Source: {"pile_set_name": "USPTO Backgrounds"}

The problem of regulating the suds, or foaming, in aqueous systems which tend to foam excessively when they are moved or heated, has already led to numerous suggested solutions. The control of foaming over the entire washing range of a detergent or cleanser is necessary, particularly in aqueous washing and cleaning liquors, as they are used in the modern washing treatment in washing machines, particularly drum-type washing machines, because both excessive foaming and the complete absence of suds can lead to undesired results. An excellent anti-foaming agent was found in soaps based substantially upon C.sub.20 and C.sub.22 fatty acids, as they are available from rape oil and fish oils as natural sources. However, for various reasons a reliable supply of these raw materials can not be ensured. Also, the required relatively high concentration in which these fatty acids must be used, which is on the order of from 2 to 3.5 percent by weight, based on the total weight of the finished detergent, is a disadvantage.
Known silicone foam inhibitors which consists of liquid polysiloxanes with alkyl or aryl substituents and finely-divided collodial silica, effect desired suds control with very small amounts of the inhibitor, substantially below 1 percent by weight, and are in this respect superior to foam-inhibiting soaps. However, the high costs of the silicone foam inhibitors and also the great number of parameters which must be observed in suds control, have led to further efforts in this field to make new silicone-free foam inhibitors available. Liquid and solid hydrocarbons or chlorinated hydrocarbons, wax-like fatty acid esters, long-chain fatty alcohols containing up to 50 carbon atoms, fatty ketones, aliphatic disulfides or sulfoxides, and the like, partly also in combination with hydrophobic, finely-divided silicon dioxide, have been suggested as foam-inhibiting active substances. For example, a special ternary foam inhibitor consisting of a liquid hydrocarbon, a solid hydrocarbon, or a fatty acid ester, as well as a hydrophobic silicon dioxide, has become known recently from the European Patent Application No. 0 000 216.