The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 02, 1980
Filed:
Dec. 01, 1978
Peter V van Konynenburg, Fremont, CA (US);
Andrew Au, Fremont, CA (US);
Chris Rauwendaal, Menlo Park, CA (US);
Alan J Gotcher, Saratoga, CA (US);
Raychem Corporation, Menlo Park, CA (US);
Abstract
Compositions which exhibit PTC behavior with a switching temperature (T.sub.s) above 0.degree. C., which have a resistivity at a temperature below T.sub.s of less than 7 ohm. cm, and which comprise a crystalline polymer and a particulate filler component which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area S in m.sup.2 /gram such that S/D is not more than 10. The composition preferably has a peak resistivity of at least 1000 ohm. cm and is electrically stable when aged at elevated temperature. The quantity ##EQU1## is preferably less than 1, especially less than 0.5. Shaped articles of such compositions are prepared by a process in which the carbon black is dispersed in the molten polymer and the dispersion is then melt-shaped, the total energy used in preparing and melt-shaping the dispersion being 1 to 300 hp. hr. ft.sup.-3, preferably 1 to 100 hp. hr. ft.sup.-3, especially 1 to 50 hp. hr. ft.sup.-3. The compositions are particularly useful in circuit protection devices.