Dynamic surface tension measurement of water-based coating colour for Curtain Coater.
Whether the Curtain Coating method can achieve better results than other methods basically depends on physical and chemical characteristics of the used coating colours. Therefore, different factors such as the surface tension have an influence on the quality of the coating colour leading to instable conditions (tea pot effect) or parabolic paths in the curtain.
The wetting quality also depends on the surface tension. In order to adapt the surface tension to particular conditions and dynamic loads, additives are added to the coating colour. Regarding the coating colours formulation the main focus is on measuring the dynamic surface tension in order to draw conclusions about the wetting and flowout behaviour of the coating colours. Static measurement methods such as the ring- and plate method are not suitable for these analyses.
Tensiometer of SITA Messtechnik GmbH are based on the bubble pressure method; which allows for measurements of the surface tension from a highly dynamic until a quasistatic range.