Basf Aktiengesellschaft

Basf Magnetics Gmbh

Emtec Magnetics Gmbh

Basf Farben + Fasern Ag

Basf Aktiengesellschaft, Patentabteilung

Werner Loch

Eberhard Schupp

Rolf Osterloh

Klaas Ahlers

August Lehner

Werner Lenz

Norbert Schneider

Michael Bobrich

Hermann Roller

Rudolf Suettinger

Helmut Jakusch

Albert Kohl

Harro Petersen

Gregor Brodt

Ria Kress

Ludwig Kreitner

Hermann Dikow

Eckehardt Wistuba

Werner Balz

Jenoe Kovacs

Thomas Schwerzel

Guenther Schulz

Uwe Keppeler

Thomas Wunsch

Ingolf Buethe

Milena Melzer

Hermann Graf

Kurt Fischer

Uwe Burkhardt

Ulrich Goeckel

Attila Vass

Hellmuth Kasch

Erich Hoffmann

Hans-Joachim Jenor

Johann Voit

Alfred Lindner

Arnold Dobbelstein

Klaus Gotz

Hans-Georg Gottmann

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.

Magnetic recording medium

Hydroxyl-containing polyurethanes I are composed essentially of

Polyurethanes

Polymeric materials (I) are obtainable by reacting

Polymeric materials suitable as dispersing resins

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 of from 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 3.0 NCO groups react per OH group and the remaining NCO groups are converted into substituted terminal urea groups with a polyfunctional amine or with a mixture of different polyfunctional amines.

Magnetic recording medium containing magnetic material dispersed in a

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.

Magnetic recording medium having a magnetic layer containing chromium

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.

Magnetic recording media having a branched thermoplastic polyurethane

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.

Magnetic recording media

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.

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.

Reaction products and condensates based on substituted propyleneureas

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

Binders for cathodic electrocoating

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

Synthetic resin containing quaternary ammonium groups, its preparation,

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.

Binders for cathodic electrocoating which contain non-tertiary basic

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 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.

Urea/polyamine/secondary monoamine/polyalcohol condensate

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

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Erpolzheim, Germany

Werner Loch