| 摘要 |
PROBLEM TO BE SOLVED: To provide a durable heating element maintaining high performance in a specific temperature range, by making up a heating resistance element out of a conductive constituent of spherical, flaky, or whisker-shaped graphite and an insulating constituent of polyimide, and adapting the graphite to have a specific degree of graphitization calculated by the Mering-Maier formula. SOLUTION: An insulating layer 3 coated with a varnish-like polyimide resin is provided on a metallic substrate 2, a heating resistance element 4 is formed by baking and fixing conductive paste made by mixing a conductive constituent of graphite with an insulating constituent of the varnish-like polyimide resin onto the insulating layer 3, and an electrode metal part 6 is attached to each electrode part 5. When the degree of graphitization calculated by the Mering-Maier formula is 35% or more, high performance is maintained in a range from room temperature to 250 deg.C. Preferably, the graphite comprises a constituent having a degree of graphitization of 35 to 94% calculated from the Mering-Maier formula and a constituent having that of 95% or more, and the volume ratio of the two is 0:100 to 80:20. |
