US2744870A - Lubricating compositions - Google Patents

Description

LUBRICATING coMPosiTroNs Cornelis Stillebroer, Delft, and Johan Leonard van der Minne, Amsterdam, Netherlands, assignors to Shell Development Company, New York, N. Y., a corporation of Delaware No Drawing. Application November 15, 1954, Serial No. 469,035

Claims priority, application Netherlands November 24, 1953 7 Claims. (Cl. 252-336) This invention relates to water-in-oil emulsions suitable for lubricating engines, particularly low speed diesel engines operating on high sulfur fuels.

Although it is known in the art that emulsions are useful as coolants and lubricants in metal working operations and as rust and corrosion inhibitors, their use as engine lubricants is limited. Under engine operating conditions, emulsions generally lack desired lubricity, causing wear and corrosion.

It has now been discovered that engines can be lubricated safely and efficiently by using a water-in-oil emulsion consisting essentially of from about to about 40% (preferably between 10% and about 30%) of water and from about 95% to about 60% (preferably between about 90% and about 70%) of a lubricating oil, said emulsion also containing, in the aqueous phase of the emulsion, a water-soluble salt of a divalent metal in an amount of at least 0.25 gram mols per liter, based on the aqueous phase, and preferably at least 0.5 gram mols per liter, and even higher, e. g., 2.5 gram mols per liter.

The cationic portion of the salt must be a divalent metal such as the alkaline earth metals, including calcium, barium, strontium, magnesium, as well as zinc, cadmium, nickel, lead, copper and iron; the preferred metals are calcium, barium, strontium and magnesium. The anionic portion of the salt is selected from anions of particular classes of inorganic and organic acidic compounds. Generally, these anionic radicals are such that with the above metals (cationic) they form water-soluble salts. Of the inorganic acidic compounds, the preferred ones are the weaker inorganic acids. Of the organic acidic compounds the preferred ones are: the lower fatty acids, e. g., formic, acetic and propionic acids; substituted lower fatty acids, such as hydroxy-, ketoand amino-acetic, propionic and butyric acids; polycarboxylic acids having not more than 10 carbons in the molecule, such as oxalic, maleic, and succinic acids; as well as aromatic acids. such as salicylic acid, mandelic acid, anthranilic acid, phthalic acid, and mixtures thereof. Specific examples of salts suitable for use in Water-in-oil emulsion lubricants of this invention includes the zinc, calcium, barium and magnesium nitrites, nitrates, chromates, sulfates, formates, acetates, propionates, aminoacetates, alpha-aminopropionates, glycol- 4 ates, oxalates, succinates, salicylates, phthalates, mandelates, anthranilates, and mixtures thereof.

The water-in-oil emulsions are generally prepared by incorporating one or more emulsifiers. Any emulsifier may be used which is suitable for emulsifying an aqueous phase in an oil phase, provided no harmful substances are formed from the emulsifier during the combustion process in the engine. Suitable emulsifiers are esters of polyhydric alcohols, such as the monoesters of glycerol with higher fatty acids, e. g., glycerol mono-oleate, glycerol mono-stea'rate, glycerol mono-ricinoleate, diethylene glycol mono-laurate, diethylene glycol mono-oleate, diethylene glycol mono-stearate and sorbitan mono-oleate; as

well as alkylene oxide derivatives of such partial esters such as reaction products of sorbitan mono-oleate and alkylene oxides, such as ethylene oxide; polyvalent metal salts of fatty acids, napthenic acids or organic sulfonic acids or resin acids; such as Ca, Ba, Zn and Al stearate, oleate, naphthenate, petroleum sulfonate and abietate; lanolin, oxidized vegetable oils and lecithin. A combination of two or more emulsifiers may also be used. Especially stable emulsions are obtained by the combined use of a polyvalent metal salt, e. g., a basic calcium salt of an oil-soluble petroleum-sulfonic acid, and a polyvalent metal salt, e. g., a basic calcium salt of an aromatic hydroxycarboxylic acid substituted by one or more alkyl groups with 12 or more carbon atoms, e. g., hexadecylsalicylic acid.

The water-in-oil emulsions may be prepared in a simple way by adding the aqueous salt solution to the oil containing the emulsifier(s), after which the mixture is stirred and preferably further homogenized, e. g., by passing the emulsion through a gear pump. By means of the latter treatment the average size of the particules dispersed in the emulsion can be considerably decreased, particularly to a size of 2 microns or less.

The lubricating oil used to form the water-in-oil emulsion of this invention can be any natural or synthetic hydrocarbonaceous oil having lubricating properties. Thus, the base may be a hydrocarbon oil of wide viscosity range, e. g., SUS at 100 F. to SUS at 210 F. The hydrocarbon oils may be blended with fixed oils such as castor oil, lard oil and the like, and/or with synthetic lubricants such as polymerized olefins, organic esters of polybasic organic and inorganic acids, e. g., di- Z-ethylhexyl sebacate, dioctyl phthalate, trioctyl phosphate; polymeric tetrahydrofuran; polyalkyl silicone polymers, e. g., dimethyl silicone polymer and the like.

Representative mineral lubricating oils which have been utilized in evaluating the utility of the present additives had the following specifications:

I II

Gravity, API-" Pour Point, F Flash, COO, F

Viscosity, SUS at 210 F.

Min. 26.5.

Min. 24.5.

Viscosity Index Water-in-oil emulsions of this invention are particularmally used in marine installations. Corrosion, Wear and fouling of such engines is aggravated because contaminants such as dirt, water and deterioration products from cheap grades of fuel (high in sulfur content) normally used to operate such equipment, can easily enter the lubrication system.

A cheap grade of hydrocarbon fuel containing substantial amounts of naturally occurring sulfur is used in low speed diesel engines because of economy and because it has been observed that sulfur-containing petroleum fuels have enhanced ignition properties. However, these advantages are countered by the corrosive nature of such fuels which results in excessive Wear.

By the expression high sulfur fuels as used herein is meant those fuels which contain sulfur, either in the free or combined state, to the extent of from about 0.1% to about 5.0% by weight and preferably between 0.5% and 3.5%, calculated as elemental sulfur, though even more sulfur may be present, and include petroleum fuel oil or various distillate and residual oils and the like.

Various means have been tried to overcome the detrimental effects of high sulfur fuels on engine operations. Thus, the Chandler patent, U. S. 2,673,145 proposes to add to high sulfur fuels various metallic inorganic salts in order to reduce the corrosive effects caused by the presenceofsulfur in the fuel. Although thismethod iseifec tive, it sufiers from certain disadvantages in its practical application. However, it has been found that engine efficiency can beincr eased 5' to'50 times'over theifilhandler method or similar methods by lubricatingengines operatingz on high sulfur fuels with water-in-oil emulsions .of this invention.

The invention will be further illustrated by the following examples.

A'number of'comparative: tests were. carried out in a 20 horsepower diesel two-stroke engine. The engine was run'atta speed of 600'revolutionsaminute.

'In eachof the tests the fuel was a gas oil with a sulfur content of 1% by weight, calculated'as elementalsulfur. A lubricating oil distillate with a viscosity of 42-centistoke at 60 *C., extracted according to the Edeleanu process, wasused as-the lubricating oil base in-each of the tests. In order to prepare the water-in-oil emulsions, glycerol inono-oleate was added to this lubricating oil as anemulsifier in a quantity of 2% by weight, calculated on the oil, after which an aqueous salt solution was added t'o theoil in a quantity of parts-by weight to 100 parts by weightof the lubricating oil containing the'emulsifier. After the emulsification had been efiected by stirring, the-emulsion 'was passed twice through a gear pump. Thus, by using various salts, diiferent water-in-oil-emulsions were obtained which were used for lubricating the cylindcr'in'the-diesel two-stroke engine referred to.

In 'each test the engine was run for 8 hours, after which it was inspected. Two successive tests with the lubricating oil base and two successive tests with a waterin-oil emulsion were carried out alternately.

The effect .of the various water-in-oil emulsions examined, as compared with the lubricating oil base,'was measured by determining the decrease in weight of the piston rings. This decrease in weight is a measure of the wear. The wear occurring with the use of the various water-in-oil emulsions is expressed as a percentage of the wear occurring when the lubrication is effected with the lubricating oil base as such, i. e., the latter wear is arbitrarily put at 100.

The results of the tests are shown in the following Table I. In this connection it should be further observed that with the use of lead acetate its aqueous solution was mixed with the lubricating oilbase in a quantityof parts by weight (instead of 10 parts by weight, as in the other cases) to 100 parts by weight of the lubricating oil base containing the emulsifier.

Table l gonceitr'ii Type. of saltin the emulsifier Ion 0 5a r so u ion rs sum or i t 3,3 g Fi t R ind meal/1 piston 0! piston ring rings Lead acetate... 0. 56 85 80 Zincacetate 1. 13 80 6O Magnesium acetate. 1. 13 55 60 Barium acetate.. 1. 13 50 Calcium acetate 1. 13 .40 Calcium oi-mate... 1. 13 55 Calcium nitrate. 1. 13 65' 55 Calcium nitrite .1. 13 45 Magnesium sulfate 1.13 55 6O Magnesium chlorid 1. 13 r 90 60 Sodium acetate. .2. 25 ,110 Aluminum acetate 0. 350 300 Aluminum chloride.. 0. 7 .600 500 IBOSPhOIiC acid.

13 rea Acetic acid 1. 13 135 Sulfuric acid 1-13 130 Potassium chroma-to. 1. 13 120 170 Hydrochloricacid. .1. 13 110. 105 Calcium nitrite. 0. 1 120 with the use of water-in-oil emulsions of which the aqueous phase contains no salt, or a-sodium or'potassium critical minimum value poor results areobtained. 'Reference ismade to lines 8 and 20 in Table I.

In another test a two-stroke 350 H. P. marinediesel engine operating at a speed of 250 revolutionsa minute was lubricated with an emulsion of this invention. and the results were as follows:

The motor fuel used was a bunker oil with a sulfur content of 3.2% by weight, calculated as. elemental sulfur. This fuel had a ConradsonCarbon-number of 11%.

As the emulsion, a water-in-oil emulsion was used, 70% byweight of which consisted of the oil base containing the emulsifier and 30% by weight of an aqueous 25 per cent calcium acetate solution. The oil base was'the same as-that used in Example 1. The emulsifier was a combination of a basic calcium'salt of .an oil-soluble petroleum-'sulfonic acid with a mixture of basic calcium compounds of'salicylic acids substituted by a straightchain alkylgroup having 14-18 carbon atoms. Each of the two components of the mixture of emulsifiers .was

used'ina quantity corresponding to 0.05% by weight .of

Ca, calculated on the oil base.

The efiect of the use of the watcr-in-oil emulsion, as compared to the oil base as such in lubricating the cylinder was determined ina manner similar to that of the previous example by'measuringthe loss in weight of the firstpiston ring and that of'the remaining piston rings, while at the same time ther'ouling of the cylinder wall was determined. For this purpose, a test was carried out with the water-in-" oil emulsion and a test with the oil base as such. The duration 'of each test was 17 2'h0urs.

With the use of the emulsion of the aqueous calcium acetate solution in the oil base it was foundthat the loss in weight of the first'piston ring was only 25% of the loss inweight'which occurred in usingthe oil base as such, while the loss in weight of the remaining piston rings. withthe use of the emulsion was only 12% of theloss in. weight occurring withthe use of the oil baseas. such. With the useof the emulsion the wear of the cylinder wall was only 10% of the wear which occurred with-the use of the oil base. In-this case the engine was operatedfor 400 hours.

With the use of the water-in-oil .emulsion there was also only slight fouling-of the cylinder wall. Moreover, the slight deposits .in the cylinder space were brittle in structure, and easily removed whereas with lubricating oil fouling on cylinder wall was .excessiveand .diflieult to remove.

I.During the-test the emulsion was found to remainstable in theilubricator. 1

Similar engine results can be'obtained using water-inoil'emulsionsof this invention as the lubricant for engines, operating on fuels containing from 1% to 3% sulfur in which the aqueous phase of the emulsion contains from- .about 0.5 to about '2.5 gram mols per liter of calcium,

tially of a water-in-oil emulsion consisting essentially of from 5% to 40% by weight of water and from 60% to 95% of a mineral lubricating oil, said water phase of the emulsion containing in solution at least 0.25 gram mols per liter of a water-soluble salt of a divalent metal.

2. A lubricating composition for lubrication of internal combustion engines operating with high sulfur hydrocarbon fuels, said lubricating composition consisting essentially of a water-in-oil emulsion consisting essentially of from 5% to 40% by weight of water and from 60% to 95% of a mineral lubricating oil, said water phase of the emulsion containing in solution from 0.5 to 2.5 gram mols per liter of a water-soluble alkaline earth metal salt.

3. The composition of claim 2 wherein the salt is calcium acetate.

References Cited in the file of this patent UNITED STATES PATENTS Lazar Feb. 11, 1941 Brown June 29, 1942

Claims (1)

1. A LUBRICATING COMPOSITION FOR LUBRICATION OF INTERNAL COMBUSTION ENGINES OPERATING WITH HIGH SULFUR HYDROCARBON FUELS, SAID LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A WATER-IN-OIL EMULSION CONSISTING ESSENTIALLY OF FROM 5% TO 40% BY WEIGHT OF WATER AND FROM 60% TO 95% OF A MINERAL LUBRICATING OIL, SAID PHASE OF THE EMULSION CONTAINING IN SOLUTION AT LEAST 0.25 GRAM MOLS PER LITER OF A WATER-SOLUBLE SALT OF A DIVALENT METAL.