US2506902A - Addition agents for mineral oil lubricants and compositions containing the same - Google Patents

Description

Patented May 9, 1950 ADDITION AGENTS FOR MINERAL OIL LU- BRICANTS AND COMPOSITIONS CONTAIN- ING THE SAME Herschel G. Smith, Wallinzford, and Troy L. Cantrell, Lansdowne, Pm, and John G. Peters, Audubon, N. J., asslgnors to Gulf Oil Corporation, Pittsburgh, Pa., a. corporation of Pennsylvania No Drawing.

12 Claims. 1

This invention relates to addition agents for mineral oil lubricants and compositions containing the same, and more particularly it relates to addition agents which confer improved pressure-carrying, bearing corrosion-inhibiting and detergent properties on mineral oil lubricants.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, plain mineral lubricating oils often prove unsatisfactory in service because of the attendant deposition on the engine surfaces, such as the cylinder walls, pistons and rings, of varnish, gum, or sludge. These effects are particularly serious in modern engines operating under severe conditions, such as Diesel engines and aviation, truck, and tank engines. The problem has become increasingly serious due to the trend toward (1) higher efificiency, or higher power output per unit weight per engine, (2) reduction in the amount of oil employed in the lubricating system of the engine, and (3) other conditions which tend to accelerate deteriorating influences on mineral lubricating oils.

Formation of so-called varnishes and sludges on engine surfaces is due to oxidation or polymerization effects (or both) on the lubricating oils, as well as to like effects on or from products of combustion of the fuels which find their way ,by leakage into the engine crankcase and other parts of the engine.

The presence of these substances is disadvantageous for many reasons. In particular, the oil and fuel oxidation products tend to increase ringsticking and production of deposits on piston surfaces and in fixed parts of the combustion cham ber. sludges are formed in the crankcase of the engine, and the rate of corrosion of bearing surfaces is increased, especially with bearing alloys of the types now in use.

Petroleum oils intended for use under the severe conditions described are almost always compounded with a mixture of substances each intended to counteract one or more of the undesirable effects noted. These substances, which fall into a wide variety of chemical classifications, are generally known as "improvement agents or addition agents. However, preparation of satisfactory compounded lubricants is a matter of considerable difiiculty. Some of the agents are of low potency, that is, a rather large amount has to be added to achieve the desired result. Often two or more agents are more or less incompatible with each other; and since the addition agents heretofore employed usually have a Application May 26, 1947, Serial No. 750,635

rather low solubility the difficultles of preparing a useful lubricant are enhanced.

It is also a frequent characteristic of prior art addition agents that they are extremely dark in color. When such dark-colored addition agents are added in effective amounts to a highly refined light-colored mineral oil, they often impart such a degree of color to the oil as to render the oil unmarketable.

It is an object of this invention, therefore, to provide addition agents for mineral oil lubricants which serve the functions of (1) inhibiting the corrosion of bearings, (2) acting as a loosening or suspending agent (detergent) to prevent ringsticking, varnishing or coating of the metallic surfaces of internal combustion engines, and (3) acting as a suspending or dispersing agent for dispersing very small particles of deterioration products or contaminating materials in the oil.

Another object of this invention is to provide an addition agent for mineral oil lubricants which is readily soluble and extremely lightcolored, and which may be added to any lightcolored mineral oil lubricant without materially affecting the color thereof.

It is a further object of this invention to provide an addition agent for mineral oil lubricants which confers markedly improved extreme pressure characteristics on such mineral oil lubricants.

In our copending application, Serial No. 729,672, filed February 19, 1947, we have disclosed and claimed mineral oil lubricants containing as addition agents (1) a reaction product of octyl phenol with a sulfur chloride and a relatively small amount of phosphorus sesquisulfide, and

(2) the condensation product of formaldehyde and a substantially neutral metal salt of the aforesaid reaction product, the said metal being a metal of group II of the periodic table selected from the group consisting of magnesium, calcium, barium and zinc. We have now found that an excellent addition agent may be prepared by substituting stannous tin for the aforesaid group II metals.

Accordingly, the objects of our invention are achieved by providing mineral oil lubricants containing as addition agents (1) a reaction prodnot of an octyl phenol with a sulfur chloride and a relatively small amount of phosphorus sesquisulfide, and (2) the condensation product of formaldehyde and a substantially neutral stannous salt of the aforesaid reaction product. We consider such condensation products and the method of preparing them novel, and as parts 3 of our invention. The reaction products of an octyl phenol with a sulfur chloride and a relatively small amount of phosphorus eesquisulilde, as well as the method of preparing such reaction products, are claimed in our aboveidentified copending application.

We prepare the reaction product of an octyl phenol with a sulfur chloride and phosphorus sesquisulflde in accordance with our prior copending application, Serial No. 729,672. In accordance therewith, we react an octyl phenol with from 0.5 to 30 per cent by weight on the octyl phenol of a sulfur chloride and from 0.1 to 5 per cent by weight on the octyl phenol of phosphorus sesquisulfide. The reaction may take place at room temperature, and it usually is preferred to initiate the reaction at such temperature and then raise the temperature to no higher than 350 F. to complete the reaction;

However the reaction may take place at any temperature ranging from room temperature to 350 F., provided care is taken that the latter temperature is not exceeded. If the temperature of 350 F. is exceeded to any great extent, especially in the initial stages of the reaction, the reaction product formed will tend to be dark-colored and insoluble in mineral oil lubricants. It is desirable to use a volatile solvent in the preparation of the octyl phenol reaction product. A wide variety of solvents may be employed such as benzene, toluene, hexane, carbon tetrachloride, chloroform, cyclohexane and others. The solvent should be inert in the reaction and for this reason materials containing reactive hydroxyl groups and the like, such as alcohols and the like, should not be employed. Since the solvent is removed from the reaction product after the reaction has been completed, it is desirable that the solvent be relatively volatile and therefore a solvent having a boiling point above 320 F. should not be used.

We may use any octyl phenol in the preparation of the reaction product. The octyl phenols may be prepared by any method known to the art, but they are preferably made in accordance with the procedure shown in U. S. Patent No. 2,149,759. In accordance with the procedure of said patent, phenol is reacted with a mixture of isomeric octenes, such as is available at the refinery in commercial diisobutylene polymer, in the presence of a condensing agent such as concentrated sulfuric acid. The octyl phenol prepared in this manner is a mixture of isomeric octyl phenols, but it is believed to contain a preponderant amount of tetramethyl butyl phenol (para-iso-octyl phenol). However, our invention is not limited to the use of any specific octyl phenol or to octyl phenols derived from any specific source. Thus any one of the isomeric octyl phenols or mixtures thereof may be employed with good results in accordance with our invention.

The sulfur chloride used in accordance with our invention is preferably sulfur monochloride. However, other sulfur chlorides such as sulfur dichloride and sulfur tetrachloride or mixtures thereof may be employed. When sulfur tetrachloride is employed alone, it is preferred to use smaller proportions thereof within the range given because the larger proportions tend to produce products which are darker in color than when the other sulfur chlorides are employed. As previously stated, the sulfur chloride is reacted with the phenol in an amount 4 ranging from 0.5 to 30 per cent by weight on the octyl phenol.

Example I.As an example of the preparation of the octyl phenol reaction product, 1374 pounds of an octyl phenol, 13 pounds of phosphorus sesquisulfide (P483) and 1331 pounds of benzene were placed into a reaction vessel equipped with an agitator, means for heating and cooling, and a reflux condenser. Then 270 pounds of sulfur monochloride (SaClz) were added slowly while keeping the reaction mixture at a temperature of 60 F. The addition of the sulfur monochloride required approximately 4 hours. At this time the temperature was raised to 180 F. and the mixture was refluxed for 20 hours at this temperature in order to complete the reaction. At the end of this time the benzene was distilled off and the residue was heated to 250 F. under a vacuum of approximately 15 inches of mercury in order to strip off all of the benzene. The residue was then diluted with 1500 pounds of a mineral oil having the following properties:

Gravity, API 32.0 Viscosity, SUV: F 72.4 Flash, 00, F 345' Fire, 00, F 395 Pour, F +20 Color, NPA 1.5 Carbon residue, per cent 0.01 Neutralization No 0.02

' The solution of the octyl phenol reaction product in the mineral oil had the following properties:

Gravity, API 17.3 Viscosity, SUV: 100 F 1103 Flash, 00, F 385 Fire, 00, "F 450 Pour, F +5 Color, NPA 2.50 Sulfur, per cent r 5132 The reaction products obtained from octyl phenol, a sulfur chloride and phosphorus sesquisulflde are excellent addition agents for mineral oil lubricant compositions. They are readily soluble in all types of mineral oils, that is, parafiinic, naphthenic or mixed base mineral oils, and can be blended with mineral oils in high proportions as is shown in the preceding example. This excellent solubility of our new addition agents enables the preparation of concentrated solutions thereof which may then be diluted down to the proportions desired in the final mineral oil lubricant composition. As shown in our copending application, the octyl phenol reaction products confer excellent pressure-carrying, bearing corrosion-inhibiting and detergent properties on the mineral lubricating oils with which they are incorporated. For these purposes our new addition agents are generally added to mineral oils in minor amounts, say from 0.1 to 15 per cent by weight on the mineral oil. Ordinarily small amounts as low as 0.1 per cent by weight are suflicient to effect the desired improvement. However, when extreme pressure properties are to be conferred on a mineral lubricating oil composition, it will ordinarily be desirable to use higher amounts, as high as 15 per cent.

In accordance with the present invention, we have found that the properties of mineral oil lubricating compositions containing the octyl phenol reaction products described above may be condensation derivative of the above described reaction product. More particularly, there is formed a substantially neutral stannous salt of the reaction product of an octyl phenol with a sulfur chloride and phosphorus sesquisulflde prepared in accordance with the preceding disclosure, and the resulting salt is condensed with formaldehyde or a formaldehyde-yielding compound. When the resulting condensation derivative and the original reaction product are both added to a mineral oil lubricant composition, the properties of the composition are still further improved, particularly in regard to inhibiting bearing corrosion.

The formation of a substantially neutral stannous salt of the reaction product of an octyl phenol with a sulfur chloride and a phosphorus sesquisulflde may be accomplished in any conventional manner known to the art and preferably by heating of the reaction product and stannous oxide or hydroxide. formed by the double decomposition method; that is, by first forming an alkali metal salt by neutralization with an alkali metal hydroxide, such as potassium or sodium hydroxide, and then replacing the sodium ion with stannous tin by reaction with a water-soluble stannous salt, such as stannous chloride.

The condensation of the substantially neutral stannous salt of the above disclosed reaction product with formaldehyde or a formaldehyde-yielding compound is accomplished by heating to a temperature not in excess of 275 F. Useful formaldehyde-yielding compounds are trioxymethylene, paraformaldehyde and the like. The amount of formaldehyde used ranges from 0.5 to 2 mols per mol of octyl phenol used in making the reaction product of an octyl phenol with a sulfur chloride and phosphorus sesquisulfide. Formaldehyde-yielding compounds are employed in amounts equivalent to the amount of formaldehyde yielded by such compounds within the range above stated. Following condensation with the formaldehyde or formaldehyde-yielding compound, the condensation product is dehydrated.

The following example illustrates the preparation of the condensation derivative of our invention.

Example II.--Thirteen hundred thirty one pounds of an octyl phenol, 65 pounds of phosphorus sesquisulfide (P483) and 736 pounds of benzene were placed into a reaction vessel equipped with an agitator, means for heating and cooling, and a reflux condenser. Then 270 pounds of sulfur monochloride (S2012) were added slowly while keeping the reaction mixture at a temperature of 60 F. The temperature was then raised to 180 F. and the mixture was refluxed at this temperature for 20 hours. The benzene was then distilled off and the residue was heated to 280 F. under a vacuum of about inches of mercury. The resulting reaction product was then diluted with 1900 pounds of a mineral lubricating oil having the same properties as shown in Example I, and then 240 pounds of sodium hydroxide were added in 30 per cent solution, and the mixture heated to 210 F. for a period of 5 hours. Then 570 pounds of stannous chloride in water solution and 510 pounds of 37 per cent formaldehyde solution were added. The mixture was then heated with agitation at a temperature of 275 F. for 2 hours, distilling oil the water. The product The salt may also be was then dried under a vacuum of 15 inches of mercury and filtered through a continuous filter. The product obtained has the following properties:

The above described condensation derivative is also readily soluble in mineral lubricating oils, and as disclosed in Example II may conveniently be prepared as a concentrate in mineral lubricating oils. When both the above described reaction product and the condensation derivative thereof are incorporated in a mineral oil lubricant composition as previously disclosed, minor amounts of both agents are ordinarily sufficient to effect the desired improvement in pressure-carrying, bearing corrosion-inhibiting and detergent properties. The total amount of both agents will generally range from 0.1 to 15 per cent by weight on the mineral lubricating oil. Within this range, it is preferred to employ equal amounts by weight of the two agents, but the proportions of the two agents with respect to each other may vary from 10 to per cent by weight of the reaction product, and from 90 to 10 per cent by weight of the condensation derivative.

The following table illustrates the improved mineral oil lubricant compositions obtained by the use of our new addition agents. In the table, composition A is a good grade uncompounded SAE 30 motor oil, composition B is composition A blended with 1 per cent by weight of the reaction product prepared in accordance with Example I, and composition C is composition A blended with 1 per cent by weight of the reaction product prepared in accordance with Example I and 1 per cent by weight of the condensation derivative prepared in accordance with Example II.

A B C Gravity, API 29.3 29.0 28. 8 Viscosity, SUV

210 F 67. 5 67.1 66. 8 Viscosity Index- 104 103 102 Cloud, F none Pour, "F +5 5 +5 Aging Test, 32 F 24 Hrbright bright bright Room Temp. 15 days bright bright bright Color, A l. 75 l. 75 2. 25 Appearance bright bright bright Sulfur, B, Per Cent 0.12 0. 19 0.17 Carbon Residue, Per Cent 0.11 0.13 0. 24 Precipitation No. nil nil Centrifuge Test, Separation, Per Cent:

1500 R. P M., Room Temp, 2 Hrnil nil Neutralization No 0.02 0.02 0. 04 Chevrolet 36 Hour Engine Test;

CBC Designation Engine Rating 75-541 9549 "29 Falex Wear Test:

1000 Lb. Gauge Load, 15 min.:

Wear: No. of Teeth falls 0 0 Gauge Load at Seizure, Lb 1, 100 1,000

As may be seen from the above data, the color 01. the base lubricating oil remains unchanged and bright notwithstanding the addition of our new addition agents. As shown by the data on the Falex Wear Test, even small amounts of our new addition agents effectively improve the pressure-carrying properties of the base oil. When larger amounts are used the improvements obtained in pressure-carrying properties are even more striking. The remarkably effective detergent and bearing-corrosion inhibiting properties imparted to the base oil are shown by the data on the Chevrolet 36 hour engine test. In the hyphenated figures shown thereunder, the figure to the left of the hyphen indicates the freedom from engine deposits expressed in per cent, the larger the per cent (approaching 100 as a limit) the cleaner the engine. The marked improvement in detergent effects obtained from the use of our new addition agents is clear. The figure to the right of the hyphen indicates the amount of bearing corrosion expressed in milligrams loss in weight of a standard bearing. As shown under composition B, a mineral oil lubricant composition containing the reaction product of an octyl phenol with a sulfur chloride and phosphorus sesquisulfide reduces the loss in weight of the bearing from 541 milligrams to 49 milligrams. As shown under composition C when the mineral oil lubricant composition contains both the aforesaid reaction product and the condensation derivative thereof, a still further improvement is obtained, the loss in weight of the bearing being only 29 milligrams. Our new addition agents clearly confer excellent bearing corrosion-inhibiting properties. Finally, the above data show the excellent stability and solubility of our new addition agents.

The Chevrolet 36 hour engine test referred to above is an accepted standard test designed to determine the oxidation and bearing corrosion characteristics of engine crank case oils designed for use under heavy duty service conditions. In this procedure, the crank case lubricant is evaluated with respect to its stability or resistance to oxidation, bearing corrosion and the deposition of contaminants resulting from decomposition and oxidation or other changes that occur in the lubricant in service. The procedure involves the intermittent operation of a special fi-cylinder automotive test engine at constant speed and load for a total of 36 hours subsequent to a run-in period of 8 hours at graduated speeds and loads. Prior to each test a complete set of new piston rings is installed and two new weighed copper-lead test bearings are installed in symmetrical location. Performance of the test 011 is judged by examination of the power section of the engine for deposits and by ascertaining the weight loss of the test bearings.

While we have shown in the examples the preparation of compounded lubricating oils, our invention is not limited thereto, but comprises all mineral oil lubricant compositions containing our new addition agents, such as greases and the like.

As used in the appended claims, the term formaldehyde includes formaldehyde-yielding compounds as well as formaldehyde itself.

What we claim is:

from 0.5 to 30 per cent by weight of the octyl phenol of a sulfur chloride and from 0.1 to 5 per cent by weight of the octyl phenol of phosphorus sesquisulflde, neutralizing the reaction product with an alkali metal hydroxide, reacting the neutralized reaction product with a water-soluble salt of stannous tin to form a substantially neutral stannous salt of the reaction product, condensing the substantially neutral stannous salt at an elevated temperature not exceeding 275 F. with from 0.5 to 2 mols of formaldehyde per mol of octyl phenol used in making said reaction product, and recovering the resulting condensation product.

3. An addition agent for mineral oil lubricants obtained by the process of claim 1.

4. The process of claim 2, wherein the watersoluble stannous salt is stannous chloride.

5. The process of preparing an addition agent for mineral oil lubricants which comprises simultaneously reacting at a temperature ranging from room temperature to 350 F. an octyl phenol with from 0.5 to 30 per cent by weight of the octyl phenol of a sulfur chloride and from 0.1 to 5 per cent by weight of the octyl phenol of phosphorus sesquisulfide, neutralizing the-reaction product obtained thereby with stannous hydroxide to obtain a substantially neutral reaction product, condensing the neutral reaction product with formaldehyde by heating at a temperature not greater than 275 F. the neutralized reaction product and from 0.5 to 2 mols of formaldehyde permol of octyl phenol used in making said reaction product.

6. The process of claim 5, wherein the octyl phenol, sulfur chloride and phosphorus sesquisulfide are reacted in the presence of a volatile solvent, and the volatile solvent is distilled of! prior to neutralizing the reaction product with stannous hydroxide.

7. The process of preparing an addition agent for mineral oil lubricants which comprises simultaneously reacting at a temperature ranging from room temperature to 350 F. and in the presence of a volatile solvent having a maximum boiling point of 320 F. an octyl phenol with from 0.5 to 30 per cent by weight of the octyl phenol of sulfur monochloride and from 0.1 to 5 per cent by weight of the octyl phenol of phosphorus sesquisulfide, distilling off the solvent, diluting the residue with a mineral lubricating oil, neutralizing the diluted residue with stannous hydroxide to obtain a substantially neutral reaction product, condensing the neutral reaction product with formaldehyde by heating at a temperature not greater than 275 F. the neutralized reaction 1. The process of preparing an addition agent for mineral oil lubricants which comprises simultaneously reacting at a temperature ranging from room temperature to 350 F. an octyl phenol with from 0.5 to 30 per cent by weight of the octyl phenol of a sulfur chloride and from 0.1 to 5 per cent by weight of the octyl phenol of phosphorus sesquisulfide, forming a neutral stannous salt of the reaction product, and con densing the neutral stannous salt at an elevated temperature not exceeding 275 F. with from 0.5 to 2 mols of formaldehyde per mol of octyl phenol used in making said react on product.

2. The process of preparing an addition agent for mineral oil lubricants which comprises simultaneously reacting at a temperature ranging from room temperature to 350 F. an octyl phenol with product and from 0.5 to 2 mols of formaldehyde per mol of octyl phenol used in making said reaction product, dehydrating the resulting condensation product, and recovering a solution of the dehydrated condensation product in a mineral lubricating oil.

8. An addition agent for mineral oil lubricants .carrying, bearing corrosion-inhibiting and detergent propcrties on the composition of (1) the simultaneous reaction product formed at a tem perature ranging from room temperature to 350 F. of an octyl phenol with from 0.5 to 30 per cent by weight of the octyl phenol of a sulfur chloride and from 0.1 to per cent by weight of the octyl phenol of phosphorus sesquisulfide, and (2) the condensation product formed at an elevated temperature not exceeding 275 F. of formaldehyde and a substantially neutral stannous salt of (1), the amount of formaldehyde being from 0.5 to 2 mols per mol of octyl phenol employed to form (1), and the amounts of (1) and with respectto each other ranging from to 90 per cent by weight of (1) and from 90 to 10 per cent by weight of (2) 11. A lubricant composition comprising a major amount of a mineral lubricating oil and a minor amount, from 0.1 to per cent by weight on the oil of: (1) the simultaneous reaction product of an octyl phenol with from 0.5 to per cent by weight of the octyl phenol of sulfur monochloride and from 0.1 to 5 per cent by weight of the octyl phenol of phosphorus sesqulsulfide, said reaction product having been prepared at a temperature ranging from room temperature to 350 F. and in the presence of a volatile solvent which is substantially distilled off; and (2) the anhydrous condensation product formed at an elevated temperature not exceeding 275 F. of formaldehyde and a substantially neutral stannous salt, the

amount of formaldehyde being from 0.5 to 2 mols per mol of octyi phenol employed to form (1); and the amounts of (1) and (2) with respect to each other ranging from 10 to per cent by weight of (1) and from 90 to 10 per cent by weight of (2), and totaling from 0.1 to 15 per cent by weight on the mineral oil lubricating composition.

12. A lubricating composition in accordance with claim 11, wherein the amounts of (1) and (2) are equal.

HERSCHEL G. SMITH. TROY L. CANTRELL. JOHN G. PETERS.

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

UNITED STATES PATENTS Number Name Date 2,301,002 Zerwick Nov. 3, 1942 2,362,624 Gaynor et a1 Nov. 14, 1944 2,409,687 Rogers et al Oct. 22, 1946 2,415,833 Mikeska et a1 Feb. 18, 194'? 2,438,875 Reifl' Mar. 30, 1948

Claims (2)

1. THE PROCESS OF PREPARING AN ADDITION AGENT FOR MINERAL OIL LUBRICANTS WHICH COMPRISES SIMULTANEOUSLY REACTING AT A TEMPERATURE RANGING FROM ROOM TEMPERATURE TO 350*F. AN OCTYL PHENOL WITH FROM 0.5 TO 30 PER CENT BY WEIGHT OF THE OCTYL PHENOL OF A SULFUR CHLORIDE AND FROM 0.1 TO 5 PER CENT BY WEIGHT OF THE OCTYL PHENOL OF PHOSPHORUS SESQUISULFIDE, FORMING A NEUTRAL STANNOUS SALT OF THE REACTION PRODUCT, AND CONDENSING THE NEUTRAL STANNOUS SALT AT AN ELEVATED TEMPERATURE NOT EXCEEDING 275*F. WITH FROM 0.5 TO 2 MOLS OF FORMALDEHYDE PER MOL OF OCTYL PHENOL USED IN MAKING SAID REACTION PRODUCT.

10. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL AND MINOR AMOUNTS, SUFFICIENT TO CONFER IMPROVED PRESSURECARRYING, BEARING CORROSION-INHIBITING AND DETERGENT PROPERTIES ON THE COMPOSITION OF (1) THE SIMULTANEOUS REACTION PRODUCT FORMED AT A TEMPERATURE RANGING FROM ROOM TEMPERATURE TO 350*F. OF AN OCTYL PHENOL WITH FROM 0.5 TO 30 PER CENT BY WEIGHT OF THE OCTYL PHENOL OF A SULFUR CHLORIDE AND FROM 0.1 TO 5 PER CENT BY WEIGHT OF THE OCTYL PHENOL OF PHOSPHORUS SESQUISULFIDE, AND (2) THE CONDENSATION PRODUCT FORMED AT AN ELEVATED TEMPERATURE NOT EXCEEDING 275*F. OF FORMALDEHYDE AND A SUBSTANTIALLY NEUTRAL STANNOUS SALT OF (1), THE AMOUNT OF FORMALDEHYDE BEING FROM 0.5 TO 2 MOLS PER MOL OF OCTYL PHENOL EMPLOYED TO FORM (1), AND THE AMOUNTS OF (1) AND (2) WITH RESPECT TO EACH OTHER RANGING FROM 10 TO 90 PER CENT BY WEIGHT OF (1) AND FROM 90 TO 10 PER CENT BY WEIGHT OF (2).