Second-Generation Repulpable PSAs for Benign USPS Postage Stamps
While the new self-adhesive design enables the convenience of a peelable, 'no lick' stamp, conventional PSAs have been identified as troublesome contaminants within the paper-fiber recycling industry. When present in the recovered paper stream, the PSA materials have an adverse impact on the recycling process and products. Insufficient removal of PSAs in paper-recycling mills contributes to poor paper quality, reduced production efficiencies and ineffective recycling of post-consumer waste.
During the paper recycling process, PSA material in the feed tends to form globs, referred to as "stickies" by the industry, creating serious difficulties for paper recyclers.1 In the recycling process, various techniques are used to remove the stickies and other contaminants from the pulp. Stickies that survive the recycling process reappear as dirt and irregularities in the finished paper that are unacceptable, especially in the finer grades of printing paper.