PURPOSE: To maintain the constant quality of an organic flat exothermic body, and enable a mass production system to be applied to the manufacture thereof by impregnating a base material with a composite having a positive temperature coefficient and containing crystalline polymer and conductive substance for the manufacture of a heating element, and then bridging the composite to the base material.
CONSTITUTION: Polyethylene, polypropylene or the like is used as crystalline polymer, while carbon black containing graft bonded organic polymer, or the like is used as a conductive substance. Also, pigment, MgO, barium titanate or the like of high heat conductivity is blended to improve positive temperature coefficient characteristic. A blending ratio of the crystalline polymer to the conductive substance is taken at 100 pts.wt. to a value between 30 and 120 pts.wt., or preferably a value between 50 pts.wt. and 90 pts.wt. A base material is impregnated with a composite of such a material in liquid state, and dried. Then, the base material is again treated, dried and bridged, using the material composite. Namely, the material composite is first impregnated with the base material and then again coated with a similar composite after drying, thereby providing a stable resistance value at conventional resistance value level.
HAYASHI YUICHI
FURUKAWA KIYOSHI
