Wacker-chemie Gmbh

Manfred Riederer

Martin Piehler

Hartmut Menzel

A continuous method for altering the molecular weight of organosilicon compositions containing Si-bonded oxygen in the presence of a catalyst and preferably under decreased pressure, in which a cylindrical reactor is employed have a ratio of length to inside diameter of between 1:1 and 50:1. A reactive mixture is stirred in the cylindrical reactor by a stirring apparatus having one or more stirring blades, so that the mixture is subjected to a maximum centrifugal acceleration b.sub.max of at least 70 m.s.sup.-2 and more preferably at least 165 m.s.sup.-2.

Continuous method for altering the molecular weight of organosilicon

This invention relates to a method for stabilizing organopolysiloxane oils containing triorganosiloxy groups in their terminal units, in which the organopolysiloxane oils are contacted with compounds having the formulas:

Stabilized organopolysiloxane oils

Diorganopolysiloxanes may be polymerized to increase their molecular weight by heating the siloxane in the presence of a quaternary phosphonium hydroxide, in which one of the substituents on the phosphorus atom of the phosphonium cation is a monovalent radical containing carbon, hydrogen and silicon atom(s) and possibly siloxane oxygen atoms(s) and the three remaining substituents on the phosphorus atom are the same or different hydrocarbon radicals that are free of aliphatic carbon-carbon multiple bonds.

Method for increasing the molecular weight of diorganopolysiloxanes

In a process for varying the molecular weight of linear or cyclic organopolysiloxanes in the presence of a catalyst which is solid in the reaction mixture at the reaction temperature, the improvement comprising that the catalyst which is solid in the reaction mixture at least at the respective reaction temperature and the organopolysiloxane whose molecular weight is to be changed are continuously and simultaneously passed through a heated cylindrical reactor whose contents is mechanically moved, the reactor having a length to inside diameter ratio of 1:1 to 20:1 and its interior pressure being held at 50 to 500 hPa (abs.) and the catalyst is removed from the mixture after leaving the reactor.

Continuous process for varying molecular weight of organopolysiloxanes

A process for stabilizing organopolysiloxanes against changes in viscosity which comprises reacting organopolysiloxanes containing phosphonitrile chlorides or reaction products thereof with at least one lithium compound which forms lithium chloride when reacted with the chlorine bonded to the phosphorous compound.

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Burghausen, Germany

Manfred Riederer