Sustainable solution - CNSL technology for high-performance protective epoxy coatings

 
Epoxy systems are widely utilized in the Coatings, Adhesives, Sealants, and Elastomers (CASE) industry due to their exceptional mechanical properties, chemical resistance, anti-corrosion performance, and durability in harsh environments. In the past decade, the coating industry has faced the increasing regulatory and sustainability demands, including the reduction of volatile organic compounds (VOCs) and the incorporation of bio-based and environmental-friendly alternative materials. Formulators are seeking solutions that help meet these stringent regulatory requirements and sustainability goals without compromising high performance. Cashew nutshell liquid (CNSL) technology has emerged as a sustainable and innovative solution to these challenges. CNSL is an annually renewable, bio-based material derived from the inedible waste of the cashew processing industry. Cardanol, a major component of CNSL with over 98% bio-content, serves as a versatile "building block" for producing bio-based derivatives with diverse functionalities for a range of CASE applications. CNSL-based products can offer significant sustainable advantages, including non-food chain sourcing, non-toxicity, favorable regulatory labeling, and a low carbon footprint; and for protective coating systems, they can provide performance benefits such as hydrophobicity (better water resistance), rapid curing at low temperatures, good chemical resistance, and enhanced adhesion over various substrates. This paper presents recent developments in CNSL-based solvent-free (SF) products, with a particular focus on the low viscosity SF epoxy curing agents and multi-functional modifiers used in SF and ultra-high solids epoxy primer systems. Performance studies demonstrate that the new CNSL-based curing agents offer rapid curing at low temperatures, good water resistance and chemical resistance. Formulation studies reveal that the incorporation of CNSL-based multi-functional modifiers helps improve flexibility and mechanical property. Anti-corrosion and cathodic disbondment tests further indicate that CNSL-based products provide good water resistance and protective performance.