Recycling Behavior of Microsphere Adhesives, 2000 Recycling Symposium Proceedings

Fred Gustafson, Paul Resler--Microsphere adhesives are small, crosslinked adhesive particles used in many repositionable adhesive products. The adhesive resembles toner powder in size and surface chemistry. Like toner, flotation is the most effective method of removing the adhesive in the deinking process. A model system for understanding the removal of microsphere adhesives is the repositionable note. Laboratory and pilot-scale repulpability trials were conducted on Post-it® Notes according to USPS protocols. Research included pulping, screening, centrifugal cleaning, flotation, washing, image analysis, and retention studies. Screening removed only the largest agglomerates of the adhesive. Flotation removed more than 90% of the adhesive. Residual adhesive in the final handsheets was 5-38 ppm. The residual adhesive is almost all retained in paper by retention aides. Very little adhesive was detected in wastewater during papermaking. Because the adhesive is so small, determination of microsphere adhesives requires higher resolution image analysis than the USPS image analysis protocol method.