JP4349793B2 - Conductive resin laminated film and method for producing the same - Google Patents
Conductive resin laminated film and method for producing the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、導電性に優れた熱可塑性樹脂からなる積層フィルムに係り、特に耐蝕性に優れた微細な炭素繊維を含有してなる低電気抵抗層を設けてなる導電性樹脂積層フィルム及びその製造方法に関する。
【０００２】
【従来の技術】
エレクトロニクス分野において、使用する高分子材料に求められる主要特性は製品や用途によって異なるが、成形性、耐熱性、耐久性、高導電性、耐蝕性、リサイクル性、電磁波遮蔽性等がある。通常、この分野で使用される高分子材料としては、エポキシ樹脂、フェノール樹脂等に代表される熱硬化性樹脂や、ポリフェニレンオキサイド、液晶ポリマー、ポリイミド、ポリカーボネート等に代表されるエンジニアリングプラスチックが挙げられる。
【０００３】
しかしながら、上記に挙げた各機能を総合的に具備した材料に対する要望は強いものがあるが、技術的に困難であり、価格面で不利となることが多いという問題があった。そのような要求特性のひとつに導電性があり、更に耐蝕性を兼ね備えた高分子材料が求められている。
【０００４】
このような特性を要求される製品として水系電解液を用いる電気二重層コンデンサーがある。水系電解液を用いる電気二重層コンデンサーにおいては、より高い出力電圧を得る目的で、複数のコンデンサーを、直列や並列にて接続し使用することがあるが、これらコンデンサーの複合体全体が有する内部抵抗が大きくなってしまい、低い出力電流しか得られない場合がある。このようなことから、個々のコンデンサーが有する内部抵抗を出来るだけ小さくすることが望まれている。
尚、個々のコンデンサーが有する内部抵抗は、水系電解液、分極性電極、集電体やこれらの界面などによって生じることが知られており、従来、例えば、集電体が有する体積抵抗値を小さくすることで、コンデンサーが有する内部抵抗を小さくすることなどが行われてきた。
また、水系電解液を用いる電気二重層コンデンサーは、電解液として２５〜５０％程度の硫酸水溶液を使用するため、集電体に対しては同時に耐酸性も要求されている。
【０００５】
上記集電体としてはフィルム中に含まれる導電性材料に金属を用いた導電性樹脂フィルムが知られているが、酸性環境下では導電性が不安定であるという欠点がある。導電性材料として耐蝕性に優れた貴金属を用いると極めて高価になるという問題があり、炭素系の導電材料は金属に比べて導電性が低く、充分な導電性が得られないという欠点がある。
【０００６】
そこで、熱可塑性樹脂と導電性カーボンを有機溶剤中に分散し、剥離可能なフィルム上にバーコーターで流延後、乾燥させて得られる導電性フィルムが知られている。
しかしながら、このような流延法によるフィルムでは、（１）フィルムに歪みが発生しやすい、（２）フィルムにピンホールが発生しやすい、（３）残留溶剤が残りやすい（４）厚膜フィルムにするのが難しい、（５）生産性が悪い等の問題がある。
【０００７】
また、特許文献１には、導電性に優れた微細な炭素繊維が導電性材料として示されている。しかしながら、このような微細な炭素繊維を樹脂に混合した場合、樹脂への分散性に劣り、充分な導電性が得られないという問題がある。
【０００７】
具体的には、特許文献２に示されている通り、樹脂８０％（重量比）に対して微細な炭素繊維２０％（重量比）を、ドライブレンドで混合した後、押出機にて成形したものは、体積抵抗値が１Ωｃｍ程度と大きく、充分な導電性が得られない。
【０００８】
【特許文献１】
特公平３−７７２８８号公報
【特許文献２】
特開平７−１０２１１２号公報
【０００９】
【発明が解決しようとする課題】
本発明の目的は、優れた導電性を有するとともに、耐酸性のある導電性樹脂積層フィルム及びその製造方法を提供することにある。
【００１０】
【課題を解決するための手段】
本発明は上述の問題点を解消でき、電気二重層コンデンサー用の集電体として好適に使用できる導電性樹脂積層フィルム及びその製造方法を見出したものであり、その要旨とするところは、導電性を有する基材層の少なくとも片面の最外層に、厚み方向への体積抵抗値が０．１〜１．０Ωｃｍの低電気抵抗層を設けてなる導電性樹脂積層フィルムであって、前記低電気抵抗層の厚み方向への体積抵抗値が、前記基材層の厚み方向への体積抵抗値の１／５以下であることを特徴とする導電性樹脂積層フィルムである。前記低電気抵抗層に含まれる導電剤が、繊維径が０．０８〜０．５μｍ、繊維長が０．１〜１００μｍである微細な炭素繊維であること、低電気抵抗層の厚みが１〜５０μｍの範囲であること、基材層に含まれる導電剤が、黒鉛粉、膨張黒鉛、カーボンブラック、カーボン繊維、カーボンナノファイバー、金属炭化物、金属窒化物、金属酸化物、金属繊維及び金属粉末から選ばれてなることが含まれている。
【００１１】
また、本発明は、微細な炭素繊維と熱可塑性樹脂を溶媒中に溶解、又は分散させてなる液状組成物を、支持体の平滑面に塗工し、乾燥又は硬化した後、得られる被膜を、導電性を有する基材層の少なくとも片面の最外層に低電気抵抗層として接合することを特徴とする導電性樹脂積層フィルムの製造方法にある。
上記導電性樹脂積層フィルムは、電気二重層コンデンサー用集電体に好適に使用できる。
【００１２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の導電性樹脂積層フィルムに使用する熱可塑性樹脂としては特に制限はない。例えば、エチレンを含む単独重合体又は共重合体等のポリオレフィン（ＰＯ）系樹脂又はポリオレフィン系エラストマー、環状ポリオレフィン等の非晶質ポリオレフィン樹脂（ＡＰＯ）、ポリスチレン（ＰＳ）、ＡＢＳ、ＳＢＳ等のポリスチレン系樹脂又はＳＥＢＳ等の水素添加されたスチレン系エラストマー、ポリ塩化ビニル（ＰＶＣ）樹脂、ポリ塩化ビニリデン（ＰＶＤＣ）樹脂、ポリメチルメタクリレート（ＰＭＭＡ）、共重合アクリル等のアクリル系樹脂、ポリエチレンテレフタレート（ＰＥＴ）等のポリエステル系樹脂、ナイロン６、ナイロン１２、共重合ナイロン等のポリアミド（ＰＡ）系樹脂、ポリビニルアルコール（ＰＶＡ）樹脂、エチレン−ビニルアルコール共重合体（ＥＶＯＨ）等のポリビニルアルコール系樹脂、ポリイミド（ＰＩ）樹脂、ポリエーテルイミド（ＰＥＩ）樹脂、ポリサルホン（ＰＳ）樹脂、ポリエーテルサルホン（ＰＥＳ）樹脂、ポリアミドイミド（ＰＡＩ）樹脂、ポリエーテルエーテルケトン（ＰＥＥＫ）樹脂、ポリカーボネート（ＰＣ）樹脂、ポリビニルブチラール（ＰＶＢ）樹脂、ポリアリレート（ＰＡＲ）樹脂、フッ化ビニリデン−四フッ化エチレン−六フッ化プロピレン共重合体（ＴＨＶ）、四フッ化エチレン−六フッ化プロピレン共重合体（ＦＥＰ）、フッ化ビニリデン（ＰＶＤＦ）、フッ化ビニル（ＰＶＦ）、等のフッ素系樹脂又はエラストマー、（メタ）アクリレート系樹脂などが挙げられる。
【００１３】
上記熱可塑性樹脂の中では、耐熱性、耐酸性に優れるポリオレフィン（ＰＯ）系樹脂又はポリオレフィン系エラストマー、ＳＥＢＳ等の水素添加されたスチレン系エラストマー及びフッ素系樹脂又はフッ素系エラストマーの使用が好ましい。
【００１４】
本発明の導電性樹脂積層フィルムは、基材層の少なくとも片側の最外層に特定の導電性を有する低電気抵抗層を有しており、低電気抵抗層の体積抵抗値を基材層より小さくすることで、被接触体との接触抵抗が大幅に低減できる。
特に本発明の導電性樹脂積層フィルムを電気二重層コンデンサー用集電体として使用する場合、被接触体は炭素系電極や外装ケース（ステンレス製ケース等）となるが、導電性樹脂積層フィルム中の低電気抵抗層の体積抵抗値を基材層より小さくすることで、被接触体との接触抵抗が低減でき、電気二重層コンデンサーの内部抵抗値を小さくすることができる。
【００１５】
低電気抵抗層の厚み方向への体積抵抗値は０．１〜１．０Ωｃｍの範囲とする必要があり、１．０Ωｃｍを超えると優れた導電性が得られ難い。低電気抵抗層の厚み方向への体積抵抗値は、基材層の厚み方向への体積抵抗値の１／５以下、好ましくは１／８以下にするのが良く、低電気抵抗層の厚み方向への体積抵抗値が、基材層の厚み方向への体積抵抗値の１／５より大きいと、被接触体との接触抵抗が大きくなり易い。
【００１６】
低電気抵抗層及び基材層の厚み方向への体積抵抗値は以下の方法で評価できる。
１． 測定装置
抵抗計：ＹＭＲ−３型（（株）山崎精機研究所社製）
負荷装置：ＹＳＲ−８型（（株）山崎精機研究所社製）
電極：真鍮製平板２枚（面積６．４５ｃｍ２、鏡面仕上げ、表面金メッキ）
２． 測定条件
方法：４端子法
印加電流：１０ｍＡ（交流、２８７Ｈｚ）
開放端子電圧：２０ｍＶピーク以下
荷重：１．８ＭＰａ（１８．６ｋｇｆ／ｃｍ２）
３．測定方法
図１に示した測定装置により測定した。
４． 体積抵抗算出方法
上記方法で測定された抵抗値Ｒ（Ω）と電極面積（６．４５ｃｍ２）及びサンプル厚みｔ（ｃｍ）から厚み方向への体積抵抗値は
厚み方向への体積抵抗値（Ωｃｍ）＝Ｒ×（６．４５ｃｍ２／ｔ）
で算出できる。
【００１７】
低電気抵抗層に含まれる導電剤には、耐蝕性と、導電性に優れる微細な炭素繊維が好適に使用できる。微細な炭素繊維の繊維径は０．０８〜０．５μｍ、好ましくは０．０８〜０．２μｍの範囲が良く、繊維長は０．１〜１００μｍ、好ましくは１〜５０μｍの範囲が導電性に優れており好ましい。
【００１８】
低電気抵抗層の熱可塑性樹脂と微細な炭素繊維の割合は、低電気抵抗層の厚み方向への体積抵抗値が基材層の厚み方向への体積抵抗値の１／５以下になるように適意決めればよいが、熱可塑性樹脂と微細な炭素繊維の体積比率が１５／８５〜８５／１５の範囲が好ましい。
【００１９】
低電気抵抗層の厚みは１〜５０μｍ、好ましくは、３〜２０μｍの範囲が良く、 低電気抵抗層の厚みが１μｍ未満では、厚みが薄いために低電気抵抗層にピンホールが発生しやすく、体積抵抗値の大きくなる部位ができやすい。また、低電気抵抗層の厚みが５０μｍを越えると、導電性性樹脂フィルムが脆くなるという問題が発生しやすい。また低電気抵抗層は基材層の片面でも、両面に設けてもよい。
【００２０】
基材層に含まれる導電剤は、天然黒鉛、熱分解黒鉛、キッシュ黒鉛等の黒鉛粉、酸性溶液に前述した黒鉛を浸漬させた後、加熱して膨張させた膨張黒鉛、ケッチェンブラック、アセチレンブラックやファーネス法等で作られたカーボンブラック、ＰＡＮ系、ピッチ系等のカーボン繊維、アーク放電法、レーザ蒸着法、気相成長法等で作られたカーボンナノファイバー、タングステンカーバイト、シリコンカーバイト、炭化ジルコニウム、炭化タンタル、炭化チタン、炭化ニオブ、炭化モリブデン、炭化バナジウムなどの金属炭化物、酸化チタン、酸化ルテニウム、酸化インジウムなどの金属酸化物、窒化クロム、窒化アルミニウム、窒化モリブデン、窒化ジルコニウム、窒化タンタル、窒化チタン、窒化ガリウム、窒化ニオブ、窒化バナジウム、窒化ホウ素などの金属窒化物、鉄繊維、銅繊維、ステンレス繊維などの金属繊維、チタン粉、ニッケル粉、錫紛、タンタル紛、ニオブ粉などの金属粉末が挙げられる。
上記導電剤の中でも特に耐酸性の優れる、カーボンブラックの使用が好ましい。
【００２１】
前記基材層の熱可塑性樹脂と導電剤との体積比率は、特に制限はないが、３０／７０〜９０／１０の範囲が良い。熱可塑性樹脂と導電剤との体積比率が３０／７０未満では、導電剤の割合が多いため、樹脂の流動性が悪く薄膜化が困難であり、また導電性樹脂積層フィルムが脆くなりやすい。また、熱可塑性樹脂と導電剤との体積比率が９０／１０を越えると導電剤の割合が少ないため、導電性に劣るという問題が発生しやすい。
基材層の製造方法は特に制限はないが、通常の押出成形法やロール成形法によればよい。
【００２２】
また、低電気抵抗層の製造方法は、微細な炭素繊維と熱可塑性樹脂を溶媒中に溶解、分散させてなる液状組成物を、支持体の平滑面に塗工し、乾燥又は硬化した後、予め形成しておいた基材層の片面又は両面に、基材層と低電気抵抗層塗工面が向き合うように配置し、熱圧着法等により、基材層と低電気抵抗層を一体化した後、支持体を剥離する方法が好ましい。
【００２３】
上記支持体としては、公知の各種フィルムを用いることができる。例えば、ポリエステル、ポリカーボネート、トリアセチルセルロース、セロハン、ポリアミド、芳香族ポリアミド、ポリイミド、ポリエーテルイミド、ポリフェニレンスルフィド、ポリスルホン、ポリエーテルスルホン、ポリプロピレン等のフィルムが挙げられる。なかでも、ポリプロピレンフィルムが、剥離容易性などの点から好ましい。
【００２４】
また、上記支持体の厚みは、５〜５００μｍ、好ましくは１０〜３００μｍの範囲であり、５μｍ未満では基材フィルムとして充分な強度が得られず皺が入りやすくなり、５００μｍを越えると腰が強くなりすぎて、取り扱いにくく作業性が悪いという問題がある。
【００２５】
本発明の製造方法によって形成された低電気抵抗層は、微細な炭素繊維が樹脂中に均一に分散できるため、微細な炭素繊維の割合が少なくても、優れた導電性が発現でき、更には微細な炭素繊維が導電性性樹脂フィルムの表面に露出するため、被接触体との接触抵抗を大幅に低減することができる。
【００２６】
本発明の導電性樹脂積層フィルムの用途は、導電性に優れ、特に被接触体との接触抵抗を大幅に低減することができるため、蓄電デバイスや発電機等の部材として使用した場合、その内部抵抗を格段に小さくすることができる。また、耐酸性にも優れるため、特に水系電解液を用いる電気二重層コンデンサーの集電体として使用できる。
【００２７】
以下、実施例について説明するが、本発明はこれに限定されるものではない。
＜基材層の作製＞
熱可塑性樹脂と導電剤を表１に記載した割合で２軸押出機（押出機温度２３０℃）にて混合した。
作成した混合物を、単軸押出機（押出機温度２３０℃）にて口金から押出して導電性を有する基材フィルムを作成した。
得られた基材フィルムの厚みはいずれも１００μｍであり、フィルムの厚さ方向への体積抵抗値を表１に示した。
なお、表１記載の熱可塑性樹脂及び導電剤は以下のものを使用した。
【００２８】
１．ポリオレフィン系エラストマー：
出光興産（株）製 「Ｔ３１０Ｅ」 比重０．８８
２．スチレン系エラストマー：
旭化成（株）製 「タフテックＨ１０４１」 比重０．９１
３．フッ素系エラストマー：
住友スリーエム（株）製 「ＴＨＶ２２０Ｇ」 比重２
４．カーボンブラック：
ライオン（株）製 「ケッチェンブラックＥＣ６００ＪＤ」 比重１．５
５．人造黒鉛粉：
昭和電工（株）製 「ＵＦＧ−３０」 比重２．２
６．炭化チタン：
（株）アライドマテリアル製 「チタンカーバイド」 比重４．９
【００２９】
＜低電気抵抗層Ａの作製＞
ＳＥＢＳ（旭化成（株）製 「タフテックＨ１０４１」 比重０．９１）と微細な炭素繊維（昭和電工（株）製 「気相法炭素繊維ＶＧＣＦ」 比重２）を体積比で６０／４０の割合で、固形分濃度８重量％になるように、それぞれＴＨＦ（テトラヒドロフラン）に分散し、分散液を作製した。
使用した微細な炭素繊維は、繊維径１５０ｎｍ、繊維長１０〜２０μｍ、嵩比重０．０３５ｇ／ｃｃ、真比重２．０ｇ／ｃｃのものを使用した。
この分散液を支持体（ポリプロピレンフィルム：厚み５０μｍ）上にバーコータ（「松尾産業製」＃７０番）で塗布し、８０℃で乾燥し、支持体−低電気抵抗層の複合体を得た。
得られた支持体−低電気抵抗層の複合体から低電気抵抗層Ａを剥離し、厚みと体積抵抗値を測定した結果、低電気抵抗層Ａの厚みは２０μｍであり、フィルムの厚さ方向への体積抵抗値は０．９４Ωｃｍであった。
【００３０】
＜低電気抵抗層Ｂの作製＞
フッ素系エラストマー（住友スリーエム（株）製 「ＴＨＶ２２０Ｇ」 比重２）と微細な炭素繊維（昭和電工（株）製 「気相法炭素繊維ＶＧＣＦ」 比重２）を体積比で６０／４０の割合で、固形分濃度８重量％になるように、それぞれＭＩＢＫ（メチルイソブチルケトン）に分散し、分散液を作製した。
使用した微細な炭素繊維は、繊維径１５０ｎｍ、繊維長１０〜２０μｍ、嵩比重０．０３５ｇ／ｃｃ、真比重２．０ｇ／ｃｃのものを使用した。
この分散液を支持体（ポリプロピレンフィルム：厚み５０μｍ）上にバーコータ（「松尾産業製」＃７０番）で塗布し、８０℃で乾燥し、支持体−低電気抵抗層複合体を得た。
得られた支持体−低電気抵抗層の複合体から低電気抵抗層Ｂを剥離し、厚みと体積抵抗値を測定した結果、低電気抵抗層Ｂの厚みは２０μｍであり、フィルムの厚さ方向への体積抵抗値は０．７３Ωｃｍであった。
【００３１】
［実施例１〜６］
＜導電性樹脂積層フィルムの作製＞
上記方法で得られた基材フィルムと、低電気抵抗層Ａ、Ｂを、表２記載の組み合わせで、低電気抵抗層／基材層／低電気抵抗層の順に配置し、熱プレスにて一体化し、導電性樹脂積層フィルムを作製した。
熱プレス法の条件は、加熱温度１４０℃、圧力４．９×１０６Ｐａ（５０ｋｇｆ／ｃｍ２）であった。
得られた導電性樹脂積層フィルムの厚みはいずれも１３０μｍであり、フィルムの厚さ方向への体積抵抗値は表２に示した。
【００３２】
【表１】
【表２】
表２に示す通り、本発明の方法にて作製した低電気抵抗層を有する導電性樹脂積層フィルムは、低電気抵抗層を設けていない表１の導電フィルムに比べ、フィルムの厚さ方向への体積抵抗値が、格段に小さく、導電性に優れることが分かる。
【００３６】
【発明の効果】
上述したように、本発明は、優れた導電性が発現する導電性樹脂積層フィルム及びその製造方法である。特に、フィルムの厚さ方向への体積抵抗値が小さく、耐蝕性に優れ、比較的低コストで生産可能なことから、電気二重層コンデンサー用集電体などへの利用性が大きい。
【００３７】
【図面の簡単な説明】
【図１】厚み方向への体積抵抗値を測定する装置の概略図。
【符号の説明】
１：真鍮製電極（表面金メッキ）
２：サンプル（導電シート）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminated film made of a thermoplastic resin having excellent conductivity, and in particular, a conductive resin laminated film provided with a low electrical resistance layer containing fine carbon fibers having excellent corrosion resistance, and production thereof. Regarding the method.
[0002]
[Prior art]
In the electronics field, the main characteristics required for the polymer material used vary depending on the product and application, but include moldability, heat resistance, durability, high conductivity, corrosion resistance, recyclability, electromagnetic wave shielding, and the like. Usually, examples of the polymer material used in this field include thermosetting resins typified by epoxy resins and phenol resins, and engineering plastics typified by polyphenylene oxide, liquid crystal polymer, polyimide, polycarbonate, and the like.
[0003]
However, although there is a strong demand for materials that comprehensively have the functions listed above, there is a problem that it is technically difficult and often disadvantageous in terms of price. One such required characteristic is electrical conductivity, and there is a need for a polymer material that also has corrosion resistance.
[0004]
There is an electric double layer capacitor using an aqueous electrolyte as a product requiring such characteristics. In an electric double layer capacitor using an aqueous electrolyte, a plurality of capacitors may be connected in series or in parallel for the purpose of obtaining a higher output voltage, but the internal resistance of the entire composite of these capacitors May become large, and only a low output current may be obtained. For this reason, it is desired to reduce the internal resistance of each capacitor as much as possible.
In addition, it is known that the internal resistance of each capacitor is caused by an aqueous electrolyte, a polarizable electrode, a current collector or an interface thereof, and conventionally, for example, the volume resistance value of the current collector is reduced. Thus, the internal resistance of the capacitor has been reduced.
In addition, since an electric double layer capacitor using an aqueous electrolyte uses a sulfuric acid aqueous solution of about 25 to 50% as the electrolyte, acid collectors are also required to have acid resistance at the same time.
[0005]
As the current collector, a conductive resin film using a metal as a conductive material contained in the film is known. However, there is a drawback that the conductivity is unstable in an acidic environment. When a noble metal excellent in corrosion resistance is used as the conductive material, there is a problem that it becomes very expensive, and the carbon-based conductive material has a drawback that the conductivity is lower than that of the metal and sufficient conductivity cannot be obtained.
[0006]
Therefore, a conductive film obtained by dispersing a thermoplastic resin and conductive carbon in an organic solvent, casting it on a peelable film with a bar coater, and drying it is known.
However, in the film by such a casting method, (1) the film is likely to be distorted, (2) pinholes are likely to be generated in the film, (3) the residual solvent is likely to remain (4) the thick film There are problems such as difficult to do and (5) poor productivity.
[0007]
Patent Document 1 discloses a fine carbon fiber excellent in conductivity as a conductive material. However, when such fine carbon fibers are mixed with the resin, there is a problem that the dispersibility in the resin is poor and sufficient conductivity cannot be obtained.
[0007]
Specifically, as shown in
[0008]
[Patent Document 1]
Japanese Patent Publication No. 3-77288 [Patent Document 2]
JP-A-7-102112 gazette
[Problems to be solved by the invention]
An object of the present invention is to provide a conductive resin laminated film having excellent conductivity and acid resistance and a method for producing the same.
[0010]
[Means for Solving the Problems]
The present invention has found a conductive resin laminated film that can solve the above-mentioned problems and can be suitably used as a current collector for an electric double layer capacitor, and a method for producing the same. A conductive resin laminated film in which a low electrical resistance layer having a volume resistance value in the thickness direction of 0.1 to 1.0 Ωcm is provided on at least one outermost layer of the base material layer having a low electrical resistance volume resistivity in the thickness direction of the layer, Ru conductive resin laminate film der, characterized in that it is 1/5 or less of the volume resistivity in the thickness direction of the base layer. Conductive agent contained in the prior SL low electric resistance layer, the fiber diameter 0.08～0.5Myuemu, it fiber length of the fine carbon fibers is 0.1 to 100 [mu] m, the thickness of the low resistance layer is 1 The conductive agent contained in the base layer is graphite powder, expanded graphite, carbon black, carbon fiber, carbon nanofiber, metal carbide, metal nitride, metal oxide, metal fiber, and metal powder. It is included to be selected from.
[0011]
The present invention also provides a coating obtained by applying a liquid composition prepared by dissolving or dispersing fine carbon fibers and a thermoplastic resin in a solvent to a smooth surface of a support and drying or curing. In the method for producing a conductive resin laminated film, a low electrical resistance layer is bonded to at least one outermost layer of the conductive base material layer.
The said conductive resin laminated | multilayer film can be used conveniently for the electrical power collector for electric double layer capacitors.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
There is no restriction | limiting in particular as a thermoplastic resin used for the conductive resin laminated film of this invention. For example, polyolefin (PO) resins such as homopolymers or copolymers containing ethylene or polyolefin elastomers, amorphous polyolefin resins (APO) such as cyclic polyolefins, polystyrenes such as polystyrene (PS), ABS, SBS, etc. Resin or hydrogenated styrene elastomer such as SEBS, polyvinyl chloride (PVC) resin, polyvinylidene chloride (PVDC) resin, polymethyl methacrylate (PMMA), acrylic resin such as copolymer acrylic, polyethylene terephthalate (PET) Polyester resins such as nylon 6, nylon 12, polyamide (PA) resins such as copolymer nylon, polyvinyl alcohol (PVA) resins, polyvinyl alcohol resins such as ethylene-vinyl alcohol copolymer (EVOH), poly Mido (PI) resin, polyetherimide (PEI) resin, polysulfone (PS) resin, polyethersulfone (PES) resin, polyamideimide (PAI) resin, polyetheretherketone (PEEK) resin, polycarbonate (PC) resin , Polyvinyl butyral (PVB) resin, polyarylate (PAR) resin, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (THV), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) , Fluororesins or elastomers such as vinylidene fluoride (PVDF) and vinyl fluoride (PVF), and (meth) acrylate resins.
[0013]
Among the thermoplastic resins, it is preferable to use a polyolefin (PO) resin or polyolefin elastomer excellent in heat resistance and acid resistance, a hydrogenated styrene elastomer such as SEBS, and a fluorine resin or fluorine elastomer.
[0014]
The conductive resin laminated film of the present invention has a low electrical resistance layer having specific conductivity in at least one outermost layer of the base material layer, and the volume resistance value of the low electrical resistance layer is smaller than that of the base material layer. By doing so, contact resistance with a to-be-contacted body can be reduced significantly.
In particular, when the conductive resin laminated film of the present invention is used as a current collector for an electric double layer capacitor, the contacted object is a carbon-based electrode or an outer case (such as a stainless steel case). By making the volume resistance value of the low electrical resistance layer smaller than that of the base material layer, the contact resistance with the contacted body can be reduced, and the internal resistance value of the electric double layer capacitor can be reduced.
[0015]
The volume resistance value in the thickness direction of the low electrical resistance layer must be in the range of 0.1 to 1.0 Ωcm, and if it exceeds 1.0 Ωcm, it is difficult to obtain excellent conductivity. The volume resistance value in the thickness direction of the low electrical resistance layer should be 1/5 or less, preferably 1/8 or less of the volume resistance value in the thickness direction of the base material layer. When the volume resistance value of the substrate is larger than 1/5 of the volume resistance value in the thickness direction of the base material layer, the contact resistance with the contacted body tends to increase.
[0016]
The volume resistance value in the thickness direction of the low electrical resistance layer and the base material layer can be evaluated by the following method.
1. Measuring device resistance meter: YMR-3 type (manufactured by Yamazaki Seiki Laboratory Co., Ltd.)
Load device: YSR-8 type (manufactured by Yamazaki Seiki Laboratory Co., Ltd.)
Electrode: 2 brass flat plates (area 6.45 cm 2 , mirror finish, surface gold plating)
2. Measurement condition method: 4-terminal method Applied current: 10 mA (AC, 287 Hz)
Open terminal voltage: 20 mV peak or less Load: 1.8 MPa (18.6 kgf / cm 2 )
3. Measurement method: Measured with the measuring apparatus shown in FIG.
4). Volume Resistance Calculation Method The resistance value R (Ω) and electrode area (6.45 cm 2 ) measured by the above method and the volume resistance value in the thickness direction from the sample thickness t (cm) are the volume resistance value (Ωcm in the thickness direction). ) = R × (6.45 cm 2 / t)
It can be calculated by
[0017]
As the conductive agent contained in the low electrical resistance layer, fine carbon fibers excellent in corrosion resistance and conductivity can be suitably used. The fine carbon fiber has a fiber diameter of 0.08 to 0.5 μm, preferably 0.08 to 0.2 μm, and a fiber length of 0.1 to 100 μm, preferably 1 to 50 μm. It is excellent and preferable.
[0018]
The ratio of the thermoplastic resin of the low electrical resistance layer to the fine carbon fibers is such that the volume resistance value in the thickness direction of the low electrical resistance layer is 1/5 or less of the volume resistance value in the thickness direction of the base material layer. The volume ratio between the thermoplastic resin and the fine carbon fibers is preferably in the range of 15/85 to 85/15.
[0019]
The thickness of the low electrical resistance layer is 1 to 50 μm, preferably 3 to 20 μm. If the thickness of the low electrical resistance layer is less than 1 μm, pinholes are likely to occur in the low electrical resistance layer because the thickness is small. It is easy to create a site where the volume resistance value increases. On the other hand, when the thickness of the low electrical resistance layer exceeds 50 μm, a problem that the conductive resin film becomes brittle is likely to occur. The low electrical resistance layer may be provided on one side or both sides of the base material layer.
[0020]
The conductive agent contained in the base material layer is graphite powder such as natural graphite, pyrolytic graphite, and quiche graphite, expanded graphite, ketjen black, and acetylene that are expanded by heating after immersing the aforementioned graphite in an acidic solution. Carbon black made by black or furnace method, carbon fiber made by PAN, pitch, etc., carbon nanofiber made by arc discharge method, laser deposition method, vapor phase growth method, tungsten carbide, silicon carbide Metal carbides such as zirconium carbide, tantalum carbide, titanium carbide, niobium carbide, molybdenum carbide, vanadium carbide, metal oxides such as titanium oxide, ruthenium oxide, indium oxide, chromium nitride, aluminum nitride, molybdenum nitride, zirconium nitride, nitride Tantalum, titanium nitride, gallium nitride, niobium nitride, vanadium nitride Metal nitrides such as boron nitride, iron fibers, copper fibers, metal fibers such as stainless steel fibers, titanium powder, nickel powder, Suzu紛, tantalum powder, and metal powder such as niobium powder.
Among the conductive agents, it is particularly preferable to use carbon black having excellent acid resistance.
[0021]
The volume ratio between the thermoplastic resin and the conductive agent of the base material layer is not particularly limited, but is preferably in the range of 30/70 to 90/10. When the volume ratio of the thermoplastic resin and the conductive agent is less than 30/70, the ratio of the conductive agent is large, so that the fluidity of the resin is poor and thinning is difficult, and the conductive resin laminated film tends to be brittle. In addition, when the volume ratio of the thermoplastic resin and the conductive agent exceeds 90/10, since the ratio of the conductive agent is small, the problem of poor conductivity is likely to occur.
Although the manufacturing method of a base material layer does not have a restriction | limiting in particular, What is necessary is just to follow a normal extrusion molding method and a roll molding method.
[0022]
In addition, the method for producing the low electrical resistance layer is obtained by applying a liquid composition obtained by dissolving and dispersing fine carbon fibers and a thermoplastic resin in a solvent to a smooth surface of a support, and drying or curing. Arrange the base material layer and the low electrical resistance layer on one or both sides of the base material layer so that the base material layer and the low electrical resistance layer coating face each other, and integrate the base material layer and the low electrical resistance layer by thermocompression bonding. Thereafter, a method of peeling the support is preferred.
[0023]
As the support, various known films can be used. Examples thereof include films of polyester, polycarbonate, triacetyl cellulose, cellophane, polyamide, aromatic polyamide, polyimide, polyetherimide, polyphenylene sulfide, polysulfone, polyethersulfone, polypropylene, and the like. Among these, a polypropylene film is preferable from the viewpoint of easy peeling.
[0024]
The thickness of the support is in the range of 5 to 500 μm, preferably 10 to 300 μm. If the thickness is less than 5 μm, sufficient strength cannot be obtained as a base film, and wrinkles easily occur. There is a problem that it becomes too difficult to handle and poor workability.
[0025]
The low electrical resistance layer formed by the production method of the present invention allows fine carbon fibers to be uniformly dispersed in the resin, so that even if the proportion of fine carbon fibers is small, excellent electrical conductivity can be expressed. Since fine carbon fibers are exposed on the surface of the conductive resin film, the contact resistance with the contacted body can be greatly reduced.
[0026]
The use of the conductive resin laminated film of the present invention is excellent in conductivity, and particularly can significantly reduce the contact resistance with a contacted object. The resistance can be significantly reduced. Moreover, since it is excellent also in acid resistance, it can be used especially as the electrical power collector of the electrical double layer capacitor | condenser which uses aqueous electrolyte solution.
[0027]
Hereinafter, although an example is described, the present invention is not limited to this.
<Preparation of base material layer>
The thermoplastic resin and the conductive agent were mixed in a ratio described in Table 1 with a twin screw extruder (extruder temperature 230 ° C.).
The prepared mixture was extruded from a die with a single screw extruder (extruder temperature 230 ° C.) to produce a conductive base film.
The thickness of the obtained base film was 100 μm, and the volume resistance value in the thickness direction of the film is shown in Table 1.
The following thermoplastic resins and conductive agents listed in Table 1 were used.
[0028]
1. Polyolefin elastomer:
Idemitsu Kosan Co., Ltd. “T310E” specific gravity 0.88
2. Styrene elastomer:
“Tough Tech H1041” manufactured by Asahi Kasei Co., Ltd. Specific gravity 0.91
3. Fluorine elastomer:
"THV220G" manufactured by Sumitomo 3M Limited
4). Carbon black:
“Ketjen Black EC600JD” made by Lion Co., Ltd., specific gravity 1.5
5. Artificial graphite powder:
"UFG-30" manufactured by Showa Denko KK Specific gravity 2.2
6). Titanium carbide:
"Titanium carbide" manufactured by Allied Material Co., Ltd.
[0029]
<Preparation of low electrical resistance layer A>
SEBS (Asahi Kasei Co., Ltd. “Tuftec H1041” specific gravity 0.91) and fine carbon fiber (Showa Denko Co., Ltd. “Gas phase method carbon fiber VGCF” specific gravity 2) at a volume ratio of 60/40, Dispersions were prepared in THF (tetrahydrofuran) so as to have a solid content concentration of 8% by weight to prepare dispersions.
The fine carbon fiber used had a fiber diameter of 150 nm, a fiber length of 10 to 20 μm, a bulk specific gravity of 0.035 g / cc, and a true specific gravity of 2.0 g / cc.
This dispersion was applied onto a support (polypropylene film: thickness 50 μm) with a bar coater (“Matsuo Sangyo” # 70) and dried at 80 ° C. to obtain a support-low electrical resistance layer composite.
As a result of peeling the low electrical resistance layer A from the obtained support-low electrical resistance layer composite and measuring the thickness and volume resistance value, the thickness of the low electrical resistance layer A is 20 μm, and the thickness direction of the film The volume resistance value was 0.94 Ωcm.
[0030]
<Preparation of low electrical resistance layer B>
Fluorine-based elastomer (Sumitomo 3M “THV220G” specific gravity 2) and fine carbon fiber (Showa Denko “Gas phase method carbon fiber VGCF” specific gravity 2) at a volume ratio of 60/40, Each was dispersed in MIBK (methyl isobutyl ketone) so as to have a solid content concentration of 8% by weight to prepare a dispersion.
The fine carbon fiber used had a fiber diameter of 150 nm, a fiber length of 10 to 20 μm, a bulk specific gravity of 0.035 g / cc, and a true specific gravity of 2.0 g / cc.
This dispersion was applied onto a support (polypropylene film: thickness 50 μm) with a bar coater (“Matsuo Sangyo” # 70) and dried at 80 ° C. to obtain a support-low electrical resistance layer composite.
The low electrical resistance layer B was peeled from the obtained support-low electrical resistance layer composite, and the thickness and volume resistance were measured. As a result, the thickness of the low electrical resistance layer B was 20 μm, and the thickness direction of the film The volume resistance value was 0.73 Ωcm.
[0031]
[Examples 1 to 6]
<Preparation of conductive resin laminated film>
The base film obtained by the above method and the low electrical resistance layers A and B are arranged in the order of low electrical resistance layer / base material layer / low electrical resistance layer in the combination shown in Table 2, and integrated by hot press. To produce a conductive resin laminated film.
The conditions of the hot press method were a heating temperature of 140 ° C. and a pressure of 4.9 × 10 6 Pa (50 kgf / cm 2 ).
The thicknesses of the obtained conductive resin laminated films were all 130 μm, and the volume resistance values in the thickness direction of the films are shown in Table 2.
[0032]
[Table 1]
[Table 2]
As shown in Table 2, the conductive resin laminated film having the low electrical resistance layer produced by the method of the present invention is more in the thickness direction of the film than the conductive film of Table 1 in which the low electrical resistance layer is not provided. It can be seen that the volume resistance value is remarkably small and the conductivity is excellent.
[0036]
【The invention's effect】
As described above, the present invention is a conductive resin laminated film exhibiting excellent conductivity and a method for producing the same. Particularly, since the volume resistance value in the thickness direction of the film is small, the corrosion resistance is excellent, and the film can be produced at a relatively low cost, it is highly applicable to a current collector for an electric double layer capacitor.
[0037]
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus for measuring a volume resistance value in a thickness direction.
[Explanation of symbols]
1: Brass electrode (surface gold plating)
2: Sample (conductive sheet)
Claims (5)
Priority Applications (10)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002341121A JP4349793B2 (en) | 2002-11-25 | 2002-11-25 | Conductive resin laminated film and method for producing the same |
| US10/519,339 US7514021B2 (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
| EP03760940A EP1553604A4 (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
| EP11002804A EP2367176A3 (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and manufacturing process therefor |
| CN 200710168157 CN101188150B (en) | 2002-06-24 | 2003-06-24 | Electric resin thin film, current collector and preparation method thereof |
| TW092117073A TWI241598B (en) | 2002-06-24 | 2003-06-24 | Electrical conducting resin film, collector and their manufacturing methods |
| PCT/JP2003/007961 WO2004001772A1 (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
| CNB038147963A CN100358056C (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
| AU2003244167A AU2003244167A1 (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
| KR10-2004-7020921A KR20050014875A (en) | 2002-06-24 | 2003-06-24 | Conductive resin film, collector and production methods therefore |
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| JP2002341121A JP4349793B2 (en) | 2002-11-25 | 2002-11-25 | Conductive resin laminated film and method for producing the same |
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| JP4349793B2 true JP4349793B2 (en) | 2009-10-21 |
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| WO2012133367A1 (en) | 2011-03-28 | 2012-10-04 | 東レ株式会社 | Conductive laminated body and touch panel |
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| JP4651638B2 (en) * | 2007-04-11 | 2011-03-16 | ヤマトエスロン株式会社 | Conductive resin laminate sheet and uncharged resin container |
| JP5291707B2 (en) | 2008-05-30 | 2013-09-18 | 三菱重工業株式会社 | Nanocarbon material manufacturing apparatus and method |
-
2002
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102039716A (en) * | 2010-11-02 | 2011-05-04 | 中科恒达石墨股份有限公司 | Method for manufacturing thermally and electrically conductive graphite ribbon |
| WO2012133367A1 (en) | 2011-03-28 | 2012-10-04 | 東レ株式会社 | Conductive laminated body and touch panel |
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| JP2007015109A (en) | 2007-01-25 |
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