Blocked polyisocyanates as crosslinking agents for polyurethane powder coatings

Researchers have studied the synthesis of new blocked polyisocyanates as crosslinking agents for hydrophobic polyurethane powder clear coatings.

Blocked polyisocyanates as crosslinking agents for polyurethane powder coatings. Source: Pixabay -

The crosslinkers were synthesised using isophorone diisocyanate (IPDI), formic acid and ε-caprolactam and modified with fluorinated polyols. For the synthesis, two kinds of catalyst i.e. dibutyltin dilaurate and dibutyl phosphate were employed.

Improved thermal stability

During the thermal degradation of modified polyisocyanate three main stages of decomposition can be seen. The degradation of modifier occurs in the last decomposition stage at temperature range of 375–500°C. Additionally, PU powder clear coatings composed of polyester binder and modified blocked polyisocyanate were examined. The cross-linked polyurethane powder clear coatings resulted in improved thermal stability and surface properties i.e. lower roughness and surface free energy values as well as higher hydrophobicity, oleophobicity, gloss, scratch and abrasion resistance.

The study is published in: Progress in Organic Coatings, Volume 113, December 2017.

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