US2226335A - Lubricating oil composition, constituent thereof, and method of manufacturing the same - Google Patents

Description

Patented Dec. 24, 1940 PATENT OFFICE LUBRICATING OIL COMPOSITION, CONSTIT- UENT THEREOF, AND METHOD OF MAN-- UFACTURING THE SAME Troy Lee Cantrell and James Otho Turner, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of- Pennsylvania No Drawing. Application September 14, 1936, Serial No. 100,786

8 Claims.

Our invention relates to lubricating oils and in particular to lubricating oil compositions containing an oil-soluble agent or agents effective to impart so-called extreme-pressure characteristics thereto, and also having certain additional advantages as set forth hereinbelow.

Despite the many technical advances which have been made in the arts of refining and applying lubricating oils, modern lubricating oils and bearings often fail to perform satisfactorily. It is well known in the art that straight petroleum lubricants have fairly well defined limits of bearing speeds, pressures and temperatures, with- .in which they will give acceptable service. These limitations are often reached and even exceeded in modern engines, gears and the like, resulting in machines that cannot be satisfactorily lubricated by straight mineral oils. Such modern designs havebeen brought about through constant attempts on the part of engineers to improve engines and machines with respect to compactness, speed, power and acceleration. In order to provide satisfactory lubrication for modern designs and keep pace with new mechanical improvements in design, it is necessary to provide lubricating compositions having improved lubricating value ascompared with straight lubricating oils and which will give satisfactory service under drastic lubricating conditions under which straight mineral oils would fail to perform satisfactorily.

Thus, considerable attention is being paid to the development of lubricating oil compositions which are capable of giving satisfactory service under high pressures, such compositions being generally known in the art as extreme-pressure or EP lubricants. A number of materials have been developed which, when added to hydrocarbon oil, materially increase the extreme-pressure properties of the oil; the resultant compositions give moreacceptable service under higher. pressures between bearing surfaces than is true of the untreated oil. Some of these agents are extremely efl'ective but too expensive for general use, and others, while contributing satisfactory extreme-pressure properties'to the oil, are unsatisfactory for other reasons. A primary requisite of any improvement agent is good oil-solubility under service and marketing conditions; such agents when added to hydrocarbon oils in small amounts should not impart to the resulting composition a hazy or cloudy appearance, should not deposit out when the compositions are stored and packaged prior to sale, and should not attack metal surfaces of containers after being packaged and stored. The improvement agent should also be highly elfective per unit concentration in the lubricating oil compositions; otherwise it would be necessary to add such an amount of the improvement agent as to substantially modify many of the desirable physical properties of the lubricating oil itself. Such oils have been carefully refined to meet exacting specifications, and if it is necessary to incorporate therein relatively large amounts of some agent or agents differing in physical properties from the oil itself, the resulting compositions may prove unsatisfactory for the purposes for which the lubricating oils were prepared. In general it is desirable that any improvement agent-should be effective at concentrations not exceeding 1 or 2 per cent, or at the most 5 per cent, by weight of the lubricating oil.

For many purposes it is not necessary to increase the load-carrying properties of lubricating oils to several times the load-carrying properties of the originaloils. For example, in the lubrication of automotive engines, difficulty is frequently encountered at points where the pressures between bearing surfaces are not extremely high. Difiiculties are thus frequently encountered in maintaining effective lubrication between piston rings and the side walls of the cylinders, due to the fact that the temperatures of the surfaces may run very high. With ordinary mineral lubricating oils it may be impossible or diflicult to provide safe and effective lubrication for mechanically eflicient engines having a tendency to develop high temperatures at this point. While this difliculty is due primarily to temperature, it has been foundthat lubricating oils containing small amounts of extreme-pressure agents give better results under these conditions; these results have been variously'explained but are probably due to the fact that such extremepressure agents wet or adhere to the metal and the oil wets or adheres to the extreme pressure agent.

It is, therefore, an object of our invention to provide an improvement agent or agents of the character indicated herein, having the property of imparting desirable extreme-pressure characteristics to hydrocarbon oils when incorporated therein, which agent or agents shall be free from many or all of the disadvantages of agents previously employed for the same general purpose, as well as inexpensive to produce.

A further object of our invention is to provide improved lubricating compositions comprising carrying the absorption of olefin farther is to latter being a recovered acid obtained from acid make the anti-oxidant product less capable of sludge produced in Washing hydrocarbon oil with absorbing the desired amount of phosphorus in sulfuric acid. The 90 per cent phenol employed the final stage. v

5 When the anti-oxidant starting material is I O prepared from phenol (CsH5OH) Itself, e. g. 90 f No L050 per cent phenol, the degree of absorption of ole- Memflg pomt' camnary tube- F fin may be carried farther, for example to about Color- NPA 5 10 the assumption that the olefin is madeup entirely hour The operation product Ethylene (021-14) on the other hand r is insufficiently reactive requiring the use of assure of from 15 to fuming sulfuric acid and does not sumqigm] duce the acidity ofth Original I 08560 F m Mn sfartmg I n I f [I b 5%, WW W WWW mulq content substantially exceeds 5 per cent, the resulting product anti-oxidants, prepared as set forth above and in the aforesaid co-pending applications, having physical properties within the following range:

Gravity: API 15.0 to 25.0 Specific gravity:

60/60 F 0.9659 to 0.9042 Viscosity, SUV at F.: seconds 150 to (solid) Color Water white to '7 (NPA) Pour point (liquids only): F 0 to 30 Melting point (solids only) F'- 80 to 225 Our invention in its broadest aspects, however, is not limited to the preferred starting material mentioned hereinabove but contemplates the manufacture of inhibitors of the general class described from any alkylated phenols so long as such alkylated phenols possess definite anti-oxidant properties, are insoluble in water, insoluble or only slightly soluble in dilute alkali, and are permanently soluble up to 5 per cent in paraffin oils. employ as startingmaterials anti-oxidants prepared by reacting .various light cracked hydrocarbon distillates and other normally liquid olefinic hydrocarbon mixtures with phenol, in the presence of sulfuric acid, as described in the aforesaid copending applications. It is a requisite of such olefin-phenol reaction products, however, insofar as the present process is concerned, that one or more secondary and/or tertiary carbon linkages be present in the compound.

The anti-oxidant value of this starting material should be such that the addition of 0.01 per cent by weight thereof to standard gasoline stock having an oxygen stability test (B. G. C. Method) of, say, minutes, will raise the oxygen stability test to at least 240 minutes. Less potent anti-oxidants areunsuitable as starting materials.

As aforesaid, we prepare our present improvement agents by reacting anti-oxidants of the general character described hereinabove with phosphorus oxychloride. The reaction is conducted by mixing phosphorus oxychloride with the anti-oxidant material in the desired amount and heating the mixture until the latter is substantially free from chlorine or chlorides, temperatures of around 300 or 400 F. being suitable for this purpose.

In general we have found it advantageous to limit the amount of phosphorus oxychloride added so as to yield a product containing from about 1 to 5 per cent of phosphorus, assuming the anti-oxidant starting material to be free or relatively free from diluents; if the phosphorus ,mately 7 soluble in the higher gravity oils;

tends to be-insufiiciently soluble in lubricating oils, especially highly paraffinic lubricating oils. Also, in such case, the product tends to be too active at temperatures below, say, 250 F. By limiting the addition of phosphorus oxychloride to such an extent as will leave some of the original anti-oxidant material unaltered, for example by adding a sufficient amount-of phosphorus oxychlorideto a concentrated anti-oxidant to yield a product containing around 1 to 3 per cent of phosphorus, it is possible to obtain products which possess desirable extreme-pressure characteristics while at the same time retaining to a considerable extent the anti-oxidant and stabilizing properties of the original starting material. Moreover, the unreacted anti-oxidant serves as a blending agent for the relatively less soluble phosphorus oxychloride' reaction product.

Before being brought into contact with phosphorus oxychloride, the anti-oxidant material should be dried to remove any substantial amount of moisture contained therein. Phosphorus oxychloride is then slowly added to the desired antioxidant, the mixture being vigorously agitated by suitable mechanical means during the addition. During the addition period there is a copious evolution of hydrogen chloride, and for 1 this reason it is well to add the phosphorus oxychloride well below the surface of the liquid to avoid being swept out by the evolved gas and lost. When the desired amount of phosphorus oxychloride has been added, the temperature is slowly raised to around 300 to 400 F., and the mixture is maintained at this elevated temperature until there'is no further evidence of hydrogen chloride evolution, and preferably until the hydrogen chloride content of the product is less than 0.30 per cent. The resultant product, after represents the finished improvement agent of our invention and as such is ready for addition to lubricating oils without further purification.

The character of the final phosphorus-containing inhibitor will, of course, vary with the charployed in the manufacture of the anti-oxidant starting material, with the extent of absorption of the olefin, and with the amount of phosphorus subsequently introduced. All of these factors are,

however, very intimately interrelated. These are the primary factors, but it will be obvious that there are numerous secondary factors, for example the degree of purification and decolorization of the anti-oxidant starting material.

Naturally, it is to be expected that the viscosities, specific gravities and other physical characteristics of the particular phenols employed have a corresponding effect upon the product, to

some extent at least; this effect may, however,

not always hold true where the degree of olefin absorption varies over comparatively wide limits and where thepercentage of phosphorus in the final compound also varies.

When cresylic acid, ortho-cresol and metacresol and the like are used in the manufacture of the anti-oxidant, we prefer to limit the olefin absorption to around one mol per mol of the phenolic material, i. e. to. give a water-insoluble product representing roughly to per cent by volume of the original phenol, in order ultito secure inhibitors that are sufficiently the result of When the anti-oxidant starting material is prepared from phenol (CsHsOH) itself. e. 'g. per cent phenol," the degree of absorption of of C4 hydrocarbons).

The preferred olefins are those containing from three to eight carbon atoms per molecule; the

range represent advantageous and available raw materials.

After the reaction between the phenol and I olefin has been carried to the desired degree of' inabove and in the tions. The resultant water-insoluble anti-oxidant material is then preferably dried. The drying may be accomplished by filtering this mate rial through adsorbent clap or the like, the effect oxidant material to about 400 F..in suitable apparatus; this procedure dehydrates and tends to darken the anti-oxidant material.

The dry anti-oxidant may then be treated diprovement agent intended to be added to mineral oils. V

The following example will serve to illustrate our invention:

ExmrLa 1 (a) Preparation of anti-oxidant starting material 50 gallons of 90 per cent phenol were mixed with 20 pounds of 98 per cent black acid, the

' hereinabove was latter being a recovered sludge produced in washing hydrocarbon oil with .The 90 had the following properties:

Specific gravity: 60/60 F Melting point, capillary tube: "F Color: NPA 5 The phenol was placed in a suitable iron vessel and heated to a temperature of F. Olefinic may be considered as ethylene. The gas, the fore, contained 34.1 per cent by volume of unsaturated constituents.

Upon completion of the operation, there was produced a material representing 300 per cent by volume of the original phenol, i. e.

The resultant product, after removal of the caustic layer, was washed with boilcent byweight.

The final inabove, had

per cent of what appear to be gasoline-like polymers. It is a highly satisfactory anti-oxidant and gum-inhibitor. Typical physical properties of products as thus prepared are as follows:

Gravity: "API 21.6 Viscosity, SUV at 100 F.': seconds 122 Color: NPA P Dark Pour point: F 0

An anti-oxidant material prepared as set forth 'tions. That fraction distilling over at vapor tem-' peratures between 400 gated for treatment with and 550 F. .was segrephosphorus oxychloride as described below. Typical properties of fractions prepared in this manner are as follows:

(b) Preparation of final improvement agent 80 parts by weight of a fraction prepared as set forth hereinabove were treated with 20 parts by weight of phosphorus oxychloride, the product being that described in an earlier portion of this specification. The resulting material had the following properties:

Gravity: API 51 Viscosity, SUV: seconds 100 F 1176 Pour point: F Color, NPA 5.5 (dilute) Phosphorus: by wt The improvement agents prepared in accordance with our invention, and as exemplified by that given in the foregoing example, are all excellent improvement agents for addition to hydrocarbon lubricating oils and when added thereto in amounts up to 1 or 2 per cent by weight result in improved and advantageous lubricating compositions having desirable extreme-pressure characteristics.

These agents are permanently soluble in hydrocarbon oils, even in highly parafiinic oils, and are stable at ordinary temperatures. When added to lubricating oils in the amounts noted, they do not tend to settle out nor form sludge or deposition nor attack metal surfaces such as those of tin plate, terne plate, bronze or the like when packaged and stored prior to sale and use, or under circumstances of actual use in which the temperatures do not exceed, say, 250 F. On the other hand they are efiective to contribute extreme-pressure properties to hydrocarbon oils even at atmospheric temperatures.

Not only do these materials have excellent extreme-pressure properties, but their chemical nature is such that should any hydrolysis occur, the organic products of such hydrolysis are in themselves anti-oxidant materials; in this respect our products dill'er sharply from simple aryl esters of phosphorus acids, such as triphenyl phosphite, which upon hydrolysis yields highly corrosive phenol.

In our process the phosphorus content of the final product may be varied by adjusting any one or more of the following factors: (1) the character and molecular weight of the phenolic starting material, (2) the character and molecular weight of the oleflnlc starting material, (3) the degree of olefin absorption in the phenolic reaction mixture, and (4) the relative amount of phosphorus oxychloride added to the phenololefin reaction product or anti-oxidant material. All of the above factors also exert a definite influence upon the color, solubility and viscosity of the final product. The color and concentration of the anti-oxidant material have a special influence upon the color of the ultimate improvement agent.

We, therefore, regulate these various factors with reference to" each other and with regard to the starting materials available, in order to secure products of desired temperature-responsiveness, activity, solubility, viscosity, color and extreme-pressure action, within limits corresponding to the use to which thefinal compositions are to be subjected. It will also be clear that we may limit the amount of the improvement agent added to any given hydrocarbon oil, to the same "end.

Wherever the expression highly paraflinic oil is employed herein it is intended to indicate lubricating oils conforming in physical properties to oils prepared from Pennsylvania crudes;

' these highly parafiinic oils are either oils derived from Pennsylvania crudes, or oils which have beenrefined or blended to approach or even exceed the latter oils in paraflinicity. Where various materials are referred to as being soluble in suchparaflinic oils, this expression is intended to mean that such materials may be incorporated into such oilsin the amounts required, without producing any haziness or cloudiness in the appearance of the resultant compositions, at least under atmospheric temperatures and under the ordinary conditions to which such oil compositions are subjected in storage and handling prior to their actual use as lubricants.

An advantage of our process and products is that the principal ingredients employed in the manufacture of the final r-oducts, namely olefins, are cheap and available to the refiner.

The following table will serve to illustrate the eifectiveness of our improvement agents and the value of lubricating compositions containing TABLE I Oil with addition of im- Untrcated provement or] agent as prepared in Example l Make-up; Percent by wt.:

Lubricating oil, SAE l0 grade..- 100 99 Im rovement agent l 0 Genera properties: I

grungy: APtI 27.8 27 2 peel e gravi y: 60 F I Viscosity, SUV: seconds. 0 8883 0-8916 100 F 345 349 160 162 55.1 96 0. 832 420 495 +5 3-52 Appearance v Mm?! test: d Clear Clear ourna spec RPM 600 1' Rubbing speed: it. per min 40 23 Lever ad: lb 8 16 Torque: lb. it. X 10... 13 23 Unit load: lbJsq. in. 4000 8000 Lubricant temperatur Initial 86 86 Fm 113 114 Various modifications in the operating procedures mentioned hereinabove will suggest themselves to those skilled in the art. For example, we have described washing the phenololefin reaction product with water and dilute caustic soda solution to effect neutralization and removal of the acid 0r acids (e. g. sulfuric acid and sulfonic acids) remaining in the reaction mixture after the introduction of the olefins has been discontinued. Such neutralization and removal may be eifectecl in other ways, as by extraction with aqueous alcohol, contact with solid alkalis such as lime or sodium carbonate, or by contacting the reaction mix ure with solid adsorbents such as fullers earth, activated carbon, or the like.

While our improvement agents, prepared as described hereinabove, may be added to hydrocarbon oils without admixture of other substances, advantageous results may be obtained by adding these improvement agents in conjunction with other agents and particularly agents having anti-oxidant and corrosion-inhibiting properties. Especially effective composite improvement agents may be prepared by using mixtures of our improved extreme-pressure agents, described hereinabove, with inhibitors prepared by treating anti-oxidant starting materials similar to those set forth hereinabove with phosphorus trichloride, as set forth in our c0- pending application, Serial No. 99,662, filed Septcmber 5, 1936, or with phosphorus pentasulflde or a mixture of phosphorus pentasulflde and phosphorus trichloride, as set forth in our copending application, Serial No. 100,382, filed September 11, 1936. These composite mixtures may be prepared by starting material with mixtures of these phosphorus-containing reagents; for example, we may use as a reagent a mixture of phosphorus oxychloride and pho horus trichloride. In all cases, the ultimate p r' ducts should not contain more than about 5 per cent by weight of phosphorus. We have found that the results obtainable while using such composite mixtures in many cases exceed the sums of the results obtained by using the individual improvement agents alone. Thus, the materials described in the co-pending applications referred to in this paragraph are found to exert a certain stabilizaration result in products of dilferent characteristics, such products having individual advantages and utilities.

What we claim is:

1. The method of preparing an oil-soluble organic phosphorus compound suitable as an imhydrocarbon oils and efiectreating the anti-oxidant and an olefin, said product having anti-oxidant properties when added to a hydrocarbon oil, the

lated phenol, said alkylated phenol being a phenol-olefin reaction product insoluble in water and in dilute aqueous alkali solution and being a compound selected from the class consisting of alkylated phenols, and said first-mentioned reaction product containing not more than about 5 per cent of phosphorus.

4. The method of preparing an oil-soluble organic compound suitable as an improvement game compound suitable product soluble in highly paraflinic oil and containing not more than about five per cent of phosphorus 7. An improvement agent for hydrocarbon lubricating oils comprisinga reaction product of phosphorus oxychloride and an alkylated phenol, said alkylated phenol being a phenol-olefin reaction product insoluble in aqueousalkali solution and being a compound selected from the class consisting of secondary and tertiary alkylated phenols, and said firstaaaaeec mentioned reaction product containing not more than about 5 per cent of phosphorus.

8. A motor oil normally tending to produce corroslon of bearing metals of the class consisting of alloys of cadmium, silver, nickel, copper and lead, under conditions of automotive use, having added thereto a small proportion, not more than two per cent, of a reaction product of phosphorus oxychloride and an allwlated phenol, said alkylated phenol being a phenol-olefin reaction product insoluble in water and in dilute aqueous alkali solution and being a compound selected from the class consisting of secondary and tertiary alkylated phenols, and said first-mentioned reaction product containing not more than about 5 per cent of phosphorus and being present in sumcient amount substantially to retard corro-