US3374171A - Aqueous lubricant compositions containing an alkanolamine, a saturated organic acid and a polyoxyalkylene glycol - Google Patents

Description

United States Patent 3,374,171 AQUEOUS LUBRIC NT COMPOSITIONS CON- TAINING AN ALKANOLAMINE, A SATU- RATED ORGANIC ACID AND A POLYOXY- ALKYLENE GLYCOL Robert H. Davis, Pitman, N.J., assignor to Mobil Oil Corporation, a corporation of New York No Drawing. Continuation-impart of application Ser. N 505,454, Oct. 28, 1965. This application Apr. 25, 1967, Ser. No. 633,416

Claims. (Cl. 252-343) ABSTRACT OF THE DISCLOSURE Lubricant compositions are provided containing a major proportion of water and minor amounts of a watersoluble alkanolamine, a saturated organic acid having from about 6 to about 9 carbon atoms per molecule and a polyoxyalkylene glycol. These compositions are particularly effective as cutting fluids in metal machining operations.

CROSS REFERENCES TO RELATED APPLICATIONS- Parent applications: Application Ser. No. 505,454, filed Oct. 28, 1965, now abandoned. Application Ser. No. 569,- 598, filed Aug. 2, 1966, and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the invention This application, which is a continuation-impart of my application Ser. No. 505,454, filed Oct. 28, 1965, now abandoned, and a continuati-on-in-part of my copending application Ser. No. 569,598, filed Aug. 2, 1966, and now abandoned, relates to lubricant compositions and, more particularly, to aqueous compositions adapted for use as lubricants and coolants in metal machining operations.

2. Description of the prior art In machining operations of metals, such as cutting, grinding, turning, milling and the like, it is customary to flood the tool and the work with a coolant for the purpose of carrying off heat which is produced during the operation. It is also customary to employ these coolants in combination with various agents having lubricating and extreme-pressure properties for reducing friction between the tool and work piece, particularly in operations such as tapping and broaching. In this respect, it has, heretofore,

been the practice to employ for such purpose aqueous compositions containing such lubricating agents as emulsified petroleum or non-petroleum additives. Such aqueous cutting fluids, in order to perform satisfactorily, should meet certain important requirements.

Among the requirements for a satisfactory cutting fluid are corrosion-inhibiting properties for ferrous and cuprous alloys, and also stability under the conditions of operation. While various cutting fluids may possess such characteristics, there are, however, further important requirements that should also be met. Among these requirements is the ability to avoid leaving deposits on the tool and the work following the machining operation which result from subsequent drying of the fluid and which are difli cult to remove. Other important requirements include tolerance in hard water solutions so that the precipitation of lubricant components will not occur, avoidance of tacky residues which interfere with the operation of the machine and avoidance of excessive foam formation. Cutting fluids known prior to this invention have not, however, satisfactorily met all of the foregoing requirements.

Summary of the invention It has now been found that a balanced formulation can be obtained in a lubricant composition which is effective as a cutting fluid having improved corrosion-resistant lubricating and cooling efficiency properties and which, in the course of machining operations, maintains its transparency in hard water solutions, avoids the formation of tacky water-insoluble residues, is free from excessive foam formation and is resistant to rancidity.

The foregoing improvements, as more fully hereinafter, described, are, in general, realized with aqueous compo-I sitions comprising a balanced formulation and containing as essential components a major proportion of water and, in individual min-or proportions, the combination of a saturated organic acid, either straight-chain or branchedchain having from about 6 to about 9 carbon atoms per molecule, a water-soluble alkanolamine and a water-soluble polyoxyalkylene glycol. In this respect, it is found that the alkanolamine component, in addition to function-: ing as a corrosion-inhibiting agent in which the aforementioned organic acids are soluble, also functions as a plasticizer in that, in the course of use, evaporation of water from the cutting fluid leaves a residue upon machinery parts which is desirably soft or semi-liquid. The function of the organic acid component in combination with the alkanolamine is primarily that of a corrosion inhibitor in that it forms the corresponding amine acid salt. The water-soluble polyoxya-lkyl-ene glycol in the novel com,- position functions as a load-support agent.

The water-soluble alkanolamine employed in the novel formulation may be of any molecular weight but should,' preferably, be liquid at room temperature. The lower molecular weight compounds are generally preferred and, for this purpose, it has been found that such allcanolamines as mono-, dior tri-eth-an-olamine are most eflec.. tive. Other water-soluble alkanolamines may also be em ployed, and include such alkanolamines as is-o-propanolamines, e.g., mono-, diand tri-isopropanolamine, di-, methyl-ethanolarnine, diethyl-e-thanolamine, aminoethyl ethanol-amine, N-acetyl et-hanolamine, phenylethanolamine, phenyldiethanolamine and mixtures thereof.

The organic acid component, as previously indicated, comprises a saturated organic acid, either straight-chain or branched-chain having from about 6 to about 9' carbon atoms per molecule, or mixtures thereof. In this respect, it has been found that the relatively lower molecular weight acids having from about 1 to about 5 carbon atoms per molecule do not satisfactorily function as rust in-. hibitors and are also objectionable because of their strong odor. On the other hand, it is found that by employing relatively high molecular weight saturated organic acids, i.e., acids having more than about 9 carbon atoms per. molecule, there results poor hard water stability, reduced corrosion inhibiting properties and high foaming tenden cies. Of particular utility with respect to the aforementioned saturated intermediate molecular weight organic acids in the present improved formulation are hexanoic,. heptanoic, .caprylic and pelargonic acids.

In combination with the aforementioned water-soluble alkanolamines 'and saturated organic acids is the use of the water-soluble polyoxyalkylene glycols as loadsupport agents. Preferred compounds of this type include. water-soluble oils obtained by copolymerizing mixtures of ethylene oxide and propylene oxide, e.g., oils prepared by copolymerizin-g a 50-50 mixture of ethylene, oxide and propylene oxide; water-soluble heteric co-f polymeric alkylene glycols, ethers or esters thereof,. wherein the different oxyalkylene units 'are substantially,] randomly distributed throughout the eritire polyoxy alkylene chain; water-soluble polyoxylalkylene compounds containing hydrophobic homopolyoxyalkylene 3 units; and polymeric agents, in general, which are block copolymers of cogeneric mixtures of conjugated polyoxyalkylene compounds containing at least one hydrophobic homopolyoxyalkylene unit, having a unit weight of at least about 800, and one or two other hydrophilic polymeric units which comprise from about percent to about 90 percent of the total polymeric compound. The most desirable water-soluble polyoxyalkylene glycols for use in the formulations of the present invention comprise the polyether polyols produced by reacting ethylene oxide and propylene oxide having hydroxyl numbers from about 22 to about 38. If so desired, in orded to impart increased anti-rust properties to the aqueous lubricant composition, an alkali metal nitrite may also be employed in the novel formulation. In this respect, it is found that more specific increased resistance to copper corrosion may also be obtained by the additional use of the sodium salt of mercapto-benzothiazole or benzotriazole.

The aforementioned novel formulations of water-soluble al'kanolamine, saturated organic acid and water-soluble polyoxyalkylene glycol may also include a wide variety of germicidal agents for inhibiting bacterial growth. For this purpose, the germicidal agent may comprise, for example, a halogenated cresol, either completely or partially halogenated, and may include such representative compounds as completely or partially chlorinated, brominated, fluorinated or iodated cresols. Typical examples of this class of materials include: chloro-, dichloro-, trichloro-, and tetrachlorocresols; bromo-, dibromo-, tribromo, and tetrabromocresols, or any of the aforementioned compounds in which the chlorine or bromine atoms are substituted in whole or in part by fluorine or iodine. More specific compounds include: para-chlorometa-cresol; para-bromo-meta-cresol; para-fluoro-metacresol; para-iodo-meta cresol; 2,4-dichloro-meta-cresol; 2,4,5 trichloro meta-cresol; 2,4,5,6-tetrachloro-metacresol; 2,4 dibromo-meta-cresol; 2,4,5-tribromo-metacresol; 2,4,5,6 tetrabromo-meta-cresol; or any of the aforementioned compounds in which the chlorine or bromine atoms are substituted in whole or in part by fluorine or iodine; or any corresponding ortho or paracresols of the aforementioned compounds substituted for the corresponding meta-cresols.

' Other germicidal agents that may be employed in the above-described novel formulations may include microbicidal gases, for example, in the form of aldehydes, such as formaldehyde, or aldehyde-releasing agents, such as formaldehyde-releasing agents, i.e., materials which breakdown in storage to form the aldehyde or aldehyde compounds as decomposition products. Thus, it is found that compounds of the type such as tris(hydroxymethyl)nitromethane are particularly effective in releasing formaldehyde and thereby providing germicidal protection over relatively long periods of time. Other microbicidal gases that may be employed for this purpose include ethylene oxide and beta propiolactone. Alcohols such as methyl alcohol, ethyl alcohol or higher alcohols may also be employed as germicidal agents. Other effective germicidal agents include halogens and halogen compounds, particularly iodine and chlorine and compounds of these halogens. Specific compounds of this type may include chloride of lime and iodophors. Furthermore, as germicidal agents, compounds of heavy metals may also be employed in the novel formulations. These may include such compounds as bichloride of mercury and organic mecurials such as lMercurochrome, Merthiolate, Metaphen, silver nitrate and copper sulfate. Germicidal'agents comprising phenol and its derivatives ma also be employed in the novel formulations, which include the aforementioned cresols and bis-phenols. Synthetic detergents may also be employed as germicidal agents, which are of the non-phenolic type. These may include, for example, ammonium halides, such as ammonium chloride, in which the hydrogen atoms have been replaced by organic radicals; particularly effective are quaternary compounds in which the long-chain organic radical (alkyl group) contains from 12 to 16 carbon atoms. Other materials include quaternary compounds in which the organic group is an anion, e.g., sodium lauryl-sulfate, as well as these compounds which do not ionize.

The novel lubricant compositions of the present invention, as previously indicated, are formulated in accordance with certain balanced proportions expressed in weight percent. Thus, with water being present in a major proportion in each instance, the alkanolamine is employed in an amount from about 5 to about 40 percent, and preferably in an amount from about 20 to about 35 percent, by Weight. The organic acid component is employed in an amount from about 0.1 to about 9 percent, and preferably in an amount from about 1 to about 4 percent, by weight. The polyoxyalkylene glycol is employed in an amount from about 0.5 to about 20 percent, and preferably in an amount from about 0.5 to about 5 percent, by weight. Where a germicidal agent is also to be incorporated in the novel formulation, these agents are employed in an amount from about 0.05 to about 5 percent, and preferably in an amount from about 0.5 to about 3 percent, by weight. When the alkali metal nitrite is to be included in the formulation, it is generally employed in an amount from about 0.1 to about 10 percent, and preferably in an amount from about 0.1 to about 5 percent, by Weight. When the sodium salt of mercapto-benzothiazole is to be included in the formulation, it is generally present in an amount from about 0.1 to about 6 percent, and preferably from about 0.1 to about 3 percent, by weight. If so desired, other additives for enhancing rust protection or for the purpose of raising the pH of the system may be employed. Such additional additives may include boric acid or oxides of boron for enhancing rust protection, and are generally employed in an amount from about 0.1 to about 5 percent, and preferably from about 0.1 to about 3 percent, by weight. For raising the pH of the system, such additional additives may be employed in the form of alkali metal hydroxides, including, more specifically, sodium, lithium or potassium hydroxide. When the latter are present, they are generally employed in an amount from about 0.1 to about 3 percent, and preferably from about 0.1 to about 1.5 percent, by weight. Furthermore, if so desired, various water-soluble chelating agents may be employed to soften the Water vehicle. These may include, for example, salts of ethylenediamine tetraacetic acid, nitrilo-triacetic acid or diethylene triamine pentaacetic acid. When any of the aforementioned chelating agents are employed, they are generally present in an amount from about 0.1 to about 5 percent, by weight. In each instance, of course, it will be apparent that sufficient water is employed in order to balance the formulation.

The novel lubricant compositions of the present invention are preferably prepared by a blending procedure which comprises reacting the alkanolamine and organic acid components with about 10 to about 20 parts of water, which is to be present in the finished formulation. This blending procedure may be carried out at room temperature. However, heating to F. with agitation is most satisfactory. The remaining quantity of Water required to be present in the finished product is added, together with the polyoxyalkylene glycol, and any of the aforementioned other desired components. It should be noted, however, that if an alkali metal nitrite is to be present in the finished product, such material is added last for the reason that addition of acids such as caprylic acid to a solution of sodium nitrite could result in decomposition of the nitrite, thus reducing or nullifying'its rust-inhibiting effects. If a germicidal agent is to be incorporated in the novel formulation, it is preferably. blended with the alkanolamine and organic acid.

5 DESCRIPTION OF SPECIFIC EMBODIMENTS The compounding of the novel compositions of the present invention may be illustrated by the preparation of lubricant and cutting fluids from the formulations in the following tables and examples and which also include comparative data and the observations noted when compositions are prepared which do not include all of the essential saturated organic acid, alkanolamine and polyoxyalkylene glycol components of the present improved formulations. In this respect, as indicated above, among the outstanding properties of the improved lubricant compositions of the present invention are their rust-inhibiting properties, hard water stability and high machining efficiency. Accordingly, these improved compositions were subjected for the purpose of evaluation to the following corrosion, hard water stability and machining efficiency tests:

Corrosion test One to three grams of malleable iron turnings are placed in a glass container, washed with the test solution which is to be evaluated, drained and allowed to stand in an atmosphere of approximately 90 percent relative humidity and at a temperature of about 70 F. for a period of about 72 hours. After this period the sample is then checked for the appearance of rust. The samples are graded from (no rust) to 3 (severe rusting) in accordance with the following standard chart. This test, and a more detailed general method for carrying it out is described in Patent No. 3,071,545, issued Jan. 1, 1963.

Description: Rating No rusting, or less than 1% of the metal surface coated with yellow iron oxide 0 the specimen 2 Severe rusting, rusting covering more than of the surface of the specimen 3 cant compositions of the present invention is evaluated with respect to a series of holes, drilled in a test bar made from hot-rolled steel, which are to be tapped. Prior to testing, samples of the novel formulations are diluted by employing 1 part, by weight, of the additive concentrate to 5 parts, by weight, of distilled water. The fluid is applied to the tap with a polyethylene squeeze-bottle. Four unknown samples are bracketed by two standards. The tapping efficiency is calculated by dividing the torque obtained with the unknown, into the average standard torque, and multiplying by 1-00. This test, and a more detailed general method for carrying it out is described in Patent No. 3,071,545, issued Jan. 1, 1963.

In the following Table I, samples containing triethanolamine, a polyether polyol, in the form of a copolymer, produced .by reacting ethylene oxide and propylene oxide, and having a hydroxyl number from about 22 to about 3 8, and a saturated organic acid having from 4 to 9 carbon atoms per molecule, were subjected to the aforementioned corrosion test, in which the composition of the hard water employed was derived from that described in ASTM Test 147857T, paragraph 4a, which shows a preponderance of magnesium and sulfate ions. This water was modified in two ways, viz., the active ingredients were increased by per cent, in order to increase total hardness from about 230 p.p.m. to about 345 p.p.m. and to increase the sulfate content to about 270 p.p.m. Sodium hydroxide was used to neutralize excess carbon dioxide employed for stabilization to attain a neutral pH.

As will be seen from Table I the samples containing triethanolamine, the ethylene oxide-propylene oxide c0- polymer, and either hexanoic, hept-anoic, caprylic or pelargonic acids (Examples 3, 4, 5, and 6) eifectively inhibited rusting of the malleable iron turnings, with a rating, in each instance, of 0. On the other hand, where the acid component comprised valeric or isobutyric acids, (Examples 1 and 2), severe rusting occurred with a rating of 3, clearly indicative of the fact that when the acid component contains less than 6 carbon atoms per molecule, it is unsatisfactory for use in metal working operations.

TABLE I.-AQUEOUS SYSTEMS CONTAINING AN ALKANOLAMINE SALT OE SATURATED CrC ORGANIC ACID AND ETHYLENE OXIDE-PROPYLENE OXIDE COPOLYMER Base Formula Malleable Iron Distilled Rust-Test Ex. No. Triethanol- Isobutyric Valerie Hcxanoic I-Ieptanoic Caprylic Pelargonic Copolymer Water amino 0' Acid Ac 0' Acid Acid (Percent (Percent 1 part base formula (Percent (Percent (Percent (Percent (Percent (Percent (Percent Wt.) Wt.) to 5 parts ASTM Wt.) Wt.) Wt.) Wt.) Wt.) Wt.) Wt.) Hard Water Hard water stability test Machining efliciency test The machining efiiciency of the novel improved lubri- In the following Table II, samples containing triethanolamine, a copolymer of ethylene oxide and propylene oxide, as recited in Table I, and a saturated organic acid having from 6 to 10 carbon atoms per molecule, were subjected to a hard water stability test, which was carried out in the following manner: One part of the specific aqueous metal working fluid was mixed with five parts of the AS'IM hard water, as described in Table I, and stored in a ml. graduate cylinder for a period of 72 hours and at a temperature from about 70 F. to about 75 F. At the end of this period, the volume of sediment formed as a result of interaction between the additives in the cutting fluid and polyvalent ions present in the water, were recorded.

As will be seen from Table II, the samples containing In order to illustrate the eflicacy and criticality of emtriethanolamine, the ethylene oxide-propylene oxide coploying a germicidal agent, such as a halogenated cresol, polymer, and either hexanoic, heptanoic, caprylic or in the lubricating compositions of the present invention in pelargonic acids (Examples 1, 2, 3, and 4), revealed no combination with the aforementioned alkanolamine, orseparation after 72 hours. On the other hand, Where the ganic acid and polyoxyalkylene glycol components, a acid component comprised capric acid (Example 5), a series of comparative tests Were conducted in which the white insoluble soap by volume) appeared at the aforementioned halogenated cresol, as represented by top of the graduate. This outstanding difference, with para-chloro-meta-cresol, and also other related germicidal reference to saturated organic acids having more than 9 agents, were evaluated for their effect in inhibiting baccarbon atoms per molecule, is indicative of the fact that 10 terial growth in the otherwise identical lubricating comthe use of such higher organic acids can result in clogged position. filters, poor rust protection and reduced tool life in areas The test employed for the aforementioned purpose is a where hard Water is encountered. biocide screening test employing a shaker method and, in

. ABLE II.AQUEOUS SYSTEMS CONTAINING AN ALKANOLAMINE SALT OF SATURATED Co-Gio ORGANIC ACID AND EII'IYLENE OXIDE-PRO PYLEN E OXIDE COPOLYMER Base Formula Hard Water Stability Test Distilled Ex. No. Trietha- Hexanoic Heptanoic Caprylie Pelargonie Capric Copoly- Water Percent Volume Separation nolamine Acid Acid Acid Acid Acid mer (percent 1 part base formula to 5 parts (Percent (Percent (Percent (Percent (Percent (Percent (Percent t.) ASTM Hard Water VVt'.) Wt.) \Vt.) W't.) Wt.) 'Wt.)

7 70 No separation. 20 7 70 Do. 20 7 70 D0. 20 7 70 Do. 20 7 70 10% white insoluble residue.

In order to illustrate the importance of the aforemengeneral, involves dilution of the cutting fluid to be evalutioned polyoxyalkylene glycol as an effective load-support ated with sterile nutrient broth (nutrient broth is used in place of distilled water in order to accelerate bacterial growth); inoculation from a standard bacterial culture;

agent in the novel aqueous lubricant compositions of the a present invention, it will be seen from the following Table III, that neither the triethanolamine, nor the aforemen and incubation for a period of 48 hours at C. Bacterial tioned ethylene oxide-propylene oxide copolymer, when growth is considered proportional to the increase in turused alone, or mixtures thereof (as in Examples 1, 2 and bidity of the sample.

3) are effective load-support agents, as indicated by the More specifically, the aforementioned biocide screening respective tapping efficiency, in each case, which is below test, which is used to determine bactericidal activity by 79 percent. Furthermore, as wiil be seen from Table III, visual observation of change in turbidity of a challenged the amine salts of the aforementioned C -C saturated solution, is carried out in the following manner. The organic acids, as represented by heptanoic, caprylic, and nutrient broth is prepared having the following compothe branched chain 2-ethyl hexoic acid, are more effective, ncnts, by weight:

but the tapping efficiency results are still below 89 percent. percent It will be noted, however, that a combination of the aforepeptone 5 mentioned ethylene oxide-propylene oxide copolymer and Be f extract 3 the aforementioned amine salts, produces tapping efiii ill 99 ciency results which range from 93 to 96 percent (as in Examples 5, 7 and 9). This represents a significant in- L) In accordance with the above-indicated proportions, the crease in tapping efficiency over the aforementioned amine peptone and beef extract are added to the water and the salts when used alone (as in Examples 4, 6 and 8). It will, resulting mixture is sterilized (autoclaved at 270 F for therefore, be apparent that there is a synergistic extreme 30 minutes). The sterile broth is then removed from the pressure effect between the aforementioned polyoxyalkylautoclave and allowed to cool to ambient temperature. ene glycol and the amine salts. The contents of one ampoule of freeze-dried bacteria TABLE III.AQUEOUS SYSTEMS CONTAINING AN ALKANOLALIINE, OR SATURATED ORGANIC ACID OR ETIIYLENE OXIDE-PROPYLENE OXIDE COPOLYMEES, OR MIXTURES THEREOF Base Formula Example No. Triethancl- Hcptanoie Caprylic Q-Ethyl Hcxoic copolymer Distilled Tapping Eiliciency,

' Acid Acid Acid amine (Percent Water Percent 1-5 Dilution (Percent (Percent (Percent (Percent Wt.) (Percent Base Formula-Dist.

W t.) V t. Wt.) Wt.) Wt.) Water From the foregoing, 1t W1ll be apparent that the novel moculum (primarily staphylococcus albus), which yields aqueous lubricant compositions of the present invention h approximately 634 million bacteria per milliliter when comprising an alkanolamine, a saturated organic acid hav- O the contents of the ampoule are added to 25 ml. of sterile ing from about 6 to about 9 carbon atoms per molecule, nutrient broth and are incubated for 24 hours at 30 C., and a polyoxyalkylene glycol, exhibit Outstanding propis added to 100 ml. of nutrient broth prepared in accorderties as evidenced from the abovedescribed data, from a ance with the above-described procedure in a 500 ml. standpoint of corrosion-resistance, hard Water stability Erlenmeyer flask. The flask and contents are placed in an and machining efficiency. incubator overnight at a temperature of 30 C. for growth.

9 At the end of this period, the flask is removed and ml. of sterile glycerol are added and mixed for a period of one minute. Vials are prepared containing 2 ml. of this mixture (inoculum) and placed in a freezer until needed.

ml. of the nutrient broth, prepared as previously described, are added to a 50 ml. Erlenmeyer flask which is plugged with cotton and autoclaved for minutes at 270 F. The flask is then removed from the autoclave and allowed to cool at ambient temperature. 0.5 ml. of the inoculum and 0.5 ml. of the sample under test are then added to the flask which is again plugged with sterile cotton and placed in an incubator shaker for 48 hours at 30 C. The presence of turbidity at the end of a test period indicates bacterial growth and, therefore, failure in the test.

Table IV, below, shows the data obtained in which a halogenated cresol as typical of the germicides of the present invention, and as represented by para-chloro-metacresol and other related germicidal agents, were evaluated for their bacterial growth-inhibiting effects.

2. The lubricant composition of claim 1 wherein said alkanolamine is present in an amount from about 20 to about percent, by weight; said organic acid is present in an amount from about 1 to about 4 percent, by weight; and said polyoxyalkylene glycol is present in an amount from about 0.5 to about 5 percent, by weight.

3. The lubricant composition of claim 1 containing as an additional component a germicidal agent selected from the group consisting of halogenated cresols, aldehydes, formaldehyde and tris (hydroxymeth yl)nitromcthane in an amount from about 0.05 to about 5 percent, by weight.

4. A lubricant composition containing a major proportion of water; a water-soluble alkanolamine in an amount from about 5 to about percent, by weight; a saturated organic acid having from about 6 to about 9 carbon atoms per molecule, selected from the group consisting of straight-chain organic acids and branched-chain organic acids, in an amount from about 0.1 to about 9 percent, by weight; a water-soluble polyoxyalkylene glycol in an amount from about 0.5 to about 20 percent, by weight;

TABLE lV.-BIOCIDE SCREENING TEST-SHAKER METHOD Base Formula 'Iriethanol- Bacterial growth rating 0.5

Ex. I Caprylic Copoly- Parachloro- Parachloro- Phenol Orthobenzyl- Distilled part base formula 20 parts No. anune c1 mer 1 metacresol metaxylenol (Percent parachloro- W ater nutrient broth (Percent (Percent (Percent (Percent (Percent Wt.) phenol (Percent W t.) W t.) Wt.) Wt.) Wt.) (Percent Wt.) Wt.)

20 3 7 70 Fail.

20 3 7 69 Pass, no bacterial growth.

20 3 7 69 Fail.

l Copolymer prepared from ethylene oxide and propylene oxide.

From the foregoing data of Tables I through IV, it will be apparent that the novel aqueous lubricant compositions of the present invention comprising a water-soluble alkanolamine, a saturated organic acid having from about 6 to about 9 carbon atoms per molecule, a water-soluble polyoxyalkylene glycol and a germicide, such as a halogenated cresol, exhibit outstanding properties from a standpoint of corrosion resistance, hard water stability, machining efficiency and eflicacy in inhibiting bacterial growth. It will also be noted that the germicidal agents of the lubricant compositions of the present invention are effectively stabilized by the amine salt, i.e., the amine salt tends to solubilize the germicidal agent and thereby avoids precipitation of the latter, which would otherwise interfere with lubricating and machining efiiciency. More specifically, with respect to the efiicacy of the halogenated cresols in effectively inhibiting bacterial growth, it will be noted from Table IV that other closely related compounds, such as parachloro-meta-xylenol, phenol or ortho-benzyl-para-chlorophenol, were unsatisfactory as indicated by excessive growth in the above-described biocide screening test.

While preferred embodiments of the compositions of the present invention and the method for their preparation have been described for purposes of illustration, it will be understood that various modifications and adaptations thereof, which will be obvious to those skilled in the art, may be made without departing from the spirit of the invention.

I claim:

1. A lubricant composition containing a major proportion of water, from about 5 to about 40' percent, by weight, of a water-soluble alkanolamine, from about 0.1 to about 9 percent, by weight, of a saturated organic acid having from about 6 to about 9 carbon atoms per molecule, selected from the group consisting of straight-chain organic acids and branched-chain organic acids, and from about 0.5 to about 20 percent, by weight, of a watersoluble polyoxyalkylene glycol.

and a halogenated cresol in an amount from about 0.05 to about 5 percent, by weight.

5. The lubricant composition of claim 4 wherein said alkanolamine is present in an amount from about 20 to about 35 percent, by weight; said organic acid is present in an amount from about 1 to about 4 percent, by weight; said polyoxyalkylene glycol is present in an amount from about 0.5 to about 5 percent, by weight; and said halogenated cresol is present in an amount from about 0.5 to about 3 percent, by weight.

6. The lubricant composition of claim 4 wherein said halogenated cresol is a chlorinated cresol.

7. The lubricant composition of claim 4 wherein said halogenated cresol is para-chlorometa-cresol.

8. The lubricant composition of claim 4 containing as an additional component from about 0.1 to about 10 percent, by weight, of an alkali metal nitrite.

9. The lubricant composition of claim 4 containing as an additional component from about 0.1 to about 6 percent, by weight, of sodium mercapto-benzothiazole.

10. The lubricant composition of claim 4 containing as an additional component from about 0.1 to about 5 percent, by weight, of boric acid.

References Cited UNITED STATES PATENTS 2,605,206 7/1952 Rowzet 1 67-38] XR 2,625,509 1/1953 Laug 252-347 2,825,693 3/1958 Beaubien et a1 252-493 2,951,041 8/1960 Saunders 252-347 3,201,349 8/1965 Quanstrom s 252-495 XR 3,202,607 8/1965 Koch 252-495 3,244,630 4/1966 Sheikh 252-495 3,311,557 3/1967 Schiermeier et al. 252-495 XR DANIEL E. WYMAN, Primary Examiner.

C. F. DEES, Assistant Examiner.