Devices comprising PTC conductive polymers
US4743321A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 1985 |
| Grant date | May 10, 1988 |
| Priority date | — |
| Expiry date | Oct 4, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S174/08
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The resistivity/temperature characteristics of PTC conductive polymers which have little or no cross-linking can be modified by stretching. The rate at which resistivity rises with temperature is increased, and the peak resistivity is decreased; however, the decrease in peak resistivity is substantially smaller than that observed with PTC conductive polymers having a high degree of cross-linking. Therefore, heat-recoverable electrical devices, particularly for covering telephone and other cable splices, comprise (a) a layer of a PTC conductive polymer which has little or no cross-linking, (2) an adjacent heat-recoverable layer of a PTC or ZTC conductive polymer which has a relatively high level of cross-linking, and (3) electrodes which can be connected to a power supply so that current passes through the layers and causes recovery of the device; preferably an uncrosslinked PTC layer is sandwiched between two cross-linked ZTC layers. Non-recoverable devices, e.g. heaters, can have valuable characteristics when they comprise PTC conductive polymer elements which have been given a relatively low degree of orientation by stretching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.