US3321402A

US3321402A - Lubricating composition

Info

Publication number: US3321402A
Application number: US462435A
Authority: US
Inventors: James G Dadura; Jr Jackson W Wisner; Morris A Wiley
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1965-06-08
Filing date: 1965-06-08
Publication date: 1967-05-23
Anticipated expiration: 1984-05-23
Also published as: GB1107162A

Description

United States Patent of Delaware No Drawing. Filed June 8, 1965, Ser. No. 462,435

14 Claims. (Cl. 252-47.5)

This invention relates to a lubricating composition designed for the lubrication of turbine engines which operate over a wide temperature range and under severe operating conditions. More particularly, this invention relates to a synthetic lubricating oil composition having good extreme pressure and superior non-corrosive properties.

Synthetic base lubricants of the ester-base type have been found to be very useful in meeting requirements for the lubrication of modern high performance turboprop, turbojet and turbofan engines. However, even these superior base components must be tailored to meet certain stringent engine performance requirements as set forth in appropriate specifications by the military and by commercial aircraft engine manufacturers. It is particularly difiicult to achieve a synthetic oil composition having all the desired properties to withstand extreme thermal and oxidative stress without becoming corrosive due to excessive oxidation of the components of the synthetic oil.

Dimerized fatty acids and mixtures of same containing trimer acid material have heretofore been employed to impart load carrying properties to synthetic lubricant compositions, see US. 3,048,542. Unfortunately, compounded synthetic lubricating oils containing dimer acids and their mixtures containing trimer acids material even in minute proportions tend to promote corrosion of copper, magnesium and lead with the result that synthetic lubricating oils containing same cannot meet the anti-corrosion specifications required for current synthetic lubricants. A synthetic lubricating oil composition has now been discovered which has superior non-c0rrosive properties while retaining a high level of load-carrying properties. When employed in a fully compounded oil, the resulting synthetic lubricating oil composition meets the severest performance requirements of todays jet engines.

The lubricating composition of this invention broadly comprises an ester-type fluid having lubricating properties containing a monoamide of an heterocyclic aromatic amine and a material consisting essentially of trimer acids produced by the condensation of unsaturated monocarboxylic acids having between 12 and 22 carbon atoms per molecule in an amount sufficient to impart excellent extreme pressure properties to the composition as well as superior anti-corrosion properties in a compounded oil. Generally, the monoamide is employed in an amount ranging from about 0.01 to 1.0 weight percent based on the weight of the lubricating oil composition.

The compounded lubricating oil composition will contain an oxidation inhibiting amount of an heterocyclic sulfur and nitrogen containing compound from the group consisting of orthothiazine, metathiazine, parathiazine, phenothiazine and their low molecular weight aliphatic derivatives, an oxidation inhibiting amount of an aromatic amine from the group consisting of naphthylamine, diphenylamine, phenylene diamine and their low molecular weight aliphatic and aromatic derivatives and a cor- "ice rosion inhibiting amount of a compound from the group consisting of quinizarin, alizarin, purpurxanthrene, anthrarufin and chrysazin. The compounded oil is still further improved with a corrosion inhibiting amount of sebacic acid. It is conventional to employ a viscosity index improving amount of an alkylrnethacrylate polymer in the lubricating oil. Dispersant type methac-rylate copolymers, such as those prepared from alkylmethacrylate and nitrogen containing vinyl monomers, are also advantageous. The low molecular weight aliphatic derivatives referred to above are those having from 1 to 8 carbon atoms in the alkyl radical and the low molecular weight aromatic derivatives are those having 6 carbon atoms in the aryl radical of the derivative.

The novel extreme pressure and loadcarrying additive of this invention is a monoamide of a polymerized polybasic acid. More particularly, this additive is a monoamide of an heterocyclic aromatic amine and a material consisting essentially of trimer acids produced by the condensation of unsaturated monocarboxylic acids having between 12 and 22 carbon atoms per molecule.

The heterocyclic aromatic amines from which the monoamide is prepared include the aminopyridines, dipyridylamines and the phenothiazines. Specific effective heterocyclic aromatic amines are Z-aminopyridine, 3- aminopyridine, 4-aminopyridine, 2,2'-dipyridylamine, 3,3- dipyridylamine, 4,4-dipyridylamine and phenothiazine.

Trimer acids are fatty materials produced by subjecting unsaturated fatty acids having between 12 and 22 carbon atoms per molecule, preferably about 18 carbon atoms, to condensation by moderate steam pressures of from to 300 p.s.i.g. at temperatures from 260 to 360 C. for a period of from about 3 to 8 hours. Processes for forming these acids are set forth in such patents as US. 2,482,761, 2,631,979 and 2,632,695. Another method for preparing the trimer acid mate-rials broadly comprises heating a short chain aliphatic alcohol ester of a diethylenic fatty acid at about 300 C. for several hours in an inert atmosphere. The resulting polymerized esters containing trimer acid material are then separated by distillation and hydrolyzed with hydrochloric acid or its equivalent. Fatty oils have also been heat polymerized and thereafter hydrolyzed to produce the polymer acids. The trimer acid is readily separated by distillation or by a solvent extraction process from the monomeric, dimeric and higher polymeric materials usually co-produced in the foregoing methods.

The trimer acids used in the present invention, although preferably conjugation products of three of the same molecules which are dior polyethylenic, are also products of the combination of monoethylenic compounds and polyethylenic compounds, for instance, linoleic acid and oleic acid trimerizer to become the trimer of linoleic and oleic acids. It is essential to have at least one polyethylenic compound present in order to form the trimer acid.

Specific fatty acids useful for preparing trimer acid from the class of ethylenic carboxylic acids having from 12 to 22 carbon atoms include 4-dodecenoic, 5,9-dimethyl- 2,8-decadienoic, myristoleic, palmitoleic, oleic, linoleic, linolenic and erucic acid. The preferred acid is linoleic acid on the basis of availability from which is produced the preferred trimers of linoleic acid. These particular trimer acids are producer commercially under the name Emery 3162D by Emery Industries. All of the above acids are generally obtainable by hydrolyzing vegetable oils, such as linseed oil, soy bean oil, cotton seed oil, and peanut oil.

One method for preparing the monoamide is by reacting equivalent mole ratios of trimer acid and the heterocyclic aromatic amine. Since trimer acid is tribasic and the noted amines are monofunctional with respect to amide formation, the proportions indicated produce primarily the monoamide. The two compounds are reacted by refluxing in xylene so as to maintain a reaction temperature of about 380 to 390 F. while the water formed is removed during the reaction. When the reaction is complete, the xylene is stripped off under reduced pressure. Specific examples of the preparation of monoa-mides of this invention are given below:

Example 1 36 g. (0.3 mole) of thionyl chloride was added slowly to 96 g. of a mixture of polymerized linoleic acid containing 48 percent of the trimer of linoleic acid. Upon completion of the addition, 100 ml. of toluene was added and the mixture heated at reflux temperature for 45 minutes to drive off volatile reaction products. 32 g. (0.16 mole) phenothiazine was dissolved in 300 ml. toluene in a second vessel. The reaction product of the acid and thionyl chloride was added slowly with stirring and the mixture heated to reflux temperature. The solvent and volatile materials were evaporated under vacuum at 140 F. in a rotary evaporator. The crude reaction product was dissolved in toluene, treated with 20 g. activated charcoal, filtered and stripped at 200 F. and a pressure of 16 mm. of mercury absolute. The resulting 98 g. of the amide of phenothiazine was identified through infrared absorption.

Example 2 420 grams of the trimer acid of linoleic acid, Emery 3162D (1.5 equivalents) and 47 grams of Z-aminopyridine (0.5 equivalent) were refluxed in xylene for 24 hours at 370 F. and 9.5 ml. of water was taken off. The product was then stripped at 400 F. under mm. of pressure. The recovered monoamide of trimer acid and 2-aminopyridine had a Total Acid No. of 112 and was found to contain 2.9% N as compared to a theoretical composition of 3.07% N.

Example 3 840 grams of the trimer acid of linoleic acid (3.0 equivalents) and 94 grams of Z-aminopyridine (1.0 equivalent) were refluxed in xylene for 19' hours at 387 F. and 19.5 ml. of water was taken off. The product was stripped at 400 F. under 15 mm. of pressure. The recovered monoamide of trimer acid and Z-aminopyridine had a Total Acid No. of 116 and was found to contain 3.0% N as compared to the theoretical N content of 3.07%.

The foregoing novel E.P. agents are employed in the lubricating oil compositions in concentrations ranging from about 0.01 to 1.0 weight percent. The preferred amounts of the BF. agents are from about 0.05 to 0.2 weight percent.

Phenothiazine is a preferred primary anti-oxidant and anti-corrosive agent for lubricating oils having the formula:

Other effective anti-oxidants of this class include orthothiazine, metathiazine and parathiazine. They inhibit corrosion by preventing oxidation of components of the lubricating composition to acidic bodies which are inherently corrosive. The thiazine compound is generally employed in a concentration of 0.1 to 2 weight percent of the lubricant composition with the preferred amount being from about 0.4 to 1.5 percent.

An amine from the class of aromatic amines having anti-oxidant or antiozonant properties is also employed in the fully compounded lubricating oil composition. These aromatic amines are naphthyla-mine, diphenylamine, phenylene diamine and their C to C alkyl and C aryl derivatives. Particularly effective aromatic amine antioxidants are dioctyldiphenylamine and phenyl-l-naphthylamine. Other effective aromatic amines include N- phenyl-p-phenylene diamine, N,N'-diphenyl-p-phenylene diamine, N,N' -bis-(octylphenyl)-p-phenylene diamine, p-hydroxydip-henylamine and its esters, N-phenyl-N-isopropyl-p-phenylene diamine, N,N'-dioctyl-p-phenylene diamine. The amines are employed in amounts ranging from about 0.1 to about 4.0 percent by weight of the lubricant composition with the preferred proportions ranging from about 0.5 to 3 percent.

Another class of anti-oxidant and anti-corrosive agents a member of which is employed in the finished lubricating oil composition includes quinizarin, alizarin, purpurxanthrene, anthrarufin and chrysazin. The preferred agent, quinizarin, has the formula:

A member of this class is particularly effective to enhance low copper corrosion properties in the lubricating composition. These components are effective in a relatively small concentration ranging from about 0.01 to 0.5 percent with the preferred range being from about 0.05 to 0.2 percent.

Sebacic acid is a useful corrosion inhibiting additive which is advantageously employed in the lubricating oil of this invention. Sebacic acid imparts substantially improved corrosion resistance to the lubricants particularly with respect to the metal, lead. Sebacic acid imparts this property in surprisingly small concentrations in the lubricant ranging from about 0.0001 to 0.1 percent and preferably from 0.001 to 0.05 percent.

Methacrylate polymers are well known V.I. improvers and por point depressors. Polyester base luubricants, al-

though they, per se, possess excellent V.I. and pour, often require the presence of small concentrations of methacrylate polymers to improve dispersancy and meet the requirements of military specifications. These methacrylate polymers are usually copolymers of two or more esters of methacrylic acid and usually have a molecular weight between 5000 and 20,000. The met'hacrylate esters have the following general formula:

wherein R is an aliphatic radical preferably ranging from butyl to stearyl.

Copolymers which find particular use as V.I. improvers and pour point depressants are the following: a copolymer wherein R in the above formula comprises 20% lauryl, 40% octyl and 40% 'cetyl; a copolymer wherein R in the above formula is 50% stearyl and 50% lau1yl; a copoly mer wherein R in the above formula comprises 50% lauryl and 50% octyl.

Methacrylate polymers are usually sold in the form of a concentrate comprising approximately 20 to 50% polymer in a carrier oil. For the lubricant compositions of this invention, it has been found advisable to use an ester-type carrier oil, such as dioctylsebacate or trimethylolpropane tripelargonate, rather than the usual mineral base lubricating oil. The use of a methacrylate ester in an ester-type barrier oil has proven particularly effective in meeting the low temperature and viscosity requirements of military specifications. Dispersant type methacrylate copolymers, for example Acryloid HF-866 manufactured by Rohm and Haas, containing nitrogen func tional groups, such as vinylpyrrolidone and dimethylaminoethylmethacrylate are particularly elfective and are described in U.S. Patents 3,142,664, 3,147,222 and 3,153,- 640. Methacrylate polymers can constitute 0.1 to 20 weight percent of the composition but ordinarily are used in a concentration between 0.25 and weight percent.

A commonly used ester base lubricant is an aliphatic diester of an organic dicarboxylic acid. The dicarboxylic acid component is usually an aliphatic dicarboxylic acid containing 6 to 12 carbon atoms but glutaric acid esters and succinic acid esters may also be used. From the standpoint of cost and availability, the preferred dibasic acids are adipic acid, sebacic acid and azeloic acid. The aliphatic alcohols use-d to form the diesters usually contain at least 4 carbon atoms and may contain 20 or more carbon atoms although C to C alcohols are preferred. Ether alcohols, such as Cellosolve, Butyl Cellosolve and Carbitol may also be used in the formation of the allphatic diesters of organic dicarboxylic acids used as the lubricating base in the compositions of this invention.

Specific examples of the dialkyl esters of aliphatic dicarboxylic acids are as follows: di-isooctyl azelate, di-2- ethylhexyl sebacate, di-Z-ethylhexyl azelate, di-2-ethylhexyl adipate, dilauryl azelate, di-sec-amyl sebacate, di-2- ethylhexyl alkenylsuccinate, di-2-ethoxyethyl sebacate, di- 2-(2'-methoxyethyoxy) ethyl sebacate, di-2-(2'-ethylbutoxy) ethyl sebacate, di-2-butoxyethyl azelate, di-2-(2- butoxyethoxy) ethyl alkenylsuccinate, etc.

In addition to the aliphatic dicarboxylic acid esters described above, polyester and complex ester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a glycol and a monofunctional compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, in specified mole ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in U.S. 2,628,974, Complex esters formed by reaction of a mixture containing specified amounts of 2-ethyl-1,3- hexanediol, sebacic acid and 2-ethylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and Z-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

Polyesters formed by reaction of a monocarboxylic acid and a glycol or polyol may also be used as the ester component. The acid component is usually an aliphatic acid containing 3 to 20 carbon atoms and preferably 4 to 10 carbon atoms. The glycol or polyol component is advantageously a straight glycol, such as 1,5-hexanediol, but ether glycols, such as tetraethylene glycol, may also be used. Sterically hindered neopentyl type glycols, such as 2-methyl, 2-ethyl, 1-3, propanediol, are favored for enhanced thermal stability.

Specific examples of the diesters of glycols are the following: di-n-decanoate of 1,4-butanediol, di-Z-ethylhexanoate of 1,6-hexanediol, dilaurate of 1,4-hexanediol, dioctanoate of 1,5-pentanediol, dilaurate of tetraethylene glycol, dilaurate of triethylene glycol, dioctanoate of pentaethylene glycol. Examples of triesters are trimethylolpropane triheptanoate, trioctanoate and tripelargonate. Examples of tetraesters are pentaerythritol tetracaproate and pentaerythritol and dipentaerythritol esters with mixtures of aliphatic acids containing three to ten carbon atoms.

Complex esters formed by reacting trimethylol and tetramethylol alkanes with various mole ratios of dibasic acids and monobasic acids or alcohols are other examples of polyesters useful for the base fluid of the lubricants of this invention. Pentaerythritol tetraesters of C aliphatic carboxylic acid are a preferred class of polyester lubricating oils.

The sulfur analogs of the above-described esters are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-Z-ethylhexylthiosebacate, di-n-octyl thioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and 2-ethylhexyl mercaptan.

Other additive components can be advantageously incorporated in the lubricant composition of the invention. For example, an anti-foam agent such as a hydrocarbon or kerosine concentrate of dimethyl silicone in an amount ranging from about 0.0001 to 0.01 percent by weight is generally added to the lubricating oil. Detergents, such as the metal salts of phenates and sulfonates, are also widely used dispersants. In particular, barium sulfonates have been found useful since they inhibit corrosion and rusting.

The lubricating composition of the invention was tested for its anti-corrosive, and ER properties in a 400 or 425 F. Oxidation-Corrosion Test, a Lead Washing Test, an SOD Lead Corrosion Test and in the Ryder Gear Test.

The 425 F. Oxidation and Corrosion Test is conduct ed in accordance with Method 5308.4 of Federal Test Method Standard No. 791a (issued Dec. 31, 1961) except for the following modifications to conform to Pratt & Whitney Aircraft Specification 5213 (Type II). The bath temperature is maintained at 425 F. plus or minus 1 F. instead of at 250 F. This test is conducted for a period of 48 hours instead of 168 hours specified in the original test. Copper corrosion, as evidenced by a weight change of greater than $0.30 mg./cm. Cu, is considered a failure and cause for rejection.

The Lead Washing Test is a method intended for the determination of the tendency of a jet engine oil to remove lead flashing from ball bearing cages and/or to attack silver plating beneath the lead. Ratings in this test correlate with airline service experience and with the Texaco-United Airlines Jet Engine Simulator Test using bearings, gears and seals from a Pratt and Whitney 1T3 C-6 model engine. This test is run with a sample of 800 mls. with 3 liters of oxygen per hour being bubbled into the sample. The sample is agitated with a stainless steel stirrer at 300 r.p.m. Lead and silver test panels are introduced. This test is usually run for a l68-hour period. At the termination of the test, the metal panels are Weighed after naphtha Washing and air drying and then weighed again after rinsing and Wiping with orthodichlorobenzene, rinsing with a 50-50 volume mixture of acetone and ASTM precipitation naphtha followed by air drying.

Outline 0 procedure (1) A stirrer is prepared by cutting an 18 gage (0.0500) stainless steel disc 1 /4 in diameter into 4 segments with the cuts extending to Within A" of the center. The segments then formed are bent to 30 to form a four-bladed propeller. The propeller is then mounted on a A" diameter stainless steel shaft approximately 9 /2" long.

(2) One lead panel is prepared from a four pound lead sheet" 4 thick) conforming to ASTM B 29-55 Chemical Lead grade. The panel is by 1%" by 1%" and has a diameter hole in the center.

One silver panel is prepared from soft fine electrolytic silver sheet approximately 0.030 inch thick. The panel is 1 inch square and has a /s inch diameter hole in the center.

(3) Clean the lead and silver test panels by rubbing with No. steel wool to produce a uniform bright finish over the entire surface of the faces and edges of each panel. Swab panels with a clean cotton pad wetted with precipitation naphtha, rinse with fresh naphtha and air dry. (Note: The panels are not to be touched with bare hands after the start of the cleaning operation.) Weigh each panel to the nearest 0.1 milligram and record the weights.

(4) Place a 1,000 ml. tall form beaker containing 800 ml. of test oil into a bath preheated to 250 F. so that the test oil level is at least 1" below that of the bath oil.

(5) Hang the lead and the silver panels midway in the oil at opposite sides of the beaker. Insert the stirrer to within /2" of the bottom of the breaker and by suitable means rotate it at 3003125 rpm.

(6) After the specified test period the metal panels are removed from the test oil.

(7) Rinse panels in a 50/50 volume mixture of ASTM precipitation naphtha and acetone, air dry and weigh to the nearest 0.1 milligram. This is the rinsed Weight.

(8) With a cotton swab soaked in 50/50 naphtha/acetone, wipe off most of any deposit from the panels. Wipe panels again with a cotton swab soaked in orthodichlorobenzene attempting to wipe off any deposit remaining. Wipe panels again with a fresh cotton swab soaked in 50/ 50 naphtha/ acetone followed by a rinse in fresh 5 0/ 50 naphtha/acetone, air dry and weigh. This is the wiped weight. Lead corrosion evidenced by a weight change greater than $6.0 mg./in. determined either before or after wiping, fails to pass this Lead Washing Test.

The SOD Lead Corrosion Test which is described in military specifications, MIL L-7808C, Lubricating Oil, Aircraft Turbine Oil, Synthetic Base, dated Nov. 2, 1955, was used to determine the corrosion resistance of lubricating oil compositions of the invention.

The SOD Lead Corrosion Test consists of exposing a lead specimen to the action of a test lubricant for one hour at 325 F.- :2 F. in the presence of a copper catalyst. The test lubricant is mechanically stirred and filtered dry air is introduced into the test lubricant at a controlled rate. Results are presented as change in weight (mgs.) per square inch of lead specimen surface area.

The Ryder Gear Test which is intended for the evaluation of a scuff-limited load-carrying ability of those lubricants used in reduction and accessory drives of turbojet and turboprop engines is described in US. 3,048,542.

Base Fluid A employed in the examples below is pentaerythritol tetracaproate. It is prepared from purified pentaerythritol and a mixture of C monobiasic acids. This base fluid has the following properties:

Viscosity, cs. at 210 F. 4.59 Viscosity, cs. at 100 F. 21.3 Viscosity, cs. at 40 F. 4788 Viscosity index 129 Flash, F. 490

This fluid has an 131 value of 1710 lb./in. as determined by the Ryder Gear Test.

Base Fluid B is technical grade pentaerythritol esterified with a mixture of 38 percent valeric, 13% Z-Inethylpentanoic, 32% octanoic and 17% pelargonic acids. This base fluid has the following properties:

Viscosity, cs. at 210 F 4.93 Viscosity, cs. at 100 F 25.6 Viscosity, cs. at 40 F 7023 Viscosity index 131 Flash, F 490 Ryder Gear, lb./in 2040 8 Base Fluid C is purified pentaerythritol esterified with a mixture of 1 percent butyric acid, 92 percent valeric acid, 4 percent caprylic acid, 1 percent pelargonic acid and 2 percent capric acid. This base fluid has the following properties:

Viscosity, cs. at 210 F 3.80 Viscosity, cs. at 100 F 17.62 Viscosity, cs. at 40 F 34.38 Viscosity, cs. at 64 F. (extrapolated) 21,000 Pour, F 75 Melting range of frozen oil, F -30 to -15 Ryder Gear, p.p.i 1305 Ryder Gear, relative percent 47 Base Fluid D is trimethylolpropane esterified with a monobasic acid mixture consisting of 2% valeric, 9% caproic, 13% heptanoic, 7% branched chain octanoic,

3% capryllic, 65% pelargonic and 1% capric acids. This base fluid has the following properties:

Viscosity, cs. 210 F 4.29 Viscosity, cs. at 100 F 19.98 Viscosity, cs. at 40 F 3638 Pour, F 75 Cloud, F Flash, F. 480 Fire, F. 545 Evaporation, percent, 6 /2 hr./400 F 4 Ryder Gear Test, lb./in. 2420 Ryder Gear Test, relative rating, percent 88 Base Fluid E is trimethylolpropane tripheptanoate and has the following properties:

Viscosity, cs. at 210 F 3.46 Viscosity, cs. at 100 F 15.8 Viscosity, cs. at 65 F 14,900 Flash, F 90 Flash, F 460 Fire, F 520 Evaporation, percent, 6 /2 hr./400 F 6 Base Fluid F is his (Z-ethylhexyl) sebacate, having the following properties:

Viscosity, cs. at 210 F 3.34 Viscosity, cs. at F 12.91 Viscosity, cs. at -40 F 1470 Viscosity, cs. at 65 F 8583 Pour, F 75 Cloud, F 80 Flash, F 445 Fire, F 500 Evaporation, percent, 6 /2 hr./400 F 18 Ryder Gear Test, lb./in 1960 Ryder Gear Test, relative rating, percent 77 Base Fluid G is his (tridecyl)sebacate.

Base Fluid H is his (2,2,4-trimethylpentyl) azelate.

The composition of the ester base lubricating compositions and their corrosion and BF. properties are given in the tables below. The amounts of the additive components in the lubricating compositions are given as percent by weight. Acryloid A consists of butyl, lauryl and stearyl methacrylate vinylpyrrolidone copolymer in trimethylpropane triester as carrier (50% active polymer). Acryloid B consists of a higher molecular weight version of Acryloid A in the same carrier (30% active polymer). Acryloid HF866 is a dispersant type polymer in dioctyl sebacate solution manufactured by Rohm and Haas.

Acryloid C is the same as Acryloid A except that the carrier is Base Fluid F.

TABLE I Lubricating Oil Blend Blend A Blend Blend D Blend E amide Sebacic Acid.. Quinizarim.

Dimer Acid (Empol 1 0.05 0.05 Antifoam concentrate (10% si icone),

p.p.m 100 100 100 100 100 Tests:

Kin Vis, 100 F., cs 26.1 25.8 26. 4 28. 5 28. 5 TAN, mg. KOH/g 0.12 0. 28 0.11 0.19 0.24 Ryder Gear Test, 1b./1n 2730 2585 2570 2710 425 F Oxid-Cort Test, 48 h 100 F. Vis. Inc, percent 30. 3 25 40 41 39. 4 TAN, mg. KOH g 2.0 2.16 1.86 1.34 1163 Metal wt. Change, mg./cn1. Cu 0.40 -0. 21 1.48 -0. 43 0. 29 Lead Washing Test, 250 F.:

Duration, hrs 168 168 168 168 336 Pb Wt. Change- Before wiping, mgJin. +41. 0 +0. 5 +9. 6 +0. 4 +0. 26 After Wiping, mg./in. +40. 0 +0. 2 1. 1 -1. 2 -0. G SOD Lead Corrosion, mgJin. 5. 5 -1.0 +0.8 0 4 Lubricating Oil Blend Blend F Blend G Blend H Composition wt. percent:

Base Fluid B Acryloid (HF-866).. Phenothiazine Dioetyldiphenyl amine. ZAmino-Pyridine Amide of trimer acid Phenothiazine amide of trimer acid- Quinizarin.

Scbacic acid Antifoam concentrate (10% Tests:

Appearance Kin Vis at 100 F. cs. Kin Vis at 210 F TAN, mg KOH/g Oxid-Corr. Test Percent V is at 100 F. Inc TAN Metal Wt. Change:

Cu. Mg, crn Fe, Al, Mg, Ag SOD pb Corr. mg./in.

325 F./1 hr 375 F./5 hr Lubricating Oil Blend Composition, Wt. percent:

Acryloid B s, cs., 40 F Total Acid No. (ASTMD-664).. SOD Lead Corrosion on 0 090 139 9:99 953 5: v

mww ro 00010.10 ovw o l V 10.20:: HOOD H00 00 0| I I |1| TABLE I-Continuecl Lubricating Oil Blend Blend 1 Blend .T Blend K Blend N Oxidation-Corrosion Test 400 F./72 hr. 400 F./72 hr. 425 F./72 hr. 400 F./48 hr. 425 F./48 hr.

Metal Wt. Change, mgJsq. crn.:

Cu 0. 22 0. 55 +0.02 +0.07 -0. 09 Fe, Al, Mg, Ag 0.0 0. 1512-0. 06 0. 0t0+0. l6 0. 0 t0+0. 31 -0. 02 to 0. 04 100 F. Viscosity Increase, percent 9.2 10.1 5. 8 5. 6 TAN Increase 2. 8 2, 65 5. 39 4. 79 1- 36 Sludge, g./100 ml. oil 0.0250 0.0339 0.0887

Blend B and Blend E which correspond to the improved synthetic lubricating oil compositions of the invention possess excellent extreme pressure properties and outstanding anti-corrosive properties with respect to copper and lead metals. Blend A Which is a synthetic fluid containing dimer acid is very poor with respect to its corrosiveness of both copper and lead metals and fails these tests by a wide margin.

Blend D and Blend E were prepared using a different base fluid from Blends A, B and C. Blend E representative of a variation of this invention has excellent E.P. properties and outstanding corrosion inhibiting properties. The anti-corrosiveness toward lead as shown in the Lead Washing Test conducted for a period of 336 hours is particularly outstanding.

It is seen from the table that the additives from Examples 1, 2 and 3 permitted formulation of products resistant to corrosion of metals employed in the construction of jet engines, especially copper and magnesium which are susceptible to oxidative corrosion.

Repeatability and reproducibility of load-carrying determinations in the Ryder Gear Test can be substantially affected by batch to batch and gear to gear variation in metallurgy, hardness and machining. It has been found that a comparative rating system, wherein the test oil is run on one side of a test gear and the reference oil is run on the reverse faces of the gear teeth, greatly improves precision and accuracy of test fluid evaluations.

This comparative rating from this back-to-back test method is expressed in percentage units:

parative rating:

Test Oil Rating, i Reference Oil Ratin x 100% The comparative reference oil may be the standard Ryder Reference Oil B (a grade 1100 mineral oil), product formulation or a synthetic base fluid.

fore, only such'limitations should be imposed as are indicated in the appended claims.

We claim:

1. A synthetic lubricating oil composition comprising a major portion of an aliphatic carboxylic acid ester having lubricating properties and a mon-oamide of an heterocyclic aromatic amine selected from the group consisting of aminopyridines, dipyridylamines and phenothiazines and a material consisting essentially of trimer acids produced by the condensation of unsaturated monocarboxylic acids having between 12 and 22 carbon atoms per molecule in an amount suflicient to impart extreme pressure properties to said lubricating oil composition.

2. A synthetic lubricating oil composition according to claim 1 containing about 0.01 to 1.0 weight percent of said monoamide based on said lubricating oil composition.

3. A synthetic lubricating oil composition according to claim 1 in which said unsaturated monocarboxylic acid has about 18 carbon atoms in the chain.

4. A synthetic lubricating oil composition according to claim 1 containing from about 0.05 to 0.2 weight percent of said monoamide.

5. A synthetic lubricating oil composition according to claim 4 containing the monoamide of 2-amino-pyridine and the trimer of linoleic acid.

6. A synthetic lubricating oil composition according to claim 4 containing the monoamide of phenothiazine and the trimer of linoleic acid.

7. A synthetic lubricating oil composition comprising a major portion of an aliphatic carboxylic acid ester having lubricating properties containing 0.01 to 1.0 weight percent of a monoamide of a heterocyclic aromatic amine selected from the group consisting of aminopyridines, dipyridylamines and phenothiazines and a material consisting essentially of trimer acids produced by the condensation of unsaturated monocarboxylic acids having TABLE II.-COMPARATIVE LOAD CARRYING RATINGS (Back-to-back Ryder gear test method] These data show the effectiveness of the trimer acid monoamide of this invention for improving the load carrying capacities of typical base fluids, whereas a typical antioxidant was without any beneficial effect.

Obviously, other modifications and variations of the invention as hereinbefore set forth may be made without between 12 and 22 carbon atoms per molecule, 0.1 to 2 weight percent of a compound selected from the group consisting of orthothiazine, metathiazine, parathiazine, and phenothiazine, 0.1 to 4.0 weight percent of a compound selected from the class consisting of naphthylamine, phenyl-ot-naphthylamine, diphenylamine, phenyldeparting from the spirit and scope thereof, and thereenediamine, and 0.01 to 0.5 weight percent of a compound selected from the class consisting of quinizarin, ali- Zarin, purpurxanthrene, anthrarufin and chrysazin.

8. A synthetic lubricating oil according to claim 7 containing 0.0001 to 0.1 Weight percent of sebacic acid.

9. A synthetic lubricating oil composition according to claim 7 in which said unsaturated monooarboxylic acid is about 18 carbon atoms.

10. A synthetic lubricating oil composition according to claim 7 containing from about 0.05 to 0.2 weight percent of said monoamide.

11. A synthetic lubricating oil composition according to claim 7 containing the monoarnide of Z-aminopyridine and the trimer of linoleic acid.

12. A synthetic lubricating oil according to claim 7 containing the monoamide of phenothiazine and the trirner of linoleic acid.

13. A synthetic lubricating oil composition comprising a major portion of an aliphatic carboxylic acid ester having lubricating properties containing 0.05 to 0.2. weight percent of a mon'oamide of Z-aminopyridine and the UNITED STATES PATENTS 2,718,503 9/1955 Rocchini 252-515 2,948,598 8/1960 Brehm 25251.5 X 3,247,111 4/1966 Oberright et al. 25251.5 X 3,256,196 6/1966 Eickemeyer et al. 25251.5

OTHER REFERENCES Barnes et al., Synthetic Ester Lubricants, Lubrication Engineering, August 1957, pp. 454-458.

DANIEL E. WYMAN, Primary Examin r.

P. P. GARV'IN, Assistant Examiner.

Claims

1. A SYNTHETIC LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PORTION OF AN ALIPHATIC CARBOXYLIC ACID ESTER HAVING LUBRICATING PROPERTIES AND A MONOAMIDE OF AN HETEROCYCLIC AROMATIC AMINE SELECTED FROM THE GROUP CONSISTING OF AMINOPYRIDINES, DIPYRIDYLAMINES AND PHENOTHIZINES AND A MATERIAL CONSISTING ESSENTIALLY OF TRIMER ACIDS PRODUCED BY THE CONDENSATION OF UNSATURATED MONOCARBOXYLIC ACIDS HAVING BETWEEN 12 TO 22 CARBON ATOMS PER MOLECULE IN AN AMOUNT SUFFICIENT TO IMPART EXTREME PRESSURE PROPERTIES TO SAID LUBRICATING OIL COMPOSITION.