The invention relates to a preparation method of a defoaming agent for a waterborne
system. The preparation method of the defoaming agent for the waterborne
system comprises the following steps: a) adding
silicon oil, gaseous
silicon dioxide and catalyst into a reaction container according to proportions, and preparing
silicon cream under an agitating condition protected by
nitrogen; b) adding
hydrogen-containing silicon oil and allyl polyether into the reaction container, agitating under the protection of
nitrogen, increasing temperature and adding an initiator for reaction to obtain polyether modified organic silicon; c) jading the silicon cream obtained in step a), the polyether modified organic silicon obtained in step b) and an emulsifier into the reaction container, adding water for emulsification under a high-speed agitating condition, and adding a
thickening agent to regulate
viscosity to obtain a product. The defoaming agent prepared by adopting the preparation method provided by the invention has the advantages that the
active components are low, the manufacturing cost is low and the environmental friendliness is better; the emulsification is stable, the compatibility in the waterborne
system is good, the defoaming agent is easy to disperse, the
surface tension is low, the defoaming speed is quick, the foam inhibiting time is long, the
thermal resistance,
shear resistance and acid and alkali resistance thereof are good, and the defoaming agent can adapt to various places; the defoaming agent can be separately used and can also be jointly used with other adjuvants, the stability is good, the phenomenon of oil floating due to demulsification does not occur, no
sediment is produced and shrinkage cavities during
coating are not caused; and the defoaming agent is also very effective to non-waterborne systems.