Description
PPGI Coils (Pre-Painted Galvanized Iron Coils)
Base Material
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Substrate: Hot-Dip Galvanized Steel (HDG)
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Galvanization Layer: Typically zinc (Z) or zinc-aluminum alloy (Galvalume, AZ).
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Purpose of Galvanization: Provides corrosion resistance by sacrificial protection — the zinc layer corrodes instead of the steel.
Coating Process
The process is usually done on a continuous coil coating line (CCL):
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Surface Preparation: Cleaning, degreasing, and chemical pretreatment to ensure coating adhesion.
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Primer Application: One or both sides are coated with a primer layer.
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Topcoat Application: Using polyester, SMP (silicone-modified polyester), PVDF, polyurethane, or other specialized paints.
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Baking & Cooling: Each coating layer is baked in an oven, then cooled.
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Finishing: The coils are rewound and sometimes given a protective film for transport.
Common Coating Types
| Coating Type | Features | Typical Use |
|---|---|---|
| Polyester (PE) | Economical, good color range, moderate durability | Roofing, walls, and decorative panels |
| Silicone-Modified Polyester (SMP) | Better UV resistance, chalk resistance | Exterior building panels |
| Polyvinylidene Fluoride (PVDF) | Excellent weather, UV, and corrosion resistance | High-end architectural projects |
| High Durability Polyester (HDP) | Long life, good mechanical properties | Industrial roofing, coastal areas |
Typical Specifications
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Thickness: 0.15 – 1.2 mm
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Width: 600 – 1250 mm
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Coating Thickness:
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Zinc layer: 60–275 g/m² (per side, total both sides)
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Paint layer: 5–20 μm (primer), 15–25 μm (topcoat)
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Colors: RAL chart or custom
Advantages
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Long service life due to combined zinc and paint protection.
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Attractive finish — a wide range of colors and glosses.
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Easy to transport and install.
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Good formability for bending, pressing, or roll forming.
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Environmentally friendly coatings are available.
Applications
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Construction: Roofing sheets, wall panels, garage doors, and ceiling panels.
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Home Appliances: Refrigerator backs, washing machine bodies, microwave oven panels.
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Furniture: Cabinets, shelving.
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Transport: Shipping containers, vehicle panels.
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Industrial: Agricultural silos, cold storage rooms.
