Vanillin-based UV curable polyurethane dispersions

Researchers have demonstrated the synthesis of vanillin-based UV curable polyurethane dispersions for wood coating applications.

Wood easily degrades without sufficient preservation. Apart from structural wood preservation measures, there are a number of different chemical preservatives and processes that can extend the life of wood. Image source: Petair - AdobeStock (symbol image).

During the study, the partial incorporation of bio-based diol in the synthesis of UV-curable polyurethane dispersion (PUDs) has been studied. The bio-based diol was synthesised from vanillin. Divanillin (DV) was used as a partial replacement for polyethylene glycol an industrial diol. PUDs were synthesised by reacting vanillin and polyethylene glycol in different percentages (10:90, 30:70, and 50:50) with isophorone diisocyanate along with 2-dimethyl propionic acid. The synthesised resin was dispersed in water and applied on a wooden panel. Mechanical testing was carried out on the cured coatings to determine their properties.

Excellent acid resistance

The 30% incorporation of DV shows the highest pencil hardness (2H) and scratch hardness (0.90 kg) among all the DV formulations and the results were comparable to plain formulation. The 30% DV also exhibits good gloss at 60° angle with value of 76.7. Coatings exhibited excellent acid resistance and moderate resistance towards alkalis. TGA was performed on the plain PU and 30% DV and the onset temperatures were 190 °C and 185 °C, respectively.

The review has been published in Journal of Coatings Technology and Research, Volume 20, Issue 5, September 2023.

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