Radiation curing of epoxy-acrylate prepolymers and their mixtures with vinyl monomers, 4

Several coatings, cured by electron beams, were prepared with the mixtures of epoxy-acrylate, vinyl monomer and various pigments. Anticorrosive tests were carried out in order to find suitable pigments for the purpose. A mixture of bisphenol A type epoxy-acrylate (mean molecular weight=520) and 2-hydroxypropyl methacrylate (52/48) was chosen as a coating vehicle. Three types of iron oxide and two types of zinc chromate were used as pigments. Doses required for curing, hardness and adherence of the cured coatings didn't differ so much from those of pigmented ones (20%). Viscosities of the paints became slightly higher when iron oxide pigments were added, while the viscosities markedly increased when zinc chromate pigments were used. Some coatings showed excellent resistance to salt water immersion with test specimens scratched crosswise on the surface. The stability in storage decreased for the paints containing zinc chromate pigments in the presence of acrylic acid in the vehicle. Red iron oxide was generally found to be the most suitable among the pigments tested. (author)