Polycarbodiimide modification of polyesters for extrusion applications

Claim 2

A process for preparing a polycarbodiimide modified thermoplastic polyester of increased melt strength and intrinsic viscosity as well as improved die swell and shear sensitivity, which process comprises incorporating into the structure of a thermoplastic saturated polyester, having at least one carboxyl end group, at least one polycarbodiimide which polycarbodiimide both (a) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule, by reacting the carboxyl end group of the polyester, at a temperature not less than the melting point of the polyester and below the decomposition temperature of the polyester and the polycarbodiimide, with the carbodiimide groups of the polycarbodiimide, wherein the polycarbodiimide modified thermoplastic polyester has a melt strength of less than about 2.0 at 235° C, less than about 10 micro equivalents of carboxyl end groups per gram of polyester, an intrinsic viscosity of about 1.1 to about 2.5, and is useful in extrusion applications.

Claim 3

The process of claim 1 wherein there is employed from about 0.5 to about 5% polycarbodiimide and from about 95 to about 99.5% thermoplastic polyester by weight of the total reaction mixture.

Claim 4

The process of claim 2 wherein said reaction is carried out at a temperature of from about 200° to about 350° C and at substantially atmospheric pressure.

Claim 5

The process of claim 3 wherein said polycarbodiimide may be selected from the group consisting essentially of poly(tolyl carbodiimide), poly(4,4'-diphenylmethane carbodiimide), poly(3,3'-dimethyl-4,4'-biphenylene carbodiimide), poly(p-phenylene carbodiimide), poly(m-phenylene carbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethane carbodiimide) and mixtures thereof.

Claim 6

A process for preparing a polycarbodiimide modified thermoplastic polyester of increased melt strength and intrinsic viscosity as well as improved die swell and shear sensitivity, which process comprises incorporating into the structure of a thermoplastic saturated polyester, having at least one carboxyl end group and which is selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, at least one polycarbodiimide which polycarbodiimide both (a) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule, by reacting the carboxyl end groups of said polyester, at a temperature not less than the melting point of the polyester and below the decomposition temperature of the polyester and the polycarbodiimide with the carbodiimide groups of the polycarbodiimide, wherein the polycarbodiimide modified thermoplastic polyester has a melt strength of less than about 2.0 at 235° C, less than about 10 micro equivalents of carboxyl end groups per gram of polyester, an intrinsic viscosity of about 1.1 to about 2.5, and is useful in extrusion applications.

Claim 7

A process for preparing a polycarbodiimide modified thermoplastic polyester of increased melt strength and intrinsic viscosity as well as improved die swell and shear sensitivity, which process comprises incorporating into the structure of a thermoplastic saturated polyester, having at least one carboxyl end group and which is selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, at least one polycarbodiimide which polycarbodiimide both (a) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule, by reacting the carboxyl end groups of said polyester, at a temperature not less than the melting point of the polyester and below the decomposition temperature of the polyester and the polycarbodiimide with the carbodiimide groups of the polycarbodiimide, wherein the polycarbodiimide modified thermoplastic polyester has a melt strength of less than about 2.0 at 235° C, less than about 10 micro equivalents of carboxyl end groups per gram of polyester, an intrinsic viscosity of about 1.1 to about 2.5, and is useful in extrusion applications.

Claim 8

The process of claim 5 wherein there is employed from about 1.5 to about 4% polycarbodiimide and from about 96 to about 98.5% thermoplastic polyester by weight of the total reaction mixture, and wherein said reaction is carried out at a temperature of from about 225° to about 290° C and at substantially atmospheric pressure.

Claim 9

A process for preparing a polycarbodiimide modified thermoplastic polyester of increased melt strength and intrinsic viscosity as well as improved die swell and shear sensitivity, which process comprises incorporating into the structure of a thermoplastic saturated polyester having at least one carboxyl end group and which is selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, from about 1.5 to about 3% by total weight of reactants, of at least one polycarbodiimide selected from the group consisting of poly(tolyl carbodiimide), poly(4,4'-diphenylmethane carbodiimide), poly(3,3'-dimethyl-4,4'-biphenylene carbodiimide), poly(p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethane carbodiimide) and mixtures thereof by reacting the carboxyl end group of the polyester, at a temperature of from about 235° to about 265° C and at substantially atmospheric pressure, with the carbodiimide groups of the polycarbodiimide, wherein the polycarbodiimide modified thermoplastic polyester has a melt strength of less than about 2.0 at 235° C, less than about 10 micro equivalents of carboxyl end groups per gram of polyester, an intrinsic viscosity of about 1.1 to about 2.5 and is useful in extrusion applications.

Claim 10

A process for preparing a polycarbodiimide modified thermoplastic polyester of increased melt strength and intrinsic viscosity as well as improved die swell and shear sensitivity, which process comprises incorporating into the structure of a thermoplastic saturated polyester having at least one carboxyl end group and which is selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, from about 1.5 to about 3% by total weight of reactants, of at least one polycarbodiimide selected from the group consisting of poly(tolyl carbodiimide), poly(4,4'-diphenylmethane carbodiimide), poly(3,3'-dimethyl-4,4'-biphenylene carbodiimide), poly(p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethane carbodiimide) and mixtures thereof by reacting the carboxyl end group of the polyester, at a temperature of from about 235° to about 265° C and at substantially atmospheric pressure, with the carbodiimide groups of the polycarbodiimide, wherein the polycarbodiimide modified thermoplastic polyester has a melt strength of less than about 2.0 at 235° C, less than about 10 micro equivalents of carboxyl end groups per gram of polyester, an intrinsic viscosity of about 1.1 to about 2.5 and is useful in extrusion applications.

Claim 11

A polycarbodiimide modified thermoplastic polyester having a melt strength ratio of T 1 /T 2 of less than about 2 wherein said polycarbodiimide modified thermoplastic polyester comprises the reaction product of (a) a thermoplastic saturated polyester, and (b) a polycarbodiimide which both (1) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (2) contains at least three carbodiimide units per polycarbodiimide molecule which polycarbodiimide modified thermoplastic polyester is useful in extrusion applications.

Claim 12

A polycarbodiimide modified thermoplastic polyester having a melt strength ratio of T 1 /T 2 of less than about 2 wherein said polycarbodiimide modified thermoplastic polyester comprises the reaction product of (a) a thermoplastic saturated polyester, and (b) a polycarbodiimide which both (1) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (2) contains at least three carbodiimide units per polycarbodiimide molecule which polycarbodiimide modified thermoplastic polyester is useful in extrusion applications.

Claim 13

The polycarbodiimide modified thermoplastic polyester of claim 8 wherein said polycarbodiimide is selected from the group consisting essentially of poly (tolyl carbodiimide), poly(4,4'-diphenylmethane carbodiimide), poly(3,3'-dimethyl-4,4'-biphenylene carbodiimide), poly(p-phenylene carbodiimide), poly(m-phenylene carbodiimide), poly (3,3'-dimethyl-4,4'-diphenylmethane carbodiimide), and mixtures thereof.

Claim 14

The polycarbodiimide modified thermoplastic polyester of claim 9 wherein said polycarbodiimide modified thermoplastic polyester comprises from about 1 to about 5% polycarbodiimide and from about 95 to about 99% thermoplastic saturated polyester by weight of the total composition.

Claim 15

A polycarbodiimide modified thermoplastic polyester having a melt strength ratio of T 1 /T 2 of less than about 1.6, wherein said polycarbodiimide modified thermoplastic polyester comprises the reaction product of (a) from about 96 to about 98.5% thermoplastic saturated polyester selected from the group consisting essentially of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, and from about 1.5 to about 4% by weight of a polycarbodiimide selected from the group consisting of poly(tolyl carbodiimide), poly (4,4'-diphenylmethane carbodiimide), and mixtures thereof which polycarbodiimide modified thermoplastic polyester is useful in extrusion applications.

Claim 16

A polycarbodiimide modified thermoplastic polyester having a melt strength ratio of T 1 /T 2 of less than about 1.6, wherein said polycarbodiimide modified thermoplastic polyester comprises the reaction product of (a) from about 96 to about 98.5% thermoplastic saturated polyester selected from the group consisting essentially of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, and from about 1.5 to about 4% by weight of a polycarbodiimide selected from the group consisting of poly(tolyl carbodiimide), poly (4,4'-diphenylmethane carbodiimide), and mixtures thereof which polycarbodiimide modified thermoplastic polyester is useful in extrusion applications.

Claim 17

The polycarbodiimide modified thermoplastic polyester of claim 11 wherein said polycarbodiimide modified thermoplastic polyester comprises the reaction product of polybutylene terephthalate and poly (4,4'-diphenylmethane carbodiimide).

Claim 18

The polycarbodiimide modified thermoplastic polyester of claim 12 wherein said polycarbodiimide modified thermoplastic polyester comprises from about 1.5 to about 3% polycarbodiimide and from about 97 to about 98.5% thermoplastic saturated polyester by weight of the total composition.

Claim 19

An improved molding process which comprises forming the molten polycarbodiimide modified thermoplastic polyester of claim 8 into a desired article and cooling the molten polycarbodiimide modified thermoplastic polyester.