Reverse Roll System

Function/Description

This system is called "Reverse Roll Coater" because the applicating roller moves in the opposite direction to the web´s moving direction. Principally, this system consists of three roller that are either arranged vertically align or in an S-shape. The coating raw material is placed between the two upper rollers and is kept in the roller gap by double-sided limitating knives.

The coating weight is determined by the distance between the upper metering roller and the application roller, but also by varying the roller´s speed. The lower roller that guides the material mostly is a rubber roller. The coating roller transmits the plastic film on it in counter direction onto the substrate. Each roller is powered separately. By default, the speed of each roller can be varied by approximately 50%. The rotating direction of the upper roller can also be adjusted to the counter direction.

Because of the various possible settings, the application can be defined optionally by the gap distance, the rotational speed of the rollers and the relative roller speed to each other. Also the thickness of the coating layer can be influenced by changing the relative speed of the rollers to each other and the relative speed between the applicating roller and the substrate. The Reverse-Roll-Coater is used for the processing of pastes with a low viscosity and a good flow behavior. Dilatant pastes, which means coating raw materials the viscosity of which increases proportionally to high shearing forces, as well as highly viscous pastes cannot be processed because of the high shearing forces that appear. However, very thin applications can be realised with this technology.

Examples