MBT (2-Mercaptobenzothiazole)

Both MBT and BTA form protective films on copper surfaces, but through different mechanisms. BTA forms a polymeric Cu-BTA complex that provides excellent protection at very low concentrations (1–5 ppm). MBT forms a Cu-MBT film and also provides some biocide activity. BTA is generally preferred for copper protection in cooling water and antifreeze; MBT is preferred when biocide activity is also needed. Contact Texas-Chem at 855-TEX-CHEM for application guidance.

MBT is slightly soluble in water (0.3 g/L) but dissolves readily as the sodium salt (NaMBT) in alkaline solutions. To prepare a working solution, dissolve MBT in dilute sodium hydroxide solution (pH 9–10) to form NaMBT, then add to the water-based system. Alternatively, use pre-dissolved NaMBT liquid concentrate. Contact Texas-Chem for NaMBT availability.

MBT is typically used at 0.05–0.5% by weight in metalworking fluid concentrates, which dilutes to 5–50 ppm in the working emulsion. The treat rate depends on the copper content of the machine tool components and the severity of the machining operation. Contact Texas-Chem at 855-TEX-CHEM for formulation guidance.

MBT is compatible with soluble oil (emulsifiable oil), semi-synthetic, and synthetic metalworking fluid types. It is not compatible with strong oxidizing agents or strong acids. In alkaline metalworking fluids (pH 8.5–9.5), MBT provides excellent copper protection. Verify compatibility with other additives in your formulation before use.