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

IPC: C01G49/06 ,  G11B5/706 ,  H01F1/10 ,  H01F1/11 ,  C09C1/24

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.

公开(公告)号：DE2536535A1

公开(公告)日：1977-02-24

申请号：DE2536535

申请日：1975-08-16

Applicant: BASF AG

Inventor： OHLINGER MANFRED DIPL CHEM DR ,  WAGNER GERHARD DIPL ING ,  HONECKER GERHARD DIPL ING ,  STRITZINGER HEINZ DIPL ING ,  SPAEHN HEINZ DIPL ING

IPC: C01G37/00 ,  B01J19/02 ,  C01G37/027 ,  C23F11/04 ,  C23F11/18

Abstract: In order to reduce corrosion of the inside walls of a reactor made of iron or an iron alloy and used for the synthesis of chromium dioxide by hydrothermal conversion of chromium(VI) oxide with chromium oxides of lower valency, lead or bismuth is added at those points of the reactor at which an aqueous phase occurs during conversion and which do not contact the chromium oxides to be converted. The lead or bismuth may be used in metallic form or in the form of their oxides, hydroxides or salts.

公开(公告)号：DE2501902A1

公开(公告)日：1976-07-22

申请号：DE2501902

申请日：1975-01-18

Applicant: BASF AG

Inventor： PISTER PHILIPP ,  OHLINGER MANFRED DIPL CHEM DR ,  STRITZINGER HEINZ DIPL ING ,  HARTMANN JOB-WERNER DIPL CHEM ,  WETTSTEIN EUGEN

IPC: C09C1/24 ,  C09C1/34 ,  C09C3/00 ,  G11B5/706 ,  C09C3/10 ,  G11B5/68

Abstract: Process for improving the dispersibility of needle-shaped magnet oxide pigments used for magnetic recording carriers, by washing the pigment in an aq. medium, filtering and drying. The washing water contains, by wt. 0.1-10% of a polymerised, organic, water-soluble or at least water-miscible, surfactant, and is used at 30-95 degrees C. The wash water pref. contains 4-8% of the surfactant and is used at 85-95 degrees C. the pref. surfactants being an melamine-formaldehyde condensn. product and/or a phthalic acid-polyol reaction product and/or a ricinoleic acid-maleic anhydride product, with mol.wt. 300-400. The pigment is pref. gamma Fe2O3. The magnetic recording tape obtd. has reducted direct current noise and lower harmonic distortion.

公开(公告)号：DE2461936A1

公开(公告)日：1976-07-08

申请号：DE2461936

申请日：1974-12-31

Applicant: BASF AG

Inventor： PISTER PHILIPP ,  BUETTNER FRANZ ,  OHLINGER MANFRED DIPL CHEM DR ,  STRITZINGER HEINZ DIPL ING ,  HARTMANN JOB-WERNER DIPL CHEM ,  SCHNEIDER WALTER ,  HAMMON FRITZ

IPC: C09D5/23 ,  C09D7/12 ,  G11B5/716 ,  G11B5/68 ,  B05D5/12 ,  H01F10/02

公开(公告)号：DE2456960A1

公开(公告)日：1976-06-16

申请号：DE2456960

申请日：1974-12-03

Applicant: BASF AG

Inventor： HAMMON FRITZ ,  OHLINGER MANFRED DR ,  STRITZINGER HEINZ DIPL ING ,  HARTMANN JOB-WERNER DR

IPC: G11B5/716 ,  G11B5/70 ,  H01F10/00

Abstract: A laminated magnetogram carrier, consisting of a substrate with >=2 magnetic layers contg. an acicular magnetic material in an organic binder system, has a toper layer contg. a magnetic pigment with a high static signal-to-noise voltage ratio (S/N) pref. over 61.0 dB whilst the S/N is lower pref. below 61.0 dB for the pigment in the lower layer the coercivity of the materials differing by a max. of +10%. Flexible magnetogram carriers satisfying high requirements w.r.t. static noise are obtd. without the exclusive use of pigments with the required S/N value.

公开(公告)号：DE2242499A1

公开(公告)日：1974-03-07

申请号：DE2242499

申请日：1972-08-30

Applicant: BASF AG

Inventor： HARTMANN JOB WERNER DR ,  HARTMANN HANS JOERG DR ,  ROLLER HERMANN ,  STRITZINGER HEINZ DIPL ING ,  FALK ROLAND DR

IPC: C09D5/23 ,  G11B5/702 ,  G11B5/738 ,  G11B5/68

Abstract: 1445152 Magnetic coating BASF AG 29 Aug 1973 [30 Aug 1972] 40667/73 Heading B2E A flexible magnetic recording media is produced 'by applying a 0.05-1.5 microns thick intermediate coating to a dimensionally stable plastics film which acts as base and subsequently applying a layer of a fluid magnetic dispersion consisting of a finely divided magnetically anisolbropic magnetic pigment, an organic binder which does not cross-link during the dispersion of the magnetic pigment, is free from isocyanate groups and is dissolved in a volatile organic solvent which does not react with isocyanate groups and, optionally a dispersing agent and other conventional additives, orienting the magnetic particles in a magnetic field, drying the magnetic coating and optionally subjecting the magnetic coating to a surface treatment, the intermediate coating comprising a vinylidene chloride copolymer which does not react with isocyanate groups containing 5-70% by weight of a scluble polyisocyanate, and the binder and/or dispersing agent for the magnetic coating containing groups which react with isocyanate groups. The base may be polyethylene terephthalate film. Suitable vinylidene chloride copolymers are copolymers containing at least 70% of vinylidene chloride units, and suitable comonomers are methyl methacrylate, dimethyl maleate, methacrylonitrile and especially acrylonitrile. The magnetic pigments in the magnetic coating may be gamma-iron oxide, magnetite, ferromagnetic chromium dioxide, fenromagnetic metals and metal alloys. Suitable binders for the magnetic coating are vinyl chloride-vinyl ester copolymers, vinylidene chloride-acrylonitrile copolymers, copolyamides, soluble thermoplastic polyester-urethanes, polyvinyl formals and mixtures thereof. Hydroxyl groups or other groups which react with isocyanate groups may be provided in the binder by using copolymers of 50-80% vinyl chloride and 20-50% vinyl esters into which 4-20% by weight of vinyl alcohol units have been introduced by partial hydrolysis. Dispersing agents having groups that react with isocyanate groups mentioned are oleic ethanolamide, isostearic acid, stearic acid, oleic acid, lecithin. Other additives mentioned are lubricants, e.g. metal soaps, fatty acids, waxes, silicon oils, conductive carbon, talc, silicates. The oriented and dried magnetic coatings may be calendered and the coating webs then slit in the longitudinal direction.