Study of parameters determining inter-particle crosslinking reactions in waterborne coatings.

Abstract

This PhD thesis aimed to study of the interparticle crosslinking reactions in waterborne coatings, as a way to overcome the film formation dilemma and produce hard coatings with less coalescing agents. For that, the crosslinking chemistry between acetoacetoxy ethyl methacrylate and amine functionalities was used, due to its lower toxicity compared to other crosslinking functionalities. Furthermore, it was decided to place both crosslinking moieties on the polymer particles, and not as water soluble species, in order to prevent REACH regulations.The crosslinking chemistry was followed by FTIR, rheological measurements and interparticle diffusion measurements. It was seen that crosslinking reaction proceeded slowly at room temperature, needing several days to attain full conversion, while it accelerated significantly at 65 ºC. Once the properties of the so crosslinked films obtained from particles of component 1 and 2 with the same particle size and Tg was analysed, the effect of varying the particle size and the Tg of both components was investigated.Finally, the obtained waterborne dispersions were included in wood coating formulations and their performance was analysed as compared to a commercial product.