FLEXIBLE HEATING ELEMENTS AND PROCESSES FOR THE PRODUCTION THEREOF

摘要

Flexible heating elements, for example, suitable for use in electric blankets and processes for their production are described. The flexible heating element comprises at least two flexible electrical conductors spaced apart by a PTC material, an amorphous highly conductive rubber compatible with the PTC material and adhered to each conductor being interposed between the PTC material and each conductor whereby in use current passes from one conductor to another through the PTC material via the highly conductive rubber, the conductors being spaced sufficiently close to one another to ensure that when energised the PTC material heats substantially uniformly without exhibiting a significant temperature gradient between the conductors and that any abnormal temperature increase increases the temperature of all the PTC material between the conductors in the region of the abnormal temperature increase, the arrangement being such that in use the contact resistance between the conductors and the PTC material is reduced by the amorphous highly conductive rubber interposed therebetween. The flexible heating element is produced by extruding the amorphous highly conductive rubber to cover each flexible electrical conductor and subsequently or simultaneously extruding the PTC material to cover the amorphous highly conductive rubber.