Patent ID: 7569526

Claim:
A composition, comprising: at least one metalworking fluid comprising a water in oil metalworking emulsion wherein the oil phase consists essentially of naphthenic mineral oil, an emulsifier for the naphthenic mineral oil, 0.25 wt. % of an antioxidant selected from the group consisting of butylated (30%) and octylated (24%) diphenylamine and butylated (45%) and octylated (19%) diphenylamine, and 0.25 wt. % of a 1,3,5-tris(2-hydroxyethyl)-S-triazine; wherein the diphenylamine and the 1,3,5-tris(2-hydroxyethyl)-S-triazine are present in amounts sufficient to reduce biological degradation by delaying bacteria onset by at least 18 weeks following a 1 day incubation period in accordance with ASTM 3946.