Abstract: Milled carbon fibers are provided which have a fiber cut surface and a fiber axis intersecting with each other at cross angles, the smaller one thereof being at least 65° on the average. The milled carbon fibers may have a specific surface area as measured by the BET method of 0.2 to 10 m2/g. The milled carbon fibers may be obtained by a process comprising melt spinning of mesophase pitch, infusibilization, milling of the infusibilized pitch fibers as obtained or after a primary heat treatment at low temperatures in an inert gas and a high-temperature heat treatment in an inert gas.

Abstract: Milled carbon fibers are provided which have a fiber cut surface and a fiber axis intersecting with each other at cross angles, the smaller one thereof being at least 65° on the average. The milled carbon fibers may have a specific surface area as measured by the BET method of 0.2 to 10 m2/g. The milled carbon fibers may be obtained by a process comprising melt spinning of mesophase pitch, infusibilization, milling of the infusibilized pitch fibers as obtained or after a primary heat treatment at low temperatures in an inert gas and a high-temperature heat treatment in an inert gas.

Abstract: There are disclosed graphite materials for a negative electrode used in a lithium secondary battery which graphite materials have an average specific surface area of 1.5 m2/gram to 5 m2/gram and comprise (A) milled graphite fibers which are produced by milling and graphitizing mesophase pitch-based carbon fibers, and which have an interplanar spacing of the graphite layer (d002) of at most 0.337 nm and a specific surface area of 0.8 m2/gram to 1.3 m2/gram; and (B) graphite materials which have an interplanar spacing of the graphite layer (d002) of at most 0.336 nm, a degree of graphitization (P101/P100) of at least 2.0 and a specific surface area of 2 m2/gram to 15 m2/gram, wherein the components (A) and (B) are mixed at a ratio (A)/(B) by weight of 90/10 to 50/50.

Abstract: Mesophase pitch-based activated carbon fibers which are obtained by milling infusibilized mesophase pitch fibers, as they are or after carbonizing at a temperature of 350 to 1,000.degree. C., to an average particle diameter of 5 to 50 .mu.m and then activating in the presence of an alkali metal compound. The activated carbon fibers have a pore distribution suitable for forming a electric double layer and is excellent as the material for an electrode of an electric double layer capacitor. The electric double layer capacitor having the electrode using the activated carbon fiber exhibits high discharge capacity.

Abstract: A process for producing graphite materials for a negative electrode used in a lithium secondary battery which process includes the steps of packing carbon materials having an average particle diameter of 5 to 50 .mu.m in a plurality of boxes, placing the boxes in a graphitization furnace, subjecting the graphite materials to graphitization treatment, and thereafter subjecting the resultant graphite materials to uniformization treatment by mixing and agitation. The above process is capable of decreasing the influence on the qualitative variation of graphite materials ascribed to packing operation into boxes for graphitization, to the position of the materials in a graphitization furnace, and to bubbling phenomenon or the like through graphitization treatment, and is also capable of stabilizing the qualities of the resulting graphite materials and increasing the productivity.

Abstract: A surface graphitized carbon material comprising a graphitic surface and a carbonaceous internal part. This surface graphitized carbon material can be produced by contacting a carbon material with a metal having catalytically graphitizing activity or a compound thereof to thereby cause the metal or compound thereof to be present in a surface of the carbon material and heating the carbon material at 300 to 1500.degree. C. in an inert atmosphere.

Abstract: A mesophase pitch-based carbon fiber for use as a material for a negative electrode of a secondary battery, and a process for producing the same. The mesophase pitch-based carbon fiber comprises a columnar core part having a texture composed of a plurality of graphite layers extending along an axial direction and extending with minute flexures in a plane perpendicular to the axis and an outer-shell part surrounding the core part. The outer-shell part has a texture composed of a laminate of a plurality of graphite layers extending along an axial direction. The graphite layers are oriented in a plane perpendicular to the axis in a fashion such that the graphite layers extend along a circumferential direction with minute flexures while gradually receding from a center of the core part.

Abstract: A process for producing an activated carbon fiber molding is disclosed which comprises spinning an isotropic pitch to thereby obtain pitch fibers, infusibilizing the pitch fibers to thereby obtain infusibilized fibers, heating the infusibilized fibers under a mechanical load to thereby obtain a molding and activating the molding. In this process, the infusibilized fibers and/or infusibilized fibers molding may be heated in an inert atmosphere so as to effect a light carbonization thereof and thereafter subjected to the subsequent step of the process. The pitch-based porous activated carbon fiber molding obtained by this process has a strikingly high bulk density and can sufficiently exhibit the specific properties of the activated carbon fiber, e.g. a large specific surface area, to thereby have a high adsorption efficiency.

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: Disclosed is a process for preparing milled graphite fibers in which the amount of metallic components contained in the milled carbon fibers before graphitizing is limited to not more than 100/1,000,000 in terms of a ratio by weight. Also disclosed is a process for preparing milled graphite fibers in which the amount of metallic components contained in the milled carbon fibers before graphitizing except metallic components originally contained in the fibers themselves is limited to not more than 50/1,000,000 in terms of a ratio by weight. According to these processes, there can be obtained milled graphite fibers whose surfaces are inert, which suffer few longitudinal crackings and which are almost free from occurrence of particulate substances comprising agglomerated or bonded fibers.

Abstract: There is provided an optically isotropic pitch-based activated carbon fiber which comprises having a large number of pores each with a radius of 0.15 to 2.5 nm and having a specific surface area of 500 m.sup.2 /g or more, the pores being distributed uniformly in both the surface layer part and the inner part of the fiber and allowed to three-dimensionally communicate with each other at least partially.The above activated carbon fiber is prepared by adjusting the size and density of the pores in the fiber by controlling the conditions for preparing the optically isotropic pitch, spinning the pitch and/or activation of the infusibilized or carbonized pitch-based fiber.The activated carbon fiber thus obtained is enhanced in adsorption efficiency without decrease in mechanical strength thereof and is widely used for a variety products in accordance with the kind of the substances to be adsorbed.

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: A carbon material for use in a lithium secondary battery, which is obtained by graphitization conducted in the presence of a boric compound so as to contain boron in an amount ranging from 1,000 ppm to 30,000 ppm and which, when subjected to X-ray diffractometry, exhibits an interplanar spacing of 002 surface (d.sub.002) of not greater than 0.338 nm, a crystallite size along c-axis (Lc) of at least 35 nm, a crystallite size along a-axis (La) of at least 50 nm and a ratio of diffraction peak (101) to diffraction peak (100), designated as P.sub.101 /P.sub.100, of at least 1.0; a negative electrode and a lithium secondary battery each produced by using the above carbon material; and a process for producing the carbon material. This carbon material exhibits large charge and discharge capacities, so that it can provide a negative electrode for use in a lithium secondary battery which is excellent in charge and discharge cycle characteristics.

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: Carbon fiber rovings for reinforcement of concrete are here disclosed which are obtained by sizing, with a sizing agent, strands each consisting of 100 to 1,000 monofilaments of mesophase pitch-based carbon fibers, and then bundling the thus sized 5 to 100 strands into one roving.

Abstract: A process for preparing mesophase pitch based carbon fibers is disclosed, wherein mesophase pitch fibers are gas-phase nitrated in an atmosphere of an oxygen-containing gas such as air or an inert gas such as nitrogen containing 0.1 to 50% by volume of NO.sub.2 at a low temperature of not higher than 100.degree. C. for a long period of time. The carbon fibers thus obtained are excellent in both mechanical strength and elastic modulus and have well-balanced physical properties.

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 preparing nitrogen-containing isotropic pitch, comprising the steps of mixing a petroleum heavy oil, a nitrating reagent and water to prepare a homogeneous dispersion, thereby contacting the petroleum heavy oil with the nitrating reagent in the homogeneous dispersion state to prepare a crude nitrated heavy oil, and subjecting the crude nitrated heavy oil to refining, thermal polymerization and vacuum distillation. According to the process of the invention, a petroleum heavy oil containing a large amount of light oil components and being liquid at ordinary temperature, from which pitch has been hardly prepared conventionally, is used as a starting material for preparing pitch, and there can be obtained nitrogen-containing isotropic pitch of homogeneity and high quality having a desired softening point of from a low softening point to a high softening point, though such pitch was unable to be obtained so far.

Abstract: A negative electrode for use in a secondary battery is disclosed, comprising milled carbon fibers derived from mesophase pitch wherein the milled carbon fibers each has a fiber cut surface and a fiber axis intersecting with each other at cross angles, the smaller one thereof being at least 65.degree. on the average. This negative electrode does not suffer from property deterioration, irrespective of multiple repetitions of charge and discharge, from which a nonaqueous-electrolyte-loaded lithic secondary battery having excellent cycle characteristics can be fabricated.