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Application and analysis of water-based paint fillers in automobiles

Automotive coatings have always been one of the key supporting areas of the coating industry, and the strict quality control in the automotive coatings field has given rise to many construction methods such as cathodic electrophoresis and electrostatic spinning cups. Therefore, many industry insiders believe that the automotive coatings in the automotive coatings field represent the technical level and development trend of the national coating industry.

In recent years, with the continuous improvement and development of raw materials in China, automotive coatings have gradually expanded from sedan applications to commercial vehicles such as trucks, pickup trucks, motorcycles, and the light industry sector. At the same time, in order to meet environmental requirements and the high demand for commercial trucks in the market, the commercial truck market is gradually upgrading from solvent based to water-based and high solid separation products. In order to adapt to the production rhythm of the traditional solvent truck market, water-based products have developed a water-based 3C2B product process, with the intermediate coating still retaining the original drying process.

The intermediate paint not only firmly adheres to the surface of the electrophoretic primer coating, but also easily combines with the upper topcoat coating, giving the overall coating better resistance to stone impact and impact. It has filling properties and can effectively eliminate pits, patterns, and sandpaper marks caused by primers, putty, etc., so that after spraying topcoat and varnish, a smoother and fuller coating can be obtained, improving the freshness and fullness of the entire paint film. At the same time, it can effectively reduce the pulverization effect of ultraviolet radiation and other factors on the electrophoretic primer coating, optimize the overall weather resistance level of the coating, and extend the service life of the coating.

The function of coatings and primer layers in automobiles is different, and they do not need to bear the functions of rust prevention and corrosion prevention. The pigments and fillers are usually mainly titanium dioxide, carbon black, talc powder, and barium sulfate. Talcum powder has excellent dryness and grinding ability, and its excellent suspension and thickening properties can also form a synergistic anti settling effect with anti settling agents. However, its oil absorption value is high, its extinction is high, and there is a certain amount of addition limit. Barium sulfate has excellent acid and alkali resistance, and its low oil absorption value has minimal impact on the gloss of the coating. It can also play a certain synergistic anti UV effect, but its specific gravity is large and easy to precipitate, requiring the use of bentonite or other rheological additives together.

That is to say, when preparing the paint formula, talc powder and barium sulfate are usually used in combination, which can effectively combine the advantages of the two fillers, achieve acid and alkali resistance, improve surface dryness and polishing, and make up for their respective defects. At the same time, due to the presence of paint and varnish protection on the surface of the intermediate coating, some low-end customers can also choose to use a combination of natural barium and talcum powder.

The following is a common formula for water-based intermediate coating materials, which uses resin grinding technology to effectively coat pigments and fillers, and improve the stability and mechanical properties of the finished product. After dispersing and grinding the color paste raw materials to the specified fineness and filtration process, the main resin, amino resin, solvent, additives, etc. are added in sequence and dispersion process to form a complete water-based intermediate paint formula. Add a certain amount of water to dilute the product to the specified viscosity for spraying, and make the plate according to the baking process. After the baking is completed and cooled, spray the color paint and varnish as required and bake and cool to obtain the corresponding water-based 3C2B sample for automobiles.

Automotive water-based intermediate coating slurry
Number	Raw material	Number	Raw material
1	Deionized water	7	Anti settling agent
2	AMP-95	8	SD-2 organic bentonite
3	Grinding resin	9	MA-100 carbon black
4	BYK-011	10	Talc powder
5	Dispersing agent	11	Barium sulfate
6	Ethylene glycol butyl ether	12	LR-996 titanium dioxide