Prodn. of magnetic recording material - by casting dispersion of magnetic pigment and binder onto substrate in presence of calculated amt. of dispersion stabiliser

摘要

Prepn. of magnetic recording material consisting of a nonmagnetic support and at least one coating of a dispersion of a fine magnetic pigment in a polymeric binder. The binder is soluble in organic solvents and a dispersing agent is used. The amount of dispersing agent is calculated so that the ESA measurement (electroacoustic sound amplitude) has an absolute value of at least 10 mPa. sxmx volt-1, measured at 1 MHz in a dispersion of 2 wt. % magnetic pigment in 100 wt. % solvent. The ESA value is not increased by the addition of further dispersing agent. ADVANTAGE - Reproducible improvement in dispersion stability, lower flow limit and improved mechanical and magnetic properties of the prod.