The Effect of Pressure-Sensitive Adhesive Properties on Screenability

Pressure-sensitive adhesives (PSAs) are the major source of stickies in paper recycling. It is desirable that the PSA not break down into very small pieces during repulping so that it can be screened out. However, it is not clear in the literature what mechanical properties of PSAs are required to make PSAs screenable. In this study, the screenability of a range of PSAs was evaluated. The hydrophobicity, peel, shear, tack and viscoelastic properties, tensile strength, and contact angle of these PSAs were measured. High tack and peel strength generally increase the screenability of PSAs. The dynamic property of the PSAs also has an effect on screenability. A PSA with a higher stretch index has higher screenability. It is also necessary for a screenable PSA to have a certain degree of hydrophobicity. The optimized PSA properties for a screenable PSA in laboratory repulping settings are reported.