US3846314A - Grease thickened with ureido compound and alkaline earth metal aliphatic carboxylate - Google Patents

Abstract

1. A GREASE COMPOSITION COMPRISING A MAJOR PART OF A LUBRICATING OIL CONTAINING (1) FROM 0.5 TO 10 WEIGHT PERCENT OF A MON OR POLYUREA COMPOUND OR MIXTURE OF MONO OR POLYUREA COMPOUNDS HAVING FROM 1 TO 8 UREIDO GROUPS AND HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 375 AND 2,500 AND (2) FROM 3 YO 30 WEIGHT PERCENT OF AN ALKALINE EARTH METAL ALIPHATIC MONOCARBOXYLATE HAVING FROM 1 TO 3 CARBONS, WHEREIN THE WEIGHT RATIO OF ALKALINE EARTH METAL CARBOXYLATE TO MONO AND POLYUREA COMPOUNDS IS FROM 1 TO 15.

Description

Patented Nov. 5, 1974 U.S. Cl. 252-18 19 Claims ABSTRACT OF THE DISCLOSURE A novel grease composition is prepared by admixing a lubricating oil with 0.5 to weight percent of a mono or polyurea compound having from 1 to 8 ureido groups and having a molecular weight between about 375 to 2500 and from 3 to 30 weight percent of an alkaline earth metal aliphatic monocarboxylate having from 1 to 3 carbon atoms and wherein the weight ratio of alkaline earth metal carboxylate to mono and polyurea compounds is from 1 to 15.

This invention relates to a new grease composition. More particularly, this invention relates to an improved grease lubricant containing a polyurea thickening agent.

CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of application Ser. No. 244,864, filed Apr. 17, 1972, now abandoned.

BACKGROUND OF THE INVENTION Modern technology is currently supplying the general public and the process industries with machinery which is designed to operate under a wider range of temperatures and under greater loads than previously available. In addition, many of the newer machines are designed to operate at extremely high speeds. Many of these machines require certain specific lubricating properties which are not available in the conventional lubricants. Thus, modernization of high speed and high temperature equipment has strained the petroleum industry for the development of a second generation of lubricants capable of satisfying the requirements of the new machines. Recently, for example, there has been an increased demand for lubricants capable of performing well at temperatures above 300 F. in high speed bearings and gears for periods in excess of 500 hours. In addition, with the further development of the high speed sealed bearings, the lubricant must be able to endure for the life of the bearing.

There have been numerous grease compositions developed which satisfy most of the new more stringent requirements. Many of these compositions, however, are entirely too expensive for commercialization or only meet some of the lubricating requirements and fail in others. One type of lubricant currently available is the ubiquitous lithium greases. These greases are simply a mixture of a hydrocarbon base oil and lithium hydroxy stearate with minor amounts of other additives. Although these greases exhibit good lubricating properties and perform well at moderate temperatures, their application in high temperature and high speed machinery has not been entirely successful. The lithium greases tend to deteriorate in these machines at high temperatures, particularly at temperatures above 350 F. The deterioration leads to a rapid loss of lubrication and ultimately failure of the equipment.

Another type of grease composition which has excellent lubricating properties at the higher temperatures is comprised of a lubricating oil (natural or synthetic) containing a polyurea additive. This type of lubricant is disclosed in U.S. Pat. Nos. 3,242,210; 3,243,372; 3,346,497; and 3,401,027, all assigned to the Chevron Research Company. The polyurea component imparts a significant high temperature stability to the grease and, in fact, effectsa mild anti-thixotropic property, i.e., increases in viscosity with increasing shear, to the lubricant. This property of the lubricant is advantageous to prevent the segregation or loss of grease from the moving parts of the machine. While this grease has solved most of the problems associated with the older lubricants, it is handicapped by the requirement of relatively large amounts of polyurea (between 8 and 20 weight percent) and its relatively high costs. In addition, the polyurea component does not impart extreme pressure properties to the lubricant and, accordingly, EP additives must be added in applications involving high contact pressures. A need therefore exists for a grease composition which can be used in high temperature and high speed applications, that exhibits good stability over prolonged periods, that exhibits both extreme pressure and antiwear properties, and that is relatively inexpensive to produce.

It is, therefore, an object of this invention to provide a new improved grease composition.

It is another object of this invention to provide an improved grease composition capable of performing well at high temperatures for prolonged periods.

It is another object of this invention to provide a relatively inexpensive grease composition capable of performing well at high temperatures in high speed application and which exhibits good EP properties.

It is another object of this invention to provide a method of making an improved grease composition.

SUMMARY OF THE INVENTION The aforegoing objects and their attendant advantages can be realized by a composition comprising a major part of a lubricating oil containing (1) from 0.5 to 10 weight percent of a mono or polyurea compound or mixture of mono or polyurea compounds having from 1 to 8 ureido groups and having a molecular weight between about 375 and 2,500 and (2) from 3 to 30 weight percent of an alkaline earth metal aliphatic monocarboxylate having from 1 to 3 carbon atoms, wherein the weight ratio of alkaline earth metal carboxylate to mono and polyurea compounds is from 1 to 15.

By incorporating an alkaline earth metal carboxylate within the grease composition, we have found that the mono or polyurea content may be reduced by 50 percent of that required in the prior mono or polyurea lubricants for the same dropping point and other physical properties. Moreover, the presence of the metal carboxylate imparts good extreme pressure properties to the lubricant and thus the addition of other EP additives is not necessary in many applications.

The exact mechanism of the mono or polyurea compound and the metal carboxylate in effecting the improved lubricating properties is unknown. However, without being bound by the theory, it is believed that the metal carboxylate complexes in some manner with the mono or polyurea compound to elfect a combined thickening action. Although the mechanism is unknown, it is known that a synergism exists between the two components such that the lubricating properties of the grease are substantially improved over either the mono or polyurea or metal carboxylate employed alone. For example, the combination effects a remarkable increase in the antiwear properties of the grease.

Polyurea Component The mono or polyurea component of this invention is a water and oil insoluble organic compound having a molecular weight betweenabout 375 and 2,500 and having at least one ureido group and preferably between about 2 and 6 ureido groups. A ureido group as referred to herein is defined as I. A diisocyanate having the formula: OCNR-NCO wherein R is a hydrocarbylene having from 2 to 30 carbons and preferably from 6 to 15 carbons and more preferably 7 carbons.

II. A polyamine having a total of 2 to 40 carbons and having the formula:

Bo Bo Bo H il IR1 l IR2I I- N N\E X y L wherein R and R are the same or different type of hydro carbylenes having from 1 to 30 carbons and preferably from 2 to 10 carbons and more preferably from 2 to 4 carbons; R is selected from hydrogen or a C C, alkyl and preferably hydrogen; x is an integer from 0 to 2; y is 0 or 1 and z is an integer equal 0 when y is 1 and equal to 1 when y is 0.

III. A monofunctional compound selected from the group consisting of monoisocyanate having 1 to 30 carbons, preferably from to 24 carbons, a monoamine having from 1 to 30 carbons preferably from 10 to 24 carbons, and mixtures thereof.

The reaction can be conducted by contacting the three reactants in a suitable reaction vessel at a temperature between about 60 to 320 F., preferably from 100 to 300 F. for a period from 0.5 to 5 hours and preferably from 1 to 3 hours. The molar ratio of the reactants present usually varies from 0.1-2 moles of monoamine or monoisocyanate and 0-2 moles of polyamine for each mole of diisocyanate. When the monoamine is employed, the molar quantities are preefrably (n+1) moles of diisocyanate, (n) moles of diamine and 2 moles of monoamine. When the monoisocyanate is employed, the molar quantities are preferably (n) moles of diisocyanate, (n+1) moles of diamine and 2 moles of monoisocyanate.

A particularly preferred class of mono or polyurea compounds has structures defined by the following general formulae:

4 wherein:

n is an integer from 0 to 3;

R is the same or different hydrocarbyl having from 1 to 30 carbon atoms, preferably from 10 to 24 carbons;

R is the same or different hydrocarbylene having from 2 to 30 carbon atoms, preferably from 6 to 15 carbons; and

R is the same or different hydrocarbylene having from 1 to 30 carbon atoms, preferably from 2 to 10 carbons.

As referred to herein, hydrocarbyl is a monovalent organic radical composed of hydrogen and carbon and may be aliphatic, aromatic or alicyclic or combinations thereof, e.g., aralkyl, alkyl, aryl, cycloalkyl, alkylcycloalkyl, etc., and may be saturated or olefinically unsaturated (one or more double bonded carbons, conjugated or nonconjugated). The hydrocarbylene, as defined in R and R above, is a divalent hydrocarbon radical which may be aliphatic, alicyclic, aromatic or combinations thereof, e.g., alkylarylene, aralkylene, alkylcycloalkylene, cycloalkylarylene, etc., having its two free valences on different carbonatoms.

The mono or polyureas having the structure presented in Formula 1 above are prepared by reacting (n+1) moles of diisocyanate with two moles of a monoamine and (n) moles of a diamine. (When n equals zero in the above Formula 1, the diamine is deleted.) Mono or polyureas having the structure presented in Formula 2 above are prepared by reacting (n) moles of a diisocyanate with (n+1) moles of a diamine and two moles of a monoisocyanate. (When n equals zero in the above Formula 2, the diisocyanate is deleted.) Mono or polyureas having the structure presented in Formula 3 above are prepared by reacting (11) moles of a diisocyanate with (11) moles of a diamine and one mole of a monoisocyanate and one mole of a monoamine. (When n equals zero in Formula 3, both the diisocyanate and diamine are deleted.)

In preparing the above mono or polyureas, the desired reactants (diisocyanate, monoisocyanate, diamine and monoamine) are admixed within a suitable reaction vessel in the proper proportions. The reaction may proceed without the presence of a catalyst and is initiated by merely contacting the component reactants under conditions conducive for the reaction. Typical reaction temperatures range from 20 C. to C. under atmospheric pressure. The reaction itself is exothermic and, accordingly, by initiating the reaction at room temperature, elevated temperatures are obtained. However, external heating or cooling may be desirable.

Reactants The monoamine or monoisocyanate used in the formulation of the mono or polyurea will form the terminal end groups. These terminal end groups will have from 1 to 30 carbon atoms, but are preferably from 5 to 28 carbon, and more desirably from 6 to 25 carbon atoms.

Illustrative of various monoamines are pentylamine, hexylamine, heptylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, dodecenylamine, hexadecenylamine, octadecenylamine, octadecadienylamine, abietylamine, aniline, toluidene, naphthylamine, cumylamine, bornylamine, fenchylamine, tertiary butyl aniline, benzylamine, beta-phenethylamine, etc. Particularly preferred amines are prepared from natural fats and oils or fatty acids obtained therefrom. These starting materials can be reacted with ammonia to give first amides and then nitriles. The nitriles are then reduced to amines, conveniently by catalytic hydrogenation. Exemplary amines prepared by the method include stearylamine, laurylamine, palmitylamine, oleylarnine, petroselinylamine, linoleylamine, linolenylamine, eleostearylamine, etc. The unsaturated amines are particularly preferred.

Illustrative of monoisocyanates are hexylisocyanate, decylisocyanate, dodecylisocyanate, tetradecylisocyanate, hexadecylisocyanate, phenylisocyanate, cyclohexylisocyanate, xyleneisocyanate, cumeneisocyanate, abietylisocyanate, cyclooctylisocyanate, etc.

The polyamines, which form the internal hydrocarbon bridges between the ureido groups usually contain from 2 to 40 carbons and preferably from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms. Exemplary polyamines include diamines such as ethylenediamine, propanediamine, butanediamine, hexanediamine, dodecanediamine, octanediamine, hexadecanediamine, cyclohexanediamine, cyclooctanediamine, phenylenediamine, tolylenediamine, xylylenediamine, dianiline methane, ditoluidinemethane, bis(aniline), bis(toluidine), piperazine, etc., triamines, such as aminoethyl piperazine, diethylene triamine, dipropylene triamine, N methyl diethylene triamine, etc., and higher polyamines such as triethylene tetramine, tetraethylene pentamine, pentaethylene hexa mine, etc.

Representative examples of diisocyanates include hexanediisocyanate, decanediisocyanate, octadecanediisocyanate, phenylenediisocyante, tolylenediisocyanate, bis(diphenylisocyanate), methylene bis(phenylisocyanate), etc.

Another preferred class of mono-polyurea compounds which may be successfully employed in the practice of this invention include the following:

wherein:

n is an integer of 1 to 3, R is defined supra; X and Y are monovalent radicals selected from Table I below.

In the Table, R is defined supra, R is the same as R; and defined supra, R is selected from the group consisting of arylene radicals of 6 to 16 carbon atoms and alkylene groups of 2 to 30 carbon atoms, and R is selected from the group consisting of alkyl radicals of having from 10 to 30 carbon atoms and aryl radicals having from 6 to 16 carbon atoms.

Mono or polyurea compounds described by the above formula (4) can be described as amides and imides of mono, di, and tri ureas. These materials are formed by reacting in the selected proportions of suitable carboxylic acids or internal carboxylic anhydrides, with a diisocyanate and a polyamine with or without a monoamine or monoisocyanate. The mono or polyurea compounds are prepared by blending the several reactants together in a suitable reaction vessel and heating them to a temperature ranging from 70 F. to 400 F. for a period sufficient to cause formation of the compound, generally from 5 minutes to 1 hour. The reactants can be added all at once or sequentially.

Suitable carboxylic acids include aliphatic carboxylic acids of about 11 to 31 carbon atoms and aromatic carboxylic acid of 7 to 17 carbon atoms. Examples of suitable acids include aliphatic acids such as lauric, myristic, palmitic, margaric, stearic, arachidic, behenic, lignoceric acid, etc.; and aromatic acid such as benzoic acid, l-naphthoic acid, Z-naphthoic acid, phenylacetic acid, hydrocinnamic acid, cinnamic acid, mendelic acid, etc. Suitable anhydrides which may be employed are those derived from dibasic acids which form a cyclic anhydride structure, for example, succinic anhydric, maleic anhydride, phthalic anhydride, etc. Substituted anhydrides, such as alkenyl succinic anhydride of up to 30 carbon atoms are further examples of suitable materials.

Examples of suitable diisocyanates, monoisocyanates, monoamines and polyamines are described supra.

The mono or polyurea compounds are generally mixtures of compounds having structures wherein n varies from 0 to 4, or n varies from 1 to 3, existent within the grease composition at the same time. For example, when a monoamine, a diisocyanate and a diamine are concurrently present within the reaction zone, as in the preparation of mono or polyureas having the structure shown in Formula 2, some of the monoamine may react with both sides of the diisocyanate to form a diurea. In addition to the formulation of diurea, simultaneous reactions can be occurring to form the tri, tetra, penta, hexa, octa, etc., ureas. Particularly good results have been realized when the polyurea compound has an average of four ureido groups.

The amount of mono or polyurea compound in the final grease composition will be sufiicient to thicken the base oil to the consistency of grease when combined with the alkaline earth metal carboxylate. Generally, the amount of mono or polyurea will range from 1 to 15 weight percent and preferably from 2 to 7 weight percent of the final grease composition.

In instances where an oil concentrate is desired, the concentration of the mono or polyurea compound in the base oil or an oleaginous organic liquid can vary between about 10 and 30 weight percent of the final concentrate. The employment of concentrates provides a convenient method of handling and transporting the mono or polyurea compounds for subsequent dilution and use.

Alkaline Earth Metal Aliphatic Monocarboxylate The second component of the grease composition is an alkaline earth metal aliphatic monocarboxylate having from 1 to 3 carbon atoms. Any of the alkaline earth metals can be employed herein, e.g., magnesium, calcium, strontium, barium, etc. However, calcium is the most preferred. The carboxylate group preferably has from 1 to 3 carbon atoms and more preferably 2 carbon atoms. Exemplary compounds which may be successfully employed herein include calcium formate, barium formate, magnesium formate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, calcium propionate, barium propionate, magnesium propionate, etc.

The amount of alkaline earth metal carboxylate present within the grease composition may vary depending upon the lubricating property desired, the particular mono or polyurea constituent selected, the type of alkaline earth metal carboxylate selected, etc. However, generally the metal carboxylate will range from 3 to 30 weight percent of the final grease composition and preferably between about 4 and 15 weight percent. The ratio of alkaline earth metal carboxylate to the mono or polyurea constituent will also vary depending upon the aforementioned conditions, but will generally range on a Weight basis from 1 to 15 parts of metal carboxylate per part of mono and polyurea and preferably from 3 to 7 parts per part of mono and polyurea.

A concentrate of the mono or polyurea compound and metal carboxylate may also be formulated. The concentration of the metal carboxylate can vary from 20 to 50 weight percent and preferably from 25 to 40 weight percent of the concentrate. The base oil is the preferred liquid medium of the concentrate since it can be readily diluted to form the desired grease composition.

Base Oil The third component which must necessarily be present in the composition of this invention is a liquid base oil. The base oils which may be employed herein include a wide variety of lubricating oils such as naphthenic-base, parafiin-base, and mixed-base lubricating oils. Other hydrocarbon oils include lubricating oils derived from ,coal products and synthetic oils, e.g., alkylene polymers (such as, polymers of propylene, butylene, etc., and mixtures thereof), alkylene oxide-type polymers (e.g., alkylene oxide polymers prepared by polymerizing alkylene oxide, e.g., propylene oxide polymers, etc., in the presence of water or alcohols, e.g., ethyl alcohol), carboxylic acid esters (e.g., those which were prepared by esterifying such carboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenyl succinic acid, fumaric acid, maleic acid, etc., with the alcohols such as butyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, etc), liquid esters of acid of phosphorus, alkyl benzenes, polyphenols (e.g., biphenols and terphenols), alkyl biphenols ethers, polymers of silicon, e.g., tetraethyl silicate, tetraisopropyl silicate, tetra(4-methyl-2-tetraethyl) silicate, hexyl(4 methyl-2- pentoxy)disilicone, poly(methyl)siloxane, and polymethylphenyl)siloxane, etc. The base oils may be used individually or in combinations, whenever miscible or whenever made so by use of mutual solvents.

Preparation of Grease Composition The greases exhibiting superior properties of this invention can be prepared by the in situ production of the mono or polyurea compound followed by the production of the alkaline earth metal carboxylate within the base oil. In this embodiment, the base oil is charged to the grease kettle along with the monor or polyurea and metal carboxylate precursors, i.e., the reactants which combine to form the monor or polyurea compound and metal carboxylate. In instances where the preferred monor or polyurea compounds are of the type defined by Formula 1, the base oil is charged with the desired proportion of diisocyanate, diamine, and monoamine. In the preparation of mono or polyurea defined by Formula 2, the base oil is admixed with the desired proportion of diisocyanate, diamine and monoisocyanate. If the monor or polyurea is of the type defined by Formula 3, then the desired proportion of diisocyanate, diamine, monoisocyanate and monoamine are admixed with the base oil. In instances where the monor or polyurea compound is of the type defined in Formula 4, the base oil is charged with the desired proportion of carboxylic acid or anhydride, diisocyanate, diamine, and monoamine or monoisocyanate. The kettle contents are agitated and the temperature is raised to 20 to 160 C. and maintained at that temperature for a period sufiicient to cause formation of the monor or polyurea compound, generally between about 0.5 and 3 hours.

After the formation of the mono or polyurea compound, the grease kettle is charged with an alkaline earth metal hydroxide or oxide and a carboxylic acid. The ratio of alkaline earth metal hydroxide to carboxylic acid on an equivalent basis can vary from 1 to 4:1 and is preferably between 1 and 2:1. The kettle is maintained at a temperature between 70 F. and 150 F. during the process to effect the neutralization reaction of the alkaline earth metal hydroxide or oxide and carboxylic acid. During the reaction water is released and is preferably removed from the system by applying a vacuum on the kettle of 20 to 29 inches of mercury and heating to about 212 F. and higher.

The grease composition can be further processed by subjecting it to shear hardening. Shear hardening is performed by milling the grease in an extrusion type mill under elevated pressures. This milling improves the dispersion of the monor or polyurea and metal carboxylate throughout the base oil resulting in a grease of greatly improved consistency. U.S. application Scr. No. 111,517 filed Feb. 1, 1971, and now abandoned, discloses a preferred method of shear hardening a grease which can be successfully employed for the composition of this invention.

In addition to the mono polyurea and alkaline earth metal carboxylate, other additives may be successfully employed within the grease composition of this invention without affecting its high stability and performance over a wide temperature scale. One type of additive is an antioxidant or oxidation inhibitor. This type of additive is employed to prevent varnish and sludge formation on metal parts and to inhibit corrosion of alloyed bearings. Typical antioxidants are organic compounds containing sulfur, phosphorus or nitrogen, such as organic amines, sulfides, hydroxy sulfides, phenols, etc., alone or in combination with metals like zinc, tin or barium. Particularly useful grease antioxidants include phenyl-alpha-naphthyl amine, bis(alkylphenyl)amine, N,N diphenyl-p-phenylenediamine, 2,2,4 trimethyldihydroquinoline oligomer, bis(4 isopropylaminophenyl)-ethr, Nacyl-p-aminopheno], N acylphenothiazines, N hydrocarbylamides of ethylenediamine tetraacetic acid, alkylphenol-formaldehyde-amine polycondensates, etc.

Another additive which may be incorporated into the grease composition of this invention is an anti-corrodant. The anti-corrodant is employed to suppress attack by acidic bodies and to form protective films over the metal surfaces which decrease the effect of corrosive materials on exposed metallic parts. A particularly effective corrosion inhibitor is an alkali metal nitrite and preferably so dium nitrite. The combination of the polyurea thickener and alkaline earth metal carboxylate has been found to work exceedingly well within the alkali metal nitrite. When this corrosion inhibitor is employed it is usually used at a concentration of 0.1 to 5 weight percent and preferably from 0.2 to 2 weight percent based on the weight of the final grease composition;

Another type of additive which may be employed herein is a metal deactivator. This type of additive is employed to prevent or counteract catalytic effects of metal on oxidation generally by forming catalytically inactive complexes with soluble or insoluble metal ions. Typical metal deactivators include complex organic nitrogen and sulfur-containing compounds such as certain complex amines and sulfides. An exemplary metal deactivator is mercaptobenzothiazole.

In addition to the above, several other grease additives may be employed in the practice of this invention and include stabilizers, tackiness agents, dropping point improvers, lubricating agents, color correctors, odor control agents, etc.

The following examples are presented to illustrate the practice of specific embodiments of this invention and should not be interpreted as limitations upon the scope of the invention.

EXAMPLE 1 In this example, a diurea thickening agent is prepared and its properties tested. A 48 liter stainless steel mixer equipped With a stirrer is charged with 3,750 grams of 126 neutral oil and 305 grams of tall oil fatty amine. The contents are agitated at 130 F. for 30 minutes and thereafter 3,750 grams of additional 126 neutral oil with 95 grams of tolylenediisocyanate are charged to the mixer. The contents are agitated for 40 minutes and recycled through an extrusion type mill at 7,500 p.s.i. for an additional 20 minutes.

The milled grease is then heated to 200 F. and 6 grams of ethylene diamine are charged to the mixer to react with any free isocyanate groups. After being milled at 7,500 p.s.i. for 20 minutes, the grease is cooled to F. and admixed with 2,500 grams of 126 neutral oil and 1,708 grams of hydrated lime (Ca(OH) Thereafter, 3,900 grams of 126 neutral oil and 1,845 grams of acetic acid are charged to the mixture and agitated for a period of about 80 minutes at a temperature of about 150 F.

The mixture is then charged with 200 grams of commercial rust inhibitor and dispersed therein by milling at 7,500 p.s.i. The grease has an ASTM undisturbed penetration (P of 207, and after 60 strokes a worked penetration (P of 348.

9 EXAMPLE 2 This example is presented to demonstrate the preparation of a representative tetraurea-calcium acetate composition of this invention. A 48 liter stainless steel reaction vessel equipped with a stirrer is charged with 7,500 grams of a blend of a parafiinic and naphthenic oil having a viscosity of 78 SSU at 210 F. hereinafter referred to as base oil, 880 grams of tall oil fatty amine and 92 grams of ethylene diamine. The contents of the vessel are stirred for 20 minutes at 130 F. and thereafter admixed with 6,000 grams of base oil and 548 grams of tolylenediisocyanate. The vessel is agitated and held at a temperature of 150 F. for a 30-minute period.

The vessel contents are thereafter milled in an extrusion type mill at a pressure of 7,500 p.s.i. and then heated to 200 F. A small sample of the grease is analyzed and trace amounts of diisocyanate are detected. An additional 40 grams of ethylene diamine are charged to the vessel and mixed with the milled grease for a period of minutes at atemperature of 210 F. At the end of the 10- minute period, the vessel is cooled to 150 F. and 5,000 grams of additional base oil with 2,480 grams of hydrated lime (Ca(OH) are charged to the vessel. The lime and base oil are admixed with the previously milled grease for 5 minutes at which time an additional 5,460 grams of base oil and 2,800 of acetic acid are slowly charged to the vessel over a 25-minute period. The admixture is agitated for 30 minutes at 150 F. to assure that the neutralization reaction between the calcium hydroxide and acetic acid is complete. Thereafter, 320 grams of a commercial rust inhibitor is charged to the vessel and the contents milled at 7,500 p.s.i. The grease is then admixed with -8,920 grams of base oil and recycled through a mill at a pressure of 7,500 p.s.i. The product grease has an undisturbed penetration (P of 232 and after 60 strokes a worked penetration (P of 282 (ASTM-217). The ASTM dropping point is 460 F. (ASTMD2265).

A sample of the grease is calculated to have the folwherein T0 is a tall oil radical.

1 EXAMPLE 3 This example is presented to demonstrate the effectiveness of a representative grease of this invention containing polyurea and an alkaline earth metal carboxylate in long term performance as compared to a typical lithium stearate grease. The polyurea-metal carboxylate grease to be tested is prepared by the method of Example 2. The lithium grease is comprised of the following:

Component: Amount, wt. Lubricating oil 1 87 Commercial E.P. agent concentrate 6 Commercial rust inhibitor 0.3 Lithium hydroxystearate 6 1 The lubricating oil is the same type as employed in Example 2 and has a viscosity of 78 SSU at 210 F.

TABLE II.-TIMKEN TEST RESULTS Load Contact pres- Test grease (1bs.) sure (p.s.i.)

Polyurea-metal carboxylate- 50 32, 000 Lithium 45 12, 000

The Timken test reveals the anti-Wear characteristics of the grease with a higher load and higher contact pressure indicating the better anti-wear properties. It can be seen from the above table that the grease of the instant invention is superior to the lithium grease in passing load and far superior in contact pressure.

The two greases are further subjected to a high temperature thin film test. The thin film test demonstrates the ability of the grease to lubricate a bearing for a long period of time and is indicative of the bearing life. In the thin film test, the two greases are respectively spread in a layer of an inch in thickness on separate strips of steel and exposed in an oven at a temperature of 300 F. The greases are observed over a period of time and that time when the grease loses its grease-like characteristics (becomes hard or turns to lacquer upon cooling) is known as the thin film life.

The aforesaid lithium grease and the grease prepared by the method of Example 2 are subjected to a thin film test and the results are shown in the following Table III.

TABLE III [Thin film lives at 300 F.]

Approxi- Condition of mate life grease at room Grease (hrs.) temperature Lithium hydroxy stearate 300 Hard and cracked- Polyurea-metal carboxylate 1, 000 Grease-like.

It can be seen from the above table that the greases prepared by the practice of this invention are far superior to the conventional lithium hydroxy stearate greases in performance. The table demonstrates a predicted 330 percent increase in bearing life.

EXAMPLE 4 TABLE IV.APPAREN T VISCOSITY Viscosity (poises) At 30 F. At 0 F. Grease 20 sec.- 200 secr 20 sec: 200 sec.-

Polyureametal carboxylate- 900 330 2, 800 1, 200 Lithium 1, 000 400 4, 800 2, 300

As can be seen from the above table, the grease compositions of this invention exhibit a viscosity less than viscosity of the lithium greases at 30 F. and again at 0 F. Particularly significant is the demonstration that at 0 F. the viscosity of the composition of this invention is 2,000 poise less than the lithium grease composition at 20 sec- 1 1 EXAMPLE 5 This example is presented to demonstrate the effectiveness of mono ureas and calcium acetate in making an im- 1 2 eral Test Method 331.1 (Navy High Speed Bearing Test). Each of the following greases is expected to exhibit a relatively good dropping point and a satisfactory bearing life:

TABLE V Mono or polyurea precursors Metal carboxylate precursors Amount, Amount, Composition Type wt. percent Type wt. percent Lube oil type DPM-4,4 diisoeyanate L--- 4 Barium hydroxide 9. 5 1 p-Phenylene diaminc Acetic acid. Octadecylamine p Toluidine 1 2 Hexylisocyanate 2 Dianilinemcthanc- 2. 5 Bis(diphenylisocyanate) 1 Tallow amine 2. 9 IVIagnesium hydrox e 5.0 3 p-Toluidene 1. 2 Propanoic acid 10. 4 Mineral Ethylenediamine. 0. 6 Hexanediisocyanate 4. 3 4 Stearic acid 3. 5 Calclum hydroxldc 6 Tolylene diisocyanate 2. 2 Acetic acid D p-Phenylene diamlne 0. 7 Hydrocinnamic acid 4. 8 Barium hydroxide Phenylene dlisocyanate 2. 5 Acetic acid Alkylmelhyl Naphthylamine 2. 2 Silicone. 6 Maleic anhydride 1. 5 Calcium hydr Deeanediisocyanate-- 2. 4 Acetic acid. Mineral Tall oil fatty amine. 4. 1 7 Tallow amine 3 Tolylene d1is0cya nate- 3. 9 Calcium hydroxide Do.

Diethylene triamme 1. l Acetic acid 5 1 Diphenylmethane, 4,4-diisoeyanate. 1 Pentaerythntol tetracaproate.

proved grease composition. A one-liter Waring Blender is charged with 140 grams of 600 neutral oil and 43.5 grams of tall oil fatty amine at room temperature. While stirring the contents, 19.9 grams of phenyl isocyanate are charged to the blender. The contents are stirred for about 30 minutes and thereafter allowed to stand overnight.

Calcium hydroxide (11 grams) is charged to the blender and intimately mixed within the monourea oil mixture. Thereafter 12.4 grams of acetic acid are contacted with the blender contents and stirred until the neutralization reaction ceases. The mixture is dehydrated and admixed with an additional 50 grams of oil. The grease is then milled and the ASTM work penetration is measured. The penetration after 60 strokes (P is 317. The ASTM Work penetration (P of the mono urea grease without the addition of the calcium acetate is 336.

This example clearly demonstrates an improvement in work penetration by the addition of calcium acetate to the grease composition.

EXAMPLE 6 This example is presented to hypothetically demonstrate the preparation of the various grease compositions of this invent-ion. A Z-gallon grease kettle equipped with cooling jackets and a stirrer is charged with /2-gallon of a lubricating oil at room temperature. The oil is agitated by the stirrer and selected amounts of the mono or polyurea precursors, e.g., diisocyanates, monoisocyanates, diamines, carboxylic acids and monoamines, are slowly charged to the kettle. The amines are charged to the kettle before the addition of the isocyanate and dissolved within the oil. Temperature of the mixture is allowed to increase to 200 F. and thereafter maintained at that temperature. After approximately 30 minutes, the kettle is charged with an additional /2-gallon of lubricating oil containing selected amounts of an alkaline earth metal hydroxide. The contents of the kettle are recycled through a mill at 7,000 p.s.i. to disperse the alkaline earth metal hydroxide throughout the grease composition. Thereafter, a carboxylic acid is charged to the kettle and the contents recycled to a mill at 7,500 p.s.i. for two hours. During the addition of the alkali metal hydroxide and carboxylic acid, the temperature of the kettle is maintained at 200 F.

At the end of the two-hour period, the grease is cooled to ambient temperature and milled twice to an extrusion type mill at 7,000 p.s.i. The milled grease is then tested according to ASTM-D-2265 (dropping point) and Fed- It is apparent that many widely diiierent embodiments of this invetion may be made without departing from the scope and spirit thereof.

We claim:

1. A grease composition comprising a major part of a lubricating oil containing (1) from 0.5 to weight percent of a mono or polyurea compound or mixture of mono or polyurea compounds having from 1 to 8 ureido groups and having a molecular weight between about 375 and 2,500 and (2) from 3 to weight percent of an alkaline earth metal aliphatic monocarboxylate having from 1 to 3 carbons, wherein the Weight ratio of alkaline earth metal carboxylate to mono and polyurea compounds is from 1 to 15. t I

2. The composition defined in Claim 1, wherein said alkaline earth metal aliphatic monocarboxylate is calcium acetate.

3. The composition defined in Claim 2 wherein said mono or polyurea compound or mixture of mono or polyurea compounds have an average from 3 to 4 ureido groups and having molecular weight between about 600 and 1,200 and wherein said lubricating oil is a hydrocarbon oil.

4. A grease composition comprising a major portion of an oil of lubricating viscosity, from 3 to 30 weight percent of an alkaline earth metal aliphatic monocarboxylate having from 1 to 3 carbons and from 0.5 to 10 weight percent of a mono or polyurea compound or mixture of mono or polyurea compounds prepared by reacting the following components:

I A diisocyanate having the formula OCN-R-NCO wherein R is a hydrocarbylene having from 2 to 30 carbons; 1 II A polyamine having a total of 2 to carbons and having the formula:

R0 R0 R0 HI IR1 -I IRzN {N N\ lap/A wherein R and R are the same or difierent type of hydrocarbylene having from 1 to 30 carbons;

R is hydrogen or a C -C alkyl,

x is an integer from O to 2;

y is an integer from 0 to 1; and

z is an integer equal to 0 when y is l and equal to 1 when y is 0; and

IH A monofunctional compound having from 1 to 30 carbons and selected from the group consisting of monoisocyanate, monoamine and mixtures thereof;

wherein the reaction temperature is from about 60 to 320 F., the reaction time is about 0.5 to 5 hours and the component molar ratios of I, H and III are 1, -2 and 0.1-2.

5. The composition defined in Claim 4 wherein said diisocyanate is tolylene diisocyanate, said polyamine is ethylene diamine and said monofunctional compound is a C -C monoamine.

6. The composition defined in Claim 5 wherein the molar ratio of diisocyanate to diamine to monoamine is 2:1:2.

7. The composition defined in Claim 6 wherein said monoamine is tall oil fatty amine.

8. The composition defined in Claim 4 wherein said polyamine is a triamine having from 2 to 40 carbons.

9. The composition defined in Claim 8 wherein said triamine is diethylene triamine.

10. The composition defined in Claim 8 wherein said triamine is tert-N-methyl diethylenetriamine.

11. The composition defined in Claim 4 wherein said polyamine is piperazine.

12. The composition defined in Claim 4 wherein a corrosion inhibiting amount of an alkali metal nitrite is also present.

13. The composition defined in Claim 12 wherein said alkali metal nitrite is sodium nitrite.

14. The composition defined in Claim 4, wherein said alkaline earth metal aliphatic monocarboxylate is calcium acetate.

15. The composition defined in Claim 1 wherein said alkaline earth metal carboxylate is a calcium or barium acetate.

16. The composition defined in Claim 14 wherein said oil of lubricating viscosity is a naphthenic or paraffinic based hydrocarbon lubricating oil or mixture thereof.

17. The composition defined in Claim 16 wherein said diisocyanate is tolylene diisocyanate.

18. The composition defined in Claim 17 wherein said polyamine is ethylene diamine and said monofunctional compound is a C -C monoamine,

19. The composition defined in Claim 18 wherein the molar ratio of said diisocyanate to said polyamine to said monoamine is about 2:1:2.

References Cited UNITED STATES PATENTS 3,182,020 5/1965 Davis 252-51.5 A 3,189,542 6/1965 MorWay et al 252-17 3,278,426 10/1966 Criddle 2525l.5 A 3,361,670 l/1968 Hotten 2525l.5 A 3,376,223 4/1968 Criddle 25251.5 A 3,243,372 3/1966 Dreher et a1 25251.5 A

25 DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner

Claims (1)

1. A GREASE COMPOSITION COMPRISING A MAJOR PART OF A LUBRICATING OIL CONTAINING (1) FROM 0.5 TO 10 WEIGHT PERCENT OF A MON OR POLYUREA COMPOUND OR MIXTURE OF MONO OR POLYUREA COMPOUNDS HAVING FROM 1 TO 8 UREIDO GROUPS AND HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 375 AND 2,500 AND (2) FROM 3 YO 30 WEIGHT PERCENT OF AN ALKALINE EARTH METAL ALIPHATIC MONOCARBOXYLATE HAVING FROM 1 TO 3 CARBONS, WHEREIN THE WEIGHT RATIO OF ALKALINE EARTH METAL CARBOXYLATE TO MONO AND POLYUREA COMPOUNDS IS FROM 1 TO 15.