Saturation coating process is a technic consisting of immersing a porous substrate in a tank containing water or solvent based coatings, impregnating fibers throughout the entire web thickness. This technic is used to change properties of papers, nonwovens and textiles. There are a variety of arrangements available for this type of coaters, which can be configured as either pan fed or knife fed.
They can be selected for water based and solvent based coatings. The pan fed design will be preferred for lower viscosity coatings and equipped a certain number of rolls, for achieving the required dip dwell time. The design of these rollers, which can be driven or idling, is crucial for minimizing friction of light weight nonwovens and other low tensile strength substrates. Metering apparatus are typically located downstream of the dip tank, such as nip rollers or doctor blades.
The knife fed design, similar to dual-sided knife-over-roll coaters, will be ideal for coatings with higher viscosity, and equipped with rail mounted edge dams, for easily adjusting the coating width. It this configuration, coating is pre-metered between a knife and back-up roll, and subsequently squeezed into the substrate.
