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US 5,880,668 AGranted
Electrical devices having improved PTC polymeric compositions
AssigneeLittelfuse, Inc.
InventorTom J. Hall
Life of this patent
Estimating the term…
Abstract
Circuit protection devices comprising PTC elements and circuits containing such devices. The PTC element includes a crystalline conductive polymer composition comprising a conductive particulate filler grafted to a modified polyolefin. The modified polyolefin comprises a polyolefin having a carboxylic acid or a carboxylic acid derivative grafted thereto. The conductive particulate filler is grafted via an esterification reaction to the modified polyolefin.
Claims12
An electrical device comprising:
- (a) a PTC element having a modified polyolefin component comprised of a polyolefin having a carboxylic acid or a carboxylic acid derivative drafted thereto, grafted to a conductive particulate filler component;
- and
- (b) two electrodes, each electrode being connectable to a source of power, and when so connected, causing current to flow through the PTC element.
An electrical device comprising:
- (a) a PTC element having a modified polyolefin component grafted to a conductive particulate filler component, the modified polyolefin component comprised of about 90-99% by weight polyethylene and about 1-10% by weight carboxylic acid or a carboxylic acid derivative, the PTC element having a resistivity at 25.degree. C. of less than 5 ohm cm and a peak resistivity at a temperature greater than 25.degree. C. of at least 1,000 ohm cm;
- and
- (b) two electrodes, each electrode being connectable to a source of power, and when so connected, causing current to flow through the PTC element, the electrical device having a resistance, R.sub.int, at 25.degree. C. of less than 1 ohm.
An electrical device comprising:
- (a) a PTC element having a modified polyolefin component comprised of a polyolefin having a carboxylic acid or a carboxylic acid derivative drafted thereto, grafted to a conductive particulate filler component;
- and
- (b) two electrodes having a surface roughness, R.sub.a, less than 1 micron, each electrode being connectable to a source of power, and when so connected, causing current to flow through the PTC element.
Dependencies are inferred from the claim text.