US2416985A - Compounded mineral oil - Google Patents

Description

Patented Mar. 4, 1947 CGMPOUNDED MEIER/AL 91L Bruce B. Farrington, James 0. Clayton, and John T. Rntherfcrd, Berkeley, Calif., assignors, by mesne assignments, to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Original application November 21,

1938, Serial No. 241,648. Divided and this application January 11, 1941, Serial No. 374,078

4 {)laims.

This invention relates to a new and useful composition of matter and involves a composition comprising a viscous hydrocarbon oil and a polyvalent metal salt of certain 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 deposits 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 oil to cause or permit the sticking of pistonrings.

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 e25 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 tem-, perature levels to which lubricating oils are subjected in Diesel engines. Thus the operativeness of a 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.

Th present invention involves the discovery that dispersion of polyvalent metal salts of substituted oxy acids of phosphorus in hydrocarbon oils such as mineral lubricating oil imparts new, unpredictable and highly desirable properties to the compositinon. These new properties render the compounded oil particularly usefulfor various purposes. Although increased resistance to deterioration at high temperature levels comprises one of th principal advantages of the compounded oils of this invention, it is to be understood that the invention is not limited to this feature, that different compounds of the general type herein involved vary in their degree of eifectiveness and may impart one ,or more other desirable properties to th lubricating composition. For example, certain of the compounds reduce the amount of Wear produced as compared with a straight uncompounded mineral oil. The same or other compounds inhibit the corrosion of copper-lead or cadmium-silver bearing metals, etc. 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 an insulating, switch, or transformer oil.

It has also been discovered that certain metal salts of substituted oxyphosphoric acids have a combination of properties heretofore unknown and particularly desirable in compounded mineral oil, namely, the ability to inhibit oxidation and, impart to lubricating oils increased resistance to deterioration by heat, the ability to inhibit piston ring sticking, freedom from the production of increased wear on cylinder .walls and piston rings as compared with uncompounded mineral oils, and low corrosivity asrespects the chemical action of the compounded oilv onbearing metals such as cadmium-silver and copperlead alloys. Although various compounded mineral oils are known which are capable of inhibiting piston ring sticking, the discovery of sheciflc compounding agents capable of imparting the above combination of properties to hydrocarbon oils represents an unobvious and important contribution.

Metal salts of substituted oxy acids of phosphorus which may be added to hydrocarbon lubricating oils to provide a new composition of matter of the type herein involved comprise the salts of metals selected from groups 11, III, IV and VI of Mendeleffs Periodic Table of the Elements. Specific examples of such metals are aluminum, calcium, barium, strontium, chromium and magnesium. Salts of iron, cobalt, nicke1, zinc, tin and lead comprise additional examples of compounds falling within the broader aspects of the invention.

The metal salts of this invention are preferably formed from substituted oxy acids of pentavalent phosphorus of the following type formulae:

where R and R may be alkyl, aryl, alkaryl, aralkyl or cyclic nonbenzenoid radicals. Substituted phosphoric acids containing at least twelve carbon atoms are preferred. Examples of preferred type acids are alkyl or alkaryl substituted phosphoric acids having at least twelve carbon atoms in the molecule. However, it is to be understood that the broader aspects of the invention include the use of other types of substituted oxy acids of phosphorus containing more than twelve carbon atoms. Additional examples of substituted oxy acids of phosphorus which may be used in forming the metal salts of the present invention are as follows:

Phosphonic acid Monoester of phosphonic acid In all of the above formulae R and R may be alkyl, aryl, alkaryl, aralkyl or cyclic nonbenzenoid groups.

In general, polyvalent metal salts of substituted derivatives of oxy acids of phosphorus such as phosphorous acid, hypophosphoric acid, HzPOs; orthophosphoric acid, H3PO4; pyrophosphoric acid, H4P2O7; fall within the broadest aspects of the invention. By substituted or substituted derivatives of acids of phosphorus whenever used herein, it is intended to designate acids containing an organic group of the type previously listed, 1. e., alkyl, aryl, alkaryl, aralkyl, or cyclic nonbenzenoid groups. The organic groups may be either directly attached to the phosphorus atom of the compound or attached thereto through an intervening atom such as oxygen. The term oxy acids of phosphorus is intended to designate throughout the specification and claims acidsiof phosphorus in which one oxygen atom may intervene between the hydrogen and phosphorus atoms of the ester.

The preferred acids are substituted orthophosphoric acids and the preferred salts comprise the aluminum, calcium, barium and chromium salts of these acids. Examples of such salts are aluminum lauryl phosphate, aluminum cetyl phosphate, aluminum octadecyl phosphate, aluminum spermol phosphate, aluminum oley1 phosphate, aluminum spermenyl phosphate, aluminum cetyl phenyl phosphate, aluminum di-(amylphenyl) phosphate, aluminum naphthenyl phosphate; calcium lauryl phosphate, calcium cetyl phosphate, calcium octadecyl phosphate, calcium spermol phosphate, calcium oleyl phosphate, calcium spermenyl phosphate, calcium cetyl phenyl phosphate, calcium di-(amylphenyl) phosphate, calcium naphthenyl phosphate; chromium lauryl phosphate, chromium cetyl phosphate, chromium octadecyl phosphate, chromium spermol phosphate, chromium oleyl phosphate, chromium spermenyl phosphate, chromium cetyl phenyl phosphate, chromium di-amylphenyl) phosphate, chromium naphthenyl phosphate; barium lauryl phosphate, barium cetyl phosphate, barium octadecyl phosphate, barium spermol phosphate, barium oleyl phosphate, barium' of the invention are: aluminum dicyclohexanyl phosphate, aluminum distearoglyceryl phosphate, aluminum tetrachloro-octadecyl phosphate, aluminum di- (6-chloro, Z-phenyl phenyl) phosphate, aluminum di-(3-methy1, 4-chloropheny1) phosphate; calcium dicyclohexanyl phosphate, calcium distearoglyceryl phosphate, calcium tetrachloro-octadecyl phosphate, calcium di-(G-chloro, Z-phenyl phenyl) phosphate, calcium di-(3- methyl, 4-chlorophenyl) phosphate; chromium dicyclohexanyl phosphate, chromium distearoglyceryl phosphate, chromium tetrachloro-octadecyl phosphate, chromium di-(B-chloro, 2-phenyl phenyl) phosphate, chromium di-(3-methyl, 4- chlorophenyl) phosphate; magnesium dicyclohexanyl phosphate, magnesium distearoglyceryl phosphate, magnesium tetrachloro-octadecyl phosphate, magnesium di-(6-chloro, Z-phenyl phenyl) phosphate, magnesium di-(B-methyl, 4- chlorophenyl) phosphate, magnesium lauryl phosphate, magnesium cetyl phosphate, magnesium octadecyl phosphate, magnesium spermol phosphate, magnesium oleyl phosphate, magnesium spermenyl phosphate, magnesium cetyl phenyl phosphate, magnesium di-(amylphenyl) phosphate, magnesium naphthenyl phosphate; barium dicyclohexanyl phosphate, barium distearoglyceryl phosphate, barium tetrachloro-octadecyl phosphate, barium di-(fi-chloro, Z-phenyl phenyl) phosphate, and barium di-(3-methyl, 4ichlorophenyl) phosphate.

The substituted oxy acids of phosphorus utilized in the present invention may be prepared by methods known in the art. For example, a mixture of a higher alcohol and phosphorus pentoxide in ethyl ether may be refluxed for several hours. The reaction by which the substituted phosphoric acid is formed in this operation is believed to be represented by the following equation:

where R is an alkyl radical. The alkyl ethyl phosphoric acid is soluble in ether, while the ethyl meta phosphate is not and the ether solution of the former may-be separated from the latter by decantation. Table 1 gives a number of TABLE 1 Acid Method of preparation Monocetylphosphoric 9.25 lb. cetyl alcohol and 5.61 lb.

P205 were refluxed with 5 gal. ethyl ether for 24 hr. Cetylphosphoric acid solution decanted.

112 gms. solid sperm alcohols, 60 gms. P and 400 gms. ethyl ether treated as above.

100 gms. octadecanol and 150 cc. benzene treated with 56.8 gms. P0013. to give a free acidic hydrogen.

107 gms. oleyl alcohol and 28.5 gms. P20 were refluxed in ethyl ether for 24 hr.

107 gms. liquid sperm alcohols and 27 gms. P 05 refluxed in ethyl ether for 24 hrs.

150 gms. cyclohexanol and 87 gms. P205 refluxed with 150 gms. ethyl ether for 24 hr.

688 gms. cetyl phenol and 316 gms. 235 refluxed with ethyl ether for Mono-spermol phosphoric.

Mono-octadeoylphosphoric...

Mono'oleylphosphorim Mono-spermenyl p h o s phoric.

Dic yclohexanyl phosphoric- (Cetylphenyl) phosphoric.

r. 100 gms. amyl phenol and 43 gms.

P 05 heated to 185 F. for hr.

Di-(amylphenol) phosphoric.

In preparing the metal salts herein involved, the ethyl group in the ethyl phosphoric acid above mentioned may be hydrolyzed off to form the metal salt of the monoalkylorthophosphoric acid, i. e., the salt of RHQPO. This type of operation is not limited to the alkyl derivatives but includes arylethylphosphoric acid, alkarylethylphosphoric acid, aralkylethylphosphoric acid and ethylphosphoric acids containing a cyclic nonbenzenoid group.

The metal salts of the various substituted oxy acids of phosphorus may be conveniently prepared by reacting the acid with sodium hydrox- Product was hydrolyzed 6. ide or potassium hydroxide and then precipitating the desired metal salt from the solution of the sodium or potassium salt by the addition of the appropriate metal ion. The salt may also be prepared by the direct neutralization of the acid as, for example, with lime where the calcium salt is to be obtained.

Basic aluminum salts prepared by the precipitation method are preferred by reason of their low corrosivity to alloy bearing metals although the so-called normal salts are not precluded. It is also preferred to maintain the amount of coprecipitated alkali metal salt in the heavy metal compounds at a minimum because the alkali metal salts decrease the stability of the oil solution in the presence of water.

The calcium salts may also be prepared in the nonaqueous environment by the reaction of calcium carbide with the free substituted acids of phosphorus.

The aluminum salts may also be prepared in an environment substantially free of water by the reaction of aluminum chloride with the free substituted acids of phosphorus. However, such aluminum salts have properties difierent from the unique properties possessed by the compounded oils of this invention, data from extensive tests are given in Table 2.

TABLE 2 Miscellaneous tests Engine tests, Sm

p corrosion Preparation of compound t Lauson ifk Compound cen mac me,

of 1 wear Ring Viscosity Salt pre- Salt stick- Cleanliness Cn-Pb Cd-Ag increase Acid pared ing 0 F. from O) Acid treatedWestern 011.. 0 1.0 Poor 1.0 1.0 477 1.0 AJulrnitnum lauryl phos- 1.0 5.0 Good 0.1 1.5 546 Comanercial lauryl phosphoric Na salt.

p a e. aci

Do 0.05 0.1 0 195 d0 Do, Aluirninum cetyl phos- 1.6 .0 Verygood. 450 Cetyl a1col1ol+PzO +et Do.

p ate.

Do 0.1 4.0 Good 0.2 0.7 161 do Do. Do 0.8 5:1; ..do 0.6 0.7 146 0.58 -.-.do Ksalt Alililmiililum octadecyl 0.15 5.0 Verygood. 0.1 1.0 Octadccylalcohol+POCla Nasalt .p osp ate. Alulminhum sperniol 1.0 5.0 do Low 4.0 Solidspermalcohols+P,O +ether. Do.

p osp ate.

Do 0.7 5.0 do 1.0 1.0 211 -.do Do. Alufininum oleyl phos- 0.7 4.0 Good..... 0.1 1.0 0leylalcohol+PgO +ether Do.

p ate. Aluminum spermenyl 0.3 2.0 Fair.. 0.1 0.2 Liquid sperm alcohol+P2O Do.

phosphate. ether. Aluminum di-cyclohex- 0.1 5.0 Verygood. Cyclohexanol-l-PzO5|-ether Do.

anyl phosphate. Aluminum dHamyl- 1.0 3.0 Fair 0.5 2.0 131 Amylphenol+P10 Do.

phenyl) phosphate. luminum di-stearoglyc- 0.7 2.0 .do Glyceryldistearate+P2O +ether Do. eryl phosphate. Calciumlauryl phosphate. 1.0 2.0 .do 1.0 5.0 451 Commercial lauryl phosphoric Do.

ac Calcium cetylphosphate. 0.5 51 Excellent. 156 CetylalcohoH-P o -l-ether Do 0.9 Verygood. 0.5 1.0 162 0.38 do Chrhbmium cetyl phos- 0.8 o 0.3 0.2 220 ..do Na salt.

p ate.

Do 1.0 5.0 do 199 do Do. Magnesium lauryl phos- 1.0 2.0 Fair 9.0 49.0 401 Commercial lauryl phosphoric Do.

p ate. aci Alulrlninum lauryl phos- 0.3 1.0 -.do 0.1 0.5 284 Lauryl alcohol-i-PCI: Do.

p ite.

1 Expressed as ratio of time to stick rings of compounded oil to that w ith an uncompounded Western acid refined oil SAE 30.

I Expressed as ratio of compoundedoil corrosion toccrrosidnwith Western-acid-refined oil SAE 30 3 Expressed as ratio of wear of compounded oil to that of Western acid refined oil SA The base oil used for testing the addition agent was in all cases an acid refined Western 011 SALE 30 grade.

The above data show that small amounts of most of the addition agents act as corrosion inhibitors even in acid treated Western oils which are ordinarily considered noncorrosive. Likewise, extremely low wear rates Were obtained with the two compounded oils tested in the Weeks machine. .All of the addition agents improved piston cleanliness and imparted resistance to piston ring sticking in engine tests.

In the above piston ring sticking tests a single cylinder 2% inch bore, 2% inch 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 se- Vere operating conditions encountered in the field. Operation of the motor during tests was continuous at 1600 R. P. M. except for shut-downs at fifteen-hour intervals for inspection. The jacket temperature was maintained at 375 F. and the sump oil temperature at 220 F.

The wear tests were carried out in a Weeks machine comprising a /2 inch steel ball pressed against a 1% inch steel cylinder with a force of 40 Has, the cylinder dipping in the oil to be tested and rotating at 600 R. P. M. The duration of the test was sixteen hours and the wear rate determined by measuring the amount of metal removed from the ball. In the above wear tests the lubricant was maintained at approximately 300 F. as indicated.

The 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 of which was automatically controlled to within i1 F. of the test temperature which was 300 F. Approximately 300 cc. of oil under the test was placed in each tube and air Was bubbled through it at the rate of liters per hour. Strips of the difierent types of bearing metals were cut to size and placed in the oils; in most cases the copper-lead mixture and cadmium-silver bearing alloys were tested simultaneously in the same sample of oil. The weight loss of each strip was recorded. Before weighing, each strip was washed in petroleum ether and carefully wiped with a soft cotton cloth. The duration of the test was 72 hours.

To further illustrate the corrosion inhibiting properties of the compounding agents herein disclosed, the following data obtained in the above type strip corrosion test are given:

The compounding agents herein disclosed mal 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 01' Babbitt or other corrosive-resistant bearing metals. The present invention in its broader aspects is therefore not limited to the use of a particular compound having all or the greatest number of advantages, but embraces various of the less advantageous addition agents which will find utility in particular applications 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 internal combustion engines of the Diesel type, polyvalent metal salts of substituted oxy acids of pentavalent phosphorus containing more than twelve carbon atoms in the molecule and preferably containing an alkyl or alkaryl substituent should be utilized. It is to be understood that by polyvalent metal salts used in the above connection the alkaline earth metals are included.

A moderately acid refined Western naphthenic base oil is the preferred oil stock used as a base for the compounded lubricants involved herein. The compounding ingredients appear to function more efiiciently in such a base oil than in a highly paraflinic oil stock or a highly refined Western oil. However, it is to be understood that the invention is not limited to any particular base stock since advantages herein disclosed may be obtained at least to some degree with various oil stocks, the selection of which will be determined by conditions and service which the compounded lubricant is to encounter.

The proportion of metal salts of substituted oxy acids of phosphorus added to mineral lubricating oils may vary widely depending upon the uses involved and the properties desired. As little as 0.05% by weight of the compound gives measurable improvements, particularly as respects the color of the compounded oil after use in internal combustion engines. From approximately 0.25 to approximately 2% of the compound may be added to lubricants where ability to inhibit piston ring sticking comprises the principal property 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 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, color stabilizers, etc. 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 grease-forming proportions or in amounts insufficient to form greases, as in the case of mineral castor machine oils or other compounded liquid lubricants.

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.

This application is a division of our copending application Serial No. 241,648, filed November 21, 1938.

We claim:

1. A base metal salt of a phosphoric acid ester containing at least one alkylaryl group and a total of 5 to 16 saturated carbon atoms in the alkyl radicals of said alkylaryl groups.

2. A metal salt of a phosphoric acid ester containing at least one alkyl aryl group and a total of 5 to 16 saturated carbon atoms in the alkyl radicals of said alkyl aryl groups, the metal of said metal salt being selected from the group consisting of aluminum, calcium, barium, strontium, and magnesium.

3. A calcium salt of a phosphoric acid ester containing at least one alkyl aryl group and a total of 5 to 16 saturated carbon atoms in the alkyl radicals of said alkyl aryl groups.

4. An aluminum salt of a phosphoric acid ester containing at least one alkyl aryl group and a total of 5 to 16 saturated carbon atoms in the alkyl radicals of said alkyl aryl groups.

BRUCE B. FARRINGTON. JAMES O. CLAYTON. JOHN T. RUTHERFORD.