US2397702A - Agent for mineral oils and mineral oil composition containing the same - Google Patents

Description

UNITED STATES PATENT OFFICE AGENT FOR MINERAL OILS AND MINERAL OIL COMPOSITION CONTAINING THE SAME Herschel G. Smith, Wallingford, and Troy L. Cantrell, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a. corporation of Pennsylvania N Drawing. Application July 20, 1945,

' Serial No. 60,6,272

6 Claims.

This invention relates to improvement agents for mineral oils and mineral oil compositions containing the same.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, plain mineral oils often prove unsatisfactory, due to the attendant deposition on the engine surfaces, such as cylinder walls, pistons and rings, of varnish, gum or sludge. This effect is particularly serious in modern engines operating under severe conditions, such as Diesel engines, aviation, truck and tank engines. The problem has become increasingly serious, due to the trend toward higher efliciency, higher power out-put per unit weight per engine, reduction in the amount of oil employed in the lubrication system of the engine, and other conditions which tend to accelerate the deteriorating influences n mineral lubricating oil.

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 or 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 ring sticking and production of deposits on piston surfaces and in fixed parts of the combustion chamber. 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 known by the general term improvement agents or addition agents. Preparation of satisfactory compounded lubricants is a matter of considerable difiiculty. Some of the agents are of low potency so that 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 their rather low solubility, in general, further adds to the difficulties in preparing a useful lubricant.

One object of the present invention is the provision of improvement agents for engine oils effective proportions and which impart to the oil a plurality of functions.

Another object is the provision of addition agents which function (1) as negative catalysts to suppress the formation of deterioration or oxidation products, such as varnish, sludge and gum, (2) as loosening or suspending agents (detergents) to prevent ring sticking, varnishing, or coating of metallic surfaces by such reduced amounts of deterioration products as may be formed and (3) as suspending or dispersing agents for retaining very small particles of solid deterioration or contaminating materials in the oil; for example, particles of carbonaceous matter that find their way into the crankcase oil by passing the piston rings which cannot possibl be made absolutely tight.

Another object is the provision of new improvement agents capable of increasing the solubility or dispersibility of other agents, such as straight soaps or the like, when it is desirable also to acid such compounds to an oil in which said soaps and like agents are diflicultly soluble.

According to this invention, new improvement agents for mineral oils capable of achieving these and other objects are prepared by a series of steps which include: (1) forming a diaryl-chloro-phosphite by esterifying an alkylated phenol which contains at least one alkyl group having from 3 to 5 carbon atoms with phosphorus trichloride; (2) reacting said diaryl-chloro-phosphite with ricinoleic acid; (3) sulfurizing said ricinoleie acid reaction product; and (4) converting said sulfurized product to a metal salt.

These addition agents in solution in mineral oils perform four functions which are useful and advantageous in lubricants: (1) by virtue of their combined metal (e. g. calcium, etc.) suspending or detergent properties are imparted, as well as resistance to ring sticking; (2) the combined phosphorus imparts anti-bearing-corrosion and anti-ring sticking properties, as well as pressure carrying properties; (3) the combined sulfur serves to give pressure carrying properties to the oil and to retard corrosion of alloy bearings and (4) by virtue of the alkylated phenyl groups carrying at least one alkyl group having. from 3 to 5 carbon atoms, the improved oil has good antioxidant and oiliness properties and suspending and solubilizing characteristics.

Thus, according to the invention, there are provided new improvement agents which dissolved in the oil, impart thereto all the man desirable features which We wish to obtain, including the which can be incorporated in petroleum oils in several advantages, virtues and properties described hereinbefore. Furthermore, our new improvement agents are so soluble in motor oils of all types and degrees of refinement that we can incorporate them in any desired proportions to form clear solutions in lubricating oils, even in the most highly refined and most paraffinic of the heavy aviation oils, such as are specified in the most severe and exacting aviation services.

It is known that highly paraffinic oils, refined to the high degree necessary to secure such desirable properties as low carbon-forming effects and high viscosity indices (improved viscosity temperature relationships) are relatively poor solvents for decomposition products formed in use. Also, there is increased tendency to induce bearing corrosion. In this invention these undesirable properties of such oil are eliminated by the use of moderate amounts of our new compounding agents having cumulatively all the desired properties in the way of ready solubility in the oils and the other advantageous effects mentioned above. We can employ very highly refined paraifinic-type aviation oils that have the desired superior physical characteristics as regards these particular properties, and, at the same time, avoid any undesirable effects whatever from the use of such oils. In other words, the addition of our improvement agents, which are soluble in all proportions in the heavy highly refined paraffinic oils, enables us to secure all the properties desirable in the Way of oils of superior performance characteristics, as well as the effects of detergency, avoidance of ring sticking, sludge formation and corrosion of alloy bearings that might otherwise be encountered, and also to secure the desired effect of retarding oxidation due to the use of more highly refined oils of less tendency to oxidize combined with the use of a compound which actually retards oxidation.

Another important field of utility for the invention is in Diesel lubricating oils. Heretofore, it has been considered best to use naphthenetype oils dosed with certain compounding agents which are of undesirably low efiiciency and which moreover are not readily soluble even in the most naphthenic type of Coastal oils. Thus it has often been necessary to make a compromise even for the Coastal oils of greater solubility effect for compounding agents between the degree of refining and the solubility effect for the addition agents. It is quite unsatisfactory for most of these agents to use even a moderately refined parafiin type oil, as all or part of the addition agents heretofore used will often separate from the oil upon standing. For these reasons Diesel lubricating oils hitherto prepared have been rather unsatisfactory, in that they employ low grade oils of less degree of resistance to oxidation than would otherwise be desirable. With the present invention, we prepare an improved oil which performs satisfactorily in Diesel engines, employing a highly'refined parafiin-type of oil with control of ring sticking elTects, sludge formation and detergency efiects by mixing therewith any desired proportion of the new improvement agents disclosed herein.

The new improvement agents have another important advantage in that, in addition to being very oil-soluble, they act to disperse in mineral oils other improvement agents which are of themselves relatively insoluble. For example, in accordance with the present invention 1 per cent or more of calcium oleate or aluminum stearate can be dissolved in oil to form a stable dispersion with the aid of an equal quantity of one of our new agents. Thus, our new addition agents are sometimes useful where their own antioxidant and dispersing properties are not required for their value in dissolving other agents.

The new addition agents are conveniently prepared in the form of concentrated oil solutions which can readily be stirred into an oil to prepare a compound lubricant.

In preparing our new addition agents, we advantageously employ as a starting material an alkylated phenol or a mixture of alkylated phenols that contain one or more alkyl groups having from 3 to 5 carbon atoms. In other words, we may employ as our starting material a mono-, di-, or tri-alkyl phenol wherein said alkyl group is a propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, amyl, isoamyl, secondary amyl, or another isomeric pentyl radical. These higher alkylated phenols may not only be derived from phenol itself but also from any of the phenols containing short chain alkyl groups such as the cresols and xylenols. I

Of the various individual alkylated phenols which contain atfl'east one alkyl group having from 3 to 5 carbon atoms that may be used as starting materials in making our new addition agents there may be mentioned 2-isopropyl phenol; 4-tertiary-butyl phenol; 2-isoamyl phenol;

Z-tertiary-amyl phenol; 2,4-ditertiary-butyl phenol; 2-tertiary-butyl-4-secondary-butyl phenol;

2,6-ditertiary-butyl-4-methyl phenol; 4,6-dite'rtiary-butyl-Z-methyl phenol; 2,6-ditertiary-butyl-3-methyl phenol; 2,4,6-tritertiary-butyl phenol; 2,6-ditertiary-butyl-4-secondary-butyl phenol; 2,5-ditertiary-butyl-4-secondary-butyl phenol; etc. These alkylated phenols are conveniently prepared by the reaction of a primary, secondary, or tertiary olefin with a phenol.

As hereinabove mentioned, we may use mixtures of alkylated phenols that contain one or more alkyl groups having from 3 to 5 carbon atoms instead of using individual alkyl-ated phenols such as those mentioned in the preceding paragraph. For instance, we may use an of the alkylated phenols, obtained by reacting phenols with olefins, which are described in U, S. Patent No. 2,149,759. It is normally preferred to use the semi-liquid, light colored products described in said patent, Suitable mixtures of alkylated phenols can be obtained by taking a crude semiliquid phenol-olefin reaction product, made in accordance with said U. S. Patent No. 2,149,759, by passing a butane-butene gas mixture through per cent phenol at -180 F., in the presence of 5 per cent by weight of sulfuric acid, and then securing a 60, 70, or 80 per cent heart-cut (20-80, 15-85, or 10-90 per cent) thereof by subjecting it to fire and steam distillation in the presence of adequate caustic soda to insure mild alkalinity during distillation. It is to be understood that unfractionated phenol-olefin reaction products may be used in place of "heart-cuts separated therefrom in synthesizing satisfactory addition agents comprehended by our invention.

The particular alkylated phenol mixture which was employed as a starting material in the example set forth hereinbelow was a 60 per cent heart-cut of a phenol-butene reaction product made in accordance with said U. S. Patent No. 2,149,759 by separately collecting the 20-80 per cent cut obtained by steam or vacuum distillation; vacuum distillation being preferred, This heart-cut is a mixture of liquid, semi-liquid and crystalline butylated phenols. It is soluble in all proportions in lubricating oils and gasoline,

and soluble in most organic solvents and insoluble in water and NaOI-I solutions. It has the following properties:

Gravity, API 18.0-24.0 Sp. gr., 60/60 F 0.94650.9100 Viscosity, SUV, 100 F 60-100 Pour, F 30 to +15 Color, NPA 1.0-1.5 Free phenol, per cent nil Mineral acidity, per cent S03 equivalent nil Distillation, ASTM D 86-38:

Over point, F 375 End point, "F 538 at F 455 50% at "F 493 90% at "F 524 This phenol-butene reaction product contains varying amounts of butylated phenols such as 4-tertiary-butyl-phenol, 2-tertiary-butyl-4-secondary-butyl phenol, 2,4-ditertiary-butyl phenol, 2,6 ditertiary butyl-4-secondary-butyl phenol, 2,5 ditertiary butyl-4-second-ary-butyl phenol, 2,4,6-tritertiary-butyl phenol, 2,6-ditertiary-butyl-4-methyl phenol, 2,6-ditertiary-butyl-3-methyl phenol. 4,6-ditertiary-butyl-Z-methyl phenol and still other phenols containing a butyl group attached to the phenyl nucleus thereof. All of these butylated phenols have good antioxidant properties and are useful in making our new improvement agents, Those containing secondary or tertiary alkyl groups are particularly advantageous for use in preparing the improvement agents of the present invention.

The ricinoleic acid used is purified from c-astor oil fatty acids. Pure ricinoleic acid with a specific gravity of 0.945, a melting point of 17 C, and a boiling point of 250 C. mm. pressure) may be used, but in the example set forth hereinbelow a technical grade of ricinoleic acid was employed which had the following properties:

Recovery, per cent Sp. gI., 60/60 F 0.9398 Acid value 188 Iodine number 8'7 Saponification number 188 Unsaponifiable matter, per cent 0.5 Acetyl value 150 Freezing point, C 6 to -10 The following example which illustrates but does not limit the invention describes the preparation of one of our improved addition agents and an improved lubricating oil containing the same.

Example 1648 parts by Weight of the heart-cut of the reaction product of butene and phenol hereinbefore described was heated with 500 parts by weight of phosphorus trichloride at 500 F. for

16 hours, The product (I) had the following properties:

Gravity, API 8.8 Viscosity, SUV 100 F 1743 Neutralization number 135 Phosphorus, per cent 5.4 Chlorine, per cent 5.8

479 parts by weight of product (I) as described above was heated with 300 parts by weight of ricinoleic acid, such as was hereinbefore described, at 400 F. for 4 hours. The product (II) had a neutralization number of 69.5.

200 parts by weight of product (II) described Gravity, API 13.6 Viscosity, SUV 100 F 676 Sulfur, per cent 1.74 Phosphorus, per cent 1.69 Ash as sulfate, per cent 4.44

Three per cent of this concentrate was added to motor lubricating oil to improve the antioxidant and detergent properties. A comparison of the oils is as follows:

Oil contain- Description Base oil ing addition agent Gravity, API 21. 4 20. 9 Viscosity, SUV:

F 1, 455 l, 441 210 F 82.5 81.7 Flash, 00, "F 420 415 File, ()0, F 490 490 Pour, F 0 +5 Sulfur (B), percent 0. 31 Copper strip test 212 F., 3 hr. Passes Passes Ash (as sulfate), percent. 0.087 Carbon residue, percent. 0. 25 0. 23 Neutralization No. 0.03 0. l3

Our new addition agents possess great oiliness properties, and therefore oils containing the same can be used for some special lubricating services, such as for the break-in of motors and for operation of the same under severe conditions. An oil containing small amounts of the new addition agent described in the example above has superior oiliness and detergent properties, protects bearings from corrosion, and reduces the amount of sludge formation and ring sticking at high temperatures. The tendency of oils to cause ring sticking in engines is conveniently evaluated by the testing method which is described in the paragraph that begins in line 55 in column 1 on page 4 of U. S. Patent No. 2,342,433. When a base oil having the properties set forth in the above example and the same oil containing 3.0 per cent of the new addition agent described in the above example was tested in accordance with the test set forth in U. S. Patent No. 2,342,433, it was found that the piston rating of the base oil was 4 and the piston rating of the oil containing the addition agent was 1.

While in the above example we converted product (III) to a metal salt by heating it with lime, it is to be understood that other metal salts in addition to the calcium salt may be made by reacting product (III) with other metallic oxides and hydroxides, such as those of aluminum and zinc.

In preparing improved lubricants, the optimum proportion of the agent to be introduced into lubricating oils depends on the severity of the service conditions and the degree to which the oil itself tends to form gum or varnish. Ordinarily, from 0.5 to 5.0 per cent by weight of our new improvement agent on the oil is suitable. The improved lubricants so obtained have the ad vantageous properties described hereinabove.

By adding varying proportions of this improvement agent to commercial lubricating oils, a wide range of improved lubricants is readily obtained.

Furthermore, the improvement agent described in the above example is so soluble in mineral oils that concentrated solutions thereof can be readily prepared. These concentrates are also useful improvement agents in making commercial lubricants and can be readily incorporated and blended with various lubricating oils and bases to produce commercial lubricants.

These concentrates can also be prepared with advantage by incorporating mineral oil with the acid reaction product (III) prior to reacting the same with the metal oxide or hydroxide.

While the improvement agents of the present invention have been described in reference to compounding engine lubricating oils for the primary purpose of preventing ring sticking, their field of usefulness is not confined to that application. They can be used in oils wherever their properties may be desired. Sometimes they are used for their dispersive powers on other agents, when their own antioxidant and detergent properties are not needed.

Stated otherwise, another important advantage of the agents of the present invention is that in addition to being highly soluble in oils themselves, they are efiective to disperse in mineral oils certain soaps which are of themselves difiicultly soluble, for example, calcium oleate or aluminum stearate. Again, sulfurized sperm oil soap is a desirable addition agent to oils, but its low solubility prevents incorporation of more than a rather small quantity in paraffin base oils. By the present invention 1 per cent or more ofsuch soap can be dispersed in oil to form a stable dispersion by including an equal amount of the new improvement agents of this invention. Thus in the practice of the present invention, our new agents may be used in conjunction with other previously known addition agents, in compounding lubricating oils to improve their properties. Thus in the practice of the present invention, various embodiments thereof may be employed in addition to the illustrative embodiments shown hereinbefore.

We claim:

1. A suitable additive for mineral oils which comprises a metal salt of a sulfurized derivative of a ricinoleic acid reaction product of a diarylchloro-phosphite which has been made by esterifying an alkylated phenol which contains at least one alkyl group having from 3 to 5 carbon atoms with phosphorus trichloride.

2. A calcium salt of a sulfurized derivative "of a ricinoleic acid reaction product of a diaryl-chlorophosphite which has been made by esterifying an alkylated phenol which contains at least one alkyl group having from 3 to 5 carbon atoms with phosphorus trichloride.

3. A calcium salt of a sulfurized derivative of a ricinoleic acid, reaction product of a diary]- chloro-phosphite which has been made by esterifying a butylated phenol which contains at least one butyl group with phosphorus trichloride.

'4. A mineral oil composition containing from 0.5 to 5.0 per cent by weight of a product as defined in claim 1.

5. -A mineral oil composition containing from 0.5 to 5.0 per cent by weight of a product asdefined in claim 2.

6. A mineral oil composition containing from 0.5 to 5.0 per cent by weight of a product as defined in claim 3.,

HERSCHEL G. SMITH. TROY L. CANTRELL.