Reformulation of Alkaline Copper Quat for Enhanced Copper Leaching Resistance

Abstract

To ensure the environmentally safe usage of copper amine-based wood preservatives in aquatic environments, it is necessary to minimize copper leaching from treated wood. In this study, alkaline copper quat (ACQ) was reformulated to enhance resistance to copper leaching by adjusting the proportions of copper, didecyldimethylammonium chloride (DDAC), and mono-ethanolamine (Mea) solvent. The copper proportion in the formulation was decreased 40% while maintaining the total retention of active ingredients through increasing DDAC. The molar ratio of Cu to Mea in the formulation was then adjusted from 1:4 to 1:2.75. This reformulation shortened the time to copper stabilization from 15 to 6 days, and reduced cumulative copper leaching by 75%, compared to a control formulation. These fixation properties were further improved with just a 30-min hot-air post-treatment at 100 °C. Wood treated with the reformulated ACQ exhibited comparable performance in biological efficacy against fungi and termites compared to wood treated with commercial ACQ.