Hoechst Aktiengesellschaft

Werner Schafer

Joachim Berthold

Wolfgang Strobel

Rainer Franke

Bernd Diedrich

Jurgen Hartlapp

Hartmut Hensel

Hermann Dallman

A coextruded, biaxially draw-oriented, multi-layer polyester film as a base film for magnetic tape is described, whose characteristics are that the total thickness of the multi-layer film is no more than 10 .mu.m, the surface roughness of the base film on the side intended for the application of an information-carrying coating has an R.sub.a value (DIN 4768) of less than or equal to 0.010 .mu.m and the surface roughness of the opposite side of the base film which is not intended for application of an information-carrying coating, has an R.sub.a value of greater than 0.010 .mu.m and that the film has an E-modulus in the machine direction of greater than or equal to 6500 N/mm.sup.2.

Multi-layer polyester film for magnetic tape

Polyolefins having a broad molecular weight distribution are obtained in a very high yield even using a catalyst based on a reaction product of a magnesium alcoholate with titanium tetrachloride, if the hydrocarbon-insoluble product of the reaction of the magnesium alcoholate with titanium tetrachloride is heated to a fairly high temperature with a chloroalkoxytitanate, in order to split off alkyl chlorides.

Process for the preparation of a polyolefin, and a catalyst for this

Polyolefins having a broad molecular weight distribution are obtained in a very high yield even using, as the catalyst, a product from the reaction of a magnesium alcoholate with titanium tetrachloride, if the reaction between the magnesium alcoholate and the titanium tetrachloride is carried out at a relatively low temperature and the reaction mixture is then heated to a fairly high temperature in order to split off alkyl chlorides.

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Hofheim am Taunus, Germany

Werner Schafer