The surface of matting agent with organic treatment will improve the surface scratch resistance and abrasion resistance of the paint film.
Ionic crystalline particles Ba SO, the Ba²+ concentration in the dispersion medium is large, the particles are positively charged, and the SO concentration is large, the particles are negatively charged. The apparent charge of Ba particles becomes zero at a certain concentration, and this concentration is called the zero point of charge.
If the particles with surface dissociation groups have ionization groups on the particle surface, they will be ionized in water to generate interface charges. For example, carbon black having acidic groups such as phenolic hydroxyl groups and carboxyl groups on the surface of the particles is negatively charged in water, wax additive quality and carbon black does not change the sign of the charge due to the high or low pH value.
But a particle like protein has two groups-NH2 and -COOH, which are positively charged when the pH value is low, and negatively charged when the pH value is high, and have an isoelectric point. Another example is clay-like particles (bentonite). Because of lattice defects, they have a strong affinity with H+ and OH- in water, and these ions will be charged when they are adsorbed.
Zhao Guoxi pointed out that on the surface of pigments such as alumina, titanium dioxide, and ilmenite, the adsorption amount of ionic surfactants is related to the pH value. When the pH value is higher, the adsorption of cationic surfactants is stronger, and the adsorption of anionic surfactants is weak. It is related to the charge properties of the adsorbent in the dispersion medium.
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