There are four types of primer and film thickness primer: epoxy resin, polyester resin, acrylic resin and polyurethane resin. The primer is generally selected according to the bottom use of the product, the occasion of use, the degree of processing, and the matching of the top paint. The film thickness of the primer is usually 5um.

1. epoxy primer

It has good adhesion to the substrate, good water resistance, alkali resistance and chemical corrosion resistance, and is the earliest coil primer, and its flexibility is not as good as other primers.

2. polyester bottom

Good adhesion with the substrate, excellent flexibility, more sensitive to wet environment, chemical resistance is not as good as epoxy primer.

3. water-soluble acrylic primer

Good adhesion to the substrate, excellent flexibility, organic solvent content bottom, low temperature curing, not suitable for storage in a humid environment, high requirements for pretreatment.

4. polyurethane primer

It has chemical resistance, friction resistance, durability and good flexibility.

Type of finish and film thickness

The most commonly used topcoats are polyester, silicon modified polyester, polyvinyl chloride plastisol and polyvinylidene fluoride.

1) Polyester

Good adhesion, wide range of formability and outdoor durability, moderate chemical resistance.

2) silicon modified polyester

The hardness, wear resistance and heat resistance of the coating film are good, as well as good outdoor durability and non-powdering, gloss retention and flexibility are limited, and the cost is medium to high.

3) polyvinylidene chloride

With good formability and color retention, excellent outdoor durability and resistance to powder, solvent resistance, limited color, expensive.

4) polyvinyl chloride plastic sol

Excellent external durability and chemical resistance, damage resistance, beautiful, need special primer matching. The surface can have a smooth type for compression or automatic shrinkage type to form a pattern. The coating thickness is generally greater than 100um, in addition to plastisol, under normal circumstances, the coating thickness of the primer and top paint > =20um, the performance of its products can achieve the predetermined purpose.