Abstract: A UV-curable binder composition, a coating material which contains such a binder composition, a photoiniator mixture suitable for use in these coating materials, and a magnetic recording medium which contains such a UV-curable coating material are described.

Abstract: The thermoplastic, isocyanate-free polyurethane which contains acidic groups, is soluble in tetrahydrofuran, has a molecular weight of from 15,000 to 70,000 and is composed ofA) 1 mol of a polyol having a molecular weight of from 400 to 4000,B) from 0.3 to 9 mol of a mixture ofB1) if required, a diol of 2 to 18 carbon atoms andB2) from 0.03 to 0.4 mol of a diol having at least one acidic group,C) from 0 to 1 mol of a polyol having 3 to 18 carbon atoms and at least 3 OH groups,D) from 1.25 to 13 mol of a diisocyanate of 6 to 30 carbon atoms andE) from 0 to 1 mol of a primary or secondary amino alcohol of 2 to 16 carbon atoms,the molar ratio of the OH and any NH groups present in the sum of the components A, B, C and E to the NCO groups of component D being from 0.98 to 1.4, is obtainable by reacting the above components in the melt and is suitable in particular as a binder for magnetic recording media.

Abstract: A polymeric material I is obtainable by reacting1) a polymer II ofa) 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 one or more further monomers andc) an 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 nonaromatic isocyanate III to give a reaction product IV, the amount of isocyanate groups being from 1.2 to 3.

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 wet-on-wet application process by means of an extrusion coater having at least two slot dies is described, the upper lip of the common outlet orifice of the slot dies being recessed relative to the lower lip and a right parallelepiped magnet whose upper edge is opposite the extruder orifice at a distance of, preferably, from 1 to 1.5 mm away being arranged on the other side of the nonmagnetic substrate and parallel to the latter, in which the uppermost layer contains magnetic pigments and has a layer thickness of more than 2.0 .mu.m while the lower layer is nonmagnetic, may contain a conductivity-increasing additive or nonmagnetic fillers and has a thickness of less than 0.5 .mu.m when dry. The magnetic recording medium has very good mechanical and electroacoustic properties, improved conductivity, very good adhesion, improved surface quality and a smaller number of dropouts.