USRE22830E - Compounded oil - Google Patents

Description

in Diesel engines.

Reissued Jan. 14, 1947 COMPOUNDED OIL John T. Rutherford and Robert J. Miller, Berkeley, Calif., assignors, by mesnc assignments, to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Original No. 2,252,985, dated August 19, 1941, Serial No. 272,155, May 6, 1939. Application for reissue June 14, 1945, Serial No.

19 Claims.

This invention relates to a new and useful composition of matter and involves a composition comprising a hydrocarbon, such as a viscous hydrocarbon oil, and an alkaline earth metal salt of sulfur-containing substituted acids of phosphorus.

The production of improved hydrocarbon oils, and particularly of lubricating oils having desired characteristics, has been the subject of extensive research and investigation in recent years. Generally speaking, the compounding of hydrocarbon oils to obtain desired characteristics involves empirical phenomena and the action of untested types of compounding agents cannot be predicted.

A characteristic which has been the subject of extensive investigation is the tendency of hydrocarbon oils to deteriorate or partially decompose and oxidize when subjected to high temperatures. This deterioration is evidenced by the deposition of adhesive deposite on hot metal surfaces over which the hydrocarbon oil may flow. It is important that resistance .to such deterioration be imparted to hydrocarbon oils, particularly to lubricating oils, in order that such compositions may be relatively free from the tendency to form such deposits even under high temperatures and severe operating conditions. A direct result of this type of deterioration during lubrication of internal combustion engines, such as engines of the Diesel type, is the tendency of the stabilizer at atmospheric temperatures, or even temperatures as high as 200 to 300 F., gives no adequate basis for predicting the action of the same stabilizing agent at materially higher temperatures and under more severe operating conditions. The disclosures in the prior art relative to such stabilizers therefore cannot serve as a. guide for one seeking stabilizing agents or oxidation inhibitors effective at higher temperature levels. The phenomena involved are catalytic in nature, are highly empirical, and require extensive experimentation to determine the action of a given type of addition agent.

oil to cause or permit the sticking of piston rings.

The crankcase lubricant in internal combustion engines is subjected to extremely severe operating conditions and in engines of the Diesel type the lubricant encounters in the piston ring zone temperatures of from approximately 425 to 650 F. and pressures from the oxidizing combustion gases as high as 750 to 1150 lbs. per sq. in. Addition agents which render hydrocarbon oils resistant to deterioration by heat at high temperature levels in the order of those above mentioned usually impart to the oil the ability to inhibit piston ring sticking in internal combustion engines and permit longer periods of operation of such engines without the necessity of major overhauls heretofore occasioned by stuck piston rings.

It should be noted that stabilizing agents which are effective at low temperatures to impart increased stability to hydrocarbon oils, or which are effective at temperatures even as high as 200 or 250 F., are often ineffective under the more severe operating conditions and higher temperature levels to which lubricating oils are subjected Thus the operativeness of a The present invention involves the discovery that dispersion of high molecular weight alkaline earth metal salts of sulfur-containing substituted acids of phosphorus in hydrocarbon oils, such as mineral lubricating oil, imparts new, unpredictable and h ghly desirable properties to the composition. These new properties render the compounded oil particularly useful for various purposes. rioration at high temperature levels comprises one of the principal advantages of the compounded oil of this invention, it is to be understood that the invention is not limited to this feature and that different compounds of the general type involved herein vary in their degree of eifectiveness. In general, however, it has been discovered that the new compositions herein disclosed are more stable to heat than is a hydrocarbon oil with which the compositions are compounded. The new compositions of this invention are therefore useful where resistance to deterioration by heat is important. An example of such utility other than as a lubricating oil comprises use as a heat transfer fluid where it may be desirable to inhibit or prevent the formation of a deposit on the metal surfaces from or to which heat is being conveyed. Likewise. the increased resistance to oxidation imparted to the oil by the compounds of this invention will find various applications as, for instance, in insulating, switch or transformer oils.

Although increased resistance to detehibiti g piston ring sticking, the discovery of Elements. Examples of such metals are calcium,

cacao respects the chemical action of the compounded oil on hearing metals, such as cadmium-silver and copper-lead alloys, but the capacity to actually inhibit the corrosive action of highly paraflinic oils on these bearing metals, and the capacity to inhibit piston ring sticking and ring slot carbon formation in paramnic lubricating oils of,the Pennsylvania type. Although various compounding agents are known which are capable of inspecific agents capable of imparting the above combination of properties to hydrocarbon oils represents an unobvious and important contribution.

Alkaline earth metal salts of sulfur-containing substituted acids of phosphorus which may be added to hydrocarbon lubricating oils to provide a new composition of matter of the type herein involved comprise compounds which may be represented by the general formula:

Ma( (RX) bHcPYd) c Q where M is an alkaline earth metal selected from roup II of Mendeleeifs Periodic Table of the strontium and barium. For the purposes of'this invention, in its broader aspects, magnesium may also be classified as an alkaline earth metal. In the above formula R may bea high molecular weight alkyl, aryl, alkaryl, aralkyl, or cyclic nonbenzenoid groups; X and Y each are either sulfur or oxygen and sulfur; H is hydrogen; P is phosphorus; a, b, d and e represent small whole numbers, and 0 may be zero or a small whole number.

The salts of this invention are preferably formed from substituted acids of pentavalent 1 phosphorus of one or more'of the following type mono-ester of mono-thiophosphoric acid di-ester oi mono-thiophosphoric acid where R and R are high molecular weight alkyl,

aryl, alkaryl, aralkyl, or cyclic non-benzenoid groups. Thus R and B. may be any of the following groups: cetyl, cetylphenyl, lauryl, octadecyl, spermol, oleyl, spermenyl, amylphenyl,

tetra-chloro-octadecyl and 6-chloro, 2-phenyl phenyl. Examples of preferred type acids are high molecular weight aIkyl or alkaryl sulfurcontaining substituted phosphoric acids. Howan O=PR' OR s=r1v sa s p a mono-thioester of phosphonic acid monoester of trithiophosphonic acid mono-thioester of trithiophosphonic acid.

In all of the above formulae R and It may be' alkyl, aryl, alkaryl, aralkyl, or cyclic non-benzenoid groups.

In general, alkaline earth metal salts of sul-. fur-containing substituted derivatives of acids of phosphorus, such as phosphorous acid, HsPOa; hypophosphoric acid, HzPOz; orthophosphoric acid HzPOt; pyrophosphoric acid, 114F201; monothiophosphoric acid, HsPSOs; dithiophosphoric acid, HaPSzOz; trithiophosphoric acid, HaPSaO; tetra-thiophospho'ric acid, H3PS4; thiopyrophosphoric acid, I-hPaS-i; and trithiopyrophosphoric acid, H4P2Sa04, fall within the broadest aspects of the invention. By "substituted acids" or substituted derivatives" of phosphorus, whenever used herein, it is intended to designate acids of phosphorus containing an organic group of the type previously listed. The organic group may be either directly attached to the phosphorus atom of the compound or attached thereto through an intervening atom such as oxygen or sulfur. The term sulfur-containing" is intended to designate compounds in which either the original acid of phosphorus or the organic derivative thereof contains sulfur.

The preferred acids are sulfur-containing substituted acids of pentavalent phosphorus and the preferred salts comprise calcium salts of such acids. Examples of preferred salts are calcium cetyl thiophosphate, calcium cetyl phenyl thiophosphate, and a calcium salt of the acid phosphoric acid ester of dl-(p-hydroxy phenyl) sultide. Salts such as calcium thiocresyl phosphate a re less eil'ective than the previously recited compounds but improve various properties of the oil, particularly its resistance to oxidation.

Additional examples of salts within the scope of the invention are calcium lauryl thiophosphate, calcium octadecyl thiophosphate, calcium spermol thiophosphate, calcium oleyl thiophosphate, calcium spermenyl thiophosphate, calcium di-(amyl phenyl) thiophosphate, calcium naphthenyl thiophosphate. calcium di-cyclohexanyl thiophosphate, calcium tetra-chloro-octadecyl thiophosphate, calcium di-(fi-chloro, 2-phenyl phenyl) thiophosphate, calcium di-(3-methyl, 4-chloro- 7o pheryl) thiophosphate, barium lauryl thiophosphate, barium octadecyl thiophosphate, barium spermol thiophosphate, barium oleyl thiophosphate, barium spermenyl thiophosphate, barium di-(amyl phenyl) thiophosphate, barium naph- 76 thenyl thiophosphate, barium di-cyclohexanyl thlophosphate, barium tetra-chloro-octadecyl thiophosphate, barium di-(fi-chloro, Z-phenyl 'phenyl) thiophosphate, and barium di-(B-methyl, 4-chlcro-phenyl) thiophosphate.

6. stance, the calcium salt may be manufactured by precipitation as follows: Waterand caustic potash are charged to a mixer and heated to a temperature of 180 F. The acid is added, thereby The sulfur-containing substituted acids of 5 forming an alkali salt. An aqueous calcium phosphorus utilized for preparing the alkaline chloride solution is incorporated with violent agiearth salts of this invention may contain organic tation during precipitation to prevent inclusion substituent-s other than pure hydrocarbon groups. of the potassium salt. The precipitated curd is The a c radical in the acid of phosphorus washed free of inorganic salts with hot fresh y O Drise, in addition to the carbon and hywater. Mineral oil is then added'and the soludrogen, substi-tuents such as the halogens, chlotion is dehydrated as by heating to a temperaline bromine. Y Y, sulfhydryl and similar ture of BOO-330 F. The concentrated oil solution groups. Likewise, the sulfur in the sulfur-conso obtained may conveniently be used, for mixing taining atom need not necessarily be directly r blending t other 11 t prepare t attached to the phosphorus atom. An acid which 15 leted product. illustrates these types of compounds p s s The alkaline earth salts may also be prepared the p p ric acid ester of di-(p-hydroxy in the non-aqueous environment by the reaction P y s fi of a metal carbide with the free substituted acid.

The acids of phosphorus utilized in the present For example, calcium carbide may be reactedwith composition may be prepared by various methods. free cetyl thiophosphoric acid to yield acetylene For example, a mixture of a higher alcohol and and anhydrous calcium cetyl thiophosphate. phosphorus pentasulfide, a mercaptan and phos- By way of illustration and to demonstrate the phorus pentoxide, a mercaptan and phosphorus unusual properties possessed by the compounded pentasulilde or a three-component mixture, such oils of this invention, test data are given in Taas a mercaptan, phosphorus pentoxide and P oble 1:

Table I Oxidator test: cc. Hours to Compound Method of manuiacturc or acid g 5% ggfigg s g g as we COMPOUNDED IN ACID REFINED WESTERN OIL S. A. E.

Mineral oil 0 324 Calcium phosphate of p-hydroxydip-Hydroxydiphenylsullide and 1 76 phenylsu flde. PgOH-phospholeum. Calcium thiocresylohosphate. Thiocresol and POs+phospholeum l Calcgim cctylthiophosphate- Cctyil alcobol+P=S| 0% o o Calcium cetylphenvlthiophosphata- Cetyl phenol-HHS; l Culclum thiocresylthiophosphate ThiOOl'BSDH-PzS; l

COMPOUNDED IN PENNSYLVANIA OIL S. A. E. 30

o Calcium cetylphenyltbiophosphate+ calcium eetyiphenate. Calcium thiocresylthiophosph ate.

Thiocresol+PzS phosphoric acid, may be directly fused in proportions to give acid esters. The reaction by which the substituted phosphoric acid is formed in the last mentioned three-component mixture is believed to be represented by the following equations:

2RSH+P2O5 H2RSPO3+RSPO2 2RSH+RSPO2+H4PzO7- 3H2RSPO3 For example, thio-cresyl phosphoric acid may be prepared by reacting thiocresol with phosphorus pentoxide and pyrophosporic acid at a temperature not in excess of 250 F. The thiocresol is charged to a stainless steel mixer equipped with a jacket. Steam is admitted in the jacket until a temperature of 200 F. is reached, at which temperature the phosphorus pentoxide and pyrophosphoric acid are added. Water is circulated through the jacket at this time to control the reaction temperature. Stirring is continued until the reaction is complete and the product withdrawn.

In preparing the metal salts involved herein the alkali metal salt of the above acid may be dissolved in aqueous solution and the alkaline earth metal salt precipitated therefrom. For in- It will be observed that all of the compounding agents were effective to very substantially inhibit the absorption of oxygen in, and deterioration of the mineral lubricating oil in the oxidator test. This test is described by Dornte in the Journal of Industrial and Engineering Chemistry, 1936, vol. 28, page 26, and was carried out in the present examples at 340 R, which represents very severe conditions.

In the piston ring sticking tests a single cylinder, 2% bore, 2 /2" stroke, Lauson gasoline engine was operated under extremely severe conditions for the purpose of developing fully piston ring sticking and piston gumming tendencies under circumstances simulating severe operating conditions encountered in the field. Operation of the motor during test was continuous at 1600 R. P. M. except for periodic shut-downs at fifteen-hour intervals for inspection. The jacket temperature was maintained at approximately 375 F. and the sump oil temperature at approximately 220 F. during the test.

reference is made cant additives of this invention,

hol or a phenol is reacted with phosphorus pentasulfide to produce a sulfur-containing acid of phosphorus. Salts of these acids are formed to be used as lubricant additives. It is known that the reaction of an alcohol or phenol with phosphorus pentasulflde proceeds in this manner:

wherein ROH is an alcohol or a phenol. There is some uncertainty as to the exact structure of the resulting ester 01 thiophosp'horlc acid but, by the great weight of authority, the said ester is believed to have the structure rs-n In any event, it is certain that when an alcohol I or a phenol is reacted with P285 to give an acid ester, the product is predominantly a di-ester (i. e., containing two alcoholic or phenolic radicals) containing two sulfur atoms in the molecule. See, for example, Pishchimuka, J. Chem. Ukraine, vol. 1, p. 8'! (Chem. Abstracts, vol. 20, p. 2816, (1926)), and J. Russian Physical Chemical Society, vol. 44, 1406 (C. A., vol. .7, 987 (1913)) and vol. 56, p. 11 (C. A., vol. 19, 2808 (1925)) Wagner- Jauregg et al., Berichte d. deut. Chem. Ges., vol. 7413, p. 1513 (1941); and United States Patents Nos. 1,748,619 (Romieux and Wohnsiedler), 1,889,943 (Barsky and Heuser), 1,893,018 (Christmann) .and 2,063,629 (Salzberg and Werntz).

Thus the calcium, chromium and lead cetylthiophosphates (Ca, Cr and Pb salts of acid ester of PzSs and cetyl alcohol) and the calcium cetylphenylthiophosphate (Ca salt of acid ester oi P255 and cetylphenol) of Table I are calcium, chromium and lead dicetyl dithiophosphates and calcium dicetylphenyl dithiophosphate, respectively.

The compounding agents of this invention are outstanding in that they are more effective to inhibit piston ring sticking in Pennsylvania type oils than are any compounds heretofore found. As has been pointed out hereinbefore, the compounding agents are also eflective to inhibit the corrosive action of parafllnic oils on bearing metals, such as copper-lead or cadmium-silver alloys. Corrosion data, together with data on the increase in viscosity of the oil and A. S. T. M. insolubles, are given in Table II:

The above corrosion tests were carried out in the following manner: Glass tubes 2 inches in diameter and 20 inches long were immersed in an oil bath. the temperature or which was automatically controlled to within :1" F. oi the test temperature, which was 300 F. Approximately 300 c. c. 01 oil under the test was placed in each tube and air was bubbled through it at the rate of liters per hour. Strips o! the difierent types of bearing metals were cut to size and placed in have one or more advantages, depending upon the particular compound selected, the proportion utilized, and the environment which the lubricating oil is to encounter. It should be observed, for example, that even though a compounded oil may be somewhat corrosive to copper-lead or cadmium-silver bearing metals, Babbitt bearings are little, if at all, affected by such corrosive action. Hence, compounded oils which may not be particularly desirable for lubrication of copper-lead or cadmium-silver bearings may be highly useful and extremely advantageous in conjunction with the operation of internal combustion engines having bearings of Babbitt or other corrosion-resistant bearing metals. The present invention in its broader aspects is therefore not limited to a particular compound having all or the greatest number of advantages, but embraces various of the less advantageous addition agents which will find utility inpartioular appl'cations where all the possible improvement in properties may not be required or where the standard of performance may not be so high.

Present experience indicates that where the properties desired involve the ability to stabilize lubricating oils under severe operating conditions, such as those encountered in'the lubrication of pistons and piston rings of lntemal combustion engines of the Diesel type. alkaline earth salts of sulfur-containing substituted acids of pentavalent phosphorus containing a hi h molecular weight alkyl or alkaryl substituent should be utilized.

A moderately acid refined Western naphthenic The proportion 01' the alkaline earth metal salts of substituted acids of phosphorus added to mineral lubricating oils may vary widely depending on the uses involved and the properties desired. As little as 0.05% by weight of the compound gives measurable improvements, particularly as respects inhibiting oxidation and color stability of the compounded oil. From approximately 0.25 to approximately 2% or the compound may be added to lubricants where increased stability in lntemal combustion engines and resistance to piston ring sticking comprise the principal properties desired. Solutions containing more than 2% of the compounds in mineral oil may be utilized for the purpose of preparing lubricating greases and concentrates capable of dilution with lubricating oils and the like. Such higher concentrations comprise a convenient method of handling the compounds and may be used as addition agents for lubricants in general as well as for other purposes.

The alkaline earth metal salts of this invention may be added to hydrocarbon oils containing other compounding ingredients such as pour point depressors, oiliness agents, extreme pressure addition agents, blooming agents, compounds for enhancing the viscosity index of the hydrocarbon oil, corrosion inhibitors and the like. The invention in its broader aspects embraces mineral hydrocarbon oils containing, in addition to metal salts of the substituted acids of phosphorus, thickening agents and/or metal soaps in proportions or in amounts insuii'icient to form reases, as in the case of mineral castor machine oils or other compounded liquid lubricants.

The compounds of this invention may be added to oils other than hydrocarbon lubricating oils, for example, fuel oils, non-drying vegetable or animal oils, or synthetic oils, such as olefin polymers and hydrogenated olefin polymers.

While the character of the invention has been described in detail and numerous examples of the composition given, this has been done by way of illustration only and with the intention that no limitation should be imposed on the invention thereby. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples may be effected in the practice of the invention which is of the scope of the claims appended hereto.

We claim:

1. A hydrocarbon oil composition comprising a major proportion of hydrocarbon oil of lubricating viscosity and a small amount, sufficient substantially to stabilize the oil against deterioration by heat and oxidation, or an alkaline earth metal salt of a sulfur-containing acid of phosphorus, said acid of phosphorus containing at least one oil-solubilizing organic substituent, the number of carbon atoms contained in said acid of phosphorus being at least 24.

2. The composition or claim 1, wherein said acid of phosphorus is an acid of pentavalent phosphorus.

3. The composition of claim 1, wherein said acid of phosphorus is a thiophosphoric acid and contains two hydrocarbon substituents each containing at least 12 carbon atoms.

4. A liquid petroleum lubricant containing about one quarter to two per cent by weight of an alkaline earth metal salt of an acid ester produced by a reaction oi. the type:

ZROH-i-PaSs-RaPOzSzH-l-HaS wherein ROH is an hydroxy compound selected from the group consisting of alcoholic hydroxy compounds and phenolic hydroxy compounds, said salt having at least 24 carbon atoms per molecule.

5. A liquid petroleum lubricant containing about one quarter to two per cent by weight oi w an alkaline earth metal salt or an acid ester produced by a reaction of the type:

wherein ROH is an hydroxy compound selected from the group consisting of alcohols and alkyl phenols, said salt having at least 24 carbon atoms per molecule.

6. The lubricant of claim 4, wherein the alkaline earth metal is calcium.

7. Th lubricant of claim 4, wherein the alkaline earth metal is barium.

8. The lubricant of claim 4, wherein the alkaline earth metal is magnesium.

9. The lubricant of claim 4, wherein said bydroxy compound is an alcohol.

10. The lubricant of claim 5, wherein said hydroxy compound is a phenol.

11. The lubricant of claim 5, wherein said hydroxy compound is an alcohol.

12. The lubricant of claim 5, wherein said hydroxy compound is an alkyl phenol.

13. A liquid petroleum lubricant composition containing a major portion of liquid petroleum lubricant and about one quarter to two per cent by weight of an alkaline earth metal salt of an acid ester produced by a reaction of the type:

16. The lubricant of claim 13, wherein said hydroxy compound is an alkyl phenol.

17. The lubricant of claim 13, wherein said hydroxy compound is cetyl alcohol.

18. The lubricant of claim 13, wherein said hydroxy compound is cetylphenol.

19. A hydrocarbon oil composition comprising a major proportion of hydrocarbon oil of lubricating viscosity and a small amount, suflicient substantially to stabilize the oil against deterioration by heat and oxidation, 01' an alkaline earth metal salt 01' an acid ester produced by a reaction 5o 01' the type:

wherein ROH is an hydroxy compound containing not less than 12 alkyl carbon atoms and selected from the group consisting of aliphatic alcohols and alkyl substituted phenols, said salt having at least 24 carbon atoms per molecule.

JOHN T. RUTHERFORD. ROBERT J. MILLER.