Process variables and the performance of soybean-oil rosin-based polyester as an internal sizing agent

Soybean-oil rosin-based polyester (SRP) has many uses in papermaking, but its performance as an internal sizing agent differs depending on the circumstances. In this study, a comprehensive laboratory approach was used to investigate the process variables affecting SRP application. Five levels of SRP (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), five levels of aluminum sulfate (0.5%, 1.0%, 1.5%, 2.0%, and 2.5%), and five levels of cationic polyacrylamide (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) were considered to determine the best process variables within a pH range of 5.0 to 9.0. Aspects that were considered included the mechanical properties (tensile, burst, and tear indices), water resistance (Cobb test, dynamic c9197ontact angle test, and scanning electron microscopy), and chemical usage (economical and environmentally friendly procedures). The optimum conditions based on these factors were 1.0% SRP, 1.0% aluminum sulfate, and 0.15% cationic polyacrylamide levels at a pH of 7.0. The results showed that in the optimal sizing system, 15% calcium carbonate can be tolerated.