Preparation of branched poly(alkylene terephthalates)

Claim 3

A process as defined in claim 1 wherein said poly(alkylene terephthalate) is poly(1,4-butylene terephthalate).

Claim 4

A process as defined in claim 1 wherein said mixed poly(alkylene terephthalate) comprises poly(ethylene terephthalate) and poly(1,4-butylene terephthalate).

Claim 5

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

Claim 6

A process as defined in claim 4 wherein heating step (b) is carried out between 180° and 210° C.

Claim 7

A process as defined in claim 5 wherein heating step (b) is carried out between 190° and 210° C.

Claim 8

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

Claim 9

A process as defined in claim 1 wherein the branching component is a polyol.

Claim 10

A process as defined in claim 8 wherein the branching component is trimethylolethane.

Claim 11

A process as defined in claim 8 wherein said branching component is pentaerythritol.

Claim 12

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

Claim 13

A process as defined in claim 11 wherein said branching component is trimethyl trimesate.

Claim 14

A solid state process for the preparation of a high melt viscosity branched copolyester consisting essentially of poly(1,4-butylene terephthalate) or of a mixture of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) 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 or mixture of polyesters having an intrinsic viscosity of greater than about 1.1 dl./g., measured as a solution in a 60:40 mixture of phenol and tetrachloroethane at 30° C., said process comprising: (a) intimately blending a normally solid poly(1,4-butylene terephthalate) or a mixture of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) having an intrinsic viscosity of from about 0.5 to about 1.05 dl./g., with said branching component and transforming the intimate blend into a solid, particulate state; and (b) heating the particles of said solid polyester-branching component blend in the presence of an inert gas at a temperature of about 150° C. and below the melting point thereof until the desired degree of increase in intrinsic viscosity is obtained.

Claim 15

A solid state process for the preparation of a high melt viscosity branched copolyester consisting essentially of poly(1,4-butylene terephthalate) or of a mixture of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) 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 or mixture of polyesters having an intrinsic viscosity of greater than about 1.1 dl./g., measured as a solution in a 60:40 mixture of phenol and tetrachloroethane at 30° C., said process comprising: (a) intimately blending a normally solid poly(1,4-butylene terephthalate) or a mixture of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) having an intrinsic viscosity of from about 0.5 to about 1.05 dl./g., with said branching component and transforming the intimate blend into a solid, particulate state; and (b) heating the particles of said solid polyester-branching component blend in the presence of an inert gas at a temperature of about 150° C. and below the melting point thereof until the desired degree of increase in intrinsic viscosity is obtained.

Claim 16

A process as defined in claim 13 wherein the branching component comprises 0.15 percent by weight of pentaerythritol, based on the weight of poly(1,4-butylene terephthalate) or mixture of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) and step (b) is carried out at a temperature range of 190° to 210° C. until the intrinsic viscosity has increased to at least 1.1 dl./g.