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: Tape-like magnetic recording media having a nonmagnetic substrate and at least one layer applied to the substrate having incorporated into at least one of these layers, an inorganic needle-shaped pigment which serves as a supporting pigment and has a ratio of the average length to the average diameter of the pigment of at least 3, and the mean modulus of elasticity of the layers is not less than 15 Gpa in the longitudinal direction of the tape-like recording media.

Abstract: Described are tape-type magnetic recording media (I) including a non-magnetic substrate (III), at least one film applied to the substrate and, in at least one of these films, an inorganic acicular pigment (II) suitable for use as a supporting pigment, the ratio of the mean length to the mean diameter of the pigment (II) being at least 3 and the mean modulus of elasticity of the films being not less than 15 GPa in the longitudinal direction of the tape-type recording medium (I).

Abstract: Hydroxyl-containing polyurethanes I are composed essentially ofa) a diisocyanate of 6 to 30 carbon atoms (component II),b) a component III comprising.alpha.) an aliphatic diol of 2 to 20 carbon atoms or.beta.) an aromatic-aliphatic or aromatic-cycloaliphatic diol of 8 to 30 carbon atoms having nonphenolic hydroxyl groups as hydroxyl groups of the diol andc) a polyhydric alcohol having at least 3 hydroxyl groups, 3 to 18 carbon atoms and nonphenolic hydroxyl groups as hydroxyl groups of the alcohol (component IV),the amounts of components II to IV being such that the total number of nonphenolic hydroxyl groups is from 1.1 to 5.0 per isocyanate group of II.The polyurethanes can be used as binders or binder components for pigment-containing coatings, in particular for the production of magnetic recording materials.

Abstract: Magnetic recording media contain a nonmagnetic substrate and a magnetizable layer, the magnetizable layer containing ferromagnetic pigments and a system of polymeric materials, wherein the system of polymeric materials containsa) from 3 to 35% by weight of a polymer containing ionic or ionogenic groupsb) from 5 to 97% by weight of a polymer XIV which contains basic groups, and has a molecular weight of from 30000 to 2000000.

Abstract: Preparation of materials (I) having an average molecular weight from 4000 to 30,000, obtainable by reacting1) a polyurethane (II) comprisinga) 1 mol of a diol (III) having an average molecular weight of from 400 to 4000,b) from 0.3 to 9 mol of an aliphatic or cycloaliphatic diol (IV) of 2 to 18 carbon atoms,c) from 0.3 to 9 mol of an aromatic diol (V) of 8 to 30 carbon atoms,d) from 0.01 to 1 mol of a trihydric alcohol (VI) of 3 to 18 carbon atoms,e) from 0.001 to 1 mol of a polyhydric alcohol (VII) of 3 to 14 carbon atoms which contains a tertiary amino group andf) an amount of a diisocyanate (VIII) of 6 to 30 carbon atoms such that the molar ratio of the isocyanate groups to the total number of hydroxyl groups in (III) to (VII) is from 1.05:1 to 1.

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: 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: 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: 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: 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: Magnetic recording media are obtained by preparing a dispersion of anisotropic magnetic material and conventional 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, the magnetic layer containing finely divided organic, hydrophobic supporting pigments and a highly viscous polysiloxane.

Abstract: Magnetic recording media consisting of a nonmagnetic substrate and at least one magnetizable layer which is firmly applied thereon and is based on a magnetic material which essentially consists of ferromagnetic chromium dioxide and is finely dispersed in a polymer binder and further conventional additives are distinguished by a particular stability to the chemical decomposition due to moisture and oxidizable compounds and hence particular stability to the deterioration in the magnetic properties, as a result of the addition of from 0.1 to 8% by weight, based on the amount of chromium dioxide, of a monomeric, polyunsaturated, organic compound to the magnetic layer.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and at least one magnetizable layer which is firmly applied thereon and is based on a polyurethane binder, not less than 50% by weight of the binder consisting of a high molecular weight branched polyurethane elastomer having OH-containing urea groups at the chain ends, and the frictional properties of the binder being improved and its coefficient of friction reduced by incorporation of perfluoro groups.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and at least one magnetizable layer which is applied firmly thereon and is based on a polyurethane binder, not less than 50% by weight of binder consisting of a branched polyurethane elastomer having urea groups at the chain ends.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and at least one magnetizable layer which is firmly applied thereon and is based on a polyurethane binder which may be crosslinked with a polyisocyanate, not less than 50% by weight of the binder consisting of a low molecular weight branched polyurethane having OH-containing urea groups at the chain ends, and the frictional properties of the binder being improved and its friction reduced by the incorporation of perfluoro groups.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and at least one magnetizable layer which is firmly applied thereon and is based on a polyurethane binder which may be crosslinked with polyisocyanate, not less than 50% by weight of the binder consisting of a low molecular weight branched polyureaurethane having OH-containing urea groups at the chain ends, and the sliding properties of the said binder being improved and its coefficient of friction reduced by incorporation of siloxane groups.

Abstract: Magnetic recording media are produced by preparing a dispersion of anisotropic magnetic materials in solution in an organic binder using dispersants and further conventional additives, applying the dispersion in the form of a layer onto a nonmagnetic substrate and solidifying the applied magnetic layer, by a process in which a cylindrical grinding chamber is used which is provided with an anchor stirrer or helical stirrer and contains grinding media whose specific gravity is lower than that of the magnetic material.

Abstract: Magnetic recording media consist of a nonmagnetic substrate and one or more magnetizable layers which are firmly applied thereon and are based on a magnetic material which is finely dispersed in a polymer binder and further conventional additives and essentially consists of ferromagnetic chromium dioxide, and the said recording media are particularly stable to the chemical decomposition due to moisture and oxidizable compounds and hence to deterioration in the magnetic properties, owing to the addition of from 0.1 to 8% by weight of an organic compound from the group consisting of the antioxidants, based on the amount of chromium dioxide, to the magnetic layer.