Investigation of creasing-induced surface damage in dispersion-coated paperboard in relation to the number of creasing rules and their spacing

Abstract

Creasing is a converting step in paperboard packaging development in which controlled compression is used to define a series of folds. This type of deformation can cause damage to the surface of coated paperboard, affecting its barrier performance. This thesis investigates how the number of creasing rules and spacing between creasing rules affect surface damage and barrier properties in dispersion-coated paperboard. Laboratory-scale creasing experiments were conducted using single-rule and three-rule flatbed-type tools with varying spacing between the three creasing rules at two nominal crease depths in both machine and crossmachine directions. The achieved crease depths were verified using optical profilometry, and the barrier performance was evaluated using oil and grease resistance measurements. The results show that creasing with three rules leads to earlier oil penetration compared to creasing with single rule, particularly when the distance between adjacent rules is shorter. Closely spaced three-rule configurations resulted in the lowest OGR, whereas increased spacing between the three rules improved barrier performance and approached the behavior of the single-rule configuration. The results indicate that both the number of creasing rules and the spacing between adjacent rules are governing parameters influencing creasing-induced barrier degradation in dispersion-coated paperboard.