US3436348A

US3436348A - Ester base lubricating oil containing a stabilizing mixture of alkali metal organic compound and an aromatic amine

Info

Publication number: US3436348A
Application number: US587990A
Authority: US
Inventors: Tai S Chao; Howard J Matson; Manley Knonaas
Original assignee: Sinclair Research Inc
Current assignee: Sinclair Research Inc
Priority date: 1966-10-20
Filing date: 1966-10-20
Publication date: 1969-04-01
Anticipated expiration: 1986-04-01

Description

United States Patent ESTER BASE LUBRICATING OIL CONTAINING A STABILIZING MIXTURE OF ALKALI METAL ORGANIC COMPOUND AND AN AROMATIC AMINE Tai S. Chao, Homewood, and Howard J. Matson, Harvey, Ill., and Manley Knonaas, Hammond, lnd., assignors to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware N 0 Drawing. Continuation-impart of application Ser. No. 411,718, Nov. 17, 1964. This application Oct. 20, 1966, Ser. No. 587,990

Int. Cl. Cm 1/38, ]/32, N US. Cl. 25233.6 19 Claims This application is a continuationin-part of copending application Ser. No. 411,718, now abandoned, 'filed Nov. 17, 1964, which in turn is a continuation-in-part of application Ser. No. 285,587, now abandoned, filed June 5, 1963.

This invention relates to ester-based lubricant compositions containing a novel combination of additive agents. More particularly the present invention relates to esterbased lubricant compositions which exhibit increased oxidation resistance.

Organic compounds, such as lubricating oils, undergo oxidation upon exposure to air. This process is accentuated by elevated temperatures such as occur in engines and other operating machinery. When such organic compositions are used as motor or machinery lubricants, their stability is still further drastically reduced 'due to their contact with metal surfaces which give up metallic particles into the lubricant. Such abraded or dissolved metals or metal salts appear to act as oxidation catalysts in the lubricant causing the formation of primary oxidation products which in turn cause further degradation of the organic compounds present in the composition. Problems of this nature are encountered in mineral oils but appear to be particularly troublesome in synthetic oleaginous fluids exemplified by esters.

The development of modern high speed jet turbine aircraft engines necessitates the search for lubricants which are resistant to high temperature oxidative degradation. Jet turbines are actuated by the energy of a burning fuel and are used to drive compressors which provide large amounts of air for the burning of the fuel. The comibustion of the fuel provides the energy for driving the compressors with the remainder of the useful energy going into the propulsion of the aircraft. Jet turbine bearings are lubricated by pumping a lubricant to the bearings from a reservoir in a closed system. The design of more powerful jet turbines has led to an increase in the lubricant reservoir temperature and to greater difficulty in maintaining lubricant stability under the more severe conditions. For example, a lubricant which will operate satisfactorily at a reservoir temperature of 250 F. may sludge badly. build up viscosity, develop high acidity and corrode metals at a reservoir temperature of 440 F.

Thus jet turbine service requires a lubricant of superior thermal and oxidation stability as well as satisfactory physical chracteristics in terms of viscosity, flash point, volatility, and load carrying properties. To arrive at such a lubricant it has been the general practice to add an antioxidant and other additives, such as foam inhibitors, anti-wear agents, etc., to a base fluid of suitable properties.

Numerous oxidation and corrosion inhibitors have been ice found for use in lubricating compositions and many combinations thereof also have been tested. For instance, antioxidants such as phenothiazine; phenyl-a-naphthylamine; 5-ethyl-10,lO-diphenylphenazasilane; etc. are well known in the art. The known inhibitors, however, are not adequate to provide the superior oxidation resistance now needed. Moreover, the effectiveness of these known inhibitors is greatly impaired in the presence of metal.

It is the object of this invention to provide an ester base synthetic lubricant having superior resistance toward oxidative and thermal degradation. It is a further object to protect and improve this resistance against the detrimental etfects of metals with the use of suitable additives.

The present invention provides an improved esterbased lubricant composition having dissolved therein small amounts effective to retard oxidation, of an aromatic amine and an alkali metal. In order to be dissolved in the base oil, the alkali metal is added as an alkali metal organic compound. Thus, the active component in combination with the aromatic amine is a soluble form of an alkali metal such as Na, K, Li, Cs and Rb. Typical organic compounds which form suitable alkali metal derivatives are carboxylic acids, phenols, alcohols, ketones, aldehydes, various chelating agents, etc., often of about 2 to 50 or more carbon atoms, preferably about 4 to 30 carbon atoms. Although the alkali metal is an essential active component, we have found that certain classes of alkali metal derivatives or salts of acidic organic compounds are especially effective in enhancing oxidation inhibiton. Exemplary of these acidic organic compounds are unsubstituted and S, O, N and halogen substituted carboxylic acids, phenols, including thiophenols, beta diketones and Schitfs bases. However, the invention is not limited to the compounds disclosed because the oxidation inhibition obtained with an aromatic amine and soluble alkali metal is believed to be a general phenomenon applicable to the various alkali metal compounds which are soluble in the base ester fluid to the extent needed to impart an antioxidant effect.

The carboxylic acids which may be employed to make the alkali metal salts include monoand polycarboxylic acids, for instance, those having straight, branched or cyclic hydrocarbon structures, including talkylated benzoic acids. The carboxylic acids may be saturated or unsaturated and may often contain from about 4 to 22 or even up to 50 or more carbon atoms. Examples of suitable fatty acids are capyrlic, isodecanoic, isostearic, cerotic, myristic, cyclohexanoic, cyclooctanoic and ethyl cyclooctanoic acids. A group of monocarboxylic acids which can be used is represented by the formula RCOOH wherein R is an alkyl, aryl, aralkyl or alicyclic hydrocarbon radical of 3 to 21 carbon atoms.

Other suitable carboxylic acids for making the alkali metal derivative include those substituted with groups containing, for instance, S, O, N and halogen. The substituted carboxylic acids may be saturated or unsaturated and may preferably contain from about 2 to 36 carbon atoms. The base or parent carboxylic acid may be aromatic or aliphatic, for instance, alkanoic, including cycloalkanoic, benzoic or a mixed aliphatic-aromatic acid. The sulfur-containing carboxylic acids include mercaptans, thioethers, thioacids and sulfones which contain a carboxylic acid group. Exemplary of the sulfur-containing compounds are 4-thiadodecanoic acid, mercaptoacetic acid, thiosalicylic acid, 4-mercaptooctanoic acid, thiooctanoic acid, thiododecanoic acid, thioacetic acid, 2-(butyl sulfonyl) acetic acid. A group of suitable sulfur-containing monocarboxylic acids can be represented by the formula:

0 R(ii0)m-Ri.'sRC0oII wherein R is an alkyl radical of 6 to 20 carbon atoms, R is an alkylene radical of 1 to 8 carbon atoms, e.g.

CH CH m is 0 or 1, n is 0 or 1 and m -n. The acids include etc. The oxygen-substituted carboxylic acids include ether acids, hydroxy acids and keto acids. Exemplary of the oxygen-substituted carboxylic acids are 3-hydroxy-1-butanoic acid, 6-hydroxy octanoic acid, salicylic acid, 4-hydroxy-6-phenyl-hexanoic acid, 3-ethoxy-1-butanoic acid, etc. The nitrogen-substituted carboxylic acids may contain nitro, amine and amide substituents. For example, we may use the alkali metal salts of 6-aminohexanoic acid, 6- amino-S-phenyl-octanoic acid, the tributyl ester of ethylene diamine tetraacetic acid, o-amido-pentanoic acid, 6-N- methyl-amido nonanoic acid and 2-nitrobutyric acid. A group of suitable N-containing monocarboxylic acids can be represented by the formula:

wherein R is an alkylene radical of 1 to 8 carbon atoms, R is an alkylene radical of 2 to 8 carbon atoms, R" is an alkyl radical suificient to impart ester base oil solubility to the additive, e.g. up to about 18 carbon atoms on the average, often at least about 4 carbon atoms, a, b, c, and dareOor 1,eis0to2,whenbis 1,ais l,whendis l, c is 1 and e is 2, and when dis 0 and c is one, e is 1. Also when b is 0 and a is l, c and d are 0. Exemplary compounds of this type include:

/CH1C O0 Butyl NCII:COO Butyl (a:1, b:

(3111C OOII The halogen substituents may be fluorine, chlorine, bromine or iodine. Examples of halo-substituted carboxylic acids are perfluoro acetic acid, perfluoro butyric acid, 0:- H-polyfluoro heptanoic acid, perfluoro benzoic acid, 3,5- difiuoro methyl benzoic acid, trichloro acetic acid, 18- bromo acetic acid, monochloro difiuoro acetic acid, pentachlorophenoxyacetic acid, etc. Acids having at least 50% of their hydrogen replaced by halogen are preferred, especially the perhalogen acids.

The alkali metal salts of halogen-substituted, lower alkanoic monocarboxylic acids, i,e., lower fatty acids, in addition to their outstanding antioxidation effect in combination with amine antioxidants, have many other properties which qualify their use in synthetic lubricants. In the first place they are sufliciently soluble in ester type base fluids. For example, lithium perfluorobutyrate is soluble at more than 50% by weight in either Hercolube A or Hercolube F. Sodium perfluorobutyrate, although less soluble than the lithium salt, is soluble at several times the necessary concentration even at 40 F. In the second place, these salts are derived from strong acids and strong bases and are therefore compatible with the weak acids present in synthetic lubricants which are either added as additives or are formed during the service life of the lubricant. In the third place they have no adverse effect on the seal materials used in aircraft jet engines, including Viton O-rings, carbon seals and H-rubber seals.

The phenols suitable for preparation of the alkali metal phenates may contain as substituents, for example, alkyl, acyl or amido groups and often have from about 7 to 24 carbon atoms. Examples of suitable phenols are p-lauroylamino phenol, t-butyl phenol, t-octylphenol, dodecyl phenol, nonyl phenol, p-aminophenol, N-phenyl-p-aminophenol and condensation products of phenol, formaldehyde and primary or secondary amines such as Ii /41h The useful phenols include those of the formula:

XII

wherein X is O or S, R is alkyl of 4 to 18 carbon atoms on the average, and n is l to 3.

The ketones which may be used to form the alkali metal derivatives include further substituted materials such as keto esters and keto amides. The ketones preferably contain from about 5 to 22 carbon atoms. The ketones may be aliphatic, aromatic or mixed aliphatic-aromatic and they may be saturated or unsaturated and substituted with nondeleterious substituents. Examples of suitable compounds are acetyl acetone, ethyl aceto acetate, N,N-dimethyl aceto acetamide, 1,3-diphenyl-1,3-propanedione, ethyl formylacetate, and ethylbenzoyl acetate.

Schifts bases e.g., of about 4 to 30 carbon atoms which are condensation products of aldehydes or ketones with primary amines are also effective as the alkali metal derivative-forming compounds. Examples of suitable Schiffs bases are bis(salicylidene) propylene diimine, bis(acetylacetone)-ethylenediimine, N-phenyl-N,N' bis(salicylidene)ethylenediimine, etc.

The aromatic amine component of the invention is soluble in the ester fluid at least to the extent used and can be represented by the following general formula:

wherein Q is a monovalent hydrocarbon radical of l to 20 carbons, preferably 6 to 12 carbon atoms, whose adjacent carbon atoms are no closer than 1.40 A. (i.e. a non-olefinic, non-acetylenic, monovalent hydrocarbon), and Q is a non-olefinic, non-acetylenic aromatic hydrocarbon radical of 6 to 12 or 16 carbon atoms. Thus Q can be an alkyl group, including cycloalkyl, or an aromatic group. Preferably, both Q and Q are aromatic, and often at least one is a fused ring aromatic, e.g. naphthyl. Q and Q can be substituted with non-interfering substituents such as alkyl, aryl, hydroxyl and amine groups, preferably alkyl or aromatic amines, and Q and Q can be linked together by means of a non-interfering element such as carbon,

sulfur and oxygen. Illustrative of suitable amines are phenothiazine, N-phenyl-a-naphthyl amine; di(|x-naphthyl amine N,N'-diphenyl para-phenylene diamine; N,N'-dioctyl para-phenylene diamine, N,N'-diheptyl-para-phenylene diamine; diphenyl amine, p-octyl diphenylamine; p-pdioctyl diphenylamine; etc.

The lubricant composition of this invention includes as the major compound a base oil which is an ester of lubricating viscosity which may be, for instance, a simple ester or compounds having multiple ester groupings such as complex esters, dior other polyester, and polymer esters. These esters are usually made from monoand polyfunctional aliphatic alcohols or alkanols, and aliphatic monoand polycarboxylic or alkanoic acids. Frequently, the alcohols and acids have about 4 to 12 carbon atoms. The reaction product of a mono-functional alcohol and a monocarboxylic acid is usually considered to be a simple ester. A diester is usually considered to be the reaction product of 1 mole of a dicarboxylic acid, say of 6 to carbon atoms, with 2 moles of a monohydric alcohol or of 1 mole of a glycol, for instance, of 4 to 10 carbon atoms, with two moles of a monocarboxylic acid, e.g. of 4 to 10 carbon atoms. The diesters frequently contain from 16 to 40 carbon atoms.

A complex ester is usually considered to be of the type XY--ZY-X in which X represents a mono-alcohol residue. Y represents a dicarboxylic acid residue and Z represents a glycol residue and the linkages are ester linkages. Those esters, wherein X represents a monoacid residue, Y represents a glycol residue and Z represents a dibasic acid residue are also considered to be complex esters. The complex esters often have 30 to 50 carbon atoms.

Polymer esters or polyester bright stocks can be prepared by direct esterification of dicarboxylic acids with glycols in about equimolar quantities. The polyesterification reaction is usually continued until the product has a kinematic viscosity from about to 200 centistokes at 210 F., and preferably 40 to 130 centistokcs at 210 F.

Although each of these products in itself is useful as a lubricant, they are particularly useful when added or blended with each other in synthetic lubricant compositions. These esters an blends have been found to be especially adaptable to the conditions to which turbine engines are exposed, since they can be formulated to give a desirable combination of high flash point. low pour point, and high viscosity at elevated temperatures. In addition, many complex esters have shown good stability to shear. Natural esters, such as castor oil may be employed and also be included in the blends, as may be small amounts of a foam inhibitor such as a methyl silicone polymer, or other additives of lubricant components to provide a particular characteristic, for instance, extreme pressure or load carrying agents, corrosion inhibitors, etc., can be added.

The monohydric alcohols employed in these esters usually contain about 4 to carbon atoms and are generally aliphatic. Preferably the alcohol contains up to about 12 carbon atoms. Useful alkanols include butyl, hexyl, n-octyl, isooctyl and dodecyl alcohols, C oxo alcohols and octadecyl alcohols. C to C branched chain primary alcohols are frequently used to improve the low temperature viscosity of the finished lubricant composition. Alcohols such as n-decanol, 2-ethylhexanol, oxo" alcohols, prepared by the reaction of carbon monoxide and hydrogen upon the olefins obtainable from petroleum products such as diisobutylene and C olefins. ether alcohols such as butyl carbitol, tripropylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, and products such as Tergitol 3A3 which has the formula C H O(CH CH O) I-I, are suitable alcohols for use to produce the desired lubricant. If the alcohol has no hydrogens on the beta carbon atoms, it is taco-structured; and esters of such alcohols are often preferred. In particular, the nee-C alcohol2,2,4-trimethyl-pentanol-1 gives lubricating diesters or complex esters suitable for blending with diesters to produce lubricants which meet stringent viscosity requirements. Iso-octanol and isodecanol are alcohol mixtures made by the oxo process from C -C copolymer heptenes. The cut which makes up rsooctanol usually contains about 17% 3,4dimethylhexanol; 29% 3.5-dimethylhexanol; 25% 4,5-dimethylhexanol; 1.4% 5,5-dimethylhexanol; 16% of a mixture of 3- methylheptanol and S-ethylheptanol; 2.3% 4-ethylhexanol; 4.3% u-alkyl alkanols and 5% other materials.

Generally, the glycols contain from about 4 to 12 carbon atoms; however, if desired they could contain a greater number. Among the specific glycols which can be employed are 2-ethyl-l ,3-hexanediol, 2-propyl-3,S-heptanediol, 2-methyl-1,3-pentanediol, 2-butyl-l ,3-butanediol, 2,4-diphenyl-l,3 butanediol, and 2,4-dimesityl-1,3-butanediol.

In addition to these glycols, ether glycols may be used, for instance, where the alkylene radical contains 2 to 4 carbon atoms such as diethylene glycol, dipropylene glycol and ether glycols up to 1000 to 2000 molecular weight. The most popular glycols for the manufacture of ester lubricants appear to be polypropylene glycols having a molecular weight of about -300 and Z-ethyl hexanediol. The 2,2-dimethyl glycols, such as neopentyl glycol have been shown to impart heat stability to the final blends. Minor amounts of other glycols or other materials can be present as long as the desired properties of the product are not unduly deleteriously affected.

One group of useful monocarboxylic acids includes those of 8 to 18 or even 24 carbon atoms such as stearic, lauric. etc. The carboxylic acids employed in making ester lubricants will often contain from about 4 to 12 carbon atoms. Suitable acids are described in US. Patent No. 2,575,195, and include the aliphatic dibasic acids of branched or straight chain structures which are saturated or unsaturated. The preferred acids are the saturated aliphatic carboxylic acids containing not more than about 12 carbon atoms, and mixtures of these acids. Such acids include succinic, adipic. suberic, azelaic, and sebacic acids and isosebacic acid which is a mixture of a-ethyl suberic acid. a,a'-diethyl adipic acid and sebacic acid. This composite of acids in attractive from the viewpoint of economy and availability since it is made from petroleum hydrocarbons rather than the natural oils and fats which are used in the manufacture of many other dicarboxylic acids, which natural oils and fats are frequently in short supply. The preferred dibasic acids are sebacic and azelaic or mixtures thereof. Minor amounts of adipic used with a major amount of sebacic may also be used with advantage.

The ester base oils to which incorporation of the additive combination of the invention is particularly advantageous are the oils commonly referred to as neostructured polyol polyesters. i.e. having more than one ester group. These are the esters of aliphatic carboxylic acids, generally monoalkanoic acids, of about 4 to 12 carbon atoms, and a polyhydric alkanol free of beta hydrogen, i.e. containing no hydrogen on the beta carbon atoms, and including the di(polyhydric alcohol) ethers. The polyhydric alcohol generally contains about 2 to 6 hydroxy groups and about 5 to 20 preferably 5 to 12 carbon atoms. Illustrative of the alcohols are those having the general formula:

wherein n is O to l and R is a lower alkyl group, preferably of about 1 to 4 carbon atoms, which can be straight 7 or branched chain, or a hydroxy lower alkyl, e.g. hydroxy methyl, group. These esters can be made by reacting a mole of the alcohol with about 2 moles up to the stoichiometric equivalent of the carboxylic acid.

Illustrative of polyhydric alcohols free of beta hydrogen are neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, 2-butyl-2- ethyl-1,3-propanediol, etc. Suitable aliphatic carboxylic acids with which the polyhydric alcohols free of beta hydrogen may be esterified are n-butyric acid, isobutyric acid, valeric acid, isopentanoic acid, caproic acid, isohexanoic acid, n-heptanoic acid, isoheptanoic acid, neoheptanoic acid, n-octanoic acid, isooctanoic acid, pelargonic acid, n-decanoic acid, isodecanoic acid, neodecanoic acid, lauric acid, myristic acid, stearic acid, isostearic acid, etc.

The amine and alkali metal additives of the invention are incorporated in the base oil in small amounts sufficient to retard oxidation of the oil at temperatures in excess of 400 F. and the concentrations employed for optimum results may be dependent on the particular base oil and second additive component selected. The amount of the additives is insufficient to destroy the fluidity of the base ester oil, i.e. the oil remains essentially liquid at normal conditions and the alkali metal component is not used in an amount which produces a grease or gel-like structure. Ordinarily about 0.005 to preferably about 0.01 to 2%, by weight of the alkali metal derivative provides satisfactory results. The amine additive component provides satisfactory results when present in amounts of about 0.05 to 5% and preferably about 0.1 to 2%. Other additives such as antiscuff and antifatigue additives, antifoams, etc., can also be advantageously used with the organic alkali metal compounds of this invention. The viscosity of the lubricating oil containing the additives is preferably less than about 13,000 centistokes at --40 F.

The effectiveness of the organic alkali metal derivatives of his invention is shown by the following examples which are not to be considered limiting.

EXAMPLE I The following lubricant formulation was prepared by mixing the components at l50l60 F. The Sodium perfiuorobutyrate was first dissolved at 250 F. in about 100 times its weight of Hercolube A and then blended with the other components.

Wt. percent The sample was filtered through paper and submitted for tests indicated. The results were as follows:

(1) O Absorption Test, 450 F., 1 ft. O /hr. 75 g.

sample T min Tt a a A ,ClOu V ml Type II Bearing Rig Test:

Acid No., final 0.93 Viscosity rise, final. (KV/l00) fi percent 50.0 WADD Demerit rating 58 100 Mesh filter deposit, gm. 1.24

8 (3) Ryder Gear Scuff Test Scufi load:

A side, lb./in. 2590 B side, lb./in. 2860 Relative rating percent-..

(4) Gear Fatigue Test-more than hours. (5) Corrosion-Oxidation Test (425 F., 48 hours) Wt. Change, mg./cm.

Cu 0.30 Ag +0024 Steel +0.054 Al +0.00? Mg 0.77 Ti +0038 Viscosity rise, (KV/l00) percent 22.2 Acid N0. increase 1.27

(6) SOD P1) corrosion, 325 F., 1 hr., mg,/in.- +6.48,

(7) Carbon seal wear, inches/min.0.017 l0 (8) Inspection tests:

KV/210 F., cs 5.104. KV/l00 F., cs 27.63. KV/40 F., cs. 9.824. Flash point, F. 495. Pour point, F Below 80. Acid No. (pHll) 0.3.

000. Foam Test 0-0-0. 000. Percent Swell, H rubber 26.1. Percent Swell, Viton 18.4. Durometer, Viton 65.

Evaporation loss, 6.5 hrs:

400 F., sea level percent" 3.41.

450 F., 5.5" Hg d0 18.62 Percent Sonic shear None. 40 F., 72hr. storage a- Clear and fluid.

1 A Dow Corning antifoam silicone antifoa1uing agent havlug a viscosity of 200 cs, at 250 C. and t]. molecular weight of 60.000.

Described or identified below.

An extreme pressure agent.

The above tests indicate that the ester lubricant containing an alkali metal additive and amine is very resistant to oxidation and also satisfies other requirements of a good high temperature lubricant.

In order to point out the improvement obtained by combining the alkali metal additives of this invention with an aromatic amine antioxidant, a series of oxidation tests were run on synthetic lubricants containing no oxidation inhibitor, aromatic amine inhibitors alone and aromatic amines in combination with an organic alkali metal compound. The oxygen absorption tests comprised passing a stream of oxygen at the rate of one cubic foot per hour through 75 grams of the ester fluid containing the inhibitors maintained at a temperature of 450 F. and comparing the amount of oxygen absorbed vs. time. The volume of oxygen absorbed was indicated by a Statham gauge and was plotted automatically on a Brown recorder. The induction period (Ti) is the time in minutes in which comparatively little oxygen is absorbed by the base fluid. The end of the induction period is signalled by a marked increase in the rate of oxygen absorption and Vi indicates the milliliters of O absorbed in time Ti, Tt indicates the time observed to absorb the total oxygen V1. The results of these tests and the identity of the base fluids used are reported in Table I.

The data in Table I indicate that the oxidation inhibition obtained from an aromatic amine inhibitor is greatly improved by using a combination of the aromatic amine and an organic alkali metal compound.

TABLE I Base Absorption Test Data fonnu- Alkali Metal Compound Wt.

lotion percent T4,

min. min

Sample No;

None 2'24 266 512 2, 500 Na Ll'iCiliOl'OdtGiflHL 0. 0|) 745 708 1, 500 2, 500 N a di-snlicylidel1e-propylene 0. 11 306 348 780 2, 500

diimiue. Na p-luuroyliiininophenoliite. 0. 11 202 373 010 2, 500 No octyl-nhenolutc 0. 400 501 708 .1, 500 N-phenyl-N,N'-his(suli 0. 10 280 321 757 500 cylidene) ethylene-domino. Na isodecnnootc 0. 07 458 308 730 2. 500 No 4-tliiadodeconoatc 04 10 410 463 802 2, 500 No derivative of the condom 0. 11 354 394 (552 2, 500

sution product of Unity]- phenol formaldehyde and 0102 626 (101 1, .110 .4, 500 ill 0i QIS 9-18 1, 355 500 0. 07 442 4T2 1, 087 2, 500 U. 03 700 1, 1'25 2, 500 0106 528 550 1, (ill) 2, 500

B Nonc 224 255 1, 050 2, 500 i; 2 Na :ieetylucotonnte. 0.1 501 525 L 600 2, 500 B 2 No commute"... i 0.1 324 339 1, 825 l, 500 B 2 No 1SOSi1li11li0 i, 3 0. 1 319 353 1, 2, 500 B i1 02 596 020 1, 801) 2. 500 B 2 0.05 1,[)12 1,012 2, 500 B Z C FyCOO Li 0. 075 710 716 .s 2, 500

1 Base Formulation A contained 7597,1111 and 25% 11F to which was added 1%01PAN tN-pbcnyl-a-naphtllyl amino).

2 llusc Formulation B was the some as host formulation A cxcept that the formulation also had 1% of p,p'- dioctyl diphcnyl mninc added based on the HA mid IIF.

11A. is an csscntinlly complete pfntoerytliritol ester of fatty I'Kitlfi hnviru on average of 0 carbon atoms and with the following npnroxirnotc inspection data: Acid Noi, 0.01; Snponiiiuntion No., 410; Viscosity at 210 I 1, 510 cs: Viscosity at 100 F., .151.

11F, is on csscntinlly complete ester of dipeutacrythritol and u mivturo ofsllmnoic acids containing an average of 51o 6 carbon atoms per niolcculc and characterized by an avid number of about 041, u simouiiicution number oi about 391. 0.3% bydroxyl, and u kinematic viscosity 11L 210 1 019.1 es. and at 100 F. 0162 cs.

3 The sodium suit was dissolved in methanol before addition to the base iormulzttion and the solvent was removed under reduced pressure.

The effectiveness of the organic alkali metal additives is not limited to a specific synthetic base fluid or aromatic amine inhibitor. As indicated by Tables 11 and III, great improvement in oxidation inhibition was obtained with a wide variety of base fluids and aromatic amines.

TABLE 11 Conn. Oz absorption test data Base Fluid Additives Wt. percent Ti, 'It, Vi, Vt, Inin min. m1. m1.

Sample No:

1 Celaucsc 704 PAN 1.0 111 148 522 2, 500 2.. Celuncsc 704 {5;, 635 600 1,190 2, 500 3 1111101201 gighflh 1.0 39 78 250 2, 500

1.0 4 2 1 121 201.1; ..{CEFICOONLH 360 360 2. 500

0 omp ex stor 5 (Dmy, 110 1 5 415 2,500

80' Toiilplox Ester PAN 1.0 6 "{207 Diociyl Azelate ciFicooNaqfl 0.1} 364 4m 1420 2-500 1 7 Pcntaerythritol tetracaproato. {gfi 3 1,115 1,218 1,200 2, 500 8 Dipcntanryibritolhexabutyrate" {gfiil 1 Synthetic lubricant base stock producedcby Lcliincsu and containing trimethylolpropenc esters of fatty acids having on avorago chain length of 6 to 7.

2 Diethyiiwxyl scbacate oil having a kimunatic viscosity at 100 F. of 12.3 05., a viscosity index of 154, a

pour point bclow -80 l", and acid No. of 0112.

3 Complex ester in-pared from 1 mole nuopr'ntyl glycol, 52 moles azvloic acid and 2 moles isooctyl alcohol.

TABLE III Gone. Absorption Test Data Aromatic Amine Wt.

percent T.-, T, V4, V1. min. min. ml. ml.

Sample No.:

1... NH-NH 1.0 1,245 1,245 2,500

2 NHN1I 1.0 i,103 1,103 1,050

(Ficxzone 611) a iPr-NIINII 1.0 1,Tl0 1,110 1,500

(Flexzone 3C] 4 Di-a-naphthylaminc 1.0 458 514 742 2,500 5. Dl-8-naphthylamiue. 1.0 025 738 1,150 2,500 6. Ortholeum 300 1.0 690 1,200 800 2,500 7. Vanlube 60 1.0 2,305 2,305 2, 500 8. Phenothiazine. 1.0 292 329 1,100 2,500

l A diphenylaminc type antioxidant produced by du Pont.

2 A rubber antioxidant produced by R. T. Vanderbilt Co. comprising primarily monooctyl diphenylamine.

A group of alkali metal derivatives of nitrogen substituted fatty acids which are particularly effective antioxidant additives are the monoalkali metal salts of trialkyl esters of alkylene diamine tetraacetic acid which may be represented by the following formula:

wherein M is the stoichiometric equivalent of an alkaline metal, that is, an alkali metal such as Na, K, Li, Cs and Rb; Z is an alkylene radical including cycloalkylene, of l to carbons, preferably 2 to 12 carbons and can be interrupted with one or more non-interfering elements such as oxygen and nitrogen and substituted with noninterfering substituents such as lower alkyl groups; and R is a hydrocarbon radical having on the average about 3 to 18 carbon atoms, whose adjacent carbon atoms are no closer than 1.40 A, (i.e. a non-olefinic, non-acetylenic, monovalent hydrocarbon). Thus, R can be an alkyl radical (including cycloalkyl) straight or branched chain, preferably of about 4 to 8 carbons on the average, or an aryl radical and can be substituted with non-interfering groups such as hydroxy and alkyl groups. The R groups can be the same or different and are of sufiicient molecular weight to render the salt of the triester soluble in the base oil. Illustrative of alkylene radicals represented by Z are (CH wherein x=l to 20;

(EH-(EH on, 0112 CHrCfig -CHQCHFOAGHQCH2; CHz'CH-20C 11 -01120 CH -CH CH -CHzNCHgCHz; and GHz-CHz-N-0Hz-CH2- HQCOOR H COOM where R and M are as designated above.

The monoalkali metal salts can readily be prepared by partial saponification with an alkali metal base of the tetraesters of the alkylenediamine tetraacetic acid obtained, for instance, by the method described in US. Patent No. 2,428,353 to Frederick Bersworth, hereby incorporated by reference. Suitable bases include for example, the hydroxides, carbonates, etc. of the alkali metals. Alternatively, the salts can be obtained as by-products of the process of the aforementioned patent. Briefly, the estcrification of the patent involves reacting a polycarboxylic amino acid with an alcohol in the presence of sutficiently strong mineral acid to form an amino acidmineral acid addition product, the reaction being carried out so that the Water resulting from the esterification reaction is driven off. Alernatively, the amino-mineral acid addition product is first prepared and separated as a crystalline product and esterified by heating with alcohol. On completion of the esterification reaction in either method, excess alcohol is removed by distillation which leaves the ester usually in the form of an addition product with the mineral zicid. To neutralize and remove the mineral acid, the ester product is treated before or after the alcohol removal, with an alkaline solution and in so doing forms at least in part the alkaline metal salts of the present invention which can be separated from the ester, if desired, by any suitable means such as solvent extraction. Generally the reaction product includes on the basis of the tetraester about 0.005 to 0.4 or even more equivalent weights of the alkali metal, preferably about 0.02 to CH. The monoalkali metal salts per se can be employed in the composition of this invention but it is preferred to utilize the mixture of monoalkali metal salt, tetraester and other by-products, as such, formed by the neutralization step of the process described in the aforementioned patent. We have referred to the monoalkali metal salt herein one the basis that all of the alkali metal up to an equivalent weight based on one -COOH group, is present as the mon-salt, Whereas in most instances, other salts, e.g. the di-metal salt of diester and the trimetal salt of monoester will also be present. However, the mono-salt would be the predominant salt in the mixtures. Ordinarily, the resulting neutralized ester product-mixture will contain anywhere from 3 to 40 Weight percent of monoalkali metal salt. Although it is preferred to use this mixture as such, should the monosalt by itself be desired, it can be separated from the ester mixture. Alternatively, a substantially pure tetraester is first prepared as described by the Bersworth patent and the substantially pure ester obtained saponified as with an equimolar amount of the alkali base in solution to give the monosalt on a calculated basis. If desired the polyalkali metal salts of the partial ester may be used.

The lubricants of this invention may also have added thereto, for instance see Example I, a small corrosioninhibiting amount of an ester of the formula:

wherein R and Z are as given above with respect to the alkali metal salts of compounds of this general structure. Aside from the tetraester, partial esters may be used, and as noted above, the partial ester alkali metal salts afford a means whereby the anti-corrosion properties of the ester as well as the antioxidant characteristics of the alkali metal can be obtained. The tetraesters and partial esters can, for instance, be used in the lubricant in the amounts indicated above with respect to the alkali metal compounds of the invention. Also, even though the tetraester be added to the lubricant it may be converted to a partial alkali metal salt form in situ when the alkali metal is present as a different salt, for example, of a weaker acid.

The Examples 11 to IV are included to illustrate various methods for the preparation of monoalkaline salts of trialkyl esters of ethylenediamine tetraacetic acid suitable for use in the composition of the present invention.

EXAMPLE II A mixture of 584 grams (2 moles) of ethylenediaminetetraacetic acid (EDTA), 2024 grams (15.6 moles) of noctanol and 400 grams of toluene was placed in a liter, 3-necked flask. With constant stirring and slow heating to 100 C., the mixture was saturated with anhydrous HCl. A Dean-Stark trap was installed and the reaction mixture was refluxed until 226 mils of water were collected in the trap. The reaction mixture was neutralized with aqueous Na CO and the organic layer was washed three times with water. Upon stripping at 130 C. and 1 mm., 660 grams of a viscous yellow liquid was obtained. Analysis indicated it to be the tetra-n-octyl ester of EDTA.

Twenty grams (0.50 mole) of sodium hydroxide was dissolved in 50 mls. water and diluted with 360 grams of 95% ethanol. To this was slowly added 370 grams (0.50 mole) of the tetram-octyl ester prepared above. The mixture was stirred at room temperature until pH became 78. The solvent and n-octyl alcohol were removed under vacuum, yielding 268 grams of viscous yellow liquid. Analyses showed the presence of 3.55% Na and 4.73% N. The calculated values for the monosodium salt of tri-noctyl ester of EDTA are 3.54 and 4.31, respectively.

EXAMPLE III Eight grams (0.2 mole) of sodium hydroxide was dissolved in 8 grams of water and the solution was diluted with 92 grams of n-BuOH. To this was added 1032 grams (0.2 mole) of the tetrabutyl ester of EDTA (Additive D). The mixture was stirred at 100150 F. for 6 hours at the end of which the NaOI-I was not completely consumed. The mixture was diluted with 14 grams of water and 100 mls. of 95% ethanol. After stirring overnight at room temperature the pH changed to 8 and the 14 powder. It showed the presence of 6.08% N and 12.9% Na, it apparently being a mixture of Bu YNa and BuYNa Y designating the EDTA ester radical.

EXAMPLE IV Thirty-eight liters of water and 8,160 grams of 96% H 80 were mixed in a 50 liter, 3-necked flask. The resultant solution was heated to 95 'C. and 2,920 grams (10 moles) of ethylene diamine tetraacetic acid were slowly added with constant stirring. The clear solution obtained was cooled to room temperature, whereupon the sulfuric acid salt of EDTA separated out as white crystals. The latter was separated by filtration and the filtrate was fortified with 1,000 grams of 96% H 50 and used for the preparation of another 10 moles of the sulfuric acid salt of EDTA. About 4,212 grams of the sulfuric acid salt were placed in a 50 liter, 3-necked flask and 16,700 grams of nbutanol were added. The mixture was stirred and refluxed for a period of 62.5 hours, during which time a total of 2,215 ml. of water were collected from the Dean- Stark trap.

About 1,000 grams of the reaction mixture was charged into a 5-liter, 4-necked flask and neutralized with 10% Na CO The organic layer was washed twice with 5% Na CO and three times with distilled water. The washed solution was topped at 1 mm. to 120 C and filtered through Hyfio Super-Cel. There was obtained 335 grams of light yellow clear liquid giving the following analysis: C, 59.53%; H, 9.30%; N, 4.85%; Na, 0.525%.

Since pure monosodium salt of the trim'butyl ester of EDTA (Bu YNa) contains 4.77% Na, this is equivalent to a 11% solution of the salt in tetra-n-butyl ester of EDTA (Bu Y).

After using 4,000 grams of the reaction mixture for similar purposes, the rest of it was neutralized with 10% K CO The organic layer was washed twice with 5% K CO and three times with deionized water. The washed solution was topped to 120 C. at 3 mm. and filtered through Super-Cel. There was obtained 4,745 grams of light yellow clear liquid showing the following analysis: C, 59.48%; H, 9.27%: N, 5.33%; K, 0.784%.

Since pure Bu YK should contain 7.83% K, the present product is a 10% solution of Bu YK in Bu Y.

EXAMPLE V The following additives identified in Table 1 below were prepared utilizing the general procedures described in Examples I-III above. The inonosalts Bu YK, Bu YNa, (n-C H )YNa, (n-C H l YNa in the table and the ex amples to follow are based on the theoretical amounts of alkaline solution required to give the monosalt and may contain small amounts of the diand tri-salts as byproducts.

TABLE IV Additive Salt Designation Percent 0 Percent II Percent N Percent Na Percent K Composition Estimated 5. 21 0. 207 3.78% BugYK in End. 5. 36 0. 489 10.20% BugYNa in Bu Y 5. 31 (1. S16 17.1% Bu YNa. in Bu Y. 5.16 0. 500 10.7% BlJaYNtt in IillqY. 4. T6 t]. 244 3.11% IiuaYK in ButY. 5. 43 4.47 03.8% BusYNa in ButY. 5.15 4.07 IlugYNa.

5. 40 1. 76 36.0% BusYNa in Bun. 4. 75 3. (n-CsIInhYNu.

5. 23 4. 28 (n-(ltllnltYNa.

5 (l0 0 (J Distilled llutY.

mixture was vacuum stripped at 100 C./2 mm. and filtered to give 70 grams of clean, yellow gel-like product. It contained 5.15% N and 4.97% Na, the theoretical value calculated for Bu YNa being 5.81% N and 4.77% Na. The solid product remaining on the filter was washed EXAMPLE VI Samples of ester based fluids containing either additive A, B or D, all identified above together with phenylot-naphthylamine (PAN) were subjected to an oxygen with n-hexane and dried to give about 4 grams of a white absorption test. To demonstrate the detrimental effect of iron and the effectiveness of our additives in overcoming it, 12 ppm. Fe was added as iron octoate. PAN

l6 fluids identified in Table VI below and the blends were subjected to the oxygen absorption test. Samples of the TABLE V! 0011011., 02 Absorption Test Data Base Fluid Additives Wt.

percent Ti Ti Vi V:

min. min. ml. ml. Frirlmulation 0.1 13 Trimethylol-propane tripelargonate-.. PAN 1% 138 187 1, 371 2,500 14 ..d 53; 1 40.5 92 282 2,500

PAN- 15 do Fe 12 289 330 1,124 2, 500

Additive A 1% 16 TMP C-C0 PAN 1% 111 157 512 2,500

17 TMP C0-C0 82. 5 256 2,500 18 TMI C0-C0 u 12 451 1,223 2, 500 Ester FluidA i' 5 97.5 133 512 2, 500

PAN 1% 20 "do! Fe 12 369 423 1,125 2,500

00 c 1 E t I ggtm BM 1% omp ex s er 1'7 21 "izo y'j Dioctyl azelate F a 12;} 7

807 Complex Ester 1 1 22 F Hi0? 112 162 895 2.500 23 Dioctylsebaeate 5 32 92.5 158 2,500

1 o 25 Pentaerytlu'itol tetravalerate N 5 84 127 371 2,500

PAN 1% 20 ..do Fe '12 500 562 1,525 2,500

Additive B 1% 27 Dipentaerythritol hexahutyrate. 183 411 2, 500

PAN 1% 28 .do Fe '12 773 788 2,150 2, 500

Additive G 1% l Ester oi aikanoic acids and trlmethyiolpropane. 2 Complex ester prepared from 1 mole neopentyl glycol, 2 moles atelaie acid and 2 moles isooctyl alcohol.

5 Pounds per minute.

alone or additive A alone were also tested for comparison.

TABLE V base fluids with PAN along, with or without iron were also tested. The results are shown in Table VI.

0: Absorption Test (450 F.)

Base Fluid Additives Concn., Ti, T8, Vi, Vt,

Wt. min. min. ml. m1. percent ,qorrnulation No.: HA 5 5 41 2 500 1 one 2.- HA 1.5 300 351 758 2,500

1 1 189 231 450 2,500 e HA-....{ 1 None 831 2,500 9 PE-CQH i 202 241 498 2,500 A 10 PE-C@--{ 1 917 038 1,000 2,500 "{;"'}PAN 1 111 157 512 2,500

TMP .PAN 1 12 C O AdditiveB 1 415 820 HA essentially complete pentaerythritol ester of fatty acids having an average of 7 carbon atoms and with the following inspection data: Acid No., 0.01; Saponification No. 410;

Viscosity at 210 F., 6.10 cs.; Viscosity at 100 F. 25.0 cs.

PECr=Penta-erythritol tetracaproate.

TMP Cr-C =oster oi trimethyiolpropane and mixture oi C to C alkanoic acids.

1 Not reached at end of 416 min. when test was discontinued. 2 Pounds per minute.

EXAMPLE VII Additives A, B, C and D of the invention, identified above, together with PAN were added to various base The data of Table VI shows the effectiveness of the additive combination of the present invention in various ester-based fluids.

EXAMPLE VIII Additives A, B and C in combination with phenothiazine, di-or-naphthylarnine and a commercial aromatic amine A, respectively, in base fluids identified in Table 75 VII below were subjected to the oxygen absorption test.

17 Runs on phenothiazine alone with and without iron are included. The results are reported in Table VII and demonstrate the effectiveness of the alkali metal salts of the invention in combination with either phenothiazine, di-wnaphthylamine or the aromatic amine A.

18 As the data show, tetra-n-butyl ester together with PAN provides a relatively ineffective additive combination.

EXAMPLE X To base fluid HA containing 12 ppm. Fe as iron TABLE VII Cnc., 0: Absorption Test Base Fluid Additives W Percent Ti Tt Vi Vt Formulation No.:

29 Plexol 201, 85%;Acry1oid HF 820,"%.. Phenothiazlne 0.5 96 13B 575 2,500 30 o f*f {f P 2 42 325 2.500

Phenothiazine 0. 5 31 do Fe i 12 112 167 725 2, 500

Addit 1.0 Di-a-naphthylami 1 32 HA Additive 0-... 1 192 192 r 461 Fe I 12 Aromatic amine A 1 33 HA Ad tiveB 1 293 293 782 1 A diethylhexyl sebacate oil having a kinematic viscosity at F. of 12.3 cs., a viscosity index ot154, a pour point below 80 F.

and acid N o. oi 0.12. a A polymethacrylatc. 3 Identified in Table V.

EXAMPLE IX Compositions composed of:

Ester base fluid HA percent Parts per million.

octoate and 1% PAN was added 0.5% of additives I, I and K identified in Table IV above. The samples were all subjected to the oxygen absorption test. The results as shown in Table IX illustrate the effectiveness of salts Additive as indicated in Table VIII do +1 of higher alkyl esters of EDTA Fe p.p.m 12

TABLE IX Additive Amt. 02 Absorption Test Data Designation Formula Used Wt.

Percent Ti Tt Vi Vt Formulation No.:

41 I (II-CsHiflaYNB. 0- 5 543 573 1,320 2, 500 J (n-CaI-InhYNa- 0. 5 B20 841 1,532 2, 500 K (nC5H1|) YNa 0. 5 None 1,197 2, 500

EXAMPLE XI One of the most severe screening tests for high temperature synthetic lubricants is the Erdco High Tempera- 40 ture Bearing Rig Test. Under the Type II conditions specified by Pratt and Whitney, the test lubricant must have a viscosity rise (or KV/ 100 F.) of less than 100%, preferably less than 30%, after 100 hours at a bearing temperature of 500:5 F. The dirtiness of the bearing 45 head after test, as expressed by a WADD demerit rating,

should be less than 100. Table X shows the eifectiveness TABLE VIII Cone. of 0: Absorption Test Data Additive Wt. Na Salt as Use Percent BuaYNa, Designation Wt. Percent Ti Tt Vt Vt Cale ated Formulation No.:

34 D 0.5 0 0513 108 794 2,500 O 0.5 0 0854 208 1,050 2,500 C 1.0 0 1708 360 306 2,200 2,500 0 0.2 0 20 368 397 1,100 2,500 F 0.3 0 28 None 470 ,050 H 1.0 0 369 005 614 2,176 2,500 L 1. o 0 47. s 93 2, 500 l The data of Table VIII demonstrate the importance of the alkali metal salt in obtaining an efiective additive.

of the present inhibitor system as indicated by the hearing head test.

TABLE X.ERDCO HIGH TEMPERATURE BEARING RIG TEST Bearing Temperature, 500:50. 011 in Temperature, 400: 10 F. 011 Sump Temperature, 440:5 F. Duration, 100 hours Wt. KV/100, WADD Final Base Fluid Additive Percent Percent Demerit Acid Rating No.

Test No 1 HA FAN 1 2,190 128 9. 93 2 HA --{Ala'v''i11:; 1 291 38 W s TMP-c. 122 90 4.12 4 Pentaerythritol tetravelerate..{g 14. 6 B5 0.30

l Tricaprylate of trimethylol propane.

20 EXAMPLE XIII Samples of an ester based fluid containing either phenylu-naphthylamine (PAN), the sodium Salts identified in the Table below, or a combination of phenyl-a-naphthylamine and sodium salt were subjected to the oxygen absorption test described above. The results of the test are reported in the following Table XII.

TABLE XII Wt. Absorption 'Iest Base Fluid Additives Percent T Tl W W None 73 2,500 ggg j 8 ,1 5 ,310 2,500 6 ..d0 Na 4=thiad0decan0te 1.1 None 84 2,500 7 do PAN 440 487 1240 2500 Ne 4-thiadodecan0at0 0.1 s ..do 1;: or Geigy inn-281 1 138 131 743 2,500 9w ""{Nasaltbifieigyltilj 011} 878 L160 10 do Na acetylaeetonate. 1.1 None 81 A--. 2, 500 PA 9} 1,117 1,141 1,450 2,500 PAN None 00 2,500 "{NaBu;(ED'IA). 011} 896 1,470

Conditions=405 F., 1 it. /hr. 0! 0 and g. sample. l IIercolube A- (identified in Table I). 2 PAN N-phenyl-a-naphthylamine.

2. l EDTA is ethylenedlaminetetraacetic acid. In making this lubricant sample, g. of Hercolube A was blended with 11 g. of additive D identified in Table IV above.

EXAMPLE XII The lubricant system of the present invention comprising Base Fluid HA, described above, 1% by weight phenyl-a-naphthylamine and 1% by weight of Additive A was subjected to a modified MILL9236 corrosionoxidation test run at 450 F. for a period of 48 hours. The data reported in Table XI were obtained. The test was conducted by passing a stream of air at the rate of 5 liters per hour through ml. of the sample and one inch square coupons of copper, steel, magnesium, aluminum, silver and a titanium alloy. Acid number and viscosity were determined on the centrifuged oil. Results are shown in Table XI.

The data of Table XII demonstrate the enhanced antioxidant properties provided synthetic fluids by the combination of PAN and various sodium salts of the invention.

EXAMPLE XIV 1 Identified in Table I above.

Ti Alloy .I

The data of Table XIII clearly show that the combination of sodium octyl phenate with either calcium cetyl phosphate or amyl lactate provides, in both instances, an ineffective antioxidant system in ester-type lubricants at elevated temperatures (e.g. 450 F.).

It is claimed:

1. A normally liquid lubricating oil composition consisting essentially of a major amount of a normally liquid carboxylic acid ester base oil of lubricating viscosity having dissolved therein amounts from about 0.005 to 5 weight percent of an ester base oil soluble alkali metal organic compound selected from the group consisting of:

alkali metal salts of fluorinebromineor iodine-containing monocarboxylic acids,

alkali metal salts of chlorine-containing lower fatty acids,

alkali metal salts of phenols having 7 to about 24 carbon atoms and containing one or more alkyl or amido substituents,

alkali metal salts of aliphatic ketones having about 5 to 22 carbon atoms,

alkali metal salts of Schilfs bases having about 4 to 30 carbon atoms and which are condensation products of aldehydes or ketones with primary amines,

alkali metal salts of sulfur-containing monocarboxylic acids having the formula:

a(- -o-)mn'..-srt'-c 0 0H wherein R is alkyl of 6 to 20 carbon atoms, R is alkylene of l to 8 carbon atoms, m is 0 or 1. n is 0 or 1, and m equals n, and alkali metal salts having the formula:

wherein M is an alkali metal, R is a non-olefinic, non-acetylenic hydrocarbon radical having on the average about 3 to 18 carbon atoms and Z is an alkylene radical of 1 to 20 carbon atoms;

and from about 0.05 to 5 weight percent of an ester base oil soluble aromatic amine having the general formula:

wherein Q is a non-olefinie, non-acetylenic, monovalent hydrocarbon radical of 1 to 20 carbon atoms and Q is a non-olefinic, non-acetylenic aromatic hydrocarbon radical of 6 to 16 carbon atoms, said amounts being effective to retard oxidation of said ester-based fluid at a temperature of 450 F.

2. The lubricant composition of claim 1 wherein the alkali metal is sodium.

3. The lubricant composition of claim 1 wherein said alkali metal organic compound is an alkali metal salt of 4-thiadodecanoic acid.

4. The lubricant composition of claim 1 wherein the ester base oil is a fatty acid ester of an alkanol haying the general formula:

wherein n is 0 to 1 and R is selected from the group consisting of a lower alkyl radical and hydroxy lower alkyl.

5. The composition of claim 1 wherein the ester base oil is an ester of an alkanol of 4 to 12 carbon atoms and an alkane carboxylic acid of 4 to 12 carbon atoms.

6. The lubricant composition of claim 1 wherein said alkali metal compound is an alkali metal salt of a chlorine-, fiuorine-, bromineor iodine-containing lower fatty acid.

7. The lubricant composition of claim 6 wherein the halogen is fluorine.

8. The lubricant composition of claim 6 wherein said halogen-containing lower fatty acid is a perfiuoro acid.

9. The lubricant composition of claim 6 wherein said halogen-containing lower fatty acid is trichloroacetic acid.

10. The lubricant composition of claim 6 wherein said halogen-containing lower fatty acid is perfiuorobutyric acid.

11. The lubricant composition of claim 10 wherein the alkali metal is sodium.

12. The lubricant composition of claim 11 wherein the lubricant also contains a tetraalkyl ester of ethylene diamine tetraacetic acid, said alkyl ester groups having an average of 4 to 8 carbon atoms and said ester being present in a small amount sufficient to enhance the anticorrosive properties of the lubricant.

13. The lubricant composition of claim 1 wherein said dissolved alkali metal compound is added as a compound having the structural formula:

wherein M is an alkali metal and R is a non-olefinic, nonacetylenic hydrocarbon radical having on the average about 3 to 18 carbon atoms and Z is an alkylene radical of l to 20 carbons.

14. The lubricant composition of claim 13 wherein the alkali metal is sodium.

15. The lubricant composition of claim 13 wherein R is an alkyl radical of 4 to 8 carbon atoms, Z has 2 carbon atoms, Q is an aromatic radical, both Q and Q have 6 to 12 carbon atoms, M is sodium and the salt is a 3 to 40% solution in the tetraester of ethylene diamine tetraacetic acid in which the salt is made.

16. The lubricant composition of claim 1 wherein the aromatic amine is N-phenyl-a-naphthyl amine.

17. The lubricant composition of claim 16 wherein the alkali metal compound is present in the amount of about 0.01 to 2%.

18. The lubricant composition of claim 17 wherein the g pomatic amine is present in an amount of about 0.1 to

19. The lubricant composition of claim 18 wherein the alkali metal compound is sodium perfiuoro butyrate and the amine is N-phenyl-a-naphthyl amine.

References Cited UNITED STATES PATENTS 2,197,836 4/1940 Reitf et al. 252-400 XR 2,344,988 3/ 1944 Kavanagh et al. 252-42.7 XR 2,352,462 6/ 1944 Weiss et al 252400 XR 2,421,631 6/1947 Lincoln 25233.6 2,512,784 6/1950 Adelson 25233.4 2,680,094 6/ 1954 Bartlett et al. 25251.5 2,715,107 8/1955 Talley et al. 25242.7 XR 2,788,326 4/1957 Bondi et al. 25233.4 XR 2,805,203 9/1957 Knapp et al 25234 2,988,506 6/1961 Sproule et al. 25233.4 XR 3,121,691 2/1964 Eickemeyer 2525l.5

DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Assistant Examiner.

US. Cl. X.R.

22 3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. *3, l36,3 +8 Dated April 1, 1969 Imknmfls) Tai S. Chao, Howard J. Metson and Manley Kjoneas It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 7, the inventor's name, "Knonaas" should be --KJonaas-.

Column 5, line +3, "an" should be --and--.

Column 6, line 46, -"in" should be --is- Column 7, line 38, "his" should be --this--.

Column 10, TABLE II, the third line under the third column, reading "C4F C00Na" should be --C F C0ONa--.

Column 12, line 50, "one should be --on--;column 12, line 52, "men-salt should be --mono-salt--.

Column 16, TABLE VI, the twelfth line under the second column, "Fe should be --Addltive A", column 16, TABLE VI the twelfth line under the third column, 12" should be "1%"; column 16, TABLE VI, the ninth line under the fifth column, "7" should be --70--; columns 15-16, footnote 3 reading "Pounds per minute" should be --Pa.rts per million--.

Column 18, TABLE x, the fourth column heading "KV/lOO, Percent" should be AKV/lOO, Percent--.

Column 19, ABL XII, footnote "Conditi0ns=405F. should be --Conditions= l50F.--.

Column 21, in the formula in claim 4, "HCCH should be HOCH2- SIGNED AND sEAL) k EME WILLIAM E. JR- Commissions: Patents L I AUG 2 01969 u J Edwczd ill. Fletcher, In

"w Auwhng ul'flccr

Claims

1. A NORMALLY LIQUID LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A NORMALLY LIQUID CARBOXYLIC ACID ESTER HASE OIL OF LUBRICATING VISCOSITY HAVING DISSOLVED THEREIN AMOUNTS FROM ABOUT 0.005 TO 5 WEIGHT PERCENT OF AN ESTER BASE OIL SOLUBLE ALKALI METAL ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF: ALKALI METAL SALTS OF FLUORINE- BROMINE- OR IODINE-CONTAINING MONOCARBOXYLIC ACIDS, ALKALI METAL SALTS OF CHLORINE-CONTAINING LOWER FATTY ACIDS, ALKALI METAL SALTS OF PHENOLS HAVING 7 TO ABOUT 24 CARBON ATOMS AND CONTAINING ONE OR MORE ALKYL OR AMIDO SUBSTITUENTS, ALKALI METAL SALTS OF ALIPHATIC KETONES HAVING ABOUT 5 TO 22 CARBON ATOMS, ALKALI METAL SALTS OF SCHIFF''S BASES HAVING ABOUT 4 TO 30 CARBON ATOMS AND WHICH ARE CONDENSATION PROUCTS OF ALDEHYDES OR KETONES WITH PRIMARY AMINES, ALKALI METAL SALTS OF SULFUR-CONTAINING MONOCARBOXYLIC ACIDS HAVING THE FORMULA: