Causes and Solutions of Spreader Stripes

When the primer is coated with a metering rod. When the top coat is coated with a scraper, it is generally not easy to produce streaks, but. When both the primer and the surface are coated with a scraper, it is easy to produce streaks. The stress on the paper web during the metering rod coating process is shown in Figure 1. When the paper web enters the coater, the stress gradually increases, and as the paper web exits the coater, the stress begins to decrease until it reaches zero. Therefore, in this process, the coating first forms a smooth film on the surface of the paper web, and then. With the gradual reduction of the stress, the formed film fork is gradually destroyed, making the paper surface rough. Fig. 2 is a stress diagram during knife coating. It can be seen from the figure. Blade coating is when the web leaves the coater at the time of maximum stress. Therefore, knife coating can obtain a smooth coating surface. This is why blade coating produces better quality paper than meter bar coated paper. However, according to the coating theory. The high smoothness of the coating after the primer is not conducive to the coating of the surface layer. It makes it difficult for the top coat to adhere to the paper, so it is easy to streak when the top coat is applied.