1.What are the standard production processes for color-coated steel coils?
Loading and Uncoiling: Cold-rolled coils (or more commonly, corrosion-resistant galvanized cold-rolled coils) are loaded onto the production line.
Pre-treatment (Chemical Cleaning and Passivation):
Degreasing: Removing grease and dust from the surface of the cold-rolled coils.
Water Washing.
Chemical Conversion Treatment (e.g., phosphating or chromating): Forming a dense crystalline conversion film on the metal surface. This film acts as a "bridge," greatly enhancing the adhesion between the substrate and subsequent coatings and improving corrosion resistance. This is the first key to successful "lamination."
Primary Coating/Uncoating:
After being dried in the oven, the substrate is first coated with a primer. The primer's main functions are rust prevention, corrosion resistance, and good adhesion to the substrate and topcoat.
After coating, the substrate is baked and cured in an oven.
Topcoat/Finish Coating:
The topcoat is applied over the cured primer. The topcoat determines the final appearance and performance of the product, including color, gloss, weather resistance, and chemical resistance.
The product is then baked in an oven for further curing.
Post-treatment (optional):
Protective Film: Protects the surface from scratches during transport and processing.
Embossing: Textured rollers are used to emboss patterns such as wood grain and stone grain before or after the coating has cured.
Winding and Packaging: The final color-coated coil product is then produced.
2.What are the process and characteristics of adhesive bonding?
Process: A high-performance structural adhesive (such as epoxy or polyurethane adhesive) is evenly applied to the inner surface (or core material) of the color-coated sheet. Then, it is laminated with a cold-rolled sheet (or aluminum sheet, fire-resistant board, etc.) serving as the backing plate using a laminator under specific pressure and temperature.
Features: Suitable for flat or simply curved panels. The key is the selection of the adhesive, which must consider bonding strength, durability, and temperature resistance.
3.What are the process and characteristics of hot-pressing composite method?
Process: If the core material is a thermoplastic material (such as PVC or PE foam), the color-coated sheet, core material, and backing sheet can be stacked and fed into a hot press. Heating melts or softens the surface of the core material, bonding it to the upper and lower metal sheets under pressure.
Features: High bonding strength; commonly used in manufacturing sandwich panels with metal facing layers (such as color-coated steel rock wool panels and polyurethane-sealed sandwich panels).
4.What are the process and characteristics of the flame composite method?
It is mainly used for on-site foamed polyurethane (PU) sandwich panels. The color-coated sheet serves as the upper and lower layers, with mixed foamed polyurethane raw materials injected in the middle. During the foaming and expansion process, it firmly bonds to the metal sheet and cures.
5.What are the process and characteristics of mechanical biting method?
Process: A special roll forming process is used to interlock the color-coated sheet and the backing panel at the edges or specific locations, sometimes supplemented with structural adhesive for sealing. Commonly used in some composite duct panels or decorative panels.
Features: No glue or heating is required; the bonding force is mechanical.