Powder coating is a coating that contains 100% solids and is coated into a film in the form of powder. It uses air as a dispersion medium. Epoxy powder coating is a kind of thermosetting powder coating with corrosion resistance and toughness. It has the earliest application and rapid development. It is composed of epoxy resin, pigments and fillers, additives and curing agents. The preparation of epoxy powder coatings is the only method to produce thermosetting powder coatings internationally, that is, melt mixing extrusion method-mixing, melt mixing extrusion, and fine crushing.
The epoxy resin requirements of epoxy powder coatings: the epoxy equivalent should be a solid resin between 700-100, and the molecular weight distribution is narrow; at its curing temperature, the melt viscosity is low, easy to level, and the coating film is flat and thin ; Good dispersion of pigments and fillers.
The curing agents for epoxy powder coatings mainly include dicyandiamide, dicyandiamide derivatives, acid anhydrides, imidazoles, cyclic ethers, phenolic resin polyester resins, and boron trifluoride amine complexes. In industry, dicyandiamide, imidazoles and cyclic ethers are generally used.
Features of epoxy powder coating
①Epoxy powder coating has strong adhesion, especially to metals;
②The paint film of epoxy powder coating has good mechanical properties, high hardness, scratch resistance and corrosion resistance;
③Epoxy powder coating has low melt viscosity, good leveling, and the coating film is basically free of defects such as pinholes and shrinkage;
④Epoxy powder coating has a wide variety of colors and can be formulated with matte, shiny, pattern, hammer, etc.;
⑤Epoxy powder coating can be coated with a film thickness of 50-300μm at one time, and the uncoated powder can be recycled;
⑥The coating equipment of epoxy powder coating requires high requirements, large investment, and complex and precise equipment.
Main varieties of epoxy powder coatings
The types of epoxy powder coatings mainly include epoxy bright powder coatings, epoxy matte powder coatings, epoxy matte powder coatings, epoxy semi-gloss or flat powder coatings, epoxy electrophoretic powder coatings, antibacterial, conductive, Functional epoxy powder coatings such as flame-retardant type and art type.
Application range of epoxy powder coating
Epoxy powder coatings are not suitable for substrates with poor heat resistance, because their curing temperature is higher, up to 140 ℃, and can be used for decorative protection of electrical switch cabinets, electronic instruments, metal silicon boxes, etc., motor rotors or Electrical insulation protection of copper bars, anti-corrosion and anti-rust of kitchen utensils, auto parts, ships, building materials, underground facilities, etc.