US3514401A - Greases containing hydrogenated olefin polymer vehicle and organophilic clay thickener - Google Patents

Description

3,514,401 GREASES CONTAINING HYDROGENATED OLE- FIN POLYMER VEHICLE AND ORGANOPHILIC CLAY THICKENER Eldon L. Armstrong, Mullica Hill, and Richard A. Butcosk, Westmont, NJ., and George W. Murray, Pleasant- US. Cl. 252-28 6 Claims ABSTRACT OF THE DISCLOSURE Improved greases, having wide-temperature utility and good oxidation stability, are provided comprising a hydrogenated olefin polymer vehicle and a grease-forming qluantity of a thickening agent comprising an organophilic c ay.

CROSS-REFERENCES TO RELATED APPLICATIONS Continuation-in-part of application Ser. No. 314,575, filed Sept. 26, 1963, and a continuation-in-part of application Ser. No. 563,376, filed July 7, 1966, both applications now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionwhich is a continuation-in-part of our application Ser. No. 314,575, filed Sept. 26, 1963 and a continuation-in-part of our application Ser. No. 563,376, filed July 7, 1966, relates to grease compositions and, in one of its aspects, relates to improved grease compositions which are suitable for use over wide temperature ranges and which exhibit good oxidation stability under varying operational conditions. More particularly, in this aspect, the invention relates to improved grease compositions which contain a combination of certain hydrogenated olefin polymer vehicles and organophilic clay thickening agents, which render these greases particularly ef fective in operations in which the aforementioned conditions are normally encountered.

Description of the prior art Greases heretofore prepared by the processes of the prior art have generally comprised a vehicle, such as petroleum hydrocarbon lubricating oils, refined mineral oils, or synthetic esters, in which various thickening agents, such as metal salts or soaps, are dispersed in grease-forming quantities in such degree as to impart to the resulting grease composition the desired consistency. In this respect, the use of olefin polymers has heretofore been suggested as vehicles for grease formulations. It has ben found, however, that while greases containing olefin polymer vehicles can perform satisfactorily at relatively high temperature ranges, while exhibiting a minimum effect with respect to deterioration of sealant materials, nevertheless, such greases have not been found to exhibit a concomitant good oxidation stability. Thus, the ability to prepare a grease formulation in which each of the aforementioned chraracteristics is present, viz, reduced deterioration of sealant materials and good high temperature performance, is highly desirable from a commercial standpoint. Insofar as thickening agents are concerned, the use of clay thickeners has also been suggested for grease formulations. It has been found, however, that clay thickening agents, in a wide variety, have not exhibited the desired degree of penetration, or minimum leakage or slumping as evidenced by the standard ASTM Wheel Bearing Test.

United States Patent 3,514,401 Patented May 26,1970

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SUMMARY OF THE INVENTION In accordance with the present invention, as more fully hereinafter described, it has been found that improved grease compositions having wide temperature utility, improved oxidation stability and reduced deteriorative effect on sealants, can be produced by employing, as the lubricating vehicle, a hydrogenated olefin polymer, in which the polymer has been prepared from olefins having from about 6 to about 12 carbon atoms per molecule, and by employing as the thickening agent an organophilic clay. In this respect, as also more fully hereinafter described, it has been found that if the hydrogenated olefin polymer is prepared from olefins having less than about 6 carbon atoms per molecule, the resulting grease composition will deteriorate rapidly at elevated temperature due to loss of vehicle by volatilization. On the other hand, it is found that if the hydrogenated olefin polymer is prepared from olefins having more than 12 carbon atoms per molecule, the resulting grease composition will not possess suitable low torque values at relatively low temperatures. With reference to the organophilic clay thickening agent, various types of such clays may be employed. Particularly preferred are organophilic clays which contain predominantly aliphatic quaternary ammonium groups. In this respect, it has been found that if aliphatic quaternary ammonium groups predominate, relatively smaller quantities of the clay thickeners are required for producing an effective grease composition.

As previously indicated, the lubricating vehicles of the improved greases of the present invention, comprise hydrogenated olefin polymers in which the polymer has been prepared from olefins having from about 6 to about 12 carbon atoms per molecule. In one aspect of the invention, the preparation of the lubricating vehicle may be carried out, in general, by distilling a liquid polymerized normal alpha-monoolefin synthetic lubricant to obtain a fraction which contains dimer, and a residual fraction which is essentially free from dimer, and then completely saturating the residual fraction by hydrogenation under catalytic hydrogenation conditions. Thus, the thermally polymerized olefins that are utilizable in producing the synthetic lubricating vehicle in the improved greases of the present invention include, for example, 1- hexene, l-heptene, l-octene, l-nonene, l-decene, l-undecene and l-dodecene. The olefin reactant can be substantially pure normal alpha-monoolefins, mixtures of olefins and/or paraffius containing substantial amounts of normal alpha-monoolefins, having between about 6 and about 12 carbon atoms per molecule.

The aforementioned polymerization procedure can, in general, be carried out over a wide temperature range. More specifically, when catalytic polymerization is to be conducted, polymerization temperatures from about 0 F. to about 450 F. are preferably employed. When thermal polymerization is to be conducted, polymerization temperatures from about 500 F. to about 700 F. are preferably employed. The polymerization period may vary from about 1 hour to as high as about 20 hours, or longer. The above-indicated polymerization procedures are more fully described in US. Pat. 3,149,178.

The aforementioned normal alpha-monoolefins, employed for producing the polymer oil vehicles of the greases of the present invention, may be polymerized in the presence of ditertiary alkyl peroxide catalysts, such as are described in US. Pat. No. 2,937,129. Particularly preferred are the di-tertiary lower alkyl peroxides as catalysts. Of these, the most outstanding catalyst is di-ter tiary butyl peroxide. The amount of peroxide catalyst employed is from about 0.01 to about 0.3 mole per mole of normal alpha-monoolefin reactant. The temperature employed is the activation temperature of the peroxide catalyst, and can vary from about 100 C. to about 200 C. In general, the reaction time will vary from about one to about six hours.

The polymerized normal alpha-monoolefin oils utilizable in obtaining the lubricating vehicles of the present invention can also be readily prepared in the presence of Friedel-Crafts catalysts under relatively mild conditions, as described in US. Pat. 3,149,178. To a great extent, the choice of catalyst and of reaction conditions can be made in order to produce polymer lubricants of desired viscosity.

The polymerization of l-decene (or its equivalent), as a representative olefin within the aforementioned C C olefin polymer range, with AlCl catalyst at temperatures below about 70 C. will produce lubricating oils having a kinematic viscosity of 25-45 centistokes at 210 F. In general, such oils are produced by gradually mixing the olefin with 1-3 weight percent (based on total olefin charge) of AlCl over a period of from about 2 to about 6 hours. A preferable procedure involves an incremental addition of olefin to a slurry of catalyst in an inert hydrocarbon, e.g., n-heptane. Polymerization of l-decene (or its equivalent) in the presence of AlCl at temperatures of 100-200 C. produces oils of about 12 centistokes kine matic viscosity, measured at 210 F. A feasible method of operation is to add AlCl rapidly to the olefin, permitting the temperature to rise suddenly to 150 C. or higher. Under these conditions polymerization occurs readily to the extent that most of the olefin is consumed before the reaction mixture reaches the boiling point of decene.

In a preferred modification, when a Bl -catalyzed polymerization procedure is carried out, pressure or a catalyst promoter is necessary in order to produce synthetic lubricants of high quality. Suitable promoters include BF -decanol complex, decanol, acetic acid, and acetic acid-B1 complex. In general, the polymerization is carried out at temperatures below about 60 C. for a total reaction time in the order of about 2 to about 4 hours. When BF polymerization is carried out under pressure, a reaction time of 2 to 4 hours is employed. The pressure, measured in terms of B1 pressure, can vary between about pounds per square inch gauge and about 500 pounds per square inch gauge, or higher. In both types of BF catalyzed polymerization of l-decene (or its equivalent), polymer oils are produced having kinematic viscosities of about 3-12 centistokes at 210 F.

It will be understood, that the term polymerized normal alpha-monoolefin synthettic lubricant as used herein, is intended to denote synthetic lubricants improved by polymerizing the aforementioned normal alpha-monoolefins, having from about 6 to about 12 carbon atoms per molecule, either thermally or catalytically, in the presence of a di-tertiary alkyl peroxide or in the presence of a Friedel-Crafts catalyst, which includes boron trifluoride and aluminum chloride under mild polymerization conditions, as previously indicated. In addition, as contemplated herein, the aforementioned term is intended to exclude polymers which are produced in the presence of other peroxides, such as diacyl peroxides, which polymers contain structural elements of the peroxy catalyst. It has been found, in this respect, that polymers produced in the presence of a di-tertiary alkyl peroxide do not contain structural elements of the peroxide catalyst. In this respect, the latter polymers are the substantial equivalent of thermally polymerized olefins. As previously indicated, when Friedel-Crafts catalysts are employed, the polymerization conditions must be relatively mild.

As previously indicated, the polymerized normal alphamonoolefin synthetic lubricant, to be employed as a vehicle in the novel grease compositions of the present invention, is subjected to saturation by hydrogenation. A more detailed description for conducting such hydrogenation will be found in US. Pat. No. 3,149,178, the subject matter of which is incorporated, in its entirety, in this application, by reference. In general, the hydrogenation treatment, as previously indicated, is carried out under catalytic hydrogenation conditions, effective to produce the desired hydrogenated polymer wherein the polymer, as previously indicated, was prepared from an olefin having from about 6 to about 12 carbon atoms per molecule. Insofar as the aforementioned polymerization technique, itself, is concerned, these procedures are more fully described in US. Pat. No. 2,937,129 and US. Pat. No. 3,149,178, the subject matter of which is incorporated, in its entirety, in this application, by reference.

As previously indicated, the above-described hydrogenated olefin polymer vehicle is combined with a greaseforming quantity of the organophilic clay thickener to produce the novel grease compositions of the present invention. As was also indicated, it is preferred that organophilic clay thickeners be employed which contain predominantly aliphatic quaternary ammonium groups, as more fully hereinafter discussed. Thus, representative organophilic clays which predominate in aliphatic quaternary ammonium groups include dimethyl, ditallow ammonium bentonite clays, or mixture of dimethyl, benzyltallow ammonium bentonite clays and dimethyl, ditallow ammonium bentonite clays. Other organophilic clays which do not contain predominantly aliphatic quaternary groups, may also be employed as thickeners, as for example, dimethyl, benzyl, tallow ammonium bentonite clays. The modified clays contemplated for use as thickening agents in the novel grease compositions of the present invention, may be employed in any amount sufiicient to thicken the hydrogenated olefin polymer vehicle to produce the desired grease. A preferred range for this thickener is from about 5 to about 20 percent, by weight, of the total grease composition.

The organophilic clays, employed as thickeners in the grease compositions of the present invention, are characterized as modified clays, originally exhibiting a substantial base-exchange capacity (of at least 25) in which the exchangeable inorganic cation has been replaced by an onium base of such configuration as to make the surface of the clay particle organophilic and to an extent sufficient to form an onium clay having a substantial gelling characteristic in the polymer vehicle, colloidally dispersed in the vehicle.

The clays which are useful as starting materials for making the modified clay in accordance with this invention are those exhibiting substantial base-exchange properties, and particularly those exhibiting comparatively high base-exchange properties and containing cations capable of more or less easy replacement. The clays particularly contemplated include the montmorillonites, viz, sodium, potassium, lithium and other bentonites, particularly of the Wyoming type; magnesium bentonite (sometimes called hectorite) and saponite; also nontronite and attapulgite, particularly that of the Georgia-Florida type. These clays, characterized by an unbalanced crystal lattice, are believed to have negative charges which are normally neutralized by inorganic cations. As found in nature, therefore, they exist as salts of the weak clay-acid with bases such as the alkalior alkaline-earth metal hydroxides. Bentonites which are particularly useful are the swelling bentonites of the Wyoming type and the swelling magnesium bentonites of the hectorite type.

The base-exchange capacities of the various clays enumerated run from about 25 to about 100, based upon rnilliequivalents of exchangeable base per grams of clay. The montmorillonites have comparatively high baseexchange capacities, viz, 60100. Attapulgite has substantial base-exchange capacity, viz, 25-35. Generally, the

clays of higher base-exchange capacities are particularly useful where high exchange of an organic base for the cation of the clay is desired.

More specifically, and in accordance with illustrative or more readily Na+bentonite- Oi2H25NH3 O1 C12Hz NH +bentonite- Na+C1- embodiments of this invention, a clay of the character 5 described and exhibiting substantial base-exchange capacity, is reacted with an organic compound, more particularly generally defined to as an onium compound, by The resulting dodecylammonium bentonite is visualized the substitution for the clay cation of the cation of the as consisting of y mineral laminae With florganic compound, which cation is of a class referred to ammonium groups fairly regularly distributed over the as an onium base. The present greases are not, howsurfaces and attached by means of the substituted ammoever, restricted to the use of a reaction product of a nium groups, with the hydrocarbon tails extending out base-salt with clay-salt, but includes the reaction product ovalh crystal urfaces s a material is now organo i? b25156 1 an yphilic rather than hydrophilic and as such exhibits in compound has ee defineg Haekhs organic liquids some of the characteristics which the Chemleal Dletlonary Second edmon as A group or untreated clay exhibited in water For exam le it will organic compounds of the type RXH, which are isologs Swen in man I f p of ammonium and contain the element X in its highest d 11 y lqm S an W1 Sta 1e gels Positive valency, viz: an co 01 al dispersions. Such gels are visually homo- Where X is Pentavalent as in ammonium, phospho geneous and often transparent or translucent. They are nium, arsonium, and stibonium; where X is tetravalent thermally Stable P to the bolhng pemt of the hqud as in oxonium, sulfonium, selenonium and stannonium Phase and Show ht'fle tendency to flew or run when compounds; and where X is trivalent, as in iodonium heated. The more dilute systems which are more or less compounds; and that they may be consid d i i liquid have viscosities much higher than those of the compounds f i b i tib i C f liquids themselves, and in most cases exhibit thixotropy -ini m, -yiium. characteristic of the analogous bentonite-water system. j A number of compounds are capable of reacting with clays, particularly-bentonite; it is to be understood, how- DESCRIPTION P C C EM ODIMENTS ever, that various other compounds reactable with clays Th f n of the character described, may be employed. These com- 6 0W1 Hg data and examliles W111 Serve to 1111.18- pounds may include salts of aliphatic, cyclic, aromatic Hate, the Improved grease eompoeltlons of the Present and heterocyclic amines, primary, secondary, and tertiary veetlon and h propertles" Wlth the Parts recorded, amines and polyamines, also quaternary ammon being understood as recorded 1n parts by weight. In order pounds, as well as other monobasic or polybasic Onium to illustrate the markedly lmproved results obtained by o d u h as triphenylalkyl phosphonium or employing, as the vehicle of the novel grease composistibonium-halides, or dialky1-, or idiaryl-sulphonium and tions, a hydrogenated olefin polymer, prepared from oleseleonium halides, and pyrones, such as 2,5-dimethyl fins having from about 6 to about 12 carbon atoms per gamma pyrone hydrochloride. Y molecule, a series of grease compositions were prepared,

As previously mentioned, the untreated sodium bentonf comparative purposes I h f ll i bl 1 ite in contact with water adsorbs large quantities of the amples 2 4 and 3 are illustrative of the improved greases Water and swells forming a e This Swelling has been that are obtained utilizing the aforementioned hydroattributed to the lamellar structure of the clayrnineral genated olefin polymers, as previously described as h and to agsorptlon of Water i p i onto the sirfaces fluid component or vehicle, employing both conventional of the mmeral sheets, thus g1v1ng rise to a separation of ty 6 Honda thickeners as W n a th 1 the sheets as the oriented water layers build up to an P g h e s e oreanop c ay appreciable depth. If the surfaces of the clay laminae t w eners o t e present mventlon' e greases contain organic matter as by the reaction of base amples 2, 4 and 8 are thus compared with conventionalexchange with an organic base, the ability of watermbletype greases welch do not employ F hyfhogeneted cules to be adsorbed is eliminated, and the clay no longer e Polymer v k of the Present mventlon as luustrat' exhibits its former swelling capacity in Water. Thus, ed by Examples 1, f Wyoming bentonite, for example, which is essentially the Example 2 lllustretes a .synthetlc hydrogenated y sodium salt of montmor-illonitic acid, is capableof reactcarbon P y 6 P Iydeceue-I (Polymer A), ing with organic bases or their salts, e.g., vprepared in accordance with the processes described in (1) J the aforementioned. US. Pat. -No. 3,149,178, employing Namentoniw CnHzsNHZEHOE AlCl as the catalyst. As the example d scloses, this C12H25NH3.rbcntnite Na+OH polymer vehicle-1s thlckened wlth a calclum-complex i soap.

TABLEI xam le... yr "2 Type of fluid (parts): Polydecene-l (Polymer A) (hydrogenated) Ester (trimpthylol propane tri eap- 'rylate) Polydecene-l (Polymer B) (hydro- Mineral oil.

Polybuteue Type of thickener (p s):

Calcium complex soap (1) Non-soap thickener (Baragel clay and stabilizer) 2 Lithium soaps Type of antioxidant (part Amine Phenol typ Anti-rust additive TABLE IContinued Example 1 2 3 4 5 6 7 8 9 Properties of fluid:

Vise. index 136 128 136 136 136 129 136 81 Evap. loss at 350 F. (ASTM D972) (wt. percent) 10, 0 6. 7 10. 0 9. 0 l0. 0 (25+) (25+) 9. 0 (25+) Pour point, F. (ASTM 97-52) 65 65 -65 65 65 65 65 Kin. vise. at 210 F. cs. (ASTM D445) 4.01 10. 52 4. 01 4.32 4. 01 3. 3.10 4.32 7.80 Flash point, F. (ASTM 92-57) 450 480 450 455 450 410 310 455 310 Properties of greases:

N LGI consistency grade 2 1 2 2 2 2 2 2 2 Evap. Loss:

At 300 F. (ASTM D972) (wt.

percent) 23. 0 At 350 F. (ASTM D972 (wt.

percent) 5. 7 4. 0 5. 5 7. 4 5. 3 16. 6 67 7. 4 Low temp. torque at 40 F. (ASTM Starting 2, 389 Running 767 Lgsvlgagip. torque at F. (ASTM Starting 2, 507 2, 065 2, 501 2, 832 3, 687 2, 655 Running 4, 425 413 4, 425 206 619 513 Rubber swell. Percent (Fed. Std. 791

Method 3603) 65 6 66 70 23 6 11 High temp. performance (Fed. Std. 791

Method 331):

Endurance life at 350 F., hrs 414, 221 295, 697

Average, hours 1 Calcium acetate monohydrate, 11.6 parts, calcium caprylate, 5 parts, and calcium stearate, 3.7 parts. 2 Baragel clay comprises a mixture of dimethyl, benzyl-tallow ammonium bentonite clay and dunethyl, ditallow ammonium bentonite clay.

Example 4 illustrates a synthetic hydrogenated hydrocarbon polymer vehicle, viz, polydecene-l (Polymer B), prepared in accordance with the process described in the aforementioned US. Pat. No. 3,149,178, employing BF as the catalyst. This polymer is thickened with an organophilic clay thickener and may be compared with Example 3, showing the same thickener employed with a conventional-type ester fluid. It will be noted that the grease of Example 4 exhibits superior running torque at 65 F rubber swell, and high temperature performance at 350 F., and has comparable consistency, evaporation and starting torque properties.

The greases of Examples 6, 7 and 9 may be compared with the grease of Example 8 to show the superiority of the latter. The grease of Example 8 is the only grease which, simultaneously, exhibits a low rubber swell, low torque at -65 -F., and low evaporation at 350 F. The other greases of Examples 6, 7 and 9 may exhibit one or more of these desirable properties, but not all of them. This is clearly indicative of the unexpected superiority of the greases of the present invention over conventional-type greases prepared from esters, diesters, mineral oils, and polybutenes, as examples of conventional vehicles of the prior art. Polymer A of Example 2 has a viscosity of 10.52 cs. at 210 F. viscosity. Polymer B of Examples 4 and 8 has a viscosity of 4.32 cs. at 210 F. .viscosity.

The manufacturing procedure employed in preparing the greases of Examples 1 and 2 comprises adding to a kettle approximately two-thirds of the fluid, the calcium acetate, calcium caprylate, and calcium stearate. This mixture is heated, with constant stirring, to a temperature of 450 F. Thereafter, the balance of the fluid is added and the resulting mixture is cooled to 200 F. The balance of the other ingredients is then added. The resulting mixture is then cooled, with constant stirring, to-

a temperature of about 180 F., and is then passed through a Tri Homo Colloid Mill at 0.002" setting.

The manufacturing procedure employed in preparing the grease of Examples 3, 4, 5, 8 and 9 comprises adding to a kettle about two-thirds of the fluid, the organophilic clay, and the stabilizer (pentaerythritol), which is dissolved in about 5 parts of water. The resulting mixture is then heated, with constant stirring, to a temperature of 320 F. Thereafter, the balance of the fluid is added, and the resulting mixture is cooled, with constant stirring, to a temperature of about 200 F. The balance of the ingredients is next added and the resulting mixture is then cooled, with constant stirring, to a temperature of about 180 F. The product is then passed through a Tri Homo Colloid Mill at a 0.002" setting.

The superiority of the properties of the greases of the present invention, which contain the aforementioned hydrogented olefin polymer vehicles over conventional-type greases which do not contain such vehicles, will, therefore, be apparent from a comparison of the examples described in the above Table I. It will be understood, however, that other hydrogenated olefin polymers may be substituted as the vehicle for those shown in the improved greases of Examples 2, 4 and 8, and prepared from olefins having from about 6 to about 1.2 carbon atoms per molecule.

As previously indicated, the novel grease compositions of the present invention employ a hydrogenated olefin polymer, prepared from olefins having from about 6 to about 12 carbon atoms per molecule. On a comparative basis, in this respect, it is found that a marked distinction exists between grease compositions which con tain the aforementioned hydrogenated olefin polymers and greases which contain olefin polymers within the aforementioned C -C olefin polymer range, but which are non-hydrogenated (unsaturated). Thus, it has been found that the grease compositions of the present invention which contain the hydrogenated C -C olefin polymer vehicles exhibit outstandingly improved oxidation stability over the same grease compositions which contain only non-hydrogenated (unsaturated) olefin polymer vehicles.

In order to demonstrate the aforementioned superiority of the greases of the present invention with respect to improved oxidation stability, eight grease compositions containing both hydrogenated as well as unsaturated olefin polymer vehicles within the aforementioned olefin polymer range were evaluated with respect to oxidation stability, as determined by the standard ASTM bomb test D 942-50 for greases at 210 F.

As is shown in the following Table II, an evaluation was made with respect to determining criticality in oxidation stability for greases which contain the organophilic clay thickeners of the present invention, as well as greases TABLE II.ASTM BOMB TEST DMZ-50 FOR GREASES AT 210 F.

Example 1 2 Gelling agents (wt. percent):

Lithium hydroxy stearate Non-soap thickener (BarageP clay and stabilizer) 1 Fluids (wt. percent):

Polyhexene, unsaturated Polyhexene, hydrogenatetL. Polydecene, unsaturated Polydecene, hydro n ge ated ASTM Bomb Test at 210 F. (D942-50) p.s.i.g.

drop per 24 hours 100 90 Baragel clay comprises a mixture of dimethyl, benzyl-tallow ammonium bentonite clay and dimethyl, ditallow ammonium bentonite clay.

As will be noted from the foregoing Table II, when lithium hydroxy stearate was employed as the thickening agent in combination with unsaturated polyhexene as a vehicle, the ASTM bomb test revealed a pressure drop of 100 p.s.i.g. as shown in Example 1. On a comparative basis, as shown in Example 3, the same grease in which the polyhexene vehicle was hydrogenated revealed a significantly improved pressure drop of only 97 p.s.i.g. It will also be noted that when a clay thickener was substituted for the lithium hydroxy stearate, as shown in Example 2, a pressure drop of 90 p.s.i.g. was obtained employing the unsaturated polyhexene vehicle. On the TABLE IIL-EFFECT OF THICKENER TYPE 0N GREASE CONSI AND PERFORMANCE IN THE ASTM WHEEL BEARING TE S T Example No 1 2 3 Synthetic hydrocarbon Thiekener A- Thickener B Thickener O Structure modifier Antioxidants I Dispersant for E.P. 3 Additive u ASTM penetration, unworked/w0rked 279/306 281 23g 430 4 O ASTM wheel bearmg test (13-1263) 4 No leakag 5 f jl Hydrogenated polydecene. 2 Pentaerythritol.

a N-oleoyl sarcosin 4 ASTM Staudarts (1964) part 18 p. 515-521. 5 Did not slump. Slumped out of hub.

other hand, as is shown in Example 4, when hydrogenated polyhexene was substituted as the vehicle in this same grease composition, a pressure drop of '0 was obtained. Thus, it will be seen that the hydrogenated polyhexene vehicle in the same grease composition represents a marked improvement in diminished pressure drop over the same grease which contains the unsaturated polyhexene vehicle, as revealed by the standard ASTM bomb test.

Referring once more to the foregoing table, it will be noted that when lithium hydroxy stearate was employed as a gelling agent in combination with unsaturated polydecene as a vehicle, the ASTM bomb test revealed a pressure drop of 98 p.s.i.g., as shown in Example 5. On a comparative basis, as shown in Example 7, the same grease in which the polydecene vehicle was hydrogenated revealed a significantly improved pressure drop of only 64 p.s.i.g. It will also be noted that when the organophilic clay thickener was substituted for the lithium hydroxy stearate, as shown in Example 6, a pressure drop of 98 p.s.i.g. was obtained employing the unsaturated polydecene vehicle. On the other hand, as is shown in Example 8, when hydrogenated polydecene was substituted as the vehicle in this same grease composition, a pressure drop of 0 p.s.i.g. was obtained. Thus, it will be seen here also that the hydrogenated polydecene vehicle in the same grease composition represents a marked improvement in diminished pressure drop over the same grease which contains the unsaturated polydecene vehicle, as revealed by the standard ASTM bomb test.

As previously indicated, of the organophilic clay thickening agents of the present invention, clays are preferred in which the quaternary ammonium groups are aliphatic or predominantly aliphatic. As illustrative thereof, three organophilic clay thickeners were evaluated for their Examples 1, 2 and 3 in the above Table III, represent non-extreme pressure greases, in which the only difference resides in the particular organophilic clay thickener. It will be noted from the table that comparable penetrations are obtained with 9% of either thickener A or thickener B and little or no leakage or slumping in the ASTM Wheel Bearing Test. With respect to thickener C, it will be noted that the grease was semi-fluid even though 10% thickener had been used. This grease exhibited excessive bleeding and slumping in the wheel bearing test.

From a comparison of the examples and data hereinbefore set forth, it will be apparent that the superiority of the properties of the greases of the present invention, which comprise an effective combination of the specified hydrogenated olefin polymer vehicle and organophilic clay thickeners, over conventional-type greases, which do not employ the aforementioned combination of vehicles and thickener, has been established. It should also be noted, that if so desired, it is possible to blend these improved greases with conventional-type greases for the purpose of upgrading the quality level of the latter. Furthermore, it is also within the scope of the invention to incorporate in these greases additional additives for the purpose of imparting anti-wear, anti-rust and extreme pressure properties, if so desired.

While preferred embodiments of the novel grease compositions of the present invention, and the method for their preparation, have been described for purposes of illustration, it will be understood that various modifications and adaptations thereof, which will be obvious to those skilled in the art, may be made without departing from the spirit of the invention.

We claim:

1. A grease composition comprising a hydrogenated olefin polymer vehicle, said polymer having been prepared 1 1 from an olefin having from about 6 to about 12 carbon atoms per molecule, and a grease-forming quantity of a thickening agent comprising an organophilic clay containing predominantly alkyl quarternary ammonium groups.

2. A grease composition as defined in claim 1 in which said hydrogenated olefin polymer vehicle is prepared by distilling a dimer-containing liquid polymerized normal alpha-monoolefin having from about 6 to about 12 carbon atoms per molecule, to produce a dimer-free residual fraction containing said monoolefin, and hydrogenating the residual fraction thus produced.

3. A grease composition as defined in claim 1 in which said organophilic clay is present in an amount from about 5 to about 20 percent, by weight.

4. A grease composition as defined in claim 1 in which the organophilic clay comprises a dimethyl, ditallow ammonium bentonite clay.

5. A grease composition as defined in claim 1 in which the organophilic clay comprises a mixture of dimethyl, benzyl-tallow ammonium bentonite and dimethyl, ditallow ammonium bentonite clays.

6. A grease composition as defined in claim 1 in which the vehicle comprises hydrogenated polydecene and the thickening agent comprises a dimethyl, ditallow ammonium bentonite clay.

References Cited UNITED STATES PATENTS 2,500,244 3/ 1950 Doherty 252-59 2,554,222 5/ 195 1 Stross 252-28 2,748,081 5/1956 Peterson et a1. 252-28 2,937,129 5/1960 Garwood 208-18 3,100,808 8/1963 Dyer 20 8-18 3,113,167 12/1963 Sauer 252-59 3,149,178 9/ 1964 Hamilton et a1 208-18 3,168,588 2/1965 White et a1. 252-59 3,349,034 10/1967 Butcosk et al 25228 2,629,691 2/ 1953 Peterson 25228 DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner U.S. Cl. X.R. 208-18