Magnetic recording medium with increased dispersion stability

摘要

Magnetic recording medium comprises, on a non-magnetic substrate, a magnetic dispersion(s) comprising (i) a pigment dispersed in a polymeric binder; and (ii) a codispersant comprising quat. ammonium cpd., guanidine, piperidine, alkylated or ethoxylated amine, ethanolic KOH soln., metal alkoxylate, Grignard cpd. or metal hydride. The dispersant pref. comprises a diamine having tert. substn., a polyamine (mixt.), sodium borohydride, sodium boronate, the Li or K cpd. thereof, lithium aluminium hydride or lithium alanate, LiH or NaH or KH in oil, LiH suspension, sodium amide suspension in toluene, LiNH2, potassium tri-sec-butylborohydride or K selectride. The codispersant comprises tetra-n-alkylammonium hydroxide, pentaalkylguanidine, pentaisoalkylguanidine, piperidine or ethanolic KOH soln., and is added in amt. of 0.15-4 wt.%, based on the pigment.