公开(公告)号：DE2428875A1

公开(公告)日：1976-01-02

申请号：DE2428875

申请日：1974-06-14

Applicant: BASF AG

Inventor： GRAU WERNER DR ,  KOPKE HELMUT ,  OHLINGER MANFRED DR ,  SCHNEEHAGE HENNING DR ,  SCHOENAFINGER EDUARD DR

IPC: C01G49/06 ,  G11B5/706 ,  H01F1/11 ,  G11B5/68

Abstract: A process for the manufacture of acicular gamma-iron(III) oxide which, because of its improved dispersibility in organic binders, is suitable for the manufacture of magnetic recording media exhibiting a particularly high orientation ratio. For this purpose, the non-magnetic acicular alpha -iron(III) oxide or goethite pigment is treated with from 0.5 to 10% by weight, based on the pigment, of a compound of the formula I: (I) where R1, R2 and R3 are hydrogen, alkyl of 1 to 24 carbon atoms or alkenyl of 1 to 24 carbon atoms and (RX)- is selected from the group consisting of an aliphatic carboxylic acid of 1 to 18 carbon atoms, an aromatic carboxylic acid of 1 to 18 carbon atoms, a sulfonic acid and an ester of phosphoric acid and is then further processed by conventional methods to give gamma-iron(III) oxide.

公开(公告)号：DE2434096A1

公开(公告)日：1976-02-05

申请号：DE2434096

申请日：1974-07-16

Applicant: BASF AG

Inventor： SCHNEEHAGE HENNING DR ,  WUNSCH GERD DR ,  KOESTER EBERHARD DR ,  SCHOENAFINGER EDUARD DR

IPC: B22F9/22 ,  C09C1/62 ,  H01F1/06 ,  G11B5/62

Abstract: A process for the manufacture of acicular ferromagnetic metal pigments containing iron, having a reduced field strength distribution and a steeper residual magnetization curve, by applying equivalent amounts of an alkaline earth metal cation and of a monobasic, dibasic or tribasic aliphatic carboxylic acid of up to 6 carbon atoms onto appropriate acicular iron oxides and then reducing the treated oxides.