The key process control of coating production
1. Measurement of coating thickness
The coating thickness that can be measured online refers to the wet coating thickness, that is, the thickness of the coating liquid before drying. The coating thickness is directly related to the quality of the coating, such as the digester coating film, the coating thickness is too low will reduce the binding force with the aluminum layer, resulting in reduced digester resistance after making bags. Coating thickness = coating liquid consumption/coating area = coating consumption at fixed time/coating width × coating length (TDO speed × measuring time)
2. Adjustment of coating thickness
By adjusting the position of the rubber roll above the concave roll, the coating Angle on the concave roll can be adjusted, and the contact area between the concave roll and the cast sheet can be increased or decreased to achieve the purpose of adjusting the coating thickness. The coating thickness can also be adjusted by adjusting the roller speed. If the thickness of the coating gradually decreases under normal production conditions, it should be caused by the clogging of the coating roller, and it is necessary to stop the coating immediately, clean the coating system, clean the coating roller, and replace the coating roller if it still does not work.
3. Flatness of the coating solution
The coating solution needs to be evenly coated on the coating roller, in order to achieve this effect, it is necessary to carry out corona treatment on the cast sheet before coating to enhance the surface tension of the cast sheet, and it is necessary to add the appropriate proportion of wetting agent in the coating solution to enhance the leveling effect. However, increasing the wetting agent may cause bubbles and drying problems of the coating solution, and it needs to be added appropriately according to actual needs.
4. Storage time and storage conditions of coating solution
The coating solution requires sealed storage away from light, because part of the coating solution will deteriorate at high or low temperatures, and the temperature needs to be controlled during storage and transportation. The coating liquid needs to be used within the validity period, and the already prepared coating liquid needs to be stored in the dispensing tank with a cooling jacket, continuously stirred, and cannot be stored for too long.
5. Coating defect control
In coating film production, if part of the coating roller fails to transfer the coating liquid to the cast sheet, it will cause coating leakage. During the subsequent processing of the film,
