Dibasic acid mixtures ranging in length from C10 to C12 (Sebacic Acid, Dodecanedioic Acid (DDDA) and Undecanedioic Acid) can be formulated as an amine salt concentrate for a variety of corrosion inhibition applications. This mixture creates a strong protective layer of inhibition on a metal surface and is especially effective at ferrous corrosion protection for metalworking fluids, cleaners, hydraulic fluids, die cast release agents and cooling application. Because the dibasic acids are produced from natural feedstocks, it is a biodegradable and is an environmentally sustainable solution for corrosion protection in bio-lubricants. This mixture is a desirable over amine borate formulations because it does not leave hard-to-clean residues. It also is low foaming and has good hard water stability.
The table below shows a suggested basic formulation for creation of the aqueous amine salt. Modifications can be made as necessary for desired results including use of additional C4-C9 Dibasic acids, or substitution with other amines such as Monoisopropylamine (MIPA) or 2-Amino-2-Methyl-1-Propanol. This concentrate can be formed by heating to 40-75 °C and should result in a clear solution with a final pH of 9.0-9.2.
TABLE 1: Amine Salt Concentrate
| Dodecanedioic Acid | 1.5 – 2.25 wt. % |
| Undecanedioic Acid | 1.5 – 2.25 wt. % |
| Sebacic Acid | 0.25 – 0.5 wt. % |
| Monoethanolamine (MEA) | 5.0 wt. % |
| Triethanolamine (TEA) | 5.0 wt. % |
| Water | 85.0 wt. % |
Modifications to this basic formulation can be made for the creation of a variety of metalworking fluids including synthetics, semi-synthetics, and soluble oils. The corrosion inhibition performance of such formulations have been tested using the ASTM cast iron chip test (D 4627) and have been found to be superior in lower concentrations to using one dibasic acid alone.