The process in which the surface coating of the coating changes from a liquid or powder state to an amorphous solid film is called the film-forming process of acrylic resin, or solid propionic acid resin. Acrylic resin mainly relies on the volatilization, melting, condensation, polymerization and other physical or chemical actions of the solvent to form a film. According to different film-forming processes, acrylic resins can be divided into volatile film-forming type and cross-linking film-forming type.
There are many curing methods for acrylic resin, generally divided into three types, namely natural curing, heat curing and radiation curing.
First: Natural curing (or natural drying) is only suitable for volatile acrylic resins, self-curing acrylic resins and catalyst polymerization acrylic resins. The curing speed of the coating film is related to air temperature, humidity and wind speed. Generally, the higher the temperature, the lower the humidity. The better the air circulation, the faster the curing speed. The ultraviolet rays in the sun can promote the curing of the oxidative polymerization type acrylic resin. Natural curing also has requirements for the cleanliness of the air and must comply with environmental protection conditions.
Second: Heating curing is divided into forced drying and drying. Forced drying refers to the coating that is naturally dried by heating. The shrinkage curing time is generally lower, at 60-100*C; drying refers to heating only at a certain temperature Under-curing acrylic resin to make it cured into a film, the temperature is generally above 120 °C. The heating temperature refers to the temperature of the coated surface or the coated substrate, not the temperature of the drying environment.
There are three heating methods: convection, radiation and electric induction. Convection heating uses hot air as the medium. It has the advantages of uniform heating and precise temperature control. It is suitable for drying the coated objects with high coating quality and complex appearance. The disadvantage is that the heating speed is slow. Radiation heating commonly used infrared and far infrared, the radiation is directly absorbed by the object and converted into heat energy, so that the substrate and the coating are heated at the same time, characterized by fast heating speed, high thermal efficiency, and uneven heating. Electric induction heating uses electromagnetic induction to heat metal parts. It is characterized by high heating efficiency and suitable for small metal workpieces.
Third: Radiation curing is a technology that uses ultraviolet light and electron beams to cure the coating.