US2461961A - Lubricating composition - Google Patents

Description

Patented Feb. 15, 1949 2381,96). LUBnIcA'riNG COMPOSITION No DrawingJ Application December 29, 1945, Serial No. 638,464

14 Claims.

This invention relates to lubricating oil addition agents designed to improve the lubricating properties of lubricating oils for use under conditions of severe service such as those encountered in Diesel engines, and the like, and to lubrieating oils containing these addition agents.

Primarily, the object of this invention is to produce, for use under such severe service conditions as are encountered in Diesel engines, lubricating oils which will be non-corrosive to corrosion-sensitive bearings, such as the copper-lead or cadmium-silver type, and which will also avoid the deposition of lacquer and varnish-like materials upon pistons and overcome carbon deposition behind the rings.

Other objects of this invention will be apparent from the description contained hereinafter.

It is well known that ordinary mineral lubricants are effective only within certain limits of engine operating conditions and when these limits are exceeded deterioration of the lubricating oils results causing undesirable ring sticking, bearing corrosion, sludge formation, piston lacquering, and the like. Addition agents have been developed and used in lubricating oils to minimize this deterioration and to reduce its deleterious effects if it does occur.

Addition agents which have been proposed for the improvement of lubricating properties of lubricating oils are many in number. In general these agents are designed to function in some specific manner; for example, an addition agent to which is attributed detergent properties is one which tends to keep pistons, rings and valves free of lacquer and varnish-like deposits. Oil-soluble metal salts of sulfonic acids are perhaps the most generally used addition agents to improve the detergent properties of a lubricating oil and their use is well known in the art. Prevention of bearing corrosion is another specific function for which lubricating oil addition agents have been designed. Addition agents which perform this anti-corrosion function include phenolic compounds, metal salts of the reaction products of a sulfide of phosphorus and an alcohol, metal salts of the reaction products of a sulfide of phosphorus and a hydrocarbon,'such as those disclosed in United States Patent No. 2316,082 to Loane et al., and many others.

The present invention resides in lubricating oils, preferably mineral lubricating oils, containing oil-soluble metal salts of a material prepared by first reacting a hydrocarbon with a sulfide or oxide of phosphorus, a mixture of phosphorus and sulfur or phosphorus and oxygen, and subsequently treating the product so obtained with an alcohol, phenol, mercaptan or thiophenol. The first reaction step of the above process is believed to take place with the formation of a bond linking phosphorus to one or more of the carbon atoms of the hydrocarbon and thus can be said to result in the formation of a carbon-phosphorus bond. The product obtained by reacting a hydrocarbon with a sulfide or oxide of phosphorus or with phosphorus in the presence of sulfur or oxygen will be referred to herein as a substituted acid of phosphorus having an organic substituent attached to phosphorus by a carbon-phosphorus bond. The reaction product of the substituted acid of phosphorus with an alcohol, phenol, mercaptan or thiophenol will be referred to herein as an ester of a substituted acid of phosphorus having an organic substituent attached to phosphorus by a carbon-phosphorus bond. Although the organic substituent is believed to be attached to phosphorus by a carbon-phosphorus bond it is to be understood that the invention is broad enough to cover organic substituted phosphorus compounds which are produced by the reaction steps herein described regardless of the type of linkage actually obtained.

We have discovered that the performance of internal combustion engines under severe service conditions can be markedly improved by the use of'a lubricating oil to which has been added a small amount of an oil-soluble metal salt of a product obtained by first reacting a hydrocarbon with a sulfide of phosphorus and then treating the product so obtained with a compound of the group consisting of alcohols, phenols, mercaptans and thiophenols. This additive appears to markedly improve the corrosion characteristics of the mineral lubricating oil and also appears to impart detergency to the oil.

We have discovered also that the lubricating properties of a lubricating oil can be markedly improved by the addition of a small amount of an oil-soluble metal salt of the described ester of a substituted acid of phosphorus having an organic substituent together with small quantities of other lubricating oil addition agents. Other addition agents which may be used in conjunction with the products of the present invention include those generally classified as detergent additives such as the oil-soluble metal salts of sulfonic acids, particularly petroleum sulfonic acids; oil-soluble metal salts or soaps of fatty acids, or substituted fatty acids such as dichlorostearic acid, phenyl stearic acid and the like: oil-soluble metal salts or soaps of rosin acids such as abletic acid, hydrogenated rosin acids and the like; oil-soluble metal salts or soaps of acids produced by oxidizing hydrocarbons or hydrocarbon fractions such as paraifin wax, parafllnic lubricating oil fractions and the like. Other addition agents which may be employed include oil-soluble metal salts of phenols and particularly alkyl or cycloalkyl substituted phenols such. as those having more than about 12 carbon atoms per molecule; oil-soluble metal salts of phenol sulfides or alkyl or cycloalkyl substituted phenol sulfides and particularly those having alkyl substituenis containing at least 4 carbon atoms; oil'- soluble metal salts of the reaction products formed by reacting a sulfide or oxide of phos- .phorus with an alcohol or with a phenol; oilsoluble metal salts of phosphonic or phosphinic acids obtained by reacting elemental phosphorus with hydrocarbons as described in United States Patent No. 2,311,305 to Ritchey and, in fact, many others.

In preparing lubricating oils it is sometimes desirable to add in addition to the oil-soluble metal salt of a substituted ester of phosphorus containing an organic substituent two other addition. agents. Thus the invention comprises lubricating oils containing the described phosphorus ester compound as the sole addition agent as well as lubricating oils containing the phosphorus ester compound with one or two of the other addition agents described. Preferably at least one of the additives will be of the detergent type.

A particularly desirable oil-soluble metal salt of the ester of a substituted acid of phosphorus having an organic substituent to be used in the practice of our invention may be prepared by first reacting a hydrocarbon with a sulfide of phosphorus, treating the product so obtained with an alcohol to produce the ester, and then preparing a metal salt of this reaction product. Thus hydrocarbons such as alkyl substituted benzenes, alkyl substituted naphthalenes, and the like, or various petroleum fractions such as those described hereinbelow which may be obtained in the solvent extraction of lubricating oil distillates are reacted with from about 3% to 50%, and preferably from about to 20% by weight of a sulfide of phosphorus, preferably phosphorus pentasulfide, for one to twelve hours at temperatures of from about 200 F. to 600 F., and preferably at about 400 F. This reaction proceeds with the evolution of hydrogen sulfide and is generally continued until such evolution ceases. The reaction product is then treated with an alcohol in such a manner that one or more of the acidic groups of'the reaction product is neutralized by the process of esteriflcation. Thus ethyl alcohol or the like, may be added to the reaction product maintained at a temperature of about 100 F. to 150 F. and the mixture stirred for a period of one to twelve hours. In general the mixture becomes more homogeneous as the reaction proceeds and the reaction may be considered to be compete when homogeneity results. In some cases it is advantageous to employ a solvent or thinner such as a low boiling gasoline or naphtha fraction to reduce the viscosity of the reaction mixture and to facilitate stirring, temperature control, etc.

The amount of alcohol to be used in treating the phosphorus sulfide hydrocarbon reaction product varies with the molecular weight of the hydrocarbon used, the amount of phosphorus sulfide which reacts with the hydrocarbon and the molecular weight of the alcohol. In general satisfactory results have been obtained when the ratio of molecules of alcohol to atoms of combined phosphorus isabout l to 1. An excess of alcohol may be added and after the reaction iscomplete the unreacted alcohol can then be removed such as by distillation. It is not always necessary-or even. advisable to use an excess of the alcohol or other esteriiying agent. This is particularly true in those cases in which the unreacted agent would be difficult to remove.

The reaction product obtained in this second step, i. e., the ester is acidic and may be neutralized with basically reacting metallic compounds. The desired oil-soluble metal salt is usually prepared by direct neutralization of the esterified product with a basic compound of the desired metal such as the oxide, hydroxide, carbonate. or in some cases the metal itself, may be used. The salt may also be prepared by first neutralizing the reaction product with a hydroxide, oxide or carbonate of an alkali metal, such as sodium or potassium, and then preparing the desired metal salt from the alkali metal salt by metathesis. For example, a heavy metal salt such as the nickel salt, may be prepared by metathesizing the sodium salt of the reaction product with a nickel salt, such as nickel chloride or nickel sulfate, using conditions well known in the art for effecting reactions of this type. When carrying out the neutralization of the reaction mixture with a metal oxide, hydroxide or carbonate it is sometimes advantageous to dilute the reaction mixture with about an equal volume of a lower boiling hydrocarbon or hydrocarbon fraction, such as a low boiling gasoline or naphtha fraction, or the like, and to use a small amount of water along with the metal oxide, hydroxide or carbonate. Under such conditions and particularly it slightly elevated temperatures are used the neutralization proceeds to completion in a rather short period of time.

While we prefer to use the procedure described hereabove for the preparation of the products of this invention it may be modified to give equally satisfactory results. For example, instead of using an alcohol, phenol, mercaptan, or thiophenol in the second step of the reaction we may employ a metal salt of one of these compounds, such as a metal alcoholate, metal phenate, and the like.

When these metal salts are used the product obtained is the corresponding metal salt of the ester of a substituted acid of phosphorus having an organic substituent. Thus if sodium ethylate is employed in the second step of the reaction the product obtained will be the same as that which would be obtained by, using ethyl alcohol in the second step followed by eutralization of the ester with sodium hydroxide, oxide or carbonate. The reaction products obtained when metal alcoholates, phenates, etc., are employed may be used as lubricating oil addition agents without further treatment or they may be converted into other metal salts by methathesis, as described hereinabove.

sulfides of phosphorus which may be employed in the process of this invention include phosphorus pentasulfide, phosphorus trisulfide and/or mixtures of these sulfides. Oxides of phosphorus which may be employed include phosphorus pentoxide, phosphorus trioxide and/or mixtures of these oxides. In place of phosphorus sulfides or oxides we may also employ mixtures of elemental phosphorus and sulfur.

Hydrocarbons which may be reacted with suifides or oxides of phosphorus according to the process of our invention to produce the substituted acids of phosphorus having an organic substituent, are many in number. The organic substituent is a hydrocarbon radical derived from the hydrocarbon or mixture of hydrocarbons employed. Petroleum fractions, such as extracts or raifinates obtained in the solvent treating of lubricating oils, may be employed as well as various other hydrocarbons such as olefins, olefin polymers, aromatic hydrocarbons, for example, alkyl or cycloalkyl substituted benzenes, napthalenes, anthracenes and higher molecular weight condensed ring aromatic compounds, in which the substituent or substituents each contain more than four carbon atoms and preferably contain six or more carbon atoms. Of particular value as a starting material for the preparation of the .products of our invention is a so-called intermediate oil" fraction of petroleum hydrocarbons obtained in the solvent refining of lubricating oils. The preparation and properties of this intermediate oil are fully described in our copending application, Serial No. 595,480, filed May 23, 1945.

The method of preparation of an intermediate oil may be illustrated in the following manner. A lubricating oil fraction, prepared from a waxy Santa Fe Springs (California) crude oil by vacuum distillation in the presence of superheated steam, was dewaxed by diluting with 4 volumes of liquid propane, cooling to 50 F. and filtering to remove the wax. The propane was then removed by a topping distillation. The dewaxed fraction was extracted with 3 volumes of phenol at about 150 F. to produce, after removal of the phenol, a phenol raflinate amounting to about 45% by volume of the dewaxed fraction and a phenol extract amounting to about 55% by volume of the dewaxed fraction. This phenol extract was further treated with 7 volumes of furfural at about 150 F. to produce, after removal of the furfural, a furfural extract amounting to about 65% by volume of the phenol extract and a furfural rafilnate amounting to about 35% by volume of the phenol extract. This furfural raflinate is the material to which we have given the name'of intermediate oil.

' The characteristics of this furfural raffinate are given below together with the characteristics of the phenol railinate, phenol extract and furfural extract.

Phenol Phenol Furfural Furi'ural Raflinate Extract Rufiinate Extract Gravity, API 28, 7 19.7 Viscosity, S. U.

S. at-

100 F 729 1 110.000 3,800 1 1, 400, 000 130 F 305 12, 354 87.197 210 F 73. 1 394 131 919 Oonradson carbon, percent residue 0.03 2. 9 1. 4 5. 8 Iodine No. (Hanus) Mg. Iodine absorbed per g 0.62 3. l 1. 2 24, 4 Sulfur, percent 1.04 0.97 L05 Carbon, percent 86. 00 87. 57 85. 40 86. 82 Hydrogen, percent 14. ll 10. 87 12 33 9. 93 Viscosity Index. 90 270 $3. 9 -820 Viscosity Gravity Constant based on viscosity at 210 F 0.806 0.864

1 Extrapolated.

Compounds which may be used to esterify the n-propyl, isopropyl, butyl, hexyl, octyl.'decyl,

lauryl, cetyl, cyclohexyl, methylcyclohexyi aicohols; aliphatic alcohols containing an aromatic substituent such as benzyl alcohol, phenylethyl alcohol and the like; and aliphatic and alicyclic polyhydroxy alcohols, such as ethylene glycol, propylene glycol and other polymethylene glycols, glycerine and the like.

(b) Phenols, such as phenol and alkyl substituted phenols such as cresol, p-tertiary-amyl phenol, p-tertiaryoctyl phenol, diamyl phenol. Alpha and beta-napthols, and the like. Polyhydroxy phenols and alkyl substituted polyhydroxy phenols such as hydroquinone, catechol, resorcinol, pyrogalloi, tertiary butyl catechol and the like.

(c) Mercaptans, including the aliphatic and alicyclic mercaptans, such as the methyl, ethyl. propyl, lauryl, cyclohexyl and methylcyclohexyl, mercaptans,

(d) Thiophenols, such as thlophenol, thiocresol, and other thio phenols corresponding to the phenols listed above.

Compounds of the above types and their metal salts which may also be used may be represented by the formula R-X-H, where R represents an alkyl, cycloalkyl, aryl, alkaryl or aralkyl radical, X represents oxygen or sulfur, and H represents hydrogen or the hydrogen equivalent of a metal.

Oil-soluble sulfonates which may be used in conjunction with the products of our invention include the metal salts of substantially any oilsoluble sulfonic acid. Suitable sulfonic acids are obtainable on the market under various trade names generally in the form of their sodium salts. For example, Sonneborn Sons, Inc., of New York city, markets such a material under the name Petronate which contains about 60% by weight of sodium sulfonates and 40% by weight ofv mineral oil. The sodium salts may be used directly or they may be converted into other metal salts by processes of metathesis which are well known in the art.

If desired the oil-soluble metal salt of a sulfonic acid may be prepared by direct sulfonation of a suitable material, with fuming sulfuric acid,

gaseous sulfur trioxide, chlorosulfonic acid, etc.,'

to form oil-soluble sulfonic acids followed by the preparation of metal salts either by direct neutralization with a basic metal compound, such as the oxide, hydroxide or carbonate, or by neutralization with a metal oxide, hydroxide or carbonate followed by the preparation of the desired metal salt by metathesis.

Oil-soluble metal salts of phenols which may be used in the practice of our invention include the oil-soluble metal salts of many phenolic materials such as those of alkyl or cycloalkyl substituted phenols having more than about twelve carbon atoms per molecule as well as phenol sulfides of the alkyl hydroxy phenyl thio ether type. Thus metal phenates such as those described in United States Patent No. 2,281,401 to Wilson and United States Patent No. 2,344,988 to Kavanagh et 2.1., may be employed. Phenol sulfides of the above type which may be employed are described in United States Patent No. 2,139,766 to Mikeska et al., and similar compounds together with their method of preparation are described in United State Patent No. 2,139,321 to Mikeska et a1.

ganic acids produced by oxidizing hydrocarbons or hydrocarbon fractions are described in United States Patent No. 2,270,620 to Bray. The synthetic organic acids used in the preparation of oil-soluble metal salts are preferably obtained by oxidizing relatively high molecular weight hydrocarbon fractions suchv as highly paraflinic lubricating oil fractions and the like or paraflln wax. The acids so produced may be converted into the vmetal salts directly or they may be chlorinated and the chlorinated acids converted into their metal salts. Preferably the acids will contain in excess of ten carbon atoms per molecule.

Suitable oil-soluble metal salts of acids produced by the reaction of a phosphorus sulfide or oxide with an alcohol or with a phenol are preferably those alkyl, aryl, or aralkyl phosphoric or thiophosphoric acid salts prepared by the reaction of P285 or P205 on an alcohol or phenol. The method of preparing these salts is fully described in the Freuler United States Patent No. 2,364,284. The preferred alcohols and phenols are the monohydroxy organic compounds where the organic group comprises an alkyl, cycloalkyl, aryl, aralkyl or alkaryl radical.

Metals which may be used to form the desired metal salts or soaps of each of the additive materials described hereinabove, including the metal salts of the esters of substituted acid of phosphorus having an organic substituent, include the alkaline earth metals, calcium, strontium, barium and magnesium, and the polyvalent metals zinc, nickel; aluminum, lead, manganese, mercury, copper, iron, tin, chromium, bismuth and thorium. In some instances the alkali metal salts may be employed such as the sodium, potassium or lithium salts.

The products of this invention may be em ployed to improve the lubricating qualities of any lubricating oil, but we prefer to use mineral lubricating oils, especially mineral lubricating 0115 having a viscosity index, as defined by Dean and Davis, Chemical and Metallurgical Engineering,

vol. 36, page 618 (1929), above about 75 such as those produced by solvent treating parafiinic base stocks.

In preparing lubricating oils containing an oilsoluble metal salt of the reaction product of this invention the preparation of the metal salt employed should be such that the phosphorus content of the oil due to the presence of said metal salt will be in the order of 0.01% to about 0.5% by weight, and preferably in the range from about 0.05% to 0.2% by weight. If a second addition agent, i. e., sulfonate, phenate, etc., is present it should constitute between about 0.1% and about 3.0% or even. as much as 5.0% by weight, and preferably between about 0.5% and 2.5% by weight of the finished oil.

The method employed for determining the phosphorus content of additives and finished lubricating oils is a standard analytical procedure consisting of first converting the phosphorus in a weighed quantity of the material to be analyzed to the phosphate form by oxidation with sodium peroxide in a Parr bomb and then finishing the analysis according to the procedure given by Kolthoff and Sandell, Textbook of Inorganic Analysis (1936), page 676, for the determination of phosphorus in steel wherein the phosphorus is weighed as magnesium pyrophosphate.

The metal salts which we employ to prepare a high quality lubricating oil are oil-soluble and require only simple mixing with a lubricating oil to obtain solution. However. the blending is usually effected at slightly elevated temperatures in the range of 100 F. to 200 F. in order to facilitate solution and mixing of the addition agent or agents with the lubricating oil.

The lubricating compositions of our invention have been evaluated in'a Lauson single cylinder engine operated in such a manner that the lubricating oil is subjected to severe service conditions. In carrying out this Lauson engine test the engine is operated for a total of sixty hours under a load of about 3.5 horsepower with a coolant temperature of about 295 F. and an oil temperature of about 280 F. This test is employed to determine the lacquering and corrosion tendencies of the oil. At the end of the test the cleanliness'of the englue is observed and given a numerical detergency rating between 0% and 100%, where 100% indicates a perfectly clean engine. Thus a detergency rating of 100% would indicate that there were substantially no lacquer or varnishlike deposits within the engine. The corrosivity of the oil is measured by determining the loss in weight of corrosion sensitive copper-lead bearings after twenty, forty and sixty hours of operation. In those cases in which corrosion was ex:- tremely severe and there appeared to be danger of engine failure due to excessive corrosion of the copper-lead bearings as indicated by an examination made at the forty hour period, these bearings were replaced with babbitt hearings in order to complete the test.

An example which illustrates our invention in one form is given below. It is to be recognized, however, that many variations may be made within the scope of the invention.

To 393 grams of the intermediate oil, described hereinabove as being a particularly desirable hydrocarbon for use in the process of this invention, was added 44 grams of phosphorus pentasulfide and the mixture heated with stirring at a temperature of about 400 F. for two hours. The reaction mixture was diluted with about an equal volume of a parafllnic hydrocarbon solvent,

having'a boiling range of 140 F. to 200 F., and filtered. To about one-half of the resulting filtrate was added a 180 ml. portion of ethyl alcohol and the mixture heated on a steam bath with stirring for about two hours at a temperature of about 160 F. A ten gram portion of calcium hydroxide was then added to the reaction mixture and the mixture slowly heated to about 280 F. to remove unreacted ethyl alcohol, the parafllnic hydrocarbon solvent and water formed in the reaction. About an equal volume of the parafllnic hydrocarbon solvent was again added and the solution filtered through finely ground diatomaceous earth to remove unreacted calcium hydroxide. The final product was obtained by heating the filtrate to 270 F. to remove the parafilnic hydrocarbon solvent and amounted to 177 grams of material having a phosphorus content of 2.35%.

The efficacy of this product in preventing corrosion of alloy bearings of the copper-lead type and in preventing excessive lacquering of engine parts was demonstrated by a Lauson engine test on a lubricating composition, having a phosphorus content of 0. 2%, and containing 5.3% by weight of the product obtained above and 94.7% by weight of a mineral lubricating oil in the SAE 30 range having a gravity of 285 A. P. 1., a viscosity of 746 Saybolt Universal at F., and a Cu-Pb bearing replaced by Babbitt bearing at 40 hours due to excessive corrision.

The foregoing description of our invention is not to be taken as limiting since many variations may be made by those skilled in the art'without departing from the spirit or the scope of the following claims. t We claim:

1. A lubricating composition consisting .essentially of mineral lubricating oil and a small amount, suflicient to impart anti-corrosion properties to said oil, of an oil-soluble metal salt of an acidic reaction product obtained by reacting a lubricating oil fraction of petroleum with a compound of phosphorus of the class .of phosphorus metal salt of an acidic reaction productobtained by reacting a lubricating oil fraction of petroleum with phosphorus pentasulfldeat a. temperature of about 200 F. to about 600 F. to produce a sulfur-containing substituted acid of phosphorus 1 1 10 having an organic substituent and subsequently esterifying thereaction product with an alcohol said small amount of said oil-soluble metal salt being sufiicient to impart a phosphorus content of between about 0.01 and about 0.5% by weight.

7.. A lubricating composition according to claim 5 containing also a, small amount, between about 0.1% and about 3.0% by weight of an oil-soluble metal phenate.

8. A lubricating composition as in claim- 1 in which the lubricating oil fraction of petroleum is sulfides and phosphorus oxides at a temperature between about 200 F.' and about 600 F. and re- 4. A lubricating composition according to claim 5 in which both oil-soluble metal compounds are alkaline earth metal compounds.

5. A lubricating composition consisting essentially of mineral lubricating oil and between about 0.1% and about 3.0% by weight of an oil-soluble metal detergent and a small amount, sufl lclent to impart antiacorrosion properties to said 011, of an oil-soluble metal salt or an acidic reaction product 'bbtained by reacting alubricating oil traction of petroleum with a compound of ph0s-. phorus oi the class of phosphorus sulfides and phosphorus oxides at a temperature between about 200v F. and about 600 F. and reacting the product with an esterifying agent saidv small amount oi said oil-soluble metal salt being sufllcient to impart a phosphorus content of between about 0.01% and about 0.6% by weight.

lubricating oil extract.

9. A lubricating composition as in claim 1 in which the lubricating oil fraction of petroleum is a lubricating oil raflinate.

10. A lubricating composition as in claim 1 in which the esterifying agent contains an OR group.

11. A lubricating composition as in claim 1 in which the esterifying agent contains an SH group. 12. A lubricating composition asin claim 1 in which the esterifying agent is a phenol.

13. A lubricating composition as in claim 1 in which the esterifying agent is a mercaptan.

14. A lubricating composition as in claim 1 in which the lubricating oil fraction of petroleum is an intermediate oil obtained by extracting a lubricating oil fraction oi petroleum with phenol at about F. and reextracting the phenolextract with furi'ural at about 150 F. to obtain said intermediate oil as a railinate.

' JOHN P. BUC' BENCES GITED UNITED STATES PATENTS Number Name Date 2,378,820 Amott a July 19, 1945 2,379,312 May June 26, 1946 2,392,252 May Jan. 1, 1946 2,392,253 May Jan. 1, 1946 2,417,415 Hughes 1a, 194'!