Basf Aktiengesellschaft

Walter Schneider

Manfred Ohlinger

Heinz Stritzinger

Eduard Schoenafinger

Job-Werner Hartmann

Fritz Hammon

Heinrich Hartmann

Manfred Niessner

Guenter Vaeth

Bertold Bechert

Stefan Wickel

Walter Herrmann

Norbert Scholz

Thomas Meyer

Juergen Beck

Horst Grosselfinger

Philipp Pister

Franz Buettner

Olaf Unbehaun

Uwe Hampel

Horst Gassmann

Heinz Hesser

Finely divided, water-soluble polymers are prepared by polymerization of water-soluble, monoethylenically unsaturated monomers in not less than 20% strength by weight aqueous solution in the presence of a polymerization initiator in a kneader by a process in which from 0.1 to 10% by weight, based on the total monomers, of a surfactant are used in the polymerization, the polymerization initially being carried out to a conversion of the monomers of not less than 60% in the absence of the surfactant or in the presence of not more than 50% of the amount of surfactant, and the remaining amount of surfactant then being added to the reaction mixture and the polymerization completed. The addition of surfactant causes the polymer gel to disintegrate with formation of fine particles.

Preparation of finely divided, water-soluble polymers

A flexible multilayer magnetic recording medium exhibiting an improved signal-to-print-through ratio coupled with an improved maximum output level and diminished dc noise, comprising a non-magnetic base and, applied thereto, at least two superposed layers consisting of a binder with magnetizable particles uniformly dispersed therein, the upper magnetic layer containing a magnetic pigment giving a signal-to-print-through ratio of less than 55db and the lower magnetic layer(s) containing a magnetic pigment giving a signal-to-print-through ratio of 55 db or more.

Flexible multilayer magnetic recording medium

Flexible multi-layer magnetic recording media comprising a non-magnetic flexible base and, applied thereto, two superposed magnetizable layers which contain a homogeneous mixture of acicular magnetic chromium dioxide in an organic binder. According to the invention, the magnetizable layer adjacent to the base contains a chromium dioxide having a specific surface area, measured by the BET method, of from 15 to 25 m.sup.2 /g, while the outer magnetic layer contains a chromium dioxide having a specific surface area, measured by the BET method, of from 26 to 35 m.sup.2 /g. Such magnetic recording media are distinguished by uniformly high sensitivity over the entire audible frequency range even if close manufacturing tolerances are not maintained.

Flexible multi-layer magnetic recording media

Acicular gamma-iron(III) oxide is manufactured by reacting an iron(II) salt solution with an aqueous solution of an alkali metal hydroxide and oxidizing the resulting suspension of iron(II) hydroxide in three stages. In a first stage, at most from 0.1 to 4% by weight of the amount of iron(II) hydroxide originally present is oxidized in the course of from 0.1 to 4 hours, in a second stage from 10 to 25% by weight of the said original amount are oxidized in the course of from 1.5 to 6 hours and in a third stage the remaining amount is oxidized. After the oxidation, the goethite formed is reduced to magnetite and the latter is then oxidized to acicular gamma-iron(III) oxide.

Manufacture of gamma-iron(III) oxide

A track or switch tamping machine wherein the machine includes tamping and ramming units having longitudinal ducts for injecting liquid binder into the ballast. The longitudinal ducts terminate in a plate or cavity within the lower portion of the tamping and ramming units. A nozzle is also included in the unit as is means for conveying liquid binder from a storage tank carried on the machine.

Apparatus for consolidating ballast

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Ludwigshafen, Germany

Walter Schneider