A Biobased Reactive Accelerant And Diluent For Solvent-Free Drying Oils

Drying oils are unsaturated plant oils, widely used in paints and varnishes. The inclusion of solvent thinners and metal catalyst accelerators in drying oil formulations may be problematic from an environmental perspective. We report on the development of a biobased alternative that can act as both a reactive accelerant and a viscosity modifier for solvent-free drying oil systems. The ozonolysis of canola oil and linseed fatty acid methyl esters (FAME) produced compounds that were shown to be effective in directly adding to conjugated carbon-carbon double bonds (-CH=CH-) resulting in faster polymerization. For tung oil, substitution with 25 wt.% of ozonized linseed FAME reduced the drying time by 70% and the viscosity by 60%, while the glass transition temperature approached that of a pure linseed oil film. The drying time reduction effect was found to be strongly dependent on the concentration of ozonized lipids but not greatly influenced by the ozonolysis time. For tung oil, a conjugated drying oil, incorporation of up to 65 wt% ozonized lipids was possible, resulting in dried films within less than 1 h at 60 degrees C and a 90% viscosity reduction while maintaining up to 100% biorenewable content and air-induced polymerization.