Basf Aktiengesellschaft

Roland Falk

Paul Deigner

Karl Uhl

Herbert Motz

Dieter Schaefer

Eberhard Koester

Werner Balz

Joachim Hack

August Lehner

Dieter Mayer

Hans-Joerg Hartmann

Peter Nagel

Peter Felleisen

Werner Grau

Rudolf Bachmann

Aribert Krug

Karl Mahler

Georg Huber

Paul Willmann

Heinrich Hartmann

Peter Rudolf

Werner Steck

Hermann Roller

Gerd Wunsch

Guenter Vaeth

Werner Loeser

Helmut Kopke

Guenter Eckert

Heinrich Wittkamp

Job-Werner Hartmann

Volker Richter

Friedrich Domas

Milan Velic

Josef Woellhaf

Werner Senkpiel

Uwe Woweries

Rudolf Sand

Dieter Scheffel

Harald Frischmann

Karl Deimling

Karl Krucker

Karl H Roemer

Peter Gawlik

Hermann Maier

A process for the preparation of a magnetic recording medium by dispersing pulverulent magnetic material in a binder mixture which is dissolved in an organic solvent and essentially consists of an elastomeric polyurethane and a high molecular weight hydroxyl-containing polymer, with addition of dispersing assistants and conventional additives, applying a layer of the dispersion, to which a diisocyanate and/or polyisocyanate has first been added, to a base material and the solidifying the layer and crosslinking the binder matrix, wherein the diisocyanate and/or polyisocyanate is added to the dispersion and, before applying the dispersion to the base, from 15 to 55% of the NCO groups present react with the hydroxyl-containing polymer of the binder mixture.

Preparation of magnetic recording media

A process for polishing the ground surfaces of magnetic storage disks which consist of a rigid substrate provided on both sides with a firmly adhering magnetic coating consisting of a magnetic material finely dispersed in an organic polymer and conventional additives, by pressing felt rings or felt disks against the moving magnetic storage disk, to the surface of which an aqueous emulsion containing butyl acetate with or without butane-1,4-diol is applied.

Process for polishing the surfaces of magnetic storage disks

Magnetic recording media possessing a thin magnetic layer are produced by dispersing finely divided magnetically anisotropic material and conventional additives in a solution of a polymeric binder in an organic solvent, applying a layer of the dispersion to a non-magnetizable base by means of a knife-coater, then, if required, orienting the magnetically anisotropic material by means of a magnetic field and drying the applied layer, a high molecular weight organic compound which acts as a thickener being added to the magnetic dispersion.

Production of magnetic recording media

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

The invention relates to magnetic recording media comprising a non-magnetic base and, applied thereto, a firmly adhering magnetic coating based on a finely divided magnetic pigment and a special binder mixture. This binder mixture consists essentially of 20 to 90 percent by weight of an elastomeric polyurethane which is soluble in a volatile organic solvent, is practically free of isocyanate groups and has been obtained from a linear, aliphatic polyester or polyether and a diisocyanate of 6 to 24 carbon atoms, and of 10 to 80 percent by weight of a vinyl chloride copolymer which contains 50 to 90 percent by weight of vinyl chloride units and 10 to 50 percent by weight of units of one or more diesters of maleic acid with an alcohol of 1 to 3 carbon atoms, or of the reaction product of this binder mixture with a polyisocyanate of 6 to 50 carbon atoms. Magnetic coatings containing such a binder mixture are distinguished by improved surface hardness coupled with improved orientability of the magnetic particles, as a result of which such recording media are particularly suitable for modern video- and audio-recording instruments.

Magnetic recording media

A magnetic recording medium comprising a non-magnetic base and a magnetizable layer which is applied to at least one side thereof and comprises magnetic particles finely dispersed in a polymeric binder and additives, the surface of the magnetizable layer being provided with a coating of a perfluoropolyether oil mixture as a lubricant.

Rigid magnetic recording disk having perfluoropolyether lubricant

Magnetic recording media comprising a non-magnetic base and, applied thereto, a firmly adhering magnetic coating based on a finely divided magnetic pigment dispersed in a binder which contains at least 50 percent by weight of a special polyurethane elastomer, namely a thermoplastic polyurethane which is soluble in tetrahydrofuran, is free from isocyanate groups and has been manufactured from (A) 1 mole of a hydroxyl-containing polyester having a molecular weight of from 700 to 2,500, (B) from 0.3 to 3 moles of a linear aliphatic diol of 2 to 10 carbon atoms, (C) from 0.05 to 0.4 mole of a triol of 3 to 10 carbon atoms, and (D) from 1.35 to 4.7 moles of a diisocyanate of 6 to 30 carbon atoms, the amount of NCO groups being approximately equivalent to the amount of OH groups of the sum of components (A) to (C).

Magnetic recording media containing elastomeric polyurethane binders in

The invention relates to an improved apparatus for the manufacture of magnetic discs carrying very thin magnetic layers, by applying a fluid dispersion of magnetic materials in a binder mixture to rigid base discs by the spin-coating process. Above the side of the base disc which is to be provided with the magnetic layer, there are arranged means which produce an aerodynamic boundary layer above the discs during rotation of the latter. This avoids the formation of surface irregularities and of coating streaks during production of the layer by spin-coating.

Apparatus for spin coating in the production of thin magnetic layers for

The invention relates to an improved process for the manufacture of magnetic discs carrying very thin magnetic layers, by applying a fluid dispersion of magnetic materials in a binder mixture to rigid base discs by the spin-coating process. Above the side of the base disc which is to be provided with the magnetic layer, there are arranged means which produce an aerodynamic boundary layer above the discs during rotation of the latter. This avoids the formation of surface irregularities and of coating streaks during production of the layer by spin-coating.

Manufacture of magnetic discs

A process for the manufacture of rigid magnetic recording media by depositing a cobalt-containing ferromagnetic metal layer on a non-magnetic metallic base disc provided with a cured layer of binder which does not dissolve or swell in organic solvents and contains non-magnetic pigments, and which has been activated, before deposition of the ferromagnetic layer, by treatment with a solution of a palladium (O) complex in an organic solvent, followed by decomposition of this complex, to prepare it to receive the ferromagnetic metal layer which is produced by electroless deposition.

Process of making a magnetic recording medium

The invention relates to a process for the manufacture of improved magnetic discs by applying a thin layer of a liquid dispersion of magnetic pigments and optionally further, non-magnetic, pigments in a binder mixture to a non-magnetic rigid base, and curing the magnetic coating which has been applied. The binder used is a mixture of polycondensates comprising 60 to 70% by weight of a solid curable polycondensate of 2,2-bis(4-hydroxyphenyl)-propane and epichlorohydrin having an epoxy equivalent weight from about 400 to 2,500 and a melting point from about 50.degree. to 150.degree. C, 10 to 30% by weight of a curable allyloxybenzene-formaldehyde condensate of the resol type with free methylol groups or with methylol groups etherified with a lower alcohol, and having a molecular weight of less than 1,000, and 10 to 30% by weight of a curable melamine-formaldehyde condensate with more than two methylol groups etherified with n-butanol or iso-butanol, and having a molecular weight of less than 2,500. A magnetic dispersion using such a binder allows the application of a firmly adhering magnetic coating, even in thicknesses of less than 4 .mu., to aluminum discs or pre-coated aluminum discs, and the magnetic coating produced has high resistance to mechanical wear.

Magnetic recording discs

A process and apparatus for producing magnetic discs in which the preferred direction of orientation of the anisotropic magnetic particles, contained in an organic binder system, is tangential to the circumference of the disc. Orientation is effected, prior to solidification of the magnetic layer, by the action of a magnetic field which is formed in the plane of symmetry between at least two pairs of magnetic poles, the poles of each pair being of the same polarity and opposite each other. One pair of poles flares out in cross section toward the plane of symmetry between the pairs of poles, whereas the other pair or pairs of poles of opposite polarity, when viewed in cross section, taper toward the said plane of symmetry to a point, the distance between the poles of such pair(s) being greater than that between the flared poles, and the plane of symmetry of the pairs of poles being in the plane of the disc. Using this process and apparatus, magnetic discs with a non-magnetic metallic base are obtained, in which the anisotropic magnetic particles in the layer of fluid binder applied to the base are oriented tangentially to the circumference of the disc during spin-coating.

Device for the magnetic orientation of magnetic recording media

A disk to be coated on both sides in rotatively supported within an annular housing of a larger internal diameter. Means traverse and coat each side of the rotating disk. The inner housing wall is disposed transversely to the disk and has an annular slot operatively associated with the disk whereby excess coating material is spun off the disk and into the housing. The housing is radially of a triangular cross-section, the apex offset from said disk whereby said spun off material strikes an inclined internal wall surface of the housing. Means orbit a plurality of such disks about a central axis and through a plurality of movable treating stations.

Apparatus for coating magnetic disks

A high-speed roller system for transporting webs of sheeting, preferably for coating the same with a magnetic layer, comprising a suction roller for control of the speed of the web, which suction roller has a surface containing grooves, preferably rhombic grooves, in which the perforations for sucking the sheeting are disposed, preferably at the points of intersection, the ratio of the total cross-sectional area of the perforations to the total surface area of the roller being from 0.7 to 3%.

Roller system for continuous transport of webs of sheeting

A device for manufacturing magnetic recording media in which the magnetic particles in the recording layer are oriented in a preferred direction, the fluid coating applied to the base being subjected to the action of a magnetic field produced in the air gaps between the spaced apart poles of two magnetic circuits, one on each side of the coated face, arranged symmetrically with respect to the plane of the coated base, the edges of the poles adjacent to the coated base terminating in screening elements shaped in such a way that the distance between the surfaces of the screening elements facing the coated base and the coated base itself increases as the screening elements extend away from the edges of the poles. A high degree of magnetic anisotropy in the recording layer can also be obtained when the magnetic circuits are at a relatively large distance from the still fluid magnetic coating.

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Achern, Germany

Roland Falk