JP3507092B2 - Porous film, its production method and its use - Google Patents

Porous film, its production method and its use

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Publication number
JP3507092B2
JP3507092B2 JP00263693A JP263693A JP3507092B2 JP 3507092 B2 JP3507092 B2 JP 3507092B2 JP 00263693 A JP00263693 A JP 00263693A JP 263693 A JP263693 A JP 263693A JP 3507092 B2 JP3507092 B2 JP 3507092B2
Authority
JP
Japan
Prior art keywords
temperature
film
porous film
porous
stretching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP00263693A
Other languages
Japanese (ja)
Other versions
JPH05331306A (en
Inventor
浩之 樋口
喜一郎 松下
実 江副
俊彦 篠村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority to JP00263693A priority Critical patent/JP3507092B2/en
Priority to DE69304587T priority patent/DE69304587T2/en
Priority to EP19930105193 priority patent/EP0565938B1/en
Priority to US08/039,907 priority patent/US5385777A/en
Publication of JPH05331306A publication Critical patent/JPH05331306A/en
Application granted granted Critical
Publication of JP3507092B2 publication Critical patent/JP3507092B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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

  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Cell Separators (AREA)

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は多孔質フィルム、その製
造法、その多孔質フィルムから成る電池用セパレータお
よびこのセパレータを組み込んだ電池に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous film, a method for producing the same, a battery separator comprising the porous film and a battery incorporating the separator.

【０００２】[0002]

【従来の技術】種々のタイプの電池が実用に供されてお
り、これら電池には正負両極の短絡防止のために該両極
間にセパレータが介在させられる。2. Description of the Related Art Various types of batteries have been put to practical use, and a separator is interposed between the two electrodes to prevent short circuit between the positive and negative electrodes.

【０００３】最近、電子機器のコードレス化等に対応す
るための電池として、高エネルギー密度、高起電力、自
己放電の少なさからリチウム電池が注目を浴びている。Recently, a lithium battery has been attracting attention as a battery for adapting to cordless electronic devices and the like because of its high energy density, high electromotive force, and low self-discharge.

【０００４】リチウム電池としては、例えば、負極を金
属リチウム、リチウムとアルミニウム等の金属との合
金、カーボンやグラファイト等のリチウムイオンを吸着
する能力またはインターカレーションにより吸蔵する能
力を有する有機材料、あるいはリチウムイオンをドーピ
ングした導電性高分子で形成したもの等が知られてい
る。As the lithium battery, for example, an organic material having a negative electrode such as metallic lithium, an alloy of lithium and a metal such as aluminum, an ability to adsorb lithium ions such as carbon and graphite, or an ability to occlude by intercalation, or Those formed of a conductive polymer doped with lithium ions are known.

【０００５】また、正極としても種々の材料が提案さ
れ、例えば、一般に（ＣＦｘ）ｎで示されるフッ化黒
鉛、ＭｎＯ2 、Ｖ2 Ｏ5 、ＣｕＯ、Ａｇ2 ＣｒＯ4 等の
金属酸化物、ＴｉＯ2 、ＣｕＳ等の硫化物等が知られて
いる。Various materials have been proposed for the positive electrode. For example, fluorinated graphite generally represented by (CFx) n, metal oxides such as MnO 2 , V 2 O 5 , CuO and Ag 2 CrO 4 , and TiO 2. 2. Sulfides such as CuS are known.

【０００６】そして、このリチウム電池は負極構成材料
としてのリチウムが強い反応性を有し、また、エチレン
カーボネート、プロピレンカーボネート、アセトニトリ
ル、γ−ブチロラクトン、１，２−ジメキシエタン、テ
トラヒドロフラン等の有機溶媒にＬｉＰＦ6 、ＬｉＣＦ
3 ＳＯ3 、ＬｉＣｌＯ4 、ＬｉＢＦ4 等を電解質として
溶解した有機溶媒系の電解液を使用しているので、外部
短絡や誤接続等により異常電流が流れた場合、これに伴
って電池温度が著しく上昇し、それを組み込んだ機器に
熱的ダメージを与える懸念がある。In this lithium battery, lithium as a negative electrode constituent material has a strong reactivity, and the organic solvent such as ethylene carbonate, propylene carbonate, acetonitrile, γ-butyrolactone, 1,2-dimexiethane, tetrahydrofuran, etc. is used as LiPF. 6 , LiCF
3 SO 3 , LiClO 4 , LiBF 4, etc. are used as electrolytes. Since an organic solvent-based electrolyte is used, if an abnormal current flows due to an external short circuit or incorrect connection, the battery temperature will increase significantly. There is a concern that it will rise and cause thermal damage to equipment incorporating it.

【０００７】かような危険を回避するため、ポリエチレ
ン（以下、「ＰＥ」と称す）多孔質フィルムあるいはポ
リプロピレン（以下、「ＰＰ」と称す）多孔質フィルム
をセパレータとして用いること（特開昭６０−２３９５
４号公報、特開平２−７５１５１号公報）、通常の分子
量を有するＰＥと高分子量ＰＥの混合物から成る多孔質
フィルムをセパレータとすること（特開平２−２１５５
９号公報）、あるいは材質の異なる多孔質フィルムを重
ね合わせてセパレータとすること（特開昭６２−１０８
５７号公報、特開昭６３−３０８８６６号公報）が提案
されている。In order to avoid such a danger, a polyethylene (hereinafter referred to as "PE") porous film or a polypropylene (hereinafter referred to as "PP") porous film is used as a separator (JP-A-60- 2395
No. 4, JP-A-2-75151), using a porous film composed of a mixture of PE having a normal molecular weight and high molecular weight PE as a separator (JP-A-2-2155).
No. 9), or by stacking porous films made of different materials to form a separator (JP-A-62-108).
57 and JP-A-63-308866) have been proposed.

【０００８】このような多孔質フィルムを単独あるいは
重ね合わせてセパレータとする意図は、正常通電時には
正極と負極の間に位置してこれら両極の短絡を防止する
と共に、その多孔質構造により両極間の電気抵抗を低く
抑えて電池電圧を維持し、一方、異常電流により電池の
内部温度が上昇した場合には、所定温度で多孔質構造か
ら無孔質構造に変質させることにより、その電気抵抗を
増大させて電池反応を遮断し、過度の温度上昇を防止し
て安全を確保しようとすることにある。The intention of using such a porous film alone or as a laminate to form a separator is to position it between the positive electrode and the negative electrode at the time of normal energization to prevent short-circuiting between these electrodes, and due to its porous structure, to provide a space between both electrodes. If the internal temperature of the battery rises due to an abnormal current while keeping the battery voltage by keeping the electrical resistance low, the electrical resistance is increased by changing the porous structure to a non-porous structure at a predetermined temperature. This is to prevent the battery reaction and prevent excessive temperature rise to ensure safety.

【０００９】異常電流による温度の上昇があった場合、
電気抵抗の増大により電池反応を遮断することにより温
度の過昇を防止して電池の安全を確保する機能を一般に
シャットダウン（Ｓｈｕｔ−ｄｏｗｎ、以下、「ＳＤ」
と称す）と呼び、リチウム電池用セパレータ等には必須
の機能である。When the temperature rises due to an abnormal current,
Shut-down (hereinafter referred to as "SD") is generally used for shutting down a function of preventing excessive temperature rise by shutting down a battery reaction due to an increase in electric resistance and ensuring battery safety.
It is an essential function for a lithium battery separator or the like.

【００１０】そして、本明細書においては電気抵抗が増
大し、その値が２００Ω・ｃｍ2 に達した際の温度を、
以下、「ＳＤ開始温度」と称することとする。ＳＤ開始
温度が低すぎる場合は僅かな温度上昇で電気抵抗の増大
が開始されることになり実用性に乏しく、高過ぎる場合
は安全性の確保が不十分となる。現在のところ、このＳ
Ｄ開始温度は約１１０〜１６０℃が好ましい（より好ま
しくは約１２０〜１５０℃）と認識されている。In the present specification, the temperature when the electric resistance increases and the value reaches 200 Ω · cm 2 ,
Hereinafter, it will be referred to as "SD start temperature". If the SD start temperature is too low, the increase in electrical resistance will start with a slight temperature rise, which is impractical, and if it is too high, safety will be insufficient. Currently, this S
It is recognized that the D onset temperature is preferably about 110 to 160 ° C (more preferably about 120 to 150 ° C).

【００１１】更に、電池用セパレータは増大した電気抵
抗が適当な温度まで維持されることが安全性確保の点か
ら望ましい。増大した電気抵抗が維持される上限温度を
以下、「耐熱温度」と称することとし、また、ＳＤ開始
温度から耐熱温度までの温度幅（即ち、耐熱温度とＳＤ
開始温度との温度差）を「耐熱温度幅」と称することと
する。Furthermore, it is desirable from the viewpoint of ensuring safety that the increased electrical resistance of the battery separator is maintained at an appropriate temperature. Hereinafter, the upper limit temperature at which the increased electrical resistance is maintained will be referred to as “heat resistant temperature”, and the temperature range from the SD start temperature to the heat resistant temperature (that is, heat resistant temperature and SD
The temperature difference from the starting temperature) will be referred to as the "heat-resistant temperature range".

【００１２】この耐熱温度はセパレータのフィルム形状
維持機能ともみることができ、温度の過昇によってセパ
レータが溶融するとフィルム形状を維持できずに破れを
生じ、電気抵抗は減少しＳＤ機能は喪失される。そし
て、ＳＤ機能が喪失されると、リチウム電池内において
正極と負極が接触短絡して温度が急激に上昇し、それを
組み込んだ機器に熱的ダメージを与えるという懸念があ
る。従って、電池用セパレータには安全性を確保する点
から、約１１０〜１６０℃の範囲内にＳＤ開始温度を有
し、耐熱温度が高く且つ耐熱温度幅が広いことが望まれ
るのである。This heat-resistant temperature can also be regarded as a function of maintaining the film shape of the separator. When the separator melts due to excessive temperature rise, the film shape cannot be maintained and breaks, the electrical resistance decreases and the SD function is lost. . Then, if the SD function is lost, there is a concern that the positive electrode and the negative electrode are short-circuited in the lithium battery due to contact with each other and the temperature rises rapidly, which causes thermal damage to a device incorporating the same. Therefore, from the viewpoint of ensuring safety, it is desirable for the battery separator to have an SD start temperature within a range of about 110 to 160 ° C., a high heat resistant temperature and a wide heat resistant temperature range.

【００１３】以上述べたＳＤ特性の他に、基本的な特性
として電池用セパレータには電気抵抗値が低いこと、引
張弾性率等の機械的強度が高いこと、フィルムとして厚
さムラや電気抵抗等の特性のバラツキが小さいことが要
求される。In addition to the SD characteristics described above, the basic characteristics are that the battery separator has a low electric resistance value, high mechanical strength such as tensile elastic modulus, and film thickness unevenness and electric resistance. It is required that the variation in the characteristics of is small.

【００１４】また、リチウム電池用セパレータとして用
いられる多孔質フィルムとしては、ＰＰを高ドラフト比
（フィルム成形時におけるフィルムの引取速度をダイか
らの樹脂の押出速度で除した値）でフィルム状に押出成
形し、これを熱処理した後、延伸して得られるＰＰ多孔
質フィルム（特公昭４６−４０１１９号公報、特公昭５
５−３２５３１号公報、米国特許第３６７９５３８号明
細書および米国特許第３８０１４０４号明細書）、特定
の分子量、分子量分布を有するＰＥ、無機微粉体および
有機液状体の三成分を混合してフィルム状に成形した
後、無機微粉体および有機液状体を抽出し、次いで延伸
して得られるＰＥ多孔質フィルム（特公昭５９−３７２
９２号公報）、あるいはＰＰとＰＥから成る二軸配向さ
れた多孔質フィルム（特開昭５０−１１１１７４号公
報）が知られている。As a porous film used as a lithium battery separator, PP is extruded into a film at a high draft ratio (a value obtained by dividing the film take-up speed during film forming by the resin extruding speed from the die). A PP porous film obtained by molding, heat-treating, and stretching (Japanese Patent Publication No. 46-40119 and Japanese Examined Patent Publication 5).
5-32531, U.S. Pat. No. 3,679,538 and U.S. Pat. No. 3,801,404), PE having a specific molecular weight and molecular weight distribution, inorganic fine powder and an organic liquid are mixed to form a film. After molding, a PE porous film obtained by extracting the inorganic fine powder and the organic liquid and then stretching it (Japanese Patent Publication No. 59-372).
92) or a biaxially oriented porous film composed of PP and PE (Japanese Patent Laid-Open No. 50-111174).

【００１５】[0015]

【発明が解決しようとする課題】ところで、本発明者が
行なった実験によれば、上記ＰＰ製多孔質フィルムから
成る電池用セパレータはＳＤ開始温度が１７０℃以上と
高く、一方、ＰＥ製多孔質フィルムから成る電池用セパ
レータはＳＤ開始温度が約１３５℃で適当であるが、耐
熱温度はたかだか１４５℃と低く、いずれも安全性確保
の点で未だ改良すべきものであることが判った。According to an experiment conducted by the present inventor, a battery separator made of the above PP porous film has a high SD onset temperature of 170 ° C. or higher, while a PE porous film is used. A battery separator made of a film is suitable at an SD starting temperature of about 135 ° C., but has a low heat resistance temperature of at most 145 ° C., and it was found that all of them should be improved in terms of ensuring safety.

【００１６】そして、ＰＥ製多孔質フィルムは引張弾性
率が約３２００ｋｇ／ｃｍ2 以下と低く、例えば、これ
をセパレータとして電池内に組み込む際に、伸びを生じ
易いので生産速度を上げられないという問題も有してい
る。また、通常の分子量のＰＥと高分子量ＰＥの混合物
から成る多孔質フィルムは、特性向上が見られるもの
の、耐熱性は約１５０℃、引張弾性率は約３４００ｋｇ
／ｃｍ2 であり、未だ充分でない。The tensile modulus of the PE porous film is as low as about 3200 kg / cm 2 or less, and for example, when it is incorporated into a battery as a separator, it is likely to cause elongation, so that the production rate cannot be increased. I also have. In addition, although a porous film made of a mixture of a normal molecular weight PE and a high molecular weight PE has improved properties, it has a heat resistance of about 150 ° C and a tensile elastic modulus of about 3400 kg.
/ Cm 2, which is not yet sufficient.

【００１７】更に、材質の異なる多孔質フィルムを重ね
合わせたセパレータはＳＤ特性の点では好ましい結果を
得られると思われるが、重ね合わせにより各フィルムの
微孔位置が互いにズレ、この重ね合わせ体においては微
孔が表面から裏面に連通しなくなるため電気抵抗が増加
する。また、重ね合わせに際して接着剤を使用したとき
は、多くの微孔のうちの一部が接着剤により閉塞され、
このことによっても電気抵抗が増加する。更に、当然の
ことながら重ね合わせにより厚さが増加し電池の小型
化、高エネルギー密度化に逆行することとなる。Further, it is considered that a separator obtained by laminating porous films made of different materials can obtain a preferable result in terms of SD characteristics, but the micropore positions of the respective films are displaced from each other due to the superposition, and in this laminated body. The micropores no longer communicate from the front surface to the back surface, increasing the electrical resistance. Also, when an adhesive is used for overlapping, some of the many fine holes are blocked by the adhesive,
This also increases the electrical resistance. Further, as a matter of course, due to the superposition, the thickness increases, which goes against the battery size reduction and high energy density.

【００１８】また、特開昭５０−１１１１７４号公報記
載の多孔質フィルムはＰＰとＰＥの混合物から成る二軸
延伸フィルムであるが、公報中に「このフィルムを室温
にてメタノール中に浸漬したところ、約１分間で透明化
した。」と記載され、通常、電池用セパレータとして用
いられる多孔質フィルムがメタノール中に浸漬すると殆
ど瞬時に透明化するのに比べ長時間要しているところか
ら、多孔化の程度が低く、従って、電池用セパレータと
して使用するには電気抵抗が高過ぎ、実用性に乏しいと
思われる。The porous film described in JP-A-50-111174 is a biaxially stretched film composed of a mixture of PP and PE. In the publication, "When this film is immersed in methanol at room temperature, , It became transparent in about 1 minute. ”Since it takes a long time as compared with the case where a porous film used as a battery separator usually becomes transparent almost instantly when immersed in methanol, The degree of change is low, and therefore, the electric resistance is too high to be used as a battery separator, and it is considered to be poor in practicality.

【００１９】[0019]

【課題を解決するための手段】本発明者は従来技術の有
する問題を解決するため種々研究を行なってきた。即
ち、ＰＥ製多孔質フィルムから成るセパレータの有する
耐熱温度の低さと、機械的強度が不足するという問題
点、ＰＰ製多孔質フィルムから成るセパレータがＳＤ開
始温度が高すぎるという問題点を解決するべく研究を続
けて来た。The present inventor has conducted various studies to solve the problems of the prior art. That is, in order to solve the problems that the separator made of a porous film made of PE has a low heat resistant temperature and the mechanical strength is insufficient, and that the separator made of a porous film made of PP has an SD starting temperature that is too high. I have continued my research.

【００２０】そして、先にＰＥとＰＰの混合物から成る
多孔質電池用セパレータ（特願平２−３３４３０９号）
を提案した。この電池用セパレータはＰＥとＰＰを混合
することおよび新規な製造法の採用により、従来品より
もＳＤ特性の向上したものである。しかし、電気抵抗
値、シワの発生等のような更に改善すべき点もある。Then, a separator for a porous battery, which is composed of a mixture of PE and PP (Japanese Patent Application No. 2-334309).
Proposed. This battery separator has improved SD characteristics as compared with conventional products by mixing PE and PP and adopting a new manufacturing method. However, there are points to be further improved such as electric resistance and wrinkles.

【００２１】本発明者はこのような現状を踏まえ、更
に、研究を続け、ＰＥとして特定の物性値を有するもの
を用いることにより、ＳＤ開始温度、耐熱温度、耐熱温
度幅、電気抵抗、機械的強度のような特性が実用レベル
であり、また、シワ等が無くて外観が良好で、電池用セ
パレータ等として有用な多孔質フィルムが得られること
を見い出し、本発明を完成するに至ったものである。Based on the present situation, the present inventor further continues to study, and by using PE having a specific physical property value, SD start temperature, heat resistant temperature, heat resistant temperature range, electric resistance, mechanical resistance It was found that a characteristic such as strength is at a practical level, the appearance is good without wrinkles, etc., and a porous film useful as a battery separator or the like can be obtained, thus completing the present invention. is there.

【００２２】即ち、本発明に係る多孔質フィルムはＰＰ
とＰＥを必須成分とする組成物から成るものであり、こ
れら両者の合計重量中に占めるＰＰの割合が１０〜９０
％、ＰＥの割合が９０〜１０％であり、そして、該ＰＥ
は高温ゲルパーミエィションクロマトグラフ（以下、
「高温ＧＰＣ」と称す）で測定した重量平均分子量Ｍｗ
と数平均分子量Ｍｎの比Ｍｗ／Ｍｎが１０以下であるこ
とを特徴とするものである。That is, the porous film according to the present invention is PP
And PE as essential components, and the proportion of PP in the total weight of both is 10 to 90.
%, The proportion of PE is 90 to 10%, and the PE
Is a high temperature gel permeation chromatograph (hereinafter,
Weight average molecular weight Mw measured by "high temperature GPC")
And the number average molecular weight Mn ratio Mw / Mn is 10 or less.

【００２３】本発明の多孔質フィルムはＰＰとＰＥを必
須成分とする組成物から成り、これら両者の合計重量中
に占めるＰＰの割合は１０〜９０％（好ましくは４０〜
８０％、更に好ましくは４５〜７５％）、ＰＥの割合は
９０〜１０％（好ましくは６０〜２０％、更に好ましく
は５５〜２５％）である。The porous film of the present invention comprises a composition containing PP and PE as essential components, and the proportion of PP in the total weight of both is 10-90% (preferably 40-).
80%, more preferably 45 to 75%), and the PE ratio is 90 to 10% (preferably 60 to 20%, more preferably 55 to 25%).

【００２４】本発明に係る多孔質フィルムにおいて、Ｐ
ＰとＰＥの重量割合は該フィルムを電池用セパレータと
して用いる場合、そのＳＤ開始温度、耐熱温度および耐
熱温度幅に影響を与える。ＰＰあるいはＰＥの融点等に
よっても変わり得るが、一般に、ＰＰの割合が多くなる
程、耐熱温度は高くなるがＳＤ開始温度も高くなり、Ｐ
Ｐが少なくなる程、耐熱温度は低くなる。In the porous film according to the present invention, P
When the film is used as a battery separator, the weight ratio of P and PE affects the SD start temperature, heat resistant temperature and heat resistant temperature range. Although it may vary depending on the melting point of PP or PE, generally, the higher the proportion of PP, the higher the heat-resistant temperature but the higher the SD onset temperature.
The lower the P content, the lower the heat resistant temperature.

【００２５】本発明においては、このようにフィルム形
成材料であるＰＰとＰＥの割合を上記特定範囲とする必
要がある。ＰＰの重量割合が９０％よりも多いときは、
ＳＤ開始温度が高くなり過ぎるばかりでなく所定温度で
の電気抵抗値の増大作用が不充分となり、ＰＰの割合が
１０％よりも少ないときは、耐熱温度が低くなると共に
耐熱温度幅が狭くなり、いずれも実用性に劣るので好ま
しくない。In the present invention, it is necessary that the ratio of PP and PE which are the film forming materials is within the above specified range. When the weight ratio of PP is more than 90%,
Not only the SD start temperature becomes too high, but the effect of increasing the electric resistance value at a predetermined temperature becomes insufficient, and when the proportion of PP is less than 10%, the heat resistant temperature becomes low and the heat resistant temperature range becomes narrow, Both are unpractical and are not preferred.

【００２６】本発明に係る多孔質フィルムを構成する材
料であるＰＥとしては、高密度ＰＥ、中密度ＰＥ、低密
度ＰＥ、線状低密度ＰＥの他、エチレンとビニル化合物
との共重合体も使用できる。ビニル化合物としては例え
ば、酢酸ビニル、アクリル酸メチル、メタクリル酸メチ
ル、塩化ビニル、スチレン等が挙げられる。これらのな
かでも特に結晶性の高い高密度ＰＥが好ましいが、ＰＰ
とＰＥの合計重量中に占めるＰＥの割合が５０％以下の
場合には中密度ＰＥ、低密度ＰＥ、線状低密度ＰＥおよ
びエチレンとビニル化合物の共重合体等の結晶性の低い
樹脂も使用できる。Examples of PE which is a material constituting the porous film according to the present invention include high density PE, medium density PE, low density PE, linear low density PE, and a copolymer of ethylene and a vinyl compound. Can be used. Examples of the vinyl compound include vinyl acetate, methyl acrylate, methyl methacrylate, vinyl chloride and styrene. Among these, high-density PE having particularly high crystallinity is preferable, but PP
When the proportion of PE in the total weight of PE and PE is 50% or less, low crystallinity resins such as medium density PE, low density PE, linear low density PE and copolymers of ethylene and vinyl compounds are also used. it can.

【００２７】そして、これらＰＥとしては高温ＧＰＣで
測定した重量平均分子量Ｍｗと数平均分子量Ｍｎの比Ｍ
ｗ／Ｍｎが１０以下のものを用いることが重要である。
Ｍｗ／Ｍｎが１０よりも大きな場合には、成形時に厚さ
ムラの少ないフィルムを得るのが困難であるばかりでな
く、延伸時にフィルムが裂け易い等の欠点を生ずるので
好ましくない。As for these PEs, the ratio M of the weight average molecular weight Mw and the number average molecular weight Mn measured by high temperature GPC is M.
It is important to use those with w / Mn of 10 or less.
When Mw / Mn is larger than 10, it is not preferable because it is difficult to obtain a film having a small thickness unevenness at the time of molding, and the film is easily torn during stretching.

【００２８】また、ＰＰとしては立体規則性の高いＰＰ
を用いることが特に好ましい。勿論、ＰＰの割合が低い
場合、例えば、ＰＰとＰＥの合計重量中に占めるＰＰの
割合が５０％未満であるような場合には、ＰＰ成分とし
てエチレンとの共重合体や立体規則性の低いアタクチッ
ク構造を多く含有するＰＰを使用しても同様に好ましい
結果を得ることができる。Further, PP having high stereoregularity is used as PP.
Is particularly preferably used. Of course, when the proportion of PP is low, for example, when the proportion of PP in the total weight of PP and PE is less than 50%, a copolymer with ethylene as a PP component or a stereoregularity is low. The same favorable result can be obtained by using PP containing a large amount of atactic structure.

【００２９】本発明に係る多孔質フィルムは上記したよ
うにＰＰとＰＥを必須成分とするものであるが、所望に
より、界面活性剤、老化防止剤、可塑剤、難燃剤、着色
剤、ＰＰとＰＥとの相溶性を高めるための相溶化剤等の
添加剤を適量含有していてもよい。また、アクリル酸、
アクリル酸メチル、メタクリル酸、メタクリル酸メチ
ル、酢酸ビニル等の極性モノマーをグラフト共重合させ
る方法、界面活性剤を含浸させる方法等により親水化処
理して用いるようにしてもよい。The porous film according to the present invention contains PP and PE as essential components as described above, but if desired, a surfactant, an antiaging agent, a plasticizer, a flame retardant, a colorant and PP may be added. An appropriate amount of an additive such as a compatibilizing agent for increasing compatibility with PE may be contained. Also, acrylic acid,
You may make it hydrophilic by the method of graft-copolymerizing polar monomers, such as methyl acrylate, methacrylic acid, methyl methacrylate, and vinyl acetate, and the method of impregnating a surfactant.

【００３０】上記界面活性剤の具体例として、例えば、
高級脂肪酸アルカリ塩、アルキル硫酸塩、アルキルスル
ホン酸塩、アルキルアリールスルホン酸塩、スルホコハ
ク酸エステル塩等の陰イオン界面活性剤、高級アミンハ
ロゲン酸塩、ハロゲン化アルキルピリジニウム、第四ア
ンモニウム塩等の陽イオン界面活性剤、ポリエチレング
リコールアルキルエーテル、ポリエチレングリコール脂
肪酸エステル、ソルビタン脂肪酸エステル、脂肪酸モノ
グリセリド等の非イオン界面活性剤を挙げることができ
る。Specific examples of the above surfactant include, for example,
Anionic surfactants such as higher fatty acid alkali salts, alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, sulfosuccinic acid ester salts, etc., higher amine halogenates, alkylpyridinium halides, quaternary ammonium salts etc. Nonionic surfactants such as ionic surfactants, polyethylene glycol alkyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, and fatty acid monoglycerides can be mentioned.

【００３１】本発明に係る多孔質フィルムは電池用セパ
レータとして好適に使用でき、このセパレータは多孔質
構造を有する点では、前記従来のＰＥ多孔質フィルムあ
るいはＰＰ多孔質フィルムから成るセパレータと共通す
るが、ＳＤ機能の発揮機構がこれらとは異なるものであ
る。The porous film according to the present invention can be suitably used as a battery separator, and this separator has a porous structure in common with the conventional separator made of PE porous film or PP porous film. , SD function display mechanism is different from these.

【００３２】前記従来のセパレータではＰＥまたはＰＰ
の軟化点乃至融点に達すると溶融現象により多孔質構造
から無孔構造に変化し、電気抵抗値の増大が生じて電流
が遮断されるのである。従って、そのＳＤ特性はセパレ
ータを構成するＰＥまたはＰＰの軟化点乃至融点に依存
することになる。それ故に、ＰＥ多孔質フィルム製のセ
パレータは耐熱温度が低く、一方、ＰＰ多孔質フィルム
製のセパレータはＳＤ開始温度が高過ぎて安全性の確保
に不安があったのである。また、これらいずれのセパレ
ータもＳＤ開始温度と耐熱温度が接近していて耐熱温度
幅が狭く、この点からも安全性に懸念があったのであ
る。In the conventional separator, PE or PP is used.
When it reaches the softening point or melting point, the structure changes from a porous structure to a non-porous structure due to the melting phenomenon, the electric resistance value increases, and the current is cut off. Therefore, the SD characteristic depends on the softening point or melting point of PE or PP constituting the separator. Therefore, the separator made of PE porous film has a low heat resistance temperature, while the separator made of PP porous film has an excessively high SD starting temperature, and there was a concern about ensuring safety. Further, in all of these separators, the SD starting temperature and the heat-resistant temperature are close to each other, and the heat-resistant temperature range is narrow.

【００３３】ところが、本発明に係るＰＰと特定の物性
値を有するＰＥを必須成分とする組成物から成る多孔質
フィルムをセパレータとした場合には、温度が上昇して
ＰＥの軟化点乃至融点に達するとセパレータを構成する
ＰＥ部分が軟化乃至溶融することにより、ＰＥ部分が多
孔質である場合はその部分が多孔質構造を喪失して抵抗
値を増大させる他、ＰＰ部分が多孔質構造である場合に
はそのＰＰ部分の多孔質構造も閉塞させて、その結果、
抵抗値が増大して電流が遮断され、温度の過昇が防止さ
れる。そして、ＰＰの融点に至るまでは該ＰＰによりフ
ィルム形状が維持されるので、充分な耐熱温度を示すの
である。However, when a porous film composed of PP according to the present invention and a composition containing PE having a specific physical property value as an essential component is used as a separator, the temperature rises to reach the softening point or melting point of PE. When it reaches, the PE portion constituting the separator is softened or melted, and when the PE portion is porous, the portion loses the porous structure to increase the resistance value, and the PP portion has the porous structure. In some cases, the porous structure of the PP part is also blocked, and as a result,
The resistance value increases, the current is cut off, and the temperature rise is prevented. Since the film shape is maintained by the PP until the melting point of PP is reached, a sufficient heat resistant temperature is exhibited.

【００３４】即ち、本発明に係る多孔質フィルムをセパ
レータとした場合には、それを構成するＰＥが主として
ＳＤ開始温度および抵抗値の増大に寄与し、ＰＰが主と
して耐熱温度に寄与することにより、安全性に富むセパ
レータが提供できるのである。このように、二つの構成
材料が異なる機能を分担することにより、優れた実用性
を発揮するようにした点は、従来品と全く異なるもので
ある。That is, when the porous film according to the present invention is used as a separator, PE constituting the separator mainly contributes to the increase of the SD start temperature and the resistance value, and PP mainly contributes to the heat resistance temperature. A highly safe separator can be provided. In this way, the two constituent materials have different functions from each other, and thus the excellent practicality is exhibited, which is completely different from the conventional product.

【００３５】かような本発明に係る多孔質フィルムを電
池用セパレータとして用いる場合には従来のセパレータ
と同様に、正極と負極の間に介在せしめて電池を組み立
てることができる。この際、正極、負極、電池ケース、
電解液等の材質やこれら構成要素の配置構造は何ら格別
である必要はなく、従来の電池と同様であってよいので
ある。When such a porous film according to the present invention is used as a battery separator, the battery can be assembled by interposing it between the positive electrode and the negative electrode as in a conventional separator. At this time, the positive electrode, the negative electrode, the battery case,
The material of the electrolytic solution or the like and the arrangement structure of these constituent elements do not have to be special and may be the same as those of the conventional battery.

【００３６】次に、本発明に係る多孔質フィルムの製法
について説明する。この製法も本発明者が開発した新規
な方法であり、ＰＰ（この融点をＴｍａ℃とする）とＰ
Ｅ（この融点をＴｍｂ℃とする）を必須成分とする組成
物をフィルム成形し、このフィルムをＴｍｂ℃〜（Ｔｍ
ａ＋１０）℃の温度で熱処理し、次いで−２０℃〜６０
℃の温度で延伸して多孔質化することを特徴とする方法
である。Next, the method for producing the porous film according to the present invention will be described. This manufacturing method is also a novel method developed by the present inventor, and PP (this melting point is Tma ° C.) and P
A composition containing E (this melting point as Tmb ° C) as an essential component is formed into a film, and the film is formed at Tmb ° C to (Tm ° C).
a + 10) ° C., then heat treated at −20 ° C. to 60 ° C.
The method is characterized in that it is made porous by stretching at a temperature of ° C.

【００３７】この方法においては、先ず、ＰＰとＰＥを
必須成分とする組成物がフィルム成形される。この成形
に際しては従来から熱可塑性樹脂のフィルム成形法とし
て知られているＴダイ式押出法、インフレーション法等
を採用できる。成形条件、例えば、ドラフト比（ｄｒａ
ｗ ｒａｔｉｏまたはｄｒｏｗｄｏｗｎ ｒａｔｉｏと
もいう）は通常２０以上好ましくは５０以上に、フィル
ムの引取速度は通常５ｍ／ｍｉｎ〜２００ｍ／ｍｉｎ好
ましくは１０ｍ／ｍｉｎ〜１００ｍ／ｍｉｎに設定でき
るが、これらは限定されるものではない。このフィルム
引取速度とドラフト比とは相関関係を有し、フィルム引
取速度が大きい場合はドラフト比は小さくでき、引取速
度が小さい場合はドラフト比を比較的大きくすることが
できる。なお、上記ドラフト比とはフィルムの引取速度
Ｖ2 をダイスから押し出される樹脂の線速度（Ｖ1 ）で
除した値である。即ち、ドラフト比（Ｄ）は下記数１で
表されるものである。In this method, first, a composition containing PP and PE as essential components is formed into a film. In this molding, a T-die type extrusion method, an inflation method or the like which has heretofore been known as a thermoplastic resin film molding method can be adopted. Molding conditions such as draft ratio (dra
w ratio or drawdown ratio) is usually 20 or more, preferably 50 or more, and the film take-off speed is usually 5 m / min to 200 m / min, preferably 10 m / min to 100 m / min, but these are not limited. Not a thing. There is a correlation between the film take-up speed and the draft ratio. When the film take-up speed is high, the draft ratio can be made small, and when the film take-up speed is small, the draft ratio can be made relatively large. The draft ratio is a value obtained by dividing the film take-up speed V 2 by the linear speed (V 1 ) of the resin extruded from the die. That is, the draft ratio (D) is expressed by the following formula 1.

【００３８】[0038]

【数１】 [Equation 1]

【００３９】ここに用いるフィルム状物は、ＰＰとＰＥ
を必須成分とし、更に所望により添加剤を適量配合した
組成物を二軸押出機、ニーダー、ロール、バンバリーミ
キサー等により溶融混練し、次いでＴダイ押出成形、イ
ンフレーション成形等により溶融成形して得られる。The film material used here is made of PP and PE.
Is obtained by melt-kneading a composition containing, as an essential component and, if desired, an additive in an appropriate amount by a twin-screw extruder, a kneader, a roll, a Banbury mixer, and then T-die extrusion molding, inflation molding, etc. .

【００４０】このフィルム状物を得る際には、ＰＥとＰ
Ｐ両者の合計重量中に占めるＰＰの割合が１０〜９０％
好ましくは４０〜８０％になるように配合する。そし
て、ＰＥとして高温ＧＰＣで測定した重量平均分子量Ｍ
ｗと数平均分子量Ｍｎの比Ｍｗ／Ｍｎが１０以下のもの
を用いることが好ましい。To obtain this film-like product, PE and P
The proportion of PP in the total weight of both P is 10 to 90%
It is preferably blended so as to be 40 to 80%. And the weight average molecular weight M measured by high temperature GPC as PE
It is preferable to use one having a ratio Mw / Mn of w to the number average molecular weight Mn of 10 or less.

【００４１】本発明に係る方法において、フィルム状物
の成形に際して、ドラフト比は上記した如く限定されな
いが、フィルム成形性の観点から通常約５００以下とす
るのがよい。しかし、所望によりこれよりも高いドラフ
ト比とすることもできる。また、本発明者はドラフト比
が低くなるにつれ、得られる多孔質フィルムの電気抵抗
値が高くなること、およびドラフト比が約２０以上であ
れば、得られる多孔質フィルムの電気抵抗値はほぼ実用
性を有するものであることを確認している。これらを考
慮し、本発明の方法の実施に際し、ドラフト比は通常約
２０〜５００の範囲に設定される。In the method according to the present invention, when forming a film-like material, the draft ratio is not limited as described above, but from the viewpoint of film formability, it is usually about 500 or less. However, higher draft ratios can be used if desired. Further, the present inventors have found that the electric resistance value of the obtained porous film becomes higher as the draft ratio becomes lower, and if the draft ratio is about 20 or more, the electric resistance value of the obtained porous film is practically practical. It has been confirmed that it has sex. In consideration of these, when carrying out the method of the present invention, the draft ratio is usually set in the range of about 20 to 500.

【００４２】結晶性高分子は高ドラフト比で成形するこ
とによりラメラ（ｌａｍｅｌｌａ、板状結晶）がフィル
ムの引取方向に対して垂直方向に列をなして並んだ構造
（ｒｏｗ ｓｔｒｕｃｔｕｒｅ）をとることが知られて
いる（例えば、Ｈ．Ｓ．Ｂｉｅｒｅｎｂａｕｍら，Ｉｎ
ｄ．Ｅｎｇ．Ｃｈｅｍ．，Ｐｒｏｄ．Ｒｅｓ．Ｄｅｖｅ
ｌｏｐ．ｖｏｌ．１３，Ｎｏ．１，Ｐ．２，１９７
４）。そして、上記方法で成形されたフィルム状物も同
様な構造を有していることが確認されている。The crystalline polymer may be molded at a high draft ratio to have a structure in which lamellas (plate crystals) are arranged in a line in a direction perpendicular to the film take-up direction. Known (eg, HS Bierenbaum et al., In
d. Eng. Chem. , Prod. Res. Dev
lop. vol. 13, No. 1, P. 2,197
4). It has been confirmed that the film-like material formed by the above method also has a similar structure.

【００４３】本発明の方法においては、このフィルム状
物が次いで熱処理（ａｎｎｅａｌｉｎｇ、以下、「アニ
ーリング」と称す）される。このアニーリングを施すこ
とにより後に行なわれる延伸工程での微細孔の形成が促
進され、高気孔率の多孔質フィルムを得ることができる
のである。In the method of the present invention, this film-like material is then heat-treated (annealing, hereinafter referred to as "annealing"). By performing this annealing, the formation of fine pores in the stretching step performed later is promoted, and a porous film having a high porosity can be obtained.

【００４４】アニーリングの方法は任意であってよく、
例えば、加熱されたロールや金属板にフィルム状物を接
触させる方法、フィルム状物を空気中や不活性ガス中で
加熱する方法、フィルム状物を芯体上にロール状に巻取
り、これを気相中で加熱する方法等を採用できる。な
お、フィルム状物を芯体上に巻取り、これを気相中で加
熱する場合には、ブロッキング防止のため、フィルム状
物に離型性シートを重ね合わせて巻き取ることができ
る。かような離型性シートとしては、ポリエチレンテレ
フタレートフィルム、フッ素樹脂フィルムのような耐熱
性フィルム、紙やプラスチックフィルムにシリコーン樹
脂等の離型剤を塗布したもの等を用いることができる。The method of annealing may be arbitrary,
For example, a method of bringing a film-like material into contact with a heated roll or a metal plate, a method of heating the film-like material in air or an inert gas, and winding the film-like material on a core body in a roll shape, A method of heating in a gas phase or the like can be adopted. When the film-like material is wound on a core and heated in a gas phase, a release sheet can be superposed on the film-like material and wound up to prevent blocking. As such a release sheet, a polyethylene terephthalate film, a heat resistant film such as a fluororesin film, or a paper or plastic film coated with a release agent such as a silicone resin can be used.

【００４５】アニーリング温度はＴｍｂ℃〜（Ｔｍａ＋
１０）℃に設定する。この温度でのアニーリングは上記
したような種々の方法により行うことができるが、アニ
ーリングの方法により、好適な温度範囲が存在する。例
えば、加熱されたロールや金属板にフィルム状物を接触
させる方法ではＴｍｂ℃〜（Ｔｍａ−５）℃が、フィル
ム状物を空気中や不活性ガス中で加熱する方法ではＴｍ
ｂ℃〜（Ｔｍａ＋５）℃が、フィルム状物を離型性シー
トと重ね合わせて芯体上に巻取り、これを空気中で加熱
する方法ではＴｍｂ℃〜（Ｔｍａ＋１０）℃が、各々好
適な温度範囲である。The annealing temperature is from Tmb ° C to (Tma +
10) Set to ° C. Annealing at this temperature can be performed by various methods as described above, but there is a suitable temperature range depending on the annealing method. For example, Tmb ° C to (Tma-5) ° C in the method of bringing the film-like material into contact with a heated roll or metal plate, and Tm in the method of heating the film-like material in the air or an inert gas.
bC to (Tma + 5) ° C is a method in which a film-like material is superposed on a releasable sheet and wound on a core, and this is heated in air, Tmb ° C to (Tma + 10) ° C is a suitable temperature. It is a range.

【００４６】このアニーリングは、フィルム状物成形時
に生じたラメラのｒｏｗ ｓｔｒｕｃｔｕｒｅを更に成
長させ、後に行われる延伸による微細孔形成を促進させ
るためのものである。従って、ＰＥとＰＰという融点の
異なる樹脂混合物から成るフィルム状物の結晶構造（ラ
メラのｒｏｗ ｓｔｒｕｃｔｕｒｅ）をアニーリングに
より更に成長させるには、その温度は当然ＰＥの融点よ
りも低く設定することになると予想された。This annealing is for further growing the row structure of the lamella formed at the time of forming the film-like material, and for promoting the formation of fine pores by the subsequent stretching. Therefore, in order to further grow the crystal structure (lamellar row structure) of a film mixture composed of a resin mixture of PE and PP having different melting points, it is expected that the temperature will naturally be set lower than the melting point of PE. Was done.

【００４７】しかしながら、本発明の方法においては、
驚くべきことに上記領域の温度、即ち、ＰＥの融点以上
の高温に設定する必要があることが判明した。アニーリ
ング温度が低過ぎる場合はラメラの成長が充分でなく、
得られる多孔質フィルムの電気抵抗値が高くなり、ま
た、アニーリング温度が高過ぎる場合には結晶構造が喪
失するばかりでなく、相分離構造が粗大化して、フィル
ム状物が脆くなり、延伸し難くなるので、いずれも好ま
しくない。However, in the method of the present invention,
Surprisingly, it has been found that it is necessary to set the temperature in the above-mentioned region, that is, the high temperature above the melting point of PE. If the annealing temperature is too low, the lamella will not grow sufficiently,
The electric resistance value of the obtained porous film becomes high, and not only the crystal structure is lost when the annealing temperature is too high, but also the phase separation structure becomes coarse, and the film-like material becomes brittle, and it is difficult to stretch. Therefore, both are not preferable.

【００４８】なお、アニーリングに要する時間はフィル
ム状物中におけるＰＥとＰＰの割合、アニーリング温度
等に応じて設定するが、通常、約２秒〜５０時間、好ま
しくは１０秒〜２０時間である。The time required for annealing is set according to the ratio of PE to PP in the film-like material, the annealing temperature, etc., but is usually about 2 seconds to 50 hours, preferably 10 seconds to 20 hours.

【００４９】このようにしてアニーリングした後、これ
を延伸する。延伸方法は従来から知られているロール式
延伸、テンター式延伸等により行うことができる。After annealing in this way, it is stretched. The stretching method can be performed by conventionally known roll stretching, tenter stretching, or the like.

【００５０】延伸は−２０℃〜６０℃（以下、−２０℃
〜６０℃での延伸を「低温延伸」と称す）で行なう。延
伸温度が低過ぎると作業中にフィルムの破断を生じ易
く、高過ぎると多孔質化し難い。延伸の作業性の点から
温度を−２０〜５５℃とするのが好ましいことが判明し
ている。The stretching is from -20 ° C to 60 ° C (hereinafter, -20 ° C).
Stretching at -60 ° C is referred to as "cold stretching"). If the stretching temperature is too low, the film is likely to break during the work, and if it is too high, it is difficult to make it porous. It has been found that it is preferable to set the temperature at -20 to 55 ° C from the viewpoint of workability of stretching.

【００５１】そして、このときの延伸率は限定されるも
のではないが、通常２０〜４００％好ましくは５０〜３
００％とされる。なお、この延伸率（Ｍ1 ％）は下記数
２によって表される。数２中におけるＬ0 は低温延伸前
の寸法、Ｌ1 は低温延伸後の寸法である。The stretching ratio at this time is not limited, but is usually 20 to 400%, preferably 50 to 3%.
It is set to 00%. The stretching ratio (M 1 %) is represented by the following mathematical expression 2. In Formula 2, L 0 is the dimension before the low temperature stretching, and L 1 is the dimension after the low temperature stretching.

【００５２】[0052]

【数２】 [Equation 2]

【００５３】上記方法によって得られる多孔質フィルム
のミクロ構造は特異なものであり、その構造は電子顕微
鏡により観察できる。なお、観察に際しては多孔質フィ
ルムをルテニウム酸水溶液の蒸気に接触させて染色して
おくのがよい。The microstructure of the porous film obtained by the above method is unique, and the structure can be observed by an electron microscope. At the time of observation, it is preferable that the porous film is contacted with the vapor of the ruthenic acid aqueous solution and dyed.

【００５４】先ず、走査型電子顕微鏡（Ｓｃａｎｎｉｎ
ｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ、以下、
「ＳＥＭ」と称す）により倍率約１０００〜３００００
倍でその表面を観察する。First, a scanning electron microscope (Scannin)
g Electron Microscope, below,
Approximately 1000 to 30,000 by "SEM")
Observe the surface at double.

【００５５】そして、更に、多孔質フィルムをその成形
時における引取方向に対して直交する方向あるいは該引
取方向と平行な方向に沿って切断し、これら２つの切断
面を透過型電子顕微鏡（Ｔｒａｎｓｍｉｓｓｉｎ Ｅｌ
ｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ、以下、「ＴＥ
Ｍ」と称す）により倍率約５０００〜１０万倍で観察す
る。Further, the porous film is further cut along a direction orthogonal to the take-up direction at the time of molding or a direction parallel to the take-up direction, and these two cut surfaces are cut by a transmission electron microscope (Transmissin El).
electron Microscope, hereafter "TE
It is observed at a magnification of about 5000 to 100,000 times.

【００５６】これら表面および両断面の観察により、こ
の多孔質フィルムにおいてはＰＰ部分とＰＥ部分が互い
に独立して存在する相分離構造を有し、ＰＰ部分または
ＰＥ部分の一方が連続相、他方が非連続相（分散相とも
いう）として存在し、少なくとも連続相をなす樹脂部分
が多孔質となっているのが判る。By observing these surfaces and both cross sections, the porous film has a phase-separated structure in which the PP portion and the PE portion exist independently of each other, and one of the PP portion and the PE portion has a continuous phase and the other has It can be seen that the resin portion that exists as a discontinuous phase (also referred to as a dispersed phase) and that forms at least the continuous phase is porous.

【００５７】このような本発明に係る多孔質フィルムの
ミクロ構造は、従来から知られている単一成分から成る
多孔質フィルム、同種のポリマーの混合物から成る多孔
質フィルム等のそれとは全く異なる新規なものである。The microstructure of the porous film according to the present invention as described above is completely different from that of the conventionally known porous film composed of a single component, porous film composed of a mixture of polymers of the same kind, and the like. It is something.

【００５８】本発明に係る多孔質フィルムのミクロ構造
を電子顕微鏡で観察した結果について、更に詳細に述べ
る。ＳＥＭによる表面観察では、多孔質部分はフィルム
成形時の引取方向とほぼ直交する方向に配列した多数の
ラメラ（結晶）と該引取方向にほぼ平行で且つ隣接する
ラメラ相互を連結する多数の微細な繊維（フィブリル）
が存在し、繊維と繊維との間が微細な気孔となった構造
を有していることが判る。The results of observing the microstructure of the porous film according to the present invention with an electron microscope will be described in more detail. In the surface observation by SEM, the porous portion has a large number of lamellas (crystals) arranged in a direction substantially orthogonal to the take-up direction at the time of film formation and a large number of fine lamellas that are parallel to the take-up direction and connect adjacent lamellas. Fiber
Is present, and it has a structure in which fine pores are formed between the fibers.

【００５９】そして、気孔やラメラの形状の差異によっ
てＰＥ部分とＰＰ部分を識別することができる。例え
ば、ＰＰ部分とＰＥ部分の両者が多孔質構造である場
合、両部分の多孔質構造を比べると、通常、ＰＥ部分は
ＰＰ部分に比べその孔径が大きく、また、ＰＰ部分のラ
メラの形状が規則的であるのにＰＥ部分のそれは不規則
的である。従って、上記したように多孔質フィルム表面
におけるＰＥ部分とＰＰ部分とを判別できるのである。Then, the PE portion and the PP portion can be distinguished from each other by the difference in the shape of the pores and the lamella. For example, when both the PP portion and the PE portion have a porous structure, comparing the porous structures of both portions, the PE portion usually has a larger pore diameter than the PP portion, and the PP portion has a lamella shape. While regular, that of the PE part is irregular. Therefore, the PE portion and the PP portion on the surface of the porous film can be discriminated as described above.

【００６０】一方、ＴＥＭによる両断面の観察ではＰＥ
部分がＰＰ部分より染色され易くて黒く見えるので、両
部分の判別は表面観察のときよりも容易である。そし
て、主として成形時における引取方向に平行な方向に切
断した断面の観察により、少なくとも連続相が多孔質で
あること、および非連続相が多孔質か非多孔質かが判
る。また、この引取方向に平行な方向に切断した断面
は、連続相を成形する樹脂部分のラメラの配列や微細孔
の観察にも適している。On the other hand, when observing both cross sections by TEM, PE
Since the part is easier to be dyed than the PP part and looks black, it is easier to distinguish both parts from the surface observation. Then, by observing the cross section cut mainly in the direction parallel to the take-up direction during molding, it can be seen that at least the continuous phase is porous and whether the discontinuous phase is porous or non-porous. The cross section cut in the direction parallel to the take-up direction is also suitable for observing the lamella arrangement and fine pores of the resin portion forming the continuous phase.

【００６１】本発明に係る多孔質フィルムにおいて、好
ましい相分離構造は、ＰＰ部分が連続相として存在し、
ＰＥ部分が非連続相として存在する場合である。この態
様のときに、最も好ましいＳＤ開始温度と高い耐熱温度
を示すことが確認されている。この態様の場合には、当
然のことながら連続相としてのＰＰ部分が多孔質構造を
有している。そして、非連続相としてのＰＥ部分は多孔
質あるいは非多孔質のいずれであってもよいが、多孔質
構造であれば電気抵抗がより小さくなるので好ましい。In the porous film according to the present invention, the preferred phase separation structure is that the PP portion is present as a continuous phase,
This is the case when the PE portion is present as a discontinuous phase. It has been confirmed that the most preferable SD onset temperature and high heat resistant temperature are exhibited in this embodiment. In the case of this embodiment, the PP portion as the continuous phase naturally has a porous structure. The PE portion as the discontinuous phase may be either porous or non-porous, but a porous structure is preferable because electrical resistance becomes smaller.

【００６２】本発明に係る多孔質フィルムは上記以外の
相分離構造であってもよい。即ち、ＰＰ部分とＰＥ部分
が互いに独立して存在しておれば、ＰＥ部分が多孔質の
連続相、ＰＰ部分が非連続相（この非連続相は多孔質あ
るいは非多孔質のいずれであってもよい）であってもよ
い。The porous film according to the present invention may have a phase separation structure other than the above. That is, if the PP portion and the PE portion exist independently of each other, the PE portion is a porous continuous phase, and the PP portion is a discontinuous phase (this discontinuous phase may be porous or non-porous). May be).

【００６３】上記方法により得られる多孔質フィルムの
ミクロ構造は、主として用いるＰＥ、ＰＰの混合割合と
溶融粘度により決定される。混合割合の多い樹脂が連続
相を形成し易く、また、溶融粘度の低い樹脂が連続相を
形成し易い。The microstructure of the porous film obtained by the above method is determined mainly by the mixing ratio of PE and PP used and the melt viscosity. A resin having a large mixing ratio easily forms a continuous phase, and a resin having a low melt viscosity easily forms a continuous phase.

【００６４】従って、ＰＰとＰＥとの混合割合を変えた
り、溶融粘度の異なるＰＰとＰＥとを適宜組み合わせた
りすることにより、多孔質フィルムのミクロ構造をコン
トロールできる。例えば、ＰＰとＰＥ両者の合計重量中
に占めるＰＰの割合が多い場合、ＰＰにより多孔質の連
続相が形成され、ＰＥにより非連続相が形成され易い。
そして、このとき、ＰＥとして中密度品または低密度品
を用いると、該ＰＥによる非連続相は非多孔質となり、
高密度品（高結晶化度品）を用いると多孔質構造とな
る。Therefore, the microstructure of the porous film can be controlled by changing the mixing ratio of PP and PE or appropriately combining PP and PE having different melt viscosities. For example, when the proportion of PP in the total weight of both PP and PE is high, PP forms a porous continuous phase and PE easily forms a discontinuous phase.
Then, at this time, when a medium density product or a low density product is used as PE, the discontinuous phase due to the PE becomes non-porous,
When a high density product (high crystallinity product) is used, a porous structure is obtained.

【００６５】なお、本発明に係る多孔質フィルムは少な
くとも一方向の引張弾性率が３５００ｋｇ／ｃｍ2 以上
と大きく、セパレータとして電池内に組み込む際に伸び
を生じ難いので、電池組立速度を上げることができ、ま
た、電池の不良品発生の低減の点でも好ましいものであ
る。The porous film according to the present invention has a large tensile modulus of elasticity in at least one direction of 3500 kg / cm 2 or more, and it is difficult for the porous film to expand when incorporated into a battery as a separator. Therefore, the battery assembling speed can be increased. This is also preferable from the viewpoint of reducing the occurrence of defective batteries.

【００６６】図１は本発明に係る多孔質フィルムのミク
ロ構造の実例を模式的に示している。この例は本発明に
おける最も好ましい態様を示したものである。図１にお
いて、矢印Ｘは多孔質フィルムの厚さ方向、矢印Ｙは多
孔質フィルムを得る際のフィルム成形時における引取方
向を、矢印Ｚは多孔質フィルムを得る際のフィルム成形
時における引取方向に直交する方向を各々示している。
また、Ａは多孔質フィルムの表面を、Ｂは多孔質フィル
ムの引取方向Ｙに直交する方向に切断した断面、Ｃは引
取方向Ｙに沿って切断した断面を各々示している。FIG. 1 schematically shows an example of the microstructure of the porous film according to the present invention. This example shows the most preferred embodiment of the present invention. In FIG. 1, an arrow X indicates a thickness direction of a porous film, an arrow Y indicates a take-up direction at the time of film formation when obtaining a porous film, and an arrow Z indicates a take-up direction at the time of film formation when obtaining a porous film. The directions orthogonal to each other are shown.
Further, A is the surface of the porous film, B is a cross section cut in a direction orthogonal to the take-up direction Y of the porous film, and C is a cross section taken along the take-up direction Y, respectively.

【００６７】該多孔質フィルムの表面Ａ、断面Ｂおよび
断面Ｃにおいては、いずれもＰＰ部分１と、ＰＥ部分２
が互いに独立して存在する相分離構造を有し、ＰＰ部分
が連続相を、ＰＥ部分が非連続相を形成している。そし
て、これらＰＰ部分１およびＰＥ部分２のいずれも多孔
質である。このように、連続相中に非連続相が点在する
ミクロ構造はいわゆる「海島構造」ということもでき
る。On the surface A, the section B and the section C of the porous film, the PP portion 1 and the PE portion 2 were all formed.
Have a phase-separated structure that exists independently of each other, and the PP portion forms a continuous phase and the PE portion forms a discontinuous phase. Then, both the PP portion 1 and the PE portion 2 are porous. As described above, the microstructure in which the discontinuous phase is scattered in the continuous phase can be referred to as a so-called “sea-island structure”.

【００６８】図１中における３および４は、表面Ａにお
けるＰＰ部分１およびＰＥ部分２に存在する微細孔を各
々示している。なお、断面ＢおよびＣにおけるＰＰ部分
１およびＰＥ部分２にも同様な微細孔が存在するが、図
示は省略してある。Reference numerals 3 and 4 in FIG. 1 indicate fine pores existing in the PP portion 1 and the PE portion 2 on the surface A, respectively. It should be noted that similar micropores are present in the PP portion 1 and the PE portion 2 in the cross sections B and C, but they are not shown.

【００６９】ＰＥ部分２は引取方向Ｙに沿う細長い帯状
または棒状あるいは紐状の薄層として存在することが多
い。ＰＥ部分２の形状は主として、多孔質フィルムを構
成するＰＥの含有量に依存し、ＰＥ含有量が多くなるに
つれて広幅の帯状となり、ＰＥ含有量が少なくなるにつ
れ狭幅の棒状または紐状となる。The PE portion 2 often exists as an elongated strip-shaped or rod-shaped or string-shaped thin layer along the take-up direction Y. The shape of the PE portion 2 mainly depends on the content of PE constituting the porous film, and becomes a wide band shape as the PE content increases, and becomes a narrow rod shape or a string shape as the PE content decreases. .

【００７０】このＰＥ部分２の長さ（Ｙ方向の寸法）は
表面Ａあるいは断面Ｃの観察により知ることができ、通
常、約０．１〜数十μｍである。また、その幅（Ｚ方向
の寸法）は表面Ａあるいは断面Ｂの観察により知ること
ができ、通常、約０．２〜５μｍである。更に、その厚
さ（Ｘ方向の寸法）は断面ＢあるいはＣの観察により知
ることができ、通常、約０．１〜２μｍである。The length (dimension in the Y direction) of the PE portion 2 can be known by observing the surface A or the cross section C, and is usually about 0.1 to several tens of μm. The width (dimension in the Z direction) can be known by observing the surface A or the cross section B, and is usually about 0.2 to 5 μm. Further, the thickness (dimension in the X direction) can be known by observing the cross section B or C, and is usually about 0.1 to 2 μm.

【００７１】また、ＰＰ部分１およびＰＥ部分２におけ
る微細孔３および４は、いずれもその形状が長楕円形も
しくは矩形である。そして、ＰＰ部分１における微細孔
３の寸法は、長径が約０．０５〜０．３μｍ、短径が約
０．０１〜０．１μｍであり、ＰＥ部分２における微細
孔４の寸法は、長径が約０．１〜３μｍ、短径が約０．
０２〜０．５μｍである場合が多い。The micropores 3 and 4 in the PP portion 1 and the PE portion 2 are oblong or rectangular in shape. The PP part 1 has micropores 3 having a major axis of about 0.05 to 0.3 μm and a minor axis of about 0.01 to 0.1 μm. The PE part 2 has micropores 4 having a major axis. Is about 0.1 to 3 μm and the minor axis is about 0.
In many cases, it is from 02 to 0.5 μm.

【００７２】このようなＰＰ部分およびＰＥ部分の微細
孔形状および孔径を有する多孔質フィルムはセパレータ
として用いた場合、電極構成材料であるリチウムが還元
されて析出する際に生ずる樹枝状結晶（ｄｅｎｄｒｉｔ
ｅ）のセパレータ内部への侵入阻止が有効にできるので
好ましいものである。When the porous film having the fine pore shape and pore size of the PP portion and the PE portion is used as a separator, a dendrite formed when lithium as an electrode constituent material is reduced and deposited.
This is preferable because it is possible to effectively prevent the e) from entering the inside of the separator.

【００７３】本発明に係る多孔質フィルムはＰＰとＰＥ
を必須成分として含む組成物を用い、この組成物を上記
と同様にフィルム成形し、次いでアニーリングおよび低
温延伸を施した後、６０℃〜（Ｔｍｂ−５）℃の温度で
再び延伸（以下、この温度での延伸を「高温延伸」と称
す）して得ることもできる。The porous film according to the present invention is made of PP and PE.
Is used as an essential component, the composition is formed into a film in the same manner as above, and then subjected to annealing and low-temperature stretching, and then stretched again at a temperature of 60 ° C. to (Tmb-5) ° C. (hereinafter, this Stretching at a temperature is referred to as "high temperature stretching").

【００７４】この高温延伸は一軸延伸あるいは二軸延伸
のいずれであってもよい。また、その延伸方向は前記低
温延伸の方向と同じであってもよく、あるいは異なって
いてもよい。ただし、延伸時の温度が低過ぎるとフィル
ムの破断が生じ易くなり、高過ぎると得られる多孔質フ
ィルムの電気抵抗値が高くなるので、延伸温度は上記範
囲に設定して行なう。This high temperature stretching may be either uniaxial stretching or biaxial stretching. The stretching direction may be the same as or different from the low temperature stretching direction. However, if the temperature during stretching is too low, the film tends to break, and if it is too high, the electrical resistance value of the resulting porous film becomes high, so the stretching temperature is set within the above range.

【００７５】かような高温延伸を施して得られる多孔質
フィルムのミクロ構造は、前記低温延伸により得られる
ものと同じであるが、その気孔率が高く、従って、電気
抵抗がより低いものである。なお、高温延伸時の延伸率
は通常約１０〜５００％である。この延伸率（Ｍ2 ％）
は下記の数３により表される。数３中におけるＬ2 は、
高温延伸後の寸法、Ｌ1 は低温延伸後の寸法（即ち、高
温延伸前の寸法）である。The microstructure of the porous film obtained by such high temperature drawing is the same as that obtained by the above low temperature drawing, but its porosity is high and therefore its electric resistance is lower. . The stretching ratio at the time of high temperature stretching is usually about 10 to 500%. This draw ratio (M 2 %)
Is represented by the following expression 3. L 2 in the equation 3 is
The dimension after high temperature stretching, L 1 is the dimension after low temperature stretching (that is, the dimension before high temperature stretching).

【００７６】[0076]

【数３】 [Equation 3]

【００７７】また、前記の低温延伸あるいは高温延伸を
施して得られる多孔質フィルムは延伸時に作用する応力
が残留し、延伸方向の寸法が収縮し易いので、延伸後に
その延伸方向の寸法を予め熱収縮させることにより、寸
法安定性のよい多孔質フィルムを得ることもできる。こ
の熱収縮は延伸温度と同程度の温度で行なうのが好まし
い。熱収縮の度合いは限定されないが、通常、延伸後の
フィルム長さが約１５〜３５％減少する程度とする。Since the porous film obtained by the above-mentioned low-temperature stretching or high-temperature stretching retains the stress acting during the stretching and the dimension in the stretching direction easily shrinks, the dimension in the stretching direction is preliminarily heated after stretching. By shrinking, a porous film having good dimensional stability can also be obtained. This heat shrinkage is preferably carried out at a temperature about the same as the stretching temperature. The degree of heat shrinkage is not limited, but is usually such that the length of the film after stretching is reduced by about 15 to 35%.

【００７８】なお、多孔質フィルムにおける延伸方向の
寸法が変化しないように規制し、延伸温度またはそれ以
上の温度で加熱する所謂「ヒートセット」を施すことに
よっても、熱収縮処理を施すのと同様に寸法安定性の優
れた多孔質フィルムを得ることができる。勿論、熱収縮
およびヒートセットの両方を施すこともできる。The heat shrinking treatment is also carried out by performing so-called "heat setting" in which the dimension of the porous film in the stretching direction is regulated so as not to change and heating is performed at a stretching temperature or higher. A porous film having excellent dimensional stability can be obtained. Of course, both heat shrinkage and heat setting can be performed.

【００７９】上記のような方法によって得られる本発明
の多孔質フィルムは、室温において有機電解液中で測定
した電気抵抗値が１枚当り５Ω・ｃｍ2 以下と低く、電
池用セパレータとして好ましいものである。The porous film of the present invention obtained by the above method has a low electric resistance value of 5 Ω · cm 2 or less per sheet measured at room temperature in an organic electrolytic solution, and is preferable as a battery separator. is there.

【００８０】そして、このセパレータは１２０〜１５０
℃の領域内の特定温度において、その抵抗値が室温の抵
抗値の数十倍以上〜数百倍以上に急増し、１枚当りの電
気抵抗値が２００Ω・ｃｍ2 以上となり、ＳＤ特性に優
れたものである。また、増大した電気抵抗は、ＳＤ開始
温度よりも少なくとも２５℃高い温度まで維持されるこ
とも確認され、耐熱温度も高く、安全性の優れたもので
あることが確認された。The separator is 120 to 150.
At a specific temperature in the range of ℃, its resistance value rapidly increases to several tens of times to several hundreds of times that of room temperature, and the electrical resistance value per sheet is 200 Ω · cm 2 or more, which is excellent in SD characteristics. It is a thing. It was also confirmed that the increased electric resistance was maintained at a temperature at least 25 ° C. higher than the SD start temperature, and the heat resistance temperature was also high, and it was confirmed that the safety was excellent.

【００８１】また、本発明に係る多孔質フィルムは電池
用セパレータの他、分離膜、建築用通気性フィルム、衣
料用通気性フィルム等広い用途に適用できる。The porous film according to the present invention can be applied to a wide range of applications such as separators for batteries, separation membranes, breathable films for construction, breathable films for clothing.

【００８２】[0082]

【実施例】以下、実施例により本発明を更に詳細に説明
する。なお、実施例および比較例中における「％」、
「Ｍｗ」および「Ｍｎ」は、各々「重量％」、「重量平
均分子量」および「数平均分子量」を意味する。EXAMPLES The present invention will be described in more detail below with reference to examples. Incidentally, "%" in the examples and comparative examples,
"Mw" and "Mn" mean "wt%", "weight average molecular weight", and "number average molecular weight", respectively.

【００８３】実施例１ 融点（以下、ｍｐと称す）１６６℃、メルトインデック
ス（以下、「ＭＩ」と称す）２．５（ｇ／１０ｍｉ
ｎ）、Ｍｗ／Ｍｎが８．５のアイソタクチックＰＰと、
ｍｐ１３９℃、ＭＩ０．７５、Ｍｗ／Ｍｎが８．６、密
度（以下、「ｄ」と称す）０．９６２ｇ／ｃｍ3 の高密
度ＰＥの同重量を溶融混合し、Ｔダイ押出機により厚さ
３８μｍの長尺のフィルムに成形する。なお、成形条件
はダイス温度２３０℃、Ｔダイリップ間隙３ｍｍ、引取
速度４０ｍ／ｍｉｎ、ドラフト比１６０とした。このフ
ィルムは外観上のムラや厚さのバラツキも少ない良好な
ものであった。Example 1 Melting point (hereinafter referred to as mp) 166 ° C., melt index (hereinafter referred to as “MI”) 2.5 (g / 10 mi)
n), isotactic PP having Mw / Mn of 8.5,
mp 139 ° C, MI 0.75, Mw / Mn 8.6, density (hereinafter referred to as "d") 0.962 g / cm 3 of the same weight of high-density PE is melt-mixed and the thickness is obtained by a T-die extruder. It is formed into a long film of 38 μm. The molding conditions were a die temperature of 230 ° C., a T-die lip gap of 3 mm, a take-up speed of 40 m / min, and a draft ratio of 160. This film was a good one with little unevenness in appearance and variation in thickness.

【００８４】次に、このフィルムと厚さ５０μｍのポリ
エチレンテレフタレートフィルムを重ね合わせてガラス
管にロール状に巻付け、これを温度１６７℃に保った乾
燥機中で２時間アニーリングする。Then, this film and a polyethylene terephthalate film having a thickness of 50 μm are superposed on each other and wound around a glass tube in a roll shape, and this is annealed in a dryer kept at a temperature of 167 ° C. for 2 hours.

【００８５】アニーリング後、ガラス管から巻き戻し、
温度２５℃にて長尺方向（フィルム成形時における引取
方向、以下の実施例および比較例において同じ）に延伸
率が２００％になるように低温延伸し、更に温度９５℃
にて同方向に延伸率が２００％になるように高温延伸す
る。After annealing, rewind from the glass tube,
At a temperature of 25 ° C., the film was stretched at a low temperature in the long direction (the take-up direction during film formation, the same in the following Examples and Comparative Examples) so that the stretching ratio was 200%, and the temperature was 95 ° C.
At this time, high temperature drawing is performed in the same direction so that the drawing ratio becomes 200%.

【００８６】そして、延伸後、温度９５℃の雰囲気中に
おいて延伸方向の寸法を延伸状態のフィルム長さを基準
に２０％収縮させ、更に延伸方向の寸法を規制して同温
度で２分間加熱してヒートセットすることにより、多孔
質フィルムを得た。After stretching, the dimension in the stretching direction is shrunk by 20% based on the length of the stretched film in an atmosphere at a temperature of 95 ° C., the dimension in the stretching direction is regulated, and the film is heated at the same temperature for 2 minutes. A porous film was obtained by heat setting.

【００８７】この多孔質フィルムは真珠状光沢を帯びた
もので、延伸方向に平行および垂直な切断面をＴＥＭに
より観察したところ、図１に示すのと同様にＰＰ部分と
ＰＥ部分が互いに独立して存在する相分離構造を有して
おり、ＰＰ部分が多孔質の連続相として存在し、一方、
ＰＥ部分が厚さ約０．１〜１μｍの非連続相として存在
（ＰＰの連続相中に点在）するものであり、該ＰＥ部分
も多孔質構造を有するものであった。This porous film had a pearlescent luster, and when the cross sections parallel and perpendicular to the stretching direction were observed by TEM, it was found that the PP portion and the PE portion were independent from each other as shown in FIG. Have a phase-separated structure, and the PP portion exists as a porous continuous phase, while
The PE portion was present as a discontinuous phase having a thickness of about 0.1 to 1 μm (dotted in the continuous phase of PP), and the PE portion also had a porous structure.

【００８８】また、ＳＥＭによる表面観察によりＰＰ部
分における最大の孔（楕円形）はその短径が約０．１μ
ｍ、長径が約０．３μｍであり、ＰＥ部分における最大
の孔（楕円形）はその短径が約０．３μｍ、長径が約２
μｍであった。Further, the surface observation by SEM shows that the largest hole (elliptical shape) in the PP portion has a minor axis of about 0.1 μm.
m, the major axis is about 0.3 μm, and the largest hole (ellipse) in the PE part has a minor axis of about 0.3 μm and a major axis of about 2
was μm.

【００８９】この多孔質フィルムは厚さが２９μｍであ
り、外観上のムラもない良好なものであった。そして、
延伸方向の引張弾性率は４９００ｋｇ／ｃｍ2 であり、
室温での電気抵抗は２．２Ω・ｃｍ2 であった。この多
孔質フィルムのＳＤ特性を図２に示す。This porous film had a thickness of 29 μm and was good without unevenness in appearance. And
The tensile elastic modulus in the stretching direction is 4900 kg / cm 2 ,
The electric resistance at room temperature was 2.2 Ω · cm 2 . The SD characteristics of this porous film are shown in FIG.

【００９０】なお、使用したＰＥおよびＰＰの分子量、
ｍｐ、ＭＩ、ｄおよび多孔質フィルムの特性は下記要領
により測定した。The molecular weights of PE and PP used were
The properties of mp, MI, d and the porous film were measured by the following procedures.

【００９１】（高温ＧＰＣによる分子量）溶媒としてＯ
−ジクロロベンゼンを用い、１３５℃にてＷａｔｅｒｓ
社製のＧＰＣ−１５０Ｃを用いて測定した。そして、カ
ラムとしてはＳｈｏｄｅｘ ＫＦ−８０Ｍ（昭和電工社
製）、データ処理にはＴＲＣ社製ＧＰＣデータ処理シス
テムを用いた。分子量（Ｍｗ、Ｍｎ）はポリスチレンを
基準として算出した。(Molecular weight by high temperature GPC) O as a solvent
-Waters at 135 ° C with dichlorobenzene
It measured using GPC-150C by the company. Then, Shodex KF-80M (manufactured by Showa Denko KK) was used as a column, and a GPC data processing system manufactured by TRC was used for data processing. The molecular weight (Mw, Mn) was calculated based on polystyrene.

【００９２】（ｍｐ）セイコー電子工業社製のＤＳＣ２
００を用い、ＰＥまたはＰＰを室温から２２０℃まで１
０℃／ｍｉｎの割合で昇温させ、２２０℃に３０分間保
持し、次いでこれを室温まで約２℃／ｍｉｎの割合で冷
却する。次に、１０℃／ｍｉｎの割合で昇温させ、この
昇温過程での吸熱ピーク値での温度をｍｐとした。(Mp) DSC2 manufactured by Seiko Instruments Inc.
00, PE or PP from room temperature to 220 ° C 1
The temperature is raised at a rate of 0 ° C./min, the temperature is maintained at 220 ° C. for 30 minutes, and then the temperature is cooled to room temperature at a rate of about 2 ° C./min. Next, the temperature was raised at a rate of 10 ° C./min, and the temperature at the endothermic peak value during this heating process was taken as mp.

【００９３】（ＭＩ）ＡＳＴＭ Ｄ １２３８に準じて
測定した。単位は「ｇ／１０ｍｉｎ」である。(MI) Measured according to ASTM D 1238. The unit is “g / 10 min”.

【００９４】（ｄ）ＡＳＴＭ Ｄ １５０５に準じて測
定した。単位は「ｇ／ｃｍ3 」である。(D) Measured according to ASTM D 1505. The unit is “g / cm 3 ”.

【００９５】（引張弾性率）株式会社島津製作所製オー
トグラフＡＧ−２０００Ａを用い、チャック間隔１００
ｍｍ、引張速度２０ｍｍ／ｍｉｎ、温度２５℃の条件で
５％歪みでの応力を測定し、算出した。なお、測定試料
片の幅は１０ｍｍとした。(Tensile Elastic Modulus) An autograph AG-2000A manufactured by Shimadzu Corporation was used and the chuck interval was 100.
The stress at 5% strain was measured and calculated under conditions of mm, tensile rate of 20 mm / min, and temperature of 25 ° C. The width of the measurement sample piece was 10 mm.

【００９６】（電気抵抗）測定はＪＩＳ Ｃ ２３１３
に準じて行なった。電解液としてはプロピレンカーボネ
ートと１，２−ジメトキシエタンを同容量ずつ混合した
液に、電解質として無水過塩素酸リチウムを１モル／リ
ットルの濃度になるよう溶解したものを用いた。(Electrical resistance) is measured according to JIS C 2313.
Was carried out according to. As the electrolytic solution, a solution prepared by mixing propylene carbonate and 1,2-dimethoxyethane in equal volumes, and dissolving anhydrous lithium perchlorate as an electrolyte to a concentration of 1 mol / liter was used.

【００９７】そして、国洋電気工業社製の抵抗計、ＬＣ
ＲメーターＫＣ−５３２により１ＫＨｚの交流抵抗を測
定し、下記数４により多孔質フィルムの電気抵抗値Ｒ
（Ω・ｃｍ2 ）を算出した。なお、数４中のＲ0 は電解
液の電気抵抗値（Ω) 、Ｒ1 は電解液中に多孔質フィル
ムを浸漬した状態で測定した電気抵抗値（Ω）、Ｓは多
孔質フィルムの断面積（ｃｍ2 ）である。And a resistance meter, LC manufactured by Kuniyo Denki Kogyo Co., Ltd.
The AC resistance of 1 KHz was measured by an R meter KC-532, and the electric resistance value R of the porous film was calculated by the following equation 4.
(Ω · cm 2 ) was calculated. In Equation 4, R 0 is the electric resistance value (Ω) of the electrolytic solution, R 1 is the electric resistance value (Ω) measured with the porous film immersed in the electrolytic solution, and S is the disconnection of the porous film. Area (cm 2 ).

【００９８】[0098]

【数４】 [Equation 4]

【００９９】なお、ここで使用している電気抵抗測定セ
ルは若干の漏れ電流があるため、完全に無孔のフィルム
においても最大で６００Ω・ｃｍ2 程度の電気抵抗値し
か測定できないものである。Since the electric resistance measuring cell used here has a slight leakage current, even a completely non-porous film can measure only an electric resistance value of about 600 Ω · cm 2 at maximum.

【０１００】（ＳＤ特性）多孔質フィルムの引取方向の
長さが一定になるように２辺を固定する。そして、これ
を所定の温度に維持した炉中に入れ、１５分間加熱して
取り出し、室温にてその電気抵抗を測定した。(SD characteristics) Two sides are fixed so that the length of the porous film in the take-up direction is constant. Then, this was placed in a furnace maintained at a predetermined temperature, heated for 15 minutes and taken out, and its electric resistance was measured at room temperature.

【０１０１】比較例１アイソタクチックＰＰ（ｍｐ１６
１℃、Ｍｗ／Ｍｎ＝１１．３、ＭＩ２．５）と高密度Ｐ
Ｅ（ｍｐ１４１℃、Ｍｗ／Ｍｎ＝１０．６、ＭＩ０．７
０、ｄ０．９５９）の同重量を溶融混合し、Ｔダイ押出
機により長尺フィルム状に成形する。成形条件はダイス
温度２３０℃、Ｔダイリップ間隙２．５ｍｍ、引取速度
５０ｍ／ｍｉｎ、ドラフト比１４０とした。Comparative Example 1 Isotactic PP (mp16
1 ° C, Mw / Mn = 11.3, MI2.5) and high density P
E (mp 141 ° C., Mw / Mn = 10.6, MI 0.7
0, d0.959) of the same weight are melt mixed, and formed into a long film shape by a T-die extruder. The molding conditions were a die temperature of 230 ° C., a T-die lip gap of 2.5 mm, a take-up speed of 50 m / min, and a draft ratio of 140.

【０１０２】得られたフィルム状物はやや透明性の悪い
白濁部分と透明な島状部分（幅２〜１０ｍｍ、長さ５〜
６０ｍｍ、長さ方向が引取方向と平行）が点在する非常
にムラの大きい外観を有し、その島状部分にはシワが多
く見られる不均一なものであった。このフィルム状物の
厚さは２７〜５３μｍ（平均厚さは４０μｍ）でバラツ
キが大きかった。The obtained film-like material had a slightly opaque white turbid portion and a transparent island-like portion (width 2 to 10 mm, length 5 to 5 mm).
The appearance was very uneven, with 60 mm, and the length direction was parallel to the take-up direction), and there were many wrinkles on the island-shaped portion, which was non-uniform. The thickness of this film-like material was 27 to 53 μm (average thickness was 40 μm), and the variation was large.

【０１０３】このフイルム状物の四辺を固定して１２０
℃に保った乾燥機中で１時間アニーリングし、次いで２
５℃の温度で長尺方向に延伸率が５０％になるように低
温延伸し、更に１００℃にて同方向に延伸率が１００％
になるように高温延伸する。そして、次に延伸方向の寸
法が変化しないように規制して１００℃で５分間加熱し
てヒートセットした。The four sides of this film-like material are fixed to 120
Anneal for 1 hour in a dryer kept at 0 ° C, then 2
At a temperature of 5 ° C, low temperature stretching is performed so that the stretching ratio becomes 50% in the longitudinal direction, and at 100 ° C, the stretching ratio is 100% in the same direction.
Drawing at high temperature. Then, it was regulated so that the dimension in the stretching direction did not change, and heated at 100 ° C. for 5 minutes for heat setting.

【０１０４】かようにして得られたフィルムはわずかに
白化したのみで、厚さ９〜１８μｍ（平均厚さ１３μ
ｍ）であった。そして、その電気抵抗は測定個所により
かなり異なるが平均４６Ω・ｃｍ2 と高く、セパレータ
としては不向きであった。The film thus obtained was only slightly whitened and had a thickness of 9 to 18 μm (average thickness of 13 μm).
m). The electric resistance was considerably different depending on the measurement location, but was high at an average of 46 Ω · cm 2, and was not suitable as a separator.

【０１０５】比較例２ 樹脂の混合割合をＰＰ７０％、ＰＥ３０％とし、ドラフ
ト比を１２０とすること以外は比較例１と同様に作業し
てフィルム状物を成形した。フィルム状物は厚さ２７μ
ｍであり、透明度に多少のムラがある他はほぼ良好なフ
ィルムであった。Comparative Example 2 A film-like material was molded in the same manner as in Comparative Example 1 except that the mixing ratio of the resin was PP 70%, PE 30%, and the draft ratio was 120. The thickness of the film is 27μ
It was m, and the film was almost good except that the transparency was slightly uneven.

【０１０６】このフィルム状物を比較例１と同様にアニ
ーリングおよび延伸し、更にヒートセットして、外観上
ややムラのある白化した多孔質フィルム（厚さ１３μ
ｍ）を得た。この多孔質フィルムの電気抵抗は測定個所
によりかなり異なるが平均６４Ω・ｃｍ2 と高く、セパ
レータとしては不向きであった。This film-like material was annealed and stretched in the same manner as in Comparative Example 1, and then heat set to give a whitened porous film having a slightly uneven appearance (thickness: 13 μm).
m) was obtained. Although the electric resistance of this porous film varied considerably depending on the measurement location, it was as high as 64 Ω · cm 2 on average and was not suitable as a separator.

【０１０７】比較例３ 比較例１で用いたのと同じアイソタクチックＰＰとｍｐ
１４２℃、Ｍｗ／Ｍｎ＝１６．８、ＭＩ０．７０、ｄ
０．９６４の高密度ＰＥの同重量を溶融混合し、Ｔダイ
押出機により長尺フィルム状に成形する。成形条件はダ
イス温度２５０℃、Ｔダイリップ間隙２．３ｍｍ、引取
速度１４ｍ／ｍｉｎ、ドラフト比１１０とした。Comparative Example 3 The same isotactic PP and mp used in Comparative Example 1 were used.
142 ° C, Mw / Mn = 16.8, MI 0.70, d
The same weight of 0.964 high-density PE is melt mixed and formed into a long film by a T-die extruder. The molding conditions were a die temperature of 250 ° C., a T-die lip gap of 2.3 mm, a take-up speed of 14 m / min, and a draft ratio of 110.

【０１０８】得られたフィルム状物は比較例１のものと
同様に主たるやや白濁した部分にやや透明な島状部分
（幅２〜８ｍｍ、長さ５〜６０ｍｍ）が点在する外観を
有し、その島状部分にはシワが多く見られた。このフィ
ルム状物の厚さは２４〜４４μｍ（平均厚さは３３μ
ｍ）とバラツキが大きかった。また、白濁部分は厚く、
透明部分は薄かった。The obtained film-like product had an appearance similar to that of Comparative Example 1 in which the main slightly cloudy part was dotted with slightly transparent island parts (width 2 to 8 mm, length 5 to 60 mm). , There were many wrinkles on the island. The thickness of this film-like material is 24-44 μm (the average thickness is 33 μm).
m) and the variation was large. Also, the cloudy part is thick,
The transparent part was thin.

【０１０９】このフィルムを１１５℃で３０分間アニー
リングし、次いで２５℃の温度で長尺方向に延伸率が１
５０％になるように低温延伸した後、延伸方向の寸法が
変化しないように規制して９０℃で２分間加熱した。This film was annealed at 115 ° C. for 30 minutes and then stretched at a temperature of 25 ° C. in a longitudinal direction of 1%.
After stretching at a low temperature so as to be 50%, the size was regulated so as not to change the dimension in the stretching direction and heated at 90 ° C. for 2 minutes.

【０１１０】かようにして得られたフィルムの厚さは１
１〜２５μｍ（平均１８μｍ）、電気抵抗は７．６Ω・
ｃｍ2 であった。The thickness of the film thus obtained is 1
1 to 25 μm (average 18 μm), electric resistance 7.6Ω
It was cm 2 .

【０１１１】比較例４ 比較例３の場合と同様にして成形したフィルム状物を温
度１６５℃で１０分間アニーリングする。なお、アニー
リングは比較例１と同じ方法で行った。Comparative Example 4 A film-like product molded in the same manner as in Comparative Example 3 is annealed at a temperature of 165 ° C. for 10 minutes. The annealing was performed in the same manner as in Comparative Example 1.

【０１１２】そして、これを２５℃で長尺方向に延伸率
が２００％になるように低温延伸し、更に、温度１１０
℃で同方向に延伸率が１５０％になるように高温延伸
し、その後延伸方向の寸法が変化しないように規制しな
がら温度１００℃で５分間加熱してヒートセットした。
この条件では低温延伸あるいは高温延伸に際し、フィル
ムの破断が生じ易いので充分に注意しながら行わなけれ
はならず、作業性が悪かった。そして、得られたフィル
ムは白色部と透明部が混在するムラの多いもので、厚さ
のバラツキも大きかった。また、このフィルムの電気抵
抗値は１．５Ω・ｃｍ2 であった。Then, this was stretched at 25 ° C. in the longitudinal direction at a low temperature so that the stretching ratio was 200%, and further, at a temperature of 110 ° C.
High temperature drawing was performed at a temperature of 100 ° C. in the same direction so that the drawing ratio was 150%, and thereafter, heating was performed at a temperature of 100 ° C. for 5 minutes while controlling so that the dimension in the drawing direction did not change, and heat set.
Under these conditions, the film is liable to break during low temperature stretching or high temperature stretching, so it must be done with sufficient care, and workability was poor. Then, the obtained film had a lot of unevenness in which a white part and a transparent part were mixed, and the variation in thickness was large. The electric resistance value of this film was 1.5 Ω · cm 2 .

【０１１３】実施例２ 樹脂の混合割合をＰＰ６０％、ＰＥ４０％とし、ドラフ
ト比を１８０とすること以外は実施例１と同様に作業し
て厚さ３５μｍの良好なフィルム状物を成形した。この
フィルム状物を比較例１と同じ方法により温度１６０℃
で１０分間アニーリングし、次に２５℃で長尺方向に延
伸率が２００％になるように低温一軸延伸し、更に、１
１０℃で同方向に２００％高温一軸延伸する。そして、
延伸方向の寸法が変化しないように規制して１１０℃で
５分間加熱してヒートセットし多孔質フィルムを得た。Example 2 A good film-like material having a thickness of 35 μm was formed in the same manner as in Example 1 except that the resin mixing ratios were 60% PP and 40% PE, and the draft ratio was 180. This film-like material was heated at a temperature of 160 ° C.
At 10 ° C. for 10 minutes, then uniaxially stretched at 25 ° C. at a low temperature so that the stretch ratio becomes 200% in the longitudinal direction, and further 1
200% high temperature uniaxial stretching in the same direction at 10 ° C. And
It regulated so that the dimension in the stretching direction would not change, and heated at 110 ° C. for 5 minutes and heat set to obtain a porous film.

【０１１４】この多孔質フィルムは真珠光沢を帯びたも
ので、延伸方向に平行および垂直な切断面をＴＥＭによ
り観察したところ、実施例１の多孔質フィルムと同様に
ＰＰ部分とＰＥ部分が互いに独立して存在する相分離構
造を有しており、ＰＰ部分が多孔質の連続相、ＰＥ部分
が非連続相（この非連続相はＰＰの連続相中に点在）で
あり、該ＰＥ部分も多孔質構造を有するものであった。This porous film had a pearlescent luster, and when the cross sections parallel and perpendicular to the stretching direction were observed by TEM, the PP part and the PE part were independent from each other as in the porous film of Example 1. The PP portion is a porous continuous phase, the PE portion is a discontinuous phase (the discontinuous phase is scattered in the continuous phase of PP), and the PE portion is also present. It had a porous structure.

【０１１５】また、ＳＥＭによる表面観察によりＰＰ部
分における最大の孔はその短径が約０．０５μｍ、長径
が約０．２ μｍであり、ＰＥ部分における最大の孔径
はその短径が約０．２μｍ、長径が約１μｍであった。Further, the surface observation by SEM shows that the largest hole in the PP portion has a short diameter of about 0.05 μm and the long diameter of about 0.2 μm, and the largest hole diameter in the PE portion has a short diameter of about 0. The length was 2 μm and the major axis was about 1 μm.

【０１１６】この多孔質フィルムの厚さは２４μｍであ
り、外観上のムラもない良好なものであった。また、延
伸方向の引張弾性率は５３００ｋｇ／ｃｍ2 、電気抵抗
は２．１Ω・ｃｍ2 であった。この多孔質フィルムのＳ
Ｄ特性は図３に示すとおりであった。The thickness of this porous film was 24 μm, which was good without any unevenness in appearance. The tensile elastic modulus in the stretching direction was 5300 kg / cm 2 , and the electric resistance was 2.1 Ω · cm 2 . S of this porous film
The D characteristic was as shown in FIG.

【０１１７】実施例３ 樹脂の混合割合をＰＰ７０％、ＰＥ３０％とし、ドラフ
ト比を１３０とすること以外は実施例１と同様に作業し
て厚さ４７μｍのフィルム状物を成形する。Example 3 A film-like material having a thickness of 47 μm is formed in the same manner as in Example 1 except that the resin mixing ratio is PP 70%, PE 30%, and the draft ratio is 130.

【０１１８】このフィルム状物を比較例１と同じ方法に
より温度１６５℃で３０分間アニーリングし、次に２５
℃で長尺方向に延伸率が２００％になるように低温一軸
延伸し、更に、１００℃で同方向に１００％高温一軸延
伸する。そして、その延伸方向の寸法が変化しないよう
に規制し、１００℃で５分間加熱してヒートセットする
ことにより多孔質フィルムを得た。This film-like material was annealed in the same manner as in Comparative Example 1 at a temperature of 165 ° C. for 30 minutes, then 25
Low temperature uniaxial stretching is performed at a temperature of 100 ° C. in the long direction so that the stretching ratio is 200%, and further 100% high temperature uniaxial stretching is performed at 100 ° C. in the same direction. Then, it was regulated so that the dimension in the stretching direction did not change, and heated at 100 ° C. for 5 minutes and heat set to obtain a porous film.

【０１１９】この多孔質フィルムは真珠光沢を帯びたも
ので、延伸方向に平行な切断面をＴＥＭにより観察した
ところ、ＰＰ部分とＰＥ部分が互いに独立して存在する
相分離構造を有しており、ＰＰ部分が多孔質の連続相、
ＰＥ部分が非連続相であり、該ＰＥ部分はほぼ棒状乃至
紐状形状でＰＰの連続相中に分散しており、ＳＥＭによ
る表面観察によっても多孔質か否かの判別は困難であっ
た。This porous film was pearlescent and had a phase-separated structure in which the PP portion and the PE portion exist independently of each other when the cut surface parallel to the stretching direction was observed by TEM. , PP is a porous continuous phase,
The PE portion was a discontinuous phase, and the PE portion had a rod-like or string-like shape and was dispersed in the continuous phase of PP, and it was difficult to determine whether it was porous or not by observing the surface by SEM.

【０１２０】また、ＳＥＭによる表面観察によりＰＰ部
分における最大の孔はその短径が約０．１μｍ、長径が
約０．２μｍであった。The surface observation by SEM showed that the largest hole in the PP portion had a short diameter of about 0.1 μm and a long diameter of about 0.2 μm.

【０１２１】この多孔質フィルムの厚さは３０μｍであ
り、外観上のムラもない良好なものであった。また、延
伸方向の引張弾性率は６４００ｋｇ／ｃｍ2 、電気抵抗
は０．６７Ω・ｃｍ2 であった。この多孔質フィルムの
ＳＤ特性は図４に示すとおりであった。The thickness of this porous film was 30 μm, and it was good without unevenness in appearance. The tensile elastic modulus in the stretching direction was 6400 kg / cm 2 , and the electric resistance was 0.67 Ω · cm 2 . The SD characteristic of this porous film was as shown in FIG.

【０１２２】実施例４ （アニーリング温度の影響）実施例３で用いたのと同じ
フィルム状物の四辺を固定し、１３０℃、１３５℃、１
４０℃、１４５℃、１５０℃、１５５℃、１６０℃、１
６５℃で各々３０分間アニーリングする。Example 4 (Effect of Annealing Temperature) The same film material as used in Example 3 was fixed on all four sides, and the temperature was 130 ° C., 135 ° C., and 1 ° C.
40 ° C, 145 ° C, 150 ° C, 155 ° C, 160 ° C, 1
Anneal at 65 ° C. for 30 minutes each.

【０１２３】そして、上記各温度でアニーリングしたフ
ィルム状物を温度２５℃で長尺方向に２００％低温一軸
延伸し、次いで、１００℃の温度で延伸方向の寸法を規
制して５分間加熱してヒートセットする。ヒートセット
後、室温でその電気抵抗を測定した結果を図５に示す。The film-like material annealed at each of the above temperatures was uniaxially stretched at a temperature of 25 ° C. at a low temperature of 200% at a low temperature, and then heated at 100 ° C. for 5 minutes while controlling the dimension in the stretching direction. Heat set. The result of having measured the electric resistance at room temperature after heat setting is shown in FIG.

【０１２４】実施例５ アイソタクチックＰＰ（ｍｐ１６６℃、Ｍｗ／Ｍｎ＝
８．５、ＭＩ２．５）６５％と、低密度ＰＥ（ｍｐ１２
７℃、Ｍｗ／Ｍｎ＝３．８、ＭＩ２．１、ｄ０．９３
５）３５％を溶融混合し、Ｔダイ押出機により長尺フィ
ルム状に成形する。成形条件はダイス温度２３０℃、Ｔ
ダイリップ間隙２．５ｍｍ、引取速度４０ｍ／ｍｉｎ、
ドラフト比１８０とした。得られたフィルムは透明性が
高く、厚さは２８μｍであった。Example 5 Isotactic PP (mp 166 ° C., Mw / Mn =
8.5, MI2.5) 65%, low density PE (mp12
7 ° C., Mw / Mn = 3.8, MI2.1, d0.93
5) Melt and mix 35%, and form into a long film by a T-die extruder. Molding conditions are die temperature 230 ℃, T
Die lip gap 2.5 mm, take-up speed 40 m / min,
The draft ratio was 180. The obtained film was highly transparent and had a thickness of 28 μm.

【０１２５】このフィルム状物を温度１６５℃で５分間
アニーリングし、次に、２５℃で長尺方向に延伸率が２
００％になるように低温一軸延伸し、更に１００℃で同
方向に１７５％高温一軸延伸する。そして、延伸方向の
長さを基準として１００℃の温度で１０％熱収縮させた
後、延伸方向の寸法が変化しないように規制して１００
℃で５分間加熱してヒートセットすることにより、白色
の多孔質フィルムを得た。The film-like material was annealed at a temperature of 165 ° C. for 5 minutes, and then stretched at 25 ° C. in a longitudinal direction to a stretching ratio of 2
It is uniaxially stretched at a low temperature so that it becomes 00%, and further uniaxially stretched at a high temperature of 175% at 100 ° C in the same direction. Then, after shrinking by 10% at a temperature of 100 ° C. based on the length in the stretching direction, the length in the stretching direction is regulated so as not to change 100
A white porous film was obtained by heating at 5 ° C. for 5 minutes and heat setting.

【０１２６】この多孔質セパレータは真珠光沢を帯びた
もので、延伸方向に平行な切断面（図１における断面
Ｃ）をＴＥＭにより観察したところ、ＰＰ部分とＰＥ部
分が互いに独立して存在する相分離構造を有しており、
ＰＰ部分が多孔質の連続相、ＰＥ部分が非連続相（この
非連続相はＰＰの連続相中に点在）であり、該ＰＥ部分
は非多孔質構造を有するものであった。This porous separator had a pearlescent luster, and when a cross section (cross-section C in FIG. 1) parallel to the stretching direction was observed by TEM, it was found that the PP portion and PE portion exist independently of each other. It has a separation structure,
The PP portion was a porous continuous phase, the PE portion was a discontinuous phase (the discontinuous phase was scattered in the continuous phase of PP), and the PE portion had a nonporous structure.

【０１２７】また、ＳＥＭによる表面観察によりＰＰ部
分における最大の孔はその短径が約０．０５μｍ、長径
が約０．２５μｍであった。The surface observation by SEM revealed that the largest hole in the PP portion had a short diameter of about 0.05 μm and a long diameter of about 0.25 μm.

【０１２８】この多孔質フィルムの厚さは１７μｍ、電
気抵抗は１．５Ω・ｃｍ2 であり、外観上のムラもない
良好なものであった。また、このセパレータのＳＤ特性
は図６に示すとおりであった。The thickness of this porous film was 17 μm, the electric resistance was 1.5 Ω · cm 2 , and the appearance was good without unevenness. The SD characteristics of this separator were as shown in FIG.

【０１２９】実施例６ ＰＥとしてｍｐ１３８℃、Ｍｗ／Ｍｎ＝９．２、ＭＩ
１．２、ｄ０．９６６の高密度ＰＥを用いること以外は
実施例１と同様に作業して、厚さ３９μｍの長尺フィル
ム状物を成形する。Example 6 mp 138 ° C. as PE, Mw / Mn = 9.2, MI
A long film-like material having a thickness of 39 μm is formed in the same manner as in Example 1 except that high density PE having a density of 1.2 and d0.966 is used.

【０１３０】このフィルム状物を温度１６５℃で１時間
アニーリングし、次に、２５℃で長尺方向に延伸率が２
００％になるように低温一軸延伸し、次に、１１０℃で
同方向に１００％高温一軸延伸する。そして、延伸方向
の長さを基準として１１０℃の温度で１７％熱収縮させ
た後、延伸方向の寸法が変化しないように規制して１０
０℃で５分間加熱してヒートセットすることにより、白
色の多孔質フィルムを得た。This film-like material was annealed at a temperature of 165 ° C. for 1 hour, and then stretched at 25 ° C. in a longitudinal direction at a stretching ratio of 2
Low temperature uniaxial stretching is performed so that it becomes 00%, and then 100% high temperature uniaxial stretching is performed in the same direction at 110 ° C. Then, after heat-shrinking at a temperature of 110 ° C. by 17% based on the length in the stretching direction, the dimension in the stretching direction is restricted so as not to change 10
A white porous film was obtained by heating for 5 minutes at 0 ° C. and heat setting.

【０１３１】この多孔質フィルムは真珠光沢を帯びたも
ので、延伸方向に平行および垂直な切断面をＴＥＭによ
り観察した結果は、ＰＥ部分（非連続相）の厚さが約
０．０５〜０．５μｍであることを除き実施例１とほぼ
同じであった。This porous film had a pearlescent luster, and the results of observing the cut surfaces parallel and perpendicular to the stretching direction by TEM showed that the thickness of the PE portion (discontinuous phase) was about 0.05 to 0. It was almost the same as in Example 1 except that the thickness was 0.5 μm.

【０１３２】また、ＳＥＭによる表面観察によりＰＰ部
分における最大の孔はその短径が約０．１μｍ、長径が
約０．２μｍであり、ＰＥ部分における最大の孔はその
短径が約０．５μｍ、長径が約２．０μｍであった。According to the surface observation by SEM, the largest hole in the PP portion has a short diameter of about 0.1 μm and the long diameter of about 0.2 μm, and the largest hole in the PE portion has a short diameter of about 0.5 μm. The major axis was about 2.0 μm.

【０１３３】そして、この多孔質フィルムの厚さは２５
μｍであり、外観上のムラもない良好なものであった。
また、その延伸方向の引張弾性率は４２００ｋｇ／ｃｍ
2 、電気抵抗は１．８Ω・ｃｍ2 であった。更に、その
ＳＤ特性は図２とほぼ同じであった。The thickness of this porous film is 25
It was μm, and it was a good one without unevenness in appearance.
Further, the tensile elastic modulus in the stretching direction is 4200 kg / cm.
2 and the electric resistance was 1.8 Ω · cm 2 . Further, its SD characteristics were almost the same as in FIG.

【０１３４】実施例７ ドラフト比を１５５とすること以外は実施例２と同様に
作業して、厚さ４０μｍの長尺フィルム状物を成形す
る。Example 7 A long film-like material having a thickness of 40 μm is formed in the same manner as in Example 2 except that the draft ratio is 155.

【０１３５】このフィルム状物を温度１７０℃で１時間
アニーリングし、次に、２５℃で長尺方向に延伸率が２
００％になるように低温一軸延伸し、次に、９５℃で同
方向に２００％高温一軸延伸する。そして、その延伸方
向の長さを基準として９５℃の温度で２０％熱収縮させ
た後、延伸方向の寸法が変化しないように規制して９５
℃で２分間加熱してヒートセットすることにより、白色
の多孔質フィルムを得た。The film-like material was annealed at a temperature of 170 ° C. for 1 hour, and then stretched at 25 ° C. at a stretching ratio of 2 in the longitudinal direction.
Low temperature uniaxial stretching is performed so that it becomes 00%, and then 200% high temperature uniaxial stretching is performed in the same direction at 95 ° C. Then, after heat-shrinking by 20% at a temperature of 95 ° C. based on the length in the stretching direction as a reference, the dimension in the stretching direction is restricted so that it does not change.
A white porous film was obtained by heating at 0 ° C. for 2 minutes and heat setting.

【０１３６】この多孔質フィルムは真珠光沢を帯びたも
ので、延伸方向に平行および垂直な切断面をＴＥＭによ
り観察した結果は、実施例１とほぼ同じであった。ま
た、ＳＥＭによる表面観察によりＰＰ部分における最大
の孔径はその短径が約０．１μｍ、長径が約０．３μｍ
であり、ＰＥ部分における最大の孔径はその短径が約
０．２μｍ、長径が約２．０μｍであった。This porous film had a pearlescent luster, and the results of observing the cut surfaces parallel and perpendicular to the stretching direction with TEM were almost the same as in Example 1. In addition, the maximum hole diameter in the PP part was about 0.1 μm in the minor axis and about 0.3 μm in the major axis as observed by SEM.
The maximum pore diameter in the PE portion was such that the short diameter was about 0.2 μm and the long diameter was about 2.0 μm.

【０１３７】そして、この多孔質フィルムの厚さは２７
μｍであり、外観上のムラもない良好なものであった。
また、延伸方向の引張弾性率は６１００ｋｇ／ｃｍ2 、
電気抵抗は０．７２Ω・ｃｍ2 であった。更に、そのＳ
Ｄ特性は図３とほぼ同じであった。The thickness of this porous film is 27.
It was μm, and it was a good one without unevenness in appearance.
Further, the tensile elastic modulus in the stretching direction is 6100 kg / cm 2 ,
The electric resistance was 0.72 Ω · cm 2 . Furthermore, the S
The D characteristic was almost the same as in FIG.

【０１３８】実施例８ アイソタクチックＰＰ（ｍｐ１６３℃、Ｍｗ／Ｍｎ＝
９．４、ＭＩ２．５）と高密度ＰＥ（ｍｐ１３９℃、Ｍ
ｗ／Ｍｎ＝８．６、ＭＩ０．７５、ｄ０．９６２）の同
重量を溶融混合し、Ｔダイ押出機により長尺フィルム状
に成形する。成形条件は、ダイス温度２５０℃、Ｔダイ
リップ間隙２．３ｍｍ、引取速度１５ｍ／ｍｉｎ、ドラ
フト比１６０とした。得られたフィルム状物の厚さは２
５μｍであった。Example 8 Isotactic PP (mp 163 ° C., Mw / Mn =
9.4, MI2.5) and high-density PE (mp139 ° C, M
The same weight of w / Mn = 8.6, MI 0.75, d 0.962) is melt mixed and formed into a long film shape by a T-die extruder. The molding conditions were a die temperature of 250 ° C., a T-die lip gap of 2.3 mm, a take-up speed of 15 m / min, and a draft ratio of 160. The thickness of the obtained film-like material is 2
It was 5 μm.

【０１３９】このフィルム状物を温度１６５℃で１０分
間アニーリングし、次に、２５℃で長尺方向に延伸率が
１８０％になるように低温一軸延伸し、その後、９５℃
で同方向に７０％高温一軸延伸する。そして、延伸方向
の長さを基準として９５℃の温度で１４％熱収縮させた
後、延伸方向の寸法が変化しないように規制して９５℃
で２分間加熱してヒートセットすることにより、白色の
多孔質フィルムを得た。This film-like material was annealed at a temperature of 165 ° C. for 10 minutes, then uniaxially stretched at 25 ° C. at a low temperature so that the stretching ratio was 180% in the longitudinal direction, and then at 95 ° C.
Then, the film is uniaxially stretched at 70% high temperature in the same direction. Then, after shrinking by 14% at a temperature of 95 ° C. based on the length in the stretching direction, the dimension in the stretching direction is regulated so as not to change to 95 ° C.
By heating for 2 minutes and heat setting, a white porous film was obtained.

【０１４０】この多孔質フィルムの厚さは１８μｍであ
り、外観上のムラもない良好なものであった。また、電
気抵抗は３．１Ω・ｃｍ2 であった。なお、この多孔質
フィルムのミクロ構造は実施例１とほぼ同様であった。
更に、そのＳＤ特性は図２とほぼ同じであった。The thickness of this porous film was 18 μm, which was good without any unevenness in appearance. The electric resistance was 3.1 Ω · cm 2 . The microstructure of this porous film was almost the same as in Example 1.
Further, its SD characteristics were almost the same as in FIG.

【０１４１】実施例９ 実施例１で用いたＰＰと実施例６で用いたＰＥを前者７
０％、後者３０％の割合で溶融混合し、Ｔダイ押出機に
より厚さ３８μｍのフィルム状に成形する。このとき、
ダイス温度２２０℃、リップ間隔２．０ｍｍ、フィルム
引取速度２７ｍ／ｍｉｎ、ドラフト比１００に設定し
た。Example 9 The PP used in Example 1 and the PE used in Example 6 were the former 7
It is melt-mixed at a ratio of 0% and the latter 30%, and is molded into a film having a thickness of 38 μm by a T-die extruder. At this time,
The die temperature was 220 ° C., the lip interval was 2.0 mm, the film take-up speed was 27 m / min, and the draft ratio was 100.

【０１４２】このフィルム状物を２枚のポリエチレンテ
レフタレートフィルム（厚さ５０μｍ）で挟み、表面温
度を１５５℃に調整した金属ロールに１分間接触させて
アニーリングする。This film-like material is sandwiched between two polyethylene terephthalate films (thickness: 50 μm), and is brought into contact with a metal roll whose surface temperature is adjusted to 155 ° C. for 1 minute for annealing.

【０１４３】そして、これをロール延伸機により温度２
５℃にて延伸率が１００％になるように長尺方向に低温
延伸し、次に、温度９５℃にて同方向に延伸率が１３０
％になるように高温延伸し、その後これを温度１１５℃
において延伸方向の長さを２５％収縮（高温延伸後の寸
法を基準として）させることにより白色の多孔質フィル
ムを得た。Then, this was heated at a temperature of 2 by a roll stretching machine.
At a temperature of 5 ° C., low temperature stretching is performed in the long direction so that the stretching ratio is 100%, and then at a temperature of 95 ° C., a stretching ratio of 130% in the same direction.
% So that the temperature becomes 115 ° C.
By shrinking the length in the stretching direction by 25% (based on the dimension after high temperature stretching), a white porous film was obtained.

【０１４４】この多孔質フィルムは真珠光沢を帯びたも
ので、延伸方向に平行および垂直な切断面をＴＥＭによ
り観察した結果は、ＰＥ部分（非連続相）の厚さが約
０．０５〜０．４μｍであることを除き実施例１と同じ
であった。This porous film had a pearlescent luster, and the observation of the cut surfaces parallel and perpendicular to the stretching direction by TEM showed that the thickness of the PE portion (discontinuous phase) was about 0.05 to 0. The same as Example 1 except that the thickness was 0.4 μm.

【０１４５】また、ＳＥＭによる表面観察ではＰＰ部分
における最大の孔はその短径が約０．０５μｍ、長径が
約０．１μｍであり、ＰＥ部分における最大の孔径はそ
の短径が約０．１μｍ、長径が約０．４μｍであった
（表面の一部において孔が潰れている個所があったの
で、この個所を除いて孔径を測定した）。Further, according to the surface observation by SEM, the largest hole in the PP portion has a short diameter of about 0.05 μm and the longest diameter of about 0.1 μm, and the largest hole diameter in the PE portion has a short diameter of about 0.1 μm. The major axis was about 0.4 μm (there was a portion where the hole was crushed on a part of the surface, so the hole diameter was measured excluding this portion).

【０１４６】この多孔質フィルムは厚さ２８μｍ、延伸
方向の引張弾性率は３６００ｋｇ／ｃｍ2 、電気抵抗は
１．６Ω・ｃｍ2 であった。また、この多孔質フィルム
のＳＤ特性は図４とほぼ同じであった。This porous film had a thickness of 28 μm, a tensile elastic modulus in the stretching direction of 3600 kg / cm 2 , and an electric resistance of 1.6 Ω · cm 2 . The SD characteristics of this porous film were almost the same as those in FIG.

【０１４７】比較例５ 実施例１で得られた長尺フィルム状物を１３０℃で２時
間アニーリングした後、２５℃で長尺方向に延伸率が１
００％になるように延伸し、その後１００℃で同方向に
延伸率が１５０％になるように延伸し、次いで、延伸方
向の寸法を規制して１００℃で２分間加熱してヒートセ
ットした。得られたフィルムは厚さ２４μｍ、電気抵抗
は２０Ω・ｃｍ2 であった。Comparative Example 5 The long film-like material obtained in Example 1 was annealed at 130 ° C. for 2 hours, and then stretched at 25 ° C. in the long direction at a stretching ratio of 1
Stretching was performed so that the stretching ratio was 00%, and then stretching was performed at 100 ° C. in the same direction so that the stretching ratio was 150%. Then, the dimension in the stretching direction was regulated, and heating was performed at 100 ° C. for 2 minutes for heat setting. The obtained film had a thickness of 24 μm and an electric resistance of 20 Ω · cm 2 .

【０１４８】比較例６ 実施例１で成形したフィルム状物を１８０℃で１時間ア
ニーリングした（アニーリング方法は実施例１と同
じ）。アニーリング済のフィルム状物は脆くて延伸でき
なかった。Comparative Example 6 The film-like material molded in Example 1 was annealed at 180 ° C. for 1 hour (the annealing method is the same as in Example 1). The annealed film was brittle and could not be stretched.

【０１４９】比較例７ 市販のＰＰ多孔質フィルム（厚さ２５μｍ、気孔率４５
％）について、電気抵抗およびＳＤ特性を測定した。引
張弾性率は６４００ｋｇ／ｃｍ2 、電気抵抗は０．７３
Ω・ｃｍ2 であった。また、ＳＤ特性は図７に示すとお
りであった。Comparative Example 7 Commercially available PP porous film (thickness: 25 μm, porosity: 45)
%) Was measured for electrical resistance and SD characteristics. Tensile elastic modulus is 6400 kg / cm 2 , electric resistance is 0.73
It was Ω · cm 2 . Moreover, the SD characteristics were as shown in FIG.

【０１５０】比較例８ ＰＰを使用しないこと以外は実施例８と同様に作業し
て、厚さ１８μｍの長尺のＰＥフィルム状物を得る。Comparative Example 8 The same procedure as in Example 8 was carried out except that PP was not used, to obtain a long PE film-like material having a thickness of 18 μm.

【０１５１】このフィルム状物を１２０℃で３０分間ア
ニーリングし、次いで、２５℃で長尺方向に延伸率が２
００％になるように一軸延伸し、延伸方向の寸法を規制
して１１０℃で５分間加熱してヒートセットすることに
より、均一に白化した多孔質フィルムを得た。This film-like material was annealed at 120 ° C. for 30 minutes, and then stretched at 25 ° C. in the longitudinal direction to a stretching ratio of 2
The film was uniaxially stretched to be 100%, regulated in the stretching direction and heated at 110 ° C. for 5 minutes for heat setting to obtain a uniformly whitened porous film.

【０１５２】このフィルムは厚さ１４μｍ、延伸方向の
引張弾性率３３００ｋｇ／ｃｍ2 、電気抵抗０．７６Ω
・ｃｍ2 であった。また、このフィルムのＳＤ特性を図
８に示す。図８からＰＥ製多孔質フィルムは、耐熱温度
が低く安全性に問題があることが判る。This film had a thickness of 14 μm, a tensile elastic modulus in the stretching direction of 3300 kg / cm 2 , and an electric resistance of 0.76 Ω.
・ It was cm 2 . The SD characteristics of this film are shown in FIG. It can be seen from FIG. 8 that the PE porous film has a low heat resistant temperature and thus has a problem in safety.

【０１５３】比較例９ キシレン１０００ｇ、デカリン１０００ｇに対し、高密
度ＰＥ（粘度平均分子量５万、ｍｐ１３６℃、ｄ０．９
５）５０ｇを１２０℃で溶解した。次に、粘度平均分子
量３００万の超高分子量ＰＥの微粉末を加えて１４０℃
に加熱し、これを溶解させる。Comparative Example 9 High-density PE (viscosity average molecular weight 50,000, mp 136 ° C., d0.9) against 1000 g of xylene and 1000 g of decalin.
5) 50 g was melted at 120 ° C. Next, a fine powder of ultra-high molecular weight PE with a viscosity average molecular weight of 3,000,000 was added to 140 ° C.
Heat to dissolve it.

【０１５４】この溶液をＴダイ温度１３５℃にて厚さ６
０μｍの長尺フィルム状に押出し、メタノール中で１分
間冷却後、ロール状の芯体に巻き取る。その後、このフ
ィルムをメタノール中に１０分間浸漬してキシレンおよ
びデカリンを抽出除去し、更に風乾する。This solution was made to have a thickness of 6 at a T-die temperature of 135 ° C.
The film is extruded into a 0 μm long film, cooled in methanol for 1 minute, and wound on a roll-shaped core. Then, this film is immersed in methanol for 10 minutes to extract and remove xylene and decalin, and then air-dried.

【０１５５】次いで、このフィルムをロール式延伸機で
温度１００℃で長尺方向に延伸率が２００％になるよう
に延伸して多孔質フィルムを得た。この多孔質フィルム
の厚さは２５μｍ、電気抵抗は４．２Ω・ｃｍ2 、延伸
方向の引張弾性は３４５０ｋｇ／ｃｍ2 であった。ま
た、そのＳＤ特性は図９に示すとおりであった。Then, this film was stretched at a temperature of 100 ° C. in a longitudinal direction so that the stretching ratio was 200% to obtain a porous film by a roll type stretching machine. The thickness of this porous film was 25 μm, the electric resistance was 4.2 Ω · cm 2 , and the tensile elasticity in the stretching direction was 3450 kg / cm 2 . The SD characteristic was as shown in FIG.

【０１５６】比較例１０ 市販のＰＥ製多孔質フィルムのＳＤ特性を図１０に示し
た。なお、この多孔質フィルムは、厚さ３５μｍ、室温
での電気抵抗１．２Ω・ｃｍ2 、引張弾性率３２００ｋ
ｇ／ｃｍ2 であった。Comparative Example 10 SD characteristics of a commercially available PE porous film are shown in FIG. The porous film had a thickness of 35 μm, an electric resistance of 1.2 Ω · cm 2 at room temperature, and a tensile elastic modulus of 3200 k.
It was g / cm 2 .

【０１５７】[0157]

【発明の効果】本発明によれば、引張弾性率が高く、外
観が良好で厚さも均一な多孔質フィルムが得られ、この
多孔質フィルムはセパレータとして用いた場合、電気抵
抗が低く、適当なＳＤ開始温度を示すと共に、耐熱温度
が高く且つ耐熱温度幅が広くて安全性に富むという利点
を有する。また、本発明の方法によれば、簡単な工程で
多孔質フィルムを得ることができる。According to the present invention, a porous film having a high tensile elastic modulus, a good appearance and a uniform thickness can be obtained. When this porous film is used as a separator, it has a low electric resistance and is suitable. In addition to showing the SD start temperature, it has the advantages that it has a high heat resistance temperature and a wide heat resistance temperature range, and is highly safe. Further, according to the method of the present invention, a porous film can be obtained by a simple process.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明に係る多孔質フィルムのミクロ構造を示
す模式図である。FIG. 1 is a schematic view showing a microstructure of a porous film according to the present invention.

【図２】本発明に係る多孔質フィルムのＳＤ特性を示す
グラフである。FIG. 2 is a graph showing SD characteristics of the porous film according to the present invention.

【図３】本発明に係る多孔質フィルムのＳＤ特性を示す
グラフである。FIG. 3 is a graph showing SD characteristics of the porous film according to the present invention.

【図４】本発明に係る多孔質フィルムのＳＤ特性を示す
グラフである。FIG. 4 is a graph showing SD characteristics of the porous film according to the present invention.

【図５】本発明に係る多孔質フィルムにおけるアニーリ
ング温度と電気抵抗との関係を示すグラフである。FIG. 5 is a graph showing a relationship between annealing temperature and electric resistance in the porous film according to the present invention.

【図６】本発明に係る多孔質フィルムのＳＤ特性を示す
グラフである。FIG. 6 is a graph showing SD characteristics of the porous film according to the present invention.

【図７】従来のセパレータのＳＤ特性を示すグラフであ
る。FIG. 7 is a graph showing SD characteristics of a conventional separator.

【図８】従来のセパレータのＳＤ特性を示すグラフであ
る。FIG. 8 is a graph showing SD characteristics of a conventional separator.

【図９】従来のセパレータのＳＤ特性を示すグラフであ
る。FIG. 9 is a graph showing SD characteristics of a conventional separator.

【図１０】従来のセパレータのＳＤ特性を示すグラフで
ある。FIG. 10 is a graph showing SD characteristics of a conventional separator.

【符号の説明】[Explanation of symbols]

１ ＰＰ部分 ２ ＰＥ部分 1 PP part 2 PE part

フロントページの続き (56)参考文献 特開 昭50−111174（ＪＰ，Ａ) 特開 平３−203160（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C08J 9/00 C08L 23/04 - 23/10 Continuation of the front page (56) References JP-A-50-111174 (JP, A) JP-A-3-203160 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) C08J 9 / 00 C08L 23/04-23/10

Claims (19)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】ポリプロピレンとポリエチレンを必須成分
とする組成物から成る多孔質フィルムであり、これら両
者の合計重量中に占めるポリプロピレンの重量割合が１
０〜９０％であり、そして、ポリエチレンは高温ゲルパ
ーミエイションクロマトグラフで測定した重量平均分子
量Ｍｗと数平均分子量Ｍｎの比Ｍｗ／Ｍｎが１０以下で
あることを特徴とする多孔質フィルム。1. A porous film comprising a composition containing polypropylene and polyethylene as essential components, wherein the weight ratio of polypropylene in the total weight of both is 1.
0 to 90%, and polyethylene has a ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn measured by high temperature gel permeation chromatography of 10 or less. 【請求項２】ポリプロピレンとポリエチレンを必須成分
とする組成物から成り、ポリプロピレン部分とポリエチ
レン部分とが互いに独立して存在する相分離構造を有
し、ポリプロピレン部分またはポリエチレン部分の一方
が連続相、他方が非連続相として存在しており、且つ前
記連続相及び非連続層が多孔質であることを特徴とする
多孔質フィルム。2. A composition comprising polypropylene and polyethylene as essential components, which has a phase-separated structure in which a polypropylene part and a polyethylene part exist independently of each other, and one of the polypropylene part and the polyethylene part is the continuous phase and the other is the other. Exists as a discontinuous phase, and the continuous phase and the discontinuous layer are porous. 【請求項３】連続相がポリプロピレン、非連続相がポリ
エチレンにより構成されている請求項２記載の多孔質フ
ィルム。3. The porous film according to claim 2, wherein the continuous phase is polypropylene and the discontinuous phase is polyethylene. 【請求項４】非連続相が厚さ２μｍ以下の薄層である請4. The contract wherein the discontinuous phase is a thin layer having a thickness of 2 μm or less.
求項２または３に記載の多孔質フィルム。The porous film according to claim 2 or 3. 【請求項５】少なくとも一方向の引張弾性率が３５００5. A tensile modulus of elasticity in at least one direction of 3500.
ｋｇ／ｃｍkg / cm 22 以上である請求項１〜４のいずれかに記載The above is any one of Claims 1-4.
の多孔質フィルム。Porous film. 【請求項６】界面活性剤を含有する請求項１に記載の多6. The multi-component according to claim 1, which contains a surfactant.
孔質フィルム。Porous film. 【請求項７】ポリプロピレンとポリエチレンを必須成分7. Polypropylene and polyethylene are essential components
とする組成物から成り、ポリプロピレン部分とポリエチThe composition consists of the polypropylene part and the polyethylene.
レン部分とが互いに独立して存在する相分離構造を有It has a phase-separated structure in which the
し、ポリプロピレン部分またはポリエチレン部分の一方One of the polypropylene or polyethylene parts
が連続相、他方が非連続相として存在しており、且つ前Exists as a continuous phase, the other as a discontinuous phase, and
記連続相が多孔質であることを特徴とする界面活性剤をThe surfactant characterized in that the continuous phase is porous
含有する多孔質フィルム。Porous film containing. 【請求項８】連続相がポリプロピレン、非連続相がポリ8. The continuous phase is polypropylene and the discontinuous phase is poly.
エチレンにより構成されている請求項７記載の多孔質フThe porous fiber according to claim 7, which is composed of ethylene.
ィルム。Film. 【請求項９】非連続相が多孔質構造である請求項７また9. The method according to claim 7, wherein the discontinuous phase has a porous structure.
は８記載の多孔質フィルム。Is the porous film described in 8. 【請求項１０】非連続相が厚さ２μｍ以下の薄層である10. The discontinuous phase is a thin layer having a thickness of 2 μm or less.
請求項７〜９のいずれかに記載の多孔質フィルム。The porous film according to any one of claims 7 to 9. 【請求項１１】少なくとも一方向の引張弾性率が３５０11. A tensile modulus of elasticity in at least one direction of 350.
０ｋｇ／ｃｍ0 kg / cm 22 以上である請求項７〜１０のいずれかにThe above is any one of Claims 7-10.
記載の多孔質フィルム。The porous film described. 【請求項１２】請求項１〜１１のいずれかに記載の多孔12. Pores according to any one of claims 1 to 11.
質フィルムからなる電池用セパレータ。Battery separator made of high quality film. 【請求項１３】有機電解液中における電気抵抗値が５Ω13. The electric resistance value in an organic electrolytic solution is 5Ω.
・ｃｍ・ Cm 22 ／枚以下である請求項１〜１１のいずれかに記/ It is less than or equal to the number of sheets.
載の多孔質フィルムから成る電池用セパレータ。A battery separator made of a porous film. 【請求項１４】ポリプロピレン（この融点をＴｍａ℃と14. Polypropylene (having a melting point of Tma ° C.)
する）とポリエチレン（この融点をＴｍｂ℃とする）をAnd polyethylene (this melting point is Tmb ° C)
必須成分とする組成物をフィルム成形し、このフィルムThe composition of the essential component is formed into a film, and this film is formed.
をＴｍｂ℃〜（Ｔｍａ＋１０）℃の温度で熱処理し、次Is heat-treated at a temperature of Tmb ° C to (Tma + 10) ° C, and then
いで−２０℃〜６０℃の温度で延伸して多孔質化するこIn order to make it porous by stretching at a temperature of -20 ° C to 60 ° C.
とを特徴とする多孔質フィルムの製造法。And a method for producing a porous film. 【請求項１５】ポリプロピレンとポリエチレンを必須成15. Polypropylene and polyethylene are essential components.
分とする組成物をフィルム成形し、このフィルムをＴｍThe composition of
ｂ℃〜（Ｔｍａ＋１０）℃の温度で熱処理し、次いで−Heat treatment at a temperature of b ° C. to (Tma + 10) ° C., then −
２０℃〜６０℃の温度で一軸延伸して多孔質化し、更にUniaxially stretched at a temperature of 20 ° C to 60 ° C to make it porous, and
６０℃〜（Ｔｍｂ−５）℃の温度で再度延伸することをTo re-stretch at a temperature of 60 ° C to (Tmb-5) ° C.
特徴とする多孔質フィルムの製造法。A method for producing a porous film, which is characterized. 【請求項１６】ポリプロピレンとポリエチレンを必須成16. Polypropylene and polyethylene are essential components
分とする組成物をフィルム成形し、このフィルムをＴｍThe composition of
ｂ℃〜（Ｔｍａ＋１０）℃の温度で熱処理し、次いで−Heat treatment at a temperature of b ° C. to (Tma + 10) ° C., then −
２０℃〜６０℃の温度で一軸延伸して多孔質化し、更にUniaxially stretched at a temperature of 20 ° C to 60 ° C to make it porous, and
６０℃〜（Ｔｍｂ−５）℃の温度で再度延伸し、その後Re-stretching at a temperature of 60 ° C to (Tmb-5) ° C, then
多孔質フィルムを熱収縮させることを特徴とする多孔質Porous film characterized by heat-shrinking the porous film
フィルムの製造法。Film manufacturing method. 【請求項１７】高温ゲルパーミエイションクロマトグラ17. A high temperature gel permeation chromatograph.
フで測定した重量平均分子量Ｍｗと数平均分子量ＭｎのOf the weight average molecular weight Mw and the number average molecular weight Mn measured by
比Ｍｗ／Ｍｎが１０以下のポリエチレンを用いる請求項A polyethylene having a ratio Mw / Mn of 10 or less is used.
１４〜１６のいずれかに記載の多孔質フィルムの製造Production of the porous film according to any of 14 to 16
法。Law. 【請求項１８】正極、負極およびこれらの両極間に介在18. A positive electrode, a negative electrode, and an interposition between these two electrodes.
せしめられたセパレータを有し、このセパレータが請求It has a squeezed separator, and this separator claims
項１〜１１のいずれかに記載の多孔質フィルムであるこItem 1. The porous film according to any one of Items 1 to 11.
とを特徴とする電池。A battery characterized by and. 【請求項１９】正極、負極およびこれらの両極間に介在19. A positive electrode, a negative electrode and an interposition between these electrodes.
せしめられたセパレータを有し、このセパレータが請求It has a squeezed separator, and this separator claims
項１２または１３に記載のセパレータであるThe separator according to item 12 or 13. ことを特徴Characterized by
とする電池。And the battery.
JP00263693A 1992-03-30 1993-01-11 Porous film, its production method and its use Expired - Lifetime JP3507092B2 (en)

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JP00263693A JP3507092B2 (en) 1992-03-30 1993-01-11 Porous film, its production method and its use
DE69304587T DE69304587T2 (en) 1992-03-30 1993-03-29 Porous film, process for its production and use
EP19930105193 EP0565938B1 (en) 1992-03-30 1993-03-29 Porous film, process for producing the same, and use
US08/039,907 US5385777A (en) 1992-03-30 1993-03-30 Porous film, process for producing the same, and use of the same

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WO1997044839A1 (en) * 1996-05-22 1997-11-27 Kureha Chemical Industry Co., Ltd. Porous film and separator for batteries comprising porous film
JP4877881B2 (en) * 2000-08-07 2012-02-15 旭化成イーマテリアルズ株式会社 Zinc halogen battery separator
JP3765396B2 (en) * 2001-08-20 2006-04-12 ソニー株式会社 battery
JP5213443B2 (en) * 2005-08-03 2013-06-19 旭化成イーマテリアルズ株式会社 Polyolefin microporous membrane
US8338017B2 (en) 2007-10-12 2012-12-25 Toray Battery Separator Film Co., Ltd. Microporous membrane and manufacturing method
EP2414084B1 (en) * 2009-03-30 2019-01-16 Toray Industries, Inc. Microporous polymeric membranes for use as battery separators
JP5594873B2 (en) * 2010-05-25 2014-09-24 旭化成イーマテリアルズ株式会社 Method for producing polyolefin biaxially stretched porous membrane and polyolefin biaxially stretched porous membrane
JP6153992B2 (en) * 2015-11-30 2017-06-28 住友化学株式会社 Nonaqueous electrolyte secondary battery separator
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JP6683801B2 (en) * 2017-02-09 2020-04-22 積水化学工業株式会社 Microporous synthetic resin film and method for manufacturing the same, separator for electricity storage device, and electricity storage device
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JP7045862B2 (en) 2017-03-24 2022-04-01 旭化成株式会社 Polyolefin microporous membrane and method for producing polyolefin microporous membrane
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