What metal pigments are commonly used in metal powder coatings
1.1 Pearlescent Pigment
Pearlescent is a new kind of pearl luster produced by natural mica thin skin covered with metal oxides. It relies on light refraction, reflection and transmission to show color and brightness, making the appearance of the coating more brilliant and shining. Pearlescent powder shows different effects in use with different particle sizes.
Generally speaking, the bigger the particles are, the stronger the scintillation effect is, and the weaker the covering power to the background color is. On the contrary, the smaller the particles are, the stronger the covering power to the background color is, and the softer the luster is. However, the coarse particle size of pearlescent powder will lead to gravel on the surface of the coating, which will affect the smoothness of the coating, so the coarse pearlescent powder is not easy to add too much.
1.2 aluminum powder
Aluminum powder is commonly called aluminium silver powder or silver powder because of its silver-white metallic luster. Its chemical composition is actually "aluminium" rather than "silver". There are two main categories: floating silver and non-floating silver.
(1) Silver floatation is treated by stearic acid, which is easy to accumulate on the surface of the film and is easily affected by corrosive media. The smaller the particle size, the stronger the metal sense and the stronger the covering power. However, when the amount of silver is too high, it is easy to produce the phenomenon of powder spitting and blocking the gun head. Therefore, for silver floatation whose particle size is less than 10um, the amount of silver added should not exceed 1%.
(2) Non-floating silver is usually coated with silicon dioxide and acrylic resin, which can be evenly and parallel distributed in the whole coating. Because the aluminum powder is coated with resin, it has good oxidation resistance, wear resistance, good weather resistance, acid-alkali resistance, and no fingerprint. The surface of non-floating silver film is bright, and the color can be adjusted from the bottom powder, but the amount of added silver is larger than that of floating silver, and the effect of metal is stronger than that of floating silver.
1.3 Copper and Gold Powder
Copper and gold powder is pure and bright in color and strong in metal sense, but its weatherability and temperature resistance are poor. At present, it is seldom used in external powder coatings for aluminium profiles.
Application of 1.4 Metal Pigment in Powder Coatings
The formulation composition of metal powder coatings is similar to that of ordinary powder coatings. The formulation design follows the principles of simple manufacture, stable spraying and excellent performance. In the formulation design of metal powder coatings, the fewer kinds of metal pigments, the better. It is advisable to use the least amount of metal pigments to achieve the best covering power.
In order to achieve a certain metal effect, improve film performance or control cost, formula design can be based on the particle size and properties of metal pigments, using pearlescent powder and pearlescent powder, pearlescent powder and silver powder, silver powder and silver powder mixed. Because the float silver is not modified, its alkali resistance is very poor, so it is not suitable to be used alone.
When pearlescent powder is mixed with silver powder, the dosage is not easy to exceed 1.5%. Because most metal pigments will destroy and break their structures during extrusion, so that the metal effect is not obvious or no metal effect. Therefore, metal powder coatings are mainly made of metal pigments and ordinary powder coatings, which are bonded by bonding process to achieve the shining effect of metal decoration.
The article is from Metal Powder Coatings: http://www.xinliqiao.com/