For paint to have suitable properties, whether for decorative purposes for its final look, or strictly functional, such as the protection of a given substrate, the choice of basic components is crucial. Film-forming agents, also known as coalescent agents, are among these components and are directly linked to one of the most critical processes in paint development—paint film-forming during drying.
Paints can be made in a number of ways. The simplest is based on the dissolving of a polymer in a solvent, whose film-forming process involves three main stages: application, fixing, and drying. In this process, the solvent plays a key role in the quality of the paint’s film-forming, so it must be chosen correctly.
In the specific case of water-based systems, the film-forming process is a little more complex and requires the use of agents that boost the coalescence of polymeric particles (latex). These coalescing agents can be produced in different ways, based on their ability to bring about homogeneous film-forming from latex. They plasticize the polymer phase in paint formulations, reducing the temperature necessary to deform polymer particles, helping to form a continuous and homogeneous film.
Coalescing agents, therefore, play a key role in the latex film-forming process. These molecules mainly help in the final stage of particle coalescence. In practice, coalescing agents are solvents that plasticize the polymer phase in paint, enamels, and adhesives formulations, thereby, reducing their transition temperature and boosting particle deformation, as well as the interdiffusion of the polymer chains.
By improving the performance of paint film-forming, the coalescent thus ensures continuous and homogeneous paint film-forming under different temperature and humidity conditions. The final result then has a superior finish and greater water resistance, in addition to being less vulnerable to leaching and dirt pick-up.
