Bayer Aktiengesellschaft

Heinrich-Christian Schopper

Rolf Wehrmann

Gunter Buxbaum

Dittmar K Nerger

Franz Hund

Rolf Naumann

Lutz Leitner

Volker Hahnkamm

Gerhard Schroeder

Coated substrates having an ultrathin, single-layer or multilayer coating of organic polymer material have been found, in which coated substrates the polymer used is a polyester of the structure ##STR1## wherein A is the skeleton of an aliphatic, araliphatic or aromatic diol,

Coated substrates having an ultrathin, single-layer or multilayer

Coated supports with ultra-thin, single-layer or multi-layer coating of organic polymer material have been found, in which, as polymer, polyurethanes of the structure ##STR1## are used in which A is the skeleton of an aliphatic, araliphatic or aromatic diol,

Coated supports with ultra-thin, single-layer or multi-layer coating,

A cobalt-doped, acicular ferrimagnetic iron oxide having an FeO content of about 16 to 24%, by weight, and a cobalt content of about 0.7 to 2.4%, by weight, the coercive force amounting to at least about 425 Oe+175 Oe/%, by weight, of Co is produced by precipitating and oxidizing a cobalt-containing aqueous iron (ii) salt solution, reducing the precipitate to Fe.sub.3 O.sub.4, partially reoxidizing to adjust the FeO content and heat treating under inert conditions at a temperature from about 600.degree. to 800.degree. C.

Production of cobalt-doped ferrimagnetic iron oxides

A metal powder, suitable for magnetic recording, consisting essentially of iron, the individual particles being acicular and containing on average no more then 5 pores and consisting on average of no more than 2 metal cores is produced by precipitating and oxidizing an aqueous iron-(II)-salt solution to produce finely divided acicular iron-(III)-oxide-hydroxide, stabilizing it as by treatment with cadmium, lead, calcium, magnesium, zinc, aluminum, chromium, tungsten, a phosphorus oxide and/or a boron oxide, converting it into ferromagnetic iron oxide of low pore content, and reducing it to metallic iron with a gaseous reducing agent at about 300.degree. to 600.degree. C.

Ferromagnetic metal pigment essentially consisting of iron and a process

In order to record and play back video signals on magnetic tape, the magnetic tape is fed past a magnetic head and reversed periodically. A stationary multi-track magnetic head is used, and a magnetic tape moves relatively thereto. The head gaps of the multi-track head are successively allocated to the lines of a half-picture in accordance with circuit technology during forward travel. In this case, the half-picture is recorded by gap-wise scanning in the form of very narrow short non-overlapping stepwise parallel tracks and is reproduced during playback. During backwards travel of the magnetic tape, the head gaps are then allocated to the lines of the half-picture in the reverse sequence so that the track sequence is shifted by at least one gap during each reversal. The gaps missing at the end of the track sequence are made up cyclically by the corresponding number of gaps at the other end of the row of head gaps.

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Krefeld, Germany

Heinrich-Christian Schopper