US2349817A - Polycarboxylic acid salts in lube oil compounding - Google Patents

Description

XR 2e343o817 Patented May 30, 1944 UNITED STATES PATENT OFFICE POLYCARBOXYLIC ACID SALTS IN LUBE OIL COMPOUNDING Bruce B. Farrington, James 0. Clayton, and Don- H. Etzler, Berkeley, Calif., assignors to Standard Oil Company of California, San Francisco, Calif., a corporation of Delaware No Drawing. Application March 8, 1940, Serial No. 322,946

18 Claims.

This invention relates to new and useful compositions of matter and to methods of preparing the same. In particular, it relates to compositions comprising hydrocarbons of the lubricatx0 or keto =0 arbamyl C O (NH Alkyl or aryl thiolcarboxyl. -C 0 SR Alkyl or aryl thionocarboxy 0 SO R Mercapto l SH Alkyl or arylthio SR ing oil class, in major part, in which are dis- 5 oil compounding designed to effect a stability in Solved Suspended minor amounts of Certain one direction often brings about a marked inmetal salts of organic aliphatic carboxylic acids, stability i an th r, either alone or in admixture with other com- It has been found that t it t a l pounding agents of the same or different typebricating oil of small amounts of a metal salt of It has long been the desire of the lubricating a aliphatic carboxylic acid, Carrying Substp Oil compounding art to Obtain an oil, Particularly tuted or unsubstituted carboxylic acid group in of petroleum origin, which alone or with the addition t th salt-forming carboxylic acid additionof relatively small amounts of 'comgroup bringseabeutamimpmved stability pounding agents" would resist deterioration drocarbon oils when the same are subjected to degradation when subjected for long periods of high temperatures and pressures in the pres time to high temperatures and pressures, in the ence of oxygen and metals: such acids correspond presence of metals, air or oxygen, or hydrocarbon general to the type HOOC (CHZ)n COOH 53 'contlbustion g g fi Deterioration of in which n may be zero or a whole number gen e c arac er referre o ere manifests itself erall from 1 o 8 inclusive, althou h com n m diverse effects dependent upon the natur? in wl iich n is greater than 8 are fi illy op a tii g degreetgf refitiement z g g qi a in which there may or may not be alkyl aryl an upon e environmen o w 10 1 1S su jected, but reference may be made to Diesel en- 3?? or fi g fi fi g gine piston ring sticking in which the exposure roufi t ifa f still greater i inprove n ien t of the si of a lubr-lcatmg on to Such tempgga'tures as 42-52 sired sort is brought about when in the metal 650 F., in the presence of oxidizing combustion 1 gases at pressures as high as 750-1150 lbs/sq. in., ts of actds the type HOOC (CH2) "T causes the deposition of oil degradation prod- (n=0 8) than 2, P polar nets of such a cementitious character as to elfecgroup Substltutlon 1S effected Positlon alpha, tivew take piston rings out of ervice; to the beta, gamma, delta 01 (Even epsllon t0 the Carbon deposition of sludge" from automobile crank atom of the salt'formmg carboxyhc 301d group, a il apparently as th lt of oxidation the effectiveness for the desired purpose decreasand/or polymerization phenomena; and to the ing in the order of p o as ecited. corrosion of metal bearing surfaces, apparently For the purposes of this invention the term as a result of phenomena which cause the formapolar group iS defi ed a including the followtion of organic acidic products. This situation ing radicals;

Name Formula Name Formula Oarboxylic acid -C O OH Alkamino or arylamino. -NHR Dialkamino or diarylamin Phosphino Name Formula Name Formula Phosphoroso -P O Phosphazo --PN P O 2 Phosphoro.-. PP -O P (O R) 2 Pbosphoarseno PAs -01 (0 RM Arsmo AsH2 or =AsH SiHa Arsenoso... AsO =SlH2 AI'SO -ASO5 SiO 0 R Alkyl or aryl arsenate OAsO (O R) 2 S 0 R Alkyl or aryl srsemte. OAs 0 R) 2 SO3R Alkyl or aryl arsono -AsO (0 R): NHS 0 3R Alkyl or aryl arsinico. AsO 0 R S O QNHQ Arseno. AsAs- -s 0 N n- Stibino- SbH or =sbrr -SeH Stiboso Sb 0 SeR Stibo -Sb 0 z Alkyl or arylant1monate -O SbO (O R) 2 Se 0 Alkyl or aryl stibono Sb 0 (O R) 1 Selenonyl =S80z Alkyl or aryl stibinico. =Sb 0 0 R Alkyl or aryl selenino -Se0 (0 R) Autlmonm -SbSb Alkyl 0r aryl selenono SeO2(O It) Strbarsenm. -SbAs Selenocyano Se C N B lSIIlLlthlllO. BiHz OI =B iH 'iellur TeH Boryl -B 0 Alkyl or aryl tellury TeR Alkyl or aryl borate -OB (O R) 2 T u ='lc Alkyl or aryl silicate. O Si (O R) 2 Alkyl or aryl phosph0n1tc-. P (0 R) 2 Iodoso IO Alkyl or aryl phosphonate PO (0 R) 2 Stannyl S1111; Alkyl or aryl phosphiniteun =P0 R OdOXY I 0 2 Alkyl or aryl phosphinate =PO O R I In the above polar group representations, R represents an alkyl, aryl or aralkylradical. It is to be particularly noted that the simple halogeno groups (-Cl, -Br and I) are not included here,.because of the ease with which these groups split OE and because of the extreme corrosivity and general reactivity of the halogen acids thus formed.

The metals whose substituted carboxylic acid salts are useful for the purposes of the invention may have valences from one to four, inclusive, and the salts offlpotassium, calcium, magnesium, aluminum, chromium, cobalt, lead, manganese, tin and zinc have been found of particular utility.

Among the aliphatic carboxylic acids Whose metal salts are suitable in the practice of the invention and which correspond to the structure HOOC-(CH2) n-COOH (11:0-8 or a higher whole number) there may be mentioned: the oxalic acid series, including oxalic acid itself; malonic acid; isosuccinic or methylmalonic acid and its alkyl homologues such as ethylmalonic, dimethylmalonic, prcpyland iso-propylmalonic, methylethylmalonic, n-butylmalonic, isobutylmalonic, sec-butylmalonic, propylmethylmalonic, isopropylmethylmalonic, diethylmalonic, pentylmalonic, dipropylmalonic and cetylmalonic acids; succinic acid; the mono-alkylic succinic acids such .as methylsuccinic, ethylsuccinic and isopropylsuccinic; the symmetrical dialkylic succinic acids including symmetrical dimethylsuccinic, symmetrical methylethylsuccinic, symmetrical methylisopropylsuccinic, symmetrical diethylsuccinic and analogous higher alkylic homologues; the unsymmetrical dialkylic succinic acids such as unsymmetrical dimethylsuccinic, trimethyland tetramethylsuccinic acids; glutaric acid; a-methylglutaric acid; p-methyland ,e-ethylglutaric acids; the diand tri-alkylic glutaric acids such as a,u-dimethylglutaric, 1- diethylglutaric, a,p-dimethylglutaric, unsymmetrical a,a1-dimethylglutaric, fifi-dimethylglutaric and the higher alkylic homologues of these acids; a,a,a1-trimethylglutaric acid; adipic acid; a methyland a-ethyladipic acids; .B-methyladipic acid; am-diethyland a.a1-dimethyl adipic acids; pimelic acid and the alkylic pimelic acids including 04-, {3-, and v-methylpimelic, n ar-dimethylpimelic and u,[3,a1-trimethylpimelic acids; suberic acid and the alkylic suberic acids; and sebacic and the alkylic sebacic acids. Representative of these aliphatic acids in which one vinylene group is the polar group referred to as augmenting the desired effects in the employment of suitable metal salts, for the purposes of the invention, may be mentioned: the alkylene malonic acids such as methylenemalonic acid, CH2:C(COOH)2; isopropylenemalonic acid and allylmalonic acid, CH2 CH.CH2.CH(COOH) a; fumaric acid; maleic acid; mesaconic acid; citraconic. acid; itaconic acid; glutaconic acid; teraconic acid and hydromuconic acid, together with the alkylic and dialkylic homologues of these oleii ne dicarboxylic acids. As representative of suitable acids in which two vinylene polar groups appear may be mentioned diallylmalonic acid, (CH2ZCH.CH2)2C(COOH)2; muconic acid; and di-isovaleralglutaric acids. Representative of suitable acids in which the ethylene group is the polar group which makes the metal polycarboxylic acid salts especially suitable for the purposes of the invention, may be noted glutinic acid and diacetylenedicarboxylic acid. Examples of suitable acids in which a carboxylic group is the polar radical referred to as desirable are the paraflin tricarboxylic acids such as isobutane-a,a,B-tricarboxylic acid, tricarballylic acid and a,,5trimethyltricarballylic or camphoronic acid, and the alkylic homologues thereof; and the olefine tricarboxylic acids such as aconitic acid and its isomers aceconitic and citracetic acids. Representative of suitable acids in which one or more hydroxy groups are the polar radicals referred to as especially beneficial are tartronic or oxymalonic acid and the several alkylictartronic acids-such as methyltartronic or isomalic acid, ethyltartronic, propyland isopropyltartronic; the -oxyalkylic malonic acids; malic acid and its homologues, for example a-oxypyrotartaric acid, B-methylmalic acid, p-methylethylmalic acid, isopropylmalic acid and the paraconic acids; a-oxyglutaric acid; fi-oxygluta'ric acid; a-hydroxyadipic and a-hydroxysebacic acid; the isomeric tartaric acids; citric acid; and dioxytartaric acid. The polar substituted derivatives of various of these and other aliphatic carboxylic acids, generally partially esterified, in the form of their metal salts, will be referred to below in more detailed exemplification of the practice of the process of the invention. As aforesaid, polar substitution of the character indicated, most suitably in the alpha, beta and gamma positions, and less suitably in the delta, epsilon, etc., positions, relative to the salt-forming carboxyl carbon atom, in the EXAMPLES-SET I Among the beneficial effects which flow from the incorporation of a metal salt or a mixture of metal salts of the above described aliphatic acids in a hydrocarbon oil of the lubricating oil class is the prevention of piston ring sticking, or its marked postponement, under very severe motor conditions, as for example in Diesel engine or in aircraftspark or compression ignition engine operations. r

In the tests Whose results are summarized in Table I, a single cylinder Lauson gasoline sparkignition engine, 2% inch bore and 2 inch stroke, loaded with fan dynamometers, was operated under extremely severe conditions, designed to develop fully the tendency of the crankcase lubricant to deteriorate with gum formation and piston ring sticking: operation was at 1600 R. P. M.; engine jacket temperature was maintained at 375 F.; crankcase oil temperature was maintained at 220 F.; at periods of 15 hours the operations were interrupted and the condition of the piston rings determined. In Table I, the base oil referred to as Western 30" was an acid-refined lube stock of California origin; A. P. I. gravity 21.4"; viscosities at 100 and 210, 622 seconds and 56.6 seconds, respectively, Saybolt Universal. To this base oil were added the various salts in the amounts indicated, by weight. The base or uncompounded oil referred to as Pennsylvania 30 was a solvent refined stock of Pennsylvania origin, A. P. I. gravity 28.6"; viscosities at 100 and 210 F. of 519 and 66 seconds, respectively, Saybolt Universal.

of the cadmium-silver and copper-lead types. This diminution in corrosivity is particularly marked upon the incorporation in the hydrocarbon oils of metal salts of those aliphatic carboxylic acids corresponding to the type HOOC(CH2) nCOOH (n=0-8 or a higher whole number) in which a polar group or radical as above exemplified is substituted for a hydrogen atom attached to a carbon atom in close proximity to the carbon atom of the salt-forming carboxylic acid radical-preferably in the alpha position, less preferably in the beta position and of decreasing desirability and effectiveness in the gamma, delta, epsilon, etc., positions, in the order named.

In the tests whose results are summarized in Tables II, thin sheets of the indicated bearing metals were cut into strips (copper-lead, x 1%" X 6%"; cadmium-silver, A x

1%" x 91;), and these strips were immersed in the exemplified oils carried in 2" x 20" glass test tubes; these test tubes were carried in an oil bath maintained at 300 F.:!:1 F. Each test tube contained approximately 300 cc. of oil, and air was bubbled through each tube at the rat of 10 liters per hour. At the end of each of three 24-hour periods, the strips were removed from the oils, washed with petroleum ether and carefully wiped with a soft cotton cloth; weight losses of the strips were measured in connection with the weight of each individual strip. The duration of the tests was 72 hours, and the weight losses tabulated below are those found at the end of the 72-hour period, except as indicated; the losses reported, however, represent the averages of at least two and sometimes more duplicate or check cor- TABLE I PTeUQTLtlO'IZ or postponement of pzston 1mg sticking Hours to Relative Relative Example 011 cause ring ring slot piston sticking cleanliness cleanliness Western 30 Poor. +0.28% potassium cetyl tartrate G d +0.42% magnesium cetyl tartrate Fair, +0.57% aluminum cetyl tartrate P +0.50% calcium cetyl tartrate Very d,

0 20% calcium cetyl mucate.. Poor.

' Fair.

' Poor.

Fair. Good. Good. Poor. Fair+. o0d- Fair. Poor Poor +0.34% calcium a-eicosenylsuccmate. Fair +0.15% calcium cetyl sebacate.. Poor. +0.40% calcium cetyl a-am1nosuccmate 00+ Very good... Very good. +0.50% calcium cetylpbenate+0.50% calc um ce tyl tartrate Very good... Very good. +0.50% calcium cetylphenate+0.50% calcium d cetyl citrate" 60+ Very good. Very good. +0.50% calcium cetylphenste+0.25% calc um dicetyl citrate"... Very good Very good. +0.50% calcium cetylphenate+0.50% calc um a-e cosyltartrate Very good Very good. +0.50% calcium cetylphenate+0.50% calcium a-eicosenylsuccm- I ate 7 I t l 60 Fair Fair. 0.50 calcium cetylphenate+0.50 0 ca cium ce y a-aminosucv cir 60+ Very good... Very good. g i P 3 4 +0.50 0 ca cium ce y er ra e it +0.50% calcium cetylphenate+0.50% calcium dicetyl 01 at Very good.

N OTE: conclusion of a test of the stated hours duration.

EXAMPLESSET II 1 A plus sign following a stated number of hours in the entepenultimate column indicates free rings at the rosion tests under these conditions. In connection with the results reported in Table II, attention is directed to those oils compounded by the addition of agents other than those of the invention (oils LA, B, C, etc.), in which the compounding, whil perhaps of benefit in respect to some property of the oil, is of definitely deleterious effeet in respect; to the corrosivity of the oil toward bearing metals. Attention is additionally directed to such compounded oils (within the example bracket 32-73) to which have been added, as further compounding agents, the metal salts herein particularly described, wherein it appears that the increased corrosivity due to the original compounding has been prevented or inhibited by the agents of the invention.

TABLE II Reduction of corrosivz'ty to bearing metals cinate +0.507 calcium cetyl iumarate +0.50% calcium cetylphanate+0.50%

Weight loss in mgms., 72 hrs. 'Examplc Oil Cu-Pb CdAg Western 30. 13.9 0.4 1. +0.28% potassium cetyl tartrate 1. 3 0. 1 2 +0.42% magnesium cetyl tartrate--- 2.0 0.3 4 +0.50% calcium cctyl tartrate 1. 3 0.5 5 +0.20% calcium cetyl mucate 1. 6 0. +0.34% potassium cctyl citrate. 8.5 0. 4 7 +0.28% magnesium cetyl citrate 2. 1 0

+0.52% aluminum cetyl citratc 5. 0.5 +0.50% calcium dicetyl citrate 2. 6 1. 4 +0.63% calcium u-eicosyltartrate 5. 0 0. 9 +0.18% calcium cetyl oxalate 1. 2 0 +0.50% calcium cetyl malate 3. 7 0. 1 +0.50% calcium cetyl maleatc 2.0 0 +0.50% calcium a'cetylmalonatc 9. 8 0. 3 +0.50% calcium a-cetenylsuccinate 1. 1 0.3 +0.34% calcium weicosenylsuccmate. 1. 6 0. 1 +0.15% calcium cewl sebacate 7. 1 1. 0 +0.16% calcium cctyl a-ammOSllOClllBtB. 6. 3 0 +0.78% calciumcetyl maloriate 1 3. 4 0.1 +0.50% calcium oetyl a-mercaptosucll. 1 0. 8 l4. 6 l. 5

calcium cetyl tartrate +0.50% calcium cetylphenate+0.50%

calcium dicetyl citrate 9. 1. 3 +0.50% calcium cetylphenate+0.25%

calcium dicetyl citrate 6. 1 0. 1 +0.50% calcium cetylphenate+0.50%

calcium a-eicosenylsuccinate- 40. 7 6.0 +0.50% calcium cetylphenate+0.50%

calcium cetyl a-aminosuccmate- 11. 8 6. 0 +0.50% calcium cetylplienate+0.50%

calcium cetyl wmcrcaptosuccinate" 11. i 0. 8 +0.25% calcium cetylpliosphate+0.50%

calcium dicetyl tartrate 1. 3 0.2 +0.50% calcium stearate 131. 9 180. 5 +1.0% aluminum dinaphthcnate- 67 113 +1.0%magnesium naphthenate. 139 119 +10% calcium cetylphenate 126 12. 1 Pennsylvania 24. 5 l. 6 +0.50% calcium cetyl tarti'ate 1. 3 0.2 +0.50% calcium cetyl citrate-- 18. 7 14.2 +0.50% calcium cetyl a-aminosu 7. l 0- 0 +0.50% calcium cetyl a-mcrcaptosuccinate 2o. 7 2. 2 +0.50% calcium cetylphenat 63. 5 47. 6 +0.75% calcium cetylphenate 166. 6 215. 4 +0.10% calcium ricinoleato 135. 2 222 +0.50% calcium wbromostearate 125. 7 111. 7 +10% aluminum dinaphthenate (24 hrs.) 42. 8 28. 6

EXAMPLES-SET III A still further benefit to be derived from the addition of the metal salts of the invention to hydrocarbon oils, particularly noticeable in the case of salts of those acids carrying polar substituents as described, is a marked lessening of color instability upon exposure of the oils of the invention to heat, in the absence of air or metals.

In the tests Whose results are summarized in Table III, samples of the exemplified oils were held, in glass, at 300 F. for 6 hours. The oils were cooled at the end of this period of time and their colors measured. for comparison with the uncompounded base oil stocks; A. S. T. M.

Color stability Color after heating Color Eiamplc 011 increase Western 30 +0.28% potassium cetyl tartrate. +0.42% magnesium cetyl tartrate +0.57% aluminum cetyl tartratc +0.50% calc um cctyl tartrate. +0.20% calcium cetyl mucatc... +0.34% potassium cetyl citrate. +0.28% magnesium cctyl citrate. +0.52% aluminum cetyl citrate. +0.50% calcium dicetyl citrate. +0.63% calcium aeicosyltartrate +0.18% calcium cetyl oxalate. +0.50% calcium cetyl succinatc. +0.50% calcium cetyl malatc. +0.50% calcium cetyl maleate. +0.34% calcium a-cicosenylsuccinate +0.15% calcium cetyl sebacate. +0.61% calcium cctyl a-aminosuccinatc +0.78% calcium cctyl malonate. +0.18% calcium a-cetenylsuccinatc. +10% potassium cetyl oxalate. +0.10% calcium cetyl scbacate. 7 4 +0.50% potassium mcetylmalonate +0.72% calcium cetyl fumarate. 5 +0.50% calcium cetylphenate+ 0.40% calcium cetyl tartrate.. +0.50% calcium cetylphcnate+ 0.50% calcium dicetyl citrate. 7 2%4- +0.50% calcium cctylphcnate+ 0.18% calcium cetyl oxalate 5 56+ +0.50% calcium cetylphenate-i- 0.t50% calcium cetyl succina e +0.50% calcium cetylphenate+ 0.50% calcium cetyl malate.. +0.50% calcium cetylphenate+ 0.50% calcium cctyl maleate. +0.50% calcium cetylphenate+ 0.10% calcium a-cetcnylsuccinate 0 +0.50% calcium cetylphenate+ 0.50 calcium a-eicosenylsuccinate 7 +0.50% calcium cetylphenate+0.15% calcium cetyl sebacate +0.25% calcium cetylpliosphate+0.40% calcium cctyl tartrate 7 +0.25% calcium cetylphosphate+ 0.50% calcium dicetyl citrate +0.25% calcium cetylphosphate+0.18% calcium cetyl oxalate +0.25% calcium cetylphosphate+0.50% calcium cetyl succinate 4 +0.25% calcium cetylphosphate+0.50% calcium cetyl malate +0.25% calcium cetylphosphate+0.50% calcium cctyl maleatc +0.25% calcium cetylphosphate+0.l0% calcium a-cetenylsuccinate 4 +0.25% calcium cetylphosphate+0.50% calcium aeicosenylsuccinate +0.25% calcium cctylpl'iosphate+0.l5% calcium cetyl sebacate +0.50% calcium cetylphenate+ 0.25% calcium cetylphosphatc+0.40% calcium cetyl tartratc 8 2+ +0.50% calcium cetylphenate+ 0.25% calcium cetylphosphate+0.50% calcium dicetyl citrate 6- +0.50% calcium cetylphenate+ 0.25% calcium cetylphospliate+0.18% calcium cetyl oxalate +0.50% calcium cetylphenate+ 0.25% calcium cetylphos phate+0.50% calcium cetyl succinate +0.50% calcium cetylphenate+ 0.25% calcium cetylphosi phate+0.50% calcium cetyl malatc lc-X f tit' rJf UEIUU TABLE IIIConti-nued peratmospheric temperatures and pressures, is

in many cases reduced or postponed by the in- Example on 0010mm" C010, corporation in the oils of the metal salts of the heatin increase g invention, particularly those carrying a polar 5 group of the character and in the position reglg g g lfi fig fgfgi ferred to repeatedly hereinabove.

phate+0.50% calcium cetyl In the tests Whose results are reported in Table maleate 6- 1% 63 5O%calciumcety1phenate+ V, the 0llS!efe11:6d to were sub ected to the oxi- 0.25% calcium cetylphosdator test particularly described In the Journal ggzf j 'g fiy gf f of Industrial and Engineering Chemistry, volume 64 +0.%0;/'g ;alciu1moetylpherIlae-F 28, page 25, 1936, at 340 R, which conditions ca cium cetyp osphatg+o 5o% calcium may be noted as extremely severe. The results 65 +0aic7os11y1succi1%aiie h 1 2a,; of the tests are reported in cubic centimeters of C clumce yp ena e 3 calcium cetylphos oxygen absorbed per 100 grams of the respec a te- 0.15% calcium cetyl tlve oils, at the periods of time indicated. se 808 8 6 2 so +1.07 diisoamyl tartrate+ 0.5 0%calciumdicety1citrate mi,- 1 TABLE V 67 +1.%7%87diisloamyl ttzllrtraiie+ ca cium co y oxa ate. 7 4 68 +1 0% vdiisoamyl mtmte+ Reductzon of oxygen absorption 0.50% calcium cctyl suc- 69 +1 "i t't't'l' 6- 23/2- IISOBJUY 81' 1'8. 6 i

0.50% calcium cetyl malate 416 1 Oxygm 3050mm 70 +10% diisoamyl tartrate+ Example 011 3;?"f fifj'ii fii?i 4 a 1 2m M 71 1.0 diisoamyl tartrate+ g gfi g flentenyl' 4% 1 25 Western 200 330 300 72 +l.o% amass-Il ness; 1 hi 0.50% calcium a-eicosenyl- 2 +0 427 -g' gg 'gi i? 3% 54 tra te f i so 200 270 73 +19% dusoazmyl tartrate+ 3 +0.57% aluminum cetyl tar- 0.l5% calclum oetyl seba- 1 tram 87 150 175 96+ 30 4 +0.50% calcium cetyltartrate 25 55. 70 calctiutq oetyl n lulcate. 18 75 p0 assium ce y cl- EXAMPLES-SET IV 7 +0 .5m 3o In many cases still further benefits may be detmtc 35 135 190 rived from the incorporation of the metal salts of 8 -iffi a will if 24 G5 93 the invention to hydrocarbon oils, by reason 3 9 +0.50% clil'c'iu'iii' iiictyTi u n I trate 2O 4O 5') of an enhanced o llness and/or an increased 10 +063% calcium wicosylmp load carrying capacity of the 0115 so compounded. iii-ate 05 105 122 ll +0.18 calcium cctyloxalate. 35 145 In the tests whose results are summar zed in m +0509c81ciumoeWlmalatefl 22 6O Table IV, the figures reported under Weeks +0.50% calcium cctylmaleate 15 150 200 Wear are those obtained in the operation of a -g gg 40 150 Weeks wear testing machine, in which a /2 inch 17 +0.34% attain aciccciiyl steel ball is pressed against a 1% inch steel cyl- 23 65 20 +0.61 calcium cetl -amlmder WhlCh is rotated at 600 R. P. M. and which nc ucciu teuuY 20 50 c0 dips into the oil being tested; the duration of 21 1%??? K}??? mo the test is 16 hours and the body of oil is held at 2e +0.25% calcium Jcctu lsuc 300 F.; the results are reported in inches of 31 +0 fi g g ggq; 8 30 wear X 10 as measured on the cylinder. The minosuccinatc 240 200 figures reported under Film strength are those obtained in the operation of a Timken machine 50 Although we have no definitely acceptable as described in the S. A. E. Journal, volume 23, page 53, 1928; the results are reported in pounds theory to offer for the success of the compositions of the invention in preventing or retarding piston at failure.

TABLE IV ring sticking and, with more particular respect W I to those compositions in which polar group subear resistance and film strength 5 stitution has been effected in the close proximity of the carbon atoms contained in the salt-form- Emmme on Weeks ing carboxyl radical, in reducing oil corrosivity 8 toward bearing metals, in stabilizing oil color at W high temperatures, in reducing engine wear, in

estern 30 288 iflgggmalcium getytltilrtratau 74 60 increasing 011 film strength and in retarding oil 0. cacium ice-y citrate. 02 120 r +OJ87: calcium cetyloxalate 102 m oxid z ability at h gh temperatures, aswell as In a igggg, calc um cetylmalatetau. 83 .500 stabilizing in these and other ways oils already ca clumce y me ea e 200 15 +0507; calcium wcetylmalm compounded with agents not of this nvention, nate 143 100 and do not, accordingly, Wish to be limited by 17 m6 220 5 an theory which, at some more advanced stage 25 +0.2Q%tecalcium a-cetenylsucin the development of the art, might prove ques- 35 t}: g g 5 tionable or untenable, w nevertheless wish'to calclum dwetyl point out, in connection with the examples above trate 108 320 d th t t 1 t B te dinaPhthe. an e few yplcal struc ura represen a ions F39 below the manner in which the results brought 1) 0.50 l .t t 10 70 %cacmmcp ylphena e 5 about by the practice of the invention are considered b us now to be attributable to the osi- EXAMPLES-SET v y p Still further, the capability of hydrocarbon oils to absorb oxygen, when exposed thereto at sution occupied by the designated polar groups, with respect to the salt-forming carboxyl group 75 of the molecule.

TABLE VI Structures, with particular relation to polar Structure 7 R 0 CHO OHHCOHC 0 OK (ROOC-HOOHHCOHCOO)2Mg (R00OHCOHHCOHOOO)1A1(OH) Calcium alkyl mucate (R0 0 C-HO OH-HC OH-HC O H-HC OH-C O O):Ca

7 Magnesium alkyl citrate EzC--C 0 O R R0 0 C-CH:

HOG-000R ROOC-COH H2 -C 0 0Mg0 0 C-CHa 8 Aluminum alkyl citrate H9CC O O R R0 0 C-CH;

HOCCOOR ROOC-COH HzC-C O OllAlO O C-CH:

10 Calcium a-eicosyltartrate C O O l HO OH H H I Ca Ha1C1a-CCC 0H C O O 11 Calcium alkyl oxalate R0 0 0 (I70 0 R C O 0Ca0 O C 12. Calcium alkyl succinate R0 0 C ('30 0 R I Hz (3H: (3H1 (EH; 0 O 0-Ca-O 0 C 13 Calcium alkyl malatc R0 0 C C O 0 R HCOH HOOK HCH HCH C O O-Ga-O 0 C 14 Calcium alkyl maleate R0 0 C C O 0 R C C II II E C O 0-Ca-O 0 C 15 Calcium wslkylmalonate /C O O RCH Ca C O O 16 Calcium a-cctenylsuccinate.. (130 O HIHCH-C=CCH I I C O 0 1s Calcium alkyl sebacate R0 0 c c 0 o R (0H,). (CH1):

C O O-C a0 O 21 Calcium alkyl malonate R0 O(l3 O R CH: Hz? 0 O-Oa0 0 C The above few typical representations will sufiice to enable all of the earlier and numerous 5 among themselves with respect to the degree of additional individual members of the agents contheir capabilities to retard other types of dete templated for incorporation in the compositions riorations, as for example corrosivity toward of the invention to be studied in connection with bearing metals, retardation or inhibition of cortheir above exemplified efiects when so incorrosivity brought about by the additional presporated. ence of another type of compounding agent, sup- In consideration of the effects as exemplified pression of the formation of color bodies, and the and in view of the structures as indicated, it is like. It is believed, at the present state of our permissible to generalize briefly as follows: knowledg of these phenomena, that the pres- While all of the agents of the invention are effecence of a polar group additional to the salttive to prevent such deterioration as is evidenced T forming carboxylic acid group, such as --COOH,

by piston ring sticking, they differ considerably afar OH, COOR, NH2, and the like, as above listed and exemplified, in a position in close proximity to the carbon atom of the salt-forming carboxylic acid radical, is the means by which these highly beneficial eiiects are brought about, and that the efiectiveness of the polar group or groups decreases as their distance from the saltforming carboxyl radical increases. It must be noted, however, that the polar group or groups so present or introduced must not be capable of splitting out, to form a corrosive acidic substance, and such groups as -Cl, Br, --I, -F, OSO2OR, and OSO(OR) are accordingly not contemplated as within the designation of polar group or radical as the same is employed herein for the purposes of this invention.

Generally, measurable improvements in the properties of hydrocarbon oils are obtained by the incorporation of as little as 0.1% of the agents of the invention, but amounts between about 0.2% and 2.0% of the agents, by weight based on the oil, are preferable, dependent upon the degree of inherent tendency toward degradation of the oil itself or as otherwise compounded: amounts higher than about 5.0% are regarded as unnecessary in the best practice of the invention.

A feature of the invention is in the preparation and distribution of bases or concentrates containing relatively large proportions of the additive agents in admixture with hydrocarbon oils of the lubricating or less viscous types or, if more suitable in conjunction with certain of the agents, by reason of solubility relationships or the like, in admixture with aromatic hydrocarbons or withalcohglaesters, ketones or ethers. generally of the aliphatic series. Admixtures of the agent's and lubricating oils or other solvents or carriers containing upward of 50% of the essential'agents, by weight, may be thus prepared and distributed, for later blending with the particular lubricating oil media desired to be put to use, as occasion demands. In the preparation of either the finished oils of the invention or the base or concentrates referred to. complete or clear and homogeneous solution is not always necessary: blending agents or homogenizers may be employed if desirable. to prevent sedimentation of the more oil-insoluble of the agents, but it has been found the possible detrimental effect of the presence of filterable insoluble materials of this character, if indeed present, is determined largely by the particular conditions attending the contemplated use, and

that their presence is not in all cases deleterious to the functioning of the compositions in their intended manner.

While the character of the invention has been iven in detail and numerous illustrative examples of the preparation and utility of the compositions of the invention have been described, this has been done largely by way of illustration and with the intention that no limitation should be imposed upon the invention thereby. It will be obvious to those skilled in the art that numerous modifications and variations of the above illustrative examples may be effected in the practice of the invention. which is intended to be of the scope of the appended claims.

We claim:

1. A l quid hydrocarbon oil of the lubricating oil class, normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines. containing di'ssolved in the oil a small amount, sufficient to retard the said deterioration, of an oil-soluble metal salt of an acid of the type in which n is a whole number and in which hydrocarbon radicals may replace one or more of the hydrogen atoms of the CH2 groups, and in which at least two polar radicals have been substituted for hydrogen atoms carried by carbon atoms other than that of the salt-forming carboxylic acid group.

2. A liquid hydrocarbon oil of the lubricating oil class, normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines, containing dissolved in the oil a small amount, sufficient to retard the said deterioration, of an oil-soluble metal salt of an acid of the type ating temperatures encountered in the lubrication of internal combustion'engines', containing an oil-soluble metal salt of an acid of the type HOQCT (CH2) n-CQOIL. innwhiclnngismhwhole number greater than 1 and in which. hydrocarbon radicals may replace one or more. of the hydrogen atoms of the CH2' groups, and in which at least two polar radicals have been substituted. for hydrogen atoms carried on carbonatoms at least one of which is placed not farther'than' the gamma, position relative to the carbon atom of the salt-forming carboxylic acid group, the said polar radicals being incapable of forming a corrosive acidic product when split out from the said position upon exposure to superatmospheric temperatures in the presence of the hydrocarbon oil. said metal salt being dissolved in the oil in small amount suflicient to retard the said deterioration. 4. A liquid hydrocarbon oil of the lubricating oil class, normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines, containing a small amount. suflilcient to retard the said deterioration, of a polyvalent metal salt of a partially-esterified acid of the type HOOC( CH2) ni-COOH in which n is a whole number, and in which at least one OH and at least one other polar radical are substituted for hydrogen atoms of the said (CH2) groups.

5. A liquid hydrocarbon oil of the lubricating oil class. normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines, containing a small amount, suflicient to retard the said deterioration, of a polyvalent metal salt of a partially-esterified citric acid.

6. A liquid hydrocarbon oil of the lubricating oil class, normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines, containing a small amount, sufiicient to retard the said deterioration, of a polyvalent metal salt of a tartaric acid in which one carboxyl group is esterifled.

7. An improved liquid hydrocarbon composition comprising a major proportion of hydrocarbon lubricating oil subject to deterioration at operating temperatures encountered in the lubrication of internal combustion engines and a minor proportion, sufiicient to inhibit said deterioration, of a metal salt of an aliphatic polycarboxylic acid having at least two carboxyl groups and at least two additional polar groups on alkyl carbon atoms at least one of which is not farther than the gamma position relative to a carboxyl group of said acid, said acid having no more than eight alkyl carbon atoms between the nearest two carboxyl groups thereof and containing an oil-solubilizing substituent.

8. An additive for lubricants capable of in hibiting deterioration of a hydrocarbon oil at operating temperatures encountered in the lubrication of internal combustion engines, comprising a concentrated solution in a viscous oil of an oil-soluble metal salt of an aliphatic polycarboxylic acid having at least two carboxyl groups and at least two additional polar groups on alkyl carbon atoms at least one of which is not farther than the gamma position relative to a carboxyl group of said acid, said acid having no more than eight alkyl carbon atoms between the nearest two carboxyl groups thereof and containing an oil-solubilizing substituent, said solution being capable of dilution with mineral'lubricating oil to form a homogeneous mixture containing from approximately 0.1% to 2% by weight of the salt based on' the total amount of lubricating oil.

9.'A liquid lubricating oil composition comrising a hydrocarbon oil in major part; about I1to"5%bf'we1ght based on the hydrocarbon oil and sufficient to inhibit corrosiveness of the finished oil toward bearing metal alloys of the type of copper-lead and cadmium-silver alloys of a. metal salt of an. acid 01 the type in which n is a whole number from 1 to 8 inclusive, in which at least two of the hydrogen atoms of the -CH2- groups are replaced by polar groups and in which one or more hydrogen atoms of the CH2 groups may be replaced by hydrocarbon radicals; and about 0.1 to 5% by weight based on the'hydrocarbon oil of a metal salt selected from the group consisting of metal alcoholates and metal phenates.

10. The oil of claim 9, wherein the first named metal salt is a polyvalent metal salt and the second named metal salt is an oil-soluble polyvalent metal phenate.

11. The oil of claim 9, wherein the first named metal salt is a polyvalent metal salt and .the second named metal salt is an oil-soluble alkaline earth metal salt of an alkylated phenol.

12. A liquid hydrocarbon oil of the lubricating oil class, normally tending to deteriorate at operating temperatures encountered in the lubrication of internal combustion engines, containing a small amount, sufiicient to retard the said deterioration, of a polyvalent metal salt of a half ester of mucic acid.

13. A lubricating oil comprising, as the major ingredient, a petroleum lubricating oil and containing about 0.1 to 5 per cent by weight based on finished oil of an oil-soluble alkaline earth metal salt of a partially esterified citric acid.

14. The oil of claim 13, wherein said alkaline earth metal is calcium.

151A lubricating oil comprising, as the major ingredient, a petroleum lubricating oil and containing about 0.1 to 5 per cent by weight based on finished oil of an oil-soluble alkaline earth metal salt of a partially esterified tartaric acid.

16. The oil of claim 15, wherein said alkaline earth metal is calcium.

'17. A lubricating oil comprising, as the major ingredient, a petroleum lubricating oil andcontaining about" 0.1 to 5 per cent by weight based on finished oil of an oil-soluble alkaline earth metal salt of a partially esterified mucic acid.-

18. The oil of claim 17, wherein said alkaline earth metal is calcium. 1