Developing an industrial friendly process for hydroxymethyl resorcinol (HMR) priming of wood using a novolak-based HMR
Publication Name: Forest products journal
Publication URL: https://agris.fao.org/agris-search/search.do?recordID=US201301031906
Creating exterior durable bonds to wood using epoxy adhesives or other nonaqueous adhesives often requires the application of a primer or coupling agent. For durable wood-to-wood and wood-to-fiber-reinforced-polymer (FRP) bonding, the use of a hydroxymethylated resorcinol (HMR) coupling agent is recommended as a primer. In this paper, an experiment aimed at reducing the processing time required for HMR priming using a novolak-based HMR primer and the application of infrared heat emitted from lamps is described. This experiment evaluated the sensitivity of the entire HMR-adhesive system by assessing important process variables including HMR drying time, spread rate, and solids content. The experiment utilized a quick, accurate, and widely used technique to evaluate both shear strength and percentage of wood failure: a compression shear block test. The best bonding performance was measured at a novolak-based HMR drying time between 15 and 20 minutes. Both test conditions showed a high shear strength combined with a high percentage of wood failure. Finally, this experiment contributed to the knowledge required for the development of an industrial friendly process using HMR as a wood primer.