US3069357A

US3069357A - Synthetic lubricating composition

Info

Publication number: US3069357A
Application number: US803367A
Authority: US
Inventors: Ralph P Chesluk; Raymond B Tierney
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1959-04-01
Filing date: 1959-04-01
Publication date: 1962-12-18
Anticipated expiration: 1979-12-18

Description

United States Patent Ofifice 3,0fi9,357 Patented Dec. 18, 1962 3,069,357 SYNTHETIC LUBRICATING COMPOSITION Ralph P. Cheslulr, Fishkill, and Raymond B. Tierney,

Wappingers Falls, N.Y., assignors to Texaco Inc., a corporation of Delaware No Drawing. Filed Apr. 1, 1959, Ser. No. 803,367 Claims. (Cl. 252-464) This invention relates to synthetic lubricant compositions containing extreme pressure additives which do not promote corrosive properties of the composition toward bearing metals such as copper and lead. More particularly the invention relates to ester-type lubricating fluids containing additive amounts of metal halides complexed with sulfones and sulfoxides.

Lubricating requirements of high speed aircraft turbine engines make necessary the use of lubricants possessing high extreme pressure properties. Improved extreme pressure additives which do not degrade other lubricating properties are always in demand for these lubricants.

In accordance with the present invention, an improved lubricating composition comprises an ester base lubricating fluid containing an additive amount of the complexed reaction product of iron, cobalt or nickel chloride with a sulfone, disulfone or sulfoxide to increase the extreme pressure properties of the composition. The preferred reaction product is ferric chloride complexed with a disulfone. These reaction products are generally added to the lubricating fluid in amounts ranging from 0.05 to 2.0 (wt) percent and preferably from 0.1 to 1.0 (wt) percent.

Examples of complexed reaction products useful as E.P. additives for this invention include: ferric chloride-npropyl sulfone, ferric chloride-n-propyl disulfone, ferric chloride-butyl sulfoxide, ferric chloride-disulfone, of his (Z-ethylhexyl thiocarbityl) ether, ferric chloride-sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether, ferric chloridedisulfone of bis(3-thia-6-oxa-8-ethyldodecyl) ether, cobalt chloride-n-amyl disulfone, cobalt chloride-sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether, cobalt, chloridedisulfone of bis(3-thia-6-oxa-8-ethyldodecyl) ether, nickel chloride-n-propyl sulfone, nickel chloride-n-butyl sulfoxide, nickel chloride-disulfone of bis(2-ethylhexyl thiocarbityl) ether, nickel chloride-sulfcxide of bis(3-thia-6- oxa-8-ethyldodecyl) ether and nickel chloride-disulfone of bis(3-thia-6-oxa-8-ethy1 dodecyl) ether.

In general, aliphatic esters of aliphatic dicarboxylic acids are used as base fluids in the lubricants of this invention. The dicarboxylic acid component is usually an aliphatic dicarboxylic acid containing 6 to 12 carbon atoms but glutaric acid esters and succinc acid esters may also be used. From the standpoint of cost and availability, the preferred dibasic acids are adipic acid, 'sebacic acid and azelaic acid.

The aliphatic alcohols used to form the diesters usually contain at least 4 carbon atoms and may contain 20 or more carbon atoms. C to C alcohols are most commonly used. Ether alcohols, such as Cellosolve and Carbitol may also be used in the formation of the aliphatic diesters of organic dicarboxylic acids used as the lubricating base in the compositions of this invention.

Specific examples of the dialkyl esters of aliphatic dicarboxylic acids, which are the preferred base fluids for use in the lubricant composition of the invention, are as follows: di-isooctyl azelate, di-Z-ethylhexyl sebacate, di- 2-ethyl hexyl azelate, di-Z-ethylhexyl adipate, dilauryl azelate, di-sec-amyl sebacate, di-Z-ethylhexyl alkenylsuccinate, di-2-ethoxyethyl sebacate, di-2-(2'methoxyethoxy) ethyl sebacate, di-Z-(Zethylbutoxy) ethyl sebacate, di-Z- butoxyethyl azelate, di-2-(2'butoxyethoxy) ethyl alkenylsuccinate, etc.

In addition to the aliphatic dicarboxylic acid esters described above, polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a glycol and a monofunctionai compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in US. 2,628,974 to Robert T. Sanderson, issued February 17, 1953. Complex esters formed by reaction of a mixture containing specified amounts of 2-ethyl-l,3-hexanediol, sebacic acid and Z-ethylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and 2-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

Polyesters formed by reaction of a monocarboxylic acid and a glycol may also be used as the ester component. The acid component is usually an aliphatic acid containing at least 6 carbon atoms. The glycol component is advantageously a straight glycol such as 1,6-l1exanediol, but ether glycols, such as tetraethylene glycol, may also be used.

Specific examples of the diesters of glycols are the following: di-n-decanoate of 1,4-butanediol, di-Z-ethylhexanoate of 1,6-hexanediol, dilaurate of 1,4-hexanediol, dioctanoate of 1,5-pentanediol, dilaurate of tetraethylene glycol, dilaurate of triethylene glycol, dioctanoate of pentaethylene glycol.

Complex esters formed by reacting trimethylol alkanes with various mol ratios of dibasic acids and monobasic acids or alcohols is another example of polyesters useful for the base fluid of the lubricants of this invention.

The sulfur analogs of the above-described esters are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate, di-n-octyl thioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and Z-ethylhexyl mercaptan.

The finished lubricant composition of this invention normally contains other well known additives which act as V.I. improvers and anti-oxidants. For example, phenothiazine, which acts as an anti-oxidant and a methacrylate polymer, which acts as a V1. improver, thickener, and detergent, are usually included in the finished lubricants and are often necessary in order to meet rigid military requirements. Phenothiazine, which has the formula:

is a particularly effective anti-oxidant and anti-corrosive agent. It inhibits corrosion by preventing oxidation of the components of the lubricating composition to acidic bodies which are inherently corrosive. Phenothiazine is usually present in a concentration of 0.1 to 1.5 weight percent of the lubricant composition.

Various aromatic amines either alone or in combination are also known to have anti-oxidant properties and may at times be used in the present composition. For example, naphthylarnines, diphenylamines and phenylene a diamines in amounts up to about 2 percent by weight are very efiective.

Methacrylate polymers are well known V.I. improvers and pour point depressors. Polyester base lubricants, although they, per se, possess excellent V.l. and pour, usually require the presence of small concentrations of methacrylate polymers to meet the requirements of military specifications. These methacrylate polymers are usuaccess? ally copolymers of two or more esters of methacrylic acid and usually have a molecular weight between 500 and 20,000. The methacrylate esters have the following general formula:

wherein R is an aliphatic radical preferably ranging from butyl to stearyl.

Copolymers which find particular use as Vi improvers and pour point depressants are the following: a copolymer wherein R in the above formula comprises 20% lauryl, 40% octyl and 40% cetyl; a copolymer wherein R in the above formula is 50% stearyl and 50% lauryl; a copolymer wherein R in the above formula comprises 50% lauryl and 50% octyl.

=Methacrylate polymers are usually sold in the form of a concentrate comprising approximately 60 to 40% polymer in a carrier oil. For the lubricant compositions of this invention, it has been found advisable to use an ester-type carrier oil rather than the usual mineral base lubricating oil. The use of a methacrylate ester in an ester-type carrier oil has proven particularly effective in meeting the low temperature requirements of military specifications.

Methacrylate polymers can constitute 1 to 20 weight percent of the composition but ordinarily are used in a concentration between 1.5 and 10 weight percent.

In general the complexed products of this invention are conventionally formed by mixing or refluxing equal mols of the sulfone, disulfone or sulfoxide component with the metal halide component until the reaction is complete.

The following examples demonstrate the preparation of some of the complexed reaction products of this invention.

EXAMPLE I 450 g. of bis(3-thia-6-oxa-8-ethyldodecyl) ether and 300 ml. of acetic acid were placed into a 2 liter flask and heated to 90 C. 38 g. of 30 percent hydrogen peroxide were then added to the mixture over a 30 minute period. The 90 C. temperature was maintained for 40 minutes after which 38 g. of hydrogen peroxide in 40 ml. of acetic acid were added over a 30 minute period. Again after maintaining the same temperature for 40 minutes, 40 g. of hydrogen peroxide in 40 ml. of acetic acid were added over a 30 minute period. The resulting mixture was kept at a temperature of 95-100 C. for 2 /2 hours and then allowed to stand overnight. The mixture was then shaken with 2 liters of water to form an emulsion. The emulsion was ether extracted, washed with 1 liter of 5 percent sodium bicarbonate, and then water washed until neutral to Congo red. The ether was removed and toluene added for removal of water. The mixture was distilled off until the pot temperature reached 86 C./5 mm. 453 g. of a clear amber liquid fluid was obtained having a refractive index at 20 C. of 1.4798. The product, the sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether, in the amount of 96 g. and 115 g. of cobalt chloride in 500 ml. of benzene were added to a one-liter flask and refluxed for 6 hours. 41 ml. of water separated and the reaction mixture was blue in color. The mixture was allowed to stand over night and then filtered. 71 g. of solid material, be lieved to be 'CoCl was recovered and benzene was stripped from the filtrate. The product was dark blue, very viscous and weighed 95 g. Analysis showed 8.92 percent cobalt and 9.90 percent sulfur. This material, cobalt chloride-sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether complex was added to an estertype synthetic base fluid for testing. The test composition was as follows:

(Wt.) percen Di-Z-ethylhexyl sebacate 79.5 Copolymer of stearyl and lauryl methacrylate in di- Z-ethylhexyl sebacate (50% cone.) 20.0 Ferric chloride-sulfoxide complex 0.5

Tests on the above composition gave the following results:

The above results demonstrate that the synthetic lubricant composition of the invention are excellent in stability and resistance to oxidation and corrosion. This is particular.y evident with respect to copper which is an important bearing metal.

The following is another example of the preparation of a complexed reaction product of this invention:

EXAMPLE II 3 liters (2832 g.) of bis(3-thia-6-oxa-S-ethyldodecyl) ether and 750 ms. of 50% H were poured into a 12 liter, three neck flask. The mixture was heated to 70 C. by heating mantle and then a hot solution of 375 g. of KMnO dissolved in 3750 ml. of water was added at a rate so that the temperature was maintained between 7075 C. Addition required 3% hours and thereafter solid potassium permanganate was slowly added at temperatures between 70-75 C. When the brown color of the mixture became constant for 1 hour at 75 C. the temperature was raised to C. This was maintained for one hour and the color remained constant. The mixture was allowed to cool and 376 g. of solid KMnO was added. On standing an oil layer separated from an aqueous layer and the dark brown aqueous layer was extracted with 2500 mls. of ether. The ether was stripped and the oil was treated with toluene for removal of water. It was then filtered and allowed to stand. The oil layer was then treated with charcoal and filtered. The resulting product, the disulfone of bis(3-thia-6-oxa-8-ethyldodecyl) ether, weighed 2256 g., contained 11.9 percent oxygen, 11.84 percent sulfur, had a hydroxyl number of 23, and a neutralization number of 0.6.

200 g. of the above disulfone was placed in a 500 ml. flask and stirred. 40 g. of ferric chloride was added slowly at room temperature during the stirring temperature of the reaction mixture was raised to 65 C. for 1 hour and then allowed to cool to room temperature. The product was filtered and the filtrate weighed 235 g. 50 g. of this filtrate was slurried with 300 mls. of water at C. for 1 hour and then cooled to room temperature. An oil layer separated and the water layer was ex-- tracted with n-pentane. The pentane was stripped and. toluene added for water removal. The FeCl -disulfone. complex produced weighed 31 g.

The reaction products of this invention were tested for extreme pressure properties in the well-known Mean Hertz Load Test which briefly consists of applying the lubricant to three locked steel balls and a fourth steel ball which is made to rotate against the locked balls at predetermined pressures. The performance of the lubricant, as determined by known standards, is measured and is termed the Mean Hertz load for that particular lubricant composition. This test is more fully described in US. 2,600,058.

Data for various lubricant compositions, including those of the invention, in the Mean Hertz Load Test are set forth in the following table:

Table I MEAN HERTZ LOAD TEST Composition: M.H.L. value. Base fluid A 1 21 Base fluid A+0.5 (wt) percent of CoCl sulfoxide of bis (3-thia-6-oxa-8-ethyldodecyl) ether 2 Base fluid B 2 21 Base fluid B+0.5 (WL) percent dibutyl sulfone 22 Base fluid B+0.5 (WL) percent FeCl -n-propyl sulfone Base fluid 21 Base fluid C+1.0 (wt) percent Fecl -disulfone of bis (3-thia-6-oxa-8-ethyidodecyl) ether 52 1 Di2-ethy1hexy1 sebacate (wt) percent of 50 percent solution of the copolymer of lauryl and stearyl methacrylates in di-Z-ethyihexyl sebacate+0.5 twt.) percent phenothiazine. Di-2-et11ylhe. :y1 azelate+18 (Wt) percent of 40 percent solution of the polymer of butyl methacrylate in di-2-ethy1- hexyl sebacate+ 0.5 (wt) percent phenothiazine.

Di-2-etl1y1l1exyi aze1ate+0.5 (Wt) percent phenothiazine. From the above data, it is obvious that the complexed products of this invention are superior E.P. agents for ester-type synthetic lubricants. The superiority of the complexed sulfones and sulfoxides over the normal sulfones, such as the dibutyl sulfone of the table is also evident since the dibutyl sulfone does not increase the extreme pressure properties of the base fluid significantly.

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

We claim: 1. A synthetic lubricant consisting essentially of an ester base lubricating fluid and from 0.05 to 0.2 weight percent of the complex formed by the reaction of about 6 1 part by weight of a chloride of a metal selected from the group consisting of iron, cobalt and nickel with from about 0.8 to 5.0 parts by weight of a compound selected from the group consisting of sulfones, disulfones and sulfoxides, said amount being sufficient to incrase the extreme pressure property of the composition.

2. A synthetic lubricating composition consisting essentially of a major amount of aliphatic ester of an aliphatic dicarboxylic acid and from 0.05 to 0.2 weight percent of the complex formed by the reaction of about 1 part by Weight of a chloride of a metal selected from the group consisting of iron, cobalt and nickel with from about 0.8 to 5.0 parts by weight of a compound selected from the group consisting of sulfones, disulfones and sulfoxides.

3. A synthetic lubricating composition as described in claim 2 wherein the complex is formed by reaction of ferric chloride and n-propylsulfone.

4. A synthetic lubricating composition as described in claim 2 wherein the complex is formed by reaction of ferric chloride and the sulfoxide of his (3-thia-6-oxa-8 ethyldodecyl) ether.

5. A synthetic lubricating composition as described in claim 2 wherein the complex is formed by reaction of ferric chloride and the disulfone of his (3-thia-6-oxa-8- ethyldodecyl) ether.

References Cited in the file of this patent UNITED STATES PATENTS 2,199,944 Peski et al. May 7, 1940 2,257,969 Loane et al Oct. 7, 1941 2,318,629 Prutton May 11, 1943 2,645,613 Adelson et al July 14. 1953 OTHER REFERENCES Lub. Eng, August 1952, pp. 177-179. I. and E. Chem., April 1947, vol. 39, No. 4, pp. 494 and 495.

Claims

1. A SYNTHETIC LUBRICANT CONSISTING ESSENTIALLY OF AN ESTER BASE LUBRICATING FLUID AND FROM 0.05 TO 0.2 WEIGHT PERCENT OF THE COMPLEX FORMED BY THE REACTION OF ABOUT 1 PART BY WEIGHT OF A CHLORIDE OF A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT AND NICKEL WITH FROM ABOUT 0.8 TO 5.0 PARTS BY WEIGHT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFONES, DISULFONES AND SULFOXIDES, SAID AMOUNT BEING SUFFICIENT TO INCRASE THE EXTREME PRESSURE PROPERTY OF THE COMPOSITION.