MXPA00003153A - Lubricating composition comprising a friction reducing additive package and greases - Google Patents

Abstract

A lubricating composition comprising a base oil in combination with molybdenum dithiocarbamate, zinc naphthenate and one or more metal dithiophosphates, and optionally one or more metal dithiocarbamates. A lubricating grease comprising such a composition in combination with a thickener, is particularly suitable for lubricating constant velocity joints.

Description

LUBRICANT COMPOSITION COMPRISING A CONTAINER AND FRICTION REDUCING ADDITIVE FATS FIELD OF THE INVENTION The present invention relates to lubricating compositions, more particularly, though not exclusively, to lubricating greases containing such compositions, and more particularly, but not exclusively, to lubricating greases for use in constant velocity joints such as velocity joints. mobile constant.

BACKGROUND OF THE INVENTION The constant speed joints are used for cars with front / front-wheel drive, cars with independent suspension, or in vehicles with four-wheel drive. Constant speed joints (CVJ) are special types of universal couplings that transmit the traction from the final reduction gear to the axle of a car steering wheel. The two most important categories of board REF .: 33103 constant speed are fixed and mobile constant speed joints, and are usually used in a vehicle in appropriate combinations. The mobile CVJ allow the sliding in the axial direction, while the fixed CVJ do not allow the movement in the axial direction. The mechanical components of the moving joints are subjected to complex rolling and sliding movements when the joint is at a certain angle and is subject to rotation, and it is known that the frictional resistance to these movements can cause the automotive vehicle to suffer vibrations , acoustic noises in the form of knocking, and small rolling movements, particularly in certain driving conditions. Such noises, vibrations and movements can be unpleasant for the occupants of the vehicle. Accordingly, attempts have been made to formulate grease for CVJ in order to improve its frictional characteristics in order to reduce the frictional forces within the movable constant velocity joints, as well as reduce the noise and vibrations suffered in the automobiles. . A series of studies has shown that there are useful correlations between these noises and vibrations and the coefficients of friction measured in certain laboratory machines for friction tests. In particular, it has been found in a number of studies that the SRV laboratory machine (Schwingungs Reibung und Verschleiss) for friction testing (manufactured by Optimol Instruments) provides a useful guide in the development of grease for constant speed friction joints, to improve the characteristics of noise and vibration. Examples of lubricating greases commonly used in such constant velocity joints include a fat comprising a calcium complex soap as a thickening agent; a fat comprising a lithium soap as a thickening agent; a fat comprising a lithium complex as a thickening agent; and a fat comprising a polyurea as a thickening agent. However, the thickeners may be any of a variety of materials including clays, and calcium, sodium, aluminum and barium fatty acid soaps. The base oils used in lubricating greases are essentially the same type of oil that would normally be selected for oil lubrication. The base oils may be of mineral and / or synthetic origin. The base oils of mineral origin may be mineral oils, produced for example by refining or hydroprocessing. The base oils of synthetic origin can typically be mixtures of C10-50 hydrocarbon polymers, for example liquid polymers of alpha-olefins. They can also be conventional esters, for example polyol esters. The base oil can also be a mixture of these oils. Preferably, the basic oil is that of mineral origin sold by the Royal Dutch / Shell Group of Companies under the designations WHVI "or" MVIN ", is a polyalphaolefin, or a mixture thereof. Base oils of the type manufactured by means of hydroisomerization of wax can also be included, such as those sold by the Royal Dutch / Shell Group of Companies under the name "XHVI" (brand). The lubricating grease preferably contains 2 to 20% by weight of thickener, preferably 5 to 20% by weight. Fats thickened with lithium soap have been known for many years. Typically, lithium soaps are derivatives of saturated fatty acids or unsaturated C? 0-2_, preferably C? 5? 8, or derivatives thereof. A particular derivative is hydrogenated castor oil, which is the glyceride of 12-hydroxystearic acid. The 12-hydroxystearic acid is a fatty acid of particular preference. Thickened fats with complex thickeners are well known. In addition to the salt of a fatty acid, they incorporate into the thickener a complexing agent which is commonly an acid or dibasic acid of low molecular weight to medium or a salt thereof, such as benzoic acid or boric acid or a lithium borate. The urea compounds used as thickeners in fats include in their molecular structure the urea group (-NHCONH-). These compounds include mono, di or polyurea compounds, according to the number of urea linkages. Various conventional additives for greases can be incorporated into lubricating greases, in amounts normally used in this field of application, to impart to the fat certain desirable characteristics, such as oxidation stability, adhesion, extreme pressure properties, and corrosion inhibition. . Suitable additives include one or more extreme pressure / antiwear agents, for example zinc salts such as dialkyl or zinc diaryldithiophosphates.; borates; substituted thiadiazoles; polymeric nitrogen / phosphorus compounds made for example by reacting a dialkoxyamine with a substituted organic phosphate *; amine phosphates; sulfuric whale oils of natural or synthetic origin; sulfurized butter; sulphurous esters; esters of sulfurized fatty acids; and similar sulfur materials; organophosphates, for example, according to the formula (OR) 3 P = 0 where R is an alkyl, aryl or aralkyl group; and triphenyl phosphorothionate; one or more detergents containing overbasic metals, such as calcium or magnesium alkylsalicylates or alkylarylsulfonates; one or more ashless dispersant additives, such as reaction products of polyisobutenylsuccinic anhydride and an amine or ester; one or more antioxidants, such as phenols or sterically hindered amines, for example phenyl-alpha-naphthylamine, diphenylamine or alkylated diphenylamine; one or more anti-corrosion additives such as oxygenated hydrocarbons that have been optionally neutralized with calcium, calcium salts of alkylated benzene sulfonates and alkylated benzene petroleum sulfonates, and succinic acid derivatives, or friction modifying additives; one or more viscosity index improver agents; one or more additives reducing the runoff temperature; and one or more adhesion agents. Solid materials such as graphite, finely divided MoS2, talc, metal powders, and various polymers such as polyethylene wax can also be added to impart special properties. Studies carried out with soluble molybdenum dithiocarbamates (MoDTC) (PCH Mitchell, Wear 100 (1984) 281, H. Tsoyama and T. Sakurai, Tribology International 7 (1974) 151, ER Brathwaite and AB Greene, Wear 46 (1970) 405; and Y. Yamamoto and S. Gondo, Tribology Trans., 32 (1989) 251) and with other organomolybdene compounds in the presence of sulfur-containing materials (Y. Yamamoto, S. Gondo, T. Kamakura and M. Konishi, Wear 120 (1987) 51; Y.

Yamamoto, S. Gondo, T. Kamakura and N. Tanaka, Wear 112 (1986) 79; A.B. Greene and T.J. Ridson SAE Technical Paper 811187 Warrendale PA, 1981; and I. Feng, W. Perilstein and M.R. Adams ASLE Trans., 6 (1963), 60) have shown that they are effective in reducing friction and wear. The presence of molybdenum in combination with sulfur (AB Greene and TJ Ridson SAE Technical Paper 811187 Warrendale PA, 1981), and possibly phosphorus (Y. Yamamoto, S. Gondo, T. Kamakura and M. Konishi, Wear 120 (1987 51) It seems to be the necessary condition to achieve low friction.The sulfur source can be an additive used in combination with the molybdenum compound (K. Kubo, Y. Hamada, K. Moríki and M. Kibuka a, Japanese Journal of Tribology , 34 (1989) 307), commonly zinc dithiophosphate (ZnDTP), from the basic oil used (Y. Yamamoto, S. Gondo, T. Kamakura and N. Tanaka, Wear 112 (1986) 79) or obtained from the chemical combination with the molybdenum compound itself (as in the case of the MoDTC) However, there are many cases in the literature where the addition of organomolybdenum-sulfur compounds to the oils did not produce friction reduction The source of sulfur used in combination with the organomolybdenum seems to be critical, some types of ZnDTP p they cause a fall in friction, while others cause a rise in friction (K. Kubo, Y. Hamada, K. Moriki and M. Kibukawa, Japanese Journal of Tribology, 34 (1989) 307). In an NTN study (SAE Technical Paper 871985, The Development of Low Friction and Anti-Fretting Corrosion Greases for CVJ and Wheel Bearing Applications, M. Kato and T. Sato of NTN Tokyo Co. Ltd.), the highest reduction in Friction was found when molybdenum dithiophosphate (MoDTP) was included with ZnDTP in a polyurea based fat. The addition of MoDTC along with ZnDTP to the polyurea based grease brought with it a small reduction in friction. In accordance with the present invention, it has been discovered that the addition of zinc naphthenate to a combination of MoDTC and metal dithiophosphate can improve the properties of these additives in friction matters. This effect is surprising because the addition of zinc naphthenate to molybdenum dithiocarbamate alone does not produce a reduced coefficient of friction, and in fact shows an increase in the coefficient of friction. Accordingly, it has surprisingly been found that a molybdenum dithiocarbamate, a metal dithiophosphate and zinc naphthenate in combination act synergistically as a friction reducing agent in lubricating compositions, especially fats, while retaining good anti-wear properties. Tested against the use of molybdenum dithiocarbamate alone or in combination with one of the other two components, the reduction of friction is quite unexpected. WO 97/03152 discloses a lubricating composition comprising a base oil, molybdenum disulfide, zinc naphthenate and zinc dithiophosphate, and optionally zinc dithiocarbamate. There is no information in this document from which it can be derived that the combination of compounds according to the invention is a good friction reducing agent. EP-A-0770668 refers to lubricating compositions which comprise a base oil, 0.001-5.0% by mass of a selected molybdenum dithiocarbamate, 0.01-5.0% by mass of a selected zinc dithiophosphate, and 0.005-1.0% by mass of a selected copper carboxylate. EPA-A-0770668 does not show the use of zinc naphthalene. The first aspect of the present invention therefore provides a lubricating composition comprising a base oil and, as a friction reducing additive package, a combination of molybdenum dithiocarbamate, zinc naphthenate and one or more metal dithiophosphates, and optionally one or more of other metal dithiocarbamates. Preferably, molybdenum dithiocarbamate - li ¬ is a sulphurized oxymolybdenum dithiocarbamate of the general formula: MOsOmS. wherein the four possible R groups Ri, R2 R3 and R (only Ri and R2 are shown) in the generalized structure can be the same or different, and R? -R4 is each a C? -C30 hydrocarbon or a hydrogen. Preferably, m + n = 4, and m and n may or may not be integers. Preferably, R? ~ R4 each independently represents a primary or secondary alkyl group having from 1 to 24 carbon atoms, cycloalkyl groups having from 6 to 26 carbon atoms, or an aryl or alkylaryl group having from 6 to 30 carbon atoms, or hydrogen. R? -R4 can be chosen to influence the solubility of MoDTC. In metal dithiophosphates and / or metal dithiocarbamates, the metal is preferably independently selected from zinc, molybdenum, tin, manganese, tungsten and bismuth. Preferably, the one or more metal dithiophosphates is / are selected from dialkyl, diaryl or zinc alkylaryldithiophosphates, and the one or more metal dithiocarbamates is / are selected from dialkyl, diaryl or alkylaryldithiocarbamates of zinc, dithiophosphates and / or dithiocarbamates in which any alkyl group is straight or branched chain and preferably contains from 1 to 12 carbon atoms. In accordance with the present invention, there is also provided a lubricating grease comprising a thickener in combination with a lubricating composition in accordance with the present invention. In the lubricating grease according to the present invention, preferably the weight ratio between molybdenum in molybdenum dithiocarbamate and total metal dithiophosphate ranges from 2: 1 to 1:20, and the weight ratio between the metal dithiophosphate and the Zinc naphthenate varies from 0.85: 10 to 0.85: 0.05. and the weight ratio between molybdenum in molybdenum dithiocarbamate and zinc in zinc naphthenate ranges from 15: 1 to 1: 4. More preferably, with molybdenum dithiocarbamate soluble in oil, the weight ratio between molybdenum in molybdenum dithiocarbamate and metal dithiophosphate ranges from 0.8: 1.7 to 0.14: 1.7 and the weight ratio between metal dithiophosphate and naphthenate of zinc varies from 0.85: 4.8 to 0.85: 0.6, and the weight ratio between molybdenum in molybdenum dithiocarbamate and zinc in zinc naphthenate ranges from 5: 1 to 1: 1.6. More preferably, with molybdenum dithiocarbamate insoluble in oil, the weight ratio between molybdenum in molybdenum dithiocarbamate and metal dithiophosphate ranges from 1: 1 to 1: 6.2. and the weight ratio between metallic dithiophosphate and zinc naphthenate ranges from 0.85: 4.8 to 0.85: 0.6, and the weight ratio between molybdenum in molybdenum dithiocarbamate and zinc in zinc naphthenate varies from 10.3: 1 to 1: 0.8. In the above, zinc naphthenate typically represents a complex mixture of naphthenic acids derived from selected fractions of crude oil, typically by reacting the fraction with sodium hydroxide solution, followed by acidification and purification. Preferably, the naphthenic acids, before reaction with a zinc compound, have molecular weights ranging from 150-500, more preferably 180-330. Preferably, the content of elemental zinc in the zinc naphthenate mixture is between 1-25%, most preferably 5-20%, most preferably 9.0-15.4%. The lubricating grease according to the present invention preferably contains molybdenum. of molybdenum dithiocarbamate in the amount of 0.04 to 2.5%, by weight, of Mo, more preferably, with molybdenum dithiocarbamate soluble in oil, 0.08% to 0.6%, by weight, of Mo, and with molybdenum dithiocarbamate insoluble in oil, 0.08% to 1.4%, by weight, of Mo. Preferably, it further contains said one or more metal dithiophosphates in the total amount of 0.1 to 10%, by weight, more preferably 0.3% to 3.5%, by weight. It also contains zinc naphthenate in the amount of 0.05% to 12.0%, by weight, more preferably 0.3% to 3.5%, by weight. The friction reducing additive according to the present invention does not need to contain molybdenum disulfide. Moreover, it is preferred that the lubricant compositions according to the invention do not contain a substantial amount of molybdenum disulfide. It is preferred that the lubricant compositions contain less than 0.5%, by weight, of molybdenum disulfide, more preferably less than 0.3%, by weight, of molybdenum disulfide, with no higher preference of molybdenum disulfide.

The thickener preferably comprises a urea compound, a simple lithium soap or a complex lithium soap. A preferred urea compound is a polyurea compound. Suitable thickeners are well known in lubricating grease technology. In accordance with the present invention there is further provided a method for lubricating a constant velocity joint comprising packing it with lubricating grease according to the present invention. In accordance with the present invention there is further provided a constant speed gasket packed with a lubricating grease according to the present invention. Preferably, the constant velocity joint is generally a mobile constant velocity joint but may include, for example, universal joints for high speed, which may include fixed or moving types of constant velocity joints, or Hooke type universal joint. The molybdenum dithiocarbamates (MoDTC) used in the additive packages are frequently insoluble in oil, possibly present in the fats as a finely dispersed solid. However, dispersed solid additives can be separated from a fat during use. This effect has been experienced in fats containing solid additives in some severe trials of high temperature / high speed CVJ. This potential problem of centrifugation of solids from fats is particularly serious in universal joints incorporated in high speed drive shaft (HSPS) applications, where very high rotation speeds (approximately 4-6000 rpm) are common. Fats that use containers of additives soluble in all types of oil should not suffer from this problem. High levels of molybdenum and sulfur are usually required to provide a good reduction in friction. However, high levels of molybdenum and sulfur increase the insolubility of the composition. Another aspect of the present invention is, for - In ¬ Accordingly, the provision of a lubricating composition comprising a base oil and an oil-soluble friction reducing additive package comprising a combination of molybdenum dithiocarbamate, zinc naphthenate and one or more metal dithiophosphates. The use of a container for low friction soluble in all types of oil allows the development of grease for CVJ for high speed applications, without the risk of centrifugation and separation of solid additives. Furthermore, in the mobile constant speed gasket grease applications, such use makes possible the use of rigid greases, which maintain adequate rigidity during use and yet still provide a high lubricating penetrating power. The use of an efficient and soluble low friction container in all types of oil allows the development of universal joint greases in applications of high speed propulsion shafts. It can also be used in lubricant compositions for mobile joint applications, thus producing greases for constant speed joints that have a high lubrication penetration power. Optionally, they can be incorporated into the additive container - lf one or more other metal dithiocarbamates. In addition, the additive may include components not soluble in oil. It is preferred to use the combination of friction reducing additives in a lubricating grease comprising a base oil and a thickener, which preferably is a lithium soap, lithium complex, or a urea compound. Preferably, such a lubricating grease independently contains components of the type and in the amounts (preferably relative amounts) established with respect to the preferred characteristics of the first aspect of the invention. The present invention will now be described with reference to the following examples.

Examples Additives and base grease Table 1 lists some of the key compounds of molybdenum dithiocarbamate (MoDTC) that can be obtained commercially. The two MoDTC compounds with a high molybdenum content (MoDTC (3) and MoDTC (4)) are solid and mostly insoluble in oil. Other additives used in the examples are: ZnDTP (1) mainly zinc dithiophosphate (ZnDTP); largely isobutyl ZnDTP ZnDTP (2) an 85% solution, largely isobutyl ZnDTP in mineral oil ZnNa (1) solution of zinc naphthenate (8% zinc); containing approximately 60% zinc naphthenate in mineral oil Phosphate / thiophosphates Mixed amine phosphate / thiophosphates, amine in a 50% dilution, by weight, in mineral oil Sulfurized olefin Highly sulfided olefin (43% sulfur) ZnDTC Diamildithiocarbamate of zinc (6% zinc) The analysis was carried out largely including the additives in a fully formulated polyurea fat (PUG). The additive package has also been included in the base greases thickened with lithium soap and lithium complex, and in a semisynthetic diurea grease. The details of fats are given in the footnotes of the relevant tables.

Measurement of coefficient of friction and wear For all friction and wear measurements an oscillating SRV apparatus was used for friction tests, with a 10 mm sphere on a flat polished surface as the test geometry. The coefficients of friction were recorded after two hours of operation under fixed test conditions. The fixed test conditions were a load of 300 Newtons, an oscillation frequency of 50 Hertz, a path of 1.5 mm. and a temperature set at 100 ° C. The wear was evaluated by measuring the diameter of the wear mark on the sphere at the end of each two-hour period, using an optical grid.

The results are set forth in Tables 2-13. Development of a formulation based on MoDTC, soluble in oil.

Examples 1-5 Comparison between MoDTC (2) and MoDTC (1) To provide a baseline for comparison, the coefficients of friction measured in various commercial fats are summarized in Table 2 (Examples 1-5), Reference Fats (RG) Examples 8-39 The friction behavior of the MoDTC (2) and MoDTC (1) in combination with the ZnDTP was compared in the PUG fat (Table 3, Examples 8-11).

The coefficients of friction are usually high (compare RG in Table 2). For the 4% combination of MoDTC (1) /1.5% of ZnDTP (2) '(Example 11), a lower coefficient of friction was registered than that of the equivalent MoDTC (2) formulation (Example 10), but the coefficient was rose toward the end of the trial.

Combinations of additives with MoDTC (2) in PUG The proportions of ZnDTP and MoDTC used in Table 3 were chosen arbitrarily and it should be understood that these levels are not likely to be optimal for low friction. In order to establish the minimum coefficient of friction that can be achieved with this combination, the content ratio of ZnDTP (2) was varied from 0% to 50% (Examples of Table 4). The use of MoDTC (2) only produces coefficients of friction that are too low, although these are still clearly above those of the GR (Table 2). Table 5 shows that the use of an alternative zinc additive, ZnNa (1) in combination with MoDTC (2) does not produce low friction. Table 6 shows the effect and wear by varying the proportions of MoDTC (2), ZnNa (1) and ZnDTP (2) in a mixture of additives containing the three additives. The coefficient of friction and wear are dependent on the proportions of these three additives. Optimal levels were further studied by keeping the proportions of ZnNa (1): ZnDTP (2) constant at 2: 1, while the MoDTC level (2) was varied from 0% to 12% (Table 7). Tables 6 and 7 show that both friction and wear go through a minimum when the proportions of MoDTC (2), ZnNa (1) and ZnDTP (2) are approximately 4: 2: 1. Table 8 shows the effect of varying the total level of the additive package between 3.5% and 14%.

Effect of incorporating MoDTC (3) into the optimized package Table 9 shows that MoDTC (3) can be added to the new additive package without loss of friction performance. This was also found in formulating example 39 in a very different base fluid. 1.3% of MoDTC (3) contains essentially the same level of elemental molybdenum in the form of 8% MoDTC (2). The MoDTC (2) seems to be more effective than the MoDTC (3) for the same amount of molybdenum.

Effect on friction of inclusion of low cost extreme pressure additives It is possible that an extreme pressure additive can improve durability in the most severe applications of CVJ. To test the tolerance of such additives, both 1.5% sulfurized olefin and 1.5% amine phosphate / thiophosphates have been added to the PUG containing the container at the 7% level (4% MoDTC (2)).

Inclusion of the new container in base greases with lithium soap and lithium complex All the optimization work described above was carried out in PUG. To show the applicability of the additive package to other types of grease thickeners, the three additives MoDTC (2), ZnNa (l) and ZnDTP (2) of the new additive package were included in both a base grease with lithium soap and in a base grease with lithium complex (Table 11). In this table, detailed descriptions of both fats are given.

Example 39 Table 12 shows that the additive package can be included in a polyurea grease with a composition very different from the base oil, without loss of performance in terms of friction and wear. The MoDTC (3) is itself an additive with useful properties in terms of extreme pressure and it can also be seen from this table that the inclusion of the MoDTC (3) does not adversely affect the behavior of the friction fat SRV and wear. As indicated above, the fat formulations of the present invention may further comprise one or more additives that impart certain desirable characteristics to the formulations. In particular, other extreme pressure / antiwear agents may be included, such as borates, substituted thiadiazoles, polymeric nitrogen / phosphorus compounds, amine phosphates, sulfur esters and triphenyl phosphorothionate.

ZnDTC For comparison, the coefficient of friction was measured from a composition containing 3%, by weight, of zinc dithiocarbamate, 1.5%, by weight, of zinc dithiophosphate (ZnDTP (2)) and 2%, by weight, of zinc naphthenate (ZnNa (l)) in a polyurea-based fat that also contains 0.5%, by weight, of antioxidant. The composition had a coefficient of friction of 0.122. Table 1 Physical and chemical characteristics of some organomolybdenum compounds that may be commercially available.

Table 2 SRV friction behavior of several commercial greases (RG) for mobile joints Table 3 Comparison between friction behavior of the MoDTC (2) and MoDTC (1) in mixture with ZnDTP (2) in the PUG Composition of the PUG thickener base grease: 4.4 'bis (stearylureido) diphenylmethane (12%) Additives: 0.5% diphenylamine, 0.1% sulfurized olefin, 1.0% barium sulfonate base oil: HVI 160B: HVI 650 3: 1 ZnDTP (2) Table 4 Effect of adding ZnDTP (2) to 8% of MoDTC (2) in the PUG Table 5 Effect of gradually adding ZnNa (1 of MoDTC (2) in the PUG Table 6 Effect of varying the level of ZnDTP (2) and ZnNa (1) in a mixture of additives MoDTC (2) / ZnDTP (2) / ZnNa (1) in the PUG.

Table 7 Effect of gradually adding MoDTC (2) to a 2: 1 ratio of ZnNa (l) and ZnDTP (2) in the PUG Table 8 Effect of varying the total level of additives in the package MoDTC (2): ZnNa (1): ZnDTP (2) in the PUG Table 9 Friction coefficients of experimental formulations of fat in base fat with polyurea 27 32 31 Package of additives (% mass) MoDTC (3). - 1.3 1.3 MoDTC (2) 8, 0 - 8.0 ZnDTP (2) 2.0 2.0 2.0 ZnNa (1) 4.0 4.0 4.0 Molybdenum content (mass%) 0.39 0.36 0.75 SRV friction 0.058 0.073 0.056 Diameter of wear mark 0 0..4466 0.51 0.46 (mm) Table 10 Effect of adding additives for extreme pressure to the new container in the PUG Table 11 Effect of adding the new additive package to a base grease with lithium soap and lithium complex Base grease with lithium soap Thickener: 9.15% hydrogenated castor oil, 1.12% LH0H.H20 Comp. base oil: MVIN 170 (80%), HVI 170 (5%) HVI 105 (15%) Additive container 0.5% diphenylamine Base grease with lithium complex Additive container: 2% Vulkanox HS, 1% Irganox L101 Compos. Base oil: 50% HVI-160B, 50% HVI 650 Comp. thickener (parts): 7.7% of hydrogenated castor oil fatty acid 2.2% boric acid 2.6% LYOH.H20 1.5% calcium alkylsalicylate 1.5% calcium octoate Table 12 SRV friction without (Example 38 and with (Example 39; MoDTC (3) added in the PUG 38 39 Additive container (% mass) Barium sulfonate 1.0 1.0 ZnDTP (1) 1.0 1.0 ZnNa (1) 2.0 2.0 MoDTC (2) 4.0 4.0 MoDTC (3) _ 2.0 Base oil composition: 60% XHVI 5.2; 30% of HVI 60 10% of MVIN 70 Antioxidant: diphenylamine Friction SRV Coefficient of friction _ _ __ 0.050 0.053 Diameter of the wear mark (mm) 0.40 0.48 Table 13 Friction coefficients of experimental formulations of fat with MoDTC (3) in the PUG Example Example Example Example Example Example 41 42 43 44 45 46 Mass key additives) MoDTC (3) 3.0 3.0 3.0 3.0 3.0 3.0 ZnDTP (2) 1.5 1.5 1.5 1.5 1.5 ZnNa (1) - 2.0 - 1.0 2.0 ZnDTC - - 1.5 1.5 1.5 Friction SRV 0.138 .065 0.053 0.075 0.053 0.050 Composition of the base oil: "75% HVI 160B 25% HVI 650 Antioxidant 0.5% It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property.

Claims (10)

1. A lubricant composition, characterized in comprising a base oil in combination with molybdenum dithiocarbamate, zinc naphthenate and one or more metal dithiophosphates, and optionally one or more other metal dithiocarbamates.

2. A lubricating grease, characterized in that it comprises a thickener in combination with a lubricant composition according to claim 1.

3. A lubricating grease according to claim 2, characterized in that the ratio between molybdenum in molybdenum dithiocarbamate and total metal dithiophosphate ranges from 2: 1 to 1:20. and the ratio between the metallic dithiophosphate and the amount of zinc naphthenate varies from 0.85: 10 to 0.85: 0.05. and the relationship between molybdenum in molybdenum dithiocarbamate and zinc in zinc naphthenate ranges from 15: 1 to 1: 4.

4. A lubricating grease according to claim 2, characterized in that it contains molybdenum dithiocarbamate molybdenum in the amount of 0.04 to 2.5%, by weight.

5. A lubricating grease according to claim 2, characterized by containing zinc naphthenate in the amount of 0.05 to 12.0%, by weight.

6. A lubricating grease according to claim 2, 4 or 5, characterized in that said one or more metal dithiophosphates are present in the total amount of 0.1 to 10%, by weight.

7. A lubricating grease according to any of claims 2 to 6, characterized in that the thickener comprises a urea compound.

8. A method for lubricating a constant velocity joint, characterized in that it comprises packing it with a lubricating grease according to any of claims 2 to 7.

9. A constant velocity joint, characterized in that it is packaged with a lubricating grease according to any of claims 2 to 8.

10. A lubricant composition, characterized in that it comprises a base oil and a container of oil-soluble friction reducing additives comprising a combination of molybdenum dithiocarbamate, zinc naphthenate and one or more metal dithiophosphates.