Composition of defoamer and defoaming principle
Originality: Old Paint Workers

(1) Composition and function of defoamer


The main components of defoamer are as follows:


The carrier and expander are mineral oil, paraffin, oxygen-containing oil, natural oil, aliphatic alcohol, etc.


(2) The absorbent of surfactant molecule is wax soap, amino compound, hydrophobic silicon dioxide, etc.


(3) mechanical damage to foam wall components. The component is also an adsorbent for extender and surfactant, which is silicone oil modified by silicone oil.


(4) The compatibility regulating component is nonionic surfactant.


Defoamers for waterborne coatings contain water-insoluble hydrophobic components, such as gas-phase silicon dioxide, metal salts of stearic acid, fatty acid derivatives and polyurea compounds, which exist in the form of particles. Hydrophobic particles are dispersed in water-soluble defoamers and thus have the characteristics of concentration on the liquid surface. This makes it possible to effectively absorb bubbles in water and bubbles on the liquid surface. In addition, the composition of defoamer has the properties of low surface tension, expanding on the surface of foaming liquid, thinning the wall of bubble film, and eliminating the interfacial activator adsorbed on the surface of bubble and maintaining the stability of bubble. These properties of defoamers enable them to effectively eliminate bubbles. In practical application, due to the addition of defoamer, when bubbles are produced in paint during production, bubbles can contact with bubbles to form larger bubbles and quickly rise to the surface to defoam; in paint painting, bubbles do not appear immediately after painting or disappear before drying.


There are many effective chemical constituents as defoamers, such as metal soap, paraffin, silicone and composite silicone. Generally speaking, these four kinds of substances do not have any defoaming effect when they are added to the coatings alone, but significant defoaming effect can be obtained through the chemical changes and compound action of these substances. For example, through the use of trace silicone and compound silicone, the original paraffin and metal soap defoamers can be transformed into defoamers, which are widely used at present.