The influence of coalescing solvents on stability and performance of water-borne coatings

 
Coalescing solvents are an important yet rarely researched component of waterborne coatings. To understand why certain solvents give better films and why some cause problems the underlying interactions were investigated. The results show that hydrophilic solvents tend to solvate the binder particles rather than swell them. Such solvation weakens ionic stabilisation and can lead to binder shock and film defects which can be avoided by using more hydrophobic solvents. However, a newly developed method based on Electrochemical Impedance Spectroscopy revealed that hydrophilic solvents can be more efficient filming aids so it's recommended to solve this problem by using more robust binder dispersions or by choosing the correct coating preparation procedure. The novel approach has proved to be very powerful for optimising the composition of coalescing aids in real-world coating formulations.