What is the role of waxes in spray powders? In powder coatings, the wax series is used in many applications, the main function is to improve the hardness and smoothness of the coating, degassing and defoaming, prevent caking, wet and disperse, help leveling, reduce gloss, etc.
1. The types of wax used in powder coatings mainly include: polyolefin wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, etc. Among them, in addition to the above-mentioned commonality of waxes, each has its own advantages, such as cheap polypropylene, good matting effect of polypropylene wax, high hardness of polytetrafluoroethylene, and good degassing effect of polyamide.
2. What can be added to the powder must be micronized wax with good compatibility. The dispersion effect of the powder is good, and it is easier to help leveling; the granular and flake wax can increase the extrusion speed in the powder production.
3. Because there are small molecular substances on the surface of the powder coating substrate, especially for porous substrates such as cast iron, cast aluminum, and zinc-based substrates, this type of wax can solve the problems such as pores caused by the above substrates , coating defects such as bubbles and dents.
4. Some amino-modified polyolefin waxes are of the same type as the leveling agent used in powder coatings, so they have better wetting effect in resin-coated fillers and pigments. The leveling of the surface is thus improved.
5. Basically every kind of wax powder has the effect of improving the smoothness of the powder and increasing the storage stability of the paint. Generally, in consideration of cost, the amount added in the formula is 0.2-0.5% (wt), and the wax powder used is relatively popular. One thing to note is that the production process of low-grade wax and impurities have a negative effect on powder coatings. The impact cannot be ignored. What’s more, when the formula with certain types of wax is added, the peculiar smell and smoke will be particularly strong when baking, which is not conducive to environmental protection and safety. In addition, a small amount of polyethylene wax is added to prevent it from sticking to the cooling roller after extrusion.
Wax additives are often used in the production of powder coatings, mainly for matting, leveling, and scratch resistance. The powder coatings are mainly polymer modified and synthetic waxes, and is solid.
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