International. Coalescings are organic solvents that are widely used to accommodate the film formation of water-based coatings. Slovenian researchers have analysed the influence of coalescing aids on the latex properties of water-based coatings.
The results revealed that coalescing increased viscosity through swelling and solvation of the particles, the effect being stronger with more hydrophilic solvents.
Results obtained with electrochemical impedance spectroscopy (EIS) and indentation tests showed that hydrophilic coalescing was more efficient due to partitioning at particle interfaces, but could temporarily decrease water resistance.
The ease of coalescence was countered by solvent retention, which complicated the dynamics of the film's formation. The EIS was used to optimize a real-world coating formulation and identify hazards arising from the complex dynamics of film formation. The best moisture resistance was obtained with a combination of hydrophobic and hydrophilic coalescence aids.
Source: Applied Polymer Science.
