Photoreactive hyperbranched urethane acrylates modified with a branched saturated fatty acid

Abstract

Urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP) were synthesized. HBP of the second and the third pseudo-generation were synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of 60% of the OH end-groups was carried out with isononanoic acid. Urethane acrylates with different degrees of acrylation were obtained by reaction of partially modified HBP and different amounts of acrylate-isocyanate adduct (NCO), which had been previously obtained by reaction of equimolar amounts of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by FT–IR, 1H and 13C NMR spectroscopy and GPC. The rheological properties of uncured samples and the mechanical and thermal properties of UV cured urethane acrylates diluted with 20 wt.% hexanediol diacrylate were examined. The modification of the OH end-groups with isononanoic acid caused a rapid decrease in the viscosity of the HBPs. The examined properties of the urethane acrylates mainly depended on the degree of acrylation.