The reaction of cardanol, formaldehyde, and certain amines is called a phenalkamine. Phenalkamines share some similar advantages to other base curing agents, such as: extremely fast cure, low temperature cure (even below 0°C), good chemical resistance, good surface appearance, good moisture tolerance, and non-blushing properties. However, due to the long aliphatic side chain of cardanol, phenalkamines also have very good pot life, good flexibility, surface tolerance, and excellent water and salt water resistance. Many phenalkamines are also approved for use in food contact and potable water coatings.
The fast and low temperature cure properties of phenalkamines have a number of benefits for coating formulations. Application productivity can be significantly improved and the ability to apply a coating in low temperatures allows for a longer or even year round painting season. Faster cure also means protected surfaces can be re-coated or returned to service more rapidly, including solvent free formulations that will continue to cure when immersed in water and solvent based coatings that will continue to cure in poorly ventilated conditions. In forced cure industrial coating applications, phenalkamines can help save energy by lowering oven cure temperatures, or improving process efficiency via increased production line speeds. Finally, fast cure can also help protect coating manufacturers from coating failures. By reaching a high level of crosslinking very quickly, coatings develop their stability early and avoid problems when the environmental conditions change after application.
The high hydrophobicity of phenalkamines provided by the long linear side chain also brings many benefits to coating formulations compared with some other technologies. Water sensitivity of the phenolic hydroxyl and other formulation components can be counteracted, which reduces the chance the resin binder barrier will be broken and increases corrosion protection. Adhesion to poorly prepared or tough wet surfaces, such as water saturated concrete is especially good with phenalkamines because this hydrophobic effect ensures surrounding water does not influence the surface resin bond.
With over three decades of research, this is new developments in phenalkamine technology such as innovative solvent-free, low viscosity, and faster curing products.