US2336074A - Lubricating oil - Google Patents

Description

partly oxidized e oil,.and

Patented Dec; 7, 1943 UNITED .s'r

LUBRICATING on.

Elmer W. Cook, New York, N. Y., and William D.

Thomas, American N Drawing This invention relates to improved oils, particularly lubricating oils of the crankcase type. Although lubricating oils oi. the present inven tion are highly desirable for use in crankcases of passenger automobiles they are especially valuable for heavy duty use in truck, bus. aeroplane, marine and Diesel engines which operate for long periods of time at high temperatures.

The principal objects of the invention are to provide a lubricating oil of ,the heavy duty type In, Stamford, Conn., assignors to d Company, N. Y., a corporation of Maine Application May 16, 1942, erial No. 443,307

which is resistant to oxidation and sludge forperiods of time, as inheavy duty service, they tend to decompose with the formation of complex-and objectionable oxidation and decomposition products. Under the high temperature con- 1 ditions prevailing in the engine these decomposition products polymerize to form lacquer-like deposits on or between the moving parts causing these parts to stick. Even larger quantities of polymerization products remain dispersed in the v are readily precipitated to form a sludge when'the i cools or when fresh oil is added to the heated metal surfaces and cut down. the eflective life or the en ine.

A number of oil soluble detergents oi the type oi metal soaps, phenolates and aicohoiates have These precipitated sludges becomeasked on been proposed and used in crankcase oils to dis-I solve or disperse the sludge and prevent lacquer deposits and stuck piston rings. Unfortunately,

however, the great maiority 01 these substances increase the rate of oxidation and their presence results in an increased concentration of acidic.

oxidation products in the .oil. Increased quantitles of these acidic oxidation products. in the oil create'in turn aneve'n more serious. difficulty for they attack and corrode alloy bearings commonly employed in internal combustion engines. Alloys composed of copper-lead, silver-cadmium. nickel-cadmium. etc. are widely-used and are subject to attack by the acidic oxidation prod ucts iormed in the oil. 7

Certain anti-corrosion agents which have no detergent properties, have been added to lubrieating oils in order to counteract the corrosive eflect of the oxidation .products of the oil. Although many of the detergents and anti-corrosion agents which have been previously mentioned perform their individual functions in lubricating oils the two separate additives do not cooperate-to produce a satisfactory anti-corrosion and detergent action when used together. The function of a corrosion inhibitor is to cover the bearing surfaces and other corrodable parts of theengine with a passivating film that prevents corrosion of the metal by the organic acids and other corrosive products of the oil.- A detergent, as its name implies. operates to remove adhering solids in the metal parts of the engine and thus produce a clean metal surface. Consequently mixtures of detergent with a corrosion.

.inhibitor have proven to be ineflective over-any extensive period of time since the deternt action of the sludge inhibitor tends to remove the corrosion inhibitor from the metal suriacethusf rendering it ineffective for the purpose intended.

sulfides and salts thereof avoid the above-described difliculties by e a i notonlyexcellent corrosion inhibiting properties but detergent characteristics, thus enabling us to provide a' lubricating oil having a 1 e additive eflective to inhibit corrosion, sludge and v forma-.

tion, ring sticking and other cuities ienced with lubricating oils-s in a heavy duty capacity. These compounds are also extremely heat stable and are not decomin the-oil at the high operating temperaoiten encountered. They are also practicallywater insoluble and are not extracted from the oil by contact with water nor do they tend to promote the formation of emulsions with water in the oil.

Another advantage to be obtained by our use of bis-(ZA-dialkyi phenol) -e-alkyl phenol sulfides or their salts lies in their soiubilizing action on certain materials whichare known to be good detergents, anti-oxidants, etc. or have good corrosion inhibiting properties but which cannot ordinarily be used because of their oil-insolubility. Certain dithiophosphates, such as di-(p-tertiary Y amylphenol) dithiophosphate; calcium. barium. aluminum, zinc and magnesium stearates. palmitates. naphthenates, etc. are diflicultly soluble in lubricating oils but'because of their solubility in the compounds describedherein it is possible to The bis-(ZA-dialkyi phenol) -d-alisyl phenol ciently large to be effective.

The bis-(2,4-dialkyl phenol) -.4alkyl phenol 1 sulfides and salts thereof employed by us in preparing our improved lubricating oils are new chemical compounds and may be represented by the general formula:

i. i .L l J.

in which R, R1 and R2 are alkyl radicals, n is the small whole number 1 or 2 and m is the small whole number 1 or 2, Me is hydrogen or a salt--v forming radical and X is the valence of Me. These compounds are described and claimed in our copendin-g application, Serial No. 443,306,

filed May 16, 1942.

The bis-(2,4-dialkyl phenoD-4-alkyl phenol sulfides and salts thereof illustrated by the general formula above may be prepared by reacting mixtures of 2,4-dia1kyl phenols and 4-alkyl phenols with sulfur dichloride (S012) or sulfur monochloride (S2012) depending upon the type of sulfide desired as the reaction product. The salts of these compounds may be prepared from the re sulting reaction product as ll be described hereinafter.

When reacting two molecular proportions of 2,4-dia1kyl phenol with one mole of 4-alkyl phenol and sulfur dichlorida'for example, bis-(2,4- dialkyl phenol) -4-alkyl phenol dithio ether is formed as follows:

' 0H 0H t J J 2 2801, --e

x a I OH- on on R s s a O Q U 4H0! T l V a 4 l When using 2 moles of 2,4-dialky1 phenol mixed with 2 moles of 4-alkyl phenol with sulfur dichloride the reaction proceeds in the same way but with the formation of bis-(2,4-dialkyl phenol)- dl-4-alkyl phenol trithio ether, a compound having four aryl groups, as follows: a

I 0H 0H 0H 0H S R O UT) O R; a a 1 and them to oils in this way in amounts sufll- When sulfur monochloride is substituted in place of the sulfur dichloride the aryl groups are bound together with two sulfur -atoms,--SS-, and n in the general formula above becomes 2'. These compounds possess similar properties to those inwhich a'single sulfur atom links the different aryl groups and are also valuable in our improved lubricating oils.

In preparing these new compounds it is convenient to dissolve the various reactants in an inert solvent such as carbon disulfide, carbon tetrachloride, petroleum naphtha, ethylene dichloride, chlorbenzene, chloroform or the like. Merely mixing together the various reactants in the desired molecular proportions will cause the reaction to be brought about. No catalyst is ordinarily necessary. The reaction vessel should be fitted with agitating means and means for removing the HCl liberated. Towards the end of the reaction when the evolution of HCl has slowed considerably the preparation may be completed by heating the reaction mass to 50-60" C. for a few minutes to expel most of the remaining HCl. The product may then be washed with a dilute alkaline solution to remove traces of the acid. In

the event that the material tends to emulsify during the washing step the addition of a small amount of butanol will help prevent emulsification. After washing the excess solvent may be.

by evaporation under salt with a desired metal salt such as, for ex-.

ample ZnClz, SnClz, A1013, etc. Metal salts of these compounds may also be prepared by reacting the compounds'just described. withappropriate molecular amounts of finely powdered metallic aluminum, metallic magnesium turnings calcium metal, etc. A small amount of mercur chloride may be added to start the reaction. The

reaction mixture may be gently heated on a steam bath at first but may require cooling later becaus of the exothermic character of the reaction Metal salts may also .be preparedby heating the compounds described with an alcoholate of a lower boiling alcohol, sodium methylate or aluminum butylate, for example, under conditions such that the lower alcohol is driven off.

The preparation .of the bis-(2)4-diamyl phenol)-4.-amyl phenol dithio ether will now be described. In this preparation 2,4-diamyl phenol is reacted with 4-amyl phenol and sulfur dichloride. As will be apparent we may. use other 2,4-dialkyl phenols with other 4-alky1 phenols in the preparation of these new compounds. The various alkyl groups R, R1 and R2 in the general formula above may be all the same or may be all different.

In this way it is possible to control the viscosity and oil solubility of the resulting compound. For ood oil solubility compounds employed should have at least one, preferably: more, alkyl groups .of from 4 to 14 carbon atoms.

01 the various 2,4-dialkyl-phenols which may be employed by us may be mentioned 2,4-diamyl phenol, 4-tertiary butyl ,orthocresol, 2-dodecyl- 4-tertiary amyl phenol, 2,4-di-tertiary butyl phenol, 2-buty1-4-isopropyl phenol, 2-butyl-4-amyl phenol, 2-isopropyl-4-octyl phenol, etc. As 4-alkyl phenols we may use those such as p-cresol, 4-isobutyl phenol, l-tertiary amyl phenol, 4-ethyl hexyl phenol, 4-octyl phenol, andthe like. As

' will appear from what has been said before with one. or two the relative amounts of the 2,4-diallwl phenol and 4-alkyl phenol can vary considerably depending upon thetypeof product desired. Ordinarily two molecular proportions of the 2,4--dialkyl phenol preferred.

' Example 164 parts by weight of p-tertiary amyl phenol and 468 parts by weight of 2,4-di-p-tertiary amyl phenol were dissolved in 260 parts by weight of benzol. 205 parts by weight of sulfur dichloride was then added to the solution with stirring, the

temperature being maintained below 40 0. As

7 soon as all the sulfur dichloride had'been added the mixture was warmed to 50-60 C. for 10 minutes to complete the reaction and expel most of the HCl. The reaction mixture was then washed with warm dilute sodium carbonate solution to remove dissolved hydrogen chloride.

The washed reaction product was then heated under reduced pressure to remove the benzol. Bis-(2,4-diamyl phenol) -4-amy1 phenol .dithio ether was obtained as a brown viscous product.

'. The barium salt of this product was obtainedby dissolving 60 part by weight thereof in 80 parts by weight of aromatic petroleum naphtha and 40 parts by weight of 95% alcohol. 41 parts -by' weight of finely ground Ba(OI-I)2.8H:O was added and the mixture heated and solvents and water boiled ofl. More naphtha was added from.

time to'time to replace that lost by evaporation. When the temperature has "reached 125-135 C.

the neutralization was substantially complete and all of the water had been expelled. The solution was then diluted with naphtha and after cooling filtered from traces ofinorganic bariumalts. The solvent was thenremoved by evaporation under reduced pressure. The product was a stiff viscous dark-colored liquid, easily oluble in light paraflin base lubricating oil. v

If desired lubricating oil may be added to the product before all of the solvent has been removed by evaporation. This step facilitates blending of the oil with the additive and enables us tq. obtain a product containing 50-80% or more, of the additive suitable for sale and dis-- tribution to the trade for blending purposes.

or the various bis-(2,4-dialkyl phenol) -4-alkyl phenol sulfides which may be employed by us we prefer to use the alkaline earth metal salts and particularly those salts in which the alkyl groups are of from 4 to 14 carbon atoms in length. These compounds are so very eflective that it is possible to improve lubricating oils to a great extent by the use of very small amounts of the compound. In lubricating oils intended for ordinary purposes where high temperatures occur only occasionally, from 0.1-.08% of the bis- (2,4-

dialkyl phenol) 4-alky l phenol sulfide is sub} ficient. In an oil intended for heavy duty service it is generally advisable to Ease a little more, as for example 0.54% in theoifi The effectiveness of the bis-(2,4-dialkyl phenol) -4-alkyl phenol sulfides in lubricating oils as corrosion inhibitors, detergents and anti-oxidants is demonstrated by the following results obtained by subjecting a S. A. E. solvent refined Pennsylvania oil containing 0.5% by weight of the barium 'salt of bis-(2,4-diamyl phenoD-4- amyl phenol dithio ether to the standard Underwood oxidation test. A sample of oil containing 0.5% of the barium salt of bis-(2,4-diamyl phenol' -di-'4-amyl phenol trithio ether and a, control sample containing no additive were also tested moles of the 4-alkyl phenol is L l l- I at the same time. The test consisted in heating 1500 cc. of the oil at 325 C. and continuously spraying a portion of the hot oil against a 3" x 10" freshly sanded copper 'baille and two -5 freshly sanded bearings to be tested for corrosion for 5 hours while permitting free circulation of air during the heating period. Samples of the oxidized oil were then examined for A. P. I.

gravity. neutralization number and the bearings 10 were examined for weight loss due to the effects The neutralization number indiof corrosion. cates the fomiationof acidsresulting from oxidation of the oil. The A. P. I. gravity also indicates the decomposition in the oil during the test, 15 the lower values indicating a greater degree of decomposition. Results wereas follows:

Underwood oxidation test The results of these tests clearly ShOW the antioxidant and anti-corrosion properties of oils treated with our new-bis-(2,4-dialkyl phenol) -4'- alkyl phenol sulfides.

.What we claim is: g 1. A lubricating oil composition containing lubricating oil and small amounts of a compound having the general formula in which R, R1 and R2 are alkyl radicals, n is a small whole number less than 3, m is a small whole number less than 3, Me is a metal, and x is the valence of Me.

bricatihg oil and 0.1-3.0% of a compound having the general formula in which R, R1 and a: are sum radicals, at least one of which has from 4 to 14 carbon atoms, n is a small whole number less than 3, m is a small whole number less than 3, Me is a metal, andxis' the valence of Me.- 7 3. A lubricating oil composition containing inbricating oil and small amounts of acompound having the general formula 2. A lubricating oil composition containing luin which 3,81 andRsare alky l radicals, nisa small whole number less than 3, Me is a metal, and X is the valence of Me.

4. A lubricating oil composition containing lubricating oil and small amounts of a compound having the general formula t I ,t

I t A A in which R, R1 and Rs are alkyl radicals, Me is a metal,-and x is the valence of Me.

6. A lubricating oil composition containing lubricating oil and (Ll-3.0% of a compound having the general Iormula ,1 R1, LQIQF in which R, R1 and R: are alkyl radicals, at least one oi which has from 4 to 14 carbon atoms, n is a small whole number less than 3, m is a small whole number less than 3, Me is an alkaline earth metal, and x is the valence of Me.

7. A lubricating oil composition containing lubricating oil and 0.1-3.0% 01 a compound having the general formula t I is IA in which R, R1 and R: are alkyl radicals, at least one of which has from 4 to 14 carbon atoms, n is a small whole number less than 3, andm is a small whole number less than 3.

ELMER W. COOK. WILLIAM D. THOMAS, JR.