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公开(公告)号：DE2540874A1
公开(公告)日：1977-03-24
申请号：DE2540874
申请日：1975-09-13
Applicant: BASF AG
Inventor： OHLINGER MANFRED DIPL CHEM DR , GRAU WERNER DIPL CHEM DR , STRITZINGER HEINZ DIPL ING , SCHOENAFINGER EDUARD DIPL CHEM
Abstract: Prod. having high coercive force is produced by pptg. Co(OH)2 from a Co(II) salt soln. with ammonia onto goethite crystallised from an alkaline soln. The prod. is subjected to reduction into magnetite. Subsequently the magnetite is oxidised with O2 at 200-400 degrees C to produce cobalt doped gamma-Fe2O3. Process is improved by pretreating the surface of goethite (before the introduction of the Co(II) salt) with an acid having pK 4.8; adjusting pH to 3-7 and maintaining the surface acidity within this range to the end of the redn. process. gamma-Fe2O3 suitable for magnetic recording is produced. Its coercive force is increased (compared with the known material) by the increased quantity of the cobalt dopant. The above process permits an increase in the cobalt doping without impairing the thermal stability and the toughness of the product. The reduction stage can be carried out at temps. as low as 250-290 degrees C.
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公开(公告)号：DE2520643A1
公开(公告)日：1976-11-18
申请号：DE2520643
申请日：1975-05-09
Applicant: BASF AG
Inventor： KOESTER EBERHARD DIPL PHYS DR , WUNSCH GERD DIPL CHEM DR , SCHOENAFINGER EDUARD DIPL CHEM , SCHNEEHAGE HANS HENNING DIPL C
Abstract: A process for the manufacture of acicular gamma-iron(III) oxide, in which the non-magnetic, acicular iron(III) oxide is treated with a solution of a compound of the formula I (I) where R1 and R2 are or O-R5, R3 is H, OH, or O-R5, R4 is alkyl or cycloalkyl of 1 to 16 carbon atoms and the R4's may be identical or different, and R5 is alkyl, cycloalkyl or aralkyl of 3 to 18 carbon atoms, and is then converted to gamma-iron(III) oxide by reduction to magnetite, followed by oxidation.
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公开(公告)号：DE2550307A1
公开(公告)日：1977-05-18
申请号：DE2550307
申请日：1975-11-08
Applicant: BASF AG
Inventor： OHLINGER MANFRED DIPL CHEM DR , SCHOENAFINGER EDUARD DIPL CHEM , SCHNEIDER WALTER , STRITZINGER HEINZ DIPL ING , VAETH GUENTER
Abstract: Acicular gamma-iron(III) oxide is manufactured by reacting an iron(II) salt solution with an aqueous solution of an alkali metal hydroxide and oxidizing the resulting suspension of iron(II) hydroxide in three stages. In a first stage, at most from 0.1 to 4% by weight of the amount of iron(II) hydroxide originally present is oxidized in the course of from 0.1 to 4 hours, in a second stage from 10 to 25% by weight of the said original amount are oxidized in the course of from 1.5 to 6 hours and in a third stage the remaining amount is oxidized. After the oxidation, the goethite formed is reduced to magnetite and the latter is then oxidized to acicular gamma-iron(III) oxide.
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公开(公告)号：DE2461937A1
公开(公告)日：1976-07-08
申请号：DE2461937
申请日：1974-12-31
Applicant: BASF AG
Inventor： OHLINGER MANFRED DIPL CHEM DR , STRITZINGER HEINZ DIPL ING , HARTMANN JOB-WERNER DIPL CHEM , SCHOENAFINGER EDUARD DIPL CHEM
Abstract: In the prodn. of acicular alpha-Fe2O3 (I) by pptn. of hydrated alpha-Fe2O3 (II) from aq. Fe(II) salt solns. with alkali, with simultaneous oxidn. with air, and dehydration, polymers (III) contg. carboxyl gps. with an acid no. of over 50, pref. 80-220, are added during the prodn. of (I). (III) pref. is added to the (II) suspension in an amt. of 1.5-10, esp. 3-6 (wt.) pts/100 pts. (II). (III) can be (co)polymers of an alpha,beta-unsatd. carboxylic acid or reaction prods. of phthalic acid or anhydride with polyalcohols. (I) is used for the prodn. of acicular gamma-Fe2O3 (IV), which is used for low-noise magneto-gram carriers. The (I) obtd. gives esp. low-noise (IV) with good controllability and without additional process stages.
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公开(公告)号：DE2550308A1
公开(公告)日：1977-05-18
申请号：DE2550308
申请日：1975-11-08
Applicant: BASF AG
Inventor： OHLINGER MANFRED DIPL CHEM DR , SCHOENAFINGER EDUARD DIPL CHEM , VAETH GUENTER , STRITZINGER HEINZ DIPL ING , KOESTER EBERHARD DIPL PHYS DR , SCHNEEHAGE HANS HENNING DIPL C , STECK WERNER DIPL CHEM DR
Abstract: Goethite is obtained by reacting an aqueous solution of an iron (II) salt with an aqueous solution of an alkali metal hydroxide and oxidizing the resulting iron(II) hydroxide. The oxidation is carried out in three stages. In the first stage, from 4 to 15% by weight are oxidized in the course of from 0.4 to 5 hours, in the second stage from 60 to 85% by weight are oxidized in the course of from 1.5 to 6 hours and in a third stage the remaining amount of iron is oxidized.
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Patent Agency Ranking
公开(公告)号：DE2550225A1
公开(公告)日：1977-05-18
申请号：DE2550225
申请日：1975-11-08
Applicant: BASF AG
Inventor： VAETH GUENTER , OHLINGER MANFRED DIPL CHEM DR , STRITZINGER HEINZ DIPL ING , SCHOENAFINGER EDUARD DIPL CHEM , WETTSTEIN EUGEN , GUTH WOLFGANG
Abstract: Acicular gamma -iron(III) oxide is manufactured by reacting an iron(II) salt solution with aqueous solutions of alkali metal hydroxides and oxidizing the resulting suspension of iron(II) hyroxides in 3 stages. In the first stage not more than 8 percent by weight of the iron(II) hydroxide originally present is oxidized over a period of 0.5 to 4 hours, in the second stage from 25 to 55 percent by weight over a period of 1.5 to 6 hours and the remainder thereof in a third stage. Following this oxidation, the goethite formed is reduced to magnetite, which is then oxidized to acicular gamma -iron(III) oxide.
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公开(公告)号：DE2447386A1
公开(公告)日：1976-04-22
申请号：DE2447386
申请日：1974-10-04
Applicant: BASF AG
Inventor： KOESTER EBERHARD DIPL PHYS DR , WUNSCH GERD DIPL CHEM DR , SCHOENAFINGER EDUARD DIPL CHEM , SCHNEEHAGE HANS HENNING DIPL C , JAKUSCH HELMUT DIPL PHYS DR
Abstract: A process for the manufacture of acicular magnetic gamma-iron(III) oxide by reducing acicular alpha-iron(III) oxide to magnetite and then oxidizing it to gamma-iron(III) oxide, wherein the alpha-iron(III) oxide is treated with a water-soluble alkaline earth metal compound and an alkylphenol with one to three alkyl radicals, each of 4 to 24 carbon atoms, on the benzene nucleus. Gamma-iron(III) oxides manufactured in this way show better magnetic orientability in the binder-containing dispersion, and a higher coercive force than prior art magnetic pigments.
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公开(公告)号：DE2639250A1
公开(公告)日：1978-03-09
申请号：DE2639250
申请日：1976-09-01
Applicant: BASF AG
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公开(公告)号：DE2617809A1
公开(公告)日：1977-11-03
申请号：DE2617809
申请日：1976-04-23
Applicant: BASF AG
Inventor： SCHOENAFINGER EDUARD DIPL CHEM , MOTZ HERBERT DIPL ING DR , OHLINGER MANFRED DIPL CHEM DR , DEIGNER PAUL DR , GRAU WERNER DIPL CHEM DR
IPC: G11B5/712 , C09C1/34 , C09C3/12 , C09D5/23 , C09D7/12 , G11B5/706 , H01F1/11 , C04B35/12 , C01G37/02 , B05D5/12 , G11B5/72
Abstract: Chromium dioxide magnetic pigments are stabilized against loss of their magnetic properties by treating them, in aqueous and/or alcoholic suspension, with a block copolymer consisting of siloxane units and alkyleneoxy units of 2 to 4 carbon atoms, the alkyleneoxy units being bonded to the polysiloxane radical by a Si-O-C or Si-C group, in an amount of from 1 to 40% by weight based on the chromium dioxide, after which the latter is separated off and dried at from 50 DEG to 200 DEG C. The stabilized chromium dioxide magnetic pigments may be used for the manufacture of magnetic recording media exhibiting improved stability of the magnetic properties under adverse climatic conditions.
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公开(公告)号：DE2606832A1
公开(公告)日：1977-09-08
申请号：DE2606832
申请日：1976-02-20
Applicant: BASF AG
Inventor： JAKUSCH HELMUT DIPL PHYS DR , SAPPOK REINHARD DIPL CHEM DR , SCHOENAFINGER EDUARD DIPL CHEM , SCHNEEHAGE HANS HENNIG DIPL CH , LOEWENBERG GUSTAV DIPL ING , GRAU WERNER DIPL CHEM DR , MAHLER KARL DIPL ING DR , FALK ROLAND DIPL CHEM DR
Abstract: Magnetic recording material is prepd. by intensive mixing of needle-like magnetic pigment and a carrier liq. comprising a synthetic organic binder and a dispersing agent to a paste and subsequent drying and granulating to a free flowing pigment mixt. The pigment mixt. is conventionally mixed with a synthetic organic binder, solvent and opt. other additives to form a dispersion which is coated thinly and evenly with simultaneous alignment of the needle-like pigment onto a support and dried. The recording material has improved packing in the binder and improved alignment. In a example, Fe2O3 powder was mixed with a polyesterurethane, dried, granulated, dispersed in a vinyl chloride copolymer soln. and coated onto a PET support.
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