F+L Week 2017 | Jimmy Yinjun Zou | Meeting MWF Longevity Requirements without Formaldehyde-Condensate Biocides, Boric Acid and Secondary Amines
Water-dilutable metalworking fluids (MWFs) are susceptible to shortened fluid life, due to numerous species of bacteria and fungi presented in the working environment. One of the common strategies is to formulate with components that control the growth of microorganisms and resist biological degradation. As such, formaldehyde-condensate biocides, boric acid or boron condensates, and secondary amines like dicyclohexylamine (DCHA) are widely adopted in formulations as effective ways to extend the fluid life. However, both regulatory authorities and end-users are imposing higher standards on components used in MWFs. This trend is driven primarily by health, safety and environmental concerns on the harmful compounds listed above. Consequently, the industry is inclined to reduce or eliminate the above- mentioned classes of compounds in the formulations. Unfortunately, it is challenging to maintain the performance and longevity of MWFs in the absence of these compounds. ANGUS Chemical Co. (ANGUS) has dedicated significant amount of effort to develop and provide specialty additives for water-miscible fluids that help improve performance and extend fluid life. A variety of primary amino alcohols and corrosion inhibitors are marketed under the CORRGUARD® brand name. In an effort to discover suitable replacements for triazine, boric acid, and DCHA, ANGUS has developed and introduced new products into the CORRGUARD family. In this presentation, the newly developed chemistry used in combination with registered formaldehyde-free biocides will be presented. The ability of this combination to approach or exceed the performance of conventional formulations with triazine, boric acid, and/or DCHA will be demonstrated. Key parameters of pH stability, microbiological resistance to field isolates of bacteria and fungi, cast iron corrosion, aluminum staining, and residue rinsability were studied. Results showed that semi-synthetic MWFs comprising of a primary amine stream, 3- amino-4- octanol, and non-formaldehyde releasing biocides were good candidates to replace undesirable formulations containing formaldehyde-condensate biocides, boric acid, and/or DCHA. Formulations containing CORRGUARD products also demonstrated excellent performance with a variety of biocides, especially benzisothiazolinone. Improved fluid life, pH stability, and multi-metal compatibility were shown.