Thermally-conductive plastic articles having light reflecting surfaces

• US 20040251804A1
• Filed: 06/11/2003
• Published: 12/16/2004
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: Ticona Polymers, Inc. (Celanese Corporation)
• Original Assignee: Cool Options, Inc.
• Inventors: Sagal, E. Mikhail, Miller, James, McCullough, Kevin
• Granted Patent: US 7,235,918 B2
• Time in Patent Office: Days
• US Class Current: 313/113
• CPC Class Codes: B29C 45/0013 using fillers dispersed in the moulding material, e.g. metal particles
• CPC Class Codes: B29C 70/88 characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced
• CPC Class Codes: B29K 2995/0013 Conductive
• CPC Class Codes: B29K 2995/003 Reflective
• CPC Class Codes: B29L 2011/0083 Reflectors
• CPC Class Codes: C08K 3/04 Carbon
• CPC Class Codes: F21S 41/37 characterised by their material, surface treatment or coatings
• CPC Class Codes: F21V 29/505 of reflectors
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: F21W 2103/00 Exterior vehicle lighting devices for signalling purposes
• CPC Class Codes: Y10T 428/1355 Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31507 Of polycarbonate

Abstract

A thermally-conductive polymer composition suitable for making molded reflector articles having light-reflecting surfaces is provided. The composition comprises: a) about 20% to about 80% by weight of a base polymer matrix such as polycarbonate; and b) about 20% to about 80% by weight of a thermally-conductive carbon material such as graphite. The composition can be used to make reflector articles such as housings for automotive tail lamps, head lamps, and other lighting fixtures. A method for manufacturing reflector articles is also provided.

Claims

1. A thermally-conductive polymer composition suitable for making reflector articles having light-reflecting surfaces, comprising:

a) about 20% to about 80% by weight of a base polymer matrix; and

b) about 20% to about 80% by weight of a thermally-conductive carbon material.

2. The composition of claim 1, wherein the polymer matrix comprises a thermoplastic polymer.

3. The composition of claim 2, wherein the thermoplastic polymer is selected from the group consisting of polycarbonates, polyethylene, polypropylene, acrylics, vinyls, fluorocarbons, polyamides, polyphenylene sulfide, and liquid crystal polymers.

4. The composition of claim 1, wherein the polymer matrix comprises a thermosetting polymer.

5. The composition of claim 4, wherein the thermosetting polymer is selected from the group consisting of elastomers, epoxies, polyesters, polyimides, and acrylonitriles.

6. The composition of claim 1, wherein the thermally-conductive carbon material is in the form of particles.

7. The composition of claim 1, wherein the thermally-conductive carbon material is selected from the group consisting of graphite, carbon black, and carbon fibers.

8. The composition of claim 1, further comprising about 5 to about 30% by weight of a reinforcing material.

9. The composition of claim 8, wherein the reinforcing material is glass.

10. The composition of claim 1, further comprising an additive selected from the group consisting of antioxidants, plasticizers, stabilizers, dispersing agents, coloring agents, and mold-releasing agents.

11. The composition of claim 1, wherein the composition comprises about 74% by weight of polycarbonate, about 24% by weight of carbon graphite, and about 1% by weight of a mold-releasing agent.

12. The composition of claim 1, wherein the composition has a thermal conductivity of greater than 10 W/m°

K.

13. A molded reflector article having a light-reflecting surface, said article comprising:

a) about 20% to about 80% by weight of a base polymer matrix; and

b) about 20% to about 80% by weight of a thermally-conductive carbon material.

14. The molded reflector article of claim 13, wherein the article is in the form of a housing for an automotive tail lamp.

15. The molded reflector article of claim 13, wherein the article is in the form of a housing for an automotive head lamp.

16. The molded reflector article of claim 13, wherein the polymer matrix comprises a thermoplastic polymer.

17. The molded reflector article of claim 13, wherein the polymer matrix comprises a thermosetting polymer.

18. The molded reflector article of claim 13, wherein the polymer composition further comprises about 5% to about 30% by weight of a reinforcing material.

19. The molded reflector article of claim 13, wherein the polymer composition comprises about 74% by weight of polycarbonate, about 24% by weight of carbon graphite, and about 1% by weight of a mold-releasing agent.

20. A method of making a net-shape molded, thermally-conductive reflector article having a light-reflecting surface, comprising the steps of:

a) providing a molten polymer composition comprising;

i) about 20% to about 80% by weight of a base polymer matrix; and

ii) about 20% to about 80% by weight of a thermally-conductive carbon material;

b) injecting the molten composition into a mold to form a net-shape molded, thermally-conductive reflector article; and

c) removing the reflector article from the mold.

21. The method of claim 20, wherein the polymer matrix comprises a thermoplastic polymer.

22. The method of claim 20, wherein the thermoplastic polymer is selected from the group consisting of polycarbonates, polyethylene, polypropylene, acrylics, vinyls, fluorocarbons, polyamides, polyphenylene sulfide, and liquid crystal polymers.

23. The method of claim 20, wherein the polymer matrix comprises a thermosetting polymer.

24. The method of claim 20, wherein the thermosetting polymer is selected from the group consisting of elastomers, epoxies, polyesters, polyimides, and acrylonitriles.

25. The method of claim 20, wherein the thermally-conductive material is in the form of particles.

26. The method of claim 20, wherein the thermally-conductive carbon material is selected from the group consisting of graphite, carbon black, and carbon fibers.

27. The method of claim 20, wherein the polymer composition further comprises about 5% to about 30% by weight of a reinforcing material.

28. The method of claim 27, wherein the reinforcing material is glass.

29. The method of claim 20, wherein the polymer composition further comprises an additive selected from the group consisting of antioxidants, plasticizers, stabilizers, dispersing agents, coloring agents, and mold-releasing agents.

30. The method of claim 20, wherein the polymer composition comprises about 74% by weight of polycarbonate, about 24% by weight of carbon graphite, and about 1% by weight of mold-releasing agent.