公开(公告)号：JPH03171425A

公开(公告)日：1991-07-24

申请号：JP22851690

申请日：1990-08-31

Applicant: BASF AG

Inventor： FURIIDORIHI ZOMAAMAN ,  NORUBERUTO SHIYUNAIDAA ,  GERUTO EERUHARUTO ,  RUUTOBUIHI KURAITONAA ,  BUERUNAA GURAU ,  AUGUSUTO REENAA ,  HANSU RAIHIERUTO

IPC: G11B5/842

Abstract: PURPOSE: To make it possible to obtain a dispersion which is excellent in a dispersion treatment by preparing this dispersion by stirring spherical frictional grinding media having a sp. gr. smaller than the sp. gr. of a magnetic material at a specific number of revolutions in a cylindrical hermetic frictional grinding vessel of a specific size. CONSTITUTION: This dispersion is prepd. by stirring the spherical frictional grinding media, which have the ratio of a length to diameter of 1.3 to 2.5:1, have the sp. gr. smaller than the sp. gr. of the magnetic material and have a diameter from 0.5 to 3mm in the cylindrical hermetic frictional grinding vessel loaded with these media by an anchor mixer or spiral mixer at 50 to 1000R.P.M. As a result, the magnetic material is treated extremely gently treated without damaging the acicular crystals in the shortest possible dispersion treatment time, by which the homogeneous and stable dispersion is obtd.