Two-step method silane natural crosslinking overhead polyethylene insulation material and preparation method thereof

Abstract

The invention discloses a two-step method silane natural crosslinking overhead polyethylene insulation material and a preparation method thereof, wherein the two-step method silane natural crosslinking overhead polyethylene insulation material is prepared from the following raw materials in parts by weight: 85 to 95 parts of linear low density polyethylene, 50 to 60 parts of high density polyethylene, 2 to 6 parts of polypropylene, 10 to 15 parts of aluminum hydroxide, 1 to 3 parts of silane crosslinking agents, 0.5 to 2 parts of organic auxiliary agents, 1 to 2 parts of rheological agents, 1to 3 parts of complex antioxidants, 0.3 to 1 part of catalysts, 1 to 3 parts of copper ion inhibitors and 0.2 to 0.5 part of processing auxiliary agents. The produced insulation material achieves thegoals of effectively reducing the silane crosslinking time, reducing the energy consumption for cable plants, reducing the cost and effectively improving the production efficiency.

Description

technical field [0001] The invention belongs to the field of cable materials, and in particular relates to a two-step silane natural cross-linked overhead polyethylene insulating material and a preparation method thereof. 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 p...

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 cross-linked polyethylene 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 cross-linked polyethylene, the shrinkage rate of cross-linked polyethylene is very low. Large, especially when producing small-sized cables, the shrinkage rate of XLPE is even more obvious, which leads to the exposure of the conductors at the connection part and the end part of the silane XLPE cable, resulting in the so-called insulation shrinkage phenomenon. That is to say, the heat yield 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 big