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US 5,378,407 AGranted
Conductive polymer composition
AssigneeRaychem Corporation
InventorsDaniel Chandler, Nelson H. Thein, Edward F. Chu
Life of this patent
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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.
Claims14
A conductive polymer composition which comprises
- (1) 40 to 70% by volume crystalline organic polymer which comprises a polyolefin, a copolymer of at least one olefin and at least one monomer copolymerisable therewith, or a fluoropolymer;
- (2) 25 to 40% by volume conductive particulate filler which is dispersed in the organic polymer and which comprises particles which
- (a) comprise nickel,
- (b) have a shape such that particles having the same shape and consisting of the same metal have a bulk density DB as measured by ASTM B329 which is (i) less than 1.3 g/cm.sup.3 and (ii) q times the true density DT of the metal, where q is less than 0.15,
- (c) have a filamentary structure;
- and
- (3) a nonconductive filler which is obtained substantially complete dehydration of a hydrate of a metal oxide.
4 more elements
A PTC conductive polymer composition which consists essentially of
- (1) 40 to 75% by volume crystalline organic polymer, which comprises a polyolefin, a copolymer of at least one olefin and at least one monomer copolymerisable therewith, or a fluoropolymer;
- (2) 25 to 40% by volume nickel particles which have a filamentary structure,
- (3) 1 to 20% by volume X-alumina, and
- (4) 0 to 5% by volume coupling agent.
1 more element
Dependencies are inferred from the claim text.