PLOTTING OF SELF-ADHESIVE FILMIC MATERIALS - AN INVESTIGATION INTO WHAT MAKES THE PERFECT PLOT

摘要

Successful plotting and stripping depends on a delicate balance of several properties where all parts of the laminate play a role. Plotting and weeding speeds should be in tune with plot-complexity and cut-accuracy. The root cause of the phenomenon of bad stripping behaviour lies in the always present bridges of adhesive that span the cut-gap after plotting. These defects will always be present and a successful plot material will have to have the robustness to deal with these bridges. The force needed to break the bridges so the stripping can be performed error-free depends on 4 factors: the number and size of these bridges; the stiffness of the facestock; the cohesion of the adhesive layer; and the bond-strength of the adhesive to the release-liner (i.e., the release-value). The release values must be high enough to allow destruction of these bridges while stripping. The release value of the adhesive to the specific silicone release liner has to lie in a specific window for the whole laminate to be successfully strippable. As the laminate is inevitably gradually changing over time, care must be taken that, during the acceptable storage time and conditions of the plotting material, the balance is not disturbed so much that the plotting and/or stripping will become problematic. For this, a window must be defined for each specific laminate, based on the stiffness and stiffness-change of the filmic over the acceptable storage time and conditions, the cohesion of the employed adhesive. A more cohesive adhesive requires a different window and the normal change in release values over time.