Abstract: Polymeric materials (I) are obtainable by reacting1. a polymer II comprisinga) from 80 to almost 100 mol % of a C.sub.1 -C.sub.25 -alkyl ester of an .alpha.,.beta.-unsaturated carboxylic acid,b) from 0 to 20 mol % of a further monomer,c) tetrahydrofuran hydroperoxide as polymerization initiator and, if required,d) a further polymerization initiator and/or regulator by means of which the majority of the polymer chains of the polymer II are terminated at one of their ends by a hydroxyl group,2. with a polyfunctional isocyanate III to give a reaction product IV, the amount of isocyanate groups being from 1.2 to 3.0 mol per mol of hydroxyl groups of II, and3. reacting IV with ammonia or with a compound V which has an amino function reactive toward isocyanates.The polymeric materials can be used as dispersing resins for pigment-containing coatings, in particular for the production of magnetic recording materials.

Abstract: In magnetic recording media consisting of a nonmagnetic substrate and at least one magnetizable layer firmly applied thereon and based on magnetic material dispersed in a binder mixture which contains at least one hydroxyl-containing, preferably low molecular weight polyureaurethane and one polyurethaneurea (meth)acrylate, the polyurethaneurea (meth)acrylate is obtained by reacting a poly(meth)acrylate having up to 2 terminal OH groups per mol and a molecular weight of from 200 to 50,000 with a mixture of aliphatic polyisocyanates having an average functionality of from 3.0 to 6.0 NCO groups per mol, consisting offrom 0.1 to 10% by weight of a diisocyanate, from 30 to 80% by weight of a triisocyanate and from 20 to 60% by weight of an isocyanate having a functionality of from 4 to 10, with the proviso that from 1.2 to 3.

Abstract: The invention relates to parallelepipedal packaging containers for recording media in tape form which are wound up onto hubs provided with internal bores and are stacked one on top of the other, comprising a bottom part, a top part and side parts, which are joined to one another by means of molded-on film hinges, and it being possible for a hub support to be pushed through the internal bores of the hubs.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and at least one magnetizable layer bonded thereon and based on a magnetic material dispersed in at least one polyurethane and one polyurethaneurea (meth)acrylate, the polyurethaneurea (meth)acrylate being obtained by reacting a hydroxyl-containing poly(meth)acrylate with a mixture of di- and polyisocyanates and converting the remaining NCO groups with ammonia or primary or secondary amines into urea groups.

Abstract: Sheet-like polyethylene terephthalate materials having slight surface roughness consisting of dendritic, plateau-like structures having a fissured, fractal edge, a process for their preparation by exposing the surfaces to UV radiation produced by the decomposition of excimers, and the use of polyethylene terephthalate films treated in this manner as a substrate for ferromagnetic thin metal layers.

Abstract: Magnetic recording media are obtained by preparing a dispersion of anisotropic magnetic material and additives in a solution of a polymeric binder in an organic solvent, applying the dispersion as a layer to a nonmagnetizable substrate, then orienting the anisotropic magnetic material in a magnetic field and solidifying the applied magnetic layer, and the magnetic layer contains water-repellent polysilica and, if required, a highly viscous polysiloxane.

Abstract: An apparatus for the separating and renewed applying of an incoming material web on winding machines to a winding sleeve, a separating knife and an applying brush, fixedly connected to the latter, being swivelled into the path of the material web for separating, and the separating knife being accelerated by a hydraulically driven motor, controlled by a stepping control motor, by means of a shaft at an angle of up to 130.degree., whereupon the separating operation is performed at from 230.degree. to 260.degree. and the shaft comes to a standstill again after about a further 90.degree.. In this way, transverse separating of a material web is possible even at high speeds. In order to avoid deformations of the separating knife, the shaft of the hydraulic motor is provided with a compensating shaft.

Abstract: A ring part and individual winding hub combination comprises a single-flange ring part with or without spring elements on the receiving circumference for the internal bore of the associated winding hub, which has or does not have spring elements between the internal bore and outer circumference. Receiving circumferential rim and internal bore may expediently be designed with intermeshing toothings.

Abstract: A cleaning cassette for magnetic heads in a cassette drive includes at least one container with cleaning fluid, comprising an at least partially flexible hollow body, at least one valve device and at least one feed channel for the cleaning fluid to the cleaning device. The cleaning system can be used for tape cassettes and disk cassettes with magnetic medium.

Abstract: A thin metal layer is applied in a thickness of less than 1,000 nm to a polymeric, web-like substrate which is moved along a cylindrical support in a vacuum chamber containing an evaporator crucible releasing the metal vapor toward the support and two coating screens arranged between the evaporator crucible and the support and defining the limiting angles of incidence of the vapor jet striking the substrate, by a process in which, in the case of predetermined limiting angles of incidence, the amount of metal vapor applied to the substrate can be optimized by means of the arrangement of the coating screens and the position of the evaporator crucible.

Abstract: Semicrystalline polymers are heat-sealed with metals under pressure and at a temperature between the glass transition temperature and the softening temperature of the polymer by prior exposure of the polymer surface to UV radiation produced by the decomposition of excimers in the wavelength range of from 120 to 400 nm and with an energy density below the ablation threshold.

Abstract: A container for a tape cassette of approximately parallelepiped form having an elevated head part is formed with a bottom wall and a lid wall which can move with respect to each other by means of hinge devices. In this arrangement, if appropriate, one of said walls is provided with a pocket for receiving the elevated head part and has a decreasing wall thickness along its transverse axis from its outer longitudinal edge in the direction of the axis of the hinge devices or of the pocket. The other wall may likewise have a wall thickness decreasing in the same direction. The inner face of the wall provided with the pocket may also be arranged parallel, at least with respect to the inner face of the front wall of the pocket. The container can be used advantageously for any cassette of the type more precisely specified above for audio, video and/or data recording, since a minimal overall height of the container is achieved with minimal use of material.

Abstract: An apparatus for checking deep-frozen food, which irreversibly indicates if an additional storage temperature has been exceeded, is described. A flat plastic bag having transparent walls, into which eutectic mixture having a liquid/solid phase transition in the range from 0.degree. to -50.degree. C. has been introduced, together with a magnetic dispersion consisting of finely divided magnetic pigments, has a heat-conducting connection to the material to be frozen. A magnetic stripe which contains a magnetically recorded pattern and which remains connected to the bag until the indicating apparatus together with the material to be frozen has been cooled below the limiting temperature is stuck to the bag. The magnetic stripe is then removed. If the permissible limiting temperature is exceeded, the optically or magnetically readable structure produced by the magnetic stripe in the indicator bag is eliminated, permitting easy checking of the deep-frozen food.

Abstract: Acicular cobalt-containing magnetic iron oxides having a high coercive force and a core/shell structure and hence low temperature dependence of the coercive force are prepared by a process in which, in a first stage, surface activation is effected by means of iron(II) and cobalt ions under alkaline conditions on the iron oxide core under an inert gas atmosphere and thereafter, in a second stage, an epitactic coating of cobalt ferrite is applied, which coating is formed oxidatively from iron (II) and cobalt (II) hydroxide, likewise under alkaline reaction conditions. The total amount of cobalt ions used for doping remains unchanged compared with the known doped iron oxides or is even smaller. In the second process stage, the achievable coercive force can be controlled by the proportion of air in the gas mixture during the formation of the epitactic coating.

Abstract: A cassette with a recording medium, in particular a magnetic recording medium, is designed with a displaceable identification part which can be pushed into the cassette housing. For this purpose, a web is provided behind a cassette opening in a cassette wall, which web runs at an angle with respect to the cassette wall. It is also possible to provide a web which is approximately parallel to the cassette wall, and the identification part, designed as a slide, is provided with a front beveling, in the opening sliding direction, in order to push the slide partially past the edge of the cassette wall located in the opening direction. The cassette can be used for recording/reproducing signals of any type, and any functions of the associated cassette apparatus can be controlled indirectly by the positionally displaceable identification part.

Abstract: A pressure device for recording media in tape form, in particular magnetic tapes, has at least one pressure element and comprises a support element. When the device is actuated by the head coming to bear, a deflection of the device takes place, and a pressing against the recording medium is effected automatically by at least one extension of the support element, this pressing ending automatically when the head is no longer in bearing contact. The bearing pressure may take place directly on the tape rear side or tape front side, or else indirectly on the tape front side or the tape rear side or both sides simultaneously. Pressing and/or antifriction and/or cleaning elements may also be arranged, at least partially, fixed in place with respect to the tape. The invention can be used in the case of all cassettes, film and magnetic-tape systems.

Abstract: A winding device for magnetic tapes, in which the incoming tape (1) is guided over tape-deflecting and guiding elements (3, 4) to the tape roll (7) for winding up, a rubber roller (5) fastened to a low-mass swing arm (6) being pressed against the tape at the point at which the tape tangentially reaches the tape roll, and both the swing arm and the tape-deflecting elements being seated on a pivotal guide arm, which is guided by a pneumatic guidance according to the structure of the tape roll. In this way, a satisfactory winding profile is achieved in the case of magnetic tapes to be wound up, even at high winding speeds.

Abstract: A material suitable as crosslinking binder component for pigment-containing coatings and having an average molecular weight of from 25,000 to 150,000, obtainable by reacting a polyurethane comprising a diol having a molecular weight between 400 and 4,000, an aliphatic or cycloaliphatic diol of 2-18 carbon atoms, an aromatic diol of 8-36 carbon atoms, a trihydric or polyhydric alcohol of 3-18 carbon atoms, a polyhydric alcohol of 3-40 carbon atoms containing a tertiary amino group, and a diisocyanate of 3-34 carbon atoms with a compound containing one or more hydroxyl groups and one or more amino groups reactive toward isocyanate groups. The materials may be used as crosslinkable binder components for pigment-containing coatings, in particular for the production of magnetic recording materials.

Abstract: A wet-on-wet application process by means of a sheet extruder having at least two slot dies is described, the upper layer containing metal powders and/or metal powder alloys while the lower layer contains the same magnetic pigments and conductivity-increasing and/or transparency-reducing additives, preferably carbon black, and both layers having virtually the same rheological properties. The magnetic recording medium has improved conductivity and very good running behavior, in particular when used as a mirror mastertape.

Abstract: A magnetic recording medium comprises a nonmagnetic substrate and at least one ferromagnetic metal layer applied thereon and a protective layer formed on this metal layer and consisting of a compound which consists of an unfluorinated or partially fluorinated alkyl radical and a disulfide, hydroxyl or keto group.