FR3009309A1 - LUBRICATING COMPOSITIONS FOR TRANSMISSIONS - Google Patents

Abstract

The present invention relates to a lubricating composition comprising at least one base oil, at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group, at least one compound comprising a dithiophosphate group and at least one compound comprising a thiadiazole group. . The lubricant composition simultaneously has good anti-wear, extreme-pressure properties, a low coefficient of friction and good anti-seizure properties. The lubricant composition is useful for lubricating transmissions such as gearboxes, axles, preferably manual transmissions of motor vehicles.

Description

TECHNICAL FIELD The present invention is applicable to the field of lubricants, and more particularly to the field of lubricants for motor vehicles, in particular in the field of lubricants for transmission members of motor vehicles, in particular for manual gearboxes, decks or axles. double clutches. The invention relates to a lubricating composition comprising the combination of phosphorus, sulfur and phospho-sulfur compounds with an anticorrosive agent, as well as a process for their preparation. The lubricant composition according to the invention has in particular good extreme-pressure, anti-wear properties, and more particularly against the synchronizers present in the gearboxes, as well as a low coefficient of friction. The present invention also relates to a method of reducing the wear of a mechanical part employing this lubricant composition. The present invention also relates to a method of reducing seizure of a mechanical part employing this lubricant composition.

The present invention also relates to a method for reducing the peeling of a mechanical part employing this lubricating composition. The present invention also relates to a concentrated additive type composition comprising the combination of phosphorus, sulfur and phospho-sulfur compounds with an anti-corrosion agent.

TECHNOLOGICAL BACKGROUND It is very difficult to formulate lubricating compositions which simultaneously have good extreme-pressure properties, good anti-wear properties and good friction properties, as well as good anti-seizure properties. Thus, most lubricating compositions exhibit only two of these properties. Moreover, despite the existence of many anti-wear additives, extreme pressure additives or friction modifying additives, all do not have the same effectiveness, some may improve a property and at the same time damage a second property. Similarly, the chemistry of these additives is complex and the additives can react with each other to form new chemical species whose influence on extreme-pressure, wear, friction and galling properties is not known at the end.

It is known that additives such as diphosphites, which may be both friction modifiers and anti-wear components, react with the sulfur atoms contained in the extreme pressure additives to form thiophosphonic derivatives for example, whose properties are significantly different from those of the original molecules.

Thus, many extreme-pressure components react with anti-wear additives or friction modifiers to give new chemical entities. These reactions are not controlled and the exact properties of the final product are also not mastered over time. Interactions can occur between the various extreme-pressure / anti-wear / friction modifier additives and lead to antagonistic effects on the final properties of the additive compositions. US 2009/011964, US 5674820 and US 5872085 describe a lubricating composition comprising a compound comprising a dithiocarbamate group, a compound comprising a phosphite group and a compound comprising a dithiophosphate group. However, the presence of a compound comprising a dithiophosphate group is likely to cause significant wear of the synchronizers. Moreover, these documents do not describe the presence of a thiadiazole compound. The wear of synchronizers present in a gearbox, and more particularly in manual gearboxes, is a major and recurring problem. This type of wear in particular involves contacts other than steel / steel contacts, such as steel / brass contacts. Lubricating compositions making it possible to reduce the wear of the synchronizers have been described.

Thus WO 03/035810 discloses a lubricating composition comprising a base oil, an amino salt of a phosphorus-containing acid, a metal salt of an organic acid. In addition, the lubricating composition may further comprise a metal deactivator compound, which may be a dimercaptothiadiazole compound and a boron dispersant. However, this document does not disclose the presence of compounds comprising a dithiocarbamate group or compounds comprising a dithiophosphate group. In addition, the lubricating composition described in this document must comprise less than 0.1% by weight of non-metallic and sulfur-containing anti-wear / extreme pressure compounds, which may correspond to compounds comprising a dithiocarbamate group or to compounds comprising a dithiophosphate group.

It would therefore be desirable to have a lubricating composition, especially for motor vehicles, which simultaneously has good extreme pressure, friction and anti-wear properties, especially against synchronizers, as well as good anti-seizing properties. . It would also be desirable to have a lubricating composition, especially for motor vehicles, which is both stable and has good extreme pressure, friction, anti-wear and anti-seizing properties. It would also be desirable to have a lubricating composition, especially for motor vehicles which limits the risk of chipping and which has good extreme-pressure, friction, anti-wear and anti-seizing properties. An object of the present invention is to provide a lubricant composition overcoming all or in part the aforementioned drawbacks. Another object of the invention is to provide a lubricating composition which is stable and easy to implement.

Another object of the invention is to provide a lubrication method that notably makes it possible to reduce the wear of the synchronizers in the gearboxes. SUMMARY OF THE INVENTION The subject of the invention is thus a lubricating composition comprising: at least one at least one base oil, at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group, and - at least one compound D comprising a thiadiazole group, the compound A comprising a dithiocarbamate group being a mixture of: at least one amine dithiocarbamate of general formula (I) ( Compound A-1) in which - R 1 and R 2 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 5 carbon atoms; 30 carbon atoms, - R3, R4 and R5 represent independently of one another a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of the groups R3, R4 and R5 is not a hydrogen atom and at least one metal dithiocarbamate of general formula (II) (compound A-2), wherein R6 and R7 are independently of one another hydrocarbon compounds, optionally substituted, comprising from 1 to 25 carbon atoms, M represents a metal cation and n is the valence of this metal cation, - the ratio by weight (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1:10. Surprisingly, the Applicant has found that the presence of at least one compound comprising a dithiophosphate group, of at least one compound comprising a phosphite group, of at least one compound comprising a dithiocarbamate group in the form of a Specific mixture of a compound of formula (I) and a compound of formula (II) and at least one compound comprising a thiadiazole group in a lubricating composition enables the lubricating composition to be imparted simultaneously with excellent properties. 35117 EN R2 20 ln mn + pressure, friction and anti-wear, especially against synchronizers, as well as good anti-seizing properties. Thus, the present invention makes it possible to formulate lubricating compositions comprising a reduced content of compounds comprising a dithiophosphate group and yet having outstanding extreme-pressure, friction, anti-wear and anti-seizing properties. Advantageously, the lubricant compositions according to the invention have improved anti-wear properties against the synchronizers present in the gearboxes.

Advantageously, the lubricant compositions according to the invention also have good anti-peeling properties. Advantageously, the lubricant compositions according to the invention also have good antioxidant and anti-corrosion properties. Advantageously, the lubricant compositions according to the invention have improved storage stability and a viscosity that does not vary or is very little. In one embodiment of the invention, the lubricant composition consists essentially of: at least one at least one base oil, at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group, and - at least one compound D comprising a thiadiazole group, the compound A comprising a dithiocarbamate group being a mixture of: at least one amine dithiocarbamate of general formula (I) ( wherein R1 and R2 independently of one another are optionally substituted hydrocarbon groups having from 1 to 30 carbon atoms, R3, R4 and R5 represent, independently of one another, a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of the groups R3, R4 and R5 is not a hydrogen atom, and - d at least one metal dithiocarbamate of the general formula (II) (compound A-2), wherein R6 and R7 are, independently of each other, optionally substituted hydrocarbon groups, comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation, - the weight ratio (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1:10 The invention also relates to a process for the preparation of a lubricating composition as defined above. The invention also relates to a transmission oil comprising a lubricating composition as defined above. The invention also relates to the use of a lubricant composition as defined above for the lubrication of transmissions such as gearboxes or bridges, preferably motor vehicle gearboxes, advantageously for the lubrication of the boxes. manual speeds. The invention also relates to the use of a lubricant composition according to the invention for reducing the fuel consumption of vehicles, in particular motor vehicles. The invention also relates to the use of a lubricant composition according to the invention for reducing the seizure of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a gearbox. manual gear. The invention also relates to the use of a lubricant composition according to the invention for reducing the wear of a gearbox synchronizer, preferably of manual gearboxes. The invention also relates to the use of a lubricant composition according to the invention for reducing the peeling of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a box. manual gear. The invention also relates to a method for lubricating transmissions such as gearboxes, bridges, preferably manual gearboxes of motor vehicles, said method comprising at least one step of contacting the lubricant composition according to the invention. invention. The invention also relates to a method for reducing the seizure of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox, comprising at least contacting. of the mechanical part with a lubricating composition according to the invention. The invention also relates to a method for reducing the wear of a gearbox synchronizer, preferably of manual gearboxes, comprising at least putting the synchronizer into contact with a lubricant composition according to the invention. The invention also relates to a method for reducing the peeling of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox, comprising at least the setting in contact with the mechanical part with a lubricating composition according to the invention. The invention also relates to the use of at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group and at least one compound D comprising a thiadiazole group in a base oil for improving the anti-wear, extreme-pressure, friction and anti-seizing properties of a lubricating composition, wherein the compound A comprising a dithiocarbamate group is a mixture of: - at least one amine dithiocarbamate of general formula (I) (compound A-1) wherein R1 and R2 independently represent one of the compounds of formula (I); other optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms; - R3, R4 and R5 represent, independently of one another, a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, with the understanding that at least one of R3, R4 and R5 is not a hydrogen atom, and at least one metal dithiocarbamate of general formula (II) (compound A-2), / S 1 1 RC and 6 NS Mn + wherein R6 and R7 are, independently of each other, optionally substituted hydrocarbon groups having 1 to 30 carbon atoms, M is a metal cation and n is the valency of said metal cation. The invention also relates to a composition of additive concentrate type comprising: at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group, and at least one compound D comprising a thiadiazole group. Detailed Description of the Invention The percentages given below correspond to percentages by weight of active ingredient. Dithiocarbamate The lubricating composition according to the invention comprises at least one compound A comprising a metal dithiocarbamate group and at least one compound comprising an amine dithiocarbamate group. For the sake of simplification of the description, the compound comprising a metal dithiocarbamate group is called "metal dithiocarbamate" and the compound comprising an amine dithiocarbamate is called "amine dithiocarbamate" in the following description. The metal dithiocarbamate is a metal dithiocarbamate of general formula (II) (compound A-2), in which R6 and R7 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation: ## STR1 ## Preferably, the metal is selected from the group consisting of zinc, aluminum, copper, iron, mercury, carbon, silver, cadmium, tin, lead, antimony, bismuth, thallium, chromium, molybdenum, cobalt, nickel, tungsten, sodium, calcium, magnesium, manganese and arsenic. In a preferred embodiment of the invention, the metal is selected from zinc, molybdenum and antimony, preferably zinc and molybdenum, preferably zinc. Mixtures of metals can be used. The metal dithiocarbamates are neutral as shown in formula (II) or basic when a stoichiometric excess of metal is present. Preferably, R6 and R7 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferably from 4 to 20 carbon atoms. 12 carbon atoms. In a preferred embodiment of the invention, R6 and R7 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl groups. . The alkyl, alkenyl, alkynyl and aryl groups comprise from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferentially from 4 to 12 carbon atoms.

In another preferred embodiment of the invention, R6 and R7 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably preferably 3 to 18 carbon atoms, more preferably 4 to 12 carbon atoms. In another preferred embodiment of the invention, R6 and R7 independently of one another represent hydrocarbon groups optionally substituted with one or more heteroatoms such as the oxygen atom, the nitrogen atom, the sulfur atom, the phosphorus atom, preferably with one or more oxygen atoms. Useful metal dithiocarbamates are compounds well known to those skilled in the art. One of the processes for the preparation of these compounds is described in US Pat. No. 249,223. Suppliers of such additives are, for example, Vanderbilt, Rhein Chemie, Adeka and King Industries.

Commercial compounds are, for example, Vanlube® AZ, Vanlube® EZ, Vanlube® 73, Vanlube® 73 Super Plus, Molyvan® A, Molyvan® 807, Molyvan® 822, Additin® RC 6301, Additin® RC 6320, Sakura-Lube® 200, Sakura-Lube® 165, Sakura-Lube® 525, Sakura-Lube® 600, Na-Lube® ADTC. These compounds are marketed in particular by one of the suppliers mentioned above. In a preferred embodiment of the invention, the metal dithiocarbamate is a zinc dithiocarbamate of formula (II-a), in which R6 and R7 have the same meaning as in formula (II): 35117 FR SS R6 / R N1, Zn; Particularly preferred compounds having the formula (II-a) are such that R6 and R7 independently of one another are linear alkyl hydrocarbon groups having from 4 to 12 carbon atoms and are for example, zinc diamyldithiocarbamate and zinc dibutyldithiocarbamate. In another preferred embodiment of the invention, the metal dithiocarbamate is a molybdenum dithiocarbamate of formula (II-b), wherein R6 and R7 have the same meaning as in formula (II): ## STR2 ## Embedded image The amine dithiocarbamate is an amine dithiocarbamate of the general formula (I), in which R 1 and R 2 represent independently of each other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R3, R4 and R5 independently of one another represent a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of the groups R3, R4 and R5 is not a hydrogen atom: ## STR2 ## In a preferred embodiment of the invention R1 and R2 independently of one another are optionally substituted hydrocarbon groups having from 2 to 24 carbon atoms; rbone, more preferably from 3 to 18 carbon atoms, more preferably from 4 to 12 carbon atoms. In another preferred embodiment of the invention, R 1 and R 2 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. These alkyl, alkenyl, alkynyl and aryl groups comprise from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferentially from 4 to 12 carbon atoms.

In another preferred embodiment of the invention, R 1 and R 2 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, more preferably from 4 to 12 carbon atoms. In another preferred embodiment of the invention, R1 and R2 independently of one another represent hydrocarbon groups optionally substituted with one or more heteroatoms such as the oxygen atom, the nitrogen atom, the sulfur atom, the phosphorus atom, preferably with one or more oxygen atoms. In another preferred embodiment of the invention, R 3, R 4 and R 5 represent, independently of one another, a hydrocarbon group comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, and even more preferably from 4 to 12 carbon atoms.

Particularly preferred compounds are diamyl amine diamyldithiocarbamate and diamyl amine dibutyldithiocarbamate. Commercial compounds are, for example, Vanlube® EZ marketed by Vanderbilt. In a more preferred embodiment of the invention, the dithiocarbamate is a mixture of at least one amine dithiocarbamate of general formula (I) and at least one metal dithiocarbamate of general formula (II-a) described herein. -above. Advantageously, the dithiocarbamate is a mixture of zinc dithiocarbamate and diamylammonium diamyldithiocarbamate.

In one embodiment, the composition according to the invention may further comprise another compound comprising a dithiocarbamate group other than a dithiocarbamate of formula (I) or a dithiocarbamate of formula (II). In a preferred embodiment of the invention, this other compound comprising a dithiocarbamate group is chosen from the group consisting of bisdithiocarbamates, ammonium dithiocarbamates and ester dithiocarbamates, taken alone or as a mixture. In a first embodiment, this other dithiocarbamate compound is a bisdithiocarbamate of general formula (VI-a), in which R29, R30, R31 and R32 represent, independently of one another, optionally substituted hydrocarbon groups comprising 1 to 30 carbon atoms, R33 represents a hydrocarbon group of 1 to 8 carbon atoms: ## STR1 ## In a preferred embodiment of the invention, R 29, R 30, R 31 and R 32 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferably from 5 to 12 carbon atoms; . In another preferred embodiment of the invention, R29, R30, R31 and R32 independently of one another represent unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl groups. preferably phenyl or benzyl. In another preferred embodiment of the invention, R29, R30, R31 and R32 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 29, R 30, R 31 and R 32 represent, independently of one another, hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and or phosphorus, preferably one or more oxygen atoms. In another preferred embodiment of the invention, R33 represents a hydrocarbon group of 2 to 6 carbon atoms. Commercial compounds are, for example, Vanlube® 7723 sold by Vanderbilt or Additin® RC 6340 sold by Rhein Chemie. In a second embodiment, this other dithiocarbamate compound is an ammonium dithiocarbamate of general formula (VI-b), in which R34 and R35 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to at 30 carbon atoms: In a preferred embodiment of the invention, R34 and R35 represent, independently of one another, optionally substituted hydrocarbon groups comprising 2 to 24 carbon atoms, more preferably 3 to 18 carbon atoms, even more preferably 5 to 12 carbon atoms. In another preferred embodiment of the invention, R 34 and R 35 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. In another preferred embodiment of the invention, R34 and R35 represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

In another preferred embodiment of the invention, R34 and R35 represent, independently of one another, hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms. In a third embodiment, this other dithiocarbamate compound is an ester dithiocarbamate of the general formula (VI-c), in which R 36 and R 37 independently of one another are optionally substituted hydrocarbon groups, comprising from 1 to 30 carbon atoms, R38 and R39 are, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms: R36 S-R38-C-OR39 R37 (VI-c) preferred embodiment of the invention, R36 and R37 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferably from 5 to 12 carbon atoms.

In another preferred embodiment of the invention, R 36 and R 37 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. In another preferred embodiment of the invention, R 36 and R 37 represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 36 and R 37 represent, independently of one another, hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms. In another preferred embodiment of the invention, R38 and R39 represent, independently of one another, hydrocarbon groups of 2 to 6 carbon atoms.

In one embodiment of the invention, the lubricating composition comprises from 0.1 to 5% by weight of compounds A comprising a dithiocarbamate group, relative to the total mass of lubricating composition, preferably from 0.2 to 4% more preferably from 0.3 to 2%, advantageously from 0.5 to 1%.

In another embodiment of the invention, the lubricating composition comprises from 0.1 to 3% by weight of the mixture of amine dithiocarbamate 35117 FR corresponding to formula (I) (compound A-1) and metal dithiocarbamate compound of formula (II) (compound A-2), preferably from 0.1 to 2% by weight, preferably from 0.5 to 2% by weight, based on the total weight of the lubricating composition.

Phosphite The lubricating composition according to the invention comprises at least one compound B comprising a phosphite group. For the sake of simplification of the description, the compound B comprising a phosphite group is called "phosphite" in the following description. In one embodiment of the invention, the phosphite is chosen from phosphite monoesters, phosphite diesters or phosphite triesters, taken alone or as a mixture. Phosphite monoesters are found in two equilibrium forms, a "ketone" form and an "alcohol" form. It is the same for phosphite diesters. In one embodiment of the invention, the phosphite may be a phosphite monoester of general formula (III-a) in its alcohol and / or ketone form, wherein R8 represents an optionally substituted hydrocarbon group comprising from 1 to 30 carbon atoms: HO 0 0 0 .... * .......... -... P R8 PH R8 1 1 OH OH form alcohol form ketone (III- a) In a preferred embodiment of the invention, R8 represents an optionally substituted hydrocarbon group comprising from 2 to 24 carbon atoms, more preferably from 3 to 20 carbon atoms, even more preferably from 4 to 18 carbon atoms. carbon, more preferably 6 to 16 carbon atoms, more preferably 8 to 15 carbon atoms. In another preferred embodiment of the invention, R8 represents an unsubstituted hydrocarbon group, said hydrocarbon group possibly being an alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl group. In another preferred embodiment of the invention, R8 represents a linear or branched alkyl hydrocarbon group, more preferably a linear alkyl hydrocarbon group. In another preferred embodiment of the invention, R8 represents a hydrocarbon group substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably oxygen atoms. In another embodiment of the invention, the phosphite may also be a phosphite diester of general formula (III-b) in its alcohol and / or ketone form, wherein R9 and R10 independently represent one of the other hydrocarbon groups, optionally substituted, of 1 to 30 carbon atoms: HO 0 0 0 P R9 PH R9 1 1 0 0 Rio form alcohol form ketone (III-b) In a preferred embodiment of the invention, R9 and R 10 represent hydrocarbon groups, optionally substituted, comprising from 2 to 24 carbon atoms, more preferably from 3 to 20 carbon atoms, even more preferably from 4 to 18 carbon atoms, even more preferably from 6 to 16 carbon atoms. more preferably 8 to 12 carbon atoms. In another preferred embodiment of the invention, R 9 and R 10 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. In another preferred embodiment of the invention, R 9 and R 10 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 9 and R 10 represent hydrocarbon groups substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably with one or more carbon atoms. oxygen. As examples of phosphite diesters, mention may be made of dimethyl phosphite, diethyl phosphite, diisopropyl phosphite, dibutyl phosphite, dihexyl phosphite, dicylohexyl phosphite, diisodecyl phosphite, di-n-octyl phosphite, dibenzyl phosphite, diphenyl phosphite or dioleyl phosphite.

In one embodiment of the invention, the phosphite may also be a phosphite triester of general formula (II lc) in which R 11, R 12 and R 13 represent, independently of one another, optionally substituted hydrocarbon groups, comprising from 1 to 30 carbon atoms: ## STR2 ## In a preferred embodiment of the invention, R 11, R 12 and R 13 represent optionally substituted hydrocarbon groups comprising from 2 to 24 atoms. carbon, more preferably 3 to 20 carbon atoms, still more preferably 4 to 18 carbon atoms, even more preferably 6 to 16 carbon atoms, even more preferably 8 to 12 carbon atoms. In another preferred embodiment of the invention, R 11, R 12 and R 13 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl or aryl groups, preferably phenyls or benzyls.

In another preferred embodiment of the invention, R 11, R 12 and R 13 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 11, R 12 and R 13 represent hydrocarbon groups substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably one or more carbon atoms. 'oxygen. Examples of phosphite triesters which may be mentioned are diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, tridimethylphenyl phosphite, diphenyl ethylhexyl phosphite, phenyl diisodecyl phosphite, triisodecyl phosphite, trilauryl phosphite, triphenyl phosphite, tris (dipropylene glycol) ) Phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris (5-norbornene-2-methyl) phosphite, tris (tridecyl) phosphite, trimethyl phosphite triethyl phosphite, triisopropyl phosphite, tributyl phosphite, triisoctyl phosphite, tribenzyl phosphite, triphenyl phosphite, poly (dipropylene glycol) phenyl phosphite or tris (dipropylene glycol) phosphite. Commercial compounds are, for example, Duraphos® AP230, Duraphos® AP240L, Duraphos® DBHP, Doverphos® 4, Doverphos® 10, Doverphos® 213, Doverphos® 6, Doverphos® 7, Doverphos® 8 , Doverphos® 9, Doverphos® 11, Doverphos® 12, Doverphos® 613, Doverphos® 675, Doverphos® 49, Doverphos® 53, Doverphos® 72, Doverphos® 253, Doverphos® 271 , Irgaphos® OPH, or Rhodaphos® range products marketed by Rhodia. In one embodiment of the invention, the lubricating composition comprises from 0.1 to 5% by weight of phosphite, relative to the total weight of the lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, even more preferably 0.5 to 1%. Dithiophosphate The lubricating composition according to the invention comprises at least one compound C comprising a dithiophosphate group. For the sake of simplification of the description, the compound C comprising a dithiophosphate group is called "dithiophosphate" in the following description. In one embodiment of the invention, the dithiophosphate may be selected from the group consisting of ammonium dithiophosphates, amine dithiophosphates, ester dithiophosphates and metal dithiophosphates, alone or in admixture. Ammonium dithiophosphates, amine dithiophosphates and ester dithiophosphates have the advantage of being dithiophosphate without ash and in particular without zinc. In a first embodiment, the dithiophosphate is an ammonium dithiophosphate of the general formula (IV-a), wherein R14 and R15 independently represent one of the other hydrocarbon groups, optionally substituted, comprising from 1 to 30 carbon atoms. In a preferred embodiment of the invention, R14 and R15 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, and more preferably from 5 to 12 carbon atoms. In another preferred embodiment of the invention, R14 and R15 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkenyl, alkynyl, aryl, preferably phenyl or benzyl groups. . In another preferred embodiment of the invention, R14 and R15 represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R14 and R15 represent, independently of one another, hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms. Examples of dithiophosphates that may be mentioned include ammonium dimethyl dithiophosphates, ammonium diethyl dithiophosphates or ammonium dibutyl dithiophosphates. In a second embodiment, the dithiophosphate is an amine dithiophosphate of the general formula (IV-b), in which R16 and R17 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R18, R19 and R20 represent, independently of one another, a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of the groups R18, R19 and R20 In a preferred embodiment of the invention, R16 and R17 independently represent one of the following groups: ## STR2 ## In a preferred embodiment of the invention, R.sup.16 and R.sub.17 independently represent one of the. other hydrocarbon groups, optionally substituted, comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferably from 5 to 12 carbon atoms. In another preferred embodiment of the invention, R16 and R17 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl.

In a preferred embodiment of the invention, R16 and R17 represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In a preferred embodiment of the invention, R16 and R17 independently of one another represent hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms. In a preferred embodiment of the invention, R18, R19 and R20 represent, independently of each other, a hydrocarbon group comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, even more preferentially from 5 to 12 carbon atoms. Commercial compounds are, for example, Additin® RC 3880 marketed by Rhein Chemie. In a third embodiment, the dithiophosphate is an ester dithiophosphate of the general formula (IV-c), in which R21 and R22 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R23 and R24 represent, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms: R21-0 II PS-R23 C OR24 R22-0 (IV-c) preferred embodiment of the invention, R21 and R22 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 35117 FR 18 carbon atoms, even more preferentially from 5 to 12 carbon atoms. In another preferred embodiment of the invention, R21 and R22 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. In another preferred embodiment of the invention, R21 and R22 represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 21 and R 22 represent, independently of one another, hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms.

In another preferred embodiment of the invention, R21 and R22 represent, independently of one another, a hydrocarbon group of 2 to 6 carbon atoms. In another preferred embodiment of the invention, R23 and R24 represent, independently of one another, hydrocarbon groups comprising from 2 to 6 carbon atoms. Commercial compounds are, for example, Irgalube® 63 marketed by BASF. In a fourth embodiment, the dithiophosphate is a metal dithiophosphate of general formula (IV-d), in which R 25 and R 26 represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms. carbon, M represents a metal cation and n is the valency of this metal cation: embedded image In a preferred embodiment of the invention, the metal is selected from the group consisting of: ## STR2 ## consisting of zinc, aluminum, copper, iron, mercury, silver, cadmium, tin, lead, antimony, bismuth, thallium, chromium, molybdenum, cobalt, nickel, tungsten, sodium, calcium, magnesium, manganese and arsenic. In a more preferred embodiment of the invention, the metal is selected from zinc, molybdenum, antimony, preferably zinc and molybdenum, preferably zinc. Mixtures of metals can be used. Metal dithiophosphates are neutral as exemplified in formula (IV-d) or basic when a stoichiometric excess of metal is present. In another preferred embodiment of the invention, R 25 and R 26 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, still more preferably from 5 to 12 carbon atoms. In another preferred embodiment of the invention, R 25 and R 26 represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, aryl, preferably phenyl or benzyl. In another preferred embodiment of the invention, R 25 and R 26 represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups. In another preferred embodiment of the invention, R 25 and R 26 independently of one another represent hydrocarbon groups optionally substituted with one or more oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably by one or more oxygen atoms. Useful metal dithiophosphates are compounds well known to those skilled in the art. Commercial compounds are, for example, Additin® RC 3038, Additin® RC 3045, Additin® RC 3048, Additin® RC 3058, Additin® RC 3080, Additin® RC 3180, Additin® RC 3212, Additin® RC 3580 marketed by Rhein Chemie, Kikulube® Z112 marketed by Adeka, Lubrizol® 1371, Lubrizol® 1375, Lubrizol® 1395, Lubrizol® 5179 marketed by Lubrizol company, Oloa® 260 or Oloa® 267 marketed by Oronite. In a preferred embodiment of the invention, the metal dithiophosphate is a molybdenum dithiophosphate of formula (IV-d-1), in which R25 and R26 have the same meaning as in formula (IV-d): 35117 EN In another preferred embodiment of the invention, dithiophosphate is also used in a further preferred embodiment of the invention. metal is a zinc dithiophosphate of formula (IV-d-2), wherein R25 and R26 have the same meaning as in formula (IV-d): ## STR2 ## (IV-d-2) In one embodiment of the invention, the lubricating composition comprises 0.1 to 5% by weight of dithiophosphate, based on the total weight of the lubricating composition, preferably 0, 2 to 4%, more preferably 0.3 to 2%, even more preferably 0.5 to 1%. Thiadiazole The lubricating composition according to the invention comprises at least one compound D comprising a thiadiazole group. For the sake of simplification of the description, the compound D comprising a thiadiazole group is called "thiadiazole" in the following description.

In one embodiment of the invention, the thiadiazole is a compound of formula (Va) -R28 in which: R27 and R28, which are identical or different, independently represent a hydrogen atom or a saturated or unsaturated alkyl group, linear or branched, comprising from 1 to 30 carbon atoms, - a represents an integer ranging from 1 to 3, - b represents an integer ranging from 1 to 3. In another embodiment of the invention, R27 and R28 represent a linear or branched, saturated or unsaturated alkyl group comprising from 1 to 20 carbon atoms, preferably from 1 to 15 carbon atoms, more preferably from 5 to 15 carbon atoms, advantageously from 10 to 15 atoms of carbon. In a preferred embodiment of the invention, R27 and R28 represent a saturated alkyl group, linear or branched, comprising 12 carbon atoms. In another preferred embodiment of the invention, a represents an integer equal to 1 or 2 and b represents an integer equal to 1 or 2.

In another embodiment of the invention, thiadiazole is a compound of formula (Vb) -R28 HN-N (Vb) in which: - R28 represents a hydrogen atom or an alkyl group, saturated or unsaturated, linear or branched, comprising from 1 to 30 carbon atoms, - b represents an integer ranging from 1 to 3. In another embodiment of the invention, R28 represents linear or branched, saturated or unsaturated alkyl group comprising 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 5 to 15 carbon atoms, preferably 10 to 15 carbon atoms. In a preferred embodiment of the invention, R28 represents a saturated alkyl group, linear or branched, comprising 12 carbon atoms.

In another preferred embodiment of the invention, b represents an integer of 1 or 2. In another preferred embodiment of the invention, the thiazole is a mixture of at least one compound of formula ( Va) and at least one compound of formula (Vb) as defined above.

In a more preferred embodiment of the invention, the thiazole is a mixture of: at least one compound of formula (Va) in which R27 and R28 represent a saturated, linear or branched alkyl group comprising 12 atoms; of carbon, a represents an integer equal to 1 or 2 and b represents an integer equal to 1 or 2; at least one compound of formula (Vb) in which R28 represents a saturated, linear or branched alkyl group comprising 12 carbon atoms and b represents an integer equal to 1 or 2. As an example of thiadiazole according to the invention can be made of RC 8210 sold by Rhein Chemie. In one embodiment of the invention, the lubricating composition comprises from 0.1 to 5% by weight of thiadiazole, relative to the total weight of the lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, even more preferably 0.5 to 1%. In another embodiment of the invention, the ratio by weight (compound comprising a dithiophosphate group: compound comprising a thiadiazole group) ranges from 3: 1 to 1: 8, preferably from 2: 1 to 1: 5, advantageously from 1: 1 to 1: 5 Base oil The lubricant compositions according to the invention may contain any type of mineral, synthetic or natural, animal or vegetable lubricating base oil adapted for their use. The base oil (s) used in the lubricant compositions according to the present invention may be oils of mineral or synthetic origin of groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) as summarized. below, alone or mixed. 35117 EN Table I Content of Content in Viscosity Index (VI) saturated sulfur Group I Oils <90%> 0.03% 80 VI <120 mineral Group II Oils> 90% 0.03% 80 VI <120 hydrocracked Group III Oils> _90% < _0.03% 120 hydrocracked or hydro-isomerized Group IV Polyalphaolefines (PAO) Group V Esters and other bases not included in bases groups I to IV The mineral base oils according to the invention include all types of bases obtained by atmospheric distillation and under empty crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking and hydroisomerization, hydrofinishing. The base oils of the lubricating compositions according to the invention may also be synthetic oils, such as certain carboxylic acid esters and alcohols, or polyalphaolefins. The polyalphaolefins used as base oils are, for example, obtained from monomers having from 4 to 32 carbon atoms (for example octene, decene), and a viscosity at 100 ° C. of between 1.5 and 15 cSt measured according to US Pat. ASTM D445 standard. Their weight average molecular weight is typically between 250 and 3000 measured according to ASTM D5296. Mixtures of synthetic and mineral oils can also be used. There is no limitation as to the use of a particular lubricating base for producing the lubricating compositions according to the invention, except that they must have properties, in particular viscosity, viscosity index, sulfur, oxidation resistance, suitable for use in a gearbox, in particular in a gearbox of motor vehicles, especially in a manual gearbox. In one embodiment of the invention, the lubricating bases represent at least 50% by weight, relative to the total mass of the lubricating composition, preferably at least 60%, or at least 70%. Typically, they represent between 75 and 99.9% by weight, relative to the total mass of the lubricating compositions according to the invention. In a preferred embodiment of the invention, the lubricating compositions comprise Group I and / or III mineral bases, or Group IV synthetic bases according to the API classification. In another preferred embodiment of the invention, the lubricating compositions have a kinematic viscosity at 100 ° C. measured according to ASTM D445 of between 4 and 41 cSt, according to classification SAE J 306, preferably between 4.1 and 32.5 cSt, advantageously from 6 to 18.5 cSt. Preferred grades are all grades from 75W to 140, including 75W, 75W80 and 75W90. In another preferred embodiment of the invention, the lubricating compositions have a viscosity index (VI) greater than 120 (ASTM 2270).

Other additives The lubricant compositions according to the invention may also contain any type of additive suitable for use in transmission oil formulations, for example one or more additives chosen from polymers, antioxidants, anti-corrosion additives, dispersants, present at the usual contents required for the application. The polymers are selected from the group of shear-stable polymers, preferably from the group consisting of copolymers of ethylene and alpha-olefin, polyacrylates such as polymethacrylates, copolymer olefins (OCP), ethylene propylene diene Monomers (EPDM), polybutenes, copolymers of styrene and olefin, hydrogenated or not, or copolymers of styrene and acrylate. The preferred polymers are polymethacrylates (PMA). In a preferred embodiment of the invention, the lubricating composition further comprises at least one dispersant. Preferred dispersants are polyisobutylenes (PIB) or polyisobutene derivatives. More preferably, the lubricant composition according to the invention may comprise a dispersant derived from polyisobutene. As an example of a polyisobutene derivative, there may be mentioned polyisobutylenes of succinic anhydride, amino derivatives of succinic anhydride polyisobutylenes (PIB succinimides). Preferred antioxidants are, for example, aminated antioxidants. More preferably, the lubricating composition according to the invention may comprise an antioxidant chosen from the group of aromatic amines, for example diphenylamines, in particular dialkylphenylamines, such as octadiphenylamines, phenyl-alpha-naphthyl amines. In another embodiment of the invention, the lubricating composition may comprise an antioxidant derived from phenol (dibutylhydroxytoluene BHT and derivatives) or a sulfur antioxidant (sulfurized phenates). In a preferred embodiment of the invention, the lubricant composition comprises an antioxidant selected from the group consisting of aromatic amines or phenol derivatives. The preferred anti-corrosion additives are phenolic derivatives, in particular ethoxylated phenol derivatives substituted with ortho-position alkyl groups.

In another preferred embodiment, the lubricating composition further comprises at least one dispersant and at least one other additive selected from those mentioned above. In one embodiment of the invention, the lubricating composition comprises: from 75 to 99.6% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group, of 0.1 at 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) such that described above and a metal dithiocarbamate of general formula (II) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group, the ratio by weight (compound C comprising a group dithiophosphate: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10.

In another embodiment of the invention, the lubricating composition comprises: 75 to 99.6% of a base oil, 0.1 to 5% of a compound B comprising a phosphite group, 0.1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I ) as described above and a metal dithiocarbamate of general formula (II-a) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group, the ratio by weight ( compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10.

In another embodiment of the invention, the lubricating composition comprises: from 75 to 99.1% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group, from 0, 1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) such as described above and a metal dithiocarbamate of general formula (II) as described above, from 0.1 to 5% of at least one compound D comprising a thiadiazole group, from 0.5 to 3% of at least one other additive, the ratio by weight (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10. In another embodiment of the invention, the lubricating composition comprises: from 75 to 99.1% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group, 35117 FR of 0.1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) such as as described above and a metal dithiocarbamate of general formula (II-a) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group, from 0.5 to 3% of another additive, the weight ratio (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10. In another embodiment of the invention, the lubricating composition consists essentially of: 75 to 99.6% of a base oil, 0.1 to 5% of a compound B comprising a phosphite group, 0.1 at 5% of a compound C comprising a dithiophosphate group, 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) as described above and a metal dithiocarbamate of general formula (II) as described above, - 0.1 to 5% of a compound D comprising a thiadiazole group, - the ratio by weight (compound C comprising a grouping dithiophosphate: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10. In another embodiment of the invention, the lubricating composition consists essentially of: from 75 to 99.6% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group from 0.1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) as described above and a metal dithiocarbamate 35117 FR of general formula (II-a) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group the ratio by weight (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10. In one embodiment of the invention, the lubricating composition consists essentially of: from 75 to 99.1% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group, from 0 to 1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) as described above and a metal dithiocarbamate of general formula (II) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group, from 0.5 to 3% d another additive, the weight ratio (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10.

In one embodiment of the invention, the lubricating composition consists essentially of: from 75 to 99.1% of a base oil, from 0.1 to 5% of a compound B comprising a phosphite group, from 0 to 1 to 5% of a compound C comprising a dithiophosphate group, from 0.1 to 5% of a compound A comprising a dithiocarbamate group, this compound being a mixture of an amine dithiocarbamate of general formula (I) as described above and a metal dithiocarbamate of general formula (II-a) as described above, from 0.1 to 5% of a compound D comprising a thiadiazole group, 35117 FR of 0.5 at 3% of another additive, the ratio by weight (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranging from 5: 1 to 1: 10.

The set of characteristics and preferences presented for the base oil, the compound comprising a phosphite group, the compound comprising a thiophosphate group, the compound comprising a dithiocarbamate group, the compound comprising a thiadiazole group and the additional additive applies. also to the lubricant compositions above. In one embodiment of the invention, the lubricating composition is not an emulsion. In another embodiment of the invention, the lubricating composition is an anhydrous composition.

The invention also relates to a process for preparing a lubricating composition as defined above. In one embodiment of the invention, the process comprises at least the following steps: (a) mixing at least one compound comprising a thiadiazole group, at least one base oil and at least one dispersant under stirring and at a temperature of at least 40 ° C for at least 30min, (b) adding at least one compound comprising a phosphite group, at least one compound comprising a dithiophosphate group and at least one compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of general formula (I) as described above and at least one metal dithiocarbamate of general formula (II) as described above with stirring and at a temperature of at least 40 ° C for at least 1h, (c) adding at least one base oil. In one embodiment, the temperature of step (a) ranges from 40 to 70 ° C. In another embodiment, the temperature of step (b) is from 40 to 70 ° C.

In a preferred embodiment of the invention, step (b) further comprises adding at least one additional additive. In another preferred embodiment of the invention, the base oil of step (c) is identical to that of step (a). In another preferred embodiment of the invention, the base oil of step (c) is different from that of step (a).

The set of characteristics and preferences presented for the base oil, the compound comprising a phosphite group, the compound comprising a thiophosphate group, the compound comprising a dithiocarbamate group, the compound comprising a thiadiazole group, the dispersant and the additional additive. also applies to the above process.

The invention also relates to the use of a lubricant composition as defined above for the lubrication of transmissions such as gearboxes, bridges, preferably manual gearboxes of motor vehicles.

In one embodiment, the subject of the invention is the use of a lubricant composition as defined above for the lubrication of a brass mechanical part, preferably present in a transmission member, more preferably in a box. speeds, even more preferably in a manual gearbox. In a preferred embodiment, the subject of the invention is the use of a lubricant composition as defined above for the lubrication of synchronizers present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox. The invention also relates to the use of a lubricant composition as defined above for reducing the fuel consumption of vehicles, particularly motor vehicles. The invention also relates to the use of a lubricant composition as defined above for reducing the wear of gearbox synchronizers, preferably manual gearboxes. The invention also relates to the use of a lubricant composition as defined above for reducing the spalling of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferentially in a manual gearbox. All of the features and preferences presented for the lubricant composition also apply to the above uses. The invention also relates to a method of lubricating transmissions such as gearboxes, bridges, preferably manual gearboxes of motor vehicles, said method comprising at least one step of contacting a lubricant composition as defined above with the transmissions.

In one embodiment, the subject of the invention is a method of lubricating a brass mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox.

In a preferred embodiment, the invention relates to a method of lubricating synchronizers present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox.

The invention also relates to a method for reducing seizure of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox, comprising at least the setting in contact with the mechanical part with a lubricating composition as defined above.

The subject of the invention is also a process for reducing the wear of a gearbox synchronizer, preferably of manual gearboxes, comprising at least putting the synchronizer into contact with a lubricant composition as defined above. . The invention also relates to a method for reducing the peeling of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a manual gearbox, comprising at least bringing the mechanical part into contact with a lubricating composition as defined above. The subject of the invention is also a process for reducing galling, wear and spalling of a mechanical part, preferably present in a transmission member, more preferably in a gearbox, even more preferably in a gearbox. manual gearbox, said method comprising at least one step of contacting the mechanical part with a lubricant composition as defined above. In one embodiment of the method of the invention, the mechanical part is a synchronization device (synchronizer). The set of characteristics and preferences presented for the lubricating composition also applies to the above processes.

The subject of the invention is also the use of at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group and at least one a compound D comprising a thiadiazole group in a base oil for improving the wear, extreme-pressure, friction and anti-seizing properties of a lubricating composition, the compound A comprising a dithiocarbamate group being a mixture of: at least one amine dithiocarbamate of the general formula (I) (compound A-1) in which R 1 and R 2 are independently hydrocarbon-based groups, optionally substituted, comprising from 1 to 30 carbon atoms, - R3, R4 and R5 represent, independently of one another, a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of groups R3, R4 and R5 is not a hydrogen atom, and - at least one metal dithiocarbamate of general formula (II) (compound A-2) wherein R6 and R7 independently represent one of the other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valence of this metal cation. The set of characteristics and preferences presented for the base oil, the compound comprising a phosphite group, the compound comprising a thiophosphate group, the compound comprising a dithiocarbamate group and the compound comprising a thiadiazole group also applies to the use above. The use of these five additives in a lubricant composition simultaneously makes it possible to reduce wear, in particular synchronizers, to improve the extreme-pressure properties, to reduce the coefficient of friction and to improve the anti-seizing properties of the lubricant. lubricating composition. The use of these five additives in a lubricating composition also makes it possible to maintain good anti-peeling properties of the lubricating composition. The invention also relates to a concentrated composition of additives comprising at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group and at least one minus a compound D comprising a thiadiazole group. The set of characteristics and preferences presented for compound A comprising a dithiocarbamate group, for compound B comprising a phosphite group, for compound C comprising a thiophosphate group and compound D comprising a thiadiazole group also applies to the composition of concentrated type of additives above. The various objects of the present invention and their implementations will be better understood on reading the examples which follow. These examples are given for information only, and are not limiting in nature. EXAMPLES Lubricating compositions Nos. 1 to 7 are prepared from the following compounds: - PAO Group IV base oil having a viscosity at 100 ° C. of 6 cSt measured according to ASTDM D445, and viscosity index equal to 125 measured according to ASTM 2270, a dithiocarbamate sold under the name Vanlube EZ by the company Vanderbilt and which is a mixture of: - zinc diamyldithiocarbamate of formula: s 2+ Zn - 2 and diamylamino diamyldithiocarbamate derivative of the formula: ## STR1 ## a phosphite which is the di-n-octyl phosphite sold under the name Irgafos OPH by the company BASF, 35117 FR, of a dithiophosphate, - [(bis-isopropyloxyphosphinothioyl) thio] propionic acid ethyl ester sold under the name Irgalube 63 by BASF, - a dimercaptothiadiazole derivative marketed under RC 8210 by the company Rhein Chemie, - a dispersant, which is a derived from commercial polyisobutylene succinimide sold under the name Doversperse H1015-P by the company DoverChemical, - an antioxidant which is a diphenyl amine sold under the name Irganox L57 by the company BASF, - an anti-corrosion Al which is a benzotriazole marketed under the name RC 5800 by Rhein Chemie, - an anti-corrosion A2 which is a mixture of a C12-C16 alcohol and an alkyl ether of carboxylic acid, the content by weight of alcohol being at most 20% relative to the total weight of the mixture and the content by weight of alkyl ether being at least 70% relative to the total weight of the mixture (Irgacor 843 marketed by BASF). Lubricating compositions Nos. 1 to 7 are described in Table II: the percentages indicated are percentages by weight. Table II Lubricating composition No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 Base oil 96 95.5 95.5 95.5 96.8 96.9 96.9 Dithiocarbamate 1 1 1 1 1 0.7 1 Phosphite 1 1 1 1 0.5 1 0.7 Dithiophosphate 1 1 1 1 0.2 0.4 0.4 Thiadiazole (-) (-) (-) 0.5 0, 7 (-) (-) Anti-corrosion Al (-) 0.5 (-) (-) (-) (-) (-) Anti-corrosion A2 (-) (-) 0.5 (-) (-) ) (-) (-) Dispersant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Lubricating compositions No. 1 to No. 3 and No. 6 to No. 7 are comparative compositions, lubricating compositions No. 4 and No. 5 are according to the invention Test No. 1: evaluation of the properties Lubricating compositions on gearbox synchronizers The objective of this test is to evaluate the anti-wear properties of lubricating compositions against synchronizers. The wear tests of the synchronizers on the lubricant compositions 1 to 5 were carried out on a cone / ring couple under the following conditions (SYNC-13 procedure, SAE 2-A): - Threaded brass ring 54 mm (for example reference 7700 708 152 or 7700 869 430, - JXX gearbox cone, carbonitrided stone ground steel (for example reference 7700 867 612 or 7700 740 880, 35117 FR - Oil: 125 ml of the lubricant composition to be tested, oil level on the lower part of the ring - Machine SAE2 / A adapter SAE / 2 synchro - I = 0,155 m2 / kg - N = 600 rev / min - F = 60 daN - T = 3,5 s (consecutive period between 2 braking consecutive) - n = 20,000 gearshift cycles (20 hours) At the end of these 20,000 cycles, the axial wear of the ring gear of the synchronizer / pinion cone, in mm, was measured. evaluate the anti-wear properties of a lubricant composition in the steel / milk surface contacts one, corresponding to the type of contacts implemented at the level of the synchronizers. The results of the anti-wear properties of the lubricant compositions 1 to 5 on the synchronizers are described in Table III; the lower the value obtained, the better anti-wear properties against synchronizers. Table III Lubricating composition 1 2 3 4 5 Wear synchronizers in mm 0.9 0.9 0.9 0.7 0.3 The results show lubricating composition No. 4 according to the invention can significantly reduce the wear of synchronizers with respect to a lubricating composition comprising a combination of a dithiocarbamate, a dithiophosphate and a phosphite but not including thiadiazole (composition No. 1) or with respect to lubricating compositions comprising a combination of a dithiocarbamate, a dithiophosphate and a phosphite and an anti-corrosion other than a thiadiazole (compositions No. 2 and No. 3). In addition, the results relating to the lubricant composition No. 5 according to the invention show a very clear reduction in the wear of the synchronizers with respect to a lubricating composition comprising a combination of a dithiocarbamate, a dithiophosphate and a dithiocarbamate. phosphite but not comprising thiadiazole (composition No. 1) or with respect to lubricating compositions comprising a combination of a dithiocarbamate, a dithiophosphate and a phosphite, and an anti-corrosion other than a thiadiazole (compositions No. 2 and No. 3), thus demonstrating that a lubricant composition according to the invention has very good anti-wear properties against synchronizers.

Test No. 2: Evaluation of the Anti-Wear Properties of a Composition According to the Invention on Transmission Synchronizers The objective of this test is to confirm the anti-wear properties of a lubricant composition according to the invention with against synchronizers. For this, a synchronizer blocking test with the lubricating composition No. 5 was performed on a ring cone couple under the following conditions (SYNC-40 procedure): - Threaded brass ring 54 mm (for example reference 7700 708 152 or 7700 869 430) - JXX gearbox cone, carbonitrided stone ground steel (for example reference 7700 867 612 or 7700 740 880) - Oil: 250 ml of lubricant composition No. 5, oil level in the middle of the pinion and gear SAE2 machine / SAE adapter / 2 synchro - I = 0.155 m2 / kg - N = 300 rpm - F = 60 daN - T = 6s (consecutive period between 2 consecutive braking) - n = 10 125 cycles of shifting (21 hours) The synchronizer lockout test is considered satisfactory if, during the 10,125 gearshift cycles, the number of cycles in which the disengagement between the cone and the ring requires the application of a against torque greater than 2mN is at most 100 cycles.

The result of the test with the lubricating composition No. 5 is 32, which confirms the very good anti-wear properties of this lubricant composition according to the invention against synchronizers. Test No. 3: Evaluation of the Anti-Wear and Extreme Pressure Properties of the Lubricating Compounds 35117 EN The purpose of this test is to evaluate the anti-wear and extreme pressure properties of lubricating compositions. The anti-wear properties of the lubricating compositions no. 1, No. 5, No. 6 and No. 7 were evaluated by a 4-ball wear test according to D55 1078; this test involving in particular steel balls. A value greater than 0.8mm corresponding to a level of wear that is not acceptable. This test makes it possible more particularly to evaluate the anti-wear properties of a lubricant composition in the steel / steel surface contacts corresponding to the majority of the contacts used in a gearbox.

The extreme pressure properties of lubricant compositions No. 1, No. 5, No. 6 and No. 7 were evaluated by a 4-ball test according to Standard D55 1136; a value less than 90 daN corresponding to extreme pressure properties which are not acceptable. The results of these tests are described in Table V.

Table V Lubricant composition 1 5 6 7 Wear (4-ball test) in mm 0.42 0.72 0.41 0.42 Extreme pressure (test 110 90 70 70 4 beads) in daN The results show that a lubricating composition according to the invention (composition No. 5) has satisfactory anti-wear and extreme pressure properties, even improved over compositions comprising a combination of a dithiocarbamate, a dithiophosphate and a phosphite according to the invention, but not comprising no thiadiazole (compositions No. 1, No. 6 and No. 7). Test No. 4: Evaluation of Anti-Seizing Properties of Lubricating Compositions The objective of this test is to evaluate the anti-seizing properties of lubricating compositions. The anti-seizing properties of lubricant compositions No. 1, No. 5, No. 6 and No. 7 were evaluated by an FZG test according to CEC standard L84 (A / 16, 6R / 120); 35117 EN the higher the value obtained after the test, the better the anti-seizing properties. The results of this test with compositions No. 1, No. 5, No. 6 and No. 7 are described in Table VI.

The results show that a lubricating composition according to the invention (compositions no. 5) has anti-seizing properties which are equivalent to, or even improved over, lubricating compositions comprising: a combination of a dithiocarbamate, a dithiophosphate and a phosphite but not including thiadiazole (compositions No. 1, No. 6 and No. 7). Test No. 5: Evaluation of Anti-Peeling Properties of Lubricating Compositions The objective of this test is to evaluate the anti-peeling properties of lubricating compositions. For this, an FZG C6 test was carried out with the lubricant compositions No. 1, No. 5, No. 6 and No. 7. The purpose of this test is to evaluate the ability of a lubricant composition to protect gear surfaces against pitting damage. PT-C gearing was used and tested on an FZG machine. A constant rotation speed at 1440 rpm has been set, with a constant load also (step 9). The temperature of the lubricating composition to be tested was regulated at 120 ° C.

The test was then run by "run" 8 hours at the beginning, then the appearance of the first scratches on the teeth, the duration of these "run" was decreased. The ultimate goal is to determine the service life of a lubricated lubricated gear by evaluating the flaking surface on each tooth of the gear. The failure criterion is achieved when the surface comprising scales for all teeth is 1 mm 2.

The results are described in Table VII and are expressed in hours; the higher the value obtained, the more important is the time before the appearance of scales on the surface of the pinion and therefore the better anti-flaking properties. The results show that a lubricating composition according to the invention (composition No. 5) exhibits anti-scaling properties which are equivalent to, or even improved over, lubricating compositions comprising a combination. a dithiocarbamate, a dithiophosphate and a phosphite but not including thiadiazole (compositions No. 1, No. 6 and No. 7).

35117 EN

Claims (5)

REVENDICATIONS1. A lubricating composition comprising: - at least one base oil, - at least one compound A comprising a dithiocarbamate group, - at least one compound B comprising a phosphite group, - at least one compound C comprising a dithiophosphate group, and - at least one compound D comprising a thiadiazole group, compound A comprising a dithiocarbamate group being a mixture of: at least one amine dithiocarbamate of general formula (I) (compound A-1) S 1 1 R 3 R 1 N Ce S e HN In which - R 1 and R 2 independently of one another represent optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, - R 3, R 4 and R 5 represent, independently of one another, one of the other a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of the groups R3, R4 and R5 is not a hydrogen atom, and - at least one metal dithiocarbamate of general formula (II) (compound A-2) wherein R 6 and R 7 independently of one another represent optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valence of this metal cation, - the ratio by weight (compound comprising a dithiophosphate group: compound comprising a thiadiazole group) ranging from 5: 1 to 1: 10. 2. The lubricating composition according to claim 1, wherein the compound A comprising a dithiocarbamate group is a mixture of: at least one amine dithiocarbamate of general formula (I) R3 Ri eo HN-R4 Ry R2 (I) in which R 1 and R 2 represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms; R 3, R 4 and R 5 represent, independently of one another, a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, it being understood that at least one of R3, R4 and R5 is not a hydrogen atom, and - at least one metal dithiocarbamate of general formula (II- a), wherein R6 and R7 independently of one another are linear alkyl hydrocarbon groups. 3. Composition according to claim 2 wherein R6 and R7 represent independently of each other linear alkyl groups comprising from 4 to 12 carbon atoms. 35117 EN 4. Lubricating composition according to any one of the preceding claims comprising from 0.1 to 5% by weight of compounds A comprising a dithiocarbamate group, relative to the total weight of the lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, advantageously from 0.5 to 1%. 5. Composition according to any one of the preceding claims comprising from 0.1 to 3% by weight of the mixture of amine dithiocarbamate corresponding to formula (I) (compound A-1) and of metal dithiocarbamate corresponding to the formula ( II) (compound A-2), preferably from 0.1 to 2% by weight, advantageously from 0.5 to 2% by weight, relative to the total weight of the composition. A lubricating composition according to any one of the preceding claims wherein compound B comprising a phosphite group is selected from phosphite monoesters, phosphite diesters or phosphite triesters, alone or in admixture. Lubricating composition according to any one of the preceding claims comprising from 0.1 to 5% by weight of compound B comprising a phosphite group, relative to the total mass of lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, even more preferably from 0.5 to 1%. A lubricating composition according to any one of the preceding claims wherein compound C comprising a dithiophosphate group is selected from the group consisting of ammonium dithiophosphates, amine dithiophosphates, ester dithiophosphates and metal dithiophosphates, taken alone. or in mixture. Lubricating composition according to any one of the preceding claims comprising from 0.1 to 5% by weight of compound C comprising a dithiophosphate group, relative to the total weight of lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, even more preferably from 0.5 to 1%. A lubricating composition according to any one of the preceding claims wherein compound D comprising a thiadiazole group is selected from the group consisting of: - a compound of formula (V-a) 35117 FR6. Wherein R27 and R28, which may be identical or different, independently represent a hydrogen atom or a linear or branched, saturated or unsaturated alkyl group comprising from 1 to 30 carbon atoms, - a represents an integer ranging from 1 to 3, - b represents an integer ranging from 1 to 3, - a compound of formula (Vb) - R 28 HN-N (Vb) in which - R 28 represents a hydrogen atom or a linear or branched, saturated or unsaturated alkyl group comprising from 1 to 30 carbon atoms; b represents an integer ranging from 1 to 3; a mixture of at least one compound of formula (Va) and at least one compound of formula (Vb). A lubricating composition according to any one of the preceding claims comprising from 0.1 to 5% by weight of compound D comprising a thiadiazole group, based on the total weight of the lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%, even more preferably from 0.5 to 1%. Lubricating composition according to any one of the preceding claims, in which the ratio by weight (compound C comprising a dithiophosphate group: compound D comprising a thiadiazole group) ranges from 3: 1 to 1: 8, preferably from 2: 1 to 1: 5, advantageously from 1: 1 to 1: 5. A lubricating composition according to any one of the preceding claims further comprising an antioxidant selected from the group consisting of aromatic amines or phenol derivatives. A lubricant composition according to any one of the preceding claims further comprising a dispersant derived from polyisobutene. A lubricating composition according to any one of the preceding claims having a kinematic viscosity at 100 ° C according to ASTM D445 of between 4 and 41 cSt, preferably between 4.1 and 32.5. cSt, preferably between 6 and 18.5 cSt. Use of a lubricant composition according to any one of claims 1 to 15 for lubricating transmissions such as gearboxes, axles, preferably manual transmissions of motor vehicles. Use of a lubricant composition according to any one of claims 1 to 15 for reducing the fuel consumption of vehicles, particularly motor vehicles. Use of a lubricant composition according to any one of claims 1 to 15 for reducing the wear of gearbox synchronizers, preferably of manual gearboxes. Use of at least one compound A comprising a dithiocarbamate group, at least one compound B comprising a phosphite group, at least one compound C comprising a dithiophosphate group and at least one compound D comprising a thiadiazole group in a group base oil for improving the anti-wear, extreme-pressure, friction and anti-seizing properties of a lubricating composition, compound A comprising a dithiocarbamate group being a mixture of: at least one amine dithiocarbamate of the formula (I) (compound A-1) wherein R 1 and R 2 independently of one another represent hydrocarbon groups, optionally substituted, comprising 1 to 30 carbon atoms, R3, R4 and R5 independently of one another represent a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms, being 35117 FR 15. 16. 17. 18 19. 25 R2 understood that at least one of the groups R3, R4 and R5 is not a hydrogen atom, and - at least one metal dithiocarbamate of general formula (II) (compound A-2), 7 S 1 1 R6 Ce N R7 n (II) wherein R6 and R7 independently of one another are optionally substituted hydrocarbon groups having 1 to 30 carbon atoms, M is a metal cation and n is the valency of said metal cation. 35117 FR mn +