Abstract: A magnetic recording medium consisting of a nonmagnetic substrate and at least two magnetizable layers which are applied thereon and contain metal oxides as magnetic pigment is described, the pigment of the upper layer having a higher BET value than that in the lower layer. According to the invention, the upper layer has a thickness in the range of 3-5 .mu.m when dry and the lower layer a thickness in the range of 1.1-3 .mu.m when dry. Particularly advantageous results are obtained when the magnetic pigment of the upper layer is cobalt-doped .gamma.--Fe.sub.2 O.sub.3 and that of the lower layer is acicular CrO.sub.2. With the double-layer recording medium obtained according to the invention, in particular the output level at low frequencies is improved without the frequency curve showing the usual depression in the middle.

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: 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 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 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 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.

Abstract: In magnetic recording media which have at least one magnetizable layer firmly applied to a nonmagnetic base, the magnetizable layer essentially consists of a magnetic material finely dispersed in an organic polymer binder, a dispersant, a lubricant and other conventional additives.

Abstract: Condensates based on substituted ureas, their reaction products with di- and/or polyisocyanates, derivatives of di- and/or polycarboxylic acids or p-substituted phenols and/or their methylol derivatives, their preparation and their use. These condensates each contain two or more cyclic urea units and can be prepared either by reacting primary di- or polyamines with ureas and reacting the product with predominantly CH-acidic aldehydes or by reacting primary amines with isocyanates and reacting the product with predominantly CH-acidic aldehydes in the presence of an acidic catalyst. The said condensates and their reaction products are useful for the preparation of heat-curable coating materials and of binders for cathodic electrocoating.

Abstract: Binders for cathodic electrocoating which are based on polyadducts/polycondensates which carry basic nitrogen groups and are rendered water-dilutable by protonation with an acid, and one or more crosslinkng agents for these polyadducts/polycondensates, and their use.These binders essentially consist of a mixture of(A) from 50 to 90% by weight of a polyadduct/polycondensate which carries basic nitrogen groups and is obtainable by reacting(a) an adduct of a secondary amine and a polyepoxide compound, the adduct still containing free epoxide groups, with(b) a condensate which contains primary amino groups and is obtained from a primary diamine of not less than 4 carbon atoms and one or more mono- and/or dicarboxylic acids, one or more primary amino groups of the condensate (b) being used per free epoxide group of the adduct (a), and(B) from 10 to 50% by weight of a crosslinking agent which does not react with component (A) at room temperature but reacts with the latter at elevated temperatures with crosslinking.

Abstract: A synthetic resin which contains quaternary ammonium groups, and its preparation.The water-dilutable synthetic resin which contains quaternary ammonium groups and furthermore contains one or more basic secondary and/or tertiary amino groups per quaternary ammonium group is an adduct of(A) a quaternary ammonium salt which is obtained by reacting(a) an organic compound containing two or more basic amino groups per molecule, one of which is a primary group and is protected as a ketimine by prior reaction with a ketone, and the remaining groups are tertiary groups, with(b) an organic or inorganic acid and(c) a monoepoxide compound, and, if necessary, then eliminating the ketone hydrolytically,(B) a resin which contains on average from 1.5 to 3.0 epoxide groups per molecule, and, if required,(C) one or more monofunctional organic compounds whose functional group is capable of undergoing an addition reaction with an epoxide.

Abstract: The present invention relates to binders for cathodic electrocoating. These binders contain non-tertiary basic amino groups in addition to phenolic Mannich bases and consist of a mixture or precondensate of a polymer, polycondensate or polyadduct which has a mean molecular weight of 800 to 8,000 and a content of basic, primary and/or secondary amino groups of 0.8 to 8 equivalents per 1,000 molecular weight units and one or more phenolic Mannich bases prepared from one or more polynuclear polyphenols, formaldehyde or a formaldehyde donor and one or more secondary aliphatic amines, not more than one equivalent of a secondary amine and not more than 2 equivalents of formaldehyde being employed per equivalent of phenol for the preparation of component (B). These binders can be rendered water-dilutable by the addition of an acid and are suitable for the cathodic electrocoating of electrically conductive articles.

Abstract: Binders for cathodic electrocoating which are based on polyadducts/polycondensates which carry basic nitrogen groups and are rendered water-dilutable by protonation with an acid, and one or more crosslinking agents for these polyadducts/polycondensates, their use and electrocoating baths prepared from them.These binders essentially consist of a mixture of(A) from 50 to 90% by weight of a polyadduct/polycondensate which carries basic nitrogen groups and is obtainable by reacting(a) an essentially epoxide-free adduct of a secondary amine and polyepoxide compound with(b) a condensate of a diamine/polyepoxide adduct which is prepared in the presence of excess diamine and separated off from excess diamine after complete conversion of the epoxide groups, with one or more mono- and/or dicarboxylic acids of not less than 6 carbon atoms.(B) from 10 to 50% by weight of a crosslinking agent which does not react with component (A) at room temperature but reacts with the latter at elevated temperatures with crosslinking.

Abstract: A processor for the preparation of urea condensates and the preparation of heat-curable surface coatings.To prepare these urea condensates, primary di- and/or polyamine is reacted with urea, a secondary monoamine and a polyalcohol which contains certain groups at elevated temperatures and in the presence or absence of a catalyst, and the ammonia formed is separated off.These urea condensates are suitable as binder components in heat-curable surface coatings, in particular for heat-curable cathodic electrocoating finishes.

Abstract: A synthetic resin carrying basic nitrogen groups, its preparation, coating materials prepared from this resin, and a process for cathodic electrocoating.This synthetic resin is obtained by reacting(A) an epoxy resin which(B) a diketimine of a diprimary amineand, if required,(C) with a secondary amine, which may additionally contain a tertiary amino group, with a ketimine of a primary monoamine and/or with a ketimine of a primary/tertiary diamine,a diketimine obtained from(B.sub.1) a ketone and(B.sub.2) a branched aliphatic diprimary diamine of 5 to 9 carbon atoms and/or(B.sub.3) one or more diaminodiamides which are obtained by condensation of 2 moles of diamine (B.sub.2) and 1 mole of a dicarboxylic acidbeing employed as component (B).After protonation with an acid, this synthetic resin is useful as a binder for cathodic electrocoating.

Abstract: A process for the preparation of stable aqueous aldehyde resin dispersions and for the production of surface coating binders.For this purpose, a melt or highly concentrated solution of a polycondensate of urea and a CH-acidic aldehyde, with or without formaldehyde, is dispersed in water in the presence of an organic protective colloid and, if required, an emulsifier.These aqueous resin dispersions can be used, in combination with other film formers, as surface coating binders.

Abstract: Heat-curable surface-coating agents useful not only for application as solvent-containing finishes and for powder coating but also, in their protonated form, for cathodic electrocoating contain, as a binder, a mixture of (A) a polyadduct, polycondensate or other polymer having an average molecular weight M.sub.n of from 500 to 10,000 and, per molecule, on average two or more OH and/or primary and/or secondary amino groups and (B) a reaction product of (a) one or more polyisocyanates, (b) one or more secondary monoamines and, if appropriate, (c) one or more polyalcohols having two or more hydroxyl groups.

Abstract: Synthetic resins which are self-crosslinking under the action of heat have on average two phenolic hydroxyl groups per molecule and are prepared by reacting a reaction product of an epoxy resin and a bifunctional phenol with formaldehyde and a mixture of secondary amines.After they have been protonated with an acid, the resins are suitable as cathodic electrocoating binders.

Abstract: Binders useful for cathodic electrocoating are water-dilutable on addition of acid and comprise a mixture of(A) a polyadduct which carries basic nitrogen groups and contains groups of the formula (I) and/or (II) ##STR1## where R.sup.1 and R.sup.2 are hydrogen or methyl and R.sup.3 and R.sup.4 are alkyl or hydroxyalkyl or together are a 5- or 6-membered ring, and(B) a reaction product of a polyisocyanate and an olefinically unsaturated amine which carries a secondary amino group and a methacrylamide or methacrylate group.

Abstract: Heat-curable surface-coating agents useful not only for application as solvent-containing finishes and for powder coating but also, in their protonated form, for cathodic electrocoating contain, as a binder, a mixture of (A) a polyadduct, polycondensate or other polymer having an average molecular weight M.sub.n of from 500 to 10,000 and, per molecule, on average two or more OH and/or primary and/or secondary amino groups and (B) a reaction product of (a) one or more polyisocyanates, (b) one or more secondary monoamines and, if appropriate, (c) one or more polyalcohols having two or more hydroxyl groups.