Polyurethane coatings prepared from CNSL based polyols: Synthesis,characterization and properties

Conventional polyurethane chemistry based on polyol and isocyanate chemistry is widely used for many applications ranging from plastics to coatings, constructions, pharmaceuticals, foods, etc. The growing concern over depletion of petrochemical materials and their rising prices has led to search for environment friendly renewable materials. Cardanol derived from cashew nut shell liquid is one such renewable material which has reactive phenolic group and aliphatic double bond that could be tailor-made to produce novel functional materials for polymer and coating applications. This has previously been used for preparation of phenolics, epoxy resins and phenalkamine hardners. Diglycidyl ether of cardanol which is commercially available, is used as epoxy resin or modifier in epoxy formulations. In the present work, this was modified by simple one step ring opening reaction to produce polyols with different number of functionalities. The various polyols prepared were cured with polyisocyanate cross-linkers and applied on metallic substrates. The cured coatings were evaluated for physical, mechanical, chemical and thermal properties. The study conducted showed that the prepared polyols could be used as sole binder for coating formulation with overall excellent properties.