Abstract: Provided is an aromatic polycarbonate resin composition which comprises 100 parts by mass of an aromatic polycarbonate resin and from 0.001 to 1 part by mass of an additional thermoplastic resin that differs from the aromatic polycarbonate resin in the refractive index by at least 0.001 and which is so designed that the ratio (X)/(Y) is at least 0.5 wherein (X) indicates the spectral transmittance at 320 nm through a sample plate of the resin composition having a thickness of 2 mm and (Y) indicates the spectral transmittance at 633 nm through it. Having realized further increase in the transparency of aromatic polycarbonate resin, the resin composition gives moldings of which the transparency is comparable to that of acrylic resin for optical use, and the resin moldings have good impact resistance and heat resistance.

Abstract: Disclosed are an optical waveguide that comprises (A) a copolyester carbonate having aliphatic segment(s), and a method for producing it; and an optical waveguide made from a polycarbonate resin composition that comprises (A) a copolyester carbonate having aliphatic segment(s) and (B) an aromatic polycarbonate, and a method for producing it. The polycarbonate resin composition for the optical waveguide has the advantages of high mechanical strength and improved flowability.

Abstract: Provided is an aromatic polycarbonate resin composition which comprises 100 parts by mass of an aromatic polycarbonate resin and from 0.001 to 1 part by mass of an additional thermoplastic resin that differs from the aromatic polycarbonate resin in the refractive index by at least 0.001 and which is so designed that the ratio (X)/(Y) is at least 0.5 wherein (X) indicates the spectral transmittance at 320 nm through a sample plate of the resin composition having a thickness of 2 mm and (Y) indicates the spectral transmittance at 633 nm through it. Having realized further increase in the transparency of aromatic polycarbonate resin, the resin composition gives moldings of which the transparency is comparable to that of acrylic resin for optical use, and the resin moldings have good impact resistance and heat resistance.

Abstract: Disclosed are a flame-retardant polycarbonate resin composition comprising, as the essential ingredients, (A) a polycarbonate resin, (B) a specific styrenic resin, and (C) a specific phosphate compound, and its moldings. Containing no halogen, the resin composition and its moldings have good flame retardancy, impact strength, heat-resistant stability, thermal aging resistance, and wet heat resistance.

Abstract: Disclosed are polycarbonates which are obtained by preparing a polycarbonate prepolymer through prepolymerization followed by polymerizing it through solid-phase, swollen solid-phase or thin film melt-phase transesterification, and have a remaining monomer content of smaller than 100 ppm, especially a dihydroxy compound content of smaller than 100 ppm, or have an acetone soluble content of at most 3.5 or at most 3.0% by weight, or have a terminal hydroxyl fraction of smaller than 2 or smaller than 15 mol %; and optical materials and blow molding materials comprising the polycarbonate. The polycarbonates contain a reduced amount of impurities such as remaining monomers, oligomers and others and have improved physical properties including impact strength, and these are useful as optical materials and blow molding materials.

Abstract: Provided are a polycarbonate resin composition comprising 100 parts by weight of a polycarbonate and from 0.001 to 15 parts by weight of a benzotriazole-type UV absorbent and/or a benzophenone-type UV absorbent, and having a sulfur content of at most 50 ppb; and its sheet moldings. The resin composition and its sheet moldings have good weather resistance and heat stability.

Abstract: Provided are a method for producing polycarbonates through melt transesterification, wherein is used a polymerization catalyst comprising a phosphorus-containing basic compound and a quaternary phosphonium salt having a specific structure; and a method for producing polycarbonates, which comprises pre-polymerization to prepare polycarbonate prepolymers followed by final polymerization of said prepolymers in a solid phase or in a swollen solid phase to produce the products, polycarbonates, and in which (1) a catalyst comprising a phosphorus-containing basic compound and a quaternary phosphonium salt having a specific structure is used in the pre-polymerization and in the final polymerization, or (2) a catalyst of a tri-valent or penta-valent phosphorus compound or a nitrogen-containing organic basic compound is used in the final polymerization, or (3) the final polymerization is effected in a vapor-phase atmosphere having an oxygen concentration of not larger than 2 ppm.

Abstract: A digital video disk substrate of a polycarbonate having a viscosity average molecular weight (Mv) of 10,000 to 17,000 and a weight average molecular weight (Mw)/number average molecular weight (Mn) of not smaller than 2.3, and a digital video disk substrate of a polycarbonate having a viscosity average molecular weight (Mv) of 1,000 to 17,000 obtained by the transesterification of a divalent phenol such as 2,2-bis(4-hydroxyphenyl) propane with a carbonic acid diester such as diphenyl carbonate. The digital video disk substrate is little cracked at the time of molding, and exhibits small birefringence and excellent transcriptional property.

Abstract: There are disclosed a process for producing a polycarbonate through transesterification which comprises using, as a polymerization catalyst, (1) a combination of a nitrogen-containing organic basic compound and a quaternary phosphonium salt, (2) a tetraarylphosphonium salt having a specific chemical structure, or (3) a quaternary phosphonium salt having a specific chemical structure and containing a branched alkyl group; and a process for producing a polycarbonate which comprises the steps of preparing a polycarbonate prepoplymer by preliminary polymerization and thereafter polymerizing the resultant prepolymer in a state of a solid phase by the use of a quaternary phosphonium salt as a catalyst.By using any of these processes it is made possible to produce, in extremely high efficiency, a high-quality polycarbonate being excellent in appearance, heat resistance, hydrolysis resistance and the like.

Abstract: The present invention is directed to a process for preparing a polycarbonate in accordance with an ester exchange reaction of a dihydroxy compound (A) and a carbonic acid diester (B) by adjusting, to 2 ppm or less, the concentration of oxygen in an atmosphere in which the ester exchange reaction is carried out.According to the present invention, there can efficiently be prepared the polycarbonate which is free from residence burn and which is excellent in hydrolysis resistance and color tone.

Abstract: A process for producing a branched polycarbonate which comprises using a branching agent containing 200 ppm or less of sulfur; a branched polycarbonate which is prepared by the interfacial method and contains 1.0 ppm or less of residual sulfur as an impurity; and a branched polycarbonate which is prepared by the melting method and contains 2.0 ppm or less of residual sulfur as an impurity; are provided. When the branched polycarbonate is produced by the interfacial method, the branched polycarbonate produced does not show deterioration in heat stability or cause mold corrosion. When the branched polycarbonate is produced by the melting method, the branched polycarbonate produced does not show deterioration in heat stability or in color tone.

Abstract: A process for producing a branched polycarbonate which comprises using a branching agent containing 200 ppm or less of sulfur; a branched polycarbonate which is prepared by the interfacial method and contains 1.0 ppm or less of residual sulfur as an impurity; and a branched polycarbonate which is prepared by the melting method and contains 2.0 ppm or less of residual sulfur as an impurity; are provided. When the branched polycarbonate is produced by the interfacial method, the branched polycarbonate produced does not show deterioration in heat stability or cause mold corrosion. When the branched polycarbonate is produced by the melting method, the branched polycarbonate produced does not show deterioration in heat stability or in color tone.

Abstract: A phase difference compensation film formed of a polycarbonate, which can be used in a liquid crystal display and which shows a decreased change in retardation caused by a temperature change at a stretch forming time due to the use of a polycarbonate having a branched structure and having a viscosity-average molecular weight of 40,000 or less as the above polycarbonate.

Abstract: A process for producing a polycarbonate, which comprises transesterifying, in the presence of an antioxidant, (A) a dihydroxy compound or a precursor thereof and (B) a carbonic acid diester having, as an impurity, a chlorine content derived from chloroformate group of at most 30 ppm, which is determined by subtracting the chlorine content extracted with water using ion chromatography from the total chlorine content contained in said carbonic acid diester determined by potentiometric titration.

Abstract: There is disclosed a process for producing a polycarbonate which comprises reacting, by the melt method, (A) a dihydroxy compound with (B) a carbonic diester having a chloride contempt derived from chloroformate group of not more than a prescribed level. According to the above process, a polycarbonate which is excellent in transparency, tone of color, heat resistance and water resistance can be efficiently and economically produced.

Abstract: A polycarbonate having desirable color tone or transparency, as well as desirable heat resistance and water resistance, in which the amounts of residual metals in the polycarbonate are 10 ppm or less in total of Fe, Cr and Mo and 50 ppm or less in total of Ni and Cr. The polycarbonate is obtained by transesterification of (A) a dihydroxy compound and (B) a carbonic diester in a reactor made of a metallic material containing at least one metal selected from the group consisting of Fe, Cr, Mo, Ni and Cu, and controlling the water content in the reactor to 500 ppm or less.

Abstract: A process for producing polycarbonates which comprises transesterifying by reacting (A) at least one compound selected from the group consisting of aromatic dihydroxy compounds, aliphatic dihydroxy compounds, bisesters of aromatic dihydroxy compounds, bisesters of aliphatic dihydroxy compounds, carbonates of aromatic dihydroxy compounds and carbonates of aliphatic dihydroxy compounds, with (B) at least one compound selected from the group of diaryl carbonates, dialkyl carbonates, and alkylaryl carbonates, at a transesterification temperature of 100.degree. C. to 330.degree. C. in the presence of an inert solvent in an amount of 1 to 60% by weight based on the total of the theoretical amount of polycarbonate produced from the said compounds (A) and (B) and the amount of the inert solvent. According to the present invention, a polycarbonate which is excellent in color tone (transparency), heat resistance, and water resistance can be efficiently and simply produced at a low cost.

Abstract: A polycarbonate resin composition comprising 1 to 99% by weight of a branched polycarbonate having a branched nucleus structure derived from a branching agent represented by the general formula: ##STR1## wherein R is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R.sup.1 to R.sup.6 are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms or halogen atoms, respectively, and 99 to 1% by weight of a thermoplastic polyester resin. The polycarbonate resin composition is excellent in fluidability, solvent resistance and moldability.

Abstract: Disclosed herein is a polycarbonate copolymer comprising repeating units respectively made of a bisphenol A and a tetrahalogenobisphenol A and having a trihalogenophenoxy group as an end group at the terminal, particularly both terminals thereof and a method for efficiently producing said polycarbonate copolymer. This polycarbonate copolymer is superior in impact resistance, flame retardance, molding thermostability and the like, is good in hydrolytic resistance, is much less liable to cause a mold rust and has high quality. Therefore, this polycarbonate copolymer will be extensively used in various industrial materials, for example as the flame retardant parts for household electric appliances, office automation apparatuses and the like.

Abstract: A process for producing a branched polycarbonate comprising reacting a dihydric phenol, such as 2,2-bis(4-hydroxyphenyl) propane, a polyfunctional organic compound, such as 1,1,1-tris-(4-hydroxyphenyl)ethane, and phosgene to produce a polycarbonate oligomer, and then polycondensing with stirring the polycarbonate oligomer with a dihydric phenol, such as 2,2-bis(4-hydroxyphenyl) propane, and a monohydric phenol, such as p-tert butylphenol, whereby the interfacial area of the resultant emulsion is not less than 40 m.sup.2 /L.