Classification of traditional water-based coating defoamers

2021-09-24   Pageview:287

There are three major categories: mineral oil defoamer, polysiloxane defoamer and other types of defoamer.

Mineral oil defoamers are more commonly used, mainly in flat and semi-gloss emulsion paints.

Polysiloxane defoamer has low surface tension, strong defoaming and foam inhibition ability, does not affect the gloss, but when used improperly, it will cause defects such as film shrinkage and poor recoatability.

Traditional water-based coatings defoamer to incompatible with the water phase to achieve the purpose of defoaming, so easy to produce surface defects of the coating.

 

 

 

 

 

 

 

 

 

 

 

There are many non-polar resins used in coatings. Because of the lack of active groups, it is difficult to produce chemical adsorption. Even if it is adsorbed on the surface of the pigment, it is difficult to stabilize due to weak adsorption or thin adsorption layer. Just like perchlorovinyl paint, there is no wetting and dispersing agent, and there are often undesirable phenomena such as precipitation and floating color.

In this non-polar resin base material, for the dispersion of inorganic pigments, a low-molecular control flocculation type wetting and dispersing agent can be used. When applying, pay attention to the resin concentration when grinding the color paste, and consider making the dispersant more It absorbs to the surface of the pigment more frequently, and makes up for the defects of resin adsorption through the bridge connection of the dispersant, and plays the role of preventing sinking and floating color. When choosing a dispersant, pay attention to byk wax additives the characteristics of the pigment surface and the compatibility with the resin. Disperse inorganic pigments in this non-polar resin and choose a polymer dispersant to get better results.

Application of polymer wetting and dispersing agent
Polymer dispersants are mostly used in organic pigments. Because the surface of organic pigments lacks surface activity like inorganic pigments, it is difficult for traditional surfactants to be adsorbed on the surface. Even if adsorption can occur, most of them are physically adsorbed and have fewer adsorption points. , Poor fastness, low molecular weight, can not produce good steric hindrance, easy to flocculate, and poor stability.

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