US2419360A - Lubricating oil composition - Google Patents

Description

- Patented Apr. 22, 1947 LUBRICATING OIL COMPOSITION John G. McNab, Cranford, N. J., Carroll J. Wilson, Norwalk, Conn., and Carl Winning, Westfield, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing.

Claims. 1

This invention relates to lubricating oils and methods for preparing the same, and more particularly to mineral lubricating oil compositions for use as crankcase lubricants in internal com- 'bustion engines.

This application is a continuation-in-part of our co-pending application Serial No. 425,129, filed December 31, 1941.

Because in recent years the requirementsfor .lubricatingoils for gasoline and Diesel engines have steadily been made more stringent, it has been proposed to add various ingredients to these oils to improve-their behavior in such service. On purpose of these ingredients is to impart detergency to the oils, thus bringing about greater engine cleanliness and avoiding ring sticking, carbon formation and varnish deposition. Certain of these ingredients also impart oxidation resistant properties to oils, thereby tending to inhibit the development of corrosive ingredients in [such v oils. 3 agents, areiparticularly required when the oil is to come in contactwith the, newer type of alloys Corrosion-preventing addition.

Application December 21, 1944, Serial No. 569,258

of silver and cadmium and of copper'and lead,

which are now widely used as bearing metals.

It has been found that the addition of small amounts of metal derivatives of organic compounds, such as metallic'phenolates, alcoholates,

I enolates, etc., imparts special detergent properties to such oils, by which the deposition of varnish, sludge and other oil deterioration products on engine parts is prevented and such engine parts are maintained in a high degree. of cleanliness. Unfortunately, on account of their metallic content, these compounds generally increase the corrosiveness of the oil to some extent, although in some" cases they retard the corrosiveness to a minor degree. It has been proposed to add sulfur; nitrogen or phosphorus compounds to oiiset thecorrosiveflaction of the metallic compounds, 'butthese additives tend to'react with the metallic compounds to impair engine cleanliness and to "permit more corrosion than would have been anticipated.

flMoreov'er, in the use of metallic phenolates, alcoholates and the like the. effectiveness of these compounds is gradually spent. The; detergent capacity becomes exhausted as deterioration products, soot-dirt, 'varnish, etc.,'accumulate in the 'lubricantand saturate the adsorptive power of the additive. In engines equipped with a filter, the latter tends to remove the additive, particu- 'larly when the additiveis adsorbed oncontaminationfproductswhichare strained out by the filter. Thepxidation' processes which are underway in 2 an oil during use operate upon the antioxidant functions of the additive and thus also contribute to its exhaustion. The oxidation of the oil also creates insoluble substances which the detergent is called upon to adsorb, thus lessening its capacity for dispersing contamination products which enter the oil, and acidic substancesare also formed which may react directly with; the detergent to destroy its efficacy. When the detergent is employed also to impart corrosion resistant properties to theoil, the above degr'adation phenomena all hasten to break down this corrosion resistance.

It has now been found, in accordance with the present invention, that, by adding to the lubricating oil containing phenolates, alcoholates and the like a second additive comprising the product obtained by alkylating p-cresol with a tertiary alkyl group, the corrosiveness of the oil will be greatly retarded and at the same time the cleanliness of the engine will be found to be even greater than when the metallic compound is used alone. The second compound also affords protection against corrosion even after the detergent has become saturated with dispersed materials or removed by an'oil filter. 1 I

The metallic derivatives of organic compounds which maybe successfuly used in combination with the new class of ether additives may be defined by the formula ROM where. R is an aromatic or aliphatic radical and M is any metal or other basic acting unit, such as a basic radical, but is preferably a metal selected from groups I, II, III, IV, and VIII ofthe periodic table. In this class of compounds the oxygen is attached to a carbon atom which is in turn attached only to carbon, hydrogen or nitrogen. Where M is polyvalent, the additional valences of M maybe joined to other similar RO- groups or to other organic groups or inorganic constituents. i'Ihis class of compounds includes not only the metal phenolates, alcoholates, eno'lates, etc., but also the metal naphtholates and other similar compounds containing more than one benzene, nucleus as well as compounds in which one or more hydrogen atoms of the organic radical are substituted with alkyl, aryl, hydroxyl, I nitro, amino, imino, or. other groups, or substituent atoms such as halogen. It is essential, however, that the compound employed should not contain a carboxyl group attached to carbon in an aliphatic chain, lest, on hydrolysis, an acid strong enough to attack engine parts, despite the presence of the stabilizing compound, be generated. In place of the metals there may be substituted basic radicals, such as ammonium or the various onium groups, such as the quarternary ammonium base radicals or the corresponding sulfonium, phosphonium and similar radicals.

The preferred groups of compounds falling within the above defined class are the phenolates, alcoholates and enolates of metals of groups I, II, III, IV or VIII. Typical examples of these compounds are the following:

A. AlcohoZates.General formula ROM, where R is an aliphatic or substituted aliphatic or nonbenzenoid cyclic radical:

Calcium cetylate, Ca(C12I-I25O)2 Calcium octadecylate, Ca(C1sI-Is1O)2 Barium octadecylate, Ba(C1sI-I3'1O)2 Zinc chlorohexadecylate, ZI1(C16H32C1O) 2 Barium tert.-octyl benzylate,

Oomomo CED-O Cs u CaHn Tin salt of wax alcohols, (CH3(CH2) nCHZO) zSn Magnesium salt of naphthenic alcohols B. Pheno'Zate's.General formula ROM, where R is an aromatic or substituted aromatic radical:

Tin tert.-octyl phenolate,

o-s,.o

CsHn CaHu Calcium iso-dodecyl naphtholate,

Barium p-tert.-amyl phenolate,

OBaO

(351111 CsHu C. Endlates.-General formula whereR and R are organic groups:

Calcium salt of hexyl acetoacetic acid ester,

I LGHaC=C C O O CaHs CeHis 2 Barium salt'of butyl 'acetoacetic acid ester,

| CH3C=C CO 0 C2115 Tin salt of oleyl methyl ketone,

Cobalt salt of amyl benzoyl acetone,

| l CH2C=CHCOCH3 l-csHu Calcium salt of stearophenone,

Barium oleyl amide,

C17HaaC=NH 2 With regard to the alkylated phenolates used 'in this invention, the alkyl radicals should be of sufiicient size to impart adequate oil solubility to the compounds and such alkyl radicals as butyl, amyl, tert.-octyl, decyl, cetyl, and stearyl have been found satisfactory. Whenever the tart.- octyl group is mentioned in this specification, the tetramethylbutyl radical, formed by polymerizing isobutylene, is meant.

When the phenolic groups are alkylated with petroleum olefinic hydrocarbons, such as refinery gases and the like, the resulting products may comprise a mixture of compounds with difierent sizes of alkyl groups.

In some cases the phenolic compounds may be alkylated with long chain groups such as those derived from petroleum wax or an ester wax. In such cases one wax group may be attached to each aryl group or several aryl groups may be attached to one Wax group at several points along the chain, as represented below.

It should be understood, of course, that these are merely examples of the types of compounds which can be formed during alkylation and that the invention is not to be limited by this description.

The second additive which is to be introduced into the lubricating oil composition in accordance with the present invention is a product obtained by reacting p-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylationcatalyst, e. g., sulfuric acid. A satisfactory method for the preparation of one of the preferred additives is as follows: p-Cresol is mixed with about 5% of its weight of 96% commercial sulfuric acid and agitated at about 70 C. while isobutene is bubbled through the mixture. After completion of the reaction, as indicated by the flow of isobutene from the gas exit, the reaction mixture is blown with steam and washed with hot water and dilute. alkaliuntil neutral. A high yield of an oily material is ob.- tained, which readily crystallizes on cooling. The product may be recrystallized from hot alcohol. This product has a molecular weight of about 220, a chemicalcomposition corresponding to the .em-

pirical formula C1 H24Q, and'a' melting point of about '69.2-'69.4 C. The same product may be obtained by reacting p-cresol with tertiary butyl alcohol. I In this case the amount of sulfuric acid catalyst is preferably quite large, i. e., of the order of one mol of catalyst per mol of p-cresol. Temperatures from about 0 C. to about 50 C. may be used, preferably from 25 to C.

v The lubricating oil base stocks 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, sulfur dioxide, furfural, dichloro ethyl ether, propane, 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 voltolized products may be employed, either alone or in admixture with mineral oils.

For the best results, however, the base stock chosen should usually be that oil which without the additive present gives the optimum performance in the service contemplated. 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 oilmust 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 prop erties 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 medium and high speed Diesel engines the general practice has been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of to 90 seconds and a viscosity index of 0 to 50. However, in certain types of Diesel service, and in gasoline engine service, oils of higher. viscosity index are often required, for example, up to '75 or 100, .or even higher, viscosity index.

In addition to the materials to be added accord ing to the present invention, :other agents may also be used such as dyes, pour depressoraheat thickened fatty oils, sulfurized fatty oils, organo metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rub-v ber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waves and 'col-. loidal 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 desire,

able 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, CaHnOH, lauryl alcohol, C12I-I25OH, cetylalcohol, Cisl-lssOH, stearyl alcohol, sometimes referred to as octadecyl alcohoLCisHsqOH, andthe like; the corresponding olefinic alcohols such as oleyl alcohol; cyclic alcohols, such as naphthenic alcohols; and aryl substituted alkyl alcohols, for instance, phenyl octyl alcohol, or octad-ecyl benzyl alcohol or mixtures of these various alcohols, which may be pure or substantially pure synthetic alcohols. One may also use mixed naturally occurring alcohols such as those found in wool fat (which is known to contain a substantial percentage of alcohols having about 16 to 18 carbon atoms) and in sperm oil (which contains a high percentage of cetyl alcohol) and although it is preferable to isolate the alcohols from these materials, for-some purposes the wool fat, sperm oil or other natural products rich in alcohols may be used per se. Products prepared synthetically by chemical processes may also be used, such as alcohols prepared by the oxidation of petroleum hydrocarbons, e. g., parafiin wax. petrolatum, etc.

Generally the amount of each of the additives of the present invention in the finished lubricant composition should be between the approximate limits of 0.02 and 2.0%, and preferably from 0.1 to 1.0%, the exact amount to be used depending to a certain extent on the particular compounds used, the character of the mineral oil base and the operating conditions of the engine in which the lubricant is to be used.

Compositions in which two or more metal compounds are used with one or more of the p-cresol reaction products or in which one metal compound is used with two or more of the p-cresol reaction products are also contemplated in this invention.

The following example shows the effect of the use of a p-cresol, alkylation product upon the corrosion of a copper-lead bearing when used in combination with various metallic compounds of the class defined above, when compared with the results obtained with oils containing the metal compound only,- Included is an example of the use of a calcium soap as the detergent compound instead of a metallic phenolate, alcoholate or similar compound, showing that the new class of corrosion inhibiting additives cannot advantageously be used with all types of detergents.

Example 1 Samples of oil blends containing, separately, the'metal compounds of the present invention as the sole additive and the same compounds in combination with a p-cresol alkylation product,- were submitted to a bearing corrosion test in which the extent of weight loss ofthe bearings due to corrosion by the oils was determined. This test was conducted as follows:

500 cc. of the-oil was placed in a glass oxidation tube (13" long; and 2 diameter) fitted at the bottom with a bore air inlet tube perforated to facilitate air distribution. Theoxidation tube was then immersed in a heating bath so that the oil temperature was maintained at 325F. 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 wasthen immersed in the test oil and rotated at 600 R, P. M., thus providing sufficient agitation of the sample during the test. Air was then blown thrOugh the oil at the rate of 2 cu. ft. per hour. At the end of each four-hour period fresh bearings were supplied and 15% of the oil in the oxidation tube was removed and a corresponding amount of fresh oil blend was added. Each time the bearings were removed they were washed with naphtha and weighed to determine the amount of loss by corrosion. The cumulative weight losses of all the bearings used in a given test at the end of the various four-hour periods are given in Table 1.

Table 1 Cumulative Bearing Weight Loss, mg.

Oil

4 8 Hrs. Hrs.

16 Hrs.

1 Product obtained by reacting p-cresol with isobutcnc.

' It will be noted from the data given in Table 1 that addition of calcium octadecylate made the mineral lubricating oil more corrosive but that when the p-cresol reaction product was added to the compounded oil the resulting blend was even less corrosive than the mineral oil alone. Blends containing a calcium enolate (Oil D) and a barium phenolate (Oil F) were somewhat less corrosive than the mineral oil itself, but in each case the corrosiveness was still further minimized when the additive was added to the blends (Oils E and G). On the other hand, when the p-cresol reaction product was added to an oil blend containing a, calcium soap of a carboxylic acid (Oil H), the corrosiveness was increased rather than decreased (Oil J).

In addition to being employed in crankcase lubricants for Diesel and automotive engines, the additives of the present invention may also be used in light mineral oils such as spindle oils and textile oils, metal cutting oils, turbine oils, insulating and transformer oils, steam cyilnder oils and greases. Also, since these additives achieve their detergent eiTect by modifying surface activity, their use in asphalt, road oils and waxes to improve wetting and adhesive properties is also contemplated. Likewise, they may be added to liquid fuels to increase their wetting ability for metals, enabling them to displace moisture which might otherwise cause corrosion of containers, fuel lines, pump parts, and the like.

This invention is not to be considered as limited by any theory of the action of the various additives nor by any of the examples mentioned or described herein which are given for illustrative purposes only, but it is to be limited solely by the terms of the appended claims.

We claim:

1. An organic composition containing a small quantity, sufiicient to impart detergent properties, of an organic compound of the formula ROM where R is a member of the group consisting of aliphaticand aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a member of the class consisting of metals and basic radicals, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and a small quantity, at least sufficient to offset the corrosive efiect of the first-named compound, of a product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

2. An improved lubricant which comprises an oil base, a small quantity, sufiicient to impart detergent properties, of an organic compound of the formula ROM where R is a member of the class consisting of aliphatic and aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a basic acting unit, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and a small quantity, at least sufficient to ofiset the corrosiveness of the first-named compound, of a product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

3. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of a compound of the formula ROM where R is a member of the class consisting of aliphatic and aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a metal of Group II of the Periodic Table, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and a small quantity, at least sufficient to offset the corrosiveness of the first named compound, of a. product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

'4. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufficient to impart detergent, properties, of a compound of the formula ROM where R is a member of the group consisting of aliphatic and aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a metal of Group II of the Periodic Table, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and a small quantity, at least suflicient to offset the corrosiveness of the first named compound, of the product obtained by reacting para-cresol with isobutene in the presence of an alkylation catalyst.

5. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufficient to impart detergent properties, of a metallic alcoholate and a small quantity, at least suflicient to offset the corrosiveness of the said metallic alcoholate, of a product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

6. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, suflicient to impart detergent properties, of

a metallic enolate which is free from carboxyl and metal substituted carboxyl groups, and a small quantity, at least sufficient to offset the corrosiveness of the said metallic enolate, of a product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

7. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of a metallic phenolate which is free from carboxyl and metal substituted carboxyl groups and a small quantity, at least suificient to offset the corrosive tendency of the said metallic phenolate, of a product obtained by reacting para-cresol with a reagent which furnishes a tertiary alkyl group, in the presence of an alkylation catalyst.

8. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of calcium octadecylate and a small quantity, at least suflicient to ofiset the corrosiveness of the said calcium octadecylate, of the product obtained by reacting para-cresol with isobutene in the presence of a catalytic amount of sulfuric acid.

9. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufficient to impart detergent properties, of the barium salt of cashew nut shell phenol, and a small quantity, at least suflicient to olfset the corrosiveness of the said barium salt, of the product obtained by reacting para-cresol with isobutene in the presence of a catalytic amount of sulfuric acid.

10. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of the calcium salt of the hexyl ester of acetoacetic acid, and a small quantity, at least sufficient to offset the corrosiveness of the said calcium salt, of the product obtained by reacting para -cresol with isobutene in the presence of a catalytic amount of sulfuric acid.

11. A lubricant for internal combustion engines which comprises a mineral oil base, 0.02% to 2.0% of a compound of the formula ROM where R is a member of the group consisting of aliphatic and aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a metal, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and 0.02% to 2.0% of the product obtained by reacting para-cresol with isobutene in the presence of sulfuric acid as a catalyst at a temperature of about 70 C.

12. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of a compound of the formula ROM where R is a member of the group consisting of aliphatic and aromatic radicals which are free from carboxyl and metal substituted carboxyl groups, M is a metal of Group II of the Periodic Table, and the oxygen is attached to a carbon atom which is attached only to carbon, hydrogen or nitrogen, and a small quantity, at least sufficient to offset the corrosive efiect of the first-named compound, of the product obtained by reacting para-cresol with isobutene in the presence of sulfuric acid as a catalyst, said product having a molecular weight of about 220, a chemical composition corresponding to the empirical formula C15H24O, and being, when purified, a white crystalline solid having a melting point of about 69.2-69.4 C.

13. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufficient to impart detergent properties, of calcium octadecylate, and a small quantity, at least suflicient to offset the corrosiveness of the said calcium octadecylate, of the product obtained by reacting para-cresol with isobutene in the presence of sulfuric acid as a catalyst, said product having a molecular weight of about 220, a chemical composition corresponding to the empirical formula 015E240, and being, when purified, a white crystalline solid having a melting point of about 69.2-69.4 C.

14. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of the barium salt of cashew nut shell phenol, and a small quantity, at least sufiicient to offset the corrosiveness of-the said barium salt, of the product obtained by reacting para-cresol with isobutene in the presence of sulfuric acid as a catalyst, said product having a molecular weight of about 220, a chemical composition corresponding to the empirical formula 0151-1240, and bein when purified, a white crystalline solid having a melting point of about 69.2-69.4 C.

15. A lubricant for internal combustion engines which comprises a mineral oil base, a small quantity, sufiicient to impart detergent properties, of the calcium salt of the hexyl ester of acetoacetic acid, and a small quantity, at least sufiicient to offset the corrosiveness of the said calcium salt, of the product obtained by reacting para-cresol with isobutene in the presence of sulfuric acid as a catalyst, said product having a molecular weight of about 220, a chemical composition corresponding to the empirical formula C15H24O, and being, when purified, a white crystalline solid having a melting point of about 69.2-69.4 C.

JOHN G. MoNAB. CARROLL J. WILSON. CARL WINNING.

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

UNITED STATES PATENTS Number Name Date 2,362,293 McNab et a1 Nov. 7, 1944 2,361,051 Patterson et a1 Oct. 24, 1944 2,346,808 Winning et a1 Apr. 18, 1944 2,294,145 Winning et a1 Aug. 25, 1942 2,248,830 Stillson et a1 July 8, 1941 2,202,825 Brandes June 4, 1940