US2352669A - Lubricating oil composition - Google Patents

Description

Patented July 4, 1944 LUBB'ICATING OIL COMPOSITION Paul B. Van Ess, Berkeley, and Ellis 8. White, Albany, Calif asslgnors to Shell Developme t Francisco mpany. San of Delaware No Drawing.

9 Claims.

. This application is a continuation-in-part of our, application Serial No. 376,330, flied January This inventionrelates to compounded'lubricating oils containing added ingredients which improve their properties in one or more important respects. It also deals with the addition of oil-soluble addition ,agents to compounded mineral oils to produce lubricating oils of improved anti-wear properties for internal combus- Calif., a corporat in Application December 26, 1941, Serial No. 424,544

' rosion inhibitors. extreme pressure compounds,

tion engines.- More particularly, it deals with the addition to lubricating oils of certain oilsoluble allophanates, which compounds have the property of modifying or reducing the hardness of carbon formed on pistons, and of preventing the baking of carbon, in piston grooves to the point of hardness and thus preventing the sticking of piston rings when running internal combustion engines for long periods of time.

It is known that in modern internal combustion engines such as aviation gasoline engines, due to their high power output and their relatively high operating temperatures,- or high speed Diesel engines due ,to incomplete combustion of the fuel, piston rings have a tendency to become stuck in the grooves and the pistons ten'd to become worn. m

The carbon deposited in internal combustion engines may be considered of two kinds, dependt ing on the type of oil High-viscosity index mineral oil tends to form hard carbon which may cause severescratching of parts of thepiston,

particularly top lands as well as piston rings,

etc.; while low-viscosity index oils in general form a softer carbon which does not scratch or scuff so badly. The presence of detergents in lubricating oils usually increases the tendency to scratch. Thus it is known that lubricating oils containing about 25% to 5% of oil-soluble detergents, such as the salts of polyvalent metals. or of organic amines,.with detergent-forming- ,acids, may cause damage to the top lands of pistons due toscumng.- Detergent-forming acids are, for example. naphthenic, aromatic car- .boxylic, .hydroxy aromatic carboxylic, ,paraflln and softening hard carbon, so that well-refined lubricating oils containing oil-soluble detergents which heretofore caused too much scumng can be used successfully, by adding small amounts of these allophanates; Oils so compounded have the valuable combination of properties of keeping the piston clean, retarding or preventing ringsticklng. positively reducing wear, and overcoming and preventing piston scufllng and scratching. If desired, oxidation inhibitors, coretc., may be added further to improve the desirable properties of the compounded oils containing the above combination of addition agents.

In stating that the allophanates modify the carbon formation on the pisto we mean that th stead of the usual hard, tough, adhesive deposits, we find that the carbon formed in the presence of the allophanates is a soft, velvety, non-adherent deposit which is almost oilyin character. Such deposits are so non-adherent they may be removed by wiping with the finger or a soft cloth, leaving a clean metal surface. No explanation can be offered for the above-observedphenomenon. According to this invention, allophanates which are added to lubricating oils containing a suflicient amount of a detergent normally to cause scratching or scuffing of'the pistons, for example,

. in Caterpillar Diesel engines, possess the following formula:

X-Bl

n Cx Rs In this formula X represents oxygen or sulfur; R2 and Rs are hydrogen or hydrocarbon radicals, preferably hydrogen; R1 is a saturated alicyclic radical having at least 12 carbon atoms.

'I'he hydrocarbon radicals R2 and Rs may contain preferably not more than one polar neutral or basic substltuent. Suitable substituents are. for example, halogen, -CN, OH, -OR','

Normally the alicyclic radical R1 is'sufllcient to insure the necessary oil-solubility. 1

v Preferred R1 radicals are those having at least two aliphatic rings, which may be condensed, and each portion having at least one branched alkyl radical. Such bi-alicyclic radicals may be obtained, for example, by hydrogenation of suitable naphthalene derivatives, as for example, a secondary or tertiary alkyl naphtholjto produce the corresponding alkyl decalols; or by suitably condensing aliphatic ketones to produce unsaturated bicyclic ketones which may then be hydrogenated to the corresponding alcohols, closely resembling the above decalols.

The amounts of our allophanates to be added to the hydrocarbon oils will vary with the type of improvement to be achieved and with the severity of the hard carbon normally formed by the 'oil. In general, the amountsrequired vary from .1% to 10%, and preferably from .5% to 5%. One group of detergents which is extremely effective in preventing ringstickin'gis known to comprise the salts of polyvalent metals with organic sulfonic acids, preferably the so-called oil-soluble petroleum sulfonic acids, also known as mahogany acids. Polyvalent metals suitable for this purpose are, particularly, Mg. Ca, Sr, Ba, Zn, Cd, Al, Sn, Pb, Bi, Cr, Mn, Co, Ni. However, these sulfonate detergents unfor unately cause unusually-severe sending and scr hing of the pistons. We have found that our allophanates are, therefore, particularly useful in combination with these sulfonates in that. this combination takes full advantage of the highly desirable detergent property of the sulfonate without allowing the disadvantages to make themselves felt.

Qther types of inhibitors may be. added, such as corrosion inhibitors. which are not anti-oxidants. or extreme pressure compounds which may contain radicals comprising elements of thegroup' consisting of S, P, or C1, provided these elements are attached in such a manner that they do not readily liberate corrosive compounds such as free sulfur,'chlorine,- or phosphoric acid, under conditions'of lubrication to which crankcase oils are usually exp'osed.- Also, mixtures of differentinhibitors are often very useful.

In accordance with the known fact that highviscosityindex oils cause more sending of pistons than low-viscosity oils, the combination of detergentsand' allophanates is'particularly useful in oils of relatively high viscosity, e. g., oils having 50 viscosity index or higher.

The followingexamples further illustrate the invention:

Example I An S. A. E. 30 lubricating oil having a vs'cosity index of 55, containing 2.25% of calcium petro-. leum sulfonate (produced by converting a commercial mahogany soap to the. I calcium salt),

0.25% phenyl alpha naphthylamine and 1.0% of an allophanate of a Cu; saturated .bicyclicalcohol The presence of oxidation inhibitors in addition to detergents and allophanates is desirable not only to protect hese additionlagents as well as the oil from rapid destruction by ox dation,

but also to prevent corrosion which may be caused by the detergent. l

For our purposes, the oxidation inhibitorsmay roughly be divided .into two groups: the phenolic type and the aryl amine type. Of these two. we

have found that the latter are in general more useful. Especially valuable are those am nes which eontain'at least one aromatic nucleus havfing two or more condensed aromatic rings. Thus,-

preferred anti-oxidants are, for example, the naphthylamines: primary, secondary, or tertiary alkyl, aryL-or aralkyl radicals, are'attach'ed'to an aromatic nucleus or preferably to the nitrogen atom, or both, such as phenyl alpha or beta naphthylamine, tetraline naphthylamine, alpha alpha,- alpha beta.or beta beta di-naphthylamines, various phenanthryl, anthryl, orp cyl naphthylamines, xenyl; naphthylamines, benzyl phenyl naphthylamines, -di-phenyl naphthylamines, phenyl xenyl naphthylamines, di-xenyl naphthylamines; also, various phenanthryl. anthryl,-or picyl phenyl amines, etc.

If desired, however,- other oxidation inhibitors We claim as our invention: Y 5

may be used as well. such as alkyl phenyl amines;

di-phenyl amines: or alkyl phenols, preferably containing at. least two alkyl radicals in2, 4, or '6 positions-to the OH radicahat least two alkyl radicals being linked to "the'aromatc' nucleus through a tertiary carbon atom; or alpha or beta naphthols, alkylated naphthols, p'henols, or .naphthols containing ether,thio ether, etc., linkages, polyhydric' alkyl benzenes or naphthalenes, such as alkylated catechol, etc. Suitable amounts of oxidation inhibitors usually vary between about .01%to1%. f 7

(produced by the condensation. of acetone and hydrogenation) was' subjected to a'126-hour test inv a Caterpillar test engine operated at 850 R. P. M. and at v16.! BrH. P. At the end of the run, the piston rings were free, ,the piston was clean, and the top land was free of hard carbon the metal was "not scufied. The amount of carbon deposit at the bottom of the top ring groove was small.

Example 11 An S. A. E. 30 lubricating oil containing 9% of rapeseed mlld voltol as a detergent, 0.1% n-butvl arsine disulflde as acorrosion inhibitorand 0.75% of Cm'saturated cyclo-alkyl allophanateas carbon modifier was subjected to-a 36-hour test in .a Chevrolet test engine under severe operating conditions (3150 R.'P. MJ. .At the end of the test the engine parts were free from lacquer and carbon deposits. a

' 1. An improved lubricant comprising a mineral lubricating oil having dissolved therein a small amount each of an oil-soluble detergent normally,

tending to .promote scratching or scufling of pistons and an oil-soluble allophanate selected from the group cons sting of allophanates of .alicarbocyclic alcohols and thio-aicohols. having at least 12 carbon atoms.

- 2. An improved lubricant comprising mineral lubricating oil having dissolved therein a relatively small amount each of an oil-soluble detergent normally tending to promote scratching or scufling of pistons. an amine anti-oxidant, and oil-soluble allophanate selected from the group consisting of allophanates of alicarbocyclic alcohols and thio-alcohols, having at least 12 carbonatoms. v 3.,An improved lubricanocomprising a mineral lubricating oil having dissolved there n 25% to 5% of an oil soluble detergent normally tending to promote scratching or scufling of-pistons and .1% to 10% of an oil-soluble allophanate'selected from the group consisting of allophanates of alicarbocyclic alcohols and-thin-alcohols,-having at least 12 carbon atoms.

4. An improved lubricant comprising a mineral lubricating oil having dissolved therein 25% to Y 16.5% of an oil-soluble detergent-normally 'tendg promote scratching or scufling of pistons and :rom .5% to 5% of an oil-soluble allophanate seected from the group consisting of allophanates if alicarbocyclic alcohols and thici-alcohols, havng at least 12 carbon atoms.

'5. An improved lubricant comprising a minaral lubricating oil having dissolved therein 25% to 5% of an oil-soluble detergent normally tending to promote scratching or sending of pistons, .1% to 1% of an amineanti-oxidant, and .1% to of an oil-soluble allophanate selected from the group consisting of allophanates of alicarbocyclic alcohols and thio-alcohols, having at least 12 carbon atoms.

6. An improved lubricant comprising a mineral lubricating oil having dissolved therein .25% to 5% of a polyvalent metal salt of petroleum sulfonate, and to 10% phanate selected from the allophanates of alicarbocyclic alcohols and thioalcohols having at least 12 carbon atoms.

'7. An improved lubricant comprising a mineral lubricating oil having dissolved therein to 5% calcium petroleum sulfonate, .1% to 1% phenyl alpha naphthylamine, and .1% to 10% of a branched-chain alkyl decalol allophanate.

8. The combosition of claim 7 wherein said decalol has 18 carbon atoms.

9. The composition of claim 7 in which the viscos-itv index of the mineral lubricating oil is above 50.

PAUL R. VAN ESS. ELLIS R. WHITE.

of an oil-soluble allo- I group consisting of