The paint surface of a car is divided into four layers in the traditional painting process, which together play a protective and beautiful function on the car body. With the improvement of the process, the complex can reach seven or eight layers. Take the four layers of traditional craftsmanship, from the inside to the outside, they are electrophoresis, intermediate coating, colored paint, and varnish.
1. Electrophoresis layer (cathodic electrophoresis)
Put the pre-treated body-in-white in the electrophoretic paint with cations, apply a positive charge to the anode tube on the bottom of the electrophoresis tank and the wall panel, and apply a negative charge to the body, which will form a potential difference between the anode tube and the body , And the positively charged cationic electrophoretic paint will migrate to the white body under the action of the potential difference, and finally adsorb on the body to form a dense paint film. This paint film is called electrophoretic paint, and the electrophoretic paint is baked After oven drying, it becomes the electrophoretic layer.
The electrophoretic layer can be roughly regarded as the paint layer directly attached to the steel plate of the car body, so it is also called the primer. In fact, there is a phosphate layer formed in the pretreatment between the electrophoretic layer and the steel plate. The phosphate layer is very Very thin, only a few μm.
There are two main functions of the electrophoretic layer, one is to prevent rust, and the other is to improve the adhesion of the paint layer. The anti-rust ability of the electrophoretic layer is the most important and most critical of the four paint layers of car paint.
2. Medium coating.
The middle coat is a paint layer between the electrophoretic layer and the colored paint layer. The middle coat is sprayed by a robot.
Its function is relatively simple. It has anti-ultraviolet rays, protects the electrophoretic layer, improves the anti-rust ability, and takes into account the smoothness and impact resistance of the paint surface. Finally, it can also provide some adhesion for the colored paint layer. It can be seen that the middle coating is actually a lacquer layer that connects the top and the bottom, and plays a connecting role for the two functional coatings, the electrophoretic layer and the colored lacquer layer.
3. Color paint layer.
The color paint layer, as the name suggests, is a colored paint layer, which provides us with the most direct color perception, red or black, or kingfisher blue, or Pittsburgh gray, or cashmere silver, or supersonic quartz white. The quality of the paint spraying directly determines the expressiveness of the car body color, and the functionality is very important.
Color paint can be divided into three types according to different additives: plain paint, metallic paint and pearl paint.
(1) Plain paint is pure color. Red is just red, and white is just white. It is simple, without other hues, and without metallic sparkle, so it is called plain paint. Compared with metallic paint and pearl paint, plain paint has a lower cost and a more monotonous color. Even under different lighting conditions, it will not change much.
(2) Metallic paint is based on plain paint, with metal particles (aluminum powder) added to it. In the earliest car painting, only plain paint was used. Later, it was discovered that by adding ultra-fine aluminum powder into plain paint, the paint layer showed a metallic texture. In the light, the light is reflected by the aluminum powder and comes out through the paint film, as if the entire paint layer of the car is glowing, shimmering with metallic luster.
Metallic paint is currently the most widely used. Most dark colors are metallic paint, such as red, yellow, blue, green, purple, silver, and gray.
(3) Pearlescent paint. It can be understood that by replacing the aluminum powder in the metallic paint with mica or pearl powder (which is rarely used by manufacturers), the metallic paint becomes pearlescent paint. At present, pearl paint is mainly white, and it is also often called pearl white, pearl white. Under light, it is not pure white, but a pearl-like color. This is the mica itself is a sheet-like transparent crystal. When light enters the paint layer, very complicated refraction and interference will occur through the mica sheet, and the mica itself has some green, brown, yellow and pink tones. This makes the pearl paint on the basis of the main color, adding extremely rich pearl-like glitter. The same lacquer surface will have subtle changes from different angles, and the richness and rendering power of colors will be greatly increased, giving people a luxurious and noble feeling.
4. Varnish layer.
The clear paint layer is the outermost layer of the car paint, a transparent paint layer that we can touch directly with our fingertips. The function of varnish is mainly to improve the gloss of the paint surface, enhance the texture, prevent ultraviolet rays, and prevent slight scratches.
Although it is said that the original car paint has several layers, it is still relatively thin. If you worry about the paint problem later, you still need to do nano coating or car paint protection film.
Double layer nano coating, one set is enough
The lotus leaf is hydrophobic, antifouling and easy to clean
Sealed car paint, long-lasting brightening
——The case comes from China