The prepainted steel sheet in coil is a product obtained by subjecting a hot-dipped galvanized steel sheet, and galvalume steel sheet, or an aluminum sheet to a surface chemical treatment (coating), followed by baking and curing.

The total thickness of the pre-panted galvanized steel coil is composed of the base steel – coating -primer – top paint – protective layer thickness. The top paint thickness is 10-25μm, and the back paint thickness is 5-20μm. The thinner the base steel thickness, the higher the price of the ppgi steel coil, because the processing cost becomes higher.

Usually, the paint coating material is polyester (PE) and the color of the back paint is white grey. The color can be customized according to the RAL color card or customer samples. Special patterns can be made, such as wood grain, flower print, camouflage, brick.

PPGI is also known as prepainted galvanized steel coil and color coated steel coil, with a hot dip zinc coated steel sheet substrate. PPGL is also known as prepainted galvalume steel coil, with a galvalume steel sheet as a substrate.

PPGI Coil Production Process

Unrolling – Stitching machine – Entrance loop – Pretreatment – Initial coating – Bake – Cool down – Fine coating – Bake – Embossed film – Export loop – Inspection station – Cut – Coiling
In the above process, if the cleaning degreasing process is not handled well, the adhesion of the primer of the color coated plate to the galvanized sheet is not good, and it is easy to cause the topcoat of the color coated steel coil to fall off during the press forming process.

PPGI Sheet Coating Layer

Top (Finish) Coating (PE/HDP/PVDF, etc.)Primer CoatingPre Treatment (Chromate Coating)Plating Layer (Zn, AL, 55%AL+Zn)Base Metal (Cold Rolled Steel Sheet)Plating Layer (Zn, AL, 55%AL+Zn, Sn, Cr, etc.)Pre Treatment (Chromate Coating)Functional Painting (Epoxy, Polyester )