| Water-miscible metal working fluids with reduced aerosol inhalation toxicity -> Monitor Keywords |
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Water-miscible metal working fluids with reduced aerosol inhalation toxicityRelated Patent Categories: Solid Anti-friction Devices, Materials Therefor, Lubricant Or Separant Compositions For Moving Solid Surfaces, And Miscellaneous Mineral Oil Compositions, Lubricants Or Separants For Moving Solid Surfaces And Miscellaneous Mineral Oil Compositions (e.g., Water Containing, Etc.), Organic Oxygen CompoundWater-miscible metal working fluids with reduced aerosol inhalation toxicity description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070167335, Water-miscible metal working fluids with reduced aerosol inhalation toxicity. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] 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 [0002] 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 fluids have the effect of reducing the cutting forces exerted on a tool and work piece, such fluids can significantly extend the life of the tool. [0003] 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. Under such conditions, the metalworking fluid is frequently thrown from the surface of the metal in the form of droplets. Oftentimes, these droplets are small enough to be classified as a mist which may pose a potential inhalation risk to the metal worker. [0004] In 1993, the United Automobile Aerospace and Agricultural Implement Workers of America (UAW) filed a petition requesting that the U.S. Dept. of Labor's Occupational Safety & Health Administration (OSHA) take regulatory action to protect workers from the potential risks of cancer and respiratory illness arising from exposure to metalworking fluids (MWFs). In response, OSHA convened the Metalworking Fluids Standard Advisory Committee in 1997 to ". . . advise the agency on appropriate actions to protect workers from the hazards associated with occupational exposure to MWFs". [0005] In 2001, OSHA issued the publication, "Metalworking Fluids: Safety and Health Best Practices Manual" to provide guidelines for reducing employee exposure to MWFs and to provide information on the health hazards of occupational exposure. This manual recommends that, ". . . the MWFs selected should be as non-irritating and non-sensitizing as possible. . . . Acute toxicity characteristics of metalworking fluids can be evaluated using information contained in ASTM Standard E-1302-00, Standard Guide for Acute animal Toxicity Testing of Water-Miscible Metalworking Fluids". [0006] To date, most industry efforts have focused on reducing worker exposure through engineering modifications or through the use of anti-misting aids. One such solution is exemplified by U.S. Pat. No. 6,344,517, issued to Quinn et al., which describes water-soluble or water-dispersible polymeric acrylate derivatives as additives for mist reduction and shear stability in metalworking formulations. [0007] 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. [0008] In a report by the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) entitled, "Technical Report No. 55--Pulmonary Toxicity of Polyalkylene Glycols" published in 1997, certain 50:50 ethylene oxide-propylene oxide (EO-PO) random copolymers initiated with butanol were identified as being toxic in aerosol inhalation studies with animals. No butanol-initiated EO-PO copolymers above a 1,000 equivalent weight met the limit test of an LC.sub.50 greater than 5 mg/L as described in ASTM Standard E-1302-00. For inhalation experiments, the concentration of the chemical in air that kills 50% of the test animals in a given time (typically four hours) is termed the LC.sub.50 value. As a general rule, the smaller the LC.sub.50 value, the higher the toxicity. The opposite also holds true, i.e., the larger the LC.sub.50 value, the lower the toxicity. [0009] Typically, water-miscible polyether polyols useful in metalworking fluids have been prepared by semi-batch processes involving the base-catalyzed anionic polymerization of alkylene oxides. As those skilled in the art are aware, in such processes an active hydrogen compound is charged to a reactor along with a basic catalyst, such as sodium or potassium hydroxide, the mixture is dehydrated, and an alkylene oxide or mixture of alkylene oxides is added to produce the polyether. Usually, these polyols are random copolymers prepared from butanol, ethylene oxide (EO), and propylene oxide (PO) and have been marketed under such trade names as the PLURASAFE WS fluid series (BASF Corp.) and the UCON HB fluid series (Dow Chemical Co.). [0010] One solution to the problem of aerosol toxicity for base-catalyzed polyols is disclosed by Pollmann et al., in U.S. Published Patent Application 2001/0031855 A1, where ethylene oxide-propylene oxide copolymers of higher functionality polyether polyols containing central branch points are shown to have LC.sub.50 values greater than about 5 mg/L. 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. [0011] As those skilled in the art are aware, double metal cyanide (DMC) catalysts have been used to prepare polyether polyols. These catalysts, which have a low tendency to promote isomerization of propylene oxide to allylic unsaturates and have faster rates of reaction, are prepared by the reaction of hexacyanometallate salts with transition metal salts in the presence of suitable organic ligands. [0012] An example of DMC catalyst utilization for the preparation of random copolymers of ethylene and propylene oxide can be found in EP 0992523 B1, issued to Miller et al., which describes a process for the activation or initiation of the catalyst with 100% propylene oxide prior to feeding a mixture of ethylene oxide and propylene oxide to make a monofunctional polyether for use in silicone surfactant production. However, Miller et al., are silent as to any risks associated with aerosol or mist exposure to their polyethers. [0013] Clement et al., in U.S. Pat. No. 6,642,423, teach that DMC catalysts are useful for the preparation of ethoxylates from starters which are sensitive to conventional basic or Lewis acid type catalysts. However, polyether polyols prepared in accordance with processes used in Clement et al., contain a pure block of ethylene oxide adjacent to the initiator molecule. Conversely, U.S. Published Patent Application 2005/0181967 A1 in the name of Ruland et al., discloses alkoxylates prepared from C.sub.10 alkanols in the presence of DMC catalysts where a pure propyleneoxy, buteneoxy, or penteneoxy block is attached to the initiator. [0014] Ruland et al., in U.S. Published Patent Application 2005/0215452 A1, also teach the use of DMC catalysts to prepare C.sub.10 alcohol-initiated polyether polyols with block or random copolymer structures but are silent with respect to the benefits of catalyst activation with an alkylene oxide mixture for reduced aerosol inhalation toxicity. [0015] Polyether polyols useful as foam suppressants can be made using DMC catalysts as described in U.S. Published Patent Application 2004/0091592 A1, in the name of Browne. However, those random copolymers are marginally water soluble at slightly elevated temperatures with cloud points for 1% aqueous solutions being less than 30.degree. C. Browne is also silent regarding potential risks associated with aerosol or mist exposure to his foam suppressants in metalworking applications. [0016] Sherman et al., in U.S. Published Patent Application 2005/0256014 A1, teach that EO-PO copolymer monols and diols with unsaturation levels below 0.01 meq/g exhibit low pulmonary toxicity. However, it is well-known by those skilled in the art that some of the lower equivalent weight base-catalyzed commercial products mentioned in the previously referenced ECETOC Technical Report 55 have low levels of unsaturation and low pulmonary toxicity. For example, Table 1 of the Report illustrates that typical values for unsaturation of 2,000 equivalent weight butanol-started monols are less than about one percent, which corresponds to less than about 0.005 meq/g of unsaturation. Sherman et al. also disclose the parallel addition of a monol or diol initiator along with the alkylene oxides. However, there still exists a desire to provide a detailed method for the production of higher equivalent weight polyols with acute aerosol inhalation LC.sub.50 values greater than about 3 mg/L for use in industrial applications where there is a potential for the production of mists or aerosols. [0017] Therefore, an improved process is needed for the production of water-miscible metalworking fluids that are less toxic with respect to aerosol inhalation exposure than are currently available commercial products. More importantly, a process for the production of polyether polyols for metalworking fluids that meet or exceed the limit test of an LC.sub.50 greater than 5 mg/L, as defined in ASTM Standard E-1302-00, at equivalent weights greater than about 1,000 Da would be very desirable. SUMMARY OF THE INVENTION [0018] The present invention provides such a process for producing a water-miscible metalworking fluid by combining 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 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 greater than about 32.degree. C., the equivalent weight of the polyether polyol is greater than about 1,000 Da, and a four-hour aerosol inhalation exposure to the polyether polyol has a LC.sub.50 of greater than about 0.50 mg/L. [0019] The process of the present invention may allow for the formulation and selection of less toxic metalworking fluids (MWFs) based on the inhalation test protocols referenced in the OSHA "Metalworking Fluids: Safety and Health Best Practices Manual". [0020] These and other advantages and benefits of the present invention will be apparent from the Detailed Description of the Invention herein below. DETAILED DESCRIPTION OF THE INVENTION Continue reading about Water-miscible metal working fluids with reduced aerosol inhalation toxicity... Full patent description for Water-miscible metal working fluids with reduced aerosol inhalation toxicity Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Water-miscible metal working fluids with reduced aerosol inhalation toxicity patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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