US2420893A - Compounded lubricating oil - Google Patents

Description

Patented May 20, 1947 COMPOUNDED LUBRICATIN G OIL John G. McNab, Cranford, and Charles L. Fleming, Jr., Roselle Park, N. J assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application January 4, 1944, Serial No. 516,978

6 Claims.

This invention relates to lubricants and other organic materials subject to deterioration in the presence of air or oxygen, and it relates more particularly to mineral lubricating oil compositions for use as crankcase lubricants for internal combustion engines and to addition agents suitable for retarding the deterioration of such oils and for improving other properties of the same.

It is known that the addition of certain types of metal-containing organic compounds to lubricating oils improves various properties thereof, such as their oiliness characteristics and their detergent action in engines, particularly manifested in the maintenance of a clean engine condition during operation. Various metal compounds which have been used for such purposes include the metal derivatives of such organic ma terials as fatty acids, naphthenic acids, sulfonic acids, alcohols, phenols, and ketones. However, these various metal compounds generally have the disadvantage of tending to corrode alloy bearings, such as those of cadmium-silver and copperlead, now so widely used in automotive engines; and this is especially true in engines which operate at relatively high speeds and high temperatures. It is an object of the present invention to provide a new class of addition agents for oils which are to be used as crankcase lubricants forinternal combustion engines, the new additives having the primary function of preventing normal deterioration of the oil and of inhibiting any corrosive tendencies of the oil. A further object is to provide addition agents which may be added to lubricating oils containing detergent additives of the types described above, the new compounds being capable of inhibiting any corrosiveness imparted to the oils by such detergent additives. Furthermore, these new materials have of themselves the property of imparting detergent properties to oils to which they are added.

The new class of additives which have now been found to be highly satisfactory fo the purpose described are the metal salts of thiophosphorous and thiophosphoric acids which contain at least one alkylated aromatic sulfide substituent.

These compounds may also be thought of as alkyi phenol sulfides which have been esterified by acid metal salts of thiophosphorous or thiophosphorh acids. Such compounds may be formed by reacting together an alkyl phenol sulfide, a metallir oxide or hydroxide and a sulfide of phosphorus such as phosphorus pentasulfide. By using at alkyl phenol sulfide containing alkyl side chain: of sufficient length to render the compound oilsoluble, the reaction may be conducted readily ir mineral oil solution. When the final product i: to be used as an ingredient in compounded mineral lubricating oils, the aromatic sulfide groul should contain alkyl groups having on the average a total of at least four carbon atoms for eacl aromatic nucleus.

The salts of the class described which are mos generally preferred for use in accordance with th! present invention are the salts of divalent metal; of group II of the periodic table, preferably salt; of calcium, barium, strontium, magnesium or zinc although salts of other metals such as tin, nickel aluminum, etc., are likewise useful. The element selenium and tellurium may also be present a substitutes for sulfur wherever sulfur occurs ii the compound. Aromatic sulfide groups contain ing aromatic nuclei other than benzene nucle may be present. Furthermore, it is intended t1 include as members of the new class of additive compounds in which only one of the hydroxyl o sulfhydryl groups of the phenol or thiophenyl sul fide is esterified with the radical of the acid 0 phosphorus, remaining hydroxyl or sulfhydry groups being either unsubstituted or substitute with a metal or with an ester, ether, aryl, 0 similar group. Such compounds containing meta substituted hydroxyl or sulfhydryl groups may b formed, for example, by reacting a metal mono salt of an alkylated phenol sulfide with a sulfid of phosphorus and an appropriate metal oxide.

It is to be understood that the new class 0 additives includes salts in which one or more 0 the hydrogen atoms of the acid of phosphorus ar substituted by an aromatic sulfide group or th like. Various types of salts illustrative of th ,Jl'esent invention are shown in the following structural formulas, in which M represents a vypical divalent metal and R represents an alkyl group:

lletal derivatives of mono-substituted dithiophosphorous acid:

R'O O \S I! S /P-S 1 g 3 a R a R Similar derivatives of monoand dithiophos- JhOliC acid may be formed, of which the following are examples:

Compounds in which only one of the hydroxyl groups of an alkylated phenol sulfide is esterified by an acid of phosphorus, the other being reacted to form a metal salt or an ester, ether or the like, are illustrated by the following:

In the above formulas R represents at least one alkyl group, M represents a metal atom, and R represents an organic group.

It is to be understood that the above formulas are illustrative only and do not limit the scope of the present invention. For example, one or more of the sulfur atoms attached to the phosphorus atom may be replaced by oxygen, with the provision that at least one sulfur atom remains so attached. Also, the oxygen of the phenol sulfide group may be replaced by sulfur, as in derivatives of thiophenol sulfides. There may also be more than one sulfur atom connecting the two aryl groups, as in polysulfides containing up to four sulfur atoms in the interconnecting group. Also, metals other than divalent metals may be present in the salts. The positions of the various groups in the ring are not to be considered as limited to those shown in the foregoing examples. It should be understood that the additives of the present invention, illustrated by the above formulas, include compounds in which various substituent atoms or groups may be attached to the aromatic nucleus, such as alkyl, aryl, carboxyl, hydroxyl, alkoxy, sulfhydryl, nitro, ester, keto, amino, aldehydo, chlormethyl, amino methyl, alkyl thiomethyl, alkyl xanthomethyl, methyl substituted carboxyl, methyl substituted hydroxyl or sulfhydryl groups, halogen atoms, etc. Alkyl radicals attached to an aromatic nucleus may have a total of four to twenty-four carbon atoms in all of such groups, and in many cases sixteen to twenty-four or more carbon atoms in a single group or a plurality of groups are preferred.

The most preferred compounds of the present invention, that is, the metal salts of the thiophosphorous and thiophosphoric acid diesters of alkylated phenol sulfides may be defined by the following general formula:

in which M is a metal, Ar is an alkylated aromatic group, a is the valence of M, b is 0 or 1, and :z: is 1 to 4. Substituent atoms or groups may be present as mentioned previously.

A convenient and satisfactory method of preparing the preferred compounds of the present invention consists in reacting to ether an alkyl phenol sulfide, a sulfide of phosphorus and a metallic oxide or hydroxide. The sulfides of phosphorus which may be employed include P285, P233, P483 and P487, as well as mixtures of those with sulfur and/or phosphorus. As stated above, when the phenol sulfide contains solubilizing alkyl groups, the reaction may take place in solution in a mineral oil. A light naphtha solvent may be used, and the solvent removed by evaporation after the reaction has been completed; but if the product is to be used as an additive for lubricating oils, it is convenient to cause the reaction to take place in a lubricating oil medium and to prepare a concentrate of the salt in such medium without separation from the solvent. Such concentrates, containing, say, 25% to 75% of additive, are often useful in saving shipping weight and storage space and in facilitating blending operations when preparing the final lubricating oil blend for commercial use. When preparing a concentrate of the type described, it has been found advantageous to add a higher alcohol, such as stearyl alcohol, to the reaction mixture after completion of the reaction in order to facilitate filtration of the final product. In many instances the presence of the higher alcohol is beneficial in the final lubricating oil composition, since it often enhances the detergent and sludge dispersive qualities of the lubricant and aids the solubility of the metal-containing additives and at the same time imparts some oiliness properties to the lubricant.

Among the alkyl phenol sulfides which may be employed as starting materials for the preparation of additives in accordance with the present invention are included tert.-amyl phenol sulfide, tert.-octyl phenol sulfide, diamyl phenol sulfide, cetyl phenol sulfide, octadecyl phenol sulfide, wax alkylated phenol sulfide, octyl cresol sulfide, or the corresponding disulfides or polysulfides or polymers. Also mixtures of mono and polysulfides and/or polymers may be employed. These various phenol sulfides are prepared by reaction of the corresponding alkylated phenol with various proportions of sulfur mono-chloride or dichloride substantially as described in U. S. Patents 2,139,321, 2,139,766, 2,174,248 and 2,198,828.

For preparing the alkylated phenol sulfides suitable alkylated phenols may be obtained by alkylating phenol, cresol, naphthol or other phenolic compounds with such alkylating agents as alcohols, alkyl halides, alkyl phosphates, olefins, terpenes and the like, with the aid of catalysts such as aluminum chloride, boron fluoride, stanm'c chloride and other metal halides, hydrochloric acid, hydrofluoric acid, sulfuric acid, phosphoric acid, activated clay, etc. Conveniently, ole'finic material, such as petroleum refinery gases containing mixtures of olefins, may be used,

or preferably individual olefins may be employed such as butene, pentene or an olefin polyme] such as di-isobutylene or tri-isobutylene. Loy molecular weight polymers of ethylene, propene pentene, or isopentene or mixtures of these ma1 also be utilized in alkylating the phenols. Hig] molecular Weight alkylated phenols may also b employed, for example, those prepared by con densing phenols with chlorinated paraflin was chlorinated petrolatum, or with a chlorinater kerosene or gas oil. Naturally occurring phe nols, such as those obtained by alkaline extrac tion of certain petroleum stocks or those ob tained from cashew nut shell liquid or from othe vegetable sources may likewise be used.

One class of alkyl phenols which are particu larly useful are those which have been preparer by alkylation of phenol with an olefin polyme such as diisobutylene or a refinery butene poly mer oil. Alkylation of phenol with about a1 equimolecular proportion of diisobutylene give para-tert.-octyl phenol, also known as diisobuty phenol or tetramethyl butyl phenol. This phe nolic material is especially desirable because 0 its ease of synthesis and because products mad from it are highly satisfactory for the presen invention. In many instances, however, a highe degree of alkylation may be advantageous and f0 this reason the phenol may be alkylated with a much as two molecular equivalents of diisobutyl ene to give, under proper conditions, essentiall; di-tert.-octyl phenol, or it may be alkylated wit] other olefin polymers such as tri-isobutylene other isobutylene polymers, or a normal buten polymer. The latter type of polymer is obtainer as a by-product in the manufacture of butyl a1 cohol from petroleum refinery butenes. Wine] used as an alkylating agent it gives alkyl phenol having highly branched alkyl groups of abou sixteen to twenty carbon atoms. It should be un derstood that in many cases the alkylation prod ucts may be mixtures of various compound rather than entirely one specific alkyl phenol an that such mixtures may be used in practicing thi invention.

The methods of preparing the new products 0 the present invention and the use of the same i1 lubricating oils are illustrated in the followin examples in which such preparations and uses ar described in detail. These examples are given fo illustrative purposes only and are not to be con sidered as limiting the scope of the invention ii any way.

EXAMPLE 1 221 parts by weight of tert.-octy1 phenol sulfid was dissolved in 365 parts of a solvent extracte Mid-Continent parafiinic oil of 52 seconds vis cosity Saybolt at 210 F. and heated to C with stirring. (The tert.-octyl phenol sulfide wa prepared by alkylation of phenol with diisobutyl ene, followed by reaction with sulfur dichloride The material contained 10.2% sulfur.) Over period of 10 minutes 20.5 parts of ZnO was adde and during the following 15 minutes the tem perature was raised gradually to C. Ove a period of 30 minutes 55.5 parts of P285 (fine than 40 mesh) was added and the temperatur raised to C. There was an evolution c H23 during thi step and the mixture assumed dark brown color. The temperature was raise to C. and stirring was continued for 1 hours to complete the reaction as shown by th Percent Zinc 1.1'7 iulfur 6.60

hosphorus 2.12

EXAMPLE 2 This preparation was similar to that of Exam- )le 1 except that a larger quantity of ZnO was employed. 221 parts of tert.-octyl phenol sulfide prepared as described in Example 1) was dis- :olved in 365 parts of the paraffinic oil described n Example 1. The solution Was heated to 120 3. and 41 parts of ZnO was added over a ninute period. The temperature was raised to 40 C. 55.5 parts of P285 was then added over L 30 minute period; the temperature was then 'aised to 180 C. and held at this point for 2 hours. "3 parts of stearyl alcohol was added and the )roduct filtered through Hyflo filter aid (a dittomaceous earth) giving a mineral oil concenrate of 40% zinc salt of the thiophosphate salt f tert.-octyl phenol sulfide and 10% stearyl al- :ohol. Analysis showed the concentrate to conain the following:

EXAMPLE 3 A solution of 889 parts (2 molecular proporions) of tert.-octyl phenol sulfide (prepared as n Example 1) in 1,465 parts of the paraffinic oil If Example 1 was heated to 120-140 C. Then aver a 30 minute period 81 part (1 molecular n'oportion) of ZnO was added, followed by 222 arts (1 molecular proportion) of P285 during the ollowing 30 minutes. The temperature was then 'aise'd to 180 C. and the heating continued for /2 hours. 252 parts of commercial stearyl al- .ohol was added and the product filtered immedittely to give a solution of 40% zinc thiophosphate :ster of tert.-octyl phenol sulfide and 10% stearyl tlGOhOl. Analysis showed that the mineral oil :oncentrate contained the following:

Percent (inc 1.35

lulfur 6.21

'hosphorus 2.36

EXAMPLE 4 filtrate comprising a solution of the thiophosphoric acid ester of tert.-octyl phenol sulfide.

EXAMPLE 5 One-half of the solution prepared in Example 4 was mixed with 200 cc. of aromatic petroleum naphtha and heated to C. in a 3-necked flask equipped with a stirrer and reflux condenser, the latter being fitted with a trap for the removal of condensed water. Over a 1 hour period 16 grams of Ba(0H)2.8H2O was added, after which heating and stirring were continued for 4 hours at 110 0., when the barium hydrate had become completely absorbed. The product was then filtered giving a clear light brown solution. Removal of the solvent by vacuum stripping gave an oil-soluble transparent solid. The material was redissolved in petroleum ether and dried to give a fine brown solid product, which was the barium salt of the thiophosphoric acid ester of tert.-octyl phenol sulfide.

EXAMPLE 6 The remaining half of the solution from Example 4 was treated in the same manner as in Example 5, except that 5 grams of ZnO was used in place of 16 grams of Ba(OH)2.8H2O. However, after 3 hours of heating at 110 C. there appeared to be no reaction between the zinc oxide and the ester. To facilitate the reaction 200 cc. of Water was added and heating was continued at 110 C. for 16 hours. 500 cc. of benzene was added and the mixture heated under reflux in order to remove water through the reflux trap. The remaining solution was then filtered, using Hyfio filter aid. and th filtrate dried under vacuum at C. The dried product was redissolved in ether, filtered and dried, yielding a zinc salt of the thiophosphoric acid ester of tert.- octyl phenol sulfide as an oil-soluble brown resinous material.

EXAMPLE 7 The corrosion inhibiting properties of the materials prepared as described in the previous examples were determined by adding small quantitles of the products to a lubricating oil base consisting of a solvent extracted Mid-Continent parafiinic oil of 52 seconds Saybolt viscosity at 210 F. and testing the blends so prepared by means of the test method described below. Each blend was so prepared as to contain 1% of the additive salt.

The test for each blend and for a sample of the unblended base oil was conducted as follows: 500 cc. of the oil to be tested was placed in a glass oxidation tube (13" long and 25" diameter) fitted. at the bottom with a /4 bore air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heated bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy and two of cadmium-silver alloy of known weight having a total area of 25 sq. cm. for each alloy were attached to opposite sides of a stainless steel rod which was then immersed in the oil and rotated at 600 R. P. M., thus providing ufficient agitation of the sample during the test. Air was then blown through the oil at 2 cu. ft. per hour. The bearings were washed with naphtha and weighed at the end of a 16 hour period. The weight losses of the bearings are shown in Table I.

1 Bearings gained slightly in weight.

EXAMPLE 8 A further series of bearing corrosion tests were conducted according to the method described in Example '7, except that only the two copper-lead bearing quarters were present, and instead of continuing the tests for one 16 hour period the bearings were cleaned, weighed, and repolished every 4 hours. The base oil used was a Well refined solvent, extracted paraffinic type mineral lubricating oil of S. A. E. 20 viscosity grade. Table II shows the cumulative bearing weight losses that had accumulated at the end of each 4 hour period up to a total of 16 hours.

The Underwood oxidation test was applied to a base oil consisting of a solvent extracted paraflinic oil of 47.5 seconds viscosity at 210 F. and a viscosity index of 113 and to a. blend consisting of the same base oil to which had been added 2.5% of an additive concentrate consisting of 50% each of the concentrates of Example 1 and Example 2. The test was conducted as follows:

The polished bearings of the Underwood machine were thoroughly abraded with emery cloth to expose a fresh surface so that corrosion would proceed uniformly, and then accurately weighed. The apparatus was filled with 1,500 cc. of the lubricant under test and the pump and heater started. The oil pressure was regulated to 10 lbs/sq. in. by means of by-pass valves and maintained at this pressure throughout the test. As soon as the oil had attained the test temperature of 325 F. the heater and pump were turned off just long enough to put the already prepared and weighed bearings in place. Two copper-lead bearing halves were used simultaneously in the test, the bearings being mounted on a polished copper bafiie (2" x 10") which served to catalyze oxidation of the oil. At the end of the test period of 5 hours the hearings were removed, cleaned with naphtha, dried and weighed. A new copper-lead bearing was then placed in the machine and the test conducted for an additional 5 hour period. To accelerate corrosion iron naphthenate in an equivalent of 0.01% F6203 was added to each oil sample. Table III shows the cumulative bearing weight loss for the complete 10 hour run as well as the neutralization number of the oi? and the naphtha insoluble sludge determined a1 the end of the test.

Table III Used Oil Inspections Cumula- Oil tive hearing Weight Naphtha Loss (mg.) Neut. Insolubh No. Sludge, per cent Base Oil 570 7. 6 0.1! Base Oil+2.5% additive concencentratc oi zinc salt 6 2. 0 0. 1

It will readily be seen from the results of the tests of Examples 7, 8 and 9 that the additives oi the present invention are very effective inhibitor: of bearing corrosion when added to lubricating oil compositions. The used oil inspection data 01 Example 9 show that the additives also served tc inhibit deterioration of the lubricating oil.

EXAMPLE 10 In the following tests samples of an unblended base oil consisting of a solvent extracted Coastal naphthenic oil of 60 seconds viscosity (Saybolt) at 210 F. and of the base oil containing 2.5% 01 zinc salt concentrate consisting of 50% each 01 the concentrates of Examples 1 and 2 were tested in a 6-cylinder Chevrolet engine run under high speed and high temperature conditions, namely. 3150 R. P. M., 280 F. oil temperature, 200 F. cooling jacket temperature, and an air/fuel ratio of 14.2/1, for periods of 36 hours. After each test was completed the engine parts were examined and given demerit ratings based on their condition. The individual demerits were weighted and an overall rating calculated from them. The lower demerit rating indicated a better engine condition and hence a better performance of the oil in the engine. The results are shown 1 Gina/bearing of about 50 sq. cm. area.

Although the metal salts of the present invention may be used as the sole additive in lubricating oil compositions, in many instances it will be found of great advantage to employ them in conjunction with other addition agents, particularly with detergent type additives, such as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organophosphates, thiophosphates phosphites and thiophosphites, metal salicylates metal xanthates and thioxanthates, metal phenol sulfonates, metal thiocarbamates, reaction products of metal alkyl phenates and sulfur, reaction products of metal alkyl phenates and phosphorus sulfides, and the like.

Thus. the metal alkyl phenol sulfide thiophosphates and thiophosphites may be used in luzricating oils containing such addition agents as )arium, tert.-octyl phenol sulfide, calcium tertimy phenol sulfide, nickel oleate, barium octalecylate, calcium phenyl stearate, zinc dilsoaropyl salicylate, aluminum naphthenate, cal- :ium cetyl phosphate, barium di-tert.-amyl ahenol sulfide, calcium petroleum sulfonate, zinc nethyl cyclohexyl thiophosphate, calcium dichloostearate, tin naphthenate, aluminum-calcium nixed soap of fatty acids from the oxidation of Jetroleum fractions, barium mahogany sulfoiates, etc.

Particularly advantageous are lubricant com- )ositions in which the additives of the present inention are used in conjunction with metal salts If petroleum mahogany sulfonic acids, with mix- ;ures of the metal sulfonates and metal alkyl )henol sulfides, or with mixtures of the metal sulonates and reaction products of metal phenates ind sulfur.

Examples of such compositions include the folowing:

Il) S. A. E. 30 grade refined lubricating oil containing:

1% barium salt of tert.-octyl phenol sulfide thiophosphite, 1% calcium petroleum sulfonate 12) S. A. E. 20 grade solvent extracted lubricating oil containing:

0.8% zinc salt of tert.-octyl phenol sulfide thiophosphate, 0.6% barium di(tert.-amyl) phenol sulfide, 1.7% mixed calcium-sodium petroleum sulfonates. Z3) Paraflinic lubricating oil containing:

2.3% barium mahogany sulfonates, 1.2% calcium lauryl phenol sulfide thiophosphate. E'l) Mid-Continent lubricating oil containing:

1.5% calcium isohexadecyl phenol sulfide, 0.9% magnesium diamyl phenol sulfide thiophosphite. (5) Pennsylvania lubricating oil (S. A. E.

containing:

1.5% calcium mahogany sulfonate, 0.5% barium salt of C16C20 alkylated phenol sulfide, 0.5% barium salt of ClG-CZO alkylated phenol disulfide, 1.0% zinc tertiary octyl phenol sulfide thiophosphate. I6) Phenol extracted lubricating oil (S. A. E. 10)

containing:

1.0% calcium mahogany sulfonate, 1.0% magnesium isohexadecyl phenate, 1.0% zinc tertiary octyl phenol disulfide thiophosphate. l7) Paraflinic lubricating oil (S. A. E. 30) containing:

1.5% basic calcium mahogany sulfonate, 1.0% calcium octadecylate, 1.0% zinc isohexadecyl phenol sulfide thiophosphate. I8) Solvent extracted Coastal oil containing:

1.5% calcium sulfonate, 0.75% barium tert.-octyl phenol sulfide thiophosphate, 1.0% additive concentrate prepared by reaction of barium tert.-octyl phenate with sulfur.

Method of preparation described in the copending aplication of Dilworth 1. Rogers and John G. McNab, Serial 70. 486,428, filed May 10, 1943.

The following examples demonstrate the use of such additive combinations in interna1 combustion engine lubrication:

EXAMPLE 11 A lubricating oil blend was prepared by adding to a portion of the base oil used in Example 10 a 3-component additive comprising 2.5% of the additive concentrate of Example 3, 1.5% of mixed sodium-calcium petroleum sulfonates (ratio of 1 part by weight of sodium sulfonate to 7.4 parts calcium sulfonate) and 1.16% of an additive concentrate prepared by, reaction of barium tert.-octyl phenate with sulfur at C. (The concentrate contained 40% additive, 10% stearyl alcohol and 50% mineral lubricating oil.) This additive blend was tested in a Chevrolet engine for 36 hours in the same manner as described in Example 10. The following results were obtained:

Table V Engine Demerits Cu Pb Bearing Oil Wt. Loss Ovcr- Rmg all Zone Sludge (Mg) Base Oil 3.37 2.61 4. 63 0. 404 Base 0il+3-Gomponent Additive 0. 26 0. l4 0. 12 0.387

A 3-component additive blend containing the same types of additives in the same proportions and in the same base stock as in Example 11 was subjected to a 126 hour engine test in a single cylinder Caterpillar Diesel engine run under the following conditions: 165 F. oil temperature, cooling jacket temperature, 1000 R. P. M., 19.8 B. H. P. load. Examination of the various engine parts after the test showed that the oil performed much more satisfactorily than a widely marketed commercial heavy duty oil run in the same engine under the same conditions. The results are tabulated below:

Table VI Engine Demerits Oil Tested R ing Overall Z011e Sludge 3-Oomponent Blend 0.46 0.0 0.25 Commercial Heavy Duty Oil 1. 01 0. 84 0.50

those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichloro ethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coal tar fractions and coal tar or shale oil distillates may also be used. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or volatilized products may be employed, either alone or in admixture with mineral oils.

For the best results the base stock chosen should normally be that oil which without the new additives present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The on must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds Saybolt viscosity at 210 F. For the lubricating of certain low and medium speed Diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatio crudes and having a Saybolt. viscosity at 210 F. of 45 to 90 seconds and a viscosity index of to 50. However, in certain types of Diesel service, particularly with high speed Diesel engines, and in aviation engine and other gasoline engine service, oils of higher viscosity index are often preferred, for example, up to 75 to 100, or even higher, viscosity index.

In addition to the materials to be added according to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, 'and the like may also be employed.

Assisting agents which are particularly desirable are the higher alcohols having eight or more carbon atoms and preferably 12 to 20 carbon atoms. The alcohols may be saturated straight and branched chain aliphatic alcohols such as octyl alcohol (CaHrzOH), lauryl alcohol cetyl alcohol (C1sHs3OI-I), stearyl alcohol, sometimes referred to as octadecyl alcohol,

heptadecyl alcohol (C1'IH35OH), and the like; th corresponding olefinic alcohols such as oleyl alco hol; cyclic alcohols, such as naphthenic alcohols and aryl substituted alkyl alcohols, for instance phenyl octyl alcohol, or octadecyl benzyl alcohc or mixtures of these various alcohols, which ma; be pure or substantially pure synthetic alcohols One may also use mixed naturally occurring alco hols such as those found in wool fat (which 1 known to contain a substantial percentage of al cohols having about 16 to 18 carbon atoms) am in sperm oil (which contains a high percentag of cetyl alcohol); and although it is preferabl to isolate the alcohols from those materials, fo some purposes, the wool fat, sperm oil or othe natural products rich in alcohols may be use per se. Products prepared synthetically by chem ical processes may also be used, such as alcohol prepared by the oxidation of petroleum hydro carbons, e. g., paraffrn wax, petrolatum, etc.

These assisting agents serve to enhance th detergent and sludge dispersive qualities and ail the solubility of the metal-containing additive and at the same time impart some oiliness prop erties to the lubricating oil compositions,

In addition to being employed in crankcas lubricants the additives of the present inventioi may also be used in extreme pressure lubricant: engine flushing oils, industrial oils, general ma chinery oils, process oils, rust preventive compo sitions, and greases. Also their use in motor fuels Diesel fuels and kerosene is contemplated. A par ticular application in this regard is their use i1 motor fuels containing tetraethyl lead or othe anti-knock agents, the additives of the presen invention serving not only as antioxidants for th fuel but also as stabilizers for the anti-knocl agent itself. Since these additives exhibit anti oxidant properties and are believed also to posses ability to modify surface activity, they may b employed in asphalts, road oils, waxes, fatty oil of animal or vegetable origin, soaps, and plastic: Similarly, they may be used in natural and syn thetic rubber compounding both as vulcanizatioi assistants and as anti-oxidants, and genera-ll they may be used in any organic materials sub ject to deterioration by atmospheric oxygen.

The present invention is not to be considere as limited by any of the examples describe herein which are given by way of illustration only but it is to be limited solely by the terms of th appended claims.

We claim:

1. A mineral lubricating oil containing a stabi lizing quantity of a metal salt of a thiophosphori acid ester of an octyl phenol sulfide.

2. A mineral lubricating oil containing a stabi lizing quantity of a zinc salt of a dithiophosphori acid ester of a tert.-octyl phenol sulfide.

3. A mineral lubricating oil containing a stabi lizing quantity of a barium salt of a dithiophos phoric acid ester of a tert.-octyl phenol sulfide.

4. A method of preparing a lubricating oil con centrate containing a zinc salt of a dithiophos phoric acid ester of a tert.-octyl phenol sulfid which comprises dissolving the tert.-octyl phem sulfide in a mineral lubricating oil and heatin the solution thus formed in the presence of zin oxide and phosphorus pentasulfide at a temper ature of to C.

5. The method of preparing a lubricating o concentrate containing about 40% of the zin salt of a dithiophosphoric acid ester of a tert. octyl phenol sulfide which comprises dissolvin about two molecular proportions of tert.-oct:

henol sulfide in a suitable quantity of a mineral ibricatlng oil, heating the solution thus formed about 120 to 140 0., adding about one moleclar proportion of zinc oxide and about one iolecular proportion of phosphorus pentasulfide nd heating at about 180 C. until the solid rectants are substantially completely absorbed in no solution, adding about 10% by weight of tearyl alcohol, based on the total weight of the lixture, and filtering the solution, the amount of ibricating oil solvent used being suificient to arm a concentrated solution which, after filterig, contains about 40% by weight of the zinc ilt formed in the reaction.

6. The method of preparing a barium salt of dithiophosphoric acid ester of a tert.-octyl henol sulfide which comprises dissolving about two molecular proportions of a tert.-octyl phenol llfide in a petroleum naphtha, heating the soluon under reflux while gradually adding about he molecular proportion of phosphorus pentailfide, continuing the refluxing of the solution ntil the phosphorus pentasulfide is substanally completely absorbed, filtering the resultig solution, heating the solution further under reflux in equipment provided with means for the removal of condensed water while adding gradually about one-half molecular proportion of Ba(OH) 2.3H2O, continuing the refluxing until the barium compound is substantially completely absorbed, filtering the resulting solution and removing the solvent by evaporation.

JOHN G. MCNAB. CHARLES L. FLEMING, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS