Color-coated (prepainted) steel plate is made by applying an organic coating to cold-rolled steel, galvanized steel or galvalume steel on a continuous coil-coating line. The product combines the strength of steel, the corrosion protection of zinc and a decorative, durable paint finish.
1. Production Process
Uncoiling: the base coil is fed into the line;
Pretreatment: degreasing, cleaning and chemical conversion (phosphating, chromating or chromium-free passivation) to prepare the surface and improve adhesion;
Primer coating: a corrosion-inhibiting primer is roll-coated (typically 5–10 μm);
Primer baking: the primer is cured in an oven;
Topcoat: the finish coat is applied (typically 15–25 μm);
Topcoat baking: curing to the final film;
Post-treatment: optional embossing, lamination, printing; cooling;
Recoiling: inspection and recoiling for delivery.
The standard configuration is two-coat two-bake (primer + topcoat, two ovens); one-coat or three-coat lines exist for special products.
2. Coating Systems
| System | Position |
|---|---|
| Polyester (PE) | Economic, general indoor/moderate outdoor use |
| Silicon-modified polyester (SMP) | Better durability and colour retention outdoors |
| High-durability polyester (HDP) | High weatherability at moderate cost |
| PVDF (polyvinylidene fluoride) | Best colour retention and chemical resistance - premium facades, coastal service |
Coating life depends on the system, film thickness and environment (e.g. ISO 9223 corrosivity); no fixed multiple of galvanized-only life should be quoted.
Request Latest Steel Price Today
3. Applications
Construction: roofing and wall cladding, sandwich panels, industrial and commercial buildings;
Appliances: refrigerators, washing machines, dishwashers, HVAC cabinets;
Transport: truck bodies, containers, bus components;
Furniture and office fit-outs, and general light fabrication.
4. Advantages
Lightweight with high strength; direct processing (cutting, bending, roll-forming) without painting;
Zinc plus organic-coating dual protection - the coating isolates the zinc and delays corrosion;
Wide colour and finish range (plain, metallic, embossed, printed).
5.Packaging and Shipping
