| The industry of cable occupies an extremely status in national economy.At present,the domestic production capacity of PE cable-materials is approximately 200 thousand tons per year,while the quantity demanded is approximately 250 thousand tons per year.As a result,a large number of cable-resin is imported every year,especially the cross-linking PE rezin with a high voltage resistance.The rapid development of domestic cable and cable has led to a wide market development prospect in China,especially the high demand for high pressure and environmental protection cables.Low-density PE has an excellent electrical property and processing performance.By chemical cross-linking,its product can obtain an even higher degree of voltage resistance and usage temperature,which the dielectric strength could reach 50kV/mm and the operating temperature is 90 ℃.Now domestically the cross-linking PE rezin with a voltage resistance above 35 kV mainly rely on import,such as UCC HFDA-4201 SC and LE/LM4201 R 、 LE/LM4201 S from Borealis company and UBEC 180 from UBE Company.Meanwhile,there are few productions in domestic such as DJ210 from Shanghai petrochemical Company,2220 H from Yangzi-BASF Company and LD100 BW from Yanshan petrochemical company,which are far from the satisfaction of the domestic needs.The development of such product is desiderated.Aiming at this market,ethylene plant of Lanzhou petrochemical company has developed a LDPE cable-insulating product before.Basically it can meet the requirement of criterion as 35 kv cable-insulating material.However,compared to imported product,it still bare the problem of high dielectric constant and high attrition rate,long cross-linking time and large consumption,which reflects the distance on the property of breakdown resistance and cross-linking performance.It results in making the product less competitive.Aiming at these disadvantages,the propylene is used to replace propionaldehyde as molecular weight modifier creatively in order to control the structure of molecular chain of LDPE resin,as well as to improve the property of breakdown resistance;based on the free radical polymerization theory and combining the LDPE production technique,the method for controlling molecular weight distribution and degree of branching by polymerization technological parameter is figured out.By improving polymerization technological parameter,the content of double bond is increased.As a result,the cross-linking performance of Lanzhou product is improved to satisfy the custom needs,which leads to enhanced its competitiveness.The experiment of after processing with 2240 H is performed.The result indicates that the improved product of 2240 H has already met the requirements of criterion as 35 kv cable-insulating material. |
