US2854408A - Lubricating grease compositions containing aliphatic sulfonic acid soap - Google Patents

Description

United States Patet LUBRICATING GREASE COMPOSITIONS CON- TAINING ALIPHATIC SULFONIC ACID SOAP William H. Brugmann, Jr., Milltown, Jeffrey H. Bartlett, Westfield, and Arnold J. Morway, Clarktownship, Union County, N. J., and Frederick Knoth, Jr., Palembang, Sumatra, Indonesia, assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application November 7, 1955 Serial No. 545,512

4 Claims. (Cl. 252-33) This invention relates to novel lubricating grease compositions. Particularly, the invention relates to lubricating grease compositions prepared by thickening a lubricating oil with a soap of an aliphatic sulfonic acid.

The present application is a continuation-impart of copending application Serial No. 264,684, filed January 2, 1952, now abandoned by the present inventors.

It has been found and forms the object of this invention that lubricating grease compositions may be prepared by thickening a lubricating oil to a grease consistency with an essentially oil-insoluble soap of a long chain aliphatic sulfonic acid having from about 10 to 20 carbon atoms in the aliphatic portion thereof. The grease compositions so prepared have excellent smooth structures and high dropping points;

The olefins produced from the cracking of petroleum Wax or petrolatum in general possess relatively long straight chains in which the olefinic group is near the end or the molecule. The large percentage of alpha olefins are obtained by the cracking of wax or petrolatum with some beta olefins also being formed. By the sulfonation of these olefins a product is obtained which has a sulfonic acid group near the end of a relatively long straight chain. Other sources of olefins for the preparation of these long chain sulfonates are polymerized olefins from Fischer synthesis, polyethylenes, polypropylenes, polybutenes, and other polymeric olefins which give long straight chained molecules with relatively little branching.

Various methods have been described in the literature for the preparation of sulfonic acids from olefins. Such methods include the conversion of the olefin to a halide and then treating with sodium sulfite. The olefinic halide may also be converted to a mercaptan and the mercaptan oxidized to the sulfonic acid. Treatment of olefinic materials with S or ClSO H in the form of complexes with ether, dioxane, and the like has proved very success- 111 in the production of hydroxy sulfonic acids or chlorosulfonic acids. The hydroxy sulfonic acids may be dehydrated to yield alkene sulfonic acids. Similar products may be obtained by heating the chloro-sulfonic acids in which hydrochloric acid is split off. The straight sulfonic acids, and the chloro acids are operable in the manufacture of the grease compositions of this invention. However, it is preferred to use the unsubstituted aliphatic sulfonic acids.

In general, the lubricating grease compositions of this invention are prepared by forming the metallic soap of the long chain aliphatic sulfonic acid and dispersing said 2 soap in a lubricating oil. This is simply accomplished by heating the mixture of the mineral oil and the sulfonate with agitation to a temperature above the melting point of the sulfonate and then allowing the heated mass to cool without stirring.

Additional properties may be incorporated intothe lubricating greases of this invention by admixing with minor amounts of various other additive materials. For instance, high temperature properties are obtained by codispersing the metal sulfonates with low molecular weight acid salts. Such materials as the metallic salts of acetic acid, furoic acid, and the like may be added.

It is also within the concept of this invention to form a grease composition by thickening a lubricating oil with a mixture of the metallic soap' of a long chain sulfonic acid and any of the soaps ordinarily used in grease-making, for example, high molecular weight substantiallysaturated fattyacid soaps. The incorporation of some additional conventional soap adds to the smoothness of the grease as well as improving the dropping point.

As was stated above, the long chain aliphatic sulfonic material contemplated by this invention contains from 10 to 20 carbon atoms per molecule. Although it is preferred that the aliphatic portion of the sulfonic acid be of straight chain configuration, some slight branching is allowable. Especially preferred and contemplated in the preferred embodiment of this invention are those aliphatic sulfonic acids having from 10 to 20 carbon atoms in a straight chain configuration.

Soaps of the sulfonic acids, as described above, are prepared from alkalior alkaline-earth metals commonly used in the preparation of soaps from the conventional high molecular weight fatty acids. These include sodium, potassium, lithium, strontium, barium, calcium, and so forth. Sodium is preferable and is used in the preferred embodiment. These'metals are also employed to form the aforementioned salts of low molecular weight acids and soaps of conventional high molecular weight fatty acids.

The lubricating oil which serves as a base of the lubricating grease composition of this invention may be any of the lubricating oils known to the art, either natural occurring or synthetic. Mineral lubricating oils, preferred in the instant invention, having viscosities within the range of from about 35 to about 300 S. U. S. at 210 F. may be used. Those synthetic lubricating oils such as esters of dibasic acids (e. g. di-Z-ethyl-hexyl sebacate), esters of monobasic acids, ethers, glycols, glycol ethers, glycol esters, complex esters, or mixtures of the above may be used. Small amounts of petroleum resins may also be employed.

As Was mentioned above, it is within the concept of this invention to form a grease composition by dispersing in an oil a combination of the metallic soap of a long.

. Patented Sept. 30, wasv as complex soapthickeners'in combination with the high molecular weight soaps. It is particularly preferred to incorporate in the sulfonic acid soap thickened lubricants such materials as the metal salts of low molecular weight acids exemplified by acetic acid. Monocarboxylic acids containing 1 to 6 carbon atoms per molecule are pre ferred. Acetic acid is particularly preferred.

It has been found advantageous to thicken lubricating oil with from about 5% to 30% by weight based on the weight of the total composition of the metallic soap of the aliphatic sulfonic acid; Inth'ose instances wherein a combination of a conventional soap. and the sulfonate are used, from 10 to 90% (preferably '50 to 90%) of the sulfonate is combined withabout 90 to 10% (preferably 10 to 50%) by weight of; the conventional soap. This combination ofsoaps will be employed in a concentration of about 5 to 30% byweight; based on total composition. A metal salt ofza low molecular weight acidic material may also be combined in order to obtain the advantages as outlined above, in concentrations of from 0.5 to 15.0% by weight, preferably 2.0 to 10.0% by weight based on the total composition. Generally, it is preferred to use the metal salt of low molecular weight acidic material approximately in a 1:1 to 5:1 mol ratio pressure and 170 C. at 0.7 mm. pressure was segregated This cracked petrolatum fraction had for sulfonation. a bromine number of 64.3 c. e. q. Br g.

The sulfonation was carried out in a 3-liter'3 necked flask fitted with a stirrer, thermometer and dropping funnel. To the flask was charged 300 g. of anhydrous ethyl ether. After cooling the ether to 5 C., 306 g. of CISO H was added during 5 minutes at 5 C. to C. which resulted in forming a ClSO H ether complex. While maintaining the ClSO H ether complex at C. to +2 C., 630 g. of cracked petrolatum (considered as approximately C H with molecular weight of 252) was added during 20 minutes. After all the olefin had been added the resulting mixture was stirred for an additional 1 /2 hours during which the temperature was allowed to rise to 25 C. The reaction product was then neutralized with 25% NaOH solution after which 99% isopropyl alcohol was added so as to produce a 50% alcohol solution in which the sulfonate was dissolved. This solution was then desalted with Na CO followed by separation of the supernatant layer. Water was added to the supernatant layer to produce approximately 50% isopropyl alcohol containing the sulfonate. The isopropyl alcohol solution was then extracted 5 times with petroleum ether to remove any unreacted olefin or other hydrocarbons. Evaporation of the petroleum ether yielded 243 g. of unreacted hydrocarbons.

The alcoholic solution containing the sulfonate was drum dried yielding abrownish colored powder. This sodium sulfonate had a chlorine content of 4.91%.

7 Example I 150 g. of the sodium soap of the long chain sulfonate prepared as described above were dispersed in 250 g. of an acid-treated Mid-Continent distillate having a visosity at 210 F. of about 40 S. U. S. hereinafter referred to as oil A. The mixture was heated to 100 F. with agitation. There was then added an aqueous solution of 100 g. of sodium acetate and the mixture heated to 225 F. at which temperature the soap became dehydrated.

Penetration, 77" F., mm./10:

Unworked 200 Worked (60 strokes) 240 Dropping point, F 380 Water solubility soluble A. S. T. lVL-bearing lubrication test, hours (bearing operating at 3600 R. P. M. and 250 F 204 Excellent lubricantno tendency of grease to leak from bearing due to fluidization.

Example II 10.00% sodium soap of long chain sulfonate (as above) 5.00% hydrogenated fish oil acids 0.75% sodium hydroxide 84.25% oil A A of the mineral oil and all of the fish oil acids were mixed in a fire-heated grease kettle and heated to F. with stirring. When the acid was completely melted an aqueous solution of the sodium hydroxide was added. When the acid neutralization or soap forming reaction was complete, the sodium sulfonate was added to the mixture and the mass heated to 225 F. for dehydration. When dehydration was complete the balance of the mineral oil was added and the temperature raised to 260 F. It was then allowed to cool to 200 F. with stirring and the result was an excellent smooth product having the following inspections:

Penetration, 77 F., mm./l0:

Unworked 275 Worked (60 strokes) 275 Dropping point, F 354' Example III A portion of the grease as prepared in Example II above was admixed with an aqueous solution of sodium acetate so. that the resulting composition contained 2% of sodium acetate. The solution of sodium acetate was dispersed in the grease and the mass was heated to 500' F. It was then allowed to cool and further homogenized by working. The pertinent inspections of this grease sample are set out below:

Penetration, 77 F., mm./10:

Unworked 225 Worked (60 strokes) 265 Dropping point, P 425 Example IV 20.0% sodium soap of long chain sulfonate (as above) to the standard grease inspections this grease compositron gave the following results:

Penetration, 77 F., mm./

Unworked 300 Worked (60 strokes) 310 Dropping point, F. 320

Lubrication (AFBMA-NLGI Test) satisfactorily lubricates a 204 hearing at 80-90 F. satisfactorily lubricates a 204 bearing at 150 F.

To summarize briefly, this invention relates to a lubricating grease composition prepared by thickening a lubricating oil by the addition of small amounts of an essentially oil-insoluble metalic salt of along chain aliphatic sulfonic acid having from 10 to carbon atoms in the aliphatic portion thereof. From about 5% to about 30% of the sulfonate has been found operable although from about 8% to about 20% is preferred. The grease compositions may also be prepared by dispersing in a mineral oil a combination of the long chain sulfonate and the conventional grease forming soaps. It is also contemplated to combine with these grease combinations the salts of low molecular weight materials exemplified by sodium acetate, sodium furoate, and the like.

What is claimed is:

1. A lubricating grease composition comprising a major proportion of a mineral lubricating oil thickened to a grease consistency with 5 to 30 wt. of an oil-insoluble metal soap of a substantially straight chain aliphatic sulfonic acid containing from 10 to 20 carbon atoms per molecule in the aliphatic portion thereof said aliphatic sulfonic acid being the sole sulfonic acid present.

2. A lubricating grease composition comprising a major by weight of an oil-insoluble metal soap of a long chain aliphatic sulfonic acid having from 10 to 20 carbon atoms in the aliphatic portion thereof of substantially straight chain configuration said aliphatic sulfonic acid being the sole sulfonic acid present, and about 0.5 to 15.0% by weight of a metal salt of low molecular weight monocarboxylic acid, said metal being selected from the group consisting of alkali metals and alkaline earth metals.

3. A lubricating grease composition comprising a major proportion of a mineral lubricating oil thickened to a grease consistency with from 5% to 30% by weight, based on the weight of the total composition, of a combination of an oil-insoluble metal soap of a long chain aliphatic sulfonic acid having from 10 to 20 carbon atoms per molecule and a metal soap of a high molecular weight substantially saturated fatty acid said aliphatic sulfonic acid being the sole sulfonic acid present and, said combination consisting of about 10 to of the soap of said sulfonic acid and about 90% to 10% of the soap of said fatty acid, said metal being selected from the group consisting of alkali metals and alkaline earth metals.

4. A composition according to claim 3 wherein said grease composition contains combined therein from 0.5% to 15.0% by weight of a metal salt of a low molecular weight monocarboxylic acid, said metal being selected from the group consisting of alkali metals and alkaline earth metals.

References Cited in the file of this patent UNITED STATESPATENTS 1,871,941 Arveson Aug. 16, 1932 2,394,790 Liehe Feb. 12, 1946 2,535,101 Sproule et al. Dec. 26, 1950 2,540,534 Kolfenbach et al. Feb. 6, 1951

Claims (1)

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH 5 TO 30 WT. % OF AN OIL-INSOLUBLE METAL SOAP OF A SUBSTANTIALLY STRAIGHT CHAIN ALIPHATIC SULFONIC ACID CONTAINING FROM 10 TO 20 CARBON ATOMS PER MOLECULE IN THE ALIPHATIC PORTION THEREOF SAID ALIPHATIC SULFONIC ACID BEING THE SOLE SULFONIC ACID PERCENT.