JP5489831B2 - Carbon fiber sheet, heat-treated flame-resistant fiber sheet, and method for producing them - Google Patents

Carbon fiber sheet, heat-treated flame-resistant fiber sheet, and method for producing them Download PDF

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JP5489831B2
JP5489831B2 JP2010093548A JP2010093548A JP5489831B2 JP 5489831 B2 JP5489831 B2 JP 5489831B2 JP 2010093548 A JP2010093548 A JP 2010093548A JP 2010093548 A JP2010093548 A JP 2010093548A JP 5489831 B2 JP5489831 B2 JP 5489831B2
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一真 黒川
哲也 赤松
祐介 高見
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Toho Rayon Co Ltd
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本発明は、炭素繊維シート、熱処理が施された耐炎繊維のシート状加工物(以下、「熱処理耐炎繊維シート」ともいう)及びそれらの製造方法に関する。更に詳しくは、表面平滑性が優れ、シートの厚さの均一性が高い炭素繊維シート、及び焼成することにより前記炭素繊維シートになる熱処理耐炎繊維シート及びそれらの製造方法に関する。   The present invention relates to a carbon fiber sheet, a heat-treated flame-resistant fiber sheet-like processed product (hereinafter also referred to as “heat-treated flame-resistant fiber sheet”), and a method for producing them. More specifically, the present invention relates to a carbon fiber sheet having excellent surface smoothness and high sheet thickness uniformity, a heat-treated flame resistant fiber sheet that becomes the carbon fiber sheet by firing, and a method for producing the same.

炭素繊維クロスや炭素繊維フェルト、炭素繊維ペーパー等の炭素繊維シートは、軽量であって、機械的特性及び導電性に優れるため、燃料電池の電極材や、樹脂と複合化する補強繊維シート等として、広く工業的に利用されている。   Carbon fiber sheets such as carbon fiber cloth, carbon fiber felt, and carbon fiber paper are lightweight and have excellent mechanical properties and electrical conductivity. Therefore, they are used as fuel cell electrode materials and reinforcing fiber sheets that are combined with resin. Widely used industrially.

炭素繊維シートは、フィラメント糸やステーブル糸等の炭素繊維を、製織や抄紙等によりシート加工して製造される。この製造方法においては、剛性の高い炭素繊維をシート加工するので、シート加工は困難を伴う。そのため、厚さの薄い炭素繊維のシート状物を作製することは困難である。   The carbon fiber sheet is manufactured by processing a carbon fiber such as a filament yarn or a stable yarn by weaving or paper making. In this manufacturing method, since a highly rigid carbon fiber is processed into a sheet, the sheet processing is difficult. Therefore, it is difficult to produce a thin carbon fiber sheet.

この問題を解消するために、炭素繊維の前駆体繊維である耐炎繊維を予めシート加工しておき、このシートを焼成して炭素繊維シートを製造する方法が提案されている。耐炎繊維は剛性が低いため、シート加工が容易である。   In order to solve this problem, a method has been proposed in which a flame resistant fiber, which is a carbon fiber precursor fiber, is processed into a sheet in advance, and the sheet is fired to produce a carbon fiber sheet. Since the flame resistant fiber has low rigidity, sheet processing is easy.

特許文献1には、炭素繊維の前駆体繊維である耐炎繊維をバインダー材料と一緒に抄紙して耐炎繊維シートを作製した後、プレス圧をかけながら焼成することにより、厚さの薄い炭素繊維シートを製造する方法が開示されている。しかし、この製造方法は、焼成時に耐炎繊維が収縮するため、得られる炭素繊維シートにシワやウネリが発生する。そのため、表面平滑性が高い炭素繊維シートが得られない。   In Patent Document 1, a flame resistant fiber sheet, which is a carbon fiber precursor fiber, is made together with a binder material to prepare a flame resistant fiber sheet, and then fired while applying a press pressure, whereby a thin carbon fiber sheet is obtained. A method of manufacturing is disclosed. However, in this production method, since the flame-resistant fiber contracts during firing, wrinkles and undulation are generated in the obtained carbon fiber sheet. Therefore, a carbon fiber sheet with high surface smoothness cannot be obtained.

特許文献2には、炭素繊維の前駆体繊維である耐炎繊維を製織して耐炎繊維シートを作製した後、この耐炎繊維シートを焼成して炭素繊維シートを製造する方法が開示されている。しかし、この炭素繊維シートは、焼成時に耐炎繊維が収縮するため、シート面中央部の厚さがシート面外縁部の厚さよりも厚くなる。従って、この方法の場合も厚さの均一性が高い炭素繊維シートは得られない。   Patent Document 2 discloses a method for producing a carbon fiber sheet by weaving a flame resistant fiber sheet, which is a carbon fiber precursor fiber, and then firing the flame resistant fiber sheet. However, in this carbon fiber sheet, since the flame-resistant fiber contracts during firing, the thickness of the central portion of the sheet surface is greater than the thickness of the outer edge portion of the sheet surface. Therefore, even in this method, a carbon fiber sheet having high thickness uniformity cannot be obtained.

以上のように、従来表面平滑性及び厚さの均一性が高く、かつ厚さが500μm以下の薄い炭素繊維シートは得られていない。   As described above, a thin carbon fiber sheet having high surface smoothness and thickness uniformity and a thickness of 500 μm or less has not been obtained.

特開2004−27435号公報JP 2004-27435 A 特開2003−268651号公報JP 2003-268651 A

本発明の課題は、上記従来技術の問題点を解決し、表面平滑性及び厚さの均一性が高く、かつ厚さが500μm以下の薄い炭素繊維シート及びその製造方法を提供することである。   An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a thin carbon fiber sheet having a high surface smoothness and a uniform thickness and having a thickness of 500 μm or less, and a method for producing the same.

本発明者らは、炭素繊維の前駆体繊維である耐炎繊維を所定の条件で予め熱処理しておくことにより、耐炎繊維の熱収縮率(後述)が低下することを見出した(以下、熱処理が施された耐炎繊維を「熱処理耐炎繊維」ともいう)。また、繊維比重が所定範囲になるように熱処理を行うことにより、熱処理耐炎繊維が柔軟性を維持し、シート加工が容易に行えることを見出した。そして、この熱処理耐炎繊維をシート加工して焼成すると、シート厚さが薄くても表面平滑性及び厚さの均一性が高い炭素繊維シートが得られることを見出し、本発明を完成するに至った。   The inventors of the present invention have found that the heat shrinkage rate (described later) of the flame resistant fiber is decreased by preliminarily heat-treating the flame resistant fiber, which is a carbon fiber precursor fiber, under predetermined conditions (hereinafter referred to as heat treatment). The applied flame resistant fiber is also referred to as “heat treated flame resistant fiber”). Further, it has been found that by performing heat treatment so that the fiber specific gravity falls within a predetermined range, the heat treated flame resistant fiber maintains flexibility and sheet processing can be easily performed. And when this heat-treated flame resistant fiber was processed and fired, it was found that even if the sheet thickness was thin, a carbon fiber sheet having high surface smoothness and high uniformity of thickness was obtained, and the present invention was completed. .

上記課題を解決する本発明は、以下に記載のものである。   The present invention for solving the above problems is as follows.

〔1〕
厚さ平均値が50〜500μmの炭素繊維シートであって、該炭素繊維シートの厚さの最大値と最小値との差が、該炭素繊維シートの厚さ平均値の10%未満であることを特徴とする炭素繊維シート。
[1]
The carbon fiber sheet has an average thickness of 50 to 500 μm, and the difference between the maximum value and the minimum value of the thickness of the carbon fiber sheet is less than 10% of the average thickness of the carbon fiber sheet. Carbon fiber sheet characterized by

〔2〕
(a)炭素繊維の前駆体繊維である耐炎繊維を不活性雰囲気下、500〜900℃で0.1〜60分間熱処理して、アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜15%の熱処理耐炎繊維を得る工程と、
(b)前記熱処理耐炎繊維をシート加工して熱処理耐炎繊維シートを得る工程と、
(c)前記熱処理耐炎繊維シートを不活性雰囲気下で焼成して炭素繊維シートを得る工程と、
を有する〔1〕に記載の炭素繊維シートの製造方法。
[2]
(A) A flame resistant fiber, which is a precursor fiber of carbon fiber, is heat-treated at 500 to 900 ° C. for 0.1 to 60 minutes in an inert atmosphere, and has a fiber specific gravity of 1.35 to 1.75 and heat. Obtaining a heat treated flame resistant fiber having a shrinkage of 2.0-15%;
(B) a step of processing the heat-treated flame resistant fiber to obtain a heat treated flame resistant fiber sheet;
(C) firing the heat-treated flame resistant fiber sheet in an inert atmosphere to obtain a carbon fiber sheet;
[1] The method for producing a carbon fiber sheet according to [1].

〔3〕
アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜15%である熱処理耐炎繊維から成る、〔1〕に記載の炭素繊維シート製造用の熱処理耐炎繊維シート。
[3]
The heat-treated flame-resistant fiber sheet for producing a carbon fiber sheet according to [1], comprising a heat-treated flame-resistant fiber having a fiber specific gravity by an Archimedes method of 1.35 to 1.75 and a heat shrinkage rate of 2.0 to 15%.

〔4〕
(a)炭素繊維の前駆体繊維である耐炎繊維を不活性雰囲気下、500〜900℃で0.1〜60分間熱処理して、アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜15%の熱処理耐炎繊維を得る工程と、
(b)前記熱処理耐炎繊維をシート加工して熱処理耐炎繊維シートを得る工程と、
を有する〔3〕に記載の熱処理耐炎繊維シートの製造方法。
[4]
(A) A flame resistant fiber, which is a precursor fiber of carbon fiber, is heat-treated at 500 to 900 ° C. for 0.1 to 60 minutes in an inert atmosphere, and has a fiber specific gravity of 1.35 to 1.75 and heat. Obtaining a heat treated flame resistant fiber having a shrinkage of 2.0-15%;
(B) a step of processing the heat-treated flame resistant fiber to obtain a heat treated flame resistant fiber sheet;
[3] The method for producing a heat-resistant flame-resistant fiber sheet according to [3].

本発明の炭素繊維シートは、熱処理耐炎繊維をシート加工した後、焼成して得られる。熱処理耐炎繊維は、繊維比重が所定範囲に調整されているため柔軟であり、厚さの薄いシート状物に簡単に加工できる。また、この熱処理耐炎繊維は熱収縮率が小さいため、焼成後に得られる炭素繊維シートの表面平滑性及び厚さの均一性が高い。   The carbon fiber sheet of the present invention is obtained by baking a heat-treated flame resistant fiber after sheet processing. The heat-treated flame resistant fiber is flexible because the fiber specific gravity is adjusted within a predetermined range, and can be easily processed into a thin sheet. Moreover, since this heat-resistant flame resistant fiber has a small thermal shrinkage rate, the surface smoothness and thickness uniformity of the carbon fiber sheet obtained after firing are high.

(炭素繊維シート)
本発明において、炭素繊維シートとは、炭素繊維クロス、炭素繊維フェルト、炭素繊維ペーパー等のシート状物をいう。
(Carbon fiber sheet)
In the present invention, the carbon fiber sheet refers to a sheet-like material such as carbon fiber cloth, carbon fiber felt, or carbon fiber paper.

本発明の炭素繊維シート(以下、「本炭素繊維シート」と略記する)は、厚さ平均値が50〜500μmであり、100〜400μmが好ましい。厚さ平均値が50μm未満の場合は、炭素繊維シートの強度が低くなり、取扱い性が低下する。厚さ平均値が500μmを超える場合は、シートの面方向に沿う厚さの均一性が悪くなる。厚さ平均値は、目付や、熱圧縮の際の温度や圧力を調整することにより、制御できる。   The carbon fiber sheet of the present invention (hereinafter abbreviated as “the present carbon fiber sheet”) has a thickness average value of 50 to 500 μm, preferably 100 to 400 μm. When the thickness average value is less than 50 μm, the strength of the carbon fiber sheet is lowered, and the handleability is lowered. When the average thickness exceeds 500 μm, the uniformity of the thickness along the surface direction of the sheet is deteriorated. The average thickness value can be controlled by adjusting the basis weight and the temperature and pressure during thermal compression.

本炭素繊維シートの厚さの最大値と最小値との差は、該炭素繊維シートの厚さ平均値の10%未満である。10%以上の場合、炭素繊維シートの厚さの均一性が低く、炭素繊維シートの用途が制限される。   The difference between the maximum value and the minimum value of the thickness of the carbon fiber sheet is less than 10% of the average thickness of the carbon fiber sheet. In the case of 10% or more, the thickness uniformity of the carbon fiber sheet is low, and the use of the carbon fiber sheet is limited.

本発明において、炭素繊維シートの「厚さ」は、直径5mmの円形圧板を用いてシートの厚さ方向に1.2Nの荷重(61.9kPa)を負荷した時のシートの厚さを表す。「厚さ平均値」は、10cm角のシート面を碁盤の目状に9面に区分(即ち、約3.33cm角で9面に区分)し、区分された各面の中心部における厚さを測定し、これら9点の厚さ測定値を平均した値を表す。また、厚さの「最大値」及び「最小値」とは、上記9点の厚さの測定値における最大値及び最小値をいう。   In the present invention, the “thickness” of the carbon fiber sheet represents the thickness of the sheet when a 1.2 N load (61.9 kPa) is applied in the sheet thickness direction using a circular pressure plate having a diameter of 5 mm. "Thickness average value" is a 10 cm square sheet surface divided into 9 faces in a grid pattern (ie, approximately 3.33 cm square and divided into 9 faces), and the thickness at the center of each of the divided faces And the average value of these nine thickness measurements. Further, the “maximum value” and “minimum value” of the thickness mean the maximum value and the minimum value in the measured values of the thickness at the nine points.

本炭素繊維シートの繊維径は5〜20μmが好ましく、6〜13μmがより好ましい。扁平な断面の炭素繊維の場合、長径と短径の平均を繊維径とする。繊維径が5μm未満の場合は、単繊維直径が細すぎて繊維強度が低いため、シート強力が不足する。また、炭素繊維シートから脱落した炭素繊維が人体に悪影響を及ぼす可能性がある。繊維径が20μmを超える場合は、シートを構成する炭素単繊維の外周の形状がシート表面に浮き上がり、シート表面に凹凸が形成される。その結果、表面平滑性が悪化する。また、シート表面に形成される凹凸に起因して炭素繊維シートの接触電気抵抗が大きくなるため、電気抵抗が小さいことが要求される電極材料等の用途には好ましくなくなる。更に、焼成時に繊維強度が低下して炭素繊維微粉末が多量に発生する。   The fiber diameter of the present carbon fiber sheet is preferably 5 to 20 μm, and more preferably 6 to 13 μm. In the case of carbon fibers having a flat cross section, the average of the major axis and the minor axis is defined as the fiber diameter. When the fiber diameter is less than 5 μm, the sheet strength is insufficient because the single fiber diameter is too thin and the fiber strength is low. In addition, the carbon fibers dropped from the carbon fiber sheet may adversely affect the human body. When the fiber diameter exceeds 20 μm, the shape of the outer periphery of the carbon single fiber constituting the sheet rises on the sheet surface, and irregularities are formed on the sheet surface. As a result, the surface smoothness is deteriorated. Moreover, since the contact electrical resistance of the carbon fiber sheet is increased due to the irregularities formed on the sheet surface, it is not preferable for applications such as electrode materials that require a low electrical resistance. Furthermore, the fiber strength is reduced during firing, and a large amount of fine carbon fiber powder is generated.

本炭素繊維シートの目付は30〜200g/mが好ましく、50〜150g/mがより好ましい。目付が30g/m未満の場合は、シート強力が低くなり、取扱い性が低下する。目付が200g/mを超える場合は、所期の厚さの炭素繊維シートを得ることが困難になる。 Basis weight of the carbon fiber sheet is preferably 30~200g / m 2, 50~150g / m 2 is more preferable. When the basis weight is less than 30 g / m 2 , the sheet strength is lowered, and the handleability is lowered. When the basis weight exceeds 200 g / m 2 , it becomes difficult to obtain a carbon fiber sheet having a desired thickness.

本炭素繊維シートの嵩密度は、0.2〜0.7g/cmが好ましい。嵩密度が0.2g/cm未満の場合は、シート強度が低くなり、シートの取扱い性が低下する。嵩密度が0.7g/cmを超える場合は、シートの面方向における厚さの均一性が悪くなる。 The bulk density of the present carbon fiber sheet is preferably 0.2 to 0.7 g / cm 3 . When the bulk density is less than 0.2 g / cm 3 , the sheet strength is lowered, and the handleability of the sheet is lowered. When the bulk density exceeds 0.7 g / cm 3 , the uniformity of thickness in the surface direction of the sheet is deteriorated.

本炭素繊維シートは、その物性が上記範囲内にあれば、製造方法は特に限定されるものではないが、例えば以下の方法で製造できる。   As long as the physical properties of the present carbon fiber sheet are within the above range, the production method is not particularly limited. For example, the carbon fiber sheet can be produced by the following method.

(本炭素繊維シートの製造方法)
本炭素繊維シートは、炭素繊維の前駆体繊維である耐炎繊維を熱処理して得られる熱処理耐炎繊維をシート加工して熱処理耐炎繊維シートを得、この熱処理耐炎繊維シートを焼成することにより製造される。
(Method for producing the carbon fiber sheet)
This carbon fiber sheet is manufactured by sheet-treating a heat-treated flame-resistant fiber obtained by heat-treating a flame-resistant fiber that is a precursor fiber of carbon fiber to obtain a heat-treated flame-resistant fiber sheet, and firing the heat-treated flame-resistant fiber sheet. .

耐炎繊維は、炭素繊維の前駆体繊維を空気中において200〜400℃で2〜5時間加熱することによって製造される。この製造方法は公知の方法である。前駆体繊維を構成する繊維原料は、ポリアクリロニトリル(PAN)系繊維、ピッチ系繊維、レーヨン系繊維等のいずれの繊維であってもよいが、強度、伸度の比較的高いPAN系繊維が好ましい。   Flame resistant fibers are produced by heating carbon fiber precursor fibers in air at 200-400 ° C. for 2-5 hours. This manufacturing method is a known method. The fiber raw material constituting the precursor fiber may be any fiber such as polyacrylonitrile (PAN) fiber, pitch fiber, rayon fiber, etc., but PAN fiber having relatively high strength and elongation is preferred. .

PAN系繊維は、PAN系重合体を公知の湿式又は乾式紡糸によって得ることができる。PAN系重合体としては、アクリロニトリル単量体を単独重合させたもの、及びアクリロニトリル単量体とその他ビニル系単量体とを共重合させたものがある。その他のビニル系単量体としては、アクリル酸、イタコン酸、又はこれらのエステル類、塩類、アクリルアミド等の既知のビニル系単量体が用いられる。その他のビニル系単量体の共重合割合は、12質量%以内が好ましく、8質量%以内が特に好ましい。   The PAN-based fiber can be obtained by a known wet or dry spinning of a PAN-based polymer. Examples of the PAN polymer include those obtained by homopolymerizing an acrylonitrile monomer and those obtained by copolymerizing an acrylonitrile monomer and another vinyl monomer. As other vinyl monomers, known vinyl monomers such as acrylic acid, itaconic acid, esters thereof, salts, acrylamide and the like are used. The copolymerization ratio of other vinyl monomers is preferably within 12% by mass, and particularly preferably within 8% by mass.

上記のようにして得られる耐炎繊維は、不活性ガス中で500〜900℃に加熱することにより熱処理が施される。加熱温度が500℃未満の場合、熱処理耐炎繊維の熱収縮率が十分に低くならない。そのため、この熱処理耐炎繊維を用いて製造する炭素繊維シートは、シート表面にシワやウネリが多く発生し、表面平滑性及び厚さの均一性が悪くなる。加熱温度が900℃を超える場合、熱処理耐炎繊維の剛性が高くなって、シート状に加工することが困難になる。   The flame resistant fiber obtained as described above is subjected to heat treatment by heating to 500 to 900 ° C. in an inert gas. When the heating temperature is less than 500 ° C., the heat shrinkage rate of the heat-treated flame resistant fiber is not sufficiently lowered. For this reason, the carbon fiber sheet produced using this heat-treated flame resistant fiber has many wrinkles and undulations on the surface of the sheet, resulting in poor surface smoothness and thickness uniformity. When heating temperature exceeds 900 degreeC, the rigidity of a heat-resistant flame resistant fiber becomes high and it becomes difficult to process it into a sheet form.

加熱時間は、0.1〜60分間であり、0.2〜30分間が好ましく、1〜10分間がより好ましい。加熱時間が0.1分間未満である場合、熱処理耐炎繊維の熱収縮率が十分に低くならない。加熱時間が60分間を超える場合、熱処理耐炎繊維の剛性が高くなって、シート状に加工することが困難になる。   The heating time is 0.1 to 60 minutes, preferably 0.2 to 30 minutes, and more preferably 1 to 10 minutes. When the heating time is less than 0.1 minutes, the heat shrinkage rate of the heat-treated flame resistant fiber is not sufficiently lowered. When the heating time exceeds 60 minutes, the rigidity of the heat-treated flame resistant fiber becomes high and it becomes difficult to process it into a sheet shape.

不活性ガスとしては、窒素、アルゴン、ヘリウム等が挙げられる。   Examples of the inert gas include nitrogen, argon, helium and the like.

熱処理は、熱処理耐炎繊維の熱収縮率を低減させるために、耐炎繊維を自由収縮させながら行うことが好ましい。   The heat treatment is preferably performed while freely shrinking the flame resistant fiber in order to reduce the heat shrinkage rate of the heat treated flame resistant fiber.

上記熱処理によって得られる熱処理耐炎繊維のアルキメデス法による繊維比重は1.35〜1.75であり、1.39〜1.70が好ましく、1.42〜1.68がより好ましい。繊維比重が1.35未満の場合、焼成時における繊維の熱収縮が大きくなり、得られる炭素繊維シート表面にウネリやシワが発生して、表面平滑性が悪化する。繊維比重が1.75を超える場合は、繊維の剛性が高くなり、シート作製時に繊維が折損してシートに毛羽立ちが生じる。   The fiber specific gravity by the Archimedes method of the heat-resistant flame-resistant fiber obtained by the said heat processing is 1.35-1.75, 1.39-1.70 are preferable and 1.42-1.68 are more preferable. When the fiber specific gravity is less than 1.35, the heat shrinkage of the fiber during firing becomes large, and undulation and wrinkles are generated on the surface of the obtained carbon fiber sheet, so that the surface smoothness is deteriorated. When the fiber specific gravity exceeds 1.75, the rigidity of the fiber becomes high, and the fiber breaks when the sheet is produced, and the sheet becomes fluffy.

また、上記熱処理によって得られる熱処理耐炎繊維の熱収縮率は2.0〜15%であり、2.5〜12%が好ましく、3.0〜10%がより好ましい。熱収縮率が15%を超える場合、焼成時の繊維収縮が大きく、炭素繊維シート表面にウネリやシワが発生して、表面平滑性が低下する。また、炭素繊維シートのシート面に沿う中央部と外縁部との厚さに差が生じ易くなり、厚さの均一性が低下する。熱収縮率が2.0%未満の場合、繊維の剛性が高くシート加工が困難になる。   Moreover, the heat shrinkage rate of the heat-resistant flame resistant fiber obtained by the said heat processing is 2.0 to 15%, 2.5 to 12% is preferable and 3.0 to 10% is more preferable. When the thermal shrinkage rate exceeds 15%, fiber shrinkage during firing is large, undulation and wrinkles are generated on the surface of the carbon fiber sheet, and surface smoothness is lowered. Moreover, it becomes easy to produce a difference in the thickness of the center part along the sheet | seat surface of a carbon fiber sheet, and an outer edge part, and the uniformity of thickness falls. When the heat shrinkage rate is less than 2.0%, the fiber has high rigidity and sheet processing becomes difficult.

本発明において熱収縮率とは、非緊張下において1000℃で10分間焼成した際の繊維の収縮率をいい、下記式(1)により算出される値をいう。   In the present invention, the heat shrinkage rate refers to the shrinkage rate of the fiber when fired at 1000 ° C. for 10 minutes under non-tension, and is a value calculated by the following formula (1).

Figure 0005489831
Figure 0005489831

熱処理耐炎繊維は製織や抄紙等の公知の方法によりシート加工されて、熱処理耐炎繊維シートが製造される。熱処理耐炎繊維シートとしては、熱処理耐炎繊維クロス、熱処理耐炎繊維フェルト、熱処理耐炎繊維ペーパー等が挙げられる。   The heat treated flame resistant fiber is processed into a sheet by a known method such as weaving or paper making to produce a heat treated flame resistant fiber sheet. Examples of the heat treated flame resistant fiber sheet include heat treated flame resistant fiber cloth, heat treated flame resistant fiber felt, heat treated flame resistant fiber paper and the like.

熱処理耐炎繊維クロスは、繊維長が30〜75mm、繊度が0.5〜3.4dtexの熱処理耐炎繊維を用いて、乾強度が16mN/dtex以上、撚り係数は150〜900回/mとなる熱処理耐炎繊維紡績糸を作製し、それを製織加工することで得られる。織組織は、平織、綾織、朱子織等のいずれでも構わない。   The heat treated flame resistant fiber cloth is a heat treated fiber having a fiber length of 30 to 75 mm and a fineness of 0.5 to 3.4 dtex, a dry strength of 16 mN / dtex or more, and a twist coefficient of 150 to 900 times / m. It is obtained by producing a flame resistant fiber spun yarn and weaving it. The weaving structure may be any of plain weaving, twill weaving, satin weaving and the like.

熱処理耐炎繊維フェルトは、繊維長20〜75mm、繊度0.5〜3.4dtexの熱処理耐炎繊維をニードルパンチ、ウォータージェット、エアージェット等でフェルト化して得られる。   The heat treated flame resistant fiber felt is obtained by forming a heat treated flame resistant fiber having a fiber length of 20 to 75 mm and a fineness of 0.5 to 3.4 dtex by using a needle punch, a water jet, an air jet or the like.

熱処理耐炎繊維ペーパーは、繊維長1〜30mm、繊度0.5〜3.4dtexの熱処理耐炎繊維とバインダーを混抄又は含浸させて得られる。バインダーとしては、後工程の焼成処理時における残炭率が0.5〜50質量%の物が用いられる。具体的には、アラミド樹脂、フェノール樹脂、水溶性熱可塑性樹脂、又は熱可塑性有機繊維等が挙げられる。熱可塑性有機繊維としては、ポリエステル繊維、ポリオレフィン繊維、ビニロン繊維等が例示される。ポリエステル繊維としては、ポリエチレンテレフタレート(PET)繊維、ポリブチルテレフタレート(PBT)繊維、ポリアリレート(PAT)繊維、及びそれらの繊維に属する共重合繊維を含む複合繊維等が例示される。ポリオレフィン繊維としては、ポリプロピレン(PP)繊維、及びそれに属する共重合物を含む複合繊維等が例示される。ビニロン繊維としては、ポリビニルアルコール(PVA)繊維、及びそれに属する共重合体を含む複合繊維等が例示される。   The heat treated flame resistant fiber paper is obtained by mixing or impregnating a heat treated flame resistant fiber having a fiber length of 1 to 30 mm and a fineness of 0.5 to 3.4 dtex and a binder. As the binder, a binder having a residual carbon ratio of 0.5 to 50% by mass during the post-baking process is used. Specifically, an aramid resin, a phenol resin, a water-soluble thermoplastic resin, a thermoplastic organic fiber, or the like can be given. Examples of the thermoplastic organic fiber include polyester fiber, polyolefin fiber, and vinylon fiber. Examples of the polyester fiber include polyethylene terephthalate (PET) fiber, polybutyl terephthalate (PBT) fiber, polyarylate (PAT) fiber, and composite fiber including copolymer fibers belonging to these fibers. Examples of the polyolefin fibers include polypropylene (PP) fibers and composite fibers including a copolymer belonging to the fibers. Examples of vinylon fibers include polyvinyl alcohol (PVA) fibers and composite fibers containing copolymers belonging to them.

上記のようにして得られる熱処理耐炎繊維シートは、面圧を付与することなく、又は1.0kPa以下、好ましくは0.1〜0.5kPaの面圧を付与しながら、不活性ガス中で焼成することにより、本炭素繊維シートとなる。面圧の付与は、好ましくは焼成中を通して、バッチプレス、間欠プレス、カレンダプレス、ベルトプレス、ローラー等への接触による接圧付与等を用いて行われる。焼成温度は1000〜2500℃が好ましく、1300〜2300℃がより好ましい。焼成温度が1000℃未満である場合、炭素繊維としての強度や電気伝導性が不足し好ましくない。焼成温度が2500℃を超える場合は、炭素繊維シートが剛直となり、強度が低下しやすい。更には、炭素微粉末が発生する等の不具合が生じやすい。   The heat-resistant flame-resistant fiber sheet obtained as described above is fired in an inert gas without applying a surface pressure or while applying a surface pressure of 1.0 kPa or less, preferably 0.1 to 0.5 kPa. By doing this, it becomes this carbon fiber sheet. The application of the surface pressure is preferably performed through firing, using contact pressure application by contact with a batch press, intermittent press, calendar press, belt press, roller, or the like. The firing temperature is preferably 1000 to 2500 ° C, more preferably 1300 to 2300 ° C. When the firing temperature is less than 1000 ° C., the strength and electrical conductivity as carbon fiber are insufficient, which is not preferable. When the firing temperature exceeds 2500 ° C., the carbon fiber sheet becomes rigid and the strength tends to decrease. Furthermore, problems such as generation of carbon fine powder are likely to occur.

熱処理耐炎繊維シートの焼成時間は10〜60分間である。   The firing time of the heat-treated flame resistant fiber sheet is 10 to 60 minutes.

以下、実施例により本発明を更に具体的に説明するが、本発明はこれら実施例に限定されるものではない。   EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

各物性の測定、評価は以下の方法によった。   Each physical property was measured and evaluated by the following methods.

[目付]
10cm角のシートを120℃、1hr乾燥した後の質量値より算出した。
[Unit weight]
The 10 cm square sheet was calculated from the mass value after drying at 120 ° C. for 1 hr.

[厚さ平均値]
10cm角のシート面を碁盤の目状に9面に区分(即ち、約3.33cm角で9面に区分)し、区分された各面の中心部におけるシートの厚さを測定し、これら9点の厚さ測定値の平均値を用いた。厚さは、直径5mmの円形圧板でシートの厚さ方向に1.2Nの荷重(61.9kPa)を負荷した時の厚さを測定した。
[Thickness average value]
The sheet surface of 10 cm square is divided into 9 planes in a grid pattern (that is, divided into 9 planes of about 3.33 cm square), and the thickness of the sheet at the center of each of the divided surfaces is measured. The average value of the point thickness measurements was used. The thickness was measured when a load of 1.2 N (61.9 kPa) was applied in the thickness direction of the sheet with a circular pressure plate having a diameter of 5 mm.

[厚さ斑]
上記9点の厚さ測定値の最大値と最小値との差を厚さ斑とした。また、厚さ斑の、厚さ平均値に対する割合を百分率(%)で表した。尚、実用的にはこの厚さ斑が40μm以下であると、各種用途に問題なく使用可能である。
[Thick spots]
The difference between the maximum value and the minimum value of the nine measured thickness values was defined as thickness spots. Moreover, the ratio with respect to the average thickness value of the thickness spots was expressed as a percentage (%). Practically, when the thickness unevenness is 40 μm or less, it can be used for various purposes without problems.

[比重]
アルキメデス法(溶媒アセトン)により測定した。
[specific gravity]
It was measured by the Archimedes method (solvent acetone).

[熱収縮率]
長さ1mの熱処理耐炎繊維をバッチ炉中(非緊張下)で窒素雰囲気下、1000℃で10分間焼成後、焼成した繊維の長さを測定し、下記式(2)により算出した。
[Heat shrinkage]
A heat-treated flame resistant fiber having a length of 1 m was baked in a batch furnace (under no tension) in a nitrogen atmosphere at 1000 ° C. for 10 minutes, and then the length of the baked fiber was measured and calculated by the following formula (2).

Figure 0005489831
Figure 0005489831

[表面平滑性]
目視で評価した。シート表面にシワや毛羽、シートの面方向にウネリが見られない場合は○、見られた場合は×とした。
[Surface smoothness]
Visually evaluated. In the case where wrinkles and fluff were not observed on the surface of the sheet and no undulation was observed in the surface direction of the sheet, the evaluation was ○.

[実施例1〜4、比較例1〜4]
原料となる前駆体繊維は、ポリアクリロニトリル(PAN)系繊維を250℃の空気中で2時間加熱して耐炎化処理することにより製造した。
[Examples 1-4, Comparative Examples 1-4]
The precursor fiber used as a raw material was manufactured by heating a polyacrylonitrile (PAN) fiber in air at 250 ° C. for 2 hours for flame resistance treatment.

この耐炎繊維を表1又は2に記載する条件により加熱して熱処理を行った。その後、この熱処理耐炎繊維を表1又は2に記載する条件によりシート加工して熱処理耐炎繊維シートを作製した。得られた熱処理耐炎繊維シートは、表1又は2に記載する条件により焼成して、炭素繊維シートを得た。得られた炭素繊維シートの評価結果を表1又は2に示した。   This flame resistant fiber was heated under the conditions described in Table 1 or 2 for heat treatment. Thereafter, the heat-treated flame resistant fiber sheet was processed according to the conditions described in Table 1 or 2 to prepare a heat treated flame resistant fiber sheet. The obtained heat-treated flame resistant fiber sheet was fired under the conditions described in Table 1 or 2 to obtain a carbon fiber sheet. The evaluation results of the obtained carbon fiber sheet are shown in Table 1 or 2.

Figure 0005489831
Figure 0005489831

Figure 0005489831
Figure 0005489831

表1に示すように、実施例1〜4においては表面平滑性の良好な炭素繊維シートが得られた。比較例1の炭素繊維シートは、耐炎繊維の比重が小さいため、炭素繊維シートにシワが発生し、良好な表面平滑性が得られなかった。比較例2の炭素繊維シートは、耐炎繊維の比重が大きいため、シートの炭素繊維が折れ、表面に毛羽が発生した。比較例3の炭素繊維シートは、耐炎繊維の収縮率が大きいため、炭素繊維シートの厚さ斑が60μmとなり、厚さの均一性が低かった。比較例4は、炭素繊維の比重が大きいために繊維が剛直であり、織物として製織できなかった。   As shown in Table 1, in Examples 1 to 4, carbon fiber sheets with good surface smoothness were obtained. In the carbon fiber sheet of Comparative Example 1, since the specific gravity of the flame resistant fiber was small, wrinkles were generated in the carbon fiber sheet, and good surface smoothness was not obtained. In the carbon fiber sheet of Comparative Example 2, since the specific gravity of the flame resistant fiber was large, the carbon fiber of the sheet was broken and fluff was generated on the surface. Since the carbon fiber sheet of Comparative Example 3 had a large shrinkage ratio of the flame resistant fiber, the thickness unevenness of the carbon fiber sheet was 60 μm, and the thickness uniformity was low. In Comparative Example 4, since the specific gravity of the carbon fiber was large, the fiber was rigid and could not be woven as a woven fabric.

Claims (4)

厚さ平均値が50〜500μmの炭素繊維ペーパーであって、該炭素繊維ペーパーの厚さの最大値と最小値との差が、該炭素繊維ペーパーの厚さ平均値の10%未満であり、該炭素繊維ペーパーの表面に毛羽を有さないことを特徴とする炭素繊維ペーパーThe thickness average value a carbon fiber paper 50 to 500 [mu] m, the difference between the maximum value and the minimum value of the thickness of the carbon fiber paper, Ri less than 10% der thickness average value of the carbon fiber paper Carbon fiber paper characterized by having no fluff on the surface of the carbon fiber paper . (a)炭素繊維の前駆体繊維である耐炎繊維を不活性雰囲気下、700〜900℃で0.1〜60分間熱処理して、アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜7.0%の熱処理耐炎繊維を得る工程と、
(b)前記熱処理耐炎繊維にバインダーを混抄又は含浸させて熱処理耐炎繊維ペーパーを得る工程と、
(c)前記熱処理耐炎繊維ペーパーを不活性雰囲気下で焼成して炭素繊維ペーパーを得る工程と、
を有する請求項1に記載の炭素繊維ペーパーの製造方法。
(A) A flame resistant fiber, which is a carbon fiber precursor fiber, is heat-treated at 700 to 900 ° C. for 0.1 to 60 minutes in an inert atmosphere, and has a fiber specific gravity of 1.35 to 1.75 and heat. Obtaining a heat-treated flame-resistant fiber having a shrinkage ratio of 2.0 to 7.0 %;
(B) a step of blending or impregnating the heat treated flame resistant fiber with a binder to obtain a heat treated flame resistant fiber paper ;
(C) firing the heat-treated flame resistant fiber paper in an inert atmosphere to obtain carbon fiber paper ;
The manufacturing method of the carbon fiber paper of Claim 1 which has these.
アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜7.0%である熱処理耐炎繊維から成る、請求項1に記載の炭素繊維ペーパー製造用の熱処理耐炎繊維ペーパーThe heat-treated flame-resistant fiber for producing carbon fiber paper according to claim 1, comprising a heat-treated flame-resistant fiber having a fiber specific gravity of 1.35 to 1.75 and a heat shrinkage rate of 2.0 to 7.0 % by Archimedes method. Paper . (a)炭素繊維の前駆体繊維である耐炎繊維を不活性雰囲気下、700〜900℃で0.1〜60分間熱処理して、アルキメデス法による繊維比重が1.35〜1.75で且つ熱収縮率が2.0〜7.0%の熱処理耐炎繊維を得る工程と、
(b)前記熱処理耐炎繊維にバインダーを混抄又は含浸させて熱処理耐炎繊維ペーパーを得る工程と、
を有する請求項3に記載の熱処理耐炎繊維ペーパーの製造方法。

(A) A flame resistant fiber, which is a carbon fiber precursor fiber, is heat-treated at 700 to 900 ° C. for 0.1 to 60 minutes in an inert atmosphere, and has a fiber specific gravity of 1.35 to 1.75 and heat. Obtaining a heat-treated flame-resistant fiber having a shrinkage ratio of 2.0 to 7.0 %;
(B) a step of blending or impregnating the heat treated flame resistant fiber with a binder to obtain a heat treated flame resistant fiber paper ;
The manufacturing method of the heat-resistant flame-resistant fiber paper of Claim 3 which has these.

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