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prepainted steel sheet in coils
Mar 09, 2018


The base sheet of prepainted steel coil is hot dip galvanized sheet, hot dipped galvanized sheet, electro-galvanized sheet, etc. After the surface is pre-treated (chemical degreasing and chemical conversion treatment), the surface is coated with one or more layers of organic coatings.



Features of prepainted steel coil is light weight, beautiful appearance and good anti-corrosion performance, and can be directly processed easily. It is mainly used in advertising, construction, household appliances, electrical appliances, furniture industry and transportation industry. 


Base sheet

1. Hot dipped galvanized steel sheet

The most normal material for prepainted steel coils.

2. Hot dipped gavalume steel sheet

The corrosion resistance is 2 to 5 times of hot dipped galvanized sheet. Continuous or intermittent use at temperatures up to 490°C does not severely oxidize or generate scale. The ability to reflect heat and light is twice of hot dipped galvanized steel. The reflectance of more than 0.75. It is an ideal building material for energy saving.

3. Electro-galvanized steel sheet

Since the zinc layer of the electro-galvanized sheet is thin, the zinc content is usually 20/20g/m2. So this product is not suitable for use in outdoor production of walls, roofs, etc. However, due to its beautiful appearance and excellent processing performance, it can be mainly used for home appliances, audio, steel furniture, interior decoration, etc.


Coating structure

2/1: Apply twice to the top surface, once to the back surface, and bake them twice.

2/1M: Apply two times on the top surface and back surface, and bake them once.

2/2: The top and back surfaces are painted twice and baked twice.

Use of different coating structures:

2/1: Poor corrosion resistance of single-layer backside paint, poor scratch resistance, but good adhesion. It is mainly used for sandwich panels;

2/1M: Better corrosion resistance of backside paint, better scratch resistance and processability, good adhesion. It is suitable for single-layer press plates and sandwich panels.

2/2: Good corrosion resistance, scratch resistance and processability. It is mostly for corrugated sheets. But it is not suitable for sandwich panels because of poor adhesion.


Organic coatings type

Polyester (PE)

Good adhesion, plenty of colors, wide range of moldability and outdoor durability, medium chemical resistance, low cost.

Silicon modified polyester (SMP)

Good hardness of the coating, wear resistance and heat resistance, as well as good external durability and anti-powdering, gloss retention. The flexibility is normal, and the cost is medium.

High durable Polyster(HDP)

Excellent color retention and UV resistance, excellent outdoor durability and resistance to chalking, good film adhesion, rich colors, and excellent price/performance ratio.

Polyvinylidene fluoride (PVDF)

excellent color retention and UV resistance, excellent outdoor durability and resistance to chalking, excellent solvent resistance, good formability and dirt resistance. But less colors and high cost.