JPH0525305A - Polyethylene porous membrane, its production and battery separator made of the same membrane - Google Patents

Polyethylene porous membrane, its production and battery separator made of the same membrane

Info

Publication number
JPH0525305A
JPH0525305A JP20474991A JP20474991A JPH0525305A JP H0525305 A JPH0525305 A JP H0525305A JP 20474991 A JP20474991 A JP 20474991A JP 20474991 A JP20474991 A JP 20474991A JP H0525305 A JPH0525305 A JP H0525305A
Authority
JP
Japan
Prior art keywords
polyethylene
weight
molecular weight
composition
density polyethylene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP20474991A
Other languages
Japanese (ja)
Other versions
JP2657434B2 (en
Inventor
Kotaro Takita
耕太郎 滝田
Koichi Kono
公一 河野
Tatsuya Takashima
達也 高嶋
Mamoru Tsuneyoshi
衛 恒吉
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.)
Tonen General Sekiyu KK
Original Assignee
Tonen Corp
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Filing date
Publication date
Application filed by Tonen Corp filed Critical Tonen Corp
Priority to JP20474991A priority Critical patent/JP2657434B2/en
Publication of JPH0525305A publication Critical patent/JPH0525305A/en
Application granted granted Critical
Publication of JP2657434B2 publication Critical patent/JP2657434B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Medicinal Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • 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)
  • Cell Separators (AREA)

Abstract

PURPOSE:To provide the subject polyethylene porous membrane excellent in permeability and mechanical strength and having a function capable of cutting off the permeability at low temperatures. CONSTITUTION:A polyethylene porous membrane made of a composition containing an ultrahigh-molecular weight polyethylene, a high-density polyethylene and a low-density polyethylene or a composition containing the ultrahigh- molecular weight polyethylene and the low-density polyethylene.

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、ポリエチレン微多孔
膜、その製造方法及びそれを用いた電池用セパレータに
関し、特に透過性能及び機械的強度に優れるとともに、
低温で透過性を遮断する機能を有するポリエチレン微多
孔膜、その製造方法及びそれを用いた電池用セパレータ
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene microporous membrane, a method for producing the same, and a battery separator using the same, which is particularly excellent in permeation performance and mechanical strength,
The present invention relates to a polyethylene microporous membrane having a function of blocking permeability at low temperatures, a method for producing the same, and a battery separator using the same.

【０００２】[0002]

【従来の技術及び発明が解決しようとする課題】微多孔
膜は、電池用セパレーター、電解コンデンサー用隔膜、
各種フィルター、透湿防水衣料、逆浸透濾過膜、限外濾
過膜、精密濾過膜等の各種用途に用いられている。2. Description of the Related Art Microporous membranes are used for battery separators, electrolytic capacitor diaphragms,
It is used in various applications such as various filters, moisture-permeable waterproof clothing, reverse osmosis filtration membranes, ultrafiltration membranes and microfiltration membranes.

【０００３】従来、ポリオレフィン微多孔膜の製造方法
としては、例えば異種ポリマー等の微粉体からなる孔形
成剤をポリオレフィンに混合してミクロ分散させた後、
孔形成剤を抽出する混合抽出法、ポリオレフィン相を溶
媒でミクロ相分離することにより多孔構造とする相分離
法、異種固体がミクロ分散しているポリオレフィン成形
体に延伸などの歪を与えることにより、異種固体間を界
面破壊して空孔を生じさせて多孔化する延伸法などが用
いられている。しかし、これらの方法では通常分子量が
50万未満程度のポリオレフィンが用いられるため、延伸
による薄膜化及び高強度化には限界があった。Conventionally, as a method for producing a microporous polyolefin membrane, for example, a pore-forming agent composed of a fine powder of a different polymer or the like is mixed with polyolefin and microdispersed,
A mixed extraction method for extracting a pore-forming agent, a phase separation method for forming a porous structure by microphase-separating a polyolefin phase with a solvent, and imparting strain such as stretching to a polyolefin molded body in which a heterogeneous solid is microdispersed, A stretching method or the like is used in which interfaces between different kinds of solids are destroyed to generate pores to make them porous. However, in these methods, the molecular weight is usually
Since polyolefin of less than 500,000 is used, there is a limit to thinning and high strength by stretching.

【０００４】最近、高強度及び高弾性のフィルムに成形
し得る超高分子量ポリオレフィンが開発され、これによ
る高強度の微多孔膜の製造が種々提案された。例えば特
開昭58-5228 号は、超高分子量ポリオレフィンを不揮発
性溶媒に溶解し、この溶液から繊維またはフィルムなど
のゲルを成形し、この溶媒を含むゲルを揮発性溶剤で抽
出処理した後、加熱延伸する方法を開示している。しか
しながら、不揮発性溶媒で高度に膨潤した多孔性組織を
有するゲルは、２方向に延伸しようとしても、高配向の
延伸ができず、網状組織の拡大により破断し易く、得ら
れるフィルムは強度が小さく、また形成される孔径分布
が大きくなるという欠点があった。一方不揮発性溶媒を
揮発性溶剤で抽出した後に乾燥したゲルは、網状組織が
収縮緻密化するが、揮発性溶剤の不均一な蒸発によりフ
ィルム原反にそりが発生し易く、また収縮緻密化によ
り、高倍率の延伸ができないという欠点があった。Recently, an ultra-high molecular weight polyolefin which can be formed into a high-strength and high-elasticity film has been developed, and various methods for producing a high-strength microporous membrane have been proposed. For example, JP-A-58-5228 discloses that ultra-high molecular weight polyolefin is dissolved in a non-volatile solvent, a gel such as a fiber or a film is molded from this solution, and the gel containing this solvent is subjected to extraction treatment with a volatile solvent. A method of heating and stretching is disclosed. However, a gel having a porous structure swollen highly in a non-volatile solvent cannot be stretched in a high orientation even when it is stretched in two directions, and is easily broken due to expansion of a network structure, and the resulting film has low strength. Also, there is a drawback that the distribution of pore diameters formed is large. On the other hand, in the gel dried after extracting the non-volatile solvent with the volatile solvent, the network shrinks and densifies, but uneven evaporation of the volatile solvent tends to cause warpage in the original film, and shrinkage and densification However, there is a drawback that stretching at a high magnification cannot be performed.

【０００５】これに対し、重量平均分子量が、７×105
以上の超高分子量ポリオレフィンを溶媒中で加熱溶解し
た溶液からゲル状シートを成形し、前記ゲル状シート中
の溶媒量を脱溶媒処理により調製し、次いで加熱延伸し
た後、残留溶媒を除去することにより、超高分子量ポリ
オレフィン( ポリエチレン）の微多孔膜を製造する方法
が種々提案されている（特開昭60-242035 号、特開昭61
-495132 号、特開昭61-195133 号、特開昭63-39602号、
特開昭63-273651 号）。On the other hand, the weight average molecular weight is 7 × 10 5.
Molding a gel-like sheet from a solution obtained by heating and dissolving the above ultra-high molecular weight polyolefin in a solvent, adjusting the amount of the solvent in the gel-like sheet by a desolventizing treatment, and then drawing by heating and removing the residual solvent. Have proposed various methods for producing a microporous membrane of ultra-high molecular weight polyolefin (polyethylene) (JP-A-60-242035 and JP-A-61).
-495132, JP-A-61-195133, JP-A-63-39602,
JP-A-63-273651).

【０００６】しかしながら、上記超高分子量ポリオレフ
ィン（ポリエチレン）微多孔膜の製造方法では、いずれ
も超高分子量ポリオレフィンを２軸延伸するために、ま
ずポリオレフィンのある程度希薄な溶液を調製ので、こ
のため得られた溶液は、シート成形するダイス出口でス
ウェルやネックインが大きく、シート成形が困難であ
る。さらにシート中には、溶媒が過剰に含まれているた
め、そのまま延伸しても目的の微多孔膜は得られないの
で脱溶媒処理してシート中の溶媒量を調整する必要があ
る等、多量の溶剤を必要とし、生産性においても問題が
あった。そこで延伸性を損なうことなく、超高分子量ポ
リオレフィンの高濃度溶液からポリオレフィン微多孔膜
を製造することが望まれるようになった。However, in any of the above methods for producing a microporous membrane of ultrahigh molecular weight polyolefin (polyethylene), in order to biaxially stretch the ultrahigh molecular weight polyolefin, a dilute solution of the polyolefin is first prepared. The solution has large swell and neck-in at the exit of the die for sheet formation, and thus sheet formation is difficult. Furthermore, since the solvent is excessively contained in the sheet, the desired microporous membrane cannot be obtained even if it is stretched as it is, so it is necessary to adjust the amount of solvent in the sheet by desolvation treatment. However, there was a problem in productivity as well. Therefore, it has been desired to manufacture a polyolefin microporous film from a high-concentration solution of an ultrahigh molecular weight polyolefin without impairing the stretchability.

【０００７】このような問題を解決することを目的とし
て、本発明者らは、超高分子量ポリオレフィンを含有
し、（重量平均分子量／数平均分子量）の値が特定の範
囲内にある組成物を用いたポリオレフィン微多孔膜の製
造方法を提案した（特開平3-64334 号) 。この方法によ
り、延伸性が良好で、高濃度溶液とすることが可能なポ
リオレフィン組成物からポリオレフィン微多孔膜を製造
することが可能となった。[0007] For the purpose of solving such a problem, the present inventors have found a composition containing ultra-high molecular weight polyolefin and having a value of (weight average molecular weight / number average molecular weight) within a specific range. We proposed a method for producing the polyolefin microporous membrane used (JP-A-3-64334). By this method, it becomes possible to manufacture a polyolefin microporous film from a polyolefin composition which has good stretchability and can be made into a high-concentration solution.

【０００８】ところで、上記ポリオレフィン微多孔膜を
電池、例えばリチウム電池用セパレータ等に用いる場合
には、電極が短絡して電池内部の温度が上昇した時に、
発火等の事故が生じるのを防止する必要がある。このた
め、リチウムの発火以前に溶解してその孔を目詰りさ
せ、電流をシャットダウンさせる機能をセパレータに持
たせる必要がある。ところが上記各微多孔膜においては
微多孔の閉塞による透過性遮断温度が安全性の点で必ず
しも十分に低いものではなく、より一層安全性を向上さ
せるためには、さらに低い温度で電流のシャットダウン
を起こすセパレータとすることが望ましい。By the way, when the above-mentioned polyolefin microporous membrane is used for a battery, for example, a separator for a lithium battery, etc., when the temperature inside the battery rises due to a short circuit between electrodes,
It is necessary to prevent accidents such as ignition. Therefore, it is necessary for the separator to have a function of melting the lithium before it is ignited to clog the hole and shut down the current. However, in each of the above microporous membranes, the permeability cutoff temperature due to microporous blockage is not necessarily sufficiently low in terms of safety, and in order to further improve safety, shut down the current at a lower temperature. It is desirable to make it a separator.

【０００９】したがって本発明の目的は、透過性能及び
機械的強度に優れるとともに、低温で透過性が遮断する
機能を有するポリエチレン微多孔膜を提供することであ
る。Therefore, an object of the present invention is to provide a polyethylene microporous membrane which is excellent in permeability and mechanical strength and has a function of blocking permeability at low temperatures.

【００１０】また本発明のもう一つの目的は、上記ポリ
エチレン微多孔膜を効率良く製造する方法を提供するこ
とである。Another object of the present invention is to provide a method for efficiently producing the above polyethylene microporous membrane.

【００１１】さらに、本発明のもう一つの目的は、上記
ポリエチレン微多孔膜を用いた電池用セパレータを提供
することである。Further, another object of the present invention is to provide a battery separator using the polyethylene microporous membrane.

【００１２】[0012]

【課題を解決するための手段】上記目的に鑑み鋭意研究
の結果、本発明者は、超高分子量ポリエチレンと、高密
度ポリエチレンと、低密度ポリエチレンとを含有する組
成物からなるポリエチレン微多孔膜は、透過性能及び機
械的強度に優れるとともに、低温で透過性が遮断するこ
とを見出した。また本発明者らは、超高分子量ポリエチ
レンと、低密度ポリエチレンとを含有する組成物からな
るポリエチレン微多孔膜もほぼ同様の性能を有すること
を見出した。以上に基づき本発明に想到した。As a result of earnest research in view of the above object, the present inventors have found that a polyethylene microporous membrane made of a composition containing ultrahigh molecular weight polyethylene, high density polyethylene, and low density polyethylene is used. It was found that the permeability is excellent and the mechanical strength is excellent, and the permeability is cut off at a low temperature. The present inventors have also found that a polyethylene microporous membrane made of a composition containing ultrahigh molecular weight polyethylene and low density polyethylene has almost the same performance. The present invention has been made based on the above.

【００１３】すなわち、本発明の第一のポリエチレン微
多孔膜は、重量平均分子量が７×105 以上の超高分子量
ポリエチレン１〜69重量％と、高密度ポリエチレン98〜
１重量％と、低密度ポリエチレン１〜30重量％とを含有
し、前記超高分子量ポリエチレンと、高密度ポリエチレ
ンとを含有する成分の重量平均分子量／数平均分子量が
10〜300 である組成物からなり、厚さが 0.1〜50μｍ、
空孔率が35〜95％、平均貫通孔径が 0.001〜１μｍ、引
張破断強度が200kg/cm2 以上であり、透過性遮断温度が
135 ℃未満であることを特徴とする。That is, the first polyethylene microporous membrane of the present invention comprises 1 to 69% by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and high density polyethylene 98 to
1% by weight and 1 to 30% by weight of low-density polyethylene, and the weight-average molecular weight / number-average molecular weight of the component containing the ultrahigh-molecular-weight polyethylene and high-density polyethylene is
The composition is 10 to 300, and the thickness is 0.1 to 50 μm,
Porosity is 35 ~ 95%, average through hole diameter is 0.001 ~ 1μm, tensile breaking strength is 200kg / cm 2 or more, and permeability cutoff temperature is
It is less than 135 ℃.

【００１４】また本発明の第二のポリエチレン微多孔膜
は、重量平均分子量が７×105 以上の超高分子量ポリエ
チレン30〜90重量％と、低密度ポリエチレン70〜10重量
％とを含有する組成物からなり、厚さが 0.1〜50μｍ、
空孔率が35〜95％、平均貫通孔径が 0.001〜１μｍ、引
張破断強度が200kg/cm2以上であり、透過性遮断温度が1
35 ℃未満であることを特徴とする。The second polyethylene microporous membrane of the present invention is a composition containing 30 to 90% by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and 70 to 10% by weight of low density polyethylene. Made of a material with a thickness of 0.1-50 μm,
Porosity is 35-95%, average through-hole diameter is 0.001-1 μm, tensile breaking strength is 200kg / cm 2 or more, permeability cutoff temperature is 1
It is characterized by being less than 35 ° C.

【００１５】上記第一のポリエチレン微多孔膜を製造す
る本発明の方法は、重量平均分子量が７×105 以上の超
高分子量ポリエチレン１〜69重量％と、高密度ポリエチ
レン98〜１重量％と、低密度ポリエチレン１〜30重量％
とを含有し、前記超高分子量ポリエチレンと、高密度ポ
リエチレンとを含有する成分の重量平均分子量／数平均
分子量が10〜300 である組成物10〜50重量％と、溶媒50
〜90重量％とからなる溶液を調製し、前記溶液をダイよ
り押出し、冷却してゲル状組成物を形成し、前記ゲル状
組成物を前記ポリエチレン組成物の融点＋10℃以下の温
度で延伸し、しかる後残存溶媒を除去することを特徴と
する。The first method of the present invention for producing a microporous polyethylene membrane comprises: 1 to 69% by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more; and 98 to 1% by weight of high density polyethylene. , Low density polyethylene 1-30% by weight
10 to 50% by weight of a composition containing the above ultrahigh molecular weight polyethylene and high density polyethylene, wherein the weight average molecular weight / number average molecular weight of the component is 10 to 300, and a solvent 50
~ 90 wt% solution is prepared, the solution is extruded from a die, cooled to form a gel composition, and the gel composition is stretched at a temperature not higher than the melting point of the polyethylene composition + 10 ° C. After that, the residual solvent is removed.

【００１６】また上記第二のポリエチレン微多孔膜を製
造する本発明の方法は、重量平均分子量が７×105 以上
の超高分子量ポリエチレン30〜90重量％と、低密度ポリ
エチレン70〜10重量％とを含有し、前記超高分子量ポリ
エチレンと、高密度ポリエチレンとからなる組成物10〜
50重量％と、溶媒50〜90重量％とからなる溶液を調製
し、前記溶液をダイより押出し、冷却してゲル状組成物
を形成し、前記ゲル状組成物を前記ポリエチレン組成物
の融点＋10℃以下の温度で延伸し、しかる後残存溶媒を
除去することを特徴とする。Further, the method of the present invention for producing the above-mentioned second polyethylene microporous membrane comprises 30 to 90% by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and 70 to 10% by weight of low density polyethylene. And a composition comprising the above ultrahigh molecular weight polyethylene and high density polyethylene 10 to
A solution consisting of 50% by weight and a solvent of 50 to 90% by weight is prepared, the solution is extruded from a die and cooled to form a gel composition, and the gel composition is formed by melting the polyethylene composition +10 It is characterized in that it is stretched at a temperature of not higher than 0 ° C., and then the residual solvent is removed.

【００１７】さらに本発明の電池用セパレータは、上記
第一又は第二のポリエチレン微多孔膜からなることを特
徴とする。Further, the battery separator of the present invention is characterized by comprising the above-mentioned first or second polyethylene microporous membrane.

【００１８】本発明を以下詳細に説明する。まず本発明
の第一のポリエチレン微多孔膜を形成する組成物につい
て説明する。本発明の第一のポリエチレン微多孔膜は、
重量平均分子量が７×105 以上の超高分子量ポリエチレ
ン１〜69重量％と、高密度ポリエチレン98〜１重量％
と、低密度ポリエチレン１〜30重量％とを含有し、前記
超高分子量ポリエチレンと、高密度ポリエチレンとを含
有する成分の重量平均分子量／数平均分子量が10〜300
である組成物からなる。The present invention is described in detail below. First, the composition for forming the first polyethylene microporous membrane of the present invention will be described. The first polyethylene microporous membrane of the present invention is
Ultra high molecular weight polyethylene with a weight average molecular weight of 7 × 10 5 or more 1 to 69% by weight and high density polyethylene 98 to 1% by weight
And 1 to 30% by weight of low-density polyethylene, and the weight-average molecular weight / number-average molecular weight of the component containing the ultrahigh-molecular-weight polyethylene and high-density polyethylene is 10 to 300.
Which is a composition.

【００１９】上記超高分子量ポリエチレンは、重量平均
分子量が７×105 以上、好ましくは１×106 〜15×106
のものである。重量平均分子量が７×105 未満では、最
大延伸倍率が低く、目的の微多孔膜が得られない。一
方、上限は特に限定的ではないが15×106 を超えるもの
は、ゲル状成形物の形成において、成形性に劣る。上記
超高分子量ポリエチレンの密度は、通常0.93〜0.95g/cm
3 程度である。The ultrahigh molecular weight polyethylene has a weight average molecular weight of 7 × 10 5 or more, preferably 1 × 10 6 to 15 × 10 6.
belongs to. If the weight average molecular weight is less than 7 × 10 5 , the maximum draw ratio is low and the desired microporous membrane cannot be obtained. On the other hand, the upper limit is not particularly limited, but if it exceeds 15 × 10 6 , moldability is poor in forming a gel-like molded product. The density of the above ultra high molecular weight polyethylene is usually 0.93 to 0.95 g / cm
It is about 3 .

【００２０】また本発明において高密度ポリエチレンと
は、通常密度0.935 g/cm3 以上のポリエチレンである。
またその重量平均分子量は７×105 未満のものである
が、分子量の下限としては１×104 以上のものが好まし
い。重量平均分子量が１×104未満では延伸時に破断が
起こりやすくなるため好ましくない。特に重量平均分子
量１×105 以上７×105 未満のものが好ましい。In the present invention, the high-density polyethylene is a polyethylene having a normal density of 0.935 g / cm 3 or more.
The weight average molecular weight is less than 7 × 10 5 , and the lower limit of the molecular weight is preferably 1 × 10 4 or more. If the weight average molecular weight is less than 1 × 10 4 , rupture tends to occur during stretching, which is not preferable. Particularly, those having a weight average molecular weight of 1 × 10 5 or more and less than 7 × 10 5 are preferable.

【００２１】さらに本発明において低密度ポリエチレン
としては、高圧法による分枝状ポリエチレン（ＬＤＰ
Ｅ）及び低圧法による直鎖状の低密度ポリエチレン（Ｌ
ＬＤＰＥ）が挙げられる。Further, as the low density polyethylene in the present invention, a branched polyethylene (LDP) prepared by a high pressure method is used.
E) and linear low density polyethylene (L
LDPE).

【００２２】ＬＤＰＥの場合、その密度は、通常0.91〜
0.93g/cm3 程度であり、またそのメルトインデックス(M
I 190 ℃、2.16 kg 荷重) は、0.1 〜20ｇ/10 分である
のが好ましく、より好ましくは、0.5 〜10ｇ/10 分であ
る。In the case of LDPE, its density is usually 0.91 to
It is about 0.93 g / cm 3 and its melt index (M
I 190 ° C., 2.16 kg load) is preferably 0.1 to 20 g / 10 min, and more preferably 0.5 to 10 g / 10 min.

【００２３】ＬＬＤＰＥの場合、その密度は、通常0.91
〜0.93g/cm3 程度であり、またそのメルトインデックス
(MI 、190 ℃、2.16 kg 荷重) は、0.1 〜25ｇ/10 分で
あるのが好ましく、より好ましくは、0.5 〜10ｇ/10 分
である。In the case of LLDPE, its density is usually 0.91.
~ 0.93g / cm 3 and its melt index
(MI, 190 ° C., 2.16 kg load) is preferably 0.1 to 25 g / 10 minutes, more preferably 0.5 to 10 g / 10 minutes.

【００２４】上述したような各種成分の配合割合は、超
高分子量ポリエチレンが１〜69重量％、好ましくは５〜
30重量％であり、高密度ポリエチレンが98〜１重量％、
好ましくは93〜50重量％であり、低密度ポリエチレンが
１〜30重量％、好ましくは２〜20重量％である。The mixing ratio of the above-mentioned various components is 1 to 69% by weight, preferably 5 to 69% by weight of ultrahigh molecular weight polyethylene.
30% by weight, high density polyethylene 98-1% by weight,
It is preferably 93 to 50% by weight, low density polyethylene is 1 to 30% by weight, and preferably 2 to 20% by weight.

【００２５】超高分子量ポリエチレンが１重量％未満で
は延伸性の向上に寄与する超高分子量ポリエチレンの分
子鎖の絡み合いがほとんど形成されず、高強度の微多孔
膜を得ることができない。一方、69重量％を超えるとポ
リエチレン組成物の溶液の高濃度化の達成が困難とな
る。また高密度ポリエチレンが１重量％未満ではポリエ
チレン組成物の高濃度化の達成が困難であり、98重量％
を超えると超高分子量ポリエチレンが少なく、高強度の
微多孔膜を得ることができない。さらに低密度ポリエチ
レン (ＬＤＰＥ又はＬＬＤＰＥ）が１重量％未満では、
微多孔膜の低温 (135 ℃未満、好ましくは100〜130 ℃)
での透過性遮断が達成されず、また30重量％を超える
と延伸してもラメラ間の開裂が生じず、微多孔が形成さ
れにくくなり、透過性及び機械的強度が十分でなくな
る。When the ultrahigh molecular weight polyethylene is less than 1% by weight, the entanglement of the molecular chains of the ultrahigh molecular weight polyethylene, which contributes to the improvement of the stretchability, is hardly formed, and a high-strength microporous membrane cannot be obtained. On the other hand, if it exceeds 69% by weight, it becomes difficult to achieve a high concentration of the polyethylene composition solution. Further, if the high-density polyethylene is less than 1% by weight, it is difficult to achieve a high concentration of the polyethylene composition.
If it exceeds, the amount of ultra-high molecular weight polyethylene is small and a high-strength microporous membrane cannot be obtained. Further, if the low density polyethylene (LDPE or LLDPE) is less than 1% by weight,
Low temperature of microporous membrane (below 135 ℃, preferably 100-130 ℃)
In the case of exceeding 30% by weight, cleavage between lamellas does not occur even when stretched, micropores are hardly formed, and permeability and mechanical strength are insufficient.

【００２６】ただし、上記構成成分のうち超高分子量ポ
リエチレン及び高密度ポリエチレンについては、両者を
組成物とした時の重量平均分子量／数平均分子量が10〜
300、好ましくは12〜 250である必要がある。重量平均
分子量／数平均分子量が10未満では、平均分子鎖長が大
きく、溶解時の分子鎖同志の絡み合い密度が高くなるた
め、高濃度溶液の調製が困難である。また300 を超える
と、延伸時に低分子量成分の破断が起こり膜全体の強度
が低下する。However, regarding the ultrahigh molecular weight polyethylene and the high density polyethylene among the above constituents, the weight average molecular weight / number average molecular weight when both are made into a composition is from 10 to 10.
It should be 300, preferably 12-250. If the weight average molecular weight / number average molecular weight is less than 10, the average molecular chain length is large and the entanglement density of the molecular chains becomes high during dissolution, making it difficult to prepare a high-concentration solution. On the other hand, when it exceeds 300, the low molecular weight component is broken during stretching, and the strength of the entire film is lowered.

【００２７】なお、重量平均分子量／数平均分子量は、
分子量分布の尺度として用いられるものであり、この分
子量の比が大きくなるほど分子量分布の幅は拡大する。
すなわち重量平均分子量の異なるポリエチレンからなる
組成物においては、組成物の分子量の比が大きいほど、
配合するポリエチレンの重量平均分子量の差が大きく、
また小さいほど重量平均分子量の差が小さいことを示し
ている。The weight average molecular weight / number average molecular weight is
It is used as a measure of the molecular weight distribution, and the larger the ratio of the molecular weights, the wider the width of the molecular weight distribution.
That is, in a composition composed of polyethylene having different weight average molecular weights, the larger the ratio of the molecular weights of the composition,
The difference in the weight average molecular weight of the blended polyethylene is large,
Further, the smaller the value, the smaller the difference in the weight average molecular weight.

【００２８】このような超高分子量ポリエチレンと、高
密度ポリエチレンとは、重量平均分子量が７×105 以上
の超高分子量ポリエチレンと、重量平均分子量が７×10
5 未満の高密度ポリエチレンとを重量平均分子量／数平
均分子量が上記範囲となるように適量混合することによ
って得ることができる。Such ultra-high molecular weight polyethylene and high-density polyethylene include ultra-high molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and weight average molecular weight of 7 × 10 5.
It can be obtained by mixing a high density polyethylene of less than 5 with an appropriate amount such that the weight average molecular weight / number average molecular weight falls within the above range.

【００２９】なお、本発明においては上記超高分子量ポ
リエチレンと高密度ポリエチレンとからなる組成物とし
て、多段重合高密度ポリエチレンも用いることができ
る。ただし、上記多段重合ポリエチレンは、重量平均分
子量が７×105 以上の成分と、重量平均分子量が７×10
5 未満の成分とが、上記分子量分布の関係を満たすとと
もに、重量平均分子量が７×105 以上の成分を１〜69重
量％含有するように重合したものである必要がある。多
段重合ポリエチレンを用いる場合、重量平均分子量が７
×105 以上の成分と、重量平均分子量が７×105 未満の
成分とが、それぞれ上記組成物における超高分子量ポリ
エチレンと、高密度ポリエチレンとに該当するように、
その配合割合を設定すればよい。In the present invention, a multi-stage polymerized high density polyethylene can also be used as the composition comprising the above ultra high molecular weight polyethylene and the high density polyethylene. However, the above multi-stage polyethylene has a weight average molecular weight of 7 × 10 5 or more and a weight average molecular weight of 7 × 10 5.
Less than 5 components and, together with satisfying the relation of the molecular weight distribution, it is necessary that those polymerized so that the weight average molecular weight of the 7 × 10 5 or more components containing 1 to 69 wt%. When using multi-stage polymerized polyethylene, the weight average molecular weight is 7
A component of × 10 5 or more and a component having a weight average molecular weight of less than 7 × 10 5 correspond to the ultra high molecular weight polyethylene and the high density polyethylene in the above composition, respectively,
The mixing ratio may be set.

【００３０】次に本発明の第二の微多孔膜を形成する組
成物について説明する。本発明の第二のポリエチレン微
多孔膜は、重量平均分子量が７×105 以上の超高分子量
ポリエチレン30〜90重量％と、低密度ポリエチレン70〜
10重量％とからなる組成物からなる。Next, the composition for forming the second microporous membrane of the present invention will be described. The second polyethylene microporous membrane of the present invention comprises 30 to 90% by weight of ultra high molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and low density polyethylene 70 to
10% by weight.

【００３１】上記超高分子量ポリエチレンは、上述した
第一の微多孔膜用の組成物と同様のものを用いることが
できる。As the ultra high molecular weight polyethylene, the same composition as the composition for the first microporous membrane described above can be used.

【００３２】また低密度ポリエチレンも、上述した第一
の微多孔膜用の組成物と同様のものを用いることができ
る。As the low density polyethylene, the same composition as the composition for the first microporous membrane described above can be used.

【００３３】上述したような超高分子量ポリエチレン
と、低密度ポリエチレンとの配合割合は、超高分子量ポ
リエチレンが30〜90重量％、好ましくは40〜80重量％で
あり、低密度ポリエチレンが70〜10重量％、好ましくは
60〜20重量％である。The mixing ratio of the ultra high molecular weight polyethylene and the low density polyethylene as described above is 30 to 90% by weight, preferably 40 to 80% by weight of the ultrahigh molecular weight polyethylene and 70 to 10% by weight of the low density polyethylene. % By weight, preferably
60 to 20% by weight.

【００３４】超高分子量ポリエチレンが30重量％未満で
は (低密度ポリエチレンが70重量％を超えると) 、延伸
してもラメラ間の開裂が生じず、微多孔が形成されにく
くなり、透過機能と機械的強度が十分でなくなり、また
超高分子量ポリエチレンが90重量％を超えると (低密度
ポリエチレンが10重量％未満では) 、ポリエチレン組成
物の高濃度化の達成が困難となる。ゆえに目的とする低
温 (135 ℃未満、好ましくは90〜130 ℃) で透過性を遮
断できるポリエチレン微多孔膜を得ることが困難とな
る。When the ultra high molecular weight polyethylene is less than 30% by weight (when the low density polyethylene exceeds 70% by weight), the interlamellar cleavage does not occur even when stretched, micropores are less likely to be formed, and the permeation function and mechanical properties are reduced. If the ultra high molecular weight polyethylene exceeds 90% by weight (low density polyethylene is less than 10% by weight), it becomes difficult to achieve a high concentration of the polyethylene composition. Therefore, it becomes difficult to obtain a polyethylene microporous membrane capable of blocking the permeability at a target low temperature (less than 135 ° C, preferably 90 to 130 ° C).

【００３５】なお、上述したような第一及び第二のポリ
エチレン微多孔膜用のポリエチレン組成物には、必要に
応じて酸化防止剤、紫外線吸収剤、滑剤、アンチブロッ
キング剤、顔料、染料、無機充填剤などの各種添加剤を
本発明の目的を損なわない範囲で添加することができ
る。In the polyethylene composition for the first and second polyethylene microporous membranes as described above, if necessary, an antioxidant, an ultraviolet absorber, a lubricant, an antiblocking agent, a pigment, a dye, an inorganic material. Various additives such as a filler can be added within a range that does not impair the object of the present invention.

【００３６】このようなポリエチレン組成物を用いた本
発明のポリエチレン微多孔膜の製造方法について説明す
る。A method for producing a polyethylene microporous membrane of the present invention using such a polyethylene composition will be described.

【００３７】本発明において、原料となるポリエチレン
組成物の溶液は、上述のポリエチレン組成物を溶媒に加
熱溶解することにより調製する。In the present invention, the solution of the polyethylene composition as the raw material is prepared by heating and dissolving the above-mentioned polyethylene composition in a solvent.

【００３８】この溶媒としては、ポリエチレン組成物を
十分に溶解できるものであれば特に限定されない。例え
ば、ノナン、デカン、ウンデカン、ドデカン、パラフィ
ン油などの脂肪族または環式の炭化水素、あるいは沸点
がこれらに対応する鉱油留分などが挙げられるが、溶媒
含有量が安定なゲル状成形物を得るためにはパラフィン
油のような不揮発性の溶媒が好ましい。The solvent is not particularly limited as long as it can sufficiently dissolve the polyethylene composition. For example, nonane, decane, undecane, dodecane, paraffin oil and other aliphatic or cyclic hydrocarbons, or a mineral oil fraction having a boiling point corresponding to these, etc. To obtain it, a non-volatile solvent such as paraffin oil is preferable.

【００３９】加熱溶解は、ポリエチレン組成物が溶媒中
で完全に溶解する温度で攪拌しながら行う。その温度は
使用する重合体及び溶媒により異なるが、例えば超高分
子量ポリエチレンと高密度ポリエチレンと低密度ポリエ
チレンとからなる組成物 (以後第一のポリエチレン組
成物という。) の場合には140 〜250 ℃の範囲であり、
超高分子量ポリエチレンと低密度ポリエチレンとからな
る組成物 (以後第二のポリエチレン組成物という。) の
場合には140 〜250 ℃の範囲である。また、ポリエチレ
ン組成物溶液の濃度は、第一の組成物の場合10〜50重量
％、好ましくは10〜40重量％であり、また第二の組成物
の場合10〜50重量％、好ましくは10〜30重量％である。
なお、加熱溶解にあたってはポリエチレンの酸化を防止
するために酸化防止剤を添加するのが好ましい。The heating dissolution is carried out with stirring at a temperature at which the polyethylene composition is completely dissolved in the solvent. The temperature varies depending on the polymer and solvent used, but in the case of a composition comprising ultra-high molecular weight polyethylene, high-density polyethylene and low-density polyethylene (hereinafter referred to as the first polyethylene composition), 140 to 250 ° C. Range of
In the case of a composition comprising ultra-high molecular weight polyethylene and low-density polyethylene (hereinafter referred to as the second polyethylene composition), it is in the range of 140 to 250 ° C. The concentration of the polyethylene composition solution is 10 to 50% by weight, preferably 10 to 40% by weight in the case of the first composition, and 10 to 50% by weight, preferably 10 in the case of the second composition. ~ 30% by weight.
In addition, it is preferable to add an antioxidant in order to prevent the polyethylene from being oxidized during heating and dissolution.

【００４０】次にこのポリエチレン組成物の加熱溶液を
ダイスから押し出して成形する。ダイスは、通常偏平な
口金形状をしたシートダイスが用いられるが、２重円筒
状の中空ダイス、インフレーションダイス等も用いるこ
とができる。シートダイスを用いた場合のダイスギャッ
プは通常0.1 〜５mmであり、押出し成形時には140 〜25
0 ℃に加熱される。この際押し出し速度は、通常20〜30
cm／分乃至２〜３ｍ／分である。Next, the heated solution of this polyethylene composition is extruded from a die to be molded. As the die, a sheet die having a flat die shape is usually used, but a double-cylindrical hollow die, an inflation die or the like can also be used. When using sheet dies, the die gap is usually 0.1 to 5 mm, and it is 140 to 25 mm during extrusion molding.
Heat to 0 ° C. At this time, the extrusion speed is usually 20 to 30.
cm / min to 2-3 m / min.

【００４１】このようにしてダイスから押し出された溶
液は、冷却することによりゲル状物に成形される。冷却
は少なくともゲル化温度以下までは50℃/ 分以上の速度
で行うのが好ましい。冷却速度が遅いと結晶化度が上昇
し、延伸に適したゲル状物となりにくい。冷却方法とし
ては、冷風、冷却水、その他の冷却媒体に直接接触させ
る方法、冷媒で冷却したロールに接触させる方法等を用
いることができる。なおダイスから押し出された溶液
は、冷却前あるいは冷却中に、１〜10好ましくは１〜５
の引取比で引き取っても良い。引取比が10以上になると
ネックインが大きくなり、また延伸時に破断を起こしや
すくなり好ましくない。The solution thus extruded from the die is cooled to form a gel. Cooling is preferably performed at a rate of 50 ° C./min or more up to at least the gelation temperature. When the cooling rate is slow, the degree of crystallinity increases and it is difficult to form a gel-like material suitable for stretching. As a cooling method, a method of directly contacting with cold air, cooling water, or other cooling medium, a method of contacting with a roll cooled with a refrigerant, or the like can be used. The solution extruded from the die should be 1-10, preferably 1-5 before or during cooling.
You may collect at the collection ratio of. When the take-up ratio is 10 or more, neck-in becomes large, and breakage easily occurs during stretching, which is not preferable.

【００４２】次にこのゲル状成形物を延伸する。延伸
は、ゲル状成形物を加熱し、通常のテンター法、ロール
法、インフレーション法、圧延法もしくはこれらの方法
の組合せによって所定の倍率で行う。２軸延伸が好まし
く、縦横同時延伸または逐次延伸のいずれでもよいが、
特に同時２軸延伸が好ましい。Next, this gel-like molded product is stretched. The stretching is carried out by heating the gel-like molded product and using a usual tenter method, roll method, inflation method, rolling method or a combination of these methods at a predetermined magnification. Biaxial stretching is preferable, and either longitudinal / transverse simultaneous stretching or sequential stretching may be used.
Simultaneous biaxial stretching is particularly preferable.

【００４３】延伸温度は、ポリエチレン組成物の融点＋
10℃以下、好ましくは結晶分散温度から結晶融点未満の
範囲である。例えば、第一のポリエチレン組成物の場合
は90〜135 ℃で、より好ましくは、110 〜125 ℃の範囲
であり、第二のポリエチレン組成物の場合は90〜135 ℃
で、より好ましくは、110 〜125 ℃の範囲である。延伸
温度が融点＋10℃を超える場合は、樹脂の溶融により延
伸による分子鎖の配向ができない。また、延伸温度が結
晶分散温度未満では、樹脂の軟化が不十分で、延伸にお
いて破膜し易く、高倍率の延伸ができない。The stretching temperature is the melting point of the polyethylene composition +
It is 10 ° C. or less, preferably in the range from the crystal dispersion temperature to below the crystal melting point. For example, in the case of the first polyethylene composition is 90 to 135 ° C, more preferably in the range of 110 to 125 ° C, and in the case of the second polyethylene composition 90 to 135 ° C.
And more preferably in the range of 110 to 125 ° C. If the stretching temperature is higher than the melting point + 10 ° C, the resin cannot be oriented due to the melting of the resin. On the other hand, if the stretching temperature is lower than the crystal dispersion temperature, the softening of the resin is insufficient, the film is easily broken during stretching, and high-stretching cannot be performed.

【００４４】また、延伸倍率は原反の厚さによって異な
るが、１軸方向で少なくとも２倍以上、好ましくは３〜
20倍、面倍率で10倍以上、好ましくは20〜400 倍であ
る。面倍率が10倍未満では延伸が不十分で高弾性、高強
度の微多孔膜が得られない。一方、面倍率が400 倍を超
えると、延伸装置、延伸操作などの点で制約が生じる。Although the draw ratio varies depending on the thickness of the material, it is at least 2 times or more in the uniaxial direction, preferably 3 to.
20 times, 10 times or more in area magnification, preferably 20 to 400 times. If the surface magnification is less than 10 times, the stretching is insufficient and a highly elastic and high-strength microporous membrane cannot be obtained. On the other hand, if the areal magnification exceeds 400 times, there are restrictions on the stretching apparatus and the stretching operation.

【００４５】得られた延伸成形物を溶剤で洗浄し、残留
する溶媒を除去する。洗浄溶剤としては、ペンタン、ヘ
キサン、ヘプタンなどの炭化水素、塩化メチレン、四塩
化炭素などの塩素化炭化水素、三フッ化エタンなどのフ
ッ化炭化水素、ジエチルエーテル、ジオキサンなどのエ
ーテル類などの易揮発性のものを用いることができる。
これらの溶剤はポリエチレン組成物の溶解に用いた溶媒
に応じて適宜選択し、単独もしくは混合して用いる。洗
浄方法は、溶剤に浸漬し抽出する方法、溶剤をシャワー
する方法、またはこれらの組合せによる方法などにより
行うことができる。The stretched molded product obtained is washed with a solvent to remove the residual solvent. Examples of cleaning solvents include hydrocarbons such as pentane, hexane and heptane, chlorinated hydrocarbons such as methylene chloride and carbon tetrachloride, fluorohydrocarbons such as ethane trifluoride, ethers such as diethyl ether and dioxane. A volatile one can be used.
These solvents are appropriately selected according to the solvent used for dissolving the polyethylene composition, and used alone or as a mixture. The cleaning method can be carried out by a method of immersing in a solvent for extraction, a method of showering the solvent, or a combination thereof.

【００４６】上述のような洗浄は、延伸成形物中の残留
溶媒が１重量％未満になるまで行う。その後洗浄溶剤を
乾燥するが、洗浄溶剤の乾燥方法は加熱乾燥、風乾など
の方法で行うことができる。乾燥した延伸成形物は、結
晶分散温度〜融点の温度範囲で熱固定することが望まし
い。The washing as described above is carried out until the residual solvent in the stretch-molded product is less than 1% by weight. After that, the washing solvent is dried, and the washing solvent can be dried by heating, air drying or the like. It is desirable that the dried stretched molded product be heat-set in the temperature range of the crystal dispersion temperature to the melting point.

【００４７】以上のようにして製造したポリエチレン微
多孔膜は、空孔率が35〜95％、平均貫通孔径が 0.001〜
１μｍ、引張破断強度が200kg/cm2 以上であり、透過性
遮断温度が135 ℃未満である。通常、高密度ポリエチレ
ンあるいは超高分子量ポリエチレンによる微多孔の透過
性遮断温度は135 〜145 ℃であることから、リチウム電
池等の電池用セパレータ等としての安全性の点で大幅に
向上したものと言える。また本発明のポリエチレン微多
孔膜の厚さは、用途に応じて適宜選択しうるが、一般に
0.1 〜50μｍであり、好ましくは５〜40μｍにすること
ができる。The polyethylene microporous membrane produced as described above has a porosity of 35 to 95% and an average through pore diameter of 0.001 to
It has a tensile breaking strength of 200 kg / cm 2 or more and a permeability cutoff temperature of less than 135 ° C. Usually, the microporous permeability cutoff temperature of high-density polyethylene or ultra-high-molecular-weight polyethylene is 135 to 145 ° C, so it can be said that it is a significantly improved safety point as a separator for batteries such as lithium batteries. . The thickness of the polyethylene microporous membrane of the present invention can be appropriately selected depending on the application, but in general,
It can be 0.1 to 50 μm, and preferably 5 to 40 μm.

【００４８】なお、得られたポリエチレン微多孔膜は、
必要に応じてさらに、プラズマ照射、界面活性剤含浸、
表面グラフト等で親水化処理することができる。The obtained polyethylene microporous membrane is
If necessary, further plasma irradiation, surfactant impregnation,
It can be hydrophilized by surface grafting or the like.

【００４９】[0049]

【実施例】以下に本発明の実施例を示す。なお、実施例
における試験方法はつぎの通りである。 (1) 分子量及び分子量分布：ウォーターズ（社）製のGP
C 装置を用い、カラムに東ソー（株）製GMH-6 、溶媒に
O-ジクロルベンゼンを使用し、温度135 ℃、流量1.0 ml
/ 分にて、ゲルパーミエーションクロマトグラフィー
（GPC)法により測定。 (2) 引張破断強度：ASTM D882 に準拠して測定。 (3) フィルムの厚さ：断面を走査型電子顕微鏡により測
定。 (4) 透気度：JIS P8117 に準拠して測定。 (5) 透水性：微多孔膜を平膜モジュールに組み込み、蒸
留水／エタノール混合液（50/50 容積比) で親水化処理
を行い、蒸留水で十分に洗浄した後、380 mmHgの水圧を
かけたときの濾液の透過量を測定して求めた。 (6) 平均貫通孔径：上記(5) で記載したモジュールを用
いて、380 mmHgの差圧下で0.05重量％のプルラン（昭和
電工（株）製) の水溶液を循環させたときに、濾液中に
含まれるプルランの濃度を示差屈折率測定から求め、次
式により計算した阻止率が50％になるプルランの分子量
の値から、後述するようなFlory の理論を利用して、孔
径を算出した。 プルランの阻止率＝｛１−（濾液中のプルラン濃度 /原
液中のプルラン濃度）｝×100 溶液状態にある鎖状高分子は球状の糸まり状で、その直
径d は、分子鎖の両末端の２乗平均距離〈γ2 〉に対し
て、近似的に 〔d/2 〕2 ＝〈γ2 〉・・・(1) の関係にあると考えて良い。高分子溶液における粘性と
分子鎖の広がりに関するFlory の理論によると、高分子
の種類に無関係に 〔η〕Ｍ＝2.1 ×1021〈γ2 〉3/2 ・・・(2) が成立するので、式(1) 及び(2) により、固有粘度
〔η〕の測定値と、阻止率が50％になる分子量Ｍとから
鎖状高分子の直径d を算出することができる。このｄを
ポリエチレン微多孔膜の平均孔径とした。 (7) 空孔率：水銀ポロシメータにより測定。 (8) 透過性遮断温度：微多孔膜を枠で固定し、２分間所
定温度下に放置し、透気度が104 sec/100cc を超えた温
度を測定した。 (9) 実効抵抗：プロピレンカーボネートと、1,2-ジメト
キシエタンの１：１混合溶媒に、 LiClO4 を１mol/リッ
トルになるように溶解した電解液を調製し、この電解液
と、ステンレス電極を用い、正負両電極間にセパレータ
(ポリエチレン微多孔膜) を設置してアルゴン雰囲気
中、25℃において測定した複合インピーダンスプロット
から求めた。EXAMPLES Examples of the present invention will be shown below. The test method in the examples is as follows. (1) Molecular weight and molecular weight distribution: GP manufactured by Waters Co., Ltd.
Using C instrument, GOH-6 manufactured by Tosoh Corporation as a column and as a solvent
Using O-dichlorobenzene, temperature 135 ℃, flow rate 1.0 ml
/ Min, measured by gel permeation chromatography (GPC) method. (2) Tensile breaking strength: Measured according to ASTM D882. (3) Film thickness: The cross section was measured with a scanning electron microscope. (4) Air permeability: Measured according to JIS P8117. (5) Water permeability: A microporous membrane was installed in a flat membrane module, treated with a distilled water / ethanol mixture (50/50 volume ratio) to make it hydrophilic, and after sufficiently washing with distilled water, a water pressure of 380 mmHg was applied. It was determined by measuring the amount of permeation of the filtrate when applied. (6) Average through-hole diameter: Using the module described in (5) above, when a 0.05 wt% pullulan (Showa Denko KK) aqueous solution was circulated under a differential pressure of 380 mmHg, it was added to the filtrate. The concentration of pullulan contained was determined from the differential refractive index measurement, and the pore size was calculated from the molecular weight of pullulan having a rejection of 50% calculated by the following equation, using the Flory theory as described later. Retention rate of pullulan = {1- (pullulan concentration in filtrate / pullulan concentration in undiluted solution)} x 100 The chain-like polymer in solution has a spherical thread shape and its diameter d is at both ends of the molecular chain. It can be considered that there is an approximate relationship of [d / 2] 2 = <γ 2 > ... (1) with respect to the root-mean-square distance <γ 2 > of. According to Flory's theory of viscosity and molecular chain spread in polymer solution, [η] M = 2.1 × 10 21 <γ 2 > 3/2 (2) holds regardless of the type of polymer. From equations (1) and (2), the diameter d of the chain polymer can be calculated from the measured value of the intrinsic viscosity [η] and the molecular weight M at which the rejection is 50%. This d was defined as the average pore diameter of the polyethylene microporous membrane. (7) Porosity: Measured with a mercury porosimeter. (8) Permeability cut-off temperature: The microporous membrane was fixed with a frame, left at a predetermined temperature for 2 minutes, and the temperature at which the air permeability exceeded 10 4 sec / 100 cc was measured. (9) Effective resistance: LiClO 4 was dissolved in a 1: 1 mixed solvent of propylene carbonate and 1,2-dimethoxyethane to a concentration of 1 mol / liter to prepare an electrolytic solution. Use a separator between the positive and negative electrodes
(Polyethylene microporous membrane) was installed, and it was determined from a composite impedance plot measured at 25 ° C. in an argon atmosphere.

【００５０】実施例１ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)20重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)66.7重量％と、メルトインデックス(MI、190
℃、2.16kg荷重) 2.0 ｇ/10分の低密度ポリエチレン(LD
PE)13.3重量％とを混合した原料樹脂15重量部と、流動
パラフィン（64cst/40℃）85重量部とを混合し、ポリエ
チレン組成物の溶液を調製した。次にこのポリエチレン
組成物の溶液 100重量部に、2,5-ジ- t-ブチル-p-クレ
ゾール（「ＢＨＴ」、住友化学工業（株）製） 0.125重
量部と、テトラキス〔メチレン-3-(3,5-ジ-t- ブチル-4
- ヒドロキシルフェニル)-プロピオネート〕メタン
（「イルガノックス1010」、チバガイギ−製）0.25重量
部とを酸化防止剤として加えた。この混合液を撹拌機付
のオートクレーブに充填し、 200℃で90分間撹拌して均
一な溶液を得た。 Example 1 Ultrahigh molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 20% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 66.7% by weight, melt index (MI, 190
℃, 2.16kg load) 2.0 g / 10min low density polyethylene (LD
15 parts by weight of raw material resin mixed with 13.3% by weight of PE) and 85 parts by weight of liquid paraffin (64 cst / 40 ° C.) were mixed to prepare a solution of a polyethylene composition. Next, to 100 parts by weight of this polyethylene composition solution, 0.125 parts by weight of 2,5-di-t-butyl-p-cresol (“BHT”, manufactured by Sumitomo Chemical Co., Ltd.) and tetrakis [methylene-3- (3,5-di-t-butyl-4
-Hydroxylphenyl) -propionate] methane ("Irganox 1010", manufactured by Ciba-Geigy) and 0.25 part by weight were added as an antioxidant. This mixed solution was filled in an autoclave equipped with a stirrer and stirred at 200 ° C. for 90 minutes to obtain a uniform solution.

【００５１】この溶液を直径45mmの押出機により、Ｔダ
イから押出し、冷却ロールで引取りながらゲル状シート
を成形した。This solution was extruded from a T-die by an extruder having a diameter of 45 mm, and a gel-like sheet was formed by taking it out with a cooling roll.

【００５２】得られたシートを二軸延伸機にセットし
て、温度 115℃、延伸速度 0.5ｍ／分で５×５倍に同時
二軸延伸を行った。得られた延伸膜を塩化メチレンで洗
浄して残留する流動パラフィンを抽出除去した後、100
℃で30秒熱セットすることによってポリエチレン微多孔
膜を得た。The obtained sheet was set in a biaxial stretching machine, and simultaneously biaxially stretched 5 × 5 times at a temperature of 115 ° C. and a stretching speed of 0.5 m / min. The drawn film thus obtained was washed with methylene chloride to extract and remove residual liquid paraffin.
A polyethylene microporous membrane was obtained by heat setting at ℃ for 30 seconds.

【００５３】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cut-off temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００５４】実施例２ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)20重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)66.7重量％と、メルトインデックス(MI、190
℃、2.16kg荷重) 1.5 ｇ/10分の線状低密度ポリエチレ
ン(LLDPE) 13.3重量％とを混合した原料樹脂を用いた以
外は実施例１と同様にしてポリエチレン微多孔膜を製造
した。 Example 2 Ultra high molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 20% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 66.7% by weight, melt index (MI, 190
A microporous polyethylene membrane was produced in the same manner as in Example 1 except that a raw material resin mixed with linear low density polyethylene (LLDPE) 13.3 wt% at 1.5 g / 10 min.

【００５５】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００５６】実施例３ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)20重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)77重量％と、メルトインデックス (MI、190 ℃、
2.16kg荷重) 2.0 ｇ/10 分の低密度ポリエチレン(LDPE)
３重量％とを混合した原料樹脂を用いた以外は実施例１
と同様にして、ポリエチレン微多孔膜を製造した。 Example 3 Ultra high molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 20% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 77% by weight, melt index (MI, 190 ℃,
2.16 kg load) 2.0 g / 10 min low density polyethylene (LDPE)
Example 1 except that a raw material resin mixed with 3% by weight was used.
A polyethylene microporous membrane was produced in the same manner as.

【００５７】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００５８】実施例４ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)20重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)77重量％と、メルトインデックス (MI、190 ℃、
2.16kg荷重) 1.5 ｇ/10 分の線状低密度ポリエチレン(L
LDPE) ３重量％とを混合した原料樹脂を用いた以外は実
施例１と同様にして、ポリエチレン微多孔膜を製造し
た。 Example 4 Ultra high molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 20% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 77% by weight, melt index (MI, 190 ℃,
2.16 kg load) 1.5 g / 10 min linear low density polyethylene (L
A polyethylene microporous membrane was produced in the same manner as in Example 1 except that a raw material resin mixed with 3% by weight of LDPE) was used.

【００５９】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cut-off temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００６０】比較例１ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)13重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)87重量％とを混合した原料樹脂15重量部と、流動
パラフィン（64cst/40℃）85重量部とを混合し、ポリエ
チレン組成物の溶液を調製した。次にこのポリエチレン
組成物の溶液 100重量部に、2,5-ジ- t-ブチル-p- クレ
ゾール（「ＢＨＴ」、住友化学工業（株）製） 0.125重
量部と、テトラキス〔メチレン-3-(3,5-ジ-t- ブチル-4
- ヒドロキシルフェニル)-プロピオネート〕メタン
（「イルガノックス1010」、チバガイギ−製）0.25重量
部とを酸化防止剤として加えた。この混合液を撹拌機付
のオートクレーブに充填し、 200℃で90分間撹拌して均
一な溶液を得た。 Comparative Example 1 Ultrahigh molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 13% by weight, 3.9 × 10 5 high density polyethylene
15 parts by weight of a raw material resin mixed with 87% by weight of (HDPE) and 85 parts by weight of liquid paraffin (64 cst / 40 ° C.) were mixed to prepare a solution of a polyethylene composition. Next, to 100 parts by weight of this polyethylene composition solution, 0.125 parts by weight of 2,5-di-t-butyl-p-cresol (“BHT”, manufactured by Sumitomo Chemical Co., Ltd.) and tetrakis [methylene-3- (3,5-di-t-butyl-4
-Hydroxylphenyl) -propionate] methane ("Irganox 1010", manufactured by Ciba-Geigy) and 0.25 part by weight were added as an antioxidant. This mixed solution was filled in an autoclave equipped with a stirrer and stirred at 200 ° C. for 90 minutes to obtain a uniform solution.

【００６１】この溶液を直径45mmの押出機により、Ｔダ
イから押出し、冷却ロールで引取りながらゲル状シート
を成形した。This solution was extruded from a T-die with an extruder having a diameter of 45 mm, and a gel-like sheet was formed while being taken up by a cooling roll.

【００６２】得られたシートを二軸延伸機にセットし
て、温度 115℃、延伸速度 0.5ｍ／分で５×５倍に同時
二軸延伸を行った。得られた延伸膜を塩化メチレンで洗
浄して残留する流動パラフィンを抽出除去した後、115
℃で30秒熱セットすることによってポリエチレン微多孔
膜を得た。The obtained sheet was set in a biaxial stretching machine and simultaneously biaxially stretched 5 × 5 times at a temperature of 115 ° C. and a stretching speed of 0.5 m / min. The drawn film thus obtained was washed with methylene chloride to extract and remove residual liquid paraffin.
A polyethylene microporous membrane was obtained by heat setting at ℃ for 30 seconds.

【００６３】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００６４】比較例２ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)10重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)55重量％と、メルトインデックス (MI、190 ℃、
2.16kg荷重) 2.0 ｇ/10 分の低密度ポリエチレン(LDPE)
35重量％とを混合した原料樹脂を用いた以外は実施例１
と同様にして、ポリエチレン微多孔膜を製造した。 Comparative Example 2 Ultrahigh molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 10% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 55% by weight, melt index (MI, 190 ℃,
2.16 kg load) 2.0 g / 10 min low density polyethylene (LDPE)
Example 1 except that a raw material resin mixed with 35% by weight was used
A polyethylene microporous membrane was produced in the same manner as.

【００６５】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００６６】比較例３ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)10重量％と、3.9 ×105 の高密度ポリエチレン
(HDPE)55重量％と、メルトインデックス (MI、190 ℃、
2.16kg荷重) 1.5 ｇ/10 分の線状低密度ポリエチレン(L
LDPE) 35重量％とを混合した原料樹脂を用いた以外は実
施例１と同様にして、ポリエチレン微多孔膜を製造し
た。 Comparative Example 3 Ultra high molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 10% by weight, 3.9 × 10 5 high density polyethylene
(HDPE) 55% by weight, melt index (MI, 190 ℃,
2.16 kg load) 1.5 g / 10 min linear low density polyethylene (L
A microporous polyethylene membrane was produced in the same manner as in Example 1 except that a raw material resin mixed with 35% by weight of LDPE) was used.

【００６７】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第１表に、またポリエチレン
微多孔膜の物性を第２表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. The composition and production conditions of the polyethylene microporous membrane are shown in Table 1, and the physical properties of the polyethylene microporous membrane are shown in Table 2.

【００６８】 第 １ 表組成 (重量％) 実施例１ 実施例２ 実施例３ 実施例４ ＵＨＭＷＰＥ 20 20 20 20 ＨＤＰＥ 66.7 66.7 77 77 ＬＤＰＥ 13.3 − ３ − ＬＬＤＰＥ − 13.3 − ３ 製造条件 延伸温度（℃） 115 115 115 115 熱セット温度（℃） 100 100 100 100 Table 1 Composition (wt%) Example 1 Example 2 Example 3 Example 4 UHMWPE 20 20 20 20 HDPE 66.7 66.7 77 77 LDPE 13.3-3-LLDPE-13.3-3 Manufacturing conditions Stretching temperature (° C) 115 115 115 115 Heat set temperature (℃) 100 100 100 100

【００６９】 第 １ 表 (続 き)組成 (重量％) 比較例１ 比較例２ 比較例３ ＵＨＭＷＰＥ 13 10 10 ＨＤＰＥ 87 55 55 ＬＤＰＥ − 35 − ＬＬＤＰＥ − − 35製造条件 延伸温度（℃） 115 115 115 熱セット温度（℃） 115 100 100Table 1 (continued) Composition (wt%) Comparative Example 1 Comparative Example 2 Comparative Example 3 UHMWPE 13 10 10 HDPE 87 55 55 LDPE-35-LLDPE--35 Manufacturing conditions Stretching temperature (° C) 115 115 115 Heat set temperature (℃) 115 100 100

【００７０】 第 ２ 表 特 性 実施例１ 実施例２ 実施例３ 実施例４ 膜厚(1) 25 25 25 25 空孔率(2) 50 60 55 50 平均貫通孔径(3) 0.025 0.025 0.03 0.03 引張破断強度(4) MD 800 800 880 920 TD 640 600 680 720 透気度(5) 952 612 780 580 透過性遮断温度(6) 115 120 120 125 実効抵抗(7) 2.21 2.15 2.18 2.12 [0070] Table 2 Characteristics Example 1 Example 2 Example 3 Example 4 thickness (1) 25 25 25 25 Porosity (2) 50 60 55 50 Average penetration pore diameter (3) 0.025 0.025 0.03 0.03 Tensile Breaking strength (4) MD 800 800 880 920 TD 640 600 680 720 Air permeability (5) 952 612 780 580 Permeability cutoff temperature (6) 115 120 120 125 Effective resistance (7) 2.21 2.15 2.18 2.12

【００７１】 [0071]

【００７２】注）＊：微多孔化していなかった。 (1)：単位はμｍ。 (2)：単位は％。 (3)：単位はμｍ。 (4)：単位は kg/cm2 で、長手方向（MD）と幅方向(TD)
について表示。 (5)：単位はsec/100cc 。 (6)：単位は℃。 (7)：単位はΩ・cm2 Note) *: It was not microporous. (1): Unit is μm. (2): The unit is%. (3): Unit is μm. (4): Unit is kg / cm 2 , longitudinal direction (MD) and width direction (TD)
Display about. (5): The unit is sec / 100cc. (6): Unit is ° C. (7): Unit is Ω · cm 2

【００７３】実施例５ 重量平均分子量が 2.0×106 の超高分子量ポリエチレン
(UHMWPE)50重量％と、メルトインデックス (MI、190
℃、2.16kg荷重) 2.0 ｇ/10 分の低密度ポリエチレン(L
DPE)50重量％とを混合した原料樹脂15重量部と、流動パ
ラフィン（64cst/40℃）85重量部とを混合し、ポリエチ
レン組成物の溶液を調製した。次にこのポリエチレン組
成物の溶液 100重量部に、2,5-ジ- t-ブチル-p- クレゾ
ール（「ＢＨＴ」、住友化学工業（株）製） 0.125重量
部と、テトラキス〔メチレン-3-(3,5-ジ-t- ブチル-4-
ヒドロキシルフェニル)-プロピオネート〕メタン（「イ
ルガノックス1010」、チバガイギ−製）0.25重量部とを
酸化防止剤として加えた。この混合液を撹拌機付のオー
トクレーブに充填し、 200℃で90分間撹拌して均一な溶
液を得た。 Example 5 Ultra high molecular weight polyethylene having a weight average molecular weight of 2.0 × 10 6.
(UHMWPE) 50% by weight and melt index (MI, 190
℃, 2.16kg load) 2.0 g / 10 min low density polyethylene (L
15 parts by weight of a raw material resin mixed with 50% by weight of DPE) and 85 parts by weight of liquid paraffin (64 cst / 40 ° C.) were mixed to prepare a solution of a polyethylene composition. Next, to 100 parts by weight of this polyethylene composition solution, 0.125 parts by weight of 2,5-di-t-butyl-p-cresol (“BHT”, manufactured by Sumitomo Chemical Co., Ltd.) and tetrakis [methylene-3- (3,5-di-t-butyl-4-
Hydroxylphenyl) -propionate] methane (“Irganox 1010”, manufactured by Ciba-Geigy) and 0.25 part by weight were added as an antioxidant. This mixed solution was filled in an autoclave equipped with a stirrer and stirred at 200 ° C. for 90 minutes to obtain a uniform solution.

【００７４】この溶液を直径45mmの押出機により、Ｔダ
イから押出し、冷却ロールで引取りながらゲル状シート
を成形した。This solution was extruded from a T-die by an extruder having a diameter of 45 mm, and a gel-like sheet was formed by taking it out with a cooling roll.

【００７５】得られたシートを二軸延伸機にセットし
て、温度 117℃、延伸速度 0.5ｍ／分で５×５倍に同時
二軸延伸を行った。得られた延伸膜を塩化メチレンで洗
浄して残留する流動パラフィンを抽出除去した後、100
℃で30秒熱セットすることによってポリエチレン微多孔
膜を得た。The obtained sheet was set in a biaxial stretching machine and simultaneously biaxially stretched 5 × 5 times at a temperature of 117 ° C. and a stretching speed of 0.5 m / min. The drawn film thus obtained was washed with methylene chloride to extract and remove residual liquid paraffin.
A polyethylene microporous membrane was obtained by heat setting at ℃ for 30 seconds.

【００７６】得られたポリエチレン微多孔膜の膜厚、引
張破断強度、空孔率、平均貫通孔径、透気度、透過性遮
断温度及び実効抵抗の測定を行った。ポリエチレン微多
孔膜の組成及び製造条件を第３表に、またポリエチレン
微多孔膜の物性を第４表に示す。The film thickness, tensile strength at break, porosity, average through-hole diameter, air permeability, permeability cutoff temperature and effective resistance of the obtained polyethylene microporous film were measured. Table 3 shows the composition and production conditions of the polyethylene microporous membrane, and Table 4 shows the physical properties of the polyethylene microporous membrane.

【００７７】実施例６ 実施例５において、低密度ポリエチレン（ＬＤＰＥ）の
代わりに、メルトインデックス（MI、190 ℃、2.16kg荷
重)1.5ｇ/10 分の線状低密度ポリエチレン（ＬＬＤＰ
Ｅ）を用いた以外は実施例５と同様にしてポリエチレン
微多孔膜を製造した。ポリエチレン微多孔膜の組成及び
製造条件を第３表に、またポリエチレン微多孔膜の物性
を第４表に示す。 Example 6 In Example 5, instead of low density polyethylene (LDPE), a linear low density polyethylene (LLDP) having a melt index (MI, 190 ° C., 2.16 kg load) of 1.5 g / 10 min was used.
A polyethylene microporous membrane was produced in the same manner as in Example 5 except that E) was used. Table 3 shows the composition and production conditions of the polyethylene microporous membrane, and Table 4 shows the physical properties of the polyethylene microporous membrane.

【００７８】 第 ３ 表組成 (重量％) 実施例５ 実施例６ ＵＨＭＷＰＥ 50 50 ＬＤＰＥ 50 − ＬＬＤＰＥ − 50製造条件 延伸温度（℃） 117 117 熱セット温度（℃） 100 100Table 3 Composition (wt%) Example 5 Example 6 UHMWPE 50 50 LDPE 50-LLDPE-50 Manufacturing conditions Stretching temperature (° C) 117 117 Heat setting temperature (° C) 100 100

【００７９】 [0079]

【００８０】注）＊：微多孔化していなかった。 (1)：単位はμｍ。 (2)：単位は％。 (3)：単位はμｍ。 (4)：単位は kg/cm2 で、長手方向（MD）と幅方向(TD)
について表示。 (5)：単位はsec/100cc 。 (6)：単位は℃。 (7)：単位はΩ・cm2 。Note) *: It was not microporous. (1): Unit is μm. (2): The unit is%. (3): Unit is μm. (4): Unit is kg / cm 2 , longitudinal direction (MD) and width direction (TD)
Display about. (5): The unit is sec / 100cc. (6): Unit is ° C. (7): The unit is Ω · cm 2 .

【００８１】本実施例から明らかなように、実施例１乃
至６のポリエチレン微多孔膜は、引張破断強度の値が良
好であり、透気度が大きく、しかも透過性遮断温度が13
5 ℃未満であった。また実施例１乃至６のポリエチレン
微多孔膜は、実効抵抗の値も十分に小さいものであり、
電池用セパレータとして好適なものであることがわか
る。As is clear from this example, the polyethylene microporous membranes of Examples 1 to 6 have good tensile rupture strength values, high air permeability, and a permeability cutoff temperature of 13%.
It was less than 5 ° C. Moreover, the polyethylene microporous membranes of Examples 1 to 6 have sufficiently small effective resistance values,
It can be seen that it is suitable as a battery separator.

【００８２】[0082]

【発明の効果】以上詳述したように、本発明の第一のポ
リエチレン微多孔膜は、超高分子ポリエチレンと、高密
度ポリエチレンと、低密度ポリエチレンとを含有する組
成物からなるので、透過性及び機械的強度に優れるとと
もに、低温で透過性が遮断する。As described in detail above, since the first polyethylene microporous membrane of the present invention is composed of a composition containing ultra high molecular weight polyethylene, high density polyethylene, and low density polyethylene, In addition to being excellent in mechanical strength, the permeability is cut off at low temperatures.

【００８３】また、本発明の第二のポリエチレン微多孔
膜は、超高分子量ポリエチレンと、低密度ポリエチレン
とからなる組成物からなるので、透過性能及び機械的強
度に優れるとともに、低温で透過性能が遮断する。Since the second polyethylene microporous membrane of the present invention is composed of a composition of ultrahigh molecular weight polyethylene and low density polyethylene, it has excellent permeation performance and mechanical strength as well as excellent permeation performance at low temperature. Cut off.

【００８４】このような本発明のポリエチレン微多孔膜
は、電池用セパレーター、電解コンデンサー用隔膜、光
シャッター、超精密濾過膜、限外濾過膜、各種フィルタ
ー、透湿防水衣料用多孔質膜等の各種用途に好適であ
り、特に電池用セパレーターに好適である。Such a polyethylene microporous membrane of the present invention is used as a separator for batteries, a diaphragm for electrolytic capacitors, an optical shutter, an ultraprecision filtration membrane, an ultrafiltration membrane, various filters, a porous membrane for moisture-permeable waterproof clothing and the like. It is suitable for various applications, and particularly suitable for battery separators.

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ２９Ｋ 23:00 4Ｆ 105:04 4Ｆ Ｂ２９Ｌ 7:00 4Ｆ Ｃ０８Ｌ 23:04 (72)発明者 恒吉 衛 埼玉県入間郡大井町西鶴ケ岡１−３−１ 東燃株式会社総合研究所内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification code Internal reference number FI Technical display location B29K 23:00 4F 105: 04 4F B29L 7:00 4F C08L 23:04 (72) Inventor Tsuneyoshi Mamoru 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Research Institute

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 重量平均分子量が７×105 以上の超高分
子量ポリエチレン１〜69重量％と、高密度ポリエチレン
98〜１重量％と、低密度ポリエチレン１〜30重量％とを
含有し、前記超高分子量ポリエチレンと、高密度ポリエ
チレンとを含有する成分の重量平均分子量／数平均分子
量が10〜300 である組成物からなり、厚さが 0.1〜50μ
ｍ、空孔率が35〜95％、平均貫通孔径が 0.001〜１μ
ｍ、引張破断強度が200kg/cm2 以上であり、透過性遮断
温度が135 ℃未満であることを特徴とするポリエチレン
微多孔膜。1. Ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more 1 to 69% by weight, and high density polyethylene
A composition containing 98-1% by weight and low-density polyethylene 1-30% by weight, and the weight-average molecular weight / number-average molecular weight of the component containing the ultrahigh molecular weight polyethylene and high-density polyethylene is 10-300. Made of objects and has a thickness of 0.1 to 50μ
m, porosity 35 to 95%, average through hole diameter 0.001 to 1μ
m, a tensile breaking strength of 200 kg / cm 2 or more, and a permeability cutoff temperature of less than 135 ° C. 【請求項２】 重量平均分子量が７×105 以上の超高分
子量ポリエチレン30〜90重量％と、低密度ポリエチレン
70〜10重量％とを含有する組成物からなり、厚さが 0.1
〜50μｍ、空孔率が35〜95％、平均貫通孔径が 0.001〜
１μｍ、引張破断強度が200kg/cm2 以上であり、透過性
遮断温度が135 ℃未満であることを特徴とするポリエチ
レン微多孔膜。2. Ultra-high molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more, 30 to 90% by weight, and low density polyethylene
70 to 10% by weight, and a thickness of 0.1
~ 50μm, porosity 35 ~ 95%, average through hole diameter 0.001 ~
A microporous polyethylene membrane having a 1 μm tensile strength of 200 kg / cm 2 or more and a permeability cutoff temperature of less than 135 ° C. 【請求項３】 重量平均分子量が７×105 以上の超高分
子量ポリエチレン１〜69重量％と、高密度ポリエチレン
98〜１重量％と、低密度ポリエチレン１〜30重量％とを
含有し、前記超高分子量ポリエチレンと、高密度ポリエ
チレンとを含有する成分の重量平均分子量／数平均分子
量が10〜300 である組成物10〜50重量％と、溶媒50〜90
重量％とからなる溶液を調製し、前記溶液をダイより押
出し、冷却してゲル状組成物を形成し、前記ゲル状組成
物を前記ポリエチレン組成物の融点＋10℃以下の温度で
延伸し、しかる後残存溶媒を除去することを特徴とする
ポリエチレン微多孔膜の製造方法。3. Ultra-high molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more 1 to 69% by weight, and high density polyethylene
A composition containing 98-1% by weight and low-density polyethylene 1-30% by weight, and the component containing the ultrahigh molecular weight polyethylene and the high-density polyethylene has a weight average molecular weight / number average molecular weight of 10-300. 10 to 50% by weight and solvent 50 to 90
% Of the polyethylene composition, and the solution is extruded from a die and cooled to form a gel composition, and the gel composition is stretched at a temperature not higher than the melting point of the polyethylene composition + 10 ° C., A method for producing a polyethylene microporous membrane, which comprises removing the residual solvent afterwards. 【請求項４】 重量平均分子量が７×105 以上の超高分
子量ポリエチレン30〜90重量％と、低密度ポリエチレン
70〜10重量％とを含有し、前記超高分子量ポリエチレン
と、高密度ポリエチレンとからなる組成物10〜50重量％
と、溶媒50〜90重量％とからなる溶液を調製し、前記溶
液をダイより押出し、冷却してゲル状組成物を形成し、
前記ゲル状組成物を前記ポリエチレン組成物の融点＋10
℃以下の温度で延伸し、しかる後残存溶媒を除去するこ
とを特徴とするポリエチレン微多孔膜の製造方法。4. Ultra-high molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more, 30 to 90% by weight, and low density polyethylene
70 to 10% by weight, and 10 to 50% by weight of a composition comprising the ultra high molecular weight polyethylene and high density polyethylene
A solution of 50 to 90% by weight of a solvent is prepared, the solution is extruded from a die and cooled to form a gel composition,
The melting point of the polyethylene composition +10
A method for producing a polyethylene microporous membrane, which comprises stretching at a temperature of ℃ or less, and then removing the residual solvent. 【請求項５】 請求項１又は２に記載のポリエチレン微
多孔膜からなることを特徴とする電池用セパレータ。5. A battery separator comprising the polyethylene microporous membrane according to claim 1 or 2.
JP20474991A 1991-07-19 1991-07-19 Polyethylene microporous membrane, method for producing the same, and battery separator using the same Expired - Fee Related JP2657434B2 (en)

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