Water-miscible metal working fluids with reduced aerosol inhalation toxicity

Abstract: The present invention provides a process for producing a water-miscible metalworking fluid involving combining about 90 wt. % to about 5 wt. %, based on the weight of the fluid, of water and one or more additives chosen from plasticizers, chelating agents, biocides, surfactants, dispersants, dyes, odorants, extreme pressure agents, anti-oxidants and corrosion inhibitors with about 10 wt. % to about 95 wt. %, based on the weight of the fluid, of a polyether polyol produced by mixing an active hydrogen compound with a double metal cyanide (DMC) catalyst in a reactor vessel, charging to the reactor vessel a mixture containing two or more alkylene oxides to activate the catalyst, and continuously feeding one or more alkylene oxides to produce the polyether polyol, wherein a 1% solution in water of the polyether polyol has a cloud point of from greater than about 32° C. to less than about 53° C., the polyether polyol has a number average equivalent weight of from greater than about 1,600 Da to about 10,000 Da, and a four-hour aerosol inhalation exposure to the polyether polyol has a LC50 of greater than about 5 mg/L. The water-miscible metalworking fluid produced by the inventive process may find use in cooling and/or lubricating metal surfaces during one or more of grinding, cutting, boring, drilling and turning of metal parts.