Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ
Patent
1995-11-09
1998-03-10
Cooney, Jr., John M.
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
264 42, 264 50, 264 51, 264 52, 521 99, 521114, 521117, 521149, 521155, B29C 6500
Patent
active
057258155
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the use of block copolymers containing alkylene oxide units as foam control agents in the production or further processing of foods, paints, lacquers, paper and in fermentation processes.
In the industrial production and/or processing of foods, considerable importance is attributed to the control and prevention of foam. For example, in the industrial processing of sugar-containing plant juices, as practised on a large scale in the processing of sugar beet, particular difficulties are caused by excessive foaming in recovery and purification of the juice and in the evaporators. The foam control agents used in the sugar industry must of course be physiologically safe. The same applies to foam control agents used in the manufacture of potato products, such as chips or French fries, or even in the production of baker's yeast using molasses. In addition, the foam control agents used in the potato-processing industry must be capable of regulating starch foam which is difficult to control. In addition, the user always expects foam control agents to develop good spontaneous and long-term activity in small amounts.
2. Discussion of Related Art
Fats and oils, such as rapeseed oil, peanut oil, olive oils and wool grease, have long been used for foam inhibition in the sugar and yeast industries. Synthetic esters, such as fatty acid monoglycerides, fatty acid polyglycol esters, and synthetic alcohols, such as polyalkylene glycols and alkylene oxide adducts with fatty alcohols, have also been proposed for this purpose. Although a certain foam-suppressing effect can be achieved with these compounds, they often have to be used in excessive quantities or only develop their effect at certain temperatures and not over broad temperature ranges.
In the case of lacquers and paints, air can be stirred in during homogenization of the paint or lacquer ingredients. This is a particular disadvantage because either the user has to wait a very long time for the air bubbles to burst before he can begin applying the paint or lacquer or, alternatively, the lacquer or paint coating contains bubbles. Paint or lacquer coatings with surface defects are not only optically unattractive, they are also far from durable because dried bubbles readily lead to flaking of the films. In order to avoid troublesome air bubbles both during homogenization and during application, silicone-based foam control agents are best added. Although these foam control agents are capable of effectively destroying the air bubbles, they are attended by the major disadvantage that the paint or lacquer coating on various substrates, for example glass, is uneven. This is presumably because the highly hydrophobic silicones prevent thorough and uniform wetting of the substrate to be coated.
Troublesome foam can also be formed in the paper-making industry through a high air content in the water circuit of papermaking machines. Thus, foam marks can appear on the paper when foam passes with floated soil onto the paper web during sheet formation. Since increasingly higher machine speeds are also being used in papermaking, there is an increased risk of air entering the fiber suspension. The air thus incorporated interferes with dewatering of the paper stock on the paper machine in the form of air bubbles and leaves the paper sheet with a porous structure. These disadvantages are intensified by the latest papermaking machines because the water circuits are now increasingly closed. Foam-forming and foam-stabilizing substances collect in the closed systems. In addition, the temperature of the circulated water of the papermaking machine can change during production. Accordingly, foam inhibitors which develop a long-term effect over wide temperature ranges in small quantities are also required in the papermaking industry.
International patent application WO 92/11074 describes foam inhibitors based on carboxylic acid derivatives, for example esters and amides of citric acid, tartaric acid, succinic acid, ma
REFERENCES:
patent: 4092266 (1978-05-01), Abel et al.
De Haut Christian
Eicken Ulrich
Fischer Herbert
Gress Wolfgang
Moeller Thomas
Cooney Jr. John M.
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Szoke Ernest G.
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