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Conductive polyester/polycarbonate blends, methods for preparation thereof, and articles derived therefrom

Imported: 24 Feb '17 | Published: 06 Jan '04

Bimal R. Patel, Estelle Cheret

USPTO - Utility Patents

Abstract

A conductive thermoplastic composition includes a polycarbonate, a polyester, a conductive filler, an impact modifier, a transesterification quench, and glass fibers. The composition exhibits high strength and stiffness and is especially suitable for molding rigid, electrostatically painted automobile parts.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a transmission electron micrograph of the sample corresponding to Example 2. The micrograph shows two co-continuous phases. The dark gray areas correspond to a continuous amorphous polycarbonate phase; the white ovoids within the dark gray areas correspond to the core-shell impact modifier, which has a domain size diameter of about 0.4 micron; the lighter gray areas correspond to a continuous poly(ethylene terephthalate) phase; and the small black specks within the lighter gray areas correspond to particles of conductive carbon black.

Claims

1. A conductive thermoplastic composition, comprising, based on the total weight of the composition:

wherein the composition comprises a first continuous phase comprising polyester, and wherein at least 50% of the conductive filler is disposed in the continuous phase comprising polyester.

2. The composition of claim 1, wherein the polycarbonate is synthesized from at least one dihydric phenol selected from the group consisting of 1,1-bis(4-hydroxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane; 2,2-bis(4-hydroxyphenyl)propane; 2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl)octane; 1,1-bis(4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)-n-butane; bis(4-hydroxyphenyl)phenylmethane; 2,2-bis(4-hydroxy-1-methylphenyl)propane; 1,1-bis(4-hydroxy-t-butylphenyl)propane; 2,2-bis(4-hydroxy-3-bromophenyl) propane; 1,1-bis(4-hydroxyphenyl)cyclopentane; and 1,1-bis(4-hydroxyphenyl)cyclohexane.

3. The composition of claim 1, wherein the polyester comprises repeating units of the formula

wherein n is 2 to 6, and R is a C

6-C

20 aryl radical.

4. The composition of claim 1, wherein the polyester comprises poly(ethylene terephthalate).

5. The composition of claim 1, wherein the conductive filler comprises conductive carbon black, vapor grown carbon fibers, or a mixture thereof.

6. The composition of claim 1, wherein the conductive filler comprises vapor grown carbon fibers having an average diameter of about 3.5 to about 70 nanometers.

7. The composition of claim 1, wherein the glass fibers have an average diameter of about 1 to about 50 micrometers.

8. The composition of claim 1, wherein the transesterification quencher is selected from the group consisting of mono-, di-, and tri-hydrogen phosphites and their metal salts; mono-, di-, and tri-hydrogen phosphates and their metal salts; mono- and di-hydrogen phosphonates and their metal salts; pyrophosphates and their metal salts; silyl phosphates; and mixtures comprising at least one of the foregoing quenchers.

9. The composition of claim 8, wherein the transesterification quencher comprises phosphorous acid.

10. The composition of claim 1, wherein the impact modifier is selected from the group consisting of core-shell polymers, olefin acrylates, olefin diene terpolymers, rubber polymers and copolymers, styrene-containing polymers, organic silicone rubbers, elastomeric fluorohydrocarbons, elastomeric polyesters, and random block polysiloxane-polycarbonate copolymers.

11. The composition of claim 1, wherein the impact modifier is selected from the group consisting of core-shell copolymers comprising a core of poly(butyl acrylate) and a shell of poly(methyl methacrylate); styrene-ethylene-butadiene copolymers; and methacrylate-butadiene-styrene copolymers.

12. The composition of claim 1, further comprising about 0.1 to about 20 weight percent of a polyester ionomer which is the polycondensation product of (1) an aromatic dicarboxylic acid or its ester-forming derivative; (2) a diol compound or its ester-forming derivative; and (3) an ester-forming compound containing an ionic sulfonate group.

13. The composition of claim 12, wherein the polyester ionomer comprises about 0.1 to about 50 mole percent of units derived from the ester-forming compound containing an ionic sulfonate group, based on the sum of units derived from the ester-forming compound containing an ionic sulfonate group and units derived from the aromatic dicarboxylic acid or its ester-forming derivative.

14. The composition of claim 1, further comprising at least one additive selected from the group consisting of stabilizers, mold release agents, processing aids, nucleating agents, UV blockers, and antioxidants.

15. The composition of claim 1, wherein the composition after molding has a heat distortion temperature at 264 psi according to ASTM D648 of at least 100° C.

16. The composition of claim 1, comprising a continuous phase comprising polycarbonate.

17. The composition of claim 16, wherein at least 50% of the impact modifier is disposed in the continuous phase comprising polycarbonate.

18. The composition of claim 1, wherein the composition comprises a second continuous phase comprising polycarbonate.

19. The composition of claim 1, wherein the composition after molding has a surface resistivity less than about 1000 megaohms.

20. A conductive thermoplastic composition, comprising, based on the total weight of the composition:

wherein the composition comprises a first continuous phase comprising polyester, and wherein at least 50% of the conductive filler is disposed in the continuous phase comprising polyester.

21. A method of preparing a conductive thermoplastic composition, comprising:

22. A molded article comprising the composition of claim 1.

23. An automobile body panel comprising the composition of claim 1.