Dynamic Surface Tension Measurement in Liquid Curtain Coating Systems
Dynamic surface tension at millisecond surface ages dictates liquid curtain stability and dynamic wetting limits in paperboard coating operations.
Slot Die Extrusion
Precision Application
Manufacturing techniques that force a coating fluid through a calibrated opening provide high uniformity across a wide web. In slot die extrusion, the liquid is pumped into an internal manifold that distributes the flow evenly to a narrow slot. This allows for the deposition of very thin and consistent layers of adhesives or barriers onto paper and film.
Gap Regulation
The distance between the die lips and the moving substrate is a variable that determines the thickness and stability of the liquid film. Micro-adjustments to the die geometry allow operators to compensate for variations in the viscosity of the coating or the speed of the machine. This level of control is necessary for applying expensive functional materials where waste must be minimized.
The system remains closed to the atmosphere, which prevents the evaporation of solvents and the contamination of the coating.
Operational Tolerance
High-speed production runs depend on the ability of the die to maintain a steady flow without clogging or leaking. Precision machining of the die internal surfaces is required to ensure that the pressure remains constant across the entire width of the slot. This prevents the formation of heavy edges or thin spots in the center of the web.
Slot die technology is a standard choice for modern high-performance coating lines.