For the shortcomings of PE and SMP, British hydro company (now purchased by BASF) and Swedish Becker developed a 60-80% weather resistant HDP dip coating that can achieve PVDF coating in the early 2000, and it is superior to ordinary silicon modified
polyester coating, with outdoor weather resistance of 15 years. In the synthesis of high weather resistant polymer resin, the monomer with cyclohexane structure is used to achieve the balance of flexibility, weather resistance and cost of the resin,
and the polyol and polyacid without aromatic group are used to reduce the absorption of UV light by the resin, so as to achieve the high weather resistance of the coating. UV absorbers and HALS} were added to the coating formulation to improve the
weatherability of the film. High weather resistant polyester coil coating has been recognized by the market abroad, and the cost performance of the coating is very outstanding.
Baosteel silicon modified polyester (SMP)
Because polydips containing active group Oh / - COOH are very easy to react with other polymers, in order to improve the sunlight resistance and pulverization of PE, the silicone resin with excellent color
retention and heat resistance is used as the modification reaction, and the modification ratio with P can be between 5% and 50%. SMP provides better durability of steel plate, and its corrosion resistance period can be up to 10-12 years, of course, its
price is higher than PE, However, due to the unsatisfactory adhesion and processing formability of silicon resin to materials, SMP color coated steel plate is not suitable for occasions requiring multiple molding and processing, most of which are used
for star top and outer wall of buildings.
PVF (polyvinylidene fluoride) of Baosteel
Due to the strong bond energy between the chemical bond and chemical bond of PVDF, the coating has very good corrosion resistance and color retention. In the
color coated steel plate coating for construction industry, it is the most advanced product with large molecular weight and straight bond structure. Therefore, in addition to chemical resistance, mechanical properties, cable resistance and heat resistance
are also very special. In general, the anti-corrosion period can be as long as 20-25 years. In recent years, fluorine-containing resin copolymerized with vinyl trifluorochloroethylene and vinyl ester monomers has become popular in China, which has been
widely used in exterior walls and metal plates of buildings. Because the content of vinyl ester monomers and fluorine which are easy to hydrolyze is lower (about 30%) than PVDF, there is a certain gap between its weatherability and PVDF. The PVDF content
of the fluorocarbon coating produced by Baosteel is not less than 70% (others are propionic acid resin).