JP2004149980A - Carbon fiber strand and method for producing the same - Google Patents
Carbon fiber strand and method for producing the same Download PDFInfo
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- 229910052791 calcium Inorganic materials 0.000 claims abstract description 11
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Landscapes
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、樹脂の強化材等に好適な炭素繊維ストランド及びその製造方法に関し、更に詳述すればマトリックス樹脂に十分密着して引張強度及び剪断強さに優れた複合材料を製造することのできる炭素繊維ストランド及びその製造方法に関する。
【０００２】
【従来の技術】
炭素繊維は他の繊維と比較して強度や弾性率が高く、軽いという特徴を有するため、熱可塑性樹脂や熱硬化性樹脂をマトリックス樹脂とする複合材料の強化材として多用されている。この炭素繊維で強化した複合材料は、軽量で高強度であるので、航空宇宙産業を始めとし、各種の産業に広く利用されている。
【０００３】
この複合材料を製造する方法としては、中間基材であるプリプレグを用いて賦形成型する方法がある。更に、炭素繊維ストランドを用いて引抜成形、レジントランスファーモールディング（ＲＴＭ）法、フィラメント・ワインディング（ＦＷ）法、シート・モールディング・コンパウンド（ＳＭＣ）法、バルク・モールディング・コンパウンド（ＢＭＣ）法、ハンドレイアップ法などによって複合材料を製造できる。
【０００４】
複合材料の製造に用いられる熱可塑性のマトリックス樹脂としては、例えばポリアミド樹脂、ポリエステル樹脂、ポリオレフィン樹脂、ポリアセタール樹脂、ＡＢＳ樹脂等が挙げられる。
【０００５】
複合材料の製造に用いられる熱硬化性のマトリックス樹脂としては、例えばエポキシ樹脂、不飽和ポリエステル樹脂、ビニルエステル樹脂、フェノール樹脂等が挙げられるが、これらのうちでも特にエポキシ樹脂は耐熱性、物性等バランスの良い複合材料を与えるので好ましい。
【０００６】
エポキシ樹脂としては、ビスフェノールＡ型エポキシ樹脂、テトラグリシジルアミン、トリグリシジルアミン等の多官能エポキシ樹脂、ノボラック型エポキシ樹脂等が挙げられるが、特にビスフェノールＡ型エポキシ樹脂が接着性、物性等に優れ万能であるためマトリックス樹脂として広く使用されている。
【０００７】
炭素繊維は、上記各種樹脂のマトリックスとからなる繊維強化複合材料の強化材として利用されているが、炭素繊維の強化材としての高い物性を複合材料に生かすには、マトリックスとの接着性が重要である。
【０００８】
一般に炭素繊維は表面処理を施さないと、マトリックスに対して接着性が十分でなく、表面未処理の炭素繊維で複合化された材料は、剥離強度や剪断強度といった横方向（繊維軸方向）の物性が低い。
【０００９】
そのために通常炭素繊維には焼成後、電解酸化、薬液酸化、気相酸化といった酸化処理が施され、炭素繊維表面に酸素含有官能基を導入し、更にはサイジング処理が施され、マトリックスとの濡れ性や接着性を向上させている。
【００１０】
一方、これら酸化処理液を除去する工程や、酸化処理液・サイズ液希釈には一般的にイオン交換水・蒸留水・水道水（井戸水）等の処理水が用いられている。この処理水中に含まれている不純物の程度によっては、逆にマトリックス樹脂との接着性が低下してしまうことがある。
【００１１】
このように酸化処理によって得られる炭素繊維の表面特性について、特許文献１では炭素繊維最表面の官能基を特定することにより複合材料（コンポジット）における炭素繊維とマトリックス（母材）樹脂との接着強度が向上することが開示されているが、処理水の影響との組合せについては検討されていない。
【００１２】
またサイズ剤の付着状態の観察する手法については、特許文献２や特許文献３で行われているが十分なものではなかった。
【００１３】
【特許文献１】
特開平４−３６１６１９号公報（第２頁）
【特許文献２】
特開２００１−２４８０５９号公報（第３頁）
【特許文献３】
特開平４−４４５１１号公報（第３〜４頁）
【００１４】
【発明が解決しようとする課題】
本発明者は、上記問題について鋭意検討しているうち、マトリックス樹脂と炭素繊維との接着性向上の指標として、後述のサイズ剤の付着状態を規定することが重要であることを見出した。
【００１５】
即ち、炭素繊維の表面処理が施されてなる炭素繊維ストランドであって、炭素繊維表面における、Ｘ線光電子分光法（ＥＳＣＡ）により測定されるカルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）、イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）、酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）等の諸数値が所定範囲にある炭素繊維ストランドを強化材として用いた炭素繊維強化樹脂が、繊維軸方向の性能に優れ、且つ繊維垂直方向の破壊に影響が大きい層間剪断強度などに優れていることを知得した。
【００１６】
更に、炭素繊維ストランドの製造に際し、電解処理、水洗処理、及びサイズ剤付与処理の各表面処理に用いる水の電気伝導度（電導度）を所定範囲にすることなどにより、上記の強化材として優れた炭素繊維ストランドを得ることができることを知得し、本発明を完成するに到った。
【００１７】
従って、本発明の目的とするところは、上述した問題点を解決した、炭素繊維ストランド及びその製造方法を提供することにある。
【００１８】
【課題を解決するための手段】
上記目的を達成する本発明は、以下に記載するものである。
【００１９】
〔１〕 炭素繊維表面における、Ｘ線光電子分光法（ＥＳＣＡ）により測定されるカルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）が０．６％以下、イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）が０．６％以下、酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）が５〜３０％である炭素繊維ストランド。
【００２０】
〔２〕 炭素繊維表面にサイズ剤を有し、炭素繊維の１５８０〜１６００ｃｍ−１におけるラマン分光スペクトル強度のばらつきが下記式
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
で示すＣＶ値で４０％以下である〔１〕に記載の炭素繊維ストランド。
【００２１】
〔３〕 サイズ剤が、５０℃での粘度５〜１００Ｐａ・ｓのエポキシ樹脂系サイズ剤である〔１〕に記載の炭素繊維ストランド。
【００２２】
〔４〕 炭素繊維表面について、表面酸化処理、水洗処理、及びサイズ剤付与処理の表面処理を施す炭素繊維ストランドの製造方法であって、表面処理後の炭素繊維表面における、Ｘ線光電子分光法（ＥＳＣＡ）により測定されるカルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）が０．６％以下、イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）が０．６％以下、酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）が５〜３０％であり、表面処理後の炭素繊維の１５８０〜１６００ｃｍ−１におけるラマン分光スペクトル強度のばらつきが下記式
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
で示すＣＶ値で４０％以下である炭素繊維ストランドの製造方法。
【００２３】
〔５〕 表面酸化処理が電解処理であって、電解処理、水洗処理、及びサイズ剤付与処理の各表面処理に用いる水の電導度が５０μＳ／ｃｍ以下であるエポキシ樹脂系のサイズ剤を用いる〔４〕に記載の炭素繊維ストランドの製造方法。
【００２４】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００２５】
本発明の炭素繊維ストランドは、そのフィラメント数は１束当たり１０００〜５００００本が好ましい。
【００２６】
本発明の炭素繊維ストランドは、その炭素繊維表面に表面酸化処理、水洗処理、及びサイズ剤付与処理などの表面処理が施されている。炭素繊維表面における、Ｘ線光電子分光法（ＥＳＣＡ）により測定されるカルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）が０．６％以下、より好ましくは０．３％以下、イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）が０．６％以下、より好ましくは０．３％以下、酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）が５〜３０％、より好ましくは１０〜２５％である。
【００２７】
表面カルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）と、表面イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）が０．６％を超えると、繊維表面上の不純物の影響で、サイズ剤が炭素繊維１本１本に均一塗布され難くなり、その上のマトリックス樹脂も均一に含浸し難くなり、コンポジットの接着強度が低くなる。
【００２８】
また、表面酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）が５％未満の場合はマトリックス樹脂との接着性が劣るため好ましくない。一方、表面酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）が３０％を超える場合は炭素繊維自体の強度が低下するので好ましくない。
【００２９】
本発明では、マトリックス樹脂と炭素繊維との接着性向上の指標として、後述のサイズ剤の付着状態を規定することも重要であることを見出した。
【００３０】
この指標によると、本発明の炭素繊維ストランドは、サイズ剤を塗布した後の炭素繊維の１５８０〜１６００ｃｍ−１におけるラマン分光スペクトル強度のばらつきが下記式
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
で示すＣＶ値で４０％以下である事が好ましい。より好ましくは、３０％以下である。
【００３１】
ＣＶ値が４０％を超えた場合、サイズ剤の付着斑（むら）が大きくなり、結果的にマトリックスとの接着性が悪くなる。
【００３２】
本発明の炭素繊維ストランドは、その物性が上記範囲内にあれば、その製造方法としては、特に限定されるものではないが、例えば以下の製造方法により製造することができる。
【００３３】
前記炭素繊維ストランドを構成する炭素繊維は、原料としては特に限定するものではないが、ポリアクリロニトリル（ＰＡＮ）系炭素繊維、ピッチ系炭素繊維、レーヨン系炭素繊維等が例示できる。これらの炭素繊維のうち、取扱性能、製造工程通過性能に適したＰＡＮ系炭素繊維が特に好ましい。ここで、ＰＡＮ系炭素繊維は、アクリロニトリル構造単位を主成分とし、イタコン酸、アクリル酸、アクリルエステル等のビニル単量体単位を１０モル％以内で含有する共重合体を炭素繊維化したものである。
【００３４】
炭素繊維の表面酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）を前述の範囲にするためには、炭素繊維の製造工程において、炭素繊維化後、繊維表面の酸化処理（表面酸化処理）等の表面処理を施すことが好ましい。
【００３５】
かかる表面酸化処理は、液相処理、気相処理などによる表面処理を挙げることができる。本発明においては、生産性、処理の均一性、安定性等の観点から、液相電解表面処理（電解処理）が好ましい。
【００３６】
電解処理後の炭素繊維は、水洗処理され、次いでサイズ剤付与処理される。
【００３７】
炭素繊維のカルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）とイオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）を上記範囲にするためには、炭素繊維の製造工程において、電解処理、水洗処理、及びサイズ剤付与処理の各表面処理に使用する処理水の電導度が５０μＳ／ｃｍ以下の範囲が好ましい。より好ましくは２０μＳ／ｃｍ以下である。
【００３８】
処理水の電導度が５０μＳ／ｃｍを超えた場合、カルシウム濃度分率（Ｃａ２Ｓ／Ｃ１ｓ）とイオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）の両者、又はどちらか一方が上記範囲を外れてしまい、十分なコンポジットの接着強度が得られない。
【００３９】
本発明のサイズ剤付与処理に使用するサイズ剤においては、種類は特に限定されず、例えば、エポキシ樹脂、ウレタン樹脂、ポリエステル樹脂、ビニルエステル樹脂、ポリアミド樹脂、ポリエーテル樹脂、アクリル樹脂、ポリオレフィン樹脂、ポリイミド樹脂やその変性物が挙げられ、マトリックス樹脂により適したサイズ剤を選択する。またこれらは２種類以上を組み合わせて使用することも可能である。
【００４０】
サイズ剤の付与は、スプレー法、液浸法、転写法等、既知の方法を採択し得るが、汎用性、効率性、付与の均一性に優れるので、液浸法が好ましい。
【００４１】
炭素繊維ストランドをサイズ剤液に浸漬する際、サイズ剤液中に設けられた液没ローラ又は液浸ローラを介して、開繊と絞りを繰り返し、ストランドの芯までサイズ剤を含浸させることが好ましい。
【００４２】
サイズ剤付与処理は、アセトン等の溶剤にビニルエステルを溶解させた溶液中に炭素繊維を浸漬する溶剤法も可能であるが、乳化剤等を用い水系エマルジョン中に炭素繊維を浸漬するエマルジョン法が人体への安全性及び自然環境の汚染を防止する観点から好ましい。
【００４３】
本発明の炭素繊維ストランドは、５０℃での粘度が５〜１００Ｐａ・ｓ（５０〜１０００ポアズ）であるエポキシ樹脂系のサイズ剤液を塗布する事が好ましい。より好ましくは、５０℃での粘度が２０〜５０Ｐａ・ｓ（２００〜５００ポアズ）である。
【００４４】
５０℃での粘度が１００Ｐａ・ｓ（１０００ポアズ）を超えると、粘性が高いため、サイズ剤を塗布し乾燥した後の炭素繊維表面に均一に付着しにくくなる。５０℃での粘度が５Ｐａ・ｓ（５０ポアズ）より小さい場合、サイズ剤の耐熱性が低くなり、乾燥工程や、コンポジットの成型時に分解してガスが発生する等の問題がある。
【００４５】
また、炭素繊維ストランドの取扱性や、耐擦過性、耐毛羽性、含浸性を向上させるため、分散剤、界面活性剤等の補助成分を添加しても良い。さらに集束性などをより向上させるために、ポリウレタン、ポリエステル、ポリアミド樹脂など他の化合物を加えても良い。
【００４６】
サイズ剤付与処理後、炭素繊維ストランドは通常乾燥工程により、サイズ剤付与時の分散媒であった水の乾燥あるいは溶媒である溶剤の脱溶剤を行う。乾燥工程は乾燥炉を通過させる方法、過熱したローラーに接触させる方法等、既知の方法が採択し得る。乾燥温度は特に規定されないが、汎用的な水系エマルジョンの場合は通常８０〜２００℃に設定される。また、本発明においては、乾燥工程の後、２００℃以上の熱処理工程を経ることも可能である。
【００４７】
以下、実施例により本発明を更に具体的に説明する。
【００４８】
【実施例】
以下の実施例及び比較例に記載した条件により炭素繊維ストランドを作製した。なお、実施例及び比較例中のＸ線光電子分光法（ＥＳＣＡ）、ラマン分光法、炭素繊維ストランド強度、コンポジットの層間剪断強度（略語：ＩＬＳＳ）、面内剪断強さの諸物性値測定は次の方法に準拠した。
【００４９】
（１）Ｘ線光電子分光法（ＥＳＣＡ）
溶媒でサイズ剤などの付着物を除去した炭素繊維ストランドをカットしてステンレス製の試料支持台上に拡げて並べた後、光電子脱出角度を９０゜とし、Ｘ線源としてＭｇＫα１，２ を用い、試料チャンバー内を１×１０−６Ｐａの真空度に保った。測定時の帯電に伴うピークの補正として、まずＣ１ｓの主ピークの結合エネルギー値を２８４．６ｅＶに合わせた。
【００５０】
Ｃ１ｓピーク面積は、２８２〜２９６ｅＶの範囲で直線のベースラインを引くことにより求め、Ｃａ２ｓピーク面積は、３４４〜３５４ｅＶの範囲で直線のベースラインを引くことにより求め、Ｓ２ｐピーク面積は、１６５〜１７５ｅＶの範囲で直線のベースラインを引くことにより求め、Ｏ１ｓピーク面積は、５２８〜５４０ｅＶの範囲で直線のベースラインを引くことにより求めた。
【００５１】
Ｃａ２ｓ／Ｃ１ｓ、Ｓ２ｐ／Ｃ１ｓ、Ｏ１ｓ／Ｃ１ｓはそれぞれ、上記Ｃａ２ｓ、Ｓ２ｐ、Ｏ１ｓピーク面積とＣ１ｓピーク面積の比を、装置固有の感度補正値で割ることにより算出した原子数比で表した。なお、本実施例及び比較例では日本電子製ＪＰＳ−９０００ＭＸを用いて測定した。
【００５２】
（２）ラマン分光法
ラマン分光分析は、ジョバン−イーボン製 Ｔ６４００を用い、励起波長５１４．５ｎｍ（５１４５オングストローム）のＡｒ＋レーザーを用い、励起出力２０ｍＷ、ビーム径１μｍφ以下で、入射レーザー変更面は、繊維軸と平行に入射、散乱光は無偏光で測定した。得られたラマンスペクトルについて、バックグラウンドを引いた後、バンド分解を行い、１５８０〜１６００ｃｍ−１のラマンバンドのピーク高さを求めた。
【００５３】
測定点数については、個別の試験片を５個作製し、ランダムな位置でｎ＝２で測定し、合計５×２＝１０点を測定し、下記式
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
でＣＶ値を算出した。
【００５４】
（３）炭素繊維ストランド強度
ＪＩＳ Ｒ ７６０１に規定された方法により測定した。
【００５５】
（４）コンポジットの層間剪断強度（略語：ＩＬＳＳ）
フェノールノボラック型エポキシ樹脂（チバガイギー社製、商品名：ＥＰＮ１１３８）７０質量部、ビスフェノールＡ型エポキシ樹脂（ジャパンエポキシレジン社製、商品名：エピコート８３４）１２質量部、ビスフェノールＡ型エポキシ樹脂（ジャパンエポキシレジン社製、商品名：エピコート１００２）１８質量部の割合で混合した樹脂組成物に、更に硬化剤、促進剤を加え、プリプレグ用樹脂組成物を作製した。
【００５６】
この樹脂組成物をフィルムコーターにより、離型紙の上に塗布し、樹脂フィルムとした。この樹脂フィルム上にサイズ処理された炭素繊維ストランドを等間隔に引き揃え並べた後、加熱して樹脂を該炭素繊維ストランドに含浸させ、炭素繊維目付１５０ｇ／ｍ２、樹脂含浸率３７質量％のＵＤプリプレグを作製した。
【００５７】
上記にて作製したＵＤプリプレグを成型後の厚みが３ｍｍとなるように積層し、金型に入れ、１８０℃で２時間、０．６９ＭＰａ−Ｇａｕｇｅ（７ｋｇｆ／ｃｍ２−Ｇａｕｇｅ）の圧力で成型し、繊維が１方向に配列した炭素繊維強化成型板（ＣＦＲＰ板：コンポジット）を作製した。このＣＦＲＰ板のＩＬＳＳをＡＳＴＭ−Ｄ−２３４４に準拠し、室温にて測定を行った。
【００５８】
（５）面内剪断試験
ナイロン６（宇部興産社製ＵＢＥナイロン６ １０１３Ｂ）をマトリックス用樹脂として、樹脂浴（長さ：３００ｍｍ、幅：５０ｍｍ、高さ：８０ｍｍ、直径３０ｍｍの液浸ローラ×３個、出入口に直径３０ｍｍのガイドローラ設置）に適量投入した。
【００５９】
３０ｃｍ長に切断した炭素繊維ストランドを適度な本数、平行に束ね（以下サンプル束Ａとする）、両端を市販の炭素繊維ストランド（東邦テナックス社製ベスファイト、１２０００フィラメント、引張強度３９００ＭＰａ、引張弾性率２３５ＧＰａ）にて縛り固定した。
【００６０】
この内、片端に関しては固定に使用している市販の炭素繊維ストランド１束（以下誘導糸とする）は、予め樹脂浴（入口ガイドローラ→液浸ローラをジグザグに→出口ガイドローラ）、絞りガイド及び筒状の金型（内容 断面：１２．７ｍｍ×３．５ｍｍ、長さ３００ｍｍ）を通過させておいたものを用いた。樹脂浴は、フレキシブルリボンヒーターを用いて２４０℃に保温しておいた。
【００６１】
サンプル束Ａを樹脂浴入口ガイドローラ手前に樹脂浴長さ方向と平行にしておき、速度２０ｍ／ｈで、サンプル束Ａが金型内に収まるまで誘導糸を引っ張った後、誘導糸を切断、除去した。
【００６２】
尚、サンプル束Ａを形成する炭素繊維ストランドの本数は炭素繊維フィラメント断面積及び炭素繊維ストランドのフィラメント数により決めた（炭素繊維体積含有率Ｖｆが６０％になるように調整した）。
【００６３】
上記のサンプル束Ａが充填した金型を室温（２４℃）にて２４時間放置することでマトリックス樹脂を硬化させてコンポジット（成型物Ａ）を形成させた後、成型物Ａを離型した。離型した成型物ＡからＡＳＴＭ Ｄ ３８４６−７９に準拠した試験片を作製し、同規定に準拠して面内剪断試験（ｎ＝２）の測定をした。
【００６４】
実施例１
６０質量％の塩化亜鉛系水溶液を溶媒として、アクリロニトリル９７質量％、アクリル酸メチル３質量％、分子量７８０００、重合体濃度８質量％の溶液を紡糸原液として、孔数１２０００個のノズルを使用して、１０℃、２５質量％の塩化亜鉛系水溶液中に吐出して凝固させた。
【００６５】
該凝固糸を１５〜９５℃の温水中で洗浄しながら、トータル３．２倍の多段延伸を行い、水分率１７０質量％の水膨潤アクリル系繊維ストランドを得た。次に該水膨潤繊維にアミノシリコン系オイルを浴濃度２０ｇ／Ｌに調整し、ディップ式で塗布した。
【００６６】
次いで７０〜１５０℃のサクションドラム乾燥機で水分率が１質量％以下になるまで乾燥緻密化した。次いで、８０℃の熱水浴を通過した後、０．０７ＭＰａの飽和水蒸気中４．５倍の再延伸を行い、ケンス内に振込み、０．９デニール、２４０００本のプリカーサーストランドを得た。
【００６７】
このプリカーサーストランドを用いて、常法により２４０〜２７０℃の範囲内の温度勾配を有する熱風循環式耐炎化炉で４０分間連続的に耐炎化処理を行った。次いで、窒素気流中３００〜１３００℃の温度勾配を有する炭素化炉で５分間処理して、炭素繊維ストランドとした。得られた炭素繊維ストランドはイールド１．６３ｇ／ｍ、比重１．８０であった。
【００６８】
この炭素繊維ストランドについて、濃度１０ｇ／Ｌの硫安を電解液として、電気量２０クーロン／ｇで処理した。この電解処理を施された炭素繊維ストランドを続いて水洗し、１５０℃の加熱空気中で乾燥した。電解液の希釈水及び水洗水は電導度０．９μＳ／ｃｍのイオン交換水を用いた。
【００６９】
続いて、エポキシ変性ウレタン（大日本インキ化学工業株式会社製ＨＹＤＲＡＮ Ｎ３２０）、ポリオキシエチレン（１５）ラウリルグリシジルエーテル（松本油脂製薬株式会社製）、オクチルステアレート（新日本理化社製、エヌジェルブＯＳ）乳化物を表１のように配合し、濃度が３０ｇ／Ｌ、５０℃での粘度が４８Ｐａ・ｓのサイズ剤溶液を調製した。
【００７０】
サイズ剤溶液調製時の希釈水には電導度０．９μＳ／ｃｍのイオン交換水を用いた。このサイズ剤溶液を用い、浸漬法により炭素繊維ストランドにサイズ剤を付与し、１５０℃、６０秒で乾燥した。炭素繊維ストランドへのサイズ剤の付着量は１．１質量％であった。
【００７１】
このようにして得られた炭素繊維ストランドについて、Ｘ線光電子分光法（ＥＳＣＡ）による表面カルシウム濃度分率（Ｃａ２ｓ／Ｃ１ｓ）、表面イオウ濃度分率（Ｓ２ｐ／Ｃ１ｓ）及び表面酸素濃度分率（Ｏ１ｓ／Ｃ１ｓ）、１５８０〜１６００ｃｍ−１におけるラマン分光スペクトル強度のＣＶ値、ストランド強度、ＩＬＳＳ、並びに、面内剪断強さ等の各種物性値測定を行った。それら測定結果を表１に示す。
【００７２】
比較例１
処理水を表１に示す電導度のものに変化させた以外は実施例１と同様に、炭素繊維ストランドを作製し、この炭素繊維ストランドについて、各種物性値測定を行った。それら測定結果を表１に示す。
【００７３】
実施例２及び３、並びに、比較例２
サイズ剤としてビスフェノールＡ型エポキシ樹脂（ジャパンエポキシレジン社製エピコート８２８、１００２）を表１のように配合し、このサイズ剤配合物１００質量部をＰＯ／ＥＯポリエーテル２０質量部で乳化した表１に示す５０℃での粘度の水エマルジョンをサイズ剤溶液として使用すると共に、処理水を表１に示す電導度のものに変化させた以外は実施例１と同様に、炭素繊維ストランドを作製し、この炭素繊維ストランドについて、各種物性値測定を行った。それら測定結果を表１に示す。
【００７４】
比較例３
濃度１０ｇ／Ｌの硫安を電解液として、電気量４０クーロン／ｇで処理した点と処理水を表１に示す電導度のものに変化させた以外は実施例３と同様に、炭素繊維ストランドを作製し、この炭素繊維ストランドについて、各種物性値測定を行った。それら測定結果を表１に示す。
【００７５】
【表１】
表１の結果に示すように、実施例１〜３は何れも満足な結果が得られた。しかし、比較例１〜２はＩＬＳＳや熱可塑性マトリックス樹脂での面内剪断強さ等の性能で満足な結果が得られなかった。比較例３はストランド強度、ＩＬＳＳや面内剪断強さ等の性能で満足な結果が得られなかった。
【００７７】
【発明の効果】
本発明の炭素繊維ストランド及び本発明の製造方法によって得られる炭素繊維ストランドは、サイズ剤が均一に付与され、その上のマトリックス樹脂の含浸性も均一化される作用などにより、物性が優れた炭素繊維強化複合材料を得ることが可能である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a carbon fiber strand suitable for a resin reinforcing material and the like, and a method for producing the same. More specifically, it is possible to produce a composite material which is sufficiently adhered to a matrix resin and has excellent tensile strength and shear strength. The present invention relates to a carbon fiber strand and a method for producing the same.
[0002]
[Prior art]
Carbon fibers have high strength and elastic modulus as compared with other fibers and are light in weight. Therefore, carbon fibers are frequently used as a reinforcing material for a composite material using a thermoplastic resin or a thermosetting resin as a matrix resin. Since the composite material reinforced with carbon fiber is lightweight and high in strength, it is widely used in various industries including the aerospace industry.
[0003]
As a method of manufacturing this composite material, there is a method of forming and using a prepreg as an intermediate base material. Furthermore, pultrusion molding using carbon fiber strands, resin transfer molding (RTM), filament winding (FW), sheet molding compound (SMC), bulk molding compound (BMC), and hand lay-up A composite material can be manufactured by a method or the like.
[0004]
Examples of the thermoplastic matrix resin used for producing the composite material include a polyamide resin, a polyester resin, a polyolefin resin, a polyacetal resin, and an ABS resin.
[0005]
Examples of the thermosetting matrix resin used in the production of a composite material include an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, and the like. It is preferable because it gives a well-balanced composite material.
[0006]
Examples of the epoxy resin include bisphenol A type epoxy resins, polyfunctional epoxy resins such as tetraglycidylamine and triglycidylamine, and novolak type epoxy resins. In particular, bisphenol A type epoxy resins are excellent in adhesiveness, physical properties, etc. Therefore, it is widely used as a matrix resin.
[0007]
Carbon fiber is used as a reinforcing material for fiber-reinforced composite materials consisting of the above-mentioned various resin matrices.To make use of the high physical properties of carbon fiber reinforcing materials in composite materials, adhesion to the matrix is important. It is.
[0008]
In general, if the carbon fiber is not subjected to surface treatment, the adhesiveness to the matrix is not sufficient, and the material composited with the untreated surface carbon fiber has a transverse (fiber axis) direction such as peel strength or shear strength. Low physical properties.
[0009]
Therefore, carbon fibers are usually subjected to oxidation treatment such as electrolytic oxidation, chemical liquid oxidation, and gas phase oxidation after firing, to introduce oxygen-containing functional groups on the carbon fiber surface, and further subjected to sizing treatment to wet the matrix. It has improved properties and adhesion.
[0010]
On the other hand, treated water such as ion-exchanged water, distilled water, and tap water (well water) is generally used for the step of removing the oxidizing solution and the dilution of the oxidizing solution and the size solution. Depending on the degree of impurities contained in the treated water, the adhesiveness to the matrix resin may be reduced.
[0011]
Regarding the surface characteristics of the carbon fiber obtained by the oxidation treatment as described above, Patent Document 1 specifies the functional group on the outermost surface of the carbon fiber to determine the adhesive strength between the carbon fiber and the matrix (base material) resin in the composite material (composite). Is disclosed, but the combination with the effect of treated water is not studied.
[0012]
Further, a technique for observing the state of adhesion of the sizing agent is disclosed in Patent Document 2 or Patent Document 3, but is not sufficient.
[0013]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 4-361719 (page 2)
[Patent Document 2]
JP 2001-248059 A (page 3)
[Patent Document 3]
JP-A-4-44511 (pages 3-4)
[0014]
[Problems to be solved by the invention]
The present inventor has made intensive studies on the above problem and found that it is important to define the adhesion state of the sizing agent described below as an index for improving the adhesiveness between the matrix resin and the carbon fiber.
[0015]
That is, a carbon fiber strand on which surface treatment of carbon fiber has been performed, and a calcium concentration fraction (Ca 2s / C 1s ) and a sulfur concentration on the carbon fiber surface measured by X-ray photoelectron spectroscopy (ESCA). The carbon fiber reinforced resin using carbon fiber strands having various numerical values such as the fraction (S 2p / C 1s ) and the oxygen concentration fraction (O 1s / C 1s ) within a predetermined range as a reinforcing material has a performance in the fiber axial direction. It has been found that they are excellent in interlaminar shear strength and the like, which has a great influence on breaking in the vertical direction of the fiber.
[0016]
Further, in the production of carbon fiber strands, the electric conductivity (conductivity) of water used for each surface treatment of electrolytic treatment, washing treatment, and sizing agent imparting treatment is set to a predetermined range, and thus, it is excellent as the above-mentioned reinforcing material. It was found that a carbon fiber strand could be obtained, and the present invention was completed.
[0017]
Therefore, an object of the present invention is to provide a carbon fiber strand and a method for producing the same, which solve the above-mentioned problems.
[0018]
[Means for Solving the Problems]
The present invention that achieves the above object is as described below.
[0019]
[1] On the carbon fiber surface, the calcium concentration fraction (Ca 2s / C 1s ) measured by X-ray photoelectron spectroscopy (ESCA) is 0.6% or less, and the sulfur concentration fraction (S 2p / C 1s ) is A carbon fiber strand having an oxygen concentration fraction (O 1s / C 1s ) of 0.6% or less and 5 to 30%.
[0020]
[2] The carbon fiber has a sizing agent on the surface thereof, and the dispersion of Raman spectral intensity at 1580 to 1600 cm −1 of the carbon fiber is represented by the following formula: CV value (%) = (standard deviation of Raman spectral intensity) / (Raman spectroscopy) Average value of spectrum intensity) × 100
The carbon fiber strand according to [1], which has a CV value of 40% or less.
[0021]
[3] The carbon fiber strand according to [1], wherein the sizing agent is an epoxy resin-based sizing agent having a viscosity of 5 to 100 Pa · s at 50 ° C.
[0022]
[4] A method for producing a carbon fiber strand in which the surface of a carbon fiber is subjected to a surface treatment such as a surface oxidation treatment, a water washing treatment, and a sizing agent imparting treatment, wherein X-ray photoelectron spectroscopy ( The calcium concentration fraction (Ca 2s / C 1s ) measured by ESCA) is 0.6% or less, the sulfur concentration fraction (S 2p / C 1s ) is 0.6% or less, and the oxygen concentration fraction (O 1s / C 1s ) is 5 to 30%, and the variation of the Raman spectrum intensity at 1580 to 1600 cm −1 of the carbon fiber after the surface treatment is represented by the following formula: CV value (%) = (standard deviation of Raman spectrum intensity) / ( Average value of Raman spectrum intensity) × 100
A method for producing a carbon fiber strand having a CV value of 40% or less.
[0023]
[5] The surface oxidation treatment is an electrolytic treatment, and an epoxy resin-based sizing agent having an electric conductivity of water of 50 μS / cm or less used for each surface treatment of the electrolytic treatment, the water washing treatment, and the sizing agent imparting treatment is used [ [4] The method for producing a carbon fiber strand according to [4].
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0025]
The carbon fiber strand of the present invention preferably has a filament count of 1,000 to 50,000 per bundle.
[0026]
The carbon fiber strand of the present invention has been subjected to a surface treatment such as a surface oxidation treatment, a water washing treatment, and a sizing agent imparting treatment on the surface of the carbon fiber. The calcium concentration fraction (Ca 2s / C 1s ) measured by X-ray photoelectron spectroscopy (ESCA) on the carbon fiber surface is 0.6% or less, more preferably 0.3% or less, and the sulfur concentration fraction (S 2p / C 1s ) is 0.6% or less, more preferably 0.3% or less, and the oxygen concentration fraction (O 1s / C 1s ) is 5 to 30%, more preferably 10 to 25%.
[0027]
If the surface calcium concentration fraction (Ca 2s / C 1s ) and the surface sulfur concentration fraction (S 2p / C 1s ) exceed 0.6%, the sizing agent may be reduced to carbon fiber 1 due to the influence of impurities on the fiber surface. It becomes difficult to uniformly apply the resin to one of these, and it is difficult to uniformly impregnate the matrix resin thereon, and the adhesive strength of the composite becomes low.
[0028]
On the other hand, if the surface oxygen concentration fraction (O 1s / C 1s ) is less than 5%, the adhesion to the matrix resin is poor, which is not preferable. On the other hand, if the surface oxygen concentration fraction (O 1s / C 1s ) exceeds 30%, the strength of the carbon fiber itself decreases, which is not preferable.
[0029]
In the present invention, it has been found that it is also important to define the adhesion state of the sizing agent described below as an index for improving the adhesion between the matrix resin and the carbon fiber.
[0030]
According to this index, in the carbon fiber strand of the present invention, the dispersion of the Raman spectral spectrum intensity at 1580 to 1600 cm −1 of the carbon fiber after the application of the sizing agent is represented by the following formula CV value (%) = (Raman spectral spectrum intensity (Standard deviation) / (average value of Raman spectrum intensity) × 100
It is preferable that the CV value is 40% or less. More preferably, it is 30% or less.
[0031]
If the CV value exceeds 40%, uneven spots (unevenness) of the sizing agent increase, resulting in poor adhesion to the matrix.
[0032]
The carbon fiber strand of the present invention is not particularly limited as long as its physical properties are within the above-mentioned ranges, and can be manufactured by, for example, the following manufacturing method.
[0033]
The carbon fiber constituting the carbon fiber strand is not particularly limited as a raw material, but examples thereof include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber, and the like. Among these carbon fibers, PAN-based carbon fibers suitable for handling performance and production process passing performance are particularly preferable. Here, the PAN-based carbon fiber is obtained by converting a copolymer containing a acrylonitrile structural unit as a main component and a vinyl monomer unit such as itaconic acid, acrylic acid, or acrylic ester within 10 mol% into carbon fiber. is there.
[0034]
In order to make the surface oxygen concentration fraction (O 1s / C 1s ) of the carbon fiber fall within the above-mentioned range, in the carbon fiber production process, the surface of the fiber is oxidized (surface oxidation treatment) after the carbon fiber is formed. Preferably, a treatment is applied.
[0035]
Such a surface oxidation treatment may include a surface treatment such as a liquid phase treatment or a gas phase treatment. In the present invention, liquid phase electrolysis surface treatment (electrolysis treatment) is preferable from the viewpoint of productivity, uniformity of treatment, stability and the like.
[0036]
The carbon fiber after the electrolytic treatment is subjected to a water washing treatment and then a sizing agent applying treatment.
[0037]
In order to make the calcium concentration fraction (Ca 2s / C 1s ) and the sulfur concentration fraction (S 2p / C 1s ) of the carbon fiber within the above ranges, in the carbon fiber production process, electrolytic treatment, water washing treatment, and size The conductivity of the treated water used for each surface treatment in the agent application treatment is preferably in the range of 50 μS / cm or less. More preferably, it is 20 μS / cm or less.
[0038]
When the conductivity of the treated water exceeds 50 μS / cm, both the calcium concentration fraction (Ca 2S / C 1s ) and the sulfur concentration fraction (S 2p / C 1s ) are out of the above range. As a result, sufficient composite adhesive strength cannot be obtained.
[0039]
In the sizing agent used in the sizing agent application treatment of the present invention, the type is not particularly limited, for example, epoxy resin, urethane resin, polyester resin, vinyl ester resin, polyamide resin, polyether resin, acrylic resin, polyolefin resin, A sizing agent more suitable for the matrix resin is selected, such as a polyimide resin or a modified product thereof. These may be used in combination of two or more.
[0040]
Known methods such as a spray method, a liquid immersion method, and a transfer method can be adopted for applying the sizing agent, but the liquid immersion method is preferable because of excellent versatility, efficiency, and uniformity of application.
[0041]
When the carbon fiber strand is immersed in the sizing liquid, it is preferable to repeat opening and drawing through a liquid immersion roller or a liquid immersion roller provided in the sizing liquid to impregnate the sizing agent up to the core of the strand. .
[0042]
For the sizing agent application treatment, a solvent method in which carbon fibers are immersed in a solution in which vinyl ester is dissolved in a solvent such as acetone can be used.However, an emulsion method in which carbon fibers are immersed in an aqueous emulsion using an emulsifier or the like is used. It is preferable from the viewpoint of safety to natural environment and prevention of pollution of the natural environment.
[0043]
The carbon fiber strand of the present invention is preferably applied with an epoxy resin-based sizing liquid having a viscosity at 50 ° C. of 5 to 100 Pa · s (50 to 1000 poise). More preferably, the viscosity at 50 ° C. is 20 to 50 Pa · s (200 to 500 poise).
[0044]
If the viscosity at 50 ° C. exceeds 100 Pa · s (1000 poises), it is difficult to uniformly adhere to the carbon fiber surface after applying and drying the sizing agent because the viscosity is high. If the viscosity at 50 ° C. is less than 5 Pa · s (50 poise), there is a problem that the heat resistance of the sizing agent is low, and the sizing agent is decomposed during the drying step or the molding of the composite to generate gas.
[0045]
Further, auxiliary components such as a dispersant and a surfactant may be added in order to improve the handleability of the carbon fiber strand, the abrasion resistance, the fuzz resistance, and the impregnation. In order to further improve the convergence and the like, other compounds such as polyurethane, polyester, and polyamide resin may be added.
[0046]
After the sizing treatment, the carbon fiber strands are usually dried in a drying step to dry water serving as a dispersion medium at the time of sizing treatment or to remove a solvent as a solvent. As the drying step, a known method such as a method of passing through a drying furnace and a method of contacting with a heated roller can be adopted. The drying temperature is not particularly limited, but is generally set at 80 to 200 ° C. for a general-purpose aqueous emulsion. Further, in the present invention, after the drying step, a heat treatment step at 200 ° C. or more can be performed.
[0047]
Hereinafter, the present invention will be described more specifically with reference to examples.
[0048]
【Example】
Carbon fiber strands were produced under the conditions described in the following Examples and Comparative Examples. In the Examples and Comparative Examples, X-ray photoelectron spectroscopy (ESCA), Raman spectroscopy, carbon fiber strand strength, interlaminar shear strength of composite (abbreviation: ILSS), measurement of various physical properties such as in-plane shear strength are as follows. Method.
[0049]
(1) X-ray photoelectron spectroscopy (ESCA)
After cutting the carbon fiber strands from which the deposits such as the sizing agent were removed with a solvent and spreading and arranging them on a stainless steel sample support, the photoelectron escape angle was 90 °, and MgKα 1,2 was used as the X-ray source. The inside of the sample chamber was kept at a vacuum of 1 × 10 −6 Pa. As the correction of the peak due to the measurement time of the charging, it was first combined binding energy value of the main peak of C 1s to 284.6 eV.
[0050]
The C 1s peak area was determined by drawing a linear base line in the range of 282 to 296 eV, the Ca 2s peak area was determined by drawing a linear base line in the range of 344 to 354 eV, and the S 2p peak area was determined by: The O 1s peak area was determined by drawing a linear baseline in the range of 165 to 175 eV, and the O 1s peak area was determined by drawing a linear baseline in the range of 528 to 540 eV.
[0051]
Ca 2s / C 1s , S 2p / C 1s , and O 1s / C 1s are respectively obtained by dividing the ratio of the above-mentioned Ca 2s , S 2p , O 1s peak area and C 1s peak area by a sensitivity correction value unique to the apparatus. It was represented by the calculated atomic ratio. In addition, in this Example and the comparative example, it measured using JEOL Ltd. JP-9000MX.
[0052]
(2) Raman spectroscopy Raman spectroscopy was performed using T6400 manufactured by Joban-Evon, using an Ar + laser having an excitation wavelength of 514.5 nm (5145 Å), an excitation output of 20 mW, a beam diameter of 1 μmφ or less, and an incident laser changing surface. And incident parallel to the fiber axis, and scattered light was measured without polarization. After subtracting the background from the obtained Raman spectrum, band decomposition was performed to determine the peak height of the Raman band at 1580 to 1600 cm −1 .
[0053]
Regarding the number of measurement points, five individual test pieces were prepared, measured at n = 2 at random positions, and a total of 5 × 2 = 10 points were measured, and the following formula CV value (%) = (Raman spectral intensity) Standard deviation) / (average value of Raman spectral intensity) × 100
The CV value was calculated.
[0054]
(3) Carbon fiber strand strength Measured according to the method specified in JIS R 7601.
[0055]
(4) Interlaminar shear strength of composite (abbreviation: ILSS)
70 parts by mass of a phenol novolak type epoxy resin (manufactured by Ciba Geigy, product name: EPN1138), 12 parts by mass of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin, product name: Epicoat 834), bisphenol A type epoxy resin (Japan epoxy resin) (Co., Ltd., trade name: Epicoat 1002) A curing agent and an accelerator were further added to the resin composition mixed at a ratio of 18 parts by mass to prepare a resin composition for prepreg.
[0056]
This resin composition was applied on release paper with a film coater to obtain a resin film. After arranging the carbon fiber strands sized on this resin film at equal intervals, the resin is impregnated into the carbon fiber strands by heating. The carbon fiber strand has a carbon fiber weight of 150 g / m 2 and a resin impregnation rate of 37% by mass. A UD prepreg was prepared.
[0057]
The UD prepreg prepared above is laminated so that the thickness after molding becomes 3 mm, placed in a mold, and molded at 180 ° C. for 2 hours under a pressure of 0.69 MPa-Gauge (7 kgf / cm 2 -Gauge). A carbon fiber reinforced molded plate (CFRP plate: composite) in which fibers are arranged in one direction was produced. The ILSS of this CFRP plate was measured at room temperature in accordance with ASTM-D-2344.
[0058]
(5) In-plane shear test Nylon 6 (UBE Nylon 6 1013B manufactured by Ube Industries, Ltd.) was used as a matrix resin, and a liquid bath (length: 300 mm, width: 50 mm, height: 80 mm, diameter 30 mm) × 3 And a proper amount of the roller were installed at the entrance and exit.
[0059]
A suitable number of carbon fiber strands cut to a length of 30 cm are bundled in parallel (hereinafter referred to as sample bundle A), and both ends of a commercially available carbon fiber strand (Vesfite manufactured by Toho Tenax Co., Ltd., 12000 filament, tensile strength 3900 MPa, tensile elastic modulus) (235 GPa).
[0060]
Among these, one bundle of commercially available carbon fiber strands (hereinafter referred to as an induction yarn) used for fixing one end is prepared in advance with a resin bath (inlet guide roller → zigzag liquid immersion roller → outlet guide roller), squeezing guide And what passed through a cylindrical mold (contents cross section: 12.7 mm x 3.5 mm, length 300 mm) was used. The resin bath was kept at 240 ° C. using a flexible ribbon heater.
[0061]
The sample bundle A is placed in front of the resin bath entrance guide roller in parallel with the length direction of the resin bath, and at a speed of 20 m / h, the guide yarn is pulled until the sample bundle A fits in the mold. Removed.
[0062]
The number of carbon fiber strands forming the sample bundle A was determined by the cross-sectional area of the carbon fiber filament and the number of filaments of the carbon fiber strand (adjusted so that the carbon fiber volume content Vf became 60%).
[0063]
The mold filled with the sample bundle A was left at room temperature (24 ° C.) for 24 hours to cure the matrix resin to form a composite (molded product A), and then the molded product A was released. A test piece according to ASTM D 3846-79 was prepared from the molded product A that had been released, and an in-plane shear test (n = 2) was measured according to the same regulation.
[0064]
Example 1
Using a 60% by mass aqueous solution of zinc chloride as a solvent, a solution having 97% by mass of acrylonitrile, 3% by mass of methyl acrylate, a molecular weight of 78,000, and a polymer concentration of 8% by mass as a spinning solution, using a nozzle having 12,000 holes. The mixture was discharged into a 25% by mass aqueous zinc chloride solution at 10 ° C. for coagulation.
[0065]
While washing the coagulated yarn in hot water at 15 to 95 ° C, a total of 3.2 times multi-stage drawing was performed to obtain a water-swollen acrylic fiber strand having a water content of 170% by mass. Next, an aminosilicone-based oil was adjusted to a bath concentration of 20 g / L on the water-swelled fiber, and was applied by a dipping method.
[0066]
Subsequently, it was dried and densified by a suction drum dryer at 70 to 150 ° C. until the water content became 1% by mass or less. Next, after passing through a hot water bath at 80 ° C., restretching was performed 4.5 times in saturated steam of 0.07 MPa, and the solution was transferred into a can to obtain 0.9 denier and 24,000 precursor strands.
[0067]
Using this precursor strand, a flame stabilization treatment was continuously performed for 40 minutes in a hot air circulation type flame stabilization furnace having a temperature gradient within a range of 240 to 270 ° C. by a conventional method. Next, it was treated in a nitrogen gas stream in a carbonization furnace having a temperature gradient of 300 to 1300 ° C. for 5 minutes to obtain carbon fiber strands. The obtained carbon fiber strand had a yield of 1.63 g / m and a specific gravity of 1.80.
[0068]
The carbon fiber strand was treated with an electric quantity of 20 coulomb / g using ammonium sulfate having a concentration of 10 g / L as an electrolyte. The carbon fiber strand subjected to the electrolytic treatment was subsequently washed with water and dried in 150 ° C. heated air. Ion-exchanged water having an electric conductivity of 0.9 μS / cm was used as the diluting water and the washing water for the electrolyte.
[0069]
Subsequently, epoxy-modified urethane (HYDRAN N320, manufactured by Dainippon Ink and Chemicals, Inc.), polyoxyethylene (15) lauryl glycidyl ether (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), octyl stearate (engelbu OS, manufactured by Nippon Rika Co., Ltd.) The emulsion was blended as shown in Table 1 to prepare a sizing solution having a concentration of 30 g / L and a viscosity at 50 ° C. of 48 Pa · s.
[0070]
Ion-exchanged water having an electric conductivity of 0.9 μS / cm was used as dilution water at the time of preparing the sizing solution. Using this sizing solution, a sizing agent was applied to the carbon fiber strand by a dipping method, and dried at 150 ° C. for 60 seconds. The amount of the sizing agent attached to the carbon fiber strand was 1.1% by mass.
[0071]
For the carbon fiber strand thus obtained, the surface calcium concentration fraction (Ca 2s / C 1s ), the surface sulfur concentration fraction (S 2p / C 1s ), and the surface oxygen concentration by X-ray photoelectron spectroscopy (ESCA) Various physical property values such as fraction (O 1s / C 1s ), CV value of Raman spectrum intensity at 1580 to 1600 cm −1 , strand intensity, ILSS, and in-plane shear strength were measured. Table 1 shows the measurement results.
[0072]
Comparative Example 1
A carbon fiber strand was prepared in the same manner as in Example 1 except that the treated water was changed to the conductivity shown in Table 1, and various physical property values of the carbon fiber strand were measured. Table 1 shows the measurement results.
[0073]
Examples 2 and 3, and Comparative Example 2
Bisphenol A type epoxy resin (Epicoat 828, 1002 manufactured by Japan Epoxy Resin Co., Ltd.) was blended as a sizing agent as shown in Table 1, and 100 parts by mass of this sizing agent mixture was emulsified with 20 parts by mass of PO / EO polyether. In the same manner as in Example 1 except that a water emulsion having a viscosity at 50 ° C. shown in Table 1 was used as a sizing solution and the treated water was changed to one having the conductivity shown in Table 1, a carbon fiber strand was prepared. Various physical property values of this carbon fiber strand were measured. Table 1 shows the measurement results.
[0074]
Comparative Example 3
A carbon fiber strand was prepared in the same manner as in Example 3 except that the treatment was performed with an electric quantity of 40 coulomb / g using ammonium sulfate having a concentration of 10 g / L as an electrolytic solution, and the treated water was changed to the conductivity shown in Table 1. The carbon fiber strand was manufactured and various physical property values were measured. Table 1 shows the measurement results.
[0075]
[Table 1]
As shown in the results of Table 1, in Examples 1 to 3, satisfactory results were obtained. However, in Comparative Examples 1 and 2, satisfactory results were not obtained in performance such as in-plane shear strength with ILSS or thermoplastic matrix resin. In Comparative Example 3, satisfactory results were not obtained in performance such as strand strength, ILSS and in-plane shear strength.
[0077]
【The invention's effect】
The carbon fiber strands of the present invention and the carbon fiber strands obtained by the production method of the present invention have excellent physical properties due to, for example, an effect that a sizing agent is uniformly applied and the impregnation of a matrix resin thereon is also uniform. It is possible to obtain a fiber-reinforced composite material.
Claims (5)
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
で示すＣＶ値で４０％以下である請求項１に記載の炭素繊維ストランド。The sizing agent is provided on the surface of the carbon fiber, and the variation of the Raman spectrum intensity at 1580 to 1600 cm −1 of the carbon fiber is represented by the following formula: CV value (%) = (standard deviation of the Raman spectrum intensity) / (the Raman spectrum intensity) Average) x 100
The carbon fiber strand according to claim 1, which has a CV value of 40% or less.
ＣＶ値（％）＝（ラマン分光スペクトル強度の標準偏差）／（ラマン分光スペクトル強度の平均値）×１００
で示すＣＶ値で４０％以下である炭素繊維ストランドの製造方法。A method for producing a carbon fiber strand in which a carbon fiber surface is subjected to a surface treatment such as a surface oxidation treatment, a water washing treatment, and a sizing agent imparting treatment, wherein the surface treatment is performed by X-ray photoelectron spectroscopy (ESCA). The measured calcium concentration fraction (Ca 2s / C 1s ) is 0.6% or less, the sulfur concentration fraction (S 2p / C 1s ) is 0.6% or less, and the oxygen concentration fraction (O 1s / C 1s ). Is 5 to 30%, and the variation of Raman spectrum intensity at 1580 to 1600 cm -1 of the carbon fiber after the surface treatment is represented by the following formula: CV value (%) = (standard deviation of Raman spectrum intensity) / (Raman spectrum spectrum) Average value of strength) x 100
A method for producing a carbon fiber strand having a CV value of 40% or less.
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| JP2012149170A (en) * | 2011-01-19 | 2012-08-09 | Teijin Ltd | Carbon fiber-reinforced polyolefin-based resin composite material and method for producing the same |
| WO2013124760A1 (en) * | 2012-02-20 | 2013-08-29 | Automobili Lamborghini S.P.A. | Process for manufacturing carbon fiber fabrics and fabric manufactured with this process |
| JP2017533355A (en) * | 2014-11-04 | 2017-11-09 | ハネウェル・インターナショナル・インコーポレーテッドＨｏｎｅｙｗｅｌｌ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｉｎｃ． | Novel UHMWPE fiber and manufacturing method |
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2002
- 2002-10-31 JP JP2002319067A patent/JP2004149980A/en active Pending
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| JP2012149170A (en) * | 2011-01-19 | 2012-08-09 | Teijin Ltd | Carbon fiber-reinforced polyolefin-based resin composite material and method for producing the same |
| WO2013124760A1 (en) * | 2012-02-20 | 2013-08-29 | Automobili Lamborghini S.P.A. | Process for manufacturing carbon fiber fabrics and fabric manufactured with this process |
| JP2015510558A (en) * | 2012-02-20 | 2015-04-09 | オートモビリ ランボルギーニ ソチエタ ペル アツイオニ | Method for producing carbon fiber fabric and fabric produced by this method |
| US9511564B2 (en) | 2012-02-20 | 2016-12-06 | Automobili Lamborghini S.P.A. | Process for manufacturing carbon fiber fabrics and fabric manufactured with this process |
| RU2614679C2 (en) * | 2012-02-20 | 2017-03-28 | Аутомобили Ламборгини С.П.А. | Method for carbon fiber fabric production and fabrics obtained by this method |
| US10392745B2 (en) | 2012-02-20 | 2019-08-27 | Automobili Lamborghini S.P.A. | Process for manufacturing carbon fiber fabrics and fabric manufactured with this process |
| JP2017533355A (en) * | 2014-11-04 | 2017-11-09 | ハネウェル・インターナショナル・インコーポレーテッドＨｏｎｅｙｗｅｌｌ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｉｎｃ． | Novel UHMWPE fiber and manufacturing method |
| US11066765B2 (en) | 2014-11-04 | 2021-07-20 | Honeywell International Inc. | UHMWPE fiber and method to produce |
| US11982624B2 (en) | 2020-10-26 | 2024-05-14 | Battelle Savannah River Alliance, Llc | Carbon fiber classification using raman spectroscopy |
| CN115341308A (en) * | 2022-09-01 | 2022-11-15 | 安徽大学 | Continuous production method for preparing polyacrylonitrile spinning solution by X-ray irradiation |
| CN115341308B (en) * | 2022-09-01 | 2023-07-28 | 安徽大学 | Continuous production method for preparing polyacrylonitrile spinning solution by X-ray irradiation |
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