US2450321A - Rust-inhibiting greases - Google Patents

Description

atenteii Sept.

RUST-INHIBITING GREASES Ernest 1:. White, Jackson Heightsyand Reuben Carl Robinson, NewYoi-k, N. it, assignors to Socony-Vacuum Oil Company, Incorporated, a

corporation of New York No Drawing. Application April 9, 1957, Serial No. 740A95 l- 14 Claims. (01. 252-42) 2 This invention relates to improved lubricating compounds contemplated for use as rust-precompositions and, more particularly, to rust-inventive additives in greases of this invention are hibiting grease compositions. substituted phenoxyatetraethoxy ethanols, sub- It is well known that moisture, even in the stituted naphthoxy tetraethoxy ethanols, substipresence of lubricants, has a tendency to cor- 5 tuted anthroxy tetraethoxy ethanols, substituted rode steel, iron, and other metal parts with which phen-anthroxy tetraethoxy ethanols, and the like, it comes in contact. Corrosion of this type is parwherein at least one of the. substituen-ts in the 'ticularly prevalent and troublesome in the opera aromatic nucleus is a group such as butyl, amyl, tion of steam turbines where steam or water is in hexyl, octyl, dodecyl, tetradecyl, hexadecyl, oleyl continual contact with almost all parts of the tur-- or other alkyl group containing up to 30 carbon bine system. As is readily apparent, corrosion atoms; a cycloaliphatic group, such as cyclohexyl, and rusting of .the metallic parts of such systems octyl-cyclohexyl, lauryl-cyclohexyl, cetyl-cycloand other similar precision-built machinery is to hexyl, butyl-cyclohexyl, etc.; bornyl, abietyl, be strictly avoided. It is highly desirable, theredecahydron-aph-thyl tetrahydro-abietyl, or other fore, to prepare lubricants which offersubstanterpenic radical or a naphthenic radical; phenyi, tial resistance to rust formation in the presence benzyl, phenylethyl, phenylisobutyl or other aryl of water. In the case of marine turbines, the or arylaliphatic hydrocarbon group. The sublubricant employed should also prevent rusting stituents above mentioned may have straight or in the presence of sea water. branched chains and the aromatic nucleus of the Greases employed for the lubrication of steam above defined compounds may have more than turbines and other machinery which is much in one substituent which may either be the same or contact with water have heretofore been treated a different group. In general, when more than with certain rust-preventive agents, such as meone substituent is present in the aromatic nucleus tallic sulfonates and the like, which have the of the above compounds, at least one of the subproperty of permitting the metallic surface to be '2 stituents will contain four or more carbon atoms; preferentially coated with lubricant instead of the remaining substituent or substituents may water, thus preventing or substantially reducing then optionally contain less than four carbon the actual contact of the Water with the metal atoms and be represented by methyl, ethyl,

surface and the ensuing rust formation. An obpropyl, isopropyl radicals, and the like.

jectionable feature resulting from the use of me- It has been found, as a general rule, that the tallic sulfonates and similar water soluble comdiand poly-substituted compounds of the type positions has been the tendency of such materials described above are more effective in inhibitin to render a grease, containing the same, waterrust formation when incorporated in greases than absorbent. This undesirable phenomena, in turn, the mono-substituted compounds. The use of the causes a change in structure of the grease and former type compounds accordingly represents a leads to the formation of an emulsion of the preferred embodiment of this invention. In pargrease and water, thereby thinning out the grease ticular, the substituted phenoxy tetraethoxy' and substantially reducing its lubricating emethanols are suitably employed as rust-preventive ciency. additives in the greases of the present invention.

It is an object of the present invention to pro- 40 Of the various su'bstituent groups, preference is vide-grease compositions which are free from the accorded those compounds containing alkyl subabove described emulsion-forming tendency and stituents.

which. at the same time, offer substantial resist- The above described compounds may be suitance to rust formation in the presence of water. ably prepared by condensing a phenolic compound The aforesaid object is accomplished in ac- 4,5 corresponding to the formula:

cordance with the present invention by the pro- Y R :H

vision of a grease containing a small amount of a compound characterized by the general formula: with a compound of the type;

Y-R-owrncmon-H n-(ocrncnmk where R is an aromatic nucleus of the benzene. in which X is a halogen atom, said condensation anthracene, phenanthrene, naphthalene or other taking place in the presence of an alkali to split condensed ring series, and Y is an aliphatic, cyout an alkali metal halide and thus yield the decloaliphatic, arylaliphatic or aryl group havingv at sired inhibitor. 3

least four carbon atoms. Representative of the The greases containing one or more of the aforesaid compounds are the alkali metal base reases. that is, grease compositions consisting basically of mineral oils in admixture with alkali metal soaps of fatty acids or with a sufficient proportion of such alkali metal soaps resent to iv to the greases the characteristics usually recognized as attributable to alkali base greases. These greases are usually prepared by heating a fat or a fatty acid, or a mixture thereof. with a mineral oil and thereafter heating the resultant mixture with caustic soda at elevated temperatures to obtain a substantially anhydrous soda soap grease. Lithium soap greasesare ordinarily made by charging a lithium soap to a grease kettle, adding minera1 oil, and heating at an elevated temperature in the range of about 380 to 440 F. with agitation to prepare a homogeneous composite which is .then withdrawn fromthe kettle and allowed to cool. The greases so prepared will generally have an alkali metal soap content of less than about 30 per cent of the final composition, and preferably between about 5 and about 20 per cent.

The mineral oil constituent of the greases contemplated herein may vary considerably in character and includes residual or distilled oils. Preference is accorded, however, to oils having a viscosity (S. U. V.) of 50-200 seconds at 100 F. The fat and fatty acids which may be employed are those generally found in alkali metal base greases. Examples of such saponifiable materials include. vegetable, animal and fish fatty oils; hydrogenated fatty materials thereof; high molecular weight organic acids, such as stearic acid and oleic acidrthe high molecular weight acids resulting from the oxidation of petroleum fractions; rosin and related products; high molecular weight naphthenic acids, sulfonic acids, etc.; and saponifiable waxes, such as beeswax, sperm oil, degras, and the like.

While the present invention contemplates the improvement of alkali metal base greases generally, it has been discovered that lithium base greases are rendered particularly effective as rustinhibiting compositions by incorporation therein of small amounts of the above described inhibiting compounds. Thus, a preferred embodiment of this invention is the provision of a rustinhibiting lithium base grease.

It has further been discovered, in accordance with this invention, that the inhibitors described hereinabove can be incorporated in the alkali metal greases during any stage of the manufacturing process before the grease is drawn from the kettle into containers to cool. The amount of inhibitor employed in the greases of the type described will normally be less than about 5 per cent of the final composition, the minimum amount to be used being about 0.1 per cent and the preferred amount between about 0.5 and about 2 per cent and, in' particular, an amount of the order of 0.75. per cent.

In addition to the rust-preventive agents set forth above, variousother materials may be added to the grease compositions of this invention, such as alcohols and other solvents, oxidation inhibitors, waxes, fillers, etc. Oxidation inhibitors which may be added to the grease include alkyl phosphites, phenyl alpha naphthylamine, tetramethyl diamino diphenyl methane, benzidine, etc. the production of a good grease in accordance with the present invention, are preferably employed to aid in prolonging the life of the grease and to inhibit oxidation thereof. The amount of Such anti-oxidants, while not essential to,

anti-oxidant employed may vary from about 0.001 per cent to about 1.0 per cent of the finished grease.

Various tests exist for measuring the tendency toward rust formation of lubricants. The greases of the present invention wereevaluated by the salt spray method prescribed in Naval Ordnance specification O. S. 1350, section F-3b, dated June 22, 1945. Briefly, this method consists of coating a clean, polished steel panel with a uniform thin film of grease to be tested. The amount of grease so applied is such that its total weight does not exceed 0.21 gram when applied to a panel of approximately 1"x3"x The panels so treated are allowed to stand in a dust-free atmosphere at room temperature for 24 hours and are then exposed to a 4 per cent salt spray at about 95 F. for a specified period of time. usually not less than 100 hours. The panels are then examined for rust formation.

The following greases and results of testing in accordance with the above described procedure are illustrative of those contemplated by the present invention:

Example I A slurry of 13 parts by weight of lithium stearate and 85.25 parts by weight of naphthenic oil having a viscosity (S. U. V.) of 60 second at F. was prepared in a grease kettle. The mixture was then fire-heated with agitation at a temperature in the range of 380-410" F. When the grease was in a molten state, one part by weight of phenyl alpha naphthylamine and 0.75 part by weight of octyl methyl phenoxy tetraethoxy ethanol were added. The composition was then thoroughly stirred to mix in the antioxidant and inhibitor. The resultant mixture was maintained in the above temperature range for 5-10 minutes with stirring. At the end of this time, the grease was drawn into pans and allowed to cool. The solid grease was then cut into cakes of the desired size and then milled in a grease mill to a smooth, buttery, homogeneous structure. This grease is hereinafter referred to as grease 1.

Example II A lithium base grease was prepared as in Example I, except that, as the rust-preventive agent, 0.75 part by weight of octyl phenoxy tetraethoxy ethanol were incorporated in the grease. The grease so obtained is hereinafter referred to as grease II.

Example In A grease, consisting of 15 parts by weight of a sodium salt of a hydrogenated fish oil and 84.25 parts by weight of a naphthenic oil having a viscosity (S. U. V.) of 100 seconds at 100 F., was prepared in a conventional manner in a steam-heated kettle. The fatty material was melted in a portion of the mineral oil, and the caustic soda, as a water solution, was added while 'agitat'ing. The resulting mixture was dehydrated sultant grease is hereinafter referred to as grease Example IV A soda base grease was prepared as in Exemple III, except that, as the rust preventive agent, 0.75 part by weight of octyl phenoxy tetraethoxy ethanol were incorporated in the grease.

The grease so obtained is hereinafter referred to I as grease IV.

The above prepared greases were tested in accordance with the salt spray test described hereinabove and the following results were obtained:

Uninhibited lithium A series of extended tests on lithium base greases I and II showed that panels coated with 'grease I could be exposed for a period of 250- 300 hours to the salt spray at a temperature of 95 F. before rusting occurred. Similarly, panels coated with grease II could be exposed for a period of 150-200 hours before rusting took place. A conventional lithium base grease containing only soap, oil, and anti-oxidant, when tested under identical conditions, was found to allow rusting to occur in less than 20 hours.

These results indicate a very substantial and useful increase in inst-inhibitin properties of alkali greases, particularly lithium base greases, and considerably widen the field to which such greases may be applied, rendering them capable of use in a great number of applications in the presence of Water, wherein they have formerly not been capable of use with a particularly high degree of efiiciency.

. It is to be further noted that the rust-inhibiting compounds of this invention are water-insoluble and while imparting rust-proofing properties to the grease, do not detract from the natural water insolubiiity of lithium grease itself. The maximum water absorption of a conventional lithium base grease, prepared according to the procedure set forth in Example I, but without the incorporation of octyl methyl phenoxy tetraethoxy ethanol, was found to be about 20 per cent when-tested in accordance with the water-absorption test prescribed in Naval Ordnance specification 0. S.-13,50, section F-3h, dated June 22, 1945. With the addition of 0.75 per cent of this compound to afford over 100 hours salt spray protection, the water absorption of the grease was still only 20 per cent. When a conventional rust preventive, such as sodium sulfonate, was employed, it was found necessary to use 2 per cent of this material to secure the same salt spray protection as attained with 0.75 per cent of an inhibitor of this invention. Moreover, it was found that a grease containing sodium sulfonate absorbed over 200 per cent by weight of water and became a thin emulsion when subjected to the aforementioned waterabsorption test. The grease containing the rustinhibiting compounds of this invention showed no change in structure when brought into contact with water.

We claim:

1. An alkali metal rust-inhibiting grease comprising a major proportion of a mineral oil, an alkali metal soap present in sumcient propor- 6 tion to thicken said oil to a grease consistency, and between about 0.5 and about 2 per cent by weight or a. compound having the general formula:

YRO(CH2CH2O) s-H where R represents an aromatic nucleus and Y is a member selected from the group consisting of aliphatic, cycloaliphatlc, arylaliphatic and aryl hydrocarbon radicals having at least four carbon atoms.

2. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral 011, an alkali metal soap present in suflicient proportion to thicken said 011 to a grease consistency, and between about 0.1 and about 5 per cent by weight of a compound.

having the general formula: I

Y-R,O(CH:CH2Q) s--H where R represents an aromatic nucleus and Y is a member selected from the group consisting of aliphatic, cycloaliphatic, arylaliphatic and aryl hydrocarbon radicals having at least four carbon atoms.

3. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral oil, a lithium soap present in suflicient proportion to thicken said oil to a grease consistency, and between about 0.1 and about 5 per cent by weight of a compound having the general formula;

hydrocarbon radicals having at least four carbon atoms.

4. A lubricating grease composition characterized by resistance to to rust formation, comprising a major proportion of a mineral oil, a sodium soap present in suflicient proportion to thicken said oil to a grease consistency, and between about 0.1 and about 5 per cent by weight of a compound having the general formula:

where R represents an aromatic nucleus and Y is a member selected from the group consisting of aliphatic, cycloaliphatic, arylaliphatic and aryl hydrocarbon radicals having at least four carbon atoms.

5. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral oil, a lithium soap present in sufiicient proportion to thicken said oil, and between about 0.5 and 2 per cent by weight of a compound having the general formula:

where R represents an aromatic nucleus and Y is a member selected from the group consisting of aliphatic, cycloaliphatic, arylaliphatic and aryl hydrocarbon radicals having at least four carbon atoms.

6. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral oil, an alkali metal soap present in suflicient proportion to thicken said oil to a grease consistency, and between about 0.1 and about 5 per cent by weight.

of an alkyl-substituted phenoxy tetraethoxy ethanol, the alkyl substituent of which contains at least four carbon atoms.

7. A lubricating grease composition cl'aracterized by resistance to rust formation, comprising a major proportion of a mineral oil, a lithium soap present in suificient proportion to thicken said oil to a grease consistency, and between about 0.1 and about percent by weight of an alkylsubstituted phenoxy tetraethoxy ethanol, the alkyl substituent 01 which contains at least four carbon atoms.

8. A lubricating grease composition character ized by resistance to rustformation, comprising a major proportion of a mineral oil, a lithium soap present in sufficient proportion to thicken said oil to a grease consistency and between about 0.5 and about 2 per cent by'welsht of an alkylsubstituted phenoxy tetraethoxy ethanol," the alkyl substituent of which contains at least four carbon atoms. I

9. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral oil, an alkali metal soap present in sumcient proportion to thicken said oil to a grease consistency. and between about 0.1 and about 5 per cent by weight of octyi methyl phenoxy tetraethoxy ethanol.

10. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of a mineral oil, an alkali metal soap present in sufficient proportion to thicken said oil to a grease consistency, and between about 0.1 and about 5 per cent by weight of octyl phenoxy tetraethoxy ethanol.

11. A lubricating grease composition characterized by resistance to rust formation, comprising a major proportion of mineral oil, a lithium about 0.1 and about 5 per cent by weight of octyl methyl phenoxy tetraethoxy ethanol.

12. A lubricating grease composition characterized by resistance to rust formation, comprising a. major proportion of mineral oil, a lithium soap present in sufllcient proportion to thicken said oil to a grease consistency, and between about 0.1 and about 5 per cent of octyl phenoxy tetraethoxy ethanol.

13. An alkali metal rust-inhibiting grease formed by compounding together a major proportion of a mineral oil, from 5 to per cent of a high molecular weight fatty acid soap of an alkali metal and from 0.5 to 2 per cent by weight of an alkyl-substituted phenoxy tetraethoxy ethanol, the alkyl substituent containing at least soap present in suflicient proportion to thicken said oil to a grease consistency, and between four carbon atoms.

14. A lithium base rust-inhibiting grease formed by compounding together a major proportion of a mineral oil. from 5 to 20 per cent of a high molecular weight fatty acid soap of lithium and from 0.5 to 2 per cent of an alkyl-substituted phenoxy tetraethoxy ethanol, theaikyl substituent containing at least four carbon atoms.

ERNEST T. WHITE. R. CARL ROBINSON.

REFERENCES CITED The following references are of record in the file of this patent:

. UNITED STATES PATENTS Number Name Date 2,233,381 De Groote et a1. Feb. 25, 1941 2,361,043 McCieary Oct. 24, 1944