Abstract: A carbon fiber having a total content of Li, Na, Ti, Mn, Fe, Ni and Co metal elements of no more than 50 ppm and a fiber diameter of 0.001 to 2 ?m and not branched and a assembly of a plurality of the carbon fibers.

Abstract: A carbon fiber nonwoven fabric comprising an aggregate of carbon microfibers having a fiber diameter of 0.001 to 2 ?m and a production method thereof are provided. The nonwoven fabric is useful as a substrate, precursor and material for a fuel cell electrode. The nonwoven fabric can be mixed with a resin to be used as a composite material and can carry metal to be used in a filter.

Abstract: A fibrous active carbon having pores in the surface, wherein the pore diameter falls within a range of 0.1 to 200 nm, and, the active carbon is in the form of a fiber, and has a fiber diameter of less than 1000 nm or less.

Abstract: A process for manufacturing a carbon fiber having a fiber diameter of 0.001 to 5 ?m and a narrow fiber size distribution, and a resin composition suitable for the manufacture of a carbon fiber. A resin composition comprising 100 parts by weight of a thermoplastic resin, 1 to 150 parts by weight of a carbon precursor organic compound (A) and 0.001 to 40 parts by weight of acopolymer of polymer segments (e1) and (e2) which satisfy a specific range of surface tension for the thermoplastic resin and a specific range of surface tension for the carbon precursor organic compound (A) at the same time.

Abstract: A polycarbonate composition comprising 100 parts by weight of an aromatic polycarbonate, 0.005 to 0.2 part by weight of an ester of an aliphatic monocarboxylic acid having 10 to 25 carbon atoms and an aliphatic polyhydric alcohol having 2 to 10 carbon atoms, and 0.015 to 0.3 part by weight of a first aromatic compound which is an aromatic ether, ester or carbonate compound having at least four benzene rings in the molecule, wherein the above ester is contained in the above range to ensure that the first aromatic compound is contained in a deposit on the polymer contacting surface of a metal mold in an amount of 0.5 to 3 parts by weight based on 1 part by weight of the ester when a 120 mm x 50 mm board having a thickness of 2 mm is injection molded at a cylinder temperature of 380° C., a mold temperature of 80° C., an injection speed of 200 mm/sec and a holding pressure of 3,432 kPa (35 kgf/cm2).

Abstract: An aromatic polycarbonate depolymerization method comprising reacting an aromatic polycarbonate with water, an aliphatic alcohol having 1 to 6 carbon atoms or a phenol which may be substituted by a hydrocarbon group having 1 to 10 carbon atoms in the critical fluid of carbon dioxide or with the critical fluid of an aliphatic alcohol having 1 to 6 carbon atoms or a phenol which may be substituted by a hydrocarbon group having 1 to 10 carbon atoms.

Abstract: An aromatic polycarbonate composition which is suitable for use in the production of an optical molded article such as an optical disk or lens and has excellent heat stability and releasability at the time of molding. This composition comprises 100 parts by weight of an aromatic polycarbonate obtained by reacting an aromatic dihydroxy compound with a carbonic acid diester in the presence of at least one ester exchange catalyst selected from the group consisting of an alkali metal compound and an alkali earth metal compound, 0.0001 to 0.3 part by weight of an epoxy compound and 0.015 to 0.3 part by weight of an aromatic compound having at least four benzene rings in the molecule.

Abstract: A method of producing a polycarbonate or the like which is excellent in hydrolysis and heat stability such as a reduction in molecular weight at the time of molding and color retention and moldability such as releasability and transferability, rarely experiences residence deterioration such as coloring, crosslinking and gel formation and has an extremely small content of foreign matter by employing a special structure for an opening in the side surface of a horizontal cylindrical vacuum resin treating apparatus, supplying a molten polycarbonate into a unidirectional rotary intermeshing double-screw extruder under specific conditions, adding a specific agent under specific conditions and cleaning the inner surface of a production apparatus by a specific method.

Abstract: A polycarbonate having excellent color, a low content of foreign substances, a low content of an OH terminal group, little quality variation and excellent moldability and a production method therefor.

Abstract: A process for the production of a polycarbonate, capable of measuring the amounts of an aromatic dihydroxy compound and a carbonic acid diester or the ratio of the carbonic acid diester to the aromatic dihydroxy compound quickly and efficiently and adjusting it to obtain a polycarbonate having high quality with little variations.

Abstract: An aromatic polycarbonate composition which contains 0.05 to 65 ppm of bonded phosphorus atoms to polycarbonate chains and free phosphorus compounds consisting of a tervalent phosphorus compound and a pentavalent phosphorus compound in a specific ratio. It is excellent in transparency, color stability and residence stability at the time of molding and is suitably used in disk substrates.

Abstract: A polycarbonate resin composition which is excellent in thermal stability such as color retention at the time of melt molding, for example, the prevention of yellowing, and moldability such as releasability and transferability and therefore particularly suitable for the production of precision optical moldings such as optical disk substrates and lenses. The polycarbonate resin composition comprises (A) an aromatic polycarbonate, and (B) a cyclic carbonate compound, a monoester compound of a divalent aliphatic alcohol having 3 to 14 carbon.

Abstract: Aromatic polycarbonate having a reduced discoloration and improved heat stability, hue, etc. is provided by keeping a pressure in a raw material melting vessel and the linear velocity of a gas in a transporting piping in a specific range, keeping the concentration of a nitrogen-containing basic compound in a specific range, recycling a byproduct containing specific amounts of impurities, suppressing the amounts of a nitrogen-containing basic compound, metallic elements and a silicic acid derivative in the carbonic acid diester at specific values or less, prescribing the material quality of the reaction facilities, and/or forming an oxide layer at the inner wall surfaces of the reaction facilities.

Abstract: A process for the production of a stabilized polycarbonate which comprises melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a polycondensation catalyst and then, after the reaction mixture shows an intrinsic viscosity of at least 0.1, adding at least one stabilizer selected from the group consisting of specific compounds having a sulfonates group sulfonic acid anhydride group or a sulfate group in an amount of 0.01 to 500 ppm of a polycarbonate to be formed, to form a polycarbonate having a desired intrinsic viscosity.

Abstract: A process for the production of an aromatic polycarbonate, which comprises polycondensing an aromatic dihydroxy compound and a diaryl carbonate in the presence, as a polycondensation catalyst, of at least one alkali metal salt selected from the group consisting of alkali metal salts of ate-complexes of a metal element, which is silicon, germanium, stannum or plumbum, and alkali metal salts of oxoacids of said metal elements. The above aromatic polycarbonate is almost free from being colored, is also almost free from a decrease in polymerization degree when molded, and is further almost free from forming branches and insolubles.

Abstract: A process for the production of a stabilized polycarbonate which comprises melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a polycondensation catalyst and then, after the reaction mixture shows an intrinsic viscosity of at least 0.1, adding at least one stabilizer selected from the group consisting of specific compounds having a sulfanate group and a sulfonic acid anhydride group in an amount of 0.01 to 500 ppm of a polycarbonate to be formed, to form a polycarbonate having a desired intrinsic viscosity.

Abstract: A process for the production of a stabilized polycarbonate which comprises melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a polycondensation catalyst and then, after the reaction mixture shows an intrinsic viscosity of at least 0.1, adding at least one stabilizer selected from the group consisting of specific compounds having either a sulfonate group, a sulfonic acid anhydride group or a sulfate group in an amount of 0.01 to 500 ppm of a polycarbonate to be formed, to form a polycarbonate having a desired intrinsic viscosity.