The dryer is an important additive in paint production. It can accelerate the oxidation, polymerization, and drying of unsaturated oils to achieve fast drying. There are several explanations for the drying mechanism:
* The metal in the drier is reduced to a low atomic valence, and the antioxidant is oxidized, thereby accelerating the oxidation of the oil;
* The drier can accelerate the destruction of the hydroperoxidative bond formed by the oxygen absorption of the oil film, form a stable oxygen bond, and the other unsaturated bonds of the oil will be directly polymerized, reducing the required amount of oxygen;
* The drier can absorb the oxygen in the air and give it to the oil film, reducing the difficulty of the oil film absorbing oxygen. Dryers are more effective when used in combination than when used alone.
Lead salt and manganese salt are the two types of most used traditional paint driers, but they are not the most suitable materials. Among them, the amount of lead salt used accounts for 1/3 of the total paint drier, which causes serious poison and pollution to the human body and the environment; while manganese salt has a dark color and is not suitable for drying light-colored paint. Therefore, rare earth paint driers have become a choice with better comprehensive performance among many paint driers.
Rare earth paint driers can not only replace traditional lead, zinc, calcium, magnesium, and other auxiliary driers, but also replace 50% of cobalt main driers. They can overcome the defects of skinning and wrinkling caused by cobalt drier. The new research results show that the cobalt/cerium or cobalt/mixed rare earth drying system can achieve a better drying effect. Another important reason for the rapid popularization and application of rare earth paint driers is that adding an appropriate amount of rare earth can improve the quality of the paint, so that its color, drying time, hardness index, etc. have been greatly improved. In general, rare earth driers have the advantages of low price, can improve the color of coatings, increase the degree of cross-linking of coatings, and reduce environmental pollution.