Investigating the Possibility of Using Bentonite as a Retention Aid for Filler Printing and Writing Paper

One of the methods for material management and cost reduction in paper industry is the attempt to maintain a longer shelf-life of fine paper pulp components such as fiber fines, mineral additive(fillers).This research was carried out to replace bentonite as a retention aid due to the native, it was cheaper and more accessible than polyacrylamide. In this research, the effect of polyacrylamide, bentonite and blending of bentonite and cationic starch on paper printing and writing containing 20% ​​filler paper was evaluated in one of the paper mills, and the trend of change in water drainage, retention and characteristics resistance and light were investigated. Decreasing dewatering time was happened in the combination of cationic starch and bentonite, such as cationic polyacrylamide, due to the high ability of a cationic polymer of starch composition to be combined with bentonite minerals in the formation of the flock in the suspension and more water absorption potential. With increasing percentage of ash in the presence of bentonite, no significant change was observed in the components' durability, but the components remained more in the presence of cationic starch and bentonite, and were approximately the same as in the use of polyacrylamide. The stretch strength index was decreased due to weak formation, this decrease was also lower than that of polyacrylamide; however, in the tear resistance, an increasing trend was observed and was still lower than that of polyacrylamide. The opacity of papers containing bentonite and cationic starch showed a slight decrease in the presence of cationic starch, but only bentonite paper showed a higher opacity. There was no significant change in the degree of brightness in all treatments compared to polyacrylamide treatments.