US2450633A - Compounded oil - Google Patents

Description

Patented Oct. 5, 1948 COMPOUNDS!) 0114 James 0. Clayton, Berkeley, Calif alsignor to California Research Corporation, San Franoisoo, Calif a corporation of Delaware No Drawing. Application October 31, 1944 Serial No. 561,317 c dclaiml.

This invention relates to lubricants and the like. more particularly, to crankcase lubricants such as those used in the ordinary motor car, in aircraft engines and in Diesel engines.

crankcase lubricants are required to maintain lubrication of pistons under severe conditions. Temperatures are such and the oxidizing character of the combustion gases (which are hot and under pressure) is such that mineral lubricants decompose forming products which are corrosive and products which ioul the piston, interfere with passage of lubricant through the openings in the oil ring and cause sticking. of piston rings. In certain types of service, as in heavy Diesel engines, straight mineral lubricants, regardless of selection of crude oil and regardless of the refining procedure, will not stand up under the conditions imposed for a reasonably long period of operation. Added to the eiiects of lubrlcant deterioration are deposits formed by the fuel used to operate the engine.

It is now a common practice to add to mineral lubricants one or more agents adapted to stafbilize the oil. reduce the amount oi deposits on'fl pistons, etc. Seldom is it suilicient, howeverfto add only. one type of addition agent. 'Thus a strongly detergent addition agent (that is, an

addition agent which promotes engine cleanliness) may not adequately stabilize the oil and may allow development of corrosive oxidation products in the oil. Many detergents are'corrosive to cadmium-silver bearings and certain of them cause the oil to foam excessively under conditions of violent agitation with air and at low pressures.

It is an object achieved by the present invention to provide a combination of addition agents for lubricating oils and the like which is inexpensive and at the same time eilects substantial improvement of the oil.

It is a particular object achieved by the present invention to provide a crankcase lubricant suitable for heavy duty use which combines high detergent qualities, low corrosiveness and reduced ioaminess.

These and other objects will be apparent from the following description and the claims.

I have discovered that lubricating oils and the like can be greatly improved by adding thereto 2 a salt of a sulfonic acid and a salt of a thiscarbamic acid.

The base oil to which the sulfonic and thiccarbamic salts are added will usually be a petroleum oil of lubricating viscosity. It may range in viscosity from spindle oils to cylinder stocks; it

may be from a paraiflnic, naphthenic or mixed base crude petroleum; it may be refined by any or several of various methods. may be a distillate or residual oil, etc.

However. the base oil may consist in whole or in part of other oils, such as certain vegetable oils (e. g., castor oil. sperm oil) polymerized oleiins, oils synthesized from coal or oxides of carbon, amyl naphthalene, etc.

The sulfonic acid whose salt is added to the base ,oil (or formed in situ) may be a pure compound but will usually be a mixture. often a complex mixture of sulfonic acids. The so-called mahogany acids are preferred. These are high molecular. weight, oil-soluble acids formed in the refining oi mineral lubricating ofls with strong or fuming sulfuric acid to produce medicinal or technical white oil. On heavy treatment of such mineral oil with sulfuric acid two phases are formed, one of which (the lower, heavy layer) is a sludge and the other (the upper layer) consists of the treated oil containing the mahogany acids. The sludge contains the so-called green acids, which are water-soluble as distinguished from oil-soluble acids. The mahogany acids may be recovered from the oily phase by various methods. Thus the oily layer may be extracted with aqueous methyl, ethyl or isopropyl alcohol to extract the mahogany acids. Or the oily layer may be neutralized with aqueous alkali and the alkali metal mahogany sulfonates extracted with aqueous methyl, ethyl or isopropyl alcohol or aqueous acetone.

Methods of recovering mahogany acids and their alkali metal salts are well known in the art and further elaboration is not required here except to note that, in connection with the pres-' though suli'onic acids of molecular weight of 350 or lower can be used in certain types of service. By aliphatic type su-lfonic acids is meant sulionic acids in which at least about 50 per cent by weight of the sulfonic acid consists oi aliphatic carbon and hydrogen; it does not mean that the sulfonic acid is necessarily a true allphatic sulionic acid wherein the suifonic group or.groups is or are attached only to aliphatic carbon. Thus, besides the mahogany sulionic acids there may be used benzene, naphthalene and other sulionic acids in which one or more oil solubilizing, preferably long chain allryl substituents are attached to the aromatic nucleus. Examples of such aliphatic substituted aromatic sulforiic acids are the salts of cetyi benzene sulfonic acid, cetyl naphthalene sulfonic acid, the sulionic acids described in Flett; United States Patent No. 2,283,199, and other sulionic acids repared from aromatic hydrocarbons containg aliphatic radicals derivable from petroleum.

Although nitrogen base and alkali metal sulfonates may be used, polyvalent metal sulionates are preferred and of the polyvalent metal sulfcnates those of the more basic metals, such as magnesium, calcium, strontium andbarium are preferred.

Examples of sulionates that may be used in accordance with the invention are lithium, potassium, sodium, calcium, barium, aluminum, zinc, tin and lead mahogany sulfonates, cetyl benzene sulionates and cetyl naphthalene sulionates; the corresponding salts of the sulionic acids described in Flett, United States Patent No. 2,283,199; the corresponding salts of sulfonic acids prepared from aromatic hydrocarbons containing aliphatic radicals derivable from petroleum; and true allphatic sulionates, ,such as lithium, potassium, sodium, calcium, barium, aluminum, zinc, tin and lead sulfonates derivable from the product of condensing chlorinated petroleum wax with sodium acid sulfite.

A solution of calcium mahogany sulionate in lubricating oil can be prepared as follows: Take an acid treated oil, preferably at a late stage in the acid treatment and extract the sulfonic acids from the oil by means of ethyl alcohol. Add a petroleum thinner and water to the alcoholic extract and allow the aqueous phase and the petroleum thinner phase to separate; the latter phase will contain the suli'onic acids. Add to the petroleum thinner solution of sulfonic acids, calcium hydroxide in quantity suilicient to neutralize the sulfonic acids and lubricating oil in quantity suflicient to prepare a concentrate oi the resultant calcium sulfonate. Filter the mixture and remove the light solvent by distillation, leaving a residue of lubricating oil in which the calcium suli'onate is dissolved.

The thiocarbamates, which form the second component of the compounding of the invention, may be represented generically by the formula The preferred thiocarbamates are the polyvaient metal dithiocarbamates in which R1 and R: are both hydrocarbon or substituted hydrocarbon groups which are suillciently large v(e. g., 4 to 20 carbon atoms each) to impart oil solubility to the dithiocarbamate, or in which R1 and R: are a single bivalent hydrocarbon group as in the petroleum base" dithiocarbamates discussed hereinbelow. The preierred polyvaient metals are zinc and cadmium. Among other metals that may be used are lithium, sodium, potassium, magnesium, calcium, strontium, barium, aluminum. tin and lead.

The dithiocarbamates may be looked upon as derivatives of amines and carbon disulflde, since the usual method of preparing them is by reacting an amine with carbondisuliide and caustic alkali:

The various polyvalent metal dithiocarbamates may be prepared from the alkali metal dithiocarbamates by double decomposition. The preferred dithiooarbamates may, therefore, be regarded as polyvalent metal dithiocarbamates derived from secondary amines and containing a suiliciently large hydrocarbon group or groups to render the salts oil-soluble. The secondary amine or which the salt is a derivative may be an allphatic amine (di-alkyl, di-cycloalkyl. mixed alkyl-cycloalkyl, eta), an aromatic amine or a mixed aliphatic-aromatic amine and it may be an amine such as piperidlne or itshomologues in which the secondary nitrogen atom is part at a heterocyclic ring.

Illustrative examples oi'thiocarbamates that may be used in accordance with the invention are calcium, lead, zinc and cadmium dibutyl dithiocarbamates; zinc methyl octyl dithiocarbamate; zinc dicetyl dithiocarbamate; sine diamyl thiolcarbamate; sinc diamyl thionocarbamate; zinc monocetyl dithiocarbamate: zinc butyl amylphenyl dithiocarbamate; calcium di- (cyclohexylphenyl) dithiocarbamate; calcium, zinc. cadmium and potassium "petroleum base" dithiocarbamates; zinc dibenzyl dithiocarbamate; zinc di-(cetyl- 'phenyl) dithiocarbamate; and zinc di-(amylpiperidyl) dithiocarbamate.

General methods of preparing thiocarbamates are available in the literature. The best method presently available for preparing dithiocarbamates is that method in which a primary or secondary amine is allowed to react with carbon disulilde and aqueous or alcoholic caustic soda or caustic potash. producing an alkali metal dithiocarbamate. This may be recovered by crystallization, but since the polyvalent metal salts are preferred, it will be the usual practice to add an aqueous solution or a water-soluble polyvalent metal salt, such as calcium chloride or line sulfate, to the reaction mixture (diluted with water it necessary) containing the alkali metal dithiocarbamate, thereby precipitating the desired polyvalent metal dithiocarbamate. This may be purifled by crystallization from a suitable solvent, such as a light hydrocarbon thinner. Alternatively, to an aqueous solution or alkali metal of dithiocarbamate may be added petroleum thinner and to the mixture may be added an aqueous solution or a polyvalent metal salt. thus precipitating 5 polyvalent metal dithiocarbamate from aqueous acsasss 5 a solution and forming a solution of the same in petroleum thinner. General methods of preparing monothiocarbamates (which are of two types: thiolcarbamates.

and thionocarbamates, I

mmN-c-o-M) are available in the literature; e. 8.. thlolcarbamates from amines and COS.

The preparation of petroleum base dithiocarbamates is described in detail in Miller and Rutherford application, Serial No. 441,064, filed May 6, 1942 (now Patent No. 2,363,012, dated November 21. 1944). Briefly stated. the "petroleum base" dithiocarbamates are prepared by extracting the nitrogen bases from nitrogen-containing cracked naphtha or the like, reducing the bases and reacting the reduced bases with carbon disulfide and caustic alkali to produce the alkali metal "petroleum base" dithiocarbamates, from which the polyvalent metal "petroleum base" dith'iocarbamates can be prepared by double decomposition.

From the properties and reactions of the reduced, cracked petroleum nitrogen bases from which the aforesaid "petroleum base" dithiocarbamates are derived, it is believed that they are complex mixtures predominating in piperidine derivatives. also containing tetrahydro quinoline (reduced nitrogen ring) and/or its derivatives. These bases contain alkyl substltuents, such as methyl, ethyl and propyl substituents, on the carbon portion of the ring. The dithiocarbamates produced from these bases, that is, the aforesaid "petroleum base" dithiocarbamates. are, therefore, believed to be a mixture of compounds of the formula Gila-Cg: B N-- -S-.M

CHr-C 1 wherein M is a metal and one or more of the hydrogen atoms are substituted by short alkyl groups (about 01 to C5) and/or by a condensedents on the carbon part of the ring. may also beused according to the invention.

The sulfonates 'hereinabove described may be used in oil in proportions of 0.1 per cent or less to 5 per cent or more, about 0.5 to 1.5 per cent being preferred, and the thiocarbamates may be used in oil in proportions of 0.1 per cent or less to 2 per cent or more, about 0.5 to 1.5 per cent being preferred. All percentages so stated are by weight based on finished oil. Concentrates of sulfonate and thiocarbamate in oil may be prepared for later blending with more oil to produce the finished lubricant; for example, concentrates containing 10 to 50 per cent of sulfonate and 10 to 50 per cent of thiocarbamate, such percentages being by weight based on total concentrate.

fonate. have been heretofore proposed as motor oil detergents. They are. however. unduly corrosivo toward hard alloy bearings suchv as cadmium-silver and copper-lead bearings and they do not satisfactorily inhibit gum formation and deposition in piston rins slots. etc. I have found that the sulfonates. such as calcium mahogany sulfonate. are considerably improved in these respects by the use o f thiocarbamates. such as zinc "petroleum base dithiocarbamates and zinc dibutyl dithiocarbamate.

' The following specific examples will serve to illustrate the advantages obtainable by and the preferred manner of practicing the invention.

Example 1-Lauson engine tests-Various oils were subjected to test as crankcase lubricants in single cylinder Lauson gasoline engines of the kind described in Parrington et al. U. 8. Patent No. 2,325,597. Engines were operated at 1200 revolutions per minute. 875 1''. jacket temperature, 300 1''. oil temperature and for 60 hours. After each run the engine was disassembled, inspected, cleaned and reassembled.

The manner of testing may be illustrated as follows: Assume that three oils designated as I, II and III are under investigation. These oils are tested in the same engine; also tested in the same engine is a "reference oil," which is a standard, commercially available heavy duty lubricant containing as compounding agents a metal phenate and a metal organo phosphate. The first run in the engine is with reference oil. then oils I. II and III are tested in that order, and, finally. the reference oil is again tested.

It is now known that an engine changes its characteristics during operation; thus an engine that has been run 60 hours will not, even though disassembled, cleaned and reassambled, give the same performance with a fresh quantity of the same lubricant. To avoid as much as possible errors in comparing oils due to the aforesaid change of engine characteristics. the following plan was used.

Suppose the "piston discoloration number" (PD No.), which is a form of rating crankcase lubricants explained in detail hereinbelow. of the reference oil when first tested is 200, the PD Nos. of oils I, II and III are 150, 1'15 and 200, respectively, and the PD No. of reference 011 when last run is 250. An interpolated reference oil PD No. is calculated for each of the oils I, II and III. It is assumed, since the same engine gave a PD No. of 200 before oils I, II and III were run and a PD No. 250 afterwards, or a diiference of 50 PD No. units, that if at the time oil I was actually tested the reference oil had been used, the PD No. of reference oil would have been 200 plus one fourth of 50 or'212.5; similarly. that the PD Nos. of reference oil if used at the times oils I11 and III were used would have been 225 and 237.5, respectively. From these interpolated PD Nos. of reference oil and from the actual PD Nos. of oils 1, H and III are calculated PD No. diil'erences, each of these being the difference between the actual PD No. and the corresponding interpolated PD No.. the diflerence being positive if'the actual PD No. is greater, negative if it is smaller than the interpolated PD No.

This manner of rating oils is more accurate than a manner of rating which simply compares actual PD Nos.. for it corrects in part at least for changed characteristics of the same engine and it makes more reliable the comparison of PD The sunonates. such as calcium mahogany sul- Nos. obtained in different engines.

7 "PD No.," an abbreviation of "piston discoloraticn number," hereinabove and hereinbelow referred to, is arrived at in this manner: The engine is run as described for hours. Then it ute to the more water-soluble, less oil-soluble character of the sulfonate.

, Example Zr-Full scale engine tests-Tests were carried out in two types of full scale engine showing than the base oil. This result we attribis disassembled. The piston skirt is inspected using as crankcase lubricants the preferred oils visually. To a piston skirt which is completely of the invention. The said engines and the conblack is assigned a PD Noiof 800; to one which ditions of operation were as follows: One engine, is completely clean is assigned a PD No. of zero; preferred to herein as the "L-i' engine, was a to those intermediate completely black and comsingle cylinder, 5%" bore Diesel engine; it was pletely clean are assigned PD Nos. in proportion run for 480 hours at 1000 revolutions per minute. to the carbonaceous deposits. Actually, further at a load of 10.8 brake horse power, oil temperarefinements were employed in arriving at PD Nos. tureof 145-150 F., jacket temperature of 175- hereinbeiow disclosed. but since the same method 180 It, oil change at 120 hour intervals. The was used in every case it is unnecssary to describe other engine, herein referred to as the, Ii-3" enthese refinements. gine, was a 4 cylinder. 4%" bore Diesel engine Results obtained with various oils are set forth which was run for 120 hours at 1400 revolutions in Table I below. per minute, BHP of 3'7, oil temperature of 210- Tablel i i'ii' t'u Film m. 35' Sulionlto Additive m Dithiooarbamate Additive m per figg'g;

- Ki 0 am Kilogram of u tron OI mahogany suliouste r 1 Zn petroieum bale'. eltnitmttmtttu' so i06 i 14 0 so -115 -do 1 Zn dihutyldithioearhamate so 0 Ba mahogany suiionsts I 14 Zn "petroleum bass" dithiooarbamate- -i00 'Os "petroleum iatsri" benol sulionate. 15 in 20 l Ca "petroleum slu gs" sul costs... 14 f 1) +215 Ca ietra-smyl suli'onate... 14 .d.o 20 +75 Ca mahogany sulionatell 14 M so 205 Cs "petroleum alkylsted" benzene lulionate. is o 00 M& I +400 to +500 I No Compounding.

In Table I above. base oil A designates an SAE 214 F., jacket temperature of 198-202 R, no grade blended oil. a blend of solvent treated oil change. California naphthenic base oil and California par- Results are given in Table II below. afilnic base oil. Base oil B designates a straight Table H SAE 30 grade California paraflinic base oil. The concentrations are expressed as miliimols of metal per kilogram of compounded oil; thus, I millimols as A 8 of Ca mahogany sulfonate I and 20 millimols of zinc "petroleum base" dithiocarbamate mean fi' fg 3 3mm No 0.007 and 0.020 gram mols of calcium (in form a Belt m M m of sulfonate) and zinc (in form of dithiocarbamm 6 atg) per kilogram of 31,] 0 Top Ring Groove De- Thin to Mad -1 Med to Hvy.

The calcium mahogany sulfonate I was the cal- H5, o 1 cium salt of a mahogany acid obtained in the l m 1 sulfuric acid treatment of a blend of asphaltic io g 'gfim and paraflinic base oils to produce white oil; caiest: cium mahogany sulfonate II was the calcium salt as "m2sr'?iiifir%i i s: it'ii: d gd zrste.

of a mahogany acid obtained in the sulfuric acid 9% y"; 37 treatment of a paraiiinic base oil to produce white with sr oil; the calcium "petroleum alkylated benzene andphenol sulfonates were the calcium salts of on A consisted of base n Table 14 c sulfonic acids produced from benzene and phenol, go mahogany Sultanate and 1% zinc a 32 l'especflvelythat had been d f base" dithiocarbamate. Oil B differed from oil White 011; and the calcium Petroleum Aonlyinthat it contained haliasmuch sulfonate. sl d 1111 11 w the calcium Salt of u 'The reference oil was the same as described in fonated phenol extract of petroleum, said sul- Example 1, muted extract being 9 Water-soluble Ind The same three oils were also-subjected to 'a less oil-soluble character than mahogany'sulfonlc foaming t t-1 which oil is pumped from the mldflcrankcase of a 1% horsepower Wisconsin single I It is pparent from Table I that the sulfonatecylinder air-cooled gasoline engine to an evacudlthlocalbamate mp ndin greatly imp v ated flask where the height of foam is measured, h base 011 and in most ases yi a uch 7e thence back to the crankcase. From data oblower PD'NO. than the reference 11- I 1 8- served in this test a foamindeiv' is calculated. niflcant that the calcium "petroleum sludge" sul- This foam index measures both the foaminess of fonate-zinc "petroleum base dithiocarbamate an oil at an absolute pressure of 5" mercury and compounding made a poor showing compared the extent to which the pressure can be reduced with the reference 011, although a much better before foaming becomes universal throughout the body of oil in the flask. R su ts, both in height of foam and.i'oam index, are given in Table III below.

Table "1 Height oi loam in inches at 5" marcury absoluteprecaurc 2.0

1.8 3.6 Foam index 8.0 1.2 85-}- Further examples of compounded oils'ot the invention are as follows:

Iteierencc on n on 5 major proportion of a petroleum oil of lubricating viscosity, about 0.1 to 5% by weightbased on finished oil of an oil-soluble alkaline earth metal Base Oil Sultanate Thiocerbamate BAE hthenic oil 1 Ba 1 Zn lcum base" dithiocal'bamato. SAE war afiinic oil. l Camah y sulionate 1 0. 531.: base" dithiocarbamate, BAE 30 mixed base oil 1 Ca out 1 t. mnmn i 1, Ba butyl dithiocar bamate. SAE 30 Pennsylvania oil- 1 a Ca ogany sulionate i 0d "petroleum bale dithiocarbamate.

ofls, more particularly with crankcase lubricating 25 oils; however, the employment of the compounding agents of the invention in other lubricants, in

transformer oils, in greases, etc., is contemplated.

I claim:

0 high molecular weight aliphatic type alkaryl sulionate and about 0.1 to 2% by weight based on finished oil of an oil-soluble zinc dithiocarbamate.

5. The petroleum lubricating oil 0! claim 4 wherein the alkaline earth metal is calcium.

6. A petroleum lubricating oil comprising a major proportion 01' a petroleum oil oi lubricating viscosity, about 0.1"to 5% by weight based on finished oil of calcium mahogany sulfonate and about 0.1 to 2% by weight based on finished oil 1. A petroleum lubricating oil. comprising a so of zinc "petroleum base dithiocarbamate.

major proportion of a petroleum oil 0! lubricating viscosity, about 0.1 to 5 per cent by weight based on finished oil of an alkaline earth metal mahogany sultonate and about 0.1 to 2 per cent JAMES o. CLAYTON.

REFERENCES CITED The following references are or record in the by weight based on finished oil of zinc "petroleum m of t patent:

base" dithiocarbamate.

2. A petroleum lubricating 011 comprising a major proportion of petroleum oil of lubricating viscosity, about 0.1 to 5 per cent by weight based on finished oil of an oil-soluble calcium higher 40 2,265,851

alkaryl sulfonate or above about 500 molecular weight and of the aliphatic type in which at least by weight or the sulphonic acid consists of aliphatic carbon and hydrogen and about 0.1 to

UNI'I'ED STATES PATENTS Number Name Date 2,100,880 Loane June 8. 1989 llatheson Dec. 0, 1041 2,343,393 Bergen Mar. 7, 1944 2,361,478 Higbee Oct. 81, 1944 2,386,539 McCleary Jan. 2, 1945 7 Patent No. 2,450,633.

Certificate of Correction October 5, 1948.

I JAMES O. CLAYTON It is hereby-certified that error appears in the printed specificetion of the above numbered patent requiring correction as follows:

Column 10 lines 20 and 21, claim 4, strike out high molecular weight aliphatic typealkarylsuifonate and insert instead higher alkaryl sulfonate 0 above about 500 molwular weight and of the aliphatic type in which at least 50% by weig t of the sulphonic acid consists of aliphatic carbon and hydrogen; and that the'said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

, Signed and sealed this 25th day of January, A. D. 1949.

I [out] THOMAS E. MURPH Alcictmit 0mm; Patmtl.