JP2955418B2 - Manufacturing method of battery separator - Google Patents

Manufacturing method of battery separator

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Publication number
JP2955418B2
JP2955418B2 JP3352083A JP35208391A JP2955418B2 JP 2955418 B2 JP2955418 B2 JP 2955418B2 JP 3352083 A JP3352083 A JP 3352083A JP 35208391 A JP35208391 A JP 35208391A JP 2955418 B2 JP2955418 B2 JP 2955418B2
Authority
JP
Japan
Prior art keywords
molecular weight
battery
weight polyethylene
film
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.)
Expired - Lifetime
Application number
JP3352083A
Other languages
Japanese (ja)
Other versions
JPH05166502A (en
Inventor
一夫 山本
章夫 山口
陽三 長井
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
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Filing date
Publication date
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority to JP3352083A priority Critical patent/JP2955418B2/en
Publication of JPH05166502A publication Critical patent/JPH05166502A/en
Application granted granted Critical
Publication of JP2955418B2 publication Critical patent/JP2955418B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (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)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】この発明は、１次電池や２次電池
などの各種電池に用いられる電池用セパレ―タの製法に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a battery separator used for various batteries such as a primary battery and a secondary battery.

【０００２】[0002]

【従来の技術】電池用セパレ―タとしては、正負両極を
隔離するという本来の機能を有すると共に、電解液に対
する十分な耐性を備え、さらに電池の内部抵抗を増大さ
せることのない良好なイオン導電性をも備える必要があ
る。2. Description of the Related Art A separator for a battery has an original function of isolating the positive and negative electrodes, has a sufficient resistance to an electrolytic solution, and has a good ionic conductivity without increasing the internal resistance of the battery. It is also necessary to have sex.

【０００３】電池の種類は多いが、リチウムなどを負極
とする非水電解液電池は、高エネルギ―密度を有すると
共に、自己放電が少ないので、近年、大電流用電池とし
て注目されている。この非水電解液電池では、ジメチル
ホルムアミド、プロピレンカ―ボネ―ト、ブチロラクト
ンなどの非プロトン溶媒でかつ誘電率の高い液体に、Ｌ
ｉＰＦ6 、ＬｉＣｌＯ4 、ＬｉＢＦ4 などを電解質とし
て溶解したものを、電解液として用いている。この電解
液は電気伝導度が低いため、大電流を取り出すために、
正負極を構成する材料をセパレ―タを介して重ね合わせ
て渦巻き状に巻き、これを電池ケ―スに収納する方式を
とつている。Although there are many types of batteries, non-aqueous electrolyte batteries using lithium or the like as a negative electrode have attracted attention as high-current batteries in recent years because of their high energy density and low self-discharge. In this nonaqueous electrolyte battery, an aprotic solvent such as dimethylformamide, propylene carbonate, and butyrolactone, which has a high dielectric constant,
A solution in which iPF 6 , LiClO 4 , LiBF 4 or the like is dissolved as an electrolyte is used as an electrolytic solution. Since this electrolyte has low electric conductivity, in order to take out a large current,
In this method, the materials constituting the positive and negative electrodes are superimposed on each other via a separator and spirally wound, and the spirally wound material is housed in a battery case.

【０００４】このように、正負両極をセパレ―タを介し
て渦巻き状に巻き、これを電池ケ―スに収納するタイプ
の電池にあつては、用いるセパレ―タは、前記性能に加
えて、巻き込み作業や電池ケ―スへの収納作業時の機械
的ストレスに対して抵抗性を有し、破損しないことが、
生産効率（歩留り）の点から望ましい。As described above, in a battery of the type in which the positive and negative electrodes are spirally wound via a separator and housed in a battery case, the separator used in addition to the above-described performance has the following characteristics. It is resistant to mechanical stress during entanglement work and storage work in the battery case, and it is not damaged.
It is desirable from the viewpoint of production efficiency (yield).

【０００５】このような電池用セパレ―タとして、本発
明者らは、特開平２−２１５５９号公報や同２−２５１
５４５号公報などに記載されているような、超高分子量
ポリエチレンからなる微孔フイルムを、既に提案してい
る。この種の微孔フイルムは、一般に、素材ポリエチレ
ンを良溶媒に加熱溶解した均一溶液を調製し、これをフ
イルム成形に供したのち、貧溶媒に浸漬処理して多孔質
化し、最後に延伸処理する方法で作製される。As such a battery separator, the present inventors have disclosed in Japanese Patent Application Laid-Open Nos.
A microporous film made of ultra-high molecular weight polyethylene, as described in, for example, Japanese Patent Publication No. 545, 545 has already been proposed. This kind of microporous film is generally prepared by preparing a homogeneous solution prepared by heating and dissolving polyethylene as a raw material in a good solvent, subjecting it to film forming, immersing it in a poor solvent to make it porous, and finally stretching it. Produced by the method.

【０００６】[0006]

【発明が解決しようとする課題】しかるに、このような
超高分子量ポリエチレンからなる微孔フイルムは、電池
用セパレ―タとしての前記諸特性にすぐれ、また比較的
良好な機械的強度を示すものではあるが、巻き込み作業
や電池ケ―スへの収納作業などでの機械的ストレスに対
して必ずしも十分に耐えるものではなかつた。However, such a microporous film made of ultra-high molecular weight polyethylene is excellent in the above-mentioned characteristics as a battery separator, and does not exhibit relatively good mechanical strength. However, it is not always enough to withstand the mechanical stress in the winding operation and the storage operation in the battery case.

【０００７】この発明は、上記の事情に鑑み、超高分子
量ポリエチレンからなる微孔フイルムとして、電池用セ
パレ―タとしての諸特性にすぐれると共に、電池製造時
にかかる機械的ストレスに対して非常にすぐれた抵抗性
を示すものを提供することを目的としている。In view of the above circumstances, the present invention provides a microporous film made of ultra-high-molecular-weight polyethylene, which has excellent characteristics as a battery separator, and is extremely resistant to mechanical stress during battery production. It is intended to provide a material exhibiting excellent resistance.

【０００８】[0008]

【課題を解決するための手段】この発明者らは、上記目
的に対する鋭意検討の過程で、従来の微孔フイルムの作
製における素材ポリエチレンの加熱溶解工程では、ポリ
エチレンの融点以上の高い温度を適用して、いわゆる
“ままこ”状態のない均一な溶液を調製するようにして
いるが、この場合ポリエチレン分子鎖のからみ合いがと
きほぐれ、これが微孔フイルムの機械的強度を低下させ
る原因となることを知つた。Means for Solving the Problems In the course of intensive studies on the above-mentioned object, the present inventors have applied a high temperature higher than the melting point of polyethylene in the conventional heating and melting step of the raw material polyethylene in the production of microporous film. Therefore, a homogeneous solution without so-called "crankle" state is prepared, but in this case, the entanglement of the polyethylene molecular chains is sometimes loosened, and this may cause a decrease in the mechanical strength of the microporous film. I learned.

【０００９】そこで、素材ポリエチレンの加熱溶解工程
を改良し、素材ポリエチレンの融点より低い特定の温度
下で加熱溶解させることにより、電池用セパレ―タとし
ての諸特性を十分満足すると共に、電池製造時にかかる
機械的ストレスに対してすぐれた抵抗性を示す微孔フイ
ルムが得られることを知り、この発明に至つた。In view of the above, by improving the heating and melting process of the raw material polyethylene and heating and melting it at a specific temperature lower than the melting point of the raw material polyethylene, the characteristics as a battery separator can be sufficiently satisfied, and at the time of manufacturing the battery. The inventors have found that a microporous film exhibiting excellent resistance to such mechanical stress can be obtained, and have reached the present invention.

【００１０】すなわち、この発明は、粘度平均分子量
（粘度法によつて測定される平均分子量を意味する）が
１００万以上の超高分子量ポリエチレンを用いて、つぎ
の四つの工程； ａ）上記ポリエチレンを良溶媒に加熱溶解する工程であ
つて、その加熱溶解温度（Ｔ）が上記ポリエチレンの融
点（Ｍ）に対し（Ｍ−２０℃）≦Ｔ＜Ｍとなる温度範囲
で加熱溶解する工程 ｂ）上記工程で得た溶液を用いて加熱下でフイルム成形
する工程 ｃ）上記工程で得たフイルム状物を貧溶媒に浸漬処理す
る工程 ｄ）上記浸漬処理後のフイルム状物を延伸処理する工程 を含む工程により、上記ポリエチレンの微孔フイルムか
らなる電池用セパレ―タを得ることを特徴とする電池用
セパレ―タの製法に係るものである。That is, the present invention uses an ultrahigh molecular weight polyethylene having a viscosity average molecular weight (mean average molecular weight measured by a viscosity method) of 1,000,000 or more, and comprises the following four steps: Is dissolved in a good solvent by heating, and the heating and dissolving temperature (T) is in the temperature range of (M−20 ° C.) ≦ T <M with respect to the melting point (M) of the polyethylene. B) A step of forming a film under heating using the solution obtained in the above step c) a step of immersing the film obtained in the above step in a poor solvent d) a step of stretching the film after the above immersion The present invention relates to a method for producing a separator for a battery, characterized in that a separator for a battery comprising the above-mentioned polyethylene microporous film is obtained by the steps including the above.

【００１１】[0011]

【発明の構成・作用】この発明に用いられる超高分子量
ポリエチレンは、粘度平均分子量１００万以上、特に好
適には１５０万以上で通常３００万程度までのものであ
つて、市販品としては、三井化学工業社製の商品名ハイ
ゼツクスミリオン、ヘキスト社製の商品名ホスタレンＧ
ＵＲなどがある。この超高分子量ポリエチレンの融点
は、その平均分子量によつて異なるが、一般には、１３
４〜１３８℃の範囲の融点を有するものが好ましく用い
られる。The ultrahigh molecular weight polyethylene used in the present invention has a viscosity average molecular weight of 1,000,000 or more, particularly preferably 1.5 million or more and usually up to about 3,000,000. The name of the product is "Heizex Million" manufactured by Kagaku Kogyo Co., Ltd.
UR and the like. Although the melting point of this ultra-high molecular weight polyethylene varies depending on its average molecular weight, it is generally 13
Those having a melting point in the range of 4 to 138 ° C are preferably used.

【００１２】この発明におけるａ工程において、用いる
良溶媒は、超高分子量ポリエチレンを溶解または膨張さ
せうるものであればよく、たとえば、キシレン、デカリ
ン、ｏ−ジクロロベンゼン、トリクロロベンゼンなどの
１種または２種以上が用いられる。In the step a in the present invention, the good solvent to be used may be any one capable of dissolving or swelling ultra-high molecular weight polyethylene, for example, one or two of xylene, decalin, o-dichlorobenzene and trichlorobenzene. More than one species is used.

【００１３】この良溶媒と超高分子量ポリエチレンとの
混合比は、両者の合計量中に占める超高分子量ポリエチ
レンの割合が通常１〜２０重量％、特に好適には３〜１
０重量％となるようにするのがよい。超高分子量ポリエ
チレンの割合が過少であると機械的ストレスに対する耐
性が不十分となり、過多であるとｂ工程でのフイルム成
形が難しくなる。The mixing ratio of the good solvent and the ultrahigh molecular weight polyethylene is such that the proportion of the ultrahigh molecular weight polyethylene in the total amount of the two is usually 1 to 20% by weight, particularly preferably 3 to 1%.
The content is preferably set to 0% by weight. If the proportion of the ultrahigh molecular weight polyethylene is too small, the resistance to mechanical stress becomes insufficient, and if it is too large, film forming in the step b becomes difficult.

【００１４】良溶媒に超高分子量ポリエチレンを加熱溶
解させるには、まず両者を混合し、これを撹拌しながら
徐々に昇温して溶解させる方法が、一般的に採用され
る。その際の全所要時間は、約２〜１０時間程度であ
る。In order to heat and dissolve ultra-high molecular weight polyethylene in a good solvent, a method of mixing the two and then gradually increasing the temperature with stirring to dissolve the ultra-high molecular weight polyethylene is generally adopted. The total required time at that time is about 2 to 10 hours.

【００１５】このような加熱溶解において、最終的な加
熱温度（Ｔ）を、超高分子量ポリエチレンの融点（Ｍ）
に対し、（Ｍ−２０℃）≦Ｔ＜Ｍ、好ましくは（Ｍ−１
５℃）≦Ｔ≦（Ｍ−５℃）となる温度範囲とすることが
肝要である。（Ｍ−２０℃）よりも低い温度になると、
実質的な溶解または膨潤が行われず、ｂ工程でのフイル
ム成形が難しくなる。また、Ｍ以上、つまり超高分子量
ポリエチレンの融点以上の温度になると、機械的強度が
低下し、電池製造時の機械的ストレスに耐える微孔フイ
ルムが得られなくなる。In such heat melting, the final heating temperature (T) is determined by the melting point (M) of the ultrahigh molecular weight polyethylene.
(M-20 ° C.) ≦ T <M, preferably (M−1)
It is important that the temperature range be such that (5 ° C.) ≦ T ≦ (M−5 ° C.). (M-20 ° C)
Substantially no dissolution or swelling takes place, making film formation in step b difficult. On the other hand, if the temperature is higher than M, that is, higher than the melting point of the ultrahigh molecular weight polyethylene, the mechanical strength is reduced, and it is not possible to obtain a microporous film that can withstand the mechanical stress during battery production.

【００１６】この発明のｂ工程においては、上記の如く
して得られる溶液を用いて、通常１２０〜１６０℃の加
熱条件下でフイルム成形する。その際、Ｔダイ法、イン
フレ―シヨン法など公知の各種成膜技術を任意に採用可
能である。このようなフイルム成形を行つたのちの冷却
は、自然放置でもよいし、つぎのｃ工程で用いるような
貧溶媒により強制冷却させるようにしてもよい。In the step (b) of the present invention, a film is formed from the solution obtained as described above, usually under heating conditions of 120 to 160 ° C. At this time, various known film forming techniques such as a T-die method and an inflation method can be arbitrarily adopted. The cooling after such film forming may be left naturally or may be forcedly cooled with a poor solvent used in the next step c.

【００１７】この発明のｃ工程では、上記ｂ工程で得ら
れるフイルム状物を貧溶媒中に浸漬処理して、フイルム
中に含まれる前記良溶媒を洗浄除去するものであり、適
当な気孔率の微孔フイルムとするうえで重要な工程であ
る。ここで用いられる貧溶媒は、超高分子量ポリエチレ
ンを常温で溶解しないものであればよく、中でもアルコ
―ル類、特にメタノ―ルが好ましい。浸漬処理時間は、
常温で１秒以上、通常は５秒〜３０分間とするのがよ
い。In the step (c) of the present invention, the film obtained in the step (b) is immersed in a poor solvent to wash and remove the good solvent contained in the film. This is an important step in forming a microporous film. The poor solvent used here may be any solvent that does not dissolve ultra-high molecular weight polyethylene at room temperature, and among them, alcohols, particularly methanol are preferred. The immersion time is
It is preferable that the temperature be 1 second or more at room temperature, and usually 5 seconds to 30 minutes.

【００１８】この発明のｄ工程においては、上記ｃ工程
の浸漬処理後乾燥して得られるフイルム状物を、超高分
子量ポリエチレンの融点以下の温度、通常１０〜１３０
℃で延伸処理するものであり、この延伸処理によつて最
終的な気孔率やイオン導電性が決定される。このときの
延伸倍率は、通常１．２倍以上、好ましくは１．３〜６
倍となるようにするのがよい。また、延伸は通常一軸延
伸であるが、二軸延伸を行つてもよい。In the step (d) of the present invention, the film obtained by drying after the immersion treatment in the step (c) is treated at a temperature lower than the melting point of the ultrahigh molecular weight polyethylene, usually 10 to 130.
The porosity and ionic conductivity are finally determined by this stretching treatment. The stretching ratio at this time is usually 1.2 times or more, preferably 1.3 to 6 times.
It is better to double. The stretching is usually uniaxial stretching, but may be biaxial stretching.

【００１９】このようにして得られる超高分子量ポリエ
チレンからなる微孔フイルムは、厚さが通常５〜２００
μｍ、孔径が約０．１〜２０μｍ程度で、気孔率が一般
に２０〜９０％程度のものである。この微孔フイルムに
は、その一般特性を改良する目的で、酸化防止剤、難燃
剤、充てん剤などの各種添加剤を含ませるようにしても
よい。これらの添加剤は、前記ａ工程における良溶媒へ
の素材ポリエチレンの加熱溶解工程で任意に添加するこ
とが可能である。The microporous film made of the ultrahigh molecular weight polyethylene thus obtained usually has a thickness of 5 to 200.
μm, the pore size is about 0.1 to 20 μm, and the porosity is generally about 20 to 90%. The microporous film may contain various additives such as an antioxidant, a flame retardant, and a filler for the purpose of improving its general properties. These additives can be arbitrarily added in the step of heating and dissolving the raw material polyethylene in the good solvent in the step a.

【００２０】この発明では、上記の微孔フイルムを各種
電池の電池用セパレ―タとして用いるが、このセパレ―
タは、前記ｄ工程の延伸処理の前または後で架橋処理し
たものであつてもよいし、このような架橋処理を施して
ないものであつてもよい。また、上記延伸処理におい
て、超高分子量ポリエチレンの融点より１０〜４０℃低
い温度で、かつ線圧条件を０．０１〜１０kg／cm程度で
加熱、加圧延伸を行い、複数枚を積層化したものであつ
てもよい。In the present invention, the microporous film described above is used as a battery separator for various batteries.
The substrate may be one subjected to crosslinking treatment before or after the stretching treatment in the step d, or one not subjected to such crosslinking treatment. Further, in the stretching treatment, heating and pressure stretching were performed at a temperature lower by 10 to 40 ° C. than the melting point of the ultra-high molecular weight polyethylene at a linear pressure condition of about 0.01 to 10 kg / cm, and a plurality of sheets were laminated. It may be something.

【００２１】[0021]

【発明の効果】この発明は、超高分子量ポリエチレンか
らなる素材を良溶媒に対して特定の温度下で加熱溶解さ
せて、微孔フイルム化するものであるため、電池用セパ
レ―タとしての諸特性を満足すると共に、電池製造時の
機械的ストレスに対し十分に耐えうる機械的強度の良好
なセパレ―タを得ることができる。According to the present invention, a material made of ultra-high molecular weight polyethylene is heated and dissolved in a good solvent at a specific temperature to form a microporous film. It is possible to obtain a separator which satisfies the characteristics and has good mechanical strength enough to withstand the mechanical stress during the production of the battery.

【００２２】[0022]

【実施例】つぎに、この発明の実施例を記載して、より
具体的に説明する。Next, an embodiment of the present invention will be described in more detail.

【００２３】実施例１ ガラス容器に、キシレン１，０００ｇ、デカリン１，０
００ｇおよび粘度平均分子量３００万，融点１３６℃の
超高分子量ポリエチレンの微粉末１５０ｇを、投入し、
撹拌しながら１２５℃まで１℃／分の条件で温度上昇さ
せ、超高分子量ポリエチレンを溶解させた。EXAMPLE 1 In a glass container, 1,000 g of xylene and 1.0 g of decalin were added.
00 g and 150 g of ultra-high molecular weight polyethylene fine powder having a viscosity average molecular weight of 3,000,000 and a melting point of 136 ° C.
The temperature was increased to 125 ° C. at 1 ° C./min with stirring to dissolve the ultrahigh molecular weight polyethylene.

【００２４】この状態では、超高分子量ポリエチレンの
微粉末が良溶媒に膨潤され、微粉末の表面が溶解される
ことで微粉末同志が融着し、溶液の粘度は上がり、白濁
した状態になる。つぎに、撹拌を停止し、同温度で約２
時間保持した。これにより、微粉末の中央部まで良溶媒
が入り込み、溶液が完全に透明となつた。In this state, the fine powder of ultra-high molecular weight polyethylene is swollen in a good solvent and the surface of the fine powder is dissolved, whereby the fine powder is fused together, the viscosity of the solution increases, and the solution becomes cloudy. . Next, the stirring was stopped and at the same temperature for about 2 hours.
Hold for hours. As a result, the good solvent penetrated to the center of the fine powder, and the solution became completely transparent.

【００２５】このようにして得られた溶液を、１３５℃
に昇温したＴダイスを用いて、押出量１００ｇ／分で、
厚さ５０μｍのフイルム状物に成形し、メタノ―ルで１
分間冷却後、巻き取つた。つぎに、このフイルム状物を
メタノ―ル中に１０分間浸漬処理し、良溶媒を洗浄除去
したのち、乾燥した。最後に、この乾燥フイルムを半裁
し、延伸ラミネ―タで、温度１２０℃、線圧１．３kg／
cm、速度０．８ｍ／分、延伸倍率２倍の条件で、延伸と
同時に２枚を積層化した。The solution obtained in this way is heated at 135 ° C.
Using a T-die heated to an extrusion rate of 100 g / min,
It is formed into a film having a thickness of 50 μm, and
After cooling for minutes, it was wound up. Next, this film was immersed in methanol for 10 minutes to remove the good solvent, and then dried. Finally, the dried film was cut in half and stretched by a laminator at a temperature of 120 ° C. and a linear pressure of 1.3 kg / kg.
Under the conditions of cm, a speed of 0.8 m / min, and a stretching magnification of 2 times, two sheets were laminated simultaneously with the stretching.

【００２６】このようにして得られた超高分子量ポリエ
チレンからなる微孔フイルムは、厚さが２５μｍ、孔径
が約１μｍ、気孔率が６０％であつた。この微孔フイル
ムを、この発明の電池用セパレ―タとした。The microporous film made of ultra-high molecular weight polyethylene thus obtained had a thickness of 25 μm, a pore diameter of about 1 μm, and a porosity of 60%. This microporous film was used as the battery separator of the present invention.

【００２７】実施例２ ガラス容器に、キシレン１，０００ｇ、デカリン１，０
００ｇおよび粘度平均分子量６００万，融点１３８℃の
超高分子量ポリエチレンの微粉末１００ｇを、投入し、
撹拌しながら１３０℃まで１℃／分の条件で温度上昇さ
せ、超高分子量ポリエチレンを溶解させた。Example 2 In a glass container, 1,000 g of xylene and 1.0 g of decalin were added.
And 100 g of ultra-high-molecular-weight polyethylene fine powder having a viscosity average molecular weight of 6,000,000 and a melting point of 138 ° C.
The temperature was raised to 130 ° C. at 1 ° C./min with stirring to dissolve the ultrahigh molecular weight polyethylene.

【００２８】この状態では、超高分子量ポリエチレンの
微粉末が良溶媒に膨潤され、微粉末の表面が溶解される
ことで微粉末同志が融着し、溶液の粘度は上がり、白濁
した状態になる。つぎに、撹拌を停止し、同温度で約２
時間保持した。これにより、微粉末の中央部まで良溶媒
が入り込み、溶液が完全に透明となつた。In this state, the fine powder of ultra-high molecular weight polyethylene is swollen in a good solvent, and the surface of the fine powder is dissolved, whereby the fine powders fuse together, the viscosity of the solution increases, and the solution becomes cloudy. . Next, the stirring was stopped and at the same temperature for about 2 hours.
Hold for hours. As a result, the good solvent penetrated to the center of the fine powder, and the solution became completely transparent.

【００２９】このようにして得られた溶液を、１３５℃
に昇温したＴダイスを用いて、押出量１００ｇ／分で、
厚さ５０μｍのフイルム状物に成形し、メタノ―ルで１
分間冷却後、巻き取つた。つぎに、このフイルム状物を
メタノ―ル中に１０分間浸漬処理し、良溶媒を洗浄除去
したのち、乾燥した。最後に、この乾燥フイルムを半裁
し、延伸ラミネ―タで、温度１２０℃、線圧１．３kg／
cm、速度０．８ｍ／分、延伸倍率２倍の条件で、延伸と
同時に２枚を積層化した。The solution obtained in this way is heated at 135 ° C.
Using a T-die heated to an extrusion rate of 100 g / min,
It is formed into a film having a thickness of 50 μm, and
After cooling for minutes, it was wound up. Next, this film was immersed in methanol for 10 minutes to remove the good solvent, and then dried. Finally, the dried film was cut in half and stretched by a laminator at a temperature of 120 ° C. and a linear pressure of 1.3 kg / kg.
Under the conditions of cm, a speed of 0.8 m / min, and a stretching magnification of 2 times, two sheets were laminated simultaneously with the stretching.

【００３０】このようにして得られた超高分子量ポリエ
チレンからなる微孔フイルムは、厚さが２５μｍ、孔径
が約１μｍ、気孔率が５５％であつた。この微孔フイル
ムを、この発明の電池用セパレ―タとした。The microporous film made of the ultrahigh molecular weight polyethylene thus obtained had a thickness of 25 μm, a pore diameter of about 1 μm, and a porosity of 55%. This microporous film was used as the battery separator of the present invention.

【００３１】比較例１ 実施例１で用いた超高分子量ポリエチレンおよび良溶媒
を同重量混合し、加熱溶解工程において撹拌しながら、
１℃／分の条件で１５０℃まで昇温し、同温度で約１時
間保持させた。それ以外は、実施例１と同様にして、厚
さが２５μｍ、孔径が約１μｍ、気孔率が６５％の超高
分子量ポリエチレンからなる微孔フイルムを得、これを
比較用の電池用セパレ―タとした。COMPARATIVE EXAMPLE 1 The ultra-high molecular weight polyethylene used in Example 1 and a good solvent were mixed by the same weight and stirred in a heating and dissolving step.
The temperature was raised to 150 ° C. under the condition of 1 ° C./min, and maintained at the same temperature for about 1 hour. Otherwise, in the same manner as in Example 1, a microporous film made of ultrahigh molecular weight polyethylene having a thickness of 25 μm, a pore diameter of about 1 μm, and a porosity of 65% was obtained, and this was used as a battery separator for comparison. And

【００３２】比較例２ 実施例２で用いた超高分子量ポリエチレンおよび良溶媒
を同重量混合し、加熱溶解工程において撹拌しながら、
１℃／分の条件で１５５℃まで昇温し、同温度で約１時
間保持させた。それ以外は、実施例２と同様にして、厚
さが２５μｍ、孔径が約１μｍ、気孔率が６０％の超高
分子量ポリエチレンからなる微孔フイルムを得、これを
比較用の電池用セパレ―タとした。COMPARATIVE EXAMPLE 2 The ultrahigh molecular weight polyethylene used in Example 2 and a good solvent were mixed by the same weight, and the mixture was stirred while being heated and dissolved.
The temperature was raised to 155 ° C. under the condition of 1 ° C./min, and maintained at the same temperature for about 1 hour. Otherwise, in the same manner as in Example 2, a microporous film made of ultrahigh molecular weight polyethylene having a thickness of 25 μm, a pore diameter of about 1 μm, and a porosity of 60% was obtained, and this was used as a battery separator for comparison. And

【００３３】上記の実施例１，２および比較例１，２の
各電池用セパレ―タについて、つぎの要領で、電気抵抗
値および巻き込み不良率を調べた。これらの結果は、後
記の表１に示されるとおりであつた。With respect to the battery separators of Examples 1 and 2 and Comparative Examples 1 and 2, the electric resistance value and the entrapment defect rate were examined in the following manner. These results were as shown in Table 1 below.

【００３４】＜電気抵抗値の測定＞ＪＩＳ−Ｃ−２３１
３に準じ、電解液として、プロピレンカ―ボネ―トと１
・３−ジオキソランとを体積比１：１で混合し、これに
電解質としての過塩素酸リチウムを１モル／リツトル溶
解させてなるものを用い、各電池用セパレ―タの電気抵
抗値を測定した。測定は、各電池用セパレ―タの５個に
ついて行い、その平均値で示した。<Measurement of Electric Resistance Value> JIS-C-231
According to 3 above, propylene carbonate and 1
A mixture of 3-dioxolane at a volume ratio of 1: 1 and lithium perchlorate as an electrolyte dissolved therein at 1 mol / liter was used to measure the electric resistance of each battery separator. . The measurement was performed for five battery separators, and the average value was shown.

【００３５】＜巻き込み不良率＞正極として二酸化マン
ガンを主成分とする活物質を、負極としてリチウム金属
を用い、これらを各電池用セパレ―タを介して、渦巻き
状に巻きとり、この渦巻き体を電池ケ―スに収納して電
池を構成させる。電解液として、上記の電気抵抗値の測
定に用いたものと同じものを使用し、２５０Ｖの電圧を
電池の両電極間に印加し、電気抵抗が１０ＭΩ以下とな
るものを不良とした。測定は、各電池用セパレ―タの５
０個について行い、その不良個数を巻き込み不良率
（％）として表した。<Roll-in Failure Rate> An active material mainly composed of manganese dioxide is used as a positive electrode, and lithium metal is used as a negative electrode. It is stored in a battery case to form a battery. As the electrolytic solution, the same one as used in the above-described measurement of the electric resistance value was used, a voltage of 250 V was applied between both electrodes of the battery, and those having an electric resistance of 10 MΩ or less were regarded as defective. The measurement was performed for each battery separator.
The test was performed for 0 pieces, and the number of defective pieces was expressed as a wrap-in defective rate (%).

【００３６】[0036]

【表１】 [Table 1]

【００３７】上記表１の結果から明らかなように、この
発明の製法にて得られる実施例１，２の電池用セパレ―
タは、対応する比較例１，２のものと変わらない低い電
気抵抗値を示し、セパレ―タとしての性能にすぐれてお
り、しかも巻き込み不良率が対応する比較例１，２のも
のに比べて低くなつており、電池製造時における機械的
ストレスに対してすぐれた抵抗性を示すものであること
がわかる。As is clear from the results shown in Table 1, the battery separators of Examples 1 and 2 obtained by the method of the present invention.
The separator has a low electric resistance value that is the same as that of the corresponding Comparative Examples 1 and 2, has excellent performance as a separator, and has a higher entrainment defect rate than that of Comparative Examples 1 and 2. It can be seen that the resistance is low, indicating excellent resistance to mechanical stress during battery production.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−21559（ＪＰ，Ａ) 特開 平２−88649（ＪＰ，Ａ) 特開 平３−105851（ＪＰ，Ａ) 特開 平５−9332（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01M 2/16 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-21559 (JP, A) JP-A-2-88649 (JP, A) JP-A-3-105585 (JP, A) JP-A-5-205 9332 (JP, A) (58) Field surveyed (Int. Cl. 6 , DB name) H01M 2/16

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 粘度平均分子量が１００万以上の超高分
子量ポリエチレンを用いて、つぎの四つの工程； ａ）上記ポリエチレンを良溶媒に加熱溶解する工程であ
つて、その加熱溶解温度（Ｔ）が上記ポリエチレンの融
点（Ｍ）に対し（Ｍ−２０℃）≦Ｔ＜Ｍとなる温度範囲
で加熱溶解する工程 ｂ）上記工程で得た溶液を用いて加熱下でフイルム成形
する工程 ｃ）上記工程で得たフイルム状物を貧溶媒に浸漬処理す
る工程 ｄ）上記浸漬処理後のフイルム状物を延伸処理する工程 を含む工程により、上記ポリエチレンの微孔フイルムか
らなる電池用セパレ―タを得ることを特徴とする電池用
セパレ―タの製法。1. An ultra-high molecular weight polyethylene having a viscosity average molecular weight of 1,000,000 or more using the following four steps: a) a step of heating and dissolving the polyethylene in a good solvent; Is heated and melted in a temperature range that satisfies (M−20 ° C.) ≦ T <M with respect to the melting point (M) of the polyethylene. B) Step of forming a film under heating using the solution obtained in the above step. D) a step of dipping the film obtained in the step in a poor solvent; d) a step of stretching the film after the dipping to obtain a battery separator made of the polyethylene microporous film. A method for producing a battery separator.
JP3352083A 1991-12-12 1991-12-12 Manufacturing method of battery separator Expired - Lifetime JP2955418B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3352083A JP2955418B2 (en) 1991-12-12 1991-12-12 Manufacturing method of battery separator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3352083A JP2955418B2 (en) 1991-12-12 1991-12-12 Manufacturing method of battery separator

Publications (2)

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JPH05166502A JPH05166502A (en) 1993-07-02
JP2955418B2 true JP2955418B2 (en) 1999-10-04

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ID=18421669

Family Applications (1)

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Country Link
JP (1) JP2955418B2 (en)

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