Introduction to the dosage and steps of adding defoamers to coatings

The dosage and efficacy of defoamers depend on the formulation system of the coating or ink defoamer, especially the type of polymer, pH value, pigment dosage, and the chemical structure of other additives used. Similarly, there are requirements for the type and dosage of defoamers in the manufacturing process and construction process.

When adding the amount of defoamer, it is necessary to distinguish between defoamer lotion and defoamer concentrate. The defoamer lotion droplets of lotion products have been dispersed into an ideal particle size distribution when the products are supplied. It can be added in grinding materials or during the paint mixing process, and is easily mixed evenly in coatings or inks. For defoamers that do not contain hydrophobic solid particles, they can even be added by stirring during paint formation. 

The addition method of defoamer concentrate containing 100% active substance directly affects the effectiveness of the defoamer. The particle size distribution obtained during the addition stage determines its defoaming effect. Therefore, water-based ink defoamer concentrate is usually added to the grinding base material. Defoamers are added to the system with high shear forces, but excessive shear forces can weaken the defoaming effect. The excessive dispersion and poor dispersion of defoamers are not conducive to the effectiveness of defoamers. When adding defoamers with relatively low shear forces, the initial defoaming effect may be good, but after storage, the effectiveness of defoamers may decrease. 

Generally, defoamers are designed to be used in their original state at the time of supply. If the shear force is insufficient when added, alcohol or a coagulant can be used to pre dilute the defoamer with 100% active substance. The range of dilution ratio is from 1:1 to 1:9 for defoamers, in order to facilitate the addition and improve the reasonable distribution of defoamer particle size. This is beneficial for improving the defoaming effect and reducing the tendency of shrinkage. The pre dilution of ink defoamers usually reduces the long-term stability of the defoamer active substance, so attention should be paid to the storage stability of the defoamer after dilution.