| 摘要 |
PURPOSE:To improve the heating efficiency and safety by a method wherein a sheet shaped heating body is formed of a mixed composition which contains a crystallizable polymer and carbon black and has specific positive temperature coefficient characteristics. CONSTITUTION:A heating body which is placed in a panel for heating is formed of a resin composition which has specific positive temperature coefficient characteristics. The composition is formed of a resin composition of which the maximum electrical resistance value has a ratio which is not less than 10<3> to the electrical resistance value at a room temperature, and which has positive temperature coefficient characteristics in which a temperature to show the 10 time electrical resistance value of the room temperature electrical resistance value stays in a range of 40-80 deg.C. For the composition with the positive temperature coefficient characteristics, a specific crystallizable polymer and carbon black are mixed by a specific ratio, and an appropriate kneading is done. For the crystallizable polymer, ones of which crystalline melting point stays in a range of 50-100 deg.C are used, and e.g. ethylene-acrylic ester copolymer or ethylene-vinyle acetate copolymer, etc., is suitable. Also, for the carbon black, acetylene black or oil furnace black is desirable, and especially ones of which particle diameter is from 20 to 100mum are used. |
