Abstract: A fiber made of pitch having a percent elongation of about 2 percent or greater is made by melt spinning an optically isotropic pitch to form a fiber typically in the range of about 5 to about 50 microns diameter, treating the fiber with an oxidizing atmosphere, subsequently removing a certain portion of the oxidant thereby reducing the weight of the fiber, with the optional post-treatment step of repetitively stretching in the elastic range short of breakage to increase the percent elongation.

Abstract: A pitch-based carbon fiber having a high strength is produced by (a) treating a heavy oil at a temperature of 370.degree. to 480.degree. C. and a pressure of 2 to 50 kg/cm.sup.2 ; (b) separating and removing insoluble solids from the heat-treated oil so that the insoluble solids content is not higher than 50 ppm; (c) subjecting the oil to thin film distillation at a temperature of 250.degree. to 450.degree. C., a pressure of not higher than 100 mm Hg and a film thickness of not larger than 5 mm; (d) heat-treating the resulting pitch at a temperature of 340.degree. to 450.degree. C. while passing an inert gas at atmospheric or reduced pressure to obtain an optically anisotropic pitch having a softening point of 260.degree. to 300.degree. C.

Abstract: Carbon fiber precursors from pitchy materials are processed by applying thereonto an aqueous emulsion containing a single silicone oil or a mixture of silicone oils selected from polydimethyl siloxane, phenyl modified polydimethyl siloxane and aminoalkyl modified polydimethyl siloxane and having kinetic viscosity at 25.degree. C. of 100 centistokes or less, an alkanolamine salt of aliphatic monocarboxylic acid with 8-18 carbon atoms, and one or more non-ionic surfactants selected from polyoxyethylene alkylphenylethers polyoxyethylene alkylates, polyoxyethylene alkylaminoethers, and aliphatic monocarboxylic alkanolamides such that 0.1-5 wt % by solid deposit on fiber from this aqueous emulsion apply to the pitch fibers during any of the processes from the spinning and to the oxidizing.

Abstract: A carbon/carbon composite is produced by impregnating a primary-formed product consisting essentially of carbon fibers and a carbonized or graphitized matrix with a carboneceous pitch, heat-treating the thus-impregnated primary-formed product under hot isostatic pressing and carbonizing or graphitizing the thus heat-treated primary-formed product.

Abstract: A process for biaxially orienting amorphous polymers such as polymethyl methacrylate. The process includes steps of biaxially orienting a feedstock material in a deformation zone; reducing temperature of the material in a cooling zone; and annealing the material in an annealing zone. The process and apparatus produce a biaxially oriented material having enhanced optical quality and impact strength.

Abstract: A rapid method of infusibilizing (curing) preceramic polymers comprising treatment said polymers with gaseous nitrogen dioxide. The infusibilized polymers may be pyrolyzed to temperatures in excess of about 800.degree. C. to yield ceramic materials with low oxygen content and, thus, good thermal stability. The methods are especially useful for the production of ceramic fibers and, more specifically, to the on-line production of ceramic fibers.

Abstract: Acrylonitrile precursor fibers are subjected to a flame-resisting treatment, in an oxidizing atmosphere, while being elongated at least 3%, until a density of 1.22 g/cm.sup.3 is reached. The fibers are further treated to increase density up to 1.40 g/cm.sup.3, and then heat treated while undergoing further elongation, followed by higher temperature heat treatment while under tension. The resulting fibers have excellent properties, including high strand tenacity, high strand modulus, and high density.

Abstract: An air bag restraint system for protecting vehicle occupants during a collision comprising a seamless inflatable confinement of braided fabric constructed by strands of multiple fibers which are interlocked by diagonally crossing a number of these strands alternately over and under one or more of the other strands. The seamless air bag is formed by braiding textile yarns to a mold having the shape of the desired confinement. An elastomer coating may be applied to render the braided fabric either essentially non-porous and non-permeable to air or semi-permeable to control air flow. Also, methods for manufacturing such seamless braided fabric confinements.

Abstract: A method of molding a cup-shaped article such as integral vehicle wheel rim and disc segment, wherein a plurality of sections of resin-impregnated cloth are placed over a substantially cylindrical mandrel. The cloth sections are substantially identical and have circular central portions which are stacked on the mandrel end face, and oppositely projecting wings which are draped over and are circumferentially staggered around the mandrel sidewall. The central axis of each sheet section is at an angle of 45.degree. to the warp and weft fibers of the section cloth. The sheet sections thus form a mold charge which is compression molded to form an integral vehicle wheel rim and disc segment.

Abstract: In place of mechanical complicated pressure means which apply a pressure upon binder impregnated carbon fibers when they are heated to be a compounded compact of a desired shape, thermo-resistant fibers having a negative coefficient of linear expansion and wound up directly or indirectly over the carbon fibers, are employed so that they tightly fasten the carbon fibers under a pressure on account of their contraction by heat, whereby the shaping and heating of the carbon fibers can readily be achieved and controlled.

Abstract: The present invention relates to a carbon fiber having a novel structure in which the outer circumferential part of fiber section is constituted of an optically isotropic component and its central part is constituted of an optically anisotropic component or an optically anisotropic component partially containing optically isotropic component, which the carbon fiber shows no cracks at all, as well as to a process for producing said carbon fiber.

Abstract: In a method of producing mesophase pitch based carbon fibers, including the steps of melt-spinning a mesophase pitch through a nozzle (1) having at least one pair of a counter-bore (2) and a circular capillary (3) to form a pitch fiber and subjecting the pitch fiber to an infusible treatment, a carbonization treatment, and if necessary, a graphitization treatment, to form a carbon fiber, the nozzle has a degree of asymmetry .phi. of from 0.1 to 0.9, .phi. being defined by the following equation .phi.=S.sub.A /S.sub.B, wherein S.sub.A is an area of an inscribed circle in a contour of the cross-section of the counter-bore, which circles is perpendicular to the nozzle axis and has a center on the axis of the capillary and inscribed and S.sub.B is a total area of the cross-section of the counter-bore.

Abstract: A method is proposed for the preparation of pitch-based carbon fibers having excellent mechanical properties or , in particular, a surprisingly high knot strength much higher than that of PAN-based carbon fibers. The method comprises the steps of melt-spinning of starting pitch material, infusibilization of the pitch fibers by oxidation and carbonization of the infusibilized pitch fibers in an inert atmosphere. The improvement of the inventive method consists in the infusibilization treatment of pitch fibers under controlled conditions so as to effect preferential oxidation of the surface layer to such an extent that the value m=(O.sub.1s /C.sub.1s)/(O/C) is at least 2, in which O.sub.1S /C.sub.1S is the molar ratio of the oxygen content to the carbon content in the surface layer as determined by the ESCA method and O/C is the molar ratio or the oxygen content to the carbon content for the infusibilized pitch fiber as a whole.

Abstract: The present invention relates to a process for producing a carbon fiber chopped strand which comprises preparing a pitch fiber from petroleum pitch or coal pitch, cutting the pitch fiber to a predetermined desired length, heating the cut pitch fiber at a high density accumulation in the atmosphere of an oxidative gas to infusibilize the cut pitch fiber, and then carbonizing and graphitizing the infusibilized fiber in an inert atmosphere. According to the process of the invention, no fuzz are formed on the fiber and no uneven infusibilization takes place. Further, the pitch fiber chopped strand accumulation has a high bulk density and relieve exothermic excursion naturally, and therefore neither combustion nor sticking takes place even in an oxidative atmosphere. Accordingly, the production speed can be enhanced and the cost can be lowered to a great extent.

Abstract: The invention relates to novel polysilazanes, their preparation, their further processing to ceramic material containing silicon nitride and this material itself. To prepare the polysilazanes, Si,Si'-diorganyl-N-alkyltetrachloro-disilazanes of the formula RSiCl.sub.2 -NR'-SiCl.sub.2 R are reacted with ammonia. The polysilazanes can then be pyrolyzed to ceramic material containing silicon nitride. The polysilazanes according to the invention dissolve in the customary aprotic solvents.

Abstract: Polyacrylonitrile (PAN)-based carbon fiber in the form of a filament bundle has a high Modulus and a high Tensile Strength in the Impregnated Strand Test respectively between about 42 million and 50 million psi and between about 600,000 and 900,000 psi, and Short Beam Shear Strength between about 15,000 and 19,000 psi in the Laminate Test; this PAN-based carbon fiber also has an electrolytically treated surface at 0.5 columbs per inch per approximate 12,000 filaments. The preparation of this PAN-based carbon fiber was accomplished by stretching during carbonization previously stretched and stabilized fine denier precursor while maintaining temperatures and heat up rates within certain ranges.

Abstract: Shaped refractory products, particularly in the form of hollow spheres, and a process for their formation. The process involves dispersing particles of silica or a metal oxide, e.g. Al.sub.2 O.sub.3, in an organic polymer, shaping the dispersion into a desired shape, heating the shaped dispersion in a non-oxidizing atmosphere to carbonize the polymer, and heating the carbonized product at high temperature in a non-oxidizing atmosphere containing nitrogen so that some of the oxide is converted to the corresponding nitride and the particles of unreacted oxide sinter together. The ratio of oxide to carbon should be high so that some but not all of the oxide is converted to the nitride and, preferably, only a relatively small amount should be converted. The resulting refractory material is strong and can be used for a variety of uses, e.g. catalyst supports, packing materials and insulating materials.

Abstract: An improved process for producing an anisotropic pitch product suitable for carbon fiber manufacture. A carbonaceous feedstock is heated at elevated temperature while passing a reactive sparging gas through the feedstock. The sparging gas is an oxidative gas such as a gaseous mixture containing a major proportion of inert gas and from about 0.1 to 2% by volume of oxygen. The process produces an anisotropic pitch having from 50 to 100% by volume mesophase which is suitable for producing good quality carbon fibers.

Abstract: Preceramic fibers are produced by dissolving a solid organosilicon preceramic polymer in a solvent to form a spinning solution containing at least seventy percent polymer solids, dry spinning and extracting solvent in the presence of a non-oxidizing gas at a temperature and pressure sufficient to vaporize solvent from the fiber, and at least one curing agent being added to the non-oxidizing gas or spinning solution, or both, to induce on-line curing of the fiber or to aid in subsequent curing of the fiber or both. The preceramic fibers are thereafter pyrolyzed to ceramic form.

Abstract: There are provided improved processes for the manufacture of enriched pitches, carbon fiber precursors, carbon fibers, and graphite fibers. The improvement comprises employing an elevated wiped-film evaporator in a wiped-film evaporator system comprising the wiped-film evaporator and a means for recovering enriched pitch, such as a positive displacement pump, to form an enriched pitch from catalytic pitch and regulating the operating conditions of the wiped-film evaporator system to provide the desired enriched pitch. The wiped-film evaporator is located a specific distance above the means for recovering enriched pitch. The vertical distance between the outlet of the wiped-film evaporator and the inlet of the means for recovering enriched pitch is within the range of about 10 feet to about 40 feet, preferably about 20 feet to about 40 feet.

Abstract: An elastomer-coated fabric for use as a confinement. The confinement is formed by conforming a fabric to a mold having the shape of the desired confinement, and subsequently applying a layer of elastomer to the fabric. A curing operation then cures the elastomer such that the elastomer-coated fabric retains the shape of the mold. Advantageously, the curing operation also relaxes and heat sets the fabric in order to permit a controlled amount of further stretch, even if the fabric was stretched a maximum amount when it was conformed to the mold.

Abstract: A process of making carbon-bonded refractory shapes by preparing a mix of refractory materials, pitch or tar and a binder resin, molding the mix into shapes and hardening the shapes. A starting mix is used which, based on the added quantity by weight of pitch or tar, contains 1 to 10 weight % of hollow fibers. The refractory shapes have the advantage that they exhibit less cracking, and hardly any, or even no, breaking occurs during their fabrication.

Abstract: Carbon fibers having balanced properties comprising an ultra-high modulus greater than 100 Mpsi and a high tensile strength of greater than 500 kpsi. The carbon fibers are derived from a solvent fractionated pitch having a mesophase content of greater than 90% by weight and a quinoline insolubles content of less than 1% by weight. A crude pitch feed is sequentially heat soaked, solvent fractionated, and extruded to form as-spun fibers. The latter are stabilized or infusibilized and then carbonized by multistage heat treatments involving separate precarbonization, carbonization, and graphitization steps with an intermediate cooling step.

Abstract: A process for preparing laminates of polyvinyl fluoride and at least one other fluoropolymer that are free from adhesive at the interface by dispersion coating a first film to form a second film and curing the second film at a temperature below the melting point of the first film.

Abstract: This invention provides a method for infusibilization of pitch fibers for production of carbon fibers which comprises putting pitch fibers prepared by melt spinning from a spinning pitch in containers, introducing in succession the containers containing the pitch fibers into an infusibilizing furnace divided into a plurality of sections and passing the containers therethrough from inlet to outlet wherein the containers containing the pitch fibers are intermittently moved through the infusiblizing furnace to retain each of the containers in respective sections for a given period of time, during which temperature of respective sections is independently raised from minimum controlled temperature to maximum controlled temperature and thereafter is lowered to the minimum controlled temperature and then the container is moved.

Abstract: The invention relates to a method for forming twin-wall polycarbonate sheets into desired arcuate forms to be used, for example, as awnings. The method is distinguished from known forming techniques which are generally not effective in forming the polycarbonate sheets hereinafter described.The method generally includes preheating a portion of the polycarbonate sheet within a heating chamber, engaging the sheet with the mould which is pivotally mounted to the frame of an apparatus within the heating chamber, frictionally restraining the movement of the sheet with respect to the frame at a position spaced from the mould, and outside the heating chamber, and pivoting the mould so as to form the sheet.The present invention generally overcomes the difficulties in forming twin-walled polycarbonate sheets thereby allowing this material to be used in place of other conventional awning materials such as fibreglass and corrugated iron.

Abstract: A high strength, ultra high modulus carbon fiber is characterized by the presence of the (112) cross-lattice line and the resolution of the diffraction band into two distinct lines (100) and (101), which indicate the three-dimensional order of the crystallite of the fiber. It has an interlayer spacing (d.sub.002) of 3.371 to 3.40 .ANG.; a stack height (Lc.sub.002) of 150 to 500 .ANG.; and a layer size (La.sub.110) of 150 to 800 .ANG..

Abstract: In a system of packaging of foodstuffs in containers of rectangular horizontal section, each open-topped container is sterilized, filled, and closed with a sterilized closure. The closure is of a laminate including a thermoplastics layer of sufficient thickness to fill an internal discontinuity of the container mouth during heat-sealing of the closure to the container. In making the closure, a portion of laminate is partially severed to form a flap and the laminate is clamped around the flap and drawn to form a shallow dish, to the inside of the base of which is heat-sealed a diaphragm including a pull tab. The thermoplastics layer is on a reflective metal layer and incorporates infrared-absorbing particles and infrared-reflective particles.

Abstract: A process for producing a carbon fiber by subjecting a pitch fiber, obtained by melt spinning a carbonaceous mesophase pitch, to stabilization, followed by a carbonization or graphitization treatment, wherein the stabilization is carried out under an oxidative atmosphere containing 0.1% to 40% by volume of NO.sub.2 and 4% to 40% by volume of H.sub.2 O at a temperature of from 100.degree. C. to 400.degree. C.

Abstract: Three dimensional woven fabrics containing bent parts of a small radius of curvature which bent parts comprise easily graphitized pitch-derived carbon fibers obtained by thermosetting treatment and light carbonization treatment carried out after melt-spinning of high softening point pitch and having a tensile strength of 15 250 Kgf/mm.sup.2, an elongation of 0.5-8.0% and modulus of elasticity of 400-40,000 Kgf/mm.sup.2 and a capability of increasing both of their tensile strength and modulus of elasticity to 1.1 times or greater than the above-mentioned values by additional heat treatment carried out under a relaxed state to have a tensile strength of 150 Kgf/mm.sup.2 or greater and a modulus of elasticity of 40,000 Kgf/mm.sup.2 or greater. They are superior in abrasion resistance, flexion-resisting property and scratch-resisting property and useful as one component of fiber composite materials in reinforcing plastics, metals, cements, ceramics, carbon materials, etc.

Abstract: A three-dimensionally shaped aromatic imide polymer sheet article is produced by a method comprising the steps of shaping an aromatic imide polymer sheet having a second order transition temperature of 250.degree. C. to 400.degree. C. and an ultimate elongation of 120% or more at 100.degree. C., by press-stretching at least a portion of the sheet at a temperature of 100.degree. C. or more, but not exceeding a temperature of 100.degree. C. higher than the second order transition temperature of the sheet, into a desired three-dimensional convex or concave form protruding from the sheet, heat-setting the resultant shaped sheet article in its shaped form at a temperature equal to or higher than the second order transition temperature of the sheet, and then cooling the heat-set sheet article to a desired low temperature.

Abstract: A novel isotropically reinforced microcomposite is described. An entirely fluid-phase method has been devised for producing the net-shape filamentary structures. The process depends for its success on the ability to generate in situ, within a shaped mold, a three-dimensional random weave of carbon filaments by catalytic decomposition of a hydrocarbon feed. Almost any desired filament filler matrix combination can be produced by utilizing chemical vapor deposition to modify the surface and bulk properties of the filamentary structure. Infiltration of filler matrix materials can be achieved by adaptation of existing materials technologies.

Abstract: In an installation for deep-drawing and back-foaming of upholstery covers, the deep-drawing molds are disposed on a round table. Besides the round table for the deep-drawing molds, a stationary stretch piston station is provided, serving all deep-drawing molds on the round table passing the stretch piston station.

Abstract: Crystallizable mainly amorphous thermoplastic material is crystallized at a temperature exceeding the glass transition temperature of the material (13) by subjecting the material at the elevated temperature to compressive forces. The material thickness as a rule is reduced by at least 20%, preferably by at least 40%. To achieve this a plunger (20) and a mould (30) are moved to a minimum distance at which the thermoplastic material (13) located between the plunger and the mould part is subjected to compressive forces. The plunger and/or the mould part are provided with elements (29, 39) for the setting and maintaining of a temperature specified in advance of the surfaces (23, 33) by which the plunger and the mould part respectively abut against the thermoplastic material.

Abstract: A method of manufacture of pitch-based carbon fiber by infusibilization of pitch fiber followed by carbonization, comprising doping the pitch fiber with at least 0.05 percent by weight of iodine, heating under an oxidizing atmosphere for infusibilization, and then heating under an inert atmosphere for carbonization, whereby it is carbonized or graphitized.

Abstract: A process is described for producing filter elements which contain a cross-wound yarn as the filter material, wherein twisted yarn of fine individual fibers is roughened to enhance its filtering action. The yarn may be heat-resistant and the filter element may be used as a soot filter in the exhaust gas stream of an internal combustion engine. Before the yarn is wound up, fiber tufts are broken up by pulling the yarn under tension over a moving roughening surface, the direction of movement of the roughening surface differing by an angle alpha from the direction of movement of the yarn in the area of contact between the yarn and the roughening surface, and the angle alpha being selected in relation to the twist of the yarn, particularly so that the threads of the yarn in contact with the roughening surface are oriented transversely to the direction of movement of the roughening surface. The process produces a roughened yarn which provides the required high filter performance for a soot filter.

Abstract: A device for gripping and pulling a length of thermoplastic sheet softened to be moldingly formed at the front and rear edges, which are otherwise inevitably made to be concave, so as to hold edges substantially straight. The device uses at least two pairs of lower and upper gripping members arranged to be vertically movable so as to grip the above front and rear edges. Two pairs of pull levers each cooperating with one of the pair of lower and upper gripping members operate so as to grip the front and rear edges in advance of the gripping by the gripping members and pull to straighten the concaved edges which are then gripped by the gripping members.

Abstract: A process for producing an acrylic carbon fiber comprising the steps of applying an oiling agent comprising as its indispensable component a neopentyl alcohol derivative represented by the following general formula (I) to acrylic fiber, heating the lubricated acrylic fiber in an oxidizing atmosphere to convert the same into oxidized fiber, and heating the oxidized fiber in an inert atmosphere at a higher temperature to carbonize the same: ##STR1## The process can eliminate the defects of acrylic fiber precursor and provide a carbon fiber having excellent mechanical strength characteristics.

Abstract: Dense highly pure fibers of silicon carbide are made by incorporating silicon carbide particles into a polymeric silicon carbide precursor, spinning and sintering.

Abstract: An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production.

Abstract: An acrylic multifilamentary material possessing an internal structure which is well suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of C.sub.1 to C.sub.2 nitroalkane and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. During the melt extrusion a C.sub.1 to C.sub.4 monohydroxy alkanol preferably also is present in the substantially homogenous admixture. The fibrous material which is capable of readily undergoing drawing next is passed through a heat treatment zone wherein the evolution of residual nitroalkane, monohydroxy alkanol and water takes place.

Abstract: A process for forming a plastic article, such as a container, involves heating at least one or more layers individually to temperatures below the melting point, immediately stacking two or more layers while retaining the peripheral portion of the layers and immediately forming the stacked layers into a plastic article which is then allowed to cool. Alternatively after stacking the layers, the stacked layers are immediately forged into a preform in a heated and lubricated mold and immediately thermoformed into a plastic article, which is then allowed to cool. The layers may be diverse (i.e. material, shape, molecular weight, additives, etc.) or similar and stacked so as to provide a layered angular orientation.

Abstract: In a method of manufacturing carbon fiber with less uniformity of physical strength in the longitudinal direction, an oil additive in a volatile medium is applied to an organic fiber after it is removed from a container and while the volatile medium has not completely evaporated from the fiber, and before the fiber is fed to a flameproofing furnace.

Abstract: Titanium-containing preceramic fibers are provided with a high loading of titanium by impregnating a polymeric fiber with a liquid comprising a titanium alkoxide where the alkoxide contains at least 2 carbon atoms and precipitating the titanium alkoxide in the fiber as titanium dioxide. Useful titanium alkoxides include titanium tetraethoxide, titanium tetrabutoxide and titanium isopropoxide.

Abstract: Disclosed herein is an improved pitch for making readily stabilizable, substantially nonmesophasic carbon fibers. The pitch has a softening point of about 250.degree. C. (480.degree. F.) or above and is produced from an unoxidized thermal petroleum pitch by selectively reducing or eliminating a portion of the low molecular weight materials in a very short period of time so that the tendency to produce mesophase pitch is eliminated or reduced and so that the chemical integrity of the components of the higher molecular weight fractions is preserved as much as possible. Also disclosed is a method of producing carbon fibers therefrom and rovings or mats from such fibers.

Abstract: A hollow body (e.g. a container) as well as a method and an apparatus for its manufacture in which an axially directed wall of the body primarily is made of oriented and/or crystallized plastics material. A tubular preform (10d) is fixed in a circumferential region (13d) in the vicinity of the mouth edge (14d) of the preform between mechanical forming devices (30,40), after which the devices, during continued clamping of the circumferential region, are displaced in the axial direction of the preform relative to a mandrel (50). Thus, the mandrel is displaced into the preform during simultaneous expansion thereof and the material is oriented and/or crystallized. In a preferred embodiment there is made a certain compensation of the stretching forces, which arise in the material when inserting the mandrel, by applying a force to the bottom of the preform by a bottom support (75).

Abstract: A carbon fiber of high strength is disclosed, each filament of which is substantially circular in its cross-section but which has circumferential ruggedness which extends in parallel to an axis of the filament to form pleats. The ruggedness has a depth of more than 0.1 .mu.m.The carbon fiber is prepared by extruding a spinning solution of an aqueous polyacrylonitrile/pure zinc chloride solution of a specified polymer content into a coagulating bath at a specified draft ratio, followed by washing, drying and stretching at a total stretching ratio of 10-20 folds to form a precursor which is then subjected to conventional stabilizing and carbonizing steps.

Abstract: A carbon fiber having a cross-sectional structure of regular mesh form orientation as observed by a polarizing microscope is produced by a method comprising melt spinning pitch material through spinning nozzles, followed by infusible treatment and carbonization, wherein a mesh filter layer is provided at an upstream portion of each nozzle, and the pitch material is passed first through the mesh filter layer and then through the nozzle for spinning.

Abstract: An ultrahigh strength carbon fiber having a surface layer having a crystalline completeness which is substantially the same as or higher than that of the central region of the fiber, and a functional group amount ratio .[.(O.sub.ls /C.sub.ls).]. .Iadd.(O.sub.1s /C.sub.1s) .Iaddend.of 0.1 to 0.4 as detected in the fiber surface by X-ray photoelectron spectroscopy, the surface layer preferably having an ultrathin outermost layer having a lower crystalline completeness than the central region of the fiber.

Abstract: A process for producing a graphite fiber is disclosed, which is characterized by using, as a starting material, an optically anisotropic pitch prepared from a compound having a specific chemical structure as represented by formula (I) shown in the specification. The resulting graphite fiber shows a highly developed graphite structure and has excellent electrical conductivity.