Compositions – Preservative agents – Anti-corrosion
Patent
1997-02-20
1998-09-15
Lovering, Richard D.
Compositions
Preservative agents
Anti-corrosion
252358, 252312, B01D 1904
Patent
active
058075020
DESCRIPTION:
BRIEF SUMMARY
This application is filed under 35 U.S.C. .sctn. 371 and is based on PCT/EP95/02260, filed Jun. 12, 1995.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to aqueous fatty alcohol dispersions and to their use as antifoam agents, preferably in the paper industry, in the wastewater sector, in the building industry and in the production of waterborne paints and also to their use as an additive for dispersion-bonded plasters.
The generation of foam associated with the presence or with the use of surface-active substances is a serious problem in a number of industrial processes. Thus, in the production of paints and lacquers for example, intensive foaming occurs during grinding of the lacquer through the stirring in of air. This foaming makes the production of paints or lacquers more laborious because the plant can only be filled and operated with a fraction of the available volume. At the same time, however, foaming can also occur when the user wants to apply paints or lacquers to substrates. Small air bubbles can form and represent not only visible surface defects, but also weak spots in the dried film because they can easily burst under impact.
Problematical foams are also formed in papermaking on account of the air introduced into the water circuit. For example, foam stains can occur on the paper when foam passes onto the paper web during the sheet forming process. The increasing speeds at which papermaking machinery is operated increase the overall danger of air being mixed into the fiber suspension which can adversely affect the drainage of the paper stock on the papermaking machine and, ultimately, can lead to porous structures of the paper sheets. These basically known disadvantages are increased by the new papermaking machines with closed water circuits because foam-forming and foam-stabilizing substances accumulate in the closed systems. As the foregoing observations suggest, there is a considerable need in the industry both for defoamers which are capable of reducing foam which has already formed and for foam inhibitors which are intended to suppress the generation of foam. In addition, antifoam agents are also intended to drive air bubbles dissolved in liquid systems to the surface of those systems--a process which plays a major role as degassing or even as deaeration, for example in paints. Accordingly, antifoam agents in the context of the invention are intended both to reduce foam which has already formed and preventively to inhibit foaming and also to drive out air bubbles. These antifoam agents are expected to develop their effect quickly and durably in small quantities.
To solve the problems caused by foam in the building industry, there is a need for defoamers which are effective, do not cause any surface defects, do not undesirably sensitize the surfaces to water and--in gypsum boards for example--do not affect adhesion.
In the case of dispersion-bonded plasters, such as synthetic-resin- and silicate-bonded plasters, a long so-called open time is required for application to enable good grindability and the required plaster structures to be obtained. The high formulation-related percentage contents of additives and application to generally absorbent substrates result in a rapid release of the water present so that the open time is seriously limited. As soon as the setting process, i.e. drying, begins, the opportunity to structure or texture the surface is lost. At relatively high ambient temperatures in particular, the rapid release of water leads to a critical reduction in the open time of the dispersion-bonded plasters. Accordingly, there is a considerable need in the industry for additives which are capable of extending the open time of dispersion-bonded plasters.
2. Discussion of Related Art
Aqueous fatty alcohol dispersions are used in both fields of application. Thus, DE-A-36 01 929, for example, describes defoamers based on oil-in-water emulsions in which the oil phase of the emulsion contains a C.sub.12-26 alcohol, a fatty acid ester and a hydrocarbon an
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Hoefer Rainer
Schulte Heinz-Guenther
Wollenweber Horst-Werner
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Lovering Richard D.
Metzmaier Daniel S.
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