Optimization of asa emulsification in internal sizing of paper and paperboard

In paper and paperboardmaking, internal sizing is used for making the end product more resistant to liquid penetration. Rosin, Alkyl Ketene Dimer (AKD) and Alkenyl Succinic Anhydride (ASA) internal sizing agents exist for this purpose. ASA is added to the papermaking process in the form of an emulsion. The dispersion of ASA, water, and an emulsifier are mixed under shear forces to create the capsulation and emulsion. In this master's thesis, various ASA and ASA emulsifiers with various emulsification techniques in both laboratory and industrial process scale were studied. The goal was to find best performing ASA, best coupling ASA emulsifiers, best conditions for emulsification and paper machines and to have proper emulsion with proper ASA:emulsifier ratio, particle size&visual check of emulsion, cobb&porosity values of produced papers. Together with three various ASAs, the emulsifiers were various cationic starches, polyacrylamides and polyethyleneimines having various charge densities and molecular weights, so that six emulsifiers which gave steric or electrostatic stabilization and capsulation effect on emulsion droplets. Particle size and visual determinations and Cobb 60 tests were carried out and three emulsifiers and one ASA were selected for industrial utilization. ASA dosages of 1-5 kg/ton of paper together with two emulsifiers (C-PAM and cationic liquid starch) performed commonly well in all laboratory and industrial process scale experiment with mixing ratio from 0,5 to 1,8 was utilized to make paper sheets and paper reels. Water absorption tests showed that the best hydrophobation with ASA with C-PAM and ASA with cationic liquid starch. A good ASA emulsion particle size was in between 0,5 µm – 3 µm in diameter values. The most stable emulsions were white and had no phase inversion, only little creaming and foaming during at least 2-hour-study. After all experimental work done, Cost analysis and savings in industrial trials were taken into consideration for ASA with C-PAM and ASA with starch emulsifiers.