JPS61231266A - Electrolytic surface treatment of carbon fiber - Google Patents

Abstract

(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は炭素繊維の電解表面処理法に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a method for electrolytic surface treatment of carbon fibers.

〔従来技術〕[Prior art]

炭素繊維を用いた複合材料は、軽量、高強力、高弾性等
の卓越した特性をもつため、航空宇宙用構造材、自動車
・産業機械部品、スポーツ用品等に広く使用されている
。Composite materials using carbon fibers have outstanding properties such as light weight, high strength, and high elasticity, so they are widely used in aerospace structural materials, automobile and industrial machine parts, sporting goods, etc.

しかしながら、炭素繊維をこれらの複合材用途に使用す
る場合、炭素繊維自身の強度の重要性もさることながら
、加えて、樹脂などのマトリクスとの接着性を向上させ
、複合材料としての強度、眉間剪断強度の向上をはかる
ことが実用上、極めて重要である。However, when carbon fiber is used for these composite materials, the strength of the carbon fiber itself is important, and in addition, it is important to improve its adhesion to a matrix such as a resin, and to improve the strength of the composite material. In practical terms, it is extremely important to improve shear strength.

こうしたマトリクスとの接着性を向上させるため、炭素
繊維には通常、表面処理が施されるが、その方法として
、炭素繊維の表面を気相酸化、液相酸化、電解酸化等に
より表面処理する方法が知られている。In order to improve the adhesion with such a matrix, carbon fibers are usually surface-treated, and methods include surface-treating the surface of carbon fibers by vapor-phase oxidation, liquid-phase oxidation, electrolytic oxidation, etc. It has been known.

その中でも、特に、炭素繊維を陽極として、電解質水溶
液中で電解酸化処理する方法が、作業性、品質の点から
工業的には有用視されている。Among these, a method in which electrolytic oxidation treatment is performed in an electrolyte aqueous solution using carbon fiber as an anode is considered to be particularly useful industrially from the viewpoint of workability and quality.

炭素繊維の表面電解処理においては、繊維の表面積あた
りの電流密度が高すぎると炭素繊維の強度が低下する。In surface electrolytic treatment of carbon fibers, if the current density per surface area of the fibers is too high, the strength of the carbon fibers will decrease.

他方、低すぎた場合には表面処理効果が不充分となり、
樹脂マトリクスとの接着性は向上されない。従って電解
浴内の電流密度分布を均一にすることが、製品特性の向
上、均一化の上で・極めて重要である。On the other hand, if it is too low, the surface treatment effect will be insufficient,
Adhesion to the resin matrix is not improved. Therefore, it is extremely important to make the current density distribution in the electrolytic bath uniform in order to improve and make the product characteristics uniform.

一方、炭素繊維を陽極として電解を行なう場合、炭素繊
維の抵抗が、電解液の抵抗に比して大きいために、特に
陽極電流入力端子近傍で電流が流れやすく、陽極電流入
力端子から離れるにつれて電流密度が低下し、結果的に
電流密度分布は不均一となりやすい。On the other hand, when performing electrolysis using carbon fiber as an anode, the resistance of the carbon fiber is greater than the resistance of the electrolytic solution, so current tends to flow particularly near the anode current input terminal, and the further away from the anode current input terminal the current flows. The density decreases, and as a result, the current density distribution tends to become non-uniform.

さらに、本発明者らの検討によれば、炭素繊維を連続的
に走行させて電解処理を行う場合は、特に、炭素繊維が
電解液に浸漬しはじめる電解浴入口側付近での電流密度
が高く、不均一性が助長されやすいことが判った。Furthermore, according to studies conducted by the present inventors, when carrying out electrolytic treatment by running carbon fibers continuously, the current density is particularly high near the entrance of the electrolytic bath where the carbon fibers begin to be immersed in the electrolytic solution. , it was found that non-uniformity is likely to be promoted.

例えば、第１図に示す従来公知の電解処理装置で炭素繊
維を電解処理すると、炭素繊維走行方向の電流密度分布
は第４図−ａのようになり、両端部、特に電解浴入口側
の電流密度が高い。For example, when carbon fibers are electrolytically treated using the conventionally known electrolytic treatment apparatus shown in Fig. 1, the current density distribution in the running direction of the carbon fibers becomes as shown in Fig. 4-a, and the current density at both ends, especially at the entrance of the electrolytic bath, is High density.

電流密度分布の均一化をはかる方法として、例えば、特
公昭５Ｂ−５２８８号公報には、炭素繊維と陰極の相対
的間隔を陽極電流入力端子からのの方法により電解処理
したときの電流密度分布は第４図−ｂのようになり、陰
極に面した部分の電流密度はある程度均一化されるが、
第４図−すに示す如く、電解浴入口部での高電流密度は
いぜん解消されない。また、この方法においては、陰極
形状を特殊なものにしたり、或いは電解浴内に糸道を設
置したりする必要があり、操作性、保守性の上で難点が
あり、場合によっては毛羽、糸切れの原因となったりす
る。As a method for making the current density distribution uniform, for example, Japanese Patent Publication No. 5B-5288 discloses that the current density distribution when the relative spacing between the carbon fiber and the cathode is electrolytically treated from the anode current input terminal is As shown in Figure 4-b, the current density in the part facing the cathode is made uniform to some extent, but
As shown in FIG. 4, the high current density at the inlet of the electrolytic bath is not eliminated at all. In addition, this method requires a special cathode shape or a thread path installed in the electrolytic bath, which poses difficulties in terms of operability and maintainability, and in some cases, fuzz and threads may form. It may cause breakage.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明者らは、炭素繊維の電解表面処理時の電流密度の
均一化、特に電解浴入口部における電流密度の均一化を
はかり、特性及び均一性のすぐれた炭素繊維を得る方法
について鋭意検討し、本発明を見い出すに到った。The inventors of the present invention have conducted intensive studies on a method to obtain carbon fibers with excellent properties and uniformity by uniformizing the current density during electrolytic surface treatment of carbon fibers, particularly at the entrance of the electrolytic bath. The inventors have now discovered the present invention.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、連続的に走行する炭素繊維を陽極として、電
解質水溶液中で電解表面処理する方法において、電解浴
を出た直後に設けた陽極電流入力端子から炭素繊維に電
流を供給するとが〆、電解浴に入る直前の炭素繊維の電
位を陰極電位に等しくすることを特徴とする炭素繊維の
電解表面処理法である。The present invention provides a method for electrolytically surface treating a continuously running carbon fiber in an aqueous electrolyte solution using the anode as an anode, in which a current is supplied to the carbon fiber from an anode current input terminal provided immediately after exiting the electrolytic bath. This is an electrolytic surface treatment method for carbon fibers, which is characterized in that the potential of the carbon fibers immediately before entering the electrolytic bath is made equal to the cathode potential.

本発明において、電流は電解浴を出た直後に設けた陽極
電流入力端子より炭素繊維に供給される。In the present invention, current is supplied to the carbon fiber from an anode current input terminal provided immediately after exiting the electrolytic bath.

かかる陽極電流入力端子としては、例えばカーボンロー
ル等の導電性ロール、あるいは非接触型陽極電流入力端
子等公知のものが用いられる。As such an anode current input terminal, a known one such as a conductive roll such as a carbon roll or a non-contact type anode current input terminal is used.

供給する電流、電圧は、炭素繊維の種類、本数、処理速
度、電解質の種類等に応じて適宜選定される。通常、電
流は炭素繊維束１本あたり約１０ｍＡから５Ａ、電圧は
約５００ｍＶからＩＯＶ程度である。The current and voltage to be supplied are appropriately selected depending on the type and number of carbon fibers, processing speed, type of electrolyte, etc. Usually, the current is about 10 mA to 5 A per carbon fiber bundle, and the voltage is about 500 mV to IOV.

使用する電解質は電解に際し、陽極に本質的に酸素を生
成するものであればよ（、例えば、硫酸、硝酸、リン酸
等の酸、硫酸アンモニウム、硝酸アンモニウム、炭酸ア
ンモニウム等の基環公知のものが用いられる。また、電
解質の濃度、電解液の温度は電解質の種類及びその他の
装置条件によるが、通常、濃度は０．１ないし１０％程
度、温度は室温ないし８０℃程度で行われる。The electrolyte to be used may be one that essentially generates oxygen at the anode during electrolysis (for example, acids such as sulfuric acid, nitric acid, phosphoric acid, and known base ring materials such as ammonium sulfate, ammonium nitrate, ammonium carbonate, etc.) may be used. Although the concentration of the electrolyte and the temperature of the electrolytic solution depend on the type of electrolyte and other equipment conditions, the concentration is usually about 0.1 to 10%, and the temperature is about room temperature to 80°C.

陰極としては電解質溶液に対し耐腐食性の導電材料、例
えば、グラファイト、ニッケル、ステンレススチール等
公知のものが用いられ、形状、寸法等は装置に大きさ、
操作性、保守性等を考慮して適宜法められる。As the cathode, a conductive material that is resistant to corrosion by the electrolyte solution, such as graphite, nickel, stainless steel, etc., is used, and its shape and dimensions depend on the size and size of the device.
Laws are established as appropriate, taking into consideration operability, maintainability, etc.

本発明においては、電解浴に入る直前の炭素繊維の電位
を実質的に陰極電位に等しくすることが重要であり、こ
れによりはじめて電解浴入口部での高電流密度が解消さ
れる。このための手段としては、例えば、電解浴に入る
直前に陽極電流入力端子と同様の導電性ロール、非接触
型零播播鰺≠端子等を設け、それらの端子と陰極を導線
で接続することが簡単でよい。In the present invention, it is important to make the potential of the carbon fibers immediately before entering the electrolytic bath substantially equal to the cathode potential, and only then can the high current density at the entrance of the electrolytic bath be eliminated. As a means for this, for example, immediately before entering the electrolytic bath, a conductive roll similar to the anode current input terminal, a non-contact type zero dissemination terminal, etc. is provided, and these terminals and the cathode are connected with a conductive wire. is easy and good.

第３図は本発明の方法を実施するのに使用する装置の一
例である。同図において、炭素繊維１は電解浴２に入る
直前に設けた端子３を介して電解液中の陰極４と電気的
に接続されている。一方、直流電源５より、電解浴を出
た直後に設けた陽極電流入力端子６を介して炭素繊維１
に電流が供給され、電解浴内において炭素繊維を陽極と
して電解がおこなわれる。FIG. 3 is an example of an apparatus used to carry out the method of the invention. In the figure, a carbon fiber 1 is electrically connected to a cathode 4 in an electrolytic solution via a terminal 3 provided immediately before entering an electrolytic bath 2. On the other hand, the carbon fiber 1 is connected from the DC power source 5 to the anode current input terminal 6 provided immediately after exiting the electrolytic bath.
An electric current is supplied to the electrolytic bath, and electrolysis is performed using the carbon fiber as an anode in the electrolytic bath.

なお、本発明において電流密度とは、陽極であ内の炭素
繊維の近傍の任意の距離βｃｍ離れた２点における電解
液の電位の差ΔＥ　（Ｖ）を測定し、電解液の比抵抗ρ
（Ω・ｃｍ）とから次式を用いて算出することができる
。In the present invention, the current density refers to the difference in potential ΔE (V) of the electrolytic solution at two points near the inner carbon fiber at an arbitrary distance β cm apart, and the specific resistance ρ of the electrolytic solution
(Ω·cm) using the following formula.

ｉ＝ΔＥ／ρｘｌ（Ａ／ａｎり ｉ：電流密度 〔発明の効果〕 本発明の方法によれば、何ら特殊で複雑な装置を必要と
せず電解浴内、特に電解浴入口部における電流密度分布
を均一化することができ、斑のない、均一な表面処理が
可能となる。また、人口部の未処理繊維に急激に過大な
電流が流れることがなくなるので、得られる炭素・繊維
の強度、接着性ともすぐれたものとなる。さらに従来法
のように何ら特殊な装置、糸道を必要とせず、簡単に実
施できるので、工業的にも極めて有利である。i=ΔE/ρxl (A/anri: current density [Effects of the invention]) According to the method of the present invention, the current density distribution within the electrolytic bath, especially at the entrance of the electrolytic bath, can be improved without the need for any special or complicated equipment. This makes it possible to achieve a uniform surface treatment with no spots.Also, since excessive current will not suddenly flow through the untreated fibers in the artificial part, the strength of the resulting carbon fibers and It also has excellent adhesive properties.Furthermore, unlike conventional methods, it does not require any special equipment or thread guide and can be easily carried out, making it extremely advantageous from an industrial perspective.

〔実施例〕〔Example〕

以下に実施例を挙げて本発明を具体的に説明する。 The present invention will be specifically described below with reference to Examples.

実施例１ 単糸繊度１．３ｄデニール、Ｉ　２０００フイラメント
のアクリル系長繊維を最終的に１３００℃の窒素雰囲気
中で焼成して得た炭素繊維を第３図に示す電解装置を用
いて電解表面処理した。電解質として１％硝酸を用い、
電流５００ｍＡ、電圧５．５Ｖ、処理時間２０秒で連続
的に処理を行なった。Example 1 Carbon fibers obtained by finally firing acrylic long fibers with a single filament fineness of 1.3 d denier and I 2000 filament in a nitrogen atmosphere at 1300°C were subjected to electrolytic surface treatment using the electrolytic apparatus shown in Fig. 3. Processed. Using 1% nitric acid as the electrolyte,
Processing was performed continuously at a current of 500 mA, a voltage of 5.5 V, and a processing time of 20 seconds.

電解浴内の電流密度分布は第４図−Ｃに示すごとくであ
り、電解浴入口部における不均一は見られなかった。The current density distribution in the electrolytic bath was as shown in FIG. 4-C, and no non-uniformity was observed at the entrance of the electrolytic bath.

電解処理した繊維を引き続き水洗、サイジング付与、乾
燥した後巻取った。The electrolytically treated fibers were subsequently washed with water, sized, dried, and then wound up.

未処理繊維および処理繊維について、ＪＩＳ−Ｒ７６０
１に準じ、同解説例２の樹脂を用いてストランド強度を
測定したところ、それぞれ４０６ｋｇ／ｍｍ”及び４１
０　ｋｇ／ｍｍ”であった。JIS-R760 for untreated fibers and treated fibers
According to Example 1, the strand strength was measured using the resin of Explanation Example 2, and the results were 406 kg/mm" and 41 kg/mm, respectively.
0 kg/mm”.

さらに、樹脂との接着性を見るために、エポキシ樹脂（
チバガイギー社、ＭＹ７２０．１００部、ジアミノジフ
ェニルスルホン３０部、三弗化ホウ素モノエチルアミン
１．５部）のメチルエチルケトン溶液を含浸したプリプ
レグを１３０℃Ｘ６０分、ついで１８０℃×１２０分、
加熱硬化し、平板試験片を作成し、三点曲げショートビ
ーム法（Ｌ／Ｄ＝４）で眉間剪断強度（以下、「ｒＬｓ
ｓＪという）を測定した。未処理系及び処理系のＩ　Ｌ
ＳＳの値はそれぞれ、８．３　ｋｇ　／　ｍｍ　”及び
１３．１　ｋｇ／ｍｍ”であった。Furthermore, in order to check the adhesion with the resin, epoxy resin (
A prepreg impregnated with a methyl ethyl ketone solution (Ciba Geigy, MY720.100 parts, 30 parts of diaminodiphenylsulfone, 1.5 parts of boron trifluoride monoethylamine) was heated at 130°C for 60 minutes, then at 180°C for 120 minutes.
After heating and curing, a flat test piece was prepared, and the glabellar shear strength (hereinafter referred to as "rLs
sJ) was measured. I L of untreated system and treated system
The SS values were 8.3 kg/mm'' and 13.1 kg/mm'', respectively.

実施例２ 実施例１で用いた炭素繊維を、実施例１と同様な装置を
用い、同様な条件で、処理本数を８本にして同時に電解
表面処理をおこなった。得られた繊維は、引続いて、水
洗、サイジング、乾燥して巻取り、物性測定に供した。Example 2 The carbon fibers used in Example 1 were subjected to electrolytic surface treatment at the same time using the same apparatus as in Example 1 and under the same conditions, with the number of fibers treated being 8. The obtained fibers were subsequently washed with water, sized, dried, wound up, and subjected to physical property measurements.

８本の繊維について、引張強度及びＩ　ＬＳＳの平均値
及びバラツキは表１の通りであった。Table 1 shows the average values and variations in tensile strength and ILSS for the eight fibers.

一方、８本のうちの１本について、長さ方向に５分割し
て測定した引張強度及びＩ　ＬＳＳの平均値及びバラツ
キを同じく表１に示す。On the other hand, Table 1 also shows the average values and dispersion of the tensile strength and ILSS of one of the eight pieces, which were measured by dividing into five pieces in the length direction.

表１からも明らかなように、本発明の方法で得られた繊
維は特性及び均一性ともに極めて良好である。As is clear from Table 1, the fibers obtained by the method of the present invention have extremely good properties and uniformity.

比較例１ 実施例１で用いた炭素繊維を第３図に示す装置を用いて
、端子３と陰極２の間を接続せずに実施。Comparative Example 1 The carbon fiber used in Example 1 was carried out using the apparatus shown in FIG. 3 without connecting the terminal 3 and the cathode 2.

例１と同一の条件で電解処理した。その時の電流密度分
布は第４図−ｄに示す如きであり、電解浴入口部で高電
流密度を示した。得られた炭素繊維の引張強度は３９４
ｋｇ／ｍｍ２、Ｉ　ＬＳＳは１２．１ｋｇ　／　ｍｍ　
２であった。Electrolytic treatment was carried out under the same conditions as in Example 1. The current density distribution at that time was as shown in Figure 4-d, with a high current density at the entrance of the electrolytic bath. The tensile strength of the obtained carbon fiber was 394
kg/mm2, I LSS is 12.1kg/mm
It was 2.

比較例２ 第１図に示す従来法装置で、電解浴の前後両側より通電
して、実施例２と同様の条件で電解処理を行なった。得
られた８本の繊維の特性及びそのうちの１本について長
さ方向に５分割して測定した特性の平均値及びバラツキ
を表１に示す。Comparative Example 2 Electrolytic treatment was carried out using the conventional apparatus shown in FIG. 1 under the same conditions as in Example 2, by applying electricity from both the front and back sides of the electrolytic bath. Table 1 shows the characteristics of the eight fibers obtained and the average value and variation of the characteristics measured by dividing one of the fibers into five in the length direction.

この時の電流密度分布は第４図−ａに示す如くであった
。The current density distribution at this time was as shown in FIG. 4-a.

以下余白 表　　１ 比較例３ 第２図に示す装置を用い、実施例１と同様の条件で電解
処理を行った。電流密度分布は第４図−すの如くであり
、電解浴入口部で高電流密度を示した。Table 1 Comparative Example 3 Electrolytic treatment was carried out under the same conditions as in Example 1 using the apparatus shown in FIG. The current density distribution was as shown in Figure 4, with a high current density at the inlet of the electrolytic bath.

【図面の簡単な説明】[Brief explanation of drawings]

第１図および第２図は従来法の炭素繊維電解酸化表面処
理に用いる装置の断面図であり、第３図は本発明の炭素
繊維電解酸化表面処理に用いる装置の一例を示す断面図
である。第４図は、第１図〜第３図に示す装置を用いて
炭素繊維電解酸化表面処理を行った時の電解浴内電流密
度分布を示す曲線である。 １：炭素繊維、２：電解浴、３：通電端子、４：陰極、
５：直流電源、６：陽極電流入力端子。 第２図において、縦軸および横軸はそれぞれ、電解浴内
の電流密度および位置の相対値である。 第１図 り 第２図 第３図FIGS. 1 and 2 are cross-sectional views of an apparatus used for conventional carbon fiber electrolytic oxidation surface treatment, and FIG. 3 is a cross-sectional view showing an example of the apparatus used for carbon fiber electrolytic oxidation surface treatment of the present invention. . FIG. 4 is a curve showing the current density distribution in the electrolytic bath when carbon fiber electrolytically oxidized surface treatment is performed using the apparatus shown in FIGS. 1 to 3. 1: Carbon fiber, 2: Electrolytic bath, 3: Current-carrying terminal, 4: Cathode,
5: DC power supply, 6: Anode current input terminal. In FIG. 2, the vertical and horizontal axes are the relative values of current density and position within the electrolytic bath, respectively. Figure 1 Figure 2 Figure 3

Claims (1)

【特許請求の範囲】[Claims] 連続的に走行する炭素繊維を陽極として、電解質水溶液
中で電解表面処理する方法において、電解浴を出た直後
に設けた陽極電流入力端子から炭素繊維に電流を供給す
るとともに、電解浴に入る直前の炭素繊維の電位を陰極
電位に等しくすることを特徴とする炭素繊維の電解表面
処理方法。In a method of electrolytic surface treatment in an electrolyte aqueous solution using a continuously running carbon fiber as an anode, a current is supplied to the carbon fiber from an anode current input terminal provided immediately after exiting the electrolytic bath, and a current is supplied to the carbon fiber immediately before entering the electrolytic bath. A method for electrolytic surface treatment of carbon fibers, characterized in that the potential of the carbon fibers is made equal to the cathode potential.