微粒子（Ａ）、樹脂バインダ（Ｂ）及び溶媒（Ｃ）を含有する多孔質膜形成用組成物を、前記硬化層上に塗布し、乾燥することにより形成したものである請求項１に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The porous film is formed by applying a porous film forming composition containing fine particles (A), a resin binder (B) and a solvent (C) on the cured layer and drying. The separator for lithium ion secondary batteries with a process film of Claim 1.
  3. 　前記工程フィルムの硬化層の前記溶媒（Ｃ）に対する接触角が５５°以上７５°以下である請求項２に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to claim 2, wherein a contact angle of the cured layer of the process film with respect to the solvent (C) is 55 ° or more and 75 ° or less.
  4. 　前記工程フィルムの硬化層表面の算術平均粗さが１５．０ｎｍ以下である請求項１～３のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 3, wherein the arithmetic average roughness of the cured layer surface of the process film is 15.0 nm or less.
  5. 　前記工程フィルムの硬化層表面の最大断面高さが、２００．０ｎｍ以下である請求項１～４のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 4, wherein the maximum cross-sectional height of the cured layer surface of the process film is 200.0 nm or less.
  6. 　微粒子（Ａ）がベーマイトである請求項１～５のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 5, wherein the fine particles (A) are boehmite.
  7. 　微粒子（Ａ）の平均粒径が０．１μｍ以上５μｍ以下である請求項１～６のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 6, wherein the fine particles (A) have an average particle size of 0.1 to 5 µm.
  8. 　バインダ（Ｂ）の重量平均分子量が１００，０００以上２，０００，０００以下である請求項１～７のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 7, wherein the binder (B) has a weight average molecular weight of 100,000 or more and 2,000,000 or less.
  9. 　多孔質膜中の微粒子（Ａ）が４０体積％以上８５体積％以下である請求項１～８のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 8, wherein the fine particles (A) in the porous film are 40 vol% or more and 85 vol% or less.
  10. 　樹脂バインダ（Ｂ）が、フッ素系樹脂バインダである請求項１～９のいずれかに記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to any one of claims 1 to 9, wherein the resin binder (B) is a fluorine resin binder.
  11. 　前記フッ素系樹脂バインダが、ポリフッ化ビニリデンである請求項１０に記載の工程フィルム付きリチウムイオン二次電池用セパレータ。 The separator for a lithium ion secondary battery with a process film according to claim 10, wherein the fluororesin binder is polyvinylidene fluoride.
  12. 　微粒子（Ａ）と、樹脂バインダ（Ｂ）とを含有する多孔質膜形成用組成物を、シリコーン樹脂組成物の硬化層を有する工程フィルムの前記硬化層上に塗布し、乾燥して工程フィルム付きリチウムイオン二次電池用セパレータを得る工程フィルム付きリチウムイオン二次電池用セパレータの製造方法であって、
    　前記硬化層の弾性率が０．１５ＧＰａ以上であり、かつ前記工程フィルムのガーレ法による剛軟度が０．３ｍＮ以上である工程フィルム付きリチウムイオン二次電池用セパレータの製造方法。     A porous film forming composition containing fine particles (A) and a resin binder (B) is applied onto the cured layer of a process film having a cured layer of a silicone resin composition, and dried to provide a process film. A process for obtaining a separator for a lithium ion secondary battery is a method for producing a separator for a lithium ion secondary battery with a film,
    The manufacturing method of the separator for lithium ion secondary batteries with a process film whose elastic modulus of the said hardened layer is 0.15 GPa or more, and the bending resistance by the Gurley method of the said process film is 0.3 mN or more.
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WO2024192582A1 (en) * 2023-03-17 2024-09-26 宁德时代新能源科技股份有限公司 Separator, secondary battery, and electrical apparatus

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