JP4524060B2 - Antistatic polybenzazole composition for industrial materials - Google Patents

Description

【００１４】
【化２】

【００１５】
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。
【００１６】
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。
【００１７】
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。
【００１８】
添加するカーボンナノチューブはドープを合成するときにドープ原料と同時に配合しておく。良好な制電性を発現せしめるためには、カーボンナノチューブがドープ中に均一に混合分散している必要がある。ドープを重合する前に原料を投入した後８０℃以下の温度にて一旦原料同士を攪拌混合した後定法に従ってドープを調製すると良い。添加量はモノマー仕込量に対して重量分率にして０．１％以上５％未満、好ましくは１％以上３％未満である。この量より少ないと完成糸中に含有されるカーボンナノチューブが少なくなり制電性の発現が期待できない。反対に多すぎるとカーボンナノチューブの繊維中での分散製が悪くなり、繊維の色が黒みがかるため好ましくない。
【００１９】
この様にして重合されるドープを繊維状に成型する方法について述べる。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。良好な力学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、メタノール、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】
フィルムに成型する方法としては、一般的な製膜法を用いれば良い。例えばドープをプレス成形する方法。また、Ｔダイからチルロール上にキャストしたのち、延伸、凝固、水洗、乾燥して巻き上げる加工法などが上げられる。
【００２３】
制電性能を発現せしめるためにはカーボンナノチューブが均一に分散している必要がある。通常この構造はドープ中にカーボンナノチューブを均一に分散できたとき、通常の成形工程を通すことで自発的に発現することを鋭意検討の結果見出した。
【００２４】
制電性の測定は、ＪＩＳ Ｌ １０９４ 摩擦帯電圧測定法に準拠して実施した。
【００２５】
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】
（比較例１）
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３３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、巻き取り、８０℃の乾燥オーブン中で乾燥した。結果を表１に示す。
【００２７】
（実施例１、２、比較例２）
カーボンナノチューブをポリベンザゾール繊維の原料と投入添加し、予め均一混合せしめた後ドープを重合する事以外は比較例１と同じ方法で繊維を作成し繊維状の電気伝導体を得た。混合の均一性については目視にて判定した。即ち、カーボンナノチューブの黒色が均一になるまで攪拌を実施した。結果を表１に示す。
【００２８】
（実施例３）
カーボンナノチューブをポリベンザゾール繊維の原料と投入添加し、予め均一混合せしめた後ドープを重合する事以外は比較例１と同じ方法でドープを調整した。次にプレス機をを用いてプレスすることによりドープをフィルム上に成形した。さらに２０℃の水中で凝固、水洗した後８０℃のオーブン中で乾燥させた。長辺１０ｃｍ短辺８ｃｍ厚さ５００μｍのフィルムを得た。さらに得られたフィルムをスリット工程を通して幅３０ｃｍに調整してフィルム状の電気伝導体を得た。結果を表１に示す。
【００２９】
【表１】

【００３０】
上記表１より本発明の組成物は従来の繊維に比べて制電性の向上が見られ、物性上、極めて優れていることが理解される。
従って本発明に係る組成物は、従来にない優れた制電性をもつポリベンザゾール組成物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得られる。
具体的には、航空機材料用や宇宙開発用のコンポジット材料としての利用が期待できる。更に、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、等の資材はもとより、回路基板用の電気伝導体、コンピューター、航空機、ロケット用の回路用細径電線、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。
【００３１】
【発明の効果】
本発明によると、従来にない優れた制電性をもつポリベンザゾール組成物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。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polybenzazole composition having antistatic properties suitable as an industrial material.
[0002]
[Prior art]
The polybenzazole composition has more than twice the strength and elastic modulus of polyparaphenylene terephthalamide fiber, which is a representative super fiber currently on the market, and is expected as a next generation super fiber. It is known to produce fibers from a polyphosphoric acid solution of a polybenzazole polymer, for example, US Pat. No. 5,296,185 for spinning conditions, US Pat. No. 5,385,702, W094 for water washing and drying, and Technical disclosures are made in US Pat. No. 5,296,185, respectively.
[0003]
[Problems to be solved by the invention]
However, since the composition is not an electrical conductor, for example, when used in an environment where static electricity is likely to occur, static electricity accumulates and black smoke is generated. For this reason, it has been an obstacle to widely using the fibers industrially.
[0004]
Accordingly, the present inventors have intensively studied to develop a technique for easily producing an antistatic polybenzazole composition that is light, strong, and can be processed further finely.
[0005]
As a means for realizing the ultimate physical properties of the fiber, a composite made of carbon nanotube and polymer is used. In order to provide flexibility and workability, it is an essential condition that the polymer component combined with the carbon nanotubes is linear.
[0006]
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.
[0007]
The fiberization of the polymer is carried out by the method described in US Pat. No. 5,296,185 and US Pat. No. 5,357,702, and the heat treatment method is carried out by the method proposed in US Pat. No. 5,296,185. The frictional voltage was about the same as that of ordinary polymers. 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.
[0008]
That is, the present invention is an antistatic polybenzazole composition for industrial materials, comprising a polybenzazole composition containing carbon nanotubes. The antistatic polybenzazole composition as described above, wherein the content of the carbon nanotube is 0.1 to 5% by weight based on the polybenzazole. The antistatic polybenzazole composition as described above, wherein the carbon nanotube has an outer diameter of 100 nm or less and a length of 0.005 μm or more and 10 μm or less.
[0009]
[Means for Solving the Problems]
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, a spun yarn obtained by extruding a polymer dope made of polyparaphenylene benzobisoxazole, in which carbon nanotubes are uniformly dispersed and blended, from a spinneret or die into a non-solidifying gas is extracted (coagulated) in a bath. The phosphoric acid contained in the yarn or film is extracted and then dried and wound. When it is necessary to increase the elastic modulus, the heat treatment is further performed under tension at a temperature of 500 ° C. or higher.
[0010]
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. 4,453,393 (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 Pat. No. 4578432 (March 25, 1986), and the like.
[0011]
A carbon nanotube is a tubular compound consisting essentially of carbon, and the number of layers may be either single or multiple. As a production method, an arc discharge method, a vapor phase growth method, and the like are known (Japanese Patent Laid-Open No. 2001-80913). Carbon nanotubes obtained by any method may be used. The outer diameter is 100 nm or less. The length is 0.005 μm or more and 10 μm or less, preferably 1 μm or more and 5 μm or less. If the outer diameter exceeds 50 nm, the flexibility is poor, which is not preferable because the durability against bending fatigue of the finished yarn is deteriorated. If the length exceeds 10 μm, the nanotubes themselves are not oriented in the mechanical stretching direction, which is not preferable. When the length is less than 0.005 μm, the antistatic performance is not preferable.
[0012]
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 (d).
[0013]
[Chemical 1]

[0014]
[Chemical 2]

[0015]
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.
[0016]
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.
[0017]
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. A polymer consisting essentially of PBO, according to Gregory et al., US Pat. No. 5,089,591 (February 18, 1992), has a high reaction rate at high reaction rates under relatively high temperature and high shear conditions in a dehydrating acid solvent. Molecular weight is possible.
[0018]
The carbon nanotube to be added is mixed with the dope raw material when the dope is synthesized. In order to achieve good antistatic properties, the carbon nanotubes need to be uniformly mixed and dispersed in the dope. It is preferable to prepare the dope according to a conventional method after the raw materials are added before the dope is polymerized, and then the raw materials are once stirred and mixed at a temperature of 80 ° C. or lower. The addition amount is 0.1% or more and less than 5%, preferably 1% or more and less than 3%, by weight fraction with respect to the monomer charge. When the amount is less than this amount, carbon nanotubes contained in the finished yarn are reduced, and antistatic properties cannot be expected. On the other hand, if the amount is too large, the dispersion of carbon nanotubes in the fiber becomes poor, and the color of the fiber becomes dark.
[0019]
A method for molding the dope thus polymerized into a fiber will be described. The dope 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 mechanical 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]
As a method for forming the film, a general film forming method may be used. For example, a method of press-molding a dope. In addition, after casting from a T die onto a chill roll, a drawing method such as stretching, coagulation, washing with water, drying and winding up can be raised.
[0023]
In order to develop the antistatic performance, the carbon nanotubes need to be uniformly dispersed. As a result of intensive studies, it has been found that this structure usually appears spontaneously through a normal molding process when the carbon nanotubes can be uniformly dispersed in the dope.
[0024]
The antistatic property was measured in accordance with the JIS L 1094 friction band voltage measurement method.
[0025]
Hereinafter, although an example is shown, the present invention is not limited to these examples.
[0026]
【Example】
(Comparative Example 1)
Obtained by the method shown in US Pat. No. 4,453,393, 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, 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 a spinneret having a pore number of 33 After spinning at 170 ° C. and cooling the discharged yarn using cooling air at a temperature of 60 ° C., an extraction consisting of a 20% phosphoric acid aqueous solution with a spinning speed wound around a gosset roll and kept at a temperature of 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 0.1N sodium hydroxide solution. Neutralization treatment was performed. Furthermore, after washing with water in a water bath, it was wound up and dried in a drying oven at 80 ° C. The results are shown in Table 1.
[0027]
(Examples 1 and 2 and Comparative Example 2)
Fibers were prepared in the same manner as in Comparative Example 1 except that carbon nanotubes were added to and added to the raw material of polybenzazole fiber, mixed in advance, and then the dope was polymerized to obtain a fibrous electrical conductor. The uniformity of mixing was determined visually. That is, stirring was performed until the black color of the carbon nanotubes became uniform. The results are shown in Table 1.
[0028]
(Example 3)
The dope was adjusted in the same manner as in Comparative Example 1 except that carbon nanotubes were added to and added to the raw material of polybenzazole fiber, and the dope was polymerized after uniform mixing in advance. Next, dope was shape | molded on the film by pressing using a press machine. Further, it was solidified in 20 ° C. water, washed with water, and then dried in an oven at 80 ° C. A film having a long side of 10 cm, a short side of 8 cm and a thickness of 500 μm was obtained. Furthermore, the obtained film was adjusted to a width of 30 cm through a slit process to obtain a film-like electric conductor. The results are shown in Table 1.
[0029]
[Table 1]

[0030]
From Table 1 above, it is understood that the antistatic property of the composition of the present invention is improved as compared with the conventional fiber, and the physical properties are extremely excellent.
Therefore, the composition according to the present invention can easily produce a polybenzazole composition having an excellent antistatic property that has not been heretofore industrially. Effect is obtained.
Specifically, it can be expected to be used as a composite material for aircraft materials and space development. In addition to materials such as cables, tension members such as electric wires and optical fibers, ropes, etc., electrical conductors for circuit boards, thin wires for circuits for computers, aircraft and rockets, rocket insulation, rocket casing, pressure Containers, space suit strings, planetary exploration balloons, etc. aviation, space materials, impact resistant materials such as bulletproof materials, cut resistant materials such as gloves, fire clothes, heat felt, plant gaskets, heat resistant fabrics, various Heat-resistant flame-resistant members such as sealing, heat-resistant cushions, filters, belts, tires, shoe soles, ropes, hoses, rubber reinforcements, fishing lines, fishing rods, tennis rackets, table tennis rackets, badminton rackets, golf shafts, club heads, guts , Strings, sail crosses, competition (running) shoes, spiked shoes, competition (running) bicycles and Wheels, spokes, brake wires, transmission wires, sports wheelchairs and their wheels, sports-related materials such as skis, stocks, helmets, friction belts, friction materials such as clutch facings, and various building materials It can be used for a wide range of applications such as reinforcing agents and other rider suits, speaker cones, lightweight baby carriages, lightweight wheelchairs, lightweight nursing beds, lifeboats, life jackets.
[0031]
【The invention's effect】
According to the present invention, since a polybenzazole composition having an excellent antistatic property that has never been obtained can be easily produced industrially, it is highly effective as an industrial material and has a great effect of expanding the field of use. It is.

Claims (1)

An antistatic polybenzazole composition for industrial materials, comprising a polybenzazole composition containing carbon nanotubes of 0.7 wt% or more and 4.2 wt% or less with respect to polybenzazole.