Wax additives for powder coatings are classified according to their chemical composition: polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, etc. In terms of compatibility and cost performance, polyethylene wax is better and can meet the general requirements for hardening and scratch resistance, thus it is widely applicable. In terms of hardening and scratch resistance, Teflon wax is the best and the price is high.
In addition to hardening and scratch resistance, some waxes also have a certain degree of matting, such as polypropylene wax, which can be used as a substitute for matting agent in powder coatings that do not require high matting effect. However, at this time the addition is generally greater than 2%, and sometimes the coating film has obvious wax particles precipitated.
In the application, the wax powder is mostly compound type, of which there are also two methods of using before adding and after mixing. The post-mix wax is a very small particle size of micronized wax, and large particles of wax are mixed with raw materials and extruded together.
1. Adding 1% or less of flake polyethylene wax in the formula can improve the output and reduce the mechanical wear when extruding, especially in the case of more fine powder, the effect is obvious.
2. Adding 0.5-0.8% of polyethylene and amide mixed wax in the formula can improve its dry powder fluidity, and the powder will come out evenly without blocking the gun.
3. The smoothness, scratch resistance, degassing, water resistance, leveling and reducing the gloss of the coating film after adding.
4. Excellent hardening and wear resistance, more expensive. Powder coatings are more often used in fluorine wax (polyethylene wax with a certain amount of polytetrafluoroethylene wax), adding 0.2-0.8% of the total amount of the formula. The addition of this kind of wax powder also has a direct effect on the anti-handprint of the flash silver formula.
5. Hardening wax powder is mostly high melting point polyethylene wax, or add part of the higher melting point of polypropylene wax, because of its cheap and non-smoking, the amount of addition in 0.5-1.5%.
6. Ordinary wax powder has improved the leveling of the coating film, or improve the fullness, but according to the variety and the amount of different, have part of the matting.
Different kinds of wax between each other, can make the mechanical properties of the coating film can be significantly improved, but in the actual use of some use of misconceptions, such as: transfer formula in a small amount of wax added to facilitate the tearing of the paper, the amount is too large, the coating texture transfer is not clear; some particle size coarse wax powder plus, the surface of the coating will form shallow shrinkage or texture points and other defects; there are some such as amide wax added too much, the surface of the coating film is easy to appear fog shadow, causing serious loss of light, etc. Therefore, wax powder in the actual use of a variety of chemical components to understand some of the physical properties of wax powder, the second is in the wax powder in the common, appropriate control of its addition, the maximum does not exceed 2%.
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