| 摘要 |
PURPOSE:To ease manufacturing, installation, maintenance, and inspection work by forming a sign body suck as a signpost of a heat generating body, which is made of a specific composite having a positive temperature coefficient characteristic in a low temperature region, so that the heating body generates the heat automatically in order to melt snow and ice when the temperature goes down. CONSTITUTION:In a signal body such as a traffic sign board 1, a heating body 4, which is covered with an insulating film 3, is attached to the back and inner surface of a sign casing 2, which is made of steel or the like and whose front surface is used as a sign face, and the back and opening part of the casing 2 is formed by sealing it with a back plate 5 consisting of an insulating and protective material. A pair of electrodes 6 are installed on the surface of the heat generating body 4, and each electrode 6 is connected to the power source via each lead wire 7. At this time, the heating body 4 consisting of a kneaded composite of crystalline polymer and carbon black is formed with a composite having a positive electric characteristic such that the ratio of its maximum electric resistance to the room-temperature-electric-resistance is more than 10<3> and moreover the temperature, at which its electric resistance is 10 times the room-temperature-electric-resistance, lies between 40 to 80 deg.C. |
