Electrostatic spraying requirements for powder coatings

Thin powder coatingsgenerally refer to coatings with a thickness of less than 35 (or 30)u as thin powder coatings that are about half the thickness compared to coatings of 50-70u as thin powder coatings must have a number of characteristics.
First of all, with excellent covering force in the thickness of about 30u to be able to cover the substrate well must increase the share of coloring pigments (e.gtitanium white) in the case of thin coating to obtain good leveling and must reduce the coating's base ratio (in other words, increase the share of resin in the formulation); Secondly, the resin suitable for thin-layer powder coating should have a lower melting viscosity on the one hand can fully wet the substrate and the face filler on the other hand has good levelingWith this characteristic to analyze polyester and mixed powder coating formulation its melting viscosity is high on the pigment's wetting is not suitable; Combined with China's national conditions, acrylic polyurethane resin is difficult to popularize epoxy resin plus excellent performance curing agent is a more feasible development pathThe particle size distribution of powder is also a very important feature for thin powder coatings If the maximum thickness is 30u then the maximum particle size of the powder should be less than 60u (about 260 holes) so to strengthen grinding to make the powder thinnerEpoxy acrylic resin and polyurethane resin to take into account the contradiction of viscosity and glass temperature is also a more difficult problem to solveGenerally speaking, the viscosity of small glass temperature will also be low; the viscosity is small to help the coating leveling but the low glass temperature makes the powder easy to group storage stabilitypoorThin layer powder coating in China is still in the development stage of the road is still a long way to go, but in any case this is a development directionAlthough the production cost of thin powder coating is high and high price, but ultimately for the user can save the cost of powder 15-20%IIHeavy anti-corrosion powder coatingheavy anti-corrosion powder coating has better anti-corrosion capacityBecause of the higher corrosion resistance required, the choice of line-type phenolic epoxy resin Line phenolic epoxy resin and commonly used BPA series epoxy resin has a great difference in its molecular structure to line phenolic resin as the main chain of each molecule The chain contains more than three epoxy bases because their molecules have three degrees of performance (bisphenol A series epoxy resins have only two degrees of performance) so its curing material cross-linking density is high when curing At present, the use of more in foreign countries mainly used in oil and gas chemical pipeline coating can also be used in chemical plants have heavy anti-corrosion requirements of the metal parts coating In China, the powder coating of this species is still in the initial stage of use is not much but has good prospects for development