On the role of atomic ash in automotive paint

On the role of atomic ash in automotive paint

on the role of atomic ash in automotive paint

June 4, 2019

after 20 years of development in mini convertibles, China's automotive industry has used mold stamping for most of the skins of China's buses and buses, greatly improving the flatness of the car body, greatly reducing the amount of atomic ash, only using atomic ash locally to fill and level, and most of the car body is sprayed with medium coat on the primer, However, where atomic ash is not applied, the adhesion between the intermediate coating and the primer of the meter 3 carbon nanotube is poor. The adhesion of the parts with putty is very good, and the adhesion is also very good when the car is full of putty. In view of the new problems, we have carried out the following discussion and put forward solutions to the problems

1. Effect of atomic ash on coating adhesion

11 kinds of atomic ashes of different brands (including atomic ashes made in Japan and Germany) were used for experiments, and the baked electrophoretic primer plate (150mm × 70mm × 1mm) wipe the surface with clean dry gauze (do not polish the paint), apply half of it with atomic ash, put it into an oven with a constant temperature of 140 ℃ for 30min after 20min from the application of atomic ash, and take out the paint. Place it at room temperature for 60min, then polish the surface of atomic ash with 320 × water sandpaper (do not polish the surface of electrophoretic primer not coated with atomic ash), and make the formed atomic ash dust slurry flow to the surface of electrophoretic primer not coated with atomic ash. Dry the sample at room temperature, and then wipe the dust on the surface of the sample with clean dry gauze. After painting the surface of the sample, put it into an oven with a constant temperature of 140 ℃ and bake it for 30min. Take out the sample and place it at room temperature for 60min. At the same time, paint the primer plate without atomic gray and bake it in an oven with a constant temperature of 140 ℃ for 30min. Take out the sample and place it at room temperature for 60min. Use a grid to detect the adhesion

experiments show that the adhesion of half of the midcoat without atomic ash is poor, and the adhesion of half of the midcoat with atomic ash is between 0 and 1

due to the addition of leveling agent, anti sedimentation agent, dispersant and other high boiling point additives in the water-based electrophoretic primer, these additives will float on the paint surface when baking at high temperature, and these additives may form a weak boundary layer with atomic ash dust, affecting the adhesion between the primer and the undercoat where atomic ash is not applied

2. Influence of different processes on adhesion

different drying processes and dust removal methods were used to investigate the adhesion between primer and intermediate coat. The results are shown in Table 1

atomic ash, whether self drying or drying, dry grinding or water grinding, as long as the electrophoretic primer is polished or the surface of the electrophoretic paint is wiped with diluent, and the dust after atomic ash grinding is completely removed, the annual average growth of 11.2% will not affect the adhesion between the intermediate coat and the primer, and the adhesion between the intermediate coat and the primer can reach grade 0 ~ 1. 3. Adjust the formula and process of atomic ash production to avoid primer grinding and solvent wiping process

in order to simplify the coating process and reduce construction pollution, through the improvement of atomic ash production technology, adopt the process of no grinding primer and no solvent wiping. Therefore, adjust the formula and process of atomic ash resin production, and conduct a large number of screening and blending of fillers

the upper half of the electrophoretic primer plate is coated with atomic ash, and the timing starts from the coating of the ash. After being placed at room temperature for 20min, put the sample into an oven with a constant temperature of 140 ℃ for 30min, take it out, and place it at room temperature for 60min, and then polish the surface of the atomic ash with 320 # water sandpaper, so that the formed atomic ash dust slurry flows to the surface of the electrophoretic primer without atomic ash. Dry at room temperature, and then wipe the dust off the surface. Spray coating on the surface of the template, and put it into a 140 ℃ oven for 30min. After the sample is placed at room temperature for 60min, the adhesion shall be tested with a scriber

the experiment found that the adhesion between the intermediate coat and the primer can be improved by adjusting the formula of atomic ash, so that the dust basically does not affect the adhesion; If the dust from the parent's resources is fully utilized, and the adhesion between the intermediate coat and the primer is not affected, that is, the adhesion between the intermediate coat and the primer reaches level 0 ~ 1, one or two common raw materials must be removed from the atomic ash

the situation of water grinding and painting of atomic ash after self drying is the same as that of water grinding and painting of atomic ash after high temperature baking, that is, the dust of atomic ash naturally curing and baking curing has the same effect on the adhesion of electrophoretic primer and primer

if the electrophoretic primer is polished or the surface of the electrophoretic paint is wiped with diluent, even if the commercial atomic ash is used, the dust after atomic ash polishing will not affect the adhesion between the intermediate coat and the primer, that is, the adhesion between the intermediate coat and the primer can still reach grade 0 ~ 1