Controlling adhesive behavior during recycling

Adhesives can be formulated to facilitate their removal by typical paper recycling unit operations. The investigations described in this paper are focused on determining fundamental properties that control particle size during pulping. While pressure-sensitive adhesives (PSAs) with high elastic moduli tend to survive pulping with larger particles, facestock and adhesive surface properties also play critical roles. We investigated both the effect of wet-strength additives and sizing agents on screen removal efficiency and found that one can shift a recycling-benign adhesive to one that will probably cause a problem in a mill just by changing the facestock properties. A conclusion from this work is that all the components of a PSA label, laminate, facestock, primers, and adhesive, play a role in determining the behavior of adhesives during pulping and screening.