Basf Aktiengesellschaft

Basf Magnetics Gmbh

Dynamit Nobel Aktiengesellschaft

Basf Corporation

Emtec Magnetics Gmbh

Basf Aktiengsellschaft

Manfred Ohlinger

Werner Steck

Helmut Jakusch

Peter Rudolf

Eberhard Koester

Guenter Vaeth

Eduard Schoenafinger

Werner Loeser

Wilhelm Sarnecki

Norbert Mueller

Heinz Stritzinger

Ekkehard Schwab

Jenoe Kovacs

Paul Deigner

Christof Jaeckh

Fritz Hammon

Horst Autzen

Rudi Lehnert

Claus-Dietrich Seiler

Laszlo Marosi

Helmut Auweter

Heinz Nestler

Werner Grau

Rainer Feser

Hans Henning Schneehage

Ronald J Veitch

Job-Werner Hartmann

Harald Jachow

Walter Schneider

Otto Ambros

Eugen Wettstein

Rudolf Brodt

Gerald Neubauer

Jurgen Amort

Milena Melzer

Michael W Mueller

Gerhard Frank

Werner Huebner

Manfred Steuerwald

Hans J Wilfinger

Paul Duffner

Emil Pfannebecker

Eduard Schonafinger

Gerhard Honecker

August Lehner

Werner Lenz

Albert Kohl

Norbert Schneider

Herbert Motz

Peter Heilmann

Michael Bobrich

Dieter Schaefer

Helmut Kopke

Volker Koch

Norbert Muller

Eckhard Hetzel

Hermann Dikow

Werner Stumpfi

Reinhard Polke

Gerhard Wagner

Reinhard Koerner

Hans-Juergen Becker

Bernhard Boettcher

Erich Hoffmann

Helmut Reinicke

Joachim Werther

Friedrich R Faulhaber

Hans H Reich

Hans Reichert

Georg Schnell

Juergen Amort

Werner H&uuml;bner

Philipp Pister

Franz Buettner

Bernhard Bottcher

Werner Hubner

Hansjoerg Siegle

Eberhard Koster

Werner Loser

Gunter Schadel

Gunter Vath

Reinhard K Orner

Bernd H Oppner

Dieter Schwarz

Wolfgang Guth

Horst Grosselfinger

Heinz Spaehn

Described are tape-type magnetic recording media (I) including a non-magnetic substrate (III), at least one film applied to the substrate and, in at least one of these films, an inorganic acicular pigment (II) suitable for use as a supporting pigment, the ratio of the mean length to the mean diameter of the pigment (II) being at least 3 and the mean modulus of elasticity of the films being not less than 15 GPa in the longitudinal direction of the tape-type recording medium (I).

Magnetic recording media

A finely divided acicular CrO.sub.2 modified with iron, tellurium and/or antimony and having a high coercive force possesses improved heat stability of the residual induction and a relatively narrow distribution of the particle size and of the coercive force. This CrO.sub.2 pigment is obtained by a method in which the iron compound used for the modification is iron oxalate, which is employed in an amount of 1-10% by weight, based on the theoretical CrO.sub.2 yield.

Finely divided acicular magnetic modified chromium dioxide

A transfer film having a magnetic layer consists essentially of a substrate film, a parting layer and a transfer layer which is detachable from the said parting layer and is formed by one or more magnetic layers, and, on that side of the magnetic layer which faces the substrate film, after detachment of the substrate film, the surface-forming layer consists of a top layer which contains inorganic pigments in a cross-linked polymer matrix and has a thickness of from 0.2 to 5.0 .mu.m and a surface resistance of from 10.sup.-1 to 10.sup.-8 ohm/cm.

Transfer film with magnetic layer

A magnetic recording medium comprising a nonmagnetic substrate and at least one magnetic layer applied thereon and containing an acicular chromium dioxide uniformly distributed in a polymeric binder and additives and having a coercive force of at least 60 kA/m, a mean particle length of the chromium dioxide of less than 300 nm, whose factor HD according to the formula ##EQU1## where KT is the coercive force of the magnetic layer in [kA/m], measured in an external field of 380 kA/m, L is the mean particle length and .DELTA.L is the range of the particle size distribution, determined from the numerical distribution of the particle length, both measured in [nm], is greater than 1.85, and a process for the preparation of this chromium dioxide.

Process for preparing modified chromium dioxide

Transfer films consist essentially of a support film, a release layer and a transfer layer detachable from this release layer and composed of two magnetic layers and said transfer films may have, on the second magnetic layer, an adhesive layer which serves for fixing the transfer layer to a substrate, the two magnetic layers each containing a magnetizable material having a different coercive force.

Transfer film having magnetic layers

Abstract of the Disclosure: Magnetic recording media comprise a nonmagnetic substrate and a magnetizable layer arranged thereon and essentially consisting of a magnetic material from the group consisting of the cobalt-modified iron oxides and of the hexagonal ferrites and inorganic fillers finely dispersed in organic binders, the inorganic filler used being ferromagnetic chromium dioxide.

Stabilized acicular ferromagnetic chromium dioxide is prepared by a method in which the chromium dioxide surface formed as a result of a reductive treatment is treated with adsorbed monobasic or polybasic hydroxycarboxylic acids.

Preparation of stabilized acicular ferromagnetic chromium dioxide

A chromium dioxide material consisting of acicular, ferromagnetic chromium dioxide particles having a nonmagnetic, hydrogen-containing protective surface layer, which material has improved stability to chemical decomposition, a process for its preparation and magnetic recording media containing this chromium dioxide and having good long-term stability of the residual magnetization under conditions of high humidity and temperature are described.

Chromium dioxide material, its preparation and magnetic recording media

An acicular, ferromagnetic material which has a high coercive force and essentially consists of iron-containing chromium dioxide is prepared by thermal decomposition of hydrated chromium(III) chromate under superatmospheric pressure.

Process for preparing acicular ferromagnetic material consisting

A process for the preparation of chromium(III) oxide by decomposing hydrated ammonium dichromate at elevated temperatures, an apparatus for carrying out this process and the use of the chromium(III) oxide thus prepared as a starting material for the synthesis of chromium dioxide.

Preparation of chromium(III) oxide

Ferromagnetic chromium dioxide is prepared by converting oxides of trivalent and hexavalent chromium under superatmospheric pressure and at elevated temperatures in the presence of water and with the addition of an antimony compound as a modifier and, if required, further additives in an amount of not more than 15% by weight, by a method in which the antimony compound is present in the form of a water-soluble salt whose anion contains one or more organic molecular moieties which are oxidized in concentrated chromic acid.

Preparation of ferromagnetic chromium dioxide

A magnetic dispersion which can be applied to a non-magnetic base to produce a recording medium is prepared by dispersing a magnetically anisotropic material in a polymer binder and in an organic solvent by a method wherein the magnetically anisotropic material is worked in a jet mill before and/or during dispersing.

Preparation of a magnetic dispersion

Molded iron catalysts which contain metallic iron particles, obtained from anisometric iron oxide particles by contact with hydrogen at .ltoreq.500.degree. C., and a lubricant, are prepared.

Molded iron catalyst and its preparation

A process for the preparation of acicular ferrimagnetic iron oxides by reducing gamma-iron(III) oxide hydroxide to magnetite, at from 280.degree. to 620.degree. C., by means of an organic compound which is decomposable at this temperature in the presence of iron oxide, and, optionally, a stream of reducing gas, and, if desired, then oxidizing the magnetite with oxygen-containing gases, at from 150.degree. to 450.degree. C., to acicular ferrimagnetic iron oxide of the formula FeO.sub.x, where x is from above 1.33 to 1.50, wherein the organic compound used for the reduction is a non-polar glycerol ester of a fatty acid which is introduced into the aqueous reaction suspension during the preparation of the gamma-iron(III) oxide hydroxide.

Preparation of acicular, ferrimagnetic iron oxides

Saturated primary amines are prepared by reacting a nitrile with hydrogen at elevated temperature under superatmospheric pressure in the presence of ammonia and a metallic iron catalyst which has been obtained by reducing anisometric iron oxide particles with hydrogen at not more than 500.degree. C.

Preparation of primary amines

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Frankenthal, Germany

Manfred Ohlinger