US3859221A

US3859221A - Lubricant compositions exhibiting synergistic relief of metal fatigue

Info

Publication number: US3859221A
Application number: US353179A
Authority: US
Inventors: Conrad J Polk
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1973-04-20
Filing date: 1973-04-20
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07

Abstract

Lubricant compositions are provided containing, in an amount sufficient to improve metal-fatigue, a synergistic mixture of (a) isopropylaminoethanol and (b) a reaction product of an alkenyl succinic anhydride and a polyethylene amine.

Description

United States Patent [1 1 Polk [111 3,859,221 1 1 Jan. 7, 1975 1 1 LUBRICANT COMPOSITIONS EXHIBITING SYNERGISTlC RELIEF OF METAL FATIGUE [75] Inventor: Conrad J. Polk, Cranbury, NJ.

173] Assignee: Mobil Oil Corporation, New York,

[21] Appl. No.: 353,179

[521 US. Cl. 252/515 A, 252/515 R [51] Int. Cl Cl0m 1/32 [58] Field of Search 252/515 A, 51.5 R

[56] References Cited UNITED STATES PATENTS 3,219,666 11/1965 Norman et a1 252/515 A X 3,280,029 10/1966 Waldman ..252/49.5

Primary ExaminerDaniel E. Wyman Assistant ExaminerAndrew H. Metz Attorney, Agent, or Firm-Andrew L. Gaboriault; Raymond W. Barclay; Benjamin 1. Kaufman 571 1 ABSTRACT 10 Claims, No Drawings LUBRICANT COMPOSITIONS EXHIBITING SYNERGISTIC RELIEF OF METAL FATIGUE BACKGROUND OF THE INVENTION metal-fatigue, which, essentially, involves metal deterioration due to the application of cyclic stresses in undergoing use, as, for example, in rolling contact bearings. In order to induce anti-fatigue properties to the lubricating medium, and particularly where the lubricant is, to some extent, water-contaminated, various additives have heretofore been suggested as antifatigue agents. Such additives have not, however, been found sufficiently successful to justify extensive commercial use as lubricant additives.

SUMMARY OF THE INVENTION It has now been found that highly superior antifatigue properties can be exhibited by lubricant compositions, by incorporating therein minor amounts of a synergistic mixture of (a) isopropylaminoethanol and (b) a reaction product of an alkenyl succinic anhydride and a polyethylene amine.

Insofar as the lubricant medium, per se, is concerned, this may comprise any liquid hydrocarbon oil, in the form of either a mineral oil or a synthetic oil, or in the form of a grease in which any of the aforementioned oils are employed as a vehicle. In general, mineral oils, employed as the lubricant, or grease vehicle, may be of any suitable lubricating viscosity range, as, for example, from about 45 SSU at 100F. to about 6,000 SSU at 100F., and, preferably, from about 50 to about 250 SSU at 210F. These oils may have viscosity indexes varying from below zero to about 100 or higher. Viscosity indexes from about 70 to about 95 are preferred. T he average molecular weights of these oils may range from about 250 to about 800. Where the lubricant is to be employed in the form of a grease, the lubricating oil is generally employed in an amount sufficient to balance the total grease composition, after accounting for the desired quantity of the thickening agent, and other additive components to be included in the grease formulation.

In instances where synthetic oils, or synthetic oils employed as the vehicle for the grease, are desired in preference to mineral oils, or in combination therewith, various compounds of this type may be successfully utilized. Typical synthetic vehicles include polyisobutylene, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, di(2-ethy1 hexyl) sebacate, di(2-ethyl hexyl)adipate, di(butyl phthalate, fluorocarbons, silicate esters, silanes, esters of phosphorous-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chain-type polyphenyls, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl ethers typified by a butylsubstituted bis (p-phenoxy phenyl) ether, phenoxy phenylethers, etc.

Of particular importance, for the purpose of improving metal fatigue, is the synergistic mixture of (a) isopropylaminoethanol and (b) a reaction product of an alkenyl succinic anhydride and a polyethylene amine. As hereinafter described, even though component (a) and component (b) individually, are found to impart improved fatigue lifeto metal, the combination of these two components, in a total amount no greater than that employed individually for each component, exhibits a synergistic effect, by imparting a markedly increased benefit as far as anti-fatigue effect is concerned, greater than that of the aforementioned components, individually, even though the total weight of the combination does not exceed that of components (a) and (b), individually.

Insofaras the isopropylaminoethanol (a) and the aforementioned reaction product (b) are concerned, these two components are found to be synergistic in all proportions. For most applications components (a) and (b) are generally employed in a mol ratio from about 1:4 to about 4:1. Insofar as component (b) is concerned, the alkenyl succinic anhydride'and the polyethylene amine are generally reacted in a mol ratio of about 2: 1'. In general, the synergistic mixture of component (a) and (b) may be incorporated in the lubricant in any amount sufficient to improve metal fatigue. For most applications the synergistic mixture is employed in an amount from about .01 to about 10% and, preferably, in an amount from about 0.1 to about 2%, by weight, of the total weight of the lubricant composition.

Insofar as the components of the synergistic mixture are concerned, isopropylaminoethanol, i.e., component (a), is a known compoundand is described in the literature, together with its method of preparation, for example, in U.S. Pat. No. 3,280,029. The aforementioned reaction product, i.e., component (b), is also known and'described in'the literature, together with its method of preparation, for example, in U.S. Pat. Nos. 3,172,892 and 3,219,666.

DESCRIPTION OF SPECIFIC EMBODIMENTS In order to demonstrate the improvement in metal antifatigue properties realized by employing the abovedescribed novel synergistic mixture of the present in'- vention, compared with that realized by employing components (a) and (b), individually, comparative data were obtained as shown in the examplesof the following table. Insofar as theindividual components of the synergistic mixture are concerned, the isopropylaminoethanol was prepared in accordance with the procedure described in'the aforementioned U.S. Pat. No. 3,280,029; component (b) was prepared in accordance with the procedure described in the aforementioned U.S. Pat. Nos. 3,172,892 and 3,219,666, in which 0.5 mol of each of components (a) and (b), making a total of 1 mol synergistic mixture, was employed. Insofar as component (b), employed in the following comparative data, is concerned, this product was obtained by reacting 0.5 molof polyisobutenyl succinic anhydride and 0.25 mol of tetraethylenepentamine at a temperature of C. until the evolution of water had ceased.

The data were obtained by means of the General Electric Rolling Contact Fatigue tester. This equipment is widely accepted, in the art, as a rolling contact fatigue tester. Data are obtained by loading two crowned discs against a cylindrical test specimen with the discs and specimen rotating at 12,500 rpm. The end of the test occurs when one or more pieces of metal break away from the specimen surface as a result of metal fatigue. The formation of such pits on the specimen surface results in vibration of the apparatus which is sensed by a vibration switch incorporated in the instrument. The test is terminated when the vibration level exhibits a preset level set on the vibration sensor.

In the above test, at least six fatigue failures were obtained for each lubricant formulation. The data were analyzed by Maximum Likelihood statistics to give the L life, L life, and Weibull slope of the population. L life is defined to be that life (in stress cycles) which 90% of the test specimens are expected to survive; L life is defined to be that life which 50% of the test specimens are expected to survive. The Weibull slope is a statistical parameter which measures the degree of spread of the data in a given population. In fatigue testing, improvements in specimen life are determined by increased values of the L and L life of a population relative to a reference fluid; thus in the data presented herein, improved performance affected by the additives individually or in combination, is reflected by increased and L life values. With the above test standards in view, the following data, as shown in the table, were obtained employing the above-described equipment and employing identical test procedures under identical test conditions in each instance. Each test was conducted with M-50 steel discs and SAE 52100 steel test specimens (-63 Rockwell C hardness) at a test speed of 12,500 rpm and a Hertz load of 700,000 psi.

TABLE ence to preferred compositions and components therefore, it will be understood, by those skilled in the art, that departure from the preferred embodiments can be effectively made and are within the scope of the specification.

1 claim:

1. A lubricant composition comprising a major proportion of a liquid hydrocarbon oil selected from the group consisting of mineral oils, synthetic oils and greases thereof, containing, in an amount sufficient to improve metal fatigue, a synergistic mixture of (a) isopropylaminoethanol and b an alkenyl succinimide of an alkenyl succinic anhydride and a polyethylene amine, in a mol ratio of about 2:1 and in a mol ratio of (a) to (b) from about 1:4 to about 4:1.

2. A lubricant composition as defined in claim 1 wherein said composition comprises a mineral oil of lubricating viscosity in the range from about SSU at 100F. to about 6,000 SSU at 100F.

3. A lubricant composition as defined in claim 1 wherein said composition comprises a mineral oil of lubricating viscosity in the range from about SSU at 210F. to about 250 SSU at 210F.

4. A lubricant composition as defined in claim 1 wherein said synergistic mixture is present in an amount from about 0.01 to about 10%, by weight, of the total weight of the lubricant composition.

5. A lubricant composition as defined in claim 1 wherein said synergistic mixture is present in an amount from about 0.1 to about 2%, by weight, of the total weight of the lubricant composition.

6. A lubricant composition asdefined in claim 1 wherein said alkenyl succinic anhydride is polyisobutenyl succinic anhydride.

G. E. Rolling Contact Fatigue Test Data* L Life L,,, Life L,, Test Oil (L...) Test on Total Example Lubricant Formulation (Cycles X 10) (Cycles X 10) (L,,,) Wet Oil (L Wet Oil Percent l SAE 20 mineral oil 3.46 7.20 100% 100% 200% water 2 SAE 20 mineral oil 5.47 7.05 158% 98% 256% water isopropy- .aminoethanol (lmol 1 3 SAE 20 mineral oil 4.70 9.82 136% 136% 272% +water "reaction product (1 mol 4 SAE 20 mineral oil 5.10 11.84 147% 164% 311% water isopropylaminoethanol (0.5 mol and reaction product (0.5 mol SAE 52100 steel specimens 12,500 rpm 700,000 psi nominal Hertz Stress "Reaction product of polyisobutenyl succinic anhydride and tetraethylenepentamine As will be apparent from the foregoing table, the total improvement in fatigue life of the treated oil over the base oil was 56%, as shown in Example 2, where 0.5 mol of isopropylaminoethanol was individually employed (200% of Example 1 versus 256% of Example 2). Where the test oil contained 0.5 mol of the above-described polyisobutenyl succinic anhydridetetraethylenepentamine reaction product, an improvement of 72% was obtained (Example 3). However, where the test oil contained 0.5 mol of isopropylaminoethanol and 0.5 mol of the aforementioned reaction product, an improvement of 1 l 1% was obtained (Example 4), markedly indicative of a true synergistic effect.

While this invention has been described with refermine.

Claims

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF A LIQUID HYDROCARBON OIL SELECTED FROM THE GROUP CONSISTING OF MINERAL OILS, SYNTHETIC OILS AND GREASES THEREOF, CONTAINING, IN AN AMOUNT SUFFICIENT TO IMPROVE METAL FATIGUE, A SYNERGISTIC MIXTURE OF (A) ISOPROPYLAMINOETHANOL AND B AN ALKENYL SUCCINIME OF AN ALKENYL SUCCINIC ANHYDRIDE AND A POLYETHYLENE AMINE, IN A MOL RATIO OF ABOUT 2:1 AND IN A MOL RATIO OF (A) TO (B) FROM ABOUT 1:4 TO ABOUT 4:1.

2. A lubricant composition as defined in claim 1 wherein said composition comprises a mineral oil of lubricating viscosity in the range from about 45 SSU at 100*F. to about 6,000 SSU at 100*F.

3. A lubricant composition as defined in claim 1 wherein said composition comprises a mineral oil of lubricating viscosity in the range from about 50 SSU at 210*F. to about 250 SSU at 210* F.

6. A lubricant composition as defined in claim 1 wherein said alkenyl succinic anhydride is polyisobutenyl succinic anhydride.

7. A lubricant composition as defined in claim 1 wherein said polyethylene amine is tetraethylenepentamine.

8. A synergistic mixture of (a) isopropylaminoethanol and (b) an alkenyl succinimide of an alkenyl succinic anhydride and a polyethylene amine, in a mol ratio of about 2:1 and in a mol ratio of (a) to (b) from about 1:4 to about 4:1.

9. A synergistic mixture as defined in claim 8 wherein said alkenyl succinic anhydride is polyisobutenyl succinic anhydride.

10. A synergistic mixture as defined in claim 8 wherein said polyethylene amine is tetraethylenepentamine.