SiOC-bonded polyether siloxanes are produced by transesterification of alkoxysiloxanes with polyetherols in the presence of trifluoromethanesulfonate as catalyst. The computational total water content of the reactants including alkoxysiloxanes and polyetherols is 5000 ppm by mass, advantageously 300 ppm by mass, preferably 150 ppm by mass, more preferably 100 ppm by mass, in particular 50 ppm by mass. The determination of the individual water contents is performed beforehand, preferably by titration according to Karl Fischer.

A reaction product containing a non-cyclic alkoxy-functional polysiloxane is produced by heating a reaction system, which contains a cyclic polyorganosiloxane of the formula [(R.sup.1.sub.2SiO).sub.2/2].sub.n, where the subscript n is an integer of at least 4 and each R.sup.1 is an alkyl group or aryl group; a silane of the formula R.sup.2.sub.(4m)Si(OR.sup.3).sub.m, where the subscript m is an integer from 1 to 4, each R.sup.2 independently is an alkyl group or aryl group, a hydrocarbyl group or a halogenated hydrocarbyl group and each R.sup.3 independently is an alkyl group; and a catalyst system comprising a metal trifluoromethanesulfonate of the formula [M].sup.+[CF.sub.3SO.sub.3].sup., where M is a metal atom selected from sodium (Na) and potassium (K), and a Brnsted acid, wherein Brnsted acids having a pKa3.0, preferably having a pKa2.0, particularly preferably having a pKa0.0 are used.

Branched SiOC-linked polyethersiloxanes have the following formula (I)

##STR00001##

where R.sup.1 is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, but preferably 90% of the radicals R.sup.1 are methyl radicals; b has a value of from 1 to 10; a has a value of from 1 to 200, preferably 10 to 100, a value of from 3 to 70 when b is 1 and 4, or a value of from 3 to 30 when b is >4; and R.sup.2 denotes identical or different polyether radicals, but at least one radical R.sup.2 is a structural element radical of formula (II):

##STR00002##

where p=at least 2, preferably p=2-6, particularly preferably p=3.

The present invention relates to a defoamer oil compound that contains an organopolysiloxane (A), a fine silica powder (B), and a group (C) that is represented by the organopolysiloxanes of formulas (I) and/or (II) ##STR00001##
(in the formulas, c, d, and e are each an integer of 0 or more, and at least one of X.sup.1 to X.sup.3 is the group represented by formula (i)). The component (C) is used as a surface treatment agent for the component (B). The present invention makes it possible to obtain a silicone-based defoamer composition that imparts good initial defoaming properties even in an alkaline foaming liquid, that exhibits very little loss in performance over time, and that has excellent defoaming performance.

Effective defoamer compositions contain two different aryl-substituted organopolysiloxanes and filler particles, and show high defoaming capability.

Effective defoamer compositions contain two different aryl-substituted organopolysiloxanes and filler particles, and show high defoaming capability.

A defoaming agent obtainable by a process, the process including the step of: (i) polymerizing (B) at least one defoaming agent monomer in (A) a polymerization solvent under coexistence of (C) a polymer soluble in the polymerization solvent.

A separation system includes an elongated separator vessel having an inlet, a heating section which is located downstream of the inlet, an oil accumulation section which is located downstream of the heating section, and an oil outlet which is connected to the oil accumulation section. The heating section includes an immersed plate heater which is fluidly connected to a heating medium heater that is located externally of the separator vessel. In operation, a heating fluid which is heated in the heating medium heater is circulated through the immersed plate heater to heat the multiphase fluid.

A lubricating oil composition including: a lubricant base oil; (A) a first defoaming agent obtainable by a process, the process including the step of: polymerizing (b) at least one defoaming agent monomer in (a) a polymerization solvent under coexistence of (c) a polymer soluble in the polymerization solvent; and (B) a second defoaming agent being a silicone defoaming agent.

The invention relates to the use of a polysiloxane having a plurality of siloxane groups and at least one tertiary amide group covalently linked as a pending and/or terminal group to the polysiloxane, as a defoaming agent in a liquid composition.