JP3801734B2 - High modulus polybenzazole fiber and process for producing the same - Google Patents

Description

【００１５】
【化２】

【００１６】
実質的にＰＢＯから成るポリマーのドープを形成するための好適溶媒としては、クレゾールやそのポリマーを溶解し得る非酸化性の酸が含まれる。好適な酸溶媒の例としては、ポリ燐酸、メタンスルフォン酸及び高濃度の硫酸或いはそれ等の混合物があげられる。更に適する溶媒は、ポリ燐酸及びメタンスルフォン酸である。また最も適する溶媒は、ポリ燐酸である。
【００１７】
溶媒中のポリマー濃度は好ましくは少なくとも約７重量％であり、更に好ましくは少なくとも１０重量％、最も好ましくは１４重量％である。最大濃度は、例えばポリマーの溶解性やドープ粘度といった実際上の取り扱い性により限定される。それらの限界要因のために、ポリマー濃度は２０重量％を越えることはない。
【００１８】
好適なポリマーやコポリマーあるいはドープは公知の手法により合成される。例えばWolfe 等の米国特許第4533693 号（１９８５年８月６日）、Sybert等の米国特許第4772678 号（１９８８年９月２０日）、Harrisの米国特許第4847350 号（１９８９年７月１１日）に記載される方法で合成される。実質的にＰＢＯから成るポリマーはGregory 等の米国特許第5089591 号（１９９２年２月１８日）によると、脱水性の酸溶媒中での比較的高温、高剪断条件下において高い反応速度での高分子量化が可能である。
【００１９】
この様にして重合されるドープは紡糸部に供給され、紡糸口金から通常１００℃以上の温度で吐出される。口金細孔の配列は通常円周状、格子状に複数個配列されるが、その他の配列であっても良い。口金細孔数は特に限定されないが、紡糸口金面における紡糸細孔の配列は、吐出糸条間の融着などが発生しないような孔密度を保つ必要がある。
【００２０】
紡出糸条は十分な延伸比（ＳＤＲ）を得るため、米国特許第5296185 号に記載されたように十分な長さのドローゾーン長が必要で、かつ比較的高温度（ドープの固化温度以上で紡糸温度以下）の整流された冷却風で均一に冷却されることが望ましい。ドローゾーンの長さ（Ｌ）は非凝固性の気体中で固化が完了する長さが必要であり大雑把には単孔吐出量（Ｑ）によって決定される。良好な繊維物性を得るにはドローゾーンの取り出し応力がポリマー換算で（ポリマーのみに応力がかかるとして）２ｇ／ｄ以上が必要である。
【００２１】
ドローゾーンで延伸された糸条は次に抽出（凝固）浴に導かれる。紡糸張力が高いため、抽出浴の乱れなどに対する配慮は必要でなく如何なる形式の抽出浴でも良い。例えばファンネル型、水槽型、アスピレータ型あるいは滝型などが使用出来る。抽出液は燐酸水溶液や水が望ましい。最終的に抽出浴において糸条が含有する燐酸を99.0％以上、好ましくは99.5％以上抽出する。本発明における抽出媒体として用いられる液体に特に限定は無いが好ましくはポリベンゾオキサゾールに対して実質的に相溶性を有しない水、メタノ−ル、エタノール、アセトン等である。また抽出（凝固）浴を多段に分離し燐酸水溶液の濃度を順次薄くし最終的に水で水洗しても良い。さらに該繊維束を水酸化ナトリウム水溶液などで中和し、水洗することが望ましい。
【００２２】
製糸工程ライン中に、繊維に張力を付与する工程を設ける点が本発明の特徴部である。本処理を施す位置は、工程ライン中、抽出（凝固）浴突入以降、熱処理工程突入以前であれば任意の位置に設けることが出来る。付与する張力は、1.0GPa以上、望ましくは、2.8GPa以上にする必要がある。張力の付与法としては、一般的な工業的手法を用いればよい。例えば回転速度を変えたゴゼットロール間で張力を付与するなどの方法でよい。完全に水分を飛ばしてしまった乾燥糸に本処理を施しても効果はあるが、抽出（凝固）浴通過中や終了後、中和浴通過中や終了後、水洗浴通過中や終了後、または乾燥工程の途中など、繊維が水分や溶媒若しくは非溶媒を含んだ状態のいわゆる乾燥前繊維に張力をかけることが更に望ましい。張力を付与する時間は、0.00001 秒以上であれば何秒でも良い。この処理は張力の付与時間は極めて短時間で十分な効果を発揮する。特に未乾燥繊維において顕著である。一般に、繊維糸条が水分を失うほどに分子構造を再配列（微細構造の変化）させるのに要する時間が長くなる傾向にある。この熱処理前の張力処理に伴う分子構造の再配列は顕著に検出可能である。小角Ｘ線散乱において、凝固過程に伴うキャピラリー状のボイド構造の形成のために通常発現する強い赤道ストリークが実質的に消滅する。この分子構造の再配列を生じせしめるために付与する必要な張力には閾値が存在し、1.0GPa以上、さらに好ましくは2.8GPa〜4.2GPaの極めて高い張力が必要とされる。図１に、未乾燥状態繊維への張力付与の有無による小角Ｘ線散乱像の比較を示す。
上述した方法にて得られた繊維は、小角Ｘ線散乱において、赤道ストリーク（繊維軸に対し垂直方向のストリーク状の散乱）が現れず、かつ繊維密度が1.55ｇ／ｃｍ³ 以下のポリベンザゾール繊維となる。繊維密度が1.55ｇ／ｃｍ³ を超えると、繊維軸方向への均一な分子鎖の引き揃え効果を達成することが困難となる。好ましくは、1.52〜1.55ｇ／ｃｍ³ である。かかる分子再配列処理を施した後の繊維を熱処理することで、従来に無い高強度高弾性率を示すポリベンザゾール繊維を製造することが出来る。更に驚くべきことに、熱処理後の繊維の小角Ｘ線散乱には、例えば特開平8-325840号、S.J.Bai らPolymer, vol.33 p.2136（１９９２年）、S. KumarらPolymer, vol. 35 p.5408 （１９９１年）などで従来報告のある４点干渉や２点干渉が実質的に発現しないことが分かった。勿論赤道ストリークは存在しない。熱処理後の繊維の小角Ｘ散乱像を図２に示す。この事実は、今までに特許や文献等でも全く報告されていない。本発明で得られた微細構造は学術的にも新規な構造である。
【００２３】
［測定方法］
＜小角Ｘ線散乱の測定方法＞
小角Ｘ線散乱は、下記の方法で行う。測定に供するＸ線は、（株）リガク製ローターフレックスRU-300を用いて発生させる。ターゲットとして銅対陰極を用い、出力30kV x 30mA のファインフォーカスで運転する。光学系は点収束カメラを用い、Ｘ線はニッケルフィルターを用いて単色化する。検出器は、フジ写真フィルム（株）製イメージングプレート(FDL UR-V)を用いる。試料と検出器間の距離は200mm 乃至350mm の間の適当な距離でよい。空気などからの妨害バックグラウンド散乱を抑えるため、試料と検出器の間は、ヘリウムガスを充填する。露光時間は２時間乃至２４時間である。イメージングプレート上に記録された散乱強度信号の読みとりは、富士写真フィルム（株）製デジタルミクログラフィー(FDL5000) を用いる。得られたデータには、バックグラウンド補正を施した後等高線プロットを作製する。
【００２４】
＜密度の測定方法＞
密度の測定は、マイクロメリテックス製乾式自動密度計アキュピック（ヘリウムガスを用いたピクノメータ）を用いて計測する。
【００２５】
〔実施例〕
以下、更に実施例を示すが本発明はこれらの実施例に限定されるものではない。
【００２６】
＜実施例1-3,比較例1,3,4＞
米国特許第4533693 号に示される方法によって得られた、３０℃のメタンスルホン酸溶液で測定した固有粘度が24.4dL/gのポリパラフェニレンベンゾビスオキサゾール14.0（重量）％と五酸化リン含有率83.17%のポリ燐酸から成る紡糸ドープを紡糸に用いた。ドープは金属網状の濾材を通過させ、次いで２軸から成る混練り装置で混練りと脱泡を行った後、昇圧させ、重合体溶液温度を１７０℃に保ち、孔数１６６を有する紡糸口金から１７０℃で紡出し、温度６０℃の冷却風を用いて吐出糸条を冷却した後、ゴゼットロールに巻き付け紡糸条速度を与え、温度を２０±２℃に保った２０％の燐酸水溶液から成る抽出（凝固）浴中に導入した。引き続いて第２の抽出浴中でイオン交換水で糸条を洗浄した後、0.1 規定の水酸化ナトリウム溶液中に浸せきし中和処理を施した。更に水洗浴で水洗した後、張力付与、巻き取り、８０℃の乾燥オーブン中で乾燥し更に張力7.0g/d、温度６００℃の状態で 1.4秒間熱処理を行った。結果を表１に示す。
【００２７】
＜比較例２＞
実施例１と同じ条件で紡糸した水洗浴上がりの糸条を、張力付与、乾燥工程を省き実施例１と同じ熱処理を施した。結果を表１に示す。
【００２８】
【表１】

【００２９】
上記表１より本発明の繊維は従来の繊維に比べて強度とともに著しい弾性率の向上が見られ、物性上、極めて優れていることが理解される。同時に、特異な微細構造を有することも認められる。
【００３０】
【発明の効果】
本発明は、以上述べたようにこれまで得られなかった高強度と高弾性率を合わせ持ちかつ特異な繊維微細構造をもつポリベンザゾール繊維を工業的に容易に製造することができるため、産業用資材として実用性を高め利用分野を拡大する効果が絶大である。即ち、ケーブル、電線や光ファイバー等のテンションメンバー、ロープ、等の緊張材はもとより、ロケットインシュレーション、ロケットケイシング、圧力容器、宇宙服の紐、惑星探査気球、等の航空、宇宙資材、耐弾材等の耐衝撃用部材、手袋等の耐切創用部材、消防服、耐熱フェルト、プラント用ガスケット、耐熱織物、各種シーリング、耐熱クッション、フィルター、等の耐熱耐炎部材、ベルト、タイヤ、靴底、ロープ、ホース、等のゴム補強剤、釣り糸、釣竿、テニスラケット、卓球ラケット、バトミントンラケット、ゴルフシャフト、クラブヘッド、ガット、弦、セイルクロス、競技（走）用シューズ、スパイクシューズ、競技（走）用自転車及びその車輪、スポーク、ブレーキワイヤー、変速機ワイヤー、競技（走）用車椅子及びその車輪、スキー、ストック、ヘルメット、等のスポーツ関係資材、アバンスベルト、クラッチファーシング等の耐摩擦材、各種建築材料用補強剤及びその他ライダースーツ、スピーカーコーン、軽量乳母車、軽量車椅子、軽量介護用ベッド、救命ボート、ライフジャケット、等広範にわたる用途に使用出来る。
【図面の簡単な説明】
【図１】 未乾燥状態繊維への張力付与の有無と小角Ｘ線散乱像。（１−１）は張力を付与した場合、（１−２）は張力を付与しない場合。
【図２】 本発明のＰＢＯ繊維の特異な小角Ｘ線散乱像。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polybenzazole fiber having excellent strength and elastic modulus suitable as industrial materials and a method for producing the same.
[0002]
[Prior art]
Polybenzazole fiber has a strength and elastic modulus more than twice that of polyparaphenylene terephthalamide fiber, which is a representative super fiber currently on the market, and is expected as a next-generation super fiber.
[0003]
Conventionally, it is known to produce fibers from a polyphosphoric acid solution of a polybenzazole polymer. For example, there are US Pat. No. 5,296,185 and US Pat. No. 5,35,702 for spinning conditions, US Pat. No. 5,296,726 for water washing and drying methods, and US Pat. No. 5,296,185 for heat treatment methods.
[0004]
[Problems to be solved by the invention]
However, the elastic modulus of the high-strength polybenzazole fiber produced by the above-mentioned conventional production method is only about 290 GPa even after heat treatment at 350 ° C. or higher as described in US Pat. No. 5,296,185. Although extremely high elastic modulus has been reported in the laboratory, yarns (aggregate of filaments) that have a strength of 5.0 GPa or more but a modulus of elasticity of 290 GPa or more can suppress molecular relaxation under special spinning conditions. Except for the example realized by the above (JP-A-8-325840), an easy production technology at a level that can be called an industrial technology has not been obtained yet.
[0005]
Accordingly, the present inventors have intensively studied to develop a technique for easily producing a polybenzazole fiber having an ultimate elastic modulus as an organic fiber material.
[0006]
As means for realizing the ultimate physical properties of fibers, rigid polymers such as so-called ladder polymers have been considered, but such rigid polymers are not flexible and in order to have flexibility and processability as organic fibers. It is an essential condition that the polymer is linear.
[0007]
As shown by SGWierschke et al. In Material Research Society Symposium Proceedings Vol.134, p.313 (1989), cis-type polyparaphenylenebenzobisoxazole has the highest theoretical elastic modulus among linear polymers. . This result was confirmed by Tashiro et al. (Macromolecules.vol.24, p.3706 (1991)), and among polybenzazoles, cis-type polyparaphenylenebenzobisoxazole has a crystal elastic modulus of 475 GPa ( P. Galen et al., Material Research Society Symposium Proceedings Vol. 134, p.329 (1989)), thought to have the ultimate primary structure. Therefore, in order to obtain the ultimate elastic modulus, the theoretical consequence is to use polyparaphenylene benzobisoxazole as a polymer.
[0008]
The fiberization of the polymer is performed by the method described in US Pat. No. 5,296,185 and US Pat. No. 5,357,702, and the heat treatment is performed by the method proposed in US Pat. No. 5,296,185. The elastic modulus is 290 GPa at most, and only 61% of the crystal elastic modulus is realized. Therefore, the need for research on the improvement of these methods was felt, and it was found that the desired physical properties can be easily achieved industrially by the following methods.
[0009]
[Means for Solving the Problems]
That is, a spinning dope composed of polyparaphenylenebenzobisoxazole (PBO) and polyphosphoric acid is spun from the spinneret. Thereafter, it is produced through extraction (coagulation), neutralization, washing with water, drying, and heat treatment under tension. The yarn before completion of passing through the drying process is in a swollen state containing a coagulant such as a solvent or water inside the fiber. On the other hand, in order to improve the elastic modulus of the fiber, it is necessary to align the polymer molecular chains as uniformly as possible in the fiber axis direction. The polymer of polybenzazole fiber is difficult to align by a normal manufacturing method because of the rigidity of the molecular chain. However, in such a swollen state, since there are solvents and non-solvents between molecules, collisions between molecules are suppressed at the time of alignment, and it is eager to realize uniform high molecular chain orientation. It became clear as a result of examination. The fiber subjected to this treatment has a higher crystal orientation than that of the conventional yarn and a small non-uniform structure in the fiber axis direction. Furthermore, polybenzazole fibers having high strength and a high elastic modulus not obtained so far can be easily obtained industrially by heat-treating the fibers. Furthermore, the high-strength, high-modulus polybenzazole fibers have microstructural features that have not been obtained with previous techniques.
[0010]
The high modulus polybenzazole fiber according to the present invention exhibits a characteristic microstructure not found in the prior art. That is, it is a fiber having a very unique structure in which small-angle X-ray scattering does not show any equatorial streak, two-point interference, or four-point interference, and is uniform in the fiber axis direction and high in crystal orientation.
Such fibers have a strength of 5.0 GPa or more and an elastic modulus of 290 GPa or more, preferably a strength of 5.0 GPa or more and an elastic modulus of 350 GPa or more, or a strength of 6.2 GPa or more and an elastic modulus of 290 GPa or more. Accordingly, the present invention provides a high-strength and high-modulus polyparaphenylene benzobisoxazole fiber that has overcome the technical difficulties so far and has approached the crystal elastic modulus, and enables its industrial production. It is something to be frustrated.
[0011]
In order to express the structural features described above, the points of the present invention can be realized by a relatively simple method described below. That is, the yarn is contained by introducing a spun yarn obtained by extruding a polymer dope substantially consisting of polyparaphenylene benzobisoxazole from a spinneret into a non-solidifying gas into an extraction (coagulation) bath. After the phosphoric acid to be extracted is dried and wound up, a step of applying a tension of 1.0 GPa or more to the yarn is provided during or between the extraction (coagulation), neutralization, water washing and drying steps. Further, the heat treatment is performed under tension at a temperature of 500 ° C. or higher.
[0012]
The present invention will be further described in detail below. The polybenzazole fiber in the present invention refers to a PBO homopolymer, and a random, sequential or block copolymer with polybenzazole (PBZ) containing substantially 85% or more of a PBO component. Here, polybenzazole (PBZ) polymer is, for example, Wolf et al., “Liquid Crystalline Polymer Compositions, Process and Products” US Pat. No. 4,703,103 (October 27, 1987), “Liquid Crystalline Polymer Compositions, Process and Products” US Patent No. 4536992 (August 6, 1985), “Liquid Crystalline Poly (2,6-Benzothiazole) Compositions, Process and Products” US Pat. No. 4,533,724 (August 6, 1985), “Liquid Crystalline Polymer Compositions, Process and Products, US Pat. No. 4,533,393 (August 6, 1985), Evers “Thermooxidative-ly Stable Articulated p-Benzobisoxazole and p-Benzobisoxazole Polymers,” US Pat. No. 4,539,567 (November 16, 1982), Tsai "Method for making Heterocyclic Block Copolymer" US Patent No. 4578432 (March 25, 1986), and the like.
[0013]
The structural unit contained in the PBZ polymer is preferably selected from lyotropic liquid crystal polymers. The monomer unit consists of the monomer units described in structural formulas (a) to (h), and more preferably consists essentially of monomer units selected from structural formulas (a) to (c).
[0014]
[Chemical 1]

[0015]
[Chemical 2]

[0016]
Suitable solvents for forming a polymer dope consisting essentially of PBO include cresol and a non-oxidizing acid capable of dissolving the polymer. Examples of suitable acid solvents include polyphosphoric acid, methane sulfonic acid and high concentrations of sulfuric acid or mixtures thereof. Further suitable solvents are polyphosphoric acid and methanesulfonic acid. The most suitable solvent is polyphosphoric acid.
[0017]
The polymer concentration in the solvent is preferably at least about 7% by weight, more preferably at least 10% by weight, and most preferably 14% by weight. The maximum concentration is limited by practical handling properties such as polymer solubility and dope viscosity. Due to their limiting factors, the polymer concentration does not exceed 20% by weight.
[0018]
Suitable polymers, copolymers or dopes are synthesized by known techniques. For example, Wolfe et al., U.S. Pat. No. 4,453,393 (August 6, 1985), Sybert et al., U.S. Pat. No. 4,772,678 (September 20, 1988), Harris, U.S. Pat. No. 4,847,350 (July 11, 1989). It is synthesized by the method described in 1. Polymers consisting essentially of PBO, according to Gregory et al., US Pat. No. 5,089,591 (February 18, 1992), have a high reaction rate at high reaction rates under relatively high temperature, high shear conditions in dehydrating acid solvents. Molecular weight is possible.
[0019]
The dope polymerized in this way is supplied to the spinning section and discharged from the spinneret at a temperature of usually 100 ° C. or higher. A plurality of base pores are usually arranged in a circumferential shape or a lattice shape, but other arrangements may be used. The number of nozzle holes is not particularly limited, but the arrangement of the spinning holes on the spinneret surface needs to maintain a hole density that does not cause fusion between discharged yarns.
[0020]
In order to obtain a sufficient draw ratio (SDR), the spun yarn needs a sufficiently long draw zone length as described in US Pat. No. 5,296,185, and has a relatively high temperature (above the solidification temperature of the dope). It is desirable that the air is uniformly cooled with a rectified cooling air having a temperature equal to or lower than the spinning temperature. The length (L) of the draw zone needs to be a length that completes solidification in a non-solidifying gas, and is roughly determined by the single-hole discharge amount (Q). In order to obtain good fiber properties, the take-out stress of the draw zone needs to be 2 g / d or more in terms of polymer (assuming that only the polymer is stressed).
[0021]
The yarn drawn in the draw zone is then led to an extraction (coagulation) bath. Since the spinning tension is high, it is not necessary to consider the disturbance of the extraction bath, and any type of extraction bath may be used. For example, funnel type, water tank type, aspirator type or waterfall type can be used. The extract is preferably an aqueous phosphoric acid solution or water. Finally, 99.0% or more, preferably 99.5% or more of the phosphoric acid contained in the yarn is extracted in the extraction bath. The liquid used as the extraction medium in the present invention is not particularly limited, but is preferably water, methanol, ethanol, acetone or the like that is substantially incompatible with polybenzoxazole. Further, the extraction (coagulation) bath may be separated into multiple stages, the concentration of the phosphoric acid aqueous solution is gradually reduced, and finally washed with water. Further, the fiber bundle is desirably neutralized with an aqueous sodium hydroxide solution and washed with water.
[0022]
The feature of the present invention is that a step of applying tension to the fiber is provided in the yarn production process line. The position where this treatment is performed can be provided at any position in the process line after the entry of the extraction (solidification) bath and before the entry of the heat treatment process. The tension to be applied needs to be 1.0 GPa or more, preferably 2.8 GPa or more. A general industrial technique may be used as a method for applying tension. For example, a method of applying tension between gosset rolls with different rotation speeds may be used. Even if this treatment is applied to the dried yarn that has completely drained moisture, it is effective, but after passing through the extraction (coagulation) bath, after completion, after passing through the neutralization bath, after completion, after passing through the washing bath, and after completion, Alternatively, it is more desirable to apply tension to the so-called pre-drying fiber in a state where the fiber contains moisture, a solvent, or a non-solvent during the drying process. The time for applying the tension may be any number of seconds as long as it is 0.00001 seconds or more. This treatment exhibits a sufficient effect when the tension is applied for an extremely short time. This is particularly true for undried fibers. In general, the time required to rearrange the molecular structure (change in the fine structure) tends to increase as the fiber yarn loses moisture. The rearrangement of the molecular structure accompanying the tension treatment before the heat treatment can be remarkably detected. In small-angle X-ray scattering, the strong equatorial streak that normally appears due to the formation of a capillary void structure accompanying the solidification process substantially disappears. There is a threshold for the necessary tension applied to cause rearrangement of the molecular structure, and an extremely high tension of 1.0 GPa or more, more preferably 2.8 GPa to 4.2 GPa is required. FIG. 1 shows a comparison of small-angle X-ray scattering images depending on whether or not tension is applied to the undried fiber.
The fiber obtained by the above-described method is a polybenzazole having no equator streak (streaky scattering perpendicular to the fiber axis) in small-angle X-ray scattering and a fiber density of 1.55 g / cm ³ or less. Become fiber. When the fiber density exceeds 1.55 g / cm ³ , it is difficult to achieve a uniform molecular chain alignment effect in the fiber axis direction. Preferably, it is 1.52 to 1.55 g / cm ³ . By heat-treating the fiber after such molecular rearrangement treatment, a polybenzazole fiber exhibiting a high strength and high elastic modulus that has never been obtained can be produced. More surprisingly, small-angle X-ray scattering of the fiber after heat treatment is described in, for example, JP-A-8-325840, SJBai et al., Polymer, vol. 33 p.2136 (1992), S. Kumar et al., Polymer, vol. p.5408 (1991) and the like, it has been found that the four-point interference and the two-point interference reported in the prior art are not substantially developed. Of course, there is no equatorial streak. A small angle X-scattering image of the fiber after the heat treatment is shown in FIG. This fact has never been reported in patents or literature. The fine structure obtained by the present invention is an academically new structure.
[0023]
[Measuring method]
<Measurement method of small angle X-ray scattering>
Small angle X-ray scattering is performed by the following method. X-rays used for measurement are generated using a Rigaku Rotorflex RU-300. A copper counter-cathode is used as a target, and operation is performed with a fine focus of 30 kV x 30 mA output. The optical system uses a point converging camera, and the X-rays are monochromatic using a nickel filter. As the detector, an imaging plate (FDL UR-V) manufactured by Fuji Photo Film Co., Ltd. is used. The distance between the sample and the detector may be any suitable distance between 200 mm and 350 mm. In order to suppress disturbing background scattering from air or the like, helium gas is filled between the sample and the detector. The exposure time is 2 to 24 hours. To read the scattered intensity signal recorded on the imaging plate, digital micrography (FDL5000) manufactured by Fuji Photo Film Co., Ltd. is used. Contour plots are prepared for the obtained data after background correction.
[0024]
<Density measurement method>
The density is measured using a dry automatic density meter Accupic (pycnometer using helium gas) manufactured by Micromeritex.
[0025]
〔Example〕
Hereinafter, although an example is shown, the present invention is not limited to these examples.
[0026]
<Example 1-3, Comparative Examples 1, 3, and 4>
Obtained by the method shown in U.S. Pat. No. 4,536,393, 14.0% by weight of polyparaphenylenebenzobisoxazole having an intrinsic viscosity of 24.4 dL / g measured with a methanesulfonic acid solution at 30 ° C. and a phosphorus pentoxide content of 83.17 A spinning dope consisting of% polyphosphoric acid was used for spinning. The dope is passed through a metal mesh-like filter medium, and then kneaded and defoamed with a biaxial kneading apparatus, and then the pressure is increased to maintain the polymer solution temperature at 170 ° C., and from the spinneret having a pore number of 166 After spinning at 170 ° C. and cooling the discharged yarn using cooling air at a temperature of 60 ° C., extraction is made of a 20% aqueous phosphoric acid solution that is wound on a gosset roll to give a spinning speed and the temperature is kept at 20 ± 2 ° C. Introduced into the coagulation bath. Subsequently, the yarn was washed with ion-exchanged water in the second extraction bath, and then immersed in 0.1 N sodium hydroxide solution for neutralization. Further, after washing in a water bath, tension was applied, wound, dried in a drying oven at 80 ° C., and further heat treated for 1.4 seconds at a tension of 7.0 g / d and a temperature of 600 ° C. The results are shown in Table 1.
[0027]
<Comparative example 2>
The yarn after spinning in the washing bath spun under the same conditions as in Example 1 was subjected to the same heat treatment as in Example 1 without applying tension and drying steps. The results are shown in Table 1.
[0028]
[Table 1]

[0029]
From Table 1 above, it can be understood that the fiber of the present invention has a marked improvement in elastic modulus as well as strength compared to conventional fibers, and is extremely superior in physical properties. At the same time, it is recognized that it has a unique fine structure.
[0030]
【The invention's effect】
As described above, the present invention can easily industrially produce polybenzazole fiber having both a high strength and a high elastic modulus, which has not been obtained so far, and a unique fiber microstructure. As a material for use, the effect of increasing the practicality and expanding the field of use is tremendous. In other words, tension members such as cables, electric wires and optical fibers, ropes, and other tension materials, rocket insulation, rocket casing, pressure vessels, space suit strings, planetary exploration balloons, etc. Shock-resistant members such as materials, cut-resistant members such as gloves, fire-resistant clothing, heat-resistant felt, gaskets for plants, heat-resistant fabrics, various sealing, heat-resistant cushions, filters, heat-resistant and flame-resistant members, belts, tires, shoe soles, Rubber reinforcement for ropes, hoses, etc., fishing line, fishing rod, tennis racket, table tennis racket, badminton racket, golf shaft, club head, gut, strings, sail cross, competition (running) shoes, spiked shoes, competition (running) Bicycles and wheels, spokes, brake wires, transmission wires, competition (running) wheelchairs Sports-related materials such as wheels, skis, stocks, helmets, friction-resistant materials such as avant belts, clutch facings, various building material reinforcements and other rider suits, speaker cones, lightweight baby carriages, lightweight wheelchairs, lightweight nursing care Can be used for a wide range of applications such as beds, lifeboats, life jackets, etc.
[Brief description of the drawings]
FIG. 1 shows the presence / absence of tension applied to an undried fiber and a small-angle X-ray scattering image. (1-1) is when tension is applied, and (1-2) is when tension is not applied.
FIG. 2 is a unique small-angle X-ray scattering image of the PBO fiber of the present invention.

Claims (3)

After room temperature in imparting more tension 1.0 GPa, characterized in that the heat treatment is performed above 500 ° C., small angle X-ray scattering equatorial streak, not show any two points interference and four interference, modulus A high-modulus polybenzazole fiber characterized by having a strength of 290 GPa or more and a strength of 5.0 GPa or more. In small-angle X-ray scattering, an equator streak (streak-like scattering perpendicular to the fiber axis) does not appear, and a polybenzazole fiber having a fiber density of 1.55 g / cm ³ or less is heat-treated to give an elastic modulus of 290 GPa. As mentioned above, the manufacturing method of the high elasticity polybenzazole fiber characterized by becoming a fiber whose intensity | strength is 5.0 GPa or more. Phosphoric acid contained in yarn by introducing a dope composed of polyparaphenylene benzobisoxazole polymer and polyphosphoric acid into a non-solidifying gas from a spinneret into an extraction (coagulation) bath. In the fiber manufacturing method in which heat treatment is performed under a constant tension at a temperature of 500 ° C. or higher after washing with water and drying, after applying a tension of 1.0 GPa or higher at room temperature, a heat treatment of 500 ° C. or higher is performed. A process for producing a high-modulus polybenzazole fiber, characterized in that

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