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Color coated steel plate, commonly known as color steel plate, cold rolled steel plate plated with other metal non-metallic or alloy (zinc, aluminum, magnesium, manganese, silicon, etc.) as a substrate, after the surface treatment of the transformation (degreasing, phosphating, chromate), coated with an organic coating by baking made of lightweight, high strength, bright colors, durability and other characteristics. Widely used in construction, home appliances, decoration, automobile and other fields.

The strength of color steel depends on the substrate material and thickness, and the durability depends on the plating, surface coating and processing technology, and the coating has polyester coating (PE), fluorocarbon coating (PVDF), silicone-modified coating (SMP), high marble-resistant coating (HDP), propionic acid coating, polyurethane coating (PU), and plastisol coating (PVC).

etc. The coating structure has two coatings and one baking, two coatings and two baking, etc. The maintenance-free service life can be 10-30 years according to the different environmental atmospheres.

Coating structure

Upper surface Lower surface

Primary coating No coating 1/0

Primary coating Primary coating 1/1

Secondary coating No coating 2/0

Secondary Coating Primary Coating 2/1

Secondary Coating Secondary Coating 2/2

Commonly used coatings

1、Polyester (PE, Polyester)

PE coating for the material has good adhesion, color coated steel is easy to process molding, inexpensive and many products, color and gloss of the choice of a large margin. Polyester coating on UV resistance and film chalking resistance, and not ideal, so the use of PE coating still need to be subjected to some restrictions, generally used in air pollution is not serious areas or the need for multiple molding and processing of products.

2、Silicone Modified Polyester (SMP, Silicone Mobified Polyester)

Because polyester contains active base -OH/-COOH, very easy and other polymer chemistry and reaction, in order to improve the PE sunlight resistance and chalking, to maintain the color and heat resistance of Silicone resin for the denaturation reaction, and PE denaturation ratio can be between 5% -50%, SMP to provide a better durability of the steel plate, and its corrosion resistance can be as long as 10 years! SMP provides steel plate with better durability, and its corrosion protection life can be up to 10-12 years, of course, its price is also higher than that of PE, but due to the adhesion of Silicone resin to the material and the processing of molding is not ideal, so SMP color coated steel is not applicable to occasions requiring multiple molding processing, most of which are used for building roofs and exterior walls.

3、High durable polyester (HDP, High durable Polyster)

For PE and SMP shortcomings, the British HYDRO company (now acquired by BASF), Sweden's BECKER, etc. in the early 2000's its development can reach PVDF coating 60-80% weathering HDP polyester coatings, and is better than ordinary silicone-modified polyester coatings, and its outdoor weathering up to 15 years. High weathering polyester resin in the synthesis of monomers containing cyclohexane structure to achieve the flexibility of the resin, weathering and cost balance, the use of non-aromatic polyalcohols and polyacids to reduce the resin on the absorption of UV light, to achieve high weathering performance of the coating. The addition of UV absorbers and site-blocking amines (HALS) to the coating formulation improves the weathering performance of the paint film. High weathering polyester coil coating has been recognized by the market abroad, the coating is very cost-effective.

4, PVC Plastisol (PVC Plastisol)

PVC resin has good water resistance and chemical resistance, generally coated with high solids, the coating thickness of l00-300μm, can provide smooth PVC coating film or light embossing treatment for embossing film; as PVC coating film for thermoplastic resin, has a high film thickness, and can provide good protection of steel plate. But PVC heat resistance is weak. In the early days in Europe to use more, because of its environmental attributes are relatively poor, the current use of less and less.

5, PVDF

Due to the chemical bond of PVDF and the chemical bond, there is a very strong bond energy, so the coating has a very good corrosion resistance and color retention, in the construction of industrial color coated steel coatings, is among the highest level of products, and molecular weight and for the straight bond structure, so in addition to resistance to chemicals, mechanical properties, UV resistance and heat resistance is also outstanding. In general environment, its anti-corrosion life can reach 20-25 years. In recent years, fluorine resin copolymerized with trifluoroethylene chloride and vinyl ester monomer has begun to prevail in China, which is used in large quantities in the exterior walls and metal panels of buildings. Due to the use of easily hydrolyzable vinyl ester monomer and the fluorine content is about 30% lower than that of PVDF, so there is a certain gap in its weathering resistance compared with that of PVDF. The fluorocarbon coating produced by Baosteel has a coating PVDF content of not less than 70% (the others are acrylic resins).