Compositions – Preservative agents – Anti-corrosion
Patent
1993-02-24
1995-12-12
Lovering, Richard D.
Compositions
Preservative agents
Anti-corrosion
252358, 44320, B01D 1904, C08G 7738, C08G 7746
Patent
active
054747090
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for defoaming and/or degassing organic systems, the term organic systems also being intended to comprise those systems which are not entirely but only predominantly composed of organic compounds.
The use of a polydiene modified with organopolysiloxane groups as defoaming and/or aerating agent for organic systems is described in U.S. Pat. No. 4,906,403, in which polydiene the organopolysiloxane groups have organic radicals bonded via oxygen to silicon. The susceptibility to hydrolysis caused by this is found to be disadvantageous, especially in the case of organic systems which have a certain water content, such as, for example, crude petroleum.
A process for controlling foaming in liquid hydrocarbon fuels by adding a polysiloxane/polyoxyalkylene copolymer to the hydrocarbon fuel is described in GB-A 2 173 510, only those polysiloxane/polyoxyalkylene copolymers in which the proportion of oxyalkylene groups makes up 25 to 65 percent by weight of the calculated molecular weight of the copolymer being effective.
DD-A 255 737 (published on Apr. 13, 1988, G. Sonnek et al., Academy of Sciences of the German Democratic Republic) discloses siloxanylalkenediyl-bis-.omega.-hydroxypolyoxyalkylenes of the general formula ##STR1## in which Z denotes an organosilyl, organosiloxanyl or polyorganosiloxanyl radical, group and
When liquid hydrocarbons, such as liquid hydrocarbon fuels, are transferred from one container into another container by pumping, in the presence of air and optionally of water, for example when rapidly feeding diesel fuel from a tanker into a storage tank at a garage, a foam, which in some cases is strong and stable, forms on the surface of the liquid hydrocarbon fuel, which foam prevents rapid feeding of the liquid hydrocarbon fuel into the container and also makes it more difficult to determine the true height of the liquid surface.
Foaming also occurs when working up crude oil by distillation or in cracking processes in the refinery. In addition, foaming also occurs if crude petroleum or crude oil is delivered from a deposit under high deposit pressure and low-boiling hydrocarbons escape from the crude oil on letting down the pressure after delivery.
In addition, the lamellar foaming and the formation of small, spherical, widely separated gas bubbles (so-called microfoams) occur in the case of lubricants and hydraulic oils and also in paints and varnishes.
The aim was, therefore, to provide organopolysiloxanes which can be used for defoaming and/or degassing organic systems.
The invention relates to a process for defoaming and/or degassing organic systems by adding an organopolysiloxane-containing antifoam to the organic system, wherein the organopolysiloxane used is an organopolysiloxane composed of siloxane units of the general formula ##EQU1## in which R denotes a monovalent hydrocarbon radical having 1 to 18 carbon atoms per radical, A denotes a radical of the general formula ##STR2## in which R.sup.1 denotes a radical of the formula --CR.sup.3 H--, where R.sup.3 is a hydrogen atom or a monovalent organic radical, --CH.sub.2 CH.sub.2 CH.sub.2 --, where R.sup.4 is a hydrogen atom or a monovalent organic radical, and
Organopolysiloxanes preferably used in the process according to the invention are those in which the R.sup.2 O groups make up 0 or less than 30 percent by weight, in particular 0 to 25 percent by weight of the calculated molecular weight of the organopolysiloxane.
Organopolysiloxanes preferably used in the process according to the invention are those in which the sum of v+w is 0 to 8, particularly preferentially 0 to 4.
Preferably, the organopolysiloxanes according to the invention have a viscosity of 50 to 500,000 mm.sup.2 /s, particularly preferentially of 200 to 150,000 mm.sup.2 /s and in particular of 300 to 20,000 mm.sup.2 /s, in each case based on a temperature of 25.degree. C.
Organopolysiloxanes preferably used in the process according to the invention are those of the general formula the ratio of m:n is preferably in the range from 1:1 to 2
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Blochl Martina
Burger Willibald
Herzig Christian
Huber Peter
Innertsberger Ernst
Connaughton Martin
Lovering Richard D.
Metzmaier Daniel S.
Wacker-Chemie GmbH
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