Peroxid-chemie Gmbh

Josef Weinmaier

Erwin Rossberger

Nikolaus Ailler

Maximilian Dorn

Eberhard Hagel

Process for a worm extruder or continuous kneader to produce either a degasses paste or plastic composition is disclosed. A mixture of either solid or liquid organic peroxides in the paste or plastic composition having evaporable constituents are introduced into the device, homogenized and degassed by exposing the mixture to a degassing passage of the extruder. The mixture has a free surface which is more than 40% of the cross-section of the degassing passage and the minimum gas passage cross-section of the return delivery device amounts to at least about 0.1 times the degassing passage cross-section.

Degassing process for a worm extruder

The present invention provides a process for cross-linking organopolysiloxanes by means of a bis-benzoyl peroxide derivative with heating, wherein, as bis-benzoyl peroxide derivative, there is used at least one compound of the general formula: ##STR1## in which the symbols R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, each independently of one another, have the following meanings: R.sup.1 and R.sup.5 are the same or different and signify alkoxycarbonyl radicals with 2 to 4 carbon atoms in the alkyl moiety or fluorine or hydrogen atoms, R.sup.2 and R.sup.4 are the same or different and signify alkyl radicals with 2 to 8 carbon atoms or hydrogen atoms and R.sup.3 signifies an alkyl radical with 1 to 8 carbon atoms or a hydrogen atom, at least 2 symbols and at most 4 symbols per benzene ring signifying hydrogen atoms. The present invention also provides an agent for carrying out this process which consists essentially of silicone oil in which is contained, in finely divided form, 10 to 80% by weight of at least one compound of general formula (I).

Process and agent for cross-linking organopolysiloxanes

A degassing device on a worm extruder having a worm housing accomodating the worm or worms and provided with at least one degassing passage opening into the worm chamber of the housing is provided with a return delivery device for material which has penetrated from the worm chamber into the degassing passage. The free surface (evaporation area) of the extruder material within the degassing passage amounts to more than about 40% of the degassing passage cross-section, and the smallest gas passage cross-section of the return delivery device amounts to at least about 0.1 times, the degassing passage cross-section. Especially in the case of pasty material this reliably prevents a blockage of the degassing passage by the material processed in the worm extruder.

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Pullach, Germany

Josef Weinmaier