Compositions – Preservative agents – Anti-corrosion
Patent
1995-10-30
1997-10-21
Lovering, Richard D.
Compositions
Preservative agents
Anti-corrosion
252358, B01D 1904
Patent
active
056792867
DESCRIPTION:
BRIEF SUMMARY
This application is filed under 35 U.S.C. 371 and based on PCT/EP94/01208, filed 19 Apr., 1994.
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to aqueous dispersions of antifoam agents of which the dispersed phase contains fatty alcohols, ketones and optionally natural and/or synthetic waxes with certain melting points. The dispersions according to the invention are preferably used in papermaking.
The foaming associated with the presence or use of surface-active substances is a serious problem in a number of industrial processes. For example, in the production of paints and lacquers, especially waterborne paints, intensive foaming occurs through the stirring in of air when the formulation constituents are mixed together, i.e. during grinding of the lacquer. This foaming makes the production of paints and lacquers more laborious because the installations 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 lacquers and paints to substrates. Small air bubbles can be formed and represent not only optical surface defects, but also weak spots in the dried film because the bubbles can easily burst under impact.
Problematical foaming can also occur in papermaking on account of the air introduced into the water circuit. For example, foam marks can be left on the paper when foam passes with floated soil onto the paper web during sheet formation. In view of the growing increase in machine speeds, there is a greater danger of air entering the fiber suspension which can disrupt drainage of the paper stock on the paper machine and, ultimately, can lead to porous structures of the paper sheets. These basically known disadvantages are aggravated by the new paper machines with their closed water circuits because foam-forming and foam-stabilizing substances accumulate in the closed systems.
As the two examples clearly show, there is a considerable demand in industry for defoamers which would be capable of reducing foam already formed and for foam inhibitors which would suppress the formation of foam. In addition, antifoam agents are also supposed to drive air bubbles dissolved in liquid systems to the surface of the system--a process which plays an important part as degassing or even as deaeration, for example in lacquers. Accordingly, in the context of the present invention, antifoam agents are agents which are supposed both to reduce foam already formed and preventively to inhibit foaming and also to drive out air bubbles. These antifoam agents are expected to be effective in small quantities both in the short term and in the long term.
2. Discussion of Related Art
DE-A-30 39 393 describes an aqueous antifoam agent composition containing water, at least one higher aliphatic alcohol, at least one solid fatty acid, at least one soap of a solid fatty acid and surfactants. Although this antifoam agent is effective in the papermaking industry, there is still a need to provide even more effective antifoam agents in view of increasing requirements through faster machine speeds. In addition, the antifoam agents should only contain components which are toxicologically safe and readily biodegradable so that any antifoam agents entering the wastewater would not cause environmental problems. In addition, there was a need to find antifoam agents which would be effective at temperatures above 35.degree. C., even in the closed systems now typical of papermaking. Since, in addition, the user requires antifoam agents which are ready for use and easy to dose, another problem addressed by the invention was to enable aqueous dispersions of the antifoam agents to be formulated.
DE-A-25 53 990 describes antifoam compositions for the paint, paper and food industries which are used in the form of aqueous dispersions and of which the dispersed wax-like phase contains ketones with melting points above 70.degree. C. Other substances with a defoaming effect, such as fatty alcohols, may also be present in the dispersions. T
REFERENCES:
patent: 4087398 (1978-05-01), Heyden et al.
patent: 4303549 (1981-12-01), Boylan
patent: 4937011 (1990-06-01), Schmid et al.
Hawley's Condensed Chemical Dictionary, Tenth Edition, (Van Nostrand Reinhold Co, Inc., NY, NY) p. 1233, 1987.
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Lovering Richard D.
Metzmaier Daniel S.
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