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.

Description

[0001] The present application is a continuation-in-part of, and claims the benefit of prior application Ser. No. 11 / 332,071, filed Jan. 13, 2006.FIELD OF THE INVENTION [0002] The present invention relates, in general to functional fluids, and more specifically to synthetic, water-miscible metalworking fluids (MWFs) which provide effective cooling and lubrication of metal surfaces at high speeds of operation in the grinding, cutting, boring, drilling, and / or turning of metal parts, while also reducing aerosol inhalation toxicity. BACKGROUND OF THE INVENTION [0003] Metalworking processes mechanically shape and work metallic articles or work pieces. Metalworking fluids (or metal removal fluids) are often used for the lubrication of metal cutting and forming tools. These fluids also provide cooling for the tool, facilitate the removal of cut chips or fragments from the tool-work piece interface, and help to provide an acceptable post-machining finished surface. Because metalworking flu...

AI Technical Summary

Problems solved by technology

However, one of the problems associated with the use of metalworking fluids results from the nature of the metalworking operations, i.e., a work piece rotates at a relatively high speed and both the work piece and a metalworking tool are lubricated by a metalworking fluid.

Oftentimes, these droplets are small enough to be classified as a mist which may pose a potential inhalation risk to the metal worker.

Although such suspected cancer-causing agents as alkali metal nitrites, chromates, and para-tert-butylbenzoic acid have been removed from water-based metalworking fluids, there still may be concerns regarding possible respiratory problems from the inhalation of aerosols generated from butanol-started polyether polyols that are the primary constituents of many synthetic, water-miscible metalworking fluids.

However, the branched polyether polyols of Pollmann et al. are sufficiently different in performance from current butanol-started compounds that reformulation of metalworking additive packages would be required and thus their ultimate performance may not be comparable.

However, Miller et al., are silent as to any risks associated with aerosol or mist exposure to their polyethers.

However, those random copolymers are marginally water soluble at slightly elevated temperatures with cloud points for 1% aqueous solutions being less than 30° C. Browne is also silent regarding potential risks associated with aerosol or mist exposure to his foam suppressants in metalworking applications.