A new type of lipophilic hydrophobic self-repairing cellulose insulating paper developed with ST-110/FAS/PTFE ternary system as coating substrate

The moisture generated by the ageing of the oil-paper insulating system can easily lead to the deterioration of the performance of the insulating paper. In order to alleviate the impact of moisture on the performance of the insulating paper, we developed a kind of lipophilic hydrophobic self-repairing cellulose insulating paper (new insulating paper) based on the ternary system of polytetrafluoroethylene, fluorocarbon surfactant and fluorinated alkyl silane, and accelerated thermal ageing test for 45 days at 130°C was carried out. The experimental results show that the new insulating paper with excellent lipophilic property can realise hydrophobic self-repairing through heat treatment after physical damage. The tensile strength and elongation at break of the new insulating paper increased by 5%–8% and 6.25%–27% respectively compared with the original cellulose insulating paper. At the end of ageing, the relative dielectric constant and dielectric loss factor of new insulating paper are 10.4% and 9.9% lower than that of the original cellulose insulating paper, while the breakdown voltage is 6.8% higher. The acid and moisture content produced during the ageing process of the insulating oil impregnated with new insulating paper are also less, indicating that the coating can delay the ageing of the insulating paper.