Hydrophobic polyurethane powder clear coatings with lower curing temperature: Study on the synthesis of new blocked polyisocyanates
Dominika Czachor-Jadacka, Barbara Pilch‐Pitera, Łukasz Byczyński, Maciej Kisiel, Aleksandra Zioło
Abstract
The method of the synthesis of blocked polyisocyanates (bPIC) used as a crosslinking agent for hydrophobic and low temperature curing powder coatings was developed. In the synthesis of polyisocyanates (PIC) isophorone diisocyanate, glycerine, xylitol, polyethylene glycol and polysiloxane KF-6000 as well as two different blocking agents, i.e. acetone oxime and butanone oxime were used. The chemical structure of the obtained blocked polyisocyanates was confirmed by IR and NMR spectroscopy and the molecular mass distribution was investigated using gel permeation chromatography (GPC). The thermal behavior and the deblocking process were investigated by means of TG, DSC and DMA. The obtained coatings were evaluated by performing the following tests: roughness, gloss, scratch resistance, hardness, adhesion to the steel and water contact angle. As part of this research, the hydrophobic and high scratch resistance coatings cured at 150 °C were developed.