The color-coated steel strip using hot-dip galvanized steel strip as the base material is not only protected by the zinc layer, but the organic coating on the zinc layer plays a covering and protective role to prevent the steel strip from rusting, and its service life is longer than that of the galvanized strip, about 1.5 times.
Color-coated coil is based on hot-dip galvanized sheet, hot-dip galvanized sheet, electro-galvanized sheet, etc. After surface pretreatment (chemical degreasing and chemical conversion treatment), one or several layers of organic coatings are applied on the surface, and then A product that is baked and cured. It is named after the colored steel coils coated with various colors of organic coatings, referred to as color-coated coils.
v Coating structure type
2/1: Coat the upper surface twice, coat the lower surface once, and bake twice.
2/1M: Coat the upper and lower surfaces twice and bake once.
2/2: Coat the upper and lower surfaces twice and bake twice.
v Application of different coating structures:
2/1: The corrosion resistance and scratch resistance of the single-layer back paint are poor, but it has good adhesion.
to be applied to sandwich panels.
2/1M: The back paint has better corrosion resistance, scratch resistance and formability, and has good adhesion
Suitable for single-layer profiled panels and sandwich panels.
2/2: The corrosion resistance, scratch resistance and processability of the double-layer back paint are better, and most of them are used for single.
Laminated panels, but their poor adhesion, should not be used for sandwich panels.
Color coated substrate classification
Hot-dip galvanized substrate
The product obtained by applying an organic coating on a hot-dip galvanized steel sheet is a hot-dip galvanized color-coated sheet. In addition to the protective effect of zinc, the hot-dip galvanized color-coated sheet also has the function of insulating protection and preventing rust, and the service life is longer than that of the hot-dip galvanized sheet. The zinc content of the hot-dip galvanized substrate is generally 180g/m2 (double-sided), and the highest galvanized amount of the hot-dip galvanized substrate for building exterior is 275g/m2.
Hot-dip galvanized substrate
Hot-dip galvanized steel sheet (55% Al-Zn) is used as the newly coated substrate, usually containing 150g/㎡ of aluminum and zinc (both sides). The corrosion resistance of hot-dip galvanized sheet is 2-5 times that of hot-dip galvanized sheet. Continuous or intermittent use at temperatures up to 490°C will not severely oxidize or produce scale. The ability to reflect heat and light is twice that of hot-dip galvanized steel, and the reflectivity greater than 0.75 is an ideal building material for saving energy.
Galvanized substrate
The electro-galvanized sheet is used as the substrate, and the product obtained by coating with organic paint and baking is an electro-galvanized color-coated sheet. Since the zinc layer of the electro-galvanized sheet is thin, the zinc content is usually 20/20g/m2, so this product is not suitable for use. Make walls, roofs, etc. outside. However, because of its beautiful appearance and excellent processing performance, it is mainly used in home appliances, audio, steel furniture, interior decoration, etc.
Type of coating
1. Polyester
Good adhesion, rich colors, wide range in formability and exterior durability, moderate chemical resistance, low cost.
2. Silicon modified polyester
That is (SMP), the coating film has good hardness, wear resistance and heat resistance, as well as good external durability and chalking resistance, gloss retention, general flexibility, and medium cost.
3. High durability polyester
That is (HDP), excellent color retention and UV resistance, excellent outdoor durability and chalking resistance, good film adhesion, rich colors, excellent cost performance.
4. Polyvinylidene fluoride
Namely (PVDF), excellent color retention and UV resistance, excellent outdoor durability and chalking resistance, excellent solvent resistance, good formability, dirt resistance, limited color, high cost.
