Application of vinyltrimethoxy silane as moisture scavenger for the high reactive 2k polyurethane coatings: Physicochemical and kinetic studies

Abstract

The 2k-polyurethane coating can be formed by simple addition of hydroxyl group containing materials to isocyanate group containing materials. The high reactivity of the aromatic diisocyanate results in absorption of moisture and liberation of CO2 bubbles at room temperature leading to undesired defects in applied coatings. Here, we investigated the effect of vinyltrimethoxy silane (VTMS) as moisture scavenger in the polyurethane coatings and its reactivity towards water and diisocyanate. The mechanism of formation of polyurethane in the presence and absence of the VTMS was successfully described by different techniques (FTIR-ATR measurements of diisocyanate transmittance at wavenumber 2272 cm− 1). The activation energies were 19.04 and 17.38 kJ/mol in the presence and absence of the VTMS, respectively. This indicates that under high temperature and high relative humidity conditions, the VTMS led to fast and safe reaction. It was found that the final coating properties like gloss and hardness were improved where the VTMS undergoes chain reactions with both humidity and diisocyanate as well as participates in the final polyurethane network.