Abstract: There are here disclosed carbon fibers for reinforcement of cement which are obtained by applying, onto the surfaces of carbon fibers, esters of oleic acid and aliphatic monovalent alcohols, esters of oleyl alcohol and monovalent fatty acids, polyoxyalkylene bisphenol ethers or polyether esters as sizing agents, and a cement composite material having a bending strength of 300 kgf/cm.sup.2 or more which contains cut carbon fibers having a fiber length of 10 to 50 mm at a mixing volume ratio of the cut carbon fibers to the cement matrix in the range of 1 to 5%. According to the present invention, there are provided the carbon fibers for reinforcement of cement which have excellent adhesive properties to the cement, good process passage properties through a direct spray gun and good bundling properties and which are suitable for a direct spray method, and the cement composite material using the carbon fibers and having high bending strength.

Abstract: A negative electrode for use in a secondary battery which comprises milled graphite fibers derived from mesophase pitch each having circumferential, upper end and lower end faces, the milled graphite fibers each being composed of graphite layers having therebetween voids as inlets and outlets for lithium ions, all of the circumferential, upper end and lower end faces having openings of the voids between the graphite layers, which serve as inlets or outlets for lithium ions. This negative electrode for use in a secondary battery can be utilized to provide a lithium secondary battery of nonaqueous electrolyte which has large charge and discharge capacities and which permits setting the current density at charge or discharge high.

Abstract: A negative electrode material for use in lithium-ion secondary batteries, comprising milled pitch-based graphite fibers (A) obtained by graphitization at 2400.degree. C. or higher and milled pitch-based carbon fibers (B) obtained by carbonization at 550.degree. to 1300.degree. C. In this negative electrode material, it is preferred that both the milled pitch-based graphite fibers (A) and the milled pitch-based carbon fibers (B) have an average particle size of 10 to 30 .mu.m, that the ratio of milled pitch-based carbon and graphite fibers having a particle size of 5 .mu.m or less to all the milled pitch-based carbon and graphite fibers is not greater than 10% by weight and that the milled pitch-based graphite fibers (A) and the milled pitch-based carbon fibers (B) are blended at a weight ratio (A/B) of 95/5 to 40/60.

Abstract: There are here disclosed carbon fibers for reinforcement of cement which are obtained by applying, onto the surfaces of carbon fibers, esters of oleic acid and aliphatic monovalent alcohols, esters of oleyl alcohol and monovalent fatty acids, polyoxyalkylene bisphenol ethers or polyether esters as sizing agents, and a cement composite material having a bending strength of 300 kgf/cm.sup.2 or more which contains cut carbon fibers having a fiber length of 10 to 50 mm at a mixing volume ratio of the cut carbon fibers to the cement matrix in the range of 1 to 5%. According to the present invention, there are provided the carbon fibers for reinforcement of cement which have excellent adhesive properties to the cement, good process passage properties through a direct spray gun and good bundling properties and which are suitable for a direct spray method, and the cement composite material using the carbon fibers and having high bending strength.

Abstract: A fiber reinforced plastic pipe comprising a cylindrical inner layer formed by winding a prepreg sheet containing a thermosetting resin as a matrix and an outer layer formed by winding a thermoplastic resin sheet or tape around the inner layer, said inner and outer layers being heat cured and thermocompression bonded in one united body; and a process for manufacturing the fiber reinforced plastic pipe. When the fiber reinforced plastic pipe is manufactured, the thermosetting resin is used for forming the inner layer and the thermoplastic resin is used for forming the outer layer. Moreover, a metal coat can be firmly bonded to the surface of the outer layer. Hence, a fiber reinforced plastic pipe prominently improved in impact resistance, abrasion resistance and lightweight properties can be provided.

Abstract: A process for providing activated carbon fibers consisting of optically anisotropic components and optically isotropic components by spinning a pitch into fibers, and infusibilizing the resulting fibers, followed by an activation treatment. The pitch for spinning is prepared by melt mixing together (A) 100 parts by weight of an optically isotropic pitch having a softening point of 230.degree.-300.degree. C. obtained by heat treatment of a pitch while blowing an oxygen containing gas into the pitch, and (B) 10-50 parts by weight of an optically isotropic pitch having a softening point of 200.degree.-270.degree. C. obtained by polymerization of naphthalene in the presence of a Lewis acid catalyst. The optically isotropic pitch (B) is further characterized as having the property of being converted into an optically anisotropic pitch by the stress occurring at the time of spinning.

Abstract: Pitch-based carbon fibers on which silicone based spin finish oils remain in the amount of 0.1-2.0% by weight of said fibers and having a stack height of the crystallites L.sub.C (002) of 16-28.ANG., an interlayer spacing distance d.sub.002 of 3.46-3.49.ANG., a tensile strength of 5-50 Kgf/mm.sup.2 and an elongation of 0.3-8.0% are provided. The said pitch-based carbon fibers show good cohesiveness and lubricity of fiber bundles and superior in adaptation to various kinds of processes.

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: High strength, high modulus carbon fibers derived from high mesophase content pitch, having a plurality of sheets formed of planes of hexagonal carbon networks oriented, in the direction of the fiber axis and having a cross-sectional arrangement which does not carbonize to a graphitic structure are characterized by electron and X-ray diffraction pattern wherein the (10) band is not resolved into (100) and (101) lines, by an interlayer spacing greater than 3.38 angstrom and by negative magnetic resistivity when composed to graphitized fibers.

Abstract: A method for producing mesophase pitch based carbon fibers which enables to produce high strength high modulus carbon fibers at a relatively low temperature with stabilized production manner. This method comprises carbonizing infusibilized fibers, in an inert atmosphere under no tension state or a tension of 1 mg/denier or less in the first stage to give a specified interlayer spacing and a crystallite thickness and then carbonizing under a tension of 50-300 mg/denier at a temperature of 2600.degree. C. or more in the second stage.

Abstract: A method for producing high strength, high modulus carbon fibers having a modulus of elasticity of 75 tonf/mm.sup.2 or more and a tensile strength of 250 kgf/mm.sup.2 or more is provided. This method comprises graphitizing mesophase-pitch-based carbon fibers at a temperature of 2600.degree. C. or more for several seconds or for several minutes while stretching said fibers with a stretching ratio which satisifies specified relations.