The lotion type silicone defoamer is usually an oil in water lotion, which is easy to disperse in water systems, so it is widely used for defoaming in aqueous systems. Silicone oil is difficult to emulsify. Although ionic emulsifiers have good emulsifying effects, non-ionic emulsifiers are more preferred in industry due to their tendency to foam.
The research shows that the smaller the particles of the organosilicon lotion are, the stronger the defoaming ability is, but the required emulsion dosage also increases, which may lead to the increase of the viscosity of the lotion, thus reducing the defoaming performance. Therefore, the suitable particle size of lotion is 1-10 μ M.
Silicone oil lotion defoamer is the most widely used defoamer with the largest amount. When used, the lotion can be directly added to the aqueous foaming system. In order to improve defoaming effect and metering accuracy, silicone oil lotion with concentration more than 10% is usually not used directly, but diluted to below 10%. When diluting, it is necessary to avoid using liquids that are too hot or too cold to prevent demulsification. The stability of diluted lotion is reduced, and stratification or demulsification may occur, so it should be used as soon as possible. If necessary, thickeners can be added to improve stability.
For intermittent operation, silicone oil lotion can be added at one time before system operation, or added in batches; Continuous operation involves continuous or intermittent addition at appropriate positions in the system. The temperature, pH and other conditions of the system should be considered when using, because the silicone oil lotion is more sensitive and may be demulsified in advance beyond the scope of use, reducing the effectiveness. The amount of lotion is generally (10~100) × 10-6 of the weight of foaming liquid. In special cases, the amount may be different, and the best amount should be determined through tests.