US2944020A - Anti-wear lubricating oil composition - Google Patents

Description

United States Patent ANTI-WEAR LUBRICATING OIL COMPOSITION Guy M. Verley, Harvey, assignor to SinclainRe'fin! ing Company, New York, N.Y., a corporation of Maine V v V No Drawing. Filed May 11, 1956, so. No. 584,181

2 Claims. (c1.2s2-32.7

This invention relates to mineral oil compositions and more particularlyto improved lubricating oils containing a zinc dithiophosphate together with nickel phenol sulfide and preferably having other additives such as detergents and anti-wear agents. I

With the advent of higher compression internal combustion engines and increases in horsepower, muchdrfli culty has been experienced in formulating a suitable lubricating oil composition capable of operating under severe conditions to protect effectively metal surfaces which come in contact with the oil. In an effort to overctirne this problem, a wide variety of additive agents such as detergents, anti-oxidants, anti-wear agents, E.P. agents and the like have been proposed for the'iniprovenrent of lubricating oils. Generally, each additive agent is employedto impart aparticular characteristic to the base oil so as to afford a finished lubricating composition which is oxidation'resistant, stable and noncorrosive to bearing metals, and which effectively reduces va rmsh and sludge forming tendencies and minimizes frictional and corrosive wear.

Unfortunately, however, while many of the proposed additive agents improve mineral lubricating oils, quite frequently these'lubricating oil compositions havenot proved to be entirely satisfactory for commercial use since apparently. an additive agent which impartsfa beneficial effect may impart unpredictableand undesirable wear" of a given engine part. For example, a small amount of zinc dithiophosphate displays satisfactory oxidation and bearing corrosion inhibiting properties in a mineral lubricating oil. This additive is particularly active n reducing the corrosion of copper-lead bearings subjected tosevere operating conditions of temperature and pressure. However, a lubricating oil containing a zinc dithiophosphate and a detergent type agent, such as, for example, basic barium mahogany sulfonate, was found to allow excessive wear of parts such as wrist pins, valve lifters and rocker arm shafts in recent models of valvein-head engines. Elimination of the zinc dithiophosphate reduced wrist pin and rocker arm shaft wear but of course the resulting composition wassubject'to oxidative deterioration and the bad effects derived therefrom. The subsequent addition'of an anti-wear agent, i.e. sulfurized sperm oil, to the composition containing the zinc dithiophosphate for practical purposes eliminated wrist pin wear and reduced valve lifter wear but did not solve the rocker arm shaft wear problems. In fact, the anti-wear agent increased rocker arm shaft wear of the base mineral oil. Thus, both the zinc dithiophosphate and the antiwear agent caused excessive wear of the rocker arm shaft and as a result this compounded oil had undesirable properties. Such has been the case when using many additive agents and hence much difficulty has been experienced in formulating an engine lubricating oil of satisfactory anti-wear and anti-oxidant properties.

In accordance with the present invention I have discovered that an improved mineral oil base lubricating composition can be prepared by adding smallamounts of'ni'ckel phenol sulfide and a zinc dithiophosphate'to the base oil and these agents cooperate in 'a uniquetand unexpected manner to inhibit oxidation and deterioration 2,944 020 Patented July 3:"), 1960 of the oil without causing undue Wear of any engine part, e.g. the rocker arm shaft of a valve-in-head engine. Other additive agents such as detergents and anti-wear type agents can also be with advantage included in the lubricating composition. The use of these nickel and zinc components effectively prevent rocker arm shaft Wear and substantially reduce the severe wear which occurs at contact points in rocker arms, tappets and camshaft's. By my invention I have further discovered that the use of these additives will not impart new and undesirable properties with respect to allowing increased wear of a different engine part.

The nickel phenol sulfides employed in the lubricating compositions of the present invention include the 'oilsoluble nickel salts which can be derived from a wide.

variety of alkyl phenol sulfides in which the alkyl or alkyl groups contain from about 8 to 24 carbon atoms. Specific examples of nickel alkyl phenol sulfides which may be employed in accordance with the present invention include, among others, the following: nickel salt of tertiary octyl phenol sulfide, nickel salt of 2-4-diamylphenol sulfide and the nickel salts of C to' C branched chain alkyl phenol sulfides. In my novel lubricating compositions the nickel phenol sulfideis employed in an amount sufficient to provide 0.01 'to 0.20 Weight percent of nickel relative to the mineral oil in which it is incorporated.

The various zinc dithiophosphates which may be incorporated in the lubricating composition'of this invention canbe obtained from a wide variety of dieste'r'dithiophosphoric acids conventionally prepared by reacting'a sulfide of phosphorus, such as phosphorus pentasulfide, with an alcohol, phenol or 'mercaptan. The organic groups in the acid esters may 'be aryl,alkyl, 'aralkyl" or cycloalkyl groups which contain from about 4 to 20 carbon atoms, preferably about 6to 14, and may-be further substituted in the organic portion. Suitable'alcm hols which may be employedin preparing the acid esters include oxo-'alcohols, primary and secondaryalcohols such as-2-methylamyl alcohol, 4amethylpentan'ol-2, Z-methylpentanol-l, 2-ethylhexanol,"di-isopropyl carbinol,'cyclo dioxide*zit-atmospheric"or"slightlyelevated pressure until hexan'ol, butanol-1 and octadecanol-l, or mixtures of high and low molecular weight alcohols. Other hydroxyl containing materials which can be reacted with the phosphorus sulfide include phenols and 'alkylated phenols such as dioctylphenol, tri-isobutylphenol and the'likc.

A particularly suitablezinc dithiophosphate 'which'may be employed to advantage with the nickel sulfonate is the zinc salt obtained from a' mixed dithiophosphate prepared by'reacting a technical mixture of C -s'econdaryand-C primary alcohols, mainlythe former, with phosphorus pentasulfide. The'zinc dithiophosphate is employed in my improved lubricating composition in an amount suflicie nt to inhibit oxidation and bearing corrosion and in most instances the amount used provides about 0.03 to 0.2 percent by weight of phosphorus relative to the mineral oil in which it is incorporated.

A wide variety of compounds utilized as detergentspetroleum suflfonic acids which can be prepared 'by;

neutralization of mahogany sulfonic acids with an-oxide or hydroxide of a metal, for instance an alkaline earth metal, such as calcium or bariumfoxide. 'Preferablythe neutralization is carri ed out to obtain 'a metal' sulfonate" which is alkaline and of higher met-a1 content than the normalfealt. Advantageously, if desired, the basic metal su l fona'te 'can' 'be carbonated by treatmenfWith carthe strong basicity of the sulfonate is reduced from a.

"which it isj derived. 7

The amount'of detergent type agentadded'to the mineral oil base will depend 'upon the nature of the base stock employed and its service application, and in pH of- 14 wtoapH between about 7 'to8., In,the,practice',, a

of this invention the preferred basic barium sulfonate .is prepared by reacting a sulfonated mineral" oil fraction with "at least. about 1.5. times the theoretical amount 'of' -basic bariumoxide required. The basic barium sulfonate is conveni ntl iemploye ja s a concentrate the oilifr om general ranges from about 0.5% to by weight on a'clry sloap basis; In the preferred lubricating composi-' tions' of this invention the ba'sic barium sulfonate is added holates, metalfalkyliphenol sulfides; metal alkyl salicylates, and ithelilre -Thus, in addition to the preferred metal petroleum sulfonates', other detergent addition agentsrsuch as bariurn amyl phenol sulfide, calcium cetyl employed.

- My present compositions can have added an antiiwear agent, particularly to reduce Wrist pin w'ear.- The antisee'd oil,"sulfurized-cotton seed oil and sulfuri zed palm oil. 'A particularly eflective anti-wear type agent employediis sulfurized sperm oil which contains about S V toilS weight percent of combined sulfur. :For antiwear purposes the sulfurized sperm oil is usually employed ina'small or minor amount" suflicient to contribute about in a sufiicient amount to effect a'barium content of about 0.2% to 2.0% by weight. i n Other suitable detergent type jadditives which also can 7 I be used include .rnetal soaps, metal phenates, metal alco w Percent f Barium 3.6 Base No. to pH 4 "13.9

V r -A-vdithiophosphoric acid was prepared by reacting a 'phenate has; pctyl -7 3 may also technical mixture of C secondary and C primary alcohols with phosphorus pentasulfideuntil esterificationwas 1 wear type agents which are preferredare the'sulfurized z fatty'oils ,suchassulfurized sperm oil, sulfurized rape 0.06 to 0.2% by weight of sulfur on the basis of the miner 7 e aloilfo'f. the composition Although the sulfurized pils combat wristpiu' w'ear it apparently promotes rocker arm 7 shaft wear. Surprisingly,-when this additive isjused; in

7 my compositions'containingbotli the zinc dithiophosphate auditlie nickel ph'nol sulfide rockerarm shaft'iw'earis not'-' excessive... The compositionsfof this invention i can contain other additive agents such 5 as pour depres sors'; anti-foam agents and viscosity index improvers.

raThe imine'ral oiIbase stock .used' in the present inven 'tioniis of'lubricating viscosity; 'e.g. 351101225 sus at 7 i210". FI andmay-gbe a solvenfllextract ed or solvent refineddoil obtained in accordance with} conventional The base oil may bev derived from parafiinic, naphthenic, asphaltic or mixed base; cru'de's jandgif desired, aiblend' of solvent treated MidaContinent'neutralsand Mid-Continent bright stocks may be employed., A 'particularly' suitable base'oil used 7 in the preparation'of my c'ompositions'is a solvent treated V *MidContinent "neutral having .a viscosity-linden of ahout'yj" V V The following examples, which are not to be construed,

methods of: treating lubricating oils.

as limiting, are 'offered to further illustrate the novel lubricatingcompositions of thepresent invention 7 Prep'artztionoj r ti cic'el alkyl phenol sulfate V V In the followingimanner, the nickel salt of tertiary? or is a forerunner of excessive wear. I

- typical analysis .of:

.EXAMPIJE n" was freed Tof SOg by'air blowing Jto "leave a solutioniof approximately 10% mahogany sulfonic acids-in oilhavj ing an acid'Noyof 13.0. The acid oil was neutraliied by mixing it with approximately 250% theoretical barium oxide in a water solution for several hours at 180? 'F. followed by dehydration to 300 *F.' The product was filtered with Supercel to obtain a basic barium sulfonate which analyzed as follows:

complete. The acid ester was then reacted with a theoretical amount of zinc oxide at 120 to F. for about 7 3 hours. The mixture was taken up to 250 and held I there for one hour under vacuum. Diluent oil was then added to make about a 60% concentrate which had a Percent Zinc V I .g Phosphorus 7' Sulfur I .7 i -1 LABORATORY ENGINE'IEST" Lubricating oil-blends were preparedcontaining each of'the products prepared ExamPlesfI'j-Iland HL'using as'fareferenceoil an extracted Mid-C I typei-lubn'cating oil SAE 10W: grade. 1 'Ih'eireference'oil j V in each of the compositions tested contained an an'tifoa' nlt,

Preparation of ,basic' bqriun fmahogany isulfonateia A Sweet West Texas gas oil fraction having a viscosity" agent a'nda fpolyni'ethacrylate 'x'ri'scosity indeximproven H "aniIpOurde fe'SsOrE all of the folloj gtests a'standardized 100 hour jcycling' prjo cedur'e was'carriedfoutt on a popular :niake 1955 V-8 valve-in-head engine using a particularf'com-f bination of additive agents {in the reference oil. 'Wearfl of the'i'ocker arm shaft'in these' l00 hour 'tests ured in ten-thousandths ofan; inch. -When these-values]; are quiteflowi a better guide is the'maxinium surface roughness of the loaded areas which can'be measured more accurately. A rough shaft indicates excessive' 'wear -Ifhe following'results-tabulated in Tabled show-that both the zinc dithiophosphateand thesulfun'zed 7 7 dratef(NiGl 6H O) in;2 5 0 grams-of methanol was' 'then i acided whilef stirring the linixtu re at roomitemperature.

Afte'i' stiiring for five minutes longer the" precipitate of bariu'mlchloridewas removed. {The benzene and alcohol 'wereirmoye'd by to'pping and .157 gramsjof a greenish" .LPercent;

Q1]. contribute to rough wearof the rockerarm shaft. I

. TABLE I V e RockerArm Average iTest Composition Shaft Max. Wear-.111-

No. I 7 Roughness, X1O- *Microinches 1 47 Reference'oil! plus zinc dithiophos .70' 1- 2 phateof EXJIII in an'amount to 1 provide 093% P in'total composition', 1.25%sulfurizad sperm oil (12% S) and basic barium .mahogauy sulfonate in an amount to provide .94%-Bai11t0talcomposiion. 7 V 59 Reference oil L r 15 70 Reference oil plus basic barium r 15 .mahogany sulfonate of Ex; II'in an amount to provide 24% Ba in 'totalcomposition. 1 f r 55" Refi-treuce'oil plus'zinc dithiophos f l 38 f .3 phate of Ex. 'IH inan amount to. r i i i pirovide 093% P intotalcomposh i i on; 64 Reference oil kplus 1.25%suliurized 1 40' '0 spermoil.( 12%S).- V 1 2 vlimprover and pour depressor, and unautt-toamagent Reference oil is a SAE iow'base stock containing i methaerylate The results tabulated in Table 11 below show that the addition of the nickel alkyl phenol sulfide of Example I to a lubricating oil containing the zinc dithiophosphate of Example III together with sulfurized sperm oil and basic barium mahogany sulfonate, eifectively overcomes the rough rocker arm shaft wear created by zinc dithiophosphate and the anti-wear agent.

TABLE II being present in an amount to provide about 0.01 to 0.20% of nickel and said dithiophosphate being present in an amount to provide 0.03 to 0.2% phosphorus based on the mineral oil.

2. The composition of claim 1 wherein the mineral lubricating oil is a solvent refined Mid-Continent neutral oil.

Shaft Wear, InsXIO- Test No. Composition App.

Finish, .5 1115.

Shafts Rockers Tappets Cams Max. Av. Max. Av. Max. Av. Max. Av.

47 Reference 011 plus basic barium mahogany C-V sulionate of Example II in an amount to provide 0.9% Ba in the composition, zinc dithiophosphate in an amount to provide 0.09% P, and suliurized sperm oil (0.15

Reference oil 1 plus nickel phenol sulfide of Example I in an amount to provide 0.05% Ni in the composition and zinc dithiophosphate to provide 0.07% P. Basic barium sultonate of Ex. II in an amount to provide 0.9% Ba, and sulfurized sperm oil (0.15% S).

113 S-Cl 1 Reference oil is a SAE 10W base stock containing polymethaorylate VI improver and pour depressor, and an anti-foam agent. I Ccoarse finish; S-smooth finish; V-varnish on surface; Clelean surface.

I claim;

1. A lubricating oil composition consisting essentially of a major amount of a mineral lubricating oil containing minor amounts of oil-soluble nickel alkyl phenol sulfide in which the alkyl group contains about 8-24 carbon atoms, zinc dithiophosphate diester in which the ester groups contain about 4-14 carbon atoms, a sulfurized sperm oil anti-wear agent in an amount sufficient to contribute about 0.06 to 0.2% by weight of sulfur based on the mineral oil, a small amount of basic barium petroleum sulfonate sufficient to impart a barium content of about 0.2 to 2.0 percent by weight, said sulfide References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION 'Patent No. 2,944,020 July 5, 1960 Guy M. Ver-ley I It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 17, for "3.6 percent" read 3.36 percent "I Signed and sealed this 4th day of April 1961.

(SEAL) Attest: ERNEST W. SWIDER V ARTHUR W. (ROCKER Attesting Oificer Acting I Commissioner of Patents

Claims (1)

1. A LUBIRCATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL CONTAINING MINOR AMOUNTS OF OIL-SOLUBLE NICKEL ALKYL PHENOL SULFIDE IN WHICH THE ALKYL GROUP CONTAINS ABOUT 8-24 CARBON ATOMS, ZINC DITHIOPHOSPHATE DIESTER IN WHICH THE ESTER GROUPS CONTAIN ABOUT 4-14 CARBON ATOMS, A SULFURIZED SPERM OIL ANTI-WEAR AGENT IN AN AMOUNT SUFFICIENT TO CONTRIBUTE ABOUT 0.06 TO 0.2% BY WEIGHT OF SULFUR BASED ON THE MINERAL OIL, A SMALL AMOUNT OF BASIC BARIUM PETROLEUM SULFONATE SUFFICIENT TO IMPART A BARIUM CONTENT OF ABOUT 0.2 TO 2.0 PERCENT BY WEIGHT, SAID SULFIDE BEING PRESENT IN AN AMOUNT TO PROVIDE ABOUT 0.01 TO 0.20% OF NICKEL AND SAID DITHIOPHOSPHATE BEING PRESENT IN AN AMOUNT TO PROVIDE 0.03 TO 0.2% PHOSPHORUS BASED ON THE MINERAL OIL.