Application of weak cationic polyelectrolytes in paper and cardboard efficiency improvment technology

The article considers the effect of weak cationic polyelectrolytes on the structure- and paper-forming properties of glued fibrous suspensions and the quality of glued and coated paper and cardboard samples obtained from them. It is shown for the first time that the efficiency of using cationic polyelectrolytes increases by 2…3 times due to a change in the sequence of its introduction into glued fibrous suspensions (cellulose and waste paper) in relation to rosin emulsion and electrolyte, as well as by «correction» their dosages. It is found that the use of the developed technology allows cationic polyelectrolytes to participate not only in the process of flocculation, but also in the formation of new sizing complexes in the form of finely dispersed positively charged peptized particles. It is revealed that the replacement of the sizing process in the homocoagulation mode with a more efficient mode of heteroadagulation of peptized particles due to the use of weakly basic cationic polyelectrolytes provides an increase in hydrophobicity and strength of the glued types of paper and cardboard. The expediency of using cationic polyelectrolytes to obtain high-quality products in the developed resource-saving and ecologically safe technology of glued types of paper and cardboard is substantiated based on the established increase in the degree of retention of fibers and sizing complexes and the simultaneous decrease in the content of suspended solids in recycled water. It is determined that the coating of glued paper and cardboard samples obtained with weakly basic cationic polyelectrolytes improves the printing properties of the resulting products. Recommendations are given for replacing the traditionally used complex of natural compounds in the coating paste formulation, including oxidized starch (2,0 parts by weight), sodium carboxymethyl cellulose (0,7 parts by weight) and casein glue (2,0 parts by weight), for one synthetic binder — modified urea-formaldehyde oligomer (3,2 parts by weight).