WO2007116672A1 - Film microporeux polyolefinique - Google Patents

Film microporeux polyolefinique Download PDF

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Publication number
WO2007116672A1
WO2007116672A1 PCT/JP2007/056170 JP2007056170W WO2007116672A1 WO 2007116672 A1 WO2007116672 A1 WO 2007116672A1 JP 2007056170 W JP2007056170 W JP 2007056170W WO 2007116672 A1 WO2007116672 A1 WO 2007116672A1
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WO
WIPO (PCT)
Prior art keywords
microporous membrane
polyolefin microporous
intermediate layer
polyolefin
melting point
Prior art date
Application number
PCT/JP2007/056170
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English (en)
Japanese (ja)
Inventor
Daisuke Inagaki
Yosuke Inoue
Original Assignee
Asahi Kasei Chemicals Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asahi Kasei Chemicals Corporation filed Critical Asahi Kasei Chemicals Corporation
Priority to KR1020087023731A priority Critical patent/KR101060380B1/ko
Priority to CN2007800057953A priority patent/CN101384429B/zh
Priority to JP2008509737A priority patent/JP4931911B2/ja
Publication of WO2007116672A1 publication Critical patent/WO2007116672A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1216—Three or more layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/002—Organic membrane manufacture from melts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/0025—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching
    • B01D67/0027—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching by stretching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/003—Organic membrane manufacture by inducing porosity into non porous precursor membranes by selective elimination of components, e.g. by leaching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1212—Coextruded layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B01D71/261—Polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/027—Thermal properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/52—Separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/02—Diaphragms; Separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/494—Tensile strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/06—Specific viscosities of materials involved
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/24—Mechanical properties, e.g. strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/518—Oriented bi-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention is widely used as a separation membrane used for separation of substances, selective permeation, and the like, and as a separator for electrochemical reaction devices such as alkali, lithium secondary batteries, fuel cells, capacitors, etc.
  • the present invention relates to a microporous membrane.
  • the present invention relates to a polyolefin microporous membrane suitably used as a separator for non-aqueous electrolyte batteries such as lithium ion batteries.
  • Polyolefin microporous membranes are widely used as separation of various substances, selective permeation separation membranes, separators and the like. Specific examples of applications include microfiltration membranes, separators for lithium secondary batteries and fuel cells, separators for capacitors, and various functional materials filled in the holes to create new functions. Examples include base materials for functional membranes. Among these uses, it is particularly suitably used as a separator for lithium ion batteries widely used in notebook personal computers, mobile phones, digital cameras and the like. The reason for this is that the polyolefin microporous membrane is excellent in mechanical strength of the membrane and has good pore blocking properties.
  • Pore occluding property means that when the battery is overheated in an overcharged state, the polymer constituting the membrane melts and closes the pores, blocking the reaction inside the cell and blocking the electric resistance of the membrane. This is a performance that enhances battery safety and ensures battery safety. The lower the temperature at which pore clogging occurs, the higher the safety effect.
  • a separator has a low heat shrinkage rate. This is because when the battery is at a high temperature, the separator shrinks and the isolation function between the electrodes is lost. However, there is generally a contradictory relationship between increasing the strength and the heat shrinkage rate.
  • Patent Document 1 proposes a film in which a microporous film obtained by blending ultrahigh molecular weight polyethylene and polypropylene and a polyethylene microporous film are laminated.
  • this method limits the amount of heat that can be imparted to the membrane in the heat setting step where the difference in pore clogging temperature between the layer of blended ultra-high molecular weight polyethylene and polypropylene and the layer of polyethylene alone is large.
  • it is difficult to achieve both high tensile strength and low thermal shrinkage sufficiently, and the physical properties that can be imparted are limited.
  • the difference in the hole closing temperature between the layers is large, there remains a problem in safety.
  • heat fixation is performed according to the melting point of the low melting point component, low heat shrinkability is also insufficient.
  • Patent Document 2 proposes a film having a high tensile strength by bonding a surface layer made of a high molecular weight polyolefin having a tensile strength of lOOOKgZcm 2 or more and an intermediate layer made of an ethylene-based copolymer.
  • these methods increase the heat shrinkage rate.
  • the hole closing temperature in the entire membrane with a large difference in the hole closing temperature between layers increases.
  • Patent Document 3 proposes a laminated film containing a low melting point component on the positive electrode side.
  • the hole closing property is improved, but the low melting point component is contained only on the positive electrode side, so that the electrode sticking effect is insufficient.
  • the melting point difference between the surface layer and the intermediate layer is large, the heat setting temperature has to be lowered, and the low heat shrinkability is insufficient.
  • Patent Document 4 proposes improvement of hole closing properties by laminating films having different porosity. However, there is no description regarding strength and heat shrinkability. Therefore, heat shrinkage is expected to be high.
  • Patent Document 1 Japanese Patent Laid-Open No. 2002-321323
  • Patent Document 2 JP-A-8-99382
  • Patent Document 3 Japanese Patent Laid-Open No. 2002-367587
  • Patent Document 4 Japanese Patent Application Laid-Open No. 2002-319386
  • An object of the present invention is to provide a polyolefin microporous membrane that maintains safety even when overheated and satisfies mechanical strength.
  • the inventors of the present invention have obtained the intrinsic viscosity of both the surface layer and the intermediate layer in order to obtain a polyolefin microporous membrane having a layered body strength of three or more layers, and By paying attention to the relationship between both surface layers and the intermediate layer, it has been found that the above problems can be solved even with a porous microporous membrane that maintains its porosity and strength. That is, the present invention is as follows.
  • a polyolefin microporous membrane that is a laminate of three or more layers including two surface layers and at least one intermediate layer, wherein the intrinsic viscosity [r?] Of the intermediate layer is 3. OdlZg In addition, the intrinsic viscosity [r?] Of the surface layer is smaller than the intrinsic viscosity [r?] Of the intermediate layer, and the absolute value of the difference between the pore closing temperature of the surface layer and the pore closing temperature of the intermediate layer Polyolefin microporous membrane characterized by a temperature of less than 10 ° C.
  • the absolute value of the difference between the pore closing temperature of the surface layer and the pore closing temperature of the intermediate layer is 5 ° C. or less, wherein the polyolefin fine particles according to any one of (1) to (4) above are characterized. Porous membrane.
  • a polymer material and a plasticizer are melted and kneaded to form a laminated sheet by coextrusion,
  • Polyolefin microporous material obtained by melting and kneading polymer material and plasticizer to form a laminated sheet by coextrusion, biaxial stretching and extracting the plasticizer, followed by heat setting film.
  • the polyolefin microporous membrane of the present invention is high in strength, but has a smaller heat shrinkage ratio when heated than a conventional polyolefin microporous membrane.
  • a sticking effect when the membrane is stuck to an electrode or the like during overheating (hereinafter referred to as a sticking effect), the membrane separation effect can be reliably maintained. Therefore, when the microporous membrane of the present invention is used particularly for a battery separator, it is possible to ensure the safety of the battery.
  • the polyolefin microporous membrane of the present invention needs to have a force of three or more layers including two surface layers and at least one intermediate layer in order to maintain different kinds of physical properties.
  • the surface layer refers to the two outermost layers of the film laminated in three or more layers
  • the intermediate layer refers to the other layers.
  • the intermediate layer may be a single layer or a plurality of layers, but the intermediate layer is preferably a single layer from the viewpoint of productivity.
  • the surface layer is composed of one or more polyolefins.
  • the intermediate layer is also composed of one or more polyolefins.
  • the polyolefin used as the polymer material in the present invention is, for example, polyethylene, a homopolymer of polypropylene, or these homopolymers and ethylene, propylene and 1-butene, 4-methyl-1 pentene, 1 A copolymer of 1-hexene, 1-octene, norbornene and the like, and a mixture of the above-mentioned polymers may be used. From the viewpoint of the performance of the porous membrane, polyethylene and its copolymer are preferred.
  • the polymerization catalysts for these polyolefins include Ziegler Natta catalysts, Phillips catalysts, A catalyst etc. are mentioned. Polyolefin may be obtained by a single-stage polymerization method or may be obtained by a multi-stage polymerization method.
  • polyolefin microporous membrane of the present invention may be added with known additives such as metal stalagmites such as calcium stearate and zinc stearate, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments. Agents can also be mixed and used.
  • the intrinsic viscosity [r?] Of the intermediate layer is 3. OdlZg or more, and the intrinsic viscosity [7?] Of the surface layer is smaller than the intrinsic viscosity [7?] Of the intermediate layer.
  • the intrinsic viscosity of the intermediate layer is preferably 2. OdlZg or more, more preferably 5. OdlZg or less than the intrinsic viscosity of the surface layer.
  • the intrinsic viscosity of the intermediate layer is less than 3. OdlZg, the mechanical strength of the entire film such as piercing strength and tensile strength is lowered. 3. 5dlZg or more is preferred 4. OdlZg or more is more preferred 5. OdlZg or more is more preferred. Further, since the heat shrinkage rate is small, 7. Odl / g or less is preferable.
  • the intrinsic viscosity [ ⁇ ?] Of the surface layer is preferably less than 3. OdlZg, and the point force at which the effect of sticking to the electrode due to stress relaxation at high temperature appears more remarkably is also preferable. Moreover, it is preferable that it is less than 2.5 dlZg in that it has both low fuse characteristics and high short-circuit characteristics. 2. It is more preferable that it is less than OdlZg. Furthermore, from the viewpoint of strength, it is preferably greater than 1. Odl / g.
  • the intrinsic viscosity [r?] Of the layer depends on the intrinsic viscosity [r?] Of the polyolefin component contained in the layer and its ratio.
  • the intrinsic viscosity [7?] Is the intrinsic viscosity [ ⁇ ] at 135 ° C in a decalin solvent based on ASTM-D4020.
  • the difference between the pore closing temperature of the surface layer and the pore closing temperature of the intermediate layer needs to be less than 10 ° C.
  • This temperature difference is preferably 5 ° C or less, more preferably 3 ° C or less.
  • the pore closing temperature depends on the lowest melting point of the polyolefin component contained in the layer. Therefore, the pore closing temperature of the surface layer and the intermediate layer can be set by selecting a polymer yarn having a desired melting point.
  • the hole closing temperature was measured by the following method. That is, a microporous membrane was set in the apparatus shown in FIG. 1 (A), the temperature was raised from 25 ° C to 200 ° C at a rate of 2 ° CZmin, and an alternating current of 1kHz was applied. The temperature and electrical resistance at this time were measured continuously, and the temperature at which the electrical resistance value of the microporous membrane reached 10 3 ⁇ was defined as the pore closing temperature.
  • the surface layer of the polyolefin microporous membrane of the present invention can exhibit the same sticking effect on the positive electrode and the negative electrode in the battery when the membrane is overheated, and can maintain the isolation between the electrodes.
  • the outermost layer is preferably composed of the same component.
  • the pore closing temperature is lowered, it is preferable that it is composed only of polyethylene, and more preferably, both surface layers are composed only of polyethylene!
  • the tensile strength in the MD direction is preferably lOOMPa or more because it is resistant to external impact tests on the battery and is less likely to cause a short circuit due to foreign matter in the battery. More preferably, it is l lOMPa or more.
  • the tensile strength in the TD direction is preferably 30 MPa or more, more preferably 60 MPa or more, because the battery is resistant to external impact tests on the battery and causes a short circuit due to foreign matter in the battery. More preferably 90 MPa or more.
  • the thickness of the entire film is preferably 5 m or more in order to maintain mechanical strength and to completely insulate the electrodes.
  • it is preferably 40 m or less, more preferably 10 to 20 m.
  • the thickness of the surface layer is preferably 0.1 ⁇ m or more in order to easily achieve the sticking effect during overheating, and the strength of the entire film is preferably 10 ⁇ m or less, more preferably 1 to 5 ⁇ m. .
  • the porosity is preferably 20% or more from the viewpoint of preventing an increase in the internal resistance of the battery, and the mechanical strength is preferably 70% or less, and more preferably 30 to 30%. 50%.
  • the air permeability is preferably lOsecZcc or more from the viewpoint of mechanical strength and 1000 sec / cc or less from the viewpoint of permeation performance, more preferably from 30 to 700 secZlOOcc force. I prefer ⁇ 500secZcc! / ⁇ .
  • the puncture strength is 3. ON / 25 ⁇ m or more from the viewpoint of preventing film breakage by the electrode active material. S is preferable, 4. ONZ25 m or more is more preferable 5.5 NZ25 m or more That force S is more preferable.
  • the heat shrinkage rate when measured in a state where the microporous membrane is not restrained at 130 ° C is preferably as low as possible.
  • the thermal shrinkage rate in the MD direction is preferably less than 30%.
  • the thermal shrinkage in the TD direction is preferably 30% or less, more preferably less than 20%, and even more preferably 15%.
  • the above TD tensile strength, overall film thickness, porosity, puncture strength, and crystallinity are determined by the composition ratio of the polyolefin component contained in the layer, extrusion conditions, stretching conditions, plasticizer extraction conditions, and heat setting conditions. Adjustments can be made by appropriate changes.
  • the polyolefin microporous membrane of the present invention is particularly effective when used as a battery separator, the force mainly described for use in this application is the microporous membrane of the present invention. It can also be used as a base material for microfiltration membranes, condenser separators, and functional membranes for filling various functional materials into the holes to bring out new functions. In that case, the membrane has the advantage of being able to increase the stability of the separation membrane and the base material by having the effect that the entire membrane is uniformly clogged in a short time during overheating and the surface of the membrane sticks. .
  • the polymer species and the solvent species are selected.
  • an inorganic substance can also be mixed in a raw material. In this case, the inorganic substance may be extracted during the production process or may be contained as it is.
  • the following composition is preferred.
  • the surface layer and the intermediate layer may be one or more kinds of polyolefin ink.
  • the intrinsic viscosity [r?] Of the surface polymer should be less than 3. OdlZg. More preferably, the polyolefin having an intrinsic viscosity [r?] Of 1.5 dlZg or less is contained in an amount of 50 wt% or more.
  • the polymer of the intermediate layer also has one or more polyolefin forces.
  • the intrinsic viscosity [ ⁇ ?] Of the polymer in the intermediate layer must be 3.
  • OdlZg or more when two or more types of polyolefine are used, the polyolefin having an intrinsic viscosity [r?] Of 4.5 dlZg or more. It is more preferable that it is composed of 30 wt% or more, and it is more preferable that it is composed of 50 wt% or more.
  • the absolute value of the difference between the melting point of the component having the lowest melting point contained in the surface polymer and the melting point of the component having the lowest melting point contained in the intermediate layer polymer is selected to be less than 10 ° C. There is a need to.
  • the absolute value of the difference between the melting points of the components having the lowest melting point contained in the polymer of the surface layer and the intermediate layer is preferably 5 ° C or less, more preferably 3 ° C or less.
  • additives such as metal stones such as calcium stearate and zinc stearate, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments are added to the polymer material. I can do it. These additives are not particularly limited as long as the effect of a force additive that can be added to a raw material, melted and kneaded of a polymer, or after stretching is expressed.
  • the microporous membrane of the present invention can be obtained by melt-kneading a polymer material, extruding it, stretching it, heat setting and heat treatment. More specifically, it can be obtained by a method comprising the following steps (a) to (e).
  • raw materials such as surface layer and intermediate layer polymers are melt-kneaded.
  • the melt-kneading can be performed by a screw extruder such as a single screw extruder or a twin screw extruder, a kneader, a mixer or the like. Some or all of the raw materials may be pre-mixed with a Henschel mixer, a ribbon blender, a tumbler blender, etc. as necessary. If the amount is small, it may be stirred by hand.
  • the temperature at the time of melt kneading is preferably 160 ° C or higher, more preferably 180 ° C or higher. Further, less than 300 ° C is preferable, and less than 240 ° C is more preferable, and less than 230 ° C is more preferable.
  • a plasticizer may be used in order to facilitate the work in the melt-kneading process and the subsequent extrusion process and to facilitate the production of the microporous membrane of the present invention.
  • the plasticizer is added before melting and kneading. As long as it is before the extrusion process, such as during melt kneading.
  • Extrusion molding includes a method of cooling the sheet die force such as a slit die and a T die with an extrusion cast tool, and a method of cooling after an inflation method.
  • the method of co-extrusion with a single die by integrating the gel sheets obtained with the respective extruder force, or the method of extruding each of the gel sheets and superimposing them to heat-seal them Can be made.
  • the coextrusion method is more productive.
  • the obtained film is more preferable because it easily obtains high interlayer adhesion strength and easily forms communication holes between the layers, so that the permeability of the film is easily maintained.
  • the obtained sheet is stretched in a uniaxial or biaxial or more direction. It is preferable to stretch biaxially or more because it is easy to ensure the strength of the resulting film, and it is preferable to stretch in the biaxial direction at the same time because there are fewer stretching steps.
  • stretching method There are no particular restrictions on the stretching method and the number of stretching operations. For example, MD-axial stretching with a roll stretching machine, TD-axial stretching with a tenter, roll stretching machine and tenter, or a combination of tenter and tenter. Examples include secondary biaxial stretching, simultaneous biaxial tenter and simultaneous biaxial stretching by inflation molding.
  • the draw ratio is preferably a total surface magnification of 8 times or more, more preferably 26 times or more, and most preferably a force of 40 times or more.
  • the upper limit of the uniformity of the film is preferably 100 times or less, more preferably 65 times or less.
  • the plasticizer is extracted as necessary.
  • the plasticizer is extracted using an extraction solvent after stretching.
  • the plasticizer is extracted by immersing the stretched sheet in an extraction solvent or showering. Then, it is sufficiently dried.
  • the obtained stretched sheet is subjected to heat setting and heat treatment.
  • a relaxation operation is performed so that a predetermined relaxation rate is obtained in a predetermined temperature atmosphere.
  • the relaxation operation means that the stretched sheet is M It is an operation to reduce in the D direction and Z or TD direction.
  • the relaxation rate is the value obtained by dividing the MD dimension of the film after the relaxation operation by the MD dimension of the film before the operation, or the value obtained by dividing the TD dimension after the relaxation operation by the TD dimension of the film before the operation, or When both MD and TD are relaxed, the value is the product of the MD relaxation rate and the TD relaxation rate.
  • Specific methods include a method using a tenter or a roll drawing machine.
  • the predetermined temperature is preferably less than 135 ° C.
  • the predetermined relaxation rate is preferably 0.9 or less, and more preferably 0.8 or less, in order to reduce the heat shrinkage rate. Further, in order to prevent the generation of wrinkles and to make the porosity and permeability within the above-mentioned preferable ranges, it is preferably 0.6 or more.
  • the relaxation operation may be performed in both the MD direction and the TD direction, but may be performed only in one direction in the MD direction or the TD direction. Even when the relaxation operation is performed in one direction, it is possible to reduce the heat shrinkage rate not only in the operation direction but also in the direction perpendicular to the operation direction.
  • surface treatment such as electron beam irradiation, plasma irradiation, surfactant coating, chemical modification, etc. can be applied to the surface of the heat-set stretched sheet.
  • the master roll after the heat setting is aged at a predetermined temperature, and then the master roll is rewound. This step releases the residual stress of the polyolefin in the master roll.
  • the heat treatment temperature of the master roll is preferably 35 ° C or higher, more preferably 45 ° C or higher, particularly preferably 60 ° C or higher. Further, 120 ° C. or less is preferable from the viewpoint of maintaining the permeability of the membrane.
  • Plasticizers that can be used in the present invention include organic compounds that can form a homogeneous solution with polyolefin at temperatures below the boiling point, and specifically include decalin, xylene, dioctyl phthalate, dibutyl phthalate, stearyl.
  • Examples include alcohol, oleyl alcohol, decyl alcohol, normal alcohol, diphenyl ether, n -decane, n -dodecane, and paraffin oil. Of these, paraffin oil and dioctyl phthalate are preferable.
  • the proportion of the plasticizer is not particularly limited, but it is preferable to add 20% by weight or more in all layers with respect to the amount of raw material input in each layer in order to keep the porosity of the obtained film in an appropriate range.
  • the content is 90% by weight or less in all layers. More preferably, it is 50 to 70% by weight.
  • the extraction solvent that can be used in the present invention is preferably a poor solvent for polyolefin, a good solvent for plasticizer, and a boiling point lower than the melting point of polyolefin.
  • extraction solvents include hydrocarbons such as n-hexane and cyclohexane, halogenated hydrocarbons such as methylene chloride, 1,1,1 trichloroethane, fluorocarbon, ethanol and isopropanol. And alcohols such as acetone and ketones such as acetone and 2-butanone. Select from among these, and use alone or in combination. These extraction solvents may be regenerated by distillation after extraction of the plasticizer and used again.
  • an anti-oxidation agent in the step (a).
  • the resin is calcined before heating.
  • the concentration of the antioxidant is preferably 0.3 wt% or more, more preferably 0.5 wt% or more, based on the weight of the total polyolefin material. Further, 5.0% or less is preferable, and 3.0% or less is more preferable.
  • Phenol-based acid-detergents which are primary acid-detergents, are preferred as acid-detergents.
  • Secondary anti-oxidation agents can also be used in combination with tris (2,4 di-t-butylphenol) phosphite, tetrakis (2,4-di-t-butylphenol), 1,4,4 Examples thereof include phosphoric acid inhibitors such as biphenylene phosphonite and thio acid inhibitors such as dilauric dithiopropionate.
  • the inside of the mixer or the extruder is replaced with a nitrogen atmosphere, and the mixture is melted while maintaining the nitrogen atmosphere. It is preferable to perform kneading.
  • a battery may be prepared by the following method.
  • the microporous membrane is formed into a vertically long shape having a width of 10 mm to: LOO mm and a length of 200 mm to 2000 mm.
  • the separators are stacked in the order of positive electrode separator, negative electrode separator, or negative electrode separator positive electrode separator, and wound into a circular or flat spiral shape. Further, the wound body is accommodated in a battery can and an electrolyte is injected.
  • the type of the battery in the present invention is not particularly limited, but it is preferably a non-aqueous electrolyte battery from the viewpoint of the affinity between the polyolefin microporous membrane and the electrolyte.
  • a lithium ion battery is more preferable from the viewpoint of providing excellent safety when the microporous membrane of the present invention is used as a separator.
  • the (1) intrinsic viscosity and (11) pore closing temperature were measured for each layer by separating the surface layer and the intermediate layer from the laminated film. The peeling method is described below.
  • a sample was cut into an arbitrary size, and a curing cloth tape manufactured by Sliontec Co., Ltd. was attached to the entire surface of one surface. Attach and pull the crossing tape made of Sliontec Co., Ltd. on a part of the surface layer opposite to the layer on which the crossing tape made by Sliontec Co., Ltd. is applied. The surface layer on the side where the cross tape was not applied to the entire surface was peeled off. Paste Sliontec Co., Ltd.'s curing cloth tape on the entire surface of one side of the peeled laminate. Paste Sliontec Co., Ltd.'s curing cloth tape on a part of the opposite layer. Any layer was peeled off.
  • Mv was calculated according to the following formula.
  • the Mv of the layer was calculated from the polyethylene equation.
  • Porosity (volume mass Z film density) Z volume X 100
  • the film density was calculated at a constant 0.95.
  • the tensile elongation (%) was obtained by dividing the amount of elongation (mm) until the sample broke by the distance between chucks (5 Omm) and multiplying by 100.
  • the tensile strength (MPa) was obtained by dividing the strength at break of the sample by the cross-sectional area of the sample before the test. Also, by summing the MD direction value and the TD direction value, the total (%) of MD tensile elongation and TD tensile elongation was obtained. The measurement was performed at a temperature of 23 ⁇ 2 ° C, a chuck pressure of 0.30 MPa, and a tensile speed of 200 mmZ (for a sample where the distance between chucks cannot be secured to 50 mm, the strain rate is 400% Z). [0052] (7) Melting point
  • Measurement was performed using DSC-220C manufactured by Seiko Ichi Kogyo Co., Ltd.
  • the sample was punched into a circle with a diameter of 5 mm, and several sheets were stacked to make 3 mg. This was spread on an aluminum open sample pan with a diameter of 5 mm, a crimping cover was put on, and it was fixed in the aluminum pan with a sample sealer.
  • the temperature from 30 ° C to 180 ° C was measured at a rate of temperature increase of 10 ° CZmin, and the temperature at which the melting endotherm curve was maximized was taken as the melting point.
  • the polyolefin microporous film After making the polyolefin microporous film into a thickness of about 1 mm using a heating press, it was measured with an infrared spectrophotometer (FTS60AZ896ZU MA300 manufactured by Varian Technologies Japan Limited). Absorbance at 910 cm _1, the density of the polyolefin microporous film (g / cm3) and the thickness of the sample from (mm), POLYMER LETTERS
  • VOL. 2, PP. 339-341 Referring to the concentration of terminal bur groups, that is, the number of terminal bur groups per 10,000 carbon atoms in polyethylene (hereinafter this unit is expressed in units of Zio, 000C). (Expressed) was calculated from the following equation. The calculation was performed by rounding down the decimals.
  • the unit of density is gZcm 3 and the unit of thickness is mm.
  • a sample cut to 100 mm in the MD direction and 100 mm in the TD direction was left in an oven at 130 ° C for 1 hour. At this time, it was sandwiched between two sheets of paper so that the sample was not directly exposed to the hot air. After removing from the oven and cooling, the length (mm) was measured, and the thermal shrinkage of MD and TD was calculated by the following formula.
  • Fig. 1 (A) shows a schematic diagram of a device for measuring the hole closing temperature.
  • 1 is a microporous film
  • 2A and 2B are 10 m thick nickel foil
  • 3A and 3B are glass plates.
  • 4 is an electric resistance measuring device (LCR meter “AG-4311” (trademark) manufactured by Ando Electric Co., Ltd.), which is in contact with nickel foils 2A and 2B. It has been continued.
  • 5 is a thermocouple connected to a thermometer 6.
  • a data collector 7 is connected to the electrical resistance measuring device 4 and the thermometer 6. 8 is an oven in which the microporous membrane was heated.
  • the microporous membrane 1 was superposed on the nickel foil 2A, and this was fixed to the nickel foil 2A with “Teflon” (registered trademark) tape (shaded portion in the figure) in the vertical direction.
  • "Teflon” (registered trademark) tape is pasted onto nickel foil 2mm, leaving a 15mm x 10mm window part in the center of foil 2mm. Masked.
  • Nickel foil 2A and nickel foil 2B were superposed so as to sandwich microporous film 1, and two nickel foils were sandwiched between glass plates 3A and 3B. At this time, it was arranged so that the window portion of the foil 2B and the porous membrane 1 were at opposite positions.
  • thermocouple 5 was fixed to the glass plate with “Teflon” (registered trademark) tape.
  • PVDF polyvinylidene as a binder one mold - isopropylidene
  • NMP N-methylpyrrolidone
  • This slurry was applied to one side of a 20 / zm thick aluminum foil serving as a positive electrode current collector with a die coater, dried at 130 ° C. for 3 minutes, and then compression molded with a roll press.
  • the amount of active material applied to the positive electrode was 250 gZm 2 and the bulk density of the active material was 3.OOgZcm 3 . This was cut to a width of about 40 mm to form a strip.
  • Electrode plate laminate The above microporous membrane separator, strip-shaped positive electrode, and strip-shaped negative electrode were stacked in the order of the strip-shaped negative electrode, separator, strip-shaped positive electrode, and separator, and wound in a spiral shape to produce an electrode plate laminate.
  • This electrode plate laminate is pressed into a flat plate shape and then housed in an aluminum container.
  • the aluminum lead derived from the positive electrode current collector force is placed on the container wall, and the nickel lead derived from the negative electrode current collector is placed on the container lid terminal. Connected to the department.
  • the lithium-ion battery thus fabricated was 6.3 mm in length (thickness), 30 mm in width, and 48 mm in height.
  • the battery was charged to V, and then the current value was started to be reduced so as to hold 4.2 V.
  • the temperature was raised to 0 ° C at a rate of 5 ° CZ and left at 150 ° C for 1 hour.
  • a microporous membrane consisting of two surface and intermediate layers with the same composition was made.
  • the composition of the surface layer is as follows: [7?] Is 1.2 dlZg, Mv is 70,000, 45% by weight of homopolymer polyethylene with a melting point of 133 ° C, [7?] Is 2.8 dlZg, Mv is 250,000, and the melting point is The homopolymer polyethylene was 45 wt% at 136 ° C, [7?] ⁇ 4.9 dlZg, and the homopolymer polypropylene was 5 wt% with Mv 400,000.
  • the intermediate layer has a [7?] Force of 6dlZg, Mv of 700,000 and a homopolymer polyethylene with a melting point of 135 ° C of 46.5 wt%, [7?] 2.8dlZg, Mv Power 250,000, 136.
  • the homopolymer polyethylene of C was 46.5 wt%, [7?] 4.9 dl / g, and the homopolymer polypropylene of Mv 400,000 was 7 wt%.
  • Each of these yarns was blended.
  • As an antioxidant 0.3 wt% tetrakis (methylene 3- (3,5,1-di-tert-butyl 4'-hydroxyphenol) propylene) methane was mixed with the total polymer in each layer.
  • This sheet was stretched 7 ⁇ 4 times with a simultaneous biaxial stretching machine at 124 ° C. Thereafter, this stretched sheet was immersed in methylene chloride, and the fluid paraffin was extracted and dried, followed by heat treatment at 120 ° C. to obtain a microporous membrane.
  • the physical properties of the obtained microporous membrane are shown in Tables 1 and 2.
  • the composition of the surface layer is 50 wt% of homopolymer polyethylene with [7?] Of 1.2 dlZg, Mv of 70,000 and melting point of 133 ° C, and [7?] Force of .8dlZg, Mv of 250,000 and melting point.
  • a microporous membrane was prepared in the same manner as in Example 1 except that the homopolymer polyethylene at 136 ° C. was changed to 50 wt%.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • a microporous membrane consisting of two surface and intermediate layers with different compositions was produced.
  • the composition of the surface layer on one side is: [r?] Is 1.2 dlZg, Mv is 70,000, homopolymer polyethylene 50wt% with a melting point of 133 ° C, [7?] Is 2.8dlZg, Mv is 25 Homopolymer with a melting point of 136 ° C is 50 wt% of polyethylene.
  • Liquid paraffin (37.78 ° C kinematic viscosity 75.90cSt) 50wt% was injected into each extruder from the side feed.
  • the composition of the surface layer on the opposite side is as follows: [r?] Is 1.2 dl / g, Mv is 70,000, 50 wt% of homopolymer polyethylene with a melting point of 133 ° C, [] force. 8 dl / g, Each surface layer is 30 wt% of a homopolymer with an Mv of 250,000 and a melting point of 136 ° C, and a homopolymer of 20 wt% with an [r?] Of 5.6 dlZg, an Mv of 700,000 and a melting point of 135 ° C.
  • a microporous membrane was formed in the same manner as in Example 1 except that 65 wt% of liquid paraffin (37.78 ° C kinematic viscosity 75.90 cSt) was injected into the surface layer extruder from the side feed with respect to 35 wt% of the polymer. Produced.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • a microporous membrane was prepared in the same manner as in Example 2 except that the thickness of the sheet was 0.7 mm. Tables 1 and 2 show the physical properties of the prepared microporous membrane.
  • the composition of the surface layer is as follows: [7?] Is 1.7 dlZg, Mv is 120,000, the copolymer is 50 wt% of polyethylene with a melting point of 127 ° C, [7?] Is 2.8 dlZg, Mv is 250,000, and the melting point is A microporous membrane was prepared in the same manner as in Example 3 except that 50 wt% of the homopolymer polyethylene at 136 ° C. was used and the heat treatment temperature was 117 ° C. The physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • a microporous membrane was prepared in the same manner as in Example 2 except that the thickness of the sheet was 1.3 mm and the sheet was stretched 7 ⁇ 7 times with a simultaneous biaxial stretching machine.
  • the physical properties produced are shown in Tables 1 and 2.
  • composition of the surface is 75 dl% of homopolymer polyethylene with [7?] 1.2 dlZg, Mv 70,000 and melting point 133 ° C, [7?] 2.8 dlZg, Mv 250,000, melting point
  • a microporous membrane was prepared in the same manner as in Example 5 except that homopolymer polyethylene at 136 ° C. was changed to 25 wt%.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • the surface layer is composed of yarn, [7?] Is 1.2dlZg, Mv is 70,000, homopolymer polyethylene 50wt% with melting point 133 ° C, [7?] Is 2.8dlZg, Mv is 250,000 30 wt% homopolymer polyethylene with a melting point of 136 ° C, [7?] Is 5.6dlZg, Mv is 700,000, and the melting point is 135 ° C. Except for injecting 65 wt% liquid paraffin (37.78 cC kinematic viscosity 75.90 cSt) into the surface layer extruder from the side layer feed with 20 wt% homopolymer 20 wt%.
  • a microporous membrane was prepared as in 5. Tables 1 and 2 show the properties of the prepared microporous membrane.
  • the composition of the surface layer is as follows: [r?] Is 3.2 dlZg, Mv 300,000, melting point is 136 ° C, terminal bur group concentration is 10 ZlO, OOOC 50 wt% homopolymer polyethylene, [7?] 2
  • a microporous membrane was prepared in the same manner as in Example 5, except that 50 wt% of homopolymer polyethylene having an Odl / g, Mvl of 50,000, and a melting point of 133 ° C. was used.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • the composition of the intermediate layer is [7?] 11.3 dlZg, Mv 2 million, 30 wt% of homopolymer polyethylene with melting point 135 ° C, [7?] Force 2. 8 dlZg, Mv 250,000, 70 wt% homopolymer polyethylene with a melting point of 136 ° C, and 65 wt% liquid paraffin (kinematic viscosity at 37.78 ° C 75.90 cSt) from the side feed to the intermediate layer 35 wt%
  • a microporous membrane was prepared in the same manner as in Example 5 except that the microporous membrane was injected into the extruder. Tables 1 and 2 show the physical properties of the fabricated microporous membrane.
  • the composition of the intermediate layer is [7?] 13. ldl / g, Mv 2.5 million, 20 wt% homopolymer polyethylene with melting point 135 ° C, [7?] 5.6 dlZg, Mv 700,000 15 wt% of homopolymer polyethylene with a melting point of 135 ° C, 30 wt% of homopolymer polyethylene with a melting point of 136 °C, 2.8 dlZg, Mv of 250,000 ] Is 1.7 dlZg, Mvl 20,000, melting point 131 ° C, ethylene propylene copolymer (comonomer: prepylene, content ratio 0.6 mol%) is 30 wt%, and liquid paraffin is used for 35% of the intermediate layer polymer.
  • Example 12 The intermediate layer is composed of 15 wt% of a molecular weight of 10,000 or less, MwZMn is 43, [] is 5.6 dlZg, Mv is 700,000, and a homopolymer polyethylene having a melting point of 137 ° C is 80 wt%.
  • a microporous membrane was prepared in the same manner as in Example 5 except that the homopolymer polypropylene of ⁇ 400,000 and [] was 4.9 dlZg and 20 wt%. The physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • the composition of the surface layer is as follows: [7?] Is 1.2dlZg, Mv is 70,000, homopolymer polyethylene 45wt% with melting point 133 ° C, [7?] Is 2.8dlZg, Mv is 250,000, melting point
  • the intermediate layer is 45 wt% of homopolymer with a temperature of 136 ° C and [7?] 4.9 dlZg, and the Mv400,000 homopolymer polypropylene is 5 wt%.
  • Example 5 and Example 5 except that the homopolymer polyethylene with an Mv of 210,000 and a melting point of 136 ° C is 95 wt%, and [7?] 9 dlZg and the homopolymer polypropylene with an Mv of 400,000 is 5 wt%.
  • make a microporous membrane Made The physical properties of the prepared microporous membrane are shown in Tables 1 and 2.
  • the composition of the surface is 75 dl% of homopolymer polyethylene with [7?] 1.2 dlZg, Mv 70,000 and melting point 133 ° C, and [7?] Force. 8dlZg, Mv 250,000 with melting point 136
  • a microporous membrane was prepared in the same manner as in Comparative Example 1 except that the polyethylene was 25 wt% of the homopolymer at ° C and the sheet thickness was 2. Omm.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2. As a result of the battery evaluation, the oven test proved to be satisfactory.
  • a microporous membrane was prepared in the same manner as in Comparative Example 2, except that the thickness of the sheet was 0.7 mm and the sheet was stretched 7 ⁇ 4 times with a simultaneous biaxial stretching machine.
  • the physical properties of the prepared microporous membrane are shown in Tables 1 and 2. As a result of battery evaluation, good results were not obtained in the oven test and the crash test.
  • the composition of the surface layer is [7?] 5.6 dlZg, Mv is 700,000 and the melting point is 135 ° C.
  • the homopolymer polyethylene is 100 wt%, and liquid paraffin (37.78 ° C)
  • a microporous membrane was prepared in the same manner as in Example 5 except that 70 wt% was injected into the surface layer extruder by side feed. Tables 1 and 2 show the physical properties of the fabricated microporous membrane.
  • the composition of the surface layer is [7?] 1.7 dlZg, Mv is 120,000, and the copolymer has a melting point of 125 ° C, 50 wt% of polyethylene, [7?] Force. 8 dlZg, Mv is 250,000, and the melting point is 136.
  • a microporous membrane was prepared in the same manner as in Example 5 except that 50% by weight of the homopolymer polyethylene at ° C, the temperature of the biaxial stretching machine was 121 ° C, and the heat treatment temperature was 115 ° C. Tables 1 and 2 show the physical properties of the fabricated microporous membrane.
  • Example 2 2.1 135 '4.3 140
  • Example 3 2.1 / 2.8 135 4.3 140
  • Example 4 2.1 135 4.3 140
  • Example 5 2.3 131 4,3 140
  • Example 6 2.1 135 4.3 140
  • Example 7 1.7 135 4.3 '140
  • Example 8 2.8 136 4.3 140
  • Example 9 2.3 135 4.3 140 .
  • Example 10 2.1 135 6.0 139
  • Example 12 2.1 135 5.3 138
  • Example 13 2.1 135 5.7 134 Comparative Example 1 2.2 135, 2.5 139 Comparative Example 2 1.7 134 2.5 139 Comparative Example 3 1.7 '134 2.5 139
  • the present invention relates to a microporous membrane used for separation of substances, a selective permeation separation membrane, a separator, and the like, and is particularly suitably used as a separator for lithium ion batteries and the like.
  • Fig. 1 shows a schematic diagram of an apparatus for measuring the pore closing temperature of a microporous membrane of the present invention.

Abstract

La présente invention concerne un film microporeux polyoléfinique correspondant à un stratifié composé d'au moins trois couches dont deux couches superficielles et au moins une couche intermédiaire. Le film se caractérise en ce que la viscosité intrinsèque [η] de la couche intermédiaire est supérieure ou égale à 3,0 dl/g, la viscosité intrinsèque [η] des couches superficielles est inférieure à la viscosité intrinsèque [η] de la couche intermédiaire et en ce que la valeur absolue de l'écart entre la température de fermeture des pores des couches superficielles et celle de la couche intermédiaire est inférieur à 10 °C.
PCT/JP2007/056170 2006-03-30 2007-03-26 Film microporeux polyolefinique WO2007116672A1 (fr)

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JP2018041726A (ja) * 2016-08-31 2018-03-15 旭化成株式会社 蓄電デバイス用セパレータ
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