A high-purity cardanol derived from renewable cashew nutshell liquid offers chemical features that can be successfully used in epoxy and polyurethane adhesives and sealants.
Cashew nutshell liquid (CNSL) is a non-edible, bio-based material commonly used as a building block for various resins, hardeners, and modifiers in the adhesives, coatings, and composites industries. A high-purity cardanol, 3-pentadeca-dienyl-phenol, derived from the bio-oil CNSL has been employed to replace nonyl phenol (NP) in various applications, including isocyanate blocking. Cardanol has shown many benefits (e.g., low viscosity, lower deblocking temperature, environmentally friendly) over NP and phenols as an isocyanate blocking agent. However, high deblocking temperature has limited the use of cardanol in some applications.
One of the most known deblocking pathways involves exposure to elevated temperatures (150-200°C). However, not all the substrates (e.g., plastics) and applications can accommodate such high temperatures for deblocking. Therefore, the possibility to optimize the deblocking conditions can be a valuable tool to further expand the applicability of cardanol as a label-friendly polyurethane prepolymer blocking agent.