Two stage mixing of rubber cpds.

摘要

Prodn. of a rubber cpd. involves addn. of non-reactive ingredients to the rubber in a first stage and addition of reactive ingredients in a second stage. After the initial mixing in the first internal mixer (1) the cpd. is fed to a second internal mixer (2) and the temp. is reduced by adding additional rubber, the temp. of this latter cpd. being lower than the temp. of the initially mixed cpd.. Also claimed is the process plant used which includes two internal mixers (1, 2), one above the other, where the mixing vol. (9) of the second mixer (2) is 70-250% larger than that of first mixer (1).