Basf Aktiengesellschaft

Badische Anilin- & Soda-fabrik Aktiengesellschaft

Eberhard Koester

Paul Deigner

Werner Steck

Manfred Ohlinger

Gerd Wunsch

Karl Uhl

Eduard Schoenafinger

Helmut Jakusch

Dieter Mayer

Roland Falk

Werner Loeser

Dieter Schaefer

Hans Henning Schneehage

Peter Rudolf

Werner Balz

Werner Grau

Wilhelm Sarnecki

Milena Melzer

Klaus Schoettle

August Lehner

Norbert Schneider

Christof Jaeckh

Peter Felleisen

Werner Stumpfi

Rudolf Brodt

Peter Neumann

Ernst Schefczik

Albert Kohl

Helmut Barzynski

Joachim Hack

Herbert Motz

Guenter Vaeth

Helmut Kopke

Matthias Dust

Dietmar Pfefferkorn

Friedrich Domas

Friedrich Sommermann

Manfred Steuerwald

Norbert Kreimes

Roland Koenig

Heidi Benthack-Thoms

Klaus-Dieter Schomann

Eckhart Kneller

Matthias Schwarzmann

Claus-Dietrich Seiler

Heinz Nestler

Hermann Roller

Harald Kuppelmaier

Bozidar Pavelka

Peter Dobler

Job-Werner Hartmann

Dieter Gaiser

Heinz Stritzinger

Helmut Lewin

Peter Nagel

Werner Wagner

Werner Huebner

Horst Autzen

Werner Senkpiel

Otto Ambros

Hans-Juergen Becker

Friedrich Guenther

Herbert Wagner

Wilhelmus Andriessen

Georg Huber

Karl-Juergen Reimer

Ernst Ricker

Harald Kupplemaier

Gerhard Nerschbach

Dieter Graw

Henning Schneehage

Juergen Amort

Hans Hauser

Naphtholactam dyes of the formula ##STR1## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, n, p, Z.sup.1, Z.sup.2 and the rings A, B, C and D each have the meanings stated in the description, and an optical recording medium which contains one or more naphtholactam dyes and may contain a base.

Naphtholactam dyes and optical recording medium containing these dyes

Naphtholactam dyes and optical recording medium containing these days

In magnetic recording media consisting of a non-magnetic base and, bonded on top of this, one or more magnetizable layers based on magnetic material finely dispersed in a polymer binder, a lubricant and further conventional additives, the lubricant used is a triethanolamine esterified with oleic acid.

Magnetic recording media

A tape cassette comprising at least one print-through echo-erasing device in the form of at least one appropriately shaped magnetic member made of permanent magnet material which is conveniently arranged on a tape guide element or near the apertures in the front wall of the cassette housing for the admission of scanning means. Such echo-erasing device can be used with advantage in any kind of magnetic tape cassette or cassette containing a recording medium having at least one magnetic track.

Tape cassette containing echo-erasing means

Magnetic recording media comprise a non-magnetic base which is provided with a magnetic layer consisting of finely divided anisotropic magnetic material which is dispersible in binders and additives, the binder being a mixture of (1) a high molecular weight thermoplastic linear polyurethane, (2) a polyvinylformal binder, a phenoxy resin, a cellulose ester or a vinyl chloride copolymer and (3) an OH-containing polyurethane which is crosslinked with polyisocyanates.

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

Magnetic recording media are produced by dispersing finely divided anisotropic magnetic material and conventional additives in a solution of a polymeric binder in an organic solvent, or in an aqueous dispersion of a polymeric binder, adding a polymer based on hydrophilic ethylenically unsaturated compounds to the magnetic dispersion, applying a layer of the dispersion to a non-magnetizable base, orienting the anisotropic magnetic material in a magentic field and drying the applied layer.

Production of magnetic recording media

A cassette system for any type of recording medium in strip or tape form, such as films and magnetic tapes, consists essentially of a housing whose external dimensions match those of a conventional type of cassette, and a protective holder for the recording medium which is wound into at least one roll. The housing and the holder are separate or separable members and can be fitted together. Both are provided with means for inserting the holder into the housing in the correct position, and for introducing the recording medium into the transport apparatus. The housing is provided with opening and closing means. The holder can be designed to be separable from the roll of recording medium. Preferably, the housing is a precision-made article and the holder a low-cost article.

Magnetic tape cassette arrangements

A process for authenticating recording media which are to be safeguarded against falsification and which possess a layer of exchange-anisotropic magnetic material, by determining the residual recording which is left over, because of the exchange anisotropy of the magnetic material, from a recording of a sequence of signals after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, and an apparatus for carrying out the said process.

Document identification employing exchange-anisotropic magnetic material

Magnetic recording media are produced by a method wherein a fluid dispersion of finely divided magnetically anisotropic material in a film-forming binder mixture containing a polyurethane (obtained from a polyester which possesses free hydroxyl groups, and a di- or polyisocyanate) is applied to a non-magnetic base and the magnetic layer is then hardened.

A magnetic recording disk comprising a non-magnetic substrate and two or more firmly adhering magnetizable layers applied to one or both sides thereof, the layer located directly on the substrate being magnetically isotropic, while the second layer and any additional layers exhibit orientation of the anisotropic magnetic particles parallel to the substrate and to the envisaged recording direction.

Magnetic recording disk

A process for stabilizing pyrophoric acicular metal particles consisting essentially of iron, by reaction with oxygen-containing gases in two stages, wherein, in the first stage, up to 1/3 of the passivating layer present in the final state is formed at from 25.degree. to 45.degree. C. and, in a subsequent second stage, the remainder of the passivating layer is formed at from 50.degree. to 70.degree. C.

Stabilization of pyrophoric ferromagnetic acicular metal particles

A magnetic recording medium comprising a non-magnetic base which is dimensionally stable at up to 300.degree. C., and an 0.03-0.4 .mu.m thick magnetically hard recording layer of an Sm-Co alloy, vacuum-deposited thereon, which layer possesses uniaxial magnetic anisotropy in the plane of the layer, and a process for the manufacture of this recording medium.

Magnetic recording medium and its manufacture

A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.

Document authentication by means of exchange-anisotropic magnetic

A device for magnetically orienting the magnetizable particles of magnetic recording media in a preferred direction, which media are obtained by applying a coating of anisotropically magnetic particles finely dispersed in a solution of an organic binder system and conventional additives to a non-magnetic base, and subsequently solidifying the coating, by the action, on the still fluid coating, of the magnetic fields produced by two E-shaped electromagnets arranged symmetrically with respect to, and in mirror-image relationship to, the plane of the said coating.

Device for magnetically orienting the magnetizable particles or magnetic

Growing community of inventors

Frankenthal, Germany

Eberhard Koester