Epoxy Novolac Resin F-51 (High Functionality)

Epoxy Phenol Novolac Resin F-51 is a multifunctional epoxy produced by the epoxidation of phenol-formaldehyde novolac with an average functionality of 3.5-4.0 epoxide groups per molecule. The high epoxide functionality results in a highly cross-linked network on cure, providing significantly higher Tg (150-200°C), better chemical resistance, and higher strength at elevated temperatures compared to difunctional BPA epoxies.

F-51 is available as a high-viscosity liquid or low-melting-point semi-solid (softening point 50-80°C depending on molecular weight) in xylene or other solvents for processing convenience. EEW is 175-195 g/eq. The resin is widely used in aerospace and industrial thermoset matrices, electrical laminates (particularly FR4/CEM printed circuit boards), powder coatings for pipes, and high-temperature resistant adhesives.

In prepreg applications, F-51 is blended at 15-40% loading with BPA epoxy to raise the composite Tg to 150-180°C while controlling cost. In electrical FR4 laminates, F-51 provides the high-temperature performance needed for lead-free solder reflow (Tg >150°C requirement). Chemical resistance (concentrated acid, base, solvent immersion) is superior to BPA epoxy due to higher cross-link density.