Residual Volume of Entrained Air in Wound Roll

In the roll-to-roll printing process, air entrainment is an important factor affecting the quality of wound roll when the winding speed is high and the air permeability of the film is poor. In the winding process, a spiral air layer is formed in wound roll. At the same time, air leakage will occur with the increase of radial stress. The residual air inside the web will affect the magnitude and distribution of the stress. Therefore, it is important to study air residual volume. In this study, we get the air layer thickness equation from the relevant theory of air leakage. Secondly, incremental equation of the radial stress in wound roll is derived. Finally, the increment of the internal stress for each layer is substituted into the air layer thickness expression to obtain the air layer thickness which is the air residual volume. This study predicts the distribution of entrained air in the wound roll, which can be used to improve the analysis of the effect of entrained air on the internal mechanical properties of the wound roll.