US2214875A - Lubricating oil compositions, constituents thereof, and methods of manufacturing thesame - Google Patents

Description

nol-olefin-condensation product with phosphorus Patented Sept. 17, 1940 UNITED STATES- LUBRICATING OIL COMPOSITIONS, CON- STITUENTS THEREOF, AND METHODS OF MANUFACTURING THE SAME Troy Lee Cantrell and Jay S. Stockhardt, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania.

No Drawing. Application June 25, 1938,

Serial No. 215,920

11 Claims.

Our invention relates to the preparation of addition agents which, when added to lubricating oils in relatively small amount, produce lubricant compositions of advantageous character, to compositions containing such agents in admixture with petroleum lubricating oils, and to methods of preparing such agents.

During the past few years there have been developed a considerable number of addition agents for lubricating oils, which are effective to imiprove the lubricating value and performance characteristics of oils to which these agents are added in small amount (usually in such amount as to produce compositions having the primary physical characteristics, such as viscosity, color and the like, of the lubricating oil bases). Among these addition agents are a number of oil-soluble esters of phosphoric and phosphorous acids, for example tricresyl phosphate and triphenyl phosphite, as well as alkyl phosphates and phosphites. Most or all of these compounds possess value from one or more standpoints as addition agents for lubricants; on the other hand, most of the compounds of this type which have been developed in the past are also subject to definite disadvantages or limitations in use. The phosphates, in general, are stable and efiective.

to increase the load-carrying properties of petroleum lubricants to which they are added. They are usually designated as mild EP agents," for the reasonthat they impart some extreme pressure characteristicsto lubricating oils. The phosphites, in general, are on the other hand somewhat less stable and less efiective to increase load-bearing characteristics, but when added to certain lubricating oils, possess the property of inhibiting corrosion of sensitive metal alloys, particularly under high-temperature conditions. The aryl and alkaryl phosphates and phosphites have definite advantages. However, the less highly alkylated-members of this group possess limited solubilities in petroleum lubricating oils, especially in the more highly refined and more highly paraflinic oils of highest grade.

In the copending application Serial No. 100,786, filed September 14, 1936, of Cantrell 8r Turner, there'are set forth and described lubricating oil compositions comprising petroleum lubricating oils in admixture with a relatively small amount of an addition agent prepared by reacting a phe-' 'oxychloride. This agent, constituting primarily an alkylated aryl phosphate, represents, from: most standpoints, a highly useful and advantageous addition agent for lubricating oils. Itsability to contribute extreme-pressure characteristics is good, it is highly soluble in even the most highly refined lubricating oils, it is stable, and lubricating oil compositions containing relatively small amounts of this agent withstand oxidation, as measured by the commonly employed Sligh oxidation test, to a satisfactory extent. However, this reaction product of phosphorus oxychloride and phenol-olefin condensation product tends normally to be too dark in color for general use; the addition thereof to lubricating oils, even in small amounts up to 2 per cent by weight of such oils, results in an undesirable darkening or discoloration. It is possible to obviate this to'some extent by subsequently refining methods, but that involves additional manipulation and expense and is not wholly satisfactory.

We have found that a new and improved addition agent for petroleum lubricating oils can be prepared byreacting a phenol-olefin condensation product or alkylated phenol with phosphorus oxychloride, in the presence of a small or catalytic amount of phosphorus sesquisulfide (P483). The reaction product thus obtained is exceptionally light in color, stable, highly efiective as an extreme pressure agent, having a mild I inhibiting value with respect to the corrosion of sensitive metal alloys, such as cadmium-silver, copper-lead and cadmium-nickel bearing alloys, and-when added to petroleum lubricants, produces lubricating compositions resistant to oxidation and yielding low Sligh values. This product is also exceptionally useful as a means of preventing pisto'n-ring sticking in internal-combustion engines, and for that purpose may be added either to the crankcase lubricant or to the fuel supplied to such engines; in the latter case,

. amountsof as little as 0.001 per cent of the fuel are efiective.

Where corrosion of sensitive metal alloys, in bearings or the like, is a problem, our invention also contemplates the addition to a lubricating oil of a relatively small amount of a mixture predominating in the light-colored phosphate reaction product of our invention, in admixture with a relatively small amount of a phosphite ester, preferably an alkylated aryl phosphite such as the product obtained by reacting a phenololefin condensation product or alkylated phenol with phosphorus trichloride. Such an admixture of addition agents is especially advantageous for the purpose of contributing extreme pressure, anti-ring sticking and anti-corrosion properties to lubricating oils, when added-thereto.

The raw material employed in preparing our improved addition agent is, as has been set forth hereinabove, a condensation product of a phenol and an olefin, and constituting primarily a highly alkylated phenol or a mixture of such compounds.

Such alkylated phenols are in themselves powerful antioxidants andrepresent, partly on account of their insolubility in water and dilute alkali solution, desirable addition agents for petroleum lubricating oils. Such antioxidants and methods of preparing the same are disclosed, for example, in the prior copending application of Stevens & Gruse Serial No. 702,258, filed December 13, 1933 (now Patent No.. 2,061,111, patented Nov. 17,

1936), and in the copending applications of Troy Lee Cantrell, Serial No. 64,413, flled February 17, 1936, and Serial No. 99,488, filed September 4,

'1936 (nowPatent No. 2,149,759, patented March 7, 1939).

effective to promote alkylation of the phenolic material. Various phenolic materials maybe employed, for example phenol itself, any one or more of the cresols, and certain of the xylenols.

Ordinary phenol and para-cresol are most ad-.

vantageous.

The alkylating material may be any olefin ef-.

' 'fective, under the conditions employed, to produce alkylation products in which the alkylations are of secondary or preferably tertiary type; olefins having 3 to 8 carbon atoms per molecule are useful? Butylenes, amylenes and refinery gases or distillates containing such olefins are especially suitableas oleflnic starting materials. Ordinarily we prefer to alkylate phenol or para- :cresol or a phenolic mixture containing either or both of these'materials with refinery gases containing isobutylene, in the presence of from 1 to 10 per cent of sulfuric acid having a strength I of T60 per cent or higher, and to continue the alkylation until the phenol undergoing reaction has increased in weight to from 2 to 4 times the weight of the original phenolic material. The

product thereby obtained is thenwashed with water and with caustic soda solution not exceeding 15 per cent by weight NaOH, or an" alkaline agentofequivalentstrength. t,

It is also advantageous to distil theraw condensation product before reactingthe alkylated phenol material thereby obtained with the phos-.

" phorus-containing reagent. to secure a relatively concentrated heart cut" amounting to from 60 to 70 per cent of the crude raw material: 0

- Although some alkali-insoluble secondary type alkylated phenols may be present, the constituents most desired are dior tri tertiary alkyl phenols, of which 2,4,6-tri;tertiary-butyl phenol and 2,6-di-tertiary-butyl-4-methyl phenol are examples. However, the exact constitution of the materials thus prepared'will, of course; vary with the nature of the materials employed, and

especially where the phenolic and oleflnic raw materials are crudef'or mixed in character, the. final product is to a certain extent obscure in constitution, and our invention is not limited to any particular chemical compound, beyond the requirement that it constitute a condensation. product of a phenol and an olefin, insoluble in' water. and in per cent aqueous NaOH solution or the equivalent thereof.

I As aforesaid, 't'h'e'addition agent of our invention is prepared by reacting a condensation p odnot or antioxidant of the character described products containingfrom 4 to 6 per cent by weight. of phosphorus are, however, most advantageous; these. are sufliciently active, and they are more soluble in highly paraflinic oils and more stable in storage than products containing higher percentages of phosphorus.

In general, the alkylated phenol raw material is treated with from 5 to 40 per cent by weight of phosphorus oxychloride and with from 0.1 to 2.0 per cent by weight of phosphorus sesquisul-' fide, but for the manufacture of inhibitors of the. highest grade, it is desirable toemploy from to per cent by weight of phosphorus oxychloride and from 0.1 to 0.25 per cent of phosphorus sesquisulfide (assuming the antioxidant starting material to be relatively concentrated and pure in character). I 1

In effecting the reaction, the antioxidant starting material is flrst dried to remove any sub-. stantial amount of moisture which may be present therein, and the desired amount of P453 is then added to the moisture-free antioxidant followed by the addition of the required amount of P0013. The mixture is vigorously agitated by suitable means as the addition of. the phosphoruscontaining reagents progresses. During the addition period, there is a copious evolution of HCl; and for this reason it is well to add the pliosphorus-containing reagent well below the surface of the liquid to avoid loss of this reagent in the evolved gas. When the requisite amount of phosphorus reagent has been added, the temperature of the mixture is slowly raised to a temperature of about 550" F., and the mixtureis maintained at. this elevated temperature until there is no further evolution of HCl, and preferably-until invention.

In the preparation of the material of this ex- 1000 parts by weight of this material were then reactedwith 262 parts by weight of POCla-and ample there was employed a phenol-olefin 'antioxidant, prepared in the manner set forth hereinabove, and having the following physical prop, erties:

Gravity: API l 16.1 Viscosity, SUV 100 F 63.4 Flash, 00 F" 85 Fire, 00 T--- 163 Pour F -30 Color, NPA- 1.0 Distillation, gasoline, method:

Over'point 381 End point 528- 10%atF- 41':- so% at F, 4'12 90% at T a 508 3partsby weight of P483, the temperature .of the mixture being raisedto 5505* 16. after the addition of the phosphorus-containing reagent, and the mixture being maintained at this temperature for five hours.

There were obtained 987 parts by weight of a material having the following physical properties:

It will be observed that in adding material of this character to a lubricating oil, the amount added will vary inaccordance with the degree of effect desired and the purposes to which the oil is to be put. For crank-cases and engine oils amounts of from 0.1 to per cent, usually around 1 per cent, by weight are suitable, whereas in the preparation of gear lubricants-considerably larger amounts up to 25 per cent by weight on the lubricant base may be employed.

In a typical example, one part by weightof alkaryl phosphate, prepared as set forth in- Example I, was added to 9.9 parts by weight of a highly refined lubricating oil of 60 SAE classification. The thereby compounded oil was found to be greatly increased in its ability tostand high-bearing loads and to be substantially improved with respect to its tendency to develop a temperature increase in the lubrication of bearings maintained under moderately highbearing pressures. Whereas the oil alone failed to carry a 16-pound load for 15 minutes on the Almen testing machine, the compounded oil successfully withstood a lever load in excess of 32 pounds, representing a unit bearing load of 16,000 pounds per square inch for a time in excess of 15 minutes.

The compounded oil was almost exactly identical with the initial 011 base in respect to specific gravity, viscosity, flash and fire test, and color. It had a carbon residue of 0.33 per cent as compared with 0.36 per cent for the uncompounded oil. The Sligh oxidation number of the initial oil was only very slightly increased (from 1.0 to 2.0) by the addition of the improved agent and the neutralization number was likewise only very slightly increased.

Increasing the relative amount of phosphorus sesquichloride employed tends to yield a product somewhat more effective, when added to petroleum lubricating oil, in increasing the load-bearing characteristics of the oil, but having'a higher Sligh oxidation number. Thus, a material simi- It will therefore be evident that the relative amount of P483 employed will be governed by whether high extreme-pressure" characteristics or high resistance to oxidation constitutes the dominant factor in determining the value of the final lubricant composition.

As indicated hereinabove, the alkaryl product of our invention may be advantageously em-' ployed in admixture with a relatively small amount of an oil-soluble phosphite ester, for exreacting the phenol-olefin condensation product described hereinabove with phosphorus trichloride, as set forth and described in the prior co- I pending application of Cantrell & Turner, Serial No. 99,662, filed September 5, 1936. We have successfully employed mixtures containing these phosphate and phosphite materials in proportions ranging from 4:1 to 9:1, respectively, and in particular have found that the addition of 0.36 per cent of the phosphate inhibitor of our invention plus 0.04 per cent by weight of the aforesaid alkaryl phosphite reaction product to a petroleum lubricating oil yielded a lubricant composition extraordinarily free from ring-sticking and bearing corrosion tendencies, as compared with the uncompounded oil.

The advantages of our additionagent are evident in comparison with tri-cresyl phosphate, which is perhaps the most widely used phosphorus-containing addition agent. As compared with tri-cresyl phosphate, our addition agent is simpler and easier to prepare, requiring no final ample an alkylated. aryl phosphite prepared by distillation, it is a more effective extreme-pressure agent than tri-cresyl phosphate, it is more soluble in hydrocarbon oils, particularly the high refined oils, and it is more stable in the presence of water. It also possesses a more effective inhibiting action with respect to corrosion-sensitive bearing alloys than is true of tri-cresyl phosphate, although, as has beenindicated, it is less effective for this purpose'than .most phosphites, and is best employed (where-this problem is serious) in admixture with a relatively small amount of a phosphite of similar character. Our addition agent is also of such character, when properly prepared, as to enable oils compounded the. claims hereinafter made.

What we claim is:

1. The method of preparing an oil-soluble organic compound suitable as an improvement agent for hydrocarbon oils, which comprises reacting an olefin and a phenol in the presence of a catalyst and treating at least a portion of the resultant product with phosphorus oxychloride in the presence of a catalytic amount of phosphorus sesquisulfide.

2. The method of preparing an oil-soluble organic compound suitable as animprovement agent for hydrocarbon oils, which comprises treating a phenol selected from the class consisting of water-insoluble secondary and tertiary alkylated phenols with phosphorus oxychloride in the presence of a relatively small amount of phosphorus sesquisulfide, the amount of the phosphorus-containing reagents being such as to effect the formation of a final phosphate inhibitor product containing from 1 to 10 per cent of phosphorus.

3. The method of preparing an oil-soluble organic compound suitable as an improvement agent for hydrocarbon oils, which comprises reacting a phenol selected from the class consisting of secondary and tertiary alkylated phenol with phosphorus oxychloride in the presence of a catalytic amount of phosphorus sesquisulfide, and heating the resultant mixture until the chlorine 4 w content of the product is less than 025 per cent.

4. The method of preparing an oil-soluble organic compound suitable as an improvement agent for hydrocarbon oils, which comprises reacting an olefin and a phenol in the presence of sulfuric acid, neutralizing the resultant product with dilute alkali solution, distilling the neutralized alkali-insoluble product to recover a fraction at intermediate boiling range, and reacting said fraction with a mixture of phosphorus tively small amount of phosphorus sesquisulflde,- said agent containing from 1 to-10 per cent of phosphorus and not more than 0.25 per cent of chlorine. t

1. An improvement agent for hydrocarbon oils comprising a mixture of products obtained by reacting water-insoluble tertiary alkylated phenol with amixture of phosphorus oxychlorid and a relatively small amount of phosphorus sesquicollide, and with phosphorus trichloride, respecs tively.

8. The method of obtaining a light-colored phosphate reaction product of a water-insoluble. tertiary alkylated phenol and phosphorus oxychloride, which comprises conducting the reaction in the presence of a quantity ofphosphorus sesquisulflde relatively small with re-' spect to the quantity of phosphorus oxychloride present. v

9. In combination, a small amount of a light colorerL reaction product of a water-insoluble tertiary alkylalted phosphate, phosphorus oxychlorlde and a relatively small amount of phosphorus sesquisulflde, and a hydrocarbon oil.

10. The method of prevention or reducing ring- 'stic king in internal combustion engines, which comprises introducing into the cylinders of such an engine a small quantity of an aryl phosphate comprising theireaction product of a water-."

insoluble tertiary alkylated phenol, phosphorus oxychloride and a relativelysmall amountot phosphorus sesquisulflde.

11. An improved lubricant for internalcom bustion engines comprising a major amount-oi a hydrocarbon lubricating oil having incorporated therein a' minor-amount of an aryl phosphate reaction product of a water-insoluble tertiary alkylated phenol, phosphorus oxychloride and a relatively small amount ofphosphorus sesquisuliide;

- TROY- LEE CAN'IREIL'. JAYS. STOCKHARDT.