A novel photocurable modified epoxy resin for high heat resistance coatings

Abstract

In this paper, in order to further improve the heat resistance of UV-curing epoxy cresol novolac (EOCN), 2,2-bis(hydroxymethyl)propionic acid (DMPA) was firstly introduced to open epoxy groups in EOCN and then the hydroxyl groups reacted with acryloyl chloride to make sure the resin has sufficient UV-curing double bonds. Compared with the system that uses acrylic acid to open epoxy group and the secondary hydroxyl group reacting with unsaturated anhydride, up to 1.5 times double bonds were potentially introduced. The structure of the resins was characterized by FT-IR and 1H-NMR. Influences of double bond content on thermal behavior, photopolymerization kinetic behavior, and basic properties of the cured films were investigated. Thermal performance analysis demonstrated that the glass transition and the initial decomposition of the cured films were increased with the rising proportion of acryloyl group. Moreover, doping of abundant acryloyl chloride caused a significant increase of unsaturated double bond conversion, though the initial photopolymerization rates declined. Cured films with less acryloyl chloride modified showed better adhesive. For solvent-resistant test, with the increase of the acryloyl group, the cured film displayed good resistance to strong acids and alkalis. These attractive features give this process potential applications in soldering ink and protective coatings.