Self temperature limiting heat tracing strip of PTC (positive temperature coefficient) high polymer conductive composite material and preparation method thereof

Abstract

The invention discloses a self temperature limiting heat tracing strip of a PTC (positive temperature coefficient) high polymer conductive composite material, which comprises a flat strip that comprises a polyethylene PTC conductive complex layer. Two conductive core wires are extrusion coated inside the polyethylene PTC conductive complex layer. A polyethylene insulating layer, a shielding layer and a polyethylene reinforced protective layer closed in periphery are arranged orderly outside the polyethylene PTC conductive complex layer from inside to outside. The invention further discloses a preparation method of the self temperature limiting heat tracing strip, which comprises the steps of preparing the polyethylene PTC conductive complex layer; extrusion coating the two conductive core wires; and arranging the polyethylene insulating layer, the shielding layer and the polyethylene reinforced protective layer closed in periphery orderly outside the polyethylene PTC conductive layer from inside to outside. The self temperature limiting heat tracing strip provided by the invention will not generate bubbles, and is stable in electrothermal performance, safe and reliable. The preparation method provided by the invention has simple process flows and low cost, and is easy to realize.

Description

technical field [0001] The invention belongs to the technical field of PTC polymer electric heating materials, and in particular relates to a self-limiting temperature heating cable of PTC polymer conductive composite material and a preparation method thereof. Background technique [0002] Polymer composite materials with positive temperature coefficient (Positive temperature coefficient, PTC) effect can be used to make self-controlling intelligent heating cables. The PTC function can prevent local abnormal overheating, automatically control the change of current with temperature, and effectively control power consumption , Widely used in antifreeze, heat preservation, heating and other fields. [0003] The utility model patent with the publication number CN2916611 and the publication date of June 27, 2007 discloses an "electric heat tracing composite pipe", which consists of one or more pipes and an axially arranged pipe adjacent to the pipe. Or more than one PTC electric ...

AI Technical Summary

Problems solved by technology

[0005] The above existing technical solutions all have the following defects: 1) The thermal expansion coefficients of the conductive core wire and the PTC polymer heating element are different, and after repeated heating-cooling, the conductive core wire and the PTC polymer heating element are prone to form air bubbles, forming a hidden danger of electric ignition; 2 ) The leakage current of the self-limiting heating cable is large, which poses a safety hazard; 3) Since the conductive particles are prone to migration under the drive of the electric field and the electric heating temperature, the long-term use stability of the self-limiting heating cable is poor

Among them, the invention patent application with the publication number CN102103907A and the publication date of June 22, 2011 discloses "a manufacturing device and method for a two-core three-layer self-limiting temperature heating cable". The extruder head coats the two conductor cores with three layers of different compounds, which solves the fire hazard of the existing self-limiting temperature heating cable caused by electric ignition caused by the interface resistance of the metal conductor-resin heating element, and the insulation layer is irradiated. Shrinkage exposes the PTC heating layer and causes two quality problems of leakage and fire hazards

However, the method is complex and there is also the problem of large contact resistance between the conductive core wire and the PTC polymer material.

Irradiation cross-linking is a common method to improve the stability of self-limiting heating cables, but the manufacturing cost of heating cables increases, and the long-term use stability under high-voltage electric fields cannot be significantly improved

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