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 having excellent color is obtained by keeping an aromatic dihydroxy compound and a carbonic acid diester which are raw materials for the production of an aromatic polycarbonate in consideration of the influences of storage atmosphere, temperature, temperature difference from a storage tank and residence time.

Abstract: An aromatic polycarbonate resin is produced under the conditions that the flow velocity of the reaction mixture in a pipe through which a molten reaction mixture passes is a specific value or over, the viscosity-average molecular weight of the reaction mixture is 1,000 or more, the sum of the average retention times of the reaction mixture is not longer than 3 hours, the wall temperature of the pipe through which a molten reaction mixture passes is set to be higher than the temperature of the reaction mixture in the pipe, the catalyst deactivation agent is added within 2 hours after the completion of the melt polycondensation reaction, the filtration is carried out by using a filter having a specific retained particle size under a specific pressure difference, specific treated amount of the aromatic polycarbonate resin per unit area of the filter and a ratio of W (flow quantity of filtered polymer)×1,000/A (maximum area of the polymer path in the filtration vessel) falling within a specific range, etc.

Abstract: Provided are a filtration apparatus for a polycarbonate comprising a filtration container, a flange plate, one or more leaf disc-type filters, a filter press and a center pole having an integral construction with the filter press as constituting elements, these components having specific structures, and a process for manufacturing a polycarbonate using the filtration apparatus. Foreign materials are effectively removed by using the polymer filter, and at the same time, discoloring, crosslinking and gel formation, which would occur in the filter, are suppressed; and as a result, a polycarbonate having excellent quality can be manufactured.

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: A method of cleaning the aromatic polycarbonate production unit with a carbonic acid diaryl ester at a temperature of 200 to 350° C. in an inert gas atmosphere.

Abstract: Purpose To enable the reduction of the quantities of wastes and the performance of long term continuous operation in polycarbonate production. Means for solution As a method for removing the reaction byproducts in the production of a polycarbonate resin by sucking and reducing the pressure, ejectors which use the vapor of a substance comprising the condensed liquid of the reaction byproducts as the driving source are used, and the wall temperatures of piping between a polymerization reactor and the ejectors are held at a temperature equal to the boiling point of said reaction byproducts at reduced pressure or higher.

Abstract: An aromatic polycarbonate resin is produced under the conditions that the flow velocity of the reaction mixture in a pipe through which a molten reaction mixture passes is a specific value or more, the viscosity-average molecular weight of the reaction mixture is 1,000 or more, the sum of the average retention times of the reaction mixture is not longer than 3 hours, the wall temperature of the pipe through which a molten reaction mixture passes is set to be higher than the temperature of the reaction mixture in the pipe, the catalyst deactivation agent is added within 2 hours after the completion of the melt polycondensation reaction, the filtration is carried out by using a filter having a specific retained particle size under a specific pressure difference, specific treated amount of the aromatic polycarbonate resin per unit area of the filter and a ratio of W (flow quantity of filtered polymer)×1,000/A (maximum area of the polymer path in the filtration vessel) falling within a specific range, etc.

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 producing an aromatic polycarbonate through an ester interchange reaction between an aromatic carbonic acid diester and an aromatic dihydroxy compound, wherein the aromatic carbonic acid diester is obtained through the decarbonylation reaction of an aromatic oxalic acid diester represented by the following general formula (1): wherein two Ar's are the same or different aromatic hydrocarbon groups having 6 to 14 carbon atoms, and has a hydrolyzable halogen content of 5 ppm or less. According to the present invention, an aromatic polycarbonate having a high molecular weight and excellent color can be easily produced without impairing ester interchange reactivity for the production of the aromatic polycarbonate by using an aromatic carbonic acid diester obtained through the decarbonylation of an aromatic oxalic acid diester and controlling the amount of hydrolyzable halogen contained in the aromatic carbonic acid diester to a value smaller than a predetermined value.

Abstract: A process for producing a polycarbonate resin through the melt polycondensation of an aromatic diol compound and a carbonic acid diester compound, wherein (1) valves, (2) gear pumps, (3) flanges and (4) flow passages having the specified structures and characteristic properties are used in the production process. According to the present invention, a high-quality polycarbonate can be obtained by an industrial process.

Abstract: The purpose of this invention is to produce a stabilized terminal-blocked polycarbonate resin with a limited number of the terminal hydroxy groups having excellent thermal stability, color stability and hydrolysis resistance by an industrially advantageous method using a terminal blocking agent. In the production of a polycarbonate by the melt-polycondensation of an aromatic dihydroxy compound with an aromatic carbonic acid diester in the presence of a polycondensation catalyst, a terminal blocking agent expressed by the following formula (1) [in the formula, R1 is chlorine atom, methoxycarbonyl group or ethoxycarbonyl group; R2 is an alkyl group having a carbon number of 1 to 30, an alkoxy group having a carbon number of 1 to 30, an aryl group having a carbon number of 6 to 30 or an aryloxy group having a carbon number of 6-30] is added after the melt-polycondensation to the system in an amount of 0.

Abstract: A viscous liquid stirring device comprising a first rotary shaft and a second rotary shaft which are arranged in parallel to each other in the horizontal plane in the vessel. The rotary shafts have a plurality of rotors thereon and are rotated at the same speed and in the same direction that the upper face of the first rotary shaft moves away from the second rotary shaft. A viscous liquid inlet portion is formed on the top portion of the inner wall of the end plate of the vessel.

Abstract: A shaped silicon carbide-based ceramic article having an improved mechanical strength is produced at a high efficiency by a process comprising the step of: forming an organic silicone polymer, for example, polycarbosilastyrene copolymer, into a predetermined shape, for example, a filament or film; doping the shaped polymer with a doping material consisting of at least one type of halogen, for example, bromine or iodine, in an amount of 0.01% to 150% based on the weight of the shaped polymer, to render the shaped polymer infusible; and pyrolyzing the infusible shaped polymer into a shaped SiC-based ceramic article at a temperature of 800.degree. C. to 1400.degree. C. in an inert gas atmosphere, optionally the halogen-doped shaped polymer being treated with a basic material, for example, ammonia, before the pyrolyzing step, to make the filament uniformly infusible.

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 shaped silicon carbide-based ceramic article having an improved mechanical strength is produced at a high efficiency by a process comprising the step of: forming an organic silicon polymer, for example, polycarbosilastyrene copolymer, into a predetermined shape, for example, a filament or film; doping the shaped polymer with a doping material consisting of at least one type of halogen, for example, bromine or iodine, in an amount of 0.01% to 150% based on the weight of the shaped polymer, to render the shaped polymer infusible; and pyrolyzing the infusible shaped polymer into a shaped SiC-based ceramic article at a temperature of 800.degree. C. to 1400.degree. C. in an inert gas atmosphere, optionally the halogen-doped shaped polymer being treated with a basic material, for example, ammonia, before the pyrolyzing step, to make the filament uniformly infusible.

Abstract: A process for the preparation of high-performance grade carbon fibers, which comprises attaching a fine powder of at least one member selected from oxides and carbides of silicon, aluminum, titanium, and boron to a precursor fiber bundle of as spun pitch fibers, subjecting the fiber bundle to an infusibilization treatment, and subjecting the fiber bundle to a carbonization treatment.

Abstract: A pitch-based carbon or graphite fiber having a leafy lamella arrangement in at least 30% of the fiber cross-sectional area and having a tensile strength of at least 300 kg/mm.sup.2. The fiber is prepared by melt-spinning an optically anisotropic pitch having an optically anisotropic phase content of at least 50% through a spinneret in which at least one central line distance in a spinning hole simultaneously satisfies the following requirements I and II,Ln<10 I1.5.ltoreq.Ln/Wn.ltoreq.20 IIwherein Ln stands for central line distances in mm in the spinning hole and Wn stands for wetted perimeter widths in mm in the spinning hole, and infusibilizing and carbonizing the formed pitch fiber.