Abstract: A method of producing a polycarbonate, the method comprising: polymerizing a dihydric phenol and a carbonate precursor in the presence of a stabilizer to provide a polycarbonate with a yellowness index of less than or equal to 10 measured in accordance with ASTM E313 test method on molded samples having a thickness of about 2.5 millimeters; wherein the stabilizer is selected from the group consisting of ascorbic acid, salts of ascorbic acid, esters of ascorbic acid and a mixture of two or more of the foregoing; wherein the dihydric phenol is represented by Formula (I): wherein R is a hydrogen atom or an aliphatic functionality having 1 to 6 carbon atoms; and n is an integer having a value of 1 to 4.

Abstract: A dihydroxy aromatic compound having a Formula (I) wherein R1 is selected from the group consisting of a cyano functionality, a nitro functionality, an aliphatic functionality having 1 to 10 carbons, an aliphatic ester functionality having 2 to 10 carbons, a cycloaliphatic ester functionality having 4 to 10 carbons and an aromatic ester functionality having 4 to 10 carbons; R2 is selected from the group consisting of a cyano functionality, a nitro functionality, an aliphatic ester functionality having 2 to 10 carbons, a cycloaliphatic ester functionality having 4 to 10 carbons and an aromatic ester functionality having 4 to 10 carbons; and each R3 and R4, at each occurrence, can be the same or different and are independently at each occurrence an aliphatic functionality having 1 to 10 carbons or a cycloaliphatic functionality having 3 to 10 carbons, “n” is an integer having a value 0 to 4 and “m” is an integer having a value 0 to 4.

Abstract: A method for the manufacture of a polycarbonate which comprises reacting a carbonate precursor with a dihydroxy compound in the presence of an aqueous base in an inert organic solvent optionally containing a molecular weight regulator to form an oligomeric polycarbonate, wherein the reaction between the dihydroxy compound and the carbonate precursor is about 80 to about 99% completed; removing the inert organic solvent and the aqueous base to isolate the oligomeric polycarbonate; and transesterifying the isolated oligomeric polycarbonate to form a polymeric polycarbonate at a temperature and pressure effective to remove trace amounts of residual solvent. This method eliminates some of the problems of the prior art such as the removal of solvent from high molecular weight polycarbonate, which is both cumbersome, energy intensive and expensive.

Abstract: Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4?-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.

Abstract: A method is provided for reducing the color generated during production of copolycarbonate that includes quinone-type residues. The method includes the steps preparing a reaction mixture containing precursors of monomer residues, selecting a catalyst introduction strategy and adding catalysts according to the strategy. The strategy is sufficient to result in a product copolycarbonate with improved color. The method further includes the steps of introducing the reaction mixture to a series of process units and allowing the reaction mixture to polymerize thereby forming a copolycarbonate. The resulting copolycarbonate has improved color as compared to a copolycarbonate formed in a process without the steps of selecting a catalyst introduction strategy and introducing catalysts according to the selected strategy.

Abstract: A method is provided for reducing the color generated during production of copolycarbonate that includes quinone-type residues. The method includes the steps of mixing the precursors of monomer residues, a carbonate source and a polymerization catalyst into a reaction mixture. The method further includes the steps of introducing an antioxidant such as a hydroxycarboxylic acid to the reaction mixture in an amount sufficient to reduce color formation and introducing the reaction mixture to a series of process units wherein the reaction mixture polymerizes. The resulting copolycarbonate has improved color as compared to a copolycarbonate formed in a process without the step of introducing an antioxidant to the melt polymerization process.

Abstract: Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4?-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.

Abstract: A method for producing a thermoplastic sheet includes extruding a composition including a melt polycarbonate resin having a Fries content of about 10 ppm to about 2000 ppm. The composition enables the sheet to be extruded with excellent uniformity.

Abstract: A melt polymerization method is presented which permits the efficient preparation of copolycarbonates in which one or more of the constituent dihydroxy. aromatic compounds employed is relatively volatile, having a boiling point of less than about 340° C. Relatively volatile dihydroxy aromatic compounds are illustrated by dihydroxybenzenes such as hydroquinone, methyl hydroquinone and resorcinol. Known methods for the preparation of members of this class of copolycarbonates, such as the melt reaction of bisphenol A and resorcinol diphenyl carbonate in the presence of sodium hydroxide and tetraalkylammonium salt catalyst systems, suffer losses in efficiency due to the resorcinol being entrained out of the polymerization mixture with by-product phenol. Catalyst systems including quaternary phosphonium salts are shown to have improved performance with respect to the amount of volatile dihydroxy aromatic compound actually incorporated into the product copolycarbonate.

Abstract: A method for producing a thermoplastic sheet includes extruding a composition including a melt polycarbonate resin having a Fries content of about 10 ppm to about 2000 ppm. The composition enables the sheet to be extruded with excellent uniformity.

Abstract: Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4′-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.

Abstract: The invention relates to a method for the production of a branched polycarbonate composition, having increased melt strength, by late addition of branch-inducing catalysts to the polycarbonate oligomer in a melt polycondensation process. Surprisingly, it has been found that by adding branch-inducing catalysts, such as alkali metal compounds and/ or alkaline earth metal compounds, to the melt polycarbonate oligomer at a later stage of the melt polycondensation process, preferably after the oligomer has reached an average molecular weight of between about 3,000 and 30,000 g/mole, a unique branched polycarbonate composition is formed that has improved properties. It is believed that the addition of the branch-inducing catalysts at the later stages of the process produces a branched polycarbonate composition having longer chains between the branching points, and thus a new composition is produced. The invention also relates to various applications of the branched polycarbonate composition.