Characteristics Of Stickies In The Process Of Pulping And Papermaking With Recycled Fiber

With the adjustment of raw material structure in paper industry, Recycled Fibers have been paid more and more attention. During application of recycled fibers, plenty of contaminants such as pressure-sensitive adhesive, hot melt adhesive, coating adhesive, ink binding adhesive from waste paper as well as the lipophilic wood resins are greatly released and dispersed in the pulp suspension. These contaminants could form the deposits on the wire, press section and dryers or the surface of paper sheets and would be harmful to the runnability of paper machine and product quality. After stickies entering the recycling system of waste paper, there would be a diversity in its size, shape and stickness etc. this would result in more and more serious problems for waste paper recycling.Based on this, deposit obtained from a paper mill was analyzed and its basic origin was confirmed. Some substances were chosen as the model substances to study the factors which influence the stickies deposit. Based on the analysis and statistics of stickies problems in part of paper mills in Asia-pacific region, it is found that paper defect, inorganic and organic deposits were ranked top three for the problems which resulted from stickies deposit.Firstly, according to the analysis of the deposit from the dyer section in Liner Mill, it is found that Poly (2-ethylhexyl acrylate)and Ethylene-vynl acetate(EVA)were taken as the source of stickies, but their content in deposit was only less than 1/10. Most of the substances in deposit were calcium carbonate and fines which all were nonsticky.Secondary, PSA (Press Sensitive Adhesive) and Tall oil were respectively chosen as the model substances of the wood resin and the synthetic adhesives to study the factors influencing the pitch and stickies deposit. The results showed that there is a significant effect on the pitch/stickies deposit for cacium ions consistence. Same significant effect for fines in suspension, more pitch/calcium soaps particles could be absorbed by fines compared with the fibers, and this adsorption prevented them from further aggregation and deposition.Thirdly, when study the agglomeration behavior of microstickies in suspension; it was found that EMMA put up a behavior of periodic variation and it could be measured by the content of colloidal organics, if the content of microstickies in suspension was higher than critical value, then the periodic pitch/stickies deposit would happen.?-CD could reduce the stickness of stickies via increasing its wetting and swelling ability, could decrease the easily-changed inclination of microsickies size and amounts as well as decrease the agglomeration liability of microstickies. What's more, with the extensive application of the fillers such as GCC,PCC and TALC in Package Paper, they could lead to the increase of the deposit because of their adhering to the sticky stickies and deposit together with them, especially serious when the fillers and the destabilized secondary stickies were not well adsorbed to the fibers at low cationic polymers addition. After fillers adding, the increased amounts of stickies deposit were much more than that of fillers in deposits. Different fillers would have different effect on the deposition. Comparing with TALC, PCC addition would result in less deposit at high dosage of cationic polymers.Last but not least, flow Cytometer with a function of particle sorting was introduced into studying the amounts and size of stickies in suspension. After treatment with different fixatives, different changes of amounts and size of stickies could be determined by Flow Cytoeter, this would help to estimate the forming tendency of stickies as well as make a right choice for stickies controlling agent, and avoid the occurrence of stickies deposit.