TENSION ASCENSION KNIFE COATING METHOD

摘要

To knife-coat elastic liquids without the presence of flow instability, the extension rate in the upstream region of the coating bead is kept low by increasing the distance over which the liquid must accelerate. The onset of the flow instability is delayed by insuring that the upstream liquid-air interface of the coating bead is relatively long and flat. This is accomplished by allowing the elastic liquid to pull itself over a relatively large distance out of a trough and into the knifing passage. The liquid is able to ascend into the knifing passage by virtue of liquid tension developed by the extensional flow in the upstream region of the coating bead.