Compositions – Frost-preventing – ice-thawing – thermostatic – thermophoric,...
Patent
1996-02-14
1998-06-02
Green, Anthony
Compositions
Frost-preventing, ice-thawing, thermostatic, thermophoric,...
106 13, C09K 318
Patent
active
057594368
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns aircraft deicing or antiicing compositions based on glycols and water.
Aircraft deicing compositions are applied to aircraft in wintery weather before takeoff to deice them or to prevent ice forming on them for a certain period (the so-called hold-over time). This goal is frequently achieved with compositions which in addition to a glycol and water contain thickeners which increase the viscosity of the fluid and thus prevent rapid runoff of the fluid off the aircraft. The thickeners are for example cross-linked, high molecular weight polyacrylic acids. The composition of such thickener-containing deicing fluids is known for example from DE-A-3 832 310. Such fluids can give long hold-over times.
At airports there is increased interest these days in recycling deicing fluids. One approach is to separate in particular the glycol component from the used fluid by distillation and use it for dissolving further deicer components.
However, such a method is not economical for thickener-containing fluids, since the thickeners, in their effect, react extremely sensitively to small changes in the compositions of the deicing fluids and therefore necessitate very careful blending of such fluids using recovered glycol.
The ISO standard 11075 describes the technical requirements of unthickened aircraft deicing fluids having a glycol content of above 80% by weight, which in use are diluted to a water content from 25 to 50% by weight. The disadvantage of such fluids as conform for example to U.S. Airforce specification MIL A-8243 D is their short hold-over time, which in practice frequently necessitates repeated deicing of an aircraft when takeoff is delayed by a few minutes. On the other hand, working up such deicing fluids and reusing the glycol component is technically relatively straight forward.
It is an object of the present invention to provide thickener-free deicing or antiicing compositions which have long hold-over times. More particularly, the object is to find compositions which distinctly exceed the 3 minute minimum hold-over time of ISO11075.
We have found that this object is achieved by thickener-free aircraft deicing or antiicing compositions based on glycols and water consisting essentially of: an oxyalkylene glycol having 4 to 6 carbon atoms, or mixtures thereof, comprising alcohols having 10 to 20 carbon atoms alkoxylated with from 1 to 10 equivalents of ethylene oxide, propylene oxide or mixtures thereof, molecular weight of from 1,000 to 10,000,
The weight percentages are always based on the total weight of the composition, the amount of water always being used to make up to 100%.
Specifically the following components are used in the compositions of the invention: Component a) is preferably used in amounts from 85 to 90% by weight. alcohols which have been alkoxylated with from 1 to 10 equivalents of ethylene oxide, preferably with 3 to 5 molecules. However, it is also possible to use surfactants based on lauryl alcohol, myristyl alcohol, palmityl alcohol and stearyl alcohol and also tallow fat alcohols. It is also possible to use mixtures of the surfactants mentioned. The surfactants are commercially obtainable or preparable by known methods, for example by reacting the alcohols mentioned with from 1 to 10 equivalents of ethylene oxide or propylene oxide. The preferred amount of surfactant is from 0.1 to 0.5% by weight. contain up to 15% by weight, based on the polymer, of comonomers such as maleic anhydride and itaconic acid. The preferred amount of this polymer is from 0.2 to 0.5% by weight. and triethanolamide are preferably used in the compositions of the invention in amounts from 0.1 to 0.5% by weight. different from component b) in amounts from 0.05 to 1.0% by weight, particularly preferably from 0.1 to 0.4% by weight. Especially if alcohols having fewer than 6 oxyalkylene groups are used as component b), it is advantageous to include a further surfactant in the compositions.
Suitable surfactants are anionic surfactants such as alkali metal salts of alkylarylsulfonat
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Pfitzner Klaus
Schrimpf Hans
BASF - Aktiengesellschaft
Green Anthony
LandOfFree
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