Dispersants for latex paint are divided into four categories: phosphate dispersants, polyacid homopolymer dispersants, polyacid copolymer dispersants, and other dispersants.
The most commonly used phosphate dispersants are polyphosphates, such as sodium hexametaphosphate, sodium polyphosphate (Calgon N, BK Giulini Chemical Company, Germany), potassium tripolyphosphate (KTPP), and tetrapotassium pyrophosphate ( TKPP). Its mechanism of action is to stabilize electrostatic repulsion through hydrogen bonding and chemisorption. Its advantages are low dosage, about 0.1%, and good dispersion effect on inorganic pigments and fillers. However, there are also shortcomings. First, as the pH value and temperature increase, polyphosphates are easily hydrolyzed, resulting in poor long-term storage stability. Second, polyphosphates are used in glycol solvents such as ethylene glycol and propylene glycol. Incomplete dissolution will affect the gloss of glossy latex paint.