Graphene-doped polypropylene-based thermoplastic cable shielding material and preparation method thereof

Abstract

The invention relates to a graphene-doped polypropylene-based thermoplastic cable shielding material and a preparation method thereof, and the preparation method comprises the following steps: adding a polyethylene octylene co-elastomer into a first solvent to obtain a POE solution; adding graphene into a second solvent to obtain graphene slurry after ultrasonic dispersion; adding the graphene slurry into the POE solution, and carrying out suction filtration to obtain a flocculent mixture, so as to obtain a POE / graphene master batch; adding the polypropylene, the conductive carbon black, the POE / graphene master batch, the antioxidant and the coupling agent into an extruder, carrying out melt blending, carrying out water-cooling pelletizing, drying and dehydrating. According to the invention, graphene is added to form a synergistic effect with carbon black and improve the conductivity, and the graphene master batch is prepared by ultrasonic dispersion and a solution method, so that the problems of serious stacking and agglomeration of graphene layers are solved, better electrical properties and mechanical properties are obtained, and the conductivity of the graphene master batch is improved under the condition of meeting the conductivity. And a relatively low resistivity positive temperature effect is achieved.

Description

technical field [0001] The invention belongs to the field of cable semi-conductive shielding materials, in particular to a graphene-doped thermoplastic cable semi-conductive shielding material and a preparation method. Background technique [0002] Cross-linked polyethylene (XLPE) cables are currently the main medium and high voltage cables used in the power industry. Cross-linking enables polyethylene to obtain excellent thermal stability and mechanical properties, effectively improving the use of voltage levels and current carrying capacity, but after cross-linking The product changes from thermoplastic to thermosetting, which cannot be recycled after the cable life is exhausted, and it is difficult to dispose of, so it can only be buried or incinerated, causing serious environmental pollution and waste of resources, which does not meet the green development strategy proposed by the country; The cross-linking process in the three-layer co-extrusion production will produce ...

AI Technical Summary

Problems solved by technology

[0002] Cross-linked polyethylene (XLPE) cables are currently the main medium and high voltage cables used in the power industry. Cross-linking enables polyethylene to obtain excellent thermal stability and mechanical properties, effectively improving the use of voltage levels and current carrying capacity, but after cross-linking The product changes from thermoplastic to thermosetting, which cannot be recycled after the cable life is exhausted, and it is difficult to dispose of, so it can only be buried or incinerated, causing serious environmental pollution and waste of resources, which does not meet the green development strategy proposed by the country; The cross-linking process in the three-layer co-extrusion production will produce harmful cross-linking by-products such as methane and cumyl alcohol, which will form defects when the by-products accumulate in the cable, causing electric field distortion during operation, causing breakdown of the cable and eventually making the insulation failure , the control of by-products requires strict and precise temperature control, which increases the difficulty and cost of cable production

The development of thermoplastic cables has attracted more and more attention. At present, the main direction of thermoplastic cable research is polypropylene materials. Many scholars have carried out the development of polypropylene cable insulation materials, but there are few studies on the production of thermoplastic shielding materials. , the cable shielding material requires a room temperature volume resistivity of less than 100Ω·cm, and also needs to have a low positive temperature coefficient (PTC) effect. In order to meet this standard, it is usually necessary to add 30 to 40 wt% of carbon black. Such a filling amount is in It can be realized in high processing flow materials such as EVA and EEA commonly used in cross-linking systems, but in polypropylene materials used in non-cross-linking systems, high carbon black filling makes it difficult to disperse carbon black, and the smoothness and mechanical properties of the system decrease. It does not meet the requirements of cable operation, but also increases the viscosity of the system and increases the difficulty of processing and extrusion. Blending materials with high processing fluidity can solve this problem, but the thermal stability of the system will be affected. The balance of mechanical, thermal and processing properties is the focus of research on non-crosslinked cable shielding materials

Graphene is a two-dimensional carbon material with high electrical conductivity (700S / m). When it is added to the carbon black filling system as a second filler, the flake graphene will act as a point-to-point bridge, connecting nearby Carbon black particles can effectively improve the electrical conductivity and reduce the filling amount of carbon black in the system, but graphene materials are difficult to disperse during melt blending, and the stacking of sheets reduces the synergy, which will further reduce the mechanical properties

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