NEWS
Selection of coating materials for color steel coils
Currently, the types of coatings used for color-coated steel plates include polyester coatings/fluorocarbon coatings/silicon modified coatings/high weather-resistant coatings/acrylic coatings/polyurethane coatings/plastisol coatings, etc.
1. Polyester coating has good adhesion to materials. Color-coated steel plates are easy to process and shape. They are cheap, have many products, and have a wide range of color choices. Under direct exposure in normal environments, the anti-corrosion life can be as long as 7-8 years. However, in industrial environments or heavily polluted areas, its service life will be relatively shortened. However, the UV resistance and film shatter resistance of polyester coatings are not ideal. Therefore, the use of PE coatings still needs to be restricted. It is usually used in areas with less air pollution or for products that require multiple molding and processing.
2. Because polyester contains reactive groups -OH/-COOH, it easily reacts with other macromolecules and polymers. In order to improve the light resistance and crushability of PE, silicone resin with excellent color retention and heat resistance is used for denaturation reaction, and the denaturation rate with PE can be between 5% and 50%. SMP provides better durability of steel plates, and its anti-corrosion life can reach 10-12 years. Of course, its price is also higher than PE, but due to the unsatisfactory adhesion and processability of silicone resin to materials, SMP color-coated steel plates are not suitable for occasions that require multiple molding processes. They are mostly used in building roofs and exterior walls.
3. High weather resistance polyester coating is better than ordinary silicon modified polyester coating, with outdoor weather resistance of up to 15 years. In the process of synthesizing highly weather-resistant polyester resin, monomers containing cyclohexane structures are used to achieve a balance between resin flexibility, weather resistance and cost. Aromatic polyols and polybasic acids are used to reduce the UV absorption of the resin and achieve high weather resistance of the coating. UV absorbers and sterically blocking amines (HALS) are added to coating formulations to improve the weatherability of the paint film.
4. Plastisol has good water resistance and chemical resistance. It is generally a high solid content coating with a coating thickness of 100-300 μM. It can provide smooth PVC coating or photo-embossing treatment as an embossed coating; since PVC coating is a thermoplastic resin with high film thickness, Therefore, it can provide good protection for the steel plate. However, PVC has poor heat resistance.
5. Due to the strong bond energy between PVDF chemical bonds, the coating has good corrosion resistance and color retention. It is a more advanced product among Baosteel's color steel plate and coil coatings for construction. It has a large molecular weight and direct bonding structure. Therefore, in addition to chemical resistance, its mechanical properties, UV resistance and heat resistance are also outstanding. Under normal circumstances, the anti-corrosion life can be as long as 20-25 years. In recent years, fluororesins copolymerized with chlorotrifluoroethylene and vinyl ester monomers have been widely used in my country and are widely used in building exterior walls and metal panels. Due to the use of easily hydrolyzable vinyl ester monomer, the fluorine content is about 30% lower than that of PVDF, and its weather resistance is somewhat different from that of PVDF.
More News