What is the impact of different types of substrates on color coated sheets?
Color coated sheet basic concept: in the continuous unit with cold-rolled strip, galvanized strip (electro-galvanized and hot-dip galvanized), aluminized zinc, as the substrate, after surface pretreatment (degreasing and chemical treatment), with roller coating method, coated with one or more layers of liquid coating, after baking and cooling the resulting sheet is the coated steel. Nowadays, there are back (primer) and surface (front) paint coatings in China, generally one layer of back paint and two layers of top paint in China, and two layers of both top and back paint in foreign business. Since the coating can have various colors, it is customary to call the color coated steel sheet, also called a color coated coil, colored steel coil, color coated steel strip, etc.
The intrinsic quality of the color coated steel sheet depends first of all on the merits of the plating substrate and the thickness and process of the plating.
Substrate plating types can be divided into the following categories.
1. Cold-rolled sheet. Cold rolled after degreasing cleaning and chemical transformation directly as a color coated substrate and then coated with paint baking molding, the disadvantage is easy to rust, and no anti-corrosion ability
2. Electro galvanized sheet is cold rolled after electroplating after treatment as a color coated substrate, and then coated with paint high-temperature baking molding, the disadvantage is that, because it is cold plating, and thin plating, plating, and cold sheet adhesion is not good enough, after some time easy to dezincification itch, resulting in weakened corrosion resistance. The advantage is that the plating layer is thin, so the surface glossy plating is good. Mostly used in the field of steel windows for home appliances, suitable for indoor use.
3. Hot dip galvanizing is based on the cold sheet after treatment, the steel mill through high-end hot plating technology, the cold sheet on both sides of the surface plating a certain thickness and weight of zinc-silicon alloy, so that it becomes a higher anti-corrosion ability, anti-oxidation ability. Because it is hot plated, the adhesion between the cold sheet and the plating is better, the attached plating is thicker and the surface can have zinc flowers. After the surface of hot-dip galvanizing is brightened, the surface is degreased and cleaned, chemically transformed, and finally coated and baked with a certain thickness of paint to make it a finished product of a color-coated coil. After hot-dip galvanizing as the substrate, the color coated coil is widely used, and is the most used product at home and abroad. They are used in many fields such as outdoor steel construction, mechanical packaging, and home appliances. Its plating weight is more for Z50g, Z80g, Z100g, Z120g, Z140g, Z180g, Z200g, Z220g, Z275g per square, etc. According to the customer’s demand, we can produce customized steel sheets with different galvanization amounts.
4. Hot dip aluminum-zinc plating is based on the cold sheet after treatment, steel mills through high-end hot dip plating technology, the cold sheet on both sides of the surface plating a certain thickness and weight of aluminum-zinc alloy, the content of each component of the standard: aluminum containing 55%, zinc-containing 43.5%, containing 1.5% silicon. This makes it an alloy steel wrapped by aluminum-zinc alloy, which doubles the anti-corrosion and anti-oxidation capacity compared to the previous hot-dip galvanizing. Hot-dip aluminum-zinc plating goes through the same process as hot-dip galvanizing (degreasing and cleaning, chemical transformation, etc.) and is finally coated with a paint of a certain thickness and baked on the surface to make it a finished product of aluminum-zinc sheet color-coated coil.