US2342027A

US2342027A - Inhibited oil

Info

Publication number: US2342027A
Application number: US389169A
Authority: US
Inventors: Stanley P Waugh
Original assignee: TIDE WATER ASSOCIATED OIL COMP
Current assignee: TIDE WATER ASSOCIATED OIL Co; TIDE WATER ASSOCIATED OIL COMP
Priority date: 1941-04-18
Filing date: 1941-04-18
Publication date: 1944-02-15
Anticipated expiration: 1961-02-15

Description

Patented F b. 15, 1 944 UNITED STATES PATENT OFFICE Stanley P.

Waugh, Westfield, N. 3., assignor to Tide Water Associated Oil Company, New York, N. Y., a corporation of Delaware No Drawing. Application April 18', 1941, Serial No. 389,169

21 Claims.

prevail and a thin film of oil is in contact with hot meta1 surfaces, as in the lubrication of internal combustion engines, or where the oil is used in oxidizing atmospheres or at elevated temperatures, as in transformers, in cable wrapping and metal cutting operations the oil may tend to deteriorate.

Another factor which influences the value and service life of lubricants, especially oils used for the lubrication of internal combustion engines, is the degree of corrosive effect which the oils exert upon the bearing surfaces in the engine. Engine bearings of cadmium-silver, cadmium-nickel or copper-lead alloys are now frequently used instead of the more conventional Babbitt metal bearings. Experience with bearings of the character of cadmium-silver, cadmium-nickel, and copper-lead has proved that they are extremely susceptible to rapid deterioration in service when lubricated with many available lubricating oils, particularly lubricating oils considered by conventional criteria as being superior in other respects.

Mineral oils are improved as respects deterioration characteristics by refining methods which remove or convert, at least in part, certain deterioration constituents normally present therein. @efining with chemicals, as with selective solvents of the character of phenol, liquid sulfur dioxide, nitro-benzene, iurfural, and others, by clay filtration or by treatment with sulfuric acid, is often resorted to. The refined products, however, still are susceptible to oxidation, polymerization or other change to which may be attributed impairment of the oil as indicated by acid and sludge formation, color degradation,-. inordinate viscosity increase or tendency to cause corrosion of the above stated alloy bearings. Conditions often observed in internal combustion engines after long running at sustained high speeds,

by the conditions ob---, taining during use. Where high temperatures such as stuck piston rings, clogged ring grooves and oil holes and general deposition of "varnish". on the various parts of the motor, particularly when many or the lower viscosity motor lubricating oils are employed as the lubricating medium, have been attributed to deterioration of the oil.

It is an object of the present invention to retard or inhibit the deterioration of mineral oils. Another object is to retard or inhibit the corrosive deterioration of cadmium-silver, cadmiumnickel, copper-lead or like bearings by refined mineral lubricating oils.

A further object is to provide effective inhibitors for lubricating or like oils of petroleum ori- A more specific object is-to provide mineral lubricating oils containing in amounts eflfectlve to retard or inhibit deterioration of said oils and corrosion of cadmium-silver and like bearing alloys, salts of esters of sulphocarboxylic acids. Another object is to provide engine lubricating oils having satisfactory lubricating properties and low vamish depositing characteristics at high oil temperatures and sustained engine speeds.

Other objects and advantages will appear from the following description of the invention and I the illustrative examples.

Illustrative of inhibitors which may be used according to the present invention and one which has shown to be particularly effective is the calcium salt of dioctyl ester of sulphosuccinic acid, otherwise known as calcium dioctyl sulfo succinate. The high eiiectiveness of this substance when incorporated in small amounts in engine lubricating oil is demonstrated by the following tests.

The runs were made with an internal combustion engine lubricating oil of 10 S. A. E. viscosity rating comprising a blend of solvent refined Pennsylvania neutral oil with a conventionally produced Pennsylvania bright stock. This grade of oil has in many instances caused ineilicient engine operation and sometimes complete engine failure due to its tendency to cause varnish" deposits in service. The engine used for the tests was an overhead-valve six cylinder automobile engine. In each case the engine was run at a substantially constant speed of 3150 R. P. M. (equivalent to miles per hour) under a load of 35 brake horsepower. During the runs the oil temperature was maintained at 280 F. and the water jacket temperature at 200 F.

In the first test the engine which had been thoroughly cleaned inside was run for an equivalent of 2500 miles under the stated conditions using as the lubricating oil the uninhibited Pennsylvania S. A. E. oil described above. At the end of this run the oil was drained and the motor disassembled for inspection. Largeamounts of vamish-like material were found deposited on the inside walls of .the engine, piston skirts. crankshafts and other moving parts. The oil screen was partially blocked with deposited sludge and the ring slots and oil holes in the pistons were partially blocked with solid material.

The engine was then thoroughly cleaned of deposited material and re-assembled. In the next run a resh supply of the same S. A. E. 10 oil to whic 1.0% by weight of the calcium salt oi dioctyl ester of sulphosuccinic acid had been added was used. The engine was run under the same conditions as in the first run except that it was stopped and disassembled after an equivalent of 3000 miles instead of 2500 miles. The effect of the small amount of inhibitor was apparent from an inspection of the inside of the motor. The inner walls of the motor and the crankshaft were substantially clean and free from solid deposit. Only a very thin layer of varnish had deposited on portions of the piston skirt. Only a small amount of sludge appeared on the cover plates. The oil pump screen was clean and unblocked, and the ring slots and oil drain holes were clean and unblocked. The motor, after this run with inhibited oil was characterized by its generally clean condition as compared with its condition after the first run using uninhibited oil.

The presence of certain polar groups in the molecule of compounds of this invention is im portant. The polar carbonyl group, and particularly the sulfonate polar group, appears to impart film strength and other desirable film characteristics, such as aiding in the formation of a strongly adsorbed protective film upon the hearing surfaces and other corrodible parts. Free acid radicles are in general to be avoided, particularly when the oil is to be used in motors equipped with alloy bearings, since a free acid would tend to promote corrosion.

Many compounds containing sulfonate groups, however, are notsufllciently soluble in oil and thus cannot be used as inhibitors. The compounds of this invention which contain the ester linkages in addition to the sulfonate group are soluble. Further, I have found that salts of the stated sulfo esters which contain branched chain alkyl groups are more oil soluble than those of unbranched chain structure. The branched chain compounds are therefore preferred. Ex-

, amples of suitable branched chain compounds suitable for use in this invention are the salts of di-isoamyl, di-isooctyl and di-heptadecyl esters of sulfo di-carboxylic acids. The salts of branched chain esters of sulfo monocarboxylic acids are likewise more suitable than the unbranched chain esters of the corresponding acids for the same reason. Since, however, more branched chains can be added by esterificatlon of the dicarboxylic acids than by esteriflcation of the monocarboxylic acids the dicarboxylic acid esters are preferred as being more oil soluble.

Inhibitors within the contemplated scope and practice of the invention include not only the salts of esters of sulfo-dicarboxylic acids in which the hydrogen of the carboxyl groups have been substituted by like alcohol radical residues as in the case of calcium diactyl succinate, but also include mixed esters in which said hydrogens 7 number of carbon atoms are substituted by dissimilar radicals. Likewise the invention is not to be considered limited to use of the calcium salts of these esters, since other alkaline earth salts, the alkali metal salts, as well as other metal salts such for example as aluminum are suitable, as will be shown hereinbelow. In general, any salt of the stated esters effective as an inhibitor for mineral oils is contemplated as being within the scope of the invention.

Examples of other esters which have been found to give good results as inhibitors according to this invention are the salts of lauryl, amyi and octyl alcohol esters of the sulfodicarboxylic acids.

In most cases the presence of a fraction of one percent ofthe inhibitor in the mineral oil will produce the desired result. Although such small percentages are generally useful in the practice of the invention, it should be understood that larger proportions of inhibitors may be used as deemed desirable. Satisfactory results are generally obtained when using the inhibitors in maximum amounts of the order of 1% by weight in the oil.

One outstanding characteristic of the described compounds is their tendency to emulsify mixtures of oil and water. These compounds are therefore generally not suitable for use in lubricating oils which in service are contacted with water, such as in the lubrication of turbines, where excessive and objectionable foaming may result from emulsificationof the oil with water present. The problem of excessive foaming and emulsiflcation is generally not encountered in the lubrication of internal combustion engines with oil containing the inhibitors of this invention due to the relatively small amounts of water present in the crankcase. In some instances, however, internal combustion engines are operated under conditions conducive to the formation of larger amounts of water in the crankcase than are formed in ordinary service. It is therefore preferred to use as the inhibitor the alkaline earth salts, or the metallic salts such as aluminum, of the esters stated. in lieu of the alkali metal salts, since the former are less water-soluble than the latter and have less tendency to cause formation of troublesome emulsions.

Likewise I have found it preferable to use as inhibitors in engine lubricating oils and the like the salts of those esters having residual alcohol radicals of a relatively low number of carbon atoms. I have found that, in general, the lower in the residual alcohol tendency toward foaming in service. Thus, for example, the compounds of the stated type which contain residual alcohol radicals of from about 5 tom carbon atoms are preferred over those compounds containing residual alcohol radicals of more than 10 carbon atoms since the former show less tendency to form emulsions and cause foaming in service than the latter.

The utility of my inhibitors when used in internal combustion engine lubricating oils in preradical, the less is the venting or retarding corrosion of cadmium-silver" service conditions with the bearings of cadmiumsilver and like alloys than exists in use of Babbitt bearing may be a. factor involved in bearing corrosion. The presence of copper in the form 45.9, viscosity at 100 F. 18.2, color 3.25. per cent carbon residue 0.13, neutralization number 0.02.

The comparative results obtained appear in the following table:

Bearing Neut. munber Increase in Naphtba Carbon Gmvlty- 2 ,3??? insolubles residue Per cent Per cent Per cent 1.24 26.7 7 8 24s 0.20 1.81 Nil 29.0 3 l 8. 7 1.05 Nil 24.2 0 7 2.2 0.24 0. 52 0.40 27. 3 A 13 0.85 1.55

of oil lines, etc., in the engine is also a factor, it

- supported in a chamber in which air is present,

and streams of the oil under test are continuously directed, under per sq. inch pressure onto the sanded surfaces of bearing and strip for a period of 15 hours. The oil is maintained at a temperature of 325 F. Means are provided for recirculating the oil so that a .given quantity is used for a given test, thus simulating service conditions in an engine. The copper strip furnishes a reproducible and controlled source of catalyst. The apparatus described is the Underwood oxidation testing apparatus, supplied by the Scientific Instrument Company of Detroit, Michigan, and the test is carried out in this apparatus in accordance with General Motors specifications.

The following results, obtained by utilization of the foregoing test for comparativeevaluation of motor oils with and without the added inhibitors of this invention, clearly evidence the effectiveness of the inhibitors in preventing bearing corrosion as well as deterioration of the oil. The oil used was a motor oil of S. A. E. rating comprising a blend of solvent refined Pennsylvania neutral oil with a conventionally produced bright stock. The oil had an A. P. I. gravity of 30.0; a viscosity at 210 F. of 54 Saybolt seconds, and 294 seconds at 100 F.; carbon residue of'0.40%, naphtha insolubles, nil; neutralization number 0.02; flash point 445 F.; fire point 495 F.; pour point to 20 F.; color 5. Before each run the test apparatus was carefully cleaned with solvents to remove the deposited material from the previous run and the bearing and copper strip were each freshly sanded and weighed.

The results appear in the following table:

0 The above tests amply illustrate the effective- 15 ness of the inhibitors of this invention in preventing bearing corrosion and deterioration of the oil.

The loss in weight of the cadmium-silver bearing used in the Underwood test is a measure of 20 the amount of corrosive products present or developed in the oil being tested. Losses in weights of cadmium-nickel, copper-lead and the like bearings would be less under the same test conditions because the cadmium-silver alloy used is 25 more susceptible to corrosion than the latter named'bearing metal alloys,

Neutralization number, although not a direct measure of corrosive properties, is an indication of the change taking place in the oil during test and represents roughly the acidity of the oil.

40 hereinabove in detail in its application to motor lubricating oils,-it should not be considered as limited to that field. For example, straight cutting oils, 1. e. oils used for heavy cutting operations on metals (as distinguished from soluble" cutting oils), may be thus inhibited against deterioration in service. This type of oil is usually composed of a blend of a mineral lubricating oil and sulfurized vegetable oil such as sulfurized wood fatty acids. These oils are adapted to provide lubrication under extreme pressure conditions such as is often encountered in modern machine shop practice; but the oils heretofore used tend to oxidize and polymerize to form gummy and resinous materials under the conditions prevailing in use, thus decreasing their effectiveness for the intended purpose and shortening the useful service life of the oil.

According to this invention such cutting oils Table I 1 Bearing Neut. number Increase in i b.- aphtha Carbon 011 used lgorss in Gravity mg. Kgillilll gm. iszlizs itry insolubes residue Per cent Per cent Per cent S. A. E. 20 (uninhibite .07 24.0 9. 6 44 0. 49 3.00 S. A. E. 20 plus 0.5% of sodium dioctyl suite-succinct .01 29. 5 0.8 4 0.13 0. 90 S. A. E. 20 plus 0.5% of calcium dioctyl sulfo-succinate .01 29. 8 0. 4 6 0. 04 0. 89 S A. E. 20 plus 0.5% of aluminum dioctyl sulfo succmete. Nil 29. 9 0. 4 Nil 0. l6 0. 62

Further similar tests were made in the Underwood apparatus using a Pennsylvania base motor oil of S. A. E. 10 rating consisting of a blend of 96% of solvent refined neutral oil and 4% bright stock having the following characteristics: gravity 31.5, flash point 410 F., fire point 465 F., pour point below minus 10 F., viscosity 210 F.

can be satisfactorily stabilized against deterioration in service by incorporating therein one or more of the inhibitors described above. Upon heating a cutting oil comprising about refined mineral oil and about 10% sulfurized wood fatty acid base in metal container for 70 hours 76 in an oven maintained between 220 and 230 F.

there resulted a large amount 01' hard adherent resin-like deposit upon the surface of the metal container. When a fresh supp of the same cutting oil in which had been incorporated 1% 01' sodium dioctyl suiio-succinate was heated under identical conditions no resinous or gummy deposit was formed on the metal container and only a small amount of such deposit had occurred after 400 hours of heating. This accelerated test clearly shows the efiectiveness of the addition agents to this invention.

Summarizing, the invention comprises mineral oils having incorporated therein salts of esters of sulpho carboxylic acids in amounts efi'ective to inhibit deterioration of the oil in service, and is particularly concerned with providing viscous mineral lubricating oil of motor' grades containing such amounts of said compounds as to be inhibited against deterioration and corrosive attack upon cadmium-silver, cadmiumnickel and copper-lead and like alloy bearings, and deposition of varnish and like material in service. The invention also naturally includes the method of lubricating engines and the like comprising utilization of such inhibited 0115 as the lubricating medium.

I claim:

l. A substantially non-aqueous mineral oil composition not normally susceptible to emulsiflcation in its intended uses comprising a hydrocarbon oil normally tending to deteriorate in service and a salt of an ester of a sulfo carboxylic acid dissolved in said oil in deterioration inhibiting proportions.

2. A substantially non-aqueous mineral oil composition not normally susceptible to emulsiflcation in its intended'uses comprising a hydrocarbon oil normally tending to deteriorate in service and a salt of an ester of a sulfo dicarboxylic acid dissolved in said oil in deterioration inhibiting proportions.

3. A substantially non-aqueous mineral oil composition not normally susceptible to emulsification in its intended uses comprising a hydrocarbon oil normally tending to deteriorate in service and a salt of a dialkyl ester of a sulfo dicarboxylic acid incorporated in said oil in deterioration inhibiting proportions.

4. A substantially non-aqueous lubricant not normally susceptible to emulsification in its intended uses and useful in the lubrication of internal combustion engines comprising a hydrocarbon lubricating oil.of motor oil character normally tending in service to corrode alloys of the type having substantially the corrosion susceptibility of cadmium-silver, cadmium-nickel and copper-lead alloys and a salt of an ester of a sulfo carboxylic acid incorporated with said oil in corrosion inhibiting proportions.

5. A substantially non-aqueous lubricant not normally susceptible to emulsification in its intended uses and useful in the lubrication of internal combustion engines comprising a hydrocarbon lubricating oil of motor oil character normally tending, in service, to deteriorate and having substantially the corrosion susceptibility of cadmium-silver. cadmium-nickel and copperlead alloys, and a salt of a dialkyl ester of suli'o succinic acid in proportions effective to inhibit said oil deterioration and alloy corrosion.

6. A substantially non-aqueous lubricant not normally susceptible to emulsification in its intended uses comprising a hydrocarbon 011 normally tending to deteriorate in service and a salt of an ester of a sulfo dicarboxylic acid in proporassaoarf tions eflective to inhibit or retard deterioratir of said 011, said salt containing at least one resil ual alcohol radical or from about 5 to about 1 carbon atoms. I

7. A substantially non-aqueous mineral o composition not normally susceptible to emuls flcation in its intended uses comprising a hydrr carbon oil normally tending to deteriorate 1 service having incorporated therewith deteriorl tion inhibiting proportions of an alkaline cart salt of an. ester of a sulfo dicarboxylic acid.

8. A substantially non-aqueous mineral o composition not normally susceptible to emulsi ilcation in its intended uses comprising a refine hydrocarbon oil normally tending to deteriorat in service having dissolved in said 011 deteriora tlon inhibiting proportions of a dialkyl succinat calcium sulionate. n V

9. A substantially non-aqueous mineral o1 composition not normally susceptible to emulsi flcation in its intended uses comprising hydro carbon oil normally tending to deteriorate 11 service having dissolved therein deterioration in hibiting proportions of dioctyl succinate cal cium sulfonate. y 10. A substantially non-aqueous mineral oi composition not normally susceptible to emulsiflcation in its intended uses and suitable for us as a cutting oil having extreme pressure characteristics comprising a hydrocarbon oil and a salt of an ester of a sulfo carboxylic acid.

11. A substantially non-aqueous mineral oi composition not normally susceptible to emulsiflcation in its intended uses and suitable for use as a cutting oil having extreme pressure characteristics comprising hydrocarbon oil, sulfurized vegetable oil and deterioration inhibiting proportions of a salt of an ester of a sulfo dicarboxylic acid.

12. A substantially non-aqueous mineral oil composition not normally susceptible to emulsiflcation in its intended uses comprising hydrocarbon oil normally tending to deteriorate in service having dissolved therein deterioration inhibiting proportions of a salt of an ester of a sulfo dicarboxylic acid having branched chain structure.

13. A substantially non-aqueous mineral oil composition not normally susceptible to emulsiflcation in its intended uses comprising hydrocarbon oil normally tending to deteriorate in service having dissolved therein deterioration inhibiting proportions of a salt of an ester of a sulfo dicarboxylic acid having at least one residual alcohol radical of branched chain structure.

14. A substantially non-a ueous lubricant not normally susceptible to emu ification in its intended uses and useful in the lubrication 01' internal combustion engines comprising a hydrocarbon lubricating oil of motor oil character normally tending in service to deteriorate and cause deposition of solid material in-the engine, and a salt of a dialkyl ester of a sulfo dicarboxylic acid, said salt having branched chain structure.

15. A substantially non-aqueous mineral oil composition not normally susceptible to emulsification in its intended use comprising a hydrocarbon oil normally tending to deteriorate in service having incorporated therein deterioration inhibiting proportions of a salt of an ester of a sulfo carboxylic acid, said salt containing radicals tending to increase its solubility in said oil and being free from free acid radicals.

16. An improved lubricating composition comprising a mineral oil and dissolved therein a small amount of an oil-soluble salt of calcium with an ester of a sulpho dicarboxylic acid of the general formula COOX wherein R is an aliphatic radical containing at least one sulphonic group and X and X1 are alcohol radicals containing at least five carbon atoms.

17. A compounded mineral lubricating oil containing a small amount of a calcium salt of a sulphonic acid dioctyl succinic ester.

18. A mineral oil composition comprising a hydrocarbon oil normally tending to cause ringsticklng and hearing corrosion in service, and a small amount of an oil-soluble salt of an ester of a sulfo carboxylic acid efl'ective to inhibit such ring-sticking and bearing corrosion.

19. A mineral oil composition comprising a hydrocarbon oil normally tending to cause ringsticking and bearing corrosion in service, and a small amount of an oil-soluble salt of an ester of a sulfo dicarboxylic acid effective to inhibit such ring-sticking and bearing corrosion.

20. A mineral oil composition comprising a hydrocarbon oil normally tending to cause ringsticking and bearing corrosion in service, and a small amount of an oil-soluble salt of a polyvalent metal with an ester of a. sulfo carboxylic acid efl'ective to inhibit such ring-sticking and bearing corrosion.

21. A mineral oil composition comprising a hydrocarbon oil normally tending to cause ringsticking and bearing corrosion in service, and a small amount of an oil-soluble aluminum salt of an ester of a sulfo carboxylic acid eilective to inhibit such ring-sticking and bearing corrosion.

STANLEY P. WAUGH.