Paint for color coated steel plates

There are also many examples of hot-dip galvanized steel plates used in structural materials, ventilation channels, and purchase materials for various machines and machinery without painting. However, it is generally necessary to paint the base material to protect it from corrosion or attach color. In order to make the steel corrosion prevention, to galvanize, in order to improve the efficacy, and then paint on the galvanized surface with paint, so that the galvanized surface is not directly in contact with the air. But it does not mean that the use of any paint can be painted, but must be suitable for the substrate shake, and according to the purpose of use, choose the appropriate paint and painting method, inappropriate painting will cause the film to break, peeling, uplift, and material rust and other problems, so please pay attention to the following matters.

1. Pretreatment

In order to make the coating and the galvanized surface fully tightly combined, it is necessary to chemically treat the galvanized surface first, or a similar treatment to cause the coating to easily adhere to the state.

Zinc is a metal with high surface activity. If it reacts with the resin in the coating for a long time, the adhesion of the coating film will be deteriorated, so the surface of zinc needs to be blunted. If it is painted with sweat, fingerprints or oil, it will cause defects after painting. Therefore, when preprocessing, pay attention to the following points.

(1) Formation treatment method

a. In order to completely remove surface stains, attachments, oil, etc., please use appropriate methods for degreasing.

b. Formation treatment, there are generally two kinds of chromic acid and phosphate film, please choose according to the use. Generally speaking, phosphate film is superior in tight adhesion and corrosion resistance of the coating film. But chromic acid is better in formability.

c. After the formation treatment, to be fully dried, please paint in a state without moisture.

(2) Paint pretreatment method

When it is not possible to use the formation process, as a pretreatment method, please apply phosphoric acid primer. Even if it is only applied once, it can obtain the same effect as the formation treatment, and obtain a strong coating film. As a base paint, it has good intermediate adhesion with various topcoats, so it is recommended.

2. the choice of paint

When the galvanized steel plate is painted, the expected performance should be different if the purpose is different. According to the performance of the paint, its quality can not be universal, can only be evaluated on the basis of the quality of more attention to the characteristics of the paint design. As a benchmark for evaluation, special requirements :(1) corrosion resistance (2) weather resistance (3) workability (4) surface hardness (5) pollution resistance, etc., must be used to meet the requirements of the paint.

3. Repair of coating film

For building materials that are exposed to the outdoor atmosphere, please accurately determine the repainting period before repainting. When the zinc disappears from the substrate, it rusts. It's too late to repaint after it's rusted. If most of the surface of the board that has been painted is covered by white powder (powdery phenomenon), it is the appropriate time to repaint. It is repainted to work best during a dry period with little moisture.