US2323789A - Lubricant composition - Google Patents

Description

Patented .iuiy 6, 1943 UN i an STATES Parent Wm LUBRICANT ooMrosrrroN Rolston L. Bond, Cranford, N. 3., assignor to Tide -Water Associated Oil Company, Bayonne, N. --a corporation of Delaware No Drawing. Application September 27, 1940,

Serial No. 358,662

invention relates to lubricationi concerned with enhancing the utilityand prolonging the useful life of lubricants, especiallypetroleum lubricating oils. Improved lubricating oils for internal combustion engine or other severe lubricant service constitute an important objective. Straight petroleum oils of suitable 'viscoslty fail to provide satisfactory lubrication in many services. Modern internal combustion engine operation frequently requires lubrication under severe conditions which tend to cause early de'-' terioration of ordinary lubricants resulting in ineifective lubrication and often in engine break-' encountered, for example, in automotive engines designed for high speed operation entailing high temperatures and high bearing pressures necessitating the use of special bearing surfaces such as those formed of cadmium-silver and like alloys. Coincidently, serious trouble results from susceptibility of such special alloy bearings to corrosion caused by the oil used to provide lubrication therefor. Further dimculties in many modern lubrication services arise from the known low film strength, or inability to provide efiective lubrication under severe conditions where high pressures between contacting moving surfaces are developed, of straight petroleum lubricants.

Accordingly, the present invention is directed generally at betterment of lubricants derived from petroleum whereby improved operating characteristics in one or more respects may be obtained. In one specific embodiment, the invention is particularly concerned with enhancing and prolonging the utility of lubricants (such as lubricating oils operating in internal combustion engines) which by reason of origin or degree of refining are desirable for effective lubrication under many conditions but exhibit pronounced tendencies toward deterioration.

To these and other ends, there is disclosed herein a class of organic compounds providing new additives useful for incorporation in petroleum lubricating oils, The lubricant of the invention comprises a viscous petroleum base stock, normally of high quality by conventional lubrication standards, -containing an improvement amount of an organic sulflte additive or inhibitor compound selected from the particular class described below. a

This class may be generally defined as alkyl or alkyl amine esters of sulfurous acid conformingto the general formula s=o RX wherein R designates an alkyl or substituted alkyl group; and X may be 0 or N(R). A convenient method for preparing such compounds {is to react, in suitable mola'l proportions, thionyl 1 5: chloride (SOClz) with aliphatic alcohol or secondary aliphatic amine.

In more specific grouping, compounds covered by the aforesaid general formula may be desig-, nated by the following sub-generic formulae r) R'O wherein the several R's represent the same or different aliphatic or substituted aliphatic residues, for example methyl, ethyl, propyl, butyl, amyl, etc., radicals.

Compounds in sub-group (1) may be formed by reacting two mols of an alkyl alcohol with one mol of thionyl chloride.

To form compounds in sub-group (2), it is convenient first to react one mol of an alkyl alcohol with one mol of thionyl chloride, and subsequently treat the reaction product with one mol of a secondary aliphatic amine.

For the preparation of sub-group (3) compounds, two mols of a secondary aliphatic. amine are reacted with one mol of thionyl chloride.

The method of preparing lubricant additives comprising compounds of the class disclosed herein forms no part of the present invention, the synthesis thereof having been adequately described in available technical literature and texts to reference may be had for instruction in the preparation of particular suitable members of the class.

It will be appreciated that organic sulfites of the type defined herein which are useful as lubricant additives for inhibitor or other service are those which are sufllciently oil soluble, substantially water insoluble and nonvolatile at service temperatures. These properties will govern the selection of desired active compounds.

One useful method of evaluating lubricating oils is that utilizing the familiar Underwood oxidation testing apparatus. This provides a measure of comparative oil deterioration as evidenced by sludge formation, acidity development and viscosity increase; and coincidently indicates the tendency of an oil to corrode sensitive bearing metal alloys. {is conducted for the results reported below, a single cadmium-silver half-bearing supported on a 2" x copper baille is mounted in the test chamber and lubricating oil maintained at 325 F. is sprayed continuously on the bearing and baiile for a period of hours. A 1500 c. c. sample of oil is used and is recirculated through the apparatus during the test period. The test 011 was a high quality Pennsylvania motor oil of S. A. E. 10 grade to which had been added 0.005% F8203 as iron naphthenate (an oil deterioration positive catalyst) to increase the severity of the test.

Using this test method the following results were obtained with and without an additive compound according to the invention. These results clearly demonstrate the effectiveness of an organic sulfite of the general class disclosed as an improvement agent for petroleum lubricants.

In the foregoing table, bearing loss is expressed as grams and is a measure of corrosion by the test oil. Naphtha' insoluble material is expressed as per cent of the used oil, neutralization number as milligrams KOH per gram sample of used oil, carbon residue as per cent of the used oil and viscosity increase as per cent of new oil viscosity at 210 F.; all of these characteristics being a measure of oil deteriortaion tendency.

It will be apparent from the foregoing test results that proportions as low as 0.5% of a composition according to the invention are markedly efiective in improving the quality and enhancing resistance to deterioration of lubricating oils.

The proportion used in the illustrative example is not of course limitative; nor will the same selected proportion of additive be used in every instance. Both the specific sulflte ester used according to the invention and the lubricating oil environment in which it serves will influence the amount of improvement agent added to the oil. Naturally. solubility will vary both as between different sulfite esters of the class described and as between diflerent lubricating oil stocks to which the inhibitors are added. Solubilizing agents may be used but are not contemplated as especially necessary.

Usually improvement in lubricating oils, particularly for resistance to oxidation or like motor oil service degradation, is obtained with proportions of additive of the order of 0.1% to 1.0% by weight based on the oil. This is well within the limit of solubility of compounds in the designated class. For some services larger proportions, for example 5% to 10% by weight of additive based on the oil, will be useful. As a general proposition the invention contemplates and encompasses in intended scope the use of the new additives in all lubricant improving proportions.

I claim:

1. Viscous mineral oil composition containing minor proportions of an oil soluble, water in soluble, sufficiently non-volatile alkyl amine ester of sulfurous acid active to enhance the lubricating value of said oil.

2. Viscous mineral oil composition containing minor proportions of an oil soluble. water insoluble, sufficiently non-volatile additive active to enhance the lubricating value of said oil, said additive comprising a halogen-free compound conforming to the general formula 1 wherein R is from the group consisting of alkyl and substituted alkyl radicals and X is from the group consisting of O or N(R).

3. Viscous mineral oil composition containing minor proportions of an oil soluble, water insoluble, sufllciently non-volatile halogen-free additive active to enhance the lubricating value of said oil, said additive comprising a reaction product of thionyl chloride with at least one member of the class consisting of aliphatic alcohols, substituted aliphatic alcohols, secondary aliphatic amines, and substituted secondary aliphatic amines.

4. Viscous mineral oil composition containing dibutyl sulfite.

ROLSTON L. BOND.