Abstract: A process for producing a cycloolefin resin composition comprising a cycloolefin resin and an additive by using a twin-screw extruder is provided, in which loss of the additive caused by volatilization through a vent during kneading is reduced and kneading of resin material with the additive can be sufficiently carried out. When the cycloolefin resin and the additive are kneaded by using a vented twin-screw extruder (10) to produce the cycloolefin resin composition containing the additive, an additive introduction opening (3) is disposed downstream of a vent (2) located nearest to a discharge opening (13) of the twin-screw extruder, and the additive is charged through the additive introduction opening located at a distance from the discharge opening of the twin-screw extruder in the range between longer than 10D and not longer than 30D.

Abstract: A process for producing a cycloolefin resin composition comprising a cycloolefin resin and an additive by using a twin-screw extruder is provided, in which loss of the additive caused by volatilization through a vent during kneading is reduced and kneading of resin material with the additive can be sufficiently carried out. When the cycloolefin resin and the additive are kneaded by using a vented twin-screw extruder (10) to produce the cycloolefin resin composition containing the additive, an additive introduction opening (3) is disposed downstream of a vent (2) located nearest to a discharge opening (13) of the twin-screw extruder, and the additive is charged through the additive introduction opening located at a distance from the discharge opening of the twin-screw extruder in the range between longer than 10D and not longer than 30D.

Abstract: A process for producing a polyethylene terephthalate in which the amount of the oligomers, such as cyclic trimer etc., is lower and which causes metal mold staining to occur difficultly. The process comprises an esterification stage in which dicarboxylicacids including mainly terephthalic acid or ester-forming derivatives of such acids are esterified with glycols including mainly ethylene glycol or with ester-forming derivatives of such glycols; a liquid phase polycondensation stage in which the esterified product obtained in the esterification stage is subjected to a polycondensation in a liquid phase containing a polycondensation catalyst and having a content of an alkaline solubilizing agent of 0.

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: 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.

Abstract: A substantially linear polyhydroxy polyether, which (1) is composed substantially of aromatic units and aliphatic units, the proportion of the aromatic units being 50 to 98 mole % based on the total amount of the aromatic units and the aliphatic units, (2) has an intrinsic viscosity, measured at 25.degree. C. in o-chlorophenol, of from 0.3 to 2 dl/g, and (3) has a glass transition, temperature of from 30.degree. to 120.degree. C. Two processes for preparing the polyhydroxy polyether are proposed. The polyhydroxy polyether is useful in applications which require gas-barrier property.