3,505,222 United States Patent Office Patented Apr. 7, 1970 1. 2 3,505,222 product of a mercaptain with sulfur trioxide. Their metal LUBRICANT COMPOSITIONS salts are represented by the formula: Leonard M. Niebylski, Birmingham, Mich, assignor to O Ethyl Corporation, New York, N.Y., a corporation of Virginia (R-S-S-0--M No Drawing. Filed Mar. 29, 1967, Ser. No. 626,701 5 s (I) Int. C. C10m 5/14, 3/18, 7/36 wherein R is a hydrocarbon radical containing from 1 U.S. C. 252-17 2 Claims to about 30 carbon atoms, M is a metal, and n is the valence of metal M. For example, when M is the monova 0. lent sodium ion, n is 1. ABSTRACT OF THE DISCLOSURE The radical R can be an alkyl, cycloalkyl, aralkyl, The extreme pressure wear properties of base lubri alkaryl, or aryl radical. The radicals may contain other cants including water, hydrocarbons, polyesters, silicones, nonhydrocarbon substituents such as chloro, bromo, iodo, polyethers and halocarbons is enhanced by the addition fluoro, nitro, hydroxyl, nitrile, isocyanate, carboxyl, car of a synergistic mixture of a thiosulfate compound and 15 bonyl, and the like. a lead compound. The useful metals are all those capable of forming Bunte salts. Preferred metals are those previously listed as suitable for forming metal thiosulfates. Of these, the Background more preferred metals are sodium and lead, and lead is 20 the most preferred metal in the Bunte salts. This invention relates to improved lubricant composi Examples of useful Bunte salts include: tions. Many lubricants which are satisfactory for ordinary sodium S-lauryl thiosulfate lubricating applications do not provide adequate protec potassium S-methylthiosulfate tion under the extreme conditions of high load. These lead S-isoamyl thiosulfate high load conditions are encountered in such applications 25 mercury S-n-cetylthiosulfate as cutting oils, extrusion lubricants and bearing lubrica silver S-(1-methylnonadecyl)thiosulfate tion. Present lubricants made for these purposes include tin S-phenylthiosulfate sulfurized and chlorinated hydrocarbon oils and oils con calcium S-triacontylthiosulfate taining such additives as iodine or molybdenum sulfide. barium S-hexacosylthiosulfate Summary 30 zinc S-cyclohexylthiosulfate lead S-(2-chlorohexyl)thiosulfate An object of this invention is to provide an extreme sodium S-(meta-nitrophenyl)thiosulfate pressure wear additive for a variety of lubricating base strontium S-(2-ethyloctyl) thiosulfate oils. This additive greatly increases the lubricity of these cobalt S-(2-iodobutyl)thiosulfate base oils under conditions of extremely high load. This 35 nickel S-(3,5-di-iodobenzyl)thiosulfate and other objects are accomplished by providing a syner lead S-(3,5-di-tert-butyl-4-hydroxybenzyl)thiosulfate gistic friction-reducing composition comprising a mixture molybdenum S--(1-methyl-n-pentadecyl) thiosulfate of at least two different compounds, said mixture com copper S-phenylthiosulfate prising (A) from 1 to about 99 weight percent of a thio potassium S-(4-methylphenyl)thiosulfate sulfate compound, and (B) from about 1 to 99 weight 40 sodium S-(3,5-dibromophenyl)thiosulfate percent of a lead compound. The lubricity of a wide range of base lubricants is greatly improved by merely adding a The preferred Bunte salts are those having Formula I friction-reducing amount of the above synergistic compo wherein R represents an alkyl radical having from 1 to sition. The amount of synergistic mixture used can vary about 30 carbon atoms and M is sodium or lead. Exam over a wide range depending upon the base lubricant em 45 ples of these are: ployed and the specific application for which the lubricant sodium S-laurylthiosulfate is designed. Generally good results are obtained when lead S-lauryl thiosulfate from about 0.01 to 30 weight percent of the synergistic sodium S--(1-methylnonadecyl)thiosulfate mixture is added. A more useful range of the synergistic lead S-methylthiosulfate mixture is from about 0.1 to 25 weight percent, and a 50 Sodium S-triacontylthiosulfate . most useful range is from about 0.5 to 20 weight percent lead S-n-propylthiosulfate of the synergistic mixture. Useful thiosulfate compounds are those which contain The most preferred Bunte salt is lead S-lauryl thiosulfate. the thiosulfate radical: Another useful class of thiosulfates are the quaternary 55 ammonium thiosulfates. These are made by the reaction of quaternary ammonium halides with a metal thiosulfate O as shown below. S O i. i. 60 2Ri-N-R) C -- Na2S2O3 - (R-N-Rasso, -- 2NaCl 4. R4 One class of such compounds consists of the metal salts (II) of thiosulfuric acid such as the thiosulfates of lithium, Hence, another embodiment of this invention is a lubri sodium, potassium, calcium, barium, magnesium, stron cating composition comprising a base lubricant and a tium, zirconium, cadmium, zinc, nickel, manganese, co 65 friction-reducing amount of a mixture of at least two balt, copper, aluminum, molybdenum, iron, lead, tin, compounds, one of which is a lead compound and the silver, mercury, germanium, and the like. Of the fore other is a quaternary ammonium thiosulfate having For going, the more preferred thiosulfates are sodium thio mula II wherein R1, R2, R3 and R4 are hydrocarbon radi sulfate and lead thiosulfate, with lead thiosulfate being cals containing from 1 to about 30 carbon atoms. Some ex the most preferred. 70 amples of the quaternary ammonium thiosulfates are: Another group of useful thiosulfate compounds are the tetramethyl ammonium thiosulfate metal salts of Bunte acids. Bunte acids are the reaction trimethyl lauryl ammonium thiosulfate 3,505,222 3 4. triethyl lauryl ammonium thiosulfate EXAMPLE 5 trimethyl eicosyl ammonium thiosulfate trimethyl triacontyl ammonium thiosulfate To a solvent-extracted Pennsylvania bright stock hav trimethylphenyl ammonium thiosulfate ing a viscosity of 500 SUS at 100 F. is added 7 percent trimethylbenzyl ammonium thiosulfate of lead S-octadecyl thiosulfate and 3 percent of lead as trimethyl (3,5-di-tert-butyl-4-hydroxybenzyl) thiosulfate 5 lead imidazole. trimethyl p-isoamylphenyl ammonium thiosulfate EXAMPLE 6 trimethyl p-isooctylbenzyl ammonium thiosulfate To a polybutene oil having a viscosity of 114 SUS The other component forming the synergistic friction at 100 F. is added 0.5 percent of a finely-divided lead reducing composition is a lead compound. It may be O thiosulfate and 1 percent of lead as lead naphthenate. soluble or insoluble in the base lubricant. Some examples EXAMPLE 7 of suitable compounds include lead sulfide, lead carbon To a polymerized trimethylethylene having a viscosity ate, lead oxides, tetraaikylleads such as tetramethylead, of 367 SUS at 100 F. is added 3 percent of a finely tetraethylead, tetravinyllead, ethyltrimethylead, dinneth divided silver thiosulfate and 0.1 percent of lead as lead yldiethylead, and the like. S-triacontyl thiosulfate. Another class of lead components includes the previ The synergistic additives are useful in a wide range ously-described Bunte salts wherein the metallic ingredi of hydrocarbon-derived greases containing various metal ent is lead. Oil solubility is imparted to the Bunte salt soaps as thickening agents such as calcium stearate, lead by the R radical. In order to accomplish this, it is pre 20 oleate or sodium oleate. The following examples will ferred that the R group is an alkyl radical containing from serve to illustrate the use of the synergistic mixtures as about 10 to 30 carbon atoms. Of course, when the lead extreme pressure friction-reducing agents in some hydro compound is a lead Bunte salt, the thiosulfate component carbon-derived greases. must be a different thiosulfate including a Bunte salt of a metal other than lead compound in order to obtain the EXAMPLE 8 synergistic interaction. To a calcium oleate thickened grease containing about The more preferred lead compounds are lead naphthe 82 percent of a hydrocarbon oil having a Saybolt vis nate, lead imidazole, lead isodecyl Xanthogenate, lead cosity at 100 F. of 300 is added 5 percent of lead thio oleate, lead stearate, lead sulfide, and lead n-octyl xantho sulfate and 3 percent of lead as lead naphthenate. genate. Of the foregoing, the most preferred lead com pound is lead naphthenate. The most preferred syner 30 EXAMPLE 9 gistic friction-reducing combination is a mixture of lead To a lead oleate thickened grease containing about thiosulfate with lead naphthenate. 94 percent of a Pennsylvania mineral oil having a Say The following examples illustrate the synergistic fric bolt viscosity at 100 F. of 200 is added 3 percent of tion-reducing compositions: 1 percent sodium thiosulfate sodium thiosulfate and 1 percent of lead as lead imidazole. plus 99 percent lead naphthenate; 99 percent sodium thio sulfate plus 1 percent lead naphthenate; 50 percent silver EXAMPLE 10 thiosulfate plus 50 percent lead sulfide; 75 percent alu To a calcium stearate thickened grease containing minum thiosulfate plus 25 percent lead S-laury1 thiosul about 87 percent of a California mineral oil having a fate; and 25 percent trimethyl lauryl ammonium thio 40 Saybolt viscosity at 100 F. of 241 is added 20 percent sulfate plus 75 percent lead imidazole. of barium S-isoamyl thiosulfate and 5 percent of lead Suitable base lubricants include hydrocarbon-derived as lead naphthenate lubricating oils and greases, polyester lubricants, silicone EXAMPLE 11 oils, polyethylene oils, and haiohydrocarbons. To a grease containing 88 percent of a California Hydrocarbon oils include those of a wide viscosity 45 mineral oil having a Saybolt viscosity at 100 F. of 300 range of from about SAE-5 to SAE-90. These oils can and thickened with a mixture of calcium stearate and be prepared using any of the well-known refining methods calcium oleate is added 15 percent of tetramethyl am such as solvent refining. When the oils are to be used as monium thiosulfate and 5 percent of lead as triethyllead cutting oils, it is preferred that they have a viscosity of chloride.