Conductive polymer composition

[54] CONDUCTIVE POLYMER COMPOSITION

[75] Inventors: Daniel Chandler, Menlo Park; Nelson H. Thein, Union City; Edward F. Chu, Sunnyvale, all of Calif.

[73] Assignee: Raychem Corporation, Menlo Park, Calif.

[21] Appl. No.: 894,119
[22] Filed: Jun. 5,1992

[51] Int. CL« H01B 1/00; H01B 1/14;

H01B 1/16

[52] U.S. CI 252/513; 252/512;

252/518; 252/519

[58] Field of Search 252/512, 513, 518, 519

[56] References Cited

U.S. PATENT DOCUMENTS

2,795,680 6/1957 Peck 201/63

2,825,702 3/1958 Silversher 252/503

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3,278,455 10/1966 Feather 252/512

3,412,043 11/1968 Gilliland 252/514

3,571,777 3/1971 Tully 338/20

3,597,720 8/1971 Burgess 338/202

3,666,689 5/1972 Groszek 252/512

3,686,139 8/1972 Lubin 252/511

3,976,600 8/1976 Meyer 252/511

3,983,075 9/1976 Marshall et al 252/511

4,237,441 12/1980 van Konynenburg et al. ... 338/22 R

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4,388,607 6/1983 Toy et al 338/22 SD

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4,534,889 8/1985 van Konynenburg et al 252/511

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4.591.700 5/1986 Sopory 219/505

4,610,808 9/1986 Kleiner 252/520

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4,685,025 8/1987 Carlomagno 361/106

4,689,475 8/1987 Matthiesen 219/553

4,724,417 2/1988 Au et al 338/22 R

4,726,991 2/1988 Hyatt et al 252/507

4.732.701 3/1988 Nishii et al 252/516

4,774,024 9/1988 Deep et al 252/511

4,780,598 10/1988 Fahey et al 219/511

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4,935,156 6/1990 van Konynenburg et al 219/553

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5,115,077 5/1992 Matsuo et al 528/125

FOREIGN PATENT DOCUMENTS

922039 2/1973 Canada 400/72

1449321 7/1966 France .

50-748 1/1975 Japan C08L 101/00

51-59947 5/1976 Japan C08K 3/00

53-28261 3/1978 Japan H01B 5/16

1-260711 10/1989 Japan H01B 1/22

760499 10/1956 United Kingdom .

1369210 10/1974 United Kingdom C08G 43/00

1444722 8/1976 United Kingdom H05B 3/24

2000518 6/1977 United Kingdom C09D 5/24

1602372 11/1981 United Kingdom C08L 83/04

OTHER PUBLICATIONS

Search Report, PTC/US93/05335, Sep. 28, 1993. ASTM B329-85, "Standard Test Method for Apparent Density of Powders of Refractory Metals and Compounds by the Scott Volumeter" 1985.

(List continued on next page.)

Primary Examiner—Paul Lieberman

Assistant Examiner—M. Kopec

Attorney, Agent, or Firm—Herbert G. Burkard;

Marguerite E. Gerstner; Timothy H. P. Richardson

[57] ABSTRACT

A conductive polymer composition which has low resistivity and good electrical stability. In one aspect the composition comprises a nonconductive filler which is a dehydrated metal oxide. In another aspect the composition comprises a conductive filler which is metal particles in which the bulk density is less than 0.15 times the true density. Compositions of the invention are particularly useful for circuit protection devices.

14 Claims, 2 Drawing Sheets

OTHER PUBLICATIONS "Electrical Conductivity and Heat Expansion to Filled Polymers", A. D. Stadnik, Izvestiya Vysshikh Uchebnikh Zavedeniy, Khimii, I. Khimicheskoy Tekhnologii, vol. 21, No. 7, pp. 1078-79 (1978). "INCO Nickel Powders, Porperties and Applications", International Nickel, Inc., Dec, 1983. "Investigation of Current-Interruption by Metal-filled Epoxy Resin", S. Littlewood and B. F. N. Briggs, J.

Phys. D: Appl. Phys., vol. 11, pp. 1457-62 (1978). "Solid State Bistable Power Switch Study", Herman Shulman & John Bartko, NASA Report N68-35634, Aug. 1968.

"Solid State Bistable Power Switch", NASA Technical Brief 70-10383 (1970).

"Solid-State Recoverable Fuse Functions as Circuit Breaker", Edward F. Thomas, NASA Technical Brief 66-10691. 1978.