US2959545A - Lubricating oil composition having high dispersancy - Google Patents

Description

2,959,545 LUBRICATING OIL COMPOSITION HAVING HIGH DISPERSANCY Harvey E. Alford, Amherst, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of 'Ohio No Drawing. Filed Dec. 31, 1956, Ser. No. 631,507

1 Claim. (Cl. 252-332) This invention relates to a combination of lubricating oil additives having exceptional dispersancy and, more particularly, to lubricating oil compositions comprising an alkaline sulfonate detergent and magnesium naphthenate.

For satisfactory performance, a motor oil should contain a dispersant to keep the insoluble materials which accumulate in the oil in suspension. In the absence of a dispersant, sludge particles agglomerate, plugging the oil lines and screens and causing undesirable deposits to separate out on the engine parts. i

In accordance with the invention, lubricating oils having an unusually high degree of dispersancy are obtained by employing in combination an alkaline sulfonate detergent and magnesium naphthenate. Neither of these additives by itself is fully satisfactory as a dispersant. Magnesium naphthenate alone is not a dispersant at all. However, the two together give a powerful synergistic effect.

The preferred alkaline sulfonate detergent is a basic barium sulfonate which is prepared from petroleum sulfonic acids having a molecular weight of about 220 to 250 by neutralization with barium oxide or hydroxide. This is mixed in the proportion of to 30 parts by weight (p.b.w.) with 2 to 10 p.b.w. of barium carbonate.

Very small amounts of the additives of the invention will give a marked improvement in dispersancy. The magnesium naphthenate is present in the oil in an amount within the range from 1% to 7%, and the basic barium petroleum sulfonate in an amount from 0.5 to 3%.

The additives of the invention can be used to improve the dispersancy of any petroleum hydrocarbon oil of lubricating viscosity. The S.A.E. viscosities for lubricating oils range from No. 10 to No. 70. Oils having S.A.E. Nos. 10 to 40 have a viscosity within the range from 90 to 255 SSU at 130 F., and those oils having S.A.E. Nos. 40 to 70 have a viscosity within the range from 80 to 150 SSU at 210 F. The acid-treated and solvent-extracted oils are equally useful in the compositions of the invention. The oils can be blended from suitable bright stocks and finished neutral oils of light and heavy viscosities. It is impossible here to give a complete description of the various methods used in the preparation of lubricating oils, but reference is made to the text by Georgi, entitled Motor Oils and Engine Lubrication, published by Reinhold Publishing Corporation, New York (1950), chapter V, wherein the various types of lubricating oils are discussed fully. Any of the oils mentioned therein can be employed in the composition of the invention.

The composition of the invention is prepared simply by mixing the additives either singly or together with the oil, at room temperature. The additives are soluble or dispersible in the oil, and disperse therein instantaneously. No solvents are required.

The following example represents, in the opinion of the inventor, the best embodiment of his invention.

nited States. Patent 2 O Patented Nov. 8,

Example A group of lubricating oil compositions were prepared, using a lubricating oil blend of 72.5 p.b. volume {solventextracted neutral thermal distillate having a viscosity of 300 SSU at 100 F., and 27.5 p.b. volume of a solventextracted bright stock having a viscosity of 78 SSU at 210 F.

(1) One lubricating oil composition was made up containing 5.44% magnesium naphthenate to givethe oil an alkaline No. of 12. The magnesium naphthenate was prepared by direct precipitation from a solution of sodium naphthenate in water, using one equivalent of magnesium chloride per equivalent of sodium naphthenate.

(2) Another was prepared containing 1 /2% basic barium petroleum sulfonate. This was a barium petroleum sulfonate prepared from petroleum sulfonic acids having a molecular weight of 235 in an amount of 17.8 parts by weight (p.b.w.) mixed with 3.5 p.b.w. of barium carbonate.

(3) and (4) Additional lubricating compositions were prepared containing both additives in the amounts indicated in the table, in each instance, with an amount of magnesium naphthenate to give the same alkaline number. Each of the compositions then was evaluated for dispersancy.

The dispersancy test is a measure of the ability of the oil to hold carbon black dispersed. The oil to be tested is made up as a 5% solution thereof in benzene, and 100 ml. of the solution is placed in a glass stoppered graduate. Carbon black in increments of 0.2 gm. is added to the solution, which is then shaken for fifteen seconds and permitted to stand for five minutes in front of a light source and the contents observed for a break point. This point is seen as a thin upper layer of completely transparent liquid containing no carbon black particles. If no break point is observed, additional increments of carbon black are added until there is a break point. The largest amount of carbon black which does not produce a break point is recorded as the result of the test. The test has been calibrated against various additive concentrations of dispersant additives in oil and is a measure of the dispersant or detergent properties of an oil.

The results are shown in the following table:

The synergistic effect of the magnesium naphthenate in combination with the barium sulfonate is evident from the table. The rating of 6.8 to 8.0 in Nos. 3 and 4 is far superior to the ratings of either of these additives by themselves (Nos. 1 and 2), which range from 3.6 to 0, and these superior values are obtained using less of each additive.

Other modifications will be obvious to one skilled in the art and these are intended to be included within the scope of the following claims:

I claim:

A mineral lubricating, oil composition exhibiting improved dispersancy consisting of from to 98.5% mineral oil and from 1.5 to 10% of an additive containing from 0.5 to 3 parts by weight basic barium petroleum sulfonate and from 1 to 7 parts by weight magnesium 2,415,353

naphthenate. 2,560,202 2,606,872

References Cited in the file of this patent UNITED STATES PATENTS 5 2,228,500 Bergstrom 13111.14, 1941 2,322,307 Neely et a1 -JLJune 22, 1943 4 Johnson et a1. Feb. 4, 1947 Zimmer et a1. July 10, 1951 Gasser et a1 Aug. 12, 1952 OTHER REFERENCES Motor Oils and Engine Lubrication, Georgi, Reinhold Pub. Co., New York (1950), pp. 169-176.