| With the rapid development of the national economy,the domestic demand for electricity is becoming more and more urgent.The research of insulating material in high voltage transmission project has been a hot spot at home and abroad.In this paper,The research of high performance halogen-free-flame-retardant laminates for UHV power transmission and transformation was carried out with the background of demand for HV-Transmission insulation materials.The modified epoxy resin was used as the resin matrix and the glass cloth was used as the reinforcing material.The halogen-free-flame-retardant epoxy resin glass cloth laminate was prepared by hot pressing technology.The resin synthesis process and the preparation process of halogen-free-flame-retardant epoxy resin glass cloth laminated board were systematically studied.On this basis,the key insulation product of the UHV power transmission-insulated slotted wedge was also researched.In this paper,phosphorus-containing epoxy resin was prepared by grafting reaction.The proper storage time of this kind of resin system was 8-10 days.It was found that when the phosphorus content≥3%,the vertical combustion level of resin system can reach to the UL 94 V-0 level and it possesses a good flame retardant properties.The curing kinetics of phosphorus-containing epoxy resin shows that,the theoretical gel-temperature was 137.615℃,the theoretical curing temperature was 182.295℃and the theoretical post-treatment temperature was 243.73℃.The results show that the flame retardancy of the resin system can reach to the UL94 V-0 level,when the amount of aluminum hydroxide is 50%(mass fraction)under the condition that the resin system contains no phosphorus.But the addition of aluminum hydroxide will affect the mechanical properties of the resin system.When its content is over 30%,the decline of the mechanical properties will show an increasing tendency.On the basis of the modified epoxy resin,the epoxy resin was used as the matrix,the glass cloth was used as the reinforcing material and the halogen-free-flame-retardant epoxy glass cloth laminated boards were prepared by using of the hot pressing technology.The addition of glass cloth can improve the flame retardancy level of the whole composite materials.When the phosphorus content≥1.5%,the flame retardant properties of the laminates can reach UL 94 V-0 level;When the phosphorus content is2%,the comparative tracking index(CTI)of the epoxy glass cloth laminates is 600V,its electrical properties are excellent;the water absorption of the laminate is 0.0197 and it possesses a good hydrophobic effect.The further research found that the increasing phosphorus content will cause the mechanical properties of laminates increased firstly and then decreased.When the phosphorus content was 2%,the tensile strength,flexural strength and impact strength reached the maximum value,the tensile strength reached 505 MPa,the flexural strength reached 587 MPa and the impact strength reached 88.3 kJ/m~2.The addition of aluminum hydroxide can reduce the mechanical properties of the laminates.It was confirmed by using of the scanning electron microscopy(SEM)of the cross-section of the samples.The high-mechanical-property glass cloth can enhance the mechanical properties of the laminates.When the potion of high-mechanical-property glass cloth in the pre-impregnated material is 40%,the laminate tensile strength can reach 549 MPaIn order to realize the localization of insulating construction for UHV converter valve,in this paper,the key insulation product-slot wedge was studied.Through the finite element analysis,it is found that the stress range of each stress point should be not less than 150mm×50mm in the actual application of the insulation slot wedge;Through the study of mold design,the problem of mold side wall stress and the whole temperature control is solved.Based on the study of pressing technology of laminated board,the pressing process of insulating slot beam is formed. |
