JPH11255931A - Porous film - Google Patents
Porous filmInfo
- Publication number
- JPH11255931A JPH11255931A JP10320290A JP32029098A JPH11255931A JP H11255931 A JPH11255931 A JP H11255931A JP 10320290 A JP10320290 A JP 10320290A JP 32029098 A JP32029098 A JP 32029098A JP H11255931 A JPH11255931 A JP H11255931A
- Authority
- JP
- Japan
- Prior art keywords
- porous
- porous membrane
- temperature
- film
- porous film
- 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.)
- Pending
Links
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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は気体透過性を有する
多孔質膜に関する。詳しくは、耐熱性を向上させた多孔
質膜を提供するものである。具体的には、濾過膜、電池
セパレ−タ−、通気性を要する各種包装材料、医療材
料、衣料材料等に適した多孔膜を提供することができ、
特に、リチウム二次電池用セパレーターに好適な多孔膜
を提供するものである。The present invention relates to a porous membrane having gas permeability. Specifically, the present invention provides a porous film having improved heat resistance. Specifically, it is possible to provide a porous membrane suitable for filtration membranes, battery separators, various packaging materials requiring air permeability, medical materials, clothing materials, and the like.
In particular, the present invention provides a porous membrane suitable for a separator for a lithium secondary battery.
【０００２】[0002]
【従来の技術】多孔膜は、濾過膜、電池セパレ−タ−、
包装・医療・衣料材料等の様々な工業分野で用いられて
いる。特に、多孔膜をリチウム二次電池用のセパレータ
−として用いる場合には、正負極を直接接触させないよ
うに絶縁（電極の絶縁）しつつ、電解液を保持しイオン
透過性を有する特性が必要とされる。2. Description of the Related Art Porous membranes include filtration membranes, battery separators,
It is used in various industrial fields such as packaging, medical care, and clothing materials. In particular, when the porous film is used as a separator for a lithium secondary battery, it is necessary to have a property of retaining an electrolyte and having ion permeability while insulating the positive and negative electrodes so as not to directly contact them (insulating the electrodes). Is done.
【０００３】また、電池内部での異常反応時などによる
急激な温度上昇に対しては、孔が閉塞することでイオン
透過を停止させ（イオンの絶縁）、安全に電池内部の反
応を停止させることも求められる。これは熱閉塞性と呼
ばれる物性であり、オレフィン系樹脂、例えば、ポリエ
チレンを用いた多孔膜ではその融点近傍の１２０℃から
１３０℃において孔が閉塞する。[0003] In addition, with respect to a rapid temperature rise due to an abnormal reaction inside the battery or the like, the pores are closed to stop the permeation of ions (ion insulation) and safely stop the reaction inside the battery. Is also required. This is a property called heat blocking property. In a porous film using an olefin resin, for example, polyethylene, pores are blocked at 120 ° C. to 130 ° C. near its melting point.
【０００４】この用途には、例えば、特開平６−６８８
６４号公報に見られるような多孔膜を用いることができ
る。該特許では超高分子量ポリエチレンを用いており、
１３０℃付近での孔の閉塞が認められる。すなわち、熱
閉塞性は１３０℃付近で発現し、電池内部の反応を１３
０℃付近で抑止することが可能となる。しかしながら、
電池内部の温度上昇が急激であると、融点よりも遙かに
高い温度になることがあり、この場合、多孔膜が溶融し
て形状を維持できなくなる、或いは膜の残留応力により
亀裂がはいったり破断してしまうといった破膜状態にな
るなどの変化を生じ、絶縁性が損なわれ、再び電池内部
の異常反応が進行する恐れがある。[0004] For this purpose, for example, Japanese Patent Laid-Open No. 6-688
For example, a porous membrane as disclosed in JP-A-64 can be used. The patent uses ultra-high molecular weight polyethylene,
Clogging of the pores around 130 ° C. is observed. That is, the heat occlusive property appears around 130 ° C., and the reaction inside the battery is reduced to 13 ° C.
It becomes possible to suppress the temperature around 0 ° C. However,
If the temperature inside the battery rises rapidly, the temperature may be much higher than the melting point. In this case, the porous membrane will melt and cannot maintain its shape, or cracks will occur due to residual stress in the membrane. A change such as breakage, such as breakage, may occur, insulation properties may be impaired, and abnormal reactions inside the battery may proceed again.
【０００５】かかる温度上昇に対して膜が形状を維持す
ることを耐熱形状維持性と呼び、上記超高分子量ポリエ
チレン製の多孔質膜の場合は、１５０〜１６０℃付近で
破膜する。すなわち、耐熱形状維持性は１６０℃付近よ
りも高い温度で損なわれることになる。更に、ポリプロ
ピレン製セパレーター膜は高温での形状維持性に優れて
いるが、特にリチウム電池セパレーターとして使用する
際、自己閉塞性を発現する温度が約１７５℃であり、リ
チウムの発火温度１８０℃に近接しているという問題が
ある。[0005] Maintaining the shape of the film against such a temperature rise is referred to as heat-resistant shape retention. In the case of the porous film made of ultra-high molecular weight polyethylene, the film breaks at around 150 to 160 ° C. That is, the heat-resistant shape maintaining property is impaired at a temperature higher than around 160 ° C. Furthermore, the polypropylene separator membrane has excellent shape retention at high temperatures, but when used as a lithium battery separator, the temperature at which self-occlusion is exhibited is about 175 ° C, which is close to the ignition temperature of lithium of 180 ° C. There is a problem that you are.
【０００６】一方、セパレーター膜においては、強度向
上のために延伸を行うこともできるが、延伸した膜は耐
熱形状熱特性が低く、ポリエチレン製膜では１５０〜１
６０℃、ポリプロピレン製膜では１８０℃付近で破膜す
る。そこで、耐熱性が高い多孔質膜を得る手段として、
例えば、特公平６−５５８７２号公報あるいは特公平５
−６２１３０号公報，特開平９-２９３４９２に見られ
るように、高耐熱樹脂を用いることが考えられるが、こ
れらの方法では、基本的に閉塞する温度が高く、より早
い時期に異常反応を停止させるという特性、すなわち、
より低い温度での熱閉塞性が損なわれる。On the other hand, the separator membrane can be stretched to improve the strength. However, the stretched membrane has low heat resistance and heat characteristics.
It breaks at around 60 ° C and around 180 ° C with a polypropylene film. Therefore, as a means to obtain a porous film having high heat resistance,
For example, Japanese Patent Publication No. 6-55872 or Japanese Patent Publication No.
As described in JP-A-62130 and JP-A-9-293492, it is conceivable to use a high heat-resistant resin. However, in these methods, the blocking temperature is basically high, and the abnormal reaction is stopped earlier. Property, that is,
Thermal plugging at lower temperatures is compromised.
【０００７】更には、特開平７−２９５６３号公報に
は、耐熱形状維持特性の改善された超高分子量ポリエチ
レン製多孔質膜が記載されているが、これは９０〜１５
０℃の範囲に収まる熱閉塞性と１６０℃以上（条件によ
っては２００℃以上）の耐熱形状維持を有する多孔質膜
であるが、なお十分とは言えない。Further, Japanese Patent Application Laid-Open No. 7-29563 describes a porous membrane made of ultra-high molecular weight polyethylene having improved heat-resistant shape maintaining properties.
Although it is a porous film having a heat blocking property falling within the range of 0 ° C. and maintaining a heat-resistant shape of 160 ° C. or more (200 ° C. or more depending on conditions), it is still insufficient.
【０００８】[0008]
【発明が解決しようとする課題】上述したように、電池
用セパレーターには、特にリチウム二次電池用セパレー
ターについては、温度変化に対しての熱閉塞性と耐熱形
状維持性という二つの特性が特に厳しく求められてお
り、前者はより低い温度で発現し、後者はより高い温度
まで保持されることが要求される。As described above, a battery separator, particularly a lithium secondary battery separator, has two characteristics, namely, heat blocking property against temperature change and heat resistant shape maintaining property. There is a stringent demand, the former occurring at lower temperatures and the latter being required to be maintained at higher temperatures.
【０００９】[0009]
【課題を解決するための手段】そこで、本発明者らは、
従来以上に、温度変化に対しての熱閉塞性と耐熱形状維
持性を向上させるための検討を鋭意実施した結果、多孔
質樹脂基材にプラズマ処理を施すことで製造されるセパ
レーターにおいては、従来の樹脂基材の熱閉塞性を変化
させることなく、一方で、耐熱形状維持性が向上させる
ことができることが見いだし、本発明に到達した。Means for Solving the Problems Accordingly, the present inventors have:
More than ever, as a result of intensive studies to improve the heat blocking property and the heat-resistant shape maintenance property against temperature changes, the separator manufactured by performing plasma treatment on the porous resin It has been found that the heat-resisting shape maintaining property can be improved without changing the heat blocking property of the resin base material, and the present invention has been achieved.
【００１０】すなわち、本発明は、電極の絶縁は従来の
特性を維持しつつ、高温時に溶融したり破膜したりする
ことなく形状を維持し、より高い温度でのイオンの絶縁
を可能にする多孔質膜を提供するものであり、その要旨
は、無機ガスによるプラズマ処理を表面に施した樹脂製
多孔質膜であって、（ａ）厚みが５μｍ以上２００μｍ
以下、（ｂ）空孔率が２０％以上８０％以下、（ｃ）ガ
ーレ式透気度が１０秒／１００ｃｃ以上１５００秒／１
００ｃｃ以下、（ｄ）熱閉塞温度が９０℃以上１６０℃
以下、（ｅ）熱機械分析による膜破断温度が１６０℃以
上３００℃以下で、かつ、前記の熱閉塞温度より１５℃
以上高いこと、を特徴とする多孔質膜、に存する。That is, according to the present invention, while maintaining the conventional characteristics of the electrode, the electrode maintains its shape without melting or breaking at high temperatures, and enables ion insulation at a higher temperature. The present invention provides a porous membrane, the gist of which is a resin-made porous membrane whose surface has been subjected to a plasma treatment with an inorganic gas, and (a) a thickness of 5 μm or more and 200 μm or more.
Hereinafter, (b) the porosity is 20% or more and 80% or less, and (c) the Gurley type air permeability is 10 seconds / 100 cc or more and 1500 seconds / 1.
00cc or less, (d) heat blocking temperature is 90 ° C or more and 160 ° C
Hereinafter, (e) the film breaking temperature by thermomechanical analysis is 160 ° C. or more and 300 ° C. or less, and is 15 ° C. higher than the above-mentioned thermal blocking temperature.
Or higher, the porous membrane characterized in that
【００１１】[0011]
【発明の実施の形態】以下、本発明を更に詳しく説明す
る。本発明に用いる樹脂製多孔質基材の材質は特に制限
はないが、素材の耐久性などから、ポリオレフィン樹
脂、あるいは、フッ素系樹脂が好ましく用いられる。そ
の中では、特に、超高分子量ポリエチレン多孔質膜、ポ
リテトラフルオロエチレン多孔質膜、ポリエチレンやポ
リプロピレンからなる不織布などが用いられる。最も好
ましくは、より低い温度で熱閉塞性を発現する超高分子
量ポリエチレン多孔質膜が用いられる。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The material of the resinous porous substrate used in the present invention is not particularly limited, but a polyolefin resin or a fluorine-based resin is preferably used from the viewpoint of the durability of the material. Among them, a porous ultrahigh molecular weight polyethylene membrane, a polytetrafluoroethylene porous membrane, a nonwoven fabric made of polyethylene or polypropylene, and the like are used. Most preferably, an ultra-high molecular weight polyethylene porous membrane that exhibits heat blocking properties at a lower temperature is used.
【００１２】かかる樹脂製多孔質基材の物性としては、
厚みが５μｍ以上２００μｍ以下で、好ましくは１０μ
ｍ以上５０μｍ以下であり、かつ、空孔率が２０％以上
８０％以下、好ましくは４０％以上６０％以下であるこ
とが望ましい。このような多孔質基材は公知の方法で作
成できる。例えば、超高分子量ポリエチレン多孔質膜の
場合、常温で固体又は液体で、溶融成形条件下で液状で
ある膨潤剤を、超高分子量ポリエチレンに溶融混練し、
該組成物を押し出し成形などの成形方法により製膜し、
膨潤剤を抽出し、必要に応じて、抽出の前もしくは後に
延伸を行うことにより得られる。The physical properties of such a resinous porous substrate include:
The thickness is 5 μm or more and 200 μm or less, preferably 10 μm
m to 50 μm and a porosity of 20% to 80%, preferably 40% to 60%. Such a porous substrate can be prepared by a known method. For example, in the case of an ultra-high molecular weight polyethylene porous membrane, a solid or liquid at room temperature, a swelling agent that is liquid under melt molding conditions is melt-kneaded into ultra-high molecular weight polyethylene,
Film forming the composition by a molding method such as extrusion molding,
It is obtained by extracting the swelling agent and, if necessary, performing stretching before or after the extraction.
【００１３】本発明は上記多孔質樹脂基材にプラズマ処
理を施すことにより、その耐熱性を向上させる点に大き
な特徴を有する。基材表面を適度にプラズマ処理するこ
とにより基材単独では達成し得なかった耐熱性、耐薬品
性などを付与することが可能となる。特に基材表面に該
処理に伴い架橋構造を導入することによりその耐久性は
より優れたものとなる。また、気体の導入量や種類、チ
ャンバー圧力、プラズマ出力などの処理条件を制御する
ことにより、基材表面の官能基生成や表面エネルギーな
どを制御することができる。基材表面へのプラズマ処理
は基材の片面あるいは両面に施こすことができ、そのど
ちらの場合も、もとより存在する基材の孔を実質的に閉
塞させることはない。The present invention has a significant feature in that the heat resistance is improved by subjecting the porous resin substrate to a plasma treatment. By appropriately plasma-treating the substrate surface, it becomes possible to impart heat resistance, chemical resistance, etc., which could not be achieved by the substrate alone. In particular, by introducing a crosslinked structure into the surface of the base material along with the treatment, the durability becomes more excellent. Further, by controlling processing conditions such as the amount and type of gas introduced, chamber pressure, and plasma output, it is possible to control the generation of functional groups and surface energy on the substrate surface. The plasma treatment of the substrate surface can be performed on one or both sides of the substrate, and in either case, the pores of the substrate that originally exist are not substantially closed.
【００１４】プラズマ処理で用いるプラズマソースとし
ては、ラジオ波電源、マイクロ波電源、直流電源等が挙
がられる。また、プラズマ処理としては、通常、適当な
チャンバー内で行われ、その内圧は通常０．１Ｐａ（約
１ｍｍＴｏｒｒ）以上、好ましくは２Ｐａ（約２０ｍｍ
Ｔｏｒｒ）〜４００Ｐａ（約３Ｔｏｒｒ）、特に好まし
くは３Ｐａ（約３０ｍｍＴｏｒｒ）〜１００Ｐａ（約７
５０ｍｍＴｏｒｒ）の範囲の圧力下で放電を行い、プラ
ズマを発生させ、そのプラズマ雰囲気下で基材の処理を
行う。As a plasma source used in the plasma processing, a radio power source, a microwave power source, a DC power source and the like can be mentioned. The plasma treatment is usually performed in an appropriate chamber, and the internal pressure is usually 0.1 Pa (about 1 mmTorr) or more, preferably 2 Pa (about 20 mmTorr).
Torr) to 400 Pa (about 3 Torr), particularly preferably 3 Pa (about 30 mm Torr) to 100 Pa (about 7 Torr).
Discharge is performed under a pressure in the range of 50 mmTorr) to generate plasma, and the substrate is processed in the plasma atmosphere.
【００１５】チャンバー内には、無機ガス、好ましくは
希ガス類（ヘリウム、ネオン、アルゴン、キセノン）、
ハロゲン、窒素、酸素、二酸化炭素、水素などから選ば
れる気体、更に、好ましくは希ガス類のうちから１種又
は２種以上を導入し、必要ならば真空ポンプにて減圧を
行い、適当な圧力に調整する。また、プラズマ処理をす
ることにより得られる多孔質膜の純水に対する接触角
は、プラズマ処理前の基材の接触角よりも通常５度以
上、好ましくは１０度以上小さい値を有することが望ま
しい。このときの接触角は，試料フィルム上に純水の液
滴を形成し、液滴表面と試料フィルムとが交わる点を通
る液滴に対する接線を引きその接線とフィルム面とが形
成する角で液滴を含む方の角度をその試料の純水に対す
る接触角とする。In the chamber, an inorganic gas, preferably a rare gas (helium, neon, argon, xenon),
A gas selected from halogen, nitrogen, oxygen, carbon dioxide, hydrogen, and the like, and more preferably, one or more of rare gases are introduced, and if necessary, the pressure is reduced by a vacuum pump to adjust to an appropriate pressure. I do. Further, it is desirable that the contact angle of the porous membrane obtained by performing the plasma treatment with respect to pure water has a value which is usually at least 5 degrees, preferably at least 10 degrees smaller than the contact angle of the base material before the plasma treatment. The contact angle at this time is to form a droplet of pure water on the sample film, draw a tangent to the droplet passing through the point where the surface of the droplet and the sample film meet, and determine the contact angle between the tangent and the film surface. The angle containing the drop is defined as the contact angle of the sample with pure water.
【００１６】以上のように無機ガスによるプラズマ処理
を表面に施した本発明の樹脂製多孔質膜は、厚みが５μ
ｍ以上２００μｍ以下、好ましくは１０μｍ以上５０μ
ｍ以下であり、かつ、空孔率が２０％以上８０％以下、
好ましくは４０％以上６０％以下である。また、膜のガ
ーレ式透気度は、１０秒／１００ｃｃ以上１５００秒／
１００ｃｃ以下、好ましくは１０秒／１００ｃｃ以上１
０００秒／１００ｃｃ以下である。以上の膜の厚みと空
孔率は、多孔質基材の厚さ、空孔率と実質的に同じ範囲
にあることが好ましく、かかる範囲をはずれると、電池
セパレーターとしての利用が難しくなるので好ましくな
い。As described above, the resin porous membrane of the present invention, whose surface has been subjected to the plasma treatment with an inorganic gas, has a thickness of 5 μm.
m to 200 μm, preferably 10 μm to 50 μm
m and a porosity of 20% or more and 80% or less,
Preferably it is 40% or more and 60% or less. Gurley air permeability of the membrane is 10 seconds / 100 cc or more and 1500 seconds /
100 cc or less, preferably 10 seconds / 100 cc or more 1
000 seconds / 100 cc or less. The thickness and porosity of the above-described film are preferably in the same range as the thickness of the porous substrate and the porosity.If the porosity is outside the above range, it becomes difficult to use the battery as a battery separator. Absent.
【００１７】また、該多孔質膜の熱閉塞温度が９０℃以
上１６０℃以下である一方、熱機械分析による膜破断温
度が１６０℃以上３００℃以下で、かつ、前記の熱閉塞
温度より１５℃以上高い温度であり、電池用セパレータ
ーとして、特にリチウム二次電池用セパレーターとして
極めて優れた特性を具備する。ここでいう熱機械分析と
は一般にThermal Mechanical Analysys（TMA)と呼ばれ
る分析法で，試料片に一定の荷重をかけながら雰囲気温
度を変化させ、試料片の熱変化による挙動を調べるもの
である。本願では、試料片に１ｇ重の一定の荷重をかけ
つつ雰囲気温度を室温から毎分５℃の速度で上昇させ、
試料片が破断する温度を、熱的機械分析による膜破断温
度とした。Further, while the heat blocking temperature of the porous film is 90 ° C. or more and 160 ° C. or less, the film breaking temperature by thermomechanical analysis is 160 ° C. or more and 300 ° C. or less and 15 ° C. The temperature is as high as above, and it has extremely excellent characteristics as a battery separator, particularly as a lithium secondary battery separator. The thermomechanical analysis referred to here is an analysis method generally called Thermal Mechanical Analysys (TMA) in which the ambient temperature is changed while applying a constant load to the sample, and the behavior of the sample due to the thermal change is examined. In the present application, while applying a constant load of 1 g weight to the sample piece, the ambient temperature is increased from room temperature at a rate of 5 ° C. per minute,
The temperature at which the sample piece broke was defined as the film breaking temperature by thermal mechanical analysis.
【００１８】本発明の多孔質膜をセパレーターとして用
いたリチウム二次電池では、例えば、負極としてリチウ
ム金属、リチウムとアルミニウム等との合金、あるいは
リチウムイオンを吸収、放出できるようにした炭素電極
などが用いられ、正極としては二酸化マンガン等の公知
の電極が用いられる。電池の形状としては、例えば、本
発明の多孔質膜を正極と負極との間に巻き込んだもの、
あるいは各電極を袋状にした多孔質膜に包みこんだもの
等を電解液と共にケースに収納して密閉された電池が例
示できる。電解液としては、例えば、エチレンカーボネ
ート（ＥＣ）、ジメチルカーボネート（ＤＭＣ）などの
非プロトン性極性溶媒にＬｉＰＦ6など電解質を溶かし
た非水溶液が用いられる。In a lithium secondary battery using the porous membrane of the present invention as a separator, for example, a lithium metal, an alloy of lithium and aluminum, or a carbon electrode capable of absorbing and releasing lithium ions is used as a negative electrode. A known electrode such as manganese dioxide is used as the positive electrode. As the shape of the battery, for example, those in which the porous membrane of the present invention is wound between the positive electrode and the negative electrode,
Alternatively, a battery in which each electrode is wrapped in a bag-shaped porous membrane and the like are housed in a case together with an electrolytic solution, and a sealed battery can be exemplified. As the electrolyte, for example, a non-aqueous solution in which an electrolyte such as LiPF 6 is dissolved in an aprotic polar solvent such as ethylene carbonate (EC) or dimethyl carbonate (DMC) is used.
【００１９】[0019]
【実施例】本発明を実施例により具体的に説明するが、
本発明はその要旨を越えない限り、以下の実施例に限定
されるものではない。なお、以下の諸例において、各測
定は次の方法によった。EXAMPLES The present invention will be described specifically with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist. In addition, in the following examples, each measurement was based on the following method.
【００２０】（１）透気度 ＪＩＳ Ｐ８１１７に従って測定した。測定機材は、東
洋精機社製Ｂ型ガーレ式デンソーメータ（商品名）を用
いた。 （２）空孔率 膜の体積と重量および材料の密度から、膜内部に占める
空孔部分（材料のない空間）の体積を百分率で表した。(1) Air permeability Measured according to JIS P8117. As a measuring device, a B-type Gurley type densometer (trade name) manufactured by Toyo Seiki Co., Ltd. was used. (2) Porosity From the volume and weight of the film and the density of the material, the volume of the void portion (space without material) occupying the inside of the film was expressed in percentage.
【００２１】（３）熱的機械分析 試料（多孔質膜）を幅４ｍｍ、長さ１０ｍｍの短冊状に
切り出し、その試料片に１ｇ重の一定の荷重をかけつつ
雰囲気温度を室温から毎分５℃の速度で上昇させ、試料
片が破断する温度を、熱的機械分析による膜破断温度と
した。(3) Thermal Mechanical Analysis A sample (porous membrane) was cut into a strip having a width of 4 mm and a length of 10 mm, and the temperature of the sample was changed from room temperature to 5 min. The temperature at which the sample was broken at a rate of ° C. was defined as a film breaking temperature by thermal mechanical analysis.
【００２２】（４）熱閉塞試験 厚み２ｍｍで、外形が幅、長さとも８０ｍｍの正方形状
で中央に幅、長さとも４０ｍｍの正方形状の孔を有する
アルミ板２枚で、上下から同じ外形寸法のサンプルを挟
み、さらに外周をクリップで固定する。なお、サンプル
が直接アルミ板に接触しないように、アルミ板と同じ外
形寸法の厚み１００μｍテフロンフィルムをサンプル両
面に挟み込んだ。これをオーブン内に置きオーブン温度
を９０℃から５℃毎に上昇させ、各温度で３０分間静置
した後、取り出して透気度を測定した。透気度の測定を
開始して１時間以上経ても空気が透過が１０ｃｃ未満の
ものは閉塞と判定し、その温度を膜の閉塞温度とした。(4) Thermal blockage test Two aluminum plates having a thickness of 2 mm and an outer shape of 80 mm in width and length and having a square hole of 40 mm in width and 40 mm in length at the center, and the same outer shape from above and below The sample of the dimensions is sandwiched, and the outer periphery is further fixed with clips. A 100 μm thick Teflon film having the same external dimensions as the aluminum plate was sandwiched between both sides of the sample so that the sample did not directly contact the aluminum plate. This was placed in an oven, and the temperature of the oven was increased from 90 ° C. every 5 ° C., allowed to stand at each temperature for 30 minutes, taken out, and the air permeability was measured. If the air permeability was less than 10 cc even after one hour or more from the start of the measurement of the air permeability, the air was judged to be clogged, and the temperature was defined as the membrane blocking temperature.
【００２３】（５）接触角測定 試料フィルム上に純水の液滴を形成し、液滴表面と試料
フィルムとが交わる点を通る液滴に対する接線を引きそ
の接線とフィルム面とが形成する角で液滴を含む方の角
度をその試料の純水に対する接触角とした。(5) Measurement of Contact Angle A droplet of pure water is formed on a sample film, a tangent to a droplet passing through a point where the droplet surface and the sample film intersect is drawn, and the angle formed by the tangent and the film surface. The angle of the sample containing the droplet was defined as the contact angle of the sample with pure water.
【００２４】比較例１ 粘度平均分子量が２３０万であるポリエチレン２０重量
％に対してステアリルアルコール８０重量％をパウダー
ブレンドした後、１７０℃のオーブン中に３０分間放置
し、ポリエチレンをアルコールで湿潤させた。この際混
合物１００重量部に対して０．５重量部のフェノール系
安定剤を添加した。この混合物を温度１７０℃、回転数
１００ｒｐｍの条件で１０分間混練りした。樹脂温は１
８５℃で一定、トルクも一定であり、混合物は溶融状態
で透明であり均一であった。COMPARATIVE EXAMPLE 1 After 20% by weight of polyethylene having a viscosity average molecular weight of 2.3 million was blended with 80% by weight of stearyl alcohol, the mixture was allowed to stand in an oven at 170 ° C. for 30 minutes to wet the polyethylene with alcohol. . At this time, 0.5 part by weight of a phenolic stabilizer was added to 100 parts by weight of the mixture. This mixture was kneaded for 10 minutes at a temperature of 170 ° C. and a rotation speed of 100 rpm. Resin temperature is 1
The mixture was constant at 85 ° C., the torque was constant, and the mixture was transparent and homogeneous in the molten state.
【００２５】該均一混合物が冷却固化する前に１７０℃
の温度でプレス成形し０．５ｍｍのプレスシートを得
た。該シートを、二軸延伸機を用い１２０℃の温度で２
００％／ｓｅｃで縦横同時に、４×４倍の延伸を行っ
た。延伸後のシートを６０℃のイソプロパノール中に５
分間浸漬しステアリルアルコールを抽出した。このシー
トは多孔化のため白色を示した。かくして得られた多孔
質樹脂膜の性質を表−１、表−２に示す。 比較例２ 粘度平均分子量が２３０万である超高分子量ポリエチレ
ン１８重量％に対してステアリルアルコール８２重量部
とフェノール系添加物０．５重量部をパウダーブレンド
した後、水冷ジャケットで供給部を冷却した５０ｍｍφ
押出機に供給し、この先端に更に４０ｍｍφ押出機を付
設して２１０℃で溶融混合し、均一な溶融体にした。Before the homogeneous mixture cools and solidifies,
At a temperature of 0.5 mm to obtain a 0.5 mm pressed sheet. The sheet is subjected to a biaxial stretching at a temperature of 120 ° C. for 2 hours.
Stretching 4 × 4 times was performed at the same time at 00% / sec. The stretched sheet is placed in isopropanol at 60 ° C. for 5 minutes.
It was immersed for a minute to extract stearyl alcohol. This sheet was white due to porosity. The properties of the porous resin film thus obtained are shown in Tables 1 and 2. Comparative Example 2 82 parts by weight of stearyl alcohol and 0.5 part by weight of a phenolic additive were powder-blended to 18% by weight of ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 2.3 million, and the supply unit was cooled with a water cooling jacket. 50mmφ
The mixture was supplied to an extruder, and a 40 mmφ extruder was further attached to the end of the extruder. The extruder was melted and mixed at 210 ° C. to obtain a uniform melt.
【００２６】該均一混合物を幅５５０ｍｍ、ダイクリア
ランス０．３ｍｍのＴダイより押し出し、更にドラフト
率１．８で引き取ることにより厚さ０．１５ｍｍのシー
トを得た。このシートからステアリルアルコールを６０
℃のイソプロパノールで抽出除去して多孔性シートを得
た。該シートを、ロール延伸機を用い１００℃で縦方向
に３．０倍延伸し、続いてテンター延伸機を用い１３０
℃で横方向に５．５倍延伸を行った。得られた多孔質樹
脂膜の性質を表−１、表−２に示す。The homogenous mixture was extruded from a T-die having a width of 550 mm and a die clearance of 0.3 mm, and was further drawn at a draft rate of 1.8 to obtain a sheet having a thickness of 0.15 mm. 60% stearyl alcohol from this sheet
Extraction and removal with isopropanol at ℃ resulted in a porous sheet. The sheet is stretched 3.0 times in the machine direction at 100 ° C. using a roll stretching machine, and then stretched 130 times using a tenter stretching machine.
The film was stretched 5.5 times in the transverse direction at ℃. The properties of the obtained porous resin film are shown in Tables 1 and 2.
【００２７】実施例１ 平行平板型電極を内部にもつチャンバー内に上述の比較
例１で得た超高分子量ポリエチレン多孔膜を置き、チャ
ンバーを充分排気した後アルゴンガスを導入してチャン
バー圧を２０Ｐａに保った。１３．５６ＭＨｚのラジオ
波電源により放電を開始し、４０Ｗの出力で１分間処理
を行った。得られた多孔膜の物性を表−１、表−２に示
す。Example 1 The ultrahigh molecular weight polyethylene porous film obtained in Comparative Example 1 was placed in a chamber having a parallel plate type electrode inside, and the chamber was sufficiently evacuated. Kept. Discharge was started by a 13.56 MHz radio wave power supply, and processing was performed for 1 minute at an output of 40 W. The physical properties of the obtained porous membrane are shown in Tables 1 and 2.
【００２８】実施例２ 実施例１においてアルゴンの代わりにヘリウムを用いた
以外は実施例１と同様に処理を行って多孔膜を得た。得
られた多孔膜の物性を表−１、表−２に示す。 実施例３ 実施例１においてアルゴンの代わりに窒素を用いた以外
は実施例１と同様に処理を行って多孔膜を得た。得られ
た多孔膜の物性を表−１、表−２に示す。 実施例４ 比較例２で得た多孔性フィルムを幅３０ｃｍ、長さ２５
ｃｍの並行平板電極を内部に持つチャンバー内に入れチ
ャンバーを充分に排気した後、アルゴンガスと酸素ガス
をそれぞれ毎分１０ｃｃおよび３０ｃｃの割合で導入し
ながらチャンバー内を約４０Ｐａに保った。１３．５６
ＭＨｚのラジオ波電源により１０Ｗの出力で放電を開始
して該多孔性フィルムを並行平板電極間を連続的に通過
させ、処理を行った。フィルムが電極間を通過するのに
要した時間は３０秒である。得られた多孔質膜の物性を
表−１、表−２に示す。Example 2 A porous film was obtained in the same manner as in Example 1 except that helium was used instead of argon. The physical properties of the obtained porous membrane are shown in Tables 1 and 2. Example 3 A porous membrane was obtained in the same manner as in Example 1 except that nitrogen was used instead of argon. The physical properties of the obtained porous membrane are shown in Tables 1 and 2. Example 4 The porous film obtained in Comparative Example 2 was 30 cm wide and 25 cm long.
After placing the inside of a chamber having a parallel plate electrode having a diameter of 10 cm and exhausting the chamber sufficiently, the inside of the chamber was maintained at about 40 Pa while introducing argon gas and oxygen gas at a rate of 10 cc and 30 cc per minute, respectively. 13.56
Discharge was started at an output of 10 W with a radio frequency power supply of MHz, and the porous film was continuously passed between parallel plate electrodes to perform processing. The time required for the film to pass between the electrodes is 30 seconds. The physical properties of the obtained porous membrane are shown in Tables 1 and 2.
【００２９】以上の実施例は、比較例に対して、耐熱形
状維持性が向上することが認められると共に、熱閉塞す
る特性は維持されていることが判明した。In the above examples, it was confirmed that the heat-resistant shape maintenance property was improved as compared with the comparative example, and it was found that the heat-closing property was maintained.
【００３０】[0030]
【表１】 [Table 1]
【００３１】[0031]
【表２】 [Table 2]
【００３２】[0032]
【発明の効果】本発明によれば、従来の樹脂基材の熱閉
塞性を変化させることなく、一方で、耐熱形状維持性が
向上した多孔質膜が提供される。その結果として、本発
明の多孔質膜は、電池用セパレーターとして、特にリチ
ウム二次電池用セパレーターとして有用である。According to the present invention, it is possible to provide a porous film having improved heat-resistant shape retention without changing the conventional heat blocking property of a resin substrate. As a result, the porous membrane of the present invention is useful as a battery separator, particularly as a lithium secondary battery separator.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｈ０１Ｍ 10/40 Ｈ０１Ｍ 10/40 Ｚ // Ｂ２９Ｋ 23:00 27:12 105:04 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification symbol FI H01M 10/40 H01M 10/40 Z // B29K 23:00 27:12 105: 04
Claims (7)
した樹脂製多孔質膜であって、（ａ）厚みが５μｍ以上
２００μｍ以下、（ｂ）空孔率が２０％以上８０％以
下、（ｃ）ガーレ式透気度が１０秒／１００ｃｃ以上１
５００秒／１００ｃｃ以下、（ｄ）熱閉塞温度が９０℃
以上１６０℃以下、（ｅ）熱機械分析による膜破断温度
が１６０℃以上３００℃以下で、かつ、前記の熱閉塞温
度より１５℃以上高いこと、を特徴とする多孔質膜。1. A resinous porous film having a surface subjected to plasma treatment with an inorganic gas, comprising: (a) a thickness of 5 μm to 200 μm; (b) a porosity of 20% to 80%; ) Gurley type air permeability is 10 seconds / 100cc or more 1
500 seconds / 100 cc or less, (d) heat blocking temperature is 90 ° C.
(E) a porous film having a film breaking temperature by thermomechanical analysis of 160 ° C. to 300 ° C. and 15 ° C. or more higher than the above-mentioned thermal blocking temperature.
希ガス類、ハロゲンガス、窒素、酸素、水素、二酸化炭
素から選ばれる１種または２種以上の気体を導入し、該
雰囲気下０．１Ｐａ以上の圧力下で放電を行うものであ
ることを特徴とする請求項１記載の多孔質膜。2. A plasma processing method comprising the steps of:
One or more gases selected from rare gases, halogen gases, nitrogen, oxygen, hydrogen, and carbon dioxide are introduced, and discharge is performed under a pressure of 0.1 Pa or more in the atmosphere. The porous membrane according to claim 1.
多孔質膜の純水に対する接触角が処理前の基材の接触角
よりも５度以上小さい値を有することを特徴とする請求
項１又は２のいずれかに記載の多孔質膜。3. The method according to claim 1, wherein the contact angle of the porous membrane obtained by the plasma treatment with pure water has a value smaller than the contact angle of the base material before the treatment by at least 5 degrees. The porous membrane according to any one of the above.
ことを特徴とする請求項１ないし３のいずれかに記載の
多孔質膜。4. The porous membrane according to claim 1, wherein the porous substrate is a polyolefin resin.
を特徴とする請求項１ないし３のいずれかに記載の多孔
質膜。5. The porous membrane according to claim 1, wherein the porous substrate is a fluorine-containing resin.
膜からなることを特徴とする電池セパレータ−。6. A battery separator comprising the porous membrane according to any one of claims 1 to 5.
み込んでなることを特徴とするリチウム二次電池。7. A lithium secondary battery comprising the battery separator according to claim 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10320290A JPH11255931A (en) | 1998-01-08 | 1998-11-11 | Porous film |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP217498 | 1998-01-08 | ||
| JP10-2174 | 1998-01-08 | ||
| JP10320290A JPH11255931A (en) | 1998-01-08 | 1998-11-11 | Porous film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11255931A true JPH11255931A (en) | 1999-09-21 |
Family
ID=26335511
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10320290A Pending JPH11255931A (en) | 1998-01-08 | 1998-11-11 | Porous film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11255931A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002046282A1 (en) * | 2000-12-07 | 2002-06-13 | Exxonmobil Oil Corporation | Plasma treated porous film |
| JP2009510689A (en) * | 2005-09-30 | 2009-03-12 | コンスタンティノビッチ フィリポフ、アレクサンドル | Carbon-containing material and lithium ion storage battery for lithium ion storage battery |
-
1998
- 1998-11-11 JP JP10320290A patent/JPH11255931A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002046282A1 (en) * | 2000-12-07 | 2002-06-13 | Exxonmobil Oil Corporation | Plasma treated porous film |
| JP2009510689A (en) * | 2005-09-30 | 2009-03-12 | コンスタンティノビッチ フィリポフ、アレクサンドル | Carbon-containing material and lithium ion storage battery for lithium ion storage battery |
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