Improved grease and novel sulfur-containing functional additive

Abstract

The present invention relates to a grease composition comprising a novel sulfur-containing additive with extreme pressure and / or antiwear properties, in particular homocysteine, cysteine and derivatives thereof. The invention also relates to the use of such a novel sulfur-containing additive, as well as to a method for lubricating a metal or a composite material, comprising contacting said metal or said composite material with a grease comprising said sulfur-containing additive.

Description

Technical Field

[0001] This invention relates to a (lubricating) grease composition comprising a novel sulfur-containing additive having extreme pressure and / or anti-wear properties. The invention also relates to the use of this novel sulfur-containing additive in (lubricating) greases, and further to a method for lubricating metals or composite materials, the method comprising contacting the metal or composite material with a (lubricating) grease comprising the sulfur-containing additive. Background Technology

[0002] For many industrial processes, the known practice is to use fluids or greases to lubricate mechanical systems. These lubricating compositions allow for the limitation of corrosion and wear on mechanical systems, enabling them to remain in good condition for as long as possible.

[0003] Due to its higher viscosity compared to fluids, grease is typically used to lubricate mechanical systems where lubricating fluid cannot be retained or to seal lubrication points in contact with water. They are commonly used to lubricate components of machines, tools, or equipment subjected to high loads and / or high temperatures (where oil evaporates) and / or slow or decelerating movements. Grease has the advantage of remaining at the lubrication point, thus extending the lubrication interval.

[0004] They typically contain one or more oils (called base oils) with at least one thickener dispersed within them to achieve a paste-like texture. They may also contain one or more functional additives to, for example, improve their tribological properties.

[0005] There are two main types of grease:

[0006] - A (lubricating) grease made from metallic soaps dispersed in one or more base oils. The soap molecules then form a network, which can be likened to a sponge trapping the lubricating oil; and

[0007] - Greases that do not contain metal soaps, especially those made from synthetic organic compounds (such as polyureas or sulfonates) or mineral-derived materials (such as bentonite, silica gel, etc.). The latter greases are called "non-melting" because they do not melt at high temperatures, unlike metal soap-based greases, whose melting point (called dropping point) depends on the nature of the soap.

[0008] Regardless of the type of grease, the latter typically contains functional additives to improve its tribological properties and / or improve or provide other properties, such as corrosion protection.

[0009] There is a constant need for greases with improved tribological properties. Therefore, new functional additives are required.

[0010] There is a particular need for multifunctional additives, especially those that are more environmentally friendly and, where possible, bio-based. Additives that are halogen-free and, in particular, chlorine-free are of particular interest. Specifically, greases that do not use or can limit the use of chlorinated paraffins, which are commonly used as extreme pressure additives, are sought.

[0011] The object of the present invention is to provide novel extreme pressure and / or anti-wear additives for grease compositions, preferably novel bifunctional additives that are both extreme pressure and anti-wear.

[0012] One object of the present invention is to provide novel extreme pressure and / or anti-wear additives that are more environmentally friendly and, in particular, bio-based.

[0013] Another object of the present invention is to provide grease compositions with improved tribological properties, particularly with improved extreme pressure and / or anti-wear properties.

[0014] The object of this invention is to provide a grease composition for lubricating industrial machinery systems. Summary of the Invention

[0015] The present invention satisfies all or some of the above objectives.

[0016] The inventors have surprisingly discovered that homocysteine ​​and its derivatives (i.e., sulfur-containing compounds of general formula (I) below) possess dual extreme pressure and anti-wear properties in greases. They can also have anti-corrosion properties, thus potentially having three functions.

[0017] To determine such properties, those skilled in the art may refer to:

[0018] - Standard ASTM D2596-20 describes a test method for measuring the extreme-pressure (EP) properties of lubricating grease (Four-Ball Method); and

[0019] - Standard IP239 (2014) describes a test method for measuring the extreme-pressure and anti-wear properties of lubricating fluids and greases (four ball method European conditions).

[0020] These dual-function anti-wear and extreme pressure additives offer numerous advantages. First, they allow for a reduction in the number of components, thus lowering the cost of (lubricating) greases, while simultaneously improving their recyclability.

[0021] Furthermore, sulfur-containing compounds of general formula (I), and particularly homocysteine, are biodegradable and optionally bio-based, which makes it possible to obtain (lubricating) greases with improved environmental friendliness and durability. In particular, they do not contain halogen atoms.

[0022] Their compatibility with lipid compositions is particularly surprising because these compounds, especially homocysteine, are soluble in water but insoluble or only slightly soluble in fatty substances.

[0023] It has also been found that these sulfur-containing compounds can most specifically improve the anti-wear properties of (lubricating) greases, especially when they are combined with other anti-wear additives, and particularly with zinc dialkyl dithiophosphate and / or zinc diaryl dithiophosphate.

[0024] Therefore, the present invention relates to lipid compositions comprising:

[0025] a) Sulfur-containing compounds or their salts of the following general formula (I):

[0026] R3-X-CH(NR1R2)-(CH2) n -(S) P -Z (I)

[0027] in:

[0028] -Z represents a hydrogen atom or -(CH2). n -CH(NR1R2)-X-R3 group;

[0029] -R1 and R2 may be the same or different, and are selected from: hydrocarbon chains with 1 to 20 carbon atoms and may contain one or more heteroatoms, whether they are hydrogen atoms or saturated or unsaturated; straight-chain, branched or cyclic; aromatic or non-aromatic.

[0030] -X is selected from -C(=O)-, -CH2-, or -CN;

[0031] -R3 is:

[0032] (i) Zero when X represents -CN

[0033] (ii) or hydrogen atom,

[0034] (iii) or -OR a R aIt is a hydrocarbon chain with 1 to 20 carbon atoms and may contain one or more heteroatoms, whether it is saturated or unsaturated, straight-chain, branched or cyclic, aromatic or non-aromatic.

[0035] (iv) or -NR b R c R b and R c They may be the same or different, and are selected from: hydrocarbon chains having 1 to 20 carbon atoms and containing one or more heteroatoms, whether they are hydrogen atoms or saturated or unsaturated; straight-chain, branched or cyclic; aromatic or non-aromatic.

[0036] -n is an integer equal to 1 or 2; and

[0037] -p is an integer from 1 to 8, preferably p equal to 1 or 2;

[0038] The condition is that if Z is a hydrogen atom, then p equals 1;

[0039] b) One or more base oils;

[0040] c) One or more thickeners; and

[0041] d) One or more optional functional additives.

[0042] The present invention also relates to the use of greases according to the invention for lubricating mechanical devices, preferably selected from rolling and sliding bearings, gears, cables, chains, reels, and mechanical devices that do not include sealing systems.

[0043] The present invention relates to the use of sulfur-containing compounds of general formula (I) or salts thereof as anti-wear and / or extreme pressure additives, preferably in greases, more preferably in greases such as those according to the invention.

[0044] The present invention also relates to a method for lubricating metals or composite materials, comprising the step of contacting the metal or composite material with a grease comprising a sulfur-containing compound of general formula (I) or a salt thereof, preferably such as a grease according to the present invention. Detailed Implementation

[0045] The grease, particularly a lubricating grease, according to the invention is preferably used for industrial applications. It can be used to lubricate metals or composite materials.

[0046] It can also be used to lubricate mechanical devices, including rolling and sliding bearings, gears, cables, chains, reels, and mechanical devices that do not contain sealing systems.

[0047] It can be used in many industrial sectors, particularly construction, automotive, steel, mining (e.g., for lubricating conveyor belts) or papermaking.

[0048] The metals discussed are particularly iron and ferrous metals, such as steel (e.g., stainless steel, carbon steel, or low-alloy carbon steel) or cast iron; non-ferrous metals, such as copper, zinc, nickel, aluminum, magnesium, zirconium, cobalt, titanium, and their alloys, such as brass. In composite materials, nickel-sintered tungsten carbide may be mentioned.

[0049] Sulfur-containing compounds of general formula (I):

[0050] In particular, the lipid compositions according to the invention comprise sulfur-containing compounds of the following general formula (I) or salts thereof:

[0051] R3-X-CH(NR1R2)-(CH2) n -(S) P -Z (I)

[0052] in:

[0053] - When p equals 1, Z is a hydrogen atom, or -(CH2). n -CH(NR1R2)-X-R3 group (when p is between 2 and 8);

[0054] -R1 and R2 can be the same or different, selected from: hydrogen atoms or saturated or unsaturated, straight-chain, branched or cyclic, aromatic or non-aromatic hydrocarbon chains having 1 to 20 carbon atoms and may contain one or more heteroatoms.

[0055] -X is selected from -C(=O)-, -CH2-, or -CN;

[0056] -R3 is:

[0057] (i) Zero when X represents -CN

[0058] (ii) or hydrogen atom,

[0059] (iii) or -OR a R a Hydrocarbon chains having 1 to 20 carbon atoms and may contain one or more heteroatoms, and may be straight-chain, branched or cyclic, aromatic or non-aromatic, consisting of hydrogen atoms or saturated or unsaturated hydrocarbons.

[0060] (iv) or -NR b R c R b and R c Same or different, selected from: hydrocarbon chains having 1 to 20 carbon atoms and possibly containing one or more heteroatoms, whether hydrogen atoms are saturated or unsaturated; straight-chain, branched or cyclic; aromatic or non-aromatic.

[0061] -n is an integer equal to 1 or 2; and

[0062] -p is an integer from 1 to 8, preferably p equal to 1 or 2.

[0063] When Z is -(CH2) n When the -CH(NR1R2)-X-R3 group is used, it should be understood that n and the various groups X, R1, R2 and R3 are the same in general formula (I): to obtain symmetrical sulfides, disulfides or polysulfides (see, for example, cystine and homocystine).

[0064] Preferably, the sulfur-containing compound has the following general formula (Ia):

[0065] R3-X-CH(NR1R2)-(CH2) n -SH (Ia)

[0066] R1, R2, R3, X, and n are defined as above.

[0067] The term "heteroatoms" is intended to specifically refer to oxygen, nitrogen, and sulfur.

[0068] Specifically, R1 and R2 are hydrogen atoms.

[0069] Specifically, n equals 2.

[0070] Specifically, p is an integer from 1 to 5, and more preferably p equals 1, 2 or 3.

[0071] In particular, compounds of general formula (I) or (Ia) are preferred, wherein X is -C(=O)- and R3 is -OR. a , where R a As defined above. R a H is preferred.

[0072] As preferred compounds, the following can be mentioned:

[0073] Cysteine ​​of the formula HS-CH2-CH(NH2)-COOH (L-type is CAS 52-90-4, D-type is CAS 921-01-7);

[0074] Cystine of the formula HOOC-CH(NH2)-CH2-SS-CH2-CH(NH2)-COOH (L-type CAS 56-89-3, D-type CAS 349-46-2);

[0075] Homocysteine ​​of the formula HS-(CH2)2-CH(NH2)-COOH (L-type is CAS 6027-13-0, D-type is CAS 6027-14-1);

[0076] Homocysteine ​​of the formula HOOC-CH(NH2)-(CH2)2-SS-(CH2)2-CH(NH2)-COOH (L-type is CAS626-72-2 and D-type is CAS 870-93-9);

[0077] - Trisulfide biscysteine ​​(HOOC-CH(NH2)-CH2-SSS-CH2-CH(NH2)-COOH), tetrasulfide biscysteine, pentasulfide biscysteine; and

[0078] -Dihomocysteine ​​trisulfide (HOOC-CH(NH2)-(CH2)2-SSS-(CH2)2-CH(NH2)-COOH), dihomocysteine ​​tetrasulfide, and dihomocysteine ​​pentasulfide.

[0079] Preferred sulfur-containing compounds according to the present invention are cysteine, cystine, homocysteine, dicysteine ​​trisulfide, dicysteine ​​tetrasulfide, dicysteine ​​pentasulfide, dihomocysteine ​​trisulfide, dihomocysteine ​​tetrasulfide, dihomocysteine ​​pentasulfide and their salts, with homocysteine ​​being preferred.

[0080] The most particularly preferred sulfur-containing compounds according to the present invention are homocysteine, homocysteine, di-homocysteine ​​trisulfide, di-homocysteine ​​tetrasulfide, and di-homocysteine ​​pentasulfide. Homocysteine ​​is the most preferred sulfur-containing compound.

[0081] Homocysteine ​​is particularly well-suited for formulation in lipids: it is uniformly distributed in lipids and does not form crystals. Surprisingly, it also exhibits high extreme pressure properties.

[0082] When referring to sulfur-containing compounds of general formula (I) in this specification, salts of these compounds are included in the description. When using salts of sulfur-containing compounds of general formula (I), basic salts are preferred. In particular, the salt is a metal salt or a quaternary ammonium salt. Preferably, the salt is selected from alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts.

[0083] The term "metal" as used to describe the availability of the metal salt should be understood to specifically refer to metals in columns 1 to 5 of the periodic table (formerly IA to VA), as well as aluminum, tin, and lead. In particular, the metal is selected from: alkali metals, alkaline earth metals, scandium, titanium, zirconium, vanadium, niobium, aluminum, tin, and lead.

[0084] The term "alkali metals" refers to metals corresponding to Group 1 (column 1) of the periodic table. Lithium, sodium, and potassium may be specifically mentioned. The term "alkaline earth metals" should be understood to refer to metals corresponding to Group 2 (column 2) of the periodic table. Magnesium, calcium, strontium, and barium may be specifically mentioned.

[0085] The term "quaternary ammonium" should be understood to specifically refer to ammonium of the following general formula (III):

[0086] + N(R5R6R7R8) (III)

[0087] The groups R5, R6, R7, and R8 may be the same or different, and are independently selected from:

[0088] Hydrogen atom, (C1-C 10 )alkyl, (C6-C 10 )Aryl, (C1-C 10 )alkoxy, polyalkylalkoxy, (C1-C 10 Alcohols and polyols; preferably selected from hydrogen atoms, (C1-C2) 10 )alkyl and (C1-C 10 ) alcohols. The ammonium form of monoethanolamine can be mentioned most specifically. + NH3(CH2CH2OH)), ammonium diethanolamine, ammonium triethanolamine, and ammonium methyldiethanolamine.

[0089] Specifically, the basic salt is selected from homocysteine ​​or homocysteine ​​monoalkali metal, dialkali metal, alkaline earth metal or quaternary ammonium salts, preferably from homocysteine ​​or homocysteine ​​dialkali metal or alkaline earth metal salts.

[0090] The alkaline salt is specifically selected from: monosodium homocysteine, disodium homocysteine; monosodium homocysteine, disodium homocysteine, disodium cystine, disodium homocysteine; monopotassium homocysteine, disodium homocysteine; monopotassium homocysteine, disodium homocysteine, disodium cysteine, and disodium homocysteine. Disodium homocysteine ​​and disodium homocysteine ​​are most particularly preferred.

[0091] The sulfur-containing compound may exist in any enantiomeric form of the L or D type, or in a racemic form other than that. In particular, the L type, a form found in nature, is preferred.

[0092] Sulfur-containing compounds of general formula (I) are typically in solid form. When in powder form, they can be dispersed in base oils. For example, cysteine ​​can be commercially available (e.g., sold by Wacker or Showa Denko).

[0093] In the lipid composition according to the invention, the amount of the sulfur-containing compound of general formula (I) relative to the total weight of the lipid can be between 0.1% by weight and 50% by weight, preferably between 0.1% by weight and 20% by weight, more preferably between 0.1% by weight and 10% by weight, and most particularly between 1% by weight and 7% by weight, for example between 2% by weight and 5% by weight.

[0094] It should be understood that the lipid composition may contain several sulfur-containing compounds as defined above. In this case, the total amount of these sulfur-containing compounds relative to the total weight of the lipid may be between 0.1 wt% and 50 wt%, preferably between 0.1 wt% and 20 wt%, more preferably between 0.1 wt% and 10 wt%, and most particularly between 1 wt% and 7 wt%, for example between 2 wt% and 5 wt%.

[0095] In the grease composition according to the invention, the sulfur-containing compound makes it possible to particularly obtain or improve the extreme pressure and / or anti-wear effects of the grease, preferably both of these effects.

[0096] Base oil:

[0097] The lipid compositions according to the invention comprise one or more oils referred to as "base oils". Base oils may be mineral, synthetic or bio-based (produced from plant or animal biomass) or mixtures thereof.

[0098] Mineral oils and synthetic oils can be selected from groups I through V of the API (American Petroleum Institute) classification. The API classification can be found on the NLGI (National Association of Lubricating Grease Manufacturers, Inc.) website: https: / / www.nlgi.org / grease-glossary / api-groups-iv / . Specifically, mineral oils belong to groups I through III, while synthetic oils belong to groups IV and V.

[0099] The mineral base oils according to the invention include all types of oils obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, and hydroisomerization, or hydrorefining. Particular mention may be made of alkanes, cycloalkanes, and aromatic mineral oils and mixtures thereof.

[0100] The synthetic base oil according to the present invention may be selected from carboxylic acid esters, phosphate esters, silicones, glycols, polybutene, poly-α-olefins (PAO), alkylbenzenes, alkylnaphthalenes and mixtures thereof.

[0101] Base oils can also be bio-based oils, such as esters of alcohols and carboxylic acids, which can be obtained from natural resources, such as sunflower oil, rapeseed oil, palm oil, soybean oil, castor oil, etc.

[0102] Preferably, the composition comprises one or more mineral base oils.

[0103] Preferably, the total amount of base oil in the grease composition according to the invention is at least 50% by weight, preferably at least 70% by weight, relative to the total weight of the composition. In particular, it is from 75% to 95% by weight, preferably from 80% to 90% by weight, relative to the total weight of the grease.

[0104] Thickener:

[0105] The lipid compositions according to the invention comprise one or more thickeners. Thickeners are commonly used in the lipid industry and are known to those skilled in the art. They may be selected from fatty acid metal soaps, synthetic organic thickeners, inorganic thickeners, and mixtures thereof.

[0106] Specifically, the thickener may be selected from fatty acid metal soaps, (poly)urea, sulfonates (especially calcium sulfonate), polyamides, polyimides, polytetrafluoroethylene (PTFE), silica gel, aluminosilicates, modified clays (especially bentonite), graphite, carbon black, boron nitride, and mixtures thereof.

[0107] More specifically, the thickener may be selected from fatty acid metal soaps, (poly)urea, sulfonates (especially calcium sulfonate), polytetrafluoroethylene (PTFE), silica gel, bentonite, graphite and mixtures thereof; preferably selected from fatty acid metal soaps, (poly)urea and sulfonates (especially calcium sulfonate).

[0108] More preferably, the thickener is selected from alkali metal soaps, alkaline earth metal soaps, and (poly)urea.

[0109] Fatty acid metal soaps

[0110] Fatty acid metal soaps are readily available and inexpensive products commonly used in the lipoprotein industry. They can be prepared alone or in situ during lipoprotein production. In the latter case, fatty acids are dissolved in a base oil, and then the desired saponifying agent is added.

[0111] Long-chain fatty acids, typically containing 10 to 28 carbon atoms, preferably 14 to 24 carbon atoms, are preferred. These chains are saturated or unsaturated, linear, branched, or cyclic, and optionally hydroxylated. Examples of long-chain fatty acids include, for instance, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, benzyl acid, oleic acid, linoleic acid, erucic acid, and their hydroxylated derivatives, such as hydroxystearic acid, hydroxybenzyl acid, and hydroxypalmitic acid. 12-Hydroxystearic acid is the most well-known derivative in this category. Hydrogenated fatty acids based on castor oil may also be mentioned.

[0112] These long-chain fatty acids typically come from vegetable oils, such as palm oil, castor oil, rapeseed oil, and sunflower oil, or animal fats (beef tallow, whale oil, etc.).

[0113] Soaps known as simple soaps can be formed using one or more long-chain fatty acids. Soaps known as complex soaps can also be formed by combining one or more long-chain fatty acids with one or more carboxylic acids having short hydrocarbon chains containing up to eight carbon atoms.

[0114] The saponifying agent used in soap preparation can be a metal compound containing alkali metals, alkaline earth metals, titanium, or aluminum. It can be a hydroxide, oxide, or carbonate of these metals. Lithium, sodium, magnesium, calcium, barium, zinc, strontium, lead, titanium, and aluminum are preferred metals, with lithium, sodium, calcium, and aluminum being the most favored.

[0115] Therefore, fatty acid metal soaps as described above can be used, particularly alkali metal soaps, alkaline earth metal soaps, titanium soaps, or aluminum soaps, preferably lithium soaps, sodium soaps, calcium soaps, or aluminum soaps. As mentioned above, the soaps can be simple or complex. It should be understood that the fats according to the invention can contain one or more fatty acid metal soaps. For example, lithium soaps can be combined with calcium soaps.

[0116] Synthetic organic thickeners

[0117] Among the synthetic organic thickeners that can be used in the lipid compositions according to the invention, (poly)urea, sulfonates, and polymeric thickeners may be mentioned. (Poly)urea is particularly preferred according to the invention.

[0118] (poly)urea

[0119] In (poly)urea, urea, diurea, and polyurea, such as triurea, tetraurea, urethane, and mixtures thereof, can be mentioned. (Poly)urea is usually prepared in situ in base oil. Urea is specifically prepared by reacting a monoamine with an isocyanate. The amine:isocyanate molar ratio is typically between 1:1 and 2:1. Diurea is obtained, in particular, by reacting a monoamine with a diisocyanate. Polyurea is specifically obtained by reacting a diamine with a diisocyanate.

[0120] Amines can be selected from aliphatic, alicyclic, and aromatic amines and mixtures thereof. Monoamines or diamines can be used. Monoamines can be selected from pentylamine, hexylamine, heptylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, cyclohexylamine, benzylamine, aniline, p-toluidine, oleylamine, laurylamine, or palmitamine.

[0121] The diamine can be selected from ethylenediamine, propylenediamine, butyldiamine, hexamethylenediamine, octyldiamine, phenyldiamine, toluenediamine, or xylenediamine.

[0122] The isocyanate may be selected from monoisocyanates, diisocyanates, polyisocyanates, and mixtures thereof, preferably from diisocyanates. The isocyanate may be aliphatic or aromatic, preferably aromatic. Among aromatic diisocyanates, the following may be mentioned: phenylene diisocyanate, phenyl diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, diphenylmethylene diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate.

[0123] sulfonates

[0124] Thickeners known as "sulfonates" are typically obtained by neutralizing alkylaryl sulfonic acids or alkenylaryl sulfonic acids with an alkali metal base or an alkaline earth metal base. Preferably, they are calcium sulfonates (also known as "calcium sulfonate soaps"). Sulfonate soaps can be prepared alone or in situ during the production of the ester. For example, the sulfonic acid is mixed into a base oil, and then an alkali metal base or an alkaline earth metal base is added.

[0125] The alkyl or alkenyl group may be straight-chain or branched, and may contain 10 to 24 carbon atoms. The aryl group is particularly selected from benzyl or naphthyl.

[0126] Preferably, the sulfonate thickener is an alkylbenzene sulfonate, more preferably calcium alkylbenzene sulfonate and, for example, calcium dodecylbenzene sulfonate.

[0127] In particular, sulfonates can be highly basic, meaning that the metal is in excess (in an amount greater than the stoichiometric amount relative to the anionic groups of the soap). The excess metal providing the high basicity characteristic is especially in the form of oil-insoluble metal salts, such as carbonates, hydroxides, oxalates, acetates, glutamates, with carbonates being preferred. For example, highly basic calcium sulfonate is calcium sulfonate highly basicized with calcium carbonate.

[0128] polymer thickener

[0129] Polymer thickeners such as polyamide, polyimide, or polytetrafluoroethylene (PTFE) can also be used as thickeners. PTFE is preferred.

[0130] Inorganic thickeners

[0131] Inorganic thickeners are also available, which can be selected from silica gel, aluminosilicates, modified clays such as bentonite, graphite, carbon black, boron nitride, and mixtures thereof. Regarding silica gel, the gelling agent is typically highly dispersible silicic acid (lipophilic silica). These acids are known under various names, particularly by the name "Aerosil".

[0132] It should be understood that the grease composition according to the invention may contain a thickener or a mixture of thickeners. In the case of a mixture of thickeners, it may be a mixture of thickeners from the same family (e.g., a mixture of different (poly)ureas) or a mixture of thickeners from different families (e.g., a mixture of metal soaps and sulfonate soaps). Preferably, the total amount of thickener in the grease composition according to the invention is between 5% by weight and 25% by weight, more preferably between 10% by weight and 20% by weight, relative to the total weight of the grease.

[0133] Other optional functional additives:

[0134] The grease compositions according to the invention may further comprise one or more other functional additives known to those skilled in the art, particularly selected from corrosion inhibitors, solid lubricants, anti-wear additives, extreme pressure additives, antioxidants, metal passivators, coupling agents, friction modifiers, viscosity index improvers, flame retardants, and defoaming additives. It should be understood that these other functional additives differ from the sulfur-containing compounds of general formula (I) according to the invention.

[0135] Specifically, the total amount of other functional additives is 0.1% to 20% by weight, preferably 1% to 15% by weight, and more preferably 1% to 10% by weight, relative to the total weight of the lipids.

[0136] Preferably, the grease according to the invention contains another anti-wear additive, and more preferably contains an anti-wear additive selected from zinc dialkyl dithiophosphate or zinc diaryl dithiophosphate.

[0137] The following functional additives may be specifically mentioned.

[0138] Anti-wear additives

[0139] In anti-wear additives, organophosphorus compounds, and more specifically organophosphorus-sulfur compounds, are commonly used. Therefore, it can be mentioned that:

[0140] Thiophosphoric acid, thiophosphorous acid, esters or salts of these acids, alkoxylated phosphate esters, phosphate amines, dithiophosphate esters or salts and mixtures thereof, preferably zinc dithiophosphate.

[0141] As described above, in the context of this invention, zinc dialkyl dithiophosphate or zinc diaryl dithiophosphate is most particularly preferred as an additional anti-wear additive. Specifically, the zinc dithiophosphate has the following general formula (II):

[0142] [Chemical Formula 1]

[0143]

[0144] in:

[0145] Group R10 To R 13 Each of these terms independently represents an aromatic or non-aromatic, straight-chain, branched, or cyclic hydrocarbon chain containing 1 to 24 carbon atoms. Preferably, the hydrocarbon chain is a straight-chain or branched chain containing 1 to 24 carbon atoms, more preferably 3 to 12 carbon atoms, for example 6 to 10 carbon atoms.

[0146] These compounds, for example, were produced by Kusa Chemicals under the name Kunox S8811 (CAS: 4259-15-8C). 32 H 68 O4P2S4Zn) for sale

[0147] [Chemical Formula 2]

[0148]

[0149] When combined with sulfur-containing compounds of general formula (I) according to the invention, zinc dialkyl dithiophosphate and / or zinc diaryl dithiophosphate can achieve improved anti-wear effects, or even synergistic effects.

[0150] The total amount of anti-wear additives relative to the total weight of grease can be from 0.1% to 20% by weight, preferably from 0.1% to 10% by weight and more preferably from 0.1% to 5% by weight.

[0151] Extreme pressure additives

[0152] Compounds containing organosulfur, organochlorine, and organophosphorus compounds, and mixtures thereof, are particularly suitable as extreme pressure additives.

[0153] For example, you can use:

[0154] -Chlorinated paraffin;

[0155] -alkyl or alkylphenol polysulfides, sulfurized olefins, sulfur-containing esters, metal dithiocarbamates, thiadiazoles and benzothiazides; and

[0156] - Alkyl phosphate esters or alkyl phosphonate esters, phosphoric acid, phosphorous acid, phosphorous acid and phosphoric acid monoesters, diesters and triesters and their salts.

[0157] The total amount of fat can be from 0.1% to 20% by weight, preferably from 0.1% to 10% by weight and more preferably from 0.1% to 5% by weight.

[0158] Corrosion inhibitors

[0159] Boric acid and its salts, toluenetriazole and its salts, benzotriazole and its salts, imidazoline and its salts, alkanolamines and amides, sulfonates, alkali metal salts and alkanolamine salts of naphthenic acids, amine salts of phosphate esters, alkali metal nitrites, alkali metal carbonates, carboxylic acids and their derivatives, alkylsulfonamide carboxylic acids, arylsulfonamide carboxylic acids, phenoxy derivatives, sodium molybdate, alkoxylated amines, tertiary polyamines (e.g., pentamethyldipropylenetriamine) and their salts, polyalkylene glycol alkyl ether phosphates and mixtures thereof are used as corrosion inhibitors.

[0160] Their total amount relative to the total weight of fat can be from 0.1% to 10% by weight, preferably from 0.1% to 5% by weight.

[0161] solid lubricants

[0162] Molybdenum disulfide, tungsten derivatives such as tungsten salts, tungsten oxides as described in document JP 2009114459, tungsten disulfide, graphite, PTFE, talc, zinc oxide, and mixtures thereof are particularly used as solid lubricants. The total amount of solid lubricant relative to the total weight of grease can be from 0.1% to 10% by weight, preferably from 0.1% to 5% by weight.

[0163] antioxidants

[0164] Phenolic derivatives, amines, and mixtures thereof are typically used as antioxidants, and their total amount relative to the total weight of lipids can be from 0.1% to 10% by weight, preferably from 0.1% to 5% by weight.

[0165] Metal passivating agent

[0166] Triazoles are commonly used as metal deactivators. The total amount relative to the total weight of the lipid can be from 0.1% to 10% by weight, preferably from 0.1% to 5% by weight.

[0167] Coupling agent

[0168] Alcohols, C8-C18 alkoxylated alcohols, such as phenoxypropanol and isopropanol, and mixtures thereof, may be added as coupling agents. The total amount may be from 0.1% to 10% by weight relative to the total weight of the ester, preferably from 0.1% to 5% by weight.

[0169] Friction modifier

[0170] The friction modifier is specifically selected from fatty acid esters, alkoxylated (di)amines, and mixtures thereof. Its total amount relative to the total weight of the fat can be between 0.1% by weight and 10% by weight.

[0171] Specifically, the grease compositions according to the invention contain little or no chlorinated paraffin (e.g., less than 10% by weight, for example, between 0.1% and 10% by weight). Specifically, the grease compositions contain little or no chlorinated compounds or more generally halogenated compounds (e.g., less than 10% by weight, for example, between 0.1% and 10% by weight). Specifically, the grease compositions according to the invention do not contain chlorinated compounds or more generally halogenated compounds as extreme pressure and / or anti-wear additives.

[0172] Specifically, the ester composition does not contain organic salts of polyvalent metals or esters of polyols. Such compounds are particularly described in document FR70851E. Preferably, the ester composition contains strictly less than 1% by weight of esters of polyols and / or strictly less than 0.01% by weight of organic salts of polyvalent metals relative to the total weight of the base oil. More particularly, the ester composition does not contain oil-soluble emulsifiers (particularly those soluble in the base oil as defined above), or even any emulsifiers at all.

[0173] More specifically, the grease composition contains only sulfur-containing compounds of general formula (I) as defined above as extreme pressure and / or anti-wear additives. In particular, the grease composition contains only sulfur-containing compounds of general formula (I) as defined above and optionally zinc dialkyl dithiophosphate or zinc diaryl dithiophosphate as anti-wear additives, preferably in greases containing metal soaps as defined above.

[0174] Preferred lipid compositions according to the present invention comprise (or consist of):

[0175] -0.1% by weight to 10% by weight of sulfur-containing compounds of general formula (I) as defined above;

[0176] -75% to 90% by weight of one or more base oils as defined above, preferably one or more mineral oils;

[0177] -5% to 20% by weight of the thickener as defined above, preferably a metal soap and / or (poly)urea; and

[0178] - Other functional additives, from 0.1% to 10% by weight relative to the total weight of the composition, preferably selected from corrosion inhibitors, solid lubricants, anti-wear additives, extreme pressure additives, antioxidants, metal deactivators, coupling agents, friction modifiers, viscosity index modifiers, flame retardants, and defoaming additives.

[0179] The grease compositions according to the invention can be prepared by methods conventional to those skilled in the art, particularly by mixing various components. Typically, a thickener is mixed with a base oil to form a grease under stirring and heating (usually between 25°C and 100°C, depending on the nature of the thickener), followed by the addition of various additives. Sulfur-containing compounds of general formula (I) can also be added to commercially available grease compositions. Attached Figure Description

[0180] Figure 1

[0181] [ Figure 1 The figure shows the welding load (i.e. the load on the welded balls during the 4-ball test) achieved in kgf as a function of the different lithium greases used.

[0182] Figure 2

[0183] [ Figure 2 The figure shows the weld load achieved in kgf (i.e., the load on the welded balls during the 4-ball test) as a function of the different (poly)urea esters used.

[0184] Figure 3

[0185] [ Figure 3 The figure shows the average diameter of the wear marks as a function of the various poly(urea) resins used.

[0186] Figure 4

[0187] [ Figure 4 The figure shows the average diameter of the wear marks obtained as a function of the various lithium greases used.

[0188] Example

[0189] Example 1: Extreme Pressure (EP) Properties of Homocysteine ​​in Lubricating Grease

[0190] 4-ball test

[0191] 1- program

[0192] The four-ball test is used to determine the extreme pressure properties of lubricating grease. It is performed according to ASTM D2596-20 Standard Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method).

[0193] Homocysteine ​​may be added to lipids containing thickeners based on lithium soap or (poly)urea.

[0194] The lipid composition prior to the addition of homocysteine ​​is as follows:

[0195] Lithium soap

[0196] The grease used is sold by Nippon Grease Co. Ltd under the name Niglube MP-DX N°2. It contains:

[0197] 80% to 90% by weight of mineral oil;

[0198] 10% to 20% by weight of lithium soap as a thickener; and

[0199] Additives less than 10% by weight.

[0200] (poly)urea

[0201] The grease used is sold by Nippon Grease Co. Ltd under the name Nigace UR-2. It contains:

[0202] 80% to 90% by weight of mineral oil;

[0203] 10% to 20% by weight of urea-type thickeners; and

[0204] Additives less than 10% by weight.

[0205] Added to these formulations is 4.3% by weight of homocysteine ​​relative to the total weight of each of the above lipid compositions (referred to as starting lipids) (i.e., 4.1% by weight of homocysteine ​​relative to the total weight of the lipids added).

[0206] Lipids without added homocysteine ​​were used as a control.

[0207] Extreme pressure measurements are performed by rotating a stainless steel ball over three stationary balls, also made of stainless steel, all four of which are completely covered with grease. A load is applied to the balls and gradually increased (per minute according to the parameters below) until the balls are welded together. The balls are replaced before each increase in load.

[0208] Extreme pressure effect corresponds to the load value at which four balls are welded together, thus preventing the upper ball from rotating on the other three balls. The greater the load, the higher the extreme pressure effect.

[0209] The 4-ball test was conducted under the following conditions:

[0210] Speed: 1450 + / - 50 rpm

[0211] -Steel ball: 100Cr6

[0212] 2- result

[0213] The result is in [ Figure 1 ]and[ Figure 2 As given in [].

[0214] For lithium soap grease, a higher welding load (250 kgf vs. 160 kgf) was observed in the presence of homocysteine: therefore homocysteine ​​has extreme pressure properties.

[0215] Replace the ball before each increase in load.

[0216] This significant extreme pressure effect was compared to that of commercial extreme pressure additives. A commercial additive was added to the same urea ester at a rate of 4.5% by weight relative to the total weight of the starting ester. The additive was TPS20® sold by Arkema. The extreme pressure effect obtained with homocysteine ​​was much greater, almost twice that of TPS20® (which is a dialkyl trisulfide).

[0217] Finally, the same four-ball test was performed in the lithium soap grease by replacing 4.3% by weight of homocysteine ​​with 4.3% by weight of cysteine. A welding load of 200 kgf was observed, which also demonstrates the extreme pressure performance of the cysteine ​​in the grease according to the present invention.

[0218] Example 2: Anti-wear properties of homocysteine ​​in grease

[0219] 4-ball test

[0220] 1- program

[0221] Wear resistance testing was conducted according to standard IP 239 (2014): "Determination of extreme-pressure and anti-wear properties of lubricating fluids and greases - four ball method (European conditions)".

[0222] For this test, the same four-ball apparatus as in Example 1 was used. All four balls were fully coated with grease. A load of 40 kgf was applied to the fourth ball for 1 hour. The diameter of the wear mark on each of the other three balls was then recorded. The average of the three readings gives the average diameter of the wear mark. The smaller the mark, the higher the wear resistance.

[0223] The 4-ball test was conducted under the following conditions:

[0224] Speed: 1450 + / - 50 rpm

[0225] -Steel ball 100Cr6

[0226] Using the same starting urea-coated spheres as in Example 1, add:

[0227] -4.3% by weight zinc dithiophosphate (ZDDP) - a commercial anti-wear additive, or

[0228] -4.3% by weight of homocysteine,

[0229] The weight percentage is relative to the total weight of the starting lipid composition (i.e., 4.1% relative to the total weight of the lipids added). Unadded lipids were used as a control.

[0230] 2- result

[0231] The result is in [ Figure 3 As given in [].

[0232] A reduction in the average diameter of wear tracks was observed using homocysteine ​​(0.433 mm vs. 0.641 mm). Furthermore, this reduction was greater than that obtained with ZDDP, a commercial anti-wear additive (0.433 mm vs. 0.534 mm). Therefore, homocysteine ​​exhibits anti-wear properties.

[0233] The same tests were performed on the same lithium soap ester as in Example 1, in which:

[0234] -4.3% by weight of zinc dithiophosphate (ZDDP), or

[0235] -2.15% by weight ZDDP and 2.15% by weight homocysteine,

[0236] The weight percentage is 4% by weight and 2% by weight relative to the total weight of the starting lipid composition (i.e., 4% by weight and 2% by weight relative to the total weight of the added lipids).

[0237] The result is in [ Figure 4 As given in the literature, it is shown that homocysteine ​​in combination with ZDDP can reduce the average diameter of wear tracks even more.

Claims

1. A lipid composition comprising: a) Sulfur-containing compounds or their salts of the following general formula (I): R3-X-CH(NR1R2)-(CH2) n -(S) P -Z (I) in: -Z represents a hydrogen atom or -(CH2). n -CH(NR1R2)-X-R3 group; -R1 and R2 may be the same or different, and are selected from: hydrocarbon chains with 1 to 20 carbon atoms and may contain one or more heteroatoms, whether they are hydrogen atoms or saturated or unsaturated; straight-chain, branched or cyclic; aromatic or non-aromatic. -X is selected from -C(=O)-, -CH2-, or -CN; -R3 is: (i) Zero when X represents -CN (ii) or hydrogen atom, (iii) or -OR a R a Hydrocarbon chains having 1 to 20 carbon atoms and may contain one or more heteroatoms, and may be straight-chain, branched or cyclic, aromatic or non-aromatic, consisting of hydrogen atoms or saturated or unsaturated hydrocarbons. (iv) or -NR b R c R b and R c Same or different, selected from: hydrocarbon chains having 1 to 20 carbon atoms and possibly containing one or more heteroatoms, whether hydrogen atoms are saturated or unsaturated; straight-chain, branched or cyclic; aromatic or non-aromatic. -n is an integer equal to 1 or 2; and -p is an integer from 1 to 8; The condition is that if Z is a hydrogen atom, then p equals 1; b) One or more base oils; c) One or more thickeners; and d) One or more optional functional additives.

2. The lipid composition according to claim 1, wherein the sulfur-containing compound has the following general formula (Ia) or a salt thereof: R3-X-CH(NR1R2)-(CH2) n -SH (Ia) R1, R2, R3, X, and n are defined as in claim 1.

3. The lipid composition according to claim 1, wherein the sulfur-containing compound is selected from the group consisting of: Cysteine, cystine, homocysteine, dicysteine ​​trisulfide, dicysteine ​​tetrasulfide, dicysteine ​​pentasulfide, dihomocysteine ​​trisulfide, dihomocysteine ​​tetrasulfide, dihomocysteine ​​pentasulfide and their salts, with homocysteine ​​being preferred.

4. The lipid composition according to any one of the preceding claims, wherein the amount of the sulfur-containing compound of general formula (I) is between 0.1% by weight and 50% by weight, preferably between 0.1% by weight and 20% by weight, and more preferably between 0.1% by weight and 10% by weight, relative to the total weight of the lipid.

5. The lipid composition according to any one of the preceding claims, wherein the thickener is selected from: metallic soaps of fatty acids, (poly)urea, sulfonates, polyamides, polyimides, polytetrafluoroethylene (PTFE), silica gel, aluminosilicates, modified clay, graphite, carbon black, boron nitride, and mixtures thereof; preferably selected from metallic soaps of fatty acids, (poly)urea, and sulfonates.

6. The lipid composition according to any one of the preceding claims, wherein, The total amount of thickener relative to the total weight of the grease is between 5% and 25% by weight, preferably between 10% and 20% by weight.

7. The grease composition according to any one of the preceding claims, wherein the total amount of base oil is between 75% and 95% by weight, preferably between 80% and 90% by weight, relative to the total weight of the grease.

8. The composition according to any one of the preceding claims, comprising one or more other functional additives selected from corrosion inhibitors, solid lubricants, anti-wear additives, extreme pressure additives, antioxidants, metal deactivators, coupling agents, friction modifiers, viscosity index improvers, flame retardants, and defoaming additives.

9. The composition according to claim 8, wherein zinc dithiophosphate is contained as an anti-wear additive.

10. Use of grease as defined in any one of claims 1 to 9 for lubricating mechanical devices, wherein the mechanical devices are preferably selected from rolling and sliding bearings, gears, cables, chains, reels, and mechanical devices that do not include a sealing system.

11. Use of a sulfur-containing compound of general formula (I) as defined in any one of claims 1-3, or a salt thereof, as an anti-wear and / or extreme pressure additive.

12. The use according to claim 11, wherein the sulfur-containing compound is selected from: Cysteine, cystine, homocysteine, dicysteine ​​trisulfide, dicysteine ​​tetrasulfide, dicysteine ​​pentasulfide, dihomocysteine ​​trisulfide, dihomocysteine ​​tetrasulfide, dihomocysteine ​​pentasulfide and their salts, with homocysteine ​​being preferred.

13. A method for lubricating a metal or composite material, comprising the step of contacting the metal or composite material with a grease, the grease comprising a sulfur-containing compound of general formula (I) as defined in any one of claims 1 to 3 or a salt thereof.

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