Effect of cationic polymers, salts and fibres on the stability of model micro-stickies

The stability of micro-stickies is of great concern to papermakers as these materials, when they agglomerate, can deposit on equipment and on the pape r product. The charge demands of an acrylic microsphere adhesive emulsion ( a model for micro-stickies), a softwood market pulp and different starches were determined by titrations with standard polymer solutions. The effects of fibers, different cationic polymers and salts on the stability of the mi cro-stickies were investigated using a turbidity meter and a hemacytometer: The agglomeration of micro-stickies with Poly-DADMAC occurred mainly via a charge neutralization mechanism. In contrast, the agglomeration of micro-s tickies with cationic starch had a move complicated behavior: Both Poly-DAD MAC and cationic starch stabilized the micro-stickies when present in exces s, The micro-stickies have a double layer and were observed to obey the Shu ltz-Hardy rule. It was determined that common levels of Al3+ ill papermakin g are sufficient to precipitate micro-stickies. The anionic fibers/fines an d micro-stickies compete for the cationic polymer present in the system. Th e more hydrophobic micro-stickies are more readily agglomerated than the fi brous fine material.