| 摘要 |
PROBLEM TO BE SOLVED: To obtain a PTC composition which has a sufficiently low resistance value in a steady state and a small increase in resistance, by providing a compound composition which has a polymer component and metal carbide powder as main components and has a positive temperature characteristic(PTC) of electrical resistance, and setting a component ratio of the metal carbide powder within a certain range of the entire compound composition. SOLUTION: A positive temperature characteristic(PTC) composition is formed by heating and mixing at 130 to 200 deg.C a crystalline high-density polyethylene which has a melting point of about 130 deg.C as a polymer component, and an ethylene copolymer with a melting point of about 70 deg.C so as to set a volume ratio at 0 to 80 vol.%. Next, the polymer component is heated and mixed with metal carbide powder such that a ratio of the power is varied from 45 to 55 vol.% relative to the polymer. Thus, a polymer composition is obtained. TiC, WC, and ZrC having a particle diameter of about 1 to 10 μm are used as the metal carbide powder. The obtained mixture is mixed with an organic peroxide cross-linking agent with 0.01 to 30 wt.% at 130 to 180 deg.C. After the composition is powdered, thermo-compression molding is carried out. |
