The Effects of Adhesive Properties on the Removal of Pressure Sensitive Adhesive Contaminants by Pressure Screens

摘要

Pressure sensitive adhesive (PSA) materials have a significant negative impact on paper recycling.PSA materials are hard to remove in recycling,deposit on equipment,and are retained in the product,severely hampering operations.This research had as an objective to evaluate if PSA properties could be predictors of the removal of PSA materials with pressure screens in paper recycling.A review of some major research activities in this area is included.In this research,several different PSA materials were applied to paper,pulped,and characterized for particle size.Particles of the PSA were then subjected to a pressurized single slot screening experiment.The PSA material properties namely,glass transition temperature,contact angle,yield strain,yield stress,and modulus were determined.Statistical modeling determined that the particle size after pulping was not significantly related to any individual PSA property.The model further determined that particle passage in a pressurized screen was negatively related to both yield stress and particle dimensions.A commercial hot melt PSA adhesive had a very different screenability than did acrylate based adhesives.The hot melt adhesive was found to fold upon itself into a more spherical shape and to also contain more attached fibers,in agreement with a higher tack for this adhesive than acrylate adhesives.The passage of the PSA adhesive particles could be modeled with moderate accuracy using a simple extrusion model.These findings indicate that particle size and the yield stress are critical to the design of PS A materials that will not extrude through a pressurized screen.