EP2643441B1 - Engine lubricant composition - Google Patents

Description

Technical area

The present invention relates to engine lubricating compositions, in particular for automobile, gasoline or diesel engines.

Technological background

Lubricating compositions used as motor oil conventionally comprise from 50 to 90% of base oils, which may be of mineral, synthetic or natural origin, and additives. These additives are typically detergents, dispersants, antioxidants, viscosity index (VI) improving polymers, friction modifiers, pour point depressants, defoamers, etc.

The synthetic bases are for example polyalphaolefins, GTL bases obtained for example by Fischer Tropsch processes, or certain esters.

Another category of synthetic base oils is polyalkylene glycols (PAG). These latter bases are for example obtained by polymerization or copolymerization of alkylene oxides, preferably comprising between 2 and 8 carbon atoms. Methods for producing PAG bases are for example described in the applications WO2009 / 134716 and WO2009 / 134638 .

The use of PAG bases in motor oils, especially for automotive engines, has a certain number of interests, in particular because of their good tribological and rheological properties, but also because they are polar bases.

They are therefore likely, on the one hand, to solubilize certain additives necessary for the formulation of a motor oil, which would make these additives effective at lower levels, resulting in an economic gain. They are also likely to solubilize solid contaminants that form during the use of the oil in the engine, resulting in a gain in engine cleanliness.

However, the use of these bases PAG engine lubricant faces a difficulty. Their Noack volatility, measured according to the CEC L 40-93 standard, is very high, which does not allow their incorporation into engine oil formulations, especially in large quantities, and even less as exclusive base oils.

Another difficulty comes from the low solubility of PAG bases in oily compounds, especially other base oils, which makes them unsuitable for use in the engine oil formula.

PAGs are mainly known for their use as base fluids in compressor oils in refrigerant systems. However, the state of the The technique contains some examples of other uses of PAGs, for example in motor oils, for example automobile engines or marine engines.

Requirement WO2009 / 134716 discloses a motor vehicle oil comprising at least one polyalkylene glycol base oil adapted for use in a motor vehicle, combined with an additive package comprising derivatives of aspartic acid, and optionally, antiwear additives, anti-corrosion, antioxidants, friction modifiers, defoamers. No mention is made of the presence of detergent additives in said compositions.

Requirement WO2009 / 134638 discloses a lubricating composition for an internal combustion engine comprising polyalkylene glycols obtained by copolymerization of ethylene oxide and alkylene oxide having up to 12 carbon atoms, comprising between 1 and 50 alkylene oxide units, and optionally an improving polymer of VI. No mention is made of other additives present in the compositions disclosed.

Requirement FR 2817874 discloses functional fluids for automobiles, especially for automotive engines, comprising polyalkylene glycol bases and a reducing agent, which may be urea. These PAGs are in particular obtained from ethylene oxide and propylene oxide. No specific mention is made of other PAG bases or other additives used in combination with PAG bases.

The patent US 5,885,555 discloses a composition for the formulation of dentifrices comprising polyalkylene glycol and methyl salicylate, called "wintergreen". This latter compound is in no way similar to the salicylate detergents used in lubricating compositions, for example in motor oils, where the benzene nucleus of salicylic acid comprises hydrocarbon substituents with sufficiently long chains to constitute the lipophilic part of the detergent.

Requirement EP 1990400 discloses lubricating compositions for transmissions in marine applications, comprising a base oil which can be a synthetic or natural oil. The synthetic oils may be polyalphaolefins (PAO), various esters of (di) carboxylic acids and alcohols or polyols, alkylbenzene bases, polysilicones, polymeric or copolymeric olefins, polyphenols, diphenyl etheralkyls, diphenylsulphidealalkyls, polyalkylene glycols, FischerTropsch bases. These compositions may also comprise at least one metal detergent, which may be chosen from sulphonates, phenates, sulfurized phenates and salicylates. No specific combination of PAG bases with salicylates is disclosed. These compositions for marine transmissions have good water emulsification properties as well as anti-wear properties.

Requirement JP 2007 204451 discloses a polyalkylene glycol which is a tetraether obtained by polymerization of propylene oxide, as well as a diether, for use as a base oil in lubricating compositions, especially for motor oils, and in the presence of certain additives, especially detergents. The disclosed tetraethers, however, have a relatively low molecular weight, and a low kinematic viscosity at 100 ° C. Their use in engine oil formulations therefore requires their use in combination with other base oils; these tetraethers contain only propylene oxide units, which does not give them a high solubility in oils. Furthermore, the solubilization or the suspension in these tetraether bases of additives having a lipophilic portion, such as for example detergents, may pose a problem. The diether is when it consists of 3 long carbon chains (C6 to C14), delimited by two ether functions. The two oxygens of ether functions are distant from 5 carbon atoms. These bases are therefore not polyalkylene glycol, where, by nature, the oxygen atoms are distant from 2 carbon atoms, which corresponds to the attack of the epoxy function of the alkylene oxides during the polymerization. It is expected that their behavior, especially in terms of polarity, will not offer the same benefits as the PAG engine formula.

US 2620302 discloses an engine lubricating composition comprising 1,2-polypropylene glycol, a mineral oil, 1 to 10% of a metal phenate and 0.1 to 1% of zinc dithiocarbamate.

There is therefore a need for lubricating compositions comprising a significant part of PAG bases, which may comprise so-called oily or lipophilic compounds miscible with said PAG bases, and whose Noack volatility is compatible with use as a motor oil.

For engine lubricants, the Noack volatility, measured according to the CEC L 40-93 standard is typically less than 15%, preferably less than 13%. It is typically between 8 and 15%, or between 10 and 13%.

Surprisingly, the Applicant has found that the Noack volatility of some PAG bases, which are otherwise suitable for use in motor oil, is greatly reduced when combined with certain specific additives.

Without wishing to be bound by any theory, it seems that these additives play a role either on the inhibition of the formation of volatile degradation products of PAG, when these bases are subjected to Noack volatility analysis conditions, or on the stabilization of these degradation products in the oil matrix.

The present invention therefore relates to lubricating compositions comprising these specific combinations of PAG bases and additives, as well as to their use as motor oil, especially motor vehicles.

The present invention also relates to the use of these additives, or packages of additives containing them, in engine oil formulations comprising PAG bases.

Finally, the present invention also relates to the use of these additives, or packages of additives containing them, to reduce the Noack volatility of PAG bases measured according to CEC standard L 40-93.

Summary of the invention

1. (a) une ou plusieurs huiles de base polyalkylène glycol, obtenues par polymérisation ou copolymérisation d'oxydes d'alkylène comprenant de 3 à 8 atomes de carbone, dont au moins un oxyde de butylène,
2. (b) au moins un détergent choisi parmi les salicylates ou les phénates ;

et où la ou les huiles de base polyalkylène glycol (a) sont obtenues par réaction d'au moins un alcool comprenant de 8 à 20 atomes de carbone et d'un mélange d'oxyde de butylène et d'oxyde de propylène, ledit mélange ayant un ratio massique oxyde de butylène sur oxyde de propylène compris entre 3 :1 et 1 :3,
la quantité de détergent phénates et/ou salicylates inclus dans la composition lubrifiante étant comprise entre 0,2 et 2% en masse.An object of the invention is a lubricating composition comprising

1. (a) one or more polyalkylene glycol base oils, obtained by polymerization or copolymerization of alkylene oxides comprising from 3 to 8 carbon atoms, of which at least one butylene oxide,
2. (b) at least one detergent selected from salicylates or phenates;

and wherein the polyalkylene glycol base oil (s) are obtained by reaction of at least one alcohol comprising 8 to 20 carbon atoms and a mixture of butylene oxide and propylene oxide, said mixture having a weight ratio of butylene oxide to propylene oxide of between 3: 1 and 1: 3,
the amount of detergent phenates and / or salicylates included in the lubricating composition being between 0.2 and 2% by weight.

According to one embodiment of the composition according to the invention, the polyalkylene glycol base oil (s) is (are) such that the alcohol (s) making it possible to obtain them comprise from 8 to 12 carbon atoms.

According to one embodiment of the composition according to the invention, the polyalkylene glycol base oil (s) (a) are such that the alcohol (s) making it possible to obtain them are chosen from monoalcohols, preferentially from 2-ethylhexanol and / or decanol, preferentially decanol.

According to one embodiment of the composition according to the invention, the polyalkyleneglycol base oil (s) (a) have a carbon to oxygen mass ratio of at least 3: 1, preferably between 3: 1 and 6: 1.

According to one embodiment, the Noack volatility of the composition according to the invention, measured according to the standard CEC L 40-93 is less than 15%, preferably less than 13%.

According to one embodiment of the composition according to the invention, the base or bases (a) have a molar mass measured according to the ASTM D2502 standard of between 300 and 1000, preferably between 350 and 600 grams per mole.

According to one embodiment of the composition according to the invention, the kinematic viscosity of the polyalkylene glycol bases at 100 ° C., measured according to the ASTM D445 standard, is between 1 and 12 cSt, preferentially between 3 and 7, preferentially between 3, 5 and 6, 5 cSt.

According to one embodiment of the composition according to the invention, the polyalkylene glycol base oil (s) (a) is the major component.

According to one embodiment of the invention, the composition comprises from 20 to 90%, preferably from 25 to 85% of polyalkylene glycol base oil (s) (a).

According to one embodiment of the invention, the composition comprises at least one salicylate as detergent (b).

According to one embodiment of the invention, the composition is free of sulfonate detergent.

• (c) au moins un dithiocarbamate à titre d'additif antiusure.

According to an embodiment of the invention further comprising:

• (c) at least one dithiocarbamate as an antiwear additive.

According to one embodiment of the invention, the composition is free of anti-wear additive of the dithiophosphate type, in particular zinc dithiophosphate.

According to one embodiment of the invention, the composition further comprises an amino antioxidant and / or a phenolic antioxidant.

Another subject of the invention relates to the use of a lubricating composition as defined above as engine oil, preferably as an engine oil for motor vehicles, gasoline or diesel.

• au moins un détergent choisi parmi les salicylates ou les phénates, préférentiellement les salicylates,
• au moins un anti usure de type dithiocarbamate,
• au moins un antioxydant aminé ou phénolique,

comme paquet d'additifs pour lubrifiant moteur comprenant des bases polyalkylèneglycol obtenues par polymérisation ou copolymérisation d'oxydes d'alkylène comprenant de 3 à 8 atomes de carbone, dont au moins un oxyde de butylène.Still another object of the invention is the use of an additive package comprising:

• at least one detergent chosen from salicylates or phenates, preferentially salicylates,
• at least one anti-wear of the dithiocarbamate type,
• at least one amino or phenolic antioxidant,

as an engine lubricant additive package comprising polyalkylene glycol bases obtained by polymerization or copolymerization of alkylene oxides comprising from 3 to 8 carbon atoms, of which at least one butylene oxide.

According to a preferred embodiment of the use of the additive package, the polyalkylene glycol bases are the polyalkylene glycol bases (a) as defined above.

According to a preferred embodiment of the use of the additive package, it is free of anti-wear additives of the dithiophosphate type, in particular zinc dithiophosphate.

According to a preferred embodiment of the use of the additive package, it is free of sulfonate detergents.

According to a preferred embodiment of the use of the additive package, the engine lubricant mainly comprises the polyalkylene glycol bases (a) as defined above.

According to a preferred embodiment of the use of the additive package, the engine lubricant exclusively comprises the polyalkylene glycol bases (a) as defined previously as base oils.

According to a preferred embodiment of the use of the additive package, the engine lubricant comprises from 20 to 90%, preferably from 25 to 85% of polyalkylene glycol base oil (s) as defined above.

Another subject of the invention also relates to the use of at least one additive chosen from salicylates and phenates, in order to reduce the Noack volatility measured according to the CEC standard L 40-93, base oils of polyalkylene glycol type, obtained from alkylene oxides comprising from 3 to 8 carbon atoms, of which at least one butylene oxide, preferably wherein the polyalkylene glycol bases are as defined above. There is also described a method of lubricating an engine comprising the use of the lubricant composition as defined above.

According to this method of lubrication the engine is a motor for motor vehicles, preferably gasoline or diesel.

• au moins un détergent choisi parmi les salicylates ou les phénates, préférentiellement les salicylates,
• au moins un anti usure de type dithiocarbamate,
• au moins un antioxydant aminé ou phénolique,

There is also described a package of additives for use in polyalkylene glycol bases obtained by polymerization or copolymerization of alkylene oxides comprising from 3 to 8 carbon atoms, preferably at least one butylene oxide, said package of additives comprising

• at least one detergent chosen from salicylates or phenates, preferentially salicylates,
• at least one anti-wear of the dithiocarbamate type,
• at least one amino or phenolic antioxidant,

It is also described a method for reducing the Noack volatility, measured according to the CEC standard L 40-93, of a polyalkylene glycol base oil obtained from alkylene oxides comprising from 3 to 8 carbon atoms. at least one butylene oxide, preferably wherein the polyalkylene glycol bases (a) are as defined above, wherein at least one additive is added to said polyalkylene glycol base oil, said additive being selected from salicylates , phenates, dithiocarbamates, amine or phenolic antioxidants, preferably from salicylates or phenates.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION Polyalkylene glycol bases (a)

The polyalkylene glycol bases (a) compositions according to the invention have properties suitable for use in a motor oil. These are polymers or copolymers (statistics or blocks) of alkylene oxides, for example prepared according to the known methods described in the application WO 2009/134716 on page 2 line 26 to page 4 line 12, for example by etching an alcohol initiator on the epoxy bond of an alkylene oxide and propagating the reaction.

où Y₁ et Y₂ sont, indépendamment l'un de l'autre, l'hydrogène, ou un groupe hydrocarboné, par exemple un groupe alkyl ou alkylphenyl, ayant entre 1 et 30 atomes de carbone, n représente un entier supérieur ou égal à 2, préférentiellement inférieur à 60, préférentiellement compris entre 5 et 30, préférentiellement compris entre 7 et 15, x représente un ou plusieurs entiers entre 1 et n, Les groupements R_2x-1 et R_2x sont, indépendamment les uns des autres, l'hydrogène, ou des radicaux hydrocarbonés, comprenant entre 1 et 6 atomes de carbone, préférentiellement alkyl, et R_2x est préférentiellement l'hydrogène, La somme des nombres d'atomes de carbone de R_2x-1 et R_2x est comprise entre 1 et 6.
Pour au moins une valeur de x, la somme des nombres d'atomes de carbone de R_2x-1 et R_2x est égale à 4.The polyalkylene glycol (PAG) bases of the compositions according to the invention correspond to the general formula (A):

where Y ₁ and Y ₂ are, independently of one another, hydrogen, or a hydrocarbon group, for example an alkyl or alkylphenyl group, having 1 to 30 carbon atoms, n represents an integer greater than or equal to at 2, preferably less than 60, preferably between 5 and 30, preferably between 7 and 15, x represents one or more integers between 1 and n, the groups R _2x-1 and R _2x are, independently of one another, hydrogen, or hydrocarbon radicals, comprising between 1 and 6 carbon atoms, preferably alkyl, and R _2x is preferably hydrogen, the sum of the carbon number of R _2x-1 and R _2x is between 1 and 6.
For at least one value of x, the sum of the carbon number of R _2x-1 and R _2x is equal to 4.

The alkylene oxides used for the PAG bases of the compositions according to the invention contain between 3 and 8 carbon atoms, of which at least one butylene oxide, the said butylene oxide being 1,2-butylene oxide or 2, Butylene 3-oxide, preferably 1,2-butylene oxide.

Indeed, the PAG obtained (in part) from ethylene oxide do not have a sufficient lipophilic character to be used in engine oil formulations. In particular, they can not be used in combination with other mineral, synthetic or natural base oils. Neutral or overbased detergents, which are essential for the formulation of lubricants which guarantee engine cleanliness, can not be solubilized or suspended in these PAG bases obtained (partly) from ethylene oxide.

The use of alkylene oxides comprising more than 8 carbon atoms is also not desired because, to produce bases having the molar mass and therefore the targeted viscosimetric grade for the motor applications, then there will be a number of reduced monomers (n low in formula (A) above), with long R2x-1 and R2x side chains. This adversely affects the overall linear character of the PAG molecule and leads to viscosity indices (VI) that are too low for engine oil application.

Preferably, their viscosity index VI (measured according to standard NFT 60136) is greater than 100, preferably greater than 120.

So as to give them a sufficient lipophilic character, and therefore good solubility in other synthetic base oils, mineral or natural base oils, and good compatibility with certain essential additives for motor oils, such as detergents, bases PAG (a) compositions according to the invention are obtained from alkylene oxides comprising at least one butylene oxide.

According to the invention, the butylene oxide (BO) and propylene oxide (PO) copolymers are used because they have both the good tribological and rheological properties of the PAG containing ethylene oxide units and / or polypropylene, and good solubility in conventional mineral, synthetic, and natural bases, and other oily compounds.

Requirement WO2011 / 011656 , paragraphs [011] to [014] describes the mode of preparation, characteristics, and properties (especially of solubility and miscibility in the base oils) of such PAG bases butylene oxide / propylene oxide copolymer.

These bases are prepared conventionally, by reaction of one or more alcohols with a mixture of butylene oxide and propylene oxide.

In order to give PAGs good solubility and good miscibility in mineral, synthetic and natural base oils, PAGs prepared with a mixture of butylene oxide and oxide are used in the compositions according to the invention. propylene wherein the weight ratio of butylene oxide to propylene oxide is from 3: 1 to 1: 3. PAG bases prepared with a mixture where this ratio is between 3: 1 and 1: 1 are particularly well miscible and soluble in the other base oils, including Group IV synthetic oils.

(Polyalphaolefins).

According to a preferred embodiment, the PAG bases of the compositions according to the invention are prepared from alcohol containing from 8 to 12 carbon atoms. 2-ethylhexanol and dodecanol, alone or in a mixture, and in particular dodecanol, are particularly preferred since the PAG bases prepared from these alcohols have very low traction coefficients.

According to a preferred embodiment, the PAG bases of the compositions according to the invention are such that their molar carbon to oxygen ratio is greater than 3: 1, preferably between 3: 1 and 6: 1. This gives said PAG bases polarity and viscosity index properties particularly suitable for use in motor oil.

The molar mass, measured according to the ASTM D2502 standard, of the PAG bases of the compositions according to the invention is preferably between 300 and 1000 grams per mole (g / mol), preferably between 350 and 600 g / mol (that is why they contain a limited number of alkylene oxide units n as described above in formula (A)).

This gives them kinematic viscosities at 100 ° C. (KV100) generally of between 1 and 2 cSt and 12 cSt at 100 ° C., preferably between 3 and 7 cSt, preferentially between 3.5 and 6.5 cSt, or between 4 and 4 cSt. 6 cSt or between 3.5 and 4.5 cSt. The KV100 of the compositions is measured according to ASTM D445.

The PAG bases are preferably used as light bases in the automotive engine lubricating compositions according to the invention, where they are preferably combined with VI viscosity index improving polymers and / or other heavier bases.

The use of light PAG (a) bases (KV100 approximately between 2 and 6.5 cSt) is preferably chosen in the compositions according to the invention, in order to be able to more easily formulate cold-grade 5W or OW multigrade oils according to the classification. SAEJ300 because the heavier PAG (a) bases have cold properties (high CCS) which do not easily reach these grades.

The PAG (a) bases, in particular those with KV100 values between 3.5 and 4.5 cSt, of the order of 4 cSt, have Noack volatilities according to the CEC standard L 40-93 of the order of 35 to 40%, which is very high, and can not be caught up in the formula with improving polymers of viscosity index VI or other less volatile bases.

On the other hand, when they are combined with certain additives in the lubricating compositions according to the invention, their volatility is greatly reduced and is typically between 15 and 20%, which is the order of magnitude of the mineral, synthetic or natural bases. typically used in engine oil formulations. This level of volatility of the bases makes it possible to formulate finished motor lubricants having a volatility of between 10 and 15% by mixing with VI viscosity index improving polymers and possibly other heavier bases, which is compatible with the specifications of this type of products.

The lubricant compositions according to the invention preferentially have a Noack volatility, measured according to the CEC L 40-93 standard, of less than 15%, preferably less than 13%. It is typically between 8 and 15%, or between 10 and 13%.

Preferably, in the compositions according to the invention, the base (s) PAG (a) is the majority base (s). By this is meant that the weight percentage of the base PAG (a), or the mass percentage of the cumulative PAG (a) bases, is greater than the mass percentage of each of the other bases present in the compositions according to the invention; the percentages by weight being expressed relative to the total weight of lubricating composition.

Preferably, in the compositions according to the invention, the base (s) PAG (a) is the (the) component (s) majority (s). By this is meant that the weight percentage of the base PAG (a), or the mass percentage of the cumulative PAG (a) bases, is greater than the mass percentage of each of the other components present in the compositions. according to the invention; the percentages by weight being expressed relative to the total weight of lubricating composition.

According to one embodiment, in the compositions according to the invention, the base or bases PAG (a) represent between 20% and 90% by weight, preferably between 25% and 85% by weight, preferably between 30 and 80% by weight. or between 50 and 75% by weight of the lubricating compositions according to the invention.

Detergents (b), Salicylates and Phenates

The detergents used in the lubricant compositions according to the present invention are well known to those skilled in the art.

The detergents commonly used in the formulation of lubricating compositions are typically anionic compounds comprising a long lipophilic hydrocarbon chain (typically comprising at least 9, preferably at least 12 carbon atoms) and a hydrophilic head.

The associated cation is typically a metal cation of an alkali metal, preferably lithium, sodium or potassium.

The detergents (b) of the compositions according to the invention are chosen from alkali metal or alkaline-earth metal salts of the salicylate and phenate type.

These metal salts may contain the metal in an approximately stoichiometric amount. In this case, we speak of non-overbased or "neutral" detergents, although they also bring some basicity. These "neutral" detergents typically have a BN, measured according to ASTM D2896, less than 150 mg KOH / g, or less than 100, or even less than 80 mg KOH / g.

When the metal is in excess (in an amount greater than the stoichiometric amount), we are dealing with so-called overbased detergents. Their BN is high, greater than 150 mg KOH / g, typically between 200 and 700 mg KOH / g, generally between 250 and 450 mg KOH / g.

The excess metal providing the overbased detergent character is in the form of oil insoluble metal salts, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate. The overbased detergents are thus in the form of micelles composed of insoluble metal salts maintained in suspension in the lubricating composition by the detergents in the form of oil-soluble metal salts.

The lubricating compositions according to the invention contain at least one salicylate detergent or at least one alkali or alkaline earth metal phenate detergent, neutral or overbased with the above-mentioned oil-insoluble metal salts. According to one embodiment, they contain at least one salicylate detergent and at least one phenate detergent.

Preferably, the amounts of detergents included in the lubricant compositions according to the invention are adjusted so that the BN of said compositions, measured according to the ASTM D2896 standard, is between 3 and 12 mg of KOH per gram of lubricant, preferentially understood. between 5 and 10, preferably between 6 and 9 mg of KOH per gram of lubricant.

Typically, the amount of phenate and / or salicylate detergents included in the lubricating compositions according to the invention is between 0.2 and 2%, preferably between 0.5 and 2% by weight.

où X₁, X₂, X₃, X₄, X₅ sont soit l'hydrogène, soit des radicaux hydrocarbonés, préférentiellement alkyl, ou alkylaryl, ou arylalkyl, et au moins un des groupes X₁, X₂, X₃, X₄, X₅ est un radical hydrocarboné ayant suffisamment d'atomes de carbone (typiquement au moins environ 9 atomes de carbones, préférentiellement au moins 12 atomes de carbones), pour conférer au salicylate un caractère soluble dans l'huile, et M est un métal alcalin.Typically, the salicylates and phenates used as detergents (b) in the lubricating compositions according to the invention are prepared from salicylic acid and phenol derivatives corresponding respectively to formulas (I) and (II) below:

where X ₁ , X ₂ , X ₃ , X ₄ , X ₅ are either hydrogen, or hydrocarbon radicals, preferably alkyl, or alkylaryl, or arylalkyl, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , X ₅ is a hydrocarbon radical having sufficient carbon atoms (typically at least about 9 carbon atoms, preferably at least 12 carbon atoms), to give the salicylate an oil-soluble character, and M is an alkali metal.

One of the groups X ₁ to X ₅ may for example be an alkyl group, linear or branched comprising at least 9 carbon atoms, preferably between 10 and 160, preferably between 12 and 40, preferably between 14 and 28 carbon atoms. According to one embodiment, at least one of the groups X ₁ to X ₅ is a linear alkyl comprising at least 9 carbon atoms, preferably between 10 and 160, preferably between 12 and 40, preferentially between 14 and 28 atoms or between 18 and 24 carbon atoms.

These detergents may be neutral or overbased with oil-insoluble alkali metal salts such as carbonates, hydroxides, oxalates, acetates, glutamates.

The detergents (b) of the compositions according to the invention may be salicylates, neutral or overbased, corresponding to formulas (III), (IV), (V), below, where X ₁ , X ₂ , X ₃ , X ₄ , X ₅ are as defined above, and X ₆ and X ₇ also have the same meaning, M ₁ is an alkali metal, preferably selected from sodium, potassium, lithium, and M ₂ is an alkaline earth metal, preferably selected among calcium or magnesium.

The detergents of formula (III) and the methods for producing them are described, for example, in the application EP 1548 089 . The detergents of formula (IV) and (V) and the methods for producing them are for example described in the applications US 6,348,438 , and WO 2004/041767 , and EP 0786 448 . Requirement WO 2004/009747 also describes alkaline earth metal salicylate detergents usable as detergent (b) in the compositions according to the invention.

The detergents (b) of the compositions according to the invention may be phenates, neutral or overbased, corresponding to formulas (VI), (VII), (VIII), below, where X ₁ , X ₂ , X ₃ , X ₄ , X ₅ , X ₆ , X ₇ are as defined above, and X ₈ and X ₉ also have the same meaning, M ₁ is an alkali metal, preferably selected from sodium, potassium, lithium, and M ₂ is an alkaline earth metal, preferably selected from calcium or magnesium.

The detergents of formula (VI) and (VII) and (VIII) and the methods for producing them are for example described in the applications EP 2,055,761 , and EP 0 786 448 .

où X₁ à X₇ sont tels que définis ci-dessus, M₂ et M₃ sont des métaux alcalino terreux, préférentiellement choisis parmi le calcium ou le magnésium.Sulfurized derivatives of the salicylates and phenates described above can also be used as detergents (b). These sulfurized derivatives and methods for producing them are for example described in the applications EP 2,055,761 and EP 0786 448 . This latter application also describes mixed detergents phenates salicylates sulfurized compounds, corresponding to formula (IX), which can also be used as detergents (b) in the compositions according to the invention.

where X ₁ to X ₇ are as defined above, M ₂ and M ₃ are alkaline earth metals, preferably selected from calcium or magnesium.

In the compositions according to the invention, salicylate and phenate detergents (b) may be used alone or as a mixture. They may be present in combination with other detergents known to those skilled in the art, such as for example other carboxylates. However, it is preferable to avoid the presence of sulfonate detergents, which are difficult to solubilize in PAG bases, especially when the PAG base (s) constitute the only base oils of the composition, or when the the PAG bases constitute the main base oil (s) of the composition, or when the PAG base (s) constitute at least 20% by weight of the lubricating composition.

According to one embodiment, and in particular in the latter three cases, the compositions according to the invention are free of sulfonate detergents.

Dithiocarbamates (c) :

The lubricant compositions according to the invention may contain one or more dithiocarbamate additives (c). Dithiocarbamates are well known to those skilled in the art as multifunctional additives for lubricants, providing in particular antiwear properties, but also antioxidant, extreme pressure and friction modifier.

Dithiocarbamates used in the compositions according to the invention are for example described in the applications EP 1 730 107 , WO 2005/007786 , the patent US 4,997,969 .

The compositions according to the invention may also contain molybdenum dithiocarbamates, friction modifier additives for motor oils well known to those skilled in the art.

où X11, X12, X13, X14 sont des chaînes alkyl, comportant préférentiellement de 8 à 13 atomes de carbone.These organometallic friction modifiers molybdenum dithiocarbamate can for example satisfy the formula (XI):

where X11, X12, X13, X14 are alkyl chains, preferably having 8 to 13 carbon atoms.

In the compositions according to the invention, dithiocarbamates (c) may be used alone or as a mixture. They may be present in combination with other antiwear, extreme pressure or friction modifier additives known to those skilled in the art. However, it is preferable to avoid the presence of anti-wear additives of the dithiophosphate type, in particular zinc dithiophosphates, which are difficult to solubilize in the PAG bases, in particular when the PAG base (s) constitute the (the) only base oils. of the composition, or the majority base oil (s), or when the PAG base (s) constitute at least 20% by weight of the lubricating composition.

According to one embodiment, and in particular in the latter three cases, the compositions according to the invention are free from anti-wear of the dithiophosphate type, in particular zinc dithiophosphates.

Amino or phenolic antioxidants (d) :

The lubricant compositions according to the invention may optionally comprise amine or phenolic antioxidants, alone or as a mixture.

These are phenols, or secondary amines, whose amine and phenol function is sterically hindered, well known to those skilled in the art for their antioxidant action in lubricants.

The phenolic antioxidants of the compositions according to the invention are phenols substituted on at least one of their ortho positions, preferably both, with alkyl groups comprising from 1 to 10 carbon atoms, for example methyl, isopropyl or tert-butyl groups, preferentially from 1 to 3 carbon atoms. They can also be used in the form of dimers.

The aminated antioxidants of the compositions according to the invention are secondary amines in which the nitrogen atom is connected to at least one aryl group.

• un groupement phényle, éventuellement substitué, de préférence en para de la fonction amine, par des groupements alkyle ou alkenyle comportant de 1 à 10 atomes de carbone, préférentiellement de 1 à 3 atomes de carbone,
• un groupement naphtyle, éventuellement substitué, par des groupements alkyle ou alkenyle comportant de 1 à 10 atomes de carbone, préférentiellement de 1 à 3 atomes de carbone.

ou bien R8 est un groupement phenyle, et R9 forme avec l'atome d'azote de la fonction amine et le cycle de R8 un hétérocycle en C6, éventuellement substitué par des groupements alkyle.Preferably, they are secondary amines of formula R8-NH-R9, where R8 and R9 are, independently of one another:

• a phenyl group, optionally substituted, preferably para to the amine function, with alkyl or alkenyl groups containing from 1 to 10 carbon atoms, preferably from 1 to 3 carbon atoms,
• a naphthyl group, optionally substituted, with alkyl or alkenyl groups containing from 1 to 10 carbon atoms, preferably from 1 to 3 carbon atoms.

or R8 is a phenyl group, and R9 forms with the nitrogen atom of the amine function and the R8 ring a C6 heterocycle, optionally substituted with alkyl groups.

Other basic oils :

The lubricating compositions according to the present invention may comprise, in combination with the PAG bases (a) described above, one or more other base oils, which may be oils of mineral or synthetic origin 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 as a mixture. Saturated content Sulfur content Viscosity index (VI) Group I Mineral oils <90% > 0.03% 80 ≤ VI <120 Group II Hydrocracked oils ≥ 90% ≤ 0.03% 80 ≤ VI <120 Group III Hydrocracked or hydro-isomerized oils ≥ 90% ≤ 0.03% ≥ 120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

These oils may be oils of vegetable, animal or mineral origin. The mineral base oils of the compositions 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 other base oils of the compositions according to the present invention can also be synthetic oils, such as certain esters of carboxylic acids and of alcohols, GTL bases which can be obtained by hydroisomerization of a Fisher-Tropsch wax, or polyalphaolefins. The polyalphaolefins used as base oils, for example, are obtained from monomers having from 4 to 32 carbon atoms (for example octene, decene), and have a viscosity at 100 ° C of between 1.5 and 15 cSt. Their weight average molecular weight is typically between 250 and 3000.

Preferably, the lubricant compositions according to the present invention have a kinematic viscosity at 100 ° C. of between 5.6 and 16.3 Cst, measured by the ASTM D445 standard (grade SAE 20, 30 and 40), preferably between 9, 3 and 12.5 cSt (grade 30). According to a particularly preferred embodiment, the compositions according to the present invention are grade 5W or OW multigrade oils according to the SAEJ300 classification.

The compositions according to the present invention also preferably have a VI viscosity index greater than 130, preferably greater than 150, preferably greater than 160.

Other additives :

The lubricant compositions according to the invention may also contain any type of additive adapted to their use, in particular as motor oil, preferably a motor vehicle engine.

• des dispersants, comme par exemples succinimides, PIB (polyisobutène) succinimides, Bases de Mannich. Ils assurent le maintien en suspension et l'évacuation des contaminants solides insolubles constitués par les produits secondaires d'oxydation qui se forment lorsque l'huile moteur est en service ;
• des antioxydants qui retardent la dégradation des huiles en service, dégradation qui peut se traduire par la formation de dépôts, la présence de boues, ou une augmentation de la viscosité de l'huile. Ils agissent comme inhibiteurs radicalaires ou destructeurs d'hydroperoxydes. Parmi les antioxydants couramment employés, on trouve les antioxydants de type phénolique, aminés stériquement encombrés. Une autre classe d'antioxydants est celle des composés cuivrés solubles dans l'huile, par exemples les thio- ou dithiophosphates de cuivre, les sels de cuivre et d'acides carboxyliques, les dithiocarbamates, sulphonates, phénates, acétylacétonates de cuivre. Les sels de cuivre I et II, d'acide ou d'anhydride succiniques sont utilisés.
• des additifs antiusure, qui protègent les surfaces en frottement par formation d'un film protecteur adsorbé sur ces surfaces. On trouve dans cette catégorie divers composés phosphorés, soufrés, azotés, chlorés et borés.
• et également des antimousse, des polymères améliorants d'indice de viscosité VI, des abaisseurs de point d'écoulement, des inhibiteurs de corrosion,...

These additives can be added individually, or in the form of additive packages, guaranteeing a certain level of performance to the lubricating compositions, as required, for example by the ACEA (Association of European Automobile Manufacturers). limitatively:

• dispersants, for example succinimides, PIB (polyisobutene) succinimides, Mannich bases. They ensure the suspension and evacuation of insoluble solid contaminants consisting of secondary oxidation products that form when the engine oil is in use;
• antioxidants that delay the degradation of the oils in service, degradation that can result in the formation of deposits, the presence of sludge, or an increase in the viscosity of the oil. They act as free radical inhibitors or destroyers of hydroperoxides. Among the commonly used antioxidants are phenolic antioxidants, sterically hindered amines. Another class of antioxidants is that of oil-soluble copper compounds, for example copper thio- or dithiophosphates, copper and carboxylic acid salts, dithiocarbamates, sulphonates, phenates, acetylacetonates of copper. The copper salts I and II, succinic acid or anhydride are used.
• anti-wear additives, which protect the friction surfaces by forming a protective film adsorbed on these surfaces. This category includes various phosphorus, sulfur, nitrogen, chlorine and boron compounds.
• and also antifoam, viscosity index VI improvers, pour point depressants, corrosion inhibitors, etc.

In the lubricating compositions according to the invention, all the additives, for example those described above, including the detergents (b), the dithiocarbamates (c), the antioxidants (d) are preferably used in the usual mass contents of the formulas for motor oils.

Examples :

The Noack volatility of polyalkylene glycol (PAG) bases alone or in the presence of additives was measured according to CEC standard L 40-93. The mass compositions and Noack volatility of the different samples are given in Table 1 and Table 2 below.

Table 1 provides PAG base oils and minerals, alone or mixed.

A is a polyalkylene glycol base (PAG), obtained from alkylene oxides, in particular butylene oxide, in particular butylene oxide (BO) and propylene oxide (PO), with a mass ratio 50/50 BO / PO, molar mass 388 g / mol according to ASTM D2502, kinematic viscosity at 100 ° C (KV100) of 3,982 mm ² / s according to ASTM D445, viscosity number ( VI) of 118. Its Noack volatility is very high (39.4%), compared to that of a mixture of Group III mineral bases (see table 1, A1, Noack of 11.2%). A base mixture PAG A with mineral bases group III makes it possible to obtain an intermediate Noack volatility (see table 1, A2, Noack of 22%).

Table 2 relates to compositions comprising PAG bases alone or in the presence of additives.

Compositions B1 and B3 are compositions according to the invention containing an additive package which comprises a salicylate detergent, an anti-dithiocarbamate anti-oxidant, an amino antioxidant and a phenolic antioxidant. Their Noack volatility is of the order of magnitude of that of known engine oils.

Composition B1 comprises a mixture of PAG bases and Group III mineral bases comparable to the A2 base mixture.

If we compare the Noack volatility of B1 (14%) to that of A2 (22%), we can see that the presence of additives has made it possible to significantly lower the Noack volatility.

Composition B2 also comprises a mixture of PAG bases and Group III mineral bases comparable to the A2 base mixture. B2 does not include salicylate or phenate additives, and is not according to the invention. B2, on the other hand, comprises a viscosity VI improving polymer.

If we compare the Noack volatility of B2 (21.3%) to that of A2 (22%), we see that the effect of the viscosity index improving polymer VI on the Noack volatility is almost zero.

The lowering of volatility found in B3 (11%) is due to the effect of the package additives and not to the viscosity index VI improving polymer. This effect is reinforced by the addition of a viscous PAO base.

Compositions C to K contain PAG base A combined with various additives.

Compositions F and G are compositions according to the invention. Their Noack volatility is of the order of magnitude of those of light base oils conventionally used in the formulation of engine oils.

The samples H, J, K also have a Noack volatility strongly lower compared to the base A, thanks to the respective presence of dithiocarbamate, antioxidant amine, phenolic antioxidant, and confirm the possibility of using these additives according to the invention to lower the Noack volatility of a PAG base comprising at least one butylene oxide unit.

L is a polyalkylene glycol (PAG) base, obtained from ethylene oxide and propylene oxide, with a molar mass of 388 g / mol, a KV 100 of 3,981 mm ² / s, and a viscosity index of VI 119. Its volatility Noack is very high (37.4%).

The composition M, which contains the base L and a phenolic antioxidant, has its volatility greatly reduced, at a level of the order of magnitude of those of the light base oils conventionally used in the formulation of motor oils.

Sample N demonstrates that base L does not solubilize salicylate detergents.

O is a polyalkylene glycol base (PAG), obtained from propylene oxide (100% PO), with a molecular weight of 750 g / mol, of KV100 6 cSt, with a viscosity index VI 179.

Composition P contains base O and 1% phenate detergent. Sample P demonstrates that the base O which does not contain butylene oxide units, does not solubilize detergents, especially phenates, unlike the base A in sample F.

Composition B5 comprises base O in a motor oil formulation. Again, this sample, B5 shows that the base O does not solubilize the packets of additives traditionally used and / or that the base O is not compatible with the base oils traditionally used.

It is the same for the composition B4 which comprises the base L in a motor oil formulation.

Only the base A in a motor formulation (see sample B3) allows compatibility, solubility with base oils and additives. <b> Table 1, mass percentages and Noack </ b> AT A1 A2 PAG with BO (BO / PO: 50/50) (KV100 = 4 cSt) 100% 38.3% Group III base UCBO4R KV100 = 4.135cSt 77.4% 50.8% Base group III UCBO7R KV100 = 6.918mm ² / s 22.6% 10.9% Noack, CEC standard L 40-93 39.4% 11.2% 22.02% AT B1 B2 B3 VS D E F BOY WUT H I J K The M NOT PAG with butylene oxide BO / PO KV100 = 4 cSt 100% 31.9% 35.6% 30% 99% 99% 49.5% 99% 99% 99% 99% 99% 99% PAG with ethylene oxide EO / PO KV100 = 4 cSt 100% 99% 99% VI Enhancer Polymer 7.1% 6% Base group I KV100 4 cSt 42.3% 47.2% 48.3% Base group III KV100 7 cSt 9.1% 10.1% PAO 4 KV100 4cSt 49.5% Additives package 16.7% 15.7% Dispersant succinimide 1% Amino antioxidant 1% Phenolic antioxidant 1% 1% Sulphonate detergent 1% 1% Phenate detergent 1% Salicylate detergent 1% 1% Anti-wear dithiocarbamate 1% Zinc dithiophosphate antiperspirant 1% Volatility Noack CEC L 40-93 39.4% 14% 21.3% 11% 39% Detergent not soluble in PAG PAO / PAG demixtion 20% 16% 21% Bad solubilization and hot deposits 22% 22% 37.4% 20.9% Detergent not soluble in PAG B4 B5 O P PAG BO / PO KV100 = 4 cSt PAG EO / PO KV100 = 4 cSt 30% PAG PO 100% KV100 = 6 cSt 30% 100% 99% VI Enhancer Polymer 6% 6% Base group I KV100 4 cSt 48.3% 48.3% Base group III KV100 7 cSt PAO 4 KV100 4cSt Additives package 15.7% 15.7% Dispersant succinimide Amino antioxidant Phenolic antioxidant Sulphonate detergent Phenate detergent 1% Salicylate detergent Anti-wear dithiocarbamate Zinc dithiophosphate antiperspirant Volatility Noack CEC L 40-93 Trouble Trouble - Trouble

Claims (14)

1. A lubricant composition comprising:

   (a) one or several polyalkylene glycol base oils, obtained by polymerization or copolymerization of alkylene oxides comprising 3 to 8 carbon atoms, including at least one butylene oxide,

   (b) at least one detergent selected from salicylates or phenates;

   and wherein the polyalkylene glycol base oil(s) (a) are obtained by reacting at least one alcohol comprising from 8 to 20 carbon atoms and a mixture of butylene oxide and propylene oxide, said mixture having a mass ratio of butylene oxide over propylene oxide comprised between 3:1 and 1:3,
   the amount of phenate and/or salicylate detergents included in the lubricant composition being comprised between 0.2 and 2% by mass.
2. The lubricant composition according to claim 1, wherein the mass ratio of butylene oxide over propylene oxide is comprised between 3:1 and 1:1.
3. The composition according to one of claims 1 to 2, wherein the polyalkylene glycol base oil(s) (a) is such that the alcohol(s) with which they may be obtained includes from 8 to 12 carbon atoms.
4. The composition according to one of claims 1 to 3, wherein the polyalkylene glycol base oil(s) (a) are such that the alcohol(s) with which they may be obtained are selected from monoalcohols, preferably from 2-ethylhexanol and/or decanol, preferentially decanol.
5. The composition according to one of claims 1 to 4, wherein the polyalkylene glycol base oil(s) (a) have a molar ratio of carbon over oxygen of at least 3:1, preferentially comprised between 3:1 and 6:1.
6. The lubricant composition according to one of claims 1 to 5, wherein the Noack volatility, measured according to the CEC L 40-93 standard, is less than 15%, preferentially less than 13%.
7. The lubricant composition according to one of claims 1 to 6, wherein the base(s) (a) have a molar mass measured according to the ASTM D2502 standard comprised between 300 and 1,000, preferentially between 350 and 600 grams per mole.
8. The lubricant composition according to one of claims 1 to 7, wherein the kinematic viscosity of the polyalkylene glycol bases at 100 °C, measured according to the ASTM D445 standard, is comprised between 1 and 12 cSt, preferentially between 3 and 7, preferentially between 3.5 and 6.5 cSt.
9. The lubricant composition according to one of claims 1 to 8, comprising from 20 to 90%, preferentially from 25 to 85% of polyalkylene glycol base oil(s) (a).
10. The composition according to one of claims 1 to 9 further comprising: (c) at least one dithiocarbamate as an anti-wear additive.
11. The use of a lubricant composition according to one of claims 1 to 10 as motor oil, preferentially as oil for gasoline or diesel engines of automobile vehicles.
12. The use of an additive package comprising:

    • at least one detergent selected from salicylates or phenates, preferentially salicylates,

    • at least one anti-wear agent of the dithiocarbamate type,

    • at least one amine or phenol antioxidant,

    as an additive package for an engine lubricant comprising polyalkylene glycol bases obtained by polymerization or copolymerization of alkylene oxides comprising from 3 to 8 carbon atoms, including at least one butylene oxide.
13. The use according to claim 12 wherein the polyalkylene glycol bases are the polyalkylene glycol bases (a) of claims 1 to 5.
14. The use of at least one additive selected from salicylates and phenates for reducing the Noack volatility as measured according to the CEC L 40-93 standard, of base oils of a polyalkylene glycol type, obtained from alkylene oxides comprising from 3 to 8 carbon atoms, including at least one butylene oxide, preferably the polyalkylene glycol bases (a) of claims 1 to 5.