US2463429A - Lubricant - Google Patents

Description

Patented Mar. 1, 1949 LUBRICANT Edward N. Roberts, Hammond, Ind., assimor to Standard Oil Company, Chicago, 111., a corporation of In No Drawing. Application December 30, 1944, Serial No. 570,762

8 Claims. (Cl. 252-323) This invention relates to improvements in lubricant compositions and more particularly to hydrocarbon oil compositions which are noncorrosive and resistant to oxidative deterioration. More particularly the present invention is directed to internal combustion engine lubricants which are resistant to the formation of gums, resinous and varnish-like materials and which are non-corrosive to metal surfaces, especially bearings of the hard metal alloy type.

Straight petroleum lubricants are effective within certain defined limits of engine operating conditions but when these limits are exceeded, such lubricants frequently fail to give the desired performance demanded of them. Since in modern engine design to give increased performance these limits are frequently exceeded, the use of straight mineral oils as lubricants produces undesirable conditions within the engine. Thus varnish and carbon formation is excessive and corrosion of improved hard metal alloy bearings of the cadmium-silver and copper-lead type is encountered. In order to overcome some of these deficiencies in the properties of hydrocarbon oils, certain types of additives have been added to lubricant compositions to impart thereto properties such as resistance to oxidative deterioration.

and corrosion inhibiting properties. Many of these additives are capable of imparting all of these desirable properties to lubricants under certain normal conditions but frequently such additives fail to afford the desired protection in one or more respects.

It has heretofore been found that certain reaction products of a. phosphorus sulfide and a hydrocarbon, particularly an olefin or an olefin polymer, when added in small amounts to a hydrocarbon oil such as a mineral oil in combination with small amounts of an organic sulfur compound or elemental sulfur, effectively inhibit the. formation of sludge and/or varnish-like deposits and inhibit the corrosion to metal surfaces, particularly to the bearings of the hard metal alloy type. The use of small amounts of an organic sulfur compound or elemental sulfur in combination with the neutralized reaction products of a phosphorus sulfide and a hydrocarbon in lubricants is the subject matter of United States Patent 2,316,090, issued to C. D. Kelsoand L. W. Mixon on April 6, 1943. While the organic sulfur compounds or elemental sulfur in combination with the neutralized reaction products of a phosphorus sulfide and a hydrocarbon are normally effective in inhibiting corrosion, under some conditions they frequently fail to afford the desired protection.

It is an object of the present invention to provide a combination of additives for oils, particularly hydrocarbon oils such as mineral oils, which will stabilize such oils against oxidative deterioration and which will render such oils non-corrosive. It is another object of the invention to provide lubricants for internal combustion engines which do not form carbonaceous deposits or resinous varnish-like materials on and about the valves, pistons and rings of such engines and which are not corrosive to metals, particularly to hard alloy bearing metals of the copper-lead and cadmium-silver type.

In accordance with the present invention the foregoing objects can be attained by adding to oils such as hydrocarbon oils, for example, mineral lubricating oils, small amounts of a polyhydroxy aromatic compound in combination with .a small amount of the neutralized reaction products of a phosphorus sulfide and a hydrocarbon. The polyhydroxy aromatic compound can be employed in amounts of from about 0.001% to about 2% and preferably from about 0.01% to about .5% and the neutralized" phosphorus sulfide-hydrocarbon reaction products can be employed in amounts within the range of from about 0.001% to about 10% and preferably from about 0.01% to about 3%. In addition the lubricant composition may contain from about 0.001% to about 5% of elemental sulfur or other organic sulfur compounds such as sulfurized mineral oil, sulfurized olefin polymers, sulfurized terpenes and the like.

It is also within the contemplation of this invention to provide the combination of addition agents, herein-described, in the form of a concentrate in a suitable oil base, the concentrate containing more than 2% of the polyhydroxy aromatic compound and more than 10% of the neutralized phosphorus sulfide-hydrocarbonreaction product. Such concentrates are used for blending with the hydrocarbon oil or other oils in the proportions desired for the particular conditions of use.

The polyhydroxy aromatic compounds or their partially etherified or esterifled derivatives employed in the herein-described invention are those having the general formula Ra-Ar-(OR'): in which R, represents hydrogen, alkyl or aryl substituents, Ar represents a monoor polycyclic aromatic nucleus such as, for example, benzene, naphthalene, anthracene, phenanthrene, etc., R represents hydrogen, alkyl, aryl, alkanoyl or aroyl substituents at least one of which is hydrogen and :r is an integer greater than 1. The aromatic nucleus may contain, in addition to alkyl or .aryl substituents, groups such as nitro, aldehyde, keto, amino, alkoxy, carbox-y, and other radicals. Examples of specific compounds falling in the above defined class are: catechol, hexylcatechol, octylcatechol, dodecylcatechol, pyrogallol, capryl pyrogallol, 'resorcinol, hexyl resorcinol, hydroquinone, phloroglucinol, hy-

droxyquinone, dihydroxynaphthaquinone, dihy- 2o droxyanthraquinone, trihydroxyanthraquinone, peri-dihydroxy-napthalene, peri-dihydroxyanthracene, alkylated catechol, alkylated dihydroxynaphthaqulnones, alkylated dihydroxyanthraquinone, alkylated trihydroxyanthraquinone, alkylated perl-dihydroxynaphthalene, alkylated peri-dihydroxyanthracene, 2,4-dihydroxybenzaldehyde; 2,3-dihydroxybenzaidehyde; 2-hydroxy- 3-methoxybenzaldehyde; benzaldehyde; 2,3-dihydroxybenzophenone; 2,4- dihydroxybenzophenone; 2-hydroxy-3-methoxybenzophenone; 2-hydroxy-4-methoxybenzophenone; 2,2'-dihydroxybenzophenone; 2,3-dihydroxyacetophenone; 2,5-dihydroxyacetophenone; 3,4-dihydroxyacetophenone; the monoalkyl and aryl ethers of these dihydroxyacetophenones; 3,4-dihydroxydiphenyl; dihydroxynaphthalenes and dihydoxyanthracene in which the two hydroxy groups are in adjacent positions; monoand dialkyl (such as methyl, ethyl, propyl, isopropyl, butyl and amyl) esters of 3,4-dihydroxyphthalic acid and their monoallqrl and aryl ethers; alkyl (such as methyl, ethyl, propyl, butyl, amyl and cetyl) esters of 2,4-dihydroxybenzoic acid and their 4-alkyl ether derivatives, alkyl (such as propyl, isopropyl, butyl, isobutyl, amyl, octyl. nonyl, decyl, dodecyl, lauryl and cetyl) esters of gallic acid and digallic acid and their alkyl ethers; monomethyl and monoethyl ethers of capryl pyrogallol and alkylated pyrogallol.

The specific activity of the various polyhy'droxy aromatic compounds varies to some extent, all of them, however, being effective to some degree as corrosion inhibitors. It is therefore not to be implied that all the polyhydroxy aromatic compounds of the classes herein-described are equivalents.

As aforesaid, one of the components of the improved lubricant is the neutralized reaction product of a hydrocarbon and a phosphorus sulfide such as P283, P483, P487, or other phosphorus sulfides and preferably phosphorus pentasulfide,

P2S5. The hydrocarbon constituent of this reao tion is preferably a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight-mono-oleflnic hydrocarbons or isomono-oleflnic hydrocarbons such as propylenes, butylenes, and amylenes or the copolymers obtained by the polymerization of hydrocarbon mixtures containing isomono-olefins and monoolefins of less than 6 carbon atoms. The polymers may be obtained by the polymerization of these olefins or mixtures of oleflns in the presence of a catalyst such as sulfuric acid, phosphoric acid,

z-hydroxy-i-methoxy-v boron fluoride, aluminum chloride or other similar halide catalysts of the Friedel-Crafts type.

The polymers employed are preferably monoolefln polymers or mixtures of mono-olefin polymers and isomono-oiefln polymers having molecular weights ranging from about 150 to about 50,000 or more, and preferably from about 500 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid phase of a hydrocarbon mixture containing monoolefms and isomono-oleflns such as butylene and isobutylene at a temperature of from about -80 F. to about 100 F. in the presence of a metal halide catalyst of'the Friedel-Crafts type such as, for example, boron fluoride, aluminum chloride and the like. In the preperation of these polymers we may employ, for example, a hydrocarbon mixture containing isobutylene, butylenes and butanes recovered from petroleum gases especlally those gases produced in the cracking of petroleum oils in the manufacture of gasoline.

A suitable polymer for the reaction with phosphorus sulfide is the product obtained by polymerizing in the liquid phase a hydrocarbon mix- 5 ture containing butylenes and isobutylenes to- 5 temperature within the reactor so that gether with butanes and some C: and Ca hydrocarbons at a temperature between about 0 F. and 30 F. in the presence of aluminum chloride. A suitable method for carrying out the polymerization is to introduce the aluminum chloride into the reactor and introduce the hydrocarbon mixture cooled to a temperature of about 0 F. into the bottom of the reactor and pass it upwardly through the catalyst layer while regulating the the polymer product leaving the top of the reactor is at a temperature of about 30 F. After separating the polymer from the catalyst sludge and unreacted hydrocarbons, the polymer is fractionated to ob- 40 tain a fraction of the desired viscosity such as,

for example, from about seconds to about 2000 seconds Saybolt Universal at 210 F.

Another suitable polymer is that obtained by polymerizing in the liquid phase a hydrocarbon mixture comprising substantially Cs hydrocarbons in the presence of an aluminum chloride-complex catalyst. The catalyst is preferably prepared by heating aluminum chloride with isooctane. The hydrocarbon mixture is introduced into the bottom of the reactor and passed upwardly through the catalyst layer, while a temperature of from about 50 F. to about 110 F. is maintained in the reactor. The propane and other saturated gases pass through the catalyst, while the propylene is polymerized under these conditions. The propylene polymer can be fractionated to any desired molecular weight, preferably from about 500 to about 1000 or higher.

Other suitable polymers are those obtained by polymerizing a hydrocarbon mixture containing about 10% to about 25% isobutylene at a temperature of from about 0F. to about F. and preferably 0. F. to about 32 F. in the presence of boron fluoride. After the polymerization of the isobutylene together with a relatively minor amount of the normal oleflns present, the reaction mass is neutralized, washed'free of acidic substances and the unreacted hydrocarbons subsequently separated from the polymers by distillation. The polymer mixture 50 obtained depending upon the temperature of reaction, varies in consistency from a light liquid to viscous, oily material and contains polymers having molecular weights ranging from about 100 to about 2000 or higher. The polymers so obtained may be used as such, or

the polymer may be fractionated under reduced pressure into fractions of increasing molecular weights, and suitable fractions obtained reacted with the phosphorus sulfide to obtain the desired reaction products. The bottoms resulting from the fractionationof the polymer which may have Saybolt Universal viscosities at 210 1". ranging from about 50 seconds to about 10,000 seconds, are well suited for the purpose of the present invention.

Essentially paraillnie hydrocarbons such as bright stock residuums, lubricating oil distillates, petrolatums, or paraflln waxes may be used. There can also be employed the condensation products of any of the foregoing hydrocarbons, usually through first halogenating the hydrocarbons, with aromatic hydrocarbons in the presence of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride and the like.

Examples of high molecular weight oleflnic hydrocarbons which can be employed as reactants are cetene (Cm) cerotene (C20) melene (Cap) and mixed high molecular weight alkenes obtained by cracking petroleum oils.

Other preferred olefins suitable for the preparation of the herein-described phosphorus sulfide reaction products are olefins having at least 20 carbon atoms in the molecule of which from about 13 carbons atoms to about 18 carbons atoms, and preferably atleast carbons atoms, are in a long chain. Such olefins can be obtained by the dehydrogenation of paraffins, such as by the cracking of parfiln waxes, or by the dehalogenation of alkyl halides, preferably long chain alkyl halides, particularly halogenated parafiin waxes.

The olefins obtained by dehalogenation of long chain alkyl halides. are preferably those obtained by dehydrohalogenation of monohalogenated waxes, such as, for example, those obtained by dehydrochlorination of monochloroparafiin wax. The alkyl halides are decomposed to yield olefins according to the reaction in which n is a' whole number, preferably 20 or more, and X is a halogen. It is preferred to employ paraifin waxes having at least about 20 carbon atoms per molecule, and melting points upwards from about 90 F. to about 140 F.

- To obtain the halogenated paraifin wax, for example, chlorinated parafiin wax. chlorine is introduced into the wax, maintained in a molten state, until the wax has a chlorine content of from about 8% to about 15%. The chlorinated wax product is a mixture of unchlorinated wax, monochlorowax and polychlorowax. This chlorinated product may be used as such, but it is advantageous to use the substantially monochlorowax fraction. The monochlorowax fraction can be segregated from the unchlorinated wax and the polychlorowax fractions by taking advantage of the differences in the melting points of the various fractions, since the melting point of the wax varies with the extent of chlorination, i. e. the melting point of the unchlorinated wax is greater than that of the monochlorowax, and the melting point of the latter is greater than that of the polychlorowax. Thus, the monochloroparatfin wax can be separated from the unchlorinated and the polychlcroparafiin wax fractions by means such as sweating, fractional distillation, solvent extraction, solvent precipitation, and fractional crystallization.

The high molecular weight olefins are obtained by removing the halogen as hydrogen halide from the halogenated parafiin wax. For example, the corresponding olefin is obtained from the monochloroparailln wax by removing the chlorine from the latter as hydrogen chloride. The monochlorowax can be dehydrochlorinated by heating to a temperature of from abput200 F. to about 600 1". in the presence of a dehydrochlorinatipg agent such as an alkali metal hydroxide or earth metal hydroxide or oxide. Other alkaline inorganic or organic materials can also be used. The chlorine can also be removed from the chlorowax by heating the same for a prolonged period in the absence of any dehydrochiorinating agent. After the dehydrohalogenation has been completed the olefin so obtained can be further purified by removing the dehydrohalogenating agent by means of filtration or by other suitable means.

As a starting material there can be used the polymer or synthetic lubricating oil obtained by polymerizing unsaturated hydrocarbons resulting from the vapor phase cracking of paraflln waxes in the presence of aluminum chloride which is fully described in United States Patents Nos. 1,995,260, 1,970,002 and 2,091,398. Still another type of olefin polymerwhich maybe employed is the polymer resulting from the treatment of vapor phase cracked gasoline and/or gasoline fractions with sulfuric acidor solid adsorbents such as fullers earth whereby unsaturated polymerized hydrocarbons are removed. Also contemplated within the scope of this invention is the treatment with phosphorus sulfide of the polymers resulting from the voltolization of hydrocarbons as described, for example, in United States Patents Nos. 2,197,768 and 2,191,787.

Also contemplated within the scope of the present invention are the reaction products of a phosphorus sulfide with an aromatic hydrocarbon such as, for example, benzene, naphthalene, toluene, xylene, diphenyl and the like, or with an alkylated aromatic hydrocarbon such as, for example, benzene having an alkyl substituent having at least four carbon atoms and preferably at least eight carbon atoms such as a long chain paraifin wax.

The phosphorus sulfide-hydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide, for example P285, with the hydrocarbon at a temperature of from about 200 F. to about 500 F. and preferably from about 200 F. to about 400 F., using from about 1% to about 50% and preferably from about 5% to about 25% of the phosphorus sulfide in the reaction. It is advantageous to maintain a non-oxidizing atmosphere such as, for example, an atmosphere of nitrogen above the reaction mixture. Usually it is preferable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary; however, an excess amount of phosphorus sulfide can be used and separated from the product by'filtration or by dilution with a solvent such as hexane, filtering and subsequently removing the solvent by suitable means such as by distillation. If desired the reaction product can be further treated with an agent having an active hydrogen atom such as steam at an elevated temperature of from about F. to about 600 1".

The phosphorus sulfide-hydrocarbon reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The phosphorus sulfide-hydrocarbon reaction product when neutralized with a basic reagent an alkaiine containing a metal constituent is characterized by the presence or retention of the metal constituent. of the basic reagent. Other metal constituents such as a heavy metal constituent can be introduced into the neutralized product by reacting the same with a salt of the desired heavy metal.

The term neutralized phosphorus sulfide-hydrocarbon reaction product" as used herein means a phosphorus sulfide-hydrocarbon reaction product having at least about 1% of its titratable acidity neutralized by the reaction with a basic reagent and includes the neutralized phosphorus sulfide-hydrocarbon reaction products containing a metal constituent resulting from said neutralization or resulting from the reaction of a heavy metal salt with the phosphorus sulfide-hydrocarbon reaction product treated with a basic reagent.

mg 3 x 1 centimeter strips of lead and copper-lead alloy in 250 cc. of the lubricant which is maintained at a temperature of 280 F. and stirred at 1300 R. P. M. To accelerate the oxidation small amounts of naphthenic acid are added to the lubricant oil being tested. In one set oftests 0.10% naphthenic acidwas employed while in another series 0.05% of the naphthenic acid was used. Periodically the test strips were removed from the lubricant oil bath and the loss in weight (expressed in mg.) was determined. In the table below the control lubricant ofl was a solvent refined M. C. SAE 30 oil containing 1.5% of a EOE neutralized PaSs-isobutylene polymer reaction product, and 0.16% sulfur added as sulfurized hydrocarbons. The catalyst A in the table denotes 0.1% naphthenic acid and the catalyst B was 0.05% naphthenic acid.

Hours Catalyst Control Oil. A 100 104 Control+0.50% caprylpyrogallol A 8 30 Control Oil B 42 53 scandals? hexylcatechol- B 0. 0 0. 5 1. 0 C0ntr0l+0.5 hexyicatechol. B 0.6 0.5 0.5 Oontrol+0.l% hexylcatechol i B 0. 5 l. 0 l. 0 Control-+0.25 2,4-dihydi'oxybenzaldehy B 0.8 0.8 0.8 Controi+0.05 2,4-dil1ydroxybenzaldehyde. B 0.0 0.0 0.0 Control+0.0i ,2,4-dil1ydrox benzaldehyde....- B 7 l3 Control+0. caprylpyrog o1 B 0.2 2 4.5

phorus sulfide-hydrocarbon reaction productris' carried out preferably in a non-oxidizing. at,- v

mosphere by contacting the acidic reaction product either as such or dissolved in a suitablegsolvent such as naphtha with a solution of the basic re agent, for example, potassium hydroxide o'r hydroxide dissolved in alcohol.- AsIanialterna tive method, the reaction product treated :plied -to 1lubricating oils, I conteniplate'the use with solid alkaline compounds such,;as1fKQI-I,i=

NoOH, NazCOs, KaCOa,

CaO, I was. and the J1me i at an elevated temperature 1of.fror'n a ut j F. to about 600 F. -As was aforesai E-WheB" h phosphorus sulfide-hydrocarbon rejaction product metal constituent, the. neutralizedreaction product is characterized'fby the presence the metal constituent of the basicreagent.- Neutralized. re'

action products containing 'a heavy metal constituent such aszfor example, tin, titanium, alumlnum, chromium-cobalt, zinc, iron, the like, by reacting a salt of thedesired can be obtained '65 is neutralized 'witha basic reagent containing'a' present -.-inytl1e lubrica rit ,fflcations as, come The above data clearly show the marked corrosion inhibiting property of polyhydroxy aromatic compounds of the type herein-described.

In addition to'the additives such as 'oil solubleorganic amines (for example primary', s eccndary or. tertiary aliphatic amines, aromatic amines, or with .nitrogenatoms in the aryl ring), pour point depressors, antioxidants, metal deactivators, anti 'rustagents, corrosion inhibitors, V. I. improvers,

extreme pressure agents, and the like may be A composition. While I; have, described my invention as apof thejcombination oftheherein-described additiveS :in products other'than lubricating oils,,such fuel oils, insulating oils, waxes,

T vegetable oils. and the like.

'While I have described my invention by reference tip-specific preferred embodiments thereof,

thejinvention is not to be considered as limited thereto but includes within its scope such modiwithin the spirit of the append-. edclaims. j f I q 1. A hydrocarbon oilbcontainingin combina- -tion therewitli fromyabout 0.001% to 'abwt'az' .of a polyhydr aromatic compound ofthe group consisting'ofi a polyhydrox larornatic alcohol and a pdlyhydro aromatic aldehyde and abo 'it heavy metal withlthe phosphorus si lfldt-i l,Vdro- 5 carbon reactioll- I? when the neutralization is a, a s chxas-nm. roduct h ving excess basicity may be'ont m q; I 1

The effectiveness of the miy mm mae i compounds in inhibiting the corrosivejfactid lubricant compositions containinga small of a neutralized phosphorus sulilde hy with a'basic reagent It that j .5. Acompositioti 0.001 7o to abo t 10% of a neutralized phosphorus-e and .su1f .-Q taining reaction product off'a phosphorus 'sulfldecand an olefin polymer. 7

A; as described 'ln-claiml in P which tli e.;.-olefin1polymergis a polybutyleng 3. AQcompositions-as' described "in 11in i j 1 i -mmwlmi 9 '4. A 'coni csitionas described in claim' 1 1:

which the -ipolyhydroiy aromatic alcoholjis s as described in claim 1- is foregoing additives, other tertiary aryl amines 2,488,429 9 which the polyhydroxy aromatic alcohol is hexylcatechol.

6. A composition as described in claim 1 in which the polyhydroxy aromatic alcohol is capryl pyrogallol. I

7. A composition as described in claim- 1 in which the polyhydrox aromatic aldehyde is 2,4-dihydroxy benzaldehyde.

8. A mineral lubricating oil containing in combination therewith from about 0.001% to about 2% Of a polyhydroxy aromatic compound of the group consisting of a polyhydroxy aromatic alcohol and a polyhydroxy aromatic aldehyde and from about 0.001% to about 10% of a phospho-- rus-and sulfur-containing neutralized reaction product of a phosphorus sulfide and an olefin polymer.

EDWARD N. ROBERTS,

10 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number