US2809935A

US2809935A - Extreme pressure lubricant

Info

Publication number: US2809935A
Application number: US477134A
Authority: US
Inventors: Paul R Chapman; Allan A Manteuffel; Wolfram George
Original assignee: Pure Oil Co
Current assignee: Pure Oil Co
Priority date: 1954-12-22
Filing date: 1954-12-22
Publication date: 1957-10-15
Anticipated expiration: 1974-10-15

Description

EXTREME PRESSURE LUBRICANT Paul Chapman, Crystal Lake, Allan A. Manteuffel, Union, and George Wolfram, Des Plaines, 111., assignors to The Pure Oil Company, Chicago, Ill., a corporation of Ohio No Drawing. Application December 22, 1954, Serial No. 477,134

ZilCiaims. (Cl. 252- 465) Our invention relates to an improved extreme pressure lubricant. More particularly, our invention relates to an extreme pressure lubricant composition having polymer-inhibiting and corrosion-inhibiting properties.

Extreme pressure lubricants have found extensive use as gear lubricating fluids, such as in the lubrication of gear transmissions of trucks and other vehicles. The lubrication of gears demands lubricants of special qualities, particularly high lubricity and high film strength. When a lubricant is compressed between two moving metallic surfaces, high film strength is necessary to prevent the escape or squeezing out of said lubricant from between said surfaces, with consequent welding. Theextreme pressures to which such lubricants are subjected when compressed between the gear surfaces cause a rise in internal heat which is augmented by any friction generated by lack of point-lubricity. petroleum lubricating oil fractions alone are unsatisfactory in that they do not have requisite high lubricity and high film strength and consequently allow scoring and welding of gears on continued use, together with oil breakdown because of heat generated due to high friction, etc. This is particularly true with more or less highly refined petroleum oil fractions which tend to havev lower lubricity than less highly refined fractions.

Many types of additives have been prepared and added to extreme pressure lubricant formulations for the purpose of augmenting film strength, lubricity and other desired characteristics. Fatty oils and fatty acid esters, for

example, have been added in various amounts and com-v binations to hydrocarbon oil fractions, particularly for the purpose of furnishing oiliness, that is to say, high lubricity. It has also been found that when sulfur-containing compounds are added to extreme pressure lubricants, filmstrength is somewhat increased, and recent formulations have combined ester additives with sulfur by sulfurizing said esters to provide both lubricity and film strength of high. degree. Still morerecently, it has been discovered that the use of phosphorus in combina-.

tion with the sulfur-containing ester additives has further augmented desired film strength to a level of highly satis-' factory performance. Thus, oils and fatty esters may have incorporated therein phosphorus and sulfur by reaction with any one of a number of phosphorus sulfide compounds, such as phosphorus sesquisulfide. The increased performance of phosphorus and sulfur-containing esters as additives for extreme pressure lubricants, when compared with sulfur-containing esters as additives for It has been found that United States Patent I, factory for extreme pressure properties, but also exhibit high lubricity and high film strength, together with mild' inhibition of corrosion stemming from a reduced tendency for the petroleum base oil to break down. Consequently,

sludge, acidic corrosive bodies, and gum-forming com-.

pounds are present in smaller amounts. However, it

has been found that the normally slow rate of polymerization of some fatty esters is accelerated and promotedby the presence of phosphorus in the formulation, particularly where phosphorus appears together With sulfur. When sulfur alone is present in the formulation, that is, where the fatty oil or ester is only sulfurized rather than sulfurized-phosphorized or phosphorylated, promotion and acceleration of the fatty ester polymerization are absent. The polymerization reaction has the deleterious effect on the extreme pressure lubricant formulation of producing insoluble materials which tend to clog themoving parts being lubricated, increase internal and ex-} ternal friction, and thereby contribute to the instabilityof the petroleum base oil with consequently increased pro; duction of acidic bodies and other deterioration com pounds. Furthermore, the increased lubricity and film strength supplied by the extreme pressure additive are dissipated by the conversion of the additive into a polymerized compound. It therefore is extremely advantageous to eliminate or greatly inhibit the polymerization reaction in the extreme pressure lubricant during storage and also during various conditions of use, that is, under increased pressure and/or increased temperature.

It therefore is an object of this invention to provide for inhibition of polymerization in a fatty ester-containing extreme pressure lubricant.

It is another object of this invention to impart anticorrosion properties to an extreme pressure lubricant of the fatty ester-type which contains phosphorus and sulfur compounds.

It is a still further object of this invention to provide a stable extreme pressure lubricant exhibiting inhibition of polymerization of sulfurized-phosphorized fatty esters and showing increased corrosion inhibition.

In general, our invention comprises a composition incorporating a phosphorus-containing fatty ester or a phosphorus-and-sulfur-containing fatty ester, or a mixture thereof, in combination with a polymerization-inhibiting acid-derived aliphatic compound, such as an aliphatic ters containing sulfur and phosphorus are notonly satis- V I amine, an aliphatic amide or an aliphatic amine salt of a fatty acid of carbon chain'length of 16 to 22 carbon atoms.

The base oil in our improved extreme pressure lubricant may comprise any petroleum lubricating oil fraction, such as a neutral or bright stock oil of any suitable viscosity. Non-limiting examples of said petroleum lubricating oil fraction are viscosity bright stock, 170 viscosity bright stock, viscosity bright stock, 200 viscosity neutral oil and viscosity neutral oil. Aromatic extracts from said petroleum lubricating oil fractions are also coutem plated for use as or in the base oil, for example, phenol extract from 150 viscosity bright stock, which means the aromatic extract obtained by extracting with phenol the requisite residual lubricating oil fraction and removing the phenol from the extract phase by flash vaporization, usually under reduced pressure, followed by steam stripping. Aromatic extracts of petroleum lubricating oil fractions derived from extractions with selective solvents other than phenol, such as sulfur dioxide, nitrobenzene,

. 3 chlorex, furfural, dipropionitriles, hydrogen fluoride, dimethyl ammonium diethyl carbamate, etc., are also contemplated. Also within the scope of our invention are mixtures of said extract oils, mixtures of finished lubricating oil fractions, and mixtures of said extract oils with said lubricating oil fractions.

The extreme pressure additive of our composition is derived from any fatty ester of a mono-, di-, or trihydroxy aliphatic alcohol, which ester is soluble in the petroleum base oil utilized in the formulation. The ester preferably is of a fatty acid of 12 carbons atoms or more, and more preferably is one of a fatty acid of 16 carbon atoms or more, for example, palmitic, arachidic, behenic, palmitoleic, petroselinic, vaccenic, linolenic, eleostearic, licanic, parinaric, tariric, gadoleic, arachidonic, cetoleic, erucic, stearic, linoleic, oleic, and other fatty acids both saturated and unsaturated, such as glyceryl trioleate, methyl oleate and dioleate of propylene glycol. Castor oil, lard oil, sperm oil, degras and other fatty oils and fatty grease may also be used. An especially preferable ester is the methyl ester of tall oil fatty acids, a commercial form of which is Metalyn manufactured by the Hercules Powder Company and having the following characteristics:

Percent methyl esters of rosin acids--. 45.0 (typical). Percent methyl esters of fatty acids 47.0 (typical). Percent unsaponifiable modified AOCS Ca 6b-40 8.0 max. Saponification No. (drastic, Hercules method) 155/170. Acid No. (AOCS Da 1442) 5.0 max. Iodine No. (AOCS Cd 1-25) 120/130. Acetyl value (AOCS Cd 4-40) 10.0 max. Color (Gardner 1933) 12.0 max. Specific gravity 20/ 20 C .95/ .975. Flash point C. (COC) 182 min. Freezing point C 10.0 max. Viscosity at 100 F. SUS (ASTM D445-45T) 70/100. Moisture (AOCS ca 2a-5) 0.1 max. Appearance at 20/ 30 C Clear and free of foreign matter.

The alcohol radical of the fatty ester, as mentioned above, may be any mono-, di-, or trihydroxy aliphatic alcohol radical, but it is preferable that the alcohol be a lower molecular weight and lower carbon chain length aliphatic alcohol, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, allyl alcohol, n-butyl alcohol, isoamyl alcohol, sec.-butyl alcohol, tert.-butyl alcohol, isobutyl alcohol, isopropyl alcohol, n-amyl alcohol, tert.-arn'yl alcohol, glycol, glycerol, propylene glycol, trimethylene glycol and the like, whether it contains one, two or three hydroxyl radicals. The fatty ester may be used alone or in combination with other fatty esters. If a mixture is used, one or more of the esters may be sulfurized and the other esters may be phosphorized or phosphori'zedsulfurized, or alternatively, all the esters may be phosphorized-sulfurized or phosphorylated. An example of a mixture is Metalyn in that it comprises a mixture of methyl esters of the fatty acids of tall oil which contains a mixture of linoleic acid, oleic acid and the resin acids, principally abietic acid. The proportions of the constituents fluctuate to some extent from sample to sample.

The fatty esters may be sulfurized by any one of a number of known methods, including the following: Elemental sulfur in the form of finely powdered sulfur may be sifted in small increments into a kettle containing the fatty ester or fatty ester mixture, for example, Metalyn. The constituents in the kettle are heated to about 270 F. to 285 F. while being vigorously agitated by a mechanical agitator. 1n the case of Metalyn it is preferable to react 93 parts of Metalyn with 7 parts by weight of sulfur. The ratio of Metalyn to sulfur may suitably vary from about 85 parts Metalyn with parts sulfur to about 97 parts Metalyn with 3 parts sulfur. Suitable ratios are known for other fatty ester mixtures. After the addition of the sulfur to the fatty ester, the temperature of the mixture is raised to about 350 F. and the reaction is allowed to proceed for about 7-8 hours until fully completed, as indicated by a suitable test, such as a copper strip test. Shorter reaction periods may be employed where more highly active catalysts are available and fatty esters and sulfur react more quickly. During the final stages of reaction, the temperature may be allowed to rise to about 375 F. to insure complete reaction. The aforesaid copper strip test consists of immersing a copper strip in a sample of the product for one minute at 300 F., and if the copper strip remains peacock, the reaction is completed. In the case of Metalyn, the final product may contain about 6.25 percent of sulfur as the preferred quantity, although sulfurized Metalyn or other fatty esters may contain various amounts, such as 3-10 percent of sulfur. Where smaller amounts of sulfur are desired, the reaction time and/or temperature may be reduced. Conversely, if larger amounts of sulfur are to be incorporated, longer reaction times and/ or higher temperatures will be required to obtain the finished product. However, temperatures in excess of 400 F. should be avoided.

The introduction of phosphorus into the fatty ester may be brought about by reaction of the fatty ester or fatty ester mixture with any suitable phosphorus sulfide, such as, phosphorus pentasulfide (P285), or preferably phosphorus sesquisulfide (P483), the latter containing trivalent phosphorus and forming a complex phosphorusand-sulfur-bearing end-product in which substantially all of the phosphorus of the phosphorus sulfide is present. In the case of phosphorus sesquisulfide, the fatty ester is, for example, mixed in a kettle with the phosphorus sesquisulfide and the mixture is heated to 195 F. with continuous agitation. Then the temperature is increased to 220-230 F. and maintained there for about 4 to 5 hours or until the reaction with the phosphorus sesquisulfide is completed. Substantially all of the phosphorus and all of the sulfur from the phosphorus sesquisulfide are incorporated in the fatty ester or in the fatty ester mixture during the reaction period. Under controlled conditions the quantity of phosphorus introduced in the ester may be varied, as may the quantity of sulfur introduced into the ester. Thus, an ester may be treated so as only to phosphorize it, the amount of sulfur being introduced being negligible.

An example of one procedure is the reaction of glyceryl trioleate in amount of parts by weight with 5 parts by weight of finely divided phosphorus sesquisulfide at 185 R, which temperature is then raised to 225 F. and maintained there for 4.5 hours under continuous agitation with a mechanical stirrer in a conventional reaction kettle. The end-point is determined by immersion of a copper strip in a sample of the reaction mixture at 210 F. for three minutes. On removal, the strip should show a bright surface. Upon completion of the reaction, the glyceryl trioleate contains both phosphorus and sulfur, the compound being a complex, as yet not clearly defined, structure. The percentage by weight, for example may be 1.26 for the phosphorus and 0.97 for the sulfur, but varies in each case depending upon the reaction conditions.

As mentioned above, combinations of more than one ester, in which one or more of the esters may contain phosphorus with or without sulfur and the remaining esters may contain sulfur with or without phosphorus, are contemplated. Thus, for example, an effective combination is sulfurized Metalyn together with sulfurizedphosphorized glyceryl trioleate. This combination is preferred in our composition because of its low cost and the fact that it is in general compatible with various petroleum lubricating oil fractions. In the case 'of the Metalyn-glyceryl trioleate combination, it has been found r that it is generally undesirable .to. treat the Metalyn or similar esters with phosphorus sulfide in that the phosphorization reaction immediately produces some poly merization and decreased production of end-product. .This situation extendsto the methyl esters of tall oil as well as the ethyl, propyl, butyl and amyl esters of tall oil, and particularly to the isopropyl esters, isobutyl esters and similar branch-chain esters of tall oil. The incorporation of the phosphorus in the fatty ester is therefore preferably performed with fatty esters other than those of the tall oil type; it has been shown that mono-, di-, and trioleates of glycerol exhibit no immediate polymerization upon reaction with the phosphorus sulfide and are therefore preferred fatty esters for reaction with the phosphorus sulfide. The extreme pressure additive produced as outlined above increases the temperature stability, pressure resistivity, lubricity, and film strength, and fortifies to some extent the base oil against deterioration and formation of corrosive bodies. It may be present in any effective minor amount, such as, for example, percent by weight of the final composition. The polymerization-inhibiting and corrosion-inhibitin agent of our formulation may be present in any effective minor amount, such as 0.05-10 percent by weight of the final composition, and comprises at least one member of the class of compounds characterized as basic organic ntirogen compounds derived from at least one fatty acid containing a carbon chain length of at least 16 carbon atoms. These compounds fall into three sub-classes, the fatty amides, the fatty amines and the aliphatic amine salts or soaps of fatty acids having carbon chain lengths of at least 16 carbon atoms and not more than 22 carbon atoms. The additive must be oil-soluble or be used in conjunction with a suitable assisting agent which renders said additive oil-soluble. Mixtures of the compounds of the three sub-classes are therefor contemplated as the polymerization-inhibiting and corrosion-inhibiting additive.

The fatty amines referred to and effective as the polymerization-inhibiting and corrosion-inhibiting agents in our formulations may be only amines having at least one carbon chain of 16-22 carbon atoms. The term fatty amines indicates, according to current terminology, the fact that the amines were derived from fatty acids of comparable carbon chain length. Such fatty amines are saturated primary amines such as, palmitylamine, stearylamine, arachidylamine, behenylamine and the like; primary mono-unsaturated amines, such as oleylamine, palmitoleylamine, petroselinylamine, vaccenylamine, gadoleylamine, cetoleylamine and erucylamine; diunsaturated amines, such as linoleylamine; tri-unsaturated amines, such as linolenylamine, licanylamine and eleostearylamine; and secondary amines such as Armeen 2C and Armeen 2HT, commercial mixtures of secondary fatty.

amines as shown below:

Armeen T v Percent Armeen N-alkyl radical 20, Percent hexadecy octadecy1 amines and other types of the amines of the specified 6 carbon chain lengths may be utilized. Oil-soluble tertiary amines having at least one carbon chain of 16-22 carbon atoms are also contemplated.

Many methods may be invoked for the preparation of the desired amines. However, one suitable method involves the reaction of a fatty acid or a fatty acid mixture with ammonia for the production of an ammonium salt of a fatty acid which when heated decomposes to a fatty amide Which in turn forms an aliphatic nitrile. Upon hydrogenation the nitrile is converted into the desired fatty amine. Other methods available for the production of amines are, for example, alkylation of ammonia with chlorides of suitable carbon chain length, treatment of amides with sodium hypochlorite or sodium hypobromite, and processes such as the Hofmann reaction, the Curtius reaction and the Gabriel synthesis.

Armeen-S is a commercial product manufactured by Armour & Company, Chicago, Illinois, which comprises a mixture of fatty amines, namely 10 parts by weight of hexadecylamine, 10 parts of octadecylamine, 35 parts of octadecenylamine and 45 parts of octadecyldienylamine, that is, a palmitylamine, stearylamine, oleylamine and linoleylamine. This amine mixture is suitable for use as the polymerization-inhibiting and corrosion-inhibiting agent.

Armeen-HTD is also manufactured by Armour & Company, Chicago, Illinois, and comprises a mixture of about 25 parts by weight of hexadecylamine, 70 parts by weight of octadecylamine, and 5 parts by weight of octadecenylamine. In both of the above products the proportions of amine components may vary with different samples.

Duomeen T is a third commercial preparation of Armour & Company, Chicago, Illinois, which is also suitable for use in the composition of our invention. Duomeen T is a member of the group of fatty diamines which are more particularly described as N-alkyl trimethylene diamines and have the following general formula:

In the case of Duomeen T, the alkyl group is derived from tallow acids and is composed of a mixture of C16 to Cu; normal saturated hydrocarbon chains and a C18 mono unsaturated chain.

The amides of our invention which may be utilized as polymerization-inhibiting and corrosion-inhibiting agents in our composition are of comparable carbon chain length and configuration to the above-mentioned amines and are, for example, the following: stearylamide, oleylamide, palmitylamide, linoleylamide, arachidylamide, behenylamide, palmiteolylamide, petroselinylamide, vaccenylamide, gadoleylamide, cetoleylamide, erucylamide, linolenylamide, licanylamide, eleostearylamide, tarirylamide, parinarylamide and the like. The amides which are suitable may be with at least one saturated or unsaturated carbon chain ranging from C16 to C22. The unsaturated amides may have one or more double or triple bonds. They may also have more than one amide radical per molecule. The methods of preparation are similar to those described above for the amines; for example, reactions of ammonia with fatty acids, followed by pyrolysis, and reactions involving esters, or organic acid chloride or anhydrides, as noted above. They may also be prepared by partial hydrolysis of nitriles. Each is oil-soluble or soluble in an oil-soluble assisting agent.

Duomeen T Dioleate is an Armour & Company, Chicago, Illinois, commercial product which is suitable for use as the corrosion and polymer formation inhibitor and which may be characterized as a substituted diaminesalt of a fatty acid. Duomeen T Dioleate is water-insoluble and is thoroughly soluble in isopropyl alcohol, benzene, tetrachloroethylene, mineral oil, naptha, ethyl acetate, lard oil and similar substances. It is obtained by 8 in. swing diameter for minutes, then the supernatant oil was decanted and the tubes allowed to drain for 1 hour at room temperature. Solid residue was washed H with ASTM naphtha to an oil-free state and dried at 220 A1-ky1 1 f 'QE-[Z CH2 CH2 1?H ell-B33000 5 F., and the tube weighed to the nearest mg.; where the 2 residue was liquid, it was restored for 60 days, then re- Duomeen T Dioleate upon high heating breaks down to centrifuged and the Volume of sehafated hqulds f the comparabla amide and Water served to the nearest 0.05 ml. Where the separated ma- Duomeen T Dioleate is typical of the aliphatic amine tellal 50nd, averhg e.lncretlsfi Welght of each tube salts of fatty acids of Carbon chain lengths f 42 and residue over the initial weight of the clean tube was carbon atoms wherein the amine radical has 1622 carreported In R p f by Weight of the -P bon atoms. Other examples are Duomeen T distearate, leum materltll Y the p Where the P?" DuomeenT dipalmitate, stearylamine oleate and the like. rated mateflal was q the Volume Was 'tP 111 Said salts have varying degrees of stability. Each salt f P perctjnt by Volume of the non-Petroleum matemust either be oil-soluble or soluble in an assisting agent nal iongmany the P which in turn is soluble in oil. The amine radical of the h best results fq a heat stablllty standpomt e salt may have an alkyl substituent of a total number of Ohtamed by comhlnlllg AImeeh-S and Duomeen T carbon atoms which when added to the number of carbon Dloletfte as shown blends and M of m The atoms of the amine nucleus totals 1622 carbon atoms. Sum-126d Metalyrl'Phosphonzed glyceltyl moleat? Thus, for example, with amine radicals having 3 nuclear 20 frame pressure additive of the gear lubncant used 1n the carbon atoms, an alkyl substituem of 13 to 19 carbon tests reported in the tables contains three parts by weight atoms would be present, as in Duomeen T Dioleate. 0f sulfhl'lzed l and P p P P F Z Q g y- Acryloid 15.0" is a commercial methacrylate ester yl 9 the 1 'P of both of which 13 6- copolymer sold under this name by Rohm & Haas and has H scribed 1n the speclficatlonthe f ula A further test showed that ArmeeihS and Duomeen CH3 I Dioleate prevented the formation of polymers during l the CRC-L22 Storage Stability test when used in con 2 centrations of about 0.1 percent or more, but concentra- (FOrOR. tions of about .01 percent of the aforesaid additives failed in which R is predominantly a mixture of cetyl, lauryl to prevent polymerization during the test period. and octyl groups and the molecular weight of the polymer A gear oil containing of Armeen-S was subjected to a is about 10,000 to 15,000. series of bench tests, namely, the ASTM turbine oil rust TABLE I Storage stability characteristics of extreme pressure lubricants Extreme Pressure Blend A B C D E F G H I J K L M SAE Grade 'Extreme Pressure Lube 99.8 99.9 99.8 99.9 99.8 99. 9 99.9 99. 85 99. 85 99. 85 99. 85 99.9 RD 1937 2 0. 2 Duomeen T leate Armeen S Duomeen T Storage Stability CBC L22 (200 F.) 48 .05 00 00 4 Fail 00 00 00 .05 00 Time in Days 6 .13 30 30 3 30 30 30 30 30 30 30 Rating H. D. H. D. L. 'P V. L. I V. L. P Film Film Trace Trace V. L. P. Trace CR O 11-22 (300 F.

Time in Days. 1 3 8 3 2 6 6 6 6 Rating, H. D. H. D. H. D H. D. H. D. L. P L. P L. P. H. D

1 Formulation, percent by wt. composition:

10 (3 sulfurizcd Metalyn) (1 phosphorized GT0). 1 dibenzyl disulflde. 56-150 viscosity bright stock. 32-170 viscosity neutral. 1-Acryloid 150.

. RD 1937 is a. soya amine oleate st tB netq s q l e stahi t te Clear. Trace. Film. Very light peppery deposit-V. L. P. Light peppery dBDOSitfL- P. Heavy deposit-H. D.

4 Two .phase liquid separation.

The various combinations of Armeen-S, Duomeen 'T and/or Duomeen T Dioleate as polymerization-inhibiting, gear-oil additives were satisfactory for the duration of the CRC-;L'22 storage stability test, which test was performed in the following manner: Two centrifuge ubes 100 ml. cone-shaped A STM designation D96) were rinsed with naphtha, cleaned with concentrated sulfuric acid saturated with sodium or potassium dichromate, rinsed with distilled water, rinsed with 95% alcohol or S- free acetone and air-dried; they were then Weighed t0 the nea e t m and 0. Q the t s u i a placed in each tube. The tubes were then placed in storage at the desired temperature in a darkened room for 30 days. Q1; 'c onclusion,of the storage period, the tubes were centrifuged at 115.00 R. P. M. in' acentrlfrigeof 15-17 abilizer similar to Duomeen T Dloleate.

test, the Modified SAE machine test and the Timken test.

The turbine oil rust test was performed according to the procedure of test method ASTM designation D665- 53T and may be briefly described as follows:

A mixture of 300 ml. of the oil under test is stirred with 30 ml. of distilled or synthetic sea water, as required, at a temperature of F. with a cylindrical steel specimen completely immersed therein, usually for a period of 24 hours. The specimen is then withdrawn and examined under normal light without magnification to determine the degree 'of rusting. A rusted specimen is one on which any rust spot or streak is visible by visual inspection.

"Th i e AE m eh e e is p fo med n t e following manner:

50 Break-in duration hrs 0.5 Test beam load lbs 110 Test duration hrs 15.8 Upper shaft speed R. P. M. 264 Shaft ratio 10.4/1 Temperature (oil pot) F 225 The SAE machine used is the SAE extreme pressure lubricant testing machine (CRC designation EL-l7-545) and consists essentially of a device in which 2 cylindrical test specimens are rotated in line contact with each other and in opposite directions, with provision for controlling the speed of rotation, the slipping velocity, and the rate of applying pressure at the line contact between the rotating cylinders. v

The Timken CRC designation L18-545 test is used, a brief summary of which follows: The Timken extreme pressure lubricant testing machine (CRC desig nation EL-18-545) is cleaned and then about 1 pint of the test lubricant is put into it, circulated through it for 2-3 minutes and discarded. Fresh test lubricant at 125 i5" F. is placed in the machine and circulated therein for 15 minutes prior to the test. The test cup (average surface finish 20-30 microinches) is placed on the mandrel, and the test block in the holder on the machine. Test cup and block are then covered with test lubricant. When the apparatus is properly aligned and the reservoir on the machine is about 50% full of lubricant, the machine is started. The mandrel revolves at 800 R. P. M., producing rubbing speed on the test cup of 400 F. P. M. The desired load is applied to the lever arm of the machine which runs 10 minutes unless scoring occurs earlier. The test is repeated with a new surface of the test block, a new cup and a heavier load if no scoring occurs. Tests are run until the-weight necessary to cause scoring is found. The Width of the score on the test block is measured and the load in p. s. i. at the end of the test can be calculated as follows: 7

beam load (1b.) X 10 score width (in) Xscore length (in) the load-carrying capacity of the test lubricant is repeated in p. s. i. at maximum load in lbs. that can be applied without causing a score.

The results of the above tests in which Armeen-S wax incorporated with sulfurized Metalyn and phosphorized glyceryl trioleate in mineral oil as a gear oil formulation appear in Table II below:

p. s. i.

TABLE II E. P. Lube I'IB125 52194 80/90 SAE Oil Composition by weight:

E. P. Base 10 10 i3 (Suliurized Metalyn) (3) (3g (5) (Phosphorized GT0).... (1) (1 (1) Dibenzyl disulfide 1 1 1 Acryloid 150 1 1 1 1 150 Viscosity Bright Stock 56 56 54 170 Viscosity Neutral Lubric 31. 9 32 31 Armeen S 0. l Viscosity, 210 F".-. 83. 7 83 81.7 Viscosity, 100 F 790. 9 779 759 Viscosity Index. 107 108 108 ASTM Turbine Oil Rust Test.. Passed Failed Failed Timken Test:

Beam Load, lbs 50 59 Pressure, p. s. i 32, 000 40, 000 38, 000 Modified SAE Test, Weight Loss, mg 18. 8 2 32. 4

1 Acryloid 150 is a viscosity index improver which also functions as a pour point depressant and is a methaerylate polymer.

' Armeen S appears to have no adverse efi'ect on the performance of the extreme pressure lubricant; and it in hibits rust, as shown by the ASTM turbine oil rust test, as Well as preventing polymer formation.

Armeen I-ITD was similarly evaluated by a series of bench tests to determine its qualities as a stabilizer for gear oil formulations.

The function of dibenzyl disulfide formulations in formulations appearing in tables in this specification is to provide additional, properly available sulfur to the gear oil to assure satisfactory performance of the gear oil at low temperatures and pressures. The Armeen HTD polymerization-inhibiting additive appears to have no adverse efiect on the gear oil formulation; that is, the Arrneen HTD imparts its polymerization-inhibiting characteristics without depreciating the extreme pressure characteristics of the formulation.

Duomeen T. Dioleate was similarly subjected to a series of bench tests to evaluate its stability in gear oil containing sulfurized Metalyn and phosphorized glyceiyl trioleate. The results appear below in Table III.

TABLE III E. P. Lube ITB126 52-194 /90 SAE Oil 10 10 13 (1) 1 1 l Acryloid A 1 1 1 150 Viscosity Bright Stock 56 56 54 Viscosity Neutral Lubricating Oil 31.9 32 81 Duomeen T Dioleate 0.1 Viscosity 210 F. SUS 83.7 83 81. 7 Viscosity 100 F. SUS 170.9 779 759 Viscosity Index 107 108 108 AS'IM Turbine Oil Rust Test Passed Faded Failed Tirnken Test:

Beam Load, lbs 65 59 51 Pressure, p. s. i 39,000 40, 000 38, 000 Modified SAE Test-.. Passed Passed Failed Weight Loss in mg 22. 2 25 32. 4

Duomeen T Dioleate had no adverse effect on the extreme pressure characteristics of the gear oil formulation, as evaluated by the modified SAE test, the Tirnken test, and the ASTM turbine oil rust test. It was found that 0.l percent by weight of Duomeen T Dioleate is sufficient to prevent traces of sediment accumulating during the CRCL22 storage stability test and inhibits corrosion by the composition. Comparable results were obtained when sulfurized methyl esters of animal fatty esters were substituted for Metalyn in the Metalyn-phosphorized glyceryl trioleate extreme pressure additive; that is, when sulfurized methyl esters of animal fatty acids were used in combination with phosphorized glyceryl trioleate and Duomeen T. Dioleate, the latter in about 0.1 percent concentration, polymerization of the extreme pressure additive in the gear oil was inhibited. Marked inhibition of corrosion by the gear oil was also noted.

A further example of the polymerization-inhibiting properties of the composition of our invention appears below:

A concentrate of 30.5 percent of Duomeen T Dioleate was prepared in SAE 80/90 grade gear oil containing sul furized Metalyn and phosphorized glyceryl trioleate and this blend was added to 6,000 gallons gear oil base stock. The addition of the Duomeen T Dioleate concentrate was made in increments of 10 and 15 gallons while mixing was carried on by recirculating the gear oil from the bottom of the storage tank to the top with the pump. It was found that Duomeen T Dioleate prevented the further polymerization of the gear oil for the test period of 90 days, although polymers which had formed before the addition of the Duomeen T Dioleate could not be reabsorbed by the addition of said Duomeen T Dioleate, and appeared on the surface of the gear oil during the storage period.

The results with the polymerization-inhibiting and corrosion-inhibiting additives of our composition are contrasted with those obtained when comparable amounts, about 0.1 percent by weight of lower molecular weight, amines were added to sulfurized Metalyn and phosphorized glyceryl trioleate in hydrocarbon oil. When tertiaryoctylamines and tertiary-butylamines were each tested by the CRC-L-22 storage stability test, having been incorporated in the above-mentioned gear oil in 0.1 percent by weight concentration, the resulting gear oil exhibited continued substantial polymer deposition and at the end of the 30 day test period the samples of the lubricant showed separation of liquid into two or more phases. In addition, the beneficial corrosion-inhibiting characteristics noted upon the addition of the polymerization-inhibiting additive of our composition were absent when the gear oil formulations containing amines with fewer than 16 carbon atoms were tested by means of the NRL static water drop test as set forth in MlL-Pl7272 (ships) 18 July 1952. A summary of the test is as follows: The test specimen 2 inch cold-rolled steel (SAE 1020) in the form of an equilateral triangle) is polished on its dimpled side with sandpaper and placed into pure benzene, swabbed with clean gauze, placed into more pure benzene and boiled 34 minutes, put into petroleum ether and boiled 1- minute. The test specimen is immersed with the concave side of its dimple uppermost in a. beaker containing oil so that the latter covers it to about 0.25 inch depth. The beaker containing the oil and sample is heated to 140: 2 F. for 1 hour and removed. A drop of water. 0.2 ml., is placed in the oil so as to rest in the dimple of the specimen, then the beaker is stored at 140: 2 F. and observed daily for failure of the specimen, i. e., the first sign of rust which increases in intensity the following day. Four test specimens are run. Where the water drop slowly disappears, it is restored by addition thereto to original size when it reaches 50% of its original diameter. Three of the four specimens should be free of rust for the test period in order to pass test.

In summation, it has been found that, contrary to expectations, when about 0.1 percent by weight of the basic nitrogen-containing polymerization-inhibiting and corrosion-inhibiting additives of our composition are added to a lubricant incorporating a fatty ester or a mixture of fatty esters which have been phosphorized and/ or phosphorized-sulfurized, the promotion of polymerization of said fatty ester, or esters thought to be brought about by the presence of phosphorus, particularly phosphorus in the presence of sulfur, is counteracted so that satisfactory stability of the lubricant is achieved. Furthermore, extreme pressure lubricants containing the above-mentioned constituents incorporated in a mineral oil fraction exhibit corrosion inhibition. The polymerization-inhibiting and the corrosion-inhibiting characteristics of the formulaton are present both during storage of the lubricant and during use of the lubricant under conditions of extreme pressure and elevated temperatures.

The constituents of our composition may be added together in any suitable manner, that is, with or without stirring, in conventional apparatus, and any sequence; the constituents may be added intermittently, continuously, swiftly or slowly, in any order to achieve a homogeneous extreme pressure lubricant.

In addition, the composition of our invention which comprises a petroleum base oil, together with the extreme pressure and the polymerization-inhibiting and corrosioninhibiting additive indicated, may include other conventional lubricating oil additives added to the composition for known specific properties, and which do not substantially interfere with extreme pressure characteristics, polymerizadon-inhibition, or corrosion-inhibition. Such additional additives may be viscosity index improvers, such as, Parat-one a polyisobutylene polymer, Acryloid polymers of the esters of methacrylic acid and higher fatty alcohol, and Santodex, an alkyl styrene polymer;

Paraflow a. complex condensation product of parattin wax and naphthalene, Santopour, a parafiin wax, phenolic condensation product, and Acryloid described above; and other assisting agents, for example, foam depressants such as Dow Corning Fluid DC200, a silicone polymer, and Monsanto Chemical Companys PC-l308, and the like.

Whenever the terms ArmeenS, ArmeenHTD, Duomeenand. Duomeen-T Dioleate are used in the claims they shall mean. the substance as defined in the foregoing specification.

We claim:

1. An extreme pressure lubricant which comprises a mineral oil, an. amount sufficient to impart extreme pressure properties to. the. oil of extreme pressure additive comprising a phosphorized and sulfurized ester of a fatty acid and aliphatic alcohol, and a nitrogen-containing compound comprising at least one member of the group consisting of aliphaticv amines having at least one carbon chain of at least 16 carbon atoms, aliphatic amides having at least one carbon chain of at least 16 carbon atoms and aliphatic amine salts of fatty acids of carbon chain of at least 16 carbon atoms, wherein the amine radical has at least 16 carbon atoms, in a polymerization-inhibiting amount.

2. An extreme pressure lubricant which comprises a major amount of a petroleum lubricating oil, an amount sufficient to impart extreme pressure properties to said oil of. a phosphorized and sulfurized ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic. alcohol, and' a nitrogen-containing compound comprising at least one member of the group consisting of fatty amines having at least one carbon chain of at least 16 carbon atoms and not more than 22 carbon atoms, fatty amides having at least, one carbon chain of at least 16 carbon atoms and not more than 22 carbon atoms, and aliphatic amine salts of fatty acids of carbon chain length of at. least 16 carbon atoms and not more than 22: carbon atoms, wherein the amine radical has at least 1-6 carbon atoms andv not more than 22 carbon atoms, in apolymerization-inhibiting amount.

3. An extreme pressure lubricant which comprises a major amount of. a petroleum lubricating oil, an amount sufficient to impart extreme pressure properties to the said lubricating oil of amixture of esters, which have been phosphorized and sulfurized with phosphorus sesequisulfide, of fatty acidsv of carbon chain lengths of at least 12 carbon atoms and lower aliphatic alcohols, and a nitrogen-containing compound comprising at least one member of the group consisting of fatty amines of carbon chain lengths of at least 16 carbon atoms and' not more than 22 carbon atoms, fatty amides of carbon chain length of at least 16 carbon atoms and not more than 22 carbon atoms,v and aliphatic. amine salts of fatty acids of carbon chain lengthof at least 16 carbon atoms and not more than 22 carbon atoms wherein the amine radical has at least 16 carbon atoms and not more than 18 carbon atoms, in a polymerization-inhibiting amount.

4. An extreme pressure lubricant which comprises a major amount of a petroleum lubricating oil, a sulfurized ester, of tall oil and a lower aliphatic alcohol, in combination with an ester of a fatty acid of carbon chain length of atleast 16 carbon atoms and a trihydroxy alcohol, which ester has been chemically reacted with phosphorus sesquisulfide, the latter two components in an amount sufficient to impart extreme pressure properties to theoil, and at least about 0.1 percent by Weight of the total composition, sufficient to inhibit polymerization, of a nitrogen-containing compound comprising at least one member of the group consisting of fatty amines having at least one carbon chain of at least 16 carbon atoms and not more. than 22 carbon atoms, fatty amides havingat least one carbon chain of at least 16 carbon atoms and not more than 22 carbon atoms, and aliphatic amine salts of fatty acids of at least 16 carbon atoms and not more than 22 carbon atoms wherein the amine radical has an alkyl .substituent which has at least 18 carbon atoms and not more than 19 carbon atoms.

5. An extreme pressure lubricant which comprises a mineral oil in major amount, an amount sufficient to impart extreme pressure qualities to said mineral oil of at least one phosphorus-containing ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic alcohol, obtained by reacting said ester with a phosphorus sulfide and an aliphatic amine having at least one carbon chain of at least 16 carbon atoms and not more than 22 carbon atoms in an amount sufficient to inhibit sediment formation in the composition.

6. The lubricant of claim in which said amine has at least one hydrogen atom attached to at least one nitrogen atom.

7. An extreme pressure lubricant which comprises a mineral oil in a major amount, an amount sufficient to impart extreme pressure qualities to said mineral oil of at least one phosphorus-containing ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic alcohol, obtained 'by reacting said ester with a phosphorus sulfide and an aliphatic amide having at least one carbon chain of at least 16 carbon atoms and not more than 22 carbon atoms in an amount sufficient to inhibit sediment formation in the composition.

8. An extreme pressure lubricant which comprises a petroleum lubricating oil in a major amount, an amount sufiicient to impart extreme pressure qualities to said petroleum lubricating oil of at least one phosphorus-contaiuing ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic alcohol, obtained by reacting said ester with a phosphorus sulfide and an aliphatic amine salt of a fatty acid of carbon chain length of at least 16 carbon atoms and not more than 22 carbon atoms, wherein said amine radical has at least 16 carbon atoms and not more than 22 carbon atoms, in an amount suflicient to inhibit sediment formation in the composition.

9. The lubricant of claim 8 in which said aliphatic amine salt is an alkyl substituted trimethylene diamine salt.

10. An extreme pressure lubricant which comprises a petroleum lubricating oil in major amount, an amount sufiicient to impart extreme pressure qualities to said petroleum lubricating oil of at least one sulfurized and phosphorized ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic alcohol, and an aliphatic amine having at least one carbon chain of at least 16 carbon atom and not more than 22 carbon atoms in an amount sufiicient to inhibit sediment formation in the composition.

11. The lubricant of claim 10 in which said amine has at least one hydrogen atom attached to at least one nitrogen atom.

12. An extreme pressure lubricant which comprises a petroleum lubricating oil in a major amount, an amount sufficient to impart extreme pressure qualities to said hydrocarbon petroleum lubricating oil of at least one sulfurized and phosphorized ester of a fatty acid of carbon chain length of at least 12 carbon atoms and a lower aliphatic alcohol, and an aliphatic amide having at least one carbon chain of at least 16 carbon atoms and i of at least 12 carbon atoms and a lower aliphatic alcohol,

and an aliphatic amine salt of a fatty acid of carbon chain length of at least 16 carbon atoms and not more than 22 carbon atoms, wherein said amine radical has at least 16 carbon atoms and not more than 22 carbon 14 atoms, in an amount suflicient to inhibit sediment formation in the composition.

14. The lubricant of claim 13 in which the amine salt is an alkyl substituted trimethylene diamine salt.

15. An extreme pressure lubricant which comprises a major amount of petroleum lubricating oil, a minor extremepressure-imparting amount of an extreme pressure additive which comprises sulfurized methyl esters of tall oil and glycerol trioleate phosphorized-sulfurized with phosphorus sesquisulfide, in a ratio of one to ten parts tall oil esters to one part glycerol trioleate, and a minor amount of a mixture of fatty amines containing 10 parts of hexadecylamine, 10 parts of octadecylamine, 35 parts of octadecenylamine and 45 parts of octadecyldienylamine, sufficient to inhibit polymer formation.

16. An extreme pressure lubricant which comprises about 56 percent by weight of viscosity bright stock oil, about 31.9 percent by weight of viscosity neutral oil, about 10 percent by weight of an extreme pressure additive which comprises sulfurized methyl esters of tall oil and glycerol trioleate phosphorized-sulfurized with phosphorus sesquisulfide, in a ratio of one to ten parts tall oil esters to one part glycerol trioleate, about 1 percent by weight of dibenzyl disulfide, about 1 percent byweight, as a viscosity index improver, of the polymer of mixed cetyl, octyl and lauryl esters of methacrylic acid having l0,00020,000 molecular weight and about 0.1 percent by weight of a mixture of fatty amines containing 10 parts of hexadecylamine, 10 parts of octadecylamine, 35 parts of octadecenylamine and 45 parts of octadecyldienylamine.

17. An extreme pressure lubricant which comprises a major amount of a petroleum lubricating oil, a minor extreme pressure-imparting amount of an extreme pressure additive which comprises sulfurized methyl esters of tall oil and glycerol trioleate phosphorized-sulfurized with phosphorus sesquisulfide, in a ratio of one to ten parts tall oil esters to one part glycerol trioleate, and a minor amount of a compound having the formula sufiicient to inhibit polymer formation.

18. An extreme pressure lubricant which comprises about 56 percent by weight of 150 viscosity bright stock oil, about 31.9 percent by weight of 170 viscosity neutral oil, about 0.1 percent by weight of a compound having the formula about 1 percent by weight of di'benzyl disulfide, about 1 percent by weight, as a viscosity index improver, of the polymer of mixed cetyl, octyl and lauryl esters of methacrylic acid having 10,00020,000 molecular weight, and about 10 percent by weight of an extreme pressure additive which comprises 3 parts of sulfurized methyl esters of tall oil and one part of glycerol trioleate which has been phosphorized-sulfurized with phosphorus sesquisulfide.

19. An extreme pressure lubricant which comprises a major amount of a petroleum lubricating oil, a minor extreme pressure-imparting amount of an extreme pressure additive which comprises sulfurized methyl esters of tall oil and glycerol trioleate phosphorized-sulfurized with phosphorus sesquisulfide, in a ratio of one to ten parts tall oil esters to one part glycerol trioleate, and a minor amount of stearylamide sufiicient to inhibit polymer formation.

20. An extreme pressure lubricant which comprises about 56 percent by weight of 150 viscosity bright stock oil, about 31.9 percent by weight of 170 viscosity neutral '15 w oil, about 0.1 percent by weight of stearyi amide, about References Cited in the file of this patent 1 percent by weight of dibenzyl disulfide, about I percent UNITED STATES PATENTS by weight, as a viscosity index improver, of the polymer of mixed cetyl,. octyl and lauryl esters of methacrylic acid having 10,00020,000 molecular weight, and about 5 10 percent by Weight of an extreme pressure additive comprising 3 parts of .sulfurized methyl esters of tall oil and one part of glycerol trioleate which has been phosphorized-sulfurized by phosphorus sesquisulfide.

2,151,300 Moran Mar. 21, 1939 2,268,608 McNuIty Jan. 6, 1947-

Claims

1. AN EXTREME PRESSURE LUBRICANT WHICH COMPRISES A MINERAL OIL, AN AMOUNT SUFFICIENT TO IMPART EXTREME PRESSURE PROPERTIES TO THE OIL OF EXTREME PRESSURE ADDITIVE COMPRISING A PHOSPHORIZED AND SULFURIZED ESTER OF A FATTY ACID AND ALIPHATIC ALCOHOL, AND A NITROGEN-CONTAINING COMPOUND COMPRISING AT LEAST ONE MEMBER, OF THE GROUP CONSISTING OF ALIPHATIC AMINES HAVING AT LEAST ONE CARBON CHAIN OF AT LEAST 16 CARBON ATOMS, ALIPHATIC AMIDES HAVING AT LEAST ONE CARBON CHAIN OF AT LEAST 16 CARBON ATOMS AND ALIPHATIC AMINE SALTS OF FATTY ACIDS OF CARBON CHAIN OF AT LEAST 16 CARBON ATOMS, WHEREIN THE AMINE RADICAL HAS AT LEAST 16 CARBON ATOMS, IN A POLYMERIZATION-INHIBITING AMOUNT.