Process for the solid state polymerization of branched poly(alkylene terephthalates) using aromatic polycarbonates

Claim 2

An improved process for the preparation of a high melt viscosity hydroxy terminated branched copolyester comprising alkylene terephthalate units and from 0.01 to 3 mole percent, based on the terephthalate units, of units of a branching component which contains at least three ester-forming groups, said branched polyester having a melt viscosity of greater than about 10,000 poises, said process comprising: (a) forming an intimate blend of a corresponding, normally solid branched copolyester having a melt viscosity of below 3,000 poises and from 0.1 to 5.0 percent by weight of an aromatic (poly-) or (copoly-)carbonate resin and transforming said blend into a solid particulate state; and (b) heating the particles of solid branched copolyester-aromatic (poly-) or (copoly-)carbonate blend at a temperature of at least 150° C. and below the melting point of said polyester in the presence of an inert gas until the desired degree of increase in melt viscosity is obtained.

Claim 3

A process as defined in claim 1 wherein heating step (b) is carried out between 150° and 210° C.

Claim 4

A process as defined in claim 2 wherein heating step (b) is carried out between 180° and 210° C.

Claim 5

A process as defined in claim 3 wherein heating step (b) is carried out between 190° and 210° C.

Claim 6

A process as defined in claim 1 wherein the inert gas in nitrogen.

Claim 7

A process as defined in claim 5 wherein the inert gas also includes vaporized butanediol-1,4.

Claim 8

A process as defined in claim 1 wherein the branching component which contains at least three ester-forming groups is a polyol.

Claim 9

A process as defined in claim 7 wherein the branching component is pentaerythritol.

Claim 10

A process as defined in claim 1 wherein the branching component is a tricarboxylic acid, a tetracarboxylic acid or a lower alkyl ester thereof.

Claim 11

A process as defined in claim 9 wherein said branching component is trimethyl trimesate.

Claim 12

A process as defined in claim 1 wherein said alkylene terephthalate units comprise 1,4-butylene terephthalate units.

Claim 13

A process as defined in claim 1 wherein said aromatic (poly-)carbonate resin comprises bisphenol-A polycarbonate.

Claim 14

A process as defined in claim 1 wherein said aromatic (copoly-)carbonate resin comprises bisphenol-A/tetrabromobisphenol-A (copoly-)carbonate.

Claim 15

A solid state process for the preparation of a high melt viscosity hydroxy terminated branched copolyester comprising 1,4-butylene terephthalate units and from 0.01 to 3 mole percent, based on the terephthalate units, of units of a branching component which contains at least three ester-forming groups, said polyester having a melt viscosity of greater than 15,000 poises, said process comprising: (a) forming an intimate blend of a corresponding, normally solid copolyester having a melt viscosity of below 3,000 poises and from about 0.5 to 2 percent by weight of a bisphenol-A (poly-)carbonate resin or a bisphenol-A/tetrabromobisphenol-A (copoly-)carbonate resin and transforming the blend into a solid, particulate state; and (b) heating the particles of said solid branched copolyester-aromatic (poly-) or (copoly-) carbonate blend in an inert atmosphere at a temperature of at least 150° C. and below the melting point of said polyester in the presence of an inert gas until the desired degree of increase in melt viscosity is obtained.

Claim 16

A solid state process for the preparation of a high melt viscosity hydroxy terminated branched copolyester comprising 1,4-butylene terephthalate units and from 0.01 to 3 mole percent, based on the terephthalate units, of units of a branching component which contains at least three ester-forming groups, said polyester having a melt viscosity of greater than 15,000 poises, said process comprising: (a) forming an intimate blend of a corresponding, normally solid copolyester having a melt viscosity of below 3,000 poises and from about 0.5 to 2 percent by weight of a bisphenol-A (poly-)carbonate resin or a bisphenol-A/tetrabromobisphenol-A (copoly-)carbonate resin and transforming the blend into a solid, particulate state; and (b) heating the particles of said solid branched copolyester-aromatic (poly-) or (copoly-) carbonate blend in an inert atmosphere at a temperature of at least 150° C. and below the melting point of said polyester in the presence of an inert gas until the desired degree of increase in melt viscosity is obtained.

Claim 17

A process as defined in claim 7 wherein the branching component is trimethylolpropane.