USRE22829E - Compounded hydrocarbon oil - Google Patents

Description

Reissued Jan. 14, 1947 COMPOUNDED HYDROCARBON OIL' John T. Rutherford and Robert J. Miller, Berkeley, Calii., assignors, by mesne assignments, to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Original No. 2,252,984, dated August 19, 1941, Serial No. 272,154, May 6, 1939. Application for reissue June 14, 1945, Serial No.

This invention relates to a new and useful composition of matter and involves a composition comprising a hydrocarbon, suchas a viscous hydrocarbon oil, and a polyvalent metal salt of sulfur containing substituted acids of phosphorus.

The production of improved hydrocarbon oils and particularlyof lubricating oils having desired 7 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 agent cannot be predicted.

A characteristic which has been the subject of extensive investigation is the tendency of hydrocarbon oiis 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 oilto 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 engine without the necessity of major overhauls heretofore occasioned by stuck piston rings.

It should be noted that stabilizing agents which are efiective at low temperatures to impart increased stability to hydrocarbon oils, or which -19 Claims. (Cl. 252-32.?)

are efiective at temperatures even as high as 200 or 250 F., are often ineffective under the more severe operating conditions and higher temperature level to which lubricating oils are subjected in Diesel engines. Thus the operatlveness of a. stabilizer at atmospheric temperatures, or even temperatures as high a's 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.

The present invention involves the discovery that dispersion of high molecular weight'polyvalent metal salts of sulfur containing substituted acids of phosphorus in hydrocarbon oils, such as mineral lubricating oil, imparts new, unpredictable and highly desirable properties to the composition. These new properties render the compounded oil particularly useful for various purposes. Although increased resistance to deterioration 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, that different compounds of the general type herein involved vary in their degree of effectiveness and may impart one or more other desirable properties to the lubricating composition. 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.

It has also been discovered that certain metal salts of sulfur containin substituted phosphoric acids have a combination of properties heretofore unknown and particularly desirable in compounded mineral oils, 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, low corrosivity a respects the chemical action of the compounded oil on hearing metals, such as cadmium-silver and copper-lead alloys, as well as the power to inhibit the corrosive action of highly paraflinic oils on these bearing metals. .Although various compounded mineral oils are known which are capable of inhibiting piston rin sticking, the discovery of specific compounding agents capable of imparting the above combination of properties to hydrocarbon oils represents an unobvious and important contribution.

Salts of sulfur-containing substituted acids of phosphorus which may be added to hydrocarbon lubricating oils to provide a new composition of v matter of the type herein involved comprise com- Ma (RXlbHcPYd) e where M is a metal selected from groups II, III. IV and VI of Mendeleeffs Periodic Table of the Elements. Specific examples of such metals are calcium, barium, strontium, aluminum, chromium, lead and magnesium. Within the broader aspects of the invention M may also be selected from the group iron, cobalt, nickel, zinc and tin. In the above formula, B. may be a high molecular weight alkyl, aryl, alkaryl, aralkyl or cyclic non-benzenoid 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 may be zero or a small whole number.

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

monotbloester of phosphoric acid;

dl-thio ester of phosphoric acid;

mono-ester of tetra-tbiopliosplioric acid; I

dl-estcr of t'etra-thiophosplioric acid;

monothioester oi tetrathiophosphorlc acid;

di-thloester oi tetra-tbiophosphoric acid;

' 4 o a S=P -0H mono-ester of mono-thiophosphoric acid;

0 B. S =P O R Iii-ester of mono-thiosphosphoric acid;

substituted acids of phosphorus containing high 7 molecular weight organic radicals. Additional examples of such acids which may be used in forming the metal salts of the present invention are as follows:

mono-thioester of phosphonic acid;

In all of the above formulae R and R are high molecular weight alkyl, aryl, alkaryl, aralkyl or cyclic non-benzenoid groups.

In general, polyvalent metal salts of sulfur containing substituted derivatives of acids of phosphorus such as phosphorus acid, H3PO3; hypophosphoric acid, H2PO3; orthophosphoric acid, H3PO4; pyrophosphoric acid, H4P2O7; monothiophosphoric acid, HsPSOa; di-thiophosphoric acid, H3PS2O2; trithiophosphoric acid, H3PS3O; tetra-thiophosphoric acid, Hal-S4; thiopyrophos phoric acid, H4P2S1; and'trithiopyrophosphoric acid, H4P2S3O4 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 eitherdirectly attached to the phosphorus mono-estcr oi trithiophosphonic acid;

mono-thioestcr of trithiophosphonic acid.

' --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 nesium tetra-chloro-octadecyl magnesium di-(G-chloro, 2-phenyl phenyl) thio-' cresyl phosphate, although less eflective than the prevlously'recited compounds, improve various properties of the oil, particularly its resistance num tetra chloro octadecyl thiophos'phate.

aluminum di-(G-chloro, 2-phenyl phenyl) thiophosphate, aluminum di-(3-methyl, 4-chlorophenyl) thiophosphate, 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-chlorooctadecyl thiophosphate, calcium di-(G-chloro, 2-phenyl phenyl) thiopho'sphate, calcium di-(3- methyl, 4-chloro-phenyl) thiophosphate, barium lauryl thiophosphate, barium octadecyl thiophosphate, barium spermol thiophosphate, barium oleyl thiophosphate, barium spermenyl thiophosphate, barium di-(amyl phenyl) thiophosphate, barium naphthenyl thiophosphate, barium dicyclohexanyl thiophosphate, barium tetrachloro-octadecyl thiophosphate, barium di- (6- chloro, 2-pheny1 phenyl) thiophosphate, barium di-(3-methyl, 4-chloro-phenyl) thiophosphate, chromium lauryl thiophosphate, chromium octadecyl thiophosphate, chromium spermol thiophosphate, chromium oleyl thiophosphate, chromium spermenyl thiophosphate, chromium di-(amyl phenyl) thiophosphate, chromium naphthenyl thiophosphate, chromium di-cyclohexanyl thiophosphate, chromium tetra-chlorooctadecyl thiophosphate, chromium di-(G-chloro, 2-phenyl phenyl) thiophosphate, chromium di- (3-methyl, 4-chloro-phenyl) thiophosphate, lead lauryl thiophosphate, lead octadecyl thiophosphate, lead spermol thiophosphate, lead oleyl thiophosphate, lead spermenyl thiophosphate, lead 'di-(amyl phenyl) thiophosphate, lead naphthenyl thiophosphate, lead di-cyclohexanyl thiophosphate, lead tetra-chloro-octadecyl thiophosphate, lead di-(6-chloro-2-phenyl phenyl) thiophosphate, lead di-(3-methyl, 4-chloro-phenyl) thiophosphate, magnesium lauryl thiophosphate,

, magnesium octadecyl thiophosphate, magnesium spermol thiophosphate, magnesium oleyl thicphosphate, magnesium spermenyl thiophosphate, magnesium di-(amyl phenyl) thiophosphate, magnesium naphthenyl thiophosphate, magnesium di-cyclohexanyl thiophosphate, magthiophosphate,

phosphate, magnesium di-(B-methyl, 4-chlorophenyl) thiophosphate. 3

It should also be understood that thesulfur containing substituted acids of phosphorus utilized for preparing the metal salts of this invention may contain organic substituents other than pure hydrocarbon groups. The organic radical in the acid of phosphorus may comprise, in addition to carbon and hydrogen, substituents such as the halogens chlorine or bromine, hydroxy, sulfhydryl andsimilar groups. Likewise,

the sulfur in the sulfur containing atom need not necessarily be directly attached to the phosphorus atom.

An acid which illustrates these types of 6 compounds comprises the phosphoric acid ester or di-(p-hydroxy phenyl) sulfide.

The acids 01' phosphorus utilized in the present composition may be prepared by various methods. For example, a mixture of a higher alcohol and phosphorus pentasulfide, a mercaptan and phosphorus pentoxide, a mercaptan and phosphorus pentasulfide or a three-component mixture such as a mercaptan, phosphorus pentoxide and pyrophosphoric 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 equaonsz 2RSH+PzOs- H2RSPO:+RSPO: 2RSH+RSPOz+HPzO7- 3HzRSPOa For example, thio-cresyl phosphoric acid may be prepared by reacting thio-cresol with phosphorus pentoxide and pyrophosphoric acid at a temperature not in excess of 250 F. The thio-cresol 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 heavy metal or alkaline earth metal salt precipitated therefrom. For instance, the calcium salt may be manuiactured by precipitation as follows: Water and caustic potash are charged to a mixer and heated to a temperature of 180 F. The acid is added, thereby forming an alkali salt. An aqueous calcium chloride solution is incorporated with violent agitation during precipitation to prevent inclusion of the potassium salt. The precipitated curd is washed free of inorganic salts with hot fresh water. Mineral oil is then added and the solution is dehydrated as by heating to a temperature Of 300-330 F, The concentrated oil solution so obtained may conveniently be used for mixing or blending with other oils to prepare the completed product.

Either normal or basic aluminum salts may be prepared by the precipitation method. The normal salts will contain three equivalents of the acid per atom of aluminum, whereas the basic saltshould contain less than three equivalents of the substituted acid of phosphorus.

Calcium salts may also be prepared in a nonaqueous environment as by the reaction of calcium carbide with the free substituted acid to give acetylene and the anhydrous calcium salt. Aluminum salts may likewise be prepared in an environment substantially free of water by the reaction of aluminum chloride with the free substituted acid of phosphorus. Such aluminum salts have properties different from the salts prepared by precipitation in aqueous solutions. Although these latter salts are useful, aluminum salts prepared by precipitation from aqueous solutions are preferred where the ability to inhibit piston ring sticking in lubricating oils is the property desired.

By way of illustration and to demonstrate the unusual properties possessed by the compounded oils of this invention, test data are given in Table 1.

Table I gxldntor Hours at: e. c. Compound Method of manufacture of acid cent oxygen ab- Suck aorbcd ln 2 5 piston rings hours COMPOUNDED IN ACID REFINED WESTERN OIL B. A. E. 30

Mineral oil o 324 Calcium phosphate of p-hydroxydiphenyl sulfide" p-ll'iydroxydiphenylsulilde and P:O +phospho 1 76 eum. Calcium thiocresyl hosgh Thiocresol and Pioi-i-phospholeum 1 50 Calcium cetylthiop osp ate." Cetyl alcohol+P:S 1 48 Do -.do .05 l8 Chromium oetylthlo bospbato .110 1 108 (1.6 hr.) Load cetylthiophosp ate. dn 1 110 Do -do .05 148 Calcium oetylphenylthlophnsphcte..... CetylphenoH-PgS... 1 170 Calcium thiocresylthiophosphate ThiocresoH-Psss- 1 COMPOUNDED IN PENNSYLVANIA OIL S. A. 13.30

Mineral oil "1 Calcium oetylphenylthiophosphate... Cetyalpheuol-i-Prsa o Calgiumtcetylphenyltbiophosphate+ca1cium cetyl- -do cna e. Oglcium thiocresylthiophosphate Thiocresol+Pa l 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 F., which represents very sever 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 fifteenhour intervals for inspection. The jacket temperature was maintained at approximately 375 F. and the sump oil temperature at approximately 220 F. during the test.

In the table above and elsewhere hereinabove, reference is made to a mode of preparing lubricant additives of this invention, wherein an alcohol'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. action of an alcohol or phenol with phosphorus pentasulfide 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 of thiophosphorlc acid but, by the great weight of authority, the'said .esteris believed to have the structure It is known that the re- P255 and cetyl alcohol) and the calcium cetylphenylthiophosphate (Ca salt of acid ester of P285 and cetylphenol) of Table I are calcium,

1 chromium and lead dicetyl dithiophosphates and calcium dicetylphenyl dithiophosphate, respectively.

The compounding agents herein disclosed may 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 cadium-silver bearings may be highly useful and extremely advantageous in-conjunction with the operation of internal combustion engines having hearings or 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 num berv 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 sulfur containing substituted acids of pentavalent phosphorus containing a high molecular weight a'lkyl 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 and the term polyvalent metal" is adopted to distinguish from the alkali metals.

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 eiilciently in such a base oil than in a highly parafllnic oil stock or a highly refined Western oil. However, it is to be understood that the in vention is not limited to any particular base stock since various of the present compounds are more 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 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 oi the substituted acids 01 phosphorus, thickening agents and/or metal soaps in proportions or in amounts insufiicient to form greases, as in the case of mineral castor machine oils or other compounded liquid lubricants.

The compounds or this invention may be added to oils other than hydrocarbon lubricating oils, for example, fuel oils or non-drying vegetable or animal oils.

While the character 01 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 hereby. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples may be eflected in the practice of the invention which is o! the scope of the claims appended hereto.

We claim:

1. A hydrocarbon oil composition comprising a major proportion of hydrocarbon oil or lubricating viscosity and a small amount, suilicient substantially to stabilize the oil against deterioration by heat and oxidation, oi a polyvalent metal salt of a sulfur-containing acid 01 phosphorus. said acid of phosphorus containing at least one oil-solubilizing organic substituent, the number or carbon atoms contained in said acid oi phosphorus being .at least 24.

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

3. The composition claim 1, wherein said acid of phosphorus is a thiophospioric 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 a polyvalent metal salt of an acid ester produced by a reaction of the type:

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 of a polyvalent metal salt of an acid ester produced by a reaction 01' 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. 7

6. The lubricant of claim 4, wherein the polyvalent metal is chromium.

7. The lubricant of claim 4, wherein the polyvalent metal is aluminum.

8. The lubricant of claim 4, wherein the polyvalent metal is lead.

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

' 10. The lubricant of claim 4, wherein said hydroxy compound is a phenol.

11. The lubricant of claim 5, wherein said bydroxy 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 oi. liquid petroleum lubricant and about one quarter to two per cent by weight of a polyvalent metal salt or an acid I ester produced by a reaction 01' the type:

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

14. The lubricant or claim 13, wherein said hydroxy compound is an alcohol.

15. The lubricant of claim 13, wherein said bydroxy compound is a phenol.

16. The lubricant 0! 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 by droxy compound is cetylphenol.

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

wherein ROI-I 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.