Abstract: Magnetic recording media comprise a non-magnetic base which is provided with a magnetic layer which consists of a dispersion of an anisotropic magnetic material in an organic binder which consists essentially of an OH-containing polyurea-urethane binder crosslinked with polyisocyanate. The OH-containing polyurea-urethane is obtained by reacting a polydiol, a diol and a primary or secondary aminoalcohol, and if appropriate a triol, with a diisocyanate.

Abstract: 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) an OH-containing polyurethane which is crosslinked with polyisocyanates, (2) a high molecular weight thermoplastic linear polyurethane and (3) a polyvinylformal binder, a phenoxy resin, a cellulose ester or a vinyl chloride copolymer.

Abstract: Magnetic recording media comprising a non-magnetic base which is provided with a magnetic layer which consists essentially of a dispersion of an anisotropic magnetic material in a mixture of an OH-containing polyurea-urethane binder, which is crosslinked with a polyisocyanate, with a physically drying binder.

Abstract: 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.

Abstract: Magnetic recording media comprise a non-magnetic base and one or more magnetic layers consisting of an organic binder matrix containing finely divided magnetic material, the said matrix being obtained by electron beam curing of a mixture of from 70 to 90% by weight of a polyurethane acrylate polymer possessing polymerizable double bonds and from 10 to 30% by weight of one or more copolymerizable compounds.

Abstract: Magnetic recording media comprise a non-magnetic base and one or more magnetic layers consisting of an organic binder matrix containing finely divided magnetic material, the said matrix being obtained by electron beam curing of a mixture of from 50 to 100% by weight of a polyurethane acrylate polymer possessing polymerizable double bonds and from 0 to 50% by weight of an acrylate and/or an acrylate prepolymer and/or an N-vinyl monomer and/or an N-vinyl prepolymer.

Abstract: A tape cassette, in particular a video cassette, comprises two flanged reels and, between the flanges of each reel, a spring member as a biassing means to prevent the tape from slipping off the roll or folding over. The spring members can be attached to the side walls or rear wall of the housing, and their free ends constantly bear against the peripheries of the tape rolls. In specific embodiment the spring member advantageously includes the braking spring for a reel-braking device. By using a conductive material on one or both sides of the spring member and appropriately arranging the spring member relative to a tape guide element or to an element grounded on the tape recorder, it is possible to directly prevent tape loop formation, which is a cause of tape slippage and folding-over. Moreover, tape winding and unwinding are improved.

Abstract: 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.

Abstract: Magnetic recording media which have a thin backing coating and consist of a non-magnetic flexible base and a magnetic layer which is applied to one side of the base and comprises magnetic material finely dispersed in an organic binder are produced by applying a dispersion of finely divided non-magnetizable conductive and non-conductive solids and conventional additives in a solution of a polymeric binder in an organic solvent to that side of the base which is opposite the magnetic layer by means of a knife-coater, and then drying the layer, a high molecular weight organic compound which acts as a thickener being added to the backing coating dispersion.

Abstract: Magnetic recording media are produced by dispersing timely divided anisotropic magnetic material in a polymeric binder to a non-magnetizable base.

Abstract: 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.

Abstract: 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.

Abstract: Ferromagnetic metal particles, consisting essentially of iron and comprising a core, containing not less than 85% by weight of metallic iron, and an iron oxide plus chromium oxide surface layer surrounding this core, which layer additionally contains one or more elements selected from the group comprising zinc, phosphorus in the form of phosphate, aluminum, calcium, strontium, barium, cadmium, lead, cobalt and nickel in a total amount of not more than 9.5% by weight, based on the total amount of the metal particles, and a process for the production of such particles.

Abstract: Magnetic recording media comprising a non-magnetic base and, applied thereto, one or more magnetizable layers based on an anisotropic magnetic material finely dispersed in an organic binder containing an ionomeric polyurethane elastomer, wherein the binder used is a substantially aqueous polyurethane dispersion prepared from a polyurethane solution which has been obtained by reacting a polyisocyanate with an organic polyhydroxy compound in the presence of an organic solvent that is inert to isocyanate groups.

Abstract: A process for the manufacture of magnetic recording media, comprising a non-magnetic base and, applied thereto, one or more magnetizable layers, consisting of an anisotropic magnetic material finely dispersed in an organic binder, wherein the binder contains at least 40% of an aqueous ionomeric polyurethane dispersion which at 50.degree. C. forms films having a modulus of elasticity of from 50 to 700 N/mm.sup.2 and a DIN No. 53,157 pendulum hardness of from 20 to 110 s, the corresponding values of the modulus and hardness at room temperature being more than 3.5 times higher.

Abstract: 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.

Abstract: 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.

Abstract: 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.