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Patent Agency Ranking
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
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.
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公开(公告)号：DE2538792A1
公开(公告)日：1977-03-17
申请号：DE2538792
申请日：1975-09-01
Applicant: BASF AG
Inventor： SCHOENAFINGER EDUARD DR , DEIGNER PAUL DR , KOESTER EBERHARD DR , OHLINGER MANFRED DR , SCHAEFER DIETER DR , STUMPFI WERNER DR , AMORT JUERGEN DR , SEILER CLAUS-DIETRICH DR , NESTLER HEINZ DR , AMBROS OTTO DR
Abstract: Stabilisation of magnetic dioxide pigments for prepn. of magnetic registering matls. is effected by (a) suspending the pigment in an aqs. and/or alcoholic medium (b) treating the suspended pigment with a silane of formula RnSi(OR')4-n (where R is a 1-18C org. gp; R' is a 1-8C aliphatic org. gp.; and n is 1-3), or with a hydrolysis prod. of this silane, so that least partly hydrolysed silane is situated on the surface of the pigment, after the latter has been separated from the medium, and (c) drying the separated pigment at 50-200 degrees C. Retain their good magnetic properties, even under unfavourable climatic, e.g. hot and humid conditions. The pigments are also easily dispersed and worked.
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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
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.
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公开(公告)号：DE2459766A1
公开(公告)日：1976-07-01
申请号：DE2459766
申请日：1974-12-18
Applicant: BASF AG
Inventor： SCHOENAFINGER EDUARD DR , DEIGNER PAUL DR , KOESTER EBERHARD DR , OHLINGER MANFRED DR , SCHAEFER DIETER DR , STUMPFI WERNER DR
Abstract: Chromium dioxide magnetic pigments are stabilised against loss of magnetic properties by (a) treating an alcoholic or aq. alcoholic suspension of the pigment with a hydrolysis prod. of a silane RnSi(CR')4-n where R = 3-18 C aliphatic org. gp., R' = 1-8C aliphatic org. gp. and n=1-3, such that it remains at least partially on the surface of the pigment after separating the pigment from the medium, and (b) drying the treated pigment at ca 50-200 degrees C. gives pigments useful in making magnetic tapes etc. which are resistant to loss of magnetic properties under advers (hot and moist) climatic conditions; gives better protection than known processes in which e.g. a thin chromium oxide layer or an inorg. metal phosphate layer is deposited on the pigment surface. The pigments also have improved dispersibility and processability.
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