MXPA99005512A - Molybdenum complexes containing lubricant compositions - Google Patents

Abstract

The invention relates to lubricating oil compositions comprising a major amount of an oil of lubricating viscosity and a minor amount of at least one compound containing a heterometallic tetranuclear core, preferably cubane, more preferably thiocubane, having 1, 2 or 3 molybdenum atoms, the other metal atoms being Co, Cr, Cu, Ni, W, Mn, Zn or Fe, preferably Cu, and bonded thereto ligands capable of rending the compound oil-soluble or oil-dispersible. The formulated lubricating oil has enhanced friction reducing and anti-wear properties.

Description

LUBRICATING COMPOSITIONS CONTAINING MOLYBDENUM COMPLEXES The present invention relates to lubricating compositions, and to a method for manufacturing them. BACKGROUND OF THE INVENTION Molybdenum disulfide is a known lubricating additive. Unfortunately, it has certain known drawbacks, some of which are caused by its insolubility in lubricating oils. Accordingly, certain molybdenum sulfur-containing oil-soluble compounds have been proposed and investigated as lubricant additives. Patents of the United States of North America Numbers US-A-2,951,040; -3,419,589; -3,840,463; -4,966,719; 4,995,966; and 4,978,464, are illustrative of the descriptions of the oil-soluble molybdenum compounds and their preparation. U.S. Patent No. US-A-4,705,641 describes the mixing of certain copper salts and molybdenum salts in a base supply as antioxidants and anti-wear substances, and Shibahara, Coord. Chem. Rev. 123, 730148 (1993) discloses certain molybdenum and heteronuclear compounds. United States Patent Number US-A-4, 730, 064 describes mixed copper-molybdenum complexes. However, none of the above describes the uses or benefits of copper / molybdenum / sulfur complexes in lubrication. There is a continuing need for additives that demonstrate improved lubricating properties, particularly friction and / or anti-wear reduction, and antioxidation, and which are compatible with the existing additive packages. The present invention solves this need. SUMMARY OF THE INVENTION In a first aspect, the invention is a lubricating oil composition comprising, or being made by mixing, a greater amount of an oil of lubricating viscosity, and as an additive, a smaller amount of at least one compound containing a heterometallic tetranuclear nucleus having 1, 2, or 3 molybdenum atoms, the other metal atoms being Co, Cr, Cu, Ni, Mn,, Zn, or Fe, and linked thereto, ligands capable of making that the compound is soluble in oil or dispersible in oil. Preferably, the core is a Cuban core, optionally including S atoms in a thiocuban core. Additionally, oxygen and selenium can replace sulfur in the nucleus of many of these compounds. The tetranuclear compounds are useful in the formulation of lubricating oil compositions having better lubricating (i.e., friction reduction and anti-wear) properties. In a second aspect, the invention is a method for the preparation of a compound as defined in the first aspect of the invention, and having a thiocuban core, which method comprises reacting a source of mono-, di-, or tri-molybdenum, a source of the other metal atoms, and a source of the ligands, e.g. in a liquid medium, to form said compound. The present invention also provides, in a third aspect, a method for lubricating mechanical components of engines, particularly an internal combustion engine, by the addition of a lubricating viscosity oil containing at least one compound as defined in the first aspect of the invention, and operate the engine. In a fourth aspect, an additive concentrate for mixing with lubricating oils is also included, which comprises an oleaginous vehicle with one or more additives, including an additive as defined in the first aspect of the invention, wherein the concentrate contains 1 at 90 percent by weight, such as from 1 to 50, based on the weight of the additive concentrate. Also included, in a fifth aspect, is the use of an additive as defined in the first aspect of the invention, to improve one or more lubricating properties of a lubricating oil composition. Preferred compounds have a thiocuban core, and are of the formula M4_, Mo S4LnQz, and mixtures thereof, wherein M represents Co, Cr, Cu, Ni, Mn, W, Zn, or Fe; L represents independently selected ligands; Q represents neutral electron donor compounds; and is on the scale of 1 to 3, preferably 2 to 3, and n is on the scale of 2 to 6, and z is on the scale of 0 to 4. The preferred thiocuban nuclei contain Cu and Mo, and the nuclei most preferred have the formula CuMo3S and Cu Mo2S. The compounds are soluble or dispersible in oil. The lubricant compositions of this invention demonstrate improved lubricating properties, particularly anti-wear and friction reduction properties, and are compatible with other additives used in the formulation of commercial lubricating compositions. DETAILED DESCRIPTION OF THE INVENTION • LUBRICANT VISCOSITY OIL The lubricating compositions of the present invention include a larger amount of lubricating viscosity oil. This oil can be selected from vegetable, animal, mineral, or synthetic oils. The oils can have a viscosity from light mineral distillate oils to heavy lubricating oils, such as gas engine oil, mineral lubricating oil, motor vehicle oil, and heavy duty diesel oil. The oils may be unrefined, refined, and re-refined. In general, the viscosity of the oil will be 2 mm2s "1 to 30 mm s, and especially in the scale of 5 mm - 2s" -1 to 20 mm-.2s --.- "1 to 100 ° C. »COMPOSED The lower amount of the compound must be an effective amount to produce improved lubricant performance, particularly the friction reduction and / or anti-wear properties in the oil. The lubricating compositions may include a mixture of the compounds containing the heterometallic tetranuclear nuclei of the types disclosed herein, the lubricating oil, and / or any other additives by themselves, and / or any intermediates and reaction products that arise as a re of mixing. In the compounds of the formula M ^. Io S4LnQz, and mixtures thereof, defined above, M is preferably Cu; L preferably represents independently selected, preferably monoanionic, ligands having organ, preferably hydrocarbyl, groups with a sufficient number of carbon atoms to make the compound soluble or dispersible in the oil; and Q preferably represents water, amines, alcohols, phosphines, and ethers. For example, when the compound is a dicobre-dimolybdenum-ur complex, M is Cu, and is 2, n is 4, and z is 2, and when the compound is a mono-copper-trimolybdenum-ur compound, M is Cu, and is 3, n is 5, and z is from 0 to 1.

The ligands, or ligands L, can be independently selected from the group of: - X •. and mixtures thereof, wherein X, X1, X2, and Y are independently selected from the oxygen and sulfur group, and wherein R1, R2, and R are independently selected from the group consisting of hydrogen and groups organ that can be the same or different. Preferably, the organ groups are hydrocarbyl groups, such as alkyl groups (e.g., wherein the carbon atom attached to the remainder of the ligand is primary, secondary, tertiary), aryl, substituted aryl, and ether. Most preferably, all ligands are the same. It is important that the organ groups of the ligands have a sufficient number of carbon atoms to make the compound soluble or dispersible in the oil. The solubility or dispersibility in oil of the compound can be influenced by the number of carbon atoms in the ligands. In the compounds of the present invention, the total number of carbon atoms present among all the organ groups of the ligands of the compounds will normally be at least 21, such as from 21 to 800, such as at least 25, at least 30. , or at least 35. Preferably, the selected ligand source has a sufficient number of carbon atoms to make the compound soluble or dispersible in the oil. For example, the number of carbon atoms in each alkyl group will generally be between about 1 and 100, preferably from 1 to 40, and more preferably between 3 and 20. Preferred ligands include dialkyl dithiophosphate ("ddp") , xanthates, thioxantates, dialkyl phosphates, dialkyl dithiocarbamate ("dtc"), and dialkyl thiophosphates, and of these, dialkyl dithiocarbamate is more preferred. Organic ligands that contain at least two of the above functionalities are also capable of binding to at least one of the nuclei, and serving as ligands. Ligands can be multidentate. Without the desire to be bound by any theory, it is believed that one or more cores can be linked or interconnected by means of at least one multidentate ligand. This includes the case of a multidentate ligand that has multiple connections to a core. These structures fall within the scope of this invention. Those skilled in the art will recognize that the formation of the compounds requires the selection of ligands that have the appropriate charges to balance the charge of the core. The term "hydrocarbyl" denotes a substituent having carbon atoms directly attached to the remainder of the ligand, and is of a predominantly hydrocarbyl character within the context of this invention. These substituents include the following: (1) hydrocarbon substituents, ie, aliphatic (eg, alkyl or alkenyl), alicyclic (eg, cycloalkyl or cycloalkenyl) substituents, aromatic substituted aliphatic, aliphatic, and alicyclic, and the like, as cyclic substituents wherein the ring is completed through another portion of the ligand (i.e., any two indicated substituents can together form an alicyclic group); (2) substituted hydrocarbon substituents, ie those containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbyl character of the substituent. Those skilled in the art will be aware of suitable groups (for example, halogen, especially chlorine or fluorine, amino, alkoxy, mercapto, alkyl mercapto, nitro, nitroso, sulfoxy, etc.); (3) hetero substituents, that is, substituents which, although predominantly of a hydrocarbon character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms. It is believed that compounds having the formula M4_ Mo S4LnQz useful as additives in the present invention have at least one Cuban nucleus, preferably thiocuban, of the formula M4.yMoyS4, surrounded by ligand, wherein M, yy, Ln , and Qz, are as defined above. The Cuban nuclei are illustrated by the structures: wherein M is selected from the metals described above. When M is Cu, the preferred cores are illustrated by PlO through the following structures: for the Cu-, Mo2S4 core; Y for the Cu Mo3S4 core. The compounds useful as additives in the present invention can be prepared in general as follows: Soluble or oil dispersible tetranuclear thiocuban compounds can be prepared by reacting a source of molybdenum with a source of components of a metal other than molybdenum ("M" as defined above), for example, in suitable liquids / solvents; if desired, additional ligands can be included in the reaction, or they can be added once an initial complex is formed. For example, tetranuclear thiocuban compounds with 3 molybdenum atoms can be synthesized by reaction of a trinuclear molybdenum source, such as Mo3S4 (dtc) 4 with a metal source other than molybdenum ("M"), where M is as described above), such as CuCl, followed by substitution by ligand, with a ligand such as thiolate. In a similar manner, a tetranuclear thiocuban compound with two molybdenum atoms can be synthesized by reacting a dinuclear molybdenum source, such as Mo2S (dtc) 2, with a metal source other than molybdenum ("M"). as described above), such as CuCl, followed by ligand substitution, with a ligand such as a carboxylate. Tetranuclear thiocuban compounds can be synthesized with a molybdenum atom by reaction of a molybdenum source such as Mo (CO) 6, with a metal source other than molybdenum ("M" as described above), and a source of ligand, such as M3S4 (dtc) 4 and a source of ligand such as thiuram disulfide. Suitable liquids / solvents can be, eg, aqueous, or organic. In general, the compounds can be purified by well-known techniques, such as chromatography; however, it may not be necessary to purify the compounds. The lubricant compositions contain effective minor amounts, preferably from 1 ppm to 2,000 ppm molybdenum, from the compounds containing the heteromethalic tetranuclear core (of the types described above), such as from 5 to 1,000, preferably 20 to 1,000, more preferably from 5 to 750 ppm, and most preferably from 10 to 300 ppm, all based on the weight of the lubricant composition. For example, with the compounds containing copper-molybdenum-sulfur, the improvement in lubricant performance can be seen in the Cu concentrations from the compounds containing heterometallic tetranuclear core (of the types described above) of at least 1 ppm at 1,000 ppm, preferably from 1 to 200 ppm. Within the above ranges, an expert in this field can select the particular combination of desired amounts to produce the improvement in the oxidation and lubrication (friction reduction and / or anti-wear) properties desired for the particular application. The selection within these ranges can be made to optimize the best performance against oxidation, reduction of friction, or against the wear of the three. These benefits can be achieved in a base supply, as well as in fully formulated lubricating oils. Also oils substantially free of phosphorus and / or free of sulfur can be treated. A lubricant composition that is essentially or substantially free of phosphorus and / or sulfur is one in which the amount of phosphorus and / or sulfur is not greater than what is inherently present in base oils of lubricating viscosity. The lubricating oil compositions of the present invention can be prepared by combining a larger amount of a lubricating viscosity oil, and a lower effective amount of compounds containing the heterometallic tetranuclear nuclei., which are described more specifically above. This preparation can be carried out by mixing the complex directly with the oil, or by first combining the complex in a suitable carrier fluid to achieve solubility or dispersibility in oil, and then adding the mixture to the lubricating oil. Concentrates of the compounds in an oleaginous vehicle, preferably hydrocarbon, provide a convenient means for handling the compounds before use.

Lubricating viscosity oils, such as those described above, as well as aliphatic, naphthenic, and aromatic hydrocarbons, are examples of suitable carrier fluids for concentrates. These concentrates may have from 1 to 90 weight percent of the compound, based on the weight of the concentrate, such as from 1 to 50; preferred is 1 to 70 weight percent, more preferably 20 to 70 weight percent. Or they may contain from 1 to 200,000 ppm by weight, for example from 50 to 150,000, such as from 50 to 100,000 molybdenum of an additive of this invention, based on the weight of the concentrate. Lubricating oil compositions made by the combination of an oil of lubricating viscosity herein, and at least one compound containing a heteromethallic tetranuclear core, preferably Cuban, of the types and in the amounts described herein, may be Use to lubricate mechanical components of engines, particularly an internal combustion engine, by adding the lubricating oil composition to it. The terms "oil soluble" or "dispersible" used herein, do not necessarily indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. However, it does mean that they are, for example, soluble or stably dispersible in oil to a sufficient degree to exert their intended effect in the environment in which the oil is used. Moreover, the further incorporation of other additives may also allow the incorporation of higher levels of a particular additive, if desired. Conveniently, the use of a compound containing the heterometallic tetranuclear nuclei as described in the present invention, may decrease the need for the use of separate metal additives, for example copper and molybdenum, thus providing an opportunity for decrease the combined costs of mixing and related costs. The known lubricant additives can also be used to mix in the lubricant compositions of this invention. These include, for example, those containing phosphorus, dispersants, detergents, e.g. single or mixed metal, melting point depressants, viscosity improvers, antioxidants, surfactants, other friction modifiers, and anti-wear substances. These can be combined in proportions known in the art. It will be understood that the different components of the composition, the essential components, as well as the optional and customary components, can react under the conditions of formulation, storage, or use, and that the invention also provides the product that can be obtained or it gets as a result of any of these reactions. EXAMPLES The invention will be more fully understood by reference to the following examples that illustrate different modifications of the invention, which should not be construed to limit its scope. As used herein, "coco" is an alkyl chain or mixtures of chains of different even numbers of carbon atoms, usually 8 to 18 carbon atoms. The procedures and equipment used for the Falex Ring Block tests herein were similar to those used in ASTM G77-83 (Slip Wear Resistance Classification Using the Ring Block Wear Test). Example 1: Synthesis of Cu-Mo-S ^ (coconut-, dtc) .- (dodecylthiolate) -, Copper (I) chloride (0.2 grams, 2 mmol) and Mo-S4 (coconut-dtc) were mixed together. 2 (1.2 grams, 1 millimole) in a 1: 1 solution of dichloromethane and methanol (total volume of 50 milliliters), and stirred at room temperature for 8 hours. Then a solution in methanol (25 milliliters) of potassium dodecylthiolate (0.51 grams) was added, 2 millimoles) to the solution containing copper-molybdenum. Additional dichloromethane (50 milliliters) was added to the flask, and the solution was stirred for 24 hours. The dichloromethane was distilled, and the methanol was decanted. The tarry material from the bottom of the flask was dissolved in pentane, filtered, and dried under vacuum to give Cu2Mo2S4 (coco2dtc) 2 (dodecylthiolate) 2. E-example 2: Synthesis of Cu2Mo-, S4 (coconut-, dtc) - (oleate). Copper (I) chloride (0.2 grams, 2 mmol), and Mo2S4 (coconut-dtc) 2 (1.2 grams, 1 mmol), were mixed together in a 1: 1 solution of dichloromethane and methanol (total volume of 50 milliliters), and stirred at room temperature for 8 hours. Then a solution in methanol (25 milliliters) of potassium oleate (0.67 grams, 2 millimoles) was added to the solution containing copper-molybdenum. Additional dichloromethane (50 milliliters) was added to the flask, and the solution was stirred for 24 hours. The dichloromethane was distilled, and the methanol was decanted. The tarry material at the bottom of the flask was dissolved in pentane, filtered, and dried under vacuum, to give Cu2Mo2S4 (coco2dtc) 2 (oleate) 2. Example 3: Synthesis of CuMo3S (octyl-, dtc) 4 (dodecylthiolate) Copper (I) chloride (0.1 grams, 1 millimole), and Mo3S4 (octyl2dtc) 4 (1.68 grams, 1 millimole) were added to tetrahydrofuran ("THF") (50 milliliters), stirred at room temperature for 24 hours , and the reaction was filtered. Then a solution in methanol (10 milliliters) of potassium dodecylthiolate (0.25 grams, 1 millimole) was added to the copper-molybdenum filtrate. The combined solution was stirred for 8 hours, after which the tetrahydrofuran was distilled off, the tar was redissolved in pentane, the solution was filtered, and the pentane was distilled to give CuMo3S4 (octyl2dtc) 4 (dodecylthiolate). Example 4; Synthesis of CuMo3S (oc il.-ddp) 4 (dodecylthiolate) Copper (I) chloride (0.1 grams, 1 millimole), and Mo3S4 (octyl2ddp) 4 (1.83 grams, 1 millimole) were added to tetrahydrofuran (50 milliliters), they were stirred at room temperature for 24 hours, and the reaction was filtered. Then a solution in methanol (10 milliliters) of potassium dodecylthiolate (0.25 grams, 1 millimole) was added to the copper-molybdenum filtrate. The combined solution was stirred for 8 hours, after which the tetrahydrofuran was distilled, the tar was redissolved in pentane, the solution was filtered, and the pentane was distilled to give CuMo3S4 (octyl2ddp) 4 (dodecylthiolate). In Examples 5 to 8, the compounds of the invention were evaluated to determine their friction and wear performance in a Falex Ring Block test procedure. The data was acquired at a speed of 420 revolutions per minute (44 radians / second), 220 pounds (100 kilograms), and a temperature of 100 ° C for 2 hours. In Examples 5-9, the samples tested consisted of 150 Neutral Solvent Oil (S150N), 1% zinc dialkyldithiophosphate ("ZDDP"), and the additive compounds containing 500 ppm molybdenum, based on weight total lubricating oil. The coefficients of friction are reported as the end of the test value, and as the average value during the two hours. The reported data included the volume of the block wear mark, measured by profilometry, the coefficient of friction at the end of the test ("Last Coefficient"), and the average coefficient of friction ("Average Coefficient"), obtained during the Two-hour test. The coefficient of friction at the end of the test is the coefficient of friction determined at the end of the test period, and the average coefficient of friction provides information on the activity of the aggregate material, that is, it is considered that the samples that obtain the same coefficients faster friction, contain more friction reducing active compounds. Example 9 (Comparative) For comparison purposes, the Falex Ring Block was conducted using only 150 Neutral Solvent (S150N), and 1 percent zinc dialkyldithiophosphate. The results are shown in Table I.

TABLE I S150N + 1% ZDDP + Additive (in 500 ppm Mo) In Examples 10 to 12, the compounds were evaluated for friction and wear performance in a Falex Ring Block test procedure. The data were obtained at a speed of 420 revolutions per minute (44 radians / second), 220 pounds (100 kilograms), and a temperature of 100 ° C for 2 hours. In Examples 10-13, the samples tested consisted of fully formulated 10W30 motor oil, combined with the additive compounds containing 500 ppm molybdenum, based on the total weight of the lubricating oil. Example 13 (Comparative) For comparison purposes, the Falex Ring Block test was conducted using a fully formulated 10 30 motor oil. The results are shown in Table II. TABLE II 10 30 + Additives (in 500 ppm of Mo)

Claims (17)

1. NOVELTY OF THE INVENTION Having described the foregoing invention, it is considered as a novelty, and therefore, property is claimed as contained in the following: CLAIMS 1. A lubricating oil composition comprising, or made by mixing , a larger amount of a lubricating viscosity oil, and as an additive, a minor amount of at least one compound containing a heterometallic tetranuclear nucleus having 1, 2, or 3 molybdenum atoms, the other metal atoms being, Co, Cr, Cu, Ni, Mn, W, Zn, or Fe, and linked thereto, ligands capable of rendering the compound oil soluble or oil dispersible.
2. 2. The composition according to claim 1, characterized in that the nucleus is a cuban nucleus, optionally including S atoms in a thiocuban nucleus.
3. 3. The composition as claimed in any of the preceding claims, characterized in that the compounds have the formula M Mo S4Ln z, wherein M represents Co, Cr, Cu, Ni, Mn,, Zn, or Fe; L represents independently selected ligands; Q represents neutral electron donor compounds; and is on the scale of 1 to 3; n is on the scale of 2 to 6; yz is on the scale from 0 to 4.
4. The composition according to ls claimed in claim 3, characterized in that the formula is CuMo3S 5Qz or Cu2Mo2S4L4Qz, wherein L, Q, and z are as defined in claim 3.
5. The composition according to claim 3 or claim 4, characterized in that the ligands, or ligands L, are represented by at least one structure having the formula -X-R, wherein X, X-, X2, and Y are oxygen or sulfur, and wherein R1, R2, and R independently represent hydrogen atoms or organ groups, such as hydrocarbyl groups.
6. 6. The composition according to claim 5, characterized in that the organ groups independently represent alkyl, aryl, substituted aryl, or ether groups.
7. The composition according to claim 6, characterized in that the organ groups are alkyl groups, each having from 1 to 100, for example from 1 to 40, such as from 3 to 20 carbon atoms.
8. The composition as claimed in any of claims 5 to 7, characterized in that the total number of carbon atoms in all organ groups of the ligands is at least 21, such as 21 to 800.
9. 9 The composition as claimed in any of the preceding claims, characterized in that the ligands are, or L independently represents, dialkyl dithiophosphate ligands, thioxanthate, dialkyl phosphate, dialkyl dithiocarbamate, dialkyl thiophosphate, or xanthate.
10. 10. The composition as claimed in any of the preceding claims, characterized in that the weight of Mo of the compounds is at least 1 ppm, for example from 1 to 2,000 ppm of Mo, such as from 5 to 1,000, of 20 to 1,000 preference, based on the weight of the lubricating oil composition.
11. 11. The composition as claimed in claim 10, characterized in that the Mo is present in an amount of 5 to 750 ppm Mo, based on the weight of the lubricating oil composition.
12. 12. The composition as claimed in any of claims 2 to 11, characterized in that the thiocuban core is represented by the structure: wherein M is defined as in claim 3.
13. The composition as claimed in any of the preceding claims, characterized in that it further comprises one or more dispersants, detergents, melting point depressants, viscosity modifiers, surfactants, substances against wear, and antioxidants.
14. 14. An additive concentrate to be mixed with a lubricating viscosity oil, which comprises, or is made by mixing, an oleaginous vehicle, and from 1 to 200,000 ppm by weight, for example from 50 to 150,000, such as from 50 to 100,000, of the molybdenum of an additive as defined in any of claims 1 to 12, based on the weight of the concentrate.
15. 15. An additive concentrate for mixing with an oil of lubricating viscosity, which comprises, or is made by mixing, an oil vehicle with one or more additives, including an additive as defined in any of claims 1 to 12, wherein the concentrate contains from 1 to 90 percent, such as from 1 to 50, of additives, based on the weight of the concentrate.
16. 16. A method for lubricating an internal combustion engine, which comprises operating the engine, and lubricating the end with a lubricating oil composition in accordance with claim 1 of any of claims 1 to 13.
17. 17. The use of an additive or additives according to claim 1 in any of claims 1 to 12, to improve one or more lubricating properties of a lubricating oil composition.