CN1255460C - Polyolefin microporous membrane - Google Patents

Polyolefin microporous membrane Download PDF

Info

Publication number
CN1255460C
CN1255460C CNB028100751A CN02810075A CN1255460C CN 1255460 C CN1255460 C CN 1255460C CN B028100751 A CNB028100751 A CN B028100751A CN 02810075 A CN02810075 A CN 02810075A CN 1255460 C CN1255460 C CN 1255460C
Authority
CN
China
Prior art keywords
polyethylene
polypropylene
molecular weight
viscosity
average molecular
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
CNB028100751A
Other languages
Chinese (zh)
Other versions
CN1509307A (en
Inventor
迁冈则夫
近藤孝彦
妻藤阳子
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asahi Kasei Corp
Original Assignee
Asahi Kasei Kogyo KK
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 Kogyo KK filed Critical Asahi Kasei Kogyo KK
Publication of CN1509307A publication Critical patent/CN1509307A/en
Application granted granted Critical
Publication of CN1255460C publication Critical patent/CN1255460C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • C08J5/18—Manufacture of films or sheets
    • 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
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • 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
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • 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
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/10—Homopolymers or copolymers of propene
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • H01M6/18—Cells with non-aqueous electrolyte with solid electrolyte
    • H01M6/181—Cells with non-aqueous electrolyte with solid electrolyte with polymeric electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0239—Organic resins; Organic polymers
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Separators (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

A microporous polyolefin film made of a composition is provided, which comprises as essential ingredients (A) polyethylene having a viscosity-average molecular weight of 50,000 to 1,500,000 and (B) polypropylene having a viscosity-average molecular weight of 100,000 to 1,500,000 in such proportions that A+B is at least 80 wt.% based on the whole composition, A/(A+B) is from 51 to 90 wt.%, and B/(A+B) is from 10 to 49 wt.%, and which has a shutdown temperature lower than 140 DEG C and has a continuous phase in which the polyethylene and polypropylene are intertwined with each other.

Description

Polyolefin micro porous polyolefin membrane
Technical field
The present invention relates to polyolefin micro porous polyolefin membrane, in more detail, relate to the polyolefin micro porous polyolefin membrane that is suitable for doing lithium battery separator.
Technical background
All the time, microporous polyethylene film is used as lithium battery separator such as lithium cell, lithium ion battery, lithium polymer battery.
Why mainly using microporous polyethylene film, is the security in order to ensure battery, makes polymer melt stop up communicating aperture at 130 ℃～140 ℃, makes current interruption, and for this reason, polyethylene is fit closely.When using as battery separator, the temperature that preferably opens circuit is low as far as possible.Opening circuit is that the resistance of film increases because the resin that the hole of porous-film is melted stops up, and lithium ion stream is cut off and the phenomenon that produces.
And then, as the mechanical property of dividing plate, require it behind hole plug, still to keep shape invariance, keep interelectrode insulation.Yet, the tendency that polyethylene separator has intensity to reduce after the polymkeric substance fusion.Thereby, how to improve anti-breaking temperature and just become a problem.For example, for guaranteeing the security of battery 150 ℃ the time, in U.S. specification UL1642 " standard of lithium cell ", stipulated in 150 ℃ of baking ovens, to preserve 10 minutes cell safety judgement criteria.For reaching this safety standards, preferred separator more than 150 ℃, is preferably near 160 ℃ of also ruptures of membranes and keep shape invariance not after the atresiaization that opens circuit, and is more preferably the dividing plate of good strength under such high temperature.Also have, under trip condition, the inaccessible hole of a residual part then produces leakage current because ionic leaks if there is complete atresiaization, or because stress concentration and rupture of membranes, so preferred trip temperature lower clapboard is the atresiaization of entirely shutting.
All the time, for attempting to improve the breaking temperature of polyethylene separator, the polypropylene that fusing point is high is mixed in the polyethylene, or attempts using the composite bed of microporous polyethylene film and polypropylene micro-porous film.
The spy open flat 4-126352, spy open flat 4-206257, spy open flat 5-331306, spy open flat 8-92403, and the spy open all to disclose among the flat 9-241411 and contain polyethylene and polyacrylic micro-porous film., wherein disclosed film is all pointed out respectively in an embodiment clearly, all is that the single shaft direction stretches and the micro-porous film made has the intensity of operating direction (MD) and right angle orientation (TD) and the very big tendency of difference of contraction behavior.In addition, because the temperature below poly fusing point is along MD direction stretching perforate, so near polyethylene fused trip temperature, will inevitably significant contraction tendency be arranged along the MD direction.
Te Kaiping-234578, spy open flat 6-96753, and special opening all putting down in writing the dividing plate of forming by specific polyethylene and polypropylene among the flat 6-223802, disclosed preparation method is and sneaks into organic solvent and inorganic powder in polymeric blends, after the extrusion molding, from film, organic solvent and inorganic powder are extracted the method for removing, stretching ratio is low, and draft temperature is also below poly fusing point.
Open 10-298324 and specially flatly open disclosed micro-porous film among the 10-298325 in that the spy is flat, behind the mixture of polyethylene extrusion, polypropylene and solution, the temperature below poly fusing point+10 ℃ stretches and modulates.This film quilt is along biaxial stretch-formed, each is identical to rerum natura, its draft temperature is below polyolefinic fusing point+10 of forming ℃, the preferred scope below crystalline melt point, also have, thermal stable temperature also below fusing point, so the percent thermal shrinkage when opening circuit is very big, how to make low shrinking percentage is arranged near trip temperature, low string stress just becomes a problem.
On the other hand, open among the flat 7-268118, disclose and have the polyacrylic mixing of ultra high molecular polyethylene and supra polymer and form the micro-porous film that obtains by being separated the spy.And disclose by being formed on the being seen crystallization that has the crystallization of 130 ℃～140 ℃ of melting temperature (Tm)s and have 140 ℃～152 ℃ high melting temperature (Tm) usually in the polyethylene, made the method for film intensity increase at high temperature.,, only find that also film strength increases when multipotency reaches 150 ℃, also not have the increase of discovery film toughness in the time of 160 ℃ even in this method.Also have a difficult problem, promptly increase polyacrylic ratio, when polypropylene formed external phase, trip temperature became more than 140 ℃, and after opening circuit, remaining have not closed hole, causes leakage current because ion leaks.Based on this reason, disclosed in this application micro-porous film, the mixture that we consider to use polyolefine and softening agent are prepared from by so-called " phase separation method " as raw material.In phase separation method, arbitrary phase of polyethylene phase, polypropylene phase all forms little porous, increases polyacrylic ratio, and not inaccessible little porous of polyethylene fusion back polypropylene phase increases.Have again, all can be very difficult owing to open the spy that the very big and softening agent of the molecular weight of the polymkeric substance of putting down in writing among the flat 7-268118 mixes or push.
Summary of the invention
The present invention relates to become the polyolefin separator of main component with polyethylene and polyacrylic combined group, for with single corresponding trip temperature of forming by polyethylene of dividing plate, preferably less than 140 ℃, be more preferably trip temperature less than 138 ℃, and, low shrinking percentage is arranged under trip temperature, entirely shut after opening circuit, do not have little porous residual and can not cause the leakage of electric current, and film strength is very high when high temperature, provides to be suitable for the micro-porous film of lithium cell with dividing plate.
The present invention is as follows:
(1) a kind of polyolefin micro porous polyolefin membrane, the indispensable composition that contains is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, consisting of of this polyolefin micro porous polyolefin membrane: A+B accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is 10～49wt%, trip temperature forms the external phase that polyethylene and polypropylene are twining mutually less than 140 ℃.
(2) a kind of polyolefin micro porous polyolefin membrane, the indispensable composition that contains is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, it consists of A+B and accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is 10～49wt%, and trip temperature is less than 140 ℃ polyolefin micro porous polyolefin membrane, and the shock strength during with this film trip temperature is made as F1, shock strength in the time of 160 ℃ is made as F2, then F1 〉=1g/ μ m and F2/F1 〉=0.2.
(3) as the polyolefin micro porous polyolefin membrane of record in above-mentioned (1) or (2), it is characterized in that,
1) percent thermal shrinkage under the trip temperature is below 30%;
2) thickness is that 5 μ m are to 50 μ m;
3) voidage is from 30% to 80%, and
4) the normal temperature shock strength is more than the 5g/ μ m.
(4) manufacture method of micro-porous film, the indispensable composition that will contain is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, and consisting of A+B accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is that the composition of 10～49wt% is sheared, melting mixing, extruding, make presoma with external phase that polyethylene and polypropylene twining mutually, this presoma stretches, make the atresia oriented film, by 110～140 ℃ of thermal treatments, form little porous then.
(5) lithium cell dividing plate is by each micro-porous film of putting down in writing formation of above-mentioned (1)～(3).
Description of drawings
Fig. 1 is the sketch of the test set of trip temperature and short circuit temperature.
Fig. 2 is the part figure of the test set of trip temperature and short circuit temperature.
Fig. 3 is the part figure of the test set of trip temperature and short circuit temperature.
Embodiment
As mentioned above, the existing a plurality of records of prior art that utilize polyethylene and polypropylene to mix and make micro-porous film, but also do not provide trip temperature low so far, the shrinking percentage during trip temperature is little, even do not have the electric current leakage after opening circuit and also keep high-intensity micro-porous film at 160 ℃ high temperature.This is the reason owing to polyethylene and polyacrylic phase structure and hole structure.Promptly, because polyethylene and the normally immiscible polymkeric substance of polypropylene, when preparing with in the past preparation method, the polymkeric substance that ratio is high is external phase (sea), the polymkeric substance that ratio is low is discontinuous phase (island), forms so-called island structure, in the micro-porous film of the island structure that forms, can not have low trip temperature simultaneously, high strength under the high temperature and the low-shrinkage under the high temperature.
In a word, poly ratio height, when polyethylene was external phase, the temperature more than the polyethylene fusing point, film strength had reduction trend.This is because the high polypropylene of fusing point is in dispersion state, can not gain in strength.On the other hand, polyacrylic ratio height, when polypropylene is external phase, the temperature more than the polyethylene fusing point, film strength will raise, but at this moment trip temperature will uprise.This is that polyacrylic melting temperature (Tm) becomes big cause to the inaccessible influence in hole owing to increase polyacrylic ratio.In the present invention, make polyethylene and polypropylene form the external phase of mutual winding, even temperature is more than poly fusing point, also has high intensity, and by only making the mutually little porous of polyethylene, this film can not rely on polyacrylic ratio, opens circuit when the polyethylene fusion and closure.
Below micro-porous film of relevant polyolefin series of the present invention and preparation method thereof is described in detail.
As the polyethylene that uses in the present invention, preferred middle density and/or high density polyethylene(HDPE) can also use homopolymer, oligopolymer, or graftomer.Particularly as maleic anhydride grafted polyethylene, when being used to dividing plate, owing to improved wettability with electrolytic solution, thus very good effect is arranged.The molecular weight of the polyethylene that is used (during two or more mixing mixed polyethylene) considers that from intensity preferred viscosity-average molecular weight is more preferably more than 200,000 more than 50,000.In addition, be different from viscosity-average molecular weight, preferable weight-average molecular weight is more than 50,000.Perhaps, preferred viscosity-average molecular weight is more than 50,000, and weight-average molecular weight is more than 50,000, be more preferably viscosity-average molecular weight more than 200,000, and weight-average molecular weight is more than 50,000.Polyethylene can use one or more.When viscosity-average molecular weight was used alone or as a mixture at the ultra high molecular polyethylene more than 500,000, the rerum natura of film is very good then.Also have, consider that from carrying out homogeneous phase melting mixing aspect preferred viscosity-average molecular weight is below 1,500,000, and weight-average molecular weight is below 2,000,000.The polyethylene that uses among the present invention is but that molecular weight is higher in the mixing scope of homogeneous phase, and this is beneficial to and forms the dystectic extended-chain crystal with High-Temperature Strengthening effect.
In a word, Te Kaiping 5-234578, spy open that flat 6-96753, spy open flat 6-223802, the spy opens among the flat 7-268118, add organic solvent (softening agent) in order to be separated, even use the polyethylene of ultra-high molecular weight, also be difficult to generate dystectic long extended-chain crystal with High-Temperature Strengthening effect.The present invention has not with an organic solvent under the situation, and super drawing easily forms the advantage of extended-chain crystal easily.Relevant therewith, open among the flat 7-268118 the spy, poly limiting viscosity [η] is disclosed if do not reach 10dl/g (viscosity-average molecular weight is about 1,600,000), just can not form dystectic extended-chain crystal, and formed in the present invention micro-porous film, viscosity-average molecular weight is about 200,000, can generate dystectic extended-chain crystal.Also has the dystectic extended-chain crystal of the high more easy more generation of molecular weight.The external phase of twining under the non-shear field, keeps pyritous to become discontinuous phase simultaneously, but uses high molecular viscosity high more mutually, and transformation time is long more, and external phase more is easy to get.
Do not limit the polyacrylic kind of use among the present invention, can exemplify isotatic polypropylene, Atactic Polypropelene, propylene ethylene copolymers, 1-butylene propylene copolymer etc., wherein preferably contain the polypropylene of 90% above isotactic index.Also have, the viscosity-average molecular weight of employed polypropylene (polypropylene of being sneaked into during two or more mixing) is preferably more than 100,000.On the other hand, different with viscosity-average molecular weight, weight-average molecular weight is preferably more than 100,000.Have, from carrying out the viewpoint of homogeneous phase melting mixing, preferred viscosity-average molecular weight is below 1,500,000 again.When using polypropylene copolymer, the crystallization melting temperature (Tm) is preferably more than 160 ℃.
In the composition of micro-porous film, require polyethylene and polypropylene to account for more than the whole 80wt%.As other composition, can also add for example inorganics such as aluminum oxide or montmorillonite in right amount, the polymkeric substance beyond polyethylene, the polypropylene, and antioxidant.
Employed polyethylene and polyacrylic ratio are considered from voidage, the High-Temperature Strengthening effect aspect of micro-porous film, must be that polyethylene accounts for 51～90wt%, and polypropylene accounts for 10～49wt%.
One of feature of micro-porous film among the present invention is, although polypropylene is lower than poly ratio of mixture, also forms the external phase of twining mutually with polyethylene.Because polypropylene forms external phase,, also has good shock strength even then under 160 ℃ high temperature.
Whether whether the polypropylene that mixture ratio is little forms external phase, can have strengthening effect to judge by measuring film strength on poly crystal melting temperature (Tm) in the temperature range below the polyacrylic crystal melting temperature (Tm).Also have, also can judge by the transmission electron microscope photo of ultrathin section(ing).
Polyethylene and polyacrylic mixed system are normally immiscible, in the shear field, because the rising of phase separation temperature, according to selected specified temp and shear-stress, (detailed content is with reference to great by well to access the homogeneous phase dissolved state, the plastics epoch (プ ラ ス チ Star Network エ-ジ), in June, 2000, p131～137).Said in the shear field melting mixing, mix with regard to being to use big biaxial extruder to wait and finishing.Melting mixing among the application's the preparation method also comprises, adds necessary composition or the 3rd kind of composition from the intermediary side import of forcing machine.
In device such as biaxial extruder, the composition of melting mixing is by laminated dies such as grooved mould and T patterns, or circular mode such as spiral pattern and rotation pattern are extruded.Because when stopping to shear, the external phase through twining mutually earlier that is separated of homogeneous system reaches discontinuous phase again, so after stopping to shear, preferably cooling curing solidifies external phase.In mould, behind the cooling curing, can extrude with the solid phase extrusion process.
Presoma is that all shapes such as laminar, film like, tubulose all have no relations.The presoma of extruding is drawn into plane or tubulose, makes non-porous film.As planar stretch, be divided into single shaft or biaxial stretch-formed, biaxial stretch-formed from the aspect such as tropism such as grade of rerum natura for well, can use biaxial stretch-formed successively and simultaneously biaxial stretch-formed.Draft temperature is considered from the film toughness aspect, preferably adopts 100 ℃～160 ℃ scope, is more preferably 130 ℃～150 ℃.If reduction draft temperature, film strength become big, and near the contraction trip temperature becomes big.After also can adopting cryogenic tensile, heat setting under the high temperature.For being implemented in percent thermal shrinkage low under the trip temperature, in stretching or heat setting technology, preferably be controlled at more than the poly crystallization melting temperature (Tm).
Film after the stretching owing to be at 100 ℃～150 ℃, be preferably in 110 ℃～140 ℃ following thermal treatments and realize forming porous preferably less than 140 ℃, is more preferably less than the little porous that opens circuit under 138 ℃.By heat treated perforate, for example dissolve low-melting polyethylene part selectively or under molten state with after the film thermal treatment, use and this liquid mixes and do not clean in the washing composition of polyethylene dissolving, remove this liquid after drying and can make.In order to prevent the contraction of film, preferably under air-tight state, heat-treat.By present method perforate, little porous is to divide in polyethylene portions to form.Whether little porous is mainly divided in polyethylene portions and is formed, can be by after the micro-porous film heat treated being made it to open circuit under less than 140 ℃, whether measure has leakage current, or with electron microscope observation on the surface and section whether have not the hole of obturation judge.As being used for heat treated liquid, can in paraffin wet goods hydrocarbon polymer, fatty alcohol, aliphatic ketone, organic compounds containing nitrogen, ether, ethylene glycol, aliphatic ester, silicone oil etc., be used alone or in combination.Thermal treatment temp height then heat treatment time is short.The intensity that be to keep the resin after the porous, the treatment time is short in well.Also have,, can use ketones solvents such as chlorinated solvents such as fluorine-containing organic solvent, methylene dichloride, methylethylketone such as lower boiling hydrocarbon polymer, fluorine-containing ether or hydrofluoric ether such as hexane as the cleaning solvent after the thermal treatment.
Followingly do explanation in further detail according to embodiment.
Experimental technique shown in the embodiment is as follows
(1) thickness
With dial ga(u)ge (the rugged making of tail institute: test PEACOCK No.25)
(2) porosity
Get the sample at 20cm angle,, be calculated as follows by volume and quality.
Porosity (%)=(volume (cm 3The density of)-quality (g)/component of polymer)/volume (cm 3) * 100
(3) normal temperature shock strength
Use the portable compression tester of KES-G5 of カ ト one テ Star Network corporate system,, carry out impact experiment under the condition of impact velocity 2mm/sec, measure maximum impact load (g) at the radius-of-curvature 0.5mm of needle point.Measured value be multiply by 1/ thickness (μ m), just be converted into the shock strength of 1 μ m.
(4) high temperature impact intensity
Micro-porous film is clipped in two internal diameter 13mm, in the packing ring of the stainless steel of external diameter 25mm, with clip fixing around behind 4 points, in the trip temperature of film, and be immersed in 160 ℃ silicone oil (SHIN-ETSU HANTOTAI's chemical industry: KF-96-10CS) after 30 seconds, with and (3) same method measure shock strength.
(5) percent thermal shrinkage
Micro-porous film was placed 1 hour under the atmosphere of trip temperature, tried to achieve the variation of MD direction, each direction length of TD direction.The percent thermal shrinkage of each sample uses the maximum value of MD, TD.
(6) trip temperature
Fig. 1 is the sketch of trip temperature measuring apparatus.The 1st, micro-porous film, 2A and 2B are that thickness is the nickel foil of 10 μ m, and 3A and 3B are sheet glass.The 4th, resistance measurement device (peace rattan electrical equipment system LCR メ one one AG-4311) is connected with nickel foil 2A, 2B.The 5th, thermopair is connected with thermometer 6.The 7th, data gathering system is connected with resistance device 4 and thermometer 6.The 8th, baking oven is used to heat micro-porous film.
Illustrate in greater detail, as shown in Figure 2, micro-porous film is superimposed upon on the nickel foil 2A, be fixed on the nickel foil 2A with teflin tape in the vertical.Micro-porous film 1 is immersed in the anti-fluorizated lithium solution (solvent: trimethylene carbonic ether/vinyl carbonate/gamma-butyrolactone=1/1/2) of 1mol/l.As shown in Figure 3, be adjacent on the nickel foil 2B, leave the window portion of 15mm * 10mm in the centre of nickel foil 2B with teflin tape.
With nickel foil 2A and 2B micro-porous film 1 is clipped, and then be clipped in the both sides of nickel foil with sheet glass 3A, 3B.At this moment, the window portion of nickel foil 2B is in relative position with porous-film 1.Two sheet glass are to use commercially available two-sided clip fixed.With teflin tape thermopair 5 is fixed on the sheet glass.
Adopt said apparatus METHOD FOR CONTINUOUS DETERMINATION temperature and resistance.With the speed of 2 ℃/min temperature is elevated to 200 ℃ from 25 ℃, resistance is measured under the interchange of 1kHz.The resistance that so-called trip temperature is defined as when micro-porous film reaches 10 3Temperature during Ω.
(7) viscosity-average molecular weight
Determination limit viscosity [η] in 135 ℃ naphthalane solution calculates viscosity-average molecular weight (Mv) by following formula.Or limiting viscosity is according to [polymer analysis handbook] (P58), determines by viscosimetry.
[η]＝6.77×10 -4Mv 0.67
Embodiment 1
With high density polyethylene(HDPE) (density 0.95, viscosity-average molecular weight 280,000) 75 weight parts, polypropylene (density 0.90, viscosity-average molecular weight 250,000) 25 weight parts, and with respect to said composition be 0.3 weight part antioxidant four-[3-(3 ', 5 '-di-t-butyl-4 '-hydroxy phenyl) propionic acid] pentaerythritol ester, the biaxial extruder that with bore is 30mm, L/D=48 is mixing under 230 ℃, the condition of 500rpm, after from the T pattern that is arranged on the forcing machine front end, being extruded, cooling curing on 25 ℃ of refrigerative casting rolls forms the thick thin slice of 0.5mm immediately.
With this thin slice 135 ℃ carry out down 7 * 7 times stretching with biaxial stretch-formed machine simultaneously after, be fixed on the support, be immersed in 130 ℃ the paraffin oil 2 minutes, promptly obtain micro-porous film with the methylethylketone cleaning then.
The rerum natura of resulting micro-porous film is illustrated in table 1.Even under 160 ℃, also found goodish high temperature impact intensity, can confirm that polypropylene forms external phase mutually, film after stretching can also be dyeed with ruthenium,, can be observed polyethylene forms mutual winding mutually mutually with polypropylene external phase by the transmission electron microscope observation ultrathin section(ing).
Embodiment 2
With high density polyethylene(HDPE) (density 0.94, viscosity-average molecular weight 1,000,000) 75 weight parts, polypropylene (density 0.90, viscosity-average molecular weight 250,000) 25 weight parts, and with respect to said composition be 0.3 weight part antioxidant four-[3-(3 ', 5 '-di-t-butyl-4 '-hydroxy phenyl) propionic acid] pentaerythritol ester, the biaxial extruder that with bore is 30mm, L/D=48 is mixing under 240 ℃, the condition of 500rpm, after being extruded from the T pattern that is arranged on the extrusion machine front end, cooling curing on 25 ℃ of refrigerative casting rolls forms the thick thin slice of 0.5mm immediately.
With this thin slice 135 ℃ carry out 7 * 7 times stretching with biaxial stretch-formed machine simultaneously after, be immersed in 130 ℃ the paraffin oil 2 minutes, clean with methylethylketone then and promptly obtain micro-porous film.The rerum natura of resulting micro-porous film is illustrated in table 1.
Comparative example 1
With high density polyethylene(HDPE) (density 0.95, viscosity-average molecular weight 280,000) 75 weight parts, polypropylene (density 0.90, viscosity-average molecular weight 250,000) 25 weight parts, and with respect to said composition be 0.3 weight part antioxidant four-[3-(3 ', 5 '-di-t-butyl-4 '-hydroxy phenyl) propionic acid] pentaerythritol ester, use batch-type mixer (the smart machine-processed ラ ボ プ ラ ス ト ミ Le of Japan) mixing under 250 ℃, the condition of 5rpm, the mixing thing of gained kept 10 minutes at 200 ℃ thermocompressor, formed the thick thin slice of 0.5mm.
With this thin slice 135 ℃ carry out 7 * 7 times stretching with biaxial stretch-formed machine simultaneously after, be immersed in 130 ℃ the paraffin oil 2 minutes, clean with methylethylketone then and promptly obtain micro-porous film.The rerum natura of resulting micro-porous film is illustrated in table 1.
Have again, the film after stretching with transmission electron microscope observation, can observe with the polypropylene of 5～10 μ m is the island shape structure on island.
Comparative example 2
With high density polyethylene(HDPE) (density 0.95, viscosity-average molecular weight 280,000) 75 weight parts, polypropylene (density 0.90, viscosity-average molecular weight 250,000) 25 weight parts, and with respect to said composition be 0.3 weight part antioxidant four-[3-(3 ', 5 '-di-t-butyl-4 '-hydroxy phenyl) propionic acid] the pentaerythritol ester mixing, use feeder to render in the biaxial extruder of bore as 30mm, L/D=48.Using the side feeder then is that 100% mobile paraffin (37.78 ℃ dynamic viscosity is 75.9cSt) is injected in the forcing machine with weight percent, mixing under 230 ℃, the condition of 500rpm, after being extruded from the T pattern that is arranged on the forcing machine front end, the same with embodiment 1, cooling curing on 25 refrigerative casting rolls forms the thick thin slice of 1mm immediately.
With this thin slice 120 ℃ carry out 7 * 7 times stretching with biaxial stretch-formed machine simultaneously after, stretched film is immersed in the methylethylketone, the paraffin of liquid state is removed, promptly obtain micro-porous film after the drying.
The rerum natura of resulting micro-porous film is illustrated in table 1.With the film after the transmission electron microscope observation stretching, can observe polypropylene and be dispersed in mutually in the poly external phase, present island shape structure.
In trip temperature test, trip temperature not only reaches 142 ℃, and the resistance during just to trip temperature is unsettled.As if the micro-porous film that has just arrived trip temperature with transmission electron microscope observation, can find to have during polypropylene mutually not inaccessible pore structure.
Embodiment 1 Embodiment 2 Comparative example 1 Comparative example 2
The method of mixing Biaxial extruder Biaxial extruder Mixing roll Biaxial extruder
Velocity of shear High-shear High-shear The low shearing High-shear
Raw material is formed * PE/PP PE/PP PE/PP PE/PP/solvent
Thickness μm 20 18 22 20
Voidage ％ 57 47 59 40
The normal temperature shock strength g 310 610 220 400
The normal temperature shock strength of 1 μ m g/μm 15.5 33.9 10.0 20.0
Shock strength during trip temperature g 65 137 62 29
F1 g/μm 3.3 7.6 2.8 1.45
Shock strength in the time of 160 ℃ g 23 31 3 150 ℃ of ruptures of membranes
F2 g/μm 1.2 1.7 0.1 -
F2/F1 0.36 0.22 0.05 -
Trip temperature ℃ 131 133 131 142
Percent thermal shrinkage during trip temperature ％ 18 20 15 33
PE: polyethylene
PP: polypropylene
Industrial applicibility
Micro-porous film among the present invention has good elevated temperature strength concurrently and low trip temperature reaches shrinkage factor low when trip temperature, is particularly suitable for doing the dividing plate in the lithium battery.

Claims (5)

1. polyolefin micro porous polyolefin membrane, the indispensable composition that contains is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, it consists of: A+B accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is 10～49wt%, it is characterized in that, trip temperature is less than 140 ℃, polyethylene wherein is the external phase of twining mutually with polypropylene mutually mutually, and only makes the mutually little porous of polyethylene.
2. polyolefin micro porous polyolefin membrane, the indispensable composition that contains is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, it consists of A+B and accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is 10～49wt%, trip temperature is less than 140 ℃ polyolefin micro porous polyolefin membrane, it is characterized in that, make polyethylene form mutual external phase of twining mutually with polypropylene mutually, and only make the mutually little porous of polyethylene, shock strength during with this film trip temperature is made as F1, and the shock strength in the time of 160 ℃ is made as F2, then F1 〉=1g/ μ m and F2/F1 〉=0.2.
3. according at claim 1 or 2 described polyolefin micro porous polyolefin membranes, it is characterized in that,
1) percent thermal shrinkage under the trip temperature is below 30%;
2) thickness is that 5 μ m are to 50 μ m;
3) voidage is from 30% to 80%, and
4) the normal temperature shock strength is more than the 5g/ μ m.
4. the manufacture method of micro-porous film, the indispensable composition that will contain is that viscosity-average molecular weight is 50,000～1,500,000 the polyethylene (A) and the polypropylene (B) of viscosity-average molecular weight 100,000～1,500,000, and consisting of A+B accounts for more than the whole 80wt%, A/ (A+B) is 51～90wt%, B/ (A+B) is that the composition of 10～49wt% is sheared, melting mixing, extruding, make presoma with external phase that polyethylene and polypropylene twining mutually, this presoma stretches, make the atresia oriented film, by 110～140 ℃ of thermal treatments, only make the mutually little porous of polyethylene then.
5. lithium cell dividing plate is made of each described polyolefin micro porous polyolefin membrane of claim 1～3.
CNB028100751A 2001-05-17 2002-05-16 Polyolefin microporous membrane Expired - Lifetime CN1255460C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP147935/2001 2001-05-17
JP2001147935 2001-05-17

Publications (2)

Publication Number Publication Date
CN1509307A CN1509307A (en) 2004-06-30
CN1255460C true CN1255460C (en) 2006-05-10

Family

ID=18993340

Family Applications (1)

Application Number Title Priority Date Filing Date
CNB028100751A Expired - Lifetime CN1255460C (en) 2001-05-17 2002-05-16 Polyolefin microporous membrane

Country Status (5)

Country Link
JP (1) JP4641706B2 (en)
KR (1) KR100557380B1 (en)
CN (1) CN1255460C (en)
TW (1) TW543224B (en)
WO (1) WO2002092677A1 (en)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI305215B (en) * 2004-08-30 2009-01-11 Asahi Kasei Chemicals Corp Polyolefin microporous membrane and separator for battery
JP5213443B2 (en) * 2005-08-03 2013-06-19 旭化成イーマテリアルズ株式会社 Polyolefin microporous membrane
KR101288803B1 (en) * 2007-09-12 2013-07-23 에스케이이노베이션 주식회사 Microporous polyethylene film with good property of strength and permeability at high temperature
US8338017B2 (en) 2007-10-12 2012-12-25 Toray Battery Separator Film Co., Ltd. Microporous membrane and manufacturing method
JP5403932B2 (en) * 2008-03-31 2014-01-29 旭化成イーマテリアルズ株式会社 Polyolefin microporous membrane
JP4733232B2 (en) * 2008-03-31 2011-07-27 旭化成イーマテリアルズ株式会社 Polyolefin microporous membrane and wound product
JP6659214B2 (en) * 2014-10-17 2020-03-04 トヨタ自動車株式会社 Battery separators, laminated separators, lithium ion secondary batteries and assembled batteries
CN105355811B (en) * 2015-10-29 2018-08-17 乐凯胶片股份有限公司 A kind of MIcroporous polyolefin film, preparation method and lithium ion battery
JP6025958B1 (en) 2015-11-30 2016-11-16 住友化学株式会社 Nonaqueous electrolyte secondary battery separator and use thereof
JPWO2019093184A1 (en) 2017-11-08 2020-11-19 東レ株式会社 Polyolefin composite porous membrane and its manufacturing method, battery separator and battery
JP7207300B2 (en) * 2018-02-23 2023-01-18 東レ株式会社 porous polyolefin film
WO2019190253A1 (en) * 2018-03-28 2019-10-03 주식회사 엘지화학 Method for evaluating stability of separator

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3348965B2 (en) * 1994-03-31 2002-11-20 三井化学株式会社 Microporous biaxially stretched film comprising a composition of high molecular weight polyethylene and high molecular weight polypropylene, its production method and its use
JP3699561B2 (en) * 1997-04-23 2005-09-28 東燃化学株式会社 Polyolefin microporous membrane and method for producing the same

Also Published As

Publication number Publication date
JP4641706B2 (en) 2011-03-02
JPWO2002092677A1 (en) 2005-03-10
TW543224B (en) 2003-07-21
WO2002092677A1 (en) 2002-11-21
CN1509307A (en) 2004-06-30
KR100557380B1 (en) 2006-03-06
KR20030096395A (en) 2003-12-24

Similar Documents

Publication Publication Date Title
KR100648577B1 (en) Capillary Collapse Resistant Microporous Material and Method
EP0193318B1 (en) Microporous membrane of ultra-high molecular weight alpha-olefin polymer
CN1128835C (en) Polyolefin microporous film and method for preparing same
CN1255460C (en) Polyolefin microporous membrane
CN101796108B (en) Microporous polyolefin membrane, its production method, battery separator and battery
CN101184796B (en) Microporous polyethylene film having excellent physical properties productivity, and quality consistency, and method of producing same
CN101983219B (en) Polyolefin microporous membrane and products of winding
CN1134491C (en) Polyolefin microporous film and method for preparing same
TW200803015A (en) Polyolefins microporous film, spacer useful for battery and battery
TWI444296B (en) Polyolefins microporous film and the method thereof, spacer useful for battery, and battery
CN105393383B (en) Method of the manufacture for the diaphragm of electrochemical appliance and the diaphragm for electrochemical appliance by this method manufacture
EP3098256B1 (en) Polyolefin microporous membrane and method for producing same
KR101843806B1 (en) Polyolefin microporous membrane, separator for battery, and battery
EP3305838B1 (en) Method for preparing microporous membrane, microporous membrane, battery separator, and secondary battery
CN102218880A (en) Polyolefin microporous membrane
CN101448881A (en) Microporous polyolefin membrane, its production method, battery separator and battery
JPWO2013099607A1 (en) Polyolefin microporous membrane and method for producing the same
TW201840039A (en) Separator for lithium-ion secondary battery
CN103827185A (en) Microporous membrane
JP4606532B2 (en) Polyolefin microporous membrane
CN110382605A (en) Polyolefin micro porous polyolefin membrane and the battery for having used the polyolefin micro porous polyolefin membrane
WO2023071543A1 (en) Composite separator, electrochemical apparatus, and electronic device
JP2503007B2 (en) Microporous polypropylene film
JP4804630B2 (en) Microporous membrane and lithium battery separator
JPH0471416B2 (en)

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
ASS Succession or assignment of patent right

Owner name: ASAHI CHEMICAL CORP.

Free format text: FORMER OWNER: ASAHI KASEI CORPORATION

Effective date: 20060728

C41 Transfer of patent application or patent right or utility model
TR01 Transfer of patent right

Effective date of registration: 20060728

Address after: Tokyo, Japan

Patentee after: Asahi Kasei Chemical K. K.

Address before: Osaka

Patentee before: Asahi Kasei Kogyo K. K.

ASS Succession or assignment of patent right

Owner name: ASAHI KASEI ELECTRONICS MATERIALS CO., LTD.

Free format text: FORMER OWNER: ASAHI CHEMICAL CORP.

Effective date: 20091030

C41 Transfer of patent application or patent right or utility model
TR01 Transfer of patent right

Effective date of registration: 20091030

Address after: Tokyo, Japan

Patentee after: Asahi Chemical Corp.

Address before: Tokyo, Japan

Patentee before: Asahi Kasei Chemical K. K.

C41 Transfer of patent application or patent right or utility model
TR01 Transfer of patent right

Effective date of registration: 20160623

Address after: Tokyo, Japan

Patentee after: Asahi Kasei Kogyo K. K.

Address before: Tokyo, Japan

Patentee before: Asahi Chemical Corp.

CX01 Expiry of patent term
CX01 Expiry of patent term

Granted publication date: 20060510