Table of contents
Table of contents
Air-drying paints have long played a pivotal role in the architectural coatings sector. Traditionally, Cobalt has been a staple drying agent for these paints, but its associated complications are nudging the industry towards other options. Europe’s impending cobalt regulations are intensifying the search for reliable alternatives to Cobalt.
Paint drying in two stages
1. Physical drying
After application, the solvent in the paint evaporates, allowing the paint particles to come together and form a solid film.
2. Chemical drying
The binder compound reacts with air’s oxygen, transforming the paint molecularly to harden and increase durablity.
Creating a durable paint film
Oxidation is key for the paint’s hardening and provides it with lasting durability. The synergy of these stages ensures alkyd paints perform as intended, with the balance between solvent evaporation and oxidation is crucial for a durable paint film.
The chemistry of drying
Below is a brief overview of the chemistry of the paint drying process. It shows the importance of the autoxidation sequence, especially in alkyds:
The paint drying process
Formation of hydroperoxide (oxygen uptake)
Figure 1: Metal driers are instrumental in facilitating the ingress of molecular oxygen throughout the paint's coating. As the drier and oxygen interact, a hydroperoxide compound is formed.
Decomposition of hydroperoxide
Figure 2: The formed hydroperoxide undergoes rapid decomposition, leading to the generation of highly reactive radicals.
Combination with another unsaturated side chain
