Multicomponent polyester/polycarbonate blends with improved impact strength and processability

A thermoplastic molding composition comprising:

• (A) about 10 to about 90 weight percent of an aromatic polycarbonate of 4,4'isopropylidenediphenol having a relative viscosity of about 1.1 to about 1.5;
• (B) about 90 to about 10 weight percent of a poly(1,4-cyclohexylenedimethylene terephthalate) resin consisting essentially of repeat units from terephthalic acid and 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol, said resin having an inherent viscosity of about 0.4 to about 1.2 dl/g;
• (C) about 10 to about 90 weight percent of a copolyester comprising
• (1) a dicarboxylic acid component consisting essentially of repeat units from about 1 to about 50 mole percent isophthalic acid and from about 50 to about 99 mole percent terephthalic acid, and
• (2) a diol component consisting essentially of repeat units from 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol;
• and
• (D) about 0.05 to about 50 weight percent of copolymeric reaction products of (A), (B) and (C);
• it being understood that the combined weights of (A), (B), (C) and (D) total 100 percent.

A thermoplastic molding composition produced by mixing in the presence of an active esterification catalyst

• (A) about 10 to about 90 weight percent of an aromatic polycarbonate of 4,4'isopropylidenediphenol having a relative viscosity of about 1.1 to about 1.5;
• (B) about 90 to about 10 weight percent of a poly(1,4-cyclohexylenedimethylene terephthalate) resin consisting essentially of repeat units from terephthalic acid and 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol, said resin having an inherent viscosity of about 0.4 to about 1.2 dl/g;
• and
• (C) about 10 to about 90 weight percent of a copolyester comprising
• (1) a dicarboxylic acid component consisting essentially of repeat units from about 1 to about 50 mole percent isophthalic acid and from about 50 to about 99 mole percent terephthalic acid, and
• (2) a diol component consisting essentially of repeat units from 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol;
• under reaction conditions such that transesterification occurs to the extent that from about 0.05 to about 50 weight percent of the polyester moieties are chemically reacted with a polycarbonate moiety.

A process for injection molding a thermoplastic polyester comprising

• (I) substantially homogeneously blending
• (A) about 10 to about 90 weight percent of an aromatic polycarbonate of 4,4'isopropylidenediphenol having a relative viscosity of about 1.1 to about 1.5;
• (B) about 90 to about 10 weight percent of a poly(1,4-cyclohexylenedimethylene terephthalate) resin consisting essentially of repeat units from terephthalic acid and 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol, said resin having an inherent viscosity of about 0.4 to about 1.2 dl/g;
• and
• (C) about 10 to about 90 weight percent of a copolyester comprising
• (1) a dicarboxylic acid component consisting essentially of repeat units from about 1 to about 50 mole percent isophthalic acid and from about 50 to about 99 mole percent terephthalic acid, and
• (2) a diol component consisting essentially of repeat units from 1,4-cyclohexanedimethanol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol;
• it being understood that the combined weights of (A), (B) and (C) total 100 percent;
• and
• (II) injection molding said blend at melt temperatures of about 250.degree. C. to about 325.degree. C. into molds held at a temperature of about 10.degree. C. to about 90.degree. C.