Polyurethane lacquer used in wood is divided into varnish and color paint (also called polyurethane enamel), which is a two-component hydroxyl-cured coating.
One component contains the adduct of isocyanate group (-Nc0), and the other component is polyester with hydroxyl group (-OH). When using, mix the two components in a certain proportion, because the ( -NCO) interacts with (-OH) in the polyester to produce a chemical reaction, and the paint film cures rapidly within tens of minutes. This curing method is carried out under normal temperature conditions, and the solvent in the paint is fully volatilized. In terms of its drying performance, it has the side of solvent volatilization and drying, and the side of crosslinking and curing drying. It can be dried naturally at room temperature, and can also be heated and dried by convection with hot air to speed up the drying of the coating. The paint manufacturer divides the two-component polyurethane paint into component A and component B; they are packaged and supplied to users separately. When used, it is formulated according to the proportion. Generally, the ratio of Group A: Group B is 1:1, 4:1, and it is prepared as needed, so as to avoid gelling and scrapping. The paint film of polyurethane Sidang coating is bright, plump and hard; it has good wear resistance, water resistance and solvent resistance; it is also excellent in chemical corrosion resistance, moisture resistance, mildew resistance, and physical and mechanical properties.