Preparation of high quality impregnating pitch by new route

Abstract

High quality impregnating pitch with low quinoline insoluble (QI) content and high coking value (CV) is required during the production of ultrahigh power graphite electrodes and C/C composites. High quality impregnating pitch using medium temperature coal tar pitch as raw material was prepared by a new route. The medium temperature pitch was first thermally treated to increase the CV and the β-resin content, then the QI was separated and removed by sedimentation with mixed solvent. For the traditional process technology, thermal polymerisation is operated after the removal of QI. The effects of sedimentation temperature, solvent ratio, aromatic/aliphatic ratio and sedimentation time on QI content, softening point (SP) and CV of impregnating pitch were discussed. The optimal process conditions were determined. The samples of high quality impregnating pitch with 82°C of SP, <0·14% of QI content and >52·22% of CV were obtained by adjusting the operating conditions. The CV of 52·22% was significantly higher than that of the impregnating pitch by the traditional process technology using medium temperature coal tar pitch as raw material.