US2658871A - Lubricating composition - Google Patents

Description

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Patented Nov. 10, 1953 2,658,871 LUBRICATING COMPOSITION Paul V. Smith, Jr., Westfield, and James B. McPherson, Jr., Roselle, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application September 3, 1949, Serial No. 114,066

4 Claims.

This invention relates to lubricants having a high degree of oiliness, and more particularly to a lubricating composition which contains combined therein an ester of phosphoric acid to impart oiliness and film strength thereto. It is especially directed toward a lubricating composition which contains an oxo alcohol ester of a phosphoric acid.

In the lubricant art, considerable progress has been realized in recent years in the production of lubricants characterized by one or more specific properties and adapted for particular uses. In the main, this progress can be attributed to two developments: the first, new refining procedures, and the second, addition agents capable of imparting particular properties to available lubricants. Thus, viscosity index improvers and pour depressants are added to automotive lubricants to render the lubricants more adaptable to wide changes in temperature conditions, while other agents are added to improve the load carrying properties of a lubricant which is to be employed, for example, under extreme pressure conditions.

Certain machine elements, such as the hypoid gears commercially used in automotive vehicles, may be subjected at times to extremely heavy pressures of the order of hundreds of thousands of pounds per square inch. Under these conditions, if the film of lubricating oil separating the opposed elements fails, as it is likely to do under such pressure, the surfaces'contact each other directly with resultant seizure or excessive wear and early failure. To combat this deficiency in lubricating oils, a group of compounds known as extreme pressure additives has been developed. Extreme pressure additives contain active sulfur, phosphorus, chlorine or the like which react with the metal surfaces at the high temperatures generated by friction when machine elements operate at extremely high pressures. The presence of reactive chlorine and the like in a lubricating oil is detrimental to some extent in that it subjects the metallic elements lubricated to corrosive action. There is, accordingly, no advantage but, on the contrary, severe disadvantage to using extreme pressure lubricants where they are not essential.

A wide intermediate area lies between lubrication requirements; between those (1) requiring an extreme pressure lubricant and (2) those that may be met satisfactorily with straight run mineral oils. In this area an oil is required having a high film strength but which does not require extreme pressure action. It is toward the requirements of this intermediate area that the lubricating composition of this invention is directed. 7

It has been known in the lubricating art that the esters of phosphoric acid make very good extreme pressure additives for lubricating oils. For

example, Benning in U. S. Patent 2,167,867

teaches that an oil composition containing the alkyl or aryl esters of phosphoric acid is a good lubricant for cadmium-silver bearings. In U. S. Patent 2,252,133 Morway et al. teach that a valuable metal fabricating oil may be made by slightly sulfurizing an oil and incorporating therein an aliphatic or an aryl ester of phosphoric acid. Downing et al., in U. S. Patents 2,285,853-4 teach the improvement of lubricants by the addition of aryl or aliphatic esters of phosphoric acid. Knutson et al. in U. S. Patent 2,340,331 teach the combination of various organic derivatives of inorganic oxy-acids with a lubricant to improve the extreme pressure properties thereof.

It has recently been discovered that the esters of phosphoric acid made from oxo alcohols have excellent potency as oiliness or film-strengthening agents for lubricating oils. These oxo alcohol esters of phosphoric acid are made by treating the oxo alcohol with phosphorus oxychloride under suitable conditions. The various oxo alcohols are made by the so-called oxo synthesis process. This process may be described as the catalytic reaction of mono-olefins with carbon monoxide and hydrogen at a temperature of about 300 to 350 F. and under a pressure of about 3000 pounds per square inch to form an aldehyde, and the subsequent hydrogenation of the aldehyde to form a primary alcohol. The process was first developed in Germany and was first described in this country in U. S. Patent 2,327,066, issued to Roelen in 1943. Depending upon the starting olefin, various alcohols may be synthesized by this process. For example, a C7 frac tion isolated from the product of the polymerization of propylene or a mixture of C3 and C4 olefins, may be subjected to the oxo process and the resulting Ca oxo alcohol will be found to include a number of isomers having, on the average, two alkyl side groups along a carbon chain 4 to 6 carbon atoms in length.

Heretofore, it has been proposed to separate out a pure oxo alcohol from the crude product of the oxo process to form the phosphoric acid ester to combine with a lubricating oil. This procedure necessitates an expensive and time consuming fractionating process which makes it undesirable from an economic standpoint.

It has now been found that when the crude oxo product is used as an esterifying agent, a more effective additive is formed than when the purified x0 alcohol is used. Thus a double advantage is gained; a more effective agent is obtained and an expensive fraotionating process is eliminated.

Accordingly, this invention has as its primary object the formation of a superior lubricant by incorporating into a mineral base lubricating oil the desired amount of an ester of phosphoric acid obtained by reacting phosphorusoxychloride with the crude product of an oxo'reaction.

Although in its preferred embodiment the invention contemplates the use of a-crude Cc -.oxo alcohol, it is to be understood, of course, thatany of the oxo alcohols in their crude state may be used without departing from the concept of the invention. For example, a crude C9 cut, a crude 'Gu-"Cm fraction, a crude'C12-1s' fraction, or a -'crude-C13 44 out of alcohols made by the oxo "process'maybe used.

The process by which the crude phosphateis prepared is asfollows:

Crude 'Cc oxo alcohol, containing an amine -suchaspyridine, dimethyl amine, diethyl amine, etc" is treated with POC13, at a temperature *ranging'from about -10'to about +10 C. The

amine is present to tie up the released hydro chloric acid and can be regenerated and used again. -The mixture is refluxed several hours,

given below:

Hydroxy .0.011 centiequivalent/gm. Acid 0.012 centiequivalent/gm.

(this corresponds-to 3.8 .wt. percent calculated as the .diphosphate).

.Acetal 0.006 centiequivalent/gm. .Carbonyl 0.004 centiequivalent/gm. :HzO 0.0 centiequivalent/gm.

Bromine No"v -.0.l8 .centiequivalent/gm. Ash 5.21 centiequivalent/gm.

-All of these impurities are higher boiling than the-pure Cc 0X0 phosphate.

Various concentrations of the crude ester'o'f phosphoric acid in a solvent extracted coastal 'distilla'te having a viscosity at 210 F. of 45 S. U. -S.-.were prepared and tested in the 4-ball testing 'machine. This machine is designed to test lubri- 'cants under conditions of ressure to determine their film strength characteristics. The machine is so constructed that one steel ball contacts and rotates upon three stationary steel balls ofidentical physical properties. The lubricant being tested is placed upon the contacting surfaces and the desired load is applied upon the'single rotating ball. Wear scars appearing upon the three stationery balls are measured and :averaged, their diameters being a function of the film strength of the lubricant undergoing the test. The results-of the tests on materials pre- 'istic is particularly advantageous.

tions per minute. allow for free air circulation. Air, which spuripared in accordance with the concept of this invention are given in Table I below:

TABLE I 4-ball test machine data WcanScanDiametermm: (30min. test at 20-Kg. Load) Additive percent in Oil A Comml Gomml Pure Crude Agt. A 2 Agt. B 3 Ester Ester Solvent extracted coastal distillate having a viscosity at 210 F. 0M5 S. U. S.

' Tricresyl phosphate type.

Fatty acid ester typev .It will be noted from a study of Table I above that outstanding results are obtained when using the product of this invention, the wear scars showing a decided improvement over both'the "pure ester and-the commercial additives. These results are vparticularly outstanding since the 'I-Iertz inelastic compression of the balls of the testing machine is about 0.24 mm. under a 20 kg. load. It can readily be seen-that withthe additive of this invention'the wearispractically eliminated.

.Although the commercial additiveA shows wear scars only slightly greater than those of the crude ester, a very'favorable economic'advantage exists in theproduot of this invention,

"and since an expensive fractional distillation procedure is eliminated the products "prepared according to this invention are prepared ,at'a

great reduction in cost over the pure ester.

Although the additive material of thisinvention is preferably employed in -a mineralbase lubricating oil, it is operable to improve the-oili- .ness or film strength of any lubricating oil,

either natural or synthetic. Itmay be combined with the base stock in amounts varying ,from

0.5 to 10%, 0.5 to 3.0% ordinarily sufiicing'to obtain the desired improvement.

.The crude Cc oxo phosphate .is'also very useful as an additive for spindieoils in'whioh service its excellent film strength imparting character- A typical spindle oil was prepared using the orudeCBoXO phosphate, pure Cs oxo phosphate and the commercialadditive A, described inTablejI, on'the following formulation:

.600 gramsofa solvent extracted .R-hodessa :dis-

.tillate having aviscosity of210 F. of ell S.-,U.?S.

0.1% of a commercial-oxidationinhibitor. 0.075% of a. commercial detergent inhibitor.

10% of oiliness agent.

These prepared spindle oils were subjeoted'to "the Staeger'life test,'well known to the lubricating art, which is designed-to measure-the oxidation of-a lubricant under typical operating ,conditions. An oven maintained at a oonstanttemperature of C. is'equipped with'an aluminum shelf which is motordriven at from 5 to 6 revolu- The shelf contains "holes to 5 standard size copper strip (40 x 70 x 1 mm.) is placed in the sample, the copper strip serving as a catalyst for oxidation. At various stages of the test period, samples of the test oil are removed and a neutralization number obtained by the ASTM Dl88-27T method, the acidity of the sample increasing in direct ratio to the amount of oxidation. The Staeger life of a lubricant is defined as being the number of hours in the test oven necessary to raise the neutralization number 0.20. The results of the Staeger life test on the above spindle oil formulation are given in Table II below:

Examination of the test data given above shows a Staeger Life on the spindle oil containing the product of this invention of slightly less than 320 hours. This compares very favorably with the value of less than 235 hours for the spindle oil containing the commercial additive A, or a life of approx. 290 hours for the spindle oil having the pure Ca oxo phosphate incorporated therein.

To recapitulate briefly, the present invention comprises the discovery that a greatly improved film strengthening or oiliness agent for incorporation into mineral based lubricating oils to improve the film strength or oily characteristics thereof may be prepared by reacting the crude Cs alcohol mixture resulting when polymers of propylene and butene are submitted to the x0 process with phosphoric oxychloride in the presence of an amine derivative followed by water washing and stripping to 180 to 190 C. 5-6 mm. vacuum.

It is to be understood that the lubricating composition of this invention may include other additives for imparting desirable characteristics to lubricating oils, such as extreme pressure additives, corrosion inhibitors, anti-oxidants, viscosity index improvers, pour depressors and the like.

What is claimed is:

l. A lubricating composition which comprises a major amount of a mineral lubricating oil having combined therewith about 0.5 to 3.0% by Weight of an ester of phosphoric acid, said ester being formed by reacting phosphorus oxychloride with the crude product obtained by subjecting a copolymer of propylene and butylene to the 0x0 process.

2. A lubricating composition which comprises a major amount of a mineral lubricating oil having combined therewith about 0.5 to 3.0% by weight of an ester of phosphoric acid, said ester being formed by reacting phosphorus oxychloride with the crude product obtained by subjecting a copolymer of propylene and butylene to the action of carbon monoxide and hydrogen in the presence of a cobalt catalyst at a temperature in the range of from 300 to 350 F. at a pressure of about 3000 pounds per square inch gauge and hydrogenating the aldehydes so formed.

3. A lubricating composition which comprises a major amount of a mineral base lubricating oil with about 0.5 to 10% by weight of a phosphoric acid ester of a crude Cs oxo alcohol.

4. A lubricating composition which comprises a major amount of a mineral base lubricating oil with about 0.5 to 10% by weight of an unpurified product obtained by reacting phosphorus oxychloride with a crude Cs oxo alcohol in the resence of pyridine.

PAUL V. SMITH, JR. JAMES B. MCPHERSON, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,005,619 Graves June 18, 1935 2,080,299 Benning et a1 May 11, 1937 2,285,853 Downing June 9, 1942 2,389,513 Kemp Nov. 20, 1945

Claims (1)

1. A LUBRICATING COMPOSITION WHICH COMPRISES A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL HAVING COMBINED THEREWITH ABOUT 0.5 TO 3.0% BY WEIGHT OF AN ESTER OF PHOSPHOKRIC ACID, SAID ESTER BEING FORMED BY REACTING PHOSPHORIC OXYCHLORIDE WITH THE CRUDE PRODUCT OBTAINED BY SUBJECTING A COPOLYMER OF PROPYLENE AND BUTYLENE TO THE OXO PROCESS.