EP1693489A1 - Polybenzazolfaser und sie enthaltendes erzeugnis - Google Patents

Polybenzazolfaser und sie enthaltendes erzeugnis Download PDF

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Publication number
EP1693489A1
EP1693489A1 EP04820271A EP04820271A EP1693489A1 EP 1693489 A1 EP1693489 A1 EP 1693489A1 EP 04820271 A EP04820271 A EP 04820271A EP 04820271 A EP04820271 A EP 04820271A EP 1693489 A1 EP1693489 A1 EP 1693489A1
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EP
European Patent Office
Prior art keywords
polybenzazole
make
yarn
filaments
yarns
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP04820271A
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English (en)
French (fr)
Inventor
Kohei c/o Toyo Boseki Kabushiki Kaisha KIRIYAMA
Hiroki c/o Toyo Boseki Kabushiki Kaisha MURASE
Yukihiro c/o Toyo Boseki Kabushiki Kaisha ABE
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Toyobo Co Ltd
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Toyobo Co Ltd
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Publication date
Priority claimed from JP2003412681A external-priority patent/JP2005171416A/ja
Priority claimed from JP2003424649A external-priority patent/JP2005179851A/ja
Priority claimed from JP2003424650A external-priority patent/JP2005179852A/ja
Priority claimed from JP2003424653A external-priority patent/JP2005178249A/ja
Priority claimed from JP2003424648A external-priority patent/JP2005179850A/ja
Priority claimed from JP2003424655A external-priority patent/JP2005179856A/ja
Priority claimed from JP2003424652A external-priority patent/JP2005179854A/ja
Priority claimed from JP2003424654A external-priority patent/JP2005179855A/ja
Priority claimed from JP2003424651A external-priority patent/JP2005179853A/ja
Application filed by Toyobo Co Ltd filed Critical Toyobo Co Ltd
Publication of EP1693489A1 publication Critical patent/EP1693489A1/de
Withdrawn legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
    • D01F6/74—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber

Definitions

  • the present invention relates to polybenzazole fibers which can still have high durability against atmospheres of high temperatures and high humidity even after yarns made thereof have had kink bands therein due to the damages in the course of post-processing for making woven fabrics, knitted fabrics, braids, ropes and cords.
  • the invention also relates to articles comprising the polybenzazole fibers, particularly spun yarns, rubber-reinforcing materials, fiber-reinforced composite materials, woven or knitted fabrics, knife-proof materials or bullet-proof vests, ropes and sail cloths.
  • polybenzazole fibers comprising a polybenzoxazole or a polybenzothiazole, or a copolymer thereof.
  • the filaments of polybenzazole are obtained by extruding a dope containing the above polymer or copolymer and an acid solvent through a spinneret, dipping the resulting semi-solid filaments in a fluid for solidifying them (water, or a mixture of water and an inorganic acid) to solidify them, thoroughly washing the solid filaments in a water bath to remove most of the solvent therefrom, allowing the filaments to pass through a bath holding an aqueous solution of an inorganic base to thereby neutralize the acid which has not been extracted and still remained in the filaments, and drying the same.
  • a fluid for solidifying them water, or a mixture of water and an inorganic acid
  • Polybenzazole fibers have been variously applied, because they are excellent in mechanical properties such as strength and also have high heat resistance. Lately, the polybenzazole fibers are expected to have further improved performance. Particularly desired are such polybenzazole fibers that can still have high durability against atmospheres of high temperatures and high humidity even after yarns made thereof have had kink bands therein due to the damages in the course of post-processing for making articles comprising the same, such as woven fabrics, knitted fabrics, braids, ropes and cords. In other words, such polybenzazole fibers are earnestly desired that can sufficiently maintain the strength thereof even after exposed to atmospheres of high temperatures and high humidity over long periods of time.
  • spun yarns made of the polybenzazole fibers are known.
  • spun yarns are demanded to have further improved performance.
  • Particularly desired are such polybenzazole fibers that can still have durability against atmospheres of high temperatures and high humidity even after yarns made of the same have had kink bands therein due to damages which occur in the course of post-processing for making woven or knitted fabrics, braids, ropes, cords, etc. of such yarns.
  • such polybenzazole fibers are strongly demanded that can sufficiently maintain the strength thereof even after exposed to atmospheres of high temperatures and high humidity over long periods of time.
  • nylon fibers, polyester fibers, glass fibers and steel fibers have been mainly used as rubber-reinforcing materials for tires, hoses, belts and the like.
  • aromatic polyamide fibers having high strength and high elastic modulus such as KEVLAR
  • KEVLAR aromatic polyamide fibers having high strength and high elastic modulus
  • the use of the polybenzazole fibers as rubber-reinforcing materials have attracted keen public attentions, because the polybenzazole fibers have far higher strength and elastic modulus and higher heat resistance and dimensional stability than the aromatic polyamide fibers.
  • investigations have been made on the use of the polybenzazole fibers as rubber-reinforcing fibers which are required to have still higher strength and heat resistance that the organic fibers conventionally used in the field of rubber materials can not possess.
  • Fibers have hitherto been used in fiber-reinforced composite materials. Recently, composite materials comprising carbon fibers or aramid fibers have been developed in order to improve the strength of the composite materials and reduce the weight thereof, and such composite materials have been practically used. Carbon fibers, however, have a problem in their poor impact resistance and fragility, although having very excellent dynamical performance. Aramid fibers have relatively high impact resistance, but have a lower elastic modulus than the carbon fibers and thus are poor in reinforcing effect. Under these circumstance, fiber-reinforced composite materials comprising the polybenzazole fibers are expected as the products of the next generation, since they are excellent in both of impact resistance and elastic modulus, exhibiting a superior reinforcing effect over the carbon fibers.
  • the fiber-reinforced composite materials comprising the polybenzazole fibers are demanded to have further improved performance.
  • a fiber-reinforced composite material which comprises such polybenzazole fibers that can sufficiently maintain the strength thereof when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the polybenzazole fibers have high mechanical properties such as strength and elastic modulus, and therefore are used as fibrous materials for protective materials, protective clothes and industrial materials.
  • woven or knitted fabrics comprising the polybenzazole fibers are demanded to have further improved performance.
  • a woven or knitted fabric comprising such polybenzazole fibers that can sufficiently maintain the strength thereof when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • aramid fibers have been used to make knife-proof materials or bullet-proof vests, and recently, knife-proof materials or bullet-proof vests made of high strength polyethylene fibers have been developed and put into practical use.
  • the knife-proof materials or bullet-proof vests made of the aramid fibers require lots of the fibers to exhibit the desired protective performance, and thus are thick and heavy in weight and are uncomfortable to wear. Therefore, ones can not always wear them.
  • knife-proof materials or bullet-proof vests made of high strength polyethylene fibers are reduced in weight but not in thickness because of the small specific gravity of the fibers.
  • knife-proof materials or bullet-proof vests made of the polybenzazole fibers can exhibit superior protective performance over the knife-proof materials or bullet-proof vests made of the aramid fibers and the high strength polyethylene fibers, and are expected as thin and light weight knife-proof materials or bullet-proof vests of the next generation.
  • the knife-proof materials or bullet-proof vests made of the polybenzazole fibers are demanded to have further improved performance.
  • a knife-proof materials or bullet-proof vest made of such polybenzazole fibers that can sufficiently maintain the strength thereof when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the polybenzazole fibers have high mechanical properties such as strength and also have high heat resistance as mentioned above, they have been widely used in ropes, including yacht ropes, which are required to have strength and abrasion resistance.
  • the polybenzazole fibers are susceptible to mechanical damages in the course of manufacturing of ropes, since they have very highly oriented molecular chain structures.
  • Sail cloths comprising the polybenzazole fibers also have been widely used.
  • yacht sails for use in yacht races are demanded to have high tensile resistance and high tensile strength so as not to permit their designed shapes to deform due to winds.
  • a sail cloth is dominantly used that is made by sandwiching a woven fabric or a scrim which comprises fibers having high strength and a high elastic modulus, between two films of polyester or the like to form their lamination, and molding the lamination into the sail cloth.
  • a method of making a yacht sail as an integral three-dimensional molded article has been developed. Such an integral three-dimensional molded article is also included in the scope of the sail cloth referred to in the description of the present invention.
  • the yacht sails comprising the polybenzazole fibers are demanded to have further improved performance.
  • a yacht sail made of such polybenzazole fibers that can sufficiently maintain the strength thereof when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the present invention has been developed under the foregoing circumstances, and an object of the invention is to provide polybenzazole fibers which show less decrease in strength, even after yarns made thereof have had kink bands therein due to damages thereof, and even after the fibers have been exposed to atmospheres of high temperatures and high humidity over long periods of time.
  • Another object of the present invention is to provide articles comprising the polybenzazole fibers, such as spun yarns, woven or knitted fabrics, rubber-reinforcing materials, fiber-reinforced composite materials, ropes, sail cloths, and knife-proof materials or bullet-proof vests.
  • polybenzazole fibers such as spun yarns, woven or knitted fabrics, rubber-reinforcing materials, fiber-reinforced composite materials, ropes, sail cloths, and knife-proof materials or bullet-proof vests.
  • the present invention provides the followings.
  • the polybenzazole fibers according to the present invention means fibers which comprise a polybenzazole polymer.
  • the polybenzazole polymer (hereinafter referred to as PBZ) is at least one polymer selected from the group consisting of polybenzoxazole (hereinafter referred to as PBO), polybenzothiazole (hereinafter referred to as PBT) and polybenzimidazole (hereinafter referred to as PBI).
  • PBO means a polymer which contains an oxazole ring bonded to an aromatic group which is not necessarily a benzene ring.
  • Examples of PBO include lots of polymers each of which comprises a unit of a plurality of oxazole rings bonded to poly(p-phenylenebenzbisoxazole) or an aromatic group. Analogous structures are also applied to PBT and PBI.
  • Examples of the polybenzazole polymer of the present invention also include optional mixtures of PBO, PBT and PBI, and block or random copolymers each of which comprises at least two of PBO, PBT and PBI.
  • the structural unit in the PBZ polymer is preferably selected from lyotropic liquid crystalline polymers which form liquid crystals in mineral acids at specified concentrations.
  • a polymer comprises a monomer unit of any of the following structural formulas (a) to (f):
  • the polybenzazole fibers can be manufactured from a dope containing a PBZ polymer.
  • a suitable solvent for preparing this dope cresol or a non-oxidizing acid capable of dissolving the polymer is used.
  • Preferred examples of the non-oxidizing acid include polyphosphoric acid, methanesulfonic acid, highly concentrated sulfuric acid, and mixtures thereof. Above all, polyphosphoric acid and methanesulfonic acid are preferred, and polyphosphoric acid is especially preferred.
  • the concentration of the polymer in the dope is preferably at least about 7 mass %, more preferably at least 10 mass %, particularly at least 14 mass %.
  • the maximum concentration of the polymer is limited depending on the practical handling ease of the dope, for example, the solubility of the polymer or the viscosity of the dope. Because of such restrictive factors, the concentration of the polymer is generally not higher than 20 mass %.
  • a suitable polymer or copolymer and a suitable dope can be prepared by any of known methods, for example, described in the publications of U.S. Patent No. 4,533,693 by Wolfe et al. (August 6, 1985), U.S. Patent No. 4,772,678 by Sybert et al. (September 22, 1988), U.S. Patent No. 4,847,350 by Harris (July 11, 1989) and U.S. Patent No. 5,089,591 by Gregory et al. (February 18, 1992).
  • a suitable monomer is reacted in a non-oxidizing and dehydrating acid solution under a non-oxidizing atmosphere, while being stirred at high speed under a high shearing condition, at a temperature which is increased stepwise or at a constant rate from about 60°C to about 230°C, to thereby form a dope.
  • the dope thus obtained is extruded through a spinneret, and the resulting semi-solid filaments are drawn long in an air to thereby form solid filaments.
  • the preferred methods therefor are described in the above literature and the publication of U.S. Patent No. 5,034,250.
  • the dope extruded through the spinneret is allowed to pass through a space between the spinneret and the washing bath. This space is called an air gap, and is generally charged with a gas such as an air, nitrogen, argon, helium, carbon dioxide or the like, or may be charged with a liquid which does not dissolve the solvent or react with the dope.
  • the filaments resulting from the spinning are washed so as not to be excessively drawn, and a part of the solvent is removed.
  • the filaments are further washed and neutralized with a suitable inorganic base such as sodium hydroxide, calcium hydroxide, potassium hydroxide or the like to thereby remove most of the solvent.
  • the washing herein referred to means that the fibers or the filaments are allowed to contact a liquid which is compatible with a mineral acid dissolving the polybenzazole polymer and which does not serve as a solvent for the polybenzazole polymer, to thereby remove the acid solvent from the dope.
  • a preferable washing liquid water or a mixture of water with an acid solvent is used.
  • the filaments are washed until the concentration of the residual mineral acid reached 8,000 ppm or less, preferably 5,000 ppm or less. After that, the filaments are dried and heat-treated, and if needed, are wound up.
  • organic pigment which has heat resistance as high as a thermal decomposition temperature of 200°C or higher and which is dissolved in a mineral acid
  • organic pigments that can be left to remain in the fibers or filaments when added in the course of the polymerization or added to a polymer dope and involved in the spinning from the such a dope.
  • organic pigments include insoluble azo pigments, condensed azo pigments, color lakes, isoindolinones, isoindolines, dioxazines, perinones and/or perylenes, phthalocyanines, quinacridones and the like.
  • perinones and/or perylenes examples include bisbenzimidazo[2,1-b:2',1',i]benzo[1mn][3,8]phenanthroline-8,17-dione, bisbenzimidazo[2,1-b:1',2'-j]benzo[1mn] [3,8]phenanthroline-6,9-dione, 2,9-bis(p-methoxybenzyl)anthora[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetron, 2,9-bis(p-ethoxybenzyl)anthora[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetron, 2,9-bis(3,5-dimethoxybenzyl)anthora[2,1,9-def:6,5,10-d'e'f']diiso
  • any of phthalocyanines that have phthalocyanine backbones may be used, independently of the presence or absence of a metal at the center of the ligand and the kind of an atom.
  • Specific examples of these compounds are 29H,31H-phthalocyanate(2-)-N29,N30,N31,N32 copper, 29H,31H-phthalocyanate(2-)-N29,N30,N31,N32 iron, 29H,31H-phthalocyanate-N29,N30,N31,N32 cobalt, 29H,31H-phthalocyanate(2-)-N29,N30,N31,N32 copper, oxo(29H,31H-phthalocyanate(2-)-N29,N30,N31,N32),(SP-5-12) titanium, etc.
  • the backbone of each of these phtalocyanines may have at least one substituent such as a halogen atom, methyl group, methoxy group or the like.
  • Examples of the quinacridones include 5,12-dihydro-2,9-dimethylquino[2,3-b]acridine-7,14-dione, 5,12-dihydroquino[2,3-b]acridine-7,14-dione, 5,12-dihydro-2,9-dichloroquino[2,3-b]acridine-7,14-dione, 5,12-dihydro-2,9-dibromoquino[2,3-b]acridine-7,14-dione, etc. Each of these quinacridones may be used alone or in combination.
  • each of the above perylenes, perinones, phthalocyanines and quinacridones may be used in combination with at least another one or more selected therefrom.
  • the organic compound may be added in any of the steps for the polymerization of polybenzazole, or may be added to a polymer dope obtained after completion of the polymerization.
  • the organic pigment may be added together with the starting materials for polybenzazole, or may be added in some stages or at an optional point of time during the reaction which proceeds while the reaction temperature is being raised at an optional rate. Otherwise, the organic pigment may be added to the reaction system after completion of the polymerization, and stirred and mixed into the reaction system.
  • the most distinguishing feature of the polybenzazole fibers of the present invention is that a yarn made of the polybenzazole fibers by twisting at a twist coefficient of 30 can have a strength retention of 80% or more after exposed to an atmosphere of 80°C and 80RH% for 240 hours.
  • the polybenzazole fibers of the present invention shows a strength retention of 80% or more, defined by the equation of ( a / b ) X 100.
  • the notation a means strength [cN/dtex] measured as follows.
  • the filaments are S-wise twisted until the twist coefficient can be 30, to thereby make a S-twisted yarn, which is then left to stand alone for 30 seconds.
  • the yarn is then S-wise untwisted until the twist coefficient is decreased to 6.
  • the untwisted yarn is exposed to an atmosphere of 80°C and 80 RH% for 240 hours, and is taken out to an atmosphere of a room temperature to measure the strength thereof.
  • the notation b means strength [cN/dex] measured as follows.
  • the filaments are S-wise twisted until the twist coefficient can be 30, to thereby make a S-twisted yarn, which is then left to stand alone for 30 seconds.
  • the yarn is then S-wise untwisted until the twist coefficient is decreased to 6. Then, the strength of the untwisted yarn is measured.
  • the strength retention (%) of the polybenzazole fibers of the present invention is preferably 80 to 100%, more preferably 82 to 100%, still more preferably 84 to 100%, far more preferably 85 to 100%, specifically 80 to 99%, and more specifically 80 to 98%, still more specifically 84 to 98%.
  • kink bands occur in directions vertically to the axial directions of the polybenzazole fibers when a bending stress is applied to the polybenzazole fibers. While the degrees of the kink bands differ depending on the kinds of post processing, kink bands usually occur in fibers which have undergone post processing. Kink bands also occur in fibers which are simply twisted, if the number of twists is increased.
  • the polybenzazole fibers having had kink bands therein show larger decrease in the strength thereof when exposed to an atmosphere of high temperature and high humidity over a long period of time, as compared with polybenzazole fibers having no kink band therein.
  • the polybenzazole filaments containing the organic pigment show higher durability against an atmosphere of high temperature and high humidity, namely, shows a less decrease in the strength thereof when exposed to such an atmosphere over a long period of time.
  • the yarns of the polybenzazole fibers which are damaged to have kink bands therein in the course of the post processing for making woven fabrics, knitted fabrics, brads, ropes, cords or the like show high durability against atmospheres of high temperatures and high humidity.
  • the polybenzazole fibers of the present invention have a stoichiometric ratio of an inorganic base to a mineral acid, remaining in the fibers, of 0.8 to 1.4 : 1.
  • a stoichiometic ratio of the inorganic base to the mineral acid in the fibers is too small, the pH inside of the fibers extremely inclines to the acidic side, which accelerates the hydrolysis of the PBZ molecules and lowers the strength of the fibers. This tendency becomes more remarkable in the polybenzazole fibers having kink bands therein, as compared with polybenzazole fibers having no kink band therein.
  • the polybenzazole fibers having kink bands therein show larger decrease in strength when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the stoichiometic ratio of the inorganic base to the mineral acid in the fibers is too large, the pH inside of the fibers extremely inclines to the basic side, which accelerates the hydrolysis of the PBZ molecules and lowers the strength of the fibers. This tendency becomes more remarkable in the polybenzazole fibers having kink bands therein, as compared with polybenzazole fibers having no kink band therein.
  • the polybenzazole fibers having kink bands therein show larger decrease in strength when exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the stoichiometric ratio of the inorganic base to the mineral acid, remaining in the fibers is preferably 0.8 to 1.4 : 1, more preferably 1.0 to 1.3 : 1. Desirably, this stoichiometic ratio can be found in any portions of the fibers.
  • a guide oiling system, showering system, dipping system or the like is employed as the method of neutralizing the fibers with the inorganic base in the washing step. The method, however, is not limited to these.
  • the content of the above organic pigment in the polybenzazole fibers of the present invention is preferably 2 to 8 mass%, more preferably 3 to 6 mass%.
  • this content is too low, the effect of the organic pigment in the fibers becomes poor: namely, the effect of improving the durability of the fibers having had kink bands therein, specifically, the effect of suppressing the lowering of the strength of the fibers when such fibers have been exposed to an atmosphere of high temperature and high humidity over a long period of time, becomes poor.
  • this content is too large, the fineness of the polybenzazole filaments becomes larger, and such filaments have uneven thickness, which lowers the initial strength of the filaments.
  • this content is in the range of 2 to 8 mass%, the initial strength of the filaments does not decrease due to the presence of the organic pigment in the filaments, and the spinnable property of the dope is sufficient. Thus, smooth spinning can be maintained without any filament breakage. This may be because the pigment added is dissolved in the mineral acid and thus also still dissolved in the polymer dope. However, this speculation does not restrict the present invention in any way.
  • the polybenzazole fibers of the present invention has an average diameter D of 5 to 22 ⁇ m, more preferably 10 to 20 ⁇ m, as a single filament.
  • the average strength of the polybenzazole fibers is preferably 4.5 GPa or more, more preferably 5.0 to 8.0 GPa, provided that the length of the fiber is 100 mm.
  • the polybenzazole fibers of the present invention preferably contain the organic pigment therein, as mentioned above. Therefore, sufficient control is needed to prevent the unevenness in the diameters of the fibers.
  • the coefficient of variation CV (a standard deviation/an average value) of the diameters of a single polybenzazole filament of the present invention, measured at 10 mm intervals over a length of 500 mm, is preferably 0.08 or less, more preferably 0.06 or less. When the coefficient of variation CV is too large, a stress tends to concentrate on the thin portion of the fiber, so that the fiber is easily broken.
  • the polybenzazole fibers of the present invention show high durability against an atmosphere of high temperature and high humidity, and thus are variously and suitably used in the following articles.
  • the polybenzazole fibers of the present invention are suitably used in spun yarns, rubber-reinforcing materials, fiber-reinforced composite materials, woven or knitted fabrics, knife-proof materials or bullet-proof vests, ropes, sail cloths and the like.
  • the polybenzazole fibers of the present invention are suitably used in spun yarns, especially, spun yarns for use in fibrous structures of industrial materials for protective materials or protective clothing such as fireman uniforms, fire-resistant clothing and working wears, conveyer materials, cushion materials, coating protective materials, etc., which are all required to have high strength and high heat resistance.
  • the spun yarns of the present invention include composite spun yarns blended with other kinds of fibers.
  • other kinds of fibers natural fibers, organic fibers, metal fibers, inorganic fibers, mineral fibers and the like may be used.
  • the method of blending fibers and the forms of yarns are not limited, and the generic method using opener and scutcher may be employed, or the composite yarn may be in the form of a yarn having a core-in-sheath structure.
  • the polybenzazole fibers of the present invention can be suitably used as rubber-reinforcing materials for tires, belts and hoses.
  • the polybenzazole fibers for use in rubber-reinforcing cords may be made into a single twist yarn or a two folded twist yarn with a ring twisting machine or the like, in order to improve the fatigue resistance.
  • the twist coefficient (K) may be 10 to 100.
  • the polybenzazole fibers may be surface-treated with corona or plasma. Further, a compound reactive with the surfaces of the polybenzazole fibers or the corona-treated surfaces of the polybenzazole fibers may be added to the polybenzazole fibers. To otherwise improve the adhesivity with rubber, the polybenzazole fibers may be subjected to a dipping treatment.
  • each of the following liquids may be generally used alone or in combination so as to treat the fibers in one stage or two or more stages, although any other method may be applicable: (A) an aqueous dispersion of an epoxy resin, (B) an aqueous dispersion of a blocked isocyanate, (C) an aqueous dispersion of a rubber latex, and (D) a liquid mixture of a resorcin/formaldehyde resin and a rubber latex (RFL).
  • A an aqueous dispersion of an epoxy resin
  • B an aqueous dispersion of a blocked isocyanate
  • C an aqueous dispersion of a rubber latex
  • RTL rubber latex
  • the polybenzazole fibers of the present invention can be suitably used in composite material.
  • the composite material comprising the polybenzazole fibers of the present invention may be in any form of an unidirectionally reinforced material, a pseudoisotropic laminated layer and a fabric laminated layer.
  • a matrix resin there may be used any of thermosetting resins such as an epoxy resin and a phenol resin, super engineering plastics such as PPS and PEEK, and general-purpose thermoplastic resins such as PE, PP and polyamide.
  • the polybenzazole fibers of the present invention can be suitably used in woven or knitted fabrics, particularly for protective materials for fireman uniforms, fire resistant clothing and working wears, and protective clothing which are required to have high strength and high heat resistance, and woven or knitted fabrics for industrial materials for use in conveyer materials, cushion materials and coating protective materials which are required to have high strength and high heat resistance.
  • the woven or knitted fabrics of the present invention include composite woven or knitted fabrics in combination with other kinds of fibers.
  • fibers natural fiber, organic fibers, metal fibers, inorganic fibers, mineral fibers and the like may be used.
  • the combining method is not particularly limited.
  • the kinds of the woven fabrics include union cloth, double woven cloth, lip stop, etc.
  • the kinds of the knitted fabrics include union knitting, double knitting, tubular knitting, weft knitting, warp knitting, Raschel knitting, etc.
  • the fiber bundles composing the woven or knitted fabric are not particularly limited, and examples thereof include monofilaments, multifilaments, twisted yarns, twisted union yarns, covering yarns, spun yarns, stretch broken yarns, yarns having a core-in-sheath structure, braids, etc.
  • the polybenzazole fibers of the present invention can be suitably used in knife-proof materials for vests and gloves.
  • the knife-proof material according to the present invention comprises a lamination of woven fabrics made of the polybenzazole fibers.
  • As the texture of the woven fabric any of a plain weave fabric, a twill fabric and other textures generally used in fabrics may be employed.
  • a plain weave fabric or a twill fabric in which yarns are hard to move is selected to attain higher knife-proof performance.
  • the fineness of the polybenzazole fibers for use in the knife-proof material according to the present invention is as low as 600 dtex or less, preferably 300 dtex or less, higher knife-proof performance can be attained.
  • the density of yarns in a woven fabric for use in a knife-proof material of the present invention is preferably 30/25 mm or more, more preferably 50/25 mm or more. When this density is low, the yarns tend to move, so that sufficient knife-proof performance sometimes can not be obtained.
  • the weight of the fabric is preferably 100 g/m 2 or more, more preferably 150 g/m 2 or more, in order to achieve higher knife-proof performance.
  • a part or a whole of the fabric of the present invention may be coated with or impregnated with a resin.
  • the knife-proof material of the present invention is a lamination of such fabrics. Otherwise, such fabrics may be sewn integrally with a highly strong machine sewing thread for use as the knife-proof material.
  • the polybenzazole fibers of the present invention can be suitably used in a bullet-proof vest.
  • the bullet-proof vest according to the present invention is made of a lamination of fabrics comprising the polybenzazole fibers.
  • the texture of the woven fabric may be any of a plain weave fabric, a twill fabric and other textures generally employed in fabrics.
  • a plain weave fabric or a twill fabric in which yarns are hard to move is employed to attain higher bullet-proof performance.
  • the fineness of the polybenzazole fibers for use in the bullet-proof vest according to the present invention is as low as 1,110 dtex or less, preferably 600 dtex or less, higher bullet-proof performance can be attained.
  • the density of yarns in a woven fabric for use in a bullet-proof vest of the present invention is preferably 40/25 mm or less.
  • the weight of the fabric is preferably 200 g/m 2 or less, more preferably 150 g/m 2 , in order to achieve higher bullet-proof performance.
  • the bullet-proof vest of the present invention is made of a lamination of such fabrics. Otherwise, such fabrics may be sewn integrally with a highly strong machine sewing thread for use as the bullet-proof vest.
  • the polybenzazole fibers of the present invention can be suitably used in sail cloths.
  • a sail cloth according to the present invention can be made of the polybenzazole fibers in combination with other high strength fibers such as polyethylene fibers, para-aramide fibers, wholly aromatic polyester fibers or carbon fibers.
  • a sail cloth is reinforced in complicated directions.
  • it is important to improve the durability of the polybenzazole fibers in the fiber axial direction, namely, the strength retention thereof when the polybenzazole fibers are exposed to an atmosphere of high temperature and high humidity over a long period of time.
  • the durability of a filament against an atmosphere of high temperature and high humidity was evaluated based on the retention of the tensile strength of the filament found after a storage test under an atmosphere of high temperature and high humidity, relative to the tensile strength thereof found before the same test.
  • sample filaments twisted by the foregoing method (S-twisted yarn having a twist coefficient of 6), were wound onto a resinous bobbin with a diameter of 10 cm, and then were stored in an air-conditioned container under an atmosphere of high temperature and high humidity, and then were removed from the container.
  • Untreated filaments were subjected to a tensile test at a room temperature to measure the tensile strength thereof, which was expressed as a (cN/dtex).
  • the sample twisted by the foregoing method (the S-twisted yarn having a twist coefficient of 6) was subjected to a tensile test at a room temperature to measure the tensile strength thereof, which was expressed as b (cN/dtex).
  • the strength retention was determined by dividing the value a by the value b and multiplying the resultant quotient by 100.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used in the above storage test.
  • the sample was stored at a temperature of 80°C and a relative humidity of 80% for 240 hours in the air-conditioned container which was perfectly shielded from light.
  • the tensile strength was measured with a tensile tester (AG-50KNG manufactured by SHIMADZU CORPORATION) according to the procedure of JIS-L1013.
  • the concentration of the residual phosphorus in the filament was determined by a colorimetric analysis according to the molybdenum blue method, after the sample had been subjected to a wet decomposition.
  • the concentration of the residual sodium in the filament was determined as follows: the sample was carbonized and incinerated, and the resulting ash was dissolved in an acid to form a 1.2N-HCl solution, from which the concentration of the residual sodium was determined by the atomic absorption method.
  • the diameter of a filament may be measured by an optical means or by a mechanical means such as a micrometer.
  • an optical means such as a scanning electron microscope (SEM), a laser type outer diameter measuring apparatus or the like is preferable.
  • SEM scanning electron microscope
  • the diameters of as many single filaments it is needed to measure the diameters of as many single filaments as possible: the diameters of at least 5%, preferably 7% of the number of all filaments are measured.
  • the variation in the thickness of a polybenzazole filament in the lengthwise direction is larger than the variation in the thickness of polybenzazole filaments relative to each of the polybenzazole filaments.
  • the thickness of a filament in the lengthwise direction is measured at 25 mm or less intervals at most, preferably 12 mm or less intervals.
  • this interval is relatively long, there is a danger of missing the measurement of the diameter of a narrow and neck-in portion of the filament.
  • the variation in the diameter of a filament is very small when the measuring interval is less than 5 mm.
  • the method of measuring the diameter of a single filament at 10 mm intervals over the 500 mm length of the filament is employed in the present invention.
  • the diameter of a single filament is measured at its several portion, using a scanning electron microscope (SEM) of a magnification of 5,000, and a standard deviation for assuming the average value and the normal distribution of the measured diameters is calculated, and a coefficient of variation (CV) is calculated by the following equation, using the standard deviation.
  • SEM scanning electron microscope
  • CV coefficient of variation
  • the durability of a sail cloth under an atmosphere of high temperature and high humidity was evaluated as follows.
  • a sample of a sail cloth was stored in a container conditioned constantly at a high temperature and a high humidity. After that, the sample was taken out to a laboratory in a standard state (the temperature: 20 ⁇ 2°C, and the relative humidity: 65 ⁇ 2%), and was then subjected to a tensile test within 30 minutes thereafter, so that the retention of the tensile strength of the sample after the exposure to the atmosphere of high temperature and high humidity, relative to the tensile strength thereof before the same exposure was evaluated.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used for the storage test under the atmosphere of high temperature and high humidity.
  • the storage test was continued for 240 hours in the above air-conditioned container which was perfectly shielded from light and kept constant at 80°C and 80%RH.
  • the tensile strength of the sample with a width of 2.5 cm was measured with a tensile tester (AG-50KNG manufactured by SHIMADZU CORPORATION) according to the procedure of JIS-L1096.
  • the durability of a sample of a rubber-reinforcing cord or a composite material under an atmosphere of high temperature and high humidity was evaluated as follows.
  • the sample was stored in a container conditioned constantly at a high temperature and a high humidity. After that, the sample was taken out to a laboratory in a standard state (the temperature: 20 ⁇ 2°C, and the relative humidity: 65 ⁇ 2%), and was then subjected to a tensile test within 30 minutes thereafter, so that the retention of the tensile strength of the sample after the exposure to the atmosphere of high temperature and high humidity, relative to the tensile strength thereof before the same exposure was evaluated.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used for the storage test under the atmosphere of high temperature and high humidity.
  • the storage test was continued for 240 hours in the above air-conditioned container which was perfectly shielded from light and kept constant at 80°C and 80%RH.
  • the tensile strength of the sample was measured with a tensile tester (AG-50KNG manufactured by SHIMADZU CORPORATION) according to the procedure of JIS-L1013.
  • the durability of a high strength fiber rope which was not subjected to the foregoing twisting process was evaluated.
  • the evaluation of the durability of the same under an atmosphere of high temperature and high humidity was made as follows.
  • the rope was stored in a container conditioned constantly at a high temperature and a high humidity. After that, the rope was taken out to a laboratory in a standard state (the temperature: 20 ⁇ 2°C, and the relative humidity: 65 ⁇ 2%), and was then subjected to a tensile test within 30 minutes thereafter, so that the retention of the tensile strength of the rope after the exposure to the atmosphere of high temperature and high humidity, relative to the tensile strength thereof before the same exposure was evaluated.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used for the storage test under the atmosphere of high temperature and high humidity. The storage test was continued for 240 hours in the above air-conditioned container which was perfectly shielded from light and kept constant at 80°C and 80%RH. The strength retention of the rope was determined by measuring the tensile strengths of the rope found before and after the storage test, dividing the tensile strength after the storage test by the tensile strength before the same, and multiplying the quotient by 100.
  • the durability of a sample of a woven or knitted fabric under an atmosphere of high temperature and high humidity was evaluated as follows.
  • the sample was stored in a container conditioned constantly at a high temperature and a high humidity. After that, the sample was taken out to a laboratory in a standard state (the temperature: 20 ⁇ 2°C, and the relative humidity: 65 ⁇ 2%), and was then subjected to a tensile test within 30 minutes thereafter, so that the retention of the tensile strength of the sample after the exposure to the atmosphere of high temperature and high humidity, relative to the tensile strength thereof before the same exposure was evaluated.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used for the storage test under the atmosphere of high temperature and high humidity.
  • the storage test was continued for 240 hours in the above air-conditioned container which was perfectly shielded from light and kept constant at 80°C and 80%RH.
  • the tensile strength of the woven fabric was measured according to the procedure of JIS-L1096, with a tensile tester (AG-50KNG manufactured by SHIMADZU CORPORATION), and the tensile strength of the knitted fabric was measured according to the procedure of JIS-L1018, with the same tensile tester.
  • Filaments were unwound horizontally so as not to be twisted, and allowed to contact the surfaces of five stainless steel cylinders of ⁇ 100 mm, alternately, so as to be opened.
  • the opened filaments were allowed to contact a curved die which was shaped in a quarter of a circle with a semidiameter of 50 mm.
  • a resin was discharged from a slit formed on the inlet of the curved die, in the forwarding direction of the running filaments, to thereby coat the filaments with the resin.
  • the filaments under a tension were run over the curved surface of the die, to have a shearing resistance so as to be impregnated with the resin.
  • Fig. 1 shows an example of this resin-impregnating system with the die.
  • the resin an ethylene-vinyl alcohol copolymer "EVAL (R)" (105B) manufactured by KURARAY CO., LTD. was used.
  • the die used had an inlet angle of 30°, a nozzle with a diameter of 0.6 mm ⁇ , and a parallel portion with a length of 0.5 mm.
  • the durability of a spun yarn which was not subjected to a twisting process was evaluated.
  • the spun yarn wound onto a resinous bobbin was stored in a container conditioned constantly at a high temperature and a high humidity. After that, the sample was taken out and then subjected to a tensile test at a room temperature. The resultant tensile strength was divided by a tensile strength of a spun yarn which was not subjected to the above storage test, and the resultant quotient was multiplied by 100 to obtain a strength retention.
  • Humidic Chamber 1G43M manufactured by Yamato Kagakusha was used for the storage test under the atmosphere of high temperature and high humidity, as well as in the evaluation of the filaments before cutting.
  • the storage test was continued for 240 hours in the above air-conditioned container which was perfectly shielded from light and kept constant at 80°C and 80%RH.
  • the tensile strength of the spun yarn with a length of 200 mm was measured according to the procedure of JIS-L1095, with a tensile tester (AG-50KNG manufactured by SHIMADZU CORPORATION).
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant polybenzazole filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,600 ppm, and that of sodium was 3,600 ppm; and the molar ratio of Na/P was 1.05.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 86%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 89%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,220 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,660 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,850 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.29 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 82%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.3 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 84%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,600 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 120 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,500 ppm, and that of sodium was 2,400 ppm; and the molar ratio of Na/P was 0.72.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 83%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 85%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,250 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,660 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 80%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 134 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,890 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 80%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 14.8 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 81%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,580 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 80%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,400 ppm, and that of sodium was 3,600 ppm; and the molar ratio of Na/P was 1.10.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 88%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 91%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,250 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 87%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,670 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,800 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 87%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.8 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 85%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,620 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 3 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,700 ppm, and that of sodium was 5,400 ppm; and the molar ratio of Na/P was 1.55.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 86%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 87%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,190 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,660 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,700 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 83%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.1 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 84%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,550 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,500 ppm, and that of sodium was 4,000 ppm; and the molar ratio of Na/P was 1.20.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 81%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 83%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,300 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,740 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 133 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,920 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 80%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.29 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 79%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 14.5 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 80%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 133 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,690 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 79%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,400 ppm, and that of sodium was 3,400 ppm; and the molar ratio of Na/P was 1.04.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 87%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 85%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,010 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 87%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,590 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 138 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,610 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.31 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 85%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.5 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 85%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 138 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,280 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • a dispersion obtained by adding terephthalic acid (5.6 g) and copper phthalocyanine (19.5 g) in 122% polyphosphoric acid (74.4 g) was added, and the mixture was allowed to react at 170°C for 5 hours and at 200°C for 10 hours to obtain poly(p-phenylenebenzobisoxazole) dope having an intrinsic viscosity of 29 dL/g at 30°C, measured using a methanesulfonic acid solution.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 120 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,600 ppm, and that of sodium was 2,400 ppm; and the molar ratio of Na/P was 0.70.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 84%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 86%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,240 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,690 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,820 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.29 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 81%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.0 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 83%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,500 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 80%.
  • a dispersion obtained by adding terephthalic acid (5.6 g) and copper phthalocyanine (19.5 g) in 122% polyphosphoric acid (74.4 g) was added, and the mixture was allowed to react at 170°C for 5 hours and at 200°C for 10 hours to obtain poly(p-phenylenebenzobisoxazole) dope having an intrinsic viscosity of 29 dL/g at 30°C, measured using a methanesulfonic acid solution.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,900 ppm, and that of sodium was 4,200 ppm; and the molar ratio of Na/P was 1.15.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 89%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 91%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,210 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 88%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,660 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,780 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 89%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 16.0 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 86%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,480 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • a dispersion obtained by adding terephthalic acid (5.6 g) and copper phthalocyanine (19.5 g) in 122% polyphosphoric acid (74.4 g) was added, and the mixture was allowed to react at 170°C for 5 hours and at 200°C for 10 hours to obtain poly(p-phenylenebenzobisoxazole) dope having an intrinsic viscosity of 29 dL/g at 30°C, measured using a methanesulfonic acid solution.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 3 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,800 ppm, and that of sodium was 5,600 ppm; and the molar ratio of Na/P was 1.15.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 86%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 86%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,150 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,670 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,790 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 82%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.0 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 84%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,560 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • a dispersion obtained by adding terephthalic acid (5.6 g) and copper phthalocyanine (5.6 g) in 122% polyphosphoric acid (74.4 g) was added, and the mixture was allowed to react at 170°C for 5 hours and at 200°C for 10 hours to obtain poly(p-phenylenebenzobisoxazole) dope having an intrinsic viscosity of 30 dL/g at 30°C, measured using a methanesulfonic acid solution.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,500 ppm, and that of sodium was 3,800 ppm; and the molar ratio of Na/P was 1.14.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 82%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 82%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,380 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,760 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 6,040 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 81%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 78%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 14.6 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 81%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 134 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,770 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 78%.
  • a dispersion obtained by adding terephthalic acid (5.6 g) and copper phthalocyanine (41.1 g) in 122% polyphosphoric acid (74.4 g) was added, and the mixture was allowed to react at 170°C for 5 hours and at 200°C for 10 hours to obtain poly(p-phenylenebenzobisoxazole) dope having an intrinsic viscosity of 28 dL/g at 30°C, measured using a methanesulfonic acid solution.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,800 ppm, and that of sodium was 3,900 ppm; and the molar ratio of Na/P was 1.09.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 87%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 88%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,380 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,560 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 85%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 138 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,590 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 86%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.29 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 85%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.3 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 85%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 137 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,310 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,900 ppm, and that of sodium was 3,900 ppm; and the molar ratio of Na/P was 1.07.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 85%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 84%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,120 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 84%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,610 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 83%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 136 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,830 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 81%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 82%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 15.0 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 84%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 135 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,500 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 82%.
  • the resultant dope was spun to make filaments each singly having a diameter of 11.5 ⁇ m and a fineness of 1.5 denier. That is, the dope was extruded through a nozzle having 166 holes with diameters of 0.18 mm at 175°C to make the filaments, which were then dipped and solidified in a first washing bath so located as to converge the filaments at an appropriate position to make a multi-filament.
  • a quench chamber was provided in an air gap between the nozzle and the first washing bath, so that the filaments could be drawn long at an uniform temperature. The quench temperature was 65°C.
  • the filaments were washed with water until the concentration of the residual phosphorous in the polybenzazole filaments reached 5,000 ppm or less, and were then wound onto resinous bobbins without drying.
  • the take-up rate was 200 m/minute.
  • the wound filament was neutralized with a 1% aqueous NaOH solution for 10 seconds, and was then washed with water for 15 seconds, followed by drying at 80°C for 4 hours.
  • concentrations of phosphorous and sodium remaining in the resultant filaments were measured by the foregoing methods. As a result, the concentration of phosphorous was 4,400 ppm, and that of sodium was 4,000 ppm; and the molar ratio of Na/P was 1.22.
  • the durability of the filament under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention thereof was 77%.
  • polybenzazole filaments thus obtained were Z-wise twisted at a rate of 32 T/10 cm to make a Z-twisted yarn.
  • Two Z-twisted yarns obtained as above were S-wise twisted at a rate of 32 T/10 cm to make a crude cord.
  • the crude cord was subjected to a two-staged dipping treatment to make a dip cord.
  • the dipping liquid for the first stage was an aqueous dispersion of an epoxy resin, and the treating temperature was 240°C.
  • the dipping liquid for the second stage was a RFL liquid, and the treating temperature was 235°C.
  • the strength retention of the resultant dip cord under an atmosphere of high temperature and high humidity was 78%.
  • the polybenzazole filaments thus obtained were cut into staple fibers with lengths of 51 mm.
  • the resultant staple fibers were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20/1 Ne. Two such spun yarns were twisted to make a two ply yarn with a cotton yarn count of 20/2 Ne.
  • the two ply yarns thus obtained were woven to make a 2/1 twill fabric filled with 68 warp yarns/inch and 60 weft yarns/inch.
  • the tensile strength of the resultant fabric in the vertical direction was 4,270 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 72%.
  • the spun yarns with a cotton yarn count of 20/1 Ne obtained as above were knitted to make a tubular knitted fabric filled with 68 stitches/inch in the vertical direction and 29 stitches/inch in the lateral direction.
  • the tensile strength of the tubular knitted fabric in the vertical direction was 1,590 N/5 cm.
  • the durability of the tubular knitted fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 70%.
  • the polybenzazole fiber yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 60 warp yarns/inch and 60 weft yarns/inch.
  • the weight of the fabric was 134 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,780 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 73%.
  • polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn having a total fineness of 1,000 deniers.
  • the yarns thus obtained were used to make a composite material by the foregoing method for making the sample of a composite material.
  • the content of the filaments in the resultant composite material was 0.30 in terms of the volume ratio.
  • the durability of the composite material under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the composite material was 73%.
  • the staple fibers with lengths of 51 mm, cut from the polybenzazole filaments thus obtained were spun at a twist coefficient of 3.5 to make a spun yarn with a cotton yarn count of 20 Ne.
  • the tensile strength of the spun yarn was 9.3 cN/dtex.
  • the durability of the spun yarn under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the spun yarn was 75%.
  • two polybenzazole filaments thus obtained were doubled but not twisted, to make a yarn with a thickness of 555 dtex.
  • the yarns thus obtained were woven with a rapier loom to make a plain weave fabric filled with 30 warp yarns/inch and 30 weft yarns/inch.
  • the weight of the resultant fabric was 133 g/m 2 .
  • the tensile strength of the fabric in the warp yarn direction was 5,540 N/3 cm.
  • the durability of the fabric under an atmosphere of high temperature and high humidity was evaluated. As a result, the strength retention of the fabric was 71%.
  • polybenzazole fibers which can sufficiently maintain the strength thereof even when exposed to an atmosphere of high temperatures and high humidity for a long period of time after yarns made thereof have had kink bands therein. Therefore, the use of the polybenzazole fibers can enhance the practical performance in the applications where the fibers are processed to woven fabrics, knitted fabrics, braids, ropes, cords and the like, which include, for example, tension materials such as cables, tension members (electric wires, optical fibers and the like) and ropes, high shock-proof members such as bullet-proof materials, cutting-proof members such as gloves, rubber-reinforcing materials such as belts, tires, shoe soles, ropes and hoses.
  • tension materials such as cables, tension members (electric wires, optical fibers and the like) and ropes
  • high shock-proof members such as bullet-proof materials
  • cutting-proof members such as gloves
  • rubber-reinforcing materials such as belts, tires, shoe soles, ropes and hoses.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Woven Fabrics (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
EP04820271A 2003-12-11 2004-12-09 Polybenzazolfaser und sie enthaltendes erzeugnis Withdrawn EP1693489A1 (de)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
JP2003412681A JP2005171416A (ja) 2003-12-11 2003-12-11 ポリベンザゾール繊維
JP2003424649A JP2005179851A (ja) 2003-12-22 2003-12-22 ポリベンザゾール繊維からなるゴム補強用コード
JP2003424650A JP2005179852A (ja) 2003-12-22 2003-12-22 高強度繊維ロープ
JP2003424653A JP2005178249A (ja) 2003-12-22 2003-12-22 複合材料
JP2003424648A JP2005179850A (ja) 2003-12-22 2003-12-22 セールクロス
JP2003424655A JP2005179856A (ja) 2003-12-22 2003-12-22 防弾チョッキ
JP2003424652A JP2005179854A (ja) 2003-12-22 2003-12-22 防刃材
JP2003424654A JP2005179855A (ja) 2003-12-22 2003-12-22 紡績糸
JP2003424651A JP2005179853A (ja) 2003-12-22 2003-12-22 織編物
PCT/JP2004/018392 WO2005056893A1 (ja) 2003-12-11 2004-12-09 ポリベンザゾール繊維およびそれからなる物品

Publications (1)

Publication Number Publication Date
EP1693489A1 true EP1693489A1 (de) 2006-08-23

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US (1) US20070104948A1 (de)
EP (1) EP1693489A1 (de)
WO (1) WO2005056893A1 (de)

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KR101930102B1 (ko) * 2011-01-13 2018-12-17 이 아이 듀폰 디 네모아 앤드 캄파니 공중합체 섬유 및 그의 제조 방법
US9481946B2 (en) * 2011-01-13 2016-11-01 E I Du Pont De Nemours And Company Copolymer fibers and yarns and processes for making same
JP6310549B2 (ja) 2014-05-08 2018-04-11 国立研究開発法人産業技術総合研究所 ポリベンズイミダゾール炭素繊維及びその製造方法
CN110983529A (zh) * 2020-01-20 2020-04-10 山东利源纤维有限公司 一种可降解pbat-bcf纱线制造工艺

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