Raychem Limited

O James Straley

Ravinder K Oswal

Jeff Shafe

Gordon McCarty

Amitkumar N Dharia

Bernadette A Trammell

A polymer thick film ink which exhibits PTC behavior comprising an organic polymer which is crystalline, an active solvent suitable for dissolving the polymer, and carbon black which has a pH of less than 4.0. The ink is particularly useful in producing electrical devices such as heaters and circuit protection devices.

Method of making an electrical device comprising a conductive polymer

Conductive polymer composition

Electrical devices with improved resistance stability comprise a PTC element comprising a conductive polymer and two electrodes. The conductive polymer composition comprises an organic crystalline polymer and carbon black with a pH of less than 5.0. Particularly preferred conductive polymer compositions comprise carbon blacks which have a pH of less than 5.0, a dry resistivity R.sub.CB and a particle size D in nanometers such that R.sub.CB /D is at most 0.1. Electrical devices of the invention include heaters and circuit protection devices.

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Redwood City, CA, United States of America

O James Straley