Low-density polyethylene (LDPE) resin for cable insulant having voltage level of above 110kV, and preparation method thereof

Abstract

The invention discloses a low-density polyethylene (LDPE) resin for a cable insulant having a voltage level of above 110kV, and a preparation method thereof, and belongs to the field of LDPE resins. The LDPE resin is the characterized in that a melt flow rate is in a range of 0.1 to 10g/10min; density is in a range of 0.910 to 0.940kg/cm<3>; a degree of crystallization is in a range of 30 to 60%; molecular weight distribution Mw/Mn determined by a gel permeation chromatography is in a range of 2 to 7; fracture elongation is above 500%; a dielectric constant is below 4; a dielectric loss factor is below 6*10<-4>; volume resistivity is above 1.0*10<15>Omega.cm; and a maximum impurity size representing cleanliness is below 0.5mm. The preparation method of the LDPE resin comprises the following steps that 1, raw materials and a conditioning agent are subjected to compression boosting; 2, an initiator-peroxide solution is injected into the mixture obtained by the step 1 and undergoes a polymerization reaction; and 3, the polymerization system obtained by the step 2 is controlled and adjusted. The LDPE resin has specific performances, stable processing performances and physicochemical performances, and high cleanliness, and thus satisfying ultrahigh voltage cable insulation layer production requirements. The preparation method has relatively simple processes and adopts LDPE production equipment. Reaction conditions needed by the preparation method are easy to be satisfied.

Description

technical field [0001] The invention relates to an LDPE resin for cables and a preparation method thereof, in particular to an LDPE resin for 110kV and above voltage-resistant cable insulating materials and a preparation method thereof. Background technique [0002] LDPE resin is the abbreviation of Low Density Polyethylene. Its main properties are: tasteless, odorless, non-toxic, matte surface, milky white waxy particles, insoluble in water, slightly soluble in hydrocarbons, toluene, etc. It is resistant to most acids and alkalis, has low water absorption, can still maintain flexibility at low temperatures, and has high electrical insulation. Power cables are an important part of the wire and cable industry. In the field of power cables: 1-10kV belongs to low-voltage cables, 10-35kV belongs to medium-voltage cables, 110-220kV belongs to high-voltage cables, and 500kV belongs to ultra-high-voltage cables. [0003] Since the 1970s, high-voltage XLPE power cables have been pr...

AI Technical Summary

Problems solved by technology

[0009] One is the improvement of the impurity level, which is to improve the cleanliness of the material, that is, the so-called "ultra-purification", which requires that the LDPE resin does not produce large crystal points and oxidized particles during the synthesis process, and at the same time adopts appropriate transportation, storage and transportation methods to ensure Minimize the introduction of impurities, but the maximum size of impurities in the existing LDPE resin is more than 0.5mm, which cannot meet the production requirements of 110kV and above cable insulation materials;

[0010] The second is that conventional production methods need to be improved. The existing disclosed preparation methods require complex equipment, many operating steps, strict process conditions, and high costs

[0011] However, as far as the above difficulties are concerned, companies at home and abroad are conducting sufficient research and development, but unfortunately until the application of the present invention, although some companies can produce high-voltage cable insulation materials, they have not disclosed that they can be used for high-voltage cable insulation. We cannot clearly know the specific properties of LDPE resins, let alone how to produce LDPE resins with such properties; even if vinyl resins are disclosed, they are usually limited by special performance parameters, which cannot satisfy Requirements for high voltage cable insulation materials