Approaches Based on Strength of Materials for Adhesion Strength Considering Thickness of PSA Layer and Backing

Abstract

Adhesion strength of PSA tapes is usually evaluated by the peel test, but it is still unclear how it is affected by thickness of the PSA layer and the backing substrate. One effective approach is to focus PSA layer on the release process from the initiation of the deformation to separation of the elongated fibrils because the measured peel force is the resultant of release forces distributed along the curved backing substrate. It has been known that the maximum release force is located at the early stage of the release process, followed by the sharp decrease and plateau until complete separation. It is interesting to note that this transition of release force in the peel test is very similar to force curve measured by the probe tack test. In other words, the maximum release force on release process by the peel test could be directly measured the by probe tack test. Therefore, it is necessary to establish the relationship between these forces for generalized quantitative definition of the adhesion strength. This review introduces the resultant release force and the local maximum release force individually evaluated by the peel test and probe tack test with consideration of the thickness of PSA layer and backing substrate.