Low-retraction one-step process silane crosslinked polyethylene insulation material

Abstract

The invention relates to a low-retraction one-step process silane crosslinked polyethylene insulation material, comprising linear low density polyethylene (LLDPE), high-density polyethylene (HDPE), polypropylene, a silane crosslinking agent, an initiator, an antioxidant, a copper ion inhibitor, a catalyst, a processing agent and an anti-shrinking agent. Compared with a two-step process low-retraction silane crosslinked polyethylene insulation material in the market, the low-retraction one-step process silane crosslinked polyethylene insulation material is simple in production process, fast in operation and production speed, high in surface glossiness, low in cost, wide in production temperature applicability, good in electric property and good in thermal endurance.

Description

technical field [0001] The invention relates to a low-retraction one-step silane cross-linked polyethylene insulating material. Background technique [0002] Cross-linked polyethylene has the characteristics of high volume resistivity, low dielectric loss, good heat aging resistance, good stress crack resistance, easy processing, and low price. It is an excellent insulating material. At present, cross-linked polyethylene mainly has three methods: peroxide cross-linking, radiation cross-linking and silane cross-linking. Among them, silane crosslinked polyethylene is prepared by grafting or copolymerizing crosslinkable alkoxysilane into the main chain of polyethylene. Silane cross-linked polyethylene cables can be cured and cross-linked after being placed in warm water for several hours after extrusion. Since silane crosslinking does not require special crosslinking equipment, the process control is relatively simple, and the electrical performance is excellent, it has incom...

AI Technical Summary

Problems solved by technology

However, when the extrusion die is used to produce silane cross-linked polyethylene insulated cables, the stretching is relatively large, and the faster stretching speeds up the crystallization between polyethylene molecules, and after silane grafting, the number of branched chains on the polyethylene molecular chain increases , the pre-crosslinking between molecules increases, the melt flow rate of silane crosslinked polyethylene cable material decreases, and the mutual movement between molecules is difficult, resulting in the polyethylene macromolecular chain changing from a curled state to an extended state when stretched

At the same time, after the silane XLPE cable is cabled, it is cross-linked in water or in a natural state, which is below the melting point of polyethylene. Under the elastic recovery force of XLPE, the shrinkage rate of XLPE is very low. Large, especially when producing small-sized cables, the shrinkage rate of XLPE is even more obvious, causing the conductors of the connection part and the end part of the silane XLPE cable to be exposed, resulting in the so-called insulation shrinkage phenomenon, That is to say, the heat recovery rate of XLPE insulated cables is not easy to pass

In order to achieve a lower thermal shrinkage index, when producing insulated cables with silane XLPE cable insulation materials, it is often necessary to strictly control the stretch ratio and adopt high cooling water temperature and other measures, resulting in low production efficiency, high scrap rate, and consumption. Can be large, sometimes especially when producing small cross-section wires, the thermal shrinkage rate often does not meet the requirements

The silane cross-linked polyethylene insulated wire and cable produced in this case caused the cable to fail or be replaced due to the retraction of the insulation layer

Patent CN 1699457 A: Silane crosslinked low shrinkage polyethylene plastic and its preparation method and application and patent CN 102286186 A: Silane crosslinked polyethylene, wires and cables The heat recovery shrinkage of silane crosslinked polyethylene cable material is described and Improvements have been made, but both are two-step silane cross-linked polyethylene cable materials, the production process is complicated, the cost is high, and the use is limited

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