Type of Coating
The coating types currently used for PPGI coil include PE, PVDF, SMP, acrylic, PVC, etc.
Polyester(PE)
The Polyester coating is easy to be processed and formed because of its good adhesion, and the price is relatively cheap. But the other degree of UV resistance and chalking resistance is relatively low. Polyester prepainted steel can be used for the roof of ordinary civil buildings.
SMP
SMP steel plate has better durability, and the cost is higher than the PE coating. Silicone is not as good as PE in terms of adhesion and processing formability to materials,
High durable Polyester (HDP)
It is better than ordinary SMP coatings, and its outdoor weather resistance reaches 16 years. Its flexibility and weather resistance are higher.
PVC
PVC coating has nice anti-chemical and anti-water, and the coasting is relatively thick, which can well protect the substrate.
The PVC coating is rarely used because they pollute the environment.
PVDF
PVDF coatings have great color retention and corrosion resistance. Among the PPGI sheet coating for construction, it is the highest grade.
Acrylic
The comprehensive performance is good, the price is expensive, and it is only used in specific fields (such as containers).
| Coating primer | Top paint coating | Service life(years) |
|---|---|---|
| 1) Epoxy primer, good adhesion, water resistance, alkali resistance, chemical corrosion resistance, poor single toughness. 2) Polyester primer, good adhesion, good flexibility, sensitive to humid environment, chemical resistance is not as good as epoxy primer. 3) Acrylic primer, good adhesion, good toughness and high pretreatment requirements. 4) polyurethane primer, chemical resistance, abrasion resistance, durability, toughness | 1) Polyester resin, good adhesion, molding and outdoor durability. | 8-10 |
| 2) Silicon Modified Polyester (SMP) | 10-15 | |
| 3) High weather resistant polyester (HDP) | 12-15 | |
| 4) Polyvinyl fluoride (PVC) | 12-15 | |
| 5) Polyvinylidene fluoride/fluorocarbon (PVDF) It has good formability and color retention, good outdoor durability and powder resistance, solvent resistance, limited color and high price. | 12-20 |
Coating Performance Comparison Table
| Category | Hardness | Bend | Corrosion resistance | Weather resistance | Cost | Coating thickness requirements /um |
|---|---|---|---|---|---|---|
| Polyester | excellent | good | good | good | excellent | 20 |
| Acrylic | excellent | general | good | good | inferior | 20 |
| Silicon modified polyester | good | general | good | excellent | good | 20 |
| PVC sol | general | excellent | excellent | good | inferior | 200 |
| PVDF | general | excellent | excellent | excellent | inferior | 25 |
| HDP | good | excellent | good | excellent | good | 20 |
You need to consider when choosing a primer
1) Adhesion of primer and finish coating
2) Corrosion resistance of primer
For the back coating, if the color-coated steel sheet is a Single layer, Color coated steel with a back primer plus a back finish coating was selected.
The primer is of the same variety as the front, and a layer of light color (such as white) polyester is selected for the finish coating.
If the PPGI steel coil is used as a sandwich panel, a layer of epoxy resin with excellent adhesion and corrosion resistance is sufficient.
