Meeting Metalworking Fluid Longevity Requirements without Boron, Formaldehyde Condensates and Secondary Amines
February 21, 2017
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Water-dilutable metalworking fluids are susceptible to shortened fluid life, due to the presence of numerous species of bacteria and fungi.
Fluids have therefore been formulated with components which control microorganisms and/or resist biological degradation. Examples include formaldehyde condensate biocides like GROTAN® (78% hexahydro-1,3,5-tris-(2-hydroxyethyl)-s-triazine), boric acid or boron condensates, and secondary amines like dicyclohexylamine (DCHA). Regulatory actions and fluid end user preferences, driven primarily by health, safety and environmental concerns, are leading the industry to reduce or eliminate the use of these classes of compounds, at least in some countries. Maintaining metalworking fluid performance and longevity in the presence of microorganisms is more challenging when some or all of these compounds are eliminated. This paper discusses the use of certain primary amino alcohols, in combination with non-formaldehyde releasing biocides, and compares performance with systems containing 0-5% boric acid and GRO TAN, or DCHA and non-formaldehyde biocides, in the presence of hydraulic oil contamination. The performance of a high oil semi-synthetic fluid with 2.5% boric acid and 2% GROTAN is easily exceeded using DCHA or a primary amino alcohol combination (2-amino-1-butanol, 2-amino-2-ethyl-1,3-propanediol and 3-amino-4-octanol), together with several non-formaldehyde biocides. Additionally, the primary amino alcohol combination with certain non-formaldehyde biocides approaches the performance of 5% boric acid and 2% GROTAN.