Conductive polymer compositions containing perhydrotriphenylene

• US 6,396,384 B1
• Filed: 10/10/2000
• Issued: 05/28/2002
• Est. Priority Date: 10/10/2000
• Status: Expired due to Term

• Current Assignee: Therm-O-Disc Incorporated (Emerson Electric Company)
• Original Assignee: Therm-O-Disc Incorporated (Emerson Electric Company)
• Inventors: Amadio, Blase S., Blok, Edward J.
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US09/685,371
• Time in Patent Office: 595 Days
• Field of Search: 338/22 R,22 SD 252/510,511
• US Class Current: 338/22.00R
• CPC Class Codes: H01C 7/028 consisting of organic substances

Abstract

The invention provides polymeric PTC compositions and electrical PTC devices with high voltage capability and high switch temperatures. The polymeric PTC composition specifically includes perhydrotriphenylene as an organic polymer component which, when blended with a crystalline or semi-crystalline organic polymer component such as polyethylene, gives rise to a composition having a melting point, Tm of up to about 181° C.

Claims

1. A polymeric PTC composition comprising an organic polymer component including perhydrotriphenylene, a conductive filler and an inert filler.

2. The composition of claim 1, wherein the organic polymer component includes a blend of perhydrotriphenylene and at least one crystalline or semi-crystalline polymer.

3. The composition of claim 2 wherein said at least one crystalline or semi-crystalline polymer is selected from the group consisting essentially of high molecular weight polyethylenes, low molecular weight polyethylenes, cis-1,4-polybutadiene, trans-1,4-polybutadiene, polyoxyethylene glycol, m-heptane, palmitic acid, stearic acid, undeilenic acid, adipic acid, azelaic acid and cetyl alcohol.

4. The composition of claim 2 wherein said blend includes a weight ratio of between about 50:

1 to about 1;

50 perhydrotriphenylene to said at least one crystalline or semi-crystalline polymer.

5. The composition of claim 2 wherein the blend has a melting point, T_m of up to about 181°

C.

6. The composition of claim 2 wherein the melting point, T_m of the blend is at least 10°

C. higher than the melting point, T_m of either of said perhydrotriphenylene or said crystalline or semi-crystalline polymer.

7. The composition of claim 1 wherein the second polymer has a melting temperature T_m of about 100°

C. to about 250°

C.

8. The composition of claim 1, having a resistivity at 25°

C. of 100 Ω

cm or less.

9. The composition of claim 1 wherein said inert filler is present in an amount of between about 0.25 phr to 100.0 phr.

10. The composition of claim 1 wherein said inert filler is present in an amount of between about 0.5 phr to 15.0 phr.

11. The composition of claim 1 wherein the conductive filler is selected from the group consisting of carbon black, graphite, metal particles, and mixtures thereof.

12. The composition of claim 10 wherein the metal particles are selected from the group consisting of nickel particles, silver flakes, or particles of tungsten, molybdenum, gold, platinum, iron, aluminum, copper, tantalum, zinc, cobalt, chromium, lead, titanium, tin alloys, and mixtures thereof.

14. The composition of claim 1 wherein the antioxidant comprises a phenol or an aromatic amine.

15. The composition of claim 14, wherein the antioxidant is selected from the group consisting of N,N′

-1,6-hexanediylbis (3,5-bis (1,1-dimethylethyl)-4-hydroxy-benzene) propanamide, (N-stearoyl-4-aminophenol, N-lauroyl-4-aminophenol, polymerized 1,2-dihydro-2,2,4-trimethyl quinoline, and mixtures thereof.

16. The composition of claim 1 wherein said conductive filler is present in an amount of between about 15.0 phr to 250.0 phr.

17. The composition of claim 1 wherein said conductive filler is present in an amount of between about 60.0 phr to 180.0 phr.

18. The composition of claim 1, wherein the polymeric PTC composition is crosslinked with the aid of a chemical agent or by irradiation.

19. The composition of claim 1 further comprising at least one additive selected from the group consisting of inert fillers, flame retardants, stabilizers, antioxidants, antiozonants, accelerators, pigments, foaming agents, crosslinking agents and dispersing agents.

13. The composition of claim I wherein the inorganic stabilizers are selected from the group consisting of magnesium oxide, zinc oxide, aluminum oxide, titanium oxide, calcium carbonate, magnesium carbonate, alumina trihydrate, magnesium hydroxide, and mixtures thereof.

20. An electrical device which exhibits PTC behavior, comprising:

(a) a conductive polymeric composition that comprises an organic polymer component including perhydrotripheneylene and a conductive filler, the composition having a resistivity at 25°

C. of 100 Ω

cm or less and a resistivity at its switching temperature that is at least 10³ times the resistivity at 25°

C.; and

(b) at least two electrodes which are in electrical contact with the conductive polymeric composition to allow a DC or an AC current to pass through the composition under an applied voltage, wherein the device has a resistance at 25°

C. of 500 mΩ

or less with a desirable design geometry.

21. The device of claim 20 wherein the device has a resistance at 25°

C. of about 5.0 mΩ

to about 400 mΩ

.

22. The device of claim 21 wherein the device has a resistance at 25°

C. of about 10 mΩ

to about 100 mΩ

.

23. The device of claim 20 wherein the organic polymer component includes a blend of perhydrotriphenylene and at least one crystalline or semi-crystalline polymer.

24. The composition of claim 20 wherein said blend includes a weight ratio of between about 50:

1 to about 1;

50 perhydrotriphenylene to said at least one crystalline or semi-crystalline polymer.

25. The composition of claim 20 wherein said at least one crystalline or semi-crystalline polymer is selected from the group consisting essentially of high molecular weight polyethylenes, low molecular weight polyethylenes, cis-1,4-polybutadiene, trans-1,4-polybutadiene, polyoxyethylene glycol, m-heptane, palmitic acid, stearic acid, undeilenic acid, adipic acid, azelaic acid and cetyl alcohol.

26. The composition of claim 23 wherein the second polymer has a melting point T_m of up to about 181°

C.

27. The composition of claim 22 wherein the crystalline or semi-crystalline polymer has a melting temperature T_m of about 100°

C. to about 250°

C.

28. The composition of claim 23 wherein the melting point, T_m of the blend is at least 10°

C. higher than the melting point, T_m of either of said perhydrotriphenylene or said crystalline or semi-crystalline polymers.

29. The composition of claim 20 wherein said inert filler is present in an amount of between about 0.25 phr to 100.0 phr.

30. The composition of claim 20 wherein said inert filler is present in an amount of between about 0.5 phr to 15.0 phr.

31. The composition of claim 20 wherein the conductive filler is selected from the group consisting of carbon black, graphite, metal particles, and mixtures thereof.

32. The composition of claim 29 wherein the metal particles are selected from the group consisting of nickel particles, silver flakes, or particles of tungsten, molybdenum, gold, platinum, iron, aluminum, copper, tantalum, zinc, cobalt, chromium, lead, titanium, tin alloys, and mixtures thereof.

33. The composition of claim 20 wherein the inorganic stabilizers are selected from the group consisting of magnesium oxide, zinc oxide, aluminum oxide, titanium oxide, calcium carbonate, magnesium carbonate, alumina trihydrate, magnesium hydroxide, and mixtures thereof.

34. The composition of claim 20, wherein the antioxidant is selected from the group consisting of N,N′

-1,6-hexanediylbis (3,5-bis (1,1-dimethylethyl)-4-hydroxy-benzene) propanamide, (N-stearoyl-4-aminophenol, N-lauroyl-4-aminophenol, polymerized 1,2-dihydro-2,2,4-trimethyl quinoline, and mixtures thereof.

35. The composition of claim 20 wherein said conductive filler is present in an amount of between about 15.0 phr to 250.0 phr.

36. The composition of claim 20 wherein said conductive filler is present in an amount of between about 60.0 phr to 180.0 phr.

37. The composition of claim 20 wherein the polymeric PTC composition is crosslinked with the aid of a chemical agent or by irradiation.

38. The composition of claim 20 further comprising at least one additive selected from the group consisting of inert fillers, flame retardants, stabilizers, antioxidants, antiozonants, accelerators, pigments, foaming agents, crosslinking agents and dispersing agents.