Stickies

Though the word is used to cover a variety of problems, most usually stickies are understood to involve adhesive materials coming from the reuse of waste paper pulp.

The main culprit in many problems with stickies is the polyvinylacetate (PVA) and other binders in the "pressure-sensitive" labels that have become so common in mail and throughout our society over the past couple of decades. The problem with stickies is that they cling together and tend to build up into globs or strings. They can adhere to papermaking equipment, they can fill felts, and they can make spots in the product. Because they are deformable, they cannot be completely excluded by pressure screens.

The best ways to deal with stickies include avoiding them (by selecting the kind of pulp source), removing them during deinking of the wastepaper (easier said than done), or adding enough talc to the system to overcome their tackiness. It is sometimes difficult to remove stickies by screening due to their ability to deform and become extruded through very small holes. Also, high levels of shearing action during processing of wastepaper can result in micro-stickies that are not easily retained.

Recently there has been a lot of work to understand the nature of stickies and develop more effective control strategies. For further information the following articles are recommended as a starting point.

Some further ideas can be found in two essays that are titled "A Cure for Stickies?" and "Pitch and Stickies - a Chemist's View."

References

Doshi, M. R., "Properties and Control of Stickies," Prog. Paper Recycling 1 (1): 54 (1991).

Douek, M., Guo, X.-Y., and Ing, J., "An Overview of the Chemical Nature of Deposits/Stickies in Mills Using Recycled Fiber," Proc. TAPPI 1997 Recycling Symp., 313 (1997).

Fogarty, T. J., "Cost-Effective, Common Sense Approach to Stickies Control," Tappi J. 76 (3): 161 (1993).

Venditti, R. A., Chang, H. M., and Jameel, H., "Overview of Stickies Research at North Carolina State University," PaperAge 1999 (11): 18 (1999).

Wilhelm, D., K., Makis, S. P., and Banerjee, S., "Signature of Recalcitrant Stickies in Recycled Newsprint Mills," TAPPI J. 8 (12): 63 (1999).

PLEASE NOTE: The information in this Guide is provided as a public service by Dr. Martin A. Hubbe of the Department of Wood and Paper Science at North Carolina State University (m_hubbe@ncsu.edu). Users of the information contained on these pages assume complete responsibility to make sure that their practices are safe and do not infringe upon an existing patent. There has been no attempt here to give full safety instructions or to make note of all relevant patents governing the use of additives. Please send corrections if you find errors or points that need better clarification. Go to top of this page.


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