JP3834999B2

JP3834999B2 - Prepreg of reinforced fiber fabric and method for producing the same

Info

Publication number: JP3834999B2
Application number: JP14060698A
Authority: JP
Inventors: 明西村; 清本間; 郁夫堀部
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 1997-05-15
Filing date: 1998-05-07
Publication date: 2006-10-18
Anticipated expiration: 2018-05-07
Also published as: JPH11217450A

Description

【０００１】
【発明の属する技術分野】
本発明は、繊維強化プラスチック（以下ＦＲＰと呼称）を形成するに用いる強化繊維織物のプリプレグおよびプリプレグの製造方法に関する。
【０００２】
【従来の技術】
強化繊維を樹脂で補強してなるＦＲＰ、なかでも炭素繊維強化プラスチック（ＣＦＲＰ）は比強度および比弾性率に優れることから、軽量化によって燃費が大幅に向上する航空機の構造材や内装材として使われている。しかし、炭素繊維が高価なこともあって、軽量化効果が大きいとされる航空機であっても適用部位が制限されている。
【０００３】
とくに、航空機のフラップ、フェアリングやエルロンなどの２次構造材や、化粧室、天井パネル、ウンドウパネルや天井の荷物入れなどの内装材は、ハニカムを芯材とし、スキン材にＣＦＲＰを使用したハニカムサンドイッチ構造体が多用されている。
【０００４】
これらのハニカムサンドイッチ構造体の製造方法は、主として、ハニカムに炭素繊維織物からなるプリプレグを重ね合わせ加熱・加圧することによって、プリプレグの熱硬化性樹脂の硬化とハニカムとＣＦＲＰの接着を同時に行う、いわゆるハニカム・コキュアー法で成形される。ハニカム・コキュアー法による成形は、樹脂の硬化とＣＦＲＰの接着を同時に行うから、成形が大幅に簡素化される。しかし、成形の際、ハニカムのコアーに接する箇所のプリプレグは加圧されるが、コアに接しない部分は加圧されないこともあって、プリプレグの中に部分的に炭素繊維が存在しない大きな目明き部が存在すると、加圧されない部分のＣＦＲＰスキンに樹脂欠落による穴が開く。その対策として、たて糸とよこ糸によって形成される空隙の小さな織物によるプリプレグが用いられるが、このような織物はフイラメント数が３，０００フイラメントの細い炭素繊維糸条からなり、たて糸とよこ糸によって形成される空隙の小さな織物で、炭素繊維目付が小さな、薄い織物である。しかし、炭素繊維糸条が細いから、炭素繊維の生産効率が悪くまた織物の生産速度も遅く高価な材料となる。
【０００５】
これに対し、糸条が太いほど強化繊維糸条は安価であるが、太い糸条から強化繊維重量の小さな、薄い織物を製造すると、たて糸とよこ糸によって形成される空隙が大きな織物となってしまう。一方、太い強化繊維糸条を使用して薄くて、繊維分散が均一でカバーファクターの大きな扁平糸織物およびその製造方法を、たとえば特開平７−３００７３９号公報で提案した。この織物は、扁平なたて糸やよこ糸からなり、かつ薄い織物であるから織糸の屈曲（クリンプ）が小さく、そのＦＲＰの機械的性質は極めて優れている。しかしながら、この方法は糸の扁平性を保つための糸道、解舒撚りが入らないようにするためのよこ糸供給システムや扁平状の糸を把持するためなどの特別な装置が必要となり、厄介である。また、糸の扁平性を保ちながら製織するから不安定で、途中で扁平性が潰れ細くなり、たて糸とよこ糸によって形成される空隙が部分的に大きくなり欠点となることがある。
【０００６】
ＦＲＰの成形は種々の方法で行われているが、高性能のＦＲＰを得る方法として、成形用基材は、硬化剤を入れたＢステージ状態の樹脂を織物などのシート材にあらかじめ所定量含浸させたプリプレグの形で使われることが多い。このプリプレグの製造方法として、樹脂をフイルム状に加工し、これをシート材と合わせ、加熱・加圧してシート状に樹脂を含浸させるいわゆる乾式加工方法と、硬化剤を入れた固形樹脂やＢステージ状態の樹脂をメタノールやＭＥＫ（メチルエチルケトン）等の低温の沸点を有する溶剤で希釈し、シート材に樹脂含浸させたのち、溶剤を乾燥させる湿式加工方法がある。乾式加工方法は湿式加工方法に比べ溶剤の回収の必要が無いし、残存溶媒の管理が不要であるなどの利点はあるが、樹脂の種類によってはフイルム化が出来ない。また硬化剤の種類によっては樹脂中に細かく均一に分散することが出来ないケースもあるので、湿式加工方法も用いられている。
【０００７】
前述の如く、通常、糸条が太いほど強化繊維は安価であることから、その様な強化繊維で薄くて、繊維分散が均一でカバーファクターの大きな扁平糸織物およびその製造方法を、たとえば特開平７−３００７３９号公報で提案した。この織物は、前述したように、扁平なたて糸やよこ糸からなり、かつ薄い織物であるから織糸の屈曲（クリンプ）が小さく、ＦＲＰにした際の機械的性質は極めて優れている。しかし、太い糸で織物目付が小さな織物であるから、たて糸とよこ糸の交錯点数が少ない織物となる。
【０００８】
そこで、先に、プリプレグ加工で形態の安定性対策として低融点ポリマーで目どめ加工した織物を提案した。実際にこの織物でプリプレグ加工すると、織物の良好な繊維分散状態が確保された、すなわちカバーファクターの大きなプリプレグが得られることが分かった。しかしながら、とくには、織物の状態でたて糸およびよこ糸が充分に拡がった扁平状態のものが、プリプレグ加工の工程でその織糸の扁平状態が潰れ、織糸が細くなりメッシュ状になってしまう事態も発生した。プリプレグ加工の工程中の状態を観察すると、織糸の扁平状態の潰れが発生するケースでは、樹脂を溶剤で希釈した樹脂バスを織物が通過した直後には織糸の扁平状態が保たれているが、乾燥ゾーンに入って暫くすると、徐々に扁平状態が潰れ始めた。一方、織物プリプレグで織糸の扁平状態が保たれているケースでは乾燥ゾーンに入っても扁平状態が潰れることはなかった。つまり、目どめ剤は単に工程での織物の取扱い性の改善のみならず、湿式プリプレグ加工時における扁平糸織物の織糸の扁平状態を保つ役割を果たしていることがわかった。
【０００９】
【発明が解決しようとする課題】
本発明の目的は、従来の技術における上述した問題点を解決するとともに上記のような知見に基づき、繊維分散が均一であり、織糸が扁平状態でカバーファクターの大きなプリプレグを製造できる、湿式プリプレグの製造方法、およびその方法により製造された、繊維分散が均一であり、織糸が扁平状態でカバーファクターの大きなプリプレグを提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を達成するために、本発明の強化繊維織物の湿式プリプレグの製造方法は、糸幅が３〜２０ｍｍの範囲にあり、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり、２，５００〜２５，０００個でカバーファクターが９０％以上の強化繊維織物を用い、
（１）強化繊維織物にポリマーからなる目どめ剤を被覆した低熱収縮性の補助糸を線状に配置して、よこ糸および／またはたて糸の糸幅全体にわたって接着し、
（２）該強化繊維織物を、熱硬化性樹脂を、少なくとも８０％以上が前記ポリマーに対し不溶性である溶剤Ａで希釈した溶液に浸漬し、
（３）その後、熱風で溶剤を乾燥させ、
（４）カレンダーロールかけする、
ことを特徴とする方法からなる。
【００１２】
また、本発明の強化繊維織物の湿式プリプレグの製造方法は、糸幅が３〜２０ｍｍの範囲にあり、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり、２，５００〜２５，０００個でカバーファクターが９０％以上の強化繊維織物を用い、
（１）ポリマーの目どめ剤からなる不織布を強化繊維織物の少なくとも片面に配置し、強化繊維織物のたて糸およびよこ糸を糸幅全体にわたって接着し、
（２）該強化繊維織物を、熱硬化性樹脂を、少なくとも８０％以上が前記熱融着性繊維に対し不溶性である溶剤Ａで希釈した溶液に浸漬し、
（３）その後、熱風で溶剤を乾燥させ、
（４）カレンダーロールかけする、
ことを特徴とする方法からなる。
【００１３】
また、本発明に係る強化繊維織物の湿式プリプレグの製造方法は、糸幅が３〜２０ｍｍの範囲にあり、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり、２，５００〜２５，０００個でカバーファクターが９０％以上の強化繊維織物を用い、
（１）ポリマーの目どめ剤からなるフィルムを強化繊維織物の少なくとも片面に配置し、強化繊維織物のたて糸およびよこ糸を糸幅全体にわたって接着し、
（２）該強化繊維織物を、熱硬化性樹脂を、少なくとも８０％以上が前記熱融着性フィルムに対し不溶性である溶剤Ａで希釈した溶液に浸漬し、
（３）その後、熱風で溶剤を乾燥させ、
（４）カレンダーロールかけする、
ことを特徴とする方法からなる。
【００１４】
さらに、本発明に係る強化繊維織物のプリプレグは、このような方法によって得られる、糸幅が３〜２０ｍｍの範囲にあり、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり２，５００〜２５，０００個でカバーファクターが９０％以上であることを特徴とするものからなる。
【００１６】
本発明のプリプレグの製造に用いる強化繊維織物はたて糸とよこ糸の交錯点数が、織物の強化繊維糸条の糸拡げに影響するので重要であり、１平方メートル当たり２，０００〜７０，０００個の範囲にあることが好ましい。これは、通常の強化繊維織物、たとえば炭素繊維糸条が３，０００フイラメントの炭素繊維目付が２００ｇ／ｍ²の平織物の交錯点数が２５０，０００個であるのに比べて極めて少ない。たて糸とよこ糸の交錯点数が少ないと、たて糸とよこ糸の拘束状態が緩やかになるので、たとえ、カバーファクターが７０％程度のたて糸とよこ糸によって形成される空隙が大きなメッシュ状の織物でも、織物に樹脂含浸していると、すなわち樹脂中に強化繊維が存在する状態であると、カレンダーロールによって樹脂中に強化繊維が移動し、糸の幅を拡げることが出来るのである。なお、交錯点数が１平方メートル当たり２，０００個未満であると、たて糸とよこ糸の交錯による拘束が甘くなるので、プリプレグ工程のロールに織物が通過する際、ガイドロールとの接触によっても簡単に織物の糸がずれ、目ずれしたりするので好ましくない。また、７０，０００個を越えると、たて糸とよこ糸の交錯による拘束が強くなるので糸拡げが完全に行なえなくなり、プリプレグに樹脂のみが充填されて強化繊維が存在しない目明き部が残るので好ましくない。また、カバーファクターが７０％以下の織物となると、カレンダーロールで糸拡げ操作を行っても、たて糸とよこ糸によって形成される空隙が大きすぎて、隣接する糸条間を埋めるまで糸拡げが行えない、つまりカバーファクターの大きなプリプレグを得ることが困難となるのである。
【００１７】
なお、本発明でいう１平方メートル当たりのたて糸とよこ糸の交錯点数とは、たて糸とよこ糸が交錯している点数をいう。たとえば、たて糸とよこ糸が１本交互に交錯する平組織の場合は［１平方メートル当たりのたて糸本数×１平方メートル当たりのよこ糸本数］個となり、たて糸とよこ糸が２本交互に交錯する２／２の平組織の場合は［１平方メートル当たりのたて糸本数／２×１平方メートル当たりのよこ糸本数／２］個となる。
【００１８】
ここで、カバーファクターＣｆとは、織物の織糸間に形成される空隙部または空隙部に樹脂のみが充填され強化繊維が存在しない目明き部分に関係する要素で、織物または織物プリプレグ上に面積Ｓ₁の領域を設定したとき、面積Ｓ₁の内において織糸によって形成される空隙部の面積、または樹脂のみが充填され強化繊維が存在しない目明き部分の面積をＳ₂とすると、次の式で定義される値をいう。なお、プリプレグで目明き部の面積を測定しにくい場合は、プリプレグの下方から光を当てると、強化繊維の部分と強化繊維が存在せず樹脂のみが充填された部分を明確に区分することができる。
カバーファクターＣｆ＝［（Ｓ₁−Ｓ₂）／Ｓ₁］×１００
【００１９】
また、本発明に係る強化繊維織物の湿式プリプレグの製造においては、まず、本発明を完成するに際し、扁平状態が潰れる現象を考察した。すなわち、扁平状態が潰れる現象を考察するに、糸幅が３〜２０ｍｍ、糸幅／糸厚み比が２０以上の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が平方メートル当たり２，５００〜２５，０００個の織物は、通常の織物に比べ交錯点数が１／１０〜１／２０と極めて少なくなっているので、たて糸とよこ糸の織糸の交錯による織糸の拘束が緩やかであり、また糸束は無撚糸束内で繊維同士による交絡もないから、
１）湿式プリプレグ加工の際、このような織物を、樹脂を溶剤で希釈した溶液に浸し、溶剤を乾燥させると、織物に付着した溶液の樹脂粘度が徐々に大きくなり、溶液の表面張力が扁平状の織糸の幅の内側に働き、すなわち、たて糸およびよこ糸の幅を狭める方向に働き、織糸の扁平状態が潰れてしまう。
【００２０】
２）また、湿式プリプレグ加工における溶剤の乾燥は、乾燥効率を向上させるため熱風で行うが、熱風が僅かながら存在する織物の目明き部を通過し、目明き部を通過する空気によってたて糸およびよこ糸の糸幅を狭める方向に力が働き、織糸の扁平状態が潰れてしまう。
【００２１】
３）さらに、たて型乾燥炉では、上部の樹脂含浸させた織物には、織物の供給張力以外に織物の自重と溶液の重量が加わり、織物のたて糸方向に張力が働いている。この張力によって、クリンプしていたたて糸が真っ直ぐになり、よこ糸のクリンプが大きくなる。この織物構造の変化、すなわちクリンプ・インタージェンジの際、よこ糸がたて糸の幅を狭める方向に作用する。
【００２２】
また、目どめ剤を強化繊維織物に線状に配置して、よこ糸および／またはたて糸が糸幅全体にわたって接着していると、扁平な織糸の幅全体にわたって繊維の位置を固定していることになる。湿式プリプレグ加工工程において、ある程度溶剤が乾燥すると、樹脂の粘度も大きくなるので、高粘度樹脂によって繊維同士を接着する力も大きくなり、たとえ上述したような糸幅を狭める力が働いても、織糸の扁平状態が潰れてしまうようなことはないが、少なくとも、溶剤の量が多くて樹脂粘度が小さい間は繊維同士の接着力が弱く、目どめ剤による織糸の幅方向の拘束が必要であることがわかった。
【００２３】
このような条件を満たすには、目どめ剤としてポリマーの使用量にもよるが、熱硬化性樹脂を少なくとも８０％以上がポリマーに不溶性の溶剤Ａで希釈するとよく、好ましくは溶剤Ａの全てを目どめ剤のポリマーに不溶性のものにするとよいことがわかった。８０％以上の溶剤がポリマーに不溶性であると、つまり２０％未満がポリマーに可溶性の溶剤Ｂであっても、ポリマーの溶解速度が遅くなり、織物が樹脂バスを通過し、乾燥ゾーンに入って少なくとも３〜５分間程度、つまり、ある程度溶剤が乾燥し、樹脂の粘度も大きくなるまでは、目どめ剤による織糸の幅方向の拘束が残っていて、織糸の扁平状態が潰れるようなことはなかった。溶剤のうち、ポリマーに不溶性の溶剤が８０％未満になるに従い、徐々に織糸の扁平状態が潰れ始め、プリプレグで目明きの箇所が増え始め、繊維分散が不均一となり、カバーファクターが徐々に小さなプリプレグとなった。
【００２４】
また、樹脂に対する希釈剤としての溶剤の量は、織物への付着樹脂量の設定によって決められ、プリプレグの樹脂量が３０〜６０重量％になるように溶液粘度を設定すればよい。
【００２５】
なお、本発明においては溶剤の１００％を目どめ剤のポリマーに不溶性の溶剤Ａとする必要は必ずしもなく、樹脂、硬化剤、難燃剤やその他の第３成分の混合にあたっては、目どめ剤のポリマーに可溶性の溶剤Ｂを若干量使用することができる。
【００２６】
本発明において、目どめ剤が、融点が１００〜１４０℃程度の共重合ナイロンであることが望ましく、とくにＦＲＰにしたとき共重合ナイロン、ナイロン６と１２の共重合ナイロン、ナイロン６、ナイロン６６および６１０の共重合ナイロン、ナイロン６、ナイロン１２、６６および６１０の共重合ナイロンは、樹脂の接着性がよいので好ましく、また融点が低いので目どめした織物の製造も容易である。なお、共重合ナイロンの融点および溶剤による溶解性は前記各種ナイロンポリマーの組み合わせや混合割合により、共重合の際のナイロンポリマーの結晶性の乱れの程度によって決まり、共重合ナイロンの種類によってはメタノールなどのアルコールに可溶なもの、あるいは不溶なものとなる。したがって、アルコールに可溶性の共重合ナイロンの溶剤Ａとしては、ＭＥＫ、アセトンやトルエンなどの非アルコール系のものとなる。
【００２７】
ここで、本発明における可溶性とは、２０℃の溶剤を入れたビーカに目どめ剤となるポリマー糸を入れ、１０分放置後に糸の形態が消滅し塊状となったり、または溶解して糸の痕跡が無くなってしまう状態を可溶性とし、糸の形態を保っている状態を不溶性とする。
【００２８】
また、本発明では、樹脂の希釈剤としてのメタノールは、価格が安い、沸点が低くプリプレグ加工の際の乾燥が容易であることから、希釈剤としてメタノールなどのアルコール系の溶剤を使用し、目どめ剤として共重合ポリエステルからなる低融点ポリエステルまたは不溶性の共重合ナイロンを使用することが出来る。なお、共重合ポリエステルは、アジピン酸、セバチン酸などの脂肪族ジカルボン酸類、フタル酸、イソフタル酸、ナフタリンジカルボン酸などの芳香族ジカルボン酸類および／またはヘキサヒドロテレフタル酸、ヘキサヒドロイソフタル酸などの脂環族ジカルボン酸類と、ジエチレングリコール、プロピレングリコール、パラキシレングリコールなどの脂肪族や脂環族ジオール類とを所定量含有し、所望に応じてパラヒドロキシ安息香酸などのオキシ酸類を添加した共重合エステルであり、たとえばテレフタル酸とエチレングリコールに、イソフタル酸および１，６−ヘキサンジオールなどを添加共重合させたポリエステルなどがある。
【００２９】
本発明における目どめ剤は上記の共重合ナイロンや低融点ポリエステルが好ましいが、上記以外にもポリエチレンやポリプロピレンなどの低融点ポリマーを使用することができる。
【００３０】
目どめ剤は、本質的にはＦＲＰのマトリックス樹脂を形成するものではなく、使用する樹脂の種類によっては、全く異質なものとなってしまうので、使用量は極力少ない方がよく、０．５〜１５ｇ／ｍ²の範囲が好ましい。０．５ｇ／ｍ²未満であると扁平な織糸の幅方向の拘束が弱くなり、湿式プリプレグ加工の際、織糸の細幅化を防ぐことが出来ない。また、１５ｇ／ｍ²を超えるとＦＲＰの機械的特性を低下させることがある。０．５〜１５ｇ／ｍ²の範囲であれば、織糸の細幅化を防ぐことが出来るし、ＦＲＰの機械的特性もさほど低下させることはない。
【００３１】
また、本発明においては目どめ剤が織糸の細幅化を防ぐことから、線状に配置する１本あたりのポリマーの量が重要となる。目どめ剤としてのポリマー量は、強化繊維糸条に対して０．２重量％〜２重量％の範囲程度が好ましい。
【００３２】
なお、本発明に使用する目どめ剤の線状の配置は、上述したように目どめ剤が糸形態をなしていると、わずかな目どめ剤の使用で効果的に目どめできるが、繊維が面方向にランダムに配列した不織布のような形態であってもよい。
【００３３】
【発明の実施の形態】
以下に、本発明の望ましい実施の形態を、図面を参照しながら説明する。
本発明の一実施態様に係るプリプレグの製造方法を図１に示す。図１において、下部に設置した樹脂バス２に、溶剤で希釈した溶液３を入れ、この樹脂バス２にロール状に巻かれた織物１を１．５ｍ／分〜５ｍ／分程度の速度で引き出しながら浸漬し、織物の繊維間に樹脂を含浸させ、これを、十分な長さの乾燥ゾーンを有し、頂部に回転ロール４を付けた縦型乾燥炉５に通す。
【００３４】
次に、樹脂バス通過後回転ロールまで直線的に溶液の付着した織物を立ち上がらせ、織物の上り側の壁面６の吹出し口７、８から熱風を織物面に直角方向に吹き付けて、ある程度溶剤を乾燥させた後、次に回転ロール４に通して織物の進行方向を反転させ、下り側の壁面９の吹出し口１０、１１からも熱風を織物面に直角方向に吹き付けて残りの溶剤を乾燥させる。なお、壁面における熱風吹出し口が上り側の壁面６および下り側の壁面９で各々２〜４分割し、各々の吹出し口からの熱風温度が異なるようにして、溶媒の乾燥状態を制御出来るようにしておくとが好ましい。また、織物の上昇部と下降部の乾燥温度が変更できるように縦型乾燥炉５の中央部に、織物面と並行するようにセパレータ１２を取り付けておくと、各乾燥ゾーンの温度を正確に設定することが出来る。
【００３５】
上記は通常、湿式法と呼ばれるプリプレグの製造方式であり、通常の方法となんら変わることはない。本発明においては、乾燥ゾーンを出た後の、樹脂が含浸し、まだ冷えないプリプレグを加圧し織糸を拡げるために一対のローラからなるカレンダーローラ１３を設置すると好ましい。プリプレグが温かいと、樹脂が柔らかいので糸拡げが容易となるのである。糸拡げ時のプリプレグの温度は、５０〜１５０℃が好ましく、５０℃未満であると樹脂が固くなり糸拡げが困難となる。また、１５０℃を越えると樹脂の硬化が促進されるので、室温まで温度が下がった時のプリプレグのタック（粘着性）の管理が困難となる。なお、プリプレグの温度が高くて樹脂粘度が高いと、カレンダーローラに樹脂が付着することがある。このような場合はローラにシリコーン樹脂やフッ素樹脂をコーテングして樹脂の付着を防ぐことが出来、また、カレンダーローラにプリプレグが入る前にプリプレグの上面と下面から、たとえばシリコーン樹脂を含浸した離形紙１４を供給し、プリプレグが直接ローラに接触しないようにして、ローラへの樹脂の付着を防ぐことが出来る。また、プリプレグの温度が低くて糸拡げが困難な場合は５０〜１５０℃に加熱したカレンダーローラで糸拡げすることもできる。また、樹脂含浸したプリプレグを一旦巻き取り、室温まで冷えたプリプレグを、５０〜１５０℃に予熱して温めながらカレンダーローラで糸拡げすることもできる。
【００３６】
カレンダーロールによる繊維の損傷を防ぐ意味合いから、乾燥後のプリプレグの樹脂に１〜６％程度の溶媒が残存するようにし、プリプレグに付着した樹脂を柔らかくしておくとよい。カレンダーローラによるプリプレグの加圧は、樹脂が柔らかいので線圧が１ｋｇ／ｃｍ〜５０ｋｇ／ｃｍ程度が好ましい。線圧が１ｋｇ／ｃｍ未満であると、溶媒が残り樹脂が柔らかく糸幅を拡げ易いとはいえ、糸拡げが不完全となり、たて糸とよこ糸の交錯によって形成される空隙を強化繊維で埋めることが出来ず、この部分が目明き状態となりカバーファクターが大きくならないし、カバーファクターが大きくなっても、部分的に目明き部が残り、均一なプリプレグとはならない。また、線圧が５０ｋｇ／ｃｍを越えると織物のたて糸とよこ糸の交錯点数が少ないため織物プリプレグのよこ糸が蛇行することがある。
【００３７】
ここで言う線圧とは、ローラに作用する総荷重（ｋｇ）をカレンダーロールを通過する織物の幅（ｃｍ）で割った値で示したものである。
【００３８】
なお、カレンダーローラによる加圧は、１本のローラと平板の間に樹脂含浸した織物プリプレグや織物と樹脂フイルムを挟んでもよいし、２本のローラの間に挟んでもよい。ローラまたは平板の材質は金属同士または金属とゴムとの組み合わせであってもよい。ローラの直径は通常２０〜３００ｍｍ程度である。
【００３９】
本発明に使用する強化繊維織物のカバーファクターが７０％以上であれば、本発明のプリプレグの製造法によって糸拡げを行いカバーファクターの高いプリプレグに加工することができるが、カバーファクターが必ずしも９０〜１００％の高い織物である必要はなく、カバーファクターが７０以上９０％未満であってもよい。たて糸とよこ糸の交錯点数が小さくて、かつカバーファクターが９０％以上の薄い織物を製造するにはたて糸およびよこ糸の扁平度を保つための特別な装置が必要となるが、カバーファクターが７０以上９０％未満の織物であれば通常の製織操作で織物を製造することができるから安価に織物を製造することができる。
【００４０】
なお、本発明の織物を構成するたて糸およびよこ糸の強化繊維糸条は実質的に撚りがない状態、つまり、糸をたて取り解舒する際の４回／ｍ程度の解舒撚りが入っていてもよい。本発明のプリプレグの製造方法によればカレンダーローラで糸拡げを行うから十分にカバーファクターの大きなプリプレグとすることができる。なお、好ましくは本発明の織物を構成するたて糸およびよこ糸の強化繊維糸条の撚り数が零で、マルチフイラメントが実質的に並行配列していた方が、糸拡げを均一に行うことができるので好ましい。強化繊維糸条に撚りがあると、撚りにより糸条がくびれて糸が細くなっている箇所を拡げることが必要となり、カレンダーローラの圧力を大きくするなどの、プリプレグの品質上からより厳しい条件が必要となるが、糸条の撚りが零であることにより緩やかな条件で糸拡げを行うことができるので好ましい。
【００４１】
また、本発明に用いる強化繊維としては、ガラス繊維、ポリアラミド繊維、炭素繊維などの高強度・高弾性率の強化繊維であり、なかでも、ＪＩＳＲ７６０１法による引張弾性率が２００ＧＰａ以上、引張強度が４，５００ＭＰａ以上の炭素繊維は高強度・高弾性率であるのみならず、耐衝撃性にも優れ、また、樹脂がフェノール樹脂であると、炭素繊維は燃焼しないので不燃性にも優れる。
【００４２】
なお、強化繊維が炭素繊維である場合、織物のたて糸とよこ糸の交錯点数を少なくして、カレンダーローラによって糸を拡げを容易にし、薄い織物のプリプレグを製造するという観点からは、炭素繊維糸条のフイラメント数が６，０００〜２４，０００本である。従来、航空機用途に使われている３，０００フイラメントの炭素繊維糸条に比べ、糸条の太さが２〜８倍となるから炭素繊維の製造にあたっての生産性が向上し、安価となる。なお、炭素繊維糸条のフイラメント数が２４，０００本を越えると、薄い織物ではたて糸とよこ糸の交錯点数が少なくなるので、プリプレグ工程で織物が目ずれし、プリプレグの品位が低下するので好ましくない。
【００４３】
また、本発明ではプリプレグ工程で織物が目ずれするような場合には、たて糸とよこ糸の交点を目どめ剤で接着することができる。低コストで、かつ少量の目どめ剤で目どめを行うという観点で、共重合ナイロン、共重合ポリエステル、ポリエチレン、ポリプロピレンなどの低融点のポリマーであることが好ましい。なかでも共重合ナイロンは炭素繊維との接着性がよいので、わずかな量で目どめすることができ、またＦＲＰを構成するマトリックス樹脂との接着性もよいので好ましく用いられる。これらの低融点ポリマー糸をたて糸または／およびよこ糸の強化繊維糸条と同時に織物に挿入し、織機上でポリマーの融点以上に加熱し、ポリマーを溶融することによって目どめした強化繊維織物を得られ、強化繊維織物の目どめ処理を安価に行うことができる。
【００４４】
また、プリプレグ工程で織物が目ずれするような場合の他の目どめ方法として、低融点ポリマーの目どめ剤からなる不織布、またはフイルムを強化繊維織物の少なくとも片面に配置し、目どめ剤の融点以上に加熱してポリマー溶融し、加圧することによって強化繊維織物のたて糸およびよこ糸を糸幅全体にわたって接着していることで、扁平な織糸の幅全体にわたって繊維の位置を固定することもできる。
【００４５】
この場合も低コストで、かつ少量の繊維目付、またはフイルム目付で目どめを行うという観点で、ポリ塩化ビニリデン、共重合ナイロン、共重合ポリエステル、ポリエチレン、ポリプロピレンなどの低融点熱融着性繊維であることが好ましい。なかでも共重合ナイロンは炭素繊維との接着性がよいので、わずかな繊維目付で目どめすることができ、またＦＲＰを構成するマトリックス樹脂との接着性もよいので好ましく用いられる。
【００４６】
目どめ剤は、前述の如く、本質的にはＦＲＰのマトリックス樹脂を形成するものではなく、使用する樹脂の種類によっては、全く異質なものとなってしまうので、使用量は極力少ない方がよく、０．５〜１５g/ｍ²の範囲が好ましい。この範囲であれば、十分な目どめが可能でありまたＦＲＰの機械的特性もさほど低下させることはない。
【００４７】
本発明に用いる樹脂は、エポキシ樹脂、不飽和ポリエステル樹脂、ビニルエステル樹脂やフェノール樹脂などの熱硬化性樹脂が用いられる。
【００４８】
また、本発明では、本発明の製造法から得られる、たて糸とよこ糸の交錯点数が１平方メートル当たり２，０００〜７０，０００個で、カバーファクターが９７％以上である強化繊維織物のプリプレグを特徴とする。従来の強化繊維織物に比べて交錯点数が少ないから深絞り成形性に優れる。また、交錯点数が少ないからカレンダーロールで糸が拡がるから、カバーファクターの大きなプリプレグとなり、このようなプリプレグはハニカムに数枚積層してハニカムコキュアー法で成形しても、加圧されない箇所のＣＦＲＰスキンに樹脂欠落による穴が開き難くなる。また、カバーファクターが９７％以上であるから、強化繊維織物の目明き面積も小さくなり、強化繊維が炭素繊維であるから耐火性に優れる。このようなプリプレグは、とくに火災の際の炎が遮断される。
【００４９】
たて糸とよこ糸が６，０００フィラメント以上の炭素繊維糸からなり、たて糸およびよこ糸の織り密度がほぼ同じで、織物の炭素繊維重量が１４０〜２４０ｇ／ｍ²の織物のプリプレグであると、機械的特性が長さ方向と幅方向が同じであり、また炭素繊維が（０゜／９０゜）の方向と、プリプレグをバイアス方向に裁断し、炭素繊維が（＋４５゜／−４５゜）の方向に配列するように交差積層することによって、機械的特性を簡単に疑似等方性とすることが可能である。なお、たて糸およびよこ糸の織り密度の比が２０％以内であれば、たて糸およびよこ糸の織り密度がほぼ同じであるとおおよそ見なしてよい。また、炭素繊維織物は３０〜６０重量％の通常の樹脂付着量で薄くて軽いプリプレグとなり、軽いサンドイッチ構造体が得られるから、とくに航空機に内装材として好ましく用いられる。また、従来の、炭素繊維糸条が３，０００フィラメント程度の同じ平組織で炭素繊維重量が同じ織物に比べてたて糸とよこ糸の交錯点数が１／４以下と少くなるので深絞り成形性に優れ、また炭素繊維糸条が太くなり安価となる。
【００５０】
たて糸とよこ糸が１２，０００フィラメント以上の炭素繊維糸からなり、たて糸およびよこ糸の織り密度が同じで、織物の炭素繊維重量が１４０〜２４０ｇ／ｍ²であると、交錯点数が従来の炭素繊維織物に比べて１／１６以下となり、６，０００フィラメントの糸条よりもより炭素繊維糸条が太くなるので、さらに安価で、通常の樹脂付着量で薄くて軽いプリプレグが得られるので好ましい。
なお、ここにおいてもたて糸およびよこ糸の織り密度の比が２０％以内であれば、たて糸およびよこ糸の織り密度が同じであると見なしてよい。
【００５１】
また、たて糸とよこ糸によって形成される織物プリプレグの目明き部の平均面積が１個当り１．５ｍｍ²以下であるとプリプレグの中に部分的に炭素繊維が存在しない目明き部が存在しても小さいので、ハニカム・コキュアー成形しても、加圧されない部分のＣＦＲＰスキンに樹脂欠落による穴が開くようなことはなく、表面が平滑なＣＦＲＰを表皮材とするハニカムサンドイッチパネルが得られる。
【００５２】
なお、本発明における目明き部の平均面積とは、たて糸とよこ糸の交錯によって形成される織物の空隙部の該当部にプリプレグにしても樹脂は充填されているが炭素繊維が存在しない目明き部１００個の平均値をいう。
【００５３】
また、本発明のプリプレグの製造法によって、たとえば、強化繊維糸条の太さ、織物のたて糸およびよこ糸密度、織物の繊維重量、湿式プリプレグのカレンダーローラ前の溶媒量、ローラの線圧やローラ掛けの際のプリプレグの温度を最適化することによって、強化繊維が開繊・拡幅し、たて糸とよこ糸によって形成される目明き部がなく、閉塞されているプリプレグが得られる。このようなプリプレグは火災の際の炎を完全に遮断することができ、また、ハニカムコキュアー法で成形したサンドイッチ構造体で、ＦＲＰスキンに樹脂欠落による穴を完全に防ぐことができるので、品質の均一なサンドイッチ構造体となり、品質管理が厳しい航空機部品などに好適である。
【００５４】
なお、本発明の閉塞状態とは、プリプレグに加工する前の織物のたて糸とよこ糸によって形成される空隙数が、２／３以上完全に塞がった状態をいい、条件のバラツキによって、完全に塞がらない箇所はあっても、空隙面積が小さいので、実質的には閉塞状態と同じ効果が得られる。
【００５５】
本発明に用いる織物の組織はとくに限定するものではないが、平組織であると形態が安定し、プリプレグ加工工程での目ずれを防ぐことができるので好ましい。
【００５６】
図２は、本発明に係る強化繊維織物の湿式プリプレグの製造方法で使用する目どめ扁平糸織物２１の一実施態様を示しており、たて糸２２およびよこ糸２３の織糸は、糸幅が３〜２０ｍｍ、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸２２とよこ糸２３の交錯点の数が１平方メートル当たり２，５００〜２５，０００個で、カバーファクターが９０％以上となっている。
【００５７】
ここで、糸の厚みはＪＩＳ−Ｒ３４１４，第５．４項に準じ、マイクロメータを用いて、そのスピンドルを静かに回転させて、測定面が試料面に平行に軽く接触し、ラチェットが３回音をたてたときに目盛りを読み、Ｎ＝１０の平均値の糸を厚みとする。
【００５８】
図２において、扁平なたて糸２２およびよこ糸２３の２方向に、糸幅のほぼ中央部に目どめ剤２４および目どめ剤２５が線状に接着し、たて糸とよこ糸をその交錯部で接着し、扁平なたて糸およびよこ糸の幅全体を目どめ剤で接着し、拘束している。
【００５９】
ここで、目どめの方向は必ずしもたて糸とよこ糸の２方向である必要はない。織糸の太さ、織密度や織物組織による織糸の拘束度合いにもよるが、少なくともよこ糸に目どめ剤が付着していると、たて糸幅全体が目どめ剤で拘束されていることになるから、織物のたて糸方向に張力が働くことによる織物構造の変化、すなわちクリンプ・インタージェンジによるたて糸幅の細幅化を防ぐことが出来る。
【００６０】
また、目どめ剤は糸幅の中央部に位置することは必ずしも必要ではない。よこ糸糸幅の中心に対して左右にずれ、たとえば強化織糸のたて糸とたて糸との間やよこ糸とよこ糸の間に位置していてもよい。また、たて糸とよこ糸をその交錯部で接着していると、交錯点が接着し織物の形態は安定するが、その必要は必ずしもなく、たて糸とたて糸との間やよこ糸とよこ糸の間に位置し、たて糸とよこ糸を目どめ剤で接着させなくともよい。目どめ剤は扁平なたて糸やよこ糸の幅全体に線状に配置していると、表面張力、熱風の通過やクリンプ・インタージェンジによる糸幅の細幅化を防ぐことが出来るのである。
【００６１】
また、本発明において、目どめ剤はポリマー単独ではなく、低熱収縮性の補助糸にポリマーが被覆されている形態であってもよい。
【００６２】
このような形態のものは、低熱収縮性の補助糸にポリマーからなる繊維糸をカバーリング手段によって巻回し、たとえば、強化繊維糸のたて糸やよこ糸と引き揃えて使用して織物を作製した後、ポリマー繊維の融点以上に加熱・溶融することによって、補助糸にポリマーが被覆された目どめ織物を製造できる。
【００６３】
また、目どめ剤となる低融点のポリマーが鞘でより融点の高いポリマーが芯となっている、たとえば鞘が１６０℃〜２００℃程度の融点を有する低融点ポリエステルポリマーで芯が２６０℃程度の融点を有する高融点ポリエステルポリマーや、鞘が９０℃〜１５０℃程度の融点を有するポリエチレンの低融点ポリマーで芯が１６０℃〜１７５℃程度の融点を有するポリプロピレンの高融点ポリマーなどの芯鞘型のマルチフィラメント糸やモノフィラメント糸を強化繊維糸のたて糸やよこ糸と引き揃えて使用した織物を作製した後、低融点ポリマーの融点以上でかつ高融点ポリマーの融点以下に加熱・溶融することによって、補助糸にポリマーが被覆された目どめ織物を製造できる。
【００６４】
低熱収縮性の補助糸としては、１００℃における乾熱収縮率が１．０％以下のもので、好ましくは０．１％以下のものである。このような補助糸としてはガラス繊維糸やポリアラミド繊維糸などが好ましく、補助糸の繊度は５０デニールから８００デニール以下と細い糸が好ましい。
【００６５】
なお、芯鞘型のポリマー糸の乾熱収縮率は一般に大きいので、低融点ポリマーを加熱して溶融させる際、芯のポリマー糸が溶融せず繊維状に残って収縮するので、織物幅が狭くなり、織糸が蛇行するという問題が発生する。したがって、あらかじめ熱処理などで低収縮化し、乾熱収縮率を１．０％以下にしたものを使うとよい。
【００６６】
このように、目どめ剤としてのポリマーが低熱収縮性の補助糸に被覆されている形態であると、補助糸の周囲に目どめ剤が確実に存在することになるから、扁平なたて糸やよこ糸の幅全体に線状に確実に配置・接着することになり、湿式プリプレグ加工の際の糸幅の細幅化を、目どめ剤がポリマー単独の場合よりも完全に防ぐことができる。
【００６７】
また、目どめの方法として、低融点ポリマーの目どめ剤からなる不織布、またはフイルムを強化繊維織物の少なくとも片面に配置し、目どめ剤の融点以上に加熱してポリマー溶融し、加圧することによって強化繊維織物のたて糸およびよこ糸を糸幅全体にわたって接着していることで、扁平な織糸の幅全体にわたって繊維の位置を固定することもできる。フイルムにおいては、たとえば低融点ポリマーからなるポリ塩化ビニリデン、共重合ナイロン、共重合ポリエステル、ポリエチレン、ポリプロピレンなどのフイルムであり、厚みが０．０２ｍｍ以下の薄いフイルムが好ましい。フイルムの形態としては、全面均一な通常のフイルムの他、孔空きフイルムであってもよい。このような不織布は、たとえば低融点のポリマーを溶融してオリフィスから紡出し、オリフィスの両側から噴射される高速加熱流体で牽引細化して捕集面でウエブ形成される、いわゆるメルトブロー方式やフイラメント群を紡糸し、紡出フイラメントを開繊分散させてウエブ形成される、いわゆるスパンボンド方式であってよく、とくに限定するものではない。
【００６８】
このようにすることにより、目どめ剤を用いた場合と同じように、湿式プリプレグ加工工程において、溶剤の量が多くて樹脂粘度が小さい間は繊維同士の接着力が弱い場合においても、低融点ポリマーの目どめ剤からなる不織布、またはフイルムを強化繊維織物の少なくとも片面に配置することで織糸の幅方向の拘束できるのである。
【００６９】
このような本発明に係る強化繊維織物の湿式プリプレグの製造方法に用いる熱硬化性樹脂には、エポキシ樹脂、不飽和ポリエステル樹脂、ビニルエステル樹脂やフェノール樹脂などが用いられる。なかでも、本発明の製造方法は、フェノール樹脂による湿式プリプレグの製造法として好ましい。
【００７０】
本発明の湿式プリプレグ加工工程の一実施態様を図３に示した。基本構成は、前述の図１に示したのと同等の構成である。図３において、下部に設置し樹脂バス２６に、溶剤で希釈した溶液２７を入れ、この樹脂バス２６にロール状に巻かれた織物２１を１．５ｍ／分〜５ｍ／分程度の速度で引き出しながら浸漬し、織物の繊維間に樹脂を含浸させ、これを、十分な長さの乾燥ゾーンを有し、頂部に回転ロール２８を付けた縦型乾燥炉２９に通す。なお、織物の種類、乾燥速度、乾燥温度、樹脂の種類、溶剤の種類や樹脂付着量によっても異なるが、縦型乾燥炉２９の高さとしては８ｍ〜１５ｍ、樹脂含浸織物の上昇部と下降部で乾燥されるから、乾燥ゾーンの長さとしては、乾燥炉の高さの２倍、つまり１６ｍ〜３０ｍ程度が適当である。
【００７１】
次に、樹脂バス２６通過後回転ロール２８まで直線的に溶液の付着した織物２１を立ち上がらせ、織物の上り側の壁面３０の吹出し口３１、３２から温度Ａ、Ｂの熱風を織物面に直角方向に吹き付けて、ある程度溶剤を乾燥させた後、次に回転ロール２８に通して織物２１の進行方向を反転させ、下り側の壁面３３の吹出し口３４、３５からも温度Ｃ、Ｄの熱風を織物面に直角方向に吹き付けて残りの溶剤を乾燥させる。なお、壁面における熱風吹出し口が上り側の壁面３０および下り側の壁面３３で各々２〜４分割し、各々の吹出し口からの熱風温度が異なるようにして、溶剤の乾燥状態を制御出来るようにしておくと好ましい。また、織物の上昇部と下降部の乾燥温度が変更できるように縦型乾燥炉２９の中央部に、織物面と並行するようにセパレータ３６を取り付けておくと、各乾燥ゾーンの温度を正確に設定することが出来る。
【００７２】
溶剤を乾燥した織物を離形紙３７を挟みながら巻き取ることによって湿式加工法によるプリプレグが得られるのである。
【００７３】
なお、溶剤を乾燥するにあたり、少なくとも乾燥工程における乾燥ゾーンの前半の熱風温度が溶剤の、２種類以上の溶剤を混合する場合は沸点が最も低い溶剤の沸点以下であることが好ましい。ただし、沸点が最も低い溶剤の混合溶剤に占める割合が１０％未満であるなど、その悪影響が殆ど顕在化しない場合は無視してもかまわない。最も低い溶剤の沸点を超えると溶剤が乾燥する際、織物に付着した、樹脂を希釈した溶液が発泡し、この泡生成の力が、扁平糸織物のたて糸とよこ糸の交錯による織糸の拘束が緩やかであり、また糸束は無撚糸束内で繊維同士による交絡もないから、織糸の繊維配列を乱し、織糸の扁平状態を潰し、織物規格にもよるが、織糸が細幅化することがあるので、工程における、乾燥始めから乾燥ゾーンの少なくとも１／４までの間の熱風温度が溶剤の沸点以下であることが好ましい。ある程度溶剤の乾燥が進むと、樹脂の粘着性による繊維の拘束が向上するので、乾燥温度を上げることが出来る。
【００７４】
また、本発明の湿式プリプレグの製造法として、溶剤を乾燥させた後、織物プリプレグを離形フイルムまたは離形紙に挟むなどして、樹脂がロールに付着しないようにしながら８０℃〜１５０℃に加熱したカレンダロールで線圧が１．０ｋｇ／ｃｍ〜５０ｋｇ／ｃｍの状態で加圧しながら、供給速度１ｍ／分〜５ｍ／分程度で通すと、織糸が扁平状である、交錯点数が少ない、また織糸が無撚であることもあって、たて糸およびよこ糸の織糸の幅が拡がり、カバーファクターが１００％のプリプレグも得られる。
【００７５】
このような本発明に用いる強化繊維としても、ガラス繊維、ポリアラミド繊維、炭素繊維などの高強度・高弾性率の強化繊維であり、なかでも、引張弾性率が２００ＧＰａ以上、引張強度が４，５００ＭＰａ以上の炭素繊維は高強度・高弾性率であるのみならず、耐衝撃性にも優れ、また、樹脂がフェノール樹脂であると、炭素繊維は燃焼しないので耐火性にも優れる。また、使用する炭素繊維糸のフィラメント数は６，０００〜３０，０００本程度で、織物の炭素繊維目付は１４０ｇ／ｍ²〜４００ｇ／ｍ²程度が好ましい。
【００７６】
図４は、本発明に係る強化繊維織物の湿式プリプレグの製造方法で使用する扁平糸織物２１の他の一実施態様を示している。図４において、扁平なたて糸２２およびよこ糸２３からなる強化繊維織物の片面に低融点ポリマーの目どめ剤からなる不織布３８が接着され、不織布３８を構成する低融点ポリマー繊維３９が強化繊維織物の扁平なたて糸２２およびよこ糸２３の幅全体を該低融点ポリマー繊維３９で接着し、拘束している。
【００７７】
また、本発明では、本発明の製造法から得られる、糸幅が３〜２０ｍｍ、糸幅／糸厚み比が２０以上の無撚の扁平な強化繊維糸からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり２，５００〜２５，０００個でカバーファクターが９０％以上の強化繊維織物のプリプレグを特徴とする。
【００７８】
糸幅が３〜２０ｍｍ、糸幅／糸厚み比が２０以上の扁平な強化繊維からなり、たて糸とよこ糸の交錯点数が１平方メートル当たり２，５００〜２５，０００個と少ない交錯点数の織物プリプレグであるから、ドレープ性に優れる。また無撚の扁平な強化繊維糸からなる織物であるから、撚りによるくびれが無くて、全体的に目明き状態が均一な織物プリプレグとなる。また、カバーファクターが９０％以上であるから、強化繊維が均一に分散した織物プリプレグとなり、強化繊維が存在しない目明き部が小さいから、成形の際、目明き部にボイドが集中するようなことはなく、複合材料に成形した際の機械的特性が均一となる。
【００７９】
また、本発明では、本発明の製造法から得られる、たて糸およびよこ糸がフィラメント数が１２，０００本以上の炭素繊維束からなり、炭素繊維の重量が１平方メートルあたり１４０〜２４０ｇで、たて糸およびよこ糸の織り密度が同じ強化繊維織物のプリプレグであることを特徴とする。太い炭素繊維糸条で繊維の使用量の少ない、薄いプリプレグとなるので安価なプリプレグとなり、また、３０〜６０重量％の通常の樹脂付着量で薄いプリプレグとなるから、軽い成形品が得られる。
【００８０】
とくに、本発明の樹脂がフェノール樹脂であると、得られるＦＲＰは難燃性に優れるので好ましい。そして本発明のプリプレグは、また、たて糸とよこ糸の交錯点数が平方メートル当たり２，５００〜２５，０００個であるから、炭素繊維が存在しない目明き部個数が少なくなり、カバーファクターが９０％以上であるから目明き面積も小さくなり、強化繊維が炭素繊維であるから耐火性に優れる。このようなプリプレグは、とくに火災の際の炎が遮断されるので、とくに、航空機の、サイドウォール、ギャレイ、化粧室やフロアパネルを構成するサンドイッチ構造のＦＲＰ強化材として好ましく用いられる。また、電車やバスなどの内装材としても好ましく用いられる。
【００８１】
【実施例】
・織物Ａ
フイラメント数が６，０００本の無撚りの扁平状の炭素繊維束からなるたて糸に解舒撚りが入らないようにボビンからよこ取り解舒し、また、たて糸道においても撚りが入らないように扁平状態を規制し、よこ糸は、たて糸と同じ炭素繊維束を使用し、通常のたて取り解舒して、たて糸およびよこ糸密度が２．５本／ｃｍ、平組織で交錯点数が６２，５００個の、炭素繊維の重量が１平方メートルあたり２００ｇの織物Ａを作製した。この織物を構成するたて糸およびよこ糸の撚り数を測定したら、たて糸は零、よこ糸には解舒撚りが入り、撚り数は１０本の平均値で２．６回／ｍあった。撚りが入っている箇所は扁平状であった炭素繊維束がくびれて細くなっており、またよこ糸は、たて糸の扁平状とは異なり、全体的に細くなり、織物のカバーファクターは８９％であり、織物の目明き部も大きかった。
【００８２】
・織物Ｂ
フイラメント数が１２，０００本の炭素繊維束を使用し、織物Ａと同じ方法で、たて糸およびよこ糸密度が１．２０本／ｃｍ、平組織で交錯点数が１４，４００個の炭素繊維の重量が１平方メートルあたり１９３ｇの織物Ｂを作製した。なお、この織物では、織物を作製する際、よこ方向に目どめ剤としてアルコールに不溶性の、７０デニールの低融点共重合ナイロン糸が炭素繊維束のほぼ中央部に配置し、織機上で加熱溶融し、たて糸とよこ糸を接着させ、目どめ加工を行った。
作製した織物のたて糸およびよこ糸の撚り数を測定したら、たて糸は零、よこ糸には解舒撚りが入り、撚り数は１０本の平均値で３．２回／ｍあった。織物Ａと同様、撚りが入っている箇所は扁平状であった炭素繊維束がくびれて細くなっており、またよこ糸は、たて糸の扁平状とは異なり、全体的に細くなり、織物のカバーファクターは８０％であり、織物の目明き部も大きかった。
【００８３】
実施例１〜２
フェノール樹脂と溶媒としてメタノールを使用し、プリプレグの加工速度が１．５ｍ／分でプリプレグの樹脂重量割合Ｗ_Rがほぼ４０％となるようにフェノール樹脂をメタノールで希釈した溶液を準備した。
【００８４】
下部に設置し樹脂バスに、溶剤で希釈した溶液、この樹脂バスにロール状に巻かれた織物Ａを１．５ｍ／分の速度で引き出しながら浸漬して、織物の繊維間に樹脂を含浸させ、これを高さが１０ｍの頂部に回転ロールを付けた縦型乾燥炉に通した。樹脂バス通過後回転ロールまで直線的に溶液の付着した織物を立ち上がらせ、織物の上り側の壁面から熱風を織物面に直角方向に吹き付けて、ある程度溶剤を乾燥させた後、次に回転ロールに通して織物の進行を反転させ、下り側の壁面から熱風を織物面に直角方向に吹き付けて残りの溶剤を乾燥させ、この樹脂が含浸したプリプレグの温度が８０℃の状態で、１００℃に加熱したカレンダーロールに線圧が９．８ｋｇ／ｃｍで糸拡げを行い、離形紙を挟みながらプリプレグＡを巻き取った。同様に、織物Ｂを使用しプリプレグＢを作製した。加工後のプリプレグのカバーファクターを測定しその結果を表１に示した。
【００８５】
比較例１〜２
織物Ａ、Ｂを使用し、実施例の場合とは異なりカレンダーロールによる糸拡げ操作を行わず、その他は実施例と同様な条件にして、乾燥炉で溶剤を乾燥しプリプレグを作製し、離形紙を挟みながらプリプレグＡ、Ｂを各々巻き取った。加工後のプリプレグのカバーファクターを測定しその結果を表１に示した。
【００８６】
扁平状の炭素繊維糸条を使用して織物を作製したが、織物の製造過程でよこ糸に解舒よりが入ったこともあって、空隙部の大きくて、カバーファクターは織物Ａが８９％、織物Ｂが８０％と小さな織物であった。
【００８７】
これを従来の方法で湿式プリプレグ加工したところカバーファクターは織物Ａが８３％、織物Ｂが８２％のプリプレグとなり、いずれも元の織物よりもカバーファクターが小さくなり、またプリプレグ目明き部の１個当り平均面積も各々２．７２ｍｍ²、１２．５０ｍｍ²と大きなものであった（比較例１、２）。
【００８８】
一方、本発明の製造方法によってカレンダーロールによる糸拡げ操作を行ったプリプレグのカバーファクターは織物Ａが９９％、織物Ｂが９８％のプリプレグとなり、いずれも元の織物よりもカバーファクターが大幅に大きくなり、織物の糸拡げが十分行えているといえる。またプリプレグ目明き部の１個当り平均面積も各々０．１６ｍｍ²、１．３９ｍｍ²と小さくなり、炭素繊維が均一に分散し品位に優れたプリプレグとなった（実施例１、２）。
【００８９】
【表１】

【００９０】
実施例３〜１１、比較例３〜５
糸幅が６．５ｍｍ、糸幅／糸厚み比が６５の無撚の扁平な、フィラメント数が１２，０００本の炭素繊維束からなる、たて糸およびよこ糸密度が１．２５本／ｃｍ、平組織で交錯点数が１平方メートル当たり１５，６００個で炭素繊維の重量が１平方メートル当たり２００ｇの織物Ｃ、および前記強化繊維と同じ炭素繊維束によるたて糸およびよこ糸密度が１．００本／ｃｍ、平組織で交錯点数が平方メートル当たり１０，０００個で炭素繊維の重量が１平方メートル当たり１６０ｇの織物Ｄに、目どめ位置として、たて糸または／およびよこ糸の糸幅中央部に、目どめ剤としてアルコールに可溶性の低融点共重合ナイロン、低融点ポリエステル、ポリエチレンを用い、補助糸としてのガラス繊維糸ＥＣＥ２２５、１／０に目どめ剤を被覆した、織物幅が１００ｃｍの各目どめ織物を作製し、この織物を各々３０ｍの長さをロール状に巻いた。
【００９１】
また、織物Ｃ、Ｄに使用したと同じ炭素繊維束からなる、たて糸およびよこ糸密度が１．２０本／ｃｍ、平組織で交錯点数が１平方メートル当たり１４，４００個で炭素繊維の重量が１９３ｇ／ｍ²の織物にアルコールに不溶性の低融点ポリエステル繊維からなる繊維目付５ｇ／ｍ²の不織布を織物の片面に重ね合わせ、１６０℃に加熱したヒータ間を通過させ、不織布と織物を一体化させた織物Ｅ、およびたて糸およびよこ糸密度が１．００本／ｃｍ、平組織で交錯点数が１平方メートル当たり１０，０００個で炭素繊維の重量が１６０ｇ／ｍ²の織物に低融点ポリエステル繊維からなる繊維目付５ｇ／ｍ²の不織布を織物の片面に重ね合わせ織物Ｆを作製し、この織物を織物Ｃ、Ｄと同じく各々３０ｍの長さをロール状に巻いた。
【００９２】
湿式プリプレグ加工の樹脂としてはフェノール樹脂を使用し、これを溶剤Ａとしてメタノールで希釈した溶液、ＭＥＫで希釈した溶液、およびＭＥＫとメタノールを重量比で９０：１０の割合で混合した溶剤で希釈した溶液を作製した。なお、溶剤による樹脂の希釈は、プリプレグの加工速度が２．５ｍ／分の条件下でプリプレグの樹脂重量含有率がほぼ４０％となるように調整した。なお、実験に使用した織物の種類、目どめ剤の種類と溶剤の組み合せを表２、表３に示した。
【００９３】
下部に設置した樹脂バスに、溶剤で希釈した溶液を入れ、この樹脂バスにロール状に巻かれた織物を２．５ｍ／分の速度で引き出しながら浸漬して、織物の繊維間に樹脂を含浸させ、これを高さが１０ｍの頂部に回転ロールを付けた縦型乾燥炉に通した。樹脂バス通過後回転ロールまで直線的に溶液の付着した織物を立ち上がらせ、織物の上り側の壁面から温度Ａ、Ｂの熱風を織物面に直角方向に吹き付けて、ある程度溶剤を乾燥させた後、次に回転ロールに通して織物の進行方向を反転させ、下り側の壁面から温度Ｃ、Ｄの熱風を織物面に直角方向に吹き付けて残りの溶剤を乾燥させ、離形紙を挟みながらプリプレグを巻き取った。なお、織物の上昇部と加工部の乾燥温度が変更できるように縦型乾燥炉の中央部に、織物面と並行するようにセパレータを取り付けた。熱風温度は表２、表３に示した。
【００９４】
また、このプリプレグを１００℃に加熱したカレンダーロールに線圧が２０ｋｇ／ｃｍで、供給速度が１ｍ／分で通した。
【００９５】
上記湿式プリプレグ加工後およびカレンダー加工後のプリプレグのカバーファクターを測定しその結果を表２、表３、表４に示した。
【００９６】
【表２】

【００９７】
【表３】

【００９８】
【表４】

【００９９】
上記の実験による実施例３〜９および比較例３〜５から下記のことがいえる。Ａ．低融点ナイロンに溶解性のメタノールを溶剤にすると、織糸の扁平度が潰れ、糸幅が細くなることによってカバーファクターの小さなプリプレグとなるが（比較例３、４）、低融点ナイロンに対して非溶解性の溶剤であるＭＥＫを使用することによって、織物プリプレグのカバーファクターはプリプレグ加工前の織物に比べ若干小さくなることがあるものの、９０％以上の高いカバーファクターを有するプリプレグが得られた（実施例３、４、６、９）。
【０１００】
Ｂ．目どめ剤のポリマーに対して可溶性の溶剤であるメタノールを不溶性の溶剤であるＭＥＫに１０％程度混合しても、目どめ剤の効果があり、９０％以上の高いカバーファクターを有するプリプレグが得られた（実施例５）。
【０１０１】
Ｃ．目どめ剤のポリマーが低融点ポリエステルやポリエチレンの場合も、不溶性の溶剤であるメタノールを使用することによって、Ａ項と同様な効果があった（実施例７、８、１０、１１）。
【０１０２】
Ｄ．工程における、乾燥始めの熱風温度Ａ、Ｂを溶剤の沸点以上にすると織糸の扁平度が潰れ、カバーファクターが８０％の小さいプリプレグとなるが（比較例５）、乾燥ゾーンの１／２を熱風温度が溶剤の沸点以下の温度にすることによって、９５％以上の高いーカターファクターを有するプリプレグが得られた（実施例３）。
【０１０３】
Ｅ．プリプレグをカレンダー加工することによって、織糸が拡がり、カバーファクターが９４％〜９７％のプリプレグが１００％に向上し、完全に炭素繊維が分散したプリプレグが得られた（実施例３〜９）。
【０１０４】
【発明の効果】
以上詳述したように、本発明の強化繊維織物のプリプレグおよびその製造方法によれば、実質的に撚りのない強化繊維糸条からなり、たて糸とよこ糸の交錯点数が小さな織物に樹脂を含浸したのち、または樹脂を含浸しながら加圧ロールで糸拡げを行うから、糸が十分拡がり、カバーファクターの大きなプリプレグが得られる。
【０１０５】
また、本発明のプリプレグによれば、太い強化繊維糸条で薄いプリプレグとなるから安価で、軽い成形品が得られる。また織糸間の空隙によって形成されるプリプレグの目明き部がなくて、繊維が均一に分散しているから、ハニカムコキュアー成形法でハニカムサンドイッチ構造体を成形しても欠陥が入るようなことはなく、とくに航空機の内装材として優れた効果を奏する。
【０１０６】
また、本発明の強化繊維織物の湿式プリプレグの製造方法およびその方法により製造されたプリプレグによれば、扁平状の織糸からなる織糸同士の拘束度合いが弱い織物であっても、湿式プリプレグ加工で織糸が潰されるようなことはなく、織糸間の隙間がなくて、繊維が均一に分散した織物プリプレグが得られる。
【０１０７】
また、この織物プリプレグは、太い強化繊維糸で薄いプリプレグとなるから安価で、軽い成形品が得られる。また織糸間の隙間がなくて、繊維が均一に分散しているから、成形された複合材料の機械的特性が均一で、とくに内装材として優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の一実施態様に係るプリプレグの製造方法を示す、プリプレグ製造工程の概略縦断面図である。
【図２】本発明の一実施態様に係るプリプレグ作製用の強化繊維織物の部分平面図である。
【図３】本発明の別の実施態様に係るプリプレグの製造方法を示す、プリプレグ製造工程の概略縦断面図である。
【図４】本発明の他の一実施態様に係るプリプレグ作製用の強化繊維織物の平面図である。
【符号の説明】
１強化繊維織物
２樹脂バス
３溶液
４回転ロール
５縦型乾燥炉
６、９壁面
７、８、１０、１１熱風吹出し口
１２セパレータ
１３カレンダーローラ
１４離形紙
２１強化繊維織物
２２たて糸
２３よこ糸
２４、２５目どめ剤
２６樹脂バス
２７溶液
２８回転ロール
２９縦型乾燥炉
３０、３３壁面
３１、３２、３４、３５熱風吹出し口
３６セパレータ
３７離形紙
３８不織布
３９低融点ポリマー繊維[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prepreg of a reinforced fiber fabric used for forming a fiber reinforced plastic (hereinafter referred to as FRP) and a method for producing the prepreg.
[0002]
[Prior art]
FRP made by reinforcing reinforced fibers with resin, especially carbon fiber reinforced plastic (CFRP), is excellent in specific strength and specific elastic modulus. Therefore, it can be used as an aircraft structural material and interior material that can greatly improve fuel efficiency through weight reduction. It has been broken. However, since carbon fiber is expensive, the application site is limited even in an aircraft that is considered to have a large lightening effect.
[0003]
In particular, secondary structural materials such as aircraft flaps, fairings and ailerons, and interior materials such as restrooms, ceiling panels, undo panels and ceiling luggage compartments use honeycomb as the core material and CFRP as the skin material. Honeycomb sandwich structures are frequently used.
[0004]
The manufacturing method of these honeycomb sandwich structures is a so-called method in which the thermosetting resin of the prepreg and the bonding of the honeycomb and the CFRP are performed simultaneously by superimposing and heating and pressing a prepreg made of a carbon fiber fabric on the honeycomb. Molded by honeycomb cocure method. In the molding by the honeycomb cocure method, the curing of the resin and the bonding of the CFRP are simultaneously performed, so that the molding is greatly simplified. However, when forming, the prepreg at the location in contact with the honeycomb core is pressurized, but the portion not in contact with the core may not be pressurized, so there is a large feature where the carbon fiber does not partially exist in the prepreg If there is, a hole due to the lack of resin is opened in the CFRP skin of the portion that is not pressurized. As a countermeasure, a prepreg made of a woven fabric having a small gap formed by warps and wefts is used. Such a woven fabric is composed of thin carbon fiber yarns having a filament number of 3,000 filaments and is formed by warps and wefts. It is a thin fabric with a small gap and a small carbon fiber basis weight. However, since the carbon fiber yarn is thin, the production efficiency of the carbon fiber is poor, and the production speed of the woven fabric is slow, resulting in an expensive material.
[0005]
On the other hand, the thicker the yarn, the cheaper the reinforcing fiber yarn is. However, when a thin fabric having a small reinforcing fiber weight is manufactured from the thick yarn, the gap formed by the warp and the weft becomes a large fabric. . On the other hand, a flat yarn woven fabric that is thin using thick reinforcing fiber yarns, has a uniform fiber dispersion and a large cover factor, and a method for producing the same have been proposed in, for example, Japanese Patent Application Laid-Open No. 7-300739. Since this woven fabric is made of flat warp yarns and weft yarns and is a thin woven fabric, bending of the woven yarn is small, and the mechanical properties of the FRP are extremely excellent. However, this method requires a special device such as a yarn path to keep the flatness of the yarn, a weft supply system to prevent unwinding and twisting, and a flat device to grip the flat yarn. is there. Further, since weaving is performed while maintaining the flatness of the yarn, the flatness is crushed and thinned in the middle, and the gap formed by the warp and the weft is partially enlarged, which may be a defect.
[0006]
FRP is molded by various methods. As a method for obtaining high-performance FRP, the base material for molding is impregnated with a predetermined amount of sheet material such as woven fabric with B-stage resin containing a curing agent. Often used in the form of prepregs. As a manufacturing method of this prepreg, a so-called dry processing method in which a resin is processed into a film shape, combined with a sheet material, and heated and pressed to impregnate the resin into a sheet shape, and a solid resin or a B stage containing a curing agent There is a wet processing method in which a resin in a state is diluted with a solvent having a low boiling point such as methanol or MEK (methyl ethyl ketone), impregnated into a sheet material, and then dried. Compared with the wet processing method, the dry processing method has advantages such as no need for recovery of the solvent and management of the residual solvent, but it cannot be formed into a film depending on the type of resin. Further, depending on the kind of the curing agent, there are cases where it cannot be finely and uniformly dispersed in the resin, so a wet processing method is also used.
[0007]
As described above, since the reinforcing fiber is usually cheaper as the yarn becomes thicker, a flat yarn woven fabric having such a thin reinforcing fiber, uniform fiber dispersion and a large cover factor, and a method for producing the same are disclosed in, for example, It was proposed in Japanese Patent No. 7-300739. As described above, this woven fabric is composed of flat warp yarns and weft yarns, and is a thin woven fabric. Therefore, the woven yarn has a small bend (crimp), and the mechanical properties when FRP is used are extremely excellent. However, since the fabric is thick and has a small fabric basis weight, the fabric has a small number of intersections between the warp and the weft.
[0008]
Therefore, we previously proposed a woven fabric that was abruptly processed with a low-melting-point polymer as a countermeasure for form stability by prepreg processing. It was found that when the prepreg was actually processed with this woven fabric, a good fiber dispersion state of the woven fabric was ensured, that is, a prepreg having a large cover factor was obtained. However, in particular, in the woven state, the warp and weft yarns in a flat state where the warp yarns are sufficiently spread may be crushed in the prepreg processing process, and the woven yarn will become thin and become a mesh. Occurred. When the state of the prepreg processing is observed, in the case where the flattened state of the woven yarn occurs, the flat state of the woven yarn is maintained immediately after the woven fabric passes through the resin bath in which the resin is diluted with a solvent. However, after a while in the drying zone, the flat state began to collapse gradually. On the other hand, in the case where the flat state of the woven yarn was maintained with the fabric prepreg, the flat state was not crushed even when entering the drying zone. In other words, it has been found that the fine-meshing agent not only improves the handleability of the fabric in the process, but also plays a role of maintaining the flat state of the woven yarn of the flat yarn fabric during wet prepreg processing.
[0009]
[Problems to be solved by the invention]
  The object of the present invention is to solve the above-mentioned problems in the prior art.In addition, based on the above knowledge, the fiber dispersion is uniform, the woven yarn is flat, and a prepreg having a large cover factor can be produced, and the wet prepreg production method and the fiber dispersion produced by the method are uniform. It is to provide a prepreg having a large cover factor when the woven yarn is flat.
[0011]
[Means for Solving the Problems]
  Achieve the above objectivesForThe reinforcing fiber fabric of the present inventionWetThe prepreg manufacturing method is:It consists of untwisted flat reinforcing fiber yarns with a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The number of crossing points of warp and weft yarns is 2,500 to 25,000 per square meter. Using a reinforced fiber fabric with a cover factor of 90% or more,
(1) A low-heat-shrinkable auxiliary yarn in which a reinforcing agent made of a polymer is coated on a reinforcing fiber fabric is linearly arranged and adhered over the entire width of the weft yarn and / or the warp yarn,
(2) The reinforcing fiber fabric is immersed in a solution obtained by diluting a thermosetting resin with a solvent A in which at least 80% or more is insoluble in the polymer,
(3) Then, dry the solvent with hot air,
(4) Apply calendar roll
It consists of the method characterized by this.
[0012]
  Further, the method for producing a wet prepreg of a reinforced fiber fabric of the present invention comprises a non-twisted flat reinforcing fiber yarn having a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. Using woven fabrics with weft yarn crossing points of 2,500 to 25,000 per square meter and a cover factor of 90% or more,
(1) A nonwoven fabric composed of a polymer squeezing agent is disposed on at least one side of a reinforcing fiber fabric, and warp yarns and weft yarns of the reinforcing fiber fabric are bonded over the entire yarn width,
(2) The reinforcing fiber fabric is immersed in a solution obtained by diluting a thermosetting resin with a solvent A in which at least 80% or more is insoluble in the heat-fusible fiber,
(3) Then, dry the solvent with hot air,
(4) Apply calendar roll
It consists of the method characterized by this.
[0013]
  Moreover, the method for producing a wet prepreg of a reinforced fiber fabric according to the present invention comprises a non-twisted flat reinforcing fiber yarn having a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. Use a reinforced fiber fabric with 2,500 to 25,000 crossing points per square meter and a cover factor of 90% or more,
(1) A film made of a polymer squeezing agent is disposed on at least one side of a reinforcing fiber fabric, and warp and weft yarns of the reinforcing fiber fabric are used.Glues across the entire yarn width,
(2) At least 80% or more of the reinforced fiber fabric is a thermosetting resin.For heat-fusible filmDipping in a solution diluted with solvent A, which is insoluble,
(3) The solvent is then dried with hot airLet
(4) Apply calendar roll
It consists of the method characterized by this.
[0014]
Furthermore, the prepreg of the reinforced fiber fabric according to the present invention is a non-twisted flat reinforcing fiber yarn having a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more obtained by such a method. The number of intersections between the warp and the weft is 2,500 to 25,000 per square meter, and the cover factor is 90% or more.
[0016]
The reinforcing fiber fabric used in the production of the prepreg of the present invention is important because the number of crossing points of the warp yarn and the weft yarn influences the yarn expansion of the reinforcing fiber yarn of the fabric, and is in the range of 2,000 to 70,000 per square meter. It is preferable that it exists in. This is a normal reinforcing fiber fabric, for example, a carbon fiber basis weight of carbon fiber yarn of 3,000 filaments is 200 g / m.²The number of crossing points of the plain woven fabric is 250,000, which is extremely small. If the number of crossing points of the warp and weft yarns is small, the restraint state of the warp and weft yarns will be relaxed. For example, even in the case of a mesh-like fabric having a large gap formed by warp and weft yarns with a cover factor of about 70%, When impregnated, that is, in a state where reinforcing fibers are present in the resin, the reinforcing fibers move into the resin by the calender roll, and the width of the yarn can be expanded. If the number of crossing points is less than 2,000 per square meter, the restraint caused by the crossing of the warp and weft yarns will be weakened. Therefore, when the fabric passes through the roll in the prepreg process, it can be easily contacted with the guide roll. This is not preferable because the yarns are displaced and misaligned. On the other hand, when the number exceeds 70,000, the restraint due to the crossing of the warp and weft becomes strong, so that the yarn cannot be completely expanded, and the prepreg is filled with only the resin, leaving a conspicuous portion where no reinforcing fiber exists, which is not preferable. In addition, when the woven fabric has a cover factor of 70% or less, even if the yarn expansion operation is performed with a calender roll, the gap formed by the warp and weft yarn is too large and the yarn cannot be expanded until the space between adjacent yarns is filled. That is, it becomes difficult to obtain a prepreg having a large cover factor.
[0017]
In the present invention, the number of intersecting points of warp and weft per square meter means the number of points where warp and weft are interlaced. For example, in the case of a flat structure in which one warp and weft are alternately interlaced, [number of warps per square meter x number of wefts per square meter] is obtained, and 2/2 flats in which two warps and wefts are interlaced alternately. In the case of a structure, the number of warps per square meter / 2 × the number of wefts per square meter / 2.
[0018]
Here, the cover factor Cf is an element related to a void portion formed between the woven yarns of the woven fabric or a conspicuous portion where only the resin is filled in the void portion and no reinforcing fiber is present, and the area S on the woven fabric or the woven fabric prepreg.₁When the area is set, the area S₁The area of the void formed by the woven yarn or the area of the conspicuous portion filled with only the resin and free of reinforcing fibers is defined as S₂Then, it means the value defined by the following formula. In addition, when it is difficult to measure the area of the clear portion with the prepreg, when the light is applied from below the prepreg, the portion of the reinforcing fiber and the portion filled with only the resin without the reinforcing fiber can be clearly distinguished. .
Cover factor Cf = [(S₁-S₂) / S₁] × 100
[0019]
Further, in the production of the wet prepreg of the reinforced fiber fabric according to the present invention, first, the phenomenon that the flat state collapses was considered when the present invention was completed. That is, when considering the phenomenon that the flat state is crushed, it consists of flat reinforcing fiber yarns having a yarn width of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The 25,000 woven fabrics have an extremely small number of crossing points of 1/10 to 1/20 compared to ordinary woven fabrics, so that the restraint of the woven yarns due to the crossing of the warp and weft yarns is gentle, Because the yarn bundle is not entangled by fibers in the untwisted yarn bundle,
1) During wet prepreg processing, when such a fabric is immersed in a solution obtained by diluting a resin with a solvent and dried, the resin viscosity of the solution adhering to the fabric gradually increases, and the surface tension of the solution becomes flat. This works inside the width of the woven yarn, that is, in the direction of narrowing the width of the warp and weft, and the flat state of the woven yarn is crushed.
[0020]
2) Solvent drying in wet prepreg processing is performed with hot air to improve the drying efficiency, but warp yarn and weft yarn are passed by the air passing through the knitted fabric where the hot air is slightly present and passing through the knitted portion. A force acts in the direction of narrowing the width, and the flat state of the woven yarn is crushed.
[0021]
3) Further, in the vertical drying furnace, the upper fabric-impregnated fabric is subjected to its own weight and the weight of the solution in addition to the supply tension of the fabric, and the tension acts in the warp direction of the fabric. This tension straightens the warp yarns that have been crimped and increases the crimp of the weft yarns. During this change in the fabric structure, that is, crimp intergenge, the weft yarn acts in the direction of narrowing the warp yarn width.
[0022]
Moreover, when the wetting agent is linearly arranged on the reinforcing fiber fabric and the weft and / or warp yarn is bonded over the entire yarn width, the position of the fiber is fixed over the entire width of the flat woven yarn. It will be. When the solvent is dried to some extent in the wet prepreg process, the viscosity of the resin also increases, so the strength of bonding the fibers with the high-viscosity resin also increases. Even if the force to narrow the yarn width as described above works, the woven yarn The flat state of the fabric will not be crushed, but at least while the amount of solvent is large and the resin viscosity is low, the adhesive strength between the fibers is weak, and it is necessary to constrain the weaving yarn in the width direction with a squeezing agent I found out that
[0023]
In order to satisfy such conditions, the thermosetting resin may be diluted with a solvent A that is at least 80% insoluble in the polymer depending on the amount of polymer used as a sizing agent. Has been found to be insoluble in the squeeze polymer. If 80% or more of the solvent is insoluble in the polymer, that is, even if less than 20% of the solvent B is soluble in the polymer, the dissolution rate of the polymer is slowed, and the fabric passes through the resin bath and enters the drying zone. At least about 3 to 5 minutes, that is, until the solvent is dried to some extent and the viscosity of the resin is increased, the weaving agent remains restricted in the width direction of the weaving yarn, and the flat state of the weaving yarn is crushed It never happened. As the solvent insoluble in the polymer becomes less than 80% of the solvent, the flat state of the woven yarn begins to collapse gradually, the number of conspicuous parts in the prepreg begins to increase, the fiber dispersion becomes uneven, and the cover factor gradually decreases. It became a prepreg.
[0024]
The amount of the solvent as a diluent for the resin is determined by setting the amount of resin adhered to the fabric, and the solution viscosity may be set so that the resin amount of the prepreg is 30 to 60% by weight.
[0025]
In the present invention, it is not always necessary to use 100% of the solvent as the solvent A that is insoluble in the polymer of the sizing agent. In mixing the resin, the curing agent, the flame retardant, and other third components, the sizing is not necessary. Some amount of solvent B soluble in the polymer of the agent can be used.
[0026]
In the present invention, it is desirable that the sizing agent is a copolymer nylon having a melting point of about 100 to 140 ° C., and particularly when FRP is used, copolymer nylon, nylon 6 and copolymer nylon 12, nylon 6, nylon 66 And 610, nylon 6, nylon 12, 66, and 610 are preferable because of good adhesiveness of the resin, and because of their low melting point, it is easy to produce a knitted fabric. The melting point of the copolymer nylon and the solubility in the solvent are determined by the degree of disorder of the crystallinity of the nylon polymer during the copolymerization, depending on the combination and mixing ratio of the various nylon polymers. Depending on the type of copolymer nylon, methanol, etc. It becomes soluble or insoluble in alcohol. Therefore, the alcohol-soluble copolymer nylon solvent A is a non-alcohol solvent such as MEK, acetone or toluene.
[0027]
Here, the term “soluble” as used in the present invention means that a polymer yarn serving as a squeezing agent is placed in a beaker containing a solvent at 20 ° C., and the shape of the yarn disappears after standing for 10 minutes or becomes a lump or dissolves into a yarn. The state in which the traces of the yarn disappear is soluble, and the state in which the shape of the yarn is maintained is insoluble.
[0028]
In the present invention, methanol as a resin diluent is inexpensive, has a low boiling point, and is easy to dry during prepreg processing. Therefore, an alcohol solvent such as methanol is used as the diluent. A low melting point polyester made of copolymerized polyester or insoluble copolymerized nylon can be used as a stopping agent. The copolyester is composed of aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and naphthalene dicarboxylic acid, and / or alicyclic rings such as hexahydroterephthalic acid and hexahydroisophthalic acid. Is a copolymer ester containing a predetermined amount of aliphatic dicarboxylic acids and aliphatic and alicyclic diols such as diethylene glycol, propylene glycol, and paraxylene glycol, and adding oxyacids such as parahydroxybenzoic acid as desired. For example, there is a polyester obtained by adding and copolymerizing terephthalic acid and ethylene glycol with isophthalic acid and 1,6-hexanediol.
[0029]
The sizing agent in the present invention is preferably the above copolymer nylon or low melting point polyester, but other than the above, a low melting point polymer such as polyethylene or polypropylene can be used.
[0030]
The snooping agent does not essentially form an FRP matrix resin, and it may be completely different depending on the type of resin used. Therefore, the amount used is preferably as small as possible. 5-15g / m²The range of is preferable. 0.5g / m²If it is less than this, the restraint in the width direction of the flat weaving yarn becomes weak, and it is not possible to prevent the weaving yarn from being narrowed during wet prepreg processing. 15g / m²Exceeding the value may reduce the mechanical properties of FRP. 0.5-15g / m²If it is in the range, it is possible to prevent the weaving yarn from being narrowed, and the mechanical properties of the FRP are not deteriorated so much.
[0031]
Further, in the present invention, the amount of polymer per one line arranged in a linear manner is important because the setting agent prevents the weaving yarn from being narrowed. The amount of the polymer as the squeezing agent is preferably in the range of 0.2% by weight to 2% by weight with respect to the reinforcing fiber yarn.
[0032]
In addition, the linear arrangement of the squeezing agent used in the present invention is effective when the squeezing agent is in the form of a thread as described above. However, it may be in the form of a nonwoven fabric in which the fibers are randomly arranged in the surface direction.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
A method for producing a prepreg according to an embodiment of the present invention is shown in FIG. In FIG. 1, a solution 3 diluted with a solvent is placed in a resin bath 2 installed at the bottom, and a fabric 1 wound in a roll shape is drawn out on the resin bath 2 at a speed of about 1.5 m / min to 5 m / min. Then, the resin is impregnated between the fibers of the woven fabric, and this is passed through a vertical drying furnace 5 having a sufficiently long drying zone and having a rotating roll 4 at the top.
[0034]
Next, after passing through the resin bath, the fabric on which the solution adheres linearly rises up to the rotating roll, and hot air is blown in a direction perpendicular to the fabric surface from the outlets 7 and 8 of the wall surface 6 on the upstream side of the fabric. After drying, the fabric is then passed through the rotating roll 4 to reverse the direction of travel of the fabric, and hot air is blown in the direction perpendicular to the fabric surface from the outlets 10 and 11 of the downstream wall 9 to dry the remaining solvent. . The hot air outlets on the wall surface are divided into 2 to 4 parts on the upstream wall surface 6 and the downstream wall surface 9 so that the hot air temperature from each outlet port is different so that the drying state of the solvent can be controlled. It is preferable to keep it. Further, if the separator 12 is attached to the center of the vertical drying furnace 5 so as to be parallel to the fabric surface so that the drying temperature of the rising and falling portions of the fabric can be changed, the temperature of each drying zone can be accurately set. It can be set.
[0035]
The above is a method for producing a prepreg usually called a wet method, and there is no difference from a normal method. In the present invention, it is preferable to install a calender roller 13 composed of a pair of rollers in order to pressurize the prepreg which has been impregnated with the resin and has not yet cooled after leaving the drying zone to expand the weaving yarn. If the prepreg is warm, the resin is soft, so that it is easy to spread the yarn. The temperature of the prepreg during yarn expansion is preferably 50 to 150 ° C, and if it is less than 50 ° C, the resin becomes hard and yarn expansion becomes difficult. Further, since the curing of the resin is promoted when the temperature exceeds 150 ° C., it becomes difficult to manage the tack (adhesiveness) of the prepreg when the temperature is lowered to room temperature. If the temperature of the prepreg is high and the resin viscosity is high, the resin may adhere to the calendar roller. In such a case, it is possible to prevent the resin from adhering by coating the roller with silicone resin or fluorine resin, and before the prepreg enters the calender roller, the mold is impregnated with, for example, silicone resin from the upper and lower surfaces. By supplying the paper 14 and preventing the prepreg from directly contacting the roller, it is possible to prevent the resin from adhering to the roller. When the prepreg temperature is low and it is difficult to expand the yarn, the yarn can be expanded by a calender roller heated to 50 to 150 ° C. Alternatively, the resin-impregnated prepreg can be wound up once, and the prepreg cooled to room temperature can be preheated to 50 to 150 ° C. and heated with a calender roller while being heated.
[0036]
From the viewpoint of preventing fiber damage due to the calender roll, it is preferable that about 1 to 6% of the solvent remains in the resin of the prepreg after drying, and the resin adhering to the prepreg is softened. The pressure of the prepreg by the calender roller is preferably about 1 kg / cm to 50 kg / cm because the resin is soft. When the linear pressure is less than 1 kg / cm, although the solvent remains and the resin is soft and the yarn width is easy to expand, the yarn expansion is incomplete, and the void formed by the crossing of the warp and weft yarns can be filled with reinforcing fibers. This part cannot be made clear and the cover factor does not increase, and even if the cover factor increases, the part that remains clear remains and does not form a uniform prepreg. On the other hand, when the linear pressure exceeds 50 kg / cm, the number of crossing points of the warp and weft of the fabric is small, and the weft of the fabric prepreg may meander.
[0037]
The linear pressure referred to here is a value obtained by dividing the total load (kg) acting on the roller by the width (cm) of the fabric passing through the calender roll.
[0038]
Note that the pressing by the calendar roller may be performed by sandwiching a resin-impregnated fabric prepreg or a fabric and a resin film between one roller and a flat plate, or may be sandwiched between two rollers. The roller or flat plate may be made of metal or a combination of metal and rubber. The diameter of the roller is usually about 20 to 300 mm.
[0039]
If the cover factor of the reinforcing fiber fabric used in the present invention is 70% or more, it can be processed into a prepreg having a high cover factor by expanding the yarn by the prepreg manufacturing method of the present invention, but the cover factor is not necessarily 90 to 90. The fabric need not be 100% high and the cover factor may be 70 or more and less than 90%. A special device for maintaining the flatness of the warp and weft is required to produce a thin fabric having a small number of intersections between the warp and the weft and a cover factor of 90% or more. If the woven fabric is less than 1%, the woven fabric can be manufactured at a low cost because the woven fabric can be manufactured by a normal weaving operation.
[0040]
The warp yarns and weft reinforcing fiber yarns constituting the woven fabric of the present invention are in a state where there is substantially no twist, that is, about 4 times / m when unwinding and unwinding the yarn. May be. According to the method for producing a prepreg of the present invention, the yarn is spread with a calendar roller, so that the prepreg having a sufficiently large cover factor can be obtained. Preferably, the warp yarns and weft reinforcing fiber yarns constituting the woven fabric of the present invention have zero twists and the multifilaments are arranged substantially in parallel, so that the yarn can be spread more uniformly. preferable. When the reinforcing fiber yarn is twisted, it is necessary to expand the narrowed portion of the yarn due to twisting, and there are more severe conditions in terms of prepreg quality, such as increasing the pressure of the calendar roller. Although necessary, it is preferable that the yarn is untwisted under mild conditions because the twist of the yarn is zero.
[0041]
The reinforcing fiber used in the present invention is a high-strength, high-elastic modulus reinforcing fiber such as glass fiber, polyaramid fiber, carbon fiber, etc. Among them, the tensile elastic modulus according to JIS R7601 method is 200 GPa or more, and the tensile strength However, carbon fibers of 4,500 MPa or more have not only high strength and high elastic modulus, but also excellent impact resistance, and if the resin is a phenol resin, the carbon fibers do not burn, and therefore are excellent in nonflammability.
[0042]
In the case where the reinforcing fiber is a carbon fiber, from the viewpoint of reducing the number of crossing points of the warp and weft of the fabric, facilitating the expansion of the yarn by a calender roller, and producing a thin fabric prepreg, the carbon fiber yarn The number of filaments is 6,000 to 24,000. Conventionally, the thickness of the yarn is 2 to 8 times that of the 3,000 filament carbon fiber yarn used for aircraft applications, so the productivity in producing the carbon fiber is improved and the cost is reduced. If the number of filaments of the carbon fiber yarn exceeds 24,000, the number of crossing points of the warp yarn and the weft yarn is reduced in a thin fabric, which is not preferable because the fabric is misaligned in the prepreg process and the quality of the prepreg is lowered. .
[0043]
In the present invention, when the fabric is misaligned in the prepreg process, the intersection of the warp yarn and the weft yarn can be bonded with a sizing agent. From the viewpoint of carrying out squeezing with a small amount of squeezing agent at a low cost, a low melting point polymer such as copolymerized nylon, copolymerized polyester, polyethylene, and polypropylene is preferred. Among them, copolymerized nylon is preferably used because it has good adhesion to carbon fibers, and can be used in a slight amount, and also has good adhesion to the matrix resin constituting FRP. These low-melting-point polymer yarns are inserted into the fabric simultaneously with the warp yarns and / or weft reinforcing fiber yarns, heated above the melting point of the polymer on a loom, and the polymer is melted to obtain a reinforced reinforcing fiber fabric. Therefore, the squeezing treatment of the reinforcing fiber fabric can be performed at a low cost.
[0044]
In addition, as another method for closing the woven fabric in the prepreg process, a nonwoven fabric or film made of a low melting point polymer squeezing agent is placed on at least one side of the reinforcing fiber woven fabric to make the mesh close. The position of the fiber is fixed over the entire width of the flat weaving yarn by bonding the warp and weft of the reinforcing fiber fabric over the entire width of the yarn by heating it above the melting point of the agent to melt the polymer and applying pressure. You can also.
[0045]
In this case as well, low melting point heat-fusible fibers such as polyvinylidene chloride, copolymer nylon, copolymer polyester, polyethylene, and polypropylene are used at low cost and with a small amount of fiber basis weight or film basis weight. It is preferable that Among these, copolymerized nylon is preferably used because it has good adhesion to carbon fibers and can be awakened with a slight fiber basis weight and also has good adhesion to the matrix resin constituting FRP.
[0046]
As described above, the snooping agent does not essentially form a matrix resin of FRP, and depending on the type of resin used, it is quite different, so the amount used should be as small as possible. Well, 0.5-15g / m²The range of is preferable. Within this range, sufficient agitation is possible and the mechanical properties of the FRP are not significantly reduced.
[0047]
As the resin used in the present invention, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, or a phenol resin is used.
[0048]
Further, the present invention is characterized by a prepreg of a reinforced fiber fabric obtained from the production method of the present invention, wherein the number of crossing points of warp and weft is 2,000 to 70,000 per square meter and the cover factor is 97% or more. And Compared to conventional reinforced fiber fabrics, the number of crossing points is small, so it is excellent in deep drawability. Also, since the number of crossing points is small, the yarn spreads with a calender roll, so that it becomes a prepreg with a large cover factor, and even if several such prepregs are laminated on a honeycomb and molded by the honeycomb cocure method, the CFRP in a place where pressure is not applied Holes due to lack of resin are difficult to open in the skin. Further, since the cover factor is 97% or more, the obvious area of the reinforcing fiber fabric is reduced, and the reinforcing fiber is a carbon fiber, so that the fire resistance is excellent. Such a prepreg is particularly effective in blocking the flame during a fire.
[0049]
The warp yarn and the weft yarn are made of carbon fiber yarns of 6,000 filaments or more, the weft density of the warp yarn and the weft yarn is substantially the same, and the carbon fiber weight of the fabric is 140 to 240 g / m.²In the case of the prepreg of the fabric, the mechanical characteristics are the same in the length direction and the width direction, and the carbon fiber is cut in the direction of (0 ° / 90 °) and the prepreg is cut in the bias direction. By cross-stacking so as to be arranged in the direction of + 45 ° / −45 °), the mechanical characteristics can be easily made pseudo-isotropic. If the ratio of the weft density of warp and weft is within 20%, it may be considered that the weave density of warp and weft is almost the same. Carbon fiber fabrics are thin and light prepregs with a normal resin adhesion amount of 30 to 60% by weight, and a light sandwich structure can be obtained. In addition, since the number of crossing points of warp and weft yarns is less than 1/4 compared to conventional fabrics with the same plain structure with about 3,000 filaments of carbon fiber yarn and the same weight of carbon fiber, it is excellent in deep drawability. In addition, the carbon fiber yarn becomes thick and inexpensive.
[0050]
  The warp and weft yarns consist of carbon fiber yarns of 12,000 filaments or more, and the weaving density of the warp and weft yarnsSameThe carbon fiber weight of the fabric is 140-240 g / m²The number of crossing points is 1/16 or less than that of conventional carbon fiber fabrics, and the carbon fiber yarns are thicker than the 6,000 filament yarns. A thin and light prepreg is obtained, which is preferable.
Here, if the ratio of the weft density of the warp and the weft is within 20%, the weave density of the warp and the weftSameIt is the sameAnd seeYou can do it.
[0051]
Moreover, the average area of the crisp part of the fabric prepreg formed by warp and weft is 1.5 mm per piece.²Even if there is a clear part where the carbon fiber does not exist partially in the prepreg, it will be small, so even if honeycomb cocure molding is performed, a hole due to resin loss will open in the CFRP skin of the part that is not pressurized In other words, a honeycomb sandwich panel using CFRP having a smooth surface as a skin material is obtained.
[0052]
In the present invention, the average area of the aperture is defined as 100 apertures in which no carbon fiber is present even if the prepreg is filled in the corresponding portion of the void of the woven fabric formed by the crossing of the warp and weft. The average value of
[0053]
Further, according to the prepreg manufacturing method of the present invention, for example, the thickness of the reinforcing fiber yarn, the density of the warp and weft of the woven fabric, the fiber weight of the woven fabric, the amount of solvent before the calendar roller of the wet prepreg, the linear pressure of the roller and the roller hooking By optimizing the temperature of the prepreg at this time, the reinforcing fiber is opened and widened, and there is no conspicuous portion formed by the warp and the weft and a closed prepreg is obtained. Such a prepreg can completely block the flame in the event of a fire, and it is a sandwich structure formed by the honeycomb cocure method, which can completely prevent holes due to resin loss in the FRP skin, so quality It is suitable for aircraft parts with strict quality control.
[0054]
The closed state of the present invention refers to a state in which the number of voids formed by the warp and weft of the woven fabric before being processed into a prepreg is completely blocked by 2/3 or more, and is not completely blocked due to variation in conditions. Even if there is a portion, since the void area is small, substantially the same effect as in the closed state can be obtained.
[0055]
The structure of the woven fabric used in the present invention is not particularly limited, but a plain structure is preferable because the form is stable and misalignment in the prepreg processing step can be prevented.
[0056]
FIG. 2 shows an embodiment of the fine flat yarn fabric 21 used in the method for producing a wet prepreg of a reinforcing fiber fabric according to the present invention. The warp yarn 22 and the weft yarn 23 have a yarn width of 3. It is made up of untwisted flat reinforcing fiber yarns with a thread width / yarn thickness ratio of 20 or more, and the number of crossing points of the warp yarn 22 and the weft yarn 23 is 2,500 to 25,000 per square meter, and the cover factor Is over 90%.
[0057]
Here, the thickness of the yarn is in accordance with JIS-R3414, Section 5.4, and the spindle is gently rotated using a micrometer so that the measurement surface comes into light contact with the sample surface in parallel and the ratchet sounds three times. The scale is read when the thread is set, and the average value of N = 10 is defined as the thickness.
[0058]
In FIG. 2, in the two directions of the flat warp yarn 22 and the weft yarn 23, the clogging agent 24 and the clogging agent 25 are linearly bonded to the substantially central portion of the yarn width, and the warp yarn and the weft yarn are bonded at the crossing portion. However, the entire width of the flat warp and the weft is adhered and restrained with a setting agent.
[0059]
Here, it is not always necessary that the direction of the mesh is the two directions of the warp and the weft. Depending on the thickness of the weaving yarn, the weaving density, and the degree of restraint of the weaving yarn due to the weaving structure, at least if the wetting agent adheres to the weft yarn, the entire warp width must be restrained by the wetting agent. Therefore, it is possible to prevent a change in the fabric structure due to the tension acting in the warp direction of the fabric, that is, the narrowing of the warp yarn width due to the crimp intergenge.
[0060]
Further, it is not always necessary for the sizing agent to be located at the center of the yarn width. It may be shifted to the left and right with respect to the center of the weft yarn width, for example, between the warp yarn and the warp yarn of the reinforcing woven yarn or between the weft yarn and the weft yarn. In addition, when the warp and weft are bonded at the intersection, the crossing point is bonded and the shape of the fabric is stabilized, but this is not always necessary, it is located between the warp and the warp or between the weft and the weft. It is not necessary to bond the warp and weft with a sizing agent. When the squeezing agent is arranged linearly over the entire width of the flat warp or weft, it is possible to prevent the narrowing of the yarn width due to surface tension, the passage of hot air, and crimp intergenge.
[0061]
In the present invention, the squeezing agent may not be a polymer alone but may be a form in which a polymer is coated on a low heat shrinkable auxiliary yarn.
[0062]
In such a form, a fiber yarn made of a polymer is wound around a low heat-shrinkable auxiliary yarn by a covering means, and for example, a woven fabric is prepared by aligning with a warp yarn or a weft yarn of a reinforcing fiber yarn, By heating and melting to a temperature higher than the melting point of the polymer fiber, it is possible to produce a close woven fabric in which the auxiliary yarn is coated with the polymer.
[0063]
Also, the low melting point polymer used as a squeezing agent is a sheath and a polymer having a higher melting point is the core. For example, the sheath is a low melting point polyester polymer having a melting point of about 160 ° C. to 200 ° C. and the core is about 260 ° C. Core-sheath type, such as a high-melting polyester polymer having a melting point of 5 ° C or a low-melting polymer of polyethylene having a melting point of about 90 ° C to 150 ° C and a polypropylene having a melting point of about 160 ° C to 175 ° C. After producing a fabric using multifilament yarns and monofilament yarns aligned with warp yarns and weft yarns of reinforcing fiber yarns, it is supported by heating and melting above the melting point of the low melting point polymer and below the melting point of the high melting point polymer. A fine woven fabric with a polymer coated yarn can be produced.
[0064]
The auxiliary heat-shrinkable yarn has a dry heat shrinkage at 100 ° C. of 1.0% or less, preferably 0.1% or less. As such auxiliary yarns, glass fiber yarns, polyaramid fiber yarns, and the like are preferable, and fine yarns of auxiliary yarns having a fineness of 50 to 800 deniers are preferable.
[0065]
Since the core-sheath type polymer yarn generally has a large dry heat shrinkage rate, when the low melting point polymer is heated and melted, the core polymer yarn does not melt and remains in a fiber shape and shrinks, so the fabric width is narrow. Thus, the problem that the woven yarn meanders occurs. Therefore, it is preferable to use a material that has been previously shrunk by heat treatment or the like and has a dry heat shrinkage rate of 1.0% or less.
[0066]
In this way, when the polymer as the squeezing agent is covered with the low heat-shrinkable auxiliary yarn, the sizing agent is surely present around the auxiliary yarn. This ensures that the entire width of the weft yarn is linearly arranged and adhered, and the narrowing of the yarn width during wet prepreg processing can be completely prevented compared with the case where the setting agent is a polymer alone. .
[0067]
As a squeezing method, a non-woven fabric or film made of a low melting point polymer squeezing agent is placed on at least one side of the reinforcing fiber woven fabric and heated to a temperature higher than the melting point of the squeezing agent to melt the polymer. The position of the fibers can be fixed over the entire width of the flat woven yarn by bonding the warp yarn and the weft yarn of the reinforcing fiber fabric over the entire yarn width by pressing. As the film, for example, a film such as polyvinylidene chloride, copolymer nylon, copolymer polyester, polyethylene, and polypropylene made of a low-melting polymer, and a thin film having a thickness of 0.02 mm or less is preferable. As a form of the film, a perforated film may be used in addition to a normal film which is uniform over the entire surface. Such a nonwoven fabric is, for example, a so-called melt blow method or filament group in which a low-melting polymer is melted and spun from an orifice, and is pulled and thinned by a high-speed heating fluid sprayed from both sides of the orifice to form a web on a collecting surface. It is possible to use a spunbonding method in which the web is formed by spinning and dispersing the spinning filament, and there is no particular limitation.
[0068]
In this way, as in the case of using a squeezing agent, in the wet prepreg processing step, while the amount of solvent is large and the resin viscosity is small, even when the adhesive force between fibers is low, it is low. By arranging a nonwoven fabric or film composed of a melting point polymer melting agent on at least one side of the reinforcing fiber fabric, it is possible to constrain the weaving yarn in the width direction.
[0069]
Epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, and the like are used as the thermosetting resin used in the method for producing a wet prepreg of a reinforced fiber fabric according to the present invention. Especially, the manufacturing method of this invention is preferable as a manufacturing method of the wet prepreg by a phenol resin.
[0070]
One embodiment of the wet prepreg processing step of the present invention is shown in FIG. The basic configuration is the same as that shown in FIG. In FIG. 3, a solution 27 diluted with a solvent is placed in a resin bath 26 installed at the bottom, and the fabric 21 wound in a roll shape is pulled out at a speed of about 1.5 m / min to 5 m / min. Then, the resin is impregnated between the fibers of the woven fabric, and this is passed through a vertical drying furnace 29 having a sufficiently long drying zone and having a rotary roll 28 on the top. The height of the vertical drying furnace 29 is 8 to 15 m, and the rising and lowering portions of the resin-impregnated fabric are different depending on the type of fabric, drying speed, drying temperature, type of resin, type of solvent and amount of resin attached. Therefore, the length of the drying zone is suitably twice the height of the drying furnace, that is, about 16 to 30 m.
[0071]
Next, after passing through the resin bath 26, the fabric 21 to which the solution adheres linearly rises up to the rotary roll 28, and hot air at temperatures A and B is perpendicular to the fabric surface from the outlets 31, 32 of the wall surface 30 on the upstream side of the fabric. Then, the solvent is dried to some extent, and then passed through the rotary roll 28 to reverse the traveling direction of the fabric 21, and hot air of temperature C and D is also blown from the

outlets

34 and 35 of the lower wall surface 33. Spray the fabric surface at right angles to dry the remaining solvent. The hot air outlets on the wall surface are divided into 2 to 4 by the upstream wall surface 30 and the downstream wall surface 33, respectively, so that the hot air temperature from each outlet port is different so that the drying state of the solvent can be controlled. It is preferable to keep it. In addition, if the separator 36 is attached to the central portion of the vertical drying furnace 29 so as to be parallel to the fabric surface so that the drying temperature of the fabric rising and falling portions can be changed, the temperature of each drying zone can be accurately set. It can be set.
[0072]
A prepreg obtained by a wet processing method is obtained by winding the solvent-dried woven fabric with the release paper 37 interposed therebetween.
[0073]
In drying the solvent, the hot air temperature at least in the first half of the drying zone in the drying step is preferably not more than the boiling point of the solvent having the lowest boiling point when mixing two or more solvents. However, if the ratio of the solvent having the lowest boiling point to the mixed solvent is less than 10%, such as when the adverse effect is hardly manifested, it may be ignored. When the boiling point of the lowest solvent is exceeded, when the solvent dries, the resin-diluted solution that adheres to the fabric foams, and this force of foam formation is constrained by the weaving of the warp yarn by wefting and wefting of the flat yarn fabric. Since the yarn bundle is loose and there is no entanglement between fibers in the untwisted yarn bundle, the fiber arrangement of the woven yarn is disturbed, the flat state of the woven yarn is crushed, and the woven yarn is narrow, although it depends on the textile standard. Therefore, it is preferable that the hot air temperature in the process from the beginning of drying to at least 1/4 of the drying zone is equal to or lower than the boiling point of the solvent. When the solvent is dried to some extent, the fiber restraint due to the adhesiveness of the resin is improved, so that the drying temperature can be raised.
[0074]
In addition, as a method for producing the wet prepreg of the present invention, after drying the solvent, the fabric prepreg is sandwiched between a release film or release paper, and the resin is prevented from adhering to the roll at 80 ° C. to 150 ° C. While passing through a heated calender roll with a linear pressure of 1.0 kg / cm to 50 kg / cm while passing at a supply speed of about 1 m / min to 5 m / min, the woven yarn is flat, and the number of crossing points is small. Also, since the woven yarn is non-twisted, the width of the warp and weft yarn is expanded, and a prepreg having a cover factor of 100% can be obtained.
[0075]
Such reinforcing fibers used in the present invention are also high-strength and high-elastic modulus reinforcing fibers such as glass fiber, polyaramid fiber, and carbon fiber, and in particular, the tensile elastic modulus is 200 GPa or more and the tensile strength is 4,500 MPa. The above carbon fibers not only have high strength and high elastic modulus, but also have excellent impact resistance, and if the resin is a phenol resin, the carbon fibers do not burn and thus have excellent fire resistance. The number of filaments of the carbon fiber yarn used is about 6,000 to 30,000, and the carbon fiber basis weight of the woven fabric is 140 g / m.²~ 400g / m²The degree is preferred.
[0076]
FIG. 4 shows another embodiment of the flat yarn fabric 21 used in the method for producing a wet prepreg of a reinforcing fiber fabric according to the present invention. In FIG. 4, a nonwoven fabric 38 made of a low melting point polymer squeezing agent is bonded to one side of a reinforcing fiber fabric made of flat warp yarn 22 and weft yarn 23, and the low melting point polymer fiber 39 constituting the nonwoven fabric 38 is made of the reinforcing fiber fabric. The entire widths of the flat warp yarn 22 and the weft yarn 23 are bonded and restrained by the low melting point polymer fiber 39.
[0077]
Further, in the present invention, it is composed of a non-twisted flat reinforcing fiber yarn having a yarn width of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more obtained from the production method of the present invention, and the number of crossing points of the warp yarn and the weft yarn is It is characterized by prepregs of reinforced fiber fabrics with 2,500 to 25,000 pieces per square meter and a cover factor of 90% or more.
[0078]
A woven prepreg consisting of flat reinforcing fibers with a yarn width of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The number of crossing points of warp and weft yarns is as low as 2500 to 25,000 per square meter. There is excellent drape. Moreover, since it is a woven fabric made of flat non-twisted reinforcing fiber yarns, there is no constriction due to twisting, and a woven prepreg having a uniform overall visibility is obtained. In addition, since the cover factor is 90% or more, a woven prepreg in which reinforcing fibers are uniformly dispersed is obtained, and since there are small portions where no reinforcing fibers are present, voids are not concentrated on the portions where they are formed. The mechanical properties when molded into a composite material become uniform.
[0079]
In the present invention, the warp and weft obtained from the production method of the present invention are made of carbon fiber bundles having a filament number of 12,000 or more, and the weight of the carbon fiber is 140 to 240 g per square meter. Weave densitySameIt is characterized by being a prepreg of a reinforced fiber fabric. A thick carbon fiber yarn makes a thin prepreg with a small amount of fiber used, so that it becomes an inexpensive prepreg, and a thin prepreg with a normal resin adhesion amount of 30 to 60% by weight makes it possible to obtain a light molded product.
[0080]
In particular, when the resin of the present invention is a phenol resin, the obtained FRP is preferable because it is excellent in flame retardancy. In the prepreg of the present invention, the number of intersections between the warp and the weft is 2,500 to 25,000 per square meter. Therefore, the number of conspicuous portions where no carbon fiber is present is reduced, and the cover factor is 90% or more. As a result, the area is small, and the reinforced fiber is carbon fiber, so it has excellent fire resistance. Such a prepreg is particularly preferably used as an FRP reinforcing material having a sandwich structure that constitutes a side wall, a galley, a restroom, and a floor panel of an aircraft, since the flame at the time of fire is cut off. It is also preferably used as an interior material for trains and buses.
[0081]
【Example】
・ Textile A
The warp yarn is composed of 6,000 filaments of untwisted flattened carbon fiber bundles. The warp yarn is unwound and unwound from the bobbin so that it does not get twisted. The condition is regulated, and the weft yarn uses the same carbon fiber bundle as the warp yarn, and the normal warp yarn is unwound and the density of the warp yarn and weft yarn is 2.5 / cm, and the number of crossing points is 62,500 in a flat structure. Fabric A having a carbon fiber weight of 200 g per square meter was produced. When the number of twists of the warp yarn and the weft yarn constituting this woven fabric was measured, the warp yarn was zero, the weft yarn was untwisted, and the average number of twists of 10 was 2.6 times / m. Where the twist is in, the carbon fiber bundle that was flat was narrowed and thinned, and the weft was thin overall, unlike the warp flat, and the cover factor of the fabric was 89% The visible area of the fabric was also large.
[0082]
・ Textile B
Using carbon fiber bundles with 12,000 filaments and the same method as fabric A, the weight of carbon fiber with warp and weft density of 1.20 / cm, plain structure and number of intersections of 14,400 193 g of fabric B was prepared per square meter. In this woven fabric, a 70 denier low-melting point copolymer nylon yarn, which is insoluble in alcohol as a setting agent in the weft direction, is arranged in the center of the carbon fiber bundle and heated on the loom. After melting, the warp yarn and the weft yarn were bonded to each other, and crushing was performed.
When the number of warps and wefts of the produced fabric was measured, the warp was zero, the weft was untwisted, and the average number of ten twists was 3.2 times / m. Like the fabric A, the twisted portion of the twisted carbon fiber bundle is narrowed and the weft yarn is thin overall, unlike the flat shape of the warp, and the cover factor of the fabric. Was 80%, and the conspicuous part of the fabric was also large.
[0083]
Examples 1-2
Using phenol as the solvent and methanol as the solvent, the prepreg processing speed is 1.5 m / min and the prepreg resin weight ratio W_RWas prepared by diluting a phenolic resin with methanol so as to be approximately 40%.
[0084]
A solution diluted with a solvent and a fabric A wound in a roll shape in this resin bath are dipped while being pulled out at a speed of 1.5 m / min to impregnate the resin between the fabric fibers. This was passed through a vertical drying furnace having a rotating roll on the top having a height of 10 m. After passing through the resin bath, the fabric on which the solution adheres linearly rises up to the rotating roll, blows hot air from the wall surface on the upstream side of the fabric in a direction perpendicular to the fabric surface, and after drying the solvent to some extent, The fabric progress is reversed, hot air is blown perpendicularly to the fabric surface from the wall surface on the down side to dry the remaining solvent, and the prepreg impregnated with this resin is heated to 100 ° C. at a temperature of 80 ° C. The calender roll was subjected to yarn expansion at a linear pressure of 9.8 kg / cm, and the prepreg A was wound up while sandwiching the release paper. Similarly, the prepreg B was produced using the fabric B. The cover factor of the prepreg after processing was measured, and the results are shown in Table 1.
[0085]
Comparative Examples 1-2
Unlike the case of the examples, the fabrics A and B are not subjected to the yarn spreading operation by the calender roll, and the other conditions are the same as in the example, and the solvent is dried in a drying furnace to prepare a prepreg. Each of the prepregs A and B was wound up while sandwiching the paper. The cover factor of the prepreg after processing was measured, and the results are shown in Table 1.
[0086]
Fabrics were made using flat carbon fiber yarns, but weaving was introduced into the weft yarns during the production process of the fabrics. The gap was large and the cover factor was 89% for fabric A. The fabric B was as small as 80%.
[0087]
When this was wet prepreg processed by the conventional method, the cover factor was 83% for fabric A and 82% for fabric B, both of which had a smaller cover factor than the original fabric, and per cover of the prepreg opening. Each average area is also 2.72mm²12.50mm²(Comparative Examples 1 and 2).
[0088]
On the other hand, the cover factor of the prepreg subjected to the yarn spreading operation by the calender roll by the manufacturing method of the present invention is 99% for the fabric A and 98% for the fabric B, both of which have a significantly larger cover factor than the original fabric. Therefore, it can be said that the yarn is sufficiently expanded. Also, the average area per piece of prepreg opening is 0.16mm each.²1.39mm²As a result, the carbon fibers were uniformly dispersed and the prepreg was excellent in quality (Examples 1 and 2).
[0089]
[Table 1]

[0090]
Examples 3-11, Comparative Examples 3-5
Non-twisted flat with a yarn width of 6.5 mm and a yarn width / thickness ratio of 65, comprising 12,000 filaments of carbon fiber, warp and weft yarn density of 1.25 / cm, plain structure The number of crossing points is 15,600 per square meter and the carbon fiber weight is 200 g per square meter, and the warp and weft density is 1.00 / cm with the same carbon fiber bundle as the reinforcing fiber. Soluble in alcohol as a squeezing agent in fabric D with 10,000 crossings per square meter and carbon fiber weight of 160 g per square meter, in the center of warp or / and weft yarn width Of low melting point copolymer nylon, low melting point polyester, polyethylene, and glass fiber yarn ECE225 as auxiliary yarn, 1/0 coated with a sizing agent , The fabric width to produce each eye time fabric 100 cm, wound length of each 30m The fabric in roll form.
[0091]
Further, the density of the warp and weft is 1.20 pieces / cm, the number of crossing points is 14,400 pieces per square meter, and the weight of the carbon fiber is 193 g / cm. m²5 g / m of fabric weight consisting of low melting point polyester fiber insoluble in alcohol in woven fabrics²A non-woven fabric is laminated on one side of the woven fabric, passed through a heater heated to 160 ° C., and the non-woven fabric and the woven fabric are integrated with the woven fabric E, and the warp and weft density is 1.00 yarns / cm, and the number of crossing points in a plain structure. Is 10,000 pieces per square meter and the weight of carbon fiber is 160g / m²5 g / m of fabric weight made of low-melting polyester fiber on woven fabric²A non-woven fabric was laminated on one side of the woven fabric to prepare a woven fabric F, and the woven fabric was wound in a roll shape with a length of 30 m each, like the woven fabrics C and D.
[0092]
As a resin for wet prepreg processing, a phenol resin is used, which is diluted with methanol as a solvent A, a solution diluted with MEK, and a solvent in which MEK and methanol are mixed at a weight ratio of 90:10. A solution was made. The dilution of the resin with the solvent was adjusted so that the resin weight content of the prepreg was approximately 40% under the condition that the processing speed of the prepreg was 2.5 m / min. Tables 2 and 3 show the types of fabrics used in the experiments, the types of squeezing agents, and the combinations of solvents.
[0093]
A solution diluted with a solvent is placed in a resin bath installed at the bottom, and a fabric wound in a roll shape is immersed in the resin bath while being pulled out at a speed of 2.5 m / min, so that the resin is impregnated between the fibers of the fabric. Then, this was passed through a vertical drying furnace with a rotating roll attached to the top having a height of 10 m. After passing through the resin bath, the fabric with the solution linearly rising up to the rotating roll, spraying hot air of temperature A, B from the upside wall surface of the fabric in a direction perpendicular to the fabric surface, and drying the solvent to some extent, Next, it passes through a rotating roll to reverse the traveling direction of the fabric, blows hot air of temperature C and D from the downward wall surface in a direction perpendicular to the fabric surface to dry the remaining solvent, and holds the prepreg while sandwiching the release paper. Winded up. In addition, the separator was attached to the center part of the vertical drying furnace so as to be parallel to the fabric surface so that the drying temperature of the rising portion and the processing portion of the fabric could be changed. The hot air temperatures are shown in Tables 2 and 3.
[0094]
Further, the prepreg was passed through a calender roll heated to 100 ° C. at a linear pressure of 20 kg / cm and at a feed rate of 1 m / min.
[0095]
The cover factors of the prepreg after the wet prepreg processing and the calendar processing were measured, and the results are shown in Table 2, Table 3, and Table 4.
[0096]
[Table 2]

[0097]
[Table 3]

[0098]
[Table 4]

[0099]
The following can be said from Examples 3 to 9 and Comparative Examples 3 to 5 by the above experiments. A. When methanol, which is soluble in low-melting nylon, is used as a solvent, the flatness of the woven yarn is crushed and the yarn width is narrowed, resulting in a prepreg with a small cover factor (Comparative Examples 3 and 4). By using MEK, which is an insoluble solvent, the prepreg having a high cover factor of 90% or more was obtained, although the cover factor of the fabric prepreg may be slightly smaller than that of the fabric before prepreg processing ( Examples 3, 4, 6, 9).
[0100]
B. A prepreg having a high cover factor of 90% or more is effective even when about 10% of methanol, which is a solvent soluble in the polymer of the squeezing agent, is mixed with MEK, which is an insoluble solvent. Was obtained (Example 5).
[0101]
C. When the squeezing agent polymer was a low-melting point polyester or polyethylene, the same effect as in the item A was obtained by using methanol, which is an insoluble solvent (Examples 7, 8, 10, and 11).
[0102]
D. In the process, when the hot air temperatures A and B at the beginning of drying are set to be equal to or higher than the boiling point of the solvent, the flatness of the woven yarn is crushed and the cover factor is a small prepreg of 80% (Comparative Example 5). By setting the hot air temperature to a temperature below the boiling point of the solvent, a prepreg having a high-cutter factor of 95% or more was obtained (Example 3).
[0103]
E. By calendering the prepreg, the woven yarn spread, the prepreg with a cover factor of 94% to 97% was improved to 100%, and prepregs in which carbon fibers were completely dispersed were obtained (Examples 3 to 9).
[0104]
【The invention's effect】
As described above in detail, according to the prepreg of the reinforced fiber fabric of the present invention and the method for producing the prepreg, the fabric is made of reinforced fiber yarns that are substantially untwisted and impregnated with a resin in a woven fabric having a small number of crossing points of warp and weft yarns. Thereafter, the yarn is expanded with a pressure roll while impregnating the resin, so that the yarn is sufficiently expanded and a prepreg having a large cover factor can be obtained.
[0105]
Moreover, according to the prepreg of the present invention, a thin prepreg is formed with a thick reinforcing fiber yarn, so that a cheap and light molded product can be obtained. Also, there is no obvious part of the prepreg formed by the gaps between the weaving yarns, and the fibers are evenly dispersed.Therefore, even if the honeycomb sandwich structure is formed by the honeycomb cocure molding method, defects may enter. Not particularly, it has an excellent effect as an aircraft interior material.
[0106]
In addition, according to the method for producing a wet prepreg of a reinforced fiber fabric of the present invention and the prepreg produced by the method, wet prepreg processing is possible even if the degree of restraint between woven yarns composed of flat woven yarns is weak. Thus, the woven prepreg is obtained in which the woven yarn is not crushed and there is no gap between the woven yarn and the fibers are uniformly dispersed.
[0107]
Moreover, since this textile prepreg becomes a thin prepreg with thick reinforcing fiber yarns, it is inexpensive and a light molded product can be obtained. Further, since there are no gaps between the weaving yarns and the fibers are uniformly dispersed, the mechanical properties of the molded composite material are uniform, and particularly excellent as an interior material.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a prepreg manufacturing process showing a prepreg manufacturing method according to an embodiment of the present invention.
FIG. 2 is a partial plan view of a reinforcing fiber fabric for producing a prepreg according to an embodiment of the present invention.
FIG. 3 is a schematic longitudinal sectional view of a prepreg manufacturing process showing a prepreg manufacturing method according to another embodiment of the present invention.
FIG. 4 is a plan view of a reinforcing fiber fabric for producing a prepreg according to another embodiment of the present invention.
[Explanation of symbols]
1 Reinforced fiber fabric
2 Resin bath
3 Solution
4 Rotating roll
5 Vertical drying oven
6, 9 Wall surface
7, 8, 10, 11 Hot air outlet
12 Separator
13 Calendar Roller
14 Release paper
21 Reinforced fiber fabric
22 Warp
23 Weft
24, 25 Awakening agent
26 Resin bath
27 Solution
28 Rotating roll
29 Vertical drying oven
30, 33 wall surface
31, 32, 34, 35 Hot air outlet
36 separator
37 Release paper
38 Nonwoven fabric
39 Low melting point polymer fiber

Claims

It consists of untwisted flat reinforcing fiber yarns with a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The number of crossing points of warp and weft yarns is 2,500 to 25,000 per square meter. Using a reinforced fiber fabric with a cover factor of 90% or more,
(1) A low-heat-shrinkable auxiliary yarn in which a reinforcing agent made of a polymer is coated on a reinforcing fiber fabric is linearly arranged and adhered over the entire width of the weft yarn and / or the warp yarn,
(2) The reinforcing fiber fabric is immersed in a solution obtained by diluting a thermosetting resin with a solvent A in which at least 80% or more is insoluble in the polymer,
(3) Then, dry the solvent with hot air,
(4) Apply calendar roll
The manufacturing method of the wet prepreg of the reinforced fiber fabric characterized by the above-mentioned.

It consists of untwisted flat reinforcing fiber yarns with a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The number of crossing points of warp and weft yarns is 2,500 to 25,000 per square meter. Using a reinforced fiber fabric with a cover factor of 90% or more,
(1) A nonwoven fabric composed of a polymer squeezing agent is disposed on at least one side of a reinforcing fiber fabric, and warp yarns and weft yarns of the reinforcing fiber fabric are bonded over the entire yarn width,
(2) The reinforcing fiber fabric is immersed in a solution obtained by diluting a thermosetting resin with a solvent A in which at least 80% or more is insoluble in the heat-fusible fiber,
(3) Then, dry the solvent with hot air,
(4) Apply calendar roll
The manufacturing method of the wet prepreg of the reinforced fiber fabric characterized by the above-mentioned.

It consists of untwisted flat reinforcing fiber yarns with a yarn width in the range of 3 to 20 mm and a yarn width / yarn thickness ratio of 20 or more. The number of crossing points of warp and weft yarns is 2,500 to 25,000 per square meter. Using a reinforced fiber fabric with a cover factor of 90% or more,
(1) A film made of a polymer squeezing agent is disposed on at least one side of a reinforcing fiber fabric, and warp yarns and weft yarns of the reinforcing fiber fabric are bonded over the entire yarn width.
(2) The reinforcing fiber fabric is immersed in a solution obtained by diluting a thermosetting resin with a solvent A in which at least 80% or more is insoluble in the heat-fusible film,
(3) Then, dry the solvent with hot air,
(4) Apply calendar roll
The manufacturing method of the wet prepreg of the reinforced fiber fabric characterized by the above-mentioned.

In drying a solvent, in the drying step, the hot air temperature between the beginning of drying and at least 1/4 of the drying zone is not higher than the boiling point of the solvent, and the wet reinforced fiber fabric according to any one of claims 1 to 3. A method for producing a prepreg.

The method for producing a wet prepreg of a reinforced fiber fabric according to any one of claims 1 to 4, wherein the sizing agent is made of copolymer nylon soluble in alcohol, and the solvent A is made of a non-alcohol solvent.

The method for producing a wet prepreg of a reinforced fiber fabric according to any one of claims 1 to 4, wherein the squeezing agent is made of copolymer nylon insoluble in alcohol, and the solvent A is made of an alcohol solvent.

The method for producing a wet prepreg of a reinforced fiber fabric according to any one of claims 1 to 4, wherein the squeezing agent comprises a low-melting polyester, and the solvent A comprises an alcohol solvent.

The method for producing a wet prepreg of a reinforced fiber fabric according to any one of claims 1, 4 to 7, wherein the squeezing agent is attached to at least the weft yarn.

The method for producing a wet prepreg of a reinforcing fiber fabric according to any one of claims 1 to 8, wherein the resin is a thermosetting phenol resin.

The method for producing a wet prepreg of a reinforcing fiber fabric according to any one of claims 1 to 9, wherein the reinforcing fiber yarn is a carbon fiber yarn.

The manufacturing method of the wet prepreg of the reinforced fiber fabric in any one of Claims 1 thru | or 10 which is the range of 0.5-15 g / m < ² > of the usage-amounts of the said squeezing agent.

A warp yarn comprising a non-twisted flat reinforcing fiber yarn having a yarn width in the range of 3 to 20 mm and having a yarn width / yarn thickness ratio of 20 or more, obtained by the method according to any one of claims 1 to 11. A prepreg for a reinforcing fiber fabric characterized in that the number of crossing points of the weft yarn is 2,500 to 25,000 per square meter and the cover factor is 90% or more.

Warp and weft are made of carbon fiber bundle in the number of filaments more than 12,000, the weight of the carbon fibers is in the range of 140~240g / m ^2, weave density of warp and weft is the same, according to claim 12 Reinforced fiber fabric prepreg.

The prepreg of a reinforcing fiber fabric according to claim 12 or 13, wherein the resin is a phenol resin.