US2986517A

US2986517A - Solids thickened lubricating greases containing formamide

Info

Publication number: US2986517A
Application number: US713540A
Authority: US
Inventors: Norman R Odell; Joseph F Lyons
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1958-02-06
Filing date: 1958-02-06
Publication date: 1961-05-30
Anticipated expiration: 1978-05-30

Description

United States Patent 9 SOLIDS THICKENED LUBRICATIN G GREASES CONTAINING FORMAMIDE Norman R. Odell, Fishkill, and Joseph F. Lyons, Poughkeepsie, N.Y., assignors to Texaco Inc, a corporation of Delaware No Drawing. Filed Feb. 6, 1958, Ser. No. 713,540

12 Claims. (Cl. 252-28) This invention relates to improved lubricating greases thickened with finely divided solids, and more particularly to such greases containing small amounts of formamide, and to methods of preparing such greases.

We have found, in the preparation of solids thickened greases, that a small amount of formamide present in the grease mixture during the homogenization process assists in the development of the gel structure and very materially improves the yield and stability of the product. This efiect obtained by the use of formamide is unexpectedly very much greater than that obtained with various other liquids such as water, which are commonly employed in solids thickened greases in small amounts to assist in the gel formation.

The solids thickened greases which are benefited by the presence of small amounts of formamide in accordance with this invention are those wherein the solid thickening agent is a finely divided polar material, such as, for example, silica and certain naturally occurring siliceous materials such as bentonite, organo-clays obtained by treating bentonite with amines of various types, organic pigments of various types such as phthalocyanines, indigo, etc., having a measurable surface polarity, and metal oxides of various types such as zinc oxide, magnesium oxide, aluminum oxide, etc., having the property of thickening lubricating oils when they are dispersed therein in finely divided form in suitable proportions. Such materials are suitably employed in the form of particles below about microns in diameter, and usually having a diameter below about two microns in diameter, although the most suitable particle size and form will vary somewhat with the type of material employed.

In general, it is found that the effectiveness of formamide as a yield improving agent increases with increasing polarity of the solid thickening agent. However, special advantages are obtained in certain cases with thickening agents of only relatively low polarity. For example, in the preparation of organo-clay thickened greases employing the so-called in situ process, wherein the organo-clay is formed by treating bentonite with an amine or an amine salt in the presence of lubricating oil comprising all or a portion of the oleaginous liquid component of the grease, it has been found that an unexpected yield advantage is obtained when the formamide is present during the organo-clay reaction. Accordingly, the preparation of such greases wherein an organo-clay is formed in situ in the presence of the formarnide, is regarded as comprising a preferred embodiment of this invention.

The greases of this invention comprise an oleaginous liquid as the chief component, containing about 0.05 to about 5.0 percent of formamide, based on the weight of the grease, and a finely divided solid of the character described above in a sufficient amount to thicken the lubricating oil to a grease consistency with the aid of the formamide which is present. Ordinarily the amount of solid thickening agent is present in amounts from about 5 to about 45 percent by weight, based on the weight of the grease, and preferably in amounts from about 7 to about 2.5 percent by weight, according to the thickening action of the solid and the grease consistency desired. The formamide is preferably employed in an amount between about 0.1 and 3.0 percent of the weight of the grease composition.

The lubricating oils employed in these greases may be any suitable oils of lubricating characteristics ordinarily employed in lubricating greases, including the conventional mineral lubricating oils, synthetic oils obtained by various refinery processes, such as cracking and polymerization, and other synthetic oleaginous compounds, such as high molecular weight ethers, esters, silicones, etc. Suitable mineral oils include paraflinic and naphthenic oils having viscosities in the range from about seconds Saybolt Universal at F. to about 225 seconds Saybolt Universal at 210 F., and are preferably those having viscosities in the range from about 100 to about 600 seconds Saybolt Universal at 100 F.

Additives of the usual types employed in solids thickened greases, including oxidation inhibitors, rust and corrosion inhibitors, extreme pressure agents, etc., may be employed in these greases where no antagonistic effect results between such additive and the formamide. Such materials are employed in minor amounts, such as from about 0.05 to about 10.0 percent by Weight, and preferably in amounts from about 0.5 to about 5.0 percent by weight of the grease. A very suitable class of oxidation inhibitors are the aromatic amines, such as for example, diphenylamine, alphaand beta-naphthylamines and para-phenylenediamine. Very advantageously a compound of the class of higher aliphatic amines and amides, wherein an aliphatic hydrocarbon group contains about 1025 carbon atoms, is employed in the composition in order to improve the water resistance and other properties. We have found that formamide offsets or overcomes the yield depressing effect commonly resulting from the use of compounds of this type in solids thickened greases to a sufiioient extent that solids thickened greases having good Water resistant properties are obtained in satisfactory yields by employing both higher aliphatic amines or amides and a small amount of formamide in the composition.

As an example of a preferred embodiment of this invention, greases were prepared containing a surface treated bentonite as the thickening agent and containing a small amount of formamide, which was present during the bentonite-amine reaction. The preparation of the solid thickening agent was carried out by treating a micron sized bentonite with a commercial quaternary amine salt mixture, comprising about 75 percent by weight of dioctadecyland dihexadecyl-dimethyl ammonium chlorides in a weight ratio of 70:30, respectively, in isopropyl alcohol. The reaction was carried out in the presence of the mineral lubricating oil employed in the grease, employing stoichiometric amounts of the amine salts and bentonite on the basis of the measured base exchange capacity of the bentonite. A typical grease preparation was carried out in the following manner: 113 grams of the commercial amine salt mixture was mixed with 2,112. grams of a refined paraffinic residual oil having a gravity, API of 26.0, a Saybolt Universal viscosity at 100 F. of 977 seconds and a viscosity index of about 80, the mixture heated to 250 F. and circulated in a Manton-Gaulin homogenizer at 5000 pounds pressure di.f

3 4 ferential while 200 grams of bentonite and then 4.8 grams Table III of formamide were added. The circulation was continued for 45 minutes. The following table shows the yield and penetration at stability of the product thus obtained as compared with a grease prepared in the identical way except that 4.8 5 Additives Worked on Worked grams of water was added instead of the formamide. Unwmked Strokes Table I None Ltquid Composition, Wt. Percent, Calculated: 06% Formamlde 332 n 341 379 Organo clay 11.5 11.5 10 Sac;gratinchlori e 8g 3-3 1 Converted from size cone, }4 size worker used. g r n agiga As shown by the data given in the tables, very ma eri- Penetration, ASTMat 5p; ally improved yields are obtained by employing Sma l %i rgg l rei $3 533 amounts of formamide in greases thickened with polar penetration solids of various types, including such greases containing r -10,000 stro s 311 higher aliphatic amines and amide having a yield depress- As shown by the above table, a stable grease was obtained in satisfactory yield by employing 0.2 weight percent of formarnide in conjunction with the organo treated bentonite as the thickening agent. On the other hand, the same amount of water was ineffective to produce a stable grease structure in this composition. By the use of larger amounts of water, up to about 1 percent, substantial yield improvements were obtained in greases of this type, but these were still considerably lower than those obtained with equivalent or lower amounts of formarnide.

Table II below shows the efiect of formamide in improving the yield in a different solids thickened grease, and also shows its effect in offsetting the yield depressing effect of higher aliphatic amines and amides which were employed to improve the water resistant properties of the grease. The greases comprised 15.0 percent by weight of finely divided silica, having an average particle size of 0.022 micron and a surface area of 160-175 square meters per gram, in a refined naphthene base oil having a Say bolt Universal viscosity at 100 F. of about 310 seconds. The preparation was carried out by mixing together the solid thickener and additives with the lubricating oil at room temperature and finishing by milling in a Premier colloid mill with two passes at 0.002 inch clearance.

Table II Grease Composition, Percent:

Silica 15.0 15.0 15.0 Formamide l) 1.5 0.3 N,N-di- (beta by 0 0 1.0

droxyethyl) 12-hydroxysteararnide. Duomeen T 1 0 0 2.0--.. 2.0 0 0 Lubricating Oil 85.0 83.5 83.0... 81.5 84.0.-. 83.2 AS'EM Penetration at Unworked 331 317 400+-- 356 347-.-- 297 Worked60 strokes... 380 331 400 390 400+" 341 Worked100,000 400+ 315 381 345 strokes. Dynamic Water Resist- 100 100 Too 4 Toe ance Test, percent loss. soft soft for for test. test.

1 Commercial mixture of compounds having the formula RNHGflI NHi, where R is an alkyl group derived from tallow.

As shown by the above table, the use of a small amount of form-amide very materially increased the yield and stability of the silica thickened grease, and also offset the yield depressing effect of a higher aliphatic amine and amide, so that by the use of these additives with formamidc, silica thickened greases having good water resistance properties were obtained in satisfactory yields.

The following table shows the effect of formamide in a solids thickened grease of a still diiierent type. This was a grease comprising as the thickening agent percent by weight of finely divided zinc oxide, having an average particle size of 0.12 micron, in a refined naphthenic distillate oil having a viscosity at 100 F. of about 310 seconds. The preparation was carried out in the manner described for the silica thickened grease above.

ing effect. In addition, the greases containing formamide have greatly improved working stability, as shown by the smaller amount of change which occurred in the greases of the examples upon working 10,000 or 100,000 strokes in the ASTM worker test.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating grease consisting essentially of a major amount of lubricating oil, about 5-45 percent by weight of a finely divided polar solid having the property of forming gels with lubricating oils, selected from the class consisting of bentonites which have been surface treated with higher aliphatic amines, silica and oxides of zinc, magnesium and aluminum, and about 0.505.0 percent by weight of formamide, said finely divided polar solid being present in an amount sufficient to thicken the composition to a grease consistency.

2. A lubricating grease according to claim 1 wherein the formamide is present in an amount of 0.1-3.0 percent by weight.

3. A lubricating grease according to claim 1 wherein the said finely divided polar solid is bentonite which has been treated with a compound chosen from the class consisting of higher aliphatic amines and salts thereof.

4. A lubricating grease according to claim 1 wherein the said finely divided polar solid is silica.

5. A lubricating grease according to claim 1 wherein the said polar solid is zinc oxide.

6. A lubricating grease according to claim 1 wherein the said grease contains about 0.05- percent by weight, suificient to improve its water resistant properties, of a compound selected from the class consisting of higher aliphatic amines and amides.

7. A lubricating grease according to claim 6 wherein the said amides are alkanolamides of higher fatty acids.

8. A lubricating grease consisting essentially of a major amount of mineral lubricating oil, about 7-25 percent by weight, suflicient to thicken the composition to a grease consistency, of finely divided silica, about 0.1-3.0 percent by weight of formamide and about 05-50 percent by weight of a compound chosen from the group consisting of higher aliphatic amines and amides.

9. A lubricating grease according to claim 8 containing 0.5-5.0 percent by weight of N,N-di-(betahydroxyethyl)- IZ-hydroxystearamide.

10. A lubricating grease according to claim 8 containing 0.5-5.0 percent by weight of a compound having the formula RNHC H NH where R is an aliphatic hydrocarbon group containing lO-25 carbon atoms.

11. The method of grease preparation which comprises providing a mixture consisting essentially of a lubricating oil, about 545% by weight based on the weight of the mixture of a finely divided oil insoluble high melting solid having a measurable surface polarity and having the prop- 5 6 erty of forming gels in lubricating oils, and about 0.05 of formamide and shearing the said mixture until a grease 5% by weight of formamide, and subjecting the said mixconsistency is obtained.

cure to shearing until a grease consistency is obtained.

References Cited in the file of this patent 12. The method of grease preparation which comprises heating together a mixture of lubricating oil, a minor 5 UNITED STATES PATENTS amount of a compound chosen from the class consisting 2,592,863 Her 09L 26, 1954 of higher aliphatic amines and salts thereof, about 5-45% FOREIGN PATENTS by weight of bentonite and about ODS-5.0% by weight 735,711 Great Britain Aug 24, 55

. UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,986,517 May 30, 1961 Norman R. Odell et al.

it is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 35, for "O.505.0" read OO55,0

Signed and sealed this 17th day of October 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC

Claims

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF LUBRICATING OIL, ABOUT 5-45 PERCENT BY WEIGHT OF A FINELY DIVIDED POLAR SOLID HAVING THE PROPERTY OF FORMING GELS WITH LUBRICATING OILS, SELECTED FROM THE CLASS CONSISTING OF BENTONITES WHICH HAVE BEEN SURFACE TREATED WITH HIGHER ALIPHATIC AMINES, SILICA AND OXIDES OF ZINC, MAGNESIUM AND ALUMINUM, AND ABOUT 0.05-5.0 PERCENT BY WEIGHT OF FORMAMIDE, SAID FINELY DIVIDED POLAR SOLID BEING PRESENT IN AN AMOUNT SUFFICIENT TO THICKEN THE COMPOSITION TO A GREASE CONSISTENCY.