Color-coated steel plate is a composite material formed by coating one or more organic coatings on a metal substrate and baking. It is used in home appliances and the construction industry because of its good corrosion resistance and aesthetics. Since the establishment of the first color coating unit in the late 1980s, after 30 years, the number of products produced has increased from 16 colors in the first four coating categories to more than a dozen involving industries and uses such as construction and home appliances. Coating types. Color coated board coatings often encounter some technical problems in use. This article briefly introduces several common problems.

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Flash paint visual error problem

Color-coated board coating topcoats are divided into two categories: “plain paint” and “flash paint” (flash paint is divided into “metal paint” and “pearl paint”). Unlike plain paint, which produces color through the selective absorption and diffuse reflection of light by pigment particles, metal and pearlescent pigments are layered and arranged in the same orientation in parallel to the paint film. When the light hits the surface of the paint film, part of the light Due to the direct reflection of the aluminum powder, there is almost no absorption. Part of the light is particularly bright and gives a very dazzling feeling. Part of the light is reflected by the aluminum powder multiple times, and the light is dark. Therefore, it gives different visual effects when viewed from different angles.

The light generated by the same incident light source increases with the number of reflections, and the light becomes darker. The effect seen at the viewing angle A and the viewing angle B will vary depending on the light. Therefore, the visual effect of the flash paint will depend on the light incident angle (corresponding to Dawn changes in nature, etc.) and observers’ observation positions vary. Therefore, the color difference of flash paint is more difficult to control, and the user sometimes reflects the phenomenon of visual color difference in use.

In steel paint coating management, on the one hand, the same user contract should be selected as much as possible in the production control of the same user contract, and the same batch of paint is produced at the same time to avoid color differences caused by differences in different paints and processes. A multi-angle color difference meter that is closer to the measurement effect of the human eye is used for color difference comparison. On the other hand, it guides the user to help them avoid the problem of color difference caused by different material installation directions.

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Coating adhesion issues

When color coated board is used as a sandwich board, a problem often faced is poor adhesion or foaming. Because when the coating is used to make sandwich panels, the coating must be effectively combined with the foaming agent to ensure the integrity of the sandwich panel. Generally speaking, the problem of bad adhesion encountered by users is “not sticking”.

Not sticking

The back coating of the color-coated board is poorly bonded. The reasons for this problem are mainly as follows:
(1) Glue reaction time: The length of the glue reaction time during processing will affect the foaming effect, and the foaming effect will not be too ideal if the time is too long or too short.

(2) Coating quality: The type of coating determines the surface activity of the coating after curing, which will affect the foaming effect of the color coated board and the foaming agent. If the coating has less reactive groups, the foaming properties will be affected. It is a poor foaming model for coatings with less reactive groups.

(3) Glue quality: Glue for foaming is generally composed of black glue and white glue. White glue is a polyether polyol with hydroxyl group and black glue is a product with cyanate ester. The two are mixed at a certain ratio to form polyurethane , That is, foam material. The active ingredients in the glue seriously affect the foaming effect of the product. If you add other materials to the white glue to reduce costs or replace the polyether polyol with a lower-priced polyester polyol, it will most likely cause poor foaming.

(4) Others: Foaming process and production environment are also important factors affecting the quality of the finished sandwich panel.

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