EP1028828A2

EP1028828A2 - Methods of working metal and compositions useful as working fluids therefor

Info

Publication number: EP1028828A2
Application number: EP98915449A
Authority: EP
Inventors: Dean S. Milbrath; Mark W. Grenfell
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1997-11-13
Filing date: 1998-04-09
Publication date: 2000-08-23
Also published as: CA2309170A1; JP2001523735A; WO1999025516A3; WO1999025516A2; AU6962998A

Abstract

Briefly, in one aspect, the present invention provides a method of working metals and ceramics comprising applying to the metal or ceramic workpiece, either prior to, during, or after working, an aqueous emulsion comprising a fluorocarbon fluid. In another aspect the invention provides aqueous emulsions comprising fluorocarbon fluids useful as cooling and lubricating fluids in the working of metals and ceramic materials.

Description

Methods of Working Metal and Compositions Useful As Working Fluids Therefor

FIELD OF THE INVENTION This invention relates to methods of working metal, including methods of forming and cutting metals. More particularly, the present invention relates to cooling and lubricating fluids used in conjunction with metal working operations.

BACKGROUND OF THE INVENTION Metalworking fluids long have been used in the cutting and abrasive working of metals. In such operations, including cutting, milling, drilling, and grinding, the purpose of the fluid is to lubricate, cool, and to remove fines, chips and other particulate waste from the working environment. In addition to cooling and lubricating, these fluids also can serve to prevent welding between a work piece and tool and can prevent excessively rapid tool wear. See Jean C. Childers, The Chemistry of Metalworking Fluids, in METAL- WORKING LUBRICANTS (Jerry P. Byers ed., 1994).

Metals may also be molded and shaped into a desired form by methods of forming that are similar in nature to the molding of pottery. Although many in number and widely varied in particular characteristic, methods of forming metal share the common, basic attribute of applying an external force to a metal to deform the metal without removing or otherwise cutting or abrading the metal to be shaped. For a detailed description of the basic metal forming methods see, for example, Betzalel Avitzur, Metal Forming, in 9 ENCYCLOPEDIA OF PHYSICAL SCIENCE AND TECHNOLOGY 651 -82 (1992).

A fluid ideally suited as a coolant or lubricant for metal and ceramic working operations must have a high degree of lubricity. Such a fluid also will possess the added advantage of being an efficient cooling medium that is environmentally non- persistent, is non-corrosive (i.e., is chemically inert), and such an ideal fluid also would leave minimal residue on both the working piece or the tool upon which it is used. Today's state of the art working fluids fall generally into two basic categories. A first class comprises oils and other organic chemicals that are derived principally from petroleum, animal, or plant substances. Such oils commonly are used either straight (i.e., without dilution with water) or are compounded with various polar or chemically active additives (e.g., sulfurized, chlorinated, or phosphated additives). They also are commonly solubilized to form oil-in- water emulsions. Widely used oils and oil-based substances include the following general classes of compounds: saturated and unsaturated aliphatic hydrocarbons such as n- decane, dodecane, turpentine oil, and pine oil; naphthalene hydrocarbons; polyoxyalkylenes such as polyethylene glycol; and aromatic hydrocarbons such as cymene. While these oils are widely available and are relatively inexpensive, their utility is significantly limited; because they are most often nonvolatile under the working conditions of a metalworking operation, they can leave residues on tools and working pieces, requiring additional processing at significant cost for residue removal.

A second class of working fluids for the working of metals and ceramics includes chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and perfluorocarbons (PFCs). Of these three groups of fluids, CFCs are the most useful and are historically the most widely employed, see, e.g., U.S. Pat. No. 3,129,182 (McLean), though PFCs have become a viable replacement in recent years for some metalworking applications, see, e.g., U.S. Pat. No. 5,676,005 (Balliett). Typically used CFCs include trichloromonofluoromethane, 1,1,2-trichloro- 1,2,2- trifluoroethane, 1, 1,2,2-tetrachlorodifluoroethane, tetrachloromonofluoroethane, and trichlorodifluoroethane. The most useful fluids of this second general class of metal working fluids (CFCs & HCFCs) possess more of the characteristics sought in a cooling fluid, and while they were initially believed to be environmentally benign, they are now known to be damaging to the environment; CFCs and HCFCs are linked to ozone depletion (see, e.g., P.S. Zurer, Looming Ban on Production of CFCs, Halons Spurs Switch to Substitutes, CHEM. & ENG'G NEWS, NOV. 15, 1993, at 12), and PFCs tend to persist in the environment (i.e., they are not chemically altered or degraded under ambient environmental conditions). SUMMARY OF THE INVENTION

Briefly, in one aspect, this invention provides a method of working metals and ceramics comprising applying to the metal or ceramic workpiece, either prior to, during, or after working, an aqueous emulsion comprising a fluorocarbon fluid. In another aspect the invention provides aqueous emulsions comprising fluorocarbon fluids useful as cooling and lubricating fluids in the working of metals and ceramic materials.

The aqueous emulsions of the invention possess a unique balance of properties that make them well-suited as working fluids for metals and ceramic materials. These emulsions leave minimal residue on the workpiece, are environmentally acceptable, and are more effective cooling media than most neat fluorinated fluids.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In their most essential aspect, the metal and ceramic working fluids described by this invention comprise an aqueous emulsion of at least one fluorocarbon fluid. Such fluorochemical emulsions include those where the liquid fluorocarbon comprises the dispersed phase as well as those where the liquid fluorocarbon comprises the continuous phase (and the water phase is discontinuous). The emulsions preferably will comprise a continuous phase and a discontinuous phase and will yield emulsions milky white in appearance. The emulsions of the invention are formed by use of one or more surfactants that are soluble in at least one phase of the emulsion and that comprise any of a broad class of surface-active compounds known to be useful as emulsifying agents.

Liquid fluorocarbons useful in the creation of the emulsions of the invention include any substantially fluorinated liquid compound. Thus, perfluorinated liquids, including perfluorinated hydrocarbons, perfluorinated ethers, and perfluorinated amines, partially fluorinated hydrocarbons, partially fluorinated amines, and partially fluorinated ethers all find utility in the practice of this invention. The most useful liquid fluorocarbons will be those that are suitably volatile at elevated temperatures such that they will evaporate from the surface of the subject metal or ceramic workpiece with relative ease. Such fluids will, therefore, be those having boiling points between about 30 °C and about 250 °C.

Useful perfluorinated liquids typically contain from 5 to 18 carbon atoms and may optionally contain one or more catenary heteroatoms, such as divalent oxygen or trivalent nitrogen atoms. The term "perfluorinated liquid" as used herein includes organic compounds in which all (or essentially all) of the hydrogen atoms are replaced with fluorine atoms. Representative perfluorinated liquids include cyclic and non-cyclic perfluoroalkanes, perfluoroamines, perfluoroethers, perfluorocycloamines, and any mixtures thereof. Specific representative perfluorinated liquids include the following: perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluoromethylcyclohexane, perfluorotributyl amine, perfluorotriamyl amine, perfluoro-N-methylmorpholine, perfluoro-N- ethylmorpholine, perfluoroisopropyl morpholine, perfluoro-N-methyl pyrrolidine, perfluoro- 1 ,2-bis(trifluoromethyl)hexafluorocyclobutane, perfluoro-2- butyltetrahydrofuran, perfluorotriethylamine, perfluorodibutyl ether, and mixtures of these and other perfluorinated liquids. Commercially available perfluorinated liquids that can be used in this invention include: Fluorinert™ FC™-43 Electronic Fluid, Fluorinert™ FC™-72 Electronic Fluid, Fluorinert™ FC™-77 Electronic Fluid, Fluorinert™ FC™-84 Electronic Fluid, Fluorinert™ FC™-87 Electronic Fluid, Performance Fluid™ PF-5060, Performance Fluid™ PF-5070, and Performance Fluid™ PF-5052. Some of these liquids are described in Fluorinert™ Electronic Fluids, product bulletin 98-0211-6086(212)NPI, issued 2/91, available from 3M Co., St. Paul, Minn. Other commercially available perfluorinated liquids that are considered useful in the present invention include perfluorinated liquids sold as Galden™ LS fluids, Krytox™ and Flutec™ PP fluids.

Partially fluorinated liquids also may be employed in the emulsions of the invention. Such liquids, like the above perfluorinated counterparts, typically contain from 5 to 18 carbon atoms and may optionally contain one or more catenary heteroatoms, such as divalent oxygen or trivalent nitrogen atoms. Useful partially fluorinated liquids include cyclic and non-cyclic fluorinated alkanes, amines, ethers, cycloamines, and any mixture or mixtures thereof.

A class of hydrofluorocarbon liquids particularly useful to form the emulsions of the invention comprise fluorinated ethers of the general formula: ( I )

(R_!-O)_n-R₂

where, in reference to Formula I, n is a number from 1 to 3 inclusive and Ri and R₂ are the same or are different from one another and are selected from the group consisting of substituted and unsubstituted alkyl, aryl, and alkylaryl groups and their derivatives. At least one of R] and R₂ contains at least one fluorine atom, and at least one of Ri and R₂ contains at least one hydrogen atom. Optionally, one or both of Ri and R₂ may contain one or more catenary or non-catenary heteroatoms, such as nitrogen, oxygen, or sulfur. Ri and R₂ may also optionally contain one or more functional groups, including carbonyl, carboxyl, thio, amino, amide, ester, ether, hydroxy, and mercaptan groups. Ri and R₂ may also be linear, branched, or cyclic, and may contain one or more unsaturated carbon-carbon bonds. Ri or R₂ or both of them optionally may contain one or more chlorine atoms provided that where such chlorine atoms are present there are at least two hydrogen atoms on the Ri or R₂ group on which they are present.

Preferably, the cooling and lubricating emulsions of the present invention are prepared with fluorinated ethers of the formula:

( H ) R_f-O-R

where, in reference to Formula II above, R_f and R are as defined for Ri and R₂ of Formula I, except that Rf contains at least one fluorine atom, and R contains no fluorine atoms. More preferably, R is an acyclic branched or straight chain alkyl group, such as methyl, ethyl, «-propyl, tso-propyl, w-butyl, t-butyl, or t-butyl, and Rf is preferably a fluorinated derivative of a cyclic or acyclic, branched or straight chain alkyl group having from 3 to about 14 carbon atoms, such as Λ.-C F9-, /-C-₁F9-, c-CόFπ-, or (/^'-C₃F₇)(w-C₃F₇)CF-. Rf may optionally contain one or more catenary or non-catenary heteroatoms, such as nitrogen, oxygen, or sulfur. R_f preferably is free of chlorine atoms, but in some preferred embodiments, R contains one or more chlorine atoms.

In the most preferred embodiments, Ri and R₂, or R_f and R, are chosen so that the compound has at least three carbon atoms, and the total number of hydrogen atoms in the compound is at most equal to the number of fluorine atoms. Compounds of this type tend to be nonflammable. Representative of this preferred class of hydrofluoroethers include C₃F₇OCH₃, C₃F₇OC₂H₅, C₄F₉OCH₃, C₄F₉OCH₂CI, C₄F₉OC₂H₅, c-C₇Fι₃OCH₃, c-C₇Fι₃OC₂H₅, C₇Fι₅OCH₃, O₇F₁₅OC₂H₅, CιoF₂iOCH₃, and C₁₀F₂₁OC₂H₅. Blends of one or more fluorinated ethers are also considered useful in practice of the invention. Any surface active emulsification agent that will create a stable emulsion of the fluorinated fluid may be employed to create an aqueous emulsion of the above fluorocarbons. Such surfactant compounds span many and diverse chemical classes and include many surfactants widely known and used in a variety of applications, including specifically those known as emulsifiers for fluorinated fluids. Useful emulsifiers may be nonionic, cationic, anionic or amphoteric in nature, though nonionic emulsifiers generally are preferred for most applications. Among the specific useful surface-active compounds are biochemical and other naturally occurring classes of emulsifiers including lipids, phospholipids, and lecithins, such as those described by U.S. Pat. Nos. 4,423,077 (Sloviter), 4,865,836 (Long, Jr.), and 5,061,484 (Heldebrbrant); fatty acids and tri-, di- and mono-glycerides of fatty acids, including those described by U.S. Pat. Nos. 3,962,439 and 4,713,459, both to Yokoyama et al.; as well as cholesterols, tocopherols, steroids, albumins, glycerols, dextrans, geletin, etc. Also useful are those myriad surface active compounds described as suitable for emulsification of fluorinated fluids by U.S. Pat. Nos. 5,011, 713 (Lenti et al.), 5,439,944 (Kaufman et al.), and 5,562,911 (Brunetta et al.), as well as those fluorinated emulsifiers described as useful for the same purpose by U.S. Pat. Nos. 3,989,843 (Chabert et al.), 4,987,154 (Long et al.), and 5,532,310 (Grenfell et al.), all the above descriptions of which are incorporated herein by reference.

Also useful as emulsification agents are those fluorinated surface-active compounds depicted generally by the formula:

(R yqyz), m

wherein n is 1 or 2, x is 0 or 1, m is 1 or 2, and RV is a fluorochemical group identical to that defined earlier for the fluorochemical treatment except that most preferably R'_f for the fluorochemical surfactant contains only from about 1 to about 12 carbon atoms. The composition of the fluorochemical surfactant should contain, relative to the amount of surfactant solids, at least 5 weight percent, preferably at least about 20 weight percent, of carbon-bound fluorine in the form of said Rf group or groups; Z is a water-solubilizing polar group containing an anionic, cationic, nonionic or amphoteric moiety or any combination thereof. Typical anionic Z groups include CO₂H, CO₂M, SO₃H, SO₃M, OSO₃H,

OSO₃M, OPO(OH)₂, and OPO(OM)₂, wherein M is a metallic ion, such as sodium, potassium or calcium, or is ammonium or another such nitrogen-based cation. Typical cationic Z groups include NH₂, NHR, wherein R is a lower alkyl group, and N '₃A', where R' is a lower alkyl group or hydrogen and A' is an anion such as chloride, iodide, sulfate, phosphate, or hydroxide. Representative nonionic Z groups include polyoxyethylenes (e.g., O(CH₂CH₂O)₇CH₃ and O(CH₂CH₂O)₁₄H), and mixed polyoxyethylene/polyoxypropylene alcohols and polyols. Typical amphoteric Z groups include N⁺(CH₃)₂O-, N⁺(CH₃)₂CH₂CH₂COO- and N⁺(CH₃)₂CH₂CH₂CH₂SO₃-; and Q is a multivalent, generally divalent, linking group such as an alkylene (e.g., ethylene), an arylene (e.g., phenylene), a combination of an alkylene and an arylene (e.g., xylylene), an oxydialkylene (e.g., CH₂CH₂OCH₂CH₂), a thiodialkylene (e.g., CH₂CH₂SCH₂CH₂), a sulfonamidoalkylene (e.g., SO₂N(CH₂CH₃)CH₂CH₂), a carbonamidoalkylene (e.g. ,

CONHCH₂CH₂CH₂), or a sulfonamidodialkylene (e.g., CH₂CH₂SO₂NHCH₂CH₂). The Q groups for a specific surfactant will depend upon the specific reactants used in its preparation. In some instances, more than one fluorochemical radical may be attached to Q and, in other instances, a single fluorochemical radical may be attached by a single linking group to more than one polar solubilizing group. For the particular case where x is 0, Q is absent and R'f is covalently bonded to Z which will often be the case when Z is SO₃M or CO M.

Surfactants corresponding to the above formula are described in U.S. Pat.

No. 2,915,554 to Olson, et al., the disclosure of which is incorporated herein by reference.

Many useful emulsification agents are available commercially. Commercially available nonionic surfactants include those sold under the PLURONIC tradename (block copolymer's of ethylene oxide and propylene oxide available from BASF Corp., Performance Chemicals), the BRIJ tradename (polyethoxylated straight chain alkanols available from ICI Americas, Inc.), the TERGITOL tradename (polyethoxylated branched chain alkanols available from Union Carbide Corp.), the TRITON and IGEPOL tradenames (polyethoxylated alkyl phenols available from Union Carbide Corp. and Rhone-Poulenc, North American Chemicals, Surfactants and Specialties, respectively) as well as the SURFYNOL tradename (acetylenic glycols available from Air Products and Chemicals, Inc.). Suitable nonionic and ionic surfactants are sold, for example, under the tradename FLUORAD by the 3M Company (fluorochemical carboxylic and sulfonic acid salts). The aqueous emulsions of the invention typically will comprise a minor amount of the chosen fluorinated liquid, though emulsions comprising more than 50 percent by volume of fluorinated liquid may also prove useful, and it will be understood that the particular composition of any chosen emulsion will be selected according to the particular needs of the metalworking process into which the emulsions are to be employed and that selection is well within the competence of the skilled artisan. The concentration of the emulsifier or emulsifiers within the emulsion will be that concentration required to create a stable aqueous emulsion of the fluorinated liquid. For the purposes of this invention, an emulsion is considered stable when a homogenous mixture is created that remains homogeneous for at least five to ten seconds, preferably for more than thirty seconds. It will be understood, however, that emulsions employed in metalworking applications typically are agitated continuously, and the length of time for the dispersion to separate without agitation serves here only as a relative measure of the quality of the emulsion and not as an absolute measure of its utility. Emulsions that remain dispersed with agitation but do not remain stable for long periods of time without agitation are nonetheless considered useful and within the scope of the present invention.

The precise concentration of the emulsifier will, of course, depend on the subject fluorinated fluid and upon the chosen emulsifier but typically will comprise between about 0.1 and about 10.0 percent by weight of the aqueous emulsion. It will be preferred to prepare the emulsion with the lowest operative concentration of emulsifier for the given emulsion to reduce the expense of the overall emulsion as well as to avoid leaving a significant residue of the emulsifier on the metal or ceramic workpiece. The fluorochemical emulsions of the invention also may contain additives to make the emulsion more useful in metalworking. Such materials include rust and corrosion inhibitors, lubricious materials, antioxidants, antibacterial agents, defoamers, dyes, freezing point depressants, pH buffers, etc. These additives may be soluble in either the continuous or discontinuous phase, and the selection of these additives for any given method of cutting, abrasive, or forming metal or ceramic working also is well known to the art and is well within the competence of the skilled artisan.

Suitable lubricious additives include one or more base oils or synthetic organic fluids that are soluble in the fluorochemical phase and that optimize the lubricating nature of the composition. The most useful additives are those that are volatile under the operating conditions of the metal or ceramic operation into which they are employed (with a boiling point <250°C). Useful lubricious additives include, for example: saturated and unsaturated aliphatic hydrocarbons such a n- decane, dodecane, turpentine oil and pine oil; naphthalenic or aromatic hydrocarbons such as naphtha and cymene; polyoxyalkylenes such as polyethylene glycols or polypropylene glycols; thiol esters and other sulfur containing compounds; and chlorinated hydrocarbons including oligomers of chlorotrifluoroethylene, chlorinated fluorocarbons, and other chlorine-containing compounds. Also useful for such purposes are load resistive additives which include phosphates, fatty acid esters, fluorochemical acid esters and amides, alkylene glycol ethers, and alkylene glycol ether esters. These classes of compounds include trialkyl phosphates, dialkyl hydrogen phosphates; methyl and ethyl esters of Cio to C₂o carboxylic acids; monoethers of mono-, di- and tri- ethylene or propylene glycols; ester's of monoethers of mono-, di- and tri- ethylene or propylene glycols; and the like. Representative load resistive additives include triethyl phosphate, dimethyl hydrogen phosphate, ethyl caproate, propylene glycol monobutyl ether, and propylene glycol monoethyl ether acetate.

One or more partially fluorinated or perfluorinated additives also may be added to the fluorochemical emulsions to f rther optimize the lubricious properties of the composition. Such additives typically comprise one or more perfluoroalkyl groups coupled to one for more hydrocarbon groups through a functional moiety. Suitable perfluoroalkyl groups consist of straight-chain and branched, saturated and unsaturated C -Cι₂ groups, and useful hydrocarbon groups include straight-chain and branched, saturated and unsaturated Cio to C₃₀ groups. Suitable functional linking moieties can be groups comprising one or more heteroatoms such as O, N, S, P or functional groups such as -CO₂-, -C(O)-, -C(O)NR-, SO₂-, -SO₃-, -SO₂NR, -PO₄-, -PO₃-, -PO₂(R)-, or -POR.R₂- where R, R and R₂ are hydrogen or short chain alkyl groups. In addition, perfluoroalkyl groups coupled to -CH₂OH, - CH(OH)OH, -CH₂NH₂, and -CO M where M is H or an suitable cation such as NH₄ ⁺ are particularly useful. Fully fluorinated additives such as polyperfluoroethers with and without functional end groups (-OH, -CO₂R, -CH₂OH, etc.) also can be used to increase the lubricious properties of the emulsion formulations.

While not wishing to be bound to any specific emulsion formulation or preparative method, fluorochemical emulsions generally are formulated with a combination of surfactants, typically where at least one of the surfactants is soluble in the aqueous phase and at least one in the fluorochemical phase. The surfactants most useful in the fluorochemical phase are nonionic and contain a highly fluorinated group such as a perfluoroalkyl (C_nF_2n+ι)-, a polyperfluoroalkoxy [H(OCF₂CF₂)„]- or H(OCF₂OC₂F₄)_n- or H[OCF₂CF(CF₃)]_n-, perfluorosulfonamide (C„F_2n+1SO₂NR)-, trihydroperfluoroalkoxy (HC_nF_2n+ι CH₂0)- or the like. Suitable water soluble surfactants can be nonionic, anionic, or cationic, and preferably have an HLB (hydrophilic/lipophilic balance) of 12 or less. Representative of this latter group are polyethoxylated phenols, polyethoxylated alkanols, and polyethylene oxide/propylene oxide block copolymers. Anionic surfactants can be salts of fatty acids, alkyl sulfonic acids, and the like. The aqueous phase of the emulsions can also optionally contain additives such as defoamers, corrosion inhibitors, and stabilizers. A buffer salt also can be dissolved in the water phase to maintain pH. The fluorochemical phase can optionally contain lubricious additives, dyes, corrosion inhibitors, or load resistive additives. To prepare the emulsions the water and fluorochemical phases generally are mixed to form a crude dispersion by physically shaking or vigorous mechanical agitation in a stirring vortexing, or mixing apparatus. This crude mixture can then be finished with higher shear methods such as homogenation in a Microfluidizer, ultrasonicator, or French press. In a metalworking operation the fluorochemical emulsions of the invention can be applied in the manner of conventional metalworking fluids. This would include flooding, spraying, submersion, etc. of the workpiece while the tooling cuts, forms or bends the desired shapes.

The emulsions of the invention may be utilized as working fluids in any process involving the cutting or abrasive treatment of metals or ceramic materials or in any process involving the forming or other deformative working of any metal suitable to such operations. The most common, representative, processes involving the cutting, separation, or abrasive machining of metals include drilling, cutting, punching, milling, turning, boring, planing, broaching, reaming, sawing, polishing, grinding, tapping, trepanning and the like. The most common, representative, processes involving the forming metals include: bulk deformation processes such as forging, rolling, rod, wire, and tube drawing, thread forming, extrusion, cold heading, and the like; and secondary metal forming processes such as deep drawing, stretch forming, knurling, spinning, shearing, punching, coining, and the like.

Metals commonly subjected to cutting and abrasive working and forming processes include: refractory metals such as tantalum, niobium, molybdenum, vanadium, tungsten, hafnium, rhenium, titanium; precious metals such as silver, gold, and platinum; high temperature metals such as nickel and titanium alloys and nickel chromes; and other metals including magnesium, bismuth, aluminum, copper, steel (including stainless steels), brass, bronze, and other metal alloys. The use of aqueous emulsions of a fluorocarbon fluid in such operations acts to cool the machining environment (i.e., the surface interface between a workpiece and a machining tool) by removing heat and particulate matter therefrom, and also lubricate machining surfaces to provide a smooth and substantially residue-free machined metal surface. In many forming/deformation operations their use can also eliminate the necessity of annealing.

EXAMPLES

Emulsion Preparation

For each of the following Examples the emulsions were prepared by combining the fluorinated compound, the surfactant, water and other additives in the proportions detailed below and shaking vigorously for several minutes. The crude suspension was then processed with a Microfluidizer™ Model 110-T in a recycle mode where the processed emulsion was returned to the reservoir continuously for 15 minutes. Each emulsion was then tested as described below. The prepared emulsions: Emulsion 1 : 100 mL of C F9OCH₃ with 0.1 wt%

C₈F₁₇SO₂N(C₂H₅)(CH₂CH₂O)_nCH₃, n=7-8, prepared as described in US 2915554), 400 mL of water with 0.1 wt% Brij 78™ (available from ICI America) and 0.01 wt% Antifoam A™ (available from Dow Corning) to produce a 20 vol.% aqueous emulsion. Emulsion 2: 200 mL of C4F9OCH₃ with 0.1 wt%

C₈F₁₇SO₂N(C₂H₅)(CH₂CH₂O)_nCH₃, 300 mL of water with 0.1 wt% Brij 78™ and 0.01 wt% Antifoam A™ to produce a 40 vol.% aqueous emulsion.

Emulsion 3: 100 mL of C₇F₁₅OCH₃ with 0.1 wt% C₈F₁₇SO₂N(C₂H₅)(CH₂CH₂O)„CH₃, 400 mL of water with 0.1 wt%

Brij 78™ and 0.01 wt% Antifoam A™ to form a 20 vol% aqueous emulsion.

Emulsion 4: 100 mL of (CJ^N, with 0.1 wt%

C₈F₁₇SO₂N(C₂H₅)(CH₂CH₂O)„CH₃,400 mL of water with 0.1 wt% Brij 78™ and 0.01 wt% Antifoam A™ to form a 20 vol% aqueous emulsion.

Emulsion 5: 100 mL of C-tF₉OCH₃ with 10 wt% dipropylene glycol di-n-propyl ether.and 0.1 wt% C₈F₁₇SO₂N(C₂H₅)(CH₂CH₂O)„CH₃, 400 mL of water with 0.1 wt% Brij 78™ and 0.01 wt% Antifoam A™ to form a

20 vol% aqueous emulsion. Examples 1 to 9

Aqueous emulsions of hydrofluoroethers and perfluoroamines (Examples 1 to 5) were tested by drilling 1/2" diameter holes in a 3/4" thick piece of type 304 stainless steel at a speed of 420 rpm or 55 surface feet per minute (SFM) at a feed of 3"/minute using a 0.25" peck program on an Mitsuura MC-600VF CNC drilling machine. The drill bit was a 2-flute high speed steel (HSS) twist bit (CLE-Forge). Three through holes were drilled using each coolant lubricant emulsion which was applied from a plastic squeeze bottle at a flow rate of about 40-45 mL/minute. The Comparative Examples made use of neat hydrofluoroethers (Comparative Examples 1 and 2), neat (C₄F9)₃N (Comparative Example 3), and a conventional water-based coolant lubricant, Cimtech™ 3900, an aqueous hydrocarbon emulsion available from Cincinnati Milacron (Comparative Example 4). In Comparative Example 4, the same experimental procedure was followed using an Excel 510 CNC drilling machine. The drill bit was stopped between holes and the temperatures of the drill bit and the workpiece (in the hole) were determined with a type K thermocouple fitted to an Omega (Model H23) meter. A new drill bit was used for each coolant lubricant tested. The work piece was then cleaned and the surface finish or roughness of each hole was measured using a Hommel T500 profilometer. Two passes each of 0.5" length were made on each hole, rotating the workpiece 90° between passes, and these were averaged over the three holes drilled to determine R, and R_3z. Data for each of the coolant lubricants tested are presented in Table 1. The numbers in parentheticals represent the standard deviation for each measurement.

Table 1

The emulsion preparations (Examples 1 to 5) all were more effective in cooling the drill bit and hole than the corresponding neat fluorochemical fluid (Comparative Examples 1 to 3). These values are also about the same as or slightly cooler than that found with a commercial water based coolant, Cimtech 3900 (Comparative Example 4). Surface roughness values were similar regardless of the formulation of the fluid (either neat or emulsified) and about the same as the commercial water based coolant.

Examples 6 to 10 and Comparative Examples 5-8

These examples show hydrofluoroether and perfluorocarbon emulsions can act as effective coolant lubricant fluids when used in the formation of threads in titanium with a cold forming bit. Holes were drilled in a 3/4" thick titanium block in rows spaced 1 1/2" apart with an 8.8 mm HSS bit using a conventional water based coolant (Cimtech 3900) on a Mitsuura MC-600VF CNC drilling machine. After cleaning and drying the workpiece, these holes were threaded using a 3/8-16 bit (Chromflo GH 8 HSS) run at 10 SFM. Emulsified hydrofluoroethers (Examples 6 to 8), perfluoroamines (Example 9), and an emulsified mixture of 10 wt % dipropyleneglycol «-propyl ether in C-tF₉OCH₃ (Example 10) were applied to the bit and the hole from a plastic squeeze bottle at a flow rate of about 40-45 mL/minute. Comparative Examples 5 to 7 made use of the neat hydrofluoroethers and perfluorocarbon fluids and Comparative Example 8 utilized a conventional tapping fluid, Molydee™ (available from Castrol). A new threading bit was used for each fluid tested.

Immediately after the bit was withdrawn from the workpiece its temperature and that of the threaded hole were measured with a type K thermocouple on an Omega Model HH23 meter applied to the bit tip and the hole thread, respectively. These temperatures were recorded and averaged over three separate test threads. Maximum load values as indicated on the CNC were also recorded and averaged. This data are presented in Table 2. The numbers in parentheticals represent the standard deviation for each measurement.

Table 2

The tap and work piece material temperatures found for Examples 6 to 10

(fluorochemical emulsion coolant lubricants) were significantly lower than when the neat fluids were applied (Comparative Examples 5 to 8). The commercial tapping fluid Molydee™ produced a significantly higher tap temperature along with significant amounts of smoke. The Molydee™ tap additionally had a large amount of charred residue while the taps from the test emulsions of fluorochemical fluids were clean with no residue. The machine load factors observed for emulsified fluorochemicals appear to be either unchanged or slightly higher than those found with the neat fluorochemicals.

Claims

CLAIMSWe claim:

1. A method of working metals and ceramics comprising applying to a metal or ceramic workpiece an aqueous emulsion comprising a fluorocarbon.

2. The method of claim 1 wherein said application is made prior to or during the working of said metal or ceramic workpiece.

3. The method of claim 1 or 2 wherein the fluorocarbon comprises the continuous phase of said emulsion.

4. The method of claim 1 or 2 wherein the aqueous phase comprises the continuous phase of said emulsion.

5. The method according to any one of claims 1-5 wherein said working comprises cutting or abrasive treatment of said metal or ceramic workpiece.

6. The method according to any one of claims 1-5 wherein said working comprises deformation of a metal workpiece.

7. The method according to any one of the preceding claims wherein said fluorocarbon is a perfluorocarbon or is a hydrofluoroether.

8. The method of claim 7 wherein said fluorocarbon is a perfluorocarbon selected from the group consisting of : perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluoromethylcyclohexane, perfluorotripropyl amine, perfluorotributyl amine, perfluorotriamyl amine, perfluorotrihexyl amine, perfluoro-N-methylmorpholine, perfluoro-N-ethylmorpholine, perfluoro-N- isopropyl morpholine, perfluoro-N-methyl pyrrolidine, perfluoro-1,2- bis(trifluoromethyl)hexafluorocyclobutane, perfluoro-2-butyltetrahydrofuran, perfluorotriethylamine, and perfluorodibutyl ether.

9. The method of claim 7 wherein said fluorocarbon is a hydrofluoroether selected from the group consisting of: C₃F OCH₃, C₃F₇OC2H₅, C₄F₉OCH₃,

C₄F₉OCH₂Cl, C₄F₉OC₂H₅, C-C₇F₁₃OCH₃, c-C₇F╬╣₃OC₂H₅, C7F1₅OCH3, C₇F₁₅OC₂H₅, C₁₀F₂₁OCH₃, and C╬╣₀F₂╬╣OC₂H₅.

10. The method according to any one of the preceding claims wherein said emulsion further comprises lubricious additive selected from the group consisting of: saturated and unsaturated aliphatic hydrocarbons; naphthalene hydrocarbons; polyoxyalkylenes; aromatic hydrocarbons; thiol esters; oligomers of chlorotrifluoroethylene; chlorinated hydrocarbons; chlorinated perfluorocarbons; phosphates; fatty acid esters; alkylene glycol esters; and fluorinated alkylated compounds comprising one or more perfluoroalkyl groups coupled to one or more hydrocarbon groups through a functional moiety.