公开(公告)号：DE4213061A1

公开(公告)日：1993-10-28

申请号：DE4213061

申请日：1992-04-21

Applicant: BASF MAGNETICS GMBH

Inventor： VAETH GUENTER ,  FESER RAINER DR ,  LOESER WERNER DR ,  OHLINGER MANFRED DR

IPC: C01G49/06 ,  H01F1/11 ,  G11B5/858

公开(公告)号：DE4425873A1

公开(公告)日：1996-01-25

申请号：DE4425873

申请日：1994-07-21

Applicant: BASF MAGNETICS GMBH

Inventor： AUWETER HELMUT DR ,  LOESER WERNER DR ,  PFANNEBECKER EMIL ,  SCHNEIDER NORBERT ,  JAKUSCH HELMUT DR ,  WIETHOELTER DIETER DIPL ING

IPC: C09D5/23 ,  G11B5/70 ,  G11B5/706 ,  G11B5/84 ,  G11B5/68

Abstract: The process concerns the prodn. of a magnetic recording medium, which has a non-magnetic substrate and coating(s) of magnetic dispersion comprising a mixt. of finely-divided magnetisable pigments which differ in morphology and/or particle size, finely dispersed in a polymeric binder matrix and opt. other additives. The novelty is that the mixed and/or co-compacted pigments are added to the dispersion and the pigment mixt. contains (a) 60-95 wt.% acicular pigment(s) (I) with a BET value of 15-45 m /g and (b) 5-40 wt.% acicular pigment(s) (II) with a BET value at least 5 m /g higher than that of (I).

公开(公告)号：DE19638035A1

公开(公告)日：1997-04-03

申请号：DE19638035

申请日：1996-09-18

Applicant: BASF MAGNETICS GMBH

Inventor： AUWETER HELMUT DR ,  LOESER WERNER DR ,  PFANNEBECKER EMIL ,  SCHNEIDER NORBERT ,  JAKUSCH HELMUT DR ,  WIETHOELTER DIETER ,  KOERNER REINHARD DR ,  OHLINGER MANFRED DR

IPC: G11B5/842 ,  G11B5/84

Abstract: The magnetic recording material has a non magnetic carrier which is coated with a polymer binding material that contains a dispersion of fine pigments of needle type magnetic particles. Two types of pigment are used with the first having a concentration of 15-45 meters per gram and the second having 5 meters per gram higher. The mix is with a first pigment of 50-59 % and the second pigment with 41-50%.

公开(公告)号：DE4138700A1

公开(公告)日：1993-05-27

申请号：DE4138700

申请日：1991-11-26

Applicant: BASF MAGNETICS GMBH

Inventor： VAETH GUENTER ,  PFANNEBECKER EMIL ,  LOESER WERNER DR ,  OHLINGER MANFRED DR

IPC: C01G49/06 ,  G11B5/706

Abstract: Prodn. is claimed of needle-like gamma-Fe(III) oxide modified with Sn-dioxide from Fe(III) oxide hydroxide contg. Lepidocrokite obtd. by adding alkalis to an aq. Fe(II) salt soln. under simultaneous oxidn. by introducing air into the aq. suspension, reducing the Fe(III) oxide hydroxide with H2 at 280-550 deg.C to magnetite and subsequently oxidising the magnetite with O2-contg. gases at 200-380 deg.C to form needle-like gamma-Fe(III) oxide. The prodn. of the Fe(III) oxide hydroxide contg. 5-40 wt.% residual Fe(III) the Sn-dioxide in an amt. of 0.1-1.0 wt.% is pptd. to aq. suspension by adding a hydrolisable Sn-cpd. and then the residual Fe(II) converted to Fe(III) oxide hydroxide. The Sn-dioxide-contg. Fe(III) oxide hydroxide is pref. tempered before being reduced to magnetite at 280-550 deg.C. USE/ADVANTAGE - The ferromagnetic Fe(III) oxide can be used in the prodn. of magnetic recording supports. It has a high coercive field strength and consists of stable individual particles which are not destroyed in the dispersing process necessary for the mfr. of magnetic supports.