Other key points in waterborne coating construction
We all know that there are many factors affecting the spray effect during the construction of water-based paint. In addition to the effects of temperature and humidity mentioned above, it also includes the degree of drying of water-based epoxy primer, leveling flash time, water-based Paint spraying equipment, water-based topcoat repairing process, etc. Next, I will introduce you to other key points in the construction of waterborne coatings!
1. Monitoring of the dryness of waterborne epoxy primer and its effect on the compatibility with atomic ash
Due to the slow evaporation rate of water, the early drying speed of the aqueous two-component epoxy primer is slow. When the dryness of the paint film is insufficient, the bottoming phenomenon of the putty is prone to occur, the primer is softened, and the adhesion is even lost. Therefore, under the premise of selecting the type of water-based paint, it is necessary to pay attention to the degree of drying of the primer before the primer is applied to the primer during the construction process. If the dryness requirement is not met, it is necessary to extend the drying time or increase the baking.
2. Control of flow-level flashing time during construction of water-based topcoat
In the case of baking conditions, unlike the aqueous primer and the aqueous intermediate coating, the aqueous two-component topcoat has a longer flash-drying time after spraying than the solvent-based coating, and is generally controlled at 60 min or more. Only when the moisture in the wet film is fully released and then baked can avoid pinholes and blistering during the baking process. Turning on the ventilator during leveling and flashing can accelerate the release of moisture from the wet film and shorten the flashing time to 30-60 minutes.
3. Requirements for tools and equipment in the process of water-based paint spraying
Since the water-based paint solvent is deionized water, the inside of the ordinary spray tool is mostly carbon steel. After a long time, the internal parts will be corroded, and rust and other contaminants will be generated. Once again, the spray will easily form defects such as particles and shrinkage holes. It is easy to cause the gun to be blocked, and the parts of the spray gun are replaced frequently and the cost is high. Therefore, the water-based paint spraying tool must be made of stainless steel. During the test, our company uses SATA water-based paint spraying tools on site, and the appearance of the spray is good.
In addition, water-based paints have higher environmental requirements than solvent-based ones. Existing paint houses are difficult to meet their spraying requirements, especially in southern China. Therefore, paint houses must be equipped with constant temperature and humidity units to ensure film quality during spring construction.
4. Control of water-based topcoat repair process
After the topcoat is applied, in the process of process flow, transportation and operation, the paint film is inevitable, so the water-based paint construction process also needs a perfect topcoat repair process. The water-based topcoat is in accordance with the solvent type after repair. After the paint repair process is applied to the new paint, a layer of light-loss interface is easily formed on the edge of the new and old paint film, and it is difficult to completely solve the problem through the interface water. Existing solutions include:
(1.) Select a special interface water with good matching;
(2.) If the problem can still be solved by using the interface water, it is necessary to dry the repaired area after the new paint film is dried, and polish the polished part with the coarse polishing wax + wool pad, and finally use the fine polishing wax + wool pad. Fine polishing.
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