Toyo Boseki Kabushiki Kaisha

The Dow Chemical Company

Yoshihiko Teramoto

Timothy L Faley

Michael E Mills

Tooru Kitagawa

Masaru Nakagawa

George J Quarderer, Jr

Chieh-Chun Chau

Myrna Serrano

Ashish Sen

Seiji Watanuki

Michio Ishitobi

Yoshikazu Tanaka

Steven Rosenberg

Godo Sakamoto

Kazuyuki Yabuki

Kazuo Kurita

Hiroki Murase

Syoji Oda

Kiyoshi Hotta

Shoichi Uemura

Timothy J Rehg

Yusuke Shimizu

Kohei Kiriyama

Ravi B Shanker

Douglas E Turek

To provide fibers which retain the excellent heat resistance and flame retardancy inherent in polybenzazole fibers and pyridobisimidazole fibers, have improved post-processability and neither necessitate considerable change in production process conditions nor require a high-temperature and long-time heating treatment. With respect to the polybenzazole fiber and pyridobisimidazole fiber, in an electron diffraction diagram of a surface layer part (from the surface to 1 &#x3bc;m) of the fibers, the fibers containing a crystal present in a state satisfying that S2/S1 is in a prescribed range, wherein S1 is a diffraction peak area derived from a crystal (200) plane and S2 is a diffraction peak area derived from a plurality of other crystal planes along an equatorial direction profile.

Polybenzazole fiber and pyridobisimidazole fiber

A method of preparing a precursor for a composite having wet strength of 2 to 50 kgf/mmand a mean surface void diameter of 0.01 to 2 &#x3bc;m by molding a solution of a rigid polymer having a concentration of 1 to 1.3 times the optical anisotropy lower limit solution concentration C2, thereafter rendering the solution non-flowable by absorbing a coagulant under a condition causing no solvent extraction and thereafter extracting the solvent, and a method of preparing a molecular composite having a mean thickness of 2 to 200 &#x3bc;m by impregnating this precursor for a composite with a solution of a polymer or reactive molecules.

Method of preparing composite from rigid polymer solution and composite film

A high strength polyethylene filament having tenacity of at least 15 cN/dTex, which comprises a polyethylene having a weight-average molecular weight of 300,000 or less and a ratio of a weight-average molecular weight to a number-average molecular weight (Mw/Mn) of 4.0 or less as determined in a state of the filament, and containing 0.01 to 3.0 branched chains per 1,000 backbone carbon atoms. When cut fibers are obtained by cutting the polyethylene filament, a rate of dispersion-defective fibers is 2.0% or less.

High-strength polyethylene fiber

The present invention provides a method for producing a formed article from a dope comprising a polyphosphoric acid solvent and a polymer soluble in polyphosphoric acid, which includes using a production apparatus containing an apparatus for stirring and uniformly dispersing or homogenizing a dope and a pump apparatus for delivering the uniformly dispersed or homogeneous dope, wherein at least one of the apparatus and the pump apparatus has a part that comes into contact with the dope. According to the present invention, maintenance frequency of production facility due to the corrosion and elution of metal in a recovered solvent can be reduced, which in turn decreases the production cost.

Method for producing formed article from polyphosphoric acid solution

A polybenzazole fiber characterized by having an elastic modulus of not less than 1350 g/d and requiring not longer than 10 minutes to reduce its water content from 2.0% to 1.5%, when determined using a thermogravimetric analyzer at 110.degree. C. after moisture absorption of not less than 2.0% of a fiber, and a method for manufacturing such a polybenzazole fiber, comprising extruding a spinning dope comprising polybenzazole and a polyphosphoric acid from a spinneret to give a dope filament, and cooling the dope filament to not more than 50.degree. C., followed by coagulation and washing. According to the method of the present invention, a polybenzazole fiber showing less decrease in strength by rapid heating can be provided.

Polybenzazole fiber and method for production thereof

The present invention provides processes for producing polybenzazole fibers where a spinning dope containing a polybenzazole polymer in an acid solvent is extruded through a spinning nozzle, followed by coagulation in a coagulating medium and washing with a fluid capable of dissolving the acid solvent; thereafter, in one process, the fiber obtained by the coagulation under specific conditions and the subsequent washing is dried in a heating zone with at least 80% part based on the total length thereof being set at a temperature of 240.degree. C. or higher, and in the other process, the fiber obtained by the coagulation under the conventional conditions and the subsequent washing is neutralized with a basic solution, followed by washing with a fluid capable of dissolving the basic solution, and then dried at a specific temperature set depending upon the residual moisture content in the fiber. The present invention further provides a polybenzazole intermediate predried fiber having a residual moisture content of about 25% and exhibiting a single peak for liquid freezing in the fiber over a temperature range of from 20.degree. to -70.degree. C. when measured by differential scanning calorimetry (DSC).

Processes for producing polybenzazole fibers

In a process for preparing polybenzoxazole or polybenzothiazole filaments by extruding a polybenzoxazole or polybenzothiazole dope, drawing the dope filament across an air gap, and coagulating the dope filament; the number of filament breaks can be reduced by placing a stress isolation device after extruding but before coagulating the filament.

Method for preparing polybenzoxazole or polybenzothiazole fibers

Described is a continuous process for removing polyphosphoric acid from a polybenzazole dope filament, which comprises: (a) contacting the dope filament with water or a mixture of water and polyphosphoric acid under conditions sufficient to reduce the phosphorous content of the filament to less than about 10,000 ppm by weight; and then (b) contacting the dope filament with an aqueous solution of an inorganic base under conditions sufficient to convert at least about 50 percent of the polyphosphoric acid groups present in the filament to a salt of the base and the acid. It has been discovered that contacting the dope filament with a solution of a base after washing the filament to remove most of the residual phosphorous advantageously leads to an improvement in the initial tensile strength of the filament, as well as improved retention of tensile strength and/or molecular weight (of the polybenzazole polymer) following exposure to light and/or high temperatures.

Process for the preparation of polybenzazole filaments and fibers

Polybenzoxazole or polybenzothiazole polymer dopes are spun through a spinneret having an orifice density of more than 0.25 per cm.sup.2 to form filaments. The filaments formed then pass through an air gap which has a gas flowing into it at a temperature of between about 5.degree. C. to about 100.degree. C. and at a flow rate between about 0.1 meters/second and about 2.0 meters/second. The filaments cool in the air gap and are then coagulated. During or after coagulation the filaments are combined into one or more fibers. By this method of controlling the temperature in the air gap it is possible to stably spin polybenzoxazole or polybenzothiazole fibers at relatively high final line speeds.

Method for stable rapid spinning of a polybenzoxazole or

Polybenzazole polymer dopes are spun into fibers at high speed by passing through a spinneret with proper selection of hole geometry, followed by spin-drawing to a spin-draw ratio of at least 20, washing, taking up and drying. The take up speed is at least about 150 meters per minute, and the fibers are spun in at least 10 km lengths without a break.

Method for spinning a polybenzazole fiber

Polybenzazole polymer dopes are spun through a spinneret having more than 2 per cm.sup.2, of orifices in relatively close proximity. The dope filaments formed, then pass through an air gap which has a temperature of 50.degree. to 100.degree. C. and a gas flow sufficient to uniformly reduce the temperature of the dope filaments. The filaments cool in the air gap and are then coagulated.

Method for rapid spinning of a polybenzazole fiber

A process for producing polyester fibers having excellent tensile properties, particularly suitable as reinforcement material for tires, belts, etc., involves melt-spinning an ethylene terephthalate polyester to form highly oriented low crystalline polyester filaments which, at the state of being taken-up and prior to being drawn, having birefringence (.DELTA.n) and specific gravity (SG) within the below indicated ranges (a) and (b), and then, without winding-up, subjecting the said filaments immediately to drawing and heat treatment between the first godet rolls and second godet rolls under a draw ratio (DR) defined by the following formulas:

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Ohtsu, Japan

Yoshihiko Teramoto