US 3296137 A
Description (OCR text may contain errors)
United f States Patent Qfifice 3,296,137 Patented Jan. 3, 1967 No Drawing. FiledyMay 13, 1965, Ser. No. 455,655 7 Claims. (Cl. 252--48.2)
This: application relates to lubricating compositions and in :a more particular sense it relates to mineral lubricating compositions having improved lubricating "properties Lubricating compositions, especially those useful in automotive engines, gears, and transmissions, must withstand: prolonged use under severe service conditions and must; have a host of desirable lubricating properties. Among such properties is the ability of the lubricating composition to prevent wear of the equipment which it lubricates and its ability to prevent corrosion of the metal parts of the equipment. Mineral lubricating oils tend to deteriorate in prolonged use and at high temperatures; The products of such degradation are corrosive to metal and the tendency of mineral lubricating compositions to, form such products necessitates frequent replacement .of used lubricating compositions in the equipment A great deal of effort has been devoted to the preparation :of lubricants which are effective to prevent wear of metal equipment and which are non-corrosive to metal. A common practice is to incorporate in the lubricating composition organic sulfur, compounds such as organic disulfides which impart anti-Wear properties to lubricants. A drawback of such compounds, however, is the tendency .of such sulfur compounds to form corrosive degradation products and to develop an offensive odor, especially when the lubricant is subjected to high temperature service conditions. These undesirable characteristics. impair the utility of organic sulfur compounds in lubricants;
Accordingly, it is a principal object of this invention to provide lubricants which have anti-corrosive properties and which do not tend to develop offensive odor.
It iswalso an object of this invention to provide lubricants useful in internal combustion engines.
It islalso an object of this invention to provide lubricants for automotive engines, gears, transmissions, etc.
These and other objects are attained by providing a lubricating composition comprising a major proportion of a lubricating oil and a minor proportion of a sulfide having the structural formula 1 wherein R is a hydrocarbon radical and R is selected from-theclass consisting of hydrogen and hydrocarbon radicals and x is an integer from 1 to 2.
The, sulfides conforming to the above formula may be conveniently referred to as aldehydo-hydrocarbon monoor: disulfides. The disulfides are especially useful in this isobutyl, sec-butyl, cyclohexyl, cyclopentyl, octyl, do-
decyl,1octadecyl, eicosyl, behenyl, triacontanyl, phenyl, naphthyl, phenethyl, octylphenyl, tolyl, xylyl, dioctadecylphenyl, triethylphenyl, alpha-methyl beta naphthyl, chlorophenyl, methoxy-phenyl, dibromophenyl, nitrophenyl, 8phenyl-octadecyl, 10-tolyl-dodecyl, S-chlorohexyl.
Sulfides having the following formula 1 R1 OGH-OS-S--OHO wherein R is as described previously are especially useful in the lubricating composition of this invention. The
term hydrocarbon radical is meant to describe a radical it. wherein R and R are as described previously. The sulf-urization may be accomplished by reacting the aldehyde with a sulfur halide such as sulfur monochloride (i.e., S Cl sulfur dichloride, sulfur monobromide or sulfur dibromide.
The reaction of an aldehyde with a sulfur halide may be effected simply by mixing the two reactants at the desired temperature which may range from -30 C. to about 250 C. or higher. The preferred reaction temperature is within the range of from about 10 C. to about C.
The reaction may be carried out in the presence of a diluent or solvent such as benzene, naphtha, hexane, carbon tetrachloride, chloroform, mineral oil, etc. The diluent solvent facilitates the control of the reaction temperature and a thorough mixing of the reactants.
The relative amounts of the aldehyde and the sulfur halide may vary within wide ranges. In most instances, the reaction involves two moles of the aldehyde and one mole of the sulfur halide and in other instances an excess of either one reactant may be used.
The preparation of the sulfides useful in the lubricating composition of this invention is illustrated by the following examples:
EXAMPLE 1 Isobutyraldehyde (1440 grams, 20 moles) is added in small increments to sulfur monochloride (1350 grams, 10 moles) at 5260 C. and under nitrogen atmosphere. The reaction is slightly exothermic. The reaction mixture is then heated to C./1l-13 mm. to distill off volatile components. The residue is filtered and the filtrate is the desired product having a sulfur content of 30.5% (theoretical sulfur content of 31.1%).
EXAMPLE 2 The procedure of Example 1 is repeated except that sulfur monochloride is replaced on a molar basis with sulfur dichloride. The product is a monosulfide.
The sulfides prepared by the procedure exemplified above are effective to impart anti-wear and anti-corrosive properties to lubricants, and they are especially desirable for use as lubricant additives because of their thermal and oxidative stability. They are further desirable because lubricants containing such sulfides do not tend to develop offensive odor which is typical of organic sul- 3 fur compounds present in lubricants subjected to prolonged use and high temperatures. These desirable properties are related directly to the structural composition of the sulfides of this invention and more particularly they are related directly to the presence of the aldehyde groups within the molecular structure of the sulfides.
The lubricating oils in which the sulfides are useful as additives may be of mineral, animal, vegetable, or synthetic origin. Ordinarily mineral lubricating oils are preferred because of their availability, general excellence, and low cost. For certain applications oils belonging to one of the other types may be preferred. For instance, synthetic polyester oils such as dioctyl adipate and di-2- ethyl-hexyl sebacate are often preferred as jet engine lubricants. Normally the preferred lubricating oils are fluid oils ranging in viscosity from about 400 SUS (Saybolt Universal seconds) at 100 F. to about 500 SUS at 210 F.
A small amount of the sulfide is usually efiective to impart the desirable properties to a lubricant. Such amount may be as low as 0.01% by weight of the final lubricant. The optimum concentration of the sulfide is usually Within the range of from about 0.05% to about 2% by weight of the lubricant. In some applications, such as in diesel engine lubricants, the sulfide may be present at a concentration as high as 5% or The present invention contemplates the use of other additives in the lubricant containing the sulfide additive. Such other additives include, for instance, detergents of the ash-containing type, viscosity improving agents, pour point depressing agents, anti-foam agents, extreme pressure agents, rust-inhibiting agents, oxidation-inhibiting agents, friction-improving agents, and corrosion-inhibiting agents.
The ash-containing detergents are exemplified by oilsoluble neutral and basic salts of alkali or alkaline earth metals with sulfonic acids, carboxylic acids, or organic phosphorus acids characterized by at least one direct carbon-to-phosphorus linkage such as those prepared 'by the treatment of an olefin polymer (e.g., polyisobutene having a molecular Weight of 1000) with a phosphorizing agent such as phosphorus trichloride, phosphorus heptasulfide, phosphorus pentasulfide, phosphorus trichloride and sulfur, White phosphorus and a sulfur halide, or phosphorothioic chloride. The most commonly used salts of such acids are those of sodium, potassium, lithium, calcium, magnesium, strontium, and barium.
The term basic salt is used to designate the metal salts wherein the metal is present in stoichiometrically larger amounts than the organic acid radical. The commonly employed methods for preparing the basic salts involves heating a mineral oil solution of an acid with a stoichiometric excess of a metal neutralizing agent such as the metal oxide, hydroxide, carbonate, bicarbonate, or sulfide at a temperature above 50 C. and filtering the resulting mass. The use of a promoter in the neutralization step to aid the incorporation of a large excess of metal likewise is known. Examples of compounds useful as the promoter include phenolic substances such as phenol, naphthol, alkylphenol, thiophenol, sulfurized alkylphenol, and condensation products of formaldehyde with a phenolic substance; alcohols such as methanol, 2 propanol, octyl alcohol, Cellosolve, carbitol, ethylene glycol, stearyl alcohol, and cyclohexyl alcohol; amines such as aniline, phenylenediamine, phenothiazine, phenylbeta-naphthylamine, and dodecylamine. A particularly effective method for preparing the basic salts comprises mixing an acid with an excess of a basic alkaline earth metal neutralizing agent, a phenolic promoter compound, and a small amount of water and carbonating the mixture at an elevated temperature such as 60 200 C.
Extreme pressure agents and corrosion-inhibiting and oxidation-inhibiting agents are exemplified by chlorinated aliphatic hydrocarbons such as chlorinated Wax; organic sulfides and polysulfides such as benzyl disulfide, bis-(chlorobenzyl)disulfide, dibutyl tetrasulfide, sulfurized sperm oil, sulfurized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, and sulfurized terpene; phosphosulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine or methyl oleate; phosphorus esters including principally dihydrocarbon and trihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentyl phenyl phosphite, dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthyl phosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecular weight 500)-substituted phenyl phosphite, diisobutyl-substituted phenyl phosphite; metal thiocarbamates such as zinc dioctyl-dithiocarbamate, and barium heptylphenyl dithiocarbamate; Group II metal phosphorodithioates such as zinc dicyclohexylphosphorodithioate, zinc dioctylphosphorodithioate, barium di(heptylphenyl)phosphorodithioate, cadmium dinonylphosphorodithioate, and zinc salt of a phosphorodithioic acid produced by the reaction of phosphorus pentasulfide with an equimolar mixture of isopropyl alcohol and n-hexyl alcohol.
The lubricating compositions may also contain metal detergent additives in amounts usually within the range of about 0.1% to about 20% by weight. In some applications such as in lubricating marine diesel engines the lubricating compositions may contain as much as 30% of a metal detergent additive. They may also contain extreme pressure addition agents, viscosity index improving agents, and pour point depressing agents, each in amounts within the range of from about 0.1% to about 10%.
The following examples are illustrative of the lubricating compositions of this invention (all percentages are by weight):
Example A SAE 20 mineral lubricating oil containing 0.5% of the disulfide of Example 1.
Example B SAE 30 mineral lubricating oil containing 0.1% of the monosulfide of Example 2.
Example C SAE 10W30 mineral lubricating oil containing 0.05% of bis(4-aldehydo-4-heptyl)disulfide and 0.1% of barium mahogany sulfonate.
Example D SAE mineral lubricating oil containing 0.75% of bis(9-aldehydo-9-heptadecyl)disulfide and 0.01% of phosphorus as barium didodecyl phosphorodithioate.
Example E SAE 30 mineral lubricating oil containing 1% of bis(1- aldehydo-l-phenyl-l-ethyl)disulfide and 0.5% of calcium dioctylphenate.
Example F SAE 20W-40 mineral lubricating oil containing 1.5% of bis(2-aldehydo-2-hexyl)monosulfide and 0.05 of 4, 4'-methylene bis(2,6-ditertiary butyl phenol).
The effectiveness of the sulfides of this invention as an additive in a lubricant to minimize its corrosiveness is shown by a Co-Ordination Research Council engine test. This test, which employs a single cylinder, spark ignition engine, involves running the engine under constant speed, constant air-fuel ratio and constant flow conditions for a total of 40 hours after a break-in period of 4.5 hours. The weight loss of the copper-lead bearings after completion of the test is an indication of the relative corrosiveness of the lubricant treated. The results are summarized in Table I below.
The. utility of the sulfides of this invention as an additive in lubricants intended for use in the crankcase of internal combustion engines is shown by a Co-Ordination Research Council engine test. In this test the lubri eating composition is used in the crankcase of a 4-stroke diesel: engine :having; a compression ratio of 15:1 operated.for 48O hours under the following conditions:
speed, .1000 r.p.m.; B.t.u. input per minute 2900-3000;
load, 20 brake horsepower; water jacket outlet temperaj ture1 175*180F. oil temperature,.140150 F. A
diesel. fuelz; having a sulfur content of 1% is used and the oil .iszichanged after every 120 hours of operation. Thcwilubrica'tion composition is evaluated according to (l) the piston cleanliness (rating scale of 100, 100
. being indicative of no deposit and 0 being indicative of 1 heavy deposit) and. (2) the amount of ring filling. A SAE 3-0 mineral base. lubricant containing 0.51% by weight of bis(.2 aldehydo 2 propyl)disulfide passes Q the test with1the following rating: piston cleanliness, 96.5;
What is claimed is: 1. A lubricating composition comprising a major prot portion of a lubricating oil and a minor proportion of a sulfide having the structural formula wherein R is a hydrocarbon radical and R is selected from the class consisting of hydrogen and hydrocarbon radicals and x is an integer from 1 to 2.
2. The lubricating composition of claim 1 wherein R and R are alkyl radicals.
3. The lubricating composition of claim 1 wherein R and R are lower alkyl radicals having up to about 8 carbon atoms.
4. The lubricating composition of claim 1 wherein R is a lower alkyl radical having up to about 8 carbon atoms and R is hydrogen.
5. A lubricating composition comprising a mineral lubricating oil and a minor proportion of a sulfide having the structural formula wherein R and R are lower alkyl radicals having up to about 8 carbon atoms.
6. A lubricating composition comprising a mineral lubricating oil and a minor proportion of a sulfide having the structural formula R1 R1 1 l 0CII SSCCHO H3 H3 wherein R is an alkyl radical having up to about 8 carbon atoms.
7. A lubricating composition comprising a mineral lubricating oil and a minor proportion of a sulfide having the structural formula References Cited by the Examiner UNITED STATES PATENTS 2,5 80,695 1/ 1952 Niederhauser 260601 DANIEL E. WYMAN, Primary Examiner.
L. G. XIARHOS, Assistcm't Examiner.