An important standard for the selection of pigments in powder coatings

Powder coating is not liquid, but a kind of powder coating The manufacture of powder coating is totally different from the traditional solvent coating or water-based coating The production process and equipment are similar to plastic processing to some extent, and the solvent is not needed in the application Therefore, compared with traditional coatings, there are different requirements for pigments Easy dispersion is an important requirement of powder coatings for pigments The dispersion of pigments in powder coatings is fundamentally different from that of liquid coatings in terms of technology or state of dispersed materials, and there is no comparability at all The retention time of the pre dispersed materials in the melt mixing equipment is very short, and it is very difficult to wet the pigment, so the dispersibility of the pigment becomes particularly important Generally, the pigments with good dispersibility in polyolefin plastic particles meet the requirements of powder coating The heat resistance of powder coating to pigment is mainly based on the following two considerations: on the one hand, the pigment must be able to withstand at least 210 ℃ for about 12 to 15 minutes of coating heating, melting, leveling and drying process; on the other hand, the powder coating on the surface of some end consumer products (barbecue rack, stove, etc.) must also withstand extremely high temperature The rheological system of powder coating requires that the pigment can not weaken the fluidity of the melted coating Only by ensuring the good fluidity of powder coating under low shear force, can the dense, smooth and continuous coating be formed in the process of heating, melting, leveling and curing after coating The coating thickness of the powder coating is generally in the range of 40 to 70 microns Only the excellent covering performance of the pigment can ensure the nearly perfect appearance of the powder coating In the field of outdoor decorative coating, the powder coating must go through at least one year's Florida exposure test, and the coating must maintain good color stability and light retention This puts forward high requirements for light and weather resistance of pigments The chemical resistance of powder coating mainly depends on its application, for example, the powder coating applied on the washing machine shell must have alkali resistance There are several kinds of pigments suitable for powder coatings: Yellow 53 Brown 24 blue 28 blue 36 and bismuth vanadium molybdenum yellow 184 Pigment yellow 34 and red 104 in lead containing pigments And organic synthetic pigment yellow 110; pigment red 112 202 254 255 and 264; pigment purple 19 and 23; pigment blue 60 and 15:1 At present, the pigment preparation after surface treatment (for example, wrapped by urea formaldehyde resin) has also entered the field of powder coating