▎ 摘　　要

NOVELTY - Double insulation type self-limiting temperature heating cable comprises metal wire cores, and the outside of two parallel metal wire cores is covered with a PTC material layer. The outer side of the PTC material layer is sequentially covered with an inner insulating layer and a flame-retardant outer insulating layer. The PTC material layer is made of polymer-based PTC material. The polymer-based PTC material includes the following raw materials: 70-80 pts. wt. polyethylene material, 7-8 pts. wt. modified graphene, 0.03 pts. wt. stabilizer, 30 pts. wt. carbon black and 10-12 pts. wt. compatibilizer. The modified graphene is prepared through the following steps (1) mixing graphene and water, stirring and dispersing under ice-water bath conditions, and (2) adding the pre-modified material and the branched modifier into chloroform, and vacuum-drying at 80°C until constant weight to obtain modified graphene. USE - The cable is used in electric heating element e.g. strip-shaped electric heater using resistivity positive temperature coefficient (PTC) conductive high polymer composite material as heating element. ADVANTAGE - The cable has good insulating performance, and improves the safety of the product. DETAILED DESCRIPTION - Double insulation type self-limiting temperature heating cable comprises metal wire cores, and the outside of two parallel metal wire cores is covered with a PTC material layer. The outer side of the PTC material layer is sequentially covered with an inner insulating layer and a flame-retardant outer insulating layer. The PTC material layer is made of polymer-based PTC material. The polymer-based PTC material includes the following raw materials: 70-80 pts. wt. polyethylene material, 7-8 pts. wt. modified graphene, 0.03 pts. wt. stabilizer, 30 pts. wt. carbon black and 10-12 pts. wt. compatibilizer. The modified graphene is prepared through the following steps (1) mixing graphene and water, stirring and dispersing under ice-water bath conditions, then adding ferric chloride solution and pyrrole, continuing stirring for 10-12 hours, after stirring, washing using water, centrifuging, detecting with silver nitrate solution, until there is no white precipitate, and vacuum-drying at 80°C to constant weight to obtain the pre-modified material, and (2) adding the pre-modified material and the branched modifier into chloroform, ultrasonically dispersing for 48 hours, and after the ultrasonic is finished, centrifuging at 4000 revolutions/minute for 30 minutes, and vacuum-drying at 80°C until constant weight to obtain modified graphene.