US2417826A - Lubricating composition - Google Patents

Description

Patented Mar. 25, 1947 LRICATING COMPOSITION William A. Jones, Ponca City, Continental Oil Company, corporation of Delaware kla., assignor to Ponca City, Okla., a

Serial No. 57 9,319

8 Claims.

This application relates to application No. 466,945, filed November 25, 1942, now pending before the Patent Oflice. This invention relates to lubricating compositions adapted for use under service conditions involving high temperature and severe oxidation conditions.

In order to provide satisfactory lubrication of engine parts of engine operating under severe conditions of high temperature and high power output, it has been found necessary to use highly refined mineral oil lubricants. These highly refined mineral oil lubricants, usually obtained by solvent treating, have a reduced tendency to change in viscosity with temperature changes and to form oxidation products insoluble in the oil while in service.

Some of the difiiculties which have been encountered in their use, however. are their tendency to oxidize to form oil soluble organic acids which cause corrosion on the metal parts of the en ine, particularly the sensitive bearing materials commonly used in heavy-duty service. These specific materials when exposed to engine parts at hi h temperature form condensation products which result in lacquer-like products which interfere with the proper operation of the en ine.

A further undesirable feature of these hi hly refined lubr catin oils is their inab lity to carry in su ension extraneous material introduced into the crankcase from some outside source, such as soot and lead from the combustion chamber and dirt and dust from the atmosphere. This causes the collection of deposits in various portions of the engine wh ch prevents its proper operation. Because of these conditions a large number of addit on a ents have been incorporated in the blends of highly refined mineral oil in order to alleviate these difiiculties.

One class of these addition agents is materials contain n phosphorus or sulfur or both. These materials tend to preci itate or remove from solutlon in the oil. soluble metals resulting from the corrosion of the engine parts. The highly catalytic efiect of these metals in accelerating oil oxidation is thus removed. These materials, also, react with the exposed surfaces of the engine to form thin coatings of material less readily attacked by the organic acids resulting from oil oxidation.

Another type of addition agent commonly used in highly refined lubricating oils intended for heavy duty service is intended to prevent the formation of deposits of oil insoluble material in the various parts of the engine. longing to this class remove and prevent the formation of lacquer deposits, maintain the various oil insoluble materials in a colloidal state or as very small particles. Thus the oil insoluble materials are held in suspension in the lubricat- Materials being oil rather than being permitted to deposit on the metallic parts of the engine. The compounds commonly blended with the lubricating oil for this purpose are oil soluble-metal containing compounds.

The usual procedure in attempting to alleviate these various difiiculties consists of blending with a highly refined lubricating oil a mixture of these different types of additives. The active element in each of these additives is usually incorporated in an organic compound in order to increase the oil solubility. These various organic compounds are substantially all less stable to oxidation than the highly refined lubricating oil with which they are blended. The additive material itself thus becomes the source of objectionable oxidation products. The degree to which these addition agents detract from the stability of the lubricating blend varies with the amount and stability to oxidation of the organic compounds employed.

My invention resides in the discovery that all of these beneficial effects can be realized by blending with the highly refined lubricating oil a small but effective quantity of metal tetrathiophosphate substituted with wax olefin, one to five per cent is usually sufiicient. These wax olefin substituted metal tetrathiophosphates are extremely stable to oxidation and high temperature and contain the minimum of organic material necessary to secure oil solubility. Compounds used in the practice of this invention are Of the types MvM'wM"zR1 (Ps4)e, MZUM IRl/(PSQ) 2, MIRMPSQE in which M, M, and M are any of the metals, aluminum, antimony, barium, cadmium, calcium, cobalt, copper, iron, lead, lithium, magnesium, manganese, mercury, nickel, sodium, tin and zinc. R is a wax olefin group. Each of "22, w, 1 and "2 is a small whole number from one to five inclusive.

The method of preparation of the wax olefin consists of chlorinating a substantially oil free parafiin wax of low melting point and containing from 18 to 24 carbon atoms per molecule to a chlorine content of 8 to 12 per cent. This is done by dispersing bubbles of chlorine gas in the melted wax at a temperature of approximately 150 F. until the desired degree of chlorination is achieved. This is determined by the increase in Weight of the wax. This will result in a mixture of unchlorinated wax, monochlor wax and polychlor wax. Since the greater the degree of chlorination the lower will be the melting point of the various wax components, this mixture may be easily separated to substantially pure components by the sweating process. fraction is preferred for the production of wax olefin. The monochlor wax thus obtained is dehalogenated by mixing with it one-tenth of its weight of lime and heating one to five hours at temperatures betwen 200 F. and 500 F. This The monochlor 7 heating period also removes the hydrogen chloride so that the resulting olefin is substantially free from bot chlorinated wax and hydrogen chloride.

A number of the metal tetrathiophosphates are difiicult to prepare by the conventional procedure of heating the metal sulfides and phosphorus pentasulfide together. It has been found, however, that all of them are quite readily prepared by heating a mixture. of the metal sulfide and phosphorus pentasulfide in molten sulfur as a solvent. Since one atom of sulfur is required for each molecule of wax olefin in the: formation of wax olefin substituted metal tetrathiophosphate, this amount of sulfur is used as a solvent in the preparation of the intermediate metal tetrathiophosphate so that no separation isnecessary. An example of the preparation of one: of these materials is as follows: 18 parts by weight of calcium sulfide, 56 parts by weight of phosphorus pentasulfide and 16 parts by weight of sulfur were mixed and placed in a container tightly covered to exclude air. This mixture was fused one and one-half hours at 550 F. The mixture was then cooled and pulverized. This pulverized material Was then mixed with 209 parts by weight of wax olefin and the mixture heated with constant stirring for one hour at 390 F. This product was oil soluble and contained 7.2 per cent ash. A thirty minute copper strip test at 300 F. of a 2.5 per cent blend of this material in lubricating oil indicated that the material contained no uncombined sulfur.

The choice of metal used in this composition will depend on the type of service for which the lubricant is intended. For service which requires a high degree of detergency and a relatively mild control of oil oxidation and corrosion characteristics, such as is found in Diesel and Caterpillar engine operation, the preferred metal is one of the alkali metals or one of the alkaline earth group. For service. which requires more oxidation and corrosion control and less detergency, such as gasoline engines in heavy-duty service, the preferred metal constituent is tin or lead. For types of service which produce excessive bearing corrosion, the metallic element chosen should be copper. For types of service requiring both detergency and oil oxidation control approximately equally the choice of metal should be zinc. In a like manner each of the other metals listed are valuable for specific service conditions.

The quantity of this material which should be blended with the lubricant will depend upon the type of service for which the lubricant is intended and also upon the character of the mineral oil from which the lubricating composition is made. A mineral oil which has been subjected to a more severe refining process will require the addition of a larger quantity than a less severely refined oil. In general, quantities greater than 20% will not be required, usually 10% or even being satisfactory for compositions requiring substantial amounts of this material. Concentrations of as low as .01% will be found effective for certain purposes.

In addition to the wax [olefin which has been referred to above, I may employ any long-chain hydrocarbon of petroleum origin, 1. e., as a starting material I may employ any normally liquid fraction of petroleum, although paramn wax is the preferable material. The process of manu-e 4 facture explained above is applicable when using any unsaturated hydrocarbon.

Having thus described my invention I claim:

-1. A lubricating composition comprising a. mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the productof reaction at an elevated temperature of an unsaturated hydrocarbon and the material derived by fusing together a metal sulfide, a phosphorus sulfide, and elemental sulfur.

2. A lubricating composition comprising a mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the product of reaction at an elevated temperature of an unsaturated hydrocarbon and the material derived by fusing together a metal sulfide, phosphorus pentasulphide and elemental sulfur.

3. A lubricating composition comprising a mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the product of reaction at an elevated temperature of an unsaturated hydrocarbon derived from paraffin wax and the material derived by fusing together a metal sulfide, a phosphorus sulfide, and elemental sulfur.

4; A lubricating composition comprising a mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the product of reaction at an elevated temperature of an unsaturated hydrocarbon derived by halogenation and de-halogenation of paraffin wax and the material derived by fusing together a metal sulfide, a phosphorus sulfide, and elemental sulfur.

5. A lubrication composition comprising a mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the product of reaction at an elevated temperature of an unsaturated hydrocarbon derived from paraffinwax and the material derived by fusing together a metal sulfide, phosphorus pentasulfide, and elemental sulfur.

6. A lubricating composition comprising a mineral oil of lubricating viscosity normally tending to oxidize in use, having incorporated therein from about 1% to about 5% of the product of reaction at an elevated temperature of an unsaturated hydrocarbon derived from paraflin wax and the material derived by fusing together calcium sulfide, phosphorus pentasulfide, and elemental sulfur.

'7. A composition in accordance with claim 1 in which the metal sulfide is a copper sulfide.

8. A composition in accordance with claim 1 in which the metal sulfide is a barium sulfide.

WILLIAM A. JONES.

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

UNITED STATES PATENTS Rutherford Aug. 19, 1941