Patent ID: 6777468
Filing Date: 2004-08-17
Classification: C09K,D21H

Abstract:
A composition for a soft sealing material characterized in that it has the following percentage composition based on the overall composition:from 4 to 9 wt. % of fibrillated polyaramide fibers, less than 60 wt. % of powder graphite having a carbon content of 90 to 92 wt. % and such particle size distribution that at least 85% of all particles are in the size range of 10 &mgr;m to 50 &mgr;m, about 30 wt. % of mineral fillers represented by a combination of microsilica having a SiO2 content between 90 and 95 wt. %, a specific surface area according to BET method of 15 to 25 m2/g and such particle size distribution that at least 90 wt. % of all particles are in the particle size range under 5 &mgr;m, and of an active mineral filler having a SiO2 content of at least 98 wt. %, a specific surface area according to BET method of 100 to 120 m2/g and such particle size distribution that at least 90 wt. % of all particles are in the particle size range of 5 &mgr;m to 50 &mgr;m, the ratio of microsilica to the mineral filler being such that the value of the total specific surface area according to BET method is between 45 and 55 m2/g; and, optionally, friction agents for enhancing the friction between graphite particles and, optionally, biosoluble mineral fillers, about 12 wt. % of elastomeric binders, up to 2 wt. % of a vulcanization system in paste from containing zinc dibenzyldithiocarbamate (ZBEC) or zinc 2-ethylhexyldithiophosphate (ZDT) as vulcanization accelerants, and optionally usual auxiliary substances.