JP4190768B2

JP4190768B2 - Polyacrylonitrile-based carbon fiber spun yarn fabric and method for producing the same

Info

Publication number: JP4190768B2
Application number: JP2002025809A
Authority: JP
Inventors: 賢司島崎; 慎太郎田中; 祐介高見
Original assignee: Toho Rayon Co Ltd
Current assignee: Toho Rayon Co Ltd
Priority date: 2002-02-01
Filing date: 2002-02-01
Publication date: 2008-12-03
Anticipated expiration: 2022-02-01
Also published as: JP2003227053A

Description

【０００１】
【発明の属する技術分野】
本発明は、耐熱性、断熱性に優れ、厚さが薄く且つ電気伝導性の良いポリアクリロニトリル（ＰＡＮ）系炭素繊維紡績糸織物、及びその製造方法に関する。このＰＡＮ系炭素繊維紡績糸織物は、高分子燃料電池用電極材等に応用される。
【０００２】
【従来の技術】
ＰＡＮ系炭素繊維紡績糸織物は、ＰＡＮ系炭素繊維をシート状に形成したものであって、耐熱性、断熱性に優れ、通電性があるので、電極材等に応用されている。特に、低目付で厚さの薄いシート状のＰＡＮ系炭素繊維紡績糸織物は、場所をとらず軽量であり、高分子燃料電池用電極材等の炭素繊維材料として有用な素材である。
【０００３】
炭素繊維紡績糸織物としては、従来よりＰＡＮ系酸化繊維紡績糸織物を炭素化したものがある。
【０００４】
炭素繊維紡績糸織物の通電性を高く保ちつつ（電気抵抗値を低く保ちつつ）、厚さの薄い炭素繊維紡績糸織物を得る為には、原料の酸化繊維紡績糸織物を予め圧縮処理する等の工程が必要となる。しかし、圧縮処理条件に付する場合、圧縮処理後、酸化繊維紡績糸織物の強度が低下する、炭素化時、強度が低下する及び炭素微粉末が発生し易い、並びに、処理コストがかかるなどの問題がある。
【０００５】
【発明が解決しようとする課題】
本発明者等は、解決すべき上記問題について鋭意検討した結果、繊維直径の異なるＰＡＮ系酸化繊維を炭素化処理する場合、細い繊維は太い繊維よりも大きく縮むことを知得した。また、細い繊維と太い繊維とを混合、紡績、製織した後、炭素化処理した場合、太い繊維の間に細い繊維が入り、得られる細い炭素繊維と太い炭素繊維とからなる炭素繊維紡績糸織物は緻密で厚さが薄く且つ電気伝導性の良いものになることを知得した。更に、繊維直径の異なるＰＡＮ系炭素繊維からなる上記炭素繊維紡績糸織物は、その製造工程において圧縮処理等の工程を必要とせず、そのため強度が高く保たれ、炭素微粉末が発生しにくく且つ処理コストがかからないことを知得し、本発明を完成するに至った。
【０００６】
従って、本発明の目的とするところは、上記問題を解決したＰＡＮ系炭素繊維紡績糸織物、及びその製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
上記の目的を達成する本発明は、以下に記載するものである。
【０００８】
〔１〕繊維直径ＤＣ_Aが１０〜２０μｍのポリアクリロニトリル系炭素繊維１００質量部と、繊維直径ＤＣ_Bのポリアクリロニトリル系炭素繊維５〜２５質量部とからなるポリアクリロニトリル系炭素繊維紡績糸織物であって、前記炭素繊維の直径比ＤＣ_B／ＤＣ_Aが０．４〜０．８であり、厚さが０．２〜０．５ｍｍであり、嵩密度が０．１５〜０．３５ｇ／ｃｍ³であるポリアクリロニトリル系炭素繊維紡績糸織物。
【０００９】
〔２〕ポリアクリロニトリル系炭素繊維紡績糸織物を構成する紡績糸が、繊維直径ＤＯ_Aのポリアクリロニトリル系炭素繊維と繊維直径ＤＯ_Bのポリアクリロニトリル系炭素繊維との紡績糸である〔１〕に記載のポリアクリロニトリル系炭素繊維紡績糸織物。
【００１０】
〔３〕厚さ方向の電気抵抗値が３．５ｍΩ以下である〔１〕に記載のポリアクリロニトリル系炭素繊維紡績糸織物。
【００１１】
〔４〕繊維直径ＤＯ_Aが１３〜２６μｍのポリアクリロニトリル系酸化繊維１００質量部と、前記酸化繊維に対するの直径比ＤＯ_B／ＤＯ_Aが０．４〜０．８である繊維直径ＤＯ_Bのポリアクリロニトリル系酸化繊維５〜２５質量部とからなるポリアクリロニトリル系酸化繊維紡績糸織物を炭素化させることを特徴とする、繊維直径ＤＣ_Aが１０〜２０μｍのポリアクリロニトリル系炭素繊維１００質量部と、繊維直径ＤＣ_Bのポリアクリロニトリル系炭素繊維５〜２５質量部とからなるポリアクリロニトリル系炭素繊維紡績糸織物であって、前記炭素繊維の直径比ＤＣ_B／ＤＣ_Aが０．４〜０．８であり、厚さが０．２〜０．５ｍｍであり、嵩密度が０．１５〜０．３５ｇ／ｃｍ³であるポリアクリロニトリル系炭素繊維紡績糸織物の製造方法。
【００１２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１３】
本発明のＰＡＮ系炭素繊維紡績糸織物は、繊維直径ＤＣ_Aが１０〜２０μｍのＰＡＮ系炭素繊維（炭素繊維Ａ）１００質量部と、繊維直径ＤＣ_BのＰＡＮ系炭素繊維（炭素繊維Ｂ）５〜２５質量部とが互いに混合されてなる。炭素繊維Ａと炭素繊維Ｂとの混合形態は１本の炭素繊維紡績糸に両繊維が混合していても、炭素繊維Ａからなる炭素繊維紡績糸と、炭素繊維Ｂからなる炭素繊維紡績糸とを用いて織物を形成しても良い。
【００１４】
炭素繊維Ａと炭素繊維Ｂとの質量比（ＷＣ_B／ＷＣ_A）が０．０５未満の場合は、炭素繊維紡績糸織物の嵩密度が０．１５ｇ／ｃｍ³より低くなって通電性が悪くなるなどの不具合を生ずるので好ましくない。ＷＣ_B／ＷＣ_Aが０．２５を超える場合は、炭素繊維紡績糸織物における炭素繊維Ａと炭素繊維Ｂとの分散性が悪くなる、並びに、紡績糸織物の強度が低下するなどの不具合を生ずるので好ましくない。
【００１５】
ＰＡＮ系炭素繊維紡績糸織物を構成する炭素繊維の直径比ＤＣ_B／ＤＣ_Aは０．４〜０．８である。炭素繊維の直径比ＤＣ_B／ＤＣ_Aが０．４未満の場合は、炭素繊維Ａと炭素繊維Ｂとの混合状態において繊維の分散ムラを生じて炭素繊維紡績糸織物の強度が低下するので好ましくない。炭素繊維の直径比ＤＣ_B／ＤＣ_Aが０．８を超える場合も、炭素繊維紡績糸織物の強度が低下するので好ましくない。
【００１６】
ＰＡＮ系炭素繊維紡績糸織物を構成する炭素繊維の繊維直径ＤＣ_Aは１０〜２０μｍである。繊維直径ＤＣ_Aが１０μｍ未満の場合は、炭素繊維紡績糸織物の強度が低下するので好ましくない。繊維直径ＤＣ_Aが２０μｍを超える場合は、紡績糸織物の加工性が悪いので好ましくない。
【００１７】
ＰＡＮ系炭素繊維紡績糸織物の厚さは０．２〜０．５ｍｍである。
【００１８】
ＰＡＮ系炭素繊維紡績糸織物の厚さが０．２ｍｍ未満の場合は、この炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性は高いが、炭素化時、強度が低下する及び炭素微粉末が発生しやすいなどの不具合を生ずるので好ましくない。
【００１９】
ＰＡＮ系炭素繊維紡績糸織物の厚さが０．５ｍｍを超える場合は、この炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性が低く、電池性能が低下するので好ましくない。
【００２０】
ＰＡＮ系炭素繊維紡績糸織物の嵩密度は０．１５〜０．３５ｇ／ｃｍ³である。
【００２１】
ＰＡＮ系炭素繊維紡績糸織物の嵩密度が０．１５ｇ／ｃｍ³未満の場合は、この炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性が低く、電池性能が低下するので好ましくない。
【００２２】
ＰＡＮ系炭素繊維紡績糸織物の嵩密度が０．３５ｇ／ｃｍ³を超える場合は、この炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性は高いが、炭素化時、強度が低下する及び炭素微粉末が発生しやすいなどの不具合を生ずるので好ましくない。
【００２３】
本発明のＰＡＮ系炭素繊維紡績糸織物の厚さ方向の電気抵抗値は、後述する測定方法により測定して得られる電気抵抗値で３．５ｍΩ以下が好ましく、通常は０．５〜３．５ｍΩである。
【００２４】
本発明のＰＡＮ系炭素繊維紡績糸織物は、種々の方法で製造でき、特に制限がない。
【００２５】
以下に好ましい製造方法の一例を示す。即ち、先ず繊維直径ＤＯ_Aが１３〜２６μｍのＰＡＮ系酸化繊維（酸化繊維Ａ）１００質量部と、前記酸化繊維Ａに対するの直径比ＤＯ_B／ＤＯ_Aが０．４〜０．８である繊維直径ＤＯ_BのＰＡＮ系酸化繊維（酸化繊維Ｂ）５〜２５質量部とを混合した後、紡績糸織物加工してＰＡＮ系酸化繊維紡績糸織物を得、このＰＡＮ系酸化繊維紡績糸織物を炭素化させることによって製造することができる。炭素化方法は従来公知の方法が採用できる。
【００２６】
酸化繊維Ａと酸化繊維Ｂとの質量比（ＷＯ_B／ＷＯ_A）が０．０５未満の場合は、酸化繊維紡績糸織物の嵩密度が０．１８ｇ／ｃｍ³より低くなる、並びに、酸化繊維紡績糸織物を炭素化して得られる炭素繊維紡績糸織物の嵩密度が０．１５ｇ／ｃｍ³より低くなって通電性が悪くなるなどの不具合を生ずるので好ましくない。ＷＯ_B／ＷＯ_Aが０．２５を超える場合は、酸化繊維Ａと酸化繊維Ｂとの分散性が悪く、カーディング加工、精紡加工、及び製織加工、即ち紡績糸織物加工、並びに、炭素化が難しくなるので好ましくない。
【００２７】
なお、この製造方法においては、炭素繊維Ａは酸化繊維Ａに由来し、炭素繊維Ｂは酸化繊維Ｂに由来しているので、酸化繊維Ａの比重と酸化繊維Ｂの比重とがほぼ同じ場合、酸化繊維Ａと酸化繊維Ｂとの質量比（ＷＯ_B／ＷＯ_A）の値は、炭素繊維Ａと炭素繊維Ｂとの質量比（ＷＣ_B／ＷＣ_A）とほぼ同じ値である。
【００２８】
酸化繊維の直径比ＤＯ_B／ＤＯ_Aが０．４未満の場合は、酸化繊維Ａと酸化繊維Ｂとの混合時、繊維の分散ムラを生じて酸化繊維紡績糸織物の強度が低下する、並びに、炭素化時、紡績糸織物が切断されやすい及び炭素微粉末が発生しやすいなどの不具合を生ずるので好ましくない。酸化繊維の直径比ＤＯ_B／ＤＯ_Aが０．８を超える場合は、酸化繊維Ａと酸化繊維Ｂとの混合後のカーディング中にスライバー切れを生じやすい、酸化繊維紡績糸織物の嵩密度が０．１８ｇ／ｃｍ³より低くなる、並びに、酸化繊維紡績糸織物を炭素化して得られる炭素繊維紡績糸織物の嵩密度が０．１５ｇ／ｃｍ³より低くなって通電性が悪くなるなどの不具合を生ずるので好ましくない。
【００２９】
繊維直径ＤＯ_Aが１３μｍ未満の場合は、酸化繊維紡績糸織物を炭素化して得られる炭素繊維紡績糸織物の強度が低下するので好ましくない。繊維直径ＤＯ_Aが２６μｍを超える場合は、酸化繊維Ａと酸化繊維Ｂとを混合した後、カーディングしてスライバーを得、このスライバーを精紡加工、製織加工して中間原料の酸化繊維紡績糸織物を得る際、カーディング加工性、精紡加工性、製織加工性が低下するので好ましくない。
【００３０】
上記ＰＡＮ系酸化繊維紡績糸織物は、酸化繊維の直径比ＤＯ_B／ＤＯ_Aが０．４〜０．８の関係にある酸化繊維Ａと酸化繊維Ｂとを前記質量割合で分散させた後、カーディングしてスライバーを得、このスライバーを精紡加工して紡績糸を得、この紡績糸をシート状に製織加工することによって製造することができる。これらの紡績糸織物加工方法は従来公知の方法が適宜採用できる。
【００３１】
なお、ＰＡＮ系酸化繊維紡績糸織物の嵩密度は、０．１８〜０．４５ｇ／ｃｍ³が好ましい。
【００３２】
ＰＡＮ系酸化繊維紡績糸織物の嵩密度が０．１８ｇ／ｃｍ³未満の場合は、この酸化繊維紡績糸織物を炭素化して得られる炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性が低く、電池性能が低下するので好ましくない。
【００３３】
０．４５ｇ／ｃｍ³を超える嵩密度のＰＡＮ系酸化繊維紡績糸織物を得るには、過度な圧縮処理条件に付する圧縮処理を必要とするため、圧縮処理後、酸化繊維紡績糸織物の強度が低下するので好ましくない。なお、この過度に圧縮処理したＰＡＮ系酸化繊維紡績糸織物を炭素化してＰＡＮ系酸化繊維紡績糸織物を得る場合、得られる炭素繊維紡績糸織物を高分子電解質型燃料電池用電極材とするとき、電極材の通電性は高いが、炭素化時、強度が低下する及び炭素微粉末が発生しやすいなどの不具合を生ずるので好ましくない。
【００３４】
【実施例】
本発明を以下の実施例及び比較例により具体的に説明する。
【００３５】
以下の実施例及び比較例の条件により酸化繊維紡績糸織物、及び炭素繊維紡績糸織物を作製した。原料酸化繊維、酸化繊維紡績糸織物、及び炭素繊維紡績糸織物の諸物性値を、以下の方法により測定した。
【００３６】
比重：液置換法（ＪＩＳＲ−７６０１、置換液：エチルアルコール）により測定した。
【００３７】
厚さ：直径３０ｍｍの円形圧板で２００ｇの荷重(2.8kPa)時の厚さを測定した。
【００３８】
目付：酸化繊維紡績糸織物又は炭素繊維紡績糸織物の寸法及び質量から、単位面積当たりの質量を算出した。
【００３９】
嵩密度：上記条件により測定した厚さ及び目付から算出した。
【００４０】
紡績糸織物を構成する繊維の直径、及びその含有量：図１の繊維直径測定方法の概略説明図に示すように、測定対象の紡績糸織物を５ｃｍ角にカットし、この５ｃｍ角カット紡績糸織物２を更に３ｍｍ間隔で短冊４にカットした。次いで短冊４をピンセットでほぐした後、２００ｍｌビーカー６に入れ、これに１体積％のエタノール水溶液を１５０ｍｌ添加し、繊維８をエタノール水溶液に分散させた。
【００４１】
この繊維分散液１０をスポイトで採取し、プレパラートに載せ、倍率２００倍で顕微鏡写真を撮った。この顕微鏡写真から、検体数ｎ＝１００について繊維直径を測定した。繊維直径の測定値は、μｍ単位で小数１桁まで求めた。
【００４２】
この繊維直径測定値について、横軸を繊維直径、縦軸を繊維の個数としてヒストグラムにまとめると、太い繊維のピークと、細い繊維のピークとが出現した。各ピークの±１０％の繊維直径における繊維の個数から、各繊維直径の平均値を算出し、測定対象が炭素繊維紡績糸織物の場合は、それぞれＤＣ_Aμｍ及びＤＣ_Bμｍとした。
【００４３】
細い繊維と太い繊維との含有量の質量比（ＷＣ_B／ＷＣ_A）は、（細い繊維の個数×ＤＣ_B ²）／（太い繊維の個数×ＤＣ_A ²）の式を用いて算出した。
【００４４】
電気抵抗値：２枚の５０ｍｍ角（厚さ１０ｍｍ）の金メッキした電極に炭素繊維紡績糸織物を圧力１ＭＰａで挟み、両電極間の電気抵抗値（Ｒ(ｍΩ)）を測定し、これをその厚さにおける抵抗値と表示した。
【００４５】
セル電圧：炭素繊維紡績糸織物を５０ｍｍ角にカットし、これに触媒（Ｐｔ−Ｒｕ）を０．３ｍｇ／ｃｍ²担持させて、高分子電解質型燃料電池電極材を得た。高分子電解質膜（ナフィオン１１７）の両側に、上記５０ｍｍ角にカットした電極材を接合してセルを構成し、温度８０℃、電流密度１．６０Ａ／ｃｍ²においてセル電圧を測定した。
【００４６】
実施例１
表１に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．９０ｄｔｅｘ、比重１．４０、繊維直径１０．０μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）２３質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．７１と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．２３と算出される。
【００４７】
上記スライバーを精紡し、４０番手双糸（ＰＡＮ系酸化繊維紡績糸(紡績糸番手：２／４０)）を作製した。この酸化繊維紡績糸を製織し、織り形態：平織、紡績糸打込み本数４０本／ｉｎ（４０本／(２．５４ｃｍ)）、目付１６０ｇ／ｍ²、厚さ０．４５ｍｍ、嵩密度が０．３６ｇ／ｃｍ³のＰＡＮ系酸化繊維紡績糸織物を得た。
【００４８】
このＰＡＮ系酸化繊維紡績糸織物を、窒素雰囲気下、処理温度１５００℃で２分間炭素化し、ＰＡＮ系炭素繊維紡績糸織物を得た。
【００４９】
得られたＰＡＮ系炭素繊維紡績糸織物は、表１に示すように目付が９７ｇ／ｍ²、厚さが０．４０ｍｍ、嵩密度が０．２４ｇ／ｃｍ³、電気抵抗値が２．１ｍΩ、セル電圧が０．７４Ｖであり、良好な物性の紡績糸織物であった。
【００５０】
このＰＡＮ系炭素繊維紡績糸織物において、原料酸化繊維Ａに由来する太い炭素繊維Ａの直径は１１．１μｍ（ＤＣ_A）、原料酸化繊維Ｂに由来する細い炭素繊維Ｂの直径は８．１μｍ（ＤＣ_B）であった。これらＤＣ_AとＤＣ_Bの値から繊維直径比ＤＣ_B／ＤＣ_Aの値は０．７３と算出される。また、炭素繊維Ａと炭素繊維Ｂとの質量比ＷＣ_B／ＷＣ_Aは０．２３であった。
【００５１】
実施例２
表１に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．７２ｄｔｅｘ、比重１．４０、繊維直径８．０μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）１０質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．５７と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．２５と算出される。
【００５２】
上記スライバーを精紡し、４０番手双糸（ＰＡＮ系酸化繊維紡績糸(紡績糸番手：２／４０)）を作製した。この酸化繊維紡績糸を製織し、織り形態：平織、紡績糸打込み本数４０本／ｉｎ（４０本／(２．５４ｃｍ)）、目付１６０ｇ／ｍ²、厚さ０．４７ｍｍ、嵩密度が０．３４ｇ／ｃｍ³のＰＡＮ系酸化繊維紡績糸織物を得た。
【００５３】
このＰＡＮ系酸化繊維紡績糸織物を、窒素雰囲気下、処理温度１５００℃で２分間炭素化し、ＰＡＮ系炭素繊維紡績糸織物を得た。
【００５４】
得られたＰＡＮ系炭素繊維紡績糸織物は、表１に示すように目付が８８ｇ／ｍ²、厚さが０．４５ｍｍ、嵩密度が０．２０ｇ／ｃｍ³、電気抵抗値が２．８ｍΩ、セル電圧が０．７０Ｖであり、良好な物性の紡績糸織物であった。
【００５５】
このＰＡＮ系炭素繊維紡績糸織物において、原料酸化繊維Ａに由来する太い炭素繊維Ａの直径は１０．５μｍ（ＤＣ_A）、原料酸化繊維Ｂに由来する細い炭素繊維Ｂの直径は６．５μｍ（ＤＣ_B）であった。これらＤＣ_AとＤＣ_Bの値から繊維直径比ＤＣ_B／ＤＣ_Aの値は０．６２と算出される。また、炭素繊維Ａと炭素繊維Ｂとの質量比ＷＣ_B／ＷＣ_Aは０．１０であった。
【００５６】
実施例３
表１に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．９０ｄｔｅｘ、比重１．４０、繊維直径１０．０μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）１５質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．７１と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．１５と算出される。
【００５７】
上記スライバーを精紡し、５５番手双糸（ＰＡＮ系酸化繊維紡績糸(紡績糸番手：２／５５)）を作製した。この酸化繊維紡績糸を製織し、織り形態：平織、紡績糸打込み本数５３本／ｉｎ（５３本／(２．５４ｃｍ)）、目付１４５ｇ／ｍ²、厚さ０．３９ｍｍ、嵩密度が０．３７ｇ／ｃｍ³のＰＡＮ系酸化繊維紡績糸織物を得た。
【００５８】
このＰＡＮ系酸化繊維紡績糸織物を、窒素雰囲気下、処理温度１５００℃で２分間炭素化し、ＰＡＮ系炭素繊維紡績糸織物を得た。
【００５９】
得られたＰＡＮ系炭素繊維紡績糸織物は、表１に示すように目付が８７ｇ／ｍ²、厚さが０．３５ｍｍ、嵩密度が０．２５ｇ／ｃｍ³、電気抵抗値が２．０ｍΩ、セル電圧が０．７５Ｖであり、良好な物性の紡績糸織物であった。
【００６０】
このＰＡＮ系炭素繊維紡績糸織物において、原料酸化繊維Ａに由来する太い炭素繊維Ａの直径は１１．０μｍ（ＤＣ_A）、原料酸化繊維Ｂに由来する細い炭素繊維Ｂの直径は８．０μｍ（ＤＣ_B）であった。これらＤＣ_AとＤＣ_Bの値から繊維直径比ＤＣ_B／ＤＣ_Aの値は０．７３と算出される。また、炭素繊維Ａと炭素繊維Ｂとの質量比ＷＣ_B／ＷＣ_Aは０．１５であった。
【００６１】
【表１】

【００６２】
比較例１
表２に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．９０ｄｔｅｘ、比重１．４０、繊維直径１０．０μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）４質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．７１と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．０５と算出される。
【００６３】
上記スライバーを精紡し、４０番手双糸（ＰＡＮ系酸化繊維紡績糸(紡績糸番手：２／４０)）を作製した。この酸化繊維紡績糸を製織し、織り形態：平織、紡績糸打込み本数４０本／ｉｎ（４０本／(２．５４ｃｍ)）、目付１６０ｇ／ｍ²、厚さ０．６０ｍｍ、嵩密度が０．２７ｇ／ｃｍ³のＰＡＮ系酸化繊維紡績糸織物を得た。
【００６４】
このＰＡＮ系酸化繊維紡績糸織物を、窒素雰囲気下、処理温度１５００℃で２分間炭素化し、ＰＡＮ系炭素繊維紡績糸織物を得た。
【００６５】
得られたＰＡＮ系炭素繊維紡績糸織物は、表１に示すように目付が８７ｇ／ｍ²、厚さが０．６１ｍｍ、嵩密度が０．１４ｇ／ｃｍ³、電気抵抗値が３．８ｍΩ、セル電圧が０．６７Ｖであり、良好な物性の紡績糸織物ではなかった。
【００６６】
このＰＡＮ系炭素繊維紡績糸織物において、原料酸化繊維Ａに由来する太い炭素繊維Ａの直径は１１．１μｍ（ＤＣ_A）、原料酸化繊維Ｂに由来する細い炭素繊維Ｂの直径は８．０μｍ（ＤＣ_B）であった。これらＤＣ_AとＤＣ_Bの値から繊維直径比ＤＣ_B／ＤＣ_Aの値は０．７２と算出される。また、炭素繊維Ａと炭素繊維Ｂとの質量比ＷＣ_B／ＷＣ_Aは０．０４であった。
【００６７】
比較例２
表２に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．７２ｄｔｅｘ、比重１．４０、繊維直径８．０μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）８４質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．５７と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．８４と算出される。
【００６８】
上記スライバーを精紡し、ＰＡＮ系酸化繊維紡績糸を作製しようとしたところ、この紡績時に糸切れが多発し紡績糸は得られなかった。
【００６９】
比較例３
表２に示すように、繊度２．０ｄｔｅｘ、比重１．３９、繊維直径１４．０μｍ（ＤＯ_A）のＰＡＮ系酸化繊維Ａのカットファイバー（カット長５１ｍｍ）１００質量部に、繊度０．４５ｄｔｅｘ、比重１．４０、繊維直径４．５μｍ（ＤＯ_B）のＰＡＮ系酸化繊維Ｂのカットファイバー（カット長５１ｍｍ）２０質量部を均一に混打綿機により混合した後、カーディングし、スライバーを得た。上記ＤＯ_AとＤＯ_Bの値から繊維直径比ＤＯ_B／ＤＯ_Aの値は０．３２と算出される。また、酸化繊維Ａと酸化繊維Ｂとの質量比ＷＯ_B／ＷＯ_Aは０．２０と算出される。
【００７０】
上記スライバーを精紡し、ＰＡＮ系酸化繊維紡績糸を作製しようとしたところ、この紡績時に糸切れが多発し紡績糸は得られなかった。
【００７１】
【表２】

【００７２】
【発明の効果】
本発明のＰＡＮ系炭素繊維紡績糸織物は、上記構成にしたので、薄く、低目付で、高強度で、嵩密度が高く、更に電気抵抗が低い。
【００７３】
本発明の細い炭素繊維と太い炭素繊維とからなるＰＡＮ系炭素繊維紡績糸織物の製造方法は、細い酸化繊維と太い酸化繊維とからなる中間原料のＰＡＮ系酸化繊維紡績糸織物を得、これを炭素化することによって得られる。この酸化繊維紡績糸織物を炭素化することにより、細い酸化繊維が大きく収縮し且つ太い繊維の間に細い繊維が入って紡績糸織物の高密度化が達成され通電性が高くなると共に、太い酸化繊維が炭素化して紡績糸織物の高強度化が達成される。
【００７４】
本発明の製造方法により製造する炭素繊維紡績糸織物は、低目付で厚さが薄いので、場所をとらず軽量であり且つ強度が高く、高分子燃料電池用電極材等の炭素繊維材料として有用な素材である。
【００７５】
更に、本発明のＰＡＮ系炭素繊維紡績糸織物を製造方法によれば、圧縮処理等の工程を必要とせず、また炭素微粉末が発生しにくいものである。
【図面の簡単な説明】
【図１】紡績糸織物を構成する繊維の直径及び含有量の測定方法を示す概略説明図である。
【符号の説明】
２５ｃｍ角にカットした紡績糸織物
４３ｍｍ間隔でカットした短冊
６２００ｍｌビーカー
８繊維
１０繊維分散液[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyacrylonitrile (PAN) -based carbon fiber spun yarn fabric excellent in heat resistance and heat insulation, thin in thickness and good in electrical conductivity, and a method for producing the same. This PAN-based carbon fiber spun yarn fabric is applied to electrode materials for polymer fuel cells.
[0002]
[Prior art]
The PAN-based carbon fiber spun yarn fabric is formed by forming a PAN-based carbon fiber into a sheet shape, has excellent heat resistance and heat insulation, and has electrical conductivity, and is therefore applied to electrode materials and the like. In particular, a sheet-like PAN-based carbon fiber spun yarn fabric having a low basis weight and a small thickness is light in weight and is useful as a carbon fiber material such as an electrode material for polymer fuel cells.
[0003]
As the carbon fiber spun yarn fabric, there is a conventional carbonized PAN-based oxidized fiber spun yarn fabric.
[0004]
In order to obtain a carbon fiber spun yarn fabric with a small thickness while keeping the electrical conductivity of the carbon fiber spun yarn fabric high (while keeping the electrical resistance value low), the raw material oxidized fiber spun yarn fabric is pre-compressed. This process is required. However, when subjected to compression treatment conditions, after compression treatment, the strength of the oxidized fiber spun yarn fabric is reduced, during carbonization, the strength is reduced and carbon fine powder is easily generated, and the processing cost is increased. There's a problem.
[0005]
[Problems to be solved by the invention]
As a result of intensive studies on the above-mentioned problems to be solved, the present inventors have found that when carbonized PAN-based oxidized fibers having different fiber diameters, thin fibers shrink more than thick fibers. In addition, when carbonized after mixing, spinning and weaving thin fibers and thick fibers, the thin fibers enter between the thick fibers, and the resulting carbon fiber spun yarn fabric consisting of thin carbon fibers and thick carbon fibers. Has been found to be dense, thin and have good electrical conductivity. Furthermore, the above-mentioned carbon fiber spun yarn woven fabric made of PAN-based carbon fibers having different fiber diameters does not require a step such as compression treatment in the production process, so that the strength is kept high, and carbon fine powder is hardly generated and treated. It was learned that there was no cost and the present invention was completed.
[0006]
Accordingly, an object of the present invention is to provide a PAN-based carbon fiber spun yarn fabric and a method for producing the same, which have solved the above problems.
[0007]
[Means for Solving the Problems]
The present invention which achieves the above object is described below.
[0008]
[1] _A polyacrylonitrile-based carbon fiber spun yarn woven fabric comprising 100 parts by mass of polyacrylonitrile-based carbon fibers having a fiber diameter DC _{A of 10} to 20 μm and 5-25 parts by mass of polyacrylonitrile-based carbon fibers having a fiber diameter DC _B. The carbon fiber has a diameter ratio DC _B / DC _A of 0.4 to 0.8, a thickness of 0.2 to 0.5 mm, and a bulk density of 0.15 to 0.35 g / cm ^3. A polyacrylonitrile-based carbon fiber spun yarn fabric.
[0009]
[2] The spun yarn constituting the polyacrylonitrile-based carbon fiber spun woven fabric is a spun yarn of a polyacrylonitrile-based carbon fiber having a fiber diameter DO _A and a polyacrylonitrile-based carbon fiber having a fiber diameter DO _B. Polyacrylonitrile carbon fiber spun yarn fabric.
[0010]
[3] The polyacrylonitrile-based carbon fiber spun yarn fabric according to [1], wherein an electrical resistance value in the thickness direction is 3.5 mΩ or less.
[0011]
[4] 100 parts by mass of a polyacrylonitrile-based oxidized fiber having a fiber diameter DO _A of 13 to 26 μm and a poly having a fiber diameter DO _B having a diameter ratio DO _B / DO _A to the oxidized fiber of 0.4 to 0.8 100 parts by mass of a polyacrylonitrile-based carbon fiber having a fiber diameter DC _{A of 10} to 20 μm, which is obtained by carbonizing a polyacrylonitrile-based oxidized fiber spun yarn fabric comprising 5 to 25 parts by mass of an acrylonitrile-based oxidized fiber; a polyacrylonitrile-based carbon fiber spun yarn fabric consisting of polyacrylonitrile-based carbon fiber 5 to 25 parts by weight of the diameter DC _B, diameter ratio DC _B / DC _a of the carbon fiber be 0.4 to 0.8 A method for producing a polyacrylonitrile-based carbon fiber spun yarn fabric having a thickness of 0.2 to 0.5 mm and a bulk density of 0.15 to 0.35 g / cm ³ .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0013]
The PAN-based carbon fiber spun yarn fabric of the present invention has 100 parts by mass of a PAN-based carbon fiber (carbon fiber A) having a fiber diameter DC _{A of 10} to 20 μm and a PAN-based carbon fiber (carbon fiber B) 5 having a fiber diameter DC _B. ~ 25 parts by mass are mixed with each other. The mixed form of carbon fiber A and carbon fiber B is a carbon fiber spun yarn made of carbon fiber A and a carbon fiber spun yarn made of carbon fiber B, even if both fibers are mixed in one carbon fiber spun yarn. May be used to form a woven fabric.
[0014]
When the mass ratio (WC _B / WC _A ) between the carbon fiber A and the carbon fiber B is less than 0.05, the bulk density of the carbon fiber spun yarn fabric is lower than 0.15 g / cm ³ and the conductivity is poor. This is not preferable because it causes problems such as. When WC _B / WC _A exceeds 0.25, the dispersibility of the carbon fiber A and the carbon fiber B in the carbon fiber spun yarn fabric is deteriorated, and the strength of the spun yarn fabric is reduced. Therefore, it is not preferable.
[0015]
The diameter ratio DC _B / DC _A of carbon fibers constituting the PAN-based carbon fiber spun yarn fabric is 0.4 to 0.8. When the carbon fiber diameter ratio DC _B / DC _A is less than 0.4, it is preferable because the dispersion of the fibers occurs in the mixed state of the carbon fibers A and B and the strength of the carbon fiber spun yarn fabric is reduced. Absent. A carbon fiber diameter ratio DC _B / DC _A exceeding 0.8 is also not preferable because the strength of the carbon fiber spun yarn fabric decreases.
[0016]
The fiber diameter DC _A of the carbon fibers constituting the PAN-based carbon fiber spun yarn fabric is 10 to 20 μm. When the fiber diameter DC _A is less than 10 μm, the strength of the carbon fiber spun yarn fabric is lowered, which is not preferable. When the fiber diameter DC _A exceeds 20 μm, the processability of the spun yarn fabric is poor, which is not preferable.
[0017]
The thickness of the PAN-based carbon fiber spun yarn fabric is 0.2 to 0.5 mm.
[0018]
When the thickness of the PAN-based carbon fiber spun yarn fabric is less than 0.2 mm, when the carbon fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell, the electrode material has high conductivity, but the carbonization This is not preferable because it causes problems such as low strength and easy generation of carbon fine powder.
[0019]
When the thickness of the PAN-based carbon fiber spun yarn fabric exceeds 0.5 mm, when this carbon fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell, the electrode material has low conductivity and the battery performance is low. Since it falls, it is not preferable.
[0020]
The bulk density of the PAN-based carbon fiber spun yarn fabric is 0.15 to 0.35 g / cm ³ .
[0021]
When the bulk density of the PAN-based carbon fiber spun yarn fabric is less than 0.15 g / cm ³ , when this carbon fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell, the conductivity of the electrode material is low, Since battery performance falls, it is not preferable.
[0022]
When the bulk density of the PAN-based carbon fiber spun yarn fabric exceeds 0.35 g / cm ³ , when the carbon fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell, the electrode material has high conductivity. When carbonized, problems such as reduced strength and easy generation of carbon fine powder are undesirable.
[0023]
The electrical resistance value in the thickness direction of the PAN-based carbon fiber spun yarn fabric of the present invention is preferably 3.5 mΩ or less, and usually 0.5 to 3.5 mΩ in terms of the electrical resistance value obtained by measurement by a measurement method described later. It is.
[0024]
The PAN-based carbon fiber spun yarn fabric of the present invention can be produced by various methods and is not particularly limited.
[0025]
An example of a preferable production method is shown below. That is, first, 100 parts by mass of a PAN-based oxidized fiber (oxidized fiber A) having a fiber diameter DO _A of 13 to 26 μm and a fiber having a diameter ratio DO _B / DO _A to the oxidized fiber A of 0.4 to 0.8. After mixing 5 to 25 parts by mass of PAN-based oxidized fiber (oxidized fiber B) having a diameter of DO _B , a spun yarn fabric is processed to obtain a PAN-based oxidized fiber spun fabric, and the PAN-based oxidized fiber spun fabric is made of carbon. Can be manufactured. A conventionally known method can be adopted as the carbonization method.
[0026]
When the mass ratio (WO _B / WO _A ) between the oxidized fiber A and the oxidized fiber B is less than 0.05, the bulk density of the oxidized fiber spun yarn fabric is lower than 0.18 g / cm ³ , and the oxidized fiber Since the carbon fiber spun yarn fabric obtained by carbonizing the spun yarn fabric has a bulk density lower than 0.15 g / cm ³ and causes problems such as poor electrical conductivity, it is not preferable. When WO _B / WO _A exceeds 0.25, the dispersibility of oxidized fiber A and oxidized fiber B is poor, and carding, spinning, weaving, that is, spun yarn fabric processing, and carbonization Is not preferable because it becomes difficult.
[0027]
In this manufacturing method, since the carbon fiber A is derived from the oxidized fiber A and the carbon fiber B is derived from the oxidized fiber B, the specific gravity of the oxidized fiber A and the specific gravity of the oxidized fiber B are substantially the same. The value of the mass ratio (WO _B / WO _A ) between the oxidized fiber A and the oxidized fiber B is almost the same value as the mass ratio (WC _B / WC _A ) between the carbon fiber A and the carbon fiber B.
[0028]
When the oxidized fiber diameter ratio DO _B / DO _A is less than 0.4, when the oxidized fiber A and the oxidized fiber B are mixed, fiber dispersion unevenness occurs, and the strength of the oxidized fiber spun woven fabric decreases. When carbonized, problems such as the spun yarn fabric being easily cut and the carbon fine powder being easily generated are not preferable. When the diameter ratio DO _B / DO _A of the oxidized fiber exceeds 0.8, the bulk density of the oxidized fiber spun yarn fabric is likely to cause sliver breakage during carding after mixing the oxidized fiber A and the oxidized fiber B. Problems such as lower than 0.18 g / cm ³ , and the bulk density of carbon fiber spun yarn fabric obtained by carbonizing oxidized fiber spun yarn fabric is lower than 0.15 g / cm ^3, resulting in poor electrical conductivity. This is not preferable.
[0029]
When the fiber diameter DO _A is less than 13 μm, the strength of the carbon fiber spun yarn fabric obtained by carbonizing the oxidized fiber spun yarn fabric is unfavorable. When the fiber diameter DO _A exceeds 26 μm, the oxidized fiber A and the oxidized fiber B are mixed and then carded to obtain a sliver, and the sliver is finely spun and weaved to obtain an intermediate oxidized fiber spun yarn. When obtaining a woven fabric, carding processability, spinning processability, and weaving processability are deteriorated, which is not preferable.
[0030]
The PAN-based oxidized fiber spun yarn fabric is obtained by dispersing oxidized fibers A and oxidized fibers B having a diameter ratio DO _B / DO _A of the oxidized fibers of 0.4 to 0.8 in the mass ratio, It can be produced by carding to obtain a sliver, spinning the sliver to obtain a spun yarn, and weaving the spun yarn into a sheet. A conventionally well-known method can be suitably employ | adopted for these spun yarn fabric processing methods.
[0031]
The bulk density of the PAN-based oxidized fiber spun yarn fabric is preferably 0.18 to 0.45 g / cm ³ .
[0032]
When the bulk density of the PAN-based oxidized fiber spun yarn fabric is less than 0.18 g / cm ^{3, the} carbon fiber spun yarn fabric obtained by carbonizing the oxidized fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell. When this is done, it is not preferable because the conductivity of the electrode material is low and the battery performance deteriorates.
[0033]
In order to obtain a PAN-based oxidized fiber spun yarn fabric having a bulk density exceeding 0.45 g / cm ³ , a compression treatment subject to excessive compression treatment conditions is required. Is unfavorable because it decreases. In addition, when carbonizing this PAN-based oxidized fiber spun yarn fabric subjected to excessive compression treatment to obtain a PAN-based oxidized fiber spun yarn fabric, when the obtained carbon fiber spun yarn fabric is used as an electrode material for a polymer electrolyte fuel cell Although the electrode material has high electrical conductivity, it is not preferable because it causes problems such as reduced strength and easy generation of fine carbon powder during carbonization.
[0034]
【Example】
The present invention will be specifically described with reference to the following examples and comparative examples.
[0035]
Oxidized fiber spun yarn fabric and carbon fiber spun yarn fabric were prepared under the conditions of the following Examples and Comparative Examples. Various physical properties of raw material oxidized fiber, oxidized fiber spun yarn fabric, and carbon fiber spun yarn fabric were measured by the following methods.
[0036]
Specific gravity: Measured by liquid replacement method (JIS R-7601, replacement liquid: ethyl alcohol).
[0037]
Thickness: The thickness at a load (2.8 kPa) of 200 g was measured with a circular pressure plate having a diameter of 30 mm.
[0038]
Mass per unit area: The mass per unit area was calculated from the size and mass of oxidized fiber spun yarn fabric or carbon fiber spun yarn fabric.
[0039]
Bulk density: Calculated from the thickness and basis weight measured under the above conditions.
[0040]
Diameter of fiber constituting the spun yarn fabric and its content: As shown in the schematic explanatory diagram of the fiber diameter measuring method in FIG. 1, the spun yarn fabric to be measured is cut into 5 cm square, and this 5 cm square cut spun yarn The fabric 2 was further cut into strips 4 at intervals of 3 mm. Next, after loosening the strip 4 with tweezers, it was put into a 200 ml beaker 6, 150 ml of 1% by volume ethanol aqueous solution was added thereto, and the fiber 8 was dispersed in the ethanol aqueous solution.
[0041]
The fiber dispersion 10 was collected with a dropper, placed on a preparation, and a photomicrograph was taken at a magnification of 200 times. From this micrograph, the fiber diameter was measured for n = 100 specimens. The measured value of the fiber diameter was obtained up to one decimal place in μm.
[0042]
When the measured value of the fiber diameter was summarized in a histogram with the horizontal axis representing the fiber diameter and the vertical axis representing the number of fibers, a thick fiber peak and a thin fiber peak appeared. The average value of each fiber diameter was calculated from the number of fibers at a fiber diameter of ± 10% of each peak. When the measurement object was a carbon fiber spun yarn fabric, DC _A μm and DC _B μm were used.
[0043]
The mass ratio (WC _B / WC _A ) of the content of fine fibers and thick fibers was calculated using the formula (number of fine fibers × DC _B ² ) / (number of thick fibers × DC _A ² ).
[0044]
Electrical resistance value: Carbon fiber spun yarn fabric was sandwiched between two 50 mm square gold plated electrodes at a pressure of 1 MPa, and the electrical resistance value (R (mΩ)) between the two electrodes was measured. The resistance value in thickness was displayed.
[0045]
Cell voltage: A carbon fiber spun yarn fabric was cut into a 50 mm square, and a catalyst (Pt-Ru) was supported at 0.3 mg / cm ² to obtain a polymer electrolyte fuel cell electrode material. A cell was constructed by joining the electrode material cut to 50 mm square on both sides of the polymer electrolyte membrane (Nafion 117), and the cell voltage was measured at a temperature of 80 ° C. and a current density of 1.60 A / cm ² .
[0046]
Example 1
As shown in Table 1, to 100 parts by mass of PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39, and a fiber diameter of 14.0 μm (DO _A ) (cut length 51 mm), a fineness of 0.90 dtex, After 23 parts by mass of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 10.0 μm (DO _B ) are uniformly mixed with a blended cotton machine, carding is performed to obtain a sliver It was. The fiber diameter ratio DO _B / DO _A is calculated to be 0.71 from the above DO _A and DO _B values. Further, the mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated as 0.23.
[0047]
The sliver was finely spun to produce 40-count double yarn (PAN-based oxidized fiber spun yarn (spun yarn count: 2/40)). Weaving this oxidized fiber spun yarn, weaving form: plain weave, number of spun yarns driven 40 / in (40 / (2.54 cm)), basis weight 160 g / m ² , thickness 0.45 mm, and bulk density 0. A PAN-based oxidized fiber spun yarn fabric of 36 g / cm ³ was obtained.
[0048]
This PAN-based oxidized fiber spun yarn fabric was carbonized at a treatment temperature of 1500 ° C. for 2 minutes in a nitrogen atmosphere to obtain a PAN-based carbon fiber spun yarn fabric.
[0049]
As shown in Table 1, the obtained PAN-based carbon fiber spun yarn fabric has a basis weight of 97 g / m ² , a thickness of 0.40 mm, a bulk density of 0.24 g / cm ³ , an electric resistance value of 2.1 mΩ, The cell voltage was 0.74 V, and the spun yarn fabric had good physical properties.
[0050]
In this PAN-based carbon fiber spun yarn fabric, the diameter of the thick carbon fiber A derived from the raw material oxidized fiber A is 11.1 μm (DC _A ), and the diameter of the thin carbon fiber B derived from the raw material oxidized fiber B is 8.1 μm ( DC _B ). The value of the fiber diameter ratio DC _B / DC _A is calculated as 0.73 from these values of DC _A and DC _B. The mass ratio WC _B / WC _A of the carbon fibers A and the carbon fiber B was 0.23.
[0051]
Example 2
As shown in Table 1, 100 mass parts of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39 and a fiber diameter of 14.0 μm (DO _A ), a fineness of 0.72 dtex, 10 parts by mass of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 8.0 μm (DO _B ) are uniformly mixed with a blended cotton machine, and then carded to obtain a sliver It was. The fiber diameter ratio DO _B / DO _A is calculated to be 0.57 from the above DO _A and DO _B values. Further, the mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated as 0.25.
[0052]
The sliver was finely spun to produce 40-count double yarn (PAN-based oxidized fiber spun yarn (spun yarn count: 2/40)). Weaving this oxidized fiber spun yarn, weaving form: plain weave, spun yarn number of 40 yarns / in (40 yarns / (2.54 cm)), basis weight 160 g / m ² , thickness 0.47 mm, bulk density 0. A PAN-based oxidized fiber spun yarn fabric of 34 g / cm ³ was obtained.
[0053]
This PAN-based oxidized fiber spun yarn fabric was carbonized at a treatment temperature of 1500 ° C. for 2 minutes in a nitrogen atmosphere to obtain a PAN-based carbon fiber spun yarn fabric.
[0054]
As shown in Table 1, the obtained PAN-based carbon fiber spun yarn fabric has a basis weight of 88 g / m ² , a thickness of 0.45 mm, a bulk density of 0.20 g / cm ³ , an electrical resistance value of 2.8 mΩ, The cell voltage was 0.70 V, and the spun yarn fabric had good physical properties.
[0055]
In this PAN-based carbon fiber spun yarn fabric, the diameter of the thick carbon fiber A derived from the raw material oxidized fiber A is 10.5 μm (DC _A ), and the diameter of the thin carbon fiber B derived from the raw material oxidized fiber B is 6.5 μm ( DC _B ). From these values of DC _A and DC _B, the value of the fiber diameter ratio DC _B / DC _A is calculated as 0.62. Further, the mass ratio WC _B / WC _A between the carbon fiber A and the carbon fiber B was 0.10.
[0056]
Example 3
As shown in Table 1, to 100 parts by mass of PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39, and a fiber diameter of 14.0 μm (DO _A ) (cut length 51 mm), a fineness of 0.90 dtex, 15 parts by mass of a cut fiber (cut length: 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 10.0 μm (DO _B ) are uniformly mixed with a blended cotton machine and then carded to obtain a sliver It was. The fiber diameter ratio DO _B / DO _A is calculated to be 0.71 from the above DO _A and DO _B values. The mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated to be 0.15.
[0057]
The sliver was finely spun to produce a 55th yarn (PAN-based oxidized fiber spun yarn (spun yarn count: 2/55)). Weaving this oxidized fiber spun yarn, weaving form: plain weave, spun yarn number of 53 / in (53 / (2.54 cm)), basis weight 145 g / m ² , thickness 0.39 mm, bulk density 0. A PAN-based oxidized fiber spun yarn fabric of 37 g / cm ³ was obtained.
[0058]
This PAN-based oxidized fiber spun yarn fabric was carbonized at a treatment temperature of 1500 ° C. for 2 minutes in a nitrogen atmosphere to obtain a PAN-based carbon fiber spun yarn fabric.
[0059]
As shown in Table 1, the obtained PAN-based carbon fiber spun yarn fabric has a basis weight of 87 g / m ² , a thickness of 0.35 mm, a bulk density of 0.25 g / cm ³ , an electric resistance value of 2.0 mΩ, The cell voltage was 0.75 V, and the spun yarn fabric had good physical properties.
[0060]
In this PAN-based carbon fiber spun yarn fabric, the diameter of the thick carbon fiber A derived from the raw material oxidized fiber A is 11.0 μm (DC _A ), and the diameter of the thin carbon fiber B derived from the raw material oxidized fiber B is 8.0 μm ( DC _B ). The value of the fiber diameter ratio DC _B / DC _A is calculated as 0.73 from these values of DC _A and DC _B. Moreover, mass ratio WC _B / WC _A of carbon fiber A and carbon fiber B was 0.15.
[0061]
[Table 1]

[0062]
Comparative Example 1
As shown in Table 2, to 100 parts by mass of a cut fiber (cut length 51 mm) of a PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39 and a fiber diameter of 14.0 μm (DO _A ), a fineness of 0.90 dtex, 4 parts by mass of a cut fiber (cut length: 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 10.0 μm (DO _B ) are uniformly mixed by a blended cotton machine, and then carded to obtain a sliver It was. The fiber diameter ratio DO _B / DO _A is calculated to be 0.71 from the above DO _A and DO _B values. The mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated as 0.05.
[0063]
The sliver was finely spun to produce 40-count double yarn (PAN-based oxidized fiber spun yarn (spun yarn count: 2/40)). Weaving this oxidized fiber spun yarn, weaving form: plain weave, number of spun yarns driven 40 / in (40 / (2.54 cm)), basis weight 160 g / m ² , thickness 0.60 mm, bulk density 0. A PAN-based oxidized fiber spun yarn fabric of 27 g / cm ³ was obtained.
[0064]
This PAN-based oxidized fiber spun yarn fabric was carbonized at a treatment temperature of 1500 ° C. for 2 minutes in a nitrogen atmosphere to obtain a PAN-based carbon fiber spun yarn fabric.
[0065]
The obtained PAN-based carbon fiber spun yarn fabric has a basis weight of 87 g / m ² , a thickness of 0.61 mm, a bulk density of 0.14 g / cm ³ , an electrical resistance value of 3.8 mΩ, as shown in Table 1. The cell voltage was 0.67 V, and it was not a spun yarn fabric with good physical properties.
[0066]
In this PAN-based carbon fiber spun yarn fabric, the diameter of the thick carbon fiber A derived from the raw material oxidized fiber A is 11.1 μm (DC _A ), and the diameter of the thin carbon fiber B derived from the raw material oxidized fiber B is 8.0 μm ( DC _B ). From these values of DC _A and DC _B, the value of the fiber diameter ratio DC _B / DC _A is calculated as 0.72. The mass ratio WC _B / WC _A between the carbon fiber A and the carbon fiber B was 0.04.
[0067]
Comparative Example 2
As shown in Table 2, 100 mass parts of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39, and a fiber diameter of 14.0 μm (DO _A ), a fineness of 0.72 dtex, After mixing 84 parts by mass of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 8.0 μm (DO _B ) with a blended cotton machine, carding is performed to obtain a sliver It was. The fiber diameter ratio DO _B / DO _A is calculated to be 0.57 from the above DO _A and DO _B values. Further, the mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated as 0.84.
[0068]
When the above sliver was spun and an attempt was made to produce a PAN-based oxidized fiber spun yarn, yarn breakage occurred frequently during this spinning, and a spun yarn could not be obtained.
[0069]
Comparative Example 3
As shown in Table 2, to 100 parts by mass of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber A having a fineness of 2.0 dtex, a specific gravity of 1.39, and a fiber diameter of 14.0 μm (DO _A ), a fineness of 0.45 dtex, After mixing 20 parts by mass of a cut fiber (cut length 51 mm) of PAN-based oxidized fiber B having a specific gravity of 1.40 and a fiber diameter of 4.5 μm (DO _B ) with a blended cotton machine, carding is performed to obtain a sliver It was. The value of the fiber diameter ratio DO _B / DO _A is calculated as 0.32 from the values of DO _A and DO _B. Further, the mass ratio WO _B / WO _A between the oxidized fiber A and the oxidized fiber B is calculated as 0.20.
[0070]
When the sliver was finely spun and an attempt was made to produce a PAN-based oxidized fiber spun yarn, yarn breakage occurred frequently during this spinning, and a spun yarn could not be obtained.
[0071]
[Table 2]

[0072]
【The invention's effect】
Since the PAN-based carbon fiber spun yarn fabric of the present invention has the above-described configuration, it is thin, has a low basis weight, has high strength, has a high bulk density, and has a low electrical resistance.
[0073]
The method for producing a PAN-based carbon fiber spun yarn fabric comprising thin carbon fibers and thick carbon fibers according to the present invention provides a PAN-based oxidized fiber spun yarn fabric as an intermediate raw material comprising thin oxidized fibers and thick oxidized fibers. Obtained by carbonization. By carbonizing this oxidized fiber spun yarn fabric, the thin oxidized fiber contracts greatly, and the thin fiber enters between the thick fibers to increase the density of the spun yarn fabric and increase the electrical conductivity. The fiber is carbonized to achieve high strength of the spun yarn fabric.
[0074]
The carbon fiber spun yarn fabric produced by the production method of the present invention has a low basis weight and a thin thickness, so it is light in weight and has high strength, and is useful as a carbon fiber material such as an electrode material for polymer fuel cells. Material.
[0075]
Furthermore, according to the method for producing a PAN-based carbon fiber spun yarn fabric of the present invention, a step such as a compression treatment is not required, and carbon fine powder is hardly generated.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a method for measuring the diameter and content of fibers constituting a spun yarn fabric.
[Explanation of symbols]
2 Spun yarn fabric cut to 5 cm square 4 Strips cut at intervals of 3 mm 6 200 ml beaker 8 Fiber 10 Fiber dispersion

Claims

_A polyacrylonitrile-based carbon fiber spun yarn fabric comprising 100 parts by mass of a polyacrylonitrile-based carbon fiber having a fiber diameter DC _A of 10-20 μm and 5-25 parts by mass of a polyacrylonitrile-based carbon fiber having a fiber diameter DC _B , A carbon fiber having a diameter ratio DC _B / DC _A of 0.4 to 0.8, a thickness of 0.2 to 0.5 mm, and a bulk density of 0.15 to 0.35 g / cm ³ Acrylonitrile carbon fiber spun yarn fabric.

Yarn constituting the polyacrylonitrile-based carbon fiber spun yarn fabric of claim 1 which is the spun yarn of the polyacrylonitrile-based polyacrylonitrile-based carbon fibers of the carbon fibers and the fiber diameter D C _B fiber diameter D C _A Polyacrylonitrile-based carbon fiber spun yarn fabric.

The polyacrylonitrile-based carbon fiber spun yarn fabric according to claim 1, wherein an electric resistance value in a thickness direction is 3.5 mΩ or less.

100 parts by mass of polyacrylonitrile-based oxidized fiber having a fiber diameter DO _A of 13 to 26 μm and a polyacrylonitrile-based oxide having a fiber diameter DO _B having a diameter ratio DO _B / DO _A to the oxidized fiber of 0.4 to 0.8 100 parts by mass of polyacrylonitrile-based carbon fiber having a fiber diameter DC _{A of 10} to 20 μm, and a fiber diameter DC _B , characterized by carbonizing a polyacrylonitrile-based oxidized fiber spun yarn fabric comprising 5 to 25 parts by mass of fibers A polyacrylonitrile-based carbon fiber spun yarn woven fabric composed of 5-25 parts by mass of a polyacrylonitrile-based carbon fiber, wherein the carbon fiber has a diameter ratio DC _B / DC _A of 0.4-0.8, and has a thickness of Is a method for producing a polyacrylonitrile-based carbon fiber spun yarn fabric having a bulk density of 0.15 to 0.35 g / cm ³ .