Innovative Approach to Solving "Stickies" Problem and Developing Environmentally Benign Pressure Sensitive Adhesives Through Partnerships, 1999 Environmental Conference Proceedings

Said AbuBakr

USDA Forest Service

Forest Products Laboratory

Joe Peng

U.S. Postal Service

As a result of a United States Postal Service (USPS) initiative, a work team consisting of the USPS, the Forest Products Laboratory (FPL), Springborn Testing and Research (STR), and industry representatives was formed. The industry representatives include papermakers, paper recyclers, paper collectors, equipment manufacturers, paper users, and adhesive and chemical suppliers. The objective of the work team is to develop new and innovative solutions to the problems associated with recycling recovered paper containing pressure-sensitive adhesives (PSAs). Initial open discussions were held at USPS-sponsored conferences during 1995–1997, followed by work team meetings, also organized by the USPS. As a result of this collaboration and based on the criteria set by the paper industry, the adhesive industry is formulating new PSAs that are mostly removable in the screening stage of the recycling process. As a result of these combined efforts, protocols were developed to evaluate the newly developed adhesives. This paper outlines a pilot-scale separation sequence to assess the removal of contaminants from the feed stock containing PSAs. The sequence involves high consistency pulping, pressure screening, forward and reverse cleaning, and washing and flotation deinking. The protocols simulating typical recycling operations and using preconsumed, postconsumed, and control stocks were further refined to reflect optimum operating conditions, such as temperature, consistency, screen size, and repulping energy. Fourteen newly formulated adhesives were evaluated using this pilot-scale protocol.