JP2003217554A - Polyolefin micro porous membrane for battery separator - Google Patents
Polyolefin micro porous membrane for battery separatorInfo
- Publication number
- JP2003217554A JP2003217554A JP2002016006A JP2002016006A JP2003217554A JP 2003217554 A JP2003217554 A JP 2003217554A JP 2002016006 A JP2002016006 A JP 2002016006A JP 2002016006 A JP2002016006 A JP 2002016006A JP 2003217554 A JP2003217554 A JP 2003217554A
- Authority
- JP
- Japan
- Prior art keywords
- molecular weight
- polyethylene
- weight
- average molecular
- temperature
- 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.)
- Granted
Links
- 239000012982 microporous membrane Substances 0.000 title claims abstract description 16
- 229920000098 polyolefin Polymers 0.000 title claims abstract description 15
- 239000000203 mixture Substances 0.000 claims abstract description 40
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 claims abstract description 20
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 claims abstract description 18
- 239000004702 low-density polyethylene Substances 0.000 claims abstract description 12
- 229920001684 low density polyethylene Polymers 0.000 claims abstract description 11
- 230000008602 contraction Effects 0.000 abstract 1
- -1 polyethylene Polymers 0.000 description 29
- 239000004698 Polyethylene Substances 0.000 description 26
- 229920000573 polyethylene Polymers 0.000 description 26
- 239000012528 membrane Substances 0.000 description 16
- 230000000704 physical effect Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 9
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 7
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 6
- 239000005977 Ethylene Substances 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 229920001903 high density polyethylene Polymers 0.000 description 5
- 239000004700 high-density polyethylene Substances 0.000 description 5
- 239000011256 inorganic filler Substances 0.000 description 5
- 229910003475 inorganic filler Inorganic materials 0.000 description 5
- 230000035699 permeability Effects 0.000 description 5
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 4
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 4
- 238000004898 kneading Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229940057995 liquid paraffin Drugs 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004707 linear low-density polyethylene Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- YEVQZPWSVWZAOB-UHFFFAOYSA-N 2-(bromomethyl)-1-iodo-4-(trifluoromethyl)benzene Chemical compound FC(F)(F)C1=CC=C(I)C(CBr)=C1 YEVQZPWSVWZAOB-UHFFFAOYSA-N 0.000 description 1
- 241000255925 Diptera Species 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- 229910013075 LiBF Inorganic materials 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000009998 heat setting Methods 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229920000092 linear low density polyethylene Polymers 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012968 metallocene catalyst Substances 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 125000005498 phthalate group Chemical class 0.000 description 1
- 229920013716 polyethylene resin Polymers 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical class OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 125000003011 styrenyl group Chemical group [H]\C(*)=C(/[H])C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 description 1
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
-
- 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
-
- 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
- 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
-
- 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
-
- 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
- B01D2325/34—Molecular weight or degree of polymerisation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/34—Molecular weight or degree of polymerisation
- B01D2325/341—At least two polymers of same structure but different molecular weight
-
- 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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/494—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
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Cell Separators (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は電池セパレーター用
ポリオレフィン微多孔膜に関するものであり、特に電池
内での安全性向上に適した電池セパレーター用ポリオレ
フィン微多孔膜に関する。
【０００２】
【従来の発明】ポリオレフィン樹脂からなる多孔質膜
は、種々電池用セパレーターとして使用されている。な
かでも、ポリエチレン製微多孔膜は、膜の機械的強度や
耐薬品性、透過性に加えて、その融点が低く、電池内部
が加熱された時に、低い温度でセパレーターが溶融して
孔を閉塞することにより電流を遮断し、それ以上の温度
上昇を抑えるヒューズ効果を有している。従って、電池
の安全性の面から有用なものであるといえる。
【０００３】また、ヒューズ温度に達した後も、更に電
池内部の温度が上昇し、電流を遮断しているセパレータ
ーが溶融破断を起こして電池内でショートが起こること
がある。このような状況下においても確実に電流が遮断
できるような、高ショート温度もセパレーターに求めら
れている。一方、電池内部において高温状態になったと
きに、セパレーターの収縮により、ショートを起こして
しまうことがある。これに対しては、セパレーターの捲
回方向（以下、ＭＤという）に垂直な方向（以下、ＴＤ
という）の収縮応力が低いことが求められている。
【０００４】このように、電池内部が高温になったとき
に高い安全性を有する為には、低いヒューズ温度、高い
ショート温度、低いＴＤ熱収縮応力のセパレーターが必
要とされている。これまで、微多孔膜のヒューズ温度を
低くする試みとしては、特開平５−２５３０５号公報、
特開平９−２２０４５３号公報のように超高分子量ポリ
エチレンに低融点成分を加えた技術が開示されている。
【０００５】また、ショート温度を高くする試みとして
は、特開平６−９６７５３号公報などポリエチレン樹脂
にポリプロピレン樹脂をブレンドしたものが挙げられ
る。更に、ヒューズ温度を低く、且つショート温度を高
くするという試みとしては、特開平８−１３８６４３号
公報のように、超高分子量ポリオレフィンを含まないで
微多孔膜を作製する技術が開示されている。ＴＤ方向の
熱収縮応力を低くする技術としては、特開平１１−３２
２９８９号公報のように１軸延伸にて作製した膜が挙げ
られる。
【０００６】しかしながら、電池内部での急速な温度上
昇を考えたとき、これらの技術において評価されている
孔閉塞温度や破膜温度では、膜をオーブン中に入れた後
での抵抗値変化を測定したものや、遅い昇温速度での測
定などであり、電池内部での高圧力下での、急速な温度
上昇を再現できているとは言いがたく、更に熱収縮や膜
強度を含めた全ての安全性を満足させる特性をもつ膜は
得られていなかった。
【０００７】
【発明が解決しようとする課題】本発明は、低い孔閉塞
温度と高い破膜温度、そして低いＴＤ熱収縮応力と強い
破断強度を有する安全性に優れた、電池セパレーター用
ポリオレフィン微多孔膜を提供するものである。
【０００８】
【課題を解決するための手段】すなわち本発明は、系全
体の粘度平均分子量が１０万〜５０万であって、粘度平
均分子量５０万以上２００万未満の超高分子量ポリエチ
レンを５〜７０重量％、並びに低密度ポリエチレンを３
０〜９５重量％含有した組成物からなることを特徴とす
る電池セパレーター用ポリオレフィン微多孔膜である。
【０００９】
【発明の実施の形態】以下、本発明の好ましい態様を詳
細に説明する。本発明の電池セパレーター用微多孔膜は
系全体の粘度平均分子量が１０万〜５０万であり、好ま
しくは１０万〜４５万、更に好ましくは１０万〜４０万
である。粘度平均分子量が１０万未満であると、膜とし
て電池を作製する為の充分な強度が得られない。また、
粘度平均分子量が５０万以上であると、系の粘度が高
く、膜が溶融した際に孔の閉塞が遅くなり低いヒューズ
温度が得られない上、高温での収縮応力が大きくなって
しまう。
【００１０】本発明に用いるポリオレフィン組成物は、
粘度平均分子量５０万以上２００万未満の超高分子量ポ
リエチレンを５〜７０重量％、且つ低密度ポリエチレン
を３０〜９５重量％含有する。好ましくは前者を１０〜
６５重量％、後者を３５〜９０重量％、更に好ましくは
前者を２０〜６０重量％、後者を４０〜８０重量％含有
するものである。超高分子ポリエチレンの粘度平均分子
量は、５０万以上２００万未満、好ましくは５０万以上
１５０万未満、より好ましくは５０万以上１００万未
満、更に好ましくは５０万以上７０万未満である。超高
分子量ポリエチレンの分子量が５０万未満であると、延
伸にて高い強度が得られない。超高分子量ポリエチレン
の分子量が２００万を超えると、ポリエチレン混合物の
混錬性が悪く、成形性に劣る上に、膜全体の分子量が高
くなり、低いヒューズ温度が得られない。
【００１１】超高分子量ポリエチレンの含有量が５重量
％未満であると、ヒューズした後の溶融形状が保持され
にくいため、破膜を起こしてしまい、ショート温度が低
くなってしまう。更に、延伸において高い強度が得られ
ない。また、超高分子量ポリエチレンが７０重量％を超
えると膜全体の分子量が高くなることで、ヒューズ温度
が高くなってしまう。更に、収縮応力が大きくなること
で、溶融時の収縮が起こりやすくショート温度が低くな
ってしまう。
【００１２】一般的に、超高分子量ポリエチレンが含ま
れている効果を確認する為には、膜の伸張粘度を測定す
ると良い。超高分子量ポリエチレンが含まれている膜に
は、ひずみ硬化性が確認できる。本発明に用いる低密度
ポリエチレンとしては、高圧法により製造される分岐状
ポリエチレン（ＬＤＰＥ）や、低圧法による直鎖状の低
密度ポリエチレン（ＬＬＤＰＥ）が挙げられる。低密度
ポリエチレンの密度としては通常０．９１〜０．９３／
ｃｍ3が好ましい。低密度ポリエチレンの粘度平均分子
量は１〜４５万が好ましく、５〜４０万が更に好まし
い。
【００１３】本発明に用いる低密度ポリエチレンが３０
重量％未満であると、低融点成分が少ない為、ヒューズ
温度が高くなってしまい、高い安全性の膜が得られな
い。逆に９５重量％を超えると、高温での膜の形状保持
が難しく、破膜が起こりやすくなる為、高いショート温
度が得られない。また、本発明に用いるポリオレフィン
組成物に、系全体の粘度平均分子量が１０万〜５０万の
範囲内にある限り、粘度平均分子量が５０万未満の中密
度ポリエチレン、高密度ポリエチレン、メタロセン触媒
を用いて作製されたポリエチレン、更にはポリプロピレ
ンを加えることが出来る。
【００１４】本発明の電池セパレーター用微多孔膜のヒ
ューズ温度は１４２℃未満が好ましく、１４０℃未満が
より好ましく、１３８℃未満が更に好ましい。電池内部
の発熱を抑える為には、ヒューズ温度は１４２℃未満が
好ましい。本発明の微多孔膜のショート温度は１６０℃
以上が好ましく、１７０℃以上がより好ましく、１８０
℃以上が更に好ましい。電池内部での昇温速度を考えた
とき、１６０℃以上まで破膜せずに溶融状態を保ってい
ることが好ましい。
【００１５】本発明の微多孔膜のＴＤ方向の最大収縮応
力は６００ＫＰａ以下が好ましく、５００ＫＰａ以下が
より好ましく、４００ＫＰａ以下が更に好ましい。電池
内部で高温に曝された時のＴＤ方向の収縮を防ぐには、
ＴＤ最大収縮応力が６００ＫＰａ以下が好ましい。本発
明の微多孔膜のＭＤ引張破断強度は８０ＭＰａ以上であ
ることが好ましく、１００ＭＰａ以上であることが更に
好ましい。電池の捲回工程における引張り応力を考えた
時に、ＭＤ引張破断強度は８０ＭＰａ以上が好ましい。
【００１６】本発明の微多孔膜の透気度は１０００秒／
０．１ｄｍ3以下が好ましく、５００秒／０．１ｄｍ3以
下がより好ましく、２００秒／０．１ｄｍ3以下が更に
好ましい。高い放電容量を得る為にも、透気度は１００
０秒／０．１ｄｍ3以下が好ましい。本発明の微多孔膜
の膜厚は１〜５０μｍが好ましく、５〜３０μｍが更に
好ましい。本発明の微多孔膜の気孔率は２０％〜８０％
が好ましく、３０％〜７０％が更に好ましい。
【００１７】次に本発明のポリオレフィン微多孔膜の製
造例について説明する。この発明の膜は、例えば下記の
（ａ）〜（ｄ）の工程によって作られる。
（ａ）前記載の超高分子量ポリエチレンと低密度ポリエ
チレン、更に任意のポリオレフィンのブレンド物と有機
液状物、必要に応じて無機フィラー及び添加剤とともに
混合・造粒する工程。
（ｂ）（ａ）工程で得た混合物を、先端にＴ−ダイを装
着した押出機中で溶融混練し、Ｔ−ダイから押出しシー
ト状に成形する工程。
（ｃ）（ｂ）で得たシート状成型物より、有機液状物と
無機フィラーを抽出除去する工程。
（ｄ）（ｃ）の成型物を、１枚のまま、或いは数枚重ね
て、二軸に延伸処理する工程。
【００１８】本発明の製造工程をさらに詳しく説明す
る。工程（ａ）において混合オレフィン、有機液状体、
無機フィラーの合計重量に対する混合ポリオレフィンの
割合は１０〜６０重量％、有機液状体と無機フィラーの
割合の合計は４０〜９０重量％であることが好ましい。
膜の強度を保つためには、混合ポリオレフィンの割合が
１０重量％以上が好ましく、成形加工性時の流動性を保
つ為には、６０重量％未満が好ましい。有機液状体とし
てはフタル酸エステルやセバシン酸エステル等のエステ
ル類や流動パラフィン等が挙げられ、それらを単独で用
いても或いは混合物で用いてもよい。無機フィラーとし
ては、シリカ、マイカ、タルク等が挙げられ、それらを
単独で用いても或いは混合物で用いてもよい。
【００１９】尚、ポリオレフィン、有機液状物、無機フ
ィラーの他に、本発明を大きく阻害しない範囲で必要に
応じて酸化防止剤、紫外線吸収剤、滑剤、アンチブロッ
キング剤等の各種添加剤を添加することができる。工程
（ｄ）において二軸延伸する場合は、逐次二軸延伸でも
同時二軸延伸でもどちらでも構わない。さらに、延伸に
続いて、または後に、熱固定あるいは熱緩和等の熱処理
を行ってもかまわない。
【００２０】次に実施例によって本発明を更に詳細に説
明する。実施例において示される試験方法は次の通りで
ある。
（１）粘度平均分子量（Ｍｖ）
溶剤（デカリン）を用い、測定温度１３５℃における極
限粘度［η］を測定し、次式より算出した。
［η］＝６．２×１０(-4)×Ｍｖ0.7（Ｃｈｉａｎｇの
式）
（２）密度（ｇ／ｃｍ3）
ＡＳＴＭ Ｄ１２３８に準拠して測定した。
（３）膜厚（μｍ）
ダイヤルゲージ（尾崎製作所：ＰＥＡＣＯＣＫ Ｎｏ．
２５）にて測定した。
（４）気孔率（％）
２０ｃｍ角のサンプルをとり、その体積と質量から次式
を用いて計算した。
気孔率（％）＝（体積（ｃｍ3）−質量（ｇ）／ポリエ
チレンの密度）／体積（ｃｍ3）×１００
【００２１】（５）透気度（秒／０．１ｄｍ3）
ＪＩＳ Ｐ−８１１７準拠のガーレー式透気度計にて測
定した。
【００２２】（６）ヒューズ温度、ショート温度（℃）
厚さ１０μｍのニッケル箔を２枚（Ａ、Ｂ）用意し、一
方のニッケル箔Ａをスライドガラス上に、縦１０ｍｍ、
横１０ｍｍの正方形部分を残してテフロン（登録商標）
テープでマスキングすると共に固定する（図１参照）。
熱電対を繋いだセラミックスプレート上に、別のニッケ
ル箔Ｂを載せ、この上に規定の電解液で３時間浸漬させ
た、測定試料の微多孔膜を置き、その上からニッケル箔
を貼りつけたスライドガラスを載せ、更にシリコンゴム
を載せる。これをホットプレート上にセットした後、油
圧プレス機にて１．５ＭＰａの圧力をかけた状態で、１
５℃／ｍｉｎの速度で昇温した（図２参照）。この際の
インピーダンス変化を交流１Ｖ、１ｋＨｚの条件下で測
定した。この測定において、インピーダンスが１０００
Ωに達した時点の温度をヒューズ温度とし、孔閉塞状態
に達した後、再びインピーダンスが１０００Ωを下回っ
た時点の温度をショート温度とした。
【００２３】なお、規定の電解液の組成比は以下の通り
である。
溶媒の組成比（体積比）：炭酸プロピレン／炭酸エチレ
ン／δ−ブチルラクトン＝１／１／２
電解液の組成比：上記溶媒にてＬｉＢＦ4を１ｍｏｌ／
リットルの濃度になるように溶かし、０．５重量％にな
るようにトリオクチルフォスフェイトを加えた。
【００２４】（７）ＴＤ最大収縮応力（ＫＰａ）
熱機械的分析装置（セイコー電子工業社製ＴＭＡ１２
０）を用いて、以下の条件にて測定した。
サンプル形状：サンプル長（ＴＤ）×サンプル幅＝１０
ｍｍ×３ｍｍ
初期荷重：１．１８×１０-2（Ｎ）
昇温速度：１０℃／ｍｉｎ
収縮応力曲線において最大収縮荷重（Ｎ）を求め、下記
の式より最大収縮応力を算出した。
最大収縮応力（ＫＰａ）＝(最大収縮荷重／(３×Ｔ))×
１０6
Ｔ：サンプル厚み（μｍ）
【００２５】（８）引張破断強度（ＭＰａ）
引張試験機（島津オートグラフＡＧ−Ａ型）を用いて、
以下の条件にて測定した。
サンプル形状：サンプル長（ＴＤ）×サンプル幅＝１０
０ｍｍ×１０ｍｍ
チャック間距離：５０ｍｍ
引張速度：２００ｍｍ／ｍｉｎ
サンプル破断時の強度（Ｎ）を求め、下記の式により引
張破断強度（ＭＰａ）を算出した。
引張破断強度（ＭＰａ）＝（測定強度／Ｔ）×１０2
Ｔ：サンプル厚み（μｍ）
【００２６】
【実施例】［実施例１］ 粘度平均分子量５５万、密度
０．９５６ｇ／ｃｍ3の超高分子量ポリエチレン３０重
量％、粘度平均分子量３５万、密度０．９２９ｇ／ｃｍ
3の低密度ポリエチレン３０重量％、粘度平均分子量１
５万、密度０．９２５ｇ／ｃｍ3の線状低密度ポリエチ
レン４０重量％を混合したポリエチレンブレンドポリマ
ーを作製した。このポリエチレンブレンドポリマー４０
重量％に、フタル酸ジオクチル（ＤＯＰ）４１．２重量
％、微粉シリカ１８．８重量％を混合造粒した後、Ｔダ
イを装着した二軸押出機にて混練・押出し厚さ９０μｍ
のシート状に成形した。該成形物からＤＯＰと微粉シリ
カを抽出除去し微多孔膜とした。該微多孔膜を２枚重ね
て１１５℃に加熱のもと、縦方向に４．５倍延伸した
後、横方向に１．８倍延伸した。使用したポリエチレン
の混合組成を表１に、得られた膜の物性を表２に記載し
た。
【００２７】［実施例２］ 粘度平均分子量６５万、密
度０．９５６ｇ／ｃｍ3の超高分子量ポリエチレンを用
いた以外は、実施例１と同様にして作製した。使用した
ポリエチレンの混合組成を表１に、得られた膜の物性を
表２に記載した。
【００２８】［実施例３］ 粘度平均分子量９５万、密
度０．９５５ｇ／ｃｍ3の超高分子量ポリエチレンを用
いた以外は、実施例１と同様にして作製した。使用した
ポリエチレンの混合組成を表１に、得られた膜の物性を
表２に記載した。
【００２９】［実施例４］ 粘度平均分子量５５万、密
度０．９５６ｇ／ｃｍ3の超高分子量ポリエチレンを３
０重量％、粘度平均分子量１５万、密度０．９５４ｇ／
ｃｍ3の高密度ポリエチレンを３０重量％、粘度平均分
子量１５万、密度０．９２５ｇ／ｃｍ3の線状低密度ポ
リエチレン４０重量％をポリエチレン混合物として用い
た以外は、実施例１と同様にして作製した。使用したポ
リエチレンの混合組成を表１に、得られた膜の物性を表
２に記載した。
【００３０】［実施例５］ 粘度平均分子量９５万、密
度０．９５５ｇ／ｃｍ3の超高分子量ポリエチレンを２
０重量％、粘度平均分子量が３５万、密度０．９２９ｇ
／ｃｍ3の低密度ポリエチレン４０重量％、粘度平均分
子量１５万、密度０．９２５ｇ／ｃｍ3の鎖状低密度ポ
リエチレン４０重量％をポリエチレン混合物として用い
た以外は、実施例１と同様にして作製した。使用したポ
リエチレンの混合組成を表１に、得られた膜の物性を表
２に記載した。
【００３１】［実施例６］ 粘度平均分子量５５万、密
度０．９５６ｇ／ｃｍ3の超高分子量ポリエチレン６０
重量％、粘度平均分子量３５万、密度０．９２９ｇ／ｃ
ｍ 3の低密度ポリエチレン２０重量％、粘度平均分子量
１５万、密度０．９２５ｇ／ｃｍ3の線状低密度ポリエ
チレン２０重量％をポリエチレン混合物として用いた以
外は、実施例１と同様にして作製した。使用したポリエ
チレンの混合組成を表１に、得られた膜の物性を表２に
記載した。
【００３２】［実施例７］ 実施例１で得られたＤＯＰ
と微紛体シリカ抽出膜を、１１８℃に加熱のもと、縦方
向に５．５倍延伸した後、横方向に１．８倍延伸した以
外は、実施例１と同様に作製した。使用したポリエチレ
ンの混合組成を表１に、得られた膜の物性を表２に記載
した。
【００３３】［比較例１］ 粘度平均分子量２００万、
密度０．９３５ｇ／ｃｍ3の超高分子量ポリエチレンを
用いた以外は、実施例１と同様にして作製した。使用し
たポリエチレンの混合組成を表１に、得られた膜の物性
を表２に記載した。
【００３４】［比較例２］ 粘度平均分子量２００万、
密度０．９３５ｇ／ｃｍ3の超高分子量ポリエチレンを
用いた以外は、実施例４と同様にして作製した。使用し
たポリエチレンの混合組成を表１に、得られた膜の物性
を表２に記載した。
【００３５】［比較例３］ 粘度平均分子量４０万、密
度０．９５７ｇ／ｃｍ3の高密度ポリエチレンを５０重
量％、粘度平均分子量１５万、密度０．９２５ｇ／ｃｍ
3の線状低密度ポリエチレンを５０重量％をポリエチレ
ン混合物とした用いた以外は、実施例１と同様にして作
製した。使用したポリエチレンの混合組成を表１に、得
られた膜の物性を表２に記載した。
【００３６】［比較例４］ 粘度平均分子量３００万、
密度０．９４０ｇ／ｃｍ3の超高分子量ポリエチレンを
４０重量％、粘度平均分子量１５万、密度０．９２５ｇ
／ｃｍ3の線状低密度ポリエチレン６０重量％をポリエ
チレン混合物として実施例１と同様にして作製したが、
均一な膜が成形できず、縦延伸時に破断が多発した為、
薄膜化が出来なかった。使用したポリエチレンの混合組
成を表１に記載した。
【００３７】［比較例５］ 粘度平均分子量２００万、
密度０．９３５ｇ／ｃｍ3の超高分子量ポリエチレンを
２０重量％、粘度平均分子量２５万、密度０．９５７ｇ
／ｃｍ3の高密度ポリエチレン８０重量％をポリエチレ
ン混合物として用いた以外は、実施例１と同様にして作
製した。使用したポリエチレンの混合組成を表１に、得
られた膜の物性を表２に記載した。
【００３８】［比較例６］ 粘度平均分子量２５万、密
度０．９５７ｇ／ｃｍ3の高密度ポリエチレンを８５重
量％、粘度平均分子量３５万、密度０．９２９ｇ／ｃｍ
3の低密度ポリエチレン１５重量％をタンブラーブレン
ダーを用いてドライブレンドし、ポリエチレン混合物を
得た。得られたポリエチレン混合物を、フィーダーによ
り二軸押出し機フィード口へ供給した。また、流動パラ
フィン（３７．７８℃における動粘度７．５９×１０―
5ｍ2／ｓ）を、プランジャーポンプにより二軸押出し機
シリンダーへ注入した。
【００３９】溶融混練し押し出される全混合物中に占め
る流動パラフィン量比は５５重量％となるように、フィ
ーダー及びポンプを調整した。溶融混練条件は、設定温
度２００℃、スクリュー回転数２４０ｒｐｍ、吐出量１
２ｋｇ／ｈで行った。続いて、溶融混練物を、Ｔ−ダイ
を経て表面温度２５℃に制御された冷却ロール上に押出
しキャストすることにより、厚み１８００μｍのゲルシ
ートを得た。次に、同時二軸テンター延伸機に導き、二
軸延伸を行った。設定延伸条件は、ＭＤ倍率７．０倍、
ＴＤ倍率６．５倍、設定温度１２０℃である。
【００４０】次に、メチルエチルケトン槽に導き、メチ
ルエチルケトン中に充分に浸漬して流動パラフィンを抽
出除去し、その後メチルエチルケトンを乾燥除去した。
さらに、ＴＤテンター熱固定機に導き、熱固定を行っ
た。熱固定条件は、設定温度１３０℃、出口倍率１．５
倍である。使用したポリエチレンの混合組成を表１に、
得られた膜の物性を表２に記載した。
【００４１】
【表１】
【００４２】
【表２】
【００４３】
【発明の効果】本発明の電池セパレーター用ポリオレフ
ィン微多孔膜は、低い孔閉塞温度と高い破膜温度、そし
て低い熱収縮応力と引張破断強度を備えており、高い安
全性が求められる有機溶媒系電池セパレーターとして使
用されるのに適している。DETAILED DESCRIPTION OF THE INVENTION
[0001]
TECHNICAL FIELD The present invention relates to a battery separator.
The present invention relates to a microporous polyolefin membrane, and particularly to a battery.
Polyol for battery separator suitable for safety improvement inside
It relates to a fin microporous membrane.
[0002]
BACKGROUND OF THE INVENTION Porous membrane made of polyolefin resin
Are used as separators for various batteries. What
Nevertheless, polyethylene microporous membranes are
Low melting point in addition to chemical resistance and permeability
When heated, the separator melts at low temperature
The current is shut off by closing the hole and the temperature
It has a fuse effect to suppress the rise. Therefore, the battery
It can be said that it is useful from the viewpoint of safety.
[0003] Further, after the fuse temperature is reached, the power is further supplied.
Separator whose temperature inside the pond rises and interrupts the current
-Causes a melt rupture and short circuit in the battery
There is. Reliable interruption of current even in such situations
High short-circuit temperature required for separators
Have been. On the other hand, when the temperature inside the battery becomes high
When the separator shrinks, causing a short circuit
Sometimes. On the other hand, the separator winding
Direction (hereinafter, referred to as TD)
That)ofLow shrinkage stress is required.
As described above, when the temperature inside the battery becomes high,
In order to have high safety, low fuse temperature, high
Short temperature, low TDheatA separator with shrinkage stress is required.
It is important. Until now, the fuse temperature of microporous membrane
As an attempt to lower it, JP-A-5-25305,
Japanese Patent Application Laid-Open No. 9-220453 discloses an ultra-high molecular weight poly.
A technique in which a low melting point component is added to ethylene is disclosed.
[0005] Further, as an attempt to increase the short-circuit temperature,
Is a polyethylene resin as disclosed in JP-A-6-96853.
Blended with polypropylene resin
You. Furthermore, lower the fuse temperature and increase the short-circuit temperature.
Japanese Patent Application Laid-Open No. 8-138463 describes an attempt to make
As in the gazette, do not contain ultra-high molecular weight polyolefin
A technique for producing a microporous membrane has been disclosed. TD direction
As a technique for reducing the heat shrinkage stress, JP-A-11-32
A film prepared by uniaxial stretching as described in Japanese Patent No. 2989 is cited.
Can be
However, due to the rapid temperature inside the battery,
When considering the rise, it is evaluated in these technologies
At pore closure and rupture temperatures, the membrane is placed in an oven
Measurement of the resistance change at
And rapid temperature under high pressure inside the battery
It is hard to say that it can reproduce the rise, heat shrinkage and film
Membrane with properties that satisfy all safety including strength
Had not been obtained.
[0007]
SUMMARY OF THE INVENTION The present invention is directed to a low hole occlusion.
Temperature and high rupture temperature, and low TD heat shrinkage stress and strong
For battery separators with excellent strength and breaking strength
The present invention provides a microporous polyolefin membrane.
[0008]
That is, the present invention provides a system
The body has a viscosity average molecular weight of 100,000 to 500,000,
Ultra high molecular weight polyethylene having an average molecular weight of 500,000 or more and less than 2,000,000
5 to 70% by weight of ren and 3 of low density polyethylene
Characterized by comprising a composition containing 0 to 95% by weight.
A microporous polyolefin membrane for a battery separator.
[0009]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.
This will be described in detail. The microporous membrane for a battery separator of the present invention is
The viscosity average molecular weight of the whole system is 100,000 to 500,000,
100,000 to 450,000, more preferably 100,000 to 400,000
It is. If the viscosity average molecular weight is less than 100,000,
Therefore, sufficient strength for producing a battery cannot be obtained. Also,
When the viscosity average molecular weight is 500,000 or more, the viscosity of the system is high.
And the lower the fuse, the slower the clogging of the hole when the film melts.
In addition to the lack of temperature, the shrinkage stress at high temperatures increases
I will.
The polyolefin composition used in the present invention comprises:
Ultra high molecular weight polymer having a viscosity average molecular weight of 500,000 or more and less than 2,000,000
5-70% by weight of ethylene and low density polyethylene
From 30 to 95% by weight. Preferably the former is 10
65% by weight, the latter 35 to 90% by weight, more preferably
20-60% by weight of the former and 40-80% by weight of the latter
Is what you do. Viscosity average molecule of ultra high molecular weight polyethylene
The amount is 500,000 or more and less than 2,000,000, preferably 500,000 or more
Less than 1.5 million, more preferably 500,000 or more but not more than 1 million
It is more preferably 500,000 or more and less than 700,000. Super high
If the molecular weight of the molecular weight polyethylene is less than 500,000,
High strength cannot be obtained by elongation. Ultra high molecular weight polyethylene
When the molecular weight exceeds 2,000,000, the polyethylene mixture
Poor kneading properties, poor moldability, and high molecular weight of the entire film
And a low fuse temperature cannot be obtained.
The content of ultra high molecular weight polyethylene is 5% by weight
%, The molten shape after the fuse is maintained
It is difficult to break the film, and the short-circuit temperature is low.
It will get worse. Furthermore, high strength is obtained in stretching.
Absent. Also, ultra high molecular weight polyethylene exceeds 70% by weight.
The molecular weight of the entire film increases,
Will be higher. Furthermore, the shrinkage stress increases.
In this case, shrinkage during melting is likely to occur,
I will.
[0012] Generally, ultra-high molecular weight polyethylene is included
To confirm the effect, measure the elongational viscosity of the membrane.
Good to be. For membranes containing ultra-high molecular weight polyethylene
Indicates the strain hardening property. Low density used in the present invention
As polyethylene, the branched shape produced by the high pressure method
Polyethylene (LDPE) or linear low-pressure
Density polyethylene (LLDPE). Low density
The density of polyethylene is usually 0.91 to 0.93 /
cmThreeIs preferred. Viscosity average molecule of low density polyethylene
The amount is preferably 150,000 to 450,000, more preferably 50,000 to 400,000.
No.
The low-density polyethylene used in the present invention is 30
If the content is less than 10% by weight, the low melting point component is small, so the fuse
The temperature is too high to obtain a highly secure membrane
No. Conversely, if the content exceeds 95% by weight, the shape of the film is maintained at high temperatures.
High short temperature
I can't get a degree. Also, the polyolefin used in the present invention
The composition has a viscosity average molecular weight of 100,000 to 500,000
Medium density with a viscosity average molecular weight of less than 500,000 as long as it is within the range
Degree polyethylene, high density polyethylene, metallocene catalyst
Polyethylene, and polypropylene
Can be added.
The microporous membrane for a battery separator of the present invention is
The fuse temperature is preferably less than 142 ° C, and less than 140 ° C.
More preferably, the temperature is less than 138 ° C. Inside the battery
Fuse temperature should be less than 142 ° C
preferable. The short-circuit temperature of the microporous membrane of the present invention is 160 ° C.
Or more, more preferably 170 ° C. or more,
C. or higher is more preferable. Considering the temperature rise rate inside the battery
Sometimes, the molten state is maintained without breaking the film up to 160 ° C or more.
Preferably.
The maximum shrinkage response in the TD direction of the microporous membrane of the present invention
The force is preferably 600 KPa or less, and 500 KPa or less.
More preferably, it is more preferably 400 KPa or less. battery
To prevent shrinkage in the TD direction when exposed to high temperatures inside
The TD maximum shrinkage stress is preferably 600 KPa or less. Departure
The MD tensile rupture strength of the bright microporous membrane is 80 MPa or more.
Preferably, it is more than 100 MPa
preferable. Considering tensile stress in battery winding process
Sometimes, the MD tensile strength at break is preferably 80 MPa or more.
The air permeability of the microporous membrane of the present invention is 1000 seconds /
0.1dmThreeThe following is preferable, and 500 seconds / 0.1 dmThreeLess than
Lower is more preferable, 200 seconds / 0.1 dmThreeThe following is further
preferable. In order to obtain a high discharge capacity, the air permeability is 100
0 seconds / 0.1dmThreeThe following is preferred. The microporous membrane of the present invention
Is preferably 1 to 50 μm, more preferably 5 to 30 μm.
preferable. The porosity of the microporous membrane of the present invention is 20% to 80%
Is preferable, and 30% to 70% is more preferable.
Next, the production of the microporous polyolefin membrane of the present invention is described.
A fabrication example will be described. The membrane of the present invention is, for example,
It is made by the steps (a) to (d).
(A) The ultrahigh molecular weight polyethylene and the low density polyethylene described above.
Tylene and any polyolefin blend and organic
Liquid, optionally with inorganic fillers and additives
The process of mixing and granulating.
(B) The mixture obtained in step (a) is equipped with a T-die at the tip.
Melt-kneaded in the extruder, and extruded from the T-die.
Step of forming into a shape.
(C) From the sheet-like molded product obtained in (b), an organic liquid
A step of extracting and removing the inorganic filler.
(D) One or more molded products of (c)
And a biaxial stretching process.
The production process of the present invention will be described in more detail.
You. In the step (a), the mixed olefin, the organic liquid,
Of mixed polyolefin to total weight of inorganic filler
The ratio is 10 to 60% by weight, the organic liquid and the inorganic filler
The total of the proportions is preferably from 40 to 90% by weight.
To maintain the strength of the membrane, the proportion of the mixed polyolefin
It is preferably at least 10% by weight to maintain fluidity during moldability.
For this purpose, less than 60% by weight is preferred. As an organic liquid
Of phthalates and sebacates
And liquid paraffin, which can be used alone
Or may be used in a mixture. As an inorganic filler
Examples include silica, mica, and talc.
They may be used alone or in a mixture.
Incidentally, polyolefins, organic liquids, inorganic
Besides the filter
Antioxidants, UV absorbers, lubricants, anti-blocks
Various additives such as a king agent can be added. Process
In the case of biaxial stretching in (d), even in the case of sequential biaxial stretching,
Either simultaneous biaxial stretching or both may be used. In addition, for stretching
Subsequent or later, heat treatment such as heat fixing or thermal relaxation
You can go.
Now, the present invention will be described in further detail with reference to Examples.
I will tell. The test methods shown in the examples are as follows:
is there.
(1) Viscosity average molecular weight (Mv)
Use a solvent (decalin) and measure the temperature at 135 ° C.
The limiting viscosity [η] was measured and calculated by the following equation.
[Η] = 6.2 × 10(-Four)× Mv0.7(Chiang's
formula)
(2) Density (g / cmThree)
It measured according to ASTM D1238.
(3) Film thickness (μm)
Dial gauge (Ozaki Seisakusho: PEACK No.
25).
(4) Porosity (%)
Take a 20cm square sample and calculate the following equation from the volume and mass
Was calculated.
Porosity (%) = (Volume (cmThree) -Mass (g) / Polyer
Density of styrene / volume (cm)Three) × 100
(5) Air permeability (sec / 0.1 dm)Three)
Measured with Gurley-type air permeability meter based on JIS P-8117
Specified.
(6) Fuse temperature, short-circuit temperature (° C)
Prepare two sheets of nickel foil (A, B) with a thickness of 10 μm,
One nickel foil A on a slide glass, length 10 mm,
Teflon (registered trademark) leaving a 10 mm wide square part
Mask and secure with tape (see FIG. 1).
Place another nickel on a ceramic plate with a thermocouple
On top of it and immersed in the specified electrolyte for 3 hours.
Place the microporous membrane of the measurement sample, and place nickel foil on it.
Place the slide glass with
Put. After setting this on a hot plate,
In a state where a pressure of 1.5 MPa is applied by a pressure press machine, 1
The temperature was raised at a rate of 5 ° C./min (see FIG. 2). At this time
Measure the impedance change under the conditions of AC 1V and 1kHz.
Specified. In this measurement, the impedance was 1000
The temperature at which Ω is reached is used as the fuse temperature, and the hole is closed.
The impedance drops below 1000Ω again.
The temperature at the time when the temperature was reached was defined as the short-circuit temperature.
The composition ratio of the specified electrolyte is as follows.
It is.
Solvent composition ratio (volume ratio): propylene carbonate / ethylene carbonate
/ Δ-butyl lactone = 1/1/2
Composition ratio of electrolyte: LiBF in the above solventFour1 mol /
Dissolve to a concentration of 1
Trioctyl phosphate was added as before.
(7) TD maximum shrinkage stress (KPa)
Thermomechanical analyzer (TMA12 manufactured by Seiko Instruments Inc.)
0) was measured under the following conditions.
Sample shape: sample length (TD) x sample width = 10
mm × 3mm
Initial load: 1.18 × 10-2(N)
Heating rate: 10 ° C / min
Find the maximum shrinkage load (N) in the shrinkage stress curve,
The maximum shrinkage stress was calculated from the following equation.
Maximum shrinkage stress (KPa) = (Maximum shrinkage load / (3 × T)) ×
106
T: Sample thickness (μm)
(8) Tensile breaking strength (MPa)
Using a tensile tester (Shimadzu Autograph AG-A type)
It was measured under the following conditions.
Sample shape: sample length (TD) x sample width = 10
0mm × 10mm
Distance between chucks: 50mm
Pulling speed: 200mm / min
Determine the strength (N) at the time of sample breakage, and subtract
Tensile breaking strength (MPa) was calculated.
Tensile breaking strength (MPa) = (measured strength / T) × 10Two
T: Sample thickness (μm)
[0026]
[Example 1] [Viscosity average molecular weight: 550,000, density]
0.956g / cmThreeUltra high molecular weight polyethylene 30
%, Viscosity average molecular weight 350,000, density 0.929 g / cm
ThreeLow-density polyethylene 30% by weight, viscosity average molecular weight 1
50,000, density 0.925g / cmThreeLinear low density polyethylene
Polyethylene blend polymer mixed with 40% by weight of len
Was prepared. This polyethylene blend polymer 40
41.2% by weight of dioctyl phthalate (DOP)
% And 18.8% by weight of finely divided silica are mixed and granulated.
Kneading and extruding with a twin screw extruder equipped with a
Into a sheet. DOP and fine powder
Mosquito was extracted and removed to form a microporous membrane. Stack two microporous membranes
And stretched 4.5 times in the machine direction under heating at 115 ° C.
Thereafter, the film was stretched 1.8 times in the transverse direction. Polyethylene used
Is shown in Table 1 and the physical properties of the obtained film are shown in Table 2.
Was.
Example 2 Viscosity average molecular weight: 650,000, dense
Degree 0.956g / cmThreeUsing ultra high molecular weight polyethylene
Except for the fact that it was made, it was produced in the same manner as in Example 1. used
Table 1 shows the mixed composition of polyethylene and the physical properties of the obtained film.
It is described in Table 2.
Example 3 Viscosity average molecular weight 950,000, dense
Degree 0.955g / cmThreeUsing ultra high molecular weight polyethylene
Except for the fact that it was made, it was produced in the same manner as in Example 1. used
Table 1 shows the mixed composition of polyethylene and the physical properties of the obtained film.
It is described in Table 2.
Example 4 Viscosity average molecular weight: 550,000, dense
Degree 0.956g / cmThreeOf ultra high molecular weight polyethylene
0% by weight, viscosity average molecular weight 150,000, density 0.954 g /
cmThree30% by weight of high density polyethylene
Particle size 150,000, density 0.925g / cmThreeLinear low-density
40% by weight of ethylene as polyethylene mixture
Other than the above, it was produced in the same manner as in Example 1. Used port
Table 1 shows the mixture composition of ethylene and the physical properties of the obtained film.
No. 2.
Example 5 Viscosity average molecular weight 950,000, dense
Degree 0.955g / cmThreeOf ultra high molecular weight polyethylene
0% by weight, viscosity average molecular weight 350,000, density 0.929g
/ CmThree40% by weight of low density polyethylene, viscosity average
Particle size 150,000, density 0.925g / cmThreeChain low density
40% by weight of ethylene as polyethylene mixture
Other than the above, it was produced in the same manner as in Example 1. Used port
Table 1 shows the mixture composition of ethylene and the physical properties of the obtained film.
No. 2.
Example 6: Viscosity average molecular weight: 550,000, dense
Degree 0.956g / cmThreeUltra high molecular weight polyethylene 60
Weight%, viscosity average molecular weight 350,000, density 0.929g / c
m Three20% by weight of low density polyethylene, viscosity average molecular weight
150,000, density 0.925g / cmThreeLinear low density polye
20% by weight of styrene was used as a polyethylene mixture.
The other parts were manufactured in the same manner as in Example 1. Polyet used
Table 1 shows the mixture composition of styrene, and Table 2 shows the physical properties of the obtained film.
Described.
Example 7 DOP obtained in Example 1
And the fine silica powder extraction membrane, heated to 118 ° C,
After stretching 5.5 times in the transverse direction, and then stretching 1.8 times in the transverse direction.
The other parts were manufactured in the same manner as in Example 1. Polyethylene used
Table 1 shows the composition of the mixture, and Table 2 shows the physical properties of the resulting film.
did.
Comparative Example 1 A viscosity average molecular weight of 2,000,000,
Density 0.935g / cmThreeOf ultra high molecular weight polyethylene
Except having used, it produced similarly to Example 1. use
Table 1 shows the mixed composition of the obtained polyethylene, and the physical properties of the obtained film.
Are shown in Table 2.
Comparative Example 2 A viscosity average molecular weight of 2,000,000,
Density 0.935g / cmThreeOf ultra high molecular weight polyethylene
Except having used, it produced similarly to Example 4. use
Table 1 shows the mixed composition of the obtained polyethylene, and the physical properties of the obtained film.
Are shown in Table 2.
Comparative Example 3 A viscosity average molecular weight of 400,000, dense
Degree 0.957g / cmThree50 high-density polyethylene
%, Viscosity average molecular weight 150,000, density 0.925 g / cm
Three50% by weight of low-density linear polyethylene
The procedure was the same as in Example 1 except that
Made. Table 1 shows the mixed composition of the polyethylene used.
Table 2 shows the physical properties of the obtained film.
Comparative Example 4 A viscosity average molecular weight of 3,000,000,
Density 0.940g / cmThreeOf ultra high molecular weight polyethylene
40% by weight, viscosity average molecular weight 150,000, density 0.925g
/ CmThree60% by weight of linear low density polyethylene
It was made in the same manner as in Example 1 as a styrene mixture,
Because a uniform film could not be formed and breakage occurred frequently during longitudinal stretching,
The film could not be thinned. Mixed set of polyethylene used
The results are shown in Table 1.
Comparative Example 5 A viscosity average molecular weight of 2,000,000,
Density 0.935g / cmThreeOf ultra high molecular weight polyethylene
20% by weight, viscosity average molecular weight 250,000, density 0.957g
/ CmThree80% by weight of high-density polyethylene
Except that it was used as a mixture of
Made. Table 1 shows the mixed composition of the polyethylene used.
Table 2 shows the physical properties of the obtained film.
Comparative Example 6 A viscosity-average molecular weight of 250,000, dense
Degree 0.957g / cmThree85 layers of high density polyethylene
%, Viscosity average molecular weight 350,000, density 0.929 g / cm
Three15% by weight of low density polyethylene
Dry blend using a mixer
Obtained. The obtained polyethylene mixture is passed through a feeder.
The mixture was fed to a twin screw extruder feed port. In addition, liquid para
Fins (Kinematic viscosity at 37.78 ° C. 7.59 × 10 −
FivemTwo/ S) using a plunger pump
Injected into cylinder.
Accounts for the total mixture extruded by melt-kneading
The liquid paraffin content ratio should be 55% by weight.
The loader and pump were adjusted. Melt kneading conditions are set
Degree 200 ° C, screw rotation speed 240 rpm, discharge amount 1
The test was performed at 2 kg / h. Subsequently, the melt-kneaded material is placed on a T-die
Extrusion onto a cooling roll controlled to a surface temperature of 25 ° C
And cast it into a 1800 μm thick gel
I got it. Next, it is led to a simultaneous biaxial tenter stretching machine,
Axial stretching was performed. The setting stretching conditions are: MD magnification 7.0 times,
The TD magnification is 6.5 and the set temperature is 120 ° C.
Next, the mixture was led to a methyl ethyl ketone tank,
Liquid paraffin by fully immersing in
Then, methyl ethyl ketone was removed by drying.
Furthermore, it leads to a TD tenter heat fixing machine and performs heat fixing.
Was. The heat setting conditions were as follows: set temperature 130 ° C, outlet magnification 1.5
It is twice. Table 1 shows the mixed composition of the polyethylene used.
Table 2 shows the physical properties of the obtained film.
[0041]
[Table 1]
[0042]
[Table 2]
[0043]
The polyolefin for a battery separator of the present invention
Microporous membranes have low pore closure temperatures, high rupture temperatures, and
Low heat shrinkage stress and tensile rupture strength.
Used as an organic solvent-based battery separator that requires integrity
Suitable to be used.
【図面の簡単な説明】
【図１】ヒューズ温度、ショート温度を測定する際に使
用するニッケル箔付きスライドガラスを示す平面図。
【図２】ヒューズ温度、ショート温度測定装置の概略
図。
【図３】実施例１及び比較例１のインピーダンスの推移
を表すグラフ。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a slide glass with a nickel foil used for measuring a fuse temperature and a short-circuit temperature. FIG. 2 is a schematic diagram of a fuse temperature and short-circuit temperature measuring device. FIG. 3 is a graph showing a change in impedance of Example 1 and Comparative Example 1.
Claims (1)
万であって、粘度平均分子量５０万以上２００万未満の
超高分子量ポリエチレンを５〜７０重量％、並びに低密
度ポリエチレンを３０〜９５重量％含有した組成物から
なることを特徴とする電池セパレーター用ポリオレフィ
ン微多孔膜。Claims: 1. The viscosity average molecular weight of the whole system is 100,000 to 50.
For a battery separator, comprising a composition containing 5 to 70% by weight of ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 500,000 or more and less than 2,000,000 and 30 to 95% by weight of low density polyethylene. Polyolefin microporous membrane.
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|---|---|---|---|
| JP2002016006A JP4310424B2 (en) | 2002-01-24 | 2002-01-24 | Polyolefin microporous membrane for battery separator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002016006A JP4310424B2 (en) | 2002-01-24 | 2002-01-24 | Polyolefin microporous membrane for battery separator |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2003217554A true JP2003217554A (en) | 2003-07-31 |
| JP2003217554A5 JP2003217554A5 (en) | 2005-08-11 |
| JP4310424B2 JP4310424B2 (en) | 2009-08-12 |
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| WO2008093575A1 (en) * | 2007-01-30 | 2008-08-07 | Asahi Kasei E-Materials Corporation | Multilayer porous membrane and method for producing the same |
| US8283073B2 (en) | 2007-01-30 | 2012-10-09 | Asahi Kasei E-Materials Corporation | Microporous polyolefin membrane |
| KR101227325B1 (en) * | 2007-01-30 | 2013-03-27 | 아사히 가세이 이-매터리얼즈 가부시키가이샤 | Multilayer porous membrane and method for producing the same |
| US9293752B2 (en) | 2007-01-30 | 2016-03-22 | Asahi Kasei E-Materials Corporation | Multilayer porous membrane and production method thereof |
| EP2116372B1 (en) * | 2007-01-30 | 2018-03-28 | Asahi Kasei Kabushiki Kaisha | Multilayer porous membrane and production method thereof |
| WO2015009055A1 (en) * | 2013-07-17 | 2015-01-22 | 삼성에스디아이 주식회사 | Porous separator and manufacturing method therefor |
| KR20150009856A (en) * | 2013-07-17 | 2015-01-27 | 제일모직주식회사 | Porous polymeric separator and a method for preparing the same |
| KR101627738B1 (en) | 2013-07-17 | 2016-06-07 | 제일모직 주식회사 | Porous polymeric separator and a method for preparing the same |
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