References:
The characteristics and main uses of metallic powder coatings (referred to as metallic powder) are widely used in decorative coatings, which is the mainstream of fine arts powder at present. There are many kinds of metal pigments that can be used in powder coatings, which can be divided into four categories, namely, aluminum silver powder pigment, pearlescent pigment, copper gold powder pigment and other metal pigments (such as nickel powder, stainless steel powder, etc.). ). Each metal pigment also contains products of many shades. After being coated on the powder, the color of the powder is rich, which greatly enriches the variety and decoration of the powder coating. Metal powder is now mainly used in indoor and outdoor metal furniture, lamps, handicrafts, range hoods, baby carriages, sports equipment and other industries.
Aluminum silver powder: aluminum pigments are divided into floating and non-floating types. Adding floating aluminum powder to powder coatings can form a continuous phase on the coating surface after baking, and sometimes it has a mirror effect.
Flash non-floating aluminum powder: This aluminum powder usually has a particle size of > 20μ m, and the surface is generally coated, and the coating material is mainly silica gel. The coarser the particle size of non-floating aluminum powder, the better the scintillation effect. Because of the coating on its surface, it has good acid and alkali resistance and certain outdoor durability. Powder coatings without floating aluminum powder can be sprayed on high-demand workpieces such as washing machine shell and motorcycle engine shell. The addition ratio of post-mixed non-floating aluminum powder is very wide, and the dosage of 10% has little effect on powder sprayability.
Suspended aluminum powder is widely used in powder coatings. Floating aluminum powder is mostly flaky under high-power microscope, and the average particle size is generally less than 20 μ m. The smaller the particle size, the stronger the metallic feeling and the greater the hiding power. The strongest metallic feeling should be the chromium plating effect, and the metal powder with this effect is the most popular in the market at present. The development and production of powder coatings with chromium plating effect must start with the selection of base powder formula and aluminum powder. The following formula can be used as a reference.
Remarks on raw material name
DSM resin, acid value 55 mg KOH/ g.
E- 12？ 25? Epoxy resin,
GLP50？ 35? flatting agent
Benzoin 0.5 defoamer
TiO2 3.5？ Rutile titanium dioxide
0.5 wax? Polyethylene wax
BaSO4 2 1？ Ultrafine barium sulfate
CBlack？ 0.00 12 carbon black
This formula is chosen because the melt viscosity of the resin is very small, and the base powder produced by compatibility with E- 12 epoxy has high leveling and high gloss. The main function of wax is to improve the scratch resistance of powder surface.
In order to get the mirror effect, it is necessary to choose appropriate aluminum powder, and the general addition ratio is 1.5%. If the dosage is too high, it is easy to spit powder and block the spray gun head. If the dosage is too low, there will be no mirror effect.
For other particle sizes of floating aluminum powder (mostly in the range of 10~20μm), the addition ratio of 1.5%~2.0% can also get very good silver effect. When the amount of this aluminum powder is small (such as < 1%), because the amount of aluminum powder is too small to completely cover the base powder, blooming often occurs, and sometimes tiny stripes appear. ?