Лако-красочные материалы — производство

Phosphate pigments are widely explored as anticorrosive replace­ments for toxic lead and chromate-based pigments. Being white, they are more versatile than chromates. This large group of pig­ments may be classified in the following two subgroups.

Zinc-based phosphates: examples include zinc phosphate, alumi­num zinc phosphate, zinc molybdenum phosphate, aluminum-zinc hydroxyphosphate, zinc hydroxymolybdate phosphate, basic zinc phosphate, zinc silicophosphate and zinc aluminum polyphosphate.

Zinc-free phosphates: examples include aluminum phosphate, dihydrogen aluminum triphosphate, strontium aluminum poly­phosphate and calcium aluminum polyphosphate silicate.

Zinc phosphate

Due to their low solubility and reactivity, these pigments are widely used in different binder systems such as alkyd, epoxy and epoxy esters. Zinc phosphate provides corrosion protection through multiple effects, such as by phosphate ion donation, by creation of a protective film on the anode and by an inhibitive action when used with oleo — resinous binders. Typically, coatings based on these pigments are reported to exhibit poor performance in salt spray or other accelerated tests, while they are found effective in real-world performance. Their typical loading levels are 10 to 30 % in maintenance coatings. Zinc phosphate pigments are often modified by an organic surface treat­ment to the pigment or by blending with other inorganic inhibitors.