The effect of defoamers in water-based wood coatings is mainly manifested in two aspects: 1. It can keep the coating fresh, tender, and moldy; 2: It is guaranteed that no cattle foam will be produced during construction.
Improper use of defoamers in coating can cause peeling effects, not only leading to shrinkage, but also causing a decrease in the brilliance of the paint film, as well as a decrease in adhesion and water resistance. So it is necessary to pay attention to comprehensive and strict auditing, and to the selection of defoamer varieties and the manipulation of their reduction amounts. The following methods can be used to choose defoamers: crystal defoamers.
Implementation premise: 88% water-based resin strong alkali defoamer, 5% ethylene glycol butyl ether, 0.2% wetting agent‰;， Reduce the appropriate amount of defoamer and disperse at high speed under the conditions of 2000r/min and 60min;
Evaluation method: according to the amount of foam in the paint sample in the container, evaluate the foam inhibiting ability of the defoamer, and use 7Μ m wet film preparer is used to prepare films on glass, evaluating the compatibility of defoamers, the brilliance of paint films, and their drawbacks; Apply an evaluation of the defoaming ability of the defoamer on the wooden board. Therefore, for the water-based wood coatings of polychlorinated lotion fragmentary soybean milk defoamer, silicone resin defoamer can achieve better defoaming results of fermentation defoamer. The optimal attendance rate is 0.2%.
In addition, defoamers often do not separate into layers. Even if they do not separate into layers, they should be stirred evenly before use. If necessary, they should be diluted with water or cosolvents (due to the poor storage toughness of diluted defoamers, it is recommended to dilute them immediately). When arriving, it is necessary to arrive quickly under stirring, and if necessary, reduce the steps, which will result in unsatisfactory outcomes. For example, defoamers with strong field strength during grinding, and defoamers with weaker defoaming ability that may be reduced during paint mixing, can effectively alert and defend against the drawbacks of shrinkage, pinholes, fish eyes, and other defects in water-based wood coatings during construction. The shear force during stirring is used to ensure good dispersion of the particles of the defoamer, but excessive shear force weakens the defoaming effect by making the defoamer particles too small.
