Bayer Aktiengesellschaft

Heinz Fischer

Friedhelm Muller

Gunter Sackmann

Gunter Kolb

Useful boosters in admixture with a peptiser for viscosity degradation of diene rubber or its mixtures are:

Process and composition for viscosity degradation of diene rubbers

An improved process for the production of a substantially equimolecular copolymer of maleic acid anhydride and diisobutylene in which from 10 to 100 mole % of the anhydride groups are esterified with linear or branched aliphatic monoalcohols containing from 1 to 20 carbon atoms or with cycloaliphatic monoalcohols containing from 5 to 6 carbon atoms to form the corresponding semiesters, wherein shortly before or after the end of the solution or suspension copolymerization of maleic acid anhydride and diisobutylene a monomer corresponding to the general formula ##STR1## in which R=H, CH.sub.3, C.sub.2 H.sub.5, --OR.sub.2, --O--CO--CH.sub.3, ##STR2## --CH.sub.2 OH, --CH.sub.2 O--C--CH.sub.3, R.sub.1 =H , CH.sub.3 and

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Pulheim, Germany

Heinz Fischer