The same pigment has different hues in different resin systems. Almost all carbon blacks, organic pigments and transparent iron oxides change their own hue, especially the scattering hue, with different resin systems. Therefore, choosing a suitable dispersant is not only used to disperse and stabilize the pigment, but also to adjust the pigment to finally achieve the correct color we need, such as blackness, transparency, and shade at 45°. Therefore, the coordination of dispersant and resin includes:
－Compatibility (sampling test, check compatibility after removing solvent)
－The viscosity reduction behavior of the dispersant in the resin system to determine the pigment (rotation viscometer test)
－Dispersant in the resin system to determine the color development behavior of the pigment (scrape colorimetric)
– Storage stability (flow plate method).
Although the foam theory is very instructive for us to solve the trouble caused by the foam problem, people’s understanding of the foam problem has not yet matured. So far, there is no “standard defoamer mechanism” that is generally accepted by the industry. The foam problem of solvent-based coatings and water-based coatings in coatings is obviously different, and the solution methods are also different, e914 oxidised polyethylene wax indicating that this subject area still needs to be discussed in depth.
Classification and variety introduction of defoamers
1. Classification of defoamers
For the varieties of defoamers used in various coatings. They have obvious effects, strong specificity, and will not have any unacceptable side effects. Therefore, they are more complicated than non-coating defoamers. They are usually supplied in liquid form, but sometimes in powder or water emulsion form. Liquid type defoamers are mostly compound types, especially those used in latex paint. In order to facilitate the use of pumps to transport materials in automated production, this type of defoamer has a low viscosity. According to current habits, defoamers for coatings can be divided into three major categories 11.3.20]: ①Mineral oil defoamers; ②Polydimethylsiloxane or modified polydimethylsiloxane, commonly known as Silicone defoamer; ③ Silicone-free polymer defoamer.
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