US3446739A - Hydrocarbon lubricating compositions containing mixtures of an alkyl phosphite and fatty acid esters for imparting limited-slip properties - Google Patents

Description

United States Patent U.S. Cl. 25249.8 Claims ABSTRACT OF THE DISCLOSURE Hydrocarbon lubricating compositions are provided which contain small amounts for imparting limited-slip properties thereto, of mixtures of an alkyl phosphite and an ester of a fatty acid and a fatty alcohol, wherein alkyl groups of said phosphite and alkyl groups of said fatty acid and said fatty alcohol each contain from about 12 to 30 carbon atoms.

This invention relates to improved organic compositions and, in one of its aspects, relates more particularly to improved organic compositions in the form of liquid and solid hydrocarbon-containing materials which exhibit improved limited-slip properties under conditions of use. Still more particularly, in this aspect, the invention relates to improved organic compositions in the form of lubricating oils and greases which contain additive materials capable of imparting limited-slip properties to such lubricants, but which do not detract from the extreme pressure charac teristics thereof.

Among the desired characteristics of lubricating Oils, and greases containing such oils as lubricating vehicles, is the ability of the lubricant to exhibit both satisfactory extreme pressure properties under such conditions as high-torque low speed and high speed operations, as well as exhibiting limited-slip properties. In this respect, it has been found that while lubricants may exhibit the desired degree of extreme pressure properties, the presence of commercially available additive materials as limited-slip improvers has heretofore been found to detract from the extreme pressure performance of the lubricant and also to impair its stability.

It is, therefore, an object of the present invention to provide organic compositions which contain additives effective for imparting limited-slip properties thereto, but which do not detract from the extreme pressure properties of such compositions.

Another object of the invention is to provide improved organic compositions in the form of liquid and solid hydrocarbon-containing materials as lubricants, which possess the aforementioned desired extreme pressure properties and in which additives employed for imparting limitedslip properties thereto do not detract from their extreme pressure properties.

Still another object of the invention is to provide an additive composition which, when incorporated into the aforementioned organic lubricant compositions, can result in imparting limited-slip properties thereto, without detracting from their extreme pressure properties or impairing their stability.

Other objects and advantages inherent in the invention will become apparent to those skilled in the art from the following detailed description.

It has now been found that the aforementioned objectives and desired properties of organic compositions, particularly in the form of liquid and solid lubricants, can be achieved by incorporating therein small amounts of a mixture comprising an alkyl phosphite and an ester of a fatty acid and a fatty alcohol, wherein alkyl groups of the phosphite and alkyl groups of the fatty acid and the fatty alcohol each contain from about 12 to about 30 carbon atoms. In general, as more fully hereinafter described, the present invention, in its preferred applications, contemplates organic compositions exhibiting effective extreme pressure properties under varying operating conditions, and which also contain a small amount of the abovedescribed additive limited-slip improver mixture, usually from about 0.1 percent to about 40 percent, by weight, and preferably from about 0.5 percent to about 10 percent by weight, of the total weight of such composition. Insofar as the additive mixture itself is concerned, the alkyl phosphite is present in an amount from about 10 percent to about percent, by weight, and, correspondingly, the ester is present in an amount from about 90 percent to about 10 percent, by weight, of the total weight of said mixture.

A field of specific applicability is the improvement of liquid hydrocarbons employed as lubricants, including any of the conventional hydrocarbon oils of lubricating viscosities. These may include mineral or synthetic lubricating oils, aliphatic phosphates, esters and diesters, silicates, siloxanes, oxalkyl ethers, or esters. Mineral lubricating oils employed as the lubricating composition may be of any suitable lubricating viscosity and may range from about 40 SSU to about 6,000 SSU at 100 F., and preferably from about 40 SSU to about 250 SSU at 210 F. These may have viscosity indexes from below 0 to about 100 or higher. Viscosity indexes from about 70 to about are preferred. The average molecular weights of these oils may be, for example, from about 250 to about 800 mineral oils having an SAE grade from about 5 to about 140, and preferably from about 60 to about 120, have been found to possess particular commercial utility as lubricants in which the aforementioned additive mixtures may be incorporated.

As previously indicated, the aforementioned additive mixtures may also be incorporated as limited-slip additives in grease compositions. Such greases may comprise a combination of a wide variety of lubricating vehicles and thickening or gelling agents. Thus, greases in which the aforementioned additive mixtures are particularly effective may comprise any of the aforementioned conventional hydrocarbon oils of lubricating viscosity as the oil Vehicle, and may include any of the aforementioned mineral or synthetic lubricating oils of the type indicated.

With respect to the formation of improved grease com positions in which the aforementioned additive mixtures are to be incorporated, the choice of employing a mineral or a synthetic oil of lubricating viscosity can best be determined from the nature of the intended environmental use for the grease. Thus, when high temperature stability is not a requirement of the finished grease, mineral oils having a viscosity of at least 40 SSU at l00 F., and particularly those falling within the range from about 60 SSU to about 6,000 SSU at F. may be efi'ectively employed. In instances where synthetic vehicles are employed rather than mineral oils, or in combination therewith as the lubricating vehicle, various compounds of this type may be successfully utilized. Typical synthetic vehicles include: polypropylene, polypropylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, di-(ethyl hexyl) sebacate, di-(2-ethyl hexyl) adipate, di-butyl phthalate, fiuorocarb-ons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chain-type polyphenyls, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl ethers exemplified by a butyl-substituted bis(p-phenoxy phenyl) ether, phenoxy phenyl ethers, etc.

The lubricating vehicles of the aforementioned improved greases of the present invention containing the above-described additive mixtures are combined with a grease-forming quantity of a thickening agent. For this purpose, a wide variety of materials may be employed. These thickening or gelling agents may include any of the conventional metal salts or soaps which are dispersed in the lubricating vehicle in grease-forming quantities in such degree as to impart to the resulting grease composition the desired consistency. Other thickening agents that may be employed in the grease formulation may comprise non-soap thickeners, such as surface-modified clays and silicas, aryl ureas, calcium complexes and various other materials. In general, grease thickeners may be employed which do not tend to melt and dissolve when used at the required temperature within a particular environment; however, in all other respects, any material which is normally employed for thickening or gelling hydrocarbon fluids for forming greases, can be used in preparing the aforementioned improved greases in accordance with the present invention.

The alkyl phosphite component of the novel limitedslip improver additives, as previously indicated, may comprise any alkyl phosphite having alkyl groups containing from about 12 to about 30 carbon atoms. Representative examples of these alkyl phosphites are oleyl phosphites, mono (or di) oleyl phosphite; mono (or di) octadecyl phosphite, mono (or di) dodecyl phosphite, mono (or di) hexadecyl phosphite, trioleyl phosphite, trioctadecyl phosphite and tridodecyl phosphite and may include any alkyl group within the aforementioned C to C range, having single or double bonds. There may also be included phosphites having one long-chain alkyl group and the rest of short-chain alkyl groups such as methyl, ethyl, butyl, etc.

The ester component of the novel additive mixtures, as previously indicated, comprises an ester of a fatty acid and a fatty alcohol whose respective alkyl groups contain from about 12 to about 30 carbon atoms and having single or double bonds. Representative examples of these esters are oleyl oleate, stearic stearate, dodecyl oleate, dodecyl dodecate, octadecyl oleate, hexadecyl oleate, hexadecyl hexadecate.

Particularly useful as the ester component are mixtures of such esters commercially available in the form of sperm oil. The composition of the present invention may also contain alkyl acid phosphates containing from about 1 to about 18 carbon atoms, or straight-chain amines containing from about 8 to about 30 carbon atoms.

As previously indicated, the novel additive mixtures of the present invention, when incorporated into lubricant compositions, can impart limited-slip properties thereto, without detracting from their extreme pressure properties or impairing their stability, thus fulfilling a need that has long existed in this specific area .of lubricant application. It is theorized that the efiicacy of these novel additive mixtures can be explained on the basis that although fatty materials including esters of fatty acids and alcohols have, in general, been heretofore employed as limited-slip additives, but which also tend to lower the extreme pressure properties of the lubricant, the presence of the alkyl phosphite component, on the other hand, tends to balance the formulation in performing a two-fold function, viz., that of an extreme pressure agent and friction modifier. Thus, a synergistic effect is believed to exist between the alkyl phosphite and the ester components of the novel additive limited-slip mixtures of the present invention.

The following examples will serve to illustrate the eflicacy of the novel limited-slip additives of the present invention when incorporated into finished MILL-2105B lubricant compositions, without impairing their extreme pressure properties or affecting their stability. Each of the lubricant compositions formulated was subjected to the standard CRC L-37 high-torque low speed 4 gear test and standard CRC L-42 high speed and shock test of standard specification MIL-L-210'5B.

Example 1 An SAE base lubricating oil containing, besides the MIL-L-ZLOSB additive package, 3 percent, by Weight, of a mixture of dioleylphosphite and sperm oil (in a weight ratio of 2: 1) was separately subjected to both the aforementioned CRC L37 and CRC L-42 tests, and in each instance were found to meet the requirements of standard specification MIL-L-2l05B for gear lubricants.

' Example 2 An SAE 90 base lubricating oil containing on top of the normal MIL-L-ZIOSB additive package, a 3.4 percent, by weight, of the aforementioned mixture of the dioleylphosphite and sperm oil of Example 1 and also oleylamine (at a weight ratio of dioleylphosphite and sperm oil to oleylamine of 2:1 to 0.4) was separately subjected to both the aforementioned CRC L-37 and CR0 L-42 tests, and in each instance were found to meet the requirements of standard specification MIL-L-ZlOSB for gear oil lubricants, and thus establishing its fitness for factory fill use of limited-slip as well as conventional axles.

Example 3 In order to test the limited-slip properties of lubricants containing the aforementioned novel additive mixtures of the present invention, the same lubricant composition tested in accordance with Example 1, above, was subjected to the following full-scale limited-slip test.

Batches of the aforementioned gear oil lubricant were tested in the limited-slip differentials of both a 1966 and 1967 Oldsmobile. The respective automobiles were run over a figure-8 course at low average speed for a distance of 400 miles. During these runs, observations were made for detecting any noise or chatter emanating from the differentials. The presence of noise or chatter is indicative of a deficiency in the oil. During the respective 400 mile runs, no noise or chatter was observed at any time.

The above-described test runs were then repeated with the oil being maintained at a temperature of 250 F. (by insulating the axles of the respective automobiles) to determine the thermal stability of the oil. In this respect, it is noted that while a lubricant might exhibit effective limited-slip properties at a relatively low temperature, the lubricant, however, might degenerate at a relatively high temperature. In the present runs, no noise or chatter was observed at any time during the respective runs in which the oil was maintained at the aforementioned relatively high temperature of 250 F.

Example 4 A lubricant composition was prepared similar to that described in Example 1, above, except that in place of the limited-slip additive mixture of the dioleylphosphite and sperm oil, there was incorporated in an amount of 5 percent, by weight, a commercially available limitedslip additive formulation having the following properties.

Specific gravity .92 Viscosity (SUS at 210 F.) 49.0 Lbs/gal. 7.7 Phosphorus content, percent 2.2 Nitrogen content 0.46 Neutralization number 76.2

A commercially available factory fill limited-slip lubricant composition consisting of a MILL2105B gear oil-based on zinc dialkyl dithiophosphate-sulfur-chlorine formula and a limited slip additive having the following analysis in percent by weight:

Sulfur 2.25-2.70 Phosphorus 0.30-0.31 Chlorine 1.50-1.55 Nitrogen 0.09 Zinc 0.300.33

was also tested, failed both the CRC L-37 and CRC L-42 tests. This oil was also found to be unsatisfactory in the 400 mile accelerated limited slip tests.

As will be seen from the data of the foregoing examples, the improved organic compositions of the present invention, containing the aforementioned novel limitedslip additive mixtures, are outstandingly effective in obtaining satisfactory performance as lubricants over a wide area of operating conditions, and effectively meet the requirements of standard tests. The same advantages are also realized when lubricating oils containing the abovedescribed improved limited-slip additive mixtures are formulated with desired thickening agents to produce improved solid lubricants, as in the formulation of grease compositions. It will be understood, moreover, that the improved organic compositions of the present invention may, if so desired, contain various other additives or mixtures of such additional additives in order to further enhance their properties. Thus, the organic compositions of the present invention may also contain such additives as extreme pressure agents, antioxidants, detergents, antiwear agents, anti-foam agents, anti-rust agents and the like. In addition, other limited-slip additives, such as long-chain amines or their derivatives, long-chain phosphates or phosphites or their derivatives, metal salts or their derivatives, long-chain glycerides, and long-chain carboxylic acids or their derivatives, can also be incorporated into the limited-slip additive compositions of the present invention.

It will be understood that although the present invention has been described with preferred embodiments, various modifications and adaptations thereof may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand.

I claim:

1. Hydrocarbon lubricant compositions containing a small amount, sufiicient to impart limited-slip properties thereto, of a mixture comprising an alkyl phosphite and an ester of a fatty acid and a fatty alcohol, wherein alkyl groups of said phosphite and alkyl groups of said fatty acid and said fatty alcohol each contain from about 12 to about 30 carbon atoms.

2. A composition as defined in claim 1 wherein said mixture is present in an amount from about 0.1 percent to about 40 percent, by weight, of the total weight of said composition.

3. A composition as defined in claim 1 wherein said mixture is present in an amount from about 0.5 percent to about 10 percent, by weight, of the total weight of said composition.

4. A composition as defined in claim 1 wherein said mixture contains from about 10 percent to about percent, by weight, of said alkyl phosphite and, correspondingly, from about 90 percent to about 10 percent, by weight, of said ester.

5. A composition as defined in claim 1 wherein said alkyl phosphite is selected from the group consisting of oleyl phosphites, dodecylphosphites, hexadecylphosphites, octadecylphosphites, methyl octadecylphosphites, methyl oleyl phosphite, dimethyl oleyl phosphites and dioleyl methyl phosphites.

6. A composition as defined in claim 1 wherein said ester comprises a sperm oil.

7. A grease composition containing a mixture as defined in claim 1.

8. A composition for imparting limited-slip properties to hydrocarbon lubricants comprising from about 10 percent to about 90 percent, by weight, of an alkyl phosphite and, correspondingly, from about 90 percent to about 10 percent, by weight, of an ester of a fatty acid and a fatty alcohol, wherein alkyl groups of said phosphite and alkyl groups of said fatty acid and said fatty alcohol each contain from about 12 to about 30 carbon atoms.

9. A composition as defined in claim 8 wherein said alkyl phosphite is selected from the group consisting of oleyl phosphites, octadecyl phosphites, dodecyl phosphites or mixed alkyl phosphites and said ester comprises a sperm oil.

10. A composition as defined in claim 8 wherein said composition also contains at least one member of the group consisting of alkyl acid phosphates containing from about 1 to about 18 carbon atoms and straight-chain amines containing from about 8 to about 30 carbon atoms.

References Cited UNITED STATES PATENTS 3,009,939 11/1961 Friedman 3,236,771

252-78 2/1966 Matson 252-78 US. Cl. X.R.