Silicone oil emulsion defoaming agent is generally oil-in-water (O/W) emulsion, that is, water is continuous phase, silicone oil is non-continuous phase.It is to premix silicone oil, emulsifier and thickener, and then gradually add water to stir evenly, and finally grind repeatedly in colloid mill until the emulsion meets the requirements.

Silicone oil emulsion defoaming agent is the most widely used and the largest amount of silicone defoaming agent.It is easy to disperse in water system and can be widely used as defoaming agent in water phase system.Good defoaming effect can be obtained by adding the emulsion directly into the foaming system.In order to improve the defoaming effect of emulsion and the accuracy of measurement, concentrated silicone oil emulsion of more than 10% is generally not directly used: instead, it is first diluted to below 10% with cold water or directly with foaming liquid.Do not use hot or cold liquid dilution, otherwise it will cause emulsion breaking.The stability of emulsion will deteriorate after dilution, and the storage process may also occur stratification (oil bleaching) phenomenon, that is, demulsification.Therefore, the diluted emulsion should be used up as soon as possible.Thickener can be added if necessary to improve the stability of the emulsion.For the intermittent operation process, silicone oil emulsion can be added once before the system operation, or batch replenishment can be adopted.For continuous operations, silicone oil emulsions should be added continuously or intermittently at appropriate parts of the system.

The use of emulsion defoaming agent, especially to consider the foaming system temperature and acid, alkaline conditions, because silicone oil emulsion is more delicate, more than its range of use, the emulsion will be premature demulsification, become inefficient or ineffective (silicone oil emulsion dosage, generally foaming liquid weight of 10 ~ 10Oppm (silicone oil meter).Of course, there are special cases of less than 10ppm and more than 100ppm.The optimum dosage is mainly determined by experiment.

The general silicone oil emulsion defoamer is mostly oil-in-water.According to the different types of silicone oil, silicone oil emulsion defoaming agent has the following types:

1.Silicone oil emulsion with dimethyl silicone oil as the main body

This kind of defoamer is made up of dimethyl silicone oil plus emulsifier and water, which can be widely used in fermentation, food, paper making, fiber, pharmaceutical, synthetic resin and so on.

2.Silicone oil emulsion with methyl ethoxy silicone oil as the main body

This kind of defoaming agent is made of methyl ethoxy silicone oil and compound.