The development of micro-gravure roll coating technology is based on the improvement of market demand for thin coating uniformity. This new coating method has simple mechanism, good repeatability and high reliability.
Let’s talk about the micro-gravure roll from 3 points as below:
Ⅰ Coating methods
Micro-gravure coating adopts kiss coating method, while ordinary gravure coating basically has a back roller. The function of the back roller is to make the substrate and the gravure roller better contact, so that the coating liquid can be transferred more.
However, due to the pressure generated by the back roller, when the pressure is improper, the substrate is prone to wrinkles and other problems, resulting in uneven coating. With kiss-coated microgravure coating, some potential problems are gone.
- The influence of positive coating and reverse coating on coating effect
- In the case of forward coating, part of the liquid is coated on the substrate, and part of the liquid is left on the roller, the liquid is split, and wire drawing and small droplets are generated in the middle, and the coating surface becomes uneven.
In reverse coating, due to the different movement directions of the roller and the substrate, shearing force will be generated, no wire drawing and small droplets will be produced, and the surface will be more uniform.
Ⅱ Application of Micro-gravure Roll
1) Lithium battery separator and pole piece coating: In the early days, φ50mm micro-gravure rollers were mainly used. Currently, φ80-100mm micro-gravure rollers are commonly used, and the lithium battery separator coating industry has a 70% share.
2) Release film: Release film, especially optical grade release film, mainly uses φ50mm micro-concave roller.
3) Optical film: Optical film covers a wide range, and there are many cases of application of micro-gravure rolls. At present, the mainstream use of Korean chrome-plated micro-gravure rolls and Murata ceramic micro-gravure rolls.
Ⅲ. The influence of coating and substrate on coating amount
The effect of speed ratio on coating amount: speed ratio is the biggest factor affecting coating amount. As the speed ratio increases, the coating thickness also gradually increases. When the speed ratio is approximately 2, it reaches the maximum value, and then decreases as the speed ratio increases. In the stage of speed ratio 0.6~1, the coating thickness rises relatively quickly, but in the field, the coating has problems such as streaks.
The above is an introduction to the micro-gravure roller knowledge, I hope it can help everyone understand, so that everyone will use the micro-gravure roller to operate more efficiently.