1. Quality issues of the coating liquid itself
1. The coating contains too many volatile substances, which can easily evaporate into gas, causing bubbles during the coating process. Solution: Reduce the volatility of the paint, or increase the drying time.
2. If the coating viscosity is too large or too small, bubbles may easily occur. It is recommended to adjust the coating viscosity according to different coating materials. At the same time, the coating should be thoroughly stirred evenly before coating to avoid bubbles.
3. Excessive suspended particles in the coating will cause air to adhere between the particles and the surface medium, which will also cause bubbles. Solution: Filter or separate the coating containing excessive particles through sieves, centrifugation, etc.
2. Coating equipment and process issues
1. The bad condition of coating machinery and equipment, such as scraper wear, dents, insufficient flatness, etc., will produce bubbles. Solution: Maintain coating equipment in a timely manner and keep the equipment in good condition to better control the quality of the coating.
2. When coating, excessive humidity on the roller surface will produce bubbles. Solution: Use a degassing roller to accelerate the flow of the coating surface and prevent air from adhering to the coating surface.
3. Substrate issues
1. The presence of oil, water film or other stains on the surface of the substrate will affect the adhesion of the coating and easily lead to the generation of bubbles. Solution: Before coating, the surface of the substrate should be thoroughly cleaned and treated to keep it dry and clean.
2. The presence of dust, foreign matter and other impurities on the surface of the substrate will also produce bubbles during the coating process. Solution: Before coating, thoroughly remove impurities and foreign matter to maintain the smoothness and flatness of the substrate surface.
In short, there are various reasons for bubbles in coating, and corresponding solutions need to be taken according to the specific situation. During the coating process, it is necessary to ensure the quality and smoothness of the coating and try to avoid air bubbles that may affect the effectiveness of the ink and coating.
