Лако-красочные материалы — производство

Figure 5.36 gives an overview of how the pigment properties of hematites are related to their particle sizes. Transparent iron oxides consist of nanoparticles with a primary particle size of 0.001 to 0.05 pm and are supplied in the yellow to red color range. Their applications include effect coatings (mixed with effect pigments), pure yellow and red shades (mixed with titanium dioxide), and wood protection coatings. Suitable binders are baking finishes (transparent yellow iron oxide <180 °C), water-based binders, acrylic-isocyanate systems, acid-curing systems, amine-curing systems, and air-drying binders. Only transparent red iron oxide can be used to color transparent plastics because of the high heat stability required. Since this pigment is extremely difficult to disperse, it is best applied in the form of a preparation. The pigment particles of transparent iron oxides are two to three powers of ten smaller than those of opaque iron oxides. Depending on the manufacturing process, the primary particles

are needle-shaped (precipitation process) or spheroidal (iron pentacarbonyl process).

The particle sizes of opaque and transparent iron oxides are compared in Figures 5.37 and 5.38.

Fig. 5.37 Red iron oxide, transparent (precipitation process) [5.186].

Fig. 5.38 Red iron oxide, opaque [5.187].

5.4.1.1