CN107492625A - Battery separator and its manufacture method - Google Patents

Battery separator and its manufacture method Download PDF

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Publication number
CN107492625A
CN107492625A CN201710203782.2A CN201710203782A CN107492625A CN 107492625 A CN107492625 A CN 107492625A CN 201710203782 A CN201710203782 A CN 201710203782A CN 107492625 A CN107492625 A CN 107492625A
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CN
China
Prior art keywords
copolymer
battery separator
vinylidene fluoride
acrylic resin
polymer
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Granted
Application number
CN201710203782.2A
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Chinese (zh)
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CN107492625B (en
Inventor
辻本润
水野直树
梶田笃史
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Toray Industries Inc
Toray Battery Separator Film Co Ltd
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Toray Industries Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
    • C08J5/2218—Synthetic macromolecular compounds
    • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
    • C08J5/2237—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds containing fluorine
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • 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
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—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
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/26—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers modified by chemical after-treatment
    • C08J2323/28—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers modified by chemical after-treatment by reaction with halogens or halogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/16—Homopolymers or copolymers of vinylidene fluoride
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Composite Materials (AREA)
  • Cell Separators (AREA)

Abstract

The purpose of the present inventor etc. is to provide a kind of battery separator and its manufacture method, the popularization of battery (especially laminated type battery) maximization of the battery separator for that may develop in the future is prepared, bending strength when can take into account the drying as problem, bending strength when peeling force, moistening when drying.A kind of battery separator, it has micro-porous film and is at least located at the porous layer of micro-porous film one side, the porous layer contains vinylidene fluoride hexafluoropropylene copolymer (A), polymer (B) and acrylic resin containing vinylidene fluoride units, hexafluoropropene unit of the vinylidene fluoride hexafluoropropylene copolymer (A) containing hydrophilic group and 0.3 molar percentage to 3 molar percentages, the fusing point of the polymer (B) containing vinylidene fluoride units is less than more than 60 DEG C 145 DEG C, and weight average molecular weight is less than more than 100,000 75 ten thousand.

Description

Battery separator and its manufacture method
Technical field
The present invention relates to a kind of battery separator and its manufacture method.
Background technology
Rechargeable nonaqueous electrolytic battery especially lithium rechargeable battery is applied to mobile phone and personal digital assistant device etc. Miniaturized electronics are simultaneously widely available, while develop cylinder battery, prismatic battery, laminated type battery etc..Generally, these Battery has and will carry out the electrode body (laminate electrode body) of lamination to positive electrode and negative electrode across barrier film and be wound into swirling Electrode body (rolled electrode bodies) and nonaqueous electrolytic solution store the structure into external packing body.
Conventional rechargeable nonaqueous electrolytic battery mainly uses the micro-porous film being made up of vistanex with barrier film, in electricity Current flowing is suppressed by the pore of inaccessible barrier film during the abnormal heating of pond, prevented on fire etc..
In recent years, carried out setting porous layer to improve tasting for battery behavior by the single or double in micro-porous film Examination.For example, there is the barrier film for setting porous layer, the porous layer contain for the fluororesin that assigns the functions such as electrode adhesion and Acrylic resin (patent document 1 of prior art literature to patent document 8).If in addition, added into porous layer inorganic Particle, then when accident etc. occurs, even if battery is pierced through by sharp keen metal, suddenly-applied short circuit and hot occurs, it is also possible to prevent The melting of barrier film is shunk and suppresses the expansion of interelectrode short-circuiting percentage.
A kind of electrode body is recorded in patent document 1, the electrode body has positive pole, negative pole, by polypropylene, polyethylene/poly- The three-layer membrane and configure among these electrodes and barrier film and by polyvinylidene fluoride and alumina powder structure that propylene is formed Into adhesive resin layer.
A kind of organic barrier film with perforated membrane is recorded in the embodiment 1 of patent document 2, the organic barrier film with perforated membrane Obtain in the following manner：NMP (the N- of first polymer (polyvinylidene fluroide homopolymer) will be contained methylpyrrolidone；1-METHYLPYRROLIDONE) solution and containing second polymer (containing acrylonitrile monemer, from 1, The polymer of the monomer of 3- butadiene, methacrylic acid monomer and Butyl Acrylate Monomer) nmp solution pass through PRIMARY STIRRING The nmp solution of modulating adhesive after device (primary mixer) stirring, then by the nmp solution and aluminium oxide particles after modulation Mixing, the slurry modulated after disperseing are applied on polypropylene barrier film.
Recorded in the embodiment of patent document 3 a kind of to being sandwiched between thin slice (the insulating properties bonding containing inorganic fine particles Layer) positive pole and negative pole carry out thermocompression bonding electrode body, should thin slice (insulating properties adhesive layer) containing inorganic fine particles by with Under type obtains：Addition is dissolved with common by vinylidene fluoride-hexafluoropropene in the nmp solution for being dispersed with spherical alumina powder The nmp solution for the compounding ingredient that polymers (VdF-HFP copolymers) and polyethyl methacrylate are formed, is mixed by ball mill Afterwards, the slurry of preparation is applied to base material PET (polyethylene terephthalate；PET) it is thin Obtained on film and after being dried.
A kind of barrier film is recorded in the embodiment 1 of patent document 4, the barrier film obtains in the following manner：VdF-HFP is total to Polymers and cyanoethyl pullulan are added in acetone, then add barium titanate powder, are obtained after being disperseed by ball mill Slurry be applied on polyethylene porous film and obtain.
A kind of barrier film is recorded in the embodiment 1 of patent document 5, the barrier film is by VdF-HFP copolymers (HFP units 0.6 Molar percentage (mol%)) and VdF-HFP copolymers (weight average molecular weight 470,000, the molar percentage of HFP units 4.8) be dissolved to In dimethyl acetamide and tripropylene glycol solution, porous layer is formed after being then applied to microporous polyethylene film.
Recorded a kind of barrier film in the embodiment 1 of patent document 6, the barrier film be by PvdF (weight average molecular weight 500,000) and VdF-HFP copolymers (weight average molecular weight 400,000, the molar percentage of HFP units 5) are dissolved to dimethyl acetamide and tripropylene glycol In solution, porous layer is formed after being then applied to microporous polyethylene film.
Recorded a kind of barrier film in the embodiment 1 of patent document 7, the barrier film be by PvdF (weight average molecular weight 700,000) and VdF-HFP copolymers (weight average molecular weight 470,000, the molar percentage of HFP units 4.8) are dissolved to dimethyl acetamide and 3 the third two In alcoholic solution, porous layer is formed after being then applied to microporous polyethylene film.
Recorded a kind of barrier film in the embodiment 1 of patent document 8, the barrier film be by PvdF (weight average molecular weight 350,000) and VdF-HFP polymer (weight average molecular weight 270,000, the molar percentage of HFP polymer 4.8) is dissolved to dimethyl acetamide and 3 third In glycol solution, porous layer is formed after being then applied to microporous polyethylene film.
The layer configured between barrier film and electrode and barrier film disclosed in patent document 1 to 8 is comprising poly- inclined difluoro second Vinyl resin.
[prior art literature]
[patent document]
Patent document 1：Japan Patent table 1999-036981 publications again.
Patent document 2：Japanese Patent Laid-Open 2013-206846 publications.
Patent document 3：Japanese Patent Laid-Open 2013-122009 publications.
Patent document 4：Japanese Patent Laid 2013-519206 publications.
Patent document 5：No. 5282179 publications of Japanese Patent No..
Patent document 6：No. 5282180 publications of Japanese Patent No..
Patent document 7：No. 5282181 publications of Japanese Patent No..
Patent document 8：No. 5342088 publications of Japanese Patent No..
The content of the invention
[inventing problem to be solved]
In recent years, expect by rechargeable nonaqueous electrolytic battery be applied to large flat equipment, hay mover, electric bicycle, The large-scale purposes such as electric automobile, hybrid vehicle, spitkit, at the same time, it is contemplated that will be popularized to large-sized battery.
Rolled electrode bodies are sandwiched between barrier film in positive electrode and negative electrode, are wound while applying tension force to each component And it is made.Now, it is hardly flexible for tension force that positive electrode and the negative electrode of metal current collector are applied to, and barrier film is in certain journey It is wound while stretching on degree along operating direction.After the coiling body is placed into a period of time, membrane portions are slowly punctured into The original length.Its result causes, and produces the power of parallel direction in the interface of electrode and barrier film, rolled electrode bodies are (especially Be wound as the electrode body of flat) easily produce flexure and it is crooked.Moreover, with the maximization of battery, the width of barrier film broadens, Length, so as to cause these problems more obvious, yield rate during worrying production can reduce.It is envisioned that it is Suppress rolled electrode bodies and produce flexure and crooked, it is necessary to make the cohesive of barrier film and electrode more stronger than now.In this specification, On the cohesive, bending strength is used as index during the drying that will be obtained by assay method described later.
In addition, when carrying electrode body, if each component is not in the state fully bonded, electrode and barrier film can be peeled off, no It can be carried with higher yield rate.Due to the maximization of battery, bonding sex chromosome mosaicism during carrying is more obvious, worrying Yield rate can reduce.Therefore, it is contemplated that barrier film needs to have peeling force when being difficult to from stripping electrode, high dry.
Moreover, especially in laminated type battery, with applying stressed prismatic, cylinder battery phase by external packing body Than, it is difficult to apply pressure, electrode is as discharge and recharge can produce expansion and shrink, so as to cause barrier film and electrode interface face easily to be sent out First portion dissociates.Its result is to cause cell expansion, the resistance increase of inside battery, cycle performance to reduce.It is therefore desirable to every Film has certain cohesive with the electrode in the battery after injection electrolyte.In this specification, on the cohesive, it will pass through Bending strength is as index during the moistening that assay method described later obtains.When the intensity is larger, it is contemplated that improve the spy of battery Property, such as suppress the expansion of the battery after repeated charge.
In conventional technology, when peeling force, moistening there is containing pass in bending strength when bending strength, drying when drying System, will meet that all physical characteristics are extremely difficult.It is an object of the present invention to provide a kind of battery separator, the battery is used The popularization of battery (especially laminated type battery) maximization of the barrier film for that may develop in the future is prepared, and is bent when can meet to dry Intensity, dry when peeling force, moistening when bending strength condition.
In addition, bending strength is represented in the state of barrier film contains electrolyte during moistening described in this specification, barrier film With the cohesive of electrode.Bending strength and peeling force when drying are represented in the not substantive state containing electrolyte of barrier film when drying Under, for the cohesive of barrier film and the interface of electrode.In addition, essence containing refer to electrolyte in barrier film for 500ppm with Under.
[technological means for solving problem]
In order to solve the above problems, battery separator of the invention and its manufacture method have following composition.
(1) a kind of battery separator, it is characterised in that there is micro-porous film and be at least located at the Porous of micro-porous film one side Layer, the porous layer contain vinylidene difluoride-hexafluoropropylene copolymer (A), the polymer (B) containing vinylidene fluoride units with And acrylic resin, the vinylidene difluoride-hexafluoropropylene copolymer (A) is containing hydrophilic group and 0.3 molar percentage to 3 moles The hexafluoropropene unit of percentage, the fusing point of the polymer (B) containing vinylidene fluoride units for more than 60 DEG C 145 DEG C with Under, weight average molecular weight is less than more than 100,000 75 ten thousand.
(2) in battery separator of the invention, the weight average molecular weight of preferably vinylidene difluoride-hexafluoropropylene copolymer (A) is more than 750000 and for less than 2,000,000.
(3) in battery separator of the invention, preferably porous layer contains particle.
(4) in battery separator of the invention, the content of preferably vinylidene difluoride-hexafluoropropylene copolymer (A) accounts for inclined difluoro second More than 15 percentage by weights of the gross weight of alkene-hexafluoropropylene copolymer (A) and polymer (B) containing vinylidene fluoride units 85 Below percentage by weight, the content of acrylic resin accounts for vinylidene difluoride-hexafluoropropylene copolymer (A), list containing vinylidene fluoride More than the polymer (B) of member and 4 percentage by weights of the gross weight of acrylic resin below 40 percentage by weights.
(5) in battery separator of the invention, preferred acrylic resins are (methyl) acrylate and the monomer with cyano group Copolymer.
(6) in battery separator of the invention, preferred acrylic resins are the copolymer containing butyl acrylate.
(7) in battery separator of the invention, preferred acrylic resins are the copolymer of butyl acrylate and acrylonitrile.
(8) in battery separator of the invention, the content of the butyl acrylate in preferred acrylic resins is 50 molar percentages To 75 molar percentages.
(9) in battery separator of the invention, the content of the preferably hydrophilic group of vinylidene difluoride-hexafluoropropylene copolymer (A) is 0.1 molar percentage to 5 molar percentages.
(10) in battery separator of the invention, bending strength be more than 4N when preferably moistening, when drying bending strength for 5N with On, and peeling force is 8N/m when drying.
(11) in battery separator of the invention, the content of preferred particle accounts for more than 50 percentage by weights of porous layer gross weight Below 90 percentage by weights.
(12) in battery separator of the invention, preferred particle is included in the group being made up of aluminum oxide, titanium oxide, boehmite At least one.
(13) in battery separator of the invention, preferably the one side thickness of porous layer is 0.5 μm to 3 μm.
(14) in battery separator of the invention, preferably micro-porous film is polyolefin micro porous polyolefin membrane.
In order to solve above-mentioned problem, the manufacture method of polyolefin micro porous polyolefin membrane of the invention has following structure.
(15) a kind of manufacture method of battery separator, it is characterised in that the battery for being (1) into (14) described in any one with every The manufacture method of film, successively including following process.
(1) vinylidene difluoride-hexafluoropropylene copolymer (A) and polymer (B) containing vinylidene fluoride units are dissolved to solvent The process for obtaining fluorine-type resin solution afterwards.
(2) acrylic resin is dissolved to the acrylic resin soln obtained after solvent to be added in fluorine-type resin solution, mixing The process for obtaining coating fluid afterwards.
(3) will be immersed in after coating solution to micro-porous film in solidification liquid, and the process cleaned, dried, wherein, it is described Hexafluoropropene of the vinylidene difluoride-hexafluoropropylene copolymer (A) containing hydrophilic group and 0.3 molar percentage to 3 molar percentages Unit, the fusing point of the polymer (B) containing vinylidene fluoride units is less than more than 60 DEG C 145 DEG C, weight average molecular weight 10 Less than more than ten thousand 75 ten thousand, the acrylic resin contains butyl acrylate.
[The effect of invention]
According to the present invention, it is possible to provide a kind of battery separator, the battery separator are large-scale for the battery that may develop in the future The popularization of change is prepared, bending strength when can meet to dry, when drying when peeling force, moistening bending strength condition.
Brief description of the drawings
Fig. 1 is the front cross-sectional view of bending strength test when schematically showing moistening.
Fig. 2 is the front cross-sectional view of bending strength test when schematically showing dry.
Embodiment
Hereinafter, the summary of the battery separator at least with micro-porous film and porous layer of the present invention is illustrated, Certain present invention is not limited to the typical example.
1. micro-porous film
First, the micro-porous film of the present invention is illustrated.
In the present invention, micro-porous film refers to the film in the internal space for having and linking.It is not particularly limited for micro-porous film, can Use non-woven fabrics and micro-porous film.Hereinafter, the resin for forming micro-porous film is described in detail for the situation of vistanex, But it is not limited to this.
[1] vistanex
The vistanex of polyolefin micro porous polyolefin membrane is formed using polyvinyl resin and acrylic resin as main component.By polyolefin When the total quality of resin is set to 100 mass percent, the content of polyvinyl resin is preferably more than 70 mass percents, more excellent Elect as more than 90 mass percents, more preferably 100 mass percents.
As vistanex, it can enumerate and polymerize ethene, propylene, 1- butylene, 4-methyl-1-pentene, 1- hexenes etc. Homopolymer, 2 grades of polymer, copolymer or these mixture etc..Can be in the range of the effect of the present invention not be damaged, poly- In olefin resin, the various additives such as antioxidant, inorganic filler are added as needed on.
[2] manufacture method of polyolefin micro porous polyolefin membrane
As the manufacture method of polyolefin micro porous polyolefin membrane, as long as the polyolefin micro porous polyolefin membrane with required characteristic can be manufactured, then It is not particularly limited, known method can be used, such as Japanese Patent No. 2132327 and Japan Patent can be used The method of the records such as the specification of No. 3347835, International Publication 2006/137540.Specifically, following work is preferably included Sequence (1) to (5).
(1) melting mixing is carried out with solvent to the vistanex and film forming, the process for preparing polyolefin solution.
(2) polyolefin solution is extruded, the process for being allowed to cool and forming gluey piece.
(3) the 1st stretching process stretched to the gluey piece.
(4) process that film forming solvent is removed from the gluey piece after the stretching.
(5) process of the sheet drying after the removing film forming solvent is made.
Hereinafter, each operation is illustrated respectively.
(1) preparation section of polyolefin solution
After adding appropriate film forming solvent respectively in vistanex, melting mixing is carried out, prepares polyolefin solution.As Melting mixing method, it can use and remember in such as No. 3347835 specifications of Japanese Patent No. 2132327 and Japanese Patent No. The method using double screw extruder of load.Due to melting mixing method it is widely known that description will be omitted.
In polyolefin solution, vistanex is not particularly limited with film forming with the mixing ratio of solvent, but preferably phase For the mass parts of vistanex 20 to 30 mass parts, film forming solvent is 70 mass parts to 80 mass parts.If vistanex Ratio within the above range, then in extruded polyolefin solution, can prevent the expansion at mould outlet and inside contract, and be extruded into The mouldability and self-sustainance of type body (gluey formed body) are good.
(2) formation process of gluey piece
Polyolefin solution is delivered to mould from extruder, is extruded into sheet.By more parts of polyolefin solutions of identical or different composition 1 mould is delivered to from extruder, lamination is stratiform there, can also be extruded into sheet.
Extrusion method can be any of flat-die method and blowing.Extrusion temperature is preferably 140 DEG C to 250 DEG C, is squeezed It is preferably 0.2m/ minutes to 15m/ minutes to go out speed.By adjusting the respective extrusion capacity of polyolefin solution, thickness can be adjusted. As extrusion method, the side disclosed in such as Japanese Patent No. 2132327 and Japanese Patent No. 3347835 can be used Method.
By the way that the extrusion molding obtained body is cooled down, gluey piece is formed., can be with as the forming method of gluey piece Use the method disclosed in such as No. 3347835 publications of No. 2132327 publications of Japanese Patent No. and Japanese Patent No..It is preferred that with More than 50 DEG C/min of speed is cooled at least gelatinization temperature.It is preferred that implement cooling below 25 DEG C.By cooling, can make Fixed by film forming with the microfacies of the separated polyolefin of solvent.If cooling velocity is within the above range, crystallization degree can be protected Hold in appropriate scope, form the gluey piece for being adapted to stretching.As cooling means, the refrigerant such as usable and cold wind, cooling water The method of contact, the method contacted with chill roll etc., are preferably contacted with the roller cooled down using refrigerant and are allowed to cool.
(3) the 1st stretching process
Then, the gluey piece obtained to the stretching of at least single shaft direction.Because gluey piece includes film forming solvent, therefore can be equal Stretch evenly.Gluey piece preferably after the heating, by the combination of tentering method, roll-in method, blowing or these methods, with rule Determine multiplying power to be stretched.Stretching can be uniaxial tension or biaxial stretch-formed but preferably biaxial stretch-formed.It is biaxial stretch-formed In the case of, can be that simultaneously biaxial drawing, gradually stretching and multistage stretching (such as simultaneously biaxial drawing and gradually stretch Any of combination).
Stretching ratio (area stretch multiplying power) in this process is preferably more than 9 times, more preferably more than 16 times, especially excellent Elect more than 25 times as.In addition, the stretching ratio of operating direction (MD) and width (TD) can it is identical each other can also be different. In addition, the stretching ratio in this process refers to, on the basis of the micro-porous film before this process, for micro- before subsequent processing The area stretch multiplying power of perforated membrane.
The draft temperature of this process is preferably in the scope of the crystal dispersion temperature (Tcd) to Tcd+30 DEG C of vistanex It is interior, more preferably in the range of+5 DEG C of crystal dispersion temperature (Tcd) to+28 DEG C of crystal dispersion temperature (Tcd), particularly preferably exist In the range of Tcd+10 DEG C to Tcd+26 DEG C.For example, during polyethylene, preferably draft temperature is 90 DEG C to 140 DEG C, more preferably 100 DEG C to 130 DEG C.Crystal dispersion temperature (Tcd) utilizes ASTM (American Society for Testing Materials；ASTM standard) D4065 dynamic viscoelastic temperature characterisitic measure obtain.
According to above-mentioned stretching, cracking can be produced between polyethylene sheets, polyethylene mutually realizes miniaturization, forms numerous fibrils Dimension.Fibrillation forms the three-dimensional mesh configuration irregularly connected.Using stretching, mechanical strength can be improved, while expands pore, When being stretched in the proper condition, insertion aperture can be controlled, further can also be had in relatively thin thickness higher Void content.
Can also be according to required physical property, design temperature is distributed and stretched on film thickness direction, thus can obtain machinery The more excellent micro-porous film of intensity.The detailed content of this method is recorded in Japanese Patent No. 3347854.
(4) removing of film forming solvent
Using cleaning solvent, (cleaning) film forming solvent is removed.Because polyolefin phase is separated with film forming with solvent, so removing After film forming solvent, following multiple aperture plasma membranes can be obtained, the fibrillation structure that the multiple aperture plasma membrane is constructed by forming small three-dimensional mesh Into, and with the three-dimensional hole (space) irregularly connected.Cleaning solvent and the side that film forming solvent is removed using cleaning solvent Method is it is widely known that description will be omitted.Such as No. 2132327 specifications of Japanese Patent No. and Japanese Patent Laid-Open can be used Method disclosed in 2002-256099 publications.
(5) dry
Using heat drying method or aeration drying, film forming will be removed and be dried with the micro-porous film after solvent.Drying temperature is preferred Vistanex crystal dispersion temperature (Tcd) below, it is particularly preferably lower than Tcd more than 5 DEG C.Micro-porous film is set to 100 During mass percent (dry weight), it is below 5 mass percents preferably to dry to remaining cleaning solvent, is more preferably dried to 3 Below mass percent.If remaining cleaning solvent is within the above range, the stretching process and heat of follow-up micro-porous film are carried out During treatment process, the void content of micro-porous film is able to maintain that, suppresses the deterioration of permeability.
2. porous layer
In the present invention, porous layer contains vinylidene fluoride-hexafluoropropene (VdF-HFP) copolymer (A) and containing vinylidene fluoride The polymer (B) and acrylic resin of unit.Each resin is illustrated below.
[1] vinylidene fluoride-hexafluoropropene (VdF-HFP) copolymer (A)
Vinylidene fluoride-hexafluoropropene (VdF-HFP) copolymer (A) used in the present invention contains hydrophilic group, and is rubbed containing 0.3 Your percentage to 3 molar percentages hexafluoropropene.Copolymer (A) is high for the compatibility of nonaqueous electrolytic solution, and chemistry, physics are steady Qualitative height, and with bending strength when moistening, therefore even if at high temperature in use, also can fully maintain and electrolyte Compatibility.
Vinylidene difluoride-hexafluoropropylene copolymer (A) has hydrophilic group, so as to the active matter with being present in electrode surface Adhesive ingredients good bond in matter and electrode.Caused by speculating this bonding force and being hydrogen bond.As hydrophilic group, can include Hydroxyl, carboxylic acid group, sulfonic group and their salt etc..Particularly preferred carboxylic acid group, carboxylate.
When importing hydrophilic group into vinylidene fluoride, such as following methods can be enumerated：In synthesis vinylidene fluoride-hexafluoro During propylene copolymer (A), by making maleic anhydride, maleic acid, maleate, monomethyl maleate etc. that there is the monomer of hydrophilic group The method for being copolymerized and being directed into main chain, and by grafting be turned to side chain import method.Hydrophilic group degree of modification can pass through FT- IR(Fouier Transform Infrared Spectroscopy；Fourier transform infrared spectrometry), NMR (nuclear magnetic resonance；Nuclear magnetic resonance), quantitative titration etc. is measured.For example, during carboxylic acid group, FT-IR can be used, will Homopolymer is calculated as benchmark according to the absorption intensity ratio of C-H stretching vibrations and the C=O stretching vibrations of carboxyl.
In vinylidene difluoride-hexafluoropropylene copolymer (A) lower limit of hydrophile content be preferably 0.1 molar percentage with On, more preferably more than 0.3 molar percentage, higher limit is preferably more preferably 4 molar percentages below 5 molar percentages Below.When the content of hydrophilic group is more than 5 molar percentage, polymer crystallinity is too low, is uprised for the swellbility of electrolyte, wet Bending strength is deteriorated during profit.In addition, when containing particle in porous layer, by the way that the content of hydrophilic group is located at into above-mentioned preferred scope It is interior, particle can be suppressed and come off.
The lower limit of hexafluoropropene content is preferably 0.3 molar percentage in vinylidene difluoride-hexafluoropropylene copolymer (A) More than, more preferably more than 0.5 molar percentage, higher limit is preferably more preferably 2.5 mole hundred below 3 molar percentages Divide than following.If the content of hexafluoropropene uprises less than 0.3 molar percentage, polymer crystallinity, for the molten of electrolyte Expansibility step-down, bending strength during therefore, it is difficult to fully obtain moistening.It is if molten for electrolyte in addition, more than 3 molar percentages It is swollen excessively, bending strength reduces during moistening.
The content of vinylidene difluoride-hexafluoropropylene copolymer (A) relative to copolymer (A) and polymer (B) gross weight, Lower limit is preferably more than 15 percentage by weights, and more preferably more than 25 percentage by weights, higher limit is preferably 85 weight percents Than following, more preferably below 25 percentage by weights.
The lower limit of the weight average molecular weight of vinylidene difluoride-hexafluoropropylene copolymer (A) be more than 750,000, preferably 900,000 with On, higher limit is preferably less than 2,000,000, and more preferably less than 1,500,000.By the way that the weight average molecular weight of copolymer (A) is located at State in preferred scope, copolymer (A) is dissolved to the time of solvent would not become extremely very long, can improve production efficiency.This Outside, appropriate gel strength can be maintained when being swelled in the electrolytic solution, bending strength when improving moistening.It is in addition, heretofore described Weight average molecular weight be by gel permeation chromatography calculate polystyrene scaled value.
Vinylidene difluoride-hexafluoropropylene copolymer (A) can be obtained by well-known polymerization.As well-known Polymerization, such as the method illustrated can be enumerated in Japanese Patent Laid-Open 11-130821.That is, by ion exchange water, Malaysia Sour mono-methyl, vinylidene fluoride and hexafluoropropene are put into autoclave, suspension polymerisation are carried out, afterwards, by polymer syrup After material is dehydrated, cleaned, make its drying, the method for obtaining polymer powder.Now, methylcellulose conduct can suitably be used Suspending agent, radical initiator is used as using di-isopropyl peroxydicarbonate etc..
Vinylidene difluoride-hexafluoropropylene copolymer (A) is not in the range of characteristic is damaged, or with hydrophilic group Monomer beyond the copolymer that further polymerize of other monomers.As the other monomers beyond the monomer with hydrophilic group, example Tetrafluoroethene, CTFE, trichloro ethylene, ethylene fluoride monomer can such as be enumerated.
[2] polymer containing vinylidene fluoride units (B)
The fusing point of the polymer (B) containing vinylidene fluoride units used in the present invention is less than more than 60 DEG C 145 DEG C, is divided equally again Son amount is less than more than 100,000 75 ten thousand, and high for the compatibility of nonaqueous electrolytic solution, chemistry, physical stability are high, can obtain drying When bending strength and dry when peeling force.Mechanism on this is still not clear, but inventors are speculated it can be found that drying When bending strength and dry when peeling force heating and pressurized conditions under, polymer (B) carries mobility, into the porous of electrode Turn into fixator after matter layer, thus, there is firm cohesive between porous layer and electrode.Polymer (B) helps to realize Bending strength and peeling force when drying when drying, and help to prevent bending, being crooked for rolled electrode bodies and laminate electrode body, Carrying can be improved.In addition, the polymer (B) containing vinylidene fluoride units is and vinylidene difluoride-hexafluoropropylene copolymer (A) Different resins.
The lower limit of the fusing point of polymer (B) containing vinylidene fluoride units is preferably more than 60 DEG C, more preferably 80 DEG C More than, higher limit is preferably less than 145 DEG C, more preferably less than 140 DEG C.In addition, fusing point described here refers to pass through differential The peak temperature of endothermic peak during the heating of scanning calorimetry (DSC) measure.
Polymer (B) containing vinylidene fluoride units is by the copolymerization with polyvinylidene fluoride or vinylidene fluoride units The resin that thing is formed.Polymer (B) can be by obtaining with copolymer (A) identical suspension polymerization etc..By controlling by inclined two The crystallinity at the position that PVF unit is formed, it can adjust the fusing point of polymer (B).For example, contain inclined difluoro in polymer (B) During monomer beyond ethylene unit, by controlling the ratio of vinylidene fluoride units, fusing point can adjust.Vinylidene fluoride units with Outer monomer can also have one kind or two or more following material, i.e.,：Tetrafluoroethene, CTFE, trichloro ethylene, hexafluoro Propylene, ethlyene dichloride maleic anhydride, maleic acid, maleate, monomethyl maleate etc..It can enumerate and be carried out to polymer (B) Above-mentioned monomer is added during polymerization, by being copolymerized the method for importing main chain, and the method for side chain importing is turned to by grafting.This Outside, can also be by controlling Head-to-Head the keys (- CH of vinylidene fluoride units2-CF2-CF2-CH2-) ratio adjust Fusing point.
The lower limit of the weight average molecular weight of polymer (B) containing vinylidene fluoride units is preferably more than 100,000, more preferably For more than 150,000, higher limit is preferably less than 750,000, and more preferably less than 700,000.
By the way that the fusing point of the polymer (B) containing vinylidene fluoride units and weight average molecular weight are located at into above-mentioned preferred scope It is interior, heating with pressurized conditions, polymer (B) is readily flowed, is peeled off when can obtain sufficient dry when bending strength, drying Power.If the fusing point of polymer (B) has exceeded the higher limit of above-mentioned preferred scope, bending strength, drying during in order to obtain dry When peeling force, it is necessary to pressed temperature in improving the manufacturing process of coiling body.So, using polyolefin as the micro- of main component Perforated membrane may shrink.In addition, if the weight average molecular weight of polymer (B) has exceeded the higher limit of above-mentioned preferred scope, divide The connection amount increase of subchain, possibly can not fully flow under an increased pressure.If the weight average molecular weight of polymer (B) is less than above-mentioned The lower limit of preferred scope, then because the connection amount of strand is very few, mechanical strength of resin dies down, and the cohesion of porous layer easily occurs Destroy.
[3] acrylic resin
Moreover, porous layer is by containing acrylic resin, bending strength and peeling force when drying when can improve dry.Only contain Vinylidene fluoride-hexafluoropropene (VdF-HFP) copolymer (A) and during polymer (B) containing vinylidene fluoride units, can not be obtained The barrier film of peeling force when meeting bending strength when bending strength during drying, moistening and drying.
Acrylic resin is preferably (methyl) acrylate polymer or its copolymer.In the present invention, (methyl) acrylic acid Ester represents acrylate (acrylic acid) and methacrylate (methacrylic acid).As (methyl) acrylate, third can be enumerated E pioic acid methyl ester, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2- ethylhexyl acrylates, methyl methacrylate Ester, EMA, n-BMA, Tert-butyl Methacrylate, 2- ethylhexy methacrylates etc.. Particularly preferably contain butyl acrylate.Butyl acrylate improves the flexibility of film, can also expect to suppress the effect that particle comes off Fruit.
From the viewpoint of the cohesive with electrode, more preferably acrylic resin is (methyl) acrylate and has cyano group Monomer copolymer.As the monomer with cyano group, the α with cyano group, β-ethylene unsaturated monomer can be enumerated, for example, Preferably acrylonitrile or methacrylonitrile.Moreover, particularly preferably acrylic resin is the copolymer of butyl acrylate and acrylonitrile, It by controlling the adjustable swellbility for electrolyte of mol ratio, and can make resin that there is suitable flexibility, can also carry Bending strength during high-humidity.In acrylic resin the lower limit of the content of butyl acrylate units be preferably 50 molar percentages with On, more preferably more than 55 molar percentages, higher limit is preferably more preferably 70 molar percentages below 75 molar percentages Below.By the way that the lower limit of the content of butyl acrylate units in acrylic resin is located in above-mentioned preferred scope, can make more Hole matter layer has the flexibility of appropriateness, and can suppress coming off for perforated membrane.In addition, by by butyl acrylate in acrylic resin The content of unit is located in above-mentioned preferred scope, when can make to dry bending strength and moistening when bending strength, dry when peeling force Balance it is good.
Can be by the side that is illustrated in well-known polymerization, such as Japanese Patent Laid-Open 2013-206846 publications Method obtains acrylic resin.Following methods etc. can be enumerated, i.e.,：Be put into the autoclave with mixer ion exchange water, N-butyl acrylate, acrylonitrile, the polymer particle obtained by emulsion polymerization is dispersed to the water of the dispersion liquid obtained in water Displacement obtains acrylic resin soln into METHYLPYRROLIDONE.During polymerisation, persulfuric acid can also be suitably used Potassium is used as molecular weight regulator as radical polymerization initiator using tert-dodecylmercaotan etc..
The content of acrylic resin relative to vinylidene difluoride-hexafluoropropylene copolymer (A), containing vinylidene fluoride units The gross weight of polymer (B) and acrylic resin, lower limit are preferably more than 4 percentage by weights more preferably 5 weight percents Than more than, higher limit is preferably below 40 percentage by weights, more preferably below 30 percentage by weights, more preferably 20 weights Measure below percentage.By the way that the content of acrylic resin is located in above-mentioned preferred scope, the content of copolymer (A) can be made and gathered The total amount of the content of compound (B) is more than certain value, and can maintain the oxidative resistance of porous layer.
It is above-mentioned by the way that the content of the content of vinylidene difluoride-hexafluoropropylene copolymer (A) and acrylic resin is located at In preferred scope, bending strength and peeling force when drying when bending strength when porous layer can obtain dry, moistening.
[4] particle
Porous layer in the present invention can also contain particle.By containing particle in porous layer, positive pole and negative pole can be reduced Between occur short circuit probability, and can expect improve security.As particle, inorganic particulate or organic filler can be enumerated.
As inorganic particulate, calcium carbonate, calcium phosphate, amorphous silica, crystalline glass particle, kaolinite can be enumerated Soil, talcum, titanium dioxide, aluminum oxide, silica-alumina composite oxide particle, barium sulfate, calcirm-fluoride, lithium fluoride, boiling Stone, molybdenum sulfide, mica, boehmite and magnesia etc..Especially from the crystalline growth of vinylidene difluoride-hexafluoropropylene copolymer Property, cost, easness of starting with set out, preferably titanium dioxide, aluminum oxide, boehmite, barium sulfate.
As organic filler, crosslinked polystyrene particle, crosslinked acrylic resin particle and cross-linked methyl third can be enumerated E pioic acid methyl ester class particle etc..
For the content of contained particle relative to the gross weight of porous layer, higher limit is preferably 90 weight percents in porous layer Than following, more preferably below 85 percentage by weights, lower limit is preferably more than 50 percentage by weights more preferably 60 weight hundred Divide more than ratio, more preferably more than 65 percentage by weights.By the way that the content of particle is located in above-mentioned preferred scope, easily Realize the good balance of vapour lock degree.
If containing the particle for whetheing there is cohesive in porous layer, bending strength and drying when bending strength, drying when moistening When peeling force exist reduce tendency.But in the porous layer according to the resin component acquisition of the present invention, it is in even if containing Particle in above-mentioned preferred scope, for electrode moistening when bending strength, dry when bending strength and peeling force when drying Balance is also good.
From the viewpoint of particle comes off, the average grain diameter of particle is preferably the average discharge fine pore of micro-porous film More than 1.5 times, less than 50 times, more preferably more than 2.0 times, less than 20 times.Determined according to JIS K3832 and ASTM F316-86 Average discharge fine pore, for example, using aperture tester (PMI companies manufacture, CFP-1500A) according to Dry-up, Wet-up Sequential determination.During Wet-up, using PMI company systems Galwick (trade name) known to surface tension to being sufficiently impregnated Micro-porous film applies pressure, using the aperture of the conversion pressure penetrated by air as maximum diameter of hole.On average discharge Fine pore, pressure, the 1/2 of flow curve inclined curve and the curve intersection of Wet-up measure are represented in being determined according to Dry-up Point pressure, converse aperture.When reduced pressure is with aperture, following formulas are used.
D=C γ/P (in above formula, " d (μm) " be micro-porous film aperture, " γ (mN/m) " be liquid surface tension, " P (Pa) " it is pressure, " C " is constant)
From battery winding when and winding core sliding and particle come off from the viewpoint of, the average grain diameter of particle is preferably 0.3 μm to 1.8 μm, more preferably 0.5 μm to 1.5 μm, more preferably 0.9 μm to 1.3 μm.Laser diffraction side can be used The average grain diameter of the measure device measure particle of formula and dynamic light scattering mode.For example, using ultrasonic probe, pass through granularity point Cloth measure device (Nikkiso Company Limited's manufacture, Microtrac HRA) measure is dispersed in the aqueous solution containing surfactant Particle, during preferably volume is converted since small particles side accumulate 50% when particle diameter (D50) value as average grain diameter.Grain The shape of son can enumerate spherical, substantially spherical, tabular, needle-like, be not particularly limited.
[5] physical characteristic of porous layer
The one side thickness of porous layer is preferably 0.5 μm to 3 μm, more preferably 1 μm to 2.5 μm, more preferably 1 μm to 2 μ m.If one side thickness is more than 0.5 μm, bending strength when being able to ensure that moistening, bending strength and peel off when drying when drying Power.It if one side thickness is less than 3 μm, can suppress to wind volume, be adapted to the high capacity of battery that will develop from now on.
The void content of porous layer is preferably 30% to 90%, and more preferably 40% to 70%.By by porous layer Void content is located in above-mentioned preferred scope, can prevent the resistance of barrier film from increasing, negotiable high current, and can maintain film-strength.
[6] manufacture method of battery separator
The manufacture method of the battery separator of the present invention includes following process (1) to (3) successively.
(1) vinylidene difluoride-hexafluoropropylene copolymer (A) and polymer (B) containing vinylidene fluoride units are dissolved to solvent The process for obtaining fluororesin solution afterwards.
(2) after acrylic resin soln is added in fluorine-type resin solution and is mixed, the process that obtains coating fluid.
(3) by coating solution to micro-porous film, the process for being immersed in solidification liquid and being cleaned, dried.
(1) process for obtaining fluorine-type resin solution
As long as solvent can dissolve vinylidene difluoride-hexafluoropropylene copolymer (A) and the polymer containing vinylidene fluoride units (B) acrylic resin is dissolved or is disperseed, and can be mixed with solidification liquid, is not particularly limited.From dissolubility, low volatilization From the viewpoint of property, solvent is preferably METHYLPYRROLIDONE.
When setting the porous layer containing particle, the fluororesin solution (being also dispersion liquid) that preparation in advance is dispersed with particle is very heavy Will.Vinylidene difluoride-hexafluoropropylene copolymer (A) and the polymer (B) containing vinylidene fluoride units are dissolved in solvent, Particle is added while stirring, it is pre-dispersed by the stirring such as disperser (DISPER) regular hour (e.g., from about 1 hour) progress, Then by making the scattered process (dispersion step) of particle using sand mill and paint shaker, the fluorine for reducing particle coacervation is obtained Resin solution.
(2) process for obtaining coating fluid
It is molten in the fluororesin of the polymer (B) containing vinylidene difluoride-hexafluoropropylene copolymer (A) and containing vinylidene fluoride units Acrylic resin soln is added in liquid, such as by preparing coating fluid after the Three-One Motor mixing with paddle.
Acrylic resin soln is to dissolve acrylic resin or be dispersed to the solution obtained in solvent, used herein molten Agent be preferably and process (1) identical solvent.Especially from the viewpoint of dissolubility, low volatility, preferably N- methyl -2- Pyrrolidones.From the viewpoint of operability, preferably after polypropylene acid resin, add METHYLPYRROLIDONE and carry out Distillation etc., acrylic resin soln is obtained after line replacement is entered to solvent.
When setting the porous layer containing particle, the fluororesin solution (dispersion liquid) for being dispersed with particle is added to acrylic acid It is critically important in resin solution.That is, it is critically important to be added without acrylic resin in dispersion step.If by vinylidene fluoride- Hexafluoropropylene copolymer (A), polymer (B), acrylic resin and particle containing vinylidene fluoride units are simultaneously added to molten Coating fluid is prepared in agent, then is speculated because the hydrophilic group and acrylic resin that contain in copolymer (A) (especially contain acrylic acid During butyl ester) heat when scattered and cut-out, coating fluid gradually start gelation, it is not suitable for industrial use.Moreover, thickened Influence, when the one side thickness of porous layer is less than 3 μm, it is difficult to carry out film coated.In manufacturing method according to the invention Process (1), (2), the gelation of coating fluid can be suppressed and carry out film coated, the preservation that can also improve coating fluid is stable Property.
(3) by coating solution to micro-porous film, the process for being immersed in solidification liquid and being cleaned, dried
By coating solution to micro-porous film, the micro-porous film after coating is immersed in solidification liquid, makes vinylidene fluoride-hexafluoro Propylene copolymer (A), the polymer (B) containing vinylidene fluoride units and acrylic resin are separated, with three-dimensional Make its solidification in the state of mesh configuration, and cleaned, dried.Thus, the table in micro-porous film and micro-porous film can be obtained Face has the battery separator of porous layer.
As by the method for coating solution to micro-porous film, using well-known method, for example, can enumerate Dip coating, reverse roll rubbing method, gravure coating process, kiss-coating method, roller brush rubbing method, spraying process, air knife coating method, Meyer rod Formula rubbing method, tubulose scraper for coating method (pipe doctor method), scraper for coating method and die coating method (diecoating) Can individually or combination is implemented Deng, these methods.
Solidification liquid is preferably water, preferably containing vinylidene difluoride-hexafluoropropylene copolymer (A), list containing vinylidene fluoride The aqueous solution of the polymer (B) of member and the percentage by weight of good solvent 1 to 20 of acrylic resin, more preferably containing 5 to 15 weights Measure the aqueous solution of percentage.As good solvent, METHYLPYRROLIDONE, DMF, N, N- diformazans can be enumerated Yl acetamide.Dip time in solidification liquid is preferably more than 3 seconds.The upper limit is simultaneously unrestricted, but 10 seconds just enough.
Usable water is cleaned.When drying, such as less than 100 DEG C of hot blast can be used to be dried.
The battery separator of the present invention can be used in Ni-MH battery, nickel-cadmium cell, nickel-zinc cell, smee cell, lithium ion The battery separator of the secondary cells such as secondary cell, lighium polymer secondary battery, lithium-sulfur cell etc..Particularly preferably it is used as lithium ion The barrier film of secondary cell.
[7] physical characteristic of battery separator
Bending strength is preferably more than 4N during the moistening of battery separator.The higher limit of bending strength does not limit especially during moistening It is fixed, but it is just enough to reach 15N.By being located in above-mentioned preferred scope, the part that can suppress barrier film and electrode interface face is dissociated, And the increase of battery internal resistance and the reduction of battery behavior can be suppressed.
Bending strength is preferably more than 5N during the drying of battery separator.The higher limit of bending strength is not special when drying Limit, but it is just enough to reach 25N.By being located in above-mentioned preferred scope, can expect to suppress bending, being askew for rolled electrode bodies Tiltedly.
Peeling force is preferably more than 8N/m during the drying of battery separator.The higher limit of peeling force does not limit especially when drying It is fixed, but it is just enough to reach 40N/m.By being located in above-mentioned preferred scope, rolled electrode bodies or laminate electrode physical efficiency can be expected It is enough to be carried in the state of electrode body is not scattered.
Peeling force battery separator meets bending strength when bending strength and drying during moistening and dried simultaneously when, specifically For, during the moistening for meeting to determine by assay method as shown below bending strength be more than 4N, drying when bending strength be More than 5N and peeling force is more than 8N/m condition when drying.
Hereinafter, embodiment is enumerated, the present invention is specifically described, but the present invention is not exposed to any of these embodiments Limitation.In addition, the measured value in embodiment is the value determined by the following method.
1. bending strength during moistening
In general, positive pole uses the adhesive of fluororesin, when having the porous layer of fluorine resin on barrier film, pass through fluorine tree Phase counterdiffusion between fat, is easy to ensure cohesive.On the other hand, negative pole uses the adhesive beyond fluororesin, fluorine-type resin It is difficult to spread, therefore, compared with positive pole, negative pole is difficult to obtain the cohesive with barrier film.Therefore, in this measurement, by under Bending strength is stated as index, evaluates the cohesive between barrier film and negative pole.
(1) making of negative pole
The aqueous solution containing the mass parts of carboxy methyl cellulose 1.5 is added into the mass parts of Delanium 96.5 and mixed, It is re-used as the solid constituent addition mass parts of styrene-butadiene latex 2 to be mixed, forms the slurry containing composite additives to negative electrodes.By this containing negative The slurry of pole compound additive is uniformly applied to the two sides for the negative electrode collector being made up of the copper foil that thickness is 8 μm, shape after drying Into negative electrode layer, then, with roll squeezer compression forming, the density for making the negative electrode layer outside removing collector is 1.5g/cm3, thus make Make negative pole.
(2) making of experiment coiling body
The barrier film that will be made in the negative pole (operating direction 161mm × width 30mm) of above-mentioned making and embodiment and comparative example (operating direction 160mm × width 34mm) is overlapping, using metallic plate (length 300mm, width 25mm, thickness 1mm) as volume Around core, barrier film and negative pole are wound in a manner of barrier film is in inner side, experiment coiling body is obtained after extracting metallic plate.Experiment is wound Body length about 34mm × width about 28mm.
(3) assay method of bending strength when moistening
Overlapping 2 laminated films (length 70mm, width 65mm, thickness 0.07mm) being made up of polypropylene, by experiment coiling body It is put into the 4 bag-shaped laminated films in during welding 3.Make LiPF6It is dissolved in 1mol/L ratio with 3:7 volume ratio is mixed Conjunction has in the solvent of ethylene carbonate and methyl ethyl carbonate, obtains the μ L of electrolyte 500, is laminated the electrolyte certainly in glove box The opening portion injection of film, makes its leaching be contained in experiment coiling body, and seal one side of opening portion by vacuum sealer.
Then, the experiment coiling body for enclosing laminated film is clamped with 2 pads (thickness 1mm, 5cm × 5cm), is heated by precision Pressue device (Xindong Industry Co's manufacture, CYPT-10) is pressurizeed 2 minutes with 98 DEG C, 0.6MPa, is carried out at room temperature cold But.Keep enclosing the state of laminated film, (Shimano Inc makes using universal testing machine with coiling body to the experiment after pressurization Manufactured, AGS-J) determine bending strength when moistening.Recorded in detail below.
By 2 aluminum L-shaped angle bar (length 1mm, 10mm × 10mm, length 5cm) by 90 ° of parts upward, in a manner of end part aligning Configured in parallel is carried out, is fixed using 90 ° of parts as fulcrum, it is 15mm to make distance between the fulcrum.Configuration examination in the following manner Test and use coiling body, i.e.,：Make the centre of the distance between the fulcrum of 2 aluminum L-shaped angle bar i.e. at 7.5mm, the width with experiment coiling body Spend the midpoint alignment on the side (about 28mm) in direction, and the side of the length direction without departing from L-shaped angle bar.
Then, as pressure head, the side (about 34mm) of the length direction of experiment coiling body is made without departing from aluminum L-shaped angle bar (thickness 1mm, 10mm × 10mm, length 4cm) length direction side, and both are parallel, make the width of experiment coiling body The midpoint on side and 90 ° of section aligneds of aluminum L-shaped angle bar, aluminum L-shaped angle bar is fixed in a manner of 90 ° are partially toward omnipotent On the load cell (load cell capacity 50N) of testing machine.By 3 experiment coiling bodies with loading speed 0.5mm/min The bending strength when average value of the maximum test force obtained after being measured is as moistening.
2. bending strength when drying
(1) making of negative pole
Use bending strength identical negative pole when being moistened with above-mentioned 1..
(2) making of experiment coiling body
Use bending strength identical experiment coiling body when being moistened with above-mentioned 1..
(3) assay method of bending strength when drying
The experiment coiling body got ready with 2 pads (thickness 1mm, 5cm × 5cm) clamping is (new by precision heating pressue device Eastern Industrial Co., Ltd's manufacture, CYPT-10) pressurizeed 2 minutes with 70 DEG C, 0.6MPa, cooled down at room temperature.Used on experiment Coiling body, it is same with the assay method of bending strength during above-mentioned 1. moistening to configure, use universal testing machine (Shimano Inc's system Make manufactured, AGS-J), average value of 3 experiments with the maximum test force obtained after coiling body will be determined under the following conditions As bending strength when drying.
Distance between the fulcrum：15mm.
Load cell capacity：50N.
Loading speed：0.5mm/min.
3. peeling force when drying
(1) making of negative pole
Use bending strength identical negative pole when being moistened with above-mentioned 1..
(2) making of disbonded test piece
By the negative pole (70mm × 15mm) of above-mentioned making and barrier film (the operating direction 90mm × wide that is made in embodiment and comparative example Spend direction 20mm) it is overlapping, then it is clamped with 2 pads (thickness 0.5mm, 95mm × 27mm), pressurizeed by precision heating Device (Xindong Industry Co's manufacture, CYPT-10) is pressurizeed 2 minutes with 90 DEG C, 8MPa, is cooled down at room temperature.At this The negative side of the laminated body of negative pole and barrier film pastes width 1cm two-sided tape, and the another side of two-sided tape is pasted onto into SUS plates On (thickness 3mm, length 150mm × width 50mm), make the operating direction of barrier film parallel with SUS plate length directions.As Disbonded test piece.
(3) assay method of peeling force when drying
Using universal testing machine (Shimadzu Scisakusho Ltd manufacture, AGS-J) by diaphragm clip in the chuck of load cell side, 180 degree disbonded test is implemented for 300mm/ points with test speed.Measured value in disbonded test from stroke 20mm to 70mm is carried out It is average, the peeling force using the value after equalization as disbonded test piece.3 disbonded test pieces are determined altogether, by peeling force The value that average value enters after line width conversion is as peeling force (N/m) when drying.
4. fusing point test
Using differential scanning heat analytical equipment (Co., Ltd. PerkinElmer manufacture DSC), it is put into 7mg's in crucible is determined Resin determines as measurement sample according to following condition.After initial heating, cooling, by the endothermic peak during heating of the 2nd time Peak value as fusing point.
Heating, cooling velocity：±10℃/min.
Measurement temperature scope：30 DEG C to 230 DEG C.
5. thickness
Using contact film thickness gauge (M Co., Ltd. itutoyo systems " Lightomatic " (registration mark) series318), pass through Superhard sphere gauge headDetermined under conditions of 0.01N is aggravated at 20, using the average value of the measured value of acquisition as film It is thick.
[embodiment]
Embodiment 1
[copolymer (a)]
As copolymer (A), synthetic copolymer (A) in the following manner.By vinylidene fluoride, hexafluoropropene and maleic acid list first Ester synthesizes vinylidene difluoride-hexafluoropropylene copolymer (a) as initiation material by suspension polymerization.Determined and confirmed by NMR The weight average molecular weight of the copolymer (a) of acquisition is 1,500,000, and the mol ratio of vinylidene fluoride/hexafluoropropene/monomethyl maleate is 98.0/1.5/0.5。
[copolymer (b1)]
As copolymer (B), synthetic copolymer (b1) in the following manner.Vinylidene fluoride and hexafluoropropene is former as starting Material, vinylidene difluoride-hexafluoropropylene copolymer (b1) is synthesized by suspension polymerization.The copolymerization for confirming to obtain is determined by NMR The weight average molecular weight of thing (b1) is 300,000, and the mol ratio of vinylidene fluoride/hexafluoropropene is 93/7.
[acrylic resin]
Using acrylonitrile, n-butyl acrylate as initiation material, by emulsion polymerization method acrylic acid synthesizing resin, then, by water Displacement obtains the acrylic resin soln that solid component concentration is 5 mass percents into METHYLPYRROLIDONE.Pass through NMR measure confirms that the Tg of the acrylic resin obtained is -5 DEG C, and the mol ratio of acrylonitrile unit/acrylic ester unit is 38/62.
[making of battery separator]
The mass parts of copolymer (a) 7.1, the mass parts of copolymer (b1) 21.4 and the mass parts of NMP 359.3 are mixed, then, Disperser (DISPER) is used to stir while adding aluminium oxide particles (1.1 μm of average grain diameter) 70 mass parts, then use disperser (DISPER) stirred in advance with 2000rpm 1 hour.Next, using DYNO-MILL, (SHINMARU ENTERPRISES are manufactured DYNO-MILL Multi Lab (1.46L containers, filling rate 80%,Alumina bead)), flow be 11kg/hr, Circular velocity is handled 3 times under conditions of being 10m/s, obtains dispersion liquid.Acrylic resin soln is mixed in dispersion liquid, is stirred with band The Three-One Motor of leaf with 500rpm stir 30 minutes, obtained after filtering solid component concentration for 20.5 mass percents, Aluminium oxide particles：Copolymer (a)：Copolymer (b1)：The weight ratio of acrylic resin is 70:7.1:21.4:1.5 coating fluid. On the two sides for the microporous polyethylene film that thickness is 7 μm by dip coating applied coating solution, make its dipping in aqueous, use is pure After water purification cleaning, with 50 DEG C of dryings, the battery separator that thickness is 11 μm is obtained.
Embodiment 2
Except the use of solid component concentration being 18.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:14.3:14.2:Beyond 1.5 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 3
Except the use of solid component concentration being 15.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:21.4:7.1:Beyond 1.5 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 4
Except the use of solid component concentration being 20.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:6.8:20.2:Beyond 3.0 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 5
Except the use of solid component concentration being 18.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:13.5:13.5:Beyond 3.0 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 6
Except the use of solid component concentration being 15.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:20.2:6.8:Beyond 3.0 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 7
Except the use of solid component concentration being 20.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:6.4:19.1:Beyond 4.5 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 8
Except the use of solid component concentration being 18.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:12.8:12.7:Beyond 4.5 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 9
Except the use of solid component concentration being 19.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:19.1:6.4:Beyond 4.5 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 10
Except the use of solid component concentration being 20.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:6.0:18.0:Beyond 6.0 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 11
Except the use of solid component concentration being 18.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:12.0:12.0:Beyond 6.0 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 12
Except the use of solid component concentration being 15.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 70:18.0:6.0:Beyond 6.0 coating fluid, in the same manner as example 1 obtain battery with every Film.
Embodiment 13
Except the use of solid component concentration being 21.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 78.8:9.0:9.0:Beyond 3.2 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 14
Except the use of solid component concentration being 25.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1)：Propylene The weight ratio of acid resin is 85.2:6.3:6.3:Beyond 2.2 coating fluid, battery is obtained in the same manner as example 1 and is used Barrier film.
Embodiment 15
[copolymer (b2)]
As copolymer (B), synthetic copolymer (b2) in the following manner.Using vinylidene fluoride, tetrafluoroethene as initiation material, Vinylidene fluoride-TFE copolymer (b2) is synthesized by suspension polymerization.The inclined difluoro second for confirming to obtain is determined by NMR The weight average molecular weight of alkene-TFE copolymer (b2) is 280,000, and the mol ratio of vinylidene fluoride/tetrafluoroethene is 90/10.
[making of battery separator]
Except replacing copolymer (b1) using copolymer (b2), use using solid component concentration as 18.0 mass percents, oxidation Aluminum particulate：Copolymer (a)：Copolymer (b2)：The weight ratio of acrylic resin is 70:13.5:13.5:Prepared by 3.0 condition Beyond coating fluid, battery separator is obtained in the same manner as example 1.
Embodiment 16
The mass parts of copolymer (a) 45, the mass parts of copolymer (b1) 45 and the mass parts of NMP 1329 are made to mix and dissolve.In the liquid Middle mixing acrylic resin soln, stirred 30 minutes with 500rpm with the Three-One Motor with paddle, obtained after filtering Solid component concentration is 6.6 mass percents, copolymer (a)：Copolymer (b1)：The weight ratio of acrylic resin is 45.0: 45.0:10.0 coating fluid.On the two sides for the microporous polyethylene film that thickness is 7 μm by dip coating applied coating solution, make it Dipping in aqueous, after being cleaned with pure water, with 50 DEG C of dryings, obtains the battery separator that thickness is 11 μm.
Comparative example 1
The mass parts of copolymer (b1) 30.0, the mass parts of NMP 334.8 are mixed, then, while with disperser (DISPER) Stirring is while add aluminium oxide particles (1.1 μm of average grain diameter) 70 mass parts, then stirred in advance with 2000rpm with disperser (DISPER) Mix 1 hour.Next, using DYNO-MILL, (SHINMARU ENTERPRISES manufacture DYNO-MILL Multi Lab (1.46L containers, filling rate 80%,Alumina bead)), in the condition that flow is 11kg/hr, circular velocity is 10m/s It is lower to handle 3 times, obtain dispersion liquid.Solid component concentration is obtained after being filtered as 23.0 mass percents, aluminium oxide particles：Altogether The weight ratio of polymers (b1) is 70:30.0 coating fluid.Pass through dip coating on the two sides for the microporous polyethylene film that thickness is 7 μm Applied coating solution, make its dipping in aqueous, after being cleaned with pure water, with 50 DEG C of dryings, obtain the battery that thickness is 11 μm Use barrier film.
Comparative example 2
In addition to the mass parts of mixed copolymer (a) 7.5, the mass parts of copolymer (b1) 22.5 and the mass parts of NMP 387.8, with than After being prepared, filtered compared with the identical mode of example 1, obtain using solid component concentration as 20.5 mass percents, aluminium oxide particles： Copolymer (a)：The weight ratio of copolymer (b1) is 70:7.5:Coating fluid prepared by 22.5 condition.By the coating fluid with than After being coated compared with the identical mode of example 1, battery separator is obtained.
Comparative example 3
Except using using solid component concentration as 18.0 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1) Weight ratio is 70:15.0:Beyond coating fluid prepared by 15.0 condition, obtained in a manner of with the identical of comparative example 2 battery with every Film.
Comparative example 4
Except using using solid component concentration as 15.5 mass percents, aluminium oxide particles：Copolymer (a)：Copolymer (b1) Weight ratio is 70:22.5:Beyond coating fluid prepared by 7.5 condition, obtained in a manner of with the identical of comparative example 2 battery with every Film.
Comparative example 5
In addition to the mass parts of mixed copolymer (a) 30, the mass parts of NMP 669.2, made in a manner of with the identical of comparative example 1 After standby, filtering, obtain using solid component concentration as 13.0 mass percents, aluminium oxide particles：The weight ratio of copolymer (a) is 70:Coating fluid prepared by 30.0 condition.After the coating fluid is coated in a manner of with the identical of comparative example 1, battery is obtained Use barrier film.
Comparative example 6
Except using using solid component concentration as 23.0 mass percents, aluminium oxide particles：Copolymer (b1)：Acrylic resin Weight ratio is 70:28.5:Beyond coating fluid prepared by 1.5 condition, obtain in the same manner as example 1 battery with every Film.
Comparative example 7
Except using using solid component concentration as 13.0 mass percents, aluminium oxide particles：Copolymer (a)：Acrylic resin Weight ratio is 70:28.5:Beyond coating fluid prepared by 1.5 condition, obtain in the same manner as example 1 battery with every Film.
Comparative example 8
Except using using solid component concentration as 23.0 mass percents, aluminium oxide particles：Copolymer (b1)：Acrylic resin Weight ratio is 70:27.0:Beyond coating fluid prepared by 3.0 condition, obtain in the same manner as example 1 battery with every Film.
Comparative example 9
Except using using solid component concentration as 13.0 mass percents, aluminium oxide particles：Copolymer (a)：Acrylic resin Weight ratio is 70:27.0:Beyond coating fluid prepared by 3.0 condition, obtain in the same manner as example 1 battery with every Film.
Comparative example 10
Except using using solid component concentration as 23.0 mass percents, aluminium oxide particles：Copolymer (b1)：Acrylic resin Weight ratio is 70:25.5:Beyond coating fluid prepared by 4.5 condition, obtain in the same manner as example 1 battery with every Film.
Comparative example 11
Except using using solid component concentration as 23.0 mass percents, aluminium oxide particles：Copolymer (b1)：Acrylic resin Weight ratio is 70:24.0:Beyond coating fluid prepared by 6.0 mode, in the same manner as example 1 obtain battery with every Film.
Comparative example 12
[copolymer (b3)]
Using vinylidene fluoride and tetrafluoroethene as initiation material, vinylidene fluoride-tetrafluoroethene is synthesized by suspension polymerization Copolymer.The weight average molecular weight that the vinylidene fluoride-TFE copolymer for confirming to obtain is determined by NMR is 950,000, inclined two The mol ratio of PVF/tetrafluoroethene is 95/5.
[making of battery separator]
Except replacing copolymer (b1) using copolymer (b3), use using solid component concentration as 18.0 mass percents, oxidation Aluminum particulate：Copolymer (a)：Copolymer (b3)：The weight ratio of acrylic resin is 70:13.5:13.5:Prepared by 3.0 condition Beyond coating fluid, battery separator is obtained in the same manner as example 1.
The characteristic of the battery separator obtained in embodiment 1 to 16, comparative example 1 to 12 is as shown in table 1.
[table 1]
The content (%) of copolymer (A)*：Represent copolymer (A) relative to copolymer (A) and the weight of the gross weight of polymer (B) Measure percentage.
The content (%) of acrylic resin**：Represent acrylic resin relative to copolymer (A), polymer (B) and acrylic acid The percentage by weight of the gross weight of resin.
In figure：
1 negative pole
2 battery separators
3 laminated films
4 aluminum L-shaped angle bar
5 pressure heads aluminum L-shaped angle bar

Claims (15)

1. a kind of battery separator, it is characterised in that there is micro-porous film and be at least located at the Porous of micro-porous film one side Layer, the porous layer contain vinylidene difluoride-hexafluoropropylene copolymer (A), the polymer (B) containing vinylidene fluoride units with And acrylic resin, the vinylidene difluoride-hexafluoropropylene copolymer (A) is containing hydrophilic group and 0.3 molar percentage to 3 moles The hexafluoropropene unit of percentage, the fusing point of the polymer (B) containing vinylidene fluoride units for more than 60 DEG C 145 DEG C with Under, weight average molecular weight is less than more than 100,000 75 ten thousand.
2. battery separator according to claim 1, it is characterised in that vinylidene difluoride-hexafluoropropylene copolymer (A) Weight average molecular weight is more than 750,000 and is less than 2,000,000.
3. battery separator according to claim 1 or 2, it is characterised in that porous layer contains particle.
4. the battery separator according to any claim in claims 1 to 3, it is characterised in that vinylidene fluoride-six The content of fluoropropene copolymer (A) accounts for vinylidene difluoride-hexafluoropropylene copolymer (A) and the polymer containing vinylidene fluoride units (B) more than 15 percentage by weights of gross weight below 85 percentage by weights, the content of acrylic resin accounts for vinylidene fluoride-six 4 weight percents of the gross weight of fluoropropene copolymer (A), the polymer (B) containing vinylidene fluoride units and acrylic resin Than more than below 40 percentage by weights.
5. the battery separator according to any claim in Claims 1-4, it is characterised in that acrylic resin is (methyl) acrylate and with cyano group monomer copolymer.
6. the battery separator according to any claim in Claims 1-4, it is characterised in that acrylic resin is Copolymer containing butyl acrylate.
7. the battery separator according to any claim in Claims 1-4, it is characterised in that acrylic resin is The copolymer of butyl acrylate and acrylonitrile.
8. the battery separator according to claim 6 or 7, it is characterised in that butyl acrylate in acrylic resin Content is 50 molar percentages to 75 molar percentages.
9. the battery separator according to any claim in claim 1 to 8, it is characterised in that vinylidene fluoride-six The content of the hydrophilic group of fluoropropene copolymer (A) is 0.1 molar percentage to 5 molar percentages.
10. the battery separator according to any claim in claim 1 to 9, it is characterised in that bent during moistening strong Spend for more than 4N, bending strength is more than 5N when drying, and peeling force is 8N/m when drying.
11. the battery separator according to any claim in claim 3 to 10, it is characterised in that the content of particle Account for more than 50 percentage by weights of porous layer gross weight below 90 percentage by weights.
12. the battery separator according to any claim in claim 3 to 11, it is characterised in that particle includes choosing It is at least one kind of in the group that free oxidation aluminium, titanium oxide, boehmite, barium sulfate form.
13. the battery separator according to any claim in claim 1 to 12, it is characterised in that porous layer One side thickness is 0.5 μm to 3 μm.
14. the battery separator according to any claim in claim 1 to 13, it is characterised in that micro-porous film is Polyolefin micro porous polyolefin membrane.
15. a kind of manufacture method of battery separator, it is characterised in that for described in any claim in claim 1 to 14 Battery separator manufacture method, successively including following process：
(1) vinylidene difluoride-hexafluoropropylene copolymer (A) and polymer (B) containing vinylidene fluoride units are dissolved to solvent The process for obtaining fluorine-type resin solution afterwards；
(2) acrylic resin is dissolved to the acrylic resin soln obtained after solvent to be added in fluorine-type resin solution, mixing The process for obtaining coating fluid afterwards；
(3) will be immersed in after coating solution to micro-porous film in solidification liquid, and the process cleaned, dried, described inclined two Hexafluoropropene unit of the viton copolymers (A) containing hydrophilic group and 0.3 molar percentage to 3 molar percentages, The fusing point of the polymer (B) containing vinylidene fluoride units is less than more than 60 DEG C 145 DEG C, and weight average molecular weight is more than 100,000 Less than 750000, the acrylic resin contains butyl acrylate units.
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KR20150106810A (en) * 2013-11-21 2015-09-22 삼성에스디아이 주식회사 Separators and secondary battery using the separator
WO2015170594A1 (en) * 2014-05-08 2015-11-12 帝人株式会社 Separator for non-aqueous secondary batteries and method for producing same, and non-aqueous secondary battery

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CN108630866A (en) * 2018-04-25 2018-10-09 苏州名列膜材料有限公司 A kind of hydrophilic perfluor battery diaphragm and preparation method thereof
CN108630866B (en) * 2018-04-25 2021-03-19 苏州名列膜材料有限公司 Hydrophilic perfluoro battery diaphragm and preparation method thereof
CN111435761A (en) * 2019-01-11 2020-07-21 中信国安盟固利动力科技有限公司 All-solid-state lithium ion battery and hot-pressing preparation method of multilayer electrolyte membrane thereof
CN111435761B (en) * 2019-01-11 2021-08-10 荣盛盟固利新能源科技有限公司 All-solid-state lithium ion battery and hot-pressing preparation method of multilayer electrolyte membrane thereof
CN113574732A (en) * 2019-03-18 2021-10-29 帝人株式会社 Separator for nonaqueous secondary battery and nonaqueous secondary battery
CN113574732B (en) * 2019-03-18 2024-03-22 帝人株式会社 Separator for nonaqueous secondary battery and nonaqueous secondary battery
CN113140864A (en) * 2021-03-04 2021-07-20 乐凯胶片股份有限公司 Diaphragm and preparation method and application thereof

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CN107492625B (en) 2021-02-26
KR102209887B1 (en) 2021-02-01

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