Process for Production of Copolycarbonates with Reduced Color

A molded article formed from copolycarbonate with improved color prepared by the method comprising the steps of,

• i. preparing a molten reaction mixture comprising a first dihydroxy aromatic compound comprising monomer residue (a), a second dihydroxy aromatic compound comprising monomer residue (b), and a carbonate source,
• wherein monomer residue (a) is a quinone structure, or a structure capable of forming a quinone structure upon oxidation,
• wherein monomer residue (b) is a quinone structure, or a structure capable of forming a quinone structure upon oxidation different from monomer residue (a) or is,
• where B is
• —O—, —CO—, —S—, —SO2—, a C6-C20 aromatic radical, or a C6-C20 cycloaliphatic radical;
• the groups R1 and R2 are independently a hydrogen atom, C1-C20 alkyl radical, C4-C20 cycloalkyl radical, or C4-C20 aryl radical;
• or R1 and R2 together form a C4-C20 cycloaliphatic ring which is optionally substituted by one or more C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl, C5-C20 cycloalkyl groups or a combination thereof, R3 is a divalent hydrocarbylene group, and R4 and R5 are independently a hydrogen atom, halogen atom, nitro group, cyano group, C1-C20 alkyl radical C4-C20 cycloalkyl radical, or C6-C20 aryl radical and p and q are both integers from 0 to 4,
• ii. selecting a catalyst introduction strategy sufficient to result in a product copolycarbonate with improved color, wherein the catalyst introduction strategy is selected from the group consisting of,
• 1. introducing a polymerization catalyst to the molten reaction mixture after monomer residues (a), monomer residues (b), and carbonate source are melted and prior to substantial polymerization,
• 2. introducing a polymerization catalyst to the reaction mixture or monomer residues prior to melting with the proviso that residence time of the process from the start of melting until substantial polymerization has occurred is less than 4 hours, and
• 3. or a combination thereof,
• wherein the polymerization catalyst is an inorganic catalyst, an organic catalyst, or both inorganic and organic catalyst which may be introduced separately or together,
• iii. introducing the catalyst according to the selected catalyst introduction strategy,
• iv. introducing the reaction mixture to a series of process units,
• v. allowing the reaction mixture to polymerize in the series of process units thereby forming copolycarbonate, wherein the copolycarbonate has improved color as compared to a copolycarbonate formed in a melt process without the steps of selecting a catalyst introduction strategy and introducing catalyst according to the selected strategy, and
• vi. forming a molded article from the copolycarbonate.

A method for making a molded article formed from copolycarbonate with improved color prepared by the method comprising the steps of,

• i. preparing a molten reaction mixture comprising a first dihydroxy aromatic compound comprising monomer residue (a), a second dihydroxy aromatic compound comprising monomer residue (b), and a carbonate source,
• wherein monomer residue (a) is a quinone structure, or a structure capable of forming a quinone structure upon oxidation,
• wherein monomer residue (b) is a quinone structure, or a structure capable of forming a quinone structure upon oxidation different from monomer residue (a) or is,
• where B is
• —O—, —CO—, —S—, —SO2—, a C6-C20 aromatic radical, or a C6-C20 cycloaliphatic radical;
• the groups R1 and R2 are independently a hydrogen atom, C1-C20 alkyl radical, C4-C20 cycloalkyl radical, or C4-C20 aryl radical;
• or R1 and R2 together form a C4-C20 cycloaliphatic ring which is optionally substituted by one or more C1-C20 alkyl, C6-C20 aryl, C5-C21, aralkyl, C5-C20 cycloalkyl groups or a combination thereof, R3 is a divalent hydrocarbylene group, and R4 and R5 are independently a hydrogen atom, halogen atom, nitro group, cyano group, C1-C20 alkyl radical C4-C20 cycloalkyl radical, or C6-C20 aryl radical and p and q are both integers from 0 to 4,
• ii. selecting a catalyst introduction strategy sufficient to result in a product copolycarbonate with improved color, wherein the catalyst introduction strategy is selected from the group consisting of,
• 1. introducing a polymerization catalyst to the molten reaction mixture after monomer residues (a), monomer residues (b), and carbonate source are melted and prior to substantial polymerization,
• 2. introducing a polymerization catalyst to the reaction mixture or monomer residues prior to melting with the proviso that residence time of the process from the start of melting until substantial polymerization has occurred is less than 4 hours, and
• 3. or a combination thereof,
• wherein the polymerization catalyst is an inorganic catalyst, an organic catalyst, or both inorganic and organic catalyst which may be introduced separately or together,
• iii. introducing the catalyst according to the selected catalyst introduction strategy,
• iv. introducing the reaction mixture to a series of process units,
• v. allowing the reaction mixture to polymerize in the series of process units thereby forming copolycarbonate, wherein the copolycarbonate has improved color as compared to a copolycarbonate formed in a melt process without the steps of selecting a catalyst introduction strategy and introducing catalyst according to the selected strategy, and
• vi. forming a molded article from the copolycarbonate.