WO2013120965A1 - Lubricating compositions for transmissions - Google Patents

Description

 LUBRICATING COMPOSITIONS FOR TRANSMISSIONS

Technical area

 The present invention relates to lubricating compositions for transmissions, in particular for manual gearboxes, bridges or double clutches. The lubricant compositions according to the invention simultaneously have in particular good properties of extreme pressure, anti-wear and a low coefficient of friction.

Technological background

It is very difficult to formulate lubricating compositions having simultaneously good extreme pressure properties, good antiwear properties and good friction properties, as well as good anti-seizing 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 seizure 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 used as the extreme pressure agent to form thiophosphonic derivatives for example, whose properties are notably 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 controlled 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. US2009 / 011964, US 5674820 and US 5872085 disclose a lubricating composition comprising a compound comprising a dithiocarbamate moiety, a compound comprising a phosphite moiety and a compound comprising a dithiophosphate moiety. However, none of these documents concretely demonstrates that such a combination makes it possible simultaneously to obtain good extreme-pressure, anti-wear and friction properties. In addition, no indication is given in these documents as to the improvement of the anti-seizing properties of these lubricating compositions.

Brief description of the invention

 The applicant company has developed a new lubricant composition comprising at least four essential additives to simultaneously obtain good extreme-pressure, anti-wear, friction and anti-seizing properties.

 This specific combination of additives is based on the presence of at least one compound comprising a metal dithiocarbamate group, at least one compound comprising an amine dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group.

 The lubricating composition according to the invention, comprising at least one compound comprising a metal dithiocarbamate group, at least one compound comprising an amine dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group, present simultaneously good properties in wear, extreme pressure, friction and anti-seizing.

 Moreover, this lubricant composition also has good properties in terms of oxidation and corrosion.

The 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 and at least one compound comprising a dithiophosphate group, the compound comprising a dithiocarbamate group being a mixed: at least one amine dithiocarbamate of general formula (Ic)

dans laquelle

in which

R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms,

 • Rio, Ru and R12 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 Rio, Ru and R12 is not a hydrogen atom, and

at least one metal dithiocarbamate of general formula (1-e),

dans laquelle R₁₇ et Ri₈ représentent indépendamment l'un de l'autre des groupes hydrocarbonés, éventuellement substitués, comprenant de 1 à 30 atomes de carbone, M représente un cation métallique et n est la valence de ce cation métallique.

wherein R ₁₇ and R ₈ independently of one another hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, M represents a metal cation and n is the valence of the metal cation.

In one embodiment, the composition according to the invention may further comprise another compound comprising at least one dithiocarbamate group. Preferably, 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.

Preferably, the bisdithiocarbamate has the formula (la), in which R 1, R ₂ , R 3 and R ₄ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R ₅ represents a hydrocarbon group of 1 to 8 carbon atoms:

Preferably, the ammonium dithiocarbamate has the formula (Ib), in which R ₆ and R ₇ represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms:

Preferably, the dithiocarbamate ester has the formula (ld) wherein R 13 and R _i4 represent independently of the other hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, R _i5 and Ri ₆ represent, independently of one another, a hydrocarbon group of 1 to 18 carbon atoms:

De préférence, la composition lubrifiante comprend de 0,1 à 5% en masse de composés comprenant un groupement dithiocarbamate, par rapport à la masse totale de composition lubrifiante, de préférence de 0,2 à 4%, plus préférentiellement de 0,3 à 2%, encore plus préférentiellement de 0,5 à 1%.

Preferably, the lubricating composition comprises from 0.1 to 5% by weight of compounds comprising a dithiocarbamate group, with respect 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%.

 Preferably, the lubricating composition comprises from 0.1 to 3% by weight of the mixture of compounds corresponding to formula (Ic) and (1-e), preferably from 0.1 to 2% by weight, advantageously from 0, 5 to 2% by weight.

 Preferably, the compound comprising a phosphite group is chosen from phosphite monoesters, phosphite diesters or phosphite triesters, taken alone or as a mixture.

Preferably, the phosphite monoester has the general formula (II-a) in its alcohol and / or ketone form, in which R ₁₉ represents an optionally substituted hydrocarbon group of 1 to 30 carbon atoms:

 form alcohol form ketone

Preferably, the phosphite diester has the general formula (II-b) in its alcohol and / or ketone form, in which R ₂₀ and R ₂ i represent, independently of each other, optionally substituted hydrocarbon groups of 1 to 30 carbon atoms:

form alcohol form ketone Preferably, the phosphite triester has the general formula (II-c) wherein R _{22, 2} 3 and R ₂₄ each independently of the other hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms :

 Preferably, the lubricating composition comprises from 0.1 to 5% by weight of compound comprising a phosphite 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%.

 Preferably, the compound comprising a dithiophosphate group is selected from the group consisting of ammonium dithiophosphates, amine dithiophosphates, ester dithiophosphates and metal dithiophosphates, alone or in admixture.

Preferably, the ammonium dithiophosphate has the general formula (III-a), in which R ₂₅ and R ₂₆ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms:

Preferably, the amine dithiophosphate has the general formula (III-b), in which R ₂₇ and R ₂₈ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R ₂₉ , R ₃₀ and R _3i 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 R ₂₉ , R ₃₀ and R _3i is not a hydrogen atom:

Preferably, the ester dithiophosphate has the general formula (III-c), in which R ₃₃ and R ₃₄ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, R ₃₅ and R ₃₆ represent, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms:

Preferably, the metal dithiophosphate has the general formula (III-d), in which R ₃₇ and R ₃₈ represent, independently of each 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:

Preferably, the lubricating composition comprises from 0.1 to 5% by weight of compound 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%. Preferably, the lubricating composition further comprises an antioxidant selected from the group consisting of aromatic amines or phenol derivatives. By phenol derivatives within the meaning of the present invention is meant any compound comprising at least one phenol or phenoxy group.

 Preferably, the lubricating composition further comprising a dispersant derived from polyisobutene.

 Preferably, the lubricating composition further comprises a polymer of polymethacrylate type.

 Preferably, the lubricating composition has a kinematic viscosity at 100 ° C according to ASTM D445 of between 4 and 40 cSt, preferably between 4.1 and 32.5 cSt, preferably between 6 and 18.5 cSt.

 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.

 Preferably, the lubricant composition is used to reduce the fuel consumption of vehicles, particularly motor vehicles.

 The invention also relates to the use of at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group in a base oil to improve the properties of wear, extreme pressure, friction and anti-seizing of a lubricating composition, the compound comprising a dithiocarbamate group being a mixture:

 at least one amine dithiocarbamate of general formula (I-c):

dans laquelle: R (Ic)

in which:

R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms,

 • Rio, Ru and R12 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 Rio, Ru and R12 is not a hydrogen atom, and

at least one metal dithiocarbamate of general formula (1-e):

dans laquelle R₁₇ et Ri₈ représentent indépendamment l'un de l'autre des groupes hydrocarbonés, éventuellement substitués, comprenant de 1 à 30 atomes de carbone, M représente un cation métallique et n est la valence de ce cation métallique.

wherein R ₁₇ and R ₈ independently of one another hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, M represents a metal cation and n is the valence of the metal cation.

 In one embodiment of the invention, the lubricating composition consists essentially of at least one base oil, at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group, the compound comprising a dithiocarbamate group being a mixture:

 at least one amine dithiocarbamate of general formula (I-c):

R 10

 R ". <±>

 N HN Ru (I-c)

Rc R ₂ in which:

R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms,

 • Rio, Ru and R12 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 Rio, Ru and R12 is not a hydrogen atom, and

at least one metal dithiocarbamate of general formula (1-e):

dans laquelle R₁₇ et Ri₈ représentent indépendamment l'un de l'autre des groupes hydrocarbonés, éventuellement substitués, comprenant de 1 à 30 atomes de carbone, M représente un cation métallique et n est la valence de ce cation métallique.

wherein R ₁₇ and R ₈ independently of one another hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, M represents a metal cation and n is the valence of the metallic cation.

Detailed description of the invention

 dithiocarbamate

The lubricating composition according to the invention comprises at least one compound 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 the general formula (1-e) wherein R ₁₇ and R ₈ independently of u n of the other hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, M represents a metal cation and n is the valence of this metal cation:

Preferably, the metal is selected from the group 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. The preferred metals are zinc, molybdenum and antimony, preferably zinc and molybdenum, preferably zinc. Mixtures of metals can be used. Metallic dithiocarbamates are neutral as represented in the formula (1-e) or basic when a stoichiometric excess of metal is present.

Preferably, R ₁₇ and R ₈ represent independently of the other hydrocarbon groups, optionally substituted, comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, more preferably from 5 to 12 carbon atoms.

Preferably, R ₁₇ and R ₈ represent independently of the other hydrocarbon groups, unsubstituted, said hydrocarbon groups may be alkyl, alkenyl, alkynyl comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, more preferably 5 to 12 carbon atoms, phenyl or benzyl.

Preferably, R ₁₇ and R ₈ independently of one another linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups comprising 2 to 24 carbon ca rbone, more preferably from 3 to 18 carbon atoms, more preferably from 5 to 12 carbon atoms.

Preferably, R ₁₇ and R ₈ independently of one another hydrocarbon groups optionally substituted by one or more heteroatoms such as oxygen atom, nitrogen atom, 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 preparing these compounds is described in US Patent 2492314. Suppliers of such additives are, for example, Vanderbilt, Rhein Chemie, Adeka, 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.

Preferably, the metal dithiocarbamate is a molybdenum dithiocarbamate of formula (Ic-1), in which R ₁₇ and R ₈ have the same meaning as in formula (1-e):

Preferably, the metal dithiocarbamate is a zinc dithiocarbamate of formula (le-2), in which R ₁₇ and R ₈ have the same meaning as in formula (1-e):

Particularly preferred compounds of formula (Ic-2) are such that R ₁₇ and R ₈ independently of one another the groups linear alkyl hydrocarbon compounds comprising from 5 to 12 carbon atoms and are, for example, zinc diamyldithiocarbamate and zinc dibutyldithiocarbamate.

The amine dithiocarbamate is an amine dithiocarbamate of the general formula (Ic), in which R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, Rio, Ru and R ₁₂ 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 Rio, Ru and R ₁₂ is not a hydrogen atom:

S

 Rio

^R 8 \ Q <±> I

 HN R (I-c)

R ₉ ^R 12 Preferably, R ₈ and R ₉ 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.

Preferably, R ₈ and R ₉ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl or alkynyl groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 24 carbon atoms. 18 carbon atoms, even more preferably 5 to 12 carbon atoms, phenyls or benzyls.

Preferably, R ₈ and R ₉ 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 5 to 12 carbon atoms.

Preferably, R ₈ and R ₉ represent, independently of one another, hydrocarbon groups optionally substituted with one or more heteroatoms such as the oxygen atom, the nitrogen atom, the sulfur atom, the phosphorus atom, preferably by one or more oxygen atoms.

Preferably, R _10, R ₁₁ and R ₁₂ independently of one another represent a hydrocarbon group 2 to 24 carbon atoms, more preferably 3 to 18 carbon atoms, even more preferably 5 to 12 carbon atoms.

 Particularly preferred compounds are diamyl amine diamyldithiocarbamate and diamyl amine dibutyldithiocarbamate.

Commercial compounds are for example Vanlube ^® EZ.

 Preferably, the dithiocarbamate is a mixture of the dithiocarbamates of formula (I-c) and (I-e-2) described 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.

In a first embodiment, this other dithiocarbamate compound is a bisdithiocarbamate of general formula (Ia), in which R 1, R ₂ , R 3 and R ₄ represent, independently of each other, optionally substituted hydrocarbon groups comprising 1 to 30 carbon atoms, R ₅ represents a hydrocarbon group of 1 to 8 carbon atoms:

Preferably, R 1, R ₂ , R 3 and R ₄ 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 preferentially from 5 to 12 carbon atoms. Preferably, R 1, R ₂ , R 3 and R ₄ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R 1, R ₂ , R 3 and R ₄ represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R 1, R ₂ , R ₃ and R ₄ independently of one another represent hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably atoms. oxygen.

Preferably, R ₅ represents a hydrocarbon group of 2 to 6 carbon atoms.

 Commercial compounds are for example Vanlube® 7723 or Additin® RC 6340.

In a second embodiment, this other dithiocarbamate compound is an ammonium dithiocarbamate of general formula (Ib), in which R ₆ and R ₇ represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to at 30 carbon atoms:

Preferably, R ₆ and R ₇ 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. carbon atoms.

Preferably, R ₆ and R ₇ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups. Preferably, R ₆ and R ₇ represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₆ and R ₇ represent, independently of each other, hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably with oxygen atoms.

In a third embodiment, another dithiocarbamate compound is a dithiocarbamate ester of general formula (ld) wherein R da ns _{i3 i4} and R independently of one another hydrocarbon groups, optionally substituted, comprising 1 to 30 carbon atoms, R ₁₅ and R ₁₆ represent, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms:

Preferably, R and R _{i3 i4} represent independently of the other hydrocarbon groups, optionally substituted, comprising from 2 to 24 carbon atoms, more preferably from 3 to 18 carbon atoms, more preferably from 5 to 12 carbon atoms.

Preferably, R and R _{i3 i4} represent independently of the other hydrocarbon groups, unsubstituted, said hydrocarbon groups may be alkyl, alkenyl, alkynyl, phenyl or benzyl.

Preferably, R and R _{i3 i4} represent independently of the other hydrocarbon groups linear or branched alkyls, more preferably hydrocarbon groups linear alkyls.

Preferably, R and R _{i3 i4} represent independently of the other hydrocarbon groups optionally substituted by oxygen, nitrogen, sulfur and / or phosphorus, preferably oxygen atoms. Preferably, R ₁₅ and R ₁₆ represent, independently of one another, hydrocarbon groups of 2 to 6 carbon atoms.

Phosphite

 The lubricant composition according to the invention comprises at least one compound comprising a phosphite group. For the sake of simplification of the description, the compound comprising a phosphite group is called "phosphite" in the following description.

 By phosphite is meant a phosphite ester, whether it is a phosphite monoester, a phosphite diester or a phosphite triester, taken alone or in mixture.

 Phosphite monoesters are found in two equilibrium forms, a "ketone" form and an "alcohol" form. It is the same for the phosphite diesters.

A phosphite which may be used may be a phosphite monoester of general formula (IIa) in its alcohol and / or ketone form, in which R ₁₉ represents an optionally substituted hydrocarbon group of 1 to 30 carbon atoms:

 form alcohol form ketone

Preferably, R _i9 represents an optionally substituted hydrocarbon-based group comprising from 2 to 24 carbon atoms, more preferably from 3 to 20 carbon atoms, even more preferentially from 4 to 18 carbon atoms, even more preferably from 6 to 16 carbon atoms. carbon atoms, more preferably 8 to 12 carbon atoms.

Preferably, R ₁₉ represents an unsubstituted hydrocarbon group, said hydrocarbon group possibly being an alkyl, alkenyl, alkynyl, phenyl or benzyl group. Preferably, R _i9 represents a linear or branched alkyl hydrocarbon group, more preferably a linear alkyl hydrocarbon group.

Preferably, R ₁₉ represents a hydrocarbon group substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably oxygen atoms.

Examples of phosphite monoesters, there may be mentioned a I ky I (Ci ₀₎ bisphenol A phosphite, have ky I (C ₂ -C ₅₎ bisphenol A phosphite.

A phosphite which may be used may also be a phosphite diester of general formula (II-b) in its alcohol and / or ketone form, in which R ₂ o and R _2i represent, independently of each other, optionally substituted hydrocarbon groups , from 1 to 30 carbon atoms:

 form alcohol form ketone

Preferably R ₂₀ and R _2i 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.

Preferably, R ₂₀ and R _2i represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₂₀ and R _2i are independently from each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₂₀ and R _2i represent hydrocarbon groups substituted with oxygen, nitrogen, sulfur and / or phosphorus, preferably oxygen atoms. Examples of phosphite diesters that may be mentioned include dimethyl phosphite, diethyl phosphite, diisopropyl phosphite, dibutyl phosphite, dihexyl phosphite, dicylohexyl phosphite, diisodecyl phosphite, di-n-octyl phosphite, dibenzyl phosphite, diphenyl phosphite, dioleyl phosphite.

A usable phosphite triester may also be a phosphite of general formula (II-c) wherein R _{22, 2} 3 and R ₂₄ each independently of the other hydrocarbon groups, optionally substituted, containing 1 to 30 carbon of carbon:

R ₂₂ , R ₂₃ and R ₂₄ preferably represent optionally substituted hydrocarbon groups comprising from 2 to 24 carbon atoms, more preferably from 3 to 20 carbon atoms, more preferably from 4 to 18 carbon atoms, and even more preferably preferably from 6 to 16 carbon atoms, more preferably from 8 to 12 carbon atoms.

Preferably, R ₂₂ , R ₂₃ and R ₂₄ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₂₂ , R ₂₃ and R ₂₄ represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₂₂ , R ₂₃ and R ₂₄ represent hydrocarbon groups substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably oxygen atoms.

As examples of phosphite triesters, mention may be made of 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, 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 ^{® products} marketed by Rhodia.

 The lubricant composition according to the invention 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%. more preferably from 0.5 to 1%.

dithiophosphate

 The lubricating composition according to the invention comprises at least one compound comprising a dithiophosphate group. For the sake of simplification of the description, the compound comprising a dithiophosphate group is called "dithiophosphate" in the following description.

 A suitable dithiophosphate is a dithiophosphate 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.

représentent indépendamment l'un de l'autre des groupes hydrocarbonés, éventuellement substitués, comprenant de 1 à 30 atomes de carbone : In a first embodiment, the dithiophosphate is an ammonium dithiophosphate of general formula (III-a), wherein R ₂₅ and R ₂ 6

represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms:

Preferably, R ₂₅ and R ₂ 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 18 carbon atoms. 12 carbon atoms.

Preferably, R ₂₅ and R ₂₆ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₂₅ and R ₂₆ represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₂₅ and R ₂₆ represent, independently of one another, hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably oxygen atoms.

 Examples of commercial products are ammonium dimethyl dithiophosphates, ammonium diethyl dithiophosphates, ammonium dibutyl dithiophosphates.

In a second embodiment, the dithiophosphate is an amine dithiophosphate of the general formula (III-b), in which R ₂₇ and R ₂₈ represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to at 30 carbon atoms, R ₂₉ , R ₃₀ and R _3i 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 R groups ₂₉ , R ₃₀ and R _3i is not a hydrogen atom:

Preferably, R ₂₇ and R ₂₈ 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. carbon atoms.

Preferably, R ₂₇ and R ₂₈ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₂₇ and R ₂₈ represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₂₇ and R ₂₈ represent, independently of one another, hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably with oxygen atoms.

Preferably, R ₂₉ , R ₃₀ and R _3i independently of one another represent a hydrocarbon group 2 to 24 carbon atoms, more preferably 3 to 18 carbon atoms, even more preferably 5 to 12 carbon atoms. .

Commercial compounds are, for example Additin ^® RC 3880.

In a third embodiment, the dithiophosphate is an ester dithiophosphate of the general formula (III-c), in which R ₃₃ and R ₃₄ represent, independently of each other, optionally substituted hydrocarbon groups comprising from 1 to at 30 carbon atoms, R ₃₅ and R ₃₆ represent, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms:

Preferably, R ₃₃ and R ₃₄ 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. carbon atoms.

Preferably, R ₃₃ and R ₃₄ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₃₃ and R ₃₄ represent independently of each other linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₃₃ and R ₃₄ represent, independently of one another, hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably oxygen atoms.

Preferably, R ₃₃ and R ₃₄ represent, independently of one another, a hydrocarbon group of 2 to 6 carbon atoms.

Preferably, R ₃₅ and R ₃₆ represent independently of each other hydrocarbon groups of 2 to 6 carbon atoms.

Commercial compounds are for example Irgalube ^® 63.

In a fourth embodiment, the dithiophosphate is a metal dithiophosphate of general formula (III-d), in which R ₃₇ and R ₃₈ represent, independently of each 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:

Preferably, the metal is selected from the group 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. The preferred metals are zinc, molybdenum, antimony, preferably zinc and molybdenum, preferably zinc. Mixtures of metals can be used. Metal dithiophosphates are neutral as exemplified in formula (III-d) or basic when a stoichiometric excess of metal is present.

Preferably, R ₃₇ and R ₃₈ 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. carbon atoms.

Preferably, R ₃₇ and R ₃₈ represent, independently of each other, unsubstituted hydrocarbon groups, said hydrocarbon groups possibly being alkyl, alkenyl, alkynyl, phenyl or benzyl groups.

Preferably, R ₃₇ and R ₃₈ represent, independently of one another, linear or branched alkyl hydrocarbon groups, more preferably linear alkyl hydrocarbon groups.

Preferably, R ₃₇ and R ₃₈ represent, independently of one another, hydrocarbon groups optionally substituted with oxygen, nitrogen, sulfur and / or phosphorus atoms, preferably with oxygen atoms.

 Useful metal dithiophosphates are compounds well known to those skilled in the art.

Commercial compounds are, for example Additin 3038 RC, the RC Additin 3045, the Additin ^® RC 3048, the Additin ^® RC 3058, the Additin ^® RC 3080, the Additin ^® RC 3180, Additin ^® RC 3212, Additin ^® RC 3580, Kikulube ^® Z112, Lubrizol ^® 1371, Lub zol ^® 1375, Lub zol ^® 1395, Lub zol ^® 5179, Oloa ^® 260, Oloa ^® 267.

Preferably, the metal dithiophosphate is a molybdenum dithiophosphate of formula (III-d-1), in which R ₃₇ and R ₃₈ have the same meaning as in formula (III-d):

Preferably, the metal dithiophosphate is a zinc dithiophosphate of formula (III-d-2), wherein R ₃₇ and R ₃₈ have the same meaning as in formula (III-d):

The lubricating composition according to the invention comprises from 0.1 to 5% by weight of dithiophosphate, relative to the total weight of the lubricating composition, preferably from 0.2 to 4%, more preferably from 0.3 to 2%. more preferably from 0.5 to 1%.

Base oil

 The lubricant compositions according to the invention may contain any type of mineral lubricating base, synthetic or natural, animal or vegetable adapted (s) to 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. Saturated Content Content in Viscosity Index Sulfur (VI)

 Group 1 Mineral oils <90%> 0.03% 80≤ Vl <120

Group II Oils ≥ 90% ≤ 0.03% 80≤ Vl <120 hydrocracked

 Group III ≥ 90% ≤ 0.03%> 120

 Hydrocracked oils or

hydro-isomerized

 Group IV Polyalphaolefines (PAO)

 Group V Esters and other bases not included in groups 1 to

 IV

 The mineral base oils according to the invention include all types of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, desalphating, solvent dewaxing, hydrotreatment, hydrocracking and hydroisomerization, hydrofinishing.

 The base oils of the compositions according to the present invention may also be synthetic oils, such as certain esters of carboxylic acids and alcohols, or polyalphaolefins. The polyalphaolefins used as base oils are, for example, obtained from monomers containing from 4 to 32 carbon atoms (for example octene, decene) and a viscosity at 100 ° C. of between 1.5 and 15 cSt according to the standard. ASTM D445. Their weight average molecular weight is typically between 250 and 3000 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, adapted for use in a gearbox, in particular in a gearbox of motor vehicles, particularly in a manual gearbox.

Preferably, 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 90% by weight, relative to the total mass of the lubricating compositions according to the invention.

 Preferably, the lubricant compositions according to the invention comprise Group I and / or III mineral bases, or Group IV synthetic bases according to the API classification.

 Preferably, the lubricant compositions according to the invention have a kinematic viscosity at 100 ° C., measured according to the ASTM D445 standard of between 4 and 41 cSt, according to classification SAE J 306, preferably between 4.1 and 32.5 cSt.

 Preferred grades are all grades from 75W to

140, including grades 75W, 75W80 and 75W90.

 Preferably, the lubricant compositions according to the invention have a viscosity index (VI) greater than 120 (ASTM 2270 standard).

Other additives

 The lubricating 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, corrosion inhibitors, 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, copolymers of styrene and acrylate. The preferred polymers are polymethacrylates (PMA).

 The preferred dispersants are polyisobutylenes (PIB), polyisobutylene succinic anhydride, amino derivatives of polyisobutylene succinic anhydride (PIB succinimides).

Preferred antioxidants are, for example, amino antioxidants, preferably diphenylamines, in particular dialkylphenylamines, such as octadiphenylamines, phenyl-alpha-naphthyl amines, or phenolic antioxidants (dibutylhydroxytoluene BHT and derivatives) or sulfur-containing antioxidants

(sulfurized phenates).

 The preferred anti-corrosion additives are phenolic derivatives, in particular ethoxylated phenol derivatives substituted with ortho-position alkyl groups. The corrosion inhibitors may be derivatives of dimercaptothiadiazole.

 In one embodiment of the invention, the lubricant composition comprises:

 - 80-98.5% of a base oil,

 from 0.5 to 3% of a compound comprising a phosphite group, from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of general formula (Ic) as described above and a metal dithiocarbamate of general formula (1-e) as described above.

In one embodiment of the invention, the lubricant composition comprises:

 - 80-98.5% of a base oil,

 from 0.5 to 3% of a compound comprising a phosphite group, from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of the general formula (Ic) as described above and a metal dithiocarbamate of the general formula (Ic-2) as described above.

 In one embodiment of the invention, the lubricant composition comprises:

 - 80-98% of a base oil,

 from 0.5 to 3% of a compound comprising a phosphite group,

from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of general formula (Ic) as described above and a metal dithiocarbamate of formula general (1-e) as described above,

 from 0.5 to 3% of at least one other additive.

 The additional additive may be selected from the other additives described above.

 Preferably, the other additive may be selected from the group consisting of polymers, antioxidants, corrosion inhibitors, dispersants and mixtures thereof.

 Preferably, the other additive is a mixture of at least one antioxidant and at least one dispersant.

 Preferably, the other additive is a mixture of at least one polysiobutylene succinimide and at least one dialkylphenylamine.

In one embodiment of the invention, the lubricant composition essentially consists of:

 - 80-98.5% of a base oil,

 from 0.5 to 3% of a compound comprising a phosphite group, from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, compound being a mixture of at least one amine dithiocarbamate of general formula (Ic) as described above and a metal dithiocarbamate of general formula (1-e) as described above.

In one embodiment of the invention, the lubricant composition essentially consists of:

 - 80-98.5% of a base oil,

from 0.5 to 3% of a compound comprising a phosphite group, from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of general formula (Ic) as described above and a metal dithiocarbamate of formula general (le-2) as described above.

In one embodiment of the invention, the lubricant composition consists essentially of:

 - 80-98% of a base oil,

 from 0.5 to 3% of a compound comprising a phosphite group, from 0.5 to 3% of a compound comprising a dithiophosphate group, from 0.5 to 3% of a compound comprising a dithiocarbamate group, this compound being a mixture of at least one amine dithiocarbamate of the general formula (Ic) as described above and a metal dithiocarbamate of the general formula (1-e) as described above, from 0.5 to 3% of at least one other additive.

 The additional additive may be selected from the other additives described above.

 Preferably, the other additive may be selected from the group consisting of polymers, antioxidants, corrosion inhibitors, dispersants and mixtures thereof.

 Preferably, the other additive is a mixture of at least one antioxidant and at least one dispersant.

 Preferably, the other additive is a mixture of at least one polysiobutylene succinimide and at least one dialkylphenylamine.

The invention also relates to a method of lubricating transmissions such as gearboxes, bridges, preferably manual gearboxes of motor vehicles, said method comprising a step of contacting the lubricating composition as defined above with transmissions such as gearboxes. Preferably, this method simultaneously makes it possible to reduce the wear, to improve the extreme-pressure properties, to reduce the friction and to improve the anti-seizing properties of the lubricant composition. Advantageously, this method makes it possible to reduce the fuel consumption of vehicles, in particular of motor vehicles.

 The use of these four additives in a lubricating composition simultaneously makes it possible to reduce wear, improve the extreme-pressure properties, reduce the coefficient of friction and improve the anti-seizing properties of the lubricant composition.

 In a preferred embodiment, the lubricating composition comprises at least one base oil, at least one compound comprising a metal dithiocarbamate group of formula (1-e), at least one compound comprising an amine dithiocarbamate group of formula (lc ), at least one compound comprising a phosphite group, at least one compound comprising a dithiophosphate group, at least one antioxidant and at least one dispersant. The presence of an antioxidant and a dispersant, and in particular the presence of the dispersant, does not impair the extreme-pressure, wear, friction and anti-seize properties, which are always very good and at the same time ensures excellent resistance to oxidation. It is surprising to note that the use of the dispersant makes it possible to significantly improve the resistance to oxidation.

EXAMPLES

 Example 1

 Lubricating compositions 1 to 7 are prepared from:

 A PAO group IV base oil having a viscosity at 100 ° C. of 6 cSt according to the ASTDM D445 standard and a viscosity index equal to 125 according to the ASTM 2270 standard,

 • a dithiocarbamate (Vanlube EZ) which is a mixture:

- Zinc diamyldithiocarbamate of formula

 and diamyl amine diamyldithiocarbamate of formula,

 A phosphite Pi which is di-n-octyl phosphite,

 • a dithiophosphate, 3 - [(bis-isopropyloxyphosphinothioyl) thio] propionic acid ethyl ester.

 Table I - Mass Composition (%) of Lubricating Compositions 1 to 7

The properties of wear, extreme pressure and friction of these lubricant compositions 1 to 7 are then measured. TABLE II Properties of Lubricating Compositions 1 to 7

¹ Test 4B (4 balls) wear D55 1078

² Test 4B (4 balls) EP (Extreme Pressure) D55 1136

³ The frictional properties of the formulas were evaluated using a reciprocating type tribometer Cameron-Plint TE-77. The operating principle is for example described in the publication "Friction Force Measurement in Reciprocating Tribometers" AG Plint, published by STLE (Society of Tribologists and Lubrication Engineers) in 2011. The procedure used measures the coefficient of friction of a roller on a plane, all immersed in the test lubricant, under conditions of temperature (60 ° C, 100 ° C and 140 ° C), load (50, 100, 150 and 200N) and frequency (5, 10 , 20 and 40 Hz) variables in order to reproduce the friction conditions encountered in the control mechanisms of the gearboxes in use. The roller stroke on the plane, that is to say the reciprocating back and forth movement, is set at 7 mm. The duration of the test is 10 min. The reduction of the friction under these test conditions makes it possible to indicate a reduction in shifting forces and friction losses in the gears of the gearbox operating with the type of lubricant studied. The value of the measured coefficient of friction μιηίη, taken at different temperatures, corresponds to the minimum value of the coefficient of friction taken on the average of the 4 charges for the last minute of test.

Lubricating compositions 1 to 6 are control lubricating compositions comprising only one or two of the three essential additives to the invention. Lubricating compositions 1 to 6 do not simultaneously have good properties in anti-wear, extreme pressure and friction. Only the composition lubricant 7, which is a lubricant composition according to the invention, has simultaneously good properties in anti-wear, extreme pressure and friction. Example 2

 Lubricating compositions 8 to 9 according to the invention are then prepared from:

 A PAO group IV base oil having a viscosity at 100 ° C. of 6 cSt according to the ASTDM D445 standard and a viscosity index equal to 125 according to the ASTM 2270 standard,

 ®

 A dithiocarbamate (Vanlube EZ) which is a mixture of zinc diamyldithiocarbamate and diamylamino dithiocarbamate,

 A phosphite Pi which is di-n-octyl phosphite,

 A dithiophosphate, 3 - [(bis-isopropyloxyphosphinothioyl) thio] propionic acid ethyl ester.

An aminated antioxidant, a dialkylated diphenylamine with C ₄ and C _{8 groups} ,

A dispersant derived from polyisobutylene, in particular derived from polyisobutylene succinimide.

Table III - Mass Composition (%) of Lubricating Compositions 7 to 9

 The extreme pressure properties (via the FZG test), oxidation and corrosion of these lubricant compositions 7 to 9 are then measured.

Table IV - Properties of Lubricating Compositions 7 to 9

⁴ CEC L84 (A / 16,6R / 120)

5 GFC T-021-A-90 ⁶ GFC T-022-A-90

⁷ ASTM D665

⁸ ASTM D130 at 150 ° C

 * deposit content too high to be measured

 It is found that the compositions 7 to 9 have a very satisfactory extreme-pressure level. The compositions 7 and 8 give a deterioration stage of 12, the composition 9 gives a deterioration stage of 10. These results are comparable (and better for the compositions 7 and 8) to the results obtained with a reference oil H which has a deterioration stage of 9. This reference oil H comprises 72% by weight of Group I base oil, relative to the weight of oil, 11% by weight of polymer of polymethacrylate type, 8% by weight of PAO , 8% by weight of a package comprising a zinc dialkyldithiophosphate, a dibutyl phosphite, an aryl phosphite and a diphenylamine as an antioxidant. Lubricating compositions 7 to 9 therefore have a better extreme-pressure behavior than this reference oil H since their failure occurs at higher loads.

 Similarly, the lubricant compositions 7 to 9 and especially the composition 9 are insensitive to corrosion (copper or steel) and oxidation.

Example 3

 Lubricant control compositions 10 to 15 are then prepared from a PAO type IV group base oil having a viscosity at 100 ° C. of 6 cSt according to ASTDM D445 and a viscosity number of 125. according to ASTM 2270,

 a dithiocarbamate which is a mixture of zinc diamyldithiocarbamate and diamylamino diamyldithiocarbamate. This mixture is identical to that used in Example 1,

a phosphite P ₂ which is triphenyl phosphite,

a sulfur olefin known for its extreme pressure properties Additin ^® RC 2545. Table V - Mass Composition (%) of Lubricating Compositions 1 and 10 to

15

 The wear and extreme-pressure properties of these lubricant compositions 10 to 15 are then measured.

Table VI - Properties of Lubricating Compositions 10 to 15

¹ Test 4B (4 balls) wear D55 1078

² Test 4B (4 balls) EP (Extreme Pressure) D55 1136

Additin ^® RC 2545 is an extreme-pressure additive, it has the same function as the compound comprising a dithiophosphate group used in the compositions according to the invention.

 However, it is found that the combination of a dithiocarbamate, a phosphite with a sulfur olefin rather than a dithiophosphate does not simultaneously achieve good anti-wear and extreme-pressure properties.

Thus, when at least one compound of different chemical structure is chosen from one of the compounds constituting the lubricating composition according to the invention but having the same function (therefore a compound belonging to another family of additives), no simultaneous improvement of the three anti-wear, extreme pressure and friction properties is observed.

Example 4

 The comparative lubricating composition 16 is prepared on the basis of the composition according to the invention 7 above in which the mixture of metallic dithiocarbamate and amine dithiocarbamate (Vanlube EZ) is replaced by a zinc diamyl dithiocarbamate (Vanlube AZ). .

 Table VII - Mass Composition of Lubricating Compositions 7 and 16

Table VIII - Properties of Lubricating Compositions 7 and 16

¹ Test 4B (4 balls) wear D55 1078

⁴ CEC L84 (A / 16,6R / 120)

The results show that the combination of a metal dithiocarbamate of formula (1-e) and of an amine dithiocarbamate of formula (Ic) makes it possible to very significantly improve the anti-seizing properties of a lubricating composition, while having anti-wear properties quite satisfactory. It should be noted that the mere presence of a metal dithiocarbamate of formula (I-e) in a lubricant composition does not provide good anti-seizure properties.

Claims

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 and at least one compound comprising a dithiophosphate group, the compound comprising a dithiocarbamate group being a mixture:  At least one amine dithiocarbamate of general formula (I-c)

in which - R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, - Rio, Ru and R12 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 Rio, Ru and R ₁₂ is not a hydrogen atom, and  At least one metal dithiocarbamate of general formula (1-e),

wherein R ₁₇ and R ₈ represent independently of the other hydrocarbon groups, optionally substituted, comprising 1 to 30 carbon atoms, M represents a metal cation and n is the valence of this metal cation. A lubricating composition according to claim 1 wherein the compound comprising a dithiocarbamate group is a mixture:  At least one amine dithiocarbamate of general formula (I-c)

in which - R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, - Rio, Ru and R12 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 Rio, Ru and R ₁₂ is not a hydrogen atom, and At least one metal dithiocarbamate of general formula (I-e-2),

wherein R ₁₇ and R ₈ independently of one another linear alkyl hydrocarbon groups. The composition of claim 2 wherein R ₁₇ and R ₈ independently of one another linear alkyl groups comprising from 5 to 12 carbon atoms.  Lubricating composition according to any one of claims 1 to 3 comprising from 0.1 to 5% by weight of compounds 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%, even more preferably from 0.5 to 1%.  A composition according to any one of claims 1 to 4 comprising from 0.1 to 3% by weight of the mixture of amine dithiocarbamate of formula (1c) and of metal dithiocarbamate of formula (I-e), preferably from 0.1 to 2% by weight, advantageously from 0.5 to 2% by weight, relative to the weight of the composition.  A lubricating composition according to any one of claims 1 to 5 wherein the compound comprising a phosphite group is selected from phosphite monoesters, phosphite diesters or phosphite triesters, alone or in admixture. A lubricating composition according to claim 6 wherein the phosphite monoester has the general formula (Ia) in its alcohol and / or ketone form, wherein R ₁₉ represents an optionally substituted hydrocarbon group of 1 to 30 carbon atoms:

 form alcohol form ketone The lubricating composition of claim 6 wherein the phosphite diester has the general formula (1 lb) in its alcohol and / or ketone form, wherein R ₂₀ and R ₂ i independently of one another represent hydrocarbon compounds, optionally substituted, of 1 to 30 carbon atoms:

 form alcohol form ketone Lubricating composition according to claim 6 wherein the phosphite triester has the general formula (II-c) wherein R _{22, 2} 3 and R ₂₄ each independently of the other hydrocarbon groups, optionally substituted, containing 1 at 30 carbon atoms:

Lubricating composition according to any one of claims 1 to 9 comprising from 0.1 to 5% by weight of compound comprising a phosphite 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 lubricant composition according to any one of claims 1 to 10 wherein the compound comprising a dithiophosphate moiety is selected from the group consisting of ammonium dithiophosphates, amine dithiophosphates, ester dithiophosphates and metal dithiophosphates taken alone or in mixture. A lubricating composition according to claim 11 wherein the ammonium dithiophosphate has the general formula (III-a), wherein R ₂₅ and R ₂₆ independently of one another represent hydrocarbon groups, optionally substituted, comprising from 1 to 30 carbon atoms: R ₂₅ 0  NH4 (Ill-a) R ₂₆ O 13. A lubricating composition according to claim 11 wherein the amine dithiophosphate has the general formula (III-b), wherein R ₂₇ and R ₂ 8 are independently one of the other hydrocarbon groups, optionally substituted, comprising from 1 to 30 carbon atoms, R ₂₉ , R ₃₀ and R _3i 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 R ₂₉ , R ₃₀ and R _3i is not a hydrogen atom:

The lubricating composition of claim 11 wherein the ester dithiophosphate has the general formula (III-c), wherein R ₃₃ and R ₃₄ independently of one another represent hydrocarbon groups, optionally substituted, comprising 1 to 30 carbon atoms, R ₃₅ and R ₃₆ represent, independently of one another, hydrocarbon groups comprising from 1 to 18 carbon atoms:

A lubricating composition according to claim 11 wherein the metal dithiophosphate has the general formula (III-d), wherein R ₃₇ and R ₃₈ independently of one another are optionally substituted hydrocarbon groups having 1 to 30 carbon atoms, M is a metal cation and n is the valence of said metal cation:

 16. Lubricating composition according to any one of claims 1 to 15 comprising from 0.1 to 5% by weight of compound comprising a dithiophosphate group, 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 from 0.5 to 1%.  17. Lubricating composition according to any one of claims 1 to 16 further comprising an antioxidant selected from the group consisting of aromatic amines or phenol derivatives.  18. Lubricating composition according to any one of claims 1 to 17 further comprising a dispersant derived from polyisobutene. 19. Lubricating composition according to any one of claims 1 to 18 further comprising a polymer of polymethacrylate type. 20. Lubricating composition according to any one of claims 1 to 19 having a kinematic viscosity at 100 ° C according to ASTM D445 of between 4 and 40 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 20 for lubricating transmissions such as gearboxes, axles, preferably manual gearboxes of motor vehicles. Use of a lubricant composition according to any one of claims 1 to 20 for reducing the fuel consumption of vehicles, particularly motor vehicles.  A method of lubricating transmissions of motor vehicles, said method comprising a step of contacting the lubricant composition according to any one of claims 1 to 20 with the transmissions.  Use of at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group in a base oil to improve the properties of wear, extreme pressure, friction and anti-seizing of a lubricating composition, the compound comprising a dithiocarbamate group being a mixture:  At least one amine dithiocarbamate of general formula (I-c)

in which - R ₈ and R ₉ represent, independently of one another, optionally substituted hydrocarbon groups comprising from 1 to 30 carbon atoms, - Rio, Ru and R12 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 Rio, Ru and R ₁₂ is not a hydrogen atom, and At least one metal dithiocarbamate of general formula (1-e),

wherein R ₁₇ and R ₈ independently of one another hydrocarbon groups, optionally substituted, containing 1 to 30 carbon atoms, M represents a metal cation and n is the valence of the metallic cation.