The working principle of polyurethane powder coating mainly involves chemical reactions and physical changes.
Polyurethane powder coating is usually composed of polyisocyanate and polyol (such as polyether or polyester polyol). During the spraying process, these components are mixed and a rapid chemical reaction occurs to form urethane bonds. This process is called polymerization.
In addition, in order to improve the performance of the coating, additives such as catalysts, surfactants, flame retardants and foaming agents are also added. The foaming agent produces gas (usually carbon dioxide) during the reaction process, which is captured by the newly formed polyurethane foam to form foam cells.
Features of polyurethane powder coatings include:
- Excellent leveling: Polyurethane powder coatings have low viscosity when molten and flowing, especially before the sealant is unsealed, no chemical reaction occurs, which provides sufficient leveling time for the powder coating, so the coating has excellent leveling.
- Good physical and mechanical properties: Polyurethane powder coatings have excellent weather resistance, chemical corrosion resistance and water resistance, high coating hardness and strong adhesion.
- Wide application areas: Due to the above advantages, polyurethane powder coatings are widely used in household appliances such as refrigerators, washing machines, air conditioners, as well as high-end furniture, automobiles, motorcycles and other industries.
Construction methods and environmental requirements:
- Preparation before construction: The surface of the substrate must be clean, oil-free and moisture-free to ensure good adhesion between the foam and the substrate.
- Environmental factors: Ambient temperature and humidity will affect the curing speed and final performance of polyurethane powder coatings. Under suitable environmental conditions, polyurethane spraying can cure faster to form a uniform and dense foam layer.