Abstract: A method is provided for the preparation of polycarbonates by the reaction of a diaryl carbonate, such as DPC and a dihydric phenol, such as BPA. The method utilizes the steps of successively processing the diaryl carbonate and the dihydric phenol in a melt in a first reaction stage, a second reaction stage and at least a first polymerization stage, and shifts the processing conditions such that the desired low viscosity/high end-cap product is obtained. This is achieved by having the ratio of diaryl carbonate to dihydric phenol in the melt prior to the first reaction stage greater than 1.08; and by controlling the temperature and residence time in the first polymerization stage to provide a polycarbonate product having a melt flow rate at 250° C. of greater than 10 g/min and an end-cap level of at least 90%. The method of the invention can be used in a linear manufacturing process, in which there is one product produced.

Abstract: To provide a manufacturing apparatus with which it is possible to manufacture a polycarbonate that has superior residence stability such as its coloring stability and thermal stability during melt molding, and that has a low content of foreign matter. An apparatus for manufacturing a polycarbonate by the melt polycondensation of a bisphenol and a carbonic diester, wherein said apparatus for manufacturing a polycarbonate is characterized in that: (1) the equipment surfaces that come into contact with the molten raw materials and the reaction product thereof at 250° C. or lower are made of nickel; and (2) the equipment surfaces that come into contact with the molten raw materials and the reaction product thereof above 250° C. are made of stainless steel with a nickel content of 5 to 15% and a chromium content of 10 to 20%.

Abstract: The specification provides a method for the manufacture of a high-quality optical polycarbonate that contains few inorganic or organic impurities or other microparticles, and that has a superior hue. Specifically, the specification provides a method for the manufacture of a polycarbonate by the melt polycondensation of a bisphenol and a carbonic diester, wherein the molten mixture of a bisphenol and a carbonic diester is filtered with a membrane filter made of a fluororesin, after which melt polycondensation is conducted.

Abstract: Improved performance in high temperature, high vacuum reactors is obtained by quenching alkaline catalyst present in the product a melt polycondensation reaction using a sulfonic acid ester quencher in a carrier. The carrier if formed from a first carrier component effective to solubilize the quencher and having a lower boiling point than the quencher, and a second carrier component soluble in the first carrier component and having a higher boiling point than the quencher. An exemplary carrier composition contains equal parts of diphenylcarbonate and toluene.

Abstract: A method for determining the effective level of catalyst for the preparation of a polycarbonate polymer by a transesterification reaction is disclosed. The method involves measurement of the leaving group by-product (usually phenol) produced in a test reaction between an aromatic dihydroxy compound and a carbonic acid diester, in the presence of a known amount of transesterification catalyst. The by-product production values can be compared with by-product reference values to calculate the effective level of catalyst. This data can be used to efficiently control catalytic activity in a production scale reaction for producing polycarbonate polymer.

Abstract: A filter for high-viscosity fluids can be used in small to large-sized units, shows no thermal deterioration of the contents, and allows simple, rapid, and safe exchanging of the filter units and has a structure in which at least one filter element is built in, such that when a filter unit having an inlet opening and an outlet opening has the aforementioned inlet opening attached to the outlet opening of the unit on the upstream side and the aforementioned outlet opening attached to the inlet opening of the unit on the downstream side, two supporting plates, one fixed and one movable, are attached to an inlet-side adapter and an outlet-side adapter, the aforementioned filter unit is surrounded by said fixed supporting plate and movable supporting plate, and by moving the movable supporting plate, the various connecting parts can be closed and opened.

Abstract: A manufacturing method for polycarbonate comprising ?I! a process for manufacturing diaryl carbonate from an aromatic hydroxy compound and an aromatic hydroxy compound, ?II! a process for manufacturing polycarbonate by solution polymerization of the diaryl carbonate obtained in ?II! and an aromatic dihydroxy compound in the presence of a catalyst comprising a nitrogen-containing basic compound, and ?III! a process for separating and removing the nitrogen-containing compound from the aromatic hydroxy by-products in ?II! and returning the resultant aromatic hydroxy compounds to process ?I! effectively reuses aromatic hydroxy by-products (e.g., phenols) of polycarbonate manufacturing to manufacture diaryl carbonate, while suppressing the production of alkyl aromatic ethers and then uses this diaryl carbonate to manufacture polycarbonate with good productivity.

Abstract: Aromatic polycarbonates manufactured by polycondensation of a dihydric compound and a carbonic acid diester using at least two reactors in series have improved color and low impurities content when filtered before the final reactor and again before the final reactor outlet.

Abstract: The method of the present invention is a hot-melt polycondensation for an aromatic dihydroxy compound and a dicarbonate in the presence of a basic catalyst, adding sulfur-containing acid compound with a pKa value less than 3 or the derivative thereof, and 5-1,000 ppm of water, and additives as needed for the polycarbonate while the reaction product polycarbonate is still in a molten state, and kneading the material.

Abstract: Object: The present invention was conceived in light of the above-described prior art. The object of this invention is to provide a method for preparing optical-grade polycarbonate compositions, which method is able to prepare with good productivity optical-grade polycarbonate compositions that have not only excellent clarity and water resistance, but also excellent retention stability such as heat stability and hue stability when molten and a low content of inclusions and impurities, and that undergo little heat deterioration.Constitution: The method for preparing optical-grade polycarbonate compositions according to this invention, which method comprises the melt-polycondensation of an aromatic dihydroxy compound and a diester carbonate in the presence of a catalyst, followed by the addition of additives B! while the polycarbonate A! obtained as the reaction product is in a molten state, and mixing.

Abstract: Object: The present invention was conceived in light of the above-described prior art. The object of this invention is to provide a method for preparing optical-grade polycarbonate compositions, which method is able to prepare with good productivity optical-grade polycarbonate compositions that have not only excellent clarity and water resistance, but also excellent retention stability such as heat stability and hue stability when molten and a low content of inclusions and impurities, and that undergo little heat deterioration.Constitution: The method for preparing optical-grade polycarbonate compositions according to this invention, which method comprises the melt-polycondensation of an aromatic dihydroxy compound and a diester carbonate in the presence of a catalyst, followed by the addition of additives [B] while the polycarbonate [A] obtained as the reaction product is in a molten state, and mixing.