Environmentally Benign Pressure Sensitive Adhesive (PSA) for Postage Applications: Development of the Laboratory Recycling Protocol, 1998 Recycling Symposium Proceedings

Since 1994, Springbom Testing and Research (STR) has been working with the United States Postal Service (USPS) to develop pressure sensitive adhesives (PSA) for postage stamp applications that do not adversely affect the environment. To take advantage of the recyclable adhesive developments in progress, the USPS sponsored a conference in 1995 during which the adhesive industry was invited to participate in the USPS Environmentally Benign Pressure Sensitive Adhesives for Postage Stamp Applications program. Thirteen companies participated in the program by submitting adhesive samples. To determine whether an adhesive was recyclable, a recycling protocol needed to be developed. The result of this development work has led to three-tier evaluation process with the development of laboratory, pilot scale, and mill scale recycling protocols. The laboratory and pilot scale protocols are being developed and implemented at STR and Forest Products Laboratories (FPL), respectively for the USPS. Both the laboratory and pilot scale protocols will be incorporated into a new USPS recyclable PSA stamp specification. All adhesive samples participating in the program that successfully meet all of the qualification requirements of the specification, including the newly developed recycling protocols, will be placed on the USPS qualified PSA stamp products list.

This paper discusses the development of the laboratory protocol and provides insight to the design and selection of parameters and methods used which define the current protocols. Also included in this paper are results of efforts to better understand the variables that affected the final outcome of the pulping trial, including temperature, adhesive level, and release liner. The next set of experiments investigated the variation in the image analysis measurement system used to evaluate the hand sheets made from the pulp accepts before and after screening.