LONG POT LIFE
CNSL-based novolac resins (NX-4000 Series) are a new family of high bio-content phenolic resins that can be formulated as epoxy crosslinkers in long pot life, heat-cured systems. This class of low and high viscosity novolacs is high in functionality and equivalent weight. These products give excellent moisture and chemical resistance, and improved wetting properties and interlaminar shear strength and adhesion to composite parts.
CNSL novolacs have very good miscibility with epoxy resins and could be alternatives to or used in combination with petroleum based phenolic resins depending on the system. They are suitable as high biocontent, increased flexibility replacements of latent amines and anhydride curing agents in long pot life and latent systems. CNSL novolacs do not react with epoxy at room temperature, but react at moderate temperatures (80-120°C) in the presence of a catalyst such as imidazole, urone, or Lewis acids. Among the suggested accelerators are 2-ethyl,4-methylimidazole, 2-methylimidazole, blocked imidazole and boron trifluoride complex. The choice of the catalyst determines the pot life of the formulation and the cure time at different temperatures.
These novolacs can be used in one or two component epoxy formulations.