US2483505A - Compounded lubricating oil - Google Patents

Description

Patented Oct. 4, 1949- COMPOUNDED LUBRICATING OIL Dilworth '1'. Rogers, Summit, and John G. McNab, Cranford, N. 1., asslgnors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 30,1944,

Serial No. 570,742

7 Claims. (01. 252-421) 1 This invention relates to lubricants and other organic materials subject; to deterioration in the presence of 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.

This is a continuation-impart of our co-pendlng applications Serial Number 486,428, filed May 10, 1943, issued as Patent No. 2,406,564, granted August 27, 1946, and Serial Number 547,640, filed August 1, 1944, issued as Patent No. 2,409,687, granted October 22, 1946.

The addition agents themselves, considered as new compositions of matter, are claimed separately in co-pending application Serial N0. 101,-- 498, filed June 2, 1949, which is a division'of the present application. v

It is known that the addition of certain types of metal 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 compounds 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 for internal combustion engines and which exhibit the desirable properties of promoting engine cleanliness, improving oil film strength, reducing ring sticking, piston skirt varnish formation and the like, and which not only do not exhibit the corrosion promoting tendencies characteristic of the above metal compounds but also inhibit the corrosiveness of the oils to which they are added.

It was disclosed in the aforementioned copend ng application Serial Number 486,428 that the products obtained by the reaction of elemental sulfur with metal phenates and thiophenates are very satisfactory additives for mineral lubricating oils, since they are valuable detergents and at the same time do not exhibit 2 the corrosiveness characteristic of many detergent additives known to the art. Similarly, in co-pending application Serial Number 547,640, it was disclosed that the reaction products of elemental sulfur with metal salts of hydroxy and mercapto substituted aromatic sulfides were very valuable lubricating oil additives. It was also d sclosed in'both of the aforementioned co-pending applications that valuable products could be formed on reacting the sulfur not only with the normal metal salts of phenols, phenol sulfides and the like, but that, in place of the normal salts, basic salts, containin a, greater proportion of metal in the compound than is present in a compound in which all of the valences of the metal are satisfied by the organic groups, may likewise be used. The use of these basic metal salts to form new products by reaction with elemental sulfur, and the use of such products as additives for lubricating oils and as antioxidant materials generally for organic materials from the subject matter of the present invention. In accordance with this invention, not only the metal phenates and metal salts of phenol sulfides and the like, but any basic metal salt of an acidic organic compound may be reacted in a similar manner to form valuable additives,

' which meet the requirements for a satisfactory the like. It is believed that the basic salts have at least one hydroxyl group attached to the metal atom which has replaced the hydrogen of a hydroxyl or sulfhydryl group. Therefore, only polyvalent metals can be present in such salts.

The new products of the present invention are adaptable to use with a wide variety of petroleum lubricating 011 base stocks. They are also useful as antioxidants and have other purposes when incorporated in organic materials other than lubricating oils, as will be more fully explained hereinafter. The materials are also useful as agents for imparting extreme pressure properties to lubricants, wherein the film strength of the lubricant is greatly increased by the presence of the additives. Furthermore, certain of the additives, particularly those containing waxalkylated aromatic groups, will be found to be useful as pour depressors.

3 The new products of the present invention may be more accurately defined as the products obtained by reacting elemental sulfur with a compound having the characterizing structure (RX) mM(OH) a in which R is an organic group, X is oxygen, sulfur, selenium or tellurium, M is a polyvalent metal, and m and n are small integers whose sum is equal to the valence of M. It is to be understood that where more than one RX group is present, these may be alike or difierent, and that M may be attached to more than one X atom, two or more of which may be attached to the same organic group. M of the formula may be any polyvalent metal, such, for example, as calcium, barium, strontium, aluminum, zinc, tin, cobalt, nickel or magnesium, but the divalent metals of group II of the periodic table are especially preferred.

Several of the more important classes of basic metal salts of acidic compounds which may be reacted with sulfur in accordance with the present invention are illustrated by the compounds whose formulas are shown below.

Basic barium alcoholate (R =elkyl) i-aslc barium mercaptide (R =allryl) Basic calcium allryl phenate (R=alkyl) Basic barium alkyl phenol sulfide (R=alkyl), 11:1 to 4 Basic calcium sulfonate (R=alkyl or alkaryl or petroleum hydrocarbon group) Basic barium suiionate (R=alkyl or alkaryl or petroleum hydrocarbon group) In the case of compounds having more than one OH or SH group in the molecule, for example alkyl phenol sulfides or dihydric phenols, it is possible to prepare basic metal salts having various ratios of metal to organic groups. As an illustration, a basic metal salt of an alkyl phenol In the case of a 1.5:1 ratio the formula may be MOH MOH O O-M-O O as as In the case of a 3:1 ratio the formula may be lgon llOH Intermediate ratios of metal to phenol sulfide,

' "such as 1.8:1 or 2.3:1, may occur in which mixtures of. the above types of basic compounds are obtained.

In addition to the basic salts prepared from divalent metals, basic metal salts formed from trivalent metals may be used, such salts being illustrated by the following general formulas:

xn x11 M cs win on \OH in which M is a trivalent metal, X is oxygen or sulfur, and R is an organic group. I

The following types of compounds are the more important acidic compounds which may be used to form basic metal salts which in turn are reacted with free sulfur to form the new additives of the present invention: alcohols, mercaptans, carboxylic acids (e. g., fatty acids, naphthenic acids, alkylated benzoic and salicylic acids) sulfurized unsaturated acids, alkylated phenols, alkylated naphthols, alkyl phenol sulfides and polysulfldes, alkyl naphthol sulfides and polysulfides, sulfonic acids (e. g., petroleum sulfonic acids, alkyl aromatic sulfonic acids and alkyl phenol sulfonic acids, alkyl phenol sulfide sulfonic acids), xanthic acids, dithiocarbamic acids, organo substituted acids of phosphorus (e. g., phosphorous, phosphoric, phosphonic, and phosphinic acids and the corresponding thio acids), etc.

It is to be understood that in any of the above types of compounds the organic radicals may contain various substituted atoms or groups such as alkyl, cycloalkyl, aralkyl, aryl, carboxyl, hydroxyl, alkoxy, aroxy, sulfhydryl, nitro, ester (organic and/or inorganic), keto, amino, aldehyde, chloromethyl. aminomethyi, alkyl thiomethyl, alkyl xanthomethyl, metal substituted carboxyl, metal substituted sulfo, metal substituted hydroxyl or sulfhydryl groups, halogen atoms, etc.

One method for converting the acidic compounds to basic metal salts consists merely in adding a metallic oxide or hydroxide to a solution of the acidic compound in a quantity greater than that required to form the normal salt, the reaction generally being conducted at an elevated temperature.

It may be found that in some cases not all of the metallic base which has been added for the purpose of forming a pure basic metal salt will react with the organic compound. How ever, substantial quantities of the metal base, above that required to form a normal salt, will usually react, and the product may therefore consist of a mixture of the normal salt and the basic salt. It. is to be understood that the invention includes the use of such mixtures as well as pure basic salts in the subsequent reaction with sulfur.

Specific examples of compounds which may be treated with sulfur in accordance with the present invention include, among others, the following: basic barium salt of tert.-octyl phenol sulfide, basic calcium sal of cetyl phenol, basic barium salt of wax-alkylated phenol or salicylic acid, basic zinc salt of methylcyclohexyl thiophosphoric acid, basic calcium petroleumsulfonates, basic barium salt of 2,4-diamylphenol sulfide, basic magnesium salt of octadecyl alcohol, basic aluminum salt of phenylstearic acid, and basic barium salt of Cit-C24 branched chain alkyl phenol sulfides.

In accordance with the present invention, the

basic metallic salt of the acidic organic compound or other metal salt containing excess metal, is caused to react with sulfur. This may be accomplished by adding'the sulfur in elemental form to a heated solution of the salt. Sulfur may beused in any of its allotropic forms.

In carrying out the reaction described above the proportions of sulfur and metal salt are so chosen that from 0.1 to 2.5 atomic proportions of sulfur are reacted with one atomic proportion of metal, the preferred ratio being within the limits of about 0.5 to 1.5 atomic proportions of sulfur for eachatomic proportion of metal. This preferred ratio givesthe'products the optimum content of sulfurto impart to them the maximum amount of inhibiting power.

If desired. certain of the products used in accordancewith this invention may be prepared by the simultaneous reaction of an acidic material, a metallic oxide or hydroxide, and elemental sulfur. However, it is generally preferred to first form the basic metal salt and then reactthis with'sulfur.

Although the reaction can be brought about by heating the metal salt directly with sulfur, it is more convenient to carry out the reaction with the aid of solvents, particularly high boiling hydrocarbon solvents, such as xylol or a petroleum fraction. A particularly preferred reaction medium is a lubricating oil fraction, since the final reaction product may thus be obtained as a mineral oil concentrate of the desired additive, which may be conveniently shipped or stored as such and then readily blended with a lubricating oil base stock in the desired concentration to form a finished lubricating oil blend. Further conditions for conducting the reaction are discussed in detail in the specifications of the aforementioned copending applications.

Generally, the additives of the present inven extent on the particular products used, the.

nature of the lubricating oil base stock and the operating conditions of the engine in which the lubricant is to be employed. This same general jrange of concentration will also be effective when the additivesare to be used in greases and in extreme pressure lubricants, although in the latte instance greater amounts, up to 20%, may be employed. As has been pointed out elsewhere in the specification. it isv oftentimes convenient to prepare concentrates of the additive in oil, containing, say, 25% to 75% of the effective addition agent, the concentrate later being added I to a suitable lubricating oil base stock to give a EXAMPLE 1 PREPARATION or BASIC BARIUM TERT.-OCTYL 'PHENOL SULFIDE A mixture of 7,740 grams of tert.-octyl phenol sulfide, 13,500 grams of SAE 20 grade mineral lubricating oil and 1,500 grams of stearyl alcohol was placed in an 8 gallon reactor and heated to 120-125 C. with stirring and blowing with nitrogen. Over a period of 16 hours of heating and stirring 9,000 grams of barium hydroxide, Ba(OH)z.8HzO, was gradually added. Heating was continued for 8 hours and the temperature was then raised to l40-145 C. and the product was filtered, giving a mineral oil concentrate containing approximately 40% basic barium tert.- octyl phenol sulfide, 6% stearyl alcohol and 54% mineral lubricating oil. Analysis of the concentrate: 12.95% barium, 3.13% sulfur.

EXAMPLE 2 contain 4.24% sulfur.

EXAMPLE 3 A mixture of 412 parts of tort-octyl phenol, 203 parts of commercial stearyl alcohol, and 1015 par of an SAE 20 grade refined parafi'inic mineral lubricating oil was heated to C. after which 660 parts of Ba(OH) 2.81120 was added over a period of 3 hours; Then 128 parts of sulfur was added and the temperature held at 120 C. for an additional hour, after which the product was filtered to give a concentrate containing about 41% of addition agent. Analysis: 12.99% barium and 6.24% sulfur.

EXAMPLE 4 This preparation is similar to that of Example 3 with the exception that the basic metal phenate had an even greater excess of barium than that of the former example.

Over a period of 2 hours 945 parts by weight of Ba(OH)2.8H2O was added to a mixture of 412 parts of tert.-octyl phenol, 203 parts of commercial stearyl alcohol and 1015 parts of an SAE 20 grade refined paraflinic mineral lubricating oil, the temperature being maintained at 150 C. The temperature was then raised to 1-80-l90 C. for one hour, lowered to 150 C. long enough to permit the addition of 128 parts of sulfur and then raised to l80-190 C. for an additional hour. The product was filtered, giving a dark colored concentrate containing about 43% of additive in mineral oil. Analysis of the concentrateshowed it to contain 17.83% barium and 5.79% sulfur.

EXAMPLE 5 Blends of each of the concentrates of Examples 1 and 2 were prepared in a solvent extracted Mid- Continent parafiinic oil \52 seconds Saybolt viscosity at 210 F), 2.5% of the concentrates being employed so that in each finished blend approximately 1% of actual additive was present. Each of these blends was subjected to a bearing corrosion test conducted as follows: 500 cc. of oil to be tested was placed in a glass oxidation tube (13" long and 2%" diameter) fitted at the bottom with a A" 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 of known weight having a total area of 25 sq. cm. 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 suflicient agitation of the sample during Table BEARING CORROSION TESTS Mg. Bearing Additive in Oil Blend Weight Loss in 16 Hours lroduct of Example 1 73 Product of Example 2. 43

Although in most instances the additives of the present invention will of themselves impart v suiiicient improvement to lubricating oils to give very satisfactory results, still greater improvement may be obtained by employing these addition agents in conjunction with other additives of the detergent type, such as metal soaps, metal phenates, metal alcoholates, metal phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal sulfonates, metal thiocarbamates, metal xanthates and thicxanthates, and the like.

The additives of the present invention may be used in conjunction with any of the additional additives mentioned in application Serial Number 486,428 or Serial Number 547,640.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from parafiinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly 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, sulfurdioxide, furfural, dichloro ethyl ether, nitrobenzene, crotonaldehyde, etc.

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 optimumperformance 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 oil 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 lubrication 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 aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to seconds and a viscosity index of 0 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, sludge dispersers, antioxidants, thickeners, viscosity index improvers and any of the agents commonly used as additives, a number of which are disclosed in application Serial Number 486,428. Of special importance are the higher alcohols having eight or more carbon atoms per molecule. The latter agents serve to enhance the detergent and sludge dispersive qualities and aid the solu bility of the metal containing additives and at the same time impart some oiliness properties to the lubricating oil composition.

In addition to being employed in crankcase lubricants the additives of the present invention may also be used in extreme pressure lubricants, engine flushing oils, industrial oils, general machinery oils, process oils, rust preventive compositions, and greases. Also their use in motor fuels, Diesel fuels and kerosene is contemplated. A particular application in this regard is their use in motor fuels containing tetraethyl lead or other anti-knock agents, the additives of the present invention serving not only as antioxb dants for the fuel but also as stabilizers for the anti-knock agent itself. Since these additives exhibit antioxidant properties and are believed also to possess ability to modify surface activity, they may be employed in asphalts, road oils, waxes, fatty oils of animal or vegetable origin, soaps, and plastics. Similarly, they may be used in natural and synthetic rubber compounding both as vulcanization assistants and .as antioxidants, and generally they may be used in any organic materials subject to deterioration by atmospheric oxygen. 4

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

We claim:

1. A compounded lubricant comprising a mineral lubricating oil base and 0.02% to 20% of a product obtained by reacting elemental sulfur with a basic polyvalent metal salt of an alkylated phenol sulfide having at least 5 carbon atoms in each alkyl group at a temperature of 90 to 210 C., the proportional reactants being such that 0.1 to 2.5 atomic proportions of sulfur are present for each atomic proportion of metal.

2. A compounded lubricant according to claim 1 in which the metal of the metal salt is a divalent group 11 metal.

3. A compounded lubricant according to claim 1 in which the metal of the metal salt is barium.

4. A compounded lubricant according to claim 1 1 in which the alkylated phenol sulfide is tertoctyl phenol sulfide.

5. A compounded lubricant according to claim 1 in which the metal or the metal salt is barium and in which the alkylatedphenol sulfide is tert.- octyl phenol sulfide.

6. A concentrate consisting essentially of a mineral lubricating 011 containing dissolved therein 25% to of a product obtained by REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATEN'I'B Number Name Date 2,346,157 Farrington et al. Apr. 1, 1944 2,360,302 Etzler et al Oct. 10, 1944 2,406,564 Rogers et al Aug. 27, 1946