US2991249A - Grease composition containing an imidazoline - Google Patents

Description

Patented July 4, 1961 2,991,249 GREASE COMPOSITION CONTAINING AN IMIDAZOLINE Harry J. Andress, Jr., Pitman, N.J., and Richard A. Butcosk, East Hempstead, N.Y., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Jan. 12, 1960, Ser. No. 1,844

16 Claims. 252- 40) This invention relates to lubricating grease compositions suitable for use over a wide range of operating conditions. More specifically, the present invention is concerned with greases of excellent flow characteristics and a high degree of resistance to deterioration when in contact with water.

This application is a continuation-in-part of application Serial No. 683,681, filed September 13, 1957, and now abandoned.

There has been an increasing need for greases of outstanding lubricating character which can be used under a variety of conditions prevailing in modern industrial equipment. For example, it is necessary that a grease should flow at low temperatures, of the order of 40 F., without making necessary the use of high pressure equipment to deliver it to the system to be lubricated. This is illustrated by the problem encountered in service stations during winter months in the northern areas of this country. Grease dispensing guns operate at pressures of the order of 50-100 p.s.i.; yet, when prevailing temperatures are lower than about 50 R, such guns are inadequate in delivering automotive greases to an automobile chassis.

The flow character of a grease is generally designated in the art by the term feedability. This is the ability of a lubricating grease to flow to the suction of a dispensing pump at a rate at least equal to pump delivery capacity. Some lubricating greases do not feed satisfactorily and cause cavitation at the inlet to a dispensing pump.

Another prime demand is for a grease resistant to the action of water. That is, the action of water-Whether salt or fresh water-may cause the grease to thin out into a liquid which leaks from lubricated surfaces. This is a major consideration inasmuch as grease-lubricated machine parts are encountered in port installations, on deck of navy and marine vessels, in steel rolling mills, in water pumps of all kinds, in mining machinery, in oil-well drilling equipment, etc. In many of such instances, relatively high operating temperatures develop, such that even lime base greases, which are highly resistant to water, become unstable. While a number of modifying agents have been incorporated in various grease types to improve their stability, such modifying agents generally have depreciated one or more other desirable characteristics.

In the same connection, many of the past and present day greases have failed to provide resistance to corrosion in humid air of the machine parts which the greases should protect. Such greases have been excessively hygroscopic in character, and in this respect have not been desirable for applications where they come in contact with the surface to be protected.

It has now been found that greases characterized by excellent feedability, water resistance and corrosion redefined above as coming within this invention, and reaction products closely related to those of this invention, do not have the desired properties. These surprising findings are revealed below by typical test data.

Accordingly, it is a primary object of this invention to provide a grease characterized by improved feedability, particularly at low temperatures.

It is a further object of the invention to provide a grease having excellent water absorption characteristics (or resistance to deterioration when in contact with water).

Another object is to provide a grease giving outstanding resistance to rusting of metal surfaces in the presence of water, when applied to such surfaces.

Additional objects will be apparent from the following description of the invention.

As indicated above, the soaps present in the greases of this invention have as metal components lithium, calcium or combinations of the two metals. The acid components are monocarboxylic acids having from about fourteen to about twenty-two carbon atoms per molecule. Typical of such acids are myristic, palmitic, oleic, stearic, hydroxy-stearic, arachidic and behenic. Fatty materials containing such acids are also contemplated herein. The fatty materials can be vegetable, marine and animal fatty oils, and hydrogenated products thereof, so long as the acids therein are primarily within the definition mentioned above. Stearin, tallow, cottonseed oil acids, hydrogenated castor oil, hydrogenated fish oils such as Hydrofol, are typical. Preferred herein, however, are the following soaps: calcium stearate, lithium stearate and mixtures of lithium and calcium soaps of C -C acids.

Methods for preparing lithium, calcium and lithiumcalcium soaps are well known in the art and discussion of the same is believed to be unnecessary. However, several illustrative examples of such methods are provided hereinafter.

The quantity of soap or soaps present in the new greases range from about 5 to about 30 percent by weight, preferably from about 7 to about 15 percent.

As already indicated, the reaction products present in the new greases are obtained by reacting a naphthenic acid with an ethylenepolyamine. The latter is repre sented by the general formula wherein R is hydrogen or an aliphatic group preferably an aliphatic group having from about 8 to about 18 carbon atoms; and n is an integer of at least 2, preferably from 2 to 4, there being no upper limit to the number of ethylene-imino groups (C H NH) present in the molecule.

Typical ethylene polyamines are: diethylene triamine, triethylene tetramine, tetraethylene pentamine and pentaethylene hexamine, N-dodecyl diethylene triamine; N-keryl diethylene triamine (wherein the keryl group R is derived from kerosine and is a mixture of C to C with a major portion of C Of such amines, it has been found that diethylene triamine is particularly advantageous herein and represents a preferred reactant.

Reacted with the polyarnines described above are naphthenic acids which are monocarboxylic acids obtained from crude petroleum or from distillates thereof. Such acids are Well known in the art, having been well described in the Encyclopedia of Chemical Technology, edited by R. F. Kirk et al.; The Interscience Encyclopedia, Inc., New York, 1952, volume 9, pages 241 -247; and by Carleton Ellis in The Chemistry of Petroleum Deriv-i atives, The Chemical Catalog Co., Inc.; New York, 1934; chapter 48, While all such acids can be used herein, it

is preferred that the naphthenic acids have an acid number from about 120 to about 240. Such acids have average molecular weights from about 290 to about 420, and an average of 7 to about 30 carbon atoms per molecule. Excellent results have been obtained with a naphthenic acid having an acid number of about 200, an average molecular weight of 275-300, and a major proportion thereof having from to carbon atoms per molecule. Naphthenic acids available commercially to date are mixtures rather than individual compounds.

The reaction products are prepared by reaction of from about 2 to about 4 molar proportions of a naphthenic acid with one molar proportion of an ethylene polyamine of the character described above wherein R is hydrogen or is an aliphatic group having less than about 7 carbon atoms; a preferred ratio is 2:1. contemplated herein also are reaction products obtained by reaction of from about 1 to about 2 molar proportions of a naphthenic acid With one molar proportion of the amine, wherein R has at least about 8 carbon atoms; the preferred ratio for preparing such products is 1:1.

When the ethylene polyamine used is diethylene triamine, for example, and two molar proportions of a naphthenic acid are reacted with one molar proportion of said amine, the reaction product so obtained, most probably, is predominantly comprised of one or more imidazolines represented by the general formula:

wherein R is naphthenyl.

It is to be understood that since available naphthenic acids are mixtures, since some of the amines are mixtures, and since the molar ratios of the acid and amine are subject to some variation, the products are better described as reaction products than as individual compounds.

The reaction products contemplated herein are used with the new greases in concentrations of at least about 1 and not more than about 3 percent by weight, preferably between about 1 and about 2 percent.

The following specific examples of the reaction products contemplated herein and of other related reaction products, are set forth as illustrations. In such examples, the reaction products formed from naphthenic acids, with proper proportions, typify the invention. Further details on the reaction products are provided in application Serial No. 735,680, filed May 16, 1958, of Harry J. Andress, Jr.

EXAMPLE 1 A mixture of 1.76 mols (500 parts) of naphthenic acid having an acid number of 198, and 0.88 mol (91 parts) of diethylene triamine was refluxed in xylene solution for 4 hours. The reaction mixture was then slowly heated to 275 C. and was held at this temperature until the evolution of water ceased (about 2 hours). Xylene was also removed along with the water. About 2.6 mols (47 parts) of water were collected. The reaction product is predominantly comprised of 1-naphthenamidoethyl-2- naphthenyl imidazolines, corresponding to wherein R is naphthenyl.

EXAMPLE 2 In this example, the procedure was the same as in Example 1. However, the molar ratio of naphthenic acid to diethylene triamine was about 1:1 instead of 2:1. Two hundred parts of acid were used with 72.8 parts of amine. The naphthenic acid was the same as that used in Example 1. Two mols of water (36 parts) of water were collected. The product is predominantly comprised of 1-aminoethyl-2-naphthenyl imidazolines, corresponding to HgG-CH1 N N-CHzGH NH wherein R is naphthenyl.

EXAMPLE 3 wherein R is naphthenyl.

EXAMPLE 4 A mixture of 1.09 mols (300 parts) of naphthenic acid (acid number, 203) and 0.545 mol (103 parts) of tetraethylene pentamine was refluxed in xylene solutionfor 4 hours. The reaction mixture was then slowly heated to 275 C. and was held at this temperature until water was no longer evolved (about 2 hours). About 1.7 mols (31 parts) of water were collected. The reaction product is primarily composed of l-naphthenamidotriethylenediimino 2 naphthenyl imidazolines represented as wherein R is naphthenyl.

EXAMPLE 5 A mixture of one mol (282 parts) of oleic acid and 0.5 mol (51.5 parts) of diethylene triamine were refluxed in xylene solution for 4 hours. The reaction mixture was then slowly heated to 275 C. and was held at this temperature until the evolution of water ceased. The reaction product is primarily 1-octadecenylamidoethyl-Z- octadecenyl imidazoline, represented as wherein R is octadecenyl.

Illustrative of the greases contemplated herein are those shown below in Examples 6 through 10. By way of comparison, other greases are shown in Examples 11 through 15.

EXAMPLE 6 This involves the preparation of a lithium soap grease containing a minor amount of a calcium soap. The grease was prepared from the following materials:

a This is a mixture of mono and diheptyl diphenylamiues.

The lithium-calcium soap grease, without the reaction product of Example 1, was prepared by the following technique.

All of the acids, lithium hydroxide, lime flour were charged with about one-third of the oil, to a grease kettle. The charge was agitated and heated to a temperature of approximately 400 F. during a period of two hours. Heating was then discontinued. The balance of the mineral oil (at about 80 F.) was added to the kettle. The resulting product was cooled to about 200 F., over a period of about two hours. The oxidation inhibitor was added. The product was cooled to 160 F. and filled in containers.

A portion of the grease was heated on a steam table at 290300 F. The reaction product of Example 1 was added to the grease in an amount of one percent by weight, and was worked into the grease at 300 F. by means of a spatula. The resulting product was then removed to a glass table top and worked with a spatula to cool the product and further blend the reaction product and the grease. The resulting grease was then considered homogeneous and ready for testing.

EXAMPLE 7 A lithium-calcium soap grease prepared as in Example 6, but without the reaction product of Example 1 incorporated therein, was used. The grease was heated on a steam table and the reaction product of Example 1 was added as described in Example 6. Various quantities of the same reaction product, ranging from 0.5 to percent by weight, were added to the grease to provide compositions for evaluation.

EXAMPLE 8 A lithium stearate grease of the following composition was used:

Weight percent Hydrogenated soya fatty acids 13.00

Lithium hydroxide monohydrate 1.92

Oxidation inhibitor 0.60

Mineral oil, 100 secs, S.U.S. 100 F 84.48

The lithium stearate grease was prepared by the same procedure as described in Example 6. It is tobe noted that calcium is not present in this grease.

One percent by weight of the reaction product of Example 1 was incorporated in the lithium stearate grease, following the procedure described in Example 7.

EXAMPLE 9 A commercial calcium tallow grease of cup grease nature was used. Such a grease is described by Klemgard in Lubricating Greases: Their Manufacture and Use, New York, Reinhold Publishing Corp., 1937.

One percent by weight of the reaction product of Example 1 was incorporated in the grease, by the procedure described in Example 7.

EXAMPLE 10 A grease containing lithium 12-hydroxy stearate and lithium soaps was used. This has the following composition:

Weight percent Stearic acid 1.82 12-hydroxy stearic acid 7.28 Lithium hydroxide monohydrate 1.30 Oxidation inhibitor 0.75 Mineral oil, 500 secs, S.U.S. F 88.85

It was prepared by the procedure described in Example 6.

One percent by weight of the reaction product of Example 1 was incorporated into the grease, by the procedure given in Example 7.

EXAMPLE 11 A grease containing lithium stearate and sodium stearate was used. This has the composition:

Weight percent Stearic acid 10.90 Lithium hydroxide monohydrate 1.51 Caustic soda 0.29 Oxidation inhibitor 0.59 Mineral oil, 750 secs., S.U.S 100 F 86.71

EXAMPLE 12 A sodium stearate-sodium oleate grease of the following composition was used:

Weight percent Oleic acid 7.15 Stearic acid 7.15 Glycerine 1.70 Caustic soda 2.50 Mineral oil, 300 secs, S.U.S. 100 F 81.50

The acids, glycerine, caustic soda and about one-third of the mineral oil, where heated and agitated in a grease kettle to about 300 F. during a period of about 2 hours. About one-half of the balance of the mineral oil was added slowly. Heating was discontinued. The remainder of the mineral oil was added slowly as the mixture cooled to 200 F. The resulting grease was then packaged.

Following the procedure of Example 7, one percent by weight of the reaction product of Example 1 was incorporated into the grease.

EXAMPLE 13 The lithium-calcium grease, not containing an acidamine reaction product, as identified in Example 7, was used. To this was added one percent by weight of the reaction product of Example 2.

EXAMPLE 14 The lithium-calcium grease used in Example 13 was used with one percent by weight of the reaction product of Example 5. The blend was made by the procedure described in Example 7.

EXAMPLE 15 The lithium-calcium grease used in Example 13 was used with one percent by weight of a petroleum sulfonate. The latter was a sodium salt having an average molecular weight of about 300. The grease and sulfonate were blended by the procedure described in Example 7.

Several tests were conducted on the compositions'described above to determine their character.

Feedability was determined by the following procedure. Forty pounds of grease to be tested was charged to a grease drum. The drum was cooled to a temperature of 37-38 F. A grease pump, also cooled to this temperature, was placed in the drum. The inlet side of the pump was immersed in the grease. The pump was a Lincoln Airline Lubrigun, Model Number 8 1694; this was operated at 90 p.s.i. The grease was discharged from the pump through seven feet of flexible hose A inch inside diameter) a Lincoln control valve and a restn'ctor consisting of twelve inches of copper tubing A inch inside diameter), into a container. The grease was pumped continuously until grease flow ceased due to cavitation at the pump inlet. The total amount of grease pumped prior to cavitation was weighed. The weight of grease so pumped relative to the amount available to the inlet ports of the pump, expressed as percent of grease pumped, is taken as a measure of feedability of the grease under test. A higher value indicates better feedability.

A lithium-calcium soap grease similar to that described in Example 6, but containing 6 percent of soap instead of 9.5 percent, was subjected to this test. This did not contain a reaction product of naphthenic acid and an ethylene polyamine. Approximately 17.5 percent of the grease charge was pumped from the drum before cavitation occurred. In contrast, another lithium-calcium soap grease corresponding to that of Example 6 but containing 7 percent of soap and containing one percent of the reaction product of Example 1, was far superior in feedability. Sixty-one percent of this grease Was so removed before cavitation. This difference, sixty-one percent as opposed to seventeen and one-half percent, is even more marked in view of the different soap contents of the greases tested. A grease of lower soap content would be expected to have better feedability characteristics than a grease or corresponding composition but of higher soap content.

Water resistance.

This test involves using twenty grams of a grease in a three inch diameter cup; distilled water is added to the grease in increments of one cubic centimeter (five percent); and the grease is then Worked with a smooth pedestal at a speed of about 1700 rpm. for a period of l-2 minutes. Additional water is then added and the pro cedure is repeated until water is visible in the grease after the working period. A value of less than 100 in this test indicates a satisfatcory grease. The test is identified as Government Specification 0.8. 1350.

Test results are shown in Table I below.

TABLE I Water Absorption (0.8. 1350),

Type of Soap Grease Percent Example No.

Li-Ca stearate do 100+Body. 100+Body. 100+B0dy. igM-Body.

o Ll 12-Hydroxy Steer ate and Li stearate.

. Li-Na Stearates Na Stearate-Oleate 100+Body. 100+N0 Body. 70 Body. 100 No Body.

40. 105 Throws Out Water.

40. 125+B0dy. 40.

The results shown in Table I reveal that the reaction product of Example 1 (naphthenic acid-diethylene triamine, 2:1 molar ratio) is effective in concentrations of 0.5 percent up to about 3 percent by weight, in a lithiumcalcium soap grease. It is also effective in: a lithium stearate grease; a calcium stearate grease; and a lithium hydroxystearate-lithium stearate grease. It is not effective in: a lithium stearate-sodium stearate grease; and a sodium stearate-sodium oleate grease. The results also show (Example 13) that the calcium-lithium soap grease having a naphthenic acid-diethylene triamine reaction product having a 1:-1 molar ratio is unsatisfactory. Correspondingly, Example 14 shows that an oleic acid reaction product fails to improve the lithium-calcium soap grease. And Example 15 reveals that a petroleum sulfonate is ineffective.

Corrosion test TABLE II Reaction Product, Percent By Wt.

CRC Cor- Type of Soap Grease rosion Test Example No.

None 1 Li 12-Hydr0xy stearate and Li stearate.

do n Li-Cda stearate The results provided in Table II indicate that the reaction product of Example 1 (naphthenic acid-diethylene triamine, 2:1 molar ratio) is effective in concentrations of about one percent by weight, in the greases shown.

It is to be understood that the greases of this invention can also contain other characterizing materials. For example, the greases can contain grease antioxidants such as amines, phenols, sulfides, etc., and lubricity improving agents such as free fat, free fatty acids, esters of alkyl and/ or aryl acids, sulfurized fats, lead soaps, molybdenum disulfide, etc. These characterizing materials do not detract from the lubricating value of the greases contemplated herein; rather, these characterizing materials serve to impart their customary properties to the grease.

The greases of this invention are suitable for a wide range of industrial application. Some, for example, are suitable for mnlti-purpose automotive greases, serving as chassis, wheel-bearing, water-pump grease lubricants. Others are multipurpose industrial greases serving as plain-bearing and anti-friction greases for normally loaded and heavily loaded equipment. In general, then, greases contemplated herein range from semi-fluid types suitable as textile machinery lubricants, to solid block type greases used in lubrication of machinery in steel mills, paper mills, cement mills, etc.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of this invention. Such variations and modifications are considered to be within the scope and purview of the appended claims.

We claim:

1. A grease composition comprising: a mineral oil of lubricating viscosity; a soap thickening agent in an amount sufiicient to thicken said mineral oil to a grease, said soap thickening agent being selected from the group consisting of a lithium soap, 'a calcium soap and mixtures of lithium and calcium soaps of an aliphatic monocarboxylic acid having from about fourteen to about twentytwo carbon atoms per molecule; and from about one to about three percent by Weight of an imidazoline selected from the group represented by the general formulae i it and mixtures thereof, wherein n is selected from the group consisting of zero and an integer of at least one, R is naphthenyl, and R is selected from the group consisting of hydrogen and an aliphatic hydrocarbon :group having up to about 18 carbon atoms.

2. A grease composition as defined by claim 1 wherein the soap thickening agent is a lithium soap.

3. A grease composition as defined by claim 1 wherein the soap thickening agent is a calcium soap.

4. A grease composition as defined by claim 1 wherein the soap thickening agent is a mixture of lithium and calcium soaps.

5. A grease composition as defined by claim 1 wherein the soap thickening agent is a mixture of lithium and calcium soaps formed from about Percent by weight 6. A grease composition as defined by claim 1 wherein the soap thickening agent is a stearate.

7. A grease composition as defined by claim 1 wherein the said imidazoline is present in an amount ranging from about one to about two percent by weight.

8. A grease composition as defined by claim 1 wherein n is 1.

9. A grease composition as defined by claim 1 wherein n is an integer from 1 to 4.

10. A grease composition as defined by claim 1 wherein R is a naphthenyl group having from 15 to 20 carbon atoms per molecule.

11. A grease composition as defined by claim 1 wherein there is present a mixture of imidazolines represented by the general formula the imidazolines difiering in the R' groups thereof, R' being naphthenyl and having from 15 to 20 carbon atoms. 12. A grease composition comprising: a mineral oil of 10 lubricating viscosity; a soap thickening agent in an amount sufiicient to thicken said mineral oil to a grease, said soap thickening agent being selected from the group consisting of a lithium soap, a calcium soap and mixtures of lithium and calcium soaps of an aliphatic monocarboxylic acid having from about fourteen to about twentytwo carbon atoms per molecule; and from about one to about three percent by weight of an imidazoline represented by the general formula wherein R is a naphthenyl group having from 15 to 20 carbon atoms; said mixture of soaps being formed from about Percent by weight Lithium hydroxide monohydrate 1.15 Lime flour 0.45 Palmitic acid 0.7 Stearic acid 8.5 Oleic acid 0.3

14. A grease composition comprising: a mineral oil of lubricating viscosity; a lithium soap in an amount sutficient to thicken said mineral oil to a grease; and from about one to about three percent by weight of the imidazoline of claim 13. p

15. A grease compisition comprising: a mineral oil of lubricating viscosity; a lithium soap of a hydroxy-substituted stearic acid, in an amount sufiicient to thicken said mineral oil to a grease; and from about one to about three percent by weight of the imidazoline of claim 13.

16. A grease composition comprising: a mineral oil of lubricating viscosity; a calcium soap in an amount sufiicient to thicken said mineral oil to a grease; and from about one to about three percent by weight of the imidazoline of claim 13.

References Cited in the file of this patent UNITED STATES PATENTS 2,243,485 Musselman May 27, 1941 2,312,082 Dietrich Feb. 23, 1943 2,336,070 Clarkson Dec. 7, 1943 2,358,581 Lieber et a1. Sept. 19, 1944 2,554,222 Stross May 22, 1951 2,622,018 White et a1. Dec. 16, 1952 2,655,476 Hughes et al. Oct. 13, 1953 2,711,393 Hughes et al. June 21, 1955 2,828,263 Worth Mar. 25, 1958 2,842,493 Butcosk July 8, 1958 FOREIGN PATENTS 782,879 Great Britain Sept. 11, 1957

Claims (1)

1. A GREASE COMPOSITION COMPRISING: A MINERAL OIL OF LUBRICATING VISCOSITY, A SOAP THICKENING AGENT IN AN AMOUNT SUFFICIENT TO THICKEN SAID MINERAL OIL TO A GREASE, SAID SOAP THICKENING AGENT BEING SELECTED FROM THE GROUP CONSISTING OF A LITHIUM SOAP, A CALCIUM SOAP AND MIXTURES OF LITHIUM AND CALCIUM SOAPS OF AN ALIPHATIC MONOCARBOXYLIC ACID HAVING FROM ABOUT FOURTEEN TO ABOUT TWENTYTWO CARBON ATOMS PER MOLECULE, AND FROM ABOUT ONE TO ABOUT THREE PERCENT BY WEIGHT OF AN IMIDAZOLINE SELECTED FROM THE GROUP REPRESENTED BY THE GENERAL FORMULAE