JP2000248093A - Microporous polyolefin membrane and its production - Google Patents
Microporous polyolefin membrane and its productionInfo
- Publication number
- JP2000248093A JP2000248093A JP11055461A JP5546199A JP2000248093A JP 2000248093 A JP2000248093 A JP 2000248093A JP 11055461 A JP11055461 A JP 11055461A JP 5546199 A JP5546199 A JP 5546199A JP 2000248093 A JP2000248093 A JP 2000248093A
- Authority
- JP
- Japan
- Prior art keywords
- polyolefin
- molecular weight
- microporous
- membrane
- weight
- 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
- 229920000098 polyolefin Polymers 0.000 title claims abstract description 141
- 239000012528 membrane Substances 0.000 title claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000000203 mixture Substances 0.000 claims abstract description 53
- 239000002904 solvent Substances 0.000 claims description 33
- 238000009998 heat setting Methods 0.000 claims description 6
- 230000020169 heat generation Effects 0.000 abstract description 3
- 230000001747 exhibiting effect Effects 0.000 abstract description 2
- 239000011800 void material Substances 0.000 abstract 1
- -1 polyethylene Polymers 0.000 description 37
- 239000004698 Polyethylene Substances 0.000 description 33
- 229920000573 polyethylene Polymers 0.000 description 33
- 239000012982 microporous membrane Substances 0.000 description 26
- 238000000034 method Methods 0.000 description 22
- 229920001903 high density polyethylene Polymers 0.000 description 10
- 239000004700 high-density polyethylene Substances 0.000 description 10
- 238000002844 melting Methods 0.000 description 10
- 230000008018 melting Effects 0.000 description 10
- 229920000642 polymer Polymers 0.000 description 10
- 230000035699 permeability Effects 0.000 description 9
- 238000001816 cooling Methods 0.000 description 8
- 230000000704 physical effect Effects 0.000 description 8
- 239000000047 product Substances 0.000 description 7
- 229920000089 Cyclic olefin copolymer Polymers 0.000 description 6
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 6
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 6
- 229920001577 copolymer Polymers 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 229920000092 linear low density polyethylene Polymers 0.000 description 6
- 239000004707 linear low-density polyethylene Substances 0.000 description 6
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 6
- 239000004711 α-olefin Substances 0.000 description 6
- 229920001684 low density polyethylene Polymers 0.000 description 5
- 239000004702 low-density polyethylene Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 229940057995 liquid paraffin Drugs 0.000 description 4
- 239000012968 metallocene catalyst Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 2
- 230000003078 antioxidant effect Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- SNRUBQQJIBEYMU-UHFFFAOYSA-N dodecane Chemical compound CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 230000010220 ion permeability Effects 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920013716 polyethylene resin Polymers 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- RSJKGSCJYJTIGS-UHFFFAOYSA-N undecane Chemical compound CCCCCCCCCCC RSJKGSCJYJTIGS-UHFFFAOYSA-N 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 1
- XKGKLYUXFRFGKU-UHFFFAOYSA-N CC.F.F.F Chemical compound CC.F.F.F XKGKLYUXFRFGKU-UHFFFAOYSA-N 0.000 description 1
- 101000974007 Homo sapiens Nucleosome assembly protein 1-like 3 Proteins 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 102100022398 Nucleosome assembly protein 1-like 3 Human genes 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 229920010741 Ultra High Molecular Weight Polyethylene (UHMWPE) Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 125000000753 cycloalkyl group Chemical group 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 229910003475 inorganic filler Inorganic materials 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- BKIMMITUMNQMOS-UHFFFAOYSA-N nonane Chemical compound CCCCCCCCC BKIMMITUMNQMOS-UHFFFAOYSA-N 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 238000011076 safety test Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000001993 wax Substances 0.000 description 1
Classifications
-
- 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
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Cell Separators (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、超高分子量ポリオ
レフィンからなる微多孔膜に関し、特に電池セパレータ
用ポリオレフィン微多孔膜に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microporous membrane made of an ultrahigh molecular weight polyolefin, and more particularly to a microporous polyolefin membrane for a battery separator.
【０００２】[0002]
【従来の技術】ポリオレフィン微多孔膜は、有機溶媒に
不溶であり、かつ電解質や電極活物質に対して安定であ
るため、電池のセパレータ、特にリチウムイオン１次・
２次電池のセパレータ、電気自動車等の大型電池用セパ
レータ、コンデンサーのセパレータ、各種の分離膜、水
処理膜、限外濾過膜、精密濾過膜、逆浸透濾過膜、各種
フィルター、透湿防水衣料またははその基材として広く
用いられている。従来から、ポリオレフィン微多孔膜
は、ポリオレフィンに有機媒体及び微粉末シリカ等の無
機粉体を混合し溶融成形後、有機媒体及び無機粉体を抽
出して微多孔膜を得る方法は知られているが、無機物の
抽出する工程が必要であり、得られた膜の透過性は無機
粉体の粒径によるところが大きく、その制御は難しかっ
た。2. Description of the Related Art Microporous polyolefin membranes are insoluble in organic solvents and stable against electrolytes and electrode active materials.
Separators for secondary batteries, separators for large batteries such as electric vehicles, separators for capacitors, various separation membranes, water treatment membranes, ultrafiltration membranes, microfiltration membranes, reverse osmosis filtration membranes, various filters, moisture-permeable waterproof clothing or Is widely used as the base material. Conventionally, a method for obtaining a microporous film by mixing a polyolefin with an organic medium and an inorganic powder such as finely divided silica, melt-molding the polyolefin, and extracting the organic medium and the inorganic powder has been known. However, a step of extracting an inorganic substance was required, and the permeability of the obtained membrane largely depended on the particle size of the inorganic powder, and it was difficult to control the permeability.
【０００３】また、超高分子量ポリオレフィンを用いた
高強度の微多孔膜の製造法が種々提案されている。例え
ば、特開昭６０−２４２０３５号公報、特開昭６１−１
９５１３２号公報、特開昭６１−１９５１３３号公報、
特開昭６３−３９６０２号公報、特開昭６３−２７３６
５１号公報、特開平３−６４３３４号公報、特開平３−
１０５８５１号公報等には、超高分子量ポリオレフィン
を含むポリオレフィン組成物を溶媒に加熱溶解した溶液
からゲル状シートを成形し、前記ゲル状シートを加熱延
伸、溶媒の抽出除去による微多孔膜を製造する方法が記
載されているが、これらの技術によるポリオレフィン微
多孔膜は、孔径分布が狭くかつ孔径が小さいことが特徴
で、電池用セパレータ等に用いられている。[0003] Also, various methods for producing a high-strength microporous membrane using an ultrahigh molecular weight polyolefin have been proposed. For example, JP-A-60-242035 and JP-A-61-1
No. 95132, JP-A-61-195133,
JP-A-63-39602, JP-A-63-2736
No. 51, JP-A-3-64334, JP-A-3-64334
Japanese Patent No. 105851 discloses a method for producing a microporous film by forming a gel-like sheet from a solution obtained by heating and dissolving a polyolefin composition containing an ultra-high-molecular-weight polyolefin in a solvent, heating and stretching the gel-like sheet and extracting and removing the solvent. Although a method is described, the microporous polyolefin membrane by these techniques is characterized by a narrow pore size distribution and a small pore size, and is used for a battery separator and the like.
【０００４】最近のリチウムイオン電池は、電池特性、
電池安全性、電池生産性を向上させることが要求されて
いる。特に電池の安全性を向上させるためには、セパレ
ータのシャットダウン特性を改良することが非常に有効
である。シャットダウン特性とは、電池短絡時の発熱に
よってセパレータの孔が閉塞してイオン透過性を消失さ
せて、それ以上の発熱を抑えることであるが、従来は、
特開平５−２５３０５号公報や特開平９−２５９８５８
号公報等に示されているように、シャットダウン開始温
度を低下させたセパレータが検討されていた。しかしな
がら、実際の電池安全性試験によって、電池内部の昇温
は非常に短時間で起こっており、非常に短時間でセパレ
ータのシャットダウンが起こるかどうかが重要であるこ
とがわかってきた。そこで、電池短絡時の急速な温度上
昇条件下ですばやく目詰まりするセパレータの開発が望
まれるようになってきている。[0004] Recent lithium ion batteries have battery characteristics,
It is required to improve battery safety and battery productivity. In particular, in order to improve the safety of the battery, it is very effective to improve the shutdown characteristics of the separator. The shutdown characteristic is to suppress the further heat generation by closing the pores of the separator due to heat generation at the time of battery short circuit and losing ion permeability, but conventionally,
JP-A-5-25305 and JP-A-9-259858
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. HEI 9-205, a separator with a reduced shutdown start temperature has been studied. However, an actual battery safety test has shown that the temperature rise inside the battery occurs in a very short time, and it is important to determine whether the shutdown of the separator occurs in a very short time. Therefore, it has been desired to develop a separator that quickly becomes clogged under the condition of a rapid temperature increase at the time of battery short circuit.
【０００５】[0005]
【発明が解決しようとする課題】本発明の目的は、高収
縮率、高強度で、発熱した場合に高速シャットダウン機
能を有し、収縮率と突刺強度のバランスがとれ、電池用
セパレータとして用いた場合に電池特性に優れた安全性
の高いポリオレフィン微多孔膜を提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery separator having a high shrinkage ratio, a high strength, a high-speed shutdown function when heat is generated, a balance between shrinkage ratio and piercing strength. An object of the present invention is to provide a highly safe polyolefin microporous membrane excellent in battery characteristics in such a case.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、上記課題
を解決するために鋭意研究の結果、超高分子量ポリオレ
フィンまたはそれを含有するポリオレフィン組成物を用
い、溶剤との特定濃度の溶液から得たゲル状成形物を、
延伸条件、熱セット条件等を最適化することにより、
高速シャットダウン機能を有するポリオレフィン微多孔
膜が得られることを見出し、本発明に想到した。Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, using ultra-high molecular weight polyolefin or a polyolefin composition containing the same, from a solution having a specific concentration with a solvent. The obtained gel-like molded product is
By optimizing stretching conditions, heat setting conditions, etc.,
The present inventors have found that a microporous polyolefin membrane having a high-speed shutdown function can be obtained, and have reached the present invention.
【０００７】すなわち、本発明は、重量平均分子量が５
０万以上の超高分子量ポリオレフィン（Ａ）又は重量平
均分子量５０万以上の超高分子量ポリオレフィンを含む
組成物（Ｂ）からなるポリオレフィン微多孔膜であっ
て、空孔率が３５〜９５％、熱収縮率が３％を超えて１
５％以下、突刺強度が４００〜６５０ｇ／２５μｍであ
ることを特徴とするポリオレフィン微多孔膜である。That is, according to the present invention, the weight average molecular weight is 5
A polyolefin microporous membrane comprising an ultrahigh molecular weight polyolefin (A) having a molecular weight of at least 100,000 or a composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of at least 500,000, having a porosity of 35 to 95%, Shrinkage rate exceeding 3% 1
It is a polyolefin microporous membrane characterized by having a puncture strength of not more than 5% and a puncture strength of 400 to 650 g / 25 μm.
【０００８】また、本発明は、重量平均分子量５０万以
上の超高分子量ポリオレフィン（Ａ）又は重量平均分子
量５０万以上の超高分子量ポリオレフィンを含む組成物
（Ｂ）５〜２５重量％、溶剤９５〜７５重量％からなる
溶液を、溶融押出しによりゲル状物を得、当該ゲル状物
を３×３倍以上に延伸し、しかる後に溶剤を除去、乾燥
後、９５℃以上１２１℃以下にて熱セットを行うことを
特徴とする上記のポリオレフィン微多孔膜の製造方法で
ある。Further, the present invention relates to an ultrahigh molecular weight polyolefin (A) having a weight average molecular weight of 500,000 or more or a composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more, a solvent 95%. A solution consisting of ７５75% by weight is melt-extruded to obtain a gel, and the gel is stretched 3 × 3 times or more, then the solvent is removed, dried, and heated at 95 ° C. to 121 ° C. The method for producing a microporous polyolefin membrane described above, wherein the setting is performed.
【０００９】本発明の好ましい態様を以下に示す。 （１）重量平均分子量５０万以上の超高分子量ポリオレ
フィンが、ポリエチレンまたはポリプロピレンからなる
前記ポリオレフィン微多孔膜。 （２）平均貫通孔径が０．０１〜０．０５μｍであるこ
とを特徴とする請求項１、（１）記載のポリオレフィン
微多孔膜。 （３）重量平均分子量５０万以上の超高分子量ポリオレ
フィンを含む組成物（Ｂ）が、重量平均分子量１００万
以上の超高分子量ポリオレフィン（Ｂ−１）と、重量平
均分子量１０万以上１００万未満の高密度ポリエチレン
（Ｂ−２）とからなる前記ポリオレフィン微多孔膜。 （４）重量平均分子量５０万以上の超高分子量ポリオレ
フィンを含む組成物（Ｂ）が、重量平均分子量１００万
以上の超高分子量ポリオレフィン（Ｂ−１）と、重量平
均分子量１０万以上１００万未満の高密度ポリエチレン
（Ｂ−２）、及びポリエチレン系シャットダウンポリマ
ー（Ｂ−３）とからなり、（Ｂ−１）と（Ｂ−２）との
合計の重量と、（Ｂ−３）との重量の比が７０〜９５／
５〜３０であり、かつ（Ｂ−３）が低密度ポリエチレン
（ＬＤＰＥ）、線状低密度ポリエチレン（ＬＬＤＰ
Ｅ）、分子量１０００〜４０００の低分子量ポリエチレ
ン及びメタロセン触媒により得られたポリエチレン系重
合体よりなる群より少なくとも一つ選ばれたポリマーか
らなることを特徴とする前記ポリオレフィン微多孔膜。 （５）融点におけるシャットダウン時間が、１０秒以下
であることを特徴とする前記ポリオレフィン微多孔膜。 （６）熱収縮率がＭＤ、ＴＤともに５％〜１５％である
ことを特徴とする前記ポリオレフィン微多孔膜。 （７）前記ポリオレフィン微多孔膜をセパレータとして
用いた電池において、電極と前記セパレータとを８０
℃、１０ｋｇ／ｃｍ２でプレスした時の剥離強度が、１
ｇ以上であることを特徴とする前記電池。Preferred embodiments of the present invention are described below. (1) The microporous polyolefin membrane described above, wherein the ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more is made of polyethylene or polypropylene. (2) The microporous polyolefin membrane according to (1), wherein the average through hole diameter is 0.01 to 0.05 μm. (3) The composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more is composed of an ultrahigh molecular weight polyolefin (B-1) having a weight average molecular weight of 1,000,000 or more and a weight average molecular weight of 100,000 or more and less than 1,000,000. The microporous polyolefin membrane comprising high-density polyethylene (B-2). (4) The composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more is composed of an ultrahigh molecular weight polyolefin (B-1) having a weight average molecular weight of 1,000,000 or more and a weight average molecular weight of 100,000 or more and less than 1,000,000. Of high-density polyethylene (B-2) and polyethylene-based shutdown polymer (B-3), and the total weight of (B-1) and (B-2) and the weight of (B-3) Is 70-95 /
5 to 30, and (B-3) is low density polyethylene (LDPE), linear low density polyethylene (LLDP)
E), said microporous polyolefin membrane comprising a polymer selected from at least one selected from the group consisting of low molecular weight polyethylene having a molecular weight of 1,000 to 4,000 and a polyethylene polymer obtained by a metallocene catalyst. (5) The polyolefin microporous membrane, wherein the shutdown time at the melting point is 10 seconds or less. (6) The microporous polyolefin membrane, wherein the heat shrinkage is 5% to 15% for both MD and TD. (7) In a battery using the polyolefin microporous membrane as a separator, an electrode and the separator are
At a pressure of 10 kg / cm 2 at a peel strength of 1
g or more.
【００１０】[0010]
【発明の実施の形態】本発明のポリオレフィン微多孔膜
を、構成成分、物性、製法について、以下に詳細に説明
する。 １．ポリオレフィン 本発明のポリオレフィン微多孔膜で用いる超高分子量ポ
リオレフィン（Ａ）は、重量平均分子量５０万以上の超
高分子量ポリオレフィンであり、好ましくは重量平均分
子量１００万〜１５００万の超高分子量ポリオレフィン
である。ポリオレフィン（Ａ）の重量平均分子量が５０
万未満では、膜強度の低下がおこるので好ましくない。BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin microporous membrane of the present invention will be described in detail below with respect to constituent components, physical properties, and a production method. 1. Polyolefin The ultrahigh molecular weight polyolefin (A) used in the microporous polyolefin membrane of the present invention is an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more, preferably an ultrahigh molecular weight polyolefin having a weight average molecular weight of 1,000,000 to 15,000,000. . The weight average molecular weight of the polyolefin (A) is 50
If it is less than 10,000, the strength of the film is undesirably reduced.
【００１１】また、重量平均分子量５０万以上の超高分
子量ポリオレフィンを含む組成物（Ｂ）としては、特に
制限はないが、例えば、重量平均分子量１００万以上、
好ましくは重量平均分子量が１５０万以上、より好まし
くは重量平均分子量１５０万〜１５００万の超高分子量
ポリオレフィン（Ｂ−１）と、重量平均分子量１万以上
１００万未満、好ましくは重量平均分子量１０万以上５
０万未満のポリオレフィン（Ｂ−２）とからなるポリオ
レフィン組成物（Ｂ）である。重量平均分子量１００万
以上の超高分子量ポリオレフィン（Ｂ−１）成分が、１
重量％以上含有されている必要がある。超高分子量ポリ
オレフィン（Ｂ−１）の含有率が１重量％未満では、超
高分子量ポリオレフィンの分子鎖の絡み合いがほとんど
形成されず、高強度の微多孔膜を得ることができない。
ポリオレフィン（Ｂ−２）の重量平均分子量が１０万未
満であると、得られる微多孔膜の破断が起こりやすく、
目的の微多孔膜が得られない。The composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more is not particularly limited.
An ultrahigh molecular weight polyolefin (B-1) having a weight average molecular weight of 1.5 million or more, more preferably 1.5 million to 15 million, and a weight average molecular weight of 10,000 to less than 1,000,000, preferably 100,000 More than 5
A polyolefin composition (B) comprising less than 10,000 polyolefin (B-2). An ultrahigh molecular weight polyolefin (B-1) component having a weight average molecular weight of 1,000,000 or more
It must be contained in an amount of at least% by weight. When the content of the ultrahigh molecular weight polyolefin (B-1) is less than 1% by weight, entanglement of the molecular chain of the ultrahigh molecular weight polyolefin is hardly formed, and a high-strength microporous film cannot be obtained.
When the weight average molecular weight of the polyolefin (B-2) is less than 100,000, the resulting microporous membrane is likely to break,
The desired microporous membrane cannot be obtained.
【００１２】このようなポリオレフィンとしては、エチ
レン、プロピレン、１−ブテン、４−メチル−ペンテン
−１、１−ヘキセンなどを重合した結晶性の単独重合
体、２段重合体、又は共重合体及びこれらのブレンド物
等が挙げられる。これらのうちではポリプロピレン、ポ
リエチレン及びこれらの組成物等が好ましく、特に、重
量平均分子量１００万以上の超高分子量ポリエチレン
（Ｂ−１）と、重量平均分子量１０万以上１００万未満
の高密度ポリエチレン（Ｂ−２）とからなる組成物が好
ましい。Examples of the polyolefin include a crystalline homopolymer, a two-stage polymer or a copolymer obtained by polymerizing ethylene, propylene, 1-butene, 4-methyl-pentene-1, 1-hexene and the like. These blends are exemplified. Among these, polypropylene, polyethylene and their compositions are preferred. Particularly, ultrahigh molecular weight polyethylene (B-1) having a weight average molecular weight of 1,000,000 or more and high density polyethylene having a weight average molecular weight of 100,000 or more and less than 1,000,000 ( The composition consisting of B-2) is preferred.
【００１３】なお、上記ポリオレフィン又はポリオレフ
ィン組成物の分子量分布（重量平均分子量／数平均分子
量）は３００以下が好ましく、特に５〜５０であるのが
好ましい。分子量分布が３００を超えると、低分子量成
分による破断が起こり膜全体の強度が低下するため好ま
しくない。ポリオレフィン組成物を用いる場合は、重量
平均分子量が１００万以上の超高分子量ポリオレフィン
と、重量平均分子量が１０万以上１００万未満のポリオ
レフィンとを分子量分布が上記範囲となるように、適量
混合することによって得ることができ、このポリオレフ
ィン組成物は、上記分子量及び分子量分布を有していれ
ば、多段重合によるものであっても、２種以上のポリオ
レフィンによる組成物であっても、いずれでもよい。The molecular weight distribution (weight average molecular weight / number average molecular weight) of the polyolefin or polyolefin composition is preferably 300 or less, more preferably 5 to 50. If the molecular weight distribution exceeds 300, breakage due to low molecular weight components occurs, and the strength of the entire film is reduced, which is not preferable. When a polyolefin composition is used, an appropriate amount of an ultrahigh molecular weight polyolefin having a weight average molecular weight of 1,000,000 or more and a polyolefin having a weight average molecular weight of 100,000 or more and less than 1,000,000 are mixed so that the molecular weight distribution falls within the above range. The polyolefin composition may be one obtained by multi-stage polymerization or a composition comprising two or more polyolefins, as long as it has the above-mentioned molecular weight and molecular weight distribution.
【００１４】また、本発明で用いるポリオレフィン又は
ポリオレフィン組成物には、ポリオレフィン微多孔膜を
リチウム電池等のセパレーターとして用いた場合に低温
でのシャットダウン機能を付与できるポリマー（Ｂ−
３）を配合することができる。シャットダウン機能を付
与できるポリマーとしては、低密度ポリエチレン、低分
子量ポリエチレン、メタロセン触媒により得られるポリ
エチレン系共重合体等が挙げられる。Further, the polyolefin or polyolefin composition used in the present invention may comprise a polymer (B-B) capable of imparting a low-temperature shutdown function when a polyolefin microporous membrane is used as a separator for a lithium battery or the like.
3) can be blended. Examples of the polymer that can impart the shutdown function include low-density polyethylene, low-molecular-weight polyethylene, and a polyethylene-based copolymer obtained by using a metallocene catalyst.
【００１５】本発明において使用され得る低密度ポリエ
チレンとしては、高圧法による分岐状ポリエチレン（Ｌ
ＤＰＥ）及び低圧法による直鎖状の低密度ポリエチレン
（ＬＬＤＰＥ）である。ＬＤＰＥの場合、その密度は、
通常０．９１〜０．９３ｇ／ｃｍ３程度であり、またそ
のメルトインデックス（ＭＩ、１９０℃、２．１６ｋｇ
荷重）は、０．１〜２０ｇ／１０分であり、好ましく
は、０．５〜１０ｇ／１０分である。ＬＬＤＰＥの場
合、その密度は、通常０．９１〜０．９３ｇ／ｃｍ ３程
度であり、またそのメルトインデックス（ＭＩ、１９０
℃、２．１６ｋｇ荷重）は、０．１〜２５ｇ／１０分で
あり、好ましくは、０．５〜１０ｇ／１０分である。低
密度ポリエチレンの配合割合は、重量平均分子量が５０
万以上の超高分子量ポリオレフィンまたは組成物の５〜
３０重量％であるのが好ましい。[0015] Low density polyether which can be used in the present invention
As the styrene, a branched polyethylene (L
Linear low density polyethylene by DPE) and low pressure method
(LLDPE). In the case of LDPE, its density is
Usually 0.91 to 0.93 g / cm3It is about
Melt index (MI, 190 ° C, 2.16 kg)
Load) is 0.1 to 20 g / 10 min, and is preferably
Is 0.5 to 10 g / 10 minutes. Place of LLDPE
In this case, the density is usually 0.91 to 0.93 g / cm 3About
And its melt index (MI, 190
° C, 2.16 kg load) is 0.1 to 25 g / 10 min.
And preferably 0.5 to 10 g / 10 min. Low
The mixing ratio of the density polyethylene is such that the weight average molecular weight is 50.
Of more than 10,000 ultra-high molecular weight polyolefins or compositions
Preferably it is 30% by weight.
【００１６】本発明において使用され得る低分子量ポリ
エチレンとしては、分子量が１０００〜４０００、融点
が８０〜１３０℃のエチレン低重合体であり、密度が
０．９２〜０．９７ｇ／ｃｍ３のポリエチレンワックス
が好ましい。低分子量ポリエチレンの配合割合は、重量
平均分子量が５０万以上の超高分子量ポリオレフィン又
はポリオレフィン組成物（Ｂ）の５〜３０重量％である
のが好ましい。The low molecular weight polyethylene which can be used in the present invention is an ethylene low polymer having a molecular weight of 1,000 to 4,000, a melting point of 80 to 130 ° C. and a density of 0.92 to 0.97 g / cm 3 . Is preferred. The compounding ratio of the low molecular weight polyethylene is preferably 5 to 30% by weight of the ultrahigh molecular weight polyolefin or polyolefin composition (B) having a weight average molecular weight of 500,000 or more.
【００１７】また、本発明において使用され得る低温で
のシャットダウン機能を付与できるメタロセン触媒によ
り得られるポリエチレン系共重合体としては、メタロセ
ン触媒のようなシングルサイト触媒を用いて重合された
直鎖状エチレン−α−オレフィン共重合体、例えば、エ
チレン−ブテン−１共重合体、エチレン−ヘキセン−１
共重合体、エチレン−オクテン−１共重合体等を挙げる
ことができる。該エチレン−α−オレフィン共重合体の
融点（ＤＳＣピーク温度）は、９５〜１２５℃、好まし
くは１００℃〜１２０℃である。９５℃未満では高温条
件での電池特性を著しく悪化させてしまい、１２５℃を
超えると好ましい温度でシャットダウン機能を発揮しな
くなるため、好ましくない。該エチレン・α−オレフィ
ン共重合体の重量平均分子量Ｍｗと数平均分子量Ｍｎの
比Ｍｗ／Ｍｎ（Ｑ値）は、１．５〜３．０、好ましくは
１．５〜２．５であることが望ましい。このエチレン−
α−オレフィン共重合体をポリエチレンまたはそのポリ
エチレン組成物に加えることにより、ポリエチレン微多
孔膜をリチウム電池等のセパレーターとして用い、電極
が短絡して電池内部の温度が上昇した時、低温でシャッ
トダウンする機能を付与される。さらに、シャットダウ
ン時の膜抵抗の温度依存性が飛躍的に改善される、さら
にシャットダウン温度を自由にコントロールできる。エ
チレン−α−オレフィン共重合体の配合割合は、重量平
均分子量が５０万以上の超高分子量ポリオレフィンまた
は組成物の５〜３０重量％であるのが好ましい。The polyethylene copolymer obtained by a metallocene catalyst capable of imparting a low-temperature shutdown function that can be used in the present invention includes linear ethylene polymerized using a single-site catalyst such as a metallocene catalyst. -Α-olefin copolymer, for example, ethylene-butene-1 copolymer, ethylene-hexene-1
Copolymer, ethylene-octene-1 copolymer and the like can be mentioned. The melting point (DSC peak temperature) of the ethylene-α-olefin copolymer is 95 to 125 ° C, preferably 100 to 120 ° C. If the temperature is lower than 95 ° C., the battery characteristics under high-temperature conditions are remarkably deteriorated. If the temperature exceeds 125 ° C., the shutdown function is not exhibited at a preferable temperature. The ratio Mw / Mn (Q value) of the weight average molecular weight Mw to the number average molecular weight Mn of the ethylene / α-olefin copolymer is 1.5 to 3.0, preferably 1.5 to 2.5. Is desirable. This ethylene
By adding an α-olefin copolymer to polyethylene or its polyethylene composition, a function of using a microporous polyethylene membrane as a separator for a lithium battery or the like and shutting down at a low temperature when the electrodes are short-circuited and the temperature inside the battery rises. Is given. Further, the temperature dependency of the film resistance at the time of shutdown is remarkably improved, and the shutdown temperature can be freely controlled. The blending ratio of the ethylene-α-olefin copolymer is preferably 5 to 30% by weight of the ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more or the composition.
【００１８】なお、上述したようなポリオレフィン又は
ポリオレフィン組成物には、必要に応じて、酸化防止
剤、紫外線吸収剤、アンチブロッキング剤、顔料、染
料、無機充填材などの各種添加剤を本発明の目的を損な
わない範囲で添加することができる。The above-mentioned polyolefin or polyolefin composition may be added, if necessary, with various additives such as an antioxidant, an ultraviolet absorber, an antiblocking agent, a pigment, a dye and an inorganic filler according to the present invention. It can be added in a range that does not impair the purpose.
【００１９】２．ポリオレフィン微多孔膜 （1）物性 本発明のポリオレフィン微多孔膜は、次の物性を有して
いる。 空孔率 本発明のポリオレフィン微多孔膜の空孔率は、３５〜９
５％である。特に、イオン透過性を考慮すると、４５〜
９５％が好ましい。空孔率が３５％未満では、ポリオレ
フィン微多孔膜を電池セパレータとして用いた場合に
は、シャットダウンまでの速度が遅くなり好ましくな
く、９５％を超えると、膜の突刺強度自身が低くなりす
ぎて問題である。2. Polyolefin microporous membrane (1) Physical properties The polyolefin microporous membrane of the present invention has the following physical properties. Porosity The porosity of the microporous polyolefin membrane of the present invention is 35 to 9
5%. Particularly, in consideration of ion permeability, 45 to 45
95% is preferred. If the porosity is less than 35%, when the polyolefin microporous membrane is used as a battery separator, the speed up to shutdown is undesirably low, and if it exceeds 95%, the piercing strength of the membrane itself becomes too low. It is.
【００２０】熱収縮率 本発明のポリオレフィン微多孔膜の熱収縮率は、ＭＤ、
ＴＤともに、３％を超えて１５％以下、好ましくは５〜
１５％である。ポリオレフィン微多孔膜を電池セパレー
タとして用いた場合には、熱収縮率が３％以下では、シ
ャットダウンまでの時間が遅くなり過ぎるので好ましく
なく、１５％を超えると形状安定性が悪いため、電極が
露出するという不具合があり、好ましくない。Heat Shrinkage The heat shrinkage of the polyolefin microporous membrane of the present invention is MD,
Both TDs exceed 3% and 15% or less, preferably 5 to
15%. When the microporous polyolefin membrane is used as a battery separator, if the heat shrinkage is 3% or less, the time until shutdown is too long, which is not preferable. If the heat shrinkage exceeds 15%, the shape stability is poor, and the electrode is exposed. This is not preferable because of the disadvantage that
【００２１】突刺強度 本発明のポリオレフィン微多孔膜の突刺強度は、４００
〜６５０ｇ／２５μｍである。突刺強度が４００ｇ／２
５μｍ未満では、ポリオレフィン微多孔膜を電池セパレ
ータとして用いた場合には、電極凹凸やバリによって生
ずるセパレータの圧迫によって破膜が起こりやすく、短
絡が起こりやすい。６５０ｇ／２５μｍ未満を超えると
シャットダウンまでの時間が長くなり問題である。Puncture Strength The puncture strength of the microporous polyolefin membrane of the present invention is 400
６650 g / 25 μm. The piercing strength is 400g / 2
When the thickness is less than 5 μm, when the microporous polyolefin membrane is used as a battery separator, the separator is likely to be ruptured due to pressure on the separator caused by electrode unevenness or burrs, and short-circuit is likely to occur. If it is less than 650 g / 25 μm, the time until shutdown becomes long, which is a problem.
【００２２】バブルポイント 本発明のポリオレフィン微多孔膜のバブルポイントは、
１０ｋｇ／ｃｍ２を超え、好ましくは１５ｋｇ／ｃｍ２
を超えているのが好ましい。バブルポイントが１０ｋｇ
／ｃｍ２以下では、ポリオレフィン微多孔膜を電池セパ
レータとして用いた場合には、孔が大きくなりすぎてデ
ンドライト成長によって電圧降下や自己放電等の不良が
発生するので好ましくない。Bubble Point The bubble point of the microporous polyolefin membrane of the present invention is:
More than 10 kg / cm 2 , preferably 15 kg / cm 2
Is preferably exceeded. 10kg bubble point
/ Cm 2 In the following, the case of using a polyolefin microporous membrane as a battery separator, since holes are defects such as voltage drop and self-discharge caused by dendrite growth too large is not preferable.
【００２３】平均貫通孔径 本発明のポリオレフィン微多孔膜の平均貫通孔径は、好
ましくは０．０１〜０．０５μｍである。平均貫通孔径
が０．０１μｍ未満では、透過性が著しく低下し、０．
０５μｍを超えると電池セパレータとして用いた場合に
デンドライト成長を抑制できない。Average Through-Pore Diameter The average through-pore diameter of the microporous polyolefin membrane of the present invention is preferably 0.01 to 0.05 μm. When the average through-hole diameter is less than 0.01 μm, the permeability is significantly reduced,
If it exceeds 05 μm, dendrite growth cannot be suppressed when used as a battery separator.
【００２４】引張強度 本発明のポリオレフィン微多孔膜の引張強度は、ＭＤ、
ＴＤ方向共に５００ｋｇ／ｃｍ２以上が好ましい。引張
強度が５００ｋｇ／ｃｍ２以上であると、ポリオレフィ
ン微多孔膜を電池セパレータとして用いた場合には、破
膜の心配がなくなる。Tensile Strength The tensile strength of the microporous polyolefin membrane of the present invention is MD,
500 kg / cm 2 or more in both TD directions is preferable. When the tensile strength is 500 kg / cm 2 or more, when a polyolefin microporous film is used as a battery separator, there is no fear of film breakage.
【００２５】本発明のポリオレフィン微多孔膜は、上記
の要件を満たし、収縮率と突刺強度度のバランスがとれ
た微多孔膜であり、発熱した場合に、微孔を閉孔させ、
シャットダウン機能を発揮する点に特徴があり電池用セ
パレータ、液体フィルター等として好適に用いることが
できる。なお、本発明のポリオレフィン微多孔膜は、ポ
リオレフィン微多孔膜を電池セパレータとして用いるに
は、融点におけるシャットダウン時間が、１０秒以下で
あることが好ましい。さらに、電極とセパレータとを８
０℃、１０ｋｇ／ｃｍ２でプレスしたときの剥離強度は
１ｇ以上が好ましく、より好ましくは５ｇ以上である。
この剥離強度が、１ｇ未満であると、電極表面の凹凸に
沿った表面変形によるセパレータの埋まり込みが十分発
揮せず、いわゆるアンカー効果が弱くなり、電極との接
着強度が低下するので好ましくない。剥離強度が５ｇ以
上になると、電極との接着性が良好となり、電極／セパ
レータ間に空隙が出来ずに電極の失活を招かず、また充
放電に伴う電極変形にも追従しやすく、長期に渡って電
極失活を防ぐ機能を有するので特に好ましい。The microporous polyolefin membrane of the present invention satisfies the above requirements and is a microporous membrane having a good balance between shrinkage and piercing strength. When heat is generated, the micropores are closed.
It is characterized by exhibiting a shutdown function and can be suitably used as a battery separator, a liquid filter, and the like. In the polyolefin microporous membrane of the present invention, in order to use the polyolefin microporous membrane as a battery separator, the shutdown time at the melting point is preferably 10 seconds or less. Further, the electrode and the separator are
The peel strength when pressed at 0 ° C. and 10 kg / cm 2 is preferably 1 g or more, more preferably 5 g or more.
If the peel strength is less than 1 g, the separator is not sufficiently embedded due to surface deformation along irregularities on the electrode surface, so-called anchor effect is weakened, and the adhesive strength with the electrode is undesirably reduced. When the peel strength is 5 g or more, the adhesiveness with the electrode becomes good, a gap is not formed between the electrode and the separator, the electrode is not deactivated, and it is easy to follow the electrode deformation due to charge and discharge. It is particularly preferable because it has a function of preventing electrode deactivation over the entire area.
【００２６】（２）ポリオレフィン微多孔膜の製造 本発明のポリオレフィン微多孔膜は、ポリオレフィン又
はポリオレフィン組成物に、必要に応じて低温シャット
ダウン効果を付与するポリマー等を加えた樹脂成分に有
機液状体または固体を混合し、溶融混練後押出成形し、
延伸、溶剤除去、乾燥、熱セットを施すことにより得ら
れる。本発明のポリオレフィン微多孔膜を得る好ましい
方法としては、ポリオレフィン又はポリオレフィン組成
物にポリオレフィンの良溶剤を供給しポリオレフィン又
はポリオレフィン組成物の溶液を調製して、この溶液を
押出機のダイよりシート状に押し出した後、冷却してゲ
ル状組成物を形成して、このゲル状組成物を加熱延伸
し、しかる後残存する溶剤を除去し、乾燥後、熱セット
する方法である。(2) Production of Microporous Polyolefin Membrane The microporous polyolefin membrane of the present invention is obtained by adding an organic liquid or a resin component to a polyolefin or a polyolefin composition and, if necessary, adding a polymer or the like that imparts a low-temperature shutdown effect. Mix solids, extrude after melt kneading,
It can be obtained by stretching, solvent removal, drying and heat setting. As a preferred method of obtaining the polyolefin microporous membrane of the present invention, a good solvent of the polyolefin is supplied to the polyolefin or the polyolefin composition to prepare a solution of the polyolefin or the polyolefin composition, and the solution is formed into a sheet from a die of an extruder. After extrusion, the mixture is cooled to form a gel-like composition, the gel-like composition is heated and stretched, the remaining solvent is removed thereafter, dried, and heat-set.
【００２７】本発明において、原料となるポリオレフィ
ン又はポリオレフィン組成物の溶液は、上述のポリオレ
フィン又はポリオレフィン組成物を、溶剤に加熱溶解す
ることにより調製する。この溶剤としては、ポリオレフ
ィンを十分に溶解できるものであれば特に限定されな
い。例えば、ノナン、デカン、ウンデカン、ドデカン、
流動パラフィンなどの脂肪族または環式の炭化水素、あ
るいは沸点がこれらに対応する鉱油留分などがあげられ
るが、安定なゲル状成形物を得るためには流動パラフィ
ンのような不揮発性の溶剤が好ましい。In the present invention, a solution of a polyolefin or a polyolefin composition as a raw material is prepared by heating and dissolving the above-described polyolefin or polyolefin composition in a solvent. The solvent is not particularly limited as long as it can sufficiently dissolve the polyolefin. For example, Nonan, Decane, Undecane, Dodecane,
Examples include aliphatic or cyclic hydrocarbons such as liquid paraffin, and mineral oil fractions whose boiling points correspond to these.To obtain a stable gel-like molded product, a non-volatile solvent such as liquid paraffin is used. preferable.
【００２８】加熱溶解は、ポリオレフィン又はポリオレ
フィン組成物を溶剤中で完全に溶解する温度で攪拌しな
がら行うか、又は押出機中で均一混合して溶解する方法
で行う。溶剤中で攪拌しながら溶解する場合は、温度は
使用する重合体及び溶剤により異なるが、例えばポリエ
チレン組成物の場合には１４０〜２５０℃の範囲であ
る。ポリオレフィン組成物の高濃度溶液から微多孔膜を
製造する場合は、押出機中で溶解するのが好ましい。The heat dissolution is carried out while stirring the polyolefin or the polyolefin composition at a temperature at which the polyolefin or the polyolefin composition is completely dissolved in the solvent, or by uniformly mixing and dissolving the polyolefin or polyolefin composition in an extruder. In the case of dissolving while stirring in a solvent, the temperature varies depending on the polymer and the solvent to be used. For example, in the case of a polyethylene composition, the temperature is in the range of 140 to 250 ° C. When producing a microporous membrane from a high-concentration solution of the polyolefin composition, it is preferable to dissolve it in an extruder.
【００２９】押出機中で溶解する場合は、まず押出機に
上述したポリオレフィン又はポリオレフィン組成物を供
給し、溶融する。溶融温度は、使用するポリオレフィン
の種類によって異なるが、ポリオレフィンの融点＋３０
〜１００℃が好ましい。例えば、ポリエチレンの場合は
１６０〜２３０℃、特に１７０〜２００℃であるのが好
ましく、ポリプロピレンの場合は１９０〜２７０℃、特
に１９０〜２５０℃であるのが好ましい。次に、この溶
融状態のポリオレフィン又はポリオレフィン組成物に対
して、液状の溶剤を押出機の途中から供給する。When dissolving in an extruder, first, the above-mentioned polyolefin or polyolefin composition is supplied to the extruder and melted. The melting temperature depends on the type of polyolefin used, but the melting point of polyolefin + 30
-100 ° C is preferred. For example, in the case of polyethylene, the temperature is preferably 160 to 230 ° C, particularly 170 to 200 ° C, and in the case of polypropylene, the temperature is preferably 190 to 270 ° C, particularly 190 to 250 ° C. Next, a liquid solvent is supplied to the molten polyolefin or polyolefin composition from the middle of the extruder.
【００３０】ポリオレフィン又はポリオレフィン組成物
と溶剤との配合割合は、ポリオレフィン又はポリオレフ
ィン組成物と溶剤の合計を１００重量％として、ポリオ
レフィン又はポリオレフィン組成物が５〜２５重量％、
好ましくは１０〜２５重量％であり、溶剤が９５〜７５
重量％、好ましくは９０〜７５重量％である。ポリオレ
フィン又はポリオレフィン組成物が５重量％未満では
（溶剤が９５重量％を超えると）、シート状に成形する
際に、ダイス出口で、スウエルやネックインが大きくシ
ートの成形性、自己支持性が困難となり、さらに溶剤の
除去に時間がかかりすぎ、生産性が低下する。一方、ポ
リオレフィン又はポリオレフィン組成物が２５重量％を
超えると（溶剤が７５重量％未満では）、目的とする微
多孔膜が得られず、また成形加工性も低下する。この範
囲において濃度を変えることにより、膜の透過性をコン
トロールすることができる。The mixing ratio of the polyolefin or the polyolefin composition and the solvent is 5 to 25% by weight based on the total of the polyolefin or the polyolefin composition and the solvent being 100% by weight.
Preferably it is 10 to 25% by weight, and the solvent is 95 to 75% by weight.
%, Preferably 90 to 75% by weight. If the polyolefin or the polyolefin composition is less than 5% by weight (the solvent exceeds 95% by weight), when forming into a sheet, the swell and neck-in are large at the die exit, making the sheet formability and self-supporting difficult. In addition, it takes too much time to remove the solvent, and the productivity is reduced. On the other hand, if the content of the polyolefin or the polyolefin composition exceeds 25% by weight (the solvent is less than 75% by weight), a desired microporous film cannot be obtained, and the moldability decreases. By changing the concentration in this range, the permeability of the membrane can be controlled.
【００３１】次に、このようにして溶融混練したポリオ
レフィン又はポリオレフィン組成物の加熱溶液を直接
に、あるいはさらに別の押出機を介して、ダイ等から最
終製品の膜厚が５〜２５０μｍになるように押し出して
成形する。ダイは、通常長方形の口金形状をしたシート
ダイが用いられるが、２重円筒状の中空系ダイ、インフ
レーションダイ等も用いることができる。シートダイを
用いた場合のダイギャップは通常０.１〜５ｍｍであ
り、押し出し成形時には１４０〜２５０℃に加熱する。
この際押し出し速度は、通常２０〜３０ｃｍ/分ないし
１５ｍ／分である。Next, the heated solution of the polyolefin or the polyolefin composition melt-kneaded as described above is directly or through another extruder so that the final product has a thickness of 5 to 250 μm from a die or the like. And extruded. As the die, a sheet die having a rectangular base shape is usually used, but a double cylindrical hollow die, an inflation die, or the like can also be used. The die gap when a sheet die is used is usually 0.1 to 5 mm, and the material is heated to 140 to 250 ° C during extrusion molding.
At this time, the extrusion speed is usually 20 to 30 cm / min to 15 m / min.
【００３２】ダイから押し出された溶液は、冷却するこ
とによりゲル状成形物に形成される。冷却は、ダイを冷
却するか、ゲル状シートを冷却する方法による。冷却は
少なくとも５０℃／分の速度で９０℃以下まで、好まし
くは８０〜３０℃まで行う。ゲル状シートの冷却方法と
しては、冷風、冷却水、その他の冷却媒体に直接接触さ
せる方法、冷媒で冷却したロールに接触させる方法など
を用いることができるが、冷却ロールを用いる方法が好
ましい。The solution extruded from the die is formed into a gel-like molded product by cooling. The cooling is performed by cooling the die or cooling the gel-like sheet. Cooling is performed at a rate of at least 50 ° C / min to 90 ° C or less, preferably to 80 to 30 ° C. As a method of cooling the gel-like sheet, a method of directly contacting with cold air, cooling water, or another cooling medium, a method of contacting with a roll cooled by a refrigerant, and the like can be used, but a method using a cooling roll is preferable.
【００３３】次にこのゲル状成形物を、二軸延伸する。
延伸は、ゲル状成形物を加熱し、通常のテンター法、ロ
ール法、圧延若しくはこれらの方法の組み合わせによっ
て所定の倍率で行う。二軸延伸は、縦横同時延伸または
逐次延伸のいずれでもよいが、特に同時二軸延伸が好ま
しい。延伸温度は、特に制限はないが、より高強度のポ
リオレフィン微多孔膜を得るためには、超高分子量ポリ
エチレンと高密度ポリエチレンとの組成物の場合、１１
０〜１２５℃が好ましく、より好ましくは１１０〜１２
０℃である。延伸倍率は、ＭＤ方向とＴＤ方向に３倍以
上（３×３以上）である。延伸倍率が３倍未満では、ポ
リオレフィン微多孔膜の十分な突刺強度が得られない。Next, this gel-like molded product is biaxially stretched.
The stretching is performed at a predetermined magnification by heating the gel-like molded product and using a usual tenter method, roll method, rolling or a combination of these methods. The biaxial stretching may be either vertical or horizontal simultaneous stretching or sequential stretching, but simultaneous biaxial stretching is particularly preferred. The stretching temperature is not particularly limited, but in order to obtain a higher-strength polyolefin microporous membrane, in the case of a composition of ultra-high-molecular-weight polyethylene and high-density polyethylene, 11
0-125 degreeC is preferable, More preferably, it is 110-12.
0 ° C. The stretching ratio is 3 times or more (3 × 3 or more) in the MD direction and the TD direction. If the stretching ratio is less than 3 times, a sufficient piercing strength of the microporous polyolefin membrane cannot be obtained.
【００３４】さらに、上記で得られた成形物は、溶剤で
洗浄し残留する溶媒を除去する。洗浄溶剤としては、ペ
ンタン、ヘキサン、ヘプタンなどの炭化水素、塩化メチ
レン、四塩化炭素などの塩素化炭化水素、三フッ化エタ
ンなどのフッ化炭化水素、ジエチルエーテル、ジオキサ
ンなどのエーテル類などの易揮発性のものを用いること
ができる。これらの溶剤はポリオレフィン組成物の溶解
に用いた溶媒に応じて適宜選択し、単独もしくは混合し
て用いる。洗浄方法は、溶剤に浸漬し抽出する方法、溶
剤をシャワーする方法、またはこれらの組合せによる方
法などにより行うことができる。上述のような洗浄は、
成形物中の残留溶媒が１重量％未満になるまで行う。そ
の後洗浄溶剤を乾燥するが、洗浄溶剤の乾燥方法は加熱
乾燥、風乾などの方法で行うことができる。Further, the molded product obtained above is washed with a solvent to remove the remaining solvent. Examples of the cleaning solvent include hydrocarbons such as pentane, hexane, and heptane; chlorinated hydrocarbons such as methylene chloride and carbon tetrachloride; fluorinated hydrocarbons such as ethane trifluoride; and ethers such as diethyl ether and dioxane. Volatile ones can be used. These solvents are appropriately selected according to the solvent used for dissolving the polyolefin composition, and used alone or as a mixture. The washing method can be performed by a method of immersing in a solvent for extraction, a method of showering the solvent, a method of a combination thereof, or the like. Cleaning as described above,
The process is performed until the residual solvent in the molded product is less than 1% by weight. Thereafter, the washing solvent is dried, and the washing solvent can be dried by a method such as heat drying or air drying.
【００３５】乾燥して得られた膜は、熱セットの処理に
供される。熱セット温度は、９５℃以上１２１℃以下で
なければならない。超高分子量ポリエチレンと高密度ポ
リエチレン組成物を用いる場合には、１２０℃以下が好
ましく、低温でのシャットダウン機能を付与できるポリ
マー（Ｂ−３）を用いる場合には、９５℃以上１１０℃
以下とすることが好ましい。９５℃未満では透過性が悪
くなりすぎるし、１２１℃を超えると透過性が良くなり
すぎるため、いずれの場合も本発明の目的とする微多孔
膜が得られない。The film obtained by drying is subjected to a heat setting treatment. The heat setting temperature must be between 95 ° C and 121 ° C. When the ultrahigh molecular weight polyethylene and the high-density polyethylene composition are used, the temperature is preferably 120 ° C or lower, and when the polymer (B-3) capable of providing a low-temperature shutdown function is used, the temperature is 95 ° C or higher and 110 ° C or higher.
It is preferable to set the following. If the temperature is lower than 95 ° C., the permeability becomes too poor, and if the temperature exceeds 121 ° C., the permeability becomes too high. In any case, the microporous membrane aimed at by the present invention cannot be obtained.
【００３６】以上のような方法で、上記の物性を有する
ポリオレフィン微多孔膜を製造することができるが、得
られたポリオレフィン微多孔膜は、必要に応じてさら
に、プラズマ照射、界面活性剤含浸、表面グラフト等の
親水化処理などの表面修飾を施すことができる。By the above-mentioned method, a microporous polyolefin membrane having the above-mentioned physical properties can be produced. The obtained microporous polyolefin membrane may be further subjected to plasma irradiation, surfactant impregnation, Surface modification such as hydrophilic treatment such as surface grafting can be performed.
【００３７】[0037]
【実施例】以下に本発明について実施例を挙げてさらに
詳細に説明するが、本発明は実施例に特に限定されるも
のではない。なお、実施例における試験方法は次の通り
である。 （１）重量平均分子量及び分子量分布：ウォーターズ
（株）製のＧＰＣ装置を用い、カラムに東ソー（株）製
ＧＭＨ−６、溶媒にｏ−ジクロロベンゼンを使用し、温
度１３５℃、流量１．０ｍｌ／分にてゲルパーミッショ
ンクロマトグラフィー（ＧＰＣ）法により測定した。 （２）膜厚：触針式膜厚計ミツトヨライトマチックを使
用して測定した。 （３）透気度：ＪＩＳ Ｐ８１１７に準拠して測定し
た。 （４）平均貫通孔径：コールターポロメーター（コール
ター社製）により測定した。 （５）空孔率：重量法により測定した。 （６）突刺強度、引張伸度：直径１ｍｍ（０．５ｍｍ
Ｒ）の針を２ｍｍ／ｓｅｃで突き刺し、破断したときの
荷重を測定した。 （７）引張強度：幅１０ｍｍの短冊状試験片の破断強
度、破断伸度をＡＳＴＭＤ８２２に準拠して測定した。EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not particularly limited to the examples. In addition, the test method in an Example is as follows. (1) Weight average molecular weight and molecular weight distribution: using GPC apparatus manufactured by Waters Co., Ltd., GMH-6 manufactured by Tosoh Corporation, o-dichlorobenzene as a solvent, a temperature of 135 ° C., and a flow rate of 1.0 ml. Per minute by gel permission chromatography (GPC). (2) Film thickness: Measured using a stylus-type film thickness meter Mitutoyolitematic. (3) Air permeability: Measured according to JIS P8117. (4) Average through-hole diameter: Measured with a Coulter porometer (manufactured by Coulter). (5) Porosity: measured by a gravimetric method. (6) Piercing strength, tensile elongation: 1 mm in diameter (0.5 mm
The needle of R) was pierced at 2 mm / sec, and the load at the time of breaking was measured. (7) Tensile strength: The breaking strength and breaking elongation of a 10 mm-wide strip test piece were measured in accordance with ASTM D822.
【００３８】（８）バブルポイント：ＡＳＴＭ Ｅ−１
２８−６１に準拠してエタノール中にて測定した。な
お、限界値を超えている場合には、「≧１５」と記載し
た。 （９）熱収縮率：８０℃雰囲気下で、１２時間暴露した
ときのＭＤ、ＴＤ方向の収縮率を測定した。 （１０）シャットダウン速度：融点温度のプレート上に
セパレータを固定化状態で所定時間保持後に、透気度を
測定し、透気度が１０００００ｓｅｃ以上となるまでの
所用時間で表した。また、セパレータの昇温方法は、オ
イルバスに所定時間挿入する方法をとった。なお、実施
例及び比較例で用いたポリエチレンの融点は、ＤＳＣで
測定したところ１３５℃であった。 （１１）電極剥離強度：電極とセパレータを８０℃、１
０ｋｇ／ｃｍ２でプレス積層して得られた積層膜と電極
との剥離強度を測定した。(8) Bubble point: ASTM E-1
It measured in ethanol according to 28-61. In addition, when exceeding the limit value, it was described as "≧ 15". (9) Thermal shrinkage: The shrinkage in the MD and TD directions when exposed in an atmosphere at 80 ° C. for 12 hours was measured. (10) Shutdown speed: After maintaining the separator in a fixed state on a plate having a melting point temperature for a predetermined time, the air permeability was measured and expressed as a time required until the air permeability became 100,000 sec or more. Further, as a method of raising the temperature of the separator, a method of inserting the separator into an oil bath for a predetermined time was employed. The melting point of polyethylene used in Examples and Comparative Examples was 135 ° C. as measured by DSC. (11) Electrode peel strength: 80 ° C., 1
The peel strength between the laminated film obtained by press lamination at 0 kg / cm 2 and the electrode was measured.
【００３９】実施例１ 重量平均分子量が２．０×１０６の超高分子量ポリエチ
レン（ＵＨＭＷＰＥ）１８重量％と重量平均分子量が
３．５×１０５の高密度ポリエチレン（ＨＤＰＥ）８２
重量％からなるポリエチレン組成物に酸化防止剤をポリ
エチレン組成物１００重量部当たり０．３７５重量部を
加えたポリエチレン組成物を得た。得られたポリエチレ
ン組成物１０重量部を二軸押出機（５８ｍｍφ、Ｌ／Ｄ
＝４２、強混練タイプ）に投入し、この二軸押出機のサ
イドフィーダーから流動パラフィン９０重量部を供給
し、２００℃、２００ｒｐｍで溶融混練して、押出機中
にてポリエチレン溶液を調製し、押出機の先端に設置さ
れたＴダイから最終製品が５０〜６０μｍになるように
押し出し、５０℃に温調された冷却ロールで引き取りな
がら、ゲル状シートを成形した。続いてこのゲル状シー
トを、１１４℃で５×５倍になるように二軸延伸を行い
延伸膜を得た。さらに１１５℃で、１０秒間熱セットを
行いポリエチレン膜を得た。得られた膜を塩化メチレン
で洗浄して残留する流動パラフィンを抽出除去した後、
乾燥を行い厚さ２５μｍのポリエチレン微多孔膜を得
た。このポリエチレン微多孔膜の物性評価の結果を第１
表に示す。EXAMPLE 1 18% by weight of ultra high molecular weight polyethylene (UHMWPE) having a weight average molecular weight of 2.0 × 10 6 and high density polyethylene (HDPE) 82 having a weight average molecular weight of 3.5 × 10 5
A polyethylene composition was obtained by adding 0.375 parts by weight of an antioxidant to 100 parts by weight of the polyethylene composition to the polyethylene composition consisting of 100% by weight. 10 parts by weight of the obtained polyethylene composition was mixed with a twin-screw extruder (58 mmφ, L / D
= 42, strong kneading type), 90 parts by weight of liquid paraffin was supplied from the side feeder of this twin-screw extruder, and melt-kneaded at 200 ° C. and 200 rpm to prepare a polyethylene solution in the extruder. A gel-like sheet was formed while extruding the final product from a T-die set at the tip of the extruder so as to have a thickness of 50 to 60 μm, and taking it off with a cooling roll adjusted to 50 ° C. Subsequently, this gel-like sheet was biaxially stretched at 114 ° C. so as to be 5 × 5 times to obtain a stretched film. Further, heat setting was performed at 115 ° C. for 10 seconds to obtain a polyethylene film. After washing the obtained membrane with methylene chloride to extract and remove the remaining liquid paraffin,
After drying, a 25 μm-thick microporous polyethylene membrane was obtained. The results of evaluation of the physical properties of this polyethylene microporous membrane
It is shown in the table.
【００４０】実施例２〜１５ 表１及び表２に示すＵＨＭＷＰＥとＨＤＰＥを表１及び
表２に示す割合で用い、表１及び表２に示すポリエチレ
ン樹脂濃度、延伸温度、延伸倍率にする以外は、実施例
１と同様にしてポリエチレン微多孔膜を得た。得られた
ポリエチレン微多孔膜の物性を表１及び表２に示す。Examples 2 to 15 UHMWPE and HDPE shown in Tables 1 and 2 were used at the ratios shown in Tables 1 and 2, except that the polyethylene resin concentration, stretching temperature and stretching ratio shown in Tables 1 and 2 were used. A microporous polyethylene membrane was obtained in the same manner as in Example 1. Tables 1 and 2 show the physical properties of the obtained microporous polyethylene membrane.
【００４１】[0041]
【表１】 [Table 1]
【００４２】[0042]
【表２】 [Table 2]
【００４３】実施例１６〜１９ ＵＨＭＷＰＥ、ＨＤＰＥ及びシャットダウン機能を付与
するポリマーとして、ポリエチレンワックス（分子量１
０００、三井ハイワックス−１００Ｐ、融点１１５℃、
三井化学製）、ＬＤＰＥ（ＭＩ＝２ｇ／１０分（１９０
℃、２．１６ｋｇ））、ＬＬＤＰＥ（ＭＩ＝１．５ｇ／
１０分（１９０℃、２．１６ｋｇ））及びシングルサイ
ト触媒を用いて製造したエチレン−α−オレフィン共重
合体（密度０．９１５ｇ／ｃｍ３、融点１２１℃のエチ
レン−オクテン−１共重合体、アフィニティＨＦ１０３
０、ザ・ダウケミカル製）を表３に示す割合で用い、表
３に示すポリエチレン樹脂濃度、延伸温度、延伸倍率に
する以外は、実施例１と同様にしてポリエチレン微多孔
膜を得た。得られたポリエチレン微多孔膜の物性を表３
に示す。Examples 16 to 19 UHMWPE, HDPE and polyethylene wax (molecular weight 1)
000, Mitsui High Wax-100P, melting point 115 ° C,
LDPE (MI = 2 g / 10 min (190
C, 2.16 kg)), LLDPE (MI = 1.5 g /
10 minutes (190 ° C., 2.16 kg) and an ethylene-α-olefin copolymer produced using a single-site catalyst (density 0.915 g / cm 3 , ethylene-octene-1 copolymer having a melting point of 121 ° C.) Affinity HF103
0, manufactured by The Dow Chemical Co., Ltd.) in the proportions shown in Table 3, and a polyethylene microporous membrane was obtained in the same manner as in Example 1 except that the polyethylene resin concentration, stretching temperature and stretching ratio shown in Table 3 were used. Table 3 shows the physical properties of the obtained microporous polyethylene membrane.
Shown in
【００４４】[0044]
【表３】 [Table 3]
【００４５】比較例１〜８ 表４に示すＵＨＭＷＰＥとＨＤＰＥを表４に示す割合で
用い、表４に示す延伸温度、延伸倍率にする以外は、実
施例１と同様にしてポリエチレン微多孔膜を得た。得ら
れたポリエチレン微多孔膜の物性を表４に示す。Comparative Examples 1 to 8 A microporous polyethylene membrane was prepared in the same manner as in Example 1 except that UHMWPE and HDPE shown in Table 4 were used in the proportions shown in Table 4 and the stretching temperature and stretching ratio shown in Table 4 were used. Obtained. Table 4 shows the physical properties of the obtained microporous polyethylene membrane.
【００４６】[0046]
【表４】 [Table 4]
【００４７】[0047]
【発明の効果】以上詳述したように本発明のポリオレフ
ィン微多孔膜は、超高分子量ポリオレフィンからなり、
収縮率と突刺強度のバランスがとれた微多孔膜であり、
電池用セパレータとして用い、発熱した場合に、微孔を
閉孔させ、シャットダウン機能を発揮する点に特徴があ
り、電池特性に優れた安全性の高いポリオレフィン微多
孔膜であり、電池用セパレータ、液体フィルター等とし
て好適に用いることができる。As described in detail above, the microporous polyolefin membrane of the present invention comprises an ultrahigh molecular weight polyolefin,
A microporous membrane that balances shrinkage and piercing strength,
Used as a battery separator, it is characterized in that it closes micropores when it generates heat and exhibits a shutdown function.It is a highly safe microporous polyolefin membrane with excellent battery characteristics. It can be suitably used as a filter or the like.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｈ０１Ｍ 2/16 Ｈ０１Ｍ 2/16 Ｐ // Ｂ２９Ｋ 23:00 105:04 Ｂ２９Ｌ 7:00 (72)発明者 小林 茂明 神奈川県横浜市鶴見区馬場３−27−１− 342 (72)発明者 河野 公一 埼玉県朝霞市三原３−29−10−404 Ｆターム(参考） 4D006 GA16 MA03 MA22 MA24 MA31 MB15 MB16 MB20 MC22 MC22X MC83 MC87 MC88 MC89 NA21 NA36 NA63 NA64 PC80 4F074 AA17 AB01 AD01 AG20 CA03 CB34 CC02X CC32X DA02 DA08 DA22 DA49 4F207 AA03 AA04 AA06 AA11 AA12 AB01 AB06 AG01 AG20 AH33 KA01 KA07 KA17 KF03 KK13 KK65 KL84 KW26 KW41 5H021 BB01 BB02 BB05 BB13 CC00 EE01 EE04 HH00 HH01 HH02 HH06 HH07 ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) H01M 2/16 H01M 2 / 16P // B29K 23:00 105: 04 B29L 7:00 (72) Inventor Shigeaki Kobayashi 3-27-1-342 Baba, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Koichi Kono 3-29-10-404 Mihara, Asaka-shi, Saitama F-term (Reference) 4D006 GA16 MA03 MA22 MA24 MA31 MB15 MB16 MB20 MC22 MC22X MC83 MC87 MC88 MC89 NA21 NA36 NA63 NA64 PC80 4F074 AA17 AB01 AD01 AG20 CA03 CB34 CC02X CC32X DA02 DA08 DA22 DA49 4F207 AA03 AA04 AA06 AA11 AA12 AB01 AB06 AG01 AG20 AH33 KA01 KA07 KA17 KF13 KA17 KF03 KA17 KF03 KK EE01 EE04 HH00 HH01 HH02 HH06 HH07
Claims (5)
量ポリオレフィン（Ａ）又は重量平均分子量５０万以上
の超高分子量ポリオレフィンを含む組成物（Ｂ）からな
るポリオレフィン微多孔膜であって、空孔率が３５〜９
５％、熱収縮率が３％を超えて１５％以下、突刺強度が
４００〜６５０ｇ／２５μｍであることを特徴とするポ
リオレフィン微多孔膜。1. A microporous polyolefin membrane comprising an ultrahigh molecular weight polyolefin (A) having a weight average molecular weight of 500,000 or more or a composition (B) containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more, Porosity 35 to 9
A microporous polyolefin membrane having a heat shrinkage of more than 3% but not more than 15% and a puncture strength of 400 to 650 g / 25 μm.
を用いた電池セパレータ。2. A battery separator using the microporous polyolefin membrane according to claim 1.
を電池セパレータとして用いた電池。3. A battery using the microporous polyolefin membrane according to claim 1 as a battery separator.
を用いたフィルター。4. A filter using the microporous polyolefin membrane according to claim 1.
ポリオレフィン（Ａ）又は重量平均分子量５０万以上の
超高分子量ポリオレフィンを含む組成物（Ｂ）５〜２５
重量％、溶剤９５〜７５重量％からなる溶液を、溶融押
出しによりゲル状物を得、当該ゲル状物を３×３倍以上
に延伸し、しかる後に溶剤を除去、乾燥後、９５℃以上
１２１℃以下にて熱セットを行うことを特徴とする請求
項１記載のポリオレフィン微多孔膜の製造方法。5. An ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more (A) or a composition containing an ultrahigh molecular weight polyolefin having a weight average molecular weight of 500,000 or more (B) 5 to 25.
A solution consisting of 95% to 75% by weight of a solvent is melt-extruded to obtain a gel, and the gel is stretched 3 × 3 times or more, and then the solvent is removed. 2. The method for producing a microporous polyolefin membrane according to claim 1, wherein the heat setting is performed at a temperature of not more than ° C.
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| JP05546199A JP4460668B2 (en) | 1999-03-03 | 1999-03-03 | Polyolefin microporous membrane and method for producing the same |
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| JP2000248093A true JP2000248093A (en) | 2000-09-12 |
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Free format text: JAPANESE INTERMEDIATE CODE: R350 |
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| EXPY | Cancellation because of completion of term |